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HomeMy WebLinkAboutPETERSON PLACE - Filed GC-GENERAL CORRESPONDENCE - 2003-11-04ANdERSON CONSUITINq ENGINEERS, INC. Civil Water Resources • Environmental September 26, 2002 Ms. Marsha Hilmes-Robinson Floodplain Administrator City of Fort Collins Utilities 700 Wood Street Fort Collins, CO 80521 RE: Floodplain Evaluation for the Peterson Townhomes (ACE Project No. COBKMCO1) Dear Marsha: On behalf of Mr. Bruce Froseth of B.K. Maxwell Co., Inc, Anderson Consulting Engineers, Inc. (ACE) has completed its evaluation of floodplain issues associated with the proposed Peterson Townhomes, to be located west of the existing house at 611 Peterson Street in Fort Collins, Colorado. This evaluation was based on the most recent floodplain mapping available for this area, namely that which is documented in the Old Town Basin Master Drainage Plan, Baseline Hydraulics, Volume III [ACE, May 13, 2002]. Based on the floodplain mapping documented in that report, the subject property is located in an approximate flood zone of no greater than one foot. As part of this evaluation, we have reviewed the "Utility Plans for the Peterson Townhomes" prepared by Loonan & Associates [dated October 8, 2001 ] and conducted a site visit to assess local conditions. (A copy of the final grading on which this evaluation was based is attached.) Based on our review of the referenced information, it is our opinion that the proposed site improvements will not create a rise in the 100-year water level. This opinion is based primarily on existing conditions associated with properties adjacent to the site. Existing obstructions including structures, fencing and landscaping would limit the effective flow path in this area primarily to the alley corridor. Considering: (a) the 56-foot setback of the proposed building from the edge of the alley, (b) the removal of two existing structures in the vicinity of the proposed building, and (c) the minimal changes in the local topography proposed for the area between the alley and the building, it appears that any impacts to 100-year water surface elevations would be negligible. In addition to potential floodplain impacts, we have also arrived at a recommended minimum finished floor elevation for the proposed building. The proposed finished floor elevation for the building, as shown on the "utility plans" is 4986.70 ft, NGVD. A careful review of the existing topography shown on the plans indicates that the highest existing ground elevation within the footprint of the proposed building is 4984.5 ft, NGVD. Using the approximate 100-year flood depth P: ICOBKMCOIICOBKMC01-LTR. WPD September 26, 1002 772 Whalers Wav, Suite 200• Fort Collins, CO. 80525 Phone: (970) 226-0126 • Fax: (970) 226-0121 - www.acewater.com Ms. Marsha Hilmes-Robinson September 26, 2002 Page Two of 1 foot and adding 18 inches of freeboard above this level, per City criteria, the recommended finished floor elevation for the proposed building is 4987.0 ft, NGVD. If you have any questions or comments concerning the information provided in this letter, or any other floodplain issue associated with this project, please do not hesitate to contact me. Sincerely, ENGINEERS, INC. Attachment cc: Mr. Bruce Froseth P. ICOBKMCOI ICOBKMCOI-LTR. WPD September 26. 2002