SITE INFORMATION AND CORRESPONDENCE

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Cleanup technologies proposed for Stockton Avenue cleanup are as follows: 1.) Vacuum Extraction/Carbon Absorption 2.) Ultraviolet light/Hydrogen Peroxide Oxidation 3.) In-Situ Bioremediation Each of these technologies will be described separately, however, the optimum treatment program will probably employ a combination of cleanup processes. 1.) Vacuum Extraction/Carbon Absorption would be installed as schematically shown on Drawing #3. The vacuum pump is a water ring seal vacuum pump with a 40 horsepower motor. The vacuum pump will pull enough vacuum on the well (20-25" Hg vacuum) to pull contaminated gas and water from the soil down to the water table. The gas and water are separated in a cyclone separator. Gas travels through carbon canisters or totes set up for gas flow. Water is pumped from the cyclone separator through carbon canisters or totes set up for liquid flow. The gas and water flows are regularly sampled to monitor the contamination levels by injecting samples into gas chromatograph, we can get ppm readings for gas stream and ppb readings for water stream. The inlet sample to carbon tells us how contami- nated the well is and how fast we are cleaning it up. The outlet sample from the drums tells us that the carbon is removing the contaminant from the air or water that is being discharged from the cleanup process. Whenever the readings out of the carbon drums begin to rise, we change out spent contaminated carbon for new virgin carbon. The spent carbon is transported by registered and permitted hazardous waste hauler to a facility that is registered and permitted to regenerate the spent carbon in a furnace. When vacuum extraction is first started it will be monitored closely to establish the relationship between contamination and carbon loading. By observing the concentration of contaminant to the carbon and the length of time until breakthrough when we detect contaminant coming through carbon, we can accurately predict when to shutdown and change carbon. Figure #1 shows a typical drop in the soil gas contaminant levels over approximately two months of vacuum extraction. We would propose to run soil vacuuming 24 hours per day for as long as we were still getting contaminants out of the ground. The equipment should not be any noisier than a city well pump. We can add noise panels, if needed. We think this process will be a key player in removing the high levels of contamination in the shallow zone (B Zone and above) .