Understanding the components of a sewerage system is important for civil engineering. This question asks us to match different parts of a storm water collection system with their primary functions. Let's analyze each component and its role.

Understanding Storm Water System Components

The items listed are common elements found in systems designed to collect and manage storm water runoff.

• Storm water inlets: These are openings in the street or ground surface that allow surface water runoff directly into the storm sewer system. They are the first point of entry for rain water.
• Catch basins: These are structures similar to inlets but include a sump or trap below the outlet pipe. This sump is designed to capture sediment, debris, and other heavy solids carried by the storm water, preventing them from entering and clogging the main sewer lines.
• Flushing manholes: These are special manholes typically located at the beginning (head) of a sewer line, especially for smaller sewers. They are designed to allow for periodic flushing of the sewer line by accumulating water or by manually introducing water to clear out settled solids and prevent blockages.

Matching Components to Functions

Based on the functions described for each component, we can now match them with the descriptions provided:

1. Storm water inlets: Their primary function is to collect surface runoff. This matches description 'a', which states "Provided to admit the surface runoff to sewers".
2. Catch basins: These are specifically designed to trap heavy debris and sediment. This matches description 'c', which states "Provided to stop the entry of heavy debris present in the storm water into sewers".
3. Flushing manholes: These are usually placed at the start of a sewer line for maintenance purposes like flushing. This matches description 'b', which states "Provided at the head of sewers".

Therefore, the correct matching is:

This gives us the pairing 1-a, 2-c, 3-b.

Revision Table: Sewer System Components

Additional Information on Sewer Systems

Sewer systems are networks of underground pipes designed to transport wastewater and/or storm water. They are crucial for public health and environmental protection.

• Sanitary Sewers: These systems collect wastewater from homes, businesses, and industries. This wastewater is then treated before being discharged or reused.
• Storm Sewers: These systems collect storm water runoff from rain and melting snow. This water is typically discharged directly into rivers, lakes, or other receiving waters, sometimes after minimal treatment.
• Combined Sewers: In older systems, sanitary sewage and storm water are collected in the same pipe network. This can lead to Combined Sewer Overflows (CSOs) during heavy rainfall, where untreated sewage mixed with storm water overflows into receiving waters.
• Appurtenances: Structures like inlets, catch basins, manholes, and flushing devices are called sewer appurtenances. They provide access, collection points, or maintenance facilities for the sewer network.