A new £25m residential development of about 250 apartments in Altrincham consists of a cantilever structure extending over the adjacent canal, and was built on a brownfield site which presented a number of design and construction challenges. The superstructure consists of a series of braced steel frames built off the ground floor slab which covers the below-surface car park. Construction of the basement parking required the removal of about 20000 cu m of soil. The high water table required the construction of a continuous reinforced concrete retaining wall combined with a sheet pile wall. Water extracted from the site required mercury and hydrocarbon removal prior to disposal. The ground consisted of clay, mudstone, sandstone and some peat lenses, leading to the choice of single large diameter piles ( up to 900 m ), situated directly under column or wall positions, with a reinforced concrete flat slab. The piles were socketed into the bedrock.