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downgradient and upgradient respectively, of the previously installed well& A figure showing the 4.0 FIELD ACTIVITIES proposed well locations was provided to DTSC in an email dated December 2, 2016. Following DTSC concurrence with the proposed locations,wells MW-1 and MW-3 were installed on December 9,2016. Details regarding the installation of new soil vapor probes and subsequent testing activities are provided in The five groundwater monitoring wells were sampled on a quarterly basis for one year on December 23, the following sections. The details related to technical methodologies are described in Appendix 8 2016, March 22,2017,June 6,2017,and September 14,2017. During the most recent sampling event in (Sampling and Analysis Plan; SAP) of the previously submitted and approved Sampling and Analysis September 2017,the predominant localized groundwater hydraulic gradient was relatively flat (0.003 to Workplan O.00S feet per foot[f(/ftD and to the northwest/north. Groundwater elevations ranged from 8.51 to 9.42 feet below TOC(M W-1 and MW-2,respectively). 4.1 Drilling Permits The volatile organic compounds(VOCs)temachloroethene(PCE)and trichloroethene(TCE)were detected Partner will obtain Site Mitigation Well and Boring Permits from the San Joaquin County Environmental in one well, MW-1 at concentrations of 28 and 2.8 micrograms per liter (µg/Q, respectively. The Health Department (S)CEHO) for the installation of five new monitoring points and replacement of six concentration of PCE exceeds the California Maximum Contaminant Level(MCU for PCE of 5.0 pg/L The exist�in�monitorinn wins that are damaged or with no owno ow cow SG-12,SG-13,SG-14,SG- concentration of TCE does not exceed the California MCL for TCE of 5.0 pg/L The PCE concentration in 18,and S -1-Ti )).—Partner will also obtain a Traffic Encroachment Permit from the City of Tracy for installation MW-1 (28 pgA)increased from the prior concentration in June 2017(14 pg/y. Concentrations of VOCS in of the two new monitoring points on Staten Place. groundwater monitoring wells,except for MW-1,continue to be non-detect 42 Health and Safety Plan Based on borings advanced during the pilot test and expansion of the SVE system, the underlying Partner will implement a Site-specific Health and Safety Plan with on-Site personnel involved in the project subsurface at SVE1 through SVE4 and SVE9 and SG29,SG30,and SG31 consists predominantly of moist, prior to the commencement of field activities. light brown medium-to coarse-grained sand(SP)with.some gravel from the ground surface to 1.5 to 2 feet bgs.The sand is generally underlain by moist,brown to gray brown silt to clayey silt(MU to depths ranging 4.3 Utility Clearance from 5.5 to 8.5 feet bgs.The underlying subsurface at SVES through SVE8 consists of moist,brown,clay to Partner will delineate the work area with white spray chalk and notify Underground Service Alert(USA)to sandy clay(CU from ground surface to approximately feet bgs. The clay is underlain by light brown silt clear public utility lines as required by law at least2 working days,not including the date of notification, with trace clay and sand to approximately 5.5 to 8.5 feet bgs. prortoddllingactivities. Partner will also subcontract with a private utility loatorto clear boring locations of utility lines using electromagnetic induction(EM)equipment magnetometers,ground-penetrating redar (GPR),and/or utilitytracem Additionally,the upper five feet of each boring will be manually excavated with a hand-auger. 4A Soil Gas Probe Installation 4A.1 Soli Gas Probe Loeatiens Please see Figures 3A and 38 for proposed soil gas probe locations(SG-36 through SG-39),soil gas probe replacement locations(SG-10,SG-12,SG-13,SG-14,SG-18,and SG-19),and Figure 4 for proposed soil gas probe locations(SG-40 and SG41)on Scadett Place to the south. The new soil gas probe locations were selected to evaluate the potential for vapor intrusion of PCE and other VOCs into the structure on the westem portion of the Site and in residences south of the former dry cleaning facility. 4A2 DrilGny Equipment The soil gas probes will be installed manually using a hand auger to a depth of 5-feet bgs by a State- licensed(C-S7)water well drilling contractor. Workplan for Additional Soil Vapor Investigation Workplan for AddiBoml Soil Vapor Investigation Tracy Comers Shopping Center PARTNER Tracy Comers Shopping Center PARTNER MS North Tracy Boulevard 3225 North Tracy Boulevard Tracy,Califomia 95376 Tracy,Cifiornia 95376 Febmary7,2020 February 7,2020 Pa9e4 Pages