SUMMARY OF WORKS AND SERVICES UNDERTAKEN

• Site preparation and earth works
• Piling mat construction and 74 precast concrete driven piles
• Reinforced concrete slab for the main generator housing; transformer bund; radiator bund; switch room and control room
• Drainage works
• External surfacing
• Palisade and Paladin fencing
• Provision of the control room, workshop and associated steel support frames

Knights Brown was contracted to construct a 20MW Short Term Operating Facility (STOR) in Birkenhead, Merseyside. Our client is a global provider of power generation systems, components and services in standby power, distributed power generation, as well as auxiliary power in mobile applications to meet the needs of a diversified customer base.

At the start of the project a reinforced concrete slab covered the site, which was removed as part of the site clearance. As a cost saving to the client, we proposed the existing concrete was crushed to use as hardcore material for the crane hardstanding and external surfacing. This idea was accepted and as a result it reduced the quantity of stone imported to site by 1,000T. The use of pile caps in the slab design also produced a cost saving as it resulted in the slab thickness being reduced by 175mm and thus saving a total of 195m3 of concrete.

The site was on the edge of Gillbrook Basin, West Float which is a dock off the river Mersey. The main genset slab which was piled was constructed 5m off the dock wall edge. Due to the proximity of the dock wall the vibrations from the precast concrete piling operation was a cause for concern. It was resolved by constant monitoring of the dock wall throughout the piling. This was carried out by vibration monitoring equipment located at stations along the dock wall that were checked regularly to insure vibration levels did not exceed the safe limits.

Due to the location of the site and the historical use of the land there was a high water table and contaminated ground. This restricted the depth of installing drainage on site as the dock sensitivities regarding pumping of water on site. Any waste water had to be removed offsite via vacuum tankers. The drainage requirement included for an oil separator tank but this was proved unfeasible to install as the excavation required would exceed 4m and require extensive temporary works and contamination remediation works.

We proposed a biomat and perma-channel system, which acts as an oil separator system without the requirement for extensive excavations