The phrase "a mammoth task to" is correct and usable in written English.
It can be used to describe a very large or difficult task that requires significant effort or resources to complete.
Example: "Completing the project on time proved to be a mammoth task to manage, given the limited resources available."
Alternatives: "a monumental challenge to" or "an enormous undertaking to".
Back in April 2011, we embarked on a mammoth task; to build a 24 hour literary clock.
It is a mammoth task to reach every village in this vast land of some of the most inaccessible deserts and highest mountains in the world.
A real zero-roaming Europe hinges on a major telecom market reform, which is a mammoth task to achieve in just 13 months".
It will be a mammoth task to find somewhere more affordable than the evidently not-so-affordable property we currently live in.
Relief workers "have a mammoth task to alleviate the sufferings of this vast number of Iraqis," a draft report on the Red Crescent figures says.
"We knew it was a mammoth task to stay up.
In the meantime, the authorities face a mammoth task in trying to shut down illegal waste exports, including e-waste which is sent to the developing world where components are melted down in often primitive conditions.
Some advocates of cleaning up the nation's nuclear legacy, a mammoth task that is expected to take decades and cost up to $260 billion to complete, said they feared that problems at such a prominent stimulus project could make it more difficult to get financing in the future.
The Human Cell Atlas will map out the internal workings of every cell type in the body, a mammoth task that is bound to open up new avenues in medicine.
Gandhi, the station manager, said cleaning the platforms, concourse and crowded approaches had been a mammoth task but that he hoped to continue the effort.
In many poor countries, distributing the drugs, teaching people to take them and monitoring levels of virus, T-cells and drug residues in the blood amount to a mammoth task.
