The NZ Transport Agency says contractors will use explosives to break up and clear massive boulders brought down onto the Milford Road by a major landslide on the weekend.
NZTA Southern Area Manager Peter Robinson says drilling rigs arrived at the slip site this morning, and had been working throughout the day to drill holes into the boulders. The next step would be to drop high-powered explosives into the drill-holes, in order to break the boulders down into pieces small enough to be removed from the site.
"We're dealing with solid granite boulders, some weighing around 200 tonnes, so we can't just load them onto a truck or a digger. The quickest way to do the job is blast these giants into smaller pieces, and that's what we're doing at the moment."
Mr Robinson said the work will be carried out as quickly as is safely possible, and the site will be closely monitored to ensure the safety of workers. He said at this stage the agency was still aiming to re-open the road to a single lane by this Wednesday.
Mr Robinson said the length of the closure and the timing for a full re-opening to two lanes would depend on how quickly contractors are able to break the large rocks apart and remove them.
"The weather is not going to be as settled as we had hoped, and we can only blast safely in daylight hours. This means getting rocks drilled and blasted as quickly as possible. Rain is expected late today and there is a possibility of snow on Wednesday. Blasting cannot be done in the rain, but the removal of material can. The safety of the people working underneath the slip is paramount and if the rain becomes too heavy operations will have to be pulled back. We're still hopeful for opening to a single lane by Wednesday, but Mother nature will have the final say.”
Mr Robinson thanked people for their patience, and said a further update would be provided on Wednesday morning.
For further information on weather conditions and other road closures in the area, updated every two minutes, visit www.highwayinfo.govt.nz(external link).