INTERNATIONAL SOCIETY FOR SOIL MECHANICS AND GEOTECHNICAL ENGINEERING This paper was downloaded from the Online Library of the International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE). The library is available here: https://www.issmge.org/publications/online-library This is an open-access database that archives thousands of papers published under the Auspices of the ISSMGE and maintained by the Innovation and Development Committee of ISSMGE. The paper was published in the proceedings of the 12th Australia New Zealand Conference on Geomechanics and was edited by Graham Ramsey. The conference was held in Wellington, New Zealand, 22-25 February 2015. Waterview Connection: Environmental impacts of a deep drained trench S.J. France1 and A.L Williams2 1Beca, Beca House, 21 Pitt Street, P.O. Box 6345, Wellesley Street, Auckland, 1141, New Zealand; PH (64) 9 300-9000; FAX (64) 9 300-9300; email:
[email protected] Beca, Beca House, 21 Pitt Street, P.O. Box 6345, Wellesley Street, Auckland, 1141, New Zealand; PH (64) 9 300-9172; FAX (64) 9 300-9300; email: ann.williams@beca./com ABSTRACT The NZ Transport Agency’s Waterview Connection project involves the construction of 4.8 km of motorway to complete Auckland’s Western Ring Route. Half of this new link will be tunnelled; the remaining half is surface highways and approach trenches. The Southern Approach Trench (SAT) is 400 m long with a temporary excavation up to 29 m deep, through basalt lava flows, Quaternary alluvium, residual soils and Tertiary age interbedded sandstones and siltstones. The concept design considered a drained base with a grout curtain through the basalt and cut-off walls through underlying units to control groundwater inflows and limit environmental impacts such as drawdown, stream depletion and consolidation settlement.