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Portland Gas Manufacturing Site

Summary Information
(last updated on: 12/24/2020 10:30:45 AM)
A comprehensive source control investigation effort has been completed at the site under a Consent Order with DEQ. Work has included installation and monitoring of numerous upland wells to determine the potential for contaminated groundwater to discharge to the Willamette River, and a comprehensive investigation of river sediment and water adjacent to the site.

Near the seawall (eastern upland boundry), groundwater impacts have been observed in upland wells, notably in the 65-75' bgs, with MGP constituents including benzene and naphthalene observed. Groundwater above and below has minimal or no contamination. In the river, significant sediment contamination has been detected off of Block 4 and 5, and to a lesser extent Block 21. Contaminants detected included VOCs, PAHs, metals, and cyanide (all MGP waste constituents). Block 5 was the locus of MGP operations at the former PGM facility.

Summary of Investigative Work:

In October 2012, additional source control work was completed at DEQ's request. Work included sediment sampling to define the lateral extent of sediment impacts, pore and river water sampling, seismic profiling of the riverbed, and a diver survey of riverbed debris and a tar area. Upland work included a transducer study using site wells. Results were presented in a site investigation report presented to DEQ.

A Draft Integrated Sediment Investigation/Source Control Evaluation Report, including a comprehensive risk screening for both upland and in-water contamination, was completed by Anchor for NW Natural in April 2013. Based on comments by DEQ, a Revised Integrated Sediment Investigation/Source Control Evalution Report was submitted in Aug. 2013. Risk screening identified elevated concentrations of MGP contaminants in both upland groundwater (largely in the 65-75' bgs zone), and Willamette River sediment adjacent to the site.

To finalize the RI and risk screening work and prepare for a site feasibility study, a Supplement to the Integrated Sediment Investigation/Source Control Evaluation (Nov. 2013) was submitted by NW Natural. A revised Supplement was approved by DEQ in Feb. 2014.

Two FS-related documents, a FS Work Plan and Annotated FS Outline were submitted by NW Natural in early 2014. The work plan outlined additional in-water investigation work including porewater and seepage rate measurements, and advancing cores to better delineate sediment impacts in the northeast portion of in-water contamination. This work was approved in June 2014 and implemented that summer.

An Integrated Feasibility Study report was submitted for DEQ review in December 2015. DEQ issued comments on the FS dated February 11, 2016. Under the draft FS, the proposed remedy consisted of a combination of active (dredging, capping) and passive (natural attenuation) elements. The FS was finalized (Aug. 2016) and subsequently approved by DEQ. A DEQ Staff Report outlining the proposed site remedy was prepared (Oct. 2016) and approved by DEQ management.

Record of Decision issued by DEQ July 3, 2017. Included response to EPA, tribal, and public comments and evaluation of remedy consistency with that for Portland Harbor. A Pre-Design Work Plan was completed by NWN in August 2017 and approved by DEQ. Work including an updated bathymetric survey, diver survey, and sediment collection and was completed in September/October 2017.

Remedial Design and Remedial Action:

A final (100%) remedial design document was submitted to DEQ in May 2019, and comments prepared by DEQ. Final revision of the document is expected in June, after which it will be approved. Plans call for development of the separate long-term monitoring plan before the end of 2019. Remedy implementation, delayed by permitting issues, is planned for 2020. On March 2, 2020, the final design report (v4) was approved by DEQ. The Contractor Work Plan was approved by DEQ on March 27, 2020. In-water cleanup actions began on July 10, 2020 and were completed on October 14, 2020. Approximately 4,700 cubic yards of contaminated sediment were removed and clean cap material was placed over approximately 1.5 acres.

Contamination in the 5-block upland portion of the site is not included in the proposed remedy. Given filling and redevelopment that has occurred, the "direct contact" risk is considered low, and will likely be evaluated in the future. DEQ previously issued a conditional NFA for Block 15, which lies within the historical "footprint" of PGM upland activities.

General Site Information
Site: Portland Gas Manufacturing Site (ECSI Site ID: 1138) CERCLIS (EPA) Id981762818
Project Manager: Sarah Greenfield Investigative Status:Contamination Suspected
PM Phone: (503)229-5245 NPL(National Priority Listing):No
Address: Bounded by NW Everett/Glisan/2nd/Willamette River Is this site an Orphan?No
Portland, 97209 Is this site a brownfield?No
County: MULTNOMAH Action Underway or Needed: OPERATION & MAINTENANCE
Region: Northwest Region Click for more details ...  
Site Documents
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File NameCategory File Size MB Document Date Upload Date
Draft Feasibility Study - DEQ Comments February 2016.pdf Correspondence 0.1241 2/5/2016 2/7/2016
Portland Gas Manufacturing Plant fact sheet, 2009.pdf Fact Sheets 0.3111 10/18/2011
Factsheet June 2014.pdf Fact Sheets 0.3221 6/3/2014
PGM Factsheet August 2016.pdf Fact Sheets 0.3020 7/26/2016 7/26/2016
Cleanup Factsheet June 25 2020.pdf Fact Sheets 0.4710 6/25/2020 6/25/2020
Fmr Portland Gas Mftg - Consent Order.pdf Miscellaneous 1.7104 4/29/2009
Consent Order Amend 2017.pdf Orders/Consent Judgments 0.6545 8/10/2017 1/7/2020
Executed RDRA Consent Judgment 2020.pdf Orders/Consent Judgments 1.0511 4/15/2020 8/10/2020
Anchor-SupplementIntegratedSedimentReport-February2014.pdf Reports 4.5366 2/17/2014 11/8/2016
Site Historical Summar 2009 Text.pdf Reports 0.7613 6/11/2009 1/7/2020
Source Control Investigation 2010 partial.pdf Reports 6.4709 3/10/2010 1/7/2020
Phase II Sediment Invest. Report 2012.pdf Reports 12.5434 3/29/2012 1/7/2020
SedimentInvestigationReport December2009.pdf Reports 8.0731 12/28/2009 1/7/2020
FS Data Report 2014.pdf Reports 5.3540 11/4/2014 1/7/2020
PreDesign Investigation Report 2018.pdf Reports 9.4490 2/8/2018 1/7/2020
PGM Final Design Report_Text, Tables, & Figures.pdf Reports 12.0665 3/2/2020 12/16/2020
PGM Final Design Report_Appendix B_Specs.pdf Reports 0.9023 3/2/2020 12/16/2020
PGM Final Design Report_Appendix C_Cap Modeling.pdf Reports 4.8650 3/2/2020 12/16/2020
PGM Final Design Report_Appendix D_Erosion Eval.pdf Reports 4.8296 3/2/2020 12/16/2020
PGM Final Design Report_Appendix E_CQACP.pdf Reports 7.6985 3/2/2020 12/16/2020
PGM_Construction Monitoring_2020-12-18.pdf Reports 16.8311 12/18/2020 12/24/2020
PGM_Acceptance Survey Report Dec 2020 Abbrev.pdf Reports 12.6865 12/18/2020 12/24/2020
PGM Staff Report Final Text - October 2016.pdf RODs/Staff Reports 0.2722 10/3/2016 11/1/2016
Five Tribes Comments on Staff Report.pdf RODs/Staff Reports 0.2086 1/31/2017 3/1/2017
Yakama Final Comments on Staff Report.pdf RODs/Staff Reports 0.2442 1/31/2017 3/1/2017
Record of Decision - Text Final.pdf RODs/Staff Reports 0.3440 7/3/2017 7/5/2017
ROD Appendices Full.pdf RODs/Staff Reports 1.3875 7/3/2017 7/5/2017
PGM Staff Report Final Attachments (Part 1).pdf RODs/Staff Reports 19.4555 10/14/2016 9/7/2017
PGM Staff Report Final Attachments (Part 2).pdf RODs/Staff Reports 11.1890 10/14/2016 9/7/2017
ROD Attachments 1-18.pdf RODs/Staff Reports 14.9467 7/3/2017 9/13/2017
ROD Attachments 19a-36.pdf RODs/Staff Reports 19.1049 7/3/2017 9/13/2017
January 2017 Public Meeting Slideshow.pdf Site Diagrams 5.2223 1/17/2017 9/13/2017
Final Pre-Design Work Plan August 2017.pdf Work Plans 6.6142 8/31/2017 9/1/2017
PGM RD-RA Work Plan Final.pdf Work Plans 7.4177 7/6/2018 10/21/2018
Contractor Work Plan.pdf Work Plans 21.1375 3/27/2020 3/28/2020
Site Links
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Portland Gas Manufacturing Site Cleanup – AIR, LAND & WATER Remedial Action Blog

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Cap and cover operations
Debris removal
Dredging and water treatment
Demobilization of dredging moon pool
Work area isolation
Porewater monitoring ports for armored cap areas
Installation of porewater monitoring ports
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Department of Environmental Quality
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