Final Draft - Wastewater Collection System Capacity Analysis Apprendix A April, 1999

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Final Report City of Paris, Texas Wastewater Collection System Capacity Analysis Basin Ranking, Alternative Projects and Costs Summary Basin Ranking To determine the best combination of funding required for the restoration of hydraulic capacity to the system, various scenarios of replacement and rehabilitation were considered. Rehabilitation programs reduce extraneous flows into the system from defects and may subsequently reduce the funding requirements for replacement pipes. By evaluating these combinations, we can determine the best piping investments required to restore capacity to the collection system. In general, the overall capacity of the system is sufficient to handle dry weather flows, but becomes overloaded during rainfall events. The inability of the system to convey wet-weather flow is caused by a combination of insufficient hydraulic capacity and leaks in the system. This inadequacy creates conditions conducive to overflows and bypasses. To address these operational problems, hydraulic modeling was used to evaluate various combinations of replacement and repair. Cost estimates were prepared for each alternative and the overall effectiveness in restoring system capacity was considered. Physical inspection was performed on the system to determine the location and nature of the system defects. Cost and flow reduction estimates related to potential rehabilitation programs were prepared from the information gathered during this phase of the project. During the flow momtoring of the system, increases in the flow related to rainfall were recorded. In those basins with observed wet weather response, the majority of the defects are of the inflow type which are comparatively inexpensive to repair. This information is also included in the collection system model which identifies areas where the pipes need to be larger to convey the flow. Basin priorities for future work were based on the combination of hydraulic replacements required and basin response to observed rainfall events. The basins are ranked into 3 categories. These are: • Top Priority (Capacity deficiencies and defect flow response) • Medium Priority (Capacity deficiencies and rehabilitation needs) • Low Priority (Basins with little or no capacity deficiencies) These rankings are presented in Table 1 and are shown on an overall map of the system in Figure 1. Note that these priorities are likely to be different from other portions of the report as they consider costs of both pipe replacements and observed defect flow response. 2