NCP Contracting are proud to be able to offer our services in the remediation of construction sites.

We have the equipment within our fleet to prepare all types of land for development and our experience within this field enables us to control and handle hazardous waste.

Excavation and replacement (dig and dump)

Excavation is commonly used where a detailed site investigation has identified significant contamination in the soil or unacceptable discharges to water bodies. For this remediation method the contaminated soil is removed to a licensed landfill, or to an area that has consents to receive contaminated material. The removed soils or sediments may need to be analysed to confirm they comply with landfill waste acceptance criteria as specified in the Hazardous Waste Guidelines (Ministry for the Environment 2004b). Where soils from sheep-dip sites fail the toxicity characteristic leaching procedure (TCLP) tests required by most landfills, prior treatment to reduce the contamination will be necessary. Concrete (eg, from the draining platform) can also adsorb dip chemicals, so where no risk management plan is to be instituted for a site, old dip-bath structures should be removed together with the soil.

Validation samples will need to be collected from the soil remaining at the site to prove that the contaminant concentrations comply with the remediation goals (see section 5.6). Remaining holes or depressions may then be covered with clean material. This option is practical in a farming context. In the past, private landowners often "decommissioned" their old sheep dips by doing the dig and dump themselves without supervision, often unaware of proper remediation procedures.

This option is likely to be economic mainly for small volumes of soil, but may also be appropriate for extensive contamination on large developments where the developer considers the economic benefits justify the expense.