In addition, one needs to consider whether gouting works would displace contaminated groundwater, which could impact on other parts of the water environment,

Therefore the previous response, ammnded for completeness, would read as follows:

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. 

In addition to the effects dealt with in the BRE Code, grouting operations in Scotland are often to fill voids left from coal mining operations where injection of grout may displace poor quality groundwater now filling these voids and this may impact upon other parts of the water environment. 

As a result the operator should undertake a risk assessment to determine if injection of the grout mixture 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

iii.  Displacement of poor quality groundwater that will impact upon other parts of the water environment 

The level of risk assessment required will depend on a number of factors, including the size of filling operation, the 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. In addition, the approach described by the Code does not describe an assessment of iii.

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 and groundwater displacement will not give rise to impacts then no further authorisation will be required. If this will not be the case then authorisation of the grouting operation by SEPA will be required.

In general SEPA considers that, provided displacement of poor quality groundwater will not impact upon the water environment, 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 this will not be the case, 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