This paper describes a computer model used to compute the hydraulic conditions related to the operation of a pressure filter system providing the ability to evaluate many design alternatives that are not cost effective if performed manually. The computer model gives the ability to easily change: the piping and control valve configuration data; well pump curve; and receiving distribution system hydraulic grade line elevation. This allows the user to optimize selection and sizing of the filter face piping and control valves. The computer model was used to design the filter face piping and to size the modulating control valves for an 8.6 million gallon per day pressure filter water treatment plant. The plant is designed to reduce the source water iron and manganese concentrations to secondary maximum concentration limits set by the Safe Drinking Water Act. The computer model analyzed the hydraulics of approximately 50 different configurations of system head, well discharge conditions, and filter operation modes. Mathcad was used to prepare the computer model. The model was on screen-interactive and provided immediate update of results. The interactive environment allowed the design team to quickly evaluate alternatives and what ifs, allowing them to rapidly converge on final filter face piping and control valve design. The model program included graphs showing the degree of control valve opening that allow visual evaluation of results. The methods employed are applicable to other hydraulic modeling problems.
