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Home My WebLink AboutCENTERPOINT PLAZA - PDP - 35-01 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTAugust 29, 2001 Stormwater Utility City of Fort Collins P.O. Box 580 Fort Collins, CO 80522-0580 Gentlemen, The following is the cost estimate for the erosion control measures for Centerpoint Plaza. 1. CONSTRUCTION COSTS: 550 LF Silt Fence @ 3/ft Straw Bale Dike Total Construction Cost Estimate 2. RESEEDING COSTS: Reseeding -- 7ac -2.5 Existing Lot -0.3 Road Row 4.2ac @ $655/ac 3. ESCROW REQUIRED FOR SITE: 1.5 X $2,751 $ 1,650.00 $ 100.00 $ 1,750.00 $ 27751.00 $ 4,126.50 If you have any questions or need more information regarding this estimate please let me know. Sincerely, 1 C Franklin D. Blake, FDB/meh 1 1 1 Runoff from this site will be directed to the Southeast corner of the site and then released into the existing drainage ditch that flow East to the Poudre River. The ditch has the capacity to handle the Historic two-year flow rate. Runoff will be directed from the Northwest comer of this site East to the center access road; then South to the end of the parking area in the gutter; then'East in a 3 foot pan to the detention pond. Runoff from Lot 2 will be directed South to a concrete pan constructed between the existing loading dock and railroad spur to the detention pond. The runoff on that portion of Midpoint Drive lying West of the middle North -South access road will be directed through our site. The rest of Midpoint Drive will flow East as it now exists. This project will put in escrow monies for the development of Timberline Road. This project is dedicating an additional 40.5 feet of right-of-way. At present runoff from Timberline Road is North to an existing culvert at Midpoint Drive; then North in a borrow ditch to Spring Creek. Until Timberline Road is designed we are leaving this area as it now exists. Timberline Road is proposed to be designed from Prospect Street to Drake Road as one project. The City of Fort Collins is the Project Developer. The detention pond is designed to store the 100-year runoff plus the 40 hour extended detention. The bottom of the pond is at elevation 4906.93 feet. The grass spillway elevation is at 4909.35 feet. Runoff over the spillway will be East along the South property line. The top of the pond will be at elevation 4910.00 feet. A variance is requested from the City of Fort Collins requirement of one foot of free board. For the extended detention the top of the area inlet will be one foot above the bottom of the pond. 1 EROSION CONTROL: The site is in the high rainfall erodibility zone and in the moderate wind erodibility zone. The site will be developed in two phases. Lot 1 is Phase I along with the access road which is in lot 2 and also the detention pond. The extended detention will also be constructed with the pond. A straw bale dike will be constructed around the area inlet. Also a silt fence will be constructed along the East property line and remain in place until all construction is completed. The historic and developed calculations are included herein. The report and design of the drainage system are in compliance with the city of Fort Collins Storm Drainage Design and Criteria. The erosion control required escrow amount is $4,126.50. If you have any questions or need any more information regarding this project or report please 1 let me know. ' Sin rely, J0 ranklin D. Blaltie E. 1 1�pt.L : _ "*isles at00 ' STEWART$ASSOCIATES August 27, 2001 Consulting Engineers and Surveyors Mr. Basil Hamdan Stormwater Utilities City of Fort Collins P.O. Box 580 Fort Collins, CO 80522-0580 Dear Basil, EXISTING SITE: The following is a Preliminary Drainage, Erosion Control, and Extended Detention Report for Centerpoint Plaza which is a Replat of Lot 1, Nor -Colo Subdivision and a Tract of Land situate in the Northwest 1/4 of Section 20, Township 7 North, Range 68 West of the Sixth P:M., Fort Collins, Larimer County, Colorado. The area is 7.0 acres net. This area does include 40.5 feet of Timberline Road and 3.0 feet of Midpoint Drive. This project is located in the City of Fort Collins Spring Creek Drainage Basin. This project is bounded on the West by Timberline Road; on the North by Midpoint Drive; on the East by Lot 2, Nor -Colo Subdivision, which is undeveloped; and on the South by the IBurlington Northern Railroad. There are no offsite flows onto this site On Lot 1 there is an existing one story warehouse building with an asphalt parking area and asphalt driveway from Midpoint Drive. There is also an existing railroad spur on the East side of the _. existing building. The site West of this existing building is grass, bare ground, and weeds. The historic slope of this site is West to East with a small portion flowing to Midpoint Drive to the existing culvert; then North is a borrow ditch along Timberline Road to Spring Creek. The average slope of this site is 1.25%. DRAINAGE CRITERIA: Due to the small size of this site, the Rational Method has been utilized to determine peak runoff rates and required detention pond volumes. The release rate is the two-year Historic rate. Design factors used are in accordance with the recommendations of the City of Fort Collins Storm Drainage Criteria and Construction Standards Manual. DEVELOPED SITE: This project is proposing to develop 3 officelstorage buildings with parking, landscaping. The existing warehouse is to remain. Access is to Midpoint Drive. At present the project will be developed in two phases; Lot 1 being Phase I and Lot 2 being Phase H. 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 I I I I I 1 1 1 1 1 1 1 1 1 k� 'PRELIMINARY DRAINAGE, EROSION CONTROL & EXTENDED DETENTION REPORT FOR CENTERPOINT PLAZA SITUATE IN THE SPRING CREEK DRAINAGE BASIN PREPARED FOR COBALT DESIGN BUILD AUGUST 27, 2001 PREPARED BY STEWART & ASSOCIATES 103 SOUTH MELDRUM STREET P.O. BOX 429 FORT COLLINS, CO 80522 TEL. 970-482-9331 FAX. 970-482-9382