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Home My WebLink AboutNORTHERN COLORADO FEEDERS SUPPLY - PDP - PDP140010 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTBOULDER I FORT COLLINS I WINTER PARK JVA, Incorporated 25 Old Town Square Suite 200 Fort Collins, CO 80524 Ph: 970.225.9099 Fax: 970.225.6923 Toll Free: 877.444.1951 Web site: www.jvajva.com E-mail: info@jvajva.com July 23, 2014 Mr. Glen Schlueter City of Fort Collins Utilities – Stormwater Engineering 700 Wood Street Fort Collins, CO 80521 RE: Northern Colorado Feeders Supply, 300 Hickory Street - Drainage Letter JVA Job No. 2259c Dear Mr. Schlueter: This letter has been prepared to summarize the drainage concept, solutions and changes in impervious area associated with the site improvements for the Northern Colorado Feeders Supply project located at 300 Hickory Street in the City of Fort Collins. Existing Drainage Patterns The existing site is predominantly paved asphalt and consists of two large storage buildings and an office utilized by the previous owner, Barton Supply. The existing ground surface is relatively flat, generally sloping either north or south at grades ranging from 0.5% to 2.0%. The majority of stormwater runoff is conveyed via surface flow either to the north into an existing grass-lined swale running adjacent to the railroad tracks along the north boundary of the property, or to the south and then east into the surface drainage system on Hickory Street. The site has been divided into four hydrologic basins for analysis. Basins A and B represent drainage that sheet flows south across the site and temporarily ponds in the existing depressed paved areas located along the front of the property. Collected stormwater then drains out of these areas by running over and down the two existing driveway approaches to the street gutter, where it is discharged into the storm drain system at an existing curb inlet to the east. Basin C represents the runoff from the remainder of the developed site, draining out to the north. This runoff joins the flows from Basin D and is channelized in an existing west-to-east-draining grass-lined swale paralleling the railroad tracks. This swale continues behind the two eastern neighboring properties on Hickory and ultimately spills out into the gutter on College Avenue. From there, runoff flows south on College for half a block before it is collected at an existing curb inlet at the intersection of College and Hickory. All four basins eventually convey stormwater to the Poudre River to the south and east of the site. See Figure 1: Drainage Exhibit for the drainage basin boundaries and runoff calculations. The site is located outside FEMA and City of Fort Collins mapped 100-year and 500-year floodplains, per FEMA Flood Risk Map Panel number 08069C0977G, effective date 06/17/2008. Proposed Drainage Patterns Proposed drainage patterns are to remain the same as the current. The existing use of the site – light industrial and retail - is also to remain the same. In general, as part of this project, Northern Colorado Feeder Supply proposes to retain the existing storage buildings with minor structural modifications, tear down the existing office space and foundation, and construct a new office/retail Northern Colorado Feeders Supply July 23, 2014 2 of 2 BOULDER I FORT COLLINS I WINTER PARK building over the existing office footprint with a new ADA compliant pedestrian sidewalk access from Hickory Street. Additionally, approximately 1,390 square feet of landscaped/grass area will be provided in front of the new office and adjacent to the existing landscape areas along the front of the property. It follows that the proposed improvements will slightly decrease the total impervious area on the site, from 70.84% to 69.27%. See Figure 1: Drainage Exhibit for a summary of the existing and proposed impervious areas. Chapter 2 of the Urban Drainage and Flood Control District’s Urban Storm Drainage Criteria Manual Volume 3 (USDCM) provides guidelines for the selection of appropriate structural BMPs for a site that is to be developed or redeveloped. 300 Hickory is best characterized as a “conventional redevelopment” with just over 1 acre of impervious area on the project site. The BMP decision tree for such sites is provided in Figure 2-2 of the USDCM. The site and surrounding vicinity is comprised of hydrologic soil group Type C soils, per the NRCS soil survey, with a depth to bedrock of greater than 5 feet. Permeable pavement (with partial or no infiltration) and/or the use of a “green roof” or grass swale/buffer are the recommended runoff reduction practices for this scenario. The existing grass swale at the rear of the property currently performs this function for the majority of the runoff generated on the site. Treatment and slowed release of the water quality capture volume occurs at the southeast and southwest corners of the property in the existing paved detention areas as well as by the existing grass swale at the rear. Since these existing features facilitate sedimentation and filtering while limiting erosion, and since the existing unchanged use and limited redevelopment of the site will not subject natural drainageways to increased frequency, rate, duration, or volume of runoff, the existing measures to reduce water quality and quantity impacts are sufficient for this site and no additional structural BMPs are proposed. Erosion and Sediment Control During construction, temporary erosion and sediment control practices will be used to limit soil erosion and sediment discharge off the site. These temporary erosion control devices include curb rock socks, inlet protection, sediment logs, and silt fencing. Please feel free to contact myself or Karen Brigman to discuss any questions you may have. Sincerely, JVA, INCORPORATED By: ________________________________ By: ________________________________ Brian Campbell, P.E. Karen Brigman Project Manager Design Engineer CC: Architecture Plus By: ________________________________ By: ________________________________ Brian Campbell, P.E. Karen Brigman Project Manager Design Engineer 3" water vent 4" water vent "fort collins water" "fort collins water" "gas riser" "RR x-ing" "RR x-ing" open air structure on 4' stem wall wood frame building on concrete concrete canopy over concrete canopy over asphalt center line union pacific railroad 4978 4976 4977 4978 4979 4979 4978 4978 53.51' Utility easement per Exception Item No. 11 50.0' Waterline Easement per Exception No. 20 20.0' Waterline Easement per Exception No. 17 30.0' Approx.Track Easement per Exception No. 14 concrete asphalt asphalt asphalt asphalt asphalt edge of asphalt edge of gravel edge of asphalt 25' dedicated UPRR ROW from centerline track found 3/8" iron rod found rod with orange cap illegible POINT OF BEGINNING 4978 4978 35' dedicated ROW per Schedule A Exception and Exception Item No. 19 from section line REVISIONS SHEET CONTENTS DRAWN CHECKED DATE SHEET NO. REUSE OF DOCUMENTS: THE IDEAS AND DESIGN INCORPORATED HEREON, AS AN INSTRUMENT OF PROFESSIONAL SERVICE, IS THE PROPERTY OF ARCHITECTURE PLUS AND IS NOT TO BE USED FOR ANY OTHER PROJECT WITHOUT PRIOR WRITTEN AUTHORIZATION OF ARCHITECTURE PLUS 318 East Oak Street + Fort Collins 80524 1531 West 29th Street + Loveland 80538 970.493.1220 + 888.698.7897 + www.aplusarch.com NORTHERN COLORADO FEEDERS SUPPLY JULY.2014 KRB BJC ISSUE FOR PERMIT 300 HICKORY STREET FORT COLLINS, COLORADO 80524 NO. BY DESCRIPTION DATE FIG.1 FIGURE 1: DRAINAGE EXHIBIT