Best Management Practices (BMPs): Costing

There are many factors which will affect costs of BMPs, from soil conditions to labor rates. Therefore, the U.S. EPA parameters in the table below should be considered as estimates only.

BMP Type

Typical Cost

($/cf, or linear foot)

 Typical Cost ($/BMP) Typical Application Reference:
Retention and
Detention (1)		 0.50-1.00 $100,000
 50-Acre Residential Site
(Impervious Cover =
35%)		 Adapted from Brown and
Schueler (1997b)
Constructed
Wetland (2)		 0.60-1.25 $125,000 50-Acre Residential Site
(Impervious Cover =
35%)		 Adapted from Brown and
Schueler (1997b)
Infiltration
Trench (3)		 4.00 $45,000 5-Acre Commercial Site
(Impervious Cover =
65%)		 Adapted from SWRPC
(1991)
Infiltration
Basin (4)		 1.30 $15,000
5-Acre Commercial Site
(Impervious Cover =
65%)		 Adapted from SWRPC
(1991)
Sand Filter (5) 3.00-6.00 $35,000-$70,000 5-Acre Commercial Site
(Impervious Cover =
65%)		 Adapted from Brown and
Schueler (1997b)
Bioretention (6) 5.30 $60,000 5-Acre Commercial Site
(Impervious Cover =
65%)		 Adapted from Brown and
Schueler (1997b)
Grass
Swale (7)		 0.50 $3,500 5-Acre Residential Site
(Impervious Cover =
35%)		 Adapted from SWRPC
(1991)
Filter Strip (8) 0.00-1.30 $0-$9,000 Filter Strip $0-$9,0003
5-Acre Residential Site
(Impervious Cover =
35%)		 Adapted from SWRPC
(1991)

Notes:

  1. Retention and Detention: Cost range reflects economies of scale in designing this BMP. The lowest unit cost represents approximately 150,000 cubic feet of storage, while the highest is approximately 15,000 cubic feet. Typically, dry detention basins are the least expensive design options among retention and detention practices.
  2. Constructed Wetland: Although little data are available to assess the cost of wetlands, it is assumed that they are approximately 25% more expensive (because of plant selection and sediment forebay requirements) than retention basins
  3. Infiltration Trench: Represents typical costs for a 100-foot long trench.
  4. Infiltration Basin: Represents typical costs for a 0.25-acre infiltration basin.
  5. Sand Filter: The range in costs for sand filter construction is largely due to the different sand filter designs. Of the three most common options available, perimeter sand filters are moderate cost, whereas surface sand filters and underground sand filters are the most expensive.
  6. Bioretention: Bioretention is relatively constant in cost, because it is usually designed as a constant fraction of the total drainage area.
  7. Grass Swale: Based on cost per square foot and assuming 6 inches of storage in the filter.
  8. Filter Strip: Based on cost per square foot and assuming 6 inches of storage in the filter strip. The lowest cost assumes that the buffer uses existing vegetation, and the highest cost assumes that sod was used to establish the filter strip.

Assume additional 3% per year for inflation.

Table and notes from U.S. EPA-821-R-99-012

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