Please note that this Information Paper relates to the 2006 edition of the associated report. BR488 has now been superseded by BR509, published in 2009. Since the 1970s, many disused mine workings have been successfully stabilised by filling with grouts based on pulverized-fuel ash (pfa) and Portland cement. However, concerns have been expressed over the potential for contamination of controlled groundwaters by bleed water and leachate released from pfa grout, disruption and dust arising from the work, the effect on land and property prices, and the risk of classification of the land above the workings as contaminated. This Information Paper summarises new guidance on the selection of environmentally compatible and cost-effective materials and techniques, published in a detailed BRE report (BR488). It is based on information in the literature, laboratory studies at BRE, data from the use of pfa grouts and expertise from an industry steering group. 4 pages.