East Bethel is planning to close the Castle Towers wastewater treatment plant by October 2013, but the city must spend about $2,000 to fix a problem a state agency recently discovered.
According to an April 4 letter from the Minnesota Pollution Control Agency (MPCA), East Bethel did not properly maintain the solids drying bed within the existing Castle Towers wastewater treatment system. Concentrated solids that settle at the bottom of the wastewater treatment tank within an enclosed facility are discharged to the outdoor drying beds. The solids are removed from the drying beds and stored in an outside bunker until they are eventually disposed of off site.
City Administrator Jack Davis said portions of the bed walls and liners need to be replaced or repaired.
The MPCA letter stated it discovered during a Feb. 1 inspection that “the drying beds are in a condition of disrepair.”
The MPCA wrote that the first drying bed “provides a direct route for solids or runoff from rain on the solids to contaminate the groundwater of the state through the break in the drying bed walls.”
According to the MPCA, the other drying beds liners conditions are unknown, but the inspection found the beds to be in a state of disrepair. The MPCA letter states that there is a potential in all the drying beds that roots from small trees could damage the liners, which could then impact the groundwater.
Davis said the repairs city staff have in mind will likely cost no more than $2,000 and the trees the MPCA referred to are really small saplings.
These small saplings and other vegetation will be removed from three of the four beds. One of the drying beds will be completely abandoned. A treated wood cap will be installed at the top of all dike and divider sections. The vertical plywood on the dike and divider sections will be inspected. Any damaged plywood will be replaced.
Davis said the city will inspect the liners on the bottom of the three remaining beds to see if there is any damage. It does not anticipate any damage.
The council March 21 approved the decommissioning of the Castle Towers wastewater treatment plant when presented with projected costs for keeping this facility functioning. City staff estimated that about $1.6 million of repairs would have been needed in 2013, which included $65,000 to reconstruct the drying beds.
Past 2013, City Engineer Craig Jochum estimated about $260,000 of repairs sometime in the next five years and a couple of other projects beyond 2030 that would add another $150,000 to the upkeep bill.
Instead of keeping this 38-year-old plant running, the council chose to close it. The residents in the Castle Towers mobile home park and the Whispering Aspen housing development will instead be serviced by the joint city and Metropolitan Council sewer project. A second forcemain will transport effluent from this area north of 241st Avenue and west of Highway 65 south to the new Metropolitan Council wastewater treatment plant facility on 185th Avenue.
Councilmember Heidi Moegerle asked if the repair costs could come out of the sewer project bond proceeds that are covering the upfront costs of the city and Metropolitan Council sewer project.
Davis said probably not because this old Castle Towers Wastewater Treatment facility is being decommissioned.
This forcemain project is estimated to cost about $4.2 million and will be first covered by the bond proceeds. The council has yet to determine how this specific forcemain project will be financed.
Davis said in March that the council will further discuss funding options this spring. If the council is interested in assessing existing Castle Towers and Whispering Aspen residents starting in 2013, a public hearing would be held this summer.
Eric Hagen is at [email protected]