Bedrock wells

Figure 1. Schematic diagram showing the monitoring system. (A) recompleted well, (B) surface holding pond with WW monitor, (C) WX/WY deep bedrock wells.

USA Nevada Cetchell Main Pit 6 groundwater sites USA Nevada Lone Tree Mine USA New Hampshire 30 domestic bedrock wells USA New Hampshire 937 analyses... 

Brown, C.J. and Chute S.K. (2001) Arsenic in Bedrock Wells in Connecticut. USGS Workshop on Arsenic in the Environment, February 21-22, 2001, Denver, CO. 

Juntunen, R., Vartiainen, S. and Pullinen, A. (2004) Arsenic in water from drilled bedrock wells in Pirkanmaa, in Arseeni Suomen Luonnossa Ymparistovaikutukset Ja Riskit(Arsenic in Finland Distribution, environmental impacts and risks) (eds R. K., Loukola and P. Lahermo), Geologian Tutkimuskeskus, Espoo, pp. 111-22. 

Montgomery, D.L., Ayotte, J.D., Carroll, P.R. and Hamlin, P. (2003) Arsenic Concentrations in Private Bedrock Wells in Southeastern New Hampshire, U.S. Geological Survey Fact Sheet, p. 6. 

Constltnent Nine bedrock and alluvial wells contaminated by Area 4 leachate Uncontaminated bedrock well MW97-17R UncoDtaminated alluvial well MW95-7S... 

Also, a series of near surface bedrock wells was installed in the bedrock (less than 75 feet in depth) to monitor the upper most aquifer. 

After the bedrock is exposed and clean, the next procedure is drilling. The productivity of large rotary and percussion drilling rigs is such that these rigs have largely replaced lower capacity well ddUs. 

Passive perimeter gas control systems are designed to alter the path of contaminant flow through the use of trenches or wells, and typically include synthetic flexible membrane liners (FMLs) and/or natural clays as containment materials. The membrane is held in place by a backfilled trench, the depth of which is determined by the distance to a limiting structure, such as groundwater or bedrock. A permeable trench installation functions to direct lateral migration to the surface, where the gases can be vented (if acceptable) or collected and conveyed to a treatment system (Figure 10a and 10b). 

Table II summarizes analytical data for dissolved inorganic matter in a number of natural water sources (J3, 9, J 9, 20, 21). Because of the interaction of rainwater with soil and surface minerals, waters in lakes, rivers and shallow wells (<50m) are quite different and vary considerably from one location to another. Nevertheless, the table gives a useful picture of how the composition of natural water changes in the sequence rain ->- surface water deep bedrock water in a granitic environment. Changes with depth may be considerable as illustrated by the Stripa mine studies (22) and other recent surveys (23). Typical changes are an increase in pH and decrease in total carbonate (coupled), a decrease in 02 and Eh (coupled), and an increase in dissolved inorganic constituents. The total salt concentration can vary by a factor of 10-100 with depth in the same borehole as a consequence of the presence of strata with relict sea water. Pockets with such water seem to be common in Scandinavian granite at >100 m depth.

A general conclusion from the review of the distribution of plutonium between different compartments of the ecosystem was that the enrichment of plutonium from water to food was fairly well compensated for by man s metabolic discrimination against plutonium. Therefore, under the conditions described above, it may be concluded that plutonium from a nuclear waste repository in deep granite bedrock is not likely to reach man in concentrations exceeding permissible levels. However, considering the uncertainties in the input equilibrium constants, the site-specific Kd-values and the very approximate transport equation, the effects of the decay products, etc. — as well as the crude assumptions in the above example — extensive research efforts are needed before the safety of a nuclear waste repository can be scientifically proven. 

Reg soils are closely associated with desertic regions. They have developed on stable surfaces where coarse, gravelly desert alluvium is exposed, and are characterized by a well-developed desert pavement and exhibit some well-defined soil horizons. They occur mostly on depositional surfaces where stones and gravels have been deposited since Neogene times. The surfaces commonly consist of stony, unconsolidated sedimentary deposits in which limestone, dolomite, chalk, flint and marl predominate, together with some fines (silt and clay). Sandstone and granite debris have also been reported to contribute to Reg formation. Less frequently, they form on sedimentary bedrock (Fig. 1.5). 

Much of the bedrock is covered with up to 3 m of a sandy till deposited during a southeast to northwest ice-flow event. Soil formed on the glacial sediment is typically a well-drained brunisol. 

Groundwater samples are collected from domestic wells on a regular 10x10 km grid. One sample within each grid node is collected from a well finished in bedrock and another from overburden. 

New Brunswick s bedrock geology is well mapped and largely well understood. Because of NB s mineral wealth, a great deal of mineral exploration work has been carried out since the 1950s. The bedrock in NB is also diverse in age. The oldest Precambrian rocks can be found in the Saint John area, whereas some of the younger ones, in the form or Triassic basalts, occupy more than half of the Island of Grand Manan. Most of NB s rocks are of Middle Paleozoic age. The triangle between Moncton, Fredericton, and Bathurst is occupied by a thick sequence of Carboniferous rocks that host... 

---