Tunnel water 'may contain drainage'

The person who oversaw digging works for the Sta Venera tunnels almost two decades ago is calling on the authorities to ensure the leaking water does not contain drainage.

Brian Blackburn is concerned that a sewage leakage that existed when the tunnels were constructed may have remained unsolved.

The increased water seepage led to the closure of the northbound tunnel last Saturday evening. The tunnel was reopened after the Malta Transport Authority (ADT) determined there was no immediate concern for public safety.

Mr Blackburn explained that he was the foreman in charge of the excavation works. Before the tunnels' digging started, several boreholes were dug in the rock to test its stability.

One of these boreholes passed through a cave where drainage had been collecting as there was a leakage in the area.

When the digging of the tunnel started, that borehole was hit and drainage gushed out of the cave and into the tunnel, Mr Blackburn said.

Questions sent to the Water Services Corporation remained unanswered. However, the corporation said it was carrying out surveys of the drainage and water mains located above the tunnel to identify the source of the leak, while the Network Infrastructure Directorate was inspecting rain water culverts.

The ADT said a structural engineer was surveying the reinforced concrete tunnel lining to determine whether any damage had been caused as a result of the water ingress and recommend any necessary repairs.

If the source of the leak was not identified by the end of October, authorities would consider attaching a water catchment system to divert the leak to drainage channels running along the tunnel's sides.