10/21/1996 Meeting Minutes - Laserfiche WebLink

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d - - - a .? ?w NRegional Sewer District 3826 Euclid Avenue • Cleveland, Ohio 44115-2504 216 • 881 • 6600 FAX: 216 • 881 • 9709 ANSWERS TO COMMONLY-ASKED OUESTIONS ABOUT --? ODORS AND ODOR CONTROL Q: Why are t/:ere odvrs coming from the tunnels? A: The type of tunnel system built by the District is a fairly new concept, with sanitary flows dropped upwards of 250 feet through widely spaced shafts. Once the system was started up, " we found that air from the surface was drawn into the tunnel along with-the wastewater, causing the tunnel to be under a slight positive pressure. Depending on many factors, such as time of day, temperature, amount of flow, etc., this pressure may be released at downstream points, and the escaping air carries with it the odor of the sewage in the tunnel. Q: Are the gases coming from the tunnel dan;erous? A: The District has conducted comprehensive air monitoring at each site where odor complaints have been registered. Results of this monitoring have shown the only problem to be associated with low levels of hydrogen sulfide gas. Hydrogen sulfide can be detected by humans at e:ctremely low concentration, and no health effects have ever been noted at the Ievels observed neaz the tunnels. Q: What is being done to control the odors? A: Upon learning of the problem in 1995, the District installed an air scrubber at the corner of Beech Hill and Bonnieview Roads. This device has worked well, but is only suitable for short-term use due to the need to constantiy supply it with chemicals and its aesthetic impacts. We have worked with Cuyahoga County to alter the cycles of County-operated pumping stations which route flow to our tunnels in order to keep this sewage fresher and to reduce odors associated with any air that does escape from our system. In azeas where odors persisted, we have also plugged and sealed several manhole and access shaft covers. Construction began in the summer of 1996 on permanent odor control devices at several locations, including the comer of Beech Hill and Wilson Mills. The basic process being installed is known as biofiltration, which acts to destroy odors (not mask or cover up) using a natural process. There will be no chemicals required, no above-ground structures, and only a single piece of inechanical equipment in the form of a fan which will be used to draw air out of the tunnel and route it to treatrnent. Q: What will t1:e biofilter at Beech Sill and Wilson Mills look like? A: The main part of the biofilter will be the treatrnent bed, which will be about 85 feet long and 25 feet wide. This bed will consist of a bottom layer of rounded stone overlain by a mixture of shredded bark, woodchips, and well-stabilized compost. Air will be distributed to the bottom of this mixture, and will be treated as it passes upwazds. The bed will be ` r surrounded by a variable height landscaped earthen berm. All other elements of the facility will be housed in underground vaults, and the only items visible on the surface will be the berm, the top of the bed, and the concrete pads and vents over the vaults. The mission of the Northeast Ohio Regiona! SewerDisfrictis fo enhance public health and welfare fhrough the efficienf, cost- effective conveyance and treatmeni of wastewater. This is accomplished 6y an organization dedicated to professiona/ism, fairness and consistency that anficipafes and responds to fhe changing environmenfa/ needs of the community.