The CMOM program - Capacity Management, Operation and Maintenance – was developed by the US Environmental Protection Agency in the late 90’s. CMOM is a program of self-audit, rather than a series of reports that are designed for auditing centrally. But to qualify for a permit a utility must provide evidence to the EPA that the CMOM program is being followed. There are four major documentation requirements of the CMOM permit, and the required frequency of update of the documentation varies based on the size and complexity of the municipal wastewater collection system. Documentation requirements include:
A written summary of the CMOM Program
An Overflow Emergency Response Plan
A Program Audit Report
A System Evaluation and Capacity Assurance Plan
Further details of the requirements are given at the end of this article.
The EPA has for a number of years focused on the elimination of Sanitary Sewer Overflows, and has established a 25 year rain event as the benchmark target. CMOM is another step in this direction, asking utilities to develop formal plans to achieve that level of operation, and by implication to undertake formal capacity planning and scenario evaluation on their sanitary sewer networks.
CMOM will not vastly improve the performance of the best beyond what they would otherwise achieve – they already have a CMOM type self audit and improvement plan, and have the tools in place to support this. The greater impact will be to bring the lower performers closer to the standards of the best, which they should already be achieving in an ideal world
The implementation of the CMOM program within a utility will of course require a range of activities, but central to it will be accurate assessments of the current and future the performance of the network. It is here that Wallingford Software’s products InfoWorks CS and InfoNet are providing support to utilities across the US and around the world, and can contribute to every element of the CMOM acronym.
Capacity – the measurement of capacity and the planning of enhancements to meet the capacity requirements cannot be undertaken without accurate modeling. There is no other method for reliably ensuring this. Most utilities have access to data that represents a 1 in 25-year rain event. What many lack is a model, or if there is a model, one that accurately reflects the network’s performance at these extremes. All models are not the same, and the more simplistic models cannot reflect the flows and surcharges that will occur in extreme events. For that a proven, well calibrated dynamic model is required, of the type our clients are successfully using.
Management and Operations – most users associate modeling with capital project evaluation and optimization, but sometimes forget that modeling can also provide answers to issues of operation and management of collection systems. For example settings or timings of any control or pumping equipment, including real time control options, can be simulated and evaluated across a range of scenarios and the optimum selected, whether specified in terms of engineering performance, cost, or a combination of the two. Once a reliable model has been constructed, and this will probably have been justified by capacity planning considerations, it takes very little additional effort to run “what-if” scenarios to evaluate the outcome of different management and operations strategy and practices.
Maintenance – modeling can contribute to maintenance regimes, but this is a subject where InfoNet, the network information system, can make also make a major contribution. A repository for all asset information, including age, state of repair and performance, InfoNet is invaluable in supporting the repair/replace decisions that are at the heart of maintenance planning and implementation. On another regulatory matter, InfoNet also provides help in meeting the GASB 34 requirements for valuing assets.
New users are coming to recognize the power of modeling through the impact of the CMOM, but there are many water utilities, including our customers, who are well prepared, with their models already built. To sum up with two quotes from Wallingford customers:
“ Although there is an upfront financial investment in setting up a model, it’s far less than the cost of potential errors. I believe that, especially as programs such as CMOM move forward across the USA and identify the need for capacity improvements, a modeling approach is essential in water companies. Now, I would not want to make network decisions without the support of a model.” – Robert Fahey, Engineer, City of Clearwater
“More formal methods of budgetary control and Best Management Practice will be required, and modeling is one of these essential formal tools. I don’t see how any utility can approach the requirements of CMOM without a good model of their network.” - Jun Battad PE, Project Manager within the City of Dallas Pipeline Program
The six performance components
The program contains the following performance components for municipal sanitary sewer collection systems to help prevent and mitigate sewer overflows:
1. Development of proper management, operation and maintenance procedures and performance measurements for wastewater collection systems
2. Implementation of asset management and long-term planning geared to provide adequate system capacity for base and peak flows in the collection system
3. Documentation that all feasible steps to stop and mitigate impacts of sanitary sewer overflows (SSOs) have been taken
4. Development of procedures to notify parties with reasonable potential of being exposed to pollutants from SSOs
5. Performance of rigorous self-audits to assess the degree to which the performance measurements are being met
6. Completion of CMOM program summary reports that are supplied to the regulators and made available to the public.