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HomeMy WebLinkAbout2908 S TIMBERLINE RD MULTI-FAMILY DWELLINGS - PDP210011 - SUBMITTAL DOCUMENTS - ROUND 2 - DRAINAGE REPORTTIMBERLINE ATTAINABLE HOUSING DRAINAGE REPORT CITY OF FORT COLLINS, COLORADO Martin/Martin, Inc. Project No.: 20.0336 August 18, 2021 Prepared For: TETRAD PROPERTY GROUP 1730 SOUTH COLLEGE AVENUE, UNIT #200 FORT COLLINS, COLORADO 80525 970.658.4312 Prepared By: MARTIN/MARTIN, INC. 12499 WEST COLFAX AVENUE LAKEWOOD, COLORADO 80215 303.431.6100 Principal-in-Charge: Scott E. Paling, PE Project Manager: Melyssa C. Hartzell, PE Project Engineer: Tom Ogren, EIT II CERTIFICATION STATEMENT This report for the drainage design of the Timberline Attainable Housing Project was prepared by me (or under my supervision) in accordance with the provisions of City of Fort Collins Stormwater Criteria Manual and is designed to comply with the provisions thereof. I understand that the City of Fort Collins does not, and will not, assume liability for drainage facilities designed by others. Scott E. Paling, PE Date: Registered Professional Engineer State of Colorado PE No.: 37116 8/18/2021 TABLE OF CONTENTS I. GENERAL LOCATION AND DESCRIPTION.....................................................................................................1 A. Location...................................................................................................................................................1 B. Description of Property...........................................................................................................................1 C. Floodplain Submittal Requirements........................................................................................................2 II. MAJOR DRAINAGE BASINS..........................................................................................................................2 A. Major Basin Description..........................................................................................................................2 III. PROJECT DESCRIPTION................................................................................................................................3 IV. PROPOSED DRAINAGE FACILITIES...............................................................................................................4 A. General Concept .....................................................................................................................................4 B. Sub-Basin Description .............................................................................................................................5 C. Detention Basin/ Outlet Design ..............................................................................................................6 D. Water Quality Capture Volume (WQCV) Design.....................................................................................7 E. Low Impact Development (LID) Design...................................................................................................8 F. Drainage Easements/Maintenance Access.............................................................................................9 V. DRAINAGE DESIGN CRITERIA.......................................................................................................................9 A. Regulations..............................................................................................................................................9 B. Previous Studies......................................................................................................................................9 C. Four Step Process....................................................................................................................................9 D. Development Criteria Reference and Constraints ................................................................................10 E. Hydrological Criteria..............................................................................................................................11 A. Hydraulic Criteria ..................................................................................................................................11 VI. VARIANCE REQUESTS................................................................................................................................12 A. Floodplain Regulations Compliance......................................................................................................12 B. Modifications of Criteria .......................................................................................................................12 VII. EROSION CONTROL...................................................................................................................................12 VIII. CONCLUSIONS...........................................................................................................................................12 A. Compliance with Standards ..................................................................................................................12 B. Drainage Concept..................................................................................................................................12 REFERENCES......................................................................................................................................................13 APPENDICES Appendix A - Maps 1. Vicinity Map 2. FEMA FIRM Map 3. Fort Collins Flood Hazard Map 4. NRCS Soils Map 5. USFW Wetlands Mapper 6. ECS Report Feature Delineations Appendix B - Hydrologic Calculations 1. Development Imperviousness Assessment 2. Proposed Rational Calculations Appendix C - Hydraulic Calculations 1. Detention Pond Calculations-SWMM Model/ Volume Calculations 2. Water Quality and Low Impact Development (LID) Calculations and Exhibit 3. SDI Calculations Appendix D - Supporting Documents 1. Geotechnical Report 2. Foothills Basin Map 3. Pinecone PUD Drainage Plan 4. Ft. Collins IDF Curves 5. 2007 SWMM Basin Calculations Appendix E - Drainage Plans 1. 2007 Report Drainage Plan 2. Existing Drainage Plan 3. Proposed Drainage Plan 4. Water Quality Treatment Train P a g e 1 | 12 I. GENERAL LOCATION AND DESCRIPTION A. Location The Timberline Housing (hereafter referred to as “PROJECT”) site is located at 3008 South Timberline Road Fort Collins, Colorado 80525, adjacent to Timberline Church. The PROJECT lies within the Tract A and Lots 1, 2, and 5 of the Timberline Church P.U.D. specifically, in the West half of Section 29, Township 7 North, Range 68 West of the 6th Principal Meridian, City of Fort Collins, Larimer County, State of Colorado. The PROJECT is bound to the north and east by apartment complexes associated with the Rigden Farm development, to the south by the Foothills Channel and Rendezvous Trail, and to the west by Timberline Church and parking lot. Adjacent major roadways around the PROJECT site include South Timberline Road to the west and Custer Drive to the north. Refer to the vicinity map below and in the Appendix. Figure 1 - Vicinity Map, NTS B. Description of Property The PROJECT area site consists of approximately 10 acres of disturbed area. The existing site consists of native grasses, existing asphalt drives and parking areas, concrete sidewalks, an existing water quality and detention pond, and a drainage swale. The current Timberline Church property drains to the southeast and into a drainage swale or detention pond which then releases through two outlet structures into the Foothills Channel. The site drains through curb TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 2 | 12 and gutter, storm inlets and storm pipe, or overland flow. The PROJECT is located within the Foothills Master Drainage Basin. According to the “Geotechnical Engineering Report” produced by Terracon Consultants, dated May 5, 2021, the existing soils consist of silt or clay with varying amounts of sand and gravel over about 4 to 12 feet of sand and gravel. Bedrock was found at depths of approximately 17 to 21 feet below grade. Groundwater was encountered in all of the test borings at about 12 to 13 feet below existing site grades. A copy of the Geotechnical Report can be found in the Appendix. A USDA NRCS web soil survey of the PROJECT site states that the soils consist mostly of Nunn clay loam Type C Hydrologic Soils. The HSG C is the predominate soil type across the site and was used for runoff calculations. Soils with an HSG of C have a very slow infiltration rate when thoroughly wet and therefore have high runoff potential. A copy of the web soil survey is referenced in the Appendix. C. Floodplain Submittal Requirements The Flood Insurance Rate Map Number 08069C1000F Panel 1000 of 1420, dated December 19, 2006, shows that the proposed development is not located within the 100-year floodway area. The FEMA FIRMETTE Map is in Appendix A. According to the City of Ft Collins, the Foothills Channel is considered a High Risk Floodway. The floodway limits remain within the channel. Because the channel and existing detention pond are hydraulically connected, there is a possibility of back flow into the pond when the Foothills Channel WSEL is higher than the WSEL in the detention facility. A map showing the Ft. Collins Floodway is included in Appendix A. The proposed design is in accordance with the “City of Fort Collins Floodplain Review Checklist for Development Review Submittals.” II. MAJOR DRAINAGE BASINS A. Major Basin Description The PROJECT lies entirely within the Foothills Basin which is generally bound by Taft Hill, Ziegler, Horsetooth, and Drake Road. A Master Plan for the Foothills Basin was completed in 1981. In 1994, the Pinecone PUD Overall Drainage Plan divided the PROJECT site into two Major Basins, 59 and 60. In this report Basin 60 discharged into the channel undetained, while Basin 59 was slightly detained. Total releases from the site were limited to 97 cfs. In 1999, the site was further developed as outlined in the referenced Final Drainage Report. Water quality was provided my means of an extended detention facility. Improvements limited discharge from the detention facility to 20 cfs. The 2007 Final Drainage study included major developments to the site. This report utilized a “beat-the-peak” methodology to establish a new allowable site release of 82 cfs. The 1999 TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 3 | 12 Report also included an additional outfall to Foothills Channel and provided an overall site impervious design value based on future development plans. The PROJECT lies within several sub-basins developed in the 2007 Report. The affected basins (A2, A3, B3, B4, C2, D1, D2, and E) were eliminated and replaced with new basins (P1 thru P14, and D1). The proposed development has an overall site imperviousness (Basins 59 and 60) below the designed imperviousness values established within the 2007 report. Therefore, the “beat-the-peak” methodology utilized to design the detention pond remained applicable. Enhanced water quality features were integrated into the design as required by City of Fot. Collins water quality standards. Between the 2007 Report and the PROJECT, the accepted vertical datum has changed from NGVD29 to NAVD88. This results in a vertical increase of 3.19’ for all elevations referenced in prior reports. III. PROJECT DESCRIPTION The total PROJECT site is approximately 10 acres. The proposed development will include the construction of seven multifamily residential units, private drives and parking lots, and utility infrastructure necessary to service the proposed buildings. Additionally, drainage facilities designed to improve Stormwater Quality are proposed for the site in accordance with Chapter 7- Water Quality of the City of Fort Collins Stormwater Criteria Manual. The PROJECT design includes the modification of the extended detention pond as well as the drainage swale that provides detention and treats water quality for the 100-year storm for the added impervious area with the proposed PROJECT development. Various design criteria were changed throughout the development of the site. Where comparisons were made, like criteria was utilized to maintain consistency. The following assessments were performed: 1.Comparison of existing and proposed imperviousness: Criteria effective (surface impervious values) to the 2007 report were utilized when comparing the proposed project to the established design of the site. 2.Pipe, Inlet, and Conveyance capacities: current criteria with the Rational Method. 3.Proposed Water Quality and LID Design: current criteria with the Rational Method. 4.Assessment of the As-Build Detention Facility: current criteria with EPA SWMM. TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 4 | 12 IV. PROPOSED DRAINAGE FACILITIES A. General Concept The proposed drainage basins located on the PROJECT site consist of pavement, proposed building roof, landscaped areas, sidewalk and paved walking paths, paved parking lots, an extended detention pond and a drainage swale. The north quarter of the site drains to the drainage swale. The remainder of the site drains to the extended detention pond. About 75% of the PROJECT site drains to proposed LID systems before discharging into the detention pond and then discharging offsite into the Foothills Channel. The remaining 25% of the PROJECT site discharges directly to the existing detention pond where water quality is treated and stored before discharging offsite into the Foothills Channel. The balance of the existing site remaining undisturbed will maintain existing drainage ways to the existing detention pond prior to discharging offsite to the Foothills Channel. The proposed flow conditions are not expected to change drastically from existing conditions. The developed imperviousness of the site was compared to the originally designed imperviousness. To establish the existing condition, areas that are currently fully developed were assigned surface type areas (pavement, gravel, roof, or landscaping) based on current aerial imagery. Areas of future/proposed development (from the 2007 report) were assigned surface areas similar to the 2007 Report. These areas were compared to the design values tabulated in the original design report. It was concluded from this analysis that the overall site was originally calculated at a complete developed composite imperviousness of 75.5%. This is the imperviousness found in the 2007 report and utilized for the Water Quality Volume calculations. A composite imperviousness of 80% was utilized in the SWMM analysis of the detention pond in the 2007 report as well. Because portions of the proposed work assessed in the 2007 study, an updated “projected- developed” imperviousness was also calculated which accounted for the as-built condition of the site thus far, the current “projected-developed” developed composite imperviousness was calculated at 73.3%. A summary of these values is shown below in Table 1. To determine the developed composite imperviousness following completion of the PROJECT, modified basins were replaced with proposed basins and an overall imperviousness was calculated. The result was 72.5%, slightly below the current “projected-developed” state of 73.3% and well below the originally design values for water quality and detention of 75.5% and 80%. Detailed impervious calculations are included in Appendix B. TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 5 | 12 Table 1: Composite Site Imperviousness Summary Value Current Study 2007 Report Site Area (acres)32.76 32.82 Current Composite I (%)73.3 75.5 Imperviousness for Pond Design (%)80%80% B. Sub-Basin Description Existing Drainage In the existing condition, stormwater runoff generated on site is conveyed via overland flow to existing storm inlets or curb and gutter. The inlets then flow through existing RCP storm sewer which drains to both detention ponds. The project site that doesn’t flow into storm sewer flows as overland flow directly into the detention pond. Table 2 below provides a summary of the existing site imperviousness. Refer to Appendix E for the 2007 Drainage plan and the current Existing Drainage Plan. Peak flows for existing basins were not calculated as part of an existing site analysis. Table 2: Summary of Existing Basins Basin Design Point Area (Acres) % IMP. A1 A1 6.39 82 A2 A2 0.31 98 A3 A3 2.16 65 A4 A4 0.08 90 B1 B1 1.69 92 B2 B2 0.90 91 B3 B3 1.71 100 B4 B4 1.35 92 B5 B5 0.04 100 C1 C1 3.31 92 C2 C2 0.09 0 D1 D1 1.82 90 D2 D2 2.10 91 E1 E1 7.65 56 SITE COMPOSITE 32.82 73.3% Proposed Drainage Runoff generated from the proposed development is conveyed via overland flow towards storm inlets, curb and gutter, and roof drains before being conveyed to rain gardens, swales, underground filtration systems, or the existing detention ponds. The rain gardens, grass swales, and underground filtration systems will provide water quality treatment for the site and the detention ponds will provide detention and water quality treatment. Runoff from this site is ultimately tributary to the Foothills Channel. Refer to Appendix E for the Proposed Drainage Plan and basin delineation. See Table 3 for a summary of the proposed and existing basins. Note that the overall site imperviousness shown in the rational calculations is higher that the “projected-developed” imperviousness calculated above. As indicated above, the rational TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 6 | 12 analysis used the current value of 2% for landscaped areas where the overall site imperviousness assessment compared the conditions utilizing the 2007 report landscape impervious value of 0%. Table 3: Summary of Proposed Basins Basin Design Point Area (Acres) % IMP.C10 C100 Q10 (CFS) Q100 (CFS) P1 P1 0.16 89.8%0.82 0.91 0.46 1.48 P2 P2 0.95 58.1%0.54 0.72 1.74 6.82 P3 P3 1.16 75.8%0.66 0.79 2.61 9.15 P4 P4 0.20 53.9%0.49 0.68 0.32 1.34 P5 P5 0.20 69.2%0.63 0.78 0.42 1.52 P6 P6 0.46 80.8%0.74 0.86 1.14 3.90 P7 P7 0.83 83.5%0.75 0.86 2.11 7.09 P8 P8 1.62 3.3%0.17 0.52 0.88 7.84 P9 P9 0.44 70.8%0.60 0.73 0.90 3.22 P10 P10 0.72 76.2%0.71 0.84 1.74 6.04 P11 P11 1.11 49.7%0.50 0.71 1.87 7.81 P12 P12 0.44 71.0%0.63 0.77 0.94 3.36 P13 P13 0.33 99.1%0.89 0.96 1.00 3.16 P14 P14 0.44 99.3%0.89 0.96 1.31 4.16 A1 A1 6.39 82.2%0.77 0.88 13.04 43.40 A4 A4 0.08 90.0%0.75 0.83 0.20 0.64 B1 B1 1.69 91.9%0.84 0.92 4.05 13.05 B2 B2 0.90 90.9%0.83 0.92 2.36 7.73 B5 B5 0.04 100.0%0.90 0.96 0.12 0.38 C1 C1 3.31 91.7%0.84 0.92 7.88 25.50 C3 C3 1.82 90.3%0.75 0.83 4.17 13.27 C4 C4 2.10 90.8%0.76 0.84 4.93 16.43 D1 D1 7.40 56.5%0.57 0.76 7.98 30.69 OS1 OS1 3.02 90.2%0.83 0.91 6.72 21.22 OS2 OS2 1.41 90.2%0.83 0.91 3.14 9.92 SITE COMPOSITE 37.21 37.21 75.0%0.70 0.83 72.01 Basins in Italics are existing C. Detention Basin/ Outlet Design Per the 2007 report, the detention pond consists of three hydraulically connected sections: swale, north, and south ponds. For the remainder of this report, the term Pond will imply the composition of these three sections. Recently surveyed topography was used in the development of the existing pond’s stage-storage curve. The design approach (Beat the peak) of the detention pond swale was not changed. Minor infilling into the pond will occur with the PROJECT resulting in decreased storage capacity. This reduction is offset by enlarging the pond in different areas. The existing and proposed state- storage curves are shown in Appendix C along with a comparison of the two. The net result is a pond with slightly more storage capacity from the as-built condition. TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 7 | 12 The detention pond was analyzed using EPA SWMM Version 5.1. Basin information from the 2007 Report and current Fort Collins Drainage Criteria was utilized to develop sub catchments SWMM. Basins 59 and 60 were assumed to be at a fully developed imperviousness of 80%, exceeding the current PROJECT effective imperviousness. Both outlet structures were modeled in SWMM using recent survey information. Only detained release curves were developed for the outlet structures as culverts as the releases from the water quality orifice plates are minor compared to the outlet pipes. An updated peak storage volume and discharge was determined by routing inflows through the SWMM model. Detailed EPA SWMM documents are included in Appendix Table 4: Existing Pond Summary Table Value Current Study 2007 Report Detained Volume (acre-feet)2.003 3.700 Water Quality Volume (acre-feet)0.889 0.991 Peak Release (cfs)62.13 82 D. Water Quality Capture Volume (WQCV) Design The PROJECT site was designed using the Four Step Process outlined in the Fort Collins Stormwater Criteria Manual. The PROJECT site utilizes a combination of rain gardens (bioretention), grass swales, underground filtration systems, and extended detention basins to provide water quality treatment for the PROJECT. The PROJECT does not use any permeable pavers; therefore the 75/25 rule applies. 75% of the modified surfaces will be treated by approved LID Systems while the balance can be treated by standard practices. Most of the PROJECT area requires surface modification as both the surface type and flow patterns change. However, the improvements associated with the PROJECT within the private road and existing parking lot north of the PROJECT within Basins A1, B1, P13, and P14, consist of utility installation and pavement replacement. The flow patterns and surface types in these areas do not change. After discussion with City Staff, those basins are not included in the overall modified surface total and do not contribute to the 75/25 LID requirement. Approximately 75% of the site WQCV was treated using rain gardens, grass swales, or underground filters while the remaining 25% of the site was routed to the existing extended detention basin. A summary of the system distribution is shown below in Table 5. Refer to the Appendix C for detailed rain garden, grass swale, and new volume for the extended detention basin calculations. TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 8 | 12 Table 5: Water Quality Treatment Distribution System Type % Impervious Area WQCV (CF) EDB 18%35853 RAIN GARDEN A 18%891 RAIN GARDEN B 14%663 UG FILTRATION A 8%452 UG FILTRATION B 16%848 UG FILTRATION C 15%732 SWALE A 12%0 (In EDB) E. Low Impact Development (LID) Design A variety of Low-Impact-Design (“LID”) features were incorporated into the drainage design for this project. The following are descriptions of the LID features used in the PROJECT design: Bioretention (Rain Gardens): Rain gardens have been designed in accordance with the design and construction detailing for bioretention systems from the Fort Collins Stormwater Criteria Manual. There are 2 proposed rain gardens located throughout the PROJECT site. A 12-hour drain time was used when designing the rain gardens and all the rain gardens drain into the extended detention basins where it is then eventually discharged offsite. Several proposed drainage basins drain directly to the rain gardens via overland flow. No more than two drainage basins are directed to one rain garden. The rain gardens will be designed with one foot of water quality ponding depth. An inlet of weir will be provided in the rain gardens for an 100 Year overflow path that discharges directly into the extended detention basin. Underdrain piping will be provided within the rain garden as well as underdrain cleanouts as required in the Manual. Refer to Appendix C for detailed rain garden calculations. Grass Swale: Grass swales have been designed in accordance with the Grass Swale Best Management Practice Fact Sheet and Design Spreadsheet from the MANUAL. There is one proposed grass swale on the PROJECT site. This swale was designed using UDFCD UD-BMP spreadsheet and followed the CRITERIA and MANUAL. This facility will provide LID/Filtration treatment only, while the WQCV is still contained in the Extended Detention Basin. The site was graded to drain to a low point where the grass swale started and then drains freely into the existing drainage swale to the east with a slope of the grass lined swale at 0.50%. The Grass Swales will be densely vegetated trapezoidal channels with low-pitched side slopes and a relatively broad cross sections which will convey flow in a slow and shallow manner, thereby facilitating sedimentation and filtering while limiting erosion. Calculations for the grass swale is included in Appendix C. Underground Filtration: The underground stormwater BMPs have been designed in accordance with the design and construction detailing for underground infiltration/filtration systems from the Fort Collins Stormwater Criteria Manual. There are three proposed locations where these underground structures will be used throughout the PROJECT site. These were chosen because of space and grading constraints in the specific locations. StormTech chambers were used as a basis of design chosen due to their minimal cover requirements. Refer to Appendix C for detailed rain garden calculations. TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 9 | 12 Treatment Train: The use of a treatment train was used to provide multiple BMPs in series. The use of these LID techniques allows for more consistent treatment of runoff and provide redundancy if one component isn’t functioning as intended. A flow chart and table of the treatment train is provided in the Drainage Plans found in Appendix E. F. Drainage Easements/Maintenance Access All the drainage easements and maintenance accesses are shown on the drainage plans located in Appendix E. Drainage and utility easements will be executed with separate instruments following any replating. V. DRAINAGE DESIGN CRITERIA A. Regulations The drainage design of the project is in compliance with the following criteria: 1. Article VII, Stormwater Utility, City of Fort Collins Municipal Code, latest revision 2. City of Fort Collins Stormwater Criteria Manual, latest revision (“hereafter referred to as the “CRITERIA”). 3. “Urban Storm Drainage Criteria Manual” latest revision (hereafter referred to as the “MANUAL”). B. Previous Studies This drainage report has taken into account the results and recommendations of the previous PUD developed in 2007 for Timberline Church. It has also taken into account the results and recommendations of the previous drainage report developed as part of the 2007 PUD. C. Four Step Process The PROJECT site was designed to Minimize the Directly Connected Impervious Area (MDCIA) and follows the guidelines established in the City of Fort Collins Stormwater Criteria Manual and the MANUAL. The purposed of implementing this Four Step Process is to reduce runoff volumes, treating the WQCV, stabilize streams and implementing long-term source controls, and pertains to the management of smaller, more frequently occurring events. The Four Step Process used for our PROJECT is outlined below. Step 1: Employ Runoff Reduction Practices Currently the site contains open area as well as paved asphalt and concrete surfaces and a existing extended detention pond. The development of site landscaping throughout the site will help slow runoff and encourage infiltration where possible. Minimize Directly Connected Impervious Areas (MDCIA): Drainage design for the proposed residential apartment buildings will discharge roof drain downspouts across pervious landscaped areas to encourage stormwater infiltration where possible. TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 10 | 12 Extended detention pond: All of the proposed and existing runoff will continue to be routed to the existing extended detention basin which is grass lined with a small trickle channel in the center to collect the discharge from storm sewer into the extended detention ponds. Step 2: Implement BMPs that provide a WQCV with slow release. The WQCV for the proposed developed site will mostly be treated through proposed rain gardens, swales, and underground filters located throughout the PROJECT site and the remainder of the WQCV for the site will be treated in the existing extended detention pond. The rain gardens, underground filters, and extended detention ponds will release the WQCV at the rates required by the CRITERIA and MANUAL. The extended detention pond will provide water quality treatment as well as detention. Step 3: Stabilize Streams One of the major drainage channels for the Foothills Basin is located along the southeast side of the PROJECT site. Impacts on the downstream drainageway will be minimized by routing developed flows through LID Systems and controlling the release rate out of the pond to existing flows. Step 4: Implement Site Specific and Other Source Control BMP’s The proposed residential site development will implement Stormwater Management Plans including proper housekeeping practices and spill containment procedures as a separate document when the Final Drainage Report is submitted. Trash enclosures are shown on the construction plans and are labeled. All permeant features will be kept out of the detention basin features. D. Development Criteria Reference and Constraints As such, the PROJECT will provide 100-year detention per the approach approved in the 2007 Report and additional water quality treatment systems will be provided for the modified areas. TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 11 | 12 E. Hydrological Criteria The proposed drainage system is designed in accordance with the CRITERIA and the MANUAL. Per the CRITERIA, the 2-year and 100-year design storm events were as the minor and major storm events, respectively. The Rational Method was used to estimate the minor and major storm runoff generated in the proposed conditions. Impervious and runoff coefficients were obtained from the City of Fort Collins Stormwater Criteria Manual. Soils were classified as NRCS soil Type C for calculations. Refer to the Appendix B for detailed calculations and design aids. Table 6: Hydrologic Criteria Criteria Requirement Reference Design Storm Initial: 2-year-1-hour Major: 100-year-1-hour City of Fort Collins Stormwater Criteria Manual Rational Design Storm Rainfall Depths (inches) 2-Year: 0.82 100-Year: 2.86 Table 3.4-1 IDF Table for Rational Method, Stormwater Criteria Manual Storm Runoff Analysis Method Rational Water Quality WQCV Chapter 7, Stormwater Criteria Manual Detention Release LID Drain Time = 12hrs Extended Detention Basin= 40hrs City of Fort Collins Stormwater Criteria Manual Emergency Overflow 100 Year Peak Inflow City of Fort Collins Stormwater Criteria Manual Flood Plain Determination FEMA Firm Panel City of Fort Collins Flood Maps A. Hydraulic Criteria The required roof drains and pipes are designed to be routed throughout the PROJECT site will be designed and sized by the plumbing engineer. On-site flows will be captured by roof drains, storm inlets, or via overland flow into rain gardens or directly into the existing extended detention ponds. The major and minor storms were considered to have a 100-year and 2-year return interval, respectively. Supporting hydraulic calculations are included in the Appendix C. Table 7 Hydraulic Criteria Criteria Requirement Reference Conduit EGL Initial: within the pipe Major: below finished grade Conduit HGL Initial: within the pipe Major: 1 ft below finished grade Conduit Velocity Initial: 2 fps Major: 10 fps Public ROW Conduit Size Minimum for Public ROW: 15 inches/12 inches vertical for elliptical City of Fort Collins Stormwater Criteria Manual Storm Sewer Modeling StormCAD V8i Local Losses Method Pipe: Hazen Williams Structure: Darcy-Weisbach (K) HEC-22 Water Quality/ LID Design Rain Gardens, Swales, Filters, and Extended Detention Basins UDFCD, Volume 3 Ch 4 and City of Fort Collins Stormwater Criteria Manual TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 12 | 12 VI. VARIANCE REQUESTS A. Floodplain Regulations Compliance No variances from the CRITERIA are requested at this time. B. Modifications of Criteria No MODIFICATIONS from the CRITERIA are requested at this time. VII. EROSION CONTROL The PROJECT will be designed in accordance with all Erosion Control Criteria and Erosion Control Materials and Erosion Control Plans will be submitted the Final Drainage Report VIII. CONCLUSIONS A. Compliance with Standards The Drainage Report for the Timberline Attainable Housing project has been prepared in compliance with the CRITERIA, MANUAL, and the City of Fort Collins Municipal Code, Section 3.4.3 Water Quality. The proposed drainage design is consistent with both existing and developed conditions. B. Drainage Concept Developed runoff will be collected and conveyed by a system of overland flow, roof drains, rain gardens, grass swales, proposed and existing storm sewer directed into the existing water quality and detention pond located in the eastern portion of the site. LID principles will improve the water quality for stormwater runoff from the developed site. Development of the site is not anticipated to adversely impact downstream properties or drainage facilities. H:\LOVATO\20.0336-Timberline Housing\ENG\DRAINAGE\Report\20_0336_May_20_2021_R0_DrainageRpt.docx REFERENCES A. “City of Fort Collins Municipal Code”, Latest revision B. “City of Fort Collins Stormwater Criteria Manual”, Latest revision C. “Geotechnical Engineering Report”, Terracon Consultants, Inc May 5, 2021. D. “Urban Drainage and Flood Control District Drainage Criteria Manual Vol. 1, 2 and 3”, Wright- McLauglin Engineers, Latest revision. E. “Final Drainage and Erosion Control Study for Timberline Church”, Northern Engineering Services, Inc., May 9, 2007 F. “Final Drainage and Erosion Control Study for Timberline Church”, Northern Engineering Services, Inc., December 3, 1999 G. “Overall Drainage Plan for the Pinecone ODP”, Lidstone & Anderson, March 7, 1995 TIMBERLINE ATTAINABLE HOUSING DRAINAGE REPORT CITY OF FORT COLLINS, COLORADO Martin/Martin, Inc. Project No.: 20.0336 August 18, 2021 Prepared For: TETRAD PROPERTY GROUP 1730 SOUTH COLLEGE AVENUE, UNIT #200 FORT COLLINS, COLORADO 80525 970.658.4312 Prepared By: MARTIN/MARTIN, INC. 12499 WEST COLFAX AVENUE LAKEWOOD, COLORADO 80215 303.431.6100 Principal-in-Charge: Scott E. Paling, PE Project Manager: Melyssa C. Hartzell, PE Project Engineer: Tom Ogren, EIT II CERTIFICATION STATEMENT This report for the drainage design of the Timberline Attainable Housing Project was prepared by me (or under my supervision) in accordance with the provisions of City of Fort Collins Stormwater Criteria Manual and is designed to comply with the provisions thereof. I understand that the City of Fort Collins does not, and will not, assume liability for drainage facilities designed by others. Scott E. Paling, PE Date: Registered Professional Engineer State of Colorado PE No.: 37116 8/18/2021 TABLE OF CONTENTS I. GENERAL LOCATION AND DESCRIPTION.....................................................................................................1 A. Location...................................................................................................................................................1 B. Description of Property...........................................................................................................................1 C. Floodplain Submittal Requirements........................................................................................................2 II. MAJOR DRAINAGE BASINS..........................................................................................................................2 A. Major Basin Description..........................................................................................................................2 III. PROJECT DESCRIPTION................................................................................................................................3 IV. PROPOSED DRAINAGE FACILITIES...............................................................................................................4 A. General Concept .....................................................................................................................................4 B. Sub-Basin Description .............................................................................................................................5 C. Detention Basin/ Outlet Design ..............................................................................................................6 D. Water Quality Capture Volume (WQCV) Design.....................................................................................7 E. Low Impact Development (LID) Design...................................................................................................8 F. Drainage Easements/Maintenance Access.............................................................................................9 V. DRAINAGE DESIGN CRITERIA.......................................................................................................................9 A. Regulations..............................................................................................................................................9 B. Previous Studies......................................................................................................................................9 C. Four Step Process....................................................................................................................................9 D. Development Criteria Reference and Constraints ................................................................................10 E. Hydrological Criteria..............................................................................................................................11 A. Hydraulic Criteria ..................................................................................................................................11 VI. VARIANCE REQUESTS................................................................................................................................12 A. Floodplain Regulations Compliance......................................................................................................12 B. Modifications of Criteria .......................................................................................................................12 VII. EROSION CONTROL...................................................................................................................................12 VIII. CONCLUSIONS...........................................................................................................................................12 A. Compliance with Standards ..................................................................................................................12 B. Drainage Concept..................................................................................................................................12 REFERENCES......................................................................................................................................................13 APPENDICES Appendix A - Maps 1. Vicinity Map 2. FEMA FIRM Map 3. Fort Collins Flood Hazard Map 4. NRCS Soils Map 5. USFW Wetlands Mapper 6. ECS Report Feature Delineations Appendix B - Hydrologic Calculations 1. Development Imperviousness Assessment 2. Proposed Rational Calculations Appendix C - Hydraulic Calculations 1. Detention Pond Calculations-SWMM Model/ Volume Calculations 2. Water Quality and Low Impact Development (LID) Calculations and Exhibit 3. SDI Calculations Appendix D - Supporting Documents 1. Geotechnical Report 2. Foothills Basin Map 3. Pinecone PUD Drainage Plan 4. Ft. Collins IDF Curves 5. 2007 SWMM Basin Calculations Appendix E - Drainage Plans 1. 2007 Report Drainage Plan 2. Existing Drainage Plan 3. Proposed Drainage Plan 4. Water Quality Treatment Train P a g e 1 | 12 I. GENERAL LOCATION AND DESCRIPTION A. Location The Timberline Housing (hereafter referred to as “PROJECT”) site is located at 3008 South Timberline Road Fort Collins, Colorado 80525, adjacent to Timberline Church. The PROJECT lies within the Tract A and Lots 1, 2, and 5 of the Timberline Church P.U.D. specifically, in the West half of Section 29, Township 7 North, Range 68 West of the 6th Principal Meridian, City of Fort Collins, Larimer County, State of Colorado. The PROJECT is bound to the north and east by apartment complexes associated with the Rigden Farm development, to the south by the Foothills Channel and Rendezvous Trail, and to the west by Timberline Church and parking lot. Adjacent major roadways around the PROJECT site include South Timberline Road to the west and Custer Drive to the north. Refer to the vicinity map below and in the Appendix. Figure 1 - Vicinity Map, NTS B. Description of Property The PROJECT area site consists of approximately 10 acres of disturbed area. The existing site consists of native grasses, existing asphalt drives and parking areas, concrete sidewalks, an existing water quality and detention pond, and a drainage swale. The current Timberline Church property drains to the southeast and into a drainage swale or detention pond which then releases through two outlet structures into the Foothills Channel. The site drains through curb TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 2 | 12 and gutter, storm inlets and storm pipe, or overland flow. The PROJECT is located within the Foothills Master Drainage Basin. According to the “Geotechnical Engineering Report” produced by Terracon Consultants, dated May 5, 2021, the existing soils consist of silt or clay with varying amounts of sand and gravel over about 4 to 12 feet of sand and gravel. Bedrock was found at depths of approximately 17 to 21 feet below grade. Groundwater was encountered in all of the test borings at about 12 to 13 feet below existing site grades. A copy of the Geotechnical Report can be found in the Appendix. A USDA NRCS web soil survey of the PROJECT site states that the soils consist mostly of Nunn clay loam Type C Hydrologic Soils. The HSG C is the predominate soil type across the site and was used for runoff calculations. Soils with an HSG of C have a very slow infiltration rate when thoroughly wet and therefore have high runoff potential. A copy of the web soil survey is referenced in the Appendix. C. Floodplain Submittal Requirements The Flood Insurance Rate Map Number 08069C1000F Panel 1000 of 1420, dated December 19, 2006, shows that the proposed development is not located within the 100-year floodway area. The FEMA FIRMETTE Map is in Appendix A. According to the City of Ft Collins, the Foothills Channel is considered a High Risk Floodway. The floodway limits remain within the channel. Because the channel and existing detention pond are hydraulically connected, there is a possibility of back flow into the pond when the Foothills Channel WSEL is higher than the WSEL in the detention facility. A map showing the Ft. Collins Floodway is included in Appendix A. The proposed design is in accordance with the “City of Fort Collins Floodplain Review Checklist for Development Review Submittals.” II. MAJOR DRAINAGE BASINS A. Major Basin Description The PROJECT lies entirely within the Foothills Basin which is generally bound by Taft Hill, Ziegler, Horsetooth, and Drake Road. A Master Plan for the Foothills Basin was completed in 1981. In 1994, the Pinecone PUD Overall Drainage Plan divided the PROJECT site into two Major Basins, 59 and 60. In this report Basin 60 discharged into the channel undetained, while Basin 59 was slightly detained. Total releases from the site were limited to 97 cfs. In 1999, the site was further developed as outlined in the referenced Final Drainage Report. Water quality was provided my means of an extended detention facility. Improvements limited discharge from the detention facility to 20 cfs. The 2007 Final Drainage study included major developments to the site. This report utilized a “beat-the-peak” methodology to establish a new allowable site release of 82 cfs. The 1999 TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 3 | 12 Report also included an additional outfall to Foothills Channel and provided an overall site impervious design value based on future development plans. The PROJECT lies within several sub-basins developed in the 2007 Report. The affected basins (A2, A3, B3, B4, C2, D1, D2, and E) were eliminated and replaced with new basins (P1 thru P14, and D1). The proposed development has an overall site imperviousness (Basins 59 and 60) below the designed imperviousness values established within the 2007 report. Therefore, the “beat-the-peak” methodology utilized to design the detention pond remained applicable. Enhanced water quality features were integrated into the design as required by City of Fot. Collins water quality standards. Between the 2007 Report and the PROJECT, the accepted vertical datum has changed from NGVD29 to NAVD88. This results in a vertical increase of 3.19’ for all elevations referenced in prior reports. III. PROJECT DESCRIPTION The total PROJECT site is approximately 10 acres. The proposed development will include the construction of seven multifamily residential units, private drives and parking lots, and utility infrastructure necessary to service the proposed buildings. Additionally, drainage facilities designed to improve Stormwater Quality are proposed for the site in accordance with Chapter 7- Water Quality of the City of Fort Collins Stormwater Criteria Manual. The PROJECT design includes the modification of the extended detention pond as well as the drainage swale that provides detention and treats water quality for the 100-year storm for the added impervious area with the proposed PROJECT development. Various design criteria were changed throughout the development of the site. Where comparisons were made, like criteria was utilized to maintain consistency. The following assessments were performed: 1.Comparison of existing and proposed imperviousness: Criteria effective (surface impervious values) to the 2007 report were utilized when comparing the proposed project to the established design of the site. 2.Pipe, Inlet, and Conveyance capacities: current criteria with the Rational Method. 3.Proposed Water Quality and LID Design: current criteria with the Rational Method. 4.Assessment of the As-Build Detention Facility: current criteria with EPA SWMM. TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 4 | 12 IV. PROPOSED DRAINAGE FACILITIES A. General Concept The proposed drainage basins located on the PROJECT site consist of pavement, proposed building roof, landscaped areas, sidewalk and paved walking paths, paved parking lots, an extended detention pond and a drainage swale. The north quarter of the site drains to the drainage swale. The remainder of the site drains to the extended detention pond. About 75% of the PROJECT site drains to proposed LID systems before discharging into the detention pond and then discharging offsite into the Foothills Channel. The remaining 25% of the PROJECT site discharges directly to the existing detention pond where water quality is treated and stored before discharging offsite into the Foothills Channel. The balance of the existing site remaining undisturbed will maintain existing drainage ways to the existing detention pond prior to discharging offsite to the Foothills Channel. The proposed flow conditions are not expected to change drastically from existing conditions. The developed imperviousness of the site was compared to the originally designed imperviousness. To establish the existing condition, areas that are currently fully developed were assigned surface type areas (pavement, gravel, roof, or landscaping) based on current aerial imagery. Areas of future/proposed development (from the 2007 report) were assigned surface areas similar to the 2007 Report. These areas were compared to the design values tabulated in the original design report. It was concluded from this analysis that the overall site was originally calculated at a complete developed composite imperviousness of 75.5%. This is the imperviousness found in the 2007 report and utilized for the Water Quality Volume calculations. A composite imperviousness of 80% was utilized in the SWMM analysis of the detention pond in the 2007 report as well. Because portions of the proposed work assessed in the 2007 study, an updated “projected- developed” imperviousness was also calculated which accounted for the as-built condition of the site thus far, the current “projected-developed” developed composite imperviousness was calculated at 73.3%. A summary of these values is shown below in Table 1. To determine the developed composite imperviousness following completion of the PROJECT, modified basins were replaced with proposed basins and an overall imperviousness was calculated. The result was 72.5%, slightly below the current “projected-developed” state of 73.3% and well below the originally design values for water quality and detention of 75.5% and 80%. Detailed impervious calculations are included in Appendix B. TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 5 | 12 Table 1: Composite Site Imperviousness Summary Value Current Study 2007 Report Site Area (acres)32.76 32.82 Current Composite I (%)73.3 75.5 Imperviousness for Pond Design (%)80%80% B. Sub-Basin Description Existing Drainage In the existing condition, stormwater runoff generated on site is conveyed via overland flow to existing storm inlets or curb and gutter. The inlets then flow through existing RCP storm sewer which drains to both detention ponds. The project site that doesn’t flow into storm sewer flows as overland flow directly into the detention pond. Table 2 below provides a summary of the existing site imperviousness. Refer to Appendix E for the 2007 Drainage plan and the current Existing Drainage Plan. Peak flows for existing basins were not calculated as part of an existing site analysis. Table 2: Summary of Existing Basins Basin Design Point Area (Acres) % IMP. A1 A1 6.39 82 A2 A2 0.31 98 A3 A3 2.16 65 A4 A4 0.08 90 B1 B1 1.69 92 B2 B2 0.90 91 B3 B3 1.71 100 B4 B4 1.35 92 B5 B5 0.04 100 C1 C1 3.31 92 C2 C2 0.09 0 D1 D1 1.82 90 D2 D2 2.10 91 E1 E1 7.65 56 SITE COMPOSITE 32.82 73.3% Proposed Drainage Runoff generated from the proposed development is conveyed via overland flow towards storm inlets, curb and gutter, and roof drains before being conveyed to rain gardens, swales, underground filtration systems, or the existing detention ponds. The rain gardens, grass swales, and underground filtration systems will provide water quality treatment for the site and the detention ponds will provide detention and water quality treatment. Runoff from this site is ultimately tributary to the Foothills Channel. Refer to Appendix E for the Proposed Drainage Plan and basin delineation. See Table 3 for a summary of the proposed and existing basins. Note that the overall site imperviousness shown in the rational calculations is higher that the “projected-developed” imperviousness calculated above. As indicated above, the rational TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 6 | 12 analysis used the current value of 2% for landscaped areas where the overall site imperviousness assessment compared the conditions utilizing the 2007 report landscape impervious value of 0%. Table 3: Summary of Proposed Basins Basin Design Point Area (Acres) % IMP.C10 C100 Q10 (CFS) Q100 (CFS) P1 P1 0.16 89.8%0.82 0.91 0.46 1.48 P2 P2 0.95 58.1%0.54 0.72 1.74 6.82 P3 P3 1.16 75.8%0.66 0.79 2.61 9.15 P4 P4 0.20 53.9%0.49 0.68 0.32 1.34 P5 P5 0.20 69.2%0.63 0.78 0.42 1.52 P6 P6 0.46 80.8%0.74 0.86 1.14 3.90 P7 P7 0.83 83.5%0.75 0.86 2.11 7.09 P8 P8 1.62 3.3%0.17 0.52 0.88 7.84 P9 P9 0.44 70.8%0.60 0.73 0.90 3.22 P10 P10 0.72 76.2%0.71 0.84 1.74 6.04 P11 P11 1.11 49.7%0.50 0.71 1.87 7.81 P12 P12 0.44 71.0%0.63 0.77 0.94 3.36 P13 P13 0.33 99.1%0.89 0.96 1.00 3.16 P14 P14 0.44 99.3%0.89 0.96 1.31 4.16 A1 A1 6.39 82.2%0.77 0.88 13.04 43.40 A4 A4 0.08 90.0%0.75 0.83 0.20 0.64 B1 B1 1.69 91.9%0.84 0.92 4.05 13.05 B2 B2 0.90 90.9%0.83 0.92 2.36 7.73 B5 B5 0.04 100.0%0.90 0.96 0.12 0.38 C1 C1 3.31 91.7%0.84 0.92 7.88 25.50 C3 C3 1.82 90.3%0.75 0.83 4.17 13.27 C4 C4 2.10 90.8%0.76 0.84 4.93 16.43 D1 D1 7.40 56.5%0.57 0.76 7.98 30.69 OS1 OS1 3.02 90.2%0.83 0.91 6.72 21.22 OS2 OS2 1.41 90.2%0.83 0.91 3.14 9.92 SITE COMPOSITE 37.21 37.21 75.0%0.70 0.83 72.01 Basins in Italics are existing C. Detention Basin/ Outlet Design Per the 2007 report, the detention pond consists of three hydraulically connected sections: swale, north, and south ponds. For the remainder of this report, the term Pond will imply the composition of these three sections. Recently surveyed topography was used in the development of the existing pond’s stage-storage curve. The design approach (Beat the peak) of the detention pond swale was not changed. Minor infilling into the pond will occur with the PROJECT resulting in decreased storage capacity. This reduction is offset by enlarging the pond in different areas. The existing and proposed state- storage curves are shown in Appendix C along with a comparison of the two. The net result is a pond with slightly more storage capacity from the as-built condition. TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 7 | 12 The detention pond was analyzed using EPA SWMM Version 5.1. Basin information from the 2007 Report and current Fort Collins Drainage Criteria was utilized to develop sub catchments SWMM. Basins 59 and 60 were assumed to be at a fully developed imperviousness of 80%, exceeding the current PROJECT effective imperviousness. Both outlet structures were modeled in SWMM using recent survey information. Only detained release curves were developed for the outlet structures as culverts as the releases from the water quality orifice plates are minor compared to the outlet pipes. An updated peak storage volume and discharge was determined by routing inflows through the SWMM model. Detailed EPA SWMM documents are included in Appendix Table 4: Existing Pond Summary Table Value Current Study 2007 Report Detained Volume (acre-feet)2.003 3.700 Water Quality Volume (acre-feet)0.889 0.991 Peak Release (cfs)62.13 82 D. Water Quality Capture Volume (WQCV) Design The PROJECT site was designed using the Four Step Process outlined in the Fort Collins Stormwater Criteria Manual. The PROJECT site utilizes a combination of rain gardens (bioretention), grass swales, underground filtration systems, and extended detention basins to provide water quality treatment for the PROJECT. The PROJECT does not use any permeable pavers; therefore the 75/25 rule applies. 75% of the modified surfaces will be treated by approved LID Systems while the balance can be treated by standard practices. Most of the PROJECT area requires surface modification as both the surface type and flow patterns change. However, the improvements associated with the PROJECT within the private road and existing parking lot north of the PROJECT within Basins A1, B1, P13, and P14, consist of utility installation and pavement replacement. The flow patterns and surface types in these areas do not change. After discussion with City Staff, those basins are not included in the overall modified surface total and do not contribute to the 75/25 LID requirement. Approximately 75% of the site WQCV was treated using rain gardens, grass swales, or underground filters while the remaining 25% of the site was routed to the existing extended detention basin. A summary of the system distribution is shown below in Table 5. Refer to the Appendix C for detailed rain garden, grass swale, and new volume for the extended detention basin calculations. TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 8 | 12 Table 5: Water Quality Treatment Distribution System Type % Impervious Area WQCV (CF) EDB 18%35853 RAIN GARDEN A 18%891 RAIN GARDEN B 14%663 UG FILTRATION A 8%452 UG FILTRATION B 16%848 UG FILTRATION C 15%732 SWALE A 12%0 (In EDB) E. Low Impact Development (LID) Design A variety of Low-Impact-Design (“LID”) features were incorporated into the drainage design for this project. The following are descriptions of the LID features used in the PROJECT design: Bioretention (Rain Gardens): Rain gardens have been designed in accordance with the design and construction detailing for bioretention systems from the Fort Collins Stormwater Criteria Manual. There are 2 proposed rain gardens located throughout the PROJECT site. A 12-hour drain time was used when designing the rain gardens and all the rain gardens drain into the extended detention basins where it is then eventually discharged offsite. Several proposed drainage basins drain directly to the rain gardens via overland flow. No more than two drainage basins are directed to one rain garden. The rain gardens will be designed with one foot of water quality ponding depth. An inlet of weir will be provided in the rain gardens for an 100 Year overflow path that discharges directly into the extended detention basin. Underdrain piping will be provided within the rain garden as well as underdrain cleanouts as required in the Manual. Refer to Appendix C for detailed rain garden calculations. Grass Swale: Grass swales have been designed in accordance with the Grass Swale Best Management Practice Fact Sheet and Design Spreadsheet from the MANUAL. There is one proposed grass swale on the PROJECT site. This swale was designed using UDFCD UD-BMP spreadsheet and followed the CRITERIA and MANUAL. This facility will provide LID/Filtration treatment only, while the WQCV is still contained in the Extended Detention Basin. The site was graded to drain to a low point where the grass swale started and then drains freely into the existing drainage swale to the east with a slope of the grass lined swale at 0.50%. The Grass Swales will be densely vegetated trapezoidal channels with low-pitched side slopes and a relatively broad cross sections which will convey flow in a slow and shallow manner, thereby facilitating sedimentation and filtering while limiting erosion. Calculations for the grass swale is included in Appendix C. Underground Filtration: The underground stormwater BMPs have been designed in accordance with the design and construction detailing for underground infiltration/filtration systems from the Fort Collins Stormwater Criteria Manual. There are three proposed locations where these underground structures will be used throughout the PROJECT site. These were chosen because of space and grading constraints in the specific locations. StormTech chambers were used as a basis of design chosen due to their minimal cover requirements. Refer to Appendix C for detailed rain garden calculations. TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 9 | 12 Treatment Train: The use of a treatment train was used to provide multiple BMPs in series. The use of these LID techniques allows for more consistent treatment of runoff and provide redundancy if one component isn’t functioning as intended. A flow chart and table of the treatment train is provided in the Drainage Plans found in Appendix E. F. Drainage Easements/Maintenance Access All the drainage easements and maintenance accesses are shown on the drainage plans located in Appendix E. Drainage and utility easements will be executed with separate instruments following any replating. V. DRAINAGE DESIGN CRITERIA A. Regulations The drainage design of the project is in compliance with the following criteria: 1. Article VII, Stormwater Utility, City of Fort Collins Municipal Code, latest revision 2. City of Fort Collins Stormwater Criteria Manual, latest revision (“hereafter referred to as the “CRITERIA”). 3. “Urban Storm Drainage Criteria Manual” latest revision (hereafter referred to as the “MANUAL”). B. Previous Studies This drainage report has taken into account the results and recommendations of the previous PUD developed in 2007 for Timberline Church. It has also taken into account the results and recommendations of the previous drainage report developed as part of the 2007 PUD. C. Four Step Process The PROJECT site was designed to Minimize the Directly Connected Impervious Area (MDCIA) and follows the guidelines established in the City of Fort Collins Stormwater Criteria Manual and the MANUAL. The purposed of implementing this Four Step Process is to reduce runoff volumes, treating the WQCV, stabilize streams and implementing long-term source controls, and pertains to the management of smaller, more frequently occurring events. The Four Step Process used for our PROJECT is outlined below. Step 1: Employ Runoff Reduction Practices Currently the site contains open area as well as paved asphalt and concrete surfaces and a existing extended detention pond. The development of site landscaping throughout the site will help slow runoff and encourage infiltration where possible. Minimize Directly Connected Impervious Areas (MDCIA): Drainage design for the proposed residential apartment buildings will discharge roof drain downspouts across pervious landscaped areas to encourage stormwater infiltration where possible. TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 10 | 12 Extended detention pond: All of the proposed and existing runoff will continue to be routed to the existing extended detention basin which is grass lined with a small trickle channel in the center to collect the discharge from storm sewer into the extended detention ponds. Step 2: Implement BMPs that provide a WQCV with slow release. The WQCV for the proposed developed site will mostly be treated through proposed rain gardens, swales, and underground filters located throughout the PROJECT site and the remainder of the WQCV for the site will be treated in the existing extended detention pond. The rain gardens, underground filters, and extended detention ponds will release the WQCV at the rates required by the CRITERIA and MANUAL. The extended detention pond will provide water quality treatment as well as detention. Step 3: Stabilize Streams One of the major drainage channels for the Foothills Basin is located along the southeast side of the PROJECT site. Impacts on the downstream drainageway will be minimized by routing developed flows through LID Systems and controlling the release rate out of the pond to existing flows. Step 4: Implement Site Specific and Other Source Control BMP’s The proposed residential site development will implement Stormwater Management Plans including proper housekeeping practices and spill containment procedures as a separate document when the Final Drainage Report is submitted. Trash enclosures are shown on the construction plans and are labeled. All permeant features will be kept out of the detention basin features. D. Development Criteria Reference and Constraints As such, the PROJECT will provide 100-year detention per the approach approved in the 2007 Report and additional water quality treatment systems will be provided for the modified areas. TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 11 | 12 E. Hydrological Criteria The proposed drainage system is designed in accordance with the CRITERIA and the MANUAL. Per the CRITERIA, the 2-year and 100-year design storm events were as the minor and major storm events, respectively. The Rational Method was used to estimate the minor and major storm runoff generated in the proposed conditions. Impervious and runoff coefficients were obtained from the City of Fort Collins Stormwater Criteria Manual. Soils were classified as NRCS soil Type C for calculations. Refer to the Appendix B for detailed calculations and design aids. Table 6: Hydrologic Criteria Criteria Requirement Reference Design Storm Initial: 2-year-1-hour Major: 100-year-1-hour City of Fort Collins Stormwater Criteria Manual Rational Design Storm Rainfall Depths (inches) 2-Year: 0.82 100-Year: 2.86 Table 3.4-1 IDF Table for Rational Method, Stormwater Criteria Manual Storm Runoff Analysis Method Rational Water Quality WQCV Chapter 7, Stormwater Criteria Manual Detention Release LID Drain Time = 12hrs Extended Detention Basin= 40hrs City of Fort Collins Stormwater Criteria Manual Emergency Overflow 100 Year Peak Inflow City of Fort Collins Stormwater Criteria Manual Flood Plain Determination FEMA Firm Panel City of Fort Collins Flood Maps A. Hydraulic Criteria The required roof drains and pipes are designed to be routed throughout the PROJECT site will be designed and sized by the plumbing engineer. On-site flows will be captured by roof drains, storm inlets, or via overland flow into rain gardens or directly into the existing extended detention ponds. The major and minor storms were considered to have a 100-year and 2-year return interval, respectively. Supporting hydraulic calculations are included in the Appendix C. Table 7 Hydraulic Criteria Criteria Requirement Reference Conduit EGL Initial: within the pipe Major: below finished grade Conduit HGL Initial: within the pipe Major: 1 ft below finished grade Conduit Velocity Initial: 2 fps Major: 10 fps Public ROW Conduit Size Minimum for Public ROW: 15 inches/12 inches vertical for elliptical City of Fort Collins Stormwater Criteria Manual Storm Sewer Modeling StormCAD V8i Local Losses Method Pipe: Hazen Williams Structure: Darcy-Weisbach (K) HEC-22 Water Quality/ LID Design Rain Gardens, Swales, Filters, and Extended Detention Basins UDFCD, Volume 3 Ch 4 and City of Fort Collins Stormwater Criteria Manual TIMBERLINE ATTAINABLE HOUSING August 18, 2021 P a g e 12 | 12 VI. VARIANCE REQUESTS A. Floodplain Regulations Compliance No variances from the CRITERIA are requested at this time. B. Modifications of Criteria No MODIFICATIONS from the CRITERIA are requested at this time. VII. EROSION CONTROL The PROJECT will be designed in accordance with all Erosion Control Criteria and Erosion Control Materials and Erosion Control Plans will be submitted the Final Drainage Report VIII. CONCLUSIONS A. Compliance with Standards The Drainage Report for the Timberline Attainable Housing project has been prepared in compliance with the CRITERIA, MANUAL, and the City of Fort Collins Municipal Code, Section 3.4.3 Water Quality. The proposed drainage design is consistent with both existing and developed conditions. B. Drainage Concept Developed runoff will be collected and conveyed by a system of overland flow, roof drains, rain gardens, grass swales, proposed and existing storm sewer directed into the existing water quality and detention pond located in the eastern portion of the site. LID principles will improve the water quality for stormwater runoff from the developed site. Development of the site is not anticipated to adversely impact downstream properties or drainage facilities. H:\LOVATO\20.0336-Timberline Housing\ENG\DRAINAGE\Report\20_0336_May_20_2021_R0_DrainageRpt.docx REFERENCES A. “City of Fort Collins Municipal Code”, Latest revision B. “City of Fort Collins Stormwater Criteria Manual”, Latest revision C. “Geotechnical Engineering Report”, Terracon Consultants, Inc May 5, 2021. D. “Urban Drainage and Flood Control District Drainage Criteria Manual Vol. 1, 2 and 3”, Wright- McLauglin Engineers, Latest revision. E. “Final Drainage and Erosion Control Study for Timberline Church”, Northern Engineering Services, Inc., May 9, 2007 F. “Final Drainage and Erosion Control Study for Timberline Church”, Northern Engineering Services, Inc., December 3, 1999 G. “Overall Drainage Plan for the Pinecone ODP”, Lidstone & Anderson, March 7, 1995 APPENDIX A - MAPS 1000 ft N➤➤N © 2021 Google © 2021 Google © 2021 Google Foothill s C h a n n el Foothill s C h a n n el APPROXIMATE SITE LOCATION Timberline Church Rendezvous TrailRigden Farm National Flood Hazard Layer FIRMette 0 500 1,000 1,500 2,000250 Feet Ü SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT SPECIAL FLOOD HAZARD AREAS Without Base Flood Elevation (BFE) Zone A, V, A99 With BFE or DepthZone AE, AO, AH, VE, AR Regulatory Floodway 0.2% Annual Chance Flood Hazard, Areas of 1% annual chance flood with average depth less than one foot or with drainage areas of less than one square mileZone X Future Conditions 1% Annual Chance Flood HazardZone X Area with Reduced Flood Risk due to Levee. See Notes.Zone X Area with Flood Risk due to LeveeZone D NO SCREEN Area of Minimal Flood Hazard Zone X Area of Undetermined Flood HazardZone D Channel, Culvert, or Storm Sewer Levee, Dike, or Floodwall Cross Sections with 1% Annual Chance 17.5 Water Surface Elevation Coastal Transect Coastal Transect Baseline Profile Baseline Hydrographic Feature Base Flood Elevation Line (BFE) Effective LOMRs Limit of Study Jurisdiction Boundary Digital Data Available No Digital Data Available Unmapped This map complies with FEMA's standards for the use of digital flood maps if it is not void as described below. The basemap shown complies with FEMA's basemap accuracy standards The flood hazard information is derived directly from the authoritative NFHL web services provided by FEMA. This map was exported on 2/12/2021 at 4:14 PM and does not reflect changes or amendments subsequent to this date and time. The NFHL and effective information may change or become superseded by new data over time. This map image is void if the one or more of the following map elements do not appear: basemap imagery, flood zone labels, legend, scale bar, map creation date, community identifiers, FIRM panel number, and FIRM effective date. Map images for unmapped and unmodernized areas cannot be used for regulatory purposes. Legend OTHER AREAS OF FLOOD HAZARD OTHER AREAS GENERAL STRUCTURES OTHER FEATURES MAP PANELS 8 B 20.2 The pin displayed on the map is an approximate point selected by the user and does not represent an authoritative property location. 1:6,000 105°2'33"W 40°33'6"N 105°1'56"W 40°32'39"N Basemap: USGS National Map: Orthoimagery: Data refreshed October, 2020 4,514 752.3 Timberline Housing - Ft. Collins Flood Hazards This map is a user generated static output from the City of Fort Collins FCMaps Internet mapping site and is for reference only. Data layers that appear on this map may or may not be accurate, current, or otherwise reliable. City of Fort Collins - GIS 572.0 1: WGS_1984_Web_Mercator_Auxiliary_Sphere Feet572.00286.00 Notes Legend 3,430 City Floodplains City High Risk - Floodway City High Risk - 100 Year City Moderate Risk - 100 Year City Limits NearMap Logo United States Department of Agriculture A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Larimer County Area, ColoradoNatural Resources Conservation Service February 12, 2021 Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/ portal/nrcs/main/soils/health/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/? cid=nrcs142p2_053951). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey information. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require 2 alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. 3 Contents Preface....................................................................................................................2 Soil Map..................................................................................................................5 Soil Map................................................................................................................6 Legend..................................................................................................................7 Map Unit Legend..................................................................................................8 Map Unit Descriptions..........................................................................................8 Larimer County Area, Colorado......................................................................10 73—Nunn clay loam, 0 to 1 percent slopes.................................................10 74—Nunn clay loam, 1 to 3 percent slopes.................................................11 References............................................................................................................13 4 Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. 5 6 Custom Soil Resource Report Soil Map 448815044882304488310448839044884704488550448863044887104488790448815044882304488310448839044884704488550448863044887104488790496660 496740 496820 496900 496980 497060 497140 496660 496740 496820 496900 496980 497060 497140 40° 32' 59'' N 105° 2' 22'' W40° 32' 59'' N105° 2' 1'' W40° 32' 38'' N 105° 2' 22'' W40° 32' 38'' N 105° 2' 1'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 150 300 600 900 Feet 0 45 90 180 270 Meters Map Scale: 1:3,190 if printed on A portrait (8.5" x 11") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 15, Jun 9, 2020 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 11, 2018—Aug 12, 2018 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Custom Soil Resource Report 7 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 73 Nunn clay loam, 0 to 1 percent slopes 24.5 97.7% 74 Nunn clay loam, 1 to 3 percent slopes 0.6 2.3% Totals for Area of Interest 25.1 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, Custom Soil Resource Report 8 onsite investigation is needed to define and locate the soils and miscellaneous areas. An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. Custom Soil Resource Report 9 Larimer County Area, Colorado 73—Nunn clay loam, 0 to 1 percent slopes Map Unit Setting National map unit symbol: 2tlng Elevation: 4,100 to 5,700 feet Mean annual precipitation: 14 to 15 inches Mean annual air temperature: 48 to 52 degrees F Frost-free period: 135 to 152 days Farmland classification: Prime farmland if irrigated Map Unit Composition Nunn and similar soils:85 percent Minor components:15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Nunn Setting Landform:Terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Parent material:Pleistocene aged alluvium and/or eolian deposits Typical profile Ap - 0 to 6 inches: clay loam Bt1 - 6 to 10 inches: clay loam Bt2 - 10 to 26 inches: clay loam Btk - 26 to 31 inches: clay loam Bk1 - 31 to 47 inches: loam Bk2 - 47 to 80 inches: loam Properties and qualities Slope:0 to 1 percent Depth to restrictive feature:More than 80 inches Drainage class:Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat):Moderately low to moderately high (0.06 to 0.20 in/hr) Depth to water table:More than 80 inches Frequency of flooding:None Frequency of ponding:None Calcium carbonate, maximum content:7 percent Maximum salinity:Nonsaline (0.1 to 1.0 mmhos/cm) Sodium adsorption ratio, maximum:0.5 Available water capacity:High (about 9.1 inches) Interpretive groups Land capability classification (irrigated): 3e Land capability classification (nonirrigated): 4e Hydrologic Soil Group: C Ecological site: R067BY042CO - Clayey Plains Hydric soil rating: No Custom Soil Resource Report 10 Minor Components Heldt Percent of map unit:10 percent Landform:Terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Ecological site:R067BY042CO - Clayey Plains Hydric soil rating: No Wages Percent of map unit:5 percent Landform:Terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Ecological site:R067BY002CO - Loamy Plains Hydric soil rating: No 74—Nunn clay loam, 1 to 3 percent slopes Map Unit Setting National map unit symbol: 2tlpl Elevation: 3,900 to 5,840 feet Mean annual precipitation: 13 to 17 inches Mean annual air temperature: 50 to 54 degrees F Frost-free period: 135 to 160 days Farmland classification: Prime farmland if irrigated Map Unit Composition Nunn and similar soils:85 percent Minor components:15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Nunn Setting Landform:Terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Parent material:Pleistocene aged alluvium and/or eolian deposits Typical profile Ap - 0 to 9 inches: clay loam Bt - 9 to 13 inches: clay loam Btk - 13 to 25 inches: clay loam Bk1 - 25 to 38 inches: clay loam Bk2 - 38 to 80 inches: clay loam Custom Soil Resource Report 11 Properties and qualities Slope:1 to 3 percent Depth to restrictive feature:More than 80 inches Drainage class:Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat):Moderately low to moderately high (0.06 to 0.20 in/hr) Depth to water table:More than 80 inches Frequency of flooding:None Frequency of ponding:None Calcium carbonate, maximum content:7 percent Maximum salinity:Nonsaline to very slightly saline (0.1 to 2.0 mmhos/cm) Sodium adsorption ratio, maximum:0.5 Available water capacity:High (about 9.9 inches) Interpretive groups Land capability classification (irrigated): 2e Land capability classification (nonirrigated): 3e Hydrologic Soil Group: C Ecological site: R067BY042CO - Clayey Plains Hydric soil rating: No Minor Components Heldt Percent of map unit:10 percent Landform:Terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Ecological site:R067BY042CO - Clayey Plains Hydric soil rating: No Satanta Percent of map unit:5 percent Landform:Terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Ecological site:R067BY002CO - Loamy Plains Hydric soil rating: No Custom Soil Resource Report 12 References American Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition. American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00. Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31. Federal Register. July 13, 1994. Changes in hydric soils of the United States. Federal Register. September 18, 2002. Hydric soils of the United States. Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils in the United States. National Research Council. 1995. Wetlands: Characteristics and boundaries. Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/national/soils/?cid=nrcs142p2_054262 Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577 Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580 Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section. United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1. United States Department of Agriculture, Natural Resources Conservation Service. National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ home/?cid=nrcs142p2_053374 United States Department of Agriculture, Natural Resources Conservation Service. National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/ detail/national/landuse/rangepasture/?cid=stelprdb1043084 13 United States Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/soils/scientists/?cid=nrcs142p2_054242 United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/? cid=nrcs142p2_053624 United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. http:// www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf Custom Soil Resource Report 14 Timber line - Housing Source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus DS,USDA, USGS, AeroGRID, IGN, and the GIS User Community Wetlands Estuarine and Marine Deepwater Estuarine and Marine Wetland Freshwater Emergent Wetland Freshwater Forested/Shrub Wetland Freshwater Pond Lake Other Riverine June 1, 2021 0 0.1 0.20.05 mi 0 0.15 0.30.075 km 1:7,218 This page was produced by the NWI mapperNational Wetlands Inventory (NWI) This map is for general reference only. The US Fish and Wildlife Service is not responsible for the accuracy or currentness of the base data shown on this map. All wetlands related data should be used in accordance with the layer metadata found on the Wetlands Mapper web site. Timberline Housing Ecological Characterization Study A-3 Figure A-3. Field-delineated features. TIMBERLINE ATTAINABLE HOUSING June 2, 2021 APPENDI X B - HYDROLOGIC CALCULATIONS Project Timberline Housing Project #20.0336 Date 5/30/2021 Title Developed Imperviousness Assessment Surface C I Asphalt/Concrete 0.95 100 Gravel 0.50 40 Roofs 0.95 90 Sandy Soil 0.15 0 Clayey Soil 0.25 0 Basin Basin Area (SF)Basin Area (AC)Basin Area (AC)Composite % I Composite % I I * A I * A A1 278261 6.39 6.37 227688 231433 0 0 0 50573 46076 82 83.4 523 531 A2 13634 0.31 0.31 13329 13334 0 0 0 305 205 98 98.7 31 31 A3 94133 2.16 2.13 61028 65827 0 0 0 33106 27106 65 70.9 140 151 A4 3354 0.08 0.08 0 0 3354 3477 0 0 0 0 90 89.8 7 7 B1 73747 1.69 1.72 67649 63452 0 0 0 6098 11484 92 84.7 155 146 B2 39335 0.90 0.86 35676 34863 0 0 0 3659 2403 91 93.1 82 80 B3 74662 1.71 0.48 74357 20681 0 0 0 305 104 100 98.9 171 47 B4 58850 1.35 1.33 54276 54624 0 0 0 4574 3304 92 94.3 125 125 B5 1742 0.04 0.02 1742 0 0 901 0 0 0 0 100 93.1 4 2 C1 144096 3.31 3.33 131900 133180 0 0 0 12197 11723 92 91.8 303 306 C2 4095 0.09 1.27 0 52144 0 0 0 4095 3324 0 94.3 0 120 C3 79149 1.82 1.71 2526 0 76622 74461 0 0 0 0 90 90.0 164 154 C4 91520 2.10 2.17 7536 0 83984 94678 0 0 0 0 91 90.1 191 196 D1 333234 7.65 7.93 186175 217668 0 0 0 147059 127675 56 63.0 427 500 D2 38899 0.89 0.80 33672 33128 0 0 0 5227 1565 87 95.1 77 76 E1 98271 2.26 2.31 1002 2425 0 0 0 97269 98271 1 2.4 2 6 TOTAL 1426982 32.76 32.82 898556 922759 163960 173517 0 0 364467 333240 73.3 75.5 Notes Black values are area assessments based on current conditions and proposed future developments Red values are from the 2007 Design Report EXISTING BASINS (CURRENT CONDITIONS / DESIGN REPORT) Vegetated Area (SF) Gravel Area (SF) Surface Characteristics (From 2007 Report) Roof Area (SF) Asphalt/Concrete Area (SF) Project Timberline Housing Project #20.0336 Date 5/30/2021 Title Developed Imperviousness Assessment Surface C I Asphalt/Concrete 0.95 100 Gravel 0.50 40 Roofs 0.95 90 Sandy Soil 0.15 0 Clayey Soil 0.25 0 Basin Basin Area (SF) Basin Area (AC) Asphalt/Concrete Area (SF) Roof Area (SF) Gravel Area (SF) Vegetated Area (SF)Composite % I I * A P1 7144 0.16 6403 0 0 741 89.6 14.70 P2 41469 0.95 9845 12197 7579 11848 57.5 54.76 P3 50704 1.16 17468 16553 15028 1655 75.7 88.1 P4 8625 0.20 2352 0 5706 566 53.7 10.64 P5 8538 0.20 4443 348 2831 915 69.0 13.52 P6 19863 0.46 14026 1525 1481 2831 80.5 36.71 P7 36068 0.83 22477 6752 3746 3093 83.3 68.99 P8 70524 1.62 958 0 0 69565 1.4 2.2 P9 19297 0.44 0 11892 7405 0 70.8 31.37 P10 31494 0.72 22303 871 1960 6360 75.8 54.8 P11 48177 1.11 16379 6273 3659 21867 48.8 53.92 P12 19123 0.44 6403 4792 7100 828 70.9 31.12 P13 14418 0.33 14288 0 0 131 99.1 32.8 P14 18949 0.44 18818 0 0 131 99.3 43.2 D1 322126 7.40 177768 1525 0 142833 55.6 411.25 A1 278261 6.39 227688 0 0 50573 81.8 522.7 A2 A3 A4 3354 0.08 0 3354 0 0 90.0 6.93 B1 73747 1.69 67649 0 0 6098 91.7 155.3 B2 39335 0.90 35676 0 0 3659 90.7 81.9 B3 B4 B5 1742 0.04 1742 0 0 0 100.0 4 C1 144096 3.31 131900 0 0 12197 91.5 302.8 C2 C3 79149 1.82 2526 76622 0 0 90.3 164.11 C4 91520 2.10 7536 83984 0 0 90.8 190.82 D1 D2 E1 TOTAL 1427723 32.78 72.51 2376.64 PROPOSED BASINS BASIN ELIMINATED BASIN ELIMINATED BASIN ELIMINATED Surface Characteristics (From 2007 Report) *Values obtained from Fort Collins Stormwater Criteria Manual, December 2018. Table 3.2-2, Table 3.2-3, and Table 4.1-3 BASIN ELIMINATED BASIN ELIMINATED BASIN ELIMINATED BASIN ELIMINATED BASIN ELIMINATED PROJECT INFORMATION PROJECT NAME: PROJECT NO: DESIGN BY: REVIEWED BY: JURISDICTION: REPORT TYPE: DATE: C2 C5 C10 C100 % IMPERV 0.06 0.16 0.26 0.51 2% 0.73 0.75 0.77 0.83 90% 0.89 0.90 0.92 0.96 100% 0.73 0.75 0.77 0.83 90% 37.21 0.66 0.70 0.74 0.83 75.0% AREA (ACRES)C2 C5 C10 C100 0.02 0.06 0.16 0.26 0.51 2% 0.00 0.73 0.75 0.77 0.83 90% 0.15 0.89 0.90 0.92 0.96 100% 0.16 0.80 0.82 0.85 0.91 89.8% AREA (ACRES)C2 C5 C10 C100 0.28 0.73 0.75 0.77 0.83 90% 0.17 0.28 0.35 0.42 0.58 40% 0.23 0.89 0.90 0.92 0.96 100% 0.27 0.06 0.16 0.26 0.51 2% 0.95 0.49 0.54 0.60 0.72 58.1% AREA (ACRES)C2 C5 C10 C100 0.04 0.06 0.16 0.26 0.51 2% 0.38 0.73 0.75 0.77 0.83 90% 0.40 0.89 0.90 0.92 0.96 100% 0.35 0.28 0.35 0.42 0.58 40% 1.16 0.63 0.66 0.70 0.79 75.8% AREA (ACRES)C2 C5 C10 C100 0.01 0.06 0.16 0.26 0.51 2% 0.00 0.73 0.75 0.77 0.83 90% 0.05 0.89 0.90 0.92 0.96 100% 0.13 0.28 0.35 0.42 0.58 40% 0.20 0.43 0.49 0.55 0.68 53.9% AREA (ACRES)C2 C5 C10 C100 0.02 0.06 0.16 0.26 0.51 2% 0.01 0.73 0.75 0.77 0.83 90% 0.10 0.89 0.90 0.92 0.96 100% 0.07 0.28 0.35 0.42 0.58 40% 0.20 0.59 0.63 0.68 0.78 69.2% AREA (ACRES)C2 C5 C10 C100 0.04 0.73 0.75 0.77 0.83 90% 0.03 0.28 0.35 0.42 0.58 40% 0.07 0.06 0.16 0.26 0.51 2% 0.32 0.89 0.90 0.92 0.96 100% 0.46 0.71 0.74 0.78 0.86 80.8% PERCENT IMPERVIOUSNESS P4 LANDSCAPE ROOF ASPHALT/CONCRETE GRAVEL SUB-BASIN COMPOSITE ASPHALT/CONCRETE SUB-BASIN COMPOSITE SUB-BASIN SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS PERCENT IMPERVIOUSNESS P5 LANDSCAPE ROOF ASPHALT/CONCRETE GRAVEL SUB-BASIN COMPOSITE SUB-BASIN SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS SUB-BASIN SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS PERCENT IMPERVIOUSNESS P6 ROOF GRAVEL LANDSCAPE SUB-BASIN COMPOSITE SUB-BASIN SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS PERCENT IMPERVIOUSNESS P3 LANDSCAPE ROOF ASPHALT/CONCRETE GRAVEL SUB-BASIN COMPOSITE P2 ROOF GRAVEL ASPHALT/CONCRETE LANDSCAPE SUB-BASIN COMPOSITE SUB-BASIN ROOF ASPHALT/CONCRETE SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS PERCENT IMPERVIOUSNESS COMPOSITE RUNOFF COEFFICIENTS PERCENT IMPERVIOUSNESS ROOF LANDSCAPE Ft. Collins Preliminary 08/16/21 JURISDICTIONAL STANDARD Timberline Housing 20.0336 M. Bussell B. Nemec ASPHALT/CONCRETE P1 LANDSCAPE DRIVES AND WALKS TOTAL SITE COMPOSITE SUB-BASIN SURFACE CHARACTERISTICS 8/16/2021 13:44 COMPOSITE_C-VALUES H:\LOVATO\20.0336-Timberline Housing\ENG\DRAINAGE\Calculations\Rational Calculations (Non-UDFCD).xlsm AREA (ACRES)C2 C5 C10 C100 0.07 0.06 0.16 0.26 0.51 2% 0.16 0.73 0.75 0.77 0.83 90% 0.52 0.89 0.90 0.92 0.96 100% 0.09 0.28 0.35 0.42 0.58 40% 0.83 0.73 0.75 0.78 0.86 83.5% AREA (ACRES)C2 C5 C10 C100 1.60 0.06 0.16 0.26 0.51 2% 0.02 0.89 0.90 0.92 0.96 100% 0.00 0.73 0.75 0.77 0.83 90% 0.00 0.28 0.35 0.42 0.58 40% 1.62 0.07 0.17 0.27 0.52 3.3% AREA (ACRES)C2 C5 C10 C100 0.00 0.06 0.16 0.26 0.51 2% 0.00 0.89 0.90 0.92 0.96 100% 0.27 0.73 0.75 0.77 0.83 90% 0.17 0.28 0.35 0.42 0.58 40% 0.44 0.56 0.60 0.64 0.73 70.8% AREA (ACRES)C2 C5 C10 C100 0.02 0.73 0.75 0.77 0.83 90% 0.05 0.28 0.35 0.42 0.58 40% 0.51 0.89 0.90 0.92 0.96 100% 0.15 0.06 0.16 0.26 0.51 2% 0.72 0.68 0.71 0.75 0.84 76.2% AREA (ACRES)C2 C5 C10 C100 0.50 0.06 0.16 0.26 0.51 2% 0.14 0.73 0.75 0.77 0.83 90% 0.38 0.89 0.90 0.92 0.96 100% 0.08 0.28 0.35 0.42 0.58 40% 1.11 0.45 0.50 0.56 0.71 49.7% AREA (ACRES)C2 C5 C10 C100 0.02 0.06 0.16 0.26 0.51 2% 0.15 0.89 0.90 0.92 0.96 100% 0.11 0.73 0.75 0.77 0.83 90% 0.16 0.28 0.35 0.42 0.58 40% 0.44 0.59 0.63 0.67 0.77 71.0% AREA (ACRES)C2 C5 C10 C100 0.00 0.06 0.16 0.26 0.51 2% 0.00 0.73 0.75 0.77 0.83 90% 0.33 0.89 0.90 0.92 0.96 100% 0.00 0.28 0.35 0.42 0.58 40% 0.33 0.88 0.89 0.91 0.96 99.1% AREA (ACRES)C2 C5 C10 C100 0.00 0.06 0.16 0.26 0.51 2% 0.43 0.89 0.90 0.92 0.96 100% 0.44 0.88 0.89 0.92 0.96 99.3% SUB-BASIN COMPOSITE SUB-BASIN SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS PERCENT IMPERVIOUSNESS P7 LANDSCAPE ROOF ASPHALT/CONCRETE GRAVEL SUB-BASIN COMPOSITE SUB-BASIN SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS PERCENT IMPERVIOUSNESS P10 ROOF GRAVEL ASPHALT/CONCRETE LANDSCAPE SUB-BASIN COMPOSITE SUB-BASIN SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS PERCENT IMPERVIOUSNESS P9 LANDSCAPE ASPHALT/CONCRETE ROOF GRAVEL SUB-BASIN COMPOSITE PERCENT IMPERVIOUSNESS P12 LANDSCAPE ASPHALT/CONCRETE ROOF GRAVEL SUB-BASIN COMPOSITE SUB-BASIN SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS PERCENT IMPERVIOUSNESS P11 LANDSCAPE ROOF ASPHALT/CONCRETE GRAVEL SUB-BASIN COMPOSITE SUB-BASIN SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS PERCENT IMPERVIOUSNESS P13 LANDSCAPE ROOF ASPHALT/CONCRETE GRAVEL PERCENT IMPERVIOUSNESS P8 LANDSCAPE ASPHALT/CONCRETE ROOF GRAVEL SUB-BASIN SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS SUB-BASIN SURFACE CHARACTERISTICS SUB-BASIN COMPOSITE COMPOSITE RUNOFF COEFFICIENTS SUB-BASIN COMPOSITE SUB-BASIN SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS PERCENT IMPERVIOUSNESS P14 LANDSCAPE ASPHALT/CONCRETE 8/16/2021 13:44 COMPOSITE_C-VALUES H:\LOVATO\20.0336-Timberline Housing\ENG\DRAINAGE\Calculations\Rational Calculations (Non-UDFCD).xlsm AREA (ACRES)C2 C5 C10 C100 5.23 0.89 0.90 0.92 0.96 100% 1.16 0.06 0.16 0.26 0.51 2% 6.39 0.74 0.77 0.80 0.88 82.2% AREA (ACRES)C2 C5 C10 C100 0.08 0.73 0.75 0.77 0.83 90% 0.08 0.73 0.75 0.77 0.83 90.0% AREA (ACRES)C2 C5 C10 C100 1.55 0.89 0.90 0.92 0.96 100% 0.14 0.06 0.16 0.26 0.51 2% 1.69 0.82 0.84 0.87 0.92 91.9% AREA (ACRES)C2 C5 C10 C100 0.82 0.89 0.90 0.92 0.96 100% 0.08 0.06 0.16 0.26 0.51 2% 0.90 0.81 0.83 0.86 0.92 90.9% AREA (ACRES)C2 C5 C10 C100 0.04 0.89 0.90 0.92 0.96 100% 0.04 0.89 0.90 0.92 0.96 100.0% AREA (ACRES)C2 C5 C10 C100 3.03 0.89 0.90 0.92 0.96 100% 0.28 0.06 0.16 0.26 0.51 2% 3.31 0.82 0.84 0.86 0.92 91.7% AREA (ACRES)C2 C5 C10 C100 0.06 0.89 0.90 0.92 0.96 100% 1.76 0.73 0.75 0.77 0.83 90% 1.82 0.74 0.75 0.77 0.83 90.3% AREA (ACRES)C2 C5 C10 C100 0.17 0.89 0.90 0.92 0.96 100% 1.93 0.73 0.75 0.77 0.83 90% 2.10 0.74 0.76 0.78 0.84 90.8% SUB-BASIN COMPOSITE SUB-BASIN SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS PERCENT IMPERVIOUSNESS A1 ASPHALT/CONCRETE LANDSCAPE SUB-BASIN COMPOSITE SUB-BASIN SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS PERCENT IMPERVIOUSNESS A4 ROOF SUB-BASIN COMPOSITE SUB-BASIN SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS PERCENT IMPERVIOUSNESS B1 ASPHALT/CONCRETE LANDSCAPE SUB-BASIN COMPOSITE SUB-BASIN SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS PERCENT IMPERVIOUSNESS B2 ASPHALT/CONCRETE LANDSCAPE SUB-BASIN COMPOSITE SUB-BASIN SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS PERCENT IMPERVIOUSNESS B5 ASPHALT/CONCRETE SUB-BASIN COMPOSITE SUB-BASIN SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS PERCENT IMPERVIOUSNESS C1 ASPHALT/CONCRETE LANDSCAPE COMPOSITE RUNOFF COEFFICIENTS PERCENT IMPERVIOUSNESS C4 ASPHALT/CONCRETE ROOF SUB-BASIN COMPOSITE SUB-BASIN SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS PERCENT IMPERVIOUSNESS C3 ASPHALT/CONCRETE ROOF SUB-BASIN COMPOSITE SUB-BASIN SURFACE CHARACTERISTICS 8/16/2021 13:44 COMPOSITE_C-VALUES H:\LOVATO\20.0336-Timberline Housing\ENG\DRAINAGE\Calculations\Rational Calculations (Non-UDFCD).xlsm AREA (ACRES)C2 C5 C10 C100 4.08 0.89 0.90 0.92 0.96 100% 3.28 0.06 0.16 0.26 0.51 2% 0.04 0.73 0.75 0.77 0.83 90% 7.40 0.52 0.57 0.63 0.76 56.5% AREA (ACRES)C2 C5 C10 C100 2.72 0.89 0.90 0.92 0.96 100% 0.30 0.06 0.16 0.26 0.51 2% 3.02 0.81 0.83 0.85 0.91 90.2% AREA (ACRES)C2 C5 C10 C100 1.27 0.89 0.90 0.92 0.96 100% 0.14 0.06 0.16 0.26 0.51 2% 1.41 0.81 0.83 0.85 0.91 90.2% 37.21 0.66 0.70 0.74 0.83 75.0% OS2 ASPHALT/CONCRETE LANDSCAPE SUB-BASIN COMPOSITE SUB-BASIN SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS OS1 ASPHALT/CONCRETE LANDSCAPE SUB-BASIN COMPOSITE SUB-BASIN SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS PERCENT IMPERVIOUSNESS PERCENT IMPERVIOUSNESS SUB-BASIN SURFACE CHARACTERISTICS COMPOSITE RUNOFF COEFFICIENTS PERCENT IMPERVIOUSNESS D1 ASPHALT/CONCRETE LANDSCAPE ROOF SUB-BASIN COMPOSITE TOTAL SITE COMPOSITE 8/16/2021 13:44 COMPOSITE_C-VALUES H:\LOVATO\20.0336-Timberline Housing\ENG\DRAINAGE\Calculations\Rational Calculations (Non-UDFCD).xlsm CALCULATED BY:JOB NO: CHECKED BY:PROJECT: DATE: Is Project Urban?Yes AREA LENGTH SLOPE ti LENGTH SLOPE VEL.tt COMP.TOT. LENGTH SLOPE IMP tc tc ac ft ft/ft min ft ft/ft fps min tc ft ft/ft %First DP min (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17) P1 P1 0.82 0.16 90 0.0200 3.8 0.00 0.0 3.8 90.0 0.02 89.8%5.0 P2 P2 0.54 0.95 25 0.0300 3.5 100 0.0200 20 2.83 0.6 4.1 125.0 0.02 58.1%16.8 5.0 P3 P3 0.66 1.16 30 0.0300 3.0 60 0.0200 20 2.83 0.4 3.4 90.0 0.02 75.8%13.5 5.0 P4 P4 0.49 0.20 30 0.0300 4.2 270 0.0200 20 2.83 1.6 5.8 300.0 0.02 53.9%18.8 5.8 P5 P5 0.63 0.20 25 0.0300 3.0 100 0.0200 20 2.83 0.6 3.5 125.0 0.02 69.2%14.9 5.0 P6 P6 0.74 0.46 20 0.0250 2.1 75 0.0200 20 2.83 0.4 2.6 95.0 0.02 80.8%12.7 5.0 P7 P7 0.75 0.83 30 0.0300 2.4 115 0.0200 20 2.83 0.7 3.1 145.0 0.02 83.5%12.5 5.0 P8 P8 0.17 1.62 25 0.0250 6.2 0.00 0.0 6.2 25.0 0.03 3.3%6.2 P9 P9 0.60 0.44 30 0.2500 1.7 175 0.0200 20 2.83 1.0 2.7 205.0 0.05 70.8%15.1 5.0 P10 P10 0.71 0.72 30 0.0300 2.7 145 0.0200 20 2.83 0.9 3.5 175.0 0.02 76.2%13.9 5.0 P11 P11 0.50 1.11 30 0.0300 4.1 180 0.0250 20 3.16 0.9 5.1 210.0 0.03 49.7%18.7 5.1 P12 P12 0.63 0.44 25 0.0200 3.4 200 0.0200 20 2.83 1.2 4.6 225.0 0.02 71.0%15.2 5.0 P13 P13 0.89 0.33 15 0.0300 1.0 135 0.0200 20 2.83 0.8 1.8 150.0 0.02 99.1%9.8 5.0 P14 P14 0.89 0.44 20 0.0200 1.3 250 0.0100 20 2.00 2.1 3.4 270.0 0.01 99.3%10.9 5.0 A1 A1 0.77 6.39 150 0.0150 6.4 720 0.0210 20 2.90 4.1 10.5 870.0 0.02 82.2%16.1 10.5 A4 A2 0.75 0.08 25 0.0200 2.5 215 0.0100 20 2.00 1.8 4.3 240.0 0.01 90.0%12.4 5.0 B1 B1 0.84 1.69 360 0.0200 7.1 200 0.0100 20 2.00 1.7 8.8 560.0 0.02 91.9%11.9 8.8 B2 B2 0.83 0.90 200 0.0200 5.5 125 0.0100 20 2.00 1.0 6.5 325.0 0.02 90.9%11.5 6.5 B5 B5 0.90 0.04 10 0.0200 0.9 0.00 0.0 0.9 10.0 0.02 100.0%5.0 C1 C1 0.84 3.31 375 0.0250 6.7 255 0.0100 20 2.00 2.1 8.8 630.0 0.02 91.7%12.4 8.8 C3 C3 0.75 1.82 200 0.0200 7.1 0.00 0.0 7.1 200.0 0.02 90.3%7.1 C4 C4 0.76 2.10 200 0.0200 6.9 0.00 0.0 6.9 200.0 0.02 90.8%6.9 D1 D1 0.57 7.40 140 0.0140 10.1 1365 0.0100 20 2.00 11.4 21.5 1505.0 0.01 56.5%29.8 21.5 OS1 OS1 0.83 3.02 50 0.0200 2.7 900 0.0100 20 2.00 7.5 10.2 950.0 0.01 90.2%17.6 10.2 OS2 OS2 0.83 1.41 50 0.0200 2.7 900 0.0100 20 2.00 7.5 10.2 950.0 0.01 90.2%17.6 10.2 *Velocity (V) = CvSw0.5 TABLE 6-2 *Table 6-2, UDFCD (V.1), Chapter 6, Page 6-5 in which:Cv = Conveyance Coefficient (See Table Above) Sw = Watercourse Slope (ft/ft) BASIN DESIGN POINT C5 Cv DATA SUB-BASIN TIME (ti)(tt) Paved Areas and Shallow Paved Swales 20 Heavy Meadow 2.5 Tillage / Field Nearly Bare Ground 10 Grassed Waterway 15 5 Short Pasture and Lawns 7 Type of Land Surface Conveyance Coefficient, Cv 20.0336 Timberline Housing STANDARD FORM SF-2 (RATIONAL METHOD PROCEDURE) REMARKS tc CHECK (URBANIZED BASINS) M. Bussell B. Nemec 08/16/21 INITIAL/OVERLAND TIME OF CONCENTRATION SUMMARY TRAVEL TIME TOC 8/16/2021 13:44 H:\LOVATO\20.0336-Timberline Housing\ENG\DRAINAGE\Calculations\Rational Calculations (Non-UDFCD).xlsm CALCULATED BY:M. Bussell JOB NO:20.0336 CHECKED BY:B. Nemec PROJECT:Timberline Housing DATE:08/16/21 DESIGN STORM:2-YEAR ONE-HR PRECIP:0.82 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13) P1 P1 0.16 0.80 5.0 0.13 2.85 0.37 P2 P2 0.95 0.49 5.0 0.47 2.85 1.33 P3 P3 1.16 0.63 5.0 0.73 2.85 2.09 P4 P4 0.20 0.43 5.8 0.09 2.85 0.24 P5 P5 0.20 0.59 5.0 0.12 2.85 0.33 P6 P6 0.46 0.71 5.0 0.32 2.85 0.92 P7 P7 0.83 0.73 5.0 0.60 2.85 1.72 P8 P8 1.62 0.07 6.2 0.11 2.67 0.30 P9 P9 0.44 0.56 5.0 0.25 2.85 0.71 P10 P10 0.72 0.68 5.0 0.49 2.85 1.40 P11 P11 1.11 0.45 5.1 0.50 2.85 1.42 P12 P12 0.44 0.59 5.0 0.26 2.85 0.74 P13 P13 0.33 0.88 5.0 0.29 2.85 0.83 P14 P14 0.44 0.88 5.0 0.38 2.85 1.09 A1 A1 6.39 0.74 10.5 4.73 2.21 10.45 A4 A2 0.08 0.73 5.0 0.06 2.85 0.16 B1 B1 1.69 0.82 8.8 1.39 2.40 3.33 B2 B2 0.90 0.81 6.5 0.73 2.67 1.95 B5 B5 0.04 0.89 5.0 0.04 2.85 0.10 C1 C1 3.31 0.82 8.8 2.71 2.40 6.51 C3 C3 1.82 0.74 7.1 1.34 2.52 3.39 C4 C4 2.10 0.74 6.9 1.55 2.67 4.15 D1 D1 7.40 0.52 21.5 3.85 1.56 6.00 OS1 OS1 3.02 0.81 10.2 2.45 2.21 5.41 OS2 OS2 1.41 0.81 10.2 1.14 2.21 2.53 I.One-Hr Precipitation Values from NOAA Atlas 14 PFDS Return Period:2-YEAR 5-YEAR 10-YEAR 100-YEAR Depth In Inches:0.82 1.00 1.40 2.86 *Equation 5-1, UDFCD (V.1), Chapter 5, Page 5-9 *Rainfall Intensity:City of Fort Collins Stormwater Criteria Manual REMARKSAREA (AC) RUNOFF COEFF tc (MIN) BASIN DESIGN POINT DIRECT RUNOFF TOTAL RUNOFF tc (MIN) S(CxA) (AC) I (IN/HR) Q (CFS) STANDARD FORM SF-3 STORM DRAINAGE SYSTEM DESIGN (RATIONAL METHOD PROCEDURE) CxA (AC) I (IN/HR) Q (CFS) 2-YEAR 8/16/2021 13:44 H:\LOVATO\20.0336-Timberline Housing\ENG\DRAINAGE\Calculations\Rational Calculations (Non-UDFCD).xlsm CALCULATED BY:M. Bussell JOB NO:20.0336 CHECKED BY:B. Nemec PROJECT:Timberline Housing DATE:08/16/21 DESIGN STORM:100-YEAR ONE-HR PRECIP:2.86 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13) P1 P1 0.16 0.91 5.0 0.15 9.95 1.48 P2 P2 0.95 0.72 5.0 0.69 9.95 6.82 P3 P3 1.16 0.79 5.0 0.92 9.95 9.15 P4 P4 0.20 0.68 5.8 0.13 9.95 1.34 P5 P5 0.20 0.78 5.0 0.15 9.95 1.52 P6 P6 0.46 0.86 5.0 0.39 9.95 3.90 P7 P7 0.83 0.86 5.0 0.71 9.95 7.09 P8 P8 1.62 0.52 6.2 0.84 9.31 7.84 P9 P9 0.44 0.73 5.0 0.32 9.95 3.22 P10 P10 0.72 0.84 5.0 0.61 9.95 6.04 P11 P11 1.11 0.71 5.1 0.79 9.95 7.81 P12 P12 0.44 0.77 5.0 0.34 9.95 3.36 P13 P13 0.33 0.96 5.0 0.32 9.95 3.16 P14 P14 0.44 0.96 5.0 0.42 9.95 4.16 A1 A1 6.39 0.88 10.5 5.62 7.72 43.40 A4 A2 0.08 0.83 5.0 0.06 9.95 0.64 B1 B1 1.69 0.92 8.8 1.56 8.38 13.05 B2 B2 0.90 0.92 6.5 0.83 9.31 7.73 B5 B5 0.04 0.96 5.0 0.04 9.95 0.38 C1 C1 3.31 0.92 8.8 3.04 8.38 25.50 C3 C3 1.82 0.83 7.1 1.51 8.80 13.27 C4 C4 2.10 0.84 6.9 1.76 9.31 16.43 D1 D1 7.40 0.76 21.5 5.62 5.46 30.69 OS1 OS1 3.02 0.91 10.2 2.75 7.72 21.22 OS2 OS2 1.41 0.91 10.2 1.28 7.72 9.92 I.One-Hr Precipitation Values from NOAA Atlas 14 PFDS Return Period:2-YEAR 5-YEAR 10-YEAR 100-YEAR Depth In Inches:0.82 1.00 1.40 2.86 *Equation 5-1, UDFCD (V.1), Chapter 5, Page 5-9 *Rainfall Intensity:City of Fort Collins Stormwater Criteria Manual REMARKSAREA (AC) RUNOFF COEFF tc (MIN) STANDARD FORM SF-3 STORM DRAINAGE SYSTEM DESIGN (RATIONAL METHOD PROCEDURE) CxA (AC) I (IN/HR) Q (CFS) BASIN DESIGN POINT DIRECT RUNOFF TOTAL RUNOFF tc (MIN) S(CxA) (AC) I (IN/HR) Q (CFS) 100-YEAR 8/16/2021 13:44 H:\LOVATO\20.0336-Timberline Housing\ENG\DRAINAGE\Calculations\Rational Calculations (Non-UDFCD).xlsm PROJECT: JOB NO:01/20/00 DATE:08/16/21 DESIGN AREA %Q5 Q100 POINT (ACRES)IMP.(CFS)(CFS) P1 P1 0.16 89.8%0.82 0.91 0.46 1.48 P2 P2 0.95 58.1%0.54 0.72 1.74 6.82 P3 P3 1.16 75.8%0.66 0.79 2.61 9.15 P4 P4 0.20 53.9%0.49 0.68 0.32 1.34 P5 P5 0.20 69.2%0.63 0.78 0.42 1.52 P6 P6 0.46 80.8%0.74 0.86 1.14 3.90 P7 P7 0.83 83.5%0.75 0.86 2.11 7.09 P8 P8 1.62 3.3%0.17 0.52 0.88 7.84 P9 P9 0.44 70.8%0.60 0.73 0.90 3.22 P10 P10 0.72 76.2%0.71 0.84 1.74 6.04 P11 P11 1.11 49.7%0.50 0.71 1.87 7.81 P12 P12 0.44 71.0%0.63 0.77 0.94 3.36 P13 P13 0.33 99.1%0.89 0.96 1.00 3.16 P14 P14 0.44 99.3%0.89 0.96 1.31 4.16 A1 A1 6.39 82.2%0.77 0.88 13.04 43.40 A4 A2 0.08 90.0%0.75 0.83 0.20 0.64 B1 B1 1.69 91.9%0.84 0.92 4.05 13.05 B2 B2 0.90 90.9%0.83 0.92 2.36 7.73 B5 B5 0.04 100.0%0.90 0.96 0.12 0.38 C1 C1 3.31 91.7%0.84 0.92 7.88 25.50 C3 C3 1.82 90.3%0.75 0.83 4.17 13.27 C4 C4 2.10 90.8%0.76 0.84 4.93 16.43 D1 D1 7.40 56.5%0.57 0.76 7.98 30.69 OS1 OS1 3.02 90.2%0.83 0.91 6.72 21.22 OS2 OS2 1.41 90.2%0.83 0.91 3.14 9.92 37.21 75.0%0.70 0.83 72.01 249.13 Timberline Housing SITE COMPOSITE BASIN RUNOFF SUMMARY C5 C100 RUNOFF_SUMMARY 8/16/2021 13:44 H:\LOVATO\20.0336-Timberline Housing\ENG\DRAINAGE\Calculations\Rational Calculations (Non-UDFCD).xlsm TIMBERLINE ATTAINABLE HOUSING June 2, 2021 APPENDI X C - HYDRAULIC CAL CULATIONS Project Timberline Housing Project #20.0336 Date 8/16/2021 Title Existing Detention Pond Storage References none Formulas Volume (AF)Volume (CF)WSEL Depth Description 0.991 43167.96 4924.24 2.74 3.700 161172 4926.76 5.26 ELEV. (FT)DEPTH (FT)NORTH (SF)SOUTH (SF)AREA (SF) VOLUME (CF) ACCUM. VOL. (CF) ACCUM. VOL. (AF) 4921.5 0.0 0 0.0 0 0 0.000 4922.0 0.5 3775 3775.0 629 629 0.014 4923.0 1.5 15758 15758.0 9082 9711 0.223 4924.0 2.5 0 33753 33753.0 24191 33902 0.778 4925.0 3.5 711 41328 42039.0 37820 71723 1.647 4926.0 4.5 3199 47801 51000.1 46447 118170 2.713 4927.0 5.5 7611 54443 62054.0 56437 174607 4.008 Notes none DETENTION POND STORAGE CAPACITY Ac-Ft @ 100-year Ac-Ft @ WQ 4921.0 4922.0 4923.0 4924.0 4925.0 4926.0 4927.0 4928.0 0.000 0.500 1.000 1.500 2.000 2.500 3.000 3.500 4.000 4.500ELEV(FT)VOL (AC-FT) Storage-WSEL Curve Water Level Ac-Ft @ WQ Ac-Ft @ 100-year 𝑉=ℎ 3 𝐴1 +𝐴2 +𝐴1 𝐴2 Page 1 of 3 H:\LOVATO\20.0336-Timberline Housing\ENG\DRAINAGE\Calculations\Detention Ponds\Stage-Storage.xlsx/Stage- Storage.xlsx Project Timberline Housing Project #20.0336 Date 8/16/2021 Title Proposed Detention Pond Storage References none Formulas Volume (AF)Volume (CF)WSEL Depth Description 0.823 35850 4924.00 2.50 2.003 87248 4925.34 3.84 ELEV. (FT)DEPTH (FT)NORTH (SF)SOUTH (SF)AREA (SF) VOLUME (CF) ACCUM. VOL. (CF) ACCUM. VOL. (AF) 4921.5 0.0 0 0.0 0 0 0.000 4922.0 0.5 6313 6313.0 1052 1052 0.024 4923.0 1.5 16604 16604.0 11052 12104 0.278 4924.0 2.5 0 31771 31771.0 23781 35885 0.824 4925.0 3.5 1510 38551 40061.0 35836 71721 1.646 4926.0 4.5 6978 44128 51106.0 45472 117192 2.690 4927.0 5.5 17040 50605 67645.0 59183 176375 4.049 Notes none DETENTION POND STORAGE CAPACITY Ac-Ft @ WQ Ac-Ft @ 100-year 4921.0 4922.0 4923.0 4924.0 4925.0 4926.0 4927.0 4928.0 0.000 0.500 1.000 1.500 2.000 2.500 3.000 3.500 4.000 4.500ELEV(FT)VOL (AC-FT) Storage-WSEL Curve Water Level Ac-Ft @ WQ Ac-Ft @ 100-year 𝑉=ℎ 3 𝐴1 +𝐴2 +𝐴1 𝐴2 Page 2 of 3 H:\LOVATO\20.0336-Timberline Housing\ENG\DRAINAGE\Calculations\Detention Ponds\Stage-Storage.xlsx/Stage- Storage.xlsx Project Timberline Housing Project #20.0336 Date 8/16/2021 Title Detention Pond Storage Comparison ELEV. (FT)EX AREA (SF)EX VOL. (AF)PROP AREA (SF) PROP VOL. (AF)Δ AREA (SF)Δ VOL. (AF)Δ VOL. (CF) 4921.5 0 0.000 0 0.000 0 0.000 0 4922.0 3775 0.014 6313 0.024 2538 -0.010 -423 4923.0 15758 0.223 16604 0.278 846 -0.055 -2393 4924.0 33753 0.778 31771 0.824 -1982 -0.046 -1983 4925.0 42039 1.647 40061 1.646 -1978 0.000 2 4926.0 51000 2.713 51106 2.690 106 0.022 978 4927.0 62054 4.008 67645 4.049 5591 -0.041 -1768 DETENTION POND CHANGE 4921.0 4922.0 4923.0 4924.0 4925.0 4926.0 4927.0 4928.0 0.000 0.500 1.000 1.500 2.000 2.500 3.000 3.500 4.000 4.500ELEV(FT)VOL (AC-FT) Proposed/Existing Pond Comparison Existing Pond Proposed Culvert Calculator Report North Culvert h:\...\calculations\culverts\outlet culverts.cvm 06/01/21 15:43:19 Martin/Martin Consulting Engineers © Bentley Systems, Inc. Haestad Methods Solution Center Watertown, CT 06795 USA +1-203-755-1666 Project Engineer: BNemec CulvertMaster v3.3 [03.03.00.04] Page 1 Solve For: Discharge Culvert Summary Allowable HW Elevation 10.00 ft Headwater Depth/Height 0.00 Computed Headwater Elevation 4,921.39 ft Discharge 0.00 cfs Inlet Control HW Elev. 4,921.39 ft Tailwater Elevation 0.00 ft Outlet Control HW Elev. 4,921.39 ft Control Type Inlet Control Grades Upstream Invert 4,921.39 ft Downstream Invert 4,916.91 ft Length 84.00 ft Constructed Slope 0.000952 ft/ft Hydraulic Profile Profile Dry Depth, Downstream 0.00 ft Slope Type Dry Normal Depth 0.00 ft Flow Regime Subcritical Critical Depth 0.00 ft Velocity Downstream 0.00 ft/s Critical Slope 0.000000 ft/ft Section Section Shape Circular Mannings Coefficient 0.013 Section Material Concrete Span 2.00 ft Section Size 24 inch Rise 2.00 ft Number Sections 1 Outlet Control Properties Outlet Control HW Elev. 4,921.39 ft Upstream Velocity Head 0.00 ft Ke 0.50 Entrance Loss 0.00 ft Inlet Control Properties Inlet Control HW Elev. 4,921.39 ft Flow Control N/A Inlet Type Square edge w/headwall Area Full 3.1 ft² K 0.00980 HDS 5 Chart 1 M 2.00000 HDS 5 Scale 1 C 0.03980 Equation Form 1 Y 0.67000 Culvert Calculator Report South Culvert h:\...\calculations\culverts\outlet culverts.cvm 06/01/21 15:43:19 Martin/Martin Consulting Engineers © Bentley Systems, Inc. Haestad Methods Solution Center Watertown, CT 06795 USA +1-203-755-1666 Project Engineer: BNemec CulvertMaster v3.3 [03.03.00.04] Page 2 Solve For: Headwater Elevation Culvert Summary Allowable HW Elevation 10.00 ft Headwater Depth/Height 3.39 Computed Headwater Elevation 4,931.29 ft Discharge 100.00 cfs Inlet Control HW Elev. 4,931.29 ft Tailwater Elevation 0.00 ft Outlet Control HW Elev. 4,930.83 ft Control Type Inlet Control Grades Upstream Invert 4,921.11 ft Downstream Invert 4,921.31 ft Length 84.00 ft Constructed Slope -0.002381 ft/ft Hydraulic Profile Profile CompositeA2PressureProfile Depth, Downstream 2.90 ft Slope Type Adverse Normal Depth N/A ft Flow Regime Subcritical Critical Depth 2.90 ft Velocity Downstream 14.30 ft/s Critical Slope 0.019679 ft/ft Section Section Shape Circular Mannings Coefficient 0.013 Section Material Concrete Span 3.00 ft Section Size 36 inch Rise 3.00 ft Number Sections 1 Outlet Control Properties Outlet Control HW Elev. 4,930.83 ft Upstream Velocity Head 3.11 ft Ke 0.50 Entrance Loss 1.56 ft Inlet Control Properties Inlet Control HW Elev. 4,931.29 ft Flow Control N/A Inlet Type Square edge w/headwall Area Full 7.1 ft² K 0.00980 HDS 5 Chart 1 M 2.00000 HDS 5 Scale 1 C 0.03980 Equation Form 1 Y 0.67000 Project Timberline Housing Project #20.0336 Date 8/16/2021 Title Existing Outlet Culvert Rating Curves POND OUTLET CULVERT RATINGS 0.00 10.00 20.00 30.00 40.00 50.00 60.00 0.00 1.00 2.00 3.00 4.00 5.00 6.00Discharge (cfs)Depth (ft) Outlet Rating Curves NORTH CULVERT SOUTH CULVERT Project Timberline Housing Project #20.0336 Date 6/1/2021 Title SWMM Rain Gage Time Date Time Intensity 100-Year (in/hr) 5 1/1/2005 0:05 1.00 10 1/1/2005 0:10 1.14 15 1/1/2005 0:15 1.33 20 1/1/2005 0:20 2.23 25 1/1/2005 0:25 2.84 30 1/1/2005 0:30 5.49 35 1/1/2005 0:35 9.95 40 1/1/2005 0:40 4.12 45 1/1/2005 0:45 2.48 50 1/1/2005 0:50 1.46 55 1/1/2005 0:55 1.22 60 1/1/2005 1:00 1.06 65 1/1/2005 1:05 1.00 70 1/1/2005 1:10 0.95 75 1/1/2005 1:15 0.91 80 1/1/2005 1:20 0.87 85 1/1/2005 1:25 0.84 90 1/1/2005 1:30 0.81 95 1/1/2005 1:35 0.78 100 1/1/2005 1:40 0.75 105 1/1/2005 1:45 0.73 110 1/1/2005 1:50 0.71 115 1/1/2005 1:55 0.69 120 1/1/2005 2:00 0.67 Notes None DESIGN RAIN GAGE (FT COLLINS) EPA SWMM INP FILE [TITLE] ;;Project Title/Notes TIMBERLINE HOUSING DETENTION POND ANALYSIS [OPTIONS] ;;Option Value FLOW_UNITS CFS INFILTRATION HORTON FLOW_ROUTING KINWAVE LINK_OFFSETS ELEVATION MIN_SLOPE .1 ALLOW_PONDING NO SKIP_STEADY_STATE NO START_DATE 01/01/2005 START_TIME 00:00:00 REPORT_START_DATE 01/01/2005 REPORT_START_TIME 00:00:00 END_DATE 01/04/2005 END_TIME 00:00:00 SWEEP_START 01/01 SWEEP_END 12/31 DRY_DAYS 0 REPORT_STEP 00:05:00 WET_STEP 00:05:00 DRY_STEP 00:05:00 ROUTING_STEP 0:00:30 INERTIAL_DAMPING PARTIAL NORMAL_FLOW_LIMITED BOTH FORCE_MAIN_EQUATION H -W VARIABLE_STEP 0.75 LENGTHENING_STEP 0 EPA SWMM INP FILE MIN_SURFAREA 12.566 MAX_TRIALS 8 HEAD_TOLERANCE 0.005 SYS_FLOW_TOL 5 LAT_FLOW_TOL 5 MINIMUM_STEP 0.5 THREADS 1 [EVAPORATION] ;;Data Source Parameters ;;-------------- ---------------- CONSTANT 0.0 DRY_ONLY NO [RAINGAGES] ;;Name Format Interval SCF Source ;;-------------- --------- ------ ------ ---------- RAIN_GAGE INTENSITY 0:05 1.0 TIMESERIES FT_C OLLINS [SUBCATCHMENTS] ;;Name Rain Gage Outlet Area %Imperv Width %Slope CurbLen SnowPack ;;-------------- ---------------- ---------------- -------- -------- -------- -------- -------- ---------------- BASIN_59 RAIN_GAGE DETENTION_POND 20.7 80 1500 .006 0 BASIN_60 RAIN_GAGE DETENTION_POND 12.1 80 1408 .006 0 [SUBAREAS] ;;Subcatchment N-Imperv N-Perv S-Imperv S-Perv PctZero RouteTo PctRouted ;;-------------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- BASIN_59 0.016 .25 .1 .3 1 OUTLET BASIN_60 0.016 .25 .1 .3 1 OUTLET [INFILTRATION] ;;Subcatchment MaxRate MinRate Decay DryTime MaxInfil ;;-------------- ---------- ---------- ---------- ---------- ---------- EPA SWMM INP FILE BASIN_59 .51 .5 .0018 7 0 BASIN_60 .51 .5 0.0018 7 0 [OUTFALLS] ;;Name Elevation Type Stage Data Gated Route To ;;-------------- ---------- ---------- ---------------- -------- ---------------- SOUTH_OUTFALL 4921.31 FREE NO NORTH_OUTFALL 4916.91 FREE NO [STORAGE] ;;Name Elev. MaxDepth InitDepth Shape Curve Name/Params N/A Fevap Psi Ksat I MD ;;-------------- -------- ---------- ----------- ---------- ---------------------------- -------- -------- -------- -------- DETENTION_POND 4921.5 7 0 TABULAR DETENTION_POND 0 0 [OUTLETS] ;;Name From Node To Node Offset Type QTable/Qcoeff Qexpon Gated ;;-------------- ---------------- ---------------- ---------- --------------- ---------------- ---------- -------- SOUTH_OUTLET_PIPE DETENTION_POND SOUTH_OUTFALL * TABULAR/DEPTH SOUTH_OUTLET NO NORTH_OUTLET_PIPE DETENTION_POND NORTH_OUTFALL * TABULAR/DEPTH NORTH_OUTLET NO [CURVES] ;;Name Type X-Value Y-Value ;;-------------- ---------- ---------- ---------- SOUTH_OUTLET Rating 0.00 0.00 SOUTH_OUTLET 0.10 0.02 SOUTH_OUTLET 0.20 0.02 SOUTH_OUTLET 0.30 0.04 SOUTH_OUTLET 0.40 0.04 SOUTH_OUTLET 0.50 0.06 SOUTH_OUTLET 0.60 0.08 SOUTH_OUTLET 0.70 0.10 SOUTH_OUTLET 0.80 0.12 SOUTH_OUTLET 0.90 0.12 SOUTH_OUTLET 1.00 0.16 EPA SWMM INP FILE SOUTH_OUTLET 1.10 0.18 SOUTH_OUTLET 1.20 0.20 SOUTH_OUTLET 1.30 0.24 SOUTH_OUTLET 1.40 0.24 SOUTH_OUTLET 1.50 0.26 SOUTH_OUTLET 1.60 0.30 SOUTH_OUTLET 1.70 0.32 SOUTH_OUTLET 1.80 0.34 SOUTH_OUTLET 1.90 0.38 SOUTH_OUTLET 2.00 0.42 SOUTH_OUTLET 2.10 0.44 SOUTH_OUTLET 2.20 0.46 SOUTH_OUTLET 2.30 0.52 SOUTH_OUTLET 2.40 0.52 SOUTH_OUTLET 2.50 0.52 SOUTH_OUTLET 2.60 0.58 SOUTH_OUTLET 2.70 0.58 SOUTH_OUTLET 2.80 0.60 SOUTH_OUTLET 2.90 0.64 SOUTH_OUTLET 3.00 0.64 SOUTH_OUTLET 3.10 0.64 SOUTH_OUTLET 3.20 0.68 SOUTH_OUTLET 3.30 0.70 SOUTH_OUTLET 3.40 0.70 SOUTH_OUTLET 3.50 0.72 SOUTH_OUTLET 3.60 0.74 SOUTH_OUTLET 3.70 38.71 SOUTH_OUTLET 3.80 40.21 SOUTH_OUTLET 3.90 41.63 SOUTH_OUTLET 4.00 42.99 SOUTH_OUTLET 4.10 44.34 SOUTH_OUTLET 4.20 45.69 SOUTH_OUTLET 4.30 47.02 SOUTH_OUTLET 4.40 48.31 EPA SWMM INP FILE SOUTH_OUTLET 4.50 49.60 SOUTH_OUTLET 4.60 50.88 SOUTH_OUTLET 4.70 52.12 SOUTH_OUTLET 4.80 53.36 SOUTH_OUTLET 4.90 54.59 SOUTH_OUTLET 5.00 55.78 SOUTH_OUTLET 5.10 56.04 SOUTH_OUTLET 5.20 57.21 SOUTH_OUTLET 5.30 58.36 SOUTH_OUTLET 5.40 59.49 SOUTH_OUTLET 5.50 60.62 SOUTH_OUTLET 5.60 61.73 SOUTH_OUTLET 5.70 62.83 SOUTH_OUTLET 5.80 63.92 SOUTH_OUTLET 5.90 65.00 SOUTH_OUTLET 6.00 66.06 SOUTH_OUTLET 6.10 67.11 SOUTH_OUTLET 6.20 68.15 SOUTH_OUTLET 6.30 69.18 SOUTH_OUTLET 6.40 70.20 SOUTH_OUTLET 6.50 71.21 SOUTH_OUTLET 6.60 72.21 SOUTH_OUTLET 6.70 73.20 SOUTH_OUTLET 6.80 74.18 SOUTH_OUTLET 6.90 75.15 SOUTH_OUTLET 7.00 76.11 SOUTH_OUTLET 7.10 77.06 SOUTH_OUTLET 7.20 78.00 SOUTH_OUTLET 7.30 78.94 SOUTH_OUTLET 7.40 79.83 SOUTH_OUTLET 7.50 80.61 SOUTH_OUTLET 7.60 81.39 SOUTH_OUTLET 7.70 82.16 SOUTH_OUTLET 7.80 82.92 EPA SWMM INP FILE SOUTH_OUTLET 7.90 83.67 SOUTH_OUTLET 8.00 84.42 SOUTH_OUTLET 8.10 85.16 SOUTH_OUTLET 8.20 85.89 SOUTH_OUTLET 8.30 86.62 SOUTH_OUTLET 8.40 87.34 SOUTH_OUTLET 8.50 88.06 SOUTH_OUTLET 8.60 88.77 SOUTH_OUTLET 8.70 89.47 SOUTH_OUTLET 8.80 90.17 SOUTH_OUTLET 8.90 90.86 SOUTH_OUTLET 9.00 91.55 SOUTH_OUTLET 9.10 92.23 SOUTH_OUTLET 9.20 92.91 SOUTH_OUTLET 9.30 93.59 SOUTH_OUTLET 9.40 94.25 SOUTH_OUTLET 9.50 94.92 SOUTH_OUTLET 9.60 95.58 SOUTH_OUTLET 9.70 96.23 SOUTH_OUTLET 9.80 96.88 SOUTH_OUTLET 9.90 97.53 SOUTH_OUTLET 10.00 98.17 ; NORTH_OUTLET Rating 0.00 0.00 NORTH_OUTLET 0.10 0.00 NORTH_OUTLET 0.20 0.00 NORTH_OUTLET 0.30 0.00 NORTH_OUTLET 0.40 0.00 NORTH_OUTLET 0.50 0.00 NORTH_OUTLET 0.60 0.00 NORTH_OUTLET 0.70 0.00 NORTH_OUTLET 0.80 0.00 NORTH_OUTLET 0.90 0.00 NORTH_OUTLET 1.00 0.00 EPA SWMM INP FILE NORTH_OUTLET 1.10 0.00 NORTH_OUTLET 1.20 0.00 NORTH_OUTLET 1.30 0.00 NORTH_OUTLET 1.40 0.00 NORTH_OUTLET 1.50 0.00 NORTH_OUTLET 1.60 0.00 NORTH_OUTLET 1.70 0.00 NORTH_OUTLET 1.80 0.00 NORTH_OUTLET 1.90 0.00 NORTH_OUTLET 2.00 0.00 NORTH_OUTLET 2.10 0.00 NORTH_OUTLET 2.20 0.00 NORTH_OUTLET 2.30 0.00 NORTH_OUTLET 2.40 0.00 NORTH_OUTLET 2.50 0.00 NORTH_OUTLET 2.60 0.00 NORTH_OUTLET 2.70 0.00 NORTH_OUTLET 2.80 0.00 NORTH_OUTLET 2.90 0.00 NORTH_OUTLET 3.00 0.00 NORTH_OUTLET 3.10 0.00 NORTH_OUTLET 3.20 0.00 NORTH_OUTLET 3.30 0.00 NORTH_OUTLET 3.40 0.00 NORTH_OUTLET 3.50 0.00 NORTH_OUTLET 3.60 0.00 NORTH_OUTLET 3.70 19.91 NORTH_OUTLET 3.80 20.45 NORTH_OUTLET 3.90 20.98 NORTH_OUTLET 4.00 21.50 NORTH_OUTLET 4.10 22.02 NORTH_OUTLET 4.20 22.53 NORTH_OUTLET 4.30 23.02 NORTH_OUTLET 4.40 23.52 EPA SWMM INP FILE NORTH_OUTLET 4.50 24.00 NORTH_OUTLET 4.60 24.48 NORTH_OUTLET 4.70 24.95 NORTH_OUTLET 4.80 25.42 NORTH_OUTLET 4.90 25.88 NORTH_OUTLET 5.00 26.33 NORTH_OUTLET 5.10 26.78 NORTH_OUTLET 5.20 27.22 NORTH_OUTLET 5.30 27.66 NORTH_OUTLET 5.40 28.09 NORTH_OUTLET 5.50 28.51 NORTH_OUTLET 5.60 28.93 NORTH_OUTLET 5.70 29.35 NORTH_OUTLET 5.80 29.76 NORTH_OUTLET 5.90 30.16 NORTH_OUTLET 6.00 30.56 NORTH_OUTLET 6.10 30.96 NORTH_OUTLET 6.20 31.35 NORTH_OUTLET 6.30 31.74 NORTH_OUTLET 6.40 32.12 NORTH_OUTLET 6.50 32.50 NORTH_OUTLET 6.60 32.88 NORTH_OUTLET 6.70 33.25 NORTH_OUTLET 6.80 33.62 NORTH_OUTLET 6.90 33.98 NORTH_OUTLET 7.00 34.34 NORTH_OUTLET 7.10 34.70 NORTH_OUTLET 7.20 35.05 NORTH_OUTLET 7.30 35.40 NORTH_OUTLET 7.40 35.75 NORTH_OUTLET 7.50 36.10 NORTH_OUTLET 7.60 36.44 NORTH_OUTLET 7.70 36.77 NORTH_OUTLET 7.80 37.11 EPA SWMM INP FILE NORTH_OUTLET 7.90 37.44 NORTH_OUTLET 8.00 37.77 NORTH_OUTLET 8.10 38.10 NORTH_OUTLET 8.20 38.42 NORTH_OUTLET 8.30 38.74 NORTH_OUTLET 8.40 39.06 NORTH_OUTLET 8.50 39.38 NORTH_OUTLET 8.60 39.69 NORTH_OUTLET 8.70 40.01 NORTH_OUTLET 8.80 40.31 NORTH_OUTLET 8.90 40.62 NORTH_OUTLET 9.00 40.93 NORTH_OUTLET 9.10 41.23 NORTH_OUTLET 9.20 41.53 NORTH_OUTLET 9.30 41.83 NORTH_OUTLET 9.40 42.12 NORTH_OUTLET 9.50 42.42 NORTH_OUTLET 9.60 42.71 NORTH_OUTLET 9.70 43.00 NORTH_OUTLET 9.80 43.29 NORTH_OUTLET 9.90 43.58 NORTH_OUTLET 10.00 43.86 ; DETENTION_POND Storage 0.0 0 DETENTION_POND 0.5 6313 DETENTION_POND 1.5 16604 DETENTION_POND 2.5 31771 DETENTION_POND 3.5 38551 DETENTION_POND 4.5 44128 DETENTION_POND 5.5 50605 [TIMESERIES] ;;Name Date Time Value ;;-------------- ---------- ---------- ---------- EPA SWMM INP FILE FT_COLLINS 1/1/2005 0:05 1.00 FT_COLLINS 1/1/2005 0:10 1.14 FT_COLLINS 1/1/2005 0:15 1.33 FT_COLLINS 1/1/2005 0:20 2.23 FT_COLLINS 1/1/2005 0:25 2.84 FT_COLLINS 1/1/2005 0:30 5.49 FT_COLLINS 1/1/2005 0:35 9.95 FT_COLLINS 1/1/2005 0:40 4.12 FT_COLLINS 1/1/2005 0:45 2.48 FT_COLLINS 1/1/2005 0:50 1.46 FT_COLLINS 1/1/2005 0:55 1.22 FT_C OLLINS 1/1/2005 1:00 1.06 FT_COLLINS 1/1/2005 1:05 1.00 FT_COLLINS 1/1/2005 1:10 0.95 FT_COLLINS 1/1/2005 1:15 0.91 FT_COLLINS 1/1/2005 1:20 0.87 FT_COLLINS 1/1/2005 1:25 0.84 FT_COLLINS 1/1/2005 1:30 0.81 FT_COLLINS 1/1/2005 1:35 0.78 FT_COLLINS 1/1/2005 1:40 0.75 FT_COLLINS 1/1/2005 1:45 0.73 FT_COLLINS 1/1/2005 1:50 0.71 FT_COLLINS 1/1/2005 1:55 0.69 FT_COLLINS 1/1/2005 2:00 0.67 [REPORT] ;;Reporting Options INPUT NO CONTROLS NO SUBCATCHMENTS ALL NODES ALL LINKS ALL [TAGS] EPA SWMM INP FILE [MAP] DIMENSIONS -312.375 6707.339 -113.128 7053.631 Units None [COORDINATES] ;;Node X-Coord Y-Coord ;;-------------- ------------------ ------------------ SOUTH_OUTFALL -303.318 6727.694 NORTH_OUTFALL -124.587 6723.080 DETENTION_POND -206.082 6914.637 [VERTICES] ;;Link X-Coord Y-Coord ;;-------------- ------------------ ------------------ [Polygons] ;;Subcatchment X-Coord Y-Coord ;;-------------- ------------------ ------------------ BASIN_59 -146.483 6994.128 BASIN_59 -146.483 6994.128 BASIN_59 -131.890 6993.005 BASIN_59 -132.264 7011.340 BASIN_59 -147.979 7011.714 BASIN_60 -277.424 6996.362 BASIN_60 -260.586 6996.736 BASIN_60 -260.586 7015.071 BASIN_60 -276.675 7015.071 [SYMBOLS] ;;Gage X-Coord Y-Coord ;;-------------- ------------------ ------------------ RAIN_GAGE -202.632 7024.795 EPA SWMM RESULTS EPA STORM WATER MANAGEMENT MODEL - VERSION 5.1 (Build 5.1.010) -------------------------------------------------------------- TIMBERLINE HOUSING DETENTION POND ANALYSIS ********************************************************* NOTE: The summary statistics displayed in this report are based on results found at every computational time step, not just on results from each reporting time step. ********************************************************* **************** Analysis Options **************** Flow Units ............... CFS Process Models: Rainfall/Runoff ........ YES RDII ................... NO Snowmelt ............... NO Groundwater ............ NO Flow Routing ........... YES Ponding Allowed ........ NO Water Quality .......... NO Infiltration Method ...... HORTON Flow Routing Method ...... KINWAVE Starting Date ............ JAN-01-2005 00:00:00 Ending Date .............. JAN-04-2005 00:00:00 Antecedent Dry Days ...... 0.0 Report Time Step ......... 00:05:00 Wet Time Step ............ 00:05:00 Dry Time Step ............ 00:05:00 Routing Time Step ........ 30.00 sec ************************** Volume Depth Runoff Quantity Continuity acre-feet inches ************************** --------- ------- EPA SWMM RESULTS Total Precipitation ...... 10.029 3.669 Evaporation Loss ......... 0.000 0.000 Infiltration Loss ........ 1.285 0.470 Surface Runoff ........... 8.541 3.125 Final Storage ............ 0.222 0.081 Continuity Error (%) ..... -0.187 ************************** Volume Volume Flow Routing Continuity acre-feet 10^6 gal ************************** --------- --------- Dry Weather Inflow ....... 0.000 0.000 Wet Weather Inflow ....... 8.541 2.783 Groundwater Inflow ....... 0.000 0.000 RDII Inflow .............. 0.000 0.000 External Inflow .......... 0.000 0.000 External Outflow ......... 8.512 2.774 Flooding Loss ............ 0.000 0.000 Evaporation Loss ......... 0.000 0.000 Exfiltration Loss ........ 0.000 0.000 Initial Stored Volume .... 0.000 0.000 Final Stored Volume ...... 0.011 0.004 Continuity Error (%) ..... 0.201 ******************************** Highest Flow Instability Indexes ******************************** All links are stable. ************************* Routing Time Step Summary ************************* Minimum Time Step : 30.00 sec Average Time Step : 30.00 sec Maximum Time Step : 30.00 sec Percent in Steady State : 0.00 Average Iterations per Step : 1.00 EPA SWMM RESULTS Percent Not Converging : 0.00 *************************** Subcatchment Runoff Summary *************************** -------------------------------------------------------------------------------------------------------- Total Total Total Total Total Total Peak Runoff Precip Runon Evap Infil Runoff Runoff Runoff Coeff Subcatchment in in in in in 10^6 gal CFS -------------------------------------------------------------------------------------------------------- BASIN_59 3.67 0.00 0.00 0.49 3.11 1.75 48.02 0.846 BASIN_60 3.67 0.00 0.00 0.44 3.16 1.04 37.60 0.861 ****************** Node Depth Summary ****************** --------------------------------------------------------------------------------- Average Maximum Maximum Time of Max Reported Depth Depth HGL Occurrence Max Depth Node Type Feet Feet Feet days hr:min Feet --------------------------------------------------------------------------------- SOUTH_OUTFALL OUTFALL 0.00 0.00 4921.31 0 00:00 0.00 NORTH_OUTFALL OUTFALL 0.00 0.00 4916.91 0 00:00 0.00 DETENTION_POND STORAGE 1.96 3.88 4925.38 0 01:04 3.87 ******************* Node Inflow Summary ******************* ------------------------------------------------------------------------------------------------- Maximum Maximum Lateral Total Flow Lateral Total Time of Max Inflow Inflow Balance Inflow Inflow Occurrence Volume Volume Error Node Type CFS CFS days hr:min 10^6 gal 10^6 gal Percent EPA SWMM RESULTS ------------------------------------------------------------------------------------------------- SOUTH_OUTFALL OUTFALL 0.00 41.28 0 01:04 0 2.08 0.000 NORTH_OUTFALL OUTFALL 0.00 20.85 0 01:04 0 0.692 0.000 DETENTION_POND STORAGE 85.61 85.61 0 00:45 2.78 2.78 0.202 ********************** Node Surcharge Summary ********************** Surcharging occurs when water rises above the top of the highest conduit. --------------------------------------------------------------------- Max. Height Min. Depth Hours Above Crown Below Rim Node Type Surcharged Feet Feet --------------------------------------------------------------------- DETENTION_POND STORAGE 72.00 3.875 3.125 ********************* Node Flooding Summary ********************* No nodes were flooded. ********************** Storage Volume Summary ********************** -------------------------------------------------------------------------------------------------- Average Avg Evap Exfil Maximum Max Time of Max Maximum Volume Pcnt Pcnt Pcnt Volume Pcnt Occurrence Outflow Storage Unit 1000 ft3 Full Loss Loss 1000 ft3 Full days hr:min CFS -------------------------------------------------------------------------------------------------- DETENTION_POND 29.948 12 0 0 87.248 36 0 01:03 62.12 *********************** EPA SWMM RESULTS Outfall Loading Summary *********************** ----------------------------------------------------------- Flow Avg Max Total Freq Flow Flow Volume Outfall Node Pcnt CFS CFS 10^6 gal ----------------------------------------------------------- SOUTH_OUTFALL 99.81 1.08 41.28 2.081 NORTH_OUTFALL 7.65 4.67 20.85 0.692 ----------------------------------------------------------- System 53.73 5.74 62.12 2.774 ******************** Link Flow Summary ******************** ----------------------------------------------------------------------------- Maximum Time of Max Maximum Max/ Max/ |Flow| Occurrence |Veloc| Full Full Link Type CFS days hr:min ft/sec Flow Depth ----------------------------------------------------------------------------- SOUTH_OUTLET_PIPE DUMMY 41.28 0 01:04 NORTH_OUTLET_PIPE DUMMY 20.85 0 01:04 ************************* Conduit Surcharge Summary ************************* No conduits were surcharged. Analysis begun on: Tue Aug 03 11:16:33 2021 Analysis ended on: Tue Aug 03 11:16:33 2021 Total elapsed time: < 1 sec Project Timberline Housing Project #20.0336 Date 5/30/2021 Title Overall Water Quality Treatment BASIN BASIN AREA (ACRES)% IMP.Basin Q2 Basin Q100 A * I IMP. AREA (ACRES)% IMP. AREA OF TOTAL TREATMENT FACILITY P1 0.164 90%0.36 1.45 0.147 0.147 3%EDB P2 1.105 58%1.32 7.40 0.642 0.499 12%SWALE A P3 0.934 76%1.92 8.07 0.708 0.768 18%RAIN GARDEN A P4 0.278 54%0.23 1.25 0.150 0.054 1%EDB P5 0.196 69%0.32 1.48 0.136 0.110 3%EDB P6 0.457 81%0.93 3.86 0.369 0.367 9%UG FILTRATION B P7 0.842 83%1.69 7.02 0.703 0.670 16%UG FILTRATION B P8 1.605 3%0.29 7.61 0.053 0.022 1%EDB P9 0.356 71%0.50 2.42 0.252 0.175 4%EDB P10 0.811 76%1.58 6.70 0.618 0.636 15%UG FILTRATION A P11 1.098 50%1.51 7.84 0.545 0.584 14%RAIN GARDEN B P12 0.448 71%0.77 3.36 0.318 0.290 7%EDB P13 1 0.331 99%0.81 3.08 0.328 EXCLUDED P14 1 0.435 99%1.06 4.05 0.432 EXCLUDED Total 9.060 65.58 4.281 TREATMENT FACILITY BASIN AREA (ACRES)% IMP.Basin Q2 Basin Q100 IMP. AREA (ACRES) % IMP. AREA OF TOTAL WQCV (CF)COMMENTS EDB 3.047 35%2.47 17.57 0.798 18%35853 NOTE 1 RAIN GARDEN A 0.934 76%1.92 8.07 0.768 18%891 RAIN GARDEN B 1.098 50%1.51 7.84 0.584 14%663 UG FILTRATION A 0.811 76%1.58 6.70 0.636 15%452 UG FILTRATION B 1.299 83%2.61 10.88 1.037 24%848 SWALE A 1.105 58%1.32 7.40 0.499 12%NOTE 3 8.294 11.41 58.45 4.322 0.889 WATER QUALITY DISTRIBUTION 1) Per 2007 Report, the design volum for the existing EDB was 0.991 Acre-Feet. This is reduced by additional water quality features 2) Basins P13 and P14 are included within the draiange study area for the project but are excluded from the total impervious as improvements within these basins are not considered modified impervious area. The basins are currently treated in the existing EDB 3) Grass Swale only provides LID/Filtration. WQCV still contained within EDB This unofficial copy was downloaded on Feb-17-2021 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA Project Timberline Housing Project #20.0336 Date 5/30/2021 Title EDB Water Quality Volume-Existing References Urban Drainage and Flood Control District, Drainage Criteria Manual, 2016 Equations General i 75.47%Basin imperviousness A 32.82 acres Basin Area Drain Time 40 hours FS 1.2 Factor of safety (typically 1) a 1.0 WQCV 0.302 ws-in Water quality capture volume VWQ 0.991 acre-feet Water quality volume within the Denver Region VWQ 43181 ft3 Water quality volume within the Denver Region Notes None WATER QUALITY CAPTURE VOLUME-EXISTING 𝑉𝑄𝐶𝑉=𝑎0.91𝐼3 −1.19𝐼2 +0.78𝐼 𝑉=𝐹𝑆𝑉𝑄𝐶𝑉 12 𝐴 Page 1 of 3 H:\LOVATO\20.0336-Timberline Housing\ENG\DRAINAGE\Calculations\Treatment Facilities\Water Quality Design, Existing EDB.xlsx/Water Quality Design, Existing EDB.xlsx Project Timberline Housing Project #20.0336 Date 5/30/2021 Title Proposed WQ Routing Basin Basin Area (AC)Composite % I I * A Treatment Facility P1 0.16 89.6 14.70 EDB P2 1.11 49.6 54.85 LID P3 1.01 80.3 81.46 LID P4 0.20 53.7 10.64 EDB P5 0.20 69.0 13.52 EDB P6 0.46 81.9 37.43 LID P7 0.84 82.8 69.74 LID P8 1.60 1.4 2.2 EDB P9 0.36 64.6 22.99 EDB P10 0.81 79.5 64.57 LID P11 1.11 53.8 59.58 LID P12 0.44 75.4 33.01 EDB P13 0.33 99.1 32.8 EDB P14 0.44 99.3 43.2 EDB D1 7.40 55.6 411.25 EDB A1 6.39 81.8 522.7 EDB A4 0.08 90.0 6.93 EDB B1 1.69 91.7 155.3 EDB B2 0.90 90.7 81.9 EDB B5 0.04 100.0 4 EDB C1 3.31 91.5 302.8 EDB C3 1.82 90.3 164.11 EDB C4 2.10 90.8 190.82 EDB TOTAL 32.78 72.62 2380.5 TREATMENT FACILITY BASIN AREA (ACRES)% IMP. EDB 25.342 0.79 WATER QUALITY CAPTURE VOLUME Project Timberline Housing Project #20.0336 Date 5/30/2021 Title EDB Water Quality Volume-Proposed References Urban Drainage and Flood Control District, Drainage Criteria Manual, 2016 Equations General i 79.43%Basin imperviousness A 25.34 acres Basin Area Drain Time 40 hours FS 1.2 Factor of safety (typically 1) a 1.0 WQCV 0.325 ws-in Water quality capture volume VWQ 0.823 acre-feet Water quality volume within the Denver Region VWQ 35853 ft3 Water quality volume within the Denver Region Notes FS Factor of 1.2 from 2008 Manual WATER QUALITY CAPTURE VOLUME-PROPOSED 𝑉𝑄𝐶𝑉=𝑎0.91𝐼3 −1.19𝐼2 +0.78𝐼 𝑉=𝐹𝑆𝑉𝑄𝐶𝑉 12 𝐴 Page 3 of 3 H:\LOVATO\20.0336-Timberline Housing\ENG\DRAINAGE\Calculations\Treatment Facilities\Water Quality Design, Existing EDB.xlsx/Water Quality Design, Existing EDB.xlsx Sheet 1 of 1 Designer: Company: Date: Project: Location: 1.Design Discharge for 2-Year Return Period Q2 =1.32 cfs 2.Hydraulic Residence Time A) : Length of Grass Swale LS =200.0 ft B) Calculated Residence Time (based on design velocity below)THR= 4.8 minutes 3.Longitudinal Slope (vertical distance per unit horizontal) A) Available Slope (based on site constraints)Savail =0.005 ft / ft B) Design Slope SD =0.005 ft / ft 4.Swale Geometry A) Channel Side Slopes (Z = 4 min., horiz. distance per unit vertical)Z =4.00 ft / ft B) Bottom Width of Swale (enter 0 for triangular section)W B =4.00 ft 5.Vegetation A) Type of Planting (seed vs. sod, affects vegetal retardance factor) 6.Design Velocity (0.667 ft / s maximum for desirable 5-minute residence time)V2 =0.70 ft / s 7.Design Flow Depth (1 foot maximum)D2 =0.35 ft A) Flow Area A2 =1.9 sq ft B) Top Width of Swale WT =6.8 ft C) Froude Number (0.50 maximum)F = 0.23 D) Hydraulic Radius RH = 0.27 E) Velocity-Hydraulic Radius Product for Vegetal Retardance VR = 0.19 F) Manning's n (based on SCS vegetal retardance curve E for seeded grass)n = 0.064 G) Cumulative Height of Grade Control Structures Required HD =0.00 ft AN UNDERDRAIN IS 8.Underdrain REQUIRED IF THE (Is an underdrain necessary?)DESIGN SLOPE < 2.0% 9.Soil Preparation (Describe soil amendment) 10.Irrigation Notes: Design Procedure Form: Grass Swale (GS) B. Nemec Martin/Martin May 31, 2021 Timberline Housing Ft. Collins UD-BMP (Version 3.07, March 2018) Choose One Temporary Permanent Choose One Grass From Seed Grass From Sod Choose One YES NO Water Quality Design, BioSwale A.xlsm, GS 5/31/2021, 12:33 Project Timberline Housing Project #20.0336 Date 5/30/2021 Title Rain Garden A Design References Urban Drainage and Flood Control District, Drainage Criteria Manual, 2016 Equations General i 80.0%Basin imperviousness A 0.93 acres Basin Area Drain Time 12 hours FS 1 Factor of safety WQCV 0.263 ws-in Water quality capture volume VWQ minimum 0.0204 acre-feet Water quality volume within the Denver Region VWQ minimim 890.7 ft Water quality volume within the Denver Region dWQ 1.054 ft Depth of water quality storage Arain garden minimum 651.05 ft2 Minimum surface area Arain garden 845.00 ft2 Minimum surface area drain garden 1.50 ft Depth of media INVorifice 5500.17 ft Invert out of rain garden underdrain orifice ELEVmedia surface 5501.75 ft Elevation of the Rain Garden surface ELEVmedia base 5500.25 ft Elevation of the top of Underdrain Section WSELwater quality 5502.80 ft Elevation of the water surface y 1.58 ft Distance between bottom of storage volume to orifice centroid Dorifice 0.72 in Outlet orifice diameter (minimum 3/8") RAIN GARDEN DESIGN 𝑉𝑃𝐶𝑉=𝑎0.91𝐻3 −1.19𝐻2 +0.78𝐻𝑤ℎ𝑒𝑟𝑒𝑎=0.8 𝑉=𝐹𝑆𝑉𝑃𝐶𝑉 12 𝐴 𝐴𝑟𝑎𝑖𝑛𝑐𝑎𝑟𝑐𝑐𝑛=0.02 ∙𝐴∙𝐻 𝐶𝑛𝑟𝑖𝑐𝑖𝑐𝑐=𝑉 1414 ∙𝑦0.41 Page 1 of 4 H:\LOVATO\20.0336-Timberline Housing\ENG\DRAINAGE\Calculations\Treatment Facilities\Rain Gardens A and B.xlsx/Rain Gardens A and B.xlsx Project Timberline Housing Project #20.0336 Date 5/30/2021 Title Rain Garden A Design-Bypass Inlet References none Formulas GENERAL- 100yr Inlet Type N 1 #Number of Inlets Qreq 8.07 cfs Required flow for inlet- 100yr X 0.50 %Clogging Factor WEIR P 12 ft Inlet perimeter Hweir 0.55 ft Water depth for weir flow ORIFICE A 907 in2 Free open area of orifice (ft²) Co 0.64 Discharge coefficient for orifice (0.60-0.65) Horifice 0.25 ft Water depth for orifice flow Flow Type Weir flow type Depth 0.55 ft Flow depth at inlet WSEL 5502.82 ft Elev of 100yr Notes none INLET DESIGN, ORIFICE-WEIR, KNOWN FLOW CDOT Type C 𝐻𝑛𝑟𝑖𝑐𝑖𝑐𝑐=1 2𝑔 𝑃𝑛𝑟𝑖𝑐𝑖𝑐𝑐 𝐶𝑛𝐴 2 𝐻𝑤𝑐𝑖𝑟=3𝑃𝑤𝑐𝑖𝑟 2𝐶𝑤𝑃2𝑔0.5 ൗ23 𝑤ℎ𝑒𝑟𝑒𝐶𝑤=0.62 Page 2 of 4 H:\LOVATO\20.0336-Timberline Housing\ENG\DRAINAGE\Calculations\Treatment Facilities\Rain Gardens A and B.xlsx/Rain Gardens A and B.xlsx Project Timberline Housing Project #20.0336 Date 5/30/2021 Title Rain Garden B Design References Urban Drainage and Flood Control District, Drainage Criteria Manual, 2016 Equations General i 50.6%Basin imperviousness A 1.10 acres Basin Area Drain Time 12 hours FS 1 Factor of safety WQCV 0.166 ws-in Water quality capture volume VWQ minimum 0.0152 acre-feet Water quality volume within the Denver Region VWQ minimim 663.1 ft Water quality volume within the Denver Region dWQ 0.56 ft Depth of water quality storage Arain garden minimum 484.21 ft2 Minimum surface area Arain garden 1174.00 ft2 Minimum surface area drain garden 1.50 ft Depth of media INVorifice 5500.17 ft Invert out of rain garden underdrain orifice ELEVmedia surface 5501.75 ft Elevation of the Rain Garden surface ELEVmedia base 5500.25 ft Elevation of the top of Underdrain Section WSELwater quality 5502.31 ft Elevation of the water surface y 1.58 ft Distance between bottom of storage volume to orifice centroid Dorifice 0.62 in Outlet orifice diameter (minimum 3/8") RAIN GARDEN DESIGN 𝑉𝑃𝐶𝑉=𝑎0.91𝐻3 −1.19𝐻2 +0.78𝐻𝑤ℎ𝑒𝑟𝑒𝑎=0.8 𝑉=𝐹𝑆𝑉𝑃𝐶𝑉 12 𝐴 𝐴𝑟𝑎𝑖𝑛𝑐𝑎𝑟𝑐𝑐𝑛=0.02 ∙𝐴∙𝐻 𝐶𝑛𝑟𝑖𝑐𝑖𝑐𝑐=𝑉 1414 ∙𝑦0.41 Page 3 of 4 H:\LOVATO\20.0336-Timberline Housing\ENG\DRAINAGE\Calculations\Treatment Facilities\Rain Gardens A and B.xlsx/Rain Gardens A and B.xlsx Project Timberline Housing Project #20.0336 Date 5/30/2021 Title Rain Garden B Design-Bypass Inlet References none Formulas GENERAL- 100yr Inlet Type N 1 #Number of Inlets Qreq 7.84 cfs Required flow for inlet- 100yr X 0.50 %Clogging Factor WEIR P 12 ft Inlet perimeter Hweir 0.54 ft Water depth for weir flow ORIFICE A 907 in2 Free open area of orifice (ft²) Co 0.64 Discharge coefficient for orifice (0.60-0.65) Horifice 0.23 ft Water depth for orifice flow Flow Type Weir flow type Depth 0.54 ft Flow depth at inlet WSEL 5502.81 ft Elev of 100yr Notes none INLET DESIGN, ORIFICE-WEIR, KNOWN FLOW CDOT Type C 𝐻𝑛𝑟𝑖𝑐𝑖𝑐𝑐=1 2𝑔 𝑃𝑛𝑟𝑖𝑐𝑖𝑐𝑐 𝐶𝑛𝐴 2 𝐻𝑤𝑐𝑖𝑟=3𝑃𝑤𝑐𝑖𝑟 2𝐶𝑤𝑃2𝑔0.5 ൗ23 𝑤ℎ𝑒𝑟𝑒𝐶𝑤=0.62 Page 4 of 4 H:\LOVATO\20.0336-Timberline Housing\ENG\DRAINAGE\Calculations\Treatment Facilities\Rain Gardens A and B.xlsx/Rain Gardens A and B.xlsx Project Timberline Housing Project #20.0336 Date 8/17/2021 Title Underground Filtration A References Urban Drainage and Flood Control District, Drainage Criteria Manual, 2016 Equations General i 76.2%Basin imperviousness A 0.720 acres Basin Area Drain Time 12 hours FS 1 Factor of safety (typically 1) a 0.8 WQCV 0.245 ws-in Water quality capture volume VWQ 0.015 acre-feet Water quality volume within the Denver Region VWQ 640 ft3 Water quality volume within the Denver Region #chambers 49 Quantity of Chambers Achamber 18.33 ft2 Minimum surface area Afilter 898.17 ft2 Design surface area dfilter 1.00 ft Depth of media ELEVsurface ft Elevation of the filter surface ELEVchamber ft Elevation of the top of the chamber ELEVfilter base ft Elevation of the bottom of the filter media INVorifice ft Invert out of filter system Notes Basin P10 UNDERGROUND FILTRATION 𝑉𝑄𝐶𝑉=𝑎0.91𝐼3 −1.19𝐼2 +0.78𝐼 𝑉=𝐹𝑆𝑉𝑄𝐶𝑉 12 𝐴 Page 1 of 3 H:\LOVATO\20.0336-Timberline Housing\ENG\DRAINAGE\Calculations\Treatment Facilities\Water Quality Design, Underground Filtration Volume.xlsx/Water Quality Design, Underground Filtration Volume.xlsx Project Timberline Housing Project #20.0336 Date 8/17/2021 Title Underground Filtration B References Urban Drainage and Flood Control District, Drainage Criteria Manual, 2016 Equations General i 80.8%Basin imperviousness A 0.460 acres Basin Area Drain Time 12 hours FS 1 Factor of safety (typically 1) a 0.8 WQCV 0.267 ws-in Water quality capture volume VWQ 0.010 acre-feet Water quality volume within the Denver Region VWQ 445 ft3 Water quality volume within the Denver Region #chambers 72 Quantity of Chambers Achamber 17.23 ft2 Minimum surface area Afilter 1240.56 ft2 Design surface area dfilter 1.00 ft Depth of media ELEVsurface ft Elevation of the filter surface ELEVchamber ft Elevation of the top of the chamber ELEVfilter base ft Elevation of the bottom of the filter media INVorifice ft Invert out of filter system Notes Basin P6 Basin P6 and Basin P7 combined into one underground filtration system UNDERGROUND FILTRATION 𝑉𝑄𝐶𝑉=𝑎0.91𝐼3 −1.19𝐼2 +0.78𝐼 𝑉=𝐹𝑆𝑉𝑄𝐶𝑉 12 𝐴 Page 2 of 3 H:\LOVATO\20.0336-Timberline Housing\ENG\DRAINAGE\Calculations\Treatment Facilities\Water Quality Design, Underground Filtration Volume.xlsx/Water Quality Design, Underground Filtration Volume.xlsx Project Timberline Housing Project #20.0336 Date 8/17/2021 Title Underground Filtration B References Urban Drainage and Flood Control District, Drainage Criteria Manual, 2016 Equations General i 83.5%Basin imperviousness A 0.830 acres Basin Area Drain Time 12 hours FS 1 Factor of safety (typically 1) a 0.8 WQCV 0.281 ws-in Water quality capture volume VWQ 0.019 acre-feet Water quality volume within the Denver Region VWQ 847 ft3 Water quality volume within the Denver Region #chambers 72 Quantity of Chambers Achamber 17.23 ft2 Minimum surface area Afilter 1240.56 ft2 Design surface area dfilter 1.00 ft Depth of media ELEVsurface ft Elevation of the filter surface ELEVchamber ft Elevation of the top of the chamber ELEVfilter base ft Elevation of the bottom of the filter media INVorifice ft Invert out of filter system Notes For Basin P7 Basin P6 and Basin P7 combined into one underground filtration system UNDERGROUND FILTRATION 𝑉𝑄𝐶𝑉=𝑎0.91𝐼3 −1.19𝐼2 +0.78𝐼 𝑉=𝐹𝑆𝑉𝑄𝐶𝑉 12 𝐴 Page 3 of 3 H:\LOVATO\20.0336-Timberline Housing\ENG\DRAINAGE\Calculations\Treatment Facilities\Water Quality Design, Underground Filtration Volume.xlsx/Water Quality Design, Underground Filtration Volume.xlsx Stormwater Facility Name: Facility Location & Jurisdiction: User Input: Watershed Characteristics User Defined User Defined User Defined User Defined Selected BMP Type =EDB Stage [ft]Area [ft^2]Stage [ft]Discharge [cfs] Watershed Area =37.21 acres 0.00 0 0.00 0.00 Watershed Length =1,500 ft 0.50 4,514 1.00 0.25 Watershed Length to Centroid =750 ft 1.50 19,706 2.00 0.35 Watershed Slope =0.006 ft/ft 2.50 32,052 3.00 0.45 Watershed Imperviousness =74.5%percent 3.50 40,809 4.00 63.69 Percentage Hydrologic Soil Group A =0.0%percent 4.50 49,510 5.00 81.19 Percentage Hydrologic Soil Group B =0.0%percent 5.50 68,295 5.50 89.13 Percentage Hydrologic Soil Groups C/D =100.0%percent Target WQCV Drain Time =40.0 hours Denver - Capitol Building After completing and printing this worksheet to a pdf, go to: https://maperture.digitaldataservices.com/gvh/?viewer=cswdif Create a new stormwater facility, and attach the PDF of this worksheet to that record. Routed Hydrograph Results Design Storm Return Period =WQCV 2 Year 5 Year 10 Year 50 Year 100 Year One-Hour Rainfall Depth =N/A 0.83 1.09 1.33 1.99 2.31 in CUHP Runoff Volume =0.921 1.795 2.537 3.273 5.488 6.597 acre-ft Inflow Hydrograph Volume =N/A 1.795 2.537 3.273 5.488 6.597 acre-ft Time to Drain 97% of Inflow Volume =35.1 46.3 44.8 43.7 40.5 39.0 hours Time to Drain 99% of Inflow Volume =37.3 49.3 48.6 47.9 46.3 45.6 hours Maximum Ponding Depth =2.53 3.09 3.24 3.37 3.92 4.24 ft Maximum Ponded Area =0.74 0.85 0.88 0.91 1.02 1.08 acres Maximum Volume Stored =0.922 1.360 1.494 1.612 2.142 2.473 acre-ft Once CUHP has been run and the Stage-Area-Discharge information has been provided, click 'Process Data' to interpolate the Stage-Area-Volume-Discharge data and generate summary results in the table below. Once this is complete, click 'Print to PDF'. Stormwater Detention and Infiltration Design Data Sheet SDI-Design Data v2.00, Released January 2020 Location for 1-hr Rainfall Depths (use dropdown): After providing required inputs above including 1-hour rainfall depths, click 'Run CUHP' to generate runoff hydrographs using the embedded Colorado Urban Hydrograph Procedure. SDI_Design_Compliance.xlsm, Design Data 6/1/2021, 16:56 Booleans for Message Booleans for CUHP Watershed L:W 1 CUHP Inputs Complete Watershed Lc:L 1 CUHP Results Calculated Watershed Slope FALSE Time Interval RunOnce 1 CountA 1 Draintime Coeff 1.0 User Precip 1 Equal SA Inputs 1 Equal SD Inputs 1 Stormwater Detention and Infiltration Design Data Sheet 0 20 40 60 80 100 120 0.1 1 10FLOW [cfs]TIME [hr] 100YR IN 100YR OUT 50YR IN 50YR OUT 10YR IN 10YR OUT 5YR IN 5YR OUT 2YR IN 2YR OUT WQCV IN WQCV OUT 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 0.1 1 10 100PONDING DEPTH [ft]DRAIN TIME [hr] 100YR 50YR 10YR 5YR 2YR WQCV SDI_Design_Compliance.xlsm, Design Data 6/1/2021, 16:56 TIMBERLINE ATTAINABLE HOUSING June 2, 2021 APPENDI X D - SUPPORTING DOCUMENTS REPORT COVER PAGE Geotechnical Engineering Report __________________________________________________________________________ Timberline Apartments Fort Collins, Colorado May 5, 2021 Terracon Project No. 20215032 Prepared for: Tetrad Property Group, LLC Fort Collins, Colorado Prepared by: Terracon Consultants, Inc. Fort Collins, Colorado Responsive ■ Resourceful ■ Reliable 1 REPORT TOPICS INTRODUCTION ............................................................................................................. 1 SITE CONDITIONS ......................................................................................................... 1 PROJECT DESCRIPTION .............................................................................................. 2 GEOTECHNICAL CHARACT ERIZATION ...................................................................... 3 GEOTECHNICAL OVERVIEW ....................................................................................... 5 EARTHWORK................................................................................................................. 7 SHALLOW FOUNDATIONS ......................................................................................... 12 SEISMIC CONSIDERATIONS ...................................................................................... 17 FLOOR SLABS............................................................................................................. 17 BELOW-GRADE STRUCTURES ................................................................................. 19 PAVEMENTS ................................................................................................................ 22 FROST CONSIDERATIONS ......................................................................................... 25 CORROSIVITY.............................................................................................................. 26 GENERAL COMMENTS ............................................................................................... 26 Note: This report was originally delivered in a web-based format. Orange Bold text in the report indicates a referenced section heading. The PDF version also includes hyperlinks which direct the reader to that section and clicking on the GeoReport logo will bring you back to this page. For more interactive features, please view your project online at client.terracon.com. ATTACHMENTS EXPLORATION AND TESTING PROCEDURES SITE LOCATION AND EXPLORATION PLANS EXPLORATION RESULTS SUPPORTING INFORMATION Note: Refer to each individual Attachment for a listing of contents. Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable i REPORT SUMMARY Topic 1 Overview Statement 2 Project Overview A geotechnical exploration has been performed for the proposed Timberline Apartments to be constructed at 2908 South Timberline Road in Fort Collins, Colorado. Seven (7) borings were performed to depths of approximately 25 to 30 feet below existing site grades. Detailed recommendations for the design of storm water retention features and the pond are outside our scope of work. Subsurface Conditions Subsurface conditions encountered in our exploratory borings generally consisted of about 9 to 13 feet of silt or clay with varying amounts of sand and gravel over about 4 to 12 feet of sand and gravel. Claystone bedrock was encountered below the overburden soils at depths of approximately 17 to 21 feet below existing site grades. The upper approximately 6 inches to 2 feet of bedrock was weathered and comparatively soft in some of the borings. Boring logs are presented in the Exploration Results section of this report. Groundwater Conditions Groundwater was encountered in all of our test borings at depths of about 12 to 13 feet below existing site grades at the time of drilling. Groundwater levels can fluctuate in response to site development and to varying seasonal and weather conditions, irrigation on or adjacent to the site and fluctuations in nearby water features. Geotechnical Concerns ■ As previously stated, groundwater was measured at depths ranging from about 12 to 13 feet below existing site grades. Groundwater level fluctuations occur due to seasonal variations in the water levels present in nearby water features, amount of rainfall, runoff and other factors not evident at the time the borings were performed. Therefore, groundwater levels during construction or at other times in the life of the structure(s) may be higher or lower than the levels indicated on the boring logs. Terracon recommends maintaining a separation of at least 3 feet between the bottom of proposed below-grade foundations and measured groundwater levels. Final site grading should be planned and designed to avoid cuts where shallow groundwater is known to exist, and also in areas where such grading would create shallow groundwater conditions. If deeper cuts are unavoidable, temporary construction dewatering and/or installation of a subsurface drainage system may be needed. ■ Com paratively soft lean clay and silt soils were encountered within the upper approximately 9 to 13 feet in some of the borings completed at this site. These materials present a risk for potential settlement of shallow foundations, floor slabs, pavements and other surficial improvements. These materials can also be susceptible to disturbance and loss of strength under repeated construction traffic loads and unstable conditions could develop. Stabilization of soft soils may be required at some locations to provide adequate support for construction equipment and proposed structures. Terracon should be contacted if these conditions are encountered to observe the conditions exposed and to provide guidance regarding stabilization (if needed). Earthwork On-site soils typically appear suitable for use as general engineered fill and backfill on the site provided they are placed and compacted as described in this report. Import materials (if needed) should be evaluated and approved by Terracon prior to delivery to the site. Earthwork recommendations are presented in the Earthwork section of this report. Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable ii Topic 1 Overview Statement 2 Grading and Drainage The amount of movement of foundations, floor slabs, pavements, etc. will be related to the wetting of underlying supporting soils. Therefore, it is imperative the recommendations discussed in the Grading and Drainage section of the Earthwork section this report be followed to reduce potential movement. As discussed in the Grading and Drainage section of this report, surface drainage should be designed, constructed and maintained to provide rapid removal of surface water runoff away from the proposed buildings and pavements. Water should not be allowed to pond adjacent to foundations or on pavements and conservative irrigation practices should be followed to avoid wetting foundation/slab soils and pavement subgrade. Excessive wetting of foundations/slab soils and subgrade can cause movement and distress to foundations, floor slabs, concrete flatwork and pavements. Foundations We understand the project team is planning to support the proposed buildings on post-tensioned slab foundations. Based on the subsurface conditions encountered, use of post-tensioned slabs is feasible for support of the structures provided some foundation movement can be tolerated. As an alternative to post-tensioned slabs, or for other structures planned on the site, shallow spread footing foundations can be used. Design recommendations for foundations for the proposed structure and related structural elements are presented in the Shallow Foundations section of this report. Floor Systems For structures supported on a post-tensioned slab foundation system, the foundation will also function as the floor system. If a conventional spread footing is used as a foundation system, a slab-on-grade floor system is recommended provided the soils are over-excavated to a depth of at least 2 feet below the proposed floor slab and replaced with moisture conditioned, properly compacted engineered fill. On-site soils are suitable as over-excavation backfill below floor slabs. Design recommendations for floor systems for the proposed structure and related structural elements are presented in the Floor Slabs section of this report. Pavements Recommended Pavement thicknesses for this project include 3½ inches of asphalt over 6 inches of aggregate base course in light-duty parking areas and 6 inches of asphalt over 6 inches of aggregate base course in heavy-duty drive lanes and loading areas. Additional pavement section alternatives and discussion are presented in the report. Seismic Considerations As presented in the Seismic Considerations section of this report, the International Building Code, which refers to Section 20 of ASCE 7, indicates the seismic site classification for this site is D. Construction Observation and Testing Close monitoring of the construction operations and implementing drainage recommendations discussed herein will be critical in achieving the intended foundation, slab and pavement performance. We therefore recommend that Terracon be retained to monitor this portion of the work. General Comments This section contains important information about the limitations of this geotechnical engineering report. 1. If the reader is reviewing this report as a pdf, the topics (bold orange font) above can be used to access the appropriate section of the report by simply clicking on the topic itself. 2. This summary is for convenience only. It should be used in conjunction with the entire report for design making and design purposes. It should be recognized that specific details were not included or fully developed in this section, and the report must be read in its entirety for a comprehensive understanding of the items contained herein. Responsive ■ Resourceful ■ Reliable 1 INTRODUC TION Geotechnical Engineering Report Timberline Apartments 2908 South Timberline Road Fort Collins, Colorado Terracon Project No. 20215032 May 5, 2021 INTRODUCTION This report presents the results of our subsu rface exploration and geotechnical engineering services performed for the proposed Timberline Apartments to be located at 2908 South Timberline Road in Fort Collins, Colorado. The purpose of these services is to provide information and geotechnical engineering recommendations relative to: ■ Subsurface soil and rock conditions ■ Foundation design and construction ■ Groundwater conditions ■ Floor system design and construction ■ Site preparation and earthwork ■ Seismic considerations ■ Demolition considerations ■ Lateral earth pressures ■ Excavation considerations ■ Pavement design and construction ■ Dewatering considerations The geotechnical engineering scope of services for this project include d the advancement of seven (7) test borings to depths ranging from approximately 25 to 30 feet below existing site grades. Maps showing the site and boring locations are shown in the Site Location and Exploration Plan sections, respectively. The results of the laboratory testing performed on soil and bedrock samples obtained from the site during the field exploration are included on the boring logs and as separate graphs in the Exploration Results section of this report. SITE CONDITIONS The following description of site conditions is derived from our site visit in association with the field exploration and our review of publicly available geologic and topographic maps. Item Description Parcel Information The project site is located on the south and east sides of 2908 South Timberline Road in Fort Collins, Colorado. The approximate Latitude/Longitude of the center of the site is 40.54676° N/105.03551°W (Please refer to Site Location). Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 2 Item Description Existing Improvements The site is currently occupied by parking areas associated with the existing Timberline Church, located northwest of the site and native grasses and weeds around the existing parking area. Surrounding Developments The site is generally surrounded by residential developments and some commercial developments. To the northwest of the site is the existing Timberline Church and associated parking areas and landscaped areas. An existing canal is present to the south of the site. Current Ground Cover The current ground cover in the areas of exploration were primarily native grasses and weeds and some areas of asphalt surfacing. Existing Topography Based on observations during our site visit and the provided site-surveyed topographic maps, the site is relatively flat and total elevation change across the site is about 5 to 10 feet. PROJECT DESCRIPTION Our final understanding of the project conditions is as follows: Item Description Information Provided The following project information was provided to us through the following: ■ Conversation with the client. ■ Boundary & Topography Survey for Timberline Church and C.S.U. Property, 2908 S Timberline Road, prepared by Olsson and dated March 26, 2021. ■ Conceptual Site Plan for Timberline Apartments, prepared by KBPHart and dated March 14, 2021. Project Description We understand the project includes the construction of 180 apartment units in seven (7) 3-story, walk-up apartment buildings. W e understand the apartment buildings will be supported on post-tensioned slab foundations. In addition, the project will include 288 parking spaces, drive lanes and access roads, landscaped islands, sideways and a detention pond. We anticipate new underground utilities will also be included in the proposed construction. Project Understanding Terracon’s proposed scope of services presented in this proposal has been provided under the belief that this site will be used as apartments. As such, Terracon would like to inform the Client that if this apartment project is converted at any time to another purpose such as condominiums, the Client understands the services Terracon is proposing are not applicable for a condominium project and that a separate consultant will need to be retained for such services. Terracon will have no liability for any such unintended use of our services and Client agrees to defend, indeminify, and hold harmless Terracon for any such unintended usage. Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 3 Item Description Maximum Loads (assumed) ■ Columns: 50 to 200 kips ■ Walls: 1 to 4 kips per linear foot (klf) ■ Slabs: 150 pounds per square foot (psf) Grading/Slopes We anticipate minor cuts and fills on the order of 5 feet or less will be required to achieve proposed grades. Below-grade Structures ■ We understand no below-grade areas (including basements or swimming pools) are planned for this site. ■ We anticipate elevator pits will likely be included in the project ■ We understand a retaining wall may be included in the project. Pavements ■ We assume both rigid (concrete) and flexible (asphalt) pavement sections should be considered. Please confirm this assumption. ■ Traffic loads were not provided at the time of this report. We have assumed traffic loads based on our understanding of the proposed construction and our experience with similar projects ■ Pavements were designed using procedures outlined by the National Asphalt Pavement Associations (NAPA) and the American Concrete Institute (ACI). If project information or assumptions vary from what is described above or if location of construction changes, we sho uld be contacted as soon as possible to confirm and/or modify our recommendations accordingly. GEOTECHNICAL CHARACTERIZATION Subsurface Profile We have developed a general characterization of the subsurface conditions based upon our review of the subsurface exploration, laboratory data, geologic setting and our understanding of the project. This characterization, termed GeoModel, forms the basis of our geotechnical calculations and evaluation of site preparation and foundation options. Conditions encounter ed at each exploration point are indicated on the individual logs. The individual logs and the GeoModel can be found in the Exploration Results section this report. Model Layer Layer Name General Description Approximate Depth to Bottom of Stratum - Surface Asphalt or native grasses and weeds - 1 Silt Sandy silt to sandy elastic silt, brown to dark brown, light brown/orange brown and tan, soft to very stiff About 9½ to 12 feet below existing site grades on the southwest side of the site, near the vicinity of buildings 4, 5, 6 and 7. Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 4 Model Layer Layer Name General Description Approximate Depth to Bottom of Stratum 2 Lean Clay Lean clay with varying amounts of sand and trace amounts of gravel, brown to red brown with light gray, medium stiff to very stiff About 12 to 13 feet below existing site grades on the north side of the site, near vicinity of buildings 1, 2 and 3. 3 Sand and Gravel Poorly graded gravel with sand, brown to red brown, dense to very dense About 17 to 21 feet below existing site grades. 4 Bedrock Claystone bedrock, weathered zone in the upper 6 inches to 2 feet, light brown with orange and gray in weathered zone, gray to dark gray and very hard in competent bedrock To the maximum depths of exploration of about 25 to 30 feet below existing site grades. As noted in General Comments, this characterization is based upon widely spaced exploration points across the site and variations are likely. Groundwater Conditions The boreholes were observed while drilling for the presence and level of groundwater. Upon removal of augers/samplers the boreholes caved due to the sand and gravel soil encountered above bedrock, therefore groundwater levels after drilling were not able to be obtained. The water levels observed in the boreholes are noted on the attached boring logs, and are summarized below: Boring Number Depth to Groundwater While Drilling, ft. Elevation of Groundwater While Drilling, ft. 1 12 4,919 2 12 4,919 3 12 4,916 4 13 4,917 5 13 4,915 6 12 4,917 7 13 4,917 These observations represent short-term groundwater conditions at the time of and shortly after the field exploration and may not be indicative of other times or at other locations. Groundwater levels can be expected to fluctuate with varying seasonal and weather conditions, and other factors. Groundwater level fluctuations occur due to seasonal variations in the water levels present in nearby water features, amount of rainfall, runoff and other factors not evident at the time the borings were performed. Therefore, groundwater levels during construction or at other times in the life of the structure(s) may be higher or lower than the levels indicated on the boring logs. The Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 5 possibility of groundwater level fluctuations should be considered when developing the design and construction plans for the project. Fluctuations in groundwater levels can best be determined by implementation of a groundwater monitoring plan. Such a plan would include installation of groundwater piezometers, and periodic measurement of groundwater levels over a sufficient period of time. Laboratory Testing Representative soil samples were selected for swell-consolidation testing and exhibited no movement to 0.4 percent swell when wetted. Samples of site soils and bedrock exhibited unconfined compressive strengths of approximately 942 and 8,158 pounds per square foot (psf). Samples of site soils and bedrock selected for plasticity testing exhibited low to moderate plasticity with liquid limits ranging from non -plastic to 50 and plasticity indices ranging from non-plastic to 29. Laboratory test results are presented in the Exploration Results section of this report. Soil Infiltration Rate W e understand the project is considering LID design and the impacts of an infiltration systems near structures. Based on the soil encountered in our exploratory borings, we believe the soil encountered in the upper 10 feet on the site will likely be hydrologic soil group C and will likely have a slow infiltration rate when thoroughly wetted. Percolation tests or double -ring infiltrometer tests can be used to determine actual infiltration rat e of the on-site soils. These services were not included in our scope of work for project; however, can be completed, for an additional fee at the request of the client. GEOTECHNICAL OVERVIEW Based on subsurface conditions encountered in the borings, the site appears suitable for the proposed construction from a geotechnical point of view provided certain precautions and design and construction recommendations described in this report are followed. We have identified several geotechnical conditions that could impact design, construction and performance of the proposed structures, pavements, and other site improvements. These included shallow groundwater and potentially soft, low strength clay and silt soils. These conditions will require particular attention in project planning, design and during construction and are discussed in greater detail in the following sections. Shallow Groundwater As previously stated, groundwater was measured at depths ranging from about 12 to 13 feet below existing site grades. Groundwater level fluctuations occur due to seasonal variations in the water levels present in nearby water features, amount of rainfall, runoff and other factors not Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 6 evident at the time the borings were performed. Therefore, groundwater levels during construction or at other times in the life of the structure(s) may be higher or lower than the levels indicated on the boring logs. Terracon recommends maintaining a separation of at least 3 feet between the bottom of proposed below -grade foundations and measured groundwater levels. Final site grading should be planned and designed to avoid cuts where shallow groundwater is known to exist, and also in areas where such grading would create shallow groundwater conditions. If deeper cuts are unavoidable, temporary construction dewatering and/or installation of a subsurface drainage system may be needed. Low Strength Soils Comparatively soft lean clay and silt soils were encountered within the upper approximately 9 to 13 feet in some of the borings completed at this site. These materials present a risk for potential settlement of shallow foundations, floor slabs, pavements and other surficial improvements. These materials can also be susceptible to disturbance and loss of strength under repeated construction traffic loads and unstable conditions could develop. Stabilization of soft soils may be required at some locations to provide adequate support for construction equipment and proposed structures. Terracon should be contacted if these conditions are encountered to observe the conditions exposed and to provide guidance regarding stabilization (if needed). Foundation and Floor System Recommendations We understand the project team is planning to support the proposed buildings on post -tensioned slabs. Based on the subsurface conditions encountered, use of post -tensioned slab foundations is feasible for support of the structures provided some foundation movement can be tolerated. As an alternative to post-tensioned slabs, or for other structures planned on the site, shallow spread footing foundations can be used. Design recommendations for foundations for the proposed structure and related structural elements are presented in the Shallow Foundations section of this report. For structures supported on a post -tensioned slab foundation system, the foundation will also function as the floor system. If a conventional spread footing is used as a foundation system, a slab-on-grade floor system is recommended provided the soils are over-excavated to a depth of at least 2 feet below the proposed floor slab and replaced with moisture conditioned, properly compacted engineered fill. On-site soils are suitable as over-excavation backfill below floor slabs. Design recommendations for floor systems for the proposed structure and related structural elements are presented in the Floor Slabs section of this report. The General Comments section provides an understanding of the report limitations. Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 7 EARTHWORK The following presents recommendations for site preparation , demolition, excavation, subgrade preparation, fill materials, compaction requirements, utility trench backfill, grading and drainage and exterior slab design and construction. Earthwork on the project should be observed and evaluated by Terracon. Evaluation of earthwork should include observation and/or testing of over - excavation, subgrade preparation, placement of engineered fills, subgrade stabilization and other geotechnical conditions exposed during the construction of the project. Site Preparation Prior to placing any fill, strip and remove existing vegetatio n, topsoil, and any other deleterious materials from the proposed construction areas. Stripped organic materials should be wasted from the site or used to re -vegetate landscaped areas or exposed slopes after completion of grading operations. Prior to the placement of fills, the site should be graded to create a relatively level surface to receive fill, and to provide for a relatively uniform thickness of fill beneath proposed structures. Demolition Demolition of the existing parking lots and concrete should include complete removal of all and exterior flat work within the proposed construction area. This should include removal of any utilities to be abandoned along with any loose utility trench backfill or loose backfill found adjacent to existing foundations. All materials derived from the demolition of existing structures and pavements should be removed from the site. Consideration could be given to re-using the asphalt and concrete provided the materials are processed and uniformly blended with the on -site soils. Asphalt and/or concrete materials should be processed to a maximum size of 2 inches and blended at a ratio of 30 percent asphalt/concrete to 70 percent of on-site soils. Excavation It is anticipated that excavations for the proposed construction can be a ccomplished with conventional earthmoving equipment. Excavations into the on-site soils will encounter weak and/or saturated soil conditions with possible caving conditions. The soils to be excavated can vary significantly across the site as their class ifications are based solely on the materials encountered in widely-spaced exploratory test borings. The contractor should verify that similar conditions exist throughout the proposed area of excavation. If different subsurface conditions are encountered at the time of construction, the actual conditions should be evaluated to determine any excavation modifications necessary to maintain safe conditions. Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 8 Although evidence of fills or underground facilities such as grease pits, septic tanks, vaults, basements, and utilities was not observed during the site reconnaissance, such features could be encountered during construction. If unexpected underground facilities are encountered, such features should be removed and the excavation thoroughly cleaned prior to backfill placement and/or construction. Any over-excavation that extends below the bottom of foundation elevation should extend laterally beyond all edges of the foundations at least 8 inches per foot of over -excavation depth below the foundation base elevation. The over-excavation should be backfilled to the foundation base elevation in accordance with the recommendations presented in this report. Depending upon depth of excavation and seasonal conditions, surface water infiltration and/or groundwater may be encountered in excavations on the site. It is anticipated that pumping from sumps may be utilized to control water within excavations. Well points may be required for significant groundwater flow, or where excavations penetrate groundwater to a significant depth. Groundwater seepage should be anticipated for excavations approaching the level of bedrock. The subgrade soil conditions should be evaluated during the excavation process and the stability of the soils determined at that time by the contractors’ Competent Person. Slope inclinations flatter than the OSHA maximum values may have to be used. The individual contractor(s) should be made responsible for designing and constructing stable, temporary excavations as required to maintain stability of both the excavation sides and bottom. All excavations should be sloped or shored in the interest of safety following local, and federal regulations, including current OSHA excavation and trench safety standards. As a safety measure, it is recommended that all vehicles and soil piles be kept a minimum lateral distance from the crest of the slope equal to the slope height. The exposed slope face should be protected against the elements. Subgrade Preparation After vegetative layer and/or existing asphalt has been removed from the construction area, the top 10 inches of the exposed ground surface should be scarified, moisture conditioned, and recompacted to at least 95 percent of the maximum dry unit weight as determined by ASTM D698 before any new fill or foundation or pavement is placed. If pockets of soft, loose, or otherwise unsuitable materials are encountered at the bottom of the foundation excavations and it is inconvenient to lower the foundations, the proposed foundation elevations may be reestablished by over-excavating the unsuitable soils and backfilling with compacted engineered fill or lean concrete. Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 9 After the bottom of the excavation has been compacted, engineered fill can be placed to bring the building pad and pavement subgrade to the desired grade. Engineered fill should be placed in accordance with the recommendations presented in subsequent sections of this report. The stability of the subgrade may be affected by precipitation, repetitive construction traffic or other factors. If unstable conditions develop, workability may be improved by scarifying and drying. Alternatively, over-excavation of wet zones and replacement with granular materials may be used, or crushed gravel and/or rock can be tracked or “crowded” into the unstable surface soil until a stable working surface is attained. Use of lime, fly ash , cement or geosynthetics could also be considered as a stabilization technique. Laboratory evaluation is recommended to determine the effect of chemical stabilization on subgrade soils prior to construction. Lightweight excavation equipment may also be used to reduce subgrade pumping. Fill Materials The on-site soils or approved granular and low plasticity cohesive imported materials may be used as fill material. Bedrock excavated during site development and construction can be reused as fill provided the material is broken down and thoroughly processed to a “soil -like” consistency, with no particles greater than 2 inches in size. The earthwork contractor should expec t significant mechanical processing and moisture conditioning of the site soils and/or bedrock will be needed to achieve proper compaction Imported soils (if required) should meet the following material property requirements: Gradation Percent finer by weight (ASTM C136) 4” 100 3” 70-100 No. 4 Sieve 30-100 No. 200 Sieve 80 (max.) Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 10 Soil Properties Values Liquid Limit 35 (max.) Plasticity Index 15 (max.) Other import fill materials types may be suitable for use on the site depending upon proposed application and location on the site, and could be tested and approved for use on a case -by-case basis. Compaction Requirements Engineered fill should be placed and compacted in horizontal lifts, using equipment and procedures that will produce recommended moisture contents and densities throughout the lift. Item Description Fill lift thickness 9 inches or less in loose thickness when heavy, self- propelled compaction equipment is used 4 to 6 inches in loose thickness when hand-guided equipment (i.e. jumping jack or plate compactor) is used Minimum compaction requirements 95 percent of the maximum dry unit weight as determined by ASTM D698 Moisture content cohesive soil (clay) -1 to +3 % of the optimum moisture content Moisture content cohesionless soil (sand) -3 to +3 % of the optimum moisture content 1. We recommend engineered fill be tested for moisture content and compaction during placement. Should the results of the in-place density tests indicate the specified moisture or compaction limits have not been met, the area represented by the test should be reworked and retested as required until the specified moisture and compaction requirements are achieved. 2. Specifically, moisture levels should be maintained low enough to allow for satisfactory compaction to be achieved without the fill material pumping when proof rolled. 3. Moisture conditioned clay materials should not be allowed to dry out. A loss of moisture within these materials could result in an increase in the material’s expansive potential. Subsequent wetting of these materials could result in undesirable movement. Utility Trench Backfill All trench excavations should be made with sufficient working space to permit construction including backfill placement and compaction. All underground piping within or near the proposed structures should be designed with flexible couplings, so minor deviations in alignment do not result in breakage or distress. Utility knockouts in foundation walls should be oversized to accommodate differential movements. It is imperative that utility trenches be properly backfilled with relatively clean materials. If utility trenches are backfilled with relatively clean granular material, they should be capped with at least 18 inches of Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 11 cohesive fill in non-pavement areas to reduce the infiltration and conveyance of surface water through the trench backfill. Utility trenches are a common source of water infiltration and migration. All utility trenches that penetrate beneath the buildings should be effectively sealed to restrict water intrusion and flow through the trenches that could migrate below the buildings. We recommend constructing an effective clay “trench plug” that extends at least 5 feet out from the face of the building exteriors. The plug material should consist of clay compacted at a water content at or above the soil’s optimum water content. The clay fill should be placed to completely surround the utility line and be compacted in accordance with recommendations in this report. It is strongly recommended that a representative of Terracon provide full-time observation and compaction testing of trench backfill within building and pavement areas. Grading and Drainage Grades must be adjusted to provide effective drainage away from the proposed building during construction and maintained throughout the life of the proposed project. Infiltration of water into foundation excavations must be prevented during construction. Landscape irrigation adjacent to foundations should be minimized or eliminated. Water permitte d to pond near or adjacent to the perimeter of the structures (either during or post -construction) can result in significantly higher soil movements than those discussed in this report. As a result, any estimations of potential movement described in this report cannot be relied upon if positive drainage is not obtained and maintained, and water is allowed to infiltrate the fill and/or subgrade. Exposed ground (if any) should be sloped at a minimum of 10 percent grade for at least 5 feet beyond the perimeter of the proposed buildings, where possible. Locally, flatter grades may be necessary to transition ADA access requirements for flatwork. The use of swales, chases and/or area drains may be required to facilitate drainage in unpaved areas around the perimeter of the buildings. Backfill against foundations and exterior walls should be properly compacted and free of all construction debris to reduce the possibility of moisture infiltration. After construction of the proposed buildings and prior to pro ject completion, we recommend verification of final grading be performed to document positive drainage, as described above, has been achieved . Flatwork and pavements will be subject to post -construction movement. Maximum grades practical should be used f or paving and flatwork to prevent areas where water can pond. In addition, allowances in final grades should take into consideration post -construction movement of flatwork, particularly if such movement would be critical. Where paving or flatwork abuts t he structures, care should be taken that joints are properly sealed and maintained to prevent the infiltration of surface water. Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 12 Planters located adjacent to structures (if any) should preferably be self -contained. Sprinkler mains and spray heads should be located a minimum of 5 feet away from the building line(s). Low-volume, drip style landscaped irrigation should be used sparingly near the building. Roof drains should discharge on to pavements or be extended away from the structures a minimum of 10 feet through the use of splash blocks or downspout extensions. A preferred alternative is to have the roof drains discharge by solid pipe to storm sewers , a detention pond, or other appropriate outfall. Exterior Slab Design and Construction Exterior slabs on-grade, exterior architectural features, and utilities founded on, or in backfill or the site soils will likely experience some movement due to the volume change of the material. Potential movement could be reduced by: ◼ Minimizing moisture increases in the backfill; ◼ Controlling moisture-density during placement of the backfill; ◼ Using designs which allow vertical movement between the exterior features and adjoining structural elements; and ◼ Placing control joints on relatively close centers. Construction Observation and Testing The earthwork efforts should be monitored under the direction of Terracon. Monitoring should include documentation of adequate removal of vegetation and topsoil, proof rolling, and mitigation of areas delineated by the proof roll to require mitigation. Each lift of compacted fill should be tested, evaluated, and reworked as necessary until approved by Terracon prior to placement of additional lifts. In areas of foundation excavations, the bearing subgrade should be evaluated under the direction of Terracon. In the event that unanticipated conditions are encountered, Terracon should prescribe mitigation options. In addition to the documentation of the essential parameters necessary for construction, the continuation of Terracon into the construction phase of the project provides the continuity to maintain Terracon’s evaluation of subsurface conditions, including assessing variations and associated design changes. SHALLOW FOUNDATIONS If the site has been prepared in accordance with the requirements noted in Earthwork, the following design parameters are applicable for shallow foundations. Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 13 Post-Tensioned Slabs – Design Recommendations We understand the proposed buildings will be supported on post -tensioned slab foundations. Based on the subsurface conditions encountered, use of post -tensioned slabs is feasible for support of the structures provided some foundation movement can be tolerated and: ◼ The post-tensioned slab foundations are properly designed and constructed; ◼ Approved materials supporting the foundation are properly placed and compacted; ◼ Proper surface drainage is maintained throughout the life of the structures; and ◼ Prudent landscaping measures are used. In our opinion, total foundation movements on the order of about 1 inch s hould be expected. Provided foundations are properly designed, foundation movements could result in periodic, and possibly seasonal, cosmetic distress to drywall, window frames, door frames and other features. We would anticipate that the frequency of di stress and amount of movement would generally diminish with time provided proper drainage is established and/or maintained. We believe potential total foundation movements can be reduced to ½ to ¾ inch or less if at least 3 feet of imported granular engineered fill is placed directly below the post -tensioned slab foundations. The granular fill should consist of materials within the specified limits presented in the Fill Materials section of the Earthwork section this report. Based on the subsurface conditions, post-tensioned slabs should be designed using criteria presented by the Post-Tensioning Institute1 based on the following: Post-tensioned Slab Design Parameters PTI, Third Edition 2018 IBC/IRC Edge Moisture Variation Distance, em (feet) Center Lift Condition 8.5 Edge Lift Condition 4.4 Differential Soil Movement, ym (inches) Center Lift Condition -1.2 Edge Lift Condition 0.44 ◼ Maximum Net Allowable Bearing Pressure ............................................................... 2,000 psf ◼ Slab-Subgrade Friction Coefficient,  ◼ on polyethylene sheeting ................................................................................ 0.75 1 (2004, Third Edition, reprinted with 2008 Supplement), Design of Post-Tensioned Slabs-on-Ground, Post- Tensioning Institute. Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 14 ◼ on cohesionless soils ...................................................................................... 1.00 ◼ on cohesive soils............................................................................................. 2.00 The maximum net allowable bearing pressure may be increased by 1/3 for transient wind or seismic loading. It should be noted that ym is the estimated vertical movement at the edges of a uniformly loa ded slab. These are theoretical values that are used in the design of post -tensioned slabs-on-grade and do not represent the movements that would be expected from the actual loading conditions. As previously discussed, the use of post -tensioned slabs assumes that some potential movement is considered acceptable. Post-Tensioned Slabs – Construction Considerations Post-tensioned slabs, thickened or turndown edges and/or interior beams should be designed and constructed in accordance with the requirements of the PTI and the American Concrete Institute (ACI). If traditional post-tensioned slab foundations are selected, exterior slab edges should be placed a minimum of 30 inches below finished grade for frost protection. Finished grade is the lowest adjacent grade for perimeter beams. Extending exterior slab edges to depths of at least 30 inches will likely encroach upon soft to very loose and nearly saturated to wet soils requiring stabilization of subgrade prior to construction. If portions of the building floor slab will be unheated, such as patios and entryways, consideration should be given to structurally separating these areas of the slab from the remaining in terior portion of the slab. Exterior slab areas may be cantilevered portions of the slab which are subject to uplift from frost heave and swelling of the expansive soils, sometimes beyond those used for design, due to over watering of adjacent to landscap ed areas. Such movement in the exterior slabs can result in change in slab grade to the point where negative grade results and water ponds adjacent to the interior areas of the slab. Repairs of such conditions are difficult and costly, particularly if the floor slabs are post-tensioned slabs. Exterior slabs in unheated areas are subject to frost heave beneath the slab. Therefore, in design of the exterior slabs, potential movement from frost heave should be considered in the design. Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 15 It should be noted that the presences of 1 to 2-foot steps within long spans of post-tensioned slabs could create a situation where the slabs at different elevations perform independently of one another unless the steps are properly reinforced and designed to tie the slabs to gether to act as one rigid structure. We strongly recommend that joints be designed within the full height of the structure of the building over each step in order to help the structure be capable of withstanding movements on the order of 1 inch. The estimated movement should also be considered as the potential amount of tilting of the structure, which could be caused by non -uniform, significant wetting of the subsurface materials below the post-tensioned slab, resulting in potential movement. Failure to maintain soil water content below the slab and to maintain proper drainage around the structure will nullify the movement estimates provided above. If the site has been prepared in accordance with the requirements noted in Earthwork, the following design parameters are applicable for shallow foundations. Spread Footings - Design Recommendations As an alternative to post -tensioned slabs, or for other structures planned on the site, shallow spread footing foundations can be used. Description Values Bearing material Properly prepared on-site soil, or new, properly placed engineered fill. Maximum net allowable bearing pressure1 2,000 psf Minimum foundation dimensions Columns: 30 inches Continuous: 18 inches Lateral earth pressure coefficients2 Active, Ka = 0.33 Passive, Kp = 3.0 At-rest, Ko = 0.50 Sliding coefficient2 µ = 0.46 Moist soil unit weight ɣ = 120 pcf Minimum embedment depth below finished grade 3 30 inches Estimated total movement 4 About 1 inch Estimated differential movement 4 About ½ to ¾ of total movement Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 16 Description Values 1. The recommended maximum net allowable bearing pressure assumes any unsuitable fill or soft soils, if encountered, will be over-excavated and replaced with properly compacted engineered fill. The design bearing pressure applies to a dead load plus design live load condition. The design bearing pressure may be increased by one-third when considering total loads that include wind or seismic conditions 2. The lateral earth pressure coefficients and sliding coefficients are ultimate values and do not include a factor of safety. The foundation designer should include the appropriate fact ors of safety. 3. For frost protection and to reduce the effects of seasonal moisture variations in the subgrade soils. The minimum embedment depth is for perimeter footings beneath unheated areas and is relative to lowest adjacent finished grade, typically exterior grade. Interior column pads in heated areas should bear at least 12 inches below the adjacent grade (or top of the floor slab) for confinement of the bearing materials and to develop the recommended bearing pressure. 4. The estimated movements presented above are based on the assumption that the maximum footing size is 10 feet for column footings and 1.5 feet for continuous footings. Larger foundation footprints will likely require reduced net allowable soil bearing pressures to reduce risk for potential settlement. Footings should be proportioned to reduce differential foundation movement. As discussed, total movement resulting from the assumed structural loads is estimated to be on the order of about 1 inch. Additional foundation movements cou ld occur if water from any source infiltrates the foundation soils; therefore, proper drainage should be provided in the final design and during construction and throughout the life of the structure. Failure to maintain the proper drainage as recommended in the Grading and Drainage section of the Earthwork section of this report will nullify the movement estimates provided above. Spread Footings - Construction Considerations To reduce the potential of “pumping” and softening of the foundation soils at the foundation bearing level and the requirement for corrective work, we suggest the foundation excavation for the structures be completed remotely with a track-hoe operating outside of the excavation limits. Spread footing construction should only be considered if the estimated foundation movement can be tolerated. Subgrade soils beneath footings should be moisture conditioned and compacted as described in the Earthwork section of this report. The moisture content and compaction of subgrade soils should be maintained until foundation construction. Footings and foundation walls should be reinforced as necessary to reduce the potential for distress caused by differential foundation movement. Unstable subgrade conditions are anticipated as excavations approac h the groundwater surface. Unstable surfaces will need to be stabilized prior to backfilling excavations and/or constructing the building foundation, floor slab and/or project pavements. The use of angular rock, recycled concrete and/or gravel pushed or “c rowded” into the yielding subgrade is considered suitable means of stabilizing the subgrade. The use of geogrid materials in conjunction with gravel could also be considered and could be more cost effective. Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 17 Unstable subgrade conditions should be observed by Terracon to assess the subgrade and provide suitable alternatives for stabilization. Stabilized areas should be proof rolled prior to continuing construction to assess the stability of the subgrade. Foundation excavations should be observed by Terraco n. If the soil conditions encountered differ significantly from those presented in this report, supplemental recommendations will be required. SEISMIC CONSIDERATIONS The seismic design requirements for buildings and other structures are based on Seismic Design Category. Site Classification is required to determine the Seismic Design Category for a structure. The Site Classification is based on the upper 100 feet of the site profile defined by a weighted average value of either shear wave velocity, standard penetration resistance, or undrained shear strength in accordance with Section 20.4 of ASCE 7 and the International Building Code (IBC). Based on the soil/bedrock properties encountered at the site and as described on the exploration logs and results, it is our professional opinion that the Seismic Site Classification is D. Subsurface explorations at this site were extended to a maximum depth of 30 feet. The site properties below the boring depth to 100 feet were estimated based on our experience and knowledge of geologic conditions of the general area. Additional deeper borings or geophysical testing may be performed to confirm the conditions below the current boring depth. FLOOR SLABS For structures supported on a post -tensioned slab foundation system, the foundation will also function as the floor system. If a conventional spread footing is used as a foundation system, a slab on grade floor system is recommended provided the soils are over -excavated to a depth of at least 2 feet below the proposed floor slab and replaced with moisture conditioned, properly compacted engineered fill. On -site soils are suitable as over-excavation backfill below floor slabs. If the estimated movement cannot be tolerated, a structurally -supported floor system, supported independent of the subgrade materials, is recommended. Subgrade soils beneath interior and exterior slabs and at the base of the over-excavation should be scarified to a depth of at least 10 inches, moisture conditioned and compacted. The moisture content and compaction of subgrade soils should be maintained until slab construction . Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 18 Floor System - Design Recommendations Even when bearing on properly prepared soils, movement of the slab -on-grade floor system is possible should the subgrade soils undergo an i ncrease in moisture content. We estimate movement of about 1 inch is possible. If the owner cannot accept the risk of slab movement, a structural floor should be used. If conventional slab-on-grade is utilized, the subgrade soils should be over-excavated and prepared as presented in the Earthwork section of this report. For structural design of concrete slabs-on-grade subjected to point loadings, a modulus of subgrade reaction of 100 pounds per cubic inch (pci) may be used for floors supported on re - compacted existing soils at the site. A modulus of 200 pci may be used for floors supported on at least 1 foot of non-expansive, imported granular fill. Additional floor slab design and construction recommendations are as follows: ◼ Positive separations and/or isolation joints should be provided between slabs and all foundations, columns, or utility lines to allow independent movement. ◼ Control joints should be saw-cut in slabs in accordance with ACI Design Manual, Section 302.1R-37 8.3.12 (tooled control joints are not recommended) to control the location and extent of cracking. ◼ Interior utility trench backfill placed beneath slabs should be compacted in accordance with the recommendations presented in the Earthwork section of this report. ◼ Floor slabs should not be constructed on frozen subgrade. ◼ Other design and construction considerations, as outlined in the ACI Design Manual, Section 302.1R are recommended. Floor Systems - Construction Considerations Movements of slabs-on-grade using the recommendations discussed in previous sections of this report will likely be reduced and tend to be more uniform. The estimates discussed above assume that the other recommendations in this report are followed. Additional movement could occur should the subsurface soils become wetted to significant depths, which could result in potential excessive movement causing uneven floor slabs and severe cracking. This could be due to over watering of landscaping, poor drainage, improperly functioning drain systems, and/or bro ken utility lines. Therefore, it is imperative that the recommendations presented in this report be followed. Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 19 BELOW -GRADE STRUCTURES Lateral Earth Pressures Below-grade structures or reinforced concrete walls with unbalanced backfill levels on opposite sides should be designed for earth pressures at least equal to those indicated in the following table. Earth pressures will be influenced by structural design of the walls, conditions of wall restraint, methods of construction and/or compaction and the stre ngth of the materials being restrained. Two wall restraint conditions are shown. Active earth pressure is commonly used for design of free-standing cantilever retaining walls and assumes wall movement. The "at -rest" condition assumes no wall movement. The recommended design lateral earth pressures do not include a factor of safety and do not provide for possible hydrostatic pressure on the walls. Earth Pressure Coefficients Earth Pressure Conditions Coefficient for Backfill Type Equivalent Fluid Density (pcf) Surcharge Pressure, p1 (psf) Earth Pressure, p2 (psf) Active (Ka) 0.33 40 (0.33)S (40)H At-Rest (Ko) 0.50 60 (0.50)S (60)H Passive (Kp) 3.0 360 --- --- Applicable conditions to the above include: ■ For active earth pressure, wall must rotate about base, with top lateral movements of about 0.002 H to 0.004 H, where H is wall height ■ For passive earth pressure to develop, wall must move horizontally to mobilize resistance ■ Uniform surcharge, where S is surcharge pressure ■ In -situ soil backfill weight a maximum of 120 pcf ■ Horizontal backfill, compacted between 95 and 98 percent of standard Proctor maximum dry density Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 20 ■ Loading from heavy compaction equipment not included ■ No hydrostatic pressures acting on wall ■ No dynamic loading ■ No safety factor included ■ Ignore passive pressure in frost zone Backfill placed against structures should consist of granular soils or low plasticity cohesive soils. For the granular values to be valid, the granular backfill must extend out and up from the base of the wall at an angle of at least 45 and 60 degrees from vertical for the active and passive cases, respectively. To calculate the resistance to sliding, a value of 0.32 should be used as the ultimate coefficient of friction between the footing and the underlying soi l. Subsurface Drainage for Below-Grade Walls A perforated rigid plastic or metal drain line installed behind the base of walls that extend below adjacent grade is recommended to prevent hydrostatic loading on the walls. The invert of a drain line around a below-grade building area or exterior retaining wall should be placed near foundation bearing level. The drain line should be sloped to provide positive gravity drainage or to a sump pit and pump. The drain line should be surrounded by clean, free -draining granular material having less than 5 percent passing the No. 200 sieve. The free -draining aggregate should be encapsulated in a filter fabric. The granular fill should extend to within 2 feet of final grade, where it should be capped with compacted cohesive fill to reduce infiltration of surface water into the drain system. Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 21 As an alternative to free -draining granular fill, a pre -fabricated drainage structure may be used. A pre-fabricated drainage structure is a plastic drainage core or mesh which is covered with filter fabric to prevent soil intrusion, and is fastened to the wall prior to placing backfill. To control hydrostatic pressure behind the wall we recommend that a drain be installed at the foundation wall with a collection pipe leading t o a reliable discharge. If this is not possible, then combined hydrostatic and lateral earth pressures should be calculated for lean clay backfill using an equivalent fluid weighing 90 and 100 pcf for active and at -rest conditions, respectively. For granular backfill, an equivalent fluid weighing 85 and 90 pcf should be used for active and at -rest, respectively. These pressures do not include the influence of surcharge, equipment or floor loading, which should be added. Heavy equipment should not operat e within a distance closer than the exposed height of retaining walls to prevent lateral pressures more than those provided. Elevator Pit We assume an elevator pit will be included in the interior of the building. The elevator pit will likely consist of reinforced concrete walls with a concrete base slab. Based on our experience with this type of structure, we anticipate the base slabs will be about 5 feet below the level of the finished floor slab. Elevator Pit - Design Recommendation Subsurface conditions in elevator pit excavations are generally anticipated to consist of native clays and/or sands/gravels. Groundwater was encountered at depths of about 11½ to 14 ½ feet below existing site grades at the time of our field exploration. However, groundwater le vels can and should be expected to fluctuate over time. Depending upon final site grades and elevator pit elevations, groundwater could impact the performance of the pit base slab. If the pit slab is constructed at or within about 4 feet of the level of groundwater, the pit/slab should be designed and constructed to resist hydrostatic pressures and uplift due to the effects of buoyancy or it should be protected by an underdrain system for permanent dewatering. “Water-proofing” of the pit will also be need ed if permanent dewatering is not used. Terracon should evaluate the groundwater level within each elevator pit area prior to or during construction. The elevator pit walls should be designed for the lateral earth pressures imposed by the soil backfill. Earth pressures will primarily be influenced by structural design of the walls, conditions of wall restraint and type, compaction and drainage of the backfill. For purposes of design, we have assumed approximately 5 feet of fill will be retained by the pit walls and backfill will consist of the on-site lean clays. If taller walls are planned, or if different type of backfill is used, we should be contacted to review our data and confirm or modify the design criteria presented below. Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 22 Active earth pressure is commonly used for design of walls (such as free -standing cantilever retaining walls) and assumes some wall rotation and deflection. For walls that can deflect and rotate about the base, with top lateral movements of about ¼ to ½ percent or more of the wall height, lower “active” earth pressures could be considered for design. Use of the “active” condition assumes deflection and thus cracking of walls could occur. For rigid walls where negligible or very little rotation and deflection will occur, "at -rest" lateral earth pressures should be used in the design. Reinforced concrete pit walls should be designed for lateral earth pressures and/or combined hydrostatic and lateral earth pressures at least equal to those indicated in the lateral earth pressure table presented at the beginning of this section . PAVEMENTS Pavements – Subgrade Preparation On most project sites, the site grading is accomplished relatively early in the construction phase. Fills are typically placed and compacted in a uniform manner . However, as construction proceeds, the subgrade may be disturbed due to utility excavations, construction traffic, desiccation, or rainfall/snow melt. As a result, the pavement subgrade may not be suitable for pavement construction and corrective action will be required. The subgrade should be carefully evaluated at the time of pavement construction for signs of disturbance or instability. We recommend the pavement subgrade be thoroughly proof rolled with a loaded tandem-axle dump truck prior to final g rading and paving. All pavement areas should be moisture conditioned and properly compacted to the recommendations in this report immediately prior to paving. Pavements – Design Recommendations Design of new privately-maintained pavements for the project has been based on the procedures described by the National Asphalt Pavement Associations (NAPA) and the American Concrete Institute (ACI). We assumed the following design parameters for NAPA flexible pavement thickness design: ◼ Automobile Parking Areas • Class I - Parking stalls and parking lots for cars and pick -up trucks, with Equivalent Single Axle Load (ESAL) up to 7,000 over 20 years ◼ Main Traffic Corridors • Class II – Parking lots with a maximum of 10 trucks per day with Equivalent Single Axle Load (ESAL) up to 27,000 over 20 years (Including trash trucks) ◼ Subgrade Soil Characteristics Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 23 • USCS Classification – CL/ML, classified by NAPA as poor We assumed the following design parameters for ACI rigid pavement thickness design based upon the average daily truck traffic (ADTT): ◼ Automobile Parking Areas • ACI Category A: Automobile parking with an ADTT of 1 over 20 years ◼ Main Traffic Corridors • ACI Category A: Automobile parking area and service lanes with an ADTT of up to 10 over 20 years ◼ Subgrade Soil Characteristics • USCS Classification – CL/ML ◼ Concrete modulus of rupture value of 600 psi We should be contacted to confirm and/or modify the recommendations contained herein if actual traffic volumes differ from the assumed values shown above. Recommended alternatives for flexible and rigid pavements are summarized for each traffic area as follows: Traffic Area Alternative Recommended Pavement Thicknesses (Inches) Asphaltic Concrete Surface Aggregate Base Course Portland Cement Concrete Total Automobile Parking (NAPA Class I and ACI Category A) A 3½ 6 - 9½ B - - 5 5 Main Traffic Corridors (NAPA Class II and ACI Category A) A 6 6 - 12 B - - 6 6 Aggregate base course (if used on the site) should consist of a blend of sand and gravel which meets strict specifications for quality and gradation. Use of materials meeting Colorado Department of Transportation (CDOT) Class 5 or 6 specifications is recommended for aggregate base course. Aggregate base course should be placed in lifts not exceeding 6 inch es and compacted to a minimum of 95 percent of the maximum dry unit weight as determined by ASTM D698. Asphaltic concrete should be composed of a mixture of aggregate, filler and additives (if required) and approved bituminous material. The asphalt con crete should conform to approved mix Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 24 designs stating the Superpave properties, optimum asphalt content, job mix formula and recommended mixing and placing temperatures. Aggregate used in asphalt concrete should meet particular gradations. Material meeting CDOT Grading S or SX specifications or equivalent is recommended for asphalt concrete. Mix designs should be submitted prior to construction to verify their adequacy. Asphalt material should be placed in maximum 3 -inch lifts and compacted within a range of 92 to 96 percent of the theoretical maximum (Rice) density (ASTM D2041). Where rigid pavements are used, the concrete should be produced from an approved mix design with the following minimum properties: Properties Value Compressive strength 4,000 psi Cement type Type I or II portland cement Entrained air content (%) 5 to 8 Concrete aggregate ASTM C33 and CDOT section 703 Concrete should be deposited by truck mixers or agitators and placed a maximum of 90 minutes from the time the water is added to the mix. Longitudinal and transverse joints should be provided as needed in concrete pavements for expansion/contraction and isolation per ACI 325. The location and extent of joints should be based upon the final pavement geometry. For areas subject to concentrated and repetitive loading conditions (if any) such as dumpster pads, truck delivery docks and ingress/egress aprons, we recommend using a portland cement concrete pavement with a thickness of at least 6 inches underlain by at least 4 inch es of granular base. Prior to placement of the granular base, the areas should be thoroughly proof rolled. For dumpster pads, the concrete pavement area should be large enough to support the container and tipping axle of the refuse truck. Pavement performance is affected by its surroundings. In addition to providing preventive maintenance, the civil engineer should consider the following recommendations in the design and layout of pavements: ■ Site grades should slope a minimum of 2 percent away from the p avements; ■ The subgrade and the pavement surface have a minimum 2 percent slope to promote proper surface drainage; ■ Consider appropriate edge drainage and pavement under drain systems; ■ Install pavement drainage surrounding areas anticipated for frequent wetting; ■ Install joint sealant and seal cracks immediately; ■ Seal all landscaped areas in, or adjacent to pavements to reduce moisture migration to subgrade soils; and Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 25 ■ Placing compacted, low permeability backfill against the exterior side of curb and gutter. Pavements – Construction Considerations Openings in pavement, such as landscape islands, are sources for water infiltration into surrounding pavements. Water collects in the islands and migrates into the surrounding subgrade soils thereby degrading support of the pavement. This is especially applicable for islands with raised concrete curbs, irrigated foliage, and low permeability near -surface soils. The civil design for the pavements with these conditions should include features to restrict or to collect and discharge excess water from the islands. Examples of features are edge drains connected to the storm water collection system or other suitable outlet and impermeable barriers preventing lateral migration of water such as a cutoff wall installed to a d epth below the pavement structure. Pavements – Maintenance Preventative maintenance should be planned and provided for an ongoing pavement management program in order to enhance future pavement performance. Preventive maintenance consists of both localiz ed maintenance (e.g. crack and joint sealing and patching) and global maintenance (e.g. surface sealing). Preventative maintenance is usually the first priority when implementing a planned pavement maintenance program and provides the highest return on investment for pavements. FROST CONSIDERATIONS The soils on this site are frost susceptible, and small amounts of water can affect the performance of the slabs on-grade, sidewalks, and pavements. Exterior slabs should be anticipated to heave during winter months. If frost action needs to be eliminated in critical areas, we recommend the use of non-frost susceptible (NFS) fill or structural slabs (for instance, structural stoops in front of building doors). Placement of NFS material in large areas may not be feasible; however, the following recommendations are provided to help reduce potential frost heave: ■ Provide surface drainage away from the building and slabs, and toward the site storm drainage system. ■ Install drains around the perimeter of the building, stoops, below exterior slabs and pavements, and connect them to the storm drainage system . ■ Grade clayey subgrades, so groundwater potentially perched in overlying more permeable subgrades, such as sand or aggregate base, slope toward a site drainage system . ■ Place NFS fill as backfill beneath slabs and pavements critical to the project . ■ Place a 3 horizontal to 1 vertical (3H:1V) transition zone between NFS fill and other soils. ■ Place NFS materials in critical sidewalk areas. Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 26 As an alternative to extending NFS fill to the full frost depth, consideration can be made to placing extruded polystyrene or cellular concrete under a buffer of at least 2 feet of NFS material. CORROSIVITY At the time this report was prepared, the laboratory testing for water -soluble sulfates had not been completed. We will submit a supplemental section with the testing results and recommendations once the testing has been completed. GENERAL COMMENTS Our analysis and opinions are based upon our understanding of the project, the geotechnical conditions in the area, and the data obtained from our site exploration. Natural variations will occur between exploration point locations or due to the modifying effec ts of construction or weather. The nature and extent of such variations may not beco me evident until during or after construction. Terracon should be retained as the Geotechnical Engineer, where noted in th is report, to provide observation and testing services during pertinent construction phases. If variations appear, we can provide further evaluation and supplemental recommendations. If variations are noted in the absence of our observation and testing services on -site, we should be immediately notified so that we can provide evaluation and supplemental recommendations. Our Scope of Services does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken. Our services and any correspondence or collaboration through this system are intended for the sole benefit and exclusive use of our client for specific application to the project discussed and are accomplished in accordance with generally accepted geotechnical engineering practices with no third-party beneficiaries intended. Any third-party access to services or correspondence is solely for information purposes to support the services provided by Terracon to our client. Reliance upon the services and any work product is limited to our client, and is not intended for third parties. Any use or reliance of the provided information by third parties is done solely at thei r own risk. No warranties, either express or implied, are intended or made. Site characteristics as provided are for design purposes and not to estimate excavation cost. Any use of our report in that regard is done at the sole risk of the excavating cost estimator as there may be variations on the site that are not apparent in the data that could significantly impact excavation cost. Any parties charged with estimating excavation costs should seek their own site characterization for specific purposes to obtain the specific level of detail necessary for costing. Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable 27 Site safety, and cost estimating including, excavation support, and dewatering requirements/design are the responsibility of others. If changes in the nature, design, or location of the project are planned, our conclusions and recommendations shall not be considered valid unless we review the changes and either verify or modify our conclusions in writing. Responsive ■ Resourceful ■ Reliable ATTACHMENTS Contents: EXPLORATION AND TESTING PROCEDURES SITE LOCATION AND EXPLORATION PLANS EXPLORATION RESULTS SUPPORTING INFORMATION Note: Refer to each individual Attachment for a listing of contents. Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable EXPLORATION AND TESTING PROCEDURES 1 of 2 EXPLORATION AND TESTING PROCEDURES Field Exploration The field exploration program consist ed of the following: Number of Borings Boring Depth (feet) 1 Location 7 25 to 30 or auger refusal Planned building areas Boring Layout and Elevations: We used handheld GPS equipment to locate borings with an estimated horizontal accuracy of +/-20 feet. A ground surface elevation at each boring location was obtained by interpolation from a provided site specific, surveyed topographic map. Subsurface Exploration Procedures: We advanced soil borings with a truck-mounted drill rig using solid-stem, continuous-flight augers. Three samples were obtained in the upper 10 feet of each boring and at intervals of 5 feet thereafter. Soil sampling was performed using modified California barrel and standard split -barrel sampling procedures. For the standard split -barrel sampling procedure, a standard 2 -inch outer diameter split-barrel sampling spoon is driven into the ground by a 140 -pound automatic hammer falling a distance of 30 inches. The number of blows required to advance the sampling spoon the last 12 inches of a normal 18 -inch penetration is recorded as the Standard Penetration Test (SPT) resistance value. The SPT resistance values, also referred to as N-values, are indicated on the boring logs at the test depths. For the modified California barrel sampling procedure, a 2½-inch outer diameter split-barrel sampling spoon is used for sampling. Modified California barrel sampling procedures are similar to standard split - barrel sampling procedures; however, blow counts are typically recorded for 6 -inch intervals for a total of 12 inches of penetration. The samples were placed in appropriate containers, taken to our soil laboratory for testing, and classified by a geotechnical engineer. In addition, we observed and recorded groundwater levels during drilling observations. No provisions were made to obtain delayed groundwater measurements. Our exploration team prepared field boring logs as part of standard drilling operations including sampling depths, penetration distances, and other relevant sampling information. Field logs will include visual classifications of materials encountered during drilling, and our interpretation of subsurface conditions between samples. Final boring logs, prepared from field logs, represent the geotechnical engineer's interpretation, and include modifications based on observations an d laboratory test results. Property Disturbance: We backfilled borings with auger cuttings after completion. Borings completed in pavement areas were backfilled with auger cuttings and patched with asphalt, as Geotechnical Engineering Report Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Responsive ■ Resourceful ■ Reliable EXPLORATION AND TESTING PROCEDURES 2 of 2 appropriate. Our services did not include repair of the site beyond backfilling our boreholes, and patching existing pavements. Excess auger cuttings were dispersed in the general vicinity of the boreholes. Because backfill material often settles below the surface after a period, we recommend checking boreholes periodically and backfilling, if necessary. We can provide this service, for additional fees, at your request. Laboratory Testing The project engineer reviewed field data and assigned various laboratory tests to better understand the engineerin g properties of various soil and bedrock strata. Laboratory testing was conducted in general accordance with applicable or other locally recognized standards. Procedural standards noted in this report are for reference to methodology in general. In some cases, variations to methods are applied as a result of local practice or professional judgement. Testing was performed under the direction of a geotechnical engineer and included the following: ■ Visual classification ■ Moisture content ■ Dry density ■ Atterberg limits ■ Grain-size analysis ■ One-dimensional swell ■ hydrometer ■ Unconfined compressive strength ■ Water-soluble sulfates Our laboratory testing program includes examination of soil samples by an engineer. Based on the material’s texture and plasticity, we described and classified soil samples in accordance with the Unified Soil Classification System (USCS). Soil and bedrock samples obtained during our field work will be disposed of after laboratory testing is complete unless a specific request is made to temporarily store the samples for a longer period of time. Bedrock samples obtained had rock classification conducted using locally accepted practices for engineering purposes. Boring log rock classification is determined using the Description of Rock Properties. Responsive ■ Resourceful ■ Reliable SITE LOCATION AND EXPLORATION PLANS Contents: Site Location Plan Exploration Plan Note: All attachments are one page unless noted above. SITE LOCATION Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Note to Preparer: This is a large table with outside borders. Just click inside the table above this text box, then paste your GIS Toolbox image. When paragraph markers are turned on you may notice a line of hidden text above and outside the table – please leave that alone. Limit editing to inside the table. The line at the bottom about the general location is a separate table line. You can edit it as desired, but try to keep to a single line of text to avoid reformatting the page. SITE LOCA TION DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS EXPLORATION PLAN Timberline Apartments ■ Fort Collins, Colorado May 5, 2021 ■ Terracon Project No. 20215032 Note to Preparer: This is a large table with outside borders. Just click inside the table above this text box, then paste your GIS Toolbox image. When paragraph markers are turned on you may notice a line of hidden text above and outside the table – please leave that alone. Limit editing to inside the table. The line at the bottom about the general location is a separate table line. You can edit it as desired, but try to keep to a single line of text to avoid reformatting the page. EXPLORATION P LAN DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS EXPLORATION RESULTS Contents: GeoModel Boring Logs (7 pages) Atterberg Limits Grain Size Distribution (2 pages) Consolidation/Swell (4 pages) Unconfined Compressive Strength (4 pages) Note: All attachments are one page unless noted above. 4,895 4,900 4,905 4,910 4,915 4,920 4,925 4,930 4,935 ELEVATION(MSL)(feet)Timberline Apartments Fort Collins, CO Terracon Project No. 20215032 Layering shown on this figure has been developed by the geotechnical engineer for purposes of modeling the subsurface conditions as required for the subsequent geotechnical engineering for this project. Numbers adjacent to soil column indicate depth below ground surface. NOTES: 1 2 3 4 5 6 7 GEOMODEL This is not a cross section. This is intended to display the Geotechnical Model only. See individual logs for more detailed conditions. Groundwater levels are temporal. The levels shown are representative of the date and time of our exploration. Significant changes are possible over time. Water levels shown are as measured during and/or after drilling. In some cases, boring advancement methods mask the presence/absence of groundwater. See individual logs for details. First Water Observation Poorly graded gravel with sand, brown to red brown, dense to very dense3 Claystone bedrock, weathered zone in the upper 6 inches to 2 feet, light brown with orange and gray in weathered zone, gray to dark gray and very hard in competent bedrock 4 LEGEND Asphalt Sandy Silt Poorly-graded Gravel with Sand Weathered Rock Bedrock Vegetative Layer Sandy Lean Clay Sandy Elastic Silt Lean Clay with Sand Aggregate Base Course Clayey Sand Model Layer General DescriptionLayer Name Sandy silt to sandy elastic silt, brown to dark brown, light brown/orange brown and tan, soft to very stiff1 Lean clay with varying amounts of sand and trace amounts of gravel, brown to red brown with light gray, medium stiff to very stiff 2 SAND AND GRAVEL BEDROCK SILT LEAN CLAY 12 20.5 24.4 1 3 4 12 3 9.5 21 29.4 2 1 3 4 12 10 19 24.5 1 3 4 12 12 20.5 21 24.4 1 3 4 3 13 12 18 29.4 2 3 4 13 12 18 24.5 2 3 4 12 13 17 24.4 2 3 4 13 2-2-2 N=4 4-5 5-7-10 N=17 7-12 7-10-15 N=25 50/4" no recovery - grab of auger cuttings 0/500 63 16.4 17.6 17.8 8.5 8.1 18.7 107 129 49-30-19 ASPHALT, approximately 4 inches SANDY SILT (ML), soft to medium stiff, varies to lean clay with varying amounts of sand brown brown to light brown light brown to tan, very stiff POORLY GRADED GRAVEL WITH SAND, brown to red brown, medium dense WEATHERED CLAYSTONE, light brown with orange and gray, weathered CLAYSTONE, gray to dark gray, hard to very hard Boring Terminated at 24.4 Feet 0.4 12.0 20.5 22.0 24.4 4930.5 4919 4910.5 4909 4906.5 Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.THISBORINGLOGISNOTVALIDIFSEPARATEDFROMORIGINALREPORT.GEOSMARTLOG-NOWELL20215032TIMBERLINEAPARTM.GPJTERRACON_DATATEMPLATE.GDT5/5/21WATERLEVELOBSERVATIONSDEPTH(Ft.)5 10 15 20 FIELDTESTRESULTSSWELL/LOAD(%/psf)UNCONFINEDCOMPRESSIVESTRENGTH(psf)PERCENTFINESWATERCONTENT(%)DRYUNITWEIGHT(pcf)ATTERBERG LIMITS LL-PL-PI LOCATION See Exploration Plan Latitude: 40.5458° Longitude: -105.0372°GRAPHICLOGMODELLAYERDEPTH ELEVATION (Ft.) Surface Elev.: 4931 (Ft.) Page 1 of 1 Advancement Method: 4-inch diameter, solid-stem augers Abandonment Method: Backfilled with auger cuttings and patched with asphalt to match existing surfaces Notes: Project No.: 20215032 Drill Rig: CME-55 BORING LOG NO. 1 Tetrad Property Group LLCCLIENT: Fort Collins, CO Driller: Drilling Engineers, Inc. Boring Completed: 04-23-2021 PROJECT: Timberline Apartments Elevations were interpolated from a topographic site plan. See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any). See Supporting Information for explanation of symbols and abbreviations. 2908 S Timberline Road Fort Collins, CO SITE: Boring Started: 04-23-2021 1901 Sharp Point Dr Ste C Fort Collins, CO 12' while drilling WATER LEVEL OBSERVATIONS 1 3 4 SAMPLETYPE 10-15 7-8-10 N=18 6-9 22-38-31 N=69 12-26-20 N=46 skipped sample to keep hole open with flowing sands 50/5" -0.1/1,000 65 0 10.1 14.5 7.1 13.7 10.7 17.0 101 124 33-17-16 NP NATIVE GRASSES AND WEEDS, approximately 6 inches SANDY LEAN CLAY (CL), trace gravel, brown, very stiff SANDY SILT, brown, very stiff, varies to lean clay with varying amounts of sand POORLY GRADED GRAVEL WITH SAND (GP), brown to red brown, dense to very dense CLAYSTONE, gray to dark gray, hard to very hard Boring Terminated at 29.4 Feet 0.5 3.0 9.5 21.0 29.4 4930.5 4928 4921.5 4910 4901.5 Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.THISBORINGLOGISNOTVALIDIFSEPARATEDFROMORIGINALREPORT.GEOSMARTLOG-NOWELL20215032TIMBERLINEAPARTM.GPJTERRACON_DATATEMPLATE.GDT5/5/21WATERLEVELOBSERVATIONSPROJECT: Timberline Apartments Elevations were interpolated from a topographic site plan. See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any). See Supporting Information for explanation of symbols and abbreviations. 2908 S Timberline Road Fort Collins, CO SITE: Boring Started: 04-23-2021 1901 Sharp Point Dr Ste C Fort Collins, CO 12' while drilling WATER LEVEL OBSERVATIONS DEPTH(Ft.)5 10 15 20 25 FIELDTESTRESULTSSWELL/LOAD(%/psf)UNCONFINEDCOMPRESSIVESTRENGTH(psf)PERCENTFINESWATERCONTENT(%)DRYUNITWEIGHT(pcf)ATTERBERG LIMITS LL-PL-PI LOCATION See Exploration Plan Latitude: 40.5460° Longitude: -105.0358°GRAPHICLOGMODELLAYERDEPTH ELEVATION (Ft.) Surface Elev.: 4931 (Ft.) Page 1 of 1 Advancement Method: 4-inch diameter, solid-stem augers Abandonment Method: Backfilled with auger cuttings Notes: Project No.: 20215032 Drill Rig: CME-55 BORING LOG NO. 2 Tetrad Property Group LLCCLIENT: Fort Collins, CO Driller: Drilling Engineers, Inc. Boring Completed: 04-23-2021 2 1 3 4 SAMPLETYPE 3-4-3 N=7 3-5 18-33-31 N=64 11-50/5" skipped sample to keep hole open with flowing sands 50/6" 3280 60 16.6 18.8 6.9 10.0 18.2 46-30-16 NATIVE GRASSES AND WEEDS, approximately 3 inches SANDY SILT (ML), brown to dark brown, medium stiff, varies to lean clay with varying amounts of sand trace organics POORLY GRADED GRAVEL WITH SAND, brown to red brown, dense to very dense CLAYSTONE, light brown with gray and orange to gray, hard to very hard Boring Terminated at 24.5 Feet 0.3 10.0 19.0 24.5 4927.5 4918 4909 4903.5 106 Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.THISBORINGLOGISNOTVALIDIFSEPARATEDFROMORIGINALREPORT.GEOSMARTLOG-NOWELL20215032TIMBERLINEAPARTM.GPJTERRACON_DATATEMPLATE.GDT5/5/21WATERLEVELOBSERVATIONSDEPTH(Ft.)5 10 15 20 FIELDTESTRESULTSSWELL/LOAD(%/psf)UNCONFINEDCOMPRESSIVESTRENGTH(psf)PERCENTFINESWATERCONTENT(%)DRYUNITWEIGHT(pcf)LOCATION See Exploration Plan Latitude: 40.5464° Longitude: -105.0358°GRAPHICLOGMODELLAYERDEPTH ELEVATION (Ft.) Surface Elev.: 4928 (Ft.) Page 1 of 1 Advancement Method: 4-inch diameter, solid-stem augers Abandonment Method: Backfilled with auger cuttings Notes: Project No.: 20215032 Drill Rig: CME-55 BORING LOG NO. 3 Tetrad Property Group LLCCLIENT: ATTERBERG LIMITS LL-PL-PI Fort Collins, CO Driller: Drilling Engineers, Inc. Boring Completed: 04-23-2021 PROJECT: Timberline Apartments Elevations were interpolated from a topographic site plan. See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any). See Supporting Information for explanation of symbols and abbreviations. 2908 S Timberline Road Fort Collins, CO SITE: Boring Started: 04-23-2021 1901 Sharp Point Dr Ste C Fort Collins, CO 12' while drilling WATER LEVEL OBSERVATIONS 1 3 4 SAMPLETYPE 7-16 6-8-8 N=16 1-2 22-30-35 N=65 no recovery 22-19-15 N=34 50/5" 940 58 14.1 21.3 18.0 15.5 11.0 114 105 50-29-21 NATIVE GRASSES AND WEEDS, approximately 3 inches SANDY ELASTIC SILT (MH), brown, very stiff, varies to lean clay with varying amounts of sand light brown to orange brown, soft POORLY GRADED GRAVEL WITH SAND, brown to red brown, dense to very dense WEATHERED CLAYSTONE, light brown, weathered CLAYSTONE, gray to dark gray, hard to very hard Boring Terminated at 24.4 Feet 0.3 12.0 20.5 21.0 24.4 4929.5 4918 4909.5 4909 4905.5 Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.THISBORINGLOGISNOTVALIDIFSEPARATEDFROMORIGINALREPORT.GEOSMARTLOG-NOWELL20215032TIMBERLINEAPARTM.GPJTERRACON_DATATEMPLATE.GDT5/5/21WATERLEVELOBSERVATIONSDEPTH(Ft.)5 10 15 20 FIELDTESTRESULTSSWELL/LOAD(%/psf)PROJECT: Timberline Apartments Elevations were interpolated from a topographic site plan. See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any). See Supporting Information for explanation of symbols and abbreviations. 2908 S Timberline Road Fort Collins, CO SITE: Boring Started: 04-23-2021 1901 Sharp Point Dr Ste C Fort Collins, CO 13' while drilling WATER LEVEL OBSERVATIONS UNCONFINEDCOMPRESSIVESTRENGTH(psf)PERCENTFINESWATERCONTENT(%)DRYUNITWEIGHT(pcf)ATTERBERG LIMITS LL-PL-PI LOCATION See Exploration Plan Latitude: 40.5472° Longitude: -105.0348°GRAPHICLOGMODELLAYERDEPTH ELEVATION (Ft.) Surface Elev.: 4930 (Ft.) Page 1 of 1 Advancement Method: 4-inch diameter, solid-stem augers Abandonment Method: Backfilled with auger cuttings Notes: Project No.: 20215032 Drill Rig: CME-55 BORING LOG NO. 4 Tetrad Property Group LLCCLIENT: Fort Collins, CO Driller: Drilling Engineers, Inc. Boring Completed: 04-23-2021 1 3 4 3 SAMPLETYPE 7-13-15 N=28 10-15 3-4-5 N=9 16-50/5" skipped sample to keep hole open with flowing sands skipped sample to keep hole open with flowing sands 50/5" +0.1/500 8160 78 100 12.4 16.1 17.9 9.3 14.4 114 106 44-15-29 42-21-21 NATIVE GRASSES AND WEEDS, approximately 3 inches SANDY LEAN CLAY, trace gravel, brown, very stiff LEAN CLAY WITH SAND (CL), red brown with light gray/white, medium stiff POORLY GRADED GRAVEL WITH SAND, brown to red brown, dense to very dense CLAYSTONE (CL), gray to dark gray, hard to very hard Boring Terminated at 29.4 Feet 0.3 4.5 12.0 18.0 29.4 4927.5 4923.5 4916 4910 4898.5 Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.THISBORINGLOGISNOTVALIDIFSEPARATEDFROMORIGINALREPORT.GEOSMARTLOG-NOWELL20215032TIMBERLINEAPARTM.GPJTERRACON_DATATEMPLATE.GDT5/5/21WATERLEVELOBSERVATIONSDEPTH(Ft.)5 10 15 20 25 FIELDTESTRESULTSSWELL/LOAD(%/psf)UNCONFINEDCOMPRESSIVESTRENGTH(psf)PERCENTFINESWATERCONTENT(%)DRYUNITWEIGHT(pcf)ATTERBERG LIMITS LL-PL-PI LOCATION See Exploration Plan Latitude: 40.5476° Longitude: -105.0349°GRAPHICLOGMODELLAYERDEPTH ELEVATION (Ft.) Surface Elev.: 4928 (Ft.) Page 1 of 1 Advancement Method: 4-inch diameter, solid-stem augers Abandonment Method: Backfilled with auger cuttings Notes: Project No.: 20215032 Drill Rig: CME-55 BORING LOG NO. 5 Tetrad Property Group LLCCLIENT: Fort Collins, CO Driller: Drilling Engineers, Inc. Boring Completed: 04-23-2021 PROJECT: Timberline Apartments Elevations were interpolated from a topographic site plan. See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any). See Supporting Information for explanation of symbols and abbreviations. 2908 S Timberline Road Fort Collins, CO SITE: Boring Started: 04-23-2021 1901 Sharp Point Dr Ste C Fort Collins, CO 13' while drilling WATER LEVEL OBSERVATIONS 2 3 4 SAMPLETYPE 9-11 5-4-3 N=7 4-3 50/6" 13-17-26 N=43 50/6" +0.4/1,000 57 11.1 12.3 21.0 9.0 28.5 17.9 93 111 111 36-18-18 NATIVE GRASSES AND WEEDS, approximately 3 inches SANDY LEAN CLAY (CL), red brown with light gray/white, very stiff medium stiff POORLY GRADED GRAVEL WITH SAND, brown to red brown, very dense CLAYSTONE gray to tan, medium hard dark gray, hard to very hard Boring Terminated at 24.5 Feet 0.3 12.0 18.0 24.5 4928.5 4917 4911 4904.5 Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.THISBORINGLOGISNOTVALIDIFSEPARATEDFROMORIGINALREPORT.GEOSMARTLOG-NOWELL20215032TIMBERLINEAPARTM.GPJTERRACON_DATATEMPLATE.GDT5/5/21WATERLEVELOBSERVATIONSDEPTH(Ft.)5 10 15 20 FIELDTESTRESULTSSWELL/LOAD(%/psf)UNCONFINEDCOMPRESSIVESTRENGTH(psf)PERCENTFINESWATERCONTENT(%)DRYUNITWEIGHT(pcf)ATTERBERG LIMITS LL-PL-PI LOCATION See Exploration Plan Latitude: 40.5482° Longitude: -105.0346°GRAPHICLOGMODELLAYERDEPTH ELEVATION (Ft.) Surface Elev.: 4929 (Ft.) Page 1 of 1 Advancement Method: 4-inch diameter, solid-stem augers Abandonment Method: Backfilled with auger cuttings Notes: Project No.: 20215032 Drill Rig: CME-55 BORING LOG NO. 6 Tetrad Property Group LLCCLIENT: Fort Collins, CO Driller: Drilling Engineers, Inc. Boring Completed: 04-23-2021 PROJECT: Timberline Apartments Elevations were interpolated from a topographic site plan. See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any). See Supporting Information for explanation of symbols and abbreviations. 2908 S Timberline Road Fort Collins, CO SITE: Boring Started: 04-23-2021 1901 Sharp Point Dr Ste C Fort Collins, CO 12' while drilling WATER LEVEL OBSERVATIONS 2 3 4 SAMPLETYPE 4-5-5 N=10 4-6 6-9-10 N=19 20-25-35 N=60 28-50/3" 50/5" 2590 48 19.7 17.0 14.2 10.8 19.4 16.0 111 105 33-15-18 AGGREGATE BASE COURSE, approximately 5 inches CLAYEY SAND (SC), red brown with light gray/white, medium dense trace gravel, light brown to tan POORLY GRADED GRAVEL WITH SAND, brown to red brown, very dense CLAYSTONE, hard to very hard gray with tan gray to dark gray Boring Terminated at 24.4 Feet 0.4 13.0 17.0 24.4 4929.5 4917 4913 4905.5 Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.THISBORINGLOGISNOTVALIDIFSEPARATEDFROMORIGINALREPORT.GEOSMARTLOG-NOWELL20215032TIMBERLINEAPARTM.GPJTERRACON_DATATEMPLATE.GDT5/5/21WATERLEVELOBSERVATIONSDEPTH(Ft.)5 10 15 20 FIELDTESTRESULTSSWELL/LOAD(%/psf)UNCONFINEDCOMPRESSIVESTRENGTH(psf)PERCENTFINESWATERCONTENT(%)DRYUNITWEIGHT(pcf)ATTERBERG LIMITS LL-PL-PI LOCATION See Exploration Plan Latitude: 40.5484° Longitude: -105.0350°GRAPHICLOGMODELLAYERDEPTH ELEVATION (Ft.) Surface Elev.: 4930 (Ft.) Page 1 of 1 Advancement Method: 4-inch diameter, solid-stem augers Abandonment Method: Backfilled with auger cuttings Notes: Project No.: 20215032 Drill Rig: CME-55 BORING LOG NO. 7 Tetrad Property Group LLCCLIENT: Fort Collins, CO Driller: Drilling Engineers, Inc. Boring Completed: 04-23-2021 PROJECT: Timberline Apartments Elevations were interpolated from a topographic site plan. See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any). See Supporting Information for explanation of symbols and abbreviations. 2908 S Timberline Road Fort Collins, CO SITE: Boring Started: 04-23-2021 1901 Sharp Point Dr Ste C Fort Collins, CO 13' while drilling WATER LEVEL OBSERVATIONS 2 3 4 SAMPLETYPE 0 10 20 30 40 50 60 0 20 40 60 80 100CHorOHCLorOLML or OL MH or OH"U"Line"A "LineATTERBERG LIMITS RESULTS ASTM D4318 P L A S T I C I T Y I N D E X LIQUID LIMIT PROJECT NUMBER: 20215032 SITE: 2908 S Timberline Road Fort Collins, CO PROJECT: Timberline Apartments CLIENT: Tetrad Property Group LLC Fort Collins, CO 1901 Sharp Point Dr Ste C Fort Collins, CO LABORATORYTESTSARENOTVALIDIFSEPARATEDFROMORIGINALREPORT.ATTERBERGLIMITS20215032TIMBERLINEAPARTM.GPJTERRACON_DATATEMPLATE.GDT5/4/2149 33 NP 46 50 44 42 36 33 30 17 NP 30 29 15 21 18 15 19 16 NP 16 21 29 21 18 18 PIPLLLBoring ID Depth 1 2 2 3 4 5 5 6 7 62.7 64.7 0.2 59.9 58.4 78.4 99.6 56.6 48.2 Fines 4 - 5 2 - 3 14 - 15.5 4 - 5 9 - 10 9 - 10.5 29 - 29.4 4 - 5.5 4 - 5 ML CL GP ML MH CL CL CL SC SANDY SILT SANDY LEAN CLAY POORLY GRADED GRAVEL with SAND SANDY SILT SANDY ELASTIC SILT LEAN CLAY with SAND CLAYSTONE SANDY LEAN CLAY CLAYEY SAND DescriptionUSCS CL-ML 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 0.0010.010.1110100 30 40 501.5 200681014413/4 1/2 60 GRAIN SIZE IN MILLIMETERSPERCENTFINERBYWEIGHT HYDROMETERU.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS 4 3/8 3 100 14032 GRAIN SIZE DISTRIBUTION ASTM D422 / ASTM C136 6 16 20 PROJECT NUMBER: 20215032 SITE: 2908 S Timberline Road Fort Collins, CO PROJECT: Timberline Apartments CLIENT: Tetrad Property Group LLC Fort Collins, CO 1901 Sharp Point Dr Ste C Fort Collins, CO LABORATORYTESTSARENOTVALIDIFSEPARATEDFROMORIGINALREPORT.GRAINSIZE:USCS-220215032TIMBERLINEAPARTM.GPJTERRACON_DATATEMPLATE.GDT5/4/21mediumcoarsecoarsefine fineCOBBLESGRAVELSAND SILT OR CLAY 1 2 2 3 4 SANDY SILT (ML) SANDY LEAN CLAY (CL) POORLY GRADED GRAVEL with SAND (GP) SANDY SILT (ML) SANDY ELASTIC SILT (MH) 49 33 NP 46 50 0.46 19 16 NP 16 21 30 17 NP 30 29 27.74 4 - 5 2 - 3 14 - 15.5 4 - 5 9 - 10 17.6 10.1 13.7 18.8 18.0 1 2 2 3 4 64.7 0.2 59.9 58.4 45.217.54 - 5 2 - 3 14 - 15.5 4 - 5 9 - 10 1.3 1.2 54.1 10.5 2.1 36.0 34.1 45.7 29.6 39.5 9.5 9.5 37.5 25 9.5 0.017 11.964 0.076 0.083 1.536 0.431 Boring ID Depth WC (%)LL PL PI Cc Cu %Clay%Fines%Silt%Sand%Gravel Boring ID Depth D100 D60 D30 D10 USCS Classification %Cobbles 0.0 0.0 0.0 0.0 0.0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 0.0010.010.1110100 30 40 501.5 200681014413/4 1/2 60 GRAIN SIZE IN MILLIMETERSPERCENTFINERBYWEIGHT HYDROMETERU.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS 4 3/8 3 100 14032 GRAIN SIZE DISTRIBUTION ASTM D422 / ASTM C136 6 16 20 PROJECT NUMBER: 20215032 SITE: 2908 S Timberline Road Fort Collins, CO PROJECT: Timberline Apartments CLIENT: Tetrad Property Group LLC Fort Collins, CO 1901 Sharp Point Dr Ste C Fort Collins, CO LABORATORYTESTSARENOTVALIDIFSEPARATEDFROMORIGINALREPORT.GRAINSIZE:USCS-220215032TIMBERLINEAPARTM.GPJTERRACON_DATATEMPLATE.GDT5/4/21mediumcoarsecoarsefine fineCOBBLESGRAVELSAND SILT OR CLAY 5 5 6 7 LEAN CLAY with SAND (CL) CLAYSTONE (CL) SANDY LEAN CLAY (CL) CLAYEY SAND (SC) 44 42 36 33 29 21 18 18 15 21 18 15 9 - 10.5 29 - 29.4 4 - 5.5 4 - 5 17.9 14.4 12.3 17.0 5 5 6 7 78.4 99.6 56.6 28.719.5 9 - 10.5 29 - 29.4 4 - 5.5 4 - 5 0.1 0.0 0.0 0.7 21.6 0.4 43.4 51.2 9.5 2 4.75 9.5 0.09 0.152 0.006 Boring ID Depth WC (%)LL PL PI Cc Cu %Clay%Fines%Silt%Sand%Gravel Boring ID Depth D100 D60 D30 D10 USCS Classification %Cobbles 0.0 0.0 0.0 0.0 -10 -8 -6 -4 -2 0 2 4 100 1,000 10,000AXIALSTRAIN,%PRESSURE, psf NOTES: Sample exhibited no movement upon wetting under an applied pressure of 500 psf. SWELL CONSOLIDATION TEST ASTM D4546 PROJECT NUMBER: 20215032 SITE: 2908 S Timberline Road Fort Collins, CO PROJECT: Timberline Apartments CLIENT: Tetrad Property Group LLC Fort Collins, CO 1901 Sharp Point Dr Ste C Fort Collins, CO LABORATORYTESTSARENOTVALIDIFSEPARATEDFROMORIGINALREPORT.TC_CONSOL_STRAIN-USCS20215032TIMBERLINEAPARTM.GPJTERRACON_DATATEMPLATE.GDT5/5/211 SANDY SILT(ML)4 - 5 ft 108 16.4 Specimen Identification Classification , pcf WC, % -10 -8 -6 -4 -2 0 2 4 100 1,000 10,000AXIALSTRAIN,%PRESSURE, psf NOTES: Sample exhibited 0.1 percent compression upon wetting under an applied pressure of 1,000 psf. SWELL CONSOLIDATION TEST ASTM D4546 PROJECT NUMBER: 20215032 SITE: 2908 S Timberline Road Fort Collins, CO PROJECT: Timberline Apartments CLIENT: Tetrad Property Group LLC Fort Collins, CO 1901 Sharp Point Dr Ste C Fort Collins, CO LABORATORYTESTSARENOTVALIDIFSEPARATEDFROMORIGINALREPORT.TC_CONSOL_STRAIN-USCS20215032TIMBERLINEAPARTM.GPJTERRACON_DATATEMPLATE.GDT5/5/212 SANDY SILT9 - 10 ft 124 7.1 Specimen Identification Classification , pcf WC, % -10 -8 -6 -4 -2 0 2 4 100 1,000 10,000AXIALSTRAIN,%PRESSURE, psf NOTES: Sample exhibited 0.1 percent swell upon wetting under an applied pressure of 500 psf. SWELL CONSOLIDATION TEST ASTM D4546 PROJECT NUMBER: 20215032 SITE: 2908 S Timberline Road Fort Collins, CO PROJECT: Timberline Apartments CLIENT: Tetrad Property Group LLC Fort Collins, CO 1901 Sharp Point Dr Ste C Fort Collins, CO LABORATORYTESTSARENOTVALIDIFSEPARATEDFROMORIGINALREPORT.TC_CONSOL_STRAIN-USCS20215032TIMBERLINEAPARTM.GPJTERRACON_DATATEMPLATE.GDT5/5/215 LEAN CLAY WITH SAND4 - 5 ft 114 16.1 Specimen Identification Classification , pcf WC, % -10 -8 -6 -4 -2 0 2 4 100 1,000 10,000AXIALSTRAIN,%PRESSURE, psf NOTES: Sample exhibited 0.4 percent swell upon wetting under an applied pressure of 1,000 psf. SWELL CONSOLIDATION TEST ASTM D4546 PROJECT NUMBER: 20215032 SITE: 2908 S Timberline Road Fort Collins, CO PROJECT: Timberline Apartments CLIENT: Tetrad Property Group LLC Fort Collins, CO 1901 Sharp Point Dr Ste C Fort Collins, CO LABORATORYTESTSARENOTVALIDIFSEPARATEDFROMORIGINALREPORT.TC_CONSOL_STRAIN-USCS20215032TIMBERLINEAPARTM.GPJTERRACON_DATATEMPLATE.GDT5/5/216 SANDY LEAN CLAY9 - 10 ft 111 21.0 Specimen Identification Classification , pcf WC, % 0 500 1,000 1,500 2,000 2,500 3,000 3,500 0 2 4 6 8 10 AXIAL STRAIN - % UNCONFINED COMPRESSION TEST ASTM D2166 COMPRESSIVESTRESS-psfPROJECT NUMBER: 20215032 SITE: 2908 S Timberline Road Fort Collins, CO PROJECT: Timberline Apartments CLIENT: Tetrad Property Group LLC Fort Collins, CO 1901 Sharp Point Dr Ste C Fort Collins, CO LABORATORYTESTSARENOTVALIDIFSEPARATEDFROMORIGINALREPORT.UNCONFINEDWITHPHOTOS20215032TIMBERLINEAPARTM.GPJTERRACON_DATATEMPLATE.GDT5/4/21SAMPLE LOCATION:3 @ 4 - 5 feetSAMPLE TYPE: CARS 0.58 86.99 106 Strain Rate:in/min Failure Strain:% Calculated Saturation:% Height:in. Diameter:in. SPECIMEN FAILURE PHOTOGRAPH Remarks: Percent < #200 SievePIPLLL 1642 DESCRIPTION: SANDY SILT(ML) 0.0800 Dry Density:pcf Moisture Content:% 6.29 2.00 2.7 Height / Diameter Ratio: Calculated Void Ratio: Undrained Shear Strength:(psf) Unconfined Compressive Strength (psf) 163046 Assumed Specific Gravity: 3284 3.86 1.93 SPECIMEN TEST DATA 18.8 59.9 0 100 200 300 400 500 600 700 800 900 1,000 0 4 8 12 16 AXIAL STRAIN - % UNCONFINED COMPRESSION TEST ASTM D2166 COMPRESSIVESTRESS-psfPROJECT NUMBER: 20215032 SITE: 2908 S Timberline Road Fort Collins, CO PROJECT: Timberline Apartments CLIENT: Tetrad Property Group LLC Fort Collins, CO 1901 Sharp Point Dr Ste C Fort Collins, CO LABORATORYTESTSARENOTVALIDIFSEPARATEDFROMORIGINALREPORT.UNCONFINEDWITHPHOTOS20215032TIMBERLINEAPARTM.GPJTERRACON_DATATEMPLATE.GDT5/4/21SAMPLE LOCATION:4 @ 9 - 10 feetSAMPLE TYPE: CARS 0.60 81.20 105 Strain Rate:in/min Failure Strain:% Calculated Saturation:% Height:in. Diameter:in. SPECIMEN FAILURE PHOTOGRAPH Remarks: Percent < #200 SievePIPLLL 471 DESCRIPTION: SANDY ELASTIC SILT(MH) 0.0800 Dry Density:pcf Moisture Content:% 14.84 1.93 2.7 Height / Diameter Ratio: Calculated Void Ratio: Undrained Shear Strength:(psf) Unconfined Compressive Strength (psf) 212950 Assumed Specific Gravity: 942 3.72 1.93 SPECIMEN TEST DATA 18.0 58.4 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 0 1.0 2.0 3.0 4.0 5.0 6.0 AXIAL STRAIN - % UNCONFINED COMPRESSION TEST ASTM D2166 COMPRESSIVESTRESS-psfPROJECT NUMBER: 20215032 SITE: 2908 S Timberline Road Fort Collins, CO PROJECT: Timberline Apartments CLIENT: Tetrad Property Group LLC Fort Collins, CO 1901 Sharp Point Dr Ste C Fort Collins, CO LABORATORYTESTSARENOTVALIDIFSEPARATEDFROMORIGINALREPORT.UNCONFINEDWITHPHOTOS20215032TIMBERLINEAPARTM.GPJTERRACON_DATATEMPLATE.GDT5/4/21SAMPLE LOCATION:5 @ 29 - 29.4 feetSAMPLE TYPE: CARS 0.58 66.71 106 Strain Rate:in/min Failure Strain:% Calculated Saturation:% Height:in. Diameter:in. SPECIMEN FAILURE PHOTOGRAPH Remarks: Percent < #200 SievePIPLLL 4079 DESCRIPTION: CLAYSTONE 0.0800 Dry Density:pcf Moisture Content:% 4.92 2.02 2.7 Height / Diameter Ratio: Calculated Void Ratio: Undrained Shear Strength:(psf) Unconfined Compressive Strength (psf) 212142 Assumed Specific Gravity: 8158 3.94 1.95 SPECIMEN TEST DATA 14.4 99.6 0 200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000 2,200 2,400 2,600 0 2 4 6 8 AXIAL STRAIN - % UNCONFINED COMPRESSION TEST ASTM D2166 COMPRESSIVESTRESS-psfPROJECT NUMBER: 20215032 SITE: 2908 S Timberline Road Fort Collins, CO PROJECT: Timberline Apartments CLIENT: Tetrad Property Group LLC Fort Collins, CO 1901 Sharp Point Dr Ste C Fort Collins, CO LABORATORYTESTSARENOTVALIDIFSEPARATEDFROMORIGINALREPORT.UNCONFINEDWITHPHOTOS20215032TIMBERLINEAPARTM.GPJTERRACON_DATATEMPLATE.GDT5/4/21SAMPLE LOCATION:7 @ 4 - 5 feetSAMPLE TYPE: CARS 0.52 87.92 111 Strain Rate:in/min Failure Strain:% Calculated Saturation:% Height:in. Diameter:in. SPECIMEN FAILURE PHOTOGRAPH Remarks: Percent < #200 SievePIPLLL 1297 DESCRIPTION: CLAYEY SAND(SC) 0.0800 Dry Density:pcf Moisture Content:% 6.05 2.10 2.7 Height / Diameter Ratio: Calculated Void Ratio: Undrained Shear Strength:(psf) Unconfined Compressive Strength (psf) 181533 Assumed Specific Gravity: 2595 4.03 1.92 SPECIMEN TEST DATA 17.0 48.2 SUPPORTING INFORMATION Contents: General Notes Unified Soil Classification System Description of Rock Properties Note: All attachments are one page unless noted above. Timberline Apartments Fort Collins, CO Terracon Project No. 20215032 2,000 to 4,000 Unconfined Compressive Strength Qu, (psf) less than 500 500 to 1,000 1,000 to 2,000 4,000 to 8,000 > 8,000 Modified California Ring Sampler Standard Penetration Test N (HP) (T) (DCP) UC (PID) (OVA) Standard Penetration Test Resistance (Blows/Ft.) Hand Penetrometer Torvane Dynamic Cone Penetrometer Unconfined Compressive Strength Photo-Ionization Detector Organic Vapor Analyzer SAMPLING WATER LEVEL FIELD TESTS GENERAL NOTES DESCRIPTION OF SYMBOLS AND ABBREVIATIONS Water levels indicated on the soil boring logs are the levels measured in the borehole at the times indicated. Groundwater level variations will occur over time. In low permeability soils, accurate determination of groundwater levels is not possible with short term water level observations. Water Initially Encountered Water Level After a Specified Period of Time Water Level After a Specified Period of Time Cave In Encountered Exploration point locations as shown on the Exploration Plan and as noted on the soil boring logs in the form of Latitude and Longitude are approximate. See Exploration and Testing Procedures in the report for the methods used to locate the exploration points for this project. Surface elevation data annotated with +/- indicates that no actual topographical survey was conducted to confirm the surface elevation. Instead, the surface elevation was approximately determined from topographic maps of the area. LOCATION AND ELEVATION NOTES Soil classification as noted on the soil boring logs is based Unified Soil Classification System. Where sufficient laboratory data exist to classify the soils consistent with ASTM D2487 "Classification of Soils for Engineering Purposes" this procedure is used. ASTM D2488 "Description and Identification of Soils (Visual-Manual Procedure)" is also used to classify the soils, particularly where insufficient laboratory data exist to classify the soils in accordance with ASTM D2487. In addition to USCS classification, coarse grained soils are classified on the basis of their in-place relative density, and fine-grained soils are classified on the basis of their consistency. See "Strength Terms" table below for details. The ASTM standards noted above are for reference to methodology in general. In some cases, variations to methods are applied as a result of local practice or professional judgment. DESCRIPTIVE SOIL CLASSIFICATION The soil boring logs contained within this document are intended for application to the project as described in this document. Use of these soil boring logs for any other purpose may not be appropriate. RELEVANCE OF SOIL BORING LOG STRENGTH TERMS 30 - 50 > 50 Descriptive Term (Consistency) 8 - 15 > 30 Ring Sampler Blows/Ft. 10 - 29 Medium Hard < 3 2 - 4 BEDROCK Standard Penetration or N-Value Blows/Ft. 0 - 3Very Loose Very Soft (More than 50% retained on No. 200 sieve.) Density determined by Standard Penetration Resistance (50% or more passing the No. 200 sieve.) Consistency determined by laboratory shear strength testing, field visual-manual procedures or standard penetration resistance RELATIVE DENSITY OF COARSE-GRAINED SOILS 30 - 49 50 - 79 _ 6 - 10 11 - 18 19 - 36 > 36 >79 Descriptive Term (Consistency) Firm < 20 Weathered Hard 15 - 30 Standard Penetration or N-Value Blows/Ft. 0 - 1 4 - 8 Very Hard Ring Sampler Blows/Ft. Ring Sampler Blows/Ft. Soft Medium Stiff Stiff Very Stiff Hard CONSISTENCY OF FINE-GRAINED SOILS Standard Penetration or N-Value Blows/Ft. Loose Medium Dense Dense Very Dense < 24 24 - 35 36 - 60 61 - 96 > 96 Descriptive Term (Density) 4 - 9 20 - 29 0 - 5 6 - 14 15 - 46 47 - 79 > 80 3 - 5 UNIFIED SOIL CLASSIFICATION SYSTEM UNIFIED SOI L CLASSI FICATI ON SYSTEM Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A Soil Classification Group Symbol Group Name B Coarse-Grained Soils: More than 50% retained on No. 200 sieve Gravels: More than 50% of coarse fraction retained on No. 4 sieve Clean Gravels: Less than 5% fines C Cu  4 and 1  Cc  3 E GW Well-graded gravel F Cu  4 and/or [Cc<1 or Cc>3.0] E GP Poorly graded gravel F Gravels with Fines: More than 12% fines C Fines classify as ML or MH GM Silty gravel F, G, H Fines classify as CL or CH GC Clayey gravel F, G, H Sands: 50% or more of coarse fraction passes No. 4 sieve Clean Sands: Less than 5% fines D Cu  6 and 1  Cc  3 E SW Well-graded sand I Cu  6 and/or [Cc<1 or Cc>3.0] E SP Poorly graded sand I Sands with Fines: More than 12% fines D Fines classify as ML or MH SM Silty sand G, H, I Fines classify as CL or CH SC Clayey sand G, H, I Fine-Grained Soils: 50% or more passes the No. 200 sieve Silts and Clays: Liquid limit less than 50 Inorganic: PI  7 and plots on or above “A” line J CL Lean clay K, L, M PI  4 or plots below “A” line J ML Silt K, L, M Organic: Liquid limit - oven dried  0.75 OL Organic clay K, L, M, N Liquid limit - not dried Organic silt K, L, M, O Silts and Clays: Liquid limit 50 or more Inorganic: PI plots on or above “A” line CH Fat clay K, L, M PI plots below “A” line MH Elastic Silt K, L, M Organic: Liquid limit - oven dried  0.75 OH Organic clay K, L, M, P Liquid limit - not dried Organic silt K, L, M, Q Highly organic soils: Primarily organic matter, dark in color, and organic odor PT Peat A Based on the mat erial passing the 3-inch (75-mm) sieve. B If field sample contained cobbles or boulders, or both, add “with cobbles or boulders, or both” to group name. C Gravels with 5 to 12% fines require dual symbols: GW -GM well-graded gravel with silt, GW -GC well-graded gravel with clay, GP-GM poorly graded gravel with silt, GP-GC poorly graded gravel with clay. D Sands with 5 to 12% fines require dual symbols: SW -SM well-graded sand with silt, SW -SC well-graded sand with clay, SP-SM poorly graded sand with silt, SP-SC poorly graded sand with clay. E Cu = D60/D10 Cc = 6010 2 30 DxD )(D F If soil contains  15% sand, add “with sand” to group name. G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM. H If fines are organic, add “with organic fines” to group name. I If soil contains  15% gravel, add “with gravel” to group name. J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay. K If soil contains 15 to 29% plus No. 200, add “with sand” or “with gravel,” whichever is predominant. L If soil contains  30% plus No. 200 predominantly sand, add “sandy” to group name. M If soil contains  30% plus No. 200, predominantly gravel, add “gravelly” to group name. N PI  4 and plots on or above “A” line. O PI  4 or plots below “A” line. P PI plots on or above “A” line. Q PI plots below “A” line. DESCRIPTION OF ROCK PROPERTIES ROCK VERSION 1 WEATHERING Term Description Unweathered No visible sign of rock material weathering, perhaps slight discoloration on major discontinuity surfaces. Slightly weathered Discoloration indicates weathering of rock material and discontinuity surfaces. All the rock material may be discolored by weathering and may be somewhat weaker externally than in its fresh condition. Moderately weathered Less than half of the rock material is decomposed and/or disintegrated to a soil. Fresh or discolored rock is present either as a continuous framework or as corestones. Highly weathered More than half of the rock material is decomposed and/or disintegrated to a soil. Fresh or discolored ro ck is present either as a discontinuous framework or as corestones. Completely weathered All rock material is decomposed and/or disintegrated to soil. The original mass structure is still largely intact. Residual soil All rock material is converted to soil. The mass structure and material fabric are destroyed. There is a large change in volume, but the soil has not been significantly transported. STRENGTH OR HARDNESS Description Field Identification Uniaxial Compressive Strength, psi (MPa) Extremely weak Indented by thumbnail 40-150 (0.3-1) Very weak Crumbles under firm blows with point of geological hammer, can be peeled by a pocket knife 150-700 (1-5) Weak rock Can be peeled by a pocket knife with difficulty, shallow indentations made by firm blow with point of geological hammer 700-4,000 (5-30) Medium strong Cannot be scraped or peeled with a pocket knife, specimen can be fractured with single firm blow of geological hammer 4,000-7,000 (30-50) Strong rock Specimen requires more than one blow of geological hammer to fracture it 7,000-15,000 (50-100) Very strong Specimen requires many blows of geological hammer to fracture it 15,000-36,000 (100-250) Extremely strong Specimen can only be chipped with geological hammer >36,000 (>250) DISCONTINUITY DESCRIPTION Fracture Spacing (Joints, Faults, Other Fractures) Bedding Spacing (May Include Foliation or Banding) Description Spacing Description Spacing Extremely close < ¾ in (<19 mm) Laminated < ½ in (<12 mm) Very close ¾ in – 2-1/2 in (19 - 60 mm) Very thin ½ in – 2 in (12 – 50 mm) Close 2-1/2 in – 8 in (60 – 200 mm) Thin 2 in – 1 ft. (50 – 300 mm) Moderate 8 in – 2 ft. (200 – 600 mm) Medium 1 ft. – 3 ft. (300 – 900 mm) Wide 2 ft. – 6 ft. (600 mm – 2.0 m) Thick 3 ft. – 10 ft. (900 mm – 3 m) Very Wide 6 ft. – 20 ft. (2.0 – 6 m) Massive > 10 ft. (3 m) Discontinuity Orientation (Angle): Measure the angle of discontinuity relative to a plane perpendicular to the longitudinal axis of the core. (For most cases, the core axis is vertical; therefore, the plane perpendicular to the core axis is horizontal.) For example, a horizontal bedding plane would have a 0-degree angle. ROCK QUALITY DESIGNATION (RQD) 1 Description RQD Value (%) Very Poor 0 - 25 Poor 25 – 50 Fair 50 – 75 Good 75 – 90 Excellent 90 - 100 1. The combined length of all sound and intact core segments equal to or greater than 4 inches in length, expressed as a percentage of the total core run length. Reference: U.S. Department of Transportation, Federal Highway Administration, Publication No FHWA-NHI-10-034, December 2009 Technical Manual for Design and Construction of Road Tunnels – Civil Elements T r o u t m a nParkPond SpringCreekDr a g o n f l y P o n d Heron PondNew Mercer DitchWa r ren L a k e FossilCreekReservoirInletPle a s ant V alley an d LakeCanalSprin g C reek Larim er CountyCanal#2 S p r i n g C r e e kParkPond W o o d w a r dGoverno rPond P arkwoodLakeP r o s p e c t P o n d #2North Larim er County Canal #2 O a k R i dg eFederalBld gPond H a r m onyReservoir G o l d e nMeadow sPond Canvasback Pond Foothills Channel R o l l a n dMoorePond F t C o l l i n sGolfCoursePond A v e r yPond S pr i n g Creek SherwoodLateral L a k eSherwoodCachela Poudr eRiverCanal #2 New Mercer DitchNew M erce r Ditch B i g P o n d W e s t M i l n eP o n d Larimer County Canal #2O a k R i d g eFederalBld gPond Dixon C anyonLa teralC o n f l u e n c e a n d W i g e o n Po n d s E a s t M i l n e P o n d FOOTHIL LS BASIN K FOO THILLS BASIN APPROXIMATE PROJECT LOCATION FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 3.0 Rational Method 3.4 Intensity-Duration-Frequency Curves for Rational Method Page 8 Table 3.4-1. IDF Table for Rational Method Duration (min) Intensity 2-year (in/hr) Intensity 10-year (in/hr) Intensity 100-year (in/hr) Duration (min) Intensity 2-year (in/hr) Intensity 10-year (in/hr) Intensity 100-year (in/hr) 5 2.85 4.87 9.95 39 1.09 1.86 3.8 6 2.67 4.56 9.31 40 1.07 1.83 3.74 7 2.52 4.31 8.80 41 1.05 1.80 3.68 8 2.40 4.10 8.38 42 1.04 1.77 3.62 9 2.30 3.93 8.03 43 1.02 1.74 3.56 10 2.21 3.78 7.72 44 1.01 1.72 3.51 11 2.13 3.63 7.42 45 0.99 1.69 3.46 12 2.05 3.50 7.16 46 0.98 1.67 3.41 13 1.98 3.39 6.92 47 0.96 1.64 3.36 14 1.92 3.29 6.71 48 0.95 1.62 3.31 15 1.87 3.19 6.52 49 0.94 1.6 3.27 16 1.81 3.08 6.30 50 0.92 1.58 3.23 17 1.75 2.99 6.10 51 0.91 1.56 3.18 18 1.70 2.90 5.92 52 0.9 1.54 3.14 19 1.65 2.82 5.75 53 0.89 1.52 3.10 20 1.61 2.74 5.60 54 0.88 1.50 3.07 21 1.56 2.67 5.46 55 0.87 1.48 3.03 22 1.53 2.61 5.32 56 0.86 1.47 2.99 23 1.49 2.55 5.20 57 0.85 1.45 2.96 24 1.46 2.49 5.09 58 0.84 1.43 2.92 25 1.43 2.44 4.98 59 0.83 1.42 2.89 26 1.4 2.39 4.87 60 0.82 1.4 2.86 27 1.37 2.34 4.78 65 0.78 1.32 2.71 28 1.34 2.29 4.69 70 0.73 1.25 2.59 29 1.32 2.25 4.60 75 0.70 1.19 2.48 30 1.30 2.21 4.52 80 0.66 1.14 2.38 31 1.27 2.16 4.42 85 0.64 1.09 2.29 32 1.24 2.12 4.33 90 0.61 1.05 2.21 33 1.22 2.08 4.24 95 0.58 1.01 2.13 34 1.19 2.04 4.16 100 0.56 0.97 2.06 35 1.17 2.00 4.08 105 0.54 0.94 2.00 36 1.15 1.96 4.01 110 0.52 0.91 1.94 37 1.16 1.93 3.93 115 0.51 0.88 1.88 38 1.11 1.89 3.87 120 0.49 0.86 1.84 FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 3.0 Rational Method 3.4 Intensity-Duration-Frequency Curves for Rational Method Page 9 Figure 3.4-1. Rainfall IDF Curve – Fort Collins This unofficial copy was downloaded on Feb-17-2021 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA This unofficial copy was downloaded on Feb-17-2021 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80524 USA TIMBERLINE ATTAINABLE HOUSING June 2, 2021 APPENDIX E - DRAINAGE PLANS TIMBERLINE CHURCHS TIMBERLINE ROAD IOWA DRIVE ILLINOIS DRIVEFOOTHILLS CHANNELOS2OS1A1A2A3E1B1B2B3B4D1D2C2C1C4C3B5A4OWNER:DATE:SHEET TITLE:OWNER:DATE:SHEET TITLE:CHECKED BY:DRAWN BY: TIMBERLINE HOUSING PROJECT DEVELOPMENT PLAN (PDP) 2908 S TIMBERLINE RD, FORT COLLINS, CO 80525TIMBERLINE CHURCH2908 S TIMBERLINE RD,FORT COLLINS, CO 80525(970) 482-4387T. OGRENB. NEMEC 6/2/2021 SUBMITTAL 8/18/2021 SUBMITTAL244 North College Avenue #130Fort Collins, Colorado 80524P 970.409.3414www.norris-design.comNOT FORCONSTRUCTIONSHEET TITLE:MARTIN/MARTINC O N S U L T I N G E N G I N E E R S12499 WEST COLFAX AVENUELAKEWOOD, COLORADO 80215303.431.6100MARTINMARTIN.COMEXISTING DRAINAGE PLANC10.00EXISTING DRAINAGE PLANXXXXXXXXXXXXXXXX811 S TIMBERLINE ROAD IOWA DRIVE ILLINOIS DRIVEFOOTHILLS CHANNELBUILDING 1FFE=4929.75BUILDING 2FFE=4929.25BUILDING 3FFE=4929.00BUILDING 4FFE=4929.25BUILDING 6FFE=4930.00P1P2P4P7P6P11ABCEGFDGOS2OS1A1B1B2C1C4C3B5A4TIMBERLINE CHURCHBUILDING 5FFE=4929.75FFE=4932.23FFE=4931.57FFE=4932.90OWNER:DATE:SHEET TITLE:OWNER:DATE:SHEET TITLE:CHECKED BY:DRAWN BY: TIMBERLINE HOUSING PROJECT DEVELOPMENT PLAN (PDP) 2908 S TIMBERLINE RD, FORT COLLINS, CO 80525TIMBERLINE CHURCH2908 S TIMBERLINE RD,FORT COLLINS, CO 80525(970) 482-4387T. OGRENB. NEMEC 6/2/2021 SUBMITTAL 8/18/2021 SUBMITTAL244 North College Avenue #130Fort Collins, Colorado 80524P 970.409.3414www.norris-design.comNOT FORCONSTRUCTIONSHEET TITLE:MARTIN/MARTINC O N S U L T I N G E N G I N E E R S12499 WEST COLFAX AVENUELAKEWOOD, COLORADO 80215303.431.6100MARTINMARTIN.COMC11.00PROPOSED DRAINAGE PLAN811XXXXXXXXXXXXXXXX OWNER:DATE:SHEET TITLE:OWNER:DATE:SHEET TITLE:CHECKED BY:DRAWN BY: TIMBERLINE HOUSING PROJECT DEVELOPMENT PLAN (PDP) 2908 S TIMBERLINE RD, FORT COLLINS, CO 80525TIMBERLINE CHURCH2908 S TIMBERLINE RD,FORT COLLINS, CO 80525(970) 482-4387T. OGRENB. NEMEC 6/2/2021 SUBMITTAL 8/18/2021 SUBMITTAL244 North College Avenue #130Fort Collins, Colorado 80524P 970.409.3414www.norris-design.comNOT FORCONSTRUCTIONSHEET TITLE:MARTIN/MARTINC O N S U L T I N G E N G I N E E R S12499 WEST COLFAX AVENUELAKEWOOD, COLORADO 80215303.431.6100MARTINMARTIN.COMXXXXXXP1AP4P5P6GP8P13P14P1P4P5P6P8P13ABCDEFC11.01WATER QUALITY TREATMENTTRAIN