ML19295F713
| ML19295F713 | |
| Person / Time | |
|---|---|
| Issue date: | 10/31/1980 |
| From: | NRC OFFICE OF STANDARDS DEVELOPMENT |
| To: | |
| Shared Package | |
| ML19295F714 | List: |
| References | |
| TASK-OS, TASK-SC-722-4 REGGD-03.011.01, REGGD-3.011.01, NUDOCS 8012170049 | |
| Download: ML19295F713 (8) | |
Text
9 0 3~
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U.S. NUCLEAR REGULATORY COMMISSION a
(4M REG!JLATORY GUIDE A
%..'... J' OFFICE OF STANDARDS DEVELOPMENT REGULATORY GUlOE 3.11.1 O?ERATIONAL INSPECTION AND SURVEILLANCE OF EMBANKMENT RETENTION SYSTEMS FOR URANIUM MILL TAILINGS A. INTRODUCTION tailings are usually stored behind man-made retaming structures, following the p.actice of the non-uranium Fach licensee who processes or refines uranium cres in a mining industry. Unlike most r on-uranium mine radings, a
mi] ling operation is required by $ 20,1 of 10 CFR Part 20, uranium mill taings contam concentrations of radioactive "Standa;ds fer Protection Against Radiation," to make materialsin excess of the allowable discharge limits (Ref.1).
every reasonable effort to maintain radiation exposures and Furthermore, the most significant radioactive element in releases of radioactise materia's in effluents to unrestricted the tailings is radium-226, which has a half-life ' about areas as low as is reasonably achievable, taking into accCunt 1600 years (Ref. 2). Therefore, it is necessary to confine the state of technclogy and the economics Cf improvements those tailings to prevent or control their release to the in relation to benefits to the pubik health and safety. In en"tronment not only dunng the operating life of the mill addition, 40 CFR Part 190, "Ensironmental Radiation but also for generations af ter milling operation has ceasc1 Standards for Nue! ear Pner Operations," requires that the The embankment, foundation, and abutments need to be maumam annual radution Jose to individual members of stable to prevent the uncontroUed release of the retained the public resulting from fuel cycle operations be liraited to water or semifluid taibngs. Seepage from the taing pond, 25 millirems to the whcle body and to all organs except the which contams dissolved radium and other toxic substances thyrcid, which must be limited to 75 millireas. Liquid and (Ref. :), needs to be controlled under normal and severe solid wastes (tadings) generated in the uranium millin; operating conditions to prevent the possibthty of unaccept '
operation contain radioactive materials in excess of the able contamination of the youndwater er nearby streams, disctur;c limits and are generally confined by au cmm..,
sind and water erosion of the tailings needs to be presented ment retentien system.
during and af ter the mi!!ing Cperation.
Regulatory Guide 3.11, " Design, Construction, and Therefore, the design and construction of these facihties inspection of Embankment Retention Systems for Uranium require a high 'cgree of professional engineenng performance.
Ells," desenbes a general basis forinspection of an embank-The foundation of the dam should be stable and should be ment retention system. This guide, a supplement to Regula-capable of carrying the weight of the structure. The dan.
tory Guide 3.11, descrites in geater detad a basis accept-should be safe under the application of external forces such able to the N RC staff for developing an appropnate inservice as those resulting from earthquakes. The reservoir area inspection and surveillance program for carth and rock fill should be water retentive md free of the possibthties of embankme..;s used to retain uranium mill tailings. It results dangerous slides. Dams and associated factlitie should be from review and actiCn en a number of specific cases and maintained in good working condition throughout thir reflects the latest general approaches to the problem.
operating lives. Operation and surveillance through the The NRC staff will review any alternative mehods to years should be conducted in such a manner that any determine their acceptabinty.
changes in their d:uctural, hydraulic, and foundation conditions can be detected promptly and corrections made.
B. DISCUSSION Statistics of water retention dam failures, based on the The milling of uranium ores results in the production of sum of operation years of a regional group of c.,sms (Ref.3),
large volumes of liquid and solid wastes (tailingst These show a frequency of one failure every 1500 to 1800 dam-years. Statistics of uranium mill tailing retention dam failures show a frequency of one failure every 40 dam-years Lines indicate substandve changes frorn preuous tssue.
( Ref. 4h USNRC REGULATORY GU1CES Comments should ce sent to the Secretary of the Commission, U.S.
Nactear R egulatory C om mission..vasnington, D.C. 205 55 Regulatcry Guices are isssa to oescrete and ma,e avairatie to the Attention: Doc =eting and Service eranen.
ouche metnoas to the NRC staf f of sm olemen tin 4 soecific carts of accep t a o,.e tne cor rnission s regulations, to den.neate tec%
Tne guides are issued in the following tsn ercad divisions:
nmues used ov ine staf f in evab.ating specific prootems or costu-lated accicents. or to provice picance to acchcants. Regulatory
- 1. Do*er Reactors
- 6. Products Guices are not substitutes f or regurations, and comoliance aitn
- 2. Research and Test Reactors
- 7. Transoortation them is not reau red. vernocs anc sosutions cifferent from those set
- a. Fuels anJ Materials Facilities
- 3. Occupational Healtn
./ cut in tne guices,wm ce accectanie if they crovice a casas for tae 4 Environmental and Siting
- 9. Antitrust and Financsal Aev;ew findings recurs.te to the issuance or cer tinuance of a permit or
- 5. wateriass and plant Protection 10. General license or tne Commission.
Cooies of issued 3 edes may be purcfiased at tne current Government Comments and suggestices fer imorovements in these guaces are C
ting Of fice price. A sacscriatica service for f uture guides in see-encouraged at ait times. and quices will ne revised, as acorocriate, civisions is availacie tnrougn tne Government Nicing office.
<.t to accommodate comments and to renect new in f ormation or
. mation on the suescriction service and current GPO or.ces may einerience. This guide was reviseo as a result of suestantive com-cs brained oy writing tne U.S. Nuclear Regulatory C cmmission, meets received from tee puDlic aad aGCitsonal stJf f review.
W a shin gt Cn, O.C. 2os s s, Atte9tions PuDliCations Sales Manager.
} l k
Causes of latent danger inherent in such works anse needs to be examined for any conJiticas that ma) impese from site cond,tions, hydtclogic and hydraulic features, constraints on its operatten.
types and quahties of the structures, operation and main-tenance and influence ef the enstronment (Refs. 3, 5,6, The operation of t?. slurry transport pire3nes seems to and 7L Of these causes, the ma;cnty he within the bcundanes be relati,ely s:mple, but the frequent ruptures of H of modern technclogy and can te avoided. Most failures pipelines i Ref.10) inteate that close mnnitoring needs to hate resulted from gradually worsening defects f due to be performed unng operation. ' certain degree of segega-design, cons.uetion, operation, or lack of maintenance) tion occurs, with the coarse sand fraction of the radings that were either undiscovered or misjudgei Table 1 lists the tending to settle at the bottom portion of the pire. On reported tiding acGdents frorn 1959 through 1979 relatively steep downslopes, the coarse sand fraction cascades down and, in the process, abrades the pipe wall.
The design and construction cf t. ding retentien structures When air is entramed m the pipeline, the pulp velocity have, m 'he past, been based largely on mining expenence, increases as a r,sult of the reduced cross-sectional area of with httle use of design concepts. These empiricalapproaches the pulp flow and results in relatively f ast wear on the pipe wa'. Regular pipe-wall-thickness determmations wdl enable d
have resulted in vancus mmmg dam misaps and fadures t Refs. 8 2nd H. The latest advan:csin geotechnical engineer-various remedial measures to be adopted to a!!eviate the ing, together with engineermg expeneace and know! edge situation. To help protect against the consequences of avadaMe in the fie'd of water storage da ns, can be used in s!urry ruptures at :ntical locations, the new can be caught the design and constni.nen of tailing retention dams.
and safely directed by an adequate troug4hke device (e g.,
!!uweser, the retention sy stems may net always perform as a launder). Safety can be further ensured by detecting expected, construction may be defectne, and founJations ruptures immediately sa measures can be taken quickly.
may need further treatment af ter a pened of operation. To Currently, it is nctice to use alarm-triggering flow rate detect su:h benas ier deviations. regular survedlance is senscr! installed at nozzle outlets to detect ru p tures.
essential.
cloggings, er other slurry Cow irregulanties.
The weakering of a dam or its foundation may become Inspection personnel need to be carefully telected. It is mparent only after many years of safe operation. Painstaking important that they be practxal, dedicated diagnosticians ocnitoring and analysis of rerformance data are necessary who examme thoroughly every ch:e du ing their scrutiny of behaver of these facdities. lney need *.o be trained to to ensare detection of adverse ;onditions. Each structure.
as w eil as each site, has its own :haractenstics and its be able to recognize ana assess egns at possible distress own suscep tibdities to problems, and the survedlance or abnermality and to recommend appropriate rnitigating program should be f adored to accoant for these.
measures.
Therough physical examination is an esser si part u C. REGULATORY POSITION the survedlance program. The optimal frequer ey of inseec-tions depends on the size and condition of the bedit:es, the This guide applies to those systems or portions of character of the foundation the regional geo! gi:al settin:,
systems whose failure could cause releases of radioactise and the consW mees cf fadare in jeopar.izing human efnuents in excess of the limits pnen in 10 CFR Part 20.
hfe and :nfhetir+ coperty damage.
Inservice inspection and surveillance should te performed at regular intervals to check the condition of the retention Before the start of tailing disposal. it is mportant that systems and associated facuities and to evaluate th -
reccrds of t :zometer levels tincluding seascr i! Suetuatiens, structural safety and operational adequa;y. A detaded, gromdwu gaality, ground elevations, L d background systernatic inspection and su vedlance program should radioaan":es at the site) be compded so t!.at ;omp.. ison consis of, but not necessarily be limited tc. the following can be made with the effects of the impc inJment. Data gatnered in accordance with Regulato y Guide 4.14,
- 1. Engineering Data Compilation
" Radio! wal EffLnt and Environmenta! Monitcnng at l'ranium Mdis." wi'l provide useful informelon for deter-Engmeermg data' related to the design, construction, mining the integrity of tadings dams. As scoq as the rading and operation of the tailing retention systems shculd be disposal begins. the inspection and main.! nance program collected and, to the extent practicable, included in the for structures and operating equisnent neer sto be initiated.
mitial inspe: tion report. These data should.n lude the This program includes regular patrol of.he dam and its following itens, where available and appropriate.
abutments, observations and estimates ; seepage flows, piezometne levels related to pond leve.i. structural and
- 3. General Project Data foundation m ove m en t s, sam phng of oundwater, an d c u min ation of slurry transport and.ecant pipelines.
f1) Regional vicinity map showing the project Attrntion alsa needs to Se focused on inspection and data location and the upstream and downstream drainage areas.
cclie: tion dunn g relatnely rapid changes m reservoir
'% encineern data f as presented in accor3ance mth Recula-water surface elevations. The emergency discharge facthty tory Guide 3.11 and Secdon Ls.6 of Regulatory Guide 1.70,"StanJ-4 {or jisposing oj r,codwater runoff in excess Of designed ard Format and Cortent or Safety Ar dysis Reports for Nuclear o
Powr Plants") are readilv avadable m Jocuments filed f or a mdl pond capacity) rnay consist of disersion channels, spdlways.
heense applicathn. A Jetaued reference or the original documents Mverts, or other desi;zns. To ensure proper operation, it kept at the project site shouia he adequate.
3.11.1-2
(2) As-built drawmgs and photographs of important
- a. Dady inspection project features, including details of decant systems and n pical installat2cn of mstrumentation (e.g., sectional v:ews
(!) Decant systems should be examined for any and matenal zoning and.' nundation stratificar:on, fmal top esidence of cle ting of the intake; corrosion, cracking, er and bottom elesation, gradation and properties of matenals crushm! of decant pipes;and crosion at the discharge pomt.
placed in installatton).
The character and quantity of water Dowmg into the inlet and Gowing out of the discharge should be compared for evidence of cracks or open jomts.
- b. Hydrologic and !!ydraulie Data (2) Efnuent from underdrain pipes should be exam-(1) Drainage area and basin characteristics.
ined for evidence of clogging, cracking, and erosion.
(2) Storage for tailings anct surcharge capacities for (3) Pcnd water elevations should be examined md Goods and rate of slurry inflow.
recorded to correlate them with piezometer levels and to ensure that mmimum freeboard is maintained.
(3) Elevation of the mnimam design pool and freeboard height.
(4) The slurry transport sy stem should be exammed for any evidence of obstruction of the pipes or pumps due 4 4) Outlet fac:hty charactenstics Gocation, type, to sand clogging er ice accumulat:en. The pipe couplmgs dimensions, and elevation).
should be examined for leakage of slurry, any Cowrate sensor should be tested, and any launder examined to
- c. FounJation data and geological features, including ensure proper operation, bonng logs, pological maps profiles, and cross sections.
(5) The retention dam should be visually inspected
- d. Properties of embankment and foundation materials, for signs of cracking, slumpmg, movement, or ccncend stion meludmg results of laboratory tests and field tests. and of seepage.
assumed design matenal prcperties.
- b. Monthly inspection
- e. Pet:u-t construct.on photographs and records, incluaing constructinn control tests, dewa!enng method a') Slurry transport pipes should be examined using and constructicn problems, alterations, modifications, and an ultrasonic device at locations where pipes cross streams mamtenare repairs.
or other natural water courses or where a rupture of the pipe could be expected to affect the stabihty of the embankment.
- f. Contmgen plan, including a plan for the regulation of pond water elevation under normal conditions and (2) Diversion channels should be examined for dunng Good events or other emergency conditions.
channel bank erosion, bed aggradation or degradation and siltation, obstruction to now, undesirable vegetation, or
- g. Pnncipal design assumptions and analyses, incluCng any unusual or madequate operational behavior.
hy drologic and hydraulic analyses, stability and stress a.ulyses, and seepage and settlement analyses.
- c. Quarterly inspection
- h. Special license conditions and discussion on how (1) Embarikment Settlement. The top olthe embank-these conditions have been met.
ment and downstream toe areas should be examined and surveyed for any evidence of unusual totalized or overall settlement or depressions.
- 2. Onsite inspection Jrogram
(;) Embank.*xent S,' ope Conditions. Embar.kment slopes The onsite Inspection program of the retention systc~1 thould be examined and surveyed forirregulanties in align-should be estsbbshed and conducted in a systematic manner ment and variance from originally constmeted slopes, unusual to minimize the poss:bdity of overlooking any significant changes frorn onginal crest alignment and elevation, evidence features. A detailed checklist should be developed and of novement at or beyond the toe, crosions, and surface followed to document the observations of each significant cr.co that indicate movement, geotechnical, structural, and hydraulic feature, including electncal and mechanica' antrol equipment.
(3) Scepage. The downstream face of abutments, em-bankment slopes and toes, embankment-structure contacts, The use of photographs for comprrison of previous and and the downstream val!cy areas should be examined for present conStions should be included as a part of the evidence of existing or past seepage, springs, and wet or mspection program.
boggy areas.
The inspection should include appropriate features and (4) Slope Protection. The slope protection should be items,incluJtng, but not hmited to, the follodng exarnined for erosion-formed gullies and wave-formed notches 3.11.1-3
and hen ches. The adequae i et store protectwn agamst waves
- 3. Technical Esaluation and surf a
- runetf ; hat may occur at the site snould be eva:uate d. I..e condition ci segetation or any other ty res
\\n na au n the cum anainons of :M retention of prctestae mosers shN!J he evaluated 4 hen rtrtment.
sy stem should be made annually unless changng anJtt: ens
- '" ' " ' * ' I' " # ' " " ' "**
'#U '"
assessment of the hs drauhc and hy dr< ome uracines 5 'ater t i p Emergency Ducharte T:cWty The emer:en;y w
docharge faedit) exammation s!.euld over the st ue:ures and quahty. and stru;tural stah!!!) and snould take mto account teatures, including spillw ay bulkheads. cuherts, retammg a
both emtmg,onj.tions and ans thanang conditions. In wa's, and wing walls ct disers:on channels, for any cend.tmn addition, surface sater and grourdwater s mphng data that nuy impose operational constraints on thetr f unetiening.
collected m acecrdance mth Regulatory Guide 4.14 should be exJmmed at the ' 'ne of the techNCalCValu3 tion to deteCI (s) Safety :nj l'erform:nce hs trum er:tanan. 2 NJ any patterns that could be a sign at. failure of seerage con f installe d instrumentation such as flow-monitoring weirs.
trol measures or,oundation distress.
I survey monuments, settlement plates or Fa8es. and Ple20-meters should be exarnmel and testeJ for proper function-mg. The asaJable records and readmgs of these m>truments should be reviewed to detect any unusual perfermance or
- 4. Inspection Report distress of the structure.
.\\ report should be prepared to pre ent the results ut t D Operation and 3famtenance Features. The main-each te# meal eva!aatien 2nd tN :nsrecuen data accumulated renance of operating faclit:es and features t su;h as rumrs sece "c last repert. These Jccuments shou!J he kept at and vahess that pertam to the safety of the retention system the pro;ect site for reference purposes, should be asailaNe should be exammed to Jeterrame the adequacy and quaW Mr msrect:on by regulatory aathorit;es. and shculJ he of the rnamtenance procedures toi! owed m mamta:r.4 :he retired only on termmation of the project. \\n> 2Fnormal dam and facilities in safe creratmg condition.
hazardous conditions cbsersed darmg the mirection incu!d be reported immediately to the NRC statf.
( 8) (Ustcons:ruct:an Ch:nges. Data should & cr>llected on changes rich as land devel rment or large-scale tree cuttmg m the watershed a ea abose the fa;thty that h.ne
- 5. In3pection Personnel occurred smce prcJe:t construction and that might inCuence the safety of the project.
Inspections and evaluations should be planned and conducted under the direction of an e trenenced professmnal
- d. Special Inspection who is thorough!y famihar with the investtption. design.
con"rucuen. and ope:at:on of these types of f acihties. \\t Unscheduled insrect;ons shcu!d he performed atter each facdity. this individua! shou'd ensure that a:1 field the occurrence of sanifica -t earth,p skes, ternadoes. Goods.
msrectors ire tra:ned to be able tc recernue an ! 2vess miense local ramfa:Is. or ot ter unusual events.
signs at posstNe d;s ' as or abnormalay.
I m m e di '
- el) f niemng inst allatien or the hs6uvery of.n unum) conJitior. M marrumentatson neeJs invre fresiuent realme.s than y
auarterly (e4.. Juh or weeki)) until the ratterns vf the structural tf ajJittonal storage caraat) as nee Je j. N HC sbuld he notif"e j behavion are stahlared.
a year m advaxe.
3.11.1-4
REFERENCES 1.
S.R. Scrro4 man ar.d P.T. Bruoks, " Radium Remoul 6.
A.O. Babb and T.W..\\lermel," Catalog of Dam Disasters, from Uramum Ores and \\li!! Tadings," Bureau of Fadures, and Accidents," Bureau of Reclimatien, U.S.
\\ tines. U.S. Department of Interer,1975.
Department of Intenor.1963.
7.
" Lessons from Dam Incidents, USA," ASCElUSCOLD 2.
"Use of Uranium %!!!! Tailings for Constructon Pur-report,1973.
poses." Hearings Before the Sabccmmittee on Raw 4/aterials of the Joint Committee on.-tromic Energy 8.
R. Dobrey and L Alvarez," Seismic Fadures of Chdean of the U.S. Congress,0ctober 28 and 29,197i Tadings Dams," ASCE Journal of the Soil.t/echanics and FounJations Div., November 1967 3.
E. Gruner, " Classification of Risk," haceedings of 9
W. A. Wahler and D P., chlick, "5f am Refuse Impound-international Congress on Large Dams, \\tadnd,1973, ments in the U.S., ' Proceedings of the Inte rr:ationa!
- ol.1,."p. 5 5-6 8.
Congress art /pge Dams, Stetico City,1976, 4
"Su m mary of Tading S!urry R elea se-1972-19 77,"
- 10. R.C. Salazar and R.I. Gonzales, "Deugn, Construction, report prepared by Teinekron, \\f arch 1978.
and Operation of the Tailing P:pelines and Underwater Tailing Disposal System of Atlas Cor:solidated.\\ fining 5
E.S. Smit 5. "Tading Daposal-Fadures and Lessons "
and Development Correration in the Philippines," ho-Proceedmis of the First hternanonal Tat:ing Sym-credings of the First Internat' mal Tauing Symposium, resium, Tucscn, Anzona, November 1972.
Tucson, Arizona, November 1472.
BIBLIOGRAPHY
" Recommended Guidelines for Safety Inspection of Dams,"
National Dam Safety Act, Public Law 92-3t>7,86 Stat. 506 Federal Reguter, Vol. 39, No.168, August 28, 1974, and 507, August 3,1972.
pp. 313 34-31346.
"Penodic inspection and Cmttnutng Evaluation of Cornpleted "Engineeug and Design \\t an ua!--Coa; Refuse Disposal Civil Works Structures," EM 1110-2-100, Corps of Engineers, Facilities," U.S. Department of Interior, \\lESA. Prepared Department of the Army,1973.
by D'Appolenia Consultmg Ergineers, Inc.
"%fodel Law for State Supervision of Safety cf Dams and Reservoirs," U.S. Committee on Large Dams,1969.
" Guidance for Planning of Inspection Progams fcr Dams,"
USAEC Technical Guide I.II.!, November 1971.
" Statutes a.1 Regulations Pertaining te Supervision of Dams and Reservoirs," Denartment of Water Resources,
" Inspection, Staintenance, and Rehabilitation of Old State of California,1974 Dams," ASCE,1974.
D"*D d
"D'3'} b Jl 3.11.1 5
TABLE 1 UR ANIUM MILL TAILINGS RELEASES 1959 1979 DATE MIL!. AND LOCATION TYPE OF INCIDENT REMARKS S!!9/59 Union Carbide T4 g Dike Fauure Taihngs dam washed out..15 000 T sands lost to Bro *ns Wash and Green Green Raer, UT River in flash Good; no increase in dissolvi Ra was noted m river.
9/? L60 Kerr McGee Raffinate Pend 240.000 g.d of raffinate released mta Shiproc k, NM Diie Fadure San Juan River; s 50 t 10 Ci.ml Ra-226; met samples cc!!:cted seseral days after release sho*ed no increase in Ra ' 6 background. mer at Medi;me Hat (100 mi downstream of plant) showed 0.3 6 t 10* Si,ml Ra :26 on s/30 60.
12 c.61 Unien CarbiJe Tadtng Dtke Fadure 500 T solids released frem ruhrgs area; 200 T reached unrestricted area:
May bell, CO no liquid reached any ficwing stream.
These tailings toffsite) did not constitute a hazard as no persons hved in the area and no dnnking water was taken frem surface or groundwater in the near viemity.
o!!1,62 Mmes Develcpment, Inc.
Tailing Dike Failure 200 T solids washed mto Cottonwood Creek and some carned 25 miinto Edgemont. SD Angostura Reservoir.
sil? 6:
Atlas-Zine Minerals Slurry Pipeline Est. 250 T solids + 240 T Iquids released Mexican Hat. UT Rupture from broken tnhngs discharge line ato draw 1.5 mi from San Juan River. Caku-lated concentration of river water would have been below 10 CFR Part 20 mnimum permissible concentration.
6'16s63 Utah Construction Tading Dike Material released by -ft drainage cut made R2verton, WY Precautionary to prevent cresting dut to heny rains; Release matenal released below 10 CFR Part 20 values.
11;'17,66 VCA Raffinate Line Est.16.000 gal of liquid !ost because of Shiproc k, N M Fadure break in raffinate line; matenal spread over
!!4 acre; break occurred I mifrom San Juan River with some small amount reaching nyer.
2/6 67 Atlas Corp.
Auuhary Decant Overflow from main tadings pond over-Mcab,UT Line Fadure flowed aus. decans system; a40.000 gal lost; average Ra-226 concentration was 5.5 x 10~8 Siiml.
7/2,67 Climit Uranium Tading Dtke Fadute Dike fadure cf unapproved retention system released 110 acre-ft of waste liquid into Grand Junct:on, CO Colorado River;noindication that R2 cone in nyer exceeded 10 CFR Part 20 limits.
3.11,1-6
TABLE 1 (Continued)
URANIUM MILL TAILINGS RELEASES 1959-1979 DATE MILL AND LOCATION TYPE OF INCIDENT REMARKS 11/ 3/68 Atlas Corp.
Slurry Pipeline 35,000 gal of tailing slurry lost; effluent Mcab, UT Rupture flowed down drywash and hen 1/2 mile to Colorado River; riverGow sufficient to give 10,000:I dilution; most solids settled out in drywash; measurement of river down-stream of plant immediately after release and at 4-hr intervals in 24 hr fouowing release showed U, Ra-226, Th-230 below 10 CFR Part 20 limits.
2/16/71 Petrotomics Secondary Tailing 2,000 gal of liquid lost to unrestricted Shirley Basin, WY Dike Failure area; break in dike of efnuent sump, spill frozen in place.
3/23/71 Western Nuclear Taihng L;ne-Dike Break on sand tails slurry line caused a dike Jeffrey City, WY Failure faJure allowing sand tars to flow for 2 hr into natural basin adjaunt to tailings site on licensee's property: fence extended to maks this area restrict-d.
2/5/77 United Nuclear-Slurry Pipeline Taihngs slur y pipehne ruptured by high llomestake Partners Rupture pressure buddup in a frozen line. The Grants, NM slurry rel cased eroded a "V" cut in the dam face, which led to the escape of approxi-mately 50.000 tons of solids and slimes and somewhere between 2 million and 8 million gal of liquid. All material reles:,ed was confined to company property.
4/77 Weste.n Nuclear, Inc.
Fadure of Tading Tailings slurry overtopped the embankment Jeffrey City, WY Pond Embankment because of insufficient freeboard space, considerably less slope than the requisite 3 horicontal to I vertical, and a loss in struc-tusal integrity caused by the melting of snow interspersed with the fill used to construct the embankment. % 2 milbon gal 3
of liquid tailings (55 yd of solids) were released. The grind mill and mill yard were completely covered, but no material was released to unrestricted areas.
9/06/77 United Nuelear Releast from In the process of flushing tailings lines, it 9/27/77 Church Rock, NM Tailings S;urry Line was discovered that a 2-inch water line had insufficient pressure to flush out plug. The line was uncoupled and roughly 1/4 ton of tails ran out of the lire. With the line still uncoupled, flushing was inadvertently initiated again, resulting in the releaw of 4,000 gal of flush water and an additional ton of tailings. Approximately 1 ton of solids and slurries and 900 gal of liquid entered the watercourse. The liquid flowing
.s to the watercourse was almost entirely mine water, a portion of whn had not been treated (i.e., high in urerb and radium values).
3.11.1-7
TABLE 1 (Continued 1 URANIUM MILL TAILINGS RELE ASES 1959-1979 DATE
%IILL AND LOCATION TYPE OF INCIDENT R E SI A R KS 7/1609 L'nited Nuclear Tailing Dike The radings embankment fadure was a Church Rock. N51 Fadure result of internal erosion of the embank-ment caused by a combination of two factors. Differential settlernent cecurred in the foundation materials anderlym; the embankment and resulted in cracking of the embankment. In additien, tailings liquid was allowed to come into direc; contact with the emt'ankment near the area eventually breached. The flow of hquid through the cracks resulted in the internal erosion of the embankment and the esentual breach. The breach resulted in the rekase of approximate!y 100,000.000 gallons of tadings solution and 1.100 tens of tadings sclids. Though most of the solids were deposited near the impoundment, much of the solution reached the Rio Puereo. Cleanup actions were undertaken and use of the river water for hvestock watering was restricted pendmg reduction of contaminant :evels.
The river water is not used for human consu m ption.
UNITED ST ATES F
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