City plans for sanitary system improvements
Flood worries continue to rise throughout the state as the spring season quickly approaches.
Infiltration problems in Osceola could increase as the melting snow and spring showers make their way through the town's already overloaded pipes.
"The whole city is already having an infiltration problem," said Mikelis Briedis of Veenstra & Kim. "Any moisture, whether it's snow melt or big rain event, is going to have a big impact. The system won't be able to handle it."
When the sanitary system is backed up with water, part of the sanitary flow will blow out of manhole covers and go into creeks. Briedis said this is illegal because the raw water doesn't get treated.
In February, Osceola City Council passed a motion to apply for State Revolving Funds (SRF) to improve the sewer system, which will hopefully reduce sanitary overflows. Costs for the entire project are estimated at nearly $4 million.
Briedis said these projects target specific areas in Osceola that have the worst problems.
The project will include installing additional sewer capacity along Grade Lake and between the new Grade Lake sewer and Filmore Street.
The project will also replace a force main from the the old plant lift station to the wastewater treatment plant. A sewer that has multiple structural defects between Park Street and Adams Street, south of Washington Street, will also be replaced.
Where citizens will see the most effect of this project is in a proposed program to disconnect homeowners' footing drains from the sanitary sewer system in the Delaware and North Main Pumping station basins and put in a sump pump.
The Delaware station serves most of the houses north of Mclane Street and west of Main Street; the North Main station includes neighborhoods by Roosevelt Street, north of Ayers Street and east of Main Street.
Footing drains are located underground and allow water to be pulled away from the house. But direct connection of these drains to the city's sanitary sewer system causes an overload in pipes and raw water to bypass treatment.
And when it rains, the city has a problem.
These drains increase the amount of flow in the sanitary sewer system.
"With the rain, the pipe could be totally full," Briedis said. "Then it backs up into that person's basement."
Briedis said a previous Osceola project and investigations from other cities have pinpointed footing drains as a major contributor to the increase in flows.
"On Ayers Street we replaced the sanitary system and manholes, and we were still getting peaking factors in this area," Briedis said. "If there isn't leakage from manholes and city sewers, it has to be coming from the private side."
Briedis will recommend that the areas that have the most infiltration problems have footing drains removed from houses.
"What the city should do is target the areas that are most critical," he said. "And other areas that aren't causing the same level of financial damage to the city, well that would be up to city as to what time they would ask the people to remove their footing drains."
To find these connections, a non-toxic dye is inserted into the system.
"There are different ways you have to look for it," said Briedis. "Generally this involves the cooperation of the property owner to get on their property. We'll methodically go through the entire neighborhood."
Houses without basements typically don't have footing drains or connections around the perimeter of the home.
Briedis estimated that the cost for the property owner would be about $2,500, depending on the type of work that needs to be done and how the drain is connected.
The city would be responsible for any work done in the city's right-of-way
Disconnection typically means digging a 7-foot hole in front of the house to install a sump pump then connecting the footing drain in with the sump pump and repair the service line.
"Footing drains are still a good thing to have, otherwise you have wet basement," Briedis said. "The only problem is that we can't have the drain discharge into the sanitary sewer system."
Briedis has completed this project in many other towns.
"Osceola's not unique," he said. "So a lot of people are dealing with the same issue."
In Indianola, Briedis said 50 percent of the homes were found to have footing drains.
Briedis calls Osceola's infiltration and bypass problems a "big issue."
Construction for the Grade Lake project could begin as soon as this summer if the project is funded, Briedis said. Other projects are still being designed.
"The state has put a lot of emphasis on eliminating bypass," he said. "It hasn't been legal to bypass, so what's happening in Osceola is illegal. I anticipate the city will be getting a mandate from DNR to eliminate their bypassing in a 3-year time period."
