Three contractors eye 'mediocre' limestone

Three building contractors have placed tenders to buy limestone dug from the landfill site at Ghallis ta' Gewwa, even though geological studies say it is of "mediocre quality".

When Ghallis was first earmarked for the project in 2004, a controversy had erupted over the quality and financial value of the limestone there amid strong indications that it was "worth its weight in gold". However, a series of geological studies later found the rock was of no use except for rubble.

Still, Polidano Brothers, Blokrete Limited and Ballut Blocks Limited are each ready to buy half of the 1.2 million cubic metres of limestone which are to be dug to create the landfill, The Times can reveal.

Blokrete Limited are offering 28c5 per tonne, Ballut Blocks 39c per tonne while Polidano Brothers placed the highest offer of Lm1.53 per tonne to buy the limestone from WasteServ Malta Ltd. Polidano's offer includes the cost of "excavation of 2,333,000 tonnes", the notice board of Department of Contracts shows.

The remaining 600,000 cubic metres of excavated limestone will be used for "screening" on site, the environment impact statement (EIS) states.

According to a study conducted by architect Alex Torpiano in May 2004, referred to in the same EIS, mechanical and physical tests on core samples taken from boreholes at Ghallis showed that the average compression strength of limestone samples from the site was of 12.2N/mm2 (with a range of 4.7N/mm2-24N/mm2) - less than half the strength of good quality Lower Coralline Limestone which is in the order of 30 to 40N/mm2.

Speaking to The Times, Prof. Torpiano explained that limestone with a strength of 12.2N/mm2 was "nowhere near" the quality of material needed to make bricks or concrete slabs, adding that the Ghallis limestone was even weaker than globigerina limestone (tal-franka), the strength of which is normally around 20 N/mm2.

Asked what the limestone could be possibly used for, Prof. Torpiano said it could perhaps be crushed and used as a filler in the bottom layers of a road. "It cannot even be mixed for the upper tarmac layers. That limestone is usually in the range of 50N/mm2," he said.

Blokrete director Joseph Fenech said that though the Ghallis limestone may not be as strong as other kinds used to make very resistant concrete, it could still be used in leaner concrete mixtures and also as a filler.

When the Ghallis limestone was still thought to be valuable, the government had thought of quarrying all the stone before opening the landfill. Since quarrying would have taken up to three years, it decided to open temporary landfills inside two decommissioned quarries near Mnajdra and Hagar Qim temples until waste could start being taken to Ghallis.

The decision had raised public outrage and plans were scrapped when geological studies finally concluded that the rock at Ghallis was of a low quality. After all, it could not be used for concrete or road construction and extracting it was only justified to create a landfill void.

On Thursday, the Malta Hotels and Restaurants Association (MHRA) slammed the government for not having answered its question on what would be done with the limestone.

During a public consultation meeting on the Ghallis landfill last week, The Times asked what were the terms of the call for tenders and which companies had placed bids. WasteServ Malta chairman Nick de Giorgio said "the successful bidder will be made public".