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

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.

Palm Coast Urban Forester Carol Bennett and backhoe operator Santiago view the installed drain pipe and saved roots before backfilling the trench

Palm Coast Urban Forester, 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.

 

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

 

 

 

 

Roots exposed by Air Spade

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.

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 excavation with a backhoe.

 

backhoe helps remove soil between large lateral surface 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. A skilled backhoe operator can carefully remove soil between lateral roots.

 

 

 

 

 

 

 

 

 

 

hand digging is also needed

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

 

 

 

 

 

 

 

 

 

irrigation pipe installed under the lateral roots

The irrigation pipe is installed beneath the roots.

 

 

 

 

 

 

 

 


Drain Pipe Replacement next to an old live oak tree

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

the work site before excavation begins

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

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.

 

 

 

 

excavation begins locating surface roots

First surface roots are located with an Air Spade.

 

 

 

 

 

 

 

the old rusted pipe is removed from the trench with a backhoe. Notice the tree roots extending across the top of the trench.

A backhoe was needed to remove the old corroded drain pipe

 

 

Once the roots have been located with an Air Spade the trench is enlarged with both an Air Spade and a backhoe.

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

 

 

 

 

 

 

 

 

 

 

inserting the new pipe underneath the tree roots

The new drainpipe is inserted beneath the roots.

 

 

 

 

 

 

 

 

 

 

 

 

 

Project: blocked drain pipe replacement
Location: Palm Coast, Florida
Contractor: City of Palm Coast
When: Summer, 2006
Tree: 20 DBH live oak (Quercus virginiana)
The assignment: remove an old blocked drain pipe that had been installed over 20 years ago adjacent to a live oak tree.

We used an Air Spade to

excavation with Air Spade and backhoe beneath roots

This old corroded drain pipe had to be carefully removed without disturbing the roots of the adjacent live oak.

locate roots that passed over the drain pipe. A backhoe was used to carefully remove soil from areas where no roots were found. The old pipe was carefully pulled out from under the roots and a new black poly pipe was slipped beneath the roots. Soil was replaced into the trench over the existing roots. The tree was irrigated regularly for the rest of the summer. And now the tree is doing fine and a new drain pipe is keeping the neighborhood from flooding. The tree was much smaller when the initial trench was dug and the original drain pipe installed about 20 years ago. The number and size of roots that have grown back across the trench are surprisingly few and small. I have found that once a significant number of roots have been severed, they do not grow back in the same quantities. Most likely the tree grew new roots in

the new pipe installed beneath the roots

The new drain pipe has been installed beneath the roots

other areas away from the trench.