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Mobilization and Demobilization Drilling and Casing Through Embankment, 600 ft @ $221ft Drilling Grout Holes, 1,000 ft @ $32/ft Permeability Testing Grout Holes, 1,000 ft @ $10/ft Grouting, 2,000 sacks @ $16/ sack Cement, 2,000 sacks @ $13/sack $ 3,500 13,200 32,000 10,000 32,000 26,000 ESTIMATED GROUTING COST $116,700 12% Engineering 20% Inspection 25% Contingency 14,000 23,340 29,180 TOTAL ESTIMAlED COST $183,220 The following considerations should be noted regarding the above cost estimate: I. The estimate is based on a customary grout hole spacing is 10 feet. 2. Since there was no geotechnical information available to us at the time of this estimate we assumed that the grouting depth would need to extend to about 10 feet below the outlet tunnel invert. Further geotechnical investigations or the initial results of the grouting program may indicate that the depths should vary from what we have assumed. Grout hole depths may be adjusted during the grouting program as patterns of grout take develop. 3. A great deal of care must be exercised to prevent hydraulic fracturing of the dam embankment if drilling tluough the embankment is performed using circulation of air or water. Normally, circulating fluid pressures are limited to no more than the overburden pressure in the drill hole to minimize the potential for hydraulic fracturing of the embankment/foundation. Therefore, we would recommend that grout hole drilling be performed using hollow stem augers. Some grout hole wall sealing will occur, but this method eliminates the potential for hydraulic fracturing. Grout pressures must also be carefully controlled to minimize the potential for fracturing of the bedrock and increasing the seepage problems. 4. This cost estimate is based on using a cement-based grout medium. We suggest that a small percentage of bentonite be added to the mixture to maximize long-term plasticity and minimize grout permeability. It would also be advisable to add a high-range water reducing agent during the initial stages of grouting any permeable zones encountered in order to minimize initial grout viscosity, maximize grout travel distance and maximize long-tenn grout strength. If there is enough flowing subswface water to make effective grout injection difficult chemical grouts which are not as susceptible to flushing may be required in some locations. The additional cost of using chemical grouts is not include in the above estimate.