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Click on word or picture links for more information. We either grow it or we mine it.
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Ground water committee meeting of Jan 29 2004 |
| Ground Water Committee
In response to Dr. Gertsch's presentation, Mine-or-ours.info has begun to organize a ground water committee in search of answers to how a mine (should there be one) will affect the ground water and wells of our community. This group of local citizens and company representatives will work together to gather and provide information to those who need to make decisions about this complex issue. Meetings will be announced and open to the public. Gathered information will be posted on our web site and in the Journal as much as possible. The first questions to be considered are. As mine exploration continues and if mining begins how many aquifers will be encountered? What kind are they? How big are they? How do they interrelate? How many wells do they affect? What do we know about them already? How can we find out more? What methods of dealing with ground water are being considered? Are there other methods that might work better? What systems will be used to protect ground water from acid drainage and heavy metals? Have any of these systems failed and Why? How does blasting affect ground water? Who sets the standards for allowable limits and how will they be monitored? Who will be gathering more information and how will it be funded? If you have other questions about ground water or this committee please contact us. Ground water committee meeting of Jan 29 2004 A public meeting to address how a mine (should there be one) and mine
exploration activities will affect the ground water and wells of our community,
will be held on Thursday Jan 29th 2004. It will be at the Maple Air Apartments
Activity center, E 838 Gerue St. in Stephenson from 4-5:30 PM.
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How can we protect our
Groundwater?
This very complex issue will be a three part series. For our first installment, to give us a little background, we turn to: Robert Mahin, Senior Geologist, Minerals Processing Corporation. "Groundwater is a valuable resource and groundwater quality is one of the most important environmental issues facing the world today. In order to protect our groundwater, we first need to understand how it works. This is a field of geology called groundwater hydrology or hydrogeology. How water occurs and moves underground is not always clear. A common misconception is that groundwater collects in cavernous underground lakes or flows in underground rivers. Actually, it’s like a sponge—with the groundwater saturating pore space and thin cracks in rocks. Nor does groundwater flow like a stream--it moves by diffusing relatively slowly through the rock much like water would seep out of our sponge if it were over-saturated. A layer of rock or sediment that contains groundwater is called an aquifer. An aquifer may be layer of unconsolidated (relatively loose) sand and gravel, or solid rock like sandstone, limestone, or granite. An aquifer may be only a few or tens of feet thick to hundreds of feet thick. It may lie a few feet below the land surface to thousands of feet below. It may underlie thousands of square miles to just a few acres. And there can be different aquifers at different depths, thickness, and extent that are separated by impermeable layers of rock. The water table is the top level of the highest saturated aquifer. Where the water table reaches the surface of the ground, a spring may be found. Groundwater is replenished by precipitation and, depending on the local climate and geology, is unevenly distributed in both quantity and quality. When rain falls or snow melts, some of the water evaporates, some is taken up by plants, some flows overland and collects in streams, and some infiltrates into aquifers to become groundwater. Groundwater travels through an aquifer only if there are sufficient connected openings, or permeability, in the rock and if there is enough pressure to push it along. How fast groundwater migrates depends on how permeable the aquifer is. An aquifer made of a rock such as fractured sandstone with bigger openings permits water to move more freely than say, a granite with a fine fractures. Groundwater moves slowly, from less than a foot per day to tens or hundreds of feet per day. In Menominee County, most household water wells are less than 50 feet deep and pump from aquifers that consist of unconsolidated sand and gravel deposited by glaciers. Some wells are deeper and draw water from limestone or sandstone aquifers. In very isolated parts of western Menominee County, the glacial sands, sandstone, and limestone that provide water for most of the county thin out and in some areas disappear altogether, exposing a very different and much older metamorphosed volcanic rock. Elsewhere in the county this volcanic rock exists hundreds to thousands of feet deep below the sandstone, limestone and glacial sediments. This rock is largely impermeable and contains very little porosity, rendering it virtually useless as a groundwater resource. It is these rocks that Minerals Processing Corporation is studying for its mineral content. By understanding how groundwater moves and where it occurs, we can preserve this most precious of resources. For more information on groundwater visit the U.S. Geological Survey website at http://water.usgs.gov/ " |
Troubled waters on rise
in Colorado
By Todd Hartman, Rocky Mountain News
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| What is the difference between a confined and a water-table (unconfined) aquifer? | A confined aquifer is an aquifer below the land surface that is saturated with water. Layers of impermeable material are both above and below the aquifer, causing it to be under pressure so that when the aquifer is penetrated by a well, the water will rise above the top of the aquifer. A water-table, or unconfined, aquifer is an aquifer whose upper water surface (water table) is at atmospheric pressure, and thus is able to rise and fall. Water-table aquifers are usually closer to the Earth's surface than confined aquifers are, and as such are impacted by drought conditions sooner than confined aquifers http://interactive2.usgs.gov/faq/get_answer.asp?id=543 |
| What is an artesian well? | An artesian well taps a confined aquifer. This aquifer is a water-bearing geologic material below ground that is surrounded by other rock or material that does not allow water to pass through easily. The surrounding material may add pressure on the aquifer, and water in this aquifer can be pushed up the well, sometimes all the way to the surface, creating a flowing well. http://water.usgs.gov/ |
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