A major source of infiltration occurs at the top portion of the manhole where the metal casting connects to the main structure. The elements begin to effect this section of the structure over time, creating an endless amount of issues. Our best solution is to install Flex Seal Utility Sealant a product specifically designed for this application. Its 800% elongation makes it a perfect product to hold up in the winter when the frost sets in. If thats not good enough it creates a water tight seal on the inside of the grade rings to prevent erosion from the outside of the structure. Along with 800 percent elongation and the water tight seal Flex Seal protects concrete from concretes worst enemy HS2 gasses.