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MemorandwnTO : Piles DATE:TIEUs Danald A. Nuss , Olief DEC I21%4

Source ect Nuclear Materials Branch, DEFROM : Don F. Harmon

Source and Special Nuclehr Materials Branch, DE

$UBJEct: AUTHORIZATION TO DISQIARGE LIQUID EFFLUPXfS I!ff0 UIEESTRICIT0 AREAS,PETROTO4ICS 004PAlft. DOCKER NO. M-6659

DEIDW

The subject company began uranium milling operations in early 1962. Priorto operations, an engineering evaluation was made of the underlying strataof the proposed tailings disposal area to ascertain the adequacy of thesite for tailings disposal. This evaluation indicated that seepage wasunlikely because of an underlying layer of impervious bentonite shale. How-ever, survey provisions were provided in the event that seepa6e did occur.Several months after operations began, secpage was observed below the tail-ings disposal site and sempling was started. For approximately a year theconcentrations of radium-226, thorium-230 and natural uranium in the soepagewere close to background for the area. However, sampling eventually detectedthorium-230 concentrations in the soepage stream of approximately 2 - 3 timesthe 10 CFR 20 limit averJged over a one year period. Accordingly, the subjectlicensee has requested an exemption under Section 20.106 of 10 Cm 20, to dis-charge liquid effluents into unrestricted areas.

The requirements for approval of an affluent authorization under Section 20.106of Part 20 are that the applicant has made a reasonable effort to minimite theradioactivity contained in effluents to unrestricted areas end that it isunlikely that radioactive material discharged in the effluent would result inthe exposure of an individual to concentrations of radioactive material exceed-ing the limits in Part 20. In this respect an applicant must provide informa-tion concerning effluent flow rates, effluent concentrations of radioactivei

materials,/or related to the discharge, anticipated concentrations of radio-chemical and physical properties of the effluent, water uses asso-ciated andactive materials at points of water uses, background concentrations, environ-ment monitoring and associated equipment, and vaste treatment provisions, etc.

As noted above, the seepage results from apparent faults in the underlyingstrata of the vaste disposal area and is not a planned or deliberate discharge. |The physical and chemical properties of the seepage are essentially the sameas those of vaste liquida from any other acid leach-solvent extraction uraniummilling process except that our experience indicates the suspended solid con-tent of seepage is usually of no concern. The flow rate of tho seepage variesbetween 25 and 30 gallons per minute (spm) except during 30 to 60 days in the

|spring when the flov is supplemented and diluted by spring run-off. At flov |rates of 35 gpm the seepage stream disappears by absorption into the groundwithin one-half mile of tha restricted area.'

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The subject mill is located in the center of the Chirley Busin approximately32 air miles south of Casper, Wyoming. The area is semi-arid, devoid of treesand has very little surface water other than spring run-off from melting snow.There is no cultivated ground within 20 miles of the plant and the nearestinhabitod area is a uranium mjning camp of some 200 people located 5 miles fromthe plant site. The nearest permanent settlement to the plant is Medicine Daw,Wyoming, sone 30 air miles south. The only stream in the crea is the LittleMedicine Dav River which is located over 5 miles down dry gullies from the millsite. The licensee reports that this river has a average now rate of some9 million canons per day. There are no known withdrawals of water from thisriver for either culinary or irrigation purposes between the mill and the townof Medicine Bov.

If one assumes that all of the effluent (35 gpm at 2 - 3 times the Part 20limit) reaches the Little Medicine Dov River, there vould be a dilution factorof approximately 1,000 at the average daily flow rate of the river as reportedby the licensee. Background and downstream samples obtained by the licenseoindicate no detectable increases in concentrations of radioactivity in the river,

! as expected, since the etnuent only reaches the river during a 60 - 90 dayperiod vben additional dilution is available. Therefore, there does not appearto be much probability of water sources, at points of uses, being effected to adegrw that increases in radioactivity would be detectable.

The licensee, in an effort to reduce seepage and concentrationsof thorium inthe seepage, has instituted a two fold program. To reduce seepage, the licenseeplans to continue his prccedure for depositing tailings within his tailingssystem in such a manner so as to utilize the alimes and sands to seal the bottomof the system and reduce seepage. To reduce concentrations of thorium in theseepage, the licensee has deposited approximately 42 tons of } to 3 inch crushed,relatively soft, limestone below the tailings area. The seepage stream flowsthrough the limestone and is partially neutralized. This results in partialprecipitation of the thorium fmn the seepage stream thereby reducing concentra-tions of thorium released to the unrestricted area. Additionally, the licenseeplans to continue his program for monitoring the etnuent stream for radium-226,thorium-230 and natural uranium except for those periods of adverse weather condi-tions, suco as heavy snowfall (the licensee reports that at one time during thepast year the effluent stream was covered with 10 feet of snow). In view of theremote area in which the mill is located and the small quantity of seepage andconcentrations involved, we believe that it is sufficient to sample the streamon a weekly basis with monthly analysis of the weekly composits. In this respect,other uranium milling licensees discharging efnuents on a planned program arerequired to sample effluent streams at least hourly with monthly analysis of thehourly composits. However, this frequency of sampling does not appear necessaryin this particular case because of the reasons stated above.

In conclusion, it appears that the licensee is making a reasonable effort toreduce the amount of radioactive materials being released into unrestricted areasand that it is very unlikely that any individual vill be exposed in excess of10 CFR 20 limits as a result of the subject release. It is therefor recommended

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that an effluent authorization be granted on an interim basis until the licenseeobtains further data to evaluate his program for reducing both seepage and hethorium concentrations in the seepage. .

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asures amt Desial maaleer notertale arensh, as,aus F. assuessuures saa messel metaar astersale areneh, as,

spammaram to assammeg L2eran aspsmute zuro amassacras Amans,remeresses censur. samur st. 40-66pp

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he suh@est osapeer began armates asusag eyeseMans in early 1968. Prsar !

to essentsame, en angsmeersas ovatuntsam m e mese et the emeerlying stustaer es seaposes emitsass dispeemt seem to essertasm the edagnacy of theone ear tensase etassent. mas evalmensam smisestet est sospeso me< mith=1r heemsee er an unessaysag leper er sapervsame hentamate shene. newover, servey usertosame esse peersent is the event that soepace 414 esaur.escamm1 mouthe after spesutsame bassa, sospese une sheervet benew to ten-ense disposal etto ami am elsag one startet, per aussessmateap a year theesamententsame et mestem ass, thersum.a3o saa antesal asenten sa me eseposesure dose to tankersume sur teee esen. nosever, ensplaag eventeany estostes

! therem>R3D essesmesetsmo sa the oespace stream er appressem4ety a - 3 temos '

! the 10 GWR 801 smit asumeget over a ens year persas. Aseestsagny, the subdest '

1 11eemsee has regnestet en emmiytsam useer sostsam so.106 et 10 ma as, to 41.- 4

| eherse 11gesA eteneste satb unsestrastet areas. i,

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Ime reestremaste ear asyseval er en eenmem4 authertestsam emeer sostaan 30.186et part so ese that the esplieset kne mete a reasemakte erhet to assentee to

| snessentivity eestatest in etenesto to essestrieted esene ene that it toentesty that seesamettve matarsal esseberget sa the ofGment ses14 seemit sathe essesmee er en teetviemal to essesmesmessen et reesnestive matarsal essee6- '

sag the 1saste in part St. as this respect se espliemmt mest peerses sa$seur| tan esmessasas ernament new sense, eenment semessenettene et seassestive !

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setersale,/or salaset to the eiseberge, autiesystes ==amesatiano et seese-ehmessel amt phpetent peeperties et the stament, utter uses essen->

| eastes ame) estive emnersale as posses.er ester uses, koskasemat semesmerousse, emessen- !

j most munitorsag ess ===== w egassment, amt easte trestammt geweissano, one.

As motet above,- the seegese seemite fans appesent $malte sa es emeerlytagsessen er me easte tieposal seen amt 1. not a p1==a er entnesate mesherse,me paposent ama ah-a==1 yeepsettes et the eespace ese ensemeseny the ammeof tbmes of easte ligases hem any other esta lameb-ealvent estreetsam usunsenainsag guesses emosyt that ene esperiamme sm41estes the suspement selse een-,

| tsat et sempeen to usanny or as esseers. me clev sete et me eespese vertes. hetenen 25 est 30 saname per assete (en) emosyt eersag 30 to 60 eere sa thej spring den the nav is supplemembet ont Sumtet ny spring rue-ett. At fiev .

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me emuest miu is leestet la the oester of to harter Besia apprestaately,

| 3e air miles esse er gesper, grautag. me ares is semi-arid, esve14 et treesesa has very little sureene water emer een ageing sun-ett room netting amov.Dese is as emitivstet seemes witin 30 miles et the plant amt the messeetinhahttet asea is a usentes minias esop er esso 300 people leestet 5 miles teumthe plant site. De asesent pesumment se%1meent to the plant is lendisine Bow, '

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Wentag, same 3D mir milee asse. De only stream $a the seen is the LittleItseteine Bev River sieb is leested over 5 miles esem dry smilies tres the stilsite. Se 11eensee soports that this river has a aveseos fiev sete et sans ~~

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9 manien gallmes per ear. mese ese me teneum witbeseemis et water teen this 'river far either enlimary er istienties pumpesos between the mill" set the tous i

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Lj It ene aneuses that all et the eff1 ment (35 ga et 2 - 3 times the part 30 s

j limit) seashes he Little lessistas Bev River, these would he a 411utten tasteri et oppsestantear 1,000 at the avesnes ently flow sets of the river as reported! by the 11eensee. Beekasount one eeuestseen aseples obtaimet ny the liseasee

$atiente me esteetehle inerenses la semesatsetians et settenetivity $a es river,as egested, stase the affluent only renehes the river eering a 60 - 90 dayparted tem eetittanni 411stian is available. Sometase, there does not appearto be med puokshility of water neurons, at points et uses, botas ersected to asesses that $assummes ta restomotivity would he esteetehle.

| me liseasee, in an eteert to seense sospese ama estaentention et therten ta :i the aespage, has imetitetet a tee teld peegnum. W retnee sospege, the licensee '

f plans to sentimme his posestese for espeetting ta111 ass withis his tailtage || speten in ansk a asemer se as to utiliae the aliams amt menes to seal the betten '

et the ayates amt scenes esegnes. To seense eenesetsstimas et eartue ta theseepage,the11eenissehasdepositedappenstaatelyhatenset(to)tashestehet,sulatively soft,11asstems belev the tallings area. Se sospese sesema rieus,

!. thenush the limestene med is partsally asetsetiset. mas seemits in partial! psmespitanian et m e thorium trem t o esepage seseen enesty seensias seamentes.

tiens et therium sat ==a to the esseetrieted eses. Ae41u ny, the 11eenseep1mma to sentians his pressen fer amanterias the erfinant steese for seetua 386,' *

! (' tarina-230 amt materei usemina emeeyt ter these perises et adverse weather eenA1t tiles, seek as henry amoveell (the 11eemees suports est at one time eartas the 4"

neest. aves in mia m. min is leentet saa m. annu setity),.t . esp.go umapast year me stament stagen was seveset wie lo east et snow se view et the

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esmeentensions invalves, we believe that 14 is euttistant to semple the sesemaen a weekly tesis wie mentaar smanysis et the weekly eesposits. as was sospest,other usemium =8"*-liseneses eiesherging effiments en a plasmas peeseen see

/segasset to esople ehtaamat streens at least hourly with monthly amm1 pets of the ,v heurir esgreette. Sevever, this tre,sener et sempting enes met appear ameneaary

j ta this partientar ease beesmas et the swamens stated aheve. -

I In eenalmsteng it espears that the 11eenoes is asking a reasomahle effort toi reense the menuet at radioactive asterials betag released 1ste unrestricted areas! ^ n e. - , - ; . W^ ^ .en L. ^h : - r4- ^^ - ^ ^ ^ ^^

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