Virgin Excavated Natural Material (VENM) is defined in the Protection of the Environment Operations Act 1997 as ‘natural material (such as clay, gravel, sand, soil or rock fines) that:
* has been excavated or quarried from areas that are not contaminated with manufactured chemicals or process residues, as a result of industrial, commercial, mining or agricultural activities; and
* does not contain any sulfidic ores or soils or any other waste.
A material can only be classified as VENM if it has been excavated from an area that is not contaminated with other waste materials or by manufactured chemicals. Identifying previous land uses is a useful first indicator of contamination. The possibility that a previous land use has caused contamination of a site must be considered when assessing whether an excavated material is VENM. Please note, in the instances where an excavated material cannot be classified as VENM, it may be eligible for reuse under as Excavated Natural Material (ENM).
Classification of VENM requires certainty that the material concerned is not contaminated.
Where it is uncertain whether an excavated material can be classified as VENM, a chemical assessment is needed. The analytes generally tested for include:
* Heavy Metals (As, Cd, Cr, Cu, Ni, Pb, Zn, Hg)
* TPH (total petrleum hydrocarbons)
* BTEX (volatile organics)
* PAHs (polycyclic aromatic hydrocarbons)
* OCPs (organochlorine pesticides)
* PCBs (polychlorinated biphenyls)
* Asbestos
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I think so that soil investigation task is very important for contruction and environment control.
Using VENM as backfill soils:
What is the risk of contaminating groundwater by using imported, classified, VENM which has higher background metals concentrations compared to that of the receiving site. For example, a quarry which we’re sourcing VENM from has high concentrations of naturally occurring background metals. We’d like to use this VENM to backfill an excavation which the depth of the excavation is below the water table. If we backfill with this VENM, will the groundwater become impacted with dissolved metals and is this considered polluting under the POEO Act? And is this considered soil contmaination as well?
Without seeing the actual analytical reports of the VENM it is difficult to categorally answer yes or no to your questions. Generally, the risk of contaminating a site through using backfill material classified as Virgin Excavated Nateral Material (VENM) is minimal. In the situation where the VENM has natural elevated metal levels there are a couple of things that you can do to assist you deciding whether to import the VENM or not, such as:
* Compare the levels of analytes within the VENM to the guideline parametres allowed onsite.
* Examine the leachability of the metals within the VENM through TCLP analysis.
* Collect samples from the groundwater prior to importing the fill to confirm what the background levels of the metals of concern are within the groundwater.
* Source material from another location and do not import it onsite. VENM is generally always available.
I hope this helps. If you need further assistance please call and I am always happy to have a chat.