The coastal Marshes near Lymington overlooking the Solent and the Isle of Wight have long been valued for their ecological importance.  The saltmarsh, intertidal mudflats, sand dunes, shingle, brackish lagoons and grassland provide a rich variety of habitats for flora and fauna, including some species which are internationally scarce.  Not surprisingly, the area is now protected as a Site of Importance for Nature Conservation.  In contrast, the agricultural land immediately to the north of the Marshes has for more than 25 years been an important area of gravel extraction, supplying a local and regional need for aggregates.  With the landowner and minerals company, New Milton Sand and Ballast (NMSB) progressing towards the Marshes it became increasingly important to avoid a potential conflict of interests. 

NMSB were granted a modified planning permission during October 2000 enabling the removal of sand and gravels from along the northern boundary of the conservation site with the proviso that adequate measures are taken to protect and maintain the existing hydrological regime within the Marshes.  Faced with dwindling mineral reserves within other consented areas and increasing demands for the supply of gravels, NMSB are keen to bring this final extraction area into commercial use at the earliest opportunity. 

Long-term dewatering of this gravel working was not an option and wet extraction by dragline was not considered operationally viable by NMSB.  The preferred option of the operator and the regulators was to install an impermeable barrier around the proposed new operation.  RLCL were commissioned to design and obtain planning approval for a cement/bentonite slurry cut-off wall around the workings.  This received unanimous support from both the planning authority and Environment Agency, since this solution will enable the mineral to be extracted in the quickest and most economical manner, whilst the associated dewatering exercise will have no impact upon the hydrological regime prevailing within the Marshes. 

Senior Consultant, Owen Humphries, who has led this project comments “the installation of the cut-off wall in the Autumn of 2002 will precede NMSB’s gravel extraction programme.  This solution addresses the aspirations and expectations of all concerned.”