East Texas Timberland Soils – This area has many kinds of upland soils but most are deep, light-colored, acid sands and loams over loamy and clayey subsoils. Deep sands are in scattered areas, and red clays are in areas of “redlands.” Bottomland soils are mostly brown to dark-gray, acid loams and some clays.
— Texas State Historical Association (Texas Almanac)
At Petty’s Irrigation and Landscape, we field numerous calls and requests everyday. Without question, the most frantic and urgent calls we receive have to deal with water issues. Sometimes the call or request is due to a constantly running or leaking irrigation system. For those calls, our irrigation service department responds quickly and efficiently corrects the problem. However, the remaining water related calls we receive deal with poor drainage.
Drainage is one of the most overlooked landscape details in East Texas. Many people are accustomed to sandy soils that allow water to infiltrate and percolate through the soil profile very quickly. Proper drainage is usually not considered until the water begins to rise and encroach on the doorstep or in many cases seep through the foundation and cause damage to flooring and walls.
When drainage problems arise, solutions are abundant and come in a wide variety of shapes and sizes. Unfortunately, many attempts end up wasting a tremendous amount of money because they are not properly implemented or because incorrect assumptions are made in regards to the actual cause of the drainage problem. To properly analyze and diagnose drainage problems, one must consider the soil first and foremost. The soil profile in East Texas can vary widely (especially when considering highly-developed areas where significant grading has been done). The Texas State Historical Association and USDA Natural Resources Conservation Service generally describe East Texas soils in the following manner:
Alfisols (margins of East Texas)
The Duval series is an example of an Alfisol. Alfisols have a subsurface accumulation of clay and have greater than or equal to 35 percent base saturation. Duval soils occur in the Northern and Western Rio Grande Plain on nearly level to gently sloping uplands.
Ultisols (most of East Texas)
The Bowie series is an example of an Ultisol. Ultisols are highly weathered soils that have a subsurface horizon enriched with clay. They have less than 35 percent base saturation. Bowie soils occur in the East Texas Timberlands on broad, very gently sloping to moderately sloping uplands.
— USDA Natural Resources Conservation Service
*Added location descriptions “margins of East Texas and most of East Texas” to the original text.
As you will notice, both sources describe the majority of our soils in East Texas as having a sandy or loamy surface layer with a clayey sub-surface layer. We could spend some time diving in to the specifics of a sandy-clay soil vs. a clay-loam soil, but the main point is that even if we don’t think about it frequently, we must recognize how the sub-surface soils dramatically effect drainage.
For those who truly live on sandy or loamy soils (this includes my house), water does not tend to cause many problems because it doesn’t pond on the surface. However, there are still a few issues to consider:
Common Sandy Soil Drainage Issues:
- Poor grading can lead to accelerated run-off, which may cause erosion or water moving too quickly on the surface to allow for infiltration in to the soil. Poor grading should always be corrected with appropriate grading when possible to create a positive flow of water away from a house or structure. That seems like common sense, but we frequently receive requests to install drain boxes, when grading is the best solution. Retaining walls are another logical choice when dealing with poor grading.
- Limited plant material can lead to substantial erosion, as true sandy soils do not contain any binding agent to prevent the migration of soil particles. With the exception of standing or stagnant water, increasing plant density is always a great first step in dealing with drainage issues as slowing water flow (especially in sandy soils) will reduce erosion and increase soil infiltration.
- Mole tunnels can cause massive sinkholes and erosion as sub-surface drainage gets focused inside the tunnels and erodes the soil from underneath. I have observed entire driveways with absolutely no soil underneath the concrete for six inches because mole tunnels focused drainage in such a way that it eroded the sandy soil underneath the driveway. Erosion due to mole activity is best handled from two directions. First, eliminate the mole activity if possible (there are multiple solutions that claim various levels of success). Second, install French drains to intercept the sub-surface flow of water in the existing tunnels. Keep in mind that eliminating the moles only prevents future tunnel formation, the existing tunnels still pose a threat and thus the need for French drains.
- Allowing the soil level to rise above the foundation is a common problem in East Texas. It usually happens slowly over time and most people never consider the potential problem until they rise from bed in the morning and find themselves standing on a cold, wet, and soggy carpet. Lowering the soil level to fix the grade is one solution, but sometimes not practical. French drains and sump pumps are the other common solutions to water being held at or around the foundation.
Now, for anyone who has to deal with clay soil, you must be more vigilant in correcting and/or preventing drainage issues, as clay is unforgiving in several aspects. Many of the same problems listed above for sandy soil can apply to clay soil, and then there are these unique issues to consider:
Common Clay Soil Drainage Issues:
- Poor grading (it’s a common theme with drainage problems) can be problematic for the same reasons as sandy soil, but then the added complication of having too flat of a grade must be considered. Since clay does not allow for much (if any) infiltration of water in to the soil profile, then proper grading must be achieved to ensure positive flow away from the house or structure. A 2% grade (1 inch of elevation drop per 4 feet of horizontal distance travelled) is the absolute minimum for water to drain off of lawn areas. Even if you achieve a 2% grade, surface run-off will be incredibly slow and you will experience very wet areas during periods of frequent rain or cool temperatures when evaporation doesn’t help. When a proper grade cannot be achieved due to factors outside of your control, catch basins, sump pumps and French drains are possible considerations. Each solution will be site dependent.
- Limited plant material on clay soil can have many of the same effects as listed for sandy soil above. Additionally, exposed clay soil has the complication of allowing for too much soil compaction. Compacted clay soils have a permeability that is closer to concrete than any other soil type. Vegetation, or even mulch cover helps to prevent soil compaction and can even correct compaction issues by encouraging microbial activity that reintroduces oxygen and void spaces in to the soil.
- Allowing the soil level to rise above the foundation in clay soils is a far worse problem than in sandy soils. Many people never even experience a problem in sandy soils as the water still percolates through the soil faster than it can enter the house. In clay soil, the water not only enters the house much easier than it can percolate through the soil, the clay ends up acting as a reservoir of water that will continue to seep in to the house until the water level subsides. The same solutions mentioned for sandy soils are possible in clay, but always remember, clay is not forgiving and the corrective work must be done precisely to ensure functionality.
As you can see, considering the soil is a critical first step that must be taken when analyzing and developing solutions for drainage problems. When you experience drainage problems at your house, make sure you consult experienced professionals to ensure you receive a long-lasting proper solution. We will detail all of the common (and some uncommon) drainage solutions in upcoming blogs as we continue to focus on drainage. In the meantime, if you have a drainage problem, please contact us and we will schedule a consultation at your convenience.