SITE INFORMATION AND CORRESPONDENCE

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T & T Trucking page 2 11396 Hwy 99 Frontage N, Lodi Work Pian Comment EHD cannot properly evaluate the ART technology as to being necessary and adequate for corrective action on this site. Optimal and unfavorable site conditions for ART should be identified and this site evaluated with regard to those site conditions. To date, no single technology has been demonstrated to be appropriate for all sites. Please demonstrate that the known site conditions justify the expectations for a successful application of ART technology to this site. Without this justification, EHD will not permit well installations with screened intervals greater than 20 feet and `vapor well' screens to be placed in the saturated zone. The proposal must be deemed adequate and necessary [Health & Safety Code Section 25296.10(c)(3)] prior to EHD permitting the ART technology and well design to be installed and tested. Without EHD approval, only multiple, single-casing and shorter screened interval, separate SVE and AS well casings will be permitted to be installed. EHD concurs that SVE may be effective in reducing the impact of the MtBE in the vadose zone down to ground water, but questions the design of the AS system utilizing existing MW-1. EHD is unsure how the sparged air will reach the vadose zone through the finer-grained material in the upper saturated zone and the lower unsaturated zone. The CPT logs 1 through 5 generally show an interval of high pore pressure between 65 and 70 feet bgs: this unit may provide a barrier to vertical migration of injected air. Additionally, how much dissolved oxygen is expected to escape the MW-1 well casing and get into the aquifer ground water, when it can be expected that most of the injected air will bubble straight up the well casing. Are there calculated estimates of the dissolved oxygen diffusion rate from the well casing and the time it will take to detect this in the observation well, VEW-1? Determination of an adequate test duration time is dependent upon these site-specific estimates. The Plan is not approved as submitted. Please submit an addendum that addresses the concerns noted above. You may contact Mr. Infurna if you have any questions or wish to discuss the site. You may call Mr. Infurna at (209) 468-3454 or email him at minfurna(CD-slcehd.com. Donna Heran, REHS, Director Environm ntal Health Departme Michael J. Infurna Jr., Senior REHS Nuel Henderson, P.G. LOP I Site Mitigation Unit 1V LOP/ Site Mitigation Unit IV MI/ c: CVRWQCB—J.L. Barton, Sacramento. c: SWRCB—CUF— Mark Owens, Sacramento. c: Brown & Caldwell - Tina Bauer 2701 Prospect Park Dr., Rancho Cordova.