From: KENT Mavis D

Sent: Wed Jun 17 11:06:09 2009

To: 'Sarah Prowell'

Cc: Chris Kimmel

Subject: Semiannual Performance Report TSA Remedy

Importance: Normal

I have reviewed the Semiannual Performance Report: October 1, 2008 through March 31, 2009, dated May 28, 2009 and have the following comments.

1.  Section 2.4, second sentence, for FNTS do you mean NTS?

2.  Section 3.2, Extraction Rates. The order requires extraction at a specific level, originally to ensure full hydraulic capture of the TSA plume. The rates for extraction are on Table A-1. The text indicates that the currently measured rates reflect a decline (in pumping rate?) relative to prior months. The text should be more specific that the total plume volume is declining and therefore the total pumping rate needed to maintain hydraulic control is declining. As a suggestion to consider, if it would not be onerous, is some kind of diagram showing the decline in plume volume along with the decline in pumping rate, particularly if a threshold indicator can be used to show that the declining rate is consistent with hydraulic control. We could discuss this idea to see if it would add any value to the reports for future report readers.

3.  Section 5.0 first bullet. It wasn’t clear whether the water level declines affected only the western portion of the plume area, or whether the affect (smaller or larger) extended to the entire plume area. Perhaps a statement could be made in this bullet as to what portion of the plume area-wise is affected during City pumping.

4.  Table A-1. I may have missed it but don’t see units on this table.

5.  Recommendations:

·  Section 6.1, continue previously approved extraction well operations: DEQ agrees

·  Section 6.3 first bullet, convert well EW-8 to monitoring well after August sampling: DEQ agrees, but the text should indicate providing that concentrations in EW-8 in August are below 5 ug/l for TCE.

·  Section 6.3, second bullet, CTS effluent sampling change from monthly to quarterly: DEQ agrees, also typo in third line “…decrease in dissolved plume…”

·  Section 6.3, third bullet, sampling frequency for BOP-70(ds-215) and BOP-71(ds) change from quarterly to semiannual: DEQ agrees

·  Section 6.3, fourth bullet, increase water level frequency for wells BOP-13(ds), BOP-31(ds) and D-17(ds) from semiannual to annual: DEQ agrees

·  Section 6.4, apply previous contingency PWB response monitoring for BOP-22(ds) to new replacement well BOP-22R(ds): DEQ agrees

·  Section 6.5, diffusion bag sampling at 159, 163, and 167 ft in BOP-60(ds) continues quarterly through 2009, along with purge samples, during BOP-60(ds) evaluation: DEQ agrees

Let me know if you would like to discuss these comments. Pages with text changes could be inserted into the bound copy of the semiannual report that you have already submitted.