Proper Land Drainage is Important!
Many property owners are not concerned with yard drainage until they have a problem. Water naturally follows the path of least resistance to lower elevations and problems arise when original pathways constructed by the builder become blocked or were inadequate from the beginning. Not having suitable slopes and drains on a property to direct or divert water runoff can allow the water to find a path directly to areas where you would least want it such as foundations, under pavement, in your basement etc. Flooding basements and cracked foundations are good wake-up calls to the issue but addressing problems beforehand can save you thousands of dollars, and headaches, down the road.
The two categories of water supplying a lawn are surface and subsurface. Subsurface water refers to the water below the first layer of topsoil which cannot permeate any lower due to the tightness of the soil beneath. Also known as the water table, all soil has this layer of water with differences in depth depending on the area. Although a high water table can be a problem in some areas, in general, surface water is the cause of excess subsurface water as too much surface water penetrating the ground can raise the water table. Surface water sources are rainfall and irrigation, such as sprinklers, and can be particularly troublesome in urbanized areas which contain numerous impervious surfaces.
Streets, driveways and parking lots simply leave nowhere for rainwater to go. As with a lawn, the runoff will either pool in depressions or flow to soil around the edges causing saturation in another area. When soil reaches 100% saturation, with little or no drainage to assist in excess water removal, not only do pools of water collect, but the saturated soil takes much longer to dry out. This excess water retards plant growth by decreasing aeration in the root zone and decreasing nutrient supplies. Additionally, excess water in the soil will increase freezing damage in the winter months. Having proper drainage on your property will prevent water from collecting around your building or home foundations, minimize soil erosion and help protect your vegetation from death and disease.
Surface and subsurface are the two types of drainage solutions and both are vital protections for buildings and lawns. Surface drainage refers to the natural pathway taken by the water following rain or irrigation and is achieved through gutters, downspouts, surface grates, exposed French drains and by shaping and grading your lawn to provide maximum surface water removal with minimum soil erosion. Subsurface drainage refers to pipes and drains placed in the lawn which remove excess water that has gravitated underground, either through holes in the soil or simply from soil saturation. Water travels through soil by capillary action, which is much like a paper towel – when one side gets wet, moisture will slowly travel to the dry side until the entire substance is saturated. Once the soil is saturated, subsurface French drains are needed to remove excess water. In doing so, subsurface drainage keeps plants healthy, helps soil to warm earlier in the spring and leaves less water to freeze in the winter, minimizing frost heaving damage to your home or building.
Problems associated with improper drainage
Improper drainage can lead to pools of collected water in your lawn and/or around your home or building, both of which pose a threat. When collected close to your foundation, standing water can potentially cause foundation cracks, foundation movement and flooded basements. When collected on your yard, pooling water gives mosquitoes a breeding ground and can leave your grass susceptible to disease.
Foundations: The most costly issue associated with improper drainage is your foundation. Soil naturally expands when it is wet and contracts when it is dry and as long as all the soil underneath your building expands and contracts uniformly, it is not likely to cause a problem. Damage is done, however, when only part of the soil heaves or settles. This differential movement is most often due to differences in soil moisture. Improper drainage on one side of the building can leave wet soil that remains waterlogged for days or weeks (or in worst cases leaves constant water pooled around your foundation walls) while the other side of the structure has soil that dries quickly following a rain.
The wet side has expanded, and remains so, while the other side contracts as it dries, and this action pulls the walls of the structure away from one another. Repetition of this process will eventually produce cracks in the foundations, walls and/or ceilings. Foundation repairs are not usually covered by homeowner’s insurance policies and can cost as much as $20,000 to $30,000 or more to fix, not including cosmetic fixes to drywall, door jams, bricks, flooded carpets, flooring, etc. Anyone who has experienced a flooded basement or cracks due to heaving can attest to a costly fix! In addition, the drainage issues which caused the problem will still need to be addressed.
Basements: The same issue associated with foundations applies to your basement, with the added problem of letting water into your home through the cracks. In addition to damaging carpets, flooring, drywall and furniture, the water increases your basement’s humidity creating the perfect environment for the growth of bacteria and mold. Mold enters your home as tiny spores, which need moisture to grow and multiply. They can grow on almost any surface and they digest and destroy your home as they do. When disturbed, mold spores are released into the air and can be breathed in by you and your family, aggravating allergies and asthma. A small number of molds produce mycotoxins which can induce nausea, fatigue, headaches and lung and eye irritation when a person is exposed to high levels. Furthermore, mites and spiders can proliferate in a moldy basement as mites feed on mold spores and spiders feed on mites.
Waterproofing your basement can help protect your home and is a good insurance policy, but your first line of defense against a wet basement is improving the drainage in the lawn and all areas surrounding the home or building. According to most engineers and home inspectors, 85 to 95% of wet basements and interiors of buildings can be made dry by improving exterior drainage around your house or building.
Mosquitoes: We are all familiar with one of the biggest nuisances of the summer but were you aware that mosquitoes need less than an ounce of water in which to lay their eggs? While standing water is generally the egg-laying site for mosquitoes, some species lay their eggs on damp soil and, if your lawn has poor drainage, leaves your grass as a perfect home for these pests. Needing only two to three days to hatch, your property needs to be able to dry out quickly enough either to prevent females from seeing your yard as a prime location or to dry out eggs that have been laid.
With females laying up to 300 eggs at a time, your yard can easily become infested, driving you and your family inside on warm summer nights. Along with the itching and aggravation of bites, mosquitoes bring diseases such as West Nile Virus, Malaria, Dengue and encephalitis. All are potentially fatal. Your pets are also at risk, as mosquitoes are the hosts for heartworm and can communicate this disease to dogs, cats and other animals. Additionally, West Nile and encephalitis can be transmitted to horses. The American Mosquito Control Association instructs property owners to not only eliminate standing water around your home or building, but to ensure proper drainage on your property to eliminate this potential hazard.
Turf Diseases: As the first impression a visitor or customer has of your home or business, it is no doubt important to you to have well-maintained and inviting landscaping around your property. Death and disease of grass and plants is not only ugly, it is a waste of money invested as well as expensive to correct. Excess water on or in your lawn prohibits the growth of grass, plants and trees by robbing them of their air and nutrient supply and leaving them susceptible to attack by fungi, moss and mold. Fungi, the most common cause of lawn diseases, are microscopic organisms that spread by air- or water-borne spores. The spores act like seeds, sprouting to life and infecting its environment when conditions are right.
Rhizoctonia Yellow Patch, Red Thread, and Pythium Blight are some common fungi diseases which appear in moist environments resulting from extreme soil and surface moisture. Many of the fungi diseases are difficult to control once they appear and damage may remain for two to four years following treatment. While fungicides can be applied to help prevent or control lawn diseases, several strains are resistant to fungicides. The best prevention is the absence of favorable conditions, including improving moisture conditions on top of, and under, your turf.
Mushrooms also need extreme wet conditions to grow. While mushrooms do not harm grass, many of them are poisonous and can be a danger to children and pets that ingest them. Poisonous mushrooms have no features to distinguish them from nonpoisonous mushrooms and identification, therefore, is only possible by those educated about the various genera and species.
Erosion: In addition to the issues associated with standing water, water moving too quickly off your property causes problems as well. As raindrops fall on your lawn, if there is sufficient intensity, the impact will dislodge small particles of soil which can then be carried off by the rain as it flows. This soil will either be carried off to sewers or deposited in another area of your yard, depending on your drainage conditions. Over time, original drainage measures, such as ditches and trenches, can become filled with soil, defeating their purpose and redirecting how water moves on your property. Erosion is accelerated where plant cover is sparse and spaces between plants become larger, leaving no protection for your soil during intense rains. Proper grades and slopes stop water from carrying away your soil by keeping water runoff at an acceptable rate. Slowing down water that is running off too quickly gives soil particles time to settle out of the water and back onto the ground before being transported too far away. Additionally, healthy plant life with deep roots protects and holds on to your soil.
Benefits of proper drainage
Structural Protection: Having a comprehensive drainage system in place protects your structure by preventing water’s damaging contact with concrete. Water that doesn’t evaporate and isn’t absorbed by soil eventually goes somewhere and, oftentimes, it sits under and around your foundations. Drainage solutions will keep the moisture content around your foundation stable and uniform, keeping contraction and expansion to a minimum. This maintains the integrity of foundations and helps prevent cracks and water seepage.
Plants and Landscaping: Proper soil moisture is essential for plants and lawns to establish a healthy root system. Removal of excess water in the soil deepens the root zone and increases the air in that area. The increased aeration, in turn, increases the supply of nutrients, many of which need the air to convert chemically before they are accessible to plants. The deep root system which grows will then holds on to the soil and protect it from erosion. Additionally, water will not pool in areas of your property, leaving turf susceptible to disease, and help you maintain the pleasing aesthetics in which you invested.
Recreational Areas: By implementing drainage solutions, recreational areas, such as parks, golf courses and athletic fields, improve traffic ability and increased use of the property. Drains help nature clear out excess water and allow turf to quickly recover from rain. The result is that the recreational area can be open for extended periods of time and for more intensive use, resulting in increased revenue.
Spring showers are not the only cause for concern
The Midwest is notorious for extreme weather changes with a drought one year and floods the next. While St. Louis has an average rainfall around 40 inches, in 2008 we had 50.72 inches pour down on us, with nearly half of that amount coming between June and September. If you have weathered winter snow and spring rains, do not let down your guard thinking you are safe for another year. Summer can sometimes bring surprises and the added deluge to your soil will only intensify existing problems requiring more extensive repairs.
A note about water tables
Water table refers to the depth at which the soil always contains 100% water. In some areas the water table is higher than the bottom of the foundation, requiring a complex system of drains and sump pumps to draw the water away from your structure. High water tables can lead to devastating damage to your foundation or basement and is sometimes cited by professional waterproofers as the cause of a problem because of the expensive measures to correct it. The National Association of Home Builders, however, estimates that only five percent of wet basements are due to high water tables. If you have water damage, you are most likely dealing with surface runoff problems which can be corrected through slopes, grades and drains in your yard, along with proper gutter systems. Modern building codes prevent contractors from building basements where water tables are high and if your home or building is less than 30 years old you can be reasonably sure a high water table is not your problem. If you have a wet basement, be aware of this issue! Inform yourself by contacting your local building inspector and getting information about your local water table.
Do you have drainage problems?
Try this experiment: dig a hole one foot across and two feet deep and fill it completely with water during a dry spell. If the hole drains completely in less than five minutes or in more than 15 minutes, you have a problem. A more simple way to spot problems is to look at your lawn during and following a rain. If you have water flowing quickly across the yard removing topsoil during a rain or pools of water on driveways, parking lots or lawns following rain, then you have a problem. Other indicators include yellowing plants, yellowing or thin turf although it receives plenty of sunlight and has no obvious disease, fungus or mold on the lawn, stagnate water smell and water seeping through door sills, basements and garages.
Types of drainage solutions
A comprehensive drainage system will include surface and subsurface drain solutions. Surface drains remove the large amounts of water that fall in short periods of time and subsurface drains remove the excess water absorbed into the soil. The two systems work in conjunction to maintain the moisture in your soil at the proper level for protection of your landscaping and your home or building.
Gutters: Your first line of defense against foundation flooding is your gutters! During a moderate rainfall, the average sized roof sheds 160 gallons of water runoff per hour. To prevent the runoff from being deposited on the ground next to your foundation, a proper gutter system is essential. Not only is the correct gutter size for your roof area a consideration, but an insufficient number of downspouts is equivalent to having no gutter system at all. Downspouts are needed to handle the volume of runoff your roof will collect and splash blocks must be utilized to direct the runoff away from your home or building and out to your drain system. A better solution to splash blocks, however, is to install PVC piping to the end of the downspouts to remove the water 6-10 feet or more away from your home or building. Furthermore, gutters must be properly maintained to prevent clogs and gutter joints must be inspected for leaks. Having a suitable, effective gutter system should be the first step in your drainage solution.
Grades: To protect structures, the most important grades on your property are those within 10 feet of your foundation or basement. This will prevent the water you just diverted away from the structure from soaking back through the soil toward your structure. Suitable grades vary depending on who you consult but a safe measurement is a 1 inch (or more) drop for every 1 foot out for the first 10 feet. This results in at least a 10 inch slope for the 10 feet closest to your foundation walls. The rest of your yard should contain a continuous slope downward to keep the water moving away from your foundation.
Surface Drains: Surface drainage can be defined as the controlled removal of water that collects on the land from rainfall, irrigation, snowmelt or hillside seeps. As gravity is the primary force driving this type of system, it involves shaping the land with a continuous fall in the ground level to provide a downhill passage for surface runoff at an appropriate rate of flow. For grass drainage channels, or swales, a minimum slope of 1% to 5% is desired. The contours of the land then direct the runoff to a suitable collection site, such as ditches, basins or storm sewers. At the low point of the ditch or interception point, area drains are installed which are connected to a main or submain and prevents the water from pooling in your yard. The underground pipes need a minimum slope of 1% or 1/8 inch per foot to keep water moving through them. If the ditch is long, several smaller drains should be spaced in a series, rather than one large drain in the middle, to help prevent erosion.
For driveways and other hardscapes, channel drains and exposed French drains are ideal. These linear trenches collect sheets of water that run off, as concrete and asphalt absorb none of the water as it falls. The open area of the channel/ exposed French drain is much greater than an area drain and is better suited to the greater volume of rain it will need to collect. Additionally, channel drains allow designers to modestly slope hardscapes, rather than requiring numerous, extreme slopes to direct runoff to area drains.
Subsurface Drains: While the benefits of subsurface drainage are hard to see because they occur within the soil, the difference will be noticeable in your plants, grass and soil. Subsurface drainage is the removal of gravitational water from the soil, which is accomplished by placing French drains underground to collect and remove water to a drainage outlet. Subsurface drains do not remove water necessary for plants, only excess water, which flows to the drains by gravity. Sub-Surface French drains consist excavating a sizable trench and lining it with a filter or geotextile fabric, which helps prevent soil particles from entering the French drain. The trench is then filled with clean rock/gravel and a proper sized perforated PVC pipe for the application is placed in the gravel.
Once the trench is filled with grave, it will be covered with a layer a permeable filter fabric, installing a mixture of high quality topsoil/ sand and lastly installing new sod on top (assuming this French drain will be located in a grassy area). French drains function when water in the soil enters the gravel bed, flows into the perforated pipe and travels through connecting solid pipes to a discharge point. A general guideline for placing French drains is to use 4 – 6 inch perforated pipes, bury them 18 to 36 inches deep and space them 15 to 20 feet apart. In the trenches, pipes must maintain a .1% to a 1% slope. Soil construct, acreage and turf usage, however, may require variation from these guidelines and a professional can help you determine the best solution for your situation.
Discharge Outlets: Once water is collected in the pipes, it must be diverted to a suitable outlet to be released. This outlet can be a street gutter, a storm sewer or an onsite pond. Using a pop-up drainage emitter, water can be diverted to a water-safe area on your property away from your home or building. Pop-up drainage emitters are opened by the hydrostatic pressure of water flowing through the drain pipe, releasing water collected from gutters, downspouts, basins, grates, etc. If placed close to the street, the released water can flow over the curb and into the street without having to drill through the curb. The emitters then close as water flow diminishes, preventing debris and animals from entering the end of the pipe and clogging the system. Property owner or maintenance personnel need to make sure they perform routine maintenance on the pop-up emitters. This can be done by removing the pop-up to make sure there is no debris washed down from the roof gutters or surface drains that could potentially slow down the water flow in a heavy rainfall event.
Cleanout Connections: It is a good idea to install cleanout connections on all drainage systems integrated into your property. This is commonly overlooked until pipes need to be accessed by cameras or cleaning equipment years after the initial installation. Access points are needed for the following three reasons. 1) Routine maintenance, and especially if routine maintenance is neglected because the contractor will have to access the pipe to unclog them for a fee of course. 2) If the systems functionality has declined. 3) If damage has occurred to the drainage system pipes from heavy equipment or excavation during an on-site construction project. Although cleanouts add cost to your project, it is highly recommended to have cleanouts installed on all downspout connections, all French drain systems and all long mainline pipe runs over 80′ without drain grates in which you can access.
Before contracting to have you project installed, make sure cleanouts are integrated into your drainage system. It has been calculated that the cost to cut into a pipe and then patch it because there are no cleanouts will be a minimum of twice the cost as having them installed in the first place. Sometimes it is 5-10 times as much when access is needed to an existing French drain without cleanout connections. So don’t gamble because when you’re installing a system with materials that last decades, you undoubtedly will need access; if for nothing else, routine maintenance. A professional drainage contractor should be able to help you determine the best cleanout points for the system their proposing for your property.
Finding & Hiring a qualified drainage contractor
Doing your homework on potential drainage installers is important. You need to be assured that your contractor is insured and has the skills needed to properly install your systems. Be wary of “special deals” or the “great deal from a friend of a friend” – these will most likely cost you more dollars and headaches in the long run.
Tools for Locating a Potential Drainage Contractor: The Better Business Bureau is a great starting point in your search for a contractor. They maintain an online directory for BBB-accredited businesses in your area. You can check not only how long a contractor has been in business, but also any complaints filed about their operation. Angie’s List is another great tool for recommendations, as you can get testimonials from actual customers. Even if you “hear of a guy from a friend,” check their references online. See what other people’s experiences have been and choose a pool of potential contractors from the best you can find.
Portfolio and References: After you have a list of potential people for the job, ask to see a portfolio of their previous jobs and whether you can see former worksites. If possible, see their handiwork in person, perhaps driving by a home or business during or after a rain. This will help you not only to understand their drainage plans for your property, but to assure you they can indeed get the job done right. If you can speak with former customers, ask if they were satisfied with the work, whether the contractor stayed within budget and if the project was completed in a timely manner. You need to look for the best person for the job, not the lowest bid. You want the problem to be fixed upon project completion; you do not want to be dealing with drainage problems or, in worst case scenarios, legal problems, long after the contractor has left.
Bids: Get at least two bids for your specific job and get them in writing. Furthermore, make sure you understand the difference between the bids. Higher bids do not always mean a contractor is trying to get more money into his pocket. Better materials, more skilled workmanship and better reliability may be worth a slightly higher price. Keep in mind that, usually, you “get what you pay for.”
Insurance: An important issue when hiring a contractor is his insurance. If your contractor does not carry general liability insurance or worker’s compensation, the property owner can held responsible for any accidents which occur while work is being done. To protect yourself, ask for proof of insurance. Reputable contractors will understand that you are doing your research and will not be offended. Be wary of any that try to convince you this is unnecessary – they may have something to hide.
Skills Needed: Make sure potential contractors have the skills needed to do your job. Is your contractor a drainage specialist or merely a landscaper who has dabbled in drainage installation? Can he utilize a transit to analyze your slopes if needed? Does he know the proper depths and spacing for pipe placement in your yard? Most importantly, is he diverting your excess water to a suitable outlet? Purposefully diverting water to a neighbor’s yard, when runoff didn’t already naturally flow to that yard, can result in huge fines. As the property owner, you will be held responsible for your contractor’s end result.
Equipment, Supervision & Project Site Management: Find out who will supervise the work and how often will they be onsite to see that the plans are followed? Will the project continue daily until finished without interruption other than weather delays? You need to know who to call if you have a question or problem. Furthermore, does your contractor have access to the equipment needed to get the job done?
Products: Which products does the contractor use and are they the best in the industry? Be wary of contractors that offer a big discount because they will use materials left over from a previous job. While you may be interested in saving a few bucks, are you certain these materials are suitable for you project and needs? Having the project done with substandard materials that will not last never ends well for the property owner. You might have to have the system torn up and reinstalled a couple years later, costing you double down the road.
Warranty: Make sure there is some sort of a warranty with your drainage system installation once it is complete. More importantly feel confident enough with the company that they will even be in business to fulfill that warranty agreement. See if they can give you a past customer that you can call to talk to where they had a warranty issue that the contractor successfully resolved for them. Many specialized drainage companies offer a minimum of a 12-month warranty of full functionality, some contractors offer more.
Warning: We know of a family who hired a contractor that a friend’s neighbor had used. Although they met with him and thought he seemed like a “good guy,” they did no research on him or his business and references were not checked. After realizing that no real progress had been made in spite of the thousands of dollars they had paid him, they began to investigate. As it turns out, the friend’s neighbor had had similar complaints and was dissatisfied. If the homeowners had spoken to the people for whom the contractor had worked, rather than going by their impression of his personality, they would have been spared a good chunk of change. In addition to leaving their home a complete mess, they lost all the money initially invested and had to pay someone else to finish the job. Furthermore, because they had not done their due diligence regarding the contract, they had little legal recourse. The lesson: always err on the side of caution! Do not assume that a contractor has your best interests at heart; look at their previous jobs and, if possible, consult people for whom they have worked. Most people are happy to tell you about their experiences with a business, whether good or bad, and businesses with a solid reputation are not wary of you seeing their previous work.
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