Loading...
HomeMy WebLinkAboutRENNAT SUBDIVISION - PDP190011 - SUBMITTAL DOCUMENTS - ROUND 2 - DRAINAGE REPORTOctober 18, 2019 PRELIMINARY DRAINAGE AND EROSION CONTROL REPORT FOR RENNAT SUBDIVISION Fort Collins, Colorado Prepared for: JD Padilla Post Modern Development 144 N. Mason St., Suite 4 Ft.Collins, CO 80524 Prepared by: 301 N. Howes, Suite 100 Fort Collins, Colorado 80521 Phone: 970.221.4158 Fax: 970.221.4159 www.northernengineering.com Project Number: 1204-003  This Drainage Report is consciously provided as a PDF. Please consider the environment before printing this document in its entirety. When a hard copy is absolutely necessary, we recommend double-sided printing. October 18, 2019 City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, Colorado 80521 RE: Preliminary Drainage and Erosion Control Report for RENNAT SUBDIVISION Dear Staff: Northern Engineering is pleased to submit this Preliminary Drainage and Erosion Control Report for your review. This report accompanies the Project Development Plan submittal for the proposed Rennat Subdivision development. This report has been prepared in accordance to Fort Collins Stormwater Criteria Manual (FCSCM), and serves to document the stormwater impacts associated with the proposed project. We understand that review by the City is to assure general compliance with standardized criteria contained in the FCSCM. If you should have any questions as you review this report, please feel free to contact us. Sincerely, NORTHERN ENGINEERING SERVICES, INC. Aaron Cvar, PhD, PE Senior Project Engineer Rennat Subdivision Preliminary Drainage Report TABLE OF CONTENTS I. GENERAL LOCATION AND DESCRIPTION ................................................................... 1 A. Location ............................................................................................................................................. 1 B. Description of Property ..................................................................................................................... 2 C. Floodplain.......................................................................................................................................... 4 II. DRAINAGE BASINS AND SUB-BASINS ....................................................................... 4 A. Major Basin Description .................................................................................................................... 4 B. Sub-Basin Description ....................................................................................................................... 4 III. DRAINAGE DESIGN CRITERIA ................................................................................... 5 A. Regulations........................................................................................................................................ 5 B. Four Step Process .............................................................................................................................. 5 C. Development Criteria Reference and Constraints ............................................................................ 6 D. Hydrological Criteria ......................................................................................................................... 6 E. Hydraulic Criteria .............................................................................................................................. 7 F. Modifications of Criteria ................................................................................................................... 7 IV. DRAINAGE FACILITY DESIGN .................................................................................... 8 A. General Concept ............................................................................................................................... 8 B. Specific Details .................................................................................................................................. 9 V. CONCLUSIONS ...................................................................................................... 10 A. Compliance with Standards ............................................................................................................ 10 B. Drainage Concept ............................................................................................................................ 10 APPENDICES: APPENDIX A – Hydrologic Computations and Supporting Documentation APPENDIX B – Water Quality and LID Computations and Information APPENDIX C – Detention Computations, SWMM Output APPENDIX D – Erosion Control Report APPENDIX E – USDA Soils Information Rennat Subdivision Preliminary Drainage Report LIST OF FIGURES: Figure 1 – Aerial Photograph ................................................................................................ 2 Figure 2– Proposed Site Plan ................................................................................................ 3 Figure 3 – Existing Floodplains ............................................................................................. 4 MAP POCKET: Proposed Drainage Exhibit Rennat Subdivision Preliminary Drainage Report 1 I. GENERAL LOCATION AND DESCRIPTION A. Location 1. Vicinity Map 2. The project site is located in the east half of Section 7, Township 6 North, Range 68 West of the 6th Principal Meridian, City of Fort Collins, County of Larimer, State of Colorado. 3. The project site is located just west of the intersection of Timberline Rd. and Rosen Dr. 4. Existing residential developments, Fossil Creek at Linden Park, Crowne at Timberline LP exist to the south of the site; Willow Springs exists to the north of the site. 5. No significant offsite flows enter the site from the north or south. There are existing ridgelines near the northern and southern boundaries of the site. Timberline Road has a high point just northeast of the site and acts as a barrier for any offsite flows from the east. Historic flows convey west towards the existing Union Pacific Railroad embankment and pass under the embankment through an existing large diameter ductile iron pipe. Rennat Subdivision Preliminary Drainage Report 2 B. Description of Property 1. The overall property is 57.83 acres in size; however, the proposed development area is roughly 33.5 acres in size. Figure 1 – Aerial Photograph 2. The subject property is currently composed of undeveloped land. Existing ground slopes are mild to moderate (i.e., 1 - 6±%) through the interior of the property. Historic drainage patterns direct flows generally from north, south and east, and drain via sheet flow collecting within an existing wet pond in the west central portion of the site. 3. Historically, the majority of storm runoff discharges into the existing wet pond located within the west central portion of the site. The proposed development will maintain historic drainage patterns and will provide detention within the upper level of the existing wet pond, as discussed further below. 4. The proposed detention pond will overdetain flows and release below historic rates west to the existing culvert under the Union Pacific Railroad embankment. We propose to restrict peak 100-year discharge from the proposed detention pond to no greater than 5.0 cfs, as discussed below. 5. The proposed site design will include both LID and Extended Detention water quality treatment prior to stormwater discharge from the site. Water quality treatment methods are described in further detail below. 6. According to the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Soil Survey website: PROJECT SITE Rennat Subdivision Preliminary Drainage Report 3 http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx, the site primarily consists of Fort Collins Loam, which falls into Hydrologic Soil Group B, and Aquepts Loam, which falls into Hydrologic Soil Group D. 7. The proposed project site plan is composed of single family, and multi-family residential development Associated site work, water, and sewer lines will be constructed with the development. Onsite detention water quality treatment is proposed and will consist of several features which are discussed in Section IV. Figure 2– Proposed Site Plan 8. The proposed land use is single family and multi-family residential. Rennat Subdivision Preliminary Drainage Report 4 C. Floodplain 1. The project site is not encroached by any FEMA jurisdictional flood zone. Additionally, the site is not encroached by any City designated flood zones, as shown in Figure 3, below. Figure 3 –Area Floodplain Mapping II. DRAINAGE BASINS AND SUB-BASINS A. Major Basin Description 1. The project site lies within the Fossil Creek Master Drainage Basin. Onsite detention is required for the runoff volume difference between the 100-year developed inflow rate and the historic 2-year rate, which is specified in the master plan as 0.20 cfs per acre. 2. We propose to overdetain flows and release below historic rates west to the existing culvert under the Union Pacific Railroad embankment. We propose to restrict peak 100-year discharge from the proposed detention pond to no greater than 5.0 cfs, which is below the allowable release rate per the Fossil Creek master drainage study of 0.20 cfs per acre, which translates to 11.6 cfs for the 57.83 acre site. This reduced release rate is proposed in order to mitigate any potential downstream impacts B. Sub-Basin Description 1. Historically, the majority of storm runoff discharges into the existing wet pond located within the west central portion of the site. Depending on the antecedent water level in the pond, historic flows would overflow from the pond and convey west under the PROJECT SITE Rennat Subdivision Preliminary Drainage Report 5 adjacent Union Pacific railroad embankment through an existing ductile iron pipe with an estimated diameter of 42-inches. From this pipe, the flow path for historic flows conveys storm runoff through the Southridge Golf Course, located just west of the railroad embankment and then into the existing storm system within the Greenridge at Southridge Greens subdivision. Ultimately historic runoff conveys west into Fossil Creek. The proposed development will maintain historic drainage patterns and will provide detention within the upper level of the existing wet pond. 2. A more detailed description of the project drainage patterns is provided below. III. DRAINAGE DESIGN CRITERIA A. Regulations There are no optional provisions outside of the FCSCM proposed with the proposed project. B. Four Step Process The overall stormwater management strategy employed with the proposed project utilizes the “Four Step Process” to minimize adverse impacts of urbanization on receiving waters. The following is a description of how the proposed development has incorporated each step. Step 1 – Employ Runoff Reduction Practices Several techniques have been utilized with the proposed development to facilitate the reduction of runoff peaks, volumes, and pollutant loads as the site is developed from the current use by implementing multiple Low Impact Development (LID) strategies including: Conserving existing amenities in the site including the existing vegetated areas. Providing vegetated open areas throughout the site to reduce the overall impervious area and to minimize directly connected impervious areas (MDCIA). Routing flows, to the extent feasible, through vegetated swales to increase time of concentration, promote infiltration and provide initial water quality. Step 2 – Implement BMPs That Provide a Water Quality Capture Volume (WQCV) with Slow Release The efforts taken in Step 1 will facilitate the reduction of runoff; however, urban development of this intensity will still generate stormwater runoff that will require additional BMPs and water quality. The majority of stormwater runoff from the site will ultimately be intercepted and treated using detention and LID treatment methods prior to exiting the site. Step 3 – Stabilize Drainageways There are no major drainageways within the subject property. While this step may not seem applicable to proposed development, the project indirectly helps achieve stabilized drainageways nonetheless. By providing water quality treatment, where none previously existed, sediment with erosion potential is removed from downstream drainageway systems. Furthermore, this project will pay one-time stormwater development fees, as well as ongoing monthly stormwater utility fees, both of which help achieve City-wide drainageway stability. Step 4 – Implement Site Specific and Other Source Control BMPs. The proposed project will improve upon site specific source controls compared to historic conditions: Rennat Subdivision Preliminary Drainage Report 6 The proposed development will provide LID and water quality treatment; thus, eliminating sources of potential pollution previously left exposed to weathering and runoff processes. C. Development Criteria Reference and Constraints The subject property is surrounded by currently developed properties. Thus, several constraints have been identified during the course of this analysis that will impact the proposed drainage system including: Existing elevations along the property lines will generally be maintained. As previously mentioned, overall drainage patterns of the existing site will be maintained. Elevations of existing downstream facilities that the subject property will release to will be maintained. 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 proposed development. Tabulated data contained in Table 3.4-1 has been utilized for Rational Method runoff calculations. 2. The Rational Method has been employed to compute stormwater runoff utilizing runoff coefficients contained and frequency adjustment factors in Tables 3.2-2 and 3.2-3 of the FCSCM. Table 3.2-2 –Surface Type – Runoff Coefficients (City of Fort Collins Stormwater Criteria Manual, Ref.1) Rennat Subdivision Preliminary Drainage Report 7 Table 3.2-3 –Frequency Adjustment Factors (City of Fort Collins Stormwater Criteria Manual, Ref.1) 3. Three separate design storms have been utilized to address distinct drainage scenarios. A fourth design storm has also been computed for comparison purposes. The first design storm considered is the 80th percentile rain event, which has been employed to design the project’s water quality features. The second event analyzed is the “Minor,” or “Initial” Storm, which has a 2-year recurrence interval. The third event considered is the “Major Storm,” which has a 100-year recurrence interval. The fourth storm computed, for comparison purposes only, is the 10-year event. 4. No other assumptions or calculation methods have been used with this development that are not referenced by current City of Fort Collins criteria. E. Hydraulic Criteria 1. As previously noted, the subject property maintains historic drainage patterns. 2. All drainage facilities proposed with the project are designed in accordance with criteria outlined in the FCSCM and/or the Urban Drainage and Flood Control District (UDFCD) Urban Storm Drainage Criteria Manual. 3. As stated above, the subject property is not located in a FEMA designated floodplain, or within a City designated floodplain and floodway. The proposed project does not propose to modify any natural drainageways. F. Modifications of Criteria 1. The proposed development is not requesting any modifications to criteria at this time. Rennat Subdivision Preliminary Drainage Report 8 IV. DRAINAGE FACILITY DESIGN A. General Concept 1. The main objectives of the project drainage design are to maintain existing drainage patterns, and to ensure no adverse impacts to any adjacent properties. 2. LID and water quality treatment will be provided in the form of forebays, extended detention, and an existing wet pond, as discussed further below. 3. Drainage patterns anticipated for drainage basins shown in the Drainage Exhibit are described below. Drainage basins have been defined for preliminary design purposes and are subject to change at Final design; however, general drainage patterns and concepts are not expected to be significantly altered. Basins 1, 6a, 7a Basins 1, 6a, and 7a consist of single family areas, right of way, and open space. Drainage from these basins will be conveyed via street curb and gutter to proposed storm sewer systems, which will direct developed runoff into Rain Garden 1. This rain garden will pre-treat developed runoff prior to discharge into the existing pond located within the central western portion of the site, which will provide detention of developed runoff. Basins 2, 5, 6b, 7b, 12 Basins 2, 5, 6b, 7b, 12 consist of single family areas, right of way, and open space. Drainage from these basins will be conveyed via street curb and gutter to proposed storm sewer systems, which will direct developed runoff into Water Quality Pond 1. This water quality pond will pre-treat developed runoff prior to discharge into the existing pond located within the central western portion of the site, which will provide detention of developed runoff. Basins 3,8,9,13 Basins 3,8,9,13 consist of single family areas, right of way, and open space. Drainage from these basins will be conveyed via street curb and gutter to proposed storm sewer systems which will direct developed runoff into detention Pond 1. This pond will provide attenuation prior to discharge into a main storm line running east- west through the site and discharging into the existing wet pond. No water quality treatment will be provided in this pond; the purpose of the pond is attenuation and downsizing of the main storm line running through the site. Discharge from Pond 1 will be conveyed in the proposed storm sewer system, which will direct developed runoff into Rain Garden 1. This rain garden will pre-treat developed runoff prior to discharge into the existing pond located within the central western portion of the site. Basin 10 Basin 10 consists of frontage of a small portion of single family area and right of way. Drainage from the basin will flow in right of way to offsite right of way to the east. Basin 11a Basin 11a consists of single family fronts of lots, and right of way. Drainage from this basin will be conveyed via street curb and gutter to a proposed sidewalk culvert. This sidewalk culvert will direct developed runoff into Water Quality Pond 2, which will pre-treat developed runoff prior to discharge into the existing pond located within the central western portion of the site. Rennat Subdivision Preliminary Drainage Report 9 Basin 11b Basin 11b consists of backs of lots of a single family area. Drainage from the basin will sheet flow to offsite areas to the south, which is the historic drainage pattern. We will be reducing runoff area, and maintaining the sheet flow character of runoff from this area. Thus, we propose no adverse impact to offsite properties. 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. Standard water quality treatment in the form of Extended Detention is being provided for the overall proposed development within the Water Quality Ponds 1 and 2. We have computed required extended detention volume based on the standard water quality treatment for 50% of site runoff. Please see Water Quality Capture Volume (Extended Detention) computations provided in Appendix B. 2. LID treatment is being provided within Rain Garden 1, which will provide in excess of the required LID treatment of 50% of site runoff. Please see Water Rain Garden computations provided in Appendix B. 3. The overall site drains into the existing wet Pond. The existing pond has a permanent water surface and will provide detention above the this water surface. Existing established wetland vegetation and the permanent water surface will greatly enhance water quality for runoff discharging from the site. Rain Garden 1, Water Quality Pond 1, and Water Quality Pond 2 will be provided for pre-treatment for the majority of developed runoff prior to entry to the existing wetland. 4. Please see Table 1, below, for a detention summary. TABLE 1 – Detention Summary Pond ID 100-Yr. Detention Vol. (Ac-Ft) Water Quality Capture Volume (Ac-Ft) Total Req'd Vol. (Ac-Ft) Peak Release (cfs) Pond 1 1.06 N/A 1.06 12.10 Existing Wet Pond 12.56 0.35 12.56 5.00 Rennat Subdivision Preliminary Drainage Report 10 V. CONCLUSIONS A. Compliance with Standards 1. The drainage design proposed with the proposed project complies with the City of Fort Collins’ Stormwater Criteria Manual. 2. The drainage design proposed with this project complies with requirements for the West Vine Basin Master Plan. 3. The drainage plan and stormwater management measures proposed with the proposed development are compliant with all applicable State and Federal regulations governing stormwater discharge. B. Drainage Concept 1. The drainage design proposed with this project will effectively limit any potential damage associated with its stormwater runoff by providing detention and water quality mitigation features. 2. The drainage concept for the proposed development is consistent with requirements for the West Vine Basin Master Plan. Rennat Subdivision Preliminary Drainage Report 11 References 1. Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, December 2018. 2. Larimer County Urban Area Street Standards, Adopted January 2, 2001, Repealed and Reenacted, Effective October 1, 2002, Repealed and Reenacted, Effective April 1, 2007. 3. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation Service, United States Department of Agriculture (https://websoilsurvey.sc.egov.usda.gov/App/ Data upload February 2019) 4. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control District, Wright-McLaughlin Engineers, Denver, Colorado, Revised April 2008. APPENDIX A Hydrologic Computations and Supporting Documentation CHARACTER OF SURFACE: Runoff Coefficient Percentage Impervious Project: 1204-003 Streets, Parking Lots, Roofs, Alleys, and Drives: Calculations By: ATC Asphalt ……....……………...……….....…...……………….………………………………….. 0.95 100% Date: Concrete …….......……………….….……….………………..….…………………………………0.95 90% Gravel ……….…………………….….…………………………..……………………………….. 0.50 40% Roofs …….…….………………..……………….…………………………………………….. 0.95 90% Pavers…………………………...………………..…………………………………………….. 0.50 40% Lawns and Landscaping Sandy Soil ……..……………..……………….…………………………………………….. 0.15 0% Clayey Soil ….….………….…….…………..………………………………………………. 0.25 0% 2-year Cf = 1.00 100-year Cf = 1.25 Basin ID Basin Area (s.f.) Basin Area (ac) Area of Asphalt (ac) Area of Concrete (ac) Area of Roofs (ac) Area of Gravel (ac) Area of Lawn, Rain Garden, or Landscaping (ac) 2-year Composite Runoff Coefficient 10-year Composite Runoff Coefficient 100-year Composite Runoff Coefficient Composite % Imperv. 1 188833 4.34 1.04 0.22 0.52 0.00 2.56 0.54 0.54 0.67 39% 2 144846 3.33 0.73 0.17 0.40 0.00 2.03 0.52 0.52 0.65 37% 3 188231 4.32 1.43 0.22 0.52 0.00 2.16 0.60 0.60 0.75 48% 4 1041680 23.91 0.00 1.20 2.87 0.00 19.85 0.37 0.37 0.46 15% 5 67037 1.54 0.49 0.08 0.18 0.00 0.78 0.59 0.59 0.74 47% 6a 31730 0.73 0.24 0.04 0.09 0.00 0.36 0.60 0.60 0.75 48% 6b 98339 2.26 0.52 0.11 0.27 0.00 1.35 0.53 0.53 0.66 38% 7a 48046 1.10 0.28 0.06 0.13 0.00 0.64 0.54 0.54 0.68 40% 7b 166889 3.83 0.92 0.19 0.46 0.00 2.26 0.54 0.54 0.67 39% Overland Flow, Time of Concentration: Project: 1204-003 Calculations By: Date: Gutter/Swale Flow, Time of Concentration: Tt = L / 60V Tc = T i + Tt (Equation RO-2) Velocity (Gutter Flow), V = 20·S ½ Velocity (Swale Flow), V = 15·S ½ NOTE: C-value for overland flows over grassy surfaces; C = 0.25 Is Length >500' ? C*Cf (2-yr Cf=1.00) C*Cf (10-yr Cf=1.00) C*Cf (100-yr Cf=1.25) Length, L (ft) Slope, S (%) Ti 2-yr (min) Ti 10-yr (min) Ti 100-yr (min) Length, L (ft) Slope, S (%) Velocity, V (ft/s) Tt (min) Length, L (ft) Slope, S (%) Velocity, V (ft/s) Rational Method Equation: Project: 1204-003 Calculations By: Date: From Section 3.2.1 of the CFCSDDC Rainfall Intensity: 1 1 4.34 14 14 14 0.54 0.54 0.67 1.92 3.29 6.71 4.47 7.66 19.53 2 2 3.33 13 13 13 0.52 0.52 0.65 2.02 3.45 7.04 3.50 5.99 15.30 3 3 4.32 14 14 14 0.60 0.60 0.75 1.95 3.34 6.82 5.06 8.66 22.09 4 4 23.91 11 11 11 0.37 0.37 0.46 2.13 3.63 7.42 18.80 32.03 81.84 5 5 1.54 15 15 15 0.59 0.59 0.74 1.90 3.24 6.62 1.73 2.96 7.55 6a 6a 0.73 11 11 11 0.60 0.60 0.75 2.13 3.63 7.42 0.93 1.59 4.05 6b 6b 2.26 13 13 13 0.53 0.53 0.66 1.98 3.39 6.92 2.37 4.06 10.35 7a 7a 1.10 13 13 13 0.54 0.54 0.68 2.02 3.45 7.04 1.21 2.07 5.28 7b 7b 3.83 14 14 14 0.54 0.54 0.67 1.92 3.29 6.71 3.95 6.77 17.26 8 8 1.72 12 12 12 0.54 0.54 0.67 2.05 3.50 7.16 1.89 3.23 8.27 9 9 1.57 15 15 15 0.57 0.57 0.71 1.90 3.24 6.62 1.68 2.87 7.32 10 10 0.09 6 6 6 0.63 0.63 0.79 2.67 4.56 9.31 0.14 0.25 0.63 11a 11a 2.23 13 13 13 0.60 0.60 0.75 1.98 3.39 6.92 2.65 4.53 11.57 11b 11b 0.95 10 10 10 0.37 0.37 0.46 2.21 3.78 7.72 0.77 1.32 3.37 12 12 3.05 16 16 16 0.52 0.52 0.65 1.84 3.14 6.41 2.94 5.00 12.79 13 13 2.51 13 13 13 0.59 0.59 0.74 1.98 3.39 6.92 2.94 5.04 12.86 OS1 OS1 0.34 13 13 13 0.71 0.71 0.88 1.98 3.39 6.92 0.48 0.82 2.10 Intensity, i10 (in/hr) Rainfall Intensity taken from the City of Fort Collins Storm Drainage Design Criteria (CFCSDDC), Figure 3.1 C10 Area, A (acres) Intensity, i2 (in/hr) 100-yr Tc (min) RUNOFF COMPUTATIONS C100 Design Point Flow, Q100 (cfs) Flow, Q2 (cfs) 10-yr Tc (min) 2-yr Tc (min) C2 Flow, Q10 (cfs) Intensity, i100 (in/hr) Basin(s) ATC FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 3.0 Rational Method 3.2 Runoff Coefficients Page 4 3.2 Runoff Coefficients Runoff coefficients used for the Rational Method are determined based on either overall land use or surface type across the drainage area. For Overall Drainage Plan (ODP) submittals, when surface types may not yet be known, land use shall be used to estimate flow rates and volumes. Table 3.2-1 lists the runoff coefficients for common types of land uses in the City. Table 3.2-1. Zoning Classification - Runoff Coefficients Land Use Runoff Coefficient (C) Residential Urban Estate 0.30 Low Density 0.55 Medium Density 0.65 High Density 0.85 Commercial Commercial 0.85 Industrial 0.95 Undeveloped Open Lands, Transition 0.20 Greenbelts, Agriculture 0.20 Reference: For further guidance regarding zoning classifications, refer to the Land Use Code, Article 4. For a Project Development Plan (PDP) or Final Plan (FP) submittals, runoff coefficients must be based on the proposed land surface types. Since the actual runoff coefficients may be different from those specified in Table 3.2-1, Table 3.2-2 lists coefficients for the specific types of land surfaces. FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 3.0 Rational Method 3.2 Runoff Coefficients Page 5 Table 3.2-2. Surface Type - Runoff Coefficients Surface Type Runoff Coefficients Hardscape or Hard Surface Asphalt, Concrete 0.95 Rooftop 0.95 Recycled Asphalt 0.80 Gravel 0.50 Pavers 0.50 Landscape or Pervious Surface Lawns, Sandy Soil, Flat Slope < 2% 0.10 Lawns, Sandy Soil, Avg Slope 2-7% 0.15 Lawns, Sandy Soil, Steep Slope >7% 0.20 Lawns, Clayey Soil, Flat Slope < 2% 0.20 Lawns, Clayey Soil, Avg Slope 2-7% 0.25 Lawns, Clayey Soil, Steep Slope >7% 0.35 3.2.1 Composite Runoff Coefficients Drainage sub-basins are frequently composed of land that has multiple surface types or zoning classifications. In such cases a composite runoff coefficient must be calculated for any given drainage sub-basin. The composite runoff coefficient is obtained using the following formula: ( ) t n i i i A C xA C ∑ = = 1 Equation 5-2 Where: C = Composite Runoff Coefficient Ci = Runoff Coefficient for Specific Area (Ai), dimensionless Ai = Area of Surface with Runoff Coefficient of Ci, acres or square feet n = Number of different surfaces to be considered At = Total Area over which C is applicable, acres or square feet 3.2.2 Runoff Coefficient Frequency Adjustment Factor The runoff coefficients provided in Table 3.2-1 and Table 3.2-2 are appropriate for use with the 2-year storm event. For any analysis of storms with higher intensities, an adjustment of the runoff coefficient is required due to the lessening amount of infiltration, depression retention, evapotranspiration and other losses that have a proportionally smaller effect on high-intensity storm runoff. This adjustment is FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 3.0 Rational Method 3.3 Time of Concentration Page 6 applied to the composite runoff coefficient. These frequency adjustment factors, Cf, are found in Table 3.2-3. Table 3.2-3. Frequency Adjustment Factors Storm Return Period (years) Frequency Adjustment Factor (Cf) 2, 5, 10 1.00 25 1.10 50 1.20 100 1.25 3.3 Time of Concentration 3.3.1 Overall Equation The next step to approximate runoff using the Rational Method is to estimate the Time of Concentration, Tc, or the time for water to flow from the most remote part of the drainage sub-basin to the design point under consideration. The Time of Concentration is represented by the following equation: 𝐓𝐓𝐜𝐜 = 𝐓𝐓 𝐢𝐢 + 𝐓𝐓𝐭𝐭 Equation 5-3 Where: Tc = Total Time of Concentration, minutes Ti = Initial or Overland Flow Time of Concentration, minutes Tt = Channelized Flow in Swale, Gutter or Pipe, minutes 3.3.2 Overland Flow Time Overland flow, Ti, can be determined by the following equation: 𝐓𝐓𝐢𝐢 = 𝟏𝟏.𝟖𝟖𝟖𝟖(𝟏𝟏.𝟏𝟏−𝐂𝐂𝐂𝐂𝐂𝐂𝐟𝐟)√𝐋𝐋 √𝐒𝐒 𝟑𝟑 Equation 3.3-2 Where: C = Runoff Coefficient, dimensionless Cf = Frequency Adjustment Factor, dimensionless L = Length of Overland Flow, feet S = Slope, percent CXCF PRODUCT OF CXCF CANNOT EXCEED THE VALUE OF 1 OVERLAND FLOW LENGTH L=200’ MAX IN DEVELOPED AREAS L=500’ MAX IN UNDEVELOPED AREAS FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 3.0 Rational Method 3.4 Intensity-Duration-Frequency Curves for Rational Method Page 7 3.3.3 Channelized Flow Time Travel time in a swale, gutter or storm pipe is considered “channelized” or “concentrated” flow and can be estimated using the Manning’s Equation: 𝐕𝐕 = 𝟏𝟏.𝟒𝟒𝟒𝟒 𝐧𝐧 𝐑𝐑𝟐𝟐/𝟑𝟑 𝐒𝐒𝟏𝟏/𝟐𝟐 Equation 5-4 Where: V = Velocity, feet/second n = Roughness Coefficient, dimensionless R = Hydraulic Radius, feet (Hydraulic Radius = area / wetted perimeter, feet) S = Longitudinal Slope, feet/feet And: 𝐓𝐓𝐭𝐭 = 𝐋𝐋 𝐕𝐕𝐂𝐂𝐕𝐕𝐕𝐕 Equation 5-5 3.3.4 Total Time of Concentration A minimum Tc of 5 minutes is required. The maximum Tc allowed for the most upstream design point shall be calculated using the following equation: 𝐓𝐓𝐜𝐜 = 𝐋𝐋 𝟏𝟏𝟖𝟖𝐕𝐕 + 𝟏𝟏𝐕𝐕 Equation 3.3-5 The Total Time of Concentration, Tc, is the lesser of the values of Tc calculated using Tc = Ti + Tt or the equation listed above. 3.4 Intensity-Duration-Frequency Curves for Rational Method The two-hour rainfall Intensity-Duration-Frequency curves for use with the Rational Method is provided in Table 3.4-1 and Figure 3.4-1. TC • A MINIMUM TC OF 5 MINUTES IS REQUIRED IN ALL CASES. • A MAXIMUM TC OF 5 MINUTES IS TYPICAL FOR SMALLER, URBAN PROJECTS. FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 3.0 Rational Method 3.4 Intensity-Duration-Frequency Curves for Rational Method Page 8 Table 3.4-1. IDF Table for Rational Method Duration (min) Intensity 2-year (in/hr) Intensity 10-year (in/hr) Intensity 100-year (in/hr) Duration (min) Intensity 2-year (in/hr) Intensity 10-year (in/hr) Intensity 100-year (in/hr) 5 2.85 4.87 9.95 39 1.09 1.86 3.8 6 2.67 4.56 9.31 40 1.07 1.83 3.74 7 2.52 4.31 8.80 41 1.05 1.80 3.68 8 2.40 4.10 8.38 42 1.04 1.77 3.62 9 2.30 3.93 8.03 43 1.02 1.74 3.56 10 2.21 3.78 7.72 44 1.01 1.72 3.51 11 2.13 3.63 7.42 45 0.99 1.69 3.46 12 2.05 3.50 7.16 46 0.98 1.67 3.41 13 1.98 3.39 6.92 47 0.96 1.64 3.36 14 1.92 3.29 6.71 48 0.95 1.62 3.31 15 1.87 3.19 6.52 49 0.94 1.6 3.27 16 1.81 3.08 6.30 50 0.92 1.58 3.23 17 1.75 2.99 6.10 51 0.91 1.56 3.18 18 1.70 2.90 5.92 52 0.9 1.54 3.14 19 1.65 2.82 5.75 53 0.89 1.52 3.10 20 1.61 2.74 5.60 54 0.88 1.50 3.07 21 1.56 2.67 5.46 FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 3.0 Rational Method 3.4 Intensity-Duration-Frequency Curves for Rational Method Page 9 Figure 3.4-1. Rainfall IDF Curve – Fort Collins APPENDIX B Water Quality and LID Computations and Information Project Number: Project: Rennat Project Location: Calculations By: Date: 10/18/2019 Sq. Ft. Acres LID 1 266,074 6.11 61% 1, 4b Grass-Lined Swale 126,754 LID 2 813,147 18.67 71% 2, 3, 4c, 5a, 6a,7a, 8, 9, 13, OS1 Rain Garden 1 15,158 574,768 Total 1,079,220 24.78 701,522 2,532,032 ft 2 1,125,297 ft 2 388,244 ft 2 562,649 ft 2 701,522 ft 2 62.34% 50% Requried Minium Area to be Treated Total Treated Impervious Area Percent Impervious Treated by LID LID Summary per LID Structure LID Site Summary Total Site Area Total Impervious Area Total Impervious Area without LID Treatment Impervious Area (ft 2 ) LID ID Subbasin ID Treatment Type Volume per UD-BMP (ft 3 ) Area Weighted % Impervious 1204-003 Fort Collins, Colorado M. Ruebel LID Summary WATER QUALITY POND DESIGN CALCULATIONS Pond 1 Project: 1204-003 By: ATC Date: 10/18/19 REQUIRED STORAGE & OUTLET WORKS: BASIN AREA = 9.800 <-- INPUT from impervious calcs BASIN IMPERVIOUSNESS PERCENT = 60.00 <-- INPUT from impervious calcs BASIN IMPERVIOUSNESS RATIO = 0.6000 <-- CALCULATED WQCV (watershed inches) = 0.236 <-- CALCULATED from Figure EDB-2 WQCV (ac-ft) = 0.231 <-- CALCULATED from UDFCD DCM V.3 Section 6.5 WQ Depth (ft) = TBD* <-- INPUT from stage-storage table *Basins 4d, 5b, 6b, 7b, 12 *Water Quality Depth to be determined at Final Design WATER QUALITY POND DESIGN CALCULATIONS Pond 2 Project: 1204-003 By: ATC Date: 10/18/19 REQUIRED STORAGE & OUTLET WORKS: BASIN AREA = 2.220 <-- INPUT from impervious calcs BASIN IMPERVIOUSNESS PERCENT = 73.00 <-- INPUT from impervious calcs BASIN IMPERVIOUSNESS RATIO = 0.7300 <-- CALCULATED WQCV (watershed inches) = 0.289 <-- CALCULATED from Figure EDB-2 WQCV (ac-ft) = 0.064 <-- CALCULATED from UDFCD DCM V.3 Section 6.5 WQ Depth (ft) = TBD* <-- INPUT from stage-storage table *Basins 11a *Water Quality Depth to be determined at Final Design Sheet 1 of 2 Designer: Company: Date: Project: Location: 1. Basin Storage Volume A) Effective Imperviousness of Tributary Area, Ia Ia = 71.0 % (100% if all paved and roofed areas upstream of rain garden) B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.710 C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.22 watershed inches (WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i) D) Contributing Watershed Area (including rain garden area) Area = 813,147 sq ft E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = 15,158 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 = cu ft (Only if a different WQCV Design Volume is desired) 2. Basin Geometry A) WQCV Depth (12-inch maximum) DWQCV = 12.00 in B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 4.00 ft / ft (Use "0" if rain garden has vertical walls) C) Mimimum Flat Surface Area AMin = 11547 sq ft D) Actual Flat Surface Area AActual = 16948 sq ft E) Area at Design Depth (Top Surface Area) ATop = 19301 sq ft F) Rain Garden Total Volume VT= 18,125 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 = 2.6 ft Volume to the Center of the Orifice ii) Volume to Drain in 12 Hours Vol12 = 15,158 cu ft iii) Orifice Diameter, 3/8" Minimum DO = 2 2/3 in Design Procedure Form: Rain Garden (RG) M. Ruebel Northern Engineering October 18, 2019 Rennat Fort Collins Choose One Choose One 18" Rain Garden Growing Media Other (Explain): YES NO Rain Garden B.xlsm, RG 10/17/2019, 5:27 PM 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? PROVIDE A 30 MIL (MIN) PVC LINER WITH CDOT CLASS B GEOTEXTILE ABOVE IT. USE THE SAME GEOTEXTILE BELOW THE LINER IF THE SUBGRADE IS ANGULAR 6. Inlet / Outlet Control A) Inlet Control 7. Vegetation 8. Irrigation A) Will the rain garden be irrigated? Notes: See approved landscaping plans for seed mixtures and plantings. Design Procedure Form: Rain Garden (RG) M. Ruebel Northern Engineering October 18, 2019 Rennat Fort Collins 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 Rain Garden B.xlsm, RG 10/17/2019, 5:27 PM 12" W 12" W X SS VAULT ELEC X X X X X IRR WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM UD UD UD E E E E E E E E E E E E E E E E E E E E E E E E E E APPENDIX C Detention Computations, SWMM Output Project: 1204-003 By: ATC Date: 07/25/19 Pond ID 100-Yr. Detention Vol. (Ac-Ft) Water Quality Capture Volume (Ac- Ft) Total Req'd Vol. (Ac-Ft) Peak Release (cfs) Pond 1 1.06 N/A 1.06 12.10 Existing Wet Pond 12.56 0.35 12.56 5.00 POND SUMMARY TABLE EPA STORM WATER MANAGEMENT MODEL - VERSION 5.1 (Build 5.1.012) -------------------------------------------------------------- ********************************************************* NOTE: The summary statistics displayed in this report are based on results found at every computational time step, not just on results from each reporting time step. ********************************************************* **************** Analysis Options **************** Flow Units ............... CFS Process Models: Rainfall/Runoff ........ YES RDII ................... NO Snowmelt ............... NO Groundwater ............ NO Flow Routing ........... YES Ponding Allowed ........ NO Water Quality .......... NO Infiltration Method ...... HORTON Flow Routing Method ...... KINWAVE Starting Date ............ 01/01/2000 00:00:00 Ending Date .............. 01/06/2000 01:00:00 Antecedent Dry Days ...... 0.0 Report Time Step ......... 00:15:00 Wet Time Step ............ 00:05:00 Dry Time Step ............ 01:00:00 Routing Time Step ........ 30.00 sec ************************** Volume Depth Runoff Quantity Continuity acre-feet inches ************************** --------- ------- Total Precipitation ...... 18.077 3.669 Evaporation Loss ......... 0.000 0.000 Infiltration Loss ........ 4.376 0.888 Surface Runoff ........... 13.555 2.751 SWMM 5 Page 1 Final Storage ............ 0.237 0.048 Continuity Error (%) ..... -0.508 ************************** Volume Volume Flow Routing Continuity acre-feet 10^6 gal ************************** --------- --------- Dry Weather Inflow ....... 0.000 0.000 Wet Weather Inflow ....... 13.555 4.417 Groundwater Inflow ....... 0.000 0.000 RDII Inflow .............. 0.000 0.000 External Inflow .......... 0.000 0.000 External Outflow ......... 13.554 4.417 Flooding Loss ............ 0.000 0.000 Evaporation Loss ......... 0.000 0.000 Exfiltration Loss ........ 0.000 0.000 Initial Stored Volume .... 0.000 0.000 Final Stored Volume ...... 0.000 0.000 Continuity Error (%) ..... 0.012 ******************************** Highest Flow Instability Indexes ******************************** All links are stable. ************************* Routing Time Step Summary ************************* Minimum Time Step : 29.00 sec Average Time Step : 30.00 sec Maximum Time Step : 30.00 sec Percent in Steady State : 0.00 Average Iterations per Step : 1.00 Percent Not Converging : 0.00 *************************** Subcatchment Runoff Summary *************************** SWMM 5 Page 2 -------------------------------------------------------------------------------------------------------- Total Total Total Total Total Total Peak Runoff Precip Runon Evap Infil Runoff Runoff Runoff Coeff Subcatchment in in in in in 10^6 gal CFS -------------------------------------------------------------------------------------------------------- D2 3.67 0.00 0.00 1.03 2.61 2.77 193.03 0.712 D1 3.67 0.00 0.00 0.34 3.28 0.88 93.65 0.893 D3 3.67 0.00 0.00 0.87 2.78 0.76 61.90 0.757 ****************** Node Depth Summary ****************** --------------------------------------------------------------------------------- Average Maximum Maximum Time of Max Reported Depth Depth HGL Occurrence Max Depth Node Type Feet Feet Feet days hr:min Feet --------------------------------------------------------------------------------- outfall OUTFALL 0.00 0.00 96.00 0 00:00 0.00 ExistPondingArea STORAGE 1.69 5.18 102.18 0 03:07 5.18 Pond1 STORAGE 0.08 4.30 107.30 0 01:11 4.29 ******************* Node Inflow Summary ******************* ------------------------------------------------------------------------------------------------- Maximum Maximum Lateral Total Flow Lateral Total Time of Max Inflow Inflow Balance Inflow Inflow Occurrence Volume Volume Error Node Type CFS CFS days hr:min 10^6 gal 10^6 gal Percent ------------------------------------------------------------------------------------------------- outfall OUTFALL 0.00 5.00 0 02:07 0 4.42 0.000 ExistPondingArea STORAGE 286.68 295.80 0 00:40 3.65 4.42 0.010 Pond1 STORAGE 61.90 61.90 0 00:40 0.763 0.763 0.012 ********************* SWMM 5 Page 3 Node Flooding Summary ********************* No nodes were flooded. ********************** Storage Volume Summary ********************** -------------------------------------------------------------------------------------------------- Average Avg Evap Exfil Maximum Max Time of Max Maximum Volume Pcnt Pcnt Pcnt Volume Pcnt Occurrence Outflow Storage Unit 1000 ft3 Full Loss Loss 1000 ft3 Full days hr:min CFS -------------------------------------------------------------------------------------------------- ExistPondingArea 125.024 7 0 0 547.195 32 0 03:07 5.00 Pond1 0.650 0 0 0 46.169 18 0 01:11 12.00 *********************** Outfall Loading Summary *********************** ----------------------------------------------------------- Flow Avg Max Total Freq Flow Flow Volume Outfall Node Pcnt CFS CFS 10^6 gal ----------------------------------------------------------- outfall 70.83 1.91 5.00 4.416 ----------------------------------------------------------- System 70.83 1.91 5.00 4.416 ******************** Link Flow Summary ******************** ----------------------------------------------------------------------------- Maximum Time of Max Maximum Max/ Max/ |Flow| Occurrence |Veloc| Full Full Link Type CFS days hr:min ft/sec Flow Depth SWMM 5 Page 4 ----------------------------------------------------------------------------- Out_ExPnd DUMMY 5.00 0 02:07 P_1_Out DUMMY 12.00 0 00:52 ************************* Conduit Surcharge Summary ************************* No conduits were surcharged. Analysis begun on: Wed Jul 31 16:07:43 2019 Analysis ended on: Wed Jul 31 16:07:43 2019 Total elapsed time: < 1 sec SWMM 5 Page 5 Link P_1_Out Flow (CFS) Elapsed Time (hours) 0 20 40 60 80 100 120 140 Flow (CFS) 14.0 12.0 10.0 8.0 6.0 4.0 2.0 0.0 SWMM 5 Page 1 Node Pond1 Volume (ft3) Elapsed Time (hours) 0 20 40 60 80 100 120 140 Volume (ft3) 50000.0 45000.0 40000.0 35000.0 30000.0 25000.0 20000.0 15000.0 10000.0 5000.0 0.0 SWMM 5 Page 1 Link Out_ExPnd Flow (CFS) Elapsed Time (hours) 0 20 40 60 80 100 120 140 Flow (CFS) 6.0 5.0 4.0 3.0 2.0 1.0 0.0 SWMM 5 Page 1 Node ExistPondingArea Volume (ft3) Elapsed Time (hours) 0 20 40 60 80 100 120 140 Volume (ft3) 600000.0 500000.0 400000.0 300000.0 200000.0 100000.0 0.0 SWMM 5 Page 1 APPENDIX D Erosion Control Report Rennat Subdivision Preliminary Erosion Control Report A comprehensive Erosion and Sediment Control Plan (along with associated details) will be included with the final construction drawings. It should be noted, however, that any such Erosion and Sediment Control Plan serves only as a general guide to the Contractor. Staging and/or phasing of the BMPs depicted, and additional or different BMPs from those included may be necessary during construction, or as required by the authorities having jurisdiction. It shall be the responsibility of the Contractor to ensure erosion control measures are properly maintained and followed. The Erosion and Sediment Control Plan is intended to be a living document, constantly adapting to site conditions and needs. The Contractor shall update the location of BMPs as they are installed, removed or modified in conjunction with construction activities. It is imperative to appropriately reflect the current site conditions at all times. The Erosion and Sediment Control Plan shall address both temporary measures to be implemented during construction, as well as permanent erosion control protection. Best Management Practices from the Volume 3, Chapter 7 – Construction BMPs will be utilized. Measures may include, but are not limited to, silt fencing along the disturbed perimeter, gutter protection in the adjacent roadways and inlet protection at existing and proposed storm inlets. Vehicle tracking control pads, spill containment and clean-up procedures, designated concrete washout areas, dumpsters, and job site restrooms shall also be provided by the Contractor. Grading and Erosion Control Notes can be found on the Utility Plans. The Final Plans will contain a full-size Erosion Control sheet as well as a separate sheet dedicated to Erosion Control Details. In addition to this report and the referenced plan sheets, the Contractor shall be aware of, and adhere to, the applicable requirements outlined in the Development Agreement for the development. Also, the Site Contractor for this project will be required to secure a Stormwater Construction General Permit from the Colorado Department of Public Health and Environment (CDPHE), Water Quality Control Division – Stormwater Program, prior to any earth disturbance activities. Prior to securing said permit, the Site Contractor shall develop a comprehensive StormWater Management Plan (SWMP) pursuant to CDPHE requirements and guidelines. The SWMP will further describe and document the ongoing activities, inspections, and maintenance of construction BMPs. APPENDIX E USDA Soils Information United States Department of Agriculture A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Larimer County Natural Area, Colorado Resources Conservation Service July 24, 2019 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 5—Aquepts, loamy......................................................................................13 35—Fort Collins loam, 0 to 3 percent slopes.............................................. 14 36—Fort Collins loam, 3 to 5 percent slopes.............................................. 15 37—Fort Collins loam, 5 to 9 percent slopes.............................................. 17 55—Kim loam, 5 to 9 percent slopes.......................................................... 18 63—Longmont clay, 0 to 3 percent slopes.................................................. 19 73—Nunn clay loam, 0 to 1 percent slopes.................................................20 74—Nunn clay loam, 1 to 3 percent slopes.................................................22 79—Otero sandy loam, 5 to 9 percent slopes............................................. 23 103—Stoneham loam, 5 to 9 percent slopes.............................................. 25 References............................................................................................................27 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 4483400 4483500 4483600 4483700 4483800 4483900 4484000 4483400 4483500 4483600 4483700 4483800 4483900 4484000 495800 495900 496000 496100 496200 496300 496400 496500 496600 496700 495800 495900 496000 496100 496200 496300 496400 496500 496600 496700 40° 30' 25'' N 105° 3' 1'' W 40° 30' 25'' N 105° 2' 17'' W 40° 30' 3'' N 105° 3' 1'' W 40° 30' 3'' N 105° 2' 17'' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 200 400 800 1200 Feet 0 50 100 200 300 Meters Map Scale: 1:4,700 if printed on A landscape (11" x 8.5") 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 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 5 Aquepts, loamy 13.9 23.5% 35 Fort Collins loam, 0 to 3 percent slopes 5.1 8.6% 36 Fort Collins loam, 3 to 5 percent slopes 20.2 34.2% 37 Fort Collins loam, 5 to 9 percent slopes 0.1 0.2% 55 Kim loam, 5 to 9 percent slopes 3.3 5.5% 63 Longmont clay, 0 to 3 percent slopes 8.2 13.9% 73 Nunn clay loam, 0 to 1 percent slopes 0.1 0.2% 74 Nunn clay loam, 1 to 3 percent slopes 0.5 0.8% 79 Otero sandy loam, 5 to 9 percent slopes 7.6 12.9% 103 Stoneham loam, 5 to 9 percent slopes 0.1 0.2% Totals for Area of Interest 59.1 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They Custom Soil Resource Report 11 generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, 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 5—Aquepts, loamy Map Unit Setting National map unit symbol: jpws Elevation: 4,500 to 6,700 feet Mean annual precipitation: 12 to 18 inches Mean annual air temperature: 39 to 50 degrees F Frost-free period: 80 to 140 days Farmland classification: Not prime farmland Map Unit Composition Aquepts and similar soils: 80 percent Minor components: 20 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Aquepts Setting Landform: Draws, depressions, stream terraces Landform position (three-dimensional): Base slope, tread, dip Down-slope shape: Linear Across-slope shape: Linear Parent material: Loamy alluvium Typical profile H1 - 0 to 60 inches: variable Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Very poorly drained Runoff class: Negligible Capacity of the most limiting layer to transmit water (Ksat): Moderately high to very high (0.60 to 99.90 in/hr) Depth to water table: About 6 to 18 inches Frequency of flooding: Rare Frequency of ponding: None Interpretive groups Land capability classification (irrigated): 5w Land capability classification (nonirrigated): 3w Hydrologic Soil Group: A/D Hydric soil rating: Yes Minor Components Nunn Percent of map unit: 5 percent Hydric soil rating: No Kim Percent of map unit: 5 percent Hydric soil rating: No Custom Soil Resource Report 13 Stoneham Percent of map unit: 5 percent Hydric soil rating: No Fort collins Percent of map unit: 5 percent Hydric soil rating: No 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: 143 to 154 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 Down-slope shape: Linear Across-slope shape: Linear Parent material: Pleistocene or older alluvium derived from igneous, metamorphic and sedimentary rock 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 Natural 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 in profile: 12 percent Custom Soil Resource Report 14 Salinity, maximum in profile: Nonsaline (0.1 to 1.0 mmhos/cm) Sodium adsorption ratio, maximum in profile: 0.5 Available water storage in profile: High (about 9.1 inches) Interpretive groups Land capability classification (irrigated): 2e Land capability classification (nonirrigated): 4c Hydrologic Soil Group: C Ecological site: Loamy Plains (R067BY002CO) Hydric soil rating: No Minor Components Nunn Percent of map unit: 10 percent Landform: Terraces Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Ecological site: Loamy Plains (R067BY002CO) Hydric soil rating: No Vona Percent of map unit: 5 percent Landform: Interfluves Landform position (two-dimensional): Backslope, footslope Landform position (three-dimensional): Side slope, base slope Down-slope shape: Linear Across-slope shape: Linear Ecological site: Sandy Plains (R067BY024CO) Hydric soil rating: No 36—Fort Collins loam, 3 to 5 percent slopes Map Unit Setting National map unit symbol: jpw9 Elevation: 4,800 to 5,500 feet Mean annual precipitation: 13 to 15 inches Mean annual air temperature: 48 to 50 degrees F Frost-free period: 135 to 150 days Farmland classification: Prime farmland if irrigated Map Unit Composition Fort collins and similar soils: 90 percent Minor components: 10 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Fort Collins Setting Landform: Fans, terraces Custom Soil Resource Report 15 Landform position (three-dimensional): Base slope, riser Down-slope shape: Linear Across-slope shape: Linear Parent material: Alluvium Typical profile H1 - 0 to 9 inches: loam H2 - 9 to 20 inches: loam, clay loam H2 - 9 to 20 inches: loam, silt loam, fine sandy loam H3 - 20 to 60 inches: H3 - 20 to 60 inches: H3 - 20 to 60 inches: Properties and qualities Slope: 3 to 5 percent Depth to restrictive feature: More than 80 inches Natural 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 in profile: 15 percent Salinity, maximum in profile: Nonsaline to very slightly saline (0.0 to 2.0 mmhos/cm) Available water storage in profile: Very high (about 25.5 inches) Interpretive groups Land capability classification (irrigated): 3e Land capability classification (nonirrigated): 3e Hydrologic Soil Group: B Ecological site: Loamy Plains (R067XY002CO) Hydric soil rating: No Minor Components Ascalon Percent of map unit: 5 percent Hydric soil rating: No Kim Percent of map unit: 3 percent Hydric soil rating: No Stoneham Percent of map unit: 2 percent Hydric soil rating: No Custom Soil Resource Report 16 37—Fort Collins loam, 5 to 9 percent slopes Map Unit Setting National map unit symbol: jpwb Elevation: 4,800 to 5,500 feet Mean annual precipitation: 13 to 15 inches Mean annual air temperature: 48 to 50 degrees F Frost-free period: 135 to 150 days Farmland classification: Farmland of statewide importance 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: Fans, terraces Landform position (three-dimensional): Base slope, riser Down-slope shape: Linear Across-slope shape: Linear Parent material: Alluvium Typical profile H1 - 0 to 6 inches: loam H2 - 6 to 18 inches: loam, clay loam H2 - 6 to 18 inches: loam, silt loam, fine sandy loam H3 - 18 to 60 inches: H3 - 18 to 60 inches: H3 - 18 to 60 inches: Properties and qualities Slope: 5 to 9 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Runoff class: Medium 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 in profile: 15 percent Salinity, maximum in profile: Nonsaline to very slightly saline (0.0 to 2.0 mmhos/cm) Available water storage in profile: Very high (about 26.4 inches) Interpretive groups Land capability classification (irrigated): 4e Land capability classification (nonirrigated): 4e Custom Soil Resource Report 17 Hydrologic Soil Group: B Ecological site: Loamy Plains (R067XY002CO) Hydric soil rating: No Minor Components Larimer Percent of map unit: 8 percent Hydric soil rating: No Kim Percent of map unit: 4 percent Hydric soil rating: No Stoneham Percent of map unit: 3 percent Hydric soil rating: No 55—Kim loam, 5 to 9 percent slopes Map Unit Setting National map unit symbol: jpwz Elevation: 4,800 to 5,600 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: Farmland of local importance Map Unit Composition Kim and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Kim Setting Landform: Fans Landform position (three-dimensional): Base slope, side slope Down-slope shape: Linear Across-slope shape: Linear Parent material: Mixed alluvium Typical profile H1 - 0 to 7 inches: loam H2 - 7 to 60 inches: loam, clay loam, sandy clay loam H2 - 7 to 60 inches: H2 - 7 to 60 inches: Properties and qualities Slope: 5 to 9 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Custom Soil Resource Report 18 Runoff class: Medium 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 in profile: 15 percent Salinity, maximum in profile: Nonsaline to slightly saline (0.0 to 4.0 mmhos/cm) Available water storage in profile: Very high (about 26.5 inches) Interpretive groups Land capability classification (irrigated): 4e Land capability classification (nonirrigated): 6e Hydrologic Soil Group: B Ecological site: Loamy Plains (R067XY002CO) Hydric soil rating: No Minor Components Thedalund Percent of map unit: 10 percent Hydric soil rating: No Stoneham Percent of map unit: 5 percent Hydric soil rating: No 63—Longmont clay, 0 to 3 percent slopes Map Unit Setting National map unit symbol: jpx8 Elevation: 4,800 to 5,800 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 and reclaimed of excess salts and sodium Map Unit Composition Longmont and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Longmont Setting Landform: Flood plains, valleys Landform position (three-dimensional): Base slope, tread Down-slope shape: Linear Across-slope shape: Linear Parent material: Clayey alluvium derived from shale Custom Soil Resource Report 19 Typical profile H1 - 0 to 60 inches: clay Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Poorly drained Runoff class: High Capacity of the most limiting layer to transmit water (Ksat): Moderately low to moderately high (0.06 to 0.20 in/hr) Depth to water table: About 24 to 30 inches Frequency of flooding: Occasional Frequency of ponding: None Calcium carbonate, maximum in profile: 15 percent Gypsum, maximum in profile: 5 percent Salinity, maximum in profile: Slightly saline to strongly saline (4.0 to 16.0 mmhos/cm) Sodium adsorption ratio, maximum in profile: 20.0 Available water storage in profile: Moderate (about 8.4 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 6w Hydrologic Soil Group: D Ecological site: Salt Meadow (R067BY035CO) Hydric soil rating: No Minor Components Aquolls Percent of map unit: 5 percent Landform: Swales Hydric soil rating: Yes Dacono Percent of map unit: 5 percent Hydric soil rating: No Heldt Percent of map unit: 5 percent Hydric soil rating: No 73—Nunn clay loam, 0 to 1 percent slopes Map Unit Setting National map unit symbol: 2tlng Elevation: 4,100 to 5,700 feet Mean annual precipitation: 14 to 15 inches Mean annual air temperature: 48 to 52 degrees F Frost-free period: 135 to 152 days Farmland classification: Prime farmland if irrigated Custom Soil Resource Report 20 Map Unit Composition Nunn and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Nunn Setting Landform: Terraces Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Parent material: Pleistocene aged alluvium and/or eolian deposits Typical profile Ap - 0 to 6 inches: clay loam Bt1 - 6 to 10 inches: clay loam Bt2 - 10 to 26 inches: clay loam Btk - 26 to 31 inches: clay loam Bk1 - 31 to 47 inches: loam Bk2 - 47 to 80 inches: loam Properties and qualities Slope: 0 to 1 percent Depth to restrictive feature: More than 80 inches Natural 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 in profile: 7 percent Salinity, maximum in profile: Nonsaline (0.1 to 1.0 mmhos/cm) Sodium adsorption ratio, maximum in profile: 0.5 Available water storage in profile: High (about 9.1 inches) Interpretive groups Land capability classification (irrigated): 3e Land capability classification (nonirrigated): 4e Hydrologic Soil Group: C Ecological site: Clayey Plains (R067BY042CO) 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: Clayey Plains (R067BY042CO) Hydric soil rating: No Custom Soil Resource Report 21 Wages Percent of map unit: 5 percent Landform: Terraces Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Ecological site: Loamy Plains (R067BY002CO) Hydric soil rating: No 74—Nunn clay loam, 1 to 3 percent slopes Map Unit Setting National map unit symbol: 2tlpl Elevation: 3,900 to 5,840 feet Mean annual precipitation: 13 to 17 inches Mean annual air temperature: 50 to 54 degrees F Frost-free period: 135 to 160 days Farmland classification: Prime farmland if irrigated Map Unit Composition Nunn and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Nunn Setting Landform: Terraces Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Parent material: Pleistocene aged alluvium and/or eolian deposits Typical profile Ap - 0 to 9 inches: clay loam Bt - 9 to 13 inches: clay loam Btk - 13 to 25 inches: clay loam Bk1 - 25 to 38 inches: clay loam Bk2 - 38 to 80 inches: clay loam Properties and qualities Slope: 1 to 3 percent Depth to restrictive feature: More than 80 inches Natural 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 Custom Soil Resource Report 22 Calcium carbonate, maximum in profile: 7 percent Salinity, maximum in profile: Nonsaline to very slightly saline (0.1 to 2.0 mmhos/cm) Sodium adsorption ratio, maximum in profile: 0.5 Available water storage in profile: High (about 9.9 inches) Interpretive groups Land capability classification (irrigated): 2e Land capability classification (nonirrigated): 3e Hydrologic Soil Group: C Ecological site: Clayey Plains (R067BY042CO) 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: Clayey Plains (R067BY042CO) 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: Loamy Plains (R067BY002CO) Hydric soil rating: No 79—Otero sandy loam, 5 to 9 percent slopes Map Unit Setting National map unit symbol: jpxt Elevation: 4,800 to 5,600 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: Not prime farmland Map Unit Composition Otero and similar soils: 80 percent Minor components: 20 percent Estimates are based on observations, descriptions, and transects of the mapunit. Custom Soil Resource Report 23 Description of Otero Setting Landform: Fans Landform position (three-dimensional): Base slope, side slope Down-slope shape: Linear Across-slope shape: Linear Parent material: Alluvium and/or eolian deposits Typical profile H1 - 0 to 14 inches: sandy loam H2 - 14 to 60 inches: sandy loam, fine sandy loam, loamy very fine sand H2 - 14 to 60 inches: H2 - 14 to 60 inches: Properties and qualities Slope: 5 to 9 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Somewhat excessively drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat): High (2.00 to 6.00 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Calcium carbonate, maximum in profile: 5 percent Salinity, maximum in profile: Nonsaline to slightly saline (0.0 to 4.0 mmhos/cm) Available water storage in profile: Very high (about 15.4 inches) Interpretive groups Land capability classification (irrigated): 4e Land capability classification (nonirrigated): 6e Hydrologic Soil Group: A Ecological site: Sandy Plains (R067BY024CO) Hydric soil rating: No Minor Components Kim Percent of map unit: 9 percent Hydric soil rating: No Nelson Percent of map unit: 6 percent Hydric soil rating: No Tassel Percent of map unit: 5 percent Hydric soil rating: No Custom Soil Resource Report 24 103—Stoneham loam, 5 to 9 percent slopes Map Unit Setting National map unit symbol: jptw Elevation: 4,800 to 5,600 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: Farmland of local importance Map Unit Composition Stoneham and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Stoneham Setting Landform: 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 3 inches: loam H2 - 3 to 9 inches: clay loam, sandy clay loam, loam H2 - 3 to 9 inches: loam, clay loam, sandy clay loam H2 - 3 to 9 inches: H3 - 9 to 60 inches: H3 - 9 to 60 inches: H3 - 9 to 60 inches: Properties and qualities Slope: 5 to 9 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Runoff class: Medium 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 in profile: 15 percent Salinity, maximum in profile: Nonsaline to very slightly saline (0.0 to 2.0 mmhos/cm) Available water storage in profile: Very high (about 27.7 inches) Interpretive groups Land capability classification (irrigated): 6e Custom Soil Resource Report 25 Land capability classification (nonirrigated): 6e Hydrologic Soil Group: B Ecological site: Loamy Plains (R067XY002CO) Hydric soil rating: No Minor Components Kim Percent of map unit: 8 percent Hydric soil rating: No Larimer Percent of map unit: 5 percent Hydric soil rating: No Fort collins Percent of map unit: 2 percent Hydric soil rating: No Custom Soil Resource Report 26 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 27 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 28 MAP POCKET Drainage Exhibit 12" W 12" W X SS VAULT ELEC X X X X X IRR WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM WM UD UD UD E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G E E E G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G UD UD E E E E E E E E E E E E E E E E E G G G G G G G G G G G G G E E E E E E E E E E E E E E E E G G G G G G G G G G G G G G G G E E E G G UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD G G V AULT TELE T VAULT TELE W S O H Y D W TELE VAULT ELEC VAULT ELEC VAULT ELEC VAULT ELEC H Y D S S S ELEC E ELEC BRKR X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X SS SS SS SS SS SS LID VAULT F.O. W W W FO FO FO FO FO FO FO FO FO FO FO FO FO FO FO FO FO FO FO FO FO E E E E E E E E E T T T T T T T T T T T G G G G G G T T T W W W W W W W X X X X X X X X X X X X X X X X X X 4 1 2 3 6b 8 10 OS1 11a 4 11b 1 2 5 6b 7b 8 3 13 12 12 10 9 9 5 7b 11b OS1 6a 7a 7a 6a 11a MISTY MEADOW DR DANCING CATTAIL DR CROAKING TOAD DR FLYING MALLARD DR WINDY WILLOW DR MISTY MEADOW DR ZEPHYR RD FALLEN BRANCH DR AUTUMN BREEZE CT DITCH LATERAL UNION-PACIFIC RAILROAD EXISTING DETENTION POND DETENTION POND 1 RED WILLOW DRIVE DANCING CATTAIL DR 13 WATER QUALITY POND 1 WATER QUALITY POND 2 RAIN GARDEN 1 X X X X X X X Sheet RENNAT SUBDIVISION These drawings are instruments of service provided by Northern Engineering Services, Inc. and are not to be used for any type of construction unless signed and sealed by a Professional Engineer in the employ of Northern Engineering Services, Inc. NOT FOR CONSTRUCTION REVIEW SET E NGINEER ING N O R T H E RN FORT COLLINS: 301 North Howes Street, Suite 100, 80521 GREELEY: 820 8th Street, 80631 970.221.4158 northernengineering.com of 27 DR1 DRAINAGE EXHIBIT 27 CALL UTILITY NOTIFICATION CENTER OF COLORADO Know what'sbelow. Call before you dig. R NORTH MATCHLINE-THIS SHEET MATCHLINE-THIS SHEET LEGEND: PROPOSED CONTOUR PROPOSED STORM SEWER PROPOSED SWALE EXISTING CONTOUR PROPOSED CURB & GUTTER PROPERTY BOUNDARY PROPOSED INLET DESIGN POINT A FLOW ARROW DRAINAGE BASIN LABEL DRAINAGE BASIN BOUNDARY PROPOSED SWALE SECTION 1 B2 1.45 ac 1 FOR DRAINAGE REVIEW ONLY NOT FOR CONSTRUCTION DRAINAGE SUMMARY TABLE DESIGN POINT BASIN ID TOTAL AREA (acres) C2 C100 2-yr Tc (min) 100-yr Tc (min) Q2 (cfs) Q100 (cfs) 1 1 4.34 0.54 0.67 14.1 14.1 4.5 19.5 2 2 3.33 0.52 0.65 12.8 12.8 3.5 15.3 3 3 4.32 0.60 0.75 13.9 13.9 5.1 22.1 4 4 23.91 0.37 0.46 11.2 11.2 18.8 81.8 5 5 1.54 0.59 0.74 14.7 14.7 1.7 7.5 6a 6a 0.73 0.60 0.75 11.4 11.4 0.9 4.1 6b 6b 2.26 0.53 0.66 13.5 13.5 2.4 10.3 7a 7a 1.10 0.54 0.68 12.6 12.6 1.2 5.3 7b 7b 3.83 0.54 0.67 14.2 14.2 4.0 17.3 8 8 1.72 0.54 0.67 12.5 12.5 1.9 8.3 9 9 1.57 0.57 0.71 14.9 14.9 1.7 7.3 10 10 0.09 0.63 0.79 6.4 6.4 0.1 0.6 11a 11a 2.23 0.60 0.75 13.3 13.3 2.6 11.6 11b 11b 0.95 0.37 0.46 10.4 10.4 0.8 3.4 12 12 3.05 0.52 0.65 15.5 15.5 2.9 12.8 13 13 2.51 0.59 0.74 13.0 13.0 2.9 12.9 OS1 OS1 0.34 0.71 0.88 13.0 13.0 0.5 2.1 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 13, Sep 10, 2018 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 E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G E E E G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G G UD UD E E E E E E E E E E E E E E E E E G G G G G G G G G G G G G E E E E E E E E E E E E E E E E G G G G G G G G G G G G G G G G E E E G G UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD UD G G V AULT TELE T VAULT TELE W S O H Y D W TELE VAULT ELEC VAULT ELEC VAULT ELEC VAULT ELEC H Y D S S S ELEC E ELEC BRKR X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X SS SS SS SS SS SS LID VAULT F.O. W W W FO FO FO FO FO FO FO FO FO FO FO FO FO FO FO FO FO FO FO FO FO E E E E E E E E E T T T T T T T T T T T G G G G G G T T T W W W W W W W X X X X X X X X X X X X X X X X X X MISTY MEADOW DR DANCING CATTAIL DR CROAKING TOAD DR FLYING MALLARD DR WINDY WILLOW DR MISTY MEADOW DR ZEPHYR RD FALLEN BRANCH DR AUTUMN BREEZE CT DITCH LATERAL UNION-PACIFIC RAILROAD EXISTING DETENTION POND DETENTION POND 1 RED WILLOW DRIVE DANCING CATTAIL DR 1 2 6b 3 8 13 10 OS1 11a 4a 11b 12 9 5b 7b 6a 7a 5a 4b 4c 4e 4d RAIN GARDEN 1 GRASS LINED SWALE GRASS LINED SWALE WATER QUALITY POND 2 WATER QUALITY POND 1 X X X X X X X 4a Sheet RENNAT SUBDIVISION These drawings are instruments of service provided by Northern Engineering Services, Inc. and are not to be used for any type of construction unless signed and sealed by a Professional Engineer in the employ of Northern Engineering Services, Inc. NOT FOR CONSTRUCTION REVIEW SET E NGINEER ING N O R T H E RN FORT COLLINS: 301 North Howes Street, Suite 100, 80521 GREELEY: 820 8th Street, 80631 970.221.4158 northernengineering.com of 1 LID LID EXHIBIT 1 NORTH MATCHLINE-THIS SHEET MATCHLINE-THIS SHEET LEGEND: PROPOSED CONTOUR PROPOSED STORM SEWER PROPOSED SWALE EXISTING CONTOUR PROPOSED CURB & GUTTER PROPERTY BOUNDARY PROPOSED INLET DESIGN POINT A FLOW ARROW DRAINAGE BASIN LABEL DRAINAGE BASIN BOUNDARY PROPOSED SWALE SECTION 1 B2 1.45 ac 1 FOR DRAINAGE REVIEW ONLY NOT FOR CONSTRUCTION LID Summary per LID Structure LID ID Area Weighted % Impervious Subbasin ID Treatment Type Volume per UD-BMP (ft3) Impervious Area Sq. Ft. Acres (ft2) LID 1 266,074 6.11 61% 1, 4b Grass-Lined Swale 126,754 LID 2 813,147 18.67 71% 2, 3, 4c, 5a, 6a,7a, 8, 9, 13, OS1 Rain Garden 1 15,158 574,768 Total 1,079,220 24.78 701,522 LID Site Summary Total Site Area 2,532,032 ft2 Total Impervious Area 1,125,297 ft2 Total Impervious Area without LID Treatment 388,244 ft2 50% Requried Minium Area to be Treated 562,649 ft2 Total Treated Impervious Area 701,522 ft2 Percent Impervious Treated by LID 62.34% 55 0.87 1.48 3.03 22 1.53 2.61 5.32 56 0.86 1.47 2.99 23 1.49 2.55 5.20 57 0.85 1.45 2.96 24 1.46 2.49 5.09 58 0.84 1.43 2.92 25 1.43 2.44 4.98 59 0.83 1.42 2.89 26 1.4 2.39 4.87 60 0.82 1.4 2.86 27 1.37 2.34 4.78 65 0.78 1.32 2.71 28 1.34 2.29 4.69 70 0.73 1.25 2.59 29 1.32 2.25 4.60 75 0.70 1.19 2.48 30 1.30 2.21 4.52 80 0.66 1.14 2.38 31 1.27 2.16 4.42 85 0.64 1.09 2.29 32 1.24 2.12 4.33 90 0.61 1.05 2.21 33 1.22 2.08 4.24 95 0.58 1.01 2.13 34 1.19 2.04 4.16 100 0.56 0.97 2.06 35 1.17 2.00 4.08 105 0.54 0.94 2.00 36 1.15 1.96 4.01 110 0.52 0.91 1.94 37 1.16 1.93 3.93 115 0.51 0.88 1.88 38 1.11 1.89 3.87 120 0.49 0.86 1.84 July 30, 2019 Q  C f  C  i  A  Tt (min) 2-yr Tc (min) 10-yr Tc (min) 100-yr Tc (min) 1 1 No 0.25 0.25 0.31 110 2.00% 13.2 13.2 12.3 622 1.00% 2.00 5.2 0 0.00% N/A N/A 14.1 14.1 14.1 2 2 No 0.25 0.25 0.31 106 2.00% 13.0 13.0 12.0 393 1.00% 2.00 3.3 0 0.00% N/A N/A 12.8 12.8 12.8 3 3 No 0.25 0.25 0.31 124 2.00% 14.0 14.0 13.0 584 1.00% 2.00 4.9 0 0.00% N/A N/A 13.9 13.9 13.9 4 4 No 0.25 0.25 0.31 220 3.40% 15.7 15.7 14.5 0 0.00% N/A N/A 0 0.00% N/A N/A 11.2 11.2 11.2 5 5 No 0.25 0.25 0.31 48 2.00% 8.7 8.7 8.1 792 1.00% 2.00 6.6 0 0.00% N/A N/A 14.7 14.7 14.7 6a 6a No 0.25 0.25 0.31 52 2.00% 9.1 9.1 8.4 274 1.00% 2.00 2.3 0 0.00% N/A N/A 11.4 11.4 11.4 6b 6b No 0.25 0.25 0.31 50 2.00% 8.9 8.9 8.3 579 1.00% 2.00 4.8 0 0.00% N/A N/A 13.5 13.5 13.5 7a 7a No 0.25 0.25 0.31 105 2.00% 12.9 12.9 12.0 363 1.00% 2.00 3.0 0 0.00% N/A N/A 12.6 12.6 12.6 7b 7b No 0.25 0.25 0.31 98 2.00% 12.5 12.5 11.6 652 1.00% 2.00 5.4 0 0.00% N/A N/A 14.2 14.2 14.2 8 8 No 0.25 0.25 0.31 70 2.00% 10.6 10.6 9.8 372 1.00% 2.00 3.1 0 0.00% N/A N/A 12.5 12.5 12.5 9 9 No 0.25 0.25 0.31 48 2.00% 8.7 8.7 8.1 830 1.00% 2.00 6.9 0 0.00% N/A N/A 14.9 14.9 14.9 10 10 No 0.25 0.25 0.31 22 2.00% 5.9 5.9 5.5 58 1.00% 2.00 0.5 0 0.00% N/A N/A 6.4 6.4 6.4 11a 11a No 0.25 0.25 0.31 45 2.00% 8.5 8.5 7.8 575 1.00% 2.00 4.8 0 0.00% N/A N/A 13.3 13.3 13.3 11b 11b No 0.25 0.25 0.31 75 2.00% 10.9 10.9 10.1 0 0.00% N/A N/A 0 0.00% N/A N/A 10.4 10.4 10.4 12 12 No 0.25 0.25 0.31 124 2.00% 14.0 14.0 13.0 866 1.00% 2.00 7.2 0 0.00% N/A N/A 15.5 15.5 15.5 13 13 No 0.25 0.25 0.31 85 2.00% 11.6 11.6 10.8 462 1.00% 2.00 3.9 0 0.00% N/A N/A 13.0 13.0 13.0 OS1 OS1 No 0.25 0.25 0.31 85 2.00% 11.6 11.6 10.8 455 1.00% 2.00 3.8 0 0.00% N/A N/A 13.0 13.0 13.0 TIME OF CONCENTRATION COMPUTATIONS Gutter Flow Swale Flow Design Point Basin Overland Flow ATC July 30, 2019 Time of Concentration (Equation RO-4)   3 1 1 . 87 1 . 1 * S C Cf L Ti   8 74945 1.72 0.41 0.09 0.21 0.00 1.02 0.54 0.54 0.67 39% 9 68296 1.57 0.44 0.08 0.19 0.00 0.86 0.57 0.57 0.71 43% 10 3746 0.09 0.03 0.00 0.01 0.00 0.04 0.63 0.63 0.79 52% 11a 97116 2.23 0.74 0.11 0.27 0.00 1.11 0.60 0.60 0.75 48% 11b 41286 0.95 0.00 0.05 0.11 0.00 0.79 0.37 0.37 0.46 15% 12 132969 3.05 0.67 0.15 0.37 0.00 1.86 0.52 0.52 0.65 37% 13 109212 2.51 0.80 0.13 0.30 0.00 1.28 0.59 0.59 0.74 47% OS1 14994 0.34 0.17 0.02 0.04 0.00 0.12 0.71 0.71 0.88 63% COMPOSITE % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS Runoff Coefficients are taken from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards, Table3.2-2. % Impervious taken from UDFCD USDCM, Volume I. NOTE: Impervious areas have been estimated for preliminary design and planning purposes and are subject to change at Final Design. 10-year Cf = 1.00 July 30, 2019