From: KENT Mavis D

Sent: Tue Nov 03 14:38:57 2009

To: 'Sarah Prowell'

Cc: 'Chris Kimmel '

Subject: RE: TSA Wells EW-11, EW-18, and MW-14Rds - Proposed Changes

Importance: Normal

Thanks for the further explanation on the location of diffusion bags versus pump, and also the concept of pilot shutdown when a well is no longer needed for its purpose and that work is done adequately by a nearby well(s). I can agree to both pilot shutdown of well EW-18 and EW-11 on this basis. Also, while assuming that you take the diffusion bag samples before you do a purge sample, I would agree with you that you are likely drawing higher concentration groundwater back into well EW-11 when you sample it. It seems like the overriding issue is that when the plume recedes, it is counterproductive to pump on the fringes and continue to keep a gradient to the unneeded well. The same would be true for sampling.

Let me know if you have any other questions on this.

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

Sent: Tuesday, November 03, 2009 2:03 PM

To: KENT Mavis D

Cc: 'Chris Kimmel '

Subject: RE: TSA Wells EW-11, EW-18, and MW-14Rds - Proposed Changes

Mavis,

Thank you for the approval to pilot shutdown EW-18. It’s much appreciated.

Regarding EW-11, we seek DEQ’s approval for permanent conversion to monitoring well status, as this well is no longer needed for plume capture or remediation. Just as previously implemented for EW-8 and EW-12, the conversion of EW-11 to permanent monitoring well status is requested because plume capture is already being achieved by another nearby operating TSA extraction well (EW-15) and EW-11 is no longer needed.

The recent permanent conversion to monitoring status for EW-8 and EW-12 was not based on consistent compliance with the MCL for 2 years, but rather, because these wells were no longer needed for remediation pumping due to another nearby well (EW-23) which achieves capture and plume extraction/treatment and because their operation countered plume shrinkage goals. TCE concentrations in EW-8 and EW-12 had recently achieved low levels near the MCL, similar to EW-11, but not consistent compliance for 2 years. For this category of pilot shutdown and conversion, the decisions have been made because another operating well achieves plume capture and cleanup goals, without ongoing use of the duplicative EW-8, EW-12, or EW-11 wells.

Therefore we seek DEQ’s approval for EW-11 permanent conversion to monitoring well status.

Regarding EW-11 water quality sampling, the diffusion bags are set above the pump. The center of the upper bag is set below the top of well screen a distance = 1/3 the total screen length (i.e., 40 ft screen length / 3 = 13.3 ft). The center of the Lower diff bag is set approximately 13.3 ft above the bottom of well screen. The pump is set about 8 feet above the bottom of screen, therefore not too far below the Lower diff bag.

The key points, I believe, are:

· both the EW-11 Upper and Lower passive diff bags show comparable concentrations (2.7 and 2.4 ug/L), and reflect near well water quality conditions

· the EW-11 purge sample concentration was higher (5.9 ug/L) than for diff bags, and matches the TCE concentration in EW-15 (5.9 ug/L).

The data are consistent with the conclusion that EW-11 purge pumping (with a much larger purge volume than for monitoring wells) likely pulls groundwater toward EW-11 from the EW-15 plume vicinity, temporarily spreading the plume eastward toward EW-11. This is reinforced by the presence of lower TCE concentrations in EW-11 diff bag samples, which characterize water quality in the near well vicinity.

Because the performance monitoring goal is to monitor water quality conditions in the well vicinity, diffusion bag sampling is recommended.

Thanks very much. Sarah

From: KENT Mavis D [mailto:KENT.Mavis@deq.state.or.us]

Sent: Monday, November 02, 2009 4:32 PM

To: Sarah Prowell

Cc: Chris Kimmel

Subject: RE: TSA Wells EW-11, EW-18, and MW-14Rds - Proposed Changes

The email from Chris to you on October 5 indicated a preference to continue taking purge samples along with diffusion bag samples because of the variation. Below you indicate you are in agreement to stop taking purge samples and only take diffusion samples. I was sort of leaning toward continuing both at least for another round (only two with both at this time). However, I wondered if you could tell me what the elevation is of the pump for purge sampling compared to the diffusion bag sample elevations. My thought is that if they are equivalent elevations, or if the diffusion bags samples overlap or bracket the pump elevation, then I could agree to go only diffusion bag samples.

I also need to go back to the criteria in the annual report to refresh my memory if compliant concentrations for one year is within the decision criteria for pilot shutdown. Well EW-18 pilot shut down looks good and with the ability to resume extraction if two quarterly samples are above the MCL it would be “no harm-no foul”.

Let me know. I will be in all day tomorrow.

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

Sent: Monday, October 26, 2009 11:00 AM

To: KENT Mavis D

Cc: Chris Kimmel

Subject: FW: TSA Wells EW-11, EW-18, and MW-14Rds - Proposed Changes

Hello Mavis,

FYI, Chris Kimmel and I agree that diffusion bag sampling would be sufficient for EW-11, since purge sampling appears to be pulling the EW-15 plume area toward EW-11. I wonder if DEQ approves the EW-11 and EW-18 recommendations below?

Thanks. Sarah

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

Sent: Tuesday, October 13, 2009 12:26 PM

To: Mavis Kent (KENT.Mavis.D@deq.state.or.us)

Cc: Chris Kimmel

Subject: FW: TSA Wells EW-11, EW-18, and MW-14Rds - Proposed Changes

Dear Mavis,

Please find attached VOC data (through Sept 2009) for TSA pilot shutdown well EW-11 and for pulse pump well EW-18, with its associated pulse pump monitor well MW-14Rds. Chris Kimmel and I have reviewed the data, and per the discussion below, would like to request DEQ’s approval to (1) permanently convert EW-11 to monitoring well status (with ongoing operation of nearby extraction well EW-15) and (2) to convert EW-18 to pilot shutdown status.

(Note: Also attached for your well location reference, is the previously issued Lower TSA TCE contour figure, showing August 2008 through March 2009 data. FYI, the current, August 2009 joint contour figure is not yet complete.)

Re: EW-11 -

• * EW-11 was pilot shutdown in Dec. 2007 because of low TCE concentrations and ongoing operation of and plume capture by extraction well EW-15.
• * Following EW-11 pilot shutdown, TCE in EW-11 purge samples temporarily increased to 7.4 mg/L in Nov. 2008 and then declined to 5.9 mg/L by August 2009.
• * Both purge and diffusion bag samples were collected in EW-11 in May 2009 and Sept 2009. The diffusion bag samples contained lower TCE concentrations than for purge samples. The most recent data (Sept. 2009) show TCE concentrations of 2.7 and 2.4 mg/L in the Upper and Lower EW-11 diffusion bag samples.

The data indicate TCE concentrations in the near vicinity of EW-11 (i.e., passive diffusion bag samples) are lower than TCE concentrations in adjacent areas (per purge samples, with actively induced flow toward EW-11). And it seems likely that TCE is temporarily spreading from areas near EW-11 (from areas between EW-11 and EW-15) toward EW-11 during EW-11 purge sampling. (FYI, TCE was detected in the EX-15 August 2009 purge samples at 5.7 and 5.9 mg/L,…compared with 5.9 mg/L in the EW-11 August 2009 purge sample.)

• * Given the compliant EW-11 diffusion bag TCE data, and the original shutdown condition that EW-11 pumping is not needed, given EW-15 operation and plume capture, we propose that EW-11 be permanently converted to monitoring use, with associated final pump removal.
• * Regarding future EW-11 sampling, could you advise us as to whether DEQ would like to see (1) both diffusion bag (Upper and Lower) and purge samples, given the variability in TCE sample data (in which case we would keep the pump in the well), (2) or use Upper and Lower diffusion bags only, evaluating near-well conditions?

Re: EW-18 and MW-14Rds –

• * Pulse pump operation began Jan. 2008 and TCE concentrations since that time have remained low, declining to levels consistently below the MCL during 2009.
• * TCE in MW-14Rds declined notably following EW-18 pulse pump operation and has declined further since that time to levels consistently below the MCL during 2009.

• * Based on the absence of concentration rebound during on-off pulse pump operation, and the stable, compliant TCE concentrations during 2009, we propose to pilot shutdown EW-18. Consistent with the TSA extraction well pilot shutdown criteria: If TCE concentrations increase to levels equal to or above the MCL for two consecutive quarters, EW-18 extraction shall resume. If TCE remains consistently below the MCL for 2 consecutive years, decommissioning or permanent conversion to monitoring well status may be proposed to DEQ.

We seek DEQ’s comments or approval of the above recommendations.

Sincerely, Sarah

Sarah Prowell, R.G.

Prowell Environmental, Inc.

2216 SW Sunset Blvd.

Portland, Oregon 97239

Phone: 503/452-0972

Fax: 503/452-1427

sprowell@ix.netcom.com

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

Sent: Monday, October 05, 2009 2:44 PM

To: Sarah Prowell

Subject: RE: TSA Wells EW-11, EW-18, and MW-14Rds - Proposed Changes

Hello Sarah,

I am in support of the conversion of EW-18 to pilot shutdown status based on the below MCL concentrations for at least one year at both EW-18 and MW-14. I also support the conversion of EW-11 from extraction pilot shutdown status to monitoring well use, in the condition that EW-15 remains operational and that TCE concentrations remain below the MCL for the diffusion bag samples. I would recommend the continued sample collection of purge samples at EW-11 given the variation in the results compared to diffusion samples.

Thank you, as you indicated below, please provide recommendation to DEQ and cc me.

Christine Kimmel, L.G.

Senior Geologist

Landau Associates Inc.

130 2nd Ave South

Edmonds, WA 98020

(425) 778-0907

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

Sent: Friday, October 02, 2009 11:19 AM

To: Chris Kimmel

Subject: TSA Wells EW-11, EW-18, and MW-14Rds - Proposed Changes

Hello Chris,

I’m forwarding VOC data (through Sept ’09) for TSA pilot shutdown well EW-11, as well as for pulse pump well EW-18 and its associated pulse pump monitor well MW-14Rds. I’d like to explore with you, thoughts on EW-11 conversion to monitoring well status and EW-18 conversion to pilot shutdown status.

Re: EW-11 -

• * This well was pilot shutdown Dec. ’07 because of low TCE concentrations and ongoing plume capture by EW-15.
• * Following pilot shutdown, TCE in EW-11 purge samples temporarily increased to 7.4 mg/L in Nov. ’08 and then declined to 5.9 mg/L by August ’09.
• * EW-11 diffusion bag samples in May ’09 and Sept ’09 contained lower TCE concentrations than did purge samples, with Sept. ’09 TCE concentrations of 2.7 and 2.4 mg/L (in Upper and Lower diff bags).

The data indicate TCE concentrations in the near vicinity of EW-11 (i.e., passive diffusion bag samples) are lower than TCE concentrations in adjacent areas (per purge samples, with actively induced flow toward EW-11). And it seems likely that TCE is temporarily spreading from areas near EW-11 (between EW-11 and EW-15) toward EW-11 during EW-11 purge sampling.

Given the compliant EW-11 diffusion bag TCE data, and the original shutdown premise that EW-11 pumping is not needed, given EW-15 operation, I’d like to propose EW-11 be permanently converted to monitoring use, with associated final pump removal.

And re: EW-18 and MW-14Rds –

• * Pulse pump operation began Jan. ’08, and TCE concentrations since that time have remained low, declining to levels consistently below the MCL during ’09.
• * TCE in MW-14Rds declined notably following EW-18 pulse pump operation and has declined further since that time to levels consistently below the MCL during ’09.

The data show an absence of concentration rebound during pulse pumping,…so I would like to propose pilot shutdown of EW-18 to evaluate whether TCE concentrations remain stable.

Could you let me know if you have comments or agree with the proposed changes? If we agree, I’d like to email DEQ, ccing you, with a request for the changes. Let me know your thoughts.

Thanks. Sarah

Sarah Prowell, R.G.

Prowell Environmental, Inc.

2216 SW Sunset Blvd.

Portland, Oregon 97239

Phone: 503/452-0972

Fax: 503/452-1427

sprowell@ix.netcom.com