City water works

By Kim McDarison

While firefighters battled the five-alarm fire at the D.B. Oak building on Aug. 10, several Fort Atkinson residents learned, perhaps for the first time, about drawdown cycles within the city’s water reserves. 

Drawdown cycles aren’t new, City Engineer Andy Selle and Water Utility Supervisor Tim Hayden said.  

During an Aug. 10 media briefing, and again during a Fort Atkinson City Council meeting held Tuesday, Fort Atkinson Fire Chief Daryl Rausch reported that one of the city’s water towers had been drawn down to 12 feet of water, which, he said during the media briefing, “is very near the minimum amount that we need to operate the city.”

Even as firefighters used approximately 1 million gallons of water to subdue the fire on the first day of what would become a multiple-day event, the city was never in danger of leaving its utility customers without water, Selle and Hayden said. The system is built to accommodate large fire events that might require large amounts of water, they noted, adding that even as utility users were learning that one of the city’s water towers had water levels of around 12 to 15 feet, the second of the city’s two tanks still had a water level of about 32 feet. Tanks are at full capacity at 40 feet, Hayden said. 

So how does the city’s water utility function, and how does drawdown affect it? 

In response to our questions, Selle and Hayden recently sat down with Fort Atkinson Online and offered an overview of the city’s water utility system, including how it might be affected by large-scale water usage such as fighting fires. 

How does the system work?

The city’s utility uses a system with several components, Hayden and Selle said. 

A historical date associated with the beginning of the city’s water utility might be 1901, the year in which the now-decommissioned water tower at the corner of South Fourth Street East and High Street was built. 

Documentation provided by Selle begins with some 35,297 feet of water main piping placed between 1901 and 1920. Today the city has 396,371 feet, or approximately 74 miles, of piping of varying sizes and ages. 

Also documented are the ages of the city’s deep-aquifer wells. Wells, designated No. 1 and No. 2, have been decommissioned, with those dates unknown, Selle said, adding that a decision to decommission those wells might have been made because they weren’t deep enough or they were perhaps located in a disadvantageous spot.

Of the city’s five active deep-aquifer wells, No. 3 was dug in 1931; No 4, in 1946; No. 5, in 1952; No. 6, in 1958, and No 7, in 1967. 

All of the city’s wells are approximately 1,000 feet deep. As a matter of comparison, Selle said, the average private well in the area is approximately 100-200 feet deep. 

The number of wells a city might need is developed using population statistics and also the amount and size of industry in the area. In Fort Atkinson, Hayden said, Jones Dairy Farm on Jones Avenue and OSI on Industrial Drive are two of the utility’s largest water users. Industrial utility users are responsible for about 45% of the city’s total water consumption, according to a chart shared by Selle and developed in 2019. 

Other water consumers, according to the 2019 chart, include residential consumers, who account for 28% of consumption; commercial users, who account for some 10%, and consumers in a category labeled “multi-family,” who use 4% of water generated by the system. Two other categories: “system users” and “public” each consume 1%. Another 11% of consumption is attributed to “water loss,” according to the chart. 

Additionally, the chart noted, in 2019, on an average day, water demand used by the city’s utility rate payers was 1.81 million gallons per day, as compared to a maximum usage day, when demand was calculated at 3.35 million gallons. During peak usage hours, demand was calculated at 3,700 gallons per minute.

Under normal circumstances, Selle said, city staff plans for peak usage drawdowns and allows time in-between for the system to replenish its reservoirs. Also water peak demand is not normally sustained for 12 hours continuously.  

Water is pumped from the five active wells into the system where it’s carried through main and lateral pipes to various system components throughout the city. 

Among the miles of piping, Selle said, age and size varies. 

The larger pipes, up to 18 inches in diameter, are typically used as mains. Water mains bring water to smaller pipes called laterals, which connect homes and businesses to the city system. While the utility-owned equipment, such as wells, towers, reservoirs, booster stations and mains, are maintained by the city, property owners and the city share responsibility for maintaining laterals, Selle said, adding that the city is responsible for the lateral from the main to the shutoff valve in the terrace; the property owner is responsible from the terrace to the building. 

The smaller pipes — some as small as one inch in diameter — are typically among the city’s oldest. One-inch pipes still active in the city’s system were installed between 1941 and 1980, according to a utility report generated in 2020. 

The city has 31,565 feet of 16-inch in diameter pipe, a majority of which is used as mains connecting the city’s 600 water hydrants, located nearly every two blocks throughout the community. 

Within the system, the city has two elevated towers and two reservoirs all of which store water and contribute to generating water pressure, Hayden said. 

To create water flow and pressure, elevated towers use gravity and reservoirs use pumps. To help increase flow, the system has three booster pumping stations. In the southwest corner of the city, there is also a pressure zone supplied by one of the booster stations, Hayden said. 

To create the kind of water pressure people typically like in the shower, the system produces 60-70 pounds per square inch (psi). While pressure in communities may vary, Selle said, that’s an industry standard. 

When the pressure falls below 35 psi, Hayden said, that’s when people begin to notice. During the D.B. Oak building fire, he said, he did not receive any calls from people who were advising him that their pressure was low. 

Although, Selle said, “an extended event like the fire could cause this to occur.” 

Customers usually notice low-pressure events, Selle said, but pressure that is too high can also create concerns. 

That’s when the fixtures in homes and buildings are at risk. Gaskets could fail and pipes could break, he said. 

What happened during the fire?

Looking at Aug. 10, the day the fire began, Hayden said, the first thing to understand is that both of the city’s tanks hold 40 feet worth of water. That’s the depth of the tanks, which equates to about a half of a million gallons in each tank. The city’s full reserve of water is 1.635 million gallons. 

Reserve, he said, is what’s being stored for usage. 

“When thinking of supply, that’s what we can pump out,” Selle said. 

“During the fire, we maxed out at 4,600 gallons per minute,” Hayden said. “And we did that continuously for 12 hours,” he added.  

“Each of the city’s wells are capable of pumping 1,000 gallons per minute. So all the wells working together were able to pump the 4,600 gallons per minute needed to fight the fire,” Hayden continued. 

During a normal day, Selle said, some of the city’s wells will run for about an hour and then the pumps will turn off for five or six hours. 

The system, which is completely automated, is always communicating with its components, Hayden said. 

On an average day, the city uses about 1.8 million gallons of water. The components of the system, the five wells, two towers and two reservoirs share the load, Selle said. The wells do not pump out water constantly throughout the day, as they did on Aug. 10. 

With a normal day, the city works to store water in the tanks and reservoirs by pumping water from the wells in advance of peak usage times, which, Selle said, are typically in the morning and evening, when residents are home. Using that timetable, Selle said, the reservoirs are full during times of high demand. People take showers in the morning, use the water in the reservoirs, and then the pumps go to work to replenish them. The water is replaced in the reservoirs in advance of each predicted time of peak usage, he said.  

Within the reservoirs is also water that is being stored just in case of fires. Most of the system is built for fires — most of the system is built to supply water for fire protection, he added. 

During the Aug. 10 fire event, after 12 hours, one of the city’s water towers, the one on the north side, was drawn down to a low, but at the same time, the tower on the city’s south side was at 31 feet, and both reservoirs were full the entire time, Hayden said.  

To replenish the towers, Selle said, the system needed time to pump more water from the wells. 

Looking at the dynamics of the towers, he said, “we can pump more water into them than we can out of them. 

“That means we can pump more in from the wells. Once they are full, we use booster pumps to pump water into the mains. That’s our full distribution system. The water flows from the wells to the towers and reservoirs, which fill simultaneously. Well 5 is the only one that pumps directly into the Jones reservoir which holds 300,000 gallons.” 

The other reservoir, the downtown reservoir, holds 250,000 gallons, Selle added. 

How fast water can be delivered and from which part of the system it draws first is determined by the size of the main and the location of the asset, Hayden said. 

The south tower is located near the larger industrial users and has a larger main to deliver water more quickly. Residential areas have smaller pipes, Selle said.  

Older piping in some parts of the city provides challenges, Selle said, adding that fighting the fire was a great example of those challenges. 

“In the older area of the city, we did not have 16-inch mains nearby, so we did not have the ability to deliver more water to meet the need. As pipes get smaller — as you neck down water — you are not able to run 4,000 gallons per minute through the fire hose,” Selle said.  

On Aug. 10, firefighters were distributing water at the site at a rate of about 1,000 gallons per minute through each of at least three hoses, Hayden said. 

“They were draining water faster than we can recover it. The north tower was closer to the fire so it dropped faster,” he added.

While the system is connected, Selle said, “it takes water from the path of least resistance first. In this case, with this fire, that was the north tower.” 

To engage with utility assets on the city’s south side, Selle said, water drawn must flow through pipes underneath the Rock River.  

“It has to go a big distance. With water, the further the run, the less water (firefighters) can get,” Selle noted. 

Describing the city’s system, Selle said it is splint between the city’s north side and south side by the Rock River. The two sides are connected by two mains, a 16-inch line and a 10-inch line, both of which carry water under the river. 

While the water needed for the fire was pulling from the entire system, it will pull from the nearer point in the system first because it is closer, so the north tank was being drawn down faster than the south tank during the fire, he said.  

Would the firefighters have needed even more water, Selle said, there is an option to draw water out of the river, but, he said, while that option is available in theory, he has never used it. 

“It has never been done here, at least since I’ve been here, and that’s since 2015,” he said. 

“In the downtown area, many of the pipes are older and are 2 inches in diameter. Those sized pipes work great for residential needs, but they are not the best for fighting fires. If there was a large fire downtown, the river might come into play,” he added.  

What might have been done differently?

Said Hayden: “If everybody would have stopped using water, it wouldn’t have helped them (firefighters).”

“Your shower uses less than two gallons per minute (of water) and that’s the biggest draw in a house,” Selle said, adding that even as utility consumers used water during the fire event, that usage would not have made enough impact to the water supply needed by firefighters one way or another. 

“During the event, we got no calls about low pressure or people with color in their water. When the hydrants are flushed, some people get color in their water,” Hayden said, adding that the drawdown and pumping throughout the system during the fire event had an impact that might be similar to flushing the city’s hydrants. 

Typically, he said, “the city flushes hydrants twice a year. A lot of residents understand they can expect that (color in water) and it clears up quickly. 

“We do that to keep the water clean,” he said, adding that the drawdown and restorative pumping ostensibly added another cleaning cycle to the city’s system.