Today’s question is
I would like to know if there is a requirement for a medic / ESO to worker ratio for the resources sector in Western Australia. Is there a point (Number or workers) where a second medic ESO is required? Also, if a Medic / ESO is required to be on Call 24/7 Should they be paid for being on Call.
The question of pay is an industrial law issue and not one I’m competent to answer. That question should be directed to the Fair Work Commission or a relevant trade union.
As for the ‘medic / ESO to worker ratio’ my answer is that I am not aware of any ‘requirement for a medic / ESO to worker ratio’. Modern work health and safety legislation is premised on the idea that the person conducting the business or undertaking will ensure that there are first aid and emergency procedures in place to reflect the risk. That approach is reflected in the Mines Safety and Inspection Act 1994 (WA) and the Mines Safety and Inspection Regulations 1995 (WA).
The regulations say that there must be an emergency plan (r 4.30) and there must be first aid personnel and equipment (rr 4.24 to 4.29) but there is no mandated ratio of personnel to first aid officers. In fact r 4.26 only requires that ‘a [singular] person qualified in first aid is available at the mine at all times when persons are working at the mine’ and that ‘a’ (again singular) person qualified in advanced first aid is available at all times.
It follows that at least the Mines Safety and Inspection Act and its Regulations do not establish ‘a medic / ESO to worker ratio’. Whether any industry standards do is another matter and not something I can comment on.
Australian Emergency Law 
The bigger question here is that mines in WA are using lower qualified people (Cert IV In Health Care). This qualification is for basic life support only and at times these ‘Medics” are many hours away from assistance and help. There are many places where Cert Iv is appropriate (such as close to towns with a paramedic service, or only a short run to a regional hospital), but the sad case in many cases the risk does not match the resource.