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HomeMy WebLinkAboutSTANFORD SENIOR LIVING - FDP210017 - SUBMITTAL DOCUMENTS - ROUND 5 - DRAINAGE REPORT FINAL DRAINAGE REPORT STANFORD SENIOR LIVING Fort Collins, Colorado October 13, 2021 Prepared for: United Properties 1331 17th Street Denver, CO 80202 Prepared by: 301 North Howes Street, Suite 100 Fort Collins, Colorado 80521 Phone: 970.221.4158 Fax: 970.221.4159 www.northernengineering.com Project Number: 1530-002  This Drainage Report is consciously provided as a PDF. Please consider the environment before printing this document in its entirety. When a hard copy is absolutely necessary, we recommend double-sided printing. October 13, 2021 City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, Colorado 80521 RE: Final Drainage Report for Stanford Senior Living Dear Staff: Northern Engineering is pleased to submit this Final Drainage Report for your review. This report accompanies the Final Development Review submittal for the proposed Stanford Senior Living. This report has been prepared in accordance with the Fort Collins Stormwater Criteria Manual (FCSCM) and Urban Storm Drainage Criteria Manual. This report serves to document the stormwater impacts associated with the proposed Stanford Senior Living project. We understand that review by the City is to assure general compliance with standardized criteria contained in the FCSCM. If you should have any questions as you review this report, please feel free to contact us. Sincerely, NORTHERN ENGINEERING SERVICES, INC. Blaine Mathisen, PE Project Engineer Stanford Senior Living Final Drainage Report TABLE OF CONTENTS I. GENERAL LOCATION AND DESCRIPTION ................................................................... 1 A. Location ............................................................................................................................................. 1 B. Description of Property ..................................................................................................................... 2 C. Floodplain.......................................................................................................................................... 3 II. DRAINAGE BASINS AND SUB-BASINS ....................................................................... 5 A. Major Basin Description .................................................................................................................... 5 B. Sub-Basin Description ....................................................................................................................... 5 III. DRAINAGE DESIGN CRITERIA ................................................................................... 6 A. Regulations........................................................................................................................................ 6 B. Four Step Process .............................................................................................................................. 6 C. Development Criteria Reference and Constraints ............................................................................ 7 D. Hydrological Criteria ......................................................................................................................... 7 E. Hydraulic Criteria .............................................................................................................................. 7 F. Floodplain Regulations Compliance .................................................................................................. 8 G. Modifications of Criteria ................................................................................................................... 8 IV. DRAINAGE FACILITY DESIGN .................................................................................... 8 A. General Concept ............................................................................................................................... 8 B. Specific Details ................................................................................................................................ 10 V. CONCLUSIONS ...................................................................................................... 11 A. Compliance with Standards ............................................................................................................ 11 B. Drainage Concept ............................................................................................................................ 12 References ....................................................................................................................... 13 APPENDICES: APPENDIX A – Hydrologic Computations APPENDIX B – Hydraulic Computations B.1 – Storm Sewers B.2 – Inlets B.3 – Detention Facilities APPENDIX C – Water Quality Design Computations APPENDIX D – Erosion Control Report APPENDIX E – Additional References Stanford Senior Living Final Drainage Report LIST OF TABLES AND FIGURES: Figure 1 - Vicinity Map ........................................................................................................ 1 Figure 2 – Aerial Photograph ................................................................................................ 3 Figure 3 – Existing FEMA Floodplains .................................................................................... 4 Figure 4 – Existing City Floodplains ....................................................................................... 4 Table 1 - Pond Summary ................................................................................................... 11 Table 2 - Chamber Count Summary ..................................................................................... 11 MAP POCKET: Existing Drainage Exhibit DR1 - Drainage Exhibit Stanford Senior Living Final Drainage Report 1 I. GENERAL LOCATION AND DESCRIPTION A. Location 1. Vicinity Map Figure 1 - Vicinity Map 2. Stanford Senior Living project is located in the southwest quarter of Section 25, Township 7 North, Range 69 West of the 6th Principal Meridian, City of Fort Collins, County of Larimer, State of Colorado. 3. The project site is located at the southwest corner of the Stanford Road and Monroe Drive intersection. 4. Currently the site is vacant on the north side of the lot with native grasses and patches of gravel. The south half of the project site is currently an asphalt parking lot with landscaped medians that the Marriot Hotel is currently utilizing for guest parking. The undeveloped portion of the site drains via overland flow at an average grade of 3.50% to the south towards the existing parking lot. In general, the site conveys stormwater runoff from the north to the south where it is collected by a customized inlet in the southeast corner of the existing parking lot. 5. In the existing condition most of the site is being captured by a custom inlet in the southeast corner of the parking lot that was designed per Strachan Subdivision 3rd Filing. A small portion of the existing drive entrance aisle is being conveyed via curb and gutter to existing inlets at the northwest corner of the Stanford Road and Horsetooth Road intersection. Both the custom inlet in the parking lot and inlets at Stanford Senior Living Final Drainage Report 2 the intersection tie into existing 30”x36” HERCP pipes. From there the runoff is routed via the HERCP pipes into Warren Lake which is located at the southeast corner of the Stanford Road and Horsetooth Road intersection. 6. “Stanford Senior Living is in the Foothills Drainage Basin Master Plan that was prepared by Resource Consultants, Inc. and dated July 1980. The Strachan Subdivision Third Filing was developed in 1980 and was divided into two basins. The Southerly Basin, which contains 17.9 acres and drains to the corner of Horsetooth Road and Stanford Road. Mitchell and Co. were the developers, and they paid the Warren Lake Company for storm water detention rights in Warren Lake for Strachan Subdivision 1st, 2nd, and 3rd Filings. These filings correspond to the area between Monroe Drive and Horsetooth Road and between College Avenue and Stanford Road. They also developed the Strachan Continental Subdivision at the southwest corner of Horsetooth Road and J.F.K Parkway. Its detention was also paid for in Warren Lake.” – Final Drainage Report for J.F.K. Office P.U.D 7. According to the Final Drainage Report for J.F.K. Office P.U.D the HERCP pipes in the southeast corner of the parking lot were sized to carry the 10-year event (48 cfs) for the Strachan Subdivision while the 100-year event overtopped Horsetooth Road and sheet flowed to Warren Lake. Due to the report being 40 years old it is important that the Stanford Senior Living project does not adversely impact downstream infrastructure but is still allowed to utilize the Warren Lake Company agreement to some degree. Therefore, the Stanford Senior Living project will detain the difference between the historic 10-year runoff and the proposed 100-year runoff. By utilizing this approach, the Stanford Senior Living center will be reducing the historic flows to the existing inlet at the corner of the parking lot. Additionally, the downstream infrastructure will not be adversely impacted, and the Stanford Senior Living center will no longer contribute to the 100-year flows that currently overtop Horsetooth Road during the major event. B. Description of Property 1. The Stanford Senior Living project has a total acreage of 3.79 acres. However, the Stanford Senior Living project only plans on developing 2.50 acres and leaving the existing parking lot in place. The existing parking lot (1.29 acres) historically sheet flows to the southeast to the custom inlet box as previously described. Therefore, Stanford Senior Living will only be detaining and treating 2.50 acres. The proposed flows to the existing inlet will be reduced because the Stanford Senior Living Center is detaining the difference between the 10-year historic and 100-year developed. The 10-year historic rate is also a conservative release because it assumed that there is no pervious area currently on the 2.50 acres that is proposed with this development. However, that is not the case as there is existing hardscape on the property. These areas include a drive aisle and some gravel roads that are currently being undetained and untreated. Please refer to Appendix A for the runoff calculations. Stanford Senior Living Final Drainage Report 3 Figure 2 – Aerial Photograph 2. The Stanford Senior Living project will consist of a new assisted living and memory care center. It will be a four-story building with underground parking. There is an existing parking lot that is currently being used by the Marriot Hotel for overflow guest parking which will now serve as the Stanford Senior Living parking lot. 3. According to the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Soil Survey, 100 percent of the site consists of Nunn clay loam, which fails into Hydrologic Soil Group C 4. No irrigation facilities or major drainageways are within the property limits. 5. The project site is within a General Commercial District (C-G) Zoning District. The proposed use is permitted within the zone district. C. Floodplain 1. The subject property is not located in a FEMA or City regulatory floodplain. 2. The FEMA Panel 08069C0987G illustrates that this project site is not near any FEMA delineated regulatory floodplain. Stanford Senior Living Final Drainage Report 4 Figure 3 – Existing FEMA Floodplains Figure 4 – Existing City Floodplains Stanford Senior Living Final Drainage Report 5 II. DRAINAGE BASINS AND SUB-BASINS A. Major Basin Description 1. The Stanford Senior Living project is in the Foothills Basin which is centrally located in Fort Collins. The basin is mostly developed with commercial development along College Avenue and mixed-use residential in the remainder of the basin. The basin drains from west to east through open channels or a storm sewer system to the Fossil Creek Reservoir. B. Sub-Basin Description 1. The property historically drains from the northwest to the southeast corner of the existing parking lot via overland flow. The existing parking lot was developed as a part of the Strachan Subdivision 3rd Filing and is currently being used by the Marriot Hotel and Merrill Lynch Wealth Management. As previously described, there is a custom inlet in the southeast corner of the parking lot that has three 30”x36” HERCP that currently routes the 10-year storm event east across Stanford Road to a junction box that then routes the runoff south across Horsetooth Road where it is ultimately discharged into Warren Lake. The 100-year event has historically overtopped Horsetooth Road and overland flowed south to Warren Lake. There are two on-grade inlets at the northwest corner of the intersection of Horsetooth Road and Stanford Road that collects additional flows. These additional flows are then routed to the existing 30”x36” HERCP pipes crossing Stanford Road. 2. A historic rational calculation was performed for the 2.50 acres that will be getting disturbed during the construction of the Stanford Senior Living project. According the FCSCM Chapter 6 developments are only responsible for detaining any newly installed impervious areas. Since the parking lot is existing, and downstream of the new development, the Stanford Senior Living project will not be detaining or treating any runoff that has historically drained to the custom inlet at the southeast corner of the parking lot. Additionally, the Stanford Senior Living project is maintaining the existing drainage patterns within Stanford Road and Monroe Drive. Therefore, no runoff generated on the adjacent streets will be routed through the proposed detention and water quality facility. 3. Following FCSCM requirements for rational calculations the 10-year runoff generated by the existing 2.50 acres is 2.23 cfs. Therefore, Stanford Senior Living can have a max release rate of 2.23 cfs. Traditionally, Fort Collins requires the 2-year event dictate the max release rate but since there is a historic agreement in place with Warren Lake Company to detain all runoff from Strachan Subdivision Third Filing this new development can release at a higher release rate than current FCSCM requirements. By releasing at the historic 10-year event it ensures that downstream infrastructure is not adversely impacted while also allowing the developers to use their agreement with Warren Lake Company to some extent. See Section IV.A.4 below for a more detailed description of the project’s proposed drainage patterns. 4. No offsite drainage is being routed through the property. 5. Please refer to the Appendix for additional information about the existing conditions. Stanford Senior Living Final Drainage Report 6 III. DRAINAGE DESIGN CRITERIA A. Regulations There are optional provisions outside of the FCSCM proposed with the Stanford Senior Living project. Stanford Senior Living project will be detaining the difference between the historic 10-year event and proposed 100-year event. This deviates from the standard historic 2-year and proposed 100-year difference for detention requirements set forth in the FCSCM. B. Four Step Process The overall stormwater management strategy employed with Stanford Senior Living project utilizes the “Four Step Process” to minimize adverse impacts of urbanization on receiving waters. The following is a description of how the proposed development has incorporated each step. Step 1 – Employ Runoff Reduction Practices Several techniques have been utilized with the proposed development to facilitate the reduction of runoff peaks, volumes, and pollutant loads as the site is developed from the current use by implementing multiple Low-Impact Development (LID) strategies including: Providing vegetated open areas along the north, south, east and west portion of the site to reduce the overall impervious area and to minimize directly connected impervious areas (MDCIA). Routing runoff through the drain rock within the underground detention facility to increase time of concentration, promote infiltration, and provides water quality via the isolator rows. Step 2 – Implement BMPs That Provide a Water Quality Capture Volume (WQCV) with Slow Release The efforts taken in Step 1 will facilitate the reduction of runoff and provide the necessary BMPs required for water quality. All runoff that is captured on site will be routed through isolator rows within Stormtech chambers. The isolator rows will remove sediment and other pollutants through filtration. Step 3 – Stabilize Drainageways As stated in Section I.B.4, above, there are no major drainageways in or near the subject site. While this step may not seem applicable to Stanford Senior Living, the proposed project indirectly helps achieve stabilized drainageways nonetheless. Once again, site selection has a positive effect on stream stabilization. By detaining the difference between the 10-year and 100-year events there will be less stress on the downstream infrastructure. Combining detention with LID reduces the likelihood of bed and bank erosion within Warren Lake. Furthermore, this project will pay one-time stormwater development fees, as well as ongoing monthly stormwater utility fees, both of which help achieve citywide drainageway stability. Step 4 – Implement Site Specific and Other Source Control BMPs. This step typically applies to industrial and commercial developments and is not necessarily applicable for this project. However, a localized trash collection system that is stored externally to the building and in a sump condition will reduce the potential impacts of garbage making its way downstream. Stanford Senior Living Final Drainage Report 7 C. Development Criteria Reference and Constraints 1. There are existing drainage studies for this area. They were completed as part of the Strachan Continental Subdivision as well as the J.F.K Office P.U.D. These reports can be found in the Appendix and serve as the basis for the 10-year release rate. Only the pertinent information was pulled from these reports and highlighted. For the complete reports please refer to the Fort Collins erecords website. 2. The subject property is an "in-fill" development project as the property is surrounded by currently developed properties. As such, several constraints have been identified during this analysis that will impact the proposed drainage system including: Existing elevations along the northern and eastern right-of-ways make it difficult to capture all the flow along these edges. However, it should be noted that the areas that are freely discharging to either Monroe Drive or Stanford Road are associated with the vegetated parkways. Therefore, runoff impacts are minor, and it still maintains the historic conveyance path for these areas. As previously mentioned, overall drainage patterns within the Master Drainage Plan for Strachan Continental Subdivision will be maintained. The conveyance path that runoff is using is the same as it historically has been. There are issues with the Strachan Continental master plan as it is no longer compliant with Fort Collins codes and standards. However, at the time of this report there are no known issues with this existing master drainage plan. The city has not identified the intersection of Horsetooth Road and Stanford Road as a problem intersection and there are currently no future plans to revitalize this intersection. However, the Stanford Senior Living Center is proposing detaining and treating 2.50 acres of runoff in order to help alleviate some of the downstream infrastructure. For additional information on detention and water quality please see Section IV.B of this report. D. Hydrological Criteria 1. The City of Fort Collins Rainfall Intensity-Duration-Frequency Curves, as depicted in Figure RA-16 of the FCSCM, serve as the source for all hydrologic computations associated with this development. Tabulated data contained in Table RA-7 has been utilized for Rational Method runoff calculations. 2. The Rational Method has been employed to compute stormwater runoff utilizing coefficients contained in Tables RO-11 and RO-12 of the FCSCM. 3. The Rational Formula-based Modified Federal Aviation Administration (FAA) procedure has been utilized for detention storage calculations. 4. Three separate design storms have been utilized to address distinct drainage scenarios. The first event analyzed is the “Minor,” or “Initial” Storm, which has a 2- year recurrence interval. The second event considered is the “Major Storm,” which has a 100-year recurrence interval. The third storm computed, for detention requirements, is the 10-year recurrence interval. 5. No other assumptions or calculation methods have been used with this development that are not referenced by current City of Fort Collins criteria. E. Hydraulic Criteria 1. As previously noted, the subject property historically drains to the custom inlet at the southeast corner of the existing parking lot. From there, the runoff is routed via a Stanford Senior Living Final Drainage Report 8 series of elliptical pipes to Warren Lake where it has been historically detained and treated for water quality. 2. All drainage facilities proposed with the Stanford Senior Living project are designed in accordance with criteria outlined in the FCSCM and/or the Mile High Flood Control District’s Urban Storm Drainage Criteria Manual. 3. As stated in Section I.C.1, above, the subject property is not located within any regulatory floodplain. 4. Stanford Senior Living project does not propose to modify any natural drainageways. F. Floodplain Regulations Compliance 1. As previously mentioned, all structures are located outside of any FEMA 100-year or City floodplain, and thus are not subject to any floodplain regulations. G. Modifications of Criteria 1. The proposed Stanford Senior Living development is requesting a modification at this time. As previously stated, the original Strachan Thrid Filing included this area as part of the agreement with Warren Lake Company to detain and provide water quality treatment for developed stormwater runoff. However, to meet current FCSCM requirements Stanford Senior Living can no longer allow the 100-year event to overtop Horsetooth Road. Therefore, to meet current FCSCM criteria while also utilizing the Warren Lake agreement to the fullest extent possible Stanford Senior Living will be detaining the difference between the historic 10-year event and proposed 100-year event. IV. DRAINAGE FACILITY DESIGN A. General Concept 1. The main objectives of Stanford Senior Living drainage design are to improve the surrounding stormwater infrastructure while also maintaining historic drainage patterns. 2. As previously mentioned, there are no off-site flows draining onto the existing property. 3. A list of tables and figures used within this report can be found in the Table of Contents at the front of the document. The tables and figures are located within the sections to which the content best applies. 4. The Stanford Senior Living project is composed of nine major drainage basins, designated as Basins A, B, C, D, E, F, G, H, and OS. The drainage patterns for each major basin are further described below. Basin H has 12 minor drainage basins associated with the breakdown of the roofline. Basin A Basin A represents the area in the northwest corner of the site. It consists of a small portion of concrete walk and patio but most of the area is landscaping. Runoff from this basin will enter the storm sewer and be conveyed to the Stormtech chambers. Stanford Senior Living Final Drainage Report 9 Basin B Basin B encompasses a small area near the trash enclosure. Runoff generated in Basin B will enter the storm sewer system via an area inlet and be conveyed to the Stormtech chambers. Basin C Basin C is associated with the memory care garden near the northeast corner of the site. Runoff in Basin C will be collected via area inlets and be routed via storm sewer to the Stormtech chambers. Basin D Basin D consists of a small amount of concrete walk and the rest being landscaping with a swale conveying stormwater runoff to an area drain near the drive entrance of the site. Runoff from Basin D will be conveyed to the Stormtech chambers via a storm sewer. Basin E Basin E is associated with the area in front of the building. This area consists of concrete walks, asphalt drive aisles, and landscaped islands. Runoff from Basin E is collected via a series of area drains. Once runoff is collected in the area drains the runoff is routed to the Stormtech chambers via the storm sewer. Basin F Basin F is associated with the drive entrance that will flow east and be captured by an on-grade inlet. Runoff will then be routed to the Stormtech chambers via the storm sewer. Basin G Basin G is a swath of land along southwest boundary near the Marriot Hotel. Runoff generated in Basin G will flow along the property line in a landscape swale and then be routed to an area inlet that is located at the entrance to the garage. From there the runoff will be conveyed via the storm sewer to the Stormtech chambers. Basin H (Basins H1-H12) Basin H encompasses the entire building and consists of 12 minor basins. Runoff from Basins H1-H11 will be collected in roof leaders and conveyed to the Stormtech chambers via the storm sewer. There is also an internal courtyard (Basin H12) in the center of the building which will generate a small amount of runoff. Runoff from the courtyard will be collected by area drains which will then be conveyed via storm sewer that runs through the building and connects to the external storm sewer that runs adjacent to the building. All runoff from Basin H will be routed to the Stormtech chambers. Stanford Senior Living Final Drainage Report 10 Basin OS Basin OS is a small amount of landscaping and concrete area that cannot be captured on site because of topographic constraints. Runoff from Basin OS (0.48 cfs) sheet flows north offsite to Monroe Drive where it then flows east towards Stanford Road. Once in Stanford Road it flows south to the inlet at the northwest corner of the Horsetooth Road and Stanford Road intersection. Because Basin OS is releasing undetained, the Stanford Senior Living project will include the undetained flow as part of the allowable release rate, and thus will throttle the release from the Stormtech chambers. By reducing the overall release rate by the undetained flows from Basin OS (0.48 cfs), that ensures that Stanford Senior Living is in fact releasing no more than the historic 10-yr release rate of 2.23 cfs and all downstream infrastructure is not adversely impacted. A full-size copy of the Drainage Exhibit can be found in the Map Pocket at the end of this report. B. Specific Details 1. The release rate for the proposed development was established by calculating the 10- year historic runoff rate of the area proposed for development minus the 100-year developed flow from Basin OS as previously discussed. As mentioned in section III.G this is a modification to the FCSCM. By utilizing a reduced historic 10-year peak runoff the Stanford Senior Living project will maintain downstream infrastructure while also utilizing their agreement with Warren Lake Company to detain this site’s runoff. 2. The Stanford Senior Living project area will no longer be contributing to the spill that overtops Horsetooth Road during the major event because the project is detaining the difference between the historic 10-year and developed 100-year runoff. 3. These release rates were utilized in the FAA method for design of the pond. (Refer to Appendix B for these calculations). 4. Detention Pond Calculations Pond Calculations were completed for the underground pond, based on the proposed land use characteristics of Basins A, B, C, D, E, F, G, and H with a release rate of 1.75 cfs, indicates a detention volume of 19,271 cu. ft. The 1.75 cfs was calculated by taking the historic 10-yr runoff rate of 2.23 cfs and subtracting Basin OS 100-yr runoff rate of 0.48 (2.23-0.48=1.75 cfs). Based on Stormtech specifications in order to achieve 19,271 cu. ft. of detention it will require 103 MC-3500 chambers. However, based on the Stormtech system layout Stanford Senior Living will be providing 20,002 cu. ft. of detention. 5. Water Quality Pond Calculations Pond The Stanford Senior Living project will be providing 100% of their water quality capture volume in the form of isolator rows within the Stormtech system. Isolator rows qualify as a BMP measure and therefore 100% of the water quality capture volume will be provided in the form of low impact development (LID). Isolator rows Stanford Senior Living Final Drainage Report 11 are designed to retain sediment and filter out the first flush of any storm event. At the end of each isolator row is a Nyloplast Basin that allows for routine and easy maintenance so that the entire system can be maintained for its design life. Basin OS (0.15 acres) cannot be captured but water quality is still be provided for in Warren Lake per the offsite detention/water quality agreement with the Warren Lake Company, as it historically has been. Following FCSCM requirements yields a WQCV of 2,272 cu. ft. Utilizing available chamber sizing and infiltration data provided by Stormtech requires 18 additional MC-3500 chambers to meet the required WQCV. 6. Pond Summary Pond The Stanford Senior Living project will be utilizing 121 MC-3500 Stormtech chambers to fulfill their stormwater detention and treatment requirements. Stanford Senior Living will be providing 100% WQCV using LID measures. Required Detention (cu. ft.) Provided Detention (cu. ft.) Required WQCV (cu. ft.) Provided WQCV (cu. ft.) Required Total Volume (cu. ft.) Provided Volume (cu. ft.) 19,271 20,002 2,272 2,275 21,543 22,277 Table 1 - Pond Summary MC-3500 Chamber Counts Detention WQCV Total 103 18 121 Table 2 - Chamber Count Summary V. CONCLUSIONS A. Compliance with Standards 1. The drainage design proposed with Stanford Senior Living project complies with the City of Fort Collins’ Stormwater Criteria Manual. 2. The drainage design proposed with Stanford Senior Living project complies with the City of Fort Collins’ Master Drainage Plan for the Foothills Basin. 3. The drainage design proposed with Stanford Senior Living project complies with the Master Drainage Plan for Strachan Continental Subdivision. 4. There are no regulatory floodplains associated with the Stanford Senior Living development. 5. The drainage plan and stormwater management measures proposed with the Stanford Senior Living development are compliant with all applicable State and Federal regulations governing stormwater discharge. Stanford Senior Living Final Drainage Report 12 B. Drainage Concept 1. The drainage design proposed with this project will effectively limit potential damage associated with its stormwater runoff. The drainage design proposed with this project will be utilizing the agreement with the Warren Lake Company to some extent. 2. The Stanford Senior Living project will detain the difference between the historic 10- year event and the developed 100-year event. 3. The Stanford Senior Living project will be providing 100% WQCV using an LID measure. Stanford Senior Living Final Drainage Report 13 References 1. City of Fort Collins Landscape Design Guidelines for Stormwater and Detention Facilities, November 5, 2009, BHA Design, Inc. with City of Fort Collins Utility Services. 2. Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, as adopted by Ordinance No. 159, 2018, and referenced in Section 26-500 (c) of the City of Fort Collins Municipal Code. 3. Larimer County Urban Area Street Standards, Adopted January 2, 2001, Repealed and Reenacted, Effective October 1, 2002, Repealed and Reenacted, Effective April 1, 2007. 4. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation Service, United States Department of Agriculture. 5. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control District, Wright-McLaughlin Engineers, Denver, Colorado, Revised April 2008. 6. Final Drainage Report For J.F.K Office P.U.D, January 9, 1995, Vaught-Frye Architects 7. Strachan Continental Subdivision Storm Drainage Report, July 3, 1981, James H. Stewart & Associates, INC APPENDIX A HYDROLOGIC COMPUTATIONS CHARACTER OF SURFACE1: Percentage Impervious 2-yr Runoff Coefficient 10-yr Runoff Coefficient 100-yr Runoff Coefficient Developed Asphalt .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………100%0.95 0.95 1.00 Concrete .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………100%0.95 0.95 1.00 Rooftop .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………90%0.95 0.95 1.00 Gravel .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………40%0.50 0.50 0.63 Pavers .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………40%0.50 0.50 0.63 Landscape or Pervious Surface Playgrounds .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………25%0.35 0.35 0.44 Lawns Clayey Soil .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………2%0.25 0.25 0.31 Lawns Sandy Soil .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………2%0.15 0.15 0.19 Notes: Basin ID Basin Area (ac) Area of Asphalt (ac) Area of Concrete (ac) Area of Rooftop (ac) Area of Gravel (ac) Area of Pavers (ac) Area of Playgrounds (ac) Area of Lawns (ac) Composite % Imperv. 2-year Composite Runoff Coefficient 10-year Composite Runoff Coefficient 100-year Composite Runoff Coefficient H 2.50 0.00 0.00 0.00 0.00 0.00 0.00 2.50 2%25%25%31% HISTORIC BASIN % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS 2) Runoff Coefficients are taken from the Fort Collins Stormwater Criteria Manual, Chapter 3. Table 3.2-1 and 3.2-2 1) Percentage impervious taken from the Fort Collins Stormwater Criteria Manual, Chapter 5, Table 4.1-2 and Table 4.1-3 Overland Flow, Time of Concentration: Channelized Flow, Time of Concentration: Total Time of Concentration : T c is the lesser of the values of Tc calculated using T c = T i + T t C2 C100 Length, L (ft) Slope, S (%) Ti2 Ti100 Length, L (ft) Slope, S (%) Roughness Coefficient Assumed Hydraulic Radius Velocity, V (ft/s) Tt (min)Tc (Eq. 3.3-5) Tc2 = Ti +Tt Tc100 = Ti +Tt Tc2 Tc100 h H 0.25 0.31 310 2.75%20.0 18.6 0 N/A N/A N/A N/A N/A 11.7 20.0 18.6 11.7 11.7 HISTORIC TIME OF CONCENTRATION Channelized Flow Design Point Basin Overland Flow Time of Concentration Frequency Adjustment Factor: (Equation 3.3-2 FCSCM) (Equation 5-5 FCSCM) (Equation 5-4 FCSCM) (Equation 3.3-5 FCSCM) Table 3.2-3 FCSCM Therefore Tc2=Tc10 Rational Method Equation: Rainfall Intensity: h H 2.50 11.7 11.7 0.25 0.31 2.09 3.57 7.29 1.31 2.23 5.65 Tc100 (min) Intensity, i2 (in/hr) Intensity, i100 (in/hr) HISTORIC RUNOFF COMPUTATIONS Design Point Basin(s)Area, A (acres) Tc2 (min) Flow, Q2 (cfs) Flow, Q100 (cfs) C2 C100 IDF Table for Rational Method - Table 3.4-1 FCSCM Intensity, i10 (in/hr) Flow, Q10 (cfs) AiCCQf BASIN TOTAL AREA (acres) Tc2 (min) Tc100 (min) C2 C100 Q2 (cfs) Q10 (cfs) Q100 (cfs) H 2.50 11.7 11.7 0.25 0.31 1.31 2.23 5.65 Rational Flow Summary | Historic Basin Flow Rates 6/8/202110:28 AM P:\1530-002\Drainage\Hydrology\1530-002_Historical Rational Calcs (FCSCM).xlsx\Summary Tables CHARACTER OF SURFACE1: Percentage Impervious 2-yr Runoff Coefficient 10-yr Runoff Coefficient 100-yr Runoff Coefficient Developed Asphalt .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………100%0.95 0.95 1.00 Concrete .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………100%0.95 0.95 1.00 Rooftop .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………90%0.95 0.95 1.00 Gravel .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………40%0.50 0.50 0.63 Pavers .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………40%0.50 0.50 0.63 Landscape or Pervious Surface Playgrounds .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………25%0.35 0.35 0.44 Lawns Clayey Soil .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………2%0.25 0.25 0.31 Lawns Sandy Soil .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………2%0.15 0.15 0.19 Notes: Basin ID Basin Area (ac) Area of Asphalt (ac) Area of Concrete (ac) Area of Rooftop (ac) Area of Gravel (ac) Area of Pavers (ac) Area of Playgrounds (ac) Area of Lawns (ac) Composite % Imperv. 2-year Composite Runoff Coefficient 10-year Composite Runoff Coefficient 100-year Composite Runoff Coefficient A 0.12 0.00 0.02 0.00 0.00 0.00 0.00 0.11 17% 0.36 0.36 0.42 B 0.05 0.00 0.04 0.00 0.00 0.00 0.00 0.01 82% 0.82 0.82 0.87 C 0.09 0.00 0.09 0.00 0.00 0.00 0.00 0.00 100% 0.95 0.95 1.00 D 0.41 0.00 0.07 0.00 0.00 0.00 0.00 0.34 19% 0.37 0.37 0.43 E 0.27 0.21 0.02 0.00 0.00 0.00 0.00 0.05 84% 0.83 0.83 0.88 F 0.05 0.03 0.01 0.00 0.00 0.00 0.00 0.01 79% 0.80 0.80 0.85 G 0.19 0.03 0.02 0.00 0.00 0.00 0.00 0.15 26% 0.42 0.42 0.48 H1 0.05 0.00 0.00 0.05 0.00 0.00 0.00 0.00 90% 0.95 0.95 1.00 H2 0.11 0.00 0.00 0.11 0.00 0.00 0.00 0.00 90% 0.95 0.95 1.00 H3 0.05 0.00 0.00 0.05 0.00 0.00 0.00 0.00 90% 0.95 0.95 1.00 H4 0.11 0.00 0.00 0.11 0.00 0.00 0.00 0.00 90% 0.95 0.95 1.00 H5 0.05 0.00 0.00 0.05 0.00 0.00 0.00 0.00 90% 0.95 0.95 1.00 H6 0.04 0.00 0.00 0.04 0.00 0.00 0.00 0.00 90% 0.95 0.95 1.00 H7 0.04 0.00 0.00 0.04 0.00 0.00 0.00 0.00 90% 0.95 0.95 1.00 H8 0.06 0.00 0.00 0.06 0.00 0.00 0.00 0.00 90% 0.95 0.95 1.00 H9 0.19 0.00 0.00 0.19 0.00 0.00 0.00 0.00 90% 0.95 0.95 1.00 H10 0.19 0.00 0.00 0.19 0.00 0.00 0.00 0.00 90% 0.95 0.95 1.00 H11 0.09 0.00 0.00 0.09 0.00 0.00 0.00 0.00 90% 0.95 0.95 1.00 H12 0.16 0.00 0.15 0.00 0.00 0.00 0.00 0.02 90% 0.88 0.88 0.93 OS 0.15 0.00 0.00 0.00 0.00 0.00 0.00 0.14 5% 0.27 0.27 0.33 Basins A-OS 2.50 0.27 0.42 0.99 0.00 0.00 0.00 0.82 64% 0.72 0.72 0.77 DEVELOPED BASIN % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS 2) Runoff Coefficients are taken from the Fort Collins Stormwater Criteria Manual, Chapter 3. Table 3.2-1 and 3.2-2 1) Percentage impervious taken from the Fort Collins Stormwater Criteria Manual, Chapter 5, Table 4.1-2 and Table 4.1-3 Combined Basins Overland Flow, Time of Concentration: Channelized Flow, Time of Concentration: Total Time of Concentration : T c is the lesser of the values of Tc calculated using T c = T i + T t C2 C100 Length, L (ft) Slope, S (%) Ti2 Ti100 Length, L (ft) Slope, S (%) Roughness Coefficient Assumed Hydraulic Radius Velocity, V (ft/s) Tt (min)Tc (Eq. 3.3-5) Tc2 = Ti +Tt Tc100 = Ti +Tt Tc2 Tc100 a A 0.36 0.42 50 11.00%4.4 4.0 0 N/A N/A N/A N/A N/A 10.3 4.4 4.0 5.0 5.0 b B 0.82 0.87 25 5.20%1.5 1.2 0 N/A N/A N/A N/A N/A 10.1 1.5 1.2 5.0 5.0 c C 0.95 1.00 30 4.00%1.0 0.6 0 N/A N/A N/A N/A N/A 10.2 1.0 0.6 5.0 5.0 d D 0.37 0.43 20 15.00%2.5 2.3 260 2.23%0.025 0.45 5.23 0.8 11.6 3.3 3.1 5.0 5.0 e E 0.83 0.88 37 4.76%1.8 1.5 19 0.50%0.013 0.15 2.29 0.1 10.3 2.0 1.6 5.0 5.0 f F 0.80 0.85 25 2.24%2.1 1.8 35 3.43%0.013 0.15 5.99 0.1 10.3 2.2 1.9 5.0 5.0 g G 0.42 0.48 25 12.00%2.8 2.5 75 5.00%0.025 0.45 7.83 0.2 10.6 2.9 2.7 5.0 5.0 h1 H1 0.95 1.00 15 0.67%1.2 0.8 0 N/A N/A N/A N/A N/A 10.1 1.2 0.8 5.0 5.0 h2 H2 0.95 1.00 15 0.67%1.2 0.8 0 N/A N/A N/A N/A N/A 10.1 1.2 0.8 5.0 5.0 h3 H3 0.95 1.00 15 0.67%1.2 0.8 0 N/A N/A N/A N/A N/A 10.1 1.2 0.8 5.0 5.0 h4 H4 0.95 1.00 20 0.67%1.4 1.0 0 N/A N/A N/A N/A N/A 10.1 1.4 1.0 5.0 5.0 h5 H5 0.95 1.00 15 0.67%1.2 0.8 0 N/A N/A N/A N/A N/A 10.1 1.2 0.8 5.0 5.0 h6 H6 0.95 1.00 15 0.67%1.2 0.8 0 N/A N/A N/A N/A N/A 10.1 1.2 0.8 5.0 5.0 h7 H7 0.95 1.00 15 0.67%1.2 0.8 0 N/A N/A N/A N/A N/A 10.1 1.2 0.8 5.0 5.0 h8 H8 0.95 1.00 15 0.67%1.2 0.8 0 N/A N/A N/A N/A N/A 10.1 1.2 0.8 5.0 5.0 h9 H9 0.95 1.00 30 0.67%1.8 1.2 0 N/A N/A N/A N/A N/A 10.2 1.8 1.2 5.0 5.0 h10 H10 0.95 1.00 30 0.67%1.8 1.2 0 N/A N/A N/A N/A N/A 10.2 1.8 1.2 5.0 5.0 h11 H11 0.95 1.00 15 0.67%1.2 0.8 0 N/A N/A N/A N/A N/A 10.1 1.2 0.8 5.0 5.0 h12 H12 0.88 0.93 25 0.67%2.3 1.8 0 N/A N/A N/A N/A N/A 10.1 2.3 1.8 5.0 5.0 os OS 0.27 0.33 10 21.00%1.8 1.7 0 N/A N/A N/A N/A N/A 10.1 1.8 1.7 5.0 5.0 Stormtech Basins A-OS 0.72 0.77 20 2.25% 2.4 2.1 15 1.20% 1.30% 15.00% 0.35 0.7 10.2 3.1 2.8 5.0 5.0 Combined Basins DEVELOPED DIRECT TIME OF CONCENTRATION Channelized Flow Design Point Basin Overland Flow Time of Concentration Frequency Adjustment Factor: (Equation 3.3-2 FCSCM) (Equation 5-5 FCSCM) (Equation 5-4 FCSCM) (Equation 3.3-5 FCSCM) Table 3.2-3 FCSCM Therefore Tc2=Tc10 Rational Method Equation: Rainfall Intensity: a A 0.12 5.0 5.0 0.36 0.42 2.85 4.87 9.95 0.13 0.22 0.52 b B 0.05 5.0 5.0 0.82 0.87 2.85 2.85 9.95 0.12 0.12 0.46 c C 0.09 5.0 5.0 0.95 1.00 2.85 2.85 9.95 0.24 0.24 0.90 d D 0.41 5.0 5.0 0.37 0.43 2.85 2.85 9.95 0.43 0.43 1.76 e E 0.27 5.0 5.0 0.83 0.88 2.85 2.85 9.95 0.65 0.65 2.40 f F 0.05 5.0 5.0 0.80 0.85 2.85 2.85 9.95 0.11 0.11 0.43 g G 0.19 5.0 5.0 0.42 0.48 2.85 2.85 9.95 0.23 0.23 0.93 h1 H1 0.05 5.0 5.0 0.95 1.00 2.85 2.85 9.95 0.14 0.14 0.51 h2 H2 0.11 5.0 5.0 0.95 1.00 2.85 2.85 9.95 0.28 0.28 1.05 h3 H3 0.05 5.0 5.0 0.95 1.00 2.85 2.85 9.95 0.13 0.13 0.48 h4 H4 0.11 5.0 5.0 0.95 1.00 2.85 2.85 9.95 0.29 0.29 1.08 h5 H5 0.05 5.0 5.0 0.95 1.00 2.85 2.85 9.95 0.14 0.14 0.50 h6 H6 0.04 5.0 5.0 0.95 1.00 2.85 2.85 9.95 0.12 0.12 0.45 h7 H7 0.04 5.0 5.0 0.95 1.00 2.85 2.85 9.95 0.12 0.12 0.44 h8 H8 0.06 5.0 5.0 0.95 1.00 2.85 2.85 9.95 0.17 0.17 0.61 h9 H9 0.19 5.0 5.0 0.95 1.00 2.85 2.85 9.95 0.53 0.53 1.93 h10 H10 0.19 5.0 5.0 0.95 1.00 2.85 2.85 9.95 0.53 0.53 1.94 h11 H11 0.09 5.0 5.0 0.95 1.00 2.85 2.85 9.95 0.24 0.24 0.87 h12 H12 0.16 5.0 5.0 0.88 0.93 2.85 2.85 9.95 0.41 0.41 1.51 os OS 0.15 5.0 5.0 0.27 0.33 2.85 2.85 9.95 0.11 0.11 0.48 Stormtech Basins A-OS 2.50 5.0 5.0 0.72 0.77 2.85 2.85 9.95 5.13 5.49 19.17 Combined Basins Tc100 (min) Intensity, i2 (in/hr) Intensity, i100 (in/hr) DEVELOPED RUNOFF COMPUTATIONS Design Point Basin(s)Area, A (acres) Tc2 (min) Flow, Q2 (cfs) Flow, Q100 (cfs) C2 C100 IDF Table for Rational Method - Table 3.4-1 FCSCM Intensity, i10 (in/hr) Flow, Q10 (cfs) ()()()AiCCQf= BASIN TOTAL AREA (acres) Tc2 (min) Tc100 (min) C2 C100 Q2 (cfs) Q100 (cfs) A 0.12 5.0 5.0 0.36 0.42 0.13 0.52 B 0.05 5.0 5.0 0.82 0.87 0.12 0.46 C 0.09 5.0 5.0 0.95 1.00 0.24 0.90 D 0.41 5.0 5.0 0.37 0.43 0.43 1.76 E 0.27 5.0 5.0 0.83 0.88 0.65 2.40 F 0.05 5.0 5.0 0.80 0.85 0.11 0.43 G 0.19 5.0 5.0 0.42 0.48 0.23 0.93 H1 0.05 5.0 5.0 0.95 1.00 0.14 0.51 H2 0.11 5.0 5.0 0.95 1.00 0.28 1.05 H3 0.05 5.0 5.0 0.95 1.00 0.13 0.48 H4 0.11 5.0 5.0 0.95 1.00 0.29 1.08 H5 0.05 5.0 5.0 0.95 1.00 0.14 0.50 H6 0.04 5.0 5.0 0.95 1.00 0.12 0.45 H7 0.04 5.0 5.0 0.95 1.00 0.12 0.44 H8 0.06 5.0 5.0 0.95 1.00 0.17 0.61 H9 0.19 5.0 5.0 0.95 1.00 0.53 1.93 H10 0.19 5.0 5.0 0.95 1.00 0.53 1.94 H11 0.09 5.0 5.0 0.95 1.00 0.24 0.87 H12 0.16 5.0 5.0 0.88 0.93 0.41 1.51 OS 0.15 5.0 5.0 0.27 0.33 0.11 0.48 Basins A-OS 2.50 5.0 5.0 0.72 0.77 5.13 19.17 Rational Flow Summary | Developed Basin Flow Rates Combined Basins 5/31/20222:11 PM P:\1530-002\Drainage\Hydrology\1530-002_Proposed Rational Calcs (FCSCM).xlsx\Summary Tables APPENDIX B HYDRAULIC COMPUTATIONS B.1 – Storm Sewers B.2 – Inlets B.3 – Detention Facilities APPENDIX B.1 STORM SEWERS APPENDIX B.2 INLETS Inlet Name:Inlet A4.3 Project: 2-Year Design Flow (cfs)0.22 Location: 100-Year Design Flow (cfs)0.93 Calc. By: Type of Grate: 2.65 Length of Grate (ft):1.97 5,010.80 Width of Grate (ft):1.35 0.50 Depth Above Inlet (ft)Elevation (ft) Shallow Weir Flow (cfs) Orifice Flow (cfs) Actual Flow (cfs)Notes 0.00 5,010.80 0.00 0.00 0.00 0.20 5,011.00 0.89 3.18 0.89 0.40 5,011.20 2.52 4.50 2.52 0.48 5,011.28 3.31 4.93 3.31 Qreq=0.93 (cfs) 0.60 5,011.40 4.63 5.52 4.63 0.80 5,011.60 7.13 6.37 6.37 1.00 5,011.80 9.96 7.12 7.12 1.20 5,012.00 13.09 7.80 7.80 1.40 5,012.20 16.50 8.43 8.43 1.60 5,012.40 20.16 9.01 9.01 1.80 5,012.60 24.05 9.55 9.55 2.00 5,012.80 28.17 10.07 10.07 Depth vs. Flow Fabricated 1530-002 Stanford Senior Living B. Mathisen Reduction Factor: AREA INLET PERFORMANCE CURVE Governing Equations If H > 1.792 (A/P), then the grate operates like an orifice; otherwise it operates like a weir. Input Parameters Rim Elevation (ft): Open Area of Grate (ft2): 0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 0.00 0.50 1.00 1.50 2.00 2.50Discharge (cfs)Stage (ft) Stage - Discharge Curves Series1 Series2 Atlow flow dephs, the inlet will act like a weir governed by the following equation: * where P = 2(L + W) * where H corresponds to the depth of water above the flowline At higher flow depths, the inlet will act like an orifice governed by the following equation: * where A equals the open area of the inlet grate * where H corresponds to the depth of water above the centroid of the cross-sectional area (A). 𝑄= 3.0𝑃𝐻ଵ.ହ 𝑄= 0.67𝐴(2𝑔𝐻)଴.ହ NORTHERNENGINEERING.COM | 970.221.4158 FORT COLLINS | GREELEY Inlet Name:Inlet A4.10 Project: 2-Year Design Flow (cfs)0.12 Location: 100-Year Design Flow (cfs)0.46 Calc. By: Type of Grate: 2.65 Length of Grate (ft):1.97 5,010.80 Width of Grate (ft):1.35 0.50 Depth Above Inlet (ft)Elevation (ft) Shallow Weir Flow (cfs) Orifice Flow (cfs) Actual Flow (cfs)Notes 0.00 5,010.80 0.00 0.00 0.00 0.20 5,011.00 0.89 3.18 0.89 0.40 5,011.20 2.52 4.50 2.52 0.90 5,011.70 8.50 6.76 6.76 Qreq=0.43 (cfs) 0.60 5,011.40 4.63 5.52 4.63 0.80 5,011.60 7.13 6.37 6.37 1.00 5,011.80 9.96 7.12 7.12 1.20 5,012.00 13.09 7.80 7.80 1.40 5,012.20 16.50 8.43 8.43 1.60 5,012.40 20.16 9.01 9.01 1.80 5,012.60 24.05 9.55 9.55 2.00 5,012.80 28.17 10.07 10.07 Input Parameters Fabricated Open Area of Grate (ft 2): Rim Elevation (ft): Reduction Factor: Depth vs. Flow AREA INLET PERFORMANCE CURVE 1530-002 Stanford Senior Living B. Mathisen Governing Equations If H > 1.792 (A/P), then the grate operates like an orifice; otherwise it operates like a weir. 0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 0.00 0.50 1.00 1.50 2.00 2.50Discharge (cfs)Stage (ft) Stage - Discharge Curves Series1 Series2 Atlow flow dephs, the inlet will act like a weir governed by the following equation: * where P = 2(L + W) * where H corresponds to the depth of water above the flowline At higher flow depths, the inlet will act like an orifice governed by the following equation: * where A equals the open area of the inlet grate * where H corresponds to the depth of water above the centroid of the cross-sectional area (A). 𝑄= 3.0𝑃𝐻ଵ.ହ 𝑄= 0.67𝐴(2𝑔𝐻)଴.ହ NORTHERNENGINEERING.COM | 970.221.4158 FORT COLLINS | GREELEY 3130 Verona Avenue • Buford, GA 30518 (866) 888-8479 / (770) 932-2443 • Fax: (770) 932-2490 © Nyloplast Inlet Capacity Charts June 2012 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10Capacity (cfs)Head (ft) Nyloplast 24" Dome Grate Inlet Capacity Chart 3130 Verona Avenue • Buford, GA 30518 (866) 888-8479 / (770) 932-2443 • Fax: (770) 932-2490 © Nyloplast Inlet Capacity Charts June 2012 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10Capacity (cfs)Head (ft) Nyloplast 24" Pedestrian Grate Inlet Capacity Chart 3130 Verona Avenue • Buford, GA 30518 (866) 888-8479 / (770) 932-2443 • Fax: (770) 932-2490 © Nyloplast Inlet Capacity Charts June 2012 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10Capacity (cfs)Head (ft) Nyloplast 18" Pedestrian Grate Inlet Capacity Chart 3130 Verona Avenue • Buford, GA 30518 (866) 888-8479 / (770) 932-2443 • Fax: (770) 932-2490 © Nyloplast Inlet Capacity Charts June 2012 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10Capacity (cfs)Head (ft) Nyloplast 18" Dome Grate Inlet Capacity Chart Version 4.05 Released March 2017 Worksheet Protected INLET NAME INLET A7.1 User-Defined STREET On Grade CDOT Type R Curb Opening USER-DEFINED INPUT User-Defined Design Flows 0.1 0.4 No Bypass Flow Received 0.0 0.0 Watershed Characteristics Watershed Profile Minor Storm Rainfall Input Major Storm Rainfall Input CALCULATED OUTPUT 0.1 0.4 0.0 0.0 Minor Storm (Calculated) Analysis of Flow Time N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Major Storm (Calculated) Analysis of Flow Time N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Overland Length (ft) INLET MANAGEMENT Inlet Application (Street or Area) Hydraulic Condition Minor QKnown (cfs) Major QKnown (cfs) Receive Bypass Flow from: Minor Bypass Flow Received, Qb (cfs) Major Bypass Flow Received, Qb (cfs) Subcatchment Area (acres) Percent Impervious NRCS Soil Type Overland Slope (ft/ft) Inlet Type Bypass (Carry-Over) Flow from Upstream Channel Slope (ft/ft) Channel Length (ft) Design Storm Return Period, Tr (years) One-Hour Precipitation, P1 (inches) Design Storm Return Period, Tr (years) One-Hour Precipitation, P1 (inches) Recommended Tc Tc selected by User Design Rainfall Intensity, I Minor Flow Bypassed Downstream, Qb (cfs) Major Flow Bypassed Downstream, Qb (cfs) Channel Flow Velocity, Vt Overland Flow Time, Ti Channel Travel Time, Tt Calculated Time of Concentration, Tc Regional Tc Minor Total Design Peak Flow, Q (cfs) Major Total Design Peak Flow, Q (cfs) C C5 Overland Flow Velocity, Vi Site Type (Urban or Rural) Calculated Local Peak Flow, Qp Overland Flow Velocity, Vi Channel Flow Velocity, Vt Overland Flow Time, Ti Channel Travel Time, Tt Calculated Time of Concentration, Tc Regional Tc Calculated Local Peak Flow, Qp C Recommended Tc Tc selected by User Design Rainfall Intensity, I C5 Project: Inlet ID: Gutter Geometry (Enter data in the blue cells) Maximum Allowable Width for Spread Behind Curb TBACK =5.0 ft Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =0.020 ft/ft Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.015 Height of Curb at Gutter Flow Line HCURB =6.00 inches Distance from Curb Face to Street Crown TCROWN =15.0 ft Gutter Width W =2.00 ft Street Transverse Slope SX =0.038 ft/ft Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft)SW =0.083 ft/ft Street Longitudinal Slope - Enter 0 for sump condition SO =0.038 ft/ft Manning's Roughness for Street Section (typically between 0.012 and 0.020)nSTREET =0.013 Minor Storm Major Storm Max. Allowable Spread for Minor & Major Storm TMAX =15.0 15.0 ft Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 6.0 inches Allow Flow Depth at Street Crown (leave blank for no) check = yes MINOR STORM Allowable Capacity is based on Depth Criterion Minor Storm Major Storm MAJOR STORM Allowable Capacity is based on Depth Criterion Qallow =13.8 13.8 cfs Minor storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management' Major storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management' Version 4.05 Released March 2017 ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm) (Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread) Stanford Senior Living INLET A7.1 UD-Inlet_v4.05.xlsm, INLET A7.1 7/8/2021, 12:42 PM Design Information (Input)MINOR MAJOR Type of Inlet Type = Local Depression (additional to continuous gutter depression 'a')aLOCAL =3.0 3.0 inches Total Number of Units in the Inlet (Grate or Curb Opening)No = 1 1 Warning 1 Length of a Single Unit Inlet (Grate or Curb Opening)Lo =4.00 4.00 ft Width of a Unit Grate (cannot be greater than W, Gutter Width) Wo =N/A N/A ft Clogging Factor for a Single Unit Grate (typical min. value = 0.5)Cf-G =N/A N/A Clogging Factor for a Single Unit Curb Opening (typical min. value = 0.1)Cf-C =0.10 0.10 Street Hydraulics: OK - Q < Allowable Street Capacity'MINOR MAJOR Total Inlet Interception Capacity Q = 0.1 0.4 cfs Total Inlet Carry-Over Flow (flow bypassing inlet)Qb =0.0 0.0 cfs Capture Percentage = Qa/Qo =C% = 100 100 % Warning 1: Dimension entered is not a typical dimension for inlet type specified. INLET ON A CONTINUOUS GRADE Version 4.05 Released March 2017 CDOT Type R Curb OpeningCDOT Type R Curb Opening 1 APPENDIX B.3 DETENTION FACILITIES Pond No : Pond 100-yr 0.78 5.00 min 19271 ft3 2.50 acres 0.442 ac-ft Max Release Rate =1.75 cfs Time (min) Ft Collins 100-yr Intensity (in/hr) Inflow Volume (ft3) Outflow Adjustment Factor Qav (cfs) Outflow Volume (ft3) Storage Volume (ft3) 5 9.950 5821 1.00 1.75 525 5296 10 7.720 9032 0.75 1.31 788 8245 15 6.520 11443 0.67 1.17 1050 10393 20 5.600 13104 0.63 1.09 1313 11792 25 4.980 14567 0.60 1.05 1575 12992 30 4.520 15865 0.58 1.02 1838 14028 35 4.080 16708 0.57 1.00 2100 14608 40 3.740 17503 0.56 0.98 2363 15141 45 3.460 18217 0.56 0.97 2625 15592 50 3.230 18896 0.55 0.96 2888 16008 55 3.030 19498 0.55 0.95 3150 16348 60 2.860 20077 0.54 0.95 3413 16665 65 2.720 20686 0.54 0.94 3675 17011 70 2.590 21212 0.54 0.94 3938 17275 75 2.480 21762 0.53 0.93 4200 17562 80 2.380 22277 0.53 0.93 4463 17814 85 2.290 22774 0.53 0.93 4725 18049 90 2.210 23271 0.53 0.92 4988 18284 95 2.130 23675 0.53 0.92 5250 18425 100 2.060 24102 0.53 0.92 5513 18590 105 2.000 24570 0.52 0.92 5775 18795 110 1.940 24968 0.52 0.91 6038 18930 115 1.890 25430 0.52 0.91 6300 19130 120 1.840 25834 0.52 0.91 6563 19271 *Note: Using the method described in FCSCM Chapter 6 Section 2.3 A = Tc = Project Location : Design Point C = Design Storm DETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDF Input Variables Results Required Detention Volume Fort Collins, Colorado 1530-002 Stanford Senior Living Project Number : Project Name : Stormtech Detention Page 1 of 1 1530-002_FAAModified Method.xls Project Title Date: Project Number Calcs By: Client Structure ID Q = Release Rate (cfs)Q = 1.75 cfs C = Discharge Coefficients (unitless)C = 0.65 Aa = Area Allowed of Opening (ft 2) Eh = 6.01 ft g = Gravity (32.2 ft/s 2)Ei = 3.00 ft Eh = High Water Surface Elevation (ft) Ec = 3.25 ft Circular Ei = Elevation of Outlet Invert (ft)Ec = 3.22 ft Rectangular Ec = Elevation of Outlet Centroid (ft) 0.193374191 ft2 27.845884 in2 Orifice Size (in.)6 in.Orifice Height (in.)5 -1/4 in. Area (in2)29.03 sq-in Orifice Width (in.) 5 - 4/8 in. Q 1.75 cfs Area (in2)28.88 sq-in Q 1.75 cfs Aa = Circular Orifice Rectangular Orifice 100-Year Orifice 100-Year Orifice Stanford Senior Living July 12, 2021 1530-002 B. Mathisen 100-yr Outfall A2 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 = 2.50 acres 0.00 7,641 0.00 0.00 Watershed Length =800 ft 1.00 7,641 1.00 0.57 Watershed Length to Centroid = 400 ft 2.00 7,641 2.00 0.86 Watershed Slope =0.020 ft/ft 3.00 7,641 3.00 1.07 Watershed Imperviousness = 64.0%percent 4.00 7,641 4.00 1.25 Percentage Hydrologic Soil Group A = 0.0%percent 5.00 7,641 5.00 1.41 Percentage Hydrologic Soil Group B = 0.0%percent 6.00 7,641 6.00 1.50 Percentage Hydrologic Soil Groups C/D = 100.0%percent 7.00 7,641 7.00 1.67 Target WQCV Drain Time = 40.0 hours 8.00 7,641 8.00 1.79 User Input 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 0.98 1.36 1.71 2.31 2.91 in CUHP Runoff Volume =0.052 0.125 0.198 0.271 0.404 0.539 acre-ft Inflow Hydrograph Volume =N/A 0.125 0.198 0.271 0.404 0.539 acre-ft Time to Drain 97% of Inflow Volume =13.2 14.2 14.1 14.2 14.6 15.1 hours Time to Drain 99% of Inflow Volume =17.3 18.3 18.3 18.3 18.7 19.3 hours Maximum Ponding Depth =0.30 0.50 0.81 1.10 1.74 2.40 ft Maximum Ponded Area =0.18 0.18 0.18 0.18 0.18 0.18 acres Maximum Volume Stored =0.053 0.087 0.140 0.193 0.305 0.420 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 Stanford Senior Living - Pond Fort Collins, CO 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_Data_v2.00 (State Compliance Time).xlsm, Design Data 9/7/2021, 10:15 AM 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 1 2 3 4 5 6 7 8 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 0.1 1 10 100PONDING DEPTH [ft]DRAIN TIME [hr] 100YR 50YR 10YR 5YR 2YR WQCV SDI_Design_Data_v2.00 (State Compliance Time).xlsm, Design Data 9/7/2021, 10:15 AM APPENDIX C WATER QUALITY DESIGN COMPUTATIONS Project Title Date: Project Number Calcs By: City Basins 1 WQCV = Watershed inches of Runoff (inches)64% a = Runoff Volume Reduction (constant) i = Total imperviousness Ratio (i = Iwq/100)0.250 in A =2.50 ac V = 0.0522 ac-ft V = Water Quality Design Volume (ac-ft) WQCV = Water Quality Capture Volume (inches) A = Watershed Area (acres) The Stanford June 17, 2021 1530-002 B. Mathisen Fort Collins Stormtech Detention 2272 cu. ft. Drain Time a = i = WQCV = Figure EDB-2 - Water Quality Capture Volume (WQCV), 80th Percentile Runoff Event 0.231 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 00.10.20.30.40.50.60.70.80.91WQCV (watershed inches)Total Imperviousness Ratio (i = Iwq/100) Water Quality Capture Volume 6 hr 12 hr 24 hr 40 hr ()iii78.019.10.91aWQCV 23 +-= ()iii78.019.10.91aWQCV 23 +-= AV* 12 WQCV   = 40 hr Pond No : Pond 1 WQ 0.78 5.00 min 1927 ft3 2.50 acres 0.04 ac-ft Max Release Rate =0.49 cfs Time (min) Ft Collins WQ Intensity (in/hr) Inflow Volume (ft3) Outflow Adjustmen t Factor Qav (cfs) Outflow Volume (ft3) Storage Volume (ft3) 5 1.425 834 1.00 0.49 146 687 10 1.105 1293 1.00 0.49 293 1000 15 0.935 1641 0.67 0.33 293 1348 20 0.805 1884 0.63 0.30 366 1518 25 0.715 2091 0.60 0.29 439 1652 30 0.650 2282 0.58 0.28 512 1769 35 0.585 2396 0.57 0.28 585 1810 40 0.535 2504 0.56 0.27 659 1845 45 0.495 2606 0.56 0.27 732 1874 50 0.460 2691 0.55 0.27 805 1886 55 0.435 2799 0.55 0.27 878 1921 60 0.410 2878 0.54 0.26 951 1927 65 0.385 2928 0.54 0.26 1025 1903 70 0.365 2989 0.54 0.26 1098 1892 75 0.345 3027 0.53 0.26 1171 1857 80 0.330 3089 0.53 0.26 1244 1845 85 0.315 3133 0.53 0.26 1317 1815 90 0.305 3212 0.53 0.26 1390 1821 95 0.290 3223 0.53 0.26 1464 1760 100 0.280 3276 0.53 0.26 1537 1739 105 0.270 3317 0.52 0.26 1610 1707 110 0.260 3346 0.52 0.26 1683 1663 115 0.255 3431 0.52 0.25 1756 1675 120 0.245 3440 0.52 0.25 1829 1610 *Note: Using the method described in FCSCM Chapter 6 Section 2.3 DETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDF Input Variables Results Required Detention Volume Fort Collins, Colorado 1530-002 The Stanford Project Number : Project Name : Pond 1 A = Tc = Project Location : Design Point C = Design Storm Page 2 of 5 1530-002 Chamber Summary.xlsx Vault IDTotal RequiredWQ Volume(cf)Flow,WQ(cfs)ChamberTypeChamber Release Ratea(cfs)ChamberVolumeb(cf)Installed Camber w/ Aggregatec(cf)Mimimum No. of ChambersdTotal Release Ratee(cfs)Required Storage Volume by FAA Method(cf)Mimimum No. of ChambersfStorage Provided within the Chambersg(cf)Total Installed System Volumeh(cf)Pond1 2272 2.57 MC-3500 0.038 109.90 175.00 13 0.49 1927181978 2275a. Release rate per chamber, limited by flow through geotextile with accumulated sediment.b. Volume within chamber only, not accounting for void spaces in surrounding aggregate.c. Volume includes chamber and void spaces (40%) in surrounding aggregate, per chamber unit.d. Number of chambers required to provide full WQCV within total installed system, including aggregate.e. Release rate per chamber times number of chambers.f. Number of chambers required to provide required FAA storage volume stored within the chamber only (no aggregate storage).g. Volume provided in chambers only (no aggregate storage). This number must meet or exceed the required FAA storage volume.h. System volume includes total number of chambers, plus surrounding aggregate. This number must meet or exceed the required WQCV.Chamber Configuration SummaryP:\1530-002\Drainage\WatQual\1530-002 Chamber Summary.xlsx Chamber Dimensions SC-160 SC-310 SC-740 MC-3500 MC-4500 Width (in)34.0 34.0 51.0 77.0 100.0 Length (in)85.4 85.4 85.4 90.0 52.0 Height (in)16.0 16.0 30.0 45.0 60.0 Floor Area (sf)20.2 20.2 30.2 48.1 36.1 Chamber Volume (cf)6.9 14.7 45.9 109.9 106.5 Chamber/Aggregate Volume (cf)29.3 29.3 74.9 175.0 162.6 Flow Rate* 0.35 gpm/sf 1 cf =7.48052 gal 1 gallon =0.133681 cf 1 GPM = 0.002228 cfs *Flow rate based on 1/2 of Nov 07 QMAX in Figure 17 of UNH Testing Report SC-160 SC-310 SC-740 MC-3500 MC-4500 Flow Rate/chamber (cfs) 0.015724 0.015724 0.023586 0.037528 0.028159 end caps have a volume of 108.7 cu. ft. StormTech Chamber Data Chamber Flow Rate Chamber Flow Rate Conversion (gpm/sf to cfs) end caps have a volume of 45.1 cu. ft. P:\1530-002\Drainage\WatQual\1530-002 Chamber Summary.xlsx APPENDIX D EROSION CONTROL REPORT Stanford Senior Living Erosion Control Report A comprehensive Erosion and Sediment Control Plan (along with associated details) will be included with the final construction drawings. It should be noted, however, that any such Erosion and Sediment Control Plan serves only as a general guide to the Contractor. Staging and/or phasing of the BMPs depicted, and additional or different BMPs from those included may be necessary during construction, or as required by the authorities having jurisdiction. It shall be the responsibility of the Contractor to ensure erosion control measures are properly maintained and followed. The Erosion and Sediment Control Plan is intended to be a living document, constantly adapting to site conditions and needs. The Contractor shall update the location of BMPs as they are installed, removed or modified in conjunction with construction activities. It is imperative to appropriately reflect the current site conditions at all times. The Erosion and Sediment Control Plan shall address both temporary measures to be implemented during construction, as well as permanent erosion control protection. Best Management Practices from the Volume 3, Chapter 7 – Construction BMPs will be utilized. Measures may include, but are not limited to, silt fencing along the disturbed perimeter, gutter protection in the adjacent roadways and inlet protection at proposed storm inlets. Vehicle tracking control pads, spill containment and clean-up procedures, designated concrete washout areas, dumpsters, and job site restrooms shall also be provided by the Contractor. Grading and Erosion Control Notes can be found on Sheet CS2 of the Utility Plans. The Utility Plans at final design will also contain a full-size Erosion Control Plan as well as a separate sheet dedicated to Erosion Control Details. In addition to this report and the referenced plan sheets, the Contractor shall be aware of, and adhere to, the applicable requirements outlined in any existing Development Agreement(s) of record, as well as the Development Agreement, to be recorded prior to issuance of the Development Construction Permit. Also, the Site Contractor for this project will be required to secure a Stormwater Construction General Permit from the Colorado Department of Public Health and Environment (CDPHE), Water Quality Control Division – Stormwater Program, before commencing any earth disturbing activities. Prior to securing said permit, the Site Contractor shall develop a comprehensive StormWater Management Plan (SWMP) pursuant to CDPHE requirements and guidelines. The SWMP will further describe and document the ongoing activities, inspections, and maintenance of construction BMPs. APPENDIX E ADDITIONAL REFERENCES This unofficial copy was downloaded on Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 Jun-30-2020 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 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, Colorado The Stanford Natural Resources Conservation Service December 2, 2020 9 Custom Soil Resource Report Soil Map 44875804487600448762044876404487660448768044877004487580448760044876204487640448766044876804487700493880 493900 493920 493940 493960 493980 494000 494020 494040 494060 494080 494100 493880 493900 493920 493940 493960 493980 494000 494020 494040 494060 494080 494100 40° 32' 24'' N 105° 4' 20'' W40° 32' 24'' N105° 4' 10'' W40° 32' 19'' N 105° 4' 20'' W40° 32' 19'' N 105° 4' 10'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 50 100 200 300 Feet 0 15 30 60 90 Meters Map Scale: 1:1,050 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 73 Nunn clay loam, 0 to 1 percent slopes 0.4 18.8% 74 Nunn clay loam, 1 to 3 percent slopes 1.9 81.2% Totals for Area of Interest 2.4 100.0% 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 11 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 13 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 14 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 15 MAP PACKET EXISTING DRAINAGE EXHIBIT DR1 – DRAINAGE EXHIBIT D VAULTF.O. D H ex D D TCONTROLIRR D MONROE DRIVE (PRIVATE ROAD)STANFORD ROADPORTION OF LOT 3 STRACHAN SUBDIVISION THIRD FILING REC. NO. 20190052896 36" RCP 3 6 " R C P EX STRM MH 1 RIM = 5009.54 INV. IN = 5002.30 (W) INV. IN = 5002.55 (N) INV. IN = 5002.77 (NW) INV. OUT = 5022.27 (SE) EXISTING STORM STRUCTURE PER STRACHAN 3RD FILING EXISTING 30"X36" HERCP EX STRM MH 2 RIM = 5005.30 BTM BOX = 5002.21 PORTION OF LOT 3 STRACHAN SUBDIVISION THIRD FILING REC. NO. 20180064205 TRACT J FOOTHILLS MALL REDEVELOPMENT SUB. FILING NO. 3 LOT 6 FOOTHILLS MALL REDEVELOPMENT SUB. LOT 2 PRIVATE ROAD REC.NO. 88042989 & PORTION OF PARCEL 1 EXISTING INLET EXISTING INLET HORSETOOTH ROAD(3.7%)(2 .7% ) ( 1 . 9% ) (2 .1% ) (4 . 0% )(2.5%)(6.4%)NORTH ( IN FEET ) 0 1 INCH = 80 FEET 80 80 160 240 GRAPHIC SCALE: LEGEND: PROPERTY BOUNDARY EXISTING STORM INLET EXISTING CURB & GUTTER EXISTING SLOPE EXISTING MAJOR CONTOUR RUNOFF SUMMARY: A2 a3DESIGN POINT DRAINAGE BASIN ID DRAINAGE BASIN MINOR/MAJOR COEFF. EXISTING STORM SEWER BASIN DELINEATION 1. REFER TO "FINAL DRAINAGE REPORT FOR STANFORD SENIOR LIVING" PREPARED BY NORTHERN ENGINEERING ON 09/08/2021 FOR ADDITIONAL INFORMATION. 2. FOR HISTORIC RUNOFF CALCULATION ALL IMPERVIOUS AREA WAS ASSUMED TO BE PERVIOUS. NOTES: GRAVEL CONCRETE ASPHALT EXISTING DRAINAGE EXHIBIT FORT COLLINS, CO STANFORD SENIOR LIVING E N G I N E E R N GI EHTRON R N 09.08.2021 P:\1530-002\DWG\DRNG\1530-001_EX-DRNG.DWG DRAINAGE BASIN AREA (2.0%) BASIN TOTAL AREA (acres) Tc2 (min) Tc100 (min) C2 C100 Q2 (cfs) Q10 (cfs) Q100 (cfs) H 2.50 11.7 11.7 0.25 0.31 1.31 2.23 5.65 D D D UDU D MONITOR I N G W E L L TRAFFIC R A T E D T T T T D VAULT ELEC VAULT ELECELEC T S D a d 121 MC-3500 STORMTECH CHAMBERS EXISTING STORM STRUCTURE BUILT PER STRACHAN SUBDIVISION THIRD FILING EXISTING 36" RCP EXISTING 36" RCP EXISTING STORM MH ISOLATOR ROWS (22 MC-3500 STORMTECH CHAMBERS) 1' CURB CUT 1' CURB CUT 30"x36" HERCP MONROE DRIVE (PRIVATE ROAD)STANFORD ROADSTORM LINE OUTFALL f PORTION OF LOT 3 STRACHAN SUBDIVISION THIRD FILING REC. NO. 20190052896 PORTION OF LOT 3 STRACHAN SUBDIVISION THIRD FILING REC. NO. 20180064205 UNPLATTED REC. NO. 2015002744 g STORM LINE CONNECTION TO COURTYARD b e os h11 h1 h2 h3 h4 h5 h6 h7 h12 h8 h9 h10 c C A E D F G B H1 OS H2 H3 H4 H5 H6 H8 H9 H10 H11 H7 H12 STORM LINE A SEE SHEET ST1 STORM LINE A SEE SHEET ST1 STORM LINE A4 SEE SHEET ST2 PROPOSED DRAINAGE EASEMENT EXISTING 36" RCP WQ BASIN A3 WQ BASIN A3.1 100-YR OUTFALL A2 INLET A7.1 INLET A7 INLET A8 INLET A12 INLET A16 INLET A10.5 INLET A10.4.1 INLET A10.5.1 INLET A10.6 INLET A10.7 INLET A4.10 INLET A4.7 INLET A4.3 INLET A4.2 INLET A4.1 INLET A5 INLET A16.1 INLET A14.1 INLET A17 e e COURTYARD A SEE SHEET G2 COURTYARD B SEE SHEET G2 STORMTECH CHAMBERS SEE SHEET SUB1 SWALE INLET A17.1 PROPOSED 10' DRAINAGE EASEMENT PROPOSED OFFSITE STORM SEWER EASEMENT SheetSTANFORD SENIOR LIVINGThese drawings areinstruments of serviceprovided by NorthernEngineering Services, Inc.and are not to be used forany type of constructionunless signed and sealed bya Professional Engineer inthe employ of NorthernEngineering Services, Inc.NOT FOR CONSTRUCTIONREVIEW SETENGINEERNGIEHTRONRNFORT COLLINS: 301 North Howes Street, Suite 100, 80521GREELEY: 820 8th Street, 80631970.221.4158northernengineering.comof 19 DR1 DRAINAGE EXHIBIT19 CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UTILITIES. CALL UTILITY NOTIFICATION CENTER OF COLORADO Know what'sbelow. before you dig.Call R NORTH ( IN FEET ) 0 1 INCH = 30 FEET 30 30 60 90 PROPOSED CONTOUR EXISTING STORM SEWER PROPOSED STORM SEWER PROPOSED SWALE EXISTING CONTOUR PROPOSED CURB & GUTTER OVERLAND FLOW PROPOSED STORM INLET EXISTING LOT LINE BASIN AREA RUNOFF SUMMARY: A a EXISTING RIGHT OF WAY DESIGN POINT BASIN ID BASIN MINOR AND MAJOR C COEFFICIENTS PROPERTY BOUNDARY LEGEND: 1.REFER TO THE "FINAL DRAINAGE REPORT FOR STANFORD SENIOR LIVING" BY NORTHERN ENGINEERING DATED 09/08/2021 FOR ADDITIONAL INFORMATION. 2.STANFORD SENIOR LIVING PROJECT WILL BE DETAINING THE DIFFERENCE BETWEEN THE HISTORIC 10-YEAR EVENT AND THE DEVELOPED 100-YEAR EVENT. 3.LID MEASURES ARE PROVIDED VIA ISOLATOR ROWS. 4.ALL PROPOSED STORM SEWER AND STORMTECH SYSTEM ARE TO BE PRIVATELY OWNED AND MAINTAINED. NOTES: CONCENTRATED FLOW BASIN DELINEATION BASIN TOTAL AREA (acres) Tc2 (min) Tc100 (min) C2 C100 Q2 (cfs) Q100 (cfs) A 0.12 5.0 5.0 0.36 0.42 0.13 0.52 B 0.05 5.0 5.0 0.82 0.87 0.12 0.46 C 0.09 5.0 5.0 0.95 1.00 0.24 0.90 D 0.41 5.0 5.0 0.37 0.43 0.43 1.76 E 0.27 5.0 5.0 0.83 0.88 0.65 2.40 F 0.05 5.0 5.0 0.80 0.85 0.11 0.43 G 0.19 5.0 5.0 0.42 0.48 0.23 0.93 H1 0.05 5.0 5.0 0.95 1.00 0.14 0.51 H2 0.11 5.0 5.0 0.95 1.00 0.28 1.05 H3 0.05 5.0 5.0 0.95 1.00 0.13 0.48 H4 0.11 5.0 5.0 0.95 1.00 0.29 1.08 H5 0.05 5.0 5.0 0.95 1.00 0.14 0.50 H6 0.04 5.0 5.0 0.95 1.00 0.12 0.45 H7 0.04 5.0 5.0 0.95 1.00 0.12 0.44 H8 0.06 5.0 5.0 0.95 1.00 0.17 0.61 H9 0.19 5.0 5.0 0.95 1.00 0.53 1.93 H10 0.19 5.0 5.0 0.95 1.00 0.53 1.94 H11 0.09 5.0 5.0 0.95 1.00 0.24 0.87 H12 0.16 5.0 5.0 0.88 0.93 0.41 1.51 OS 0.15 5.0 5.0 0.27 0.33 0.11 0.48 Combined Basins Basins A-OS 2.50 5.0 5.0 0.72 0.77 5.13 19.17