Section 3.10: Site Plans and Technical Data - Rick Neufeld Comments

Northern Gateway Pipelines Inc.
Section 3.10: Site Plans and Technical Data
Table of Contents
The following provides a summary of the results of the wind analysis:
• The maximum measured sustained winds, converted to a 10 metres reference height, were from the
northeast with a speed of 20.3 metres/s (73 km/hour) (39.4 knots);
• The maximum measured sustained winds, converted to a 10 metres reference height, from the
southwest were 18.4 metres/s (66 km/hour) (35.8 knots); and,
• The project site is relatively exposed to winds along the Douglas Channel and will likely be most
affected by the predominant winds from the northeast and southwest, i.e. aligned with the main axis
of the channel.
These wind data formed the basis of a computer-based mooring analysis that was carried out as part of the
preliminary design work. Additional mooring analyses will be carried out as part of the design process.
3.2 Wave Data
Both recorded wave data and estimated wave data, derived from the recorded wind data, were utilized in
the wind and wave analysis (Reference 6). Like the wind data, the wave data was obtained from the
Nanakwa Shoal Marine Buoy station. Although the recorded wave data is generally representative of the
overall wave climate in Douglas Channel, it is specific to the Nanakwa Shoal area and may not be entirely
representative of the wave conditions at the project site. The wave conditions at the project site can be
estimated from the wind data using hindcasting methods and fetch conditions specific to the project site.
Although the recorded wave data and estimated wave data represent different locals in Douglas Channel,
they can be roughly compared for validation purposes.
3.2.1 Recorded Wave Data at Nanakwa Shoal
The recorded wave data from the Nanakwa Shoal Marine Buoy dataset provides a general understanding
of the wave climate in Douglas Channel and can be used for general verification of the wave conditions at
the project site. However, a review of the raw wave data indicated several irregularities in the dataset,
causing concern about its validity. After removing apparent outliers in the wave height sequence, the
maximum overall wave height for locally generated waves was determined to be approximately 1.5
metres. For waves specifically coming from the south to southwest, the maximum wave height was
determined to be approximately 1.1 metres.
A statistical analysis was performed on the Nanakwa Shoal wave data to determine the extreme wave
heights for various return periods using the ACES Code of Extremal Analysis (Reference 6). Any waves
with a period of 5 seconds or greater were deemed erroneous and were filtered out of the analysis. The
program used Weibull distributions to determine the significant wave heights at Nanakwa Shoal for the
return periods of 2, 5, 10, 25, 50 and 100 years. The results of the analysis are summarized in Table 3-2.
The significant wave height, HS, is the average of the highest one-third of all waves.
Page 3-4 FINAL - Rev. 0 January 20, 2010