Environmental Engineering Reference
In-Depth Information
Slotted
screen
Flexible
PVC hose
Hollow drill
rod
(a)
(b)
Pump
Groundwater
storage
container
Pump
PVC hose
PVC hose
Groundwater
being pumped
Drill rod
(c)
(d)
(e)
FIGURE 4.21
(a) Stainless steel well screen; (b) Hollow drill rod and PVC hose; (c) Pumping groundwater; (d) Pumping
groundwater; (e) Groundwater sample in an appropriate 40 mL glass container. (Photos by Daniel T. Rogers.)
Groundwater samples are typically analyzed for specific chemical compounds having
detection limits in the microgram per liter (μg/L) or ppb range. These detection limits
mandate a representative sample not only because of these low detection limits—cleanup
standards are also very low for certain chemical compounds.
Monitoring wells are typically constructed of PVC, but may also be constructed of stain-
less steel (ss), Teflon, or steel. Figure 4.22 has a construction diagram of a typical monitor-
ing well.
The casing in a monitoring well is the hollow tube placed inside the borehole and pro-
vides access to the subsurface. The screen at the bottom of the well allows water to seep
into the well from the aquifer. Figure 4.23 shows the slots in the PVC screen that permit
groundwater to enter the well casing. The slits have a very small diameter so the water
enters the well but not the filter pack around the outside of the well screen. A filter pack is
placed around the well screen and serves to prevent any fine-grain sediment in the aquifer
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