Understand the common language of hand excavated french drain installation. I will use this article to give definitions of commonly used words that identify concepts, methods and materials used in the installation of hand excavated french drains and other groundwater removal methods.

1. Hand excavated french drain: An aqua duct that is hand excavated to contain a grade of approximately 2″ per 10 lineal feet, with straight clean sides and a flat bottom, and with a hard finished bottom grade.

The hand excavated french drain is most often, approximately 12″ wide and 8″-18″ deep, when installed on a flat surface, and travels a lineal distance of approximately 50 lineal feet per drainage system. Flat areas are the most difficult to engineer grade.

The hand excavated french drain will contain a 3″ ads perforated pipe, 3/4″-1 1/2″ washed river rock, weed cloth, and will be installed to vent to a dry well or a day lighted vent, in most cases, unless pumping of the collected groundwater is involved.

The washed river rock is usually exposed on the surface of the hand excavated french drain, for maximum groundwater collection. Downspouts may also be installed next to the perforated pipe, laying on the bottom of the french drain aqua duct, and vented in solid 3″ abs glued pipe and 3″ ads solid flexible pipe, laid on the bottom of the hand excavated french drain aqua duct, which is excavated to vent, downhill, to the dry well, storm water retention pond, or a daylighted vent.

2. Dry well: A hole that is hand excavated in the ground, with no debris, straight sides and a flat bottom, usually 4 feet in diameter by 4 feet deep, for most residential properties. Perhaps larger in some cases.

This is where the groundwater will be initially stored until the dry well perks it out.

The dry well is a groundwater mitigation area, where the groundwater collected in the hand excavated french drain groundwater removal system is vented and soaks (perks) out through the bottom of the dry well into the water table below the crust of the earth.

Cracks are formed on the hard bottom of the dry well as the groundwater soaks out. Just like when a lake goes dry. When the dry well goes through periods of being wet and dry, cracks enlarge on the bottom, this increases the speed of groundwater soakage as time goes on.

The term (perk) is often used to describe the process of soaking into the ground, the groundwater, and is the same principal that makes a septic tank work. Although septic tanks also use a drain field overflow system. French drains are cleaning already just muddy groundwater, not filtering out solids, like a septic tank does.

The dry well can be river rock filled and supported, or contain a concrete cylinder tank installation, that is surrounded by perhaps a foot of river rock and then covered with dirt and a concrete top. I do not install these, as a general rule. They are mandated in many cases of new construction by the cities or counties. Explanation to follow.

Concrete cylinder tanks are the present day, darling home drainage method, suggested by many cities and counties around the United States.

The concrete cylinder tanks can be anywhere from 4 feet in diameter up to many feet in diameter, depending on the projected amount of groundwater coming to it. Concrete cylinder tanks with holes in the sides, like I am trying to describe to you herein, also perk the groundwater into the bottom of the, in that case, machine dug huge hole called an excavated dry well.

These systems perk just like the river rock filled 4 foot deep by 4 feet in diameter river rock filled and supported dry wells do. No difference at all.

In my opinion, many of these large tank installations that do not spread out the saturation of the groundwater on the home site. I recommend spreading out the perk process in various areas of the home site by locating them in areas where the rain drain discharges are installed. Use perhaps 4 river rock supported dry wells, instead of one huge tank.

Homeowners with large tank installations could one day see a back hoe fall into it, as they are just covered with 2 feet of soil with a concrete top, which could crack under the weight of a machine. Once installed, no one remembers where they are, or even thinking about future machine use on the property.

These systems have serious safety implications that need to be addressed prior to using them, in my opinion. I have seen the city of Portland, Oregon, for example, mandate this type of system, to be located directly above an adjacent homeowner, who would have been seriously damaged by that amount of water being vented into the ground in one location. What out. Don’t just jump because they say so. Look at this as a value added alternative to bad drainage and future potential law suits from some back hoe operator, now out of work because he fell in a hole 15 feet deep with his machine, on your property. Do you think you can successfully sue the city. Think again.

The use of more dry wells, smaller rock filled dry wells, is a better alternative, from the standpoint of safety, environmental impact, geology, and splitting up the groundwater soakage into more than one area for “green” groundwater disposal of the collected water, rather than sending it to the storm sewers, which in many areas can overflow the sanitary sewer systems.

3. Perforated pipe: 3″ or 4″ ads perforated pipe is plastic pipe that has slits in the pipe, to allow the groundwater collected within the hand excavated french drain to enter the pipe and flow quicker to the daylight vent or the drywell.

Most of the groundwater runs on the bottom of a properly hand excavated french drain. The perforated pipe only acts to speed up the process of the groundwater during heavy rains.

4. Day lighted vent: A way of venting a french drain that allows the groundwater that is collected in the hand excavated french drains to continue downhill on the bottom of the hand excavated french drain grade, to an appropriate place where the groundwater can spill out, at the ground level, and spread out, without causing a neighbor to be flooded by the groundwater.

Ditches and creeks are good areas to accomplish this, and install a day lighted vent, if the grade can be maintained with adequate slope in the french drain, to allow the groundwater collected to get to the day lighted vent.

Dry creek beds are also used for this purpose, and also make great garden and lawn architechure.

5. Rain drain discharge: The downspout/gutter venting pipe, usually 3″ or 4″ abs pipe, converted to 3″ or 4″ ads solid flexible pipe underground, where many turns between that point in the system and the area the groundwater will be required. The groundwater must flow downhill on the bottom of your excavation, without the pipe even installed, eventually spilled into a dry well or spilling out on the ground well away from your home site or foundation, depending whether you are installing lawn drainage or foundation work to prevent groundwater in your basement or crawl space.

6. Sump well: A dry well or sump pump enclosure that contains a sump pump, because the ground does not perk well, or it is located to pump groundwater already in your crawl space or basement. Usually constructed in areas of basalt rock formations or severely below grade swampy areas that are actually in a flood plain, but where you are not just pumping the river as your source of proof for the sump pump being required. Contrary to public opinion, hand excavated dry wells perk well. They require days to weeks usually to break in and form cracks on the bottom of the dry well. The clay soils of the pacific northwest of the United States makes wonderful hand excavated french drain and dry well systems.

A sump well requires a solid electrical conduit from the power source to the sump well, for electricity to power the sump pump.

Sump pumps may be constructed and plumbed within basements and crawl space areas, as a last resort only, to pick up groundwater not collected within exterior foundation exposed river rock hand excavated french drains. If you don’t have french drains installed right. Just be happy with pumping for duration of the time you own the home, and perhaps even be forced to fix the problem to sell it, after the homeowners lived with the home drainage problems all those years. They thought they would never have to pay up and fix the problem, so they just lived in the moisture. After all, you can’t see or prove lung damage over night, so no one worries. Kind of the old mad magazine character, Alfred E. Newman “What me worry?”

Sump pumps should be used as a last resort only, not as the first method to solve groundwater entry below grade. No matter how the sump pump guys try to fly that sump pump guarantee b.s. up your posterior, sump pumps never stop groundwater from entering below grade. That includes exterior sump pump installations that are located at the end of a ditch on your foundation wall, and that are connected to a sump well and sump pump installation that is by code located too close to the foundation, and is nothing but a flat long ditch around your home, that only makes the problem worse, and also invalidates any professional home drainage contractors solution, without completely removing the former installation, if possible, which most often it is not. So the homeowners have just screwed up any chance they would have had to solve the problem, but locating the wrong system, in the area the correct one needs to occupy.

Sump pumps are usually not needed, if professional exterior foundation hand excavated french drain groundwater removal systems can be installed and plumbed around 18″ from your foundation wall.

The average hand excavated french drain installation is located around 18″ from the foundation wall. The area will contain a raised compacted splash block of dirt and clay, to run rainwater from the homes wall to the inside of the hand excavated french drain. Gardening and digging up your foundation wall is history. You will learn to use large containers for flowers and trees against your home. Cap all sprinkler lines near your home and water by hand. Say goodbye to those plants or more them. I advocate container gardening next to the home, without digging up and loosening the soil at the foundation wall, for best home drainage results, no matter what is for drainage groundwater prevention.

7. Drainage rock: Usually 3/4″-11/2″ washed river rock used in hand excavated french drains and dry wells. Never use pea gravel, 3′4″ minus basalt rock, or sand. They are not adequate for professional installation. Cheaper, yes. Better, no.

8. Excavation dirt: The dirt and clay spoils that is removed from the hand excavated french drain dry well or day light vented system excavation. It is most often used in the landscape, rather than hauling it off the property in a drop box. The drop box alternative can get expensive, when adding the labor to get it out to the box. Make berms, raised beds, mounds and other landscape forms.

The dirt is replaced in the hand excavated french drain with pipe, weed cloth and drainage rock.

9. Engineered grade of a french drain: The objective is to excavate the hand excavated french drain on a flat surface. This is accomplished by excavating first with a point shovel, and then with a flat front shovel.

When there is no slope to use, such as a 50 foot long area, you must engineer a grade of approximately 2″ per 10 lineal feet in slope. The hand excavated french drain aqua duct will be deeper at the dry well around 18″ deep, while the dry well itself will be around 4 feet deep itself.

On a flat surface, the excavation must be shallower at the top end of the hand excavated french drain system, and vary between 8″-18″ in finished aqua duct french drain depth, in which your perforated pipe is pinned down at the top of the drainage system, on the bottom of the aqua duct, with 3/8″ in diameter re-bar, about 12″ long, staked across the top of the perforated pipe and weed cloth, under the finished rock level, on the shallow ends only.

This is just a starter. Read on for learning advanced home drainage skills and how to deal with home drainage contractor confrontational stories, contentions and scams.

1. French drains should be further defined by using the words “hand excavated french drains”, rather than just french drains. The difference is worth the effort to understand. A hand excavated french drain has more groundwater removal ability during hard rains than any other type of french drain. The materials in the french drain and the engineering that determines the slope and the way the french drain is vented also sets it apart from other french drains with respect to quality. Accept no substitute, always specify professionally installed hand excavated french drains for long lasting quality and optimal performance.

2. French drains, specifically hand excavated french drains, are aquaducts that collect and vent huge amounts of groundwater when they are professionally installed and plumbed.

Hand excavated french drains remove groundwater from foundation areas of the home. The groundwater will likely cause leaking into basements and crawlspaces if not vented from the foundation area during hard rains.

The leaking into lower crawl space levels causes foundation spot footings to sink, post and beam structures to sink and dryrot, and basement walls and floors to crumble and deteriorate. Eventually the doors will jam, windows will break and jam, and especially hardwood floors of the home will start to show cupping and other potential damage caused by the home sinking slowing over time.

3. French drains are usually installed approximately 12″ wide, and contain a perforated pipe for the groundwater overflow. Most of the groundwater runs on the bottom of the french drain. The french drain may also contain a solid pipe that connects the rain drain discharges at the side of the home, and vents the downspouts to the drywell also. Both pipes are placed on the bottom of the hand excavated french drain to vent the groundwater in perforated pipe and the downspouts in solid pipe.

4. Hand excavated french drains have straight sides and a flat bottom with no debris or loose dirt what so ever. Hand excavated french drains are much more difficult to engineer and excavate, but they last longer and perform better because debris does not slump to the bottom of the drains plugging them in time due to the busted up sides that a trencher gives you back for your effort. River rock holds the sides of the french drain aquaduct straight and allows more air in the french drain, which allows the french drain to vent more rain water quicker, as the flat engineered and graded bottom speeds the groundwater removal.

5. Hand excavated french drains further distance themselves from other types of machine installed french drains, or so called french drains, because of the careful way they are excavated, which allows the drainage contractor to avoid busting up irrigation systems, gas lines, electric conduits, telecommunications wires and cable lines for computers and tv, just to name a few.

A utility locate is always advised prior to any excavation. Irrigation lines, old rain drains, and old french drains are never marked with a utility locate. If you use a machine to trench, your home irrigation system will be trashed. Besides, a ditch witch does not have eyes or any mechanics that can ascertain, excavate and create a grade of 2″ per 10 lineal feet on a flat surface in areas that are flat themselves. They are absolutely worthless drainage tools for professional solutions.

6. Hand excavated french drains are attractive to look at when a uniform clean cut line is formed by the exposed river rock along the 12″ wide french drain. French drains with exposed river rock blend into garden areas and other landscaping features, and are used in bio-swales, dry creek beds and other storm water retention ponds and lakes.

Exposed rock drywells look nice with a bird bath set on top of a 4 foot in diameter circle of river rock. Many professional gardens use this opportunity to combine form and function.

7. Hand excavated french drains can be installed in lawn areas in wet low grade or flat areas. While these types of hand excavated french drain groundwater removal systems do not work as effectively or as fast as the ones with exposed river rock on the surface, they never the less most often offer the only alternative to getting rid of soggy marshy areas.

The same system on a larger scale is used in agriculture when farmers turn unproductive swamp land into farm fields within a year by tiling the land. A tiled system is a huge, wide french drain dug with a back hoe, by someone very skilled, who can excavate a grade for the bottom of the aquauct that will flow the groundwater away quickly to a pond area or some other lower hillside vent area. More information is available on this website on the subject of agricultural tile science under the archives section of the home page..

The typical lawn drain system french drain is covered with weed cloth, as all hand excavated french drains should be, and then covered with 3″ of dirt and 2″ of sod to finish the french drain, or 5″ of dirt with the homeowner re-seeding that area. These types of hand excavated french drains start with a 12″ strip of sod being cut with a hand sod cutter, and a circle of sod 4 feet in diameter cut where the dry well will be located, if a drywell is used.

Another option for the grass is: All sod is cut in 12″ widths and 12″ lengths and stored on plastic in a shaded area and kept wet. When completed, the lawn french drain is installed with the dirt and sod layers placed on top of the weed cloth covering the rock in the french drain.

Lawn installed french drains will wick groundwater into the french drain from approximately 6-10 feet or more on both sides of the french drain and pull groundwater from these areas in the top 18″ of soil, where most of the groundwater from rain is concentrated, where formerly the groundwater would have stood for days or weeks during and after hard rains.

Hand excavated french drains are long lasting and functional. When you are doing research into the structure of french drains, specify hand excavated french drains with 3/4″-1 1/2″ river rock, and the engineering that I have shared with you in this blog on home drainage.

Never use gravel, as some french drain articles advise. This has too much minus in it and will clog the system, if it ever works at all. That type of french drain attempt does not contain enough air and the gravel compacts into a worthless gravel filled ditch, many times wrapped in a bundle of road cloth or weed cloth, with a perforated pipe in the middle, which is off the bottom of the excavation, where the groundwater will run. This makes even less sense to us professionals than it does to you right now.

Never use the perforated pipe with a sock over it. This is for foundation footing drains, and even then are misunderstood as to their placement and plumbing. They clog and do not function for long due to the fact they are easy to plug with dirt that is usually placed directly on top of the pipe and sock. If the bundle of road or weed cloth method filled with gravel is used, this will clog as well and is simply worthless in function.

So that’s about the nuts and bolts of it folks. Lots of energy is required to pull it all off right without turning your entire landscape into what perhaps resembles “craters of the moon” national monument.

You must be involved early planning, permitting, as well as during the architects foundation grade recommendations, the home siting on the building land, environmental and neighbor considerations as well as others. You are looking at lots of wheel barrows up and down hills with rock and dirt, even with the proper information, completed in the right order and way.

You will find more detailed information by reading the home drainage category you are interested in under the archives section of my home page.

Absolutely nothing beats the work of trained home drainage professionals who do it every day. Eyes and experience are not bred into the nature of the home drainage installer. The amount of patience, strength and energy that it takes to plan and excavate cosmetically a hand excavated french drain groundwater removal system can be large depending on the individual project.

And last but also important is the reality that there is no one quick fix for every home drainage groundwater problem. Sometimes the best call a home drainage contractor can make is to explain the unknown factors that may be causing the problem and pass on bidding the project all together if situations exist from former drainage attempts that prevent the installation of hand excavated french drains to provide them a solution.

Sometimes no good alternative is available because of the quantity of groundwater, the location of the groundwater, the source of the groundwater or the depth of the groundwater that is positively identified as a year round running spring, not apparent only when rains saturate the area. I stress the words “year round” as mandatory qualifying data with respect to identifying the source of the groundwater as a spring.

The excavation is plumbed with a flow enhancing perforated pipe laid flat on the bottom of the aquaduct, usually a 3″ perforated pipe is adequate for residential home drainage solutions.

The french drain aquaduct is filled with 3/4″-1 1/2″ river rock and a layer of weed cloth laid shiny side up, placed 4″ from the top layer of the french drain.

The weed cloth protects the french drain from weeds invading your home drainage system, and prevents dirt and silt from accumulating in the layers of the river rock.

A layer of weed cloth is placed towards the top of the french drain to allow air passage and better groundwater passage to the bottom of the french drain on which 90% or more of the groundwater will actually run.

Never use a perforated pipe with a sock on it. This is for foundation footing drains, and clogs easily, as it also prevents the perforated pipe from collecting the rainwater fast enough in heavy rains. Just don’t go there. The pipe with the sock is not a good method in my opinion.

There are many ways that self professed french drain installers who are not educated to the fine points of home drainage can mess up the concept and performance of a french drain. There are literally dozens of convoluted concepts created in the name of home groundwater removal that are called french drains.

A true french drain is a hand excavated french drain as described above. French drains were always hand excavated, from the beginning, hundreds of years ago to the present. No exceptions.

A french drain must be engineered to cover no more lineal footage than would allow for the creation of a hard finished bottom within the french drain, a grade of 2″ per 10 lineal feet or more sloping to the vent, which is either a daylighted vent, sump well, or a hand excavated drywell.

If a drywell approximately 4 feet deep is used, the typical length for each french drain is approximately 50 lineal feet if the depth is 18″ at the drywell, and 8″ deep at the top. This would only apply to a french drain excavated on a flat surface.

If you have a continuous downhill grade which is in itself 2″ per 10 lineal feet or greater, you could follow the grade maintaining the same depth to a daylighted vent hundreds of feet away theoretically. If you are working with a flat surface over 50 feet long, create two drywells and split the grade with the french drain sloping from the middle out to both sides to drywells with the depths advised above.

If a hand excavated drywell that is 4 feet deep by 4 feet in diameter is used, which is most common, as OSHA will not allow workers in a hole over 4 feet deep without supported sides during excavation, the french drain groundwater removal system is hand excavated to a depth of 18″ at the drywell and slopes upwards from the hand excavated drywell as it is being excavated to the top of the hand excavated french drain system at a depth of 8″, which is a 2″ per 10 foot slope.

Read other articles on this website for instructions in the order of work accomplished and other fine points of hand excavated french drain installation. A french drain is a hand excavated french drain, 100% of the time. No exceptions.