Case Study

	Please click on images to enlarge
	Irish Bridge across diversion
	Start of river diversion
	Preliminary cut for diversion

The Avenue Coking Works
 
Remedial work was required on the Tar Lagoons at the Chesterfield Coking Plant to prevent them from collapsing into the River Rother. Because of the extremely toxic nature of the tar the site was registered as a COMAH site. All site works had to be undertaken in full BA and the site was ringed by monitors to warn of any contaminant escape.
 
Prior to any construction work the existing lagoon bunds were wired up with extensometers to allow real time monitoring during the construction work to warn of any critical movements in the bunds. The existing bunds were buttressed with an additional reinforced earth bund to prevent future collapse.
 
To provide additional environmental protection a section of the River Rother was diverted away from the coking works to ensure that the risk of any further contamination from the Tar Lagoons was removed. This work included the diversion of existing sewers and the construction of various culverted structures.
 
The river diversion was complicated by the presence of Water voles which meant that no works could occur which would disturb the vole's environment. The base of the river diversion was created using locally derived clays and a geosynthetic bentonite clay liner. The base of the river channel was protected with a 300mm layer of gravels.