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HomeMy WebLinkAboutIMPALA REDEVELOPMENT - PDP220005 - SUBMITTAL DOCUMENTS - ROUND 5 - DRAINAGE REPORT PRELIMINARY DRAINAGE REPORT IMPALA REDEVELOPMENT FORT COLLINS, COLORADO OCTOBER 19, 2022 NORTHERNENGINEERING.COM 970.221.4158 FORT COLLINS GREELEY 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 necessary, we recommend double-sided printing. NORTHERNENGINEERING.COM | 970.221.4158 FORT COLLINS | GREELEY PRELIMINARY DRAINAGE REPORT: IMPALA REDEVELOPMENT COVER SHEET October 19, 2022 City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, CO 80521 RE: PRELIMINARY DRAINAGE REPORT FOR IMPALA REDEVELOPMENT Dear Staff, Northern Engineering is pleased to submit this Preliminary Drainage Report for your review. This report accompanies the Preliminary Development Plan submittal for the proposed Impala Redevelopment. This report has been prepared in accordance with the Fort Collins Stormwater Criteria Manual (FCSCM) and serves to document the stormwater impacts associated with the proposed Impala Redevelopment project. We understand that review by the City of Fort Collins is to assure general compliance with standardized criteria contained in the FCSCM. If you should have any questions as you review this report, please feel free to contact us. Sincerely, NORTHERN ENGINEERING SERVICES, INC. SHANE RITCHIE, PE DANNY WEBER, PE Project Engineer Project Manager Compliance Statement I hereby attest that this report for the Preliminary drainage design for Impala Redevelopment was prepared by me or under my direct supervision, in accordance with the provisions of the Fort Collins Stormwater Criteria Manual. I understand that the City of Fort Collins does not and will not assume liability for drainage facilities designed by others. NORTHERNENGINEERING.COM | 970.221.4158 FORT COLLINS | GREELEY PRELIMINARY DRAINAGE REPORT: IMPALA REDEVELOPMENT TABLE OF CONTENTS TABLE OF CONTENTS I. GENERAL LOCATION AND DESCRIPTION ....................................................................................... 4 II. DRAINAGE BASINS AND SUB-BASINS ............................................................................................ 6 III. DRAINAGE DESIGN CRITERIA ....................................................................................................... 6 IV. DRAINAGE FACILITY DESIGN ....................................................................................................... 8 V. CONCLUSIONS ........................................................................................................................ 10 VI. REFERENCES ........................................................................................................................... 11 TABLES AND FIGURES Figure 1 - Vicinity Map ................................................................................................................................ 4 Figure 2 - Aerial Photograph ..................................................................................................................... 5 Figure 3 - Existing Floodplains .................................................................................................................. 5 Table 1 - LID Summary ............................................................................................................................... 8 Table 2 - Detention Summary ................................................................................................................... 9 APPENDICES APPENDIX A – HYDROLOGIC COMPUTATIONS APPENDIX B – HYDRAULIC COMPUTATIONS APPENDIX C – LID & WATER QUALITY EXHIBITS APPENDIX D – USDA SOILS REPORT APPENDIX E – FEMA FIRMETTE MAP POCKET IMPV – IMPERVIOUS AREA EXHIBIT HILL CREST PUD POND SIZING EXHIBIT C 500 – HISTORIC DRAINAGE EXHIBIT C 501 – DRAIANGE EXHIBIT NORTHERNENGINEERING.COM | 970.221.4158 FORT COLLINS | GREELEY PRELIMINARY DRAINAGE REPORT: IMPALA REDEVELOPMENT | 11 I. GENERAL LOCATION AND DESCRIPTION A. LOCATION 1. Vicinity Map Figure 1 - Vicinity Map 2. The Impala Redevelopment project site is located in the northeast quarter of Section 9, Township 7 North, Range 69 West of the 6th Principal Meridian, City of Fort Collins, County of Larimer, State of Colorado. 3. The project site (refer to Figure 1) is bordered to the north and west by Poudre High School; to the east by single family homes; and to the south by W Mulberry Street and a future park tract. 4. There is existing storm drainage infrastructure that was constructed with Hill Crest PUD and Impala Subdivision. B. DESCRIPTION OF PROPERTY 1. The Impala Redevelopment is comprised of 7.20 acres. 2. The site is currently comprised of single-family and single-family attached housing, as well as associated parking, roadways, and open space. 3. The project site resides in the City of Fort Collins Canal Importation Master Drainage Basin. The detention requirements of the subject area were considered in the design of the detention ponds for Impala Redevelopment and have been factored into the LID requirements, which are described in further detail throughout this report. 4. The existing on-site runoff generally drains from the Northwest to the Southeast across flat grades (e.g., 0.50% - 2.00%) to West Mulberry Street. 5. According to the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Soil Survey website: (http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx), the site consists primarily of Altvan-Satanta loams (Hydrologic Soil Group B) and Nunn clay loam NORTHERNENGINEERING.COM | 970.221.4158 FORT COLLINS | GREELEY PRELIMINARY DRAINAGE REPORT: IMPALA REDEVELOPMENT | 11 (Hydrologic Soil Group C). Figure 2 - Aerial Photograph 6. The proposed development will consist of four (4) multi-family residential buildings containing 56 units with onsite and street parking, and a clubhouse. 7. The proposed land use is multi-family. This is a permitted use in the Low Density Mixed-Use Neighborhood District (LMN). C. FLOODPLAIN 1. No portions of the site are located in a FEMA regulatory floodplain. Figure 3 - Existing Floodplains NORTHERNENGINEERING.COM | 970.221.4158 FORT COLLINS | GREELEY PRELIMINARY DRAINAGE REPORT: IMPALA REDEVELOPMENT | 11 2. The City of Fort Collins High-Risk Canal Importation 100-year floodplain extends into the SE corner of the project site and the subject property will be required to comply with Chapter 10 of the City Municipal code and the development review floodplain checklist. 3. There are no special floodplain considerations required regarding finished floor elevations of building footprints. 4. A floodplain use permit will be required prior to construction for any work in the floodplain. II. DRAINAGE BASINS AND SUB-BASINS A. Major Basin Description The project area of the Impala Redevelopment is located within the City of Fort Collins Canal Importation Drainage Basin. Detention requirements for this basin are to detain the difference between the 100-yr developed inflow rate and the historic 2-year release rate. However, outflow from this property is limited by the previously established Hill Crest PUD using an orifice restricted total release rate of 5.8 cubic feet per second and existing storm infrastructure in W Mulberry Street. An excerpt from the Hill Crest PUD and Pond Sizing Exhibit have been provided in the Map Pocket for clarification. B. Sub-Basin Description 1. The outfall for the project site is at the south end of the project site to existing storm infrastructure in W Mulberry Street. 2. The existing subject site can be defined with 9 distinct drainage basins (see DR1 in the provided map pocket). 3. The existing site runoff generally drains from Northwest to Southeast towards W Mulberry Street. 4. The project area receives offsite runoff from the north. This was accounted for in the previous drainage report for the project and will continue to be accounted for with the proposed design. III. DRAINAGE DESIGN CRITERIA A. OPTIONAL PROVISIONS There are no optional provisions outside of the FCSCM proposed with Impala Redevelopment. B. STORMWATER MANAGEMENT STRATEGY The overall stormwater management strategy employed with Impala Redevelopment 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. The first consideration taken in trying to reduce the stormwater impacts of this development is the site selection itself. By choosing an already developed site with public storm sewer currently in place, the burden is significantly less than developing a vacant parcel absent of any infrastructure. Impala Redevelopment aims to reduce runoff peaks, volumes and pollutant loads from frequently occurring storm events (i.e., water quality (i.e., 80th percentile) and 2-year storm events) by implementing Low Impact Development (LID) strategies. Wherever practical, runoff will be routed across landscaped areas or through a rain garden or water quality pond. These LID practices reduce the overall amount of impervious area, while at the same time Minimizing Directly Connected Impervious Areas (MDCIA). The combined LID/MDCIA techniques will be implemented, where practical, throughout the development, thereby slowing runoff and increasing opportunities for infiltration. Step 2 – Implement BMPs that Provide a Water Quality Capture Volume (WQCV) with Slow Release. The efforts taken in Step 1 will help to minimize excess runoff from frequently occurring NORTHERNENGINEERING.COM | 970.221.4158 FORT COLLINS | GREELEY PRELIMINARY DRAINAGE REPORT: IMPALA REDEVELOPMENT | 11 storm events; however, urban development of this intensity will still have stormwater runoff leaving the site. The primary water quality treatment will occur between several rain gardens between major parking areas of the property and the existing detention ponds installed for Impala Redevelopment. Step 3 – Stabilize Drainageways. While not directly applicable to this site, the project will pay one- time stormwater development fees as well as ongoing monthly stormwater utility fees, both of which help achieve citywide drainageway stability. Step 4 – Implement Site Specific and Other Source Control BMPs. This step typically applies to industrial and commercial developments. C. DEVELOPMENT CRITERIA REFERENCE AND CONSTRAINTS 1. The subject property is not part of an overall development plan. 2. The project area is constrained to the north and west by Poudre High School; to the east by single family homes; and to the south by W Mulberry Street and a future park tract. D. HYDROLOGICAL CRITERIA 1. The City of Fort Collins Rainfall Intensity-Duration-Frequency Curves, as depicted in Figure 3.4-1 of the FCSCM, serve as the source for all hydrologic computations associated with the Impala Redevelopment project. Tabulated data contained in Table 3.4-1 has been utilized for Rational Method runoff calculations. 2. The Rational Method has been used to estimate peak developed stormwater runoff from drainage basins within the developed site for the 2-year, 10-year, and 100-year design storms. Peak runoff discharges determined using this methodology have been used to check the street capacities, inlets, swales, and storm drain lines. 3. 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. E. HYDRAULIC CRITERIA 1. The drainage facilities proposed with the Impala Redevelopment project are designed in accordance with criteria outlined in the FCSCM. 2. As stated in Section I.C.1, above, the subject property is not located next to a FEMA designated floodplain, however, it is located within the Canal Importation High-Risk City Floodplain. F. FLOODPLAIN REGULATIONS COMPLIANCE As previously mentioned, this project is not adjacent to a FEMA regulated floodplain, but a portion of the project falls within a City 100-yr Floodplain and will be subject to these regulations. G. MODIFICATIONS OF CRITERIA There are no formal modifications outside of the FCSCM proposed with Impala Redevelopment. H. CONFORMANCE WITH WATER QUALITY TREATMENT CRITERIA City Code requires that 100% of runoff from new or modified areas in a project site shall receive some sort of water quality treatment, of which a majority of the site is receiving. There are several small areas that flow directly offsite, without treatment. While these small areas will not receive formal water quality treatment, most areas will still see some treatment as runoff is directed through the landscaped areas or through extended detention basins before leaving the site. I. CONFORMANCE WITH LOW IMPACT DEVELOPMENT (LID) The project site will conform with the requirement to treat a minimum of 75% of new or modified impervious area using a LID technique. The proposed project site will treat 95% of modified area NORTHERNENGINEERING.COM | 970.221.4158 FORT COLLINS | GREELEY PRELIMINARY DRAINAGE REPORT: IMPALA REDEVELOPMENT | 11 with LID, with small portions of the site flowing directly offsite. One rain garden will be used to capture and treat most of the impervious area on the project site. J. SIZING OF LID & WQ FACILITIES Rain Gardens/Underground Chambers 1. The rain gardens were sized by first determining the required water quality capture volume (WQCV) for Sub-basin 100. 2. Once the WQCV was identified, the rain garden area was sized for its respective WQCV. The rain garden will be constructed with a biomedia filter and underdrain. An overflow drain will be provided in each rain garden to pass storms greater than the WQCV. Table 1 - LID Summary LID ID Area (ft2) Weighted % Impervious Volume per UD-BMP (ft3) Vol. w/ 20% increase per FC Manual (ft3) Impervious area (ft2) Rain Garden 1 111,7088 61% 1,780 2,136 68,113 Water Quality 3. The existing Pond 2 does not have a water quality plate and is only constrained by an orifice plate. 4. A proposed Water Quality Weir is being proposed upstream of the existing headwall as a retrofit to provide water quality for the existing pond. IV. DRAINAGE FACILITY DESIGN A. GENERAL CONCEPT 1. The main objective of the Impala Redevelopment drainage design is to maintain existing drainage patterns, while not adversely impacting adjacent properties. 2. All storm drains on the site have been designed to convey 100-yr flows. 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. Drainage for the project site has been analyzed using 9 drainage sub-basins, designated as sub- basins 100-102, 200, ad OS1-OS5. All sub-basins aside from OS2 are om-site basins. OS2 is an off- site basin whose flow are collected in Detention Pond 1. Sub-basins OS1, OS3, OS4, and OS5 flow off-site and are not treated with any form of water quality. Sub-Basin 100 Sub-basin 100 is comprised of multi-family residential, asphalt drives and parking, and landscaped areas. The flows from this basin travel via overland flow, curb and gutter, and storm pipe to Rain Garden 1. From Rain Garden 1, flows are discharged via an underdrain and overflow weir into Detention Pond 1, which was modified to accommodate the needs of the modified site area. Sub-Basin 101 Sub-Basin 101 is composed of existing duplexes, landscaped area, Rain Garden 1, and modified Detention Pond 1. Flows travel via overland flow to Detention Pond 1. NORTHERNENGINEERING.COM | 970.221.4158 FORT COLLINS | GREELEY PRELIMINARY DRAINAGE REPORT: IMPALA REDEVELOPMENT | 11 Sub-Basin 102 Sub-Basin 102 is comprised of existing duplexes, paved drives and parking, and landscaped area. The flows from this basin are conveyed via overland flow, curb and gutter flow, and concrete pan to Detention Pond 1. Sub-Basin 200 Sub-Basin 200 is comprised of existing duplexes, asphalt drives and parking, landscaped areas, and proposed multi-family. Sub-Basin 200 contains Detention Pond 2. Detention Pond 2 was previously proposed with Hill Crest P.U.D but is being modified to better suit the needs of the proposed site including adding a water quality headwall with a proposed water quality plate. Sub-Basin OS1 Sub-Basin OS1 is composed of multi-family buildings, concrete walks, and landscaped areas. The flows from this basin travel via overland flow directly offsite and are not treated for water quality or captured. This follows historic patterns and will still allow for 75% of the modified site area to be treated with LID. Sub-Basin OS2 Sub-Basin OS2 Is comprised of existing off-site soccer and baseball fields whose flow is accounted for in Detention Pond 1’s sizing. Overland flow is the primary method in which these flows travel to Detention Pond 1. These flows are not treated by LID. Sub-Basins OS3 and OS4 Sub-Basins OS3 and OS4 are composed of existing and proposed buildings, landscaped area, and paved roadways. Flows from these basins travel via overland flow and curb and gutter flow to W Mulberry Street. These flows are not captured nor were they planned to be captured with Hill Crest P.U.D. Sub-Basins OS5 Sub-Basin OS5 is composed of a small portion of proposed roadway and sidewalk. These flows travel directly offsite and are not captured or treated. A full-size copy of the Drainage Exhibit can be found in the Map Pocket at the end of this report. B. SPECIFIC DETAILS 1. There are 2 existing detention ponds on the project site, both of which are being modified to accommodate the additional impervious area being added to the existing site. These ponds will detain up to the 100-yr storm event and release at or below the previously calculated release rates. See Table 2 for detention summary. Table 2 - Detention Summary 2. LID treatment is being provided within Rain Garden 1. These treat approximately 77% of the modified site impervious runoff, which is more than the required 75% LID treatment. Please see the LID exhibit and calculations in Appendix C. Pond ID Tributary Area (Ac) Ave Percent Imperviousness (%) Extended Detention WQCV (Ac-Ft) 100-Yr. Detention Vol. (Ac-Ft) 100-Yr. Detention WSEL(Ft) Peak Release (cfs) Pond 1 2.51 64 N/A 0.73 5086.26 4.50 Pond 2 6.64 24 0.022 0.32 5082.46 5.79 POND SUMMARY TABLE NORTHERNENGINEERING.COM | 970.221.4158 FORT COLLINS | GREELEY PRELIMINARY DRAINAGE REPORT: IMPALA REDEVELOPMENT | 11 3. Detention allowable release rate is based on computed 2-year historic flow for the overall property as proposed with Hill Crest P.U.D. 4. Stormwater facility Standard Operations Procedures (SOP) will be provided by the City of Fort Collins in the Development Agreement. 5. Preliminary Design details, and construction documentation shall be provided to the City of Fort Collins for review prior to Final Development Plan approval. V. CONCLUSIONS A. COMPLIANCE WITH STANDARDS 1. The drainage design proposed with Impala Redevelopment complies with the City of Fort Collins Master Drainage Plan for the Canal Importation Basin. 2. The drainage plan and stormwater management measures proposed with the Impala Redevelopment project are compliant with all applicable State and Federal regulations governing stormwater discharge. B. DRAINAGE CONCEPT 1. The drainage plan and stormwater management measures proposed with the Impala Redevelopment project are compliant with all applicable State and Federal regulations governing stormwater discharge. 2. Impala Redevelopment will not impact the Master Drainage Plan recommendations for the City of Fort Collins Canal Importation Major Drainage Basin. 3. The proposed drainage plan for the Impala Redevelopment complies with the previously proposed impervious values for the site from the Hill Crest P.U.D plan dated February 1995. The proposed project will also release at the same rates proposed with Hill Crest P.U.D. For this reason, it is believed the downstream infrastructure will continue to be sufficient as this portion of the site is developed. NORTHERNENGINEERING.COM | 970.221.4158 FORT COLLINS | GREELEY PRELIMINARY DRAINAGE REPORT: IMPALA REDEVELOPMENT | 11 VI. REFERENCES 1. Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, as adopted by Ordinance No. 159, 2018, and referenced in Section 26-500 of the City of Fort Collins Municipal Code. 2. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation Service, United States Department of Agriculture. 3. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control District, Wright- McLaughlin Engineers, Denver, Colorado, Revised April 2008. 4. Final Storm Drainage Report for Hill Crest P.U.D, Stewart & Associates, Fort Collins, Colorado, dated February 1995. NORTHERNENGINEERING.COM | 970.221.4158 FORT COLLINS | GREELEY PRELIMINARY DRAINAGE REPORT: IMPALA REDEVELOPMENT APPENDIX APPENDIX A HYDROLOGIC COMPUTATIONS CHARACTER OF SURFACE1: Percentage Impervious 2-yr Runoff Coefficient 10-yr Runoff Coefficient 100-yr Runoff Coefficient Developed Asphalt .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………100%0.95 0.95 1.00 Concrete .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………100%0.95 0.95 1.00 Rooftop .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………90%0.95 0.95 1.00 Gravel .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………50%0.50 0.50 0.63 Pavers .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………40%0.50 0.50 0.63 Residential (Low Density).…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………50%0.55 0.55 0.69 Landscape or Pervious Surface Playgrounds .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………25%0.35 0.35 0.44 Lawns Clayey Soil .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………2%0.25 0.25 0.31 Lawns Sandy Soil .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………2%0.15 0.15 0.19 Notes: Basin ID Basin Area (ac) Area of Asphalt/Co ncrete (ac) Area of Concrete (ac) Area of Rooftop (ac) Area of Single Family (ac) Area of Gravel (ac) Area of Pavers (ac) Area of Playgrounds (ac) Area of Lawns (ac) Composite % Imperv. 2-year Composite Runoff Coefficient 10-year Composite Runoff Coefficient 100-year Composite Runoff Coefficient 100 2.420 0.54 0.41 0.28 0.00 0.00 0.00 0.00 1.60 51% 0.65 0.65 0.71 101 0.838 0.00 0.00 0.07 0.00 0.00 0.00 0.00 0.77 9% 0.31 0.31 0.37 102 1.948 0.49 0.31 0.27 0.00 0.00 0.00 0.00 0.88 54% 0.63 0.63 0.69 200 1.992 0.13 0.07 0.18 0.00 0.00 0.00 0.00 1.68 20% 0.39 0.39 0.45 Offsite Basins OS1 0.359 0.00 0.06 0.05 0.00 0.00 0.00 0.00 0.30 30% 0.49 0.49 0.55 OS2 4.929 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4.93 2% 0.25 0.25 0.31 OS3 0.343 0.11 0.00 0.00 0.00 0.00 0.00 0.00 0.24 32% 0.47 0.47 0.53 OS4 0.287 0.14 0.02 0.00 0.00 0.00 0.00 0.00 0.12 58% 0.65 0.65 0.70 Total On-Site 7.20 1.16 0.79 0.79 0.00 0.00 0.00 0.00 4.46 38% 0.52 0.52 0.57 HISTORIC BASIN % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS 2) Runoff Coefficients are taken from the Fort Collins Stormwater Criteria Manual, Chapter 3. Table 3.2-1 and 3.2-2 1) Percentage impervious taken from the Fort Collins Stormwater Criteria Manual, Chapter 5, Table 4.1-2 and Table 4.1-3 Overland Flow, Time of Concentration: Channelized Flow, Time of Concentration: Total Time of Concentration : T c is the lesser of the values of Tc calculated using T c = T i + T t C2 C100 Length, L (ft) Slope, S (%) Ti2 Ti100 Length, L (ft) Slope, S (%) Roughness Coefficient Assumed Hydraulic Radius Velocity, V (ft/s) Tt (min)Tc (Eq. 3.3-5) Tc2 = Ti +Tt Tc100 = Ti +Tt Tc2 Tc100 100 100 0.65 0.71 0 N/A N/A N/A 739 1.24% 0.015 0.59 7.80 1.6 N/A 1.6 1.6 5.0 5.0 101 102 0.63 0.69 52 3.85% 4.0 N/A 404 0.45% 0.015 0.59 4.69 1.4 12.5 5.5 1.4 5.5 5.0 102 200 0.39 0.45 0 N/A N/A N/A 362 0.54% 0.015 0.59 5.13 1.2 N/A 1.2 1.2 5.0 5.0 200 200 0.39 0.45 0 N/A N/A N/A 521 1.23% 0.015 0.59 7.74 1.1 N/A 1.1 1.1 5.0 5.0 os1 OS1 0.49 0.55 71 0.24% 15.5 14.0 0 N/A 0.015 0.59 N/A N/A 10.4 15.5 14.0 10.4 10.4 os2 OS2 0.25 0.31 300 2.06% 21.6 20.1 410 0.91% 0.015 0.59 6.66 1.0 13.9 22.7 21.1 13.9 13.9 os3 OS3 0.47 0.53 92 3.26% 7.6 6.9 102 0.13% 0.015 0.59 2.49 0.7 11.1 8.3 7.6 8.3 7.6 os4 OS4 0.65 0.70 58 2.55% 4.7 4.2 136 1.54% 0.038 0.50 3.06 0.7 11.1 5.4 4.9 5.4 5.0 HISTORIC DIRECT TIME OF CONCENTRATION Channelized Flow Design Point Basin Overland Flow Time of Concentration Frequency Adjustment Factor: Offsite Basins (Equation 3.3-2 FCSCM) (Equation 5-5 FCSCM) (Equation 5-4 FCSCM) (Equation 3.3-5 FCSCM) Table 3.2-3 FCSCM Therefore Tc2=Tc10 Notes: 1) Add 5000 to all elevations. 2) Per Fort Collins Stormwater Manual, minimum Tc = 5 min. 3) Assume a water depth of 6" and a typical curb and gutter per Larimer County Urban Street Standard Detail 701 for curb and gutter channelized flow. Assume a water depth of 1', fixed side slopes, and a triangular swale section for grass channelized flow. Assume a water depth of 1', 4:1 side slopes, and a 2' wide valley pan for channelized flow in a valley pan. Rational Method Equation: Rainfall Intensity: 100 100 2.42 5.0 5.0 0.65 0.71 2.85 4.87 7.00 4.48 7.66 12.03 101 102 0.84 5.0 5.0 0.31 0.37 2.85 4.87 7.00 0.74 1.27 2.17 102 200 1.95 5.0 5.0 0.63 0.69 2.85 4.87 7.00 3.50 5.98 9.41 200 200 1.99 5.0 5.0 0.39 0.45 2.85 2.85 7.00 2.21 2.21 6.27 os1 OS1 0.36 10.4 10.4 0.49 0.55 2.21 2.21 6.80 0.39 0.39 1.34 os2 OS2 4.93 13.9 13.9 0.25 0.31 1.95 1.95 6.24 2.40 2.40 9.54 os3 OS3 0.34 7.6 7.6 0.47 0.53 2.46 2.46 6.94 0.40 0.40 1.26 os4 OS4 0.29 5.0 5.0 0.65 0.70 2.85 2.85 7.00 0.53 0.53 1.41 Tc100 (min) Intensity, i2 (in/hr) Intensity, i100 (in/hr) Offsite Basins HISTORIC RUNOFF COMPUTATIONS Design Point Basin(s)Area, A (acres) Tc2 (min) Flow, Q2 (cfs) Flow, Q100 (cfs) C2 C100 IDF Table for Rational Method - Table 3.4-1 FCSCM Intensity, i10 (in/hr) Flow, Q10 (cfs) ()()()AiCCQf= CHARACTER OF SURFACE1: Percentage Impervious 2-yr Runoff Coefficient 10-yr Runoff Coefficient 100-yr Runoff Coefficient Developed Asphalt .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………100%0.95 0.95 1.00 Concrete .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………100%0.95 0.95 1.00 Rooftop .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………90%0.95 0.95 1.00 Gravel .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………40%0.50 0.50 0.63 Pavers .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………40%0.50 0.50 0.63 Residential (Low Density).…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………50%0.55 0.55 0.69 Landscape or Pervious Surface Playgrounds .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………25%0.35 0.35 0.44 Lawns Clayey Soil .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………2%0.25 0.25 0.31 Lawns Sandy Soil .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………2%0.15 0.15 0.19 Notes: Basin ID Basin Area (ac) Area of Asphalt/Co ncrete (ac) Area of Concrete (ac) Area of Rooftop (ac) Area of Single Family (ac) Area of Gravel (ac) Area of Pavers (ac) Area of Playgrounds (ac) Area of Lawns (ac) Composite % Imperv. 2-year Composite Runoff Coefficient 10-year Composite Runoff Coefficient 100-year Composite Runoff Coefficient 100 2.56 0.93 0.31 0.56 0.00 0.00 0.00 0.00 1.07 69% 0.77 0.77 0.83 101 0.84 0.00 0.00 0.07 0.00 0.00 0.00 0.00 0.77 9% 0.31 0.31 0.39 102 1.95 0.49 0.31 0.27 0.00 0.00 0.00 0.00 0.88 54% 0.63 0.63 0.79 200 1.99 0.14 0.13 0.20 0.00 0.00 0.00 0.00 1.65 24% 0.43 0.43 0.54 Offsite Basins 0.00 OS1 0.20 0.00 0.04 0.11 0.00 0.00 0.00 0.00 0.05 72% 0.79 0.79 0.99 OS2 4.93 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4.93 2% 0.25 0.25 0.31 OS3 0.04 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.04 2% 0.25 0.25 0.31 OS4 0.29 0.14 0.02 0.00 0.00 0.00 0.00 0.00 0.12 58% 0.65 0.65 0.81 OS5 0.01 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100% 0.95 0.95 1.00 Pond 1 10.28 1.42 0.62 0.89 0.00 0.00 0.00 0.00 7.34 29% 0.45 0.45 0.56 Total On-Site 7.34 1.56 0.75 1.09 0.00 0.00 0.00 0.00 3.94 46% 0.57 0.57 0.63 DEVELOPED BASIN % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS 2) Runoff Coefficients are taken from the Fort Collins Stormwater Criteria Manual, Chapter 3. Table 3.2-1 and 3.2-2 1) Percentage impervious taken from the Fort Collins Stormwater Criteria Manual, Chapter 5, Table 4.1-2 and Table 4.1-3 Overland Flow, Time of Concentration: Channelized Flow, Time of Concentration: Total Time of Concentration : T c is the lesser of the values of Tc calculated using T c = T i + T t C2 C100 Length, L (ft) Slope, S (%) Ti2 Ti100 Length, L (ft) Slope, S (%) Roughness Coefficient Assumed Hydraulic Radius Velocity, V (ft/s) Tt (min)Tc (Eq. 3.3-5) Tc2 = Ti +Tt Tc100 = Ti +Tt Tc2 Tc100 100 100 0.77 0.83 0 N/A N/A N/A 515 1.34% 0.015 0.59 8.09 1.1 N/A 1.1 1.1 5.0 5.0 101 101 0.31 0.39 82 2.38% 10.0 N/A 323 0.52% 0.015 0.59 5.02 1.1 12.3 11.1 1.1 11.1 5.0 102 102 0.63 0.79 0 N/A N/A N/A 362 0.54% 0.015 0.59 5.13 1.2 N/A 1.2 1.2 5.0 5.0 200 200 0.43 0.54 0 N/A N/A N/A 521 1.23% 0.015 0.59 7.74 1.1 N/A 1.1 1.1 5.0 5.0 os1 OS1 0.79 0.99 55 2.47% 3.2 1.2 0 N/A 0.015 0.59 N/A N/A 10.3 3.2 1.2 5.0 5.0 os2 OS2 0.25 0.31 300 2.06% 21.6 20.1 410 0.91% 0.015 0.59 6.66 1.0 13.9 22.7 21.1 13.9 13.9 os3 OS3 0.25 0.31 92 3.26% 10.3 9.5 102 0.13% 0.015 0.59 2.49 0.7 11.1 11.0 10.2 11.0 10.2 os4 OS4 0.65 0.81 58 1.79% 5.3 3.4 136 1.54% 0.038 0.50 3.06 0.7 11.1 6.0 4.1 6.0 5.0 os5 OS5 0.95 1.00 58 1.79% 1.8 1.2 136 1.54% 0.038 0.50 3.06 0.7 11.1 2.5 1.9 5.0 5.0 Offsite Basins DEVELOPED DIRECT TIME OF CONCENTRATION Channelized Flow Design Point Basin Overland Flow Time of Concentration Frequency Adjustment Factor: (Equation 3.3-2 FCSCM) (Equation 5-5 FCSCM) (Equation 5-4 FCSCM) (Equation 3.3-5 FCSCM) Table 3.2-3 FCSCM Therefore Tc2=Tc10 Notes: 1) Add 5000 to all elevations. 2) Per Fort Collins Stormwater Manual, minimum Tc = 5 min. 3) Assume a water depth of 6" and a typical curb and gutter per Larimer County Urban Street Standard Detail 701 for curb and gutter channelized flow. Assume a water depth of 1', fixed side slopes, and a triangular swale section for grass channelized flow. Assume a water depth of 1', 4:1 side slopes, and a 2' wide valley pan for channelized flow in a valley pan. Rational Method Equation: Rainfall Intensity: 100 100 2.56 5.0 5.0 0.77 0.83 2.85 4.87 9.95 5.63 9.62 21.18 101 101 0.84 5.0 5.0 0.31 0.39 2.85 4.87 9.95 0.74 1.27 3.23 102 102 1.95 5.0 5.0 0.63 0.79 2.85 4.87 9.95 3.50 5.98 15.26 200 200 1.99 5.0 5.0 0.43 0.54 2.85 2.85 9.95 2.44 2.44 10.65 os1 OS1 0.20 5.0 5.0 0.79 0.99 2.85 2.85 9.95 0.46 0.46 1.99 os2 OS2 4.93 13.9 13.9 0.25 0.31 1.95 1.95 6.82 2.40 2.40 10.50 os3 OS3 0.04 10.2 10.2 0.25 0.31 2.21 2.21 7.72 0.02 0.02 0.09 os4 OS4 0.29 5.0 5.0 0.65 0.81 2.85 2.85 9.95 0.53 0.53 2.32 os5 OS5 0.01 5.0 5.0 0.95 1.00 2.85 2.85 9.95 0.04 0.04 0.13 Tc100 (min) Intensity, i2 (in/hr) Intensity, i100 (in/hr) Offsite Basins DEVELOPED RUNOFF COMPUTATIONS Design Point Basin(s)Area, A (acres) Tc2 (min) Flow, Q2 (cfs) Flow, Q100 (cfs) C2 C100 IDF Table for Rational Method - Table 3.4-1 FCSCM Intensity, i10 (in/hr) Flow, Q10 (cfs) ()()()AiCCQf= Pond No :1 1 100-yr 0.91 5.00 min 14203 ft3 2.56 acres 0.33 ac-ft Max Release Rate =2.80 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 6954 1.00 2.80 840 6114 10 7.720 10791 1.00 2.80 1680 9111 15 6.520 13670 1.00 2.80 2520 11150 20 5.600 15655 1.00 2.80 3360 12295 25 4.980 17402 1.00 2.80 4200 13202 30 4.520 18954 1.00 2.80 5040 13914 35 4.080 19960 1.00 2.80 5880 14080 40 3.740 20910 1.00 2.80 6720 14190 45 3.460 21763 1.00 2.80 7560 14203 50 3.230 22574 1.00 2.80 8400 14174 55 3.030 23294 1.00 2.80 9240 14054 60 2.860 23986 1.00 2.80 10080 13906 65 2.720 24712 1.00 2.80 10920 13792 70 2.590 25341 1.00 2.80 11760 13581 75 2.480 25998 1.00 2.80 12600 13398 80 2.380 26613 1.00 2.80 13440 13173 85 2.290 27207 1.00 2.80 14280 12927 90 2.210 27801 1.00 2.80 15120 12681 95 2.130 28284 1.00 2.80 15960 12324 100 2.060 28794 1.00 2.80 16800 11994 105 2.000 29353 1.00 2.80 17640 11713 110 1.940 29828 1.00 2.80 18480 11348 115 1.890 30380 1.00 2.80 19320 11060 120 1.840 30863 1.00 2.80 20160 10703 *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 Increase Fort Collins, CO 1914-001 Impala Redevelopment Project Number : Project Name : A = Tc = Project Location : Design Point C = Design Storm 7/27/2022 10:20 AM 1914-001_FAA_Pond 1 (north) FAA Northern Engineering Services Pond No :2 1 100-yr 1.00 5.00 min 1338 ft3 0.12 acres 0.03 ac-ft Max Release Rate =0.04 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 9.950 358 1.00 0.04 11 348 10 7.720 556 1.00 0.04 21 535 15 6.520 704 1.00 0.04 32 673 20 5.600 806 1.00 0.04 42 764 25 4.980 896 1.00 0.04 53 844 30 4.520 976 1.00 0.04 63 913 35 4.080 1028 1.00 0.04 74 955 40 3.740 1077 1.00 0.04 84 993 45 3.460 1121 1.00 0.04 95 1026 50 3.230 1163 1.00 0.04 105 1058 55 3.030 1200 1.00 0.04 116 1084 60 2.860 1236 1.00 0.04 126 1109 65 2.720 1273 1.00 0.04 137 1136 70 2.590 1305 1.00 0.04 147 1158 75 2.480 1339 1.00 0.04 158 1182 80 2.380 1371 1.00 0.04 168 1203 85 2.290 1401 1.00 0.04 179 1223 90 2.210 1432 1.00 0.04 189 1243 95 2.130 1457 1.00 0.04 200 1257 100 2.060 1483 1.00 0.04 210 1273 105 2.000 1512 1.00 0.04 221 1291 110 1.940 1536 1.00 0.04 231 1305 115 1.890 1565 1.00 0.04 242 1323 120 1.840 1590 1.00 0.04 252 1338 *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 Increase Fort Collins, CO 1914-001 Impala Housing Catalyst Project Number : Project Name : A = Tc = Project Location : Design Point C = Design Storm 7/27/2022 10:22 AM 1914-001_FAA_Pond 2 (south) FAA Northern Engineering Services NORTHERNENGINEERING.COM | 970.221.4158 FORT COLLINS | GREELEY PRELIMINARY DRAINAGE REPORT: IMPALA REDEVELOPMENT APPENDIX APPENDIX B HYDRAULIC COMPUTATIONS Preliminary Drainage Report November 10, 2020 Watermark Residential This section intentionally left blank. Hydraulic calculations will be completed during final design. NORTHERNENGINEERING.COM | 970.221.4158 FORT COLLINS | GREELEY PRELIMINARY DRAINAGE REPORT: IMPALA REDEVELOPMENT APPENDIX APPENDIX C LID & WATER QUALITY EXHIBITS Project Number:Project: Project Location: Calculations By:Date: Sq. Ft. Acres 100 109,270 2.51 64%Rain Garden 1 Rain Garden 2,158 69,933 101 36,520 0.84 9%n/a n/a 0 3,287 200 (NEW or Modified)11,638 0.27 100%n/a n/a 877 11,638 OS1 10,135 0.20 72% n/a n/a 0 7,297 OS5 590 0.01 100% n/a n/a 0 590 Total 168,153 1.31 92,745 LID Summary Project Number:Project: Project Location: Calculations By:Date: LID Summary per LID Structure Sq. Ft. Acres Rain Garden 1 111,708 2.56 64%101 Rain Garden 1,798 2,158 71,493 Total 111,708 2.56 2,158 71,493 168,153 ft2 92,745 ft2 10,584 ft2 69,559 ft2 71,493 ft2 77.09% LID ID Volume per UD-BMP (ft3) Total Treated Area Percent Impervious Treated by LID O1-O7 75% Requried Minimum Area to be Treated LID Site Summary - New Impervious Area Total Area of Current Development Total Impervious Area Total Impervious Area without LID Treatment Impervious Area (ft2) Vol. w/20% Increase per Fort Collins Manual (ft3) Impala Redevelopment 7/27/2022 Subbasin ID Treatment Type Area Weighted % Impervious 1914-001 Fort Collins, Colorado C. Ungerman LID Summary AreaBasin ID Treatment TypePercent Impervious LID ID Impala Redevelopment 7/27/2022 1914-001 Fort Collins, Colorado S. Ritchie Total Impervious Area (ft2) Required Volume (ft3) LID Summary per Basin XSTTTTVAULTF.O.XXXXXXXXXSX SIRR IRRSSSFODSSDSTSTSTSTXXXX T T POND 1WHWHWHWHUPB B B B BB B BB BBBBBBB B B B B B B B BBBBBBB BBB BB B B B B B B B B B B BBB B BBBB B B BB B B B B B B B B B B B BBB BBBB BB BB B B B B B B XXOS1102OS2101OS3OS4101OS1102OS3OS4OS2200200DETENTIONPOND 2100100RAIN GARDEN 1RAIN GARDEN 2OS5OS5DRAWN BY:SCALE:ISSUED:IMPALAREDEVELOPMENTSHEET NO:LID EXHIBITC. Ungerman1in=120ft4/13/22PROPOSED STORM SEWERPROPOSED CURB & GUTTERPROPERTY BOUNDARYPROPOSED INLETADESIGN POINTDRAINAGE BASIN LABELDRAINAGE BASIN BOUNDARYALEGEND:( IN FEET )1 inch = ft.Feet0120120120RAIN GARDEN LIMITSSTORMTECH CHAMBERSFOR DRAINAGE REVIEW ONLYNOT FOR CONSTRUCTION Sheet 1 of 2 Designer: Company: Date: Project: Location: 1. Basin Storage Volume A) Effective Imperviousness of Tributary Area, Ia Ia =62.0 % (100% if all paved and roofed areas upstream of rain garden) B) Tributary Area's Imperviousness Ratio (i = Ia/100)i = 0.620 C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.19 watershed inches (WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i) D) Contributing Watershed Area (including rain garden area) Area = 111,708 sq ft E) Water Quality Capture Volume (WQCV) Design Volume VWQCV =cu ft Vol = (WQCV / 12) * Area F) For Watersheds Outside of the Denver Region, Depth of d6 = in Average Runoff Producing Storm G) For Watersheds Outside of the Denver Region, VWQCV OTHER =cu ft Water Quality Capture Volume (WQCV) Design Volume H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER =2,172 cu ft (Only if a different WQCV Design Volume is desired) 2. Basin Geometry A) WQCV Depth (12-inch maximum)DWQCV =12 in B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 5.00 ft / ft (Use "0" if rain garden has vertical walls) C) Mimimum Flat Surface Area AMin =1385 sq ft D) Actual Flat Surface Area AActual =1668 sq ft E) Area at Design Depth (Top Surface Area)ATop =2693 sq ft F) Rain Garden Total Volume VT=2,181 cu ft (VT= ((ATop + AActual) / 2) * Depth) 3. Growing Media 4. Underdrain System A) Are underdrains provided? B) Underdrain system orifice diameter for 12 hour drain time i) Distance From Lowest Elevation of the Storage y =ft Volume to the Center of the Orifice ii) Volume to Drain in 12 Hours Vol12 =cu ft iii) Orifice Diameter, 3/8" Minimum DO = in Design Procedure Form: Rain Garden (RG) C. Ungerman Northern Engineering July 27, 2022 Impala Redevelopment Rain garden 1 UD-BMP (Version 3.07, March 2018) Choose One Choose One 18" Rain Garden Growing Media Other (Explain): YES NO UD-BMP_v3.07_Rain Garden 1, RG 7/27/2022, 10:16 AM Sheet 2 of 2 Designer: Company: Date: Project: Location: 5. Impermeable Geomembrane Liner and Geotextile Separator Fabric A) Is an impermeable liner provided due to proximity of structures or groundwater contamination? 6. Inlet / Outlet Control A) Inlet Control 7. Vegetation 8. Irrigation A) Will the rain garden be irrigated? Notes: Design Procedure Form: Rain Garden (RG) C. Ungerman Northern Engineering July 27, 2022 Impala Redevelopment Rain garden 1 Choose One Choose One Choose One Sheet Flow- No Energy Dissipation Required Concentrated Flow- Energy Dissipation Provided Plantings Seed (Plan for frequent weed control) Sand Grown or Other High Infiltration Sod Choose One YES NO YES NO UD-BMP_v3.07_Rain Garden 1, RG 7/27/2022, 10:16 AM Project Number:1914-001 Project:Impala Redevelopment Date:7/27/2022 Prepared By:S. Ritchie 1.990 <-- INPUT from impervious calcs 24.00 <-- INPUT from impervious calcs 0.2400 <-- CALCULATED 0.131 <-- CALCULATED from UDFCD Figure 3-2 WQCV (ac-ft) =0.022 <-- CALCULATED from UDFCD DCM V.3 Section 3.0 WQ Depth (ft) =0.750 <-- INPUT from stage-storage table 0.099 <-- CALCULATED from Figure EDB-3 dia (in) =1/4 <-- INPUT from Figure 5 number of holes =2 <-- INPUT from Figure 5 t (in) =0.500 <-- INPUT from Figure 5 number of rows =1.000 <-- CALCULATED from WQ Depth and row spacing WQCV (watershed inches) = AREA REQUIRED PER ROW, a (in2) = CIRCULAR PERFORATION SIZING: WATER QUALITY POND DESIGN CALCULATIONS Pond 2 REQUIRED STORAGE & OUTLET WORKS: BASIN AREA = BASIN IMPERVIOUSNESS PERCENT = BASIN IMPERVIOUSNESS RATIO = NORTHERNENGINEERING.COM | 970.221.4158 FORT COLLINS | GREELEY PRELIMINARY DRAINAGE REPORT: IMPALA REDEVELOPMENT APPENDIX APPENDIX D USDA SOILS 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 Area, ColoradoNatural Resources Conservation Service March 29, 2022 Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/ portal/nrcs/main/soils/health/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/? cid=nrcs142p2_053951). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey information. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require 2 alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. 3 Contents Preface....................................................................................................................2 How Soil Surveys Are Made..................................................................................5 Soil Map..................................................................................................................8 Soil Map................................................................................................................9 Legend................................................................................................................10 Map Unit Legend................................................................................................11 Map Unit Descriptions.........................................................................................11 Larimer County Area, Colorado......................................................................13 3—Altvan-Satanta loams, 0 to 3 percent slopes.........................................13 35—Fort Collins loam, 0 to 3 percent slopes..............................................15 74—Nunn clay loam, 1 to 3 percent slopes.................................................16 76—Nunn clay loam, wet, 1 to 3 percent slopes.........................................17 Soil Information for All Uses...............................................................................20 Soil Properties and Qualities..............................................................................20 Soil Erosion Factors........................................................................................20 K Factor, Whole Soil....................................................................................20 Soil Qualities and Features.............................................................................23 Hydrologic Soil Group.................................................................................23 References............................................................................................................28 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 5 scientists classified and named the soils in the survey area, they compared the 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 Custom Soil Resource Report 6 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 7 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. 8 9 Custom Soil Resource Report Soil Map 449231044923604492410449246044925104492560449261044926604492710449231044923604492410449246044925104492560449261044926604492710489700 489750 489800 489850 489900 489950 490000 489700 489750 489800 489850 489900 489950 490000 40° 35' 7'' N 105° 7' 18'' W40° 35' 7'' N105° 7' 4'' W40° 34' 53'' N 105° 7' 18'' W40° 34' 53'' N 105° 7' 4'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 100 200 400 600 Feet 0 30 60 120 180 Meters Map Scale: 1:2,100 if printed on A portrait (8.5" x 11") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 16, Sep 2, 2021 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 11, 2018—Aug 12, 2018 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Custom Soil Resource Report 10 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 3 Altvan-Satanta loams, 0 to 3 percent slopes 9.3 44.7% 35 Fort Collins loam, 0 to 3 percent slopes 1.9 9.0% 74 Nunn clay loam, 1 to 3 percent slopes 6.3 30.4% 76 Nunn clay loam, wet, 1 to 3 percent slopes 3.3 16.0% Totals for Area of Interest 20.8 100.0% 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. Custom Soil Resource Report 11 The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, 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 12 Larimer County Area, Colorado 3—Altvan-Satanta loams, 0 to 3 percent slopes Map Unit Setting National map unit symbol: jpw2 Elevation: 5,200 to 6,200 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 Altvan and similar soils:45 percent Satanta and similar soils:30 percent Minor components:25 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Altvan Setting Landform:Terraces, benches Landform position (three-dimensional):Side slope, tread Down-slope shape:Linear Across-slope shape:Linear Parent material:Mixed alluvium Typical profile H1 - 0 to 10 inches: loam H2 - 10 to 18 inches: clay loam H3 - 18 to 30 inches: loam H4 - 30 to 60 inches: gravelly sand Properties and qualities Slope:0 to 3 percent Depth to restrictive feature:More than 80 inches Drainage class:Well drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat):Moderately high to high (0.60 to 2.00 in/hr) Depth to water table:More than 80 inches Frequency of flooding:None Frequency of ponding:None Calcium carbonate, maximum content:10 percent Available water supply, 0 to 60 inches: Low (about 5.4 inches) Interpretive groups Land capability classification (irrigated): 3e Land capability classification (nonirrigated): 3e Hydrologic Soil Group: B Ecological site: R067BY002CO - Loamy Plains Hydric soil rating: No Custom Soil Resource Report 13 Description of Satanta Setting Landform:Structural benches, terraces Landform position (three-dimensional):Side slope, tread Down-slope shape:Linear Across-slope shape:Linear Parent material:Mixed alluvium and/or eolian deposits Typical profile H1 - 0 to 9 inches: loam H2 - 9 to 18 inches: loam H3 - 18 to 60 inches: loam Properties and qualities Slope:0 to 1 percent Depth to restrictive feature:More than 80 inches Drainage class:Well drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat):Moderately high to high (0.60 to 2.00 in/hr) Depth to water table:More than 80 inches Frequency of flooding:None Frequency of ponding:None Calcium carbonate, maximum content:10 percent Available water supply, 0 to 60 inches: High (about 10.1 inches) Interpretive groups Land capability classification (irrigated): 1 Land capability classification (nonirrigated): 3c Hydrologic Soil Group: B Ecological site: R067BY002CO - Loamy Plains Hydric soil rating: No Minor Components Nunn Percent of map unit:10 percent Ecological site:R067BZ902CO - Loamy Plains Hydric soil rating: No Larim Percent of map unit:10 percent Ecological site:R067BY063CO - Gravel Breaks Hydric soil rating: No Stoneham Percent of map unit:5 percent Ecological site:R067BZ902CO - Loamy Plains Hydric soil rating: No Custom Soil Resource Report 14 35—Fort Collins loam, 0 to 3 percent slopes Map Unit Setting National map unit symbol: 2tlnc Elevation: 4,020 to 6,730 feet Mean annual precipitation: 14 to 16 inches Mean annual air temperature: 46 to 48 degrees F Frost-free period: 135 to 160 days Farmland classification: Prime farmland if irrigated Map Unit Composition Fort collins and similar soils:85 percent Minor components:15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Fort Collins Setting Landform:Interfluves, stream terraces Landform position (three-dimensional):Interfluve, tread Down-slope shape:Linear Across-slope shape:Linear Parent material:Pleistocene or older alluvium and/or eolian deposits Typical profile Ap - 0 to 4 inches: loam Bt1 - 4 to 9 inches: clay loam Bt2 - 9 to 16 inches: clay loam Bk1 - 16 to 29 inches: loam Bk2 - 29 to 80 inches: loam Properties and qualities Slope:0 to 3 percent Depth to restrictive feature:More than 80 inches Drainage class:Well drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat):Moderately high to high (0.20 to 2.00 in/hr) Depth to water table:More than 80 inches Frequency of flooding:None Frequency of ponding:None Calcium carbonate, maximum content:12 percent Maximum salinity:Nonsaline to very slightly saline (0.1 to 2.0 mmhos/cm) Available water supply, 0 to 60 inches: High (about 9.1 inches) Interpretive groups Land capability classification (irrigated): 3e Land capability classification (nonirrigated): 3e Hydrologic Soil Group: C Custom Soil Resource Report 15 Ecological site: R067BY002CO - Loamy Plains Hydric soil rating: No Minor Components Nunn Percent of map unit:10 percent Landform:Stream terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Ecological site:R067BY002CO - Loamy Plains Hydric soil rating: No Vona Percent of map unit:5 percent Landform:Interfluves Landform position (three-dimensional):Side slope, interfluve Down-slope shape:Linear Across-slope shape:Linear Ecological site:R067BY024CO - Sandy Plains Hydric soil rating: No 74—Nunn clay loam, 1 to 3 percent slopes Map Unit Setting National map unit symbol: 2tlpl Elevation: 3,900 to 5,840 feet Mean annual precipitation: 13 to 17 inches Mean annual air temperature: 50 to 54 degrees F Frost-free period: 135 to 160 days Farmland classification: Prime farmland if irrigated Map Unit Composition Nunn and similar soils:85 percent Minor components:15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Nunn Setting Landform:Terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Parent material:Pleistocene aged alluvium and/or eolian deposits Typical profile Ap - 0 to 9 inches: clay loam Bt - 9 to 13 inches: clay loam Btk - 13 to 25 inches: clay loam Custom Soil Resource Report 16 Bk1 - 25 to 38 inches: clay loam Bk2 - 38 to 80 inches: clay loam Properties and qualities Slope:1 to 3 percent Depth to restrictive feature:More than 80 inches Drainage class:Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat):Moderately low to moderately high (0.06 to 0.20 in/hr) Depth to water table:More than 80 inches Frequency of flooding:None Frequency of ponding:None Calcium carbonate, maximum content:7 percent Maximum salinity:Nonsaline to very slightly saline (0.1 to 2.0 mmhos/cm) Sodium adsorption ratio, maximum:0.5 Available water supply, 0 to 60 inches: High (about 9.9 inches) Interpretive groups Land capability classification (irrigated): 2e Land capability classification (nonirrigated): 3e Hydrologic Soil Group: C Ecological site: R067BY042CO - Clayey Plains Hydric soil rating: No Minor Components Heldt Percent of map unit:10 percent Landform:Terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Ecological site:R067BY042CO - Clayey Plains Hydric soil rating: No Satanta Percent of map unit:5 percent Landform:Terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Ecological site:R067BY002CO - Loamy Plains Hydric soil rating: No 76—Nunn clay loam, wet, 1 to 3 percent slopes Map Unit Setting National map unit symbol: jpxq Elevation: 4,800 to 5,600 feet Mean annual precipitation: 13 to 15 inches Custom Soil Resource Report 17 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 Nunn, wet, and similar soils:90 percent Minor components:10 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Nunn, Wet Setting Landform:Stream terraces, alluvial fans Landform position (three-dimensional):Base slope, tread Down-slope shape:Linear Across-slope shape:Linear Parent material:Alluvium Typical profile H1 - 0 to 10 inches: clay loam H2 - 10 to 47 inches: clay H3 - 47 to 60 inches: gravelly loam Properties and qualities Slope:1 to 3 percent Depth to restrictive feature:More than 80 inches Drainage class:Somewhat poorly drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat):Moderately low to moderately high (0.06 to 0.60 in/hr) Depth to water table:About 24 to 36 inches Frequency of flooding:NoneRare Frequency of ponding:None Calcium carbonate, maximum content:10 percent Maximum salinity:Nonsaline to very slightly saline (0.0 to 2.0 mmhos/cm) Available water supply, 0 to 60 inches: High (about 9.9 inches) Interpretive groups Land capability classification (irrigated): 2w Land capability classification (nonirrigated): 3s Hydrologic Soil Group: C Ecological site: R067BZ902CO - Loamy Plains Hydric soil rating: No Minor Components Heldt Percent of map unit:6 percent Ecological site:R067BZ902CO - Loamy Plains Hydric soil rating: No Dacono Percent of map unit:3 percent Ecological site:R067BY042CO - Clayey Plains Hydric soil rating: No Mollic halaquepts Percent of map unit:1 percent Custom Soil Resource Report 18 Landform:Swales Hydric soil rating: Yes Custom Soil Resource Report 19 Soil Information for All Uses Soil Properties and Qualities The Soil Properties and Qualities section includes various soil properties and qualities displayed as thematic maps with a summary table for the soil map units in the selected area of interest. A single value or rating for each map unit is generated by aggregating the interpretive ratings of individual map unit components. This aggregation process is defined for each property or quality. Soil Erosion Factors Soil Erosion Factors are soil properties and interpretations used in evaluating the soil for potential erosion. Example soil erosion factors can include K factor for the whole soil or on a rock free basis, T factor, wind erodibility group and wind erodibility index. K Factor, Whole Soil Erosion factor K indicates the susceptibility of a soil to sheet and rill erosion by water. Factor K is one of six factors used in the Universal Soil Loss Equation (USLE) and the Revised Universal Soil Loss Equation (RUSLE) to predict the average annual rate of soil loss by sheet and rill erosion in tons per acre per year. The estimates are based primarily on percentage of silt, sand, and organic matter and on soil structure and saturated hydraulic conductivity (Ksat). Values of K range from 0.02 to 0.69. Other factors being equal, the higher the value, the more susceptible the soil is to sheet and rill erosion by water. "Erosion factor Kw (whole soil)" indicates the erodibility of the whole soil. The estimates are modified by the presence of rock fragments. Factor K does not apply to organic horizons and is not reported for those layers. 20 21 Custom Soil Resource Report Map—K Factor, Whole Soil 449231044923604492410449246044925104492560449261044926604492710449231044923604492410449246044925104492560449261044926604492710489700 489750 489800 489850 489900 489950 490000 489700 489750 489800 489850 489900 489950 490000 40° 35' 7'' N 105° 7' 18'' W40° 35' 7'' N105° 7' 4'' W40° 34' 53'' N 105° 7' 18'' W40° 34' 53'' N 105° 7' 4'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 100 200 400 600 Feet 0 30 60 120 180 Meters Map Scale: 1:2,100 if printed on A portrait (8.5" x 11") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Rating Polygons .02 .05 .10 .15 .17 .20 .24 .28 .32 .37 .43 .49 .55 .64 Not rated or not available Soil Rating Lines .02 .05 .10 .15 .17 .20 .24 .28 .32 .37 .43 .49 .55 .64 Not rated or not available Soil Rating Points .02 .05 .10 .15 .17 .20 .24 .28 .32 .37 .43 .49 .55 .64 Not rated or not available Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 16, Sep 2, 2021 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 11, 2018—Aug 12, 2018 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Custom Soil Resource Report 22 Table—K Factor, Whole Soil Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 3 Altvan-Satanta loams, 0 to 3 percent slopes .28 9.3 44.7% 35 Fort Collins loam, 0 to 3 percent slopes .43 1.9 9.0% 74 Nunn clay loam, 1 to 3 percent slopes .28 6.3 30.4% 76 Nunn clay loam, wet, 1 to 3 percent slopes .24 3.3 16.0% Totals for Area of Interest 20.8 100.0% Rating Options—K Factor, Whole Soil Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Layer Options (Horizon Aggregation Method): Surface Layer (Not applicable) Soil Qualities and Features Soil qualities are behavior and performance attributes that are not directly measured, but are inferred from observations of dynamic conditions and from soil properties. Example soil qualities include natural drainage, and frost action. Soil features are attributes that are not directly part of the soil. Example soil features include slope and depth to restrictive layer. These features can greatly impact the use and management of the soil. Hydrologic Soil Group Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Custom Soil Resource Report 23 Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Custom Soil Resource Report 24 25 Custom Soil Resource Report Map—Hydrologic Soil Group 449231044923604492410449246044925104492560449261044926604492710449231044923604492410449246044925104492560449261044926604492710489700 489750 489800 489850 489900 489950 490000 489700 489750 489800 489850 489900 489950 490000 40° 35' 7'' N 105° 7' 18'' W40° 35' 7'' N105° 7' 4'' W40° 34' 53'' N 105° 7' 18'' W40° 34' 53'' N 105° 7' 4'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 100 200 400 600 Feet 0 30 60 120 180 Meters Map Scale: 1:2,100 if printed on A portrait (8.5" x 11") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Rating Polygons A A/D B B/D C C/D D Not rated or not available Soil Rating Lines A A/D B B/D C C/D D Not rated or not available Soil Rating Points A A/D B B/D C C/D D Not rated or not available Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 16, Sep 2, 2021 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Aug 11, 2018—Aug 12, 2018 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Custom Soil Resource Report 26 Table—Hydrologic Soil Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 3 Altvan-Satanta loams, 0 to 3 percent slopes B 9.3 44.7% 35 Fort Collins loam, 0 to 3 percent slopes C 1.9 9.0% 74 Nunn clay loam, 1 to 3 percent slopes C 6.3 30.4% 76 Nunn clay loam, wet, 1 to 3 percent slopes C 3.3 16.0% Totals for Area of Interest 20.8 100.0% Rating Options—Hydrologic Soil Group Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Custom Soil Resource Report 27 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 28 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 29 NORTHERNENGINEERING.COM | 970.221.4158 FORT COLLINS | GREELEY PRELIMINARY DRAINAGE REPORT: THE FLATS AT HANSEN FARM APPENDIX APPENDIX E FRMA FIRMETTE PRELIMINARY DRAINAGE REPORT: IMPALA REDEVELOPMENT APPENDIX National Flood Hazard Layer FIRMette 0 500 1,000 1,500 2,000250 Feet Ü SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT SPECIAL FLOOD HAZARD AREAS Without Base Flood Elevation (BFE) Zone A, V, A99 With BFE or DepthZone AE, AO, AH, VE, AR Regulatory Floodway 0.2% Annual Chance Flood Hazard, Areas of 1% annual chance flood with average depth less than one foot or with drainage areas of less than one square mileZone X Future Conditions 1% Annual Chance Flood HazardZone X Area with Reduced Flood Risk due to Levee. See Notes.Zone X Area with Flood Risk due to LeveeZone D NO SCREEN Area of Minimal Flood Hazard Zone X Area of Undetermined Flood HazardZone D Channel, Culvert, or Storm Sewer Levee, Dike, or Floodwall Cross Sections with 1% Annual Chance 17.5 Water Surface Elevation Coastal Transect Coastal Transect Baseline Profile Baseline Hydrographic Feature Base Flood Elevation Line (BFE) Effective LOMRs Limit of Study Jurisdiction Boundary Digital Data Available No Digital Data Available Unmapped This map complies with FEMA's standards for the use of digital flood maps if it is not void as described below. The basemap shown complies with FEMA's basemap accuracy standards The flood hazard information is derived directly from the authoritative NFHL web services provided by FEMA. This map was exported on 3/30/2022 at 2:25 PM and does not reflect changes or amendments subsequent to this date and time. The NFHL and effective information may change or become superseded by new data over time. This map image is void if the one or more of the following map elements do not appear: basemap imagery, flood zone labels, legend, scale bar, map creation date, community identifiers, FIRM panel number, and FIRM effective date. Map images for unmapped and unmodernized areas cannot be used for regulatory purposes. Legend OTHER AREAS OF FLOOD HAZARD OTHER AREAS GENERAL STRUCTURES OTHER FEATURES MAP PANELS 8 B 20.2 The pin displayed on the map is an approximate point selected by the user and does not represent an authoritative property location. 1:6,000 105°7'30"W 40°35'15"N 105°6'53"W 40°34'47"N Basemap: USGS National Map: Orthoimagery: Data refreshed October, 2020 NORTHERNENGINEERING.COM | 970.221.4158 FORT COLLINS | GREELEY PRELIMINARY DRAINAGE REPORT: IMPALA REDEVELOPMENT APPENDIX MAP POCKET IMPV – IMPERVIOUS AREA EXHIBIT HILL CREST PUD EXHIBIT POND SIZING EXHIBIT C 500 – HISTORIC DRAINAGE EXHIBIT C 501 – DRAINAGE EXHIBIT XXXX X XXXTXXXXXGGEESTWSS9 IRRIRRIRRSWF XXTXXXXXGGEEST9 CCCCCIRRIRRIRRSWF ROOFTOPCONCRETEASPHALTGRAVELSURFACEAREA (SF)% IMPERV.IMPERV.AREA (SF)5,2714,2496,115090%100%100%50%0TOTALS63,68715,108TOTAL=EXISTINGPROPOSEDP:\1914-001\DWG\DRNG\1914-001_IMPV.DWG IMPALA REDEVELOPMENTFORT COLLINS COLORADODESCRIPTIONEXISTING VS. PROPOSEDIMPERVIOUS AREADRAWN BYC. UngermanDATEAPRIL 12, 2022PROJECT1914-001DR-A1DRAWINGSCALE1" = 50'ARTIFICIALTURF050%04,744LANDSCAPE48,0522%9614,2496,115ROOFTOPCONCRETEASPHALTGRAVELSURFACEAREA (SF)% IMPERV.IMPERV.AREA (SF)8,5635,4936,121090%100%100%50%0TOTALS63,68720,191TOTAL=ARTIFICIALTURF050%07,706LANDSCAPE43,9682%8705,4936,1215,173NET CHANGE FROM EXISTING= XXXXXXXXXXXXXXXXXXXXXXXXXX X X X DDDSTSTSTSTSTSTSTSTSTSTSTSTSTSTSTSTSTSTXXXXXXXXX X 42 8 9 7 XXXXXXOS1102200OS2101OS3100101OS1102UD200OS3OS4OS2EXISTING 10'EASEMENTIMPALA CIRCLESOUTH IMPALA DRIVEWEST MULBERRY STREETIMPALA CIRCLEOLIVE STREETDETENTIONPOND 2RAINGARDEN 1DETENTIONPOND 1EXISTING 36"STORM DRAINEXISTING 15"STORM DRAINPROPOSED 6'CONCRETE PANPROPOSED 2'CONCRETE PANPROPOSED OUTLETSTRUCTUREEXISTING 2'CONCRETE PANPROPOSED 2'SIDEWALK CULVERTPROPOSEDRIPRAP RUNDOWNPROPOSEDSTORM DRAINPROPOSED 4'CONCRETE RUNDOWNAND FORBAYPROPOSEDSTORM DRAINPROPOSED STORMDRAINOS4PROPOSED 2'CONCRETE PAN100EXISTINGHEADWALLEXISTINGHEADWALLOS5OS55088 (NAVD88)5087 (NAVD88)5086 (NAVD88) 5085 (NAVD88) 5084 (NAVD88) 5083 (NAVD88) 5082 (NAVD88) 5081 (NAVD88) 5080 (NAVD88)CITY OF FORT COLLINS100-YR FLOODWAYCITY OF FORT COLLINS100-YR HIGH-RISKFLOOD FRINGECITY OF FORT COLLINS100-YR HIGH-RISKFLOOD FRINGEX-SEC #2303 - 5085.14' (NAVD88) X-SEC #1983 - 5081.71' (NAVD88)PROPOSEDWATERQUALITYHEADWALLPROPOSEDOVERFLOWWEIRC 501DRAINAGE EXHIBIT18CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOUDIG, GRADE, OR EXCAVATE FOR THE MARKING OFUNDERGROUND MEMBER UTILITIES.CALL UTILITY NOTIFICATION CENTER OFCOLORADOKnow what'sbelow.before you dig.CallRNORTH( IN FEET )1 inch = ft.Feet0505050100150PROPOSED CONTOURPROPOSED STORM SEWERPROPOSED SWALEEXISTING CONTOURPROPOSED CURB & GUTTERPROPERTY BOUNDARYPROPOSED INLETADESIGN POINTFLOW ARROWDRAINAGE BASIN LABELDRAINAGE BASIN BOUNDARYPROPOSED SWALE SECTION11NOTES:1.REFER TO THE PRELIMINARY DRAINAGE REPORT, DATED OCTOBER 19, 2022 BYNORTHERN ENGINEERING FOR ADDITIONAL INFORMATION.2.THE DEVELOPER SHALL OBTAIN A FLOODPLAIN USE PERMIT FROM THE CITY OFFORT COLLINS AND PAY ALL APPLICABLE FLOODPLAIN USE PERMIT FEES PRIOR TOCOMMENCING ANY CONSTRUCTION ACTIVITY (BUILDING OF STRUCTURES,GRADING, FILL, DETENTION, PONDS, BIKE PATHS, PARKING LOTS, UTILITIES,LANDSCAPED AREAS, FLOOD CONTROL CHANNELS, ETC.) WITHIN THE CANALIMPORTATION FLOODPLAIN AND FLOODWAY. ALL ACTIVITIES WITHIN THEFLOODPLAIN ARE SUBJECT TO THE REQUIREMENTS OF CHAPTER 10 OF THE FORTCOLLINS MUNICIPAL CODE.3.CONSTRUCTION OF NEW STRUCTURES, HARD SURFACE PATHS, WALKWAYS,DRIVEWAYS, WALLS, AND PARKING AREAS IS PROHIBITED IN THE FLOODWAYUNLESS NO-RISE CONDITIONS ARE MET, PER SECTION 10-45 OF CITY CODE. ANYCONSTRUCTION ACTIVITIES IN THE REGULATORY FLOODWAY MUST ALSO INCLUDEA NO-RISE CERTIFICATION PREPARED BY A PROFESSIONAL ENGINEER LICENSED INCOLORADO.4.STORAGE OF EQUIPMENT AND MATERIALS (TEMPORARY OR PERMANENT) IS NOTALLOWED IN THE FLOODWAY.ALEGEND:FOR DRAINAGE REVIEW ONLYNOT FOR CONSTRUCTIONSheetIMPALA REDEVELOPMENT 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 CO N S T R U C T I O N REVIEW SE T of 18Rational Flow Summary | Developed Basin Flow RatesBASINIDTOTAL AREA(acres)Tc2(min)Tc100(min)C2C100Q2(cfs)Q100(cfs)1002.565.05.00.730.795.3420.161010.845.05.00.310.390.743.231021.955.05.00.630.793.5015.262001.995.05.00.430.542.4410.65OS10.205.05.00.790.990.461.99OS24.9313.913.90.250.312.4010.50OS30.0410.210.20.250.310.020.09OS40.295.05.00.650.810.532.32OS50.015.05.00.951.000.040.13XXXXXXXXXXXXXXXXXXXXXXXXXX X X X DDSTSTSTSTSTSTSTSTSTSTSTSTSTSTSTSTSTXXXXXXXXX X 42 8 9 7 B B B B BBBBBBBBBBBBBB B B B BBB BBBBBBBB B B B B B BBBBBBBBBBBBBBBBBBBBBBB B BBBBBBBBBBBBBBBBBBBB B B BB XXXXXXOS1102200OS2101OS3100101OS1102UDTTTEE EVAULTELEC200OS3OS4OS2EXISTING 10'EASEMENTIMPALA CIRCLESOUTH IMPALA DRIVEWEST MULBERRY STREETIMPALA CIRCLEOLIVE STREETDETENTIONPOND 2RAINGARDEN 1DETENTIONPOND 1EXISTING 36"STORM DRAINEXISTING 15"STORM DRAINPROPOSED 6'CONCRETE PANPROPOSED 2'CONCRETE PANPROPOSED OUTLETSTRUCTUREEXISTING 2'CONCRETE PANPROPOSED 2'SIDEWALK CULVERTPROPOSEDRIPRAP RUNDOWNPROPOSEDSTORM DRAINPROPOSED 4'CONCRETE RUNDOWNAND FORBAYPROPOSEDSTORM DRAINPROPOSEDSTORM DRAINPROPOSED STORMDRAINOS4PROPOSED 2'CONCRETE PAN100EXISTINGHEADWALLEXISTINGHEADWALLOS5OS55088 (NAVD88)5087 (NAVD88)5086 (NAVD88) 5085 (NAVD88) 5084 (NAVD88) 5083 (NAVD88) 5082 (NAVD88) 5081 (NAVD88) 5080 (NAVD88)CITY OF FORT COLLINS100-YR FLOODWAYCITY OF FORT COLLINS100-YR HIGH-RISKFLOOD FRINGECITY OF FORT COLLINS100-YR HIGH-RISKFLOOD FRINGEX-SEC #2303 - 5085.14' (NAVD88) X-SEC #1983 - 5081.71' (NAVD88)PROPOSEDWATERQUALITYHEADWALLPROPOSEDOVERFLOWWEIRHEADWALLRELOCATED WITHSAME RELEASERATE (4.50 CFS) ATLOWER ELEVATIONPond No :11100-yr0.915.00 min14203ft32.56 acres0.33ac-ftMax Release Rate =2.80 cfsA =Tc =Project Location :Design PointC =Design StormDETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDFInput VariablesResultsRequired Detention Volume IncreaseFort Collins, CO1914-001Impala RedevelopmentProject Number :Project Name :Pond No :21100-yr1.005.00 min1338ft30.12 acres 0.03ac-ftMax Release Rate =0.04 cfsA =Tc =Project Location :Design PointC =Design StormDETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDFInput VariablesResultsRequired Detention Volume IncreaseFort Collins, CO1914-001Impala Housing CatalystProject Number :Project Name :XXTXXXGGEEST9 CCCCCIRRIRRIRRSWF ROOFTOPCONCRETEASPHALTGRAVELSURFACEAREA (SF)% IMPERV.IMPERV.AREA (SF)8,5635,4936,121090%100%100%50%0TOTALS63,68720,191TOTAL=ARTIFICIALTURF050%07,706LANDSCAPE43,9682%8705,4936,1215,173NET CHANGE FROM EXISTING=5.79 CFS - 4.50 CFS = 1.29 CFS0.12 ACRES / 4.42 ACRES = 3 %3 % of 1.29 CFS = 0.04 CFS XXX XXXXXX XX X XXX XXX X X X X X X XXXXXXXXXXXXXXXXXXXXXWW WW WWWWWWWWWWWWWWWWWWWWWWWWWW WWWWWWWWWWWWWWWWWWWWWWWWWWWWWW WW WWWWWWWWWWWWWWWWWWWW WW WWWWWWWWWW WWWWWWWWWW WWWWIRRIRRIRR IRR IRR IRR IRR IRR D D D ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST ST STSTXXXXXXXXXXTTTTT45088 (NAVD88)28975087 (NAVD88)5086 (NAVD88)5085 (NAVD88)5084 (NAVD88)5083 (NAVD88)5082 (NAVD88)5081 (NAVD88)5080 (NAVD88)POND 1 POND 2 100 101 OS1 IMPALA CIRCLE SOUTH IMPALA DRIVEWEST MULBERRY STREET IMPALA CIRCLE OLIVE STREET EXISTING 15" STORM DRAIN EXISTING 36" STORM DRAIN EXISTING 2' CONCRETE PAN EXISTING HEADWALL & OVERFLOW WEIR EXISTING HEADWALL & OVERFLOW WEIR CITY OF FORT COLLINS 100-YR FLOODWAY CITY OF FORT COLLINS 100-YR HIGH-RISK FLOOD FRINGE CITY OF FORT COLLINS 100-YR HIGH-RISK FLOOD FRINGE OS1 200 OS2 100 OS4 102 101 OS3 X-SEC #2303 - 5085.14' (NAVD88)X-SEC #1983 - 5081.71' (NAVD88)C 500DRAINAGE EXHIBITHISTORIC17 CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UTILITIES. CALL UTILITY NOTIFICATION CENTER OF COLORADO Know what'sbelow. before you dig.Call R NORTH ( IN FEET ) 1 inch = ft. Feet05050 50 100 150 PROPOSED CONTOUR PROPOSED STORM SEWER PROPOSED SWALE EXISTING CONTOUR PROPOSED CURB & GUTTER PROPERTY BOUNDARY PROPOSED INLET A DESIGN POINT FLOW ARROW DRAINAGE BASIN LABEL DRAINAGE BASIN BOUNDARY PROPOSED SWALE SECTION 11 NOTES: 1.REFER TO THE PRELIMINARY DRAINAGE REPORT, DATED OCTOBER 19, 2022 BY NORTHERN ENGINEERING FOR ADDITIONAL INFORMATION. 2.THE DEVELOPER SHALL OBTAIN A FLOODPLAIN USE PERMIT FROM THE CITY OF FORT COLLINS AND PAY ALL APPLICABLE FLOODPLAIN USE PERMIT FEES PRIOR TO COMMENCING ANY CONSTRUCTION ACTIVITY (BUILDING OF STRUCTURES, GRADING, FILL, DETENTION, PONDS, BIKE PATHS, PARKING LOTS, UTILITIES, LANDSCAPED AREAS, FLOOD CONTROL CHANNELS, ETC.) WITHIN THE CANAL IMPORTATION FLOODPLAIN AND FLOODWAY. ALL ACTIVITIES WITHIN THE FLOODPLAIN ARE SUBJECT TO THE REQUIREMENTS OF CHAPTER 10 OF THE FORT COLLINS MUNICIPAL CODE. 3.CONSTRUCTION OF NEW STRUCTURES, HARD SURFACE PATHS, WALKWAYS, DRIVEWAYS, WALLS, AND PARKING AREAS IS PROHIBITED IN THE FLOODWAY UNLESS NO-RISE CONDITIONS ARE MET, PER SECTION 10-45 OF CITY CODE. ANY CONSTRUCTION ACTIVITIES IN THE REGULATORY FLOODWAY MUST ALSO INCLUDE A NO-RISE CERTIFICATION PREPARED BY A PROFESSIONAL ENGINEER LICENSED IN COLORADO. 4.STORAGE OF EQUIPMENT AND MATERIALS (TEMPORARY OR PERMANENT) IS NOT ALLOWED IN THE FLOODWAY. A LEGEND: FOR DRAINAGE REVIEW ONLY NOT FOR CONSTRUCTION SheetIMPALA REDEVELOPMENTThese drawings areinstruments of serviceprovided by NorthernEngineering Services, Inc.and are not to be used forany type of constructionunless signed and sealed bya Professional Engineer inthe employ of NorthernEngineering Services, Inc.NOT FOR CONSTRUCTIONREVIEW SETof 18 Rainfall Intensity: 100 100 2.42 5.0 5.0 0.65 0.71 2.85 4.87 7.00 4.48 7.66 12.03 101 102 0.84 5.0 5.0 0.31 0.37 2.85 4.87 7.00 0.74 1.27 2.17 102 200 1.95 5.0 5.0 0.63 0.69 2.85 4.87 7.00 3.50 5.98 9.41 200 200 1.99 5.0 5.0 0.39 0.45 2.85 2.85 7.00 2.21 2.21 6.27 os1 OS1 0.36 10.4 10.4 0.49 0.55 2.21 2.21 6.80 0.39 0.39 1.34 os2 OS2 4.93 13.9 13.9 0.25 0.31 1.95 1.95 6.24 2.40 2.40 9.54 os3 OS3 0.34 7.6 7.6 0.47 0.53 2.46 2.46 6.94 0.40 0.40 1.26 os4 OS4 0.29 5.0 5.0 0.65 0.70 2.85 2.85 7.00 0.53 0.53 1.41 Tc100 (min) Intensity, i2 (in/hr) Intensity, i100 (in/hr) Offsite Basins Design Point Basin(s)Area, A (acres) Tc2 (min) Flow, Q2 (cfs) Flow, Q100 (cfs) C2 C100 IDF Table for Rational Method - Table 3.4-1 FCSCM Intensity, i10 (in/hr) Flow, Q10 (cfs) HISTORIC RUNOFF COMPUTATIONS XXXXXXXXXXXXXXXXXXXXXXXXXX X X X DDDSTSTSTSTSTSTSTSTSTSTSTSTSTSTSTSTSTSTXXXXXXXXX X 42 8 9 7 XXXXXXOS1102200OS2101OS3100101OS1102UD200OS3OS4OS2EXISTING 10'EASEMENTIMPALA CIRCLESOUTH IMPALA DRIVEWEST MULBERRY STREETIMPALA CIRCLEOLIVE STREETDETENTIONPOND 2RAINGARDEN 1DETENTIONPOND 1EXISTING 36"STORM DRAINEXISTING 15"STORM DRAINPROPOSED 6'CONCRETE PANPROPOSED 2'CONCRETE PANPROPOSED OUTLETSTRUCTUREEXISTING 2'CONCRETE PANPROPOSED 2'SIDEWALK CULVERTPROPOSEDRIPRAP RUNDOWNPROPOSEDSTORM DRAINPROPOSED 4'CONCRETE RUNDOWNAND FORBAYPROPOSEDSTORM DRAINPROPOSED STORMDRAINOS4PROPOSED 2'CONCRETE PAN100EXISTINGHEADWALLEXISTINGHEADWALLOS5OS55088 (NAVD88)5087 (NAVD88)5086 (NAVD88) 5085 (NAVD88) 5084 (NAVD88) 5083 (NAVD88) 5082 (NAVD88) 5081 (NAVD88) 5080 (NAVD88)CITY OF FORT COLLINS100-YR FLOODWAYCITY OF FORT COLLINS100-YR HIGH-RISKFLOOD FRINGECITY OF FORT COLLINS100-YR HIGH-RISKFLOOD FRINGEX-SEC #2303 - 5085.14' (NAVD88) X-SEC #1983 - 5081.71' (NAVD88)PROPOSEDWATERQUALITYHEADWALLPROPOSEDOVERFLOWWEIRC 501DRAINAGE EXHIBIT18CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOUDIG, GRADE, OR EXCAVATE FOR THE MARKING OFUNDERGROUND MEMBER UTILITIES.CALL UTILITY NOTIFICATION CENTER OFCOLORADOKnow what'sbelow.before you dig.CallRNORTH( IN FEET )1 inch = ft.Feet0505050100150PROPOSED CONTOURPROPOSED STORM SEWERPROPOSED SWALEEXISTING CONTOURPROPOSED CURB & GUTTERPROPERTY BOUNDARYPROPOSED INLETADESIGN POINTFLOW ARROWDRAINAGE BASIN LABELDRAINAGE BASIN BOUNDARYPROPOSED SWALE SECTION11NOTES:1.REFER TO THE PRELIMINARY DRAINAGE REPORT, DATED OCTOBER 19, 2022 BYNORTHERN ENGINEERING FOR ADDITIONAL INFORMATION.2.THE DEVELOPER SHALL OBTAIN A FLOODPLAIN USE PERMIT FROM THE CITY OFFORT COLLINS AND PAY ALL APPLICABLE FLOODPLAIN USE PERMIT FEES PRIOR TOCOMMENCING ANY CONSTRUCTION ACTIVITY (BUILDING OF STRUCTURES,GRADING, FILL, DETENTION, PONDS, BIKE PATHS, PARKING LOTS, UTILITIES,LANDSCAPED AREAS, FLOOD CONTROL CHANNELS, ETC.) WITHIN THE CANALIMPORTATION FLOODPLAIN AND FLOODWAY. ALL ACTIVITIES WITHIN THEFLOODPLAIN ARE SUBJECT TO THE REQUIREMENTS OF CHAPTER 10 OF THE FORTCOLLINS MUNICIPAL CODE.3.CONSTRUCTION OF NEW STRUCTURES, HARD SURFACE PATHS, WALKWAYS,DRIVEWAYS, WALLS, AND PARKING AREAS IS PROHIBITED IN THE FLOODWAYUNLESS NO-RISE CONDITIONS ARE MET, PER SECTION 10-45 OF CITY CODE. ANYCONSTRUCTION ACTIVITIES IN THE REGULATORY FLOODWAY MUST ALSO INCLUDEA NO-RISE CERTIFICATION PREPARED BY A PROFESSIONAL ENGINEER LICENSED INCOLORADO.4.STORAGE OF EQUIPMENT AND MATERIALS (TEMPORARY OR PERMANENT) IS NOTALLOWED IN THE FLOODWAY.ALEGEND:FOR DRAINAGE REVIEW ONLYNOT FOR CONSTRUCTIONSheetIMPALA REDEVELOPMENT 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 CO N S T R U C T I O N REVIEW SE T of 18Rational Flow Summary | Developed Basin Flow RatesBASINIDTOTAL AREA(acres)Tc2(min)Tc100(min)C2C100Q2(cfs)Q100(cfs)1002.565.05.00.730.795.3420.161010.845.05.00.310.390.743.231021.955.05.00.630.793.5015.262001.995.05.00.430.542.4410.65OS10.205.05.00.790.990.461.99OS24.9313.913.90.250.312.4010.50OS30.0410.210.20.250.310.020.09OS40.295.05.00.650.810.532.32OS50.015.05.00.951.000.040.13Rainfall Intensity:1001002.565.0 5.0 0.77 0.83 2.85 4.87 9.95 5.63 9.62 21.181011010.845.0 5.0 0.31 0.39 2.85 4.87 9.95 0.74 1.27 3.231021021.955.0 5.0 0.63 0.79 2.85 4.87 9.95 3.50 5.98 15.262002001.995.0 5.0 0.43 0.54 2.85 2.85 9.95 2.44 2.44 10.65os1OS10.205.0 5.0 0.79 0.99 2.85 2.85 9.95 0.46 0.46 1.99os2OS24.9313.9 13.9 0.25 0.31 1.95 1.95 6.82 2.40 2.40 10.50os3OS30.0410.2 10.2 0.25 0.31 2.21 2.21 7.72 0.02 0.02 0.09os4OS40.295.0 5.0 0.65 0.81 2.85 2.85 9.95 0.53 0.53 2.32os5OS50.015.0 5.0 0.95 1.00 2.85 2.85 9.95 0.04 0.04 0.13Tc100(min)Intensity,i2(in/hr)Intensity, i100(in/hr)Offsite Basins DesignPointBasin(s)Area, A(acres)Tc2(min)Flow,Q2(cfs)Flow,Q100(cfs)C2C100IDF Table for Rational Method - Table 3.4-1 FCSCMIntensity,i10(in/hr)Flow,Q10(cfs)DEVELOPED RUNOFF COMPUTATIONS