Claims of an increase in oilsands crude flowing through the pipelines from Canada to US have forced the State Department to consider the environmental and public review before allowing the expansion, despite both pipelines having presidential permits.
The intended Line 3 expansion will see a maximum of 760 000 bpd from its present 390 000 bpd.
Line 67 is aiming to expand its capacity from 450 000 bpd to its current 800 000 bpd.
No new pipe will be laid for the project; instead pumping horsepower through each pipeline will increase the capacity.