In order to set the CHT system up for the At-sea mode (refer to figures 8-5 and 8-6) set soil and waste drain diverter valves H and J to the OVER-BOARD position. Open pump discharge valves B and set pump discharge diverter valve C to the overboard position. Check to insure that gag scup-per valve at the hull in the pump discharge line is open. Set the discharge pump controller selec-tor switches to the MAN1 position. After the pumps lose suction, set both controller selector switches to the AUTO position. Open the tank washdown supply valve and wash the tank for 30 minutes. Close the tank washdown supply valve. Set the controller selector switches to MAN1 posi-tion. After loss of pump suction, set controller switches in the OFF position. Close pump suc-tion valves A, discharge valves B, and, in the strainer system only, close the inflow stopvalves G.

For CHT systems outfitted will comminutors and aeration systems, secure the comminutor after setting the soil drain diverter valves. Close air blower discharge valve M and secure air blower, or close ship supply valve N after tank washdown procedures have been completed and the pump has lost suction. If an air aspirator system is in-stalled, shut the system down and secure the aspiration pump.

The CHT system is now secured with all soil and waste being discharged overboard through the gravity drainage system.

For additional information on the CHT system and its components, refer to the manufac-turers technical manuals and Naval Ships Technical Manual, Chapter 593.

NOISE POLLUTION

Hearing loss problems have been and continue to be a source of concern within the Navy, both ashore and afloat. In the Navy the loss of hear-ing can occur from exposure to impulse or blast noise (i.e., gunfire, rockets, etc.) or from con-tinuous or intermittent sounds such as jet or pro-peller aircraft, marine engines, boiler equipment operations, and any of a myriad of noise sources associated with industrial type activities (such as shipyards). Hearing loss may be temporary, and will disappear after a brief period of nonexposure, or it may become permanent through repeated exposures to intense noise levels. The loss of hear-ing sensitivity is generally in the higher frequen-cies of 4000-6000 Hertz (Hz) with many people sustaining extensive impairment before the all im-portant speech range of 500-3000 Hz is ap-preciably affected.

The Navy recognized noise pollution to be a problem and started to combat it through the Hearing Conservation Program. The main pur-pose of this program is to establish and imple-ment an effective occupational noise control and hearing conservation program which has as its goal the elimination/prevention of hearing loss.