This paper will provide information to planners, engineers, and owners about operation and maintenance issues and costs associated with Retention Treatment Basin facilities.
Combined sewer overflow, retention treatment basin, operations, maintenance, budgeting.
Preparation of Long Term CSO Control Plans (LTCSOP) require a cost-effective evaluation of the total cost of both constructing (capital) and operating (operations/maintenance) the various control facilities included in the Plan. While capital costs can be readily estimated based on the infrastructure required, guidance on estimation techniques for the associated O&M requirements is not available. O&M activities associated with CSO/SSO control facilities are highly variable and depend on the nature of wet weather occurrences. Operation and Maintenance of Retention Treatment Basin (RTB) facilities requires some of the same skill sets as a Waste Water Treatment Plant (WWTP) operator but with one significant difference. WWTP operators maintain equipment to keep it running and RTB operators maintain
equipment to allow it to run when needed. RTB facilities could go months without operation and then are expected to perform at peak flow rates within 20 minutes or less of a start of a wet weather event. Adequate treatment is also being applied to the overflow from the RTB. The process goes from no flow to a dynamic model then back to no flow. The RTB may also not overflow during the event only take on water and release it back to the interceptor system. This paper will provide an understanding of how to allocate resources to provide a budget to the Operation and Maintenance (O&M) of Retention Treatment Basins (RTB). The allocation of time on a RTB for O&M is 25 % for operation and 75% for Maintenance. There are also nonstaff resources required for operation and maintenance of an RTB that can have a significant impact to the budget.