Golf Committee’s Irrigation Subcommittee Report

February 26, 2009 Meeting

Bob Pleski

Attendees: Don Streseman, Ken Wolford, Ed Lauchner, Tom Watson, Bob Pleski, and Del Price, Guest.

Pipe Breaks

        We are having moderate breaks in the lateral piping and we discussed ways to reduce these breaks. We estimated that if we need to replace the laterals the replacement cost would be about $750,000. This is our estimate of the lateral cost portion of the $1.2M that Knott-Brooks-Linn estimated to replace the mains and laterals.

 Our focus is on reducing breaks in the laterals.

        1. High water pressure in the pipes contributes to the breaks.

        2. Fast shut-off valves in the sprinkler heads contributes to the breaks.

             a. Force = Mass x acceleration/deceleration is a basic law of physics. The shut-off time in seconds is in the denominator and is seconds squared. If the shut-off time is 0.1 second, the force pulling the pipe in the direction the water was flowing is 100 times the force than if the shut-off time were 1 second.

             b. The fast shut-off causes water hammer and the peak pressure of the water hammer adds 100% to 150% on top of the basic line pressure. (Per Chief Engineer of NID).

        3. When we do replace the sprinkler heads, we would prefer heads that operated on the lowest pressure possible to get uniformity with our present head spacing of approximately 63 feet.

        4. It is the committee's recommendation that Ken (Wolford) reduce the pressure out of our Pump Station by 10 psi from 125 nominal to 115 psi. This change will only affect the pressure on the Back 9 because the Front 9 is controlled by the PRValves on the 10th and 18th Fairway.

         5. If air gets injected into the sprinkler lines when the turbine pumps start up, it does not appear to be a problem at this time.

         6. We do have various degrees of hydrophobic soil throughout our golf course. Ken is regularly applying wetting agents to the greens throughout the summer. At this time, only mechanical aeration is used in the fairways.

                 We plan to work with Ken and experiment on different fairway areas on various types of aeration and top dressing.

         7. A number of areas on the Front 9 are lower in pressure, according to our strip chart recorder than the Benbow report indicates. Ken will evaluate this situation.

         8. Bob Pleski will draft a summary report of the findings of this sub-committee to the Golf Committee.