What information is essential to estimate the flow of a sanitary sewer overflow (SSO)?

To estimate the flow of a sanitary sewer overflow (SSO), it is crucial to have precise data on the spill’s start time, end time, and spill rate. Knowing the start and end times allows for the calculation of the total duration of the overflow event, which is vital to understanding how long the sewage has been released into the environment. The spill rate provides insights into the volume of sewage being released per unit of time. By combining this data, you can accurately estimate the total volume of the overflow, allowing for a better assessment of environmental impact and necessary remediation actions.

While the other options provide valuable information in specific contexts, they do not directly facilitate the estimation of flow during an SSO. Maintenance records and water quality tests focus on the systemic health of the sewer system rather than on real-time overflow scenarios. Rainfall data and city population statistics could inform broader trends affecting sewer performance but do not provide the immediate flow metrics needed for an SSO analysis. Similarly, soil type and environmental conditions may influence how sewage interacts with the environment but do not offer data specific to the flow volume during an overflow incident.