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TIMBERLINE STORAGE - FDP - FDP160038 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT
FINAL DRAINAGE REPORT TIMBLERLINE STORAGE Fort Collins, Colorado September 21, 2016 Prepared for: Brandon Grebe GYS LLC Real Estate / Development / Consulting 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: 1269-001 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. September 21, 2016 City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, Colorado 80521 RE: Final Drainage Report for Timberline Storage Dear Staff: Northern Engineering is pleased to submit this Final Drainage and Erosion Control Report for your review. This report accompanies the Final Review submittal for the proposed Timberline Storage. This report has not been prepared in accordance to Fort Collins Stormwater Criteria Manual (FCSCM), and Northern Engineering Services, Inc. is requesting modification for the Timberline Storage project be made. We understand that review by the City is to assure general compliance with standardized criteria contained in the FCSCM as well as maintaining the overall Master Drainage Plan set forth by the City. If you should have any questions as you review this report, please feel free to contact us. Sincerely, NORTHERN ENGINEERING SERVICES, INC. Nicholas W. Haws, PE Blaine Mathisen Project Manager Project Engineer Timberline Storage 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 ................................................................................... 5 A. Regulations........................................................................................................................................ 5 B. Four Step Process .............................................................................................................................. 6 C. Development Criteria Reference and Constraints ............................................................................ 7 D. Hydrological Criteria ......................................................................................................................... 7 E. Hydraulic Criteria .............................................................................................................................. 8 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 ...................................................................................................... 12 A. Compliance with Standards ............................................................................................................ 12 B. Drainage Concept ............................................................................................................................ 12 References ....................................................................................................................... 14 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 Timberline Storage Final Drainage Report LIST OF TABLES AND FIGURES: Figure 1 – Aerial Photograph ................................................................................................ 1 Figure 2– Proposed Site Plan ................................................................................................ 3 Figure 3 – Existing FEMA Floodplains .................................................................................... 4 Figure 4 – Existing City Floodplains ....................................................................................... 4 Figure 5 - LID Table ............................................................................................................ 6 MAP POCKET: C8.00 - Drainage Exhibit C8.01 – Historic Drainage Exhibit Timberline Storage Final Drainage Report 1 I. GENERAL LOCATION AND DESCRIPTION A. Location 1. Vicinity Map Figure 1 – Aerial Photograph 2. Timberline Storage project is located in the southwest quarter of section 20, Township 7 North, Range 68 West of the 6th P.M., City of Fort Collins, County of Larimer, State of Colorado. 3. The project site is located south of Prospect Road and east of South Timberline Road. More specifically it is at the corner of Specht Point Road and Midpoint Drive. Timberline Storage will have the address of 1615 Specht Point Road. 4. Currently the existing lot has a 24” RCP storm pipe running south to north up the middle of the property but there are no water quality facilities currently on site. However, north of the site and currently connected to the existing 24” RCP there is a stormceptor that provides water quality for storm runoff. The existing 24” RCP was designed to convey runoff for future development in this area according to Spring Creek Center, P.U.D. Final Drainage Plan submitted by Northern Engineering Services which was approved for the overall area in May, 1999. The Timberline Storage project follows the previous drainage design as to ensure no negative downstream impacts occur. The project is currently bordered to the north by commercial properties (Gamble Pet Clinic, Curves, and Shell Gas), to the south by Larimer County Community Correctional Facility, to the east by Specht Point Road and to the west by a Car Wash. Timberline Storage Final Drainage Report 2 B. Description of Property 1. Timberline Storage is approximately 4.82 net acres. 2. Timber Line Storage consists of two separate lots (Lot 6 and Lot 7). There is no off- site drainage entering the property. Currently runoff generated from the project has a split flow. Roughly half heads southeast and eventually meets up with the Cache La Poudre while the other half traditionally flows north towards Spring Creek. The proposed grading for Timberline Storage will, to the greatest extent possible, maintain these drainage patterns. 3. According to the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Soil Survey, 97.4 percent of the site consists of Caruso clay loam, which falls into Hydrologic Soil Groups D. The other 2.4 percent of the site consists of Loveland clay loam, which falls into Hydrologic Soils Group C. Earth Engineering Consultants, dated May 31, 2016, performed a site-specific subsurface exploration. Through their exploration, silty/clayey sand, sandy lean clay and/or lean clay subsoils were encountered. 4. The proposed development will clear all of the existing vegetation. The proposed project will include two climate controlled storage buildings, nine storage unit buildings, and one pad ready site with associated parking. Water quality will be provided on-site by use of StormTech chambers designed for water quality, and surrounding green space. The remaining runoff not being treated by StormTech chambers, will be treated in either the existing stormceptor located to the north of the project, by the two detention ponds designed for Spring Creek Center P.U.D, or by the pond designed for the Prospect Park East P.U.D. Stormwater runoff will be detained in two separate detention systems. Both will consist of underground StrormTech chambers. The detention pond draining to the east will be restricted to the previously approved rate. The detention pond draining to the north will be restricted to the capacity of the existing storm sewer system. Timberline Storage Final Drainage Report 3 Figure 2– Proposed Site Plan 5. No irrigation facilities or major drainageways are within the property limits. 6. The project site is within an Employment District (E) Zoning District. The proposed use is permitted as a secondary use within this zone district. C. Floodplain 1. The subject property does not lie within a 100 year FEMA or City regulatory floodplain. 2. The FEMA Panel 08069C0983H illustrates the proximity of the project site to the nearest FEMA delineated regulatory floodplain. It is noted that the vertical datum utilized for site survey work is the City of Fort Collins Benchmark #36-92 Elevation = 4981.80 (NAVD 88) Timberline Storage Final Drainage Report 4 Figure 3 – Existing FEMA Floodplains Figure 4 – Existing City Floodplains Timberline Storage Final Drainage Report 5 II. DRAINAGE BASINS AND SUB-BASINS A. Major Basin Description 1. Timberline Storage straddles the boundary between the Spring Creek Basin and the Cache La Poudre Basin. B. Sub-Basin Description 1. Timberline Storage historically split drains either southeast towards the intersection of Specht Point Road and Midpoint Drive or north towards Spring Creek. 2. The project site where Timberline Storage is located has already been analyzed by the previous development, Spring Creek Center P.U.D. According to the Spring Creek Center P.U.D. Final Drainage Plan Timberline Storage falls within Basins 1, 2, 3, 4, 8, 9, 10 and 13. However, the majority of the project site is within Basins 2, 3, 4, 8 and 10. 3. Basin 1 was previously designed to discharge directly into Specht Point Road. This concept will be maintained with the proposed development. 4. Basin 2, 3 and 4 were designed to be detained and released at a restricted rate of 3.14 cfs. Detention will be provided and a restricted release of 3.14 cfs into Spetch Point Road will be applied. 5. Basin 8 was previously designed to drain 13.20 cfs to Inlet 8. This pipe has been constructed and will be utilized for the Timberline Storage project. 6. Basin 10 was previously designed to drain 17.80 cfs to Inlet 10 which is located northwest of the project site. This is an existing pipe and it will continue to be utilized. 7. Inlets 8 and 10 merge at Inlet 9 which carries the flow north towards an existing stormceptor. The stormceptor was the original water quality amenity associated with Basins 8, 9 and 10. With new LID requirements, Timberline Storage will be providing additional water quality through use of StormTech chamber isolator rows. 8. A more detailed description of the projects proposed drainage patterns follows in Section IV.A.4., below. 9. No drainage is routed onto the property from the surrounding properties. A full-size copy of the Historic and Proposed Drainage Exhibit can be found in the Map Pocket at the end of this report. III. DRAINAGE DESIGN CRITERIA A. Regulations There are several provisions outside of FCSCM being proposed with Timberline Storage. First off, due to existing infrastructure and previously approved plans from Spring Creek Center P.U.D., Timberline Storage will be releasing the majority of the on-site runoff through the existing storm system and releasing directly into Spring Creek. A portion of the site will be released directly into Specht Point Road at the previous approved release rate of 3.14 cfs. The remaining area drains off-site has been reduced from the original design. Timberline Storage Final Drainage Report 6 B. Four Step Process The overall stormwater management strategy employed with the Timberline Storage 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, east, and south portion of the site to reduce the overall impervious area and to minimize directly connected impervious areas (MDCIA). Routing flows, to the extent feasible, through StormTech chambers with an assumed porosity of 0% to accommodate for sediment buildup. Providing regional detention to increase time of concentration, promote infiltration and reduce loads on existing storm infrastructure. Routing runoff from the proposed roofs into StormTech chambers to promote infiltration, biological uptake, and evapotranspiration. A more specific breakdown in how LID is being handled within the limits of disturbance for Timberline Storage can be found below. Figure 5 - LID Table Please note that these areas are associated with the area that falls within both our project boundary as well as within the limits of disturbance. Therefore, not all of these areas are indicative of their entire basin area, which is described in a later section. Additionally, a map indicating how these areas were calculated is included in Appendix C. 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. A majority of the stormwater that is generated on the project site will be routed into StormTech chambers designed for water quality. Water quality for basins being routed off-site will received water quality either by the Stormceptor located to the north of the site or by the regional ponds design for the overall Center. Design Point Basin ID Basin Area within Limits Of Disturbance Treatment Type LID System Area Treated by LID System Percent of Site Treated by LID System Water Quality Treatment Type Area Treated with Water Quality Run-on Area Ratio (1:1 Max) 1 N1 0.214 ac. Grass Buffer Yes 0.214 ac. 6% Extended Detention 0.214 ac. 0.0 5 N5 0.018 ac. Grass Buffer Yes 0.018 ac. 0% Extended Detention 0.018 ac. 0.0 n2-4 N2-4 0.931 ac. StormTech Chambers Yes 0.931 ac. 26% StormTech Chambers 0.931 ac. 0.0 n8.a N8.a 0.699 ac. StormTech Chambers Yes 0.699 ac. 19% StormTech Chambers 0.699 ac. 0.0 n8.b N8.b 1.347 ac. StormTech Chambers Yes 1.347 ac. 37% StormTech Chambers 1.347 ac. 0.0 9 N9 0.096 ac. Grass Buffer Yes 0.096 ac. 3% Stormceptor 0.096 ac. 0.0 10 N10 0.259 ac. N/A No N/A 0% Stormceptor 0.259 ac. 0.0 13 N13 0.301 ac. Grass Buffer Yes 0.301 ac. 8% Extended Detention 0.301 ac. 0.2 Timberline Storage Final Drainage Report 7 Step 3 – Stabilize Drainageways As stated in Section I.B.5, above, there are no major drainageways in the subject site. While this step may not seem applicable to Timberline Storage, the proposed project indirectly helps achieve stabilized drainageways nonetheless. Once again, site selection has a positive effect on stream stabilization. By repurposing an undeveloped, under- utilized site with minimal existing stormwater infrastructure, combined with LID, the likelihood of bed and bank erosion is greatly reduced. 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. The Timberline Storage project includes a several buildings and garages with an associated drive and parking area, all of which will require the need for site specific source controls including: A localized trash collection system through use of individual bins stored internally. C. Development Criteria Reference and Constraints 1. The overall project, Spring Creek Center P.U.D. was previously designed by Northern Engineering and approved in May, 1999. 2. All adjacent properties are included within the Spring Creek Center P.U.D. Drainage Report and Plan. 3. The subject property is essentially an "in-fill" development project as the property is surrounded by currently developed properties. As such, several constraints have been identified during the course of this analysis that will impact the proposed drainage system including: Existing elevations along the north, south, east, and west property lines will be maintained. Previously approved drainage patterns of the site will be maintained. The runoff from the proposed site will be utilizing existing storm sewer constructed with the overall development. 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. Two 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. 5. No other assumptions or calculation methods have been used with this development that are not referenced by current City of Fort Collins criteria. Timberline Storage Final Drainage Report 8 E. Hydraulic Criteria 1. As previously noted, the subject property has been previously analyzed with the Spring Creek Center P.U.D development. Timberline Storage will be using existing infrastructure and existing drainage basins to route the storm runoff either to Spring Creek or towards Cache La Poudre. 2. The proposed drainage facilities associated with the Timberline Storage project are in accordance with the criteria outlined in the FCSCM and/or the Urban Drainage and Flood Control District’s (UDFCD) 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. The Timberline Storage 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 Timberline Storage development is requesting modification at this time. Timberline Storage is requesting that this project be held to the same standards that were present at the time of the Spring Creek Center P.U.D development. Timberline Storage is planning on using previously approved release rates as well as utilizing current onsite infrastructure to convey flows towards their ultimate discharge locations. IV. DRAINAGE FACILITY DESIGN A. General Concept 1. The main objectives of the Timberline Storage drainage design are to maintain previously designed drainage patterns and ensure no adverse impacts to any adjacent properties or existing infrastructure. 2. As previously mentioned, there are no off-site flows draining onto the project site. 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 Timberline Storage project closely represents the previously approved drainage plan for Spring Creek Center P.U.D. and therefore the proposed basin notation and naming conventions has been prepared to represent the previously approved drainage report. Currently two basins encompass the majority of the site, Basins N8 and Basins N4-2. These two basins represent the previously approved Basin 8 and Basin 2, Basin 3, and Basin 4. The other basins, Basin N1, N5, N9, N10, N11, and N13 discharge off the proposed site. Due to the fact that Basins N9, N10 and N11 are discharging into the same storm system, those basins were analyzed with up to date storm intensities. As for Basins N1, N5 and N13, Timberline Storage has been graded to maintain the same drainage characteristics as the previously approved Spring Creek Center P.U.D plans. Basin N1 Timberline Storage Final Drainage Report 9 Basin N1 is located along the eastern edge of the project site and is composed of the landscape area behind the storage units that closely represent the original design of the Spring Creek Center P.U.D. Stormwater is routed entirely via overland flow into Specht Point Road and is ultimately routed to the detention pond located within Prospect Park East P.U.D. The area draining to the previously approved design point has been decreased by the current design, therefore decreasing the amount of stormwater runoff anticipated for this area. Basin N5 Basin N5 is located on the northern side of the project site and is composed of the landscape area behind the storage units and existing drive entrance which is indicative of the portion of Basin 5 from the Spring Creek Center P.U.D. Stormwater is routed entirely via overland flow and discharges directly into the private drive. Basin N5 is draining to a previously approved design point has been decreased by the current design, therefore decreasing the amount of stormwater runoff conveyed to Pond 6 within the Spring Creek Center P.U.D development prior to discharging into the Poudre Ponds. Basin N13 Basin N13 is located on the southern side of the project site and is composed of the landscape area behind the storage units and represents the original design of the Spring Creek Center P.U.D (Basin 13). Stormwater is routed entirely via overland flow and into Midpoint Drive and is ultimately routed to the detention pond located within Prospect Park East P.U.D. Basin N13 is draining to a previously approved design point. However, the area has been decreased by the current design, therefore the overall amount of stormwater conveyed to Prospect Park East P.U.D is reduced. Basin N11 Basin N11 is located west of the project site and is associated with Basin 11 from the original design of the Spring Creek Center P.U.D. Stormwater is routed via overland and gutter flow as previously designed. All previous approved overall areas, percent imperviousness and time of concentrations were used in modeling the runoff from Basin N11, in order to analyze the existing storm sewer capacity, current storm intensities were incorporated to the proposed design. These increased flows were used with the peak runoff rates generated from Basin N10 and analyzed to ensure the existing storm sewer system, based on as-built information, could adequately convey the peak runoff from design point 10. All runoff from this basin is discharge directly into Spring Creek before the peak upstream events, as previously approved. Water quality from this basin is achieved from the existing stormceptor as previously approved. No improvements are being proposed within this basin. The only reason it is included in this report is to convey that adequate analysis was performed on the existing storm infrastructure to guarantee it is not overloaded. Basin N10 Timberline Storage Final Drainage Report 10 Basin N10 is located on site and consists of a climate control storage building and the future lot to the west. This closely represents the original design of the Spring Creek Center P.U.D Basin 10. Stormwater is routed via overland and gutter flow as previously designed. The time of concentrations was used from the original analysis, but in order to analyze the existing storm sewer system, up to date storm intensities and the overall area from Basins 10 and 11 were incorporated to the proposed design. These increased flows (because of up to date rainfall intensities) were incorporated with the peak runoff rates generated from Basin N10 and N11 and analyzed to ensure the existing storm sewer system, based on as-built information, could adequately convey the peak runoff. All runoff from this basin is discharge directly into Spring Creek before the peak upstream events, as previously approved. Water quality for this basin is provided via the existing stormceptor. Basin N4-2 Basin N4-2 is located on site and is associated with Basins 2, 3 and 4 of the previous design. In the previous design, these basins were detained and discharged at a restricted rate of 3.14 cfs into Specht Point Road. This approved concept was utilized with the proposed design. All runoff from Basin N4-2 is routed via overland and gutter flow and routed into a StormTech chamber system designed for both underground detention and water quality. The chambers are sized to capture both the storm water quality and the major storm event. The overall release from this basin is restricted to the 3.14 cfs as previously approved. Basin N8 Basin N8 is located completely on site and is associated with Basins 8 of the previous design. In the previous design, these basins were free released into design point 8 (area inlet) and discharged into Spring Creek before the peak upstream events. Overall area, time of concentration, percent of imperviousness and current runoff rates were used to analyze the capacity of the existing stormwater pipe. All runoff from Basin N8 is routed via overland and gutter flow and intercepted by a storm sewer system and discharged into a StormTech chamber system designed for both underground detention and water quality. The chambers are sized to capture both the storm water quality and the major storm event. The overall release from this basin is restricted to the capacity of the existing storm sewer system (20 cfs). For hydraulic sizing Basin N8 was subdivided into two basins; N8.a and N8.b. Both sub-basins release from the same weir controlled manhole that connects to the existing infrastructure and conveys the flows to the ultimate design point, Spring Creek. B. Specific Details 1. The main drainage problems associated with this project site is the deficiency of water quality present on the Timberline Storage site. Currently the site split drains either north towards Spring Creek or east towards Specht Point Road. The proposed site will mitigate these issues by instituting the following water quality devices: Water quality for Basin N2-4 will be provided via underground StromTech chambers. Water quality for Basin N8 will be provided via underground StromTech chambers. Timberline Storage Final Drainage Report 11 Water quality for Basins N10 will be provided via the stormceptor located to the north of the project site. Basin N9 consists of the landscape behind the storage units and will be treated for water quality via the stormceptor located to the north of the project site. Basin N5 consists of the landscape behind the storage units and will be treated for water quality via the pond, Pond 6 designed for Spring Creek Center P.U.D., located to the north of the project site. Basins 1 and 13 consists of the landscape behind the storage units and will be treated by the regional pond designed for Prospect Park East P.U.D., located east of the project site. 2. As previously mentioned, this project was designed within Spring Creek Center P.U.D. with a portion of the runoff to be routed to the east into Prospect Park East P.U.D. at a restricted rate, while the remaining portion was routed to the north into Spring Creek. The portion of the site being routed to the east (previous Basins 2, 3 and 4) were detained and released at 3.14 cfs into Spetch Point Road. This flow rate was used to size the detention volume required for Basin N2-4. The portion of the site being routed to the north (previous Basins 8, 9, 10 and 11) were routed through StormTech Cambers and released directly into Spring Creek in order to beat the upstream peak runoff. This storm sewer was adequately sized to route the peak runoff from Basins 8, 9, 10, and 11 using the rainfall requirements from 1999. For the proposed project, the storm sewer was reanalyzed per the proposed construction and with the current rainfall intensities. The existing pipe has capacity to route the peak runoff generated from Basins N9, N10 and N11 and 20.0 cfs generated from Basin N8. This flow rate was used to size the detention volume required for Basin N8. 3. Detention Pond Calculations Detention will be provided onsite in the form of underground detention for Basins N8 and N2-4. The remaining basins will be free released from the project site, as those basins are being decreased in size from the original design and have no additional impervious area drains to these basins. See Appendix B for an exhibit showing these areas. Underground Pond N2-4 The FAA method was used to size the pond for detention. Calculations for Pond N2- 4, based on characteristics of Basin N2-4 and with an adjusted release rate of 3.14 cfs (previously designed release rate of Basins 2, 3 and 4 from Spring Creek Center PUD) results in a detention volume of 4,278 cu. ft. The dentition volume for this pond will be stored underground within StormTech chambers and discharge directly into Specht Point Road as previously designed. Underground Pond N8 The FAA method was used to size the pond for detention. Calculations for Pond N8, based on characteristics of Basin N8 and with an adjusted release rate of 20.0 cfs (capacity of the existing storm sewer system at design N8) results in a detention volume of 449 cu. ft. The dentition volume for this pond will be stored underground within StormTech chambers and discharge into the existing storm system and into Spring Creek as previously designed. 4. Water Quality Results Timberline Storage Final Drainage Report 12 Basin N2-4 Basin N2-4 has water quality provided exclusively via StormTech chambers. Following UDFCD standards for a 12-hour drain time, a Water Quality Capture Volume of 1209 cu. ft. is required. Using SC-160 StormTech chambers designed for water quality, 1231 cu. ft. is provided within the isolator rows. Basin N8 Basin N8 was subdivided into two sub-basins Sub Basins N.8a and N.8b to calculate the water quality volumes required to be stored in two different StormTech systems. Following UDFCD standards for a 12-hour drain time, a Water Quality Capture Volume of 880 cu. ft. and 1675 cu. ft. is required for sub-basins N8.a and N8.b respectively. Using SC-740 StormTech chambers designed for water quality, 899 cu. ft. and 1723 cu. ft. is provided within the isolation rows. Following Fort Collins LID standards 100% of Basins N2-4 and N8 are being treated by LID. Basin N10 will be treated by the stormceptor located to the north of the site as previously designed. The basins that are releasing off-site will either be treated by a regional pond located in Prospect Park East P.U.D. or the existing water quality pond located within Spring Creek Center P.U.D. resulting in the site being treated 100% for water quality. 5. In the case that the area inlet within Basin N2-4 should become clogged, runoff from this basin will overtop the asphalt and be routed directly into Spetch Point Road. 6. In the case that the area inlets within Basin N8 should become clogged, runoff from this basin will overtop and be routed directly into Midpoint Drive via the existing emergency access. V. CONCLUSIONS A. Compliance with Standards 1. The drainage design proposed with the Timberline Storage project does not comply with the current City of Fort Collins’ Stormwater Criteria Manual. To the extent feasible, all on-site basins were reanalyzed with the current rainfall requirements. The small portion draining off-site has decreased in size from the original design. An exhibit to illustrate this reduction has been included in Appendix B. 2. The drainage design proposed with the Timberline Storage project complies with the City of Fort Collin’s Master Drainage Plan for the Spring Creek and Cache La Poudre Basins. 3. There are no regulatory floodplains associated with the Timberline Storage development. 4. The drainage plan and stormwater management measures proposed with the Timberline Storage development are compliant with all applicable State and Federal regulations governing stormwater discharge. B. Drainage Concept 1. The drainage design proposed with this project will not negatively impact any downstream areas. Detention will be provided for Basin N2-4 to restrict runoff to the previously designed release of 3.14 cfs. Detention will be provided for Basin N8 to Timberline Storage Final Drainage Report 13 ensure the existing pipe has capacity to convey the peak runoff from Basins N8, N9, N10 and N11 as previously designed. Timberline Storage Final Drainage Report 14 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. 174, 2011, 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. Geotechnical Exploration Report Proposed Midpoint Self-Storage Facility, May 31, 2016, Earth Engineering Consultants, LLC APPENDIX A HYDROLOGIC COMPUTATIONS Timberline Storage CHARACTER OF SURFACE: Runoff Coefficient Percentage Impervious Project: Timeberline Storage Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: B. Mathisen Asphalt ……....……………...……….....…...……………….………………………………….0.. 95 100% Date: Concrete …….......……………….….……….………………..….………………………………… 0.95 90% Gravel ……….…………………….….…………………………..……………………………….0.. 50 40% Roofs …….…….………………..……………….…………………………………………….. 0.95 90% Pavers…………………………...………………..…………………………………………….. 0.40 22% Lawns and Landscaping Sandy Soil ……..……………..……………….…………………………………………….. 0.15 0% Clayey Soil ….….………….…….…………..………………………………………………. 0.25 0% 2-year C f = 1.00 100-year C f = 1.25 Basin ID Basin Area (s.f.) Basin Area (ac) Area of Asphalt (ac) Area of Concrete (ac) Area of Roofs (ac) Area of Gravel (ac) Area of Pavers (ac) Area of Lawns and Landscaping (ac) 2-year Composite Runoff Coefficient 10-year Composite Runoff Coefficient 100-year Composite Runoff Coefficient Composite % Imperv. N1* 10975 0.252 0.039 0.000 0.000 0.000 0.000 0.21 0.72 0.72 0.88 86% N2-4 40569 0.931 0.538 0.000 0.383 0.000 0.000 0.01 0.94 0.94 1.00 95% N5* 1822 0.042 0.024 0.000 0.000 0.000 0.000 0.02 0.79 0.79 1.00 71% N8.a 30439 0.699 0.291 0.000 0.408 0.000 0.000 0.00 0.95 0.95 1.00 94% N8.b 58657 1.347 0.575 0.000 0.747 0.000 0.000 0.02 0.94 0.94 1.00 93% Timberline Storage Overland Flow, Time of Concentration: Project: Timeberline Storage Calculations By: Date: Gutter/Swale Flow, Time of Concentration: Tt = L / 60V Tc = Ti + Tt (Equation RO-2) Velocity (Gutter Flow), V = 20·S ½ Velocity (Swale Flow), V = 15·S ½ NOTE: C-value for overland flows over grassy surfaces; C = 0.25 Is Length >500' ? C*Cf (2-yr Cf =1.00) C*Cf (10-yr Cf =1.00) C*Cf (100-yr Cf =1.25) Length, L (ft) Slope, S (%) Ti 2-yr (min) Ti 10-yr (min) Ti 100-yr (min) Length, L (ft) Slope, S (%) Velocity, V (ft/s) Tt (min) Length, L (ft) Timberline Storage Rational Method Equation: Project: Timeberline Storage Calculations By: Date: From Section 3.2.1 of the CFCSDDC Rainfall Intensity: n1 N1* 0.25 12 12 9 0.72 0.72 0.88 2.05 3.50 8.03 1.46 2.49 7.00 n2-4 N2-4 0.93 7 7 5 0.94 0.94 1.00 2.60 4.44 9.95 2.28 3.89 9.27 n5 N5* 0.04 5 5 5 0.79 0.79 1.00 2.85 4.87 9.95 1.24 2.12 5.47 n8.a N8.a 0.70 6 6 5 0.95 0.95 1.00 2.76 4.72 9.95 1.83 3.13 6.95 n8.b N8.b 1.35 5 5 5 0.94 0.94 1.00 2.85 4.87 9.95 3.60 6.15 13.40 n9 N9* 0.96 5 5 5 0.32 0.32 0.40 2.85 4.87 9.95 0.87 1.49 3.81 n10 N10* 2.52 17 17 16 0.80 0.80 1.00 1.75 2.99 6.30 3.53 6.04 15.89 n13 N13* 0.31 5 5 5 0.72 0.72 0.88 2.85 4.87 9.95 2.11 3.60 8.98 Area, A (acres) Intensity, i2 (in/hr) 100-yr Tc (min) DEVELOPED RUNOFF COMPUTATIONS C100 Design Point Flow, Q100 (cfs) Flow, Q2 (cfs) 10-yr Tc (min) 2-yr Tc (min) C2 Flow, Q10 (cfs) Intensity, i100 (in/hr) Basin(s) B. Mathisen September 20, 2016 Intensity, i10 (in/hr) Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1 C10 Q = C f ( C )( i )( A ) Page 3 of 23 D:\Projects\1269-001\Drainage\Hydrology\1269-001_Rational-Calcs9.20.16.xlsx\Direct-Runoff Timberline Storage CHARACTER OF SURFACE: Runoff Coefficient Percentage Impervious Project: Timeberline Storage Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: B. Mathisen Asphalt ……....……………...……….....…...……………….………………………………….. 0.95 100% Date: September 20, 2016 Concrete …….......……………….….……….………………..….………………………………… 0.95 90% Gravel ……….…………………….….…………………………..……………………………….. 0.50 40% Roofs …….…….………………..……………….…………………………………………….. 0.95 90% Pavers…………………………...………………..…………………………………………….. 0.40 22% Lawns and Landscaping Sandy Soil ……..……………..……………….…………………………………………….. 0.15 0% Clayey Soil ….….………….…….…………..………………………………………………. 0.25 0% 2-year Cf = 1.00 100-year Cf = 1.25 Design Point Basin IDs Basin Area (s.f.) Basin Area (ac) Area of Asphalt (ac) Area of Concrete (ac) Area of Roofs (ac) Area of Gravel (ac) Area of Pavers (ac) Area of Lawns and Landscaping (ac) 2-year Composite Runoff Coefficient 10-year Composite Runoff Coefficient 100-year Composite Runoff Coefficient Composite % Imperv. n2 N8.a & N8.b 89096 2.05 0.87 0.00 1.15 0.00 0.00 0.02 0.94 0.94 1.00 93% COMBINED DEVELOPED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS **Soil Classification of site is Sandy Loam** 10-year Cf = 1.00 Runoff Coefficients are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3. % Impervious taken from UDFCD USDCM, Volume I. Page 4 of 23 D:\Projects\1269-001\Drainage\Hydrology\1269-001_Rational-Calcs9.20.16.xlsx\Comb-C-Values Timberline Storage Overland Flow, Time of Concentration: Project: Timeberline Storage Calculations By: Date: Gutter/Swale Flow, Time of Concentration: Tt = L / 60V Tc = Ti + Tt (Equation RO-2) Velocity (Gutter Flow), V = 20·S½ Velocity (Swale Flow), V = 15·S½ NOTE: C-value for overland flows over grassy surfaces; C = 0.25 Is Length >500' ? C*Cf (2-yr Cf=1.00) C*Cf (10-yr Cf=1.00) C*Cf (100-yr Cf=1.25) Length, L (ft) Slope, S (%) Ti 2-yr (min) Ti 10-yr (min) Ti 100-yr (min) Length, L (ft) Slope, S (%) Velocity, V (ft/s) Tt (min) Length, L (ft) Slope, S (%) Velocity, V (ft/s) Tt (min) 2-yr Timberline Storage Rational Method Equation: Project: Timeberline Storage Calculations By: Date: From Section 3.2.1 of the CFCSDDC Rainfall Intensity: n8 N8.a & N8.b 2.05 6 6 5 0.94 0.94 1.00 2.67 4.56 9.95 5.1 8.8 20.4 Intensity, i2 (in/hr) Intensity, i10 (in/hr) Intensity, i100 (in/hr) COMBINED DEVELOPED RUNOFF COMPUTATIONS B. Mathisen September 20, 2016 Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1 Design Point Basin(s) Area, A (acres) 2-yr Tc (min) 10-yr Tc (min) 100-yr Tc (min) Flow, Q2 (cfs) Flow, Q10 (cfs) Flow, Q100 (cfs) C2 C10 C100 Q = C f ( C )( i )( A ) Page 6 of 23 D:\Projects\1269-001\Drainage\Hydrology\1269-001_Rational-Calcs9.20.16.xlsx\Comb-Direct-Runoff Timberline Storage DESIGN POINT BASIN ID TOTAL AREA (acres) C2 C100 2-yr Tc (min) 100-yr Tc (min) Q2 (cfs) Q100 (cfs) n1 N1* 0.25 0.72 0.88 12.0 9.2 1.46 7.00 n2-4 N2-4 0.93 0.94 1.00 6.7 5.0 2.28 9.27 n5 N5* 0.04 0.79 1.00 5.0 5.0 1.24 5.47 n8.a N8.a 0.70 0.95 1.00 6.0 5.0 1.83 6.95 n8.b N8.b 1.35 0.94 1.00 5.2 5.0 3.60 13.40 n9 N9* 0.96 0.32 0.40 5.0 5.0 0.87 3.81 n10 N10* 2.52 0.80 1.00 17.0 16.0 3.53 15.89 n13 N13* 0.31 0.72 0.88 5.0 5.0 2.11 8.98 DESIGN POINT BASIN ID TOTAL AREA (acres) C10 C100 10-yr Tc (min) 100-yr Tc (min) Q10 (cfs) Q100 (cfs) Inlet 8 N8.a & N8.b 2.05 0.94 1.00 6.3 5.0 8.78 20.35 Page 7 of 23 D:\Projects\1269-001\Drainage\Hydrology\1269-001_Rational-Calcs9.20.16.xlsx\SUMMARY-TABLE APPENDIX B HYDRAULIC COMPUTATIONS B.1 – Storm Sewers B.2 – Detention Facilities APPENDIX B.1 STORM SEWERS APPENDIX B.2 INLETS (FOR FUTURE USE) 3130 Verona Avenue • Buford, GA 30518 (866) 888-8479 / (770) 932-2443 • Fax: (770) 932-2490 © Nyloplast Inlet Capacity Charts June 2012 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 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 1.10 Capacity (cfs) Head (ft) Nyloplast 2' x 3' Road & Highway 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 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 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 1.10 Capacity (cfs) Head (ft) Nyloplast 2' x 3' Road & Highway 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 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 1.10 Capacity (cfs) Head (ft) Nyloplast 2' x 2' Road & Highway 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 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 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 1.10 Capacity (cfs) Head (ft) Nyloplast 2' x 3' Road & Highway Grate Inlet Capacity Chart APPENDIX B.3 DETENTION FACILITIES Pond No : 1 100-yr 1.00 5.00 min 4278 ft3 0.93 acres 0.098 ac-ft Max Release Rate = 3.14 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 2779 1.00 3.14 942 1837 10 7.720 4312 0.75 2.36 1413 2899 15 6.520 5463 0.67 2.09 1884 3579 20 5.600 6256 0.63 1.96 2355 3901 25 4.980 6955 0.60 1.88 2826 4129 30 4.520 7575 0.58 1.83 3297 4278 35 4.080 7977 0.57 1.79 3768 4209 40 3.740 8357 0.56 1.77 4239 4118 45 3.460 8697 0.56 1.74 4710 3987 50 3.230 9021 0.55 1.73 5181 3840 55 3.030 9309 0.55 1.71 5652 3657 60 2.860 9586 0.54 1.70 6123 3463 65 2.720 9876 0.54 1.69 6594 3282 70 2.590 10127 0.54 1.68 7065 3062 75 2.480 10390 0.53 1.67 7536 2854 80 2.380 10636 0.53 1.67 8007 2629 85 2.290 10873 0.53 1.66 8478 2395 90 2.210 11111 0.53 1.66 8949 2162 95 2.130 11303 0.53 1.65 9420 1883 100 2.060 11507 0.53 1.65 9891 1616 105 2.000 11731 0.52 1.64 10362 1369 110 1.940 11921 0.52 1.64 10833 1088 115 1.890 12141 0.52 1.64 11304 837 120 1.840 12334 0.52 1.64 11775 559 *Note: Using the method described in Urban Storm Drainage Criteria Manual Volume 2. 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 1269-001 Project: Chamber Model - SC-160 Units - Imperial 100 Number of chambers - 270 Voids in the stone (porosity) - 40 % Base of STONE Elevation - 4906.47 ft Amount of Stone Above Chambers - 6 in Amount of Stone Below Chambers - 6 in Area of system - 5069 sf Min. Area - Height of System Incremental Single Chamber Incremental Total Chamber Incremental Stone Incremental Ch & St Cumulative Chamber Elevation (inches) (cubic feet) (cubic feet) (cubic feet) (cubic feet) (cubic feet) (feet) 24 0.00 0.00 168.97 168.97 5165.48 4908.47 23 0.00 0.00 168.97 168.97 4996.52 4908.39 22 0.00 0.00 168.97 168.97 4827.55 4908.30 21 0.00 0.00 168.97 168.97 4658.58 4908.22 20 0.00 0.00 168.97 168.97 4489.62 4908.14 19 0.00 0.00 168.97 168.97 4320.65 4908.05 18 0.05 13.83 163.44 177.26 4151.68 4907.97 17 0.13 36.29 154.45 190.74 3974.42 4907.89 16 0.29 78.46 137.58 216.04 3783.67 4907.80 15 0.44 119.32 121.24 240.56 3567.63 4907.72 14 0.54 145.57 110.74 256.31 3327.07 4907.64 13 0.62 166.41 102.40 268.81 3070.76 4907.55 12 0.68 183.80 95.45 279.25 2801.95 4907.47 11 0.74 198.69 89.49 288.18 2522.70 4907.39 10 0.78 211.52 84.36 295.88 2234.52 4907.30 9 0.82 222.73 79.88 302.60 1938.65 4907.22 8 0.86 232.29 76.05 308.34 1636.04 4907.14 7 0.89 241.56 72.34 313.90 1327.70 4907.05 6 0.00 0.00 168.97 168.97 1013.80 4906.97 5 0.00 0.00 168.97 168.97 844.83 4906.89 4 0.00 0.00 168.97 168.97 675.87 4906.80 3 0.00 0.00 168.97 168.97 506.90 4906.72 2 0.00 0.00 168.97 168.97 337.93 4906.64 1 0.00 0.00 168.97 168.97 168.97 4906.55 StormTech SC-160 Cumulative Storage Volumes Timberline Storage - Underground Pond N2-4 4003 sf min. area Include Perimeter Stone in Calculations Click Here for Metric 7/15/2016 ADS StormTech Design Tool http://stormtechcalc.azurewebsites.net/ 1/1 User Inputs Chamber Model SC160 Outlet Control Structure Yes (Outlet) Project Name Timberline Storage Project Location Fort Collins, CO Underground Pond (Detention) N24 Project Date 07/13/2016 Engineer B. Mathisen Measurement Type Imperial Required Storage Volume 4,278 cubic ft. Stone Porosity 40% Stone Above Chamber 6 in. Stone Foundation Depth 6 in. Average Cover Over Chambers 14 in. Design Constraint WIDTH Design Constraint Dimension 25 ft. Results System Volume and Bed Size Installed Storage Volume 4280 cubic ft. Storage Volume Per Chamber 15.97 cubic ft. Number Of Chambers Required 268 each Number Of End Caps Required 20 each Rows/Chambers 8 row(s) of 27 chamber(s) Leftover Rows/Chambers 2 row(s) of 26 chamber(s) Maximum Length 198.34 ft. Maximum Width 23.43 ft. Approx. Bed Size Required 4630 square ft. System Components Volume Of Excavation (Not Including Fill) 457 cubic yards Nonwoven Filter Fabric Required 1125 square yards Length Of Isolator Row 194.2 ft. Geogrid NA square yards Woven Isolator Row Fabric 173 square yards © ADS StormTech 2015 Pond No : 1 100-yr 1.00 5.00 min 449 ft3 2.04 acres 0.010 ac-ft Max Release Rate = 20.00 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 6089 1.00 20.00 6000 89 10 7.720 9449 0.75 15.00 9000 449 15 6.520 11971 0.67 13.33 12000 -29 20 5.600 13709 0.63 12.50 15000 -1291 25 4.980 15239 0.60 12.00 18000 -2761 30 4.520 16597 0.58 11.67 21000 -4403 35 4.080 17479 0.57 11.43 24000 -6521 40 3.740 18311 0.56 11.25 27000 -8689 45 3.460 19058 0.56 11.11 30000 -10942 50 3.230 19768 0.55 11.00 33000 -13232 55 3.030 20398 0.55 10.91 36000 -15602 60 2.860 21004 0.54 10.83 39000 -17996 65 2.720 21640 0.54 10.77 42000 -20360 70 2.590 22191 0.54 10.71 45000 -22809 75 2.480 22766 0.53 10.67 48000 -25234 80 2.380 23305 0.53 10.63 51000 -27695 85 2.290 23825 0.53 10.59 54000 -30175 90 2.210 24345 0.53 10.56 57000 -32655 95 2.130 24768 0.53 10.53 60000 -35232 100 2.060 25214 0.53 10.50 63000 -37786 105 2.000 25704 0.52 10.48 66000 -40296 110 1.940 26120 0.52 10.45 69000 -42880 115 1.890 26604 0.52 10.43 72000 -45396 120 1.840 27026 0.52 10.42 75000 -47974 *Note: Using the method described in Urban Storm Drainage Criteria Manual Volume 2. DETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDF Input Variables Results Required Detention Volume Fort Collins, Colorado 1269-001 Timberline Storage Project Number : Project Name : Underground Pond N8.a & N8.b A = Tc = Project: Chamber Model - SC-740 Units - Imperial 100 Number of chambers - 12 Voids in the stone (porosity) - 40 % Base of STONE Elevation - 4905.20 ft Amount of Stone Above Chambers - 6 in Amount of Stone Below Chambers - 6 in Area of system - 738 sf Min. Area - Height of System Incremental Single Chamber Incremental Total Chamber Incremental Stone Incremental Ch & St Cumulative Chamber Elevation (inches) (cubic feet) (cubic feet) (cubic feet) (cubic feet) (cubic feet) (feet) 42 0.00 0.00 24.60 24.60 1364.05 4908.70 41 0.00 0.00 24.60 24.60 1339.45 4908.62 40 0.00 0.00 24.60 24.60 1314.85 4908.53 39 0.00 0.00 24.60 24.60 1290.25 4908.45 38 0.00 0.00 24.60 24.60 1265.65 4908.37 37 0.00 0.00 24.60 24.60 1241.05 4908.28 36 0.05 0.66 24.34 25.00 1216.45 4908.20 35 0.16 1.96 23.82 25.77 1191.45 4908.12 34 0.28 3.38 23.25 26.63 1165.68 4908.03 33 0.60 7.25 21.70 28.95 1139.05 4907.95 32 0.80 9.62 20.75 30.37 1110.10 4907.87 31 0.95 11.41 20.04 31.44 1079.73 4907.78 30 1.07 12.89 19.44 32.34 1048.28 4907.70 29 1.18 14.17 18.93 33.10 1015.94 4907.62 28 1.27 15.19 18.52 33.71 982.85 4907.53 27 1.36 16.26 18.10 34.36 949.13 4907.45 26 1.45 17.45 17.62 35.07 914.78 4907.37 25 1.52 18.30 17.28 35.58 879.71 4907.28 24 1.58 18.99 17.00 35.99 844.13 4907.20 23 1.64 19.71 16.72 36.42 808.14 4907.12 22 1.70 20.39 16.44 36.84 771.71 4907.03 21 1.75 21.04 16.19 37.22 734.88 4906.95 20 1.80 21.63 15.95 37.58 697.65 4906.87 19 1.85 22.26 15.70 37.96 660.07 4906.78 18 1.89 22.72 15.51 38.23 622.12 4906.70 17 1.93 23.21 15.32 38.52 583.89 4906.62 16 1.97 23.70 15.12 38.82 545.36 4906.53 15 2.01 24.12 14.95 39.07 506.54 4906.45 14 2.04 24.54 14.78 39.32 467.47 4906.37 13 2.07 24.90 14.64 39.54 428.15 4906.28 12 2.10 25.26 14.50 39.76 388.61 4906.20 11 2.13 25.58 14.37 39.95 348.85 4906.12 10 2.15 25.85 14.26 40.11 308.90 4906.03 9 2.18 26.12 14.15 40.27 268.80 4905.95 8 2.20 26.38 14.05 40.43 228.52 4905.87 7 2.21 26.49 14.00 40.49 188.09 4905.78 6 0.00 0.00 24.60 24.60 147.60 4905.70 5 0.00 0.00 24.60 24.60 123.00 4905.62 4 0.00 0.00 24.60 24.60 98.40 4905.53 Project: Chamber Model - SC-740 Units - Imperial 100 Number of chambers - 23 Voids in the stone (porosity) - 40 % Base of STONE Elevation - 4905.03 ft Amount of Stone Above Chambers - 6 in Amount of Stone Below Chambers - 6 in Area of system - 1238 sf Min. Area - Height of System Incremental Single Chamber Incremental Total Chamber Incremental Stone Incremental Ch & St Cumulative Chamber Elevation (inches) (cubic feet) (cubic feet) (cubic feet) (cubic feet) (cubic feet) (feet) 42 0.00 0.00 41.27 41.27 2367.32 4908.53 41 0.00 0.00 41.27 41.27 2326.05 4908.45 40 0.00 0.00 41.27 41.27 2284.79 4908.36 39 0.00 0.00 41.27 41.27 2243.52 4908.28 38 0.00 0.00 41.27 41.27 2202.25 4908.20 37 0.00 0.00 41.27 41.27 2160.99 4908.11 36 0.05 1.26 40.76 42.03 2119.72 4908.03 35 0.16 3.75 39.77 43.51 2077.70 4907.95 34 0.28 6.48 38.67 45.16 2034.18 4907.86 33 0.60 13.89 35.71 49.60 1989.02 4907.78 32 0.80 18.44 33.89 52.33 1939.42 4907.70 31 0.95 21.87 32.52 54.39 1887.09 4907.61 30 1.07 24.71 31.38 56.09 1832.71 4907.53 29 1.18 27.15 30.41 57.56 1776.61 4907.45 28 1.27 29.11 29.62 58.73 1719.05 4907.36 27 1.36 31.17 28.80 59.97 1660.32 4907.28 26 1.45 33.44 27.89 61.33 1600.36 4907.20 25 1.52 35.07 27.24 62.31 1539.02 4907.11 24 1.58 36.39 26.71 63.10 1476.71 4907.03 23 1.64 37.77 26.16 63.93 1413.61 4906.95 22 1.70 39.09 25.63 64.72 1349.68 4906.86 21 1.75 40.32 25.14 65.46 1284.96 4906.78 20 1.80 41.46 24.68 66.15 1219.50 4906.70 19 1.85 42.66 24.20 66.87 1153.36 4906.61 18 1.89 43.54 23.85 67.39 1086.49 4906.53 17 1.93 44.48 23.47 67.96 1019.10 4906.45 16 1.97 45.42 23.10 68.52 951.15 4906.36 15 2.01 46.23 22.78 69.00 882.62 4906.28 14 2.04 47.03 22.45 69.49 813.62 4906.20 13 2.07 47.72 22.18 69.90 744.13 4906.11 12 2.10 48.41 21.90 70.31 674.23 4906.03 11 2.13 49.03 21.65 70.69 603.92 4905.95 10 2.15 49.54 21.45 70.99 533.23 4905.86 9 2.18 50.07 21.24 71.31 462.24 4905.78 8 2.20 50.56 21.04 71.60 390.93 4905.70 7 2.21 50.77 20.96 71.73 319.33 4905.61 6 0.00 0.00 41.27 41.27 247.60 4905.53 5 0.00 0.00 41.27 41.27 206.33 4905.45 4 0.00 0.00 41.27 41.27 165.07 4905.36 N2-4 N1 N5 N13 GRAPHIC SCALE: LEGEND: SUMMARY: ( IN FEET ) 0 1 INCH = 60 FEET 60 60 120 180 NORTH OFF-SITE DRAINAGE AREA COMPARISON FORT COLLINS, CO TIMBERLINE STORAGE E NGINEER ING N O R T H E RN 07.20.2016 D:\PROJECTS\1269-001\DWG\ENGINEER\MATHISEN\DRAINAGE\1269-001_DRNG_EXHIBIT.DWG N2-4 1621.66 sq. ft. Date: 7/15/2016 Calculated By: B. Mathisen Northern No. 1269-001 Basin ID Historic Area [ac] New Area [ac] Net Change in Area [ac] C100 tc [min] Q100 [cfs] 8 1.46 2.05 +0.59 1.00 5.0 20.4 9 1.17 0.93 -0.24 1.0* 5.0* 9.58 10 2.52 2.52 0.00 1.0* 12.9* 17.71* *Info Per Spring Creek Center Drainage Report Basin Comparison Historic vs. Proposed APPENDIX C WATER QUALITY DESIGN COMPUTATIONS 1008 Project Title Date: Project Number Calcs By: Client Basins 0.8 WQCV = Watershed inches of Runoff (inches) 95.00% a = Runoff Volume Reduction (constant) i = Total imperviousness Ratio (i = Iwq /100) 0.358 in A = 0.93 ac V = 0.0278 ac-ft V = Water Quality Design Volume (ac-ft) WQCV = Water Quality Capture Volume (inches) A = Watershed Area (acres) Timberline Self-Storage September 19, 2016 1269-001 B. Mathisen Basin N2-4 1209 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 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 WQCV (watershed inches) Total Imperviousness Ratio (i = Iwq /100) Water Quality Capture Volume 6 hr 12 hr 24 hr 40 hr WQCV = a ( 0.91 i 3 − 1 . 19 i 2 + 0 . 78 i ) WQCV = a ( 0.91 i 3 − 1 . 19 i 2 + 0 . 78 i ) V * A 12 WQCV Pond No : Basin N2-4 WQ 0.94 7.00 min 310 ft3 0.93 acres 0.01 ac-ft Max Release Rate = 0.66 cfs Time (min) Ft Collins WQ Intensity (in/hr) Inflow Volume (ft3) Outflow Adjustment Factor Qav (cfs) Outflow Volume (ft3) Storage Volume (ft3) 5 1.425 374 1.00 0.66 198 176 10 1.105 580 1.00 0.66 396 184 15 0.935 736 0.73 0.48 436 301 20 0.805 845 0.68 0.45 535 310 25 0.715 939 0.64 0.42 634 305 30 0.650 1024 0.62 0.41 733 291 35 0.585 1075 0.60 0.40 832 243 40 0.535 1124 0.59 0.39 931 193 45 0.495 1170 0.58 0.38 1030 139 50 0.460 1208 0.57 0.38 1129 78 55 0.435 1256 0.56 0.37 1228 28 60 0.410 1292 0.56 0.37 1327 -36 65 0.385 1314 0.55 0.37 1426 -112 70 0.365 1342 0.55 0.36 1526 -184 75 0.345 1359 0.55 0.36 1625 -266 80 0.330 1386 0.54 0.36 1724 -337 85 0.315 1406 0.54 0.36 1823 -417 90 0.305 1441 0.54 0.36 1922 -480 95 0.290 1447 0.54 0.35 2021 -574 100 0.280 1470 0.54 0.35 2120 -650 105 0.270 1489 0.53 0.35 2219 -730 110 0.260 1502 0.53 0.35 2318 -816 115 0.255 1540 0.53 0.35 2417 -877 120 0.245 1544 0.53 0.35 2516 -972 *Note: Using the method described in Urban Storm Drainage Criteria Manual Volume 2. DETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDF Input Variables Results Required Detention Volume Fort Collins, Colorado 1269-001 Timberline Self-Storage Project Number : Project Name : Basin N2-4 Vault ID Total Required WQ Volume (cf) Flow, WQ (cfs) Chamber Type Chamber Release Ratea (cfs) Chamber Volumeb (cf) Installed Camber w/ Aggregatec (cf) Mimimum No. of Chambersd Total Release Ratee (cfs) Required Storage Volume by FAA Method (cf) Mimimum No. of Chambersf Storage Provided within the Chambersg (cf) Total Installed System Volumeh (cf) Basin N2-4 1209 1.14 SC-160 0.016 14.70 29.30 42 0.66 310 22 323 1231 SC-740 a. 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 Summary D:\Projects\1269-001\Drainage\WatQual\Basin N2-4 WQ Chambers.xlsx Project Tittle Date: Project Number Calcs By: Client Pond Designation Q = 3.14 cfs C = 0.604 Q = Release Rate (cfs) Eh = 4908.47 ft C = Discharge Coefficients (unitless) Ei = 4906.22 ft Aa = Area Allowed of Opening (ft2) g = Gravity (32.2 ft/s2) 0.431588 ft2 Eh = High Water Surface Elevation (ft) 62.14865 in2 Ei = Elevation of Outlet Invert (ft) H = Height of Opening (in.) R = Inner Radius of Outfall Pipe (in.) Δ = Top of Plate to Center of Pipe (in.) S = Arc Length of Open Area (in.) Ac = Area of Opening (in2) θ = Angle of Plate on Pipe to Center Pipe (radians) 6-3/8 in 12 in Bradon Grebe 1269-001 Timberline Storage Underground Pond N2-4 Calculated Area of Opening (Ac) Design Hieght of Opening (H) Proposed Pipe Diameter 61.05 sq. in. B. Mathisen September 16th, 2016 Aa = [ ( ( ) ) ] 2 2 R Sin S R R S K − = Q = CA 2 g ( E h − E i ) S = R θ ( ) ( R ) Cos R Cos → = ∆ = ∆ 2 −1 θ 2 θ Ac = π R 2 − K Project Tittle Date: Project Number Calcs By: Client Pond Designation Q = Flow Rate (CFS) C = Ratio of Actual Discharge to Theoretical Discharge L = Crest Length (ft) H = Height of Flow Above Crest (ft) P = Vertical Distrance from Weir Crest to Pond/Channel Invert (ft) Flow (Q100) Length (L) Crest Elevation Upstream Invert Elevation H Elevation H/(H+P) Flow 0 4908.47 0 0.865 0 Invalid 0.1 4908.57 0.047641734 0.858 1.415018 Invalid 0.3 4908.77 0.130491518 0.857 3.21862 Valid 100-yr Q 0.3 4908.77 0.130491518 0.857 3.21862 Valid 0.4 4908.87 0.16673614 0.859 4.00257 Valid 0.5 4908.97 0.200080032 0.861 4.746948 Valid 0.6 4909.07 0.230858022 0.865 5.462758 Valid 0.7 4909.17 0.259355317 0.868 6.156398 Valid 0.8 4909.27 0.285816363 0.871 6.831961 Valid 0.9 4909.37 0.31045188 0.875 7.492277 Valid 1 4909.47 0.333444481 0.878 8.139445 Valid Timberline Storage September 16th, 2016 1269-001 B. Mathisen Bradon Grebe Q = 3.22 cfs is achieved at hieght of 0.291 feet Valid if 0.1<H/L>0.8 3.00 ft Depth vs. Flow C Check H/L Reference: "Hydraulic Engineering, Roberson, Cassidy & Chaudhry., Jogn Wiley & Sons, 1995, pg. 212" 4906.47 ft 4908.47 ft 3.14 cfs Underground Pond N2-4 0.857 0.8 0.9 1 1.1 1.2 1.3 1.4 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 C H/(H+P) 1008 Project Title Date: Project Number Calcs By: Client Basins 0.8 WQCV = Watershed inches of Runoff (inches) 94.00% a = Runoff Volume Reduction (constant) i = Total imperviousness Ratio (i = Iwq /100) 0.350 in A = 0.70 ac V = 0.0204 ac-ft V = Water Quality Design Volume (ac-ft) WQCV = Water Quality Capture Volume (inches) A = Watershed Area (acres) 888 cu. ft. Drain Time a = i = WQCV = Figure EDB-2 - Water Quality Capture Volume (WQCV), 80th Percentile Runoff Event Timberline Self-Storage September 19, 2016 1269-001 B. Mathisen Basin N8.a 0.231 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 WQCV (watershed inches) Total Imperviousness Ratio (i = Iwq /100) Water Quality Capture Volume 6 hr 12 hr 24 hr 40 hr WQCV = a ( 0.91 i 3 − 1 . 19 i 2 + 0 . 78 i ) WQCV = a ( 0.91 i 3 − 1 . 19 i 2 + 0 . 78 i ) V * A 12 WQCV Pond No : Basin 8 WQ 0.95 5.00 min 480 ft3 0.70 acres 0.01 ac-ft Max Release Rate = 0.28 cfs Time (min) Ft Collins WQ Intensity (in/hr) Inflow Volume (ft3) Outflow Adjustment Factor Qav (cfs) Outflow Volume (ft3) Storage Volume (ft3) 5 1.425 284 1.00 0.28 85 199 10 1.105 440 1.00 0.28 170 270 15 0.935 559 0.67 0.19 170 389 20 0.805 641 0.63 0.18 212 429 25 0.715 712 0.60 0.17 255 457 30 0.650 777 0.58 0.17 297 480 35 0.585 816 0.57 0.16 340 476 40 0.535 853 0.56 0.16 382 471 45 0.495 888 0.56 0.16 425 463 50 0.460 916 0.55 0.16 467 449 55 0.435 953 0.55 0.15 509 444 60 0.410 980 0.54 0.15 552 428 65 0.385 997 0.54 0.15 594 403 70 0.365 1018 0.54 0.15 637 381 75 0.345 1031 0.53 0.15 679 352 80 0.330 1052 0.53 0.15 722 330 85 0.315 1067 0.53 0.15 764 303 90 0.305 1094 0.53 0.15 807 287 95 0.290 1098 0.53 0.15 849 249 100 0.280 1116 0.53 0.15 892 224 105 0.270 1130 0.52 0.15 934 196 110 0.260 1140 0.52 0.15 976 163 115 0.255 1168 0.52 0.15 1019 149 120 0.245 1171 0.52 0.15 1061 110 *Note: Using the method described in Urban Storm Drainage Criteria Manual Volume 2. 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 Vault ID Total Required WQ Volume (cf) Flow, WQ (cfs) Chamber Type Chamber Release Ratea (cfs) Chamber Volumeb (cf) Installed Camber w/ Aggregatec (cf) Mimimum No. of Chambersd Total Release Ratee (cfs) Required Storage Volume by FAA Method (cf) Mimimum No. of Chambersf Storage Provided within the Chambersg (cf) Total Installed System Volumeh (cf) Basin N8.a 888 0.92 SC-740 0.024 45.90 74.90 12 0.28 480 11 505 899 SC-740 a. 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 Summary D:\Projects\1269-001\Drainage\WatQual\Basin N8.a WQ Chambers.xlsx 1008 Project Title Date: Project Number Calcs By: Client Basins 0.8 WQCV = Watershed inches of Runoff (inches) 93.00% a = Runoff Volume Reduction (constant) i = Total imperviousness Ratio (i = Iwq /100) 0.343 in A = 1.35 ac V = 0.0384 ac-ft V = Water Quality Design Volume (ac-ft) WQCV = Water Quality Capture Volume (inches) A = Watershed Area (acres) Timberline Self-Storage September 19, 2016 1269-001 B. Mathisen Basin N8.b 1675 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 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 WQCV (watershed inches) Total Imperviousness Ratio (i = Iwq /100) Water Quality Capture Volume 6 hr 12 hr 24 hr 40 hr WQCV = a ( 0.91 i 3 − 1 . 19 i 2 + 0 . 78 i ) WQCV = a ( 0.91 i 3 − 1 . 19 i 2 + 0 . 78 i ) V * A 12 WQCV Pond No : Basin 8 WQ 0.94 5.00 min 912 ft3 1.35 acres 0.02 ac-ft Max Release Rate = 0.54 cfs Time (min) Ft Collins WQ Intensity (in/hr) Inflow Volume (ft3) Outflow Adjustment Factor Qav (cfs) Outflow Volume (ft3) Storage Volume (ft3) 5 1.425 541 1.00 0.54 163 379 10 1.105 839 1.00 0.54 325 514 15 0.935 1065 0.67 0.36 325 740 20 0.805 1223 0.63 0.34 407 816 25 0.715 1358 0.60 0.33 488 870 30 0.650 1481 0.58 0.32 570 912 35 0.585 1556 0.57 0.31 651 905 40 0.535 1626 0.56 0.31 732 893 45 0.495 1692 0.56 0.30 814 879 50 0.460 1747 0.55 0.30 895 852 55 0.435 1818 0.55 0.30 976 841 60 0.410 1869 0.54 0.29 1058 811 65 0.385 1901 0.54 0.29 1139 762 70 0.365 1941 0.54 0.29 1221 720 75 0.345 1966 0.53 0.29 1302 664 80 0.330 2006 0.53 0.29 1383 622 85 0.315 2034 0.53 0.29 1465 569 90 0.305 2085 0.53 0.29 1546 539 95 0.290 2093 0.53 0.29 1627 466 100 0.280 2127 0.53 0.28 1709 418 105 0.270 2154 0.52 0.28 1790 364 110 0.260 2173 0.52 0.28 1872 301 115 0.255 2228 0.52 0.28 1953 275 120 0.245 2234 0.52 0.28 2034 199 *Note: Using the method described in Urban Storm Drainage Criteria Manual Volume 2. DETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDF Input Variables Results Required Detention Volume Fort Collins, Colorado 1269-001 Timberline Self-Storage Project Number : Project Name : Basin N8.b Vault ID Total Required WQ Volume (cf) Flow, WQ (cfs) Chamber Type Chamber Release Ratea (cfs) Chamber Volumeb (cf) Installed Camber w/ Aggregatec (cf) Mimimum No. of Chambersd Total Release Ratee (cfs) Required Storage Volume by FAA Method (cf) Mimimum No. of Chambersf Storage Provided within the Chambersg (cf) Total Installed System Volumeh (cf) Basin 8 1675 1.80 SC-740 0.024 45.90 74.90 23 0.54 912 20 918 1723 SC-740 a. 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 Summary D:\Projects\1269-001\Drainage\WatQual\Basin N8.b WQ Chambers.xlsx Project Tittle Date: Project Number Calcs By: Client Pond Designation Q = Flow Rate (CFS) C = Ratio of Actual Discharge to Theoretical Discharge L = Crest Length (ft) H = Height of Flow Above Crest (ft) P = Vertical Distrance from Weir Crest to Pond/Channel Invert (ft) Flow (Q100) Length (L) Crest Elevation Upstream Invert Elevation H Elevation H/(H+P) Flow 0 4910.64 0 0.865 0 Invalid 0.1 4910.74 0.027578599 0.861 1.891495 Invalid 0.2 4910.84 0.053676865 0.858 3.171158 Invalid 0.3 4910.94 0.078410873 0.857 4.291214 Invalid 0.4 4911.04 0.10188487 0.856 5.321914 Valid 0.5 4911.14 0.124192747 0.856 6.293583 Valid 0.6 4911.24 0.145419292 0.857 7.22269 Valid 0.7 4911.34 0.165641268 0.858 8.119288 Valid 0.8 4911.44 0.18492834 0.86 8.989978 Valid 0.9 4911.54 0.203343877 0.862 9.839323 Valid 1 4911.64 0.220945647 0.863 10.67061 Valid Reference: "Hydraulic Engineering, Roberson, Cassidy & Chaudhry., Jogn Wiley & Sons, 1995, pg. 212" 4907.11 ft 4910.64 ft 20.00 cfs Underground Pond N8.a & N8.b Q = 16.88 cfs is achieved at hieght of 1.723 feet Valid if 0.1<H/L>0.8 4.00 ft Depth vs. Flow C Check H/L Timberline Storage September 16th, 2016 1269-001 B. Mathisen Brandon Grebe 0.879 0.8 0.9 1 1.1 1.2 1.3 1.4 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 C H/(H+P) UD UD UD UD G AS GAS ST LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOD LOT 1 SPRING CREEK CENTER P.U.D. LOT 2 SPRING CREEK CENTER P.U.D. LOT 3 SPRING CREEK LOT 4 CENTER P.U.D. SPRING CREEK CENTER P.U.D. SPECHT POINT ROAD (60' ROW) MIDPOINT DRIVE (60' ROW) LOT 5 SPRING CREEK CENTER P.U.D. LOT 1 20,418 SQ. FT. 0.469 AC APPENDIX D EROSION CONTROL REPORT Timberline Storage Final Erosion Control Report A the comprehensive PDP construction Erosion drawings. and Sediment It should Control be noted, Plan however, (along with that associated any such details) Erosion is and included Sediment with Control depicted, Plan and serves additional only as or different a general BMPs guide from to the those Contractor. included Staging may be and/necessary or phasing during of the BMPs construction, or as required by the authorities having jurisdiction. It maintained shall be the and responsibility followed. The of the Erosion Contractor and Sediment to ensure Control erosion Plan control is intended measures to be are a properly living document, location of BMPs constantly as they adapting are installed, to site conditions removed or and modified needs. in The conjunction Contractor with shall construction update the activities. It is imperative to appropriately reflect the current site conditions at all times. The during Erosion construction, and Sediment as well Control as permanent Plan shall erosion address control both protection. temporary measures Best Management to be implemented Practices from not limited the Volume to, silt 3, fencing Chapter along 7 – the Construction disturbed perimeter, BMPs will gutter be utilized. protection Measures in the may adjacent include, roadways but are and clean-inlet up procedures, protection at designated proposed storm concrete inlets. washout Vehicle areas, tracking dumpsters, control and pads, job spill site containment restrooms shall and also be provided by the Contractor. Grading Plans at and final Erosion design will Control also Notes contain can a be full-found size Erosion on Sheet Control CS2 of Plan the as Utility well Plans. as a separate The Utility sheet dedicated Contractor to shall Erosion be aware Control of, Details. and adhere In addition to, the applicable to this report requirements and the referenced outlined in plan any sheets, existing the Development to issuance of Agreement(the Development s) of record, Construction as well Permit. as the Development Also, the Site Agreement, Contractor to for be this recorded project prior will be Public required Health to and secure Environment a Stormwater (CDPHE)Construction , Water General Quality Control Permit Division from the – Colorado Stormwater Department Program, of before shall develop commencing a comprehensive any earth disturbing StormWater activities. Management Prior to Plan securing (SWMP) said pursuant permit, to the CDPHE Site Contractor requirements inspections, and and maintenance guidelines. The of construction SWMP will BMPs. further describe and document the ongoing activities, APPENDIX E Soils Resource Report 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 Natural Area, Colorado Resources Conservation Service May 19, 2016 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 (http:// 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 alternative means 2 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 How Soil Surveys Are Made..................................................................................5 Soil Map..................................................................................................................7 Soil Map................................................................................................................8 Legend..................................................................................................................9 Map Unit Legend................................................................................................10 Map Unit Descriptions........................................................................................10 Larimer County Area, Colorado......................................................................12 22—Caruso clay loam, 0 to 1 percent slope...............................................12 64—Loveland clay loam, 0 to 1 percent slopes...........................................13 References............................................................................................................15 4 How Soil Surveys Are Made Soil surveys are made to provide information about the soils and miscellaneous areas in a specific area. They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, and shape of the slopes; the general pattern of drainage; the kinds of crops and native plants; and the kinds of bedrock. They observed and described many soil profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The profile extends from the surface down into the unconsolidated material in which the soil formed or from the surface down to bedrock. The unconsolidated material is devoid of roots and other living organisms and has not been changed by other biological activity. Currently, soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAs are geographically associated land resource units that share common characteristics related to physiography, geology, climate, water resources, soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically consist of parts of one or more MLRA. The soils and miscellaneous areas in a survey area occur in an orderly pattern that is related to the geology, landforms, relief, climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform. By observing the soils and miscellaneous areas in the survey area and relating their position to specific segments of the landform, a soil scientist develops a concept, or model, of how they were formed. Thus, during mapping, this model enables the soil scientist to predict with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape. Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soil map, however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations, supplemented by an understanding of the soil-vegetation-landscape relationship, are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries. Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color, texture, size and shape of soil aggregates, kind and amount of rock fragments, distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to taxonomic classes (units). Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States, is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil scientists classified and named the soils in the survey area, they compared the 5 individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research. The objective of soil mapping is not to delineate pure map unit components; the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of soil components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such landforms and landform segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, onsite investigation is needed to define and locate the soils and miscellaneous areas. Soil scientists make many field observations in the process of producing a soil map. The frequency of observation is dependent upon several factors, including scale of mapping, intensity of mapping, design of map units, complexity of the landscape, and experience of the soil scientist. Observations are made to test and refine the soil- landscape model and predictions and to verify the classification of the soils at specific locations. Once the soil-landscape model is refined, a significantly smaller number of measurements of individual soil properties are made and recorded. These measurements may include field measurements, such as those for color, depth to bedrock, and texture, and laboratory measurements, such as those for content of sand, silt, clay, salt, and other components. Properties of each soil typically vary from one point to another across the landscape. Observations for map unit components are aggregated to develop ranges of characteristics for the components. The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties. While a soil survey is in progress, samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Soil scientists interpret the data from these analyses and tests as well as the field-observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils are field tested through observation of the soils in different uses and under different levels of management. Some interpretations are modified to fit local conditions, and some new interpretations are developed to meet local needs. Data are assembled from other sources, such as research information, production records, and field experience of specialists. For example, data on crop yields under defined levels of management are assembled from farm records and from field or plot experiments on the same kinds of soil. Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over long periods of time, but they are not predictable from year to year. For example, soil scientists can predict with a fairly high degree of accuracy that a given soil will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the soil on a specific date. After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and identified each as a specific map unit. Aerial photographs show trees, buildings, fields, roads, and rivers, all of which help in locating boundaries accurately. Custom Soil Resource Report 6 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. 7 8 Custom Soil Resource Report Soil Map 4490530 4490550 4490570 4490590 4490610 4490630 4490650 4490530 4490550 4490570 4490590 4490610 4490630 4490650 496780 496800 496820 496840 496860 496880 496900 496920 496940 496960 496980 496780 496800 496820 496840 496860 496880 496900 496920 496940 496960 496980 40° 34' 0'' N 105° 2' 17'' W 40° 34' 0'' N 105° 2' 7'' W 40° 33' 55'' N 105° 2' 17'' W 40° 33' 55'' N 105° 2' 7'' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 45 90 180 270 Feet 0 15 30 60 90 Meters Map Scale: 1:1,020 if printed on A landscape (11" x 8.5") sheet. 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: http://websoilsurvey.nrcs.usda.gov 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 Map Unit Legend Larimer County Area, Colorado (CO644) Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 22 Caruso clay loam, 0 to 1 percent slope 4.0 97.4% 64 Loveland clay loam, 0 to 1 percent slopes 0.1 2.6% Totals for Area of Interest 4.1 100.0% 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 Custom Soil Resource Report 10 intensive use of small areas is planned, however, 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 11 Larimer County Area, Colorado 22—Caruso clay loam, 0 to 1 percent slope Map Unit Setting National map unit symbol: jpvt Elevation: 4,800 to 5,500 feet Mean annual precipitation: 13 to 15 inches Mean annual air temperature: 48 to 50 degrees F Frost-free period: 135 to 150 days Farmland classification: Prime farmland if irrigated Map Unit Composition Caruso and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Caruso Setting Landform: Flood-plain steps, stream terraces Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Parent material: Mixed alluvium Typical profile H1 - 0 to 35 inches: clay loam H2 - 35 to 44 inches: fine sandy loam, sandy loam H2 - 35 to 44 inches: sand, gravelly sand H3 - 44 to 60 inches: H3 - 44 to 60 inches: Properties and qualities Slope: 0 to 1 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Somewhat poorly drained Runoff class: High 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: About 24 to 48 inches Frequency of flooding: Occasional Frequency of ponding: None Calcium carbonate, maximum in profile: 5 percent Salinity, maximum in profile: Nonsaline to very slightly saline (0.0 to 2.0 mmhos/cm) Available water storage in profile: High (about 9.8 inches) Interpretive groups Land capability classification (irrigated): 3w Land capability classification (nonirrigated): 5w Hydrologic Soil Group: D Minor Components Loveland Percent of map unit: 9 percent Custom Soil Resource Report 12 Landform: Terraces Fluvaquents Percent of map unit: 6 percent Landform: Terraces 64—Loveland clay loam, 0 to 1 percent slopes Map Unit Setting National map unit symbol: jpx9 Elevation: 4,800 to 5,500 feet Mean annual precipitation: 13 to 15 inches Mean annual air temperature: 48 to 50 degrees F Frost-free period: 135 to 150 days Farmland classification: Prime farmland if irrigated Map Unit Composition Loveland and similar soils: 90 percent Minor components: 10 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Loveland Setting Landform: Flood plains, stream terraces Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Parent material: Alluvium Typical profile H1 - 0 to 15 inches: clay loam H2 - 15 to 32 inches: clay loam, silty clay loam, loam H2 - 15 to 32 inches: very gravelly sand, gravelly sand, gravelly coarse sand H2 - 15 to 32 inches: H3 - 32 to 60 inches: H3 - 32 to 60 inches: H3 - 32 to 60 inches: Properties and qualities Slope: 0 to 1 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Poorly drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat): Moderately high (0.20 to 0.60 in/hr) Depth to water table: About 18 to 36 inches Frequency of flooding: Occasional Frequency of ponding: None Calcium carbonate, maximum in profile: 15 percent Custom Soil Resource Report 13 Salinity, maximum in profile: Very slightly saline to slightly saline (2.0 to 4.0 mmhos/ cm) Available water storage in profile: Very high (about 16.7 inches) Interpretive groups Land capability classification (irrigated): 3w Land capability classification (nonirrigated): 3w Hydrologic Soil Group: C Minor Components Poudre Percent of map unit: 5 percent Aquolls Percent of map unit: 5 percent Landform: Swales Custom Soil Resource Report 14 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 15 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 16 MAP POCKET HISTORIC DRAINAGE EXHIBIT PROPOSED DRAINAGE EXHIBIT GAS GAS H Y D S S S h2o h2o h2o h2o H Y D S S SS SS SS SS SS SS SS SS SS SS SS SS SS SS SS SS SS SS SS SS SS V AULT ELEC VAULT ELEC ELEC S ST W W W W W W W W W W W W W S E E E E E E E E E E E E E E E E E UD UD UD UD W S W UD UD 268 STORMTECH SC-160 CHAMBERS 35 STORMTECH SC-740 CHAMBERS n8.b n8.a n2-4 9 10 FLOW CONTROL MANHOLE FLOW CONTROL MANHOLE EMERGENCY OVERFLOW PATH EXISTING INLET 9 EXISTING INLET 10 ISOLATOR ROWS EXISTING SIDEWALK CHASE CONCRETE CHASE 2 ISOLATOR ROWS INLET n8.a INLET n8.b INLET n2-4 INLET 8 SPRING CREEK CENTER P.U.D DEVELOPMENT FUTURE FFE=14.85 LOT 1 SPRING CREEK CENTER P.U.D. LOT 2 SPRING CREEK CENTER P.U.D. LOT 3 SPRING CREEK CENTER P.U.D. LOT 4 SPRING CREEK CENTER P.U.D. SPECHT POINT ROAD (60' ROW) MIDPOINT DRIVE (60' ROW) LOT 5 SPRING CREEK CENTER P.U.D. LOT 1 20,418 SQ. FT. 0.469 AC LOT 2 189,543 SQ. FT. 4.351 AC 10.00 HP 10.60 HP N8.b N10 N2-4 N1 N9 N8.a N5 N13 11 8:1 7:1 11:1 18:1 173:1 55:1 26:1 20:1 39:1 68:1 4:1 10:1 5:1 WQ WEIR BASIN EXISTING STORMCEPTOR CALL UTILITY NOTIFICATION CENTER OF COLORADO Know what'sbelow. Call before you dig. R NOTES: City Engineer Date Date Date Date Date Stormwater Utility Parks & Recreation Traffic Engineer Date Water & Wastewater Utility City of Fort Collins, Colorado UTILITY PLAN APPROVAL Environmental Planner C7.00 DRAINAGE EXHIBIT GRAPHIC SCALE: LEGEND: A2 a3 4950 4:1 79.45 HP RUNOFF SUMMARY TABLE: ( IN FEET ) 0 1 INCH = 40 FEET 40 40 80 120 NORTH Sheet of 19 TIMBERLINE STORAGE These drawings are instruments of service provided by Northern Engineering Services, Inc. and are not to be used for any type of construction unless signed and sealed by a Professional Engineer in the employ of Northern Engineering Services, Inc. NOT FOR CONSTRUCTION REVIEW SET 301 North Howes Street, Suite 100 Fort Collins, Colorado 80521 E NGINEER ING N O R T H E RN PHONE: 970.221.4158 www.northernengineering.com DESIGN POINT BASIN ID TOTAL AREA (acres) C2 C100 2-yr Tc (min) 100-yr Tc (min) Q2 (cfs) Q100 (cfs) n2-4 N2-4 0.93 0.94 1.00 6.7 5.0 2.28 9.27 n8.a N8.a 0.70 0.95 1.00 6.0 5.0 1.83 6.95 n8.b N8.b 1.35 0.94 1.00 5.2 5.0 3.60 13.40 n9 N9* 0.96 0.76 0.95 5.0 5.0 2.09 9.11 n10 N10* 2.52 0.80 1.00 16.0 12.9 3.65 17.76 n10 11* 0.25 0.82 1.00 5.0 5.0 0.58 2.49 17 the version date(s) listed below. Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 10, Sep 22, 2015 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Apr 22, 2011—Apr 28, 2011 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 9 LOT 2 189,543 SQ. FT. 4.351 AC UNDERGROUND POND N8.b UNDERGROUND POND N8.a UNDERGROUND POND N2-4 STORMCEPTOR INLET n2-4 INLET n8.a INLET n8.b INLET 10 INLET 9 N8.b N10 N2-4 N1 N9 N8.a N5 N13 11 INLET 8 LID EXHIBIT FORT COLLINS, CO TIMBERLINE STORAGE E NGINEER ING N O R T H E RN 09.21.2016 D:\PROJECTS\1269-001\DWG\EXHIBITS\1269-001_LID EXHIBIT.DWG NORTH ( IN FEET ) 0 1 INCH = 60 FEET 60 60 120 180 LEGEND GRASS BUFFER STORMTECH CHAMBERS NOTES 1. HATCHING REPRESENTS THE FORM OF LID TREATMENT THAT THAT AREA IS RECEIVING 2. SEE FINAL DRAINAGE REPORT FOR TIMBERLING STORAGE DATED SEPTEMBER 21,2016 FOR ADDITIONAL INFORMATION REGARDING LID AND WATER QUALITY TREATMENT 3. 100% OF THE SITE IS RECEIVING WATER QUALITY VIA STORMCEPTOR OR STORMTECH CHAMBERS. 4. 93% OF THE PROJECT AREA THAT IS WITHIN THE LIMITS OF DISTURBANCE IS BEING TREATED VIA A LID SYSTEM. *ORIGINAL PLOT SIZE 11" x 17" Broad-Crested Weir Coefficient (C) 2 3 Q = 0 . 385 CL 2 gH 1 . 5152 ( ) 2 .1061( ) 1 . 2288 ( ) 0 .1926( ) 0 .8651 4 3 2 + + + − + + + − = H P H H P H H P H H P C H Run A = Tc = Project Location : Design Point C = Design Storm Page 2 of 5 Basin N8.b WQ Chambers.xlsx = 12 hr Fort Collins, Colorado 1269-001 Timberline Self-Storage Project Number : Project Name : Basin N8.a Page 2 of 5 Basin N8.a WQ Chambers.xlsx = 12 hr Broad-Crested Weir Coefficient (C) 2 3 Q = 0 . 385 CL 2 gH 1 . 5152 ( ) 2 .1061( ) 1 . 2288 ( ) 0 .1926( ) 0 .8651 4 3 2 + + + − + + + − = H P H H P H H P H H P C H Run A = Tc = Project Location : Design Point C = Design Storm Page 2 of 5 Basin N2-4 WQ Chambers.xlsx = 12 hr 3 0.00 0.00 41.27 41.27 123.80 4905.28 2 0.00 0.00 41.27 41.27 82.53 4905.20 1 0.00 0.00 41.27 41.27 41.27 4905.11 StormTech SC-740 Cumulative Storage Volumes Timberline Storage - Underground Pond N8.b 777 sf min. area Include Perimeter Stone in Calculations Click Here for Metric 3 0.00 0.00 24.60 24.60 73.80 4905.45 2 0.00 0.00 24.60 24.60 49.20 4905.37 1 0.00 0.00 24.60 24.60 24.60 4905.28 StormTech SC-740 Cumulative Storage Volumes Timberline Storage - Underground Pond N8.a 406 sf min. area Include Perimeter Stone in Calculations Click Here for Metric Project Location : Design Point C = Design Storm Page 1 of 1 1269-001_Basin 8_DetentionVolume_FAAModified Method.xls Timberline Storage Project Number : Project Name : Underground Pond N2-4 Page 1 of 1 1269-001_Basin 2-4_DetentionVolume_FAAModified Method.xls Tc (min) 10-yr Tc (min) 100-yr Tc (min) n8 N8.a & N8.b No 0.94 0.94 1.00 377 0.75% 6.3 6.3 4.0 N/A N/A 0 N/A N/A N/A 6 6 5 COMBINED DEVELOPED TIME OF CONCENTRATION COMPUTATIONS B. Mathisen September 20, 2016 Design Point Basin IDs Overland Flow Gutter/Pipe Flow Swale Flow Time of Concentration (Equation RO-4) ( ) 3 1 1 . 87 1 . 1 * S C Cf L Ti = − Page 5 of 23 D:\Projects\1269-001\Drainage\Hydrology\1269-001_Rational-Calcs9.20.16.xlsx\Comb-Tc-10-yr_&_100-yr Slope, S (%) Velocity, V (ft/s) Tt (min) 2-yr Tc (min) 10-yr Tc (min) 100-yr Tc (min) n1 N1* No 0.72 0.72 0.88 N/A N/A N/A N/A N/A N/A N/A N/A 12 12 9 n2-4 N2-4 No 0.94 0.94 1.00 359 0.59% 6.7 6.7 4.2 N/A N/A N/A N/A N/A 7 7 5 n5 N5* No 0.79 0.79 1.00 25 3.00% 2.0 2.0 0.6 N/A N/A N/A N/A N/A 5 5 5 n8.a N8.a No 0.95 0.95 1.00 377 0.75% 6.0 6.0 4.0 N/A N/A N/A N/A N/A 6 6 5 n8.b N8.b No 0.94 0.94 1.00 386 1.50% 5.2 5.2 3.2 N/A N/A N/A N/A N/A 5 5 5 n9 N9* No 0.32 0.32 0.40 50 15.00% 4.2 4.2 3.8 N/A N/A N/A N/A N/A 5 5 5 n10 N10* No 0.80 0.80 1.00 N/A N/A N/A N/A N/A N/A N/A N/A 17 17 16 n13 N13* No 0.72 0.72 0.88 35 3.00% 2.9 2.9 1.7 N/A N/A N/A N/A N/A 5 5 5 DEVELOPED TIME OF CONCENTRATION COMPUTATIONS Gutter/Pipe Flow Swale Flow Design Point Basin Overland Flow B. Mathisen September 20, 2016 Time of Concentration (Equation RO-4) ( ) 3 1 1 . 87 1 . 1 * S C Cf L Ti = − Page 2 of 23 D:\Projects\1269-001\Drainage\Hydrology\1269-001_Rational-Calcs9.20.16.xlsx\Tc-10-yr_&_100-yr N9* 41992 0.964 0.093 0.000 0.000 0.000 0.000 0.87 0.32 0.32 0.40 69% N10* 109902 2.523 0.000 0.000 0.400 0.000 0.000 2.12 0.80 0.80 1.00 75% N13* 13615 0.313 0.014 0.001 0.046 0.000 0.000 0.25 0.72 0.72 0.88 66% TOTAL 307971 7.070 0.973 0.001 1.600 0.000 0.000 4.50 0.44 0.44 0.55 34% DEVELOPED COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS Runoff Coefficients are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3. % Impervious taken from UDFCD USDCM, Volume I. 10-year Cf = 1.00 September 20, 2016 **Soil Classification of site is Clay Loam** Page 1 of 23 D:\Projects\1269-001\Drainage\Hydrology\1269-001_Rational-Calcs9.20.16.xlsx\C-Values Total 3.633 ac. 3.374 ac. 93% 3.865 ac.