An emergency septic tank replacement incorporates multiple 10,000-gallon precast tanks, precast manholes plus an array of pumps, controls and turbines.
By Bridget McCrea
Photos provided by Tim Queior, Camp Precast
With about 800 students in grades pre-K through 12, the Brushton-Moira Central School District (CSD) is in the northern region of New York State not far from the Canadian border. The district recently found the building housing most of its students in need of a new septic system to replace the one that was originally built in 1959.
After completing a building condition survey, the district decided to put a new parking lot over the existing septic system. The school’s wastewater was flowing to a 12,000-gallon septic tank that discharged the water to five different 12-foot-by-50-foot dry wells. Brushton doesn’t have city-wide septic, so the school’s system was private.
Needing additional dry well space to accommodate a new wing, the school tested the system while also making sure it could hold the weight of the new parking lot. During that review and testing phase, the district learned that one of the existing silos feeding the sewage into the leach fields was filled.
“That shouldn’t have been happening,” said Mike Malette, director of facilities for the district. “The more we investigated, the more we realized it was time to update the septic system so that it wouldn’t fail on us during the school year.”
Brushton-Moira CSD contacted the New York Department of Education (DOE), which deemed the septic system replacement as an “emergency” project.
“Even the experts were telling us that our 60-plus-year-old system would fail any day,” Malette said. “And you can’t run a school without a septic system.”
Wanted: Durability and Longevity
After coming up with a few designs that were rejected by the New York State Department of Environmental Conservation (DEC), the district began working with Eric Murdock, P.E., of ONSITE Engineering to design one that would meet the school’s current and future needs and also would align with all environmental standards.
The surrounding soils presented an interesting challenge in that the drainage is actually “too good,” according to Malette, and tends to percolate too fast. That raises the odds of the sewage potentially getting into the water table, although this has never occurred.
“We didn’t want to take any chances,” Malette said, “so we started looking at systems that would clean the water before it got into the leach field.”
“The site is comprised of rapidly percolating soil, so we had to comply with the DEC’s nitrogen guidelines,” Murdock said.
Anytime the soils move water faster than a rate of one minute per inch in New York, it’s considered “fast.” Even if the organic content of the wastewater is removed, the resultant water may still contain nitrogen. Because of this, septic systems in these areas have to incorporate a nitrogen-reducing compound.
Working with Murdock, the district designed a “mini sewage plant” that incorporated a number of different components plus precast concrete tanks and manholes. Murdock said that at one point fiberglass was viewed as a potential option for the tank construction but was removed from the list fairly quickly due to cost. That left precast as the material of choice.
Malette said he was all in favor of precast concrete for the tank materials on this project.
“I’m pretty old school and a firm believer in using concrete for these types of projects due to its strength and durability,” he said. “The main drop tank is situated near the parking lot and takes a lot of abuse. I’m not sure if fiberglass would have withstood all of that wear and tear.”
A Mini Septic System
After meeting with the DEC, Murdock gathered the requirements and then used that information to develop a set of drawings that the department ultimately approved. The 10,000-gallon per day (GPD) system would include four 10,000-gallon precast concrete septic tanks, two 2,500-gallon single-compartment lift stations and multiple White Knight WK-200 Microbial lnoculator Generator towers (to meet the DEC’s nitrogen-removal requirement).
The system also included numerous effluent filters and recirculation pumps, four precast manholes, air pumps, turbine fans and a control panel, among other components. Tim Queior, New York State sales rep for Camp Precast in Milton, Vt., said the company got involved with the project after learning about the RFP and successfully winning the bid for the precast portion of the septic system.
During the design phase, the precaster helped determine which tank sizes and shapes would work best for the application, knowing that the pieces would have to travel over the road about 2 1/2 hours to get from the plant to the school site. Once on-site, the tanks, manholes and other pieces would be installed by TJ Fiacco Construction of Norwood, N.Y.
Queior was on-site to handle all of the rigging and to provide direction and support throughout the project. While the undertaking was fairly straightforward for Camp Precast, there were some unique transportation and site challenges that had to be addressed.
“We had to make sure the crane was right and the site was prepared, knowing that all of the tanks were going to be set in one day,” Queior said. “We staged trailers, stacked them and got out of there because we wanted to cut the crane cost down to just one day’s work rather than two.”
The precast pieces also required special care during transport. The tank’s upper sections, for example, had to be placed on two fairly narrow walls that would be riding on the trailer across potentially bumpy, uneven road surfaces. To cushion them and avoid possible damage to the tanks, the precaster placed very dense foam under each section.
“We don’t ever like our products to be sitting tight against the trailer decks,” Queior said. “And while some trailers do have a light camber to them, each one is a bit different and we didn’t want to take any chances.”
The foam did the trick in this specific instance.
“It performed like nothing I’ve ever seen,” he said. “The precast pieces all arrived onsite in perfect condition and ready to be set in place.”
The project went smoothly, and the school district is pleased with the outcome, having been able to both replace its aging septic system and put a new one in place tha accommodates future growth.
“Everything was well thought out, and installation day went like clockwork,” said Queior, who credits the district’s choice of precast with helping to make that happen so quickly.
The material choice also lends itself to long-term success due to the durability and watertight qualities that precast concrete is known for.
“The project pictures tell a pretty good tale of how everything lined up so well,” he said. “Now, it’s just a matter of servicing and maintaining the system from the various ports of entry that we included for all of the ‘bug eater’ devices. It’s just that easy.”
ONSITE Engineering services the system four times a year, and Murdock said the setup has been performing well since it was put in place. The treatment component encompasses aerators that were installed on four of the tanks, and ONSITE services those treatment components and also handles the required compliance sampling.
“That’s all been going well since installation,” Murdock said.
Because the system handles more than 1,000 gallons of liquid per day, the DEC requires inspections by its regulators. It also requires ONSITE to log all of its analytical results in a national database on a quarterly basis. During their onsite visits, technicians check the fans, pumps, control panels and air pumps. They also submit water quality samples to ensure compliance with subsurface discharge permit limits.
“We’ve been doing that as required, and so far the system has performed far above our expectations in terms of analytical results,” said Murdock, who added that there also is plenty of room to scale up as needed. “The system is sized so that it’s got a much greater treatment capacity than it’s being used for at this point.”
Malette also is pleased with the results and happy that Brushton-Moira CSD now has a modern septic system that’s operating well and no longer in danger of potentially failing and/or leaching nitrogen into the area groundwater. He said the project went well and that TJ Fiacco Construction went out of its way to accommodate the district’s needs and get the job done as quickly as possible. In fact, Malette said all of the organizations involved with this project pulled their respective weight and contributed to its overall success.
“Everyone worked as a team,” said Malette, who currently is working with the contractor on a new district project. “The biggest challenge on this one was coming up with the original plans, but once we did — and once those plans were approved by the DEC — the rest of the job went very smoothly. It exceeded our expectations and is working very well for us.”
Bridget McCrea is a freelance writer who covers manufacturing, industry and technology. She is a winner of the Florida Magazine Association’s Gold Award for best trade-technical feature statewide.
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