T.dinlcol Nat*
ORP/LV-76-4
REPORT OF AMBIENT OUTDOOR RADON A
INDOOR RADON PROGENY CONCENTRATIC
>URING NOVEMBER 1975 AT SELECTED LOCA
IN THE GRANTS MINERAL BELT, NEW MEXI
ND
NS
IONS
:o
JUNE 1976
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RADIATION PROGRAMS
LAS VEGAS FACILITY
LAS VEGAS, NEVADA 89114
-------
Technical Note
ORP/LV-76-4
REPORT 0V AMBIENT OUTDOOR RADON AND INDOOR RADON
PROGENY CONCENTRATIONS DURING NOVEMBER 197S
AT SELECTED LOCATIONS IN THE GRANTS
MINERAL BELT, NEK MEXICO
Gregory G. Eadie*
Robert V. Kaufmann*
David J. Markley**
Roosevelt Williams*
JUNE 1976
*OFFICE OF RADIATION PROGRAMS - LAS VEGAS FACILITY
U.S. ENVIRONMENTAL PROTECTION AGENCY
LAS VEGAS, NEVADA 89114
**U.S. ENVIRONMENTAL PROTECTION AGUJiCY
REGION VI, DALLAS, TEXAS
-------
UISCLAIMHR
This report has been reviewed by the Office of Radiation
Programs - Las Vegas Facility, U.S. linvi ronraental Protection
Agency, and approved for publication. Mention of trade names or
commercial products does not constitute endorsement or recommen-
dation for their use.
ii
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PREPACK
The Office of Radiation Programs of the U.S. I-nvironmenta
Protection Agency carries out a national program designed to
evaluate population exposure to ionizing and nonionizing radio
tion, and to promote development of controls necessary to prot ct
the public health and safety. This report describes a survey
conducted in the Grants Mineral Belt area of New Mexico to
evaluate the ambient outdoor radon and indoor radon progeny
concentrations. Readers of this report arc encouraged to info[rm
the Office of Radiation Programs of any omissions or errors,
Comments or requests for further information are also invited.
c
Donald IV. llendricks
Director, Office of
Radiation Programs, I.VF
111
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CONTENTS
PREFACE
LIST OF FIGURES AND TABLES
ACKNOWLEDGMENTS
SUMMARY AND CONCLUSIONS
RECOMMENDATIONS
INTRODUCTION
TYPES OF SURVEYS
Radiation Surveys
Ambient Outdoor Radon-222 Concentrations
Sampling System and Analytical Methods
Geologic Influences on Radon Concentrations
Results
Radium in Soil
Discussion
Indoor Radon Progeny Levels
Sampling System and Analytical Methods
Results and Discussion
REFERENCES
APPENDICES
A. Geologic Factors Affecting Atmospheric Rndon
B. Ambient Outdoor Radon-222 Concentrations
Tables B-l to B-9
C. Meteorology
D. Indoor Radon Progeny Determinations
Tables 0-1 to 0-9
Page
iii
vi
vii
1
2
3
5
5
8
8
8
13
16
17
21
21
21
23
25
30
35
41
Preceding page blank
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LIST OP VIGURUS
Number Page
1 Generalized Map of Sampling Locations
and Summary of Results 4
2 Typical Mine Ventilation Hxhaust l>uct 20
3 Mine Overburden or Ore Materials Used
as Landfill 20
A-1 Geologic Map of the Ambrosia Lake Mining
District and Vicinity 2?
C-l Daily Temperatures for November 1975 at
Field Location S802, Grants, New Mexico 37
C-2 Daily Temperatures for November 1975 at
the Grants Municipal Airport, .New Mexico 38
C-3 Barometric Pressure for November 1975 at
the Grants Municipal Airport, New Mexico 39
C-4 Kind Rose for November 1975 at Field
Location «S02. Grants, New Mexico 40
LIST OF TABLES
Number Page
I Radiation Sur\*cys d
2 Summary of Ambient Outdoor Radon-222
Concentrations and Indoor Kadon Progeny Levels 9
3 Summary of Kadon and Radium Analytical Results
and Geologic Characteristics for Sampling
Locations 11
4 Comparison of Average Radium and Radon Data 12
5 Lxposure Limits for Radon-222 and Radon Progeny 18
vi
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ACKNOWLEDGMENTS
ion
The authors would like to extend thc-ir grateful appreciat
to Messrs. Frederick B. Johns and Lewis A. Bunce of the U.a.
Environmental Protection Agency, Environmental Monitoring and
Support Laboratory (EMSL) - Las Vegas for their efforts in the
field support of this study. The assistance of New ?'c**c°
Environmental Improvement Agency personnel, Messrs. Theodore
Wolff and Jack Reynolds, and the cooperation of thc "e* *"V ..
dents in allowing sampling on private property is also gratefully
acknowledged.
vii
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SUMMARY AND CONCLUSIONS
This report presents the results of measurements of
outdoor radon' concentrations and indoor radon progeny w
level determinations during November 1975 for 10 locatio
throughout the Ambrosia Lake area and vicinity, New Mexi
that portion of the study area in the vicinity of uraniu:
and mills, statistical evaluation of the data indicates
ambient outdoor radon concentrations and the indoor rado
levels IKL) arc in excess of typical background levels.
definition of background levels and a more thorough cval
specific source terms in the immediate Ambrosia Lake are
strongly suggested. For locations in proximity to a ura
site, gamma radiation exposure rates and the radium-226
of surface soils arc also above normal background condit
This may reflect the deposition of windblown tailings an
dust. To assure compliance with State and Federal regul
it is recommended that further studies be conducted over
a one-year period for comparison to the applicable radio
protection guides for those areas in the vicinity of ura
sites. Radiation exposures to the general population oc
areas in the immediate vicinity of uranium mining and mi
operations should also be evaluated.
mbient
king
i. For
mines
at
progeny
ctter
tion of
is
uni mill
mtcnt
ms.
or ore
ions ,
t least
on
urn mill
ipying
ing
1. The term "radon" is u*cd »n this report to designate! the
radionuclide radon-222.
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RECOMMIT DATIONS
Analysis of the data generated in this report indicates
several problem areas which should he resolved if the environ-
mental effects of uranium mining and milling operatiors are to he
understood. Therefore, the following recommendations for addi-
tional studies include evaluations of the ambient radcn concen-
trations, radon progeny working level determinations, radiation
surveys, and airhornc paniculate measurements.
1. Source term identification in the Anbrosia I
should be completed. Included in these stui
he radon in effluent discharges from niillinj
tions, mine ventilation and ion exchange pi;
tions; and radon exhalation from ore stockpi
nines and nil Is, tailings ponds and piles,
uraniuE-bcaring formations.
In conjunction with the source term identification,
careful evaluation of the local area background radon
concentrations is necessary.
letter definition of area background conditions prior
to the initiation of active raining and/or milling
operations should be coiapleted for any proposed mining
or milling area so that pre-operational baseline
conditions can be established. Such areas include San
Wateo, Churchrock, and the area east of Moquino where
n mill and nine are under development.
Long-term sanpling jninisum of ono yearl to |determine
any seasonal variations and to allow annual averaging
for comparison to applicable Stato and Icderjal regula-
tions should be considered. The need for additional or
continuous environmental monitoring and/or revision of
discharge 1 inflations could then he based on these
ii.it a.
The ultimate goal of all the above environmental
studies should be a thorough evaluation of population
exposures due to uraniun Bluing nnd milling operations.
nkc region
ics should
opera-
nt opcra-
les at the
nd natural
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INTRODUCTION
At the request of tlic Sew Mexico l-nvironmental Improvement
Agency (NMEIA), through the U.S. Hnvironmcntal Protection: Agency-
Region VI, the Office of Radiation Programs - Las Vegas Facility
(ORP-LVF) conducted a survey during Xovembcr 1975 to evaluate the
ambient radiological air quality in the Ambrosia Lake arjsa of New
Mexico.
The Ambrosia Lake area is in the central part of thb exten-
sive (4,400 km'') Grants Mineral Belt. It contains three active
uranium mills, one inactive mill site, and numerous active under-
ground nines. Figure 1 shows the study area which includes the
cities of Grants and Milan on the cast, San Matco on the north,
and the villages of Blucwater and Thorcau on the west. This
study was designed to provide preliminary information on the
degree of airborne radiological contamination in the ent)ire
Ambrosia Lake area, rather than identifying specific sotfrce terms
and their resultant effects.
November was chosen as a month representative of wintertime
inversion conditions throughout the Ambrosia Lake regioiL It was
postulated that radon progeny working levels would be niiar
maximum values since the radon would be "trapped" under the
inversion layer allowing the radon progeny to achieve relatively
high equilib ium concentrations. Maximum indoor radon progeny
concentrations were also expected as a result of this inversion
layer source term coupled with the reduced indoor air ventilation
rate of the heating system versus the "open-air" cooling of
summert ime.
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#806
3.06
0.025?
UNITED
NUCLEAR
MILL
#805
0.36
0.0024
*
CORP.
Mateo
UNITED NUCLEAR
HOMESTAKE PARTNERS
MILL
Bluewater Q
* #801
D.79
0,0045
KILOMETERS
* Sampling
#805 Location
0,36 Average
OOOii Average
Location
Number
Radon Concentration
in pCi/l
inaoor woncmg Level
08OO *
1.21
0.0129
/
s Milan
FIGURE 1, GENERALIZED MAP OF SAMPLING LOCATIONS AND SUMMARY OF RESULTS
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TYPES OF SURVEYS
RADIATION SURVEYS
Radiation surveys, radioactivity in soils an
outdoor radon levels, indoor radon progeny concen
(expressed as working levels [WL]), and the outdo
particulate concentrations were measured during N
10 sampling locations (Figure 1) in the study are
ing report discusses only the results of the radi
radioactivity in soils, and the radon and radon p
trations determinations. The results of the airb
measurements are the subject of another report to
a later date.
Upon selection of a site as a suitable air s
tion, indoor and outdoor gamma radiation surveys
This survey was done to insure that the location
structed upon an area of elevated terrestrial rad
that some uranium ore or other radioactive raateri
present inside the structure. Such conditions co
the ambient outdoor radon levels and/or the indoo
determinations.
A pressurized ionization chamber (PIC)1 was
the radiation exposure rate (ER) in units of micr
hour (pR/h). The PIC is calibrated using a "shad
method employing a cobalt-60 source calibrated by
Bureau of Standards. The PIC is then inter-calib
to a radium-226 gamma spectrum. The PIC measures
and terrestrial gamma source exposure rates. All
ments were made at a height of one meter above gr
For the indoor measurements, the PIC detorminatio
about the center of the room in which the indoor [air sampler was
located.
yses, ambient
•ations
• airborne
ember 197S at
The follow-
ion surveys,
'geny concen-
ne particulate
e published at
mpling loca-
re completed.
as not con-
activity, or
was not
d have biased
working level
ed to measure
•oentgen per
- shield"
he National
ted to respond
oth the cosmic
'1C measure-
ind surface.
was made in
Radiation surveys were also made using a portable gamma
scintillator survey meter.2 This instrument was calibrated with
a radium-226 standard and measures the relative gamma radiation
exposure rate in units of pR/h. Table 1 presents the radiation
exposure rates measured at each location (indoor and outdoor) for
both types of detectors.
1. Reuter Stokes, Model RSS-111 Environmental Radiation Monitor.
2, Baird-Atomic, Type NE148A - Gamma Scintillator Ratemcter.
5
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Locatier
Code
800
801
802
803
804
815
806
807
808
810
TABLE 1.
Indoor
Radiation Level
foR/h 4t rants rl
Pressurized
lonization Chamber
16.0
13.0
17.5
16.0
13.0
16.5
29.0
15.0
17.5
no survey
Sctntillatnr
Survey Meter*
9
8
20
10
9
19
3Q
3
16
no survey
RADIATION SURVEYS
Outdoor
Radiation Level
(w R/h at 1 im?tprl
Pressurized
lonization Chamber
14.5
15.5
24.0
15.5
14.5
15.5
37.0
17.5
19.0
15.5
Seintlllator
Survey Meter*
9
3
30
10
11
19
45
10
18
10
Radium-226 Content
Top 5 on Sol 1
(pCi/g)
6.2
14.0
10.0
1.6
3.3
2.2
18.0
2.1
3.6
1.6**
* Gross values as measured with the field instrument.
•• Top 10 on of soil.
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Since the scintillator survey meter utilizes such s small
Nal crystal (lxl-1/2 inch) detector, its response is energy
dependent and, therefore, measurements made using this survey
meter should be "corrected" to the PIC exposure rates. This
correction factor has been derived from a least squares fit of
the regression line of the measurements of the PIC versiss the
scintillator survey meter (Table 1). Two correction expressions
have bee: obtained for the indoor and the outdoor measurements as
follows:
liR = 1.1S +2.5 (uR/h)
ER = 0.9S + 3.4 (uR/h)
Indoor Measurements
Outdoor Measurements
"S" is the meter reading of the scintillator survey metier and
"ER" is the corrected exposure rate based on the calibrated PIC
measurements.
In general, measurements by both types of detectoij indicate
that the indoor radiation levels are slightly lower than the
outdoor levels. This is the "housing factor" effect which
represents the gamma shielding characteristics of the structure
for both cosmic and terrestrial sources of radiation and includes
the contribution from the natural radioactivity of building
materials. The radiation levels at locations S802, 80(L and 808
appear to be slightly elevated compared to the other locations.
Considering locations =(800, 801, 80S, and 807 as representative
of normal background radiation conditions, the average indoor and
outdoor exposure rate (PIC measurement) was about 15 and 16 pR/h,
respectively. Therefore, the typical housing factor fpr these
background locations was 0.9.
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AMBIENT OUTDOOR RADON-222 CONCENTRATIONS
Sampling System and Analytical Methods
A continuous, low-volume sampling system was usejl to obtain
the ambient outdoor radon sample (U.S. Public Health Service,
1969]. This sampling technique consists of drawing filtered air
through a small, low-volume air pump (less than 10 ralfmin
sampling rate) into a 30-litir Mylar bag. The air intake was
about one meter above the ground surface. Usually a ;ontinuous
48-hour air sample was collected and analyzed for rad )n content.
Radon analysis was completed at a field laboratory using a
portable apparatus for sample preparation (Johns, 1975). This
system permits the transfer of the 48-hour ambient air sample
into a container of known volume, followed by circulation through
water and carbon dioxide traps. Radon is retained on
coal traps maintained at a temperature of about minus
dry ice and acetone. The sample is then de-emanated
scintillation cell using helium at 400°C, The Lucas
two char-
80°C using
into a Lucas
cell is held
for 4-1/2 hours to allow for the ingrowth of the radoln daughters
and then counted on a photoraultiplicr tube/sealer unit.
Table 2 summarizes the ambient outdoor radon
which are given in full in Tables B-l through B-9 (Apjpendix
All reported results are the measured ambient concentrations
have not been corrected for "background" radon levels
con|centrations
B).
and
Meteorological data obtained during this study o]re summa-
rized in Appendix C.
Geologic Influences on Radon Concentrations
The determination of typical radon background concentrations
for the Ambrosia Lake area is complicated by the difficulty of
specifically identifying the natural versus "man-induced" radon
source terms. Several geologic formations in the arfa average
from 0.05 to 0.25 percent uranium (Kottlowski, 1975) and provide
a naturally elevated radon source term. The multiplicity of
"man-induced" radon source terms (e.g., mill and ion exchange
plant effluent discharges, tailings ponds/piles, minis ventilation
exhausts, and ore storage piles) add to the ambient radon levels
in the area. The lack of adequate sampling locations due to the
non-availability of electrical power also hampers a sampling
scheme aimed at identifying specific radon source terms.
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TABLE 2. SUMMARY OF AMBIEHT OUTDOOR RADON-222 CONCENTRATIONS
AND INDOOR RADON PROGENY LEVELS
AMBIENT OUTDOOR
RADON-222 CONCENTRATION
(pCi/1)
Location
Code
800
801
802
803
804
805
806
807
808
810
Location
Description
Milan City Hall
Bluewater Village
Milan
Broadview Acres
Ambrosia Lake
Highway Junction
San Mateo
Ambrosia Lake
Post Office
Bluewater
Ambrosia Lake
Trailer Park
Maximum
2.7
2.8
4.9
3.6
3.4
0.90
5.4
1.8
6.6
0.14
Minimum
0.13
0.21
0.46
0.24
0.21
0.062
1.0
0.32
1.3
0.07
Average
1.2
0.79
2.2
2.1
1.9
0.36
3.1
1.1
3.6
INDOOR
RADON PROGENY
Average
Working
Level (WL)
0.0129
0.0045
0.0128
0.0271
0.0096
0.0024
0.0257
0.0077
0.0148
No <
Sampling
Time
(Hours)
687.3
328.1
697.0
628.5
296.9
620.5
615.0
586.1
486.5
iamfiJe
PERCENT
EQUILIBRIUM*
Percent
108
57
58
129
51
67
83
70
40
Percent equilibrium equals the working level value divided by the ambient radon concentration
divided by 100 pCi/1; since, one working level is equivalent to 1003 equilibrium of 100 pCi/1
radon and its progeny. (See discussion in text under INDOOR RADON PROGENY LEVELS.)
-------
The sampling locations used in the study were evaluated in
terras of geologic characteristics and orientation with respect to
mining and/or milling activities (Table 3). This nclped in
assessing whether background or man-induced elevatpd conditions
were present, and was prerequisite to realistic grouping of the
radon and radium data for statistical testing. Additional
background information concerning geologic conditions as related
to uranium occurrence and the terrestrial radon fljx are con-
tained in Appendix A.
kgrounl) and mining/
:ally, the
aver barren
The data were grouped into control (bac
milling area categories as shown in Table 4. fiasi
geologic settings considered consist of alluvium
(i.e., containing 0.1 percent or less uranium) sedimentary
basalt bedrock. The first comparison involved relatively
sequences (>50 feet) of alluvium over barren rock
second considered much thinner alluvium (<50 feet)
bedrock that probably was barren but may have contained
elevated levels of uranium.
Statistical testing was done using the Mann-Wiiitney test
(Mann and Whitney, 1947; Siegel, 1956) which enabl
of two independent sample sets (using ordinal measurement) to see
whether the samples are drawn from the same population. It is
one of the most powerful of the nonparamctric test
particularly useful when the inherent assumptions
metric tests cannot be satisfied. The power-efficiency of the
Mann-Whitney test approaches 95.5 percent of the most powerful
parametric test (the t test) as N, the number of observations,
increases. To employ the test, the radiochemical
or
thick
•fhereas the
underlain by
slightly
DS comparison
* and is
of the para-
data are put in
ascending order, assigned ranks and then the lattejr are grouped
according to whether they are from control or elcv
locations. The statistic
following formula:
U is calculated using ci
ated sampling
thcr of the
U = nin2
-K,
U = n.
Where
-R,
R. = sum of the ranks assigned to the group with sample
size n^
R2 - sum of the ranks assigned to the group with sample
size n2
Depending on the values of nj and n2, cither critical values of
U or probabilities associated with the observed U (ire used to
10
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TABLE 3, SUMMARY OF RADON AND RADIUM ANALYTICAL RESULTS AND
GEOLOGIC CHARACTERISTICS FOR SAMPLING LOCATIONS
Scplioz
320
S3!
XX
«}
33;
SOi
yA
307
=D«
310
*»..!-
an™
Si-winter
$BH? alii ares
it. 3 =1 E sf =$11)
ttlHP =111 area
(1.0 =1 SS» of all!)
tebresin Li&r
(.'tmstlrn of !."! 43
and 5W)
JSK !l»«*o
S=£r3Sl» !,«•>».
(1.3 at !E of terr-
Ar«a?t?r,da Co. ffllll
area ( 1.6 Ri 3E
of alll)
fcstrtssiq Lak«
(1.1 cl EE of
terr-ifclre nillj
Ihoraa-a ai*& (7,3
si 3i 'sr Tbsr^aa)
In Air
pCl/1
1.2
o.n
, -,
j i
1.9
0.3h
3.1
1.1
3.6
0.11
Hltdlusi In Trfill
(Top "i as)
(>, 2
1^
11
1.6
3.3
.?..«
1?
2.1
3.6
1.6*
Cubnlritlt;
Wluvliffl
AiluvJvra
Alluvlua
AJl-artiBi
dHuvliBl
Alluvlus
Rll-rdun
Bnsnlt
Flow
Alluviua
Alluriui
n..lc«lc CuMlltoni
Esttisstfcrt
Till ekness
i.?i
•>•)
'jO-71
11-7i
jn
30
40
»
30
10-53
UniiBrlnln
Int«»rbedded basalt
flows 4Ch!ii!e Fb.
Sun Andrei
UiwaioM
Chlnle fcraaticn
Qilnl* >onaatior.
VfstwttttT Canyon
y^nb*?r
Point Lcokot.'.
SimdstDtiP 1 *4ene-
f#* Famailon
llan-oi Shtle
Al 1 'JVi ITS
Uoncoa Shale
Dakota Sandstone
-^.aet^hale
^H.
Background; geologic ecmdltlcaiF broadly
similar I* staUona 301, 802, £03, 807
SacK** rounds geclo^lc renditions broadly
cio**or to stations 330, 3QJ, 803, ^^
Elevated radon due to aillifig?
Elevated r^dar, due tc ollling?
Possibly miturally high radon
Backgrounds e^cloc^s eor.ai t! w.s sJsillar
to ftfctlaui 306, 307, 303; KD tnllinga;
rlais&s* slrte venlllatJ^i 3 ffiii*a ,'W;
niir.Inal «h«fi vontilatlm locally
Elevated radon dye to clr-ing, allliry^?
lllne ventMatton exhaust nesrty.
Elevalad rad^s due to allllng?
Elevated radsra due to dning, milling?
Ulr* ventilation eihausi nearby.
Background; geologic condl titans islailar
to atCtlons 306, SOflj no zint ventils-
Tcp 10 t
-------
TABLE 4. COMPARISON OF AVERAGE RADIUM
Geologic
Setting
Thick alluvium or basalt/
underlain by barren rock
Thin alluvium/
underlain by barren (?) rock
Control
(Background)
Radium Radon
(PCI/1) (DC1/1)
6.2 1.2
14.0 0.79
2.1 1.1
2.2 0.36
1.6 0.11
AND RApON DATfl
Locations
Considered
800
802
801
803
807
804
805
806
810
808
Elevated
(Mining/Milling Areas)
Radium Radon
(pCi/1) (pCi/1)
18
1.6
3.3
18.0
3.6
2.2
2.1
1.9
3.1
3.C
-------
accept or reject the null hypothesis at the preset level for
alpha, usually 0.05 or 0.01.
Radon concentrations in background locations and in the
areas of active mining and milling were considered using 125
individual field measurements of ambient air quality (Taales B-l
through B-9) and averages of these data (Table 4). In bjth cases
the data were separated into control (background) and el?vated
categories according to the breakdown in Table 4 and on the basis
of the information shown in Table 3,
Using the averaged radon data for the five control stations
(#800, 801, 805, 807, 810) and five stations in areas of active
mining and milling (1802, 803, 804, 806, 808), a two-tailed test
at the five percent level of significance indicates significant
difference in ambient radon concentrations between sampling
points. Khen actual individual data versus averaged values are
compared, the degrees of freedom (number of observations minus
one) increase from 9 to 124 and thereby increases the strength of
the test. In this instance, and again using a two-tailed test,
there is a statistically significant difference in rador concen-
trations between the two types of sampling points at the one
percent level of significance. In short, ambient radon in air is
significantly greater in areas of active mining and mil]ing than
in areas considered to be background.
Results
At San Mateo (Location *805), ambient outdoor radon concen-
trations ranged from 0.06 to 0.90 pCi/1 (Table B-6). Tlie average
concentration was 0.36 pCi/1, with a standard deviation of 0.21
pC.i/1. These results are comparable to radon levels measured at
three locations in the vicinity of San Mateo during sampling
periods extending from September 1972 to August 1973 (Ni?w Mexico
Environmental Institute, 1974). Measured at three feet above
ground surface, radon concentrations ranged from 0.008 ;o 0.91
pCi/1, with an overall mean of 0.19 pCi/1 for the eight-month
sampling program. The statistical error in counting anfi sampling
has a standard deviation of ±12 percent (i.e., 0.19 - Oi,04 pCi/1,
at the 95 percent confidence level).
The village of San Mateo is underlain by the Point Lookout
Sandstone and Menefee Formation, neither of which is ore bearing.
Beneath these are the Gallup Sandstone and Crevasse Canyon Forma-
tions. All four units probably contain 0,05 percent or less
uranium. During the November 1975 study, ventilation of the
nearby mine shaft may have slightly elevated the ambient radon
levels. However, since the shaft was only advanced to a depth of
500 feet, and the target ore body is at a depth of 3,000 to 4,000
feet, significant radon from a single vertical shaft without uny
lateral drifts is believed to be minimal. The monthly average
ambient radon concentration of 0.36 * 0.42 pCi/1 for this study
is about twice the previously reported determinations made prior
13
-------
to shaft sinking and extending over a longer time period (i.e.,
mean of 0.19 pCi/1 for the 1974 report). Both results arc
believed to be representative of local background r idon levels
prior to extensive raining or uranium mill operation}, but the
increase in 1975 relative to 1974 suggests that additional data
are necessary to adequately define annual variation
Durjng November 1975, the monthly average ambi
concentration at location »801 in Bluewater Village
0.79 ± 1.2 pCi/1 (Table B-2). Geologic conditions
consist of several hundred feet of saturated alluvi
by carbonate and clastic bedrock essentially devoid
i.e., less than 0.05 percent uranium. In addition,
Village is about two miles upwind of the Anaconda
and assrciated tailings pond; therefore, the measur
levels it this location arc believed to be rcprcsen
local natural background conditions.
Location *807, a private residence about 1.6 TO
of the Anaconda Company mill, is located in an area
by very thin alluvium underlain by a basalt flow (b
monthly average radon level was 1.1 J 1.0 pCi/1 (Tabl
:nt radon
was
it this site
jra underlain
of uranium;
31ucwater
Csmpany mill
»d radon
tative of
les southeast
characterized
edrock). The
e B-8).
Although Thorcau (Location «810) is at the mouth of a valley
similar to the Ambrosia Lake Valley, the sampling location was
topographically and stratigraphically below exposures of the
Westwater Canyon Member of the Morrison Formation, the principal
ore-bearing unit in the Grants Mineral Belt. Thcrejforc, the
average radon content (0.11 pCi/1) is probably Icssj than the
background radon level in the Ambrosia Lake area.
Until additional studies arc completed to better define
radon background conditions in the Ambrosia Lake a
estimate of background radon concentrations may be
ea, the best
obtained by
These five
considering locations '800, 801, 805, 807, and 810
locations arc somewhat removed (at least one mile distant) from
the immediate vicinity of any uranium mill or activic mining
operation, and are not in close vertical or lateral
the uranium-bearing formations. In November 1975,
concentration for these five "background" locations
pCi/1, with a standard error of 0.21 pCi/1.
proximity to
the mean radon
was 0.72
Two sampling locations (*S02 and 803) were established in
the vicinity of the United Xuclcar-IIoracstake Partners (UNHP) «nill
and tailings pond complex. Location #802 is within 200 yards and
directly cast of the UNI IP complex and had a monthly average radon
concentration of 2.2 pCi/1 (Table B-3). Location «803 (Table
B-4) is about one mile south-southwest of UMIP and averaged 2.1
pCi/1 radon for Movembcr 1975. The area surrounding the UNHP
complex is underlain by approximately 100 feet of alluvium (half
of which is saturated) which overlies the Chinle Formation.
Neither unit is considered ore bearing at any location in the
Grants Mineral Belt because of the low uranium content (probably
1-1
-------
below 0.05 percent). Radon diffusion is also! expected to be
minimal due to the overlying, near-surface ground water which
inhibits radon diffusion. The average monthly radon levels of
2.1 and 2.2 nCi/1 for the two sampling locations in the vicinity
of the UNHP complex appear to he in excess of natural background
concentrations and indicate that the active rail! complex is
apparently the source of elevated radon concentrations.
Location *S04 is at the junction of ,Sta
53, about five miles east-southeast of the K
Ambrosia Lake area. Although this location
mines and mills, the elevated radon level of
B-5) may be influenced by nearby outcrops of
Member, the principal ore-bearing unit in th
This station was regarded as elevated dcspit
active mines and mills. (For purposes of st
of "background" versus "elevated" conditions
conservative in that the radon and radium co
location are slightly lower than the other e
e highways 509 and
rr-Mcdeo mill in the
downwind from the
1.9 pCi/1 (Table
the h'cstwatcr Canyon
Ambrosia Lake area.
the distance from
itistical comparison
this decision is
centrations for this
evated locations.)
The highest radon concentrations in ambient air were mea-
sured in the Ambrosia Lake area where there is an active mill,
numerous active mines, and an inactive mill and associated
tailings pile. l-"or location »806, the highest radon level was
5.4 pCi/1 (Table B-7), with an average of 3.1 pCi/1 for November
1975. The highest radon concentration measured at any of the
sampling locations Kas 6.6 pCi/1, with a monthly average of 3.6
pCi/1 (Table B-9) at location "80S. Both ideations arc nearby
mine ventilation exhaust ducts and these results indicate that
elevated radon levels also occur in the vicinity of the active
uranium raining and milling operations in the) Ambrosia Lake area.
-------
RADIUM IN SOIL
Soil samples were also collected at each a
location. Tlie results of analyses for radium-2
reported in Table 1. Inch soil sample was obta
spot as were the outdoor radiation measurements
sampling procedure, which utilized a steel scoo
100-cm2 in surface area, was established to obi
soil sample of 500 cm1, representing activity i
centimeters of soil. The highest concentration
soil (18 pCi/g) was at locations S806 and 802,
in close proximity to active uranium milling op
elevated radium levels probably represent windb
ore dust in addition to the naturally occurring
levels measured at the other sampling locations
high radium-226 content of 14 pCi/g at location
to explain, but may be due to a natural tcrrcst
Radiation levels at location «S01 do not appear
compared to the levels measured at the other tv>
the higher radium in soil contents. Further di
uranium content of soil and rock materials in t
contained in Appendix A.
The Mann-l.h i tncy test was also used to com
soil data as shown in Table 4, Although the av
content in the raining and milling areas is 8.9
pCi/g in the background samples, the difference
cant at the five percent level of significance.
limited data, this suggests that radium in loco
probably not the principal influence on elevate
concentrations and that other mining/milling-rc
of greater importance. [
r sampling
6 content arc
ncd at the same
A standardized
, 5-era deep and
in a standard
the top five
of radium-226 in
oth of which arc
rations. These
own tailings or
terrestrial
The unusually
"801 is difficult
ial anomaly.
to be elevated
locations with
cuss ion of the
c study area is
arc the radium in
rage radium
Ci/g versus 5.2
is not signifi-
Hcspite the
soils is
airborne radon
ated factors are
Radium concentrations in the upper five centimeters of soil
(Table 4) average 8.9 pCi/g at five locations ("802, 803, 804,
806, 80S), all of which are within 0*5 to 2 miles (average 1.2
miles) of active uraniun nills and associated tailings. Elevated
levels relative to background locations may be a result of
windblown tailings, although it is unlikely that the high radium
(14 pCi/g) in soil at Bluewatcr (Location "801} can be attributed
to the nearby Anaconda Company mill because the prevailing wind
direction is from the north to northwest. The alluvium in the
Bluewatcr area is expected to be low in radium, i.e., 1 to 3
pCi/g or less. At location *807, which Is 1.6 miles southeast
and therefore downwind of the Anaconda Mill site, radium is only
Z.I pCi/g, or essentially equal to that in the background samples
from Thorcau (Location «81Q, 1.6 pCi/g) or San Mntco (Location
»805, 1.2 pCi/g).
16
-------
Radium concentrations in the vicinity of the
from 1.6 to 18 pCi/g. Although the prevailing winds are from the
north to northwest, windblown tailings have been observed in the
trailer court 0.3 miles east of the mill (Location
could account for the elevated levels (18 pCi/e) compared to
location ''803 which is downwind, but a mile away a;
representative in that the soil sample was taken f
INHP mill range
»802). This
id possibly not
rom a corral
jy stock,
for the
which was an
actively plowed and irrigated field 1.6 miles southeast of the
Anaconda Company* mill.
area where Tine materials may have been scattered
Similarly, distance and soil reworking may accouni
relatively low value of 2.1 pCi/g at location ~
In Ambrosia Lake, radium content of surficiai
highly variable, ranging from 3.3 to 18 pCi/g. Tl
concentration is 1.3 miles northeast of the
Therefore, it appears that radium conccntrati
ficial soils adjacent to active mining and milling
not readily correlate with known sources of radiun
wind data. Local weather conditions, particularly
direction, winnowing or mixing processes associated with human
activities, and influences fron other local source
trucks and other heavy equipment associated with n
may contribute to the observed high degree of vari
clear though that bad.Around locations {?800, 805
uniformly low (average radiu.-:
locations near active mills e.g.
radium » 13.2 pCi/g).
Discussion
as cor
soils is also
c highest
cGee mill.
ons in sur-
opcrations do
and available
wind speed and
fS02, 806, and
108 (average
In summary, examination of the radon data inJicatcs that
radon concentrations in air in the Ambrosia Lake
vicinity of the Anaconda Conpany and UNHP mills a
elevated relative to locations in Hlucwatcr, San
Milan. Identification of specific source terms (
versus man-induced) cannot he resolved with data
such as ore
ining/ini] ling
ibility. It is
810} arc
pared to those
.irea and in the
re statistically
latco, and
i.e.
natural
from the present
study. Although elevated radon concentratons may be attributable
to the relative abundance of uranium-bearing bedrock in the
Ambrosia Lake area, the radium in soil data suggest that the
principal influences arc raan-induced radon originating in the
tailings piles, aill and sine exhausts,, or ore stockpiles.
Current Federal and State of Now Mexico regulations for the
nuclear industry are shoxn in Table 5. Insofar as these regula-
tions permit annual averaging of concentrations for compliance
monitoring purposes, and considering the fact that all samples
were collected in unrestricted areas occupied by the general
population, it is reasonable to apply the population guide of
one-third the 168-hour value (i.e., 1 pCi/1 radon) for radon
sources covered in the regulations. The dose equivalent from the
continuous exposure to the regulatory limit of 3 pCi/1 for radon
17
-------
(under equilibrium conditions similar to those of living accommo-
dations with normal ventilation) is estimated to be 12 rem p
-------
Several other situations exist which should be evaluated
with respect to minimizing radiation exposure risks to
tions in mining/milling areas. A mine ventilation exhsiust duct
typical of those scattered throughout the Ambrosia Lako area is
shown in Figure 2. Perhaps a vertical exhaust discharge arrange-
ment, as opposed to the horizontal discharge shown in Figure 2,
would provide additional dilution of exhaust gases containing
elevated concentrations of radon and radon progeny. In order to
minimize population exposures, a populated zone restriction
should be considered for active raining areas and engineering
planning could also be formulated to locate mine exhaust ducts in
areas which would not affect the air quality of exist! ig popu-
lated areas.
Due to the extensive development of underground m ning in
the Ambrosia Lake area, land surface subsidence has occurred in
several areas. The use o£ mine overburden or uranium ore mate-
rials as landfill in such areas, as shown in Figure 3, provides
another source term for increasing radon levels. It is suggested
that appropriate radiological surveys be conducted to assure
public health and safety prior to any use of mine oveiburden,
mine ore, or tailings material in reclaiming land; paiticularly
if the land is to be used for construction of housing r other
structures.
popula-
19
-------
iM&CTwn-"4""
!y
^•-fc
Wife''
M
*
,%M^?W»«TOaV
..XrtV^"''^ "-•" "•*"'
<»«SVK- " '
FIGURE 2, TYPICAL MINE VENTILATION EXHAUST I1UCT
• *;*'
,^j«*v
FIGURE 3. MINE OVERBURDEN OR ORE MATERIALS USED AS LANDFILL
20
-------
INDOOR RADON PROGENY LEVELS
Sampling System and Analytical Methods
The indoor radon progeny levels were measured using ja Type
II, TLD-Radon Progeny Integrating Sampling Unit (RPISU)
(Schiager, 1971). This sampling unit uses thermoluminesdent
dosimeter disks (TLD) to absorb the alpha particle emissions from
the radon progeny collected on a membrane filter through (which
the sampled air has passed.
The measurement of stored energy in the exposed TLD(disk is
obtained with a Harshaw Model 2000-TLD reader. The reader gives
a readout in nanocoulombs which is converted to a working level
(WL) value by utilizing a working level-liter per nanocojilomb
(WL-l/nC) conversion factor which is obtained through calibration
tests in known radon progeny atmospheres. All WL determinations
were completed at the Las Vegas facility of ORP.
Results and Discussion
The average ambient indoor radon progeny levels for! November
1975 are presented in Table 2 and shown in Figure 1. All sample
results (i.e., ambient values uncorrected for background level)
for each sampling location are contained in Tables D-l tjhrough
D-9, Appendix D.
Current Nuclear Regulatory Commission regulations ((January,
1976) limit radon progeny levels to 0.03 working levels (above
natural background) for continuous exposure in unrestricted areas
(Table 5). Another guideline for continuous exposure to indoor
radon progeny concentrations was established by the U.S. Surgeon
General in 1970. These guides were promulgated as a result of
the health hazard evaluation of the use of uranium mill tailings
material for construction purposes. These guides provide reme-
dial action recommendations for three ranges of working level
values above natural background. In summary, for locations with
WL values less than 0.01 WL, no remedial action is recommended.
Por sites exceeding O.OS WL, remedial action to reduce WL expo-
sure is indicated. For the range 0.01 to O.OS WL, the need for
any remedial action may be suggested after due consideration of
all exposure routes and cost estimates of remedial action alter-
natives. These Surgeon General Guidelines have effectively been
applied to the Grand Junction, Colorado remedial action program
for structures incorporating tailings material. The natural
background WL value for the Grand Junction area was determined to
be 0,004 WL (Joint Committee on Atomic Energy, 1971),
21
-------
During this study, sampling difficulties were encountered at
several indoor locations (e.g., SS01 and 804) which had wqod or
coal burning fireplaces, cigarette smokers, or excessive c^ust
created by nearby vehicular traffic. Such atmospheres were
characterized by excessive airborne particulate natter which
caused the TLD air sampler to shut off due to excessive dtst
loading of the membrane filter. Decause of this, minimum sample
volumes were obtained for locations S8C1 and 804 (Tables E-Z and
D-5, respectively); hence, there may be large error terms in
these reported determinations.
Considering locations 0800, 801, 805, and 807 as repiesenta-
tive of "background" locations, the mean working level determina-
tions was 0.0069 WL, with a standard error of 0.0046 WL. These
indoor radon progeny working level determinations are consistent
with the outdoor ambient radon concentration results (Table 1).
Both evaluations show the same trend of elevated levels ir the
vicinity of uranium mills or active mining operations, as in the
Ambrosia Lake area.
Assuming that the indoor radon concentration would be
to the measured ambient outdoor concentration, the percent
equilibrium of radon and its progeny may be calculated. These
results are shown in Table 1. The calculated percentage equili-
brium for locations 1/800 and 803 exceed 100 percent and signifies
that it is erroneous to assume that the indoor radon leve} is
loca-
equal to the measured outdoor concentration for these two
tions. That is, for locations f/800 and 803, the indoor rjjdon
levels are probably in excess of 1.2 and 2.1 pCi/1, respec
equal
tively.
The percent equilibrium for all other sampling locations langes
from 41 percent to 83 percent, with an average equilibriun
percentage of &1 percent. Such hig!. equilibrium values ai
indicative of the low air exchange rates for the season (5,.e.,
wintertime when doors and windows are not open) , and the type of
passive heating systems of the structures (i.e., wood or coal
burning fireplaces rather than forced air heating systems with
filtration).
An initial screening survey, during the week of June 11-17,
1974, measured the indoor radon progeny working levels in two
private residences directly east of the IMiP mill site. One
location had 0.0282 WL for the 144.1-hour sampling period. The
second location (0802) had a value of 0.0100 WL for the
144.9-hour sampling period. For the November 1975 study, the
average ambient radon progeny working level for location ?802 was
0.0128 WL (Table D-3). Although the November value is slightly
higher than the June level at location $802, no definite conclu-
sion can be made regarding seasonal variations of radon progeny.
Therefore, it is recommended that additional long-term evalua-
tions of the indoor radon progeny working level bo undertaken for
selected locations in the vicinity of mining and milling opera-
tions .
22
-------
Rl-FERENCES
Ahrens, L, H. , Frank Press, Kalervo Rankama, and S. K. Huncorn
[1959). The geochemistry of thorium and uranium, Physiqs and
Chemistry of the Earth. 3, Pcrgamon Press, p 298-348.
Bachman, George 0., James D. Vine, D. Jones, Charles B. [Read, and
George W. Moore (1959). Uranium-bearing Coal and Carbonaceous
Shale in the La Ventana McTsaArea, Sandoval County, New[Mexico:
U~.S. fieol. Survey Bull. 1055, p 295-307.
Chapman, Wood, and Griswold, Inc. (1974). Geologic Map I of Grants
UraniumRegion: New Mexico Bureau of Mines andMineral' Resources,
Geologic Map 31, Three sheets. '
Johns, F. B., ed. (1975). Handbook of Radiocheiiiical Anklytical
Methods, U.S. linvironmentalTrotection Agency , EPA-6507JJ-75-001.
Joint Committee on Atomic Energy (1971). Hearings on tpe Use of
Uranium Mill Tailings for Construction Purposes.
Printing Office, Washington, D.C., 515 pp.
U.S, Government
Kittel, Dale F. , Vincent C. Kelley, and Paul li. Mclancojn, (1967).
Uranium deposits of the Grants region, Guidebook of Defiian.ce--
Zuni - - Mt. Toy1or Reg i on - Arizona and NewTlex Jco: "Ne\7 Nlo'^i c o
Geological Society 18th FlellConference, p 175-183.
Kottlowski, F. (1975). New Mexico Bureau of Mines. Telephone
communication with R. Kaufmann, November 25, 1975.
Mann, H. B., and D. R. Whitney (1947). On a test of whether one
of two random samples is stochastically larger than tht? other:
Annals Mathematical Statistics, Vol. 18, p 52-54.
New Mexico Bureau of Mines and Mineral Resources, (1963).
Geology and Technology of the Grants Uranium Region: State
Bureau of Mines and Mineral Resources, Memoir 15, 277 pp.
New Mexico Environmental Institute (1974), An Environmental
Baseline Study of the Mount Taylor Projoct Area ofNew Mexico,
prepared for the Gulf Mineral Resources Company.
Rogers, J. J. SV, and J. A. S, Adorns (1957), Autoradiography of
volcanic rocks of Mount Jassen: Science, Vol. 125, p 1150.
23
-------
Schiager, K. J. (1971). The Evaluation of Radon Prog ny Exposures
in Buildings: A Report on Equipment and Techniques^
State University"! Department of Radiology and Radiat
Fort Collins, Colorado.
Siegel, S. (1956). Nqnparametrie Stati sties for the
Sciences : McCr aw - Hi 1 ITBooTc CoT 7" New YorlT, 312 pp.
Swift, J. J., J. M. Hardin, and H. K. Galley (1976).
Radiological Impact of Airborne Releases and Direct
i\civi j. u ±. v^ A.V, u x AHipm-i. u A MJ.IUUAIIC; i\i^±cu^c^ auu LJJ.I\J^L
Radiation to Individuals Living Near Inactive Uraniu
Tailings Piles. U.S. Environmental Protection Agenc
EPA-S20/1-76-001.
Trauger, Frederick D., ed. (1967).
Guidebook of Def
New riexic
Mt. Taylor Region Arizona and New Mexico;
Society, Guidebook, CighteentB Field Conference, 228
U.S. Navy (1969).
Part 2.
World-Wide Airfield Summaries, Vo
U.S. Public Health Service (1969). Evaluation of Ra
Uranium Tailings Piles, DER 69-1. U.S. Department 0
Education, and Welfare, Uockville, Maryland.
U.S. Surgeon General (1970). Recommendations of act
radiation exposure levels in dwellings constructed o
uranium mill tailings, Hearings on the Use ofUraniu
Tailings for Construction Purposes, Joint Committee
Energy (1971) , p 51-54.
Colorado
on Hiology,
Behavioral
Potential
arama
TlTTl
ance-Zuni--
Goological
pp.
VIII,
on-222 Near
Health,
on for
or with
Mill
n Atomic
24
-------
APPENDIX A
GEOLOGIC FACTORS AFFECTING ATMOSPHERIC RADON
The Grants Mining District, which includes the Ambrosii
area, is one of three active districts in the Grants Mineral
Belt. Other districts of importance are located north of Li
about 27 miles to the east, and Churchrock, located 33 mile;
west-northwest. Relatively inactive districts are located
19-24 miles west in the Mariano Lake-Smith Lake areas, altln
there has been no significant production to date.
Lake
cuna.
bout
ugh
im-
au of
is
in,
s'CSt
Geologic conditions in the Grants Mineral Belt, particularly
as they relate to the occurrence of uranium deposits, are s
marizcd in reports by Trauger (1967) and the New Mexico Bur
Mines and Mineral Resources (1963). The Grants Mineral Bel
flanked on the north and northeast sides by the San Juan Ba
on the cast by the Rio Grande trough, and on the south and
by the Acoma sag and the Zuni uplift. Exposed sedimentary rocks
in the area range in age from Pennsylvanian to Cretaceous and
rest on Precambrian gneiss, schist, and granite exposed in the
core of the Zuni uplift. Intrusive and extrusive rocks of the
Mount Taylor and Zuni volcanic fields arc of Tertiary and
Quaternary ages. The regional dip of the sedimentary rocks is
northward to northeastward, the latter direction prevailing in
the Ambrosia Lake-Grants mining district. Arcally, the mos
extensive units in the Grants District consist of limestone,
shale, sandstone, and basalt flows (sec Figure A-l).
Differential erosion has crcafd a series of northwest-
trending escarpments generally capped by thick-to-massivcly-
bcdded sandstone and underlain by less resistant shale and
thin-bedded sandstone. In the area surrounding Grants-Bluciwatcr
and Ambrosia Lake, mesas arc formed where crosional remnants of
the escarpments arc covered by lava which is extremely resistant
to weathering. Extensive basalt flows of Tertiary and Quaternary
age originated in the Zuni Mountains to the south, in Mount:
Taylor to the east, ;ind in a volcanic cone known ns HI Tintero
[the inkwell) located five miles north-northeast of Hluewntcr.
Not shown in Figure A-l is the alluvium which floors the prin-
cipal valleys and is thickest (average 100-300 feet) in Uliieuatcr
Valley extending from Blucwatcr to Grants. The alluvium i»
absent on the crcst.s and steep sides of the mesas and escarp-
ments. A relatively thin covering (overage = <10 feet or loss) is
believed present in the central portions of the Ambrosin Luke
area and at the toe of steep slopes forming the northern ntul
eastern boundaries,
25
-------
LEGEND
GEOLOGIC UNITS
161 N» STMUl UIIT
ALLUVIUM
ouiroun
nituiT
ciutcioin
JIUilK
must
HWUI
NtUHMHU
m
m
VOLCANIC ROCKS. UNDIFFERENTIATED
POINT LOOKOUT SANDSTONE & MENEFEE FORMATION
GALLUP SANDSTONE & CREVASSE CANYON FORMATION
DAKOTA SANDSTONE & LOWER MANGOS SHALE
MORRISON FORMATION-WESTWATER CANYON MEMBER
JURASSIC STRATA BENEATH MORRISON FORMATION
CHINLE FORMATION & WINGATE SANDSTONE
PERMIAN STRATA. UNDIFFERENTIATED
PRECAMBRIAN ROCKS. UNDIFFERENTIATED
MISCELLANEOUS
GEOLOGIC UNIT CONTACT
SHAFTS
URANIUM MINE
URANIUM MILL
SETTLEMENTS/TOWNS
URANIUM MINERALIZATION
AT OR NEAR LAND SURFACE
AIR SAMPLING STATION
-------
FIGURE A-1. GEOLOGIC MAP OF THE AMBROSIA LAKE MINING DISTRICT AND VICINITY
(Adapted from Chapman, Mood, and Griswold, Inc. 1974)
-------
URANIUM OCCURRONCIi
Several uranium-bearing
Mineral Belt region along the
on the flanks of major north-
the escarpments by ephemeral
feet, the uranium content of
averages 0.25 percent and is
the surface or outcrop, this
uranium whereas other bedrock
than 0.05 percent uranium.
formations crop out in
east-west trending cs
south trending valleys
streams. At depths of
the Morrison formation
therefore of commercial
formation averages abo.it
formations usually contain
Uranium mineralization in the Grants Mineral B
greatly depending on tlie particular geologic unit(s
the depth of burial, and subtle but highly sclcctiv
enrichment processes. The latter involve multiple
cycles, regional uplift and erosion, unique palcohy
conditions and geochemical factors, chief of which
organic substances in the clastic sediments and chcnically
reducing conditions. For all practical purposes, marked occur-
rence of ore, i.e., rock having a minimum average u
of 0.25 percent, is limited to the Kcstwator Canyon
Morrison Formation. Furthermore, ore in this unit
occurs at depths of several hundred feet or more an3 is probably
related to a reducing environment associated with t
of the regional ground-water table. Closer to the
Wcstwater Canyon Member, oxidizing conditions and a
processes have largely removed any uranium that may
present. Hxceptions to this rule arc found in shal
deposits in the Poison Canyon area, immediately sou
Lake, which arc associated with the lintrada Sandstone or lime-
stones of the Todilto Formation. Similar deposits
Butte were the basis for the first ore discovery in
the Grants
;arpments and
incised into
700 to 4,000
locally
value. At
0.1 percent
less
;lt varies
I considered,
s natural
•leathering
Jrological
lire entrapped
rainum content
Member of the
generally
ic occurrence
autcrop of the
ctivc leaching
have been
OK uranium
th of Ambrosia
n liny-stack
the region in
the early 1950's. Oxidizing conditions and leachinb, plus the
fact that many of the source rocks contain average pr below
average uranium concentrations, result in depleted levels of
uranium in alluvial sediments relative to sedimentary bedrock.
Uranium ore has been produced from various units including
the lintrada Sandstone, Todilto Limestone, Suimncrvillc Formation,
Bluff Sandstone, Morris ion Formation, and the I'akotJi Sandstone.
The aggregate thickness of the ore-bearing units is 1,000 to
1,500 feet. The Morrision Formation has yielded about 04 percent
of the ore and probably contains over 95 percent of the reserves
(Kittel ct al., 1967),
Sedimentary bedrock units containing low to intermediate
concentrations of uranium include the Cretaceous strata (Gallup
Sandstone, Crevasse Canyon Formation, Mancos Shale, Point Lookout
Sandstone, Mcncfcc Formation), and the .Jurassic Morrison Forma-
tion (exclusive of the Kesiwatcr Canyon Member). Studies of
uranium content in the Dakota Sandstone, Mnncon Slnilc, and Point
Lookout Sandstone exposed in the l.n Vcntaiin area some OS mil OH
-------
east of Ambrosia Lake were made by Bachraan et al. (1959). They
observed beds of coal, carbonaceous shale, and carbonaceous
sandstone containing a maximum of 0.62 percent uranium. The
average content in the "high grade" zones was 0.1 percent and
much larger areas contained between 0.01 and 0.10 percent.
Although conditions may be different in the Ambrosia Lajce area,
these analytical results give some credence to the 0.01
level selected for uranium in nonmineralized strata.
percent
Uranium concentrations in 10 samples of carbonaceous shale
collected in the summer of 1975 from the La Ventana mesa area
averaged 0.69 pCi/g uranium and from 0.79 to 4.2 pCi/g of radium-
226. This is essentially background for any area and ip evidence
that at least the Menefee Formation is not a significant source
of abnormal amounts of radon. This may also be true of the
remaining Cretaceous strata beneath the Menefee.
Units of Pennsylvanian through Triassic age are pvobably of
average or below average uranium content relative to tile average
for crustal rocks. These units include the Abo, Yeso, Glorieta,
and San Andres formations which arc present south of and beneath
Bluewater Valley. The Chinle Formation (Triassic) which is also
believed to be in this category, is exposed from just north of
the Anaconda Company mill to the base of the escarpment forming
the southwestern rim of the depression containing the Ambrosia
Lake mining district (see Figure A-l). The basaltic lava flows
present in the Blucwatcr, Milan, and San Mateo areas arc also
believed to be low in uranium content. Rogers and Adams (1957)
and Ahrens et al., eds. (1959) report that the uranium content of
basic extrusive rocks (basalts and andcsites) is on the order of
0.2 to 0.4 ppm (0.00002 to 0.00004 percent) and rathen evenly
distributed among the various constituents. Initial estimates of
radon release from formations in the Ambrosia Lake area indicated
that natural sources could possibly account for the radon concen-
trations observed during this study. However, there arc numerous
assumptions in these calculations including diffusion rates,
exposed surface areas for the various geologic units, and the
influences of dilution (mixing) in ambient air. Differences in
radon concentration among the various air sampling stations, some
of which can be regarded as controls (background), suggest that
local variations in geologic and other natural factor;! arc of
secondary importance compared to the influences from ruining and
milling operation.*;.
In addition to the uranium content of .soil/rock (and assum-
ing radium is present in equilibrium concentrations), ground-
water and soil moisture conditions significantly influence the
diffusion rate for radon. The study area has a serai-arid climate
characterised by about 10 inches of annual precipitation, and,
except for a relatively small part of the area cast of Grunts,
ground water is at least 50 feet below the land surface. There-
fore, radium content of the soils and soil moisture arc believed
to be the principal factors affecting the diffusion of radon from
purely natural sources.
29
-------
APPENDIX B
u
o
TABLE B-l.
AMBIENT OUTDOOR RADON-222 CONCENTRATIONS
LOCATION I80Q-M1LAN CITY HALL
TABLE B-2.
AMBIENT OUTDOOR RADON-222 CONCENTRATIONS
LOCATION I8Q1-BLUEWATER VILLAGE
'l~- TiW-
" 4-"1-. ll/i/75
I ( OHIO
it « *« \\ntn
>*• !%«
• » v it/am
* » •• u/io/n
H '» •*. 1IM7/74
*« rim
"-V "ini""
" .;; ll^7s
"it." "ST
'I5- 9-05
" 1850
* "« « 11/28/75
"•" 0713
'» aess '
"'^ "'naC?
iurjMrj
):/i,'?S 12/5/75
••tfon-ZZZ
2.7
J.I
l.»
9.W
o,4il
1.1
J. 3
Kl
S.5Q
6-Sf
1.2
1.1?
0.1*
0.11
2.1
1,2
(1% Staples)
Two Stgma trror Term
PCI/1
0.1S 1
1.13
a. 11
0.08
o.ot
(l.t'l
O.I)
0.11
B.Of,
0.06
0.11)
0.05
0.03
O.CK
0.13
1.7
On
Date
Tine
11/4/75
1125
11/5/75
oano
11/7/75
1045
11/9/75
1109
11/13/75
0955
11/15/75
1002
11/17/75
1025
11/19/75
1040
11/21/75
1035
I1/23/7S
0931
11/25/75
1 1035
11/27/75
0940
11/29/75
1210
If/ i/ rt
1210
Suaptary
11/4/75
Off
Dale
Tin*
11/5/75
0750
11/7/75
1040
11/9/75
1108
11/12/75
1630
11/15/75
1000
11/17/75
102S
11/19/75
1038
11/21/75
1035
11/23/75
0932
11/25/75
1030
1 1/27/75
0935
11/29/75
1205
12/1/7-,
1205
Iff err j
1505
12/2/75
ftadon-222
BC1/1
2.8
0.83
0.55
0.52
0.90
1.1
0.54
0.63
0.85
0.79
0.25
0.21
0.48
0.63
0.79
114 So.pl>.*!
Two SlJM Error Tern
PCI/1
I.I
0.081
0.074
0.067
0.085
0.092
0.0*7
0.067
0.081
0.078
0.042
0.042
0.063
0.069
1.2
-------
TABLi B-3,
AMBIENT OUTDOOR RADON-222 CONCENTRATIONS
LOCATION 1802-MILAN
TABLE B-4.
AMBIENT OUTDOOR RADON-222 CONCENTRATIONS
LOCATION 1803-BROADVIEU ACRES
Ttei
llrt/Jl
1«H
ii/tfH
OHO
n/lnm
ii/nm
14*3
ii/vj/n
tiltt
11115/7%
1 1/17/75
(Ml?
BUM
5835
11/W7S
8W5
tlrt5/ft
013J
nmtn
07H
11/J9/7S
CSS)
TZ/7/75
C9B
Surawrj
1W/J5
Off
8*t«
itn*
11B
11/wn
6740
ii/iom
n/iw/4
un
ll/Il/H
11/11/75
115J
I1/17/7S
I1/19/7S
8»J7
ll/JI/75
MM
11/21/75
Q8U
0750 '
12/1/75
12/3775
07*1
12/3/75
lta«ton*??i> THQ $i?B4 Error T»mt
ttCi/1 PCi/1
4.% 8.1»
?,4 0,14
?,1 0,11
o.n o.nf
1,4 0.11
1.5 O.U
3,» n.t?
i.i o.rnt
1.6 D. 1 1
4.3 0.18
1.1 0.087
— — .~_™_^ ,
0.52 0.0(5
O.t« 0.057
1.4 0.11
2.6 0.13
2.2 2.8
."SSJH>'«)
On
11/5/75
11/7/7S
07H
1I/B/7S
0745
11/10/71
0745
ll/IJ/75
11/14/71
074S
11/16/75
0730
11 mm
11/20/71
07S5
11/22/75
i 0810
11/24/75
0820
'< 080S
11/28/75
0750
11/30/75
0920
Surrary
11/5/75
Off
01 1*
Tlw
11/7/75
075S
11/8/7S
0735
11/10/75
0740
11/1Z/7S
07S3
11/14/75
0745
11/1C/75
0730
11/18/75
0823
11/20/75
0753
11/12/75
0810
11/24/75
0815
11/26/75
0803
11 mm
0745
11/30/75
091S
12/2/75
0850
12/2,75
Riaon-222
PCI/1
2.9
3.3
2.3
0.80
J.S,
2.7
3.4
l.S
1.6
2.6
1.Z
g-jj,
0.6S
3.6
2.1
(14 Samples)
THO Slgmj Error Tim
pC1/l
0.15
0.16
0.12
0.075
D.H
0.15
0.16
0.099
0.11
0.13
0.039
— wwt—
0.07J
0.16
2.2
-------
TABLE B-5.
AMBIENT OUTDOOR RADON-222 CONCENTRATIONS
LOCATION S804-AMBROSIA LAKE HIGHWAY JUNCTION
TABLE B-6.
AMBIENT OUTDOOR RADON-222 CONCENTRATIONS
LOCATION #805-SAN MATED
On
Date
Tine
11/5/75
1140
11/7/75
0825
11/10/75
0812
11/12/75
oaso
11/14/7S
OBOfl
11/16/75
07S6
11/19/75
0354
11/21/75
OS45
11/23/75
OSZ3
11/25/75
0850
11/Z7/75
0305
11/29/75
1015
12/1/75
0945
Sojjary
11/5/75
Off
Date
Time
11/7/7S
0820
11/9/75
0900
11/12/75
0825
11/14/7S
OB03
11/16/75
075S
11/19/75
085J
11/21/75
0845
11/23/75
OB20
11/25/75
oasti
11/27/75
oaoo
11/29, '5
1010
12/1/75
0940
1Z/3/75
0800
1Z/3/75
Ridon-ZZZ
PC1/1
3.4
1.2
0.63
2.1
3.4
1.2
2.4
3.2
1.3
0.48
0.21
1.9
2.R
1-9
Two Sigma Error Terra
pCi/1
0.15
0.099
0.074
0.12
0.16
0.090
0,14
0.15
0.10
0.064
0.04Z
0.12
0.14
z.z
On
Dtte
Time
11/6/75
1630
11/9/75
D935
11/10/75
1615
11/12/75
1536
11/13/75
1616
11/15/75
1430
11/17/75
0940
11/19/75
0958
"6K75
11/23/75
OB50
11/Z7/75
0955
11/29/75
1120
1110
Synary
11/6/75
Off
Date
Time
11 /a/75
0900
11/10/75
1614
11/12/75
1540
11/13/75
1615
11/15/75
142B
11/17/75
0338
11/19/75
0956
11/Z1/75
0955
'Ws
'W5
11/29/75
1115
12/1/75
1100
l?/2/75
1353
12/2/75
pCi/1
0.35
0.60
0.13
0.90
O.Z9
0.35
0.19
0.49
0.30
0.31
0.062
0.31
0.38
0.36
Two Sigraa Error Terra
Pd/1
0.05?
O.Obf
0.038
0.083
0.048
0.055
0.040
0.057
0.050
9,047
0.025
0.04C
0.05*
0.42
-------
TABLE B-7.
AMBIENT OUTDOOR RADON-222 CONCENTRATIONS
LOCATION 0806-AMBROSIA LAKE POST OFFICE
TABLE B-8.
AMBIENT OUTDOOR RADON-222 CONCENTRATIONS
LOCATION 1807-BLUEWATER
On
Date
tine
11/5/75
1525
11/7/7S
0835
11/9/75
0905
11/11/75
093?
11/13/75
OS20
11/15/75
0833
11/17/75
0850
11/19/75
0904
11/21/75
0905
11/23/75
0832
11/Z5/75
0915
11/27/75
0812
11/29/75
1040
1Z/1/75
1035
H/5/75
Off
Date
TiM
11/7/75
0530
11/9/75
0905
1V11/75
0931
11/13/75
08211
11/15/75
0833
11/17/75
0850
11/19/75
OOT3
11/21/75
0905
11/23/75
OB31
11/25/75
0903
11/27/75
0810
11/29/75
1035
12/1/75
1015
12/3/75
0845
12/3/75
Radan-222
pCi/l
4.2
3.9
1.0
1.8
3.1
3.9
2.8
2.5
5.4
4.1
2.0
1.1
3.2
3.9
<«JiU,
Two Sigma Error 7em
PCi/l
0.17
0.17
0.069
0.12
0.15
0.16
0.14
0.14
0.21
0.16
0.12
0,086
0.16
0.16
2.6
On
Date
Time
11/6/75
0930
11/8/75
093S
11/10/75
1710
11/12/75
1614
11/14/75
0942
11/16/75
0843
11/18/75
1105
iv?n/75
1030
11/22/75
1035
11/24/75
1035
0935
11/30/75
1535
Sjnary
11/6/75
Off
Dale
Time
11/8/75
09 3D
11/10/75
1700
11/12/75
1615
11/14/75
0942
11/16/75
0843
11/1B/75
1105
11/20/75
1029
11/22/75
1035
11/24/75
1035
11/26/75
1505
1530
12/2/75
1030
12/2/75
Sadorv-222
pCI/1
1.6
0.94
0.59
1.6
1.1
1.8
0.69
1.3
1.3
0.51
0.32
1.7
1.1
(12 Samples)
Two Sigma Error Term
PCI/1
0.11
0.085
0.068
0.11
0.087
0.12
0.074
0.0?3
0.099
0.061
O.OS2
0.11
1.0
-------
On
Date
Time
11/6/75
1040
11/8/75
0819
11/9/75
0915
11/11/75
0930
11/13/75
0811
11/15/75
0830
11/17/75
0845
11/18/75
0933
11/22/75
0945
11/24/75
0905
11/26/75
1325
11/29/75
1025
11/30/75
1015
Summary
11/6/75
TABLE B-9. AMBIENT OUTDOOR RADON-222 CONCE
LOCATION #808-AMBRQSIA LAKE TRAILER PA
Off
Date
Time
11/8/75
0818
11/9/75
0910
11/11/75
0925
11/13/75
0810
11/15/75
0829
11/17/75
0845
11/18/75
0700
11/20/75
0937
11/24/75
0900
11/26/75
1320
11/28/75
0816
11/30/75
1012
12/2/75
0953
12/2/75
Radon-ZZZ T
pC1/l
6.6
3.3
2.0
4.0
4.2
4.7
5.3
2.7
4.3
3.0
1.3
1,9
4.0
TRATIONS
k
D Sigma Error Term
pCi/1
0.22
0.16
0.12
0.18
0.17
0.18
0.19
0.13
0.17
0.16
0,099
0.12
0.17
3.6 3.0
Q3 Samples)
34
-------
APPENDIX C
METEOROLOGY
Meteorological data for this study were collected from
November 4-30, 1975 using a portable mechanical weather station1
at location »S02, east of the United Nuclear-Homestakp Partners
(UNHP) mill site. Wind speed and direction (3 meters above
ground surface) and ambient temperature were continuously
recorded at this station. In addition, the official daily high
and low temperatures and barometric pressures for thej Grants
Municipal Airport station were obtained from the U-S. National
Weather Service. Unfortunately, confirmation of inversion
conditions was not obtainable due to limitations of t|he mechani-
cal weather station.
Figure C-l shows the daily temperatures at loca
high of 73°F was recorded on November 5 and 17, and
minus 8°F on November 30, The average daily maximum
temperature was 54°F and 16°F, respectively, with a
(November, 1975) average daily temperature of 32"F,
diurnal variation (57°F) occurred on November 14, wi
65°F and a low of 8°F. Minimum diurnal variation (2
on November 28, with a high of S1°F and a low of 30
results can be compared to Figure C-2 which shows th
temperatures recorded at the Grants Municipal Airpor
C-3 shows the daily barometric pressure for the air
ion #802. A
low of
and minimum
onthly
Maximum
th a high of
F) occurred
These
daily
t. Figure
rt station.
Precipitation was not quantitatively measured alt field
location #802 but data were obtained for the Grants Municipal
Airport station. Total precipitation for November lp75 consisted
of 0.06 inches of rain on the 18th, and on November 29, four
inches of snow (0.38 inch rain equivalent) for a total monthly
precipitation of 0.44 inches. The official average monthly
precipitation for November at Grants is 0,60 inches (U.S. Navy,
1965). Measurements of the November 29 snowfall at(several air
sampling locations in the Ambrosia Lake area revealed snow depths
of seven to nine inches or about twice that measure^ in Grants.
Figure C-4 is the wind rose plot for field locjition 1802 Cor
November 1975. This plot represents the direction from which the
wind was blowing. Roughly one percent of the time the wind was
calm, i.e., less than one mile per hour (mph). Predominant winds
were from the north to northwest (about *3 percent of the time) ,
Meteorology Research, Inc., Model 1071-Mechanical Weather
Station.
35
-------
80
11/5
11/10
a-LOW
DATE
37
-------
80°-
65°.
? 50"-
c
a
D
| 35°-
0
20"
5°
0"
— 10"
v*-\ * A^-A1
w' > ' l
«* \ A1 *
\ ™ \
\ i \
\ / I
I / W *. A ^k A
i f ja er"" > /^*r
\ v' V ' S*
V ' \ ' \
"ifir " £& i
1
i
T\
^ K ;K
rf \ / t |
tr * * p-i *T n
\ ' ' rr rf" * ^ '
i ___,' * * * r
& \ v \ ! \
ta tf \i .ET v |
Q' M
i
k-HIGH
e-iow
' 1
H/5 11/10 11/15 11/20 11/25 11/30
DATE
FIGURE C-2. DAILY TEMPERATURES FOR NOVEMBER 1975 AT
THE GRANTS MUNICIPAL AIRPORT, MEW MEXICO
38
-------
30.70-
30.50-
30.30
29.90-
29.70.
29.50-*—r
/
V:
y \\
$
14
\k
HIGH
•Q LOW
11/5 11/10 11/15 11/20 11/28 11/30
DATE
FIGURE C-3. BAROMETRIC PRESSURE FOR NOVEMBER 1975 AT
THE GRANTS MUNICIPAL AIRPORT, NEW MEXICO
39
-------
w
8-12 .„)?•'•. 19
t$tti>w\
rVUIoi per Hour
FIGURE C-4. WIND ROSE FOR NOVEMBER 1975 AT FIELD
LOCATION #802, GRANTS, NEW MEXICO
40
-------
APPENDIX D
TABLE D-l, INDOOR RAOO,! PROGENY TADLE D-2. IUDOOR RADOfI
Location I800-H1lan City Hall Location 1801-Bluewater
On
Date
11/04/75
11/10/75
11/17/75
12/01/75
Summary
11/04/75
Off
Date
11/10/75
11/17/75
12/01/75
12/03/75
12/03/75
Total Working Level
Hours (WL)
148.7 .01292
164.7 .01420
319.8 .00832
54.1 .01615
687.3 0.0129
On
Date
11/04/75
11/08/75
11/10/75
11/16/75
11/20/75
11/21/75
11/24/75
11/26/75
11/27/75
11/28/75
11/30/75
Summary
11/04/75
Off
Date
11/08/75
11/10/75
11/16/75
11/20/75
11/21/75
11/24/75
11/26/75
11/27/75
11/28/75
11/30/75
12/02/75
12/02/75
Total
Hours
54.5
23.0
113.9
43.7
14.8
16.5
13.5
7.3
9.5
25.1
6.3
328.1
PROGENY
Village
Working Level
(WL)
.00670
.00213
.00074
.00871
.006~7
.00596
.00304
.00555
.00285
.00229
.00433
0.0045
-------
E 3-j. INDOOR RADON PROGENY
.Location 1802-Mllan
TftBLE D-4. IHDODR RADON PROGENY
Location I803-Broadv1ew Acres
On
Date
11/04/75
11/10/75
11/15/75
11/2Q/7S
SAgjify
11/04/75
Off
Date
11/10/75
11/15/75
11/20/75
12/03/75
12/03/75
Total
Hours
144.1
nz.8
120.0
320.1
697.0
Working Level
(WL)
.01885
.00997
.01300
.00919
0.0128
On
Date
11/05/75
11/10/75
11/15/75
11/20/75
Summary
11/05/75
Off
Date
11/10/75
11 /1 5/75
11/20/75
12/02/75
12/02/75
Total
Hours
125.4
112.8
12C.O
270.3
628.5
Working Level
fWLl
.03660
.02845
.02832
.01508
0.0271
-------
TABLE !)-5. INDOOR RADON PROGENY
location 1804-Ambrosia Lake Highway Junetion
TABLE n-5. INDOOR RADOH PROGENY
Location 1805-San Mateo
On
Date
11/05/75
11/07/75
11/11/75
11/16/75
11/17/75
11/20/75
11/21/75
11/24/75
11/25/75
11/26/75
11/28/75
11/30/75
Sunmary
11/05/75
Off
Date
11/07/75
11/11/75
11/16/75
11/17/75
11/20/75
11/21/75
11/24/75
11/25/75
11/26/75
11/28/75
11/30/75
12/02/75
12/02/75
Total
Hours
10.6
72.6
94.7
4.4
24.5
5.2
11.1
10.7
22.4
6.5
26.0
8.2
296.9
Working Level
(WL)
.01082
.00538
.01482
.00694
.01432
.02902
.00766
.00532
.00337
.00623
.00131
.01052
0.0096
On Off Total Working Level
Date Date Hours (WL)
11/05/75 11/10/75 122.6 .00305
11/10/75 11/15/75 112.7 .00247
11/15/75 12/01/75 385.2 .00170
Sunmary
11/05/75 12/01/75 620.5 0.0024
1
I
-------
TABLE IV7. INDOOR RADON PROGENY
Location |806-Ambros1a Lake Post Office
TABLE D-8. INDOOR RADON PROGENY
Location 1807-Bluewater
On
Date
11/05/75
11/10/75
11/13/75
11/17/75
11/20/75
11/22/75
12/01/75
Surma ry
11/05/75
Off
Date
11/10/75
11/13/75
11/17/75
11/20/75
11/22/75
12/01/75
12/03/75
12/03/75
Total
Hours
66.3
68.3
95.1
71.0
47.0
221.4
45.9
615.0
Working Level
(ML)
.03476
.01605
.02116
.02374
.02794
.01137
.04460
0.0257
On
Date
11/06/75
11/10/75
11/15/75
11/20/75
Summary
11/06/75
Off
Date
11/10/75
11/15/75
11/20/75
12/02/75
12/02/75
Total
Hours
100.6
112.6
120.8
252.1
586.1
Working Level
(WL)
.00787
.00692
.01068
.00524
0.0077
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TABLE (1-9. INDOOR RADON PROGEHY
Location jJIBOS-AmbrosIa Lake Trailer Park
On
Date
Off
Date
Total
Hours
Working Level
(WL)
11/09/75
11/11/75
11/14/75
11/19/75
11/22/75
11/24/75
11/26/75
12/01/75
12/03/75
12/03/75
56.9
43.1
28.6
101.8
47.0
35.6
50.7
97.6
25.2
486.5
.02131
.01450
.01794
.01534
.01071
.01584
.01340
.00485
.01927
0.0148
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