Following college and before joining CH2M HILL, Cliff joined Metcalf & Eddy (1958-1964) before moving on to the U.S. Army Corps of Engineers (1964-1966) and returning to Metcalf & Eddy (1966-1971). He then went to Wright Pierce, Barnes and Wyman (1971-1972) and again to Metcalf & Eddy (1972-1986). During this period, Cliff was administratively and technically responsible for several municipal and industrial waste projects from conception through startup and operation, both in the U.S. and overseas, representing over $8 billion in construction. Major projects included Project Manager for the design of a 60-mgd Hartford Water Pollution Control Plant (1968-1969) and Project Manager for the preliminary design of 309-mgd Advanced Wastewater Treatment Plant for the District of Columbia and the final design of additional primary facilities (1970-1971). Additional major projects included an intensive 6-week study using mathematical modeling for development of billion-dollar water and wastewater capital improvements program for the City of Austin, Texas (1983), and the design and construction of a contaminated groundwater treatment system for a major U.S. Air Force installation (1985).
Cliff's international work included serving as a Project Advisor for a Brazilian engineering firm as part of the Sanegran Wastewater Treatment Project in Sao Paulo (1978-1981). He also served as Project Director for design review and construction oversight of 12 construction contracts for a major water supply project in Bangkok (1979-1983).