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Nuel Henderson [EH] From: Timothy Cuellar[tcuellar@advgeoenv.com] Sent: Tuesday, November 04, 2003 12:07 PM To: Nuel Henderson [EH] Subject: Top Filling Station Nuel, I would like to make a modification to the I.R. work plan for Top Filling, & wanted to run it through you first. Due to the significant TPH-g/BTEX numbers in ground water, the manufacturers have suggested that we will (at least initially) be going through a lot of carbon, and they have made a recommendation to me that we pretreat with air stripper prior to running hydrocarbon-impacted water through the carbon media. Based on hydrocarbon concentrations encountered last quarter, we could anticipate 50-60 pounds of carbon exhaust per day if we were to run pump-treat extracted water directly through carbon media (or approximately 130-160 days of usage before a complete change-out is necessary) ; keep in mind that each change out will cost $10, 000. So AGE anticipates spending 25-$30, 000 per year for carbon. The manufacturers have stated to me that with an air stripper, I should achieve 90% reduction in ground water concentrations (pretreatment) , which could reduce the carbon usage significantly to 5-6 pounds carbon exhaust per day, and extend the life of the carbon to approximately 1,300-1, 600 days of usage before a complete carbon change-out would be necessary (basically 3 1/2 - 4 years) . One other factor to consider is the'sensitivity of the City of Stockton permit to discharge into the sanitary sewer; I cannot have anything in the effluent. If there is any hydrocarbons detected, they shut me down and start issueing notice of violations (fines?) . Having the air stripper gives me an element of added controls, not to mention the fact the TBA is a real booger and likes to channel through some of these ground water pump-treat systems. The air stripper will significantly reduce the potential of TBA to channel through the media. An air stripper would have a 1-time cost of $5, 000; and operates off one, regenerative blower which would cost about $100.00/month in electricity. Additionally, I already have the controls for air emmisions with the cat alytic oxidizer on the site. I could simply plumb the outgoing water from the air stripper to the carbon media vessels; I could plumb the outgoing air emmissions from the air stripper and to the catalytic oxidizer. Thanks for your time and if this is acceptable, I will prepare a short letter for your approval that explains the modification to the system. - Tim 1