WARRENDALE, Penn., Dec.15, 2004 -- USFilter has re-engineered its MULTICRETE II™ monolithic concrete filter underdrain system used in water and wastewater filters.  The new design increases the underdrain system's strength and simplifies the installation process. 

The NSF Standard 61-approved underdrain can weather the harshest downward and upward pressures subjected during years of filtration and backwash.   To ensure the underdrain is capable of resisting higher pressures and better handling of cyclic loading, the underdrain form was re-engineered to increase allowable floor thickness.  The forms support loads from installation traffic and wet concrete while minimizing deflecting to less than one-eighth of an inch.  Based on filter system requirements, the underdrain can be designed for a range of downward and uplift loads.  Standard system design meets the structural requirements of ACI 318 standards.

To simplify installation, the false-floor underdrain consists of plastic form work used to support concrete and reinforcing rebar during the installation process.  Underdrain nozzles, installed after the concrete is cured, collect filtered effluent and distribute water and air during backwash.  In addition, a unique fastening system has been developed to allow a simple ¼ turn rotation to secure the inserts in place saving installation labor and improving quality control during installation.

While the underdrain system has been improved to benefit installers and plant owners, the working performance remains the same as the previous designs.  MULTICRETE II underdrains have been in use at hundreds of water and wastewater filters for nearly 20 years.