250.1742—What other methods can I use to verify that a site is clear?
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:
| If you use— | You must— | And you must— |
|---|---|---|
| (a) Sonar | cover 100 percent of the appropriate grid area listed in § 250.1741(a) | Use a sonar signal with a frequency of at least 500 kHz. |
| (b) A diver | ensure that the diver visually inspects 100 percent of the appropriate grid area listed in § 250.1741(a) | Ensure that the diver uses a search pattern of concentric circles or parallel lines spaced no more than 10 feet apart. |
| (c) An ROV (remotely operated vehicle) | ensure that the ROV camera records videotape over 100 percent of the appropriate grid area listed in § 250.1741(a) | Ensure that the ROV uses a pattern of concentric circles or parallel lines spaced no more than 10 feet apart. |