Environmental Sampling Techniques - Fundamentals of Environmental Sampling and Analysis - page 78

A bladder pump consists of a stainless steel or Teflon housing that encloses a
Teflon bladder. It is operated using a compressed gas source (bottled gas or an air
compressor). Groundwater enters the bladder through a lower check valve, compressed
gas moves the water through an upper check valve and into a discharge line. A bladder
pump can be used to sample a depth of approximately 100 ft. It is recommended
for VOC sampling because it causes aminimal alteration of sample integrity. The pump
is somewhat difficult to decontaminate and should be dedicated to a well.
Not shown in Figure 4.4 are other pumps used for sampling or well
development. A submersible pump can be used for high flow rates (gals/min), but
it is hard to decontaminate. A suction pump is good for well development, when the
proposed well area has a lot of sediment. The disadvantage is that it is gasoline-
driven and the pump needs to be primed, meaning water needs to be added to the
well in order to do this. It is effective only to a depth of 20 ft. An air-lifter pump
operates by releasing compressed air. The air mixes with water in the well to reduce
the specific gravity of the water column and lift the water to the surface. It is
therefore used in well development rather than sampling.

Soil Sampling

Soil depth and whether or not each soil horizon is needed are the major factors to
consider in theproper selectionof soil sampling equipment. Scoops or trowels (Fig. 4.5)

(a) (b) (c) (d)

(e)

Driving shoe Sampler head

Split-barrel
Sampling tube

Ball check
valve

Vent

Figure 4.5 Common sampling tools used for soil: (a) Scoop or trowel, (b) Tube sampler, (c) Bucket
auger, (d) Hand auger, and (e) Standard split spoon sampler (U.S. Army Corps of Engineers, 2001)