ARCHIVED REPORTS_XR0007375 CASE 2

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AT&T -Lodi ATC Prosect No 75 75128 0001 Page 3, January 14, 2001 morutonng well locations are depicted in Figure 2 An ATC geologist maintained a continuous log of the soils penetrated and noted soil type, color, and obvious discoloration Soils were classified in accordance with the Urufied Soil Classification System (USCS) The geologic log of bonngs are presented in Appendix B A Public Health Services, San Joaquin County, Environmental Health Division (SJCEHD) permit numbered 50024668 and dated November 27, 2000, was issued for installation of the above- referenced wells A copy of this permit is presented in Appendix A The monitoring wells were drilled and installed on December 13, 2000 Mr Harlan Knoll of the SJCEHD, observed boring and grouting procedures ' Relatively undisturbed soil samples were collected in each boring at approximately 5-foot intervals of depth using a California modified split spoon sampler The sampler was driven 18 inches ahead of the drill bit using a 140-pound hammer with a 30-inch drop The number of blows necessary to drive the sampler was recorded on the boring logs as a qualitative measure of the soil's characteristics The split spoon sampler was fitted with 6-inch long, 2 5-inch diameter brass sleeves Upon retrieval of the sampler from the borehole, soils were screened for orgaruc vapor envssions using an OVM portable photoionization detector (PID) Representative portions of the sample were transferred into plastic ziplock bags and then monitored for peak readings while manually disturbing the soil Organic vapor emissions were recorded in volumetric parts per million (ppm) Samples were not submitted for laboratory analysis Before advancing each boring, the downhole drilling equipment (auger sections) was steam cleaned to prevent cross-contamination from the previous borings Sampling equipment was cleaned between uses by washing in a Liqui-Nox detergent solution followed by rinsing first with tap water and then with distilled water Excess soil cuttings and rinsate generated by steam cleaning and sampling operations were placed in 55-gallon DOT approved steel drums Final disposition of the drill cuttings and rinsate will be determined, based in part, on soil and groundwater sample analyses 4.3 GROUNDWATER MONITORING WELLS 4.3 1 WELL INSTALLATION Three (3) groundwater monitoring wells designated MW 1 through MW3 were installed in the viciruty of the former underground storage tank location (Figure 2) Each well was constructed using a 2-inch diameter, Schedule 40, flush threaded PVC casing and screen The screen and casing were pre-cleaned and were stored in plastic wrappers before insertion in the borehole Screened PVC with 0 010-inch horizontal slots was installed from a depth of approximately 38 to 18 feet bgs (approximately 10-feet above the water table and ten feet below) Blank PVC casing was attached to the slotted PVC which was extend to the surface The annular space around the well screen was filled with pre-washed No I2/12 Monterey sand from the base of the boring to approximately 2 feet above the top of the well screen The sand pack was manually surged with a vented surge tool and approximately 3 feet of hydrated bentonite was placed above it The remaining annular space to the ground surface was backfilled with a neat cement grout The wells were each completed with a locking well cap and finished to grade in a traffic-rated monument box Well construction details are presented in Appendix B