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Connell Skaggs-CS 900416COpp~.n PUBliC MORKS April 16, 1990 Alan Ratliff, City Hanager ~ Steve Goram, Director of Public Wor. Shohre Daneshmand, P.E., Acting City Engineer~ Connell Skaggs Drainage Improvement Options We have reviewed the above referenced drainage improvement options as prepared and proposed byConnellDevelopment,s Engineer and have the following comments. Option %1, Construction of a 10' x 8' box culvert is the best alternative based on staff's review and recommendation. As an enclosed system, if built, it would be adequately installed in the existing 20' drainage easements with minimal maintenance needed. Please note that per the agreement between Skyhawk Venture/Connell Skaggs Development Co. and the City of Coppell, dated Dec. 11, 1988, there is a cap on the funds available in the amount of $$45,000.00. Due to trench safety laws, the cost of such construction has increased. Per the attached cost estimate for option %1, presently funds in the amount of $728,000.00 is required to construct this drainage system. Additionally, p/ease note that as per attached memo dated 2/14/90, Larry Jackson has indicated that we probably could require Boorhem & Hinckley to put in a box culvert just like we required Connell. Installation of 2- 4' x 12' box culvert and concrete lined channel, Option %2, is staff's second choice, which may be considered, but with the estimated total construction cost of $534,000.00, there weuld still be a limitation in availability of funds. At the present only $345,000.00 are available per agreement. Please note that staff has the following concerns on this option= ae Lack of adequate Drainage Easement (DE) in order to construct such drainage system, there would be a need for minimum of 30' D.E.. b. Existing fences would need to be moved back to accommodate for open drainage channel. c. Haintenance of such system is of a concern to staff. option #3would be a concrete lined open channel with the cost estimate of $259,130.00, from Sandy Lake Road to the High School culvert. Please note that staff would have the same concerns as listed for option #2; however, the proposed cost is $85,000 (+) less than the amount agreed upon in the agreement. Should this option be approved, staff recommends that the surplus funds ($85,000 +) be escrowed with the City for future maintenance of the channel and/or purchase of any related equipment for such maintenance. Staff along with connell Development Representative will be available at the April 24, 1990, City Council meeting to answer any questions. SGG/MSD/bb CONNELL.MSD