April 26 (Reuters) - The Canada Energy Regulator (CER)

has six leave-to-open applications left to consider for the

590,000 barrel-per-day Trans Mountain pipeline expansion

project, a CER spokesperson said on Friday.

The Canadian government-owned pipeline expansion will nearly

triple the flow of crude from Alberta to Canada's Pacific Coast

and open up access to Asia and the U.S. West Coast. So-called

leave-to-open orders signal permission from the regulator that a

section of pipeline can start operating.

After years of construction delays and cost over-runs,

oil market participants are watching closely for when the

expansion opens.

Earlier this month Trans Mountain said the pipeline

would begin transporting oil on May 1.

The company did not immediately respond to a request for

comment on whether all six outstanding leave-to-open

applications need to be approved before operations can start.

The CER has so far approved 36 out of 42 leave-to-open

applications received from Trans Mountain, covering pipeline

spreads, pump stations and tanker loading facilities.

According to the CER website each section of the pipeline

requires leave to open before it can begin operating.

The CER has typically been approving leave-to-open

applications within a week or two of them being submitted by

Trans Mountain.