ML20125D083

Transcript of 791022 Testimony Before House Subcommittee on Energy & Environ Re Failure of Dam at United Nuclear Corp U Mill Tailings Disposal Site at Church Rock,Nm

ML20125D083
Person / Time
Issue date:	10/22/1979
From:	Dircks W NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
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TESTIMCNY OF g WILLIAM J. DIRCKS, DIRECTOR OFFICE CF NUCLEAP, MATERIAL SAFETY AND SAFEGUARDS' i

U.S. NUCLEAR REGULATORY COMMISSION i

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r SEFCRE THE -

SUBCCF.MITTEE 3 ENERGY AND THE E:!V:R0" MENT, CF THE COMMITTEE CN INTERIOR AND INSULA.R AFFA:RS CCTOBER 22, 1979 .

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.. J I am pleasec to be here today to discuss with you the Nuclear Regulatory Commission's ("RC) activities regarding the failure of the dam at the United Nuclear Corporation's (UNC) uranium mill tailings disposal site at Church ,

Rock, New Mexico. In this . testimony I will address each of the major areas I of interest outlined in your September 19, 1979 letter to Chaiman Hendrie asking us to appear today at this hearing.

The United Nuclear uranium milling operation was licensed by the State of New Mexico in May 1977. New Mexico is an Agreement Sta'te operating under terms and conditions of an, agreement signed on Acril 3,1974, authorized unoer Section 274 of the Atomic Energy Act of 1954.

The accident at the site occurred en July 15,*1979. Tne State Official s notified NRC!s Cffice cf State Programs cf the aedident on July 16,1979, and on J.uly 17, 1979, the State Environmental improvement Division requested NRC technical assistance in' evaluating the accident and in aiding the State in dealing with the public health hazards resulting from the accident. We responded oy dispatching technical staff to the State on July 13, 1979 and we have continued our effort up to the present.

In the matter of this accident, we are participating not only as a result of the State's request for technical assistance but also as an agency exercising joint regulatory jurisdicticn. This joint jurisdictional role for the NRC is a result of the Commission's cetermination that the Uranium Mill Tailings Radiation Control Act of 1978 requires NRC/ State concurrent jurisdiction over uranium miT1 tailings in Agreement States.

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khf Ak At the :nset, we chose not to issue orders to the mill operator cencerning cperation of the mill or regarding cleanup cperation. We were .

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- agreecle with the State taking the lead in dealing with the operators as long' as we were assured that cur regulatory responsibilities were considered in Sta:e acticns. As I will note later, the ti:e did c:me on October 12, 1979, that N felt that the issuance of an crder by the NRC was necessary.  !

Tne se::e cf cur activities regarding the accident and its aftermath [

hus far incl: des . preliminary. evaluations of the probable cause of the breach in :ne cam,.:re plans :roposed by the operators to repair the cam, the ,

overal" integri y of :ne em'cankment system, and the clean-up and cecontaminat' ion of :ne affec &d area. 'ae are using net only direct NRC staff cut also our ,

geotecnnical consultar.:s. We are carrying out cur activities in conjunction with' personnai from the licensee, the State of New Mexico, and the Albuquerque Offi:e of the U.S.. Arry Corps of Engineers, who had been callec in by Governor King, and the U.S. Environmental Protection Agency.

'ne have reviewed the cc:pary's evriuations of the probable cause of the acci:ent anc generally c:ncur wi:h the reported findings. Tne dam was  ;

loca:e: on a site centaining alluvial soils overlying bedrock ha.ving an L irregu. ar surface. Cepths of alluviu= ranged from less than 20 feet up to a maxt:c= of accut 100 fee:.

C:nsolidation tas:s were cenducted on samples of the alluvial soils  :

duri g :ne precenstruction design phase and amer construction of the sta-ter [

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.. a e cankment. These tests indicated that settlement cf about 5 percen: would result from the loading of the embankment under dry conditiens. After addition of water, additional settlement ranging from 1-1/2 percent to 13

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percent was experienced due to collapse of the soil structure.' As a result of the potential for large compression of the alluvium and because of the irregular bedrock surface, large differential settlement of the dam occurred.

Sat-lement in excess of 3 feet was measured in January 1979 by a consultant to United Nuclear Corporation. As a result of differential se::lement, cracks caveloped in the embankment. Longitudinal cracks, parallel :o :he dam axis, were , observed in several locations prior to the failure. ,

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endicul ar to the dam axis and entending nearly to the cownstream srell, .

have been cbserved in the. breach area after the failure. Tnese cracts causec high pore water pressur.e to be developed within the embankment when :ailings water was allowec to come into direct contact with the embankment.

For some time period immediately prior to the failure, tailings water was maintained in direct centact with the embankment near the breach area.

Tne high pore water pressure in the embankment resultec in a cecreasa in the strength cf the embankment and caused instability to develop. After the instability was created, the large flow of' water through the cracks resulted in internal erosion which accelerated the breach. One facter which cay have hei;ed to accelerate the internal erosien is the fac that tne high teidity of the tailings water causes the embankment soil to be highly dispersive.

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hD We a e curre:~.y revf ewing ne c:erater's evaluation regarding :ne stability and ove a".1 in ag-ity cf the remaining portions of the embankment ,.

for future use. Je are i. the initial stages of this review and have no I conclusicas as yet. The :perator has proposed a staged plan to make some codificat' ens to -he imp::n: cent te allcw for resumption of milling cperations.

was during the evalua-'en of -his plan on October 12, 1979, that -he NRC

. issued an o-der : .nitec .bclear Corporttion that they canne resume operatier.s

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. ev'ew.: While we were still awaiting information from ne coert;: necs. s Ery :: review t'r eir interim p1 an, we received word initia se

y a televisier riws cas :- 3c::ser 12 1979 in Albuauercue that the State

. as seric.s'.y :cr:i: erin; a.;:ncri:'n; the resumption of cperations. Curing ne cc rse Of r.urtr:Us te:e:hene ::nversaficns with varicus officials of the 5: ate Of 'iew Maxi:: and t.e United Nuclear Corporation en that same day the NRC re:eivec var;'n_: ar.d ::-flic:ir.g rep:r.s as to whether resumption of the rill was :entempit:sc bef:re NRC =cule c:mplete its evaluation. We issued the creer to assure : a: this w:uld to: ha ppen. We are now working with -he

era :r : resol,e :.::s incing issues.

In a:d'tien : -he e.a .uatiens already noted we are going one step fur-her. F 11cwi g cur riview of aerial photographs of the mill vicinity and

n-si:e ::servati:r.s we .a.e sericus reservations about the current tailings

':p:un: cent site e .a-'ve :: len;-term sta:ility. Tne large upstrea rainff.1 r

st:hmen a en ar: _; he cl:se :roximity :: a ma,',er arroyo (stream) would seem

:r:.i:s a h';r :: ent'i> #:r surface ea er erosion Of the em:ankrsn: cver 90018190

d ne 'me peri::1necessary to :entain : e urani.m tailings. We fee". <ery s:ren;1y :ta: a comprehensive study cf alternate taild ngs sites a : disposal me:ne:s must se perfenned ex;eci:iously. If our concerns regarcir.; the  ;

i currer,t site cannot be satisfactorily resolved. we would not concur with more than li=ited use of this site wnile a new tailings site is being caveloped.

ur icng-term concerns have been ciscussed with the State anc United Nuclear Corocration managemer.: coth by letter and meetings. It is car ur.cerstanding that Ur.ited Huclear has initiatec an alternate site :_cy. We are rency to coortinate a revi' ew with :ne State of any forthecminc preposal as se:n as 't is subtitted.

sneule acc tha; arrangerents have alreacy been race for our ;ec ech-ical ar.c h;.: role;;* censultants to assess eacn of the Agreement States' .ranium tai: f r.;s impouncment systems in conjunction with our current respc..sibilities ur.cer :r.e Tai'.ings Ac:. We wil' cer ainly extend the scoce of the tailings dam assessments relative to the findincs in this case.

ke nave liso reviewed our docket files on the tailings dams 2: cperating m'l* s in non-Agreemen- States and in all but one case, differentia' settle:er.t was sa-isfac :rily accressed in cur sec echnical evaluatien. The Exception is a dam na: was authorized in 1971 anc tne documentation doesn't spEcifically

'rdicate that differer.:ial se :".ement was addressed. However, nc Ev'dence of excess've cifferential settle er.: leading to cracking has shown u; ir our I 1

rcutira inscection of this da:.

l s: sci #ically askec ,us to dis:tss the acciden: anc its reit-i:nshi: '

:gr recen:l/ :rc:csec. regula icns.

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Tne .EC has just preposed regulations which specify recuirements for

. rani.m ..ill tailings disposal . If :here is no objection, I would like :: ,

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supply for :ne record.a copy of those regulations as they appeared in the Federal Recister on August 24, 1979. These proposed rules are based on a study that ::ok several years and culminated in the Generic Environmental I . pacts Statement (GEIS) on uranium milling, issued in the spring of this yea . It is also based on our practical licensing experience of several years, during wnien :ime we carried Out a major program :f upgracing tailings

is:csal ractices in States that we regulate. Furthermore, of c:urse, the reg.laticns incorpcrate the various previsions of the Mill Tailings Ac:

c:.r.:erning insti:nicnal c:n rols, such as land ownership rec.uirements, rec;. ired f:r proper ailings cisposal.

Tne regulations identify certain siting and design features which mus:

s in:Or; ora ed into tailings disposal programs to assure long-term isolation anc con: air:nent of tailings without continuing active maintenance. More s:e:ifically, the regulations identify burial of tailings below -he surrouncing i 1

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e, ei:her in mined cut c:en pits or in specially excavatec pits, as the 1

preferrec r:ce of tailings disposal. In this way, dams such as the ene which l fai'.ed at ne Church Rock mill are avoided.

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Belew grade murial is favored primarily because of the pr:: action i- '

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r:ddes tr.e tailings dispcsal area frcm the continuing winc anc water i 4

e :si:n that will c::ur over -he thousands of years that the tailings wil:

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retain na:ar:cus. Tnis method. Of disposal also has the ::vious sice :enef't of eliminating.the potential. for +apid and large failure during :he period of n 0

active . milling operations when taere are large cuantities of tailings solutions  !

to ccatain such as occurred in the Church Rock case.  !

Tne proposed regulations recognize that belcw grade :urial say not be

.;racticable in all cases and specify certain design and siting recuirements

,hich cust be foll:wed when tailings are impcunded behin: ca s a:ove grade to assure icng erm isolation and' stability. For example, ne regulations recuire na: ailings be impounded near the head enc cf a craina;e area to elimir.a:a, er recuce as much as possible, the potential #:r wa er eresion; very ;racual eccankment slopes protectec y course rock :r stacili:ed with-vegetaticn are requirec, again, to reduce effects of winc and wa er erosion.

ae have proposed these regulations primarily with new ailings disposal c: era-i:r.s in mind. We will apply the pr: visions Of these regulations to the maxim exten practicable on operating mills. Cbviously, after many millions of Ocns Of tailings have been generated at a site, it is cre diff' cult te ike 'u .camer. a1 change in the way tailings are being dis:: sed of, such as to

ve :ailings from a location having high erosion potential to ano:he.r, more suita:le site.

n some cases, hcwever, such as acpears to be the case with :ne Church R:cx :1:1, tnis may be warranted. ' The mill has cperatec 'or only a few years i in: re: a:ively 'ew tailings have been 'mp:uncec a :he s- a. As cen iene:

et 'er, -he si e a:: ears from Our review so far o have .ery :c:r er:sion .

.:ra a::aristi: , and we-have infermed :ne opera :r :f :ne reec :: -a:Pl re

. ser':.5 j :na t .;cunc ent of tailings E a cifferen si a.

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. . In ' a.nswer then to the question of how our proposed regula:icns relate to the failure of-the Church Rock dam, the thrust of our regulatiens is clearly to avoid where possible the 'use of dams for tailings containment. *he Church i Rock. incident underscores the prudence of this goal.

I would like new to discuss our. response regarding cleanup and decontami-natien. We have established with the State a comprehensive sampling and monitoring program which will, first,. identify all areas triat have been c:ntaminatec, and second, monitor the cleanup of affectec areas. Soil and s: rem-water samples are being taken along the entire length of the potentially contaminated stream, including areas of Arizona. Tne monitaring program is

eing ::nducted by State and NRC personnel with some assistance from the cpera:cr.-

Tc previde the kind of independent radiological assessment capabilities -

recuired in this case, and to rapidly process sacoles as cleanup progresses, the h?,C has set up on-site a specially equipped mobile labora:Ory. Tnis labcrat:ry was brought to the site when it became clear that :ne State did no r. ave the capability to ' rapidly process- samples as is required to assure that the cleanup efforts will be conducted in a full and expeditious manner

-by the mill operator.

Estimates of the amount of tailings released from the failure have variec, but it appears that at least about 1.00 million gallens of acidic tailings solutions and 11 hundred tons of tailings solids escapac from the

ailf ngs impoundmen:- area before the break in :ne dam ceule be cicsed. Most cf : e solics were :e:ositec in an area very near the im: uncment in a sackup q 90018194 i 1

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entai:=en area en opera:Or property and in an adjacent stream, the s:-called "Pi peline Arrcyo." The sciutions travelled in the Pipeline Arroyo to the Rio Puer:o which ficws t.rcugh Gallup, 'iew .W.exico, a town aoout 20 c'les i southwest of the mill site, and into Arizona. By evaporation and by percolation into the stream :ottom, the spilled solutions eventually dissipated at a point estimated :y visual Observations to be about 20 miles into Arizena.

Tne Pipeline Arroyc s ream and Rio Puerco run in channels which, exce:t for- pericts of heavy rain, are very small streams. The release of ta' lings solu ic.s resultet in a flew wnich filled the entire channel,

en aminating tha normai%. cry bottcm per ions, or " terraces," as trey passec. Tne res.1: as ' .cicatec by cur measurements was a widespread i contacinatien of t::e :er a:Es we::ed by the released solutions. The c:ntamin-  !

i ation levels appea:- to'te uniformly above natural soil concentratior.s of

-horit.:n-220 radta: tivi:y. There are isolated areas on the terraces v.ere l

contamina icn is cuite c:r.:entrated, being as high as 100 to 500 ti es j aackgrotnc levels. Tnese are, 'n many cases, areas where solutions oe:ame strancec in iso'.atec pocis after the spilled solutions passec. Tne .cnitoring effer: has been aimed at identifying these areas of concentrated cor a;nination and the cleanup effer: nas consisted of removing these concentrates.

Let ce summarize, than, in general ter:as what the potential health )

I impacts of this incident have been and are. The most immediate nazar: l t

resultirg free tne inci:ern related to the drinking of or having sk'.n contact ahh the ailir.;s sclut':.- whics. is highly acidic. This c:ndition ex'sted at 90018195 i

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Chure. :ock Lfor or.*y a snc : peric: of ; ire, ;rchaoly a day or we, until the wa ar-f :: upstrea: mining ::erati:ns anc -te natural alkalinity of the strea bed neutralized thi :ailin;s solution. The radicactivity in the tailings p

' is no: of.a nature to be an innediate health risk.. Certainly, however, if c:ncer.trations a:f the tailings are left i :he arroyo they woulc constitute a health na:ard :: t.e local public ever the long run.

7De we so.'rCis of pc ential Lblic axposures to raCicactivity in 1

nis :ase are c:n unina ac sci.ls anc water.

e have ad.isse the 5: ate cf sha wo*.lc ce a:ceptable cleanup levels of :ht :or aminate: er-aca soils. Varic.s : ter.:ial ex;osure ;aths which affec- .u an heal- -ere eis:catec wi-h ras:ect :: -he levels of radicactive

nta-i a-f c. t..a: wcule a;is: in -he arr:ye fell: wing cleanup. Specifically, se le:ked at the f:1 cw'ng pctentiai pathways of exposure from contaminated s:il : 'nrai ati:n :f racct, :irec gamma ex;csure, direc inhalation cf

nta..i .a ed wi.-db'cwr. :ar-iculates, and ingestien of water or foods contamina:&:

ay witc:lewn parti:ul ates :r leactsc activi y. P :ential exposure frem these

a rways 'silcw'ns clear.u; w'll be small fractions of es aclished radiation I ex:cs:rs limits of :ne Com:ission (10 CFR 20) anc the Environmental Protection Agency .40 CFR ". 9C . We are recoc:ending a cleanup to a very icw level of resi::a* :sil E:nta:'na:ic 'n kee:ing wi-h -he basic philesephy that exposures i

any acioac 'vi y shcui: :e rec cee :: ne maximum ex:en: reasonably '

acnievarle.

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' The o;ner irect an; catr.way of concern involves human censumption of lives:ccx anc animais which crink water from the affected stream or from nearcy well s. h is our ur.derstanding that there is no direc: human consumption  :

L cf stream water in the areas that hate been c:ntaminated.

From limited data available on racioactivity in surface stream water, it i appears -hat thori:.m:-220 in the strea;n is remaining at elevated levels. The i

stream water is ap;arently picking c; and transportinc thorium that was  !

i cec:sitec in -he stream becs at the time of the incident. .Nothwithstandi ng l

nis, ex:ssures to fr.:ivii.als eating livestock which crink frem the stream a: Observec levels wi'l be fractions of EPA and NRC ex:osure limits. It is r:re difficui Ic assass tr.e ;otential for exposure through use of wells near  ;

ne affec e-d streat. We cc r.:t as of yet have firm data to deter;aine the exten; tc which cor.centrated tailings solutions haved percolated into groundwater.

Rac'cactivity tha may be ; resent will tend to be recoved in the subsoils by a r.z ural acsorpti:n :rocess anc be ciluted by greurcwater. Ncnethel ess ,

just as witn surface water centamina-icn, this is matter which must be wa::ned by centinued monitcring by the operater, Sta e and NRC.

Following cca:ie: ion cf :leanup, the NRC, possioly jointly with the State, will issue a report. he reper: will document satisfactory completion cf the cleanup, will :e a full statemen of the environmental impacts that j have Occurrec, ar.d si'.1 reextend wha: onceing moni ring should take : lace to c:r. firm tha: :here will no :e a later problems such as contamination of' wells i near ne stream fr:m seepace 'nto cr:unewa:er.

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I migh; note ua: we i. ave made a special effort to respond to the

ncerns of the : ecole living near the affected stream, particularly the  :

1 Navajo. The NRC staff has me personally with representatives of the Navajo Nation to review with them our efforts. As a result of that meeting, memcers of the Navaje Environ. ental Protection Commission are participating ,

in the cleanup m:nitorin; pre; ram witn NRC and State personnel. We believe

-e have a::an::ec .: :ne :e:ific health concerns that have been raised, i cluding samplin; areas al r.; the stream tha: :ne Navajo have pointed cut as tiing use: fcr s::c < watar' ng.

0:ncaming cur relati:nsr.ip with EPA in nis mat er, we are in frequent c:n act witn the EF A excharging data anc techr.ical assessmen s we have conducted.

We have kep: EPA abreast of our actions as far as setting cleanup levels and c:nitoring clean.: :; era:icns are concerned. We will be censulting wi-h them f:r= ally as we write our final report on the incident and cleanup operation.

In s= nary, :he imme:1ata health hazard resultir.; from -he f ailure was the freestancir; tailirgs solutiens that existed for a cay er two before

ne solu-icns wer e :ilutat. Tne tailings the selves are not Of a nature to be an imrediate health risk but if left in the arroyo would constite:e a health ha:ard t: the local ' public over the long term. Analysis so far

'ndicates .at ra:i: activity in strea:: water is appreciably acove background levels bu: belcw limits s:ecified in cur regulations. Continued cicsa menitoring

1. strear wa:er a .c wells '-il' be reocired. 'RC has :een working wi n and

.fl", c:ntin.e :: a:rk wi . the Stata regarcin; clean-ep cpera:icns and

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ecr.ni:a*. ana*jris Of tre site. A I have stated, tne -hrus: of :ur

-::: set re;ul1:':rt is :learly to av:id whers ; ssible the ;se of des for 90018I98 L_

b tai'. i .;5 c:ntai ncar.:. The Church Rock incident anderscores the ;r dence of this ;oal. This scl;; ion is =cre readily adapted for new sites versus exist'n; ones. -

would like tc emphasize that this testin:ny was prepared as I-a res.1: of car analysis and evaluation of the data to this date ar.d our testi:ony may be affected by further analysis and evaluation of th.e data to be perferned in tne r.ex; few acnths. We would welcome the opportunity to testify a: any future hearinc en this suoject and/or provi:a you mere current

'rf:rnati:n sne_ld ye; re;.f re it.

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