JSM installed two No 33kV 630cu XLPe circuits between Brockworth and Castle Meads substations, replacing the existing fluid filled circuits. The trench cross section consisted of 2 x 210mm electric ducts 450mm separation and 2 x 96.5mm Surf Telecom ducts which were installed using the open cut excavation method with one HDD across the A417/ A40 roundabout. The overall cable route length was 10Km, which was constructed on major public roads, densely populated residential roads, park land and unmade ground.
This route offered a number of challenges which included 19 SED’s, excavating over leach drains, excavating over/working in the vicinity of a government oil pipeline and restrictions on a number of roads enforced by the local authority. The overall project delivery hinged on three sections of the route, Castle Meads substation, Archdeacon Meadow and Cheltenham Road. The execution and timing of the construction work in these areas was vital in the delivery of the project within the timescales.
Castle Meads substation is built on a flood plain surrounded with flood defence walls. Our cable route had to be constructed under the flood defence walls and the timing of these works had to be planned around the weather and high tides.
Cheltenham Rd was the longest road on the route and had the most restrictions on it. This road is a traffic sensitive road and it is also a main route for an executive coach running commuters between Cheltenham and Gloucester. Along this route we had to maintain restricted site lengths, manually operate the traffic lights to accommodate the coaches so that they were no delays on their time table. This section of work was closely monitored by the highway authority and the coach inspectors. These works were completed on programme with little disruption.
We reduced the number of joint bays along the route which offered a financial saving to the client. We also installed the cable within 2 x 210mm duct instead of the original proposed design of 6 No 160mm duct which again was another saving. As the cable lengths were so long each cable drum weighed 11 tonne and as we installed three cables within the duct, we were pulling three drums at any one time which was total of 33 tonne of cable been installed on each pull.