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Sampling and Analysis Plan for Phase II Environmental Site Assessment South Pointe Property: 701, 705, 833, 855 West Weber Avenue Stockton, California Project and Data Quality Objectives May 17, 2021 Step 1 —Problem Statement The problem statement is stated previously in Section 3.1. Step 2—Study Goals The goals for the study are: (a)assess the vertical delineation of OCPs and lead in soil in select areas of the site, (b)assess the presence and distribution of VOCs in soil vapor across the site, and (c) compare collected data to applicable screening criteria to inform future grading, construction, soil management, and soil vapor mitigation practices. Step 3— Required Information The following new data inputs will be combined with existing information to assess soil and soil vapor conditions at the site. • Soil sampling. Soil samples will be collected from select areas of the site lacking vertical delineation of OCPs in soil based on the current data set. Samples will be analyzed for OCPs to assess the presence of these compounds. Soil samples will also be analyzed for total lead due to elevated concentrations previously observed across the site. • Soil vapor sampling. Passive soil vapor adsorption probes will be installed on an unbiased grid- based system across the entirety of the site. Although not providing quantitative data, this method allows assessment of relative VOC mass accumulations in subsurface soil vapor across the site. These data will be used to inform biased soil vapor collection locations which will generate quantitative data on soil vapor conditions. Step 4—Study Boundaries Spatial boundaries for soil sampling will consist of three discrete areas corresponding to portions of the site with insufficient vertical delineation of OCPs in soil. Each of these three areas measure approximately 1 00' x 100'. The passive soil vapor survey will be implemented across the entirety of the site using a 100' x 100' grid spacing. Active soil vapor sampling locations (estimated up to ten)will be discrete locations based on the findings of the passive soil vapor survey (i.e., collected from areas with highest accumulations of VOC mass observed during the passive survey). It is planned that the described sampling activities will be completed one time. Step 5—Analytical Approach (aka Project Decision Rules) Data will be compared to residential and commercial risk-based screening criteria to quantify potential human health risk under various future site use scenarios. The proposed screening level hierarchy described below. • Soil data will be compared to California Department of Toxic Substances Control Screening Levels (SLs, June 2020). Reported detections of compounds for which SLs are not established `1 Project No.: 185704833.5.3&5.4 3.2