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FAQ: OU-A Remedial Action Plan
In August 2008, the Department of Toxic Substances Control (DTSC) approved the Remedial Action Plan (RAP) for the Coastal Trail Operable Unit A portion of the Fort Bragg Mill Site.
Commonly asked questions about the cleanup plan approved in the OU-A RAP are answered here, and you can ask project staff directly by stopping by the Project Visitor Center. The Project Center is located at 215 South Main Street in Fort Bragg.
To view an interactive map of the mill site, visit the Operable Unit Map Tour.
Click on a question below to see its answer, or scroll down to view all FAQs.
Will all contaminated soils be stored on site?
Will the liner used in the containment cell remain effective over the long term?
Wouldn´t a thicker or even double liner be better?
Can the 1.6-acre capped area be safely used for anything in the future?
Will dioxin-containing soils consolidated on site be safe over the long term?
Can bioremediation be used to treat dioxins in soil?
Why not transport dioxin-containing soils to an offsite landfill?
Are sands and sediments in the intertidal zone (beach, shoreline) hazardous?
Would slowing down the cleanup process help create a more effective solution?
Will all contaminated soils be stored on site?
No. Soils excavated from the OU-A containing lead and PCBs (polychlorinated biphenyls) above DTSC-approved cleanup levels will be trucked offsite to licensed landfills. These soils have contamination at levels that cause them to be classified as regulated "hazardous wastes" and will not be disposed of onsite. Trucks will follow DTSC-approved routes out of Fort Bragg, along Highway 20 to Route 101, then south to landfills near the Bay Area or in southern California.
The OU-A soils that are targeted for remediation because of the presence of dioxins have concentrations 100 times less than the threshold for "hazardous waste." In fact, the concentrations are on average only marginally above risk-based levels considered safe by DTSC. The dioxin-containing soils will be consolidated onsite and isolated from human and ecological exposure in an engineered, impermeable consolidation cell constructed below the ground surface but well above the water table.
Will the liner used in the containment cell remain effective over the long term?
Yes. The 40-mil liner placed in the consolidation cell below and around the dioxin-containing soils (so as to isolate those soils from the environment) is expected to last a minimum of 300 years but will likely last 1,000 years or more.
To put this in local context, recall that the City Council recently considered a ban on plastic grocery bags. Those bags are much, much thinner than the liner material (less than 1 mil thick versus the proposed 40-mil liner), yet the grocery bags are routinely described as never degrading in a landfill setting.
Conditions are ideal in Fort Bragg for a long liner life. The liner will not be exposed to sunlight/UV rays (it will be covered with soil), the climate has no extremes in temperature and the material encapsulated (soils and ash with dioxins only) is not chemically reactive so it will not degrade the liner.
Wouldn´t a thicker or even double liner be better?
No, a thicker liner would not be effective. The flexible nature of the 40-mil material allows it to move if settlement occurs or there are seismic events. Further, a "double" liner as some have proposed would not improve performance of the containment system. Having two layers adjacent to one another could actually decrease the liner life if water or air were to get trapped between the layers.
A single liner is a proven and reliable barrier because very strict protocols are used for testing the seams and overall integrity of the liner during installation. The manufacturer provides specialized personnel to oversee the installation, and Georgia-Pacific and DTSC provide additional quality control requirements and oversight.
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Can the 1.6-acre capped area be safely used for anything in the future?
Yes. A variety of land uses are compatible with the soil consolidation cell after it is filled and covered with additional liner material and 18 inches of soil. For example, because the cell will be below the ground surface the area could be used for parking or roadways, open space, recreational facilities (such as ball fields) or commercial buildings if their slab foundations are designed to not penetrate or otherwise impair the consolidation cell. Similar remedial actions have been approved by DTSC in communities throughout California. And since the excavated soils will be entirely contained within the liner and under the engineered cap, there would be no exposure to people or animals.
Read information about the ongoing Mill Site Specific Plan process. As part of this process, a variety of future land uses for the OU-A Coastal Trail property and the entire mill site are being explored.
Will dioxin-containing soils consolidated on site be safe over the long term?
Yes. Dioxin molecules bind strongly to soil particles, making them largely immobile in the environment. Even if they were not encapsulated within the sealed liner of an engineered consolidation cell, the soil and dioxins would stay put. The liner system provides an extra measure of safety and will prevent rain water, groundwater or seawater from seeping into the cell. A drainage system installed in the cell will allow any accumulated liquid to be monitored and removed as necessary.
See a cross-section drawing of the engineered consolidation cell and capping system.
Under DTSC oversight, Georgia-Pacific will maintain and inspect the cap, and wells near the cell will be monitored for any unexpected impacts to groundwater. Land use controls (i.e., a deed restriction recorded with the County Assessor´s office as well as a written operations and maintenance plan) will also be used to prevent activities that might damage the cap or cell, such as digging, driving posts or other subsurface activity. Heavy-gauge wire mesh will prevent burrowing by animals and mark the location of the cap.
DTSC´s standard practice also requires a financial assurance mechanism such as a letter of credit or corporate guarantee to provide long-term funding so that the cell, cap and monitoring program can be maintained
over time.
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Can bioremediation be used to treat dioxins in soil?
At present, no. The DTSC and other treatment scientists consider bioremediation of dioxins in soil to be an unproven and thus far ineffective technology.
However, DTSC, Georgia-Pacific, and the City of Fort Bragg are working cooperatively along with DTSC′s Office of Pollution Prevention and Technology Development (OPPTD) to look further into the possible future use of fungus/mushrooms for bioremediation and are exploring a demonstration project. Georgia-Pacific is always willing to consider ideas for treatment of contaminants if the approach is compliant with regulations and effective in protecting human health and the environment.
Why not transport dioxin-containing soils to an offsite landfill?
Targeted soils are not considered hazardous waste. Soils to be excavated from the locations specified in the OU-A RAP do not have dioxin concentrations high enough to be managed as hazardous waste under either state or federal law. They therefore do not need to be disposed of in an offsite licensed landfill. In fact, although these soils marginally exceed site-specific risk-based levels, the dioxin concentrations are 100 times lower than what DTSC considers hazardous waste. To permanently prevent exposure, they can be effectively consolidated onsite within the 1.6-acre sealed consolidation cell.
Transporting soils offsite comes with its own risks. About 1,000 truckloads would be needed to carry the soils to landfills, adding up to hundreds of thousands of miles on local and state roads, causing unnecessary wear on the roads. Traveling the roads between Fort Bragg and the Bay Area landfills also increases traffic and the likelihood of accidents.
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Are sands and sediments in the intertidal zone (beach, shoreline) hazardous?
No. Testing of near-shore sand and sediment indicates that wading, swimming or playing on the beaches is perfectly safe for the public once the Coastal Trail is extended to areas such as Glass Beach.
A report of findings from sampling in the intertidal zone is available for reading at the Project Visitor Center in Fort Bragg or on the Technical Reports page.
Would slowing down the cleanup process help create a more effective solution?
No. Indeed, remedial planning and cleanup projects at the mill site have been underway for several years. The longer cleanup is delayed, the longer it will take to redevelop the site, and redevelopment is critical to returning the site to productive use, generating economic value in the community through jobs, housing, tourism and other benefits. We also want to continue to move forward with cleanup activities to effectively and expeditiously address potential environmental risks posed by onsite conditions.
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