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Home My WebLink AboutGATEWAY APARTMENTS - PDP230001 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT PRELIMINARY DRAINAGE REPORT GATEWAY APARTMENTS FORT COLLINS, COLORADO JANUARY 4, 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 FINAL DRAINAGE REPORT: GATEWAY APARTMENTS FORT COLLINS | GREELEY COVER LETTER January 4, 2023 City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, CO 80521 RE: FINAL DRAINAGE REPORT FOR GATEWAY 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 Gateway 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. ADAM BOESE, PE 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 FINAL DRAINAGE REPORT: GATEWAY 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 ........................................................................... 7 CONCLUSIONS ............................................................................................ 10 REFERENCES .............................................................................................. 11 TABLES AND FIGURES FIGURE 1 – VICINITY MAP .................................................................................................1 FIGURE 2 – AERIAL PHOTOGRAPH ...................................................................................2 FIGURE 3 – EXISTING FEMA FLOODPLAINS (PRIOR TO CLOMR/LOMR) ..........................3 FIGURE 4 - EXISTING CITY FLOODPLAINS ........................................................................3 TABLE 1 - FULL SPECTRUM DETENTION SUMMARY ..................................................... 10 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 FINAL DRAINAGE REPORT: GATEWAY APARTMENTS FORT COLLINS | GREELEY 1 | 11 GENERAL LOCATION AND DESCRIPTION A. LOCATION Vicinity Map The Gateway Apartments project site is located in the southeast quarter of Section 16, Township 7 North, Range 68 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 future single-family residential tract within the Gateway at Prospect development area; to the south by Prospect Road; to the east by Boxelder Creek; and to the west by an existing single-family residential area. Boxelder Creek and the Boxelder Creek 100-yr overflow channel run north to south along the eastern boundary adjacent to the project site. B. DESCRIPTION OF PROPERTY The Gateway Apartments are comprised of ±12.49 acres. The site is currently vacant irrigated agricultural land with future proposed backbone infrastructure being designed with the Gateway at Prospect BDR Project. Backbone infrastructure Figure 1 – Vicinity Map NORTHERNENGINEERING.COM | 970.221.4158 FINAL DRAINAGE REPORT: GATEWAY APARTMENTS FORT COLLINS | GREELEY 2 | 11 will be installed prior to or concurrent with this project includes surrounding connector roads, Frontage Road improvements, utilities and detention ponds. The existing groundcover consists of cultivated corn field, grasses, and gravel. The existing on-site runoff generally drains from the north-to-south across flat grades (e.g., <2.00%) into Boxelder Creek and the 100-yr Boxelder Creek overflow channel. From there, the drainage continues through the channel, and ultimately discharging to the Cache La Poudre River. According to the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Soil Survey, a majority of the project site consists of Nunn clay loam and Satanta Variant clay loam which fall into Hydrologic Soil Groups C-D. Boxelder Creek is the only major drainageway within or adjacent to the project site with the exception of remnants of the historic Cooper Slough which exists just off-site to the west. The proposed development will consist of nine multi-family buildings containing a total of 276 units. Other proposed improvements include new asphalt drive aisles, new sidewalks and new landscaping, a clubhouse with pool and a dog park. The proposed land use is Medium Density Residential. This is a permitted use in the Medium- Density Mixed-Use Neighborhood District (MMN). Figure 2 – Aerial Photograph NORTHERNENGINEERING.COM | 970.221.4158 FINAL DRAINAGE REPORT: GATEWAY APARTMENTS FORT COLLINS | GREELEY 3 | 11 C. FLOODPLAIN The subject property is located in a FEMA floodplain but not a City regulatory floodplain. The Gateway at Prospect backbone infrastructure project will be pursuing a CLOMR/LOMR prior to the construction of this project. Figure 3 – Existing FEMA Floodplains (Prior to CLOMR/LOMR) Figure 4 - Existing City Floodplains NORTHERNENGINEERING.COM | 970.221.4158 FINAL DRAINAGE REPORT: GATEWAY APARTMENTS FORT COLLINS | GREELEY 4 | 11 DRAIN BASINS AND SUB-BASINS A. MAJOR BASIN DESCRIPTION 1. The Gateway Apartments project is located within the Boxelder Creek/Cooper Slough Basin. Boxelder Creek/Cooper slough Basin encompasses 265 square miles beginning north of the Colorado/Wyoming border and extending southward into east Fort Collins, ending at the Cache La Poudre River. 2. Improvements along the Boxelder Creek were recently constructed and detailed in the LOMR case number 17-08-1354P. A 100-year overflow channel and box culverts under Prospect Road were constructed as a part of that project. 3. Backbone Infrastructure improvements along Boxelder Creek including regional trail grading, a bridge crossing of Boxelder Creek and detention pond grading and outfalls needed to detain and treat runoff from the Gateway Apartments are currently under review. Jacobs prepared a CLOMR for “Boxelder Creek at Gateway at Prospect” which is currently under review and will need approval from FEMA and City of Fort Collins prior to approval of Gateway Apartments. B. SUB-BASIN DESCRIPTION The project site has two outfall locations. The northern half of the site will outfall to Boxelder Creek and the southern half will out fall to the Boxelder Creek Overflow Channel. The existing subject site drainage has been master-planned by the Gateway at Prospect backbone infrastructure project. The existing condition shall hence be referred to as the proposed master planned condition as described in the Final Drainage Report for Gateway at Prospect dated August 24th, 2022. The Gateway Apartments project resides in two master planned drainage basins, Basin E and Basin F. These basins are further divided into seven sub-basins. The master planned Basins E1-E2 generally flow south towards Detention Pond E. Existing Basins F1-F5 generally drain east towards Detention Basin F. The project site does not receive notable runoff from contiguous off-site properties. DRAINAGE DESIGN CRITERIA A. OPTIONAL PROVISIONS Gateway Apartments will show compliance with the previous report which utilized full spectrum for detention and traditional 40-hour water quality treatment for the site. The use of full spectrum detention is a variance from the City stormwater criteria, but was approved for use with the Gateway backbone infrastructure project. B. STORMWATER MANAGEMENT STRATEGY The overall stormwater management strategy employed with Gateway 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. Gateway Apartments will be reducing runoff by 10% of the historic value via full spectrum. Full spectrum detention is designed to address two limitations of traditional detention. First, it is focused on controlling peak discharges over the full spectrum of runoff events from small, frequent storms up to the 100-year storm event. Second, full spectrum detention facilities produce outflow hydrographs that, other than a small release rate of the excess NORTHERNENGINEERING.COM | 970.221.4158 FINAL DRAINAGE REPORT: GATEWAY APARTMENTS FORT COLLINS | GREELEY 5 | 11 urban runoff volume (EURV), replicate the shape of predevelopment hydrographs. Full spectrum detention modeling shows a reduction of urban runoff peaks to levels similar to predevelopment conditions over an entire watershed, even multiple independent detention facilities. For a thorough, in-depth explanation of full spectrum, please refer to Volume 2, Chapter 12 of the Urban Drainage Stormwater Criteria Manual published by the Mile High Flood District. Gateway 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 an infiltration gallery. 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 in the underground vaults located near the center and towards the east end of the project. Rain Gardens will be utilized as a second water quality treatment BMP located towards the south end of the site. In addition to LID treatment, traditional water quality treatment will be provided within the lower stages of the detention ponds. Step 3 – Stabilize Drainageways. As stated in Section I.B.5, above, the Boxelder Creek drainage is adjacent to the subject site and Gateway Apartments proposes to limit the amount of disturbance to Boxelder Creek. With the previously mentioned backbone infrastructure project doing most of the work required on the streambank for the future City of Fort Collins Regional Trail, storm outfalls and detention areas, Gateway Apartments will have minimal to the streambank. The Gateway Apartments project aims to protect the existing Boxelder Creek by limiting any increases beyond historical flow rates within the creek. By utilizing a combination of full spectrum detention and the resulting “beat the peak” model, the peak discharge from the Gateway Apartments project will be passed before the peak of the creek. As such, the peak discharge from the Gateway Apartments project will not be compounded with peak flow in the creek. Furthermore, this project will pay a one-time stormwater development fee, as well as ongoing monthly utility fess, 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. C. DEVELOPMENT CRITERIA REFERENCE AND CONSTRAINTS The subject property is part of the master-planned drainage plan set by the Gateway at Prospect backbone infrastructure project. The site plan is constrained on the north and west by connector streets, on the east side by Detention Pond F and future City of Fort Collins Regional Trail and on to the south by Detention Pond E all as designed with the Gateway at Prospect project. D. 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 Gateway NORTHERNENGINEERING.COM | 970.221.4158 FINAL DRAINAGE REPORT: GATEWAY APARTMENTS FORT COLLINS | GREELEY 6 | 11 Apartments development. Tabulated 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. Full spectrum detention has been utilized for detention storage calculations. Two separate design storms have been utilized to address distinct drainage scenarios. The first event analyzed is the “Minor,” or “Initial” Storm, which has a 2-year recurrence interval. The second event considered is the “Major Storm,” which has a 100-year recurrence interval. E. HYDRAULIC CRITERIA The drainage facilities proposed with the Gateway Apartments project are designed in accordance with criteria outlined in the Mile High Flood District’s “Urban Storm Drainage Criteria Manual” (UDFCD) and Fort Collins Stormwater Criteria Manual (FCSCM). As stated in Section I.C.1, above, the subject property is located next to a FEMA designated floodplain. F. FLOODPLAIN REGULATIONS COMPLIANCE As previously mentioned, this project is adjacent to a FEMA regulated floodplain with pending CLOMR/LOMR application. No occupied structures are being proposed within the revised floodplain however, Detention Pond F will remain in the revised floodplain. Storm outfalls which are proposed with the Gateway at Prospect project will be located within the floodplain and floodway, and that work will be subject to the applicable floodplain regulations. Construction of these outfalls are not a part of the Gateway Apartments project. Any grading within the floodplain will be subject to applicable floodplain regulations. Despite most of the project not being located within the floodplain, consideration has been given to the floodplain elevations as they relate to the proposed buildings and the finished floors, garages, and HVAC have been elevated accordingly. G. MODIFICATIONS OF CRITERIA Gateway Apartments will be following the requirements as set forth in the Final Drainage Report for Gateway at Prospect and will be utilizing full spectrum detention as laid out by the Mile High Flood Control District as a variance from for the Fort Collins Stormwater Criteria detention requirements. H. 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 through the use of Bioretention (aka - Rain Garden located within Basin E) and two separate underground infiltration galleries (aka – underground chambers located under the drive aisles within Basin F). Both Detention Ponds E and F utilize full Spectrum Detention which will provide standard water quality treatment within the lower stages. Through these methods 100% of the on-site area will be treated for water quality. I. CONFORMANCE WITH LOW IMPACT DEVELOPMENT (LID) The project site will conform with the requirement to treat a minimum of 75% of the proposed impervious surfaces using a LID technique. Please see Appendix C for LID design information, table, and exhibit(s). As shown in the LID table provided in the appendix, 77% of the proposed site impervious area will receive LID treatment, which exceeds the minimum required. On-site LID NORTHERNENGINEERING.COM | 970.221.4158 FINAL DRAINAGE REPORT: GATEWAY APARTMENTS FORT COLLINS | GREELEY 7 | 11 treatment does include treatment for the adjacent roads to the project as required by the Final Drainage Report for Gateway at Prospect. J. SIZING OF LID FACILITIES Infiltration Gallery The Infiltration Galleries were sized by first determining the required water quality capture volume (WQCV) for the contributing Basins. A 12-hour drain time was used in this calculation. Once the WQCV was identified, the minimum number of vaults needed to achieve the minimum WQCV was calculated. This volume includes the adjacent aggregates As a result of all underground vaults being wrapped in a geofabric and the potential constriction of flows that could result from sedimentation in the fabric, the total release rate through the fabric was calculated. This rate was determined by multiplying the vault bottom square footage x 0.35 gpm (manufacturer’s estimated infiltration rate of fabric). A volume calculation utilizing the WQ flow rate into the chamber and the calculated release rate through the fabric was completed. The number of chambers has been increased as needed to confirm that the resulting volume is provided within the empty volume of the underground chambers. This is intended to ensure that the chambers do not become overwhelmed in the water quality storm event before “discharging” flows into the surrounding aggregates. DRAINAGE FACILITY DESIGN A. GENERAL CONCEPT The main objective of the Gateway Apartments drainage design is to maintain existing drainage patterns, while not adversely impacting adjacent properties. There are small offsite flows that pass through the site originating from the three adjacent streets proposed with the Gateway at Prospect backbone infrastructure. Generally, these flows consist of half- right-of-ways of connector streets. Gateway Apartments will be responsible for the LID treatment and water quality of these offsite basins in conformance with the Gateway at Prospect drainage report. 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 seventeen (17) drainage sub-basins, designated as sub-basins E1.1-E1.4, E2, F1.1-F1.8, F2, F3, F4 and F5. The drainage patterns anticipated for the basins are further described below. Sub-Basin E1.1 Sub-basin E1.1 is comprised of a section of Street B and portions of the clubhouse and multi- family development. Drainage is routed to Pond E via storm drains and an inlet in Street B. NORTHERNENGINEERING.COM | 970.221.4158 FINAL DRAINAGE REPORT: GATEWAY APARTMENTS FORT COLLINS | GREELEY 8 | 11 Sub-Basin E1.2 Sub-basin E1.2 is comprised of portions of multifamily development north of the clubhouse including parking and drive isles. Drainage is routed to Pond E via sidewalk chase which flows via drainage pan to Rain Garden 1 where it will be treated for LID. Sub-Basin E1.3 Sub-Basin E1.3 is comprised of portions of the clubhouse, open area and a dog park. Stormwater runoff for this basin will be conveyed via drainage pan to Rain Garden 1 where it will be treated for LID prior to infiltration and release via subdrain to Pond E. Sub-Basin E1.4 Sub-Basin E1.4 is comprised of Detention Pond E. Sub-Basin E2 Sub-Basin E2 is comprised of a section of Street B and open space. Drainage is routed to Pond E via storm drains and an inlet in Street B. Sub-Basin F1.1 Sub-Basin F1.1 is comprised of portions of the multi-family development. Stormwater runoff for this basin will be routed to Stormtech Chambers 1 via storm inlet within the private drive aisles where it will be treated for LID prior to release to Pond F. Sub-Basin F1.2 Sub-Basin F1.2 is comprised of portions of the multi-family development. Stormwater runoff for this basin will be routed to Stormtech Chambers 1 via storm inlet within the private drive aisles where it will be treated for LID prior to release to Pond F. Sub-Basin F1.3 Sub-Basin F1.3 is comprised of portions of the multi-family development. Stormwater runoff for this basin will be routed to Stormtech Chambers 1 via storm inlet within the private drive aisles where it will be treated for LID prior to release to Pond F. Sub-Basin F1.4 Sub-Basin F1.4 is comprised of portions of the multi-family development. Stormwater runoff for this basin will be routed to Pond F via a storm inlet in private drive aisle. Pond F will provide traditional water quality and detention for Basin F1.4. NORTHERNENGINEERING.COM | 970.221.4158 FINAL DRAINAGE REPORT: GATEWAY APARTMENTS FORT COLLINS | GREELEY 9 | 11 Sub-Basin F1.5 Sub-Basin F1.5 is comprised of portions of the multi-family development. Stormwater runoff for this basin will be routed to Stormtech Chambers 2 via storm inlet within the private drive isles where it will be treated for LID prior to release to Pond F. Sub-Basin F1.6 Sub-Basin F1.6 is comprised of portions of the multi-family development. Stormwater runoff for this basin will be routed to Stormtech Chambers 2 via storm inlet within the private drive isles where it will be treated for LID prior to release to Pond F. Sub-Basin F1.7 Sub-Basin F1.7 is comprised of portions of the multi-family development. Stormwater runoff for this basin will be routed to Underground Chambers 2 via storm inlet within the private drive isles where it will be treated for LID prior to release to Pond F. Sub-Basin F1.8 Sub-Basin F1.5 is comprised of portions of the multi-family development, future City of Fort Collins Regional Trail, and Detention Pond F. Stormwater runoff will generally sheet flow into a swale where it will continue through Detention Pond F. Pond F will provide Standard Water Quality Treatment and Detention for Basin F1.7. Sub-Basin F2 Sub-Basin F2 is comprised of a section of Street D and portions of the multi-family development. Stormwater runoff is captured in an inlet in Street D and conveyed through a storm drain and into Stormtech Chambers 2 where it will be treated for LID prior to release into Detention Basin F. Sub-Basin F3 Sub-Basin F3 is comprised of half the right of way for Street E and half of the bridge section spanning Boxelder Creek. Runoff is conveyed through a sidewalk culvert and a swale which will convey the into Pond F. Pond F will provide Standard Water Quality Treatment and Detention for Basin F3. Sub-Basin F4 Sub-Basin F4 is comprised of half the right of way for Street B and portions of the multi-family development. Drainage is routed to Stormtech Chambers 2 via an inlet within Street B and a storm drain where it will be treated for LID prior to release to Detention Basin F. Sub-Basin F5 Sub-Basin F5 is comprised of half the right of way for Street B and open space. Drainage is routed to an existing Rain Garden (LID 3) west of Street B via curb cut and sidewalk chase within Street B. The existing Rain Garden will treat the runoff for LID prior to infiltration or release via subdrain to Detention Pond F. 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 FINAL DRAINAGE REPORT: GATEWAY APARTMENTS FORT COLLINS | GREELEY 10 | 11 B. SPECIFIC DETAILS Gateway Apartments is located near the end of the Boxelder Creek/Cooper Slough Basin and will be discharging into Boxelder Creek. In order to “beat the peak”, full spectrum detention was utilized to size the final detention ponds. Gateway Apartments proposed providing 100-year detention, detaining the EURV, and utilizing extended detention for water quality in conformance with the final drainage report for Gateway at Prospect. Existing Storm line F which runs from Basin F5 to Detention Pond F was designed to convey the 100-yr storm flows from sub-basins F5 and F4. A new manhole installed near Stormtech Chambers 1 will divert the water quality storm to the underground chambers and include a 100-yr overflow weir for the 100-yr event. The proposed combination inlet within Basin F2 on Street D has been sized for the 100-yr storm. A manhole will be provided along the proposed storm line near Stormtech Chambers 2 which will divert the water quality storm to the underground chambers and include a 100-yr overflow weir for the 100-yr event. Landscape drains located adjacent to Building 5 have also been sized for the 100-yr event. Detention Pond Calculations 1. Detention Pond Calculations were done via full spectrum method as described in Volume 2, Chapter 12, Section 3 in the Urban Storm Drainage Criteria Manual. Pond ID Total Storage Volume (ac-ft) WQCV (ac-ft) EURV (ac-ft) Final Release Rate (cfs) Pond E 0.482 0.074 0.134 7.2 Pond F 1.680 0.267 0.526 14.6 Table 1 - Full Spectrum Detention Summary CONCLUSIONS A. COMPLIANCE WITH STANDARDS The detention design proposed with the Gateway Apartments project does not comply with the City of Fort Collins’ Stormwater Criteria Manual but does meet the Mile High Flood District Criteria Manual. However, the City of Fort Collins has approved this variance from the detention NORTHERNENGINEERING.COM | 970.221.4158 FINAL DRAINAGE REPORT: GATEWAY APARTMENTS FORT COLLINS | GREELEY 11 | 11 standards set in the FCSCM. The proposed drainage design does comply with the requirements set forth by the Final Drainage Report for Gateway at Prospect BDR. The drainage design proposed with Gateway Apartments complies with the City of Fort Collins Master Drainage Plan for the Boxelder Basin. There are regulatory floodplains associated with the Gateway Apartments development. The drainage plan and stormwater management measures proposed with the Gateway 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. Gateway Apartments utilized full spectrum detention as a mechanism to “beat the peak” of Boxelder Creek. The proposed Gateway Apartments development will not impact the Master Drainage Plan recommendations for the Boxelder major drainage basin. 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. NORTHERNENGINEERING.COM | 970.221.4158 FINAL DRAINAGE REPORT: GATEWAY APARTMENTS FORT COLLINS | GREELEY APPENDIX APPENDIX A HYDROLOGIC COMPUTATIONS CHARACTER OF SURFACE1: Percentage Impervious 2-yr Runoff Coefficient Developed Asphalt .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………100%0.95 Concrete .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………100%0.95 Rooftop .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………90%0.95 Gravel .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………40%0.50 Pavers .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………40%0.50 Public Right of Way .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………90%0.95 Landscape or Pervious Surface Playgrounds .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………25%0.35 Lawns Clayey Soil .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………2%0.25 Lawns Sandy Soil .…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..……………………………………………….…………………………..………………………………………………2%0.15 Notes: Basin ID Basin Area (ac) Area of Asphalt (ac) Area of Concrete (ac) Area of Rooftop (ac) Area of Public ROW (ac) Area of Gravel (ac) Area of Pavers (ac) Area of Playgrounds (ac) Area of Lawns (ac) Composite % Imperv. Impervious Area (ac) 2-year Composite Runoff Coefficient 10-year Composite Runoff Coefficient CxCf Cf=1.00 100-year Composite Runoff Coefficient CxCf Cf=1.25 Notes F1.1 1.50 0.53 0.26 0.56 0.00 0.00 0.00 0.00 0.16 86% 1.29 0.88 0.88 1.00 F1.2 1.31 0.46 0.25 0.50 0.00 0.00 0.00 0.00 0.09 89% 1.16 0.90 0.90 1.00 F1.3 0.91 0.29 0.09 0.45 0.00 0.00 0.00 0.00 0.08 87% 0.79 0.89 0.89 1.00 F1.4 1.32 0.43 0.35 0.21 0.00 0.00 0.00 0.00 0.32 75% 0.99 0.78 0.78 0.98 F1.5 0.30 0.00 0.02 0.12 0.00 0.00 0.00 0.00 0.17 41% 0.12 0.56 0.56 0.70 F1.6 0.88 0.20 0.16 0.45 0.00 0.00 0.00 0.00 0.07 87% 0.77 0.89 0.89 1.00 F1.7 0.71 0.31 0.10 0.24 0.00 0.00 0.00 0.00 0.06 88% 0.62 0.89 0.89 1.00 F1.8 1.72 0.00 0.05 0.18 0.00 0.00 0.00 0.00 1.49 14% 0.24 0.34 0.34 0.43 F2 0.58 0.00 0.00 0.08 0.44 0.00 0.00 0.00 0.06 80% 0.47 0.87 0.87 1.00 F3 0.35 0.00 0.00 0.00 0.35 0.00 0.00 0.00 0.00 90% 0.32 0.95 0.95 1.00 F4 1.43 0.00 0.02 0.26 0.79 0.00 0.00 0.00 0.36 68% 0.97 0.77 0.77 0.96 F5 1.21 0.00 0.00 0.00 0.52 0.00 0.00 0.00 0.69 40% 0.48 0.55 0.55 0.69 LID 3 - Rain Garden F5 E1.1 0.50 0.00 0.01 0.07 0.32 0.00 0.00 0.00 0.10 73% 0.37 0.81 0.81 1.00 E1.2 1.20 0.59 0.17 0.14 0.00 0.01 0.00 0.00 0.28 75% 0.90 0.78 0.78 0.98 E1.3 1.03 0.00 0.33 0.13 0.00 0.06 0.00 0.00 0.52 46% 0.47 0.57 0.57 0.71 E1.4 0.69 0.00 0.00 0.00 0.04 0.00 0.00 0.00 0.65 7% 0.05 0.29 0.29 0.36 E2 0.80 0.00 0.12 0.00 0.30 0.00 0.00 0.00 0.38 50% 0.40 0.62 0.62 0.78 Combined Basins F1.1 to F1.8, F2 to F5 12.21 2.22 1.31 3.04 2.10 0.00 0.00 0.00 3.54 67%8.18 0.75 0.75 0.94 Tributary Detention Pond F F1.1 to F1.3, F4 5.14 1.28 0.62 1.76 0.79 0.00 0.00 0.00 0.68 82%4.22 0.86 0.86 1.00 LID 1 - Stormtech Chambers 1 F1.5 to F1.7, F2 2.47 0.50 0.29 0.89 0.44 0.00 0.00 0.00 0.36 80%1.98 0.85 0.85 1.00 LID 2 - Stormtech Chambers 2 E1.1 to E1.4, E2 4.22 0.59 0.64 0.33 0.65 0.07 0.00 0.00 1.93 52%2.19 0.62 0.62 0.78 Tributary Detention Pond E E1.2 to E1.3 2.23 0.59 0.50 0.26 0.00 0.07 0.00 0.00 0.80 62%1.38 0.68 0.68 0.85 LID 4 - Rain Garden 1 10.41 4.22 1.98 0.48 77% 1.38 8.06 2) Runoff Coefficients are taken from the Fort Collins Stormwater Criteria Manual, Chapter 3. Table 3.2-1 and 3.2-2 Low Impact Development Summary LID 1 Treated Impervious Acres (Ac) = LID 2 Treated Impervious Acres (Ac) = 1) Percentage impervious taken from the Fort Collins Stormwater Criteria Manual, Chapter 5, Table 4.1-2 and Table 4.1-3 DEVELOPED BASIN % IMPERVIOUSNESS AND RUNOFF COEFFICIENT CALCULATIONS Total LID Treated Impervious Acres (Ac) = Total Site Impervious Acres (Ac) = Percentage of Impervious Acres Treated with LID (Ac) = LID 3 Treated Impervious Acres (Ac) = LID 4 Treated Impervious Acres (Ac) = Overland Flow, Time of Concentration: Channelized Flow, Time of Concentration: Total Time of Concentration : T c is the lesser of the values of Tc calculated using T c = T i + T t C2 C100 Length, L (ft) Slope, S (%) Ti2 Ti100 Length, L (ft) Slope, S (%) Roughness Coefficient Assumed Hydraulic Radius Velocity, V (ft/s) Tt (min)Tc (Eq. 3.3-5) Tc2 = Ti +Tt Tc100 = Ti +Tt Tc2 Tc100 f1.1 F1.1 0.88 1.00 91 2.64%2.8 1.3 394 0.87%0.015 0.15 2.61 2.5 12.7 5.4 3.8 5.4 5.0 f1.2 F1.2 0.90 1.00 81 4.31%2.1 1.0 386 0.66%0.015 0.15 2.28 2.8 12.6 4.9 3.9 5.0 5.0 f1.3 F1.3 0.89 1.00 95 1.88%3.1 1.5 204 0.47%0.015 0.15 1.91 1.8 11.7 4.9 3.3 5.0 5.0 f1.4 F1.4 0.78 0.98 62 2.26%3.6 1.4 290 1.58%0.015 0.15 3.52 1.4 12.0 5.0 2.8 5.0 5.0 f1.5 F1.5 0.56 0.70 39 4.97%3.7 2.7 N/A 0.015 0.15 N/A N/A 10.2 3.7 2.7 5.0 5.0 f1.6 F1.6 0.89 1.00 70 2.30%2.5 1.2 294 0.70%0.015 0.15 2.35 2.1 12.0 4.6 3.3 5.0 5.0 f1.7 F1.7 0.89 1.00 96 3.33%2.6 1.2 231 0.71%0.015 0.15 2.37 1.6 11.8 4.2 2.9 5.0 5.0 f1.8 F1.8 0.34 0.43 N/A N/A N/A 488 1.52%0.015 0.15 3.46 2.3 N/A 2.3 2.3 5.0 5.0 f2 F2 0.87 1.00 20 2.67%1.4 0.6 332 0.48%0.015 0.15 1.93 2.9 12.0 4.2 3.5 5.0 5.0 f3 F3 0.95 1.00 25 1.88%1.1 0.8 326 1.06%0.015 0.15 2.89 1.9 12.0 3.0 2.6 5.0 5.0 f4 F4 0.77 0.96 19 2.50%2.0 0.8 665 0.72%0.015 0.15 2.38 4.7 13.8 6.6 5.5 6.6 5.5 f5 F5 0.55 0.69 20 2.78%3.3 2.4 556 0.69%0.015 0.15 2.34 4.0 13.2 7.2 6.4 7.2 6.4 e1.1 E1.1 0.81 1.00 21 2.71%1.8 0.6 351 1.48%0.015 0.15 3.41 1.7 12.1 3.5 2.3 5.0 5.0 e1.2 E1.2 0.78 0.98 90 4.39%3.5 1.4 325 0.82%0.015 0.15 2.54 2.1 12.3 5.6 3.5 5.6 5.0 e1.3 E1.3 0.57 0.71 186 1.95%10.8 7.9 186 1.12%0.015 0.15 2.97 1.0 12.1 11.9 9.0 11.9 9.0 e1.4 E1.4 0.29 0.36 66 7.74%6.2 5.7 199 0.50%0.015 0.15 1.98 1.7 11.5 7.9 7.3 7.9 7.3 e2 E2 0.62 0.78 22 2.18%3.2 2.2 341 1.52%0.015 0.15 3.45 1.6 12.0 4.9 3.8 5.0 5.0 f1.8 F1.1 to F1.8, F2 to F5 0.75 0.94 91 2.64%4.5 2.1 997 1.01%0.015 0.15 2.82 5.9 16.0 10.4 8.0 10.4 8.0 f1.3 F1.1 to F1.3, F4 0.86 1.00 91 2.64%3.1 1.3 394 0.87%0.015 0.15 2.61 2.5 12.7 5.6 3.8 5.6 5.0 f1.7 F1.5 to F1.7, F2 0.85 1.00 70 2.30%3.0 1.2 294 0.70%0.015 0.15 2.35 2.1 12.0 5.1 3.3 5.1 5.0 e1.4 E1.1 to E1.4, E2 0.62 0.78 90 4.39%5.2 3.5 429 1.17%0.015 0.15 3.04 2.4 12.9 7.6 5.9 7.6 5.9 e1.3 E1.2 to E1.3 0.68 0.85 90 4.39%4.6 2.7 429 1.17%0.015 0.15 3.04 2.4 12.9 6.9 5.1 6.9 5.1 Combined Basins DEVELOPED DIRECT TIME OF CONCENTRATION Channelized Flow Design Point Basin Overland Flow Time of Concentration Frequency Adjustment Factor: (Equation 3.3-2 FCSCM) (Equation 5-5 FCSCM) (Equation 5-4 FCSCM) (Equation 3.3-5 FCSCM) Table 3.2-3 FCSCM Therefore Tc2=Tc10 Notes: 1) Add 5000 to all elevations. 2) Per Fort Collins Stormwater Manual, minimum Tc = 5 min. 3) Assume a water depth of 6" and a typical curb and gutter per Larimer County Urban Street Standard Detail 701 for curb and gutter channelized flow. Assume a water depth of 1', fixed side slopes, and a triangular swale section for grass channelized flow. Assume a water depth of 1', 4:1 side slopes, and a 2' wide valley pan for channelized flow in a valley pan. Rational Method Equation: Rainfall Intensity: f1.1 F1.1 1.50 5.4 5.0 0.88 1.00 2.85 4.87 9.95 3.76 6.43 14.92 f1.2 F1.2 1.31 5.0 5.0 0.90 1.00 2.85 4.87 9.95 3.36 5.74 13.02 f1.3 F1.3 0.91 5.0 5.0 0.89 1.00 2.85 4.87 9.95 2.30 3.92 9.01 f1.4 F1.4 1.32 5.0 5.0 0.78 0.98 2.85 4.87 9.95 2.93 5.01 12.79 f1.5 F1.5 0.30 5.0 5.0 0.56 0.70 2.85 4.87 9.95 0.48 0.82 2.09 f1.6 F1.6 0.88 5.0 5.0 0.89 1.00 2.85 4.87 9.95 2.24 3.82 8.78 f1.7 F1.7 0.71 5.0 5.0 0.89 1.00 2.85 4.87 9.95 1.80 3.08 7.07 f1.8 F1.8 1.72 5.0 5.0 0.34 0.43 2.85 4.87 9.95 1.67 2.85 7.27 f2 F2 0.58 5.0 5.0 0.87 1.00 2.85 4.87 9.95 1.44 2.47 5.79 f3 F3 0.35 5.0 5.0 0.95 1.00 2.85 4.87 9.95 0.95 1.63 3.51 f4 F4 1.43 6.6 5.5 0.77 0.96 2.60 4.44 9.06 2.86 4.88 12.46 f5 F5 1.21 7.2 6.4 0.55 0.69 2.52 4.31 8.80 1.67 2.86 7.30 e1.1 E1.1 0.50 5.0 5.0 0.81 1.00 2.85 4.87 9.95 1.15 1.97 4.98 e1.2 E1.2 1.20 5.6 5.0 0.78 0.98 2.76 4.72 9.63 2.58 4.41 11.25 e1.3 E1.3 1.03 11.9 9.0 0.57 0.71 2.09 3.57 7.29 1.22 2.09 5.34 e1.4 E1.4 0.69 7.9 7.3 0.29 0.36 2.46 4.21 8.59 0.49 0.84 2.15 e2 E2 0.80 5.0 5.0 0.62 0.78 2.85 4.87 9.95 1.42 2.42 6.19 f1.8 F1.1 to F1.8, F2 to F5 12.21 10.4 8.0 0.75 0.94 2.21 2.21 7.72 20.24 20.24 88.39 f1.3 F1.1 to F1.3, F4 5.14 5.6 5.0 0.86 1.00 2.76 2.76 9.63 12.21 12.21 49.52 f1.7 F1.5 to F1.7, F2 2.47 5.1 5.0 0.85 1.00 2.85 2.85 9.95 5.99 5.99 24.61 e1.4 E1.1 to E1.4, E2 4.22 7.6 5.9 0.62 0.78 2.46 2.46 8.59 6.43 6.43 28.08 e1.3 E1.2 to E1.3 2.23 6.9 5.1 0.68 0.85 2.60 2.60 9.06 3.93 3.93 17.13 Combined Basins DEVELOPED RUNOFF COMPUTATIONS Design Point Basin(s)Area, A (acres) Tc2 (min) Flow, Q2 (cfs) Flow, Q100 (cfs) C2 C100 IDF Table for Rational Method - Table 3.4-1 FCSCM Intensity, i10 (in/hr) Flow, Q10 (cfs) Tc100 (min) Intensity, i2 (in/hr) Intensity, i100 (in/hr) ()()()AiCCQf= Project: Basin ID: Depth Increment = ft Watershed Information Top of Micropool -- 0.00 -- -- -- 169 0.004 Selected BMP Type =EDB -- 0.20 -- -- -- 1,054 0.024 122 0.003 Watershed Area = 4.22 acres -- 0.40 -- -- -- 1,979 0.045 426 0.010 Watershed Length = 469 ft -- 0.60 -- -- -- 3,061 0.070 930 0.021 Watershed Length to Centroid = 230 ft -- 0.80 -- -- -- 4,212 0.097 1,657 0.038 Watershed Slope = 0.015 ft/ft -- 1.00 -- -- -- 5,446 0.125 2,623 0.060 Watershed Imperviousness = 52.00% percent -- 1.20 -- -- -- 6,155 0.141 3,783 0.087 Percentage Hydrologic Soil Group A = 0.0% percent -- 1.40 -- -- -- 6,799 0.156 5,078 0.117 Percentage Hydrologic Soil Group B = 0.0% percent -- 1.60 -- -- -- 7,454 0.171 6,429 0.148 Percentage Hydrologic Soil Groups C/D = 100.0% percent -- 1.80 -- -- -- 8,117 0.186 7,979 0.183 Target WQCV Drain Time = 40.0 hours -- 2.00 -- -- -- 8,790 0.202 9,663 0.222 Location for 1-hr Rainfall Depths = Thornton - Civic Center -- 2.20 -- -- -- 9,473 0.217 11,483 0.264 -- 2.40 -- -- -- 10,171 0.233 13,542 0.311 -- 2.60 -- -- -- 10,877 0.250 15,647 0.359 Optional User Overrides -- 2.80 -- -- -- 11,590 0.266 17,893 0.411 Water Quality Capture Volume (WQCV) = 0.074 acre-feet acre-feet -- 3.00 -- -- -- 12,311 0.283 20,283 0.466 Excess Urban Runoff Volume (EURV) = 0.208 acre-feet acre-feet -- 3.20 -- -- -- 13,024 0.299 22,817 0.524 2-yr Runoff Volume (P1 = 0.82 in.) = 0.129 acre-feet 0.82 inches -- 3.40 -- -- -- 13,726 0.315 25,492 0.585 5-yr Runoff Volume (P1 = 1.14 in.) = 0.208 acre-feet 1.14 inches -- 3.60 -- -- -- 14,415 0.331 28,306 0.650 10-yr Runoff Volume (P1 = 1.4 in.) = 0.288 acre-feet 1.40 inches -- 3.80 -- -- -- 15,109 0.347 31,259 0.718 25-yr Runoff Volume (P1 = 1.81 in.) = 0.439 acre-feet 1.81 inches -- 4.00 -- -- -- 15,806 0.363 34,350 0.789 50-yr Runoff Volume (P1 = 2.27 in.) = 0.598 acre-feet 2.27 inches -- 4.20 -- -- -- 16,509 0.379 37,582 0.863 100-yr Runoff Volume (P1 = 2.86 in.) = 0.815 acre-feet 2.86 inches -- 4.40 -- -- -- 17,217 0.395 40,954 0.940 500-yr Runoff Volume (P1 = 4.39 in.) = 1.367 acre-feet 4.39 inches -- 4.60 -- -- -- 17,941 0.412 44,470 1.021 Approximate 2-yr Detention Volume = 0.127 acre-feet -- 4.80 -- -- -- 18,665 0.428 48,131 1.105 Approximate 5-yr Detention Volume = 0.207 acre-feet -- 5.80 -- -- -- 22,285 0.512 68,606 1.575 Approximate 10-yr Detention Volume = 0.248 acre-feet -- -- -- -- Approximate 25-yr Detention Volume = 0.303 acre-feet -- -- -- -- Approximate 50-yr Detention Volume = 0.350 acre-feet -- -- -- -- Approximate 100-yr Detention Volume = 0.445 acre-feet -- -- -- -- -- -- -- -- Define Zones and Basin Geometry -- -- -- -- Zone 1 Volume (WQCV) = 0.074 acre-feet -- -- -- -- Zone 2 Volume (EURV - Zone 1) = 0.134 acre-feet -- -- -- -- Zone 3 (100yr + 1 / 2 WQCV - Zones 1 & 2) = 0.274 acre-feet -- -- -- -- Total Detention Basin Volume = 0.482 acre-feet -- -- -- -- Initial Surcharge Volume (ISV) = user ft 3 -- -- -- -- Initial Surcharge Depth (ISD) = user ft -- -- -- -- Total Available Detention Depth (Htotal) = user ft -- -- -- -- Depth of Trickle Channel (HTC) = user ft -- -- -- -- Slope of Trickle Channel (STC) = user ft/ft -- -- -- -- Slopes of Main Basin Sides (Smain) = user H:V -- -- -- -- Basin Length-to-Width Ratio (RL/W) = user -- -- -- -- -- -- -- -- Initial Surcharge Area (AISV) =user ft 2 -- -- -- -- Surcharge Volume Length (LISV) =user ft -- -- -- -- Surcharge Volume Width (WISV) =user ft -- -- -- -- Depth of Basin Floor (HFLOOR) =user ft -- -- -- -- Length of Basin Floor (LFLOOR) =user ft -- -- -- -- Width of Basin Floor (WFLOOR) =user ft -- -- -- -- Area of Basin Floor (AFLOOR) =user ft 2 -- -- -- -- Volume of Basin Floor (VFLOOR) =user ft 3 -- -- -- -- Depth of Main Basin (HMAIN) =user ft -- -- -- -- Length of Main Basin (LMAIN) =user ft -- -- -- -- Width of Main Basin (WMAIN) =user ft -- -- -- -- Area of Main Basin (AMAIN) =user ft 2 -- -- -- -- Volume of Main Basin (VMAIN) =user ft 3 -- -- -- -- Calculated Total Basin Volume (Vtotal) =user acre-feet -- -- -- -- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- DETENTION BASIN STAGE-STORAGE TABLE BUILDER Optional Override Area (ft 2) Length (ft) Optional Override Stage (ft) Stage (ft) Stage - Storage Description Area (ft 2) Width (ft) Gateway apartments Pond E MHFD-Detention, Version 4.06 (July 2022) Volume (ft 3) Volume (ac-ft) Area (acre) After providing required inputs above including 1-hour rainfall depths, click 'Run CUHP' to generate runoff hydrographs using the embedded Colorado Urban Hydrograph Procedure. ExampleZone Configuration (Retention Pond) 1719-002_MHFD-Detention_v4-06 Pond E - Full Spectrum Detention, Basin 11/11/2022, 12:01 PM 1 User Defined Stage-Area Booleans for Message 1 Equal Stage-Area Inputs Watershed L:W 1 CountA Watershed Lc:L Watershed Slope 0 Calc_S_TC Booleans for CUHP 1 CUHP Inputs Complete H_FLOOR 1 CUHP Results Calculated L_FLOOR_OTHER 0.00 ISV 0.00 ISV 0.00 Floor 0.00 Floor 1.12 Zone 1 (WQCV) 1.12 Zone 1 (WQCV) 1.93 Zone 2 (EURV) 1.93 Zone 2 (EURV) 3.06 Z3 (100+1/2WQCV)3.06 Z3 (100+1/2WQCV) DETENTION BASIN STAGE-STORAGE TABLE BUILDER MHFD-Detention, Version 4.06 (July 2022) 0.000 0.395 0.790 1.185 1.580 0.000 0.130 0.260 0.390 0.520 0.00 1.50 3.00 4.50 6.00 Volume (ac-ft)Area (acres)Stage (ft.) Area (acres)Volume (ac-ft) 0 5600 11200 16800 22400 0 5 10 15 20 0.00 1.50 3.00 4.50 6.00 Area (sq.ft.)Length, Width (ft.)Stage (ft) Length (ft)Width (ft)Area (sq.ft.) 1719-002_MHFD-Detention_v4-06 Pond E - Full Spectrum Detention, Basin 11/11/2022, 12:01 PM Project: Basin ID: Estimated Estimated Stage (ft) Volume (ac-ft) Outlet Type Zone 1 (WQCV) 1.12 0.074 Orifice Plate Zone 2 (EURV) 1.93 0.134 Orifice Plate Z3 (100+1/2WQCV) 3.06 0.274 Weir&Pipe (Restrict) Total (all zones) 0.482 User Input: Orifice at Underdrain Outlet (typically used to drain WQCV in a Filtration BMP)Calculated Parameters for Underdrain Underdrain Orifice Invert Depth = N/A ft (distance below the filtration media surface) Underdrain Orifice Area = N/A ft2 Underdrain Orifice Diameter = N/A inches Underdrain Orifice Centroid = N/A feet User Input: Orifice Plate with one or more orifices or Elliptical Slot Weir (typically used to drain WQCV and/or EURV in a sedimentation BMP)Calculated Parameters for Plate Centroid of Lowest Orifice = 0.00 ft (relative to basin bottom at Stage = 0 ft) WQ Orifice Area per Row =5.000E-03 ft2 Depth at top of Zone using Orifice Plate = 2.00 ft (relative to basin bottom at Stage = 0 ft) Elliptical Half-Width = N/A feet Orifice Plate: Orifice Vertical Spacing = 8.00 inches Elliptical Slot Centroid = N/A feet Orifice Plate: Orifice Area per Row = 0.72 sq. inches (diameter = 15/16 inch)Elliptical Slot Area = N/A ft2 User Input: Stage and Total Area of Each Orifice Row (numbered from lowest to highest) Row 1 (required) Row 2 (optional) Row 3 (optional) Row 4 (optional) Row 5 (optional) Row 6 (optional) Row 7 (optional) Row 8 (optional) Stage of Orifice Centroid (ft) 0.00 0.70 1.40 Orifice Area (sq. inches) 0.72 0.72 0.72 0.72 Row 9 (optional) Row 10 (optional) Row 11 (optional) Row 12 (optional) Row 13 (optional) Row 14 (optional) Row 15 (optional) Row 16 (optional) Stage of Orifice Centroid (ft) Orifice Area (sq. inches) User Input: Vertical Orifice (Circular or Rectangular)Calculated Parameters for Vertical Orifice Not Selected Not Selected Not Selected Not Selected Invert of Vertical Orifice = N/A N/A ft (relative to basin bottom at Stage = 0 ft) Vertical Orifice Area =N/A N/A ft2 Depth at top of Zone using Vertical Orifice = N/A N/A ft (relative to basin bottom at Stage = 0 ft) Vertical Orifice Centroid = N/A N/A feet Vertical Orifice Diameter = N/A N/A inches User Input: Overflow Weir (Dropbox with Flat or Sloped Grate and Outlet Pipe OR Rectangular/Trapezoidal Weir and No Outlet Pipe) Calculated Parameters for Overflow Weir grate Zone 3 Weir Not Selected Zone 3 Weir Not Selected Overflow Weir Front Edge Height, Ho = 2.20 N/A ft (relative to basin bottom at Stage = 0 ft)Height of Grate Upper Edge, Ht =3.20 N/A feet Overflow Weir Front Edge Length = 4.00 N/A feet Overflow Weir Slope Length = 5.10 N/A feet Overflow Weir Grate Slope = 5.00 N/A H:V Grate Open Area / 100-yr Orifice Area = 14.72 N/A Horiz. Length of Weir Sides = 5.00 N/A feet Overflow Grate Open Area w/o Debris = 14.20 N/A ft2 Overflow Grate Type = Type C Grate N/A Overflow Grate Open Area w/ Debris = 14.20 N/A ft2 Debris Clogging % = 0% N/A % User Input: Outlet Pipe w/ Flow Restriction Plate (Circular Orifice, Restrictor Plate, or Rectangular Orifice)Calculated Parameters for Outlet Pipe w/ Flow Restriction Plate Zone 3 Restrictor Not Selected Zone 3 Restrictor Not Selected Depth to Invert of Outlet Pipe = 0.00 N/A ft (distance below basin bottom at Stage = 0 ft)Outlet Orifice Area = 0.96 N/A ft2 Outlet Pipe Diameter = 15.00 N/A inches Outlet Orifice Centroid = 0.51 N/A feet Restrictor Plate Height Above Pipe Invert = 11.00 inches Half-Central Angle of Restrictor Plate on Pipe =2.06 N/A radians User Input: Emergency Spillway (Rectangular or Trapezoidal)Calculated Parameters for Spillway Spillway Invert Stage= 4.96 ft (relative to basin bottom at Stage = 0 ft) Spillway Design Flow Depth= 0.30 feet Spillway Crest Length = 24.00 feet Stage at Top of Freeboard = 5.76 feet Spillway End Slopes = 20.00 H:V Basin Area at Top of Freeboard = 0.51 acres Freeboard above Max Water Surface = 0.50 feet Basin Volume at Top of Freeboard = 1.55 acre-ft Max Ponding Depth of Target Storage Volume =2.90 feet Discharge at Top of Freeboard = 89.64 cfs Routed Hydrograph Results Design Storm Return Period =WQCV EURV 2 Year 5 Year 10 Year 25 Year 50 Year 100 Year 500 Year One-Hour Rainfall Depth (in) =N/A N/A 0.82 1.14 1.40 1.81 2.27 2.86 4.39 CUHP Runoff Volume (acre-ft) =0.074 0.208 0.129 0.208 0.288 0.439 0.598 0.815 1.367 Inflow Hydrograph Volume (acre-ft) =N/A N/A 0.129 0.208 0.288 0.439 0.598 0.815 1.367 CUHP Predevelopment Peak Q (cfs) =N/A N/A 0.0 0.7 1.6 3.8 5.7 8.3 14.7 OPTIONAL Override Predevelopment Peak Q (cfs) =N/A N/A Predevelopment Unit Peak Flow, q (cfs/acre) =N/A N/A 0.01 0.16 0.37 0.89 1.35 1.97 3.49 Peak Inflow Q (cfs) =N/A N/A 2.3 3.8 5.3 8.2 11.1 15.2 24.7 Peak Outflow Q (cfs) =0.0 0.1 0.1 0.1 0.1 1.9 4.3 7.2 8.5 Ratio Peak Outflow to Predevelopment Q =N/A N/A N/A 0.1 0.1 0.5 0.8 0.9 0.6 Structure Controlling Flow =Plate Plate Plate Plate Overflow Weir 1 Overflow Weir 1 Overflow Weir 1 Outlet Plate 1 Outlet Plate 1 Max Velocity through Grate 1 (fps) =N/A N/A N/A N/A 0.0 0.1 0.3 0.5 0.6 Max Velocity through Grate 2 (fps) =N/A N/A N/A N/A N/A N/A N/A N/A N/A Time to Drain 97% of Inflow Volume (hours) =37 61 50 62 71 68 65 61 53 Time to Drain 99% of Inflow Volume (hours) =39 65 53 66 76 75 74 72 68 Maximum Ponding Depth (ft) =1.11 1.93 1.43 1.86 2.23 2.50 2.68 2.90 3.88 Area at Maximum Ponding Depth (acres) =0.13 0.20 0.16 0.19 0.22 0.24 0.26 0.27 0.35 Maximum Volume Stored (acre-ft) =0.074 0.210 0.120 0.196 0.272 0.335 0.379 0.438 0.746 The user can override the default CUHP hydrographs and runoff volumes by entering new values in the Inflow Hydrographs table (Columns W through AF). DETENTION BASIN OUTLET STRUCTURE DESIGN MHFD-Detention, Version 4.06 (July 2022) Gateway apartments Pond E Example Zone Configuration (Retention Pond) 1719-002_MHFD-Detention_v4-06 Pond E - Full Spectrum Detention, Outlet Structure 11/11/2022, 12:01 PM COUNTA for Basin Tab = 1 Ao Dia WQ Plate Type Vert Orifice 1Vert Orifice 2 Count_Underdrain = 0 0.11(diameter = 3/8 inch)2 1 1 Count_WQPlate = 1 0.14(diameter = 7/16 inch) Count_VertOrifice1 = 0 0.18(diameter = 1/2 inch)Outlet Plate 1 Outlet Plate 2 Drain Time Message Boolean Count_VertOrifice2 = 0 0.24(diameter = 9/16 inch)4 1 5yr, <72hr 0 Count_Weir1 = 1 0.29(diameter = 5/8 inch)>5yr, <120hr 0 Count_Weir2 = 0 0.36(diameter = 11/16 inch)Max Depth Row Count_OutletPipe1 = 1 0.42(diameter = 3/4 inch)WQCV 112 Count_OutletPipe2 = 0 0.50(diameter = 13/16 inch)2 Year 144 COUNTA_2 (Standard FSD Setup)= 1 0.58(diameter = 7/8 inch)EURV 194 Hidden Parameters & Calculations 0.67(diameter = 15/16 inch)5 Year 187 MaxPondDepth_Error? FALSE 0.76 (diameter = 1 inch)10 Year 224 Spillway Depth Cd_Broad-Crested Weir 3.00 0.86(diameter = 1-1/16 inches)25 Year 251 0.30 WQ Plate Flow at 100yr depth = 0.11 0.97(diameter = 1-1/8 inches)50 Year 269 CLOG #1= 100% 1.08(diameter = 1-3/16 inches)100 Year 291 1 Z1_Boolean n*Cdw #1 = 0.39 1.20(diameter = 1-1/4 inches)500 Year 389 1 Z2_Boolean n*Cdo #1 = 1.28 1.32(diameter = 1-5/16 inches)Zone3_Pulldown Message 1 Z3_Boolean Overflow Weir #1 Angle = 0.197 1.45(diameter = 1-3/8 inches)1 Opening Message CLOG #2= N/A 1.59(diameter = 1-7/16 inches)Draintime Running n*Cdw #2 = N/A 1.73(diameter = 1-1/2 inches)Outlet Boolean Outlet Rank Total (1 to 4) n*Cdo #2 = N/A 1.88(diameter = 1-9/16 inches)Vertical Orifice 1 0 0 1 Overflow Weir #2 Angle = N/A 2.03(diameter = 1-5/8 inches)Vertical Orifice 2 0 0 Boolean Underdrain Q at 100yr depth = 0.00 2.20(diameter = 1-11/16 inches)Overflow Weir 1 1 1 0 Max Depth VertOrifice1 Q at 100yr depth = 0.00 2.36(diameter = 1-3/4 inches)Overflow Weir 2 0 0 0 500yr Depth VertOrifice2 Q at 100yr depth = 0.00 2.54(diameter = 1-13/16 inches)Outlet Pipe 1 1 1 0 Freeboard 2.72(diameter = 1-7/8 inches)Outlet Pipe 2 0 0 1 Spillway Count_User_Hydrographs 0 2.90(diameter = 1-15/16 inches)0 Spillway Length CountA_3 (EURV & 100yr) = 1 3.09(diameter = 2 inches)FALSE Time Interval CountA_4 (100yr Only) = 1 3.29(use rectangular openings)Button Visibility Boolean COUNTA_5 (FSD Weir Only)= 0 0 WQCV Underdrain COUNTA_6 (EURV Weir Only)= 1 1 WQCV Plate 0 EURV-WQCV Plate Outlet1_Pulldown_Boolean 0 EURV-WQCV VertOriice Outlet2_Pulldown_Boolean 1 Outlet 90% Qpeak Outlet3_Pulldown_Boolean 0 Outlet Undetained 0 Weir Only 90% Qpeak 0 Five Year Ratio Plate 0 Five Year Ratio VertOrifice EURV_draintime_user Spillway Options Offset Overlapping S-A-V-D Chart Axis Default X-axis Left Y-Axis Right Y-Axis minimum bound 0.00 0 0 maximum bound 6.00 70,000 90 S-A-V-D Chart Axis Override X-axis Left Y-Axis Right Y-Axis minimum bound maximum bound MHFD-Detention, Version 4.06 (July 2022) DETENTION BASIN OUTLET STRUCTURE DESIGN 0 5 10 15 20 25 30 0.1 1 10FLOW [cfs]TIME [hr] 500YR IN 500YR OUT 100YR IN 100YR OUT 50YR IN 50YR OUT 25YR IN 25YR OUT 10YR IN 10YR OUT 5YR IN 5YR OUT 2YR IN 2YR OUT EURV IN EURV OUT WQCV IN WQCV OUT 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 0.1 1 10 100PONDING DEPTH [ft]DRAIN TIME [hr] 500YR 100YR 50YR 25YR 10YR 5YR 2YR EURV WQCV 0 10 20 30 40 50 60 70 80 90 0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 0.00 1.00 2.00 3.00 4.00 5.00 6.00 OUTFLOW [cfs]AREA [ft^2], VOLUME [ft^3]PONDING DEPTH [ft] User Area [ft^2] Interpolated Area [ft^2] Summary Area [ft^2] Volume [ft^3] Summary Volume [ft^3] Outflow [cfs] Summary Outflow [cfs] 1719-002_MHFD-Detention_v4-06 Pond E - Full Spectrum Detention, Outlet Structure 11/11/2022, 12:01 PM Project: Basin ID: Depth Increment = ft Watershed Information Top of Micropool -- 0.00 -- -- -- 119 0.003 Selected BMP Type =EDB -- 0.20 -- -- -- 713 0.016 83 0.002 Watershed Area = 12.21 acres -- 0.40 -- -- -- 2,037 0.047 358 0.008 Watershed Length = 1,180 ft -- 0.60 -- -- -- 4,188 0.096 981 0.023 Watershed Length to Centroid = 420 ft -- 0.80 -- -- -- 7,003 0.161 2,100 0.048 Watershed Slope = 0.010 ft/ft -- 1.00 -- -- -- 10,369 0.238 3,837 0.088 Watershed Imperviousness = 67.00% percent -- 1.20 -- -- -- 14,160 0.325 6,290 0.144 Percentage Hydrologic Soil Group A = 0.0% percent -- 1.40 -- -- -- 17,212 0.395 9,427 0.216 Percentage Hydrologic Soil Group B = 0.0% percent -- 1.60 -- -- -- 19,500 0.448 12,904 0.296 Percentage Hydrologic Soil Groups C/D = 100.0% percent -- 1.80 -- -- -- 21,466 0.493 16,980 0.390 Target WQCV Drain Time = 40.0 hours -- 2.00 -- -- -- 23,245 0.534 21,434 0.492 Location for 1-hr Rainfall Depths = Thornton - Civic Center -- 2.20 -- -- -- 25,071 0.576 26,247 0.603 -- 2.40 -- -- -- 26,904 0.618 31,695 0.728 -- 2.60 -- -- -- 28,749 0.660 37,260 0.855 Optional User Overrides -- 2.80 -- -- -- 30,567 0.702 43,192 0.992 Water Quality Capture Volume (WQCV) = 0.267 acre-feet acre-feet -- 3.00 -- -- -- 32,070 0.736 49,455 1.135 Excess Urban Runoff Volume (EURV) = 0.792 acre-feet acre-feet -- 3.20 -- -- -- 33,580 0.771 56,021 1.286 2-yr Runoff Volume (P1 = 0.82 in.) = 0.512 acre-feet 0.82 inches -- 3.40 -- -- -- 35,104 0.806 62,889 1.444 5-yr Runoff Volume (P1 = 1.14 in.) = 0.787 acre-feet 1.14 inches -- 3.60 -- -- -- 36,647 0.841 70,064 1.608 10-yr Runoff Volume (P1 = 1.4 in.) = 1.041 acre-feet 1.40 inches -- 3.80 -- -- -- 38,199 0.877 77,549 1.780 25-yr Runoff Volume (P1 = 1.81 in.) = 1.492 acre-feet 1.81 inches -- 4.00 -- -- -- 40,034 0.919 85,372 1.960 50-yr Runoff Volume (P1 = 2.27 in.) = 1.977 acre-feet 2.27 inches -- 4.20 -- -- -- 41,425 0.951 93,518 2.147 100-yr Runoff Volume (P1 = 2.86 in.) = 2.628 acre-feet 2.86 inches -- 4.40 -- -- -- 42,816 0.983 101,942 2.340 500-yr Runoff Volume (P1 = 4.39 in.) = 4.290 acre-feet 4.39 inches -- 5.40 -- -- -- 49,771 1.143 148,236 3.403 Approximate 2-yr Detention Volume = 0.490 acre-feet -- 6.40 -- -- -- 56,726 1.302 201,484 4.625 Approximate 5-yr Detention Volume = 0.760 acre-feet -- -- -- -- Approximate 10-yr Detention Volume = 0.915 acre-feet -- -- -- -- Approximate 25-yr Detention Volume = 1.103 acre-feet -- -- -- -- Approximate 50-yr Detention Volume = 1.265 acre-feet -- -- -- -- Approximate 100-yr Detention Volume = 1.547 acre-feet -- -- -- -- -- -- -- -- Define Zones and Basin Geometry -- -- -- -- Zone 1 Volume (WQCV) = 0.267 acre-feet -- -- -- -- Zone 2 Volume (EURV - Zone 1) = 0.526 acre-feet -- -- -- -- Zone 3 (100yr + 1 / 2 WQCV - Zones 1 & 2) = 0.888 acre-feet -- -- -- -- Total Detention Basin Volume = 1.680 acre-feet -- -- -- -- Initial Surcharge Volume (ISV) = user ft 3 -- -- -- -- Initial Surcharge Depth (ISD) = user ft -- -- -- -- Total Available Detention Depth (Htotal) =user ft -- -- -- -- Depth of Trickle Channel (HTC) =user ft -- -- -- -- Slope of Trickle Channel (STC) =user ft/ft -- -- -- -- Slopes of Main Basin Sides (Smain) =user H:V -- -- -- -- Basin Length-to-Width Ratio (RL/W) =user -- -- -- -- -- -- -- -- Initial Surcharge Area (AISV) =user ft 2 -- -- -- -- Surcharge Volume Length (LISV) =user ft -- -- -- -- Surcharge Volume Width (WISV) =user ft -- -- -- -- Depth of Basin Floor (HFLOOR) =user ft -- -- -- -- Length of Basin Floor (LFLOOR) =user ft -- -- -- -- Width of Basin Floor (WFLOOR) =user ft -- -- -- -- Area of Basin Floor (AFLOOR) =user ft 2 -- -- -- -- Volume of Basin Floor (VFLOOR) =user ft 3 -- -- -- -- Depth of Main Basin (HMAIN) =user ft -- -- -- -- Length of Main Basin (LMAIN) =user ft -- -- -- -- Width of Main Basin (WMAIN) =user ft -- -- -- -- Area of Main Basin (AMAIN) =user ft 2 -- -- -- -- Volume of Main Basin (VMAIN) =user ft 3 -- -- -- -- Calculated Total Basin Volume (Vtotal) =user acre-feet -- -- -- -- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- -------- DETENTION BASIN STAGE-STORAGE TABLE BUILDER Optional Override Area (ft 2) Length (ft) Optional Override Stage (ft) Stage (ft) Stage - Storage Description Area (ft 2) Width (ft) Gateway Apartments Pond F MHFD-Detention, Version 4.06 (July 2022) Volume (ft 3) Volume (ac-ft) Area (acre) After providing required inputs above including 1-hour rainfall depths, click 'Run CUHP' to generate runoff hydrographs using the embedded Colorado Urban Hydrograph Procedure. Example Zone Configuration (Retention Pond) 1719-002_MHFD-Detention_v4-06 Pond F - Full Spectrum Detention, Basin 12/13/2022, 9:31 AM 1 User Defined Stage-Area Booleans for Message 1 Equal Stage-Area Inputs Watershed L:W 1 CountA Watershed Lc:L Watershed Slope 0 Calc_S_TC Booleans for CUHP 1 CUHP Inputs Complete H_FLOOR 1 CUHP Results Calculated L_FLOOR_OTHER 0.00 ISV 0.00 ISV 0.00 Floor 0.00 Floor 1.53 Zone 1 (WQCV) 1.53 Zone 1 (WQCV) 2.51 Zone 2 (EURV) 2.51 Zone 2 (EURV) 3.69 Z3 (100+1/2WQCV)3.69 Z3 (100+1/2WQCV) DETENTION BASIN STAGE-STORAGE TABLE BUILDER MHFD-Detention, Version 4.06 (July 2022) 0.000 1.160 2.320 3.480 4.640 0.000 0.330 0.660 0.990 1.320 0.00 2.00 4.00 6.00 8.00 Volume (ac-ft)Area (acres)Stage (ft.) Area (acres)Volume (ac-ft) 0 14200 28400 42600 56800 0 5 10 15 20 0.00 2.00 4.00 6.00 8.00 Area (sq.ft.)Length, Width (ft.)Stage (ft) Length (ft)Width (ft)Area (sq.ft.) 1719-002_MHFD-Detention_v4-06 Pond F - Full Spectrum Detention, Basin 12/13/2022, 9:31 AM Project: Basin ID: Estimated Estimated Stage (ft) Volume (ac-ft) Outlet Type Zone 1 (WQCV) 1.53 0.267 Orifice Plate Zone 2 (EURV) 2.51 0.526 Orifice Plate Z3 (100+1/2WQCV) 3.69 0.888 Weir&Pipe (Restrict) Total (all zones) 1.680 User Input: Orifice at Underdrain Outlet (typically used to drain WQCV in a Filtration BMP)Calculated Parameters for Underdrain Underdrain Orifice Invert Depth = ft (distance below the filtration media surface) Underdrain Orifice Area =ft2 Underdrain Orifice Diameter = inches Underdrain Orifice Centroid = feet User Input: Orifice Plate with one or more orifices or Elliptical Slot Weir (typically used to drain WQCV and/or EURV in a sedimentation BMP)Calculated Parameters for Plate Centroid of Lowest Orifice = 0.00 ft (relative to basin bottom at Stage = 0 ft) WQ Orifice Area per Row =1.250E-02 ft2 Depth at top of Zone using Orifice Plate = 2.50 ft (relative to basin bottom at Stage = 0 ft) Elliptical Half-Width = N/A feet Orifice Plate: Orifice Vertical Spacing = 10.00 inches Elliptical Slot Centroid = N/A feet Orifice Plate: Orifice Area per Row = 1.80 sq. inches (diameter = 1-1/2 inches)Elliptical Slot Area = N/A ft2 User Input: Stage and Total Area of Each Orifice Row (numbered from lowest to highest) Row 1 (required) Row 2 (optional) Row 3 (optional) Row 4 (optional) Row 5 (optional) Row 6 (optional) Row 7 (optional) Row 8 (optional) Stage of Orifice Centroid (ft) 0.00 0.80 1.60 2.40 Orifice Area (sq. inches) 1.80 1.80 1.80 1.80 Row 9 (optional) Row 10 (optional) Row 11 (optional) Row 12 (optional) Row 13 (optional) Row 14 (optional) Row 15 (optional) Row 16 (optional) Stage of Orifice Centroid (ft) Orifice Area (sq. inches) User Input: Vertical Orifice (Circular or Rectangular)Calculated Parameters for Vertical Orifice Not Selected Not Selected Not Selected Not Selected Invert of Vertical Orifice = N/A N/A ft (relative to basin bottom at Stage = 0 ft) Vertical Orifice Area =N/A N/A ft2 Depth at top of Zone using Vertical Orifice = N/A N/A ft (relative to basin bottom at Stage = 0 ft) Vertical Orifice Centroid = N/A N/A feet Vertical Orifice Diameter = N/A N/A inches User Input: Overflow Weir (Dropbox with Flat or Sloped Grate and Outlet Pipe OR Rectangular/Trapezoidal Weir and No Outlet Pipe) Calculated Parameters for Overflow Weir grate Zone 3 Weir Not Selected Zone 3 Weir Not Selected Overflow Weir Front Edge Height, Ho = 2.70 N/A ft (relative to basin bottom at Stage = 0 ft)Height of Grate Upper Edge, Ht =3.70 N/A feet Overflow Weir Front Edge Length = 5.00 N/A feet Overflow Weir Slope Length = 5.10 N/A feet Overflow Weir Grate Slope = 5.00 N/A H:V Grate Open Area / 100-yr Orifice Area = 10.04 N/A Horiz. Length of Weir Sides = 5.00 N/A feet Overflow Grate Open Area w/o Debris = 17.74 N/A ft2 Overflow Grate Type = Type C Grate N/A Overflow Grate Open Area w/ Debris = 17.74 N/A ft2 Debris Clogging % = 0% N/A % User Input: Outlet Pipe w/ Flow Restriction Plate (Circular Orifice, Restrictor Plate, or Rectangular Orifice)Calculated Parameters for Outlet Pipe w/ Flow Restriction Plate Zone 3 Restrictor Not Selected Zone 3 Restrictor Not Selected Depth to Invert of Outlet Pipe = 0.00 N/A ft (distance below basin bottom at Stage = 0 ft)Outlet Orifice Area = 1.77 N/A ft2 Outlet Pipe Diameter = 18.00 N/A inches Outlet Orifice Centroid = 0.75 N/A feet Restrictor Plate Height Above Pipe Invert = 18.00 inches Half-Central Angle of Restrictor Plate on Pipe =3.14 N/A radians User Input: Emergency Spillway (Rectangular or Trapezoidal)Calculated Parameters for Spillway Spillway Invert Stage= 4.20 ft (relative to basin bottom at Stage = 0 ft) Spillway Design Flow Depth= 0.51 feet Spillway Crest Length = 32.00 feet Stage at Top of Freeboard = 4.71 feet Spillway End Slopes = 29.00 H:V Basin Area at Top of Freeboard = 1.03 acres Freeboard above Max Water Surface = feet Basin Volume at Top of Freeboard = 2.65 acre-ft Max Ponding Depth of Target Storage Volume =3.69 feet Discharge at Top of Freeboard = 16.93 cfs Routed Hydrograph Results Design Storm Return Period =WQCV EURV 2 Year 5 Year 10 Year 25 Year 50 Year 100 Year 500 Year One-Hour Rainfall Depth (in) =N/A N/A 0.82 1.14 1.40 1.81 2.27 2.86 4.39 CUHP Runoff Volume (acre-ft) =0.267 0.792 0.512 0.787 1.041 1.492 1.977 2.628 4.290 Inflow Hydrograph Volume (acre-ft) =N/A N/A 0.512 0.787 1.041 1.492 1.977 2.628 4.290 CUHP Predevelopment Peak Q (cfs) =N/A N/A 0.1 1.4 3.4 8.4 12.8 19.1 33.8 OPTIONAL Override Predevelopment Peak Q (cfs) =N/A N/A Predevelopment Unit Peak Flow, q (cfs/acre) =N/A N/A 0.01 0.12 0.28 0.69 1.05 1.56 2.77 Peak Inflow Q (cfs) =N/A N/A 8.1 12.6 16.5 24.4 32.2 43.1 69.2 Peak Outflow Q (cfs) =0.1 0.2 0.2 0.2 0.6 3.8 8.8 14.6 17.2 Ratio Peak Outflow to Predevelopment Q =N/A N/A N/A 0.2 0.2 0.5 0.7 0.8 0.5 Structure Controlling Flow =Plate Plate Plate Plate Overflow Weir 1 Overflow Weir 1 Overflow Weir 1 Outlet Plate 1 Outlet Plate 1 Max Velocity through Grate 1 (fps) =N/A N/A N/A N/A 0.0 0.2 0.5 0.8 0.9 Max Velocity through Grate 2 (fps) =N/A N/A N/A N/A N/A N/A N/A N/A N/A Time to Drain 97% of Inflow Volume (hours) =37 67 54 67 75 73 71 68 62 Time to Drain 99% of Inflow Volume (hours) =39 71 57 72 81 81 80 78 75 Maximum Ponding Depth (ft) =1.53 2.51 1.97 2.43 2.79 3.10 3.35 3.69 4.82 Area at Maximum Ponding Depth (acres) =0.43 0.64 0.53 0.62 0.70 0.75 0.80 0.86 1.05 Maximum Volume Stored (acre-ft) =0.270 0.797 0.481 0.746 0.978 1.202 1.404 1.676 2.767 The user can override the default CUHP hydrographs and runoff volumes by entering new values in the Inflow Hydrographs table (Columns W through AF). DETENTION BASIN OUTLET STRUCTURE DESIGN MHFD-Detention, Version 4.06 (July 2022) Gateway Apartments Pond F Example Zone Configuration (Retention Pond) 1719-002_MHFD-Detention_v4-06 Pond F - Full Spectrum Detention, Outlet Structure 12/13/2022, 9:32 AM COUNTA for Basin Tab = 1 Ao Dia WQ Plate Type Vert Orifice 1Vert Orifice 2 Count_Underdrain = 0 0.11(diameter = 3/8 inch)2 1 1 Count_WQPlate = 1 0.14(diameter = 7/16 inch) Count_VertOrifice1 = 0 0.18(diameter = 1/2 inch)Outlet Plate 1 Outlet Plate 2 Drain Time Message Boolean Count_VertOrifice2 = 0 0.24(diameter = 9/16 inch)4 1 5yr, <72hr 0 Count_Weir1 = 1 0.29(diameter = 5/8 inch)>5yr, <120hr 0 Count_Weir2 = 0 0.36(diameter = 11/16 inch)Max Depth Row Count_OutletPipe1 = 1 0.42(diameter = 3/4 inch)WQCV 154 Count_OutletPipe2 = 0 0.50(diameter = 13/16 inch)2 Year 198 COUNTA_2 (Standard FSD Setup)= 1 0.58(diameter = 7/8 inch)EURV 252 Hidden Parameters & Calculations 0.67(diameter = 15/16 inch)5 Year 244 MaxPondDepth_Error? FALSE 0.76 (diameter = 1 inch)10 Year 280 Spillway Depth Cd_Broad-Crested Weir 3.00 0.86(diameter = 1-1/16 inches)25 Year 311 0.51 WQ Plate Flow at 100yr depth = 0.37 0.97(diameter = 1-1/8 inches)50 Year 336 CLOG #1= 100% 1.08(diameter = 1-3/16 inches)100 Year 370 1 Z1_Boolean n*Cdw #1 = 0.39 1.20(diameter = 1-1/4 inches)500 Year 483 1 Z2_Boolean n*Cdo #1 = 1.28 1.32(diameter = 1-5/16 inches)Zone3_Pulldown Message 1 Z3_Boolean Overflow Weir #1 Angle = 0.197 1.45(diameter = 1-3/8 inches)1 Opening Message CLOG #2= N/A 1.59(diameter = 1-7/16 inches)Draintime Running n*Cdw #2 = N/A 1.73(diameter = 1-1/2 inches)Outlet Boolean Outlet Rank Total (1 to 4) n*Cdo #2 = N/A 1.88(diameter = 1-9/16 inches)Vertical Orifice 1 0 0 1 Overflow Weir #2 Angle = N/A 2.03(diameter = 1-5/8 inches)Vertical Orifice 2 0 0 Boolean Underdrain Q at 100yr depth = 0.00 2.20(diameter = 1-11/16 inches)Overflow Weir 1 1 1 0 Max Depth VertOrifice1 Q at 100yr depth = 0.00 2.36(diameter = 1-3/4 inches)Overflow Weir 2 0 0 0 500yr Depth VertOrifice2 Q at 100yr depth = 0.00 2.54(diameter = 1-13/16 inches)Outlet Pipe 1 1 1 0 Freeboard 2.72(diameter = 1-7/8 inches)Outlet Pipe 2 0 0 0 Spillway Count_User_Hydrographs 0 2.90(diameter = 1-15/16 inches)0 Spillway Length CountA_3 (EURV & 100yr) = 1 3.09(diameter = 2 inches)FALSE Time Interval CountA_4 (100yr Only) = 1 3.29(use rectangular openings)Button Visibility Boolean COUNTA_5 (FSD Weir Only)= 0 0 WQCV Underdrain COUNTA_6 (EURV Weir Only)= 1 1 WQCV Plate 0 EURV-WQCV Plate Outlet1_Pulldown_Boolean 0 EURV-WQCV VertOriice Outlet2_Pulldown_Boolean 1 Outlet 90% Qpeak Outlet3_Pulldown_Boolean 0 Outlet Undetained 0 Weir Only 90% Qpeak 0 Five Year Ratio Plate 0 Five Year Ratio VertOrifice EURV_draintime_user Spillway Options Offset Overlapping S-A-V-D Chart Axis Default X-axis Left Y-Axis Right Y-Axis minimum bound 0.00 0 0 maximum bound 6.00 130,000 20 S-A-V-D Chart Axis Override X-axis Left Y-Axis Right Y-Axis minimum bound maximum bound MHFD-Detention, Version 4.06 (July 2022) DETENTION BASIN OUTLET STRUCTURE DESIGN 0 10 20 30 40 50 60 70 80 0.1 1 10FLOW [cfs]TIME [hr] 500YR IN 500YR OUT 100YR IN 100YR OUT 50YR IN 50YR OUT 25YR IN 25YR OUT 10YR IN 10YR OUT 5YR IN 5YR OUT 2YR IN 2YR OUT EURV IN EURV OUT WQCV IN WQCV OUT 0 1 2 3 4 5 6 0.1 1 10 100PONDING DEPTH [ft]DRAIN TIME [hr] 500YR 100YR 50YR 25YR 10YR 5YR 2YR EURV WQCV 0 2 4 6 8 10 12 14 16 18 20 0 20,000 40,000 60,000 80,000 100,000 120,000 0.00 1.00 2.00 3.00 4.00 5.00 6.00 OUTFLOW [cfs]AREA [ft^2], VOLUME [ft^3]PONDING DEPTH [ft] User Area [ft^2] Interpolated Area [ft^2] Summary Area [ft^2] Volume [ft^3] Summary Volume [ft^3] Outflow [cfs] Summary Outflow [cfs] 1719-002_MHFD-Detention_v4-06 Pond F - Full Spectrum Detention, Outlet Structure 12/13/2022, 9:32 AM NORTHERNENGINEERING.COM | 970.221.4158 FINAL DRAINAGE REPORT: GATEWAY APARTMENTS FORT COLLINS | GREELEY APPENDIX APPENDIX B HYDRAULIC CALCULATIONS Preliminary Drainage Report This section intentionally left blank. Hydraulic calculations will be completed during final design. NORTHERNENGINEERING.COM | 970.221.4158 FINAL DRAINAGE REPORT: GATEWAY APARTMENTS FORT COLLINS | GREELEY APPENDIX APPENDIX C WATER QUALITY/LID COMPUTATIONS X X XXX XXXXXXXXXXXXXXXXOHE OHU XXXX XT T T OHU OHU OHU OHU OHU 8" SS 10" SS 27" S S E E E W W W W W W W / / / / / / / / T W W W W W S W SSS H2O ELEC VAULT ELEC OHU OHU OHU OHU X / / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / / X X XCONTROL IRR CONTROL IRR H2O H2O ELEC AC W W W B L BLBLBLBLBLBLBL BLBLBLBL BL BL BLBL BLSS SDSDSDSDS H2O H2O HY DT S S GGXXXX XE GOHU OHU OHU OHU OHU OHU OHU OHU OHU S S 12" W 12" W 12" W V.P. V.P.H2O YIELDYIELD30" SS30" SS30" SS30" SS30" SS27" SS 27" SS 27" SS 2 7 " SS12" W12" W12" W12" W12" W12" W12" W 12" W 12" W 12" W 12" W SD12" W EEEEEEEEEEE EEEEEEEEEEEEEEVAULTVAU LT VAU L T EEEEEVAULTEEEEEEEEEEEEEEEEEEEEEEEEEVAULT SD SDSDNYLOPLASTDO NOT POLLUTEDRAINS TOWATERWAYS DO NOT POLLUTE DRAINS TO WATERWAYS NYLOPLAST DUCTILE IRON NYLOPLAST DO NOT POLLUTE DRAINS TO WATERWAYS NYLOPLAST DO NOT POLLUTE DRAINS TO WATERWAYS NYLOPLAST DO NOT POLLUTEDRAINS TOWATERWAYSDO NOT POLLUTE DRAINS TO WATERWAYSNYLOPLAST DUCTILE IRON NYLOPLAST DO NOT POLLUTE DRAINS TO WATERWAYS NYLOPLAST DO NOT POLLUTE DRAINS TO WATERWAYS NYLOPLASTDO NOT POLLUTEDRAINS TOWATERWAYS DO NOT POLLUTE DRAINS TO WATERWAYS NYLOPLAST DUCTILE IRON NYLOPLAST DO NOT POLLUTEDRAINS TOWATERWAYS DO NOT POLLUTE DRAINS TO WATERWAYSNYLOPLAST DUCTILE IRON NYLOPLAST DO NOT POLLUTEDRAINS TOWATERWAYSDO NOT POLLUTE DRAINS TO WATERWAYS NYLOPLAST DUCTILE IRON NYLOPLASTDO NOT POLLUTEDRAINS TOWATERWAYSDO NOT POLLUTE DRAINS TO WATERWAYSNYLOPLAST DUCTILE IRON NYLOPLASTDO NOT POLLUTEDRAINS TOWATERWAYS DO NOT POLLUTE DRAINS TO WATERWAYSNYLOPLAST DUCTILE IRON NYLOPLASTDO NOT POLLUTEDRAINS TOWATERWAYS DO NOT POLLUTE DRAINS TO WATERWAYS NYLOPLAST DUCTILE IRONNYLOPLASTDO NOT POLLUTEDRAINS TOWATERWAYS DO NOT POLLUTE DRAINS TO WATERWAYS NYLOPLAST DUCTILE IRON NYLOPLASTDO NOT POLLUTEDRAINS TOWATERWAYSDO NOT POLLUTE DRAINS TO WATERWAYS NYLOPLAST DUCTILE IRON NYLOPLAST DO NOT POLLUTEDRAINS TOWATERWAYSDO NOT POLLUTE DRAINS TO WATERWAYSNYLOPLAST DUCTILE IRON XXXXXXX XXXE1.1 F1.5 F5 E1.3 E1.4 F1.1 E2 F1.4 F1.8 F3 F1.3 F2 F1.2 F1.6 F1.7 E1.2 F4 STORMTECH CHAMBERS 2 STORMTECH CHAMBERS 1 RAIN GARDEN 1 PLANNED RAIN GARDEN F5 SEE GATEWAY AT PROSPECT PLANS f2 f1.7 f3f1.5 f1.6 f1.8 f1.4 f1.2 f1.3 f1.1 f4f5 e1.2 e1.3 e1.4 e2 e1.1 DRAWN BY: SCALE: ISSUED: GATEWAY 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 A. Boese 1in=150ft 01/04/23 PROPOSED STORM SEWER PROPOSED CURB & GUTTER PROPERTY BOUNDARY PROPOSED INLET ADESIGN POINT DRAINAGE BASIN LABEL DRAINAGE BASIN BOUNDARY A LEGEND: 150 150 150 RAIN GARDEN LIMITS STORMTECH CHAMBERS FOR DRAINAGE REVIEW ONLY NOT FOR CONSTRUCTION On-Site LID Treatment Project Summary Total Impervious Area 454,802 sf Target Treatment Percentage 75% Minimum Area to be Treated by LID measures 341,102 sf Rain Garden Area Rain Garden 1 Area Run-on area for Rain Garden 1 96,976 sf Total Rain Garden Treatment Area 2,251 sf Overall Run-on Ratio for Rain Garden 1 (50:1 Max) 43 :1 Total Treatment Area 351,030 sf Percent Total Project Area Treated 77.2% Project Number:Project: Project Location: Calculations By:Date: Sq. Ft. Acres LID 1 224,011 5.14 82%Stormtech 1 Stormtech 6,111 183,689 LID 2 107,749 2.47 80%Stormtech 2 Stormtech 2,826 86,199 LID 3 52,541 1.21 40%Rain Garden F5 Rain Garden 756 21,016 LID 4 96,976 2.23 62%Rain Garden 1 Rain Garden 1,885 60,125 F1.4 57,429 1.32 75%n/a n/a 0 43,072 F1.8 74,910 1.72 14%n/a n/a 0 10,487 F3 16,363 0.38 90%n/a n/a 0 14,727 E1.1 21,793 0.50 73%n/a n/a 0 15,909 E2 34,952 0.80 50%n/a n/a 0 17,476 E1.4 30,022 0.69 7%n/a n/a 0 2,102 Total 716,746 16.45 454,802 Sq. Ft. Acres Stormtech 1 224,011 5.14 82% 183,689 F1.1 to F1.3, F4 Stormtech 5,093 6,111 Stormtech 2 107,749 2.47 80% 86,199 F1.5 to F1.7, F2 Stormtech 2,355 2,826 Rain Garden F5 52,541 1.21 40% 21,016 F5 Rain Garden 630 756 Rain Garden 1 96,976 2.23 62% 60,125 E1.2 to E1.3 Rain Garden 1,571 1,885 Total 481,277 11.05 351,030 11,578 Sq. Ft. Acres Pond E 183,743 4.22 52% 95,612 E1.1 to E1.4, E2 Full Spectrum 3,223 3,868 Pond F 532,003 12.21 68% 359,190 F1.1 to F1.8, F2 to F5 Full Spectrum 11,631 13,957 Total 715,746 16.43 454,802 17,824 716,746 ft2 454,802 ft2 341,102 ft2 351,030 ft2 77.18% 454,802 ft2 100.00% 100.00% Water Quality Treatment via Traditional Water Quality LID Summary AreaBasin ID WQ Treatment TypePercent Impervious LID ID Gateway Apartments 11/11/2022 1719-002 Fort Collins, Colorado A. Boese Total Impervious Area (ft2) Required Volume (ft3) LID Summary per Basin Tributary Area Weighted % Impervious Impervious Area (ft2) Vol. w/20% Increase per Fort Collins Subbasin ID Treatment TypeWQ Treatment Volume per UD-BMP or FAA (ft3) Water Quality Treatment via LID Percent Impervious Area Treated by Traditional WQ or LID Total Impervious Area Treated by LID 75% Required Minimum Area to be Treated by LID Total Area of Current Development Total Impervious Area Vol. w/20% Increase per Fort Collins Manual (ft3) 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- Detention (ft3) Percent Impervious Treated by LID Subbasin IDImpervious Area (ft2) Project TitleDate:Project NumberCalcs By:CityBasins0.8WQCV = Watershed inches of Runoff (inches)82%a = Runoff Volume Reduction (constant)i = Total imperviousness Ratio (i = Iwq/100)0.273 in5.14 ac0.1169 ac-ft 5093 cu. ft.0.1403 ac-ft 6111 cu. ft.V = Water Quality Design Volume (ac-ft)WQCV = Water Quality Capture Volume (inches)A = Watershed Area (acres)V = V (120%) = A =Gateway ApartmentsNovember 11, 20221719-002S. ThomasFort CollinsStormtech Chambers 1Drain Timea = i = WQCV = Figure EDB-2 - Water Quality Capture Volume (WQCV), 80th Percentile Runoff Event0.23100.050.10.150.20.250.30.350.40.450.500.10.20.30.40.50.60.70.80.91WQCV (watershed inches)Total Imperviousness Ratio (i = Iwq/100)Water Quality Capture Volume6 hr12 hr24 hr40 hr()iii78.019.10.91aWQCV23+-=()iii78.019.10.91aWQCV23+-=AV*12WQCV=12 hr Pond No :F1.2WQ0.865.60 min1785ft35.14 acres0.04ac-ftMax Release Rate =2.15 cfsTime (min)Ft Collins WQ Intensity (in/hr)Inflow Volume(ft3)Outflow Adjustment FactorQWQ(cfs)Outflow Volume(ft3)Storage Volume (ft3)5 1.425 1890 1.00 2.15 645 124510 1.105 2931 1.00 2.15 1290 164115 0.935 3720 1.00 2.15 1935 178520 0.805 4270 1.00 2.15 2580 169025 0.715 4741 1.00 2.15 3225 151630 0.650 5172 1.00 2.15 3870 130235 0.585 5430 1.00 2.15 4515 91540 0.535 5676 1.00 2.15 5160 51645 0.495 5908 1.00 2.15 5805 10350 0.460 6100 1.00 2.15 6450 -35055 0.435 6345 1.00 2.15 7095 -75060 0.410 6525 1.00 2.15 7740 -121565 0.385 6637 1.00 2.15 8385 -174870 0.365 6776 1.00 2.15 9030 -225475 0.345 6863 1.00 2.15 9675 -281280 0.330 7002 1.00 2.15 10320 -331885 0.315 7101 1.00 2.15 10965 -386490 0.305 7280 1.00 2.15 11610 -433095 0.290 7307 1.00 2.15 12255 -4948100 0.280 7426 1.00 2.15 12900 -5474105 0.270 7519 1.00 2.15 13545 -6026110 0.260 7585 1.00 2.15 14190 -6605115 0.255 7778 1.00 2.15 14835 -7057120 0.245 7798 1.00 2.15 15480 -7682*Note: Using the method described in FCSCM Chapter 6 Section 2.3A =Tc =Project Location :Design PointC =Design StormDETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDFInput VariablesResultsRequired Detention VolumeFort Collins, Colorado1719-002Gateway ApartmentsProject Number :Project Name :Stormtech Chambers 1Page 3 of 41719-002_Stormtech Chambers 1 Vault ID Total Required WQ Volume (cf) Flow, WQ (cfs) Chamber Type Chamber Release Ratea (cfs) Chamber Volumeb (cf) Installed Chamber w/ Aggregatec (cf) Minimum No. of Chambersd Total Release Ratee (cfs) Required Storage Volume by FAA Method (cf) Minimum No. of Chambersf Provided Number of Chambers Provided Release Rate (cfs) Storage Provided within the Chambersg (cf) Total Installed System Volumeh (cf) Chambers 1 6111 12.21 SC-740 0.024 45.90 67.65 91 2.15 1785 39 91 2.15 4177 6156 a. Release rate per chamber, limited by flow through geotextile with accumulated sediment. b. Volume within chamber only, not accounting for void spaces in surrounding aggregate. c. Volume includes chamber and void spaces (30%) in surrounding aggregate, per chamber unit. d. Number of chambers required to provide full WQCV within total installed system, including aggregate. e. Release rate per chamber times number of chambers. f. Number of chambers required to provide required FAA storage volume stored within the chamber only (no aggregate storage). g. Volume provided in chambers only (no aggregate storage). This number must meet or exceed the required FAA storage volume. h. System volume includes total number of chambers, plus surrounding aggregate. This number must meet or exceed the required WQCV. Chamber Configuration Summary P:\1719-002\Drainage\WatQual\1719-002_Stormtech Chambers 1 Chamber DimensionsSC-160 SC-310 SC-740 MC-3500 MC-4500Width (in)34.0 34.0 51.0 77.0 100.0Length (in)85.4 85.4 85.4 90.0 52.0Height (in)16.0 16.0 30.0 45.0 60.0Floor Area (sf)20.2 20.2 30.2 48.1 36.1Chamber Volume (cf)6.9 14.7 45.9 109.9 106.5Chamber/Aggregate Volume (cf)23.7 25.7 67.7 158.7 148.6Flow Rate* 0.35 gpm/sf1 cf =7.48052gal1 gallon =0.133681cf1 GPM = 0.002228cfs*Flow rate based on 1/2 of Nov 07 QMAX in Figure 17 of UNH Testing ReportSC-160SC-310 SC-740 MC-3500 MC-4500Flow Rate/chamber (cfs) 0.015724 0.015724 0.023586 0.037528 0.028159end caps have a volume of 108.7 cu. ft.StormTech Chamber DataChamber Flow RateChamber Flow Rate Conversion (gpm/sf to cfs)end caps have a volume of 45.1 cu. ft.P:\1719-002\Drainage\WatQual\1719-002_Stormtech Chambers 1 Project TitleDate:Project NumberCalcs By:CityBasins0.8WQCV = Watershed inches of Runoff (inches)80%a = Runoff Volume Reduction (constant)i = Total imperviousness Ratio (i = Iwq/100)0.263 in2.47 ac0.0541 ac-ft 2355 cu. ft.0.0649 ac-ft 2826 cu. ft.V = Water Quality Design Volume (ac-ft)WQCV = Water Quality Capture Volume (inches)A = Watershed Area (acres)V = V (120%) = A =Gateway ApartmentsNovember 11, 20221719-002S. ThomasFort CollinsStormtech Chambers 2Drain Timea = i = WQCV = Figure EDB-2 - Water Quality Capture Volume (WQCV), 80th Percentile Runoff Event0.23100.050.10.150.20.250.30.350.40.450.500.10.20.30.40.50.60.70.80.91WQCV (watershed inches)Total Imperviousness Ratio (i = Iwq/100)Water Quality Capture Volume6 hr12 hr24 hr40 hr()iii78.019.10.91aWQCV23+-=()iii78.019.10.91aWQCV23+-=AV*12WQCV=12 hr Pond No :F1.7WQ0.855.10 min373ft32.47 acres0.01ac-ftMax Release Rate =1.75 cfsTime (min)Ft Collins WQ Intensity (in/hr)Inflow Volume(ft3)Outflow Adjustment FactorQWQ(cfs)Outflow Volume(ft3)Storage Volume (ft3)5 1.425 898 1.00 1.75 525 37310 1.105 1392 1.00 1.75 1050 34215 0.935 1767 1.00 1.75 1575 19220 0.805 2028 1.00 1.75 2100 -7225 0.715 2252 1.00 1.75 2625 -37330 0.650 2456 1.00 1.75 3150 -69435 0.585 2579 1.00 1.75 3675 -109640 0.535 2696 1.00 1.75 4200 -150445 0.495 2806 1.00 1.75 4725 -191950 0.460 2897 1.00 1.75 5250 -235355 0.435 3014 1.00 1.75 5775 -276160 0.410 3099 1.00 1.75 6300 -320165 0.385 3152 1.00 1.75 6825 -367370 0.365 3219 1.00 1.75 7350 -413175 0.345 3259 1.00 1.75 7875 -461680 0.330 3326 1.00 1.75 8400 -507485 0.315 3373 1.00 1.75 8925 -555290 0.305 3458 1.00 1.75 9450 -599295 0.290 3470 1.00 1.75 9975 -6505100 0.280 3527 1.00 1.75 10500 -6973105 0.270 3571 1.00 1.75 11025 -7454110 0.260 3603 1.00 1.75 11550 -7947115 0.255 3694 1.00 1.75 12075 -8381120 0.245 3704 1.00 1.75 12600 -8896*Note: Using the method described in FCSCM Chapter 6 Section 2.3DETENTION POND CALCULATION; MODIFIED FAA METHOD w/ Ft Collins IDFInput VariablesResultsRequired Detention VolumeFort Collins, Colorado1719-002Gateway ApartmentsProject Number :Project Name :Stormtech Chambers 2A =Tc =Project Location :Design PointC =Design StormPage 3 of 41719-002_Stormtech Chambers 2 Vault ID Total Required WQ Volume (cf) Flow, WQ (cfs) Chamber Type Chamber Release Ratea (cfs) Chamber Volumeb (cf) Installed Chamber w/ Aggregatec (cf) Minimum No. of Chambersd Total Release Ratee (cfs) Required Storage Volume by FAA Method (cf) Minimum No. of Chambersf Provided Number of Chambers Provided Release Rate (cfs) Storage Provided within the Chambersg (cf) Total Installed System Volumeh (cf) Chambers 2 2826 5.99 SC-310 0.016 14.70 25.65 111 1.75 373 26 111 1.75 1632 2847 a. Release rate per chamber, limited by flow through geotextile with accumulated sediment. b. Volume within chamber only, not accounting for void spaces in surrounding aggregate. c. Volume includes chamber and void spaces (30%) in surrounding aggregate, per chamber unit. d. Number of chambers required to provide full WQCV within total installed system, including aggregate. e. Release rate per chamber times number of chambers. f. Number of chambers required to provide required FAA storage volume stored within the chamber only (no aggregate storage). g. Volume provided in chambers only (no aggregate storage). This number must meet or exceed the required FAA storage volume. h. System volume includes total number of chambers, plus surrounding aggregate. This number must meet or exceed the required WQCV. Chamber Configuration Summary P:\1719-002\Drainage\WatQual\1719-002_Stormtech Chambers 2 Chamber DimensionsSC-160 SC-310 SC-740 MC-3500 MC-4500Width (in)34.0 34.0 51.0 77.0 100.0Length (in)85.4 85.4 85.4 90.0 52.0Height (in)16.0 16.0 30.0 45.0 60.0Floor Area (sf)20.2 20.2 30.2 48.1 36.1Chamber Volume (cf)6.9 14.7 45.9 109.9 106.5Chamber/Aggregate Volume (cf)23.7 25.7 67.7 158.7 148.6Flow Rate* 0.35 gpm/sf1 cf =7.48052gal1 gallon =0.133681cf1 GPM = 0.002228cfs*Flow rate based on 1/2 of Nov 07 QMAX in Figure 17 of UNH Testing ReportSC-160SC-310 SC-740 MC-3500 MC-4500Flow Rate/chamber (cfs) 0.015724 0.015724 0.023586 0.037528 0.028159end caps have a volume of 108.7 cu. ft.StormTech Chamber DataChamber Flow RateChamber Flow Rate Conversion (gpm/sf to cfs)end caps have a volume of 45.1 cu. ft.P:\1719-002\Drainage\WatQual\1719-002_Stormtech Chambers 2 Sheet 1 of 2 Designer: Company: Date: Project: Location: 1. Basin Storage Volume A) Effective Imperviousness of Tributary Area, Ia Ia =62.0 % (100% if all paved and roofed areas upstream of rain garden) B) Tributary Area's Imperviousness Ratio (i = Ia/100)i = 0.620 C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.19 watershed inches (WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i) D) Contributing Watershed Area (including rain garden area) Area = 96,976 sq ft E) Water Quality Capture Volume (WQCV) Design Volume VWQCV =cu ft Vol = (WQCV / 12) * Area F) For Watersheds Outside of the Denver Region, Depth of d6 = in Average Runoff Producing Storm G) For Watersheds Outside of the Denver Region, VWQCV OTHER =cu ft Water Quality Capture Volume (WQCV) Design Volume H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER =1,885 cu ft (Only if a different WQCV Design Volume is desired) 2. Basin Geometry A) WQCV Depth (12-inch maximum)DWQCV =12 in B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 4.00 ft / ft (Use "0" if rain garden has vertical walls) C) Mimimum Flat Surface Area AMin =1203 sq ft D) Actual Flat Surface Area AActual =1532 sq ft E) Area at Design Depth (Top Surface Area)ATop =2251 sq ft F) Rain Garden Total Volume VT=1,892 cu ft (VT= ((ATop + AActual) / 2) * Depth) 3. Growing Media 4. Underdrain System A) Are underdrains provided?1 B) Underdrain system orifice diameter for 12 hour drain time i) Distance From Lowest Elevation of the Storage y =ft Volume to the Center of the Orifice ii) Volume to Drain in 12 Hours Vol12 =1,885 cu ft iii) Orifice Diameter, 3/8" Minimum DO =1/2 in Design Procedure Form: Rain Garden (RG) Stephanie Thomas Northern Engineering November 11, 2022 Gateway Apartments Basin E1.2 to Basin E1.3 UD-BMP (Version 3.07, March 2018) Choose One Choose One 18" Rain Garden Growing Media Other (Explain): YES NO 1719-001_ Rain Garden 1 UD-BMP_v3.07, RG 11/11/2022, 1:06 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? 6. Inlet / Outlet Control A) Inlet Control 7. Vegetation 8. Irrigation A) Will the rain garden be irrigated? Notes: Design Procedure Form: Rain Garden (RG) Stephanie Thomas Northern Engineering November 11, 2022 Gateway Apartments Basin E1.2 to Basin E1.3 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 1719-001_ Rain Garden 1 UD-BMP_v3.07, RG 11/11/2022, 1:06 PM Pond Stage-Storage Curve Rain Garden 1 Project: 1719-002 By: ALB Date: 11/11/22 Stage (FT) Contour Area (SF) Volume (CU.FT.) Volume (AC-FT) 4,901.50 1,555.66 0 0.00 4,901.60 1,619.56 158.75 0.00 4,901.80 1,747.64 495.39 0.01 4,902.00 1,880.95 858.17 0.02 4,902.20 2,019.51 1248.13 0.03 4,902.40 2,163.31 1666.33 0.04 4,902.50 2,251.14 1887.04 0.04 LID Volume NORTHERNENGINEERING.COM | 970.221.4158 FINAL DRAINAGE REPORT: GATEWAY APARTMENTS FORT COLLINS | GREELEY APPENDIX APPENDIX D EROSION CONTROL REPORT NORTHERNENGINEERING.COM | 970.221.4158 FINAL DRAINAGE REPORT: GATEWAY 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 FINAL DRAINAGE REPORT: GATEWAY 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, ColoradoNatural Resources Conservation Service December 12, 2022 Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/ portal/nrcs/main/soils/health/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/? cid=nrcs142p2_053951). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey information. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require 2 alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. 3 Contents Preface....................................................................................................................2 How Soil Surveys Are Made..................................................................................5 Soil Map..................................................................................................................8 Soil Map (Gateway Apartments)...........................................................................9 Legend................................................................................................................10 Map Unit Legend (Gateway Apartments)...........................................................11 Map Unit Descriptions (Gateway Apartments)....................................................11 Larimer County Area, Colorado......................................................................13 76—Nunn clay loam, wet, 1 to 3 percent slopes.........................................13 98—Satanta Variant clay loam, 0 to 3 percent slopes.................................14 References............................................................................................................16 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 (Gateway Apartments)449069044907604490830449090044909704491040449069044907604490830449090044909704491040498980 499050 499120 499190 499260 499330 499400 499470 499540 499610 498980 499050 499120 499190 499260 499330 499400 499470 499540 499610 40° 34' 13'' N 105° 0' 43'' W40° 34' 13'' N105° 0' 16'' W40° 33' 59'' N 105° 0' 43'' W40° 33' 59'' N 105° 0' 16'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 100 200 400 600 Feet 0 40 80 160 240 Meters Map Scale: 1:2,960 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 (Gateway Apartments) Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 76 Nunn clay loam, wet, 1 to 3 percent slopes 1.1 6.1% 98 Satanta Variant clay loam, 0 to 3 percent slopes 16.4 93.9% Totals for Area of Interest 17.5 100.0% Map Unit Descriptions (Gateway Apartments) 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 Custom Soil Resource Report 11 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 76—Nunn clay loam, wet, 1 to 3 percent slopes Map Unit Setting National map unit symbol: jpxq Elevation: 4,800 to 5,600 feet Mean annual precipitation: 13 to 15 inches Mean annual air temperature: 48 to 50 degrees F Frost-free period: 135 to 150 days Farmland classification: Prime farmland if irrigated Map Unit Composition Nunn, wet, and similar soils:90 percent Minor components:10 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Nunn, Wet Setting Landform:Alluvial fans, stream terraces Landform position (three-dimensional):Base slope, tread Down-slope shape:Linear Across-slope shape:Linear Parent material:Alluvium Typical profile H1 - 0 to 10 inches: clay loam H2 - 10 to 47 inches: clay H3 - 47 to 60 inches: gravelly loam Properties and qualities Slope:1 to 3 percent Depth to restrictive feature:More than 80 inches Drainage class:Somewhat poorly drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat):Moderately low to moderately high (0.06 to 0.60 in/hr) Depth to water table:About 24 to 36 inches Frequency of flooding:NoneRare Frequency of ponding:None Calcium carbonate, maximum content:10 percent Maximum salinity:Nonsaline to very slightly saline (0.0 to 2.0 mmhos/cm) Available water supply, 0 to 60 inches: High (about 9.9 inches) Interpretive groups Land capability classification (irrigated): 2w Land capability classification (nonirrigated): 3s Hydrologic Soil Group: C Ecological site: R067BY038CO - Wet Meadow Hydric soil rating: No Minor Components Heldt Percent of map unit:6 percent Custom Soil Resource Report 13 Ecological site:R067BY042CO - Clayey Plains Hydric soil rating: No Dacono Percent of map unit:3 percent Ecological site:R067BY042CO - Clayey Plains Hydric soil rating: No Mollic halaquepts Percent of map unit:1 percent Landform:Swales Hydric soil rating: Yes 98—Satanta Variant clay loam, 0 to 3 percent slopes Map Unit Setting National map unit symbol: jpyh 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: Prime farmland if irrigated Map Unit Composition Satanta variant and similar soils:90 percent Minor components:10 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Satanta Variant Setting Landform:Terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Parent material:Alluvium Typical profile H1 - 0 to 9 inches: clay loam H2 - 9 to 22 inches: clay loam H3 - 22 to 60 inches: loam Properties and qualities Slope:0 to 3 percent Depth to restrictive feature:More than 80 inches Drainage class:Somewhat poorly drained Runoff class: High Capacity of the most limiting layer to transmit water (Ksat):Moderately low to moderately high (0.06 to 0.20 in/hr) Depth to water table:About 24 to 48 inches Frequency of flooding:OccasionalNone Custom Soil Resource Report 14 Frequency of ponding:None Calcium carbonate, maximum content:15 percent Gypsum, maximum content:10 percent Maximum salinity:Very slightly saline to slightly saline (2.0 to 4.0 mmhos/cm) Available water supply, 0 to 60 inches: Moderate (about 8.7 inches) Interpretive groups Land capability classification (irrigated): 2e Land capability classification (nonirrigated): 4e Hydrologic Soil Group: D Ecological site: R067BY036CO - Overflow Hydric soil rating: No Minor Components Nunn Percent of map unit:5 percent Ecological site:R067BY002CO - Loamy Plains Hydric soil rating: No Caruso Percent of map unit:3 percent Ecological site:R067BY036CO - Overflow Hydric soil rating: No Loveland Percent of map unit:2 percent Ecological site:R067BY036CO - Overflow Hydric soil rating: No Custom Soil Resource Report 15 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 16 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 17 NORTHERNENGINEERING.COM | 970.221.4158 FINAL DRAINAGE REPORT: GATEWAY APARTMENTS FORT COLLINS | GREELEY APPENDIX MAP POCKET DR1 – DRAINAGE EXHIBIT XXXXXX X X XXX XXXX X XXXXXX X X X X X XXXX X X X X X X X X X X X X X X X X X X X X XXXXXXXX/ / / / / / / /XXXX X X X X XXXXX X XXXXXXTTTTTTTEEEEEEEEE/ / / / / / / // / / / / / / // / / / / / / /TWWWWWSWSELECVAULTELECXXXXX/ / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / // / / / / / / /X X XXXXXXXX X CONTROLIRRCONTROLIRRELECELECVAULTELECVAULTELECACWBLBLBLBLBLBL BL BL BL BL BL BL B L B L B L B L BL BLBL BLBLB L BLBL B L BL BL BL B L BL B L BLB L BLBL BLBLBLBLBLBLBLBLBLBLBLSD SD SD SD SD SD SD SD SD SD T ST SVAULTELECXX X X X XXXXXXXV.P.V.P.YIELDYIELDYIELDYIELDSDSDSDSDNPNPNPNPSD SD S D S D S D S D S D NYLOPLAST DO NOT POLLUTEDRAINS TOWATERWAYS DO NOT POLLUTE DRAI N S T O WATE R W A Y S NYLOPLAST DUCTILE IRON NYLOPLAS T DO NOT POLLUTE DRA I N S T O WA T E R W A Y SUDUDNYLOPLASTDO NOT POLLUTE DRAINS TO WATERWAYS UDUDNYLOPLAST DO NOT POLLUTEDRAINS TOWATERWAYS DO NOT POLLUTE DRAINS TO WATERWAYS NYLOPLAST DUCTILE IRON UDNYLOPLASTDO NOT POLLUTE DRAINS TO WATERWAYS NYLOPLASTDO NOT POLLUTE DRAINS TO WATERWAYS UDNYLOPLASTDO NOT POLLUTEDRAINS TOWATERWAYS DO NOT POLLUTE DRAINS TO WATERWAYSNYLOPLAST DUCTILE IRON NYLOPLASTDO NOT POLLUTEDRAINS TOWATERWAYSDO NOT POLLUTE DRAINS TO WATERWAYSNYLOPLAST DUCTILE IRONNYLOPLASTDO NOT POLLUTEDRAINS TOWATERWAYSDO NOT POLLUTE DRAINS TO WATERWAYS NYLOPLAST DUCTILE IRON NYLOPLAST DO NOT POLLUTEDRAINS TO WATERWAYSDO NOT POLLUTE DRAINS TO WATERWAYS NYLOPLAST DUCTILE IRON NYLOPLASTDO NOT POLLUTEDRAINS TOWATERWAYSDO NOT POLLUTE DRAINS TO WATERWAYSNYLOPLAST DUCTILE IRONNYLOPLASTDO NOT POLLUTEDRAINS TOWATERWAYSDO NOT POLLUTE DRAINS TO WATERWAYS NYLOPLAST DUCTILE IRONNYLOPLASTDO NOT POLLUTEDRAINS TOWATERWAYSDO NOT POLLUTE DRAINS TO WATERWAYS NYLOPLAST DUCTILE IRON NYLOPLAS T DO NOT POLLUTEDRAINS TOWATERWAYS DO NOT POLLUTE DRAINS TO WATERWAYS NYLOPLAST DUCTILE IRON NYLOPLAST DO NOT POLLUTEDRAINS TOWATERWAYS DO NOT POLLUTE DRAINS TO WATERWAYS NYLOPLAST DUCTILE IRONXXXXX X X XXXXXXXX X X XXXXXXXXXXXXX XPROSPECT RDSTREET B STREET DSTREET EOWNER: ANDERSONKENNTH E & JULIEANNOWNER: DEADMONDLARRY L & NANCY KOWNER:CULBERTSONDAVID MOWNER: SEA STARLIMITED PARTNERSHIPOWNER: DESELMSROBERT A & KDENISEOWNER:MOODYMARILYNJOANNEGATEWAY AT PROSPECTTRACT BGATEWAY AT PROSPECTTRACT HGATEWAY AT PROSPECTTRACT IGATEWAY AT PROSPECTTRACT DGATEWAY AT PROSPECTTRACT HOWNER: GLANZTHOMAS J/LAURA PTRACT ATRACT BSTORMTECH CHAMBERS 2STORMTECH CHAMBERS 1RAIN GARDEN 1PROPOSED INLETPROPOSED INLETMANHOLE WITH 100-YROVERFLOW WEIRMANHOLE WITH 100-YROVERFLOW WEIRPROPOSED INLETPROPOSED INLETPROPOSED INLETPROPOSEDSIDEWALKCHASEPLANNED INLETSSEE GATEWAY ATPROSPECT PLANSPROPOSED INLETPLANNED FULL SPECTRUMOUTLET STRUCTURESEE GATEWAY AT PROSPECT PLANSPLANNED FULL SPECTRUMOUTLET STRUCTURESEE GATEWAY AT PROSPECT PLANSPLANNEDEMERGENCYOVERFLOW WEIRSEE GATEWAY ATPROSPECT PLANSPLANNEDEMERGENCYOVERFLOW WEIRSEE GATEWAY ATPROSPECT PLANSPROPOSED INLETSPLANNED SIDEWALKCULVERTSEE GATEWAY ATPROSPECT PLANSPROPOSED INLETPLANNED INLETSEE GATEWAY ATPROSPECT PLANSPLANNED RAINGARDEN F5SEE GATEWAY ATPROSPECT PLANSPROPOSED INLETBOXELDER CREEKNATURAL HABITATBUFFER ZONE (NHBZ)BOXELDER CREEKNATURAL HABITATBUFFER ZONE (NHBZ)100-YR WSEL100-YR WSELFEMA 100-YRFLOODPLAINNATURAL HABITATBUFFER ZONE (NHBZ)PROPOSED 100-YRFLOODPLAINPROPOSED 100-YRFLOODWAYEROSION BUFFERLIMITS (TYP.)FEMA 100-YRFLOODWAYPROPOSED INLETPROPOSED CULVERTPROPOSED CULVERTPROPOSEDSIDEWALKCHASEPROPOSED INLETPROPOSED INLETPROPOSEDDRAINAGEEASEMENTPROPOSED INLETE1.1F1.5F5E1.3E1.4F1.1E2F1.4F1.8F3F1.3F2F1.2F1.6F1.7E1.2F4DETENTIONPOND FDETENTIONPOND EBOXELDER CREEK100-YR OVERFLOWCHANNELB O X E L D E R C R E E K LEASING OFFICEAND CLUBHOUSE BUILDING 1BUILDING 2BUILDING 3BUILDING 4BUILDING 5BUILDING 6BUILDING 7BUILDING 8BUILDING 9GARAGE 5GARAGE 6GARAGE 1 GARAGE 2 GARAGE 3 GARAGE 4 f2f1.7f3f1.5f1.6f1.8f1.4f1.2f1.3f1.1f4f5e1.2e1.3e1.4e2e1.1EXISTING 20'DRAINAGE EASEMENTCALL 2 BUSINESS DAYS IN ADVANCE BEFORE YOUDIG, GRADE, OR EXCAVATE FOR THE MARKING OFUNDERGROUND MEMBER UTILITIES.CALL UTILITY NOTIFICATION CENTER OFCOLORADOKnow what'sbelow.before you dig.CallRNORTH( IN FEET )1 inch = ft.Feet0606060120180PROPOSED CONTOURPROPOSED STORM SEWERPROPOSED SWALEEXISTING CONTOURPROPOSED CURB & GUTTERPROPERTY BOUNDARYPROPOSED INLETADESIGN POINTFLOW ARROWDRAINAGE BASIN LABELDRAINAGE BASIN BOUNDARYPROPOSED SWALE SECTION11NOTES:1.REFER TO THE PRELIMINARY DRAINAGE REPORT FOR GATEWAYAPARTMENTS FOR ADDITIONAL INFORMATION.2.PROPOSED FLOODPLAIN AND FLOODWAY LIMITS ARE CONTINGENT ANDSUBJECT TO A FEMA CLOMR APPROVAL.ALEGEND:EFFECTIVE FEMA 100-YR FLOODPLAINEFFECTIVE FEMA 100-YR FLOODWAYPROPOSED 100-YR FLOODPLAINPROPOSED 100-YR FLOODWAYKEYMAPX PROSPECT RDFOR DRAINAGE REVIEW ONLYNOT FOR CONSTRUCTIONRational Flow Summary | Developed Basin Flow RatesBASINTOTALAREA(acres)Tc2(min)Tc100(min)C2C100Q2(cfs)Q100(cfs)F1.11.505.05.00.881.003.7614.92F1.21.315.05.00.901.003.3613.02F1.30.915.05.00.891.002.309.01F1.41.325.05.00.780.982.9312.79F1.50.305.05.00.560.700.482.09F1.60.885.05.00.891.002.248.78F1.70.715.05.00.891.001.807.07F1.81.725.05.00.340.431.677.27F20.585.05.00.871.001.445.79F30.355.05.00.951.000.953.51F41.435.55.50.770.962.8612.46F51.216.46.40.550.691.677.30E1.10.505.05.00.811.001.154.98E1.21.205.05.00.780.982.5811.25E1.31.039.09.00.570.711.225.34E1.40.697.37.30.290.360.492.15E20.805.05.00.620.781.426.19F1.1 to F1.8, F2 to F512.218.08.00.750.9420.2488.39F1.1 to F1.3, F45.145.05.00.861.0012.2149.52F1.5 to F1.7, F22.475.05.00.851.005.9924.61E1.1 to E1.4, E24.225.95.90.620.786.4328.08E1.2 to E1.32.235.15.10.680.853.9317.13OWNER:REVISIONS:SHEET TITLE:GATEWAY APARTMENTS I-25 AND PROSPECT ROAD FORT COLLINS, COLORADOROCKEFELLER ACQUISITIONS LLC1401 LAWRENCE STREET, SUITE 1600DENVER, COLORADO 80202303.807.9005N O T F O R C O N S T R U C T I O N These drawings areinstruments of serviceprovided by NorthernEngineering Services, Inc.and are not to be used forany type of constructionunless signed and sealed bya Professional Engineer inthe employ of NorthernEngineering Services, Inc.of 17ENGINEERNGIEHTRONRNC6.0117DRAINAGEEXHIBITC6.01Pond IDTotal StorageVolume (ac-ft)WQCV (ac-ft)EURV(ac-ft)Final ReleaseRate (cfs)Pond E0.4820.0740.1347.2Pond F1.6800.2670.52614.6DETENTION POND SUMMARY