Brown and Caldwell, Inc. 9/20/2023

PGSF WMVD Storm and Combined Sewer Design Scope of Work 08-25-2023 14 of 41 Category 2: Sensitive information Category 2: For official use only / disclosure permissible by law. with seasonal groundwater variations across the site. No environmental groundwater monitoring wells will be installed as part of the environmental investigation portion of this scope of services. • Evaluate Geotechnical Field and Laboratory Data: Based on the borings and the laboratory test results on selected samples, HWA will generate estimates of the soil strength and other properties needed to evaluate the effects the subsurface conditions will have on the proposed improvements. • Evaluate Environmental Field and Laboratory Data: Based on the environmental laboratory soil and groundwater analytical results, HWA will provide generic recommendations for dealing with potentially contaminated soil and groundwater during construction. Experience has shown that subsurface soil and groundwater conditions can vary significantly over small distances, and it is possible that other subsurface conditions and/or contamination may exist in areas that were not investigated. Based on the size of the project area, the proposed number of geotechnical borings will likely not be sufficient to investigate the entire project area and additional environmental investigation may be recommended for future phases of design. The limited testing performed under this scope will be primarily for disposal of IDW. If contamination is discovered, it is likely that the data will not be sufficient for delineating the vertical and/or lateral extent of contamination or to provide an accurate cost estimate for soil and/or groundwater disposal during construction. • Develop Geologic Cross-Sections: HWA will construct geologic cross-sections, as needed, for the project. These cross sections will show near surface soil conditions and will be provided in a geotechnical report. • Generate Seismic Design Parameters: Based on the soils encountered along the alignment, HWA will determine the Site Class for seismic design. The design spectral acceleration parameters will then be selected in accordance with the governing codes. • Evaluate Liquefaction Potential: HWA will evaluate the susceptibility of the subsurface soils to liquefaction along the corridor and assess the potential impacts to the proposed improvements. • Evaluate Consolidation Potential: HWA will evaluate the susceptibility of the subsurface soils to consolidation settlement along the project corridor and will assess the potential impacts to the proposed improvements. If consolidation settlement is found to be a design consideration, HWA will evaluate potential mitigation options. • Provide Trenching Recommendations: HWA will provide trenching recommendations including excavation, subgrade preparation, backfill material, placement, and backfill. • Provide Trenchless Recommendations: HWA will provide general trenchless recommendations to assist with the design of the trenchless methodology. Trenchless design will be performed by others. • Hydraulic conductivity: HWA will conduct grain size analysis screening to develop general recommendations for construction dewatering. Hydraulic conductivity will be estimated using grain size distribution. Field measurement of hydraulic conductivity/flow rate is not included in this scope of work. • Provide Lateral Earth Pressure Recommendations: HWA will provide lateral earth pressure recommendations for temporary shoring and permanent below grade structures. • Prepare Draft Geotechnical Engineering Report: HWA will prepare a draft geotechnical engineering report for the project. This report will contain the results of the explorations and testing including descriptions of surface and subsurface conditions; a site plan showing