Loading...
HomeMy WebLinkAboutADVANTAGE (RENTAL) CENTER - PDP/FDP - 36-97 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTOffsite flows from the east portion of the properties to the north will not be allowed to enter the new detention pond. These flows will pass by the east side of the pond on the east 10 feet of the site. A shallow swale will be provided along the east 10 feet of the site to carry these offsite flows. Mite flows from the west portion ofthe properties to the north will be carried by the east gutter of the Service Road. This is what has happened historically, and the development of the Advantage Rental site will not cause a change. Flows from the Service Road will not enter the site, and the only flows which enter the Service Road from the site will be from the street sidewalk and from a few feet of landscaping east of the sidewalk. The remainder of the site will drain to the detention pond. In the future, when the lots to the south are developed, this turn around detention may be enlarged to provide more detention for the development on the lots to r the south. Albrecht Homes occupies the lots directly north of the proposed Advantage Rental site. The Albrecht site does not have onsite detention, and there is a paved driveway all along the south side of the Albrecht site. This driveway drains southerly onto the Advantage Rental site, so a curb is proposed all along the south side of the driveway. This curb will intercept the runoff and direct it west to the Service Road or east to the drain swale which will carry the offsite flows to the south. A pipe is proposed along the north side of the building to pick up downspout flows and carry them to the east and then south into the detention pond. Calculation sheets are included in this report which calculate the historic and developed site runoff the offsite flows, the required and provided detention, roof runof, pipe sizing and swale flows. EROSION CONTROL The site is located in a moderate to high rainfall erodibility zone and in a moderate wind erodibility zone. A silt fence will be place along the south side of the site before beginning any excavation. After the site grading is completed and the detention pond and outlet pipe are installed, a sediment trap will be placed over the pond outlet. The site is narrow in the direction of the prevailing wind, so the new building foundation and the structure on the lot to the north will provide adequate wind erosion control barriers. z DRAINAGE AND EROSION CONTROL REPORT ADVANTAGE RENTAL CENTER EXISTING SITE INFORMATION The Advantage Rental site at 4848 South College Avenue is a part of Lots 7, 8, 9 and 10 of the Replat of a Part of Fairway Estates. The site is 250 feet deep west to east and 92 feet wide north to south. The site is vacant ground with a good cover of pasture grass. The lots to the north of the site are all developed, and there are about 200 feet of undeveloped lots to the south between the site and the existing State Farm Insurance Agency site. There are 7 developed parcels to the north between the site and Pahner Drive. Six of these parcels were developed in the County before annexation and no storm water detention was provided so all runoff from these six parcels is to the south along the east side (rear) of the lots or along the west side (Service Road on the front) of the lots. The seventh parcel is the Jensen Homes parcel, -which is the second parcel north of the site, and which has on site detention. A copy of an aerial photo topography showing these properties is included in this report. Also shown on the photo copy is the basin line dividing the flow to the east and the flow to the west. Calculations of these flow quantities are included in the report. The historic runoff from the site is to the southeast. The site runoff combines with the offsite runoff from the north and travels southerly to the State Farm site. The State Farm site was developed several years ago with on site detention and with a swale across its east side which runs from north to south and which carries offske flows to Fairway Lane. There is a small open irrigation lateral ditch located just east of the site. This ditch, which runs from north to south, carries about 3 c.fs. We do not intend to interfere with this ditch or to allow any runoff from the site into the ditch. PROPOSED SITE DEVELOPMENT The Advantage Rental site will be developed with a building and associated paved drive and parking. The south half of the driveway and a portion of the fire truck turn around will be on the property to the south. A separate document easement for utilities, drainage facilities and access will be provided for the offsite construction. Also, since the site is a part of an existing plat, and no new plat is proposed at this time, a separate document easement will be provided for the onsite utilities, drainage facilities and access. Storm water detention will be provided for the difference between the 2-year historic release and the 100-year developed volume. The detention pond will be located on the easterly part of the paved drive and parking, including the fire truck turn around. The turn around will be constructed as a bowl with the low spot in the center. A shallow area inlet will be constructed at the low spot in the center and an outlet pipe will be extended southeast beyond the edge ofthe turn around. The outlet pipe will have a restriction plate over its inlet to control the release rate. The outlet pipe will drain into a swale which directs the flow south to the State Farm site. I 751 TE, Table of Contents 1 Vicinity Map 2-3 Text of report 4 Map of Offsite Basins 6 FTistoric Site Drainage 7-8 Offshe Flows 9 Detention Volume Required 10 Volume of Proposed Detention Pond 11 Detention Pond Outlet and Restricted Opening 12 Roof Runoff From North 1/z of Building 13 Kutter's Pipe Flow Chart 14 - 16 Erosion Control Calculations 17 Erosion Control Collateral Pocket' Grading and Drainage Plan TEWART SSOCIATE S 8� S Consulting Engineers and Surveyors December 15, 1997 Mr. Basil Hamdan Storm Water Utility City of Fort Collins P.O. Box 580 Fort Collins, CO 80522 Dear Basil, Mr. Ronald Rockvam, the owner, and the W. I Frick Design Group have asked our firm to provide storm drainage plans and reports for the proposed commercial site at 4848 South College Avenue. This site is on part of Lots 7, 8, 9 and 10 of the Replat of a Part of Fairway Estates, and is located in the Northwest '/o of Section 1, Township 6 North, Range 69 West, of the Sixth P.M., City of Fort Collins, County of Larimer, State of Colorado. The site is located on the east side of South College Avenue about'/4 mile south of Harmony Road, and is located in the Fossil Creek Basin. We plan to provide detention in an onsite easement,, and also in an easement on the adjacent property to the south. Release will be through a separate document easement across the lots to the south to the existing drainage swale and easement across the State Farm site. The State Farm site is located about 200 feet to the south. Offsite flows from the north will be allowed to pass by on the easterly ten feet of the site just as they have done historically. Offsite flows from the north along the existing Service Road on the west side of the site will remain on the Service Road. No offsite flows from the Service Road will enter the site. Also no flows from the site will drain to the Service Road. ` The report and the drainage plans for the site are prepared in compliance with the City of Fort Collins Criteria. Sincerely, Phillip I. 'Robinson, P.E. & L.S. rrc 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 STORM DRAINAGE AND EROSION CONTROL REPORT FOR ADVANTAGE RENTAL CENTER AT 4848 SOUTH COLLEGE AVENUE IN THE FOSSIL CREEK BASIN PREPARED FOR RONALD ROCKVAM DECEMBER 16,1997 PREPARED BY STEWART & ASSOCIATES, INC. 103 SOUTH MELDRUM STREET FORT COLLINS, COLORADO 80521 970/482-9331