Designing Better Catch Basins

When you go the extra mile to build a catch basin from scratch, you’ll want to address the specific shortcomings of most precast models. Sticking to precast concrete basins can save both time and money. Yet in exchange for these savings, you’ll add other complications to your storm water drainage system that may not become apparent for years. Committing to better catch basins will pay off for the lifespan of the drainage system, even during upgrades and repairs.

Maintenance Difficulties

First, precast catch basins are well known for their difficulty to clean out and empty. Many of these concrete basins are so small that they’re hard to reach into, especially if an equally small grate is installed on top. Larger concrete basins usually feature sharp corners that trap dirt and debris even from the most thorough maintenance workers. Installing a smoother layer of flexible RPE liner in a custom basin creates a surface that is easier to clean and minimizes maintenance work.

Under sizing or Oversizing

Manufacturers can only produce so many different models of a single product. This means that you’re stuck choosing between sizes of catch basins that may vary as much as 500 gallons between options. Getting just the right size of basin minimizes excavation costs and speeds up installation. Undersized catch basins also create serious flooding and backflow risks. Only a custom fabricated basin is built just to the specifications of the engineering designs. If your hydrological engineer calls for a 2,000 gallon catch basin and you can only find a 1,000 or 3,000 gallon precast unit, onsite construction is often the only choice.

Covered Grates

A flush grate, that sits at the lowest point of a parking lot or other paved area, seems like the perfect way to add drainage. For a while, it will work smoothly in draining away water that would otherwise stand on the surface. But as the water flows to the grate, it also carries along plenty of debris. Anything too large or light to flow through the grate and into the basin will simply sit on top. This is by design, since it’s much easier to remove debris from the grate than from the basin. But if no one plans on cleaning the grate, the basin will quickly fail to function. Choosing a grate that lets in the majority of debris, common to the area, reduces the amount of cleaning necessary to keep it working properly.

Clogged Outflow Pipes

One of the most common reasons that catch basins fail is due to clogs in the outflow pipe that release the runoff to the rest of the drainage system. This is primarily down to the placement of the pipe in relation to the usual level of water. A low pipe will suck in debris that settles to the bottom and let water run off too quickly to settle out any trash. On the other end, high pipes take too long to let water escape and only flow when there’s a sudden surge that washes fat and floating debris into the pipe. Proper estimation of the usual level of water in the basin will allow for accurate placement that minimizes drainage pipe clogs as much as possible.

Direct Release

Shallow and undersized catch basins don’t function in the same way deep sump designs do. Shallow basins do little to separate out waste products like trash and oil from the rest of the water. This means that mixed and raw run off goes out through the outflow pipe and into the next part of the system. Some basins are designed to operate this way, but it’s also an accidental feature of many models. If you’ve designed the system around the trash separating power of a sump, it’ll function poorly when the catch basins aren’t sized to actually produce the desired effect.

Lack of Marking

It’s all too easy for the public to mistake a storm water drain or catch basin for a public dumping point. These basins are designed to handle the small amounts of oil, dirt, and other substances that get carried along by the running water. If someone brings a gallon of paint or a bag of tissues to the drain and dumps the waste in, the basin will clog and overflow during the next rain fall. Even if the basin manages not to overflow, the direct application of trash will still damage some other part of the system. Mark as many drains and basins as possible so the public knows not to use them as dumping stations for anything, including large amounts of pure water.

Mosquito Infestation

Catch basins are particularly prone to hosting mosquito eggs and larvae because they’re constantly holding some amount of water. Your average grates and covers will allow mosquitoes to easily fly down to the water’s surface for depositing their eggs. Accessories, like mosquito cones and filters, allow water and trash to enter the basin while the insects stay out. This can reduce pest pressure significantly in the areas around the basins without the need to periodically add floats, oils, or pesticides to the water on a regular basis.

Make the most of each catch basin you add to your storm water drainage system with a custom design and quality liner that addresses real world challenges. When you’re ready to order the multi-layered RPE liner you need for your storm water project, reach out to us here at BTL Liners.

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