Case Studies - Summer 2021

Case Studies - Summer 2021

Process successful in rehabilitating deteriorated manholes

Problem:

Hydrogen sulfide is a corrosive compound which, over time and combined with heavy inflow and infiltration, deteriorates manholes. That was the case for several manholes in Richmond, California.

Solution:

Before the epoxy liner could be installed, extensive surface preparation and repairs were needed. The entire surface of each wall was resurfaced using hydraulic cement. In manholes where bricks were missing, they were replaced by filling in the areas with micro-silica cement. Furthermore, any severe leaks were injected with grout. At this point, H & R Underground was then ready to apply Epoxytec’s CPP Sprayliner. Using a Graco XP70 plural pump set at a ratio of 1:1, it sprayed CPP Sprayliner at 150 mils thick.

Result: In total, seven manholes were rehabilitated over the period of one week. The expertise of H & R Underground, specifically its attention to detail in addressing each manhole’s individual needs, allowed for successful rehabilitation in a timely manner.

877-463-7699; www.epoxytec.com


Inside drop system eliminates costly excavation

Problem:

Sewer drops have traditionally been constructed outside of the manhole, a technique that has proven troublesome over time. Outside drops are expensive to construct, requiring excavation down to the manhole invert elevation. Outside drops are difficult to access for inspection and cleaning, leaving them prone to clogging and failure. A failed outside drop, such as one recently encountered by a municipal utility crew in a Midwestern city, can lead to infiltration into the manhole. 

Solution:

The RELINER/Duran Inside Drop System was designed to control flow using simple, cost-effective components inside the manhole for easy installation. The system consists of a marine-grade fiberglass drop bowl that is bolted to the manhole wall. Stainless steel pipe support brackets are used to attach the drop pipe to the manhole wall. The drop bowl does not touch the incoming pipe and protrudes minimally into the structure. A flexible coupler is used to connect the drop pipe to the drop bowl, and a bend is installed at the pipe base in the manhole invert. An optional force line hood is available for high-velocity applications. 

Result: The system is easy to install and allows the drop to be cleaned and inspected from above. The system can be used for main line, service connection and wet well drops, and it worked effectively in the Midwestern city. They accommodate internal drops ranging from 4 to 24 inches in diameter in a variety of different structure sizes. 

800-508-6001; www.reliner.com


Manhole risers a good fit for town prone to flooding 

Problem:

Fairhope is a small city, just 15,000 residents, situated on the cliffs and shoreline of Mobile Bay in Alabama’s Gulf Coast. Infrastructure maintenance can be a challenge here for all the usual reasons, and one unusual one – the city has a history of devastation and flooding by hurricane, including Hurricane Frederic in 1979 and Hurricane Katrina in 2005. But the city doesn’t have a problem keeping manholes at grade after roadway resurfacing projects — not in recent years anyway.

Solution:

For 15 years, Fairhope has been specifying the American Highway Products Pivoted Turnbuckle Manhole Riser. The risers are sturdy, flexible rings made of galvanized steel, and they can be ordered in precise diameters to match any manhole, and in precise (increments as fine as a 1/4-inch) thicknesses to precisely match paving lifts. The “pivoting turnbuckle” is an adjustable linkage that allows the risers to be set loosely in an original utility rim, then expanded with a Phillips screwdriver (used as a lever) to seat tightly and securely.

Result: At-grade risers are better for roads in many ways, compared to concrete ring replacement. They don’t set low, so water doesn’t collect around the manhole lid causing excessive infiltration, and they don’t set high, so vehicle tires don’t jar the lid and rim continually. And since risers are usually set just before paving runs, the newly raised manhole is surrounded by new, contiguous pavement, and that prevents water and freeze/thaw damage in the pavement around the manhole. 

888-272-2397; www.ahp1.com 


Leak detection investment leads to significant decrease in non-revenue water loss

Problem:

Privately owned and over 200 years old, the Belle Vernon Municipal Authority serves a population of just over 6,000 residents. It encompasses the Pennsylvania regions of Belle Vernon, North Belle Vernon, and parts of Rostraver and Washington townships. The water plant was decommissioned, and Belle Vernon Municipal Authority began purchasing water from another municipal authority in September of 2016. The Belle Vernon Municipal Authority services an infrastructure comprised of steel, cast iron and plastic with portions dating over 100 years old. Given the aging infrastructure, it is not surprising it was faced with non-revenue water loss as high as 50% with flows as high as 0.700 mgd. The water bills coming from the authority it was purchasing its water from were as high as $65,000 per month.

Solution:

With the help of 540 Technologies, Belle Vernon Municipal Authority decided to address its non-revenue water loss through leak detection and invested in two key leak detection devices from Fluid Conservation Systems. Superintendent Guy Kruppa and Leak Detection Lead Foreman Rich Saxberg started with 55 Permalog+ units to cover the majority of the service area. When paired with the FCS Patroller device, these easily deployable, acoustic logger units continuously monitor leakage and transmit an “alarm” when a potential leak is located. In February of 2020, they added to their inventory by also purchasing the TriCorr Touch Pro, an easy-to-use, robust correlator designed to provide the best performance in traditionally difficult leak detection conditions such as plastic or large-diameter pipes.

Result: By utilizing these devices, Belle Vernon has decreased its non-revenue water loss to 13%, which saved it over $36,000 by the end of 2020’s fourth quarter. Its daily flows are now averaging .326 to .360 mgd and its water bills are now averaging $22,000 a month. Following its AWWA Water Audit, the authority is focused on apparent losses, replacing old meters and mapping the assets in the water system through GIS. 

513-831-9335; www.fluidconservation.com


Satellite-communication network enables quick emergency response

Problem:

After a drunk driver collided with two power poles in El Segundo, California, over 4,000 residents experienced power outages. Not only were residents out of power, but seven sewer lift stations were off grid. A major sewer spill in the nearby Pacific Ocean could lead to an environmental disaster. 

Solution:

SmartCover alerted El Segundo sewer operators with level measurements. These alarms allowed the city to prioritize which lift stations were critical for response. Generators and emergency pumps were then allocated to the most-needed stations. Shortly after power was temporarily restored, on-call employees were notified that another outage was detected. Other segments of the electrical distribution system were overloaded and left nonfunctional. Field crews had no access to the internet due to the power outage. Decisively, they used their smartphones to their advantage, accessing SmartCover’s website to track water levels at the stations. In response, three staff members shuttled generators from station to station. The online satellite-based monitoring system enabled the employees to see which stations were in need of immediate support.

Result: The strategic decision to invest and implement SmartCover technology using a satellite-communication network enabled the city to effectively respond to an unexpected infrastructure emergency, successfully restore power to residents and back up its sewer lift stations. 

760-291-1980; www.smartcoversystems.com


Large water system controller seeks level measurement solution

Problem:

The largest water system controller in Melbourne, Australia, came to Hawk Measurement Systems to help provide a level measurement solution that would assist with the water system’s emergency shutoff valves. The application consisted of a tank filled with hydraulic oil (bottom of tank) and nitrogen (top of tank). The nitrogen is inserted at the top of the tank to push the oil in the line and keep the hydraulic actuator functioning properly. The system acts as an accumulator with capacity to shut off valves in the event of an emergency shutdown. As the oil level in the accumulator drops, so does the pressure. Nitrogen in the tank is initially set up with the typical operational level of hydraulic oil systems. As the system is closed, there is no need to add more nitrogen afterward.

Solution:

Hawk Measurement Systems’ Magnetic Level Gauge with Chamber along with the Centurion Guided Radar Level Transmitter was the level measurement solution to this difficult application. The level transmitters were installed to measure the level of hydraulic oil in the chambers, and they also supplied the analog output. The magnetic level gauge was selected because it provides real-time measurement for level and interface. The transmitter was selected because it’s suitable for level interface measurement of liquids, sludge, powders and granules. The technology is not affected by pressure, temperature, viscosity, vacuum, foam, changes in the dielectric constant or coating of the probe.

Result: The water system controller was extremely satisfied with the outcome and the technologies and services provided. 

888-429-5538; www.hawkmeasurement.com 



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