Site Overview
The site is located near the center of the city of Plummer in Benewah County, Idaho. The site is
land that was historically used for wood treating operations. On the east side of
the site and to the north of Pole Yard Road is a structure that was identified by City of Plummer
representatives during a site visit as a former wood pole treating building and to the northwest
of this building is a partially intact concrete aboveground structure believe to be related to historic wood treating operations.
Site History
During the late 1950s and early 1960s, Union Pacific Railroad leased a portion of
the site set aside for a railroad depot to support a variety of industrial wood
products operators that conducted activities such as pole peeling and wood utility pole treating.
It is suspected that the wooden poles were treated with a chemical mixture of creosote and pentachlorophenol (PCP) in diesel. Wood treatment chemicals were stored in an
aboveground storage tank (AST) with an estimated capacity of 1,000 gallons. The treatment
chemicals were pumped from this AST to one of two wood pole treatment tanks. One tank
reportedly had a horizontal orientation and was used to chemically treat the body of wooden
poles; the other reportedly was vertically oriented and was used to chemically treat the ends of
the poles. After treatment, residual wood treatment chemicals were pumped back into the AST
and the treated poles were allowed to air dry. All wood treating operations were dismantled
during the 1960s, and related equipment was disposed of at an unknown location off site (PRC
1993). The locations of treatment tanks and pole drying areas are not known.
Previous assessment activities
October 6, 1993 – EPA conducted a Preliminary Assessment (PA).
November 6, 2019 – EPA conducted a Phase I Environmental Site
Assessment (ESA) at the request of the City of Plummer.
July 27 – 30, 2020 – EPA conducted a Targeted Brownfields Assessment (TBA). The EPA led TBA field sampling event included collecting a total of 32 subsurface
samples from 16 borings; two soil gas samples from two borings;
16 grab surface soil samples; six ISM surface soil samples; six
surface water samples; 13 sediment samples; and one
groundwater sample.
Analytical results indicate the presence of PAHs and creosote oil at the former creosote
AST/vault (concrete structure) and in the central ditch, as well as at downstream locations in Plummer Creek. It
appears likely that a ditch leading from the former creosote AST/vault to the central ditch has
provided a conduit for contamination in this area to reach Plummer Creek. Additionally, several
suspected treated pole drying areas, particularly those near the former creosote AST/vault and
northward, contained several PAH detections.
Removal Site Evaluation
EPA mobilized to the site on July 7, 2021 to conduct a Removal Site Assessment. EPA divided existing site decision units into 35 subunit to collect composite samples from pre-defined intervals. Samples collected included 56 composite soil
samples, 24 grab soil samples, one sediment sample, and one waste
characterization sample. Samples of surface and subsurface soil collected
by EPA during the RSE detected concentrations of polycyclic aromatic
hydrocarbons (PAHs) exceeding EPA Removal Management Levels (RMLs) for residential and industrial exposure scenarios. Analytical results from
samples collected from 11 of 31 sub-units across six Decision Units (DUs) indicate
concentrations above the EPA RMLs for Residential Soils; 2 of 31 sub-units
across two DUs indicate concentrations above the EPA RMLs for Industrial Soils.
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