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HomeMy WebLinkAboutGARTH COMMERCIAL PLAZA - PDP - 20-02B - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT14 II I I I I I J� I \ J i winter Cl. 1 Dr. 3 UU ut; ' ua J a ' 1 t�L t I �TSlllf Cl. red Ct 4 ¢ v S _t 119 V/C/N/ T Y MAP SCALE -/"=/cool 1. A I o'S / TE ' January 23, 2003 STEWART$,LSSOCIATES Consulting Engineers and Surveyors Mr. Basil Hamdan Stormwater Utilities City of Fort Collins P.O. Box 580 Fort Collins, CO 80522-0580 Dear Basil, The owner George Holter is now proposing to build Phase II of Lots 1 through 4, Garth Commercial Plaza. The original storm drainage design and report are dated October 14, 1996 and approved by you dated December 6, 1996. That report and plans are included herein. Phase I of this project has been constructed and "AS-BUILTS" submitted to your office in 1997. Phase II's new building, parking lot and driveway layout are very similar to the original layout. Both access drives, one on the North side next to the existing hotel and the one on the South side next to the existing commercial building were constructed with previous phases. This new plan will not change the approved flow directions or the subbasin areas as shown on the original report. Subbasins 5, 6 and Offsite 1 are the original design basins for Phase II. We have recalculated these basins to use the City's new Intensity data. This changed the required detention volume of both Ponds 5 and 6. Additional storm drain pipe and area inlets were added to obtain the increased volume required. Both ponds 5 and 6 will have a 100-year depth of 1.2 feet. Both depths are lower than the original design, which were granted a variance by you. We are again requesting a variance from the City's maximum depth of 12 inches. We are also requesting a variance from the City's extended detention requirement. This site does not have any place or area for that requirement. This is an infill project that was previously approved as layout. An additional pipe and area inlet will be installed to the property to the South at the owner's request. A LTD sewer model was run to show all new pipes and inlets. Erosion control will be to install silt fences along Mason Street, and on both the North and South sides along the existing driveways. Straw bale dikes will be installed around all four area inlets until paving. The foundation will be installed prior to overlot grading for erosion control. The City's required escrow for erosion control is $3750.00. If you have any questions or need any more information regarding the Phase II project please let me know. ' Sincerely, t Franklin DljlK*, P.E. & FDB/meh 9T " INFER bA James H. Stewart and Associates, Inc. GARn,C.,WPIMb���103 S. Meldrum Street • P.O. Box 429 • Ft. Collins, CO 80522 970/482-9331 • Fax 970/482-9382 ADDENDUM TO THE FINAL DRAINAGE AND EROSION CONTROL REPORT FOR LOTS 1 THROUGH 4, GARTH COMMERCIAL PLAZA LOCATED IN THE McCLELLANDS MAIL CREEK DRAINAGE BASIN PREPARED FOR GEORGE HOLTER JANUARY 20, 2003 PREPARED BY STEWART & ASSOCIATES, INC. 103 SOUTH MELDRUM STREET PO BOX 429 FORT COLLINS, CO 80522 OARTH Cmmnsid Plm adddm.pLcbc