Water storage tanks and reservoirs are a critical component of distribution systems, yet they can pose a significant challenge for water utilities as they often have a negative impact on water quality. Water quality problems can develop due to low turnover and/or inadequate mixing resulting in short-circuiting.
It is costly for municipalities when sanitary sewer overflow (SSO) occurs. SSO can happen in a residential, commercial or institutional building, as well as in a street or an environmentally sensitive area. The costs of cleaning, damages, noncompliance and possible litigation are daunting. Mechanical inline flapper and swing check valves are sometimes used to stop SSO in gravity sewer lines. However, they have an inherent inability to close off against sewage debris.
It can be costly for municipalities when lift station check valves fail and leak sewage back into the wet well from force mains, although it is an everyday occurrence. Pump wear—as well as the operational expense of inspecting, cleaning, repairing and maintaining check valves—is well documented. Also understood is the expense of force main sewage backflow into the wet well having to be pumped multiple times. This paper is a brief discussion of the techniques and use of inline duckbill all-elastomeric check valves to prevent force main sewage backflow.