Outdoor Drainage Solutions

According to the Minnesota Residential building code, grading against the homes foundation should drop a minimum of 6 inches within the first 10 feet away from the foundation. 

If Ideal Foundation Grading is Not Possible - We Have Other Solutions

What is a Drainage Swale? 

A swale is a shallow graded channel with gently sloping sides used to drain water away from a source location.  In residential areas, swales are typically designed to send the water they collect into either the city storm water system (the street) or a drainage easement along the lot line.  Swales are also commonly designed to empty into other drainage systems/areas such as rain gardens, dry wells or wetlands.  First, good foundation grading gets water safely away from the house, then swales are used to send that water even further away to its final destination, e.g., the street.  For a MN outdoor drainage contractor, a swale is one of the most common and reliable grading for drainage methods used to manage water within and between yards.

Drainage Swale Design Considerations

• Minimum Slope Required:  A swale should be constructed with no less than 2% slope (minimum of ¼” per foot drop in elevation) to ensure water can drain properly through the swale. 

• Lot Line Swales:  For typical residential lots, swales are used along property lines in the side and/or backyard to collect and drain storm water runoff between properties.  In many places, water is designed to drain to the lot line swale along the far back of a backyard and which drains water from many neighboring properties.  These types of swales are very often designated as drainage easements by city code to prevent people from blocking the flow of water within those swales. 

• Internal Swales:  Swales that are installed within the boundaries of a property rather than along the property lines are referred to as internal swales.  Internal swales are often used as a drainage solution in flat yards or yards where negative grading exists (e.g., hills or sloped areas that angle toward the house) that without a swale would be sending water directly toward the house. 



• French drains are best used to remove water from oversaturated yard spaces when is it not feasible to achieve adequate drainage by just adding the proper slope to the grading in those areas.

How Does a French Drain Work?

What is a dry well?  A dry well is an underground water collection, storage and infiltration system used in landscaping.  Dry wells give water draining from adjacent landscaped spaces somewhere to collect and hold while waiting to permeate the soil below.  Dry-wells are most often used as a drainage solution for the lowest lying area in the yard, when there's nowhere else that water can be send via drain tile to discharge.  Dry wells are also commonly used as components of driveway, pool deck and paver patio drainage solutions in Minnesota.  Dry well systems can be designed to include a pump, commonly referred to as an outdoor sump pumps, which vastly increases the volume of water that can be controlled by a dry well system.   

Dry Wells Can be Used as Drainage Solutions For:

• Winter Thaw / Spring Melt Drainage:   Dry wells that are installed to a depth of at least 48" reach down below the frost line and have the ability to drain melting snow effectively during the spring melt, when many other yard drainage systems are prone to freezing up.  This is because water in a dry well system can drain down through unfrozen ground at the bottom of the dry well.  Dry wells are one of the best options for winter and spring drainage in Minnesota.

• Drainage in Flat Yards: In landscape spaces that have no slope, not enough grade or even a negative slope running back toward the house; a dry well can be used to give water a place to drain, when no alternative drainage outlets exist.

• Water Pooling in Backyard:  A dry well can also be used as a water permeation solution for an existing low spot in the lawn that gets soggy, floods out or doesn’t dry out quickly enough to be functional.  Installing a dry well increases the total volume of water that can be quickly drained away from the house and into the landscape, which helps prevent water from pooling, ponding up and running back toward the house.

• Driveway Drainage for Tuck Under Garages: dry wells are often used as part of channel drain or catch basin drainage systems for flat driveways or negatively sloped driveways built for tuck under garages.  In these situations the channel drain collects water that would otherwise run directly into the garage.  When the location of the driveway drain is the lowest elevation on the property, a dry-well is needed to give the water collected by the driveway drain somewhere to discharge.  These driveway dry well systems are typically installed below the driveway itself and built to a depth below the frost line to improve winter drainage and prevent freezing issues.
  

Catch Basin Drains for the Yard

Catch basins can be installed in lawn and landscaped spaces to prevent pooling or wet / muddy spots in the yard.  Simply adding a catch basin can be great idea in circumstances where is doesn’t make sense to regrade a large section of a yard just to drain one specific problem area.  Catch basins can also be added to French drain systems to help drain water more quickly into the French drain.  In certain situations, adding one or more catch basins to a French drain system is ideal to help collect surface water directly into the French, rather than only being able to collect that water after it works its way down into the soil profile.

In Landscaping, drain tile is used to remove water from poorly drained yard spaces where oversaturated soils can cause problems.  Some of the common outdoor drainage problems that outdoor drain tile can help solve, include: water getting into the basement, a sump pump running too often, pooling water in the yard, wet/soggy lawns and frost heaving issues below patios, deck footing and around the house. 

Exterior drain tile most often used as a solution in landscape spaces that where ideal grading is just not possible.  Poorly drained clays soils are also a very common factor in situations where outdoor drain tile systems are needed.

Underground  Downspout / Gutter Extensions

Underground downspout extensions can send rainwater from the gutter system far away from the home’s foundation without the unsightliness or tripping hazard of a long above ground downspout extension.  In addition to a clean look and helping keep your basement dry, underground downspout systems can prevent the discharging of water into other undesirable locations, such as preventing a downspout from dumping water into an already soggy lawn area or from dripping onto a sidewalk causing ice problems in the winter/spring.

Although the concept of installing underground pipe sounds fairly simple, in fact there are many design details that go into building effective and durable underground downspout extensions in Minneapolis and St. Paul.  This is especially true because of the challenges we face when it comes winter and ground freezing issues.  Learn much more about underground downspout drainage systems by checking out our blog:  How to Prevent Freezing, Blockages & Breaks in Underground Downspout Drainage Systems

At KG Landscape, we know how to build underground down spout extension systems the right way and can help you decide if they are the right solution for you.