Water Well Journal

September 2015

Water Well Journal

Issue link: https://read.dmtmag.com/i/557876

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Page 22 of 71

T he proper selection of materials for water well construction should be based on site-specific factors having significant impact on the complete life cycle cost of the well. Aquifer characteristics, water chem- istry and biology, corrosion potential, mechanical challenges, and material availability should be included in the evaluation. Without such guidance a well owner may select materials with a lower initial cost and end up with a significantly higher life cycle cost. Conversely, the proper selection of materials (which may have higher initial costs) can reduce life cycle costs, reduce water quality concerns, and may extend the lifespan of the well. Operation and maintenance costs of a water well far exceed the cost of construction, so changes in construction improving well efficiency or the well's lifespan is thus money well spent. Aquifer characteristics, well location, and drilling/construction processes should be considered when making de- cisions on well construction and mate- rial selection. Aquifer properties such as mineral content, cementation, and hydraulic flow characteristics should all be ascertained and incorporated into the well design. Carbonate aquifers, unconsolidated sand and gravel, poorly consolidated sandstone or shell-stone, chalk, or granitic rock all have physical proper- ties that can impact well materials and construction if not properly taken into account. Well location can also have an im- pact on how a well ages and the length of time between rehabilitations. Shallow and unconfined wells located close to surface water will have differing chemi- cal environments, particularly with re- spect to oxygen, than a highly confined aquifer. Different drilling methods are also appropriate for differing construc- tions and can have a big impact on well development. Impact of chemistry Groundwater chemistry and biology can impact the material selection process predominantly from the aspect of corrosion potential, but additionally CRITERIA continues on page 22 Example of well component damage. All photos courtesy of Water Systems Engineering. Selection should fit site and operational conditions to ensure optimal life. By Roger Miller and Martha Silks, PG WWJ September 2015 21 Twitter @WaterWellJournl

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