REVISE THIS LETTER FOR 2019 DATA AS A TEMPLATE PENDING DISCUSSION WITH DOUG WISE

July 3, 2019

Jason Hegdahl

Cascade Corporation

2201 NE 201st Avenue

Fairview, Oregon 97024

Deborah Taege

The Boeing Company

P.O. Box 2207, MIS 7A-XA

Seattle, WA 98124

RE: Annual Performance Report for 2018 and Five-Year Remedy Performance Evaluation. East Multnomah County Troutdale Sandstone Aquifer Remedy.

ECSI #1479

Dear Mr. Hegdahl and Ms. Taege,

The Oregon Department of Environmental Quality (DEQ) has reviewed the Annual Performance Report for 2018 and Five-Year Remedy Performance Evaluation. East Multnomah County Troutdale Sandstone Aquifer Remedy, dated May 31, 2019. This report was prepared on your behalf by Geosyntec Consultants, Inc., Landau Associates, Inc. and SS Papadopulos and Associates, Inc.

DEQ has the following comments:

•  In Appendix A, the abbreviation MPE is used as in “Depth Below MPE”. Please define MPE.

•  Vapor extraction well VMW-C removes far more VOCs than the other vapor wells listed in Table C-2, Appendix C. Operating parameters and well design details were not found in this report. Could other vapor wells be modified to enhance the removal of VOCs in line with the performance of VMW-C?

•  Tabulated VOC data from groundwater samples collected from monitoring wells BOP 22R(ds), BOP 60R(ds) and CMW 8(dg) are presented on the document CD. This tabulated data includes irregularities. For example, for BOP 22R (ds) on 11/4/2008, six data sets are presented. One data set includes significant detections of VOCs and the other five are uniformly below detection limits. Other groundwater sample collection dates are duplicated, as well with varied analytical results. There is no indication that these results are from split field samples. This variation calls into question the reliability of the tabulated data.

Section 7.0 Recommendations and Future Planned Activities

•  DEQ concurs with subsection 7.1, which recommends no operational changes to either the groundwater central treatment system or the soil vapor extraction system.

•  DEQ concurs with the decommissioning of monitoring wells BOP 22R(ds), BOP 60R(ds), CMW 8(dg) and CMW 10(dg) as recommended in subsection 7.2.

GSI Groundwater Solutions reviewed the document on behalf of the Portland Water Bureau and prepared a letter of findings, dated July 3, 2019. DEQ and the Portland Water Bureau concur with the GSI findings and request that the points raised be addressed in a forthcoming response.

Please feel free to call me with questions.

Sincerely,

Kenneth Thiessen RG/CEG

Northwest Region Cleanup Section

cc:

Cindy Bartlett, R.G. Geosyntec Consultants

Chris Kimmel, P.G. Landau Associates

S.S. Papadopulos

Doug Wise, Portland Water Bureau

ECSI #1479

Attachment:

July 3, 2019, GSI Water Solutions, Inc.: Review of Annual Performance Report, 1 January 2018 – 31 December 2018; Five Year Remedy Performance Evaluation; East Multnomah Troutdale Sandstone Aquifer Remedy; ECSI 1479; dated May 31, 2019.