Designed to keep stormwater, other precipitation, and liquids in general from gathering in any one spot, a combination inlet features either a grate opening, curb cut openings, or a combination of the two. These combination inlets are placed when low-grade situations have been created during the construction of the water management system.

Leaves, garbage, and a host of other debris can cause clogging factors within the system. Once the system becomes clogged, the water from the gutter line begins to accumulate at sag locations. At a major intersection, this can be uncomfortable for pedestrians and downright scary for drivers.

Two Inlet Types

Curb and grate inlets are designed to capture water and take it away from a road or other hardscape. A grate inlet is in a low spot on the street itself, next to a curb so that water will flow into it.. Most roads are built with a gradual hump, the middle of which is in the middle of the street.

This forces water to one side or the other, which creates the gutter flow, which is then sent down to the grate inlet. As you might expect, the grate inlet has a grate at the top (see image below). There could be city, county, or state requirements on the size of the grate openings.

If a curb inlet is used, a cover in the sidewalk is used for access. A curb opening length is typically two or three feet wide with trash bars placed every inch or so. This keeps larger pieces of debris out of the inlet while still allowing stormwater to enter.

The size of the inlet depends on the local jurisdictions. In Clark County, WA, the inlets are 1-foot-6-inches in depth and three feet wide. However, no matter the specifications, Columbia Precast Products will deliver what you need when you need it.

Advantages of Precast Concrete

That’s the main benefit of using precast concrete for these projects. Once the excavation is complete, combination inlets are ready to be installed and then backfilled. As a general contractor, this means your project stays on schedule, which means you’ll stay in the good graces of the public agency that hired you.

With the push to use green products in public projects, Columbia Precast Products was the first buried infrastructure plant in the U.S. to earn SMaRT Certification. This means our combination inlets should satisfy all environmental requirements. Our product, process, and even how we choose our partners are all sustainable.

Even in private use, you’ll be getting a combination inlet that is designed to last a century. This means fewer replacements, less maintenance, and peace of mind. Contact Columbia Precast Products for your upcoming job – we’ll be happy to talk about how we can help.

Type 1 Catch Basin – Optional Curb Inlets

Click to download as a PDF.