Gunpowder, high explosives, solid rocket fuels and propellants and pyrotechnics, besides being classified under the general heading of explosives, all have in common the characteristic of deterioration with age. When this deterioration occurs, these articles become unstable; that is, they become easily susceptible to ignition or explosion. Within the Navy, safely disposing of over-age, obsolete, damaged or otherwise deteriorated explosives has been a slow, expensive, and, more often than not, a hazardous process. Two principal methods of disposal have been employed. The first method is by burning the explosive after it has been removed from a cartridge case or con- when salvage of the brass or metal parts is an objective of the disposal operation. This method is not especially satisfactory. Not all explosives can be burned, and special apparatus is required to ream or steam the explosive from the metal parts. It is slow, and it is a low- volume disposal system. Furthermore, the drilling, steaming, and burning of explosives obviously is potentially dangerous and, notwithstanding the fact that part of the cost is offset by the value of the metal parts salvaged, it is expensive. The second method of disposing of deteriorated explosives is by deep water dump.
Operation CHASE is a unique method of deep water dump.
The deep water dump has been for many years, and is today, the preferred method for disposing of deteriorated explosives, primarily because it is a large volume operation. Preferred or not, deep water dump has been an expensive and hazardous method. The expense and the hazard stem from the multiple handling of the material, both ashore in preparing the material for dumping and at sea during actual dumping operations. Until the advent of Operation CHASE in May 1964, the accepted procedure, if the ordnance did not in itself have a negative buoyancy, was to load the explosives into containers to achieve a negative buoyancy of 100 pounds per cubic foot. This procedure sometimes required the addition of sand or cement to each container for additional ballast. These containers were then loaded in a ship, transported to the dump site, and manhandled over the side. Drop-bottom barges were sometimes used so that the explosives would not be handled again at sea. This was somewhat unsatisfactory because barges had only a limited capacity as compared to a ship, and oftentimes the cargo would hang up in the bottom hatches and would have to be brought back with the barge.
In 1964, it was estimated that it cost $78.00 per ton to dispose of explosives by this method. This cost included charges for preparing the material to ensure negative buoyancy, handling and loading in port, and dumping at sea. As will be shown later, these costs were dramatically reduced when the Operation CHASE technique was employed.
In late 1963, just prior to the commencement of the Southeast Asia build-up, the Bureau of Naval Weapons (now the Naval Ordnance Systems Command) began receiving numerous queries from higher authority as to the condition of the expendable ordnance held in the Naval Ammunition Depots (NADs). Much of this ordnance had been in storage since the Korean conflict and, in some cases, since World War II. BuWeps, at this time, undertook a large surveillance program to determine to what degree, if any, this ordnance had deteriorated during its long storage. Much of it had been stored deep in magazines at ammunition depots and was found to be in excellent condition.
Unhappily, not all the ordnance was so stored, and soon there was an increase in requests for shipments of deteriorated explosives to the deep water dump preparation sites. In addition, the closing of the NAD at Hastings, Nebraska, had generated large quantities of explosives that were awaiting disposal. Most of the excesses were shipped by rail from Hastings to load-out ports in USNX cars (government-owned railway cars especially designed for transporting explosives) and, as capacity to store the excesses at coastal activities was reached, the Navy was forced to stow these explosives in the open or in the USNX cars. The rapid build-up of material awaiting deep water dump on both East and West Coasts soon indicated that a faster, cheaper, large volume method of disposal must be found.
As CHASE was conceived, the Navy, through Military Sea Transportation Service (MSTS), obtains obsolete, surplus, World War II cargo ships from the U. S. Maritime Administration. These ships are transferred to the Navy at no cost since they have no value beyond their intrinsic worth as scrap metal, and there is little demand for them as scrap. The hulk is towed to the out-loading port and there stripped of any usable machinery or equipment. The ship is then filled with the explosives to be disposed of, the cargo being stowed as any general cargo would be stowed. No special preparation of the explosives is required before lading. Hence, they are generally hoisted into the ship on the same pallets or in the same containers in which they were stored. When the ship is loaded, the cargo hatches are closed, and the hulk, escorted by a Coast Guard cutter, is towed by a commercial or Navy tug to the deep water dump site. The deep water dump site is “at least ten miles from any shoreline and in water of at least 1,000 fathoms depth,” to quote the Chief of Naval Operations instruction on deep water dump. After arrival at the site, an Explosive Ordnance Demolition (EOD) team opens the sea cocks on the hulk. It takes about three hours for the average ship to fill and sink. The C-3 Liberty hull will take about 8,000 tons of cargo to the bottom.
The inspiration for Operation CHASE came from the U. S. Army, which, in 1958, was faced with the ticklish problem of disposing of 8,000 tons of mustard and lewisite chemical warfare gas. The Army solved its problem by loading the gas into the SS Wm. Ralston, towing her to sea and scuttling her. The method was not used again, however, until the Navy’s Operation CHASE commenced.
The first CHASE ship was the SS John F. Shafroth, which was taken out of the National Defense Reserve Fleet at Suisun Bay, California, and towed to Naval Weapons Station Concord, California, for stripping and loading. The Shafroth cargo was predominantly 40- mm. ammunition from NAD Hastings, but it also included a mixed bag of bombs, torpedo warheads, mines, cartridges, projectiles, fuses, detonators, and boosters, including some over-age Polaris motors which weighed up to 33,000 pounds each.
Most subsequent CHASE ships have also loaded this type of mixed cargo. CHASE ships included material from the other services; recently the Canadians have requested space on future disposals. The Shafroth’s cargo even included a quantity of contaminated cake mix which an Army court had ordered dumped at sea. The Shafroth departed NWS Concord under tow, late on 22 July 1964, and reached the deep water dump site 47 miles west of the Golden Gate early the next morning. The sea cocks were opened by the EOD team at 1135. At 1403, the SS Shafroth disappeared beneath the surface without incident, carrying 9,799 tons of cargo. When the figures were in, it was determined that the operation had been carried off at a cost of about $22.00 a ton— a saving of $56.00 a ton over the old method.
As comforting as that statistic was to the promoters of CHASE, it was soon evident that each CHASE out-loading was unique and would present its own different set of problems. The second CHASE ship was the SS Village which was loaded at NAD Earle, New Jersey. The Village was towed to the deep water dump site on 17 September 1964, loaded with 7,348 short tons of cargo. She sank bow first at a 45-degree angle three hours and 32 minutes after the EOD team had opened the sea cocks. Five minutes after she sank, three large explosions were heard and felt. An oil slick and some debris appeared on the surface. It was obvious that some part of the cargo had detonated either as a result of water pressure or impact when the hulk hit the ocean floor.
The explosion was sufficiently large to register on seismic equipment all over the world. Inquiries were soon being received in this country regarding the seismic activity off the east coast of the United States. The explosion also aroused the interests of the Office of Naval Research (ONR) and the Advance Research Projects Agency (ARPA), as well as other groups in the scientific community. ONR and ARPA were fundamentally interested in measuring seismic travel times and attenuations of seismic signals with distance. Such explosions, at a known site and at a known time, provide a precise source for these determinations, which previously had been made from earthquakes whose location and time had to be adduced from the same signals from which the travel times and attenuations were being determined. ONR and ARPA were also interested in determining whether or not a distinction could be made between manmade underwater shocks and natural seismic shocks. Being able to make such a distinction would be invaluable in monitoring of possible underwater nuclear explosions which are banned under the provisions of the nuclear test ban treaty.
ONR and ARPA proposed, and the Navy agreed, that the next CHASE ship would be instrumented and rigged to detonate at a prescribed depth and at a controlled location.
The third CHASE ship was the SS Coastal Mariner. She was not scheduled for scuttling until July 1965 because of extraordinary preparations and precautions that would be required by virtue of the fact that her cargo was to be detonated.
The tasks to be completed in preparing the Coastal Mariner for her trip to the bottom were many and complex. Besides instrumenting the ship, selecting her cargo, and devising the means of exploding the cargo at a predetermined depth, there was the enormous task of co-ordinating the mission with all other interested parties. The scientific community throughout the world had to be alerted as to when and where the explosion would take place. The Coast Guard had to issue a Notice to Mariners advising that the area would be restricted on the day of the sinking. Air surveillance had to be provided in order to warn off any ships or boats that might stray into the blast zone on the appointed day. As the planning progressed, more organizations became interested. The U. S. Department of Fish and Wildlife and the U. S. Bureau of Commercial Fisheries became interested parties because of a concern that such an explosion would result in a large fish kill. They were granted permission to send observers to the planning meetings and to the sinking of the Coastal Mariner. The commercial fishing interests on the East Coast were unmoving in their belief that an explosion of the magnitude proposed would result in a damaging fish kill. This, despite tests which showed that an explosion at the 1,000-foot depth, the depth at which Coastal Mariner was to be touched off, would have little or no effect on fish of commercial value, which do not normally frequent those depths.
The SS Coastal Mariner was loaded at NAD Earle with 4,040 short tons, of which 512 tons were actual explosives, the balance being metal parts, containers, and lading. On each level of No. 2 hold, adjacent to mass detonation ammunition, four MK-59 Sounding Fixing And Ranging (SOFAR) bombs were positioned along with 500 pounds of TNT. The SOFAR bombs, a type of underwater sound signal, are pressure-actuated devices that were set to detonate at the 1,000-foot depth. The Coastal Mariner departed NAD Earle on 13 July 1965 and arrived at the deep water dump site early on the morning of the 14th. The final instrumentation was placed on board and by 0830 the EOD team had the sea valves open. She sank in 55 minutes. Seventeen seconds after sinking by the bow, a tremendous shock was felt and a spectacular 600-foot water spout was observed.
The explosion did not produce any significant amount of debris and the fish kill was negligible. From that standpoint the experiment was a success. To the scientific community it was somewhat of a disappointment. Due to the extremely short sinking period, East Coast seismic stations were unable to record and measure the explosion.
Yet, in retrospect, far from being a scientific failure, this experiment generated great scientific interest in the CHASE program.
On the very same day that the Coastal Mariner had gone up, the fourth CHASE ship, the SS Santiago Iglesias, commenced loading at NAD Earle. She was loaded with 8,715 tons of cargo, instrumented, and rigged for underwater explosion as her predecessor had been. The same consideration that had come to light in preparing the Coastal Mariner for scuttling had to be faced with the Santiago Iglesias, but the experience with the Coastal Mariner had shown the way. On 16 September 1965, 3 hours and 16 minutes after the sea cocks were opened, she sank. Thirty-one seconds after sinking, the cargo detonated at the prescribed depth of 1,000 feet, and ONR declared this operation a success.
The SS Isaac Van Zandt, the fifth CHASE ship, showed CHASE officials that, despite their success with Santiago Iglesias, no CHASE sinking was routine. The Van Zandt loaded at NAD Bangor, Bremerton, Washington. On 23 May 1966, en route to the deep water dump site, the tow cable parted in high seas. She was loose with 8,000 tons of cargo on board, of which about 400 tons were high explosives. The Coast Guard notified all shipping in the area of this dangerous hulk adrift, while the Navy tugs Tatnuck and Koka, hampered by the high seas, pressed the pursuit. After almost six anxious hours, the tow line was recovered and the tow continued toward the deep water dump site. A seemingly endless four hours and 31 minutes after the sea valves were open, she sank. One hundred and forty-five seconds after sinking, her cargo detonated at the prescribed depth of 4,000 feet. If, because of her unscheduled romp, the Van Zandt did not go down at the precise location the scientists had planned, she had at least blown at the designated depth.
The last instrumented CHASE ship was the SS Horace Greeley that was out-loaded from NAD Earle. She was scuttled on 28 July 1966 and detonated at 4,000 feet as scheduled, without incident. The SS Michael J. Monahan out of NAD Charleston carrying a load of over-age Polaris motors was scuttled on 30 April 1967. The SS Eric C. Gibson followed on 15 June 1967.
At this writing, four more CHASE ships are scheduled. The sinking of these ships will bring to a conclusion this series of operations. The large backlog of unusable munitions that plagued the Navy in the spring of 1964 has been disposed of, mostly as a result of Operation CHASE. In fact, two of the four scheduled sinkings will out-load only Army material. Only one of the four remaining ships will be instrumented and detonated, since, again, the other three will not carry sufficient explosive material. The SS Robert Louis Stevenson, now being loaded at NAD Bangor, will have a cargo of 5,000 tons of which 2,000 tons will be explosive matter. This operation will be the largest, non-nuclear, underwater explosion ever attempted.
Operation CHASE is a very large volume operation with 46,000 tons disposed of so far, with more to come. By reducing the multiple handling of the explosives, especially at sea, this method is inherently safer. Detonating the load after scuttling has not demonstrated that any additional risks are incurred as long as prudent precautions are taken. A bonus certainly not envisioned by the planners of CHASE is the benefit to the scientific community even though there is no way to measure the real value of the benefits. Nevertheless, important data are being obtained in the seismic and hydro-acoustic communities which cannot be obtained by any method except by large explosions at sea. Such experiments would be prohibitively expensive if it were not for the CHASE program. ONR and ARPA consider the CHASE program to be an extremely valuable scientific tool, and results obtained thus far have significantly contributed to ARPA’s nuclear detection program. There are 1,100 uneconomical, inefficient, and obsolete vessels destined for scrapping. They could only be placed in service at abnormally high cost and with only marginal assurances as to reliability. This pool should provide ships for a resumption of Operation CHASE whenever the need arises.