Effluent Diffuser Case Studies Summary

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1. Tuen Mun, Hong Kong Effluent diffusers improve water quality • Tuen Mun, Hong Kong • Brookings, Oregon • Viña del Mar, Chile • Des Moines River, Iowa • Enoree River, S.C. • Oostanaula River, Georgia In recent years, Hong Kong has undergone an aggressive plan to im- prove the water quality in Victoria Harbor and surrounding areas. One technology that was quickly embraced in wastewater treat- ment plants was the use of efflu- ent outfall lines with Tideflex ® Diffuser Valves. The Tideflex ® Valve was chosen for its ability to withstand extremely harsh conditions, and perform reliably for many years to come. Tideflex ® Valves prevent backflow of saltwater, sediment and debris back into the outfall. The valves also increase the jet velocity of effluent discharge, and create a flattened plume- shaped discharge that improves initial dilution and dispersion. Being able to mix the effluent discharge into ocean currents, and carry it away from the coast- line protects the island’s shores and harbor. The first installation was on the outfall line from the Northwest Kowloon Sewage Treatment Plant on Stonecutter’s Island. Two parallel outfall lines, each 2200 mm (80 inches) in diameter were run deep into the harbor, and terminated in three risers of the same diameter. Each riser was capped by three 1000 mm (39 inches) Tideflex ® Effluent Diffuser Valves. The largest and most recent installation was constructed as part of the Area 38 River Trade Terminal at Tuen Mun. Twin 1.5-meter (60 inches) concrete outfall lines were run to a length of 2070 meters (6790 feet). A third, emergency overflow line 800 meters long (2625 feet) was also run parallel to the main lines. Each main line features nine risers, and the emer- gency line features another three. Each riser is capped with a concrete “rosette” that houses six ports on the main lines, and four on the emergency line. All 120 ports are fitted with Tideflex ® Effluent Diffuser Valves, 300 mm (12 inches) on the main Red Valve Company Effluent Diffuser Case Studies lines, and 1050 mm (42 inches) on the overflow. This outfall line alone is designed to handle a peak flow of 6.6 cubic meters per sec- ond, 150 millions gallons per day! The Diffuser is located at 48 meters deep, and risers are spaced at 5m. Peak flow for this system is 6.6m 3 /sec. SEPTEMBER, 1999 ISSUE 1 Red Valve’s Effluent Diffuser Systems have been used on hundreds of municipal and industrial wastewater treatment systems across the globe. In many systems, the outfall line represents the only form of “treatment” being used. The unique properties of the Tideflex ® Effluent Diffuser Valve increases the efficiency of the system while protecting it from numerous potential problems, such as sand, sediment and saltwater intrusion, storm surges, and hydraulic transients. OCEAN OUTFALLS MEASURIT www.measurit.com

2. Brookings, Oregon Effluent diffusers stop clogging problems The City of Brookings Waste- water Treatment Plant on the Oregon coast discharges its final treated effluent to the ocean. The environment of the Pacific Northwest created many prob- lems for their existing outfall line, including saltwater, heavy debris, ocean tides, and cold temperatures. The existing system consisted only of fixed orifice ports drilled into the walls of a pipe. Clogging, headloss, and marine growth were major problems. Brown & Caldwell, the design engineers of the new 400-foot outfall line, utilized the Tideflex ® Effluent Diffuser Valve to meet the requirements of the city. The all-rubber construction of the valve will not rust or corrode, and the flexible nature of the valve does not allow hard marine growth to attach to the valves. “I suggested using the Tideflex ® Valve on the Brookings job because of its ability to prevent silting up and clogging. If there is no or low flow, the valve automatically closes. A significant added benefit is that, under low flow, the small orifice in the Tideflex ® tends to increase the velocity and improve the mix- ing energy of the diffuser” explained Bill James, Project Engineer. There was also a concern over damage to the risers because the outfall line was only in 15-20 feet of water. Submerged logs, rocks, and boat traffic posed a real problem to any fixed metal or plastic riser. To solve this problem, Red Valve supplied the diffuser valves with integral rubber elbows, reinforced with embedded wire. If hit by debris, the risers simply bend without breaking, and then return to their original position. After 8 years, the diffuser valves are still working well with no problems reported from clogging of backflow. Red Valve Effluent Diffusers are constructed entirely of rubber, making them ideal for marine environments such as this outfall in the Pacific Northwest. In the town of Viña del Mar, Chile, the local municipality decided upon an outfall line for final discharge of its treated effluent. A 1.2-meter diameter HDPE pipe was run 1.5km out into the Pacific Ocean at a depth of 48 meters. The pipe size was gradually reduced from 1.2m to 0.5m to maintain adequate pipe velocity of the discharge. The multiport diffuser was fitted with (20) 250mm Tideflex ® Effluent Diffuser Valves, spaced 5 meters apart. Each Diffuser valve was con- nected to the main line by a 90° elbow made from HDPE. This allowed a flanged diffuser valve to be used for added security, and allowed the discharge to be “aimed” in opposite directions for better dispersion. The original intent of the diffuser valves was to prevent saltwater and sediment from entering the pipe. Preventing sediment intrusion is important for keeping the line clear of buildup that would reduce the flow capacity of the line, and could eventually lead to clogging. Preventing salt- water from entering the pipe is important because saltwater has a higher specific gravity than the effluent and will lay on the bottom of the pipe. This creates a “saline wedge” that can block a number of ports and reduce the overall efficiency of the system. The pressure created by a gravity flow of effluent is often not enough to prevent saltwater from entering the line with fixed orifice ports. Purging saltwater from the line is also difficult, requiring near peak capacity flows. With Tideflex ® Diffuser Valves, saltwater is purged at very low flows. After the system was installed, an underwater inspection of the system revealed another advan- tage of the Tideflex ® Diffuser Valve. During inspection, the plant experienced a power failure that produced pressure transient waves that oscil lated in the outfall pipe. This caused the ports to experience a 10 meter reverse differential pressure that would normally pull huge amounts of Viña del Mar, Chile Diffuser valves prevent saltwater and sediment intrusion saltwater and debris into the line. The diffuser valves prevented any intrusion into the line. A video of the inspection is available from Red Valve for anyone who may be experiencing similar problems. (20) 250mm Tideflex ® Diffuser Valves are installed to prevent intrusion of saltwater and sediment into the header pipe. MEASURIT www.measurit.com

3. Cargill Inc. in Eddyville, Iowa is a corn wet-milling plant pro- ducing corn syrup, ethanol, and other corn-derived products. The plant has its own wastewater treatment facility that is shared by two other nearby industries. After biological treatment, the final effluent is discharged into the nearby Des Moines River. The Iowa DNR issued new water quality standards that were quite restrictive compared to the old standards. The new standards were applied to the Des Moines River below Cargill’s discharge point, and the IDNR determined that the ammonia levels in Cargill’s effluent discharge had to be reduced by 75%. Cargill commissioned a study to verify these assumptions, and found that only 17% of the river mixed with their effluent, compared to the 25% allowed for in the IDNR’s stream model. Cargill was faced with having to expand their treatment process to reduce the ammonia levels, at great cost. But Cargill’s design engineers along with the consult- ant, Howard R. Green, proposed using an outfall line with Tideflex ® Effluent Diffusers as an alterna- tive. They wanted a system that would cost less, be more reliable, require no maintenance, and could handle increased effluent discharge levels as the plant grew while staying in compliance with ever more stringent regulations. A computer model from Howard R. Green Engineering Consultants proved to the IDNR that an effluent diffuser system with Tideflex ® Diffuser Valves would solve the problem. Based on the performance of the diffuser sys- tem, the IDNR changed Cargill’s discharge scenario to allow 75% of the river to be used for mixing. This ensured that Cargill would be able to stay in compliance for years to come. A 24” outfall pipe was installed in three sections. Each selection was fitted with 6 flanged ports. Each port was fitted with 3 foot long plastic riser capped by a 4” Tideflex ® Diffuser Valve. The pipe was encased in cement and backfilled so that only the diffuser valves protruded from the riverbed. (44) 4 inch Tideflex ® Diffuser Valves installed on this award-winning diffuser system for a food processing plant discharging to the Des Moines River. Ocean outfalls are not the only place where Red Valve’s Tideflex ® Effluent Diffuser Valves are used. Inland wastewater treatment plants and industrial plants discharge effluent to rivers, lakes, and streams. Inland waterways are often more sensitive to discharges because of the smaller volume of water, and the proximity to residential population. Any negative impact on the environment is immediately apparent. Outfalls to inland waterways often have to contend with strong currents, boat traffic, debris, and flooding as well. Des Moines River, Iowa Industrial plant meets new water quality standards with effluent diffusers Enoree River, South Carolina Diffuser meets toxic limits in shallow river Taylor’s Wastewater Treatment Plant in South Carolina used to discharge its effluent to the nearby Enoree River at a single-point. This discharge was quite concen- trated and periodically exceeded the permissible toxic limits for the plant. The decision was made to add an outfall line that would spread the discharge out across the river and minimize the toxic impact. The river was not very deep, only 6 feet on average, and debris floating downstream could damage exposed pipe or risers. To reduce the toxic load, the discharge would have to be quickly dispersed into the river and immediately diluted. Fixed orifices did not provide this level of dilution, and were prone to clogging. The Tideflex ® Effluent Diffuser Valve provided the ideal solution. (12) 150 mm Tideflex ® Effluent Diffuser Valves were spaced across the length of an outfall pipe to evenly spread out the dis- charge. Each valve was fabricated with a 1-meter rubber riser so that the entire assembly could be buried beneath the riverbed, with only the diffuser valves protruding from the bottom. The valves were also angled at 30° from hor- izontal and the bills of the valves were oriented horizontally to help dispersion in the shallow water. The treatment plant is now in compliance with toxicity limits and does not have to worry about damage to the system from debris. In fact, S.C., realiz- ing the enhancement of initial dilution with diffusers, will remove the requirement to perform acute toxicity testing if a diffuser is installed on an outfall. Tideflex ® with integral rubber risers prevent backflow and prevent damage from floating debris INLAND OUTFALLS MEASURIT www.measurit.com

4. Oostanaula River, Georgia Effluent diffuser eliminates foaming and discoloration problems Not all Tideflex ® Effluent Diffuser Systems are used just to improve water quality. Power plants for example, have used effluent diffuser for many years to reduce the environmental impact of discharging hot water from cooling towers. In Calhoun Georgia, the municipal waste- water treatment plant receives heavy loads from the local textile industry. The concentration of dyes in the effluent would badly discolor the Oostanaula River at the point of discharge. To make matters worse, the outfall line discharged onto a series of riprap embankments, slowly cascading down into the river, creating a tremendous amount of foam. While not harmful to the envir- onment, the foam and discolor- ation were the cause of many complaints from the residents of Calhoun because the river is the focal point of a large recreational area. The city had to stop the foam and disperse the effluent to reduce the discoloration of the river. The solution was to use a series of wells to lower the discharge point below the surface of the river, and install an effluent out- fall line fitted with (18) individual ports. Each port was provided with a flange to allow connection of an 8 inch Tideflex ® Diffuser Valve. The valves were supplied from Red Valve with integral 90° rubber elbows to raise the valves above the riverbed and point the discharge downstream. The dif- fuser has completely eliminated the foaming problem, and reduced the discoloration to acceptable limits. (18) 8” Tideflex ® Diffuser Valves with integral 90° wire-reinforced rubber elbows were used on this outfall design to eliminate discoloration and foaming concerns raised by the public. Red Valve Company • 700 North Bell Ave., P.O. Box 548, Carnegie, PA 15106-0548 • Phone: 412 279-0044 • Fax: 412 279-7878 e-mail: valves@redvalve.com • website: www.redvalve.com P Prevent intrusion of debris, sediment, saltwater and aquatic life P Provide proven long-term, maintenance-free service life P Enhance jet velocity P Improve initial dilution P Provide a more uniform flow distribution across ports P Purge saltwater at extremely low flows during start-up Tideflex ® Diffuser Valves: Problem Solution Contact Mike Duer, P.E. at Red Valve to discuss your specific diffuser project. 412 279-0044 , ext. 233 QUICK FAX FORM • 412 279-3180 ARE YOU CURRENTLY DESIGNING AN OUTFALL PROJECT? Project Name o Existing o New Please send me literature on the following: o Effluent Diffuser Brochure o Diffuser Video Name Title Telephone Company Address City State Zip 35D with 45° elbow 35D with 90° elbow MEASURIT www.measurit.com


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