Sanitary Sewer and Septic Tank Quiz

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Questions and Answers

What is the minimum height that the side walls of a septic tank must extend above the liquid depth?

150 mm

300 mm

200 mm

228.6 mm (correct)

What material is prohibited for use in partitions or baffles between compartments in a septic tank?

Wood (correct)

Concrete

Metals

Plastic

What is the minimum required size for the inverted fitting installed in the inlet compartment side of the baffle?

120 mm

150 mm

75 mm

104.6 mm (correct)

How much earth load must septic tank covers be capable of supporting?

144 kPa Signup and view all the answers

What defines a sanitary sewer?

Carries regular sanitary wastes only Signup and view all the answers

What is the minimum depth at which a sanitary sewer should be built?

3 meters Signup and view all the answers

What is required for the vent area of inlet and outlet pipe fittings in relation to the house sewer?

Must equal the cross-sectional area of the house sewer Signup and view all the answers

What is the term used for a public sewage system operated and maintained by the government?

Public Sewer Line Signup and view all the answers

What is the typical diameter range of tributary sewers?

0.60 to 1.20 meters Signup and view all the answers

At what depth do intercepting sewers typically terminate?

4 to 30 meters Signup and view all the answers

What is a requirement for drainage pipes of all buildings?

They must connect to the public sewer when available. Signup and view all the answers

Which of the following is unlawful to discharge into public sewers?

Ashes, cinders, and solids Signup and view all the answers

What defines the minimum size of any building sewer?

The total number of fixture units drained Signup and view all the answers

What is the maximum distance from any proposed building a public sewer may be before it is considered unavailable?

61 meters Signup and view all the answers

What should not discharge into any excreta drainage system?

Commercial food waste Signup and view all the answers

What is the slope angle at which intercepting sewers are typically laid?

1:50 or 2% Signup and view all the answers

What is the primary disadvantage of a privy?

It contaminates the water supply. Signup and view all the answers

What percentage of suspended solids are typically removed during the retention period in a septic tank?

60%-70% Signup and view all the answers

What are the two main processes combined in a septic tank?

Sedimentation and anaerobic decomposition Signup and view all the answers

What is the semi-liquid substance formed at the bottom of a septic tank called?

Sludge Signup and view all the answers

Which type of bacteria thrives in the presence of oxygen?

Aerobes Signup and view all the answers

What is the purpose of the open-jointed sub-surface piping in a septic tank system?

To allow liquids to discharge into the soil Signup and view all the answers

Which type of bacteria is responsible for the digestion of organic matter in a septic tank?

Aerobic, anaerobic, and facultative bacteria Signup and view all the answers

What is a cesspool primarily constructed for?

To store raw sewage Signup and view all the answers

What is the minimum diameter allowed for a building sewer?

150 mm Signup and view all the answers

What is the minimum slope required for building sewers?

2% Signup and view all the answers

Under what circumstances can sewers with diameters of 102 mm and 152 mm have a slope of 1%?

When impractical due to various construction factors Signup and view all the answers

What is the minimum distance a building sewer must be from any building foundation?

0.6 m Signup and view all the answers

What is the required distance of a building sewer from water supply wells?

15.2 m Signup and view all the answers

What is the minimum clearance requirement for water pipes above sewer pipes?

0.3 m Signup and view all the answers

What must be the horizontal distance between a water pipe laid in the same trench as a sewer pipe?

0.3 m Signup and view all the answers

Which component is not generally considered part of a sewage treatment plant (STP)?

High-pressure water jet Signup and view all the answers

What is an air break in a drainage system?

The physical separation between a waste pipe and an indirect waste receptor Signup and view all the answers

Which condition describes back siphonage?

The reverse flow of wastewater into a clean water system Signup and view all the answers

What is the purpose of a septic tank?

To retain solids, digest organic matter, and allow liquid to discharge into the soil Signup and view all the answers

Which term best describes a public sewer?

A sewer accessible by all property owners within a jurisdiction Signup and view all the answers

What is meant by back pressure in a drainage system?

Pressure within the system that exceeds atmospheric pressure Signup and view all the answers

What is sludge in the context of a septic tank?

Solid organic matter that settles at the bottom Signup and view all the answers

What is a branch interval in plumbing?

The section of the soil or waste stack connecting branches from one storey Signup and view all the answers

What does the term scum refer to in wastewater treatment?

The lighter organic materials that float to the surface Signup and view all the answers

What is a wet vent?

A vent pipe through which wastewater also flows. Signup and view all the answers

What distinguishes a looped vent?

It connects at a point downstream of the last fixture connection. Signup and view all the answers

In what situation is a utility vent especially useful?

In underground public restrooms where space is limited. Signup and view all the answers

What is the minimum diameter for an individual vent pipe connected to a drain?

32 mm (1-1/4 inch). Signup and view all the answers

Which condition must be met regarding horizontal or branch vents?

They should be graded to drip back by gravity to the drainage pipe. Signup and view all the answers

What is the required vertical rise for vent pipes above the highest-level rim of fixtures?

152 mm. Signup and view all the answers

What should be the minimum distance of a vent opening from any openable window?

0.90 m. Signup and view all the answers

How far should vertical vent pipes extend from any part of a roof used for human activities?

2.10 m. Signup and view all the answers

Study Notes

Week 4-6 Unit Learning Outcomes (ULO)

Sewage disposal system knowledge of parts and functions is expected.
Storm drainage system knowledge of parts and functions is expected.
Plumbing fixtures, appurtenances, appliances, and accessories must be distinguished.
Plumbing materials, tools, and fittings must be recognized.

Sewage Disposal System

A system for collecting, transporting, treating, and disposing of sewage.
Sewage includes liquid waste with animal or vegetable matter in suspension or solution; may also include chemicals in solution.
Sewers are pipes or conduits for carrying sewage and wastewater.
Public sanitary sewers allow all abutters to connect.
Public toilets are facilities in public markets, bus stations, buildings, etc.

Drainage Systems

Piping within a public or private premise that carries sewage, rainwater, and other liquid wastes to a disposal point.
Drainage systems don't include public or private sewage treatment or disposal plants' mains.

Individual and Communal Excreta Disposal Systems

Individual system serves a dwelling unit.
Communal system serves a group of dwelling units.

Leaching Tile Systems

Distribution lines from the distribution box to the drain field.
Distribution boxes are concrete receptacles between a septic tank and the drain field.
Domestic sewage consists of human excrement and liquid household wastes.

Sanitary Drainage and Vent Piping Systems

Plumbing fixtures and appliances are connected by the plumber to remove waste.
Plumbing circulation of air within the drainage piping is provided by these systems.
Stack is the general term for vertical lines of soil, waste, or vent piping.

Soil and Waste Pipes

Soil pipes carry waste from water closets, urinals, etc.
Waste pipes carry liquid waste without fecal matter.
Soil and waste stacks are pipes that convey waste from associated fixtures.

Building Drain/House Drain

Horizontal plumbing within a building to convey waste to the building sewer.

Building Sewer/House Sewer

Part of a drainage system, conveying waste from building drains to the public sewer, private sewer, or individual sewage disposal system.

Drain

Pipe that carries water and waste in a building drainage system.

Air Break

Physical separation between a waste pipe and an indirect waste receptor or device.

Backflow

Reverse water or wastewater flow in pipes.

Back Pressure

Pressure greater than atmospheric pressure within a sanitary drainage system.

Back Siphonage

Contaminated water flowing from a fixture into a potable water system via negative pressure.

Branch Interval

Vertical length of a soil or waste pipe stack, typically 8 feet.

Indirect Waste Pipe

Waste pipe that discharges into a plumbing fixture or receptacle.

Insanitary

Conditions contrary to sanitary principles or that are dangerous to health.

Main

Principal pipe that branches are connected to.

Privy

Outhouse or structure used for waste disposal.

Public Sewer

Sewer that allows all abutting property owners to connect. Controlled by public authority.

Septic Tank

Watertight receptacle where sewage is digested.

Sludge

Solid organic matter at the bottom of a septic tank.

Scum

Lighter organic matter that settles on top of water (septic tank).

Effluent

Liquid content of sewage.

Manhole

Opening large enough for access to a plumbing system.

Siphonage

Suction created by flow in pipes; lower than the atmospheric pressure.

Sump

Tank pit receiving waste from lower levels; mechanically pumped.

Ventilation

Process of supplying and removing air from a space, by natural or artificial means.

Vent

Pipe that permits air circulation in a plumbing system and prevents traps from siphoning.

Vent System

System of pipes and openings for air circulation, in a plumbing system.

Vent Pipe

Part of the system that leads outside air to a drainage pipe near traps; connected.

Vent Stack/Main Vent

Vertical vent pipe for providing air circulation to the building's drainage system.

Stack Vent/Soil and Waste Vent

Extension of a soil or waste stack above the highest branch drain/fixture.

Individual or Back Vent

Vent system that connects to a single fixture.

Unit/Common/Dual/Duplex Vent

Vent pipe connected to a double fixture trap.

Circuit Vent/Branch Vent

Vent arrangement for a group of fixtures; connects to a vent stack.

Looped Vent

Vent system for fixtures in a room away from a wall.

Yoke Vent

Vent pipe connecting an upward soil or waste stack to a vent stack.

Wet Vent

Vent pipe that doubles as a fixture branch (waste).

Fixture Vent

Vent pipe that connects a drainage pipe to another vent or to the atmosphere.

Branch Vent

Vent connecting individual vents to a vent stack.

Local Vent/Local Ventilating Pipe/Vapor Vent

Pipe used to draw vapor or foul air from a room.

Ejector Vent

Pipe that prevents pressure buildup in a sump pit.

Trap

Fitting that creates a liquid seal to prevent sewer gas emission.

Trap Seal

Vertical distance between trap dip and crown weir; water.

Dip

Lowest portion of a trap's inside channel.

Crown Weir

Highest point of a trap's bottom channel.

Sanitary Drainage System Subsystems

Waste collection and ventilation systems.

General Rules in Designing the Sanitary System

Pipes should take the shortest possible route to sewage systems or termination points.
Control components, like clean-outs, traps, and vents, should be placed strategically for efficient flow.
Horizontal piping should be supported and anchored in intervals no more than 3 meters.
Vertical piping needs secure support and alignment.
Each fixture trap needs a vent pipe.
Cleanouts are required for piping inspection.
Minimum sloped piping (2%) for sanitary drainage lines is needed; exceptions apply.

Septic Tanks

Watertight receptacles to receive sewage and retain solids; process organic matter.
Sludge accumulates at the bottom, and scum floats.
Digestion occurs via anaerobic bacteria.

Septic Tank Sizing

Smaller tanks are not practical due to needing room for accumulated sludge.
Larger tanks are inefficient (slow down bacterial activity).
Codes/standards provide standard tank sizes for a given number of persons served.

Sewage Treatment Plant (STP)

Aeration system in STP.
Sludge disposal via water pump.
Clarification/separation occurs.
Usually includes blowers and electronic controls.

Sewage Piping Sizes

Pipe sizes depend on waste amounts.
Fixture Units (FU) rate plumbing fixtures based on trap size requirements.
Discharge capacities are calculated.

Trap Requirements

Each fixture needs a separate, approved trap with a water seal.
No more than one trap per trap arm.
One trap can serve 3 fixtures within .75 meters of each other.

Trap Classifications

Permissible traps include P-traps, S-traps, and goosenecks.
Drum traps are designed for bathtubs (contain a large water volume).

Running Trap/House Trap

Prevents air circulation between building drains and building sewers.

Grease Trap/Interceptor

Designed for separating and retaining grease from 1 to 4 fixtures; must have 3m³ capacity.

Mechanical Sealed Traps

Grease traps that are remotely located.

Internal Partition Traps/Light Metal Traps

Traps based on a metal partition.

Trap Sizes

Trap sizes match the size of the trap arm.
Minimum trap sizes for common plumbing fixtures are listed.
Vertical and horizontal trap distances are specified (not to exceed 0.6 meters or 1.8 meters).

Cleanout Requirements

Cleanouts must be accessible in horizontal sewer or drainage lines.
Must be spaced 15 meters apart (every 50 ft).
Offset angles exceed 135° need more cleanouts.

Cleanout Sizes

Cleanout size equals the pipe served.
Sizes are standardized for plumbing codes.
Cleanout installation is in the flow direction or at a right angle (except for wye branches).

Vent Requirements

Each trap needs a separate, approved vent.
Each plumbing branch needs a vent.

Vent Classification

Main soil/waste vent (acts as a backbone for the sanitary system).
Main vent (acts as a collecting line for branches).
Individual vent/back vent.
Unit vent/Common vent/Dual vent (serves multiple traps).
Circuit or loop vent (serves several fixtures).
Relief Vent (provides air circulation between drainage and vent systems).
Yoke vent (A type of Vent that serves as an auxiliary vent, especially for large buildings where it's used for connection between the soil and vent stacks).
Wet Vent (A vent pipe through which wastewater flows)..
Looped Vent (A vertical vent connection to a horizontal vent.)

Local Vent

A pipe that conveys foul air from a fixture or a space to the outer air.

Utility Vent

Used for basement or underground public restrooms, where vent stacks are not possible.
The sizes are determined based on the total fixture units.
The diameter of an individual vent must be at least half the size of the drain.

Vent Stack and Relief Vents

Soil or waste stack extending ten (10) or more stories above a building drain must be supported by multiple vents.

Trapseal Loss

Direct effect of Minus and Plus pressure.
Siphonage - direct and momentum.
Evaporarion
Wind Effects
Retardations of Flow (gravity, atmospheric pressure)
Deterioration of Materials.

Sample Illustrations/Layouts of Sanitary Systems

DWV system includes traps and wastes lines.
Illustrations of the system's components (vent, waste, and soil stacks) are provided
Diagrams of the system's layout, using different pipe types and fixtures, are included.
Additional illustrations will be available via the LMS.

Question and Answer

Questions about the topics are welcome; use the BlackBoard LMS forum.

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Description

Test your knowledge on the regulations and requirements for septic tanks and sanitary sewers. This quiz covers essential topics such as minimum height standards, materials used, and sizing for sewer systems. Perfect for environmental studies and civil engineering students.