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Stantec December 8, 2010 Page 4 of 9 On November 23, 2004, an additional SVE test was conducted on monitoring well MW-2. Based on the soil vapor samples collected during the five hour test, approximately 1.8 pounds of TPHg was removed. No recordable amounts of benzene or MtBE were removed during the test. On March 15, 2005, SECOR submitted a Work Plan for 02 Sparge Well Installation to the SJCEHD. This work plan details the proposed installation of three oxygen injection wells to improve the remediation at the site. In a letter dated May 3, 2005, the SJCEHD stated that the work plan would have to be approved by the California Regional Water Quality Control Board (CRWQCB) before the SJCEHD could comment on it. The letter also directed 7-Eleven, Inc. to sample MW-4 semi-annually and MW- 4A quarterly. In response, SECOR submitted a work plan for evaluation of oxidation capacity of groundwater to the CRWQCB on July 8, 2005. The CRWQCB approved the work plan in an email dated August 9, 2005. On June 27, 2005, SECOR submitted a work plan for additional site assessment to the SJCEHD. The work plan proposed the addition of MW-8 to the west of MW-2. The work plan was approved in a letter dated July 11, 2005. On June 27, 2006, the SJCEHD approved the March 15, 2005 Work Plan for 02 Sparge Well Installation. Oxygen injection wells SP-2 and SP-3 and groundwater monitoring well MW-8, were installed on November 28 and 29, 2006. A report summarizing well installation activities was submitted to the SJCEHD on February 9, 2007. On June 1, 2008, SECOR International Inc. became Stantec Consulting Corporation (Stantec). In a letter dated July 13, 2009, the SJCEHD requested the reduction of groundwater monitoring and sampling frequency from quarterly to semi-annual and annual as required under the State Water Resources Control Board (SWRCB) Resolution 2009-0042. However, given that active remediation is being conducted at the site, 7-Eleven will continue to conduct quarterly groundwater monitoring and sampling in order to observe the effectiveness of the remediation activities. In a letter dated September 22, 2009, the SJCEHD requested the submittal of a soil vapor intrusion risk assessment. Well construction details are provided in Table 1 and historical sail analytical results are provided in Table 2. SOIL-GAS SURVEY On September 18, 2000, IT Corporation personnel supervised Precision Sampling during the installation of soil-gas survey points SG-1 through SG-11 via a truck-mounted hydraulic probe driver at the locations depicted on Figure 2. At each soil gas survey point, a hollow one inch diameter push-probe rod with an expandable tip was placed to a depth of three feet below ground surface. 19976 Vapor Risk Assessment Report.doc