Weyerhaeuser NR Company
Facility Site ID:
32
Cleanup Site ID:
2375
Site Information
The Site is in Cosmopolis, Washington and the main mill portion is located on the south bank of the Chehalis River. Weyerhaeuser constructed the pulp mill at the site in 1957. The mill made paper grade products until 1962, when Weyerhaeuser converted production to dissolving and specialty grade pulp. The mill made pulp by using magnesium sulfite to cook wood chips, then bleached the pulp using chlorine dioxide and other chemicals.
Weyerhaeuser operated the mill until September 2006, when production shut down. The company mothballed the facility the following year in preparation of selling the mill. In May 2011 the mill resumed operation as Cosmo Specialty Fibers (Cosmo), owned by Gores Group, LLC. In December 2022, Cosmo shut down its production and transferred ownership to Charlestown Investment. The mill has remained shut down while the new owner pursues investors to re-start mill operations. However, chemicals used for the pulping process remain stored at the site. Staffing at the site has significantly reduced during that time and both power and water were shut off in the fall of 2024. Cosmo stores about 800,000 gallons of chemicals at the site in preparation for the re-start.
Weyerhaeuser operated the mill until September 2006, when production shut down. The company mothballed the facility the following year in preparation of selling the mill. In May 2011 the mill resumed operation as Cosmo Specialty Fibers (Cosmo), owned by Gores Group, LLC. In December 2022, Cosmo shut down its production and transferred ownership to Charlestown Investment. The mill has remained shut down while the new owner pursues investors to re-start mill operations. However, chemicals used for the pulping process remain stored at the site. Staffing at the site has significantly reduced during that time and both power and water were shut off in the fall of 2024. Cosmo stores about 800,000 gallons of chemicals at the site in preparation for the re-start.
How The Site Became Contaminated
Constructed in 1957, the facility predates environmental laws and regulations, including the 1976 Resource Conservation and Recovery Act (RCRA) and the 1989 Model Toxics Control Act (MTCA). Over the years, there have been documented releases, including the following:
• Liquid chlorine leak from a chlorine car on October 27, 1979.
• Release of magnesium oxide dust from a recovery bypass valve on December 1, 1979 for a duration of 5 hours.
• Spill of about 1,000 gallons of red liquor to the stormwater system on February 6, 1980. Red liquor is a mixture of spent pulping chemicals and organics specific to the sulfite pulping process.
• Spill of sodium hydroxide from a railcar off-loading in February 1995, resulting in groundwater exceeding the pH 12.0.
• Spill of acidified water to the ponds on January 6, 1998, resulting in pH measurements as low as 1.0 in the adjacent ditches.
• About 16 leaks in the wastewater pipe over the last 10 years, with the most recent leak discovered on September 12, 2023 at the residential area. The pipe is made of wood stave and runs about 2.5 from the mill through the town of Aberdeen and Cosmopolis.
In addition to documented spills, the November 2017 Sediment Study found elevated levels of dioxin and furans in the vicinity of the mill’s outfalls.
• Liquid chlorine leak from a chlorine car on October 27, 1979.
• Release of magnesium oxide dust from a recovery bypass valve on December 1, 1979 for a duration of 5 hours.
• Spill of about 1,000 gallons of red liquor to the stormwater system on February 6, 1980. Red liquor is a mixture of spent pulping chemicals and organics specific to the sulfite pulping process.
• Spill of sodium hydroxide from a railcar off-loading in February 1995, resulting in groundwater exceeding the pH 12.0.
• Spill of acidified water to the ponds on January 6, 1998, resulting in pH measurements as low as 1.0 in the adjacent ditches.
• About 16 leaks in the wastewater pipe over the last 10 years, with the most recent leak discovered on September 12, 2023 at the residential area. The pipe is made of wood stave and runs about 2.5 from the mill through the town of Aberdeen and Cosmopolis.
In addition to documented spills, the November 2017 Sediment Study found elevated levels of dioxin and furans in the vicinity of the mill’s outfalls.
Contamination
Contamination at the site has not been fully investigated. Future remedial investigation (RI) will provide additional information on the location and types of contaminants at the site.
Documents 16
Legal 9
| Document Title | Document Date | Document Type |
| Cosmo Specialty Fibers-2nd PLP Letter-GoresGroup | 12/22/2025 | 30-Day Notice of Potential Liability |
| Cosmo Specialty Fibers - Interim Action Agreed Order | 12/22/2025 | Agreed Order Amendment |
| Cosmo-Specialty-Fibers-Agreed-Order-Weyerhaeuser | 10/29/2025 | Agreed Order |
| Cosmo-Specialty-Fibers-Draft-Agreed-Order-Cosmo | 7/18/2025 | Agreed Order |
| CosmoSpecialtyFibers-Final PLP Letter-Charlestowne | 2/27/2024 | Final Potentially Liable Person Status Letter |
| CosmoSpecialtyFibers-Final PLP Letter-Weyerhaeuser | 2/27/2024 | Final Potentially Liable Person Status Letter |
| Cosmo Specialty Fiberts Charlestown Preliminary PLP Letter | 8/1/2023 | 30-Day Notice of Potential Liability |
| Cosmo Specialty Fibers GoresGroup Preliminary PLP Letter | 8/1/2023 | 30-Day Notice of Potential Liability |
| Cosmo Specialty Fibers Weyerhaeuser Preliminary PLP Letter | 8/1/2023 | 30-Day Notice of Potential Liability |
Outreach Information 5
| Document Title | Document Date | Document Type |
| Cosmo Specialty Fibers-Interim Action Public Notice Fact Sheet | 1/8/2026 | Fact Sheet\Public Notices |
| Cosmo Specialty Fibers-Spanish Interim Action Public Notice Fact Sheet | 1/8/2026 | Fact Sheet\Public Notices |
| Cosmo-Specialty-Fibers-Draft-Public-Participation-Plan | 8/5/2025 | Public Participation Plan |
| Cosmo-Specialty-Fibers-Public-Notice-Agreed-Order-PPP | 8/5/2025 | Fact Sheet\Public Notices |
| Cosmo-Specialty-Fibers-Spanish-Fact-Sheet-AO-PPP | 8/5/2025 | Fact Sheet\Public Notices |
Technical Reports 2
| Document Title | Document Date | Document Type |
| PLP Response Letter from Gores Group | 9/20/2023 | Site Specific Administrative Document - Other (Administrative Correspondence) |
| PLP Response Letter from Weyerhaeuser | 8/31/2023 | Site Specific Administrative Document - Other (Administrative Correspondence) |
There may be more documents related to this site. To obtain documents not available electronically, you will need to make a public records request.
Contaminants 2
| Contaminant Type | Soil |
Groundwater |
Surface Water |
Air |
Sediment |
Bedrock |
|---|---|---|---|---|---|---|
| Reactive Wastes - Corrosive Wastes | C | C | ||||
| Other Contaminant - Conventional Contaminants, Inorganic | C | C |
- S
- Suspected
- C
- Confirmed Above Cleanup Levels
- B
- Below Cleanup Levels
- RA
- Remediated-Above
- RB
- Remediated-Below
- R
- Remediated
This contaminant list was based on our best information at the time it was entered. It may not reflect current conditions at the site.
Interim Action Order Comment Period
We invite you to comment on the proposed Interim Action Order for the Cosmo Specialty Fibers site. The comment period runs from 12:01 am, January 08, 2026 through 11:59 pm, February 19, 2026.
Submit comments:
Using the online comment form
Or by mail (postmarked by 11:59 pm, February 19, 2026 to:
Ha Tran
Department of Ecology
Industrial Section
P.O. Box 47600
Olympia, WA 98504-7600
Public events:
A virtual public hearing to accept oral comments will be held on February 11, 2026 at 6:00 pm on ZOOM. Register online. Registration is required. After registering, you will receive a confirmation email containing information about joining the hearing.
If you would like to be added to the list of interested parties for Cosmo Specialty Fibers and receive updates on Ecology’s Industrial Section actions at the site, contact Tara Roberts at tara.roberts@ecy.wa.gov.
When the comment period ends, we'll review the comments received and make a final decision on the documents.
View the documents:
Draft Interim Action Order Cosmo Specialty Fibers
Background:
Ecology has begun a formal cleanup at the site under MTCA through separate Agreed Orders with Cosmo Specialty Fibers (Cosmo) and Weyerhaeuser. The formal cleanup process starts with a site investigation, to be conducted by Cosmo and Weyerhaeuser under Ecology’s
oversight.
This interim action is in addition to the remedial investigation and feasibility study work required by the Agreed Orders. This order requires Cosmo, as the current site owner, to secure and stabilize the site to prevent the release of contaminants at the site. Cosmo must do several things to comply with the order, including providing adequate security and developing and implementing a site stabilization plan.
These actions are necessary to protect human health and the environment while investigating the site and preparing a more complete cleanup plan.