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r .r commencement of the subsurface excavations as required by law. The services of a private utility locating company will also be obtained to further attempt to delineate subsurface utilities and conduits in proximity to the proposed boring and trenching locations. • Obtain well construction permits from the SJCEHD and pay requisite fees prior to initiating drilling and well construction. r • Contact the City of Stockton and the San Joaquin County Building Departments and obtain a Commercial Building Permit (if necessary) for the construction of the AS/SVE system and associated security enclosure. •� • Contact Pacific Gas and Electric to supply temporary power to the remediation system. • Retain the services of a Caltrans-approved and California C57-licensed subcontractor to perform the drilling and well installation activities. r • Retain the services of a Caltrans-approved and California-certified analytical laboratory to perform the analyses of soil and groundwater samples. v Field Activities .. AS Well Installation Seven hollow-stem auger (HSA) soil borings will be advanced and converted into 2-inch-diameter AS wells. The proposed locations for the AS wells are depicted on Figure 2. Seven soil borings will be advanced to depths between 45 and 55 feet using a HSA drill rig. Relatively r undisturbed soil samples will be obtained at 5-foot intervals, using a 2-inch-diameter by 18-inch-long split spoon sampler equipped with three 6-inch-long sampling tubes. Upon retrieval of the sampler, the least disturbed sample tube will be secured with Teflon sheets and plastic end caps, labeled, chilled and placed in a cooler for subsequent delivery to the analytical laboratory following chain-of-custody r protocol. Each AS well will be constructed using 2-inch-diameter Schedule 40 poly-vinyl-chloride (PVC) well casing and perforated screen. The well screen will consist of a 5-foot section of 0.020-inch-slotted screen placed approximately one half foot off the bottom of the boring between depths of 45 and 55 feet in order to impact the finer-grained soils located at these depths. A filter pack consisting of#2/12 silica or equivalent sand will be placed from the bottom of the boring to approximately 2 feet above the top of the well screen. A well seal consisting of at least 5 feet of bentonite pellets will be placed above the filter pack. The remaining annular space will be grouted to the surface with a Portland �+ cement/bentonite slurry and the well secured with ari 12-inch-diameter, traffic-rated well box set in concrete. Per AMEC's recommendations, the AS wells will be spaced from each other at a distance of approximately 20 feet on center. A typical AS well construction detail is included on Figure 5. r The soil borings will be logged in the field following the Unified Soil Classification System under the direction of a California Professional Geologist. Soil samples will be field screened with a photo- ., ionization detector (PID) to obtain representative qualitative indicators of the presence of volatile organic vapors in the pore space of soil samples collected. The PID readings recorded in the field will be presented on the boring logs. mod r Stockton Maintenance Station,Task Order No.05 Caltrans Contract No.06AI 141,EA 10-ON8300 Project No.S9200-06-05A -4- December 28,2010 r