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Environmental Cleanup Site Information (ECSI) Database Site Summary Report - Details for Site ID 84, GASCO

This report shows data entered as of June 19, 2018 at 10:42:29 AM

This report contains site details, organized into the following sections: 1) Site Photos (appears only if the site has photos); 2) General Site Information; 3) Site Characteristics; 4) Substance Contamination Information; 5) Investigative, Remedial and Administrative Actions; and 6) Site Environmental Controls (i.e., institutional or engineering controls; appears only if DEQ has applied one or more such controls to the site).  A key to certain acronyms and terms used in the report appears at the bottom of the page.

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Environmental Cleanup Site Information (ECSI) Database Site Summary Report - Details for Site ID 84, GASCO

General Site Information

Site ID: 84 Site Name: GASCO CERCLIS No: 027734359
Address: 7900 NW St. Helens Rd. Portland 97210
  County: Multnomah Region: Northwest
Other location information: Koppers is located at 7540 NW St. Helens RD
Investigation Status: Listed on CRL or Inventory
Brownfield Site: No NPL Site: No Orphan Site: No Study Area: No
Property: Twnshp/Range/Sect: 1N , 1W , 12 Tax Lots: 42,111,123,113,129,131,112,130
  Latitude: 45.5788 deg. Longitude: -122.7583 deg.  Site Size: 35 acres
Other Site Names:
  Koppers Co. - Portland
  NW Natural Gas Co.
  Pacific Northern Oil Co.
  Portland Harbor Sediment Study
  Fuel and Marine Marketing
  Pacific Terminal Services
  Northwest Natural

Site Characteristics

General Site Description:
Site History:
Contamination Information: (10/15/1999 ELB/VCP) Portland Gas and Coke Company (GASCO) apparently purchased the site in the 1880s, and built a gasification plant by 1913. All waste products from the gasification operations were discharged directly to the Willamette River until 1925. After 1925, tars were separated from the wastewater in settling ponds. When the plant was shut down in 1956 by GASCO's successor company, Northwest Natural Gas (NWNG), an estimated 30,000 cubic yards of coal tar had accumulated in the ponds. The ponds were buried under 10 feet of fill in 1973. Part of the site was then sold to Wacker Siltronic Corporation (see ECSI #183). Koppers Company leased an 8-acre portion of the site from NWNG in 1965 and built a coal-tar distillation plant. Waste streams of creosote and pitch were cooled and solidified in storage tanks, and apparently dumped into an on-site disposal pit. (The plant shut down in 1973 and has only been used for the bulk transfer of creosote oil and coal tar pitch since 1977). In December 1993, NWNG signed up for DEQ's Voluntary Cleanup Program. In August 1994, NWNG signed an agreement with DEQ to conduct a Remedial Investigation and Feasibility Study (RI/FS) at the site. An RI/FS workplan was submitted to DEQ in January 1995 and approved in August 1995.
Upland and near shore remedial investigation is ongoing.
Manner and Time of Release: Wastewater from tar stills and unusable petroleum by-products were discharged to the Willamette River, farmed on a portion of site, or disposed of in settling ponds on-site. Lampblack and spent iron oxide waste stored in large on-site waste piles. Time of release: 1913 to 1977.
Hazardous Substances/Waste Types: Oil gasification wastes including: tars, oil, creosote, phenols, polynuclear aromatic hydrocarbons, BTEX and lead.
Environmental/Health Threats: Contamination at the site may represent a threat to human health and the environment by migrating to the Willamette River. Evidence suggests near-shore Willamette River sediments are contaminated due to past operating practices.
Status of Investigative or Remedial Action: (10/15/1999 ELB/VCP) During the first phase of the Remedial Investigation, widespread petroleum contamination was identified in site soils, groundwater, and Willamette River sediments. Tars were identified to depths of 70 feet in the vicinity of the former tar disposal area. In the former plant site area, dense non-aqueous-phase liquids (DNAPLs) were identified at three distinct locations. Monitoring wells installed adjacent to the Willamette River detected elevated levels of benzene and naphthalene. Sediment samples were found to contain high concentrations of polynuclear aromatic hydrocarbons (PAHs) and tars. Phase I of the RI was completed in March 1996. Conceptual site models for human health and ecological risk assessments were submitted to DEQ in the fall of 1996. A Land and Water Use report and a series of technical memoranda were submitted during the summer of 1997. Phase II of the RI was completed during the fall of 1998. Groundwater contamination was detected up to 100 feet below the surface along the riverbank. A significant zone of tar contamination extending from the site to the river was also confirmed. (4/17/00 ELB/SRP) In March 2000, two cathodic protection wells that extended 400 feet into the basalt aquifer were abandoned. (9/15/00 ELB/SRP) In August 2000, a product recovery system was installed and soil sampling to support support the upland risk assessment was completed. (4/30/01 ELB/SRP) In March 2001, a source control evaluation was initiated to evaluate the potential for upland contaminants to migrate to the Willamette River at levels of concern. This evaluation is on going and includes additional near shore and bank area investigation in 2004. In 2003 NW Natural completed an evaluation of stabilization options for the river bank, an evaluation for a removal action in the upland tar pond area, and draft upland risk assessment.

(12/14/12 DBayuk/VCP) Removal action consists of a well-based hydraulic control and containment system that is also being implemented as a groundwater source-control measure along ~2,200 feet of NW Natural's and Siltronic Corporation (ECSI #183) shorelines.
Data Sources: Doane Lake Study Area file (ECSI #36), and NWR project manager files for this site.

Substance Contamination Information

Substance Media Contaminated Concentration Level Date Recorded
BENZENE Groundwater 16 ppm  
BENZENE Sediment 22 ppm  
BENZENE Soil 360 ppm  
CYANIDE (AS ION) Groundwater 11 ppm  
CYANIDE (AS ION) Soil 50.7 ppm  
NAPHTHALENE Groundwater 30 ppm  
NAPHTHALENE Sediment 5,100 ppm  
NAPHTHALENE Soil 11,000 ppm  

Investigative, Remedial and Administrative Actions

Action Start Date Compl. Date Resp. Staff Lead Pgm
REMOVAL  (Primary Action) 08/01/2012   Dana Bayuk VCP
View Full Report Showing Action History

Key to Certain Acronyms and Terms in this Report:

You may be able to obtain more information about this site by contacting Dana Bayuk at the Northwest regional office or via email at If this does not work, you may contact Gil Wistar at (503) 229-5512, or via email at or contact the Northwest regional office.