New Gasco Plant to throw away 140,000 tonnes of water
James Debono An annual 140,000 cubic metres of rainwater – the equivalent of 70 million bottles of table water – will be discharged into the sea from the new depot for Liquefied Petroleum Gas, sited in a disused quarry in ix-Xoqqiet, Birzebbuga.
The depot will be relocated from its present site in il-Qajjenza, just next to a residential area, to a safer site located on Malta’s most southern tip.
The Environment Impact Studies presented to the Malta Environment and Planning Authority show that an estimated 140 000m3 of rainwater presently enters the site, and drains into the ground. But when the new plant will be constructed, this drainage regime will change, as the quarry bottom will be covered with impervious material.
The Malta Environment and Planning Authority had asked the authors of the study to consider the storage of this vast quantity of storm water.
But the study excludes the construction of an on-site reservoir to collect the storm-water, as this would have to be located in the lower part of the existing quarry resulting in excavation works in the coralline limestone.
The construction of the reservoir is also excluded for safety reasons as it when it is not full to the brim it would also capture any gases leaking during operations.
“The smaller the volume of water in the reservoir, the larger the volume of heavier-than-air potentially explosive gases and the greater the safety risk,” the EIA points out.
The construction of a storm-water tunnel will also help keep the plant naturally ventilated and thus preclude the accumulation of potentially explosive gases in this zone.
The rainwater runoff from the site will be largely of good quality, but small-scale contamination could result because of contact with chemicals, and oils used at the establishment.
For this reason the storm water will be treated before being discharged into the sea. Water treatment shall involve the interception of any silts and oils before the water is discharged through a tunnel in to the sea.
The storm water will be channeled through a tunnel passing along the road network leading from the quarry to the cliffs overlooking the sea.
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