ML20133K387
| ML20133K387 | |
| Person / Time | |
|---|---|
| Site: | Wood River Junction |
| Issue date: | 09/17/1985 |
| From: | Johnston H INTERIOR, DEPT. OF, GEOLOGICAL SURVEY |
| To: | Crow W NRC |
| Shared Package | |
| ML20133K389 | List: |
| References | |
| 25860, NUDOCS 8510210240 | |
| Download: ML20133K387 (30) | |
Text
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United States Department of the Interior
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GEOIDGICAL SURVEY W
T(JJt Water Resources Divison 70 eJpgb8 237 J.O.
Pastore Federal Bldg Providence, Rhode Island 02903 September 17, 1985 7
g e
e Mr. William T. Crow Q-U.S. Nuclear Regulatory Commission Mail Stop SS396 Washington, D.C.
20555 o
Dear Bill:
Enclosed is a copy of the report "Geohydrologic data for a low-level radioactive contamination site, Wood River Junction, Rhode Island" by Barb Ryan and others.
Let me know if you-would like additional copies.
Also enclosed are copies of two articles from USGS Water Supply Paper 2270~that' address the ground-water contamination. problem at the Wood River Junction plant.
I requested funding for follow-up sampling of ground-water at Wood Junction in FY 86, but chances of getting it seem slim.
Ken Kipp, who is doing the solute-transport modeling, said he plans to do some follow-up sampling, possibly in FY 87 or 88, but not in FY 86.
He said he didn't think he needed 1986 data "
to determine whether his model could accurately predict the fate of the contaminant plume.-
If the NRC would be interested in funding collection of' water quality data in FY 86 from selected wells in the monitoring
- network, give me a call. 'Perhaps we can work something out between your office and mine.
0 4
Sincerely yours,
\\
Docxato
/
6 unc
-2, 2
OCT 81985 t- :-.
Chief, Rhode Island Office Herbert E. Johnston 9'
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An Electromagnetic Method for Delineating Ground-Water Contamination, Wood River Junction, Rhode Island ByPaul M. Barlow and Barbara J. Ryan Abstract INTRODUCTION Surface electromagnetic (EM) surveys were conduct-Surface electromagnetic (EM) surveys were con-ed in August 1981 to delineate the areal and vertical ex-ducted m. August 1981 to deh.neate the areal and tent of ground-water contamination at a site in Wood River Junction, Rhode Island. The surveys were conduct.
vertical extent of ground-water contamination at a ed in conjunction with a 3-year study of low-level radio-site in Wood River Junction, Rhode Island. The active ground-water contamination from a cold-scrap re-surveys were conducted in conjunction with a 3-year covery operation (Ryan and Kipp,1983).
study oflow-level radioactive ground-water coatami-Surface electromagnetic induction techniques that nation from a cold-scrap recovery operation (Ryan measura terrane conductivity were used in August 1981 at and Kipp,1983).
a low-level radionuclide waste site in Wood River lunc.
Surface electromagnetic induction techniques tion, Rhode Island, to defineate areal and vertical extent that measure terrane conductivity have been found of contamination in a sand and gravel aquifer of glacial to be an effective tool in the preliminary assessment origin. Data from the terrane-conductivity survey were P
Y; gg consistrnt with values of specific conductance of ground water musured as part of a 3-year study of ground-water municipal contamination sites (Kelly,1976, p. 7; contamination at the site. Data from the terrane-and Greenhouse and Slaine,1983, p. 49; McNeill,1980b, specific-conductance surveys indicate that a plume of
- p. I 1). Electromagnetic induction techniques are a contaminated ground water extends from wastewater relatively inexpensive and reliable method of map-lagoons and trenches at the plant site to the Pawcatuck ping contamination plumes and may, in the early River. Above background terrane conductivities are pres-stages of a study of ground-water contamination, aid ent ovtr an area that is 370 meters in length, ranges in in the placement of water-quality observation wells width from 100 to 200 meters, and ranges in depth from (Greenhouse and Slaine,1983, p. 49).
land surface to 25 meters below land surface.
The ability of earth materials to transmit an Electromagnetic data were contoured in linear and electrical cu" rent is related directly to the electrical in dimensionless loganthmic units. Electromagnetic data c nductivity of the interstitial pore fluid and, to a contoured in linear units indicated high-conductivity zones thtt suggested potential ground-water contamina, lesser extent, the rock type. Electrical conductivity of tion. Line:r contouring also depicted changes in conduc.
the interstitial pore fluid (watet) is determined pri-tivity with depth more clearly than did the logarithmic marily by ion concentrations in the solution. As the contouring.
ion content of the pore fluid increases, the ability of Logarithmic contouring of electromagnetic data was the fluid to conduct an c!cetrical charge and the con-successfut in masking background noise, thereby de-ductivity of the carth material also increase, lineating boundaries of the contamination plume more The instrument used in the EM surveys consists dearly. Selection of background apparent-conductivity of an alternating-current transmitter' coil that produe-salues at the site for the loganthmic contouring schemes es a time varying magnetic field (primary field),
proved to be the greatest objection to the loganthrm,c which,in turn, induces small cddy currents m the method. Background values which were too high caused an unr:afistic reduction in the boundaries of the contami-carth (fig.1). These currents produce a secondary nation plume, whereas background apparent-conductivi.
magnetic licld, which, together with the primary tyvalues that were too low allowed interference from magnetic field, are intercepted by a receiver coil (Mc-background noise to bias the hydrogeologic Neill,1980b, p. 5; Evans,1982, p.105-108; Zohdy interpretation.
and others,1974, p. 55). Because the magnitude of An Electromagnetic Method for Delineating Ground. Water Contamination, Wood River junction, Rhode bland 35 i
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nondimensional contour units with a zero back-
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ground value; and, finally, the method of contouring 7
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= ' 4' logarithmie values is objective except for the choice M - - f_
of a background apparent-conductivity value.
This report summarizes the use of Eh! surs ey s to delineate a ground water contamination plume at h-
,4 a low-level radioactive waste site in Wood River um 4_
Junction, Rhode Island (fig. 2). The objectis es of
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this paper are to compare the results of Eh! surveys 7
to specific conductance measurements of ground
[7 water to eva'nate the ability of such a survey to delin-v m, "r. -.
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In this report, the results of horizontal-and ver.
Figure 1. Schematic model showing theory of electromag-tical-dipole measurements are included. It has been netic instrumentation and terrane-conductivity measure-ment. (A) Transmitter coil produces primary magnetic field noted (htcNeill,1980b, p. 6; Greenhouse and Slaine, (Hp);(6) Induced current loops produce a sec ondary mag-1983, p. 48) that data acquired from the vertical-di-netic field Oh). Relationship to eddy currents not shown; pole configuration are more commonly subject to (C) Current flow is achieved by the availability of c harged cultural interferences than data acquired from hori-particles in the sediments and pore fluids; and (D) Receiv-fontal-dipole configurations, blisalinement of coils er coil senses primary and secondary magnetic ficids-Conductivities are recorded' in the vertical-dipole configuration and a pro.
nounced departure from linearity of response at high the curreats induced by the transmitter is a function of hydrogeologic conditions, the magnitude of the ri'4r
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instrument (Evans,1982, p.108; hicNeill,1980b, p.
M 5). The relative contributions to the apparent con-ductivity of each of these factors need not be deter-j mined to interpret c!cctromagnetic data. Results of
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data collected from many traverses at a study site are f
adequate to indicate relative lateral changes in the N
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' n Greenhouse and Slaine (1983, p. 47-$9) sug-
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gested that the presentation of electromagnetic data c
s should be standardized by converting measured ap-N parent conductivity values to logarithmic ratios of
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measured values to background apparent conductivi-
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ty values. The dimensionless ratios then are con.
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logarithmic contouring of converted data over linear contouring of raw data: First, logarithmic contours of converted data do not cluster near the contaminant figure 2. toution of study area.
M 5 elected Papers in the ifydrologic sciences
vallies of terrane conductivity tiso m:y be c:uses for wells rc.nged from 150 to 5,000 pS/cm at 25'C; un-spurious readings in the vertical-dipole contaminated ground wates at the site generally had a configuration.
specific conductance ofless than 100 pS/cm at 25'C.
Specific conductance data indicate that a plume of SITE DESCRIPTION contaminated ground water extends from the plant area to the Pawcatuck River and adjacent swamp.
From 1966 to 1980, liquid wastes containing The plume is $20 m long and 100 m wide (fig. 4) and radionuclides and other chemical solutes were dis-is confined to the upper 25 m of saturated thickness, charged t3 lined lagoons at a cold-scrap uranium-w here sediments consist of medium to coarse sand recovery plant in Wood River Junction, Rhode is' and gravel (fig. 5). The top of the contamination land (fig. 3). Leakage from the lagoons resulted in plume is about 10 m below the water tabic between contamination of a highly permeable sand and gravel the plant and river, whereas contamination is en-aquifer ofglacial origin. Chemical constituents in countered at the water tab!c within the swamp area.
the contaminated ground water included nitrate, po-tassium, strontium 90,and technetium 99. Concen.
ELECTROMAGNETIC SUI 1VEY trations of nitrate and calcium, both of which were present in plant effluents, ranged from 3 to 600 mg/L Method and from 10 to 700 mg/L, respectively. Nitrate and calewm ions were the predominant constituents of The EM surveys were conducted in August the high dissolved-solids concentrations (as much as 1981 (Duran,1982) with c Geonics EM 34 3 induc-1,960 mg/L) in the contaminated ground water.
tive terranc-conductivity meter. Measurements Specific conductance of contaminated ground were obtained in both horizontal-and vertical-dipole water sampled from approximately 100 observation modes at 20.m intercoil separations, providing effec-
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o n na Figure 3. Location of observation wells and electromagnetic stations.
An Electromagnetic Method for Delinesting Ground Water Contamination, Wood River fun <tlon, Rhente Island M
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no no figure 4. Specific conductance of ground water, Wood River junction, Rhode Island, April 1982, tive depths of exploration on the order of 15 and 30 units. The first method (linear contouring) consisted m, respectively (fig. 6). A thorough explanation of of contouring apparent conductivity values from the electrical conductivity of soils and rocks and of field measurements at 1.0 to 2.0 mS/m at 25'C con.
the theory and operation of the Eh! 34-3 instrument tour intervals. Contouring of Eh! data in this man-has been given by hicNeill(1980a, b).
ner did not necessitate the determination of a back.
Eh! stations were located by pace and compass ground apparent-conductivity level. Therefore, no with the aid of aerial photographs. Data stations attempt was made to determine the level of back-were located midway between the transmitter and receiver coils (Duran,1982, p.106). Six traverses ground noisc [ natural scatter of terrane-conductivity values caused by " topography, spatial or temporal (lines 3-8) were made approximately perpendicular variations in the depth to water table, observation to the direction of ground water flow between the plant and the eastern bank of the Pawcatuck Iliver accuracy, lateral changes oflithology, and cultural interference from power lines, metal fences, etc.",
(fig. 7; table 1). On the western side of the river, one Greenhouse and Slaine (1983, p. 48)].
traverse (line 2) was made parallel to the river; this The second method of contouring follows the traverse then formed the ba\\is for several traverses recommendation of Greenhouse and Slaine (1983, p.
perpendicular to the river (line 1). Station spacings 49). They suggested the conversion ofdata to the were approximately 33 m, with the exception of those following logarithmic format:
located near the plant and in the swamp west of the Pawcatuck Itiver, which were 15 m apart, 20 logio u (background)
Linear and Logarillimic Confouring where a (x,y) equals apparent conductivity readings at any location on a grid with x and y coordinates Contouring of the electromagnetic data was and o (background)cquals the background apparent-done by two methods using linear and logarithmic conductivity value.
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Intervat in microslemens per centimeter at 25 C la verleble.
Figure 5. Specific conductance of ground water, Wood River Junction, Rhode Island, April 1982, cross-sectional view.
The dimensionless ratios (decibel units) ob-ties are present over an area 370 m in length by 100 tained from the logarithmic format for each station to 200 m in width; this is compatible with specific and the linear nondimensionless values then are con-conductance results (fig.14).
toured. The zero logarithmic contour [0 decibel (db)]
Although difficult to quantify, the vertical ex-then separates contaminated from noncontaminated tent of the high-conductivity zone has been qualita-areas. Contour intervals of 4 db, which were used in tively identified with the aid of effective depths of this study, correspond to incremental changes of a pcnetration for the horizontal-and vertical-dipole factor cf approximat:ly 1.6 abov: background appar-configurations (fig. 6). Contours oflinear vertical-ent conductivity, dipole data show local high-conductivity zones near the power substation and near the plant, where fences Results and transmission lines are concentrated (fig. I1).
These elevated conductivity values may be the result Data from the EM surveys indicate a high-con-of electrical currents produced by the power substa-ductivity zone at the site in an area which extends tion and power lines that interfere with the electro-from the plant to the Pawcatuck River and adjacent magnetic instrumentation or high ground-water con-s : amp (figs. 8-13). Above background conductivi-ductivity between 6 and 12 m below land surface [the An !!cctromagnetic Method for Delineating Ground Water Contamination, Wood River Junition, Rhode Island 39
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interval of the aquifer that contributes most to the may occur within the 6-to 12-m interval in this vertical-dipole configuration (ilg. 6)].
swampy area.
Vertical-dipole values remain high (5 mS/m at 25'C) from the plant to within about 100 m of the On the contrary, however, horizontal-dipole Pawcatuck River and indicate that some ground-measurements (fig. 8) remain low (2-3 mS/m at water contamination has t ccurred of 6 to 12 m below 25'C) to the east cf the Pawcatuck River but increase land surface. However, specific conductance values to between 4 and 8 mS/m at 25'C to the west of the indicate that t!.e most contaminated ground water is river in the swampy area. Because the greatest con-present 13 to 20 m below land surface near the river tribution to horizontal-dipole measurements is from (fig. 5). Because the maximum contribution to the near-surface electrical conditions (fig. 6), elevated vertical-dipole configuration occurs ia the depth in-conductivity measurements in the swamp may result terval between 0.3 and 0.6 percent of the intercoil from (1) the absence of a resistive, unsaturated layer spacing, the vertical-dipole configuration has not in the area,(2) the variation in grain size from uncon-sensed fully tFs high-conductivity zone. A greater solidated sa,d and gravel cast of the river to silt and intercoil spac ng (such as 40 m), however, may have organic matter in the swamp, or(3) a rise in the sensed this zone, Vertical-dipole values increase from electrical conductivity of the ground water. Although 4 to 6 mS/m at 25'C on the western side of the the absence of a resistive, unsaturated layer in the Pawcatuck River, which suggests that contamination swampy area probably adds to the overall increase in 40 Selected l' apers in the Hyrfrologic Sciences
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p Figure 7. Numbering systern of electromagnetic stations, conductivity levels there, c!cvated levels of ground-in a higher range of background apparent-conductivi-reater contamination are suspected. Horizontal-and ty values than to the east of the river, which consists vertic 1-dipole linear contouring of EM data show of unconsolidatest sands and gravels. To bring the clustering of contour lines in this area (Ggs. 8,11).
western and castern areas of the site into a common Logarithmic contouring schemes (Ggs. 9 and range of decibel values, higher values were assigned 10,12 and 13) were obtained by Grst assigning back-to the western side of the river than to the castern ground values to the logarithmic equation given by side.
Greenhouse and Slaine (1983). Background values at Differences in the ranges of apparent-conduc-the study site were obtained in the following ways:
tivity values for the horizontal-and vertical-dipole (I) By averaging the io,v apparent-conductivity val-modes also necessitated the use of two background ues for those stations which are believed to reflect apparent-conductivity values (one for the horizontal uncontaminated terrane conductivities and (2) by and one for the vertical conGguration)in each area of subjectively setting a background apparent-conduc-the site to the east and to the west of the river.
tivity value below which contamination does not Table 2 summarizes background apparent-con-seem likely, ductivity values used in this study.
B;ckground values are determined more easily Contours oflogarithmic data reflect above if the lithology of the study site is known. In the background conductivities from the plant to the river present study, the presence of a conductive, saturat-in the vertical and horizontal modes. Contours of ed, swampy zone to the west of the Pawcatuck River, horizontal-dipole values converted to averaged back-consisting of silt, clay, and organic material, resulted ground apparent-conductivity levels (6g. 6) show l
An Ilettromagnetic Method for Delineating Ground. Water Contamination, Wood River Junction, Rhode Mand 41
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Table 1. Electromagnetic data from horizontal and vertical dipoles at study area
[ Data in mi!!isiemens per meter at 25*C.;. no measurementi Electromagnetic Dymie
[lettromagnetic Dymie station Horizontal Vertical station Horizontal Vertgal Line I:
1.ine 4:
A 3.9 5.1 A
1.9 2.1 B
3.9 3.5 11 3.2 4.8 C
4.4 5.5 C
2.9 3.7 D
3.3 D
3.1 3.3 E
4.2 4.3 E
1.7 2.6 F
6.3 4.3 F
'6 G
4.9 6.4 Line 5:
11 3.5 3.7 A
t.8 2.3 I
3.9 3.3 H
1.8
!.7 3
- 4. t 4.I C
3.0 2.4 K
46 6.3 D
2.8 34 L
8.4 4.8 E
3.0 5.0 F
- 3. 5 4.8 Line 2:
G 2.0 2.6 A
2.3 3.4 11
'6 B
2.3 3.2 Line 6:
C 2.6 3.3 A
l.9 2.6 D
2.4 3.0 11 1.9
- 3. 4 E
2.4 2.5 C
2.2 32 F
2.9 3.0 D
2.9 5.4 G
4.6 6.0 E
3.2 5.0 II 6.6 4.9 F
t.9 2.6 I
9.0 6.0 Line 7:
J 8.5 5.7 A
t.4 2.5 K
7.2 6.5 11 t.9 5.2 L
9.7 3.4 C
2.6 40 M
7.2 5.8 D
2.5 5.0 N
6.2 7.2 E
I.5 2.5 0
3.7 5.5 I ine 8:
P 3.5 3.5 A
1.6 I.9 Q
3.4 3.4 11 2.8 2.7 C
1.0 1.8 Line 3:
D 3.3 5.0 A
1.8 2.0 E
3.2 5.6 B
2.3 3.4 F
4.4 7.5 C
48 4.8 G
3.3 8.4 D
2.6 4.6 11 4.4 13.0 E
I.8 3.3 I
3.2 6.2 F
2.5 J
1.8 2.6 I
higher decibel levels (8'db) in the swamp than to the DISCUSSION east of the river (as they did in the linear contouring scheme). Because lithologic variations have been The principal advantage of plotting terrane con.
masked deliberately in the logarithmic ratios, higher ductivities in dimensionless logarithmic ratios is that i
decibel levels probably reflect increased ground-it is possible to mask the contribution of background l
water contamination, which was suggested by the noise to the survey results; that is, local lithologie j
clustering oflinear contours in the swamp. Ilowever, variations, difTerences in the apparent and terrane if contamination has occurred in the swamp, it has conductivities resulting from variations in depth to been masked slightly by the second scheme of con-the water table due to topographic variations, cultur-touring logarithmic ratios in which a subjectively as-alinterferences, and inaccurate measurements. With j
signed background apparent-conductivity value was the data converted, identification of contaminated j
used (fir
.w.
zones is easier, inasmuch as any increase in the deci.
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g ge e
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believel indicates an increase in the apparent con-Linear apparent-conductivity values are spaced ductivity over and above w hat might be caused by more closely near zones of clevated contamination background noise.
and suggest that the plume is composed of a broad The selection of a background apparer'.on-zone of relatively lower contamination (2-3 mS/m at ductivity value for contours oflogarithmic ratios, 25'C in the horir.onta!-dipole configuration and 3-5 however, is quite subjective (Greenhouse and Slaine, mS/m at 25'C in the vertical-dipole configuration) 1983, p. 49) and presents the greatest drawback to with zones of relatively higher contamination near this method of data presentation. Difficulties were the plant and in the swamp. Although linear contour-found with both techiques for determining back-ing of apparent-conductivity values does not i,how a ground values used in this study. If too low a back-continuous zone of contamination as clearly as does ground value is used, local lithologic variations may the logarithmic contouring of apparent conductivity obscure the hydrogeologic interpretation (as with ratios (due to local variations in lithology and cultur-contouring oflinear values). Conversely, too high a al interference), linear contours emphasite high background value will not giv: sufficient definition levels of contamination, thereby outlining areas of of the boundaries of the plume, thereby masking ar.
possible importance.
eas of potential contamination. The authors propose Contours oflinear values also portray the dif-that both methods of determining background appar-ferences in vertical and horizontal electromagnetic ent-conductivity values be used in the contouring of results more c!carly than the logarithmic format. This logarithmic ratios. Low background values will then is especially true west of the Pawcatuck River where aid in the delineation of the boundaries of the plume, linear contours show high levels of conductivity in chereas high background values will show most the upper layers of the aquifer.a Differences between clearly the core of the contamination plume.
horizontal. and vertical. dipole results are not seen as An tiectromar ictic Methmt for Delineating GrountLWater Contamination, Womi River lunt tion, Rhoele liland 43
v,_._._..-_.--m.
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o to e Figure 9. Logarithmic contouring of horsiontal. dipole electromagnetic data using averaged badground salues, clearly with contours oflogarithmic ratios because tion was helpful in qualitatively determining shallow different background apparent conductivities were versus deep levels ofcontamination, used purposefully with horizontal and vertical con.
Contouring of the Eh! data by linear and loga.
figurations to put all values at the site into a similar rithmic methods shows that advantages and disad-range. As a result, contour, oflinear values are more vantages are associated with each method. Advan.
helpfulin determining the relative depth orcontami-tages to the linear method of contouring include an nation than are the contours orlogarithmic ratios.
emphasis on high-conductivity zones that are poten-CONCLUSIONS tial contamination source areas and better depiction of differences in the response of the horizontal and Results of Eh! surveys at a low level ra-vertical-dipole configuration with depth. Ilowever, dionuclide ground water contamination site indicate interference from background noise and some uncer-that areas of high apparent conductivity coincide tainty in delineating boundaries between contaminat-with areas of high specific conductance. hicasure-ed and uncontaminated areas of the site create ments in horizontal and vertical dipole configura-problems in the hydrogeologic interpretation oflin-tions indicate chemical stratification that is con-early plotted Eh! data.
firmed by specific conductance samples from wells The ability to mask the contribution of back-screened at various depths in the aquifer. Specific ground noise to Eh! survey results, thereby outlining conductance results do show, however, that contami-rnore accurately areas orcontamination, la 6he princl.
nation has occurred at greater depth than has been pal advantage to logarithmic contouring. The selec-sensed by the 20 m intercoil spacing of the vertical-tion of background apparent conductivity values at dipole configuration. The vertical-dipole configura-the study site posed the greatest drawback to logarith.
44 selected l'apere in the if ydrolosic s(lentes l
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mically contoured data. Dackground values that American Chemical Society Symposium Series, No, cere too high caused an unreal reduction in the 204 Risk Assessment at liaiardous Waste Sites. F. A.
boundaries of the contamination plume, whereas low Long and G. E. Schweitier,cds., p.93-115.
background apparent conductivity values allowed in-Greenhouse, J. P., and Slaine, D. D.,1983, The use of terference from background noise to bias the reconnaissance electromagnetic methods to map con-hydrogeologic interpretation, taminant migration: Ground Water htonitoring Re.
view, v. 3, no. 2, p. 47-$9.
SELECTED REFERENCES Kelly, W. E.,1976, Geoc!cetric sounding for delineating groumbwater contamination: Ground Water, v.14, Dickerman, D. C., and Silva, P. J.,1980, Geohydrologic no.1,p.6-10.
data for the Lower Wood River ground water reser-soir, Rhode Island: Rhode Island Water Resources hicNeill, J. D.,1980a, Electrical conductivity of sods ar'd Board Water Information Series Report 4,193 p.
rocks: Geonics Limited Technical Note T N-!, hiissis-Duran, P, D.,1982, The use of electromagnetic conductivi, sauga, Ontario,22 p.
ty techniques in the delineation of ground water con.
1980b, Electromagnetic terrane conductivity mea-tamination plumes, tri The impact of waste storage and surements at low induction numbers: Geonics 1.imit-disposalin ground water resources: Proceedings of the ed Technical Note TN-6, hiississauga, Ontario, I $ p.
Northeast Conference,Ithaca, N.Y., June 27t-July 1, Ryan, H. J., and Kipp, K. L.198 3, Ground water contam-1982, U.S. Geological Survey and Center for Environ-ination plume from low lesel radioacthe wastes, mental Research, Cornell University, p. R.4.1-8.4.33.
Wood Ither Junction, Rhode Island (abs): Transac.
Evans, R. D.,1982, Currently available geophysical meth-tions of the American Ucophysical Union, v 64, no.
ods for use in hasardous waste site insestigations:
18,p.224.
An Ifetfromagnetic Methad for Delineating r;round Water Contamination, Wood Riser lum tion, Rhode liland 41
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Slaine, D. D.,1983, Predicting the response of mapping Zohdy, A. A. R., Eaton, O. P., and Mabey, D. R.,1974, i
subsurface contamination with inductive conductivity Application of surface geophysics to ground water in.
techniques,in 1983 Technical Education Session:
vestigations: Techniques of Water Resources Investi.
j Ground Water Technology Division, National Water gations of the U.S. Geological Survey, Dook 2. Chapter Well Anociation,34 p.
U l,116 p.
L e
f 5
46 Selesfed l' apers in the flydrologic hlen<es 1
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An tiectromagnetic Method for Delineating Ground Water Contamination, Wood River fue,ction, Rhode Islan f % p'. c ?
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I 1
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k 48 Selected Papers in the Hydrologic Sciences e
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lable 2. Background apparent-conductivity values used to normalize the eleitromagnetic data
( All salues in mithsiemens per meter at 25'Cl Dipote orientation Vc rtical Horizontal Values East West East West Averaged ----------------
2.4 3.3 1.7 3.3 Assigned - - - - - - - - - - - - - - - - -
3.0 d.0 2.0 4.0 1
An Electromagnetic Method for Defineating Ground-Water Contamination, Wood River Junction, Rhode Island 49
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i Low-Level Radioactive Ground-Water Contamination From a Cold-Scrap Recovery Operation, Wood River Junction, Rhode Island ByBarbara J Ryan and Kenneth L. Kipp, Jr.
S (qi 1
Abstract INTRODUCTION u wasm e ntaining rahnuch in 1981, the U.S. Geological Survey began a 3-year study of ground-water contamination at a uranium-ther chemical solutes from an enriched ura bearing cold-scrap recovery plant at Wood River lunction, cold-scrap recovery plant have Icaked from poimny-Rhode Island. Liquid wastes from this industrial site were lene-and polyviny! chloride (PVC)-lined ponds and discharged to the environment through evaporation trenches into a highly permeabic sand and gravel aq-ponds from 1966 to 1980. Leakage from the uifer in southern Rhode Island. The resultant plume polyethylene-and polyvinyIchloride-lined ponds resulted ofground-water contamination extends about 2,300 in a plume of contaminated ground water that extends ft from the ponds and trenches to the Pawcatuck from the ponds northwestward to the Pawcatuck River through a highly permeable sand and gravel aquifer of River and the contiguous swamp into which ground-i di'I "E'"-
water discharge occurs. In 1981, the U.S. Geological Electrical conductivity, determined by Survey began a 3-year study of this ground-water electromagnetic methods, was used to delineate the contamination at a plant at Wood RiverJunction, plume areally before observation wells were mstalled.
p Y
These data, combined with water-quality data from more to (1) identify constituents in the plume,(2) deter-j i
than 100 observation wells, indicate that the plume is mine solute interaction with aquifer materials. (3) approximately 2,300 feet long and 300 feet wide and is model ground-water flow and solute transport in the confined to the upper 80 feet of saturated thickness study area, and (4) use the model to predict residence where sediments consist of medium to coarse sand and times in the aquifer and fate of contaminants in the gravel. No contamination has been detected in fine sands plume.
and silts underlying the co.arser materials. Piezometric head and water-quahty data from wells screened at Contaminated ground water at this site moves multiple depths on both sides of the river indicate that through a highly permeable glacial outwash aquifer contaminants discharge to the river and to a swampy area that yields water readily to wells. The Rhode Island
- tthe west edge of the river. Dilution precludes detection We Rem BM h whN n MlW of contaminants once they have entered the river, whic h around Wood River Junction and has considered de-nas an average flow of 193 cubic feet per second.
veloping ground water from the Meadow Brook Water-quality data collected from April 1981 to June Pond area for use both within and outside the basin.
1983 in;bcate that strontium-90, technetium-99, boron, The possibility that supply wells developed in the nitrate, and potassium exceed background concentrations area might be contaminated as a result of migration byan order of magnitude in much of the plume.
ofcontaminated water beneath the Pawcatuck River Concentrations of gross beta emitters range from 5 to 500 is of concern to the Water Resources Board.
ScoCuries per liter. No gamma emitters above detection evels hase been found. Electrical conductivity of the By October 1982, most of the data collection
+ater ranges from 150 to 4,500 micrombos per centimeter network for the investigation was in place, and rou-it 25 degrees Celsius. Water-quahty sampling shows line water-level measurements, water-quality sam-
'ones of concentrated contaminants at both ends of the pling, and precipitation measurements were begun.
Jume, separated by a zone of less contaminated water.
This paper describes geohydrologic conditions at the aboratory tests for exchangable cations indicate little site, the source ofground-water contamination, and apacity for uptake by the coarse sediments. In the presents preliminary findings based on data collected
- amp, reducing conditions may promote observable through June 1983. National Geodetic Vertical Da-ofute interaction with sediments or organic material.
Zum of 1929 is referred to as sea level in this report.
Low-Level Radioactive Ground-Water Contamination from a Cold scrap Recovery Operation, Wood River lunction, Rhode bland 2 t h
_,1 p WY MC
- - - - - - - - - - - - - ~ ~ - -
__ m n_..._n__._ _ M M
- %_am and trenches indicate that much of the liquid w aste
...',',I
discharged to the ponds and trenches did not evapo-
[ g.
f rate but rather percolated into unconsolidated depos-
- /
its beneath the site.
/
l M
Al;;
)
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The depth of the ponds and trenches ranged 4'.
from 3 to 15 ft below land surface; the bottoms of the 1
j ponds were 9 to 13 ft and the bottoms of the trenches I
/P.. m.m.
were I to 3 ft above high water table.
/
"7 From 1964 to 1966, liquid wastes were dis-
.m.
a.
/
@'.7,'7;:n,,- -
charged to the Pawcatuck River through a buried
- ~'-
drain 1,500 ft in length. lleginning in 1966, liquid i
/
' wastes were discharged into a pond approximately
w
,,,~j 5,000 ft in area and 6 ft in depth (fig. 2). Pond
)
capacity or overflow problems due to precipitation 4
and disposal flow rates (estimated by plant officials N,
[
CE to.have averaged about 400 gal /d) led to periodic
", ' S construction of additional ponds and trenches. In
., o m
.,,n
'* m
/
1967, a second pond (8,400 ft in area and 4 ft in Is5'((l.*[*j.7,7i*
N f
depth) was used as a replacement, and, in 1972, a new pond was constructed in the same area as the N
, y
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original pond. A series of trenches were built to N
..'N replace the first and second ponds in 1977 and w ere C
\\
used until 1979. The liquid waste disposal ponds and N' [
trenches encompassed approximately 25,000 ft:.
N-s N These disposal sites are considered to be the source of the contaminated liquid pc ;olation to the water table. In 1979, a covered tank with a double poly-Figure 1. Location of study area.
ethylene liner was constructed 50 ft north of the orig-inal pond area (fig. 2) to hold the liquid w aste during evaporation and concentration processing. To date, no evidence exists for ground-water contamination from the covered tank storage area.
PLANT HISTORY AND CONTAMINATION llecause data on chemical composition and SOURCE physical properties of the liquid wastes are limited and concentrations of chemical and radiochemical From 196I to 1980, an enriched uranium cold-constituents in waste discharges changed with time, scrap recovery plant was operated (fig. 2) at Wood defining the actual source loadings is not possible. In River Junction, Rhode Island. Acid digestion with addition to hydrofluoric and nitric acids, tributy!
hydrofluoric and nitric acids and organic separation phosphate, and kerosene, the fo!!owing chemicals with tributyl phosphate and kerosene were used in were used in the recovery process and were present in the process. Solid wastes from the process were the liquid wastes in varying concentrations: alumi-shipped offsite, and liquid wastes were discharged to num nitrate, calcium hydroxide, mercury, souium the Pawcatuck River through a drain pipe from 1964 carbonate, sodium hydroxide, and potassium hydrox-to le 66 and to uncovered " evaporation" ponds and ide. Although primarily nonirradiated fuel elements trenches from 1966 to 1980.
were processed from 1964 to 1980, slightly irradiated In southern Rhode Island, however, average an-fuel c!cments from test reactors were processed from nual precipitation is much greater than average annu-1967 to 1980. This could account for the strontium-al evaporation; for example, from 1950 to 1970, pre-90 and technetium-99 that are in the contaminated cipitation at the National Weather Station at water.
Kingston, Rhode Island,9 mi northeast of the study.
Processing at the plant, which ended in August area, averaged 46.06 in/yr while estimated annual 1980, currently is being decommissiontd. Material free water surface evaporation for the same period from the bottom of the ponds and trenches and sedi-was only 29 in/yr(National Oceanic and Atmospher-ment from below the ponds and trenches were re-ic Administration,1982). This and the fact that moved and combined with a cementlike mixture and highly permeable sediments occur beneath the ponds shipped ofTsite for burial. Sediments in the unsatu-22 Selected Papers in the if ydrologic sciences
N d
Unpaved roads covered tank N
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,,n l
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Figure 2. Location of processing area, evaporation pond, trenches, and covered tank in 1979.
rated zone between the pond and trench bottoms and the plant and the river that ranged in depth from the water table were not sampled.
approximately 50 to 80 ft. Water-quality data ob-tained by the company from one of these wells indi-cate ground water of high conductivity (14,500 PREVIOUS SITE INVESTIGATIONS mho/cm at 25*C), high nitrate (2,200 mg/L). and significant gross beta emitters (1,518 pC/L) 200 ft From 1974 to 1977, the Rhode Island Water from the source area (D okerman and Silva,1980, p.
Resources Board drilled approximately 20 test holes 177-178).
on the plant property to obtain lithologic and water.
In 1977, resistivity surveys were conducted by quality data for evaluating potential areas for David liunticy, University of Connecticut, and by ground-water development. Water-quality data ob-Daniel Urish, University of Rhode Island. Results of tained as part of the Water Resources Board investi.
these surveys indicated a plume of ground water with gation indicate ground water of high conductivity high conductivity between the plant site and the Paw-(5,500 pmho/cm at 25'C), high nitrate (225 mg/L),
catuck River. Adjacent to the source area, depth and significant gross alpha (43 pC/L) and gross beta below land surface of the highest conductance water (489 pC/L) emitters 1,100 ft from the source area was estimated to be 40 ft (David fluntley, written (Dickerman and Silva,1980, p.177-178). In 1977, commun.,1981). Maximum known extent of con-the company installed 10 observation wells between tamination at the start of the present study (October i
tow-Level Radioactive Ground-Water Contamination from a Cold Scrap Recovery Operation, Wood River Junction, Rhode Island 23 9
L A
wa-
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F 1982) was approximately 1,200 ft from the source Hydrology area.
The plant site, located within the lower Paw-catuck River basin, is approximately 2 mi cast of the junction of the Pawcatuck and Wood Rivers. Uncon-solidated deposits near the junction of these two riv-ers comprise the most extensive accumulation of sed-STUDY AREA DESCRIPTION iments in the lower Wood aquifer (Gonthier and others,1974, p. 7). The aquifer is approximately 8 Geology mi in length and ranges from 2,000 to 8,000 ft in width with the majority ofit extending north, north-The study area is underlain by the llope Valley west, and west of the plant site. Saturated thickness Alaskite Gneiss, a metamorphic rock unit of Late in the Ellis Flats area exceeds 290 ft. Swamp and till Proterozoic age (570-900 million years old). The deposits form the southern and eastern limits of the gneiss was an igneous rock unit that underwent one and possibly two episodes of metamorphism (hfoore, aquifer, respectively.
The aquifer is unconfined with a water table 1959). The bedrock crops out cast, northeast, west, and southwest of the study area, and unconsolidated that slopes westward from the plant site at an average glacial deposits of Pleistocene age (less than I million gradient of 28 ft/mi. The lower boundary of the years old) have been deposited on top of the bedrock.
aquifer is the bedrock surface (fig. 4). Generally, Glacial till deposits (poorly sorted clays, silts, ground-water movement in the aquifer is from the lateral boundaries or till upland areas toward the sands, gravels, and boulders) form a relatively thin Pawcatuck River (fig. 5). Ground water discharges to (less than 20 ft) mantle over the bedrock (LaSala and the Pav catuck River, which is the major surface Hahn,1960) and appear at land surface cast of the plant site (fig. 3). Glacial outwash deposits (well-water drainage from the study area. Ground-water sorted silts, sands, and gravels) were deposited in the potentials (fig. 6) show upward vertical movement of bedrock valley (fig. 4) and range in thickness from 0 water into the Pawcatuck River and contiguous to 300 ft in some parts of the valley.
swampy area west of the river.
In the bedrock valley, the outwash deposits con-Water enters the ground-water system through sist of predominantly medium to coarse sands and infiltration of precipitation (rainfall or snowmelt).
gravels to a depth of about 80 ft below land surface Overland runoff and some ground-water flow from and mostly fine sands and silts below a depth of 80 ft adjacent till-covered bedrock areas also enter the aq-(fig. 4). A glacial terminal moraine (till with some uifer. Based on annual average runoff of 27.51 in stratified deposits) approximately 3 mi south of the from 1966 to 1980 upstream of the U.S. Geological study area may be responsible for the fine sands and Survey gage on the Paweatuck River at Wood River silts at depth. Slow-moving glacial meltwater flowing Junction and a relation developed by htazzaferro and into a lake behind the moraine apparently resulted in others (1978, p. 45), long-term avcrage annual
~
the deposition of the fine-grained sediments.
recharge to the aquifer is estimated to be 26 in/yr.
The fine sands and silts are cohesive in places; Assuming ground-water outflow is a conservative es-however, few clay-sized particles have been found to timate of the amount of naturai recharge, blazzaferro date. Clay-sized particles from two split spoon sam-and others (1978) related ground-water outflow to ples taken from the fine sand and silt unit were 2.94 the percentage of stratified drift in a drainage basin.
g and 3.07 percent. Clay-sized particles taken from The relation developed by linear regression is de-seven split spoon samples from the coarse sand and scribed by the equation, gravel unit ranged from 0.12 to 7.60 percent, with an Y = 35 + 0.6X' '
average value of 1.53 percent and's median value of O.38 percent. In two locations (one approximately where Yequals ground-water outflow as a percent of 100 ft south of hieadow Brook Pond and one be-total runoff a'nd Xequals percentage of total basin tween the plant site and river) where test holes have
. area underlain by stratified drift. For this case, X =
exceeded 150 ft in depth, a zone (5-15 ft) of coarse
~100.
sands has been encountered below the line silts and Discharge of water from the aquifer occurs sands and above the bedrock surface. The mineralo-through ground water runoff and evapotranspiration,,
gy of the outwash deposits is predominately quartz primarily where the water table is near the land sur-and feldspars; dark minerals (biotite and hornblende) face. flydraulic conductivity of till is estimated to are generally more abundant in the finer sediments average about I ft/d as does the till in the nearby (F.T. hianheim, written commun.,1983).
upper Pawcatuck River basin (Allen and others,-
24 selected hpers in the Hydrologic Sciences
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0 300 600 METERS RHODE ISLAND
- Providence
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Line of geologic section Figure 3. Generalized surficial geologic map of the study area and location of cross-sectionalline A-A'.
tow level Radioactive Ground-Water Contamination from a Cold Scrap Recovery Operation, Wood River lunction, Rhode Island 25
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DISTANCE.lN METERS VERTICAL EXAGGERATION X27 Figure 4. Generalized geologic section along line A-A'.
1966, p. 9), whereas hydraulic conductivity of out-Uncontaminated ground and surface water in j
I wash deposits at the plant, estimated from lithologic the study area generally meet U.S. Environmental i
logs,is about 180 fvd (Gonthier and others,1974, Protection Agency (1976) drinking water standards.
plates 2,4). Hydraulic conductivity determined from Specific conductance, an indication of dissolved min-analyses of three aquifer tests made within a 1 mi erals in the water,is generally less than 100 pmho/cm radius of the site, including one on the plant supply
. at 25*C, Principal cations, sodium, calcium, potassi-
~
well(fig. 2), ranged from 140 to 190 fud (D. C. Dick-um, and magnesium are present in concentrations of erman, c,ral commun.,1983). Hydraulic conductivity 14 mg/L or less; principal anions, sulfate, chloride, of the fine sands and silts at depth probably falls.
and nitrate are present in concentrations of 20 mg/L L
somewhere in between those of the tills and coarse or less. Some naturally occurring radionuclides, such j
outwash deposits. Fractures in the bedrock also yield as potassium-40 (1 POL), radium-226 (3 POL), radi-H water to wells but generally only enough for domestic um-228 (2 POL), and strontium-90 (3 POL), have
. supplies (5 g. ' min or less)(Allen,1953, p. 26).
been detected in ground and surface water in the Ground-water flow, which was calculated from a study area.
F water-table gradient of 28 fumi, an estimated aquifer l
porosity of 0.38 (obtained from averaging porosity EXPLORATION TECHNIQUES values from six sediment samples), and hydraulic-conductivity estimates that ranged from 140 to 190 Geophysical techniques and well drilling were ft/d, ranged from 1.95 to 2.65 fUd.
used to define the hydrogeologie systein and contam- ';
26 Selected Papers in the Hydrologic Sciences E
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Observation wolt X
X Fonco figure 5. Average water-table altitude frorn July 1982 to June 1983; location of observation wells and cross-sectional line B-B'.
- Low. Level Radioactive Ground. Water Contamination from a Cold Scrap Recovery Operation, Wood River Junction, Rhode Island 27
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DISTANCE FROM SOURCE AREA,IN METERS EXPLANATION 4 8- - Equipotential line. -- shows altitude at which water level would have stood in tightly cased well. Contour interval,1 f oot f,{
Bedrock Screened interval in observation wells l
l Fine sand and sHt VERTICAL EXAGGERATION X10 Figure 6. Hydrogeologic section showing average ground-water potential frorn July 1982 to June 1983.
ination plume. Geophysical techniques included to locate areas within the aquifer containing water of seismic refraction to determine depth to bedrock, ge-high specific conductance.
ophysical well logging (gamn a gamma, natural gam-More than 135 observation wells ranging in ma, and neatron) to determine relative lithologie dif-depth from 10 to 230 ft were installed during six ferences within a given well and from well to wel!.
drilling phases using hollow-stem auger, mud rotary, and electromagnetic (inductive) conductivity surveys and drive-and-wash methods. Wells generally were 28 Selected l' apers in the Hydrologic Sciences
' construc'ted ofi% to IW-in diameter flexible poly-tered the river which has an average discharge of 193 ethylene or rigid PVC plastic pipe. Two wells were ft'/s. The plume is approximately 300 ft in width and constructed with 5-in diameter rigid PVC pipe for is contined to the upper 80 ft of saturated thickness geophysical logging purposes, and two wells were (fig. 9) where sediments consist of medium to coarse constructed with 1%-in diameter galvanized steel for sand and gravel. The top of the contamination continuous water-level recording. Screened intervals plume is depressed below the water table, and its or well points ranged from 2 to 10 ft in length and depth increases as it moves away from the source were either No. 10 (0.010-in) or No. 12 (0.012-in) area. The plume obtains a maximum depth (80 ft slot. The first drilling phases were used to install below land surface) between 1,400 and 1,500 ft from relatively shallow (less than 30-ft) observation wells the source area. Beneath the discharge area (river to 'etermine the water-table configuration. Later and adjacent swamp), the plume rises to land surface.
phases were devoted to the installation of wells rang-Specific gradty of three samples of contaminat-ing in depth from 10 to 100 ft to locate the contami-ed ground water collected in 1981 ranged from 1.000 nation plume horizontally and vertically. Ten split to 1.001 (Daniel Urish, written commun.,1982). It spoon samples were taken for such sediment analyses is assumied, therefore, that freshwater recharge on top as cation exchange capacities, mineralogic descrip-of the plume is probably responsible for increased tions, porosity tests, and sieve analyses.
depth of the plume away from the pond area. Sea-sonal variations in hydrologic conditions may affect CONTAMINATION PLUME dimensions of the plume; for example, high precipi-tation in the spring of 1983 depressed the contamina-The plume of contaminated ground water ex-tion plume below the water table at the river-s. vamp tends from the source area northwestward approxi-interface (fig.10).
mately 1,500 ft to the Pawcatuck River and south-Chemical and radiochemical constituents in the westward approximately 800 ft in a downstream contaminated water include nitrate (5-600 mg/L),
direction through the swampy area west of the river, boron (20-400 pg/L), potassium (3-25 mg/L), stron-a total distance of 2,300 ft (figs. 7,8). Dilution pre-tium-90 (4-250 pC/L), and technetium 99 (75-1,350 cludes detection ofcontaminants once they have en-pC/L). Due to the expense of the analytical procc-oo, ism.o y
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Figure 7. Strontium 90 concentration in ground water at the plant site, October 1982.
Low. Level Radioactive Ground. Water Contamination from a Cold Scrap Recoscry Operation, Wood River lunf tion, Rhode Island 29 pea %WyB WMw -+
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dure, only five water samples have been analyzed for processing mater,al (1964-80). The zone near the vecluietium-99 (two by the U.S. Geological Survey source area appa ently resulted from flushing of addi=
and three by Oak Ridge Associated Universities). In tional contaminz.its from the unsaturated zone while these five samples, strontium-90 accounts for 10 to the sediment be'ow the ponds and trenches was being 30 percent of the gross beta activity; the remainder is excavated for site-decommissioning.
c.ttributed to technetium-99. The sums of strontium-Sediment-and water-quality analyses from 99 and technetium-99 actually may exceed the gross sampling locat: ens fiom the plant to the river ir di-beta activity level for a given sample; this is most cate chemical and radiochemical constituents a'ce not likely due to the fact that the separation and counting being sorbed by aquifer materials. Cation-exchange efficiency for individual radionuclide measurements '
capacities from five split spoon samples ranged from is greater than that of the gross beta counting appar-0.1 to 4.2 millicquivalent per 100 grams (meq/100 g),
atus. Concentrations of gross beta emitters range with a median value of 0.5 meq/100 g. Technetium-from 5 to 500 pC/L. No gamma emitters above de-99 and strontium-90 have been detected in water rection levels have been found. Electrical conductivi-from observation wells that are 1,500 and 2,000 ft, ty of the water ranges from 150 to 4,500 mho/cm at respectively, from the plant. In the swamp, however, i 25'C. Dissolved solids have been measured up to reducing conditions may promote observable solute 3,500 mg/L, and these concentrations interfere with interaction with sediments or organic material once the detection of alpha emitters. Concentrations of the plume rises to land surface. Additional sediment-chemical constituents in contaminated water at the and water-quality analyses are being conducted on plant site, and background concentrations are sum-materials from the swamp.
marized in table 1.
From 1982 to 1983, two zones of concentrated
SUMMARY
contaminants were present at both ends of the plume and were separated by a zone ofless contaminated Liquid wastes from an enriched uranium cold-water. The zone near the Pawcatuck River resulted scrap recovery plant have leaked into a highly perme. '
from infiltration of contaminants while the plant was able sand and gravel aquifer in southern Rhode Is-30 Selected Papers in the Hydrologic scientes k
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DISTANCE front $0L*RCE AREA.IN METERS VERTICAL EX AGGER ATION X 10 Figure 9. Strontium-90 concentration in ground water at the plant site, October 1982.
land. The resultant plume of contamination extends basin, Rhode Island: U.S. Geological Survey Water.
2,300 ft from the source area (evaporation ponds and Supply Paper 1821,66 p.
trenches) to the aquifer's discharge area (the Paw-Dickerman, D. C., and Silva, P. J.,1980, Geohydrologic catuck River and swampy area west of the river).
data for the Lower Wood River ground-water reser-Dilution, however, precludes detection of contami-voir, Rhode Island: Rhode Island Water Resources nants once they have entered the river. Chemical Board Water Information Series Report 4,193 p.
and radiochemical constituents in the plume include Duran, P. B., and llaeni, F. P.,1982, The use of electro-nitrate, boron, potassium, strontium-90, and techne.
magnetic conductivity techniques in the delineation of tium-99. Unconsolidated deposits comprising the ground-water contamination plumes: Proceedings of aquifer contain few clay-sized particles, and contami_
the Symposium on the Impact of Waste Storage and Disposal on Ground-Water Resources, sponsored by nants do not appear to be interacting significantly with the sediments. In the swamp, reducing conds.-
the U.S. Geological Sarvey, and Cornell University, Ithaca, New York, June 28-July 1,1982,38 p.
tions may promote observable solute interaction with Gonthier, J. B., Johnston, II. E., and htalmberg, G. T.,
sediments or organic material.
1974, Availability of ground water in the Lower Paw-catuck River basin, Rhode Island: U.S. Geological Survey Water-Supply Paper 2033,40 p.
SELECTED REFERENCES LaSala, A. hl., Jr., and llahn, G. W.,1960, Ground-water map of the Carolina quadrangle. Rhode Island: U.S.
Allen, W. B.,1953, The ground-water resources of Rhode Geological Survey Ground-Water h1ap 9, scale Island: Rhode Island Development Council Geologi-1:24,000.
cal Bulletin No. 6,170 p.
Af azzaferro, D. L, Itandman, E. !!., and Thomas, A1. P.,
A!!en, W. B., llahn, G. W., and Brackley, R. A.,1966, 1978, Water resources inventory of Connecticut Part Availability of ground water, Upper Pawcatuck River 8, Quinnipiac River basin: Connecticut Water Re-Low-Level Radioactive Ground-Water Contamination from a Cold Scrap Recovery Operation, Wood River junction, Rhode Island 31 v-
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,g
~ ~- 10-.Lin. of eovat netrate concentrat n
-dash.d wher. appro s.mately 6.cated.
{
Intervai in meherams per ht.t 6s tarkable s10 I
I I s e,e.n.a.nt.r..i in ee..r..i n w.m.
I r ;',. '. - cl ',. 1.. -
c.
i,1s
..... ~ a.do, # ~ -
s 800 700 600 500 400 300 200 100 0
OtSTANCE FROM SOURCE AREA. IN METERS VERTIC AL E X AGGER ATION X 10 Figure 10. Nitrate concentration in ground water at the plant site, May 1983.
Table 1. Representative chemical analyses of water from observation wells near the middle of, the edge and outside the contaminant plume
[Results in milbgrams per liter except as indicated]
Observation Observation Observation well in middle well on edge well outside of plume, of plume, of plume.
Chemical constituent reb.17,1982 Feb.3,1982 Dec. 23,1981 Alkalinity-CACO, - - - - - -
7 3
9 Boron (pg/L) --------
230 50
<10 Cadmium (pg/L) - - - - --
1 2
<1 Cakium - - - - - - - - - -
720 50 4.1 Chloride - - - - - - - - - -
180 9.2 5.0 Copper (pg/L) ----- --
4 2
5 f luoride - - - - - - - - - -
<.1
<.1
<1 Hardness ---------
.,900 130 16 Iron (pg/L) - - - - - - - - -
250 20 310 Lead (pg/L) - - - - - - - - -
5 6
1 Magnesium --------
23 1.5 1.4 Manganese (pg/L) - - - - - -
600 67 1,600 Nickel (pg/L) --------
14 1
2 Nitrate (NO, + NO ) - - - - -
580 37
.18 3
pH (units) ---i-----
5.6 5.7 5.6 Phosphorus (ortho as P) - - - - - - - -
<.01
<.01
<.01 Potassium ---------
21 3.4 2.5 Silica -----------
<.1 11 6.9 Sodium ----------
25 7.8 4.4 Specific conductance
( mho/cm at 25'C) - - --
4,260 376 77 Strontium-90 (pC/L) - - - - -
222 6.7 2.9 Sulfat e - - - - - - - - - - -
50 14 14 Water temperature ("C) - --
12.0 11.5 10.5 Zinc (pg/L) - - - - - - - - -
50 11 16 32 Selected Papers in the Hydrologic 5(icntes
sources Ilulletin No. 27, 88 p.
Moore, G. E., Jr.,1959, Bedrock geology of the Carolina and Quonchontaug quadrangles, Rhode Island: U.S.
Geological Survey Quadrangle Map 117, scale 1:31,680.
.NationalOceanic and Atmospheric Administration,1982.
Evaporation atlas for the contiguous 48 United States:
NOAA Technical Report NWS 33,27 p.
U.S. Environmental Protection Agency,1976, Quality cri-teria for water-U.S. Government Printing OfTice, Washington, D.C. 20402, Stock No. 055-001-01049-4,256 p.
Low.tevel Radioactive Ground. Water Contamination from a Cold Scrap Ret:overy Operation, Wood River Junction, Rhede Island 33 l
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.g w.
m -
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