From todays press release from Colossus (CSI). Now, I'm not going to go back to grade 10 geometry here so I'll estimate that if this 'decline' was on a slope of approximately 28 degrees that the 3500 metres would take it about 1000m, which is what Tilsley has requested.

"Colossus would also like to announce that development of a 3,500 metre underground decline has officially commenced. The decline will provide access for underground exploration and definition drilling, allow extraction of a bulk sample to evaluate the geostatistics of the bonanza-grade zones to facilitate a better understanding of the potential resource, and provide access for eventual underground production. The cost of the decline is estimated to be CDN $15 million and is expected to take 12 to 18 months to complete. However, underground drilling will commence in early 2011, well ahead of the decline completion. Colossus has also started earthworks on other site infrastructure including a future plant site, camp site, maintenance facilities, offices, and the tailings impoundment and has already completed earthworks for the underground portal and upgrades to the road into Serra Pelada"