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Preliminary Design Report Addendum No.2 gate provides superior hydraulics and requires less long -term maintenance activities. It should be noted that the anticipated life span of a radial gate exceeds fifty years in comparison of the rubber dam, which may need a complete replacement after fifteen years of operation. 3.1.4 Operation and maintenance Both structures can be installed in open channels. Radial gates require maintenance which includes periodic lubrication of the side racks and bearings. Comparatively, the rubber dam has a more intensive operation and maintenance schedule. The replacement costs for the rubber dam is relatively high, as it cannot be replaced in parts, but rather the whole unit would have to be replaced. Table 3- 1 Comparative Summary of Diversion Structures Radial Gate (Hydro Gate) Inflatable Dam (D rhoff Ltd. • Dimension: 8 ft high x 26.5 ft wide x 2 • Dimensions: 8 ft high x 55 ft wide x l span • hoist/operator included • Material of rubber body: • Hot - Rolled Steel (Plates, Structurals, Flat • EPDM rubber outer layer Bars) ASTM A36 or A306, Grade 60 • 2 layers of nylon fabric; • Cold- Rolled Steel (Shafting and Pins) • 1 layer of stainless steel wire mesh • ASTM A108, Grade 1045 • nominal thickness 3/8 inch • Stainless Steel (Fasteners) • Clamp plates: ductile iron • ASTM F593 or F594 Group 1 • Anchor bolts: carbon steel • Cast Iron ASTM A126, Class B • Special pipe connection flanges: stainless • Rubber: ASTM D2000, Grade 1AA625 steel 304 • Stainless Steel: ASTM Al 67 or A240, Type 304L $970,000 $380,000 Table 3- 2 Comparative Summary of Diversion Structures Costs In summary, both structures are suitable for the project. While radial gates offer benefits of superior hydraulics and clear water way, faster operation and lower maintenance requirements, its initial installation capital cost is higher than that of the rubber dam. Comparatively, the rubber dam is economically a more feasible option for this particular case. UiLS 7 25F -139 Radial Gate Inflatable Dam Initial Capital Costs $970,000 $360,000 Lifes an 60 15 Discount Rate 3.00% 3.00% Annual maintanance $6,000 $12,000 27.68 11.94 -Repayment Equivalent Annual Costs 41,049 42,156 In summary, both structures are suitable for the project. While radial gates offer benefits of superior hydraulics and clear water way, faster operation and lower maintenance requirements, its initial installation capital cost is higher than that of the rubber dam. Comparatively, the rubber dam is economically a more feasible option for this particular case. UiLS 7 25F -139