SITE INFORMATION AND CORRESPONDENCE

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I Former Apache Plastics . 2 - 17 March 2015 2050 East Fremont Street Stockton , San Joaquin Co. AGE initially identified wells MW-5 and MW-20 for the purpose of establishing background levels of naturally occurring metals , total dissolved solids and electrical conductivity in the subsurface , which are used to set trigger levels for implementing the Contingency Plan if adverse impacts are observed as a result of the injection. After discussion with Daniel Villanueva with AGE on 2 and 3 March 2015, it was determined wells MW5 and MW-20 have both been impacted by petroleum hydrocarbons from the fuel release at this site and therefore these wells would not be representative of water quality conditions needed to establish background water quality. On 4 March 2015 we received an email proposing to use MW-4 and Stockton City Cab well MW-7 as "background" wells. MW-4 on the Apache Plastics site is reported as screened from 56 to 68 .5 feet below ground surface (bgs) . Stockton City Cab well MW-7 , on the property across East Fremont Street, is screened from 116 —121 feet bgs. According to data submitted to the State Water Board GeoTracker database , low levels of petroleum impacts were observed in wells MW-4 and MW-7 however, no petroleum hydrocarbons appear to have been detected in these wells since 2002 and 2005, respectively with one exception that 11 , 000 pg/L gasoline was reported in MW-7 in September 2013. Given the prior history of impacts in well MW-7 on the Stockton City Cab site, I believe the 11 , 000 pg/I gasoline reported in 2013 is an anomaly. Therefore we will allow use of wells MW4 and MW-7 for development of background metals, nitrate, sulfate , total dissolved solids and electrical conductivity levels and request you submit results with a modified Monitoring and Reporting Program (MRP) that identifies the trigger levels for implementing the Contingency Plan based on these data. Background sampling for metals, nitrate, sulfate, total dissolved solids and electrical conductivity in groundwater should be conducted before the . Notice of Applicability (NOA) is prepared because trigger levels for the Contingency Plan should be incorporated into the Monitoring and Reporting Program. Please submit results of background sampling from MW4 and Stockton City Cab MW4, in an Addendum by 30 May 2015. The proposed Monitoring and Reporting Program , based on Attachment C of the General Order was submitted in the NOI . Multiple rounds of communications have changed the monitoring approach for this project. Since submission of the Monitoring and Reporting Program, AGE has constructed three deep injection wells (IW-1 through IW-3) to a depth of 120 feet, two shallow-screened injection wells (IW4 and IW-5) , three shallow monitoring wells (MW-22 through MW-24) and one deep groundwater monitoring well (MW-21 ) at the site. Currently it appears AGE is proposing to use wells MW-23 , and MW-24 as shallow zone monitoring wells in the treatment zone, and MW-9 and MWA 3 as deep zone treatment zone wells . Well MW-21 is proposed as a deep zone transition zone well and MW-22 is proposed as the shallow zone transition zone well . AGE has identified wells MW-2 (shallow) , MW-8(deep) and MW- 11 (deep) as compliance zone wells. Given the limitations on the locations for installation of the new wells _ MW-21 and MW-22, these proposed transition zone wells are not located between the injection points and the compliance zone wells. Therefore, wells MW-21 and MW-22 are not suitable as transition zone wells and should be considered additional compliance zone wells in a modified Monitoring and Reporting Program . Please submit a modified Monitoring and Reporting Program in an Addendum by 30 May 2015. The injection of hydrogen peroxide may cause changes in the concentrations of metals, cations and anions , total dissolved solids , and electrical conductivity in groundwater water. AGE has been injecting various oxidants at this Site since December 2010 with the use in January 2011 of RegenOx, and from 14 August through 27 September 2013 with the injection of about 3, 120 gallons of Catalox (stabilized hydrogen peroxide and chelated iron) and 800 gallons of chelated iron injections in wells EW-1 , VEW- 1 , VEW-2 , MW-9 and MW-13. Results from these pilot studies indicate some reduction in petroleum