Valve Covers & Access Hatches
Water and Sewerage
The Melbourne Metropolitan Board of Works (MMBW) was the statutory authority reponsible for Melbourne’s water supply and sewerage system from the 19th century until its dissolution in 1994. MMBW valve covers are among the most common sidewalk features in Melbourne’s CBD, enabling localised shutoff to sections of water main in case of maintenance or emergency. The complexity of supplying and disposing of water throughout Melbourne necessitated some of Melbourne’s earliest networks of under-footpath services - to enable planning and maintenance of this system, the MMBW produced 1 inch:40 feet (1:480) scale plans of the innner city from the 1890s onward. These plans, today held by the State Library of Victoria, are among the best available resources for urban and architectural research on early 20th century Melbourne. Other water-related street services include MMBW water electrolysis hatches and the last remaining traces of the defunct Hydraulic Power Company high-pressure pipe network system.
MMBW Valve Cover
MMBW valve covers took on a wide variety of designs throughout 100-plus-year life of the organisation. Made from either cast or ductile iron, the typical example is square or rectangular and between 50mm and 200mm wide. Raised lugs for grip are often square or diamond-shaped, in varying patterns. The hatches are typically either hinged or designed to be lifted off with a pry tool inserted in a central hole. MMBW valve covers are sometimes painted for ease of identification, and frequently clustered alongside electrical, gas or other service covers.
Water Electrolysis Access Hatch
Melbourne’s electric tram network poses a distinct risk to the city’s water mains. A process known as electrolysis can cause rapid corrosion of metal pipework buried close to the electric current of a tram line. In the 1920s the MMBW began a program to protect its metal pipework from damage caused by this stray current, installing sacrificial zinc rods in sidewalk pits like the one shown here.
Melbourne Hydraulic Power Co. Access Hatch
Established in 1887, the Hydraulic Service Power Company developed a network of high-pressure water pipelines under the streets of central Melbourne to power industrial machinery and early passenger lifts. Responsibility for the hydraulic network later passed to the City of Melbourne, which maintained and used the system until 1967.