VALLEY GROUNDWATER – HOW IT WORKS
An overview of the cycles of water on earth, and how groundwater is one of the predominant sources of freshwater available to man is helpful in understanding why the steps and precautions Hansen Well-Do Service Inc. recommends in the construction of your new well are important. Some of these steps are placing the new well on your property, exploratory drilling, well design, well drilling methods, well construction and ultimately equipping your new well with pumping equipment. The aim of our well construction recommendations is to provide you with a product that has the highest efficiency, longest useful life and offers the greatest protection of the groundwater resource.
On our planet 99.7% of the water is unable to man. All civilizations throughout time are dependant on water. Only the remaining .3% of the water is usable by man and available from only two sources. The first source includes surface water, found in lakes, streams, and other areas where rain water can be funneled. The second source is groundwater.
Less than 3 percent of the fluid fresh water is available at any given moment on our planet. These reserves include water found in lakes and streams. The other 89% of an estimated 8 trillion acre-feet is located underground as groundwater. The fluid fresh water in lakes and streams represents water which is in transit, while groundwater sources represent water in storage. Ground water has been accumulating over centuries, with rain fall adding only slightly to its volume. During an average year water in streams is replaced an average of 31 times due to the natural cycle of water anon our planet.
Surface Water (3%)
– Snow & Glaciers
Understanding how we use technology, and the mechanics our company employs to tap the groundwater resources helps our clients make informed buying decisions ultimately helping our companies provide a superior product.
Geology dictates that different approaches be used be used to access the ground water reserves and varied types of equipment be employed. Hansen Well-Do Service Inc. has developed a methodology that is unsurpassed in constructing and developing water wells in unconsolidated alluvial sediments. Preliminary investigation of existing well records and exploratory test drilling coupled with water well design and water well construction are integral parts in a program to responsibly develop and protect ground water for our clients.
Water well efficiency and the associated costs of energy, as well as the initial cost are critical factors in calculating and determining the actual direct costs of water.
In the simplest of terms water can be pumped through fractures in consolidated rock formations, and unconsolidated sediments in deposits of alluvial / transported materials.
Consolidated Rock Formations
Penetrating consolidated formations for exploratory drilling, which includes test hole drilling, and finial well construction is accomplished by the use of direct air, down the hole hammer, casing hammer, cable tool, and to some degree direct circulation mud rotary methods.
Direct Air Circulation
High velocity compressed air is the most critical part of drilling with the direct air rotary method. Air is compressed, and forced to the bottom of the hole through the inside of a rotating drill pipe. The air expands to atmospheric pressure as it exits ports in the drill bit. In this process the drill cuttings and rock fragment are blown upwards to the surface, through the annulus between the drill pipe and inside of the bore hole.
A common tool used for direct air drilling uses a “down the hole hammer”. This tool is essentially a “Jackhammer” placed at the bottom of a drill string, operated by high pressure compressed air. The action of the hammer and bit is used to pulverize consolidated rock formations and blow the fragments and dust to the surface.
Cable Tool Drilling
The cable-tool percussion method carries out the drilling operation by repeatedly lifting and dropping a heavy string of drilling tools in the bore hole. The drill bit breaks and crushes hard rock into small fragments. When working in soft unconsolidated formations, the drill bit loosens the material. In both formations, the reciprocating action of the tools mixes the crushed or loosened particles with water to form a slurry or sludge.
The resulting slurry or sledge is removed at intervals from the borehole by a sand pump or bailer.
Casing Hammer Drilling
Casing hammer drilling pushes casing through formation as the borehole is advanced. The drill pipe is placed inside the casing with a drill bit attached. Direct air is used in much the same principle as in direct air drilling. This method of drilling allows penetration of extremely loose formations where other methods would have limited success due to lost fluid circulation.
This method of drilling requires the use of a top head drive rig equipped with a high volume air compressor.