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�fa0 IM�1�� CM* J111 JACOBS South Platte Interceptor Technical Memorandum TO: Craig Tessmer, Rick Anderson, DATE: June 12, 2013 Marc Pedrucci (Adams County) FROM: Jill Crockett, P.E (Jacobs), Bob Neal, P.E. (MWRD) SUBJECT: Spoils Delivery for South Platte Interceptor PROJECT NO: PAR 1088 Construction — J une 2013 U PDATE As a condition of the December 2010 Intergovernmental Agreement (IGA) between Adams County and the Metro Wastewater Reclamation District (Metro District), the Metro District is required to provide up to 75,000 cubic yards of trench spoils to Adams County at the Debetz Pit from the construction of the South Platte Interceptor (SP 1) and Effluent Pump -Back Force Main (EPB). The EPB component of the project was subsequently cancelled in December 2012, based on Water Court approval of an effluent trade between Aurora and Thornton. Also subsequent to the IGA, Adams County requested information regarding the quality, quantity and timing of the spoils delivery to assist in resource planning. The Metro District has agreed to provide this information to the extent that it is known and update it throughout the design and construction process. On January 22, 2013, representatives of the Metro District met with County staff to discuss the timing for spoils delivery. At that time, spoils production from SPI construction was expected to commence in early fall 2013 and the County committed to taking spoils by October 1, 2013. This memorandum is intended to update those versions previously provided to the County. On May 7, 2013, bids were received for the SPI project from the four prequalified bidders. Western Summit (WSCI) was the apparent low bidder, and the Metro District anticipates entering into a contract with WSCI in July 2013. This update reflects the "Issued for Bid" design documents and WSCI's preliminary construction schedule. The Metro District has estimated spoils volumes for the project based on these documents. The Metro District will continue to provide revisions to Adams County as the construction schedule is updated to keep you apprised of the most up -to -date information. The spoils delivery schedule is constrained by the project notice to proceed (July 2013) and substantial construction completion date (October 2015). The preliminary construction schedule shows excavation work anticipated to produce spoils complete by September 2014. Pipeline production rates used in determining the amount of spoils perweek have been determined based upon the preliminary construction schedule issued by WSCI. The volume of spoil produced per linear foot of pipe installed has been estimated based upon the trench cross sections in the design drawings. The preliminary project delivery schedule and soil volume assumptions have been combined to determine the minimum and maximum loose cubic yards that are anticipated to be available for delivery per week in a given month. The average of these is multiplied by the weeks in the month to arrive at a cumulative average volume that can be expected to be delivered over the life of the project. These values are shown in Table 1.