What do our sanitary and storm sewers do?
The main function of a sanitary sewer system is to convey waste water and solid waste from homes, businesses and industries through a series of underground pipes and manholes to waste water treatment plants where it is cleaned and returned to the environment. The storm sewer system collects rain and melting snow, referred to as runoff, in catch basins set alongside roadways. The runoff then flows thru pipes and manholes connected much like the sanitary system. This water does not require any treatment and is diverted directly to local streams and waterways.
What are some of the Characteristics of these systems?
While most of the sanitary sewer system utilizes gravity to convey the waste water, there are some cases where it is pumped from low points or low lying areas up to higher elevations where it can then utilize gravity again to convey the waste to various treatment plants. Manholes are positioned in the system to provide access to the buried pipelines for regular maintenance, repairs and flushing. Manholes are also used whenever there is a change in pipe sizes, change in the direction of the sewer line, or a change in elevation. In the storm sewer system, water or runoff is conveyed much the same way as in the sanitary system, but again no treatment is required.
There is also a third type of sewer system called a combined sewer. In this system, one pipe carries both sanitary waste water and storm runoff together. The City of Buffalo is served by a combined system that was built many years ago. In today’s modern world, the sanitary and storm sewers are designed as two separate systems. The problem with a combined sewer system is that, during large rain events, the runoff can exceed the capacity of the sewer. When this occurs, the excess flow is sometimes diverted to large holding tanks called Overflow Retention Facilities (ORF). These facilities store the excess waste water, and when the rain or melting event is over, it is reintroduced into the system and flows on to the treatment plant for processing. In some systems, these excessive flows unfortunately are overflowed to nearby waterways. These overflows are known as combined sewer overflows (CSO’s). Today, laws like the Federal Clean Water Act and agencies like the Environmental Protection Agency exist to help communities around the country with their plans to improve or replace these antiquated systems. The goal of these agencies working together with our communities is to help provide more effective and economical ways to treat waste and to protect our environment and waterways for everyone to enjoy.
To keep the sanitary and storm sewers flowing properly, crews from the City of Buffalo and Erie County continually monitor the current conditions of the sewer system either manually or through the use of automated computer systems. Today there are also new methods for inspecting and pinpointing leaks and collapses in old sewers mains, video equipment small enough to travel inside the pipe can see and record the exact location of problems. Regularly scheduled cleaning of the sewer system is done using high pressure flushing equipment. Older sections of these sewer systems are replaced each year as a result of both planned renovation and expansions and because of emergency repairs. Today there are many new methods to replace and repair old leaking sewers. Some repairs can even be done without any digging and with minimal disruption to service or the surrounding community. Erie County is continually looking for ways to improve service to the customer and protect the abundant natural resources we enjoy here in Western New York.