These notes may be of interest to those who are curious as to how the golf course is affected by stormwater, and secondly, the sources of our irrigation water.
The stormwater catchment area which surrounds the course and feeds into the course is approximately three times the area of the course itself.
The largest portion of this catchment area is on the west and north-west sides of the course. It extends to the ridge on the west side of Pittwater Road and up Mona Vale Road for about 800 metres. Stormwater run-off from building roofs, roads and other pavements is funneled into the golf course via pits and pipelines which run in an easterly direction. The majority of it goes into
the two large pipelines which underlie the humps in the 5th,7th, 11t , 15th,and 18th fairways .
These pipelines discharge into the large dam if required for irrigation, or directly into the creek adjacent to the 16th green and the 17th tee. The creek flows into the pipeline which discharges into the ocean from the beach. Water from the catchment on the south side of the course including Mona Vale hospital and surrounding grounds feeds directly into the large dam via the pipes in front of the 18th tee.
The large dam is the final collector for the piped drainage systems and groundwater from seepage and possibly underground springs. In wet weather it does not have enough capacity to take all the incoming stormwater and the excess overflows into the main pipe system at the north end of the dam and flows under gravity to the ocean.
The stormwater is partly treated before entering the golf course area. Pittwater Council has installed five large gross pollutant traps and one smaller trap in the grounds beyond the western side of the course. MVGC has installed two smaller traps which are located on the south-west side of the course. These two traps are properly maintained by MVGC. The traps installed by the Council have to be maintained by the Council. If this is not done adequately the filters are bypassed during heavy rain and the rubbish goes onto the golf course. This sometimes happens. Stormwater from the southeast area including the hospital is not treated but this does not cause any significant problems.
Drainage is an on-going issue for the Club. However, considering the catchment area, the flat low-lying nature of the course, and the clay/rock sub-strata, the course recovers well after wet weather .This is largely due to the sub-soil drainage system and diligent maintenance.
All water for irrigating the course is pumped from the large dam. No Sydney Water mains supply is used.
In summer and other high water demand periods, all water flowing through the large stormwater pipes is directed to the dam. If further supply is needed to maintain the required dam level, bore water is pumped from the bore which is located near the greenkeeper's shed. There is sufficient capacity available to meet the irrigation demands. Mixing the bore water with the dam water provides suitable dilution of the higher salt content of the bore water.
In winter, the flow in the two large stormwater pipes goes directly into the ocean. This is done so that the dam level stays low enough to ensure that the Course stormwater drains can flow into the dam but remains high enough for irrigation requirements .
In conclusion, the Club has installed an irrigation system which effectively uses recycled stormwater and does not use the mains water supply.