Page 410 - Trenchless Technology Piping Installation and Inspection

360 Cha pte r Ei g h t

6. Whenever a significant amount of unexpected groundwater
enters an access pit, and a catastrophic pit failure is immi-
nent, the pit must be backfilled immediately, until the ground-
water level is at least 2 ft below the bottom of the pipe.

8.11 Boring/Ramming/Bursting Failure

1. If anything prevents completion of this operation, the remain-
der of the pipe must be constructed by methods approved by
the engineer/inspector.
2. Abandonment of any component of the installation must
only be allowed as approved by the engineer/inspector.
3. If an obstruction is encountered which prevents completion
of the installation, the pipe must remain in place, taken out of
service, and immediately filled with flowable fill.
4. The cost associated with encountering obstructions such as
boulders shall be paid for as extra work.

8.12 Contamination
When an area of contaminated ground is encountered, all operations
must stop immediately, and must not proceed until approved by the
engineer/inspector. Any slurry must be tested for contamination and
disposed of in a manner, which meets local, state, and/or federal
requirements.

8.13 Bulkhead
In horizontal auger-boring and pipe-ramming operations, casing
ends must be enclosed or bulkheaded with a commercial grade con-
crete, or approved alternate to seal the ends to prevent water leakage
or earth infiltration. The concrete must extend longitudinally into the
pipe end opening to create a minimum 1-ft-thick bulkhead barrier, or
as required by permit. Engineer/inspector may allow rubber bulk-
heads in special situations.

8.14 Work-Site Restoration
1. Access pits and excavations must be backfilled with suitable
material, and in a method approved by the engineer/inspector.
The shafts must be backfilled and sealed upon completion of
the microtunneling. The shaft and supports must be removed
to 10 ft below the original ground surface. The disturbed