tunnelling-journal (1)
tunnelling-journal (1)
  • Home
  • Print
    • Subscribe
    • Tunnelling Journal
    • Breakthrough
    • ITA Activity Report
    • A&NZ Journal
    • WTC Preview
    • Media Kit
  • Digital
    • Newsletter
    • E-Shots
    • TJ Digital edition
    • Products Page
    • Media Kit
  • Conferences
    • BTS Conference and Exhibition
    • Cutting Edge 2022
  • Buyer’s Guide
  • Events Diary
  • Jobs
  • About Us
  • Contact Us
  • Podcast

Home > Realignment for Lake Mead Intake No 3

Realignment for Lake Mead Intake No 3

Amanda Foley

Written by Amanda Foley on 11/02/2011 in News

Tagged: underground

On February 10th, the cost and schedule impacts of a 20˚ to 25˚ re-alignment of the Lake Mead Intake No 3 starter tunnel and TBM assembly cavern, were outlined in a notice of agenda for the February 17th Board of Directors meeting of the Southern Nevada Water Authority (SNWA). The recommended negotiated change order being put before the Board is valued at $39.5 million and extends the contract completion date by 593 calendar days.

The change order comes following three major inundations of excavation works being undertaken by contractor Vegas Tunnel Constructors (VTC) – which comprises Italy’s Impregilo and its US subsidiary SA Healy – in the last seven months. In early 2010, while excavating the underground chamber and starter tunnel preparatory works for assembly and launch of the project’s 23.6ft (7.2m) diameter Herrenknecht Mixshield TBM, VTC encountered conditions that it claimed were more difficult than represented in the contract documents. Then, at the end of June last year – about 250ft (76m) into the 350ft (106m) long starter tunnel – VTC experienced a significant inflow of material and water over a period of several days, which flooded the 200ft (60m) long TBM launch chamber and rose about 150ft (46m) up the 600ft (182m) deep access shaft (see NATJ digital edition, Aug/Sept ‘10, p5).

After re-entering the underground works and while attempting to recover lost progress, two more inflows subsequently occurred – on October 27 and New Year’s Eve – convincing VTC that an adjustment of the alignment should be pursued to avoid the problem area.

VTC won the $447 million design-build contract to construct the Lake Mead No 3 Shafts and Tunnel in March 2008. Arup is the contractor’s designer and Brierley Associates is geotechnical engineer. The tunnel is part of a $700 million new deep water intake program by SNWA to secure supply of water from Lake Mead to Las Vegas and surrounding region.

More to follow soon…

Comments:

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Search

Digital Edition

More Like This

16/05/2022

Blue Mountains Tunnel Option confirmed

Blue Mountains Tunnel Option confirmed

The NSW Government has confirmed the 11km toll-free tunnel from Blackheath to Little Hartley as the preferred option following an…

19/04/2022

Ayesa wins Santiago Metro Line 7 contract

Ayesa wins Santiago Metro Line 7 contract

The Santiago Metro in Chile has awarded Ayesa, a global provider of technology and engineering services, an €11M, 66-month contract…

18/05/2022

Auckland Light Rail opens tender process

Auckland Light Rail opens tender process

The tender processes for the $14.6bn Auckland Light Rail and the Additional Waitematā Harbour Connections project have opened, marking an…

  • Contact Us
  • Media Kit
  • Magazine Archive

Newsletter

The latest from the Tunneling Journal direct to your inbox.

Social



Enquiries

TGS Media Ltd
The Old Library
Webster House
Dudley Road
Tunbridge Wells
TN1 1LE
United Kingdom

© Tunnelling Journal. All Rights Reserved. Privacy Policy / Terms & Conditions. Admin

We use cookies to ensure that we give you the best experience on our website. If you continue to use this site we will assume that you are happy with it.OkRead more