Intake siting for surface-water supply: Which combination of criteria should be satisfied when selecting the intake location?
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APlace the intake as close as possible to the treatment plant to minimize conveyance length.
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BSite the intake in the purer (cleaner, less polluted) zone of the source.
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CLocate the intake upstream of any wastewater or stormwater discharge points.
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DOn meandering rivers, prefer the concave (deep) bank where scouring reduces deposition.
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EAll of the above.
Answer
Correct Answer: All of the above.
Explanation
Introduction / Context:Correct intake location substantially reduces raw-water variability, sediment load, and pollution risk, improving treatment reliability and cost. This question tests standard siting criteria for surface-water intakes.
Given Data / Assumptions:
- An existing river/lake source with potential pollution and sediment transport.
- A downstream water-treatment plant (WTP) that benefits from shorter conveyance.
- Meandering river morphology yielding deeper concave banks.
Concept / Approach:Good siting minimizes contamination and sedimentation. Proximity reduces head losses and pipeline costs. Upstream placement with respect to discharges avoids direct pollution plumes. On meandering rivers, concave banks experience deeper flow and more consistent depths, reducing clogging from shoals/bars common on convex banks.
Step-by-Step Solution:
Evaluate proximity: shorter raw-water mains → lower losses and O&M costs.Evaluate water quality: purer zone reduces treatment challenges.Evaluate hydraulics: upstream of effluent outfalls prevents intake of diluted wastewater.Evaluate morphology: concave bank is deeper and less prone to silting of bell mouth.Verification / Alternative check:Planning manuals recommend data collection on bathymetry, sediment transport, and outfall mapping prior to intake finalization; pilot screens and model studies may be used.
Why Other Options Are Wrong:Each single criterion is necessary but not sufficient; the comprehensive, correct choice is to satisfy all listed criteria simultaneously where practicable.
Common Pitfalls:Ignoring future upstream developments; underestimating sediment dynamics; placing intakes in stagnant coves leading to algae and taste-odor issues.
Final Answer:All of the above.