EE was helping to prepare the work site to begin daily grout work. The crew had to pull tow 500' joints of polyline three crosscut, appx. 525'. EE stated he felt a pull in his lower back while pulling the first joint. There were 5 men spread out on the poly line, EE being the third in line. The size of the poly line was 1 1/4"". EE did not report this accident till 3/14/2014