Note: | Silage pits are exempt from this section. |
Reference: | For requirements relating to confined spaces, see WAC 296-307-642 through 296-307-656. |
SOIL OR ROCK TYPE MAXIMUM ALLOWABLE | SLOPES (H:V) (1) FOR EXCAVATIONS LESS THAN 20 FEET DEEP (2) |
STABLE ROCK | VERTICAL (90°) |
TYPE A | 3/4:1 (53°) |
TYPE B | 1:1 (45°) |
TYPE C | 1 1/2:1 (34°) |
1 Numbers in parentheses next to maximum allowable slopes are angles in degrees from the horizontal. Angles have been rounded off.
2 Sloping or benching for excavations greater than 20 feet deep must be designed by a registered professional engineer.
Competent person. Someone who is able to identify working conditions that are hazardous to employees, and has authority to take prompt action to eliminate the hazards.
Wash. Admin. Code § 296-307-061
Statutory Authority: RCW 49.17.010, 49.17.040, 49.17.050, 49.17.060. 05-01-166, § 296-307-061, filed 12/21/04, effective 4/2/05. 97-09-013, recodified as § 296-307-061, filed 4/7/97, effective 4/7/97. Statutory Authority: RCW 49.17.040, [49.17.]050 and [49.17.]060. 96-22-048, § 296-306A-061, filed 10/31/96, effective 12/1/96.