OSHA regulations for confined space diving
We've recently found that there is a good deal of confusion in the industry about exactly what safety practices are required by OSHA when conducting diving operations in water storage tanks. To help clear things up, we checked with OSHA and the experts at Tank Industry Consultants to verify what OSHA's minimum recommended safety standards and practices are. To illustrate what we learned, let's start with a picture (apologies for the crude clipart!):
As we can see, following the minimum safety requirements means a minimum of four people will be on site: the diver in the water, a standby or rescue diver, a diver tender or observer on the tank in communication with the divers and another on the ground. The standby diver needs to be ready to assist the diver in the water, which means s/he needs to be ready to enter the water, which in the case of a potable water tank means the standby diver needs to be fully suited up and sanitized. An observer or tender is required to be at the point of entry while any diver is in the water and cannot leave that station, so another observer or helper is required to be at ground level to provide or summon assistance.
In our conversations with people around the potable water industry, it is the standby diver requirement that we've found most people to be unaware of and quite surprised to learn. This is understandable since most people doing diving work in water tanks don't follow this practice, whether they are water agency employees or commercial diving contractors. But OSHA's rules are unequivocal: persons conducting dive operations shall "station a diver at the underwater point of entry when diving is conducted in enclosed or physically confining spaces". Water storage tanks are the very definition of an enclosed space, so there is no ambiguity here! Doubling the number of divers on a job essentially doubles the cost, so it's no surprise that people are tempted to ignore this rule.
Given that water tanks are confined spaces, there are other OSHA requirements that aren't expensive to implement but are also frequently ignored. These include:
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Notifying local fire departments that work will be going on in an elevated confined space and following whatever requests they might make.
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Locating the nearest hospital with a hyperbaric decompression chamber and communicating a plan to get a diver there with all persons involved in the job.
In short, using divers for even the simplest task inside a water tank is unavoidably expensive. Following the minimum safety practices means having at least four people, two of them fully-equipped divers, on the job site at all times. Given typical labor, insurance and equipment costs in the US as of this writing in early 2018, this means that even the simplest dive operations in a water tank should cost something between $5,000 and $8,000 per day depending on location and complexity. If you are a tank owner paying divers less than this, then they are necessarily not following OSHA's minimum safety requirements, putting you in legal jeopardy, even if nothing goes wrong.
As ROV operators, we are obviously biased in favor of using robotics in place of people where possible. But it isn't just personal profit that motivates us-- one of the biggest reasons we got involved in robotics in the first place was to help people avoid risking their lives on the job unnecessarily. We enjoy SCUBA diving too, but recognize that it is never risk-free. Some tasks can only be done by divers, so it makes sense to reserve their use for those situations where they are essential. For most routine water tank inspection and cleaning tasks ROVs can do the work just as well or better than divers for a quarter the cost. Basic economics and respect for life both point in the same direction: let the robots do it!