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.� � -ter•-�. � �, � �� � �. .� �:: - � �� � <br />� � ���"�� �.t�k�!,� F�'��' �N + �, -��1 '� g'�'�rj� �:�,Z'�r"R �, ,��dh "�' ttI" ,,.+,a'mF.,a,.�,• w` :� � ..._-.�7' ��=9�`''i^r5,,^y �'^''i�„'_.,:-��"w ' <br /> 6 <br /> 3! <br /> 'I <br /> 5 <br /> Local Surface Water and Groundwater Use <br /> The City of Stockton obtains its municipal and industrial water supplies from a <br /> combination of treated surface water and groundwater supply wells located in <br /> residential areas ;r: � ar0L_:d S;::kton. According to the Stateof Ca a, <br /> Department of Water Resources well inventory records, no domestic or potable <br /> water supply wells are located within one mile of the Greyhound facility. <br /> SITE INVESTIGATION <br /> ` Soil Boring and Soil Sampling Procedures <br /> On September 16, 1991, a total of five soil borings were advanced to <br /> characterize the vertical and horizontal extent of hydrocarbon contamination at the <br /> site. Three of the borings were completed as monitoring wells at the locations <br /> shown on Figure 2. Each of the wells (Mini-I, Mir'-2 _tnd MW-3)were advanced to <br /> a depth of 55 feet. Soil borings (B-1 and B-2), not completed as wells, were <br /> terminated at 41.5 feet. All borings were advanced using 6.75-inch inside diameter <br /> (ID) hollow-stem augers. Soil samples were collected at five foot intervals using <br /> split-spoon sampling techniques (ASTM Standard D-1586). <br /> Representative soil samples in the unsaturated zone were collected in brass <br /> tubes lining the split-spoon sampler. Each sample was visually inspected for signs of <br /> staining and screened for the presence of hydrocarbon odors and the evolution of <br /> -� organic vapors with a photoionization detector (PID). Based upon PID readings, <br /> one soil sample per boring was selected for chemical analysis and sent to a State of <br /> California, Department of Health Services (7)HS), certified hazardous waste <br /> laboratory to be analyzed for benzene, toluene, ethylbenzene, and xylenes (BTEX) <br /> by EPA Method 8020 and total petroleum hydrocarbons (TPH) by the DHS/LUFI' <br /> Method (modified EPA Method 8015). <br /> V7 Soil sampling protocol consisted of capping each end of the brass tube with <br /> aluminum foil and non-reactive, plastic caps. The caps were then sealed with clear <br /> tape. A chain-of-custody record (Appendix B) accompanied each soil sample <br /> shipment from selection and preparation of the appropriate container at the <br /> laboratory, to the sample collection site in the field and back t,) the laboratory. <br /> Each sample was individually labeled, recorded in the field notebook, immediately <br /> packed in ice, sealed inside an insulated shipping container and shipped by <br /> 4 overnight courier to the laboratory. The remaining portion of the split-spoon <br /> sample was used to describe subsurface materials. Drilling logs and monitoring well <br /> construction data are presented in Appendix A. <br /> Prior to advancing each boring and between drilling locations, all downhole <br /> -a <br /> drilling equipment was decontaminated by steam cleaning. All drill cuttings, <br /> decontamination water, development water, and purge water was collected, <br /> E contained,and sealed in labeled 55 gallon drums on site. <br /> Monitoring Well Construction <br /> Monitoring wells were constructed of four-inch inside diameter ( D), threaded, <br /> flush joint, Schedule 40 PVC well screen and casing. The final depth of the borings <br /> 3 LMLISY132.21/0083 REV 0 <br />