Is the client the golf course operator? If so, I'd remind them of their duties. Golfers on a course accept the risk of being hit by a stray ball as part of their sport, doesn't mean you have to though. How long is the work likely to last? If it is a long project, they could do something with screening nets. These cost around £1 per sq. m for the net plus post and fixing costs. Height needed will depend on size of project. Short term small projects like minor drainage works - could you use vehicle/s or cargo containers as a screen. On a slightly cynical note, ask the person who is refusing to close the hole if he would be happy to let you use his car as a screen. You can bet the answer will be no. I suspect the thought of damage to the fairway or costs associated with netting may cause them to reconsider closing the hole.

The HSE have a publication on golf course maintenance and management which will answer all your questions - see link below. However, being an avid golfer with a passing interest in h&s I can confidently say that you can close a hole/green if work is taking place adjacent to it. A temporary green is often set up well short of the green where maintenance work is taking place. The safety of those working on the course takes precedent over any inconvenience to the golfers. http://www.hse.gov.uk/la...ws/aug08/newguidance.htm