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Home My WebLink AboutSNOW RIDGE APARTMENTS - PDP230014 - SUBMITTAL DOCUMENTS - ROUND 2 - DRAINAGE REPORT PRELIMINARY DRAINAGE REPORT SNOW RIDGE APARTMENTS FORT COLLINS, COLORADO NOVEMBER 15, 2023 NORTHERNENGINEERING.COM 970.221.4158 FORT COLLINS GREELEY This Drainage Report is consciously provided as a PDF. Please consider the environment before printing this document in its entirety. When a hard copy is necessary, we recommend double-sided printing. NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: SNOW RIDGE APARTMENTS FORT COLLINS | GREELEY COVER LETTER November 15, 2023 City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, CO 80521 RE: PRELIMINARY DRAINAGE REPORT FOR SNOW RIDGE APARTMENTS Dear Staff: Northern Engineering is pleased to submit this Preliminary Drainage Report for your review. This report accompanies the Preliminary submittal for the proposed Snow Ridge Apartments. This report has been prepared in accordance with the Fort Collins Stormwater Criteria Manual (FCSCM) and serves to document the stormwater impacts associated with the project. We understand that review by the City of Fort Collins is to assure general compliance with standardized criteria contained in the FCSCM. If you should have any questions as you review this report, please feel free to contact us. Sincerely, NORTHERN ENGINEERING SERVICES, INC. AMANDA POINCELOT JACOB O’BANION Project Manager Project Engineer Compliance Statement I hereby attest that this report for the preliminary drainage design for the Gateway Apartments was prepared by me or under my direct supervision, in accordance with the provisions of the Fort Collins Stormwater Criteria Manual. I understand that the City of Fort Collins does not and will not assume liability for drainage facilities designed by others. NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: SNOW RIDGE APARTMENTS FORT COLLINS | GREELEY TABLE OF CONTENTS TABLE OF CONTENTS GENERAL LOCATION AND DESCRIPTION .......................................................... 1 DRAIN BASINS AND SUB-BASINS ..................................................................... 3 DRAINAGE DESIGN CRITERIA .......................................................................... 4 DRAINAGE FACILITY DESIGN ........................................................................... 6 CONCLUSIONS .............................................................................................. 7 REFERENCES ................................................................................................ 8 TABLES AND FIGURES FIGURE 1 – AERIAL PHOTOGRAPH ...................................................................................1 FIGURE 2 – FEMA FIRMETTE .............................................................................................3 FIGURE 3 – EXISTING CITY FLOODPLAINS ........................................................................3 TABLE 1 - DETENTION SUMMARY .....................................................................................7 APPENDICES APPENDIX A – HYDROLOGIC COMPUTATIONS APPENDIX B – HYDRAULIC CALCULATIONS APPENDIX C –WATER QUALITY/LID COMPUTATIONS APPENDIX D – EROSION CONTROL REPORT APPENDIX E – USDA SOILS REPORT MAP POCKET DR1 – DRAINAGE EXHIBIT NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: SNOW RIDGE APARTMENTS FORT COLLINS | GREELEY 1 | 11 GENERAL LOCATION AND DESCRIPTION A. LOCATION Vicinity Map The Snow Ridge Apartments project site is a tract of land located in the southeast quarter of Section 15, Township 7 North, Range 69 West of the 6th Principal Meridian, City of Fort Collins, County of Larimer, State of Colorado. The project site (refer to Figure 1) is bordered to the north by an existing single-family residential area; to the south by Prospect Road; to the east by Shields Street; and to the west by an existing single-family residential area. B. DESCRIPTION OF PROPERTY The Snow Ridge Apartments is a ± 0.67-acre tract. The site is currently zoned as Neighborhood Conservation, Buffer District (N-C-B) with one existing residential structure on site. The subject property is not located within a FEMA floodplain or within a City of Fort Collins regulatory floodplain. Figure 1 – Aerial Photograph NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: SNOW RIDGE APARTMENTS FORT COLLINS | GREELEY 2 | 11 The existing groundcover consists of grass with tree cover, a residential structure, and an asphalt driveway. The existing on-site runoff of the western two thirds of the property generally drains from the east-to-southwest where it sheet flows to the adjacent properties to the south and west. The existing on-site runoff of the eastern third of the property generally drains from the west-to-east across moderately flat grades (e.g., <6.00%) onto Shields Street. From there, the drainage continues to Prospect Road, and is received by the New Mercer Canal. According to the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Soil Survey, the site consists primarily of Altvan-Satana loams which fall into Hydrologic Soil Group B. The proposed development is an 8-unit complex. Consisting of a conversion of the existing residential structure to a 2-unit complex and the addition of (3) 2-unit interconnected structures. Other proposed improvements include a new drive aisle consisting of concrete and permeable pavers, new sidewalks and new landscaping, a mailroom with bike storage, outdoor bike parking, trash enclosure, and a patio common area. The proposed land use is Multi-Family Residential. This is a permitted use in the existing Neighborhood Conservation Buffer (NCB) zoning between CSU/Downtown and the residential neighborhoods to the west. NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: SNOW RIDGE APARTMENTS FORT COLLINS | GREELEY 3 | 11 C. FLOODPLAIN The subject property is not located within a FEMA floodplain or within a City regulatory floodplain. Figure 2 – FEMA FIRMette Figure 3 – Existing City Floodplains NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: SNOW RIDGE APARTMENTS FORT COLLINS | GREELEY 4 | 11 DRAIN BASINS AND SUB-BASINS A. MAJOR BASIN DESCRIPTION a) The Snow Ridge Apartments project is located within the Canal Importation Basin. The Canal Importation Basin encompasses almost five square miles (3,200 acres) of west-central Fort Collins. Three irrigation canals pass through the basin flowing generally from north to south. The runoff from the Snow Ridge Apartments is received by the New Mercer Canal which generally flows west to east. B. SUB-BASIN DESCRIPTION The project site is broken up into five sub-basins. Three on-site basins and two off-site basins. The central and western on-site basins are connected via a subdrain that receives infiltration from the pavers located in the drive isle within both basins. The eastern onsite basin flows to the proposed detention pond adjacent to Shields Street. The project site has one outfall location which is the existing flowline of Shields Street. The project site does not receive notable runoff from contiguous off-site properties. DRAINAGE DESIGN CRITERIA A. STORMWATER MANAGEMENT STRATEGY The overall stormwater management strategy employed with Snow Ridge Apartments 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. Snow Ridge Apartments aims to reduce runoff peaks, volumes and pollutant loads from frequently occurring storm events (i.e., water quality (i.e., 80th percentile) and 2-year storm events) by implementing Low Impact Development (LID) strategies. Wherever practical, runoff will be routed across landscaped areas or through Permeable Interlocking Concrete Pavers (PICP). These LID practices reduce the overall amount of impervious area, while at the same time Minimizing Directly Connected Impervious Areas (MDCIA). The combined LID/MDCIA techniques will be implemented, where practical, throughout the development, thereby slowing runoff and increasing opportunities for infiltration. Step 2 – Implement BMPs that Provide a Water Quality Capture Volume (WQCV) with Slow Release. The efforts taken in Step 1 will help to minimize excess runoff from frequently occurring storm events; however, urban development of this intensity will still have stormwater runoff leaving the site. The primary water quality treatment will occur via Permeable Interlocking Concrete Pavers (PICP) to a subdrain beneath the parking and drive isle from the northwest part of the site that flows to the detention pond in the east. In addition to LID treatment, traditional water quality treatment will be provided within the lower stages of the detention pond. Step 3 – Stabilize Drainageways. The Snow Ridge Apartments project aims to protect the existing New Mercer Canal by limiting any increases beyond historical flow rates within the ditch. By utilizing a combination of LID, traditional water quality treatment, and a detention pond. As such, the peak discharge from the Snow Ridge Apartments project will not be compounded with peak flow in the ditch. Furthermore, this project will pay a one-time stormwater development fee, as well as ongoing monthly utility fees, both of which help achieve citywide drainage stability. Step 4 – Implement Site Specific and Other Source Control BMPs. This step typically applies to industrial and commercial developments. This does not apply to this site. NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: SNOW RIDGE APARTMENTS FORT COLLINS | GREELEY 5 | 11 B. DEVELOPMENT CRITERIA REFERENCE AND CONSTRAINTS The subject property is part of the Canal Importation Basin Master Drainage Plan. The site plan is constrained on the north, south, and west by residential properties, and on the east side by Shields Street. C. HYDROLOGICAL CRITERIA 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 Snow Ridge Apartments development. Data contained in Table 3.4-1 has been utilized for Rational Method runoff calculations. The Rational Method has been employed to compute stormwater runoff utilizing coefficients contained in Tables 4.1-2 and 4.1-3 of the FCSCM. Two separate design storms have been utilized to address distinct drainage scenarios. The first event analyzed is the “Minor,” or “Initial” Storm, which has a 2-year recurrence interval. The second event considered is the “Major Storm,” which has a 100-year recurrence interval. D. HYDRAULIC CRITERIA The drainage facilities proposed with the Snow Ridge Apartments development project are designed in accordance with criteria outlined in the Mile High Flood District’s “Urban Storm Drainage Criteria Manual” (UDFCD) and the Fort Collins Stormwater Criteria Manual (FCSCM). As stated in Section I.B.3, above, the subject property is not located within a FEMA floodplain or within a City of Fort Collins regulatory floodplain. E. CONFORMANCE WITH WATER QUALITY TREATMENT CRITERIA City Code requires that 100% of runoff from a project site receive some sort of water quality treatment. This project proposes to provide water quality treatment using Permeable Interlocking Concrete Pavers (PICP) and traditional water within the lower stages of the detention pond. Through these methods 100% of the on-site area will be treated for water quality. F. CONFORMANCE WITH LOW IMPACT DEVELOPMENT (LID) The project site will conform with the requirement to treat a minimum of 50% of the proposed impervious surfaces using LID treatment from PICP pavers. Please see Appendix C for LID design information, table, and exhibit(s). As shown in the LID table provided in the appendix, 60.94% of the proposed site impervious area will receive LID treatment from PICP pavers, which exceeds the minimum required. NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: SNOW RIDGE APARTMENTS FORT COLLINS | GREELEY 6 | 11 G. SIZING OF LID SYSTEMS Permeable Pavers Systems The type of Permeable Pavement sections chosen for this project are Permeable Interlocking Concrete Pavers. The effective imperviousness of area tributary to permeable pavement, the tributary watershed area and the area of the permeable pavement system were used to determine the required storage volumes for each area of the PICPs. The minimum depth of reservoir, the slope of the subgrade, the porosity of the subgrade, the slope of the subgrade interface, and the length between lateral flow barriers were used to determine the volume provided based on the depth of base course. DRAINAGE FACILITY DESIGN A. GENERAL CONCEPT The main objective of the Snow Ridge Apartments project drainage design is to maintain existing drainage patterns, while not adversely impacting adjacent properties. A list of tables and figures used within this report can be found in the Table of Contents at the front of the document. The tables and figures are located within the sections to which the content best applies. Drainage for the project site has been analyzed using five (5) drainage sub-basins. On-site is designated as sub-basins A1, A2, and A3. Offsite basins designated as OS1 and OS2. The drainage patterns anticipated for the basins are further described below. Sub-Basin A1 Sub-basin A1 is comprised of a section of the drive Isle, portions of the multi-family development, vegetated area, and the detention pond. Drainage is routed to the pond via curb/gutters, swales and a concrete drain pan. Sub-Basin A2 Sub-basin A2 is comprised of portions of the multifamily development and the drive isle. Drainage is routed to Paver 1 where it will be treated for LID prior to infiltration and release via subdrain to the pond. Sub-Basin A3 Sub-basin A3 is comprised of portions of the multifamily development including the parking area and drive isle, and vegetated area. Drainage is routed to Paver 2 where it will be treated for LID prior to infiltration and release via subdrain to the pond. A low spot within A3 gathers the overflow from the runoff of Paver 2 and a small portion of the multifamily development and directs it to the pond via storm pipe and concrete drain pan. Sub-Basin OS1 Sub-basin OS1 is comprised of the proposed right of way and utility easement, which includes vegetated area, the pond outlet, a portion of sidewalk, and the entrance. Drainage is routed to the flowline in Shields St. Sub-Basin OS2 Sub-basin OS2 is comprised of vegetated area. This area follows the historic drainage pattern and goes southwest. A full-size copy of the Drainage Exhibit can be found in the Map Pocket at the end of this report. NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: SNOW RIDGE APARTMENTS FORT COLLINS | GREELEY 7 | 11 B. SPECIFIC DETAILS Snow Ridge Apartments is bounded by residential lots to the north, south and west and adjacent to Shields Street on the east. The site will be discharging to Shields Street. In order to reduce runoff peaks, volumes and pollutant loads from urbanizing areas, LID strategies and a detention pond are proposed. Snow Ridge Apartments proposes providing 100-year detention and utilizing extended detention for water quality. Permeable Interlocking Concrete Pavers are proposed to treat on-site runoff and conform with LID practices established in the UDFCD and Fort Collins Stormwater Criteria Manual. Detention Pond Calculations: a) Detention Pond Calculations were done via FAA Modified method as described in Chapter 6, Section 2.3 in the City of Fort Collins Stormwater Criteria Manual. Pond ID Tributary Area (ac) Weighted Percent Imperviousness (%) Extended Detention WQCV (ac- ft) LID WQCV (ac-ft) 100-Yr Detention Vol. (ac- ft) Total Pond Volume (ac-ft) 100-Yr Detention WSEL (ft) Final Release Rate (cfs) Pond 1 0.22 52 0.004 N/A 0.050 0.054 5037.41 0.60 Paver 1 0.15 70 N/A 0.003 N/A N/A N/A N/A Paver 2 0.14 57 N/A 0.002 N/A N/A N/A N/A Table 1 - Detention Summary CONCLUSIONS A. COMPLIANCE WITH STANDARDS The detention design proposed with the Snow Ridge Apartments project does comply with the City of Fort Collins’ Stormwater Criteria Manual. The drainage design proposed with the Snow Ridge Apartments complies with the City of Fort Collins Canal Importation Master Drainage Plan. The drainage plan and stormwater management measures proposed with the Snow Ridge Apartments project are compliant with all applicable State and Federal regulations governing stormwater discharge. B. DRAINAGE CONCEPT The drainage design proposed with this project will effectively limit potential damage associated with its stormwater runoff. The proposed Snow Ridge Apartments development will not impact the Master Drainage Plan recommendations for the Canal Importation Basin. NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: SNOW RIDGE APARTMENTS FORT COLLINS | GREELEY 8 | 11 REFERENCES 1. City of Fort Collins Landscape Design Guidelines for Stormwater and Detention Facilities, November 5, 2009, BHA Design, Inc. with City of Fort Collins Utility Services. 2. Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, as adopted by Ordinance No. 159, 2018, and referenced in Section 26-500 of the City of Fort Collins Municipal Code. 3. Soils Resource Report for Larimer County Area, Colorado, Natural Resources Conservation Service, United States Department of Agriculture. 4. Urban Storm Drainage Criteria Manual, Volumes 1-3, Urban Drainage and Flood Control District, Wright-McLaughlin Engineers, Denver, Colorado, Revised April 2008. 5. Canal Importation Basin Master Drainage Plan Hydraulic Evaluation and Mapping Update, City of Fort Collins, Colorado, Anderson Consulting Engineers, Inc., Fort Collins, Colorado, July 22, 2014. NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: SNOW RIDGE APARTMENTS FORT COLLINS | GREELEY APPENDIX APPENDIX A HYDROLOGIC COMPUTATIONS Runoff Coefficient1 Percent Impervious1 Project: Location: 0.95 100%Calc. By: 0.95 90%Date: 0.15 2% Basin ID Basin Area (sq.ft.) Basin Area (acres) Asphalt, Concrete (acres)Rooftop (acres) Lawns, Sandy Soil, Avg Slope 2-7% (acres) Percent Impervious C2*Cf Cf = 1.00 C5*Cf Cf = 1.00 C10*Cf Cf = 1.00 C100*Cf Cf = 1.25 HA1 10,496 0.24 0.08 0.03 0.14 0.00 43% 0.50 0.50 0.50 0.62 HA2 18,660 0.43 0.02 0.02 0.39 0.00 11% 0.23 0.23 0.23 0.28 Total 29,156 0.67 0.10 0.05 0.52 0.00 23% 0.32 0.32 0.32 0.41 2) Composite Runoff Coefficient adjusted per Table 3.2-3 of the Fort Collins Stormwater Manual (FCSM).USDA SOIL TYPE: B 1) Runoff coefficients per Tables 3.2-1 & 3.2 of the FCSM. Percent impervious per Tables 4.1-2 & 4.1-3 of the FCSM. HISTORIC RUNOFF COEFFICIENT CALCULATIONS Asphalt, Concrete Rooftop Lawns, Sandy Soil, Avg Slope 2-7% Streets, Parking Lots, Roofs, Alleys, and Drives: Character of Surface:Snow Ridge Apartments Fort Collins J. Obanion Nov. 9, 2023 Notes: 1) A1 drains Southeast to Shields Street 2) A2 drainas Southwest to adjacent property line Page 1 of 4 Snow Ridge Apartments Nov. 9, 2023 Where: C2*Cf C100*Cf Length (ft) Elev Up Elev Down Slope (%) Ti 2-Yr (min) Ti 100-Yr (min) Length (ft) Elev Up Elev Down Slope (%)Surface n Flow Area3 (sq.ft.) WP3 (ft)R (ft)V (ft/s) Tt (min) Max. Tc (min) Comp. Tc 2-Yr (min) Tc 2-Yr (min) Comp. Tc 100- Yr (min) Tc 100-Yr (min) HA1 ha1 0.50 0.62 37 38.77 37.95 2.21%5.26 4.17 121 37.95 35.55 1.99%Swale (8:1)0.035 8.00 16.12 0.50 3.77 0.53 10.88 5.80 5.80 4.71 5.00 HA2 ha2 0.23 0.28 55 38.69 37.46 2.23%9.28 8.68 126 37.46 36.25 0.96% Swale (8:1)0.035 8.00 16.12 0.50 2.61 0.80 11.01 10.09 10.09 9.49 9.49 total Total 0.36 0.45 37 38.77 37.95 2.21%6.44 5.65 121 37.95 35.55 1.99% Swale (8:1)0.035 8.00 16.12 0.50 3.77 0.53 10.88 6.98 6.98 6.18 6.18 Design Point Basin ID Overland Flow Channelized Flow Time of Concentration HISTORIC TIME OF CONCENTRATION COMPUTATIONS Location: Maximum Tc:Overland Flow, Time of Concentration: Channelized Flow, Velocity: Channelized Flow, Time of Concentration: Snow Ridge Apartments Fort Collins J. Obanion Nov. 9, 2023 Project: Calculations By: Date: Notes S = Longitudinal Slope, feet/feet R = Hydraulic Radius (feet) n = Roughness Coefficient V = Velocity (ft/sec) WP = Wetted Perimeter (ft) (Equation 3.3-2 per Fort Collins Stormwater =1.87 1.1 − ∗ =1.49 ∗ / ∗ (Equation 5-4 per Fort Collins Stormwater = 180 + 10 (Equation 3.3-5 per Fort Collins Stormwater Manual) = ∗ 60 (Equation 5-5 per Fort Collins 1) Add 4900 to all elevations. 2) Per Fort Collins Stormwater Manual, minimum Tc = 5 min. 3) Assume a water depth of 6" and a typical curb and gutter per Larimer County Urban Street Standard Detail 701 for curb and gutter channelized flow. Assume a water depth of 1', fixed side slopes, and a triangular swale section for grass channelized flow. Assume a water depth Page 2 of 4 Tc2 Tc10 Tc100 C2 C10 C100 I2 I10 I100 Q2 Q10 Q100 HA1 ha1 0.24 5.8 5.8 5.0 0.5 0.5 0.6 2.8 4.7 10.0 0.3 0.6 1.5 HA2 ha2 0.43 10.1 10.1 9.5 0.2 0.2 0.3 2.2 3.8 8.0 0.2 0.4 1.0 total Total 0.67 7.0 7.0 6.2 0.3 0.3 0.4 2.6 4.4 9.3 0.6 1.0 2.5 Rational Equation: Q = CiA (Equation 6-1 per MHFD) Area (acres) Runoff CTc (Min) HISTORIC DIRECT RUNOFF COMPUTATIONS Intensity (in/hr)Flow (cfs) Snow Ridge Apartments J. Obanion Nov. 9, 2023Date: Fort Collins Project: Location: Calc. By: Design Point Basin Intensity, I, from Fig. 3.4.1 Fort Collins Stormwater Manual. Page 3 of 4 Runoff Coefficient1 Percent Impervious1 Project: Location: 0.95 100%Calc. By: 0.95 90%Date: 0.50 40% 0.80 80% 0.15 2% Basin ID Basin Area (sq.ft.) Basin Area (acres) Asphalt, Concrete (acres)Rooftop (acres) Pavers (acres) Lawns, Sandy Soil, Avg Slope 2-7% (acres) Recycled Asphalt (acres) Lawns, Sandy Soil, Avg Slope 2-7% (acres) Percent Impervious C2*Cf Cf = 1.00 C5*Cf Cf = 1.00 C10*Cf Cf = 1.00 C100*Cf Cf = 1.25 A1 9,795 0.22 0.07 0.05 0.00 0.00 0.00 0.10 52% 0.58 0.58 0.58 0.72 A2 6,552 0.15 0.05 0.04 0.05 0.00 0.00 0.01 70% 0.74 0.74 0.74 0.93 A3 5,895 0.14 0.06 0.01 0.03 0.00 0.00 0.04 57% 0.61 0.61 0.61 0.77 Total 22,242 0.51 0.18 0.10 0.08 0.00 0.00 0.16 59% 0.63 0.63 0.63 0.79 OS1 2,780 0.06 0.02 0.00 0.00 0.00 0.00 0.04 39% 0.45 0.45 0.45 0.56 OS2 4,134 0.09 0.00 0.00 0.00 0.00 0.00 0.09 5% 0.18 0.18 0.18 0.22 Total 6,914 0.16 0.03 0.00 0.00 0.00 0.00 0.13 19% 0.29 0.29 0.29 0.36 Offsite Basins Lawns and Landscaping: 2) Composite Runoff Coefficient adjusted per Table 3.2-3 of the Fort Collins Stormwater Manual (FCSM). Lawns, Sandy Soil, Avg Slope 2-7% USDA SOIL TYPE: B Recycled Asphalt Composite Runoff Coefficient2 1) Runoff coefficients per Tables 3.2-1 & 3.2 of the FCSM. Percent impervious per Tables 4.1-2 & 4.1-3 of the FCSM. DEVELOPED RUNOFF COEFFICIENT CALCULATIONS Asphalt, Concrete Rooftop Pavers Streets, Parking Lots, Roofs, Alleys, and Drives: Character of Surface:Snow Ridge Apartments Fort Collins J. Obanion November 9, 2023 Page 1 of 3 Where: C2*Cf C100*Cf Length (ft) Elev Up Elev Down Slope (%) Ti 2-Yr (min) Ti 100-Yr (min) Length (ft) Elev Up Elev Down Slope (%)Surface n Flow Area3 (sq.ft.) WP3 (ft)R (ft)V (ft/s) Tt (min) Max. Tc (min) Comp. Tc 2-Yr (min) Tc 2-Yr (min) Comp. Tc 100- Yr (min) Tc 100-Yr (min) a1 A1 0.58 0.72 35 38.77 38.00 2.20%4.45 3.22 152 38.00 36.00 1.32%Swale (6:1)0.035 6.00 12.17 0.49 3.05 0.83 11.04 5.28 5.28 4.05 5.00 a2 A2 0.74 0.93 35 39.37 37.61 5.03%2.32 1.12 120 37.61 36.73 0.73% Swale (8:1)0.035 8.00 16.12 0.50 2.29 0.88 10.86 3.19 5.00 2.00 5.00 a3 A3 0.61 0.77 35 37.86 37.50 1.03%5.34 3.66 54 37.50 37.21 0.54% Swale (8:1)0.035 8.00 16.12 0.50 1.96 0.46 10.49 5.80 5.80 4.12 5.00 total Total 0.63 0.79 35 37.86 37.50 1.03%5.10 3.36 120 37.61 36.73 0.73% Swale (8:1)0.035 8.00 16.12 0.50 2.29 0.88 10.86 5.97 5.97 4.23 5.00 os1 OS1 0.45 0.56 35 37.00 36.00 2.86%5.05 4.17 0 0.00 0.00 N/A Swale (8:1)0.000 8.00 16.12 N/A N/A 0.00 10.19 5.05 5.05 4.17 5.00 os2 OS2 0.18 0.22 35 38.00 36.00 5.71%5.72 5.45 0 0.00 0.00 N/A Swale (8:1)0.000 8.00 16.12 N/A N/A 0.00 10.19 5.72 5.72 5.45 5.45 total Total 0.29 0.36 35 37.00 36.00 2.86%5.05 4.17 0 0.00 0.00 N/A Swale (8:1)0.000 8.00 16.12 N/A N/A 0.00 10.19 5.05 5.05 4.17 5.00 Offsite Basins Design Point Basin ID Overland Flow Channelized Flow Time of Concentration DEVELOPED TIME OF CONCENTRATION COMPUTATIONS Location: Maximum Tc:Overland Flow, Time of Concentration: Channelized Flow, Velocity: Channelized Flow, Time of Concentration: Snow Ridge Apartments Fort Collins J. Obanion November 9, 2023 Project: Calculations By: Date: Notes S = Longitudinal Slope, feet/feet R = Hydraulic Radius (feet) n = Roughness Coefficient V = Velocity (ft/sec) WP = Wetted Perimeter (ft) (Equation 3.3-2 per Fort Collins Stormwater =1.87 1.1 − ∗ =1.49 ∗ / ∗ (Equation 5-4 per Fort Collins Stormwater = 180 + 10 (Equation 3.3-5 per Fort Collins Stormwater Manual) = ∗ 60 (Equation 5-5 per Fort Collins 1) Add 4900 to all elevations. 2) Per Fort Collins Stormwater Manual, minimum Tc = 5 min. 3) Assume a water depth of 6" and a typical curb and gutter per Larimer County Urban Street Standard Detail 701 for curb and gutter channelized flow. Assume a water depth of 1', fixed side slopes, and a triangular swale section for grass channelized flow. Assume a water depth Page 2 of 3 Tc2 Tc10 Tc100 C2 C100 I2 I10 I100 Q2 Q100 a1 A1 0.22 5.3 5.3 5.0 0.6 0.7 2.9 4.9 10.0 0.4 1.6 a2 A2 0.15 5.0 5.0 5.0 0.7 0.9 2.9 4.9 10.0 0.3 1.4 a3 A3 0.14 5.8 5.8 5.0 0.6 0.8 2.8 4.7 10.0 0.2 1.0 total Total 0.51 6.0 6.0 5.0 0.6 0.8 2.8 4.7 10.0 0.9 4.0 os1 OS1 0.06 5.1 5.1 5.0 0.5 0.6 2.9 4.9 10.0 0.1 0.4 os2 OS2 0.09 5.7 5.7 5.4 0.2 0.2 2.8 4.7 10.0 0.0 0.2 total Total 0.16 5.1 5.1 5.0 0.3 0.4 2.9 4.9 10.0 0.1 0.6 DEVELOPED DIRECT RUNOFF COMPUTATIONS Intensity (in/hr)Flow (cfs) Snow Ridge Apartments J. Obanion November 9, 2023 Design Point Basin Intensity, I, from Fig. 3.4.1 Fort Collins Stormwater Manual. Rational Equation: Q = CiA (Equation 6-1 per MHFD) Area (acres) Runoff CTc (Min) Offsite Basins Date: Fort Collins Project: Location: Calc. By: Page 3 of 3 Pond No : A1 100-yr 0.79 5.00 min 2198 ft3 0.51 acres 0.050 ac-ft Max Release Rate =0.60 cfs Time (min) Ft Collins 100-yr Intensity (in/hr) Inflow Volume (ft3) Outflow Adjustment Factor Qav (cfs) Outflow Volume (ft3) Storage Volume (ft3) 5 9.950 1203 1.00 0.60 180 1023 10 7.720 1866 1.00 0.60 360 1506 15 6.520 2364 1.00 0.60 540 1824 20 5.600 2707 1.00 0.60 720 1987 25 4.980 3010 1.00 0.60 900 2110 30 4.520 3278 1.00 0.60 1080 2198 35 4.080 3452 1.00 0.60 1260 2192 40 3.740 3616 1.00 0.60 1440 2176 45 3.460 3764 1.00 0.60 1620 2144 50 3.230 3904 1.00 0.60 1800 2104 55 3.030 4029 1.00 0.60 1980 2049 60 2.860 4148 1.00 0.60 2160 1988 65 2.720 4274 1.00 0.60 2340 1934 70 2.590 4383 1.00 0.60 2520 1863 75 2.480 4496 1.00 0.60 2700 1796 80 2.380 4603 1.00 0.60 2880 1723 85 2.290 4705 1.00 0.60 3060 1645 90 2.210 4808 1.00 0.60 3240 1568 95 2.130 4892 1.00 0.60 3420 1472 100 2.060 4980 1.00 0.60 3600 1380 105 2.000 5077 1.00 0.60 3780 1297 110 1.940 5159 1.00 0.60 3960 1199 115 1.890 5254 1.00 0.60 4140 1114 120 1.840 5338 1.00 0.60 4320 1018 *Note: Using the method described in FCSCM Chapter 6 Section 2.3 A = Tc = Project Location : Design Point C = Design Storm DETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDF Input Variables Results Required Detention Volume Fort Collins, Colorado 2047-001 Snow Ridge Apartments Project Number : Project Name : Pond 1 Page 1 of 1 2047-001_FAAModified Pond Stage-Storage Curve Pond: 1 Project: 2047-001 Snow Ridge Apartments By: Jacob Obanion Date: 11/09/2023 Stage (FT) Contour Area (SF) Volume (CU.FT.) Volume (AC-FT) 5,036.00 343.94 0.000 0.000 5,036.20 869.80 118.090 0.003 5,036.25 976.97 173 0.004 WQCV 5,036.40 1,291.63 334.230 0.008 5,036.60 1,687.08 632.100 0.015 5,036.80 2,095.93 1009.720 0.023 5,037.00 2,996.06 1518.920 0.035 5,037.20 4,245.67 2140.840 0.049 5,037.40 5,334.31 2308.130 0.053 5,037.41 5,060.06 2371 0.054 100-YR DETENTION 5,037.60 1,031.63 3294.490 0.076 NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: SNOW RIDGE APARTMENTS FORT COLLINS | GREELEY APPENDIX APPENDIX B HYDRAULIC CALCULATIONS NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: SNOW RIDGE APARTMENTS FORT COLLINS | GREELEY APPENDIX APPENDIX C WATER QUALITY/LID COMPUTATIONS MBMBMB FO FO OH U OH U OH U OH U OH U OHU OHU FO FO X X X X G G G G E E E 15 " S S SO U T H S H I E L D S S T R E E T DETENTION POND 10.14 ac. A3 0.09 ac. OS2 0.06 ac. OS1 0.15 ac. A2 0.22 ac. A1 a3 a2 a1 PROPOSED 6" PVC UNDERDRAIN @0.2% PAVER 1 PAVER 2 PROPOSED STORM DRAIN DRAWN BY: SCALE: ISSUED: SNOW RIDGE APARTMENTS SHEET NO: FORT COLLINS: 301 North Howes Street, Suite 100, 80521 GREELEY: 820 8th Street, 80631 E N G I N E E R N GI EHTRON R N 970.221.4158 northernengineering.com LID EXHIBIT J. OBanion 1in=30ft 11/15/2023 PROPOSED STORM SEWER PROPOSED CURB & GUTTER PROPERTY BOUNDARY PROPOSED INLET aDESIGN POINT DRAINAGE BASIN LABEL DRAINAGE BASIN BOUNDARY A LEGEND: ( IN FEET ) 1 inch = ft. Feet03030 30 PERMEABLE PAVER LIMITS FOR DRAINAGE REVIEW ONLY NOT FOR CONSTRUCTION On-Site LID Treatment Project Summary Total Impervious Area 13,040 sf Target Treatment Percentage 50% Minimum Area to be Treated by LID measures 6,520 sf Permeable Paver Area Paver 1 Impervious Area 4,586 sf Run-on area for Paver 1 3,029 sf Total Pavers Treatment Area 1,557 sf Impervious Run-on Ratio for Pavers 1 (3:1 Max) 2 :1 Paver 2 Impervious Area 3,360 sf Run-on area for Paver 2 2,185 sf Total Pavers Treatment Area 1,175 sf Impervious Run-on Ratio for Pavers 2 (3:1 Max) 2 :1 Total Treatment Area 7,947 sf Percent Total Project Area Treated 60.9% AREA TREATED BY PAVER 1 AREA TREATED BY PAVER 2 *SEE RATIONAL CALCS FOR IMPERVIOUS AREA CALCULATIONS Project Number:Project: Project Location: Calculations By:Date: Sq. Ft. Acres A1 9,795 0.22 52%n/a Traditional 173 5,093 A2 6,552 0.15 70%Pavers 1 Pavers 120 4,586 A3 5,895 0.14 57%Pavers 2 Pavers 89 3,360 Total 22,242 0.51 13,040 Sq. Ft. Acres Pavers 1 6,552 0.15 70% 4,586 A2 Pavers 120 Pavers 2 5,895 0.14 57% 3,360 A3 Pavers 89 Total 12,447 0.29 7,947 209 Treatment via Traditional Sq. Ft.Acres Pond 1 9,795 0.22 52% 5,093 A1 Extended Detention 173 Total 9,795 0.22 5,093 22,242 ft2 13,040 ft2 6,520 ft2 7,947 ft2 60.94% 5,093 ft2 39.06% 100.00% Tributary Area Weighted % Impervious Required Volume (ft3) LID Summary per Basin Subbasin ID Treatment TypeWQ Treatment Volume per UD-BMP or FAA (ft3) Impervious Area (ft2) Water Quality Treatment via LID LID Summary AreaBasin ID WQ Treatment Type Percent Impervious LID ID Snow Ridge Apartments 11/9/2023 2047-001 Fort Collins, Colorado J. Obanion Total Impervious Area (ft2) Percent Impervious Area Treated by Traditional WQ or LID Total Impervious Area Treated by PICP 50% Required Minimum Area to be Treated by PICP Total Area of Current Development Total Impervious Area Total Impervious Area Treated by Traditional WQ Percent Impervious Treated by Traditional Water Quality WQ Treatment Tributary Area Weighted % Impervious LID Site Summary - New Impervious Area Treatment Type Volume per MHFD- Percent Impervious Treated by PICP Subbasin IDImpervious Area (ft2) Project Title Date: Project Number Calcs By: City Basins 1 WQCV = Watershed inches of Runoff (inches)52% a = Runoff Volume Reduction (constant) i = Total imperviousness Ratio (i = Iwq/100)0.212 in 0.22 ac 0.0040 ac-ft 173 cu. ft. 0.0048 ac-ft 207 cu. ft. V = Water Quality Design Volume (ac-ft) WQCV = Water Quality Capture Volume (inches) A = Watershed Area (acres) V = V (120%) = A = Snow Ridge Apartments November 9, 2023 2047-001 J. Obanion Fort Collins Pond 1 Drain Time a = i = WQCV = Figure EDB-2 - Water Quality Capture Volume (WQCV), 80th Percentile Runoff Event 0.231 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0 0. 1 0. 2 0. 3 0. 4 0. 5 0. 6 0. 7 0. 8 0. 9 1 WQ C V ( w a t e r s h e d i n c h e s ) Total Imperviousness Ratio (i = Iwq/100) Water Quality Capture Volume 6 hr 12 hr 24 hr 40 hr ()iii78.019.10.91aWQCV 23 +-= ()iii78.019.10.91aWQCV 23 +-= AV* 12 WQCV   = 40 hr Sheet 1 of 2 Designer: Company: Date: Project: Location: 1. Type of Permeable Pavement Section A) What type of section of permeable pavement is used? (Based on the land use and activities, proximity to adjacent structures and soil characteristics.) B) What type of wearing course?1 2. Required Storage Volume A) Effective Imperviousness of Area Tributary to Permeable Pavement, Ia Ia =70.0 % B) Tributary Area's Imperviousness Ratio (I = Ia / 100)i = 0.700 C) Tributary Watershed Area ATotal = 6,552 sq ft (including area of permeable pavement system) D) Area of Permeable Pavement System APPS =1,557 sq ft (Minimum recommended permeable pavement area = 1699 sq ft) E) Impervious Tributary Ratio RT =2.2 IMPERVIOUS TRIBUTARY RATIO EXCEEDS 2.0 (Contributing Imperviuos Area / Permeable Pavement Ratio) F) Water Quality Capture Volume (WQCV) Based on 12-hour Drain Time WQCV = 120 cu ft (WQCV = (0.8 * (0.91 * i3 - 1.19 * i2 + 0.78 * i) / 12) * Area) G) Is flood control volume being added? H) Total Volume Needed VTotal =120 cu ft 3. Depth of Reservoir A) Minimum Depth of Reservoir Dmin =10.0 inches (Minimum recommended depth is 6 inches) B) Is the slope of the reservoir/subgrade interface equal to 0%? 2 C) Porosity (Porous Gravel Pavement < 0.3, Others < 0.40) P = 0.30 D) Slope of the Base Course/Subgrade Interface S = 0.002 ft / ft E) Length Between Lateral Flow Barriers (max = 257.19 ft.) L = 150.0 ft F) Volume Provided Based on Depth of Base Course V = 280 cu ft Flat or Stepped: V = P * ((Dmin - 1) / 12) * Area Volume assumes uniform slope & lateral flow barrier spacing Sloped: V = P * ((Dmin - 6*S*L - 1) / 12) * Area Calculate the volume of each cell individually when this varies. 4. Lateral Flow Barriers A) Type of Lateral Flow Barriers B) Number of Permeable Pavement Cells Cells = 5. Perimeter Barrier A) Is a perimeter barrier provided on all sides of the pavement system? (Recommeded for PICP, concrete grid pavement, or for any no-infiltration section.) Snow Ridge Apartments Basin A2 Design Procedure Form: Permeable Pavement Systems (PPS) J. Obanion Northern Engineering November 9, 2023 UD-BMP (Version 3.07, March 2018) Choose One No Infiltration Partial Infiltration Section Full Infiltration Section Choose One YES NO Choose One YES- Flat or Stepped Installation NO- Sloped Installation Choose One Concrete Walls PVC geomembrane installed normal to flow N/A- Flat installation Other (Describe): Choose One YES NO Choose One PICP Concrete Grid Pavement Pervious Concrete Porous Gravel UD-BMP_v3.07-Pavers East, PPS 11/9/2023, 11:48 AM Sheet 2 of 2 Designer: Company: Date: Project: Location: 6. Filter Material and Underdrain System A) Is the underdrain placed below a 6-inch thick layer of CDOT Class C filter material? B) Diameter of Slotted Pipe (slot dimensions per Table PPs-2) C) Distance from the Lowest Elevation of the Storage Volume y = ft (i.e. the bottom of the base course to the center of the orifice) 7. Impermeable Geomembrane Liner and Geotextile Separator Fabric A) Is there a minimum 30 mil thick impermeable PVC geomembrane liner on the bottom and sides of the basin, extending up to the top of the base course? B) CDOT Class B Separator Fabric 8. Outlet 1 (Assumes each cell has similar area, subgrade slope, and length between lateral barriers (unless subgrade is flat). Calculate cells individually where this varies.) A) Depth of WQCV in the Reservoir DWQCV =inches (Elevation of the Flood Control Outlet) B) Diameter of Orifice for 12-hour Drain Time DOrifice =inches (Use a minimum orifice diameter of 3/8-inches) Notes: Snow Ridge Apartments Design Procedure Form: Permeable Pavement Systems (PPS) J. Obanion Northern Engineering November 9, 2023 Basin A2 Choose One YES NO Choose One 4-inch 6-inch Choose One Choose One YES NO Placed above the liner Placed above and below the liner N/A UD-BMP_v3.07-Pavers East, PPS 11/9/2023, 11:48 AM Sheet 1 of 2 Designer: Company: Date: Project: Location: 1. Type of Permeable Pavement Section A) What type of section of permeable pavement is used? (Based on the land use and activities, proximity to adjacent structures and soil characteristics.) B) What type of wearing course?1 2. Required Storage Volume A) Effective Imperviousness of Area Tributary to Permeable Pavement, Ia Ia =57.0 % B) Tributary Area's Imperviousness Ratio (I = Ia / 100)i = 0.570 C) Tributary Watershed Area ATotal = 5,895 sq ft (including area of permeable pavement system) D) Area of Permeable Pavement System APPS =1,175 sq ft (Minimum recommended permeable pavement area = 1307 sq ft) E) Impervious Tributary Ratio RT =2.3 IMPERVIOUS TRIBUTARY RATIO EXCEEDS 2.0 (Contributing Imperviuos Area / Permeable Pavement Ratio) F) Water Quality Capture Volume (WQCV) Based on 12-hour Drain Time WQCV = 89 cu ft (WQCV = (0.8 * (0.91 * i3 - 1.19 * i2 + 0.78 * i) / 12) * Area) G) Is flood control volume being added? H) Total Volume Needed VTotal =89 cu ft 3. Depth of Reservoir A) Minimum Depth of Reservoir Dmin =10.0 inches (Minimum recommended depth is 6 inches) B) Is the slope of the reservoir/subgrade interface equal to 0%? 2 C) Porosity (Porous Gravel Pavement < 0.3, Others < 0.40) P = 0.30 D) Slope of the Base Course/Subgrade Interface S = 0.002 ft / ft E) Length Between Lateral Flow Barriers (max = 252.52 ft.) L = 150.0 ft F) Volume Provided Based on Depth of Base Course V = 212 cu ft Flat or Stepped: V = P * ((Dmin - 1) / 12) * Area Volume assumes uniform slope & lateral flow barrier spacing Sloped: V = P * ((Dmin - 6*S*L - 1) / 12) * Area Calculate the volume of each cell individually when this varies. 4. Lateral Flow Barriers A) Type of Lateral Flow Barriers B) Number of Permeable Pavement Cells Cells = 5. Perimeter Barrier A) Is a perimeter barrier provided on all sides of the pavement system? (Recommeded for PICP, concrete grid pavement, or for any no-infiltration section.) Snow Ridge Apartments Basin A3 Design Procedure Form: Permeable Pavement Systems (PPS) J.Obanion Northern Engineering November 9, 2023 UD-BMP (Version 3.07, March 2018) Choose One No Infiltration Partial Infiltration Section Full Infiltration Section Choose One YES NO Choose One YES- Flat or Stepped Installation NO- Sloped Installation Choose One Concrete Walls PVC geomembrane installed normal to flow N/A- Flat installation Other (Describe): Choose One YES NO Choose One PICP Concrete Grid Pavement Pervious Concrete Porous Gravel UD-BMP_v3.07-Pavers West, PPS 11/9/2023, 11:47 AM Sheet 2 of 2 Designer: Company: Date: Project: Location: 6. Filter Material and Underdrain System A) Is the underdrain placed below a 6-inch thick layer of CDOT Class C filter material? B) Diameter of Slotted Pipe (slot dimensions per Table PPs-2) C) Distance from the Lowest Elevation of the Storage Volume y = ft (i.e. the bottom of the base course to the center of the orifice) 7. Impermeable Geomembrane Liner and Geotextile Separator Fabric A) Is there a minimum 30 mil thick impermeable PVC geomembrane liner on the bottom and sides of the basin, extending up to the top of the base course? B) CDOT Class B Separator Fabric 8. Outlet 1 (Assumes each cell has similar area, subgrade slope, and length between lateral barriers (unless subgrade is flat). Calculate cells individually where this varies.) A) Depth of WQCV in the Reservoir DWQCV =inches (Elevation of the Flood Control Outlet) B) Diameter of Orifice for 12-hour Drain Time DOrifice =inches (Use a minimum orifice diameter of 3/8-inches) Notes: Basin A3 Snow Ridge Apartments Design Procedure Form: Permeable Pavement Systems (PPS) J.Obanion Northern Engineering November 9, 2023 Choose One YES NO Choose One 4-inch 6-inch Choose One Choose One YES NO Placed above the liner Placed above and below the liner N/A UD-BMP_v3.07-Pavers West, PPS 11/9/2023, 11:47 AM NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: SNOW RIDGE APARTMENTS FORT COLLINS | GREELEY APPENDIX APPENDIX D EROSION CONTROL REPORT NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: SNOW RIDGE APARTMENTS FORT COLLINS | GREELEY EROSION CONTROL REPORT EROSION CONTROL REPORT A comprehensive Erosion and Sediment Control Plan (along with associated details) has been included with the final construction drawings. It should be noted; however, 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 and/or wattles 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 Sheet CS2 of the Utility Plans. The Final Utility Plans will also contain a full-size Erosion Control Plan as well as a separate sheet dedicated to Erosion Control Details. In addition to this report and the referenced plan sheets, the Contractor shall be aware of, and adhere to, the applicable requirements outlined in any existing Development Agreement(s) of record, as well as the Development Agreement, to be recorded prior to issuance of the Development Construction Permit. Also, the Site Contractor for this project may be required to secure a Stormwater Construction General Permit from the Colorado Department of Public Health and Environment (CDPHE), Water Quality Control Division – Stormwater Program, before commencing any earth disturbing activities. Prior to securing said permit, the Site Contractor shall develop a comprehensive Storm Water 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. NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: SNOW RIDGE APARTMENTS FORT COLLINS | GREELEY APPENDIX APPENDIX E USDA SOILS REPORT United States Department of Agriculture A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Larimer County Area, Colorado Maxfield Subdivision Lot 2 - 1509 Shields Natural Resources Conservation Service July 7, 2023 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 4—Altvan-Satanta loams, 3 to 9 percent slopes.........................................13 Soil Information for All Uses...............................................................................15 Soil Properties and Qualities..............................................................................15 Soil Erosion Factors........................................................................................15 Wind Erodibility Index..................................................................................15 Wind Erodibility Group.................................................................................18 Soil Qualities and Features.............................................................................21 Hydrologic Soil Group.................................................................................21 References............................................................................................................26 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 44 9 0 7 8 0 44 9 0 7 9 0 44 9 0 8 0 0 44 9 0 8 1 0 44 9 0 8 2 0 44 9 0 8 3 0 44 9 0 8 4 0 44 9 0 8 5 0 44 9 0 7 8 0 44 9 0 7 9 0 44 9 0 8 0 0 44 9 0 8 1 0 44 9 0 8 2 0 44 9 0 8 3 0 44 9 0 8 4 0 44 9 0 8 5 0 491760 491770 491780 491790 491800 491810 491820 491830 491840 491850 491860 491870 491760 491770 491780 491790 491800 491810 491820 491830 491840 491850 491860 40° 34' 6'' N 10 5 ° 5 ' 5 0 ' ' W 40° 34' 6'' N 10 5 ° 5 ' 4 5 ' ' W 40° 34' 3'' N 10 5 ° 5 ' 5 0 ' ' W 40° 34' 3'' N 10 5 ° 5 ' 4 5 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 20 40 80 120 Feet 0 5 10 20 30 Meters Map Scale: 1:507 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 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 17, Sep 7, 2022 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jul 2, 2021—Aug 25, 2021 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Custom Soil Resource Report 10 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 4 Altvan-Satanta loams, 3 to 9 percent slopes 0.7 100.0% Totals for Area of Interest 0.7 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. Custom Soil Resource Report 11 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 4—Altvan-Satanta loams, 3 to 9 percent slopes Map Unit Setting National map unit symbol: jpwf Elevation: 5,200 to 6,200 feet Mean annual precipitation: 13 to 15 inches Mean annual air temperature: 48 to 50 degrees F Frost-free period: 135 to 150 days Farmland classification: Farmland of statewide importance Map Unit Composition Altvan and similar soils:55 percent Satanta and similar soils:35 percent Minor components:10 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Altvan Setting Landform:Fans, benches, terraces Landform position (three-dimensional):Base slope, side slope, tread Down-slope shape:Linear Across-slope shape:Linear Parent material:Mixed alluvium Typical profile H1 - 0 to 9 inches: loam H2 - 9 to 16 inches: clay loam H3 - 16 to 31 inches: loam H4 - 31 to 60 inches: gravelly sand Properties and qualities Slope:6 to 9 percent Depth to restrictive feature:More than 80 inches Drainage class:Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat):Moderately high to high (0.60 to 2.00 in/hr) Depth to water table:More than 80 inches Frequency of flooding:None Frequency of ponding:None Calcium carbonate, maximum content:10 percent Available water supply, 0 to 60 inches: Low (about 5.5 inches) Interpretive groups Land capability classification (irrigated): 4e Land capability classification (nonirrigated): 4e Hydrologic Soil Group: B Ecological site: R067BY008CO - Loamy Slopes Hydric soil rating: No Custom Soil Resource Report 13 Description of Satanta Setting Landform:Structural benches, terraces Landform position (three-dimensional):Side slope, tread Down-slope shape:Linear Across-slope shape:Linear Parent material:Mixed alluvium and/or eolian deposits Typical profile H1 - 0 to 9 inches: loam H2 - 9 to 14 inches: loam H3 - 14 to 60 inches: loam Properties and qualities Slope:3 to 6 percent Depth to restrictive feature:More than 80 inches Drainage class:Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat):Moderately high to high (0.60 to 2.00 in/hr) Depth to water table:More than 80 inches Frequency of flooding:None Frequency of ponding:None Calcium carbonate, maximum content:10 percent Available water supply, 0 to 60 inches: High (about 10.1 inches) Interpretive groups Land capability classification (irrigated): 2e Land capability classification (nonirrigated): 3e Hydrologic Soil Group: B Ecological site: R067BY002CO - Loamy Plains Hydric soil rating: No Minor Components Nunn Percent of map unit:6 percent Ecological site:R067BY002CO - Loamy Plains Hydric soil rating: No Larimer Percent of map unit:4 percent Ecological site:R067BY002CO - Loamy Plains Hydric soil rating: No Custom Soil Resource Report 14 Soil Information for All Uses Soil Properties and Qualities The Soil Properties and Qualities section includes various soil properties and qualities displayed as thematic maps with a summary table for the soil map units in the selected area of interest. A single value or rating for each map unit is generated by aggregating the interpretive ratings of individual map unit components. This aggregation process is defined for each property or quality. Soil Erosion Factors Soil Erosion Factors are soil properties and interpretations used in evaluating the soil for potential erosion. Example soil erosion factors can include K factor for the whole soil or on a rock free basis, T factor, wind erodibility group and wind erodibility index. Wind Erodibility Index The wind erodibility index is a numerical value indicating the susceptibility of soil to wind erosion, or the tons per acre per year that can be expected to be lost to wind erosion. There is a close correlation between wind erosion and the texture of the surface layer, the size and durability of surface clods, rock fragments, organic matter, and a calcareous reaction. Soil moisture and frozen soil layers also influence wind erosion. 15 16 Custom Soil Resource Report Map—Wind Erodibility Index 44 9 0 7 8 0 44 9 0 7 9 0 44 9 0 8 0 0 44 9 0 8 1 0 44 9 0 8 2 0 44 9 0 8 3 0 44 9 0 8 4 0 44 9 0 8 5 0 44 9 0 7 8 0 44 9 0 7 9 0 44 9 0 8 0 0 44 9 0 8 1 0 44 9 0 8 2 0 44 9 0 8 3 0 44 9 0 8 4 0 44 9 0 8 5 0 491760 491770 491780 491790 491800 491810 491820 491830 491840 491850 491860 491870 491760 491770 491780 491790 491800 491810 491820 491830 491840 491850 491860 40° 34' 6'' N 10 5 ° 5 ' 5 0 ' ' W 40° 34' 6'' N 10 5 ° 5 ' 4 5 ' ' W 40° 34' 3'' N 10 5 ° 5 ' 5 0 ' ' W 40° 34' 3'' N 10 5 ° 5 ' 4 5 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 20 40 80 120 Feet 0 5 10 20 30 Meters Map Scale: 1:507 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 Rating Polygons 0 38 48 56 86 134 160 180 220 250 310 Not rated or not available Soil Rating Lines 0 38 48 56 86 134 160 180 220 250 310 Not rated or not available Soil Rating Points 0 38 48 56 86 134 160 180 220 250 310 Not rated or not available Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 17, Sep 7, 2022 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jul 2, 2021—Aug 25, 2021 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 17 Table—Wind Erodibility Index Map unit symbol Map unit name Rating (tons per acre per year) Acres in AOI Percent of AOI 4 Altvan-Satanta loams, 3 to 9 percent slopes 56 0.7 100.0% Totals for Area of Interest 0.7 100.0% Rating Options—Wind Erodibility Index Units of Measure: tons per acre per year Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Wind Erodibility Group A wind erodibility group (WEG) consists of soils that have similar properties affecting their susceptibility to wind erosion in cultivated areas. The soils assigned to group 1 are the most susceptible to wind erosion, and those assigned to group 8 are the least susceptible. Custom Soil Resource Report 18 19 Custom Soil Resource Report Map—Wind Erodibility Group 44 9 0 7 8 0 44 9 0 7 9 0 44 9 0 8 0 0 44 9 0 8 1 0 44 9 0 8 2 0 44 9 0 8 3 0 44 9 0 8 4 0 44 9 0 8 5 0 44 9 0 7 8 0 44 9 0 7 9 0 44 9 0 8 0 0 44 9 0 8 1 0 44 9 0 8 2 0 44 9 0 8 3 0 44 9 0 8 4 0 44 9 0 8 5 0 491760 491770 491780 491790 491800 491810 491820 491830 491840 491850 491860 491870 491760 491770 491780 491790 491800 491810 491820 491830 491840 491850 491860 40° 34' 6'' N 10 5 ° 5 ' 5 0 ' ' W 40° 34' 6'' N 10 5 ° 5 ' 4 5 ' ' W 40° 34' 3'' N 10 5 ° 5 ' 5 0 ' ' W 40° 34' 3'' N 10 5 ° 5 ' 4 5 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 20 40 80 120 Feet 0 5 10 20 30 Meters Map Scale: 1:507 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 Rating Polygons 1 2 3 4 4L 5 6 7 8 Not rated or not available Soil Rating Lines 1 2 3 4 4L 5 6 7 8 Not rated or not available Soil Rating Points 1 2 3 4 4L 5 6 7 8 Not rated or not available Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 17, Sep 7, 2022 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jul 2, 2021—Aug 25, 2021 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 20 Table—Wind Erodibility Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 4 Altvan-Satanta loams, 3 to 9 percent slopes 5 0.7 100.0% Totals for Area of Interest 0.7 100.0% Rating Options—Wind Erodibility Group Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Lower Soil Qualities and Features Soil qualities are behavior and performance attributes that are not directly measured, but are inferred from observations of dynamic conditions and from soil properties. Example soil qualities include natural drainage, and frost action. Soil features are attributes that are not directly part of the soil. Example soil features include slope and depth to restrictive layer. These features can greatly impact the use and management of the soil. Hydrologic Soil Group Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or Custom Soil Resource Report 21 soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Custom Soil Resource Report 22 23 Custom Soil Resource Report Map—Hydrologic Soil Group 44 9 0 7 8 0 44 9 0 7 9 0 44 9 0 8 0 0 44 9 0 8 1 0 44 9 0 8 2 0 44 9 0 8 3 0 44 9 0 8 4 0 44 9 0 8 5 0 44 9 0 7 8 0 44 9 0 7 9 0 44 9 0 8 0 0 44 9 0 8 1 0 44 9 0 8 2 0 44 9 0 8 3 0 44 9 0 8 4 0 44 9 0 8 5 0 491760 491770 491780 491790 491800 491810 491820 491830 491840 491850 491860 491870 491760 491770 491780 491790 491800 491810 491820 491830 491840 491850 491860 40° 34' 6'' N 10 5 ° 5 ' 5 0 ' ' W 40° 34' 6'' N 10 5 ° 5 ' 4 5 ' ' W 40° 34' 3'' N 10 5 ° 5 ' 5 0 ' ' W 40° 34' 3'' N 10 5 ° 5 ' 4 5 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 20 40 80 120 Feet 0 5 10 20 30 Meters Map Scale: 1:507 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 Rating Polygons A A/D B B/D C C/D D Not rated or not available Soil Rating Lines A A/D B B/D C C/D D Not rated or not available Soil Rating Points A A/D B B/D C C/D D Not rated or not available Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 17, Sep 7, 2022 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jul 2, 2021—Aug 25, 2021 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 24 Table—Hydrologic Soil Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 4 Altvan-Satanta loams, 3 to 9 percent slopes B 0.7 100.0% Totals for Area of Interest 0.7 100.0% Rating Options—Hydrologic Soil Group Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Custom Soil Resource Report 25 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 26 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 27 NORTHERNENGINEERING.COM | 970.221.4158 PRELIMINARY DRAINAGE REPORT: SNOW RIDGE APARTMENTS FORT COLLINS | GREELEY APPENDIX MAP PACKET DR1 – HISTORIC DRAINAGE EXHIBIT DR2 – DEVELOPED DRAINAGE EXHIBIT HY D MBMBMB FO FO FO OH U OH U OH U OH U OH U OH U OH U OH U X OHU OHU OHU G FO FO FO X X X X X X G G G G G G G E E E E E 15 " S S 15 " S S 15 " S S 15 " S S 15 " S S 15 " S S 12 " W 12 " W 12 " W 12 " W 12 " W 12 " W SO U T H S H I E L D S S T R E E T LIMITS OF CONVENTIONAL TOPO (TYP.) OFFSITE CONTOURS PROVIDED FOR REFERENCE ONLY a2 0.43 ac. A2 0.24 ac. A1 a1 Sheet SN O W R I D G E A P A R T M E N T S Th e s e d r a w i n g s a r e in s t r u m e n t s o f s e r v i c e pr o v i d e d b y N o r t h e r n En g i n e e r i n g S e r v i c e s , I n c . an d a r e n o t t o b e u s e d f o r an y t y p e o f c o n s t r u c t i o n un l e s s s i g n e d a n d s e a l e d b y a P r o f e s s i o n a l E n g i n e e r i n th e e m p l o y o f N o r t h e r n En g i n e e r i n g S e r v i c e s , I n c . N O T F O R C O N S T R U C T I O N R E V I E W S E T of 12 DR1 HI S T O R I C D R A I N A G E E X H I B I T 11 CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UTILITIES. CALL UTILITY NOTIFICATION CENTER OF COLORADO Know what'sbelow. before you dig.Call R NORTH ( IN FEET ) 1 inch = ft. Feet02020 20 40 60 EXISTING CONTOUR PROPERTY BOUNDARY A DESIGN POINT FLOW ARROW DRAINAGE BASIN LABEL DRAINAGE BASIN BOUNDARY NOTES: 1.REFER TO THE PRELIMINARY DRAINAGE REPORT, DATED NOVEMBER 15, 2023 FOR ADDITIONAL INFORMATION. A LEGEND: FOR DRAINAGE REVIEW ONLY NOT FOR CONSTRUCTION HISTORIC DRAINAGE SUMMARY Design Point Basin ID Total Area (acres) C2 C100 2-Yr Tc (min) 100-Yr Tc (min) Q2 (cfs) Q100 (cfs) HA1 ha1 0.241 0.50 0.62 5.80 5.80 0.33 1.49 HA2 ha2 0.428 0.23 0.28 10.09 10.09 0.21 0.98 total Total 0.669 0.32 0.41 6.98 6.98 0.56 2.53 MBMBMB FO FO FO OH U OH U OH U OH U OH U OH U OH U OH U X OHU OHU OHU G FO FO FO X X X X X X G G G G G G G E E E E E 15 " S S 15 " S S 15 " S S 15 " S S 15 " S S 15 " S S 12 " W 12 " W 12 " W 12 " W 12 " W 12 " W EM GM UGEUGEUGEUGEUGEUGE G G G G G G W F S UD UD UD UD UD UGE H Y D SO U T H S H I E L D S S T R E E T DETENTION POND 1 55 . 5 ' F L - F L DRAINAGE EASEMENT DRAINAGE EASEMENT 0.14 ac. A30.09 ac. OS2 0.06 ac. OS1 0.15 ac. A2 0.22 ac. A1 a3 a2 a1 PROPOSED EMERGENCY SPILLWAY LOCATION PROPOSED POND OUTLET STRUCTURE PROPOSED 6" PVC UNDERDRAIN @0.2% PAVER 1 PROPOSED PERMEABLE INTERLOCKING PAVERS PAVER 2 PROPOSED PERMEABLE INTERLOCKING PAVERS PROPOSED SIDEWALK CHASE PROPOSED SIDEWALK CHASE PROPOSED SIDEWALK CHASE PROPOSED 8' CONCRETE PAN PROPERTY BOUNDARY (TYP.) PROPOSED 2' CONCRETE PAN LIMITS OF CONVENTIONAL TOPO (TYP.) OFFSITE CONTOURS PROVIDED FOR REFERENCE ONLY PROPOSED UNDERDRAIN OUTFALL WITH UPTURNED ELBOW PROPOSED 2' U-CHANNEL 100-YR WSEL100-YR WSEL PROPOSED FESPROPOSED FES PROPOSED STORM DRAIN DRAINAGE EASEMENT DRAINAGE EASEMENT Sheet SN O W R I D G E A P A R T M E N T S Th e s e d r a w i n g s a r e in s t r u m e n t s o f s e r v i c e pr o v i d e d b y N o r t h e r n En g i n e e r i n g S e r v i c e s , I n c . an d a r e n o t t o b e u s e d f o r an y t y p e o f c o n s t r u c t i o n un l e s s s i g n e d a n d s e a l e d b y a P r o f e s s i o n a l E n g i n e e r i n th e e m p l o y o f N o r t h e r n En g i n e e r i n g S e r v i c e s , I n c . N O T F O R C O N S T R U C T I O N R E V I E W S E T of 12 DR2 DR A I N A G E E X H I B I T 12 CALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOU DIG, GRADE, OR EXCAVATE FOR THE MARKING OF UNDERGROUND MEMBER UTILITIES. CALL UTILITY NOTIFICATION CENTER OF COLORADO Know what'sbelow. before you dig.Call R NORTH ( IN FEET ) 1 inch = ft. Feet02020 20 40 60 PROPOSED CONTOUR PROPOSED STORM SEWER PROPOSED SWALE EXISTING CONTOUR PROPOSED CURB & GUTTER PROPERTY BOUNDARY PROPOSED INLET A DESIGN POINT FLOW ARROW DRAINAGE BASIN LABEL DRAINAGE BASIN BOUNDARY PROPOSED SWALE SECTION 11 NOTES: 1.REFER TO THE PRELIMINARY DRAINAGE REPORT, DATED NOVEMBER 15, 2023 FOR ADDITIONAL INFORMATION. A LEGEND: FOR DRAINAGE REVIEW ONLY NOT FOR CONSTRUCTION DEVELOPED DRAINAGE SUMMARY Design Point Basin ID Total Area (acres) C2 C100 2-Yr Tc (min) 100-Yr Tc (min) Q2 (cfs) Q100 (cfs) a1 A1 0.225 0.58 0.72 5.28 5.28 0.37 1.61 a2 A2 0.150 0.74 0.93 5.00 5.00 0.32 1.39 a3 A3 0.135 0.61 0.77 5.80 5.80 0.23 1.03 total Total 0.511 0.63 0.79 5.97 5.97 0.89 4.03 Offsite Basins os1 OS1 0.064 0.45 0.56 5.05 5.05 0.08 0.36 os2 OS2 0.095 0.18 0.22 5.72 5.72 0.05 0.21 total Total 0.159 0.29 0.36 5.05 5.05 0.13 0.57 Detention Summary ID Tributary Area (ac) Weighted Percent Impervious Extended Detention WQV (ac-ft) LID WQV (ac-ft) 100-Year Detention Vol. (ac-ft) 100-Yr Total Pond Volume (ac-ft) 100-Yr Detention WSEL (ft) Final Release Rate (cfs) Pond 1 0.22 52%0.004 N/A 0.050 0.054 5,037.41 0.60 Paver 1 0.15 70%N/A 0.003 N/A N/A N/A N/A Paver 2 0.14 57%N/A 0.002 N/A N/A N/A N/A