This paper focuses on two sites in the Mount Pleasant -
McCormacks Bay area of Christchurch where residential development has taken place either within or immediately adjacent to
former quarries for the extraction of volcanic rock. At the Quarry Road site
less overburden was dumped on adjoining land around the turn of the century, and
c.1980 dwelling and related construction took place on approximately 6 m of
relatively loose fill material without the recognition of its presence or
geotechnical characteristics. Subsequent settlements led to abandonment of a
swimming pool and the underpinning of the 3-storey architect-designed house,
whilst litigation brought by the owner resulted in findings of negligence
against both the architects and engineers. At the Tramways Quarry site the
Council approved subdivision of the former quarry area in the early 1980s
without requiring any geotechnical evaluation of batter stability or related
issues. During development it became apparent that significant blast damage had
occurred to rock faces, necessitating a variety of remedial measures,
and that waste materials had been dumped down faces without
regard to long-term stability. Both case studies confirm the requirement for
careful documentation of former quarry sites by territorial local authorities as
part of their administrative function, and for detailed engineering geology and
geotechnical evaluation of such areas prior to any residential use of the
land.