Concerns were raised for British Waterways when six of their lagoons adjacent to the Long Sandall Lock Canal, holding 100,000 cubic metres of dredging sediment, were nearing capacity. The lagoons are vital for storing sediments, the removal and re-use of which is a major part of successful canal operation.
Our Environment team was brought in to determine whether the sediment could be reused as infill for canal bank stabilisation works. Existing waste guidelines classified dredgings as 'hazardous waste', assuming that the sediments were in a worst-case chemical form.
Our team challenged this interpretation and, working closely with environmental regulators, developed a testing strategy that correctly classified the canal dredgings. Detailed assessment was used to demonstrate that dioxins and hydrocarbons did not in fact exceed hazardous waste thresholds. Extensive modelling as part of a Human Health & Controlled Waters Risk Assessment was also conducted and found that the material was suitable for reuse.
The dredgings were subsequently classified as 'non-hazardous' in accordance with good environmental practice. This is helping to maintain the economic viability of the canal system by saving British Waterways around £150m in unnecessary disposal and new construction material costs.