Corpus Christi: Disposal Zones and Mound Control

More room for placement

The expanded offshore disposal sites at Corpus Christi took effect on 28 October. EPA's September final rule increases the Ship Channel site's area from 0.61 to 1.05 square nautical miles and the New Work site's area from 1.39 to 5.57 square nautical miles. The accompanying management plan connects disposal positions to the height and spread of the resulting seabed deposits. [1, 2] EPA extended the Ship Channel site southwest and the New Work site in four directions. The sites lie roughly 1.7 and 2.7 nautical miles offshore, respectively. The rule responds to long-term demand for suitable dredged material disposal in the Corpus Christi Bay area. Each project's material suitability and disposal authorisation remain subject to the Corps' and EPA's review. [1] For a dredging estimate, the larger footprint creates a placement choice. The selected release position determines the loaded voyage and the return leg; spreading loads changes the local build-up. A production programme needs both the sailing cycle and a placement sequence based on recent bathymetry.

Keep the release inside the working zone

The September Site Management and Monitoring Plan applies a release zone at least 100 metres inside the site boundary. It recommends starting and completing discharge, with doors closed, inside that zone through the project authorisation. Appendix B supplies case-specific permit language. The underlying regulation defines an envelope extending 100 metres from the vessel perimeter throughout dumping. Vessel width and movement therefore enter the release geometry. [2, 4] Plot the authorised release zone separately from the outer site boundary in the vessel's operating system. Check the planned discharge track against vessel movement and the time needed to finish discharge. A voyage ending at the nearest outer boundary leaves those manoeuvres outside the estimate. The plan's action table identifies mound heights above the existing bed of more than 10 feet at the Ship Channel site and 15 feet at New Work, with alternative heights available by EPA-Corps agreement case by case. Responses include changes to disposal methods and restrictions on volume. It recommends a post-disposal bathymetric survey within 45 days of project completion. [2]