TIS 2023-08-07 Item 2B - Contract - S 149th & S 150th St Watermain Replacement Design and Construction Management with WSP

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EXHIBIT A SCOPE OF WORK FOR ENGINEERING SERVICES FOR S 149TH ST TO S 150TH ST WATER MAIN REPLACEMENT PROJECT PROJECT BACKGROUND AND OBJECTIVES The South 149th Street to South 150th Street Water Main Replacement project is part of an ongoing water system improvement effort by the City of Tukwila (CITY). This project is the third and final water main replacement contract in the immediate vicinity of the Macadam Road South main line. The objective of the project is to replace a leaking existing six-inch cast iron water main pipe which traverses north/south between S 149th St and S 150th St through two private properties. The CITY is also aiming to replace aging 6" Cast Iron mains in the east/west direction from Macadam Rd S at the bottom of the hill and 57th Ave S at the top. The City would prefer to remove the water, stormwater, and sewer utilities in the north/south run through the two private properties and install new connections down the hill to Macadam Rd S through the existing Southcenter Community Baptist Church parcel. However, if this option is not feasible, replacement of the existing water main near its existing position would be acceptable. See Attachment 1 for an exhibit of the proposed project improvements. The scope of work for final engineering will include the development and evaluation of two alternatives to a conceptual design level and some options for constructing the project. This effort will culminate in the selection of a preferred alternative, which will be become part of the final design as described below. PROJECT ASSUMPTIONS The following list is included to confirm the understanding between the CITY and the CONSULTANT and will be used to guide the work. Additional assumptions are provided with each specific project task. • Throughout this scope of work, it is understood that the CITY will provide the CONSULTANT with one set of consolidated review comments for each draft review round. The CONSULTANT will respond to the comments and incorporate the agreed- upon resolution into the final document(s). • Design of the project will comply with the City of Tukwila Public Works Department, Infrastructure Design and Construction Standards (2019). • Stormwater design will comply with the King County Surface Water Design Manual (2021), except as modified in Section 5.0.1 of the City of Tukwila Public Works Department, Infrastructure Design and Construction Standards (2019). • Utility relocation and reconstruction plans for power, gas, and communication purveyors will be prepared by the respective utility if required. The CONSULTANT will coordinate directly with the utility companies and the CITY. • Effort has been included in this scope for the relocation of the stormwater and sewer lines through the Southcenter Community Baptist Church property with the understanding this City of Tukwila S 149th St to S 150th St Water Main Replacement WSP, 202311491 Tukwila, Washington July 20p Page i of iii