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(35-03-200P isv, LLC ii d'rogeoio i� i estigttNo� r Munan fag".9 av V 0 C''a0_1n1fUX.Wit ZAIIw_we The wells were developed a minimum of 72 hours after construction in the field 1 (See Appendix C for Well Development Logs). Water levels were measured prior to development with a surge block by a qualified field technician under the supervision of a State Certified Hydrogeologist. Approximately ten (10) well volumes were removed from each of the three wells to remove fines from the well screens. The wells were purged and sampled a minimum of 48 hours after well development. Groundwater monitoring wells MW-1 and MW-3 were purged and developed until clear and no fines were evident. Some turbidity was still observed 5n MW-2 after well development and purging. A Slope Indicator water level meter was used to measure the depth to groundwater. The measurements were read to the nearest 100th of an inch. All wells were surveyed by a certified land surveyor for relative elevation and location. Each well was sampled after purging approximately three (3) saturated borehole volumes from each well, allowing the water level to recover to at least 80% of the original,static level. The purging was performed by the use of a steel bailer. Temperature, electrical conductivity, and pH were monitored during each purging, so that the three parameters are within a 10% error difference from one another, over three consecutive readings. The data was used to verify that water had been removed from well casing storage and that the well water was representative of the aquifer, prior to sampling. Water samples were collected by placing a plastic disposable check valve bailors down the center of each PVC well casing after purging. The bailor was lowered to the bottom of the well casing and pulled to the surface to be decanted from the bottom of the bailer by temporarily unplugging the check valve until water flowed freely into the glass sample container. Water samples were contained in 40- milliliter VOA vials for TPH-g, MTBE, BTEX, oxygenates, and lead scavenger analysis. The samples were labeled and stored on ice at 4 degrees centigrade a ngH delivered, under chain-of-custody procedures,to McCampbell Analytical, Inc. of Pacheco, California, a State-certified analytical laboratory. All samples were analyzed by appropriate and applicable EPA test methods. GRouNDWATER GRADIENT The groundwater gradient was measured on March 10, 2001 prior to groundwater sampling. All groundwater monitoring well locations were surveyed by a certified land surveyor for location and Top of Casing elevations(See Appendix D for Certified Lund Survey). The groundwater gradient was measured at 0.015 foot/foot to the South (See Figure 6 for Groundwater Gradient Map). LABORATORY RESULTS OF HYDROCARBONS 1m GROUNDWATER The only gasoline constituent identified in groundwater samples collected and analyzed from the three groundwater monitoring wells was 5 ppb toluene in MW-2 (See Appendix B for Laboratory Data Sheets) (See Table 11 for Hydrocarbons in Groundwater). The hydrocarbons identified in the groundwater grab sample collected from soil boring B-7 in 1998 was collected from a static water level measured at approximately 96.4 feet bgs (See Appendix A for Soil Boring Logs for 0-7) and is not considered to be representative of the concentrations which actually . exist. It is abundantly clear that the water level measured in B-7 could not be 96.4 feet since the bottom of the perched aquifer is no deeper that 86 feet bgs. fTherefore the 4.3 ppb benzene (See Appendix E for Laboratory Data Sheets for 05-03-2000 GeoSoly, LLC-• Hydrogeoiogic investigation for Munan Page 5 of i0