- Roof leaders or down spouts that direct rainwater on to the lawn. Roofs collect an unbelievable amount of water.
- Surface grading that is sloped toward a walkway or house foundation. The impermeable surface of a walkway or foundation acts as a dam, preventing any flow in that direction and can result in ponding.
- Adjacent properties that have been raised, draining water to lower areas surrounding, 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.)
- Poor quality, uneven grading that has major depressions, which are potential collection points for water in the center. Water always collects in the lowest areas.
- Hardpan subsoil. Hard clays and hardpan are impermeable to water and prevent surface water from percolating into the ground. Hardpan soils disguised by a thin layer of topsoil can be as little as a few inches thick, or many feet thick.
All physical conditions should be carefully identified prior to taking remedial action. Once you have determined why water remains on the grass, the most significant source of the problem can be addressed and solved. Here are a few thoughts on solving drainage issues.Roof leaders, gutters and down spouts: Roof leaders and downspouts handle a very large amount of water which must be directed away from the foundation of the building. Most down spouts have a little bend at the bottom end, which merely shoots the water a foot or two away from the wall, but it also directs the water onto the nearest lawn, where it will collect if there is inadequate drainage. Extend the down spout to direct water to a swale. *Note that in most jurisdictions, it is illegal to connect roof leaders to the sanitary sewage system, which overloads sewage treatment plants and control systems. Surface Grading 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. 2. If water is collecting along a walkway, or foundation, consider correcting the grade just enough to allow the water to drain away from any foundation, and allow drainage from one end. 3. If your lawn surface is lower than an adjacent property and collecting water from that 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. Instead, allow for a drainage swale between the properties. In this instance, a good drainage swale creates good neighbour relations. Perhaps raising 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, puddle-prone area of the lawn to provide permanent drainage. Locate a discharge point that will not be problematic. See "How to build a French drain". *Do check with local utilities to verify location of pipes, gas lines, or wires prior to any excavation to avoid unnecessary damage and expense. 6. As a last resort, if there is no drainage pattern available, turn excess water into a benefit. Excavate for a small pond, place a liner in it, add decorative cobbles, rocks, aquatic plants, a fountain, pump, and a filter to keep the water fresh, and turn it into a beautiful landscaping feature. Correct the balance of the drainage area to keep the surrounding lawn dry, lush, and healthy. 7. With hardpan subsoil, the lawn can be perforated by methodical drilling of numerous holes down through the hardpan layer 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 locations of superstructure that could be damaged by drilling.
8. Evaluate drainage issues over two or more wet seasons to ensure adequate drainage is created. Correct any inadequacies as they are discovered.
Hopefully, now that you know how to solve lawn drainage issues, you will no longer need rubber boots to cut the grass.
Is that Incoming I hear?
photo credit: Wikimedia Commons