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
