Practice Exam 8

what is the MCL for haloacetic acids (HAA5)?

0.060mg/L

in lime softening facilities it is normally a good practice to store a minimum of __ supply of each chemical

1 months

sites requires to do a site assessment under the process safety management (PSM) regulations (OSHA) id the facility in a single process has more than how many pounds of chlorine

1,500lb

what is the action level for copper?

1.3mg/L

in general compliance testing results must be reported no later than __ after the end of the month in which they were accumulated

10 days

depending on water temperature what is the typical backwashing flow rate for manganese greensand filter bed?

10-12 gpm/ft2

normal air to water ratio at peak flow in a packed tower aerator

25:1

the American water association recommends that the water treatment chemicals be purchased in quantites that maintain a minimum supply at all times of

30 days

the head of a double suction pump can reach

350 ft (100m)

peoples teeth are liked to become pitted when the fluoride concentration in drinking water goes about what amount?

4 mg/l

when backwashing an ion exchange unit how much should the bed expand from water introduced from the bottom of the ion exchange column

50-75%

weak base anion exchange resins behave much like their weak acid counterparts they do not remove anions about a pH of

6

the operator must periodically check to ensure that at least ___ of chemical is maintained in the saturator at all times?

6 in (150 mm)

what is the optimal pH range for the removal of particulate matter when using alum as a coagulant?

6.5 to 7.2

bored wells constructed with an auger driven into the earth are limited in depth to approximately

60 ft

samples to be tested for coliforms can be refrigerated for up to ____ hours before analysis but should be done as soon as possible?

8

when using four packing rings the rings should be staggered at

90 degrees

when a water sample is acidified the final pH of the water must be?

<2.0

which of the following composes the majority of scale in pipe

CaCo

the corrosion process can be accelerated by certain bacterial organisms because they produce which chemical

Co2

which chemical is used to remove residual chlorine from water?

Na2S2O3

which organization issued the risk managements rule on July 20, 1996 in an effort to protect public health and safety

USEPA

how is velocity head expressed mathmatically

V2/2g

gravel displacement in a filter bed from back wash rates with too high of velocity could eventually cause?

a sand boil

as solids settle to the bottom of a sedimentation basin?

a sludge layer develops

the length of filter runs for manganese greensand filters can be increased by?

adding a layer of anthracite above the greensand

where should the fluoride injection point be located?

after water has received complete treatment

dissolved air-flotation is particularly good for removing?

algae

common mistake that operators make in regard to flocculation units?

allowing excessive flocculation time

in water treatment operations corrosion can occur to some extent with?

almost all metal that is exposed to water

where are the sampling point(s) located for the required sampling of turbidity in a community water system?

at point(s) where water enters the distribution system, including all filter effluents is a surface water treatment plant

tin in a typical air scour sequence air is applied ___- back wash water is introduced

before

what is not a component of a Bourdon tube pressure gauge

bellows

the example of _____ is determining the lowest monthly average during 12 month monitoring of Giardia and virus inactivation.

benchmarking

particle counters use the principal of light?

blockage

to reduce noncarbonate hardness soda ash must be added to water to form

calcium carbonate

GAC contractors can be used when formation of trihalomethanes and other disinfection by products __ and adjustment of the disinfectants or other treatment processes

can not be prevented by

which type od aerator causes aeration to occur in splash areas and can be used to oxidize iron and partially reduce dissolved gases

cascade aerator

Under the surface water treatment rule, disinfection residuals must be collected at the same location in the distribution system as?

coliform samples

C x T values are based on?

concentration of chlorine contact time pH and temperature

an artesian aquifer could occur in a(n)

confined aquifer

stabilization refers to the treatment process used to control?

corrosion

which device(s) uniformly disperse(s) the chlorine solution into the main flow of water?

diffusers

which type of aerator is much more efficient in removing dissolved gases and for oxidizing iron and manganese

draft aerator

if the natural fluoride content of the raw water is variable the concentration of the raw water should be measured?

every day

how often should the fluoride concentration of treated water be measured?

everyday

once the ion exchange resin can no longer remove hardness it is said to be?

exhausted

what is the rationale for establishing the three categories of public water systems?

exposure differences to contaminants

which type of continuous control requires meters transmitters and transducers

feedback control

which type of continuous control will maintain control action when signal is lost

floating proportional control

if run tomes between bachwash are long (1 week) because of high quality (low turbidity) water is being applied to the filters, which problem could still rise?

floc breakthrough

water that contains high concentrations of __ can cause the consumption of lime when using this method of softening

free carbon dioxide

which material is manganese greensand and which is the coating

glauconite sand coated with manganese dioxide

which type of sample should always be collected for determining the presence of coliform bacteria?

grab sample

many streams would dry up after a rain if it were not for

groundwater flow

the advantage of using the oxidant ozone is that it?

has little pH effect

chlorine storage room should?

have a window in the door so an operator can look into the room to detect abnormal conditions

chlorine cylinders must be stored

in a temperature controlled room

ion exchange process can typically be used for direct groundwater treatment as long as turbidity and ___ levels are not excessive

iron

how should burning carbon be handled

it should be covered with a fine mist of spray from a hose or a chemical foam extinguisher

block salt is sometimes used for home softners but is not suitable for larger installations because

its small surface area does bnot allow it to dissolve fast enough

which determines the calcium carbonate deposition property of water by calculating the saturation pH where negative value indicates corrosive water and a positive value indicates depositing water?

langelier saturation index

which index determines the calcium carbonate deposition property of water by calculating the saturation pH where a negative value indicates corrosive water and a positive value indicates depositing water?

langelier saturation index

conventional sedimentation has an ___ removal of cryptosporidium oocysts.

less than 0.5-log

the minerals that cause noncarbonate magnesium hardness are precipitated out of water by the addition of?

lime

which flow measuring device is mechanical

loss of head meter

sequestration is effective only for groundwater with a relatively?

low level of dissolved iron and manganese and no dissolved oxygen

which type od aerator consists of a propeller like mixing blade mounted on the end of a vertical shaft driven by a motor

mechanical aerator

jar test results are expressed in?

milligrams per liter

Ferric sulfate has which advantage over aluminum sulfate (alum)?

more dense floc

because harmful bacteria do not penetrate very far into the soil wells are generally free of harmful organisms if

more than 50 ft (15m) deep

powdered activated carbon is primarily used to control

organic compounds responsible for tastes and odors

in controlling corrosion what should be continuously monitored and recorded as water enters the distribution system

pH of water

which device applies an even pressure to the packing such that it compresses tight around the pump shaft

packing gland

what is the term for a conical tank in which the softening reactions take place quite rapidly as the water swirls upward through the unit

pellet reactor

which chemical would be best to use for corrosion inhibition of the water is very low in alkalinity and calcium concentration

polyphosphates

what is the major cause of short-circuiting in a sedimentation basin?

poor inlet baffling

___ is used as an oxidant for iron and manganese control, some organic precursor control and taste and odor control

potassium permanganate

manganese greensand filters can be generated by using?

potassium permanganate solution during backwash

which type of continuous control has a controller that constantly tries to change the output if there is deviation from the set point

proportional plus reset control

which type of well is commonly used near the shore of the lake or neat a river to obtain a large amount of relatively good quality water from adjacent sand or gravel bed

radial well

which type of wells are commonly used neat the shore of a lake or near a river

radial wells

filter tanks are generally?

rectangular and constructed of concrete

best type of salt to use in regeneration of ion exchange softener resin?

rock salt or pellet type salt

immediately below the water table is the

saturated zone

layer of solids and biological growth that forms on the top of the slow sand filter?

schmutzdecke

which conventional treatment step is eliminated by direct filtration?

sedimentation

which type od centrifugal pump impeller is used for pumping medium sized solids

semi open

which of the following is not a method by which aquifer performance can be evaluated

sequestration

immediately occur if newly installed manganese greensand was not skimmed of the fines after backwashing and stratification steps were completed?

shorter filter runs

only a human operator can determine certain elements of plant operation such as those involving

sight sound or smell

pretreatment with chlorine is being eliminated at many water treatment plants because it has been shown to?

sometimes produce disinfection by products known to be carcinogenic

in a slate and coke tray aerator the aerator is usually constructed to having sloping sided called __ which are used to protect the splash from wind loss and freezing

splash aprons

what term refers to the level of the water surface in the well when no water being take from the aquifer

static water level

____ aerators draw water into the blade of the aerator and throw the water into the air in tiny droplets so that the water can pick up oxygen

surface

the pressure in a chlorine cylinder depends on the?

temperature of the chlorine liquid

if a substantial chlorine leak incident occurs which agency should be called for actual hands on assistance

the chemical transportation emergency center

before an authorized entrant enters a permitted confined space?

the internal atmosphere of the space must be tested to measure oxygen content presence of flammable gases and vapors and potentially toxic air contaminants

what happens at the surfaces of the PAC particles if they are coated with coagulants or other water treatment chemicals

they lose their capacity to absorb

the shafts main function is to transmit __ from the motor to the impeller

torque

the lower the ____ the more difficult it is to from proper floc.

turbidity

the partnership of safe water suggests that the __ (the particle count if available) in each sedimination basin be recorded periodically

turbidity performance

if enteric disease- causing protozoans have been found in the effluent of a water plant, what is the most probable solution?

use the multibarrier approach-coagulation, flocculation, sedimentation, ad filtration

which type of chlorine gas feeder is most commonly used?

vacuum

which forces will pull particles together once they have been destabilized in the coagulation flocculation process?

van der waals forces

distribution system samples are intended to measure the quality of the water at?

various pints in the system

a major consideration in starting and stopping large pumps is the prevention of excess surges and __ in the distribution system

water hammer

at the surface all wells should have a sanitary seal which prevents contamination from entering the

well casing

chlorine gas?

will support combustion