COMPLIANCE INFO_2023 DOMESTIC WELL SAMPLING - 7833 NEWCASTLE ROAD

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2 organic compounds (VOCs) may be present in the groundwater. The groundwater sample was collected in laboratory-supplied sample containers, that were filled completely, immediately capped, labeled, and placed in an ice-filled cooler. A completed chain-of-custody form identifying the sample name, date and time collected, and the analyses to be performed, accompanied the sample to Pace Analytical Environmental Services, a state of California certified laboratory located in Bakersfield, California. The analyses performed by Pace Analytical Environmental Services included VOCs by EPA Method 8260B. The laboratory report attached to this letter shows three values for each chemical compound that was analyzed: the method detection limit (MDL), the practical quantitation limit (PQL), and the result of the analysis. The MDL is the lowest concentration the laboratory can measure and the PQL is the lowest concentration that can be accurately quantified. A laboratory result of ND means the VOC was not detected at a concentration equal to or greater than the MDL. A laboratory result followed by the letter “J” is a “trace” concentration that falls between the MDL and PQL. This value is an estimate. A reported result greater than the PQL is an accurate (quantifiable) value. The laboratory reports also include the results of internal laboratory quality control tests that are performed to verify the laboratory instruments are operating within the tolerances required by the analytical method and that the sample(s) being tested are not affected by laboratory contamination. Review of the quality control test results for the samples collected from your well in September 2023, shows that the laboratory equipment was operating within its specified tolerances and that the samples were not affected by laboratory contamination. RESULTS As shown on the attached laboratory report and summarized in the following table, two VOCs were detected in the groundwater sample collected on September 13, 2023. Trichloroethene (TCE) was measured at a quantifiable concentration of 17 micrograms per liter (µg/L). TCE was detected above the state and federal Maximum Contaminant Level (MCL) of 5 µg/L. Tetrachloroethene (PCE) was detected at an estimated trace concentration of 0.34 µg/L. As shown in the following table, the concentration of PCE was below state and federal MCLs for drinking water. Analyte Units Results 9/13/23 MCL Tetrachloroethene µg/L 0.34j 5 µg/L Trichloroethene µg/L 17 5 µg/L Notes:j = Indicates an estimated value µg/L = micrograms per liter Results from water samples collected on September 13, 2023, from the effluent of the first carbon vessel (G.A.C. 1 Effluent), as well as the results from the effluent of both carbon vessels (G.A.C. 2 Effluent), did not contain concentrations of any VOCs above the PQL. The results from this sampling show that the water treatment system is effectively removing VOCs from the water supply entering the residence, as all results for VOCs in the effluent sample was non-detect.