SOLDIERS GROVE - Small, rural villages in Crawford County are struggling with the Wisconsin Department of Natural Resources (WDNR) requirements to reduce phosphorous levels in effluent from their wastewater treatment plants. The requirements in place mean that the aging plants are looking to bring the phosphorous levels in effluent to the 1.0 mg/L level.
Historically, this situation came about when in April 2010, the U.S. EPA warned that if WDNR did not adopt phosphorus standards by the close of 2010, and nitrogen standards by 2013, EPA would begin the process of determining whether to establish standards for the state. Just two months later, the Wisconsin Natural Resources Board adopted phosphorus water quality standards and set regulations that would establish phosphorus pollution limits in water pollution permits. The criteria and regulations went into effect in December 2010 .
In all cases, this means that these villages are looking at capital improvements to infrastructure that for the most part exceeds their capacity to raise the funding. Efforts are underway to see what kind of grants are available to help defray costs. In some cases, villages such as Gays Mills and Soldiers Grove are exploring the possibility of collaborating on a joint project.
Recently, both villages had presentations from Davy Engineering about needed upgrades to their existing systems and what it would take to a collaborate on a new, state-of-the-art plant.
If the Village of Soldiers Grove decides to invest in upgrades to their current system, the report details that it will require a significant amount of capital. The treatment plant upgrades with tertiary filtration is calculated to raise sewer rates to 3.36 percent of the median household income. Sewer rates are currently at 1.42 percent of median household income.
The report states that the alternative of joint treatment with the Village of Gays Mills is a viable alternative, but the two communities are on different compliance schedules. To move a joint project forward, an agreement must be reached between the two villages and funding must be obtained.
If joint treatment is not approved, then pilot testing will need to be performed after structural issues that allow infiltration and inflow of water and nutrients into the system from low-lying parts of the village are addressed. This testing will allow the village to determine how much chemical dosing will be required to achieve phosphorous goals, and how much sludge would be produced.
Without being able to use their drying beds, it would also require construction of a sludge storage tank. In addition, the current aerobic digester may be too small for the potentially greater amounts of sludge generated by the addition of chemical treatments.
On Thursday, Dec. 12, Davy Engineering provided a report to the Soldiers Grove Village Board about their wastewater treatment plant. The report detailed the challenges the current aging facility is facing and the upgrades needed to address those challenges. The timeline for making the upgrades as well as the estimated costs of making them were provided in the report. The report addressed two new businesses in the village, and how the village would need to work with them to control phosphorous coming into the treatment plant. Estimates of what it might cost to pursue a joint project with Gays Mills were also presented.
The village’s existing plant is described as “an extended aeration package treatment plant” which treats wastewater through a process that includes a manually cleaned bar screen, activated sludge aeration, clarification and seasonal chlorination/dechlorination. Waste activated sludge is pumped to an aerobic digester and then sent to sludge drying beds. Currently, the village is replacing the plant’s chemical feed equipment because of lack of availability of repair services or replacement parts.
To meet phosphorous goals, the village will need to add a chemical feed system expansion and upgrade. The existing structure does not have sufficient space to accommodate such an expansion. The village has already been required to discontinue use of the sludge drying beds because they were built without an underlying impervious layer to prevent downward movement of nutrients such as phosphorous or nitrate into groundwater. This has resulted in added costs to the village to have their liquid sludge pumped and hauled.
A big problem for the village is sections of the old town that are frequently impacted by flooding and high water. This causes the gravity flow sewers in the low-lying areas of the village to be impacted by what is called “infiltration and inflow.”
The solution proposed in the report is for those gravity feed sewers to be abandoned and converting the piping in the area to pressure sewer or force mains. All homes and businesses within the flood-prone area would be converted to using a grinder pump station that discharges to a pressure sewer system, so when flooding occurs, those properties could be isolated and turned off during the high flows.
There are also problems with several of the lift stations used in the village’s system. Those two lift stations are Lift Station No. 1 or the ‘Main Street Station,’ and Lift Station No.2.
Lift Station No. 1 is in the regulated floodway and has been damaged from flooding in recent years. This has required replacement of an electric motor for one of the sewage pumps in the dry well. The dry well has also been inundated with floodwaters. During major flooding the lift station has only been accessible by boat through the flood waters. This lift station will be relocated approximately 400 feet northeast of the current location.
Lift Station No. 2 has also been surrounded by high floodwaters in recent years and was recently flooded. This lift station will need to be raised to prevent flooding of the station, and the control panel will be stabilized to prevent damage by floodwaters.
In the plan for the village’s treatment plant, repairs to the lift station will be required to be completed in ‘year two’ (2021) of the five-year plan (2020-2024) to bring the system into compliance. Also in 2021, plans and specs for the sewer collection system improvements will need to be submitted.
The village is also being asked to construct a completely new lift station – Lift Station No. 5. This station will be located southwest of the Kickapoo River to collect flow from the southwest area of the sewer collection system. The force main from the station will be constructed through the low-lying area in the village. If the village chooses to go forward with its existing plant, then sewage from this part of the system will discharge to a junction manhole upstream of the Main Street Lift Station. If the village goes forward with a joint project with Gays Mills, then the new lift station will become the new Main Lift Station.
Water quality trading
In addition to all the other options facing the village, they are also being required to look for opportunities to participate in water quality trading.
According to the WDNR ‘Water Quality Trading How To Manual,’ Water Quality Trading (WQT) may be used by municipal and industrial Wisconsin Pollutant Discharge Elimination System (WPDES) permit holders to demonstrate compliance with water quality-based effluent limitations (WQBELs).
Generally, trading involves a point source facing relatively high pollutant reduction costs compensating another party to achieve less costly pollutant reduction with the same or greater water quality benefit. In other words, trading provides point sources, such as the Village of Soldiers Grove, with the flexibility to acquire pollutant reductions from other sources in the watershed to offset their point source load so that they will comply with their own permit requirements.
The system works by giving a municipality a 2:1 or 3:1 trade depending on the phosphorous reduction practices employed, with the village paying for the cost of restoration projects. The village would then receive credit for phosphorous reduced elsewhere in the watershed by another partner.
In order to implement a water quality trading project, the village would need to enlist help from the Crawford County Land Conservation Department and the WDNR. The village’s sewer plant currently discharges to the Kickapoo River in the Reads and Tainter Creek Watershed of the Lower Wisconsin River Basin.The report states that the village has a potential water quality trading project on a property it owns along Baker Creek. The project would be a streambank restoration project. Water Quality Trading projects are usually streambank restoration, land cover conversions, farmland buffer strips, storm water detention or feedlot improvements.