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HomeMy WebLinkAboutDELLENBACH SUBARU - PDP - 50-98 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT�I Table of Contents 1 Vicinity Map 2 Copy of Foothills Basin Plan 3 & 4 Basin Calculations Pocket Copy of Drainage and Erosion Control Plan 20 feet south of Swallow Road and there are two 30 inch wide combination curb and gutter inlets. The concrete pan across the frontage road will be replaced with a curb and gutter when the frontage road is blocked off The removal of the frontage road will not change the drainage patterns at the College -Swallow intersection and the proposed construction on the Dellenbach Subaru site will have no effect on the existing stormwater flows at the College -Swallow intersection. There are no offshe flows onto the site. The autoparts store located west of the site drains to Swallow Road and the Dellenbach Motors lot to the south of the site drains to the southeast to the frontage road. Erosion control will need to be provided during parts of the construction period. The existing pavement will be removed at the new building site and the foundation will be installed immediately after, so bare soil will not be a problem in his area. The curb returns and cross pan of the frontage road and Swallow will be removed and quickly replaced with curb and gutter. The removal of the pavement along the frontage road will expose bare soil for probably several months before parking lot pavement and new turf is installed, so a sediment trap will need to be provided at the south end of this removal area. A temporary gravel berm can be placed across the lower end of this area just north of the new driveway off of South College Avenue. All of the areas where pavement is removed are small aAd narrow, so additional protection from wind erosion is unnecessary. The erosion control collateral should be the minimum of $1,000 dollars. There are calculations included in this report of the stormwater runoff quantities from this site to Swallow Road and to the south. This report has been prepared in compliance with City of Fort Collins criteria. ISincerely, Phillip I. kobinson, P.E. & L.S. meh TEWART SSOCWE S 8� S Consulting Engineers and Surveyors September 8, 1998 Mr. Basil Hamdan Storm Water Utility City of Fort Collins P.O. Box 580 Fort Collins, CO 80522-0580 Dear Basil, The Dellenbaoh Subaru P.D.P. is located at the Southwest comer of South College Avenue and Swallow Road. The site is the existing Round -The -Corner restaurant and parking lot, and there are modifications proposed to the frontage road and to the west curb along South College Avenue. The net hard surfaced area will be decreased by this proposed development, and no on site detention is planned for the site. The site is located in the Foothills Drainage Basin, and according to the Foothills Basin Master Plan, a portion of the site may be within the 100 year flood plain after basin improvements have been done west of South College Avenue. These improvements, which include installing a 48 inch pipe under the railroad and under the Larimer County Canal No. 2 to carrywater from the west to College Avenue, have not been installed, and therefore, none of the existing site is within a 100 year flood plain. The existing Round -The -Comer building will be maintained and a new building will be constructed adjoining the west side of the existing Round -The -Comer building. The floor of the new building will be placed at the same gr ide as the existing Round -The -Comer building. This new building will replace existing concrete and asphalt surfaces. The existing frontage road along the east side of the site will be vacated and the pavement will be removed. A portion of the pavement will be replaced for the proposed reconfigured parking lot, and a new 4 foot concrete sidewalk will be installed; but approximately 5800 square feet (48 percent) of the existing paved area in the frontage road will be replaced with turf and 2400 square feet (20 percent) will be replaced with grasscrete. Runoff from most of the site drains to the southeast and will drain across the grassed areas. The grassed drainage path will provide a water quality feature for the project. There is a high spot in the existing frontage road which is about 50 feet south of Swallow Road, so stormwater does not go south on the frontage road from Swallow Road. There is an existing pan across the frontage road on the south flow lime of Swallow Road which carries runoff to the catch basins on the west flow line of College Avenue. These catch basins are located about 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 REPORT FOR DELLENBACH SUBARU P.D.P. LOCATED IN THE FOOTMLLS BASIN PREPARED FOR DELLENBACH MOTORS SEPTEMBER 891998 PREPARED BY STEWART & ASSOCIATES, INC. 103 SOUTH MELDRUM ST. P.O. BOX 429 FORT COLLINS, CO 80522 TEL. 970-482-9331 FAX.970-482-9382