Open-top slotted drain (OTSD) pipe is a practical and cost effective combination of catch basin and drain pipe for the collection of runoff. The open-top slotted drain pipe is specifically designed to handle sheet flows across paved surfaces, in locations such as:

• Parking garages and lots
• Loading ramps
• Aircraft aprons and taxiways
• Athletic fields
• Curb inlets
• Surfaces with pedestrian or bicycle traffic
• Factory or plant floors

The open-top slotted drain pipe is fabricated by cutting a continuous longitudinal opening into the top of corrugated steel pipe, and welding a steel slot, of the required depth, to the edges of the opening. The open-top slotted drain pipe is placed at the site with the top of the steel slot level with the paved surface, to enable water flowing across the surface toward the open-top slotted drain pipe to flow through the slot into the pipe. The paved surface must be sloped toward the slot on the top of the open-top slotted drain pipe, and the open-top slotted drain pipe must be at the low point of the sloped surface.

Open-top slotted drain pipe offers several advantages over a typical checkerboard paving pattern, with its array of catch basins and connecting pipe.

• Reduces the number of, or eliminates catch basins
• Reduces the length of pipe required to drain the site
• Simplifies the paving layout
• Reduces maintenance difficulty

The specifications developed by these organizations are listed below.

Open-top slotted drain pipe is available in pipe diameters from 12" through 36", and in either 16 or 14 gage. The standard pipe length is 20 feet, but other lengths can be made to order. Available pipe materials are galvanized and Aluminized Steel Type 2. Pipe fittings are available to accommodate changes in pipe alignment, but the fittings are not provided with slots.

The slot atop the pipe has a standard inside width of 1 ¾" and the length of the slot is nominally 19' - 2". The slot stops 5" short of each pipe end in order to allow for installation of standard band couplers, used to connect pipe sections. The standard slot depths are 2 ½" and 6", but open-top slotted drain pipe can be fabricated with other uniform depths. If variable depth slots are required to match jobsite conditions, they can be fabricated and shipped to the site with the required slope built into the open-top slotted drain pipe assembly. Spacers inside the slots (spaced at 6" c/c) keep the slots open during installation and use, and also keep debris from entering the pipe. These spacers are typically perpendicular to the sides of the slots but can be placed at an angle of 30 degrees with the sides of the slot.