What’s that Smell? Manhole Inserts Assist in Negating Odors in New York Sewers
Saratoga County, located in the heart of eastern New York State, is divided into 19 towns, nine villages and two cities. From a sewage treatment perspective, that equates to 98 pump stations, approximately 300 miles of pipe and thousands of manholes, some in remote locations.
For more than a year, the Saratoga County Sewer District and its executive director, Dan Rourke, found themselves faced with multiple odor complaints from residential neighborhoods, parks and trails throughout different municipalities in the county. Since sewer odors can occasionally be an indication of a larger issue, such as a sewer main break, the county needed to thoroughly investigate each of these concerns. Sometimes this meant needing to call in personnel and pay costly overtime expenses.
Typically, after assessing the situation, their solution would be to respond with a chemical addition at the closest pump station to where they had received the odor complaints. Although this method did work to resolve a portion of the complaints the county was receiving, they were finding that some of the areas of concern were located too far away from a treatment plant for this particular method to be an effective recourse in eliminating the odors.
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In an attempt to resolve these areas of concern, the County needed to increase its effort in investigating the cause of the odor in order to find a more effective solution. “We found that low pressure sewer systems had caused some issues with long retention times prior to full build out, and whether it was an air release manhole or the manhole the low-pressure force main discharged too, the h2s gas would escape causing the odor issue,” says Rourke.
Sewer gas can contain hydrogen sulfide, which is almost always the leading cause for odor and can be detected easily with the nose in very low concentrations. Complaints of “rotten egg” or “sulfur” smells are contributed to hydrogen sulfide in sewer gas. Now knowing what they were up against, the county started looking into both passive and active methods of odor treatment including chemical addition by pumping and condensed potassium permanganate discs to sit in nearby wet wells or manholes. Unfortunately, the chemical addition would have been too expensive from both the capital expenditure and operating expense perspective, and the real issue seemed to occur once sewer gases were released through the manholes.
Not convinced that he had found the optimal solution yet, Rourke took his research online and discovered a product from Parson Environmental Products, Inc. called the Parson Odoreater Manhole Insert. This specially designed Manhole Insert, with the addition of a canister containing 20 lbs of activated carbon or non-impregnated, activated catalytic carbon, works to trap and store unpleasant hydrogen sulfide and methyl mercaptan odors. Purified air is then allowed to ventilate into the atmosphere through the canister lid. This concept seemed to be the passive solution the county was searching for and it would allow the odor problems to be resolved without a large capital expenditure.
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According to Rourke, “We priced similar style technologies, but the ease of installation and simple design allowed the pricing to come in such that Parson was the most economical choice.”
Saratoga County Sewer department decided to purchase and install Parson Odoreater Manhole Inserts in manholes throughout the county including manholes that were not responding to the chemical addition treatment. “The simplicity is the best feature” says Rourke. “They work really well in areas where the location may be somewhat remote, but is still heavily traveled by the public, such as walking and biking trails, public parks or utility easements near somebody’s rural back yard.”
The day after installation, crews revisited the manholes and noticed a substantial difference and lack of odor. So much so, that eventually odor complaints to the Saratoga County Sewer District went from just about weekly to not hearing any odor complaints for several months at a time. “After seven months, we still have not had to respond to the location where we would have the most issues,” Rourke states.
Today, the County has a preventative maintenance plan in place to keep odors under wraps instead of frequently dispatching personnel to address odor concerns. Maintenance to the inserts is minimal and only requires replacement of the carbon as necessary. Of the Parson Odoreater Manhole Inserts, Rourke also states, “They allow for a ‘public alarm’ style maintenance response, where when the odor complaint arises again, you know it is time to change the carbon and get an immediate reduction. This means no electrical instrumentation to worry about, no overflows of chemicals, or maintenance of mechanical systems.”
This method of odor control resolves the issues that the previous method of chemical addition could not address, especially in areas with manholes farthest away from the pump stations. While the county does not have Parson Odoreater Manhole Inserts installed in all of the manholes in their system, they do continue to add inserts to other affected manholes as new odor issues arise.
