§ Sir Hugh Rossi
asked the Secretary of State for the Environment how many sewer collapses or failures there are in England and Wales each year; whether there are indications that these are increasing with the age of the systems; and if it is yet necessary to prepare a programme of replacement and renewal rather than of ad hoc repairs.
§ Mr. Waldegrave
In 1981, 3,228 sewer failures in England and Wales were reported to the Water Research Centre, of which 2,177 were collapses. Seventy three per cent. of failures concerned pipes of 9in. —225mm.— diameter or less. The survey data suggested that the frequency of failure would increase with age, but in the 1982 survey only 1,689 collapses were reported. There is insufficient data to establish the trend.
The water authorities' investment programmes include provisions for replacement and renewal of sewers and in 1982–83 £216 million was spent on capital account on sewerage. The WRC is expected to publish shortly a sewerage rehabilitation manual of guidance to assist water authorities in assessing sewerage problems and deciding the most economic approach to remedial work.