Project

Remediation of a former gas works and industrial site

Contaminant

Hydrocarbons (coal tars), ‘blue billy’ and heavy metals

Challanges

Obtaining Regulatory sign off for the project whilst working along side the Main Construction programme.

Working alongside a canal and river on each side of the site.

Excavating a 36m diameter, 9m deep gasholder with water ingress at 7.5m below surface level.

Operating a contaminated site within a city centre.

Churngold Solution

A detailed risk assessment provided different contaminant levels that could be retained in identified contaminant zones in relation to the distance to the key receptor that was the adjacent river. Clean materials could be moved around, however contaminated soils deemed suitable for retention on site had to be retained within the zone it was found to prevent movement of wastes that would require a waste management license. Churngold also took on the risk of recovering a minimum of 20% of re-useable aggregate from the excavated soils. A total of 30,000m3 of soils were excavated and processed as part of the cut and fill exercise required on the site. Less than 500m3 of contaminated soils were removed from site.

Churngold also identified volumes of inert material for disposal off site thus allowing retention of suitable for use ‘contaminated’ soils on site that otherwise would have resulted in a more costly disposal route. The detailed audit trail of soil movements on site and the associated validation report provided by Churngold was critical in getting the site signed off by the Environmental Agency and thus secure the stakeholders funds for the projects completion.

Technologies employed

• Extensive recycling of hard materials and aggregates
• Reprofiling of 30,000m3 of excavated material
• Dewatering and treatment of water within the gas holder
• Insitu and ex-situ composite sampling to delineate and validate the site