Catch Basins and Manholes

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Catch basins and manholes each use precast structures, but different job purposes require their service.

The A.J. Foss team services area waste water and stormwater systems by manufacturing a complete line of custom catch basins and manholes.

A typical catch basin plumbing setup includes a slotted or perforated metal grate set on the top of it at ground level to allow water to enter into the structure.

On a manhole, the top is closed so you would use a solid cover on top of it, either 24" or 30" in diameter.

Catch Basins

Catch basin drains are a type of water drainage inlet designed to collect excess rain and storm water runoff from roofs, sidewalks, parking lots, and paved streets.

A catch basin is a precast concrete structure with a sump* that allows solids, trash and debris to settle out to the bottom of the basin.  Outlet pipes located above the basin-bottom are designed to allow water to flow out of the structure. During a heavy rain storm, a catch basin and sump can become overwhelmed to the point of not enabling trash and debris to settle out. The high rate of water flow can cause trash and debris to rapidly rise toward the outlet pipe.  Since pipes are not typically fitted with hoods or trash-screens, any material that becomes suspended in the water near an outlet pipe can exit the structure through pipes in the high rate of discharge flow.

Our team recommends using a hooded outlet cover that converts any sumped stormwater structure to reduce pollutants such as floatables and trash, as well as free oils, and sediment.

*Sump is the distance from the bottom of the structure to the bottom of the outlet pipe. A catch basin sump depth is typically 3 feet, and a manhole sump depth is typically 6 inches.

Advantages of Catch Basins:

  • Catch Basins & Manholes are H-20 Loading
  • Rubber plumbing boots can be used
  • They ensure watertight pipe-to-structure connections and quicken pipes installation. (No need to wait for the hydraulic cement to dry before back-filling the structure)
  • Crafted with precast, high strength concrete
  • Easy and quick for plumbers and others to install, with minimal plumbing connections
  • Various sizes available, to address job design parameters
  • A drop inlet catch basin is ready-for-installation. (While a typical catch basin job is made to order, we stock blank pieces for which we use our advanced coring machine to core the required holes at the appropriate heights and elevations.)

Catch Basin Component Sizes

  • Flat top cover sizes range from 1 to 4 feet
  • Riser sizes range from 1 to 4 feet
  • Base sizes range from 2 to 5.5 feet

4' Catch Basin Components Diagram

5' Catch Basin Components Diagram

Catch basins are typically custom-manufactured from engineered drawings due to their exacting requirements. The A.J. Foss team manufactures 4-ft. and 5-ft. diameter precast concrete catch basins that are custom made per each project’s requirements.

Drop Inlets (which are a type of catch basin) are ideal for any job that requires a pre-fabricated, ready-to-use structure that includes knockouts for on-site adjustments.


A manhole does not typically include a sump because it does not have an open top like a catch basin has. Manholes are used in a closed system, while catch basins have openings at the top to allow water to collect in them. A.J. Foss manufactures 4-ft. & 5-ft. diameter manholes that are custom-made per each project’s requirements.

Manhole Uses and Structures

Sanitary sewer systems and storm drain systems use precast circular concrete manholes to provide access, observation and junctions.

Precast concrete manholes are appropriate for:

  • Pump stations
  • Wet wells
  • Stormwater management structures

Loading Requirements

All A.J. Foss-produced manholes and vertical structures are designed and manufactured for H-20 loading.

Manhole sizes

Precast circular manholes are 4-ft or 5-ft in diameter

Uses for precast circular manholes:
  • Access for system maintenance
  • Changes in shape, size, or direction of pipe
  • Observation points
  • Multiple pipe junctions

Uses for precast circular catch basins:

  • Stormwater management
  • Pond overflow structures

Available features of precast circular manholes and catch basins:

Most items are manufactured without inverts; however, with our state of the art stationary coring machine we can core and ship your order with quick turnaround time.

Contact us to discuss your projects throughout New Hampshire, Maine and Northern Massachusetts that require wastewater and stormwater products, and discover the A.J. Foss difference for yourself.

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