If you do not trawl a site, you can verify that the site is clear of obstructions by using any of the methods shown in the following table: ----------------------------------------------------------------------------------------------------------------
(a) Sonar, cover 100 percent of the appropriate Use a sonar signal with a
grid area listed in Sec. 250.1741(a), frequency of at least 500
kHz.(b) A diver, ensure that the diver visually inspects Ensure that the diver uses
100 percent of the appropriate grid a search pattern of
area listed in Sec. 250.1741(a), concentric circles or
parallel lines spaced no
more than 10 feet apart.(c) An ROV (remotely operated vehicle), ensure that the ROV camera records Ensure that the ROV uses a
videotape over 100 percent of the pattern of concentric
appropriate grid area listed in Sec. circles or parallel lines
250.1741(a), spaced no more than 10
feet apart.----------------------------------------------------------------------------------------------------------------