Raw-water intake siting: Pick the incorrect requirement for locating a water-supply intake on a river, lake, or reservoir.
Correct Answer: It should be located downstream of the wastewater disposal (outfall) point.
Introduction / Context:Proper intake location is critical to raw-water quality and operational reliability. Intakes should minimize contamination risk and sediment/debris intake while ensuring access for operation and maintenance across hydrologic conditions.
Given Data / Assumptions:
- Surface-water source used for municipal supply.
- Typical river hydraulics with upstream–downstream gradients.
Concept / Approach:
To reduce contamination, raw-water intakes are placed upstream of wastewater outfalls and other pollution sources. They should also be close to the plant to limit pipeline cost, located in good-quality water zones, and accessible in flood events. Debris/sediment fields are avoided to reduce wear and clogging.
Step-by-Step Solution:
Identify the statement that contradicts standard siting practice: locating the intake downstream of an outfall—this is incorrect.All other statements align with accepted siting guidance.Verification / Alternative check:
Design manuals and environmental regulations emphasize buffer distances upstream of discharges where feasible, or require additional treatment safeguards if hydraulic constraints exist.
Why Other Options Are Wrong (as answers):
- (a), (b), (d), (e) are correct siting principles; they are not the “incorrect” statement.
Common Pitfalls:
- Confusing “upstream” and “downstream” relative to flow direction.
- Ignoring seasonal changes in water quality zones in stratified reservoirs.
Final Answer:
It should be located downstream of the wastewater disposal (outfall) point.