A consulting firm is recommending that nearly $14.7 million be invested through 2030 to construct a new storage facility, tank and numerous other improvements for the Northfield wastewater treatment plant that also serves Dundas.
The results of the wastewater treatment plant operations and facility study, compiled by Dallas-based Jacobs Engineering, were announced Tuesday during a Northfield City Council work session meeting by Group Project Manager John Borghesi. The plan is expected to come back before the council at a future meeting.
The wastewater treatment plant’s existing sludge holding tank allows for only three days storage. Borghesi said adding a 360,000-gallon storage tank for $3.8 million would increase sludge storage from three days to 10, giving staff more time to correct major equipment failures. Also, Jacobs recommended demolishing and replacing the existing biosolids cake storage facility for $3.9 million. That replacement would reportedly increase the maximum storage limits from the current 40 to 80 days to 180.
Other recommendations include replacing the biological aerated filter process blower for $2.1 million and spending $3.62 million for equipment renewals. Also, Jacobs found on-site control system and card access system upgrades would cost $864,000, and that the on-site well “has limited capacity and will not meet the demands of a fire suppression system.” According to Jacobs, it would cost $1 million to connect the water supply if fire suppression is required.
Currently, through an agreement, Dundas is allowed to use up to 4.6% of the Wastewater Treatment Plant facility load. Northfield Utilities Manager Justin Wagner noted the numbers identified in the report included projected population growth in both Dundas and Northfield. Drafts of the plan were also released in October and January.
In January 2018, flooding of the biological aerated filter in the basement due to a pipe plug failure caused 5 feet of water to flood the basement and 200 gallons to be released to the ground. Then, in May of that year, a fire in the biosolids handling facility caused significant damage, requiring emergency biosolids handling, an emergency treatment system, and repairing and rebuilding the permanent facility. In July 2018, a pipe failure in the sludge pump room caused 6 feet of wastewater to flood the basement and 1 million gallons of untreated waste water being discharged into the Cannon River.
In May 2020, Jacobs recommended the city hire an additional wastewater treatment plant supervisor to accommodate the facility’s size and better document maintenance procedures.
A number of recommendations established in a 2016 facility plan have already been completed, including ultraviolet disinfection, biosolids processing facility work, and the replacement of a Biological aerated filter gate.
Councilor Jessica Peterson White asked whether there were any other energy efficiency measures the city could take to reduce usage, like placing solar panels on a roof. Wagner noted that as part of a solar study, wastewater plant roofs were identified as potential locations for solar energy generation.