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Sub-Basin DA 22 <br />Pre- vs. Post-Rehabilitation Monitoring Results <br />14 <br />0 <br />. <br /> Reduction = 43% <br /> 0 <br />12 <br />0 <br />. <br /> y = 1.52x <br />10 <br />0 <br />. <br />rn <br />E <br />8 <br />0 <br />. <br />m - <br />E <br />0 <br />0 <br />~ 6 <br />0 <br />. <br /> <br /> y = 0.87x <br />4 <br />0 <br />. <br />2 <br />0 <br />. <br /> ~ Pre-Rehabilitation <br /> o ®Post-Rehabilitation <br />0 <br />0 ~ o <br />. <br />0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 <br />Event Rainfall Volume (in) <br />Figure 16 -Sub-basin DA-22 pre- vs. post-rehabilitation event comparison (measured flow <br />vs. event rainfall) <br />DA-23 Basin <br />Seasonal Tabulation <br />Sub-basin DA-23 measured flow data from October 1995 to January 1996 were selected for <br />the pre-rehabilitation time period and from October 2002 to February 2003 for post- <br />rehabilitation. The post-rehabilitation measured flow data from November 2001 to Apri12002 <br />had a significantly different diurnal pattern and had little, if any response to rainfall as <br />contrasted to the winter 2002/2003 data. This is very likely a result of monitoring equipment <br />problems. Figure 17 is included to show the difference between the measured flow data from <br />the 2001-2002 wet season with apparent monitoring equipment problems and the 2002-2003 <br />wet season for which the monitor appeared to be working appropriately. The unreliable 2001- <br />2002 wet season post-rehabilitation data was not used in the seasonal analysis. <br />Dry weather flows were chosen during the summer months. September 23-29, 1996 was <br />chosen as a representative sample for the pre-rehabilitation time period and June 10-16, 2002 <br />as a representative sample for post-rehabilitation. <br />Table 5 presents the results of the effectiveness assessment for the DA-23 Basin. The <br />seasonal RDII reduction is estimated to be 75%. Basin DA-23 was known to have significant <br />RDII problems that contributed to the decision to rehabilitate 90% of the public system in <br />1997. A high rate of reduction was expected. <br />