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HomeMy WebLinkAboutGRANT STREET CORNERS - PDP - 20-08 - REPORTS - DRAINAGE RELATED DOCUMENTGrant Street Corners PDP Page 2 No adverse affects to surrounding properties are anticipated from the proposed development of this Site. Erosion control measures should be utilized to mitigate erosion and control sediment during construction. Standard Best Management Practices should include, but are not limited to, perimeter silt fencing, vehicle tracking control, and inlet protection. Thank you for your time and consideration. If you have any questions or concerns, please don't hesitate to contact me. Respectfully, Stewart & Associates Consulting Engineers & Land Surveyors 094..E Kevin Forbes Registered Professional Engineer State of Colorado No. 35265 MOO .a STEWARTMSSOCIATES Consulting Engineers and Surveyors September 11, 2008 City of Fort Collins Stormwater Department Attention: Glen Schlueter P.O. Box 580 Fort Collins, CO 80522-0580 RE: Stormwater Plan — Grant Street Corners PDP Mr. Schlueter: Grant Street Corners PDP (Site), being a replat of lots 13 through 19, Block 1, Westlawn Addition to Fort Collins, is located in the Northwest Quarter of Section 14, Township 7 North, Range 69 West of the 6th Principal Meridian, City of Fort Collins, County of Larimer, State of Colorado. It is bounded on the east by Grant Street, on the South by West Myrtle Street, and on the west and north by residential properties. The total Site area is approximately 1.35 acres; containing seven existing houses, four garages, one carport, and paved sidewalks and drives/parking areas. This project proposes to replat the seven properties and add four new single-family residences. Three of the garages and the carport will be removed, and asphalt parking areas added at the alley along the west side of the Site. One existing drive and curb cut, as well as portions of existing sidewalk along Grant Street and on Lots 5 and 7 will be removed, and new sidewalk will be constructed along the entire eastern boundary. The Site is zoned NCM — Neighborhood Conservation Medium Density District. Portions of Lots one through four drain southward to Myrtle Street, then east to an existing curb inlet near the intersection with Grant Street. The majority of the Site generally slopes in a southwest -to -northeast direction, draining to Grant Street, then northward. Addition of the four new homes (600 sf each), new sidewalk along Grant Street (1,266 so, and 2,595 sf of asphalt parking along the alley result in a total of 6,261 square feet of new impervious area. The removal of existing sidewalks (726 so, 2,415 sf of existing gravel area on lot seven (50% impervious), concrete driveway (410 so, and the three garages (1,081 so results in a total of 3,425 square feet of additional pervious area. The resulting net increase in impervious area is 2,836 square feet. The Site lies within the Old Town Drainage Basin of the City of Fort Collins. There are no Master Plan Basin Recommended Improvements for the Site. It is not within any floodplain indicated by either the City of Fort Collins or FEMA Flood Insurance Rate Maps. Because the proposed increase in impervious area of the Site is less than 5000 square feet, water quantity detention is not required. Water quality treatment is provided for this Site in the Udall Natural Area's water quality treatment facility. No changes to the existing drainage facilities are necessary, and a Grading Plan is all that is required (See sheet 4 of the Utility Plan set). James H. Stewart and Associates, Inc. 103 S. Meldrum Street • P.O. Box 429 • Ft. Collins, CO 80522 970/482-9331 • Fax 970/482-9382