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California 1pgional Water Quality Cofrol Board <br /> (\- Central Valley Region <br /> v Or <br /> Katherine Hart, Chair <br /> Linda S.Adams 11020 Sun Center Drive#200, Rancho Cordova,California 95670-6114 Arnold <br /> Secretary for Phone(916)464-3291 •FAX(916)464-4645 Schwarzenegger <br /> Environmental http://www.waterboards.ca.gov/centralvalley Governor <br /> Protection <br /> 7 September 2010 R ���� � <br /> Slit 0 <oi0 <br /> ENVInu/Vj ;r1ut <br /> Bryan Vilar PiEft jSrR��gLTy <br /> Pilkington North America, Inc. ES <br /> P.O. Box 128 <br /> Lathrop, CA 95330 <br /> QUARTERLY MONITORING REPORT COMMENTS, DIESEL LINE SPILL, <br /> PILKINGTON NORTH AMERICA, LATHROP, SAN JOAQUIN COUNTY <br /> Staff of the Central Valley Regional Water Quality Control Board (Regional Board) <br /> have reviewed the 30 June 2010 Second Quarter Groundwater Monitoring Report <br /> submitted on your behalf by Condor Earth Technologies. Pilkington North America <br /> (PNA) has been monitoring groundwater due to a release of diesel fuel (TPHd) from <br /> a fuel line in 1996. Although about 3,000 gallons of TPHd were recovered from the <br /> initial excavation, only about 200 gallons of TPHd have been recovered since that <br /> time. Light Non-Aqueous Phase Liquids (LNAPL) continue to be found in several of <br /> the on-site recovery wells. <br /> Regional Board staff reviewed previous discharges at the PNA facility and note the <br /> water table cleaned up after removal of the source. PNA has been skimming <br /> LNAPL over ten years. Although the data shows progress was made until <br /> December 2008, monitoring events since that time showed significant increase of <br /> LNAPL in MW-3. This increase may indicate that an additional source has occurred <br /> that is contributing LNAPL to the water table. PNA needs to develop a work plan to <br /> investigate whether there is an-active leak from an additional source. Also, PNA <br /> needs to determine if contaminated soil exists from the old leak that could contribute <br /> LNAPL to the water table. The Work Plan needs to contain a task to identify the <br /> current layout of all fuel lines and report all inspections and pressure tests of TPHd <br /> delivery systems. The Work Plan should be submitted by 29 October 2010. <br /> Staff appreciate PNA's cooperation regarding monitoring and recovery of the TPHd. <br /> The areal extent of the plume appears to be stable, therefore quarterly monitoring <br /> reports are no longer required at this site. From this time forward, PNA will need to <br /> monitor groundwater semi-annually (SA) in the first and third quarters to verify <br /> groundwater gradient and progress of the recovery. SA monitoring reports should <br /> be submitted no later than May 1 and November 1 of the year. Therefore, the next <br /> SA monitoring report is due 1-November 2010: Reports need to include a map <br /> showing the water table gradient, the thickness of the LNAPL and a graph showing <br /> the cumulative TPHd removed per well. We encourage PNA to continue TPHd <br /> California Environmental Protection Agency <br /> 2d Recycled Paper <br />