Cost-benefit considerations for filtration

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 for either bioretention or surface sand filter 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)

Surface sand filter cost estimate worksheet.
Link to this table

Project Title
Owner
Location
Project Number
Date
Description	Units	Quantity	Unit Cost	Total Estimated Price
Site Preparation
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
Site Formation
Excavation - 6' depth	square yard		$8.00	$0.00
Grading	square yard		$1.50	$0.00
Hauling off-site - 6' depth	square yard		$10.00	$0.00
Structural Components
Underdrain - with pea gravel and geotextile	lineal foot		$400.00	$0.00
Inlet structure	each		$1,500.00	$0.00
Sand filter media - 18" depth	square yard		$15.00	$0.00
Outlet structure	each		$3,000.00	$0.00
Site Restoration
Sod filter strip	lineal foot		$1.50	$0.00
Soil preparation	square yard		$5.00	$0.00
Seeding - above outlet elevation	square yard		$0.50	$0.00
Subtotal				$0.00
10% Contingencies				$0.00
Subtotal				$0.00
Apply MN Location Factor				$0.00
TAL CONSTRUCTION COST				$0.00
Annual Operation and Maintenance
Debris removal	per visit		$50.00	$0.00
Mowing	per visit		$150.00	$0.00
Sediment removal	per yeart		$500.00	$0.00
Gate / valve operation	per visiit		$125.00	$0.00
Erosion repair	square yard		$75.00	$0.00
Inspection	pper visitt		$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

• Overview for filtration
• Types of filtration
• Design criteria for filtration
• Construction specifications for filtration
• Assessing the performance of swales
• Assessing the performance of sand (media) filters
• Operation and maintenance of filtration
• Calculating credits for sand filter
• Calculating credits for swale
• Cost-benefit considerations for filtration
• References for filtration