Review of Cabling Techniques and Environmental Effects Applicable

Cable types and installation techniques
Fronds are popular with environmental organisations as there is a perception
that the indigenous substrate is being reinstated. However, experience has
shown that situations such as storms, which create high energy situations on the
seabed, have resulted in deposited materials around the fronds being stripped
out.
The installation procedure for the frond mattresses would be identical to that
explained above for concrete mattresses.
Uraduct
Uraduct is manufactured using high performance polyurethane elastomer. The
system comprises two cylindrical half shells which overlap and interlock to
form close fitting protection around the core product such as cable, umbilical
or flexible/rigid flowline. For ease of handling, the half shells are manufactured
in lengths of up to 2.0 metres with flexing characteristics to suit the required
minimum bend radius of the product or ancillary shipboard lay equipment.
The half shells are secured in place using corrosion resistant banding located
in recessed grooves to ensure a smooth external profile. A range of sizes is
available to support product outside diameters ranging from 15mm to 450mm
and beyond.
Uraduct comes in varying sizes and stiffnesses to resist different levels of impact
and is of particular use at cable crossing points or in areas close to structures, such
as offshore wind turbine support structures or offshore oil and gas installations,
where the risk from dropped objects is high. Uraduct is not commonly used
along longer sections of cable which has been inadvertently surface laid on the
seabed as it does not offer any further protection from trawling gear or anchors
and only increases the target size.
Articulated metal shell connectors
Articulated metal shell connectors are typically used to provide cable sections
with added mass and abrasion resistance in high energy environments such as
a cable shore landings, which pass over rock outcrops and where other forms
of cable burial are not possible. The articulated sections would be applied by
surface divers in half sections which are then locked or bolted together to form
a continuous pipe section.
Directional drilling
Directional drilling is employed by cable installation contractors when the
topography of a landfall site makes it difficult to achieve a conventional landfall
by trenching, or where there are environmental interest features that need to
be avoided such as saltmarsh or chalk cliff. Directional drilling provides a very
useful alternative, as it allows the cable installation to bypass the critical areas
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