Carmel Krogh

Director

Shoalhaven Water

PORTERS CREEK DAM – MY “GOLDILOCKS PROJECT”

PORTERS CREEK DAM

DAM HISTORY

Porters Creek Dam was constructed in 1968 and consisted of a 17 metre high by 13 metre long

post-tensioned concrete gravity section with an

overflow spillway integral with the crest

DAM STABILITY ISSUES

• Dam incorporated 81 post-tensioned cables embedded 8 metres into the foundation and tensioned against headblocks at the crest of the dam

• 3 relaxation monitoring cables also installed during construction

• When tested in 1991, 2 of these monitoring cables failed

• A dam stability analysis undertaken in 2000 by the Department of Public Works concluded that upgrade work was required

THE PROJECT • Open Tender Process

• Leed Engineering

• $8.5M

• Limited window of opportunity for construction (prior to peak summer)

• Contract signed 11/11/15

After consideration of a number of options Council

resolved to construct a mass concrete gravity wall

downstream of the dam (effectively converting the existing dam to a gravity

structure and removing the dependence on anchorage

for stability).

CONSTRUCTION • Construction commenced

on-site in March 2016

• Lots of Challenges ! • Highway Intersection

• Access Rd

• Crane and Flight Path (Naval Base)

• National Park

MORE CHALLENGES

• East Coast Low Event 4-6 June 2016

GRAND OPENING !

BEFORE AFTER

First Spill – Saturday 18th March 2017

THANK YOU