Of all the elements and processes associated with designing, installing and maintaining a quality landscape, none is more important than proper drainage!
Maintaining the approved/certified grade that came with your home or business at closing or developing the proper grade to ensure that water moves in a positive fashion away from structures and other features should be the very first item reviewed during an initial site visit.
Professional excavating “marking whiskers” ( please see... http://www.acpinternational.com/marking-whiskers.html ) are often used to mark and maintain an approved grade during and after the properties development process. They should remain in place and kept visible to ensure that the approved grade has been maintained. Should they become covered during the course of landscaping your property, it is a simple matter to re-expose them as your landscape installation continues. Ideally, they would remain in place even after the final sod or mulch has been placed. Following this guideline, there is visible and supported proof that the approved grade has not been changed.
Where possible, it is excellent to have a 10% or greater fall away from your home or buildings foundation. At 10%, that would mean that from the structures exposed foundation the soil would fall 12 inches or 1 foot in 10 feet. Such a slope/grade however would be a bit difficult to navigate comfortably.
While a 10% slope/grade would appear to create a problem should you desire to install an access pathway all is not lost. At the bottom of the slope/grade (the area furthest away from the structures foundation) some form of retainage can be utilized. The void between the slope/grade and the retainage can be backfilled with a highly permeable product such as the many forms of clean (no small paricles referred to as “fines”) stone mulch. If desired or recommended, a drain system can be incorporated to permit water to drain even more efficiently. The slope/grade as well as the drain system will not be visible and you will be left with a far more level surface on which to walk or install some form of hard surface such as natural stone stepping stones. Please note that if a concrete pathway is desired, special caissons and bridging may be required to reduce the risk of concrete movement while still permitting proper drainage.
But what about your home that has been in existence for decades without issue...? You now face the anguish of a flooded basement and stagnant pooled water in crawl space with the relentless headaches involved with returning your home back to normal...? Have hope, there are solutions!
A site visit by a reputable landscape professional will determine where the problems may be stemming from and possible options available to correct the concern.
The following are some of the more typical drainage concerns we come across routinely...Do any of these sound familiar...?
*Problem: Does the slope/grade around the home maintain a positive (away from the foundation) or negative slope (towards the foundation)...?
*Solution: Remove some or all of the landscaping and apply appropriate regrading techniques. Please note that the use of special water proofing products such as waterproof membranes and tar like products may be helpful, their use should be carefully reviewed and are best advised in conjunction with proper grading and the use of special drain systems
*Problem: Does water come in over the top of the window well or at the juncture where it meets the structures foundation...?
*Solution: Install window well extensions followed by regrading appropriately
*Problem: Do window wells have enough permeable backfill so as to allow ample time during a storm before water rises so high as to enter the structure...?
*Solution: Excavate window wells to a depth of 3 feet, line with porous landscape fabric and backfill with clean crushed recycled concrete
*Problem: Are all downspouts and/or sump pump drains discharging properly to drainage swales (shallow depressions) that will then permit water to continue on its way away from the home and/or property...?
*Solution: Be sure to routinely clean gutters and downspouts to ensure their proper operation. Confirm that there truly is an escape route for the water once it has exited the downspout and it (the water) will not simply flow back towards the foundation in an endless cycle.
*Problem: Do hardscape features such as patios and walkways slope away form the home or have they settled creating a negative drainage scenario (water drains back towards the home)...?
*Solution: Review whether full replacement is required or can the patio or walkway be “lifted” back to its original position through either mud (concrete) or foam jacking.
*Problem: Have landscape elements such as trees, shrubs grown in size and their root flare (the area where the trunk meets the ground) created an obstacle whereas the water cannot move around it appropriately...?
*Solution: Create a new drainage solution around the obstacle or as a last resort, remove the plant and be sure that the stump is taken down below grade far enough in order to permit adequate water flow away from the home.
Problem: Through time have your landscape beds increased in height through the addition of excess organic mulch or soil...
*Solution: Rake out and assess the grade beneath the mulch to determine if simply disposing of the excess mulch will permit proper drainage or whether regrading will be necessary. Typically, a 2-3” layer of organic mulch is adequate for trees, shrubs and the majority of perennial flowers and ground covers. Annual flowers require far less. As a side note, the newer more plant friendly landscape fabric help retain moisture with older style fabrics or at worst plastic sheeting contributing dramatically to both poor plant health as well as excess moisture retention. Please see these links for more information...
*Problem: Are retaining walls or landscape edging creating a damming effect thus not permitting water to escape appropriately...?
*Solution: Retaining walls should be constructed according to manufacturers specifications. Any retainage requires adequate drainage behind the wall to relieve the negative effects of water build up behind the wall called hydrostatic pressure. An inspection should determine if the wall is properly drained and if not, how to most cost effectively remedy the problem. Landscape edging can have notches cut to relieve the water backup or edging with holes manufactured into the edging itself switched out with the problematic sections. An option when using organic mulch is to alleviate the formal edging altogether and simply use a natural spade cut edge...Please see these links for more information...
Where neighborhoods, properties and buildings have evolved through time and do not currently have an easy way to get water to leave the property, the use of special drainage systems and drywells can be considered. It is very important to understand that the use of a drywell is for the short term capturing and storage of storm water until it can naturally leach into the surrounding soils. It is not intended for long term storage and reuse of such storm water.
Drywells are best located as far away from the structure as budget will allow and sized appropriately for the area and other elements contributing to the water that will enter the drywell. Drywells when placed far enough from the structure can be permitted to 'overflow” once full with the excess water migrating off the property or simply saturating a larger diameter than the drywell area itself.
Where possible, it is best to create drywells where a stone covering/mulch can be utilized versus sod or organic mulch. Drywells can contribute to soft wet zones when full of water and very dry spots in the landscape when drained down substantially. A large round dried out section of lawn is just as unappealing as a squishy, deeply rutted lawn area complete with muddy mower wheel tracks!
The use of specialized drainage pipes and other permeable materials often times referred to as French drains may be appropriate in solving your drainage issues. Such systems are especially helpful where having moisture travel below grade (surface) will then permit surface activities such as children's play or simply clean and dry foot traffic.
Proactively reviewing and resolving your landscapes current drainage conditions is far less stressful than the morning after your basement flooded and your insurance company relays their bad news! Once you have the knowledge of what issues are present and how to resolve them, you can often times proceed at a more controlled and methodical pace in correcting them. There is nothing worse than just getting the water all bailed out of the basement, having the fans turned on high attempting to dry the carpet before mold sets in and the Weatherman comes on informing you that tonight’s storm will be even heavier than last nights!
Digging drainage ditches and placing sandbags in the middle of a rainstorm is not only stressful but very dangerous when the threat of lighting persists...especially in Colorado!
But for those who relish living life on the brink of danger, suspense and the unknown, resolving your drainage issues can by all means wait...After all, that torrential rainstorm the Weatherman keeps talking about may only turn out to be a light sprinkle! But just in case, you may wish to view the attached link and consider its content as one adventuresome option!