SITE INFORMATION AND CORRESPONDENCE_FILE 3

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Frontier Transportation, Incorporated 425 Larch Road Page 2 of 3 Tracy, California 95376 July 18, 2013 • Based on analytical results from groundwater samples collected from the upper and lower sections of wells during the water pumping test, design and implement a groundwater pumping system using impacted wells MW3R and DPE3 to remediate methyl tertiary-butyl ether(MTBE)-impacted groundwater; • Destruction of thirteen of the twenty-eight monitoring wells associated with this site since "the data indicate that further monitoring of certain wells would not be necessary". Although the information and proposals presented in the work plan were discussed and generally agreed upon during the June meeting, the EHD does not approve the proposals as submitted in the work plan largely because the proposals lack specificity; please resubmit the work plan to the EHD by 29 August 2013 with the following additions: • Provide cross sections based on boring logs to demonstrate soil lithology near the source area where the former gasoline USTs were located to justify the need to perform a groundwater pumping test; • Provide diagrams of the inflation packer, demonstrating how the inflation packer, inserted into the well casing at approximately thirteen feet bsg, will isolate groundwater from the upper and lower sections of the well; and • Identify what wells will be used in the groundwater pumping test, the purge volume to be removed before sampling each section of the well, and the groundwater sampling technique used to collect groundwater from the two zones. The EHD will not comment on the proposal to implement groundwater pumping at this site until the information requested above has been submitted and the findings from the pumping test have been submitted to this agency. Please note that a work plan to install a groundwater Pumping remediation system must include the method of waste water disposal and if oxidation enhancement of the groundwater pumping system is proposed in future work plans, a comparison of several remedial methods must be provided to demonstrate it as the most cost- effective method. To this end, the EHD suggests that you contact the Central Valley Regional Water Quality Control Board for information concerning Notice of Intent to comply with the terms of General Waste Discharge Requirements, and the Monitoring and Reporting Program No. R5- 2008-0149-010. As the EHD mentioned during the meeting on 26 June 2013, it is more cost effective to destroy all of the monitoring and remediation wells at one time when the site is ready to close thereby minimizing costs for work plans, reports, mobilization of drilling crews and necessary field staff. The monitoring costs can be minimized at this time by removal of the wells in question from the monitoring program, which the EHD will approve with any additional monitoring of the wells to be required only if justified by site conditions. The EHD acknowledges that there is some risk to groundwater associated with each monitoring well, which you as the owners have assumed. Ordinarily, the EHD has monitoring wells destroyed when no longer needed, but as monies are limited for this site, you can choose to delay the well destructions. This noted, the EHD will approve the destruction of eight of the thirteen monitoring wells proposed by EMS in the work plan, specifically: MW-6, MW-7, MW-10 through MW-12, and MW-14 through MW-16. The EHD does not approve the destruction of MW-5, MW-13, MW-18, MW-25 and MW-26 at this time