Sustainable Water Management - Sustainable Practices in Geoenvironmental Engineering - page 85

Well with screen at
bottom

Grout seal Tubing

Hollow
tube

Backfill

Sampling
port

Filter
sand

Single hole multilevel
monitoring and
sampling wells

Single tube multilevel
monitoring well

Nest of monitoring and
sampling wells

FIGURE 3.7
Some typical groundwater monitoring and sampling wells. (From Yong, R.N. and Mulligan, C.N., Natural
Attenuation of Contaminants in Soils , CRC Press, Boca Raton, 310 pp., 2004.)

shows a single tube system with monitoring portholes located at the desired depths. With
present technological capabilities, monitoring wells and the manner of operation have
reached levels of sophistication where downhole sample analysis of groundwater can be
performed without the need for recovery of water samples.
Site characterization monitoring is necessary to provide information on the hydro-
geology of the site. It is necessary to properly characterize subsurface low to fully
delineate or anticipate the transport direction and extent of the contaminant plume.
Determination of the direction and magnitude of groundwater low is most impor-
tant. Obviously this means a judicious distribution of monitoring wells up- and down-
gradient. Proper locating of monitoring wells and analysis of the results should provide
one with knowledge of the source of the contaminants and the characteristics of the
contaminant plume.
Veriication monitoring requires placement of monitoring wells and soil sampling
devices within the heart of the contaminant plume and also at positions beyond the plume.
Figures 3.6 and 3.8 show the vertical and plane views of how the wells and sampling
stations might be distributed. It is a truism to state that the more monitoring and sam-
pling devices there are, the better one is able to properly characterize the nature of the
contaminant plume, assuming that the monitoring wells and sampling devices are prop-
erly located. The monitoring wells and sampling devices placed outside the contaminant
plume, shown in Figure 3.6, will also serve as monitoring wells and sampling devices for
long-term conformance assessment.
The tests required of samples retrieved from monitoring wells are designed to determine
the nature of the contaminants in the pore or groundwater. These will inform one about