Environmental Engineering Reference
In-Depth Information
Atmospheric
pressure
Header
Silty clay
Sheeted
trench
for
Water table
Sewer
pipe
Seal
Sand
Vacuum
Silt
FIGURE 8.44
Installation of a vacuum wellpoint to reduce pore
pressures in a silt stratum to provide a firm trench
bottom for sewer pipe foundations. Separate system is
used for sand stratum.
Wellpoint in coarse
sand filter
Pressure line 100
−
150 lb/in.
2
(7
−
10.5 kg
f
/cm
2
)
Return line 10
−
15 lb/in.
2
(0.7
1
1
/
2
-in. (38-mm)
swing
1.05 kg
f
/cm
2
)
100 lb/in.
2
(7 kg
f
/cm
2
)
−
1-in
(25 mm)
swing
A
Return
pressure
15 lb/in.
2
1-in (25 mm)
riser pipe
1
1
/
2
-in. (38 mm)
riser pipe
1
1
/
2
-in. (38 mm)
Wellpoint dewatering
Corp eductor
FIGURE 8.45
Operation of Griffin jet-inductor
wellpoint. (From Tschebotarioff, G.P.,
Foundations Retaining and Earth
Structures,
1973.)
1
1
/
2
-in. (38 mm)
Griffin wellpoint
