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F r om :To :i l l C o n n e r ; B i l l L e h r ; M a r k K S o o g e ; H a m m o n d , S t e p h e n E ; S k y B r i s to l ; p a r s o n s , R o g e r ; N a t h a l i e V a l e t t e -Si l ver ; Anastas.Paul@epa .gov; Perc iasepe.Bob@epa ,gov; Venosa .Albert@epamal l .epa .gov;A l l e n . H a r r y @ e p a m a l l. e p a . g o v ; W i Is o n . G r e g o r y @ e p a m a l l. e p a . g o v ; S a r r i . K r i s t e n ; S c o t t S m u l l e n ; Z i c h a l , H e a t h e rfl; G i t s o n , S h a n n o n ; M a r g a r e t S p r i n g ; K G r i ff is @ d o c . g o vSubject:i n a l S u b m t s s io n , O t J B u d g e tDate:uesday , August 03 , 2010 3 :21 :26 PMAttachments :i l B u d g e t d e s c r i p t to n 8 3 F I N A L d o c xThis is the copy just transmitted to the W hite House. Actual schedulefor release is not known b ut should be shortly.Mark


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Deepwater Horizon Oil BudgetBased on estim ated release of 4.9m barrels of oil

Residual includes oilthat is on or just belowthe surface as lightsheen and weatheredtar balls, has washedashore or been

c o l l e c t e d f ro m t h eshore, or is buried insand and sediments.

UnifiedCommandResponseOperations

Burned5%

Skimmed3%

ChemicallyDispersed*

8%* O i l in t h e s e 3 c a t e g o r i e s iscurrently being degradednaturally.

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BP Deepw ater Horizon O il Budget:What Happened To the Oil?Th e N ational Incident Com m and (M C) assemb led a number of interagency expert scientific teams toestimate the q uantity of BP Deepwater Horizon oil that has been released from th e well and the fate ofthat oil. Th e expertise of government scientists serving on these teams is com plemented bynongovernmental and governmental specialists reviewing the calculations and conclusions. One teamcalculated the flow rate and total oil released. Led by E nergy Secretary S teven Chu and U nited StatesG eological Survey (U SG S) Director M arcia M cN utt, this team announced on August 2, 201 0, that itestimates that a total of 4.9 m illion barrels of oil has been released from the BP Deepwater Horizon well.A s econd interagency team , led by the Department of the Interior (DOI) and the N ational Oceanic andAtm ospheric Adm inistration (N OA A) developed a tool called the Oil Budget Calculator to determinewhat h appened to the oil. Th e calculator uses the 4 9 m illion barrel estim ate as its input and uses bothdirect measurem ents and the best scientific estim ates available to date, to determ ine what has h appenedto the oil. The interagency scientific report below builds upon the calculator and sum m arizes thedisposition of the oil to date.In sum m ary, it is estimated that burning, skim m ing and direct recovery from th e wellhead remov ed onequarter (25%) of the oil released from the wellhead. One quarter (25%) of the total oil naturallyevaporated or dissolved, and just less than one quarter (24% ) was dispersed (either naturally or as aresult of operations) as m icroscopic droplets into Gulf waters. Th e residual amount just over onequarter (26% ) is either on or just below the surface as light sh een and weathered tar balls, has washedashore or been collected from the sh ore, or is buried in sand and sediments. Oil in the residual anddispersed categories is in the process of b eing degraded. The report below describes each of th esecategories and calculations. Th ese estim ates will continue to be refined as additional informationbecomes available.

Figure 1: Oil Budget - Show s current best estimates of what happened to the oil.


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Explanation of FindingsUnified Comm and R esponse Efforts: Response efforts to deal with the oil have been aggressive. Asshown in the pie chart (F igure 1), response efforts were successful in addressing 33% of the spilled oil.Th is includes oil that was c aptured directly from th e wellhead by th e riser pipe insertion tube and top hatsystem s (17% ), burning (5% ), skimm ing (3% ) and chem ical dispersion (8%). Direct capture, burningand skim m ing rem ove the oil from th e water entirely, while chem ically dispersed oil remains in thewater until it is biodegraded, as discuss ed below.Dispersion: Based on estimates, 16% of the oil dispersed naturally into the water colum n and 8% wasdispersed by th e application of chem ical dispersants on and below the surface. N atural dispersion occursas a result of the oil com ing out of the riser pipe at high speed into the water column, wh ich caused som eof the oil to spray off in sm all droplets. For the purpose of this analysis, 'dispersed oil' is defined asdroplets that are less than 100 m icrons about the diameter of a hum an hair. Oil droplets that are thissm all are neutrally buoyant and thus remain in the water colum n where they then begin to biodegrade.Chem ical dispersion also breaks the oil up into sm all droplets to keep it from corning ashore in largesurface slicks and makes it more readily available for biodegradation. Chemical dispersants were appliedat the surface and below the surface; therefore, the chem ically dispersed oil ended up both deep in thewater column and just b elow the surface. Dispersion increases the likelihood that the oil will bebiodegraded, both in the water column and at the surface. U ntil it is biodegraded, naturally or chemicallydispersed oil, even in dilute amounts, c an be toxic to vulnerable species.All of the naturally dispersed oil and some of the oil that was chemically dispersed remained well-belowthe surface in diffuse clouds wh ere it began to dissipate further and biodegrade. Previous analyses h aveshown evidence of diffuse clouds of dispersed oil between 3,300 and 4,300 feet in very lowconcentrations (parts per m illion or less), m oving in the direction of known ocean currents anddecreasing with distance from the wellhead. (citation: Federal Joint Analysis G roup Report 1 and 2 ,http://ecowatch.ncddc.noaa.gov/JAG/reports.html) . Oil that was chem ically dispersed at the surfacemoved into the top 20 feet of the water column wh ere it mixed with surrounding waters and began tobiodegrade.Ev aporation and Dissolution: It is estim ated that 25% of the oil volum e quickly and naturallyevaporated or dissolved into the water column. T he ev aporation and dissolution rate estimate is b ased onscientific research and obs ervations conducted during the Deepwater Horizon incident.Dissolution is different from dispersion. Dissolution is the process by which individual hydrocarbonm olecules from th e oil separate and dissolve into the water just as sugar can be dissolv ed in water.Dispersion is the process by which larger volumes of oil are broken down into smaller droplets of oil.Residual: After accounting for the categories that can be m easured directly or estimated (i.e., recoveryoperations, dispersion, and evaporation and dissolution), an estimated 26% remains. T his figure is acom bination of categories all of wh ich are difficult to m easure or estimate. It includes oil still on or justbelow the surface in the form of light sheen or tar balls, oil that has washed ashore or been collectedfrom the shore, and some that is buried in sand and sediments and may resurface through time. This oilhas also b egun to degrade through natural processes.


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Biodegradation: Dispersed oil in the water column and oil on the surface of th e water biodegradenaturally. W hile there is m ore analysis to be done to quantify the rate of biodegradation in the Gulf,early observations and preliminary research results from a num ber of scientists show that the oil fromthe BP Deepwater Horizon spill is biodegrading quickly. Scientists from NOAA, EPA, DOE andacadem ia are working to calculate more precise estimates of th is rate. It is well known that bacteria thatbreak down th e dispersed and weathered surface oil are abundant in the G ulf of M exico in large partbecause of the warm water, the favorable nutrient and oxygen levels, and the fac t that oil regularlyenters the Gulf of M exico through natural seeps.E xplanation of M ethods and Assum ptionsFlow R ate: The Oil Budget Calculator starts with an estimate of the c um ulative am ount of oil releasedover the course of th e spill. Th e newest estimates reflect the collaborative work and discussions of theN ational Incident Com m and's Flow R ate Technical Group (FRT G) led by U nited States G eologicalSurvey (US G S) Director M arcia M cN utt, and a team of Departm ent of Energy (DOE) scientists andengineers, led by E nergy Secretary Steven Chu. Th is group estimates that approximately 4.9 millionbarrels of oil flowed from the BP D eepwater Horizon wellhead between April 22 and July 15 , 201 0, atwhich tim e the flow of oil was suspended. Th e uncertainty of this estimate is + 10% . The pie chartabove is b ased on this group's estimate of 4.9 m illion barrels of oil.Direct M easures and Be st Estimates: Th e oil budget calculations are based on direct m easurementswherever possible and the bes t available scientific estimates where m easurements were not possible.Th e num bers for direct recovery and b urns were m easured directly and reported in daily operationalreports. The skimm ing numbers were also based on daily reported estimates. The rest of the numb erswere based on previous scientific analyses, best av ailable inform ation and a broad range of scientificexpertise. These numbers will continue to be refined based on additional information and furtheranalysis. Further information on these c alculation m ethods is av ailable in the Deepwater Horizon GulfIncident Budget Tool R eport from A ug 1, 201 0 (available online) Th e tool was created by the USGeological Survey in collaboration with US Coast G uard, NO AA and NIS T.Continued monitoring and research:Our knowledge of the oil, dispersants, ecosys tem im pacts and hum an impacts will continue to evolve.Federal agencies and m any academ ic and independent scientists are actively pursuing betterunderstanding of the fate, transport and impact of the oil. Th e federal government will continue to reportactivities, results and data to the public on a regular basis. Updates and inform ation can be found atwww.restorethegulf goy, and data from the response and m onitoring can be found atwww.geoplatform.gov.DOI, N AS A and N OAA continue to refine understanding of amounts of remaining surface oil. N OAAresponders are working with the U nified Com m and on m onitoring strategies for tar balls and near shoresubm erged oil, and researchers continue subsurface scanning and sampling to m onitor the concentration,distribution and impact of oil there. EP A and N OA A h ave carefully m onitored BP's use of dispersant inthe Gulf and continues to monitor the air, water and sediments near the shoreline for the presence ofdispersant and crude oil components with special attention to hum an health impacts. N umerousNOAA and NSF-funded academic researchers and NOAA scientists are investigating rates of biodegradation,ecosystem and wildlife impacts. DOI and DOE responders are working to ensure control of the well and


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accurate m easurement of oil released and oil remaining in the environment. DOI is leading efforts tom itigate impacts of oil to terrestrial wildlife, natural resources, and pub lic lands.Ev en though the th reat to shorelines, fish and wildlife, and ecosys tems has decreased since the cappingof the BP wellhead, federal scientists remain extremely concerned about the im pact of the spill to theGulf ecosystem . Fully understanding the im pacts of this spill on wildlife, hab itats, and natural resourcesin the G ulf region will take time and continued monitoring and research.

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