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Nlake WE P12/FP-CS 890106GINN, INC. CONSULTING ENGINEERS January 6, 1989 Taryon Bowman City of Coppell P.O. Box 478 Coppell, TX 75019 Re: Northlake Woodlands East #12 Final Plat and Construction Plans DRC - Engineering Dear Taryon: We have reviewed the above referenced subject and offer the following comments. Applicant needs to add all applicable notes to the final plat as per the City's Comprehensive Floodplain Management Ordinance (CFMO). Reference items on pages 33-35 of the CFMO. Applicant must include construction plan set. a lot grading plan in the Applicant must include any applicable City of Coppell Standard Construction Detail sheets in the construction plan set. Minimum 425' centerline radius is required per the Sub- Division Ordinance. Crestview Court currently shows curve #2 to have a 75' radius, therefore, either a revision to the curve layout or a variance request would be required. Due to the street being a cul-de-sac and the curve being located at the end of the street near the cul-de-sac, we have no objections to the 75' centerline radius due to the lower driving speeds (less than 30 mph) that can be anticipated on this roadway at the curve. Drainage map i~ incorrect regarding the 100 year floodplain. Applicant must use 100 year ultimate discharges as originally prepared by Carl Anderson (Kimley-Horn) rather than FEMA's data in order to comply with the City's CFMO. Finish floor elevations, 100 year flood elevations and the 100 year floodplain limit line shall all be affected and may result in reclamation needing to be requested in order to develop the lots fronting Grapevine Creek. 17103 Preston Road · Suite 100 · LB 118 · Dallas, Texas 75248 · Phone 214/248-4900 e Sub-Division Ordinance requires minimum street width for a local classified street to be 28' b-b not 27' b-b as shown. e On the construction notes, sheet 3, if the plasticity index of the soil is less than 6, cement stabilization is required rather than lime treatment or a soils report can be submitted proposing an alternate design. Storm sewer hydraulic grade line needs revised to reflect proper 100 year starting elevation. Also, specify on the plans that beveled radius pipe is required for curved storm sewers. In summary, due to the unresolved floodplain issues still outstanding, we must recommend that this final plat be denied and the construction plans not be approved until all the items can be satisfactorily addressed and confirmed by the DRC staff and Floodplain Administrator. We met with the applicant on January 5, 1989 and advised them in detail regarding our concerns with the floodplain, final plat and construction plans. Please call if you have any questions. Sincerely, Kevin peiffe~. E. KP/dsp cc: File 88305