water supply

1. SITE PLANNING
Water Supply :
The quality and quantity of our water
supplies are vital to our health. Clean water
is the most critical utility, a necessity even in
the most primitive settlement.
Yet while it may make the development of
a given site either feasible, costly, or
impossible.
Water Supply – Sources:
Natural Sources
Rain, snow, are precipitated upon the
surface of the earth may be considered as the
original source of all the water supplied.
Water, as source of drinking water, occurs
as surface water and ground water.
Surface water
Surface water accumulates mainly as a
result of direct runoff from precipitation
(rain or snow).
Surface water supplies may be further
divided into river, lake, and reservoir
supplies.
 Dams are constructed to create artificial
storage.
Canals or open channels can be
constructed to convey surface water to the
project sites. The water is also conveyed
through pipes by gravity or pumping.
In general, the surface sources are
characterized by turbidity, suspended solids,
some colour and microbial contamination.
Water Supply -
Sources

2. SITE PLANNING
Ground water
Part of the precipitation that falls
infiltrates the soil.
This water replenishes the soil moisture,
or is used by growing plants and returned
to the atmosphere by transpiration.
Water that drains downward (percolates)
below the root zone finally reaches a level
at which all the openings or voids in the
earth's materials are filled with water.
This zone is called the zone of
saturation. The water in the zone of
saturation is called the ground water.
Ground waters are, generally,
characterized by higher concentrations of
dissolved solids,
lower levels of colour, higher hardness (as
compared with surface water), dissolved
gasses and freedom from microbial
contamination. A well that penetrates the
water table can be used to extract water
from the ground basin.
The extraction of ground water is
mainly by:
1. Dug well
2. Dug cum bore wells
3. Infiltration galleries (aquifers)
4. Tube wells & bore wells.
Ground water that flows naturally from the
ground is called a Spring.
Water Supply -
Sources

3. SITE PLANNING
Water Supply – Sources On Site:
Dug Wells
Bore wells
Pipes lines laid by local authorities.
The pipes of a pressure system can be laid with bends
and gentle curves and so adapt easily to most layouts.
 Valves are placed in house branches where they
leave the mains and in the mains at points necessary to
cut off sections in the event of breaks. These valves must
be no more than 300m apart.
Water Supply -
Sources

4. SITE PLANNING
DRAINAGE
Storm Drainage Systems
Drainage of land refers to the methods
used to collect, conduct, and dispose of
unwanted rain water.
During a rainstorm, water is absorbed by
the soil in varying amounts and at varying
speeds of percolation, depending on the
soil’s porosity and the volume of soil above
the ground water table.
If rain falls faster than the soil is able to
absorb it, puddles form and surface water
begins to flow downhill.
The uncontrolled flow of this surface
runoff may result in erosion, flooding, or
damage to landscape and structures.
Surface Drainage

5. SITE PLANNING
DRAINAGE
Storm Drainage Systems
Storm drainage systems have as their
objective the removal of excess rain
water.
They are a substitute for natural
surface drainage and are generally
necessary only where development is
dense enough to cause excess runoff
following a rain.
Low-density developments often rely on
natural open land, but higher densities
imply more paved areas, which cause
greater runoff.
Surface Drainage
A typical drainage system begins with
the roof water from an individual building.
This water flows to roof drains and
downspouts that eventually conduct it to
the street, either directly or over paved
areas or lawns.
Once in the street, the water flows
downhill until it reaches a catch basin,
where it continues in an underground
drain line.
The drain line may lead to a concrete
channel that ultimately discharges the
original roof water, plus all other runoff, into
a lake or other body of water.

6. SITE PLANNING
Surface Drainage
Storm drainage systems are designed to
achieve the following:
1. Reduce flooding and damage by
eliminating excess rain water.
2. Reduce erosion by controlling the rate
and volume of water flow.
3. Eliminate standing water which may
lead to pollution and insects.
4. Enhance plant growth by reducing soil
saturation.
5. Improve the load-bearing capacity of
soils.
6. Cleanse the storm water by installing
native plants in drainage ways to act as
filters to remove particulates from the
flowing surface water.

7. SITE PLANNING
Surface Drainage
Underground storm drainage systems
are expensive.
Therefore, every effort should be made to
employ surface systems, such as gutters,
ditches, channels, short culverts and,
especially, spacious planting areas.
Drainage Needs
The demand for drainage is determined by
the following factors:
1. Topography. Steep areas drain quickly,
often too fast to allow for percolation.
Therefore, drainage benches or channels
should be provided above and below steep
banks to collect runoff water.
2. Type of soil. Soil type determines the
amount and speed of water absorption,
which in turn affects the runoff quantity.
3. Vegetation. Thick ground cover slows
down the rate of runoff, reduces erosion, and
reduces the need for elaborate drainage
systems.
4. Rainfall data. Local rainfall data is
necessary to calculate the frequency and
intensity of rain water to be drained.
5. Land use. In rural areas, one can
generally allow water to disperse over the
landscape.
In urban areas, on the other hand, surface
runoff occurs for short distances only and
then must be directed to sub-surface
drainage devices.
6. Size of area. The area to be drained
generally refers to those areas with limited
percolation, such as roofs, roads,
driveways, etc.

8. SITE PLANNING
Surface Drainage
Surface Drainage
Surface drainage involves the removal of
runoff water by means of surface devices
only. It is generally preferred over
subsurface systems, because it is less
expensive, it allows some water to percolate
into the ground, and the danger of clogged
pipes is eliminated.
The following are some general rules of
surface drainage:
1. Water flows as a result of gravity;
therefore, all surfaces must be sloped for
drainage.
2. Water always flows perpendicular to the
contours.
3. Good drainage requires a continuous flow.
Slow-moving water may create bogs, while
water moving too fast will cause erosion.
4. Water should always be drained away
from structures.
5. Large amounts of water should never be
drained across circulation paths.
6. Desirable slopes for surface drainage are
as follows:
Open land - 1/2 percent minimum
Streets - 1/2 percent minimum
Planted areas - 1 percent minimum to 25
percent maximum
Large paved areas - 1 percent minimum
Land adjacent to buildings - 2 percent
minimum
Drainage swales - 2 percent minimum to 10
percent maximum
Planted banks - up to 50 percent maximum

9. SITE PLANNING
Surface Drainage
Following are the most common methods of
surface drainage:
1. Swale.
Sloping areas can be drained by creating
swales, which are graded flow paths similar
to valleys.
Swales are graded around structures with
finish contours always pointing uphill and flow
paths shown perpendicular to the revised
contours.
2. Sloping plane. This is the simplest,
cheapest, and, consequently, the most
common way to drain a relatively level area.
The area tilts in one direction, so that the
water drains to the low side. Adjacent
structures are always located at the high side.

10. SITE PLANNING
Surface Drainage
3. Warped plane.
The high side is level, similar to the sloping
plane. The contours, however, are fan-shaped,
so that the entire area drains to one low
corner.
4. Gutter.
Gutters are formed by two sloping planes
that create a valley. The planes are slightly
warped so that water can run down the valley
to a collection point.

11. SITE PLANNING
Surface Drainage
5. Central inlet.
Large flat areas, especially where enclosed
(courtyards, patios, etc.) employ a central
drain toward which all surfaces slope.
The disadvantage of this arrangement is that
it requires a catch basin and sub-surface
piping to dispose of the water.

12. SITE PLANNING
Sub-Surface
Drainage
Sub-Surface Drainage
Sub-surface drainage refers to the
collection, conduction, and disposal of
water below ground level.
Runoff water flows not only on the surface,
but also below the ground surface.
Collection of sub-surface water utilizes
gravel-filled ditches and perforated drain
pipe, or drain pipe laid with open joints.
Runoff water that seeps into the earth flows
vertically through the gravel until it reaches
the openings of the drain pipe.
This pipe collects the free-flowing water and
carries it away in the direction of the
sloping pipe.

13. SITE PLANNING
Sub-Surface
Drainage
Closed sub-surface systems consist of
various fabricated collectors together with
sections of closed pipe, which are used to
carry water below grade from collection
points to disposal areas.
Such systems are useful in level areas,
since drain lines can be buried
progressively deeper, assuring an adequate
slope for drainage.
Among the common fabricated collectors are
the following:
Area drain. This device collects water from the
low point of a limited area and conducts it
directly to underground pipes. It has a
metal grate to prevent debris from entering
and clogging pipes.

14. SITE PLANNING
Sub-Surface
Drainage
Catch basin.
This is similar to an area drain, except
deeper and generally larger in order to
catch and retain sediment which may clog
the system.
Trench drain.
This device is used to collect water along a
wide strip before conducting it to
underground pipes.
It is suitable at the entrance to an
underground garage, for example, where it
collects the runoff water flowing down a sloping
driveway.

15. SITE PLANNING
Sub-Surface
Drainage
Material:
Drainage pipes are manufactured from
clay, concrete, plastic, or composition
materials.
Size & Slope:
They are rarely less than four inches in
diameter and require a minimum slope of
one percent to assure proper flow.
Culverts
Pipes which run underground beneath
roads, driveways, or paths are referred to
as culverts.
They vary in size from six inches to
several feet.
Culverts should be straight, cross the
road at right angles, and be sufficiently
strong to resist moving traffic loads.