The Minnesota Pollution Control Agency (MPCA) is now taking comments on the planned expansion of Pipestone’s wastewater treatment plant.
The public comment period opened March 8 with the posting of the Environmental Assessment Worksheet (EAW), which details the proposed project, and closes April 7. Comments received will be used by the MPCA to evaluate the potential for significant environmental effects.
The intent of the EAW is, “to gather as much information in the beginning as we can of the potential environmental impacts,” said Nancy Drach, a planner/principal with the MPCA environmental review process out of St. Paul.
Those impacts can be both long and short term, and include everything from discharge impacts on the receiving waters to air quality issues during construction.
The state mandates the environmental review process when modifications or expansions to existing wastewater treatment facilities (WWTF) increase by 50 percent or more and by at least an additional 200,000 gallons, Drach said.
Pipestone’s current facility, built in 1989, is currently permitted to treat a maximum average wet weather flow of 600,000 gallons per day. Under the expansion, two ponds would be added to the four existing ponds, increasing the capacity to 930,000 gallons per day.
The improvement is expected to provide Pipestone with enough increased capacity for the next 20 years.
The MPCA is requiring the expansion before it lifts a moratorium the agency imposed on Pipestone early last year banning new sewer connections. The moratorium resulted because the ponds frequently received more than the 600,000 gallons of wastewater that the system was designed to treat or store. As a result, violations have occurred over the years, and wastewater has been discharged outside acceptable discharge periods into the receiving waters of Pipestone Creek — though the city hasn’t had to bypass, or dump untreated sewage, since 2006, according to the MPCA.
“My average (daily gallons) on a monthly basis is usually over 600 (thousand gallons per day),” said Joel Adelman, Pipestone water/wastewater supervisor. “It’s usually about 640 (thousand gallons per day).”
Typically when municipalities expand wastewater treatment facilities, land accessibility and cost often force communities to move to a mechanical facility, Drach said. Pipestone’s continuation of the pond system, “is probably the more unique aspect” of the project, Drach said, stressing, “it’s not a bad thing.
“If it works, that’s what matters,” she said.
The city looked at constructing a mechanical plant. The cost would have come in around $13 million, according to Lance Weatherly, of Banner Associates, the city’s engineer for the project. Expanding the capacity of the existing plant was viewed as the most cost-effective approach, Weatherly said.
“There’s no way the community could absorb a ($13 million) bond, and grants aren’t out there the way they were in the early 80’s to expand treatment facilities,” Weatherly said. “A lot of plants were built when the Clean Water Act came out. With the budgets and recession, there isn’t any money out there.”
The city was twice rejected for a grant that would have financed the expansion. At this time, the city hasn’t determined how it will pay for the project once all approvals are obtained. Options include a combination of Public Facilities Authority (PFA) loans, U.S. Department of Agriculture (USDA) loans and municipal bonds.
The estimated cost of the project, including the land the city purchased last year to build the expansion, exceeds $3 million.
Phosphorus
At least one aspect of Pipestone’s existing operation would change once the improvement is constructed. Instead of simply monitoring phosphorous levels when wastewater is discharged, the city would be required to limit the phosphorus concentrations.
A Minnesota phosphorus rule that went into effect in 2008 (7053.0255, subp. 3.A.(3)) requires, “phosphorus removal to one milligram per liter (of water)…when the discharge is new or expanded…except when the discharger can demonstrate to the commissioner that the discharger qualified for an alternative phosphorus limit…”
Steven Weiss, MPCA research scientist, has recommended an alternative rule for Pipestone after the improvements are completed. Weiss said Pipestone will have to reduce its concentration from existing levels, but at full capacity, the maximum would be 1.6 mg/L of water, rather than the 1 milligram, as long as wastewater is not discharged between May 1 and Sept. 30.
“Algae in rivers and lakes typically grow during that period,” Weiss said. “It’s the optimal time for them to grow. So they (Pipestone) won’t be discharging when the input would be the greatest.”
Phosphorus is used in fertilizers because it aids vegetative growth. When excess amounts enter surface waters through either point sources (municipal or industrial wastewater plants) or nonpoint sources (runoff from agricultural fields, feedlots, urban areas, fertilized lawns and businesses like car washes), the nutrients can create bumper crops of algal blooms. The blooms are not just unsightly, they diminish water quality. As the algae decomposes, it uses up available oxygen supplies, sometimes threatening the survival of fish and other aquatic organisms, according to the MPCA.
Weatherly said that by expanding the plant’s capacity, the water will be held longer and not discharged during the summer months when the water is more apt to green up from phosphorus loading.
“So by expanding the facility, they can retain it (the wastewater) longer and not discharge during that period,” Weatherly said.
Pipestone currently monitors phosphorus even though it doesn’t have a limit. So officials know they’ve got to knock down levels to meet the requirements once the improvement goes on line.
Currently, those levels run between 2 and 3 m/L of water; when discharges must occur before the natural processes have had time to clean the water, those levels reach 3 and 4/mg/L of water, according to Adelman.
Residents contribute to the phosphorus loads when they use dishwashing detergents that contain phosphorus or when fertilizers from chemically-treated lawns wash into the system via faulty storm sewer pipes, to name just two nonpoint sources. The city also treats the public drinking water supply with phosphorous to control corrosion — the phosphorus coats the inner walls of the water mains and service lines running to houses so that chemicals like copper, lead and iron don’t leach into the water.
The most significant contributor of phosphorous to Pipestone’s waste stream, however, is J&B/Ellison Meat Co., due to blood, marinades, cleaning soaps and detergents in the company’s industrial waste stream, according to the city’s “Phosphorous Management Plan,” recently updated in 2009.
“They’re probably 75-to-80 percent,” of the total phosphorus loads in Pipestone’s wastewater, Adelman said.
When the city tested pre-treated wastewater from Ellison Meat Co. in 2009 to update its Phosphorus Management Plan, the phosphorus concentration was 91.80 mg/L of water, according to a sheet submitted to the County Star by both the city and Banner Associates.
The only other business tested and identified by the city as a significant contributor of phosphorus was the Pipestone Veterinary Center Truck Wash, where livestock waste from trailers and cleaning soaps contributed to a phosphorus concentration of 14.90 mg/L of water.
Both companies feed their waste to Pipestone’s pre-treatment plant, where city employees, with financial assistance and cooperation from Ellison Meat Co., have worked together to try and reduce the phosphorus concentrations. (See story on the pre-treatment plant).
The Pipestone Vet Clinic Truck Wash now uses phosphate-free soaps, Adelman said, and contributes financially to the chemical treatment of phosphorus at the pre-treatment plant. Ellison Meat Co. has worked with the city from the beginning, donating the land for the pre-treatment facility and funding 50 percent of the costs associated with the operation of the plant on an ongoing basis, according to Brian Karels, J&B/Ellison Meat Co. vice president of production.
“The city and Ellison’s have been proactively working on solutions at the pre-treatment facility to manage the phosphorus levels in advance of state mandates,” Karels wrote in an email to the County Star. “We will continue to assist where feasible.”
If the limits of 1.6 mg/L of water are not achieved once the improved plant goes online, the city would be forced to chemically treat the water with ferric chloride to reduce the phosphorus concentrations, a solution that Adelman said is costly.
“For four discharges in a year, you’re looking at about $100,000,” Adelman said.
Topeka shiner
Another issue identified in the EAW pertains to the Topeka shiner. Pipestone’s wastewater treatment plant discharges into Pipestone Creek, a designated critical habitat for the federally endangered and state-listed special concern fish. The Minnesota Department of Natural Resources identified the project as one that may impact the fish and require a review from U.S. Fish and Wildlife.
Fish and Wildlife, after reviewing the expansion, noted recent records of the species in close proximity to the existing discharge pipe and will require the city to monitor the water. The agency is recommending that Pipestone install gauges within 300 feet upstream and downstream of the wastewater discharge pipe to take specific measurements and calculations one hour prior to discharge, halfway through discharge and one hour upon completion of discharge.
“This monitoring will help us better understand the existing conditions within Pipestone Creek, and allow us to develop a baseline of information to which we can compare future discharge increases and determine potential impacts to the Topeka shiner,” wrote Tony Sullivans, Fish and Wildlife field supervisor, in a letter attached to the project EAW.
