From: KENT Mavis D

Sent: Mon May 04 07:54:41 2009

To: 'Chris Kimmel'; Sarah Prowell

Cc: Chaput, Kenneth G

Subject: RE: BOP-60ds sampling frequency modification

Importance: Normal

Kim, I agree with your proposed monitoring modifications and implementing them during the upcoming sampling event.

From: Chris Kimmel [mailto:CKimmel@landauinc.com]

Sent: Tuesday, April 28, 2009 1:40 PM

To: KENT Mavis D; Sarah Prowell

Cc: Chaput, Kenneth G

Subject: FW: BOP-60ds sampling frequency modification

Hello Mavis,

Due to recent elevated TCE concentrations in BOP-60(ds) and our ongoing evaluations, we propose to increase the sampling frequency from semiannual to quarterly. Through the remainder of 2009, we propose to collect quarterly samples (May, August, November) from three diffusion bags set at the same intervals as previous (159, 163, 167 ft BGS) and a conventional purge sample. Upon the completion of the 2009 data, we may recommend to return to semiannual sampling if the data supports such a recommendation.

In addition, EW-22 was permanently taken off line to reduce downward vertical gradients between the TGA and the TSA on October 29, 2008 per your approval email (October 28, 2008). The plan was to decommission the well during the 2009 construction phase of the 85-001 building expansion. However, the construction phase has been delayed until the beginning of 2010. We propose to keep EW-22 off line and convert the use to a monitoring well. The location of the well will assist with evaluating the plume movement towards EW-3. Well EW-22 has a 40 ft screen; therefore using the existing procedures for diffusion bag sampler use, we would propose to install two bags for each sampling event. The first bag will be installed towards the top of the screen (190 ft BGS) and the second will be installed towards the bottom of the screen (210 ft BGS).

If these recommendations meet your approval, we will incorporate the changes during the May 2009 sampling event.

Thank you,

Christine Kimmel, LG ¨ Senior Geologist

Landau Associates, Inc.

130 2^nd Ave. S, Edmonds, WA 98020

main 425.778.0907 ¨ direct 425.329.0254 ¨ cell 206.786.3801

ckimmel@landauinc.com ¨ www.landauinc.com

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