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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 />with a new structure upstream of the present location to increase the flow capacity. The <br />configuration ofthe existing check structures are functioning well but the structures are structurally <br />failing and should be replaced with similar structures at their present locations. <br /> <br />A. Plan A - Big Barnes Ditch <br />Four rehabilitation alternatives were studied for Big Barnes Ditch. Both structural and non- <br />structural options were considered. There are three structural alternatives and one non-structural <br />alternative. The first structural alternative is repairing problem areas of the existing canal. The <br />second structural alternative involves lining the existing canal geometry with concrete. The third <br />structural alternative is reshaping the existing canal cross sections and lining certain areas with <br />concrete. The non-structural alternative is leaving the existing canal in place with no repairs. Each <br />alternative is described in more detail in the following sections. Photographs of Big Barnes Ditch are <br />located in Appendix B. <br /> <br />Plan A.1 - Existing Canal Rehabilitation <br />The first structural altemative involves repairing the existing deficiencies of the canal with no <br />change in the existing discharge capacity. Field inspections revealed cracking and uplifting of the <br />existing concrete lining. Also, seepage was ob$erved along the right embankment of the benched <br />section downstream of the North Wilson Avenue Bridge. The canal lining would be repaired or <br />replaced and concrete lining would be added in the area seepage was observed. Repairing the lining <br />would eliminate the current seepage problems. The maximum discharge capacity would remain at <br />its present capacity of 550 cfs. <br /> <br />Plan A 2 - Concrete Lined Canal for Existing Geometry <br />The second structural alternative would involve lining the entire length of the canal with <br />concrete. The existing concrete lining would be femoved and reshaping of the entire system would <br />be completed to prepare the existing canal for lining. A new concrete lining would then be placed <br />along the entire canal length. This alternative would increase the maximum carrying capacity to 800 <br />cfs. The existing bridges have a maximum flow capacity of approximately 1,000 cfs which is <br /> <br />E:\G&LREPOR. WPD <br /> <br />29 <br />