EXECUTIVE SUMMARY i
1.0 INTRODUCTION 1
1.1 A-Team Activities 1
1.1.1 Slurry Wall Panel Leaks 1
1.1.2 Roof/Wall Interface Leaks 2
1.2 The Waterproofing Task Team 2
1.3 The Leak Task Force 2
2.0 PROJECT BACKGROUND 3
2.1 General Tunnel Construction 3
2.2 Tunnel Waterproofing History 8
2.3 Waterproofing Performance Requirements 8
2.4 Waterproofing Specification Requirements 9
2.5 Waterproofing Details 9
2.6 Waterproofing Task Team 11
2.7 Quality Assurance/Quality Control (QA/QC) 12
3.0 SLURRY WALL PANEL LEAKS 13
3.1 The Problem 13
3.2 Leak Incident Details 13
3.3 Repair 15
3.4 Slurry Wall Construction Issues 16
3.4.1 Inadequate Cleaning of Slurry Trench 16
3.4.2 Improper Modification to the Reinforcing Cage 16
3.4.3 Improper Tremie Concreting Method 16
3.5 Inspection Plan for Other Walls 16
3.5.1 Initial Inspections 16
3.5.2 Expanded Investigation 17
4.0 ROOF/WALL INTERFACE LEAKS 18
5.0 LEAK REMEDIATION 18
5.1 Slurry Wall Panel Leaks 19
5.2 Roof/Wall Interface Chronic Low-Level Leaks 22
6.0 FINDINGS AND RECOMMENDATIONS 25
7.0 CLOSING REMARKS 26
8.0 ACKNOWLEDGEMENTS 26
APPENDIX