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1 ' CLOSURE REQUEST REPORT Manteca Unified School District 2901 East Louise Avenue 1 Lathrop, California 1.0 INTRODUCTION AND PURPOSE ' Smith Environmental Technologies Corporation has prepared this report on behalf of the Manteca Unified School District to present the results of first quarter 1996 groundwater monitoring and the information required for site closure review for the property located at 2901 East Louise Avenue, in Lathrop, California (Figure 1) This report is being submitted to the San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) and the California Regional Water Quality Control Board, Central Valley Region (CRWQCB) to satisfy the closure review requirements, as outlined by CRWQCB correspondence dated October 7, 1993 (Addendum to Appendix A of the Tri-Regional Recommendations) 2.0 QUARTERLY MONITORING First quarter 1996 groundwater monitoring was conducted on March 22, 1996, by Smith Environmental personnel On March 22, 1996 static groundwater levels were measured in the three site wells, MW-1 through MW-3, ranging from 12 15 to 13 21 feet below the tops of the well casings Locations of the monitoring wells are shown on Figure 2 A gradient map for the March 22, 1996 monitoring event is shown on Figure 3 Groundwater flow was generally to the west at a magnitude of 0 001 ft/ft Groundwater elevation data are summarized in Table 1 Groundwater samples were collected from wells MW-1, MW-2, and MW-3 on March 22, 1996 Prior to sampling, a minimum of three well casing volumes of groundwater were purged from each well All purged water was contained in labeled DOT approved drums and stored on site pending laboratory analyses Groundwater samples were collected after stabilization of pH, electrical conductivity (EC) and temperature The samples were collected using dedicated, ' disposable bailers Subsequent to collection, the samples were placed on ice, secured, and transported under chain- of-custody protocol to State-certified Argon Laboratories, in Ceres, California The water samples were analyzed for benzene, toluene, ethylbenzene and xylenes (BTEX) utilizing EPA ' method 8020, total petroleum hydrocarbons as gasoline (TPHg) using EPA method modified 8015, and total petroleum hydrocarbons as diesel (TPHd) using EPA method modified 8015 Laboratory analysis determined that no TPHd, TPHg or BTEX constituents were detected in any of the monitoring wells Analytical results are summarized in Table 2 Copies of field notes and W 194337lc1owre&c 1 BMTH 1