SITE INFORMATION AND CORRESPONDENCE

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Tri-Ag Services, Inc. 2 - June 12, 2017 A public health goal (PHG) for 1,2,3-TCP was developed by the Office of Environmental Health Hazard Assessment (OEHHA) for use by the State Water Board to establish an MCL. This PHG represents the level of 1,2,3-TCP in drinking water that does not pose a significant risk to health over a lifetime of exposure (70 years).The PHG for 1,2,3-TOP is 0.0007 pg/L, or 0.7 parts per trillion (ppt). The MCL for 1,2-DCP has been set at 5 pg/L. The last documented level of 4.0 pg/L for 1,2,3-TOP in the Tri-Ag domestic well exceeds the above referenced screening level of 0.0007 pg/L by approximately 10,000 times. The last documented level of 49 pg/L for 1,2-DCP in the Tri-Ag domestic well exceeds the above referenced screening level of 5 pg/L by approximately 10 times. Comments Based on the 2004 sampling results from the Tri-Ag domestic well, there is a potential for exposure to the above referenced chemicals of concern via drinking water and represents a risk to human health and the environment. To determine if the current levels in the Tri-Ag domestic well still represent a risk, Central Valley Water Board staff requires the domestic well be sampled for nitrates, 1,2,3-TOP, and 1,2-DCP. A report detailing the sample results must be submitted to this office by July 28, 2017. To expedite the process, Central Valley Water Board staff are willing to complete the sampling for the property owners if onsite access for this one-time event is provided. DDT, Dieldrin, and Oryzalin were detected in some soil samples. Central Valley Water Board staff requires these constituents be included in the domestic well sampling analysis to determine if these chemicals of concern have leached to groundwater and migrated to the domestic well. This requirement for a report is made pursuant to Water Code Section 13267, which allows the Regional Water Board to require technical or monitoring program reports from any person who has discharged, discharges, proposes to discharge, or is suspected of discharging waste that could affect water quality. The attachment provides additional information about Section 13267 requirements. Any extension in the above deadline must be confirmed in writing by Central Valley Water Board staff. In addition to a hard copy you are also required to submit all documents in electronic format to the State Water Resources Control Board's GeoTracker database pursuant to the California Code of Regulations (Title 23, Section 3890 et.seq.). Guidance for electronic information submittal is available at: http://www.waterboards.ca.goviwater_issues/programs/ust/electronic_subm Please note that this requirement includes all analytical data, monitoring well latitudes, longitudes, elevations, water depth, site maps, and boring logs (PDF format).