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piping and decreased embankment stability resulting from greater pore pressures. 11. The objective of any grouting scheme should be to create a curtain which will act as a barrier to seepage beyond a certain longitudinal limit (a line parallel to the dam axis) such as the upstream crest of the dam. A program of drilling and grouting through the embankment using either chemical or cement grout should be effective in significantly reducing seepage flows and pressures through the bedrock. The following considerations should be made in evaluating the potential use of a grouting program: . Grouting generally has a significant positive effect on significantly reducing seepage flows. However, often a grout program will not block 100 percent of the seepage pathways. . By grouting along a line parallel to the dam axis as far upstream as feasible, the risks previously discussed related to exclusive outlet tunnel grouting are minimized or eliminated. Such a grouting scheme, if cautiously formulated to minimize the potential for hydraulic fracturing, can only produce beneficial results. Any pore pressure increases resulting from blocking existing seepage paths will occur upstream from the grout curtain (in the area of the upstream embankment and fOlUldation) where pore pressure increases are not detrimental. Any blockage of seepage paths will reduce pore pressures in the areas downstream from the curtain. Completion of the curtain will likely involve some grouting from inside of the outlet tunnel to close the curtain along its line in the vicinity of the outlet. . Cement grouting would be most effective if the reservoir level was drawn down below the level at which significant seepage. OthetWise, some of the grout would likely be lost to flowing subsurface water. If the grouting is to be petformed without drawdown of the reservoir, chemical grouts might be necessary which would significantly increase the cost of a grouting program. . As previously discussed for the lining option, further field investigations would provide valuable information which could be used in designing a grouting program. . If, as indicated by the Martin and Wood report, there are significant soluble materials filling joints and other openings, the effectiveness of a grouting program can be temporary. Grouting would fill the openings which existed at the time of grouting, but progressive dissolution could open new seepage pathways. Following is a cost estimate for a cement grouting program on the Harvey Gap dam seepage area: