Carderock Division Naval Surface Warfare Center, Ship Systems Engineering Station, Bldg. 77L, Philadelphia, PA 19112-5083

46 -- SEWAGE HOLDING TANK FOR AMPHIBIOUS SHIP CLASSES POC R. Schepis, 215-897-7449. The U.S. Navy is currently designing a new sewage tank for one of its amphibious ship classes. This tank will be unusually large for a Navy Ship, about 135,000 gallons capacity. Sewage waste collected in it will require continous aeration. Because of the tank's large size, the Navy's standard aeration systems cannot meet air flow demands. We realize other aeration systems and technologies are available that may be acceptable for Navy use. The Naval Surface Warfare Center, Carderock Division, Philadelphia ia therefore searching the commercial market for a system that can satisfy this requirement. The system is not intended to provide sewage treatment, but simply to maintain an aerobic environment and keep solids from settling. The tank will be approximately 48 feet long, 16 feet wide and 24 feet deep and will vent to the atmosphere. It will have a pair of 300 GPM sewage discharge pumps activated by float-type level sensors. A sensor at 15 percent tank capacity (about 20,000 gallons, 3.6 feet from the tank bottom) activates a single pump (the ''duty'' pump). Another sensor further up activates the other pump (''standby'' pump) if the sewage level should rise that high. A sensor at 7 percent (about 9,500 gallons, 1.7 feet from the bottom) deactivates both pumps. The system operates between the 7- and 15-percent levels about 95 percent of the time, while the ship is in port. When the ship is underway in restricted water, it must collect and hold its sewage. The discharge pumps are manually shut off and the tank is allowed to fill to capacity. This operational mode occurs about 5 percent of the time. The aeration system must operate at all tank levels from the pump deactivation sensor to completely full. Tank access is difficult, so the system should be a simple mechanical type that is highly reliable and easy to maintain. The tank dimensions given are only approximate in order to make an order-of-magnitude assessment of the problem. If your company designs or manufactures equipment that could possibly aerate this tank, please send product information to: Naval Surface Warfare Center, Carderock Division, Philadelphia, U. S. Naval Base, Bldg. 619, Philadelphia, PA 19112-5083, Attn: Code 631; R. Schepis. This synopsis is for information purposes only, does not constitute a solicitation, and should not be construed as a commitment by the Government. This synopsis does not obligate the Navy to purchase any literature or products. (0060)

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