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Californi- Regional Water Quality C rol Board <br /> Central Valley Region ° <br /> Katherine Hart, Chair <br /> 11020 Sun Center Drive,#200,Rancho Cordova,California 95670-6114 <br /> Matthew Rodriquez (916)464-3291 •FAX(916)464-4645 Edmund G.Brown Jr. <br /> Secretaryfor http://www.waterboards.ca.gov/centralvalley Governor <br /> Environmental Protection <br /> TO: Duncan A. Austin, P. E. FROM: Amy Terrell,- <br /> Site and Groundwater Cleanup <br /> Pro 'ipm Manager j <br /> SIGNAT .i <br /> Steven W. Me�pks, P <br /> ry - . <br /> DATE: 25 January 2012 SIGNATURE: �� <br /> SUBJECT: RATIONALE FOR CONSIDERING NO FURTHER ACTION AT TRINKLE AND <br /> BOYS FLYING SERVICE, 31244 S. HWY 33, SAN JOAQUIN COUNTY <br /> Rationale: Residual soil contamination concentrations are below human health protective <br /> screening levels, based on California Human Health Screening Levels (CHHSLs) for <br /> residential land uses and Environmental Protection Agency Preliminary Remediation Goals <br /> (PRGs) for residential land uses. Pollutants identified in grab groundwater samples that <br /> exceeded water quality objectives (dichlorobenzene and diuron) were not detected in four <br /> quarters of groundwater monitoring. <br /> Issues: The site has been an airstrip and operations area for aerial pesticide applicators from <br /> 1949 to 2001, when the current owners purchased the property. In 1986, pesticides were <br /> detected in a wastewater discharge area, and in 1987 and 1989, Cleanup and Abatement <br /> Orders requiring investigation were issued to different operators. In 1989, three <br /> underground fuel tanks were removed without permits. In 1990, Trinkle and Boys <br /> conducted an investigation and the Cleanup and Abatement Orders were rescinded. In <br /> 1992 one more underground fuel tank was removed without a permit, although San <br /> Joaquin County concurred that confirmation samples showed that no pollution occurred <br /> relating to this tank. <br /> Setting: A small aircraft landing strip in a formerly agricultural area currently undergoing large <br /> lot residential development. Photographs of the property are found in Figure 1. <br /> Source: Discharge from airplane washwater and pesticide handling operations. <br /> Actions: Soil and groundwater investigations occurred in 1989, 2008, and 2009. Locations of <br /> the soil and groundwater samples are shown in Figure 2. <br /> • In 1989, soil samples from the operations area contained DDT, and soil samples from <br /> the drain and rinse basin contained endosulfan, parathion, and carbamates. One <br /> monitoring well, in the operations area, contained 2,4,5-T and carbamates, all <br /> substantially below water quality objectives. <br /> California Environmental Protection Agency <br /> Ca Recycled Paper <br />