Cost considerations for dry swale (grass swale)
Information: The following table is generally applicable to filtration BMPs and not specifically to swales. Some items may not be applicable.
Cost estimates that site planners can use to compare the relative construction and maintenance costs for structural best management practices are excellent for purposes of comparison. However, it is recommended that construction and maintenance budgets should be based on site specific information. Utilizing the table below and cost estimation worksheets will allow designers to more accurately estimate the cost of a filtration BMP.
Cost components for filtration practices.
Link to this table
| Implementation Stage | Primary Cost Components | Basic Cost Estimate | Other Considerations |
|---|---|---|---|
| Site Preparation | Tree & plant protection | Protection Cost ($/acre) x Affected Area (acre) | Removal of existing structures, topsoil removal and stockpiling |
| Topsoil salvage | Salvage cost ($/acre) x Affected Area (acre) | ||
| Clearing & grubbing | Clearing Cost ($/acre) x Affected Area (acre) | ||
| Site Formation | Excavation / grading | X-ft Depth Excavation Cost ($/acre) x Area (acre) | Soil & rock fill Hauling material material, tunneling |
| Hauling material offsite | Excavation Cost x (% of Material to be hauled away) | ||
| Structural Components | Under-drains | Under-drain cost ($/lineal foot) x length of device | Pipes, catchbasins, manholes, valves, vaults |
| Vault structure (for media filters) | ($/structure) | ||
| Media (for media filters) | Media cost ($/cubic yard) X filter volume (cubic yard) | ||
| Inlet structure (for vegetative filters | ($/structure) | ||
| Outlet structure (for vegetative filters) | ($/structure) | ||
| Site Restoration | Filter strip | Sod cost ($/square foot) x filter strip area | Tree protection, soil amendments, seed bed preparation, trails |
| Soil preparation | Topsoil or amendment cost ($/acre) x Area (acre) | ||
| Seeding | Seeding Cost ($/acre) x Seeded Area (acre) | ||
| Planting / transplanting | Planting Cost ($/acre) x Planted Area (acre) | ||
| Annual Operation, Maintenance, and Inspection | Debris removal | Removal Cost ($/acre) x Area (acre) x Frequency (2x / 1yr) | Vegetation maintenance, cleaning of structures |
| Sediment removal | Removal Cost ($/acre) x Area (acre) x Frequency (1x / 5yr) | ||
| Gate / valve operation | Operation Cost ($) x Operation Frequency (2x / 1 yr) | ||
| Inspection | Inspection Cost ($) x Inspection Frequency (6x / 1 yr) | ||
| Mowing (for some vegetative filters) | Mowing Cost ($) x Mowing Frequency (4x / 1 yr) |