A Michigan town’s modern wastewater system renews the once-polluted Raisin River.
Eighty years ago, Richard Jackson walked down a dirt path from his parent’s house in Palmyra, Mich., to the Raisin River. He fished for rock bass and northern pike, and sometimes swam in the chilly waters. This was long ago, before the days of indoor plumbing, and back when you could still plunge your face in the icy flow and guzzle a draft without concern for the water’s purity. “Nowadays you wouldn’t even think of it,” Jackson says.
Amidst the fields of wheat and stands of apple trees, the Village of Palmyra looks like a bucolic painting. Nothing in the scenery suggests environmental problems except occasionally the odor. It started in the 1930s when the town grew with new industry, mills, bars and feed stores. “People got a little money and added indoor plumbing,” explains Jackson. “They got rid of the outhouses and installed flush toilets.” The problem was that without a sewage system, the only place to flush those toilets was down the storm sewers and into the river. The river quickly became a cesspool. And on a warm summer night, Palmyra was a very smelly place.
Fortunately, Jackson, who is now the Township Clerk, has lived long enough to see the first signs of health returning to his childhood waterway. Thanks to clever engineering, combining small-diameter, shallow sewer mains with precast concrete septic tanks, this year Palmyra installed a modern wastewater disposal system – something the poor rural community has tried to afford for nearly three decades.
Designing an affordable system
It was 30 years ago that the Department of Environmental Quality cited Palmyra for polluting the Raisin River and the water table. Household effluent not only drained into the river, but also gray water from washing machines and kitchen sinks spilled into sandy pits for percolation, sometimes within a few feet of the well head. Neither the Raisin River nor the aquifer had potable water in Palmyra, and the contaminants were leaching downstream to neighboring communities. Everyone understood the problem, but no one could figure out how to pay for a solution.
That is until Lenawee County Drain Commissioner Steve May and the engineers of Progressive A.E. in Grand Rapids, Mich., an engineering and architectural firm, put their heads together to come up with a solution. Instead of building a huge gravity-fed sewer system with pump stations and large-diameter pipe buried 3 yards or more below the surface, the engineers and architects at Progressive A.E. designed a public-private hybrid. They combined septic tanks – the same tanks used in private systems – with a municipal main and treatment plant.
Each house would have its own precast concrete septic tank. The tanks would include two compartments with a screen to separate solids and fluids. Since only fluids would spill into the sewer main, the largest pipe needed was just 6 inches in diameter. This meant that contractors could bore sections of pipe under streets and through intersections instead of digging trenches throughout the village. In place of expensive grinder pumps and lift stations, the system included several small effluent pumps. With primary treatment on each property, the central treatment plant could be much smaller. The bottom line: “We saved about 50 percent of the total cost,” May says.
Nevertheless, the system did not come free. “We worked almost three years to arrange the bonds and financing,” May says. “The township would have to pay the loans back over 20 years, so we wanted to make sure the system would last at least that long.” The engineers reviewed the options and chose precast concrete tanks over the alternatives of plastic and fiberglass because precast concrete afforded the best combination of low cost and durability.
As a precaution, the engineers specified sulphate-resistant concrete, given the slight potential for sulphate-rich soils. Once they knew they had a durable solution, one final consideration came with long-term maintenance. Anyone who has lived with a private sewage disposal system knows that every few years, you have to pump sludge out of even the best septic tank. To provide Palmyra with a state-of-the-art system, the engineers worked with the precast concrete manufacturer to make a few modifications.
Building a better tank
Dan Wagner owns Milan Vault, a family-owned precast concrete manufacturing company located in Milan, Mich., less than 50 miles northeast of Palmyra. The commissioners of Lenawee County were delighted to work with a local precaster because managing the delivery of several hundred tanks to scattered sites in coordination with homeowners and their selected contractors could easily become a logistical nightmare. A company within the county and close to the community could handle the job more effectively. Besides, “We like to keep our money close to home,” May says.
Since the county would provide periodic maintenance of the tanks, May wanted to ensure that the tanks were easily accessible. In cooperation with the engineers of Progressive A.E., Wagner modified his standard septic tank design to include an 8-inch, Standard Dimensional Ratio 35 PVC coupler. Into this gasketed sewer fitting, an installer would add an 8-inch PVC standpipe up to grade level, making it easy to uncap the standpipe and drop a hose into the tank for service.
Although most of the tanks would sit only 24 inches below grade, a few installations required deeper burial. For these, Milan Vault included additional reinforcing steel and structural synthetic fibers. These tanks were installed for homes with bathrooms in the basement. “The county didn’t want to make people abandon their finished basements,” says Wagner.
Wagner sees irony in using sulfate-resistant concrete to make Palmyra’s septic tanks, given the additive used to achieve this mix derives from a waste product of steel manufacturing. “Right here in Detroit, capital of the auto industry, we use a lot of steel and they skim calcified limestone from smelting buckets; we buy it and use it to make sulfate-resistant concrete,” Wagner says. “One waste product is used to help deal with another.” All together, Wagner’s Milan Vault supplied Palmyra Township with 167 1,000-gallon septic tanks; 45 1,500-gallon tanks; and five 2,000-gallon tanks. The largest tanks were for businesses and duplexes. Milan Vault delivered every tank to an individual homeowner and contractor for installation.
Getting the job done
A Palmyra homeowner could hire any qualified utility contractor to install the septic tank, and many contractors participated, but Glen Sliker of Sliker Excavating handled 95 of the 217 installations. “Every single one was different,” says Sliker, who learned a lot of local history through his interaction with neighbors.
Peeling away the layers of time with his excavator, Sliker could see how people used to handle their wastewater. “Most had a 3-foot-diameter culvert pipe stood on end in the ground with a cap over the top as a septic tank. Some used burial vaults. Water from the toilets would go into this holding tank and then spill over into a pipe plumbed straight into the storm sewer. People living close to the river had no septic tank at all, just a pipe straight into the water,” Sliker says.
Replacing the historic sewage system involved hauling out the old tank, excavating for the new one and then setting it in place, level and true. Then came the tricky part: connecting the existing sewer to the new tank. Many of the houses had old clay or cast iron pipe that needed replacement.
“In most cases, this didn’t entail just one sewer line. Not all the pipes went into the old septic tank. People used to have a soap trap for the sink and bath water,” Sliker says. Because the harsh soaps used for laundry and kitchen cleanup would inhibit the bacterial action that breaks down solids in a septic system, people plumbed their soapy water to a separate brick cistern.
“They used brick so the water would seep into the ground,” Sliker says. With shallow wells in the area and sandy soils, this was a recipe for well water contamination. “Nowadays you can’t drink any of the well water in Palmyra. Some of it comes out black,” Sliker says.
For this reason, not everyone supported the sewer system retrofit. “A lot of people said what we needed first was water, not sewer,” Jackson says. But with the Department of Environmental Quality threatening the village with fines approaching $25,000 a day, “There wasn’t much of a choice,” he says.
Nevertheless, as the sultry days of summer faded into early autumn and the last tanks come into service, Jackson walks down to the river to test the air. “It’s clean now,” he says. Thanks to resourceful engineering and reliable, durable and cost-effective precast concrete septic tanks, Jackson can once again idle by the Raisin River enjoying unspoiled memories.