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Chemical Sewers versus Combined Sewer Systems?

asked Jan 24 in Engineering by Toby McYang (370 points)
Please provide descriptions for Chemical Sewers and Combined Sewer Systems.

Thanks in advance!

2 Answers

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answered Jan 25 by antonjoh (2,870 points)

Chemical Sewers: They mean to collect acid, caustic or other chemical wastes that require neutralization or treatment prior to discharge to industrial sewers.

Combined Sewer Systems: The systems that combine two or more types of system (service) prior to any treatment.  The most common type of combined system is an Industrial and Storm Water Sewer System.  Combined systems should meet the most stringent requirements of all the individual sewer systems included in the combined system.

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answered Jan 27 by antonjoh (2,870 points)

Here are some additional terms that can help in the sewer/drainage area.

Catch Basins: Used to collect surface drainage and process wastes in individual drainage areas and to trap sediment at the point nearest the source.

Deferred Runoff: The controlled release of rainwater that has been held or impounded during the rainfall in a designated area such as a tank dike enclosure.

Drains: Small sewer inlets/connections (such as an open end pipe or fitting) discharging through a sealed connection to the sewer system from discrete sources, such as pump bases, equipment drips, low points of floors, etc., but not from outside surface drainage.

Hydraulic Seals: Used to prevent vapor emission out of inlets, and to isolate the various parts of a sewer system, preventing vapor travel and spread of fire or explosion.  Such seals shall be a minimum 6 in. (150 mm), unless otherwise specified.

Industrial or Oily Water Sewers: Collect process wastewater, and hydrocarbon/oil contaminated wastewater including rainwater or firewater runoff from areas normally subject to hydrocarbon/oil contamination and condensate/blowdown with hydrocarbon/oil or chemical contaminants.

Laterals: Sewer lines collecting the effluent from two or more sublaterals discharging to manholes on mains.

Mains: Sewer lines connecting manhole to manhole carrying combined effluent from laterals or sublaterals.

Manholes: Used in sewers as junction points and sediment traps, and to provide access for maintenance and inspection.

Open Channel Floor or Pavement Drains: Continuous troughs or trenches collecting surface drainage discharging to the sewer system.

Sanitary Sewers: Collect waste from the toilet facilities, lavatories, showers, and floor drains in rest, wash, and locker rooms.

Storm Water or Clean Water Sewers: Collect rain water runoff, firewater and condensate/blowdown that are not normally subject to hydrocarbon/oil, or toxic chemical contamination.

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