SITE INFORMATION AND CORRESPONDENCE

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RECEIVED Super Center Mart 17 March 2016 701 East Charter Way Stockton, San Joaquin County ENVIRONMENTAL HEALTH DEPARTMENT • Soil and groundwater have been tested for MTBE and the results reported in accordance with Health and Safety Code section 25296.15. During the most recent monitoring event, first quarter 2015, MTBE was detected in groundwater at a maximum concentration of 47 ug/L. • A nuisance, as defined by Water Code section 13050 does not exist at the site. No nuisance exists from the release at this Site. 5. The Site meets scenarios 1, 2 and 4 of the LTCP. The table below outlines the requirements for each scenario and the conditions at the Site that demonstrate how the Site meets Scenarios 1,2, and 4. Scenario Plume Distance to Closest Maximum Maximum Free Plume Length Well and Surface Benzene MTBE Product Stable to feet Water feet (ug/L (ug/L Allowed Decreasing 1 100 250 unlimited unlimited No Yes 2 250 1,000 3,000 1,000 No Yes 3 250 1,000 unlimited unlimited Yes Yes for >/_ 5 years 4 1,000 1,000 1,000 1,000 No Yes Site <100 1,560 ft= closest well, 600 47 Not Yes 1,850 ft north = Observed surface water The closest surface water is a seasonal drainage located approximately 1,850 feet north- northeast of the Site. The drainage empties into to Mormon Slough, a tributary to the San Joaquin River. The closest identified well is the inactive California Water Service well 50-01, located approximately 1,560 feet northeast of the Site. The DPE system was shut down in January 2014, and more than a year of post remedial monitoring has been conducted. Post remedial monitoring shows that currently petroleum hydrocarbons are not detected in down-gradient wells MW-4 and MW-7. Wells, located within the groundwater pollutant plume and along the leading edge of the groundwater pollution, show stable to decreasing post remedial trends. Trend graphs for wells MW-2, MW-3, MW-6 and MW-8 are included in Attachment B. The vertical extent of pollution extends to the maximum depth explored of 150 ft bgs. Concentrations in deeper screened wells, MW-81B, MW-8C, MW-8D, MW-913, MW-9C, and MW-9D, appear to be stable. A groundwater elevation contour map is included as Figure 3, and TPH-G, benzene, and MTBE iso-concentration contour maps are included as Figures 4 through 6. Comprehensive groundwater elevation data and contaminant concentration data from Site wells are presented in Tables 1 and 2. CPT data tables, figures, and cross sections are included as Attachment C.