Final Site Information Package for National Remedy Review Board ...
Final Site Information Package for National Remedy Review Board ...
Final Site Information Package for National Remedy Review Board ...
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SITE INFORMATION PACKAGE FOR NATIONAL REMEDY REVIEW BOARD<br />
PART B, SECTION 4: SITE CHARACTERISTICS<br />
4.2 Contaminant Fate and Transport<br />
Contaminant fate and transport in<strong>for</strong>mation provided in this section <strong>for</strong> Upper Basin<br />
surface water and groundwater is based on the additional studies conducted and data<br />
collected since the 2001 RI/FS (USEPA, 2001c, 2001d), the 2001 NRRB Presentation<br />
<strong>In<strong>for</strong>mation</strong> (USEPA, 2001b; see Supplemental CD, File B2-1), and the 2002 ROD <strong>for</strong> OU 3<br />
(USEPA, 2002). Contaminant releases within the Upper Basin are controlled primarily by the<br />
movement of surface water and groundwater within the environmental system. Primary<br />
release mechanisms are defined as acting on primary sources and secondary release<br />
mechanisms as acting on secondary sources. Surface water monitoring has shown that the<br />
Upper Basin and the SFCDR are the source of the majority of the dissolved zinc in the Coeur<br />
d’Alene River at Harrison, the downstream point in the Lower Basin where the Coeur<br />
d’Alene River enters Coeur d’Alene Lake. In the Upper Basin, contaminant fate and<br />
transport are affected by the following:<br />
• The physical setting, which dictates the movement and interaction of surface water and<br />
groundwater<br />
• The physical and chemical properties of the COCs present<br />
• Sources and mechanisms <strong>for</strong> releases of contaminants to surface water and groundwater<br />
This section includes discussions of surface water quality (Section 4.2.1) and groundwater<br />
quality and the impact of groundwater on surface water in the key alluvial areas in the<br />
Upper Basin (Woodland Park, Osburn Flats, and OU 2) (Section 4.2.2).<br />
4.2.1 Surface Water Quality<br />
Indicator contaminants <strong>for</strong> surface water quality in the Upper Basin are dissolved zinc and<br />
total (or particulate) lead. 1 For the FFS analyses (USEPA, 2010), the entire Upper Basin was<br />
evaluated as a comprehensive system, with data gathered from multiple surface water<br />
monitoring locations as shown in Figure B4-1.<br />
Extensive monitoring of the Upper Basin has been conducted, beginning in the early 1990s<br />
and continuing to the present time. This has included data collection <strong>for</strong> the RI/FSs <strong>for</strong> the<br />
Bunker Hill Box and OU 3. Additional data have been collected as part of the OU 2 EMP, the<br />
OU 3 BEMP, the Coeur d’Alene Basin Remedial Action Monitoring Program, and sitespecific<br />
studies (see Figures B2-1 and B2-2).<br />
For evaluating dissolved zinc throughout the Upper Basin, these data were used to calculate<br />
SFCDR site-specific AWQC ratios, which are used as an indicator of surface water quality.<br />
The AWQC ratio is the concentration of a chemical in surface water divided by the ambient<br />
water quality criterion <strong>for</strong> that chemical. An AWQC ratio of one or less indicates that the<br />
water quality criteria are met. The AWQC ratios are less variable than measured<br />
concentrations or calculated loads, and are not correlated with discharge except at very high<br />
1 Dissolved zinc is considered an appropriate indicator <strong>for</strong> dissolved metals because it is the most ubiquitous of<br />
the metals; it occurs at the highest concentrations and AWQC ratios; it is relatively mobile compared to other<br />
metals; and dissolved metals (particularly cadmium) appear well correlated with dissolved zinc throughout the<br />
Upper Basin (USEPA, 2001d).<br />
B4-4