Well-Point Systems

There are three common methods for groundwater collection using pumping systems a well point system, a gravity drain system, and in combination with injection wells. 

A well point system consists of several individual well points spaced at 0.6 m to 1.8 m intervals along a specified alignment. A well point is a well screen (length 0.5 to 1.0 m) with a conical steel drive point at bottom. Individual well points are attached to a riser pipe (diameter 2.5 to 7.5 cm) and connected to a header pipe (diameter 15 to 20 cm). At the midpoint, the header pipe is connected to a centrifugal pump. As yield at different well points may vary, a valve at the top of each riser pipe is used to control the drawdown so that the screen bottom is exposed. The pump provides 6 to 7.5 m of suction, but friction losses reduce the effective suction to 4.5 to 5.4 m. 

The well point system is the most economical method of groundwater collection where the water table is less than 3 m and the contaminant is less 9 m below the surface. 

Where LNAPL is situated at shallow depth (<20 ft or 6 m), in moderate to high permeability soil (> 10 s cm/s), a well-point system may be the appropriate recovery technology. The use of well points for LNAPL recovery is similar to construction dewatering. A major advantage to this type of system is that it is possible to lower... 

The well-point system is used to create a flow barrier, as opposed to an open trench collection system, for three primary reasons ... 

The design of a well-point system for remediation is similar to that of a dewatering system, with a few notable exceptions relating to the nature of the product to be recovered. Prior to the design effort, a hydrogeologic investigation is necessary to assess ... 

Vacuum-Enhanced Suction-Lift Well-Point System... 

FIGURE 7.10 Two layouts for well-point system using eductors. 

Vacuum-enhanced suction-lift well-point system ... 

VACUUM-ENHANCED SUCTION-LIFT WELL-POINT SYSTEM... 

Figure 4.5 Approximate data for well point system design.

Flow of water through large pervious masses can be controlled on a temporary basis by pumping and by well-point systems, and on a temporary or permanent basis by slurry walls and grout curtains. 

Well point is a long thin tube which is installed vertically into the ground and through which groundwater is pumped. A well point system is a system of well points situated around the excavation area and used to pump out groundwater and reduce the flooding risk in the excavation trench. 

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