RE TSA Annual Performance Report (1)

From: KENT Mavis D

Sent: Tue Jul 11 12:22:55 2006

To: 'Chris Kimmel'

Cc: Eric Weber; Sarah Prowell

Subject: RE: TSA Annual Performance Report

Importance: Normal

Chris, thanks for the map. Visual is best in some circumstances and it helps here to see the systems.

I had a few other questions that I will pose here, before I go forward in preparing a response letter for the annual report.

1. Under section 5.5, can you explain what you mean by the second sentence in the first paragraph? I don't understand how past decommissionings (I read here the well has been physically removed) would be re-evaluated if land use conflicts with one or more wells. What is the conflict if the wells have been removed?

2. Under section 5.5, the two bullets that define decommisioning criteria. In either one, would you propose a well for decommissioning if it remained at 5 ug/l for two years? If being at 5 ug/l is viewed as meeting the cleanup criteria then the current wording says this. If not, then should the wording indicate below 5 ug/l for two years?

3. Under Section 5.6, the last sentence in the third paragraph indicates "...replace conventional purge sampling in remedy monitorings wells except those...". Does this mean specifically the two wells with poor correlation (BOP-22(ds) and BOP-60(ds)? The section context suggests the two wells, but the sentence kind of suggests an area of the site. Just wanted to clarify.

4. Under Section 5.6, is the description of where you would place multiple diffusion bags to further evaluate vertical variation in wells 22 and 60 your proposal that you wish to have approved, or did you plan to submit a work plan?

5. Table A-1, in the notes, the definition of "P" seems to be incomplete. "Regularly scheduled water may be used for initial or final samples."? Then the last sentence talking about sampling if pumping lasts more than 3 months, does the sentence end "...until pumping stops.", or similar?

6. Table A-2, note #2 indicates that BPO-65(ds) sampling frequency is to be reduced. Would you propose to increase the frequency if an effect is noticed as a result of pumping the new well EW-23?

7. Table A-2, note #3, I have searched and can't seem to see wells PMX-166 and PMX-174. Could you give me some direction as to which of the reports' maps show these wells?

8. Table A-2, note #6. Could you give me some clarification? This note says that lower TSA water level/quality will stop (for MW-22(ds) and EMC-2(ds) which seem to be upper TSA wells) due to duplication of lower TSA well data.

9. Table A-2, note #11. Could you clarify this statement for me? It says reduce frequency for PMX-189 because of compliant concentrations one year after decommissioning. Does this mean decommissioning of the well, or something else?

Thanks for your help.

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

Sent: Tuesday, July 11, 2006 10:51 AM

To: KENT Mavis D

Cc: Eric Weber; Sarah Prowell

Subject: FW: TSA Annual Performance Report

Hello Mavis,

Attached is a site map prepared earlier this year showing the groundwater treatment systems and the individual extraction wells associated with each system. The figure provides a clear and concise summary of the groundwater system and based on your comments, we will include the figure in next years report.

I just wanted to clarify the recommendations for well decommissioning provided in the Annual Report (section 5.5). The comparison of the TCE concentrations to the MCL (5 ug/l) has been established for the project under the consent decree,the Record of Decision, and has been used historically to monitor remedy progress. For this reason, we feel it is important to remain consistent and use the 5 ug/l for comparing results and making system modifications.

*
The process for possible extraction well decommissioning will consist of identifying wells for pilot shutdown. The pilot shutdown will include discontinued pumping of the well for a 2-year period; however, during this time we will continue to collect quarterly water samples and monitor hydraulic control of the TCE plume. If concentrations routinely remain below 5 ug/L during the pilot shutdown (no detections above the MCL for 2 consecutive sampling events) and the discontinued pumping of the extraction well has not adversely effected the hydraulic control of the plume, then we will consider the pilot shutdown phase complete and collect 2 additional quarterly samples for confirmational purposes. If the confirmation samples indicate concentrations remain below the MCL, then we will propose to DEQ that the well be decommissioned. If TCE concentrations appear to fluctuate near the MCL then we can propose to extend the shutdown phase until concentrations stabilize. No decisions for decommissioning will be conducted without the full consent of DEQ.
*
Groundwater monitoring well decommissioning will be proposed to DEQ for wells that have been removed from the performance monitoring program (Table A-2) and are no longer needed to monitor groundwater quality or for monitoring hydraulic control. Wells are removed from the monitoring program if they meet the established criteria (section 5.4 of report). The criteria for well removal from the monitoring program include 1) TCE concentrations have been non-detect for 2 or more years 2) distance form the TSA plumes makes the well data unnecessary for performance evaluations 3) or the well duplicates other wells in the remedy well network. Confirmational sampling will be conducted on wells that have been removed from the monitoring program a 2 -year period. If the confirmation samples indicate concentrations remain below the MCL, then we will propose to DEQ that the well be decommissioned. Again, no decisions for decommissioning will be conducted without the full consent of DEQ.

Please let me know if we can be of further assistance during your document review.

Thank you,

Christine Kimmel, L.G.

Landau Associates

Senior Project Geologist

main (425) 778-0907

fax (425) 778-6409

cell (206) 786-3801

The information contained in this Email should be considered confidential and is intended only for the person(s) to whom it is addressed. Should you receive this transmission in error, please notify Landau Associates immediately and delete the Email.

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

Sent: Monday, July 10, 2006 4:31 PM

To: Chris Kimmel

Cc: Sarah Prowell

Subject: TSA Annual Performance Report

I am reviewing the Annual Performance Report and plan on responding by letter. One of the recommendation sections is criteria for future well decommissioning. The criteria presented for extraction and monitoring wells is no detection above 5 ug/l for two events after a 2 year shut down/non sampling period. Considering that some wells, such as MW-19(ds), increased in concentration I am wondering whether the criteria ought to be some level below 5 ug/l. Also, the stability of the area in terms of changes in pumping should be considered. I wanted to bring this up and see if you have any thoughts.