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Reports - Drainage - 09/01/2025 (2)
OVERALL DRAINAGE REPORT FOR STRAUSS LAKES CITY OF FORT COLLINS COUNTY OF LARIMER STATE OF COLORADO PREPARED FOR: Cottonwood Land and Farms, LLC PO Box 229 Boulder, CO 80306 PREPARED BY: Civil Resources, LLC 8308 Colorado Blvd. Suite 200 Firestone, Colorado 80504 PREPARED: NOVEMBER 2024 CIVIL RES----.'0URCLS,LLC REVISED: SEPTEMBER 2025 Overall Drainage Report Strauss Lakes Table of Contents Paqe 1.0 BACKGROUND.....................................................................................................................................................5 1.1 General Location...........................................................................................................................................5 1.2 Existing Site Information................................................................................................................................5 1.3 Floodplain Information...................................................................................................................................5 1.4 Master Drainage Basin Description...............................................................................................................6 1.5 Previous Studies...........................................................................................................................................6 1.6 Project Description........................................................................................................................................7 2.0 DRAINAGE DESIGN CRITERIA............................................................................................................................7 2.1 Regulations...................................................................................................................................................7 2.2 Hydrologic& Hydraulic Criteria.....................................................................................................................7 3.0 PROPOSED DRAINAGE FACILITIES...................................................................................................................8 3.1 General Concept...........................................................................................................................................8 3.2 Drainage System Outfall...............................................................................................................................9 3.3 Low Impact Development(LID).....................................................................................................................9 3.4 Municipal Separate Storm Sewer System (MS4) Permit.............................................................................10 3.5 Detention & Flood Control...........................................................................................................................10 4.0 CONCLUSIONS...................................................................................................................................................10 4.1 Compliance with Criteria.............................................................................................................................10 4.2 Drainage Concept.......................................................................................................................................11 5.0 REFERENCES ....................................................................................................................................................11 Prepared:November 2024;Revised:September 2025 Page 2 of 11 Overall Drainage Report Strauss Lakes List of Appendices APPENDIX A FIGURES&TABLES Project Vicinity Map Hydrologic Soils Map& Table Effective Flood Insurance Rate Map Fort Collins Risk Map Fort Collins Stormwater Criterial Manual(select pages) APPENDIX B REFERENCE REPORTS Fox Meadows Basin Selected Plan— Water Quality Improvements Addendum to the Final Design Report for the Fossil Creek Reservoir Inlet Ditch Storm Water Overflow Memorandum:Hydraulic Analysis of Fossil Creek Reservoir Inlet Ditch Final Drainage and Erosion Control Report Rigden Farm—Filing Six APPENDIX C HYDROLOGIC& HYDRAULIC COMPUTATIONS East Horsetooth Road Historic Runoff Calculations Historic SWMM Model Preliminary Proposed SWMM Model WQCV Calculations Constructed Wetland Pond Calculations Modified FAA Calculations Hydraflow Express Output APPENDIX D DRAINAGE PLANS Historic Drainage Plan Proposed Drainage Plan Prepared:November 2024;Revised:September 2025 Page 3 of 11 Overall Drainage Report Strauss Lakes ENGINEER'S CERTIFICATION OF DRAINAGE REPORT "I hereby certify that this report for the overall drainage design of Strauss Lakes was prepared by me(or under my direct supervision) in accordance with the provisions of the Fort Collins Stormwater Criteria Manual for the owners thereof." Registered Professional Engineer State of Colorado No.40551 Prepared:November 2024;Revised:September 2025 Page 4 of 11 Overall Drainage Report Strauss Lakes 1.0 BACKGROUND 1.1 General Location The Strauss Lakes project is located northeast of the intersection of Ziegler Road and East Horsetooth Road, and is situated in Section 28, Township 7 North, Range 68 West of the 61h Principal Meridian, County of Larimer, State of Colorado. The project area includes parcel 8728000003, located within the City of Fort Collins, and parcel 8728000009, located in unincorporated Larimer County.The Site is bounded by Ziegler Road to the west, East Horsetooth Road to the south, Great Western Railway to the north, and the Boxelder Ditch to the northeast. Refer to Appendix A for a Project Vicinity Map. The purpose of this report is to accompany an annexation and ODP application. The ODP establishes overall land uses for the property, but does not propose specific layouts or design. This report serves to establish the overall drainage objectives to be followed in future final drainage reports for each phase of development 1.2 Existin_p Site Information The Strauss Lakes project Site is currently undeveloped with native grass land cover. The property slopes west to east with grades generally ranging from 0.02%to 5.2%. Native,on-site soils can be classified as approximately 26%Hydrologic Soil Group B, 29% Group C, and 45% Group D. Refer to Appendix A for soils map and classification table. A significant portion of the Site has been filled using material removed from a gravel pit located north of the Great Western Railroad. There are approximately 2.91 acres of existing wetlands and 12.42 acres of open water within the property boundary. Refer to the Ecological Characterization Study—Strauss Lakes Residential Development, prepared by ERO Resources Corporation. The Fossil Creek Reservoir Inlet Ditch (FCRID) traverses the Site, separating the City parcel (8728000003) from the unincorporated land (8728000009).The FCRID conveys irrigation flows diverted from the Cache la Poudre River, as well as treated discharge from the Fort Collins wastewater treatment plant, to the Fossil Creek Reservoir.A spill structure for the ditch is located along the south property line,just north of East Horsetooth Road.The spill structure is further described in section 1.4.There is flow in the FCRID year-round,and some waters are used to support regional oil and gas activities. The Boxelder Ditch is located within the north end of the Site and flows southeast along the eastern boundary of the Site. The Boxelder Ditch diverts irrigation flows from the Cache la Poudre River, and conveys flows to various on-site and off- site headgates downstream of the Site.A control structure for the ditch is located at the southeast corner of the Site. The Foothills Channel Outfall (FCO) runs along the southern property line of the unincorporated parcel (8728000009), along the north side of East Horsetooth Road. The FCO is an overflow channel for the FCRID, which conveys flows east along East Horsetooth Road and discharges to the Cache la Poudre River. The FCO is normally dry, and only has flows during significant wet weather events when the FCRID overflows to the FCO. 1.3 Floodplain Information A portion of the Site, southwest of the Boxelder Ditch, lies within Zone X, of the Cache La Poudre River, per Federal Emergency Management Agency(FEMA) Flood Insurance Rate Map (FIRM) number 08069C0992G.Zone X is defined as the area of 0.2%annual chance flood (500-year floodplain).A portion of the Site north of the Boxelder Ditch is located within Zone AE, the 1.0%annual chance flood (100-year floodplain).A copy of the effective FIRM is included in Appendix A. The floodplain in this area is currently being remapped by consultants for the Colorado Water Conservation Board and FEMA.A copy of the preliminary map (Fort Collins Risk Map) is included in Appendix A. The preliminary mapping indicates no portion of the Site will be located in the 100-year floodplain. Prepared:November 2024;Revised:September 2025 Page 5 of 11 Overall Drainage Report Strauss Lakes 1.4 Master Draina_pe Basin Description A portion of the Site is located within the Cache La Poudre River Master Drainage Basin and the remaining portion is within the Fox Meadows Master Drainage Basin. The master drainage reports for both of these basins are in the process of being updated. 1.4.1 Cache La Poudre Master Drainage Basin The Cache La Poudre River Master Drainage Basin (Poudre Basin)was analyzed in the Cache La Poudre River Master Drainageway Plan, prepared by Ayres Associates in August 2001. This report discusses several problem drainage areas along the Cache la Poudre River, including sites upstream and downstream of the subject Site, but none directly impacting the Site. The Riverbend Ponds Area is located upstream of the subject Site, northwest of the City's wastewater treatment plant. The report identifies significant flooding and flood damage in this area. Several alternatives are presented in the report including the construction of levees, modification of existing levees, and the construction of a weir. These improvements have been completed. 1.4.2 Fox Meadows Drainage Basin The Fox Meadows Drainage Basin was evaluated in the following master reports: • Fox Meadows Basin Drainage Master Plan Update—50-Year Alt. Plan, prepared by ICON Engineering, Inc. on December 61h, 2002. • Fox Meadows Basin Drainage Master Plan Update Phase A—Baseline Hydraulics and Problem Identification Report, prepared by ICON Engineering, Inc. and revised February 2003. • Fox Meadows Basin Drainage Master Plan Update Selected Plan Report, prepared by ICON Engineering, Inc. and revised February 2003. These reports state that much of the master basin has been developed,with little development potential remaining, and identifies several drainage problems within the master basin including overtopping detention ponds, insufficient freeboard of irrigation ditches,and conveyance channels and roadway overtopping. The subject Site is located on the upstream end of the master basin, and the problems identified in these reports occur downstream of the Site. Several mitigation efforts are proposed in the plans; however, it is unknown which, if any, of these solutions have been implemented. As indicated on the Fox Meadows Basin Selected Plan— Water Quality Improvements figure,the southwest corner of the Site (8728000003)was considered as an potential location for a water quality pond to serve the Fox Meadows Drainage Basin (see Appendix B for referenced figure). Per discussions between City staff and the Developer, the Strauss Lakes development will not need to accommodate a water quality pond to treat off-site flows. 1.5 Previous Studies The Site has been included in previous studies of the Fossil Creek Reservoir Inlet Ditch (FCRID),which traverses the Site. The Foothills Channel Outfall (FCO)was first described in the Final Design Report for the Fossil Creek Reservoir Inlet Ditch Storm Water Overflow prepared by Donohue&Associates, Inc. in February 1988.The FCO was designed to convey excess flows from the FCRID to the Cache la Poudre River. Flow is diverted from the FCRID via a spill structure located north of East Horsetooth Road. The FCRID was initially designed to convey the total 100-year peak flow to the structure,which is 1,160 cfs.The Addendum to the Final Design Report for the Fossil Creek Reservoir Inlet Ditch Storm Water Overflow prepared by Donohue&Associates, Inc. in September 1988, limits this flow to 860 cfs,which means the Prepared:November 2024;Revised:September 2025 Page 6 of 11 Overall Drainage Report Strauss Lakes control gate passes 300 cfs to the FCRID, south of East Horsetooth Road, during the 100-year peak storm. The flow in the FCO was most recently analyzed by Anderson Consulting Engineers, Inc. in the April 30, 2020 memorandum Hydraulic Analysis of Fossil Creek Reservoir Inlet Ditch Between Cache la Poudre River and Harmony Road for Future Strauss Lake Development. This study found that a maximum of 523 cfs flows through the FCO, downstream of the FCRID spill structure.This results in an available capacity of 337 cfs in the FCO at this location. The FCRID was also evaluated by Anderson Consulting Engineers, Inc. in the 2002 Hydraulic Analysis and Design of the Fossil Creek Reservoir Inlet Ditch Controlled Spill System. The information in this report is superseded by the 2020 memorandum. See Appendix B for relevant excerpts of the abovementioned reports. 1.6 Project Description The Strauss Lakes Project proposes to develop the approximately 159-acre subject Site into a mixed-use neighborhood. The neighborhood will consist of both residential units(townhomes, single-family homes, paired homes, and multi-family homes)and commercial units(restaurant, retail, and neighborhood support services).This development will require both annexation of the unincorporated parcel (8728000009) into the City, and rezoning of the Site to a combination of LMN and MMN.The currently annexed parcel (8728000003) is zoned Low Density Mixed-Use Neighborhood District(LMN). Related neighborhood infrastructure will include roadways, alleys, parks,trails,water quality improvements,on-and off- site utilities, local flood control/detention measures, access points off of Ziegler Road and East Horsetooth Road, and roadway improvements to East Horsetooth Road. The development Site is adjacent to the Rigden Farm, Dakota Ridge, and Stone Ridge developments, located west of Ziegler Road, Rigden reservoir to the east, Environmental Learning Center, Running Deer Natural Area, and Cache la Poudre River to the north, and Topminnow Natural Area and unincorporated residential homes to the south. 2.0 DRAINAGE DESIGN CRITERIA 2.1 Regulations The proposed drainage design will comply with the regulations set forth in the Fort Collins Stormwater Criteria Manual (FCSCM), revised December 2018. 2.2 Hydrologic&Hydraulic Criteria The hydrology of the Site and the hydraulic of the stormwater system will be analyzed per the methods outlined in Chapter 5 of the FCSCM. The following methods will be presented in the final drainage report. • EPA Stormwater Management Model (SWMM) version 5.2 will be used to estimate the 2 and 100-year peak developed runoff as the minor and major storm events, respectively. The input parameters listed in Table 4.1-1 and the intensity-duration-frequency values from Table 4.1-4 of the FCSCM will be used to model the subcatchments and rain gauges. • Impervious values for the Site will be determined by land use for conceptual design, per Table 4.1-2 in the FCSCM, and will later be revised by surface type, per Table 4.1-3. • Inlets will be sized to capture the peak flow rate from the minor 2-year storm(minus the allowable street capacity), per chapter 12, section 1.4 of the FCSCM. • The water quality capture volume (WQCV)will be calculated per equations 7-1 and 7-2 in the FCSCM. • The on-site conveyance swale and emergency spillways will be sized using the Hydraflow Express extension for Prepared:November 2024;Revised:September 2025 Page 7 of 11 Overall Drainage Report Strauss Lakes Autodesk Civil 3D. • The 100-year detention volumes will be determined using both the Modified FAA method, and EPA Stormwater Management Model(SWMM)version 5.2.The subcatchment input parameters for SWMM were taken from Table 4.1-1 in the FCSCM. 3.0 PROPOSED DRAINAGE FACILITIES 3.1 General Concept For the purposes of this Overall Drainage Report, the Site has been divided into three drainage basins: the West Site, located west of the FCRID, the East Site, located east of the FCRID, and East Horsetooth Road. Furthermore, the East Site has been subdivided into five(5)conceptual 20-acre sub-basins.The basin shapes are arbitrary, and not based on a specific road layout or grading scenario, but were developed to estimate runoff in order to preliminarily size a drainage swale parallel to the Boxelder Ditch. The stormwater systems for the West Site and East Site will function independently of one another. See Appendix D for the Overall Drainage Plan. 3.1.1 West Site The West Site will generally maintain the historic drainage pattern by directing flow northeast, via paved conveyances, inlets, and storm sewer. Captured runoff will be directed to a detention pond, located in the northern corner of the West Site. This pond will be sized to detain the developed 100-year tributary flow, and discharge to the FCRID at a rate equal to or below the 2-year historic discharge rate of 0.90 cfs. The drainage area of the West Site is approximately 12.08 acres.The layout and density of the West Site is unknown at this point;therefore the impervious value of the West Site is conservatively assumed to be 90% (high density) per Table 4.1-2 of the FCSCM. The impervious value will be further refined in subsequent drainage reports using Table 4.1-3. The configuration and grading of the West Site may also require the detention volume be provided by two ponds, one located on the north portion of the Site, and the other along the eastern portion. The 100-year developed runoff of the West Site is estimated to be 118.88 cfs, per SWMM. See Appendix C for SWMM summary tables. 3.1.2 East Site The East Site currently drains east towards the Boxelder Ditch.The Boxelder intercepts minor storms, and major events either overtop the ditch and enter Rigden Reservoir, or enter the FCO. The proposed design will intercept runoff prior to entering the Boxelder Ditch. The drainage area of the East Site is approximately 99.10 acres.The layout and density of the East Site is unknown at this point;therefore the impervious value of the East Site is conservatively assumed to be 90% (high density)per Table 4.1-2 of the FCSCM.The impervious value will be further refined in subsequent drainage reports using Table 4.1-3.The 100-year developed runoff of each subbasin of the East Site was calculated using SWMM to be 133.77 cfs,for a total runoff of 668.85 cfs. See Appendix C for SWMM summary tables. Each drainage subbasin will discharge to a conveyance swale located along the east property line,just west of the Boxelder Ditch. Forebays will be provided at each inlet to this conveyance swale to provide energy dissipation,trash collection, and sediment control. The conveyance swale will flow southeast to a constructed wetland pond (CWP), located at the southeast corner of the East Site. The swale was preliminarily sized for the cumulative flow from each of the five conceptual 20-acre basins, which resulted in a maximum top width of 62-feet. The Hydraflow Express analysis is included in Appendix C. The CWP will provide water quality treatment(further described in section 3.2)and flood control for the 100-year major storm event. Runoff from the major storm will be detained in the pond, and released to the Foothills Channel Outfall (FCO),via an outlet structure.The detained runoff will be released at a rate equal to or below the available capacity of the FCO, minus the discharge from the West Site and East Horsetooth Road.There will be an emergency spillway located on the south side of the pond,which will be sized to pass the undetained 100-year runoff from the pond tributary area, per section 3.2 of the FCSCM. The spillway will discharge south to the FCO. Prepared:November 2024;Revised:September 2025 Page 8 of 11 Overall Drainage Report Strauss Lakes 3.1.3 East Horsetooth Road The Site historically receives off-site flows from East Horsetooth Road,from the intersection with Ziegler Road to the FCRID crossing.The development of the Strauss Lakes Site will require improving the roadway to a two-lane arterial street, per Figure 7-3F of the Larimer County Urban Area Street Standards(LCUASS). Costs for this roadway construction will be shared by the City and the developer. For a Site frontage of approximately 2,950 linear feet,this results in an impervious area of 4.33 acres.The future impervious value of the roadway is assumed to be 95%, resulting in a 100-year developed runoff of approximately 43.44 cfs, per SWMM. See Appendix C for SWMM summary tables. The development will be responsible for providing water quality treatment of this new impervious area.The location of the FCO creates a barrier to treating the roadway runoff on-site;therefore, it is proposed to treat the runoff from East Horsetooth Road using an extended detention basin, located south of the road on City of Fort Collins property(parcel 8733231902). The exact location of this stormwater facility will need to be coordinated with the City. Developed runoff will be captured in street inlets, and conveyed via storm sewer to the detention pond. The detention pond will be sized for the WQCV and 100-year storage volume of the full-width roadway buildout, and will discharge to the FCO.The pond outlet structure will be designed to discharge the 100-year developed runoff at or below the historic 2-year runoff rate of 2.34 cfs, as calculated using the Rational Method. 3.2 Drainage System Outfall Per prior agreements between Cottonwood Land and the City of Fort Collins, developed runoff from the development will be allowed to discharge to the Foothills Channel Outfall (FCO). As previously discussed, the FCO was most recently studied by Anderson Consulting Engineers, Inc. in a memorandum dated April 30, 2020. This study determined that the maximum overflow from the FCRID to the FCO was 523 cfs. Assuming the 100-year capacity of the channel is 860 cfs, per the 1988 report, the maximum release rate from the Site is 337 cfs. For the purpose of this overall report, a reduction factor of 25%was applied to this capacity, resulting in an allowable release rate of 252.75 cfs.The 100-year capacity will need to be verified through hydraulic modeling of the FCO, and final design of the project may utilize the modeled excess capacity of the FCO. Developed runoff from the West Site will be detained in the detention pond and discharged to the FCRID at a rate equal to or below the historic 2-year runoff rate of 0.90 cfs.The Horsetooth Road detention pond outlet structure will be designed to release the 100-year developed runoff from the roadway at or below the historic 2-year runoff rate of 2.34 cfs. This leaves 249.51 cfs of receiving capacity in the FCO.The outlet structure of the constructed wetland pond will be designed to release the 100-year storage volume at or below this remaining capacity.To discharge at this high rate,the CWP outlet structure will likely be constructed from a combination of orifices,weirs, and outflow channels. All runoff discharged to the FCO will flow east along the north side of East Horsetooth Road,eventually discharging to the Cache la Poudre River just east of Strauss Cabin Road. 3.3 Low Impact Development(LID) The City of Fort Collins requires the implementation of Low Impact Development (LID) systems to treat 75% of newly added or modified impervious areas. Several LID systems were evaluated for the East Site, including bioretention, infiltration trenches, and constructed wetlands. Bioretention rain gardens were preliminarily sized to treat the WQCV of the East Site. Per Mile High Flood District(MHFD) design guidelines for Bioretention Systems (Fact Sheet T-3), the maximum WQCV depth is 1-foot, which results in a required rain garden treatment area of approximately 3.6 acres. Fort Collins requires a minimum of 30 inches of filter media and bedding material, which would total approximately 14,500 cubic yards of material for the treatment area. Because of the size requirements and volume of bedding material required,rain gardens were determined to be impractical for the East Site. Prepared:November 2024;Revised:September 2025 Page 9 of 11 Overall Drainage Report Strauss Lakes Infiltration trenches cannot be implemented because of the high groundwater levels on the Site.Therefore, a constructed wetland pond (CWP) is proposed to treat the WQCV of the East Site. The permanent pool volume was calculated per equation RP/CWP-1 of the MHFD Fact Sheet T-7, and was determined to be 2.69 acre-feet. See Appendix C for preliminary sizing calculations of the CWP. The permanent pool of the CWP will be maintained through exposed ground water, which will require a pond well permit, as well as water rights. The estimated area of exposed groundwater is approximately 3.78 acres, which includes the constructed wetland pond (2.91 acres) and the conveyance swale (0.87 acres). The 2.91 acres of permanent wetland will mitigate the effects of removing 0.14 acres of existing wetland on the West Site, resulting in 2.77 acres of wetland available for stormwater mitigation. Per discussion with City staff, LID will not be required to treat runoff from the East Horsetooth Road widening. The impervious area of East Horsetooth Road will account for less than 25%of the entire Site,and therefore can be excluded. LID for the West Site will be implemented locally through the use of grass buffers,grass swales, rain gardens, permeable pavers, and other LID features, as needed, to meet the 75% requirement of the City. LID features will not be provided within right-of-way,or within single-family private lots, per section 6.1 of the FCSCM. 3.4 Municipal Separate Storm Sewer System(MS4)Permit Per the Colorado Department of Public Health and Environment's (CDPHE) COR090000 Municipal Separate Storm Sewer Systems(MS4) Permit,the Site must meet one of the post-construction base design standards. This Site will be designed to meet the WQCV standard, by capturing and treating 100%of the WQCV for the applicable development site (excluding up to 1 acre).This standard will be met through the use of a detention pond, as described in section 3.1.1, and a constructed wetland pond, as described in section 3.1.2. 3.5 Detention&Flood Control The 100-year runoff of the West Site will be detained in an extended detention pond and discharged to the FCRID via an outlet structure. Per SWMM, the preliminary 100-year developed runoff from the West Site is 118.88 cfs, and the outlet structure will be designed to release the 100-year developed runoff at a rate equal to or below the SWMM-calculated 2- year historic runoff rate of 0.90 cfs. Per the Modified FAA Procedure, as described in section 2.3 of the FCSCM, the 100- year storage volume is estimated to be 2.97 acre-feet. The developed 100-year runoff from East Horsetooth Road will be detained in an extended detention basin, located south of the road,on City property.The exact location of this pond will need to be coordinated with the City.The 100-year storage volume was estimated to be 1.23 acre-feet, per the Modified FAA Procedure. The available pond working depth south of East Horsetooth Road is estimated to be 4.5-feet, based on preliminary survey, and one-foot of freeboard is required, which results in an available storage depth of 3.5 feet. The outlet structure of this pond will be designed to release the 100-year detention volume at or below the historic 2-year runoff rate of 2.34 cfs. Detained runoff will discharge to the FCO. The 100-year runoff of the East Site will be detained in the constructed wetland pond,and will be released to the receiving body(FCO)at a controlled rate,via an outlet structure. Preliminary sizing of the constructed wetland pond was performed using SWMM, and the maximum storage volume was determined to be 469,407 cubic feet, or 10.78 acre-feet. For a preliminary WQCV of 3.58 acre-feet, this results in a required 100-year storage volume of 7.20 acre-feet. A preliminary pond with a footprint of approximately 5 acres was evaluated in SWMM.See Appendix C for SWMM summary tables.The CWP outlet structure will be designed to release the 100-year volume at or below 249.51 cfs,which is equal to the capacity of the FCO(252.75 cfs), minus the detained discharge from the West Site and East Horsetooth Road (3.24 cfs). 4.0 CONCLUSIONS 4.1 Compliance with Criteria This overall drainage report is in compliance with the provisions outlined in the Fort Collins Stormwater Criteria Manual. Prepared:November 2024;Revised:September 2025 Page 10 of 11 Overall Drainage Report Strauss Lakes 4.2 Drainage Concept The proposed drainage system will improve Site drainage through the following methods: • The 100-year developed runoff from the West Sites will be detained and released to the FCRID at XX • The 100-year developed runoff from the East Site will be released to the Foothills Channel Outfall at a rate equal to the remaining capacity of the channel. • Low Impact Development systems will be implemented to treat a minimum of 75% of the new or modified impervious area. • 100%of the water quality capture volume of the applicable development site(excluding up to 1 acre)will be treated, per CDPHE MS4 requirements. The preliminary design of the drainage system is in accordance with applicable design standards and criteria, and is therefore not anticipates to have an adverse impact on the existing drainage conditions of the Site nor its immediate vicinity. 5.0 REFERENCES • Cache la Poudre River Master Drainageway Plan. Ayres Associates, EDAW.August 2001. • Final Design Report for the Fossil Creek Reservoir Inlet Ditch Storm Water Overflow. Donohue&Associates, Inc. March 1988. o Addendum to the Final Design Report for the Fossil Creek Reservoir Inlet Ditch Storm Water Overflow. Donohue&Associates, Inc. September 1988. • Final Drainage and Erosion Control Report Rigden Farm—Filing Six. JR Engineering. Revised February 8, 2002. • Fort Collins Stormwater Criteria Manual. City of Fort Collins. December 2018. • Fox Meadows Basin Drainage Master Plan Update—50-Year Alt. Plan. ICON Engineering, Inc. December 6, 2002. • Fox Meadows Basin Drainage Master Plan Update Phase A—Baseline Hydraulics and Problem Identification Report. ICON Engineering, Inc. Revised February 2003. • Fox Meadows Basin Drainage Master Plan Update Selected Plan Report. ICON Engineering, Inc. Revised February 2003. • Hydraulic Analysis of Fossil Creek Reservoir Inlet Ditch Between Cache la Poudre River and Harmony Road for Future Strauss Lake Development. Anderson Consulting Engineers, Inc.April 30, 2020. • Hydraulic Analysis of the Fossil Creek Reservoir Inlet Ditch Controlled Spill System. Anderson Consulting Engineers, Inc. December 2,2002. • Urban Storm Drainage Criteria Manual. Mile High Flood District. Partially updated March 2024. Prepared:November 2024;Revised:September 2025 Page 11 of 11 APPENDIX A Figures & Tables Strauss Lakes Vicinity Map Fort Collins, CO y ` u E L aulrel St_. c • e Si LOWE10 u s 'I ry r E Elizabeth-St ; i,SCHOOL r �HISTORI'C I FORT COLLINS HIGI•s � _' � '� d r R a`. iP .i�t�t 6 t Rd ,• E;Prospect Rd' �,,, ` ,. �1 ® E Prospect Rd '_ Pr•spect - �t • s - Z. E StLiait St _ OE914 :s_ SOUTH COLLEGE-HEIGHTS " d ` " - �, �, SC.OTCH;PINES t=-` '. d z R ;RIrGDEN FARM a .j SOUTH MOOR VILLAGE enter - m , �� i � Sfiya ss Lakes E v s : lorsetooth n _;,. -. DHorsetodth-RdGrwRd ., ENGLISH RANCH - JTi�IAN PARK `,° Q! �' .,� �,. THE LANDINGS 9 t ■ � a ] +. _ O ARK,* E Goggle _ DE ' HILLS' ` OAKR AGE • - _ y o'n Hydrologic Soil Group—Larimer County Area,Colorado R: (Strauss Lakes) 0 o 498100 498300 498500 498700 498900 499100 499300 40°33'13"N 40°33 13"N —r ffi 9� 9C�3 N ffi �i ' C�3 S I Nlap t be valid at this Scal=. 40°32'11"N — 40°32'11"N 498100 498300 498500 498700 498900 499100 499300 3 3 Map Scale:1:9,330 fi printed on A portrait(8.5"x 11")sheet. b Meber N s ° 0 100 200 400 600 Feet 0 450 900 1800 2700 Map projection:Web Mercator Comer coordinates:WGS84 Edge tics:UTM Zone 13N WGS84 USDA Natural Resources Web Soil Survey 7/12/2024 Conservation Service National Cooperative Soil Survey Page 1 of 4 Hydrologic Soil Group—Larimer County Area,Colorado (Strauss Lakes) MAP LEGEND MAP INFORMATION Area of Interest(AOI) 0 C The soil surveys that comprise your AOI were mapped at Area of Interest(AOI) 0 CID 1:24,000. Soils © D Warning:Soil Map may not be valid at this scale. Soil Rating Polygons A Not rated or not available Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil F—] AID Water Features line placement.The maps do not show the small areas of Streams and Canals contrasting soils that could have been shown at a more detailed 0 B scale. Transportation B/D *.. Rails Please rely on the bar scale on each map sheet for map 0 C measurements. � Interstate Highways 0 C/D US Routes Source of Map: Natural Resources Conservation Service Web Soil Survey LIRL: 0 D Major Roads Coordinate System: Web Mercator(EPSG:3857) 0 Not rated or not available Local Roads Maps from the Web Soil Survey are based on the Web Mercator Soil Rating Lines Background projection,which preserves direction and shape but distorts q distance and area.A projection that preserves area,such as the Aerial Photography Albers equal-area conic projection,should be used if more .-.. AID accurate calculations of distance or area are required. ++� B This product is generated from the USDA-NRCS certified data as ti B/D of the version date(s)listed below. C Soil Survey Area: Larimer County Area,Colorado Survey Area Data: Version 18,Aug 24,2023 r.i CID Soil map units are labeled(as space allows)for map scales ... D 1:50,000 or larger. Not rated or not available Date(s)aerial images were photographed: Jul 2,2021—Aug 25, Soil Rating Points 2021 p A The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background E3 AID imagery displayed on these maps.As a result,some minor B shifting of map unit boundaries may be evident. B/D USDA Natural Resources Web Soil Survey 7/12/2024 Conservation Service National Cooperative Soil Survey Page 2 of 4 Hydrologic Soil Group—Larimer County Area,Colorado Strauss Lakes Hydrologic Soil Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 22 Caruso clay loam,0 to 1 D 79.3 43.7% percent slope 35 Fort Collins loam,0 to 3 C 22.1 12.2% percent slopes 53 Kim loam, 1 to 3 percent B 16.5 9.1% slopes 62 Larimer-Stoneham B 14.1 7.8% complex,3 to 10 percent slopes 64 Loveland clay loam,0 to C 0.0 0.0% 1 percent slopes 73 Nunn clay loam,0 to 1 C 11.1 6.1% percent slopes 74 Nunn clay loam, 1 to 3 C 0.31 0.1% percent slopes 101 Stoneham loam, 1 to 3 B 10.8 6.0% percent slopes 102 Stoneham loam,3 to 5 C 3.5 1.9% percent slopes 105 Table Mountain loam,0 B 15.1 8.3% to 1 percent slopes 136 Water 8.6 4.7% Totals for Area of Interest 1+81.3 100.0% USDA Natural Resources Web Soil Survey 7/12/2024 Conservation Service National Cooperative Soil Survey Page 3 of 4 Hydrologic Soil Group—Larimer County Area,Colorado Strauss Lakes Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D)and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential)when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential)when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher USDA Natural Resources Web Soil Survey 7/12/2024 Conservation Service National Cooperative Soil Survey Page 4 of 4 NOTES TO USERS Cache La LEGEND This map is for use in administering the National Flood Insurance Program. It Poudre River SPECIAL FLOOD HAZARD AREAS (SFHAs) SUBJECT TO does not necessarily identify all areas subject to flooding, particularly from local Split R a INUNDATION BY THE 1% ANNUAL CHANCE FLOOD drainage sources of small size. The community map repository should be FT 894 105,00,00.01, The 1% annual chance flood (100-year flood), also known as the base flood, is the flood consulted for possible updatedor additional flood hazard information. 105*01'52.5" JOINS PANEL 0984 3135000 40133'45.0" -X:.`.:` that has a 1% chance of being equaled or exceeded in any given year. The Special 40133'45.0" X X.:X.l.........._: ............................. ........... .... ..... of Special Flood Hazard incl Zones A, AE, AH, AD, AR, A99, V and VE. The Base To obtain more detailed information in areas where Base Flood Elevations RIVERBEND COURT ZOINEA ............... . .... ......... . L`..................... -surface elevation of the 1%annual chance flood. ................ (BFEs) and/or floodways have been determined, users are encouraged to consult Flood Elevation is the water . ....... ............ .........- LARIMER COUNTY tp, the Flood Profiles and Floodway Data and/or Summary of Stillwater Elevations ............................... ZONE A No Base Flood Elevations determined. UNINCORPORATED AREAS XI E, tables contained within the Flood Insurance Study (FIS) report that accompanies CITY OF FORT COLLINS ZONEAE Base Flood Elevations determined. 080101 .............................. .................... this FIRM. Users should be aware that BFEs shown on the FIRM represent .. .... ......... ............... ..................... 080102 rounded whole-foot elevations. These BFEs are intended for flood insurance ZONEAH Flood depths of 1 to 3 feet (usually areas of ponding); Base Flood Elevations determined. rating purposes only and should not be used as the sole source of flood PROFILE FLOODING EFFECTS FROM 489 Boxelder Creek 1-25 Split 44 000M elevation information. Accordingly, flood elevation data presented in the FIS ....I..:.-. 13ASE LINE kCHE LAPOUDRE RIVER 90 N ZONE AO Flood depths of 1 to 3 feet (usually sheet flow on sloping terrain); report should be utilized in conjunction with the FIRM for purposes of os -ZONE AE PROFILE BASE LINE average depths determined. For areas of alluvial fan flooding, velocities Ditc vers n SPLIT L.PATH construction and/or floodplain management. —ZONE AE also determined. are:: ZONE AR Special Flood Hazard Area formerly protected from the 1% annual ;0 Coastal Base Flood Elevations shown on this map apply only landward chance flood by a flood control system that was subsequently of 0.0' North American Vertical Datum of 1988 (NAVD 88). Users of this decertified. Zone AR indicates that the former flood control system is X.: 4905 FIRM should be aware that coastal flood elevations are also provided in the being restored to provide protection from the 1% annual chance or 3 greater flood. 0! Summary of Stillwater Elevations table in the Flood Insurance Study report for this jurisdiction. Elevations shown in the Summary of Stillwater Elevations ZONE A99 Area to be protected from 1% annual chance flood by a Federal table should be used for construction and/or floodplain management purposes MCLAUGHLIN LANE flood protection system under construction; no Base Flood Elevations when they are higher than the elevations shown on this FIRM. determined. __-Boxelder Creek 1-25 V, Split Overflow ZONE V Coastal flood zone with velocity hazard (wave action); no Base Flood 20 Elevations determined. Boundaries of the floodways were computed at cross sections and interpolated x Boxelder CreeA ...... .. ... 4899 between cross sections. The floodways were based on hydraulic considerations ZONEVE Coastal flood zone with velocity hazard (wave action); Base Flood with regard to requirements of the National Flood Insurance Program. Floodway LL0488 Elevations determined. X [it Levee widths and other pertinent floodway data are provided in the Flood Insurance 21 4885 Study report for this jurisdiction. 25 FLOODWAY AREAS IN ZONE AE 4882 D X ' 1171:�' The floodway is the channel of a stream plus any adjacent floodplain areas that must be Certain areas not in Special Flood Hazard Areas may be protected by flood NOTE:THISAREA IS SHOWN AS BEI NG PROTECTED control structures. Refer to Section 2.4 "Flood Protection Measures" of kept free of encroachment so that the 1% annual chance flood can be carried without fROM THE 11,�PERCENT-ANNUAL-,CHANCE OR GREATER substantial increases in flood heights. the Flood Insurance Study report for information on flood control structures �FLOOD HAZARD BY A LEVEE SYSTEM. OVERTOPPING X for this jurisdiction. OR.FAILURE OF ANY LEVEE SYSTEM IS POSSIBLE.�,.FOR.:. 4tfdU ADDITIONAL INFORMATION,SEETHE 11.A.CCREDITED G OTHER FLOOD AREAS The projection used in the preparation of this map was Colorado State LEVEE NOTE�l IN NOTES TOMSERS .............. ZONE X Areas of 0.2% annual chance flood; areas of 1% annual chance flood Plane north zone (FIPSZONE 0501).The horizontal datum was NAD83, . .. . . .. . . .. . . .. . with average depths of less than 1 foot or with drainage areas less than ............. GRS1980 spheroid. Differences in datum, spheroid, projection or State Plane LARIMER COUNTY I square mile; and areas protected by levees from 1% annual chance zones used in the production of FIRMs for adjacent jurisdictions may result in G Cache La ........... flood. slight positional differences in map features across jurisdiction boundaries. . . . .. . UNINCORPORATED AREAS-, Poudre River . . . . . . . . . . . . . . : 080101 These differences do not affect the accuracy of the FIRM. ZONEAE OTHER AREAS . .. . . .. . . .. . . .. . . .. . . .. . Flood elevations on this map are referenced to the North American Vertical ZONE X Areas determined to be outside the 0.2% annual chance floodplain. Datum of 1988. These flood elevations must be compared to structure and ZONE D Areas in which flood hazards are undetermined, but possible. ground elevations referenced to the same vertical datum. For information . .. . . .. . regarding conversion between the National Geodetic Vertical Datum of 1929 1445000 FT . . . . . . . .1, N. .. .......... and the North American Vertical Datum of 1988, visit the National Geodetic ... .................. COASTAL BARRIER RESOURCES SYSTEM (CBRS) AREAS ........... CITY OF FORT COLLIN Survey website at http://www.ngs.noaa.gov/ or contact the National Geodetic xx,, .... ............ Survey at the following address: ...................... ................................... .................... �x �x ................ ................. ...... OTHERWISE PROTECTED AREAS (OPAs) 5: .............................. ..... . ...... ........ .. NGS Information Services . . . . . . . . . . . N."'.:.......... ........... ..... ;X X.N.N., ............. .......................... .. ....... ...... .......... ....... ..... CBRS areas and OPAs are normally located within or adjacent to Special Flood Hazard Areas. ................................ ................ ................................................... NOAA, N/NGS12 :N . ........ ........ :X, National Geodetic Survey DRAKE ROAD) ..................... ...... ................................. Floodplain boundary ............ .......... .... ......... .......... ................. W :AL SSMC-3, #9202 > DRIVE Floodway boundary ................ ....................... .............................. ............. ............... 1315 East-West Highway ....... ........... DRIVE Zone D boundary ..............--------------- C Silver Spring, MD 20910-3282 44 000M 89 N ............ ........-.1'..". .. ................ ............................ CBRS and OPA boundary ..........I, Ila ......................... To obtain current elevation, description, and/or location information for bench marks 0 �b-`,�] ................. AV Boundary dividing Special Flood Hazard Areas of different ............................... shown on this map, please contact the Information Services Branch of the ................ . ..... K:K:: :i:K] x. Base Flood Elevations, flood depths or flood velocities. National Geodetic Survey at (301) 713-3242, or visit its website at 0 LIMON DRIVE .. . .. ... .. ................... ............... V. ............. W http://www.ngs.noaa.gov/. ... ...... 0 513 Base Flood Elevation line and value; elevation in feet* XXXXXX. X (EL 987) Base Flood Elevation value where uniform within zone; Base map information on this FIRM was provided by the Larimer County GIS and Cc ....... ........ .... 'XIN-XI: NX.N.: ....... ..... < . ............ .......... elevation in feet* Mapping Department. Additional input was provided by the City of Fort Collins LL0490 Geographic Information Services Division. These data are current as of 2010. Referenced to the North American Vertical Datum of 1988 (NAVD 88) Cc ............. ....... Cross section line )7 Z W ......... This map reflects more detailed and up-to-date stream channel configurations than those shown on the previous FIRM for this jurisdiction. The floodplains Transect line ............................. ................. .............................. ......... ....................... .......... and floodways that were transferred from the previous FIRM may have been Geographic coordinates referenced to the North American .......... '22'30" 97TT30",32 adjusted to conform to these new stream channel configurations. As a ............. Datum of 1983 (NAD 83) .............. ........ ............................ . ....................................................... ... ... result, the Flood Profiles and Floodway Data tables in the Flood Insurance 42 ........... ... ..... ... 75000mN 1000-meter Universal Transverse Mercator grid ticks,zone 13 Study report (which contains authoritative hydraulic data) may reflect stream ............................. .............. channel distances that differ from what is shown on this map. X ........................ .....................X. ................. ..................... 5000-foot grid ticks: Colorado State Plane coordinate ........... -,: :::;::: 6000000 FT ............*.............. x......, system,north zone(FIPSZONE 0501),Lambert Conformal Conic ................................ ...... ..................... :::::::...-X X Corporate limits shown on this map are based on the best data available JOSEPH DR. .. . . .... . CD In .......... at the time of publication. Because changes due to annexations or de-annexations 0 0 .................. ........ 0 als may have occurred after this map was published, map users should contact X.: Bench mark (see explanation in Notes to Users section of DX551 0 _J ...... ........................... _J appropriate community officials to verify current corporate limit locations. Lu "................... X % this FIRM panel) Z Z ........... 9 M1.5 .91 .......... Please refer to the separately printed Map Index for an overview map of the ..... .... River Mile N .......................... ................................................ < U) county showing the layout of map panels;community map repository addresses; U) M �,FLINGER DRIVE o . ....... x X. 0 ..... Z Z LLI MAP REPOSITORIES ................. ................ 0 and a Listing of Communities table containing National Flood Insurance Program ...................... ... .... ...... . ...........X ......... Refer to Map Repositories list on Map Index 0 ., . .I... ., x.- ..........................::,:,:. :,:. :1:1:1: dates for each community as well as a listing of the panels on which each Z 0 ................................................ ............ ........... ...... .. ............ < ...x.: X.: community is located. <n ............ ............. Cc M ........ xxx EFFECTIVE DATE OF COUNTYWIDE CIO, PARKWAY ..................... FLOOD INSURANCE RATE MAP ........ .... .. ............... ................................. .... . . ..... For information and questions about this map, available products associated with this 1 INN 1: 1 .... December 19,2006 .... .. . ... .................... ... ....... .............. ........................... FIRM including historic versions of this FIRM, how to order products or the National . ............. EFFECTIVE DATE(S)OF REVISION(S)TO THIS PANEL 29 . ..... ............................................... Flood Insurance Program in general, please call the FEMA Map Information eXchange May 2,2012—to change Special Flood Hazard Areas, to change floodway, to reflect updated 00 0) .. ......... . ....... .. N.'N'................ 3J .... ....... ........... topographic information, to change Base Flood Elevations,and to incorporate previously issued at 1-877-FEMA-MAP (1-,877-336-2627) or visit the FEMA Map Service Center website BANK DRIVE .................... Letters of Map Revision. .......... at http://msc.fema.gov.Available products may include previously issued Letters of Map SLADE STREETI ..... ...... ....... ................... m < X......... ............... A�tA UHiVp C; ................................................................. .................. ....... Change, a Flood Insurance Study Report, and/or digital versions of this map. Many of ........................................................... ........ .... 0 . ................................... Ak :,.. ....... .... .......... these products can be ordered or obtained directly from the website. Usersmay ................................ ............. ........................... .................................................. ......... .................. determine the current map date for each FIRM panel by visiting the FEMA Map RED CLOUD COURT F- .......... . ............. ................ Z ................................................... . ................ . .............. .............. Service Center website or by calling the FEMA Map Information eXchange. 0 ............................... . ... .......X ................................ . ............. For community map revision history prior to countywide mapping,refer to the Community .......... .................... -X, -X, 0 ................. .. .... ... .. . .. . . .......... GO ............. Map History table located in the Flood Insurance Study report for this jurisdiction. . ....... ....................... .... ........ ......... .. ......... .... . .............. ......................... ................... ............... .................. .............................. . .......... RED MO ....... .....:-: - . . . . . - . ........... .... ................... .................................... .............................. ....... .............. ............... MAROON Cotjg;, ................. ........ To determine if flood insurance is available in this community, contact your insurance ................................ .................. ... ........... ... .... ------------------------- agent or call the National Flood Insurance Program at 1-800-638-6620. Accredited Levee Notes to Users: Check with your local community to obtain ............ ........... .... ..... ..... ........ .......................... . ;::: ............ ...................................... ................................... 44 000m more information, such as the estimated level of protection provided (which may COUP'. Z N ................. ............... ..................... exceed the I-percent-annual-chance level) and Emergency Action Plan, on the Fossil Creek Reservoir Inlet Canal .. ...................................... ........................ .................. ...................................... ..................... xx., .... . .. ................... . . ....... ... .... ............... .............. ............... ............... levee system(s) shown as providing protection for areas on this panel. To 0 ............................... ................. ............. ............. Ak ...... mitigate flood risk in residual risk areas, property owners and residents are noivr: 0 .....X .............. ................ ........... .... .................... MAP SCALE I" = 500' encouraged to consider flood insurance and floodproofing or other protective . ........ ........... .............. ................ .. . ...... 250 0 500 .- :.:.. .. 4 < 863 '00IREET 0 measures. For more information on flood insurance, interested parties should EE ... .............................................. ...... A METERS ON El visit the FEMA Website at http://www.fema.gov/business/nfip/index.shtm. 150 0 150 300 ........... ....... ........ ......... . ........ ............................................................ LSTONE COURT 3e\NE ......... ............ ......................... W ..................... .......... ............ M _J .............................. ........................................... ... (D .... ............... .......... X. .................. ........... . : *I.X,.:..x---- "", ..... PANEL 0992G _.x ., --N,..,:..--:-,:..-:-,:., - .................................................................................... . .........: ........ ........ ... ....... ......... ....... N ............... ........................ ............ ................ ......... ......... ............. ... . ........ ..... .......... xx . ... ..................... 1440000 FT .......... ............. x, .................................. ................... 1, X :.: '. --:.- :.: :: - : ................ �_DSTO C .......... .................. 0 ..... ............. ................... .... DRiVE ........... ...... ....... ..... ............... X ................. ......................... ...... . ........... FIRM .................. .......... ................ ........ ............................. ... ........................ . .... FLOOD INSURANCE RATE MAP > ................................. . ... ...... ... ................. .............. ...................................... ........................... .... E Z DR X E COURT BL 0 LARIMER COUNTY, ........................... ......... 5_9 ...... ........ ............ ........................... < ........................... ............ ............. ............................................. U) HORSETOO'1111 ROAD AND INCORPORATED AREAS '4858 Ld .. ............. > ANTELOPE .. . ......... nuAu .. ........ X LLI > 61 ........... PANEL 992 OF 1420 . .. . . .. . . .. . . .. . . .. . . .. . ........... 0 (SEE MAP INDEX FOR FIRM PANEL LAYOUT) CONTAINS: .......... CO 4t 34 ,P,jeCOURT COMMUNITY NUMBER PANEL SUFFIX ............. NOTE: MAP AREA SHOWN ON THIS PANEL IS LOCATED 4 MICHELLE LANE ................. LARIMER COUNTY 080101 0992 G WITHIN TOWNSHIP 7 NORTH, RANGE 68 WEST. ............... FORT COLLINS.CITY OF 080102 0992 G ............ 0 .. . ..... . ..... > .......... 0 ............... BISON '.*.............. 32 URY < 33 DRI 0 CHARLIE LLLLJJ ............. ...... . ................ .......... .. *1*1 *1-. ": ............. 0/, .............................. ... ..... .............. ............................... ............. -A ........................... ... . LARIMER COUNTY ......... j:� 44 000m .............. ......... IN WHITWORTH DRIVE 0 DRIVE LL F__ — . .. 1.1. . . .............. .......... . ... Z UNINCORPORATED AREAS :M:-: ......... W CITY OF FORT COLLINS . ..... ........... :X:. .............. .................... .......... ...... CITY OF FORT COLLINS .. ............... .. ....... ...................... 080101 .......... ............ ......... ............... .. .... 080102 080102 DRIVE MESA VERDE Notice to User: The Map Number shown below should be ........................... used when placing map orders; the Community Number shown ............................................ ........... X < ........ .... 0 above should be used on insurance applications for the subject ........... > .................................... ............ . ....................... Z unity. ............. ........... Comm Z ............... ... . ....... . ..... ...... ..... 0 ... . ...... ..... ......... ...... ........ ........................... 091VE ...................... ..... . .. VAR1,1i ........ .... MAP NUMBER .... .. ...... -x.. ............ . .............. .......................... CAN .................. Zi SU TO .. ..... ...... 08069CO992G .......... .... .. ...................................................... 40131'52.5" L_ PA DINGTON ROAD .......... 40131'52.5" MAP REVISED JOINS PANEL 0994 105100'00.0" 105'01'52.5" 4 98000m E 499uuuffl E IVD S MAY 2, 2012 Federal Emergency Management Agency rrtabolhns Fort Collins Risk Map r 1 L -�3 Lc-,-l-u nJ 3 Legend ❑ Growth Management Area ; City Limits 0 � Percent Annual Chance Grids OILFes:No J •� tr >2%-4% >4%-10% q Citations IL r U W ' *s�Fi `i ton Rides �**� i f kI',ersedO1PEh 4 4 } 1: 18,056 Toptrrnnaw � � *, Notes Natural 0.6 0 0.28 0.6 Miles This map is a user generated static output from the City of Fort Collins FCMaps Internet mapping site and is for reference only.Data layers that appear on this WGS_1984_Web_Mercator_Auxiliary_Sphere map may or may not be accurate,current,or otherwise reliable. City of Fort Collins-GIS FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards(Ch. 5) 4.0 SWMM 4.0 SWMM This section is for project sites that require the use of the Stormwater Management Model (SWMM) to determine storm hydrograph routing and is the only method that is able to assess the overall performance of multiple detention basins in parallel or in series in a particular project site or watershed. Reference: The theory and methodology for reservoir routing is not covered in this Manual as this subject is well described in many hydrology reference books. The EPA SWMM Reference Manuals, dated January 2016, have been utilized in preparing the information in this section of the Manual. 4.1 Input Parameters Table 4.1-1 provides required input values to be used for SWMM modeling. Basin and conveyance element parameters must be computed based on the physical characteristics of the site. Table 4.1-1. SWMM Input Parameters Depth of Storage Impervious Areas 0.1 inches Pervious Areas 0.3 inches Infiltration Parameters Maximum 0.51 in/hr Minimum 0.50 in/hr 0.0018 in/sec or Decay Rate 6.48 in/hr Zero Detention Depth 1% Manning's"n" Pervious Surfaces 0.250 Impervious Surfaces 0.016 For Overall Drainage Plan (ODP) and Project Development Plan (PDP) submittals, when surface types may not yet be known, land uses may be used to estimate impervious percentages. Table 4.1-2 lists the percent imperviousness for common types of land uses in the City. City of 4.1 Input Parameters FN t-Collins Page 10 FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards(Ch. 5) 4.0 SWMM Table 4.1-2. Land Use-Percent Impervious Percent Impervious Land Use N Residential Urban Estate 30 Low Density 50 Medium Density 70 High Density 90 Commercial Commercial 80 Industrial 90 Undeveloped Open Lands,Transition 20 Greenbelts,Agriculture 2 Offsite Flow Analysis(when Land Use not defined) 45 Reference: For further guidance regarding zoning classifications, refer to the Land Use Code, Article 4. For Final Plan (FP) submittals, impervious values must be based on the proposed land surface types. Refer to Table 4.1-3 for recommended percent impervious values. Table 4.1-3.Surface Type—Percent Impervious Percent Impervious Surface Type N Hardscape or Hard Surface Asphalt, Concrete 100 Rooftop 90 Recycled Asphalt 80 Gravel 40 Pavers 40 Landscape or Pervious Surface Playgrounds 25 Lawns, Sandy soil 2 Lawns, Clayey soil 2 City of 4.1 Input Parameters F6rt, Collins Page 11 FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards(Ch. 5) 4.0 SWMM The composite imperviousness is obtained using the following formula: n I(I;xAj I= `-i A Equation 5-6 Where: I = Composite Imperviousness, Ii = Imperviousness for Specific Area (A), Ai =Area of Surface with Imperviousness of I;, acres or square feet n = Number of different surfaces to be considered At=Total Area over which I is applicable, acres or square feet 4.1.1 Intensity-Duration-Frequency Curves for SWMM The hyetograph input option must be selected when creating SWMM input files. Hyetographs for the 2- year, 5-year, 10-year, 25-year, 50-year, and 100-year Fort Collins rainfall events are provided in Table 4.1-4. Table 4.1-4. IDF Table for SWMM Intensity Intensity Intensity Intensity Intensity Intensity Duration 2-year 5-year 10-year 25-year 50-year 100-year min in/hr in/hr in/hr in/hr in/hr in/hr 5 0.29 0.40 0.49 0.63 0.79 1.00 10 0.33 0.45 0.56 0.72 0.90 1.14 15 0.38 0.53 0.65 0.84 1.05 1.33 20 0.64 0.89 1.09 1.41 1.77 2.23 25 0.81 1.13 1.39 1.80 2.25 2.84 30 1.57 2.19 2.69 3.48 4.36 5.49 35 2.85 3.97 4.87 6.30 7.90 9.95 40 1.18 1.64 2.02 2.61 3.27 4.12 45 0.71 0.99 1.21 1.57 1.97 2.48 50 0.42 0.58 0.71 0.92 1.16 1.46 55 0.35 0.49 0.60 0.77 0.97 1.22 60 0.30 0.42 0.52 0.67 0.84 1.06 65 0.20 0.28 0.39 0.62 0.79 1.00 70 0.19 0.27 0.37 0.59 0.75 0.95 75 0.18 0.25 0.35 0.56 0.72 0.91 80 0.17 0.24 0.34 0.54 0.69 0.87 85 0.17 0.23 0.32 0.52 0.66 0.84 90 0.16 0.22 0.31 0.50 0.64 0.81 95 0.15 0.21 0.30 0.48 0.62 0.78 100 0.15 0.20 0.29 0.47 0.60 0.75 105 0.14 0.19 0.28 0.45 0.58 0.73 110 0.14 0.19 0.27 0.44 0.56 0.71 115 0.13 0.18 0.26 0.42 0.54 0.69 120 0.13 0.18 0.25 0.41 0.53 0.67 City of 4.1 Input Parameters �,F�t� Collins Page 12 APPENDIX B Reference Reports r da ,[•.; ' -r-el 1 0. t• .ai. 40 d i 'f'4' I 'Y 1 , , . 1 . fi _ � .X , . Fox Meadows Basin bw Kill. Proposed BMP Basin Type son jam`' ��X '-'+ .. � �-- � , -41'�,, 1� ,,I�•� 44 k ,. - 1 i._.. •.•' A Y';-: a � _ � ,.T •.. _ �. •w s IN `r Flood Control Only . .,-�p- `- , -. - _ „•: ! '�. • r+,. '� wr a '`Fa . � � r :�_., .9�..r � �F . . - - M r .+ �' _ i - - r LN I ti , � Water Quality Only Z, ' U *' '�' : '" i ". '• c r to I 6_ i �til # y , 0% 4 — u. •� '��at -• P 4 r ~`L � _ - I. 1Iy+ , I P.n ,P E ._Y .' _ I - ., :. " •. '', F .bias,, - - t . .' Flood Control and Water Quality Ik i,. -E �I _...' ra•. �^ , �' '. 'i ti..L Y _ P'_"" - . . -� r• lF + ''�y _ - 4 Y, I. Proposed Improvements � � � � �,• �• 4 �� _; - _ d Stone Ridge Pond � p p FF ' ~� „" r� ,.: - �• ; -. ,4..:1s =; � 4 a 1. .. �..,:. �.. - FCRID Pond 4 T - �. i Fox Meadows Pond •Alternative to FCRID location (EDBD) �.. • New Pond to accommodate�. ' ! •r � ' � • Retrofit Existing Pond to accommodate • � � - '- .:_. _ - Proposed Selected Plan �4- Water Quality Volume 1+ Quality Volume Y �� _ Proposed ` 9 p [ - _ E 7_ , _ _ 41-.7 a - _ 1 _ _ = -lo Water Quality Alternatives y n I I I I . - T i ate �U �_ W S 40 a ? ^ d f' = •O of - - i �.. L �. .,aJIQ �-- � Sunstone Village Regional Pond �+� 1, �• . • a`�� - qy n d a • Retrofit Ex►stin Pond to accommodate I �� - Coll►ndale Golf Course - "' '� " Y ' ? %'. � _ . Water Quality Volume r • b �i - • Source Control BMP's i �~ �,� * ke. � ` _J, ..-fit � P' M ,s�, w� , 1� ,# J. P' _ • _.- ,c I. _ k - - J 1� - •_ �•' - _ - r n see report text t r � • �' h. .,, - ( P ) •°a � �� � I ,.f''y.'• . .. .r s.'�+„�'' : - _ - 1 - •� " P k - - - a RSET D - - :�_._- _ , . Y � ,•Y_ E HO OOTH R_ ��.. , . CO RD 40 � - I .- �` �4 � �_ E _ s• r � � - III • '! - - - ArTs raid , • _ r ,' 'F" `q I Rr 4- lip- - _ - - f0 a _ may ` . W V. -Will �# fiG<• fir* ,��+ r -'` '' "` INS "• "�` s ® _ - `fir - _ �� - ell, na ,~ '`' - i_ • ilk ', 6 : �'. �•:In ■ - 4W W 4 _ 'y 1 F IP 1 !A s- ,'4 11 .'. I- ' •'' 1 _ ' ' r co ZA 0 • _ 1 � $ Woodland Park Pond - Ac - r- : ' , „ • Retrofit Existing Pond to accommodate , ' " Water - _ r W t r Quality Volume y • 1 + ,n M v 17M i r, • r F Z t_ OL IT . - — a- - a ' r x I - • w � Pq all 4iileeleeel Arm , �I lf- IF Golden Meadow Pond -3"� s - ". leer ' r - -- "� km' <. y '� + , `,� ,i, _ Hewlitt-Packard Ponds - Retrofit Existing Pond to accommodate , ? , , r • Retrofit ExistingPond to accommodate Er Water QualityVolume L. • : � Water Quality Volume i - . ' FI. n .,...,• -'•-. � � �,, '�' I *' � ,'d � .� 'Ire -, I .t-. * _ r - � i_��+rf�' ti�,�. _ ,� ,I s- _ :. —r � _-- _ _ - I ° - W i 1 1 ..' - ' '. a ..f... -�1�,- .4 -i�, L,f1. y ,i ,. 1i • L -- - -1.- - f,: _- _ - A - - •(t'mJl- _ If ■ City of N FWFox Meadows Basin 0 500 1,000 1,500 2,000 E Feet art a ir�sr INC. Selected Plan = Water QualityImprovements S 1 inch = 500feet ENGINEERING, ti t, f ylf. v: YYi 5. r� {v r < 4 F" Addendum h to The Final Design Report 3 ' for i The Fossil Creek Reservoir Inlet Ditch E 6t 4 Storm Water Overflow ,' ` li J•. September 1988 i , f !j R y L la}j\Jr r 4 Y City of Fort Collins Storm Water Utility i . .5 t "r Donohue & Associates, Inc, tits e�i - 4730 South College Avenue zc" Fort Collins, Colorado 80525 226-2323 Project No. 272. 000 ,Y �v f r, SUMMARY The review of the "Final Design Report for the Fossil Creek Reservoir Inlet Ditch Storm Water Overflow" by the City of Fort Collins and the other affected property and ditch owners indicated several refinements to the design were desirable. 1 These design refinements include improvements in alignment, hydraulics, operations and maintenance considerations, safety and "- coordination with existing. facilities. �a> r ' The appropriate figures from the Final Design Report have been modified to reflect the revised design concept and are included 4- in this addendum. The design as outlined in this addendum will be used to prepare the construction documents and easement descriptions for this project. DESIGN REVISIONS lti The basic channel design has been modified to occupy the smallest amount of easement space possible while still meeting the City of Fort Collins criteria for major drainage channels. The channel design criteria is as follows: `` . Design flow, 100-year recurrence interval 860 CFS Maximum depth at 100-year flow 4 feet Y; Friction factor (n) 0. 04 Side Slopes 4 : 1 Maximum desirable velocity 5 FPS The channel is routed due east along the north side of County <` Road 40 . The south side of the channel is 34 feet from the south section line of Section 28 which is the centerline of County Road 4 40. The existing right-of-way (ROW) for County Road 40 is 30 feet either side of the section line. The additional four feet .' of setback is for the anticipated ROW required for the City of <<` Fort Collins standard 'collector street which will be constructed , in the future when the area is annexed. The channel parallels County Road 40 to the east side of County Road 7 where it turns south across the County Road 40 ROW making a smooth confluence with the Poudre River. The basic channel ROW requirements are an 80-foot wide ROW west of the Box Elder Ditch and a 100-foot ROW east of the Box Elder Ditch. The channel alignment utilizes a minimum of private property and county road ROW. x A seven percent grade section of channel in the first reach (Sta. 0+00 to Sta. 1+00 will cause a hydraulic um to occur in the ) Y jump channel at approximately Sta. 0+80. The hydraulic jump will be weak and submerged under most conditions. Riprap channel protection will be provided from Sta. 0+00 to Sta. 1+20 to insure ' Y. E s' ,y��.. , . a•. -.-,_. ... .._ ,. :.-,:_. ,, ., r.. �. ♦ .;:-Y � 1 '_I V J'.r 945, � P ',l+,x :-;. >P,xM•pt�y"+•S R+r.a...:it _ ..:. , - > '-. _ , 'SG,.: ...,'.r .:r .' � � 3 :. yy-.,+1 r 1:.• ..rr '� �.`.i +'i 2 - .. m:.. '-, � .. f. dd�.. -.. 1•.�-, TI r. ..: y:."�,.: `. ,;c; 'i�. J a�}?:is �'t�- :�:e-3 rr�„i.•dr !+ .>:� .s — -Mr- �.ZR Y„�4:-.. 4`[ i - -.� � -.-�: ."f.- � .._.ram ., -.• t f '1.s .1 �'/>< _ .-:i.. � _ - - _� r ., � •P... lr ..�a:, ''1Fj-;.•r.,a' _..rye�•s Sy„ x 1 , �..r`fir .:- , .< _ ,::•..: E-.:',: 4_..z_+,:, .,=P. .. :k.r _ '. CA lk Im-ma 'R'i'..+:.,.�at,Yc.s•'�c;reset»`i�M �w`k�...f,4s�',mr.,.,- O - },a ,;y�.� ..::,..Y. .� .:�`'���'�raY,ii,:...^� -+'.:�, s..-. :_.. _ .>a....,i,o ss. .so._ ..n Y...�51�7,.a:.a.•r ��.+.� + - IMIL r_ . `�`.� z • • 1 1 1 zYq • • • �+ 11 5. It •i • ! • • ,u '? OItsm l C WAM . i 1I ■, • 1 S' *. Q Ads / / 1 II / / i / : 11 / II li / 1 / 1 . / / 40 11 it ! / �` '1. !. .h t- 'era' •,St`o�°t- ,-.�.__...,....,!k5ra.ii...1.r..-..-.k...>'.2,d.K.,,..�.:4_u.._.%�,,..r°�E..k.•�€S._a_�.i��:s:.,,._v..:... ��e<v_S:,_�.$:.�"��3_-tru'._�...t'."�_"':�.e....,x:t<;rae.Ey_i<•___,x.....,._...-��.t,. i„_s-,ssx�.e__z,1_.m�s:....•zr< ,+.._,>_._�Sssa,'3:.R-.tx...,_.�,.:¢o,,,.�rt<�>ti+�.?�_., :_vY.xL..r,-._�.rr_.�::�4s'E-...'. -. ,m�'.s3�:: , :-�°+`: { .rr .>_�.. < ,,.'h.,4,,:.,..d_:a.,,,.. �.,^$._L�4 .'_�1� �«_a•.x _ .-.. .__,:-� MEMORANDUM N ANdtit5uN CUNSUIHNy EMIiNWO, 1011- 001 - ff&,P—Resowves • Fnr+i+o n e nlal DATE: April 30, 2020 ACE PROJECT NO.: COCLF11 TO: Bill McDowell, Manger, Cottonwood Land and Farms FROM: Brian Smith, Anderson Consulting Engineers, Inc. Brad Anderson, Anderson Consulting Engineers, Inc. Mike Turner, Anderson Consulting Engineers, Inc. SUBJECT: Hydraulic Analysis of Fossil Creek Reservoir Inlet Ditch (FCRID) Between Cache la Poudre River and Harmony Road for Future Strauss Lake Development BACKGROUND INFORMATION AND PREVIOUS STUDIES: In 2001 and 2002, Anderson Consulting Engineers, Inc. (ACE) completed a hydrologic and hydraulic evaluation of the Fossil Creek Reservoir Inlet Ditch (FCRID) for Cottonwood Land and Farms. The purpose of this study was two-fold: (1) assess flooding potential along the ditch from large magnitude storms that enter the ditch from the Cache la Poudre River (Poudre River), the Foothills Regional Channel, and local runoff from adjacent neighborhoods; and (2) investigate options for controlling the flooding potential as it pertains to Cottonwood Land and Farms' future development site (Strauss Lake Development) east of the ditch. Recommendations from the 2002 study resulted in the sizing and construction of a bridge/culvert over the ditch at William Neal Parkway, which is located directly to the west of the existing concrete batch plant. An orifice plate was installed on the upstream side of the William Neal Parkway crossing to check flows in excess of the maximum irrigation flow to facilitate the diversion of excess stormwater from the ditch. The 2002 study conceptually envisioned that a lateral overtopping spill structure would be created to spill excess stormwater from the ditch that is being checked by the orifice plate. The lateral overtopping spill would be created by the lowering of the eastern bank of the ditch between the William Neal Parkway crossing and the upstream Environmental Drive road crossing. It is noted that the lowering of the eastern bank of the ditch and installation of this overtopping spillway has yet to be constructed. A vicinity map of FCRID, William Neal Parkway, the conceptual lateral overtopping spill location from the 2002 study, and the study reach evaluated for this study is illustrated in Figure 1. In 2017 and 2018,ACE conducted a calibration study of FCRID between Horsetooth Road and the Great Western Railroad (GWR)for the City of Fort Collins Utilities Department. The purpose of this study was to develop a depth/discharge rating curve of the ditch at the upstream side of the Environmental Drive Bridge crossing that would allow the City and the North Poudre Irrigation Company to estimate the discharge in the ditch based on a water depth reading from a staff gage. Results of this study indicated that the development of a rating curve was possible, but that the rating curve could shift dramatically based on downstream tailwater conditions and roughness values of the ditch. This study also concluded that under current ditch conditions,the maximum flow rate that can be conveyed within the ditch prior to flow spilling over the lateral weir structure upstream of Horsetooth Road is approximately 120 cfs. This maximum irrigation flow rate,and the roughness values determined as part of the calibration study, were utilized as part of this study. It was also realized as part of the 2017/2018 study that the eastern bank of the ditch, upstream of the GWR, was lowered in the early 1990s to create an emergency overflow weir as part of the City's flood control project for the adjacent wastewater treatment plant. The location of the existing low bank/overflow weir is also illustrated on Figure 1. It is noted that the presence of this overflow weir was not incorporated into ACE's 2002 hydraulic evaluation of FCRID. FCRID Hydraulic Evaluation Memo.docx Page 1 of 8 April 30,2020 MEMORANDUM Alydti(suly CuNsuhhty Bgilvttl(Sr bu. Civil Water Resources Environmental z pit - ,i . .� Upatraam Study Umlt � 1 -• COFC Wastewater R` Treatment Plant O Existing Low [ T. BenklOverHow •' Weir Location ,a.. J Conceptual Lateral ' I Spill Location From ®® ?ena amrty SxK 1 Futwr� William Nodi Pkayr Park � i Site I u Orifico Plate L CQSlOi1WPOd Fossil Crook Farms Ditch(FCRID) �' t Horsatoolh Rd Radial Gate � ' �' a k Snlll Lne�tlon E 1 �, _c �, to Ail ur' — l _ �i iG 1 1 Downatraam Study Limlt .. liarrn,4iq Rd - — - _��• tl 750 1,500 9,000 f a f� ` Feet A Figure 1.Vicinity Map. FCRID Hydraulic Evaluation Memo.docx Page 2 of 8 April 30,2020 ��`lJ p •. �,r CUt1U �.ti li]f�LnN FiSi.�AS.'J +�,� 4�2�. Z. 'S, trr (+ i �'N' d, '•�►Y� O Z 16 - � (rI� a �..w•✓tr _j U jag u) � ,� �• searQ+i r .si .a''" ,,tip'^ # rr �1�.� 4 d /'�pA,.,:: �•1 � ,� �j 'fir r!° d'xsy-..th�/ �°:'`«.r�� ��,r��. •�' ���¢J� 3 LL �+. w;s Y 1 F FEB 2 5 ?Ate alMd Repo ate 5IZCI) �Z FINAL DRAINAGE AND EROSION CONTROL REPORT Rigden Farm - Filing Six Prepared for: Rigden Farm LLC c/o Wheeler Commercial 1'027 W. Horsetooth Road, Suite 200 Fort Collins, Colorado 80526 (970) 225-9305 Prepared by; JR Engineering 2620 E. Prospect Road, Suite 190 Fort Collins, Colorado 80525 (970) 491-9888 - ; Revised February 8, 2002 Revised December.5, 2001 Revised July 25, 2001 Revised March 28,2001 December 13, 2000 Job Number 9164.12 Swale to Poudre River Worksheet for Trapezoidal Channel Project Description Project File x:\3910000.all\3916412\drainage\filing6.fm2 Worksheet Swale to Poudre River Flow Element Trapezoidal Channel Method Manning's Formula Solve For Channel Depth Input Data Mannings Coefficient 0.035 Channel Slope 0.003000 ft/ft Left Side Slope 4.000000 H : V Right Side Slope 4.000000 H : V Bottom Width 15.00 ft Discharge 134.00 cfs Results Depth 1.97 ft Flow Area 45.12 ft2 Wetted Perimeter 31.26 ft Top Width 30.77 ft Critical Depth 1.21 ft Critical Slope 0,018313 ft/ft Velocity 2.97 ft/s Velocity Head 0.14 ft Specific Energy 2.11 ft Froude Number 0.43 Flow is subcritical. Notes: Q = ASINWQ100 from SWMM 9164-PRO.out CE 9�ZV--, 03/24/01 FlowMaster v5.15 03:56:27 PM Haestad Methods, Inc. 37 Brookside Road Waterbury,CT 06708 (203)755-1666 Page 1 of 1 Swale to Poudre River Cross Section for Trapezoidal Channel Project Description Project File x:13910000.all\3916412\drainage\filing6.fm2 Worksheet Swale to Poudre River Flow Element Trapezoidal Channel Method Manning's Formula Solve For Channel Depth Section Data Mannings Coefficient 0.035 Channel Slope 0.003000 ft/ft Depth 1.97 ft Left Side Slope 4.000000 H : V Right Side Slope 4.000000 H : V Bottom Width 15.00 ft Discharge 134.00 cfs — too 1.97 ft 1 15.00 ft V H 1 NITS 03/24/01 FlowMaster v5.15 03.56:32 PM Haestad Methods, Inc. 37 Brookside Road Waterbury,CT 06708 (203)755-1666 Page 1 of 1 Swale to Poudre River Worksheet for Trapezoidal Channel Project Description Project File x:\3910000.all\3916412\drainage\filing6.fm2 Worksheet Swale to Poudre River Flow Element Trapezoidal Channel Method Manning's Formula Solve For Channel Depth Input Data Mannings Coefficient 0.035 Channel Slope 0,003000 ft/ft Left Side Slope 4.000000 H : V Right Side Slope 4.000000 H : V Bottom Width 15.00 ft Discharge 178.00 cfs CC> Q�dO (!�L[C \ Results Depth 2.29 ft Flow Area 55.24 ftz Wetted Perimeter 33.86 ft Top Width 33.30 ft Critical Depth 1.43 ft Critical Slope 0.017490 ft/ft Velocity 3.22 ft/s Velocity Head 0.16 ft Specific Energy 2.45 ft Froude Number 0.44 Flow is subcritical. Notes: Q = 133% of Q100 from SWMM 9164-PRO.out CEW Z1.�, 03/24/01 FloWMaster v5.15 03.52:53 PM Haestad Methods, Inc. 37 Brookside Road Waterbury,CT 06708 (203)755-1666 Page 1 of 1 Swale to Poudre River Cross Section for Trapezoidal Channel Project Description Project File x:13910000.all\3916412\drainage\filing6.fm2 Worksheet Swale to Poudre River Flow Element Trapezoidal Channel Method Manning's Formula Solve For Channel Depth Section Data Mannings Coefficient 0,035 Channel Slope 0.003000 ft/ft Depth 2.29 ft Left Side Slope 4.000000 H : V Right Side Slope 4.000000 H : V _ Bottom Width 15.00 ft // � Discharge 178.00 cfs — i3��lp (op C�'Y{C,FS 2.29 ft 1 15.00 ft V H 1 NTS 03/24/01 FlowMaster v5.15 03'53:16 PM Haestad Methods, Inc. 37 Brookside Road Waterbury,CT 06708 (203)755-1686 Page 1 of 1 APPENDIX C Hydrologic & Hydraulic Computations Rational Method Calculations Horsetooth Road Existing Conditions Prepared By: RJJ Project: Strauss Lakes Date: 07/26/24 Basin Description: East Horsetooth Road NRCS Hydrologic Soil Rating: D Basin Area= 5.61 [acres]= 244,291 [sf] Surface Characteristics' Sub-Area Imp Runoff [acres] [%] Coefficients' asphalt,concrete 0.30 100.0 0.20 gravel 1.63 40.00 0.50 lawns,clayey soil,avg slope 2-7% 3.69 2.00 0.25 1 City of Fort Collins"Stormwater Criteria Manual",Table 3.2-2 Weighted Percent Imperviousness: I [%]= 18.29 A,= 44,669.11 [sf] Composite Runoff Coefficients: C= 0.32 Frequency Adjustment Factors(C,)z: 2-Year Cf= 1.00 10-Year Cf= 1.00 100-Year Cf= 1.25 Cz= 0.32 C10= 0.32 C1002 = 0.40 z City of Fort Collins"Stormwater Criteria Manual",Table 3.2-3 Time of Concentration: Overland Flow Time: Channelized Flow Time: L;[ft]= 42 Lt1[FT]= 1860 Lt2[FT]= 0 Si[%]= 0.10 St1[%]= 0.01 Ste[%]= 0.00 t;[min]= 20.13 Vt1[fps]= 3.20 V12[fps]= 0.00 tt1[min]= 9.69 tt2[min]= 0.00 tt[min]= 9.69 Time of Concentration: t,=t;+tt[min]= 29.82 t,(minimum)= 5 min t,[min] Rainfall Intensity3 IZ[in/hr]= 1.30 110[in/hr]= 2.21 1100[in/hr]= 4.52 3 City of Fort Collins"Stormwater Criteria Manual"Table 3.4-1 Runoff-Rational Method Equation Q2[cfs]= 2.34 Q10[cfs]= 3.97 Q100[cfs]= 10.16 °City of Fort Collins"Stormwater Criteria Manual",Equation 5-1 4 �� J:\Cottonwood Land-372\372.001.01 Strauss Lakes\Memos&Reports\Drainage\Spreadsheets\Rational Method Calcs.xlsx C I V I L R L s w R c_L 5 Historic $WMM Model d l All. � � . . - Z®2 �\ - � \? \ K }— � . � SWMM 5.2 Page 1 Historic SWMM Model Subcatchment Runoff Summary Total Total Total Total Impery Precip Runon Evap Infil Runoff Subcatchment in in in in in WestSite 0.98 0.00 0.00 0.94 0.02 EastSite 0.98 0.00 0.00 0.96 0.02 SWMM 5.2 Page 1 Historic SWMM Model Subcatchment Runoff Summary Pery Total Total Peak Runoff Runoff Runoff Runoff Runoff Subcatchment in in 10^6 gal CFS Coeff WestSite 0.02 0.04 0.01 0.90 0.036 EastSite 0.00 0.02 0.05 4.92 0.018 SWMM 5.2 Page 2 Preliminary Proposed $WMM Model ��> . �� � . . \Z - 3» � �§ . - ,� ,\ » : SWMM 5.2 Page Preliminary Proposed SWMM Model Subcatchment Runoff Summary Total Total Total Total Impery Precip Runon Evap Infil Runoff Subcatchment in in in in in E-1 3.69 0.00 0.00 0.15 3.24 E-2 3.69 0.00 0.00 0.15 3.24 E-3 3.69 0.00 0.00 0.15 3.24 E-4 3.69 0.00 0.00 0.15 3.24 E-5 3.69 0.00 0.00 0.15 3.24 SWMM 5.2 Page 1 Preliminary Proposed SWMM Model Subcatchment Runoff Summary Pery Total Total Peak Runoff Runoff Runoff Runoff Runoff Subcatchment in in 10^6 gal CFS Coeff E-1 0.22 3.46 1.88 133.77 0.937 E-2 0.22 3.46 1.88 133.77 0.937 E-3 0.22 3.46 1.88 133.77 0937 E-4 0.22 3.46 1.88 133.77 0.937 E-5 0.22 3.46 1.88 133.77 0.937 SWMM 5.2 Page 2 Preliminary Proposed SWMM Model Storage Volume Summary Average Average Evaporation Exfiltration Maximum Storage Volume Percent Loss Loss Volume Unit 1000 ft3 Full % % 1000 ft3 CWP 229.665 46.6 0.0 0.0 469.407 SWMM 5.2 Page 1 Preliminary Proposed SWMM Model Storage Volume Summary Maximum Day of Hour of Maximum Storage Percent Maximum Maximum Outflow Unit Full Volume Volume CFS CWP 95.3 0 01:35 129.20 SWMM 5.2 Page 2 WQCV Calculations EAST SITE Area 99.10 acres a' 0.90 (24 hours, CWP) Imperviousness 0.90 %as decimal WQCV 0.36 wat-in WQCV 3.58 ac-ft 155984 ft WEST SITE Area 12.08 acres a' 1.00 (40 hours,WQCV Pond) Imperviousness 0.90 % as decimal WQCV 0.40 wat-in WQCV 0.485 ac-ft 21127 ft HORSETOOTH ROAD Area 5.61 acres a' 1.00 (40 hours, EDB) Imperviousness 0.95 % as decimal WQCV 0.45 wat-in WQCV 0.25 ac-ft 10929 ft 'Drain time coefficients from Table 5.4-1 of the FCSCM and Table 3-2 of the USDCM. Constructed Wetland Pond Permanent Pool Cv' 0.75 WQCV 3.58 ac-ft VP2 2.69 ac-ft 116988 W 'Sizing coefficient from MHFD Fact Sheet T-7. 2Equation RP/CWP-1 from MHFD Fact Sheet T-7. FAA Detention Sizing Major Design Storm: 100-year West Site Area 12.08 AC 526205 SF Impervious 90% 'Runoff Coefficient 0.85 QouT 0.90 US Storm Duration Rainfall Intensity Inflow Volume Outflow Volume Storage Volume T 2/ 3V 4Vo 5vs (min) (in/hr) ft3 ft3 ft3 5 9.95 30650 270 30380 10 7.72 47561 540 47021 15 6.52 60253 810 59443 20 5.60 69001 1080 67921 25 4.98 76702 1350 75352 30 4.52 83540 1620 81920 35 4.08 87976 1890 86086 40 3.74 92166 2160 90006 45 3.46 95924 2430 93494 50 3.23 99497 2700 96797 55 3.03 102670 2970 99700 60 2.86 105719 3240 102479 65 2.71 108522 3510 105012 70 2.59 111695 3780 107915 75 2.48 114591 4050 110541 80 2.38 117302 4320 112982 85 2.29 119920 4590 115330 90 2.21 122538 4860 117678 95 2.13 124664 5130 119534 100 2.06 126912 5400 121512 105 2.00 129377 5670 123707 110 1.94 131471 5940 125531 115 1.88 133196 6210 126986 120 1.84 136030 6480 129550 Modified FAA Storage Volume 129550 ft3 Modified FAA Storage Volume 2.97 ac-ft 'Runoff coefficient from table 3.2.1 in Fort Collins Stormwater Criteria Manual(FCSCM). 2Intensity from Table 3.4.1 in FCSCM. 3Calculated per equation 6-1 in FCSCM. 3Calculated per equation 6-2 in FCSCM. 3Calculated per equation 6-3 in FCSCM. FAA Detention Sizing Major Design Storm: 100-year Horsetooth Road Area 5.61 AC 244372 SF Impervious 95% 'Runoff Coefficient 0.95 QouT 2.34 US Storm Duration Rainfall Intensity Inflow Volume Outflow Volume Storage Volume T 2/ 3V' 4Vo 5vs (min) (in/hr) ft3 ft3 ft3 5 9.95 15909 702 15207 10 7.72 24686 1404 23282 15 6.52 31274 2106 29168 20 5.60 35814 2808 33006 25 4.98 39811 3510 36301 30 4.52 43361 4212 39149 35 4.08 45663 4914 40749 40 3.74 47838 5616 42222 45 3.46 49788 6318 43470 50 3.23 51643 7020 44623 55 3.03 53290 7722 45568 60 2.86 54873 8424 46449 65 2.71 56327 9126 47201 70 2.59 57974 9828 48146 75 2.48 59477 10530 48947 80 2.38 60884 11232 49652 85 2.29 62243 11934 50309 90 2.21 63602 12636 50966 95 2.13 64705 13338 51367 100 2.06 65873 14040 51833 105 2.00 67152 14742 52410 110 1.94 68239 15444 52795 115 1.88 69134 16146 52988 120 1.84 70605 16848 53757 Modified FAA Storage Volume 53757 ft3 Modified FAA Storage Volume 1.23 ac-ft 'Runoff coefficient from table 3.2.1 in Fort Collins Stormwater Criteria Manual(FCSCM). 2Intensity from Table 3.4.1 in FCSCM. 3Calculated per equation 6-1 in FCSCM. 3Calculated per equation 6-2 in FCSCM. 3Calculated per equation 6-3 in FCSCM. Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Jul 29 2024 Conveyance Swale (Basins 1) User-defined Highlighted Invert Elev (ft) = 100.00 Depth (ft) = 4.25 Slope (%) = 0.25 Q (cfs) = 133.77 N-Value = 0.053 Area (sqft) = 64.31 Velocity (ft/s) = 2.08 Calculations Wetted Perim (ft) = 35.59 Compute by: Known Q Crit Depth, Yc (ft) = 2.64 Known Q (cfs) = 133.77 Top Width (ft) = 34.50 EGL (ft) = 4.32 (Sta, El, n)-(Sta, El, n)... (0.00, 105.00)-(15.00, 102.00,0.025)-(21.00, 100.00,0.090)-(27.00, 102.00,0.090)-(42.00, 105.00,0.025) Elev (ft) Section Depth (ft) 106.00 6.00 105.00 5.00 104.00 4.00 103.00 3.00 102.00 2.00 101.00 1.00 100.00 0.00 99.00 -1.00 -5 0 5 10 15 20 25 30 35 40 45 50 Sta (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Jul 8 2024 Conveyance Swale (Basins 1-2) User-defined Highlighted Invert Elev (ft) = 100.00 Depth (ft) = 5.18 Slope (%) = 0.25 Q (cfs) = 267.54 N-Value = 0.048 Area (sqft) = 100.72 Velocity (ft/s) = 2.66 Calculations Wetted Perim (ft) = 45.08 Compute by: Known Q Crit Depth, Yc (ft) = 3.41 Known Q (cfs) = 267.54 Top Width (ft) = 43.80 EGL (ft) = 5.29 (Sta, El, n)-(Sta, El, n)... (0.00, 105.75)-(18.75, 102.00,0.025)-(24.75, 100.00,0.090)-(30.75, 102.00,0.090)-(49.50, 105.75,0.025) Elev (ft) Section Depth (ft) 106.00 6.00 Nr 105.00 5.00 104.00 4.00 103.00 3.00 102.00 2.00 101.00 1.00 100.00 0.00 99.00 -1.00 -5 0 5 10 15 20 25 30 35 40 45 50 55 Sta (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Jul 8 2024 Conveyance Swale (Basins 1-3) User-defined Highlighted Invert Elev (ft) = 100.00 Depth (ft) = 5.83 Slope (%) = 0.25 Q (cfs) = 401.31 N-Value = 0.045 Area (sqft) = 131.31 Velocity (ft/s) = 3.06 Calculations Wetted Perim (ft) = 51.71 Compute by: Known Q Crit Depth, Yc (ft) = 3.94 Known Q (cfs) = 401.31 Top Width (ft) = 50.30 EGL (ft) = 5.98 (Sta, El, n)-(Sta, El, n)... (0.00, 106.50)-(22.50, 102.00,0.025)-(28.50, 100.00,0.090)-(34.50, 102.00,0.090)-(57.00, 106.50,0.025) Elev (ft) Section Depth (ft) 107.00 7.00 106.00 6.00 105.00 5.00 104.00 4.00 103.00 3.00 102.00 2.00 101.00 1.00 100.00 0.00 99.00 -1.00 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 Sta (ft) Channel Report Hydraflow Express Extension for Autodesk®Civil 3D®by Autodesk, Inc. Monday,Jul 29 2024 Conveyance Swale (Basins 1-4) User-defined Highlighted Invert Elev (ft) = 100.00 Depth (ft) = 6.34 Slope (%) = 0.25 Q (cfs) = 535.08 N-Value = 0.043 Area (sqft) = 158.26 Velocity (ft/s) = 3.38 Calculations Wetted Perim (ft) = 56.91 Compute by: Known Q Crit Depth, Yc (ft) = 4.37 Known Q (cfs) = 535.08 Top Width (ft) = 55.40 EGL (ft) = 6.52 (Sta, El, n)-(Sta, El, n)... (0.00, 107.00)-(25.00, 102.00,0.025)-(31.00, 100.00,0.090)-(37.00, 102.00,0.090)-(62.00, 107.00,0.025) Elev (ft) Section Depth (ft) 108.00 8.00 107.00 7.00 106.00 6.00 105.00 5.00 104.00 4.00 103.00 3.00 102.00 2.00 101.00 1.00 100.00 0.00 99.00 -1.00 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 Sta (ft) APPENDIX D Drainage Plans LEGEND LEGEND CO NT. 7 PROPERTY LINE CHANNEL CENTERLINE CIVIL RESOURCES MAJOR CONTOUR - - - -5740- - FLOW DIRECTION MINOR CONTOUR - - -5736- SIGN 8308 COLORADO BLVD SUITE 200 BARBED WIRE FENCE k: SANITARY MANHOLE i� FIRESTONE, CO 80530 303.833.1416 CHAINLINK FENCE FLARED END SECTION WWW.CIVILRESOURCES.COM R GAS LINE STORM MANHOLE WATER LINE LIGHT POLE/UTILITY POLE , 1 �� STORM SEWER EXISTING CONTROL / J STRUCTURE FOR TREE BOXELDER D/TCH �V TELECOM % COTTONWOOD V / 4 UNDERGROUND ELECTRIC DRAINAGE BASIN BOUNDARY ■ y ® I LAND & FARMS, LLC OVERHEAD WIRES OH DRAINAGE BASIN NAME xx A xx / p BILL MCDOWELL SANITARY SEWER 2-YEAR FLOW (CFS) MANAGING PARTNER RETAINING WALL DRAINAGE AREA (ACRES) RIGDEN RESERI/OIR // PO BOX 229 50.0' DITCH BOULDER CO 80306 EASEMENT ' I � Q i - W 0 / Q U l/ // EX UTILITY` / — EASEMENT L - / / \ •_ 1 I I HORSETOOTH 5.6 I R AD AC. CFS a LL 0 i74 f D / 4875 II W OXEN p 6A,rION/ ' Ip v Q Q Q J / / / / ► EXISTING GROUNDWATER MONITORING WELL (TYP.) LLJ I V Py / Q) � / - STRUCTURE TO FCO - -- _ _ _ SITE �- � � / I �- � { REVISIONS 00.84 4.92 ' (��� � / / � /�%��1/ / / • � � _ _ Ac. cFs / � NO. DESCRIPTION DATE EXISTINC 01WRSION- / / O1 1ST REVIEW CITY COMMENTS 07/28/25 TO // ! Opp i � RIDGEN RESERviOIF / / � /� —_ . — —./ o EXISTING FCRID - , i � - � �� \� / � 11J FLOW CONTROL GATE l - - _ i ✓ i All i O0 //// �� �u - - - -- ` � � � - - - �� ' V / � v �� �K' / r SIX// L ,�_- Qti� P � _ Uj w 1 I l J 5� / �i / / _ 0 / V\ = \ _ __ _- ` DESIGNED BY: RJJ DATE: 07/11/2024 Q / / � � % ,_� FLATIRONSPOND \. - - - - - - - d _ Y ��/ / /` - _ _ �� l (�ti� ���� �� // /� / SITE � � r DRAWN BY: RJJ SCALE: 1" = 200' / - q� / — - iz.08 0.90 / / b�I CHECKED BY: JAB i � — - _ — My _ �� / �bcl , i AC. cFs 40_ y / � `{ / �� - --- --� // , / /,' / i \ o / / u H JOB NO.: 372.001.01 o 00 aoo DWG NAME:37200101HIST ODP IN FEET) o 77 - 1` HISTORIC —_- - - R ROAD =-I AD ' - �-�-�-� -- ,� _ DRAINAGE PLAN -- _ - 0 � � ' . z z RIGDEN FARM Q W SHEET: o POND 216 Know what's b@IOW. D - 1 Call before you dig. LEGEND LEGEND CO NT. PROPOSED EXISTING PROPOSED EXISTING DESIGN POINT SUMMARY PROPERTY LINE - - WATER QUALITY/ Design Point Description Q 100 (cis) FLOOD CONTROL FACILITY DP-E1 flow to swale section 1 133.77 CIVIL R E S I U R C E S MAJOR CONTOUR - - - -5740- - - - - - r r r CONVEYANCE SWALE DP-E2 flow to swale section 2 267.54 MINOR CONTOUR - - -5736- - - - - - r r r DP-E3 flow to swale section 3 401.31 8308 COLORADO BLVD SIGN DP-E4 flow to swale section 4 535.08 SUITE 200 _ BARBED WIRE FENCE ^ S DP-E5 surface flow to CWP 133.77 FIRESTONE, CO 80530 SANITARY MANHOLE / 303.833.1416 CHAINLINK FENCE DP-E6 discharge from CWP 249.51 WWW.CIVILRESOURCES.COM FLARED END SECTION DP-W1 flow to detention pond 118.88 GAS LINE STORM MANHOLE DP-W2 discharge from detention pond 0.90 4 WATER LINE W DP-H1 flow to detention pond 5.06 STORM SEWER ST LIGHT POLE/UTILITY POLE DP-H1 discharge from detention pond 2.34 EXrsTINc CONTROL J� STRUCTURE FOR / �� BOXELDER DITCH � ��// lot � �I �V TELECOM TREE - ' �J' li COTTONWOOD UNDERGROUND ELECTRIC MEN MEN! MEN DRAINAGE BASIN BOUNDARY �i ,�l LAND & FARMS, LLC Ve OVERHEAD WIRES OH DP - #A DESIGN POINT / /� % %� APPROX. LOCATION OF IIJ�I POND DISCHARGE TO FCO V SANITARY SEWER DRAINAGE BASIN NAME // / I� / / � BILL MCDOWELL / /// J ` I II " APPROX. AREA OF CONSTRUCTED MANAGING PARTNER RETAINING WALL XXX�xxx 100-YEAR FLOW (CFS) ��/ �I� WETLAND POND = 4.91 AC RIGDEN RESERVOIR // / 4 i PERMANENT POOL = 2.69 AC-FT PO BOX 229 50.0' DITCH " - / d I II WQCV = 3.58 AC-FT CHANNEL CENTER LINE DRAINAGE AREA ACRES / I. P- E6 BOULDER, CO 80306 (ACRES) EASEMENT ��j �-„ � I , III 100-YR VOL. = 7.20 AC-FT � FLOW DIRECTION TOTAL STORAGE VOL. = 10.78 AC-FT APPROX. LOCATION OF / l POND DISCHARGE TO FCO 62.0' MAXIMUM DP - E4 SWALE TOP WIDTH i /. I II Il Q100 = 535.08 CFS O DP - H2 Q 57.0' SWALE TOP WIDTH i ��/� /ll� �I I 0 /1 Q Q100 = 401.31 CFS ��_ �/ DP E3 U) J O-j w J O , - - - � O U � - - � I{III II'I'I �I APPROX. AREA OF Q U �// /�/l / .i I DETENTION POND = 0.76 AC - , T I I,.I I WQCV = 0.25 AC-FT , ^ l - J'- �_ - - 30.0' EX UTILITY I I I MODIFIED FAA STORAGE VOL. _ 49.5' SWALE / / !/ / / - - ~ �� EASEMENT I MO FLED V/ TOP WIDTH / / II I f I Q100 = 267.54�S %` J DP - E2 LL 19.90 133.77 1 I /� 1 �AC. CFS I HORSEi00TH' L.V O `J 111 ROAD 06 ITCH / ��/� J' - t 1 I 4375. - II` II Ac. cFs L.L DER IDLU N) / / 7 j I - ` l/ �II I I 'I NOTE: XE T ' BD jRRjGA � J / - � � - - - � � � -� I I � I I I LID WILL NOT BE PROVIDED FOR �� LID OR ALL OTHER DRAINAGE OOTH ROAD BASIN. 0 ~� BASINS WILL ACCOUNT FOR THE 75%LID REQUIREMENT. P E - _ - N E-4 j �� I rk`` V� i ' Q 7 19.64 133.77 V I. 42.0' MINIMUM jj/�' y _ _ ` - - i ' EAST SITE - - ( AC. CFS - I V SWALE TOP WIDTH / / �� Q100 = 133.77 CFS / / _ / NOTE. s ' J LID WILL BE PROVIDED REGIONALLY FOR THE EAST SITE VIA THE CONSTRUCTED WETLAND POND. // C?, III Q I �� / , o � E-3 EXISTING SPILL `\ I W STRUCTURE TO FCO REVISIONS _ 20�133.77 {i NO. DESCRIPTION DATE /� v / EXIST/NC D1Vf1?5ION / i / 01 1ST REVIEW CITY COMMENTS 07/28/25 STRUCTURE TO // - - - - - 1 RIDGEN RESERVOIR _ / J _ - / C _ ' - I EXISTING FCRID ' /' / J FLOW CONTROL GATE APPROX. LOCATION OF ' X I POND DISCHARGE TO FCRID E-1 _ EXISTING GROUNDWATER vl / 20.68 133.77 - _ ' \ MONITORING WELL (TYP.� AC.CFS APPROX. LOCATION OF /) // , / / / ��� A SECONDARY DETENTION POND /�\/ / / ` ,/ I l� �� / / j= (IF REQUIRED) // \ - - - / l APPROX. LOCATION OF / OJLU � l) �,' POND DISCHARGE TO FCRID 19 �P/ / / - _ - �// �� � / � ����'/ / � - 0 // - - - - - \ ' I \ ` - - / /�/ .` i �✓ WEST DESIGNED BY: RJJ DATE: 07/11/2024 GQ/ / , / \ FLA TIRONS POND \ - - _ y� / / �� l III L / elf i DP - W2 �, l SITE / ii + . / 1z.os 11s.ss/ w (� / / - _ - / j ti %/ / / %� / ._ �`��\� Ac. cFs / DRAWN BY: RJJ SCALE: 1" = 200' CHECKED BY: JAB l I � '` - / i // / \ nn ----- -{ �' � \ ��--�` % /�� / / / ��� �'� -_� NOTE: NORTH JOB NO.: 372.001.01 //G j",J- �-/� _ -� \. ',\ �\ J _ - �j- / / /9� �'� LID WILL BE PROVIDED LOCALLY r �.��Ii QCII / �^ti % / /a-/; -i_^ \. ->>T / - t _ ��=-_ -= ' / / / ��/ i �� FOR THE WEST SITE VIA RAIN I D 00 2Q0 DWG NAME:372001010DP N / / \ / / /'�lij/ / % -� ' -/ ii M--N '- -i - - �Z ET DITCH /1//� / /\ \ GRASS BUFFERS,ETC. � _- / _ �� y SERVOIR IN1- _ \ PAVERS, OSSIL CREEK R / GARDENS,PERMEABLE P S o (IRRIGATION) - -- -- - _ J /4g 1 //// _ ( IN FEET) - - F - - - __- - - - _ _ -- _ _ - - -- - -- r/ _ / J I I r �\ o - - - - - - - - - - = - - _ _ - e1q OVERALL ZIEGLERROAD - - - _ - --= - �� � - - - " �, - - - - - i _ APPROX. LOCATION OF DETENTION POND ^ c _ � 4 - _ ____ --__ _ _ _ DRAINAGE PLAN AREA OF POND = TBD WQCV = 0.48 AC-FT MODIFIED FAA STORAGE VOLUME = 2.97 AC-FT + z RIGDE/ MV FAR _� W �'� , SHEET: Q _ � o POND 216 k - Know what's below. W D - 2 Call before you dig.