The Knott-Brooks-Linn master plan for the golf course recommended that LWW start setting aside $1.2M to eventually replace the underground piping. When a number of golfers questioned the need for this expenditure, the Golf Committee created the Golf Irrigation Subcommittee at the October 2007 meeting.
TASK
A. To ensure that the operation of the irrigation system will result in the maximum life possible of the pipe and fittings.
B. To get the maximum uniformity of watering on the golf course.
PROCEDURE:
A. Collect data on how many breaks occur.
B. Measure the uniformity of watering with the present Rainbird heads, Model #700.
C. Analyze the above data.
D. Before buying new heads, measure the water distribution uniformity.
FINDINGS:
A. 1. Most of the breaks (16) have occurred in the laterals and steps should be taken to significantly reduce these breaks.
2. The laterals, if needed to be replaced, would cost about $750,000.
3. The mains had one break in the one year of reporting time (9/25/07 to 9/04/08). This is considered normal.
4. Ten (10) breaks in the laterals occurred where the pressure in the mains is over 100 psi and (6) breaks occurred where the pressure was less then 100 psi.
5. The Ridge Golf Course in Auburn uses slow turn-on/off heads and they have had no pipe breaks in the past 10 years. Their piping is operated at approximately the same pressure as the LWW course.
6. The Benbow Engineering Report, dated 8/01/97, noted "Rainbird 700/750 series rotors tend to have a rapid-closing cycle; when multiple rotors are grouped, or blocked, on the same station, water hammer may become more pronounced".
B. 1. A catch-can test was done collecting water with the present Rainbird sprinklers, Model #700, and the distribution uniformity is good at 88% using the industry-accepted formula.
2. Per Rainbird specification, 82 psi is needed at the base of the head in order to get 70 psi leaving the nozzle. Each head has a pressure-relief valve so that any pressure in excess of 82 psi is not used.
C. The pressure relief valves PRV 1 & 2 may be regulating at less than the 85 psi as planned. These valves set the pressure for the front 9.
D. 1. Some air is entering the underground piping when the turbine pumps start up. The present Pump Station does have an air-separation chamber and air-release valve that is supposed to vent this air before it enters the underground piping. This apparently is not working as intended.
E. Much of the soil on the course appears to be hydrophobic (not capable of uniting with and absorbing water).
1. This adversely affects playability of the course because some of the areas are hard and some are soft. For example, the players tee off and all balls that had similar carry in the air end up in considerably different locations because some hit a hard spot and get a lot of bounce and/or roll and others that hit a soft spot get little or no roll.
2. This hydrophobic condition exists over most of our golf course fairways.
a. In the summer, where the grass looks stressed (yellowish),a screwdriver can only be pushed into the soil less than 2" ; where the grass is lush (dark green) it goes in 8" or more.
(1) The catch-can test of water distribution uniformity showed good uniformity (see Page 8 of 8) and there was some agreement of slightly less water being collected in the area of stressed grass.
b. Go to Google Earth, find Lake Wildwood, and then find the golf course. Look at each fairway on Maximum Detail and one can see light green and dark green patterns repeated on most fairways.
RECOMMENDATIONS:
A. Reduce the pressure of the Pump Station from 125 psi to 115 psi, nominal. (When operating at 125 psi setpoint, the pressure varies from 115 psi to about 135 psi.)
B. Replace the present sprinkler heads with slow turn-on/off. (At this time, Hunter and Toro heads are slow turn-on/off.)
1. Do a catch-can test of the Toro and possibly Hunter sprinklers.
2. Heads with the lowest operating pressure are preferred (the heads we have received from Toro are set to 60 psi at the nozzle and 68 psi at the base). These can be operated with 14 psi less line pressure than our present Rainbird heads.
3. Install new heads in the Back 9 first, because this is where we are having most of our breaks.
C. Evaluate the Replacement Reserves to determine if we can fund the replacement of all sprinklers in the 2009/10 and 2010/11 timeframe. This is currently estimated at $183,000 in total.
D. When repairing leaks in the pvc laterals, use schedule 80 fittings.
E. The PRV 1 & 2 should be serviced and reset to 85 psi. Mark Hadkin of Auburn Pump, who last serviced these valves at about 1998, has notes that recommend that the rubber diaphragm in one of the valves be replaced.
F. 1. When watering the greens in mid-afternoon in the summer, the pump control system is apparently ramping up too fast and it does not give the air-venting system time to work.
a. The watering time should be extended so that all the watering can be done using the 30 hp pump only (less than 300 gpm of water flow). This will take a few minutes longer to complete the irrigation cycle; however, the pump station should work better under this method, and it should have no adverse effect on the golfers. Start watering the greens, highest number first, so that a group of players is only affected one time per watering cycle.
G. Expand the tasking assignment of this sub-committee, or create another committee to include:
1. Analyze the soil chemistry.
a. Have soil samples tested by an agronomy testing lab to determine the actual nutrient content of our soil versus the desired nutrient content and if our soil is hydrophobic.
2. Review past usage, and cost, of fertilizer, insecticides, wetting agents, and soil amendments to reduce hydrophobic soil and to provide the nutrients needed.
3. Study cost-effective ways to apply the above-listed items.
a. Fertigation (fertilizer applied through the irrigation system). This was recommended in the 1997 Benbow report.
b. Cost of liquid fertilizer, insecticides, wetting agents versus the present method.
(1) Supposedly, fertilizer is significantly less costly when purchased in the liquid form.
4. Eliminate, or greatly reduce, hydrophobic soil.
5. Members of this committee should be free to contact vendors and suppliers for informational purposes only, but could not make any financial commitments for Lake Wildwood.
Attachments:
2. Issues
2. Pressure & Elevation, Front 9
3. Pressure & Elevation, Back 9
4. Chart of water distribution uniformity - presently used Rainbird heads