By Ivan Raconteur
LESTER PRAIRIE, MN When we turn on a tap, we expect the water to flow, but we may not give much thought to how that happens.
In Lester Prairie, as in other cities, there are some dedicated individuals who do give it thought, and work hard behind the scenes to make sure that the water keeps flowing.
In order to get a better understanding of this process, I spent Thursday night riding with Lester Prairie’s water operator Lee Ortloff.
It was approaching midnight as I drove through town. The lights were out in many of the houses, and the streets were deserted.
I met Ortloff at the city maintenance building. He answered a few questions and then explained the mission ahead.
It was time for the spring hydrant flushing.
Because it does not have a water treatment facility, the City of Lester Prairie flushes its fire hydrants three times each year.
Ortloff explained that the process is used to flush the sediment out of the city’s drinking water system. It also removes stale water from some of the dead ends in the distribution system.
The flushing process also allows city staff to inspect hydrants and make sure that they are working, which is critical in the event of a fire.
Ortloff said Lester Prairie is the only city he is aware of that flushes its hydrants at night.
He said maintenance supervisor Greg Mueller started the system several years ago and it works well for Lester Prairie. Overnight is the time when the fewest people are using the system, Ortloff explained, and because there is little traffic, the city staff is able to work quickly and get the entire system flushed in one night.
It takes six to eight hours to completely flush the system.
Shortly after midnight, city maintenance worker Adam Birkholz and Maintenance Supervisor Greg Mueller arrived.
There was no discussion because they all knew the plan from long practice.
They begin the hydrant flushing near the water tower, where the pressure is strongest, and work outward.
Birkholz started on the north side of town and Mueller on the south. Ortloff began in the East Park Estates development.
After pausing to fill up his travel mug with coffee, Ortloff led the way to one of the city trucks and we were off.
Our first stop was the water tower.
Ortloff explained that the maximum depth in the tower was 32 feet. A couple of hours earlier, he had filled the tower to 31.5 feet in preparation for the flushing.
“We are going to use a lot of water tonight,” he said. The tower holds 300,000 gallons of water, and Ortloff said it takes about 450,000 gallons to flush the system properly.
He turned the tower back on and we were off to the well house in the city park. Ortloff increased the rate of the variable speed pumps to about 450 gallons per minute to keep up with the expected demand.
From there, we went to East Park Estates and began flushing hydrants.
The hydrant on the extreme eastern end of the development is at the end of one of the longest 12-inch water mains in the city, Ortloff explained, and he let this hydrant run longer than the others because of the time required to clear such a long pipe.
That water main, like other newer ones in the city, is PVC pipe. The older ones are ductile iron.
The process for flushing hydrants is an active one.
Ortloff would jump out of the truck, open the cap on the hydrant, and crank open the valve, sending a cascade of water shooting out across the street. Ortloff paid close attention to the appearance and the smell of the water.
The water at many of the hydrants turned as dark as the coffee in Ortloff’s mug as the pressure churned up the sediment.
“You see why we have to do this?” Ortloff asked.
He let the water run until he was sure it was running clear before he closed the hydrant and jumped back in the truck to head for the next hydrant.
Like many cities, Lester Prairie has a number of dead ends in its water distribution system.
At one of these, the stale smell of stagnant water drifted into the night air as soon as Ortloff opened the valve. He let the water run until the stale smell was replaced by the smell of chlorine, indicating that the water in the line had been refreshed.
The process continued throughout the night until all 93 of Lester Prairie’s hydrants had been flushed.
The process is repeated three times each year. The first is in the spring, the second takes place in July, and the third is done as late as possible in the fall.
Maintaining water quality
Lester Prairie’s water contains high levels of iron and manganese, Ortloff said, but not high enough to require the city to have a treatment plant.
If the city did have a treatment plant, the frequent flushing would not be required, he explained.
The city council recently considered building a water treatment facility using 20 percent grant money combined with low-interest financing, but chose not to pursue the project at this time due to the economic conditions.
The iron and manganese are not health hazards, but they do affect the palatability of the water for residents.
It is the iron accumulating in the pipes that is responsible for “brown water” complaints, Ortloff explained.
Lester Prairie has three water supply wells that pump directly into the distribution system (with the addition of chlorine and fluoride). Wells two and four are 180-feet deep, and well number three is 295-feet deep.
The water does not all flow through the water tower as some people believe, Ortloff explained. The tower is used to maintain water pressure (60 to 62 pounds per square inch) and to create capacity for the system.
The Federal Safe Drinking Water Act is the principle regulation governing public water systems in Minnesota, Ortloff said.
It defines what a system is, sets drinking water quality standards, institutes water sampling and survey schedules, and establishes requirements for source water protection and operator certification.
The primary standards protect drinking water quality by limiting levels of specific contaminants that can adversely affect public health.
There are also secondary guidelines regarding contaminants that address cosmetic or aesthetic effects in drinking water, such as taste, odor, or color.
Ortloff explained that hydrant flushing is a necessary part of maintaining water quality.
Flushing velocity needs to be at least 2.5 feet per second to sweep out accumulated material in the pipes.
To maintain water standards, Lester Prairie tests for bacteria, nitrates, arsenic, lead and copper twice each month. Water samples are sent to a certified lab for testing.
The level of fluoride in the water is checked daily, and the level of chlorine is checked weekly.
“There is quite a bit of record keeping,” Ortloff explained.
The system is equipped with automatic alarms, and there is someone on-call at all times to respond to any problems with the system, such as a low water level in the tower.
Despite all of the testing, Ortloff said the also he depends on residents to let him know if there are water issues in a specific area.
“We encourage people to call the city office if they have a water problem. We need to know, and we can’t fix problems if we are not aware of them,” Ortloff said.
He added that he is always happy to investigate any water complaint that residents may have.
Another thing that residents can do to improve water quality in their homes is to maintain appliances such as water heaters. These should be drained each year to remove sediment.
Ortloff said residents may experience cloudy water due to sediment being stirred up by the flushing process. He advises people not to do laundry during these periods. If water does not clear up within a day after the flushing, Ortloff asks residents to contact the city office.
As the sun began to rise Friday morning and city residents were waking up to start their day, Ortloff and the city maintenance staff were finishing another round of behind-the-scenes work to maintain the city’s water system.