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<br />2.11.02
<br />
<br />Table 10
<br />Cost Estimate Comparison for Proposed Treatment Ponds
<br />
<br /> Capital Cost' CosVc.f. o & M Cost2
<br />POND SEH USEPA SEH USEPA
<br />2 $260,468 $0.54 $251,503 $1,300 $2,490
<br />3 $337,009 $0.53 $310,570 $1,685 $3,075
<br />4 $337,009 $0.53 $310,570 $1,685 $3,075
<br />5 $239,369 $0.54 $234,569 $1,197 $2,322
<br />6 $190,416 $0.55 $192,642 $952 $1,907
<br />7 $337,009 $0.53 $310,570 . $1,685 $3,075
<br />8 $146,885 $0.56 $155,690 $743 $1,541
<br />g $293,743 $0.53 $277,602 $1,469 $$2,748
<br />10 $146,885 $0.56 $155,690 $734 $1,541
<br />11 $149,619 $0.56 $158,160 $748 $1,566
<br />12 $239,369 $0.54 $234,569 $1,197 $2,322
<br />Totals: $2,667,780 $2,592,1353 $13,386 $21,373
<br />
<br />1. Capital Cost includes engineering and construction expenses. Land cost not included.
<br />2. Includes ,mnual inspection, weed control, etc. SEH estimate is based upon 0.5% of construction cost, while USEPA
<br />estimate is based upon 0.99% of construction cost.
<br />3. Capital Cost difference is $75,645 or 2.8%.
<br />
<br />The importance of Table 10 relates to both the total capital cost comparison
<br />and unit cost (per cubic foot of storage). The SEH estimate is very close to
<br />the USEPA estimate (2.8%) for the same BMP. In addition, the unit cost is on
<br />the low end of the reported literature.
<br />
<br />The economic benefit cost is difficult to quantify from "balance sheet"
<br />perspective for this BMP. The ideal approach would specify a chain of
<br />events: pollutant loading reductions from construction of the ponds; the
<br />physical-chemical properties of the receiving streams and consequent linkages
<br />to biologic/ecological responses in the aquatic environment; and human
<br />responses and values associated with these changes. The necessary data does
<br />not exist to conduct such analysis. Instead, the benefits can be outlined in
<br />terms of:
<br />1. Effectiveness of reducing pollutant loads;
<br />2. Direct water quality impacts; and
<br />3. Economic benetits or costs.
<br />
<br />The primary function of the proposed detention ponds is to reduce pollutants.
<br />They are very effective at removing total suspended solids (often 90%+
<br />efficiency), total phosphorus (up to 60% removal) and other associated
<br />pollutants (heavy metals and hydrocarbons). Thus, their track record and
<br />
<br />City of Arden Hills, Minnesota
<br />Local Stormwater Management Plan
<br />
<br />A-ARDEN0101.00
<br />Page 48
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