Brown and Caldwell Inc. 3/9/2022 Amendment 1

ATTACHMENT A SCOPE OF SERVICES Geotechnical Services Scope of Work - Design Phase The City of Everett(City) operates a water filtration plant (WFP) located at the south end of Lake Chaplain approximately 16 miles east of the City. The WFP infrastructure includes Portal 4, a flow splitting structure that conveys finished water to three transmission lines connected to City reservoirs. The City has contracted Brown and Caldwell (BC)to provide engineering services for improvements to Portal 4. This work includes rehabilitation and upgrades to the existing Portal 4 building and installation of isolation valves on transmission lines 2, 3, and 4. This document outlines the minimum requirements for conducting geotechnical investigations to determine the properties of the native soils and subsurface characteristics at the Portal 4 site as defined in Exhibit A. The results of the geotechnical investigation shall include recommendations on structural design considerations and dewatering, sheeting, excavation, and shoring recommendations during construction activities. The geotechnical consultant shall make additional evaluations and recommendations that are necessary in their professional judgment to properly characterize the site and to address project needs. A registered professional geotechnical engineer licensed in the state of Washington shall sign and seal the geotechnical report. Part 1 of 3: Project Specifics Portal 4 improvements include installation of 48-inch-diameter isolation valves and concrete vaults (either cast-in-place or precast) on transmission lines 2, 3, and 4 at the bottom of the slope located west of the Portal 4 structure (see page 1 of Exhibit A). The improvements also include installation of a security fence around the permitter of the Portal 4 building. The intent of this investigation is to determine the geotechnical design and construction considerations necessary for the installation of the isolation valves, vaults, and security fence. In addition,this geotechnical investigation is also to include a review of the slide forming on the hill side southeast of the Portal 4 structure and the City is requesting direction for any mitigation that may be necessary for managing the existing erosion and/or construction of a security fence around the Portal 4 building.The following geotechnical services will be provided by the Geotechnical Subconsultant: • Review and compile existing geotechnical reports and data for the project area including the following: o Geotechnical Report Proposed Water Filtration Plant (Gray& Osbourne Inc., 1981) o Geotechnical Engineering Services, Proposed Earth Embankment Portals 4 and 6 (GeoEngineers, 2007) • Explore and classify the subsurface soil conditions within the vicinity of the proposed valve and vault installation locations at Portal 4 (see Exhibit A pages 1 and 2). • Investigate the slide on the hill side southeast of the Portal 4 structure to inform mitigation (see keynote 3 on Exhibit A page 1). • The Consultant will plan and coordinate a geotechnical exploration program for the project in support of identifying subgrade soil and groundwater conditions that will affect the proposed improvements. The exploration program will include up to two (2) geotechnical borings (40 feet deep) at the location of the valve/vaults and one (1) geotechnical boring(60-80 feet deep) near the slide on the hill side southeast of the Portal 4 structure. A groundwater monitoring well with a standpipe piezometer will be installed in one of the borings at the location of the valve/vaults and the boring within the vicinity of the steep slope. Planning will include identification of the location of the geotechnical borings, coordination of required equipment, and utility clearance Brawn ANo Caldwell Attachment A Geotech Services SOW