ML20126J535

Discusses Tasks II-b & II-c of NRC-02-80-076 & Provides Comments Re Specs for Addl Deep Well to Be Drilled by licensee.Goldberg-Zoino Hydrological Rept Was Received

ML20126J535
Person / Time
Site:	Wood River Junction
Issue date:	12/17/1980
From:	Dan Warner DON L. WARNER, INC.
To:	Shum E NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
References
CON-NRC-02-80-076, CON-NRC-2-80-76 18161, NUDOCS 8104290836
Download: ML20126J535 (6)

Text

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ROLL A. WSSOURI 6540 p December 17, 1980 Q

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Dear Dr. Shum:

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I am writing concerning Tasks II-b and II-c of flRC Contract 02-08-076 and also to provide my comments with regard to the speci-fications for the one additional deep well to be drilled by UNC.

In an earlier letter, dated November 3, I briefly discussed Task II-b.

Since that time, I have received a copy of the Gold-berg Zoino and Associates, Inc. ceohydrological report to United Nuclear Corporation.

The major value of that report is in the graphs that it contains of water quality data for 24 otservation wells at the UNC plant site.

Data are plotted for specific con-dJctivity, pH, nitrates, fluorides, gross alpha and gross beta.

Water level data are also plotted.

Plots are for the period of 1976-early 1980.

Data are not shown for all wells for the entire tire period.

Examination of the data for wells T-2, T-3, 76-U,77-B and 77-D shows that my earlier appra$sai (October 13,1980) of trends in water quality was correct as far as can be determined from the graphs.

Insofar as contaminant transport is concerned, it it apparent that the peaks for each of the major contaminants that are plotted (nitrate, gross alpha, gross beta) and conductivity (a contaminant indicator) appeared in well T-2 in late 1977 or during 1978.

Since that time, an irregular decline in contaminant levels continued up till early 1980, when the last data were plotted.

At that tine, water from well T-2 met drinking water standards for those para-meters measured.

Contaminant peaks appeared in well T-3 in late 1977 and early 1978 and concentrations generally declined af ter that time until early 1930.

However, secondary peaks of concentration occurred at various times during 1978 and 1979 and sore relatively high values even occurred in early 1930, indicating that contaminant fisshing in the near-lagoon vicinity is-not yet canalete.

THIS DOCUMENT CONTAINS POOR QUAllTY PAGES Y<

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Ob 1 82 61 8104200

Page two It w;uld be er:>et:sd that' maximum contaminant levels would occur spreanet later in wells 76-U, 77-B and 77-D than in wells l

T-2 an T-3.

This 's tecause the former three wells are located from 550 t: over :D'.0 feet further from the lagoon area than wells T-2 an: T-3 in :te direction of groundwater flow.

However, the i

' data s6:a that peat oncentrations occurred at wells 76-U, 77-B and

> D durin; 1977 a: 15:;; the same general time as peaks occurred in the. ells ' nearer rbe lagoon area.. Contaminant levels in the three wells. have de:line: markedly since 1977, but some values were still.acove drinkirq seter standards in early 1980 (see my letter of October 13, 1980.)

Fa::crs invoired in the understanding and interpretation of ground water contaminan; migration in the saturate: zone at the UNC site include:

1.

Y:lume of :.:nta.minated liquid' introduced, time-rate of introducti c, and contaminant concentrati:n.

i 2.

Details of 12;ifer geology, including ver:ical and lateral di ritation of the various aquifer materials (clay, sii, sind and gravel).

3.

Distributi:n Of the aquifer mechanica' pr:perties -

rosit;. E.

erreability - in three dire-sions-1 0-ber a:st'er :ro;erties, including:

longitudinal and la eral ci :ersivity, distribution coaffi:ients, vertical End horiz:- ei hydraulic gradient; and ra e and distribu-tion of ricnar;e.

5.

Geochemicai na ;re of liquid contaminants and ground water, l

includin; re:ay rates of radioactive contaminants, and in-1 genic or :r;inic chemical reactions that contaminants may l

undergo d, 'n; :cansport and viscosity ar.d density of both ii:uids.

?

F:r -an accu-a:e

.intitative prediction of c -taminant transport i

in the sir rated :: e, all of the factors listed a:ove must be known or reasonsble ass.meti:ns made.

In fact, almost r:ne of the factors are accara ely knra. s: that detailed modeling of contaminant trans-port, at'the prese ; ' e would largely be a trial and error process in an attarot to re:1 :Ett -he known history provided by the monitor wells.

l

'urther c: :~irition is that some storage :f contaminants in the ursa:, rated :: e res: likely occurred so that :ransfer of contami-nants #r:- the L Ii

,-t ed to the saturated zone is also involved.

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The rcs: eierentary quantitative 'estinate tr.E can be made is of the cys til average ground water velocity ir : e saturated zone from the it;;:n area to the Pawcatuck River.

Thi! is calculated using ths +:uation:

v=ki n

%:ere:

v = average ground water velocity [f-/ day]

k = hydraulic conductivity [ft/ day]

i = hydraulic gradient [ft/f t]

n = porosity [dimensionless]

From -he available information, an estimate ;# :ne average ground wa:+r velocity at the UNC site would be:

v = 150 ft/ day x 0.007 = 3.5 f t/ :aj 0.3 The I crtest distance from the lagocq area te he Pawcatuck River is aicut 1400 feet. The actual horizonta~ #~;w distance could be ; Ester.

Based on the shortest possible #~:w path, it would be ; ecicted that the average nonreactive ::. ar.inant particle would travel from the lagoon area to the river

r. L:0 days, about one year.

According to the Goldberg Ziono recort, thc' last confirmed spill or 1sak of liquid waste in the lagoon area 0::urred in April, 1978.

Ar.y conreactive chemical that entered the g cund water system at that tine would have been expected to have lar;e~y been flushed out befers :~B0, even allowing for significant tr :- in the calcula-tion of c.+ rage ground water velocity.

Possibit riasons for the continuing cresence of contaminants at the rel5-issiy high levels observec '- the downgradient wells include:

1.

5:r: tion of contaminants onto acuifer :E -icie surfaces i.<: subsequent release at a later time;-

2.

elayed movement of contaminants from.te ;nsaturated

ts into the saturated zone; 3.

e'e/ed movecent of contaminants in t e si rated zone by h

isr:orary entrcgrent in dead-end ler,se: :

c:ner structural

e-Page four t

W, I

cr stratigraphic traps.

4. 'LS;c:n leaks or -liquid waste s; i s cccsering after 1978.

l

'Regardless.of the correct explanati:

fsr-the slower-than-

- expected.fiashing of all contaminants fr:c tr.e aquifer at the UNC site, I would conclude that most contami ints have been flushed and that water from all of the wells wil' rest drinking whter standards within a few more years. The Ex:sotion to this.would be the introduction of additional contan'nar/;$ to the ground water during_ the decommissioning process, whic neuld simply delay still further the natural aquiferLclean-up prc:ess.

Task II-c asks,"What technologies c-procedures can be recommend-ed to speed up the purging of the underlyinc aquifer."

The possible methods would include:

1.

PL ping of existing wells loca id in the contamirant plume and/or installation of a::id: al umping nells in the plume.

This would draw ::n:2-irsqts fror the a;uifer at a rate faster than e > are raturally dis-charged.

Because of the diluti:t St nould occur during pumping the pumped water a ;1d probably rest j

standards for oirect discharge :

ne Piscatuck Eiver.

H wever, if not, then provisic,cLI: br.e to be ade i

f:r dilution or treatment :-i:r to cischarge.

2.

Development of injection wells.:;radient from the lagoon r

area to increase the hydrologic gradient and thus drive i

the contaminants more rapidly f cr. the aquifer.

j 3.

A combination of 1 and 2, in wn':n inje: tion wel'.s would be used to drive contaminants ::ah d :; cing wells and j

also to prcvide for dilution v.i:-ir :ne 2auifer.

4.

Ex.cavation of such contamina:et 3:41 as ay still be present in the vicinity of the 't;;ons to remove any remaining contamination source '. -he snallow sutsurface.

j At the present time, it is propose: trat one additional deep well be drilled at the UNC plant site.

e::crer.dations by the State j

and U. S. 3. S. for the well location a-: #:r tr.e drillir.g and samp-lir.g procedures to be used are containe:

'r en attachment to a letter 1

to the G0vernor's Office dated Septerber 23, 1950.

I pre /iously su; plied you with a copy of the letter E : :ne 'ecorrendations.

At i

the meetir; of October 28, which I arra :i: tre attended, and which i

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Page #1ve r

1 is reported in my re orancum of October 31 tc

and Mr. C

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it was agreed that each ' ;srested Darty nould pr; ide any i:di-tional tecnnical specif t:iti:ns for the well 'to L'C's consul ant, Goldberg Zoino Associa:es, Inc.

I have discussed tre well specifications $itn Michael ?:,.ers of Goldberg Zoino and.itn Herb Johnston and Ker, Kipp of -5e r

U. S. Geological Survey, and I have the follcwing :omments; 1.

The well locati:n is apparently a sc enhs arbitrar,.

I cne largely dicta ed by the wishes of the Rhode Islind CEQ.

The locati:n is not known to hi,'e any unique ;eolo-l i

.gic characteristics.

The reasoning Of tre DEQ was_: bat, if there should te contamination in 'ayer of finer-grained soil, it might n : yet have moved furtner than well T-6 and the contaminan s'=ight not be encounteret in a well placed r.earer the river.

I don't know of any reason that would cause another 1 :ation to be clearly I;;srior to the one that has been se'e:ted.

2.

I would recorre : tnat, to the exten

cssible a dalling rethod be used : it will Evoid the ree; i:r circuli-ing drilling fluids.

Two possibilities are ollow-sten augering and cable tool :-illing.

I would ore er the holl: -stem auger i

te used if it ':

e:".nically and ect : ': ally prac i al.

It c'gnt be r.ecessi y, a s: e depth, :: :ringe to ar: ner form of drilling, su:

is rud rotary or wasn toring.

It isn't-

ossible, at t 's ti e, to predict tre e> act combit.ition of crilling techni

,es that will be ros; sa::essful L.- this aspect of the Or:graa'should be consi ered very carsfully to insure that siroles of water and soil remain as uncon-taminated as pessiale by the drillin; or::ess.

i 1

3.

The sampling ; :;-t-that has been s;;;ested seems easonable, j

would sa;;es

it water samples

s :5.en by deid ng a well

oint into the

c;;;, of the drill

'e I: that wa ir will be obtained from

'sturbed zones.

4.

No cention is 4:e in the recomrend :i:t! concerni ; borehole

eophysical le;;'n;.

If successful, b;rshole logs :Ould pro-vide significan; information on the veri. al distr":ution of sediments and " ::r aminants in the ;r: rd water 1-d could also provide in-si ; values of pores' y # r later 1:udies by the U. S. Geol;;':E, Survey.

Desiratie 'ogs woul: :e porosity

[ neutron, tensi y, Or sonic), radicE::iv y (natur!' or spec-tral garra ra,.

3 c resistivity (pes #srt:'y a fc:. sed log cS;cble of eas.-in; true resistivi j iecause r# the lack

Page six d-

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,a c of availability of such logging devices fror cornercial sources, I would be inclined to suggest their use only if the U. S. Geolo-gical Survey can obtain one of. their lo;;ing trucks and if the dri.lling program can be designed so that the logs can.be run with-out interfering with other objectives anc at a-reasonable cost to UNC'.

I will be happy to provide any clarification or further dis-cussion of the items in this progress report as you might wish.

Sincerely yours, k cw " - -

Don L. Warner Consulting Geological Engineer DLW:kks a

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