Other Preparations
q
Remove dust caps from piezometer tips before installation.
q
Piezometers are sometimes placed in sand-filled canvas bags.
The bag centralizes the piezometer in borehole and acts as a sand
filter. Additional sand should be tremied around bag before ben-
tonite seal is placed.
Backfilling the Borehole
q
A bentonite seal must be placed above the piezometer tip. The
seal isolates pore-water pressure at the tip, and prevents grout
from displacing the sand around the piezometer and blocking the
entry of water. Be sure to supply enough water and allow enough
time for sufficient hydration (swelling) of bentonite chips or pel-
lets. Follow instructions supplied by manufacturer of bentonite.
q
Remainder of borehole is backfilled with bentonite or benton-
ite-cement grout to prevent unwanted migration of water through
borehole. Strength of grout should match strength of surrounding
ground as closely as possible.
q
If drill casing is used to hold borehole open, it must be pulled out
as sand is tremied around piezometer.
q
Drill casing must also be pulled slightly ahead of settling benton-
ite pellets or chips.
q
Installation is not complete until it is tested and initial readings have
been taken. Because ground and pore-water are disturbed during
installation, it is necessary to take series of readings to determine
when ground has “recovered” and repeatable readings are obtainable.
In impermeable soils this can take several weeks.
Piezometers
3-21
Rembco Geotechnical Contractors specializes in
slope stabilization,
soil nail wall,
foundation repair
and support,
grouting,
shoring,
micropile
construction,
rock drilling, and we remediate
sinkholes. We use a
problem-solving approach in the geotechnical portions of buildings, bridges, water plants, sewage plants, tunnels,
installing caisson bottom, and roads. We are experienced in these applications:
micro piles,
sinkhole repair,
permeation and
pressure
grouting,
soil nails,
cement grouting,
chemical grouting,
micropiles,
compaction grouting, and
rock anchors.
Rembco techniques apply when adding new structures: especially
rock anchor,
microfine cement,
soil nailing, and
micropile
installations for foundation support. Our specialties are
soil nails,
rock anchor,
chemical and
compaction grouting,
mini piles,
sinkhole repair,
micropiles, and
soil nailing.
