Collapsing Metal Waterfront Tank Has to Go

Installer Greg Simac, regulators and suppliers work together for a seamless emergency tank replacement project at a busy Wisconsin resort.
Collapsing Metal Waterfront Tank Has to Go
The Kobelco SK220LC excavator and tanks barely fit between the cabin and tree.

Interested in Septic Tanks?

Get Septic Tanks articles, news and videos right in your inbox! Sign up now.

Septic Tanks + Get Alerts

Corrosion caused the crown of a 7,500-gallon steel pump tank to slowly cave in at the Afterglow Lake Resort in Phelps, Wisconsin. The tank, part of the facility’s 32-year-old onsite system, was 40 feet from the water.

The 7.5 hp pump leaked and took 15 hours to lower the liquid in the tank. “It was impossible to replace the pump, which weighed hundreds of pounds and was 10 feet below grade in the unstable tank,” says Greg Simac of Simac’s Plumbing in Eagle River. “The longer the pump ran, the more water leaked onto the crown.”

The weight of wet, dense clay pressing on the tank’s top and sides further weakened it.

With the tank’s collapse imminent and the 33-bedroom resort at full capacity, Simac swung into emergency mode. Facilitated by the cooperation of manufacturers and regulators, he coordinated the logistics in a week and replaced the tank without disturbing the guests’ routines.


Metal septic and holding tanks were common in northern and central Wisconsin and along the Lake Michigan shoreline from the 1970s to 1990s. Although steel tanks are still approved under Wisconsin Administrative Code, modern contractors will not install them given their history of corrosion. When such tanks are located through sanitary surveys and mandatory onsite inspections, they are replaced in accordance with the local authority’s process.

An upgrade to the onsite system in 1983 had replaced most of the cabins’ individual 500-gallon steel septic tanks with 1,500-gallon concrete units. The contractor ran 4-inch Schedule 40 from each tank to a 5-inch discharge line. It connected to a wye at the 8-inch inlet of the 34- by 6-foot-diameter pump tank. From the opposite end of the resort, two additional cabin lines hooked to a 5-inch pipe that ran from the back of the tank to the wye.

The pump pushed 61 feet of head 1,000 feet through a 4-inch Schedule 40 force main to a 100- by 41-foot-wide stone-and-pipe mound. When the pump labored to lower the level of the tank, Simac assumed the drainfield had failed. However, an electrician from Rogers Control discovered the pump was no longer running at full capacity.

“We shut off the pump and called Mike Oberg of Mike’s Septic Service, who pumped the tank twice while we lined up replacement parts,” says Simac. The mound was full, but dried in two days after emptying the pump tank.

Order of attack

The Tuesday before the repair, Simac’s called Sam Grulke of nearby First Supply, who sized the on-demand alternating replacement pumps. “None were in stock, so Sam called the Xylem factory in New York and they put two 2 hp Goulds pumps on a freight truck Thursday morning,” says Simac. He also ordered a Xylem CentriPro SES duplex control panel.

Simac then called Vilas County Zoning and requested permission to make the emergency repair without waiting for a permit. They approved, as did the state Department of Safety and Professional Services. The permit came later.

Simac also called Chad Johnson, owner of Concrete Products in Rhinelander. “I wanted the pumps on a rail system, but Chad didn’t have time to pour a lid with two adjacent risers,” says Simac. He ordered what was in stock:

  • 800-gallon septic tank with Polylok PL-525 effluent filter
  • 2,000-gallon pump tank
  • 2,000-gallon overflow tank to handle power or pump failures forone day

The ambient July temperature was hot enough to soften the tar between the tanks and lids. Workers at the yard popped the lids and inserted paper to make their removal easier. They also wet-prepped the tanks with tar to counteract high groundwater.

Needing the largest excavator in the county, Simac hired Tom Collins of Collins Excavating Grading and his Kobelco SK220LC machine.


Simac originally planned the staging area on an old access road to the resort. It meant driving equipment around the shoreline, navigating past rental kayaks and canoes, a campfire pit with half-log benches, and crossing the bathing beach.

On Thursday, Simac and Collins walked the site. Neither liked the proposed scenic route. The direct path from the main road to the lake was obstructed by a few trees and narrowed significantly between a cabin and a red pine. Collins measured the space and announced he had just enough clearance for his 14-foot-wide machine.

Galvanized waterlines buried 4 feet deep crossed the path to the lake. Simac covered those areas with plywood sheets to distribute the weight of the tank truck and excavator. Over the weekend, the resort owner cut down the marked trees, including a mature maple at the corner of the pump tank. Johnson also delivered the tanks, off-loading them 40 feet from the work site.

Because the shore sloped 20 degrees toward the lake, Collins helped Simac erect a silt fence on Monday. They also brought a 2-inch and 3-inch trash pump to dewater the excavation, and hay bales to filter the discharge.

Dig day

The sewage pumps arrived Tuesday at 8:30 a.m., along with Johnson and Oberg, who pumped the tank. Resort guests were asked not to run water or flush toilets for two hours. “The excavation site was near a large cabin with a 50-foot-long deck,” says Simac. “We had about 60 enthusiastic guests watching all day.”

At 9 o’clock Collins started the excavator, and everyone held their collective breath as he maneuvered it through the gap. “A soda cracker wouldn’t have fit on either side of the body,” says Simac. “As heavy as the clay was, the machine and tank truck still left 6-inch-deep depressions. I don’t think we would have reached the site had there been high groundwater.”

Collins built a level work platform from clay scrapped off the top and sides of the 5-foot-deep tank. “We could see it buckling as he dug,” says Simac, who directed Collins and watched that he didn’t damage piping.

When the whole tank was exposed, its inlet was level with the surface of the lake. “If the heavy clay hadn’t acted like a dam, the hole would have been full of water,” says Simac.

Although rotten, the tank refused to come out in one piece. Collins ripped it in half and extracted the sections. He leveled the floor of the hole with the bucket, then Simac finished with a shovel, a length of pipe and a level.

Cheering section

Spectators cheered as the excavator emerged through the gap carrying the septic tank without its lid. “We removed the lids to ensure the machine would be able to lift the tanks,” says Simac. Once Collins set them in the hole, the soil was soft and wet enough for them to find level ground.

Simac used 5- to 4-inch fittings to downsize the discharge lines, then ran a standard 4-inch pipe to the inlet of the septic tank. He set the pumps on the bottom of the tank and direct-plumbed them straight up the 24-inch riser. The resort was back in business.

The guests continued to celebrate as tanks went in the ground. Simac also installed a clean-out at the inlet. The county inspected the installation before Collins backfilled the hole.

Meanwhile, the Rogers Control electrician wired the pumps and control panel, then Simac programmed it to dose the drainfield with 660 gallons. “The emergency repair was a massive undertaking,” he says. “What we never imagined was that it would become one of the most unusual events guests will ever see at a northwoods resort.”


Comments on this site are submitted by users and are not endorsed by nor do they reflect the views or opinions of COLE Publishing, Inc. Comments are moderated before being posted.