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6 r ^ ^ soli ' ~ Well casing - Water sable Ground water rills i en spaces ~waler fable r ' ~ . ' wen screen ~\ :BEDROCK ~.. ~~:' ~ \~~ ~ ~ . Wells require casing to protect against possible contaminants at or near the ground surface. Casing may not be needed at depth in solid rock but wells in alluvial sands and gravels need casing to prevent cave-in. A well screen, or perforated casing, is specially designed to keep sand out but let water into the well. Screens can be expensive, but in some situations they are needed to ensure long term use of the well. Well Development The drilling process often uses specially formulated drilling mud to help carry the drilled pieces to the surface. iv[ost drilling also creates finely around rock material. All fine particles need to be removed from a well in order that it ma•~ efFciently produce ware:. The process of removing fine particles is called well development. Drillers usually do this by using compressed air or bailing equipment to agitate and remove water from the well until it runs clear. Proper well development is essential to have an efficient well, minimize pumping lifts and to obtain clean sand free sva~ Yield Tests Colorado requires the well driller to perform a well yield test. Test results are essential for selectirte ttte right pump and knowing the well's limitations. Ideally, water will Oow into the well at the same rate that it is removed by the pump. There are three important pieces of information needed for designing an efficient water system: the static water level, the purnpm_, "ater level at carious (low' rates, and the time it takes for the 7 water level to recover after pumping ceases. Fur low yield wells. a lung term well test is recommended. Low-Yield Wells j In some areas of Colorado, the subsurface geology is nut capable of I~ producing the amount of water normally expected from a domestic well (2-10 gallons per minute). However, will[ a properly sized storage tank or a controlled pumping system, a well producing as little as one g.p.m. can be adequate for domestic needs. Itt many domestic wells, several hundreds of gallons of water are already stored in the well. For every Coot of water in a 6 inch diameter well, there are I'/ gallons in storage. When properly designed and managed, low-yield water wells can provide a viable supply for a home. Let's use the example of a well capable of producing only one g.p.m. There are 1440 minutes in every day. If the well produced water throughout the day, 1440 gallons of water could be pumped into the storage tank. Assume that a family of four is served by the well and that each family member uses 75 gallons of water a day, or 300 gallons. Total consumption for the entire family would be less tltan'_ I percent of the water stored in the tank. The well would be required to produce wa4r orly five hours a da•- in order G, replenish the water used. Low yield wells are often hydrofraced to improve their yields. The process involves down-hole equipment that creates high pressure to open or spread cracks or fractures. HOW MUCH WATER -HOW MUCH MONEY? How Much Water Do You Need? If you plan wisely, a good, dependable water well can supply you with all the water you need now and in the ftlture. A rule of thumb is to allow for between 75 and I50 gallons per person per day. 1'ou need to take into account the peak demand, for example when there may be extra euests at holidays or week-ends. Outside use of water can pose much greater demands. You need to calculate the required well yield if your well is needed for additional water uses such as: