Waimea Community Dam TDC Council...Construction Update: Spillway Waimea Water Ltd 24 Spillway cut...

Waimea Community DamTDC Council

25 June 2020

Waimea Water

Waimea Water Ltd25/06/2020 1

Agenda

1. Covid-19 impact

2. Funding and expenditure

3. Expenditure and progress

4. Safety

5. Environmental

6. Rockfill: The geology challenge

7. Design update

8. Construction update (video)

9. Questions

Waimea Water Ltd 225/06/2020

Meet the WWL Team

Waimea Water Ltd 3

• Designer (PS-1, PS-4) Damwatch Engineering

• Reviewer (PS-2) GHD Engineering

• Engineer to Contract Stantec

• Contractor (PS-3) Fulton Hogan Taylors

• Quantity Surveyor Rawlinsons

• Contract Law Anderson Lloyd

• Programme CCCL

• Safety Impac; Intesafety

• Accountant Findex

• Banker ANZ

• Auditor Audit NZ

25/06/2020

COVID-19❖ WWL incurs cost of 5-week Suspension and further delay (no Force Majeure provision in NZ3910)

➢ Further week delay to remobilize and implement facilities

➢ Not covered by insurance

❖ Productivity impacted on resumption with level-3 / level-2 protocols

➢ NZ Construction Industry Standards

❖ Supply chain constrained and likely to slow project: Spares, parts, equipment

➢ Uncertain how international supply chain recovers

❖ Cost of suspension and recovery to yet be determined

➢ Looking to NZ Construction Industry. No precedents

➢ Impact of COVID-19 to be determined during 2020/21 year per Final SOI


-

20

40

60

80

100

120

140

Dec-2018 Dec-2019 Dec-2020 Dec-2021

$ m

illio

ns

Budget New forecast (SoI) Actual

Funding and expenditure: 31 May 2020

Waimea Water Ltd 5

Funding and Spend Forecast cost & schedule to complete

$50.2m

Excludes Cost of COVID-19$129.4m

July 2020

August 2021

25/06/2020

0% 25% 50% 75% 100%

$

Months

ECI Costs During Construction Construction Variations Remain Original Budget Revised Forecast

$104.4m $129.4m

40mths37mths

Expenditure and progress

Waimea Water Ltd 6

Expenditure

Progress

$50m

16 months

Excludes Cost of COVID-19

25/06/2020

Context (SOI)

Waimea Water Ltd 7

Excludes Cost of COVID-19

25/06/2020

Programme: + 6 months = +1 season


❖ Currently expect 6 month delay to programme with further risk of slippage

❖ Exploring and pursuing recovery programme (shift work; defer works)

Safety: No injuries to date

Celebrating 500 days injury free

Waimea Water Ltd 9

Leading: Contractor Audit and Inspection

0

5

10

15

20

25

30

35

Jun-19 Jul-19 Aug-19 Sep-19 Oct-19 Nov-19 Dec-19 Jan-20 Feb-20 Mar-20 Apr-20 May-20

Lead OFI Low Potential Med Potential High Potential

0

1

0

1

2

3

4

5

Inci

de

nt

Fre

qu

en

cy r

atio

sLT

IFR

/ M

TIFR

/ T

RIF

R

Nu

mb

er

of

inci

de

nts

LTI

MTI

FAI

HPI

MTIFR

TRIFR

Lagging: Accidents, Harm, HPI

25/06/2020

Environmental: Full compliance with consent

Waimea Water Ltd 10

Lead: Audit, Inspection and Water Quality monitoring

25/06/2020

0

2

4

6

8

10

12

14

Apr-19 May-19 Jun-19 Jul-19 Aug-19 Sep-19 Oct-19 Nov-19 Dec-19 Jan-20 Feb-20 Mar-20 Apr-20 May-20 Jun-20

No

. Au

dit

s p

er m

on

th

TDC Compliance Contractor Weekly Audit Contractor Monthly Audit

FHTJV HO Env Visit Environmental Control Inspection Environmental Follow Up Audit

Southern Skies ESC Inspection SLR Water Quality Visit

#42 River Health Indicator: Quantitative Macroinvertebrate Community Index

• Approved 5 Environmental Management Plans

✓ Verified

• Approved 9 SCEMPs

✓ Verified

All required plans for current works in place, certified, verified and functioning

5

5.5

6

6.5

7

7.5

8

8.5

6/03/2017 22/09/2017 10/04/2018 27/10/2018 15/05/2019 1/12/2019

QM

CI I

nd

ex (

clip

ped

to

sh

ow

d

etai

l)

QMCI Upstream

QMCI Downstream

20% below averagepre-constructionU/S QMCI

During ConstructionPre- Construction

Environmental: Full compliance with consent

Waimea Water Ltd 11

#45 River Health Indicator: pH

#44 River Health Indicator: Deposited Fine Sediment

25/06/2020

Independent ecologist verifies river health indicators

0

2

4

6

8

10

12

pH

pH Upstream

pH Downstream

Lower Limit

Upper Limit

0

5

10

15

20

25

30

35

40

45

50

% o

f ri

ver

bed

wit

h f

ine

sed

imen

t d

epo

sits

Upstream

Downstream

Downstream Threshold

Rockfill: The Geology Challenge

Waimea Water Ltd 12

▪ Embankment trials late December 2019 and early January 2020 identified Rock degradation

Heavily broken down– Not free drainingLess broken down– Free draining

Expected and Needed Discovered

25/06/2020

Rockfill: The Geology Challenge

Waimea Water Ltd 13

▪ Discovering more argillite (mud / siltstone) (~70%) and less greywacke (sandstone) than expected

▪ Greywacke (sandstone) dispersed amongst predominant argillite. Difficult to salvage. (VIDEO)

▪ Fissile argillite showing tendency to break along insipient foliations

➢ Spillway Excavation: “May yield a minimum of 350,000 m3 of rock that will consist of slightly weathered to weathered (Class 1 & 2) greywacke.” (2014). Predominantly fissile argillite

➢ Need to find suitable drainage material from alternative sources (cost)

25/06/2020

Design: Rezoning embankment to manage geology❖ Expect less harder class-1 material

❖ Testing in early 2020 identified breakdown on compaction

Increase drainage layers

Alternatively source drainage rock

Waimea Water Ltd 14

Free Draining

Not Free Draining

Drainage

25/06/2020

Design: Spillway modified for improved resilience

Waimea Water Ltd 15

2009: 5-92012: 10-142017: 15-17

Design modifications due to recent learnings from international spillway incidents (international standards)

Oroville (right) failure due to poor drainage and anchoring detailing (pressure beneath fn velocity)

Whaley Bridge (UK) no drainage and poor slab detailing combined with poor maintenance

Modifications for resilience (requested by CIIL):

Drainage reviewed and upgraded

Anchoring design reviewed and upgraded

Additional modifications driven by topography and encountered geology.

25/06/2020

Design Update

✓ Spillway:

▪ Redesigned with vertical walls to mitigate topography / geology risks RHS

▪ Increased drainage per recent standard

▪ Completed and peer reviewed


Design Update: Other items

Mechanical and Electrical

❖ Not designed or priced at commencement of work

Provision Sum challenged

To be priced ~3rd Quarter 2020

▪ Progressing detailed design

Switch to single outlet pipe aiming to realise cost savings

Modifications for future hydropower installation

Waimea Water Ltd 17

2009: 5-92012: 10-142017: 15-17

25/06/2020

Power Generation: Opportunity

Enlarge Reservoir / Powergen

▪ Fuse Gate to utilise 2.3m / 5m of flood reservoir

▪ Activate in event of large flood say 1:10,000 yr AEP(55% - 70% of PMF 1094 m3/s)

▪ + 1.5Mm3 storage to ~15Mm3 (15%)

Storage increases powergen utilisation

Increase resilience to droughts / growth / demand


Agenda

1. Covid-19 impact

2. Funding and expenditure

3. Expenditure and progress

4. Safety

5. Environmental

6. Rockfill: The geology challenge

7. Design update

8. Construction update (video)

9. Questions


Construction Update

Waimea Water Ltd 20

LHS Plinth

Culvert

RHS Plinth

Spillway

25/06/2020

Diversion Culvert: ~80% complete

Waimea Water Ltd 21

✓ Completed Floor

✓ 12/17 wall & roof sections completed

➢ Expect to complete by Aug and divert river September 2020

25/06/2020

Construction Update: Forming LHS Plinth

Waimea Water Ltd 22

✓ Foundation treated and site blinding concrete complete

✓ Commenced forming plinth

25/06/2020

Construction Update: Preparing RHS Plinth

Waimea Water Ltd 23

✓ Foundation treatment and treatment underway

25/06/2020

Construction Update: Spillway

Waimea Water Ltd 24

▪ Spillway cut underway

➢ Exposed first 20 m section of foundation

❖ Uncovering significantly weathered foundation that will require treatment

▪ Close to cliff edge

✓ Supports change in design to self-supporting vertical walls, rather than a liner

▪ Will evaluate extent of any edge support

25/06/2020

Construction Issues: Unexpected Voids


❖ >1000 m3 concrete

✓ LHS & Culvert done

❖ RHS, Spillway and starter dam to do

Closing: By the numbers


Task Total Quantity Unit

Vegetation Clearance 85 Hectare

Excavation 633,000 m3

Fill 430,000 m3

Cut to Waste 311,000 m3

Material Processing 120,000 m3

Concrete 22,000 m3

Reo Steel (bars) 3,900 t

Reo Steel (mesh) 10,000 m2

Anchors 4,200 No.

Concrete Face 10,000 m2

More Information


https://www.google.com/imgres?imgurl=https%3A%2F%2Fwww.facebook.com%2Fimages%2Ffb_icon_325x325.png&imgrefurl=https%3A%2F%2Fwww.facebook.com%2F&docid=QanOc4elti2_UM&tbnid=eSZWZPUruLZj3M%3A&vet=10ahUKEwjQgNWZ-dblAhUz6XMBHaOLCVMQMwh1KAAwAA..i&w=325&h=325&itg=1&bih=967&biw=1920&q=facebook&ved=0ahUKEwjQgNWZ-dblAhUz6XMBHaOLCVMQMwh1KAAwAA&iact=mrc&uact=8

17 Dec 2019: 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 28

2009: 5-92012: 10-142017: 15-17

02/12/2019

Design: Geosynthetic membraneReplace concrete face with Geosynthetic membrane

Improved resilience to settlement and seismic(elasticity), benefit accentuated by softer rock

CO2, Cost and Schedule savings

Easy to repair; performance warranty

Testing demonstrates expected life 50-100 years (robust to UV)

Meets EU and International standards for Health and Environmental impacts

Carpi Ltd: Installed

• 54 New Dams since 1988 (26 larger than Waimea)

• 142 Retrofitted Dams since 1970 (63 since 2010)

• Used on Tekapo Canals (2013 / 2014)

Waimea Water Ltd 29

2009: 5-92012: 10-142017: 15-17

25/06/2020

Waimea Community Dam TDC Council...Construction Update: Spillway Waimea Water Ltd 24 Spillway cut...

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