seven months.

Several incidents resulted in the injury and death of

members of the crew, and damage or loss of valuable equipment. No

estimates of the amount of gas lost have been made.

b. Oil Spills Greater Than 50 Bbl. in Size

Note that we do not entitle this section "Major" or

"Massive" or "Large" etc. Several governmental agencies have

endeavored to establish a system for oil spill size classification, i.e., the U.S. Coast Guard, U.S. Geological Survey, Environmental Protection

Agency.

Data

Because these classification systems are not similar, we choose not to adopt any of them, but instead, we believe any spill of 50 bbl. or more is significant enough to receive individual consideration. supplied by the Geological Survey for the period 1964-1973 indicate a total of 43 oil spill incidents connected with Federal OCS oil and gas operations in the Gulf of Mexico involving 50 bbl. or more of oil and

condensate.

The estimated total volume of oil spilled during this period as a

result of these incidents is slightly more than 300,000 bbl. A distribution of these 43 incidents as to type and amount spilled is presented in Fig. 46.

In the following discussion of oil spills by type, several predictions will be made by comparing the volumes of these spills and the total production of oil and condensate during the same period, 2.8 billion bbl.

(1) Pipeline Accidents

During OCS operations, more oil has been spilled

from pipeline accidents than from all other sources combined. In October of 1967, a vessel underway during a storm and with its anchor inadvertently left out, snagged and severed a pipeline about 20 miles west of the mouth of Southwest Pass, Mississippi River delta, Louisiana. The resulting spill went undetected for nearly two weeks, releasing over 160,000 bbl. of oil into the sea. In March of 1968, another anchor/ pipeline accident resulted in a 6,000 bbl. spill. In February of 1969, a pipeline leak released over 7,500 bbl. into the sea; the cause was never determined.

Beginning in 1969, several actions were undertaken to decrease this inordinately high volume of spillage per accident and to keep the frequency of recurrence low. Since 1969, the Bureau of Land Management, through administrative procedures, has required the burial of all new common carrier pipelines with a minimum of three feet of cover out to a water depth of 200 feet. Where the pipelines cross shipping fairways and anchorage areas, they must be buried at least 10 feet deep. In water depths of less than 200 feet, only the lines in the gathering system between adjacent platforms of a particular oil or gas field may remain unburied. Permits to construct such lines are granted by the Geological Survey and the decision to bury is made on a case-by-case

basis.

In connection with regulations formulated by the Office of Pipeline Safety (OPS), Department of Transportation (49 CFR Parts 192 and 195) offshore pipelines were required to be coated with tightly bonded, moisture impervious materials followed in many cases by a layer of dense concrete for mechanical and corrosion protection.

In addition

to coatings, impressed currents or sacrificial anodes were required to protect against electrolytic corrosion. The OPS regulations also require

continuous line pressure monitoring with some type of communication

system (a built-in-alarm or automatic shut-down system is normally used), and regular inspection of the pipeline route for leaks and other

irregularities.

Other features used by industry also serve to mitigate against accidents: continuous metering systems, automatic high pressure shutdowns, and remotely controlled mainline block valves that can isolate sections of a line. A more complete discussion of all of these systems is presented in Vol. 1, Sec. III. A. 4 a.

Caution should be inserted at this point. In established oil and gas fields where older lines are present, corrosion will be in a more advanced state, the line may be poorly buried if at all, and all of the above-mentioned requirements for safety and control features may not apply. In fact, industry spokesmen have estimated that 48% of all pipeline leaks occur in lines that have been in use for 15 years or more.

With all of the above information in hand, it is our conclusion that leaks of the magnitude of thousands of barrels, such as those cited from 1967-69, could not occur from any new lines resulting from this proposal, providing that existing regulations are stringently enforced and inspection procedures diligently followed. As evidence, we note that from 1970 to the present time, there have been five recorded pipeline leaks on the Gulf of Mexico OCS, resulting in a total spillage of 5,300 bbl. of oil, 5,000 of which was due to internal corrosion of a pipeline.

For the purpose of predicting the rate and size of pipeline oil spills offshore that could result from this proposed lease sale we have made

the following assumptions:

All common carrier pipelines will be routed through corridors The industry will make a sincere effort to comply with existing codes and regulations

There are no unforeseen geologic or other hazards which would lead to pipeline damage more often or severe than the levels experienced off Louisiana and Texas.

Based on these assumptions, we predict that an average of 70 bbl. per year will be spilled due to pipeline related accidents, and we predict that the maximum size of any one spill will not exceed 3,000 bbl.

The latest pipe-laying and monitoring techniques combined with modern materials and equipment should insure that the 150-300 miles of pipeline required for this sale suffer no major breaks for several years