CWS 102

Question 1

How many gallons are in one cubic foot?

Answer 1

7.48 gallons

Question 2

1 MGD is equal to how many cubic feet per second?

Answer 2

1.55 cfs

Question 3

1 MG is equal to how many acre feet?

Answer 3

3.07 af

Question 4

How much does a gallon of water weigh?

Answer 4

8.34 lbs

Question 5

How many square feet are in 1 acre?

Answer 5

43,560 square feet.

Question 6

1 cubic foot per second is equal to how many gallons per minute?

Answer 6

448.8 gpm

Question 7

How many cubic feet are in one acre foot?

Answer 7

43,560 cubic feet

Question 8

What do you multiply MGD by to get cfs?

Answer 8

1.55

Question 9

How many gallons are in 1 acre foot?

Answer 9

325,851 gallons

Question 10

How many minutes are there in 1 day?

Answer 10

1440 minutes

Question 11

How many seconds are there in 1 day?

Answer 11

86,400 seconds

Question 12

How is tank Rise and Fall calculated?

Answer 12

Tank rise (or fall) = Gallons (into or out of tank) / gallons per foot

Question 13

How is Volume Change calculated in a Tank Rise/Fall equation?

Answer 13

Volume change = flow rate x time (= Q x t)

Question 14

What is the gallons-per-foot equation in Tank Rise/Fall?

Answer 14

gallons per foot = 0.785 x D x D x 1’ x 7.48

Question 15

How many gallons-per-foot are there in a tank with a 1-foot diameter? Not memorized. Use a calculator.

Answer 15

5.8718 gallons

Question 16

What does GPCD mean?

Answer 16

Gallons Per Capita per Day

Question 17

What are the units of GPCD?

Answer 17

gallons-per-day per person

Question 18

How is GPCD determined?

Answer 18

Divide the average daily gallons used in a District’s service area by the population served

Question 19

How do you calculate Water Loss?

Answer 19

Subtract the gallons measured at the meters from the total gallon-output in the system to get the total gallons lost. Then see what percentage the gallons lost is of the total water output. Gallons lost divided by total output, multiplied by 100.

Question 20

What is Peak Demand Factor?

Answer 20

A ratio between the maximum water usage (peak demand) during a specific time period, compared to the average water usage.

Question 21

What are the units of Peak Demand Factor?

Answer 21

It doesn’t have any because it’s a ratio.

Question 22

What is the equation for Peak Demand Factor?

Answer 22

PDF = Peak/Average

Question 23

How do you convert feet of head to psi?

Answer 23

Divide feet of head by 2.31

Question 24

How do you calculate sidewall pressure?

Answer 24

Depth in feet multiplied by 62.4 pounds per cubic foot

Question 25

How do you convert psi to feet of head?

Answer 25

Multiply psi by 2.31

Question 26

How many feet of head are there on the side of a tank at a depth of 25 feet?

Answer 26

25 feet of head

Question 27

How do you calculate specific gravity?

Answer 27

Density of a solid or liquid divided by the density of water.

Question 28

What is the density of water?

Answer 28

62.4 pounds per cubic foot

Question 29

What is the specific gravity of air?

Answer 29

0.075 pounds per cubic foot

Question 30

How do you calculate pressure in pounds per square foot?

Answer 30

depth times 62.4 pounds per cubic foot

Question 31

How do you calculate hydrostatic force?

Answer 31

Pressure times Area

Question 32

1 horsepower is equal to how many ft-lbs/min?

Answer 32

33,000 ft-lbs/min

Question 33

1 horsepower is equal to how many ft-lbs/s?

Answer 33

550 ft-lbs/s

Question 34

How do you convert ft-lbs/min to horsepower?

Answer 34

Divide by 33,000

Question 35

1 horsepower is equal to how many watts and kilowatts?

Answer 35

1HP = 746w and 0.746kW

Question 36

How do you determine the percent strength of a solution by weight?

Answer 36

Weight of the solute divided by weight of the solution, multiplied by 100.

Question 37

How do you determine weir overflow rate?

Answer 37

Weir flow (gpd) divided by Weir length (ft)

Question 38

How do you determine Surface overflow rate?

Answer 38

Flow (gallons per day) divided by tank surface area (sqft)

Question 39

How do you determine filter loading rate?

Answer 39

Flow (gpm) divided by filter surface area (sqft)

Question 40

How do you convert gpm/sqft to inches of waterfall/minute?

Answer 40

Multiply by 1.6

Question 41

The filter backwash rate is the same equation as what?

Answer 41

The filter loading rate

Question 42

1 gpm/sqft is equal to how many inches per minute?

Answer 42

1.6 in/min

Question 43

What is the minimum oxygen content for a confined space?

Answer 43

19.5%

Question 46

Where in a chlorine storage facility should ventilation system intake be located?

Answer 46

Lowest point in the room typically 12 inches from the floor

Question 47

What program/documents provide the employee with pertinent information of hazardous substances in the workplace?

Answer 47

SDS: Safety Data Sheet

Question 48

What's the nominal percentage of oxygen in a room?

Answer 48

20.9%

Question 49

What is the minimum and maximum chlorine residual in the distribution system?

Answer 49

O.2 - 1 mg/L 4 mg/L

Question 51

What is the minimum pressure in a distribution system?

Answer 51

20 psi

Question 52

What is turbidity measured in?

Answer 52

Nephelometric Turbidity Unit NTU

Question 53

What is max turbidity for drinking water?

Answer 53

0.3 Nephelometric Turbidity Units

Question 54

What is used to neutralize chlorine and how is it available?

Answer 54

Sodium Thiosulfate Na2O3S2 in tablets and granular

Question 55

What size tanks is liquid chlorine available?

Answer 55

1 ton and 250 lbs

Question 56

What are 2 things from algae blooms that cause taste and odor problems?

Answer 56

2-Methylisoborneol (MIB) Geosmin

Question 57

What elements make water hard?

Answer 57

Calcium and Magnesium

Question 58

How are TDS and Conductivity related?

Answer 58

TDS (ppm) is roughly half of Conductivity (microsiemens / centimeter

Question 59

Gaseous chlorinators feed in what units?

Answer 59

Pounds per day

Question 60

How long are bacteriological sample results kept on file?

Answer 60

5 years

Question 61

What size sample do you need for a colilert test?

Answer 61

100 ml

Question 62

What temperature is the incubator set at for a colilert test?

Answer 62

35⁰ C