Roxbury CO's 1,2,and 3 were dispatched for a fire at the old Kenvil Concrete plant. Chief Alberti arrived on scene to find a vacant 2 1/2 story well involved. I/C advised this would be a exterior attack only and called for a tanker task force. While the task force was e/r the roof over the main portion of the bldg collapsed. I/C initially requested Netcong F.A.S.T. and Jefferson Co#2 tanker. Jefferson tanker was put to work on the C/D site with 4 lines and was the dump site pumper. Tanker task force included Mt. Arlington, Chester, Budd Lake, Rockaway Twp, and Mendham Twp. Wharton secured a draft site for the tankers. Randolph secured a hydrant and worked with Roxbury to lay almost a mile of LDH for water supply. Once the fire was k/d a excavator was called in to open up the rest of the bldg while the MCPO Arson Squad and MCSO CIS investigated.