Wastewater Collections Class D Test Questions

What are the safe oxygen levels?

19.5-23.5

How far away from an excavation must dirt be kept back?

2'

What water velocity speed is required for the wastewater collection system to perform as designed?

2' per second

Ladders in excavations aeas should stick out above the ground how many inches?

36"

HVC's are best suited to optimally clean what diameter piping?

4-20 inches,

What is the correct way to connect a tap to a main line?

90 degrees parallel to the main line.

What is a safety precaution required for visiting a pump station?

Always 2 persons are required

What is one way to think about the operation and maintenance of a wastewater collection system?

As protecting the capital investment the community has made in the wastewater collection system.

What can be located using smoke testing?

Broken sewers due to settling of foundations, manholes, and other structures.

What types of sewer line problems can be located by using the mandrel test?

Building sewer connections that protrude into the main lines.

Who hires collections system operators?

City, county, a special purpose district or a sanitation district, or a private utility company.

When basements flood what should be shut off?

Electrical and gas utilities

How often should you an existing manhole be inspected?

Every 1-5 years

Methane is what type of gas?

Explosive and Flammable

What does F.O.G. stand for?

Fats, Oils, and Grease

The floor of a wet well is?

Flat and level

What are used to estimate volocities in existing sewers?

Floats

The pig is utilized in what type of Piping?

Force mains

What does the locate color yellow mean?

Gas line

What is the symbol for Hydrogen Sulfide?

H2S

Wastewater personnel should be vaccinated against what types of diseases?

Hepatitis A, B and Tetanus

Why is it dangerous to drive over a rocking or improperly seated manhole lid?

It can flip over and cause an accident or damage to a vehicle

What should be done before working on any equipment that could start up or release stored energy?

Lock out tag out procedures

When conducting work on a pump, what is the most important thing to do FIRST?

Lock out/Tag out procedures

What condition may not produce a scouring or self-cleaning velocity in a sewer?

Minimum daily flow

Who is overall responsible for grease traps?

Municipality

How many times can lead gaskets be reused on chloride tanks?

Never

What should be conducted prior to any smoke testing?

Notification of the public and other agencies

What is important to do prior to conducting smoke testing of an area?

Notify residents of the testing

What does a voltmeter test for?

Ohms, watts, voltage

Which O&M programs are similar to those of wastewater collection systems?

Other utilities

How is pipe thickness measured?

Outside diameter

An atmosphere that is 18.5% oxygen is what?

Oxygen deficient

What type of pipe is flexible?

PVC

What is used to clean a force main?

Pig

What information is used to calculate the flow rate of a sewer?

Pipe cross-sectional flow area

When should notification of the downstream wastewater treatment plant be conducted?

Prior to clearing a large septic stoppage.

What type of pipe joints are available for nearly all types of pipe used in collection systems today?

Push-on

What type of respirators are suitable for confined space entry in a low oxygen environment?

Self-contained breathing apparatus (SCBA) and Supplied-air respirator (SAR)

What problems can be caused by solids settling out of wastewater in sewers?

Sewer stoppages and generation of hydrogen sulfide gas

Where is the invert located?

The bottom of a manhole

What is a barrel in relation to piping?

The cylindrical part of a pipe that may have a bell on one end

On the bubbler for a pump station, which end is open?

The one in the wet well.

What is one way plumbers can create obstructions in systems?

The placement of building sewer taps protruding into the main sewer.

What is infiltration?

The seepage of groundwater in a wastewater collection system through defective or cracked pipes, joints, and connections.

You have a pump that is leaking, what should be checked first?

Tighten the packing gland.

What is the purpose of interconnector sewers?

To allow the regulation of wastewater flows in parallel sewers or the automatic diversion of wastewater to an alternate sewer if the primary sewer becomes blocked.

When would you use disinfectant in a sewer system?

To decontaminate a work area

What is the primary function of TTC's?

To provide for the safe and effective movement of vehicles and pedestrians through or around TTC zones.

Hydrogen Sulfate is what type of gas?

Toxic

Who should be notified when conducting upstream inspection activities?

Treatment plant operators and industrial waste inspectors.

What directions should the cleaning nozzle of a high-velocity cleaner be pointed during cleaning?

Upstream of the operating manhole

What does the term inflow refer to?

Water discharge into a collection system from an outside source

What are the LEL limits for explosive gasses?

When it exceeds 10 LEL

What does the term Lond-Term Stationary mean?

Work that occupies a location for more than 3 days.