An important SO/sub 2/ control option available for utilities using Western coals and lignites is to use the alkalinity of the ash from such coals for SO/sub 2/ control. This technology, commonly called fly ash alkali (FAA) scrubbing, is presently used on eleven large-scale boilers and is the focus of this manual. The purpose of this manual is to serve as a guide to the utility planner who must select FGD technology. Its particular objectives are: (1) to help the planner assess the applicability of FAA technology to a particular situation; and (2) once this applicability is established, to develop a preliminary process design. Thus, the scope of this manual is limited to an overview of FGD technology, an examination of FAA fundamentals and operating experience, and preliminary guidelines concerning the design of various components of the FAA system. 106 references, 60 figures, 48 tables.