POLE 1 DECONSTRUCTIONBENMORE SUBSTATION

Presented by:

Matthew Walker, Transpower

Terre Maize, 4Sight Consulting

Asbestos in floor tiles

and mastic

Potential areas of elevated

residual mercury, eg MAV pits

4

Primary Challenges

Project Objectives

• Employee health and safety protected during cleaning and deconstruction.

• Environmental protection during cleaning, deconstruction.

• Environmental protection in longer term by cleaning to allow draining of the backfilled basement.

• Minimise off-site disposal.

How to Clean up? - Pilot Test

Containment set-up over MAV

pits for mercury removal pilotContainment over tile/mastic

removal pilot area

Pilot Test

Foamshield tested, suppresses

asbestos fibre release to air

Sulphur and sulphur

based solutions trialled

Regulatory Challenges

• NES Soil does not apply

• No clean-up standard for elemental mercury in concrete

• Needed a pass/fail value for field instruments

• Asbestos containment and mercury presence adds to complexity of project

Clean Up Evaluation

• Initially considered soil standard; however, cleanfill landfill is more accurate

• Use SPLP to evaluate concrete for leachability to groundwater using the Class B (TCLP) Landfill criteria

• Correlate SPLP to XRF and MVI results to establish field pass/fail criteria

• Utilise product to allow asbestos removal without containment or release of fibres

Monitoring

• Wells within basement

– infiltrated water

compared with Class B

Landfill TCLP guideline

for mercury

• Tail race compared with ANZECC 2000

Implementation Management

11

Implementation Mercury

• XRF and MVI survey before and after

• Elemental sulphur for visual evaluation

• Mercury vacuum

• Concrete cleaning

• Concrete sampling, SPLP test

Implementation Asbestos

13

• Removal of tiles with no built containment

• Removal of mastic

What Worked Well

• Recordkeeping

during project

• Reliability of field

criteria

• Good working

relationship with

Ecan

• Site induction and

visits

Improvements

• Site visits – quick uptake of improvement observations, such as:

– Reinforce avoidance of cross-contamination

– Decontamination area upgraded with signage

– Task specific training

• Mercury cleaning method selected during pilot test created problems at full-scale

End Result• Over

2000m3 of concrete and basement concrete retained on site

• Reusable site

THANK YOU!