Trench Drains

Photo of precast concrete trench drain.

Commercial and residential properties depend on trench drains (sometimes called channel drains) to redirect excess storm water and waste water runoff from creating unsafe surface-pooling on driveways and parking lots.

Technical drawing of precast trench drain
Click above trench drain drawing to download technical drawing PDF.

The Purpose of a Trench Drain

The purpose of a trench drain is to collect excess water from a driveway or parking lot, and direct it to a small-scale catch basin. Further water treatment depends on whether the runoff is contaminated or non-contaminated. For example, commercial garages, gas station parking lots and car washes that clean vehicles’ oily undercarriages all rely on trench drains to intercept and redirect water, to prevent runoff of oil, gas, or other liquids to the surrounding environment

How a Trench Drain Works

Trench drains are designed to direct non-contaminated runoff to a dry well/leaching chamber that disperses the water. Contaminated runoff is first directed to an oil/water separator before the water is transmitted to a dry well or city drain/catch basin.

System Benefits

When accurately specified and properly installed, these systems:

  • Prevent unsafe buildup of water and other liquids in parking lots and driveways
  • Keep driving surfaces safe and functional for people and their vehicles
  • Protect the surrounding environment

Design and Types

The design of the system depends on calculations and factors such as the number of catch basins required; amount of rainfall anticipated per catch basin; anticipated weight loading, and more.

Precast Concrete Trench Drains – are considered the strongest, most cost-effective, low-maintenance solution for our harsh northeast climate. See below for sizes and benefits of precast concrete drain systems manufactured and installed by A.J. Foss.

Photo of precast concrete trench drain side view.

Plastic Channel Drains – can only be used for residential driveways since they are not engineered for vehicular weight – unless they’re encased in concrete – so the preferred solution is to install a precast concrete system.

Other disadvantages of plastic include:

  • Plastic is compromised by the sun’s UV rays
  • Plastic drains are smaller than precast; typically only up to 5-in. x 5-in. height and width, which is much less volume than precast.
  • Plastic requires the extra prep work of concrete encasement

Benefits of Precast Concrete Trench Drains Manufactured by A.J. Foss

Photo of the top view of our precast concrete trench drain.

  • Engineered for H-20 vehicular loading
  • Available in a variety of larger sizes
  • Are ready to install without the extra prep work that plastic encasement requires
  • All open sections are chamfered, to allow for a smooth transition after mortaring the joints
  • Have no unsightly motor joints that enable the build-up of leaves and silt
  • Are not as affected by the sun’s UV rays as plastic
  • Prevent damage to snowplows and property when rails and grates are properly installed
  • The design enables better protection of the concrete, because it allows for pavement to be placed over the concrete perimeter, up to the rails that hold the grates into place. This means that any damage to the concrete will occur below-grade, allowing for repair without removing the pavement and replacing the whole concrete trench. Otherwise, if grates are installed flush with the top of the concrete, it’s not possible to pave the concrete perimeter; thus the exposed concrete is vulnerable to salt destruction over time, as well as damage from snow plows hitting the slightly-protruding grate above the pavement.

Available Sizes

  • 20-in. tall, 24-in. wide
  • Available in 2, 3, 4 and 6 ft. lengths
  • 10-in top opening; works with either 12 or 14-in. wide grates
  • 5-in wide top shelf allows for either iron or cast iron railings

Trench Drains PDF Files