#INFOSWMM

Tutorial 13 How are the Costs Used in the LID Candidate Table for InfoSWMM Sustain?


Tutorial 13 How are the Costs Used in the LID Candidate Table for InfoSWMM Sustain?

There are seven type of costs associated with a LID or SuDS in InfoSWMM Sustain as shown in the following table.

Type of Cost Description of Cost
Linear Cost Cost per linear unit of the LID or SuDs or $/foot or $/meter. Linear is Unit Area / Unit Width
Area Cost Cost per area of the LID $/foot^2 or $/meter^2
Total Volume Cost Cost per volume of the LID $/foot^3or $/meter^3
Soil Media Volume Cost Cost per volume of the LID $/foot^3or $/meter^3
Under Drain Volume Cost Cost per volume of the LID $/foot^3or $/meter^3
Constant Cost Constant Cost per Unit or Replicate
Percentage of other Costs Percentage of the Other Costs or Overhead/Multiplier Costs

A Good Estimate of LID or SuDS Costs

The source is https://coast.noaa.gov/data/docs/digitalcoast/gi-econ.pdf

Green infrastructure practice Cost estimate** Existing forests and wetlands It depends on value of land, opportunity costs. Stormwater wetlands Capital cost: $1 to $2 per cubic foot of storage provided. Blue roofs Capital cost: $2 to $10 per cubic foot of storage provided ($1 to $5 per square foot with a 6” depth). Green roofs Capital cost is $18 to $64 per cubic foot of storage provided ($9 to $32 per square foot with a 6’’ depth). Tree plantings Capital cost: Tree cost is about $175 to $400. Tree box filter Capital cost is about $270 to $330 per cubic foot of storage provided (includes tree box filter and additional soil). Trees are an additional cost. Permeable pavement Capital cost: For sidewalks, the cost is about $16 to $17 per cubic foot of storage provided. Bioretention (bioswales, rain gardens) Capital cost is about $7 to $60 per cubic foot of storage provided (depending on the type of bioretention). Rain barrels Capital cost is about $7 to $13 per cubic foot of storage provided.

Cost are part of the Objective Function

Cost Example 1 – Constant Cost

In this example we have a constant cost of $50 per Rain Barrel The optimum solution is 10 Rain Barrels or a total cost of $500.

Cost Example 2 – Constant Cost + Percentage of Other Cost

In this example we have a constant cost of $50 per Rain Barrel + 50 percent of other cost. The optimum solution is 10 Rain Barrels or a total cost of $750.

Cost Example 3 – Constant Cost + Linear Cost

In this example we have a constant cost of $50 per Rain Barrel + $10 – Linear Cost. We will change the area and width as we as now optimizing Cisterns. The optimum solution is 10 Cisterns or a total cost of $800 or 10 * $50 + 10*$3*$10 The linear unit is 12 feet^2/4 feet width

Cost Example 4 – Area Cost

In this example we have a constant cost of $0 per Rain Barrel + $10 Area Cost. We will change the area and width as we as now optimizing Cisterns. The optimum solution is 10 Cisterns or a total cost of $78.57

For a RB or Cistern the area of the LID is BMParea = 3.142857/4.0*length^2).

Cost Example 5 – Volume Cost

In this example we have a constant cost of $0 per Rain Barrel + $10 Volume Cost. We will change the area and width as we as now optimizing Cisterns. The optimum solution is 10 Cisterns or a total cost of $314.29

Cost Example 7 – Underdrain Volume Cost

In this example we have a constant cost of $0 per Rain Barrel + $10 Under Drain Volume Cost. We will change the area and width as we as now optimizing Cisterns. The optimum solution is 10 Cisterns or a total cost of $314.29

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