Loading...
HomeMy WebLinkAboutSHADELAND TOWNHOMES - PDP - 17-98 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTVICINI l MAP SCALE: 1 "= 1000' r drain. The grading of the site matches the existing grading at the boundary line on the East, West and South sides of the site. There will not be a need for off -site grading easements. EROSION CONTROL: The site is in the moderate rainfall and wind zones. The foundations for the 5-plex and for the garage will be poured as soon as the excavation is completed. The existing driveway gravel base will not be disturbed. Gravel base will be placed between the two foundations as a staging area. A silt fence will be placed along the East property line. The effectiveness of the erosion control is 74.2% which is greater than the required 72.3%. The runoff calculations, the detention pond calculations and the erosion control calculations are enclosed as a part of this report. The grading and drainage plan is also enclosed. This drainage report and the design of the drainage system were made in substantial compliance with the City of Fort Collins Storm Drainage Design Criteria and Construction Standards. If you have any questions during your review of this report, please call. Sincerely, Richard A. Rutherford,'P.E. & L.S. S * 5028 meh STEWART&ASSOCIATES Consulting Engineers and Surveyors March 3, 1998 Mr. Basil Hamdan Storm Water Utility City of Fort Collins P.O. Box 580 Fort Collins, CO 80522 Dear Basil, The following is the final drainage report for 521 East Prospect Road. The site contains 0.442 acres and is in the Spring Creek Major Drainage Basin. The site is described as Lot 2, Holsinger First Subdivision. The site is "I" shaped with the leg being the access from Prospect Road. The site is bounded by single family detached houses on all sides. The site slopes from Southwest to Northeast at an approximate slope of 0.4%. The site is zoned L.M.N. The Fort Collins Housing Authority is proposing to construct five, two-story townhomes and a five bay garage on Lot 2. We have designed an on -site storm water detention pond in the parking area to detain the difference between the two year historic runoff and the 100 year developed runoff The required volume of detention is 3,066 cubic feet. The two year historic runoff rate is 0.16 c.f.s. and the 100 year developed runoff rate is 2.77 c.f.s. The runoff coefficient increases from a historic "C" of 0.25 to a developed "C" of 0.70. The detention pond, as designed will have a volume of 3,686 cubic feet. It is proposed to discharge the storm water from the detention pond in a proposed 12 inch diameter P. V.C. pipe that will discharge into an existing storm drain in Prospect Road. The storm water runoff will then flow Easterly in the existing storm drain to Stover Street and then South to Spring Creek in an existing storm drain. The runoff from the South 1/2 of Prospect Road and the North 25 feet of the driveway flows Easterly in the South gutter of Prospect Road to an existing catch basin at the comer of Prospect Road and Smith Place. The catch basin discharges into the Prospect Road storm drain. There are two offsite sub -basins that drain through this site. Off -site basin "A" is the small lot on the West side of the driveway which will flow through the proposed detention pond. Off -site basin `S" is the rear yards and the rear half of the houses on the South side of the site. Sub -basin `S" sheet flows onto the site and flows through the detention pond to the Prospect Road storm 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 r r 0 FINAL DRAINAGE REPORT FOR 521 EAST PROSPECT ROAD SPRING CREEK DRAINAGE BASIN PREPARED FOR FORT COLLINS HOUSING AUTHORITY MARCH 311998 PREPARED BY STEWART & ASSOCIATES, INC. 103 SOUTH MELDRUM STREET FORT COLLINS, COLORADO 80521 970/482-9331 0 r