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<br />,..nfi <br />'i;..;t." <br /> <br />M <br /> <br />METROPOLITAN WATER DISTRICT <br /> <br />as appropriate arrangements can be completed with the county <br />authorities. <br />Periodic measurement of deformation of Copper Basin dam was <br />continued. The observations indicated that expansion of interior <br />concrete, which previously had progressed at a substantially <br />uniform rate since construction of the dam in 1938, is lessening <br />appreciably, pointing to a possibility that the internal reactivity <br />of the concrete is gradually ceasing. Laboratory investigation <br />conducted by the U, S, Bureau of Reclamation on cores taken from <br />the dam has indicated that the volume change in the concrete is <br />caused by interaction of reactive aggregate with the alkali in the <br />cement. <br />Ath,ntion was given to problems arising in connection with the <br />performance of the automatic pressure regulating and relief valves <br />on the Palos Verdes feeder. With increasing flows in the feeder, <br />and the rapid changes in rates of diversion occasioned by the action <br />of automatic regulators on the connected water systems, it has <br />become progressively more difficult to control the pressures in the <br />District lines. Investigation was made of various methods of com- <br />pensating the pilot controls on the regulating valves to improve <br />the response to sudden changes in diversion, and to prevent Qver- <br />travel of valve movement. <br />Public improvements were constructed extensivel.\' in the regions <br />traversed by the District system, requiring review of numerous <br />plans of highway, flood control, sewerage, and storm drain projects <br />for purposes of correlation with District facilities. <br /> <br />I <br />