Page 393 - Trenchless Technology Piping Installation and Inspection

Inspection and QA/QC for Trenchless Installation and Replacement Methods 343

6. Rig and mud circulation and recycling equipment: The rig size,
and mud system/recycling equipment capacity must match
the job size. A rig with inadequate torque and trust capability
will cause the installation to be more difficult, putting the
installation at risk. Similarly, an under capacity mud circula-
tion system, that is, inadequate tank or pump capacity, or
recycling system, can have the same consequences.
7. Installation: A successful installation must follow the planned
bore with as-built that approximates the planned path, main-
tains specified clearance from hazards and other utilities,
stays within easement, minimizes and deals with inadvertent
drilling nearby construction sites, as well as maintains integ-
rity of the road embankment and other nearby structures.
8. Record keeping: Tracking systems can provide electronic records
of the product pipe location. In the event that the tracking sys-
tem does not record installation information electronically,
accurate manual records must be maintained to verify location
and compare against the boreplan. Newer systems provide
planning software as well as recording of installation. Real-
time records must be kept in a driller log of pitch and depth of
each drill string, the drilling fluids used, and any special condi-
tions encountered in installation. This information provides a
record for verification of pipe location and drilling operations.
9. Fluid monitoring: Monitoring drilling fluid returns is also an
important QA/QC procedure. Generally, drilling fluid, which
carries soils from downhole, must exit the borehole at the entry
or exit end of the installation. Drilling fluid flow provides vis-
ual verification that the borehole is open and that the fluids
are not inadvertently escaping. Lost circulation may be an
indication that something is wrong. Field tests that measure
the drilling fluids viscosity and weight can help determine
the need to adjust drilling fluid mix and the rate at which a
product pipe can be safely installed. If the drilling fluid is
being recycled, the recycling equipment must be inspected
regularly to make sure that it is removing solids from the
drilling fluid. If the percent solids in the fluid become exces-
sive, adjustments in the system operation must be made to
avoid damaging equipment.
10. Bits and reamers safety: Changing bits and reamers can be a
potential safety hazard. Always use proper communications
procedures and equipment such as breakout wrenches when
changing bits and reamers.
11. Pipe products: HDD can be used to install a number of pipe
products. The most common are plastic pipes (HDPE and
PVC) and communications conduits, steel, and ductile iron.