‹‹‹ Vitr. 5.12.4 | Table of Contents | Vitr. 5.12.6 ›››
5When the place does not afford the powder named, the following method is to be adopted. Double dams are constructed, well connected with planks and chain pieces, and the cavity between them is filled up with clay and marsh weeds well rammed down. When rammed down and squeezed as close as possible, the water is emptied out with screw pumps or water wheels, and the place is emptied and dried, and the foundations excavated. If the bottom be of loose texture, it must be dug out till a solid bottom is come to, wider than the wall about to be erected, and the wall is then built of stone, lime, and sand.
5But in places where this powder is not found, the following method must be employed. A cofferdam with double sides, composed of charred stakes fastened together with ties, should be constructed in the appointed place, and clay in wicker baskets made of swamp rushes should be packed in among the props. After this has been well packed down and filled in as closely as possible, set up your water-screws, wheels, and drums, and let the space now bounded by the enclosure be emptied and dried. Then, dig out the bottom within the enclosure. If it proves to be of earth, it must be cleared out and dried till you come to solid bottom and for a space wider than the wall which is to be built upon it, and then filled in with masonry consisting of rubble, lime, and sand.