If you are a “do it yourself” type and are preparing to install hand excavated french drains around your home or through your property, observe a few cautions, preparations and material choices and include them in your plan in the correct order. I will use this article to red flag some common considerations required for a safe and successful hand excavated french drain installation.
First off, always order a utility locate as part of the initial feasibility study concerning your hand excavated french drain installation. When contemplating a french drain installation, first work the problem from the proposed vent method location forward to the proposed area where the french drain will be located. Ask yourself what type of venting method is most appropriate for your groundwater removal system.
Estimate the amount of groundwater and/or downspout water to be collected. Review the particulars of your site topography and how they impact your drainage plan. Consider the potential impact of the proposed water collection venting method to adjacent neighbors and their homes. Will a day lighted vent be the most beneficial way to dispose of the collected groundwater?
How about a river rock filled dry well? Do you want a huge tank type installation with concrete cylinders that just sit on the ground in the drywell and is surrounded with rock, leaving an open center and a top covered with concrete and dirt? Many jurisdictions suggest this method as part of a french drain installation?
This type of dry well is costly and leaves the owner with a large hole covered with 2 feet of dirt and a concrete top that can crack in time. This type of drywell is usually too large to be excavated by hand as well. The top may cave in if a backhoe drives over it, long after the person installing it has moved from the home and no one knows where it is. Utility locates do not show the location of these drywell tanks. Is that type of dry well system going to work for your safety and potential future liability? When all is said and done, the water still perks into the dirt on which the concrete cylinders are laid.
OSHA cautions you from putting a man over 4 feet deep in a dry well excavation without bracing to protect the workers from a cave in.
Consider how many lineal feet that your french drain installation will travel. Do the math. Can you achieve a 2″ per 10 lineal foot drop in grade on the bottom of your french drain installation? If it is not possible to achieve this grade, you may need to break the line into 50 foot lengths and numerous dry wells to achieve the results you desire.
Is the rock going to be exposed along the french drain, for maximum groundwater collection? Consider these materials to achieve best results and long lasting service of your french drain installation. Are you able to get 3/4″-1 1/2″ river rock for your hand excavated french drain groundwater removal system in your part of the world?
What else might work like it that is available in your area? Never use gravel or sand, or bark material. Nothing with fine material in it at all. Do not place rock, dry wells, sump pumps, and/or perforated pipe directly against your foundation wall and expect the groundwater not to run directly down your foundation wall to the foundation footing,which is exactly what most sump pump installers want to happen.
It fools the homeowner into feeling helpless and without any other alternative. Sump pump installers are full of b.s. stories about underground rivers and springs under your home and in the neighborhood in general.
Only place rock on the foundation wall if needed for the properly engineered and vented foundation footing drain, and then make sure you know what you are doing, and that it is the only alternative available to you to solve your drainage problem.
Never use wrapped perforated pipe with the sock or mesh. It slows or prevents the collection of groundwater into the perforated pipe when water is coming at a heavy pace, and is used in footing drains, not in hand excavated french drains. The perforated pipe is only an overflow in a properly engineered hand excavated french drain. Most of the groundwater will run on the bottom of your hand excavated french drain, and never build up in the perforated pipe at all if all systems are properly engineered.
Have you covered your grass areas with plywood to protect them from looking like the covered wagons were just passing through. Keep your area clean and in condition to have the grass raked out when done. This makes for a great cosmetic effect, keeping the landscape in good condition.
Surround the dry well excavation with plywood to protect the edges and give your excavation a cosmetic look when completed. Cut the sod to be replaced over the drywell in neat strips of similiar depth about 12″ long by 12″ wide and replace the sod in lawn areas where you do not wish to have an area of rock become part of the landscape.
Have you estimated the amount of soil needed to raise and compact a better grade at the exterior foundation stem wall and determined where and where not this splash block should be constructed and compacted with a hand compactor only?
Are there foundation vents or other objects like window wells that prevent you from raising the foundation splash block grade at the foundation? Did you do the grade correction, and the compacting of your splash block prior to the french drain installation which will be located about 18″-24″ from the foundation wall? Do you need to step further away from the foundation wall for placement of the french drain due to existing trees and foundation plantings, or irrigation systems? Have you estimated the amount of soil that will be hand excavated from your french drain system? Where is the excavated soil going to go that was not used to compact splash blocks? Are you going to use the excavated french drain soil for raised beds in the border areas of your landscape? Do you need to drop box the soil off the property? How much rock will you need to fill the french drain excavation areas after the pipes are laid?
With respect to the installation of french drains, “a stitch in time saves more than nine, and makes the difference between success and failure, 100% of the time.” aaahomedrainage.com
Did you remove all loose dirt from the french drain installation and finish the bottom absolutely smooth and hard for best groundwater running ability? Have you contemplated using machines for excavation? Do not use machines if you want it done right. Machines are for gardeners, not professional hand excavated french drain installation.
Did you hand excavate the french drains from the bottom of your system, starting at the daylight vent or drywell looking up the grade? An optical illusion exists if it is excavated any other way. Your results will suffer or fail without this performance standard.
If you feel confident that your understanding of what I have said is understood and clear, and that you have the ability from a planning and physical strength point of view to accomplish the installation of your own french drain system, read this site for more detail on the process of hand excavated french drain installation for best results. Good luck follows preparation my friends.