The world of home groundwater drainage and home groundwater removal, specifically with hand excavated french drains, is better understood if you speak the language.
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.