Report No FR0093

Oct 1990

To assess the effects on the marine environment of discharge of sewage to coastal waters via correctly designed sea outfalls.

The use of the sea for sewage disposal has come under increasing scrutiny from the public and from other countries bordering the North Sea. There is a need, therefore, to understand and quantify the environmental impact of sewage discharges from modern long sea outfalls.

1. At both Weymouth and Tenby, the whole survey area was affected to some extent by sewage-derived material, but both outfalls were operating within the dispersive and assimilative capacities of the environment.
2. The studies at Tenby and Weymouth indicated that well-designed and operated long sea outfalls appear to be an acceptable means of waste disposal.

Broad-based environmental surveys were carried out at case-study outfalls at Tenby and Weymouth over a three year period. Studies included: sediment sampling on coarse grids and near-outfall transects; bioassays on mussel scope-for-growth, bivalve larval development and Microtox; uptake of taint compounds; sewage sampling; distribution of rotavirus; dispersion studies.

Copies of the report are available from FWR, price £15.00, less 20% to FWR Members.