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MPPHED
Satpura Bhavan
Bhopal |
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INFO
& TENDER |
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PLANNING
BASIC DESIGN CONSIDERATIONS
In designing waste water
collection, treatment and disposal systems, planning
generally begins from the final disposal point going
backwatds to give an integrated and optimum design
to suit the topography and the available hydraulic
head, supplemented by pumping if essential. Once
the disposal points are tentatively selected, further
design is guided by the following basic design considerations
:
- Engineering
- Environmental
- Pro
- Cost
Engineering Considerations
Topographical, engineering
and other considerations which figures prominently
in project design are noted below:
- Design period, stage wise
population to be served and expected sewage
flow and fluctuations.
- Topography of the general
area to be served, its slop and terrain. Tentative
sites available for treatment plant, pumping
stations and disposal works.
- Available hydraulic head
in the system up to high level in case of
disposal to a nearby river or high tide level
in case or costal discharge or the level of
the irrigation area to be commanded in case
of land disposal.
- Ground water depth and its
seasonal fluctuation affecting construction,
sewer infiltration, structural design (uplift
considerations).
- soil bearing capacity and
type of strata expected to be met in construction.
- On site disposal facilities,
including the possibilities of seggregating
the sullage water and sewage and reuse or
recycle sullage water within the households.
Environmental Considerations
The environmental and
socio-economic impacts of a sewage treatment plant
may prove adverse during the operation stage.
Therefore, the following aspects should be considered
during design:
a) Surface Water Hydrology
and Quality
Hydrological considerations
affect the location of outfalls to rivers with
regard to protection of nearby water supply intake
points either upstream or downstream, especially
at low conditions in the river. Hydrological consideration
also help determine expected dilutions downstream,
frequency of floods and drought conditions, flow
velocities, times to downstream points of interest
navigation etc.
Surface water quality
consideration include compliance with treated
effluent standards at the discharge point with
respect to parameters like BOD, suspended and
floating solids, oil and grease, nutrients, coliforms
etc. Special consideration may be given to the
presence of public bathing ghats downstream. The
aquatic ecosystem (including fish) may also need
protection in case of rivers through minimum dissolved
oxygen downstream. uptake of refractory and persistent
substances in the food chain, and protection of
other legitimate uses to which the river waters
may be put.
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