5.6.5.1 Description 401. Cable joints would be used to connect together two separate drum lengths of cable to make a continuous cable.
402. The joint would be completed in a jointing pit, the excavation of which would form part of the trench excavation process during direct lay or require dedicated construction activity if pre-installed ducts are used. The jointing pit would be back- filled following the cable jointing and the land returned to pre-construction condition.
403. The base of the jointing pit must be made level and a concrete slab would be installed to form a working surface. The concrete slab would remain in place following completion of the joint. A jointing pit would measure approximately 10m x 3m and would be approximately 2.5m deep to the top of the level base surface. Once the jointing pit has been back-filled the cables would be approximately 1.2m below ground level.
404. The distance between jointing pits would be determined by a number of factors, including the length of cable on any given cable drum and any engineering constraints (such as prevention of tight bends in the route). Typical distances between jointing pits would be between 500 and 1,000m. For the smaller HDD crossings it is likely that a jointing pit would be required on at least one side of the crossing, and for the larger HDD crossings a jointing pit would be required at both sides.
405. It is likely access provision would be made at some of the joint locations for routine integrity testing. Access would take the form of a small kiosk as described previously.
406. Ideally jointing pits should be situated close to the field boundaries where possible to provide easy access during construction (in the case of the cable pulling option) and to provide access to inspection pit or kiosks and minimise visual impact and disruption of farming activities.
5.6.5.2 Methodology 407. The construction of a jointing pit typically requires the following:
Polyethylene plastic membrane between the ground and concrete floor;
A flat level reinforced concrete foundation and additional sump pit at a lower level to facilitate drainage and dewatering;
Preliminary Environmental Information May 2014
East Anglia THREE Offshore Windfarm
Chapter 5 Description of the Development Page 85
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