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• • Page 2 of 3 To: Nuel Henderson [EH] Cc: Project Email Filing Subject: Cordes Ranch Well Destructions —COR-060223-2014— Hi COR-060223-2014Hi Newel- Thanks for taking my call regarding the well demos at the Cordes Ranch project in Tracy CA. Here is the info (attached)that I said I would send to you: • 24550 Hansen Road 2.pdf—these are the well demo permits issued by SJCEHD(Johnny Yoakum). • SJCEHD Well Demo Permit Approval.pdf—email string that transmits issuance of well demo permits from Johnny Yoakum. • RWQCB Well Demo WP Approval.pdf—email approval of well demo work plan from Michael Smith,the RWQCB case worker. • 060223-WELL DATA.xIs—this is the historical well info. o First worksheet has groundwater monitoring data. I highlighted wells that we considered "clean"green and impacted wells red (MW-2, MW-5A, and MW-15). o Second worksheet lists the well construction details(diameter, depth,screened interval). You indicated in our conversation that you approve pressure grouting of 10 wells: MW-3, MW-6, MW-7, MW-8, MW-9, MW-10, MW-11, MW-12, MW-14b,and MW-14c(total 10 wells). This would leave over- drilling of MW-1, MW-2, MW-4, MW-5a, MW-5b, MW-5c, MW-13b, MW-13c, and MW-15(total9 wells). I am not sure why wells MW-1 and MW-4 did not make your pressure-grout list. MW-1 has been consistently non-detect. MW-4 has one low concentration,j-flagged detection (330 ug/L)that was a split sample that didn't meet lab QA/QC limits. The corresponding split was non-detect. I talked to my field guy and the following wells have already been pressure-grouted: MW-6, MW-8, MW-9, MW-10, and MW-11. So at this point, we have only pressure-grouted wells that are on your approved list above. I respectfully request you reconsider our proposal for wells to be pressure-grouted based on the following information paraphrased from our May 13, 2013 Site Conceptual Model. g/L.ETPHc detections in Zones B and C are infrequent and random, ranging from non-detect to 2,800 Furthermore, the random detections of TPHc are relatively low concentration and are typically flagged by the laboratory as "hydrocarbon result partly due to individual peak(s)in quantitation range." Particularly random are the TPHc detections at well MW-148, which is located over 320 feet laterally(northwest)from the pipeline, and cross-gradient to the groundwaterflow direction. Again, TPHc concentrations at this depth (125 ft bgs)and lateral distance(320 feet)from the pipeline is not consistent with the behavior of weathered crude oil particularly in the low permeability soils encountered at the Site. Below is the Geotracker link to this Site Conceptual Model for your reference. Refer to Section 5.2.2.2 (page 22)and Section 5.2.2.3 (page 23). It is explained that we did some forensic analysis and determined that the deeper(B and C zone) detections appeared to be naturally-occurring hydrocarbons, not crude from the former pipeline,which the RWQCB has verbally agreed with in an April 23, 2014 meeting. Furthermore,wells MW-5b and MW-Sc have an 8"diameter steel conductor casing which provides an added level to protection/seal. http://geotracker.waterboards.ca.gov/esi/uploads/eeo report/9141163647/SL0607708243.PDF 7/18/2014