City rehabilitating 33rd Street water tank - The Electric

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The city has been draining the 33rd Street water tank this week to prepare for internal maintenance.

The water flowed through the southern portion of Dudley Anderson Park before flowing into 9th Avenue South toward 32nd Street South before entering the storm drain system, according to city public works.

De-chlorination tablets are present in a fenced location in the southern portion of the park and the water wasn’t expected to interfere with vehicle traffic.

The tank was expected to be emptied by the evening of Oct. 15.

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The maintenance is part of the $2.9 million rehabilitation project that was approved by City Commissioners in April.

The project includes some maintenance on the tank’s exterior.

Water users will likely not notice the tank being offline unless the system experiences a water main break, according to public works.

City staff successfully tested the system earlier this spring, before the work on the tank started.

City staff said there’s no way to capture all of the water but turned off the pumps, allowing as much water from the 33rd Street tank as possible to be used by residents.

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“There comes a point when the height of the water in the tank, which is what provides the pressure in the system when the pumps are off, is too low to provide the needed pressure in the system. Once the water in the tank reaches that elevation, the tank is isolated from the system and the pumps are turned back on to provide the pressure in the system. The water that remains in the tank at this point is what can be seen draining from the tank. There is a cost to draining the tank, but this maintenance will stop the leaks that are currently happening and in the long run will save the city money and treated water,” according to city staff.

The current maintenance schedule has the tank back online in January.

In April, commissioners unanimously approved a $2,941,050 contract to DN Tanks to rehabilitate the 33rd Street water storage tank.

The 33rd Street water storage tank was constructed in the mid 1940’s and this type of water storage tank typically has a useable life of approximately 100 years, according to city staff.

It is one of two water tanks on the main zone that serves two-thirds of the city.

The 33rd Street tank stores about 4.75 million gallons of water, which is 50 percent of the city’s total water storage capacity, according to city staff, and is one of two water tanks on the main zone that serve the majority of the city, from the Civic Center to Malmstrom Air Force Base, south of the Missouri River.

During the annual inspection, the dive crew noted cracking on the inner wall and excessive water leaking out of the tank.

Jason Fladland, former city water plant branch manager, told commissioners during the April 2 work session that they’d had problems with this tank for years.

City staff estimated the amount of water leaking out of the tank to be about 50 gallons per minute, or 26 million gallons per year.

Chris Gaub, city public works director, told commissioners during their April 16 meeting that the city is short about 10 million gallons, so if they were to build a new 20 million gallon tank, it would cost an estimated $22 million.

He said that if the city repairs the 33rd Street tank and later builds a 10 million gallon tank, it would save about $9 million.

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Gaub said DN Tanks is the same company that built the tank in the 1940s, but operating under a different name now.

The city retained Burns and McDonnell Engineering Company, Inc. to complete an evaluation of the tank.

The new tank will be rehabilitated and lined, with a two-year warranty and extend the tank’s lifespan by 10-20 years, as well as decrease the water lost through leaks, according to staff.

In October 2023, commissioners awarded a $366,365 contract to Advanced Engineering and Environmental Services, or AE2S, for design and inspection services for the 33rd Street water storage tank rehabilitation.

Fladland said that staff did a trial run in the spring and operated the city water system without the 33rd Street tank. He said no one noticed the difference as they were able to use other tanks for water storage. The city plans to do the project this fall when demand is low.

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The extended lifespan gives the city time to develop “the most effective and efficient long-term (100-year) strategy on water storage infrastructure,” according to staff.

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Fladland said in April that he estimated it will take about 12 weeks to repair the 33rd Street tank.

AE2S has designed and will provide construction administration and necessary certification documents.

The city received one bid for the project but “there are only a handful of companies that are qualified to do this type of work throughout the country,” according to staff.

DN Tanks, the original designer of the tank, submitted a bid of $2,941,050, which was within six percent of the engineer’s estimate.

Water enterprise funds were programmed and budgeted for this project, which was selected and prioritized under the public works capital improvement program.