are over one kilometre distant; the nearest surface water body is over one kilometre from site. If future groundwater monitoring indicates a change in plume stability, an updated risk assessment should be performed. Dermal contact and soil ingestion (on-site commercial land occupants) Incomplete Depth of hydrocarbon impact and concrete cover over site. If concrete cover was altered, an updated risk assessment should be performed. Dermal contact and soil ingestion (off-site receptors) Incomplete Hydrocarbon impact contained within site boundaries. If future groundwater monitoring indicates a change in plume stability, an updated risk assessment should be performed. Volatilisation of hydrocarbon vapour from soil and groundwater to indoor and outdoor air (on-site commercial land occupants and off-site receptors) Incomplete Soil vapour monitoring indicates volatilisation of hydrocarbon vapour from soil and groundwater to indoor and outdoor air does not present a risk for commercial land occupants or off-site receptors. If on-site land use changes to a more sensitive use, or changes in hydrocarbon plume status are reported, an updated risk assessment should be performed. Dermal contact, soil ingestion and volatilisation of hydrocarbon vapour from soil and groundwater to indoor and outdoor air (maintenance/excavation workers) Not assessed If excavations in the vicinity of the plume are to be conducted, a risk assessment should be carried out before the works begin. Example A3: Simple text conceptual site model The following CSM was used to describe the rationale for soil sampling being undertaken on an industrial site, which was required to support an application for consent for soil disturbance. There was no change to the use of the site. The site is currently used and zoned as an industrial site, and this use will continue after the proposed soil disturbance works, which are temporary works to upgrade the storage area. Contaminants may be present in surface soils, as the area is unsealed and has been used to store hazardous substances (lubricating oils and paints) over a long period of time. Potential receptors are therefore confined to the permanent site workers – who may be exposed to contaminants in the soil during their day-to-day activities, and to construction workers, who may be exposed to contaminants during the proposed works. A detailed soil investigation will be undertaken to determine the concentrations of contaminants in shallow soil, to quantify the risk.
confidence is desirable, for example, unpaved areas or garden areas where an exposure pathway is complete. Selecting an appropriate sized hotspot, and determining the number of samples required to locate a hotspot, requires professional knowledge and experience, and must be supported by clear justification. The sampling points calculated are located in a plane and do not take into account vertical contamination throughout the soil profile (ie, the sampling point is the lateral location at which a soil sample is collected). Where the contamination is located in different soil strata, the number of sampling points may need to be increased to reflect the different vertical distribution of contaminants. Table B1 is not for the purpose of determining the number of samples required to characterise a site using a systematic sampling approach. Table B1 is only intended to provide guidance on the size of the hotspot a given grid size will detect.