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his hSia i-<-""*-'' i^ii't' 'f-" *-***-' ' • ay^'lsbk copy iG FiiT.i.. iltS jraadc JV f,'jsc:iji& a^sU" ahWu-j, The content of this report is effective as of July 1982.

This report contains an initial definition of the field tests proposed for the Yucca Mountain Project repository sealing program.The tests are intended to resolve various performance and emplacement concerns.Examples of concerns to be addressed include achieving selected hydrologic and structural requirements for seals, removing portions of the shaft liner, excavating keyways, emplacing cementitious and earthen seals, reducing the impact of fines on the hydraulic conductivity of fractures, efficient grouting of fracture zones, sealing of exploratory boreholes, and controlling the flow of water by using engineered designs. Ten discrete tests are proposed to address these and other concerns. These tests are divided into two groups: seal component tests and performance confirmation tests. The seal component tests are the small-scale in situ tests, the intermediate-scale borehole seal tests, the fracture grouting tests, the surface backfill tests, and the grouted rock mass tests. The seal system tests are the seepage control tests, the backfill tests, the bulkhead test in the Calico Hills unit, the large-scale shaft seal and shaft fill tests, and the remote borehole sealing tests. The tests are proposed to be performed in six discrete areas, including welded and nonwelded environments, primarily located outside the potential repository area. The final selection of sealing tests will depend on the nature of the geologic and hydrologic conditions encountered during the development of the Exploratory Studies Facility and detailed numerical analyses. Tests are likely to be performed both before and after License Application.

This report presents a strategy for sealing exploratory boreholes associated with the Yucca Mountain Site Characterization Project. Over 500existing and proposed boreholes have been considered in the development of this strategy, ranging from shallow (penetrating into alluvium only) to deep (penetrating into the groundwater table). Among the comprehensive list of recommendations are the following: Those boreholes within the potential repository boundary and penetrating through the potential repository horizon are the most significant boreholes from a perfonnance standpoint and should be sealed. Shallow boreholes are comparatively insignificant ,andrequire only nominal sealing. The primary areas in which to place seals are away from high-temperature zones at a distance from the potential repository horizon in the Paintbrush nonwelded tuff and the upper portion of the Topopah Spring Member and in the tuffaceous beds of the Calico Hills Unit. Seals should be placed prior to waste emplacement.Performance goals for borehole seals both above and below the potential repository are proposed. Detailed construction information on the boreholes that could be used for future design specifications is provided along with a description of the environmental setting, i.e., the geology, hydrology, and the in situ and thermal stress states. A borehole classification scheme based on the condition of the borehole wall in different tuffaceous units is also proposed. In addition, calculations are presented to assess the significance of the boreholes acting ,as preferential pathways for the release of radionuclides.Design calculations are presented to answer the concerns of when, where, and how to seal. As part of the strategy development, available technologies to seal exploratory boreholes (including casing removal, borehole wall reconditioning, and seal emplacement) are reviewed. It is recommended that the surface-based site characterization program maintain exploration boreholes with casing so that seals can be placed at selected sealing locations, that grout not be introduced at sealing locations, and that work plans for drilling additional boreholes be developed that address sealing issues. Borehole-specific sealing plans should also be developed. _3__TIONOF THIS DOOU ' IMIT,

A TCE-contaminated competent bedrock site in Portsmouth, NH was used to determine if a relation existed between microfracture surface geochemistry and the ecology and metabolic activity of attached microbes relative to terminal electron accepting processes (TEAPs) and TCE biodegradation. The bedrock is a metasandstone and metashale of the Silurian Kittery Formation. Eleven microfractures (MF 01-11) were extracted from cores of competent rock from 2 boreholes (BBC5 and BBC6) at depths >21.3 m below ground. The host rock had 3 nominal pore width sizes (131.1, 1.136, and 0.109 μm), a porosity of 0.8%, and a permeability of <1 μd. Microfracture surface precipitates were polycrystalline with grain sizes ranging from 10 to 100 μm. Petrography and XRD revealed that carbonates and quartz were the dominant microfracture surface precipitates. Mineral distribution was heterogeneous at the 10 μm scale. Oxidized and reduced iron species were identified with XPS on the microfracture precipitate surfaces. Carbon functional groups characteristic of NOM were also identified. SIMS mass fragment fingerprints suggested that TCE, PCE and/or VC were possibly adsorbed to NOM on the microfracture surfaces. Packer waters were alkaline (131-190 mg/L as CaCO 3 , pH 8.8 to 9.6), mildly reducing (Eh of −208 to 160 mV, DO of 0.4 to 2.5 mg/L), with low NPDOC values (0.8-1.7 mg/L), and measurable Fe (II) (0.1 mg/L) and Fe (III) (0.02 to 0.3 mg/L). Sulfate was the dominant anion in the packer sample water (110-120 mg/L). No sulfide was detected. H 2 was present in a number of the BBC wells at the site (2.2-7.3 nM). Amplification with specific primer sets of seven microfractures from BBC5 showed the presence of bacteria, Archaea, anaerobic dehalorespirers (Dehalococcoides sp.), sulfate reducing bacteria, and iron reducing bacteria (Geobacteraceae). Redox zonation may exist relative to spatial distance from within the microfracture network to the open fracture system. The microfracture surface precipitates, frequently spatially complex and comprised of a variety of C-, Fe-and S-containing minerals, may be another region for redox zonation. Fe was the dominant microfracture surface element and active Fe cycling is suspected. However, the primer data suggest that the microfracture network may have been more reducing than the open fracture system. In this case, the microfracture network may constitute a zone where more reductive metabolic processes occur, making this system similar to biogeochemical redox zones found in other environments.