Abstract: A working chamber is placed in a lined pond containing a body of contaminated water and filled with clean water to safely isolate divers while they repair damaged areas of the liner. The chamber is an open ended housing having a side wall of water impervious material configured to surround the area of liner damage and a height greater than the depth of the body of water at the repair site. Buoyancy tanks float the housing in a stable upright position above the repair site and are filled with clean water to sink the housing to rest its bottom end on the liner at the bottom of the body of water. A deformable seal on the bottom end of the housing engages the liner surface surrounding the area of liner damage and is filled with water to forming a substantial water sealing relation therewith but with controlled leakage. Clean water is conducted into the chamber interior at a predetermined rate to displace contaminated water inside the chamber.

Abstract: A safety valve and system is disclosed for hydrocarbon storage tanks having a floating roof construction and provision for drainage of water from the floating roof. The floating roof is constructed to collect water on top and discharge the same through a drain connected to a flexible drain line leading to an outlet opening. If the flexible line should break or otherwise become open to the contents of the tank, there is danger of leakage of the contents from the tank with attendant environmental danger and danger of fire. This invention comprises a valve which responds automatically to the presence or absence of water in the drainage line and is closed in the absence of water or the presence of hydrocarbons in the valve. The valve is motor operated electrically by storage batteries which are recharged by a solar panel. When the valve is empty of water or filled with hydrocarbons, sensors cause the valve to close.