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Home My WebLink AboutCHOICE CENTER MIXED-USE REDEVELOPMENT - PDP - PDP110006 (15-08) - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTDEVELOPMENT PROPOSAL The Choice Center Mixed -Use Redevelopment (CC) project encompasses 10.49 acres and will be a mixed -use development. When completely constructed, CC will contain 283 units of student housing and 46,000 square feet of retail space. The CC anticipates constructing the new residential buildings, retail buildings, and rehabbing the existing retail buildings in two phases of construction. When complete, the development anticipates a total of 262,700 square feet of residential space and 46,000 square feet of retail space. The proposed residential space targets undergraduate and graduate Colorado State University (CSU) students. Concurrent with the city approval process for this project, the developer is seeking CLOMR approval from FEMA to! mitigate the current FEMA Floodplain issues affecting the property (See sheet 6 of 14 for the current FEMA Floodway/Floodplain boundaries). The developer and its consultant, Nolte Associates, are working closely with city staff to allow for the mitigation construction to occur prior to the site work associated with the development. The aforementioned improvements will be constructed in two phases. _ Phase l: This project's first phase will include construction of the four story student housing (i.e., Building 1), the south parking lot, and the north parking lot. Additionally, the existing retail located adjacent to the north of Stuart Street will be razed and replaced with student housing and retail space (i.e., Building 2). Phase ll: The existing retail buildings that are located north of the existing Tire Center will be rehabbed. Each building currently has a 60 foot depth. The developer plans to increase the depth to 90 feet by adding 30 feet to the east side of each building. .A The existing local developed runoff from Building 4 (See sheet 6 of 14), which is the northernmost retail building (1635 to 1681 South College Avenue), drains both east and west. The roof drains along the rear of the building (i.e., west side) discharge onto the existing asphalt (to remain) and then into three area inlets (to remain) behind the building. The roof drains along the front of the building discharge onto the existing asphalt parking lot and combine with the runoff from the parking area. These flows then drain north and into the Chuck',E. Cheese parking lot along grades averaging 0.60%. The developed runoff from Building 3, which is the retail building south of Building 4 (1701 to 1739 South College Avenue), drains to the east and west. The roof drains along the rear of the building (i.e., west side) discharge onto the existing asphalt and then into three area inlets behind the building (i.e., one at each rear corner and a third behind the building). Some of the runoff that drains to the rear of the building appears to sheet flow across the asphalt and flow to the southwest where it combines with the runoff from the now vacant Johnson Center Mobile Home Park site. The roof drains along the front of the building discharge onto the existing asphalt parking lot and combine with the runoff from the parking area. These flows then drain south and out into College Avenue along grades averaging 0.80%. The on -site soils consist of Altvan-Santana loams, 0 to 3 percent slopes; Altvan-Santana loams, 3 to 9 percent slopes; Fort Collins Loam, 1 to 3 percent slopes; and Nunn loam, wet, 1 to 3 percent slopes (Refer to Appendix C for a copy of the NRCS soils map). All but the Nunn clay loam, which is a NRCS Hydrologic Soil Group (HSG) `C' soil, are a part of NRCS HSG `B'. Descriptions of each soil type follow: 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 course texture. These soils have a moderate rate of water transmission. Group C: These soils have a slow 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 deeply course texture. These soils have a slow rate of water transmission. At this time, we do not have a soils report; therefore, we cannot comment on the local groundwater conditions or specific characteristics of the existing soils. Spring Creek is the proximate major drainage way to the project site. It is located directly south of the project site in Creekside Park. BACKGROUND SITE LOCATION The Choice Center Mixed -Use Redevelopment (CC) is located at 1609, 1635, 1653, 1669, 1681, 1705, 1729, 1733, 1739, 1797 South College Avenue, Fort Collins, Colorado 80525 and comprised of the following three parcels: Lot 1B, replat of a portion of Lot 1 of the Spring Court Subdivision; a portion of Lot 2, Spring Court Subdivision; and a portion of Lot 3, Fox Shopping Center Subdivision The subject site is located in the Northeast Quarter of Section 23, Township 7 North, Range 69 West of the 6"' P.M., City of Fort Collins, County of Larimer, State of Colorado. CC is bordered to the north by existing development (i.e., A portion of Lot 3, Fox Center Shopping Center Subdivision and Lot 2, Fox Shopping Center Subdivision); to the south by Creekside Park; to the east by College Avenue (U.S. Highway 287); and to the west by the Colorado and Southern railroad tracks. EXISTING SITE DESCRIPTION The subject property is comprised of f 10.49 acres. (Excel sheet shows 10.40 acres) The subject property, which is currently divided into three parcels, is a mix of existing retail, a storage facility and car wash, the former Johnson Center Mobile Home Park site (now vacant), and a vacant lot north of Creekside Park. Parcel 1 is currently developed with an existing carwash and storage facility. Both will be razed. The existing grade varies between 2.00% and 7.00%. The existing local developed runoff drains into several existing area inlets. This storm infrastructure will be abandoned with the proposed redevelopment. Parcel 2 is currently vacant except for a small asphalt area along the west property line. The existing runoff generally sheet flows to the east along grades of less than 1.00%. Parcel 3: is comprised of several developed and undeveloped areas. The vacant portion of Parcel 3 was the Johnson Center Mobile Home Park. It was destroyed on the night of July 28ffi, 1997 during a storm event that dropped approximately 14.5 inches of rain over thirty-one hours in parts of Fort Collins. The resulting flooding conditions caused over 200 million dollars in damage across the city. The vacant area is comprised of existing mature trees, native grasses, weeds, and several un- vegetated areas. The northernmost region of this area is paved where it connects to the neighboring property. The existing local developed runoff generally flows to the south-southeast along grades varying between 0.50% and 5.00%. An isolated low point prevents some surface runoff from reaching the existing inlet that drains directly into the existing 48" RCP on the north side of Stuart Street. PE CERTIFICATION AND SEAL This report for the preliminary design of the Choice Center Mixed -Use Redevelopment was prepared by me or under my direct supervision in accordance with the provisions of the City of Fort Collins Storm Drainage Design Criteria and Construction Standards. I understand that the City of Fort Collins and its designated city authority do not and will not assume liability for drainage facilities designed by others. Stamp and Signature at Final Registered Professional Engineer State of Colorado M TABLE OF CONTENTS Tableof Contents............................................................................................................................. i PECertification and Seal................................................................................................................ ii Background..................................................................................................................................... 1 SiteLocation................................................................................................................................ 1 ExistingSite Description:............................................................................................................ 1 DevelopmentProposal.................................................................................................................... 3 Storm Water Basins and Drainage Patterns.................................................................................... 4 StormWater Quality....................................................................................................................... 6 r General.........................................................................................................................................6 _ Temporary Structural and Non -Structural Practices.................................................................... 6 Structural Practices................................................................................................................... 6 Non -Structural Practices........................................................................................................... 7 OtherControls.......................................................................................................................... 7 FinalStabilization........................................................................................................................ 8 PermanentStormwater Quality.................................................................................................... 8 WetlandsImpacts............................................................................................................................ 9 Hydrology and Hydraulic Criteria................................................................................................ 10 - Development Criteria Reference and Constraints..................................................................... 10 _ Hydrology Criteria..................................................................................................................... 10 Hydraulic Criteria and Calculations.......................................................................................... 10 - Storm Water Detention................................................................................................................. 11 _ Developed Storm Water Conditions............................................................................................. 12 Overview....................................................................................................................................12 - _ Integration with SWMM and CLOMR.................................................................................. 12 Sub -basin Descriptions.............................................................................................................. 12 StormDrain System Design...................................................................................................... 15 Conclusions...................................................................................................................................16 Compliancewith Standards....................................................................................................... 16 Requestfor Variance(s)............................................................................................................. 16 References..................................................................................................................................... 17 APPENDIX A DEVELOPED CONDITION APPENDIX B PRELIMINARY STORM DRAIN SYSTEM DESIGN APPENDIX C NRCS SOILS MAPPING RATIONAL METHOD SWMM INFORMATION FEMA MAPPING INFORMATION Back Pocket: Preliminary Drainage and Erosion Control Plan, Sheet 6 of 15 `'A PRELIMINARY DRAINAGE AND EROSION CONTROL REPORT CHOICE CENTER FORT COLLINS, COLORADO i r Prepared for: CAPSTONE DEVELOPMENT CORPORATION 10 431 OFFICE PARK DRIvE BnmiNGHAM, ALABANiA 35223 10 10 10 Submitted on: " July 1, 2008 10 Prepared by: 10 Jim Sell Desigd, Inc. 153 Nest Mountain Avenue Fort Collins, Colorado 80524 Phone 970.484.1921 FAX 910.484.2443