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What goes up must come down. But what goes down the sewer should not come up into our basements, streets, or streams. Few Americans give much thought to the fate of the infectious wastes we flush down the toilet or the toxic wastes we pour down the drain. Most assume that raw sewage from homes, offices, and industries is kept at a safe distance from people and the environment. Few realize that treated waste is released back into our waterways, making millions of Americans sick.
The nations million-mile network of sewage collection pipes10 is designed to safely carry roughly 50 trillion gallons of raw sewage daily11 to about 20,000 sewage treatment plants.12 In 2001, however, the Environmental Protection Agency estimated there were 40,000 sanitary sewer overflows (SSO) and 400,000 backups of untreated sewage into basements.13
Small wonder. Sewage pipes, many between 50 and 100 years old,14 can develop cracks or joint openings from the weight and vibration of roads, soil, and structures above them, and from the corrosive actions of water, bacteria and chemicals from inside and out. Opportunistic plant roots widen these openings, allowing raw sewage to escape into groundwater. Rainwater entering the pipes through cracks and openings, or from illegal connections, can overwhelm the capacity of the system, forcing raw sewage to purge through manholes into streets and streams, back up into basements, or otherwise bypass treatment plants. Even during dry weather, clogged, malfunctioning, or overloaded systems can discharge raw sewage.
Older municipalities, predominantly in the Northeast and the Great Lakes area, have sewage collection systems that were designed to carry both sewage and stormwater runoff. When the combined volume of sewage and stormwater overwhelm the capacity of these systems, combined sewer overflows (CSO), which contain a mix of untreated sewage and stormwater, automatically bypass treatment plants. The EPA estimates that 1.3 trillion gallons of raw sewage are dumped by CSOs each year,15 putting communities with CSOs at risk from high concentrations of microbial pollutants.16
When waterways are used by multiple communities, as is the case for most of the interior portions of the United States, sewage overflows can put downstream users at risk. The Missouri River, for instance, is the source of drinking water for some of the major cities of the Midwest. Yet the distance between wastewater discharges and water supply intakes is often very short. In Michigan, for example, the distance between wastewater discharge points and water supply intakes is often less than 5 miles. The case is similar for the Ohio and Missouri rivers.17 Thus, it is essential that the sewage collection and treatment systems operate properly to avoid exposing people to human pathogens.
About The Septic Tank ShopWe have been installing repairing and selling septic tanks and sewage treatment systems for many years now. For free advice please contact us or visit http://www.theseptictankshop.co.uk/Sewage_Treatment_Plants
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