The environmental effects that result from sewage discharges into rivers, harbors, and coastal waters by naval ships are of great concern to the Navy. The Navy is required to control sewage discharges under regulations promulgated by the Secretary of Defense. Navy policies and respon-sibilities are defined in OPNAVINST 6240.3.

The Navy plans to equip each naval ship with a marine sanitation device (MSD) which will enable a ship to comply with the sewage discharge standards without compromising the ship mission capability.

Sewage discharge regulations do not preclude overboard discharge when an emergency situation exists and when failure to discharge would en-danger the health and safety of personnel.

In the past, shipboard sewage has been discharged overboard as a matter of routine. Studies have shown that concentration of sewage in inland waters, ports, harbors, and coastal waters of the United States had detrimental ef-fects on the environment.

In 1972, anticipating the present regulations, the CNO made the policy decision to install the Sewage Collection, Holding, and Transfer (CHT) system aboard naval ships which could employ this method of sewage pollution control without serious reduction in military capabilities. The CHT system represented the least cost and risk solution to the problem.

The design goal of the CHT system is to pro-vide the capacity to hold shipboard sewage generated over a 12-hour period. This goal can usually be achieved in large ships. Smaller ships, where the maximum capacity limits holding times to 3 hours or less, which is insufficient time to transit a 3-mile restricted zone, cannot achieve such a goal.