§ 33.315. Excavations, 4 to 10 feet in depth and more than 42 inches in width.

 (a)  In hard, solid soil, timber shall be used as follows:

   (1)  Uprights. Two by 6 inch planks spaced approximately 6 feet apart center line to center line.

   (2)  Stringers. Four by 6 inch planks spaced vertically 4 feet apart center line to center line.

   (3)  Cross braces. Four by 6 inch planks spaced horizontally 6 feet apart center line to center line.

 (b)  In soil likely to crack, timber shall be used as follows:

   (1)  Uprights. Two by 6 inch planks spaced 3 feet apart center line to center line.

   (2)  Stringers. Four by 6 inch planks spaced vertically 4 feet apart center line to center line.

   (3)  Cross braces. Four by 6 inch planks spaced horizontally 6 feet apart center line to center line.

 (c)  In soft, sandy soil or filled ground, timber shall be used as follows:

   (1)  Uprights. Two inch close sheeting.

   (2)  Stringer. For depths less than 7 feet, two 4 by 6 inch planks, and for depths of 7 to 10 feet, three 4 by 6 inch planks.

   (3)  Cross braces. Four by 6 inch planks spaced horizontally 6 feet apart center line to center line.

   This section cited in 34 Pa. Code §  33.319 (relating to tables).