85 MGD Sewer Rehabilitation in Tempe Town Uses Sewer Pumps and HDPE Pipe for Upgrade

Tempe Town Lake Sewer Rehabilitation Project. This system successfully bypassed a peak flow of  85 MGD with a maximum pipeline capacity designed  to handle 110 MGD.

Tempe Town Lake is one of Arizona's most popular urban outdoor destinations, with more than two million people visiting each year to boat, fish and attend concerts, firework shows and a variety of festivals.  It is also one of the fastest growing urban areas in the United States.  Tempe Town Lakes sewer system needed to be upgraded to support a growing population.  Being an environmentally sensitive and public location, the construction site required careful attention.

When the sewer rehabilitation project contract was awarded to a major trenchless technology contractor, they selected Rain for Rent, Chandler, Arizona to provide equipment and service solutions for the bypass pumping portion of the project. 

The scope of the project required a complete high-flow bypass system consisting of pumps, piping and service technicians for the duration of the project.  Rain for Rent provided 111,000 feet (21 miles) of 20 to 24 inch HDPE pipe to bypass the existing sewer lines that ranged in diameter from 15 to 56 inches.  The six pump stations required twelve DV-300i, 12 inch; eight DV-400, 16 inch pumps, two DV-350, 14 inch and five DV-150i, 6 inch Power Prime™ pumps, along with two automatic-start Flygt submersible pumps complete with portable generators.  Sound attenuated pumps were used near noise sensitive residential areas.

Rain for Rent's Engineering Team designed a bypass pumping and piping system to handle the maximum flow rates projected by the City with a built-in safety factor.  This system successfully bypassed a peak flow of 85 MGD with a maximum designed pipeline capacity of 110 MGD. 

The project contractors, vendors and engineers diligently worked individually and as a team with the construction manager during the pipe inspections, which lasted over two weeks. 

One of the many pumping challenges involved a deep manhole with a 37 foot suction lift.  Vacuum prime pumps cannot prime with a suction lift this deep, so Rain for Rent designed a solution with an automated submersible pump system complete with float controls and powered by two large generators.   Additionally, unforeseen groundwater fluctuations caused an 18 foot deep suction pit's groundwater level to rise within 10 feet of grade.