Draining the Swamp: Pipeline Replacement Project Takes on Dewatering Challenges

Michigan crew digs trenches in tough terrain to address infiltration.

Draining the Swamp: Pipeline Replacement Project Takes on Dewatering Challenges

Crews from Kamminga & Roodvoets excavated swampland, replaced it with compacted sand and set up a wellpoint system before excavation for the project could begin.

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While the sewer infrastructure of Bath Charter Township, Michigan, deteriorated 20 feet under a swamp, workers manually operated a lift station to stave off downstream overflows during heavy rains. It was an unsustainable situation, and the only way construction company Kamminga & Roodvoets could fix it was to dig through the swamp.

Township officials knew they had an infiltration problem on their hands, as concrete pipes and manholes were failing and allowing stormwater into the sanitary sewer system. But the area’s extraordinarily challenging terrain meant fixing the problem was no small feat for the Grand Rapids-based K&R.

In the project completed last June, K&R worked with Bath and the Southern Clinton County Municipal Utilities Authority on a $2.6 million endeavor to prevent downstream overflows. It included building an equalization basin for overflow storage using thermoplastic pipe that takes on stormwater automatically when the lift station is overwhelmed. The project also called for the revitalization of a lift station, elimination of another lift station, replacement of failing concrete pipe and installation of composite manhole covers manufactured by U.S. Composite Pipe to further prevent infiltration.

The authority was established back in 1976 as a Michigan Municipal Corp. serving the townships of Bath, DeWitt and Watertown, along with the city of DeWitt. The authority owns, operates and maintains a 5 mgd wastewater treatment plant that discharges into the Looking Glass River in Clinton County. It also owns 51 lift stations, more than 30 miles of force mains and more than 135 miles of sewer collection pipes.

Overcoming challenges

To create the system’s new equalization basin, nearly 2,200 feet of 60-inch SaniTite HP pipe made by Advanced Drainage Systems was buried at depths ranging from 18 to 23 feet in swampland. Capable of holding 540,000 gallons, it is large enough to provide sufficient storage volume to prevent sewage backup, and it also allowed for the elimination of an upstream lift station.

The biggest hurdle K&R dealt with on the project was poor field conditions, says Austin Graham, project manager.

“For the most part, the field where we installed the 60-inch triple-wall pipe was in areas covered with water for a good portion of the year,” he says. “It’s a swamp — a mucky area where you have the opportunity to work in that condition just a few months out of the year. There’s standing water there almost all the time.” 

Once the crew started excavating, it discovered that the existing soil conditions weren’t suitable for dewatering. “During a portion of the sewer installation, we needed to remove the spoils and import sand to the proposed trench,” Graham says. “Once suitable soils were installed, we could then install the wellpoint systems to properly dewater the trench.”

Having been forced to set up the wellpoint system for trenching in the new compacted sand, the crew wasn’t finishing as many feet of pipe per day as K&R had anticipated. “We knew we needed an extra crew to work on the lift station portion of the work while this crew focused on the pipe installation.”

The extra crew had been doing other sanitary work on the project, and bringing it in helped K&R gain back some of its lost time. “We have our foreman, crane operator, backfill operator, loader operator and three laborers,” Graham says. “In total, we typically have seven on a full crew.”

Project details

Even though Bath’s Lift Station 203 was failing and undersized, the project bid called for its use and for the elimination of Lift Station 216. The flows from Lift Station 216 would be rerouted to Lift Station 203.

The key to accomplishing this was the equalization basin, which was both economically and structurally vital to the success of the project. Replacing the corroding sewer with large-diameter, corrosion-resistant sewer pipe and creating the basin reduced the load on the lift station from increased flows that happen during large rainstorms.

Since the K&R crew had to do significant preparation work on the difficult site soils, its previous experience using SaniTite HP pipe was helpful. “We basically had to build a trench by backfilling the excavation with sand and then laying in the pipe,” Graham says. “It helped that we were familiar with the pipe and that it was manageable.”

For the project, the crew used 48- and 60-inch-diameter pipe, which is built with a triple-wall construction and watertight joints. According to Advanced Drainage Systems, SaniTite HP pipe’s stiffness and beam strength minimizes deflection and enhances long-term performance. It meets ASTM F2764 while exceeding the requirements of ASTM D3212 for watertightness with dual gaskets and a banded reinforced bell.

Another important factor for this project was the pipe’s tight tolerance and double-gasketed connection, which provides protection from the surrounding soil and groundwater. Because of the extended time sewage would be stored in the equalization basin, the plan required the system to be highly resistant to the naturally occurring corrosive hydrogen sulfide gas. The existing pipeline was failing due to hydrogen sulfide that had corroded the concrete pipe, and the township didn’t want that situation to reoccur.

According to Plastics Pipe Institute, the engineering-grade polypropylene resin used to make the pipe is highly resistant to sulfide gas and the concentrations of sulfuric acid found in a sanitary sewer. Its technical report, TR-19 Thermoplastic Piping for the Transport of Chemicals, contains information on thermoplastic’s resistance to various concentrations of sulfuric acid and other chemicals.

Additionally, the SaniTite HP pipe is designed to last in excess of 100 years, according to Advanced Drainage Systems.

“We use Advanced Drainage Systems plenty, all the way up to 36 inches,” Graham says. “But this is the first time we used the SaniTite HP triple wall up to 60 inches. We felt confident we would be able to take on a challenge like this, given the tough field conditions, just by having the general familiarity of knowing what we need to do for installing ADS single-wall and double-wall pipe. That’s what gave us the confidence to think we could take on a challenge such as this.”


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