What is inflow & infiltration?

When groundwater or stormwater enters dedicated sanitary sewer systems, inflow & infiltration is occurring. Most inflow & infiltration, or I&I, is caused by aging infrastructure that includes manholes and sewer pipes. While this may seem like a hopeless, inevitable problem, there are steps that communities can take to protect their wastewater systems.

Infiltration is when clean groundwater enters the sewer collection system. A great example of this is when heavy rain or snowmelt penetrates the ground and raises the groundwater level. That ground flow can infiltrate sewer pipes and manholes through cracks in the structure, missing or deteriorated gasket joints and leaky pipe penetrations. High water tables, or groundwater, is particularly common in coastal areas but also occurs in communities that are near lakes, rivers, ditches or wetlands.

While seeping groundwater infiltration may not sound like an immediate concern, it can become a costly long-term problem. For example, a single leaking manhole can allow thousands of gallons of clean water into the wastewater system daily. That clean groundwater must then be treated as dirty wastewater at the treatment plant. The longer infiltration issues are left unaddressed, the more costly it becomes to operate the wastewater treatment facility. (Read more about the efficiency of wastewater treatment facilities.)

Inflow is a more rapid flow of stormwater that enters the sewer collection system through defective manhole covers or frame seals, improperly connected roof or foundation drains, or combined sewer systems. Inflow is often the result of significant rainfall, snowfall, springs or snowmelt that contribute to excessive sewer flows. 

In an effective water and wastewater system, this large volume of stormwater will either drain into the ground or be routed to the nearest storm drains. Unfortunately, aging infrastructure often suffers from leaking manholes or connections that allow stormwater to drain into the wastewater system. Unlike slower infiltration, peak inflow during heavy storms can cause wastewater systems to backup and flood basements, culverts and creeks.

OBIC provides an effective solution to inflow & infiltration

Anatomy of a Manhole

Although they are a costly problem when left unaddressed, I&I issues are surprisingly easy to fix with OBIC. After years of experience rehabilitating thousands of manholes across the world, OBIC has discovered that the most common precast manhole infiltration problems occur at the joint area connecting the individual sections.

A typical joint configuration can be seen in the upper left of this drawing published by the National Precast Concrete Association. As you can see, a Ram-Nek® or similar gasket material is inserted into the joint during installation to make it watertight. As the systems age, that gasket material begins to deteriorate, allowing groundwater to infiltrate into the manhole.

OBIC manhole lining systems, the multi-layer OBIC Armor and the semi-structural, or fully structural system, are all designed to repair and prevent future I&I issues. These spray-applied polyurea systems tenaciously adhere to the substrate, protecting it from the harsh environments often found in wastewater systems.

No-dig manhole rehabilitation solutions offer a faster return on investment

OBIC manhole lining systems provide long-term solutions to costly I&I problems. Our no-dig manhole rehabilitation solutions mean that your systems can be back up and running at peak efficiency with minimal downtime. Not only does this provide you with a cost-effective solution, but you will also benefit from a fast return on your investment.

A manhole lining system that purports to stop I&I can only do so if it successfully adheres to the substrate. OBIC systems are formulated so that an effective combination of chemical and mechanical bonding mechanisms are present to assure adhesive strength and assure you of a successful I&I mitigation program.

Stop inflow & infiltration with OBIC

With OBIC you can stop inflow & Infiltration quickly and efficiently. Don’t trust a product with poor adhesion that looks good from the street but allows infiltration behind the liner. Trust the OBIC advantage. Contact us online or by phone at 419-633-3147 for more information or to schedule a free product demonstration.