Project DescriptionThe Panama Canal Expansion Project included the construction of four dams that will allow navigation access to the new Pacific Post-Panamax Locks. Borinquen Dams 1W, 2W & 2E are part of the design-build contract for the Third Set of Locks.

Challenges Faced During Construction: » Variable Geology » High Seismic Hazards » Challenging Foundation Conditions » Construction in Tropical Climate » Use of Tropical Residual Soils » Filters Optimization

Faults treatment » Four Major Fault Treatments Were

Implemented - Miraflores Fault - Dam 1W

- Miraflores Fault - Dam 2E

- Unnamed Fault (Dam 2W)

- Shear Zone at Sta. 0+590 (Dam 2W)

» Treatment Implemented - Seepage Cutoff Wall

- Upstream Clay Blanket

- Downstream Filter Blanket

Use of Tropical Residual Soils as Clay Core Materials » Two Main Sources of Materials

(Sucre and Cocolí Hill) » High Natural Moisture Content (30 to 45 %) » Natural Moisture Content +5 to +12 % above OMC. » Exhibits “Dry” Behavior at Optimum Moisture

Content » Materials Sensitive to Testing Procedures and Oven

Temperatures » Rainfall Precludes Drying of Borrow Areas

and Stockpiles » Remedial Actions:

- Special Placement and Compaction Controls Were Developed

- Extensive Laboratory Testing and Field Trials

- Acceptance Criteria Based on Degree of Saturation (S) in addition to MDD and OMC

- MDD and OMC Were Specified with Degree of Saturation to Prevent Compacting Materials Excessively Wet of optimum

Filters Optimization » Owner’s Conceptual Design Required Four

Different Filters Placed in Six Separate Zones » An Effort was Made by Designer to Reduce the

Numbers of Filter/Transition Zones Due to Material Availability and Construction Issues

» Final Filter Design in Accordance with U.S. Bureau of Reclamation Guidelines (USBR, 2007)

» As a Result One Broadly-graded Sand Filter/Transition Zone and a Graded Rockfill (i.e., “Buffer”) Adjacent to the Filters/Transitions were Implemented

» The Dams Included One Broadly-graded, Gravelly Sand Chimney Filter/Transition (Type 3a) at Both the Inboard and Outboard Sides of the Core and Cobble “Buffer” Material

Construction in Tropical Climate » High Temperatures and

Humidity » Abundant rainfall » Frequent Thunderstorms » Placement and Compaction

during Rainy Season » Remedial Actions

Implemented: - Flexibility in Construction Sequence

- Execution of Construction Joints Perpendicular to the Dam Axis

- Advanced Construction of Rock Fill Shells placed on the Inboard and Outboard Toe of the Dam

- Core Geometry was Revised From Conceptual Design to Reduce the Quantity of Clay Materials and Excavations

Wonnie Kim, PE – MWH Gabriel Martinez – MWH Carlos Zambrano, PE – MWHwww.mwhglobal.com

General Foundation Conditions Conditions Faced During ConstructionThree Different

Geological Formations » Basalt Formation » La Boca Formation » Pedro Miguel Formation

Presence of Active Faults » Pedro Miguel Fault » Miraflores Fault » Unnamed Fault

Seepage Control » Double Grout Curtain

Seismic Considerations (Owner’s Requirement)

» Horizontal Displacements Up to 3.0 m » Vertical Displacements Up to 0.50 m » Two Design Earthquakes (1000 & 2500

return periods) » Peak Ground Accelerations 0.72g & 0.97g

DAM FEATURES

Dam Type Zoned rockfill dam with central clay core

Crest Elevation (without camber) El. 32 m PLD

Top of Core Elevation (without camber) El. 29 m PLD

Crest Width 30 m

Max. Dam Height (above foundation) 35 m

Dam Length 0.6 km (1W), 0.9 km (2W), 1.4 km (2E)

Dam Fill Volume 7 million m3 (approx.)

Dam/Core Freeboard (above NMOP) 4.87 m / 1.87 m

Inboard Slopes 2.87H:1V

Outboard Slopes 2.5H:1V (1W & 2W), 2.5H:1V to 3H:1V (2E)

Design-Build Construction of the Panama Canal Borinquen Dams 1W, 2W and 2E

Typical Foundation Treatment Implemented in Major Faults/Sheared Zones Borrow Source

Compaction Requirements Shear Strength RequirementMoisture Content Density / Saturation Level

Sucre Hill

+1% to +4% OMC 98% of MDD (avg.) 96% of MDD (min.) n/a

+4 to +10% OMCDensity equivalent to

87% (min.) and 90% (avg.) saturation

70 kPa (shear vane)

Cocoli Hill

+1% to +4% OMC 98% of MDD (average) 96% of MDD (minimum) n/a

+4 to +8% OMC Density equivalent to 90% (min.) saturation 120 kPa (shear vane)

Borinquen Dams 1W, 2W & 2E Typical Cross Section

Panama Canal Expansion Project Pacific Site - Borinquen Dams 1W, 2W & 2E Panama Canal Expansion Project Pacific Site – General Geological Conditions

Borinquen Dam 1W – Basalt FormationTypical Foundation Conditions

Borinquen Dam 2W – La Boca FormationTypical Foundation Conditions

Typical Material Condition at Moisture Content +3% above OMC

Filter and Buffer Material Placement

Sucre Hill and Cocolí Hill End-Production Compaction Specifications

Panama Canal Expansion Project General Layout