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Environmental Cleanup Site Information (ECSI) Database Site Summary Report - Details for Site ID 183, Siltronic Corp.

This report shows data entered as of January 19, 2021 at 11:12:56 PM

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 183, Siltronic Corp.

General Site Information

Site ID: 183 Site Name: Siltronic Corp. CERCLIS No: 096253737
Address: 7200 NW Front Ave. Portland 97210
  County: Multnomah Region: Northwest
Other location information: The Siltronic Corporation facility occupies approximately 85 acres in northwest Portland and is located on the west side of the Willamette River about 3/4-miles southeast of the St. Johns Bridge between Front Ave. and Hwy. 30 (St. Helens Rd) at the NW 7200 Block.
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 , 13 Tax Lots: 1
  Latitude: 45.5775 deg. Longitude: -122.7552 deg.  Site Size: 84.6 acres
Other Site Names:
  Portland Harbor Sediment Study
  NW Natural Site
  Wacker Siltronic
  Northwest Natural
  Portland Development Commission (PDC)

Site Characteristics

General Site Description: Wacker Siltronic Corporation purchased the property from the City of Portland in 1978 for the purpose of constructing a wafer fabrication plant. Following the sale, construction began in 1978, and production of silicon crystals for wafer manufacturing commenced in 1980. Siltronic has been producing and preparing silicon wafers at the current location since 1980. Until late-2012 the Siltronic operations included two fabrication buildings. Currently production occurs in a single building. Siltronic ships finished products to customers for use in micro-processor manufacturing.
Site History:
Contamination Information: (5/20/93 KPD/SAS) Predecessor company of Northwest Natural Gas accumulated 30,000 cubic yards of oil-gas manufactuing wastes in on-site pits. Waste pits were buried under 10 feet of overburden and spent oxide in 1973. Wacker purchased part of the property in 1978. Subsurface soil sampling on the vacant southern half of the site in 1985 found high levels of PAHs, plus lesser amounts of herbicides. Similar contamination was found in subsurface soil sampling on another portion of the site in 1990. The same year groundwater contaminated with TPH and BTEX compounds was found near a fuel line corridor. In addition, there has been occasional releases of solvents from Wacker's operations.
(1/19/00 JMW/SAP) In September and October 1997, EPA's contractor, Roy F. Weston Inc., collected sediment samples within the Portland Harbor (RM 3.5 to RM 9.5). Beryllium, cobalt, iron, manganese, selenium, silver, titanium, vanadium, zinc, carbazole, 2-methylnaphthalene, bis(2-Ethylhexyl)phthalate, dibenzofuran, Di-N-Butylphthalate, pentachlorophenol, PAHs, DDTs, 2,4-D, and 2,4-DB were detected in river sediments. Groundwater investigation detected up to 575 mg/L TCE and 6.3 mg/L vinyl chloride in groundwater at the northern portion of the facility.
(2/13/04 MJM/SRS) In July 2003, TCE was detected at ~ 20 feet below ground surface in soil (557 mg/kg) beneath the location of former TCE underground storage tank system (Former TCE UST System) also in the northern portion of the site.
(12/14/12, DSB/PHS) Siltronic's RI Report (04/07) evaluated the lateral and vertical extent of chlorinated volatile organic compounds (cVOCs) in soil and groundwater in the uplands and river sediment, transition zone water, and groundwater off-shore of the northern portion of the site. The RI Report identified two water-bearing zones (WBZs) beneath the site: 1) a shallow WBZ comprised of 25-35 feet of fill material (i.e., the Fill WBZ); and 2) a deeper WBZ in native alluvial sediments (i.e., Alluvium WBZ). Investigations completed between 2001 and 2007 identified a plume of contaminated groundwater containing trichloroethene (TCE) and its degradation products including cis-1,2-dichloroethene (cis-1,2-DCE), trans-1,1-dichloroethene (trans-1,2-DCE), 1,1-dichloroethene (1,1-DCE), and vinyl chloride; in the Alluvium WBZ. The plume occurrs between 40-120 feet below ground in the area of the Former TCE UST System and 80-160 feet near the Willamette River. Depending on location TCE concentrations ranged from greater than 100,000 parts per billion (ppb) in the Former TCE UST System area, to over 1,000 ppb near the river. The RI Report concluded the source of cVOC contamination in the Alluvium WBZ was the Former TCE UST System. Based on work completed in 2008, an additional source of TCE, including TCE dense non-aqueous phase liquid (DNAPL); was identified in the Fill WBZ upgradient (west-southwest) of the Former TCE UST System.
The portion of the Siltronic site contaminated by cVOCs occurs within a larger area of contamination associated with historic operations of the former “Gasco Facility" MGP.
Information regarding the Gasco Facility can be found at ECSI #84.
(08/16/16, DSB/CU) Investigations conducted by NW Natural between 2007 and 2010 confirmed that within and near the southern portion of the Siltronic Site, hazardous substances (e.g., total petroleum hydrocarbons, polycyclic aromatic hydrocarbons) associated with the redistribution of MGP waste and historic fuel storage and handling operations occur in soil, surface water, sediment, and groundwater. These same investigations found dense non-aqueous phase liquid (DNAPL) in areas within the southern portion of the site. Furthermore, investigations by Rhone Poulenc in the southern Siltronic Site have detected hazardous substances (e.g., pesticides) in groundwater in fill material.
Manner and Time of Release: Historic operations and past practices by Siltronic and NW Natural have caused the bulk of contamination on the Siltronic property.
According to a report prepared in 2002, TCE was used during steps in the wafer etching/lapping process, including as an ingredient in wax formulation, as a solvent in the wax mounting and wafer-polishing activities, and as a dewatering agent following wafer cleaning. The TCE was managed using the Former TCE UST System from 1980 to 1983. The Former TCE UST System was cleaned and decommissioned in-place in 1983 and later removed in 1985. An above-ground storage tank system was used to manage TCE from 1983 through 1989, at which time TCE use was discontinued by Siltronic. Siltronic estimates TCE releases occurred from the Former TCE UST System between 1980 and 1984.
Historically, Pacific Gas & Coke Company (now NW Natural) used portions of the Siltronic property as part of the “Gasco Facility” manufactured gas plant (MGP). The Gasco Facility operated from 1912 to 1956 on the property adjoining Siltronic to the north that is currently owned by NW Natural (i.e., the "Gasco Site," ECSI #84). The northern portion of the Siltronic property was used for stockpiling spent oxide material and as an effluent pond during the later stages of the Gasco Facility operations.
Wastes associated with the former GASCO MGP operations in the northern Siltronic Site were redistributed across the Siltronic Site when the property was filled between 1966 and 1975. An estimated totoal of 1,500,000 cubic yards of fill material was placed on what is now the Siltronic Site prior to site development. Approximately 700,000 cubic yards of the fill material was hydraulically dredged from the Willamette River.
Hazardous Substances/Waste Types: Chlorinated VOCs (TCE, cis-1,2-DCE, trans-1,2-DCE, 1,1-DCE, vinyl choride) associated with releases from Siltronic's historic operations; PAHs, BTEX, carbazole, dibenzofuran, phenols, cyanide, methylnaphthalenes, trimethylbenzenes, metals, and manufactured gas plant waste, including DNAPL, from historic operations of NW Natural's former "Gasco Facility;" beryllium, cobalt, iron, manganese, selenium, silver, titanium, vanadium, zinc, 2-methylnaphthalene, bis(2-ethyhexyl)phthalate, carbazole, pentachlorophenol, di-n-butylphthalate, dibenzofuran, PAHs, DDTs, 2,4-D, 2,4-DCB in adjacent Willamette River sediments.
Pathways: The site is located in a heavily industrialized part of northwest Portland. The Willamette River is adjacent to the site on the northeast, and Forest Park is less than a quarter mile to the southwest across Highway 30. Historic releases of cVOCs from Siltronic's Former TCE UST System and MGP constituents from the former Gasco Facility MGP have impacted groundwater in the Fill WBZ and Alluvium WBZ beneath the Siltronic site. In addition, cVOCs and MGP materials are present in groundwater, transition zone water, and river sediment at concentrations that exceed Joint Source Control Strategy screening criteria.
Based on the work completed by Siltronic and NW Natural, DEQ determined that groundwater in the northern portion of the Siltronic property and along the shoreline of the adjoining Gasco Site is a complete high priority contaminant transport pathway to the Willamette River that warrants source control.
Environmental/Health Threats: The Siltronic Corporation property is zoned industrial. There is a potential risk to on-site occupational, construction, and excavation workers through exposure to vapors, and soil and groundwater contamination. Groundwater is contaminated by cVOCs and MGP constituents that could significantly and adversely affect the beneficial uses of groundwater, including recharge to the Willamette River (Fill WBZ and Alluvium WBZ) and for industrial use (Alluvium WBZ).




Status of Investigative or Remedial Action: (5/20/93 KPD/SAS) Contaminated soil is 10-20 feet below ground surface, and groundwater in the area is not used. Contaminants may pose a threat to the environment, particularly the adjacent Willamette River. Similar contamination at the adjacent Northwest Natural Gas Company Site (ECSI #84) has been referred to Voluntary Cleanup and Site Response for further action. Site Assessment recommends that this site be included in those investigations.
(1/19/00 JMW/SAP) Based on initial sampling results from a river sediment quality study, the Wacker Siltronic site has been identified as a potential source of contamination to the Portland Harbor. A Strategy Recommendation was completed on October 8, 1999. Contamination in sediments and the high potential for groundwater contamination prompted DEQ to require an RI/FS for the facility (high priority). (3/1/00 JMW/SAP) Voluntary Agreement for Remedial Investigation and Source Control Measures forwarded to Wacker Siltronic Corporation on February 29, 2000.
(2/6/01 ELB/VCP) Following Wacker Siltronic Corp's refusal to sign the voluntary agreement, a Unilateral Order was issued jointly to Wacker Siltronic and Northwest Natural on October 4, 2000 (Joint Order). Both parties agreed to comply. An RI proposal was received on November 20, 2000.
(11/21/01 ELB/VCP) An RI work plan was approved in June 2001. The Phase I Remedial Investigation was initiated in August 2001; investigative efforts are ongoing. During the investigation, high levels of TCE were detected in groundwater near the location of Former TCE UST System.
(2/13/04 MJM/SRS) Wacker Siltronic Corporation initiated a remedial investigation of the TCE releases under a separate Unilateral Order issued on February 5, 2004 (TCE Order). The TCE Order is independent of the Joint Order.
(12/14/12 DSB/CU) Based on the RI and bench-scale tests, Siltronic developed a Focused Feasibility Study (FFS, 12/07) that recommended using enhanced in-situ bioremediation (EIB) to reduce cVOC contamination in groundwater. DEQ concurred with using EIB as a source area removal action. EIB is a technology that utilizes organic carbon, iron, and bacteria to reduce concentrations of chemical contaminants. Use of EIB at the Siltronic site requires two steps. The first step involves injecting a mixture of carbon and iron into the subsurface to begin degrading cVOCs and create conditions favorable to bacteria. The second step introduces a commercial culture of bacteria formulated for cVOCs into the ground. The EIB treatment media are designed to convert cVOCs into non-toxic byproducts.
Pilot studies were completed and documented in a Pilot Study Report (08/07). Delineation investigations identified TCE in groundwater in the vicinity of the Former TCE UST System at concentrations of up to 592,000 ppb between approximately 40-120 feet below ground. DEQ's groundwater removal action objective for EIB is to reduce dissolved-phase TCE concentrations to less than 11,000 ppb in the source area (i.e., less than 1% of the TCE solubility limit). The EIB treatment media are not intended to reduce concentrations of MGP constituents in groundwater.
The first phase of EIB injections occurred in the Alluvium WBZ from 11/08 to 07/09 in the area of the Former TCE UST System . A second phase of EIB injections was completed upgradient of the Former TCE UST System between 04/11 and 08/11 to place additional treatment media in cVOC contaminated groundwater (Fill WBZ and Alluvium WBZ and in MGP DNAPL with cVOCs (Fill WBZ).
(08/16/16, DSB/CU) Groundwater is being monitored within and near the treatment area at 27 wells. In December 2013 concentrations of TCE were less than 11,000 ppb in all of the wells. At over twenty of the installations TCE concentrations are less than the federal maximum contaminant level of 5 ppb. Groundwater monitoring continues to demonstrate the TCE reductions are sustainable and to assess the effectiveness of EIB at treating daughter products produced in the source area through TCE dechlorination (i.e., cis-1,2-DCE, trans-1,2-DCE, 1,1-DCE, vinyl chloride).
(08/16/16, DSB/CU) On November 20, 2015, DEQ determined that in order to expedite remedial action planning for the most contaminated portions of the Gasco and Siltronic sites, NW Natural will complete an RI/FS for the areas of the Gasco Site and the northern Siltronic Site associated with former Gasco MGP operations (i.e., the Former Gasco MGP Operable Unit). DEQ also determined that Siltronic will be responsible for completing an RI/FS and source control evaluations of the southern 40-acres of the Siltronic Site (i.e., the Southern Siltronic Site Operable Unit), and issued Unilateral Order No. OPSR-NWR-16-02 to Siltronic in August 2016 to complete this work.
Data Sources: 1) "Preliminary Report: Soil Investigation for Proposed Polysilicon Plant" by CH2M Hill, June 1985.
2) EPA CERCLA Preliminary Assessment report, by Ecology and Environment, October 1987.
3) Laboratory data from Pacific Environmental Laboratory, July 25, 1990.
4) "Findings Report: Groundwater and Soil Gas Investigation" by CH2M Hill, December 1990.
6) Doane Lake Study Area files (ECSI #36).
7) Portland Harbor Sediment Investigation Report, Roy F. Weston, Inc. for USEPA, May 1997.
8) Maul Foster & Alongi, Inc. (MFA), 2002, "Use and Management of Trichloroethene and Data Summary Report, Wacker Siltronic Corporation," December 10.
9) MFA, 2004, "Final Remedial Investigation Workplan, Siltronic Corporation Site," September 17.
10) MFA, 2005, "Supplmental Investigation Report, Siltronic Corporation Facility, 7200 NW Front Avenue, Portland, Oregon," September 8.
11) MFA, 2007, "Remedial Investigation Report, Siltronic Corporation," April 16.
12) MFA, 2007, "Enhanced In-Situ Bioremediation Pilot Study Report, Siltronic Corporation Facility, 7200 NW Front Avenue, Portland, Oregon," August 9.
13) MFA, 2007, "Focused Feasibility Study, Siltronic Corporation," October 23 (amended December 19, 2007).
14) MFA, 2008, "Revised Enchanced In-Situ Bioremediation Source Control Work Plan," October 20.
15) Hahn and Associates, Inc., 2011, "Remedial Investigation Data Summary Report, Historical Manufactured Gas Plant Activities, Siltronic Corporation Property, 7200 NW Front Avenue, Portland, Oregon," March.
16) DEQ's project files for "Siltronic Corporation" (ECSI File #183) and NW Natural "Gasco" site (ECSI File #84).

Substance Contamination Information

Substance Media Contaminated Concentration Level Date Recorded
BENZENE Groundwater 23,300 ppb 12/1/1990
BENZENE Soil 29 ppm 7/25/1990
BENZO(a)ANTHRACENE Soil 210 ppm 7/25/1990
BENZO(a)PYRENE Groundwater 760 ppb  
BENZO(a)PYRENE Soil 240 ppm 7/25/1990
BENZO(a)PYRENE Soil 120 ppm 6/1/1985
BENZO(b)FLUORANTHENE Soil 180 ppm 7/25/1990
BENZO(b)FLUORANTHENE Soil up to 120 ppm 6/1/1985
BENZO(k)FLUORANTHENE Soil 120 ppm 7/25/1990
BENZO(k)FLUORANTHENE Soil up to 120 ppm 6/1/1985
BIS(2-ETHYLHEXYL)PHTHALATE Sediment 210 - 700 ppb 9/1/1997
CARBAZOLE Sediment 170 - 3600 ppb 9/1/1997
CHRYSENE Soil 280 ppm 7/25/1990
CHRYSENE Soil 92 ppm 6/1/1985
DDT,p,p'- Sediment 570 - 380 ppb 9/1/1997
DIBENZOFURAN Sediment 160 - 3600 ppb 9/1/1997
DIMETHYLPHENOL,2,4- Groundwater 27 ppb  
DIMETHYLPHENOL,2,4- Soil 3.1 ppm  
DI-n-BUTYL PHTHALATE Sediment 21 ppb 9/1/1997
ETHYLBENZENE Groundwater 4,680 ppb 12/1/1990
INDENO(1,2,3-cd)PYRENE Soil 160 ppm 7/25/1990
INDENO(1,2,3-cd)PYRENE Soil up to 270 ppm 6/1/1985
IRON Sediment 51900 - 64500 ppm 9/1/1997
MANGANESE Sediment 863 - 909 ppm 9/1/1997
METHYLNAPHTHALENE,2- Sediment 180 - 11000 ppb 9/1/1997
PENTACHLOROPHENOL Sediment 4.6 - 11 ppb 9/1/1997
POLYAROMATIC HYDROCARBONS (PAH) Sediment LPAHs 6860 - 165600 ppb 9/1/1997
POLYAROMATIC HYDROCARBONS (PAH) Sediment HPAHs 3034 - 268800 ppb 9/1/1997
TOLUENE Groundwater 5,960 ppb 12/1/1990
VANADIUM Sediment 113 - 152 ppm 9/1/1997
ZINC Sediment 120 - 150 ppm 9/1/1997

Investigative, Remedial and Administrative Actions

Action Start Date Compl. Date Resp. Staff Lead Pgm
REMOVAL  (Primary Action) 06/28/2007   Dana Bayuk SRS
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 dana.bayuk@deq.state.or.us. If this does not work, you may contact Kim Hack (503) 229-6811, or via email at Hack.Kimberly@deq.state.or.us or contact the Northwest regional office.