Page 151 - Water and wastewater engineering

4-6 WATER AND WASTEWATER ENGINEERING

Well head
(includes pump motor, discharge
head, and base plate)

Air-line
Discharge pipe gauge

Grout seal

Casing (note: an
outer casing may Overburden
also be used)
Overburden
Static water level
Column
and
shaft assembly

Drive shoe

Fractured
bedrock

Vertical turbine
pump bowl assembly
and intake
Open borehole
construction

(b)
FIGURE 4-1 (Continued)
( b ) Typical construction components of an open-borehole well in a bedrock aquifer.

Casing. The purpose of the casing is two-fold. It provides a means of maintaining the bore
opening by keeping loose and unstable soil from falling in. In addition, it is a key feature in pro-
tecting the well from contamination.
Steel pipe is commonly used for the casing. There are several types of pipe available: drive
pipe, line pipe, reamed and drifted pipe, standard pipe, and water well casing. Electric-resistance–
welded and seamless “line pipe” is preferred (Johnson, 1975). The most commonly accepted
specifications for water well casing are those prepared by: