Water required is determined by the mix design minus the native water in the material to be mixed. Water is fed from an outside source into the plant’s 850 gallon on board water tank, which acts as a surge tank. This water is fed at the design rate into the mixing chamber by two hydrostatic 2-inch ITT Jabsco flexible impeller positive displacement water pumps. These pumps provide a continuous, uniform flow and have a maximum capacity of 40 tons per hour. An Endress+Hauser Promag 33F Electromagnetic Flow Meter, which features empty pipe detection, creep suppression and auto zero, measures the flow rate. This mag-meter has no moving parts, requires no calibration and provides an unobstructed flow tube for better than ± 1/2 % accuracy (manufacturer’s specifications available upon request).