In olden days the type of section adopted in trunk and out fall sewers was

ANS:B - horse shoe shaped

A horse shoe shaped sewer section refers to a particular type of sewer design that resembles the shape of a horseshoe. This design is characterized by a semicircular bottom with straight or gently sloping sidewalls that curve upwards to form an arch-like shape. Here's a breakdown of the features and advantages of a horseshoe shaped sewer:

1. Geometry: The horseshoe shape typically consists of a semicircular bottom, providing a smooth flow path for sewage or stormwater. The curved bottom allows for efficient flow and reduces the likelihood of sediment deposition.
2. Hydraulic Efficiency: The smooth interior surface of the horseshoe shape minimizes frictional resistance to flow, enabling efficient conveyance of wastewater or stormwater. This design helps maintain adequate flow velocities, even during low-flow conditions, which is crucial for preventing sedimentation and ensuring self-cleansing of the sewer.
3. Structural Stability: The horseshoe shape offers excellent structural stability and load-bearing capacity. The arch-like structure distributes external loads evenly along the sidewalls, minimizing the risk of deformation or collapse, especially in areas with high groundwater levels or unstable soil conditions.
4. Maintenance and Accessibility: Horseshoe shaped sewers are relatively easy to inspect and maintain due to their accessible geometry. Maintenance crews can access the sewer for cleaning, inspection, and repair activities more efficiently compared to circular or egg-shaped sewers, which may have tighter spaces or less accessible configurations.
5. Versatility: Horseshoe shaped sewers are suitable for various applications, including trunk lines, outfall sewers, and stormwater conveyance systems. They can accommodate varying flow rates and hydraulic conditions while providing reliable conveyance and hydraulic performance.