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I don't need a letter from you to continue otwnediation, but hopefully if the third and fourth quarter well sampling events show positive results, we can begin to think about moving the site to closure. Scott From: Nuel Henderson [EH] [mailto:nhenderson@sjcehd.com] Sent: Thursday, September 18, 2014 10:50 AM To: Scott Cc: cori condon@waterboards.ca.gov; Angelica Sandoval Marin [EH] Subject: RE: 1140 W. Hammer Lane, Stockton Scott, I have reviewed the analytical data for MW-11 and MW-12 and notice that the benzene in MW-12 dropped from 11,000ppb at injection startup, declined to 3,000ppb on 11/28/12, rose steadily to 4,400ppb on 8/7/13 before declining again to 3,300ppb on 3/20/14, the event just prior to the 2,100ppb in May 2014. 1 think we should see consistent concentrations below 2,000ppb for several events, not just two, or better yet one or two orders of magnitude decline of concentrations, such as is exhibited by MW-11, before turning off the system. I know it is tempting to use the LTCP criteria as cleanup goals, which may be what we effectively will do, but I think we should be running remediation systems until they decline in remedial efficiency and then evaluating the results in regard to the LTCP. So at this point, the EHD cannot approve turning off the ozone injection system until the above circumstances are met. If you need a letter to this effect, we will generate one. Regards. Nuel From: Scott [mailto:SBittinger@stratusinc.net] Sent: Wednesday, August 27, 2014 7:58 AM To: Nuel Henderson [EH]; Angelica Sandoval Marin [EH] Cc: cori.condon@waterboards.ca.gov Subject: 1140 W. Hammer Lane, Stockton Good morning all. I wanted to discuss this site with you when you have a chance.... Since September 2012, an ozone injection system has been operating at this site in Stockton. Fuel contaminant concentrations in groundwater have generally declined during the operation period. During the second quarter 2014, benzene levels in groundwater were all reported below the 3,000 ppb Low Threat Closure Policy threshold for small plumes for the first time. In the second quarter 2014 monitoring/status report issued a while back, we recommended collecting one more round of samples, while the ozone injection system remains operational, and then if concentrations of benzene in groundwater were once again below the 3,000 ppb threshold, moving the site into a phase of limited post-remediation monitoring before (hopefully) moving the site to closure. In about 4 weeks, we were planning to collect the next round of samples. When you get a chance, could you please do a quick review of the site & let me know if you are in agreement with Stratus' proposed course of action discussed above? In all honesty,we worked with Harlin Knoll on this up until system start-up, and I don't think I've e-mailed or discussed this site with anyone from San Joaquin County or the Water Board since this time (nearly 2 years). Thank you. C,-**