How to Solve Lawn Drainage Issues
It rained last week. Your lawn still displays large puddles of water, and they are not going away, even though it’s been sunny and dry for a few days.The neighborhood kids love to play in the big puddles, which is as natural as the rain itself, –but your lawn clearly has drainage issues.
Water laying on grass for any period of time is a bad thing. Aside from being a prime breeding ground for mosquitoes, excessive water laying on the surface will eventually leach nutrients from the soil, weaken and kill the grass roots by depriving them of air and leave less than attractive brown dead spots on your lawn.
Identify the Source of Water
To identify the source of water and why surface water on the lawn does not drain quickly, look for these conditions:
- Roof leaders or down spouts that direct rainwater on to the lawn.
- Surface grading that is sloped toward a walkway, structure, or house foundation. The impermeable surfaces act as a dam, preventing drainage in that direction.
- Adjacent properties that may have been top dressed and the elevations raised, draining water to lower surrounding areas including your lawn.
- Very flat grading that has no perimeter swale* to drain water. If the surface is absolutely flat with no drainage, water has no slope or direction to drain and will remain static.* a swale is a very shallow ditch with gently sloping sides.
- Incorrect, poor quality grading that has left major depressions in the center. It’s no surprise that water always collects and becomes trapped in the low areas.
- Hardpan subsoil. Hard clays and hardpan are impermeable to water and prevent surface water from percolating into the ground. Hardpan soils can be as little as a few inches thick, or many feet thick.
Potential problems must be collectively identified before meaningful and economical remedial action can be effective.
Solve Drainage Issues with Common Sense
Once you have determined why water remains on the grass and drainage is poor, the source of the problem can be addressed and solved. Here are a few thoughts on solving drainage issues.
Roof leaders, gutters and down spouts:
Roofs collect an amazingly large amount of water which must be directed away from the foundation of the building to avoid damage. Most downspouts have a little bend at the bottom end, which merely drop the water a foot or two away from the wall, –conveniently on to the surface of the nearest lawn which may have inadequate drainage. Extend the down spout to direct water to a swale.
*Note that in most jurisdictions, it is illegal to connect roof leaders (downspouts) to the sanitary sewage system, which overloads sewage treatment plants and control systems with large amounts of rainwater.
Did You Know?…
A minimal rainfall of only one inch on one acre of land (42,560 square feet) results in the collection of an astounding 6,272,640 cubic inches of water, which is 3,630 cubic feet, or 27,143 US gallons of water. During the same rainfall, the average urban lot may receive between 2 – 3,000 gallons of water.
Surface Grading May be Your Solution
1. Surface grading should always be away from the foundation of buildings to prevent damage to walls. Check grading and fill and raise the elevation at the wall if it is too low. Grading should slope a minimum of 4′ away from the foundation. Doing so will prevent water pooling on the lawn adjacent to the building.
2. If water is collecting along a walkway or other level structure, consider correcting the grade just enough to allow the water to drain away from the structure from one end.
3. If your lawn surface is a lower elevation adjacent properties, collecting surface water from the higher property, consider top-dressing your lawn, raising it to the same elevation.
As an aside, avoid any confrontational initiation of a “tit-for-tat” “lawn-raising competition if surface drainage issues arise. Instead, allow for a shallow-sloped drainage swale between the properties. In this instance, a barely-noticeabe, good drainage swale creates good neighbour relations.
Perhaps raising the elevation of your lawn is not even necessary. Excavate shallow swales along the perimeter if adequate slope for drainage of the swale itself can be made available in doing so. An effective, properly constructed swale may be almost invisible, as it is contoured carefully and gently enough to be treated as any other section of grass.
4. Correct any depressions in the surface of your lawn. Use a tightly-stretched line and small pickets to identify low areas. Fill the depressions with topsoil, roll to compact the soil, and re-seed the grass. Most grading, if done correctly, will solve drainage issues.
5. If there is no other drainage available, consider constructing a French drain across the lowest area of the lawn to provide permanent drainage. Check with local utilities to verify location of pipes, gas lines, or wires prior to any excavation to avoid unnecessary damage and expensive repairs.
6. As a last resort, if there is no natural drainage pattern available, either create one, or turn the excess water into a benefit. Excavate for a small shallow pond, place a liner in it. Add decorative cobbles, rocks, water lilies and other aquatic plants, a fountain, pump, and a filter to keep the water fresh,– and turn it into a beautiful landscaping feature. Correct the drainage of the surrounding area to keep the lawn dry, lush, and healthy.
7. With hardpan subsoil, the lawn can be perforated aggressively by methodical drilling of numerous holes down through the hardpan and filling the holes with free-draining gravel to just below the grass surface. This is an expensive fix and should only be considered an alternative action of last resort. Again, check with local utilities to verify location of gas lines and other superstructure that could be damaged by drilling.
Now that you know how to solve lawn drainage issues, you may no longer need those tall yellow rubber boots to cut the grass.