Greystones Harbour – Civil and Maritime Works
Sean Mason, FIEI
2nd May 2013
Contents 1. 2. 3. 4. 5. Images from 1996
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Contents
History Bid Stage Preferred Bidder Stage Detailed Design Stage Construction Stage
Location
Dublin Greystones
• Design life: 100 years • MHWS/MLWS: 1.5m / -1.5 m OD Malin • Climate change: +0.9 m in 100 years • 100 year return period at 2015 +2.5m OD Malin . Hmo = 4.7 m . Tp = 10.7 s
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History
Victorian Times
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History
Developments • Quay Wall Extension • Kish Base • Northern Breakwater
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History
Coastline
Problems Coastal Erosion
Storm Damage
Old Landfill
1.
Siltation of Harbour
2.
Damage to Breakwaters
3.
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Coastal Erosion
Storm Damage
Harbour Siltation
Siltation of Harbour
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History
Damage to Breakwater
• Collapse of Structures • Cavities within Breakwater • Remedial Works
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History
Coastal Erosion – Railway • Route Selection – Earl of Meath • Isombard Kingdom Brunel • Bray Head – PreCambrian rocks • Tunnels and Bridges
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History
Coastal Erosion – Railway
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History
Coastal Erosion – Railway
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History
Coastal Erosion – Cliffs • • • •
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Dynamic Coastal ‘Cell’ Erosion Process – waves Erosion Process – rainfall 0.5m/year average retreat
History
[Pictures]
Coastal Erosion – Storm Events • 1929/31 Storms • Houses Lost • Coastal Defences destroyed
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History
The Power of the Sea [Video Clip]
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History
The Power of the Sea
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History
Bid Stage • 1999 - Greystones (and Delgany) Local Area Plan designated site for new Harbour/Marina. make safe and restore existing harbour,
Address coastal erosion, and; provide new major public amenity. • 2001 – Wicklow County Council decision to procure through a PPP model. 230 Berth Marina 360 Residential Units 6,000m² Commercial 16 acre public park Public Harbour, Public Square Coastal Protection Works 16
Bid Stage
Public Private Procurement (PPP) Model • 30 year concession period – Design, Construction and Operation • Award of Preferred Bidder status preplanning • EU Public Procurement • WCC provide land, concessionaire provides public amenities • Hand-back to WCC all public space • Significant new facilities for local clubs
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Bid Stage
Ground Conditions • • • •
Desk Study Ground Investigations Ground Model Made Ground
+10m OD Malin
Laminated Fluvioglacial Sands & Gravels
Beach Shingle 0m OD Malin
-6m OD Malin Brown Boulder Clays varies
Greywacke Bedrock 18
Bid Stage
Reference Design and Outline EIS • • • • •
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Refurbished Harbour New Marina Landslide Development Public Amenities Coastal Protection
Bid Stage
Bid Design - Layout • Minimizing cut and fill
• Buildings more protected Coastal protection 02 Marina 03 North breakwater 04 Harbour 05 South breakwater 06 Public slipway 07 Coastguard
08 Yacht clubs
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Bid Stage
Bid Design – Harbour Entrance • •
Simplify geometry (cost) Retain dynamic ‘spending’ beach
Reference design N
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Bid Stage
Bid design
Wave disturbance in the harbour (1-year storm)
Bid Design – Breakwaters • Height and Width constraints • Structure options: Embankment Sheet-piled Cofferdam Precast Caisson (marine access) Precast Block • Seaward Revetment
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Bid Stage
Coastal Protection Existing Situation Scheme Objectives: • Protect landfill and heritage area • Preserve coastal cliff walk • Overall scheme should preserve or enhance amenity value and minimise adverse environmental impact Key Constraint Avoid increased erosion of coastline to north of scheme.
Assumes no interventions to existing coastline
Existing cliff top
Existing beach
Perspective View
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Bid Stage
Elevation
NTS
Section 1
Coastal Protection Reference Design
Section 1
New cliff top
Engineered slope
Perspective View
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Bid Stage
Elevation
Rock Revetment
• Highly engineered approach to halt natural process over only part of north beach • Significantly increased erosion forecast over northern section threatening railway and impacting on cliff walk • Complete loss of much of north beach and replacement with an unsightly and inaccessible shoreline, with loss of amenity, natural cliffs and bird habitat • Safety issue with regard to access over and around revetments • Given uncertainty in future maritime conditions a highly engineered approach is not sensible as there is no flexibility in the solution
Coastal Protection Design Development • Solution is to work with nature rather than against it • Managed Retreat solution • More sustainable solution for entire north beach • Landfill protected with revetment and groynes to create recreational beach area • Single beach replenishment will supply material to the coastal system, reducing erosion behind berm and to lesser extent to the north by gradual shingle spread • Existing north beach amenity preserved in its entirety • Subject to detailed design and modelling off shore ‘reefs’ may be added to further reduce erosion over area protected. • Reefs may be visually intrusive at low tide and potential safety issue
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Bid Stage
Section 1 Showing Beach Replenishment Only
Section 1 Showing Optional Reefs
Coastal Protection Design Development
Existing cliff top
Shingle beach
A: Perspective View Showing Beach Replenishment Only
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Bid Stage
A: Elevation Showing Beach Replenishment Only
DO NOTHING
Railway
Archaeological Site
Landfill site
MANAGED RETREAT
HOLD THE LINE
Proposed Coastal Protection strategy
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Bid Stage
Preferred Bidder Stage • Preliminary Design and EIA
• Planning Process • Stakeholder Management • Contractor Input
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Preferred Bidder Stage
Preliminary Design and EIA • Traffic and Access (Batching Plant) • Protected Views • Ecology (sand-martins and sea-kale) • Archaeology (St. Crispin’s Cell and Rathdown Castle) • Coastal Erosion • Old Landfill • Flooding
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Preferred Bidder Stage
Planning Process • WCC application to ABP • CPO included in application • Foreshore Acquisition included, Foreshore Lease/License not required • Dredging and reclamation included in application • Oral Hearing in March/April 2006 • Request for Further Information in August 2006. Submitted in October 2006 • 2nd Oral Hearing in March/April 2007 • Planning Granted in August 2007 31
Preferred Bidder Stage
Stakeholder Management – Harbour users • OPW Coastguard Facilities • Greystones Sailing Club (HUGs) • Greystones Rowing Club • Sea Scouts • Ridge Anglers • Diving Club • Moorings Licences • Public (adjoining residents, local area, wider community)
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Preferred Bidder Stage
Stakeholder Management • Harbour residents with real impacts • Resistance to change – ‘Victorian Feel’ • Giving Public Amenity to Private Interests • GPDA: Greystones Protection and Development Association
• GUBOH: Give Us Back Our Harbour (twitter @guboh)
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Preferred Bidder Stage
Contractor Input • Construction Methodology (by land) • Programme • Participation in Planning Process • Value Engineering
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Preferred Bidder Stage
Borrow Pit • Materials Balance • Economics of handling/processing • Granted as part of the planning permission
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Preferred Bidder Stage
Detailed Design • Planning permission granted August 2007
• Concession Agreement signed December 2007 • Detailed Design: Breakwater Structures Harbour & Marina
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Detailed Design Stage
Design risk: 1. Limited modelling for reference design
2. Hand calculations & limited modelling for bid design
3. Numerical modelling completed 4. Physical modelling (in progress when application made)
5. Hand calculations for revised layout
Bid stage
Planning stage
Detailed design stage
Detailed Design • Sispar appointed Sisk – Lagan JV for ‘Civil and Marine Works Contract’ • Fixed Price D&B Contract (largely designed already) • Arup both Employer’s (Sispar) Representative and Contractor (SLJV) designer!
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Detailed Design Stage
Breakwaters - Stability • Design for sliding, overturning, settlement
• Granular (porous) base – Goda Equations • ‘Free standing’ Stacks to take out differential settlements • Grout ‘socks’ with in-situ slab
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Detailed Design Stage
Breakwaters – Physical Modelling • DHI Copenhagen
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Detailed Design Stage
Flume Tests on Breakwater and Revetment
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Detailed Design Stage
Design Wave Conditions
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Detailed Design Stage
Scale Model Testing
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Detailed Design Stage
Harbour Entrance • Reflected waves – turbulence and water depth • ‘Porous’ roundheads • Uplift pressures – anchor piles Wave disturbance in the harbour: A solid vs a porous harbour entrance
Difference compared to original design
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Detailed Design Stage
Harbour/Marina Wave Climate • Seiching (reflected standing wave) within Marina
• Sloped revetments around Marina under boardwalk
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Detailed Design Stage
Breakwater – Design Development • Breakwater crest height • Curved seaward – facing wave-wall • Wider base blocks (with voids to manage weight) • Antifer sizes and underlying rock fill sizes
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Detailed Design Stage
Breakwater Layout
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Detailed Design Stage
Civil & Marine Works Contract • Contract signed between Sispar and SLJV
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Construction Stage
Construction Stage • Demolitions
• Batching Plant • Breakwater Construction • Dredging and Reclamation • Piling Works • Old Landfill • Beaches and Erosion Protection • Value Engineering • Statistics
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Construction Stage
Demolitions • Pier, Kish base, north breakwater • Gap Bridge (cut-stone retained)
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Construction Stage
Batching Plant (S.M. Morris) • Agreed early and part of planning as Contractor onboard • Flexibility in materials (concrete) delivery to site • Tolerance on 5m x 3m x 1m blocks of 1mm • Maximised design using pre-cast elements • Continuous environmental monitoring
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Construction Stage
Breakwater Construction Plan • General Approach – land based operation • Temporary Causeway to allow breakwater construction on 3 fronts • Bed preparation using frames (minimize divers required) • Work out with block stacks, return with slab
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Construction Stage
Breakwater Settlement
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Construction Stage
Breakwater Construction - Reality • Issue with leading edge of Temporary Causeway
• Bed preparation – levelling frame and divers • Vulnerability of ‘free-standing’ stacks
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Construction Stage
Storm Damage • September 2008 • Gusting Force 9 gale • Significant damage over 9 rows of blocks • Temporary support to stacks inadequate • Scour protection around base inadequate
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Construction Stage
‌ the day after
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Construction Stage
North breakwater
South Breakwater 57
Construction Stage
Storm Protection • Timber spacer blocks • End-frame • Levelling Frame for 6 stacks • Scour protection slabs • Revetment as close as deemed safe behind
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Construction Stage
Breakwater Tolerances • • • • •
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Diver checked formations Precise levelling of bed Diver assisted crane placement of blocks Very tight tolerances on block placement Visual impact (client and architect)
Dredging • Need for floating plant • Temporary load-out quay • Hopper barges for transfer • Machine excavation of boulder clay (GPS on bucket)
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Construction Stage
Reclamation • Granular below MHWL, cohesive (boulder clays) above
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Construction Stage
Borrow Pit 62
Landside Earthworks • Marine Works delay impact on sequencing • Compaction of fill • Use of lime on wet • boulder clays
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Construction Stage
Piling Works • Tubular Steel Piles • Driven to set (+ minimum penetration) • Hydraulic Hammer • Anticipate Driven Precast Piles for buildings
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Construction Stage
Piling Works
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Construction Stage
Old Landfill • No CH4, traces CO2, granular curtain • Above water table with porous capping – all mobile containments longsince leached to sea • Risk Assessment to leave in-situ as parkland • Approved by WCC and ABP
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Construction Stage
Old Landfill
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Construction Stage
Beaches and Erosion • Where reclaimed, shingle removed for re-use • 10,000m3 imported shingle at start of construction • Predicted movement pattern
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Construction Stage
Beaches and Erosion • Observed pattern during construction • 6,000m3 accreted shingle relocated in 2009 • 4,500m3 accreted shingle relocated in 2012
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Construction Stage
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Construction Stage
Value Engineering Porous Roundheads
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Construction Stage
Value Engineering Porous Roundheads
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Construction Stage
Precast Recurve Wall
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Construction Stage
March 2009 74
Construction Stage
22 January 2010 75
Construction Stage
26 March 2010 76
Construction Stage
13 May 2010 77
Construction Stage
13 May 2010 78
Construction Stage
23 July 2010 79
Construction Stage
22 September 2010
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Construction Stage
22 September 2010 81
Construction Stage
18 January 2011 82
Construction Stage
Statistics • Concrete Volume 125,000 cu meters, greater than Dundrum SC
• 5,100 breakwater blocks • 3,900 antifers • 90,000 tons of 3-6 ton imported rock armour • 115,000 cu metres dredging /excavation • 203,000 cu metres reclamation fill • Contract Value approx. €50m, €1m over tender • Total spend on development to date circa €70million
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Construction Stage
Construction Completion Civil & Marine Works contract Started March 2008 Completed Feb 2011
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Construction Stage
Acknowledgements • Wicklow County Council – Sean Quirke • Employer’s Rep Jacobs (now Leigh Fisher) • Sispar – John Sisks & Park Developments • Sisk Lagan JV (and subcontractors) • Design Team (OMP, Broadway Malyan, Terry Durney) • Subconsultants (COWI, DHI) • Arup Staff (office and site) • Greystones Public Representatives • Greystones people • Jimmy Quinn photography and Derek Paine books 85
Acknowledgements
Thank You
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Thank You