For over 40 years, the City of Grand Island, NE operated coarse bar screens with 1-1/8″ bar rack openings. The bar screens operated as intended, but Staff found that this bar spacing allowed for significant bypass of material to downstream processes that proved problematic. The nature of screenings had changed over the years, and it was time to consider a new approach. In addition, the existing bar screens were simply showing their age and in continuous need of repair.
The new design criteria called for a peak flow of 50 MGD per channel (6′ wide by 25′ deep) and 3/8″ openings. So when it came time to consider these new flows, tighter bar rack spacing, and a worry-free design, staff didn’t have to look far to the East for their solution: The Vulcan Mensch Severe-Duty Bar Screens. The Wastewater Plant Engineer, Marvin Strong, PE, made mention that the City now removes 6 cubic yards of compacted material per week in comparison with 2 cubic yards of uncompacted screenings with their old bar screens. Doing the math, the new 3/8″ screen openings are removing approximately 10X more material than the old equipment did! Amazing! This new removal efficiency was further put to the test during start-up as a new interceptor system/hydraulic profile engaged the Vulcan Screens inundating the bar racks and frames with debris that had been entrenched upstream for who knows how long. “It was unlike anything we had ever seen!” Marvin noted. And the new screens performed as advertised. Standard 3/8″ thick side frames and dual rake arms are specifically designed to combat these severe loading’s, and the new washing presses are built to the same level of robustness. Ultimately, Maintenance Supervisor John Rundle summed it up best when he said, “We can’t speak highly enough of how nice the equipment is to operate now.”
We at Vulcan are extremely proud to have teamed with the City of Grand Island, Black & Veatch, and Garney Construction on this project as it is one of the most decorated facilities in the State of Nebraska. The plant has been recognized on both local and national levels including wins for “Best In Class – Large Systems” and the S.W. Innovation Award. Kudos to everyone involved in this fantastic project.