The Village of Bensenville had been experiencing an inordinate amount of water main breaks within the Jefferson Street Corridor. This area consists of Jefferson Street and eight adjacent side streets of residential areas with water main constructed and replaced between the 1950’s through the 1970’s.
Jefferson Street consists of 3,500 lineal feet of eight-inch cast iron water main with the side streets totaling almost 6,500 lineal feet of six-inch diameter pipe.
Prior to design of the replacement water main, the Village needed to determine the probable causes for the water main breaks. This approach investigated potential sources of water main failure including stray electrical current, inferior materials and corrosive soils. TAI retained the services of SEECO Consultants Inc. who completed twenty-five soil borings within the project limits. Ten of these samples included testing for corrosive soils in accordance with the Ductile Iron Pipe Research Association (DIPRA) ten-point test. This test assigns a numerical value to various chemical and physical soil properties. If a soil sample receives a score of ten cumulative points the soils are categorized as corrosive and preventative measures are recommended.
In Bensenville, all but one of the ten soil samples was deemed corrosive based on low soil resistivity. With the pipe laid directly on virgin earth, the soil acted as a conductor allowing electrical differences on the surface of the pipe to easily be transferred leading to corrosion along the bottom of the pipe. TAI prepared a Project Design Report (PDR), which included the findings of the water main failure analysis, conceptual water main layouts and corresponding engineer’s estimates. After reviewing and evaluating alternatives, including polyethylene encased ductile iron, high-density polyethylene (HDPE) and PVC water main, the Village determined that PVC was the most cost effective choice.
TAI has completed the design of 10,000 lineal feet of 12-inch and 8-inch water main under three separate phases. All three projects were completed under the budget and awarded price.