December 12, 2016
By Marie Zhuikov
University of Wisconsin-Milwaukee researcher Sandra McLellan is heading one of five research proposals that received funding in a national annual competition by the U.S. Geological Survey (USGS). Her three-year proposal, “Detection of Sewage Contamination in Urban Areas of the Great Lakes,” has just begun and is using a combination of science and policy to improve water quality in urban areas. Steve Corsi, a research hydrologist with the USGS, is co-investigator on the project.
“Although there are regulations against it, untreated sewage release is widespread and chronic in urban waters,” said McLellan. “Much of it can be attributed to failing sewer systems and illegal connections, which can often go undetected.” McLellan’s lab has found that nearly 30 percent of local stormwater outfalls show evidence of such contamination.
For the science part of the project, McLellan and Corsi are using the $240,000 in federal funding for three things: to collect data on pollution loads in the waterways around Milwaukee and Wauwatosa, Wis., to develop an optical sensor tool that can estimate sewage contamination in real-time, and to look at associated pollutants, such as pharmaceuticals, that can harm aquatic life.
According to Corsi, the research team plans to analyze over 200 different pharmaceutical compounds, over a dozen viruses and different types of harmful bacteria in the water samples they collect. They are doing this using different methods and plan to compare them for consistency in order to help water resource managers choose the best one for their situation.
“Many people use only one of these methods to make a determination of pollution loading for their waterways,” Corsi said. “We want to know how different they are for instances when only one is available.”
The optical sensor is something that can be placed into a stream or sewer pipe. It emits a beam of light and a reading is taken that can be assessed in real-time. “We’ll be able to see how the pollution loading fluctuates on more of a five-minute basis rather than limiting ourselves to the frequency of water sample collection,” Corsi said, which could be very helpful for water managers.
While the optical sensor does not detect the presence of sewage itself, it can detect compounds that indicate sewage is present through a change in light absorbance or fluorescence. “We’ve shown in the past that sewage has a specific signature with optical properties of water that is different than the signature from environmental waters. We are doing this analysis to determine which optical signals may be worth pursuing to add to the mix of indicators and make pollution assessments more accurate,”Corsi said.
On the policy end of the project, the research team will work with water resource managers in
Milwaukee and Wauwatosa to adapt the optical tool and to develop policies that address wastewater infrastructure leaks.
“Urban wastewater infrastructure is aging throughout the country,” McLellan said. “The scope of the problem is startling, and requires billions per year to address. Unfortunately, only about 14 percent of that investment is made each year by Congress. The true economic costs of this deferred maintenance can only by determined by sound science to demonstrate the harm to water resources. We are working to understand this problem and find cost-effective solutions. We expect that this project will advance our understanding of sewage impacts on the Great Lakes and it will allow us to infer the extent of the problem in other cities across the country.”
In his letter supporting the project, Kevin Shafer, executive director of the Milwaukee Metropolitan Sewerage District said he anticipates the project will help his organization to better track and remediate pollution sources. “Rapid detection of sewage contamination will allow us to quickly respond to health risks and to formulate more effective management strategies to reduce water quality impairments.”