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When the cofferdams were in place and the construction site was drained of water , excavation for the dam foundation began . For the dam to rest on solid rock , it was necessary to remove accumulated erosion soils and other loose materials in the riverbed until sound bedrock was reached . Work on the foundation excavations was completed in June 1933 . During this excavation , approximately 1 @,@ 500 @,@ 000 cu yd ( 1 @,@ 100 @,@ 000 m3 ) of material was removed . Since the dam was an arch @-@ gravity type , the side @-@ walls of the canyon would bear the force of the impounded lake . Therefore , the side @-@ walls were excavated too , to reach virgin rock as weathered rock might provide pathways for water seepage .
The men who removed this rock were called " high scalers " . While suspended from the top of the canyon with ropes , the high @-@ scalers climbed down the canyon walls and removed the loose rock with jackhammers and dynamite . Falling objects were the most common cause of death on the dam site ; the high scalers ' work thus helped ensure worker safety . One high scaler was able to save life in a more direct manner : when a government inspector lost his grip on a safety line and began tumbling down a slope towards almost certain death , a high scaler was able to intercept him and pull him into the air . The construction site had , even then , become a magnet for tourists ; the high scalers were prime attractions and showed off for the watchers . The high scalers received considerable media attention , with one worker dubbed the " Human Pendulum " for swinging co @-@ workers ( and , at other times , cases of dynamite ) across the canyon . To protect themselves against falling objects , some high scalers took cloth hats and dipped them in tar , allowing them to harden . When workers wearing such headgear were struck hard enough to inflict broken jaws , they sustained no skull damage , Six Companies ordered thousands of what initially were called " hard boiled hats " ( later " hard hats " ) and strongly encouraged their use .
The cleared , underlying rock foundation of the dam site was reinforced with grout , called a grout curtain . Holes were driven into the walls and base of the canyon , as deep as 150 feet ( 46 m ) into the rock , and any cavities encountered were to be filled with grout . This was done to stabilize the rock , to prevent water from seeping past the dam through the canyon rock , and to limit " uplift " — upward pressure from water seeping under the dam . The workers were under severe time constraints due to the beginning of the concrete pour , and when they encountered hot springs or cavities too large to readily fill , they moved on without resolving the problem . A total of 58 of the 393 holes were incompletely filled . After the dam was completed and the lake began to fill , large numbers of significant leaks into the dam caused the Bureau of Reclamation to look into the situation . It found that the work had been incompletely done , and was based on less than a full understanding of the canyon 's geology . New holes were drilled from inspection galleries inside the dam into the surrounding bedrock . It took nine years ( 1938 – 47 ) under relative secrecy to complete the supplemental grout curtain .
= = = Concrete = = =
The first concrete was poured into the dam on June 6 , 1933 , 18 months ahead of schedule . Since concrete heats and contracts as it cures , the potential for uneven cooling and contraction of the concrete posed a serious problem . Bureau of Reclamation engineers calculated that if the dam was built in a single continuous pour , the concrete would take 125 years to cool and the resulting stresses would cause the dam to crack and crumble . Instead , the ground where the dam was to rise was marked with rectangles , and concrete blocks in columns were poured , some as large as 50 ft square ( 15 m ) and 5 feet ( 1 @.@ 5 m ) high . Each five @-@ foot form contained a series of 1 @-@ inch ( 25 mm ) steel pipes through which first cool river water , then later ice @-@ cold water from a refrigeration plant was run . When an individual block had cured and had stopped contracting , the pipes were filled with grout . Grout was also used to fill the hairline spaces between columns , which were grooved to increase the strength of the joins .
The concrete was delivered in huge steel buckets 7 feet high ( 2 @.@ 1 m ) and almost 7 feet in diameter ; Crowe was awarded two patents for their design . These buckets , which weighed 20 short tons ( 18 t ) when full , were filled at two massive concrete plants on the Nevada side , and were delivered to the site in special railcars . The buckets were then suspended from aerial cableways , which were used to deliver the bucket to a specific column . As the required grade of aggregate in the concrete differed depending on placement in the dam ( from pea @-@ sized gravel to 9 @-@ inch or 23 cm stones ) , it was vital that the bucket be maneuvered to the proper column . When the bottom of the bucket opened up , disgorging 8 cu yd ( 6 @.@ 1 m3 ) of concrete , a team of men worked it throughout the form . Although there are myths that men were caught in the pour and are entombed in the dam to this day , each bucket only deepened the concrete in a form by an inch , and Six Companies engineers would not have permitted a flaw caused by the presence of a human body .
A total of 3 @,@ 250 @,@ 000 cubic yards ( 2 @,@ 480 @,@ 000 m3 ) of concrete was used in the dam before concrete pouring ceased on May 29 , 1935 . In addition , 1 @,@ 110 @,@ 000 cu yd ( 850 @,@ 000 m3 ) were used in the power plant and other works . More than 582 miles ( 937 km ) of cooling pipes were placed within the concrete . Overall , there is enough concrete in the dam to pave a two @-@ lane highway from San Francisco to New York . Concrete cores were removed from the dam for testing in 1995 ; they showed that " Hoover Dam 's concrete has continued to slowly gain strength " and the dam is composed of a " durable concrete having a compressive strength exceeding the range typically found in normal mass concrete " . Hoover Dam concrete is not subject to alkali – silica reaction ( ASR ) as the Hoover Dam builders happened to use nonreactive aggregate , unlike that at downstream Parker Dam , where ASR has caused measurable deterioration .
= = = Dedication and completion = = =
With most work finished on the dam itself ( the powerhouse remained uncompleted ) , a formal dedication ceremony was arranged for September 30 , 1935 , to coincide with a western tour being made by President Franklin D. Roosevelt . The morning of the dedication , it was moved forward three hours from 2 p.m. Pacific time to 11 a.m. ; this was done because Secretary of the Interior Harold L. Ickes had reserved a radio slot for the President for 2 p.m. but officials did not realize until the day of the ceremony that the slot was for 2 p.m. Eastern Time . Despite the change in the ceremony time , and temperatures of 102 ° F ( 39 ° C ) , 10 @,@ 000 people were present for the President 's speech in which he avoided mentioning the name of former President Hoover , who was not invited to the ceremony . To mark the occasion , a three @-@ cent stamp was issued by the United States Post Office Department — bearing the name " Boulder Dam " , the official name of the dam between 1933 and 1947 . After the ceremony , Roosevelt made the first visit by any American president to Las Vegas .
Most work had been completed by the dedication , and Six Companies negotiated with the government through late 1935 and early 1936 to settle all claims and arrange for the formal transfer of the dam to the Federal Government . The parties came to an agreement and on March 1 , 1936 , Secretary Ickes formally accepted the dam on behalf of the government . Six Companies was not required to complete work on one item , a concrete plug for one of the bypass tunnels , as the tunnel had to be used to take in irrigation water until the powerhouse went into operation .
= = = Construction deaths = = =
There were 112 deaths associated with the construction of the dam . The first was J. G. Tierney , a surveyor who drowned on December 20 , 1922 , while looking for an ideal spot for the dam . Ninety @-@ six of the deaths occurred during construction at the site . Of the 112 fatalities , 91 were Six Companies employees , three were BOR employees , and one was a visitor to the site , with the remainder employees of various contractors not part of Six Companies .
Not included in the official fatalities number were deaths that were recorded as pneumonia . Workers alleged that this diagnosis was a cover for death from carbon monoxide poisoning , brought on by the use of gasoline @-@ fueled vehicles in the diversion tunnels , and a classification used by Six Companies to avoid paying compensation claims . The site 's diversion tunnels frequently reached 140 ° F ( 60 ° C ) , enveloped in thick plumes of vehicle exhaust gases . A total of 42 workers were recorded as having died from pneumonia ; none were listed as having died from carbon monoxide poisoning . No deaths of non @-@ workers from pneumonia were recorded in Boulder City during the construction period .
= = = Architectural style = = =
The initial plans for the facade of the dam , the power plant , the outlet tunnels and ornaments clashed with the modern look of an arch dam . The Bureau of Reclamation , more concerned with the dam 's functionality , adorned it with a Gothic @-@ inspired balustrade and eagle statues . This initial design was criticized by many as being too plain and unremarkable for a project of such immense scale , so Los Angeles @-@ based architect Gordon B. Kaufmann , then the supervising architect to the Bureau of Reclamation , was brought in to redesign the exteriors . Kaufmann greatly streamlined the design , and applied an elegant Art Deco style to the entire project . He designed sculptured turrets rising seamlessly from the dam face and clock faces on the intake towers set for the time in Nevada and Arizona — the two states are in different time zones , but as Arizona does not observe Daylight Saving Time , the clocks display the same time for more than half the year .
At Kaufmann 's request , Denver artist Allen Tupper True was hired to handle the design and decoration of the walls and floors of the new dam . True 's design scheme incorporated motifs of the Navajo and Pueblo tribes of the region . Although some initially were opposed to these designs , True was given the go @-@ ahead and was officially appointed consulting artist . With the assistance of the National Laboratory of Anthropology , True researched authentic decorative motifs from Indian sand paintings , textiles , baskets and ceramics . The images and colors are based on Native American visions of rain , lightning , water , clouds , and local animals — lizards , serpents , birds — and on the Southwestern landscape of stepped mesas . In these works , which are integrated into the walkways and interior halls of the dam , True also reflected on the machinery of the operation , making the symbolic patterns appear both ancient and modern .
With the agreement of Kaufmann and the engineers , True also devised an innovative color @-@ coding for the pipes and machinery , which was implemented throughout all BOR projects . True 's consulting artist job lasted through 1942 ; it was extended so he could complete design work for the Parker , Shasta and Grand Coulee dams and power plants . True 's work on the Hoover Dam was humorously referred to in a poem published in The New Yorker , part of which read , " lose the spark , and justify the dream ; but also worthy of remark will be the color scheme " .
Complementing Kaufmann and True 's work , the Norwegian @-@ born , naturalized American sculptor Oskar J.W. Hansen designed many of the sculptures on and around the dam . His works include the monument of dedication plaza , a plaque to memorialize the workers killed and the bas @-@ reliefs on the elevator towers . In his words , Hansen wanted his work to express " the immutable calm of intellectual resolution , and the enormous power of trained physical strength , equally enthroned in placid triumph of scientific accomplishment " , because " [ t ] he building of Hoover Dam belongs to the sagas of the daring . " Hansen 's dedication plaza , on the Nevada abutment , contains a sculpture of two winged figures flanking a flagpole .
Surrounding the base of the monument is a terrazzo floor embedded with a " star map " . The map depicts the Northern Hemisphere sky at the moment of President Roosevelt 's dedication of the dam . This is intended to help future astronomers , if necessary , calculate the exact date of dedication . The 30 @-@ foot @-@ high ( 9 @.@ 1 m ) bronze figures , dubbed " Winged Figures of the Republic " , were each formed in a continuous pour . To put such large bronzes into place without marring the highly polished bronze surface , they were placed on ice and guided into position as the ice melted . Hansen 's bas @-@ relief on the Nevada elevator tower depicts the benefits of the dam : flood control , navigation , irrigation , water storage , and power . The bas @-@ relief on the Arizona elevator depicts , in his words , " the visages of those Indian tribes who have inhabited mountains and plains from ages distant . "
= = Operation = =
= = = Power plant and water demands = = =
Excavation for the powerhouse was carried out simultaneously with the excavation for the dam foundation and abutments . A U @-@ shaped structure located at the downstream toe of the dam , its excavation was completed in late 1933 with the first concrete placed in November 1933 . Filling of Lake Mead began February 1 , 1935 , even before the last of the concrete was poured that May . The powerhouse was one of the projects uncompleted at the time of the formal dedication on September 30 , 1935 — a crew of 500 men remained to finish it and other structures . To make the powerhouse roof bombproof , it was constructed of layers of concrete , rock , and steel with a total thickness of about 3 @.@ 5 feet ( 1 @.@ 1 m ) , topped with layers of sand and tar .
In the latter half of 1936 , water levels in Lake Mead were high enough to permit power generation , and the first three Allis Chalmers built Francis turbine @-@ generators , all on the Nevada side , began operating . In March 1937 , one more Nevada generator went online and the first Arizona generator by August . By September 1939 , four more generators were operating , and the dam 's power plant became the largest hydroelectricity facility in the world . The final generator was not placed in service until 1961 , bringing the maximum generating capacity to 1 @,@ 345 megawatts at the time . Original plans called for 16 large generators , eight on each side of the river , but two smaller generators were installed instead of one large one on the Arizona side for a total of 17 . The smaller generators were used to serve smaller communities at a time when the output of each generator was dedicated to a single municipality , before the dam 's total power output was placed on the grid and made arbitrarily distributable . The present contracts for the sale of electricity expire in 2017 .
Before water from Lake Mead reaches the turbines , it enters the intake towers and then four gradually narrowing penstocks which funnel the water down towards the powerhouse . The intakes provide a maximum hydraulic head ( water pressure ) of 590 ft ( 180 m ) as the water reaches a speed of about 85 mph ( 140 km / h ) . The entire flow of the Colorado River passes through the turbines . The spillways and outlet works ( jet @-@ flow gates ) are rarely used . The jet @-@ flow gates , located in concrete structures 180 feet ( 55 m ) above the river , and also at the outlets of the inner diversion tunnels at river level , may be used to divert water around the dam in emergency or flood conditions , but have never done so , and in practice are only used to drain water from the penstocks for maintenance . Following an uprating project from 1986 to 1993 , the total gross power rating for the plant , including two 2 @.@ 4 megawatt Pelton turbine @-@ generators that power Hoover Dam 's own operations is a maximum capacity of 2080 megawatts . The annual generation of Hoover Dam varies . The maximum net generation was 10 @.@ 348 TWh in 1984 , and the minimum since 1940 was 2 @.@ 648 TWh in 1956 . The average power generated was 4 @.@ 2 TWh / year for 1947 @-@ 2008 . In 2015 , the dam generated 3 @.@ 6 TWh . To lower the minimum power pool elevation from 1 @,@ 050 to 950 feet ( 320 to 290 m ) , five wide @-@ head turbines , designed to work efficiently with less flow , will be online by 2017 . Due to lack of water , the dam mostly provides power only during periods of peak demand .
Control of water was the primary concern in the building of the dam . Power generation has allowed the dam project to be self @-@ sustaining : proceeds from the sale of power repaid the 50 @-@ year construction loan , and those revenues also finance the multimillion @-@ dollar yearly maintenance budget . Power is generated in step with and only with the release of water in response to downstream water demands .
Lake Mead and downstream releases from the dam also provide water for both municipal and irrigation uses . Water released from the Hoover Dam eventually reaches several canals . The Colorado River Aqueduct and Central Arizona Project branch off Lake Havasu while the All @-@ American Canal is supplied by the Imperial Dam . In total , water from the Lake Mead serves 18 million people in Arizona , Nevada and California and supplies the irrigation of over 1 @,@ 000 @,@ 000 acres ( 400 @,@ 000 ha ) of land .
= = = = Power distribution = = = =
Electricity from the dam 's powerhouse was originally sold pursuant to a fifty @-@ year contract , authorized by Congress in 1934 , which ran from 1937 to 1987 . In 1984 , Congress passed a new statute which set power allocations from the dam from 1987 to 2017 . The powerhouse was run under the original authorization by the Los Angeles Department of Water and Power and Southern California Edison ; in 1987 , the Bureau of Reclamation assumed control . In 2011 , Congress enacted legislation extending the current contracts until 2067 , after setting aside 5 % of Hoover Dam 's power for sale to Native American tribes , electric cooperatives , and other entities . The new arrangement will begin in 2017 . The Bureau of Reclamation reports that the energy generated is allocated as follows :
= = = Spillways = = =
The dam is protected against over @-@ topping by two spillways . The spillway entrances are located behind each dam abutment , running roughly parallel to the canyon walls . The spillway entrance arrangement forms a classic side @-@ flow weir with each spillway containing four 100 @-@ foot @-@ long ( 30 m ) and 16 @-@ foot @-@ wide ( 4 @.@ 9 m ) steel @-@ drum gates . Each gate weighs 5 @,@ 000 @,@ 000 pounds ( 2 @,@ 300 @,@ 000 kg ) and can be operated manually or automatically . Gates are raised and lowered depending on water levels in the reservoir and flood conditions . The gates are unable to entirely prevent water from entering the spillways but are able to maintain an extra 16 ft ( 4 @.@ 9 m ) of lake level . Water flowing over the spillways drops dramatically into 600 @-@ foot @-@ long ( 180 m ) , 50 @-@ foot @-@ wide ( 15 m ) spillway tunnels before connecting to the outer diversion tunnels , and reentering the main river channel below the dam . This complex spillway entrance arrangement combined with the approximate 700 @-@ foot ( 210 m ) elevation drop from the top of the reservoir to the river below was a difficult engineering problem and posed numerous design challenges . Each spillway 's capacity of 200 @,@ 000 cu ft / s ( 5 @,@ 700 m3 / s ) was empirically verified in post @-@ construction tests in 1941 .
The large spillway tunnels have been used only twice , for testing in 1941 and because of flooding in 1983 . During both times , when inspecting the tunnels after the spillways were used , engineers found major damage to the concrete linings and underlying rock . The 1941 damage was attributed to a slight misalignment of the tunnel invert ( or base ) , which caused cavitation , a phenomenon in fast @-@ flowing liquids in which vapor bubbles collapse with explosive force . In response to this finding , the tunnels were patched with special heavy @-@ duty concrete and the surface of the concrete was polished mirror @-@ smooth . The spillways were modified in 1947 by adding flip buckets , which both slow the water and decrease the spillway 's effective capacity , in an attempt to eliminate conditions thought to have contributed to the 1941 damage . The 1983 damage , also due to cavitation , led to the installation of aerators in the spillways . Tests at Grand Coulee Dam showed that the technique worked , in principle .
= = = Roadway and tourism = = =
There are two lanes for automobile traffic across the top of the dam , which formerly served as the Colorado River crossing for U.S. Route 93 . In the wake of the September 11 , 2001 terrorist attacks , authorities expressed security concerns and the Hoover Dam Bypass project was expedited . Pending the completion of the bypass , restricted traffic was permitted over Hoover Dam . Some types of vehicles were inspected prior to crossing the dam while semi @-@ trailer trucks , buses carrying luggage , and enclosed @-@ box trucks over 40 ft ( 12 m ) long were not allowed on the dam at all , and were diverted to U.S. Route 95 or Nevada State Routes 163 / 68 . The four @-@ lane Hoover Dam Bypass opened on October 19 , 2010 . It includes a composite steel and concrete arch bridge , the Mike O 'Callaghan – Pat Tillman Memorial Bridge , 1 @,@ 500 ft ( 460 m ) downstream from the dam . With the opening of the bypass , through traffic is no longer allowed across Hoover Dam , dam visitors are allowed to use the existing roadway to approach from the Nevada side and cross to parking lots and other facilities on the Arizona side .
Hoover Dam opened for tours in 1937 after its completion , but following Japan 's attack on Pearl Harbor on December 7 , 1941 , it was closed to the public when the United States entered World War II , during which only authorized traffic , in convoys , was permitted . After the war , it reopened September 2 , 1945 , and by 1953 , annual attendance had risen to 448 @,@ 081 . The dam closed on November 25 , 1963 and March 31 , 1969 , days of mourning in remembrance of Presidents Kennedy and Eisenhower . In 1995 , a new visitors ' center was built , and the following year , visits exceeded one million for the first time . The dam closed again to the public on September 11 , 2001 ; modified tours were resumed in December and a new " Discovery Tour " was added the following year . Today , nearly a million people per year take the tours of the dam offered by the Bureau of Reclamation . Increased security concerns by the government have led to most of the interior structure being inaccessible to tourists . As a result , few of True 's decorations can now be seen by visitors .
= = Environmental impact = =
The changes in water flow and use caused by Hoover Dam 's construction and operation have had a large impact on the Colorado River Delta . The construction of the dam has been credited as causing the decline of this estuarine ecosystem . For six years after the construction of the dam , while Lake Mead filled , virtually no water reached the mouth of the river . The delta 's estuary , which once had a freshwater @-@ saltwater mixing zone stretching 40 miles ( 64 km ) south of the river 's mouth , was turned into an inverse estuary where the level of salinity was higher close to the river 's mouth .
The Colorado River had experienced natural flooding before the construction of the Hoover Dam . The dam eliminated the natural flooding , which threatened many species adapted to the flooding , including both plants and animals . The construction of the dam devastated the populations of native fish in the river downstream from the dam . Four species of fish native to the Colorado River , the Bonytail chub , Colorado pikeminnow , Humpback chub , and Razorback sucker , are listed as endangered .
= = Naming controversy = =
During the years of lobbying leading up to the passage of legislation authorizing the dam in 1928 , the press generally referred to the dam as " Boulder Dam " or as " Boulder Canyon Dam " , even though the proposed site had shifted to Black Canyon . The Boulder Canyon Project Act of 1928 ( BCPA ) never mentioned a proposed name or title for the dam . The BCPA merely allows the government to " construct , operate , and maintain a dam and incidental works in the main stream of the Colorado River at Black Canyon or Boulder Canyon " .
When Secretary Wilbur spoke at the ceremony starting the building of the railway between Las Vegas and the dam site on September 17 , 1930 , he named the dam " Hoover Dam " , citing a tradition of naming dams after Presidents , though none had been so honored during their terms of office . Wilbur justified his choice on the ground that Hoover was " the great engineer whose vision and persistence ... has done so much to make [ the dam ] possible " . One writer complained in response that " the Great Engineer had quickly drained , ditched , and dammed the country . "
After Hoover 's election defeat in 1932 and the accession of the Roosevelt administration , Secretary Ickes ordered on May 13 , 1933 that the dam be referred to as " Boulder Dam " . Ickes stated that Wilbur had been imprudent in naming the dam after a sitting president , that Congress had never ratified his choice , and that it had long been referred to as Boulder Dam . Unknown to the general public , Attorney General Homer Cummings informed Ickes that Congress had indeed used the name " Hoover Dam " in five different bills appropriating money for construction of the dam . The official status this conferred to the name " Hoover Dam " had been noted on the floor of the House of Representatives by Congressman Edward T. Taylor of Colorado on December 12 , 1930 , but was likewise ignored by Ickes .
When Ickes spoke at the dedication ceremony on September 30 , 1935 , he was determined , as he recorded in his diary , " to try to nail down for good and all the name Boulder Dam . " At one point in the speech , he spoke the words " Boulder Dam " five times within thirty seconds . Further , he suggested that if the dam were to be named after any one person , it should be for California Senator Hiram Johnson , a lead sponsor of the authorizing legislation . Roosevelt also referred to the dam as Boulder Dam , and the Republican @-@ leaning Los Angeles Times , which at the time of Ickes ' name change had run an editorial cartoon showing Ickes ineffectively chipping away at an enormous sign " HOOVER DAM , " reran it showing Roosevelt reinforcing Ickes , but having no greater success .
In the following years , the name " Boulder Dam " failed to fully take hold , with many Americans using both names interchangeably and mapmakers divided as to which name should be printed . Memories of the Great Depression faded , and Hoover to some extent rehabilitated himself through good works during and after World War II . In 1947 , a bill passed both Houses of Congress unanimously restoring the name " Hoover Dam . " Ickes , who was by then a private citizen , opposed the change , stating , " I didn 't know Hoover was that small a man to take credit for something he had nothing to do with . "
= Tropical Storm Abby ( 1964 ) =
Tropical Storm Abby was an exceptionally small tropical cyclone that had minor effects across Southeast Texas in early August 1964 . Forming as a tropical depression out of a trough south of Louisiana on August 5 , the system moved generally westward . It was not until August 7 that the system began to organize . That day , an eye rapidly formed within the system and it became a tropical storm just 60 mi ( 95 km ) southeast of Galveston , Texas . Soon thereafter , a weather reconnaissance plane reported a barometric pressure of 1000 mbar ( hPa ; 29 @.@ 53 inHg ) at the storm 's center . Around 18 : 00 UTC ( 1 : 00 p.m. CDT ) , the newly named Abby attained peak winds of 65 mph ( 100 km / h ) . It subsequently made landfall near Matagorda , Texas four hours later . Once onshore gradual weakening ensued , though a brief period of re @-@ organization delayed its dissipation . Abby degenerated into an area of showers on August 8 southwest of San Antonio , Texas .
Prior to Abby 's landfall in Texas , gale warnings were issued for the coast and residents on Matagorda Island were evacuated . Overall , the storm 's impacts were limited due to its small size . Only two structures sustained damage in Matagorda , one being destroyed by a possible tornado , and the remaining effects resulted from flooding in Jackson and Victoria Counties . Total damage from the storm was estimated at $ 750 @,@ 000 with the majority stemming from crops .
= = Meteorological history = =
On August 5 , 1964 , a weak trough emerged from Florida over the northeastern Gulf of Mexico . According to the Atlantic hurricane database ( referred to as HURDAT ) , the system developed into a tropical depression by 18 : 00 UTC ( 1 : 00 p.m. CDT ) that day , with its center located roughly 160 mi ( 260 km ) south @-@ southeast of the Mississippi River Delta . Moving generally west , the system exhibited no signs of further development as it neared the Texas coastline . However , on August 7 , radar images from Brownsville , Galveston , Lake Charles , and Victoria showed an abrupt increase in organization . During the afternoon hours , banding features consolidated around a developing eye and weather reconnaissance planes were dispatched to the system . Forecasters initially mistook the eye as a hook echo @-@ type feature at the end of a squall line . It is estimated that the depression became a tropical storm by 12 : 00 UTC ( 7 : 00 a.m. CDT ) , roughly 60 mi ( 95 km ) southeast of Galveston , Texas . Operationally , the system was not even monitored as a depression this time , with the classification and naming of Tropical Storm Abby occurring at 16 : 00 UTC ( 11 : 00 a.m. CDT ) on August 7 .
Abby was an unusually small storm , with its entire circulation being far less than 100 mi ( 160 km ) in diameter . Around 16 : 00 UTC ( 11 : 00 a.m. CDT ) on August 7 , reconnaissance measured a central barometric pressure of 1000 mbar ( hPa ; 29 @.@ 53 inHg ) within Abby , the lowest in relation to the system . They also reported peak winds of 85 mph ( 140 km / h ) in squalls , which would rank as a Category 1 hurricane on the modern @-@ day Saffir – Simpson hurricane wind scale . These winds were seen to be an overestimate by forecasters and discarded , however . The system attained its maximum winds of 65 mph ( 100 km / h ) by 18 : 00 UTC ( 1 : 00 p.m. CDT ) and subsequently made landfall just northeast of Matagorda , Texas at 22 : 00 UTC ( 5 : 00 p.m. CDT ) . Irvin Velbrecht , a forecaster at the Weather Bureau ( now known as the National Weather Service ) in Galveston , described the storm as a " perfectly miniature hurricane . " Despite moving onshore , Abby 's core continued to organize and it developed a closed eyewall roughly three hours later . Thereafter the storm began to gradually weaken , passing over Edna around 02 : 00 UTC on August 8 ( 9 : 00 p.m. CDT on August 7 ) . Weakening to a depression hours later , Abby ultimately degenerated into an area of showers and dissipated southwest of San Antonio by 12 : 00 UTC ( 7 : 00 a.m. CDT ) .
= = Preparations and impact = =
Owing to the abrupt nature of Abby 's development on August 7 , residents had little time to prepare for the storm . According to Irvin Velbrecht , " in the absence of aircraft reconnaissance and radar information , two reasonably new tools in storm detection , Abby could well have formed and approached the shore before knowledge of a tropical storm was gained . " Gale warnings were raised from Galveston to San Antonio immediately following the storm 's formation and were kept in place through the morning of August 8 . Evacuation orders were issued for Matagorda Island and most complied , with some deciding to remain at their homes . Personnel at Matagorda Island Air Force Base were evacuated to Victoria . Red Cross facilities were readied and public shelters were opened in the area . At the mouth of the Colorado River , seagoing vessels were tied down with extra rope . Within the Weather Bureau , members of the Galveston office were the first to notice the system and relayed to the other offices in the area to attune their radars to follow the system .
Abby 's small size resulted in its effects being limited to areas within the immediate track . Sustained winds of 45 mph ( 75 km / h ) with gusts to 65 mph ( 100 km / h ) were measured by the Army Corps of Engineers in Matagorda . Near the town , a possible tornado unroofed a barn and tossed the structure 225 ft ( 69 m ) ; this building previously had withstood the effects of Hurricane Carla in 1961 . Winds estimated at 50 mph ( 80 km / h ) tore part of the roof off a fishing warehouse in Matagorda itself . Along the coast , tides ranged from 2 to 4 ft ( 0 @.@ 61 to 1 @.@ 22 m ) above normal from Matagorda to Freeport . Four men and five dogs required rescue after their vessel became stranded on the Colorado River .
Heavy rains accompanied the system across Texas . Most areas along the immediate track received at least 3 to 5 in ( 76 to 127 mm ) of rain , with a peak value of 6 @.@ 14 in ( 156 mm ) recorded at the Victoria International Airport . The hardest hit areas were in Jackson and Victoria counties where the heaviest rains fell . In these areas , flooding and strong winds damaged the cotton and rice crops ; however , effects of the rice crop were more limited due to losses from earlier storms as well as ongoing harvesting . Some flooding also took place across the Atascosa River watershed , but no damage resulted . Overall , property damage was estimated at $ 150 @,@ 000 while agricultural losses reached $ 600 @,@ 000 .
= 7 Independent Company ( Rhodesia ) =
7 Independent Company ( 7 Indep Coy ; French : 7ème Compagnie indépendante ) was a short @-@ lived company of francophone volunteers in the Rhodesian Army during the Rhodesian Bush War . Numbering about 200 men at its peak , it was unique in the history of the Rhodesian Army as an exclusively expatriate unit . It existed between November 1977 and May 1978 as a company in the 1st Battalion , the Rhodesia Regiment , and served two counter @-@ insurgency tours on Operation Hurricane in north @-@ eastern Rhodesia ( today Zimbabwe ) .
During the Bush War , the Rhodesian Army augmented its ranks with foreign volunteers , who were accepted into regular regiments with the same pay and conditions of service as locals . Most foreign recruits enlisted in the Rhodesian Light Infantry ( RLI ) , which launched an overseas recruitment programme in 1974 , but required successful applicants to speak good English . The Army attempted to alleviate the strain on its troops during late 1977 by recruiting French @-@ speakers as well , and formed a designated company in the Rhodesia Regiment for them . The regiment already had six independent companies , so the francophone unit became 7 Independent Company .
The company 's men , a mixture of former French paratroopers , ex @-@ Foreign Legionnaires and young adventurers , had trouble from the start integrating with the Rhodesian forces , and became unsettled by the respective ranks they were given in the Rhodesian Army . In an attempt to raise their morale and create a strong esprit de corps , the Army issued them beret insignias backed with the French tricolour and allowed them to raise the flag of France alongside that of Rhodesia each morning . Apparently under the impression that they had signed up as highly paid mercenaries , many of the French troopers returned home after their first bush trip , unhappy to have received no more money than a regular Rhodesian soldier .
On operations their performance was generally below par , but the Frenchmen were involved in some successful actions during February and early March 1978 . Their oppressive treatment of the black villagers they encountered made them very unpopular in the operational area . The Rhodesians quickly deemed the experiment a failure and following a series of disasters for the company during the latter part of its second tour , including two friendly fire incidents and several fatalities , it was disbanded in May 1978 . Forces led by one of its members , Bob Denard , later that month executed a coup d 'état in the Comoros with French , Rhodesian and South African governmental support .
= = Background = =
Following a dispute with the British government regarding terms for the granting of full independence , the predominantly white minority government of the self @-@ governing colony of Rhodesia ( or Southern Rhodesia ) , led by Ian Smith , unilaterally declared independence on 11 November 1965 . Britain and the United Nations refused to recognise this and each imposed economic sanctions on Rhodesia . Meanwhile , the country 's two most prominent communist @-@ backed black nationalist groups , the Zimbabwe African National Union and the Zimbabwe African People 's Union , mobilised their respective guerrilla armies , the Zimbabwe African National Liberation Army ( ZANLA ) and the Zimbabwe People 's Revolutionary Army ( ZIPRA ) , for what they called the " Second Chimurenga " , with the goal of overthrowing the government and introducing black majority rule .
The Rhodesian Bush War was the result , beginning in earnest on 21 December 1972 when ZANLA attacked Altena and Whistlefield Farms near Centenary in the country 's north @-@ east . The Rhodesian Security Forces launched Operation Hurricane in response and fought back strongly , reducing the number of guerrillas active within the country to under 300 by December 1974 . In the period October – November 1974 , they killed more nationalist fighters than in the previous two years combined . However , a South African @-@ brokered ceasefire , which the security forces respected and the insurgents ignored , helped the nationalists to win back ground . By 1977 there were 2 @,@ 500 guerrillas operating in Rhodesia , with several times that number in training abroad .
The Rhodesian Army , though mostly made up of local men , also included some foreign volunteers , who were integrated into regular units under the same salary and conditions of service . Almost all of the foreigners served in the Rhodesian Light Infantry ( RLI ) , a heliborne commando battalion with a glamorous international reputation . The RLI initiated a major overseas recruitment drive in 1974 , targeting potential volunteers from Europe , Oceania and the Americas , and requiring successful applicants to speak good English . This campaign was bearing considerable fruit by May 1976 , when the RLI 's largest ever intake included more foreign volunteers than any before , and the enlisting of men from overseas into the RLI would increase yet further . By 1977 – 78 there were around 1 @,@ 500 foreigners in the Rhodesian forces . However , the Rhodesian Army remained stretched and low on manpower .
= = Formation and training = =
The idea for a francophone unit came from a French national , François Cramer , who had business interests and connections in Rhodesia . He proposed it to Major @-@ General Sandy MacLean , then the Rhodesian Army 's second @-@ in @-@ command , while they were visiting France together . MacLean relayed the idea to the General Staff in Salisbury , which decided in late 1977 to form a " French battalion " to alleviate the strain on its regular units . A Rhodesian officer of French extraction , Cyril Bernard , warned his superiors strongly against the scheme , but was ultimately himself sent to France to start the project . On the way he stopped in Zurich , Switzerland , where MacLean gave him final approval for the operation and a budget of US $ 30 @,@ 000 . They resolved to recruit mainly in Paris and Lyon . Bernard then entered France and renewed old connections from the French military academy at Saint @-@ Cyr .