A shallow well, also called a dug well, is less than feet deep and constructed above the bedrock. Placement and drilling of these wells depends on the soil type — the best geology make-up sandy gravel. An excavator digs into the ground as deep as possible to ensure a high yield. A layer of crushed stone is laid at the bottom of the well and a 1- to 2-inch pipe, called a casing, is installed in the well.
The casing has a screen on the end which holds back the sand or gravel while allowing water to flow through. There are no state requirements concerning minimum well water quality or quantity for private domestic wells, but some municipalities have their regulations, especially when it comes to where you are allowed to dig new wells.
Check with your town offices for specific ordinances. This includes where the well is located, recent malfunctions, water quality tests and the date of installation. Shallow wells are less likely to experience naturally occurring contamination from radon or arsenic, but they are more susceptible to bacteria contamination. Shallow wells can also experience iron, manganese and taste and odor problems. Methemoglobin cannot carry oxygen; this leads to oxygen starvation and in extreme cases, suffocation.
Nitrite can also be converted to other compounds that have been known to cause cancer in laboratory animals. It is, therefore, assumed that these compounds could increase the risk of human cancer, although there is no direct evidence for this. For these reasons nitrate sampling and analysis is required at least once every 36 months.
Environmental Health Services Private wells, plumbing and onsite sewage systems Private wells Facts and applications About shallow wells.
About shallow wells. A shallow well is a hole which has been dug, bored, driven or drilled into the ground for the purpose of extracting water is a well. A well is considered to be shallow if it is less than 50 feet deep. The source of a well is an aquifer. An aquifer is an underground layer of permeable soil such as sand or gravel that contains water and allows the passage of water.
Aquifers are replenished as rainfall seeps down through the soil. Ground water travels through permeable soil on top of hard or impermeable layers. Shallow wells usually are only deep enough to intercept the uppermost or most easily reached perched water table. Types of wells. Water table wells Water table wells penetrate into aquifers in which the water is not confined by an overlying impermeable layer. The level at which the soil is saturated is the water table.
Pumping the well lowers the water table near it. These wells are particularly sensitive to seasonal changes and may dwindle during dry periods. Artesian wells Artesian wells penetrate into ground water having confining layers above and below the aquifer. Rainfall enters into the aquifer through permeable layers at high elevations causing the ground water to be under pressure at lower elevations.
Because of this pressure, the water level in the well is higher than the aquifer. A well that yields water by artesian pressure at the ground surface is a "flowing" artesian well. Protect the source of groundwater from becoming contaminated. A poorly protected well carries the following characteristics: Is located within feet of pollution sources, and is not sloped to divert surface water runoff away. Does not have a sanitary well seal. The annular space around the well casing is not properly sealed with cement grout or bentonite clay.
Does not have a pump house to protect the well-head, storage tank, and other equipment. Has a well pit to house the pumping equipment or to permit access to the top of the well.
The wellhead protection area is not under the control of the operator or purveyor. A properly protected well carries the following characteristics: Has no sources of pollution within a foot radius and is on high ground, sloped away in all directions from the well casing to divert surface water runoff.
Has an overlapping, tight-fitting cover or sanitary seal at the top of the casing or pipe sleeve. The annular space outside the well casing is sealed with cement grout or bentonite clay at least 2 inches thick to a minimum depth of 18 feet. Has a pump house to protect equipment, storage tank, and piping. Has a pitiless adapter instead of a well pit. Has a well-head protection area under the control of the operator or protective covenants.
How wells are constructed. Dug wells In the past, holes or pits were dug by hand or machines into the ground to tap the water table. Getting water from the well to the house.
Two types of storage facilities commonly used are: A pressurized storage tank - protects the pump, so the pump does not have to turn on every time someone uses the water. Compressed air in the tank maintains water pressure throughout the distribution system. Pressure can be kept between desired limits by using electrical switches. Typically, only 10 to 40 percent of pressure tank volume is usable for storage. For this reason, pressure tanks are only designed for peak water demands.
A pipe and a pump are used to pull water out of the ground, and a screen filters out unwanted particles that could clog the pipe. Wells come in different shapes and sizes, depending on the type of material the well is drilled into and how much water is being pumped out. More than 42 million people in the United States use individual or private wells to supply water for their families.
Bored or shallow wells are usually bored into an unconfined water source, generally found at depths of feet or less. Consolidated or rock wells are drilled into a formation consisting entirely of a natural rock formation that contains no soil and does not collapse. Their average depth is about feet. Unconsolidated or sand wells are drilled into a formation consisting of soil, sand, gravel or clay material that collapses upon itself.
All private well construction is based on establishing the right location for the well, sizing the system correctly and choosing the proper construction techniques. Only professional water well contractors should install wells. They are familiar with the hydrology in an area and all local codes and regulations. Proper well construction is key to operating and maintaining a well. Casing is used to maintain an open access in the earth while not allowing any entrance or leakage into the well from the surrounding formations.
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