New trash rakes meet deadline – despite the pandemic
Automated trash rakes with frequent equipment failures to be replaced by a much more efficient new system – all very carefully scheduled for a fast-track completion ahead of the November to June flood season – and then along comes a pandemic.
For the Multnomah County Drainage District No.1 (MCDD) in Portland, Oregon, who help protect lives and property from flooding, robust pumps and trash rakes are essential, so from what was already a major, time-sensitive equipment upgrade, the all-important deadline suddenly became a challenging journey into the unknown.
MCDD, in conjunction with three other districts, operates and maintains flood management systems for nearly 13,000 acres of land along the Columbia Slough and the lower Columbia River. These systems include: 27 miles of levee, 12 pump stations, and 45 miles of sloughs, streams, and culverts – maintaining the river corridor levee system and vitally removing stormwater, which protects tens of thousands of jobs and residences, hundreds of acres of parks and natural areas, places of cultural and historical significance, and public infrastructure such as Portland International Airport.
One cannot underestimate MCDD’s level of responsibility to keep all the water moving and under control. Since its inception in 1917, there have been five major high-water events, with the most devastating being the flood in 1948 that killed 15 people and destroyed the city of Vanport.
In recent years, during heavy rainstorms and debris accumulation, frequent equipment failures were causing the existing, automated trash rakes at MCDD’s Pump Station #1 to shut down.
Brian Eberhardt, MCDD’s Project Manager said: “With the old rakes at the end of their service life, we had the opportunity to invest in better, looking at how we could improve the performance of the pump station – and have a system that would also allow the debris gates to handle larger items such as trees. We also wanted to have trash rakes designed with quicker self-cleaning that would in turn be easier to maintain.”
Randy Lyons, MCDD’s Operations Manager, added: “We were having to undertake far too much supplemental removal of debris, which for 6 to 8 days of the year meant us having to have a two-man team go out on a barge to collect larger debris with an excavator, which apart from taking up valuable time, also raised health and safety concerns.”
Replacing in kind wasn’t an option when Brian Eberhardt and his MCDD team began looking for a new system with mechanical design firm, Murraysmith, and their Senior Engineer, Austin Rambin. A much bigger mechanism with a larger rake head was required to increase efficiency over the previous units, which had a three-and-a-half-foot rake head. Also, a trash rake that could lift 2,000 lbs or more was needed, versus an existing lifting capacity of 1,250 lbs.
“We spoke to operators in our region and went to see them”, said Austin Rambin from Murraysmith. “These included one at a hydroelectric dam and another at a power generating site. The fact that the Lakeside Muhr trash rake was scalable for our required widths was a big advantage, rather than some manufacturers, who could only provide fixed sizes.”
‘Cleaning time reduced to less than five minutes’
He continued; “MCDD has a very good, experienced team, who certainly know how to maintain and troubleshoot, but when we were considering the design of the system around the rakes, we knew we wanted to improve on the cycle time for cleaning, which for two traversing rakes on a chain system, was taking half an hour. With five Lakeside Muhr stationary Model T-260 Hydronic T Trash Raking Mechanisms, this cleaning time would be reduced to less than five minutes.”
MCDD’s Asset Maintenance Specialist, Josh McNamee, added: “The Lakeside rakes allowed us to achieve our aims by providing the increased redundancy we’d gain from having one rake per bay; also, with fewer moving parts to maintain and less movement. Less wear and tear would reduce operation and maintenance time as well as costs – and lessen the use of our log boom.”
With the support of MCDD’s Operations team, Brian Eberhardt said: “We confidently placed our fast-track order in November 2019 for delivery by the end of June 2020 – and then of course in the spring of 2020, right in the middle of the manufacturing process of our new equipment, COVID-19 hit.”
As we have all experienced during a truly extraordinary time, life changed; working from home – a switch, and not always for the better in how to communicate and coordinate the working day, staff unable to work; and a whole new world of precautions with a sudden urgent regime of new safety protocols to be adhered to – all for very good reason – but not exactly part of a crucial plan for an impending season of potential flooding.
“We needed more manpower to do the same job”, continued Brian Eberhardt. “And with the weather not always being predictable, the pressure was high to somehow still achieve the fast-track delivery and installation dates.”
‘Quick-thinking and clear lines of communication’
Speaking for Lakeside, Dan Widdel, commented: “We were determined to deliver everything as originally scheduled for the June 30th, 2020 deadline – and it is a tribute to all parties pulling together that made it happen. MCDD and Murraysmith are top quality professionals, who kept positive throughout. The huge degree of cooperation and coordination allowed us to work quickly on verifying field dimensions so that long-lead items could be ordered straight away. Quick-thinking and clear lines of communication also enabled us to manufacture the trash rakes to fit the equipment within the existing Pump Station’s structure; match everything up to clean the existing bar racks, and to discharge debris into the existing conveyor system.”
Just in time for the November to May flooding season, the new Lakeside Muhr trash rakes were in place and working by the middle of October 2020.
The Hydronic T trash rakes are constructed in galvanized steel and include hydraulic power units (one HPU for each trash rake). Having five individual trash rakes allows four units to remain in operation if/when one trash rake has to be taken off-line for any reason such as routine maintenance. Usually, the trash rake systems are furnished with completed control panels, but on this occasion, MCDD wanted Lakeside to work with its systems integrator, Industrial Systems, Inc. of Vancouver, Washington, to ensure that the SCADA system would operate and control the new equipment.
The trash rack cleaners are designed to initiate an automatic cleaning cycle based upon a liquid level sensor or via time clock operation. The hydraulically-driven trash raking mechanisms start in a parked position, with the telescoping boom and rake head fully retracted. Upon activation, the telescoping boom moves outward (away from the bar rack) and lowers the rake head downward to the bottom of the bay floor. With the telescoping boom fully extended, the rake head then moves inward into the bar rack for engagement. Once engaged, the telescoping boom raises the rake head to remove captured debris from the bar rack. When the telescoping boom approaches the fully retracted position, debris is removed from the rake head via a wiper blade and discharged into an existing trough, which is then transported to a debris pit, before being removed by an excavator.
‘Protecting downstream properties from flooding has to happen at all costs’
Liz Edgar, Engineer and Construction Lead for MCDD, said: “The installation certainly achieved our goals of reducing maintenance and cleaning times. Protecting downstream properties from flooding has to happen at all costs, so the upgrade has given us a more robust system, with everything moving in the right direction. It’s been a difficult time, but we all pulled together. The MCDD crew was awesome to work with and certainly rose to the challenges.”
Cory Pierce, MCDD Operations Specialist, added: “Overall, the new trash rake is easy to work with, especially when compared to our old system. When we had curveballs, our crew really stepped up and was able to adjust on the fly.”
Randy Lyons, Operations Manager, continued: “Just to add to all the complications of COVID-19, we had staff vacations and smoke from wildfires to try and negotiate.”
Brian Eberhardt concluded: “The creativity and persistence shown by the Operations team did not waver during some very challenging troubleshooting. Hard work, quality of construction, and ingenuity were major factors in the success of this project. Completing in time for the major flood season – despite everything – is a major achievement for our team.”
“Once the rakes were operational, our team worked with Lakeside’s and Muhr’s engineers to dial in controls, to help the system work as efficiently as possible through January 2021. We have now completed our first flood season with the newly installed rakes, and are very pleased with the speed, lifting ability, and level of control made possible with the Lakeside Hydronic T system.”