The phrase "in a massive scale" is correct and usable in written English.
You can use it to emphasize the magnitude of something. For example, "The company expanded production in a massive scale."
So it's like hacking in on a massive scale in a given area, for example.
Ed Harrison has a good essay on how the world euro ends if the ECB doesn't step in on a massive scale.
Perhaps thinking of his disappeared cousin David, he explained: "I will believe in the Internet in Latin America on a massive scale when I believe that Latin America can produce honest politicians and an income distribution that allows teledensity rates to grow from 15% to 60%, as in Europe.
The Global Fund, the world's leading funder of programs to fight AIDS, Tuberculosis and malaria, was the first international financing body to invest in a massive scale-up of anti-retroviral treatment in developing countries.
The Iliad and the Odyssey, however, owe their preeminence not so much to their antiquity and to their place in Greek culture as a whole but to their timeless success in expressing on a massive scale so much of the triumph and the frustration of human life.
But there was no doubt at all that the News of the World had been involved in crime on a massive scale.
"I think there is no one else capable in Australia, on a massive scale, [of conducting] research across so many areas that affect so many aspects of Australians' lives".
Further, a new World Bank report shows that in addition to governments, the private sector can be a formidable partner in reaching such a massive scale.
Sandy Weill's signature accomplishment during his long career on Wall Street, Citigroup, engaged in fraud on a massive scale, unfettered risk taking and then needed a massive taxpayer bailout during the 2008 financial crisis because it was so big it couldn't be managed.
