DREDGE MATERIAL MANAGEMENT PLAN, SEDIMENT PIPELINE AND STORMWATER WEIR STRUCTURE IN CAMERON PARISH
NAME OF APPLICANT: Commonwealth LNG, LLC, c/o TRC Environmental Corporation, Attn: Ms. Cindi Sedberry, One Riverway, Suite 500, Houston Texas 77056.
LOCATION OF WORK: In Cameron Parish, Louisiana; LNG Facility located at North 29.7705, West -93.3527, at 500 Gulf Beach Highway, Cameron, LA, on the Calcasieu Ship Channel near the mouth of the channel and the Gulf of Mexico. The site is situated along the west bank of the Calcasieu River, between mile markers 0 and 1. The Dredged Material Management Site (DMMS) is located on the east side of the Calcasieu Ship Channel near the south shoreline of Calcasieu Lake in the Cameron Prairie National Wildlife Refuge. The temporary dredged slurry pipeline will traverse from the berthing and turn around area northeast up the Calcasieu Ship Channel to the Cameron Loop Channel, pass under Hwy 27, then follow existing uplands to the DMMS site within the Cameron Prairie National Wildlife Refuge (NWR). Hydrologic Unit Code 08080206 Lower Calcasieu Basin.
CHARACTER OF WORK: The purpose of this addendum is to advertise changes regarding the proposed Commonwealth LNG - Dredge Material Management Plan (DMMP) for the disposal of approximately 1.73 million cubic yards of dredged material and to provide additional details for the proposed stormwater channel and weir at the proposed facility.
The May 11, 2020 Corps of Engineers public notice advertised, initially described that the applicant’s plans included offsetting project related wetland impacts with a 479.7 acre Beneficial Use of Dredged Material (BUDM) marsh creation site on the west side of the Calcasieu Shipping Channel near Oyster Lake, by using the 1.73 million cubic yards of dredged material incorporated into a marsh creation & nourishment project.
Currently, the applicant has proposed to mitigate project related unavoidable wetland impacts at approved and acceptable mitigation banks within the N.O. District, should DA permit approval be found in the public interest. Additionally, a new DMMP disposal site is proposed to accept the 1.73 million cubic yards of dredged materials and is located on the east side of the Calcasieu Shipping Channel within the Cameron Prairie NWR. An approximate 640-acre site consisting of open water and tidal marsh will be enclosed with containment berms and will receive the dredged materials which are expected to nourish the existing marsh and add sediment to the open water areas to a maximum settled target elevation of 1.0-foot at 5 years. Dredged material from the cutterhead suction dredge will be transported as a slurry in a temporary, 30-inch pipeline (slurry pipeline) to the DMMP Area. The alignment of the temporary slurry pipeline begins at the dredge within the proposed dredged area, crosses along the bottom of the Calcasieu Ship Channel (anchored as necessary to prevent disruption by flow and interference with navigation), proceeds northeast within the Cameron Loop Channel, exits the Cameron Loop Channel and passes under Highway 27, then follows existing uplands (e.g., roadbeds, levees) east and northeast, then uses temporary timber matting to be placed over previously impacted marsh, and finally turns north to the DMMP Area.
For more details see the attached public notice