March 19, 2014 IV. Special Report – A) TBI Drainage Improvements at Cottage and Farrington Feasibility Study Report (Eleria)
DATE: TO: FROM: RE:
March 12, 2014 CRWD Board of Managers Anna Eleria, Water Resource Project Manager TBI Drainage Improvements at Cottage Ave. and Farrington St - Feasibility Study Report
Background In late 2011, CRWD staff was first made aware of a local flooding problem in the backyard of 300 Cottage Avenue West, which is adjacent to CRWD’s Trout Brook Storm Sewer Interceptor. This area receives runoff from its own property and neighboring properties to the east and from multi-family properties and BNSF right-of-way to the west. The existing flared inlet to TBI, which is upstream and west of the affected property, is undersized and improperly designed. The flared inlet frequently was blocked with organic debris and trash after a rainstorm and stormwater runoff bypassed the inlet and the associated berm and flowed into and ponded in the backyard of 300 Cottage Avenue. For a year and a half, CRWD staff conducted frequent minor maintenance work to improve drainage to the existing inlet. Issues In 2013, CRWD approached the localized flooding issue in two ways. First, CRWD hired a contractor in late summer 2013 to conduct more significant maintenance work that included clearing sediment, trash and debris from the area around the inlet, grading work in the ditch upstream of the inlet, and repairing and raising the berm. Based on follow-up inspections, the inlet has remained clear and open helping to ensure runoff from the west flows into TBI inlet. The work eliminated the need for CRWD staff to conduct any minor maintenance work last fall. Second, CRWD commenced a feasibility study to better understand the issue, evaluate its cause(s) and identify potential long-term solutions. The feasibility study, conducted by Barr Engineering, included field investigations, detailed modeling, and evaluation of flood mitigation alternatives including volumereduction/water quality improvement strategies. The draft feasibility report has been completed and is enclosed for the Board’s review and comment including a recommendation on the preferred alternative. Barr Engineering staff will present the draft feasibility report and CRWD staff will share comments received from the CAC who heard the presentation at their March meeting. Action Requested None required, for your review and comment including a recommendation on preferred alternative for drainage improvements at TBI Cottage Ave. and Farrington St. enc:
TBI Drainage Improvements at Cottage Ave. and Farrington St. - Feasibility Study Report
W:\06 Projects\Trout Brook Interceptor\TBI Farrington-Cottage\Board Memos\BM TBI Farrington Feasibility Study Report 03-19-14.docx
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