Drainage for Florida homes and soils: clay below your home

Florida homeowners often experience yard and property flooding. Heavy rains saturate the ground quickly, the rain water cannot percolate into the earth fast enough to prevent rising or flowing water. Florida homes are built on many types of soil unique to Florida. As everyone knows Florida soils can be very sandy. People don’t realize that Florida soils can contain significant clay layers. Many homes are built on these clay layers. Some are thin, some are very thick. Clay acts like a layer of plastic in the soil below your home, yard, driveway, parking lot etc. Depending on the consistence and thickness, the clay will stop water from percolating. Clay prevents water from being absorbed into the earth, therefore the soils in your yard or property remain wet for day, weeks or even months after heavy rains. Water will sit on top of this clay and move horizontally. It will even move (flow) under your home and try to absorb into and thru your concrete slab, entering your home in the process. This water can cause significant problems with interior moisture and structural damage.

We have seen water pooling under floor tile, soaking into and warping wood floors and ruining carpets inside homes. In one case water was seeping up thru the dining room floor tile in the middle of the house. All of this caused by clay in the soils, underground in the yard and under the home.

Southern Drainage Systems recently installed a drainage system in June 2018, for a homeowner who had flooding along the left side of their home. Water would flow over the pool deck, into the pool and nearly into the home. We found a thick, clay layer below the ground in this subdivision of homes in the Safety Harbor and the Palm Harbor area of Pinellas County Florida. Surprisingly, many homes in the Tampa Bay and Pinellas County area have a clay layer below the home and yard.

Two types of Drainage System designs are often used to solve flooding property or to stop water from entering a building or home.

1. Catch Basin System – Catches the water with a basin set level with or slightly below the surrounding ground. Setting the basin correctly often requires a laser or transit to determine surrounding ground elevation. The pipe attached to the basin must also be set with a laser or transit. Guessing or eyeballing the elevation wont work.

2.  French Drain System – Catches the water both surface water and subsurface water. Pipe with holes allows water to enter the pipe and flow to an outlet. French drains must also be set with a laser or transit accurately to ensure perfect downhill slope. French drain systems often fail due to roots growing into and entering the pipe thru the holes. Southern Drainage Systems LLC uses a special fabric that surrounds the French drain pipe and prevents roots from entering. The deters the roots from growing in that direction. Our drainage systems are designed to last over 20 years.

Southern Drainage Systems LLC completed a drainage system in Carrollwood, Tampa FL. in January 2018. This beautiful residence had been flooding for decades. The previous owner installed a sump pump which did not work properly. The yard would stay saturated making the yard a muddy mess, preventing the kids from playing in the yard. Water would flow from the back yard, underground into the road for weeks after a normal summer rain and the yard would stayed flooded. 10″ deep water in the back yard thru most of the rainy summer months. Southern Drainage Systems LLC designed and installed a combination catch basin and French drain system for the homeowners who had been enduring the flooding for three years. The drainage system captured all roof water, downspouts, and pool deck drains. A catch basin system was installed on the left side of the house. A combination catch basin, French drain system was installed on the right side of the house. The right side system required a R.O.W ( right of way) permit. The City of Tampa issued a R.O.W. permit to install pipe under the sidewalk to the road. Southern Drainage Systems designed, constructed and installed a traffic rated, concrete outlet, which was installed along the road edge. This system has been installed and operational since January 2018. The homeowner has reported the kids can play in the yard after the rain stops and no flooding anywhere in the yard since the system was installed.

The soils in Pinellas and Hillsborough County vary significantly. Homes in Seminole FL. have dense limestone rock in the yards along with clay. Installing a drainage system in this area requires breaking and removing rock to set pipe at the proper elevation. Safety Harbor homes are often built on thick layers of clay. Southern Drainage Systems has installed over 2000 ft. of drainage pipe in homes located in Safety Harbor. Every home had layers of clay beneath the home and in the yard. Water settles on the clay and it becomes similar to Play Dough. Water wont pass thru it. Areas of Palm Harbor have extremely thick, sticky clay. This type of clay sticks to shovels, trenchers, and makes digging very difficult and time consuming. Some areas in Carrollwood Tampa have a soil type known as Smyrna fine sand. These sand grains are extremely fine. Hand digging can require a pick or mattock also know as a pick axe. Even a trencher will bounce when digging thru these dense soils.

Drainage problems often occur when the ground elevation forms a low spot. If the ground is very sandy, water should percolate quickly, but Florida rain storms can produce 2″ to over 6″ of water in an hour. Proper grading during construction is necessary to prevent drainage concerns. The ground elevation does change over time, changing the direction water flows. A Home in Tarpon Springs FL. required a drainage system to prevent water from flowing down hill, filling a low area and flooding the pool deck. This yard had sandy soils which percolated very quickly.

When purchasing or building a home, have the soils checked for clay. You can simply dig or hire someone to dig a small hole down 24 inches. Normally you will reach clay within 2 ft. You can also have a knowledgeable drainage professional check the soils for clay. Clay is very distinct. The colors are often turquoise green, gray, off white, or combination of colors. Clay is sticky when wet.