GROUND WATER LEVEL TRENDS NEAR THE PROPOSED YUCCA MOUNTAIN RADIOACTIVE WASTE REPOSITORY

Statistical evaluation of available data suggests that historical ground water levels near Yucca Mountain, the site of the Department of Energy's proposed high level radioactive waste repository, have been remarkably stable for at least 20 years and that short-term variability falls within ranges expected due to earth tidal forces and atmospheric pressure changes. An analysis of the most recently available level data collected between 2001 and 2005 supports the concept of historically stable ground water levels in deep wells in the upper and lower volcanic flow system near Yucca Mountain, although some wells are apparently exhibiting rising trends. The mean fluctuation range of quarterly-measured ground water levels in 29 Yucca Mountain boreholes in the volcanic, carbonate, and alluvial flow systems comprising the periodic network for the mid 2001 – late 2005 period was 2.52 feet. The mean beginning-to-end-of-period change of quarterly-measured ground water levels from all flow system wells from the 2nd Quarter 2001 to the 4th Quarter 2005 was + 0.59 feet. When the effects of short-term rises in 3 shallow, alluvial boreholes is removed, total fluctuations and beginning-to-end-of-period changes in deeper boreholes near the site of the proposed repository become are even smaller.