was constructed on Swanbourne Street, fed from the prison by a triple-expansion steam-driven pump that could take more than per day from the prison tunnels. Prisoners, relieved of manual pumping, were employed to supply wood and stoke boilers. The tunnels were closed in 1910, though the groundwater continued to be used for the prison's gardens. In 1989, diesel leaking from nearby tanks was found to have contaminated the water; however, the pollution was largely cleared by 1996 through bioremediation. The tunnels were opened to tourists in mid-2005. History 19th century While the Swan River Colony was established as a "free settlement" (unlike the penal colonies on the east coast), by the 1840s demand for cheap labour overcame an early reluctance, and the colony agreed to accept some convicts from Britain. The arrival of the first convict ship Scindian on 2 June 1850 was unexpected, as a sailing ship that had been sent ahead had been blown off-course. The colony's Round House jail was full, so the 75 convicts had to be left on the ship until a temporary prison was built. Comptroller General of Convicts Edward Henderson looked for a place to build a permanent convict establishment, and ultimately settled on the current site, on a hill overlooking Fremantle. The design for Fremantle Prison was based on the Pentonville Prison in Britain, but with diagonal cell blocks replaced with a four-storey linear structure, which would be the longest, tallest prison cell block in the southern hemisphere. Construction began in 1851, and work rapidly progressed following the arrival of the Royal Engineers later that year. They trained convicts to work with limestone, which was quarried on-site. The first priority was the construction of accommodation for Henderson and the prison warders, to relieve the expense of paying for private lodging. The prison walls were constructed between 1853 and 1855, while the gatehouse and associated entry complex was built in 1854 and 1855. Construction of the southern half of the Main Cell Block began in 1853 and was finished in 1855, with prisoners transferred from the temporary prison on 1 June 1855. Construction of the northern wing followed. The Crimean War saw the Royal Engineers recalled, leaving only one of their number, Henry Wray, to oversee the building's construction, which was completed by the end of 1859. During Western Australia's convict era, the prison was known as the Convict Establishment, and was used