After Vignoles withdrew, the civil engineer Joseph Locke took over as a consultant and re-evaluated the project. The estimated costs were doubled from the £98,467 figure produced by Vignoles to around £200,000 and contractors were provided with new, highly detailed specifications. Locke supervised the construction and prepared contingencies. Soon after taking over, he reported that the amount of water being encountered required more powerful pumps. Although the number of people employed reached 1,500, generally there were around 400 in the tunnel because of limited space in which to work. It was estimated that around 157 tons of gunpowder were consumed during blasting, while over 8 million tons of water were pumped out during construction. The first tunnel was completed during 1845.