Board of Water Supply. City Water Tunnel No. 2. Patrick McGovern, Inc., contractor. View in tunnel showing north end of the 17 foot diameter sidewall forms in position for concreting. Concrete cars are brought up an incline at the far end to the upper level, then dumped on either side on the top platform. Concrete is then deposited behind the forms by hand labor. The compressed air hoist shown on the platform is used for drawing the train of cars up the incline and then for moving the forms into position for the next pour. July 21, 1931.