SITE INFORMATION AND CORRESPONDENCE

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Michael Oliphant - 3 - 18 October 2012 NFAR-Former Vernalis Pump Stam ki • In October 2008 lateral and downgradient soil borings were drilled to collect soil and groundwater samples for delineation purposes. The results of TPHc and BTEX in soil were reported as ND at the method detection limits. Visually affected soil was not observed. TPHd results for groundwater samples collected from the downgradient borings were ND to low concentrations of 71 and 79 pg/L, below the screening level (100 pg/L); BTEX chemicals were not detected. Based on these results, the consultant indicated the downgradient extent of crude oil affected soil and groundwater were defined. Groundwater monitoring wells associated with the project Site were properly destroyed in May 2009. • Central Valley Regional Water Quality Control Board (Central Valley Water Board) staff concurred in a November 2008 letter to Chevron, that based on the findings soil and groundwater impacts at the Site had been delineated. Central Valley Water Board staff informed Chevron that a human health screening evaluation could be'submitted. • Outlined in SAIC's 2 September 2010 health screening evaluation report, the aggregate cancer risk for oral, dermal, and indirect inhalation exposure to onsite soils was determined to be 1 E- 06, which is equivalent to the acceptable de minimus risk of 1 E-06 (i. e., one in one million). In addition, the non-cancer health hazard for the same exposure routes was determined to be 3E- 03, which is below the acceptable non-cancer hazard level of 1. The most likely future onsite use will be for maintenance and/or commercial/industrial activities. As described in the human health screening evaluation, the residual crude oil remaining is not anticipated to pose an unacceptable health risk to future residents or commerciallindustrial worker scenario. The residual crude oil remaining at the Site will naturally degrade with time, likely over a period of years. • SAIC provided a No Further Action Required Request Report (NFAR) for closure consideration 30 March 2011. • SAIC provided a Soil and Groundwater Management Plan (SGMP), dated 13 October 2019. The SGMP describes procedures and contains the contact names and phone numbers for representatives of Chevron and the County Environmental Health Departments if future activities encounter crude oil affected soil-and/or groundwater. The SGMP serves as a guideline for Chevron to implement for the handling, reuse, and disposal of any crude oil affected soil and/or groundwater that may be encountered at the Site in the future. The SGMP provides procedures for property owners, developers, and/or maintenance firms to follow that addresses such topics as trench excavations, dewatering, and health .and safety guidelines. A copy of the SGMP was provided to owners of property projected to overlie affected soil and/or groundwater. • On 13 March 2012, Central Valley Water Board staff provided notification to the owner(s) of properties overlying and/or within 200 feet of the approximate boundary of affected soil and/or groundwater defined at the Site. The notification stated that the Central Valley Water Board was considering a No Further Action determination for the Site and requested comments be submitted within 30 days. Comments were received from a representative for the owner of a property projected to lie within the delineated area of affected soil and/or groundwater. Central Valley Water Board staff and Chevron representatives responded to the comments submitted to this office on 3 July 2012, and no additional comments were submitted. Extent defined: Yes. Estimated Residual Petroleum Mass: Unknown. With the exception of a circular area about 75 feet across, petroleum occurs primarily as degraded, low concentrations of SJV crude oil/petroleum hydrocarbons in soil at approximate depths of between 1 and 11 feet bgs to depths of 45 to 64 feet bgs. The circular area, located between the former pump house and boiler houses, contains TPH