Drilling of New Wells
Water wells are a mystery to many people, even though
their own homes are supplied by a residential well. If you are in need
of a well, whether it be for new home construction or to replace your
existing system, you deserve the best system you can buy. To accomplish
this you should understand the basics of well and pumping system
designs.
Screened wells and Open-hole wells are the two most prevalent well
designs in East Central Minnesota.
Screened wells provide water from sand and gravel aquifers of the
"glacial till" - the upper geologic deposits left by the ice ages. A
borehole is drilled until the desired water bearing sand or gravel
formation is penetrated. A cylindrical screen is attached to the bottom
of well casing and installed in the formation. Water then passes through
the screen and enters the well. The productivity of a screened well is
dependent on the ability of the formation to transmit water and the
length, diameter, and slot size of the screen.
Open-hole wells are finished in sedimentary bedrock such as sandstone and limestone. These formations are porous and fractured and allow water to pass through them. A borehole is drilled to the bedrock, and casing is installed and seated in the rock. A smaller hole is then drilled past the end of the casing to create an "open hole" in the bedrock. The open hole provides a conduit for the water flow into the well casing. Productivity of an open hole well is determined by the formation's ability to transmit water, and the volume of the open hole.
Once the well is completed a pump can be chosen.
Variables which are considered to determine the proper pump size
include: the static water level and specific capacity of the well, the
well size, flow requirements, pressure requirements, and size and length
of water pipes.
In an average household, 10 gallons per minute (gpm) of water at 40/60
psi is adequate for day-to-day use and 15 gpm is preferable. If any
extraordinary demands exist such as lawn irrigation, geothermal systems,
etc., it is important to size the pump appropriately to avoid an
undersupply to the house.
The pressure tank is a reservoir, which allows small amounts of water to
be consumed without excessive cycling of the pump. Submersible pump
motors are designed for continuous use and should operate for 1 minute
or longer during each cycle. The tank, therefore, should be large enough
to accommodate the flow rate of the pump. However, new "constant
pressure" technology is now available which drastically reduces the
required tank size. The tank is usually installed in the basement, but
other options are available.
BEFORE YOU BUILD
for several reasons, you will want to hire a well contractor
as soon as you finalize your building plans. In many developing areas,
contractors are experiencing backlogs of two months or longer.
Therefore, it is important to hire someone promptly to avoid delays in
your construction schedule. Also, determining the well location and
installation of water and power lines should be performed at the onset
of construction to achieve the best results.
Click here for information on how you can assist in protecting your well
15688 Jarvis St. NW - Elk River, MN 55330
Phone: (763) 427-6100 Fax: (763) 427-0533
E-Mail: bob@ehrenner.com