A Busy Minnesota Summer Camp Demands a Creative Onsite Solution

Flow equalization and a series of big tanks is the key to handling occasional spikes in usage at YMCA Camp Manitou

A Busy Minnesota Summer Camp Demands a Creative Onsite Solution

The dosing tank chamber at Camp Manitou in Minnesota holds another Schmitz idea. He installs a vertical access pipe and two 45-degree elbows. If a supply line freezes in a harsh Minnesota winter, the elbows create a gentle curve for a technician to feed a jetter hose through.

The YMCA Twin Cities planned to create not just a simple day camp, but a large complex on the shore of a Minnesota lake that would serve children from the Minneapolis and St. Paul metro areas and the city of Rochester.

In partnership with the city and county of Monticello, the YMCA created the Bertram Chain of Lakes Regional Park. It’s 1,200 acres of protected land and lakes west of Monticello and about a 45-minute drive from downtown Minneapolis. All the land is protected and open to the public except for 12 acres on the shore of Long Lake. That’s dedicated to the Camp Manitou day camp.

Of course, the camp has a beach and bathhouses that need wastewater treatment. There is also a swimming pool and splash pad, an office building and an art pavilion. The job of handling the wastewater came to Peter Schmitz, installer, and Bernie Miller, system designer.

Although the construction was new, there were constraints on the site, Miller says. He owns Miller’s Sewage Treatment Solutions in Kimball and designed the YMCA system.

Because of the property’s sandy soils, the state determined the aquifer was sensitive. Systems in sensitive aquifers and with flows greater than 2,500 gpd require nitrogen reduction, but there was no room in the YMCA budget to add nitrogen pretreatment. Miller looked at similar YMCA camps where flows vary considerably depending on the schedule. He determined weekly flows at Camp Manitou would be 9,875 gallons. By including flow equalization in the system, Miller kept the design flow below the 2,500-gpd nitrogen treatment threshold.

“It was kind of a puzzle putting this together. The YMCA really didn’t want to have the drainfield in their ballfield, but they didn’t have any other suitable space,” Miller says.

The system

The system serves three buildings at the camp: the office building and shelter, the bathhouse and the art pavilion.

Wastewater leaves the office building and bathhouse in 4-inch Schedule 40 PVC lines and empties into the first of two 5,000-gallon septic tanks connected in series. Wieser Concrete provided those and the other tanks for the project. These tanks provide initial treatment and settling.

Because of the layout and grades on the property, wastewater from the art pavilion takes a different route. A 4-inch Schedule 40 PVC line moves wastewater from the pavilion into a 1,000-gallon lift station. A Goulds Water Technology, a Xylem brand, PE31 pump sends wastewater 215 feet through a 2-inch Schedule 40 PVC line, and this empties into the 4-inch line just upstream of the first septic tank.

The two septic tanks are separated by 3 feet of Schedule 40 PVC, and wastewater flows by gravity from the first to the second. From the second tank, wastewater flows through a Polylok PL-525 effluent filter with an alarm, and then through 3 feet of Schedule 40 PVC pipe to the 6,000-gallon pump tank.

A pair of Goulds PE41 pumps sends wastewater through 205 feet of 2-inch Schedule 40 pipe that runs under the ballfield. The drainfield is just beyond the outer edge of the field and covers 108 feet by 71 feet.

An Alderon Industries panel runs the pumps. The advantage of this panel is its two settings for time dosing, Miller says. A second float tells the panel that the system is experiencing peak flow, and the panel decreases the time when pumps are off. “This has been something that saved a lot of headaches on the service side over the years,” Miller says. “It can save you that phone call on Sunday from people having an alarm.”

Risers are Orenco Systems Ultra-Rib, and lids are 24-inch insulated Polylok.

The field is split into two zones, with five laterals in each and one distribution box for each zone. Distribution boxes are placed side by side at a high point. Each lateral is set about 4 inches below the one upstream so the entire drainfield is gravity-fed, and one lateral fills completely before the next one.

Laterals are set 7 1/2 feet on center. Each one is made with a piece of 4-inch perforated pipe set on 12 inches of 1 1/2-inch rock. On top of the pipes are another 2 inches of rock, and that is covered with geotextile fabric. Cover soil was placed on top of the fabric.

Equipment Schmitz used for the project included a Cat 312C excavator, Cat D5G dozer, Cat 257D track loader, Cat 950 loader to move the excess dirt, low-boy by Fontaine Trailer to move the equipment and Mack 613 CH tractor to pull them, and a pair of Mack dump trucks to haul rock, a 1988 RD690S and a 1995 CH613.

Easy locating

The area designated for the wastewater system also includes an undeveloped expansion area to accommodate any future growth of the complex.

Children will be playing near the drainfield, so trip hazards were eliminated by burying almost all of the drainfield components. Schmitz put 6-inch sections of rebar in the ground next to the distribution boxes and the clean-outs and about 4 inches below grade. With a locator and the as-built plans, anyone needing to uncover these components should find the job easy, he says.

With Minnesota’s frigid winters, Schmitz makes a special adaptation to lines running out of a pump tank. Instead of connecting the vertical pipe from the pump directly into the horizontal pipe running to the drainfield, he installs a T and adds a run of capped vertical pipe. This joins the T fitting through a pair of 45-degree elbows connected in series. This extra pipe allows a technician to run a jetter hose into the dosing line to remove a clog or clear a frozen spot. The two 45-degree elbows create a gentle curve that’s easier to push a hose through than a 90-degree bend, Schmitz says.

When Schmitz puts his drainfield pipes in the ground, he first installs wooden stakes with saddles that the pipes rest on. These keep the pipes level and removes the need to shovel stone under the pipes.

For spreading the stone he has another tool: a conveyor that attaches to his truck. On a new construction site like Camp Manitou the conveyor is useful. When he’s working at someone’s home, it’s even more useful because stone isn’t dumped on a customer’s grass or driveway, it isn’t scattered over the ground as the system is being installed and technicians aren’t cleaning up dirty stone with a loader bucket.

Ongoing discussions continue about the future of the land. The hundreds of acres around Camp Manitou could be used for other types of activities. An RV park has been mentioned. But whatever comes about, the YMCA camp will be doing its share to protect the quality of the recreational land.


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