SITE INFORMATION AND CORRESPONDENCE_PRE 2019

Home Browse Search

Stantec April 30, 2010 Page 9 of 14 Reference: First Quarter 2010 Site Status, Groundwater Monitoring and Remedial Summary Report-Stockton Terminals Technical Committee Facilities conducted on January 5 and 19, February 5, and March 4, 16, 17, 23, and 31, 2010. Both systems are currently operational. In addition to the conservative estimate of hydrocarbons destroyed by chemical oxidation (presented below), ozone is unstable and that not used to oxidize hydrocarbons, very quickly breaks down into molecular oxygen. This increases DO concentrations within the radii of influence and down gradient of injection wells. The increased DO concentrations in the groundwater enhance biodegradation of petroleum hydrocarbons. A summary of each system's performance is provided below. 4.4.1 East System The East System Panel 1 had an ozone run-time of 100 percent while Panel 2 had an ozone run-time of 85 percent. The East System injected approximately 244 pounds of ozone and destroyed approximately 81 pounds of hydrocarbons during first quarter. To date the East System has injected approximately 4,354 pounds of ozone and destroyed an estimated 1,451 pounds of hydrocarbons. 4.4.2 West System The West System Panel 1 had an ozone run-time of 75 percent while Panel 2 had an ozone run-time of 74 percent. The West System injected approximately 212 pounds of ozone and destroyed an estimated 71 pounds of hydrocarbons during first quarter. Reduced run-times during first quarter were due to an unsecured panel door engaging the emergency stop (E-Stop) button. The door was secured and run-times improved. To date the West System has injected approximately 4,114 pounds of ozone and destroyed an estimated 1,371 pounds of hydrocarbons. 4.5 OZONE-INJECTION MONITORING PROGRAM A detailed description of the ozone-injection monitoring program and the Revised Contingency Plan are included in Appendix K. A summary of monitoring results and laboratory analyses for the compliance wells (listed below) are included in Table 13. Groundwater Remedial Observation Wells Mid-Point Trigger Wells Zone Observation Wells * A PS/MW-18, PS/WC-1 S, AR/MW-21A PS/MW-20A OW-2A, OW-4A B AR/MW-1813, AR/MW-21 B, PS/WC-1 M PS/MW-20B OW-213, OW-413 * PS/MW-20 has been replaced with PS/MW-20A and PS/MW-20B as discussed in Appendix K. Detections above the compliance limits (Appendix K) were not reported in any of the remedial observation wells during first quarter 2010 with the following exceptions: • AR/MW-18B — MTBE (1.5 pg/L) and TBA (44 pg/L); neither of these concentrations exceed their respective compliance limits by an order of magnitude. Additionally, these detections are reduced from their respective fourth quarter 2009 concentrations.