Update 17 December 2019 Waimea Water 17/12/2019 Waimea Water Ltd - - PowerPoint PPT Presentation

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Update 17 December 2019 Waimea Water 17/12/2019 Waimea Water Ltd - - PowerPoint PPT Presentation

Jan 24, 2023 188 likes •395 views

Waimea Community Dam Update 17 December 2019 Waimea Water 17/12/2019 Waimea Water Ltd 1 Agenda Design Construction Environmental 2009: 5-9 2012: 10-14 Cost and schedule 2017: 15-17 17/12/2019 Waimea Water Ltd 2 Waimea

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SLIDE 1

Waimea Community Dam Update

17 December 2019

Waimea Water

Waimea Water Ltd 17/12/2019 1

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SLIDE 2

Agenda

  • Design
  • Construction
  • Environmental
  • Cost and schedule

Waimea Water Ltd 2

2009: 5-9 2012: 10-14 2017: 15-17

17/12/2019

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SLIDE 3

Waimea Dam is underway and progressing well

Ground Breaking Ceremony 9 August 2019

Waimea Water Ltd 3 17/12/2019

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SLIDE 4

Design Update

  • Rezoning: Flexibility / robustness to geology
  • Spillway: De-risk construction, topography
  • Plinth: Optimised. Updated grout curtain
  • Membrane: Enhance resilience. Savings
  • MechElect: Progressing optimised design.
  • Bridges: Remove upper-spillway. Savings

Waimea Water Ltd 4

2009: 5-9 2012: 10-14 2017: 15-17

17/12/2019

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SLIDE 5

Design: Rezoning embankment to manage geology

❖ Expect less harder class-1 material ❖ Experiencing more fines  Increase drainage layers with  Processed (screened) out fines

Waimea Water Ltd 5

2009: 5-9 2012: 10-14 2017: 15-17

17/12/2019

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SLIDE 6

Design: Geosynthetic membrane

Considering replacing concrete face with Geosynthetic membrane  Improved resilience to settlement and seismic (elasticity)  Cost and schedule savings  CO2 reductions  Performance warranty Carpi Ltd: Installed

  • 54 New Dams since 1988 (26 larger than Waimea)
  • 142 Retrofitted Dams since 1970 (63 since 2010)

Waimea Water Ltd 6

2009: 5-9 2012: 10-14 2017: 15-17

17/12/2019

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SLIDE 7

Design: Mechanical design completed

  • Low and mid-level GRP draw off

Water quality and temp control

  • Single pipe through 160 m culvert
  • 3 nozzles at outlet

Environmental to flushing flows

  • Powergen compatible

Waimea Water Ltd 7

2009: 5-9 2012: 10-14 2017: 15-17

17/12/2019

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SLIDE 8

Construction: Proceeding as planned

Waimea Water Ltd 8 17/12/2019

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SLIDE 9

Construction: Culvert Construction

▪ ~80/160m of culvert cut excavated and pouring blinding concrete poured to 60/160m ▪ Construction of 160m long 5x4m culvert commenced Nov-2019. Poured 2 X 10m floor sections ▪ Divert river May-2020. Exploring options to expedite

Waimea Water Ltd 9 17/12/2019

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SLIDE 10

Construction: Preparing for LHS Plinth. As expected

Waimea Water Ltd 10 17/12/2019

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SLIDE 11

Construction: Clearing RHS Abutment. As expected

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SLIDE 12

Construction: Permanent Slope Protection progressing

Waimea Water Ltd 12 17/12/2019

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SLIDE 13

Construction: Flood risk is very real

Waimea Water Ltd 13 02/12/2019

Flood Level

2 December: 102 m3/s (1:50 = 250 m3/s; 12 May 2019)

  • Temporary works designed to overtop

➢Cofferdam protecting embankment ➢Downstream reinforced mesh dam

  • Expect >8 flood events
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SLIDE 14

Environment and Sustainability

  • 164 Resource Consent conditions; Working 99 action items
  • Biodiversity Management Plan approved with 8 plans. BTAG

Onsite

  • 7/9 SCEMPS approved, implemented and being monitored
  • 6 Sediment Retention Ponds & 7 Decanting Bunds operating
  • Hydroseeding & mulching mitigates erosion and sedimentation
  • Fortnightly independent water quality monitoring complies
  • Continuous turbidity monitors guides river works
  • 3/4 rare plant species removed for propagation (BMP #2)

Offsite

  • Ordered 11,000 plants and weed control for Rough Island

Waimea Water Ltd 14 17/12/2019

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SLIDE 15

~ 2months behind; seeking opportunities to recover

Waimea Water Ltd 15 17/12/2019

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SLIDE 16

Funding and expenditure

Waimea Water Ltd 16

Funding and Spend Forecast cost & schedule to complete Spent $32m $6m behind Spent $32m $6m behind

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SLIDE 17

Waimea Water Ltd 17

Risk Management: 22% of Project Budget at Risk

Managing key risks

Risk Heat Map

High Risks:

  • Rock fill into embankment
  • Grout subsurface
  • Topography on Spillway
  • Slope stability
  • M & E Design
Very Low Low Medium High Very High Very High
  • 1 - - -
High

1 3 3 6 -

Medium

1 4 6 3 1

Low
  • 1 3 - -
Very Low
  • - - 1 -
Very Low Low Medium High Very High

Threat Likelihood

Mitigating Actions: ➢ Rezoning, trials, bores ➢ New grout & plinth design ➢ Spillway design ➢ Assessing ➢ Optimising (1 pipe)

17/12/2019

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SLIDE 18

More Information

Waimea Water Ltd 18 17/12/2019

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SLIDE 19

Waimea Water Ltd

Questions?

Waimea Water Ltd 19

➢ ~ 2 months behind with late start: Pursuing opportunities to recover ➢ So far, have not encountered anything that exceeds funding envelope

BUT (health warning)

➢ Early days, and significant geological and topographical risks exist ➢ Expect to have better understanding on cost & schedule mid-2020

17/12/2019

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SLIDE 20

Design: Highest category (NZSOLD / ANCOLD / ICOLD)

▪ Concrete Faced Rockfill Dam; most robust to seismic loads and uses indigenous material ▪ 13 Mm3 (13 billion litre) reservoir; 53m high; 220m crest length; 430,000 m3 rock ▪ Earthquake: Operating basis 1:150 AEP (years); Seismic evaluation basis 1:10,000 AEP (years) ▪ Flood: Probable max: 1094 m3/s (100 yr 375 m3/s). 12 May 2019 1:50 year 250 m3/s (47 mm/hr)

Waimea Water Ltd 20

Turitea Concrete Faced Rockfill dam. Palmerston North Constructed 1907, 1912, 1996 3-D model overlaying existing site topography

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