WR Problems

[Guest]

1. Where is the most common location of leaks on old service connections?

a. Household plumbing

b. Connections to the curb stop

c. Connections to the gate valve

d. Pressure regulator

2. What is the pressure head on a system exerting a static pressure of 62 psi?

a. 27 ft

b. 89 ft

c. 143 ft

d. 175 ft

3. A hypochlorite solution is being pumped from a small tank that is 2.0 ft in diameter. The level in the tank drops 2.25 ft in 4 hrs. How many gpm of hypochlorite solution were used?

a. 0.22 gpm

b. 0.53 gpm

c. 2.2 gpm

d. 5.3 gpm

4. Which of the following is a difference between convential filters and greensand filters?

a. Greensand granis are larger than conventional silica grains

b. Greensand filters remove iron and manganese by adsorption and oxidation

c. Conventional filters remove iron and manganese by adsorption and oxidation

d. Conventional beds must be regenerated during backwash

5. Alkalinity consists predominantly of which of the following?

a. Bicarbonate, carbonate, and hydroxide

b. Carbon dioxide and bicarbonate

c. Carbonate and carbon dioxide

d. Carbonate, carbon dioxide, and bicarbonate

6. Hard water scale is usually caused by

a. Calcium bicarbonate

b. Calcium carbonate

c. Magnesium bicarbonate

d. Magnesium carbonate

7. What should the setting on a chlorinator in lbs/day, if the dosage desired is 2.90 mg/L and the pumping rate from the well is 975 gpm?

a. 29 lb/day

b. 34 lb/day

c. 41 lb/day

d. 336 lb/day

8. What is the minimum contact time when using chlorine tablet method of disinfection for new water mains where the water is greater than 41 F?

a. 6 hr

b. 12 hr

c. 18 hr

d. 24 hr

You can PM me for answers.

JR

 

[civilsid]

Here's my answers, some of which are sure to be right!

1. I'm not sure but my knee jerk reaction is the plumbing in the home. But my exam answer is at the pressure regulator because a) the pressure is higher at the pressure regulator which is more conducive to leaks. I say "D"

2. 2.3 feet per psi. "C" (take pressure in psi, convert to psf- multiply by 144 and divide by the density of water 62.4 lb/ft^2)

3. "A" volume is 2.25 * pi. divide by 4 hours to get 1.767 ft^3 per hr convert hours to minutes and feet to gallons. .22

4. "B" I actually got lazy and did an interntet search to find that greensand filters are specifically advertised for removal of FE, Mn, and H2S.

5. "A" Alkilinity is caused by negative ions. carbon dioxide is not an ion.

6. "B" by looking in CERM and knowing that scale is calcium based. CERM pg 25-4 line 1 "...can be heated to precipitate carbonate as a scale."

7. "B" 2.9 mg/L multiply by 8.34 to get = 24.186 lb/MG ... ... ... 975 GPM = 1.4 MGD easy math

8. "D" I found lots of info but nothing about using tablets for chlorine disinfection of water mains so I will go with the most conservative answer. "D"

 

[Guest]

Here's my answers, some of which are sure to be right!

Not bad civilsid .. the only one you appear to have missed is #1. I don't have my answer sheet but based on responses to other inquiries, it appears you only missed #1 -- the answer is b. I am sure you are right on the others, except maybe #8 .. but as I recall #8 was NOT b .. and the answer looks like you are in the ballpark.

Excellent !!! :Locolaugh:

JR