Hand excavated french drains are indeed ancient technology carried forward into the 21st century.
What is a hand excavated french drain? I get this question many times a week in my business. Hand excavated french drains do not need to be hard to understand.
A hand excavated french drain starts with a hand excavated aqua duct that has straight sides and a flat bottom.
The french drain is approximately 12″ in width and averages 8″-18″ deep per 50 foot section of french drain that is installed.
The hand excavated french drain aqua duct contains an ads perforated pipe, either 3″ or 4″ in diameter usually, and is backfilled with 3/4″-1 1/2″ river rock, while also using weed cloth to prevent most silting of dirt into the french drain.
Hand excavated french drains usually vent into a 4 foot deep x 4′ foot in diameter dry well, also filled with 3/4″-1 1/2″ river rock. The hand excavated french drain may be daylighted vented, which is where the groundwater spills out directly on the soil after a continued downhill grade of at least 2″ per 10 lineal feet is achieved, taking the groundwater away from the home or yard.
The daylighted vent works best on sloped sites, where the groundwater being vented will not run onto a neighbors property and cause them a groundwater problem as well.
Many times the sod is replaced over the hand excavated dry well and the dry well also contains weed cloth, with 6″ of replaced dirt and sod reconstructed over the rock and weed cloth.
A layer of weed cloth is placed approximately 4″ from the top layer of the grade level rock, if the rock is exposed on the surface, which is the best way to collect groundwater quickly, as it comes hard during strong rains.
Hand excavated french drains are usually installed about 18″ from the foundation wall. A raised and compacted grade at the foundation wall is created, when possible, to enhance the rain runoff from the foundation area into the hand excavated french drain.
The bottom of the french drain is hand excavated to create a grade finished with a flat shovel of 2″ per 10 lineal feet or greater. We are making pottery in the earth that runs groundwater on the bottom of the french drain aqua duct.
Most hand excavated dry wells perk well when broken in, which is usually within days to a few weeks. If the site does not perk, a sump pump well can be created to vent the groundwater, if there is not enough grade to install an overflow to gravity flow the groundwater collected in the sump well to the street or woods.
If the grade is sufficient to allow the creation of the slope and day light vent, that is to say spill out on the surface well away from the home and not onto a neighbors property, this may be the best way to vent a hand excavated french drain groundwater removal system.