Collections Systems

Question 1

What are the 11 collection system problems?

Answer 1

1. Gravity Flow- inadequate
2. Poor Construction, design, shortcuts
3. No flexible pipes or joint tightness
4. Corrosion of sewer pipes_hydrogen sulfide gas
5. Roots from plants
6. Lack of money for maintenance
7. Given to street department
8. Groundwater infiltration
9. Not reducing infiltration/flow correctly
10. Negligence, vandalism
11. Poor records.

Question 2

What are 3 reasons for collection systems?

Answer 2

1. Sanitation
   2.Innoculation
   (vaccination)
   3.Isolation

Question 3

What is operation and maintenance?

Answer 3

Not allowing wastewater to overflow into the street or into homes.

Question 4

Name 4 factors operators are responsible

for

Answer 4

1. Preserving the community’s capital investment
2. Protecting public health and safety.
3. Protecting the environment
4. Controlling O and M expenses

Question 5

What is the purpose of a wastewater collection system?

Answer 5

To collect and convey the wastewater from community’s homes and industries.

Question 6

The water carries the wastes in the form of

Answer 6

dissolved or suspended solids

Question 7

Wastewater collection systems must be properly designed and constructed to provide a water velocity of greater than

Answer 7

2 feet per second

Question 8

What strongly influences the collection system?

Answer 8

Topography-

which means
Surface contour

Question 9

Why would a storm water and wastewater system be combined?

Answer 9

To divert excess water until treated

Question 10

How is the amount of wastewater conveyed determined?

Answer 10

Analysis of present and future quantities of domestic, commercial and industrial wastewater-anticipated groundwater infiltration and surface water inflow.

Question 11

Ideally, a wastewater collection system should be designed to

Answer 11

Convey the estimated peak flow for maximum population after fully developed. (10-30 years)

Question 12

Domestic wastewater flow is calculated by

Answer 12

Multiplying estimated population times per capita flow factors-
Ranges from 70-100 gallons per person, per day.

Question 13

Wastewater flows from commercial/industrial areas are estimated how?

Answer 13

in terms of gallons per day per acre

Question 14

Inflow can be reduced by

Answer 14

sealing manhole covers that flood

Question 15

The flow of wastewater in a collection system will vary in a 24 hour period.
______ flow early am,______ flow around noon

Answer 15

minimum flow early morning

maximum flow around noon time.

Question 16

Flow measurement in a sewer pipe is based on

Answer 16

Flow rate equals velocity of flow multiplied by the cross sectional area of the flow.

Q, cubic feet/second=(Area, Sq Ft)x(Velocity, Ft/Second)

Pg 41, example 2

Question 17

Velocities in sewers should be measured:

Answer 17

In the field to be sure actual velocities are high enough to prevent the deposit of solids.

Question 18

Velocities can be measured using ____ and

_____

Answer 18

dyes or floats

Question 19

Total travel time from insertion of dye until the dye is no longer visible at the downstream manhole is noted as (_)

Answer 19

(t)

Question 20

Floats can be any objects that_____

Answer 20

can easily be seen

Question 21

The problem with using floats is ____^^

Answer 21

They get caught up

Question 22

What is the formula for velocity?

Answer 22

Velocity is feet per second

distance (ft)
_______
time (sec)

distance in feet divided by time in seconds

Question 23

Knowledge of daily and annual flow rates in a system are useful for _____

Answer 23

Planning programs for systems

Question 24

Why is a diurinal graph useful?

Answer 24

Shows condition of system and amt of inflow and infiltration.

Chart on pg 43

Question 25

A building sewer can begin outside the building or _____

Answer 25

2-10 feet from the foundation

study diagram3.2 on page 44

Question 26

Lateral and branch sewers are ____^

Answer 26

The upper ends of the street sewer components of a collection system.

Study pg. 48

Question 27

Main sewers collect wastewater of _____

Answer 27

Several lateral and branch sewers-

area of several 100 acres.

Question 28

Trunk sewers are the main ____

Answer 28

Arteries of the wastewater system

Question 29

Intercepting sewers receive

Answer 29

The wastewater from trunk sewers and convey to treatment.

Question 30

Lift stations are used in____^

Answer 30

gravity collection systems to pump wastewater to a higher elevation