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Construction Flood Risk Strategies for Dam Replacements
Tiffany Wong and David Oram
Parks Canada Infrastructure Directorate, Public Services and Procurement Canada
The objective of this presentation is to describe the construction flood risk mitigation strategies employed at three dam replacement sites on the Trent-Severn Waterway: Dam at Lock 23 – Otonabee Dam (DL23); Dam at Lock 24 – Douro Dam (DL24); and, Dam at Lock 25 – Sawers Creek Dam (DL25).
Abstract

During the project development stage, the risk of site inundation was accepted at all three dam replacement projects after considering financial and schedule implications of additional phasing. Planned inundation was incorporated into overall construction execution considering the seasonality of flood events. While the design and operational constraints are nearly identical for the three dams, distinct construction, flood risk management and contract management methodologies were utilized for each, stemming from individual hydraulic assessment findings, site-specific phasing and by-pass strategies. This presentation will provide an overview of the hydraulic studies, project planning, as well as overall project outcomes of restricting construction during high-risk phase, versus permitting passage of floods during construction.

During the freshet in 2019, the flooding risk was realized specifically at Douro Dam. The site flood management plan was enacted, construction area was evacuated and prepared for inundation, and cofferdam was breached in a controlled manner. This presentation further describes the breach execution strategies and procurement approaches that were applied which aided in the management of costs and schedule during the breach and construction recovery period.

Tiffany Wong, Senior Project Manager, Parks Canada Infrastructure Directorate, Public Services and Procurement Canada
Tiffany Wong, B.Eng., P.Eng., is a registered professional engineer in the province of Ontario and a senior project manager for the Parks Canada Infrastructure Directorate (PCI) of Public Services and Procurement Canada (PSPC). With PSPC since 2016, Tiffany’s principle role has been overseeing and delivering large-scale construction projects on behalf of various government departments including Parks Canada Agency, Department of National Defence, Fisheries and Oceans Canada, and Transport Canada. Prior to joining PSPC, since 2008, Tiffany worked in the energy industry developing and delivering significant demolition, environmental remediation, and capital projects.

 

Challenges in Urban Setting Waterway Construction Projects
Sarah Davidson and Fariborz Hashemian
Parks Canada Infrastructure Directorate, Public Services and Procurement Canada
The objective of this presentation is to demonstrate how careful planning, communication, commitment and pro-activeness must prevail for the successful completion of the waterway project on a UNESCO World Heritage Site.
Abstract

Careful planning and mindful management of numerous considerations are required even in initially envisioned non-complex civil engineering waterway projects: example of replacement of Rideau Canal concrete walls in Ottawa, Ontario.

The removal and replacement of 300 m long section of concrete walls lining a navigational canal would, at first, seem to be a project of relatively low complexity and risk. However, the addition of spatial constrained work area, contaminated canal bottom sediments (heavy metals and PAHs), varying geotechnical conditions, varying seasonal water levels, coffer-damming and dewatering difficulties, adjacent roadway shoring, traffic and pedestrian/cyclist management planning, nearby residential properties sensitive to noise and vibration, adjacent seasonal skateway and navigation period requirements, cold-to-hot weather conditions, fisheries window of no in-water work, as well as other competing construction contracts in close proximity provides for a mix of interesting and challenging scenarios and circumstances for enabling a simple canal wall replacement project in a busy urban environment of limited space and numerous constraints including stakeholder schedule expectations.

Sarah Davidson, Deputy Project Manager, Parks Canada Infrastructure Directorate, Public Services and Procurement Canada
Sarah Davidson holds a Bachelor of Applied Science from Queen’s University in Civil Engineering, and a Master of Infrastructure Protection and International Security from Carleton University. Sarah joined the Public Services and Procurement Canada (PSPC), Parks Canada Infrastructure Directorate, as a Deputy Project Manager in January 2017. Her previous government experience includes working as a Strategic Initiatives Project Officer in the Real Property Bureau of Global Affairs Canada, and as a Security Officer for the Department of Fisheries and Oceans.

 

Forecasting Squat of Post Panamax Container Ships in PortMiami’s Entrance Channel
Doug Scott, Wim van der Molen, Gordon Thompson
W. F. Baird & Associates Coastal Engineers Ltd.
The objective of this presentation is to demonstrate the utility of a new underkeel clearance forecasting tool to minimize the risk of bottom touching for Post-Panamax container ships.
Abstract

After the commissioning of the new locks in the Panama Canal in June 2016, more and larger Post Panamax container ships have visited the main ports on the US Atlantic and Gulf Coasts. These larger container ships draw deeper and squat more resulting in less underkeel clearance in entrance channels. This puts pressure on the allowable draft rules for sailing in the ports’ channels. PortMiami is no exception.

An underkeel clearance forecasting tool was developed to minimize the risk of the bottom touching in the entrance channel to PortMiami. Special attention was paid to the squat of vessels during arrival transits. Ships need to enter the channel on arrival with a speed of approximately 12 km to manoeuvre in strong and varying crosscurrents due to the Gulf Stream that are prevalent near the channel entrance. Therefore, the squat cannot be reduced by entering at a low speed. This high speed is maintained in the first section of the channel with steep dredged slopes, where bank effects cause the vessel to squat deeper in the water.

A detailed measurement campaign was conducted to better understand the squat of Post Panamax container ships and the role of the specific conditions in the PortMiami entrance channel due to the effect of currents and steep side slopes. Ship motions were surveyed during arrival channel transits on 17 Post Panamax container ships using three GPS receivers installed on the ship during each transit. The largest ship in the survey program was a 10,000 TEU ship with a width of 159 ft. Currents were measured at two locations along the channel.

The squat measurements were used to validate and calibrate numerical modeling of squat and wave response. The boundary-integral equation model was calibrated to include counter-currents and to represent increased squat at the stern due to propeller wash effects. The vessel speed in the model is the speed through water, which is the speed over ground corrected for counter currents due to tide and the Gulf Stream.

The simulated squat corresponds well to the measurements and is in most occasions close to predictions using the ICORELS squat formula. Notable exceptions are particularly for ships with non-typical length-to-width ratios, for which the numerical model performs better than the ICORELS formula. Squat is generally larger for wider ships. However, hull shape is critical. Some smaller and slender ships squat more due to a strong bow-down dynamic trim angle, while larger ships have a small stern-down trim angle.

The calibrated squat model was subsequently used to develop the underkeel clearance forecasting application. The application includes computation of all underkeel clearance components, squat, heel (due to turning and wind) and wave response. Five Post Panamax container ships are included in the application, ranging from 5,500 TEU to 14,000 TEU.

Doug Scott, Director, W. F. Baird & Associates Coastal Engineers Ltd.
Dr. Doug Scott, a Principal and Director of W.F. Baird & Associates, has specialized in the overall management and high-level technical direction of complex investigations and projects in the coastal and port engineering fields. He has successfully managed teams supporting the design of large-scale dry and liquid bulk cargo facilities from feasibility assessment through to detailed design. Key areas of expertise include metocean characterization, port layout, dredging design, identification of towage requirements, mooring design and port capacity assessment. Doug is responsible for promoting innovation within W.F. Baird & Associates with the objective of keeping the firm on the leading edge of developments within key areas of practice.

 

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