Catch basin inlets are used primarily as a way to lead excess stormwater away from areas that are adversely affected by standing water. For example, if a large parking lot doesn’t have the proper way to take rainwater away, customers, clients, or employees may have to wade through a foot or so of water.

An even more dire situation arises if water collects on a major roadway. It doesn’t take much more than an inch or two of water to cause hydroplaning, especially if the vehicle is traveling at a high rate of speed. But inlets aren’t reserved for hard surfaces. If properly sized, inlets can keep public parks or golf courses free of unwanted ponds, otherwise known as breeding grounds for mosquitoes and other pests.

How Many Inlets Are Needed?

This all depends on how big of an area you’d like an inlet (or inlets) to be responsible for. The parking lot of a small convenience market is a much different situation than an interstate highway. Engineering plans may be needed to find out exactly what you need.

The Washington State Department of Transportation requires catch basin inlets to be a certain size for different applications. Type 1 inlets are smaller than Type 2 or Type 3 inlets. The WSDOT type 1 catch basin inlets are two-feet-10 inches by two-feet-six inches.

The catch basin inlets themselves are one-foot-eight inches high, but risers of up to 24 inches can be added to expand the volume of water inlets can handle, up to five feet above the pipe. Risers are just a bit thicker (five inches) than the inlet (four inches) and the frame and grate are another four inches tall.

Of course, the inlets aren’t designed to hold a lot of rainwater but give it somewhere to collect so that any solids can settle into the sump and be vacuumed out as part of routine system maintenance. The WSDOT Type 1 catch basin inlet has 20-inch knockouts on all four sides to accommodate any number of pipes which collect and distribute the water to its final destination.

Advantages of Precast Inlets

When it comes to projects requiring the WSDOT Type 1 catch basin inlets, ease of installation is probably the biggest benefit of using precast products. The pieces are made well before they are needed, so they are ready to go when you are. Whether the job calls for two or 20 inlets, we’ll get them to you on time and ready for installation.

Because these specific inlets are used statewide, they’re in pretty high demand. At Columbia Precast, we make some products even if they haven’t been ordered yet. This way, we can offer quick turnaround times on standard products, such as a type 1 inlet, standard manhole, or vault structures.

Finally, precast inlets are created in a controlled environment, meaning they can be produced no matter the time of year. With pour-in-place concrete, you have to wait until conditions are relatively decent. This could push back due dates and deadlines. No such worries with precast pieces.

Need a few WSDOT Type 1 precast inlets for an upcoming public or private project? Contact us for an estimate and see how we can help. Does your plan call for environmental considerations? Columbia Precast Products has you covered as the first buried infrastructure facility to earn SMaRT certification in the U.S., meaning the product and our partners have been vetted as being friendly to the environment.

Give us a call. We look forward to hearing from you.

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W.S.D.O.T. - Type 1 Precast Inlet