Page 398 - Trenchless Technology Piping Installation and Inspection

348 Cha pte r Ei g h t

3. Drilling fluids must not enter the streets, manholes, sanitary
and storm sewers, and other drainage systems, including
streams and rivers.
4. Any damage to any DOT highway or non-highway facility
caused by escaping drilling fluid, or the directional drilling
operation, must be immediately restored by the contractor.

Pipe Locating and Tracking
1. During construction, continuous monitoring and plotting of
pilot drill progress must be undertaken to ensure compliance
with the proposed installation alignment and allow for appro-
priate course corrections to be undertaken. Monitoring must
be accomplished by manual plotting based on location and
depth readings provided by the locating/tracking system or
by computer generated bore logs, which map the bore path
based on information provided by the locating/tracking sys-
tem. Readings or plot points must be undertaken on every
drill rod.
2. Pipe installed by the HDD method must be located in plan as
shown on the drawings, and must be no lower than shown
on the drawings unless otherwise approved. The contractor
must plot the actual horizontal and vertical alignment of the
pilot bore at intervals not exceeding 30 ft. This “as-built”
plan and profile must be updated as the pilot bore is
advanced. The contractor must at all times provide and
maintain instrumentation that will accurately locate the pilot
hole and measure drilling fluid flow and pressure. The con-
tractor must grant the engineer/inspector access to all data
and readout pertaining to the position of the bore head, the
fluid pressures, and flows.
Figure 8.23 suggests a checklist for inspection of horizontal direc-
tional drilling operations.

8.7 Pipe Replacement

8.7.1 Introduction
Trenchless pipe-replacement methods are defined as the renewal of
existing pipelines by the simultaneous insertion of new pipe within
the path of the existing pipe by the use of using a static pull, hydrau-
lic expansion, or pneumatic bursting device. The existing pipe is frac-
tured, and pushed into the surrounding soil or removed. At the same
time, a new pipe is either pulled or pushed in the annulus left by the
expanding operation. The new pipe size cannot significantly exceed