THE LEGACY OF SALT MINING AND CHEMICAL INDUSTRIES IN CHESHIRE, ENGLAND

9th International Multidisciplinary Scientific GeoConference - SGEM2009, www.sgem.org, SGEM2009 Conference Proceedings/ ISBN 10: 954-91818-1-2, June 14-19, 2009, Vol. 2, 637-644 pp

ABSTRACT

The town of Northwich in Cheshire, England has played host to the salt mining industry
for 300 years and was the cradle of the modern heavy chemical industry with which it
has been associated for approximately 200 years. Historically, the dumping of waste
from these industries on adjacent land was unregulated leading to substantial
accumulations of ‘legacy industrial solid waste’ (LISW) arising from many processes
including brine evaporation and the Leblanc and Solvay processes for soda ash
production. This project aims to assess the ongoing environmental impact of LISW
around Northwich through a combination of detailed land use history assessment from
archival maps and other records, combined with field mapping and laboratory analysis.
Part of the site has a history of salt mining and brine extraction with subsequent mine
collapse and subsidence causing the formation of saline ponds or “flashes”. These have
been used subsequently as waste disposal lagoons by the chemical industry and their
containment storage volumes increased with engineered bunds constructed from ash,
lime and clinker. Representative samples of LISW have been characterized by optical
microscopy, scanning electron microscopy (SEM), X-ray diffractometry (XRD), and Xray
fluorescence (XRF). The analytical data have been interpreted in the context of the
site’s history since the mid 19th century enabling the construction of a conceptual
model of environmental impact over the past two centuries. The rise and decline of the
local industry is revealed through the appearance and dereliction of factory works, and
the expansion of the waste tipping areas, whilst advances in production technology and
changing raw material sources are evident through changes in LISW type and
composition. The results of this study have revealed that although the LISW does not
pose a toxic risk, it continues to have a substantial effect on the local environment and
water courses.

Keywords: salt mining, chemical industry, legacy industrial solid waste (LISW).