Concrete Drain Systems,
Trench and Channel Drains

Catch basins and point drains
If you have sufficient contour to the site or you can’t use a channel or trench drain, a catch basin or point drain may be the drainage system you need to use. Both of these systems require the concrete to slope to a central point for water collection, and plumbing is necessary under the concrete to drain water away from the site.

A point or area drain is set up much like a shower drain, with a small grate in the center. A single drain pipe leads water away, though the pipe may have several point drains located along its run.

A catch basin is a catchment receptacle with outlet ports set into the ground at the base of a basin. Pipes are attached to the outlet ports to channel water away from the site.

These are not the easiest drains to install. Pickering points out they require “complex four-way grades to work effectively.” Also, while product costs are usually low, “The additional cost of extensive pipes and excavation costs are often ‘forgotten,’” she adds.

Choosing a grate
Many factors are involved in choosing a grate — not just cost.

Load rating is a critical factor, says Tyler. “The grating needs to support the application.”

When evaluating load rating, Tyler advises that you consider the weight and size of vehicles, the speed of approach of the vehicles, and if the vehicles have pneumatic or hard tires. A grate you integrate with a walkway or driveway may require only a “light traffic rating.” On the other hand, the hard tires of forklifts are tough abuse for a grate, requiring a heavier “H-20 load rating.”

If you’re not sure about a grate’s load rating, talk to the manufacturer about your project’s specifics. Tyler explains, “I would rather have the call before the job, rather than after an improperly installed grate breaks.”

Durability is also important. Pickering asks, “Are the trench and grate materials resistant to the liquids/chemicals being drained?” Grates are made from a wide range of materials, including plastic, brass, cast iron, ductile iron and stainless steel. The load rating also may be dependent on the durability of the grate material.

Aesthetics usually come in to play after load and durability factors are considered. If cost is an issue initially, remember that grates can often be changed out later and upgraded to a more desired material, finish or design. Other user issues may involve safety — including Americans with Disabilities Act requirements — and security issues, such as how easy is it to remove the grate.

Remember the key elements
Engineers and architects usually do the homework up front and specify the necessary drainage recommendations for commercial and industrial projects. Design-build and residential contractors may not have that benefit. But making smart decisions about drainage systems is not hard if you keep in mind a few key factors.

In choosing a drain system for a particular application, first determine the hydraulic performance required — this will tell you the size drain you need. Then look at the site itself. Space limitations and sloping issues will drive the selection of a drain type. As Bud Stegmeier, co-owner of Stegmeier Corp. in Henderson, Nev., points out, if you use multiple point drains, you’ll have to deal with the ups and downs of multiple bowls, whereas “with a trench drain you’ll still have the slope [and] it won’t be level, but it will be flat.”

In selecting a grate, be sure to consider loading factors, durability issues and user requirements.

Finally, don’t forget that drainage systems need maintenance and cleaning. With trench drains, you can access the entire system through the grate and debris can be easily flushed to the catch basin for removal or shoveled clean, reports Pickering. Maintenance on catch basin or point drain systems is trickier because pipes are buried; blockages can be difficult to locate and remove.

When choosing among the many products available in the marketplace, Steve Born, operations manager of MultiDrain Systems Inc. of Erlanger, Ky., recommends that contractors look at ease of installation, labor costs, the system cost and the time it takes to install. Also helpful is making sure the manufacturer has the technical staff available to answer any questions you may have — before you get started and as your project progresses.