How to Assess Garden Drainage
Garden drainage is important for having a healthy garden and for the safety of the structure of your house. A yard where there are drainage problems will be a nightmare in the long-run because all the water-logging can lead to serious damage to the foundation.
If you are planning a new garden it is important that you assess the drainage situation of your garden prior to any planting. You may have picked a site or section or your yard based on the amount of sunlight it receives and how much wind exposure it has. Now you are ready to check the drainage in the area – you should dig a hole of about 12 inches in diameter and makes it twice as much in-depth. Now fill the hole with water with your hose till the halfway point. Check the hole periodically and it should ideally be completely drained in a 24 hour period. If there is water after 24 hours it is an indication of drainage issues and you should consider ways to improve the drainage in the area before moving forward with your garden plans.
One of the easiest and most effective ways of improving drainage is to bring in additional dirt or soil into the garden. By creating ups and downs of hills and slopes, you can help the water drain away better. If your garden has extremely hard clay, you can add a few inches of good quality topsoil which has better drainage and is generally easier for plants to establish themselves in during the early seasons. If these changes to the soil seem to be ineffective, then you should consider installing pipes to improve your garden drainage. Properly installed drain pipes will be invisible once the garden is planted and will go a long way in helping move the water away from the garden and the foundation. So, make sure that your pipes are laid in such a way that they direct the water away from the house and its structure.
Sometimes over time, a garden may develop drainage problems. Before you can find a way to fix it you will have to find out exactly what is causing the problem. The best way to do this is during heavy rainfall or immediately after. If you step out into your backyard while it is raining, you will get an immediate understanding of where your drainage problem is starting. If the additional water is puddling below a downspout or if it is accumulating between two raised beds before spreading all over, you know that your solution will involve addressing the drainage situation under the downspout or in the area of the raised beds. By spotting these problem areas early and addressing them immediately you can prevent a serious garden drainage issue.
A French drain, drain pipes or tiles, dry wells, effective use of landscape plantings can all be solutions to water drainage problems in the garden. You can use one or a combination of them to help the water drain away quickly and efficiently. Whichever method you choose to remember to follow the natural tendencies of your landscape: water does tend to flow downwards; notice the parts of the garden which are already a little soft and soggy and ensure that you do not add in any way to the water in that area while planning your drainage. In most cases, poor garden drainage is fixable with some thought, planning and digging.
During your assessment, if you find that there is noticeable accumulation under the deck or close to the foundation, you should get professional help promptly. Garden drainage is not just a matter of having some healthy and attractive plants but a significant issue for building safety and stability.
How To build a French Drain?
Dig a trench from the problem area to your new desired drainage area. The water has to go somewhere. In your case, I’d suggest the obvious location of out letting the trench at the bank of the creek or directly into the creek.
Line the trench with permeable landscape fabric or what’s also known as Geotextile. Be sure to leave enough excess up the sides so you can fold it over on itself and ‘seal’ your trench after its backfilled. This prevents dirt from clogging up what you accomplish in Step 3 and Step 4.
Lay 4″ perforated pipe in the bottom of the trench. Black ‘flex pipe’ or ‘sock pipe’, also known as weeping tile works well here. You can get 50′ rolls at larger hardware stores.
Backfill your trench with 3/4 clear gravel or round drain stone. There are a couple of different aggregates that will work here just make sure they’re clear (meaning clean, meaning no sand, silt or clay in the mix) when you order it. You’ll need more than you think. Rake out the gravel and level it being sure to leave the top grade of the gravel a few inches below the top grade of your trench so you can put soil on top and then plant grass or lay sod.
Fold the edges of the Geoxtextile over the gravel to ‘seal’ your french drain. Backfill the rest of the trench with soil, salvaging what you can from your initial digging mission.
Plant grass or lay sod
Drink beer and tell yourself that next time you’re paying someone to do that.
Installing Drainage Systems
Installing drainage systems is not entirely a simple matter but with a little know-how and by understanding the process by which drainage works, you will be able to do it yourself with a minimum of difficulty. Installing drainage systems is like replicating a larger scale agricultural system but scaling it down for the domestic application.
Understand the Principle
The most important point about designing and installing drainage systems for your home garden is to take into account that the water has to be able to move from the surface to the drain installed under the lawn.
Drainage systems work on the principle that water will always flow to the lowest point so you have to design your system so that the water will travel through to your gardens lowest point and from there it should either soak into the ground or flow away into a ditch or the municipal drainage system.
Initially, before you begin installing drainage systems, you will draw on a plan the area you wish to drain so that you understand it in theory and can follow through practically. When you begin to lay the main pipes, you first need to mark out the design from the plan. Use a can of spray paint or funnel some sand into lines.
Step by Step
1. Cut the grass out in strips about 5 inches wide and leave aside near the drain run. Then, dig out the run. A trenching spade is the best tool to use. Start with a depth of about a foot and dig so that the slope of the run towards the intended flow of the water; approximately 1/5 of an inch should do it. It is important when you are installing drainage systems that at this point you let some water from a hose run through so you can gauge if the fall is sufficient. The water should flow smoothly down the trench.
2. Upon completion of digging the first trench, fill it with about ¾ of an inch of ¼ to ½ inch stone then lay a piece of 3-inch perforated drainage pipe on top.
3. The next step to installing drainage systems is to back-fill the trench leaving the clean stone around 3 inches from the top then add the soil you initially dugout. Pat, it down firmly and replace the grass you removed.
4. Finally, make a series of smaller trenches at 90 degrees to the drainage pipes across the lawn, using a spade at 16-inch centers and to about 3 inches deep. Fill with washed sand. The slits should connect with the washed stone over the main pipes so if you are able to feel the stone with the spade as you build the slit, you know you are doing the right thing.
Over the ensuing months, installing the drainage system is replaced with maintaining it. You will need to top-dress the lawn with washed sand in order to build up a layer of sand at the base of the grass plants. This will enable the rainwater to penetrate the surface, travel down in the sand slits and into the drain.
So you see, installing drainage systems is not too complicated but you will need to put some hard labor into it. Once you have the design, laying out the pipes and digging the holes is the hardest thing about it.