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3 <br /> <br />Hello Ann, <br /> <br />As we discussed, the EMI survey (attached) indicated very little change in conductivity across the <br />site. The survey data suggests the subsurface material is homogenous and consistent. I discussed <br />the results with GPRS and how they compare to the limited EMI survey performed in 2015. GPRS <br />concurs with the interpretation that the subsurface material is uniform. Mike Brown with GPRS <br />performed the 2015 EMI survey and said that in 2015 there were a lot of surface <br />impediments/obstructions: overgrown brush and weeds; fencing; miscellaneous debris, etc. He said <br />all those items contributed to the EMI filling in data gaps and making interpretations; he does not <br />have a lot of confidence in the 2015 survey performed at 17200 Murphy Parkway. At that time our <br />scope of work wasn’t to survey the Cogen property, we just tried to get what we could when GPRS <br />was at the PNA site. Either way, GPRS has confidence in the results of the EMI they performed at the <br />site last week. Whether that means there is not as much waste at the site as suspected OR the waste <br />is not consolidated enough to show changes in conductivity, I don’t know. We have to get out there <br />and perform the preliminary investigation to start answering these questions. <br /> <br />I made one change to the revised figure and boring locations that I sent you on Tuesday. I was at the <br />site yesterday and realized the conductivity change detected on the west side of the property, just <br />outside of the southwest corner of the stormwater basin, was likely from the reinforced concrete <br />surface structures located there. I moved that boring to the far northwest corner of the property where <br />you discussed wanting some investigation performed. Basically, I shifted a few boring locations and <br />added a few more for a total of 28. I added a few borings closer to the property line where the waste <br />cells are suspected to extend, and in the two areas to the far west. I removed a couple from the <br />facility footprint and one from the northern area, and then tightened up the spacing in the middle of <br />the site. The attached figure depicts the proposed boring locations. And in accordance with the work <br />plan and our discussions, we will advance step-out borings/additional borings if necessary based on <br />the information we collect during the investigation. We are not limited or constrained only to the <br />proposed borings depicted in the figure. <br /> <br />Also, we are still on schedule to begin the work at 8:00 am on 11 March 2018. <br /> <br />Please don’t hesitate to contact me with any questions or comments. <br /> <br />Thanks, <br /> <br /> <br />Brian W. Millman, P.G. <br />Senior Geologist <br />CA Professional Geologist No. 8574 <br />CA QSP/QSD No. 26882 <br />Advanced GeoEnvironmental, Inc. <br />Environmental • Compliance • Industrial Hygiene • Geotechnical <br />Phone: 800-511-9300 <br />Fax: 888-445-8786 <br />bmillman@advgeoenv.com <br />www.advgeoenv.com <br />