Project Case Study:
Substation No. 15 – Johnston Street, Annandale
HERITRAGE BACKGROUND Substation number 15 is the second oldest distribution substation in Ausgrid’s electricity network and was built in 1910, becoming the first substation to be built in Annandale. The Federation design of the substation was common during this period of expansion but now the substation is the last of its type still working for Ausgrid. SCOPE OF WORK The project scope of works was devised to meet Ausgrid’s obligations under the Heritage Act 1977. Works include replacing damaged roof timbers and the original slate roof, repair of loose stonework and cracked brickwork, replacing downpipes and hoppers, graffiti removal and repainting. The scope of works be summarised below:
- Mobilising site
- Scaffolding and protection work
- Re-roofing entire slate roof
- Replacing timbers, wall plates to masonry wall level
- Brick strengthening work: brick stitching, re-fixing of capping
- Installation of new roof trusses and framing timbers
- Removal and disposal of asbestos containing roof vent sheets
- Supporting structure for gutters and overflows
HERITAGE WORKS The vintage materials of the substation meant that specialist skilled tradesmen had to be used to carry out the restoration works. The roof was completely re-slated using authentic slate quarried in Wales and exported around the world to Australia to retain the character of the previous original slates. This work was performed by Murphy’s own in-house specialist slaters, who also replaced roof timbers with hard wood timber to retain the heritage fabric of the structure. The roofers also refurbished the original cast-iron downpipes and rainwater heads so the same pattern and specification of the original items could be conserved. All painting works performed on site were specified by the heritage architect and matched the existing original colour scheme. The whole project works were carried out in accordance with the designs of the specifications of the project heritage architect who inspected and approved the finished works. WORKING IN A RISKY ENVIRONMENT The project involved a variety of risks:
- Risk to the heritage appearance and fabric of the building
- Working at heights
- Working in an electrical substation with live transformers and switchgear
- Removing asbestos containing materials
- Possible exposure of electrical equipment to rainwater
- Vehicle and pedestrian traffic movement across the front of the site
- Crane lifting of materials
- Located between occupied residential properties.
Given the high risk nature of the site and the heritage significance, Murphy’s allocated a team with plenty of previous experience in live substations and heritage remedial work. The project team key members included Project Manager, Site Manager, Safety Coordinator and specialist tradesmen. All project personnel were trained in substation entry, electrical safety rules, environmental awareness, low voltage release, CPR and first aid awareness. An engineered hoarding and scaffold was erected at the front of the substation to provide protection to pedestrian traffic on the pavement as well as access to the work at heights for Murphy’s. Murphy’s were able to locate the site amenities including site office and toilet on the scaffold to save space. A small amount of asbestos cement sheeting was removed from the roof vent. This was undertaken by Murphy’s in-house under our own asbestos removal licence. An Asbestos Removal Control Plan and SWMS was developed, notification was given to Workcover, in accordance with the Code of Practice and WHS Regulations. All asbestos removers were trained and wore protective PPE during the removal process including P2 disposable masks, type 5 disposable coveralls and disposable gloves. An occupational hygienist attended site to monitor the works and issue a clearance certificate after inspection of the site for safe removal and decontamination asbestos. Murphy’s experienced scaffolders erected a catch scaffold platform across the entire roof at ceiling level to protect the live substation and switch gear. Exposed Live substation equipment was protected by screening and the construction of plywood boxes around equipment.
Scaffolding of entire substation ceiling.
The substation before commencing work.
The substation on completion of work.
Project Delivery and Quality Management. Materials were ordered to the specifications of the client’s heritage architect in order for all work to remain in keeping with the building original features. Inspection and Test Plans were used on the work to verify the process of ordering, receiving, installing and finishing project works. At the completion of the project a handover manual containing material specifications, asbestos air monitoring reports, clearance certificates, asbestos disposal receipts and materials warranties was issued to the client. Benefits offered to Client during Project Works;
- Improvement of building fabric and conservation of existing heritage aspects of the structure
- Project delivered by specialist tradesmen achieving high quality workmanship for all aspects including heritage work
- Substation functioned uninterrupted throughout the project works.
- No impeding of Ausgrid electrical maintenance activities
- Safety and environmental controls implemented during the project with no incidents.