asked 5 May 2017 asked by kk (420 points)
Can you formulate your question a bit more precisely?
Hi KK, A retention basin collects runoff from roads during a storm. It may play a double role: storage and/or primary treatment. In addition to temporarily collecting excess water, biological retention basins play an effective part in protecting receiving watercourses. These basins often rely on aquatic plants that retain and store pollutants contained in the runoff waters before dumping them into a receiving environment. A storm or combined sewer overflow is designed to evacuate exceptionally high storm flows into the receiving environment but does not mitigate the discharged load.
Good afternoon, A storm overflow is an installation in the network used to evacuate excess water into the natural environment. It is usually part of a separate sewer system and operates in the case of secondary water inflow. A retention basin stores water. Placed upstream of the treatment plant, it allows for controlling the flow to the pre-treatment inlet.