Dames & Moore, 1999 - USDA Forest Service

The completeness of potential exposure pathways and exposure routes given the current land use and
expected future land use were evaluated in order to develop this exposure pathway model. A complete
exposure pathway consist. of the following four elements: (1) a source of constituent release to the
environment, (2) an environmental transport medium (e.g., air, groundwater. fugitive dust emissions, soil
runoff into water bodies, etc.), (3) a point of potential contact for receptors (also referred to as an exposure
point), and (4) a route of entry into humans, either via inhalation, ingestion, or dermal contact with the
affected medium. The presence or absence of any of these elements depends on the specific conditions
found at the Site. Those exposure pathways deemed to be potentially complete were evaluated by
comparing measured concentrations in media with the corresponding screening level criteria in the
screening level human health assessment.
The preliminary exposure pathway model is illustrated in Figure 7.1-1. Land use characteristics and each
element of the preliminary exposure pathway model, as well as the reason for selection of complete
exposure pathways, are discussed below.
Land Use Characteristics
The Holden Mine is located in the Cascade Mountain Range within the Wenatchee National Forest. The
Glacier Peak Wilderness generally bounds the Site to the west, north and south. A large portion of the
mine-related facilities and tailings are situated near the floor of a steepsided glacial valley. The Holden
Mine, the abandoned mill building, and the associated tailings are currently not utilized except on an
occasional basis by recreational users (i.e., sight-seers). A series of walking trails and roads allow physical
access to the mill area and the 1500-level mine portals.
A maintenance yard area is located immediately north of the mill facility. This area was previously utilized
for storage of transformers and petroleum hydrocarbons. The maintenance yard buildings are currently
utilized by Holden Village for equipment maintenance and storage.
Holden Village is situated immediately to the north of Railroad Creek, which generally bounds the mine
property to the north. Holden Village is an interdenominational religious retreat operated under a
Conditional Use Permit from the USFS. All of the buildings in the village are located on USFS property.
The village includes approximately 25 buildings. The buildings include a school and associated play area,
cafeteria, housing for full-time residents, dorm housing for visitors, meeting room, library, art studio, and
store. A road from Holden Village to Lucerne is used several times daily by buses operated by the village
during the summer months, and on an occasional basis by USFS vehicles. During the winter months, the
road is used less frequently and snow is plowed as possible; otherwise, tracked personnel carriers are
utilized.
According to Ms. Janet Grant, Holden Village Director, approximately 50 to 60 "long-term" staff have been
present in the village at any one time over the last 15 to 20 years. One couple reportedly stayed in Holden
Village for 20 years, leaving in 1983. Five people have stayed for over 15 years and 20 to 25 people have
stayed for 5 to 10 years. In addition, approximately 5000 to 6000 people visit the facility each year, each
staying from an average of wo to seven days.
Holden Village maintains a small vegetable garden (approximately 2000 square feet). According to Ms.
Grant, the produce harvested from the garden is primarily herbs which are used occasionally in the village
kitchen. The garden is tended as a hobby and not for sustenance purposes.
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17693d05-019Uuly 27.1999;5:16 PMDRAFT FINAL RI REPORT