A method of, and system for, collecting and controlling hydrocarbons leaking from offshore sea bottom environments entail providing a concrete containment barrier and catenary gasket around the leak source, pumping concrete onto the catenary gasket, opening ports and valves in a containment vessel while it is positioned over the leak source, at least partially embedding the containment vessel in the pumped concrete, closing the ports and valves to capture leaking fluids, and communicating the fluids to the surface for further processing. The modular containment barrier may be placed around an existing or potential well site, or an operating well, abandoned well or sea bottom fissure to facilitate implementation of the method in the event of a leak.