From: KENT Mavis D
Sent: Wed Mar 21 14:35:13 2007
To: 'Sarah Prowell'
Subject: RE: TSA EW-4 and EW-5 Pump and Conveyance Line Removal
Importance: Normal
You have accurately stated my intentions. Because you are tracking each of these stepwise decisions in ongoing remediation system modification and management, and they will show up in the annual report, I think that an email approval will be fine. I will put a copy of this email train in the file to document our "discussions" and conclusions to address EW-4 and EW-5 and the conflict of the conveyance system with the upcoming development of Cascade North property.
I would request that once the conveyance lines are removed and all other actions for EW-4 and EW-5 are complete, that you issue a brief tech memo that summarizes the rationale and actions taken for these two wells and the conveyance system, and what our decision process will be if concentrations do not continue to drop in EW-5.
Let me know how this work goes.
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: Wednesday, March 21, 2007 2:22 PM
To: KENT Mavis D
Subject: TSA EW-4 and EW-5 Pump and Conveyance Line Removal
Mavis, I think the approach you describe is good. Let me know if this correctly summarizes that approach:
EW-4 would be converted to monitoring well status, based on its compliance with the extraction well decommissioning criterion.
EW-5 would remain in “pilot shutdown” mode until it complies with the extraction well decommissioning criterion (Sept. 27, 2006 amendment to the June 30, 2006 TSA annual report), demonstrating two years of TCE concentrations consistently below the MCL . If TCE equals or exceeds the MCL for two consecutive sampling events, remedy conditions in the vicinity of EW-5 would be evaluated (likely in the annual performance report) to determine whether resumed extraction, with replacement conveyance and conduit construction, is needed.
It seems to me the primarily evaluation factor would be for maintaining hydraulic plume control. (Since, at an average extraction rate of 5 gpm, VOC mass removal would probably not be a high value rationale for resumed operation.)
Does this reflects your understanding? If so…would you like me to submit a formal request with rationale, for your reply? Or would you like to just issue such an email approval, stating these conditions? Thanks very much. – 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