Sealing Deep Site Investigation Boreholes - Phase 5

Tender description

RWM's working model for the proposed procurement strategy is for a single contract award with a suitably qualified contractor to deliver Phase 5. This strategy may change based upon the outcome of this market engagement and further development of the procurement strategy. The contract will be for a period of 5 years with an option to extend this for a further 2 years. A DRAFT Contract Technical Specification and Questionnaire can be accessed by registering on the RWM procurement tendering system here: Sellafield Ltd (eu-supply.com) For background on the borehole sealing project, please see http://rwm.nda.gov.uk/publication/sealing-deep-site-investigation-boreholes-phase-1-report-rwmd03042/ (Phase 1 output) and http://rwm.nda.gov.uk/publication/sealing-deep-site-investigation-boreholes-phase-2-final-report/ (Phase 2 output). Activities to be included in Phase 5 will consider 'small-scale' laboratory work on materials such as bentonite, 'large-scale' laboratory work (e.g. using 20m mock-up boreholes), natural analogues (currently progressing via a series of international collaborative projects), a continuation of work on bridge plugs (a collaboration between RWM and two international waste management organisations), field demonstrations in pre-existing boreholes up to 2km deep and in underground research laboratories. No borehole drilling will be undertaken. However, preparing a borehole for sealing may require rehabilitation, removal of abandoned in-hole equipment, milling and under-reaming of a window in borehole casing, etc. - access to coiled tubing and drill string technology is anticipated. Bentonite has already been chosen as the seal material for use in boreholes in lower strength sedimentary rocks and higher strength rocks. Bentonite will be emplaced in boreholes in Phase 5 via use of the Downhole Placement System, a tool has been developed for this project. A different approach can be followed for a borehole penetrating an evaporite layer in Phase 5.