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r S). Unit Cost of Existing Carbon System From 10111107 to 217109 the pump and treat system used 22,000# Granular Activated Carbon (G.A.C.) to remove 1,025Kg(2,260#) TPHg. The cost of carbon per pound of fuel captured was $26.111#TPHg. The anticipated cost was $7.571#TPHg. This discrepancy is caused by a plume of TBA having moved in. TBA is displaced by BTEX on the G.A.C. retention sites, resulting in TBA being discharged at the same rate as BTEX is coming in. The discharge permit has zero tolerance for TBA forcing premature carbon exchanges. There have been 5 sets of filters exchanged and only the first and current set had BTEX break through. The others were exchanged because of TBA. Now that MW-10 has revealed there will be more TBA coming, the G.A.C. filters must be augmented with a bio-reactor. Foothill Engineering has designed a 2,500gal linearly progressive, submerged, fixed film, aerobic bio-reactor intended to treat the break through compounds from the carbon filters. This bio-reactor is sized to treat full strength raw water. Only a pilot test will reveal whether one bio-reactor is sufficient. G.A.C. is the only bullet proof treatment system available. The City will always require a tertiary and safety net G.A.C. filter. 6). Consideration of Alternative Systems With $25,000 fine per day per violation, any alternative must be effective on TBA, be compatible with G.A.C. and provide six months of operation for less than$75,000. Air Stripping- TBA does not air strip. With only a $75,000 revolving fund it would take two years to secure the equipment and keep up with monitoring. The UST fund will not allow accumulated rental fees to surpass the purchase price, therefore all equipment must be purchased a out right. Hydrogen Peroxide- Hydrogen Peroxide will oxidize TBA. To provide complete oxidation there must be a residual amount. The residual amount will consume the carbon in the tertiary and safety net filters. Hydrogen Peroxide is not compatible with G.A.C. and cannot be used. The estimated cost of consumables for hydrogen peroxide treatment is $121#TPHg using bulk 50% hydrogen peroxide. Bio-Reactor- Using biological activity is effective at treating TPHg and TBA. Biological activity is compatible with G.A.C. The bio-reactor can be furnished for an estimated cost of $29,000. The system is intended to eventually take over for G.A.C. and not have any consumable materials cost. Current recommendations Foothill Engineering recommends; 1). Installing a monitoring well to the North to replace the aging CPT data.