ASCO was selected by Halton Region to refurbish the existing digester gas sphere at Skyway WWTP. The digester gas sphere is designed to capture and utilize biogas produced during anaerobic digestion of sludge. The biogas can be used to generate electricity or heat the plant. The digester gas sphere contributes to pollution prevention and reduction of greenhouse gas emissions.

The project was centred around removing the sphere exterior coating, repairing areas of the sphere that had degraded, and recoating the sphere with a high-performance epoxy paint system. Before the digester gas sphere work could start, the residual sphere biogas needed to be purged with nitrogen. The entire exterior of the sphere was scaffolded, hoarded and heated to ensure environmental conditions remained consistent during the coating phase. 

ASCO was also required to replace the pressure relief valves (PRVs) and hatches, add a new exterior staircase to service the PRVs, and add new lightning protection.

Once the work was complete and the sphere was ready to be put back in service, ASCO and team were required to perform a pneumatic pressure test on the sphere. This involved strict adherence to TSSA fuel gas department regulations and procedures.