Bolivar digestor reunited with lifelong partner

A crane lifts the digestor steel cover back in place (Bolivar)
A crane lifts the digestor steel cover back in place

After spending months apart, one of the Bolivar Wastewater Treatment Plant’s anaerobic digesters has been reunited with its 118-tonne steel cover in a major milestone for SA Water’s $4.7 million upgrade of the structure. 

Initially lifted off in December last year, the 30m-diameter cover’s rehabilitation work included reinforcing and re-coating the roof’s structure, and installing a new insulation system to enhance biogas production. 

Related article: Bolivar’s biogas breaks renewables record

The same 350-tonne crawler crane sprung back into action to replicate its earlier feat—one of SA Water’s largest crane lifts—to expertly guide the cover back atop the digester earlier this month. 

SA Water senior manager of capital delivery Peter Seltsikas said the upgrade ensures the digester can continue playing it’s important role in sewage treatment for the next 20 years. 

“Our digesters enable a sustainable solution to treating South Australia’s number ones and twos by converting them into a source of renewable energy, while providing biosolids for use by local farmers,” Seltsikas said. 

“After the cover was first craned off, it was carefully placed on 32 temporary concrete blocks surrounded with scaffolding to provide safe access for our teams to get to work rehabilitating the structure. 

“The existing paint coating on the cover was initially removed by high-pressure water blasting to allow for an extensive condition assessment, which identified around 120 square metres of steel needed replacing. 

“Once the new steel plates were welded into place, we restored the cover’s internal insulation by injecting expanding insulating foam into small holes in the steel plates to help enhance optimal heat retention. 

“To further augment the cover’s structural integrity, we stripped any remaining surface corrosion on the cover before applying two layers of epoxy coating to protect the steel from future corrosion. 

“Taking the cover off provided an opportunity to perform a thorough clean inside the digester to improve its holding capacity, along with inspections of the structure and interior pipework to inform our future planning. 

“Safely reuniting the digester with its cover was another incredible feat underpinned by the tight collaboration between our people, Fulton Hogan and MAX Cranes, with the team now focused on completing the external roof insulation and cladding system before it’s brought back online. 

Related article: SA Water Swan Reach pipeline powered by green energy

“This process will take around three months, as we’ll need to get our bug colonies functioning by introducing ‘seed’ sludge to establish a strong population of bacteria that eat away at the new sludge to produce biogas. 

“Despite taking the digester offline for our upgrade, our Bolivar plant has reached record levels of renewable energy generation in recent months through our other five digesters and we’re hoping to reach new heights once they’re firing on all cylinders.” 

Previous article“No excuse”: Ergon’s appeal to abusive customers
Next articleTiwi Islander’s victory: Santos to vacate Barossa gas