Appendix A - HDD at CSXT Navassa Bridge & Under the Cape Fear River

HORIZONTAL DIRECTIONAL DRILL (HDD) AT CSXT NAVASSA BRIDGE & UNDER THE
CAPE FEAR RIVER, WILMINGTON, NC
HDD EXIT PIT ACCESS PATH EXPLANATION
Based on experience with similar horizontal directional drilling (HDD) projects, CSXT anticipates the
HDD contractor will require a 16' wide, temporary, timber -matted access path from the river's edge to the
exit pit drill pad (see Figure 1 from EC-14 below) on the east side of the river. The proposed 16' width of
the access path is necessitated by the equipment required to perform the work (see Figures 2 and 3 for
typical size of equipment used in HDD operations) and is considered the minimum practical width. The
HDD Contractor will access the east side of the river by barge to construct the timber -matted access path
from the riverbank to the exit pit area. Following completion of the access path, the HDD equipment and
materials will then be transported to the exit pit area from the barge via the access path.
Feasibility of Alternative Access Methods Considered: CSXT considered the following alternatives and
concluded that the above -described temporary access path is the only practical way to access the exit pit
at this location.
• Hi -Rail Alternative:
o It was determined that it would not be practical to transport HDD equipment and
materials to the site on the CSXT mainline via hi -rail equipment due to amount/size of
HDD drill rigs, pump truck, pipe racks, excavator and drilling materials. Specifically,
this was a concern since accessing the site from either direction would require crossing a
bridge with the oversized equipment. Furthermore, due to the variability of HDD work
schedules, there is a potential for interference with rail operations since this section of
track is only a single mainline (i.e. no alternatives for rail traffic).
o HDD contractors typically recycle the bentonite clay, used during drilling operations, by
vacuuming it from the exit pit and transporting it back to the entry pit throughout the
operation. They also re -use trailing rods (drill pipe that is typ. 20' long segments) and will
need to be able to transport these materials from the exit pit to the entry pit at various
times. The schedule for which bentonite and trailing rods must be transported from one
place to another are not known well in advance as it depends on how drilling operations
progress each day. Coordinating hi -rail transportation to transport materials back and
forth would be expected to cause delays for the HDD contractor, and possibly for freight
traffic.
Using Crane from Barge Alternative:
o Use of a barge -mounted crane to transfer equipment to the bore site was considered, but
determined to be infeasible due to the excessive pick radius required, as well as the
weight of the equipment (since it would be sitting on a barge). The crane's radius from a
barge to the exit pit area is over 150'resuting in the need for a crane so large that it could
not be mounted on a barge in this area.
Page l of 3

HORIZONTAL DIRECTIONAL DRILL (HDD) AT CSXT NAVASSA BRIDGE & UNDER THE
CAPE FEAR RIVER, WILMINGTON, NC
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FIGURE 1. View of Exit Pit Area
FIGURE 2. Typical HDD Exit Pit Equipment
Page 2 of 3

HORIZONTAL DIRECTIONAL DRILL (HDD) AT CSXT NAVASSA BRIDGE & UNDER THE
CAPE FEAR RIVER, WILMINGTON, NC
FIGURE 3. Typical HDD Entry Pit Area and Timber Matting
Page 3 of 3