Nov 16, 1979 - oil onshore. Beach impacts directly attibutable to the B:rrmah. Agate occurred as far as 470 kilometers (km) from the wreck near Mansfield Pass ...
Reprint from Proceedinqs of the l_991 Oil Spill- Conference, API publ. No. 4334, American Petroleum Inst., lrlash., D.C ONSHORE IMPACTS AND CLEANUP DURING THE BURMAH AGATE OIL SPILL-NOVEMBER 1979 Larry C. Thebeau and Timothy W. Kana Research Planning Institute, Inc. 806 Pavillion Avenue Columbia, South Carolina 29205 ABSTRACT: Of the 250,000 barrels (bbl) of oil spilled or consumed by
fire during the Burmah
Agate
This paper describes the extent of onshore impacts and cleanup operations during the Burtnah Agate oil spill. A chronology and information on containment operations are given in an accompanying paper in these Proceedings by Thompson et al. (1981).
spilt off Galveston,
Texas, in November 1979, 2,100 bbl eventually reached the shore. Fortunately, because of the predominance of offshore, northerly winds in November 1979, most of the oil not consumed
fire dispersed offshore or was contained and recovered at the wreck site. Daily aerial and ground surveys at reference stations were conducted to locate impacts and monitor the persistence of oil onshore. Beach impacts directly attibutable to the B:rrmah Agate occurred as far as 470 kilometers (km) from the wreck near Mansfield Pass, Texas . The first major ímpcct occurued on by
November 8 and 9 when approximately 500 bbl impacted a l0-km section ofSan Jose Island,250 km southwest ofthe wreck. Due to relative inaccessibility, and rapid recovery of the beach, no cleanup was aftempted. By November 16, 1979, less than 25 percent of the impact remained buried or on the beachface. The
heaviest onshore impact
o/ Burmah Agale oil
occurred
Novembèr 19 to 2l when up to 1,500 bbl beached along the western half of Galveston Island. Cleanup was initially by manuctl lahor and.front-end loaders; however, by November 23, the primary method of cleanup involved pooling the oil by hand labor and picking it up with vacuum trucks. This latter method considerably reduced the volume of sand retnoved from the beach. Cleanup and manicuring the beach were virtually complete by November 27. Other minor impacts of less than 50 bbl occurred sporadically during the spill from Bolivar peninsula to Brown Cedar Cut. The only known marsh impact occurred on November 9, when approximately 5 bbl coated 400 meters of .fringing marsh along Smith Point in Galveston Bay.
General setting The shoreline of Texas is composed of a series of long, thin barrier islands and peninsulas, tidal inlets, and erosional deltaic headlands. Barrier islands are separated from the mainland by large bay or lagoon systems. The coast of east Texas, which was most directly threatened by oil from the Burmah Agate, includes Bolivar Peninsula and Calveston Island to the east and west of Galveston Entrance Channel, respectively. Each land mass has a wide, fine-grained sand beach, a poorly developed foreisland dune field with some ridge and swale topography, and a back tidal channel network which drains into the bay area (McGowen et al., 1977).
In general, the geomorphology of the bay and lagoon sysrems of Texas is largely controlled by wind, wind tides, and sediment supply. During summer months, dominant sotitheasterly winds generate wave activity, which erodes northwestern shores. During winter months, when winds are predominantly from the north, just the opposite occurs.
The location of major tidal inlets along the Texas coast is strongly influenced by wind tides which are caused by prolonged winds blowing along the axes of the open bays. Major natural inlets such as San Luis Pass and Pass Cavallo are located at the southwest ends of West Bay (Galveston Island) and Matagorda Bay, respectively. Flushing of these passes is controlled by the degree of setup of local water level caused by wind tides. The migration and location of these unstabilized inlets is a result of northerly winds (Price, 1952).
Introduction The collision of the oil tanker Burmah Agatc and the freighter Mimosa 7 km southeast of Galveston Entrance on November l, 1979, resulted in the largest oil spill in U.S. waters for the year. The spill posed an immediate threat to Galveston's beaches and adjacent tidal inlets and bays but, fortunately, seasonal wind patterns transported most of the slick offshore. Of the 250,000 bbl spilled or consumed by fire between November and early January 1980, less than 2,500 bbl (l percent) evenrually reached shore. The spill occurred 5 months after the Ixtoc I blowout in Mexico which eventually impacted 150 km of the south Texas coast with up to 27,000 bbl (Gundlach et al., l98l). Experience
\{ind
and current regime. Wind that is onshore approximonths of the year is perhaps the single most important geologic agent affecting the Texas Gulf shoreline (McGowen et al., 1977). Two principal wind regimes dominate
mately
l0
(l) prevailing southeasterly winds from March through September, and (2) short-lived but strong nor_ therly winds from October through February. Predominant nor_ therly winds occur in winter due to the presence of polar air masses or "northers" that penetrate the coastal zone as fre_ quently as 15 to 20 times per year. "Northers" may last from I to 3 days with winds of 25 to 50 knots or more. On Galveston Island, waves associated with'.northers" produce a strong nearshore surface flow in a southwesterly direction. the Texas coastal zone:
I response considerably aided the monitoring, planning, and implementation of cleanup during the Burmah Agate spill. gained during the Ixtoc
139
't40 The wind regime controls nearshore and shelf surface water circulation. Southeasterly winds in spring and summer produce a northeasterly flow along the coast. In winter, predominant northerly winds cause a reversal of nearshore currents to the south. During the Burmah Agate wreck, northerly winds predominating in winter caused surface flows to the southwest for
most days during the spill. By use of a trajectory model developed by J. Galt of the National Oceanic and Atmospheric Administration (NOAA), surface circulation patterns around the Burmah Agate were monitored daily.
Current interaction at Galveslon Bntrance. Nearshore shelf currents at fhe Burmah Agate wreck site are somewhat influenced by tidal currents associated with the Galveston Entrance Channel. The entrance jetties, which extend over 2 km seaward from Galveston Island, channeled ebb currents close to the wreck site. Interaction of tidal and wave-generated currents produce a gyre (visible on high altitude photography) which causes a clockwise return flow toward East Beach along Galveston Island. This tyre helped produce entrance
oil
Onshore impacts Onshore impacts of Bur¡nah Agate oil occurred sporadically of November at several widely scattered locations along the Texas coast (Figure 1a). The heaviest impacts occurred on San Jose Island (500 bbl) on November &-9, and on Galveston Island from November 19-21 (1,000 to 1,400 bbl) (Figure lb). Light impacts occurred on November 5 on Galveston Island (
