From: KENT Mavis D

Sent: Mon May 21 16:32:53 2007

To: 'Sarah Prowell'

Subject: RE: Gresham Development - EW-9 and BOP-4(usg) Issues

Importance: Normal

For EW-9, it looks as though it does meet the criteria to convert to a monitoring well so I would agree to convert it. The only difficulty in not replacing the piping now is whether it will be possible later to install piping after the City has finished their development. I would rather look at not reinstalling the piping on the likely outcome that the well will continue to be compliant and no extraction would be needed, than to reinstall now only to find out that the piping is not necessary. Doing that takes a risk of not being able to reinstall later if needed but you may already know whether there will be more permanent structures where the conveyance lines would need to go.

For MW-44(usg), we would need to keep this well. Are there any options for other wells to use in its place? Will the City accept the well head raising and deck for sampling, or is that the issue in the middle of their project?

Mavis D. Kent

Cleanup & Emergency Response Section

DEQ Northwest Region - East Side Office

1550 NW Eastman Parkway, Suite 290

Gresham, Oregon 97030

503-667-8414 X55008

503-674-5148 Fax

kent.mavis.d@deq.state.or.us

-----Original Message-----

From: Sarah Prowell [mailto:sprowell@ix.netcom.com]

Sent: Monday, May 21, 2007 4:11 PM

To: KENT Mavis D

Subject: Gresham Development - EW-9 and BOP-4(usg) Issues

Mavis,

The City of Gresham’s consultants (Brown and Caldwell), have asked for feedback on two TSA remedy issues, for use in finalizing their Storm water Improvement construction plans for this summer. So I wanted to give you a heads up as to the requests and provide some preliminary background info, for your consideration.

1. 1. They note that the conveyance and electrical lines that extend from the NTS to EW-9 are at a higher elevation than the final grade designed for their site. The line will need to be removed to accommodate their grading and final site construction, and if required, reinstalled at a lower grade to maintain the potential for resumed extraction of pilot shutdown well EW-9. –So I wanted to confirm your thoughts on whether the EW-9 line reinstallation is need or whether this well might be approved for conversion to monitoring well status?

   This is an Upper TSA well and has contained TCE at concentrations consistently below the MCL since February 2003, at about which time Upper TSA extraction well EW-22 began to operate to capture TCE in the Upper TSA near BOP-22(ds). (EW-22 now operates about 250 gpm, while EW-9 has been in pilot shutdown mode since June 2006.)

2. 2. The City of Gresham also asks whether SGA monitoring well MW-44(usg) may be decommissioned, because it is located inside the holding pond area planned for seasonal storm water collection. I understand there will be about 2 to 3 feet of standing water around the area of BOP-44(usg) during the winter season. The well head is currently planned to be extended vertically so it will stand about 3 feet above the seasonal water level, with a deck constructed to allow monitoring access throughout the year. –The SGA is fully restored, however, this well is part of a core set of SGA wells [mainly, BOP-68(usg), BOP-44(usg), and PWB-1(usg)], that we anticipated using for several more years to verify PWB well field protection during its pumping events. However, the Lower TSA is also compliant in this area (EW-19 TCE concentrations have remained consistently below the MCL during the last year).

Let me know if you would like to discuss these issues or receive more information to better evaluate them.

Thanks once again for your help. –Sarah

Sarah Prowell, R.G.

Prowell Environmental, Inc.

2216 SW Sunset Blvd.

Portland, OR 97239

Phone: 503/452-0972

Fax: 503/452-1427

Email: sprowell@ix.netcom.com