29 C.F.R. § 1926.802 – Cofferdams.

(a) If overtopping of the cofferdam by high waters is possible, means shall be provided for controlled flooding of the work area.
(b) Warning signals for evacuation of employees in case of emergency shall be developed and posted.
(c) Cofferdam walkways, bridges, or ramps with at least two means of rapid exit shall be provided with guardrails as specified in subpart M of this part.
(d) Cofferdams located close to navigable shipping channels shall be protected from vessels in transit, where possible.