Notable St. Paul Reservoir Being Demolished and Replaced

From the Summer 2010 Waterline

Quarterly Newsletter of the Minnesota Department of Health Public Water Supply Unit, Waterline

A complete list of feature stories can be found on the Waterline webpage.

A reservoir in Roseville is being demolished after more than 90 years of service.

A landmark of St. Paul Regional Water Services (SPRWS) is coming down.  Since 1919, the utility has had a 30-million gallon reservoir in Roseville, one of the suburbs it serves.  Built alongside an open reservoir, which was then abandoned, the covered facility is 30 feet deep and encompasses more than 190,000 square feet.  The roof is supported by columns 16 feet apart with the connection to the roof and floor made by a barrel arch, obviating the need for reinforcing steel. 

The 1919 annual report for the St. Paul Board of Water Commissioners included this passage: “We have talked a great deal about our new thirty million gallong [sic] reinforced concrete reservoir, but believe it is excusable inasmuch as we are quite well pleased with it and because it fills a long-felt need.  Its construction was a larger undertaking than most people—even the contractors—realized.”

Above is one of two gatehouses on the site, which will be demolished along with the reservoir. On the right is the roof, which is of the groined arch type, supported by 21 inch square columns. Below is a photo from 1918 that shows construction on the 30-million gallon reservoir in what is now Reservoir Woods in Roseville. The east wall of the structure is completed. To the right is the open reservoir, which was abandoned after the new one was completed.

At the time of its construction, the reservoir served the high service system in St. Paul, which accounted for approximately 80 percent of the utility’s total demand.  (The low service area, which includes downtown St. Paul, the city’s West Side [across the Mississippi River from downtown], and the West Seventh Street area, accounts for the remaining demand.)  Over the past 30 to 40 years, however, the water in this reservoir has been used only for residents of Roseville.  According to SPRWS production division manager Jim Graupmann, Roseville averages only 5 to 6 million gallons per day, presenting challenges in maintaining the water quality with such a large reservoir.

The extra capacity, combined with structural concerns about the reservoir, led to a decision to demolish the reservoir and construct a smaller storage facility, a circular 10-million gallon tank with a diameter of 206 feet.  The concrete from the old reservoir and two gatehouses will be crushed and used as fill.  The existing floor, described by Graupmann as being “like an egg carton” as it arches up to the columns, will have the crushed concrete put over it to flatten it out and serve as a base for the new structure.  The new tank will be 40 feet deep and, with a domed roof, will stick up 15 to 20 feet higher than the previous reservoir.

The reservoir was taken out of service in December 2009 with a 48-inch bypass line being used to serve Roseville until the new storage tank is ready in mid-2011.