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6.3 Dissolved-Phase Hydrocarbon Plume is Stable It has been clearly established that the dissolved-phase MTBE plumes in groundwater beneath the site are laterally and vertically characterized. In addition, lognormal graphs of MTBE concentrations over time with first order rate equations and trendlines for MTBE also clearly indicate the MTBE is degrading and naturally attenuating. The exception to this is well MW- 13A/B in which MTBE concentrations appear stable to slightly increasing. Based on these graphs and results of modeling (see Section 5.0 for additional information), MTBE concentrations in groundwater are projected to meet the secondary MCL for MTBE (5.0 gg/L) through natural attenuation, on average, in the year 2011 (but in worst case in the year 2018 for MW-13A/B and 2019 for MWO-lx). 6.4 Sensitive Receptors & Water Wells Not Likely to be Impacted A 2,000-foot radius sensitive receptor survey was conducted (see Section 2.3 for additional information). Based on DWR information and a physical search of the area, no domestic or commercial wells were identified. In addition, no surficial water bodies are located within the 2000-foot survey radius. 6.5 No Significant Risk to Human Health or Environment Based on the minimal nature and location of impacted soil and the distribution and extent of MTBE-impacted groundwater beneath the Site and site vicinity, the current and future planned commercial use of the property, and the lack of nearby water supply wells or sensitive human populations, the only exposure pathway that appears complete or potentially complete is inhalation of vapors emanating from impacted soil and/or groundwater. Those receptors to this potential inhalation risk are on-site commercial workers or customers at the Joe's Truck property or the adjacent Storage-Pro Facility. In August 2009, a soil gas survey was conducted to evaluate this pathway (see Section 4.0 for additional information). A comparison of the results against RWQCB-SF's Screening.for Environmental Concerns at Sites with Contaminated Soil and Groundwater — INTERIM FINAL - November 2007 (Revised May 2008), Table E-2 (Shallow Soil Gas Screening Levels for Evaluation of Potential Vapor Intrusion Concerns) using the residential values indicate that ESLs were not exceeded for any chemical analyte. Given these results, the potential risk for vapor intrusion concerns at the site and in areas surrounding the site above the residual impacted groundwater appears low. 6.6 Request for Regulatory Case Closure / No Further Action Based on the information presented herein, on behalf of Mr. Dalwinder Dhoot, Stratus respectfully requests that the SJCEHD and RWQCB-CV grant regulatory case closure / no further action (NFA) related to the historical hydrocarbon release at the 15600 S. Harlan Road property. Once concurrence with this request is received, Stratus will permit and destroy all groundwater monitoring and extraction wells that have been installed in association with the property in accordance with SJCEHD regulations and well standards, complete and submit California DWR well completion reports certifying the destruction of the wells, remove all remaining waste from the site, and prepare and submit a well destruction report to SJCEHD. Page 24 STRATUS