S-B Flashcards
What type of fire extinguisher do you use with an electrical fire?
Halon (Rated for Class C fire)
According to MN department of labor and industry, how many people should be at the outside entrance of a confined space when occupied?
One, with radio contact
What should the alarm set point be for an H2S meter?
10 ppm
1 ppm recommended
What three things should be on the tag attached to something that has been locked out?
Signature or initials of who locked it out
Date
Project
A material safety data sheet (SDS sheet) contains information on what three things?
Flammability limits
PPE
Hazards
What is the minimum percent oxygen in an atmosphere that is deemed safe by OSHA and MnOSHA?
19.5%
Alarm settings on explosive meters should be adjusted to go off when the concentration reaches ________ of the LEL.
10%
What is one item that is one of the most important pieces of standard safety equipment for field crews?
Atmospheric testing equipment (gas meters)
What is one safety program responsibility of the field supervisor?
Identify and correct unsafe practices and conditions
What is an important factor when considering what type of trench shoring to use in an excavation?
Soil structure
What is the first thing that you should do prior to beginning an excavation in order to determine the location of buried utilities?
Call GSOC (Gopher State One Call)
What does MSDS stand for (now SDS)?
Material Safety Data Sheet (Safety Data Sheet)
What does OSHA stand for?
Occupational Safety and Health Association
OSHA makes rules that govern workplace what?
Safety
States can adopt OSHA workplace safety rules or make them more stringent, but not what?
Less stringent
Odorless, colorless, lighter than air, and explosive are traits of what gas?
Methane
If I and I is reduced, and flow is reduced, H2S in the sewer could what?
Increase
When flagging for traffic control, may the flagger override stop or yield signs?
Yes
Methane has a specific gravity of 0.5537. Is this lighter or heavier than air?
Lighter (air is 1.0)
Since methane is lighter than air, where would it be in a manhole?
Top of manhole
Hydrogen sulfide (H2S) has a specific gravity of 1.1763. Is this lighter or heavier than air?
Heavier (Air is 1.0)
Since hydrogen sulfide (H2S) is heavier than air, where would it be in the manhole?
At the bottom
Who take precedence, OSHA or MnOSHA?
OSHA
What covers all physical and safety aspects of a substance, including boiling point, specific gravity, flammability, explosion, LEL limits and suggested PPE?
SDS of a substance (Safety Data Sheet) formerly MSDS
How long do you retain a SDS (Safety Data Sheet)?
Keep forever
What is one method of reducing infiltration?
Sliplining (or other types of lining)
What type of piping material should be used for a shallow line under a busy highway?
Ductile iron (DIP)
What develops when the flow velocity in a collection system is two feet per second or more?
Scouring action
Daily activity reports are used for ___________ or _____________ personnel to work crews.
Rotation, reassigning
What is the minimum allowable diameter of a manhole?
48 inches
You have a 60 inch interceptor sewer and waste is flowing at 15% of the design flow through it, this may allow the waste to turn ___________ prior to reaching the WWTP.
Septic
Manholes must be installed how far apart for a 12 inch sewer line?
400 ft apart
When using a floating object in a sewer half full to measure flow velocity between manholes, the velocity of the float will be what?
Average velocity of wastewater
What is the minimum horizontal distance between water mains, and sewer lines?
10 ft
Why should trenches be properly backfilled and compacted?
To prevent damaging pipes from settling
What is the maximum size (rating) of fuse placed in the electrical circuit of a motor having a low starting load?
3 X the motor (whatever is on the data plate)
When shoring a trench, the uprights must be within ________ ft from the bottom of the trench.
1.5 ft
Collection systems are designed to convey peak flows for a period of how many years?
10-30 years (20 years)
If a lift station discharge pipe has lots of valves and fittings what should be taken into consideration when designing the pipe?
Friction loss
What is the minimum vertical distance between water and sewer lines?
18 inches (1.5 feet)
What is required when a sewer line enters a manhole 24 inches or more above an invert?
Drop line (Drop)
An area that is not designed for continuous operator occupancy is considered a what?
Confined space
Advance warning, transition, buffer, work, and termination are the 5 things in order, necessary for a proper what?
Traffic control zone
What are the three different mandatory protective systems for operators working in excavations or trenches?
Shoring, shielding, sloping/benching
What gas commonly found around decaying organic matter is highly toxic, smells like rotten eggs, and is heavier than air?
Hydrogen sulfide
What does LEL stand for?
Lower Explosive Limit
When working in a confined space, an operator must always wear what?
Safety harness with lifeline
When there will be operations performed in a confined space that may produce a spark, what is required?
Hot Work Permit
What is the IDLH (Immediate Danger to Life and Health) level for hydrogen sulfide?
0.15% or 1500 ppm
The procedure to calibrate a gas meter with gas canisters is called a what?
Bump test
At what excavation depth does OSHA require shoring?
5 feet
What is the most typical type of pump used in lift stations?
Centrifugal
If a pump sounds like it’s pumping rocks or marbles then the pump is most likely what?
Cavitating
The line that goes from a private residence or commercial establishment to the main sewer is what?
Sewer lateral
What is the minimum velocity that sewage should flow in a collection system?
2 feet per second
The main line coming out of a lift station is considered a what?
Force main
High velocity (jet) cleaning and poly pigs are considered what type of sewer cleaning methods?
Hydraulic sewer cleaning
The lowest area of a manhole would be considered what?
The invert
The typical method of disposal of screenings from a lift strip would be to get them _____________ and ____________ in a landfill.
Dewatered, buried
If you notice septic or floating sludge in a lift station wet well, although pump meters all read normal, you would need to ____________ the frequency of pumping.
Increase
If a three phase motor has lost one phase, what will happen when the operator turns it on?
It will not start
What is a method of placing a new service line under a major thoroughfare without disrupting traffic?
Directional boring
Why should lift station pumps not be allowed to start and stop frequently?
It will cause excessive wear on the motors
When a manhole frame and cover is 6 inches below grade what is typically installed to raise it to proper grade?
Grade rings
The decay of organic matter when there is little or no oxygen present is called what?
Anaerobic decomposition
The vertical scale on a pump curve indicates what?
Total dynamic head
The connection between a storm sewer and a sanitary sewer would be considered a what?
Cross connection
If a lift station overflows and causes a spill on a weekend, when should the operator notify a state duty officer?
Within 24 hours of spill
What prevents a backsiphonage of sewage into potable water?
Air gap
