Costs for ponds typically include costs for embankment, riser and spillway structures, outfall protection, vegetative stabilization, excavation, and grading. Additional costs for site preparation can include soil amendments, precision grading, plant materials and creation of occluding layers in coarse-textured soil types if wetlands systems must be created on upland sites due to project constraints. Project costs can be lowered if existing pre-construction site conditions are carefully considered and isolated areas with hydric soils contained within the footprint of the project are utilized as stormwater management facilities.

Additional maintenance costs will be incurred until the establishment of the wetland ecosystem. Invasive plants must be culled and dead plants replaced. The outlet structure may have to be adjusted, based on seasonal observations, to achieve the proper water surface in the pond.

Construction and maintenance costs

The Introduction to stormwater BMPs section outlines a cost estimation method which site planners could use to compare the relative construction and maintenance costs for structural best management practices. These curves 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 the cost estimation worksheet for stormwater ponds, will allow designers to avoid over or under estimation of fixed costs. The table below lists the specific site components that are specific to stormwater ponds. 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.

This table shows Cost components for stormwater ponds
(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 ($/acre) x Affected Area (acre)
Site Formation Excavation / grading 8-ft Depth Excavation Cost ($/acre) x Area (acre) Soil & rock fill material, tunneling
Hauling material offsite Excavation Cost x (% of Material to be hauled away)
Structural Components Inlet structure ($/structure) Pipes, catchbasins, manholes, valves
Outlet structure ($/structure)
Site Restoration Seeding or sodding Seeding Cost ($/acre) x Seeded Area (acre) Tree protection, soil amendments, seed bed preparation, trails
Planting / transplanting Planting Cost ($/acre) x Planted Area (acre)
Annual Operation, Maintenance, and Inspection Debris removal Removal Cost ($/acre) x Area (acre) x Frequency (2 / 1yr) Vegetation maintenance, cleaning of structures
Sediment removal Removal Cost ($/acre) x Area (acre) x Frequency (1 / 5yr)
Gate / valve operation Operation Cost ($) x Operation Frequency (2 / 1 yr)
Inspection Inspection Cost ($) x Inspection Frequency (2 / 1 yr)
Mowing Mowing Cost ($) x Mowing Frequency (4 / 1 yr)
Stormwater pond cost estimate worksheet
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 - 8' depth square yard $10.00 $0.00
Grading square yard $1.50 $0.00
Hauling off-site - 8' depth square yard $10.00 $0.00
'''Structural Components'''
Inlet structure each $2,000.00 $0.00
Overflow structure each $3,500.00 $0.00
'''Site Restoration'''
Sod - above vegetative bench square yard $4.50 $0.00
Soil preparation square yard $5.00 $0.00
Seeding - vegetative bench square yard $0.50 $0.00
Mulch square yard $2.00 $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 $100.00 $0.00
Remove invasive plants per visit $500.00 $0.00
Replant wetland vegetation per plant $10.00 $0.00
Repair erosion square yard $75.00 $0.00
Sediment removal and disposal cubic yard $10.00 $0.00
Mow per visitt $150.00 $0.00
Gate / valve operation per visit $125.00 $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



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This page was last modified on 18 September 2017, at 14:28.

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