Phase II – Site investigation

Apple Environmental can assist in undertaking soil contamination and land contamination assessments and surveys. A contaminated land investigation may start or end with a desk top study, or continue on into a complete contaminated land survey with soil sampling investigation.

If a Phase I report identifies a potential source pathway receptor linkage, a Phase II intrusive investigation will be required.

This may require the drilling of boreholes or digging of trial pits at locations across the site in order to obtain samples of soil and where reached, groundwater for chemical analysis. The number of locations, the depth and the chemical suite analysed will depend on the information gathered during the Phase I investigation or site survey.

All surveys and site investigations are undertaken in accordance with the current British Standard, BS10175:2011.

Assessment of risk to potential receptors

This is concerned with looking at contaminants in soil to human receptors. Risk to human receptors is usually determined by comparison of soil concentrations to soil assessment criteria.

The CLEA model developed by the Environment Agency is designed to produce generic or site-specific assessment criteria for soil contaminants at a particular site. Where contaminants in the soil exceed the assessment criteria contamination is considered to be potentially significant.

For generic assessment criteria sites can be classified as allotments, residential, commercial and industrial. The assessment criteria are developed by considering the toxicological data of the contaminants and potential pathway linkages. The assessment criteria therefore for residential end use are far lower than that of commercial or industrial as the availability of garden space in which residents spend time and could potentially grow vegetables increases the pathways to the receptor.

The Environment Agency has used the CLEA model to develop soil guideline values (SGVs) for a number of contaminants for allotments, residential and commercial/industrial end use. These are always used where available before considering other sources and modelling.

Pollution of controlled water

In the absence of any UK standards reference is made to non UK published guidelines such as those generated by USEPA to determine the significance of contaminant concentrations with groundwater and surface water samples.

A number of models are available for quantifying the effects of contaminated groundwater and surface water, such as the Environment Agency P20 model.