The University of Sussex - District Heating Reconfiguration & Extension

Normal excavations for district heating pipework range from 1-2m in depth and width, however due to the undulating land and steep gradients that make up the South Downs, we needed to excavate to 5m in places. Therefore, our initial scope of work doubled with an average trench depth of 3.5m and 8m wide.

To accommodate the changes, we amended our methodology to ensure we would complete the work on time, and so brought in two civils teams to work in sequence while excavating the trench. The first team dug to 4m and the next team used a trenching excavator to accurately dig the final 1m for the pipe to be laid. Additionally, to safely support the 5m trench, we battened the excavation sides back to 45°  leaving the trench 11m wide in some places.

We installed 8-inch series 2 Logstor pipes with an outer casing of 355mm along the 700m trench. When the pipe was laid, our teams of welders and band-muffers worked together to seamlessly join the network and were commended by our client for the high-class quality of their installation during the difficult winter months.

We came across some service clashes on Boiler House Hill and innovatively avoided them by bending some of the pipework in position using pneumatic air bags. To do this, we used a system with up to 80 tonnes of pressure with the added advantage of not damaging the pipework as the airbags are soft. Our operatives were not at any risk as they did not need to be in contact with the pipe while the bags were inflating and this technique meant that we did not need to re-route the network to avoid clashes.

Finally, we were sensitive towards pedestrians on campus and the considerate measures that the university have taken to preserve the countryside environment. We devised a dynamic pedestrian access plan with several routes, which could be opened and closed to maximise flexibility, and always maintained access . Additionally, we communicated with other contractors and rerouted part of the network to avoid disturbing the local wildlife conservation areas, which are home to newts and badgers.