Heavy clay soil is often compacted when a home is built and can lead to standing water in the lawn if the area is not graded properly. Later, poor drainage in the lawn can kill the grass and turn the turf into a mud pit. Several kinds of drainage systems, however, can be used to remedy the problem after the fact.
Box drains are designed to collect water from the lowest points in a lawn and carry it away in an underground pipe. They consist of a plastic box to collect the water and a drain grate that is installed flush with the soil surface. Openings on each side of a box drain allow corrugated pipe to be connected to drain the water away or, on the uphill side, to accept water collected from another drain. A series of box drains can be installed with a network of underground piping to collect water from various points in the lawn, as well as from gutter downspouts.
A french drain uses corrugated piping similar to that of a box drain, but, unlike a box drain, no inlet is visible on the ground's surface. Instead, the underground piping is perforated, which means it has slits that allow water to seep into the piping from the surrounding soil. In order for this method to work, the pipe must be installed in a trench lined with drainage fabric, a product through which water can seep but that prevents soil and roots from clogging the drain pipe. The trench must run continuously downhill with a minimum 1-inch drop every 4 feet. The pipe goes at the bottom of the trench, and then gravel is added to surround the pipe with a highly porous medium to facilitate the movement of water from the adjacent soil.
A surface drain, also known as a swale, is excavated along the low-lying area of a lawn so that rainwater flows away quickly. This kind of drain looks and functions best as a broad, shallow ditch rather than a trenchlike feature. It needs to drop a minimum of 1 inch every 4 feet and can be planted with grass. If the slope drops more than 1 inch per 1 foot, then the drain should be lined with rocks to prevent erosion. This type of drain can be a landscape feature if it is lined with decorative river rocks and planted with water-loving plants.
A dry well is an effective alternative to the other drain options when a lawn has a single depression that would be difficult to drain with underground piping or a surface drain. When a dry well is used, water is not drained away downhill but is allowed to percolate straight down in a gravel-filled pit. The pit should be lined with drainage fabric before gravel is added to prevent soil and roots from clogging the pit in the long term. A dry well also can be used as an outlet to receive water from any other lawn drainage system.
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