Eric is a senior project manager at Garver where he serves as the Water and Energy Practice Leader. He specializes in delivering sustainable infrastructure solutions through optimized hydraulic systems and optimized treatment processes. In 2019, Eric was selected for the Water Research Foundation’s 12-person Energy Advisory Committee where he advises the group on energy efficiency and process optimization projects. In 2022, Eric was selected to the AWWA M83 - Energy Management of Pumping and Treatment Processes design manual committee and is the co-author of Chapter 3 – Managing Energy in Pumping Processes, along with Dr. Tom Walksi. Eric is a certified Pump Systems Assessment Professional (PSAP) through the Hydraulics Institute, and he also an instructor in the PSAP course offered through HI. Being PSAP certified allows Eric to set the standard for pump systems assessments and optimization techniques, leading to energy efficient and reliable systems.

Garver was selected to perform Widefield Water and Sanitation District’s (WWSD) Integrated Water and Wastewater Hydraulic Masterplan in November 2019. The community WWSD serves is one of the fastest growing communities in the United States, located just south of Colorado Springs, CO. As one of the initial steps to develop the hydraulic model our client, Garver’s engineers performed due diligence efforts by reviewing existing as-builts for pipelines and pump stations, allowing the hydraulic models to be developed from scratch. In doing so, Garver engineers noticed there were 18 locations in the distribution system, and one location on their main force main, that did not have air release valves at intermediate highpoints in the pipeline profiles.

When air release valves are not properly sized and located at intermediate pipeline highpoints, not only does the headspace of the pipe become “locked” with air at the highpoint, it continues down-gradient for a significant distance. This phenomenon acts as a significantly throttled isolation valve that reduces the cross-sectional area of the pipe, thereby increasing fluid velocity and subsequent headloss. This results in more pumping total head required to maintain an equivalent flow, which translates to more horsepower. An air-locked pipe network steepens the system curve, increases the energy intensity, and increases the probability for a water hammer to occur when the air bubble releases.

Out of the 18 identified in the distribution system pipe network air valve audit analysis, Booster Pump Station No.2 was the most severely air locked and the easiest to remedy since it was in a building and not buried. At this location, there was not an air release valve between the discharge flange of the vertical turbine (VT) pumps and the check valve, nor were there any downstream of the check valve before it went underground. Garver recommended that WWSD operations staff install a $200 combination air valve between the discharge nozzle of both 50-hp, 1,100 gpm, 156 ft VT pump and the check valve. WWSD operations staff informed Garver the pump station flow consistently increased by 900 gpm (81%) after installing the combination air valves on both pumps. Due to the substantial increase in flow, WWSD did not have to install a $2.5M Booster Pump Station No.2 upgrade as soon as originally anticipated. This upgrade that had been earmarked for their fourth quarter of 2020 could now wait until approximately 2023.

Furthermore, this finding convinced WWSD upper management to prioritize an air valve audit for the rest of their distribution system. Doing so would determine if similar findings can be achieved for the 52 other locations that were flagged as a potential air-locked location. If so, this could prevent deploying capital-intensive transmission line and booster upgrade projects already earmarked in the CIP. Prior to these findings, it was believed the high-growth, eastern section portion of the distribution system was serviced by pipes that were too small in diameter, requiring larger or parallel transmission lines and more booster pump stations. In reality, all that was needed were properly installed air valves at intermediate highpoints. However, significant infrastructure and roadways already paved over areas where air valve vaults were needed.

WWSD Engineering and Operations staff re-prioritized capital improvement projects to address this air mitigation project.