Digest 427 brings up-to-date the information contained in Digests 274 and 275 which are now withdrawn.

The scarcity and cost of suitable land is leading to the development of sites where there are deep deposits of fill. Occasionally cases are reported where serious failures have occurred. These reports should not obscure the fact that many buildings have been successfully built on fill; they emphasise the importance understanding the behaviour of fills, identifying potential hazards and adopting measures that will ensure successful development of these sites.

This digest is divided into three separate publications:

Part 1 provides a general introduction, describes the causes of settlement of fill and gives guidance on the likely magnitude of settlement in different situations. A simple classification of fill materials is based on estimated fill movements. Part 2 describes approaches to site investigation, techniques for improving the load-carrying characteristics of non-engineered fills, and aspects of foundation design for fills.

Part 3 (this publication) deals with the specification and control of placement of engineered fills.

This third part presents guidance for the specification and control of fills which are to be placed so that they can safely support low-rise buildings without the occurrence of damaging movements. Such fills are described as foundation fills. When new fill is to be placed, careful selection of the material and controlled placement should ensure that the fill forms an adequate foundation material. Part 3 is particularly relevant to building developments where relatively small volumes of fill are being placed (typically less than 50 000 m3) and consequently the resources available for design, testing etc are quite limited.

 The three parts give guidance only of a general nature and it must be recognised that the services of civil, structural and geotechnical engineers will usually be needed. More detailed information concerning building on fill is given in Building on fill: geotechnical aspects (BR424).

8 pages.