Waihi North Project Preliminary Site Investigation (Ground Contamination) Williamson Water & Land Advisory Limited 45 4. Preliminary Conceptual Site Model A CSM indicates known and potential sources of contamination, routes of exposure (“pathways”), and receptors that may be affected by contaminants moving along those pathways (Table 11). Receptors may be people or environmental. This CSM is considered “preliminary” as soil sampling has not been completed, thus the identified pathways will not exist if contamination is not present. The HAIL assessment indicates that the most likely sources of contamination across all WNP sites include: • Mining activities including storage of dangerous goods, tailings dams and other associated activities. • Fuel storage. • Explosives storage. • Other chemical storage and use such as livestock drenches. • Transformers. • Workshops. • Asbestos in historic buildings. • Accidental release of contamination through spills or fire events. • Treatment of wastewater. Potentially contaminated areas are highly localised and small in area and volume compared to the scale of earthworks proposed. We have undertaken the source – pathway – receptor analysis (CSM) based on this context (Table 11 below). Potentially complete pathways can be managed through standard earthworks controls and removal or controlled mixing and placement of affected soils if necessary. A robust SMP setting out procedures to manage the above risks is required to inform and direct contractors and support the resource consent by informing Council of these methods. WWLA has prepared an SMP to support the resource consent. This document will be updated to support construction closer to the commencement of works. Table 11. Preliminary CSM (entire WNP area) Source Receptor Pathway Assessment Contamination from a range of sources in current operational areas. Site end users and construction workers during redevelopment. Exposure via inhalation of dust potentially containing contaminants including asbestos fibres. Skin contact with soil containing contaminants. Ingestion of contamination through poor hygiene practices. Potential Complete Pathway: Contaminant concentrations may exceed human health criteria in localised areas as highlighted in Section 3. Actual contaminant concentrations will be defined through pre-works testing. It is expected that any contamination present will be managed in isolation prior to bulk earthworks, through excavation and offsite disposal. Containment of any identified contamination beneath structures such as buildings and within the TSFs is also possible. Ecological receptors at the nearest surface water bodies at the site and receiving soils site (for all contaminants excluding asbestos). Discharges of dust, sediment or surface water runoff to surface water bodies. Potential Complete Pathway: As above any impacted soil is expected to be localised and thus environmental effects easily managed by materials segregation and removal/ mixing and standard earthworks controls. The wide network of stormwater drains etc, discharging to the WTP, will also assist in managing potential contamination discharges.
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