WORK PLANS - Laserfiche WebLink

Home Browse Search

Sampling Plan - 7 - 25 March 2022 Stockton Propeller, Inc. 2478 Wilcox Road, Stockton COMMENT 10 Issue: Section 3, Sensitive Receptors, states SPI has not identified any sensitive receptors (surface waters, municipal supply wells, and domestic wells) within one (1) mile of the facility. The SAP states the United States Geological Survey (USGS) National Water Information System Mapper was used to make this determination. A more applicable resource to identify municipal supply, production, and domestic wells is the Department of Water Resources (DWR) Well Completion Report Map (https://www.arcgis.com/apps/webappviewer/index.html?id=l 81078580a214c0986e2da28f8623 b37). Central Valley Water Board staff reviewed the DWR website and identified several sensitive receptors within a one-mile radius of the Site. Requested Action: Please reevaluate the sensitive receptors within a one-mile radius of the Site and update the information in the revised SAP. COMMENT 11 Issue: Section 4.1, Strategy, neglects to state how many soil boreholes will be drilled. However, Attachment G presents a map showing six (6) borehole locations. It is unclear if all six (6) boreholes will be drilled and sampled. Additionally, Section 4.1 proposes to collect soil samples at five (5), 10, and 15 feet below the ground surface (bgs) in each borehole. The depth and the condition of the septic tank are unknown. The DTSC classified sample SP-03 as corrosive, and this sample was collected from a container that is normally disposed into the on-Site septic system. Therefore, the soils surrounding the septic tank may be impacted if the septic tank walls have been damaged or compromised. Requested Action: In the revised SAP, please clarify how many boreholes surrounding the septic tank will be drilled to collect soil samples. Central Valley Water Board staff suggest evaluating the condition of the septic tank once the contents are removed. If any of the walls of the tank are damaged or compromised, please collect soil samples outside of the impacted wall at every five (5) feet bgs up to 15 feet below the bottom depth of the septic tank. For example, if the bottom of the septic tank is 10 feet bgs and the west wall is corroded, thus, allowing the contents of the septic tank to be in contact with the surrounding soils, then soil samples should be collected outside of the west wall at every five (5) feet bgs interval up to 25 feet bgs. Additionally, if the bottom of the septic tank is damaged or compromised, then Central Valley Water Board staff recommend at least one boring be taken as close as possible to the damaged area underneath the tank using a slant boring or other appropriate method to sample underneath the septic tank. If the walls of the septic tank are intact, then one (1) boring outside of each wall collecting samples at five (5), 10, and 15 feet bgs is sufficient.