Unit
IV Case Study
Consider
the scenario below:
Workers need to enter a below-ground, concrete-lined vault to
repair a leaking valve that controls the flow of wastewater from several buildings
at your plant. The opening for the pit is outdoors and secured with a 36-inch
diameter manhole cover. The pit is 12 feet deep, and the walls are 6 feet x 6
feet wide. The valve is at the bottom of the vault. You opened the cover,
tested the atmosphere, and found oxygen levels to be at 16%. No toxic
substances were detected. After ventilating the space for 15 minutes, the
oxygen reading reached 18% and remained at that level.
Address
the following items:
Using the flow chart in Appendix A of 29 CFR 1910.146, determine
the classification of the space. Explain how you reached the decision.