Crews from the U.S. Army Corps of Engineers Little Rock District set two cofferboxes around the center-post receivers in the David D. Terry Lock Chamber near Scott Arkansas on Aug. 19. David D. Terry Lock and Dam is one of 13 structures on the McClellan-Kerr Arkansas River Arkansas River Navigation System in Arkansas that allows the shipping industry to move commerce up and down the system.Something that can’t be seen in the video is the tremendous work being done underwater by the Little Rock District Dive Team. Without their hard work this operation could not have taken place.Ensuring center-post receivers can be set and secured is a critical part of a lock dewatering. The lock chamber is 110 feet wide. The center-post allows 50 foot stop-logs to be placed on both sides.The cofferboxes allow maintenance crews to pump out the water, inspect the receivers and perform a pull test to ensure they still function as intended. The boxes were designed after crews found other center-post receivers along the system to be inoperable. Depending on the configuration, the locks with inoperable center-post receivers have to be retrofitted to use costly 110 foot stop-logs or have the center-post anchor bolts replaced.If the existing center-post receivers pass the pull test they won’t require costly modifications.