Almost 90 culverts across Birkirkara’s main roads will eventually be connected to a massive tunnel below Valley Road as part of the EU-funded flood relief project.
The €56 million scheme will ease the pressure of rain water in areas prone to flooding. The works forced several roads in Birkirkara, Balzan, Qormi and Attard to be closed over the past weeks, including most of Valley Road, which should be re-opened next week.
Project leader Carm Mifsud Borg told Times of Malta that everything was moving smoothly and was within the set time frames and budget.
The project is designed to ease flooding in 12 localities: Balzan, Lija, Attard, Iklin, Birkirkara, Gżira, Msida, Żebbuġ, Qormi, Marsa, Żabbar and Marsascala.
Mr Mifsud Borg said the project was expected to be completed by September next year.
Excavation work on the five-metre high, 5.5-metre wide tunnel, which starts from Wied Inċita in Attard, is well under way. The tunnel will handle rainwater channelled from Attard, Balzan, Lija, Birkirkara, San Ġwann and Gżira and the surrounding areas. Some of the water will be directed towards reservoirs and the rest dumped into the sea at Ta’ Xbiex.
In all, about 11 kilometres of tunnels will be dug and then covered in two layers of specialised concrete to prevent damage by the gushing runoff water. A soak-away reservoir with a capacity to hold about 10,000 cubic metres of water has been built in Gżira and an application is still pending to turn its surface area into a car park. The reservoirs are designed to allow water to percolate into aquifers, providing them with much-needed replenishment.
These gratings are strong enough to withstand the weight of an aeroplane
During an on-site visit at Valley Road, Mr Mifsud Borg explained there would be an oil and grit separator across the road from the VAT Department to filter the first five minutes of rainfall before shutting off automatically. This filter will process an estimated 250 litres of rain per second, catching debris and stopping it from being carried along the roads.
There will be 82 culverts running through the main streets in Birkirkara, channelling water into the tunnel below.
Mr Mifsud Borg said the Birkirkara part of the project was expected to cost about €23 million. An estimated 67 cubic metres of water per second can pass through the tunnel underneath Valley Road, which usually turns into a fast-moving river whenever it rains heavily.