General cost estimation methods can be used by site planners to compare the relative construction and maintenance costs for structural BMPs. However, it is recommended that construction and maintenance budgets should be based on site specific information. Once the construction plans are created, designers could use the table below and the cost estimation worksheet. The table below lists the site components that are specific to bioretention practices. Not included in this table are those cost items that are common to all construction projects, such as mobilization, traffic control, erosion and sediment control, permitting, etc.
| Implementation Stage | Primary Cost Components | Basic Cost Estimate | Other Considerations |
|---|---|---|---|
| Site Preparation | Tree & plant protection | Protection Cost ($/area) x Affected Area | Removal of existing structures, topsoil removal and stockpiling |
| Clearing & grubbing | Clearing Cost ($/area) x Affected Area | Removal of existing structures, topsoil removal and stockpiling | |
| Topsoil salvage | Clearing Cost ($/area) x Affected Area | Removal of existing structures, topsoil removal and stockpiling | |
| Site Formation | Excavation / grading | 4-ft Depth Excavation Cost ($/acre) x Area (acre) | Soil & rock fill material, tunneling |
| Hauling material offsite | Excavation Cost x (% of Material to be hauled away) | Soil & rock fill material, tunneling | |
| Structural Components | Under-drains | Under-drain cost ($/lineal foot) x length of device | Pipes, catch-basins, manholes, valves |
| Inlet structure | ($/structure) or ($/curb cut) | Pipes, catch-basins, manholes, valves | |
| Outlet structure | ($/structure) | Pipes, catch-basins, manholes, valves | |
| Liner | Liner cost ($/square yard) x area of device) | Pipes, catch-basins, manholes, valves | |
| Site Restoration | Filter strip | Sod cost ($/square foot) x filter strip area | Tree protection, soil amendments, seed bed preparation, trails |
| Soil preparation | Topsoil or amendment cost ($/acre) x Area (acre) | Tree protection, soil amendments, seed bed preparation, trails | |
| Seeding | Seeding Cost ($/acre) x Seeded Area (acre) | Tree protection, soil amendments, seed bed preparation, trails | |
| Planting / transplanting | Planting Cost ($/acre) x Planted Area (acre) | Tree protection, soil amendments, seed bed preparation, trails | |
| Annual Operation, Maintenance, and Inspection | Debris removal | Removal Cost ($/acre) x Area (acre) x Frequency | Vegetation maintenance, cleaning of structures |
| Sediment removal | Removal Cost ($/acre) x Area (acre) x Frequency | Vegetation maintenance, cleaning of structures | |
| Weed control | Labor cost ($/hour) x Hours per visit x Frequency | Vegetation maintenance, cleaning of structures | |
| Inspection | Inspection Cost ($) x Inspection Frequency | Vegetation maintenance, cleaning of structures | |
| Mowing | Mowing Cost ($) x Mowing Frequency | Vegetation maintenance, cleaning of structures |
Bioretention device cost estimate worksheet.
Link to this table
| Description | Units | Quantity | Unit Cost | Total Estimated Price |
|---|---|---|---|---|
| Site Preparation | ||||
| Site Formation | ||||
| Structural Components | ||||
| Site Restoration | ||||
| Annual Operation and Maintenance | ||||
| Project Title | ||||
| Owner | ||||
| Location | ||||
| Project Number | ||||
| Date | ||||
| Tree removal - up to 12" diameter | each | $350.00 | $0.00 | |
| Clear and grub brush | square yard | $1.50 | $0.00 | |
| Tree protection - temp. fence | lineal foot | $3.00 | $0.00 | |
| Topsoil - 6" depth, salvage on site | square yard | $4.50 | $0.00 | |
| Excavation - 4' average depth | square yard | $10.00 | $0.00 | |
| Grading | square yard | $1.50 | $0.00 | |
| Hauling off-site | square yard | $5.50 | $0.00 | |
| Underdrain - with pea gravel and geotextile | lineal foot | $30.00 | $0.00 | |
| Inlet structure | each | $1,500.00 | $0.00 | |
| Outlet structure | each | $2,500.00 | $0.00 | |
| Filter strip | square yard | $0.00 | $0.00 | |
| Soil preparation | square yard | $30.00 | $0.00 | |
| Seeding - above outlet elevation | square yard | $0.50 | $0.00 | |
| Planting - below outlet elevation | square yard | $30.00 | $0.00 | |
| Mulch | square yard | $5.00 | $0.00 | |
| Subtotal | $0.00 | |||
| 10% Contingencies | $0.00 | |||
| Subtotal | $0.00 | |||
| Apply MN Location Factor | $0.00 | |||
| TAL CONSTRUCTION COST | $0.00 | |||
| Debris removal | per visit | $50.00 | $0.00 | |
| Weed control | per visit | $50.00 | $0.00 | |
| Sediment removal | per yeart | $500.00 | $0.00 | |
| Replace planting media | square yard | $12.00 | $0.00 | |
| Replace plants | per plant | $5.00 | $0.00 | |
| Mow filter strips | per visit | $50.00 | $0.00 | |
| Erosion repair | square yard | $75.00 | $0.00 | |
| Inspection | per visit | $125.00 | $0.00 | |
| Subtotal | $0.00 | |||
| Apply MN Location Factor | $0.00 | |||
| TOTAL ANNUAL O&M COST | $0.00 | |||
| Minnesota Location Factors | ||||
| Bemidji | 0.963 | |||
| Brainerd | 1.003 | |||
| Detroit Lakes | 0.962 | |||
| Duluth | 0.991 | |||
| Mankato | 0.990 | |||
| Bemidji | 0.963 | |||
| Minneapolis | 1.035 | |||
| Rochester | 0.983 | |||
| St. Paul | 1.000 | |||
| St. Cloud | 1.002 | |||
| Thief River Falls | 1.042 | |||
| Willmar | 0.961 | |||
| Windom | 0.935 | |||
Note: Suggested unit costs are based on RS Means prices for Spring, 2005, then factored into an area basis based on typical design features for Constructed Wetlands BMPs. To be used for preliminary cost estimation
Related pages
- Bioretention terminology
- Overview for bioretention
- Design criteria for bioretention
- Construction specifications for bioretention
- Operation and maintenance of bioretention
- Assessing the performance of bioretention
- Calculating credits for bioretention
- Soil amendments to enhance phosphorus sorption
- Summary of permit requirements for bioretention
- Supporting material for bioretention
- External resources for bioretention
- References for bioretention
- Requirements, recommendations and information for using bioretention with no underdrain BMPs in the MIDS calculator
- Requirements, recommendations and information for using bioretention with an underdrain BMPs in the MIDS calculator