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June 9, 2011 Mr. Michael Infuma San Joaquin County Environmental Health Department 600 East Main Street Stockton, CA 95202-3029 SUBJECT: REQUEST TO EXTEND DURATION OF PILOT TEST UST Site #3 Port of Stockton Port Road 13 at G Street Stockton, California WGR Southwest, Inc., Project No. 704.PRI.03 SJCEHD Site Code#1282124 Dear Mr. Infuma: On behalf of the Port of Stockton (The Port), WGR Southwest, Inc (WGR) has been conducting an Ozone-Peroxide Injection Pilot Test in cooperation with the San Joaquin County Environmental Health Department (EHD). This pilot test involves three injection wells which are triangularly located approximately seven feet around monitoring well MW3-3. The purpose of the pilot test was to observe how injection of these oxidants affects TPHg levels in groundwater, particularly monitoring well MW3-3. The duration of this pilot test was scheduled to last two and a half months. Currently, it is unclear from field analytical data if the initial "de-adsorption" phase has completed. We expect that another two months of monitoring will confirm consistent lower levels and thus the effectiveness of Ozone-Peroxide in treating subsurface contaminants at the site. Note that by de-adsorption, I am referring to the commonly observed occurrence when introduced chemical oxidants initially help to de-adsorb contaminants off soil particle surfaces before the actual contaminants are broken down. This causes a temporary rise in contamination levels in groundwater. After this de-adsorption phase, contamination levels lower as the oxidants continue to break down the hydrocarbons. Please refer to the attached time trend plots which show that levels in well MW3-3 may have returned to, or fallen below, baseline levels which were present before the system began operation on March 3, 2011. Please also refer to the attached figures and analytical table for more background information.