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Conclusions and Recommendations <br />,. <br />l_ <br />,_ <br />I'!,( <br />(, <br />1 ~1 <br />". <br />Results of the pre- and post-rehabilitation in the form of percent reductions are presented in <br />Table 6. <br />Table 6 <br />Estimated Percent Reductions in RDII as a Result of Rehabilitation <br /> E/S WPCF Amazon Sub- Sub- Sub- Sub- <br /> Systemwide Basin basin basin basin basin <br /> (DA) DA-21 DA-22 DA-23 DA-24 <br />Seasonal RDII 15% 40-70% N/A N/A 75% N/A <br />Volume vs. Rainfall <br />Event RDII Volume 13% 40% 26% 43% 71% 59% <br />vs. Rainfall <br />Event RDII Volume <br />vs. Event +7-Day 11% 39% N/A N/A N/A N/A <br />Rainfall <br />Event RDII Volume <br />vs. Event + 30-Day 8% 29% N/A N/A N/A N/A <br />Rainfall <br />Event Peak Flowrate <br />vs. Event Maximum N/A 35% N/A N/A N/A N/A <br />Rainfall Intensity <br />The reliability of the percent reduction estimates could be improved if more data were <br />available for analysis. However, in aggregate, the results indicate that rehabilitation has been <br />successful. Positive results are apparent at all three scale levels of analysis: systemwide, <br />basinwide, and sub-basin. Particularly impressive is that reductions are apparent at the <br />systemwide level given the size of the Amazon Basin relative to the entire Eugene/Springfield <br />wastewater collection system (approximately 14% of total collection system). Systemwide <br />results also reflect successful rehabilitation efforts that have recently been implemented by the <br />City of Springfield. Springfield rehabilitation has in general proceeded in accordance with <br />WWFMP recommendations and prioritizations. However, due to a lack of reliable pre- <br />rehabilitation data, effectiveness assessments have not been conducted. Reductions that have <br />been achieved in Eugene generally exceed cited experience from agencies in other Cities and <br />States. However, comparisons are tenuous and must consider differences in extent, objectives, <br />and quality of rehabilitation practices. <br />The WWFMP report of 2000 included an estimate of achievable RDII reductions as a function <br />of rehabilitated length of pipe. This estimate was tabulated for rehabilitation of both public <br />system only and public plus private/upper laterals. The estimate was presented in Figure 5-10 <br />of the WWFMP report as a graph with rehabilitation as a percentage of total pipe on the X- <br />axis and percent reduction in RDII volume on the Y-axis. Table 7 includes the excerpt from <br />Figure 5-10 in the WWFMP report along with results achieved based on the current analysis. <br />33 <br />