a(OARS). (See Attached Map)
This project overall purpose is to design and construct a large diameter conduit that will convey combined sewer overflow (CSO), along a general alignment beginning in the vicinity of I-670 and Neil Avenue, traveling south along the Scioto River to the location of the Jackson Pike Wastewater Treatment Plant. The OARS will relieve the existing OSIS, which is surcharging during wet weather events. The project will provide for the substantial reduction, in terms of flows or pollutant loads, in the discharges from Whittier Street Storm Tanks in compliance with the CSO Consent Order from the Ohio EPA.
The purpose of this Modification #2 is to complete final design engineering services that will be based upon the Design Report recommendations. The scope of the preliminary engineering was revised because the original construction concept, shallow, open-cut, twin 144" diameter sewers, was changed to a single, 18' diameter deep tunnel to be constructed in bedrock. The basis of the original scope was the recommendations of the 2005 Wet Weather Management Plan. A draft Design Report evaluating the open cut option from the Jackson Pike WWTP north to the Whittier Street Storm Tanks was completed and submitted to the City in August 2006. With the City's concurrence, a tunnel alternative was also evaluated, and a supplement to the DR was completed and submitted in September 2006. A Value Engineering Study was completed, reviewing all of the potential construction alternatives, and was submitted in October 2006. The VE Team concluded that the deep tunnel alternative was the best construction option and the City has accepted the recommendation.
The work involved with Modification #2 includes design and preparation of drawings and specifications for construction of an 18-foot diameter tunnel approximately 29,000 lineal feet in length including drop shaft connections to the Henry St. and Chestnut St. regulators, and drop shafts at Short St., Whit...
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