Introduction

The site is located on the University of Warwick campus and is bound by Lord Bhattacharyya Way, Library Road, and Gibbet Hill Road. The primary works area is associated with the phase 1 new build, which forms part of the later main contract and includes the construction of the new building on the site of the existing car park to the north of the site.

Project brief

To divert and commission services to accommodate a new building for the University to include the following:

• 4 x high voltage rings being fed from a National Grid Primary Substation. This included taking control of the private network and avoiding loss of supply to the numerous sub stations on the HV network feeding critical building across the campus

• 2 x 500mm district heating pipes which required minimum interruption

• 1 x helium recovery main

• Essential IT network which links to other facilities nationwide

• Low pressure 250mm gas main which was uncharted

Challenges

• Numerous unknown services which were constructed in many different methods

• New access to existing sub stations

• High level of footfall around the works area

• Numerous existing HV supplies to be kept in commission

• Coordination of the transfer of network supplies with several stake holders

How we overcame the challenges
During excavation we found numerous unchartered services, many of which were backfilled in concrete or installed in service troughs. Due to many of these existing live supplies being buried in concrete, we were unable to excavate under these supplies using normal methods. Our solution was to construct timber headings, five in total, to install diverted supplies under the structures installing temporary works either side of the obstructions and tunnelling underneath. Our Doocey Way of tracing mapped and unmapped service supplies had a positive effect using the Genny and CAT locating equipment with our skilled operatives with the result of no interruptions to supplies and no existing service damages.

To install new HV network rings it was required we gain new access into existing sub stations. To complete these it was required to remove existing switching equipment with the sub stations and protect the equipment that was left connected and live. We employed a specialist contractor to successfully remove the switching equipment and reinstate when complete an constructed a scaffold system to enable the placing of protective sheeting for the remainder of the equipment in use. Once the sub stations were prepared we excavated trenches within the sub stations and installed a new trough to accommodate the new HV cables. All works were completed without interruption to the existing electric network.

Naturally the University has an extremely high level of pedestrian activity which needed to be managed. To ensure the work areas were secure, we installed any specialist protection before or after the peak periods avoiding customer interface, we used secure fencing for busy areas, and worked nights in some cases not to interrupt vital deliveries to the University. We gave pedestrians alternative routes where possible and made design changes to suit. All temporary works areas were restricted and controlled to avoid access.

The energisation of the new network was vitally important to the success of the project, we designed a switching plan along with the University stakeholders to avoid any outages to existing supplies. We coordinated National Grid Electricity Distribution to install new breakers from their primary substation which gave the facility to install an extra ring to the diverted cables. This successful method removed the risk of the existing network being interrupted and experience no loss of supply.

The coordination of transferring the diverted supplies was important to the University for IT, district heating and gas, diverted supply interruptions were kept to an absolute minimum with careful and coordinated planning with several stakeholders of the University. Regular planning meetings and weekly progress updates were vital to the success along with the increase and introduction to our own specialist teams. All supplies were transferred to the diverted systems with either none or minimal disruption agreed in advance with the relevant stakeholders.