ARCHIVED REPORTS_QUARTERLY GROUNDWATER MONITORING AND REMEDIATION STATUS REPORT AND UPDATED SITE CONCEPTUAL MODEL 2009

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' Mr. James L. Barton April 8, 2009 ' Page 5 1Q09 TPHg Mass(pounds) 1Q09 Benzene Mass(pounds) Groundwater Mass 53 0.3 ' Soil Mass 871 0.9 Total 924 1.2 ' The spreadsheet used for calculating the remaining mass as well as the assumptions used in the estimation is included as Attachment E. The mass removed from the soil vapor extraction system during the first quarter of 2009 is presented under the Soil Vapor Extraction System Status discussion. Remediation System Update Residual dissolved concentrations of petroleum hydrocarbons beneath the Site are volatilized, extracted, ' and treated through the operation of a combined air sparge (AS) and soil vapor extraction (SVE) remediation system. Vapors from the SVE system are vented through two 1,000 pound granulated ' activated carbon (GAC) vessels prior to discharging to the atmosphere in accordance with the San Joaquin Valley Air Pollution Control District(SJVAPCD) permit to operate number N-5879-1-1. Figure 9 depicts the location of the remediation compound and a plan layout of the remediation well network. ' Soil Vapor Extraction System Status Vapor samples were collected from the influent and effluent sample ports of the SVE system on 1 January 13, February 2, and March 10, 2009. Vapor samples were collected in 1-Liter Tedlar bags and submitted for analysis under COC protocols to Air Toxics LTD. of Folsom, California. The samples were analyzed for TPHg and BTEX by modified EPA Method TO-3. Vapor samples had initially been collected ' on March 3, 2009 for analysis; however, the laboratory reported insufficient volume in the Tedlar bag. Vapor samples were recollected on March 10, 2009. The samples from March 3, 2009 were not analyzed. Results of the vapor samples, as well as a summary of the SVE system operational parameters and vapor treatment efficiencies are presented in Table 1. Data validation was performed on the vapor analyses, and the checklists are included as Attachment B. The data validation found high surrogate recoveries due to matrix interferences for each of the influent vapor samples. These qualifications do not affect the ' integrity of the data reporting. The discharge to the atmosphere, as quantified by both the mass emission rate and the TPHg concentration of the effluent, was within the limits of the SJVAPCD permit. Copies of the operation and maintenance (O&M) field sheets documenting the collection of the vapor samples are ' included in Attachment F. Copies of the certified laboratory analytical reports with COC documentation are included in Attachment G. The SVE system operated continuously between O&M visits during the first quarter 2009. During O&M visits, the SVE system may have required a system shut-down for 4 to 6 hours at a time. The SVE system was not operating for approximately two weeks at the beginning of first quarter 2009. As documented in the AECOM report dated January 12, 2009 (Quarterly Groundwater Monitoring and Remediation Status Report and Updated Site Conceptual Model For the Fourth Quarter of 2008), the adsorptive capacity of the carbon in the GAC vessels had been reached on December 15, 2008, and the SVE system was shut down ' for the remainder of fourth quarter 2008, pending a GAC change-out scheduled for early January 2009. On January 13, 2009, the GAC was replaced in both GAC vessels, and the SVE system was restarted. ' AECOM Environment AECOM