StormTank® vs. Alternatives: A Regional Cost Analysis
Underground stormwater detention systems are essential infrastructure for managing runoff, reducing flooding, and protecting water quality in developed areas. However, their installed cost can vary widely depending on regional labor and material pricing. We put together a quick-glance cost comparison to show how three common underground detention options stack up across both higher- and lower-cost regions in the United States.
Cost Breakdown by System and Region
Our comparison models construction on a 5-acre site requiring 75,000 cubic feet (CF) of storage. It assumes specific unit costs for stone, excavation, and labor in each region. Below is a summary of the key findings:
Expensive Regions
Estimated installed system cost per cubic foot:
Arch chamber system: $13.24/CF
Precast module system: $15.08/CF
StormTank Module 25 Series system: $10.98/CF
Estimated total project cost (75,000 CF):
Arch chamber system: $993,000
Precast module system: $1,131,000
StormTank Module 25 Series system: $823,500
In high-cost areas, StormTank systems offer the most competitive installed price per cubic foot and overall project cost. Notably, the stone arch chamber system is nearly two and a half times higher ($4.28/CF vs. $1.84/CF), contributing significantly to the higher total.
Less Expensive Regions
Estimated installed system cost per cubic foot:
Arch chamber system: $9.45/CF
Precast module system: $13.22/CF
StormTank Module 25 Series system: $8.60/CF
Estimated total project cost (75,000 CF):
Arch chamber system: $708,750
Precast module System: $991,500
StormTank Module 25 Series system: $645,000
Even in lower-cost areas, StormTank remains the most economical system both per cubic foot and in total installed cost. Lower labor and excavation rates reduce costs across the board, but the relative differences between systems remain consistent.
Material and Logistics Considerations
Looking closer at what goes into an installation, several practical construction factors stand out as major cost contributors:
Truckloads required: Since StormTank Modules are delivered flat for easy onsite assembly, a 75,000 CF system comes in just 8 truckloads. In contrast, precast systems arrive as full units, pushing the delivery count much higher to about 73 truckloads.
Excavation volumes: Assembly and excavation costs are major contributors to the installed price. StormTank’s lower assembly time helps keep labor expenses down.
Stone backfill costs: StormTank systems also incur less stone cost per cubic foot compared to arch chamber systems. StormTank Modules can reduce the stone backfill required for a project by approximately 40-60% compared to arch chamber systems.
Altogether, these factors show how StormTank Modules can make installations faster, simpler, and more cost-effective compared to other common underground detention options. If you want a deeper look at how StormTank Modules compare specifically to arch chamber systems, check out our blog: Five Reasons to Use StormTank Modules Instead of Arch Products.