For optimal safety (so cars cannot pass through) the distance between 2 bollards will be 4ft. (1219mm). In a case were 6 bollards will be placed a trench needs to be dug with the dimensions: 8750 x 1000mm with a depth of 1500mm. At the bottom of this trench (drainage) gravel with size 25-30mm needs to be placed that will function as a drain for (underground) water. This layer will have a height of 300mm. The foundation boxes of the bollards can then be placed above the drainage gravel (foundation boxes need to level)