Land Contamination: Technical Guidance on Special Sites: Acid Tar ...

6.4 ValidationThe principles of validation are the same for the remediation of acid tar sites as for othercontaminated sites.In the case of strategies involving the removal of the acid tars for off-site licensed disposal orincineration (whether after pre-treatment or not), there will be a need to verify that theremoval exercise has met the agreed criteria. Normally, this will involve taking samples atthe base and edges of any excavation to confirm the degree and extent of any residualcontamination together with random sampling in other areas.If groundwater is to be remediated (for example, if there are free oils) then the normalprinciples will apply. Thus groundwater monitoring will be required at appropriate locationsaround the acid tar lagoon. Monitoring will be necessary before, during and afterremediation, until risks are properly managed and a statistically valid data-set has beenobtained that demonstrates that the concentrations and trends are acceptable. If groundwateris not to be remediated (i.e. if the strategy is one of mass removal of the source) thengroundwater monitoring post-removal over a similar (or longer) period will still beappropriate. This will be required in order to demonstrate the improvement in groundwaterquality and, where relevant, to demonstrate that natural attenuation is occurring in accordancewith predictions.If the remedial strategy involves stabilisation techniques such as DCR then it will benecessary to demonstrate that the agreed performance criteria are met in the finished product.If the product is to be disposed of or re-used on site (subject to any necessary wastemanagement licence) then consideration will be required of demonstrating longer-termperformance. In the case of an engineered landfill, this would in any case be addressedthrough the waste management licensing procedure.R&D <strong>Technical</strong> Report P5-042/TR/04 45