Residential and upland soil sampling nears completion
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- Published: Wednesday, 17 December 2014 02:34
Residents, property owners and land managers in areas around the Northport community and up to the Canadian border have been getting a lot of attention in 2014 because of two soil sampling studies being conducted as part of the Upper Columbia River (UCR) remedial investigation and feasibility study (RI/FS).
A residential soil study is being conducted by EPA to generate analytical data for soil samples that will be used to refine exposure estimates for residents in the northernmost reaches of the UCR Study Area. This data will support the human health risk assessment (HHRA).
In January, EPA sent letters to owners of 513 properties in the sampling area inviting those with a residence on their property to have their soil sampled. Since then, 84 residences (properties) signed agreements to allow sampling on their property.
All of the properties are unique, rural properties. This required EPA to do site visits in the spring at all of the properties to map them out and decide where to take samples. EPA then came back in August to start taking soil samples. The sampling wrapped up in early October.
On a parallel track, Teck American Incorporated (TAI) under the oversight of EPA is conducting an upland soil study. Here, the objective is to evaluate if there is unacceptable risk to ecological receptors and people from exposure to metals in the upland soils. This study will serve as the foundation for the terrestrial risk assessment.
Because the sampling areas overlap, some residents volunteered to have both residential and upland soil sampling conducted on their property. In the case of residential sampling, the focus was on collecting samples where humans would most likely interact with the soil, e.g.—gardens, the drip line of a house, animal pastures and children play areas.
With upland soil sampling, the focus is on areas of deposition, either from UCR sediment deposition on relict floodplains, from smelter stacks, or re-deposition of windblown sediments during low water (drawdown) conditions.
Said Kris McCaig, the Teck manager overseeing the effort, “Working with a lot of partners, we were very pleased with the response from numerous private landowners, companies and State and Federal land managers that volunteered to have their soil sampled. Approximately 120 different land owners on 275 different parcels participate. This included large land owners who agreed to have multiple parcels sampled.”
Both studies use a methodology called incremental composite sampling for soil collection. For the upland soil sampling program, each soil increment sample is collected using hand-held tools which go to a depth of approximately three inches. In each sampling area (about 25 acres in size) approximately 30 increments of soil are collected and combined in a container to create one composite sample which is submitted for laboratory for analysis. In some of the sampling areas, three composite samples will be collected which means 90 increments of soil are collected.
For the residential soil sampling program, the 84 properties had a total of 561 increment composite samples and 413 discrete samples. This resulted in approximately 17,243 holes in the ground.
Preliminary data will start coming in this winter. For residential sampling, Laura Buelow, an EPA project manager, said “We’ll be contacting each homeowner with results specific to their property. If we get results that are of concern, we’ll contact them as soon as possible and begin considering potential early actions.”