Saline City Council held a work meeting Nov. 3 to discuss plans to study solutions to the foul odors emanating from the Wastewater Treatment Plant (WWTP). A representative from Webster Environmental Associates of Louisville, Ky., came to talk about a proposed study to isolate the causes and propose solutions.
Earlier, city staff had prepared a Request for Proposal (RFP) and several companies showed initial interest, but in the end only Webster came forward with a detailed proposal and bid.
For the Saline project, Webster would work in concert with Tetra Tech to solve the odor problem.
Jim Ross of Webster began his presentation by reviewing case studies where his company had helped other clients. In most cases biological scrubbers or biofilters were used to eliminate most of the odor problems at a minimal cost.
The study would begin with a collection of input from neighbors and a sampling program. Webster would use equipment to continuously monitor hydrogen sulfide levels.
Hydrogen sulfide is a component of sewer gas usually described as having a “rotten egg” odor. Humans can smell it at extremely low concentrations, as low as 1 part per billion (ppb). Toxic levels are hundreds of times greater.
They would also analyze for another class of smelly sulfur-containing compounds, thiols. In addition, they would collect air samples for an odor panel.
An odor panel is a group of people who sniff samples and rate them. By smelling successive dilutions of the samples, the panels can quantitate how much odor reduction is needed to make the air quality acceptable.
The first such sampling would take place during a week in March and would be followed up by a second week of sampling in June. June would provide better data because smell generation is usually greater in warm weather, but doing a study in March would lead to a quicker understanding of the problem.
In addition to analyzing chemical components, Webster would study the neighborhood of the WWTP, quantifying where the odors are worse and with what frequency.
When the sources and components of the odor problem are identified, the company would then recommend solutions to alleviate the problem. These could be physical, chemical or biological.
An example of a physical method would be adsorbing odor-causing chemicals onto an activated carbon filter. Chemical methods usually involve oxidizing the odor causing agents with chemicals to convert them into less odiferous, less volatile and more water soluble compounds.
Biological solutions would use microbes to do the work of the chemicals. Enzymatic reactions in the microbes would oxidize the compounds without the need for continual chemical input.
Council member Janet Dillon asked Wastewater Treatment Superintendent Bob Scull if visitors at the recent WWTP open house had come to a consensus as to where the odors seemed strongest. He said that they had.
Dillon then asked if the city could skip hiring a contractor for a comprehensive study and just act on that knowledge.
“That’s what we did last time and it didn’t accomplish our goals,” said City Manager Todd Campbell.
Scull suggested that a quantitative study was needed to determine how much odor scrubbing was needed. Ross said that odors noticed by open house visitors could be very localized and contribute little to area-wide odor issues.
He said that plumes of vapors from large scrubbers could rise up into the air and come down farther away from their source. They might not be noticed by somebody standing near the scrubber.
After continued discussion, the council agreed that it would be wise to proceed with plans for a study and probably do both quantitative samplings proposed by Webster. The issue will be on the Council agenda for an official vote on Monday, November 14.
Two people came forward to provide input during the citizen comments part of the agenda, Mary Hess and Bonnie Armbruster. Hess suggested that the WWTP odor problem may be due to septage from outside the city that is brought into the facility by septic tank pumping services. Armbruster came to vent her anger and frustration.
Armbruster lives northeast of the WWTP, receiving perhaps the worst of the odors, delivered by the prevailing southwest winds. She said her house was appraised at around $200,000, but thanks to the odor problem it is now “worth nothing.”
She also said that she has been ill lately and that she was “almost positive” that the WWTP odors were the cause. True or not, there is no question that the odor problem has diminished her quality of life.
Fortunately for her and her neighbors, Council is in the process of addressing the problem.
North Ann Arbor Street Railing, Steps Approved
A second item was also added to the work meeting agenda. The issue was how to deal with the dangerously high sidewalk on North Ann Arbor Street near the site of the former Detroit Dog Company, the former Drowsy Parrot and the Carmody Law firm.
The sidewalk recently installed by Hoffman Brothers was built that high to make it ADA compliant. Unfortunately, people working on the streetscape design failed to foresee the problem that would be caused by the elevated walk.
Campbell outlined a plan to install a railing and some steps at specific places to enable people to go up and down from street to sidewalk. The cost of the fix would be between $15,000 and $20,000, Campbell said.
Council discussed various details of the plan. The decided they needed to proceed with the repair, but they would talk to URS, the company that drew up the plans for the Michigan Avenue project, about sharing in the cost of fixing the problem.