Trans Mountain Pipeline (ULC)

Trans Mountain Expansion Project

Volume 8A

Volume 8A – Marine Transportation

Page 8A–68

The design capacity of the dock includes an allowance for spot capacity, the use of which will

vary with market conditions. If the spot capacity is not used the number of vessels will be lower.

Through an “open season” process shippers have contracted with Trans Mountain for the

majority of the 141,500 m

3

/d (890,000 bbl/d) capacity of the expanded system and have

indicated Westridge Marine Terminal as the preferred destination for up to 93,500 m

3

/d

(588,000 bbl/d). In addition to this firm capacity the Project includes an allowance for up to

6,700 m

3

/d (42,000 bbl/d) of spot capacity for a total of up to 100,200 m

3

/d (630,000 bbl/d). The

actual deliveries of firm and spot volumes will be driven by market conditions and shippers will

have the ability to redirect contracted volumes from Westridge to Puget Sound.

The number of vessels required to lift the delivered capacity depends on vessel size. Trans

Mountain does not nominate, own, or operate the tankers that call Westridge Marine Terminal.

Trans Mountain believes that the large majority of tankers nominated by shippers will be of the

Aframax class, the largest size currently allowed by PMV, as these vessels will allow shippers

the greatest economies of scale. The estimate of 34 tanker loadings per month is based on an

all Aframax class case. However, the number could also be influenced by the substitution, by

shippers, of some Panamax class tankers, which have less capacity than Aframax class

tankers. If substitution occurs, there may be a slight increase in the number of loadings. Trans

Mountain has calculated that a 25 per cent Panamax class substitution could add two or three

loadings per month. These vessels and their characteristics are described in TERMPOL 3.9 in

Volume 8C (TR 8C-7).

As described in Section 2.1.4, due to Second Narrows MRA restrictions, the extent of loading is

determined by tidal height and varies with the tidal cycle. The number of vessels required will

increase during periods of lower high tides and decrease during periods of higher high tides.

Similarly draft is also affected by product density, which varies between petroleum types. There

is also a general trend within the tanker industry to higher capacity tankers (within each class)

and tankers carrying “light” synthetic crude oil will be able to load more cargo on a volumetric

basis than those carrying “heavy” crude oil.

The maximum cargo loadable on a tanker is, therefore, subject to a combination of many

factors, including the individual tanker’s dimensions (

i.e.,

cargo capacity, draft, and breadth), the

cargo density, and tidal cycle. While substitutions by Panamax class tankers would have the

tendency to slightly increase the number of loadings, that tendency would be offset by

fluctuations in demand and greater cargo volumes per tanker as a result of the combination of

factors discussed. As a result of these factors, Trans Mountain believes that 34 Aframax tanker

loadings per month is a reasonable estimate for purpose of assessing Project-related effects

(Table 2.2.1).