Item 5 - Ratify MWMC Budget - Laserfiche WebLink

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WET WEATHER MANAGEMENT PLAN 3.4 Key Study Decisions Several key decisions were made as part of the CAC process in addition to the recormnenda- tion of the selected alternative. Many of these decisions and observations regarding the elements of the WWFMP and its implementation were developed into formal policy statements that are induded in Section 7. A summary of the decisions, which mirror many of the policy statements, is included in this section. The decisions and resulting policy statements were originally developed by the CAC and then refined through review by the project steering committee. "Perpetual" system rehabilitation: This refers to the need to perform ongoing system. rehabilitation, which results in no increase and potentially a decrease in systemwide I/I , from existing levels. It also provides the benefit of maintaining the physical condition of the system. Implementation of a.voluntary, private lateral replacement program: This was considered to be an essential component of the WWFMP. Even though a solution was identified where only the public portion of the system requires rehabilitation, the private portion contributes a significant portion of the I/I and therefore must be addressed. Although the details of implementing such a program were not the charge of the C. AC, several recommendations for program elements were developed and are included in Section 7. Secondary treatment process at the regional plant: The CAC recommended that the secondary treatment capacity should be increased to 130 mgd. This level was based on the frequency of flows that would exceed 130 mgd and the cost and benefits of increasing treatment levels beyond 130 mgcl. An increase to 130 mgd is consistent with a previous recommendation in the Master Plan for the Eugene/Springfield Water Pollution Control. Collection system performance: The number of overflows over time should be monitored and used to assess the need for modifications to system improvements or to identify needs for adjustments to the criteria used to develop peak flows that drive improvement sizing. For example, regional climate changes may result in refinements to the dofiuition of the 5-year-fr. equency design storm. Changes in precipitation pathm~ should therefore be monitored and modifications made to the characteristics of the design storm as warrantecL Any basement flooding that occurs in the system should be investigated and eliminated through system improvements, operations, or by providing back flow-prevention devices to property owners on an individual basis. SSOs for rainfall events in excess of the F-year design storm: Under these circums~ces, overflows should be directed to controlled locations along the Willamette River to maximize protection.of public health and property by minimizing direct public exposure. Flow monitoring of Iii levels and pre- and post-rehabilitation I/I levels: The project team used the best available data to estimate flow rates' and flow reduction quantities resulting from rehabilitation. However, because these are estimates based on a limited number of storm events and system rehabilitation work, they should be evaluated as part of the ongoing evaluation of system performance.