Continue laying smaller and smaller diameter circles of mound clay on top of each other until the mound has reached the height marked on your stake in the center of the circle. The biggest problems with pitching mounds is the maintenance of the mound. Rock carvings from mysterious prehistoric civilization Repeat moistening, adding powdered clay, raking it in, until the level is almost back to normal. How to build a pitcher's mound with clay bricks . The dimensions of the mound are 84 x 42. 300 bricks = 36 (50 lb.) bags by weight but only 25 bags by volume. From rebuilding a pitching mound to building a sports complex, we provide professional quality at affordable prices to all of our customers. It not only looks great but allows for enough water absorption for longevity and durability. Higher clay content allows for greater compaction. Totally agree with 'foreplease', a well built mound is usually built with clay bricks. Become firm clay when watered...