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TC 1117 Lone Palm Avenue, Suite B <br />`lCVAModesto, CA 95351 <br /> i www.atcassociates.com <br /> 209-579-2221 <br /> ASSOCIATES i NC Fax 209-579-2225 <br /> Environmental, Geotechnical and Materials Engineers <br /> 2.0 METHODS AND PROCEDURES <br /> To evaluate the lateral extent of impacted groundwater in the shallow zone, monitoring wells <br /> MW16 and MW17 were installed off-site to the southeast at 2080 East Fremont Street. <br /> Monitoring wells MW18 and MW19 were installed off-site to the southeast at 2080 East <br /> Fremont Street to evaluate the lateral extent of impacted groundwater in the intermediate zone. <br /> Central Valley Lift Truck currently occupies the parcel located at 2080 East Fremont Street. Field <br /> activities were performed in general accordance with ATC' s Subsurface Investigation Workplan, <br /> Former Stockton City Taxi Cab Company, 2085 East Fremont Street, Stockton, California, <br /> dated, October 2, 2007. The workplan was approved by SJCEHD in a letter dated October 11 , <br /> 2007, <br /> 2_1 Drilling Activities <br /> From January 8 to 11 , 2008, an ATC geologist supervised the installation of MW16 and MW17 <br /> to approximately 60 feet bgs, and MW18 and MW19 to approximately 90 feet bgs. Gregg <br /> Drilling & Testing, Inc. , California License C57 485165, installed MW16 through MW19 <br /> utilizing a hollow stem auger drilling rig. The locations of the monitoring wells are shown on <br /> Figure 3 . <br /> The boreholes of MW16 and MW17 were logged based on soil samples collected from the <br /> boreholes at five-foot intervals from 5 feet bgs to 60 feet bgs using a stainless steel split-spoon. <br /> The borehole for MW18 was drilled within ten feet of MW16, consequently the lithology logged <br /> for MW16 is assumed to be similar for MW18 to 60 feet bgs. Lithologic characterization below <br /> 60 feet bgs was based on split-spoon samples collected at approximately 65 and 70 feet bgs, <br /> continuous samples collected from 73 .5 to 81 .5 feet bgs, and samples collected at 85 and 90 feet <br /> bgs. Soil samples were collected from the borehole of MW19 at five-foot intervals from 5 feet <br /> bgs to 70 feet bgs and continuously from 73 . 5 to 92 feet bgs. The soil samples were characterized <br /> for soil type, moisture content, and visual evidence of petroleum hydrocarbons. A photo- <br /> ionization detector (PID) was used as a fiel&screening device for the detection of petroleum <br /> hydrocarbon vapors in drill cuttings and cored samples. A field geologist logged drill cuttings <br /> and soil samples utilizing the Unified Soil Classification System. Descriptions of soil types <br /> encountered and sample collection intervals are included on the well logs contained in Appendix <br /> A. <br /> 292 Groundwater Monitoring Well Construction <br /> The monitoring wells were installed to further assess the lateral and vertical extent of petroleum <br /> hydrocarbon impact to the subsurface and to provide measurement points for the determination <br /> of groundwater flow direction and hydraulic gradient. Monitoring wells MW16 and MW17 were <br /> installed to a depth of approximately 60 feet bgs and were each constructed with approximately <br /> 40 feet (surface to 40 feet bgs) of blank 24nch diameter Schedule 40 PVC casing and <br /> S:\Enviromental\28349Veports\lnv rpt 2008.doc 3 ATC Associates Inc. P <br />