Sanitary sewer evaluation of inflow/infiltration reduction techniques.

摘要

Substantial savings in operations can be achieved by reducing the amount of wastewater that must be pumped and treated. Utilities have long dealt with the infiltration and inflow (I and I) issues in their system by televising their pipes and identifying leak points, but this primarily addresses only the infiltration part of "I and I." Inflow, which creates hydraulic issues during rain events, leads to sanitary sewer overflows and can subject the utility to fines from regulatory agencies. As a result, dealing with the inflow portion of I and I is needed. The goal of this thesis is to differentiate inflow and infiltration from baseflow and to determine the effectiveness of different methods used to reduce inflow and infiltration in sanitary sewer lines. An analysis was conducted on the benefits and cost effectiveness of different inflow/infiltration approaches (slip-lining sewer lines, stormwater manhole inserts, replacing sewer lines, smoke testing, etc.) and cost savings municipalities can expect to receive from each.;Unlike most other studies, which identify rainfall derived inflow and infiltration (RDII), the goal of this study was to develop a means to separate the flows into inflow, infiltration and baseflow. It was assumed that inflow into sanitary sewer lines is linearly related to rainfall and infiltration is linearly related to groundwater elevation. Based on these assumptions, inflow and infiltration could each be separated out from the wastewater flow, leaving only baseflow. Once the inflow and infiltration have been separated from the flows, pre and post flows could be compared to determine a percent reduction in both to develop a cost analysis.;The conclusions developed from this project are directly related to the method for determining the inflow and infiltration reduction, which were related to rainfall and groundwater elevation, respectively. It was shown that inflow is directly related to rainfall, and infiltration (excluding inflow) is directly related to groundwater elevations. The results of the analysis showed that inflow and infiltration correction methods were effective in removing significant amounts of inflow and infiltration from the sanitary sewer system. However, when compared to the cost to complete the construction activities, it was evident that inflow reduction was much more cost effective.