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t the boring, the borehole will be reamed, as necessary, such that there will be at least 2 inches of annular space between the borehole wall and the outside of the well casing in accordance with the California Well Standards. Monitoring wells will be constructed with 4-inch inside diameter Schedule 80 PVC blank casing and 0.020-slot, with Schedule 80 PVC screen. The screen intervals will be determined based on observations in the field but are anticipated to be approximately 10 feet in length. Filter pack will consist of No. 3 filter pack sand. Filter pack sand will extend 5 to 10 feet above the top of the well screen and will be selected based on the geologic log and depth of the well. A bentonite seal, 3 to 5 feet in thickness will be installed at the top of the filter pack. After the bentonite is hydrated, a Portland cement-grout seal will be tremmied into place in the annulus above the bentonite seal to the ground surface. Well surface completions will be constructed with a traffic-rated vault or stovepipe completion with bollards depending on the well location and property owner's preference. The well will be fitted with a lockable sanitary sealing well cap. 4.2.4 Monitoring Well Development After a minimum of 48 hours following well installation, the new monitoring wells will be developed. Development will consist of a combination of bailing, surging, and pumping. Groundwater quality parameters (temperature, pH, specific conductance, and turbidity)will be measured during purging activities. The well will be developed to remove the fine-grained materials inside the filter pack and casing, to stabilize the filter pack around the well screen, and to produce representative water samples from the water-bearing zone. 4.2.5 Monitoring Well Sampling The newly installed monitor wells will be tagged for total depth and depth to water using a water level indicator. The wells will then will be sampled using low-flow purging and sampling techniques in accordance with EPA procedures (EPA, 2017). A YSI 6920 (or equivalent) meter will be used to collect groundwater parameters, including dissolved oxygen (DO), oxidation- reduction potential (ORP), electrical conductivity (EC), pH, and temperature. The groundwater samples collected during the initial sampling event will be analyzed for the following: • • Sulfolane by APPL SOP Sulfolane; • Ethylene Dibromide and 1,2-Dibromo-3-chloropropane by Department of Health Services (DOHS) method; • Organochlorine Pesticides and Benzene Hexachloride(alpha, beta, delta and gamma) Isomers by EPA method 8081 A; • Organophosphorus Pesticides by EPA method 8141; • 2,4-Dichlorophenoxyaacetic acid and 2,4,5-Trichlorophenoxyacetic acid by EPA 8151; • Total Dissolved Solids by SM 2540C; • Sulfate, Chloride and Nitrate by EPA method 300.0; Site Characterization Work Plan 8 June 22,2018