Thursday, November 5, 2009

Irrigation repair in 10 fairway

A week ago Saturday, we had a major irrigation leak at the start of #10 fairway. The blow out created a hole about 3' deep and about 4' square in our fairway as you can see by the picture below.

Once we dug up the area, the guys had to break concrete from around the tee. The concrete is used as a thrust block which protects the pipes many tees and changes in direction from damage due to the pressure and speed of water that is running through our system. We believe possibly that the weight of the thrust block with the large amounts of rain in October possibly allowed the pipe to pull out of the ductile cast iron tee that you see in the trench.
We replaced the tee and repaired the situation. We will be back filling the hole as the dirt settles and will cover with sod once the hole has completely settled.

From the University of Florida extension service publication CIR1424, there is a good explanation of why thrust blocks are used.

Thrust Blocking
These forces include water under pressure in pipelines exerts thrust forces at tees, elbows, valves, and at any change in pipe size or direction. At times there may be sudden changes in pipeline grade, horizontal alignment of the pipe, or reduction in pipe size. These conditions result in axial thrust and require an anchor or thrust blocks to absorb any axial thrust of the pipeline. Thrust control may also be needed at the end of the pipeline and at in-line control valves. Thrust blocks and anchors must be large enough to withstand the forces that tend to move the pipe. These forces include momentum and pressure as well as forces due to expansion and contraction of pipe.

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