Basement excavation work

Description

The contract comprises establishment of an excavation pit for sykehusbygenes [the hospital buildings] basement level including casting of the work deck. Helse Sør-Øst RHF shall establish a new hospital in Drammen. It has been decided that the new hospital will be located on the Brakerøya industrial area. The contract comprises establishment of an excavation pit for sykehusbygenes [the hospital buildings] basement level including casting of the work deck. The excavation pit must be dry and excavated in a water-tight sheet piling structure as most, or all places must also function as shoring of the uncompacted matter. The load on the sheet piling from soil and water pressure indicates that a bracing level must be established before excavation to the deepest depth can be carried out. Removal of bracing in other places will be included in a later contract and not to be included in this contract. Piling works, casting of basement and back-filling is not included in this contract. The works consists of the following main elements: — rigging for the contract, — pre-excavation and removal of old piling in the sheet piling line, — ramming of sheet piling, — excavating in the sheet pile pit including removal of old foundations and piles as well as removal of piles that are in the way of new piles, — shoring of piles (internal or external), — winter insulation of the sheet pile construction, — establishment of work deck, — measures in connection with treatment of polluted matter, — pumping out of water from the construction pit including purification of bilge water, — any necessary local lowering of the groundwater if there are leaks in the sheet piling, by means of pumping wells, — any necessary excavation outside of the basement construction pit to remove polluted matter, — filling works outside of the construction pit (option). The following main quantities are currently estimated: Sheet piling for waterproofing/shoring of the construction pit: 950 consecutive metres or 14 500 m2. Area in the sheet piling pit: 12 000 m2. Total volume of excavation in the sheet piling pit: 65 000 m3. Prior to the start of contract, the current building must be demolished to terrain in the area where contract 2102 has its target point. The area has currently 2 access roads. The access from the south-west has a limited height under the railway and can only be used for passenger cars and possibly small goods vans. The access from the north east must be used as the access for all construction traffic. The prior contract 2101, the Demolition and environmental restoring, is the responsible main contractor when Contract 2102 is initiated, up until 1.1.2020. After that the responsibility will be transferred to the Contracting Authority. The hospital and neighbouring access roads shall be filled with masses to achieve a flood secure level. Major masses are therefore required in order to fill up the area. The Contracting Authority wants this to be executed in an early stage where this is possible, due to future settling and are also included as an option to the contract.