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REQUEST FOR DRAINAGE COMMITTEE AGENDA ITEM <br />Agenda Date Requested: July 9, 2018 <br />Requested By: Lorenzo Wingate <br />Department: Public Works <br />Report: w " Resolution: (D Ordinance:( <br />Exhibits: <br />Appropriation <br />Source of Funds: <br />Account Number: <br />Amount Budgeted: <br />Amount Requested: <br />Budgeted Item: y " YES (D NO <br />SUMMARY <br />Harris County Flood Control District's (HCFCD) F101-06-00 Channel system conveys storm water runoff from the <br />Lomaxarea and ultimately outfalls into Lower San Jacinto Bay. The downstream section of the channel has been <br />improved to ultimate capacity. An existing pipeline corridor, containing several pipelines located at depths ranging <br />fromapproxixrutely 2'to 18', cross the channel, limiting the depth of potential channel improvements. <br />Moderate/heavy rain events, compounded with backwater conditions from this section of the channel, contributes to <br />wide -spread flooding within the LomaxArea. <br />Harris County Flood Control staff has informed Public Works staff that survey data has been collected on this most <br />upstream section. Construction drawings are being prepared in-house, by HCFCD staff, to provide direction on <br />clearing overgrowth, trees, and obstructions; minor erosion control and slope stabilization; and desilting. <br />Construction is projected to begin late 4th quarter 2018 or early 1st quarter 2019 (calendar year). <br />A high level delineation by KSA found the watershed to be about 310 acres, versus the 583 acres used in the 1987 <br />masterplan. Unit F101-06-00 has a capacity of less than 200 cfs, currently, before it rises out of its banks. <br />The following options were included within the preliminary draft of the feasibility study prepared by KSA: <br />1) Full excavation of existing 60-ft ROW to construct a concrete channel that will maximize capacity of current ROW, <br />providing approximately 700 cfs, without deepening the channel ($2.4M). <br />2) Construct concrete channel from Valley View to the existing drop structure; widen the channel beyond the ROW <br />to convey the 100-year event (1,326 cfs) by maintaining existing flow line of the channel ($3.2M). <br />3) Construct concrete channel from Valley View to the pipeline corridor and deepen the existing grass lined channel, <br />by one foot, fromthe pipeline corridor to the existing drop structure. ($1.5M). <br />Action Re quire d: <br />Approved for Drainage Committee Agenda <br />Corby D. Alexander, City Manager Date <br />