Green Buffalo.
Constructed Wetland System Cost Analysis
Below we have a cost analysis, estimating the price to construct 4-acres of wetlands systems from Waugh Allen Pkwy to Houston Downtown.
number of wetland (acre):4
Wetland seed mixes (per pound):12
Sheet pile plate:4
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Upfront initial Cost of items Year cost Average Price (Wetland acre) Average price per drainage acre
Wetland Design cost 1 $6,000.00 $40.00
Constructed Basin 1 $0.00 $0.00
Wetland Plants and planting 1 $1,200.00 $12.00
Wetland buffer seed 1 $524.00 $131.00
Seeding buffer 1 $160.00 $40.00
Weir Plate 1 $120.00 $4.00
Control Structure 1 $5,200.00 $1,300.00 .
Total Cost: $13,204.00 $1,527.00
Long- term management Costs
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Time to manage (mowing buffer) 3 - n years $12.40 $3.10
Replace control Structure gate Every 8 yrs $60.00 $15.00
Land rent for Wetland acre 0 - n years $1,000.00 $250.00
Land rent for buffer of wetlands 1 - n years $35.00 $8.75
Constructed structure/WR ~ 40 $3,740.00 $935.00
Total Cost: $4,847.40 $1,211.85
Figure 1: Constructed Wetland Cost
Important Notes Regarding the Cost of each item
Wetland Design cost
Assuming 10 hours at $150/hr for a 1-acre wetland. Designing 4 wetland.
Constructed Basin
Building ponds is about 15 hours at approximately $50/hr for 1-acre wetland. Since we are putting the wetlands in the bayou. There is no need to build the ponds.
Wetland Plants and planting
For shallow wetland systems, 100-150 plants per acre will help ensure sufficient establishment in open water areas. A wetland seed mix that covers wetland banks about 1/3 of the basin area is also advisable. Wetland seed mixes range $75 to $100 per pound of seed. We are averaging $100 per pound of seed and we need 12 pounds which is 3 pounds for each acre.
Wetland buffer seed
Average Regional seed costs: $131.00 per acre for 3.5 buffer seed area.
Seeding buffer (broadcoast with tractor)
Sedding buffer is about $40 for acre. We are sedding buffer all 4 acres.
Weir Plate
Assuming $30 per sq. ft for 200 sq. sheet pile plate, for 1 ac site. We have 4 ac sites.
Control Structure
One control structure ranging from 5 ft deep, 18-inch pipe ($1,300 per ac.) to 10 ft deep, 24-inch pipe ($2,900 per ac) for 10 ac wetland site. We are using the 5 ft deep 18-inch pipe for the 4-acre wetland. Since the bayou is not that deep.
Time to manage (mowing buffer)
About $3.10 for each buffer. Every 3 to 6 years to mowing the buffer for all 4 acres of wetlands.
Replace control Structure gate
Is $15 per acre every 8 years. We have 4 acres.
Land rent for Wetland acre
State wide average land rent is approximately $250 per acre. Note: this would be an annual cost reference, at this value of $250/ac/year over a 50-year period (the expected lifespan of the wetland) @ 4% would be about total cost of $38,000 for one wetland.
Land rent for buffer per ac of wetlands
Is about (3.5% of 1 acre of wetland) and If the State-wide average land rent is approximately $250 per acre. We are looking at a cost of $8.75 for each wetland.
Constructed structure and weir replacement
Is about $935 every 40 years for 1-acre wetland.