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Underground Stormwater Detention and Filtration Systems  

Subsurface stormwater management systems are designed to maximize land space while improving stormwater detention and filtration. Just like detention and retention ponds, underground stormwater detention systems capture and store stormwater, filter runoff and discharge treated water at controlled rates.

There are several different underground stormwater systems. These systems vary by material, design, configuration and performance metrics.

Chamber Stormwater Systems

Stormwater chamber systems are designed for below surface stormwater storage for commercial, municipal and residential applications. Polypropylene chamber systems allow you to maximize holding capacity without sacrificing land space. These detention and filtration systems are ideal for paved surfaces but can also be designed into green spaces and multi-use areas.


  • Parking lots
  • Roadways
  • Heavy earth loads
  • Green space
  • Residential areas
  • Multi-use areas

Chamber System Benefits

  • Saves land space
  • Long term reliability
  • Large capacity storage in small footprints
  • Alternative to metal pipe
  • More cost effective than concrete pipe
  • Applicable for LID (Low Impact Development) and Green Infrastructure

Chamber System Material

Chamber systems are manufactured from polypropylene, resulting in a strong but lightweight system with incredible strength, hardness, stability and abrasion resistance. Each half-moon section is injection molded for a precise and uniform system.

Improve Filtration + Maintenance

Enhance a chamber system’s performance and improve maintenance with a filtration row. A filtration row is typically wrapped in a geotextile fabric and backfilled with stone. This row is located near a man hole or drain basin so that it can be easily accessed for inspection, testing and maintenance. The filtration row is designed to capture the first flush of rainfall. As runoff enters the chamber through the filtration row, it passes through the geotextile fabric and fills the pipe before passing to the other stormwater chambers.

Corrugated Metal Drainage Pipe

Large Diameter Pipe Systems

Polypropylene (HDPE), corrugated metal (CMP), concrete and steel reinforced concrete pipe (SRPE) are all used to create underground stormwater detention systems. When large diameter pipe systems are complimented with a filtration device, these systems can outperform chamber systems.


  • Parking lots
  • Neighborhoods
  • Green spaces

System Benefits

  • Saves land space
  • Large volume of cubic storage
  • Varying material
  • Product availability

Filtration devices

Adding a filtration device to a large diameter pipe system maximizes the system’s performance capabilities. Filtration devices filter stormwater runoff and remove nutrients while the large diameter HDPE, CMP, SRPE or concrete pipe stores stormwater.

Sand Filtration Stormwater System

Corrugated Metal Sand Filter System

The Corrugated Metal Sand Filter System is a below ground version of a surface-level sand filter. This subsurface corrugated metal pipe system captures stormwater, filters runoff and discharges treated water to meet EPA standards.


  • Neighborhoods
  • Green spaces
  • Parking Lots

System Benefits

  • Lightweight
  • Durable
  • Meets EPA standards
  • Multiple configurations available to meet design requirements

CMP Sand Filter Stormwater System

The subsurface Sand Filter System is manufactured from lightweight and durable corrugated metal pipe. CMP is available in multiple coatings to meet site standards. The below ground vault is offered in circular or arch shape metal pipes.

Sand Filter Design

The Corrugated Metal Sand Filter System is comprised of three chambers: a sediment chamber, a sand bed filter and a clear well.

Sediment Chamber

The sediment chamber captures the first flush of storm water, filters sediment and provides temporary storage.

Sand Bed Filter

The sediment chamber and sand bed filter are connected by a wall that prevents oil and trash from compromising the sand filter. The filter bed is 12” – 24” deep and can be enhanced with a gravel or geotextile barrier.

Clear Well

Underdrain discharges treated water from the sand filter to the clear well.

Concrete Stormwater Systems

Concrete Stormwater Systems are underground detention and infiltration systems that offer superior strength, durability and load bearing capacity. Concrete Systems are typically installed below parking decks but are also designed to for underground detention below buildings and green space. Concrete Stormwater Systems require less stone fill than metal and plastic systems which results in a cost-savings to the contractor. Many Concrete Systems do require a crane for installation.


  • Parking decks
  • Parking lots
  • Buildings
  • Green spaces

System Benefits

  • Superior Strength and durability
  • Lightweight despite material strength
  • High load rating
  • Limited stone fill
  • Easy inspection and maintenance

Concrete System Design Details

There are several different types of Concrete Stormwater Systems including single chamber pre-cast modular systems, single barrel systems and multi-barrel systems.

Single and multi-barrel systems have internal baffle walls and watertight seals that trap oil and trash. This configuration has the option to add a sand filter to treat stormwater runoff.

Both modular and barrel systems can be designed in multiple configurations, with varying sizes and volumes of backfill.  

Modular stormwater system

Modular Systems

Modular Stormwater Systems use void space to maximize storage capacity in tight-space applications. Modular Systems are designed for retention/detention, stormwater infiltration and rainwater harvesting. This below ground stormwater system regulates the flow of stormwater and temporarily stores large volumes of stormwater before it discharges into the soil at a controlled rate. 


  • Parking lots
  • Residential homes
  • Athletic fields
  • Commercial developments

System Benefits

  • Saves land space while maximizing stormwater storage
  • Load ratings up to HS-25
  • Multiple configurations
  • Easy to install
  • Ships palletized

Modular Stormwater System Design

Polypropylene Modular Systems utilize a high void space (up to 97%) to increase the stormwater storage capacity. These systems have an open design which means there are no internal walls. Instead, there are columns and top and bottom panels. The panels distribute weight evenly into the columns, enabling the system to bear heavy loads (up to HS-25 load rating).

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