Lewis Clark was a hydrogeologist who, like most of his generation, came into the discipline from another area of geology, and who helped to mould the subject into its present form. He was born in Yorkshire in 1937 and graduated in Geology from the University of Leeds in 1960, proceeding immediately to gain, in 1963, a Leeds PhD on the metamorphic aureole and associated mineralization of the Ennerdale Granophyre. The hardrock interest continued with his first professional posting in the Uganda Geological Survey (1963-68), mapping and mineral surveying before supervising the drilling and testing of water supply boreholes and managing regional groundwater surveys.
His interest in hydrogeology developed during eight years (1968-76) with Hunting Surveys, during which time he carried out field and desk hydrogeological studies in Africa, Greece, a major water resources survey in Thailand and (as Senior Hydrogeologist and Deputy Project Manager for the Additional Water Supply Project) in Saudi Arabia. Lewis returned to the UK in 1976, when he joined WRc. His first project at WRc was to supervise the scientific input to the latter stages of the Shropshire Groundwater Scheme. The scheme had started in the early 1970s to regulate the river Severn with groundwater abstracted from the Triassic Sandstone aquifers surrounding the river and its tributaries above Ironbridge. However, the emphasis of his work swiftly changed towards the critical, but at the time poorly studied, fields of groundwater quality and pollution. His early studies included the impacts of discharging sewage effluents to the Triassic Sandstone and Chalk aquifers, and groundwater problems resulting from the spreading of slurry from intensive piggeries.
By the early 1980s he had begun the investigations of the sources, transport and fate of hydrocarbons, halogenated solvents and pesticides, for which he is best remembered. The investigations included pesticides in the Granta catchment, solvents in the West Midlands and Luton/Dunstable areas, and jet fuel spills at Heathrow. His expertise, and practical experience of water resource surveying, was applied as English language editor of an UNESCO manual on Geology and the Environment, as the result of which in 1991 he was chosen to lead a DTi overseas technical mission to Czechoslovakia to study groundwater problems. During his time at WRc he worked also in eight European countries, including Russia, in Japan, Egypt, Nigeria, Bolivia and the USA. In 1997 Lewis retired from WRc as Principal Hydrogeologist and set up Clark Consult Ltd, from which he continued to provide hydrogeological and contaminated land consultancy to a wide range of clients. During 2002 he acted as an evaluator in five African countries on an UNEP project on Urban Pollution of Surficial and Groundwater Aquifers.
Lewis published papers on all aspects of his work, including the Geological Society Professional Handbook on Water Wells and Boreholes, which he was revising with Bruce Misstear at the time of his death. He wrote numerous reports for clients in the UK and abroad. His contribution to the development of hydrogeology was recognised by his peers in the award in 1997 of the Whitaker Medal by the Geological Society.
Lewis married Joan in 1961 and she accompanied him on his overseas postings during his time with Hunting Surveys. He was a social person who enjoyed discussing work, and many other issues, and passing on his knowledge to other people. It was natural that he should become involved in lecturing, initially on the theory and practice of borehole construction for the PSA (1982-90) and later on aspects of contaminant hydrogeology on the MSc course at the University of Reading (from 1993) and at University College, London, where he was appointed Visiting Professor in Hydrogeology in 1993. His greatest contribution is probably the numerous hydrogeologists who gained their enthusiasm for the science through contact with Lewis on formal courses, at meetings and over a pint in the pub.
In addition to his scientific expertise, Lewis was an accomplished amateur artist and craftsman. After retiring from WRc he was able to enjoying painting the river at Henley on Thames, where he lived, and constructing a colourful dinosaur in his back garden, which he excused as being for the benefit of his grandchildren. He will be missed by Joan, their children Richard, Kathryn and Nicholas and grandchildren Benedict and Rhiannon, and by his many professional friends.
Chris Young