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Figure 5 - E/S WPCF pre- vs. post-rehabilitation event comparison (measured flow vs. event <br />+ 30-day rainfall) <br />Amazon Basin (DA) <br />~ _. <br />The Amazon (DA) Basin is located in southeast Eugene in the upper reaches of the Amazon <br />drainage area. Characteristics of the basin are as follows: <br />• 4,350 total acres including 1,876 acres residential and 500 acres commercial. The <br />remainder is a combination of open space and roads. <br />• A population of approximately 20,000 people. <br />• 581,1001ineal feet of wastewater collection system pipe. <br />• 147,500 lineal feet of wastewater collection system pipe that has been <br />rehabilitated between 1997 and 2001 (25.4% of total pipe length in the basin). <br />The DA basin is drained at its downstream end by a single 54-inch sanitary sewer. A <br />~. _,> permanent meter has been maintained at this location from 1994 to the present at manhole <br />~'` j number 4278. The precise location of the meter is at the intersection of East 22nd Ave. and <br />the Amazon Creek. <br />~~; <br />~ Flow monitoring was accomplished with aMarsh-McBirney Flo-Tote series 260 with a <br />--~ 0.0083 flow site calibration. The 0.0083 value was chosen to match the flow volumes that <br />were predicted for the WWFMP model S-6 at this monitoring location. The Flo-Tote monitor <br />was used for both the pre- and post- rehabilitation monitoring. <br />Seasonal Analysis <br />Wet seasons or portions of wet seasons were chosen to compare pre- (prior to summer of <br />1996) and post- (after the summer of 2001) rehabilitation. DA basin measured flow data from <br />December 1994 to March1995 and October 1995 to March1996 were selected for the pre- <br />- ~,, rehabilitation time pen~iod and from November 2001 to April 2002 and November 2002 to <br />_. <br />February 2003 for post-rehabilitation. Dry weather flows were chosen during the summer <br />months. August 1-8, 1994 was chosen as a representative sample for the pre-rehabilitation <br />,_, , <br />_ ~, <br />' ._ ' period and August 19-25, 2002 as a representative sample for post-rehabilitation. <br />,, <br />'' ~--' Table 3 presents the results of the seasonal effectiveness assessment for the Amazon (DA) <br />Basin. The 2001-2002 and 2002-2003 wet seasons show a 40-70% decrease in seasonal RDII <br />j ~~:_ as compared to the 1994-1995 and 1995-1996 wet seasons, depending on the matrix of <br />,_ , comparison. <br />Table 3 <br />DA Basin Seasonal RDII Flow Reduction <br /> <br /> <br /> <br />otal Measured <br />Flow Volume MG Dry <br />Weather <br />Flow <br />Volume <br />MG Wet <br />Weather <br />Flow <br />Volume <br />MG <br /> <br />Rainfall <br />Accumulation <br />inches <br /> <br />Wet Weather Flow <br />Volume/ Rainfall <br />MG/inch <br />Pre-Rehabilitation <br />Dec 7, 94 to Mar 9, 95 470 201 269 12.5 21.6 <br />Oct 26, 95 to Mar 8, 96 851 292 559 38.6 14.5 <br />Post-Rehabilitation <br />Nov 1, 01 to A r 11, 02 617 297 320 36.9 8.7 <br />Nov 7, 02 to Feb 27, 03 396 207 189 29.4 6.4 <br />