The random smell of rotten eggs is not uncommon in Commerce Township, and residents want to know why.
Giffels Webster will perform an odor study that will cover the area along Sleeth and Commerce roads, from the Huron Valley-Sinai Hospital east to the intersection of South Commerce Road.
“Giffels Webster, Commerce Township and the Oakland County Water Resources Commissioner (WRC) have received complaints of odor issues along this run of sanitary sewer over the past several years,” said Jason Mayer, PE, LEED-AP, partner, Giffels Webster.
This one-mile section of sanitary sewer, including 22 manholes, was recently rehabilitated as a part of the Sleeth Road Sanitary Sewer Rehabilitation Project. The rehabilitation provided protection of the pipe and manholes from severe hydrogen sulfide deterioration; however, the hydrogen sulfide is still present, and ultimately escapes the system and produces odors that are noticeably detected by residents.
“Hydrogen sulfide is detectable by smell in extremely low concentrations such as what we are studying in this area outside of the sewer system,” Mayer said. “High concentrations of hydrogen sulfide (such as what would be found actually inside the sewer system) are toxic, but for this area we are studying the very low levels that are detectable by smell at certain times outside of the sewer. The smell is not constant in the area – it occurs randomly. That is part of what we are trying to figure out.”
There have been several attempts to control the odor over the last two years. Giffels Webster has worked with the WRC to implement more frequent cleaning of the sewer, installed several different types of carbon filters at the pump station vent pipes, and installed a rubber mat to completely cover the pump station access hatch.
Elements of the study
While these attempts have slightly lessened the odors, a comprehensive study will be performed by Giffels Webster to investigate the most efficient alternatives to permanently control the odors in this area.
The study will involve:
Odor evaluation:
• Review the existing system configuration (force main, changes in slopes, pipe sizes, and pump station information) to identify potential sources of odor emissions and to determine monitoring locations for sampling data.
• Collect grab samples for gas and liquid phase hydrogen sulfide at the pump station and manholes along the upstream sewer.
• Conduct continuous hydrogen sulfide and differential pressure monitoring at the pump station and along the sewer to characterize the extent of odor emissions.
• Conduct ambient hydrogen sulfide monitoring near the pump station.
• Use a portable fan to determine the influence of air extraction at the pump station and locations along the upstream sewer.
• Obtain field olfactory measurements at various locations around the pump station.
Dispersion modeling:
• Create a dispersion model for the Hayes Creek pump station to characterize the current extent of offsite odor emissions (existing condition) using a modeling system (AERMOD.)
• Identify odor control goals relative to the modeled existing condition.
• Evaluate the extent of offsite odor emissions under various odor control strategies.
Alternatives analysis:
• Results of the monitoring program and modeling analysis will be used to evaluate the various treatment alternatives for the study area.
• A technology evaluation of liquid and vapor phase treatment technologies will be performed, including an analysis of odor control performance, footprint, operation and maintenance requirements, and life cycle costs.
• Technologies to be evaluated include liquid phase treatment (i.e., nitrate addition, iron salts) and vapor phase treatment (i.e., carbon absorbers, biofilters.)
• A matrix will be developed to summarize the results of the technology evaluation. Equipment and life cycle costs and associated design/performance criteria will be provided for alternative strategies that meet the odor control goals.
• Summarize the results of the odor evaluation, dispersion modeling, and alternatives analysis in a Technical Memorandum.
Mayer anticipates that this project will take approximately 2-3 months to complete once it begins, weather dependent, and the results will be presented at a future Commerce Township Board of Trustees meeting.
"smell" - Google News
December 16, 2020 at 12:21PM
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