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Mr. Ken Price -2 - Supplemental 2 - Supplemental Soil/GW Sampling Report Occidental Chemical Agricultural Products,Inc. San Joaquin County and the remaining useful life of the system may not be long. Updating the system may also enhance the possibility of meeting the Tentative WDR criterion. 3.1.2 Existing Treatment System Annual and Projected Costs As stated above, the existing carbon adsorption system at the site has been in operation since mid 1982 (18 years). Table 4 depicts all of the alternative treatment technologies and modifications to the existing system having a capital cost associated with them except the Current System. What is the life of the current system? When is it anticipated that a new replacement system is needed to replace the current one? What would be the capital cost for updating the Current System? This section also discusses carbon consumption over the past five operational years(1994-1998)where the system averaged 166,000 lbs. of carbon per year. The TE Study states that, "Since the adsorption process is not linear, it was conservatively estimated that the amount of carbon consumed in an attempt to treat to the tentative WDR criteria would be increased by at least 250%." How was the 250% increase value derived? Is the 250% addition applied to a base value of 166,000 pounds? Please explain how costs were derived per pound of carbon. We believe it would be more relevant to base the estimates on carbon consumption from 1998 to the present because it would reflect the current situation with regards to influent concentrations and current carbon usage is much less than 166,000 lbs./year as explained further below. Quarterly reports for the year 2000 show that there were four pulsing periods between January through Sept.: May 23 Pulsed East Vessel (Port F) 2000 lbs. May 24 Pulsed West Vessel(Port B) 2000 lbs. July 23 Pulsed East Vessel 2000 lbs. Sept. 29 Pulsed East and West Vessel 4000 lbs. 10,000 lbs. These pulsing operations ensure that the current limits as MCLs are being achieved in compliance with existing WDRs. Assuming the system is pulsed three more times for each vessel (12,000 lbs.), carbon consumption would equal 22,000 lbs. in the year 2000. This is only 14% of the 166,000 lbs.per year estimate. A 250% increase above 12,000 lbs. to potentially meet the new lower limits equals 30,000 lbs., which is still much less than 166,000 lbs. If pulsing occurred every month at 4000 lbs./month, this would only equal 48,000 lbs./year, which is still far less than 166,000 lbs. At 4000 lbs./pulse, OCC would have to pulse the system 41.5 times to utilized 166,000 lbs./year, We believe that the carbon usage estimate grossly exaggerated the current actual carbon use. Because of the sulfolane issue, we believe that the most efficient technology to remove all contaminants would constitute an upgraded GAC system with modifications/additions and increased pulsing. We propose OCC provide the capital costs for upgrading the Current System and provide a reasonable estimate of how many pounds of carbon would be used to reach the lower limits proposed in the Tentative WDRs. WDRs can be revised to require these modifications in the form of a pilot study over a prescribed period as discussed earlier in this letter. 3.2 Modifications/Additions to the Existing System Estimated Costs Changing the flow direction should not have an impact on O&M on an annual basis. OCC has provided a one-time cost of$200,000 for testing and capital expenditures. Table 4 shows an additional $265,000 in O&M costs per year above the estimated costs to maintain the Existing System at$1,184,000 per year. Were the additional O&M costs based on an increase in cost due to a new type of carbon? How was the additional O&M cost determined? Please provide itemized details of the O&M costs supporting the $1,449,000 estimate for the Modifications/Additions to the Existing System alternative.