This existing intake pipe does not have facilities to control or limit intake icing events.

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1 Memorandum To: From:, Utilities Director Mark White Date: Subject: Memorandum This memorandum discusses the existing 36/42-inch raw water intake at the Evanston water treatment plant (WTP), including a discussion of typical useful life, cost of in-kind replacement, and cost of replacement with a new 54-inch intake. Existing Conditions The existing 36/42-inch intake pipe for the Evanston WTP is over 100 years old, as it was reportedly installed around The intake pipe is made of cast iron construction. The intake consists of a section of 36-inch diameter pipe that runs from shore out into Lake Michigan a distance of approximately 2,860 feet where it connects to a section of 42-inch diameter pipe that extends an additional 3,080 feet. The intake terminates in thirteen 42-inch diameter openings. Low lake level water depth over the intake is approximately 20 feet. The intake pipe is unburied and rests directly on the bottom of the Lake Michigan. The chlorine feed pipeline to the intake, which is used to limit the growth of zebra and quagga mussels, has failed within the intake pipeline and is considered non-repairable. This existing intake pipe does not have facilities to control or limit intake icing events. Cast Iron Pipe Service Life It is difficult to accurately predict the service life of a specific intake pipe installation, as local factors, such as installation, soil, and water characteristics heavily impact the ultimate service life. The American Water Works Association reports 1 that the average life of this vintage of cast iron pipe is approximately 100 years, indicating that they may typically last anywhere between 75 and 125 years. 1 Dawn of the Replacement Age: Reinvesting in Drinking Water Infrastructure (American Water Works Association, 2001)

2 Page 2 Evanston Based upon this information, it is projected that the existing 36/42-inch intake at the Evanston WTP has reached the end of its reliable life and should be replaced. Key concerns of the existing intake include the following: The 104 year service of the existing intake structure exceeds the average design life of castiron pipe; The intake is unburied at the bottom of the lake, resulting in exposure to stresses caused by wave action and to potential damage from objects, such as boat anchors; The failure of the chlorine feed line leaves this intake vulnerable to colonization by mussels, resulting in higher head loss and less reliable intake capacity; The intake is vulnerable to icing events within Lake Michigan, resulting in a potential loss of reliable water supply. Opinion of Probable Construction Cost Table 1 presents a summary of the estimated opinion of probable construction cost for the replacement of the existing 36/42-inch intake. This study-level cost estimate assumes replacement with a similarly-sized intake of pre-stressed concrete cylinder pipe buried within Lake Michigan. The estimate includes recommended improvements for zebra mussel and intake icing control. The estimate also assumes that the new intake will connect to the existing 36-inch yard piping on shore to connect to the existing North and South Screen Wells and the Low Lift Pump 4 Suction Well. Table 1 Planning Level Cost Estimate for the New Intake Scenarios Scenario Cost New 36/42-inch Intake $ 18,000,000 New 54-inch Intake $ 24,200,000 Table 1 also provides an estimated construction cost for installation of a 54-inch diameter pipe 5,940 feet in length to match the length of the existing 36/42-inch intake. The intake will be configured similar to the existing 54-inch intake, with a crib intake structure that includes a lowvelocity intake cone, a chemical feed/application system to protect the intake from zebra and quagga mussel colonization, and an electric resistance heating system to mitigate icing. It is assumed that new 54-inch on-shore raw water piping will connect the new intake to the raw water pumping system at the existing North and South Screen Wells and the Low Lift Pump 4 Suction Well. Onshore piping from the existing 36-inch intake is proposed to be demolished to make room for the new 54-inch raw water piping. Detailed cost breakdowns of the two alternatives are provided in the Appendices.

3 Page 3 The cost estimates consider general condition costs, conceptual costs; undeveloped design detail costs; contractor fees, overhead, and profit costs; change order costs; and engineering and administration related costs. It does not consider any potential environmental impact assessments or mitigations. The American Association of Cost Engineers has established guidelines for cost estimate accuracy versus project definition development level. This estimate is a conceptual-level (0%-2% project definition) cost estimate for comparison purposes only. The expected accuracy range is -30% to +50% as shown in Table 2. The Engineering News Record Construction Cost 20-City Average Index was equal to 9552 at the time of cost estimate preparation (July 2013). Table 2 Expected Accuracy Range for Capital Cost Estimates Expected Accuracy Range Cost New 36/42-inch Intake Plus 50% $27,000,000 Minus 30% $12,600,000 New 54-inch Intake Plus 50% $36,300,000 Minus 30% $16,900,000

4 Page 4 Appendix A Study Level Cost Estimate for Replacement of Raw Water Intake with 36 / 42-inch Pipe DIVISION ITEM COST 1 GENERAL CONDITIONS (10%) $917,000 2 SITE WORK Trenching and Backfill $4,160,000 36" Pre-stressed Concrete Cylinder Pipe (2,860 ft) $1,144,000 42" Pre-stressed Concrete Cylinder Pipe (3,080 ft) $1,387,000 3 CONCRETE 4 MASONRY 5 METALS 6 WOOD & PLASTICS 7 MOISTURE & THERMAL PROTECTION 8 DOORS & WINDOWS 9 FINISHES 10 SPECIALTIES 11 PROCESS EQUIPMENT 12 FURNISHINGS 13 SPECIAL CONSTRUCTION Marine Dive Crew and Equipment $1,486,000 Zebra Mussel Control $182,000 Intake Cone Heater $624,000 42" Pipe Tee Fittings $35,000 Thirteen 42" Intake Cones $156, CONVEYING SYSTEMS 15 MECHANICAL 16 ELECTRICAL SUBTOTAL $10,091,000 UNDEVELOPED DESIGN DETAILS (35%) $3,532,000 SUBTOTAL $13,623,000 CONTRACTORS FEES, OVERHEAD & PROFIT (10%) $1,362,000 CONTINGENCIES (5%) $749,000 ENGINEERING. LEGAL, AND ADMINISTRATIVE (15%) $2,248,000 TOTAL CAPITAL PROJECT COST $18,000,000

5 Page 5 Appendix B Study Level Cost Estimate for Replacement of Raw Water Intake with 54-inch Pipe DIVISION ITEM COST 1 GENERAL CONDITIONS (10%) $1,234,000 2 SITE WORK Trenching and Backfill $4,455,000 54" Pre-stressed Concrete Cylinder Pipe (5,940 ft) $2,970,000 54" PCCP From Shoreline to Shorewells $2,380,000 3 CONCRETE 4 MASONRY 5 METALS 6 WOOD & PLASTICS 7 MOISTURE & THERMAL PROTECTION 8 DOORS & WINDOWS 9 FINISHES 10 SPECIALTIES 11 PROCESS EQUIPMENT 12 FURNISHINGS 13 SPECIAL CONSTRUCTION Marine Dive Crew and Equipment $1,782,000 Zebra Mussel Control $182,000 Intake Cone Heater $520,000 54" Pipe Fittings $21, " x 54" Intake Cone with Crib Intake $30, CONVEYING SYSTEMS 15 MECHANICAL 16 ELECTRICAL SUBTOTAL $13,574,000 UNDEVELOPED DESIGN DETAILS (35%) $4,751,000 SUBTOTAL $18,325,000 CONTRACTORS FEES, OVERHEAD & PROFIT (10%) $1,833,000 CONTINGENCIES (5%) $1,008,000 ENGINEERING. LEGAL, AND ADMINISTRATIVE (15%) $3,024,000 TOTAL CAPITAL PROJECT COST $24,200,000