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WORK PLAN FOR ADDITIONAL SOIL VAPOR SURVEY Proposed Assessment Activities May 30, 2014 A Public Notice document for distribution to the residents of the Delta View Apartment Complex will be prepared then reviewed, and approved by the Department of Toxic Substance Control (DTSC) or RWQCB-CVR prior to distribution. 3.3 SUBSURFACE UTILITY CLEARANCE Prior to scheduled field work activities, Stantec will mark the locations of proposed shallow soil gas wells APSV-11 through APSV-17, and UPSV-8 in accordance with Underground Services Alert (USA) guidelines. Stantec will contact USA North at least 48 hours prior to the start of field work to allow USA members to mark subsurface utility locations. Additionally,Stantec will contact a private utility locator to verify the locations of marked USA member utility lines and investigate the presence of utility lines that are not owned or operated by USA members. Each borehole will be advanced using a hand auger which will also minimize the risk of damage to potential subsurface utility lines that could not be located using conventional methods. 3.4 SOIL BORINGS AND SAMPLING Based on recent and historical depth to groundwater data, the proposed soil borings will not be advanced deeper than 10 feet bgs and will likely be terminated at 5 feet bgs, depending on groundwater levels measured at the time of proposed field activities. Due to the depth proposed for each of the soil borings, the proposed soil borings will be advanced using hand auger equipment. Standard Operating Procedures (SOP) for boring and soil sampling are included in Affachment 3. Nine (9) soil borings identified as proposed vapor probes APSV-11 through APSV-17, and UPSV-7 and UPSV-8 will be advanced at the site at the approximate locations shown on Figure 1 and Figure 2.The locations of the proposed vapor probe borings were selected based on data gaps presented by the compromising of vapor wells APSV-2 and APSV-4, possibly due to water infiltration into capillary fringe pore space over the past several years or plugging of the tubing over time. In addition, the current Delta View Apartment boundary compliance soil vapor sampling points APSV-9 and APSV-10, to the west, are not considered to be representative of current soil vapor to indoor air intrusion protective measures due to the well location in a heavily trafficked parking driveway which also sits in a low spot that acts as a catchment area for surface water collection. Other factors considered in selecting the location of the soil vapor points include proximity to apartment structures, fence lines, and other potential obstructions. The final boring locations may be modified slightly in the field from the proposed locations depending on potential overhead, surface elevations, heavily irrigated landscapes, or subsurface obstructions. The proposed soil borings will be advanced with a pre-cleaned 3.0-inch diameter stainless steel hand auger. During augering, soils will be described in accordance with the Unified Soil Classification System (USCS) and monitored for volatile hydrocarbons using a photoionization detector (PID). Some soil samples will be collected from within 3.6