At the St. Louis Water Company, a study demonstrated that water receiving proper pretreatment can be successfully filtered at rates of 5‐6 gpm/sq ft, with either a rapid sand filter or a dual‐media filter. Pretreatment requirements will vary with the quality of the raw water and should be determined on this basis. The pretreatment facilities utilized for this study had detention times based on a 3 gpm/sq ft filtration rate. The water treated had widely varying characteristics. Statistics show the range of raw‐water characteristics, turbidity of water applied to dual‐media filters, and turbidity of the filter effluent during 1967. The unit dosage of chemicals to achieve these results is also presented.

Burning coal, alternativesDear Sir: The article "How to Make Coal Burn Cleaner" (ES&T, January 1976, p 16), is particularly timely; we in EPA are most concerned with many environmental and energy related decisions facing the power Industry today. Our engineers have reviewed the several alternatives being offered to convert coal into electricity and other forms of energy. While coal gasification and liquefaction probably will have applicability to the generation of highquality fuels, we doubt that these technologies will be economically competitive with coal burning at power plants in the near future.As Mr. Train pointed out, EPA believes scrubbing to be a more practicable approach to the control of sulfur oxides at power plants. This conclusion is supported by a contract study conducted by the M. W. Kellogg Company entitled, "Comparison of Flue Gas Desulfurization, Coal Liquefaction, and Coal Gasification for Use at Coal-Fired Power Plants", (EPA-450/3-75-047), April 1975. The report shows that flue gas desulfurization technology is more fully developed than

In response to the recent “Viewpoint” by Abel Wolman (Journal AWWA January 1984), the author expresses concern about “detectable” levels of contaminants. As monitoring technologies improve, some amount of trace organics will be detected. Health effects should be researched further, putting them into perspective with other sources of the same contaminants and other risks humans face. Also, prevention at the source will be less costly than expensive treatment techniques. Wolman replies that his position on health implications of organics has been modified as it became evident that effects and risks of organics can often be studied only on a long‐term basis.

This article advocates greater involvement by the water utility industry in two major areas of water quality and monitoring. Detailed water analyses should be available to customers on an annual basis, which may mean expanded monitoring on the part of the utility for normal characteristics as well as for trace organics and manmade contaminants. In addition, the responsibility for research on health effects and treatment concepts should rest with the industry rather than with agencies of the federal government.