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Sanitary Sewer Overflow Prevention and Mitigation

Sanitary Sewer Overflow (SSO) Prevention and Mitigation

SSO prevention is our main goal in collection system operations. All other activities fall second to this primary goal of zero overflows. It is this level of importance which drives a utility to provide a better and more comprehensive program of maintenance through the cMOM audit (see our section on cMOM audits) to reach the ultimate goal.

SSO prevention is not limited to simply cleaning problem lines periodically. It demands a management discipline that seeks to find the root causes of these problems in the system and ultimately solve them over time. As with any process, however, competing interests in management and operations can cause attention gaps in the preventive process, which then requires automation in the work order system and data management of the utility.

Some utilities can find themselves in reversing trends, going from a low number of SSO events over a period of time, to a much higher number over a short period. Some of these can be explained by weather phenomenon which may create unusual circumstances extraneous groundwater in the system, but the end result are SSOs which need to be addressed regardless of cause. SSOs, however, do happen, even in the most well managed systems. When they do, mitigation is then the first step that has to be made in response to the spill, be it small and easily contained or cleaned, to very large with millions of gallons involved.

Tilson & Associates has various programs that can be initiated to help get ahead of growing SSO events, keep SSO events low over time, and/or mitigation efforts if they occur. Our programs have demonstrated success in utility operation and management and employ sound best practices tailored for the utility and its compliment of manpower, equipment, and expertise.

Manhole Inspection Program

Manhole inspection should be a staple of any collection system maintenance program. This is a fairly routine process of recording manhole conditions each time one is opened by anyone in system operations or engineering. However, many utilities do not involve this process into their routine data collection for a number of reasons, paperwork issues being chief among them.

If SSOs are increasing, there is no faster way to get in front of the issue than manhole inspections. Though seemingly simple sounding, there are some elements to this that need to be understood by both managers and field personnel alike, which requires some education and set up prior to initiating a successful program that yields demonstrated results.

Tilson & Associates has programs which can be implemented in accordance to need, manpower availability, and sophistication that can be very effective in reducing SSOs and potential conditions they develop in. These programs can provide a wealth of information, depending on how they are initiated, and once in place, can quickly become routine in operations once it is folded into the tasking elements of field work.

Preventitive/Predictive Maintenance Programs

Collection system maintenance for many years was considered a back burner issue with many utilities. Response based maintenance was used to respond to SSO calls or service connection back ups, to relieve the blockage in the sewer main and clean the line just up and down stream from the affected line section.

Today's collection system has to be more proactively managed, it is no longer acceptable to perform management by crisis in these systems. To do so invites regulatory actions that can be very stiff in terms of fines or compliance orders that can be difficult to achieve. Preventive maintenance is the first step of a two step process, the second being predictive maintenance.

A preventive maintenance (PM) program utilizes a number of things in a utility, system records and historical information, operator and management experience in the system, and technology to manage the process of sorting and recall. Every utility has a threshold of performance in this process, some utilities are not able to muster more than a very basic PM program consisting of a list of “hot spots” that need to be cleaned once a month, others may have a highly sophisticated PM program that anticipates various weather or population system use patterns to keep specific areas cleaned in time for these events. No two systems are the same in terms of what they can use in this regard.

Tilson & Associates can help tailor preventive maintenance programs for utilities which can combine work order automation to reduce the likelihood of various areas of the system being neglected through forgetting about them. Our programs can be as basic or sophisticated as necessary to create or improve existing programs or meet compliance issues a utility may be facing. Beyond the PM program, we can help with QAQC issues with a given PM program to determine how effective it is, if personnel are performing the critical tasks necessary to keep SSOs from developing, and ensure the proper equipment is tasked to the proper jobs.

Emergency Response Procedures

The second half of the preventive maintenance program is SSO mitigation. This is an understanding there will be SSOs that occur and planning the appropriate emergency response (ERPs) for specific emergencies and/or areas or facilities they may occur in.

Emergency response is not something that should be discussed during the emergency itself, but planned out well in advance of any emergency so it can be refined and tested, especially in environmentally sensitive areas such as potable water supply reservoirs, swimming or fishing areas, areas around high populations, etc.. These are places where the public sees the utility in response mode and are likely to be highly critical if things do not go well.

Tilson & Associates can help develop the emergency response plan along with specific procedures for specific sites in the system. We bring years of experience to the table relative to finding those areas of the system that are likely to be difficult issues should they fail, such as around critical pump stations, system structures in low land areas, in easements, and high density residence and commercial areas. We develop these various response plans in view of the equipment and personnel available to the utility both during normal working hours and after hour response staffing.

This is one of the chief elements of system management that if not addressed can quickly become an issue during an emergency. In some instances, this can lead to regulator actions, culminating in an Administrative Order as some utilities have experienced. This process, coupled with standard operation procedure (SOP) development (see our SOP development section) can be a great tool when the emergency planned for occurs and people can follow a well thought out plan of response and post event clean up or mitigation of its effects.

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