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Greeley a4d Loveland Irrigation Company Agenda Item 30b Septembe 13, 2013 (Updated September 30, 2013) Page 4 of high re ervoir levels. This existing high -level outlet is believed to be over 100 years old and only three o the six gates are in operable condition. Further, even when the gates are fully closed, signifi t water leaks from the Canal into Boyd Lake though this outlet structure. Based on inspect ons by the SEO and the Company's consulting engineer URS, this structure is beyond repair and po es a dam safety concern. The box culverts are separating from the canal, have large voids along t e culverts, and there is no evidence of reinforcing in the concrete culverts. Three E Iternatives were considered as part of the feasibility report: Alterni tive I —Do Nothing: This alternative was deemed not viable due to the potential loss of system operations and dam safety issues. Alternative 2 — Temporary Repairs: This alternative included pumping grout in the undermined portion of the Boyd Lake outlet structure and patching cracks. Based on URS's inspection, any attemp to raise or move these culverts would likely cause them to deteriorate further. Therefore this alternal ve was deemed not viable. Any attempt to increase capacity of the Horseshoe Lake outlet would I ie futile without replacing the box culvertibridge of County Road 11. The replacement of the box cul vert would also require a replacement of the outlet structure therefore a temporary repair of the Ho eshoe Lake structure was deemed not viable as the structure was not intended to serve in the no desired function. Selecte Alternative 3A — Horseshoe High -Level Outlet Replacement: This alternative is to replace the entire high -level outlet structure, including the box culvert/bridge under County Road 11C. TI Lis project includes a 5 -foot tall by 44 -foot wide hinged crest gate with a 1,100 cfs capacity upstrea n of a new concrete box bridge crossing. Downstream of the new box culvert, a 108 -inch RCP pi e will be installed to convey flows downstream to a baffle chute structure and into Boyd Lake. T ie County will design, install, and fund the box culvert bridge of County Road 11 C. Althoul h the Company and Seven Lakes share responsibility and ownership of this outlet structure, the Cor ipany has agreed to take on sole responsibility for the CWCB loan as the Project Sponsor. Selectei I Alternative 3B — Boyd Lake High -Level Outlet Replacement: This alternative is to replace he entire high -level outlet structure, including the aged gate structures. The project includes the rem )val of six concrete box gate outlets and replacing them with two 48 -inch steel pipes encased in concrete. The flow will be regulated by two 48 -inch by 48 -inch slide gates that will be installe out of the dam and adjacent to the canal. The new oulet will pass a design flow of 240 cfs into the canal and also back into Boyd Lake, when required. Altemajives 3A and 3B meet the goals of this project with costs as summarized in Table 3: