From: Rob B. Ede
Sent: Thu Jul 29 16:47:09 2010
To: BAYUK Dana
Cc: Bob Wyatt; Patty Dost; cstivers@anchorqea.com; John Edwards; Ben Hung; jpeale@mfainc.org; Tom McCue; coreyr@hahnenv.com; Ben Uhl
Subject: Proposed Modification to 2010 GW Mon Program-Gasco
Importance: Normal
Attachments: 2010 Gasco GW Monitoring Plan_Rev 1_07_26_2010.pdf; Hi Dana, As we discussed last week, and at your request, I have reviewed the 2010 Groundwater Monitoring Schedule for Gasco, including NW Natural monitoring activities on the Siltronic property, and have made recommendations for several modifications to be implemented in time for the 3Q event, anticipated to occur in September. As you requested, the review focused on Siltronic wells on the northern portion of that property from which data relative to potential MGP constituents are not being gathered, and where having these data may be useful for plume delineation or for monitoring concentration fluctuations over time. Based on this review, NW Natural recommends incorporating 3 Siltronic wells into the program that are not presently being monitored. These are wells WS-16-161; WS-17-52; and WS-17-94. These wells are positioned such that they may provide additional delineation / concentration trend monitoring beneath the more upland portion of the Siltronic site. In addition to the preceding, other modifications I propose at this time are the removal of Gasco DNAPL wells MW-10-25, MW-11-32, MW-16-45, and MW-18-30 from the program since we have a significant baseline data set at these locations and since DNAPL-bearing wells don't show trends and the data can be somewhat erratic depending on the inclusion of DNAPL blebs into the sample. Finally, for completeness, I have added newly installed Gasco wells MW-7-61 (replacement for abandoned well MW-13-61R) and MW-18-125 (replacement for abandoned well MW-16-125) to the program - since these wells were installed subsequent to the original submittal of the proposed program. Please let me know if you have any questions or comments concerning the proposed modifications. Regards, -Rob -- This message may contain confidential and/or privileged information. If you are not the addressee or authorized to receive this for the addressee, you must not use, copy, disclose, or take any action based upon this message or any information herein. If you receive this message in error, please advise the sender immediately by reply e-mail and delete this message. Thank you. Rob B. Ede / robe@hahnenv.com Hahn and Associates, Inc. Environmental Consultants 434 NW 6th Avenue, Suite 203 Portland, Oregon 97209-3651 Phone: 503.796.0717 / Facsimile: 503.227.2209