RE: RE: another enviro reminder-dont ignore to native landsthe enviromental branch of saskatchewan wont allow the contamination of the major aquifer the Hatfield Valley aquifer systemGroundwater Pollution near potash mines in Saskatchewan,CanadaExcept for one potash mine west ofRegina all mines are located near major undeveloped freshwater aquifer systems. The sand andgravel of the majority of the aquifers were deposited during Pleistocene times.Infiltration of potash brine from the waste disposal basins into the underlying sediments andsubsequent incorporation into the groundwater flow system have caused irreversible damage.All waste disposal basins near the various potash mines are underlain by glacial driftdeposits of Pleistocene age. The drift deposits comprise all sediments overlying'bedrock' which, in most of southern Saskatchewan, consists of sediments such asclays, shales, silts, and sands of Upper Cretaceous age. The Pleistocene drift depositscomprise till, clay, silt, sand, gravel, and various admixtures depending on the mode ofdeposition.The drift thickness varies from less than 1 ft (30 cm) to greater than1000 ft (300 m) with an average of 300 ft (90 m) in the southern half ofSaskatchewanNotonly do the aquifers constitute potential fresh water resources of great magnitude,they also represent the permeable paths for the migration of liquid waste. Most surfacewater bodies, for example, receive a considerable volume of water through dischargefrom these aquifers. The origin of the aquifers, their position in the section, arealextent, development, type and uniformity of sediment, and interrelationship isdirectly related to the glacial history of the Pleistocene epoch. It is therefore of utmostimportance for the protection of the environment from large-scale irreversiblepollution that the stratigraphie framework is known in sufficient detail both on a localand regional scale.deep-well disposal of liquid waste is not the panaceafor waste disposal problems, because the liquid waste is placed in an active hydrodynamicenvironment where it is committed only to temporary and not permanentstorage. This means that the representation of the method as either final or permanentis unrealistic and dangerous.Subsurface disposal operations that are hastilyconceived, inadequately investigated, improperly equipped and insufficientlymonitored can lead to serious and often irreversible damage to the environmentcollapse structures aresimilar to Graben type structures and are characterized by near-vertical normal faultsExcellent examples of collapse structures inSaskatchewan were described by Christiansen (1967, 1970). The diameter of thestructures varies from 1000 ft (300 m) to several miles.The danger of the salt-collapse structures is that they could constitute highlypermeable vertical paths for movement of fluids. Brine injected into a formation intersected by several collapse structures could conceivably migrate upward in thesestructures and pollute freshwater aquifers near the surface (similar migration couldhappen in those areas where unplugged or improperly abandoned testholes penetratethe disposal formationMany of the future management problems and the environmental implications of thewaste disposal basins near most potash mines might have been avoided if detailedhydrogeological information had been available for consideration before the time ofdisposal basin site selection. Significant provincial and federal legislation has since beenpassed for the protection of the environment. Provincial legislation, in particular, isdesigned to ensure that comprehensive hydrogeological data will be available and willbe taken into consideration in the future selection of additional waste disposal basins.To minimize the waste disposal problems industry should consider both waste volume reduction within its operation and alternative waste disposal techniques suchas backfill of solid waste and deep-well disposal of liquid wastes.Deep-well disposal should only be practised in those areas where the subsurfacehydrogeological environment has been properly defined and found suitable. Earlyrecognition of the hazards presented by the subsurface disposal method and of itsconsequences is imperative to avoid costly mistakes, serious accidents, and oftenirreversible damage to the environment