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• The average TKN concentration at the Study Area's discharge point into the <br />Lateral C Canal (Sample Point E) is 1.3 times higher than the concentration in <br />the canal at Sample Point F (the canal's eastern section's discharge point into <br />the Lateral C Canal). The results imply a slightly elevated TKN concentration <br />in the Study Area. <br />Laboratory Results for Total Phosphorus <br />Total Phosphorus (TP) is the sum of inorganic phosphorus (typically referenced as <br />ortho-phosphorus) and organic and polyphosphate phosphorus. The ortho-phosphorus <br />is available for direct biological uptake. The organic and polyphosphate phosphorus is <br />generally considered unavailable for biological uptake. Therefore, any TP reduction <br />noted is most likely due to the consumption of ortho-phosphorus by canal vegetation. <br />TP concentrations at the sample points are presented in Table 4 and Figure 4. As <br />discussed, values at Sample Point A are considered unreliable. <br />TABLE 4 - 8th Street Canal TP (mg/1) <br />SAMPLE DATE <br />A <br />B <br />C <br />ID <br />E <br />F <br />9/13/2016 <br />0.19 <br />0.26 <br />0.25 <br />0.16 <br />0.14 <br />0.14 <br />9/20/2016 <br />0.12 <br />0.22 <br />0.25 <br />0.14 <br />0.15 <br />0.12 <br />9/27/2016 <br />0.26 <br />0.24 <br />0.24 <br />0.20 <br />0.17 <br />0.20 <br />9/30/2016 <br />0.07 <br />0.24 <br />0.25 <br />0.15 <br />0.14 <br />0.13 <br />10/4/2016 <br />0.06 <br />0.25 <br />0.25 <br />0.16 <br />0.14 <br />0.19 <br />10/11/2016 <br />0.05 <br />0.24 <br />0.29 <br />0.19 <br />0.19 <br />0.46 <br />10/18/2016 <br />0.08 <br />0.21 <br />0.20 <br />0.15 <br />0.13 <br />0.18 <br />10/25/2016 <br />0.06 <br />0.20 <br />0.22 <br />0.13 <br />0.15 <br />0.14 <br />11/1/2016 <br />0.10 <br />0.29 <br />0.22 <br />0.14 <br />0.11 <br />0.07 <br />COUNT <br />9 <br />9 <br />9 <br />9 <br />9 <br />9 <br />AVERAGE 1 <br />0.11 <br />0.24 <br />0.24 <br />0.16 <br />0.15 <br />0.18 <br />FIGURE 4 - AVERAGE TP ALONG <br />CANAL (mg/1) <br />0.3 <br />0.25 <br />- <br />0.2 <br />- <br />0.15 <br />0.1 <br />---- <br />0.05 <br />-� <br />0 <br />A B C D E F <br />Data indicates that the greatest average TP concentrations occur between Sample <br />Points B and C, sharply decreasing between Sample Point C and Sample Point D, with <br />an additional slight decrease between Sample Point D and Sample Point E. Average <br />TP at the eastern section of the 8th Street Canal's discharge into the Lateral C Canal is <br />only slightly greater than the discharge concentration from the Study Area. <br />The WRWWTF is a tertiary treatment plant, meaning that under normal operating <br />conditions, it produces a flow to its downstream wetland treatment system of 1.00 mg/I <br />TP or less. The treatment plant's biological processes should remove most of the <br />inorganic phosphorus present in the wastewater it receives. However, the type of <br />phosphorus present in the canal water was not determined in the study. The average <br />TP concentration between Sample Points B and C is relatively constant, indicating little <br />additional TP loading in that canal section. The data points in Table 4 indicate that <br />individual high TP readings switch back and forth between the two sample points. As <br />the water flows east in the canal toward its discharge into the Lateral C Canal, average <br />TP concentrations decrease, indicating either dilution from other water inputs or uptake <br />of inorganic phosphorus by plants, or both Average TP drops by 0.08 mg/I from Sample <br />8 <br />FAPublic Works\KeithM\Stormwater Projects\IRFWCD 8th Street Canal Water Study\Memo 2 - 8th Street Canal.doc 39 <br />