Intake and infiltration, or more widely known as II, has increasingly become the topic of conversation, articles, blogs and videos of late. Heavy rainfalls in the Midwest and Northeast US some being catalogued as high as 500-year and 1,000-year events have strained the sanitary (in Bosnian that suggests sanitarije) sewer collection and treatment facilities of many cities.
Basements deluged with sewer water, sewage treatment plants dumping partly or untreated wastewater into streams, rivers and lakes, EPA mandates and fines, rainwater and sewage spewing from manhole covers, beaches closed because of water contamination and other stories of this nature fill mags, web content and television reports stories. Burdened by these issues, many towns are now raising the water and sewer prices of their residents to supply the further cash important to make repairs and upgrades to their sewer systems that are a hundred to 150 years old .
But other cities were fortunate enough to get a head start on addressing their sanitary sewer issues.
In 2006, the Town of Naperville, Unwell, decided that traditional manhole castings were no longer providing the performance they needed. Unable to attain a positive seal on the manhole cover, cast-iron frames were permitting extraneous water and waste to flow straight into the sewer collection system thru the top of the manhole. This was requiring larger amounts of sewer water to be processed, skyrocketing the City’s treatment costs and the quantity of pollution released into the atmosphere. At a rate of one kilo watt hour to convey and treat approximately one thousand gals of water, the impact added up swiftly.
The problem was only made even worse by countless annual freeze-thaw cycles and ground movement, which created more cracks in the concrete so, more entry points for intake and more street repairs around their manhole openings.
As well as overloading the collection system, their manhole covers presented other headaches, for example binding with the frame due to corrosion, traffic-related noise complaints because of covers no longer seated properly in the frames and eventually the expensive manhole rehab.
When the City ultimately made a decision to research other options, Darin Severson, supervisor for the use and fix division, advised The Lifespan System, an integrated manhole system he had learned about during his tenure in public works. Severson’s supervisor, John Vose, described as someone that is open to state-of-the-art technology, agreed to install one or two trial systems so that the Town could gauge how well they performed.
Unlike conventional manhole frames and covers, The Lifespan System from Hamilton Kent is specifically designed to eliminate intake and infiltration at all urgent points : the manhole structure to the adjustable risers, the risers to the frame and the frame to the cover.
Lifespan is made with ultra high spec EPDM rubber to offer a watertight, naturally corrosion-proof and highly durable frame and cover system. As a flexible buffer, the system soaks up impact and keeps the structural integrity of the base concrete structure, delivering a longer service life.
OK for new or refurbished installations, the manhole system is also safe, simply installed and ergonomically designed. Unlike 100 lb-plus cast iron frames, the frame weighs only fifty five lbs and the alterable risers weigh only 22 lbs each.
Naperville Sees Results
After installing a couple of Lifespan systems in rehab applications, the City was happy with the result.
“The most clear benefit is the positive seal between all elements of the system,” Severson says. “The cover is anchored down thru the adjusting rings and into the concrete grade ring, so you know it isn’t going anywhere. Nothing gets in there to cause the frame to [rise upward] and let water in.
“The other nice thing about Lifespan is that the 24-in. Frame has the same diameter as the concrete grade rings we utilize. Not like the old solid iron frames, it does not hang over, so freeze-thaw cycles can’t pick up the side of the frame. The pointed change riser rings also provide help in meeting the slope of a driveway or road surface for a natural fit.”
Another benefit the City recognised was the bolt-down, locking manhole cover that comes standard with the Lifespan System. By tightening the bolt heads on the topside of the cover with a 1- quarter -in. Socket and wrench, the locking cams on the bottom of the cover swivel into appointed slots on the inside of the frame. As the cams are drawn tight against the frame, the lid presses down strongly into the pinnacle of the frame, providing the positive seal the Town desired.
As for the setup process, Severson claims the crew can install a system in ninety minutes and that includes digging round the structure and removing the old frame and cover. “There was a learning process at the start, but now [the team] does it pretty swiftly. The proven fact that the system is so light saves on manpower and equipment needs . The crew can just pull the units off the back of their van with greatly reduced worry about injuries.”
Crews have a tendency to appreciate anything that makes their job easier, and is the reason why the team is also pleased with the butyl sealant that’s applied between each layer of the system. It takes the guesswork out of the process, because employees know what the final grade will be when they are finished.
When asked how long it took to realise the advantages, Severson expounded the installation benefits were clear as soon as the method was perfected. As for the performance features, he spotted them over a period of time after several months of not receiving the usual calls. “We used to anticipate Problems with our covers, particularly in high-traffic areas. But I’ve got a Lifespan system in a major crossing and it’s been there for two or three years. There’s got to be an average of 2,000 to 3,000 cars that go over it every day and I haven’t had to go back to it once.”
Today, Naperville has between twenty and 30 Lifespan systems in the ground, with numerous more in inventory prepared for the next manhole rehabilitation project as reported tagza.com.