The existing Bulwer Island Refinery recently shut down and was transitioned to a Jet Fuel Import Terminal. The Refinery infrastructure went through a systematic process of de-energising, de-inventory, and isolation, and once safely shut down and decommissioned the area was finally fenced off removing it from the extents of the live Jet Fuel Import Terminal.
The whole area on which the refinery stands was originally a tidal mangrove swamp that was reclaimed using sand dredged from adjacent areas in Boggy Creek and the Brisbane River. Piled concrete foundations support the weight of the process plant and storage tanks.
Liberty Industrial has been engaged by BP to demolish several decommissioned units within the old BP refinery site. The infrastructure to be demolished comprised of five Bitumen Blowing Units, Alkylation Unit, Alkylation Acid Risk Reduction Project Unit Modules, East Flare, and Fire Water Tank & Pumping Equipment.
The scope of works encompassed the demolition of all above-ground infrastructure within the site boundaries, the demolition of all footings, slabs, piles, and pavements to 1m below grade, the demolition of all pipe and electrical ground penetrations to 500mm below grade, the removal of asbestos and the disposal of residual bitumen within the bitumen tanks and pipes.
A key challenge was the disposal of residual bitumen. The demolition of the five Bitumen Blow Units (BBU) had approximately 575m³ of total bitumen waste. This includes an estimated 550m³ of bitumen sitting in the bottom of the tanks and 25m³ of bitumen-contaminated piping. It was unknown whether the bituminous material would be vicious or brittle until the tanks were opened. Fortunately enough, the majority of the residual product was brittle and the bitumen was loaded into plastic-lined trucks and disposed of off-site to an approved landfill.
Another significant challenge was the demolition of the 86.6m East Flare triangular structure. The structure was strategically demolished in three stages. The first stage involved the use of slings and lugs to support the flare pipes and secure them to the main structure prior to pre-weakening, welding angle irons to strengthen two braces, and the main column that was going to be significantly pre-weakened and removed at the final stage, oxy cutting and fully shimming several members of the structure.
The second staged involved pre-weakening the structure significantly further and removing a number of structural members. It was crucial that the second stage had to be done the day before drop day. This was to prevent any major structural loading on the pre-weakened members during unsuitable weather conditions.
The third and final stage was done on drop day. It involved doing final cuts and inducing the collapse of the structure using the 120t excavator. A 170m radius exclusion zone was implemented during drop day. Sentry points were set up at different locations and a number of lead-in roads were closed for a blanket of time.
Mechanical demolition of other refinery infrastructure was carried out using a 120t Hitachi excavator with 20m long reach arm, two 38t Volvo excavators, two brand new 25t Volvo excavators, a number of attachments including the Fortress 95-R shear, OSA RS 6000 Concrete cracker, two Genisis GPX 660 shears, grabs, buckets, and a magnet.