An Aquifer Is / An Aquitard is

An aquifer is a water saturated permeable geologic layer, or fracture zone, that is able to transmit significant quantities of water.  A geologic layer that cannot transmit significant quantities of water is usually referred to as an aquiclude.  An aquitard is a rock unit that generally has a low permeability and hence will transmit only very limited quantities of water and are generally not suitable for production wells.  The terms Aquifer or aquitards can be used to define most geologic strata.  The most common aquifers include permeable sedimentary rocks such as sandstones, limestone’s, sand and gravel layers, and highly fractured volcanic and crystalline rocks.  Common aquitards are un-fractured shale’s, clays and dense (un-fractured) crystalline rocks.

Sedimentary aquifers form layers and usually have a large lateral extent, whereas aquifers in fracture zones in igneous and crystalline rocks may have a very limited lateral extent. When searching for water using any geophysical method, including the Electro seismic method, the type of aquifer that may be present should be considered, both when planning a ground water survey and especially when considering drilling a well.

Click to learn more about aquifer types at USGS

• Confined—An aquifer overlain by one or more layers of impermeable rock or soil that restrict water to within the aquifer. The water is confined under pressure. Drilling a well into a confined aquifer releases that pressure and causes the water to rise in the well. These wells are sometimes called artesian wells.

• Unconfined—An aquifer that is not overlain by a layer of impermeable rock or soil. Water in a well will naturally stay at the level of the water table. As water is removed from the well, the water table at that place is lowered, causing the surrounding ground water to flow toward the well.

Whether you are on a fractured rock aquifer, an artesian aquifer, a confined aquifer, an unconfined aquifer or have no groundwater at all,  the benefits of a groundwater survey when planning a new well, far outweigh the costs of drilling a dry well.

Southwest Groundwater Surveyor
URL: http://findwaterfirst.com
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Phone: 800-394-6207

Southwest Groundwater Surveyors serve California, Arizona, Nevada, New Mexico, and Utah.

Ideal Conditions for a Groundwater Survey Prior to Well Drilling

    Having a reasonable expectation of finding well water prior to drilling a well is a great benefit for the prospective well owner.  Southwest Groundwater Surveyor uses the seismoelectric method for locating the optimal  well drilling location.

    Briefly, the  seismoelectric method, sometimes called electroseismic or Electro Kinetic Seismology (EKS) makes use of a phenomenon, known since the 1950’s, whereby an electrical signal is produced when a seismic wave encounters water within rock pores, such as is the case for an aquifer.  Although the basic Physics of the method has been understood for many years, and numerous field demonstrations have been completed showing the feasibility of the method, it was not until 1996, when a company called Groundflow Ltd. and later AqualocateLLC developed and patented very specific electronics and associated techniques required to measure and interpret the EKS signal, making the method more practical.  Whereby using these techniques, the EKS signal is recorded using a data recording geometry that significantly minimizes naturally occurring electrical noise.  Groundflow Ltd developed the instrumentation to both record this signal and to process the data.  Therefore allowing the existence of groundwater, (if present) to be inferred along with estimates of the depth and the yield of the aquifer.

   Accuracy of interpretation of groundwater data may often be increased if a local well is available where the aquifer depth, thickness and flow rate are known.  In this case a sounding can be conducted close to the well, which gives us a better velocity and acoustic attenuation model for the particular underlying rock matrix. 

   The ideal conditions for a groundwater survey are as follows...

1. Access to the desired test sites on the property by a 4 wheel drive pickup truck.
2. Survey sites must be at least 50 feet away from underground high voltage lines.
3. Surveyors must be able to penetrate the ground surface to a three foot depth.

For additional information;

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