Dames & Moore, 1999 - USDA Forest Service

Also included in WAC 173-201A are parameters that are not metals but which are measured and assessed
in surface water bodies. These include chloride. cyanide, dissolved oxygen, temperature, pH, and
turbidity. Site data were compared to the criteria for these parameters as well as the WQC for metals.
Freshwater AWQC and CWQC have not been established for other metals including: aluminum, barium.
calcium, magnesium, manganese, molybdenum, potassium, sodium, thallium, and uranium. Calcium.
magnesium, potassium, and sodium are considered nutrient metals and were not considered as part of the
PCOC evaluation. Area background metal concentrations for the remaining metals were used to assess
downstream Railroad Creek surface water concentrations of these metals. '
MTCA Method B surface water levels are also available and are derived for protection of human health
rather than the protection of aquatic life. In general, metal concentrations for aquatic life criteria are more
conservative than the MTCA criteria; therefore, the MTCA Method B levels were considered further for
PCOC assessment only for those metals where aquatic life criteria were not available. Evaluation of the
MTCA Method B levels are addressed in the human health risk assessment in Section 7.0.
5.1.3 Groundwater
Groundwater in and around the Site is not used as a source of potable water. The Holden Village
community water source is supplied by Copper Creek upgradient of Holden Mine-related mining
influences. The use of groundwater beneath the tailings as a potable source is not anticipated in the future
due to readily available surface water in Copper Creek as a potable water supply source. Currently, in the
Railroad Creek drainage, the use of groundwater as a potable water supply is limited to Lucerne at the
mouth of Railroad Creek.
It was not possible to fully assess representative background groundwater quality at the Site due to the
complex hydrogeologic conditions and physical characteristics of the area. Groundwater occurs in both
bedrock and the overlying glacial soil and alluvium. Groundwater was collected from wells and seeps
located outside of the observed influence of the Holden Mine and believed to be representative of
background groundwater quality. The majority of groundwater data collected was from wells and seeps
located directly within the influence of the Holden Mine andlor in direct contact with tailings material.
Background water quality and Site data are discussed in Section 5.4.
Groundwater quality data were compared to MTCA Method A and Method B groundwater cleanup levels
(Table 5.1-1). Groundwater collected at Lucerne was also compared to EPA maximum and secondary
MCLs. Additionally, groundwater data were compared to conventional and field parameter criteria
specified in Washington State groundwater standards (WAC 173-200) for nitrate, chloride, sulfate, total
dissolved solids, pH, and color.
5.1.4 Sediment
Limited background sediment data from 1994 is available upstream of the Site in Railroad Creek and in
Holden Creek (USGS, 1994). Sediment samples were collected during the RI from the Lucerne Bar in Lake
Chelan and from a reference location in Stehekin. Additionally, solid samples not characteristic of
sediments were collected at the Site during the RI and historically. These matrices included flocculent,
ferricrete, portal film, and concentrate.
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