Trenching and Trees

Using an Air Spade excavator to find and protect tree roots when trenching next to large trees


Palm Coast Urban Forester and ISA Ceretifed Arborist, Carol Bennett and the backhoe operator, Santiago, look over the replacement drain pipe that has been installed under the root system of the large live oak. The lateral roots cross over the trench. Notice how nearly all the large lateral roots are close to the surface.

Palm Coast Urban Forester and ISA Ceretifed Arborist, Carol Bennett and the backhoe operator, Santiago, look over the replacement drain pipe that has been installed under the root system of the large live oak. The lateral roots cross over the trench. Notice how nearly all the large lateral roots are close to the surface.

The City of Palm Coast has been a leader in tree protection in north Florida. City staff requires that steps be taken to protect tree roots whenever construction work is being done inside the dripline of trees to be protected. Some of the projects below illustrate the tree-protection procedures using an Air Spade that I have used when working for the City of Palm Coast.

Project: Palm Harbor golf course renovation
Work: Irrigation pipe installation and drain pipe replacement near large 30-inch dbh live oaks (Quercus virginiana)
Location: Palm Coast, Florida
Owner: City of Palm Coast
Course Architect: George Clifton, Clifton, Ezell & Clifton, Deland
When: February, 2009

Installing an irrigation pipe next to three large live oaks

The main irrigation line was planned to pass within the dripline of three large live oak trees. Instead of letting the contractor cut the roots which is normal but bad procedure for the trees, the City required that the roots be preserved over the top of the 5 to 6 foot deep trench. I was hired to locate the roots with an Air Spade and then direct the trench excavation with a backhoe carefully around the roots. The process does not take much additional time once the backhoe operator understands the importance of presrving the tree roots.

 

Initially an Air Spade is used to locate roots near the surface. Then a backhoe is used to carefully remove soil between the larger lateral roots.

Initially an Air Spade is used to locate roots near the surface. Then a backhoe is used to carefully remove soil between the larger lateral roots.

 

The Air Spade and backhoe work together to probe downward looking for more lateral roots that may be 12, 24 or even 36 inches below the surface. Most of the roots are in the upper 18 inches of soil. A skilled backhoe operator can carefully remove soil between lateral roots.

The Air Spade and backhoe work together to probe downward looking for more lateral roots that may be 12, 24 or even 36 inches below the surface. Most of the roots are in the upper 18 inches of soil. A skilled backhoe operator can carefully remove soil between lateral roots.

 

 

 

 

 

 

 

 

 

Hand digging is also needed where the backhoe bucket won’t fit

Hand digging is also needed where the backhoe bucket won’t fit

 

The irrigation pipe is installed beneath the roots.

The irrigation pipe is installed beneath the roots.

 

 

 

 

 

 

 

 

 

Drain Pipe Replacement next to a large live oak

A 30-year old steel drain pipe needed to be replaced. But the pipe ran within 8 feet of a 36-inch dbh live oak tree. Cutting the tree roots is common practice in many parts of Florida but not in the City of Palm Coast. Precautions were taken to locate the major roots and then excavate under the roots to first remove the corroded drain pipe and then insert a replacement pipe into the trench. Work was done with an Air Spade, a backhoe with a skilled operator, and some hand digging from time to time. It is a slow process but one that can help assure the long-term survival of the old trees.

This is the work site before excavation begins next to the tree on the right.

This is the work site before excavation begins next to the tree on the right.

Excavation continues with an Air Spade, hand digging and the backhoe

Excavation continues with an Air Spade, hand digging and the backhoe

A backhoe was needed to remove the old corroded drain pipe

A backhoe was needed to remove the old corroded drain pipe