It should be pointed out to the customer, Durant recommends, that poor drainage affects maintenance directly and makes it an uphill battle. One can try many things--aeration, dethatching, pod top dressing--to pinpoint any particular problems. But the fact is that the cost of plant replacement, labor, and other factors can cost the homeowner two to five to ten times more than what it would have cost to do it right the first time.
One needs to look for what can be the potential causes for bad drainage and to deal with these ahead of time. Two of the main possibilities are surface and subsurface.
Surface causes for poor drainage have to do with improper grading, not sloping the surface sufficiently so that the surface water will run off to the appropriate drainage disposal. us important to build slope into lawns and patios, Barrett says. One-and-a- half inches appears flat but that can direct the water to where you want it to go. You can determine a slope by taking the length across the surface of space, 12 inches in a foot, times 1.5%, to tell how much the lower part of the lawn differs from the uphill side.
Other causes of bad surface drainage include the absence of drainage, insufficient drainage, or poorly placed drains, such as those placed too high.
Subsurface drainage refers to the water that flows into and then through the ground. This can sometimes be as important if not more important than the water on the surface. One of the big problems with underground soil is impervious levels of clay or other matter. If this is present, the water will soak into the ground just so far, hit this level, and then rise to the surface, resulting in standing water.
How can you tell whether or not this nonpermeable level is there? Dig down and take a soil sample, Durant says. Often that level is close to the surface, a foot, six inches, or even three inches, though you sometimes have to go down three or four feet. But if you don't deal with a hard level like that, you are in for drainage problems.
Another really important aspect, which affects both the surface and subsurface drainage, is the quality of the soil itself. Most commercially purchased soils have a very low hydraulic permeability, which means the water passes through the soil very slowly, says Durant. If you have soil that drains slowly, it puts more of a burden on the drainage infrastructure and on the placement of the pipes.
Sandy soils usually do not have a drainage problem. But you have to be careful, Durant says. Too much silt in the sand will prevent drainage. I was called in to repair a site where sandy soil was used, but nobody realized how much silt was in the soil. Silt is hard to see when the soil is dry; you see it only when it's wet. We were called in because the plants were dying and nobody knew why. Fertilizing them wasn't doing any good. The silt was sealing up the soil and preventing drainage. In a case like this it doesn't matter how many drains you install, they won't do any good.
Another subsurface condition to be aware of, Durant adds, is underground springs. Turning briefly to three draining equipment manufacturers, they all say that it'best to keep the drainage infrastructure as simple as possible.
Hardy Rost, president of Dura Plastic Products of Beaumont, California, explains that conventional drain lines go eight feet down to the main pipe, which makes it difficult to clean and maintain. With our system, the water is piped to the surface where it can be filtered and disposed of in any number of ways. It's easy for the landscape contractor to install and the homeowner to clean. It's right on the surface--just pull the grate off and easily clean it. This apparatus on the surface is designed to look a shady green so it won't attract attention.
Mike Fallon, vice president of sales, NDS, Woodland Hills, California, says, We don't make the pipes, but we simplify the drainage process through our offerings of catch basins which capture the water and channel it into the sewer system.
Although drainage is not new and basic technologies have long been in place, this little market niche can prove to be a bonanza to the landscape contractor. Without proper drainage, all the money spent on landscaping could literally go down the drain.
Durant points out that there is a new movement developing, which innovative landscape contractors can latch onto to make this somewhat bland service a little more, well, sexy.
There are two schools of thought on this subject, Durant explains. The first is the traditional one, which says you want to capture the water, channel it, and transport it away as quickly as possible. But the second, newer school of thought says, no, just the opposite. Let's control the water on site and infiltrate it in the right amounts.
This is called the low impact method. It's more environmentally oriented and is more common in Europe, though it is not being introduced in this country. It's also called a nonpoint drainage system, which allows water to infiltrate the property in a healthy manner, as it would in a forest. There are many varied techniques to accomplish this.
For instance, one is a green roof, which absorbs rain water, instead of running it off onto the ground. This concept has expanded to every major city, Durant says. It's a new field, but one an enterprising landscape contractor can become involved in as an aspect of his drainage services.
Another variation, Durant continues, is an alternative to gutter pipes, which drain excess water from one house's property, but often onto a neighbor's. The new device is a mechanism which sprays water out onto the lawn. This provides even more distribution.
Still another variation is drainage into rain barrels, to be used later as irrigation water.
Remember, none of these have to be used in isolation, they can often be used in conjunction with each other.
There are now new technologies that will make concrete pervious, so that the water, instead of running off, will drain through patios, wall ways, and roads. In addition, with the use of particular soils and ways of tilling the ground, water can be stored deep within the ground.
There are also community movements afoot here, such as no curb design, which basically puts water underground. According to Durant, The present system of communities running off their water to large centralized plants where it has to be purified before it is put back into streams and other waterways is very expensive, especially with new environmental laws.
The low impact drainage option, Durant says, Dis still small, but rapidly growing. There are conferences going on throughout the country, and every major landscaping company is becoming involved, if only to a small degree. Any landscape contractor, large or small, who wants to investigate some of these possibilities, can find new and profitable drainage services to offer his customers.