New Well Field Investigation and Design


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New Well Field Investigation and Design

Groundwater can provide a safe and reliable source of high-quality water for potable, irrigation and industrial purposes. Groundwater sources are generally more drought resistant and are better protected from pathogenic microorganisms and contamination than sources derived from surface waters. Groundwater supply evaluations are multifaceted and typically include logistic (siting requirements), economic (cost benefit analysis) and technical (groundwater availability) issues.  Key logistical considerations include but are not limited to site development costs (i.e. infrastructure and property acquisition); regulatory siting requirements; proximity of adjacent groundwater users; and the proximity of known or potential groundwater contamination sources. Hydrogeological considerations include the physical and hydraulic characteristics of the aquifer, available recharge, sustainable aquifer yield, groundwater quality, and seasonal groundwater fluctuations.

In 2018, Cox-Colvin was retained by a public water utility to evaluate the groundwater development potential of a possible well field expansion site.  Cox-Colvin designed and implemented a test drilling plan to characterize the site geology and determine the thickness and extent of the aquifer.  Several of the test borings were completed as observation wells for the purpose of monitoring groundwater quality and water levels.

To evaluate the groundwater development potential, estimated yields were calculated for hypothetical production wells installed at various locations across the site.  Well depths, screen lengths and screen slot sizes were estimated from boring log information and sieve analysis data.  The evaluation involved several key factors including the physical and hydraulic characteristics of the aquifer, available drawdown, natural recharge limitations, induced infiltration from surface water sources, and mutual interferences caused by simultaneous pumping of adjacent production wells.  The project findings indicate the Site can be economically developed with a series of vertical wells to meet the client’s capacity needs.