“…Certain recommendations and warnings relating to operations and brought out as a result of the visits, must be given: [1] Plug valves give trouble in maintenance and operating when body feed must pass through the valve; [2] according to the operators, stone elements require more frequent cleaning and replacement than other types of filters should have facilities for removing the heads without the use of overhead cranes or A frames; [7] the filter elements should be independently removable from the tube sheet; [8] the plant layout should be practical and designed for convenience of operation; [9] reciprocating service pumps should not be used with diatomite filters; and elements; [3] the body-feed proportioning pumps do not have sufficient capacity to be effective in periods of high turbidity-with high strength slurries, maintenance becomes a problem and operation becomes erratic; [4] there is a definite need for better flowrate indication and control; [5] the system of pipes should permit backwashing with filtered water; [61 the [10] prechlorination of raw water should be required in municipal filtration plants.…”