Dames & Moore, 1999 - USDA Forest Service

considered as part of the groundwater system based on the apparent underground source of water at most
of the.seep locations. Additionally, a limited number of seeps were more indicative of surface water flow,
but were considered seeps based on their apparent connection with seeps resulting from underground
flow. Seep locations are shown on Figure 5.4-1. Samples were collected in 1997 during sampling events
conducted in MaylJune, July, and September. Seep samples were collected during each sampling event if
measurable flow and volume were available for sample collection. Additionally, samples were collected
at select seeps in May 1998.
Groundwater samples collected from monitoring wells and seep samples were analyzed for dissolved
metals (aluminum, arsenic, barium, beryllium, cadmium, calcium, chromium, copper, iron, lead,
magnesium, manganese, mercury, molybdenum, nickel, potassium, selenium, silver, sodium, thallium,
uranium, and zinc), ortholtotal phosphorus, totallamenable cyanide, total dissolved solids, total suspended
solids,'chloride, nitratelnitrite, sulfate, alkalinity, color, and hardness as outlined in the SAPS and QAPPs
associated with each field effort (see Section 1.0). Additionally, a limited number of samples were
analyzed for organic constituents, i.e., polychlorinated biphenyls (PCBs), and TPH (gasoline, diesel, and
heavier than diesel range). The samples were analyzed by Analytical Resources Incorporated (AN)
located in Seattle, Washington. Field measurements for pH, specific conductivity, temperature,
oxidation~reduction potential, and ferrous iron were collected for each sample as outlined in the
associated SAP and QAPP.
RI analytical data are summarized in Tables 5.4-1 and 5.4-2. A copy of laboratory reports and associated
data validation and related memoranda are included in Appendix L. The data were reviewed and
validated as outlined in the associated QAPPs. Generally, the data were acceptable and met the project
objectives. Due to the total dissolved solids concentration in several samples, the metals analytical
methodology originally selected and approved in the SAPS and QAPPs for groundwater was revised to
allow analyses to proceed. Method adjustments resulted in raised detection limits for certain metals.
Generally, the increased detection limits did not affect evaluation of the data as compared to MTCA
cleanup levels or data usability for site assessment with the exception of beryllium and thallium.
Detection limits for beryllium ranged from 0.04 pgL to 20 pg/L compared to the MTCA Method B
cleanup level of 0.0203 pglL. Thallium detection limits ranged from 0.80 pg/L to 50 pg/L compared to
the MTCA Method B cleanup level of 1.12 p a. Beryllium and thallium were generally not detected.
Neither metal was identified as a compound of concern in surface water. The sample analyses were
performed such that the lowest detection limit reasonably achievable given the individual sample matrix
was obtained.
Site groundwater data collected from monitoring wells were compared to MTCA.values and applicable
criteria designated in WAC 173-200 as the groundwater underneath and in the surrounding area of
Holden Mine is not currently used as a drinking water source and is not anticipated to become a drinking
water source in the foreseeable future. Groundwater collected from a drinking water well located at
Lucerne at the USFS Guard Station was compared to MTCA and the federal maximum contaminant
levels (MCLs) for drinking water as the well supplies water for USFS volunteers and occasional visitors.
To assess PCOCs, the Site groundwater data collected from groundwater monitoring wells were
compared to the MTCA Method A cleanup levels .for If MTCA Method A levels were not
available, data were compared to MTCA Method B cleanup levels. Constituent concentrations detected
above MTCA cleanup levels were considered, PCOCs in groundwater. Calcium, magnesium, potassium,
\\DM-SEAI\VOLI\COMMOMWP\WDATAWO5\REPORTSWOLDEN-2UUU-Od 5-39
17693-005-019Uuly 28. 1999;11:09 A M D W
FlNAL RI REPORT