Planning for gypsum geohazards in Lithuania and England

The rapid underground dissolution of gypsum, and the evolution of the gypsu m karst in Lithuania and England, results in subsidence problems which can make construction difficult. The natural dissolution yields sulphate-rich g roundwater of poor quality and the karst is susceptible to the rapid transm ission of pollutants. In the north of Lithuania gypsum karst is developed in Devonian gypsum. Her e the towns of Birai, Pasvalys and the surrounding countryside suffer subsi dence and some buildings have been damaged. The majority of the potable wat er in these areas is derived from groundwater extracted from sandstone sequ ences that underlie the gypsum. In Lithuania conservation measures have bee n introduced to control agriculture and prevent pollution of the gypsum kar st. These measures include environmentally-friendly farming, restrictions o n land use and exclusion zones around subsidence hollows. In England subsidence caused by the dissolution of Permian gypsum has cause d severe problems in the vicinity of the town of Ripen. Numerous buildings have been damaged and new sites are difficult to develop. Here formal plann ing regulations have recently been introduced to help to protect against th e worst effects of subsidence resulting from gypsum dissolution. (C) 1999 E lsevier Science B.V. All rights reserved.