In 1908, Sydney’s rockchoppers won a spectacular victory against their employers and the New South Wales Government. The core of their grievances was the horrific danger of silicosis they faced in cutting sandstone for sewerage construction. In successive years, through their sectional union, they gained greater control of the labour market and used their power to reinforce unilateral regulation. Increasing costs, that flowed from labour shortages, work stoppages, and improvements these workers had made in their working hours and wages, created a crisis among public works contractors. The pro-contracting public sector authority responsible for sewerage construction – Sydney’s Water Board – developed a strategic response to the union which took advantage of the effects of the arbitration system on union representation among these workers. By shifting work away from contractors and the rockchoppers’ union and mechanising the most skilled work, the Board precipitated the demise of a militant union and its replacement by more tractable bodies.