Gate City Foundation Drainage — Installing a French drain and catch basin system around a garage structure
In the first video of a two-part series, Shawn (Gate City Foundation Drainage @ YouTube; Gate City Foundation Drainage) is helping to install a French drain and catch basin system at his friend’s rural property. Rainwater coming down off of some sloped ground at a neighboring property has been causing flooding around a garage structure.
Some dirt behind the garage is excavated to create an area for the French drain to be laid, and some more excavation is performed under a canopy along one side of the structure to allow a square plastic catch basin to be placed in the ground.
A layer of gravel is laid in the French drain pit, and two runs of drainage pipe are then placed on top of that. The two runs are then joined into one pipe that will lead to the catch basin at the side of the garage, near the canopy.
To drain the catch basin, some eight-inch-diameter piping is used. The pipe is laid out on the ground next to the garage to figure out the eventual path, and spray-painted lines along the edges of the pipe segments are used to mark on the ground where to dig. When the alignment is finalized, a trench is excavated for the pipes.
A hole is drilled into the corner of the plastic catch basin to allow the pipe from the French drain to be connected. The first segment of the larger-diameter pipe draining the catch basin is also connected to the catch basin.
Another layer of gravel is placed on top of the pipes of the French drain.
Shawn mentions a number of times throughout the video that this drainage system is being designed by his friend, and the approach being taken differs from what Shawn would typically do.
Shawn returns in the second part to complete the drain system installation.
A small trench is dug by hand to add a pipe that will be used to connect an eventual downspout for the canopy over to the catch basin that was installed earlier. A hole is drilled into the side of the catch basin to accept this pipe, and the pipe is laid within the trench. The ninety-degree fitting used to accept the downspout is then spray-painted black.
More trenching is done for the pipes that will run from the catch basin, across and down a gravel driveway that leads to the garage structure, and then eventually through to a lower-lying area some distance away. During this trenching, some underground rocks are discovered that would interfere with the pipe, so a jackhammer is used to break them up.
Eight-inch-diameter drain pipe segments are laid within the newly-dug trench. The larger size of the pipe makes the gluing and connecting process seem more challenging that it typically would be for the smaller-diameter pipe segments that Shawn uses in his other videos. It takes both Shawn and his friend some effort to get the work done, especially when connecting a forty-five-degree fitting used to alter the direction of the pipe system toward its final destination.
The pipe laid earlier to catch the canopy gutter’s downspout is covered over with dirt, and a portion of the pipe inserted through the side of the catch basin is trimmed down to its final size.
Near another post at the other corner of the canopy, another trench is dug leading to the main drain. Instead of using an expensive fitting to connect this smaller-diameter pipe with the larger-diameter pipe leading away from the catch basin, a hole is drilled in the top of the larger-diameter pipe. A ninety-degree fitting is then used to connect the two pipes, with the smaller pipe draining into the primary drain pipe.
Some more pipe is laid along the side of the garage opposite the canopy, to catch some eventual drainspouts on that side of the structure. More trenching is done for another separate run of pipe that will also be used to help drain the French drain that was installed behind the garage, and the pipe is laid for that.
Trenching continues for the large-diameter drain pipes running below the garage’s gravel driveway. Several segments of pipe are then installed in the trench, to bring it to the point where the drain pipes coming from the other side of the garage will connect to it. It again takes some effort to get the larger pipes glued and connected, with the small excavator’s bucket being used to help push the one pipe into the other pipe’s connector.
Two more trenches are dug to connect the pipes coming from the far side of the garage to the main drain pipe. Expensive Y-fittings are used for these connections.
A trench is dug below a fence, and then in the direction of a lower-lying area where the entire system will eventually drain to. The final segments of eight-inch-diameter pipe are laid, with the excavator once again being used to help push them together. With the pipe installation now complete, the trenches that remain open are filled in with soil.
Shawn returns a couple of times later on to check on the state of the system. It’s raining during the second visit, allowing him to show water coming out of the system’s outlet. Behind the garage structure, the water coming down from sloped ground is draining into the catch basin, although it appears to be going around the corner of the French drain to get there.
Subsequently, some natural debris ends up obstructing the catch basin, which results in flooding at the garage. Shawn’s friend’s wife is able to clear it, which allows some of the collected water to drain away.
At a later date, Shawn returns to show some modifications that were made to the system to help avoid such flooding, including a small berm and swale that were constructed along the edge of a neighboring property to help direct away the water before it even reaches the drainage system that was installed around the garage. Some of the holes in the catch basin’s grate had been enlarged, to allow at least some debris to pass through and out of the system, rather than clogging the grate and causing the sort of flooding that had happened earlier.
Shawn discusses some of the challenges encountered with this system, and he mentions that the lessons learned are being used by his friend when designing the drainage system for other building projects. He also briefly shows the initial work being done for the very early stages of a home build.