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125 Cards in this Set
- Front
- Back
The bottom and inside of a pipe
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invert
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Length of pipe connecting two manholes
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pipe run
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In a sewer line to carry uninterrupted flow under a stream/river
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inverted siphon
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Smoke and dye testing can determine sources of
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inflow and infiltration
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A manhole with an inlet pipe above the invert, allowing flow to drop down into the manhole
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drop manhole
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one way to control root-intrusion in a collection system
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proper construction of joints and fittings
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lots of rags getting into a treatment plant can
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plug pumps and fill digesters
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too many organics are collection in the grit channel, what is one solution
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increase the velocity
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flow volume through a grit channel should be about
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1 cubic foot per second
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corrosion in manholes is caused by
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hydrogen sulfide gas
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when digging for a sewer line, dig about ____ above where it is shown on plans
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18 inches
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operators _____ lagoon levels in fall and ____ lagoon levels in spring
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raise in fall
lower in spring |
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the level is dissolved oxygen is greatest at ___
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mid-afternoon
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if a stabilization pond is going septic ____
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raise the level
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Records of discharge monitoring reports (DMRs) must be kept _____
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for three years
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The working area remaining above the waters surface in a lagoon
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free board
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Chlorine is _____ than air
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heavier
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in an intermittent sand filter, the top ______ inches of sand is replaced during normal operation
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1-3 inches
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the greatest maintenance task for intermittent sand filters
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cleaning of the sand
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The min. acceptable limit for oxygen in a confined space
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19.5%
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fecal coliform tests measure
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pathogens
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what is used in the lab for dechlorination
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sodium thiosulfate
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total suspended solids are measured by
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filtering through a gooch crucible
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what two diseases are associated with wastewater
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hepatitis and dysentary
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what can be added to help restore aerobic activities to a faculatative lagoon that has turned anaerobic
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sodium nitrate
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Lagoons operate the best with ____ temperatures
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warm temperatures
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what is a reason to operate 3 cell faculatative lagoon in series mode
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low organic loadings in summer
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to calculate flow through a parshall flume, what is measured
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hydraulic head
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overheating an electric motor does what
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shortens the insulation life of the windings
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if a three phase motor is running backwards, what corrects the problem
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reverse the two motor leads
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a grounded three phase motor loses a phase will do what?
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heat up and sustain damage unless shutdown by a thermal controlling device
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what causes a motor to have a chattering or noisy magnet
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low voltage
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what is used in pumps to prevent water from getting out and air from getting in
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packing
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what kind of pump can be started with a closed discharged valve causing no damage
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centrifugal pump
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a piston pump has how many check valves
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2
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the velocity of a collection system is designed for
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2 feet per second
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the best way to determine if a chlorine tank is empty
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weighing them
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if one circuit burns out in a series circuit, what will happen
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all circuits will go out
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what color indicates the pond is running correctly
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a green color
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how deep should a pond be for weed control
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a min. of three feet
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that chemical is used to increase d.o. in a lagoon
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sodium nitrate
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what is daily use of chlorine referred to as
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chlorine demand
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what material is not normally used in construction of a collection system
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iron
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performance of a stabilization pond is a function of.
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surface area
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The destruction of all microorganisms
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sterilization
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what temperature does a fusible plug melt at
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158-168 degrees
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Dissolved solids make up of _____ % of total solids
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40%
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Suspended solids make up ____ % of total solids
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60%
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Type of pond used in a series after a trickling filter plant
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polishing pond
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during the ______ algae used CO2 and its pH is
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Day, Raised
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how long does it take to get a thriving population of bacteria in a pond
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60 days
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What should the pH of a pond be
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above 7.5
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BOD, fecal coliform, solid tests measure ______ on a pond
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loading
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pH, dissolved oxygen, temperature are indicators of _____ in a pond
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condition
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test samples in a pond should be taken _____ feet out from the waters edge, and ____ below the surface
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8 feet and 1 foot
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pH and DO will be the _____ just at sunrise
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lowest
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how wide should the top of the levee be
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10 feet
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Combined chlorine
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chloramines
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Purpose of adding sodium thiosulfate to microbiological lab tests is to
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remove any chlorine residual present
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What causes the greatest friction loss in a pipe
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increasing the velocity of the wastewater
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the ash content is the same as
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inorganic solids
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how can you tell if a new pump is delivering design flows and pressures
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review several months of records and look for sudden variations
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pump packing should be
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tightened down to a drip
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a piston or diaphragm pump would be used for pumping
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primary sludge
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the most critical criterion for determining when a mixed media filter should be backwashed
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filter effluent quality
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what problems can develop if too much grease is used in lubricating an electric motor
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may cause bearing problems or damage to windings
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the COD test
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provides quicker results than a BOD test
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a chlorine demand test will show
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amount of chlorine required to give the desired residual after a given time
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the most important rule in flow meter maintenance
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the instruments should be kept clean and in good working conditions
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the chemicals are added to distilled water for the BOD test serves what purpose
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adjust the pH within a desirable range and provide essential elements for the growth of biological life
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most abundant pollutant entering natural bodies of water
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non-point source
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how many people are required to enter a manhole
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3
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what information should be on a warning tag attached to a switch that has been locked out
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signature of person who locked out switch
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how should a fecal coliform sample be taken
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a grab sample preserved with sodium thiosulfate
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what are the top three injuries in wastewater
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back, leg, hand
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what allows water to pass in 1 direction
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check valve
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highest concentration of algae growth in facultative pond is located
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near the top
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what is the purpose of air gap device
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prevent contamination of potable water system
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what does a slow drip indicate on a centrifugal pump's rope packing
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packing bolts/nuts on packing gland is not properly adjusted
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how are motors rated
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horse power and duty cycle
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how deep are facultative lagoons
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3-6 feet deep
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how deep are aerobic lagoons
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3-4 feet deep
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what does the term septic mean
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little or no dissolved oxygen
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what lab test are no chemicals used
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suspended solids
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total solids are made up of
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suspended + dissolved solids
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fresh wastewater appears as what color
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gray
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what is heavy course mixture of grit and organic materials
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detritus
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what color does chlorine gas appear
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greenish-yellow
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sand drying beds should have a maximum application depth of
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8-12 inches
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sand depth in intermittent sand filters is how many inches
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24 inches min.
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what happens if you run a constant flow over sand filters
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could clog and plug up filters
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what is used to determine amount of settleable solids
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imhoff cone
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what is always used to pipette waterwater or chemicals
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a rubber bulb
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disease causing bacteria is referred to as
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pathegenic
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type of bacteria indicates poor conditions in a pond
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blue green algae
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what type of pump can be started with a closed discharge valve causing no damage
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centrifugal pump
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surface loading on facultative ponds
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15-30 lbs bod/acre/day
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surface loading on tertiary ponds
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5-15 lbs bod/acre/day
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surface loading on anaerobic ponds
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200-1,000 lbs bod/acre/day
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surface loading for aerobic ponds
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60-200 lbs/bod/acre/day
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When are ponds used in parallel form?
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to reduce organic loading in primary cells
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When are ponds used in series form?
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if loading is below design
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Type of pond that receives raw untreated waste
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stabilization pond
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type of pond that receives treated waste and serves as secondary treatment
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oxidation pond
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what color in a pond indicates a pond with a high (alkaline) pH
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Green
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What color in a pond indicates a low (acidic) pH
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Yellowish-green
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When will pH be its highest in a pond
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late afternoon
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When will pH be its lowest in a pond
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early morning
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Where would you find information on when to lubricate a pump?
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should be in accordance to manufacturers recommendations
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why should a pump with a mechanical seal never run dry
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water is required for seal lubrication
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what factor influences the rate of brush wear in pumps
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brush pressure
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what should you check if a pump will not start
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check for blown fuses or tripped circuit breakers
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what should you check if flow rate from a pump is lower than expected
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check for something causing the reduced rate of discharge like pumping air, motor malfunction, or plugged lines
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what should be done before stopping an operating pump
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start another pump (if needed) inspect the operating pump for developing problems, required adjustments and problem conditions
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what happens when a pump shaft or motor to spin backwards
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if wastewater being pumped flows back through the pump when the pump is shut off
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What are possible causes of a pump motor or shaft to spin backwards
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a possible faulty check valve or foot valve
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what is the most important rule in operating a positive replacement pump
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never start the pump against a closed discharge valve
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what could happen if a positive displacement pump is started against a closed discharged valve
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the pipe valve or pump could rupture from excessive pressure
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how can you tell if a new pump is delivering correct design flows and pressure
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measure the flows and pressures and compare to pump performance provided by supplier
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is a slight water seal leakage desirable for a pump with packing gland when it is running
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yes, because it keeps the packing cool and in good condition
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what are two things that should be done to a pump if it is shut down for extended periods of time
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pump should be drained to prevent damage due to corrosion and the motor disconnected
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what are three common reasons shear pins fail
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solid objects lodged under the piston
clogged discharge line stuck or wedged valve |
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why should inactive gate valves be opened periodically
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to prevent sticking
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what are two things that need to be done to maintain a portable gas detector
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make sure battery is charged and calibrate using known standard gas concentrations
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what is the basic flow formula
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flow = cross sectional area * velocity
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