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| Site ID: 84 |
Site
Name: GASCO |
CERCLIS No: 027734359 |
| Address: |
7900 NW St. Helens Rd. Portland 97210 |
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County: Multnomah |
Region: Northwest |
| Other location information: |
Koppers is located at 7540 NW St. Helens RD |
| Investigation Status: |
Listed on CRL or Inventory |
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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 |
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Latitude: 45.5788 deg. | Longitude: -122.7583 deg. |
Site
Size: 35 acres |
| Other Site Names: |
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Koppers Co. - Portland |
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NW Natural Gas Co. |
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Pacific Northern Oil Co. |
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Portland Harbor Sediment Study |
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Fuel and Marine Marketing |
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Pacific Terminal Services |
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Northwest Natural |
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| General Site Description: |
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| Site History: |
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| 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. |
| Pathways: |
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| 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.
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