SITE INFORMATION AND CORRESPONDENCE

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Mr. Ray Baglietto and Mr. Frank Razui -2 - 18 July 2005 • 5-6-2005: "Conducted acid wash on unit C2." • 5-10-2005: "Conducted acid wash on unit CI and restarted system. "(Note that water samples from the GWP&TS were not analyzed prior to resuming the discharge.) • 5-23-2005: "Sampled treatment system; breakthrough detected in lead unit c2 (2.1 ppb MTBE) and unit Cl (52 ppb). Preliminary results were provided to Ground Zero late on May 31, 2005." • 5-31-2005: `After preliminary results from May 23, 2005 sampling indicated carbon breakthrough, Ground Zero immediately resampled CI and C2 to confirm breakthrough and shut down the treatment system. Ground Zero notified Jim Barton of the Regional Board via voicemail on the morning of June 1, 2005 and followed up with an email to Mr. Barton and Mr. Jeff Wong of San Joaquin County EHD on the morning of June 2, 2005. Confirmation samples indicated(Lead) C2 contained 2.4 ppb MTBE and CI contained 29 ppb MTBE. Between May 10 and May 31, approximately 43,079 gallons of extracted water were treated. Based upon the May 23, 2005 analytical results, approximately 1.5 pounds of TPHg, 0.8 pounds of BTEX, and 1.6 pounds of MTBE were removed from groundwater during that period." The Report states in the Analysis of the Breakthrough section that: • There was ample capacity remaining in the GAC for petroleum hydrocarbons removed after the acid washes. • There was no indication that the acid wash would release petroleum hydrocarbons, or"...,affect the absorption capacity of the GAC." The pH was 6.7 after acid washing,down from the normal 7.0 to 8.2 pH. The Report does not name a single cause for the Breakthrough, but states that: • Afterwards,the GAC material supplier(Carbon Resources)concluded that acid washing with back flushing "...could have affected the equilibrium zone (zone of exhaustion) in the carbon units, thereby reducing the effective life of the carbon units... ". • "The replacement carbon delivered by Carbon Resources in December 2004 was a different product than what was delivered in December 2003. A coconut-based product...used in December 2003, is preferred for treating MTBE. The carbon delivered in December 2004 was...a coal-based carbon. " • "Decreasing efficiency of the air stripper may have contributed to somewhat increased load to the carbon units... ". The Report concludes that: • Breakthrough initially 6ecurred between 11 May and 23 May 2005. • Between 0.004 and 0.02 pounds of MTBE were discharged to land mixed with water from the malfunctioning treatment system. • Ponding of water in the discharge area(noted by San Joaquin County Mosquito Vector Control)due to construction grading activities for the Hammer Lane freeway exit project may have reduced the loading to the soil due to evaporation. The Report recommends the following to re-establish compliance with the General Order, prior to restarting the GWP&TS: • "Exchange the GAC currently in the carbon vessels with virgin, coconut-based GAC ... " • "Pressure wash removable trays in the air stripper to remove scale to increase efficiency... " • "Request modifications to WDRs, if necessary, to incorporate pre-treatment of the influent water with a phosphate sequestrant to inhibit scaling. Ground Zero has been working with the Regional Board since April in an effort to resolve this issue. • Request modifications to WDRs, if necessary, to discharge treated water over a larger area to eliminate Handing in the discharge area. "