For those that work in wastewater, the concrete grade ring is a familiar foe. Weighing anywhere from 90lbs up to 300+lbs, this ubiquitous gray monster is prone to breaking down and breaking backs. Time to install and backfill is counted in hours and the need to replace the rings can be yearly in high traffic areas.
The Ladtech System
Made from 100% recycled plastic in the USA, the HDPE Ladtech grade ring is the concrete grade ring's lightweight alternative that adds strength and durability while greatly reducing time required for installation and maintenance. While ASTM standards cover the storm and sanitation infrastructure, it does not address the chimney section. Without specific ASTM guidelines regarding the specifications for the grade rings, the Ladtech rings were designed using the most stringent AASHTO standard: the bridge standard. The bridge standard addresses the effects of dead load and impact load, as well as the effects saline (such as H2S), extreme heat and extreme cold can have on a structure. The result is a HDPE grade ring system with a life expectancy of 75-100 years, even in heavy traffic. After 21 years, Ladtech rings can now be found installed as close as the US, Mexico, and Canada and as far away as the Turkey and Australia. There are over 4,000,000+ rings in service currently, all with the same 5 year warranty that was instituted with the first installation in 1996.
Dead Load. The Ladtech ring was independently tested to meet the AASHTO H20 standard for dead load, which is 25,250 lbs. At 84,500 lbs, with the Ladtech rings showing no sign of damage, the cast iron fitting used for the test failed.
Impact Load. Although the AASHTO standard for testing is a H20 wheel load, the Ladtech rings were tested at a H25 wheel load at a 3/4 inch drop. After 1,005,334 cycles, the Ladtech rings showed zero fatigue cracking or deformation. In contrast, concrete grade rings begin to show cracking after only 70,000 cycles at a H20 wheel load. Concrete grade rings are built for, and tested for, a dead load, which is what leads to the frequent rehabs that are required when the chimney starts to break down.
Saline. Mixing Hydrogen Sulfide gas and water results in sulfuric acid. It's this potent mixture that accounts for the most corrosive damage to a wastewater system, including the chimney. Given time, H2S will eat through almost anything at a fairly rapid pace. Except HDPE. The ASTM standard for H2S resistance is a mere 48 hours. The Ladtech rings were tested for over 168 hours and showed no degradation. In fact, HDPE is so resistant to chemical degradation that it the most commonly used container to ship caustic materials.
Heat and Cold. The asphalt ASTM standard is between 265°F and 280°F. The Ladtech rings were tested for heat at 287°F and cold at -20°F. In both cases, the rings passed the test easily. In fact the rings actually became stronger in the colder temperatures.
Saving your Resources
Be it safety concerns, budget concerns, or environmental concerns, in the end, the durability designed into the Ladtech System is geared towards protecting your resources. The lighter weight of the Ladtech rings means a significant reduction in the chance of injury from manual materials handling (MMH). A 4" concrete grade ring weighs 180 lbs on average while a 4" Ladtech ring weighs a mere 12 lbs. This also significantly reduces the time it takes for installation. The installation time with concrete is over an hour and a half, plus backfill, and is considered a Confined Space Entry. Installation of the Ladtech System typically takes 30 minutes or less with immediate backfill. In addition, Ladtech is a mortarless installation, so there's no Confined Space Entry. The core costs of a manhole rehab/installation, labor and equipment, plus extras such as traffic control, are effectively reduced by two-thirds.
In addition to the immediate cost-savings, the Ladtech System has a positive financial effect over the course of time. Many wastewater and sanitation systems are subject to overflow issues due to events such as heavy rains, seasonal monsoonal floods, or spring thaw. Fifty to seventy percent of total I&I comes from the manhole structure itself, with an estimated 60% coming directly from the chimney section. Even for the systems that can handle significant I&I, this influx of water to the system still results in higher costs to process at a treatment plant. Many municipalities and agencies address I&I at the top level with a gasketed product such as the Pamrex manhole cover, but continue to use concrete grade rings in the chimney. Making matters worse, concrete grade rings are often reused long after they've shown signs of damage such as cracking. Ladtech's durability, together with the sealant used in installation, eliminates the I&I associated with the chimney section.
Ladtech grade rings are now available from Famcon in sizes ranging from 24" to 34" clear opening. Contact us for pricing or to schedule a free demo of the Ladtech System in your worst manhole.