"King Solomon conscripted laborers from all Israel - thirty thousand men. He sent them off to Lebanon in shifts of ten thousand a month, so that they spent one month in Lebanon and two months at home. Adoniram was in charge of the forced labor." NIV translation
Solomon made foreigners living in Israel slaves and sent them to Israel to help with the cedar trees. King David had used forced labor but Solomon expanded it tremendously for his building projects.
"Solomon had seventy thousand carriers and eighty thousand stone cutters in the hills, as well as thirty-three hundred foremen who supervised the project and directed the workers. At the king's command they removed from the quarry large blocks of high-grade stone to provide a foundation of dressed stone for the temple." NIV translation
This was a massive construction project as we see by the large number of workers. They did not have modern machines so they required many men to do the work. Most of the work was done off site as the stones were cut and dressed at the quarry.
"The craftsmen of Solomon and Hiram and workers from Byblos cut and prepared the timber and stone for the building of the temple." NIV translation
Byblos was a city on the coast of Lebanon and the workers that are referred to would have been the men that made the logs into floating rafts and delivered them to Israel.