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Mike Infurna [EH] From: Dennis Leikam [dennisl@olives.com] Sent: Thursday, June 03, 2010 3:31 PM To: Mike Infurna [EH] Subject: FW: Document sent from the Production Fax Attachments: [Untitled].pdf LJ [Untitled].pdf(139 KB) Hi Mike, Here is the schematic of how I am proposing we abandon the boreholes. We have two boreholes about 8 feet from either side of an existing monitoring well, MW-1, trying to hit the same water bearing zone as MW-1. The first hole on the east showed a saturated interval where we expected it, but it was very small (10-12 inches) . We let the hole sit overnight and no water came into the borehole. We moved to about 8 feet west of MW-1 and repeated the exercise, hit the same thing, a 8 inch saturated interval and this borehole is sitting now overnight to see if water comes in. . . .I'm assuming it will not, just like the eastern borehole. The problem is their proximity to existing MW-1 and I am hesitant to grout it and have communication with the existing well, messing up the pH. MW-1 is the subject of the nitrate investigation, and from what I understand about nitrate, it will change species with changing pH (i.e. change from nitrite to nitrate or vice versa) . What I am proposing for both wells is to use bentonite chips to seal off the sandy interval, hydrating as we go (every 2-3 feet) , then grouting to surface. Details below: East Well: Use bentonite chips for the sand interval that the "water bearing zone" is found in. The saturated interval is only about 10-12 inches in this well, but the sand interval is about 13 feet. Bentonite chips all the way up to 1 foot or so into the overlying clay layer (plus or minus 15 feet of chips) . Then grout to the ground surface. West well: Use bentonite chips for the sand interval of the "water bearing zone" . The saturated interval is only 8 inches in this location, and the sand interval is MUCH smaller than the east well, about 12 inches. If you will allow it, I'd like to use chips up to the same level as in the east well (about 15 feet of chips) , just in case the sand interval is nearby but not showing up in the core. . . .this would be the safest method of ensuring we don't impact MW-1 with grout and if you're comfortable with it (and if Frank has enough chips) , I 'd like to do this as my first choice. My second choice is to just use bentonite chips for about the bottom 5 feet, bentonite off the sand layer and up into the silt layer overlying it. Bottom line: I am proposing we use bentonite chips for both boreholes to seal the bottom 15 feet, then grout to surface (another 30 feet or so) . We would hydrate as we go, every 2-3 feet. Call me this afternoon or tomorrow to discuss, but in any case we WILL NOT DO ANYTHING until we talk to you. The plan for tomorrow is to begin drilling on the south side of the fence line, on the workplan it is MW-30 (but the MW-30 we installed is not in the target water bearing zone, it was not present) . Thanks, Dennis 1