SITE INFORMATION AND CORRESPONDENCE (2)

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. a i • Page 1 of 2 Mike Infurna [EH] From: Matt Hanko[hanko@geoconinc.com] Sent: Wednesday, December 03, 2003 5:32 PM To: Mike Infurna [EH] Subject: Ranch Market Mike: RE: Ranch Market, 23569 South Santa Fe Road, Riverbank, CA I have attached two documents to assist you in following the discussion presented below. Attachment, Table 3 from 3Q-03 presents SVE performance data from when we surged the system and the O&M Tables depict the most current data for the SVE system performance. An SVE system and ozone sparge system are currently operated at the site. The SVE skid consists of a 300 scfm blower and knockout pot and uses GAC as the abatement media. The former SVE system consisted of a 500 scfm blower and used CAT/OX as the abatement media. As depicted in the attached Table 3 from 3Q-03, in April 2003 the SVE performance was poor with low vacuum and flow rates and low contaminant concentrations. We shut down the system in May for 18 days. The data in Table 3 Surge Performance demonstrates that contaminant concentrations did not rebound and supported the use of Granular Activated Carbon (GAG) as the abatement method. The surge performance and system switch were all discussed in our Second/Third Quarter report dated July 2003. The switch from CAT/OX to GAC was made in June 2003. Upon startup of the 300 scfm with GAC system in June 2003, greater vacuum and higher flow rates were achieved (refer to Table 3 of the O&M Tables)than those attained from the previous SVE system. As a result of the increased vacuum significantly higher contaminant influent concentrations were achieved. The contaminant concentrations in vapor well V-3 increased most notably than any other well (refer to Table 6 of the O&M tables)and the flow rate also increased most significantly. In fact, vapor well V-3 was the only well that exhibited a reversal in the decreasing contaminant trend (based on PID field readings- refer to Table 6 of the O&M Tables). No analytical data exists for individual vapor wells. The approximate O&M costs for the 500 scfm blower with CAT/OX was$5,600 per month. Currently the GAC is requiring change out every month at a cost of$6,100. The total O&M costs for the 300 scfm GAG system is approximately$8,300 per month. Geocon is proposing to mobilize a 300 scfm CAT/OX unit to the site to replace the 300 scfm GAC unit. The expected duration of operation for 300 scfm CAT/OX unit is unknown. However, Geocon proposes to extract from vapor wells V-3, V-5, and V-6 only for two months with the 300 scfm CAT/OX unit. The objective would be to reduce the mass load within the influence of those wells quickly and reduce concentrations so that GAC can be used economically at the site. If the influent concentrations have not been reduced to target levels(noted below), the 300 scfm CAT/OX system will remain in use until target levels are achieved. In order to make the switch, the SJUAPCD will require that a new Authority to Construct Application be submitted and processed (14 days to process). The units will switch out easily, in that, each is mounted on a trailer and can be rolled in and rolled out. Our total cost to make the switch will be under$1,000. O&M Cost Comparison between systems: Former 500 scfm CAT/OX(natural gas fired) _$5,600 per month Current 300 scfm GAG (with 4,000 Ib GAC change every 1 month) _ $8,300 300 scfm CAT/OX(electrically fired) $4,900 300 scfm GAG (with 4,000 Ib GAC change out every 2 months) =4,650 300 scfm GAG (with 4,000 Ib GAC change out every 3 months) _$3,950 12/8/2003