Page 385 - Trenchless Technology Piping Installation and Inspection

Inspection and QA/QC for Trenchless Installation and Replacement Methods 335

Lubrication Fluids
1. Lubrication fluids, consisting of a mixture of water and
bentonite or bentonite/polymer, must be used in the annular
space between the casing being installed and the native soil.
This is done primarily to reduce friction on the casing. Lubri-
cation may also be used inside the casing pipe to facilitate
spoil removal.
2. Lubrication fluids are specifically recommended for this
method regardless of the soil conditions.
3. Grease or hydrocarbons are not allowed for use as lubrication.

Pipe Locating and Tracking
Commonly, a waterlevel system or other approved method is used to
monitor grade. A sonar transmitter or other approved method can be
used for monitoring alignment.
Figure 8.18 suggests a checklist for inspection of horizontal auger-
boring operations.

8.5 Pipe Ramming

8.5.1 Introduction
Pipe ramming is defined as a trenchless installation of steel casing
pipes under roads and railroad tracks. A ramming tool attached to
the rear of a steel pipe drives the pipe into the ground with repeated
percussive blows. For casing pipe diameters less than 8 in., the pipe
is installed closed face and soil is compacted around the pipe. For
casing pipe diameters more than 8 in., the pipe is installed open face
to allow the soil to enter the pipe during the installation (Figs. 8.19
and 8.20). The spoils inside the pipe can be removed after the instal-
lation by means of auger, compressed air, and/or water jetting. In
larger diameters (e.g., more than 100 in.), a small backhoe or bobcat
can be used for mechanical spoil removal.
Pipe ramming typically requires excavation of two pits. Before
ramming, both the pipe and the ramming tool are placed into the
insertion pit and lined up in the desired direction. Alternatively, the
ramming can be launched without an insertion pit, if the operation is
started in the slope of an embankment.
The roadbed influence area is defined as the subsurface area
located under the road and shoulder surface, between each shoul-
der point or back of curb, and continues transversely outward
and downward from each shoulder point or back of curb on a 1 on
1 slope.