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<br />I' <br />I, <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />~..C''' , .',0 <br />t'.' f..."J <br />',' - -' <br /> <br />NITRIFICATION ALTERNATIVES <br /> <br />Alternatives to in-plant nitrification were developed from a comprehensive survey of non-traditional <br />techniques which could be used singly or in various combinations. For the purposes of this study, a <br />'non-traditional technique" is defined as a conceptual means, other than nitrification at the South <br />Complex, to meet Segment 15 water quality standards. Based on an extensive literature review, <br />seven techniques were identified as potentially viable for application to Segment IS. These included <br />the following: <br /> <br />· Stream channel modifications <br />· Artificial in-stream reaeration <br />· Water reuse/exchanges <br />· Dilution <br />· Land-based treatment <br />· Effluent diversion to irrigation ditches <br />. Filtration of Central Plant effluent <br /> <br />Each technique was modeled through an iterative process in which greater degrees of technique <br />refinement and implementation were simulated until compliance with the Segment IS DO standard <br />was able to be approached in an optimum manner, The strengths and weaknesses of each technique <br />were assessed, and this assessment served as the basis for combining techniques into alternatives, <br />T.l/;enty~ight alternatives were identified for funher modeling and qualitative screening, based on the <br />following four criteria: implementability, operational and reliability concerns, environmental <br />compatibility, and potential for public support. This evaluation process resulted in the selection of the <br />eight preferred alternatives presented in Table ES-l. These eight preferred alternatives were <br />subjected to further refinement and water quality modeling. Capital and operating and maintenance <br />(0 & M) cost estimates were prepared for each. <br /> <br />Six of the eight preferred alternatives could result in a significant cost savings to the District <br />compared to the construction of nitrification facilities at the South Complex, In particular, <br />Alternatives A I, A2 and B have estimated capital costs ranging from 532 to 544 million versus $72 to <br />$112 million for construction of nitrification facilities at the South Complex. Water rights and plant <br />effluent quality acceptable 10 the irrigation companies may affect the District's ability to implement <br /> <br />D-6 <br />