The Central Regional Wastewater System facility was constructed in multiple phases over the history of the facility. The Phase I/II, or north headworks included 10 aerated grit basins sized for 20 MGD each with a peak capacity of 200 MGD. The aerated grit basins were a significant source of odors and did not perform as well as the Phase III headworks that consists of four vortex grit basins. CP&Y developed an innovative approach for converting the existing aerated grit basins into vortex grit removal basins. By converting the aerate grit basins the capacity was increased to 350 MGD by using five Model 70 vortex grit basins.
The conversion of the aerated grit basins included innovative construction techniques necessary to install piers to support the new grit basin structures within an existing building with limited head space. Construction equipment for drilling piers inside the building was located and the conversion was constructed for less than the originally recommended odor control project, which had proposed covering the aerated grit basins and treating exhaust gasses from the aerated basins. The original capital outlay for the initial odor control project also allowed the construction of a covered grit separation facility adjacent to the existing grit building. Additionally, six new grit pumps were installed, two new Teacup™ grit separation units with Grit Snail™ dewatering units were installed inside the new grit separation building. The conversion also included new electrical equipment and a new SCADA system. This project was recognized by both the Texas and National American Council of Engineering Consultants (ACEC) Excellence in Engineering.
Upon completion and commissioning of Phase I/II grit improvements, CP&Y began design for the renovation of the Phase III (South Headworks) facility. Renovation of the South Headworks includes relining influent channels with corrosion resistant coatings, rebuilding four 8-foot climber bar screens, the addition of new screenings conveyor, rehabilitation of four 70 MGD Pista Grit™ units, replacing six grit pumps with new pumps, and replacement of two Teacup™ grit separation units with Grit Snail™ dewatering units. The renovations also included new electrical equipment and a new SCADA system. Upon completion of the Phase III headworks improvements, the CRWS facility will have a grit capacity of 630 MGD.
Design of Grit Removal System
Trinity River Authority
Five 70 MGD
Pista Grit™ Units
Six 250 Grit Pumps