Guarantees no groundwater contamination

Each year, for every person connected to a sewer system, at least 33,000 litres of groundwater enter into the sewer and becomes polluted with sewage. The 100% sealed, monolithic SBS™ pipe network prevents groundwater from entering sewer systems and from diluting flowing sewage wastes. No storm water inflow or groundwater infiltration means that only household liquid waste arrives at the treatment plant; inflow/infiltration (I/I) create surge flows which the plants are not designed for, resulting in operators bypassing the treatment plant and dumping raw sewage into receiving waters to save the sewage treatment plant equipment. By maintaining sewage flows that are consistent and have no I/I, thus preventing treatment plant bypasses during storm events, the SBS™ system's effluent flows are up to 50% lower in volume, have lower impact on the treatment plant, and up to twice as many equivalent connections can be processed at the sewage treatment facility for the same capacity as the historic system. Prevention of I/I flows is a responsible and environmentally sound sewer design practice.

Groundwater Infiltration
(photo courtesy of Niagara Region)

Issues of I/I in Historic Sewers

Groundwater infiltration into sewer networks is a key problem with historic gravity sewer systems; leaks at gaskets, at manholes and from damaged pipes are the norm. The net result is a significantly larger flow for the wastewater treatment facility to process, requiring more energy, nutrients and chemicals to treat the wastewater that's diluted with unnecessarily transferred groundwater. The Clearford SBS™ system utilizes all welded high density polyethylene (HDPE) materials and has no gasketted joints or connections where failures can occur.

Inflow/infiltration into historic sewers is the largest factor affecting the malfunctioning of downstream sewage treatment plants. American Rivers urged the U.S. Environmental Protection Agency to develop guidelines to prevent sewage bypasses which occur during storm events as water inflows and infiltrates into the sewers, increasing the flow by multiple amounts and then hammers the treatment plant with a large, untreatable volume of diluted sewage. Treatment plant bypasses associated with infiltration from rainfall events and snow melt occurrences are common incidents. The elimination of infiltration as it affects sewer systems is a major and continuing issue with municipal administrators and system operators.

I/I Solutions with the SBS™

The Small Bore Sewer™ system is designed with continuous piping connected by welded joints in the mains and laterals; maintenance holes are comprised of vertical extensions of the main piping system, with no joints. Clarifier tanks are connected to the laterals with leak-free, fused connections at the inlet and outlet locations of the tank. The use of 100+ psi pressure rated high density polyethylene for the mains, laterals, and maintenance holes, combined with the high-quality coupling system at the certified leak-free clarifiers will provide for a collection system with zero infiltration.

With the SBS™, compared to historic technology, clean groundwater will not become contaminated with sewage in the collection system, and will no longer be treated at the wastewater treatment plant as if it were sewage – then returned to the environment in a less pure state. The use of lower total design flows with zero infiltration will decrease the sewer main pipe sizing, as well as minimize the design and size of downstream infrastructure (pumping stations, force mains and treatment centres). Sewage treatment plants can be downsized because of the lower, infiltration-less flow rates; more connections can be added with the SBS™ collection system than with the historic system, for the same plant capacity.