Northwest Water, supported by Halcrow, were investigating the exposure and potential partial floatation of a major outfall pipeline on the Fylde Coast in Lancashire.  Northwest Water asked HR Wallingford for specialist support in diagnosing the causes of the exposure and in designing a remedial solution.

The scope of work included extensive assessment of long-term stability of trench backfill. The study comprised field measurement (sedimentological and geotechnical investigations), laboratory tests, numerical modelling of erosion and wave-induced liquefaction and overall interpretation.