ENVIRONMENTAL EFFECTS, BOTH POSITIVELY AND NEGATIVELY OF THE CREATION AND MANAGEMENT OF PUBLIC UTILITIES. WATER SYSTEMS AND REQUIREMENTS: STAGES AND STEPS FOR TREATING MUNICIPAL USE AND DOMESTIC DRINKING WATER USE.

1. EHS 415
PUBLIC UTILITIES AND
ENVIRONMENTAL HEALTH
ISSUES

2. `

3. WATER SUPPLY
AND
DISTRIBUTION

4. `
Water for
human
consumption
comes from one
of two basic
sources:

5. `

6. `
Water from a well to supply an
individual residence, well
water for farmstead
properties, and well water for
small public sector properties
that include schools, public
buildings, and small
commercial enterprises.

7. `

8. `
Municipal water systems that
provide potable water to a
wide array of commercial
property and domestic use
buildings including
apartments, condominiums,
duplex housing, and single
family dwellings.

9. `

10. A
“WATER SYSTEM”
HAS TWO PRIMARY
REQUIREMENTS:

11. `
1:
First, it needs to deliver
ADEQUATE amounts of water
to meet consumer
consumption
requirements plus
needed flow
requirements.

12. `
2:
The water system needs to
be RELIABLE; the required
amount of water needs to
be available 24 hours a
day, 365 days a year.

13. `
Every municipal water
system has to have a water
supply source that is both
adequate and reliable for
the city to be served.

14. `

15. `

16. `
Step 1: Screening
Water passes through a
series of screens designed to
remove debris such as twigs,
leaves, paper, stones, and
other foreign matter.

17. `
Screens are frequently
removed for cleaning or
are back-washed from
high-pressure pumps to
prevent clogging.

18. `
Step 2: Pre-sedimentation
While the water moves
slowly through each
reservoir, much of the sand
and silt settles to the
bottom.

19. `
Step 2: Pre-sedimentation
Treatment lines and basins
are shut down periodically
during times of minimum
domestic consumption for
cleaning.

20. `
Step 3: Coagulation
A coagulant, aluminum sulfate, is
added to the water as it flows to
sedimentation basins. Coagulants
aid in the removal of suspended
particles in the water by causing
them to consolidate and settle.

21. `
Step 4: Flocculation
The water is gently stirred
with large paddles to
distribute the coagulant.
This takes approximately
25 minutes.

22. `
Step 5: Sedimentation
The water flows into
sedimentation basins where
particles settle to the bottom.
After about 4 hours, roughly 85
percent of the suspended
material settles out.

23. `
Step 6: Filtration
Water at the top of the basins
flow to large gravity filters,
traveling through layers of small
pieces of hard coal, sand, and
gravel. The filters help remove
smaller particles from the water.

24. `
Step 7: Disinfection
This may be accomplished by these
methods:
~ Chlorine is added to kill bacteria and
viruses.
~ Ammonia also is added.
~ The chlorine and ammonia combine to
form chloramines compounds.

25. `
Step 8: Additives
Depending on the quality of
the water at this point, the
following additives may be
injected into the water stream
to accomplish the stated
benefits:

26. `
Step 8: Additives
~ Fluoride is added to reduce
tooth decay.
~ Calcium hydroxide is added
to reduce corrosion in the
pipes and equipment of the
distribution system.

27. `
Step 8: Additives
Two other additives have
been introduced into the
water supply before it
enters the water
distribution system:

28. `
1.
Chloramines were added
recently as a secondary
disinfectant because they were
considered to be more stable
and persistent compared to the
chlorine alone.

29. `
1.
Chloramines produce lower
levels of trihalomethanes, a
suspected carcinogen that
forms when chlorine mixes
with the natural organic
substances in water.

30. `
1.
Chloramines also are
favored because the have a
longer use expectancy time
in the water supply
without settling out.

31. `
2.
Some countries have
experienced a severe problem
of excessive traces of lead in
the finished water from old
lead-lined pipes in portions of
their cities.

32. `
2.
To counteract this problem,
orthophosphates have
been added to the drinking
water to reduce the lead
level.

33. `
2.
Orthophosphates form a
protective coating on
pipes to prevent lead
from leaching into the
water.

34. QUALITY OF
WATER

35. `
Water must be treated or
purified to meet
Regulatory Requirements
established by the EPA .

36. THE REQUIREMENTS ARE
DIVIDED INTO 2 CATEGORIES:

37. `
a.
Residential
communities with
populations not
exceeding 3,000

38. `
b.
Combined residential
and commercial
communities that serve
a population demand
over 3,000.

39. `
QUANTITY OF
WATER

40. `
The quantity of water must be
adequate to meet consumer
consumption and fire-flow
demands at any time of the
day, day of week, and week of
the year.

41. `
Maintaining a continuous or
uninterrupted supply of water for
municipal demands is a major
challenge to many municipalities
because of the following
conditions:

42. `
Droughts

43. `
Growing demands
that cannot be met
by the treatment
plant;

44. `
Lack of adequate
storage capacity;

45. `
Other communities
drawing water from the
same supply sources
such as a lake or a river;

46. `
A major commercial fire
or wild land/urban
interface fire that
exhausts the water
supply

47. `
Undetected
underground leakage
on the pipe
distribution system.

48. `