December 15, 2025

HeadCell® Eliminates Chandler, AZ’s Punishing Grit Problem

HeadCell® Eliminates Chandler, AZ’s Punishing Grit Problem

Background

Located just 20 miles from downtown Phoenix, the city of Chandler, Arizona, has experienced massive growth over the past four decades. In 1980, the city had a population of less than 30,000. Today, it exceeds 250,000, driven by the rapid expansion of technology and major employers like Intel®, which employs nearly 12,000 people in the region. This population boom placed significant strain on the city’s wastewater infrastructure. 

The Chandler Airport Water Reclamation Facility (WRF) was built in 1998 and is one of three WRFs in the area. Given the scarcity of water in south-central Arizona, Chandler reclaims and reuses 100% of its wastewater. The effluent meets Class A+ water standards, allowing direct use in lakes, golf courses, aquifer recharge, and landscape irrigation. In 2009, the plant underwent a major expansion to treat 15 MGD (57 MLD). At the time, the $76 million project was the largest capital improvement in the city’s history. Over two decades, the facility expanded four times to reach its current capacity of 27 MGD (102 MLD). Despite these upgrades, one critical issue remained unresolved: grit removal. 

 

The Problem

From the start, the plant operated without a grit removal system. As flows increased, grit accumulation caused severe operational challenges, including frequent maintenance across multiple processes, reduced operating capacity, shortened equipment life, and increased energy costs due to grit-laden aeration basins. To manage the problem, the plant hired contractors every two to three years to remove accumulated grit—a costly and labor-intensive process that consumed hundreds of thousands of dollars. 

Determined to eliminate this recurring expense, Chandler engaged Wilson Engineers to evaluate grit removal technologies. Independent testing revealed that 79% of influent grit was larger than 300 microns, but a system designed for 300-micron removal would only remove 27% of grit when settling velocity was considered. A design targeting 106-micron Sand Equivalent Size would capture 99% of influent grit. The influent grit testing confirmed that the HeadCell® system with a 106-micron design would provide the solution the Airport WRF needed. 

Located adjacent to a busy municipal airport, the plant had limited space for a new headworks grit removal system. Given decades of experience struggling with unchecked grit, the Airport WRF wanted a low-maintenance separation system with minimal moving parts and a proven track record of fine-grit removal performance. 

 

The Solution

Wilson Engineers evaluated aerated grit basins, mechanically induced vortex systems, and stacked tray grit separation. They determined that the HeadCell®, a stacked tray grit removal system engineered by Hydro International, was the best solution. The HeadCell® has no moving parts, and its stacked tray design provides increased surface area in a very small footprint. With nearly 1,000 installed units worldwide, HeadCell® offers decades of independently verified performance. 

In the summer of 2018, Mortensen Construction installed an Advanced Grit Management® system consisting of HeadCell®, TeaCup®, and Grit Snail® units. This configuration provides total plant protection for peak flows up to 45 MGD (170 MLD), with 95% removal of grit 106 microns and larger at peak flows and 95% removal of grit 75 microns and larger at average flows. After start-up, the new system’s performance was independently measured on-site, and the results exceeded expectations. 

 

The Outcome

The new grit removal system transformed operations at Chandler Airport WRF. It eliminated costly grit cleanouts, protected downstream equipment, reduced energy consumption, and extended equipment life and reliability. By investing in a proven solution, Chandler resolved a decades-long challenge and secured sustainable, efficient wastewater treatment for a rapidly growing community. 

 

Learn more 

  • See the latest generation of the TeaCup®, the OpTeaCup®