2011-385 AMS - McGill Associates, P.A. - design of McGowan Creek Gravity Sewer Interceptor

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Mr. Craig Benedict October 20, 2011 Page 2 Survev ^ Prepare a routing survey of the proposed gravity sewer interceptor from the existing McGowan PS to the proposed Brookhollow PS. Survey will include pertinent data for preparation of design plans for the proposed sewers, along with any available property line information for future preparation of easements. ^ Verify vertical and horizontal control consistency with current project plans. ^ Verify critical force main routing elevations for pumping from the Brookhollow PS to Hillsborough and Mebane, utilizing GPS technology. McGowan Interceptor Preliminarv Design ^ Utilizing field survey, prepare a routing of the proposed sewers, and review routing with the OWNER to verify acceptance and compliance with applicable County regulations. ^ Prepare a profile of the proposed sewers to determine needed depth at the Brookhollow PS. ^ Prepare a preliminary opinion of cost for the proposed sewer interceptor. Broolchollow PS Analysis and Redesignn ^ Based on current and proposed service areas contributory to the proposed pump station, prepare design calculations for pumping capacity and storage volume needed to modify the pump station. ^ Discuss with OWNER routing options for directing flow from the proposed pump station to the City of Mebane in the future. Evaluate the feasibility of these options, and develop order of magnitude preliminary cost estimates and electricity requirements for the feasible options. o Prepare pumping system head calculations for each of three (3) force main routing options; 1) current project PS capacity flowing to the McGowan PS with increased wetwell depth, 2) all proposed Efland flows to Hillsborough, and 3)all proposed Efland flows to Mebane. ^ Based on system head calculations, recommend pump conditions for the force main options and recommend initial pump selection to easily be modified to meet future desired ' - conditions. ^ Prepare revised electrical design to accommodate future pump conditions.