When I was on an amphibious assault ship we pulled into Earle several times (post 9/11) to onload and offload weapons...everything from bombs and missiles for the Harriers to the RAM and Sea Sparrow missiles for the ship's anti-missile defense, and small arms ammo. Usually after a cruise the ships go into the shipyards for overhaul and you don't want any ordnance/munitions onboard when doing hot work. So after cruise offload, and before workups onload.
The tank cars were used to receive the sewage from the ships CHT tanks. In the old days they pumped it over the side but not anymore.
Most cruisers and destroyers out of Norfolk go to Yorktown Naval Weapons Station to get ordnance.
I found this article about Charleston Naval weapons station:
Irby acted as tour guide for the Richmond LOA members. “We have 80-95 ship visits a year,” Irby told the group. “We service all ships other than carriers and large amphibians. Carriers are supplied at sea, and larger ships are done at Naval Weapons Station Earle, Colt’s Neck, N.J.”
http://www.willdaniel.com/clips/092806_loa_yorktown.htm
There are three East coast Naval Weapons stations:
Earle NJ (Amphibious assault groups)
Charleston SC (?...)
Yorktown VA (Destroyers, Cruisers)
There's also Sunny Point Military Ocean Terminal North Carolina that stores ammunition for the Army, it also has piers and a railroad.
I think we are going to see Earle become very busy over the next year or two as combat operations in Iraq are drawn down and all that equipment down range starts coming back to the States, the military population of Earle has actually shrunk quite a bit in the last 5-10 years as most of the homeported ships have been transfered from the Navy to the Civilian Military sea lift command. Which is why Earle is looking to sell off part of their housing to civilians, they don't have the thousands of sailors from the ships based there anymore. Most of Earle's missions is to supply ships on their way to or coming back from deployment who only stop for a couple days at the most.
There are discussions about adding Earle as a storage location for the Army/National Guard and connecting the weapons depot with Lakehurst/Fort Dix via a new rail head at Lakehurst, Earle would make a great point of departure for the 10th Mountain division and their equipment from Fort Drum. Fort Drum used to use the former Military Ocean terminal in Bayonne but now I believe they use Howland Hook on Staten Island, they should use Earle as they can pull their equipment trains all the way out to the ships on the pier.