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<br />Table 1
<br />
<br />Construction Costs of Various Flood
<br />Proofing Alternatives
<br />
<br />Design Alternatives No Flood Wet Flood Raised on Partially Raised Raised on
<br /> Proofing Proofing Fill with Watertight Columns
<br /> Closures
<br />Basic Build,ng Cost $562,812,00 $562,812,00 $562,812,00 $562,812,00 $562,812,00
<br />Per Square Foot a 25,01 25,01 25,01 25,01 25,01
<br />Net Costs Associated with
<br />Flood Proofing $ 46,915,00 $ 35,912,00 $ 89,732,00 $ 87,923,00
<br />Per Square Foot 2,09 1,60 3,99 3,91
<br />Total Cost $562,812,00 $609,727,00 $598,724,00 $652,544,00 $650,735,00
<br />Per Square Foot 25,01 27,10 26,61 29,00 28,92
<br />Average Annual Costs b
<br />Basic Building Cost $ 52,398,00 $ 52,398,00 $ 52,398,00 $ 52,398,00 $ 52,398,00
<br />Per Square Foot 233 2,33 2,33 2,33 2,33
<br />Net Costs Associated with
<br />Flood Proofing $ 4,368,00 $ 3,343,00 $ 8,354,00 $ 8,186,00
<br />Per Square Foot 0,19 0,15 0,37 0,36
<br />Total Cost $ 52,398,00 $ 56,766,00 $ 55,741,00 $ 60,752,00 $ 60,584,00
<br />Per Square Foot a 2,33 2,52 2.48 2,70 2,69
<br />
<br />aArea of building is 22,500 square feet.
<br />bAssuming: A 20 year life of improvements with no salvage value; and
<br />100 percent financing of all improvements at a 70/0 interest rate per year for 20 years at a constant payment rate (debt retirement rate)
<br />of 9.31 ~:o per year.
<br />
<br />Insurance Premiums
<br />
<br />Actuarial insurance rates are determined by the height of
<br />the first floor elevation of a structure, as previously dis,
<br />cussed, Since wet flood proofing does not change the
<br />first floor elevation of the structure, the insurance pre-
<br />miums for the basic building (no flood proofing) and the
<br />wet flood proofed building are the same,
<br />
<br />The annual insurance premiums for the five buildings are
<br />detailed in Table 2, The annual insurance premiums for
<br />maximum coverage in the Regular Program at actuarial
<br />rates are: $20,795 for the buildings at grade; $1,215for
<br />the building partially raised on fill and flood proofed to
<br />one foot above the base flood level; $575 for the building
<br />raised on fill to one foot above the base flood level; and
<br />$235 for the building raised on columns to six feet above
<br />the base flood leveL23 Thus, flood proofing through
<br />elevation or watertight closures reduces insurance pre-
<br />miums considerably.24
<br />
<br />Benefit/Cost Ratios.
<br />
<br />The present value of the reductions in the annual insur-
<br />ance premium for each alternative is computed by sub-
<br />tracting the present value of the cost of insurance of
<br />each flood proofing alternative from the present value of
<br />the cost of insurance to the basic building without flood
<br />proofing (for example, the annual reduction for the build-
<br />ing raised on fill is $220,302- $6,092 ~ $214,210),
<br />Thus, there is no net benefit in reduction of insurance
<br />premiums gained by wet flood proofing, For flood
<br />proofed alternatives in conformance with National Flood
<br />Insurance Program regulations the annual reductions of
<br />insurance premiums are as follows: $19,580 for the
<br />building raised on fill and equipped with watertight clo'
<br />sures; $20,200 for the building elevated on fill; and
<br />$20,560 for the building eievated on columns, The pre,
<br />sent values of these reductions are $207,430, $214,210
<br />and $217,812, respectively,
<br />
<br />19
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