SITE INFORMATION AND CORRESPONDENCE_FILE 3

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Frontier Transportation, Incorporated Page 3 of 3 425 Larch Road July 18, 2013 Tracy, California 95376 since these wells may be needed to provide data at some point on the MTBE plume. Please submit a scope of work proposal that details the methods and materials to be used to destroy the wells. To be issued a well destruction permit, the proposal must address the San Joaquin County Well Standards requirements, such as: • Wells that have laboratory data from the last sampling event that demonstrate the presence of any contaminants of concern are to be destroyed by removing all the contents of the well (well casing, screen, filter pack, grout sealant); the cleared borehole is then to be sealed with neat cement from the bottom upward to a depth of three to five feet below grade. • All wells with unknown construction and/or located in an area of known or suspected area of contamination are to be destroyed by removing all the contents of the well (well casing, screen, filter pack, grout sealant); the cleared borehole is then to be sealed with neat cement from the bottom upward to a depth of three to five feet below grade. • Wells that have laboratory data from the last sampling event that report non-detectable concentrations of contaminants of concern and with acceptable laboratory detection limits, and with non-detect soil data, may be destroyed by pressure grouting from the bottom upward, while leaving the well casing in place. The top three feet or more of the well shall be drilled out with an auger that is at least one foot larger in diameter than the auger originally utilized to install the well, and the soil around the cut-off casing removed to a depth of an additional six inches below the new 'top' of the cut-off casing. The grout sealant shall spill out of the top of the well casing to form a mushroom cap seal, with at least 12 inches of neat cement grout poured 6 inches above and 6 inches below the top of the cut-off casing. • All groundwater displaced to the surface during grout installation shall be pumped out of the excavation to allow for the EHD inspection and verification that the well has been properly destroyed. Contaminated groundwater pumped out of the excavation shall be containerized for proper disposal. After the EHD has approved the well destruction scope of work proposal, you may submit an EHD Well and Boring Permit Application form, Master File Record form, and the appropriate fees. If you have any questions, please contact Vicki McCartney at (209) 468-9852, or by e-mail at vmccartney@sjcehd.com. Sincerely, ,ney�Victoria L. McCartney, REHS Nuel C. Henderson, Jr., PG Senior Registered Environmental Health Specialist Engineering Geologist c: Mr. Javad Masoudi, PE, EnviroMonitoring Services, 23011 Moulton Parkway, Suite B-14, Laguna Hills, California 92653 Mr. James L.L. Barton, PG, California Regional Water Quality Control Board Central Valley Region, 11020 Sun Center Drive, Suite 200, Rancho Cordova, California 95670