March 12, 2020

Cindy Bartlett, R.G.

Geosyntec Consultants

920 SW Suite 600

Portland, Oregon 97204

RE:  Data Gaps Investigation Work Plan

East Multnomah County Troutdale Sandstone Aquifer Remedy (ECSI 1479)

Geosyntec Project Number: PNG0564S19

Dear Ms. Bartlett,

The Oregon Department of Environmental Quality (DEQ) has reviewed the document entitled Data Gaps Investigation Work Plan East Multnomah County Troutdale Sandstone Aquifer Remedy, dated February 21, 2020. DEQ approves the Work Plan as presented.

As well, thank you Cindy for your explanatory phone call with me earlier this week. Please keep DEQ informed on the implementation schedule for the proposed work.

Please feel free to call me with questions.

Sincerely,

Kenneth Thiessen, CEG

Northwest Region Cleanup Section

cc:  Brent Miller, P.E. Geosyntec Consultants

Chris Kimmel, Landau Associates

Jason Hegdahl, Cascade Corporation

Debbie Taege, The Boeing Company

ECSI #1479