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Dames & Moore, 1999 - USDA Forest Service

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3.0 REMEDIAL INVESTIGATION METHODOLOGIES<br />

This section summarizes the scope of work presented in the Draft Work Plan and Sampling and Analysis<br />

Plans completed for the Phase 1, 11, and 111 RI. The RI field investigation techniques were designed to<br />

achieve the following data quality objectives:<br />

Characterize the physical and chemical characteristics of groundwater and surface water<br />

directly related to the Site.<br />

Characterize the interrelationship of groundwater, surface water, and metals loading to<br />

Railroad Creek and refine the Conceptual Site Model.<br />

Characterize the impact of metals loading on surface water quality in Railroad Creek.<br />

Characterize the geotechnical characteristics and stability of the tailings piles in regard to<br />

natural occurrences such as floods and earthquakes.<br />

Better define tailings pile drainage fate and transport in Railroad Creek applicable to<br />

evaluating environmental and human health and ecological risks.<br />

Evaluate existing data quality based on confirmatory sampling of various media.<br />

Field methodologies were in accordance with the Draft RIIFS Work Plan; the April 1997 and Phase I<br />

through Phase 111 SAPs; the QAPPs; and the H&S Plans listed in Section 1.0 of this report. The field<br />

program was performed using a phased approach. Successive phases were refined based on field and<br />

laboratory results from previous field efforts. Changes and refinements to the field program phases were<br />

discussed in technical sessions (which included representatives of Alumet and the Agencies) between<br />

field efforts. Consensus was reached between Alumet and the Agencies prior to implementing changes to<br />

the field program. The RI field program included the following:<br />

Surface water sampling and flow measurements<br />

Groundwaterlseep sampling and water level and flow measurements<br />

Geophysical surveys<br />

Surface and subsurface soil sampling<br />

Geologic hazards assessments<br />

Sediment sampling<br />

Ecological sampling and surveys<br />

Dye tracer survey<br />

Field screening analysis<br />

Quality assurancelquality control<br />

A brief description of the RI tasks and methodologies used in the RI field program are presented in th?s<br />

section and includes any deviations that occurred in the field as compared to the Work Plans (any<br />

deviations that occurred were verbally approved by the Agencies). A more detailed discussion is<br />

provided in the above-mentioned RI Work Plan, SAPs, and QAPPs. The locations of the areas evaluated<br />

~:\vlpdam\oo~\r~~~iho~d~n-z\riu-~~d~~<br />

17693-005419Uuly 19. <strong>1999</strong>;2:07 PM;DRAFT FINAL RI REPORT

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