1857: Work completed on first part of the Bennelong Sewer to discharge sewage as far out as possible into the harbour. This would service the more elevated areas, whereas the Tank Stream in Hunter St and King St as a bolted cast iron oviform aqueduct. This sewer (and possibly stormwater) network had the effect of draining the swamp area that had previously supplied some water to the Tank Stream, making the Tank stream more polluted by being less "cleansed". The section of the Tank Stream from the Sydney Cove to the Interception Chamber in Pitt St was completed, approx. 200m. The section at the mouth (approx. 5m has been strengthened with concrete in the two filleted corners. The next 10 m is sandstone arch. The next 15m section has the original stone floor overlaid with concrete, date unknown. The remaining section up to the Interception Champer (approx. 170m) is sandstone arch. 1858: Independent outfalls also completed at Woolloomooloo, Hay Street and Black Wattle Bay. Over the next 20 years, approx 10 other minor outlets were also opened. 1860: The sandstone arch between Bridge St and Hunter St was constructed. This was done to reduce odours from the previously open sewer/stormwater that up until that time had been more of a slops line. 1866: Section from south of Hunter St to Martin Place was formed as an open stone channel. In late 1870s was converted by roofing with an arch to oviform, whereas more southerly section was oviform invert with a flat roof, where it passes under Challis House... (Other parts were replaced in 2001 as part of the Angel Place project). Two sections were laid as oviform through the future GPO. To the south, two sections were laid as brick oviform and with some amendments in 1878. 1878: The brick oviform section from the Interception Chamber to Bridge St was constructed by contract for the City council. This was built to replace the open section that ran through private property. At the southern end there is a transition section (reducer), which leads to the sandstone arch, which is in Tank Stream Way (formerly Hamilton St.). 1879: The section from Bridge St to Hunter St, with its sandstone arch roof in place has its floor slabs lifted and re-instated with mortar foundations to water proof the floor for its use as a sewer. In addition a terra cotta "scouring channel" was