Installing a catch basin can solve many drainage problems whether in your yard or in a commercial parking lot. Many people have problems with standing water on their properties due to flat terrain that does not drain well or to soils that simply will not absorb the surface water. Low areas in a garden or lawn can ruin the lawn or garden planting soils by capturing rain water and creating a ponding issue. Soggy lawns cannot be mown and wet garden soil turns to mud and can kill your plants. A simple remedy can be the installation of a catch basin to contain or drain way all the excess water. If you can install a drainage pipe to your catch basin that can empty into a drainage ditch elsewhere, that is ideal. If not, there are other solutions to be had.
Catch basins come in all different sizes and types. Concrete, plastic and PVC materials are quite common. If you need a larger catch basin but can not access the area with heavy equipment to carry and set it, you can construct one yourself out of masonry units. Depending on how severe the ponding issue is, that will determine the size catch basin you need. If it occurs only occasionally and you can install a drainage outlet pipe, a small two foot diameter PVC basin may suffice. Easy to hand carry as they are lightweight, and easy to install, they can be driven over by a lawn tractor with no problem. An outlet pipe will help quickly drain away the water form this small basin. If you have a larger water problem, a precast concrete basin may be in order.
Precast concrete basins are extremely heavy and require some type of machinery to move and set in place. You will need to excavate a fairly large hole so a mid sized backhoe can both dig the hole and pick up and set the basin. The smallest catch basin I have seen is twenty-four inches square and thirty inches deep. Not really worth all the effort as a larger three foot square and three feet deep basin will accept a great deal more water if no outlet pipe is possible. You may order your non-outlet basin with a drainage hole cast in the bottom so the basin can accept the rainwater during a storm and then slowly return the water to the ground through the bottom drain hoe. A twenty-four inch diameter grate will allow the fastest passage of water into the basin and are available from most precast suppliers. They will last your lifetime. In a driveway or parking lot, you will need to order what is designated as an H20 loading basin and lid. These type are capable of carrying an automobiles weight.
Installing a basin is a fairly straight forward process. If you are not installing an outlet pipe, then you only care that the finished basin and lid are slightly below the surrounding grade or paved areas. This setup when back filled, will allow the water to find the basin as everything slopes to the basin. If you are installing an outlet pipe, you have to be sure you point the outlet hole in the basin in the correct direction when setting it.
You will want to measure the height of the basin plus the lid plus whatever thickness of stone you wish to place below the basin. Six inches of stone is a minimum to provide a good base for a heavy catch basin. If you are using a bottom drain type basin, a two foot thickness of stone is much better. This will allow additional “storage” space for water until the ground has time to absorb it all. With this total overall measurement in hand you may excavate the hole. You want the top of the lid to ideally be about two inches below the surrounding area to promote drainage.
Take great care when working around a precast basin. Never, ever get under the basin for any reason. If, when you set it and the gravel needs to be re-raked, lift the basin completely out of the hole and to the side before you enter the hole. Chains and cables break or snap, hydraulic lift cylinders on machines fail and any one of these would cause you to be crushed to death. Take no chances. Lift it in and out five times if necessary to make the work area safe.
Once your gravel is level and the basin is set, check the basin’s levelness in two directions with a good four foot hand level. Once done, set your frame and lid in place and cover it with plywood to prevent any earth from falling into the catch basin when you back fill around it. If you can compact the earth as you go, you will get far less settlement later on.
After a good rain, regrade the back fill around the basin to make a nice even slope to the new catch basin lid.
Pete Ackerson