SITE INFORMATION AND CORRESPONDENCE

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Former JM Equipment - 2 - 5 February 2014 , 1245 W. Charter Way, Stockton San Joaquin County Background must to be established from a well that is not impacted by pollutants. OW-3 is within the petroleum plume so the 15 ug/L cannot be used as background. MW-7 is located outside of the plume and is appropriately listed in the draft Monitoring and Reporting Program as a background well. MW-7 at 0.17 ug/L was the 2011 established background level for hexavalent chromium. An increase of 20% would allow hexavalent chromium to reach 0.20 ug/L in compliance zone well MW-8 before the Contingency Plan would need to be implemented. Please confirm if you believe the data from MW-7 is reflective of background levels of hexavalent chromium at this Site, or if additional sampling will be conducted. If you elect to conduct additional sampling please provide a brief Work Plan for concurrence from this office to assure agreement on the plan to develop an understanding of naturally occurring metals in a revised NOI. 3. "If bromate concentrations in transition well MW-6 and compliance well MW-8 increase to greater than 12 Ng/L (20% above the MCL of 10 Ng/L), injection of hydrogen peroxide will stop and the sampling frequency for bromate in these wells will increase to quarterly." Increases in bromate concentrations may go as high as 20% above background established as <0.001 ug/L, and would allow bromate to reach 0.0012 ug/L in the compliance well MW-8. If the compliance well concentrations reach the level of 0.0012, all injections must stop and the Contingency Plan to inject high fructose corn syrup (HFCS) into the injection wells is to be implemented within six months. 4. The General Order includes a Monitoring and Reporting Program (MRP) that prescribes minimum monitoring requirements. The MRP requires sampling and analytical testing for petroleum hydrocarbon constituents and potential deleterious by-products in monitoring wells. Additions to the MRP are included in the Additional Requirements section of the Notice of Applicability (NOA). The additional requirements include the following: a. The NO[ does not list the Maximum Practical Quantitation Limit (MPQLs) for all of the MRP Table 2 listed metals analysis. You are to use the MPQLs in the table below for barium (Ba), cadmium (Cd), calcium (Ca), copper (Cu), lead (Pb), magnesium (Mg), manganese (Mn), mercury (Hg), molybdenum (Mo), and nickel (Ni) to establish background levels and for MRP groundwater monitoring. Compliance levels are based on background levels for metals up to 20% above background, not to exceed the Water Quality Objectives (WQOs). MPQL Table: MPQLs given in micrograms per Liter. Metals Ba Bromate Crs+ Cd I Ca Cu Pb Mg Mn Hg Mo Ni Compliance 0.0012 0.20 Background " <0.001 0.17 MPQL 700 0.00013 0.23 0.04 1,000 300 0.2 1,000 50 1.2 35 12 WQO 700 10 50 0.04 NA 300 0.2 NA 50 1.2 35 12 A=to be established prior to injections 1 =Action Level not to exceed WQQ 2=Action Level(no WQG) 3=MPQL utilized during the pilot study. NA=none listed b. Modifications to sampling frequency, after completion of one year of monitoring, may be directed by Central Valley Water Board staff as appropriate.