The congregation of Hosanna! Lutheran Church in St. Charles, Ill., had outgrown its facility and was building a new 40,000-square-foot church with offices, library, nursery, preschool and youth classrooms, a multi- purpose room, and kitchen. The project required a substantial septic system, so the building committee hired Dale and Henry Warfel of Warfel’s Multi-Flo to design and install it.
Warfel, who maintained the old church’s onsite system, faced a familiar challenge: churches are notorious for their unpredictable and erratic flows. To determine the hydraulic flow, Warfel took the maximum capacity of every room, including those to be built as future additions. The kitchen was to be used only for reheating food, so high-strength wastes were not an issue. Warfel’s design incorporated four aerobic treatment units, a lift station, and a 56,250-square-foot drainfield.
Site conditions
The church owned 19.39 acres in rural St. Charles. Soils in the former tree/shrub nursery are silty clay loam with the water table within 42 inches of grade. Inappropriate soils, neighboring potable wells, swales and a stormwater retention pond, and property lines to the south and east restricted the drainfield to one location.
System components
Kane County doesn’t require a professional engineer to design systems or sign off on the plans as long as the installer is licensed. Warfel designed the system to handle 6,000 gpd. Its major components are:
• 4,500-gallon monolithic concrete septic tank with standard 4-inch baffle from Welch Brothers Inc., Elgin, Ill.
• Four M-2000A Nayadic aerobic treatment units (ATU) from Consolidated Treatment Systems Inc., Franklin, Ohio.
• 72-inch diameter, 12-foot deep concrete lift station from Welch Brothers.
• 850 Quick4 Equalizer 36 chambers from Infiltrator Systems Inc., Old Saybrook, Conn.
• 68 Quick4 Equalizer 36 Multi-Port end caps.
System operation
Sewage from the washrooms and gray water from the kitchen gravity flow through a single 6-inch PVC pipe to the septic tank. Flowing out the baffle, the liquid runs to a distribution box that feeds all four ATUs simultaneously. Each fiberglass unit holds 2,000 gallons, but processes 1,500 gallons in 24 hours.
The Nayadic treatment system uses suspended growth and fixed film in a two-chamber hopper- bottom tank. Each unit has an air compressor housed in a tub above it. Wastewater is discharged to the inner aeration reactor. Air, pumped into the bottom of the chamber through a disc plate diffuser, creates a venturi effect as it rises in an 8-inch draft tube. The tube ensures continuous and complete mixing of oxygen with the wastewater, enabling aerobic organisms to grow and digest the nutrients.
The inner chamber also creates a quiet zone that allows digested solids to settle to the bottom, then be returned to the aeration compartment. Treated liquid flows slowly up the clarifier and over an effluent weir that extends 360 degrees around the tank. The weir enhances settling of solids by reducing the hydraulic velocity through the clarifier, thus damping the effects of hydraulic surges. A scum baffle inside the weir prevents floating solids from passing.
Effluent, collecting in the clarifier’s outer trough, is discharged through a 4-inch pipe to a distribution box. It flows 250 feet by gravity to the lift station, where dual alternating Hydromatic high-head pumps raise the liquid five feet before sending it 200 feet to the twin absorption beds. Each drainfield has its own pump. Effluent quality is 6 mg/l BOD and 7 mg/l TSS.
Installation
Warfel and his four men had three weeks to install the system before the parking lots were paved. “We were racing against winter,” he says. “As we prepared to run pipes beneath the driveways to the lift station, we discovered a three-foot storm sewer for the parking lot drain in our way. Our elevations took us right through the middle of it.”
Some investigation revealed that the building contractor had lowered the building pad 12 inches without thinking how that affected the septic system. Warfel reshot his elevations and tunneled under the storm sewer. The crew set the septic tank with its two risers at the inlet and outlet in one day, and the ATUs the next.
“I chose Nayadics because we were jammed in next to the driveway and needed compact units,” says Warfel. “Their inverted cone design requires a smaller area at the bottom of the excavation, which was advantageous because of the site’s water table.”
The lift station is sandwiched between the drainfield to the south and the massive stormwater retention pond and swale area to the north and west. When the crew began excavating the lift station pit, they hit a natural spring at the 12-foot mark, and the hole flooded. Warfel ran 2-inch discharge pumps that sent the water to the pond while the workers set the lift station.
“This was a touchy area,” Warfel says. “The southeast corner had the only acceptable soil for the drainfield, so the engineers curved the pond around it. That meant we couldn’t set the lift station too close to the pond. The only place it could go was 10 feet from the east lot line.” Two-inch Schedule 40 pipe connected the lift station to the drainfield header lines.
Scott Ross from Infiltrator Systems Inc. arrived to help install the chambers. Each drainfield has 425 chambers in 100-foot lines on 9-foot centers. The drainfield footprint is 250 by 225 feet. One day’s work saw the first drainfield installed, inspected, and backfilled. That night, three inches of rain fell, and the team had to wait a week to install the second absorption bed. The drainfields were covered with 12 inches of backfill and planted with grass, and became part of the children’s baseball diamond.
Maintenance
Warfel’s Multi-Flo is the maintenance provider. Twice-a-year inspections include checking the air compressors to make sure they are putting out the proper amount of air, checking the diffusers for clogging, and checking the effluent quality on the weir. An alarm system with audio-visual alerts signals a loss of air supply or high water level in the ATUs. The septic tank is pumped annually.
