Dear Martin (and Jiscmail list)
SEPA recommends that operators in Scotland considering the use of PFA in grout should refer to the BRE Environmental Code of Practice: “Stabilising Mine Workings with PFA Grout” which is available for purchase from their website at http://www.ukqaa.org.uk/Environment/PFA_grout_flyer.pdf. In essence the Code confirms that there is a risk that PFA use can result in adverse effects on the water environment as a result of the presence of small quantities of soluble substances that can leach into the surrounding groundwater during or after grouting operations. Concentrations of these substances entering groundwater can be in excess of what would be acceptable.
As a result the operator should undertake a risk assessment to determine if the grout mixture used will give rise to:
i. Entry of measurable amounts of hazardous substances into groundwater
ii. Entry into groundwater of non-hazardous substances in quantities sufficient to cause pollution of the water environment
The level of risk assessment required will depend on a number of factors, including the size of filling operation, proximity to water environment receptors, the properties of the materials selected and the nature of the specific site being considered. The Code therefore recommends a tiered approach: the level of detail required increases at each tier as the assessment focuses on those risks identified as having the highest priority at the previous stage. This allows the level of detail required in conducting the assessment to be proportionate to the nature and complexity of the risk being addressed.
SEPA has recently released a Position Statement explaining how impacts from inputs into groundwater should be assessed which will be useful for the higher tiers. This may be found at http://www.sepa.org.uk/water/water_regulation/guidance/pollution_control.aspx as WAT-PS-10-01: Assigning groundwater assessment criteria for pollutant inputs.
Note that some references in the Code are not relevant in Scotland, for example Source Protection Zones do not exist, and the regulatory regimes between England and Scotland are different.
i and ii above represent Rules a) and c) of General Binding Rule 16 of the Water Environment (Controlled Activities) (Scotland) Regulations 2005. If the risk assessment demonstrates that these rules are met then no further authorisation will be required. If these rules are not met then authorisation of the grouting operation by SEPA will be required.
In general SEPA considers that careful use of recommended mitigation measures will allow most small and medium sized grouting activities to be authorised using GBR 16. Where a risk assessment indicates that the rules of the GBR will not be met, or there is any doubt on how to proceed, the operator should consult SEPA.
I trust this provides some clarity as to SEPA's appproach on this mattter
Best regards
Gerry McGarrity
Contaminated Land Specialist
SEPA East Kilbride
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