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Home My WebLink AboutRAFFERTY'S PUD - FINAL - 17-95A - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTDRAINAGE REPORT RAFFEM Y'S BOARDWALK AVE. FORT COLLINS, CO. Final Drainage and Erosion Control Report Rafferty's P.U.D. Page 2 pond. Overflow will be to the existing drainage channel. Overflow from the existing channel will be to Whalers Way. All developed grass and landscape area will have a minimum of a 2% slope. The parking lot has a minimum of a 1% slope. Runoff from Boardwalk Drive and Whalers Way will remain as existing. Runoff from Harmony Road will be directed in a 15 inch pipe to this site's proposed detention pond. The existing drainage channel will remain in place except where crossing the access drive to Whalers Way. A 30 inch RCP will be installed under this access road. The Northwest area of this proposed site lying North of the access road to Boardwalk Drive and West of the access road to Whalers Way will be left as existing at this time. The existing runoff from this area will flow into the proposed detention pond. Future development will probably happen in this area but at this time, there is no proposed development. When this future site is developed, they will be required to resubmit for approval a new drainage report for this site. Any new design will still require a release rate from this total site of 0.5 cfs per acre. EROSION CONTROL: - This site is in the city's moderate wind erosion area. With the placement of a silt fence that runs North/South through the middle of the construction area, wind erosion will help be controlled. This site is in the city's moderate rainfall erosion area. Erosion will help be controlled by 1) the placement of a gravel filter on the existing 4 foot curb inlet North of Whalers Way on Boardwalk Drive; 2) straw bale dike across the existing drainage channel before the existing 30 inch outlet pipe; 3) placement of a straw bale dike at the headwall of the detention pond and another straw bale dike approximately 200 feet South across the 2 foot concrete pan in the detention pond and 4) by a silt fence along Harmony. Road, along the East property line and along Whalers Way from the East property line to the access road. The City's required escrow amount for this site's erosion control is $3990. Franklin D. Blake, P.E. & L.S. * � v 7 5839 : Secretary/Treasurer FINAL DRAINAGE AND EROSION REPORT OF RAFFERTY'S P.U.D. Due to the small basin size, the Rational Method has been utilized to determine peak runoff rates and required detention pond volumes. Design factors used are in accordance with the recommendations of the City of Fort Collins Storm Drainage Criteria Manual except for the predetermining release rate. In accordance with design criteria, the 100-year runoff from the developed site will be detained in an on -site detention pond. SITE LOCATION: This site is located in the Southeast 1/4 of Section 36, Township 7 North, Range 69 West of the Sixth P.M., Fort Collins, Larimer County, Colorado. The site area is 5.21 acre more or less. This site is an "infill site" with completed development on all sides. On the South side is Harmony Road; on the West side is Boardwalk Drive; on the North side is Whalers Way and on the East is "The Mallards," a single family development. This site is located in the McClellands/Mail Creek Master Plan area. HISTORIC SITE: This site presently covered with nature grasses, weeds and bare soil. The site slopes Northeast at about 1%. There is an existing 24 inch R.C.P. entering the Northwest comer of the site (Boardwalk Drive and Whalers Way). This pipe is an outlet from the Pier Condominiums existing detention pond on the West side of Boardwalk Drive. Runoff from this pipe then crosses the North side of this site in an open channel to an existing 30 inch R.C.P. located at the Northwest comer of this site. Runoff into the pipe flows to the Whalers Cove existing detention pond in a storm sewer system. Harmony Road is developed. Runoff from the North 1/2 of this road is East/Northeast at about 1%. There is an existing small undefined drainage swale on the North side of the asphalt. Boardwalk Drive is developed. Runoff from the East 1/2 of this street is North to an existing 4 foot curb inlet about 50 feet North of Whalers Way. Runoff from this inlet is to the Pier Condominiums existing detention pond. Whalers Way is developed. Runoff from the South 1/2 of this street is East at about 1%. Runoff is to an existing 4 foot curb inlet located at the Southwest comer of Whalers Way and Seaway Circle about 150 feet East of our site. DEVELOPED SITE: The proposed site will be developed with a Raffertys Restaurant, a parking lot with access from Boardwalk Drive and Whalers Way. An 80 foot wide landscape buffer area along Harmony Road is proposed per The Harmony Road Corridor recommendation. All onsite runoff will be directed to a detention pond along the East side of the site. The detention pond will release at the required rate of 0.5 cfs per acre for the 100-year event. Runoff will be into the existing drainage channel along the North side of this site. Runoff as stated before in this channel is to the Whalers Cove existing detention pond. An Emergency Spillway is designed at the North end of the detention STEWART&ASSOCIATES Consulting Engineers and Surveyors June 18, 1995 Mr. Basil Hamdan Stormwater Utility City of Fort Collins P.O. Box 580 Fort Collins, CO 80522-0580 RE: Rafferty's P.U.D. Dear Mr. Hamdan: Enclosed for your approval is the Final Drainage and Erosion Control Report for the proposed Rafferty's P.U.D.. Proposed development for this site is a restaurant and associated utilities, parking area, and drainage facilities. A portion of this site will remain undeveloped at this time. Future development may occur on this area, but there are no plans at this time. This proposed site is in the McClellands/Mail Creek Master Plan developed in 1980 and revised in 1986 by Greenhome and O'Mara, Inc. for the City of Fort Collins. Release rates from this proposed site shall comply with 0.5 cfs per acre for the 100-year event as required and stated in that said report. Due to the small basin size, the Rational Method has been utilized to determine peak runoff rates and required detention pond volumes. Design factors used are in accordance with the recommendations of the City of Fort Collins Storm Drainage Criteria Manual except for the predetermining release rate. In accordance with design criteria the 100-year runoff from the developed site will be detained in an on -site detention pond. Ifyou have any questions or need anymore information regarding this project, please let me know. Yours truly, ran�lni pl'Sl e, P. . Secretary/Treasurer cc: Maxwell Architects James H. Stewart and Associates, Inc. 103 S. Meldrum Street P.O. Box 429 Ft. Collins, CO 80522 303/482-9331 Fax 303/482.9382 FINAL DRAINAGE AND EROSION CONTROL REPORT OF RAFFERTY'S P.U.D. va :l ol J\ all 817 ICIJA MAXWELL ARCHITECTS 631 SECOND AVENUE SOUTH, SUITE 1F NASHVILLE, TENNESSEE, 37210 JUNE 189 1995 BY STEWART & ASSOCIATES, INC. 103 SOUTH MELDRUM STREET FORT COLLINS, COLORADO 80521 970/482-9331 Final Storm.Drainage Report for RAFFERTY'S P.U.D. June 1995 Stewart & Associates Consulting Engineers and Surveyors 103 South Meldrum Street Fort Collins, Colorado 80521 (303) 482-9331