1 Dredging and Disposal Summary of Proposed Activities and - - PowerPoint PPT Presentation

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20 March 2020

Dredging and Disposal Summary of Proposed Activities and Discussion on Submissions and Impacts

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Our Presentation Today

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POAL’s Disposal Consent POAL’s Capital Dredging Consent Application Concerns Raised in Consent Submissions Some comments on Northport POAL’s 30 Year Plan

The Port may move…

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We figure this will be at least 30 years. This is the horizon used for our 30 Year Masterplan.

Port Future Study

“Short-term pathways need to be created to enable the Port to continue to operate efficiently prior to a planned new Port being established due to the substantial lead times involved. In this regard, the CWG identifies that additional berth length needs to be provided to fulfil the short and medium term capacity requirements of the Port in response to cruise and multi-cargo requirements.”

Infrastructure Update – Complete/Underway

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Fergusson Container Terminal

• 3rd berth FN completed
• 3 new cranes tested
• Road grids remodeled
• Hatch Lid Platforms on all 8

cranes

• Lash Platforms on all 8 cranes
• New layout, 10 hectares of

repaving

• Southern Reefer (900 plugs)

complete

• Reclamation ongoing

Automation

• All 27 A-Strads under LET
• Over 13,000 hours of testing
• approx. 500 hours per A-strad
• 30 odd Locata poles raised
• 22km of trenching for fibre optic

cabling

• Project on planned time line for

Phase 1 end March 2020

• Automation from truck grid to

Terminal stack – manual from terminal stack to/from crane

Multi-Cargo

• Building of 5 storey car handling

facility

• New tug berth completed

Infrastructure

• Demolishing of 3 cranes on

Bledisloe

• Consent obtained for disposal of

dredgings at sea

• Consenting for channel deepening
• Development of Freight Hub

infrastructure for Supply Chain strategy

Project Timeline

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The remaining Masterplan projects: 1. Demolish Shed 51 and part of Bledisloe B1 Wharf – 2021 2. Construct North Berth at Bledisloe – 2021/2023 3. Construct roof top park on car handling building – 2022 4. Relocate ships from Captain Cook to Bledisloe north – 2023 5. Replace wharf structure at south end of Bledisloe west – 2023/2024 6. Construct new sea wall south of Marsden Wharf – 2023/2024 7. Remove Marsden Wharf and deepen Captain Cook/Bledisloe basin – 2024/2025 8. Deepen channel – within 3 years 9. Engineering Workshop – design underway

• 10. Rail Grid Automation
• 11. Extend FN Wharf

Proposed Capital Dredging

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• 15 year consent sought for 2.5m m3

capital dredging

• Staged - dredging only when required
• Stage 1: for 6-7,000 TEU vessels

already calling in NZ – starting in 2021

• Stage 2: for new 13,000 TEU

Panamax class vessels – expected to start in 2025–2027

• Application includes maintenance

dredging within the channel

• All main Australia / NZ ports preparing

for Panamax class ships

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Current Capital Dredging Consent Application

Capital Dredging Consent – Regulatory Framework

Consenting framework in the Unitary Plan:

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Capital dredging is a restricted discretionary activity

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Restricted matters of discretion include:

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the effects of construction works methods, and the timing and hours of operation;

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the effects of the location, extent, design and materials;

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effects on coastal processes, ecological values, water quality including the release of any contaminated sediment, and natural character and landscape values;

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effects on public access, other users of the coastal marine area, harbour traffic, and navigation and safety;

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effects on existing uses and activities (including significant infrastructure);

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effects on Mana Whenua values;

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effects on historic heritage; and

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consent duration and monitoring.

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Maintenance dredging activities are a controlled activity

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Recap of Previous Dredging Activities in the Channel

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• Ports need to dredge to maintain

safe navigation

• Channel dredged number of times

since the 50’s

• Previous capital dredging

consented to 13.0m in 2001

• Only undertaken to 12.5m 2004-

2007

• Material used to reclaim

Fergusson Terminal

• Fergusson Terminal complete by

2021

Historic Channel Dredging

Stage 1: Dredging

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• Channel design maximises use of tidal

windows to minimise dredge volumes

• All dredging within existing precincts
• Depth of material to be removed varies

FN Berth and Approaches Location Stage 1 Stage 2 Dredged Volume (m3) Dredged Depth (CD) Dredged Depth (CD) Shipping lane – bends

• 13.5m
• 14.2m

1,105,100 Shipping lane – straights

• 13.5m
• 14m

1,149,300 Fergusson approaches

• 13m
• 13.5m

184,100 Fergusson North Berth

• 15.2m
• 15.2m

61,100 Total 2,409,600 Navigation Channel

How do we dredge?

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• We use a barge mounted excavator
• Bottom opening hopper barge

loaded directly by excavator

• Methodology used for many years

around Auckland

• Low impact - minimises sediment

release and disturbance to other users

• Duration of works:

― Stage 1 approximately 2 years ― Stage 2 approximately 3-4 years

Dredged Material Disposal

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Disposal Permit

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• POAL granted (by EPA) a 35 year

disposal consent at Cuvier Disposal Site (CDS) in June 2019

• One of five designated disposal sites in

NZ, in use since the end of WWII

• POAL (and others) have used site

previously

• POAL needs at least 1 disposal option

when Fergusson Terminal is completed next year

• Consent authorises disposal of capital

and maintenance dredged material

CDS Disposal Site Location

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Characteristics of Disposal Site

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Behaviour of dumped material Water currents

Application found disposal will not adversely affect local environment outside designated area (or Great Barrier)

• Disposal site – 700m deep on side of

continental shelf - currents low and dominated by north-south flow

• CDS is 4 nautical miles diameter –

disposal to occur within 250m of one location in CDS

• Over 90% reaches seabed directly as a

plume

Seabed characteristics

• 10% of fines stripped on way down

and deposited in CDS or close to CDS boundary

• Contamination and toxicity levels

assessed / approved before disposal

• Assessments involves
• contaminant levels
• bioavailability (elutriate testing)
• species toxicity
• Assessment compared against

published ANZEEC guideline values

• Sediments concentrations that do not

pass assessment(s) not permitted to be disposed off at site

Characteristics of Disposal Site

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Far field modelling output Near Field Modelling - Depth of deposition (microns) Note that the colour bar scale is a logarithm scale −1 and −2 equate to thicknesses of 0.1 and 0.01 mm, respectively.

Capital Dredging Summary of Submissions

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Main Points Raised in Submissions

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• Lack of Consultation
• Impacts on the Environment
• Impacts on our Food Basket (from disposal)
• Duration of Consent
• Alternatives to Disposal / Beneficial Reuse
• Transit of material through Hauraki Gulf / Emergencies

Consultation

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• POAL has engaged with wide cross

section of mana whenua and stakeholders to date

• POAL requested notification of

dredging consent

• POAL is keen to listen to

stakeholders and address concerns where we can

Unitary Plan Port and Navigation Precincts

Environmental Concerns

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Key topics raised:

• Nature of material and levels of contamination
• Increased sedimentation and effects on marine environment
• Effects of sediment on water clarity and on marine life (e.g. on snapper)
• Effects on coastal birds
• Effects on marine mammals
• Biosecurity

Capital Dredged Material Characteristics

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• Material is sediment that filled the historic river

valley when sea level rose after the last ice age. All but surface sediments pre-human.

• Surface material ranges from very shelly to muddy

sand and sandy mud

• Below surface - material consolidated less water

content

• Some subsurface siltstone and Parnell grit at south

bend of channel

RC-E-236B RC-B-108B Subsurface sediments in the Rangitoto Channel

Sediment Contamination

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• POAL has examined sediment quality in

channel in 2001 and 2019.

• Channel remote from any direct sources of

contamination.

• Most of the sediment is subsurface and

expected to be uncontaminated.

• Some common urban contaminants can be

identified (lead, PAHs etc.) in the surface sediment.

• Concentrations are all lower than ANZECC

(2018) guidance values with exception two subsamples in FN berth approaches that contained TBT.

• Consistent levels of contamination over

time - Lead levels decreasing.

Sediment Contamination

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• No waterborne toxicity expected based on 2019 tests and previous waterfront elutriate

testing

• EPA still requires further testing for any disposal at CDS and must approve sampling plan

before sampling and testing

• Additional sampling for EPA will involve:

― Coring / samples collected randomly across full depth of dredging ― More analysis for trace elements ― Analysis for persistent organics ― Analysis for TBT particularly focused at FN berth due to results to-date ― Additional elutriate testing if required ― Toxicity testing if required

• Results reviewed by EPA prior to approving material suitable for disposal at sea

Impacts on Marine Life (sedimentation)

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• During dredging sedimentation of coarse material
• ccurs adjacent to dredge and silt and clays settle in

the far-field.

• Much of the “adjacent” sedimentation in channel will

be dredged or will have just been dredged.

• Sedimentation plates put in for 2004-2007 dredging,

no sediment build up detected.

3 4 5 6 8 Transport path

• f fines on flood

& ebb tide Depositional zones

Inferred transport pathways and depositional zones

• f fine material (< 0.062mm)

Dredging at FNB – 1 year sedimentation Dredging at north end channel – 1 year sedimentation

Water Clarity)

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• Water clarity in Hauraki Gulf improves with

distance from land

• Total Suspended Solids (TSS) is a good

proxy

• In lower Harbour TSS 9 mg/L. In the

Rangitoto Channel TSS median 10.6 to 11.6 mg/L at three sites (similar to average of 7.2 mg/L measured in 2003-2008)

• TSS in the channel also varies with the tide

state (velocity) with + 10 mg/L change during the spring tide

Water Clarity)

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• Dredging releases some sediment
• Modelling of sediment plumes (examples

plots shown) showed that TSS reached +32 mg/L close to dredger and +5 mg/L 200 m down current

• TSS monitoring of 2003–2008 dredging

showed average TSS of 7.2 mg/L (range <3-18.6 mg/L)

• Monitoring range within the natural range

– 10.6-11.6 mg/L + 10mg/L spring tide

Water Clarity

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• Snapper is a key fish in the gulf, well studied

with data on distribution of eggs and larvae

• Eggs are tolerant of TSS*
• Snapper larvae are visual and selective

feeders (copepod nauplii). Larvae settle in estuarine areas (biogenic). 12 hr LC50 = 157

• r 2,020 mg/L (open or closed mouth stage
• f development)
• TSS >50 mg/L decrease larvae feeding rates.

Prediction of a “first observable effect” on larvae feeding at 4 or 150 mg/L (however, larvae still had yolk sack). Natural concentrations + dredging at lower end of predicted threshold

* Partridge & Michael (2010) Jnl. Fish Biology 77:227-240.

Impacts on Marine Life (benthic)

• verall)

)

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• Over the duration of dredging, a

patchwork loss of benthic fauna and recolonisation will occur

• Areas dredged early will be reforming

benthic assemblages during the dredging period

• Based on work undertaken up to

2013, the shelly areas dredged in 2004-2007 have reformed communities similar to those present before dredging started

• Effects of far-field sedimentation are

not expected as the areas (away from the channel) are depositional and muddy

Impacts on Marine Life (birds) )

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• A range of coastal birds use the lower harbour, Rangitoto

Channel and approaches

• This area is well traversed by ships, ferries and recreation craft
• Some species breed in proximity of channel (terns, gulls etc.)
• Some are surface feeders, others plunge divers (terns, gannets

etc.) feeding on baitfish, zooplankton etc.

• Some are local breeding, some visitors.
• Areas of turbid seawater are localised
• Noise in channel from dredging not considered to be

environmentally significant

Impacts on Environment (mammals) )

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• Marine mammals transit the Navigation Precinct.
• Marine mammal presence frequency is low.
• Higher for small mammals (dolphin species) but

very low for larger mammals (e.g. Bryde’s whale, Orca).

• Dredging undertaken while stationary (minimal

moving collision risk as vessel speeds are low).

• Same method of dredging has been carried out

without spotters for many years with no incidents.

• Spotters will be used during disposal at the CDS.
• Noise in channel from dredging minimal. Not

considered to be environmentally significant.

Impacts on Environment (biosecurity) )

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• Channel precinct is surveyed every six months.
• Extended sampling done for application.
• There are fewer invasive species within the channel

than in inshore/intertidal areas of the Waitematā.

• MPI reviewed biosecurity assessment (as part of

disposal application to EPA).

• Any factors that change species present/biosecurity risk

require reassessment and communication with EPA (Disposal condition).

• Re-assessment is required as part of each approved

sampling plan.

• MPI review every assessment and need to give their

approval.

Impacts on Environment (biosecurity)

Re-use of shell hash

• There are potential re-use options for shell

hash for biogenic habitat creation.

• The hash is intended for use primarily

within the Waitematā Harbour.

• Sabella (fan worm) is a notifiable organism

(Biosecurity Notifiable organism) order 2016).

• This controls the movement of shell hash
• ut of the Waitemata Harbour (Section 46
• f the Biosecurity Act).

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Duration of Consent )

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• Capital Dredging consent sought for 15 years
• Maintenance dredging to maintain new depths sought for 35 years
• Dredging only to be undertaken as needed.
• Staged to reduce impacts, cost and provide flexibility.
• Timed to meet expected deployment of larger ships to NZ market.
• Duration consistent with previous capital dredging consent.

Alternative Disposal Options

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• POAL has experience with dredge

material reuse (past 20 years)

• Successfully developed “mudcrete”

product used in Viaduct and Fergusson reclamations.

• Established Disposal Options Advisory

Group (DOAG) in 1990s.

• Involved wide variety of stakeholders.
• Canvassed all available options at the

time. DOAG Recommendations:

• Preferred option - use in land reclamation
• Second option – disposal in waters

deeper that 100m

Alternative Disposal Options

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• POAL reviewed options again for EPA

disposal application

• DOAG options still valid but along with

sea disposal POAL looking for alternatives

• Opportunities for reuse include:
• Reclamation (by others), marine

stabilisation, shore stabilisation, shore protection, land uplift (sea level rise), infill and ground engineering.

• Unsuitable material (for marine disposal)

can be mudcreted for infill or go to landfill.

• POAL discussing options with number
• f potential users

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Any new location will require major development with significant environmental impact:

• Dredging & disposal
• Reclamation and new berths
• New roads
• New rail
• New township & business park

around port Northport a particularly poor option:

• Too small to accommodate POAL’s

existing cargo streams

• 570 metre berth vs 3,000 metres
• Extensive development required in

harbour with high ecological value

• Remote location: very high carbon

footprint for transport of freight to Auckland ~10x existing emissions.

Dredging POAL (Mm3) Northport1

(Mm3)

Channel 2.25 3.7 Approaches / Berths 0.25 1.2 Maintenance Dredging 75,000 m3 over 5 years 120,000 m3

• ver 2 years

1 Preliminary volumes based on Refinery NZ channel deepening consent

and calculation of dredging required for existing Northport expansion plan.

Future Port Location

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• Current limit is lightly laden Suezmax – 275m long, 14.5m draft.
• Northport needs significant under keel clearance due to swells
• Northport’s website states ‘a few vessels have been loading to deeper drafts (approximately 14.5m /

14.7m) but have been waiting at anchor, sometimes up to a week for windows of opportunity based

• n favourable weather / swell conditions, before being able to berth’.
• 3.7 million m3 of dredging required for deeper draft Suezmax tankers to the Oil Refinery. Likely to

be >5 million m3 for Post Panamax containerships to Northport.

Northport / Marsden Refinery

Questions and Answers

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