Water Well Maintenance and Rehabilitation
The purpose of the study to obtained water well screens opening size and gravel packs size, and to access within the groundwater inter through the aquifer to the well screen and prevent running sand from entering the well. The use of properly designed screen and gravels are important and this paper is an important reference for the design of groundwater wells. In this study, the purpose of the circle method is to design water well and the benefits of sand control. The determination of screen slot size and its variation in the opening is often a major aim of hydrogeological studies. However, measurement of hydraulic conductivity (K) at a high spatial resolution in sedimentary aquifers is a challenge. One commonly used approach is to estimate slot size from grain size analysis. The objectives of this study are to compare between curve of grain size analysis, bar graph and circle method used applied different formulas for the determination of slot size from grain-size data and to evaluate how well this method predicts slot size and gravel pack. Correlation between the mechanical analysis curve, bar graph and the circle methods were found for the used applied different formulas. Based on circle results, the applied circle formulas appear to be suitable for an initial assessment of aquifer properties. However, considering the difference in calculated aquifer parameter values, results are smaller significantly and reliable for the high analysis of aquifer materials.
The well screen is the component of a well which provides an opening through which water enters the well casing from the aquifer, as well as stabilizing the material in the “near-well zone” and preventing it from entering the well. Screens may be constructed with a variety of different materials and designs, as appropriate to the design of the well and its aquifers. Typical types of screen are:
Horizontal bridge slot screen, a pipe-based well screen with punch-formed downward facing louver-shaped openings.
Continuous wire wrap screens, manufactured by wrapping shaped wire around an internal array of rods.
Bridge slot screens, produced by rolling and welding perforated steel plates or sheets.
Machine-slotted (milled) screens, manufactured by milling casing with axially oriented precision cutters.
Well casing perforated in place with a mills knife or a hydraulic perforator lowered down the cased borehole.
Different wedge wire screen may by evaluated for a particular well design based on the material, size of perforations, percent of open area, cost, susceptibility to corrosion, and collapse strength. A properly designed screen allows sand-free water to flow into the well with a minimum drawdown.
As a water well ages, the rate at which water may be pumped (commonly referred to as the well yield, flow or performance) tends to decrease, especially in wells that were not properly developed when first drilled. This fact sheet briefly describes common well problems and discusses prevention and rehabilitation measures.
Water Well Maintenance
Water wells require regular maintenance to ensure adequate water flow and continued drinking water safety. To ensure water quality, well water should be tested annually for total coliform bacteria and E. coli bacteria by a state accredited testing laboratory.
Every three years, additional testing is recommended for pH and total dissolved solids as well as tests related to land uses occurring or expected to occur within sight of the well. Additionally, if there are obvious stains, tastes, or odors in water, seek testing that will help identify the source of these symptoms.
Water wells should also be inspected annually for obvious signs of damage or contamination. Be sure the area within 100 feet around the continuous slot screen is clear of debris or items that might pollute the water supply.
The type of acid to be used, its form (liquid, granular, pelletized), the procedures used to introduce and agitate the acid solution, and the severity of incrustation all play a part in determining the success of acid treatment. It is common for acid-treated older wells to completely recover or even exceed the original well yield assuming any material dislodged by the acid is removed from the pre-packed well screen.
