Is there enough data to understand the source of dioxins in the neighborhood?
We don’t have enough technical information to definitively state that T-117 is the major source of dioxin/furans in yards, but it is a likely source of dioxin/furans in some streets and where it is co-located with PCBs in yards from truck track out. Aerial deposition is another potential source of dioxin contamination to nearby streets and yards; however, at this time it has not been determined how much of this potential contamination is from T-117 versus other sources in the Lower Duwamish area.
If someone wants to request that their yard get sampled for dioxins, who do they call?
EPA, the Port and the City are responsible for further sampling within the T117 study area; however, at this time there are no plans to conduct more sampling in the yards other than some sampling that may be needed to help with cleanup design. Any sampling outside the study area would be conducted by any future responsible parties conducting a complete characterization of their contaminated site or as part of a larger organized study looking at the distribution of dioxins (or other contaminants) within the LDW source area (all 32 sq. miles) or potentially a Puget Sound-wide study area. If a private resident is concerned about dioxins or other contaminants in their yard, then they will have to pay for that sampling themselves.
How were the sampling sites identified? What was the rationale behind the sampling protocol?
Sample sites are generally selected at locations adjacent to where previous investigation work revealed elevated PCB or dioxin concentrations. Specifics for sample selection and data results are provided in the project’s Sampling Plans (at www.T117.com), or contact one of the Port/City project managers with questions.
Were the sampling sites selected to provide adequate information about PCBs and Dioxins?
We believe we have enough information to make our decisions about the T-117 cleanup boundaries. Wherever PCBs exceed the state standard for cleanup in the streets and yards, that PCB removal will remove any dioxins that are also in the soil. The T-117 cleanup is focused on PCBs in the streets and yards, as those are 1) definitely from the T-117 site (early Malarkey Asphalt activities) and 2) are a potential source of recontamination to T-117 and ultimately to the Duwamish River. However, if more information about dioxins emerges during the cleanup design or construction, it is possible that adjustments to the cleanup plan may be made.
If the City is in charge of the streets and yards, why did the last sampling results letter come from EPA?
EPA is responsible for oversight of this project and chose to send out these letters last time.
What has the City done to address the communities’ concerns about dioxins? Is the City planning any additional studies or investigations for dioxins?
The City of Seattle is firmly committed to meeting its obligations with regard to dioxins. As stewards for the citizens of Seattle and of the environment, taking responsibility for the issue begins with understanding what is contaminated because of T-117 (where we are firmly committed to remediate) and what is going on within the entire region (where we do not have control). The City has invested significant resources in sampling dedicated to understanding the science of dioxins. The City has also taken the lead on forming a partnership with the Puget Sound Clean Air Authority, Ecology, Port of Seattle, DRCC, and People for Puget Sound seeking two separate grants from EPA to study air deposition and soil concentrations in the greater central Puget Sound region.
What will be done in the meantime (before cleanup) to address residents’ concerns about contaminants in their yard?
The City is currently looking into options to address those concerns. Additionally, the Washington State Department of Health is performing a health assessment in the area. (For information about the Department of Health’s activities or for health questions, please contact Elmer Diaz, at 360-236-3357).
What is the Washington State Department of Ecology’s role in the dioxin/furans in the streets and yards?
Ecology places sites with known chemical contamination above the state’s cleanup level on the hazardous sites list for toxic cleanups. All sites on the list are ranked in priority based on the potential threat the site poses, if not cleaned up, to human health and the environment. The estimate is based on the amount of contaminants, how toxic they are, and how easily they can come in contact with people and the environment. A rank of one represents the highest level of concern relative to other sites, and a rank of five the lowest. The T-117 site (which includes the yards and streets between T-117 and 14th Avenue South, Dallas Avenue and South Donovan Street) has been assigned a priority rank of one, as have five other sites within the Lower Duwamish Waterway. Hazard ranking helps Ecology target where to spend cleanup funds. However, a site's actual impact on human health and the environment, public concern, a need for an immediate response, and available cleanup staff and funding also affect which sites get first priority for cleanup.
Have you done any sampling of the soils beyond the study area (i.e. outside South Park)?
The project limited to soil and groundwater sampling within the footprint of the affected area (the areas that were contaminated by the former asphalt plant). The distance from the site that we sampled was a most about 4 blocks away, toward the west and north.