Our Role / Scope / Description of Works
DSM was engaged as Principal Contractor for the demolition and ground remediation of former Stevenson Dye Works, Derbyshire.
The site was a former laundry, part demolished to slab level, that extended to approximately eight hectares on steeply sloping ground down to the River Amber.
Our works involved the removal of all asbestos containing materials, the demolition of the structures on site and the removal of all slabs and foundations including retaining walls up to five metres in height.
The site was then re-profiled to allow later development for traditional residential units including the formation of a flood plane adjacent to the river. This re-profiling included a heavily wooded area above the site requiring trees to be felled and roots removed to allow for a cut of up to four metres deep. The soils on site were appraised and either taken off site as hazardous waste, treated on site under a mobile plant deployment or moved and placed at depth on the site in approved locations. Two plumes of shallow groundwater impacted with hydrocarbons and chlorinated solvents were also present. These were treated by excavating out the soils in the areas and pumping the water to foul sewer after on site treatment to remove the contamination. Suitable soils were replaced after the excavations’ base and sides were treated with reagents to accelerate the degradation of contamination in the groundwater when it re-established itself from the surrounding site.
The site had many restraints the most significant being:
A cast iron 29 inch high pressure water main crossing the centre of the site both below and above ground including a low height bridge. A five metre stand-off had to be maintained and plant could only cross the pipe at an installed structural crossing point.
An underground 11kV cable crossed the site most of which was in an area of cut.
The existing river bank had to be removed and a reduced level flood plane created along the length of the river. These works necessitated a permit being obtained from the Environment Agency.
An in-filled length of the Cromford Canal crosses the site along which plant movements were severely restricted. In conjunction with an appointed archaeologist investigations had to be carried out to discover what physical remnants remained below ground.
A permit to fell had to be obtained for the trees and the works carefully programmed to avoid the bird nesting season and for two buildings bat licences also had to be obtained.
Prior to contract award agreement had been reached with the Environment Agency to treat the groundwater in-situ by injecting in reagents to create both anaerobic and aerobic conditions. We obtained agreement for the more robust solution described as it gave more certainty of treatment and overcame the problem of preferential pathways.
To remove the AIB lining to a very large portal frame building in the timescale required by the bat license two very large enclosures were built using DSM’s tensioned wire system with enclosure sheeting being supported on steel wires fixed from the roof purlins to anchors installed in the concrete slab.