How Do Sewer Lines Work?
Sewers have gone hand in hand with human civilization for centuries. They were used in ancient cultures as far back as 3,500 years ago. Both the ancient Greeks and Romans created extensive sewer systems. Today, sewer lines remain a vital part of cities and communities, removing dangerous waste and helping to maintain public health. Does this Spark an idea?
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Primary
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Two primary systems, the sanitary system and the wastewater system, carry water and waste materials from the point of origin, such as homes or buildings, to the termination point, such as treatment plants or rivers. The sanitary system disposes of raw sewage while the wastewater system eliminates excess water from storms or heavy rains. Both systems depend on a network of sewer lines to move the waste to its point of disposal.
Materials
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Sewer pipes need to be built from strong materials to withstand the constant pressures of both moving large amounts of waste and the structural forces that result from their burial underground. Pipes with smaller diameters are typically made from vitrified clay, asbestos cement, or plastic. For pipes with larger diameters, concrete is often used. The joints between pipe sections must remain tightly sealed to preclude any leakage into the surrounding soil.
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Placement
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The placement of pipes in a network depends on the local topography since designers of sewer systems try to capture the forces of gravity whenever possible. Gravity allows the waste to run downhill without any outside energy needed to stimulate its flow. The slope of the pipes must ensure that the waste flows at a moderate, steady rate. When downhill placement proves impossible for any reason, a pumping system comes into effect, forcing the waste to a termination point or to another downhill pipe.
Manhole
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Access points, called manholes, allow workers to access the sewer lines to make spot checks on the flow rate and perform other necessary maintenance. Manholes typically have a cylindrical shape and are often made of materials such as brick or concrete. Workers enter the manhole by means of a round, cast iron cover that can weigh as much as much as 300 pounds in some instances. The cover must fit tightly over the hole to keep out surface water.
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References
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