SUMMARY

discharge under regulations issued by the Secretary of Defense. In the past, shipboard sewage has been discharged overboard as a matter of routine design and operation. Studies have shown that concentrations of sewage in inland waters, ports, harbors, and coastal waters of the United States is detrimental to the environment. The Navy has installed marine sanitation devices (MSDs) on ships. The MSDs allow ships to comply with the sewage discharge standards without compromising mission capability. In 1972, the Chief of Naval Operations (CNO) made the policy decision to install the sewage collection, holding, and transfer (CHT) system aboard naval ships. The CHT system is designed to hold all shipboard sewage that is generated over a 12-hour period. On large ships, this goal can usually be achieved. For smaller ships, the maximum capacity would limit holding time to 3 hours or less, an insufficient time for the ship to transit the 3-mile restricted zone. The Jered sewage treatment plant and the LHA sewage treatment plant are other types of MSD systems. The Jered sewage treatment plant is designed for a zero liquid discharge. It is capable of using the vacuum-burn principle. Sewage is first collected by a vacuum and then disposed of by incineration. Sewage can be discharged overboard when the ship is at sea or pumped to shore via a connection facility. The LHA sewage treatment plant is a biological sewage treatment process in which sewage and activated sludge can be mixed and aerated. The activated sludge is separated from the treated sewage by sedimentation and discharged or returned to the process as needed. There are distinct hazards to personnel associated with all sewage systems. These hazards include explosive gases, toxic vapors, and biological contaminants. When operating a CHT system, for example, personnel must be extremely careful so spills do not occur. ALL SPILLS CAN BE EXTREMELY HAZARDOUS TO PERSONNEL. In addition to the removal of CHT contaminants, CHT spills are sanitized with disinfectants so that residual bacteria are eliminated. Medical department personnel must be notified of any CHT black water spills. Medical department personnel must also supervise cleanup and sanitation operations in spill areas. For further information on sanitation systems, refer to Hull Maintenance Technician 3 & 2, volume I, NAVEDTRA 10571 (series), chapter 15, and NSTM, chapter 593. SUMMARY This chapter introduced you to environmental hazards and control. Remember, pollution takes many shapes and forms. Pollution attacks the environment and directly or indirectly affects each of us. Consequently, we must protect the environment by preventing pollution. On board ship, certain forms of pollution are sometimes difficult to control, such as heat and noise. In these cases, the first line of defense is PROTECTION. In all other cases, we must be concerned with PREVENTION. Keep in mind that prevention of pollution, in any form, is everybody’s business. Pollute your environment, and your environment will pollute you. 13-7