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HomeMy WebLinkAboutSite Certifications - 10/06/19971619 a- ES ORMWATER August 27, 1997 ,H RECEIVED WESTEC #95437 Basil Hamdan SEP U 8 1997 City of Fort Collins Stormwater Utility ©be �✓ 235 Mathews n� _s/ Q�C jZBtN Fort Collins, CO 80522%� RE: George T. Sanders Co. P.U.D. - Drainage Certification Response to Comments Dear Mr. Hamdan: In response to your comments dated July 8, 1997 the following items have been addressed to ensure approval of the as -built plans. Comment 1. A complete copy of the survey spot elevations has been provided. These elevations correspond to the points identified on the Grading and Drainage Plan submitted previously. Comment 2. The size of the detention pond outlet pipe was verified and is identified on a copy of the Utility Plan provided. Comment 3. The Utility Plan details indicate the measured elevation of area inlets and storm drains discharging to the detention pond. Invert elevations at the north and south dock drains and grate elevations on the inlet boxes are provided as well as the pipe diameters and inlet box dimensions. Comment 4. & Comment 5. The location and size of 6"x 6" timbers placed in the parking area are shown on the Utility Plan. Runoff from the parking lot was washing out landscape bark and causing erosion in the detention pond. The timbers were placed along the edge of the asphalt to prevent high velocity sheet flows from eroding the landscaped area between the parking lot and the detention pond. The onsite manager stated that the runoff passes through and should prevent further erosion. Since there is not a tight seal between the bottom surface of the timbers and the pavement surface, low flows will pass under and between the timbers, higher flows are slowed down before leaving the asphalt surface. Sod grass growth is spreading into the eroded areas and getting re-established. Comment 6. Invert elevations of the storm drain pipes beneath the two dock drains, at the outlet to the detention pond and at the pond outlet structure are provided. Certification of the invert elevations for each inlet addressed in Comment 3, are provided by documentation of measurements made August 8, 1997 and identified on a copy of the Utility Plan. Enclosed is a copy of the survey information, the Utility Plan details showing profiles of the storm drain and detention pond outlet and the location of timbers at the south end of the parking lot for the referenced project. If you have further questions or require additional information please call. Sincerely, Water, Watte,,> RAVEHlYAw., dba WESTEC Richard L¢mann, I Project M� Civil Engine}`��i�