By Ivan Raconteur
LESTER PRAIRIE, MN Lester Prairie’s new water treatment permit took effect Feb. 5, and with it came new monitoring requirements and some new expenses.
Dan Wroge of PeopleService estimated that, with the addition of the new testing that is now required, Lester Prairie will pay about $19,000 in lab fees this year, and that estimate reflects a discounted price.
Wroge said PeopleService operates about 100 treatment facilities, and this volume has allowed the company to negotiate discounts with the lab and with equipment suppliers, and the company passes these savings on to the cities it serves.
The new testing requirements will be required in all cities that operate plants that discharge into the Crow River, according to Wroge.
The National Pollutant Discharge Elimination System (NPDES) permit for the city’s wastewater treatment plant is issued by the Minnesota Pollution Control Agency (MPCA).
One new area of monitoring involves what the MPCA describes as “salty discharges” from wastewater treatment plants.
Among the items that the city will need to monitor include chloride, magnesium, sodium, calcium, potassium, and total salinity at 25 degrees Celsius.
The new requirements apply to all industrial and municipal facilities where the receiving water stream flow to effluent design flow dilution ratio under low flow conditions is less than 5:1.
Wroge explained that when the water level is low, 90 percent of the water in some parts of the Crow River comes from discharge from water treatment facilities.
Wroge said the MPCA is concerned about the level of salt at Lester Prairie’s wastewater treatment plant because the city is in a hard water area, and most homes in the city use water softeners.
The city will need to monitor the additional items for a period of 10 months. If all of the samples are within acceptable limits, the city can petition to have the testing reduced from monthly to annually.
However, if any of the samples exceeds the limits, the MPCA could impose limits for the city, and the city would have to take steps to ensure that the city stayed within the new limits.
Wroge said he heard about one Minnesota city that was exceeding the new limits for salty discharges. In order to correct the problem, the city hired a company to adjust all of the water softeners in the city to run based on flow, rather than on time. This change was enough to bring the plant’s discharge to within acceptable limits.
The City of Lester Prairie recently discussed the possibility of applying for funding to construct a drinking water treatment plant to improve the quality of the city’s water.
Had this been approved, according to Wroge, PeopleService would have been able to control the level of salty discharge at that point by reducing the volume of salt that goes into the system.
Part of the reason that the MPCA has started to look closely at salty discharge from treatment plants, according to Wroge, is that it these discharges do not behave the way some other components, such as phosphorus do.
“Plant life doesn’t use it up, sunlight doesn’t break it down, and it doesn’t settle out,” Wroge said.
Another change under the new permit requires the city to have a mercury pollutant minimization plan.
Testing for mercury was added to the MPCA’s requirements based on changes to the US Environmental Protection Agency standards.
The new testing requirements that have been implemented in recent years have led to new some new jobs.
Wroge said the lab that PeopleService uses employed 12 people three years ago. In order to accommodate all the new testing that cities are required to do, the company is now up to 20 employees.
Although the new requirements have resulted in about 10 new tests being done at various intervals, one area of testing was reduced under the new permit.
Lester Prairie previously had to test for phosphorous twice per week. Now, that has been reduced to once per week.
Ortloff, who is the operator for Lester Prairie’s wastewater treatment plant, said he monitors both the influent and effluent at the plant (water coming in and going out).
Some tests require the use of “grab samples,” for which Ortloff draws a sample of either incoming or outgoing water.
Some tests require testing both incoming and outgoing samples to determine the percentage of certain elements that are being removed and to determine the efficiency of the plant.
Other tests use composite samples, which are made up of small quantities of water that are collected automatically throughout the day and combined to make one sample.
Wroge said the Lester Prairie plant is operating very efficiently, and is currently not using any chemicals to treat water, because the biological processing is working effectively. This saves the city money by reducing chemical expenses.
Ortloff said the plant’s operation includes daily monitoring of some items. Other tests are done weekly, bi-weekly, monthly, or yearly, depending on MPDES permit requirements.
Ortloff also monitors daily flow into and out of the plant, and daily precipitation.
He also calibrates testing equipment and keeps detailed records of a variety of information.
When samples are sent to the lab for testing, they are packed in a cooler to maintain temperature, and they are accompanied by a chain of custody form. A detailed label is attached to each sample.
There is a lot of math involved in running a treatment facility, according to Ortloff. For example, the readings taken for some tests must be multiplied by a conversion factor to arrive at a final result.
Ortloff submitts detailed reports to the MPCA monthly.