United States Office of EPA 520/1-87-014
Environmental Protection Radiation Programs Jury 1987
Agency Washington, D.C. 20460
Radiation
v>EPA Ground-Water Protection
Standards for Inactive
Uranium Tailings Sites
Background Information for
Proposed Rule
-------
EPA 520/1-87-014
July 1987
GROUND WATER PROTECTION STANDARDS
FOR INACTIVE URANIUM TAILINGS SITES
(40 CFR 192)
BACKGROUND INFORMATION
FOR
PROPOSED RULE
Office of Radiation Programs
Environmental Protection Agency
Washington, D.C. 20460
-------
Table of Contents
Chapter 1: Introduction 1-1
Chapter 2: Background 2-1
2.1 Legislative history 2-1
2.2 Rulemaking history 2-1
2.3 Legislation considered in developing the standards 2-2
Chapter 3: Site Description and Status 3-1
Chapter 4: Compilation and Analysis of Ground Water Data
for 12 Sites 4-1
4.1 Introduction 4-1
4.2 Ambrosia Lake, New Mexico—summary of water quality 4-3
4.3 Canonsburg, Pennsylvania—summary of water quality 4-18
4.4 Durango, Colorado—summary of water quality 4-26
4.5 Grand Junction, Colorado--summary of water quality 4-40
4.6 Gunnison, Colorado--summary of water quality .... 4-50
4.7 Lakeview, Oregon—summary of water quality 4-58
4.8 Mexican Hat, Utah—summary of water quality 4-72
4.9 Monument Valley, Arizona—summary of water quality 4-78
4.10 Riverton, Wyoming—summary of water quality 4-104
4.11 Salt Lake City, Utah—summary of water quality .. 4-118
4.12 Shiprock, New Mexico—summary of water quality .. 4-124
iii
-------
4.13 Tuba City, Arizona—summary of water quality ... 4-129
4.14 Current uses of contaminated ground water 4-137
4.14.1 Drinking water 4-137
4.15 Organic contaminants in ground water 4-154
4.16 Analysis of Ground Water Classification 4-167
4.16.1 EPA's ground water strategy 4-167
4.16.2 Ground water classification at
inactive mills 4-175
4.17 References 4-177
Chapter 5: Ground Water Restoration 5-1
5.1 Treatment technology 5-1
5.1.1 Introduction 5-1
5.1.2 Process and techniques 5-1
5.2 Treatment technologies and cost ranges
applied to 12 UMTRA project sites 5-12
5.2.1 Introduction 5-12
5.2.2 Site descriptions 5-13
5.2.3 Aquifer restoration cost ranges 5-17
5.3 References 5-20
Chapter 6: Costs of Ground Water Restoration 6-1
6.1 Amount of contaminated ground water 6-1
6.2 Amount of ground water to be removed 6-1
IV
-------
6.3 Treatment of contaminated ground water 6-3
6.4 Total estimated cost 6-3
6.5 References 6-5
Chapter 7: Other Considerations 7-1
7.1 Concentrations limits for molybdenum, uranium,
radium and nitrates 7-1
7.1.1 Molybdenum 7-1
7.1.2 Uranium 7-3
7.1.3 Radium 7-4
7.1.4 Nitrates 7-4
7.2 Institutional control 7-5
7.3 Ground water and precipitation effects 7-16
7.4 References 7-17
v
-------
Chapter 1
INTRODUCTION
In enacting the Uranium Mill Tailings Radiaton Control Act
of 1978 (Public Law 95-604, 42 USC 7901), the Congress found
that:
o "Uranium mill tailings located at active and inactive
mill operations may pose a potential and significant
radiation health hazard to the public, and that..."
o "Every reasonable effort should be made to provide for
the stabilization, disposal, and control in a safe and
environmentally sound manner of such tailings in order
to prevent or minimize radon diffusion into the
environment and to prevent or minimize other
environmental hazards..."
To these ends, the Act required the Environmental
Protection Agency (EPA) to set generally applicable standards to
protect the public against both radiological and nonradiological
hazards posed by residual radioactive materials at the 22
uranium mill tailings sites designated in the Act and at
additional sites where these materials are deposited that may be
designated by the Secretary of the Department of Energy (DOE).
Residual radioactive material means (1) tailings waste resulting
from the processing of ores for the extraction of uranium and
other valuable constituents, and (2) other wastes, including
unprocessed ores or low grade materials, as determined by the
Secretary of Energy, at sites related to uranium ore
processing. We will use the term tailings to refer to all of
these wastes.
Standards were promulgated on January 5, 1983, however,
they were challenged in the Tenth Circuit Court of Appeals by
several industrial and environmental groups (Case Nos. 83-1014,
83-1041, 83-1206, and 83-1300). On September 3, 1985, the court
dismissed all challenges except one: it set aside the
ground-water provisions of the regulations at 40 CFR
192.20(a)(2)-(3) and remanded them to EPA "...to treat these
toxic chemicals that pose a ground-water risk as it did in the
active mill site regulations."
In the active mill site regulations (40 CFR 192 Subparts D
and E), the EPA set general numerical standards to which the
owners/operators of the active sites had to conform to receive a
license from the Nuclear Regulatory Commission (NRC). For the
Title I sites, EPA set qualitative standards for ground water
1-1
-------
protection that allowed the DOE and NRC to determine what
actions were needed on a site-by-site basis. It was this
standard that was rejected by the courts and has resulted in the
rulemaking for which this is the Background Information Document
(BID).
The purpose of this draft BID is to summarize the
information and data considered by the Agency in developing the
proposed ground-water protection standards. Information in the
final environmental impact statements for previous rulemakings
for uranium mill tailings (EPA82, EPA83) was also considered in
this rulemaking. Further, the National Academy of Science
report, "Scientific Basis for Risk Assessment and Management of
Uranium Mill Tailings," (NAS86) was also considered by the
Agency.
Chapter 2 of the BID presents a brief description of the
Title II ground water standard and how it can be used to develop
the Title I rulemaking. A description of the 24 designated
uranium tailings sites and their current status in.the DOE
remedial action program is included in Chapter 3. Chapter 4
presents a detailed analysis of the available data on the ground
water in the vicinity of 12 of the 24 sites.
Chapter 5 describes different methods that can be used for
the restoration of ground water. DOE may use these methods or
may use others that they consider more appropriate. The costs
of using these restoration methods are discussed in Chapter 6.
Lastly, Chapter 7 contains other considerations pertinent to the
proposed standards.
References
EPA82 ENVIRONMENTAL PROTECTION AGENCY, Final Environmental
Impact Statement for Remedial Action Standards for
Inactive Uranium Processing Sites (40 CFR 192), EPA
520/4-82-013-1 and 2, U.S. Environmental Protection
Agency, 401 M St, SW, Washington, D.C. 20460 (October
1982)
EPA83 ENVIRONMENTAL PROTECTION AGENCY, Final Environmental
Impact Statement for Standards for the Control of
Byproduct Materials from Uranium Ore Processing (40 CFR
192), EPA 520/1-83-008-1 and 2, U.S. Environmental
Protection Agency, 401 M St, SW, Washington, D.C. 20460
(September 1983)
NAS86 NATIONAL ACADEMY OF SCIENCE, NATIONAL RESEARCH COUNCIL,
Scientific Basis for Risk Assessment and Management of
Uranium Mill Tailings, National Academy Press,
Washington, D.C. 20418 (1986)
1-2
-------
Chapter 2
BACKGROUND
2.1 Legislative history
The early history of uranium milling was discussed in
Chapter 2 of the Final Environmental Impact Statement for
Remedial Action Standards for Inactive Uranium Processing Sites
(40 CFR 192), EPA 520/4-82-013-1, October 1982. In 1978
Congress passed Public Law 95-604, the Uranium Mill Tailings
Radiation Control Act of 1978 (UMTRCA). UMTRCA was divided into
two parts; Title I covering 22 inactive and abandoned sites and
Title II covering those sites for which licenses had been issued
by the Nuclear Regulatory Commission or its predecessor or by an
Agreement State. Under this Act, the Environmental Protection
Agency was charged with developing standards of general
application to govern the remedial activities of the Secretary
of Energy or his designee under section 275a. of the Atomic
Energy Act of 1954 for those sites identified under Title I.
The Department of Energy identified two additional sites to be
included under the provisions of Title I, bringing the total
number of sites under Title I to 24. The standards to be
promulgated under Title I were required, to the maximum extent
practicable, to be consistent with the requirements of the Solid
Waste Disposal Act (SWDA) as amended. The SWDA includes the
provisions of the Resource Conservation and Recovery Act (RCRA).
2.2 Rulemaking history
On June 11, 1979, a Federal Register Notice requesting
information and data relevant to the development of the
standards and of a report to Congress on uranium mining wastes.
Because UMTRCA required EPA to promulgate standards before DOE
could begin cleanup of tailings and because some buildings had
been found to be contaminated with tailings resulting in
radiation levels which were highly dangerous to anyone exposed
to them for a long time, interim standards for cleanup of
residual radioactivity that had contaminated land and buildings
were published in the Federal Register on April 22, 1980. This
allowed DOE to proceed with the cleanup of offsite tailings
contamination without waiting for the formal promulgation of a
regulation through the EPA rulemaking process. At the same
time, proposed standards for the cleanup of the inactive mill
tailings were published for comment.
The proposed cleanup standards were followed by proposed
disposal standards that were published in the Federal Register
on January 9, 1981. The disposal standards applied to the
tailings at the 24 designated sites and were designed to place
2-1
-------
them in a condition which will be safe for a long time. Final
standards for the disposal and cleanup of inactive uranium mill
tailings were issued on January 5, 1983. The American Mining
Congress and others immediately petitioned the Tenth Circuit
Court of Appeals for a review of the standards.
On September 3, 1985, the Tenth Circuit Court of Appeals
upheld the inactive mill tailings standards except for the
ground-water protection portions located at 40 CFR 192.20(a)(2)
and (3) which were remanded to EPA for revision. EPA had
promulgated qualitative standards for ground water protection
and the Court found that quantitative standards similar to those
promulgated for the sites that were regulated under UMTRCA Title
II were necessary. The Court did not set a time limit on
establishing the new standards. On June 2, 1986, the U.S.
Supreme Court declined to review all appeals of decisions on
this case.
2.3 Legislation considered in developing the standards
In 1986, Congress passed the Superfund Amendments and
Reauthorization Act which amended the Comprehensive
Environmental Response, Compensation, and Liability Act of
1980. In the discussion of this bill, Congress established the
concept that the Administrator be allowed to use alternate
technologies where applicable standards set under other
environmental laws are based on specific technologies. The RCRA
amendments to SWDA provided only minimal direction from Congress
for the cleanup of old contamination that existed before RCRA
was promulgated. Therefore, EPA is considering using part of
the SARA philosophy in the the cleanup portions of the Title I
standards by incorporating some of the provisions from SARA into
the Title I ground-water standards. These provisions are an
exemption if it can be shown that the cleanup of contaminated
ground water is technically impracticable from an engineering
perspective and an exemption if it can be shown that cleanup of
the contaminated ground water would cause more environmental
harm than it would prevent if the water were not cleaned up.
The Office of Ground Water Protection in EPA has developed
draft guidelines for classifying ground water based on its use
or potential use as a source of drinking water. EPA proposes
allowing the use of alternate standards for Class III ground
water as defined by the ground water classification system
established in EPA's 1984 Ground Water Protection Strategy.
Procedures for classifying ground water are presented in
"Guidelines for Ground-Water Classification under the EPA
Ground-Water Protection Strategy" released in final draft in
December 1986 and due to be finalized during the summer of
1987. Under these draft guidelines, Class I ground waters would
encompass resources of particularly high value or that are
highly vulnerable; e.g. an irreplaceable source of drinking
2-2
-------
water or ecologically vital ground water. Class II ground
waters would include all non-Class I ground water that is
currently used or is potentially adequate for drinking water or
other beneficial use. Class III would encompass ground waters
that are not a current or potential source of drinking water due
to widespread, ambient contamination caused by natural or
human-induced conditions or inadequate capacity to provide
sufficient quantities of water to meet the needs of an average
household. Human-induced conditions would specifically exclude
the contribution from the uranium mill tailings being
regulated. At sites with Class III ground water, the proposed
supplemental standards would require only such management of
contamination due to tailings as would be required to prevent
any additional adverse impacts on human health and the
environment from that contamination. For example, if the
additional contamination from the tailings would cause an
adverse effect on a Class II aquifer that has a high to
intermediate degree of interconnection with the Class III
aquifer over which the tailings reside, then the additional
contamination from the tailings would have to be removed.
References
EPA79 ENVIRONMENTAL PROTECTION AGENCY, Development of Standards
for Uranium Mill Tailings and Report on Uranium Mining
Wastes; Call for Information and Data, U.S. Environmental
Protection Agency, Washington, D.C. 20460, Federal
Register, V. 44, No. 113, p. 33433 (June 11, 1979)
EPASOa ENVIRONMENTAL PROTECTION AGENCY, Interim Cleanup
Standards for Inactive Uranium Processing Sites, U.S.
Environmental Protection Agency, Washington, D.C. 20460,
Federal Register, V. 45, No. 79, pp. 27366-8 (April 22,
1980)
EPASOb ENVIRONMENTAL PROTECTION AGENCY, Proposed Cleanup
Standards for Inactive Uranium Processing Sites;
Invitation for Comment, U.S. Environmental Protection
Agency, Washington, D.C. 20460, Federal Register, V. 45,
No. 79, pp. 27370-5 (April 22, 1980)
EPA81 ENVIRONMENTAL PROTECTION AGENCY, Proposed Disposal
Standards for Inactive Uranium Processing Sites;
Invitation for Comment, U.S. Environmental Protection
Agency, Washington, D.C. 20460, Federal Register, V. 46,
No. 6, pp. 2556-63 (January 9, 1981)
EPA82 ENVIRONMENTAL PROTECTION AGENCY, Final Environmental
Impact Statement for Remedial Action Standards for
Inactive Uranium Processing Sites (40 CFR 192), EPA
520/4-82-013-1, U.S. Environmental Protection Agency, 401
M St, SW, Washington, D.C. 20460 (October 1982)
2-3
-------
EPA83 ENVIRONMENTAL PROTECTION AGENCY, Standards for Remedial
Actions at Inactive Uranium Processing Sites, U.S.
Environmental Protection Agency, Washington, D.C. 20460,
Federal Register, V. 48, No. 3, pp. 590-606 (January 5,
1983)
2-4
-------
CHAPTER 3
SITE DESCRIPTIONS AND STATUS
There are 24 processing sites (Fig. 3-1) designated under
Title I of the Uranium Mill Tailings Radiation Control Act
(UMTRCA). All but one of these sites are located in the
generally semi-arid to arid western United States. Detailed
site descriptions have been presented in Engineering Assess-
ment Reports prepared on each site for the Department of
Energy by Ford, Bacon & Davis Utah Inc. These have been
supplemented by more specific site investigations, remedial
action plans, environmental analyses and detailed ground
water quality investigations as necessary.
The sites vary in location from isolated sparsely-populated
rural settings to populated urban communities. Demographic
information for each site is presented in Table 3-1.
The sites typically are in areas of alluvium underlain by
poorly to moderately consolidated sedimentary formations.
Ground water tends to be scarce and of poor quality.
Pertinent summary information regarding the topography,
geology, hydrology, and soil characteristics of each site is
presented in Table 3-2.
The majority of the sites occur in the semi-arid to arid
western United States, in areas characterized by infrequent
but often very intense rainstorms. In the northern areas,
much of the annual precipitation may occur in the winter
months as snowfall. Site-specific precipitation and wind
records for many of the sites are lacking because of the
remote locations. Meteorological information from the
nearest comparable localities are summarized for each site
in Table 3-3.
The tailings contain residual radioactive materials, in-
cluding traces of unrecovered uranium and most of the
daughter products, as well as various heavy metals and other
elements often at levels exceeding established standards.
The quantity of tailings, contained radioactivity, and
proposed remedial action are summarized for each site in
Table 3-4. The concentrations of specific elements which
could present public health risks through ground water con-
tamination are given in Table 3-5.
All of the sites investigated show at least local contam-
ination of groundwater by surface waters and precipitation
leaching through the tailings materials. Areal extent of
contamination ranges from the immediate vicinity of the site
to as far as 1/2 mi down-gradient. Available groundwater
contamination data are summarized in Table 3-6.
3-1
-------
United States Department of Energy
Uranium Mill Tailings
Remedial Action Program
UMTRA SITE LOCATIONS
co
ro
O BGLFELO
BOWMAN
CANONSBURQ
A RIFLE (2 I
A GRAND JCT.
NATURITAIQ £ QUNMSON
SUCKROCK (21
MEXICAN HAT
MONUMENT O
DURANQO
SHIPROCK
D
AMBROSIA
LAKE
PRIORITIES
FALLS CITY
D
MQH HEALTH HAZARD
O MEDIUM HEALTH HAZARD
O LOW HEALTH HAZARD
NOTE: EDQEMONT SOUTH DAKOTA VICINITY
PROPERTIES ONLY
Figure 3-1. LOCATION - UMTRA PROJECT SITES
-------
Table 3-1. DEMOGRAPHICS OF INACTIVE UKANIUH MILL TAILINGS SITES
SITE NAME
Honument Valley, AZ
Tuba City, A2
Durango, CO
Grand Junction, CO
Gunnison, CO
Haybell, CO
Naturita (BE), CO
Ney Rifle, CO
CO
I Old Bifle, CO
Lo
Slick Sock (NO, CO
Slick Rock (UC), CO
Louaan, ID
Ambrosia Lake, NM
Shiprock, NM
Bel fie Id, ND
Bowman , ND
Lakeviey, OB
Canonsburg, PA
Falls City, TX
Green River, UT
Mexican Hat, UT
Salt Lake City, UT
Converse Co. , HY
Rlverton, HY
COUNTY
NAME
Navajo
Cocon ino
La Plata
Mesa
Gunn ison
Moffat
Hontrose
Carf ield
Garf ield
San Miguel
San Miguel
Boise
HcKlnley
San Juan
Stark
Bouman
Lake
Washington
Ka-rnes
Grand
San Juan
Salt Lake
Converse
Fremont
POPULATION
0-lkn 0-3k» O-5km
2O 44 6O
18 45 64
1221 726O 12O58
843 16634 38011
396 6523 7315
000
333
96 693 723
1471 5251 5659
5 1O 1O
39 39 39
85 172 218
022
155 3O93 4948
65 1428 1584
3 15 33
16 2263 4184
3910 17O24 22135
3 21 45
14 1081 1498
4 384 384
203 18468 91498
O 9 18
83 1OB9 11738
NEABEST COMMUNITY
NAME DISTANCE
Monument
Valley
Tuba City 5.5mi
Durango
Grand
Junction
Gunnison
Craig 25mi
Naturita 2«i
Eifle
Eifle
Slick Bock 3mi
Slick Rock 3mi
Lowman
Grants 25mi
Shiprock
Belfield O.Smi
Bowman 7mi
Lakeview
Canonaburg
Falls City lOmi
Green River 1ml
Mexican Hat 1.5mi
Salt Lake
City
Glenrock 32ml
Rlverton 3mi
LOCAL LAND USE
rural grazing, IK*
rural grazing, IK*
urban, industrial
urban, industrial
urban
rural grazing
rural grazing
urban, agri-
cultural
urban, agri-
cultural
rural, grazing
rural, grazing
rural, grazing
rural, grazing
urban, mixed, IK*
urban, industrial
rura 1, agri-
cultural
urban, industrial
urban, industrial
rural, graz ing
urban, mixed
rural, grazing, IK*
urban, industrial
rural, grazing
urban, mixed, IK*
WATER USES IN AREA
2 alluvial well and seeps, domestic Be livestock
2 sources ulthin 2 ml
none within 2 mi
local sources from deeper aquifers
numerous shallow domestic wells within 1 mi of site
domestic water wells 4-6 ml from site
3 alluvial wells upgradient, river water downstream
used for irrigation, 1 deep well within 2 ml
47 gells within 2 mi, 1 used by South Rifle for domestic
water, Colorado River major source of domestic water
local needs supplied by deep bedrock aquifers
shallow wells and surface water usage
none known
local use of groundwater from floodplaln
scattered domestic and stock use
domestic and stock use
domestic, irrigation and municipal uells 1OO' or more
none known
4 livestock wells within 2 ml
no groundwater usage near site; Green Elver fa tapped
none known
shallow water not used, numerous domestic wells
few local wells, domestic and stock watering
local wells below 100 ft; limited use of shallower
water
* Indian Reservation
-------
Table 3-2. SUHHASY DESCRIPTIONS OF INACTIVE URANIUM HILL TAILINGS SITES
Monument Valley, AZ
Tuba City, AZ
Location, The site is on the Navajo Indian Reservation in Cane Valley,
Topography east of Monument Valley, AZ. The area is arid desert uith hills,
steep ridges, and mesas. Red sandstone cliffs are prominent on
the west edge of Cane Valley.
The site is on the Navajo Indian Reservation, 5.5 ml east of Tuba
City in Coconino County, AZ, and 85 mi north of Flagstaff. The
area includes occasional dry washes, mesas, and rolling hills.
Geology
U>
I
.c-
The site is located in a strike-valley developed on shale members
of the Chinle Formation. The site is bordered on the west by an
outcropping of the Shlnarump Member of the Chinle Formation and
on the east by Comb Ridge, a hogback of resistant sandstones of
Triassic and Jurassic age.
The tailings rest on a sand layer from less than 1 ft to 20 ft
thick derived from the underlying Navajo Sandstone, a weakly
cemented, medium-grained, crossbedded sandstone. The Navajo
Sandstone dips at a low angle (2 deg) away from the town of Tuba
City towards the axis of the Tuba City syncline. This axis runs
in a northwest-southeast direction about 1 ml east of the tall-
ings site. The Navajo Sandstone is exposed south of the mill-
site along Moenkopi Hash.
Surface Water There are no continually active streams in the area. The site
Hydrology drains naturally into Cane Valley Hash. Approximately 1,000
acres of land are in the drainage basin that passes through the
tailings area to the wash.
There are no surface waters of consequence near the Tuba City
tailings site. Surface drainage runs to the Moenkopi Hash about
1.5 mi south of the tailings. There is evidence of minor sheet
erosion in the area. To the north of the highway, a large de-
pression known as Greaseuood Lake depression drains to the west-
southwest.
Ground Hater Unconflned ground water is very near the surface along the main
Hydrology axis of Cane Valley Hash because the area is underlain by imper-
meable beds of Monitor Butte and Petrified Forest members of the
Chinle formation. These members consist of slltstones and clay-
stones and are about 700 ft. thick in the millsite area. The un-
confined water moves through the alluvium of Cane Valley Hash and
is recovered near the site from shallow wells. These shallow
wells and springs are water table sources and their recharge is
from local runoff.
The principal aquifer in the Tuba City-Moenkopi area is a mul-
tiple aquifer system consisting of the Navajo Sandstone and some
sandstone .beds in the underlying Kayenta Formation. This aqulfor
is recharged by winter and spring precipitation In the Kalblto
Plateau highlands some distance north of Tuba City. Hater in the
multiple aquifer system moves southward from the highlands; its
principal discharge area Is along Moenkopi Wash. Thus, the tail-
ings are situated in the discharge rather than the recharge area
of the aquifer system. Water in this multiple aquifer system is
uncon f ined.
Haste and Soil
Character 1st ics
The new tailings pile (85X) is coarse-grained sand and small
pebbles containing less than 2X minus 200-mesh material. The old
tailings pile (15X) is slightly finer. Bulk densities run be-
tween 97 and 1O3 Ib/cu ft. Soil beneath both piles is mainly
fine-textured sand containing little moisture. The Chinle Forma-
tion underlies this alluvium.
The tailings are finely ground particles, a high-clay content,
relatively impermeable, and can hold water. The subsoil consists
mainly of sand and small aggregate eroded from the underlying
Navajo Sandstone.
-------
Table 3-2. SUMMARY DESCRIPTIONS OF INACTIVE URANIUM MILL TAILINGS SITES (confd)
Durango, CO
Grand Junction, CO
Location, The site is located on the southwest side of the city of Durango,
Topography in the valley of the Animas River. The area is surrounded by
mesas and mountains typical of the western slopes of the Rocky
Mountain Range.
The site is located on the south side of the city of Grand
Junction, CO, on the north bank of the Colorado River and adja-
cent to the industrial center of the city. The site is located
in the valley of the Colorado River, surrounded by generally arid
mesas and mountains.
Geology
u-
I
Ln
The site is on a shelf between the Animas River on the northeast
and the sharply rising Snelter Mountain on the southuest. The
tailings generally lie directly on Mancos Shale bedrock, but some
of the piles are on alluvium and on slag from the old lead smel-
ter. The bedrock strata dips 5 to 10 deg southeastward. The
Mancos Shale is hundreds of feet thick beneath the tailings and
acts as a barrier to the downward and upward migration of ground
waters.
The site is located on the modern flood plain of the Colorado
River. A relatively thin (2OO-ft) section of remaining Mancos
Shale underlies the unconso1idated riverbed deposits and acts as
a barrier to the downward and upward migration of ground water.
The bedrock strata dip 5 to 10 deg toward the southwest.
Surface Hater Flowing surface waters near the site consist of Lightner Creek
Hydrology and the Animas River. Neither an intermediate regional flood
(100-yr flood) nor a more severe standard project flood would
reach the tailings nor would such floods erode the slag bank
material which provides excellent protection for the toe of the
large pile. Even so, the potential for flooding at the present
location is significant because of the nearness of the site to
the Aninas River.
Flowing surface waters near the site consist of the Colorado
River, a drainage ditch, and several man-made facilities associ-
ated with earlier operations at the site. The Colorado River at
Grand Junction has a long history of flooding. During an inter-
mediate regional flood (lOO-yr flood) or a more severe standard
project flood, the tailings pile would be an Island surrounded by
flood waters with unconfined ground water rising as much as 1O ft
into the pile.
Ground Hater The unconfined aquifers in the Durango area consist of waters
Hydrology within the recent valley alluvium and glacial deposits. However,
it is possible that ground waters flowing through the unconsoli-
dated material could be contaminated by any such seepage. The
Hancos Shale acts as a virtually impermeable layer confining the
waters of the Dakota Sandstone. There is no possibility for con-
tamination of this potential aquifer.
The unconfined aquifers in the Grand Junction area consist of
waters within alluvial deposits, terrace deposits, weathered
rocks and soils, and in the Nancos Shale. The water table asso-
ciated with the Colorado River fluctuates several feet during the
year and nay saturate some of the loweroost tailings. Any conta-
mination due to water table fluctuations would be carried by un-
confined ground waters Into the Colorado River. The Mancos Shale
acts as a virtually impermeable layer that confines the waters of
the Dakota Sandstone and other stratigraphically lower aquifers.
Haste and Sol 1
Character!sties
Materials consist of uranium and vanadium tailings, lead smelter
slag, rubble, and contaminated earth. The tailings consist of
grey, finely ground sands with a low clay content, and bulk den-
sities of the material range between 95 and 102 Ib/cu ft.
Materials include uranium and vanadium tailings, rubble, and con-
taminated earth. The tailings consist of gray, finely-ground
sands and purple alines. Bulk densities of the materials range
between 70.1 and 109.9 Ib/cu ft.
-------
Table 3-2. DESCRIPTIONS OF INACTIVE URANIUM HILL TAILINGS SITES (cont'd)
Cunnison, CO
Maybell, CO
Location,
Topography
The site is located on the southwest side of Gunnison, in the
valley of Gunnison River and Tomichi Creek. The area is sur-
rounded by mountains which rise to 12,000 ft above sea level.
The site is located approximately 25 mi west of the town of
Craig, 5 mi north of the Yampa River in a rolling, sagebrush-
covered area.
Geology
The site is located on flood plain gravels of the Gunnison River
and Tomlchi Creek. The unconsolidated river-run material under-
lying the site is at least 100 ft thick and probably 200 ft
thick. Bedrock geology consists of Mesozoic sedimentary rocks
that overlie Frecambrian igneous and metamorphic basement.
The site is located on a gentle southwestern, slope near the head
of a small drainage system. The Browns Park Formation underlies
the site and in turn is underlain by the Hancos Shale Formation.
The Browns Park Formation primarily is composed of sandstone
units, and some shale layers within the formation act as barriers
to the downward and upward migration of ground waters.
Surface Water
Hydrology
The tailings pile is located 1.5 mi from the confluence of the
Gunnison River and Tomichi Creek. Flooding of the tailings as a
result of peak discharges of these rivers is unlikely because the
land surface at the tailings is 10 ft above the stream beds and
the flood plains are extensive. Under unusual conditions, such
as ice jams in the Gunnison Siver at the bridge of U.S. Highway
50, some of the tailings could become saturated by flood waters.
The natural surface drainage from the site is to the southwest to
the Gunnison River or to Tomichi Creek.
The Yampa River, 5 mi south, is the closest perennial stream
flowing through the area downdrainage from the site. Drainage at
the site includes diversion ditches around the pile and drainage
channels into Johnson Hash, a dry tributary of Lay Creek. Lay
Creek enters the Yampa River approximately 2.5 mi downstream of
Johnson Wash. Other surface water near the site consists of
standing water in the inactive Rob Pit.
Ground Hater
Hydrology
The unconfined ground water in the unconso1idated riverbed Bate—
rial of the valley floor is the major aquifer for city and pri-
vate water supplies. The general direction of ground water flow
parallels surface water flow to the southwest. The city's water
supplies are upgradient from the pile. There are water wells
southwest of the pile and a potential for additional ground water
development. There has been no evidence of contamination of
ground or surface waters, but there is a potential for such con-
tamination.
The unconfined ground waters of the area are within the Brouns
Park Formation and in unconsolidated valley deposits. The water
table at the site is 150 ft below the tailings-soil interface,
and the flow gradient is to the west—southwest. The confined
ground waters are either contained in the lower sections of the
Browns Park Formation by shale layers, or are very deep aquifers
confined by the thick sequence of Hancos Shale.
Haste and Sol 1
Character 1stics
The material consists of uranium tailings, dike material, and
stabilization cover. The tailings are gray-to-white finely
ground sands with a medium clay content; bulk densities of the
material range between 114.6 and 127.5 Ib/cu ft.
Finely-ground sands with some slime and slight clay contents.
Bulk densities run between 84 and 97 Ib/cu ft. The soil beneath
the tailings consists of clayey and silty fine sands, of mediUD
density.
-------
Table 3-2. SUMMARY DESCRIPTIONS OF INACTIVE URANIUM MILL TAILINGS SITES (cont'd)
Naturita, CO
Rifle, CO (Old Rifle, New Rifle)
Location,
Topography
The site is located 2 mi northwest of the town of Naturita, in
the San Miguel River Valley. The locale is arid with canyons,
mesas, steep cliffs, and valleys.
The original tailings site was Just east of Rifle; later dis-
posal was on land about 2 mi west of Rifle. Both sites are on
the north bank of the Colorado River.
Geology
CO
I
The site is located on the uest bank of the modern flood plain of
the San Miguel River, which flows northwestward through the nar-
row San Miguel River Valley. Approximately 50 ft of alluvium
overlie the shales, sandstones, and conglomerates of the Brushy
Basin Member of the Morrison Formation. Bedrock strata dip 2 to
4 deg northeastward. The Brushy Basin Member is 100 to 20O ft
thick and is underlain by the sandstones and shales of the Salt
Hash Summerville Formation.
The sites are on unconsolidated Colorado River alluvium, under-
lain by the Shire Member of the Uasatch Formation. In this area
the member is characterized by up to 1600 ft of thick impermeable
claystone and siltstone beds. Geologic structure includes the
Piceance Basin north and west of Rifle and the White River uplift
northeast. The Uasatch Formation dips 3 deg or less to west or
northwest at the site.
Surface Water Flowing surface waters adjacent to or near the site consist of
Hydrology the San Miguel River and intermittent streams that drain the
neighboring canyons. Waters have flowed onto the former pile
area fro« the diversion ditch along the southwestern border of
the site and from drainage at the northwest of the site. The
area has been inundated by flood waters since the tailings were
removed.
Surface water at the sites Include drainage ditches, water-
accumulation ponds, and some marsh areas. Both sites are in the
floodplain of the Colorado River. The main channel has undergone
six major redirections in the past 100 years because of major
floods. Computed flows are 45.OOO cfs for 100-year flood and
65,000 cfs for 500-year flood but, because of the wide floodplain
in this area, flood velocities would be on the order of 3 feet
per second.
Ground Hater
Hydrology
The unconfined aquifers in the San Miguel River Valley consist of
waters within the recent valley alluvium. Except during flooding
season, the water table lies 3 to 1O ft below the former tail-
ings-subsoil interface. During an intermediate regional flood or
•ore severe floods, the water table would rise within the allu-
vium. Potential confined ground water aquifers consist of sand-
stone strata within the Morrison Formation and the sandstone
units within the Entrada Formation. The Summerville Formation
separates the Morrison Formation from the Entrada Formation and
prevents downward migration of water.
Both bedrock and alluvial groundwater subsystems are present.
The bedrock system, the Molina Member of the Uasatch is under
artesian pressure and probably provides a small recharge to the
alluvial system. At the old site alluvial ground water repre-
sents a small, nearly isolated system recharged by flow from the
river, precipitation, and return irrigation flows. A ground
water mound beneath the pile keeps the tailings saturated even
during periods of low water. At the new site the alluvial aqui-
fer is recharged by infiltration from the Colorado River, preci-
pitation, side-channel flow, and seepage from Rifle sewage faci-
1ities.
Uaste and Soil
Characteristics
The tailings were removed from the site and reprocessed. The
soil beneath the former tailings pile area is composed of allu-
vial deposits of the San Miguel River.
Materials include uranium and vanadium tailings, rubble, conta-
minated earth and stabilization cover. The tailings are on un-
consol idated Colorado River alluvium 16 to 21 ft thick at the old
site and 20 to 25 ft thick at the new site.
-------
Table 3-2. SUMMARY DESCRIPTIONS OF INACTIVE URANIUM MILL TAILINGS SITES (cont'd)
Slick Sock, CO (Union Carbide, North Continent)
Louman, ID
Location,
Topography
Two sites, the Union Carbide Corporation (UC) site and the North
Continent (NO site, about 0.9 mi apart. The sites are located
approximately 25 ni north of Dove Creek, CO, and 3 mi northwest
of Slick Rock, CO, in the Dolores River Valley.
The site is located approximately 75 ml northeast of Boise, ID,
in a pine-covered mountain valley in the Boise National Forest,
on a west-facing terrace of the Sawtooth Mountain Range. Drain-
age from the site is into Clear Creek .
Geology
CO
The sites are located on the flood plain of the Dolores River.
Bedrock consists of sedimentary strata: Navajo Sandstone at the
UC site and the Salt Wash Member of the Morrison Formation at the
NC site. The bedrock strata dip gently to the northeast.
The site is located on a glacial terrace, incised by Clear Crook.
A lower river-laid terrace, on which a settling pond area was
constructed, is adjacent to the higher nillsite terrace. The
glacial terrace material is composed of deep sandy and loamy
soils, gravels, sands, boulders, and cobbles. The lower alluvial
terrace is river-run material. Igneous granite bedrock
(granodiorite), underlies the site.
Surface Hater
Hydrology
Ground Hater
Hydrology
The flowing surface waters near the sites consist of the Dolores
Siver and three of its tributaries. An intermediate regional
flood (100-yr flood) or larger flood would inundate the base of
the piles and could erode part of the UC dike earth cover and
possibly the tailings themselves. The flow of flood waters
across the base of the NC site would not be as swift. Overland
flow across the piles is limited almost entirely to the precipi-
tation that falls on the piles.
Contamination of confined water systems theoretically is possible
because the bedrock strata are permeable and waters of the
Dolores River recharge the aquifers. The quantity of recharge
fro* the Dolores River would dilute any leaching from the tail-
ings piles.
Flowing surface waters near the site include Clear Creek, the
South Fork Payette River, and intermittent flow In ditches on the
site. Clear Creek, a swiftly flowing stream, intersects the
South Fork Payette River approximately O.5 mi south of the site.
The lower terrace which borders the creek could be eroded by
flood waters of Clear Creek, with resulting undercutting and ero-
sion of the piles. Erosion at the site, aggravated by the steep
banks of'the piles, has resulted in gullies up to 10 ft deep.
Local aquifers are shallow and unconflned. Clear Creek and the
South Fork Payette River are gaining streans fed by flows from
unconfined ground waters. The terrace materials tend to filter
sediments from the waters and act as buffers to regulate overland
and subsurface flow. The interface between the unconsolidated
surficial materials and bedrock acts as the surface for lateral
ground water flow. Seeps and springs are common in the area,
particularly at the exposure of this Interface.
Haste and Soil
Characteristics
The UC tailings are coarse-grained sand, while the NC tailings
are finer-grained with a clay content. Bulk densities run be-
tween 88 and 97 Ib/cu ft.
The materials are angular, dense, coarse-grained sands; some
gray and white, black (magnetite) and red (garnet). The under-
lying soil is mountain loam, nearly black in color, with gravelly
aggregates resulting from glacial deposits in some locations.
-------
Table 3-2. SUMMARY DESCRIPTIONS OF INACTIVE URANIUM MILL TAILINGS SITES (confd)
Ambrosia Lake, NM
Shiprock, NM
Location,
Topography
The site is located in a valley 25 mi north of Grants and 85 mi
northuest of Albuquerque, NM. Mesas and steep cliffs surround
the valley and reach elevations about ZOO ft above the site.
The site is located on the Navajo Indian Reservation, on the
south side of the San Juan River at the town of Shiprock, NH.
The area is arid and desert-like, with low rolling hills and oc-
casional steep ridges and mesas.
Geology
The site is on a pediment sloping southuestuard from the base of
San Mateo Mesa. The underlying Mancos Shale bedrock dips gently
toward the northeast, opposite the direction of surface drainage,
and acts as a barrier to the downward and upward migration of
ground water in bedrock. Unconsolidated materials separating the
tailings pile from bedrock are composed of clays and silts, .con-
tain some water, and do not exceed 15 ft in thickness.
The site is situated on an ancient river terrace adjacent to the
southwest bank of the San Juan Kiver. Up to 10 ft of terrace de-
posits form a layer between the Mancos Shale and the tailings.
The materials are poorly sorted and range in size fron 12-in
boulders to sand- and silt-sized particles that are cemented to-
gether in places. The Hancos Shale directly below this alluvium
is at least several hundred feet thick.
Surface Water There are no perennial surface streams near the site. Dry washes
Hydrology drain near the site and some runoff can flow toward the site.
Surface waters near the site include ponded waters on the tail-
ings pile itself and near the mill. Tailings have been eroded
from the pile by storm runoff.
The elevated topography at the millsite eliminates the possibi-
lity of flooding or erosion of the tailings by the waters of the'
San Juan River. South and west of the tailings, the terrain is
relatively flat near the site. Drainage from the higher ground
farther to the south is carried to Dead Mans Wash, which empties
into the San Juan Slver about 0.5 ml southeast of the site.
Ground Mater The tailings lie on unconsolidated materials which contain some
Hydrology unconfined ground waters. Seepage through the pile is possible.
The confined ground waters of the area are protected by Hancos
Shale from the downward flow of contaminants from the tailings
pile. The Dakota Sandstone underlies the Mancos Shale and la a
potential aquifer. The Hestwater Canyon Sandstone Member of the
Morrison Formation is tapped as the major aquifer in the area,
which is unusual since it serves as the chief uranium-bearing
horizon of the vicinity.
The confined ground water aquifers underlying the site are pro-
tected against contamination by both an upward pressure gradient
and thick impermeable strata. There is a potential for further
contamination of the terrace gravel immediately underlying the
tailings piles if sufficient water la allowed to collect and
percolate through the piles.
Waste and Soil
Characteristics
The tailings are white to pink finely-ground sand with some clayi
bulk densities range from 100 to 108 Ib/cu ft. Material beneath
the aite ia a thin alluvial layer of clay and silt derived from
the surrounding highlands.
Materials include a combination of uranium and vanadium tailings,
dike material, rubble, and stabilization cover of pit-run gravel.
Bulk densities range between 82 and 107 Ib/cu ft. The aoll on
the site is a combination of decomposed shale and a conglomerate
of river-deposited sand and cobbles.
-------
Table 3-2. SUMMARY DESCRIPTIONS OF INACTIVE URANIUM MILL TAILINGS SITES (confd)
Lakeview, OR
Canonsburg, PA
Location,
Topography
The site la located in Goose Lake Valley 96 mi east of Klanath
Falls. OR. Mountains surrounding the site on the east and west
reach elevations of 8,000 ft.
The site is located within the corporate Units of the borough of
Canonsburg, PA. The site slopes to the east toward Chartiers
Creek.
U)
I
Geology
The Lakevieu site Is located in an unconsolidated valley fill
consisting of clays, sands and gravels that overlie sedinentary
rocks of lacustrine and fluvial origin. The site is at the
eastern boundary of the Goose Lake Graben, which is block-faulted
by northerly and northeasterly normal faults.
The unconsolidated materials at the site are of fluvial origin.
Underlying these deposits are sedimentary strata of the Penn-
sylvanian Systen, consisting of sandstone with a little conglo-
merate, shale, limestone, clay, and numerous beds of coal. The
site lies on top of the Coneaaugh Formation, which is predomi-
nantly shale with abundant sandstone beds and some limestone,
clay, and coal.
Surface Water
Hydrology
The surface waters near the site consist of drainage ditches,
ponded water after rains, and an unnamed stream from Hammers ley
Canyon that is routed between the tailings pile and the adjacent
evaporation ponds. There is no evidence that the stream flow has
eroded the tailings pile or the embankments surrounding the eva-
poration ponds.
Abundant surface waters in the area include several streams, nu-
merous intermittent drainages, and several reservoirs and ponds.
Surface waters in the vicinity of the site include Chartiers
Creek and several ditches which carry runoff. At a gauging sta-
tion in Carnegie, about 12 mi northeast of Canonsburg, the annual
average flow of Chartiers Creek was recorded at 287 cfs. The
estimated annual average flow of Chartiers Creek in Canonsburg is
between 90 and 130 cfs.
Ground Water
Hydrology
Ground water occurs under confined and unconfined conditions.
There is a strong upward flow gradient from leaky artesian aqui-
fers in the thin, unconsolidated lacustrine sediments. Conta-
mination of the ground water is unlikely. A known geothermal
area is located adjacent to Warner Mountain, and the surface
water temperature at Hunters Hot Springs, 1 ml northwest of the
site, is 212 F.
Confined ground-water systems in the Conemaugh Formation under
the site occur largely in the sandstone beds with limited quanti-
ties in the bedding-plane passages and in joint planes of the
shales and limestones. Yields are variable and unpredictable but
generally range from small to moderate. A median yield for wells
in this aquifer is 5 gal/nin. Yields large enough for Industrial
or municipal purposes are difficult to obtain. Unconfined ground
water at the site is found in fill materials and in alluvial
deposits.
Waste and Soil
Characteristics
The uranium tailings are of a fine brown sand. The natural soil
on which the tailings rest is a rich dark brown-to-black loam.
Tailings have been stabilized in place.
-------
Table 3-2. SUMMARY DESCRIPTIONS OF INACTIVE URANIUM MILL TAILINGS SITES (confd)
Bel fie Id, ND
Bowman, ND
Locat ion,
Topography
The site is located about 19 mi west of Dickinson, ND, on nearly
level land immediately south of the North Branch of the Heart
River. The Heart River, an intermittent stream, flows generally
west to east in a channel 1O to 15 ft below the general elevation
of the site.
The site is at the Griffin siding about 7 mi west of Bowman. It
is on nearly level land near the head of Spring Creek, a part of
the Grand River drainage basin. An intermittent drainage to the
west joins Spring Creek less than 0.5 mi southwest of the site.
Geology
The site is located on alluvial deposits of the Heart River which
are largely silt and clay with a few beds of sand and gravel.
Underlying bedrock is poorly consolidated. A lignite bed occurs
at 50 ft depth. In many localities scoria beds are present, from
burned lignite beds.
The site is underlain by the Bullion Creek Formation, sometimes
called the Tongue River in this area. The formation consists of
light layers of silt, clay, and sand with interbedded sandstone,
lignite, baked clay, and limestone.
Surface Water
Hydrology
The site is located on the south side of the north branch of the
Heart River. In the vicinity of the site, the river is an inter-
mittent stream draining only a small area. During summer months
there may be areas of stagnant water in the streambed. Surface
flows arise only from rainfall directly on the site. Precipita-
tion on the site drains either to the Heart River or to ponds on
the site.
The site is located 1 mi north of Spring Creek in the headwaters
of the North Fork of the Grand River, a tributary of the Missouri
River. A small intermittent drainage runs along the west side ol
the site and joins Spring Creek 0.5 mi southwest of the site.
Precipitation tends to pond in local low spots and generally eva-
porates with some infiltration into the clayey-silty soils on the
site. Numerous small reservoirs in the vicinity of the site are
generally used for stockwater, irrigation, and recreation.
Ground Hater There are four major usable aquifer systems underlying the site.
Hydrology The uppermost, the Sentinal Butte Formation, outcrops much of the
area and supplies rural livestock and domestic wells. The next
lower system, the Ludlow and Tongue River, is probably comprised
of several aquifers. The upper aquifers may be unconfined, are
interconnected with and recharge the lower part of the system.
The Upper Hell Creek and Lower Cannonbal1-Ludlou Formation form
the thiTd aquifer system and is not extensively tapped in this
area. The lowermost system, the Fox Hills and Basal Hell Creek
Formation, is not heavily used in this area but is tapped by two
Belfield city wells. The minimal water in the alluvial deposits
on the Heart River in this area may contribute to local wells.
The water table is about 40 ft below the surface.
There are four major usable aquifer systems beneath the site.
These include from highest down, the Upper Ludlow and Tongue
River Aquifer, Middle Ludlow Aquifer System, Upper Hill Creek anc
Lower Ludlow Aquifer System, and the Fox Hills and Basal Hill
Creek System. The upper three are locally interconnected, with
recharge from precipitation and seepage from surface waters and
are used locally for domestic and stock purposes. The lower
aquifer. Fox Hills and Basal Hill Creek System, is recharged by
percolation from overlying beds, is most reliable and serves
municipal needs.
Waste and Soil
Characteristics
No mill material is present; all ash from the kiln was shipped
to Sifle, CO. However, radiation measurements showed that most
of the surrounding soil at the site is contaminated to depths of
6 to 12 in, locally to 4 ft. The soils present on the site are
Savage Sllty clay loams; soil and subsoil are 2 to 3 ft thick.
Hill materials (ash from the kiln) was collected and shipped to
Grants, NH, for further processing. The soil at the site is con-
taminated to depths of about 3 ft. Soils are silts and clays up
to 7 ft in depth, with sands below that. Bedrock is not consoli-
dated and is less than 20 ft below the surface, at which depth a
coal bed is located.
-------
Table 3-2. SUMMARY DESCRIPTIONS OF INACTIVE URANIUM MILL TAILINGS SITES (confd)
Falls City, TX
Green River, UT
Location,
Topography
The site is located about 46 ni southeast of San Antonio and 10
mi southwest of Falls City, on the plain that slopes into the
Gulf of Mexico. The site is in lou, rolling hills.
The site is located 1 mi east of the city of Green River and 0.5
mi east of the Green River.
Geology
CO
The Falls City tailings and millsite are located on the Texas
Coastal Plain of the Gulf of Mexico. Bedrock at the site con-
sists of Jackson Group sandstones and interbedded strata which
dip gently to the southeast.
The site is on a slope between an upper abandoned river terrace
and the present flood plain of the Green River and its local tri-
butary, Browns Wash. The tailings rest upon the upper terrace
deposits, the alluvium of the flood plain, and upon Mancos Shale
bedrock. Approximately 1O to 25 ft of Mancos Shale underlie the
tailings area and separate it from the Dakota Sandstone and older
sedimentary units.
Surface Water The site straddles the drainage divide between the San Antonio
Hydrology River Basin to the northeast and the Nueces River Basin to the
southwest. The surface drainage near the site is ephemeral and
well above the water table within the Jackson Group strata. Tor-
rential rainfall can result in gullying and high rates of erosion
and part of the area (pond 6) is in 100-yr flood plain. Each of
the tailings ponds traps some water, and standing water is local-
ly present in each of the tailings areas. Saturated conditions
could lead to leaching and flow of leachate into ground and sur-
face waters; there are local seeps and a marshy area.
The surface waters adjacent to or near the site consist of Browns
Hash, which borders the site on the north, and the Green River,
which is 0.5 mi downstream from the tailings site. Browns Mash,
an intermittent stream, drains an area of 80 sq mi that includes
the site. Significant flooding occurs in Browns Hash, and such
floods have undercut the stream bank and eroded tailings at the
site. Contamination of the Green River could occur during flood
conditions.
Ground Hater The confined aquifers consist of waters within streambed alluvium
Hydrology and waters within the Jackson Group. Three confined aquifers are
tapped in the region: the Carrizo, Yegua, and Jackson aquifers.
Because of the ground water gradients, stratigraphic location,
and interbedded impermeable strata, there is no potential for
contamination of the Carrizo or Yegua aquifers. A potential
exists for the contamination of unconfined ground waters and the
Jackson aquifer wh'ich they recharge; however, because the water
level within Jackson bedrock is more than 2OO ft below the ground
surface, contamination of this aquifer should not be significant.
The Hancos Shale serves as a confining layer over the Dakota
Sandstone. Although the Dakota Sandstone is a potential aquifer
at Green River, it is not tapped because of its poor water qua-
lity and the availability of surface waters associated with the
Green River. The unconfined aquifers in the Green River area
consist of waters within the recent flood plain alluvium and
associated older terrace deposits.
Haste and Soil
Characteristics
The tailings consist of slimes, clay, and sand.
typical of weathered sandstone.
The soil is
The tailings are of finely-ground sand, white to pink in color.
They have a bulk density of about 92 Ib/cu ft. Alluvial mate-
rial and the Mancos Shale Formation underlie the tailings.
-------
Table 3-2. SUMMARY DESCRIPTIONS OF INACTIVE URANIUM HILL TAILINGS SITES (cont'd)
Mexican Hat, UT
Salt Lake City, UT
Location,
Topography
The site is on the Navajo Indian Reservation about 1.5 mi south-
west of Mexican Hat, UT. The site area slopes north toward the
San Juan River. The area is arid and desert like with low, rol-
ling hills and steep Hashes uhere basins have been formed by
drainage tributaries of the San Juan River.
The Vitro site is about 4 ml southwest of the Salt Lake City, UT,
downtown area.
(jO
p—'
U)
Geology
The site is situated on outcrops of the Halgaito Siltstone Tongue
of the Cutler Formation. The Halgaito Siltstone is 50 to 100 ft
thick beneath the tailings areas. Below this formation lies the
Elco Formation, which consists of nore than 3.0OO ft of alternat-
ing Siltstone, sandstone, and limestone. Neither the Halgaito
nor the Rico Fornatlons are considered to be aquifers in this
area of the Navajo Reservation.
The site is underlain by at least 500 ft of unconsolidated
Quaternary deposits with the upper 85 ft of subsoils consisting
of laterally discontinuous thinly interbedded fine sand, silty
sand, clay and silt. The upper 50 to 70 ft of the complex fora
the unconfined aquifer system. The area is seisnically active;
the N-S trending normal Hasatch Fault has had vertical displace-
ment of as ouch as 20 ft within the past 300 years.
Surface Hater
Hydrology
The tailings are situated in a wash and therefore block the nor-
mal surface drainage existing previously. Diversion channels
have been cut around the south and east sides of the tailings.
Several washes meet northeast of the lower tailings pile and lead
to the San Juan River. Surface water is found at two locations
near the site; one is a sewage pond near the mill building and
the other is a small pond in the wash northeast of the tailings.
Hill Creek, the Vitro Ditch, and the South Vitro Ditch contain
flowing surface water. The mean flows are 10, 24, and 3 cfs,
respectively. Precipitation normally collects on the tailings
and evaporates, or may percolate a few feet into the tailings.
Ground Hater The deeP ground water of the area around Mexican Hat and the
Hydrology thick Halgaito Siltstone beneath the tailings create conditions
under which ground water contamination by the tailings is highly
unlikely.
There are two water-bearing horizons beneath the Vitro area: a
lower confined artesian aquifer, and a shallow unconfined aqui-
fer. There is no downward migration of surface water Into the
artesian aquifer; consequently, no contamination of the confined
aquifer by radioactive materials at the surface has resulted.
The upper surface of the confined aquifer is located at about 70
ft below the interface of the tailings and the undisturbed soil.
The average depth to water In the unconfined aquifer In the vici-
nity of the site is 3 ft below normal ground levels, and seasonal
fluctuations are from 2 to 5 ft.
Waste and Sol 1
Character 1st ics
Sands and slimes are segregated in some areas of the Mexican Hat
tailings. Bulk densities of tailings samples range from 60 to
10O Ib/cu ft. The soil on the site is a combination of sand, red
sandstone, and outcropplngs of Siltstone.
The tailings are being relocated offsite (scheduled for comple-
tion by 1988). The site is underlain by thick- to thin-bedded
lake sediments.
-------
Table 3-2. SUMMARY DESCRIPTIONS OF INACTIVE URANIUM MILL TAILINGS SITES
Converse County, WY
Rlverton, NY
Location,
Topography
The Spook site is located approximately 32 mi northeast of
Glenrock, NY. It is located among rolling hills in the drainage
basin of the Cheyenne River. Vegetation Is comprised of sage-
brush and native grasses, ulth cottonuood trees along the creek
bottoms.
The site is located about 2.3 mi southwest of the center of
Riverton, on the Hind River Indian Reservation. The land around
the site is mainly flat and gently sloping ranch land.
Geology
The site is located on the slopes of a hillside; bedrock is ex-
posed in the open pit and consists of sandstones and shales of
the Monument Hill unit of the Hasatch Formation. The Hasatch
Formation is underlain by up to 2,000 ft of sandstones and shales
of the Fort Union Formation. The shale and claystone units of
the formations act as confining layers that prevent the upward
and dounuard migration of ground waters.
The site is on approximately 15 to 25 ft of soil and coarse-
grained alluvium of the Wind River flood plain, underlain by ap-
proximately 2.OOO ft of sedimentary Wind River Formation bedrock.
The formation consists of an interbedded sequence of lenticular
fine- to coarse-ground sandstones, siltstones, and shales with
lesser amounts of bentonlte, tuff, and limestone. These sedimen-
tary beds are nearly horizontal below the site.
Surface Water
Hydrology
(jO
H-*
•Cs
Ground Water
Hydrology
The surface waters consist of standing water in the pit during
some months of the year, an interceptor ditch that diverts storm
runoff around the tailings and pit, ephemeral drainage channels,
and an intermittent stream south of the pile known as the Dry
Fork Cheyenne River. Because of the distance of flowing surface
uJaiiia&e sy&iuia, oil-site contamination of surface waters by phy-
sical transport of tailings or by chemical leaching is unlikely.
The aquifers of the Powder River Basin System are typically at
different depths within the Uasatch and Fort Union Formations,
and water qualify and quantity vary considerably. Hells in the
area are usually completed at depths of less than 300 ft. Some
flow, others are pumped. Recently, because of reduced flow rates
in shallow wells, mining companies have developed deep wells
(greater than l.OOO ft). Regional recharge areas for the aqui-
fers are the highland areas. Local recharge areas Include higher
areas such as the Cheyenne River Divide or locations where perme-
able formations are intercepted by surface waters. The Spook
Hine pit is in permeable strata and can act as a point for ground
water recharge. However, this recharge potential Is small due to
the United precipitation that is trapped on the site. Should
contamination occur due to the tailings, the effects would be mi-
nimal. Only stock water wells tap the nearby shallower aquifers.
Flowing streams nearby Include the Little Wind River (0.5 ml SE)
and the Hind River (100 mi N). Also numerous irrigation ditches
flow near the site and empty into marshy areas near the site.
Because of the extensive flood plain, slightly elevated location
of the pile, and protection from highway road grades, flood
tailings pile, although flood waters could rise within the base
of the tailings.
The confined ground waters in the Wind River Formation occur
under very shallow as well as deeper artesian condtlons. The
shales act as confining layers to water in lenticular sandstone
horizons, but the entire sequence behaves somewhat as a single
aquifer. Intensive development of the area's ground water, in-
cluding wells on the millsite, has affected water levels, fiou
gradients, and artesian pressures In the immediate vicinity of
the city of Riverton. The ground water flow gradient is toward
the Riverton well field. Due to natural topography and return
irrigation flows, much of the area is waterlogged and evaporation
results in salt deposits in the soils. The water table at the
site is usually less than 6 ft belou the original land surface
and unconfined ground waters rise within the base of the tail-
ings.
Waste and Soil
Character!sties
The tailings are sandy in character. The soil on the site is a
thin layer of weathered sandstone from the bedrock beneath the
site.
The tailings consist of coarse and finely ground sand and slices.
The alluvial material under the tailings is composed of soil,
gravel, and cobbles.
-------
Table 3-3. METEOROLOGICAL DATA FOR INACTIVE UKANIUH MILL TAILINGS SITES
SITE NAME
Monument Valley, AZ
Tuba City, AZ
Durango, CO
Grand Junction, CO
Gunnlson, CO
May bell, CO
Natunta, CO
to
1 New Rifle, CO
h- *
*-" Old Rifle, CO
Slick Rock, CO (NO
Slick Rock, CO (UC)
Lowman, ID
Ambrosia Lake, NH
Shiprock, NH
Belfield, ND
Bowman, ND
Lakevlew, OR
Canonsburg, PA
Falls City, TX
Green River, UT
Hexican Hat, UT
Salt Lake City, UT
Converse Co. , UY
Riverton, UY
ELEV.
FT.
4900
5000
6500
4590
7635
6220
5355
5315
5315
5450
5450
4000
6980
4960
2565
3O50
4750
970
425
4080
4300
4365
5100
4950
PR
AVG/YR
8"
6'
19"
9"
11"
14"
11"
12"
12"
7"
7"
20-25"
10-
<8"
16"
15"
16"
37"
29"
6"
6"
15"
13"
10"
PRECIPITATION
AVG/YR. MAJOR STORM FREQUENCY
3.6-2.5" nax, 1-3" expected, 24hr
4" nax, 1-3" expected, 24 hr.
6hr storm of 1-3" probable every
5 seasons
6hr storm of 1" probable every
5 seasons
6hr storm of 1" probable every
5 seasons
6hr storm of 0.9" probable every
5 seasons
6hr storm of 1.1" probable every
5 seasons
max recorded 24 hr storm 1.96"
max recorded 24 hr storm 1.96"
subject to early fall thunderstorms
subject to early fall thunderstorms
heavy rainstorms once every 10 yr
24hr storm of 1.25" probable every
2 years
max recorded 24 hr storm 4"
max recorded 24hr storn 4.03" *1
max recorded 24hr storm 2.63" *1
no history available
unofficial records 10-12" yearly
hi—Intensity rainstorms common
24" during hurricane Beulah '67
24hr storm of 1" probable every
2 years
24hr storm of 1.25" probable every
2 years
hi-intensity storms
-------
Table 3-4. RADIOACTIVITY IN INACTIVE URANIUH HILL TAILINGS PILES
SITE NAME
Honuwnt Valley, AZ
Tuba City, AZ
Durango, CO
Grand Junction, CO
Gunnison, CO
Naybell, CO
Naturita, CO
New Rifle, CO
Old Rifle, CO
Slick Rock (NC), CO
Slick Rock (UC), CO
LoiMan, ID
Ambrosia Lake, NH
Shiprock, NM
Belfield, ND
BoMun, ND
XJNTOF
LINGS
,11 ions
; tons)
1.2
0.8
1.6
1.9
0.5
2.6
0
2.7
0.4
0.04
0.35
0.09
2.6
1.5
0
0
AREA OF
TAILINGS
(Acres)
30
22
21
59
39
80
(23)
32
13
19
6
5
105
72
7.5
12
AV6. RADIUM-226
ORE AVERAGE
GRADE CONCENTRATION
(XU308) (pCi/g)
0.04
0.33
0.25
0.28
0.15
0.098
Tailings
0.31
0.36
0.28
0.25
0.19
0.23
50
920
700
780
420
270
RADIUH-226
MAX. MEASURED
CONCENTRATION
(pCi/g)
1,300
1,880
1,800
1,800
1,100
600
RADIUM- RADON-222 RADON-222 RADON-222
226 ASSUMED RE- ESTIMATED RE- MEASURED RE-
(Ci) LEASE RATE LEASE RATE LEASE RATE
(Ci/y) (pCi/i s) (pCi/m s)
50
670
1,200
1,350
200
640
200
2,600
1,900
5,900
2,100
2,800
pile removed, residual contamination remains
870
1,000
780
690
530
640
0.25 700
Contaarinated soils
Contaminated soils
1,900
5,400
350
120
240
900
4,000
and Materials
and materials
2,130
320
30
70
10
1,520
950
froa off site
from off site
3,600
1,700
1,900
500
300
8,600
6,400
properties
properties
50
920
700
780
420
270
1-124
870
1,000
780
690
530
640
700
14-29
11-400
35-310
25-660
480
75-100
70-1,400
210-1,300
4-250
6-24
50-150
40-300
53-160
(440-1200-2200)
1.3-63
48-94
PROPOSED
REMEDIAL
ACTION
SIP FY87
SIP FY87
Removal started
Removal
Removal
SIP
Removal FY91
Removal
Removal
SIP (at UC)
SIPFY90
SIP
SIP FY87
SIP (done)
Move to Boman
SIP
-------
Table 3-4. RADIOACTIVITY IN INACTIVE URANIUM HILL TAILINGS PILES (confd)
SITE NAME
I
h->
^1
Lakevieti, OR
Canonsburg, PA
Falls City, TX
Green River, UT
Mexican Hat, UT
Salt Lake City, UT
Converse Co., WY
Riverton, HY
Total
AMOUNT OF AREA OF
TAILINGS TAILINGS
(Millions (Acres)
at tons)
0.13
0
2.5
0.12
2.2
0
0.19
0.9
24.42
9
68
(100)
5
72
AV6. RADIUM-226
ORE AVERAGE
GRADE CONCENTRATION
(XU308) (pCi/g)
30 0.15 420
(18) Tailings stabilize
146 0.16 450
0.29 810
0.28 784
Removal underMa
0.12 340
0.20 560
RADIUH-226 RADIUM- RADON-222 RADON-222 RADON-222
KAX. MEASURED 226 ASSUMED RE- ESTIMATED RE- MEASURED RE-
CONCENTRATION (Ci) LEASE RATE LEASE RATE LEASE RATE
(pCi/g) (Ci/y) (pCi/a s) (pCi/m s)
420 50 1,600 420 187-710
(3-31)
ily residual contain nation remains 185-296
160 1,020 8,400 450 3-78
220 20 900 810 32-128
1,900 1,560 6,800 784 16-1,600
»plete by 1988 1-20
(130-300-650)
650 60 200 340 190-2,860
1,100 544 5,100 560 50-80
PROPOSED
REMEDIAL
ACTION
Revival started
SIP
SIPFY88
SIP
SIP FY87
Reenval
SIP
S1P
-------
TABLE 3-5. AVERAGE CONCENTRATION OF ELEMENTS FOUND IN INACTIVE URANIUM MILL TAILINGS (a)
(in ppm)
u>
i
00
ELEMENT
Tailings Pile
Arizona
Monument Valley
Tuba City
Colorado
Uurango
Grand Junction
Gunnison
nay be 11
Naturita
New Kitle
Old Kifle
Slick Rock NC
Slick Kock UC
New Mexico
Ambrosia Lake
Shiprock
Utah
Green Kiver
Mexican Hat
Vitro Uranium*0'
Vitro Vanadium^0'
Wyoming
Spook
Kiverton
"Typical" Soil^"-1
As
Arsenic
1.5
82
0.80
14
254
1.5
59
4.2
3.7
34
6.6
2.6
0.004
1.9
63
210
244
87
161
6
Ba
Barium
-
86
82
121
66
18
172
100
155
453
134
96
-
73
12
2130
3860
46
64
500
Cd
Cadmium
-
4
0.20
1.6
0.26
0.09
0.07
1.1
8.7
0.027
0.074
3.6
-
0.40
0.70
_
-
0.37
0.32
0.06
Cr
Chromium
-
6
8.8
29
5.2
9.3
3.5
55
20
4.9
3.4
8
-
17
1.0
1010
2030
26
23
100
Cu
Copper
-
1160
95
14
30
3.1
54
8
18
35
17
58
-
102
488
310
1080
14
21
20
Fe
Iron
-
7230
62
1170
20800
2100
16400
807
8250
6540
4080
90
-
1210
3650
31100
213000
15299
21800
38000
Pb
Lead
—
812
62
50
137
13
48
187
38
1250
29
—
—
121
40
3060
350
2.5
3.2
10
Hg
Mercury
—
0.001
0.87
0.026
—
0.09
—
0.001
0.25
109
0.074
0.002
—
0.001
—
—
—
~~
0.03
Se
Selenium
0.064
10
1.2
3.1
1
13
0.47
1.9
2.7
0.76
2.2
68
0.18
231
6
—
--
262
391
0.2
Ag
Silver
—
6
1.2
0.72
3.8
0.15
1.1
1.4
0.46
1.7
0.57
0.15
—
0.070
1.0
0.022
0.066
2.2
2.4
0.1
U
Uranium
60
370
480
180
90
120
500
240
380
80
50
210
120
60
140
180
50
130
70
1.0
V
Vanadium
1850
620
3900
1760
80
120
2890
3990
520
620
1480
1590
330
1390
1350
100
830
350
240
100
Zn
Zinc
~
249
304
45
120
17
75
31
359
21
21
47
—
21
•57
340
350
31
38
50
Ra-226(b)
Radium
(x 10"6)
50
920
700
780
420
274
—
870
1000
780
690
640
700
810
780
900
340
560
1.5
d from G. Markos and K.J. Bush, "Physico-chemical Processes in Uranium Mill Tailings and Their Relationship to Contamination" (MacSla)
lb;TaDle 3-1 (1 pCi/g = 1 x 10~6ppm, for Ra-226).
'•'•'TWO different parts of the Vitro Site, Salt Lake City, Utah.
-------
TABLE 3-8. GROUND HATER MATRIX
SITg_GRQUNDrIIATER_CHARACTERISTICS
AREAL AND VERTICAL EXTENT
OF GROUND-HATER CONTAMINATION
co
I
NATURE AND DEGREE OF
CONTAMINATION RELATIVE TO
DRINKING HATER STANDARDS
NATURAL GROUND-HATER QUALITY
EXISTING USE OF GROUND HATER
FATE OF THE PLUME(S)
COST AND DURATION OF GROUND-
HATER RESTORATION
FEASIBILITY OF INSTITUTIONAL
CONTROLS
ALTERNATE DISPOSAL SITE
DEPTH TO HATER TABLE AT
ALTERNATE DISPOSAL SITE
HATER QUALITY AT ALTERNATE SITE
AHBROSIA_LAKEA_NM
Primarily in alluvium & Trea
Hermanos-C; may eventually dis-
charge into Hestwater Canyon.
Approximate volumes:
Alluvium - 450 million gal.
Tres H.C - 225 million gal.
Most samples exceed standards
for Co,Mn,Ho,Radium,5O4, and TDS
A small tt of sarnies exceed stds
for As,B,Cd,Cl,Cr,F,G Alpha,Fe,
NO3,pH,Se,Ag, and U.
The alluvium and Tres Hermanos-C
sandstone were probably unsat-
urated prior to mining and
mill ing.
None in alluvium & Tres Hermanos
sandstone:Hestuater Canyon sand-
stone is major water supply.
Eventual discharge to mine
shafts and vents into Uestwater
Canyon Sandstone.
No calculation.
Because only unused and unusable
grounduater has been and will be
significantly impacted there is
no need for inst. controls.
None.
N/A
N/A
BELFIELDA_ND
Sentinel Butte Formation, extent
not yet determined.
Not yet determined.
High concentration of SO4, TDS
Stock wells, some domestic
wells mostly for purposes other
than drinking.
Possible discharge to the Heart
River.
Unknown.
State of North Dakota requires
well permits for domestic wells.
Bull creek or stabilization
with tailings at Bowman, ND.
Bull Creek - 50 feet
Bowman - 1O to 15 feet
Bowman - high S04, TDS
Bull Creek - unkown, probably
similar to Belfield and Bowman
EXPECTED IMPACT ON HATER
QUALITY AT ALTERNATE SITE
NAME OF NEAREST CITY, DISTANCE
FROM TAILINGS PILE.
N/A
Grants, NM - 8 miles.
Minimal.
Belfield, ND - 1/2 mile.
-------
TABLE 3-6. GROUND NATEK MATRIX (confd)
SiIE_GIOyMprWATEH_CHAlACTIRISTICS
AREAL AND VERTICAL EXTENT
OF GROUND-HATER CONTAMINATION
NATURE AND DEGREE OF
CONTAMINATION RELATIVE TO
DRINKING HATER STANDARDS
NATURAL GROUND-HATER QUALITY
BQHHANX_ND
Tongue River Formation, extent
not yet determined.
Not yet quantified.
High concentration of SO4,TDS
CANQNSBURG^PA
Onsite in alluvium. May extend
into upper shale/limestone bed-
rock. Some indication of alight
contamination.
Volume approx. 1OO million gal.
Cosntituents above standards in
onsite, alluvial waters are:
C1,S04, and TDS.
Background alluvial water sample
NO3 exceeds standard.
EXISTING USE OF GROUND HATER
FATE OF THE PLUME(S)
Stock wells and a few domestic
wells, not normally used for
drinking.
To be determined.
Limited use, primarily for
gardening. Note: More data will be
forthcoming from S&M monitoring.
Probably discharging to Chartier
Creek although there maybe some
underflow in shallow bedrock.
u>
i
NJ
O
COST AND DURATION OF GROUND-
HATER RESTORATION
FEASIBILITY OF INSTITUTIONAL
CONTROLS
Hill be evaluated if necessary.
State of North Dakota requires
well permits for domestic wells.
Not determined.
High feasibility given limited
use & discharge of contamination
to Chartiers Creek at site bound
ALTERNATE DISPOSAL SITE
DEPTH TO HATER TABLE AT
ALTERNATE DISPOSAL SITE
HATER QUALITY AT ALTERNATE SITE
Bull Creek, approximately N/A
50 miles north of Bowman.
50 feet. N/A
Unknown, likely to be similar to N/A
the background water quality at.
Bowman and Belfield.
EXPECTED IMPACT ON HATER
QUALITY AT ALTERNATE SITE
NAME OF NEAREST CITY, DISTANCE
FROM TAILINGS SITE.
Minimal.
Bowman, ND - 7 miles.
N/A
Canonsburg, PA - in town.
-------
TABLE 3-6. GROUND WATER MATRIX (confd)
AND VERTICAL EXTENT
OF GROUND-HATER CONTAMINATION
to
NATURE AND DEGREE OF
CONTAMINATION RELATIVE TO
DRINKING HATER STANDARDS
NATURAL GROUND-HATER QUALITY
EXISTING USE OF GROUND HATER
FATE OF THE PLUHE(S)
COST AND DURATION OF GROUND-
WATER RESTORATION
FEASIBILITY OF INSTITUTIONAL
CONTROLS
ALTERNATE DISPOSAL SITE
DEPTH TO HATER TABLE AT
ALTERNATE DISPOSAL SITE
HATER QUALITY AT ALTERNATE SITE
EXPECTED IMPACT ON HATER
QUALITY AT ALTERNATE SITE
NAME OF NEAREST CITY, DISTANCE
FROM TAILINGS SITE
DURANGOi_CO
DURO1 (piles) - alluvium: approx-
50 acres x 20-3O feet deep.
DURO2 (ponds) - alluvium approx-
55 acres x 3O-4O feet deep.
Henefee Fm. one well 5O-7O* deep
DURO1 - alluvium: CL-4x, Fe-2x,
As-lOOx,Se-lOOx,SO4-15x,U(6.2mg/
DUR02 - alluvium: Cl-5x,As-5x,
Se-40x, S04-115X, U(2.4mg/L)
DURO2 - Menefee Fm: Cl-6x, Se-2x
slightly elevated Cl, Fe, TDS, U
but drinking water quality
No current users within two
miles downgradient.
Discharge to Aninas River within
100 to 500 feet of the piles and
ponds.
Not evaluated.
Have been recommended to the
state.
Bada Canyon
20 to 40 feet
S04, TDS, Fe, Mn exceed
drinking water standards.
Minimal; shallow system
discharges to Animas River
within two miles of the site.
Durango, Colorado -
1.5 miles NE of Bada Canyon site
Unconfined system (Dewesville/
Conquista) TOO ac x 60-7O feet.
approx. 4 billion gallons.
Semi-confined (Dilworth):
contamination in 2-4 wells, 12O
to 15O feet deep.
Unconfined system: Cl-23x,Fe-4Ox
Mn-20Ox,SO4-2OX,TDS-26x,Ra-226
( 100pci/L),U(67mg/L)
Semi-confined system: Cl-4x,
S04-8x,TDS-15x,U(3.2mg/L).
SO4,Cl,Fe,Mn,TDS exceed drinking
water stds, U= 1OO-3OO ppb.
Four livestock wells within two
miles. No domestic consumption.
Discharge to*San Antonio R. NE
of site in 15O to 200 years.
Discharge to Borrego Cr. SH of
site in 300 to 4OO years.
Not evaluated.
State of Texas requires well
permits for domestic wells.
Not evaluated.
N/A
N/A
N/A
Falls City, Texas
of tailings site.
- 9 miles NE
-------
TABLE 3-6. GROUND HATES HATEIX (cont'd)
S!TE_GR9yND-HATEK_CHARACTEKlSTiCS
AKEAL~AND~viiTICAL~IXTENT
OF GROUND-WATER CONTAMINATION
NATURE AND DEGREE OF
CONTAMINATION RELATIVE TO
DRINKING WATER STANDARDS
NATURAL GROUND-WATER QUALITY
EXISTING USE OF GROUND WATER
Fro» the site to the west, up to
1/2 mi doungradient of site in
alluvium. Some cntmts. may enter
Dakota Ss 8 subcrop 1/2 ui vest.
Relative to stds and background,
the 5 critical contaminants are:
Cl,F,Fe,S04, and Cd.
Most background samples exceed
standards for Cl,Fe,Hn,S04,& TDS
No known use of alluvial or
Dakota sandstone Hater.
Brown's Wash Alluvium - <= 9 ac
x 7 feet
Cedar Mountain Fm. - <= 9 ac
x 25 feet.
Alluvium - N03-lix, NH4(4Dmg/L),
U( 1.19mg/L),Mn-lOx.
Cedar Mtn. Fm. - N03-llx,
NH4(30»g/L), U( 1,86mg/L),
Mn-25x
Not suitable for drinking water.
High cone, of TDS, S04, Cl, Se, F.
None.
FATE OF THE PLUME(S)
uo
I
to
to
COST AND DURATION OF GROUND-
WATER RESTORATION
FEASIBILITY OF INSTITUTIONAL
CONTROLS
ALTERNATE DISPOSAL SITE
DEPTH TO WATER TABLE AT
ALTERNATE DISPOSAL SITE
Discharge to the Colorado River
or enter the Dakota SS and dis-
perse through space and time.
Initial estimates at least
$1 million over at least 2 yrs.
Highly feasible: l)The site is
w/in a municipality. 2)Contamin-
ated water has not been used &
has limited value.
Cheney Reservoir
Approximately 3O feet.
Alluvium - discharge into Brown's
Wash approx 4OO feet from pile.
Cedar Mtn. Fm. - no discharge
point identified. Plume will
disperse in this aquifer.
Not evaluated.
State of Utah requires well
permits for domestic use.
Recommended stabilization on site
N/A
WATER QUALITY AT ALTERNATE SITE
EXPECTED IMPACT ON WATER
QUALITY AT ALTERNATE SITE
NAME OF NEAREST CITY, DISTANCE
FROM TAILINGS SITE
Brackish. Seasonally perched.
No impact on any potential water
resource.
Grand Junction, CO - in town.
N/A
N/A
Green River, UT
of site.
- 1 mile NW
-------
TABLE 3-6. GROUND HATER MATRIX (confd)
i
K3
U>
ARBAL AND VERTICAL EXTENT
OF GROUND-WATER CONTAMINATION
NATURE AND DEGREE OF
CONTAMINATION RELATIVE TO
DRINKING WATER STANDARDS
NATURAL GROUND-WATER QUALITY
EXISTING USE OF GROUND WATER
FATE OF THE PLUHE(S)
COST AND DURATION OF GROUND-
WATER RESTORATION
FEASIBILITY OF INSTITUTIONAL
CONTROLS
ALTERNATE DISPOSAL SITE
DEPTH TO WATER TABLE AT
ALTERNATE DISPOSAL SITE
WATER QUALITY AT ALTERNATE SITE
EXPECTED IMPACT ON WATER
QUALITY AT ALTERNATE SITE
NAME OF NEAREST CITY, DISTANCE
FROM TAILINGS PILE
approximately 1 sq. Bile;
10O ft.
Disperse & dilute as the
contaminants move downgradient
in the unconsolidated deposits.
Not evaluated.
The contaminant levels are low
enough that only shallow ground
water close to the site may need
to be controlled. Therefore
institution controls are feasible
Collins Ranch.
Greater than 30 feet.
Potable without treatment.
Minimal impact; i.e.,stds should
not be exceeded at closest well
for at least 1000 yrs.
Lakeview, OR - in town.
-------
TABLE 3-6. GROUND HATES MATRIX (confd)
CHARACTERISTICS
AREAL AND VERTICAL EXTENT
OF GROUND-HATER CONTAMINATION
To be determined.
HAYBELL^CQ
To be determined in FY87.
i
ro
NATURE AND DEGREE OF
CONTAMINATION RELATIVE TO
DRINKING HATER STANDARDS
NATURAL GROUND-HATER QUALITY
EXISTING USE OF GROUND HATER
To be determined.
FATE OF THE PLUME(S)
COST AND DURATION OF GROUND-
HATER RESTORATION
FEASIBILITY OF INSTITUTIONAL
CONTROLS
ALTERNATE DISPOSAL SITE
DEPTH TO HATER TABLE AT
ALTERNATE DISPOSAL SITE
HATER QUALITY AT ALTERNATE SITE
EXPECTED IMPACT ON HATER
QUALITY AT ALTERNATE SITE
NAME OF NEAREST CITY, DISTANCE
FROM TAILINGS PILE
Drinking water quality
TDS < 250 »g/L.
Surface and ground water used
for drinking water supplies.
To be determined.
Hill be evaluated if necessary.
To be determined.
Possibly along Highway 21, east
of the tailings, not yet
positively identified.
Unknown.
Unknown, probably similar to
Lowman.
Unknown.
Lowman, Idaho - 1/4 mile.
U, N03, S04, Cl, and possibly
trace elements (As, Se, Ho) are
constituents of tailings seepage
Site hydrogeological conditions
are not complete & solutes that
exceed Standards not yet known.
Possible drinking water quality.
TDS as high as 12OO mg/L.
Ground water within the alluvium
used for drinking water supply
in Maybell. Browns Park Fm. is a
regional source of drinking
water supply.
To be determined.
Hill be evaluated if necessary.
State of Colorado requires well
permits for domestic wells.
Johnson Pit - located approx.
O.25 mile south of tailings site.
Unknown.
Unknown, possibly similar to
Haybell.
Unknown.
Haybell, CO - 7.3 miles SH.
-------
TABLE 3-6. GROUND HATER MATRIX (cont'd)
I
NJ
Ln
SITE_GRgyNDrHATEK_CHAKACTERISTICS
AREAL AND VERTICAL~EXTBNT
OF GROUND-WATER CONTAMINATION
NATURE AND DEGREE OF
CONTAMINATION RELATIVE TO
DRINKING HATER STANDARDS
NATURAL GROUND-HATER QUALITY
EXISTING USE OF GROUND HATER
FATE OF THE PLUME(S)
COST AND DURATION OF GROUND-
HATER RESTORATION
FEASIBILITY OF INSTITUTIONAL
CONTROLS
ALTERNATE DISPOSAL SITE
DEPTH TO HATER TABLE AT
ALTERNATE DISPOSAL SITE
HATER QUALITY AT ALTERNATE SITE
EXPECTED IMPACT ON HATER
QUALITY AT ALTERNATE SITE
NAME OF NEAREST CITY, DISTANCE
FROM TAILINGS PILE
30O acres x 4O feet.
Mn-26x,NO3-2X,S05-9x,TDS-Bx
UCO.43 mg/L)
High cone, of SO4 and TDS;
unsuitable for drinking water.
None.
Seepage into Gypsum wash and
movement to San Juan R. No
contamination in the river.
Not evaluated.
Navajo Tribe requires well
permits for domestic wells.
Not evaluated.
N/A
N/A
N/A
Mexican Hat, Utah - one mile.
Halchita, Utah - 0.25 miles.
HONUMENT_yALLEYi_AZ
570 acres x 80 feet.
N03-24x,S04-6x,U(0.03 »g/L)
Mn-12x,TDS-7x
Drinking water quality
TDS < 500 mg/L.
A few handpump wells for local
residents.
Natural dispersion, 2O to 20O yr
to reach background. Possibly
some discharge to Cane Valley
Hash during storms.
25 to 5O years, *1OH to »25M.
Navajo Tribe approves/records
all welIs.
Yazzie Mesa approx. 1/2 mile
southwest of the tailings.
160 feet.
Drinking water quality
TDS < 5OO mg/L.
Minimal; water table separated
from tailings by relatively
impermeable Hoenkopi Formation.
Mexican Hat, Utah.
-------
TABLE 3-6. GROUND HATES HATSIX (cont'd)
u>
i
NJ
S1TE_GROUNDZHATER CHARACTERISTICS
AR!AL~AND VERTICAL IXTENT
OF GROUND-HATER CONTAMINATION
NATURE AND DEGREE OF
CONTAMINATION RELATIVE TO
DRINKING HATER STANDARDS
NATUR1TA±_CO
Alluvium - 73 ac x 20 feet.
95 million gallons.
Fe-3x,Hn-65x,S04-4x,
TDS-4x,U(2.5mg/L)
NATURAL GROUND-HATER QUALITY
EXISTING USE OF GROUND WATER
FATE OF THE PLUHE(S)
COST AND DURATION OF GROUND-
WATER RESOTRATION
FEASIBILITY OF INSTITUTIONAL
CONTROLS
ALTERNATE DISPOSAL SITE
DEPTH TO HATER TABLE AT
ALTERNATE DISPOSAL SITE
HATER QUALITY AT ALTERNATE SITE
EXPECTED IMPACT ON HATER
QUALITY AT ALTERNATE SITE
NAME OF NEAREST CITY, DISTANCE
FROM TAILINGS PILE
Marginally suitable for drinking
water. SO4 and TDS slightly
above standards.
None.
Discharge into adjacent San
Miguel River.
Not evaluated.
State of Colorado requires well
permits for domestic wells.
Not evaluated.
N/A
N/A
N/A
Naturita, Colorado - 2 miles.
RFO - alluvium, 9 ac x 30 feet
RFN - alluvium, 400 ac x 3O feet
RFN - Hasatch Fm., 150 ac x 50 ft.
RFO - alluvium S04-10x; TDS-lOx?
U (2.08 mg/L)
RFN - alluvium N03-19x; S04-100x
TDS-SOx; U(1.3mg/L)i Mo(12.0mg/L
NH4C6100 mg/L)
RFN - Wasatch S04-104xi N03-2x;
TDS-76x; NH4(2900 mg/L); U(O.76
Ho(5 mg/L)
High cone, of S04, Hn, Fe,
NH4, Cl, TDS. Unsuitable for
drinking water.
Wasatch aquifer not used.
Alluvial sq. used for livestock
and irrigation. City uses
Colorado River water.
Natural seepage to river adjacent
to both sites. Return to backgrn
in a minimum of 2yrs for RFO and
45yrs for alluvium at RFN.
Plume capture by -trenching and
water capture for a minimum of
five years. Cost approx. *18H.
State of Colorado requires well
permits for domestic wells.
Estes Gulch, ground water not
used in a 2 mi. radius of site.
> 280 feet through Hasatch.
Unknown.
None. 800 yr travel time to
first possible ground water.
Rifle, Colorado - Tailings
adjacent to city.
-------
TABLE 3-6. GROUND WATER MATRIX (confd)
oo
I
to
SITE^GROUND-HATBR CHARACTERISTICS
ARBAL AND vlRTICAL~IxTENT
OF GROUND-HATER CONTAMINATION
NATURE AND DEGREE OF
CONTAMINATION RELATIVE TO
DRINKING HATER STANDARDS
NATURAL GROUND-HATER QUALITY
EXISTING USE OF GROUND HATER
FATE OF THE PLUHE(S)
COST AND DURATION OF GROUND-
HATER RESTORATION
FEASIBILITY OF INSTITUTIONAL
CONTROLS
ALTERNATE DISPOSAL SITE
DEPTH TO HATER TABLE AT
ALTERNATE DISPOSAL SITE
HATER QUALITY AT ALTERNATE SITE
EXPECTED IMPACT ON HATER
QUALITY AT ALTERNATE SITE
NAME OF NEAREST CITY, DISTANCE
FROM TAILINGS PILE
From site to the Little Hind
river(approx.1/2 Bile) through
the alluvium & unconfined SS
(approx. 20 ft thick).
Volume approx. 1 billion gal.
Key contaminants u/ exceedence
of stds are Fe,Mn,S04,Cl,and a
feu samples of exceedences for
radium and selenium. U as high
as 2 mg/L, & Mo max is 4 mg/L.
Brackish in alluvium.
Minor stock watering.
Discharge to Little Hind River.
$44 million over 20 years.
High feasibility because limited
use or potential use of alluvial
ground water.
American Nuclear Corporation in
Gas Hills.
Unknown.
Unknown.
Unknown.
Riverton, HY - 3 miles.
From site possibly to the Jordan
River and Hill Creek in the
unconfined aquifer to depth of
approx. 3O to 4O feet.
Volume approx. 1.5 billion gal.
Key contaminants are: As, Cl,
Fe, H04, TDS, and Gross Alpha.
None in unconfined system.
Discharge tot he Jordan River
and Mill Creek.
$18 - $2O million.
High feasibility due to lack of
existing & potential use and
availability of public water
supply.
Cllve, Utah.
Approximately 3O to 40 feet.
Brackish.
None on potential water resource.
South Salt Lake - in town.
-------
TABLE 3-6. GROUND NATES MATRIX (cont'd)
I
to
CO
SITE GROUND-MATER CHARACTERISTICS
ARBAL~AND~viRfTcAL~EXTiNT
OF GROUND-MATER CONTAMINATION
NATURE AND DEGREE OF
CONTAMINATION RELATIVE TO
DRINKING MATER STANDARDS
NATURAL GROUND-HATER QUALITY
EXISTING USE OF GROUND HATER
FATE OF THE PLUME(S)
COST AND DURATION OF GROUND-
WATER RESTORATION
FEASIBILITY OF INSTITUTIONAL
CONTROLS
ALTERNATE DISPOSAL SITE
DEPTH TO HATER TABLE AT
ALTERNATE DISPOSAL SITE
HATER QUALITY AT ALTERNATE SITE
EXPECTED IMPACT ON HATER
QUALITY AT ALTERNATE SITE
NAME OF NEAREST CITY, DISTANCE
FROM TAILINGS PILE
SHIPROCK±_NM
Beneath site & below site in
floodplain alluvium. Depth is 10
to 30 ft, to top of competent
Mancos Shale. Floodplain vol.
Onsite approx. 850 Billion gal.
Significant exceedences of stds
for Cl,Cr,Hn,N03,Se,S04,and TDS,
U(3.5 mg/L).
On escarpment, poor to non-
existent; on floodplain, slight
exceedence of S04 & TDS stds.
Some domestic use and potential
municipal use of floodplain
ground water and San Juan River
water.
Appears to be relatively stag-
nant but eventually should dis-
charge to the San Juan River.
Not determined.
Could be fenced, plus the
Navajo Tribe has a well permit
requirement.
N/A
N/A
N/A
N/A
Shiprock, NM - in town.
NC Site - 23 acres x 20 feet.
30 million gallons.
UC Site - 17 acres x 2O feet.
23 million gallons.
NC site: Fe-9x,Mn-9x,S04-5x,
TDS-5x,U(2.5mg/L)
UC site: N03-34x,Cl-l.lx,Fe-8x,
Hn-51x,S04-7x,TDS-Bx,
U(0.09 mg/L).
Alluvium - high cone, of Hn, S04
TDS. Not drinking water quality.
Navajo Ss. - drinking water qual.
No use of alluvial ground water.
Navajo aquifer supplies all
needs.
Discharge into adjacent Dolores
River.
Not evaluated.
State of Colorado requires well
permits for domestic wells.
Disappointment Valley.
approx. 40 feet below land
surface in Mancos Shale.
High TDS reported. Unsuitable
for drinking water.
Not evaluated.
Naturita, CO - approx 46 miles.
-------
TABLE 3-6. GROUND WATER MATRIX (cont'd)
i
NJ
AREALAND VERTICAL EXTENT
OF GROUND-HATER CONTAMINATION
NATURE AND DEGREE OF
CONTAMINATION RELATIVE TO
DRINKING WATER STANDARDS
NATURAL GROUND-WATER QUALITY
EXISTING USE OF GROUND WATER
FATE OF THE PLUME(S)
COST AND DURATION OF GROUND-
WATER RESTORATION
FEASIBILITY OF INSTITUTIONAL
CONTROLS
SPOOKi_WY
To be determined in 1987.
To be determined in 1987.
Drinking uater quality.
Domestic, agricultural, and
livestock use.
To be determined in 1987.
Will be evaluated if necessary.
State of Wyoming.
o acres x lO feet of the
Navajo Sandstone.
Approx. 1.2 billion gallons.
N03-34X5 S04-9x; U-0.45 mg/L;
Fe-2x; Mn-13x; TDS-12x.
Drinking uater quality.
TDS < 500 mg/L.
Municipal well field for Tuba
City is 5 mi. from site. One
domestic uell is 1.5 mi. cross-
gradient.
Discharge to Moenkopi Wash
1O,OOO feet from leading edgee
of plume. First arrival of
pluae at Wash in 100 years.
*6H to *37H. 15 to 20 years.
Navajo Tribe approves/records
all wells.
ALTERNATE DISPOSAL SITE
DEPTH TO WATER TABLE AT
ALTERNATE DISPOSAL SITE
WATER QUALITY AT ALTERNATE SITE
EXPECTED IMPACT ON WATER
QUALITY AT ALTERNATE SITE
NAME OF NEAREST CITY, DISTANCE
FROM TAILINGS PILE
None.
N/A
N/A
N/A
None.
N/A
N/A
N/A
Douglas, WY - approx. 45 miles. Tuba City, AZ - approx. 5 miles.
-------
REFERENCES
1. Ford, Bacon & Davis Utah, Inc. April 1981. Engineering Assessment of
Inactive Uranium Mill Tailings - Vitro Site, Salt Lake City Utah.
DOE/UMT-0102, prepared for the U.S. Department of Energy by Ford, Bacon &
Davis Utah, Inc., Salt Lake City, Utah.
2. Ford, Bacon & Davis Utah, Inc. June 1981. Engineering Assessment of
Inactive Uranium Mill Tailings - Durango Site, Durango, Colorado.
DOE/UMT-0103, prepared for the U.S. Department of Energy by Ford, Bacon &
Davis Utah, Inc., Salt Lake City, Utah.
3. Ford, Bacon & Davis Utah, Inc. July 1981. Engineering Assessment of
Inactive Uranium Mill Tailings - Grand Junction Site, Grand Junction,
Colorado.DOE/UMT-0105, prepared for the U.S. Department of Energy by
Ford, Bacon & Davis Utah, Inc., Salt Lake City, Utah.
4. Ford, Bacon & Davis Utah, Inc. July 1981. Engineering Assessment of
Inactive Uranium Mill Tailings - Naturita Site, Naturita, Colorado.
DOE/UMT-0112, prepared for the U.S. Department of Energy by Ford, Bacon &
Davis Utah, Inc., Salt Lake City, Utah.
5. Ford, Bacon & Davis Utah, Inc. July 1981. Engineering Assessment of
Inactive Uranium Mill Tailings - Shiprock Site, Shiprock. New Mexico.
DOE/UMT-0104, prepared for the U.S. Department of Energy by Ford, Bacon &
Davis Utah, Inc., Salt Lake City, Utah.
6. Ford, Bacon & Davis Utah, Inc. August 1981. Engineering Assessment of
Inactive Uranium Mill Tailings - New and Old Rifle Sites, Rifle,
Colorado^DOE/UMT-0108, prepared for the U.S. Department of Energy by
Ford, Bacon & Davis Utah, Inc., Salt Lake City, Utah.
7. Ford, Bacon & Davis Utah, Inc. August 1981. Engineering Assessment of
Inactive Uranium Mill Tailings - Riverton Site, Riverton, Wyoming.
DOE/UMT-0106, prepared for the U.S. Department of Energy by Ford, Bacon &
Davis Utah, Inc., Salt Lake City, Utah.
8. Ford, Bacon & Davis Utah, Inc. September 1981. Engineering Assessment of
Inactive Uranium Mill Tailings - Gunnison Site, Gunnison, Colorado.
DOE/UMT-0107, prepared for the U.S. Department of Energy by Ford, Bacon &
Davis Utah, Inc., Salt Lake City, Utah.
9. Ford, Bacon & Davis Utah, Inc. September 1981. Engineering Assessment of
Inactive Uranium Mill Tailings - Lowman Site, Lowman, Idaho. DOE/UMT-
0118, prepared for the U.S. Department of Energy by Ford, Bacon & Davis
Utah, Inc., Salt Lake City, Utah.
10. Ford, Bacon & Davis Utah, Inc. September 1981. Engineering Assessment of
Inactive Uranium Mill Tailings - Maybell Site, Maybell, Colorado.
DOE/UMT-0116, prepared for the U.S. Department of Energy by Ford, Bacon &
Davis Utah, Inc., Salt Lake City, Utah.
3-30
-------
11. Ford, Bacon & Davis Utah, Inc. September 1981. Engineering Assessment of
Inactive Uranium Mill Tailings - Mexican Hat Site, Mexican Hat, Utah.
DOE/ UMT-0109, prepared for the U.S. Department of Energy by Ford, Bacon &
Davis Utah, Inc., Salt Lake City, Utah.
12.
Ford, Bacon & Davis Utah, Inc. September 1981. Engineering Assessment of
Inactive Uranium Mill Tailings - Slick Rock Sites, Slick Rock, Colorado.
DOE/UMT-0115, prepared
Davis Utah, Inc., Salt
for the U.S. Department of
Lake City, Utah.
Energy by Ford, Bacon &
13. Ford, Bacon & Davis Utah, Inc. September 1981. Engineering Assessment of
Inactive Uranium Mill Tailings - Tuba City Site, Tuba City, Arizona.
DOE/UMT-0120, prepared for the U.S. Department
Davis Utah, Inc., Salt Lake City, Utah.
^
by
of Energy by Ford, Bacon &
14. Ford, Bacon & Davis Utah, Inc. October 1981 _
Inactive Uraniupi Mill Tailings - Falls City Site
Engineering Assessment of
Falls City, Texas.
DOE/UMT-0111, prepared
Davis Utah, Inc., Salt
for the U.S. Department of
Lake City, Utah.
Energy by Ford , Bacon &
15.
Ford, Bacon & Davis Utah, Inc. October 1981. Engineering Assessment of
Inactive Uranium Mill Tailings - Lakeview Site," Lakeview, Oregon.
DOE/UMT-0110, prepared
Davis Utah, Inc., Salt
for the U.S. Department
Lake City, Utah.
16.
Ford, Bacon & Davis Utah, Inc. October 1981
Inactive Uranium Mill Tailings - Monument Valley Site
of Energy by Ford, Bacon &
Engineering Assessment of
Monument Valley,
Arizona. DOE/UMT-0117, prepared for
Ford, Bacon & Davis Utah, Inc., Salt
the U.S. Department
Lake City, Utah.
of Energy by
17. Ford, Bacon & Davis Utah, Inc. October 1981. Engineering Assessment of
Inactive Uranium Mill Tailings - Philips/United Nuclear Site, Ambrosia
Lake, New Mexico.DOE/UMT-0113, prepared for the U.S. Department of
Energy by Ford, Bacon & Davis Utah, Inc., Salt Lake City, Utah.
18. Ford, Bacon & Davis Utah, Inc. October 1981. Engineering Assessment of
Inactive Uranium Mill Tailings - Spook Site, Converse County, Wyoming.
DOE/UMT-0119, prepared for the U.S. Department of Energy by Ford , Bacon &
Davis Utah, Inc., Salt Lake City, Utah.
19. Ford, Bacon & Davis Utah, Inc. November 1981. Engineering Assessment of
Inactive Uranium Mill Tailings - Belfield Site, Belfield, South Dakota.
DOE/UMT-0122, prepared for the U.S. Department of Energy by Ford, Bacon &
Davis Utah, Inc., Salt Lake City, Utah.
20. Ford, Bacon & Davis Utah, Inc. November 1981. Engineering Assessment of
Inactive Uranium Mill Tailings - Bowman Site, Bowman, South Dakota.
DOE/UMT-0121, prepared for the U.S. Department of Energy by Ford, Bacon &
Davis Utah, Inc., Salt Lake City, Utah.
3-31
-------
21. Douglas, Richard L. , and Joseph M. Hans, Jr. August 1975. Gamma
E5diation_Sur veys_at_ I^nact i ye_Uranium_MiL]1^ _Site s . ORP/LV-7 5-5 ,
prepared for the U.S. Environmental Protection Agency, Office of
Radiation Programs — Las Vegas Facility, Las Vegas, Nevada.
22. Young, J.K., L.W. Long and J.W. Reis. April 1982. Environmental.
Factors_Af f ect ing_Long-X?.IirQ_St£bi^l^i_zat1i on_of _Radon__Sup_p_ression
Cover s_f or_Uran i^um_Mi^l ]^_TailLiLngs . NUREG/CR-2564 , prepared for the
U.S. Nuclear Regulatory Commission by Pacific Northwest Laboratory,
Richland, Washington.
23. Pacific Northwest Laboratory. January 1984. Est i^mat_ed_Pop_ulLat ^on
NeSE_Ur:anium_Tailings. PNL-4 959/UC-70 , prepared for the U.S.
Environmental Protection Agency by Pacific Northwest Laboratory,
Richland, Washington.
24. U.S. EPA. October 1982. E.LQ.i.L.-l-QY.Lll'SQ.IQtQ.tal __ l?5£§.£t _Statement_f or
Remedi_al__Act L2Q._5.tandards_f or_I_nact i_ve_Uran i.y.IU_Pr.ocessi^ng_S^tes
11Q.CFR192)_. EPA-520/4/82/0 13-1 , "Off ice of Radiation Programs, EPA,
Washington, D.C.
25. U.S. DOE. January 7, 1987. Uranium_Mil.l._Tai.li.ng.s_Remedi.al._Acti.on
Pro j.ect_Ground
3-32
-------
CHAPTER 4
COMPILATION AND ANALYSIS OF GROUNDWATER DATA FOR 12 SITES
4.1 INTRODUCTION:
Groundwater quality data for 12 Uranium Mill Tailings
Remedial Action (UMTRA) Project sites are analyzed in this
chapter. The 12 UMTRA sites are:
1. Ambrosia Lake, New Mexico
2. Canonsburg, Pennsylvania
3. Durango, Colorado
4. Grand Junction, Colorado
5. Gunnison, Colorado
6. Lakeview, Oregon
7. Mexican Hat, Utah
8. Monument Valley, Arizona
9. Riverton, Wyoming
10. Salt Lake City, Utah
11. Shiprock, New Mexico
12. Tuba City, Arizona
This task analyzes the groundwater quality data collected
from wells on the sites and from wells surrounding the
sites. These data have been compared to the standards given
or referenced in Table A of 40 CFR 192.32(a), which are as
follows:
Constituent Maximum Concentration
Arsenic 0.05 mg/1
Barium 1.0 mg/1
Cadmium 0.01 mg/1
Chromium 0.05 mg/1
Gross Alpha Particle 15.0 pCi/1
Activity (including radium-226
but excluding radon and
uranium)
Lead 0.05 mg/1
Mercury 0.002 mg/1
Combined radium-226 5.0 pCi/1
and radium-228
Selenium 0.01 mg/1
Silver 0.05 mg/1
These comparisons are in Table 1 for each of the 12 sites.
4-1
-------
In addition to the constituents listed above, six pesticides
were also referenced in 40 CFR 192.32 (a). No water quality
comparisons were performed for endrin, lindane,
methoxychlor, toxaphene, 2,4-D, or 2,4,5, TP. Water samples
from the 12 sites were rarely analyzed for these pesticides.
These pesticides were undetected in the occasional samples
that were analyzed.
Three additional water quality comparisons beyond those in
Table A of 40 CFR 192.32(a), but related to leachate from
uranium mill tailings, are:
Constituent Maximum Concentration
Molybdenum 0.10 mg/1
Uranium 30 pCi/1 (0.044 mg/1)
Nitrate (nitrogen) 10 mg/1
These comparison are in Table 2 for each of the 12 sites.
Also in Table 2 are comparisons to EPA primary and secondary
drinking water standards not contained in Table 1.
A summary of the water quality data has been prepared for
each site. The tabular data are presented after each site
summary. The site summaries discuss the key contaminants
and their significance of occurrence within the context of
the site hydrogeologic setting and local groundwater use.
The fate of the contaminant plume was modeled at 9 of the 12
sites. The results indicate natural reduction of the mobile
contaminants (nitrates, chlorides, sulfates, and total
dissolved solids) to standards or background levels in 100
years or less at 6 of the 9 sites modeled. The longest
period indicated was for the Mexican Hat site where over 500
years will be required for natural flushing of the mobile
contaminants. Purging of the attenuated contaminants
(uranium, molybdenum, and other metals) typically takes 2 to
3 times as long and only at one site are levels predicted to
reach standards or background levels within 100 years. At 6
of the sites it appears that purging of these may be accom-
plished within 300 years.
4-2
-------
4.2 AMBROSIA LAKE, NEW MEXICO - SUMMARY OF WATER QUALITY
The saturated formations at the Ambrosia Lake site include
the alluvium, Tres Hermanos Sandstones, Dakota Sandstona and
Westwater Canyon Sandstone. Prior to mining and milling
activities, it appears that the alluvium and Tres Hermanos-C
Sandstone were unsaturated. Their current saturation is
believed to be a result of mine water discharges and perco-
lation from tailings slurry water.
The alluvium and Tres Hermanos Sandstone are not currently
used as a water supply source. The Westwater Canyon Sand-
stone is presently a major water supply formation. Contami-
nated water in the Tres Hermanos-C Sandstone may eventually
flow into the Westwater Canyon Sandstone via the Ann Lee
Mine shaft or other mine shafts or vents.
Groundwater quality data were analyzed for the alluvium,
Tres Hermanos Cl and C2 Sandstone and from beneath saturated
uranium mill tailings present on the site. The alluvium
data include background, upgradient, cross-gradient, on-site
and down gradient samples. The Tres Hermanos-Cl Sandstone
data are from only down gradient samples. The Tres
Hermanos-C2 Sandstone data are from cross-gradient and down
gradient samples.
Levels for arsenic, cadmium, chromium, gross alpha, radium,
selenium, and silver exceeded the standards in some samples.
Chromium concentrations were higher in on-site and down
gradient samples in the tailings, alluvium and Tres Hermanos
Sandstones than in background or cross-gradient samples.
Twenty four out of 68 analyses for selenium exceeded the
limits for the standard; concentrations are highest in the
background and upgradient alluvium. Radium concentrations
from samples in the on-site tailings and alluvium were
substantially higher than in background, upgradient,
cross-gradient or down gradient samples. The one upgradient
sample analyzed for gross alpha exceeded the standard by
more than a factor of 15.
The contaminated water in the alluvium and Tres Hermanos
Formation is draining into mine shafts and vents, mixing
with groundwater in the Westwater Canyon Sandstone. Model-
ing indicates that contaminants are dispersed in the
Westwater Canyon Sandstone within 400 feet of the mixing
zone and that drainage and dilution of the contaminated
water will be completed in about 100 years.
4-3
-------
TABLE 1
Site Name: Ambrosia Lake (New Mexico)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 06/25/80 to 01/09/87
Page 1 of 6
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Arsenic 0.05 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Barium 1 . 0 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Number of Maximum
Analyses Percent Value
Formation of Number of Exceeding Exceeding Obtained
Completion Analyses Standard Standard (mg/1) I/
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C 2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
C 1 Sandstone
Tres Hermanos-
C 2 Sandstone
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C 2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
C 1 Sandstone
Tres Hermanos-
C 2 Sandstone
8 1 12 0.18
4
2
2
18 15 0.33
12
3
12
7
1
2
1
J. *••••• —~mm • •«
7
10
2
8
3
4-4
-------
TABLE 1
Site Name: Ambrosia Lake (New Mexico)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 06/25/80 to 01/09/87
Page 2 of 6
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Cadmium 0.01 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Chromium 0 . 05 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Formation of Number of
Completion Analyses
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C 2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
C 1 Sandstone
Tres Hermanos-
C 2 Sandstone
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C 2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
C 1 Sandstone
Tres Hermanos-
C 2 Sandstone
7
4
1
2
16
12
3
12
7
7
4
1
2
16
12
3
12
7
Number of Maximum
Analyses Percent Value
Exceeding Exceeding Obtained
Standard Standard (mg/1) I/
___ ___ ___
1 6 0.10
___ _ — ___
._.
___ ___ — — —
2 12 0.20
1 8 0.10
1 33 0.17
1 8 0.21
2 28 0.11
4-5
-------
TABLE 1
Site Name: Ambrosia Lake (New Mexico)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 06/25/80 to 01/09/87
Page 3 of 6
Standard Hydraulic Flow
Constituent (ng/1) I/ Relationship
Gross Alpha 15.0 pCi/1 Background
(excluding radon Upgradient
and uranium) Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Lead 0.05 Background
Upgradient
Cross -gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Formation of Number of
Completion Analyses
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C 2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
C 1 Sandstone
Tres Hermanos-
C 2 Sandstone
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C 2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
C 1 Sandstone
Tres Hermanos-
C 2 Sandstone
1
2 2/
1
1
1 3/
1
1
1 3/
1
1
2
1
1
7
10
2
8
3
Number of Maximum
Analyses Percent Value
Exceeding Exceeding Obtained
Standard Standard (mg/1) I/
1 100 251.72
3/ 3/ 3/
3/ 2/ 3/
...
— — - — — — — —
4-6
-------
TABLE 1
Site Name: Ambrosia Lake (New Mexico)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 06/25/80 to 01/09/87
Page 4 of 6
Constituent
Mercury
Ra-226 +
Ra-228
(Radium)
Standard Hydraulic Flow
(mg/1) I/ Relationship
0.002 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
5.0 pCi/1 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Number of Maximum
Analyses Percent Value
Formation of Number of Exceeding Exceeding Obtained
Completion Analyses Standard Standard (mg/1) I/
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C 2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
C 1 Sandstone
Tres Hermanos-
C 2 Sandstone
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C 2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
C 1 Sandstone
Tres Hermanos-
C 2 Sandstone
1
2
1
1
6
9
2
8
3
1
4 4/
1 —
2 4/
8 7 5/ 87 410
10 10 5/ 100 240
1
10 2 5/ 20 22.0
4 1 5/ 25 5.6
4-7
-------
TABLE 1
Site Name: Ambrosia Lake (New Mexico)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 06/25/80 to 01/09/87
Page 5 of 6
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Selenium 0.01 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Silver 0.05 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Formation of Number of
Completion Analyses
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C 2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
C 1 Sandstone
Tres Hermanos-
C 2 Sandstone
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C 2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
C 1 Sandstone
Tres Hermanos-
C 2 Sandstone
8
4
2
2
18
12
3
12
7
1
2
1
1
7
10
2
8
3
Number of
Analyses
Exceeding
Standard
2
2
2
—
6
7
1
4
___
1
Percent
Exceeding
Standard
25
50
100
—
33
58
33
33
14
Maximum
Value
Obtained
(mg/1) I/
0.95
0.53
0.033
— -
0.147
0.019
0.127
0.225
0.15
4-8
-------
TABLE 1 Page 6 of 6
Site Name: Ambrosia Lake (New Mexico)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 06/25/80 to 01/09/87
Number of Maximum
Analyses Percent Value
Standard Hydraulic Flow Formation of Number of Exceeding Exceeding Obtained
Constituent (mg/1) I/ Relationship Completion Analyses Standard Standard (mg/1) I/
I/ Values are reported in mg/1 unless otherwise indicated.
2/ Uranium data available for 1 of 2 samples.
3/ Uranium not analyzed.
4/ Analyses for Ra-226 only.
5/ Ra-226 values. Ra-228 values were all less than the standard.
Standard not exceeded.
4-9
-------
TABLE 2 Page 1 of 8
Site Name: Ambrosia Lake (New Mexico)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 06/25/80 to 01/09/87
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Chloride 250 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Copper 1 . 0 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Formation of Number of
Completion Analyses
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
Cl Sandstone
Tres Hermanos-
C2 Sandstone
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
Cl Sandstone
Tres Hermanos-
C2 Sandstone
9
4
7
2
19
11
4
13
8
1
2
1
1
7
10
2
8
3
Number of Maximum
Analyses Percent Value
Exceeding Exceeding Obtained
Standard Standard (mg/1) I/
— _ _ — ---
—
4 21 489
___
2 50 300
2 15 270
___ ___
4-10
-------
TABLE 2 Page 2 of 8
Site Name: Ambrosia Lake (New Mexico)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 06/25/80 to 01/09/87
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Fluoride 1 . 4 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Hydrogen Sulfide 0.05 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Formation of Number of
Completion Analyses
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
Cl Sandstone
Tres Hermanos-
C2 Sandstone
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
Cl Sandstone
Tres Hermanos-
C2 Sandstone
7
4
1
2
12
11
3
12
7
1
1
1
1
1
1
1
1
1
Number of Maximum
Analyses Percent Value
Exceeding Exceeding Obtained
Standard Standard (mg/1) I/
___ ___ ___
3 75 2.2
__-. ___ __—
- —
2 16 15.0
10 90 21.0
1 33 2.2
6 50 2.1
___ ___ ___
___ ___ ___
___ — _ — -
4-11
-------
TABLE 2
Site Name: Ambrosia Lake (New Mexico)
Data Evaluation: Site Water Quality Compared to U.S.
plus Uranium and Molybdenum
Data Interval: 06/25/80 to 01/09/87
Page 3 of 8
EPA Standards Not Included in 40 CFR 192.32(a)
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Iron 0.30 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Manganese 0 . 05 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Formation of Number of
Completion Analyses
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
Cl Sandstone
Tres Hermanos-
C2 Sandstone
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
Cl Sandstone
Tres Hermanos-
C2 Sandstone
7
4
1
2
15
11
3
12
7
7
2
1
2
15
11
3
11
7
Number of
Analyses
Exceeding
Standard
1
4
3
2
3
6
1
14
_ —
2
6
6
Percent
Exceeding
Standard
14
26
27
66
42
85
50
93
___
66
54
85
Maximum
Value
Obtained
(mg/1) l/
0.61
5.49
1.46
4.13
28.8
0.17
0.07
0.68
___
4.23
0.13
1.82
4-12
-------
TABLE 2
Site Name: Ambrosia Lake (New Mexico)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included
plus Uranium and Molybdenum
Data Interval: 06/25/80 to 01/09/87
Page 4 of 8
in 40 CFR 192.32(a)
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Molybdenum 0.10 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Nitrate 2/ 44 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Formation of Number of
Completion Analyses
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
Cl Sandstone
Tres Hermanos-
C2 Sandstone
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
Cl Sandstone
Tres Hermanos-
C2 Sandstone
8
4
2
2
18
12
3
12
7
8
4
6
2
16
11
4
13
8
Number of
Analyses
Exceeding
Standard
7
3
2
2
18
12
3
12
6
2
1
1
5
2
7
Percent
Exceeding
Standard
88
75
100
100
100
100
100
100
86
25
25
6
45
50
53
Maximum
Value
Obtained
(mg/1) I/
0.22
1.87
0.50
0.17
225
250
3.17
10.3
0.35
49.0
55.0
— -
150
4900
140
400
4-13
-------
TABLE 2
Site Name: Ambrosia Lake (New Mexico)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included
plus Uranium and Molybdenum
Data Interval: 06/25/80 to 01/09/87
Page 5 of 8
in 40 CFR 192.32(a)
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
pH 3/ 6.5 to 8.5 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Sulfate 250 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Formation of Number of
Completion Analyses
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
Cl Sandstone
Tres Hermanos-
C2 Sandstone
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
Cl Sandstone
Tres Hermanos-
C2 Sandstone
9
4
7
2
18
11
4
13
8
9
4
7
2
19
12
4
13
8
Number of
Analyses
Exceeding
Standard
• ••
2
3
10
1
3
1
9
4
7
2
19
12
4
11
8
Percent
Exceeding
Standard
— — —
100
16
90
25
23
12
100
100
100
100
100
100
100
84
100
Maximum
Value
Obtained
(mg/1) I/
--—
12.2
9.97
10.13
11.18
12.46
11.92
4940
2750
2440
633
10,300
11,000
4440
4010
3970
4-14
-------
TABLE 2
Site Name: Ambrosia Lake (New Mexico)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included
plus Uranium and Molybdenum
Data Interval: 06/25/80 to 01/09/87
Page 6 of 8
in 40 CFR 192.32(a)
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Sulfide 0.05 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Total Solids 500 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Formation of Number of
Completion Analyses
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
Cl Sandstone
Tres Hermanos-
C2 Sandstone
Alluvium
Alluvium
Alluvium
Tres Hennanos-
C2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
Cl Sandstone
Tres Hermanos-
C2 Sandstone
1
1
1
1
6
9
2
7
3
8
4
2
2
17
10
3
12
7
Number of
Analyses
Exceeding
Standard
--—
1
1
6
9
2
7
3
8
4
2
2
17
10
3
12
7
Percent
Exceeding
Standard
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
Maximum
Value
Obtained
(mg/1) I/
— — —
0.
0.
0.
0.
0.
0.
0.
8080
4400
4060
1880
20,900
25,800
7250
7190
6490
10
10
10
10
10
10
10
4-15
-------
TABLE 2
Site Name: Ambrosia Lake (New Mexico)
Data Evaluation: .Site Water Quality Compared to U.S. EPA Standards Not Included
plus Uranium and Molybdenum
Data Interval: 06/25/80 to 01/09/87
Page 7 of 8
in 40 CFR 192.32(a)
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Uranium 4/ 0.044 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Zinc 5.0 Background
Upgradient
Cross-gradient
Cross-gradient
On-Site
On-Site
Down gradient
Down gradient
Down gradient
Formation of Number of
Completion Analyses
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hennanos-
Cl Sandstone
Tres Hermanos-
C2 Sandstone
Alluvium
Alluvium
Alluvium
Tres Hermanos-
C2 Sandstone
Alluvium
Uranium Mill
Tailings
Alluvium
Tres Hermanos-
Cl Sandstone
Tres Hermanos-
C2 Sandstone
8
3
2
2
17
10
3
11
7
1
1
1
1
6
9
2
7
3
Number of
Analyses
Exceeding
Standard
3
3
2
17
10
2
8
2
_.-•»
_——
___
Percent
Exceeding
Standard
37
100
100
100
100
66
72
29
r-
Maximum
Value
Obtained
(mg/1) I/
1.26
3.31
5.34
14.70
10.70
2.80
11.80
1.25
___
4-16
-------
TABLE 2 Page 8 of 8
Site Name: Ambrosia Lake (New Mexico)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 06/25/80 to 01/09/87
Number of Maximum
Analyses Percent Value
Standard Hydraulic Flow Formation of Number of Exceeding Exceeding obtained
Constituent (mg/1) I/ Relationship Completion Analyses Standard Standard (mg/1) I/
I/ Values are reported in mg/1 unless otherwise indicated.
2/ Concentrations of nitrate as nitrogen at a level of 10 mg/1 is equivalent to concentration of nitrate as nitrate at a
level of 44 mg/1. All analyses are reported in terms of nitrate as nitrate.
3/ pH reported in standard units.
4/ 30 pCi/1 of uranium is equivalent of 0.044 mg/1, assuming the bulk of uranium is U-238. All analyses are reported as
total uranium in mg/1.
Standard not exceeded.
4-17
-------
4.3 CANONSBURG, PENNSYLVANIA - SUMMARY OF WATER QUALITY
The collection of hydrogeological and groundwater quality
data for the Canonsburg site began in 1979. However, due to
the potential for high levels of radioactive contamination,
the location of wells was restricted. Also, aquifer pump
tests were prohibited due to the potential for withdrawing
radioactively contaminated groundwater. In 1982, additional
drilling was conducted to further characterize the ground-
water regime. The 1982 effort concluded that significant
data gaps still existed regarding the hydrogeological
information.
From December 1982 through March 1983, a third field effort
was undertaken to characterize the site hydrogeology.
During this effort, monitoring wells were constructed
on-site in the overburden and in the bedrock. Off-site
monitoring wells were constructed south of the site.
Aquifer data from the unconsolidated material and the
bedrock were collected. Surface water data from Chartiers
Creek were collected to determine the hydrological relation-
ship between the groundwater and Chartiers Creek.
The amount of groundwater quality data for the period 1979
to March 1983 is minimal. The value of these data may be
limited with regards to site groundwater quality character-
ization. This is primarily due to the early drilling
restrictions which applied to most of the site. The data
that are available for this period of time show that several
constituents in the groundwater beneath the site, and in the
vicinity of the site, exceeded existing standards. Some
on-site groundwater samples exceeded existing standards for
arsenic, chloride, iron, pH, selenium and sulfate. Nitrate,
pH and selenium exceeded the existing standards in some
off-site groundwater samples.
Remedial action at the process site is complete. The data
evaluated and presented in the following tables represent
post-closure groundwater quality data. These data are from
two quarterly post-remedial sampling efforts conducted
between 08/05/86 and 11/06/86. Presently, seven wells (four
on-site and three off-site) comprise the primary monitoring
network.
Two saturated zones are presently monitored. These are the
unconsolidated soils and shallow shale and limestone.
Recharge is from the east and discharge occurs to Chartiers
Creek to the north, west, and south. Some groundwater may
flow beneath Chartiers Creek in the shallow shale/limestone.
Approximately 12 wells have been identified within a one-
mile radius on the site. Most of these wells have been
abandoned , with the remaining wells receiving limited use,
primarily for watering gardens.
4-18
-------
Monitoring data from the site include upgradient, cross-
gradient and down gradient samples. Background data are not
available. Table 1 shows that none of the constituents
exceeded standards. However, this must be evaluated in
terms of the data time interval (six months) and that the
data are from post-closure monitoring.
Most of the groundwater from the contaminated alluvium
discharges to Chartier Creek within a few hundred feet of
the site; some may underflow the creek in shallow bedrock.
Modeling indicates that discharges of the mobile contami-
nants (NO3, Cl, SO4, TDS) will be within standards within 60
years and discharges of the attenuated contaminants (U, Mo,
metals) in excess of standards will continue for two to
three times as long.
4-19
-------
TABLE 1
Site Name: Canonsburg (Pennsylvania)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 08/05/86 to 11/06/86
Page 1 of 2
Constituent
Arsenic
Barium
Cadmium
Chromium
Gross Alpha
(excluding radon
and uranium)
Standard Hydraulic Flow
(mg/1) I/ Relationship
0.05 Upgradient
Cross-gradient
On-Site
1 . 0 Upgradient
Cross-gradient
On-Site
0.01 Upgradient
Cross-gradient
On-Site
0.05 Upgradient
Cross-gradient
On-Site
15.0 pCi/1 Upgradient
Cross-gradient
On-Site
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Number of
Analyses
5
2
8
5
2
8
5
2
8
5
2
8
1
1
1
Number of
Analyses
Exceeding
Standard
« •«
— --
Maximum
Percent Value
Exceeding Obtained
Standard (mg/1) I/
___ _ — _
— — — ...
"• — — — — —
4-20
-------
TABLE 1
Site Name: Canonsburg (Pennsylvania)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 08/05/86 to 11/06/86
Page 2 of 2
Constituent
Lead
Mercury
Ra-226 + Ra-228
(Radium)
Selenium
Silver
Standard Hydraulic Flow
(mg/1) I/ Relationship
0.05 Upgradient
Cross-gradient
On-Site
0.002 Upgradient
Cross-gradient
On-Site
5.0 pCi/1 Upgradient
Cross-gradient
On-Site
0.01 Upgradient
Cross-gradient
-------
TABLE 2 Page 1 of 4
Site Name: Canonsburg (Pennsylvania)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 08/05/86 to 11/06/86
Constituent
Chloride
Copper
Fluoride
Hydrogen Sulfide
Standard
(mg/1) I/
250
1.0
1.4
0.05
Hydraulic Flow
Relationship
Upgradient
Cross-gradient
On-Site
Upgradient
Cross-gradient
On-Site
Upgradient
Cross-gradient
On-Site
Upgradient
Cross-gradient
On-Site
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Number of
Analyses
5
2
8
5
2
8
5
2
8
1
1
1
Number of
Analyses
Exceeding
Standard
• »
E:
— — —
—
Percent
Exceeding
Standard
E
___
—
Maximum
Value
Obtained
(mg/1) I/
"•*"•"
"""•"•
— — —
— — -
4-22
-------
TABLE 2
Site Name: Canonsburg (Pennsylvania)
Data Evaluation: Site Water Quality Compared tc U.S. EPA Standards Not Included
plus Uranium and Molybdenum
Data Interval: 08/05/86 to 11/06/86
Page 2 of 4
in 40 CFR 192.32(a)
Constituent
Iron
Manganese
Molybdenum
Nitrate 2/
Standard
(mg/1) I/
0.30
0.05
0.10
44
Hydraulic Flow
Relationship
Upgradient
Cross-gradient
On-Site
Upgradient
Cross-gradient
On-Site
Upgradient
Cross-gradient
On-Site
Upgradient
Cross-gradient
On-Site
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Number of
Analyses
5
2
8
5
2
8
5
2
8
5
2
8
Number of
Analyses
Exceeding
Standard
4
2
2
5
2
8
5
2
8
Percent
Exceeding
Standard
80
100
25
100
100
100
100
100
100
Maximum
Value
Obtained
(mg/1) I/
14.5
1.42
14.7
3.32
11.5
9.41
0.27
0.18
0.20
4-23
-------
TABLE 2 Page 3 of 4
Site Name: Canonsburg (Pennsylvania)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 08/05/86 to 11/06/86
Constituent
PH 3/
Sulfate
Sulfide
Total Solids
Standard Hydraulic Flow
(mg/1) I/ Relationship
6.5 to 8.5 Upgradient
Cross-gradient
On-Site
250 Upgradient
Cross-gradient
On-Site
0.05 Upgradient
Cross-gradient
On-Site
500 Upgradient
Cross-gradient
On-Site
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Number of
Analyses
5
2
8
5
2
8
4
2
8
5
2
8
Number of
Analyses
Exceeding
Standard
3
6
8
4
2
8
2
8
Percent
Exceeding
Standard
60
75
100
100
100
100
40
100
Maximum
Value
Obtained
(mg/1) I/
5.60
— — -
6.34
626
0.10
0.10
0.10
802
1310
4-24
-------
TABLE 2
Site Name: Canonsburg (Pennsylvania)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included
plus Uranium and Molybdenum
Data Interval: 08/05/86 to 11/06/86
Page 4 of 4
in 40 CFR 192.32(a)
Constituent
Uranium 4/
Zinc
Standard
(mg/1) I/
0.044
5.0
Hydraulic Flow
Relationship
Upgradient
Cross-gradient
On-Site
Upgradient
Cross-gradient
On-Site
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Number of
Analyses
5
2
8
5
2
8
Number of
Analyses
Exceeding
Standard
2
2
Percent
Exceeding
Standard
100
25
Maximum
Value
Obtained
(mg/1) I/
0.0221
0.0492
I/ Values are reported in mg/1 unless otherwise indicated.
2/ Concentrations of nitrate as nitrogen at a level of 10 mg/1 is equivalent to concentration of nitrate as nitrate at a
level of 44 mg/1. All analyses are reported in terms of nitrate as nitrate.
3_/ pH reported in standard units.
4/ 30 pCi/1 of uranium is equivalent of 0.044 mg/1, assuming the bulk of uranium is U-238. All analyses are reported as
total uranium in mg/1.
Standard not exceeded.
4-25
-------
4.4 DURANGO, COLORADO - SUMMARY OF WATER QUALITY
The analysis of groundwater quality at the Durango site
involved upgradient and down gradient data. No background
or preprocessing era data were available. There are no
current groundwater users within two miles down gradient of
the site.
Levels of arsenic, chromium and selenium exceeded the
standards in some samples. Selenium exceeded the standard
in one upgradient sample by a factor of 35 and in nearly 80
percent of the down gradient samples by factors as high as
190. Arsenic and chromium exceeded the standards only in
the down gradient samples, arsenic by a factor of 16 and
chromium by a factor of two.
The contaminated groundwater discharges to the Animas River
within 100 to 500 feet of the piles and ponds. Modeling
indicates that the mobile contaminants will be flushed from
the alluvial aquifer in approximately 5 years and from the
Menefee Formation in 40 years. Flushing of the attenuated
contaminants from the alluvial aquifer will take 15 years
and from the Menefee Formation about 40 years.
4-26
-------
TABLE 1
Site Name: Durango (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 09/01/82 to 11/13/85
Page 1 of 5
Constituent
Arsenic
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
0.05
Barium
1.0
Upgradient
Down gradient
Down gradient
Down gradient
Upgradient
Down gradient
Down gradient
Down gradient
Gravel or sandy
gravel, poorly
graded
Gravel or sandy
gravel, poorly
graded
Silty Sand or
Silty gravelly
sand
Shale
Gravel or sandy
gravel, poorly
graded
Gravel or sandy
gravel, poorly
graded
Silty Sand or
Silty gravelly
sand
Shale
21
22
28
16
0.83
0.10
4-27
-------
TABLE 1
Site Name: Durango (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 09/01/82 to 11/13/85
Page 2 of 5
Constituent
Cadmium
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
Chromium
0.01 Upgradi ent
Down gradient
Down gradient
Down gradient
0.05 Upgradient
Down gradient
Down gradient
Down gradient
Gravel or sandy
gravel, poorly
graded
Gravel or sandy
gravel, poorly
graded
Silty Sand or
Silty gravelly
sand
Shale
Gravel or sandy
gravel, poorly
graded
Gravel or sandy
gravel, poorly
graded
Silty sand or
Silty gravelly
sand
Shale
21
16
0.10
20
4-28
-------
TABLE 1
Site Name: Durango (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 09/01/82 to 11/13/85
Page 3 of 5
Constituent
Standard Hydraulic Flow
(mg/1) I/ Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
Gross Alpha
(excluding radon
and uranium)
Lead
15.0 pci/l Upgradient
Down gradient
Down gradient
Down gradient
0.05 Upgrad ient
Down gradient
Down gradient
Down gradient
Gravel or sandy
gravel, poorly
graded
Gravel or sandy
gravel, poorly
graded
Silty Sand or
Silty gravelly
sand
Shale
Gravel or sandy
gravel, poorly
graded
Gravel or sandy
gravel, poorly
graded
Silty Sand or
Silty gravelly
sand
Shale
21
20
4-29
-------
TABLE 1
Site Name: Durango (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 09/01/82 to 11/13/85
Page 4 of 5
Constituent
Mercury
Ra-226 + Ra-228
(Radium)
Standard Hydraulic Flow
(mg/1) I/ Relationship
0.002 Upgradient
Down gradient
Down gradient
Down gradient
5.0 pCi/1 Upgradient
Down gradient
Down gradient
Down gradient
Number of Maximum
Analyses Percent Value
Formation of Number of Exceeding Exceeding Obtained
Completion Analyses Standard Standard (mg/1) I/
Gravel or sandy 1
gravel, poorly
graded
Gravel or sandy 1
gravel , poorly
graded
Silty Sand or 1
Silty gravelly
sand
Shale 1
Gravel or sandy 2 2/ - — ~-~
gravel, poorly
graded
Gravel or sandy 12 2/
gravel, poorly
graded
Silty Sand or 2 2/
Silty gravelly
sand
Shale 10 2/
4-30
-------
TABLE 1
Site Name: Durango (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 09/01/82 to 11/13/85
Page 5 of 5
Constituent
Selenium
Silver
Standard Hydraulic Flow
(mg/1) I/ Relationship
0.01 Upgradient
Down gradient
Down gradient
Down gradient
0.05 Upgradient
Formation of Number of
Completion Analyses
Gravel or sandy
gravel, poorly
graded
Gravel or sandy
gravel , poorly
graded
Silty Sand or
Silty gravelly
sand
Shale
Gravel or sandy
5
21
6
22
1
Number of
Analyses
Exceeding
Standard
1
17
4
18
Percent
Exceeding
Standard
20
80
66
81
Maximum
Value
Obtained
(mg/1) I/
0.36
1.20
1.90
1.60
Down gradient
Down gradient
Down gradient
gravel, poorly
graded
Gravel or sandy
gravel, poorly
graded
Silty Sand or
Silty gravelly
sand
Shale
I/ Values are reported in mg/1 unless otherwise indicated.
2/ Analyses for Ra-226 only.
Standard not exceeded.
4-31
-------
TABLE 2
Site Name: Durango (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 09/01/82 to 11/13/85
Page 1 of 8
Constituent
Chloride
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
250
Copper
1.0
Upgradient
Down gradient
Down gradient:
Down gradient
Upgradient
Down gradient
Down gradient.
Down gradient
Gravel or sandy 5
gravel, poorly
graded
Gravel or sandy 21
gravel, poorly
graded
Silty sand or 6
silty gravelly
sand
Shale 22
Gravel or sandy 4
gravel, poorly
graded
Gravel or sandy 21
gravel, poorly
graded
Silty sand or 6
silty gravelly
sand
Shale 20
12
42
66
54
1100
390
1100
4-32
-------
TABLE 2
Site Name: Durango (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 09/01/82 to 11/13/85
Page 2 of 8
Constituent
Fluoride
Standard
(mg/1) I/
1.4
Hydraulic Flow
Relationship
Upgradient
Formation of
Completion
Gravel or sane
Number of
Analyses
iy 1
Number of
Analyses
Exceeding
Standard
___
Percent
Exceeding
Standard
_ __
Maximum
Value
Obtained
(mg/1) I/
___
Hydrogen Sulfide
Down gradient
Down gradient
Down gradient
0.05 Upgrad i ent
Down gradient
Down gradient
Down gradient
gravel, poorly
graded
Gravel or sandy
gravel, poorly
graded
Silty sand or
silty gravelly
sand
Shale
Gravel or sandy
gravel, poorly
graded
Gravel or sandy
gravel, poorly
graded
Silty sand or
silty gravelly
sand
Shale
4-33
-------
TABLE 2
Site Name: Durango (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 09/01/82 to 11/13/85
Page 3 of 8
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Iron 0.3 Upgradient
Down gradient
Down gradient
Down gradient
Manganese 0.05 Upgradient
Down gradient
Down gradient
Down gradient
Formation of Number of
Completion Analyses
Gravel or sandy 5
gravel , poorly
graded
Gravel or sandy 21
gravel, poorly
graded
Silty sand or 6
silty gravelly
sand
Shale 22
Gravel or sandy 1
gravel , poorly
graded
Gravel or sandy 1
gravel , poorly
graded
Silty sand or 1
silty gravelly
sand
Shale 1
Number of Maximum
Analyses Percent Value
Exceeding Exceeding Obtained
Standard Standard (mg/1) I/
1 20 0.63
1 4 1.00
3 50 16.30
1 4 0.32
— — — — — —
4-34
-------
TABLE 2
Site Name: Durango (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 09/01/82 to 11/13/85
Page 4 of 8
Constituent
Molybdenum
Nitrate 2/
Standard Hydraulic Flow
(mg/1) I/ Relationship
0 . 10 Upgradient
Down gradient
Down gradient
Down gradient
44 Upgradient
Formation of Number of
Completion Analyses
Gravel or sandy
gravel, poorly
graded
Gravel or sandy
gravel , poorly
graded
Silty sand or
silty gravelly
sand
Shale
Gravel of sandy
5
21
6
22
5
Number of
Analyses
Exceeding
Standard
1
8
3
6
Percent
Exceeding
Standard
20
38
50
27
Maximum
Value
Obtained
(mg/1) I/
0.17
0.25
0.14
0.30
Down gradient
Down gradient
Down gradient
gravel, poorly
graded
Gravel or sandy
gravel, poorly
graded
Silty sand or
silty gravelly
sand
Shale
21
61.0
4-35
-------
TABLE 2
Site Name: Durango (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 09/01/82 to 11/13/85
Page 5 of 8
Constituent
PH 3/
Sulfate
Standard Hydraulic Flow
(mg/1) I/ Relationship
6.5 to 8.5 Upgradient
Down gradient
Down gradient
Down gradient
250 Upgradient
Formation of Number of
Completion Analyses
Gravel or sandy 5
gravel , poorly
graded
Gravel or sandy 20
gravel, poorly
graded
Silty sand or 4
silty gravelly
sand
Shale 22
Gravel or sandy 5
Number of
Analyses
Exceeding
Standard
2
2
Percent
Exceeding
Standard
9
40
Maximum
Value
Obtained
(mg/1) I/
6.4/8.9
940
Down gradient
Down gradient
Down gradient
gravel, poorly
graded
Gravel or sandy 21
gravel, poorly
graded
Silty sand or 5
silty gravelly
sand
Shale 22
20
22
95
100
100
6006
3100
3664
4-36
-------
TABLE 2
Site Name: Durango (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 09/01/82 to 11/13/85
Page 6 of 8
Constituent
Sulfide
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
0.05
Total Solids
500
Upgradient
Down gradient
Down gradient
Down gradient
Upgradient
Down gradient
Down gradient
Down gradient
Gravel or sandy
gravel, poorly
graded
Gravel or sandy
gravel, poorly
graded
Silty sand or
silty gravelly
sand
Shale
Gravel or sandy
gravel, poorly
graded
Gravel or sandy
gravel, poorly
graded
Silty sand or
silty gravelly
sand
Shale
100
744
100
5820
4-37
-------
TABLE 2
Site Name: Durango (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 09/01/82 to 11/13/85
Page 7 of 8
Constituent
Uranium 4/
Zinc
Standard Hydraulic Flow
(mg/1) I/ Relationship
0.044 Upgradient
Down gradient
Down gradient
Down gradient
5 . 0 Upgradient
Formation of Number of
Completion Analyses
Gravel or sandy 5
gravel , poorly
graded
Gravel or sandy 21
gravel , poorly
graded
Silty sand or 6
silty gravelly
sand
Shale 22
Gravel of sandy 4
Number of
Analyses
Exceeding
Standard
1
18
6
22
Percent
Exceeding
Standard
20
86
100
100
Maximum
Value
Obtained
(mg/1) I/
0.15
6.20
2.40
4.07
— _
Down gradient
Down gradient
Down gradient
gravel, poorly
graded
Gravel or sandy 21
gravel, poorly
graded
Silty sand or 6
silty gravelly
sand
Shale 20
4-38
-------
TABLE 2 Page 8 of 8
Site Name: Durango (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 09/01/82 to 11/13/85
Number of Maximum
Analyses Percent Value
Standard Hydraulic Flow Formation of Number of Exceeding Exceeding Obtained
Constituent (mg/1) I/ Relationship Completion Analyses Standard Standard (mg/1) I/
I/ Values are reported in mg/1 unless otherwise indicated.
2/ Concentrations of nitrate as nitrogen at a level of 10 mg/1 is equivalent to concentration of nitrate as nitrate at a
level of 44 mg/1. All analyses are reported in terms of nitrate as nitrate.
3/ pH reported in standard units.
4/ 30 pCi/1 of uranium is equivalent of 0.044 mg/1, assuming the bulk of uranium is U-238. All analyses are reported as
total uranium in mg/1.
Standard not exceeded.
4-39
-------
4.5 GRAND JUNCTION, COLORADO - SUMMARY OF WATER QUALITY
The Grand Junction process site lies in an industrial area
along the northern bank of the Colorado River. Sedimentary
units in and around the site are, in ascending order, the
Dakota Sandstone, the Mancos Shale, and alluvium. Two
drillings programs were conducted; the first phase was to
determine the source of contamination to the alluvium; the
second considered background and down gradient hydraulics
and water quality in the alluvium and underlying beds of the
Mancos Shale and Dakota Sandstone.
Groundwater sampling indicated that limits of concentrations
for arsenic, cadmium, radium, chromium, selenium, and gross
alpha were exceeded. Arsenic and cadmium concentrations
were higher in on-site (alluvium and tailings) samples than
in other localities sampled in the alluvium. One of 23
upgradient analyses for chromium and twelve out of 33
on-site analysis for selenium exceeded the limit for the
standard. Four of 9 down gradient samples exceeded the
standard for gross alpha. Eight of 18 on-site analyses for
radium as well as three of 30 down gradient radium samples,
exceeded the limit for the standard.
Groundwater flow discharges in the Colorado River with some
possibly contributing to recharge of the Dakota Sandstone at
a subcrop 1/2 mile west of the site. Based on modeling
results, discharge and dispersal of the mobile contaminants
is expected within 50 to 60 years; uranium and ammonia may
persist in the alluvial aquifers for 150 to 300 years.
4-40
-------
TABLE 1
Site Name: Grand Junction (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 09/23/77 to 09/11/85
Page 1 of 4
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Arsenic 0 . 05 Background
Upgradient
Cross-gradient
On-Site
On-Site
Down gradient
Barium 1 . 0 Background
Upgradient
Cross-gradient
On-Site
On-Site
Down gradient
Cadmium 0.01 Background
Upgradient
Cross-gradient
On-Site
On-Site
Down gradient
Formation of 1
Completion ;
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
lumber of
Analyses
6
23
9
32
1
39
6
23
9
30
1
39
6
22
9
24
1
31
Number of Maximum
Analyses Percent Value
Exceeding Exceeding Obtained
Standard Standard (mg/1) I/
5 15 0.18
1 100 1.68
1 2 0.11
6 25 0.42
1 100 0.035
___ —__ — — —
4-41
-------
TABLE 1
Site Name: Grand Junction (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 09/23/77 to 09/11/85
Page 2 of 4
Constituent
Chromium
Gross Alpha
(excluding radon
and uranium)
Standard Hydraulic Flow
(mg/1) I/ Relationship
0 . 05 Background
Upgradient
Cross-gradient
On-Site
On-Site
Down gradient
15.0 pCi/1 Background
Upgradient
Cross-gradient
On-Site
On-Site
Down gradient
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
Number of
Analyses
6
23
9
31
1
39
2 2/
4 2/
3 2/
4 3/
1
9 4/
Number of
Analyses Percent
Exceeding Exceeding
Standard Standard
— — •• •»_—
1 4
_ —
___ ___
___ ___
--— — —
2/ 2/
2/ 2/
2/ 2/
3 100
4 100
Maximum
Value
Obtained
(mg/1) I/
___
0.07
___
___
___
---
2/
2/
129.20
187.40
Lead
0.05 Background
Upgradient
Cross-gradient
On-Site
On-Site
Down gradient
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
4
13
6
16
1
22
4-42
-------
TABLE 1
Site Name: Grand Junction (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 09/23/77 to 09/11/85
Page 3 of 4
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Mercury 0.002 Background
Upgradient
Cross-gradient
On-Site
On-Site
Down gradient
Ra-226 + Ra-228 5.0 pCi/1 Background
(Radium) Upgradient
Cross-gradient
On-Site
On-Site
Down gradient
Selenium 0.01 Background
Upgradient
Cross-gradient
On-Site
On-Site
Down gradient
Formation of 1
Completion I
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
lumber of
Unalyses
6
22
9
24
1
31
5
18
7
18 5/
1
30 5/
6
23
9
32
1
39
Number of
Analyses
Exceeding
Standard
8 6/
3 6/
1
11
1
1
Percent
Exceeding
Standard
___
44
10
16
— — —
34
100
2
Maximum
Value
Obtained
(mg/1) I/
— —
29.0
18.0
0.014
___
0.24
1.69
0.012
4-43
-------
TABLE 1
Site Name: Grand Junction (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 09/23/77 to 09/11/85
Page 4 of 4
Constituent
Silver
Standard Hydraulic Flow
(mg/1) I/ Relationship
0.05 Background
Upgradient
Cross-gradient
On-Site
On-Site
Down gradient
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
Number of
Analyses
4
13
6
16
1
22
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
I/ Values are reported in mg/1 unless otherwise indicated.
2/ Uranium not analyzed.
3/ Uranium not analyzed for one sample.
4/ Uranium analyzed in 4 of 9 samples.
5/ Ra-226 only.
6/ Values for Ra-226 only. Ra-228 values were all less than the standard.
Standard not exceeded.
4-44
-------
TABLE 2
Site Name: Grand Junction (Colorado)
Data Evaluation: Site Water Quality Compared to U.S.
plus Uranium and Molybdenum
Data Interval: 09/23/77 to 09/11/85
Page 1 of 5
EPA Standards Not Included in 40 CFR 192.32(a)
Constituent
Chloride
Copper
Fluoride
Standard Hydraulic Flow
(mg/1) I/ Relationship
250 Background
Upgradient
Cross-gradient
On-Site
On-Site
Down gradient
1 . 0 Background
Upgradient
Cross-gradient
On-site
On-Site
Down gradient
1 . 4 Background
Upgradient
Cross-gradient
On-Site
On-Site
Down gradient
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
Number of
Analyses
52
23
9
32
1
40
6
23
9
32
1
39
6
22
9
24
1
31
Number of
Analyses
Exceeding
Standard
39
15
9
32
1
40
___
— — —
___
2
20
1
8
Percent
Exceeding
Standard
75
65
100
100
100
100
— -
— — —
___
9
83
100
25
Maximum
Value
Obtained
(mg/1) I/
473
783
1250
1030
2990
1270
___
___
1.60
4.90
16.0
3.70
4-45
-------
TABLE 2
Site Name: Grand Junction (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included
plus Uranium and Molybdenum
Data Interval: 09/23/77 to 09/11/85
in 40 CFR 192.32(a)
Page 2 of 5
Standard
Constituent (mg/1) I/
Hydrogen Sulfide 0.05
Iron 0.30
Manganese 0 . 05
Hydraulic Flow
Relationship
Background
Upgradient
Cross-gradient
On-Site
On-Site
Down gradient
Background
Upgradient
Cross-gradient
On-Site
On-Site
Down gradient
Background
Upgradient
Cross-gradient
on-site
On-site
Down gradient
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
Number of
Analyses
4
13
6
12
1
18
6
23
9
32
1
39
6
23
9
32
1
39
Number of
Analyses
Exceeding
Standard
4
13
6
12
18
4
10
8
22
26
6
23
9
32
1
39
Percent
Exceeding
Standard
100
100
100
100
100
66
43
88
68
66
100
100
100
10
100
100
Maximum
Value
Obtained
(mg/1) I/
1.20
0.20
0.36
0.20
0.20
1.20
3.04
5.70
12.00
16.00
8.74
2.91
4.60
10.00
0.33
334
4-46
-------
TABLE 2
Site Name: Grand Junction (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included
plus Uranium and Molybdenum
Data Interval: 09/23/77 to 09/11/85
Page 3 of 5
in 40 CFR 192.32(a)
Constituent
Molybdenum
Nitrate 2/
PH 3/
Standard Hydraulic Flow
(mg/1) I/ Relationship
0.10 Background
Upgradient
Cross-gradient
On-Site
On-site
Down gradient
44 Background
Upgradient
Cross-gradient
On-Site
On-Site
Down gradient
6.5 to 8.5 Background
Upgradient
Cross-gradient
On-Site
On-Site
Down gradient
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
Number of
Analyses
6
23
9
32
1
39
8
23
9
28
1
35
52
23
9
32
1
39
Number of
Analyses
Exceeding
Standard
__—
6
5
24
1
17
1
1
— — —
Percent
Exceeding
Standard
26
56
75
100
44
___
___
3
100
— •• —
- —
— —
—
Maximum
Value
Obtained
(mg/1) I/
0.15
0.14
0.53
8.65
0.47
— — —
— — —
50.0
1100
BMW
— — —
— — —
— — -
4-47
-------
TABLE 2
Site Name: Grand Junction (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included
plus Uranium and Molybdenum
Data Interval: 09/23/77 to 09/11/85
in 40 CFR 192.32(a)
Page 4 of 5
Constituent
Sulfate
Sulfide
Total Solids
Standard Hydraulic Flow
(mg/1) I/ Relationship
250 Background
Upgradient
Cross-gradient
On-Site
On-Site
Down gradient
0.05 Background
Upgradient
Cross-gradient
On-Site
On-Site
Down gradient
500 Background
Upgradient
Cross-gradient
On-Site
On-Site
Down gradient
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
Number of
Analyses
52
23
9
32
1
39
2
9
3
8
1
52
23
9
32
1
39
Number of
Analyses
Exceeding
Standard
52
20
9
32
1
39
2
9
3
8
52
22
9
32
___
39
Percent
Exceeding
Standard
100
86
100
100
100
100
100
100
100
100
100
95
100
100
___
100
Maximum
Value
Obtained
(mg/l) I/
4170
3410
4000
4900
6110
4500
0.10
0.10
0.10
0.10
7220
6930
8530
8100
___
12,134
4-48
-------
TABLE 2
Site Name: Grand Junction (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included
plus Uranium and Molybdenum
Data Interval: 09/23/77 to 09/11/85
Page 5 of 5
in 40 CFR 192.32(a)
Constituent
Uranium 4/
Zinc
Standard Hydraulic Flow
(mg/1) I/ Relationship
0.044 Background
Upgradient
Cross-gradient
On-Site
On-Site
Down gradient
5 . 0 Background
Upgradient
Cross-gradient
On-Site
On-Site
Down gradient
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Uranium Mill
Tailings
Alluvium
Number of
Analyses
1
1
1
3
1
4
6
23
9
32
1
39
Number of
Analyses
Exceeding
Standard
___
3
___
4
Percent
Exceeding
Standard
_ —
100
100
Maximum
Value
Obtained
(mg/1) I/
0.185
0.445
I/ Values are reported in mg/1 unless otherwise indicated.
2/ Concentrations of nitrate as nitrogen at a level of 10 mg/1 is equivalent to concentration of nitrate as nitrate at a
level of 44 mg/1. All analyses are reported in terms of nitrate as nitrate.
3/ pH reported in Standard units.
4/ 30 pci/l of uranium is equivalent of 0.044 mg/1, assuming the bulk of uranium is U-238. All analyses are reported as
total uranium in mg/1.
Standard not exceeded.
4-49
-------
4.6 GUNNISON, COLORADO - SUMMARY OF WATER QUALITY
The site is immediately south of the City of Gunnison,
Colorado; and is between the Gunnison River and Tomichi
Creek. The site overlies the principal aquifer of the area.
More than 75 wells, most of them domestic wells less than 30
feet deep, are within one mile of the site. The City of
Gunnison operates a municipal well field approximately one
mile north (upgradient) of the site.
The quality of background water is generally potable with
some exceptions. High concentrations of iron are found in
the alluvial aquifer. Hydrogen sulfide is found in a
reducing zone along the Gunnison River.
The groundwater analyses for the Gunnison site included
background, upgradient, cross-gradient, on-site and down
gradient data. All data are from wells in the alluvium.
Barium was the only constituent which exceeded the stan-
dards in the background samples. One of 21 background
samples exceeded the barium standard. No constituents
exceeded the standards in the upgradient or cross-gradient
wells.
Arsenic and gross alpha exceeded the standards in the
on-site samples. The arsenic standard was exceeded in 3 out
of 7 samples, with a maximum value exceeding the standard by
a factor of more than four. One gross alpha sample was
analyzed and it exceeded the standard by a factor of more
than ten.
The down gradient samples contained the greatest number of
contaminants. In these samples the standards were exceeded
for arsenic, cadmium, gross alpha, mercury and selenium.
Two out of 123 samples exceeded the arsenic standard by a
factor of less than two. The maximum values for both
cadmium and gross alpha exceeded standards by more than a
factor of three. The one mercury sample analyzed exceeded
the standard by a factor of 14,300. Nine out of 123 samples
analyzed for selenium exceeded the standard. The maximum
value for selenium was more than a factor of 10 greater than
the standard.
The contaminants disperse in the alluvial aquifer which
discharges at the confluence of the Gunnison River and
Tomichi Creek, 2 miles from the site. Modeling indicates
that discharges of the mobile contaminants will reach
background standards in approximately 75 years. The dis-
charge period of the attenuated contaminants was not
modeled.
4-50
-------
TABLE 1
Site Name: Gunnison (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 10/12/83 to 06/20/85
Page 1 of 3
Constituent
Arsenic
Barium
Cadmium
Chromium
Standard Hydraulic Flow
(mg/1) I/ Relationship
0.05 Background
Upgradient
Cross-gradient
On-Site
Down gradient
1 . 0 Background
Upgradient
Cross-gradient
On-Site
Down gradient
0.01 Background
Upgradient
Cross-gradient
On-Site
Down gradient
0.05 Background
Upgradient
Cross-gradient
On-Site
Down gradient
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Number of
Analyses
21
5
2
7
123
21
5
2
7
123
21
5
2
7
123
21
5
2
7
122
Number of
Analyses
Exceeding
Standard
— —
-— —
3
2
1
— — —
— --
— — —
- —
7
--—
-—
Percent
Exceeding
Standard
— — —
— — —
42
2
5
— —
— --
— — ••
— — —
6
— — —
— --
Maximum
Value
Obtained
(mg/1) I/
— — —
— — —
0.23
0.07
1.2
___
___
— — —
— — —
— — —
— — -
— — -
0.034
— — —
— — —
4-51
-------
TABLE 1
Site Name: Gunnison (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 10/12/83 to 06/20/85
Page 2 of 3
Constituent
Gross Alpha
(excluding radon
and uranium)
Lead
Mercury
Ra-226 + Ra-228
(Radium)
Standard Hydraulic Flow
(mg/1) I/ Relationship
15.0 pCi/1 Background
Upgradient
Cross-gradient
On-Site
Down gradient
0.05 Background
Upgradient
Cross-gradient
On-Site
Down gradient
0.002 Background
Upgradient
Cross-gradient
On-Site
Down gradient
5.0 pCi/1 Background
Upgradient
Cross-gradient
On-Site
Down gradient
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Number of
Analyses
5
1
1
1
11
21
5
2
7
121
1
1
1
1
1
6 2/
2
1
4 2/
23
Number of
Analyses
Exceeding
Standard
___
1
4
___
1
___
Percent
Exceeding
Standard
100
36
100
Maximum
Value
Obtained
(mg/1) I/
151.12
49.98
___
-— —
28.6
4-52
-------
TABLE 1
Site Name: Gunnison (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 10/12/83 to 06/20/85
Page 3 of 3
Constituent
Selenium
Silver
Standard
(mg/1) I/
0.01
0.05
Hydraulic Flow
Relationship
Background
Upgradient
Cross-gradient
On-Site
Down gradient
Background
Upgradient
Cross-gradient
On-Site
Down gradient
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Number of
Analyses
21
5
2
7
123
1
1
1
1
1
Number of
Analyses
Exceeding
Standard
9
— — —
Percent
Exceeding
Standard
7
— — —
Maximum
Value
Obtained
(mg/1) I/
0.103
_._
I/ Values are reported in mg/1 unless otherwise indicated.
2/ Analyses for Ra-226 only.
— Standard not exceeded.
4-53
-------
TABLE 2
Site Name: Gunnison (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included
plus Uranium and Molybdenum
Data Interval: 10/12/83 to 06/20/85
Page 1 of 4
in 40 CFR 192.32(a)
Standard
Constituent (mg/1) I/
Chloride 250
Copper 1 . 0
Fluoride 1.4
Hydrogen Sulfide 0.05
Iron 0.30
Hydraulic Flow
Relationship
Background
Upgradient
Cross-gradient
On-Site
Down gradient
Background
Upgradient
Cross-gradient
On-Site
Down gradient
Background
Upgradient
Cross-gradient
On-Site
Down gradient:
Background
Upgradient
Cross-gradient
On-Site
Down gradient
Background
Upgradient
Cross-gradient
On-Site
Down gradient
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Number of
Analyses
21
5
2
7
123
15
3
1
5
81
15
2
1
4
64
1
1
1
1
1
21
5
2
7
122
Number of
Analyses
Exceeding
Standard
4
10
2
7
69
Percent
Exceeding
Standard
6
47
100
100
56
Maximum
Value
Obtained
(mg/1) I/
2.60
5.63
1.90
37.80
101
4-54
-------
TABLE 2
Site Name: Gunnison (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included
plus Uranium and Molybdenum
Data Interval: 10/12/83 to 06/20/85
Page 2 of 4
in 40 CFR 192.32(a)
Constituent
Manganese
Molybdenum
Nitrate 2/
PH 3/
Sulfate
Standard Hydraulic Flow
(mg/1) I/ Relationship
0.05 Background
Upgradient
Cross-gradient
On-Site
Down gradient
0.10 Background
Upgradient
Cross-gradient
On-Site
Down gradient
4 4 Background
Upgradient
Cross-gradient
On-Site
Down gradient
6.5 to 8.5 Background
Upgradient
Cross-gradient
On-Site
Down gradient
250 Background
Upgradient
Cross-gradient
On-Site
Down gradient
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Number of
Analyses
15
5
2
6
101
21
5
2
7
123
21
5
2
7
123
21
5
2
7
117
21
5
2
7
122
Number of
Analyses
Exceeding
Standard
11
2
2
6
85
2
— — —
6
1
7
66
___
7
62
Percent
Exceeding
Standard
73
40
100
100
84
— -—
29
— — —
- —
4
50
100
56
___
100
50
Maximum
Value
Obtained
(mg/1) I/
4.69
0.29
2.09
34.30
77.00
-— —
— —
0.18
— — —
--—
— — —
110
6.08
5.66
5.08/12.32
___
1480
1820
4-55
-------
TABLE 2
Site Name: Gunnison (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included
plus Uranium and Molybdenum
Data Interval: 10/12/83 to 06/20/85
Page 3 of 4
in 40 CFR 192.32(a)
Constituent
Sulfide
Total Solids
Uranium 4/
Zinc
Standard Hydraulic Flow
(mg/1) I/ Relationship
0.05 Background
Upgradient
Cross-gradient
On-Site
Down gradient
500 Background
Upgradient
Cross-gradient
On-Site
Down gradient
0.044 Background
Upgradient
Cross-gradient
On-Site
Down gradient
5 . 0 Background
Upgradient
Cross-gradient
On-Site
Down gradient
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Number of
Analyses
6
2
1
2
43
21
5
2
7
122
15
2
1
5
78
15
3
1
5
82
Number of
Analyses
Exceeding
Standard
6
2
1
2
43
1
7
78
2
29
Percent
Exceeding
Standard
100
100
100
100
100
4
- —
100
63
— — -
— —
40
37
— —
___
Maximum
Value
Obtained
(mg/1) I/
0.10
0.10
0.10
0.10
1.00
713
— — —
— — —
2510
3160
— — —
___
0.1160
1.20
—
—
— — —
— -
4-56
-------
TABLE 2 Page 4 of 4
Sita Name: Gunnison (Colorado)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 10/12/83 to 06/20/85
Number of Maximum
Analyses Percent Value
Standard Hydraulic Flow Formation of Number of Exceeding Exceeding Obtained
Constituent (mg/1) I/ Relationship Completion Analyses Standard Standard (mg/1) I/
I/ Values are reported in mg/1 unless otherwise indicated.
2/ Concentrations of nitrate as nitrogen at a level of 10 mg/1 is equivalent to concentration of nitrate as nitrate at a
level of 44 mg/1. All analyses are reported in terms of nitrate as nitrate.
3/ pH reported in standard units.
4/ 30 pCi/1 of uranium is equivalent of 0.044 mg/1, assuming the bulk of uranium is U-238. All analyses are reported as
total uranium in mg/1.
Standard not exceeded.
4-57
-------
4.7 LAKEVIEW, OREGON - SUMMARY OF WATER QUALITY
Groundwater at the Lakeview site is relatively shallow (from
5 feet to 120 feet below land surface). The aquifers of
concern are unconsolidated lacustrine and alluvial materi-
als. The unconsolidated sediments are thick sequences of
clay, silt, and sand which extend to probably 5000 feet in
depth at the process site.
Preprocessing era data are not available for the Lakeview
site. The non-geothermal background groundwater is potable,
except that the manganese standard is exceeded in some
instances. The geothermal background water exceeds the
standards for arsenic, fluoride and total dissolved solids.
Domestic, irrigation and municipal wells are in use in the
vicinity of the site. An inventory of wells in the site
vicinity indicates that most of these wells are at depth of
100 feet or greater.
Constituents which exceeded the standards at the Lakeview
site are arsenic, cadmium, chromium, gross alpha, radium and
selenium. Arsenic exceeded the standard in background,
on-site and down gradient samples. Cadmium exceeded the
standard in both on-site and down gradient samples. Down
gradient samples contained the largest number of contam-
inants, as arsenic, cadmium, chromium, gross alpha and
radium exceeded the standards in some of the samples.
Cadmium values were greater in the down gradient samples
than in the on-site samples. Three down gradient samples
exceeded the standard, with the maximum value 31 times the
standard. Only one on-site sample exceeded the standard,
with the maximum value 4 times the standard.
The contaminant in the upper, unconsolidated sedimentary
unit will disperse. No discharge point has been identified,
and the plume was not modeled. However, because of a strong
upward flow gradient from leaking artesian aquifers in the
lacustrine sediments, contamination of deeper potable
aquifers is believed unlikely.
4-58
-------
TABLE 1
Site Name: Lakeview (Oregon)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 08/17/82 to 10/02/86
Page 1 of 5
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Arsenic 0 . 05 Background
Cross-gradient
On-Site
Down gradient
Barium 1 . 0 Background
Cross-gradient
On-Site
Down gradient
Number of
Analyses Percent
Formation of Number of Exceeding Exceeding
Completion Analyses Standard Standard
Sand or gravelly 25 2 8
sand, poorly
graded
Sand or gravelly 7
sand, poorly
graded
Sand or gravelly 19 7 36
sand, poorly
graded
Sand or gravelly 57 6 10
sand, poorly
graded
Sand or gravelly 6
sand, poorly
graded
Sand or gravelly 2
sand, poorly
graded
Sand or gravelly 8
sand, poorly
graded
Sand or gravelly 20
sand, poorly
graded
Maximum
Value
Obtained
(mg/1) I/
0.11
0.45
0.18
— -
_ —
4-59
-------
TABLE 1
Sito Name: Lakaview (Oregon)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 08/17/82 to 10/02/86
Page 2 of 5
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Cadmium 0.01 Background
Cross-gradient
On-Site
Down gradient
Chromium 0.05 Background
Cross-gradient
On-Site
Down gradient
Formation of Number of
Completion Analyses
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
25
7
18
55
12
6
15
46
Number of Maximum
Analyses Percent Value
Exceeding Exceeding Obtained
Standard Standard (ng/1) I/
_-_ ___ ___
1 5 0.04
3 5 0.31
___ — __ ___
3 6 0.08
4-60
-------
TABLE 1
Site Name: Lakeview (Oregon)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 08/17/82 to 10/02/86
Page 3 of 5
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Gross Alpha 15.0 pCi/1 Background
(excluding radon
and uranium)
Cross-gradient
On-Site
Down gradient
Lead 0.05 Background
Cross-gradient
On-Site
Down gradient
Number of Maximum
Analyses Percent Value
Formation of Number of Exceeding Exceeding Obtained
Completion Analyses Standard Standard (mg/1) I/
Sand or gravelly 1
sand, poorly
graded
Sand or gravelly 1
sand, poorly
graded
Sand or gravelly 1
sand, poorly
graded
Sand or gravelly 1 1 100 23.32
sand, poorly
graded
Sand or gravelly 9
sand, poorly
graded
Sand or gravelly 4
sand, poorly
graded
Sand or gravelly 14
sand, poorly
graded
Sand or gravelly 35
sand, poorly
graded
4-61
-------
TABLE 1
Site Name: Lakeview (Oregon)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 08/17/82 to 10/02/86
Page 4 of 5
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Mercury 0.002 Background
Cross-gradient
On-Site
Down gradient
Ra-226 + 5.0 pCi/1 Background
Ra-228 (Radium)
Cross-gradient
On-Site
Down gradient
Number of Maximum
Analyses Percent Value
Formation of Number of Exceeding Exceeding Obtained
Completion Analyses Standard Standard (mg/1) I/
Sand or gravelly 6
sand, poorly
graded
Sand or gravelly 2
sand, poorly
graded
Sand or gravelly 8
sand, poorly
graded
Sand or gravelly 20
sand, poorly
graded
Sand or gravelly 8
sand, poorly
graded
Sand or gravelly 4
sand, poorly
graded
Sand or gravelly 7
sand, poorly
graded
Sand or gravelly 30 1 3 76.0
sand, poorly
graded
4-62
-------
TABLE 1
Site Name: Lakeview (Oregon)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 08/17/82 to 10/02/86
Page 5 of 5
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Selenium 0 . 01 Background
Cross-gradient
On-Site
Down gradient
Silver 0.05 Background
Cross-gradient
On-Site
Down gradient
Number of Maximum
Analyses Percent Value
Formation of Number of Exceeding Exceeding Obtained
Completion Analyses Standard Standard (mg/1) I/
Sand or gravelly 10
sand, poorly
graded
Sand or gravelly 4
sand, poorly
graded
Sand or gravelly 16 3 18 0.243
sand, poorly
graded
Sand or gravelly 38
sand, poorly
graded
Sand or gravelly 5
sand, poorly
graded
Sand or gravelly 2
sand, poorly
graded
Sand or gravelly 7
sand, poorly
graded
Sand or gravelly 19
sand, poorly
graded
I/ Values are reported in mg/1 unless otherwise indicated.
— Standard not exceeded.
4-63
-------
TABLE 2
Site Name: Lakeview (Oregon)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 08/17/82 to 10/02/86
Page 1 of 8
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Chloride 250 Background
Cross-gradient
On-Site
Down gradient
Copper 1 . 0 Background
Cross-gradient
On-Site
Down gradient
Formation of Number of
Completion Analyses
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
25
7
18
57
10
4
15
36
Number of Maximum
Analyses Percent Value
Exceeding Exceeding Obtained
Standard Standard (ag/1) I/
—
6 33 3400
23 40 2400
__-
- —
4-64
-------
TABLE 2
Site Name: Lakeview (Oregon)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 08/17/82 to 10/02/86
Page 2 of 8
Constituent
Fluoride
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
1.4
Hydrogen Sulfide
0.05
Background
Cross-gradient
On-Site
Down gradient
Background
Cross-gradient
On-Site
Down gradient
Sand or gravelly 25
sand, poorly
graded
Sand or gravelly 7
sand, poorly
graded
Sand or gravelly 18
sand, poorly
graded
Sand or gravelly 57
sand, poorly
graded
Sand or gravelly 1
sand, poorly
graded
Sand or gravelly 1
sand, poorly
graded
Sand or gravelly 1
sand, poorly
graded
Sand or gravelly 1
sand, poorly
graded
10
40
45
44
78
4.7
6.27
8.8
4-65
-------
TABLE 2
Site Name: Lakeview (Oregon)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 08/17/82 to 10/02/86
Page 3 of 8
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Iron 0.30 Background
Cross-gradient
On-Site
Down gradient
Manganese 0 . 05 Background
Cross-gradient
On-Site
Down gradient
Formation of Number of
Completion Analyses
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
25
7
19
57
24
7
17
54
Number of
Analyses
Exceeding
Standard
___
6
12
9
7
12
49
Percent
Exceeding
Standard
___
31
21
37
100
70
90
Maximum
Value
Obtained
(mg/1) I/
___
27.0
9.14
0.26
8.30
25.0
24.7
4-66
-------
TABLE 2
Site Name: Lakeview (Oregon)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 08/17/82 to 10/02/86
Page 4 of 8
Constituent
Molybdenum
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
0.10
Nitrate 2/
44
Background
Cross-gradient
On-Site
Down gradient
Background
Cross-gradient
On-Site
Down gradient
Sand or gravelly 6
sand, poorly
graded
Sand or gravelly 2
sand, poorly
graded
Sand or gravelly 9
sand, poorly
graded
Sand or gravelly 27
sand, poorly
graded
Sand or gravelly 25
sand, poorly
graded
Sand or gravelly 7
sand, poorly
graded
Sand or gravelly 18
sand, poorly
graded
Sand or gravelly 57
sand, poorly
graded
16
11
11
0.11
0.32
0.44
4-67
-------
TABLE 2
Site Name: Lakeview (Oregon)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 08/17/82 to 10/02/86
Page 5 of 8
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
pH 3/ 6.5 to 8.5 Background
Cross-gradient
On-Site
Down gradient
Sulfate 250 Background
Cross-gradient
On-Site
Down gradient
Formation of Number of
Completion Analyses
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
Sand or gravelly
sand, poorly
graded
25
7
18
60
25
7
18
57
Number of
Analyses
Exceeding
Standard
4
3
9
4
8
35
Percent
Exceeding
Standard
16
16
15
57
44
61
Maximum
Value
Obtained
(mg/1) I/
6.02/8.90
5.70
5.58/9.30
650
7300
4700
4-68
-------
TABLE 2
Site Name: Lakeview (Oregon)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 08/17/82 to 10/02/86
Page 6 of 8
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Sulfide 0.05 Background
Cross-gradient
On-Site
Down gradient
Total Solids 500 Background
Cross-gradient
On-Site
Down gradient
Formation of Number of
Completion Analyses
Sand or gravelly 1
sand, poorly
graded
Sand or gravelly 1
sand, poorly
graded
Sand or gravelly 1
sand, poorly
graded
Sand or gravelly 1
sand, poorly
graded
Sand or gravelly 25
sand, poorly
graded
Sand or gravelly 7
sand, poorly
graded
Sand or gravelly 18
sand, poorly
graded
Sand or gravelly 57
sand, poorly
graded
Number of Maximum
Analyses Percent Value
Exceeding Exceeding Obtained
Standard Standard (ng/1) I/
11 43 992
4 57 1232
10 55 13,836
51 89 12,006
4-69
-------
TABLE 2
Site Name: Lakeview (Oregon)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 08/17/82 to 10/02/86
Page 7 of 8
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Uranium 4/ 0.044 Background
Cross-gradient
On-Site
Down gradient
Zinc 5.0 Background
Cross-gradient
On-Site
Down gradient
Number of Maximum
Analyses Percent Value
Formation of Number of Exceeding Exceeding Obtained
Completion Analyses Standard Standard (mg/1) I/
Sand or gravelly 7
sand, poorly
graded
Sand or gravelly 4
sand, poorly
graded
Sand or gravelly 9 1 11 0.10
sand, poorly
graded
Sand or gravelly 30
sand, poorly
graded
Sand or gravelly 11
sand, poorly
graded
Sand or gravelly 6
sand, poorly
graded
Sand or gravelly 14
sand, poorly
graded
Sand or gravelly 46
sand, poorly
graded
4-70
-------
TABLE 2 Page 8 of 8
Site Name: Lakeview (Oregon)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 08/17/82 to 10/02/86
Number of Maximum
Analyses Percent Value
Standard Hydraulic Flow Formation of Number of Exceeding Exceeding Obtained
Constituent (mg/1) I/ Relationship Completion Analyses Standard Standard (ng/1) I/
I/ Values are reported in mg/1 unless otherwise indicated.
2/ Concentrations of nitrate as nitrogen at a level of 10 mg/1 is equivalent to concentration of nitrate as nitrate at a
level of 44 mg/1. All analyses are reported in terms of nitrate as nitrate.
3/ pH reported in standard units.
4/ 30 pCi/1 of uranium is equivalent of 0.044 mg/1, assuming the bulk of uranium is U-238. All analyses are reported as
total uranium in mg/1.
Standard not exceeded.
4-71
-------
4.8 MEXICAN HAT, UTAH - SUMMARY OF WATER QUALITY
The Mexican Hat tailings site is in southeast Utah, approxi-
mately one mile south of Mexican Hat, Utah and the San Juan
River. Sampling of monitor wells indicate that the tailings
have contaminated approximately 80 million gallons of
groundwater. Seepage of contaminants into Gypsum Wash (the
major surface drainage area of the site) and subsequent
contamination of the San Juan River are of major concern.
Background water quality is unsuitable for most uses;
currently there are no groundwater withdrawals within the
site.
Of the standards contained in or referenced in 40 CFR
192.32(a), the limits for chromium, gross alpha, mercury,
radium and selenium were exceeded for some samples. Chromi-
um concentrations were higher in background samples in the
Rico Formation than in down gradient samples. Two out of 15
background analyses for radium and one out of 15 background
analyses for selenium exceeded the limit for the standard.
Two out of 14 background samples exceeded the standard for
gross alpha. One out of 2 down gradient analyses for
mercury exceeded the limit for the standard.
The contaminated groundwater appears to occur in perched
zones beneath and adjacent to the site. Because of the low
rate of movement of the perched water, over 500 years will
be required to flush the mobile contaminants from the
groundwater.
4-72
-------
TABLE 1
Site Name: Mexican Hat (Utah)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 04/10/85 to 11/01/85
Page 1 of 2
Constituent
Arsenic
Barium
Cadmium
Chromium
Gross Alpha
(excluding radon
and uranium)
Standard Hydraulic Flow
(mg/1) I/ Relationship
0 . 05 Background
On-Site
Down gradient
Down gradient
1 . 0 Background
On-Site
Down gradient
Down gradient
0.01 Background
On-Site
Down gradient
Down gradient
0.05 Background
On-Site
Down gradient
Down gradient
15.0 pCi/1 Background
On-Site
Down gradient
Down gradient
Formation of
Completion
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Number of
Analyses
15
1
2
1
15
1
2
1
15
1
2
1
15
1
2
1
14
1
1
1
Number of
Analyses
Exceeding
Standard
««M
5
1
1
2
Percent
Exceeding
Standard
:::
—
:::
33
50
100
14
Maximum
Value
Obtained
(mg/1) I/
:::
—
—
—
0.70
0.21
0.06
25.184
4-73
-------
TABLE 1
Site Name: Mexican Hat (Utah)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 04/10/85 to 11/01/85
Page 2 of 2
Constituent
Lead
Mercury
Ra-226 + Ra-228
(Radium)
Selenium
Silver
Standard Hydraulic Flow
(mg/1) I/ Relationship
0.05 Background
On-Site
Down gradient
Down gradient
0 . 002 Background
On-Site
Down gradient
Down gradient
5.0 pCi/1 Background
On-Site
Down gradient
Down gradient
0 . 01 Background
On-Site
Down gradient
Down gradient
0.05 Background
On-Site
Down gradient
Down gradient
Formation of
Completion
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Number of
Analyses
15
1
2
1
15
1
2
1
15
1
1
1
15
1
2
1
15
1
2
1
Number of
Analyses
Exceeding
Standard
...
...
...
___
...
...
1
— — —
2
---
1
___
--—
...
...
Percent
Exceeding
Standard
___
_..
...
...
...
...
50
...
13
- —
6
...
...
Maximum
Value
Obtained
(mg/1) I/
...
...
...
...
0.0024
...
5.40
— — —
0.05
— —
...
___
I/ Values are reported in mg/1 unless otherwise indicated.
Standard not exceeded.
4-74
-------
TABLE 2
Site Name: Mexican Hat (Utah)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included
plus Uranium and Molybdenum
Data Interval: 04/10/85 to 11/01/85
Pag* 1 of 3
in 40 CFR 192.32(a)
Constituent
Chloride
Copper
Fluoride
Hydrogen Sulfide
Iron
Standard Hydraulic Flow
(mg/1) I/ Relationship
250 Background
On-Site
Down gradient
Down gradient
1 . 0 Background
On-Site
Down gradient
Down gradient
1 . 4 Background
On-Site
Down gradient
Down gradient
0.05 Background
On-Site
Down gradient
Down gradient
0.30 Background
On-Site
Down gradient
Down gradient
Formation of
Completion
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Number of
Analyses
15
1
2
1
15
1
2
1
15
1
2
1
1
1
1
1
15
1
2
1
Number of
Analyses
Exceeding
Standard
1
:::
—
5
1
.— — —
Percent
Exceeding
Standard
50
:::
—
33
50
___
Maximum
Value
Obtained
(mg/1) I/
360
«»
1.5
9.2
«•_
4-75
-------
TABLE 2
Site Name: Mexican Hat (Utah)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included
plus Uranium and Molybdenum
Data Interval: 04/10/85 to 11/01/85
in 40 CFR 192.32(a)
Page 2 of 3
Constituent
Manganese
Molybdenum
Nitrate 2/
PH 3/
Sulfate
Standard Hydraulic Flow
(mg/1) I/ Relationship
0.05 Background
On-Site
Down gradient
Down gradient
0.10 Background
On-site
Down gradient
Down gradient
44 Background
On-Site
Down gradient
Down gradient
6.5 to 8.5 Background
On-Site
Down gradient
Down gradient
250 Background
On-Site
Down gradient
Down gradient
Formation of
Completion
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Number of
Analyses
15
1
2
1
15
1
2
1
15
1
2
1
15
1
2
1
15
1
2
1
Number of
Analyses
Exceeding
Standard
3
1
1
1
6
1
2
1
1
15
1
2
1
Percent
Exceeding
Standard
20
100
50
100
40
100
100
6
50
100
100
100
100
Maximum
Value
Obtained
(mg/1) I/
0.06
0.38
0.06
0.15
0.20
0.10
80.0
10.24
12.28
4090
3170
722
947
4-76
-------
TABLE 2
Site Name: Mexican Hat (Utah)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included
plus Uranium and Molybdenum
Data Interval: 04/10/85 to 11/01/85
in 40 CFR 192.32(a)
Page 3 of 3
Number of
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Sulfide 0.05
Total Solids 500
Uranium 4/ 0.044
Zinc 5.0
Background
On-Site
Down gradient
Down gradient
Background
On-Site
Down gradient
Down gradient
Background
On-Site
Down gradient
Down gradient
Background
On-Site
Down gradient
Down gradient
Maximum
Analyses Percent Value
Formation of Number of Exceeding Exceeding Obtained
Completion Analyses Standard Standard (mg/1) I/
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Siltstone
Rico
Rico
15
1
2
1
15
1
2
1
15
1
2
1
15
1
2
1
I/ Values are reported in mg/1 unless otherwise indicated.
2/ Concentrations of nitrate as nitrogen at a level of 10 mg/1 is equivalent to
level of 44 mg/1. All analyses are reported in terms of nitrate as nitrate.
3/ pH reported in standard units.
4/ 30 pCi/1 of uranium is equivalent of 0.044 mg/1, assuming the bulk of uranium
total uranium in mg/1.
Standard not exceeded.
15
1
2
15
1
2
1
2
1
100
100
100
100
100
100
100
13
100
concentration of nitrate
is U-238. All analyses
0.10
0.10
0.10
6550
1960
4250
1870
0.0512
0.602
0.0334
as nitrate at a
are reported as
4-77
-------
4.9 MONUMENT VALLEY, ARIZONA - SUMMARY OF WATER QUALITY
Major hydrostratigraphic units at the Monument Valley site
are alluvium and dune sand, the Shinarump Member of the
Chinle Formation, the Moenkopi Formation, and the DeChelly
Sandstone Member of the Cutler Formation. The alluvium,
Shinarump and the DeChelly Sandstone are aquifers. The
Moenkopi is an aquitard which separates the Shinarump from
the underlying DeChelly Sandstone.
The background water quality in all three of the aquifers is
good. Only the alluvial aquifer has been appreciably
affected by the tailings. The alluvial groundwater is
unconfined and ranges from approximately two feet to 45 feet
below the surface in the vicinity of the tailings.
Groundwater use near the site consists of two upgradient
alluvial wells which are used by local residents. Three
production wells are located on and down gradient of the
site. The production wells supplied water for the former
milling operations but are not presently used. Two seeps
east of the tailings site are discharges of alluvial ground-
water and are used for watering livestock. Sampling of
these wells and seeps has not revealed the presence of any
contamination from the tailings.
Chromium exceeded the standard in some samples from all
three down gradient aquifers. The down gradient alluvium
had the highest value for chromium, as well as, the highest
percentage of samples exceeding the standard.
The gross alpha standard was exceeded in background samples
of the Shinarump Formation and the down gradient alluvium
and DeChelly Formation samples. The highest values obtained
were from the down gradient alluvium, in which the maximum
value exceeded the standard by more than a factor of three.
One of nine radium background samples from the Shinarump
Formation exceeded the standard. This sample exceeded the
standard by a factor of less than two.
The contaminated groundwater is in an unconfined aquifer
with no nearby discharge point. Modeling indicates that the
mobile contaminant plume will dissipate within the aquifer
in approximately 120 years.
4-78
-------
TABLE 1
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 06/08/82 to 04/30/86
Page 1 of 10
Constituent
Arsenic
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
0.05 Background
Background
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
Alluvium 7
Shinarump member 10
of the Chinle
Formation
DeChelly member 9
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 44
Shinarump member 15
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
4-79
-------
TABLE 1
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 06/08/82 to 04/30/86
Page 2 of 10
Constituent
Barium
Standard
(mg/1) I/
1.0
Hydraulic Flow
Relationship
Background
Background
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
Alluvium 6
Shinarump member 9
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
of the Chinle
Formation
DeChelly member 7
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 34
Shinarump member 12
of the Chinle
Formation
DeChelly member 4
of the Cutler
Formation
4-80
-------
TABLE 1
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 06/08/82 to 04/30/86
Page 3 of 10
Constituent
Cadmium
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
0.01
Background
Background
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
Alluvium 6
Shinarump member 10
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 44
Shinarump member 15
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
4-81
-------
TABLE 1
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 06/08/82 to 04/30/86
Page 4 of 10
Constituent
Chromium
Standard
(mg/1) I/
0.05
Hydraulic Flow
Relationship
Background
Background
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
Alluvium 6
Shinarump member 10
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 44
Shinarump member 15
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
12
1
27
6
25
0.09
0.07
0.07
4-82
-------
TABLE 1
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 06/08/82 to 04/30/86
Page 5 of 10
Constituent
Gross Alpha
(excluding radon
and uranium)
Standard
(mg/1) I/
15.0 pCi/1
Hydraulic Flow
Relationship
Background
Background
Formation of
Completion
Number of
Analyses
Alluvium
Shinarump member
of the Chinle
6
10
Number of
Analyses
Exceeding
Standard
1
Percent
Exceeding
Standard
10
Maximum
Value
Obtained
(mg/1) I/
17.104
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 44
Shinarump member 15
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
15
12
45.968
16.372
4-83
-------
TABLE 1
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 06/08/82 to 04/30/86
Page 6 of 10
Constituent
Lead
Standard
(mg/1) I/
0.05
Hydraulic Flow
Relationship
Background
Background
Formation
Completion
Alluvium
Shinarump
of Number of
Analyses
6
member 10
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 44
Shinarump member 15
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
4-84
-------
TABLE 1
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 06/08/82 to 04/30/86
Page 7 of 10
Constituent
Mercury
Standard
(mg/1) I/
0.002
Hydraulic Flow
Relationship
Background
Background
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
Alluvium 6
Shinarump member 9
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
of the Chinle
Formation
DeChelly member 7
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 34
Shinarump member 12
of the Chinle
Formation
DeChelly member 4
of the Cutler
Formation
4-85
-------
TABLE 1
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 06/08/82 to 04/30/86
Page 8 of 10
Constituent
Ra-226 + Ra-228
(Radium)
Standard
(mg/1) I/
5.0 pci/l
Hydraulic Flow
Relationship
Background
Background
Formation of
Completion
Number of
Analyses
Alluvium 6
Shinarump member 9
Number of
Analyses
Exceeding
Standard
1
Percent
Exceeding
Standard
11
Maximum
Value
Obtained
(mg/1) I/
8.8
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
of the Chinle
Formation
DeChelly member 7
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 34
Shinarump member 12
of the Chinle
Formation
DeChelly member 3
of the Cutler
Formation
4-86
-------
TABLE 1
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 06/08/82 to 04/30/86
Page 9 of 10
Constituent
Selenium
Standard
(mg/1) I/
0.01
Hydraulic Flow
Relationship
Background
Background
Formation of
Completion
Number of
Analyses
Alluvium
Shinarump member
7
10
Number of
Analyses
Exceeding
Standard
— _u
Percent
Exceeding
Standard
•V — —
Maximum
Value
Obtained
(mg/1) I/
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
of the Chinle
Formation
DeChelly member 9
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 44
Shinarump member 15
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
4-87
-------
TABLE 1
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 06/08/82 to 04/30/86
Page 10 of 10
Constituent
Silver
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
0.05 Background
Background
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
Alluvium 6
Shinarump member 9
of the Chinle
Formation
DeChelly member 7
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 34
Shinarump member 12
of the Chinle
Formation
DeChelly member 4
of the Cutler
Formation
I/ Values are reported in mg/1 unless otherwise indicated.
Standard not exceeded.
4-88
-------
TABLE 2
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 06/08/82 to 04/30/86
Page 1 of 15
Constituent
Chloride
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
250
Background
Background
Background
Cross-gradient
Cross-gradient
Cros s-grad i ent
On-Site
Down gradient
Down gradient
Down gradient
Alluvium 7
Shinarump member 10
of the Chinle
Formation
DeChelly member 9
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 44
Shinarump member 15
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
4-89
-------
TABLE 2
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 06/08/82 to 04/30/86
Page 2 of 15
Constituent
Copper
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
1.0
Background
Background
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
Alluvium 6
Shinarump member 9
of the Chinle
Formation
DeChelly member 7
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 34
Shinarump member 12
of the Chinle
Formation
DeChelly member 4
of the Cutler
Formation
4-90
-------
TABLE 2
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 06/08/82 to 04/30/86
Page 3 of 15
Constituent
Fluoride
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
1.4
Background
Background
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
Alluvium 7
Shinarump member 9
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 34
Shinarump member 12
of the Chinle
Formation
DeChelly member 4
of the Cutler
Formation
4-91
-------
TABLE 2
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uraniuma and Molybdenum
Data Interval: 06/08/82 to 04/30/86
Page 4 of 15
Constituent
Hydrogen Sulfide
Standard
(mg/1) I/
0.05
Hydraulic Flow
Relationship
Background
Background
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
Alluvium 1
Shinarump member 1
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
of the Chinle
Formation
DeChelly member 1
of the Cutler
Formation
Alluvium 1
Shinarump member 1
of the Chinle
Formation
DeChelly member 1
of the Cutler
Formation
DeChelly member 1
of the Cutler
Formation
Alluvium 1
Shinarump member 1
of the Chinle
Formation
DeChelly member 1
of the Cutler
Formation
4-92
-------
TABLE 2
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 06/08/82 to 04/30/86
Page 5 of 15
Constituent
Iron
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
0.30 Background
Background
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
Alluvium 7
Shinarump member 10
of the Chinle
Formation
DeChelly member 9
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 44
Shinarump member 15
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
10
0.33
0.31
4-93
-------
TABLE 2
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 06/08/82 to 04/30/86
Page 6 of 15
Constituent
Manganese
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
0.05 Background
Background
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
Alluvium 6
Shinarump member 10
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 44
Shinarump member 15
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
70
0.10
50
50
0.09
0.21
20
7
44
46
37
0.58
0.17
0.11
4-94
-------
TABLE 2
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 06/08/82 to 04/30/86
Page 7 of 15
Constituent
Molybdenum
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
0.10 Background
Background
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
Alluvium 7
Shinarump member 10
of the Chinle
Formation
DeChelly member 9
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 7
of the Cutler
Formation
Alluvium 44
Shinarump member 15
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
1
4
2
1
14
40
44
50
50
83
37
14
84
93
100
0.11
0.22
0.19
0.19
0.16
0.21
0.35
0.25
0.24
4-95
-------
TABLE 2
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 06/08/82 to 04/30/86
Page 8 of 15
Constituent
Nitrate 2/
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
44
Background
Background
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient:
Down gradient
Down gradient
Alluvium 6
Shinarump member 10
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 44
Shinarump member 15
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
15
34
1200
4-96
-------
TABLE 2
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 06/08/82 to 04/30/86
Page 9 of 15
Constituent
PH 3/
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
6.5 to 8.5
Background
Background
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
Alluvium 7
Shinarump member 10
of the Chinle
Formation
DeChelly member 9
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 44
Shinarump member 15
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
22
9.36
1
1
2
6
50
9.68
8.65
9.89
4-97
-------
TABLE 2
Site Name: Monument, Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 06/08/82 to 04/30/86
Page 10 of 15
Constituent
Sulfate
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
250
Background
Background
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
Alluvium 7
Shinarump member 10
of the Chinle
Formation
DeChelly member 9
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 44
Shinarump member 15
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
28
63
3130
4-98
-------
TABLE 2
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 06/08/82 to 04/30/86
Page 11 of 15
Constituent
Sulfide
Standard
(mg/1) I/
0.05
Hydraulic Flow
Relationship
Background
Background
Formation of
Completion
Number of
Analyses
Alluvium 6
Shinarump member 9
Number of
Analyses
Exceeding
Standard
3
7
Percent
Exceeding
Standard
50
77
Maximum
Value
Obtained
(mg/1) I/
0.10
0.10
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
of the Chinle
Formation
DeChelly member 7
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 34
Shinarump member 12
of the Chinle
Formation
DeChelly member 5
of the Cutler
Formation
2
1
28
7
57
50
50
16
75
82
58
100
0.10
0.10
0.10
0.10
0.10
0.10
0.10
0.10
4-99
-------
TABLE 2
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 06/08/82 to 04/30/86
Page 12 of 15
Constituent
Total Solids
Standard
(mg/1) I/
500
Hydraulic Flow
Relationship
Background
Background
Formation of
Completion
Number of
Analyses
Alluvium 7
Shinarump member 10
Number of
Analyses
Exceeding
Standard
2
Percent
Exceeding
Standard
28
Maximum
Value
Obtained
(mg/1) I/
626
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
of the Chinle
Formation
DeChelly member 9
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 44
Shinarump member 15
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
28
6
63
40
25
5590
730
563
4-100
-------
TABLE 2
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 06/08/82 to 04/30/86
Page 13 of 15
Constituent
Uranium 4/
Standard
(mg/1)
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
0.044 Background
Background
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
Alluvium 7
Shinarump member 10
of the Chinle
Formation
DeChelly member 9
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 44
Shinarump member 15
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
13
0.0514
4-101
-------
TABLE 2
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 06/08/82 to 04/30/86
Page 14 of 15
Constituent
Zinc
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
5.0
Background
Background
Background
Cross-gradient
Cross-gradient
Cross-gradient
On-Site
Down gradient
Down gradient
Down gradient
Alluvium 6
Shinarump member 10
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 4
Shinarump member 2
of the Chinle
Formation
DeChelly member 6
of the Cutler
Formation
DeChelly member 8
of the Cutler
Formation
Alluvium 44
Shinarump member 15
of the Chinle
Formation
DeChelly member 8
of the Cutler
Formation
4-102
-------
TABLE 2 Page 15 of 15
Site Name: Monument Valley (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybedum
Data Interval: 06/08/82 to 04/30/86
Constituent
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
I/ Values are reported in mg/1 unless otherwise indicated.
2/ Concentrations of nitrate as nitrogen at a level of 10 mg/1 is equivalent to concentration of nitrate as nitrate at a
level of 44 mg/1. All analyses are reported in terms of nitrate as nitrate.
3/ pH reported in standard units.
4/ 30 pCi/1 of uranium is equivalent of 0.044 mg/1, assuming the bulk of uranium is U-238. All analyses are reported as
total uranium in mg/1.
Standard not exceeded.
4-103
-------
4.10 RIVERTON, WYOMING - SUMMARY OF WATER QUALITY
The Riverton process site lies on the floodplain of the Wind
and Little Wind Rivers. The site rests on, in descending
order, recent alluvium and beds of the Wind River Formation.
There are two aquifers in the site vicinity; the water table
(unconfined)aquifer consisting of alluvium and the uppermost
sandstone of the Wind River Formation (2) the confined
aquifer consisting of deeper sandstone beds. Contamination
is restricted largely to the unconfined aquifer. Histor-
ically the unconfined aquifer within the plume area has had
limited use; currently, the aquifer is not being used in
this area. The confined aquifer does not appear to be
contaminated.
Groundwater sampling indicated that limits of concentration
of gross alpha were exceeded. The one on-site gravel
analyzed for gross alpha exceeded the standard by'more than
a factor of 17. Concentrations of arsenic, chromium,
barium, silver, cadmium, mercury, radium, lead and selenium
were below the limits for the standard.
Groundwater discharges to the Little Wind River, approxi-
mately 3000 feet from the site. Modeling indicates that it
will take 45 to 65 years for the mobile contaminants to
completely flush from the unconfined aquifer. Based on the
present location of the molybdenum plume relative to the
sulfate plume, it may take 200 to 300 years to flush molyb-
denum from the system.
4-104
-------
TABLE 1 Page 1 of 5
Site Name: Riverton (Wyoming)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 12/02/83 to 06/05/85
Number of Maximum
Analyses Percent Value
Standard Hydraulic Flow Formation of Number of Exceeding Exceeding Obtained
Constituent (mg/1) !/ Relationship Completion Analyses Standard Standard (mg/1) I/
Arsenic 0.05 Background Gravel or sandy 8
gravel, poorly
graded
On-Site Gravel or sandy 3
gravel, poorly
graded
On-Site Sandstone 21
Down gradient Gravel or sandy 1
gravel, poorly
graded
Down gradient Sandstone 3
Barium 1.0 Background Gravel or sandy 8
gravel, poorly
graded
On-Site Gravel or sandy 3
gravel, poorly
graded
On-Site Sandstone 21
Down gradient Gravel or sandy 1
gravel, poorly
graded
Down gradient Sandstone 3
4-105
-------
TABLE 1
Site Name: Riverton (Wyoming)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 12/02/83 to 06/05/85
Page 2 of 5
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Cadmium 0.01 Background
On-Site
On-Site
Down gradient
Down gradient
Chromium 0 . 05 Background
On-Site
On-Site
Down gradient
Formation of Number of
Completion Analyses
Gravel or sandy
gravel, poorly
graded
Gravel or sandy
gravel , poorly
graded
Sandstone
Gravel or sandy
gravel, poorly
graded
Sandstone
Gravel or sandy
gravel , poorly
graded
Gravel or sandy
gravel , poorly
graded
Sandstone
Gravel or sandy
8
3
21
1
3
8
3
21
1
Number of Maximum
Analyses Percent Value
Exceeding Exceeding Obtained
Standard Standard (mg/1) I/
— ... — -
___
— — — — — — __—
___ ___
___ ___
Down gradient
gravel, poorly
graded
Sandstone
4-106
-------
TABLE 1
Site Name: Riverton (Wyoming)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 12/02/83 to 06/05/85
Page 3 of 5
Constituent
Gross Alpha
(excluding radon
and uranium)
Lead
Standard Hydraulic Flow
(mg/1) I/ Relationship
15.0 pCi/1 Background
On-Site
On-Site
Down gradient
Down gradient
0.05 Background
On-Site
On-Site
Down gradient
Number of Maximum
Analyses Percent Value
Formation of Number of Exceeding Exceeding Obtained
Completion Analyses Standard Standard (mg/1) I/
Gravel or sandy
gravel , poorly
graded
Gravel or sandy
gravel , poorly
graded
Sandstone
Gravel or sandy
gravel , poorly
graded
Sandstone
Gravel or sandy
gravel, poorly
graded
Gravel or sandy
gravel , poorly
graded
Sandstone
Gravel or sandy
9
1 1 100 260.8
10 1 10 65.2
1
3 — —— -.«.— «__
8
3
21
1
Down gradient
gravel, poorly
graded
Sandstone
4-107
-------
TABLE 1
Site Name: Riverton (Wyoming)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 12/02/83 to 06/05/85
Page 4 of 5
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Mercury 0.002 Background
On-Site
On-Site
Down gradient
Down gradient
Number of Maximum
Analyses Percent Value
Formation of Number of Exceeding Exceeding Obtained
Completion Analyses Standard Standard (mg/1) I/
Gravel or sandy
gravel, poorly
graded
Gravel or sandy
gravel , poorly
graded
Sandstone
Gravel or sandy
gravel , poorly
graded
Sandstone
8
3
16
1fu _,
Ra-226 + Ra-228
(Radium)
5.0 pCi/1 Background
On-Site
On-Site
Down gradient
Down gradient
Gravel or sandy
gravel, poorly
graded
Gravel or sandy
gravel, poorly
graded
Sandstone
Gravel or sandy
gravel, poorly
graded
Sandstone
2 2/
7
1
4-108
-------
TABLE 1
Site Name: Riverton (Wyoming)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 12/02/83 to 06/05/85
Page 5 of 5
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Selenium 0.01 Background
On-Site
On-Site
Down gradient
Down gradient
Number of Maximum
Analyses Percent Value
Formation of Number of Exceeding Exceeding Obtained
Completion Analyses Standard Standard (mg/1) I/
Gravel or sandy 8
gravel, poorly
graded
Gravel or sandy 3
gravel, poorly
graded
Sandstone 21
Gravel or sandy 1
gravel , poorly
graded
Sandstone 3
Silver
0.05 Background
On-Site
On-Site
Down gradient
Down gradient
Gravel or sandy
gravel, poorly
graded
Gravel or sandy
gravel, poorly
graded
Sandstone
Gravel or sandy
gravel, poorly
graded
Sandstone
16
1
I/ Values are reported in mg/1 unless otherwise indicated.
2/ Analyses for Ra-226 only.
Standard not exceeded.
4-109
-------
TABLE 2
Site Name: Rivarton (Wyoming)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included
plus Uranium and Molybdenum
Data Interval: 12/02/83 to 06/05/85
Page 1 of 8
in 40 CFR 192.32(a)
Constituent
Chloride
Standard Hydraulic Flow
(mg/1) I/ Relationship
250 Background
On-Site
.On-Site
Down gradient
Down gradient
Formation of Number of
Completion Analyses
Gravel or sandy 9
gravel , poorly
graded
Gravel or sandy 3
gravel , poorly
graded
Sandstone 21
Gravel or sandy 1
gravel , poorly
graded
Sandstone 2
Number of
Analyses
Exceeding
Standard
Maximum
Percent Value
Exceeding Obtained
Standard (mg/1) I/
Copper
1.0 Background
On-Site
On-Site
Down gradient
Down gradient
Gravel or sandy
gravel, poorly
graded
Gravel or sandy
gravel, poorly
graded
Sandstone
Gravel or sandy
gravel, poorly
graded
Sandstone
21
1
4-110
-------
TABLE 2
Site Name: Riverton (Wyoming)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 12/02/83 to 06/05/85
Page 2 of 8
Constituent
Fluoride
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
Hydrogen Sulfide
1.4 Background
On-Site
On-Site
Down gradient
Down gradient
0.05 Background
On-Site
On-Site
Down gradient
Down gradient
Gravel or sandy 9
gravel, poorly
graded
Gravel or sandy 3
gravel, poorly
graded
Sandstone 16
Gravel or sandy 1
gravel, poorly
graded
Sandstone 2
Gravel or sandy 1
gravel, poorly
graded
Gravel or sandy 1
gravel, poorly
graded
Sandstone 1
Gravel or sandy 1
gravel, poorly
graded
Sandstone 1
4-111
-------
TABLE 2
Site Name: Riverton (Wyoming)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 12/02/83 to 06/05/85
Page 3 of 8
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Iron 0.30 Background
On-Site
On-site
Down gradient
Down gradient
Manganese 0.05 Background
On-Site
On-Site
Down gradient
Formation of Number of
Completion Analyses
Gravel or sandy
gravel , poorly
graded
Gravel or sandy
gravel , poorly
graded
Sandstone
Gravel or sandy
gravel , poorly
graded
Sandstone
Gravel or sandy
gravel , poorly
graded
Gravel or sandy
gravel , poorly
graded
Sandstone
Gravel or sandy
8
3
21
1
3
8
3
21
1
Number of Maximum
Analyses Percent Value
Exceeding Exceeding Obtained
Standard Standard (mg/1) I/
— - _--
4 19 0.75
—
— —— — — — — ._
8 100 2.26
3 100 0.23
21 100 5.20
1 100 1.05
Down gradient
gravel, poorly
graded
Sandstone
4-112
-------
TABLE 2
Site Name: Riverton (Wyoming)
Data Evaluation: Site Hater Quality Compared to U.S. EPA Standards Not Included
plus Uranium and Molybdenum
Data Interval: 12/02/83 to 06/05/85
Page 4 of 8
in 40 CFR 192.32(a)
Constituent
Molybdenum
Standard
(ng/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
0.10 Background
On-Site
On-Site
Down gradient
Nitrate 2/
44
Down gradient
Background
On-Site
On-Site
Down gradient
Down gradient
Gravel or sandy 8
gravel, poorly
graded
Gravel or sandy 3
gravel, poorly
graded
Sandstone 21
Gravel or sandy 1
gravel, poorly
graded
Sandstone 3
Gravel or sandy 9
gravel, poorly
graded
Gravel or sandy 3
gravel, poorly
graded
Sandstone 21
Gravel or sandy 1
gravel, poorly
graded
Sandstone 3
19
1.69
4-113
-------
TABLE 2
Site Name: Riverton (Wyoming)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 12/02/83 to 06/05/85
Page 5 of 8
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
pH 3/ 6.5 to 8.5 Background
On-Site
On-Site
Down gradient
Down gradient
Sulfate 250 Background
On-Site
On-Site
Down gradient
Number of Maximum
Analyses Percent Value
Formation of Number of Exceeding Exceeding Obtained
Completion Analyses Standard Standard (mg/1) I/
Gravel or sandy
gravel, poorly
graded
Gravel or sandy
gravel , poorly
graded
Sandstone
Gravel or sandy
gravel , poorly
graded
Sandstone
Gravel or sandy
gravel , poorly
graded
Gravel or sandy
gravel , poorly
graded
Sandstone
Gravel or sandy
12 18 9.35
1
15
3
3 3 100 12,'. 2 6
9 2 22 376
3 3 100 577
21 19 90 747
1 1 100 461
Down gradient
gravel, poorly
graded
Sandstone
50
286
4-114
-------
TABLE 2
Site Name: Riverton (Wyoming)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 12/02/83 to 06/05/85
Page 6 of 8
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Sulfide 0.05 Background
On-Site
On-Site
Down gradient
Down gradient
Total Solids 500 Background
On-Site
On-Site
Down gradient
Formation of Number of
Completion Analyses
Gravel or sandy
gravel , poorly
graded
Gravel or sandy
gravel , poorly
graded
Sandstone
Gravel or sandy
gravel , poorly
graded
Sandstone
Gravel or sandy
gravel , poorly
graded
Gravel or sandy
gravel, poorly
graded
Sandstone
Gravel or sandy
9
1
7
1
3
9
3
21
1
Number of
Analyses
Exceeding
Standard
9
- —
7
1
3
2
3
19
1
Percent
Exceeding
Standard
100
100
100
100
22
100
90
100
Maximum
Value
Obtained
(mg/1) I/
0.10
— — —
0.10
0.10
0.10
950
1410
1450
1100
Down gradient
gravel, poorly
graded
Sandstone
100
1172
4-115
-------
TABLE 2
Site Name: Riverton (Wyoming)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 12/02/83 to 06/05/85
Page 7 of 8
Constituent
Uranium 4/
Standard
(mg/1) I/
Hydraulic Flow
Relationship
Formation of
Completion
Number of
Analyses
Number of
Analyses
Exceeding
Standard
Percent
Exceeding
Standard
Maximum
Value
Obtained
(mg/1) I/
0.044
Zinc
5.0
Background
On-Site
On-Site
Down gradient
Down gradient
Background
On-Site
On-Site
Down gradient
Down gradient
Gravel or sandy 9
gravel, poorly
graded
Gravel or sandy 2
gravel, poorly
graded
Sandstone 13
Gravel or sandy 1
gravel, poorly
graded
Sandstone 3
Gravel or sandy 8
gravel, poorly
graded
Gravel or sandy 3
gravel, poorly
graded
Sandstone 21
Gravel or sandy 1
gravel, poorly
graded
Sandstone 3
100
15
0.415
0.305
4-116
-------
TABLE 2 Page 8 of 8
Site Name: Riverton (Wyoming)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 12/02/83 to 06/05/85
Number of Maximum
Analyses Percent Value
Standard Hydraulic Flow Formation of Number of Exceeding Exceeding Obtained
Constituent (mg/1) I/ Relationship Completion Analyses Standard Standard (mg/1) I/
I/ Values are reported in mg/1 unless otherwise indicated.
2/ Concentrations of nitrate as nitrogen at a level of 10 mg/1 is equivalent to concentration of nitrate as nitrate at a
level of 44 mg/1. All analyses are reported in terms of nitrate as nitrate.
3/ pH reported in standard units.
4/ 30 pCi/1 of uranium is equivalent of 0.044 mg/1, assuming the bulk of uranium is U-238. All analyses are reported as
total uranium in mg/1.
Standard not exceeded.
4-117
-------
4.11 SALT LAKE CITY, UTAH - SUMMARY OF WATER QUALITY
The groundwater regime at the Vitro site is generally
characterized by two aquifer systems, a near-surface
unconfined system and a deeper confined system. Near the
site, both aquifers flow generally to the west-northwest.
The unconfined aquifer discharges into local surface water
courses.
Water in the unconfined aquifer is of brackish quality with
high total dissolved solids, generally 2000 ppm or greater,
and sulfates on the order of 800 ppm or greater. Due to its
poor quality and low yields, this water has only very
limited use. Water in the confined aquifer generally has
dissolved solids concentrations of about 300 ppm and a
sulfate content of about 20 ppm. This aquifer is an impor-
tant source of water for domestic, agricultural and indus-
trial uses in the Salt Lake Valley.
In the unconfined aquifer, arsenic, iron and manganese
values exceeded standards in some up-, cross- and down-
gradient samples, with no clear trend evident. Gross alpha
and radium (Ra-226 and 228) values also exceeded standards
in some up-, cross- and downgradient samples, with signif-
icantly higher values in downgradient samples. Some samples
from up-, cross- and downgradient exceeded standards for
total dissolved solids, chloride and sulfate, with a larger
percentage of samples exceeding standards and somewhat
higher values in downgradient samples.
In the confined aquifer, some downgradient samples exceeded
standards for total dissolved solids and sulfate. Iron
values exceeded standards in up-, cross- and downgradient
samples, but the percentage of samples exceeding standards
was higher and the extent of the difference between the
measured values and the standards was greater in the down-
gradient samples.
The unconfined groundwater aquifer discharges to the Jordan
River and Mill Creek. Contaminant plumes have not been
modeled.
4-118
-------
TABLE 1
Site Name: Salt Lake City, Utah
Data. Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 1982 and 1983
Page 1 of 2
Standard
Constituent (mg/1) I/
Arsenic 0.05
Barium 1.0
Cadmium 0.01
Chromium 0.05
Gross Alpha 15.0 pCi/1
(excluding radon
and uranium)
Lead 0.05
Aquifer
Unconfined
Confined
Unconfined
Confined
Unconfined
Confined
Unconfined
Confined
Unconfined
Confined
Unconfined
Confined
Hydraulic Flow
Relationship
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Number of
Analyses
14
8
29
3
3
14
14
8
29
3
3
13
14
8
29
3
3
13
14
8
29
3
3
13
10
8
29
3
2
13
14
8
29
3
3
13
Number of
Analyses
Exceeding
Standard
11
4
— _
~~~
---
— _
1
---
6
3
24
2
1
4
2
Percent
Exceeding
Standard
79
— -
14
---
_««
__—
_— —
12
---
---
60
37
83
67
50
31
14
Maximum
Value
Obtained
(mg/1) I/
0.245
---
0.5
-__
---
— « «
---
— -
_•._
---
— •»_
0.08
---
600
85.2
1181
30
30
100
0.3
---
4-119
-------
TABLE 1
Site Name: Salt Lake City, Utah
Data Evaluation: Site Water Quality Compared to U.S.
Data Interval: 1982 and 1983
Page 2 of 2
EPA Standards from 40 CFR 192.32(a)
Standard
Constituent (mg/1) I/ Aquifer
Mercury 0.002 Unconfined
Confined
Ra-226 + Ra-228 5.0 pCi/1 Unconfined
( Radium)
Confined
Selenium 0.01 Unconfined
Confined
Silver 0.05 Unconfined
Confined
Hydraulic Flow 1
Relationship
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradien
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Number of
Analyses
14
8
29
3
3
13
10
8
27
3
2
12
14
8
29
3
3
13
14
8
29
3
3
13
Number of
Analyses
Exceeding
Standard
—
—
1
—
—
— -
1
3
5
-__
1
1
_ —
-__
---
Percent
Exceeding
Standard
3
---
10
37
18
___
50
8
___
---
---
Maximum
Value
Obtained
(mg/1) I/
—
—
0.003
---
14
12.5
114
___
5.1
9.1
___
___
___
---
I/ Values are reported in mg/1 unless otherwise indicated.
— Standard not exceeded.
4-120
-------
TABLE 2
Site Name: Salt Lake City, Utah
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 1982 and 1983
Page 1 of 3
Standard
Constituent (mg/1) \/
Chloride 250
Copper 1 . 0
Fluoride 1.4
Hydrogen Sulfide 0.05
Iron 0.3
Manganese 0.05
Aquifer
Unconfined
Confined
Unconfined
Confined
Unconfined
Confined
Unconfined
Confined
Unconfined
Confined
Unconfined
Confined
Hydraulic Flow 1
Relationship ;
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Number of
Analyses
9
5
21
3
2
14
14
8
29
3
3
13
1
4
5
1
1
4
1
4
6
1
1
4
15
8
35
3
3
17
8
6
18
1
2
10
Number of
Analyses
Exceeding
Standard
5
5
17
_ —
5
___
— _
___
5
___
___
2
1
1
8
6
25
1
2
11
7
6
17
---
2
10
Percent
Exceeding
Standard
56
100
81
— -
36
— _«
- —
100
— — ..
___
33
100
25
53
75
71
33
67
65
87
100
94
---
100
100
Maximum
Value
Obtained
(mg/1) I/
4900
2883
5400
---
410
---
___
---
---
«_—
---
6.1
__ _
___
0.08
0.09
0.07
70
44
58
0.61
0.92
4.6
1.6
1.85
4.02
---
1.5
0.60
4-121
-------
TABLE 2
Site Name: Salt Lake City, Utah
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 1982 and 1983
Page 2 of 3
Standard
Constituent (mg/1) I/
Molybdenum 0 . 10
Nitrate 2/ 44
pH y 6.5 to 8.5
Sulfate 250
Total Solids 500
Uranium 4/ 0.044
Aquifer
Unconfined
Confined
Unconfined
Confined
Unconfined
Confined
Unconfined
Confined
Unconfined
Confined
Unconfined
Confined
Hydraulic Flow Number of
Relationship Analyses
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
Upgradient
Crossgradient
Downgradient
14
8
29
3
3
13
5
6
12
3
2
6
12
6
25
3
2
14
9
5
21
3
2
14
12
5
25
3
2
15
11
8
33
3
2
16
Number of
Analyses
Exceeding
Standard
_ —
1
—
—
---
— _
—
—
—
1
—
—
—
---
4
5
18
5
10
5
22
11
1
24
Percent
Exceeding
Standard
—
—
3
---
___
17
- —
44
100
86
36
83
100
88
73
12
73
Maximum
Value
Obtained
(mg/1) I/
0
---
___
---
4300
2000
7800
590
16100
6002
21000
1800
31.
2.
.2
1
24
4-122
-------
TABLE 2 Page 3 of 3
Site Name: Salt Lake City, Utah y
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 1982 and 1983
Standard
Constituent (mg/1) I/
Zinc 5 . 0
I/ Values are reported in mg/1
2/ Concentrations of nitrate as
Hydraulic Flow
Aquifer Relationship
Unconfined Upgradient
Crossgradient
Downgradient
Confined Upgradient
Crossgradient
Downgradient
unless otherwise indicated.
nitrogen at a level of 10 mg/1
Number of Maximum
Analyses Percent Value
Number of Exceeding Exceeding Obtained
Analyses Standard Standard (mg/1) I/
14
8
29 1 3
3
3
13
is equivalent to concentration of nitrate as
110
nitrate
at a level of 44 mg/1. All analyses are reported in terms of nitrate as nitrate.
3_/ pH reported in standard units.
4_/ 30 pCi/1 of uranium is equivalent of 0.044 mg/1, assuming the bulk of uranium'is U-238. All analyses are
reported as total uranium in mg/1.
Standard not exceeded.
4-123
-------
4.12 SHIPROCK, NM - SUMMARY OF WATER QUALITY
The Shiprock site is in northwestern New Mexico and rests on
the escarpment above the floodplain of the San Juan River.
The remedial action is complete. The underlying groundwater
(divided into two units) is definitely contaminated.
Groundwater in the floodplain unit has been used and is
potentially useable in the future; contamination in the
floodplain appears to be relict, i.e., from past discharges.
A key issue is the extent and characteristics of the flood-
plain contamination. The second groundwater unit is perched
within the soils and fractured Mancos Shale on the escarp-
ment above the floodplain.
Chromium, selenium and silver exceeded the standard for some
samples. Eight out of 29 analysis for chromium down gradi-
ent samples exceed the standard. One of 29 down gradient
samples exceeded the standard for silver. Thirteen of 77
down gradient selenium samples exceeded standards. Arsenic,
barium, cadmium, gross alpha, lead, mercury, and radium
concentrations are within limits of the standards.
Contaminated water occurs in the floodplain. Groundwater in
the alluvium discharges to the San Juan River. The contami-
nant plume has not been modeled; existing data show little
if any flushing of contaminants in the alluvium.
4-124
-------
TABLE 1
Site Name: Shiprock (New Mexico)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 10/16/84 to 09/20/86
Page 1 of 2
Constituent
Arsenic
Barium
Cadmium
Chromium
Gross Alpha
(excluding radon
and uranium)
Lead
Mercury
Standard
(mg/1) I/
0.05
1.0
0.01
0.05
15.0 pCi/1
0.05
0.002
Hydraulic Flow
Relationship
Upgradient
Down gradient
Upgradient
Down gradient
Upgradient
Down gradient
Upgradient
Down gradient
Upgradient
Down gradient
Upgradient
Down gradient
Upgradient
Down gradient
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Number of
Analyses
2
29
2
29
2
77
2
29
1
1
2
29
2
29
Number of
Analyses
Exceeding
Standard
8
:::
Maximum
Percent Value
Exceeding Obtained
Standard (mg/1) I/
27 0.11
— — — — —
::: :::
4-125
-------
TABLE 1
Site Name: Shiprock (New Mexico)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 10/16/84 to 09/20/86
Page 2 of 2
Constituent
Ra-226 + Ra-228
(Radium)
Selenium
silver
Standard
(mg/1) I/
5.0 pCi/1
0.01
0.05
Hydraulic Flow
Relationship
Upgradient
Down gradient
Upgradient
Down gradient
Upgradient
Down gradient
I/ Values are reported in mg/1 unless otherwise
2/ Analyses for Ra-226 only.
Standard not exceeded.
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
indicated.
Number of
Analyses
2 2/
23
2
77
2
29
Number of
Analyses
Exceeding
Standard
13
1
Percent
Exceeding
Standard
16
3
Maximum
Value
Obtained
(mg/1) I/
0.91
0.10
4-126
-------
TABLE 2 Page 1 of 2
Site Name: Shiprock (New Mexico)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molydbenum
Data Interval: 10/16/84 to 09/20/86
Constituent
Chloride
Copper
Fluoride
Hydrogen Sulfide
Iron
Manganese
Molybdenum
Nitrate 2/
Standard
(mg/1) I/
250
1.0
1.4
0.05
0.30
0.05
0.10
44
Hydraulic Flow
Relationship
Upgradient
Down gradient
Upgradient
Down gradient
Upgradient
Down gradient
Upgradient
Down gradient
Upgradient
Down gradient
Upgradient
Down gradient
Upgradient
Down gradient
Upgradient
Down gradient
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Number of
Analyses
2
77
2
77
2
77
1
1
2
77
2
77
2
77
2
77
Number of
Analyses
Exceeding
Standard
27
48
1
18
2
76
1
53
57
Percent
Exceeding
Standard
35
62
50
23
100
98
50
69
77
Maximum
Value
Obtained
(mg/1) I/
2200
14.0
1.14
2.05
0.74
9.60
0.16
0.44
3600
4-127
-------
TABLE 2 Page 2 of 2
Site Name: Shiprock (New Mexico)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 10/16/84 to 09/20/86
Number of
Constituent
pH 3/
Sulfate
Sulfide
Total Solids
Uranium 4/
Zinc
Standard Hydraulic Flow
(mg/1) I/ Relationship
6.5 to 8.5
250
0.05
500
0.044
5.0
Upgradient
Down gradient
Upgradient
Down gradient
Upgradient
Down gradient
Upgradient
Down gradient
Upgradient
Down gradient
Upgradient
Down gradient
Formation of
Completion
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Maximum
Analyses Percent Value
Number of Exceeding Exceeding Obtained
Analyses Standard Standard (mg/1) I/
2
77
2
77
1
23
2
77
1
71
2
77
I/ Values are reported in mg/1 unless otherwise indicated.
2/ Concentrations of nitrate as nitrogen at a level of 10 mg/1 is equivalent to
level of 44 mg/1. All analyses are reported in terms of nitrate as nitrate.
3/ pH reported in standard units.
4/ 30 pci/l of uranium is equivalent of 0.044 mg/1, assuming the bulk of uranium
total uranium in mg/1.
Standard not exceeded.
77
1
23
1
77
55
—
100 19,
100
200
50
100 32,
77
concentration of nitrate
is U-238. All analyses
200
0.10
0.10
534
600
7.21
___
as nitrate at a
are reported as
4-128
-------
4.13 TUBA CITY, ARIZONA - SUMMARY OF WATER QUALITY
The Tuba City site is located in northeastern Arizona about
five miles east of Tuba City. The site rests on the Navajo
Sandstone which contains the primary water source in the
area. Background monitor wells reveal good water quality
(TDS < 500 mg/1) with minor exceptions. The tailings pile
has contaminated approximately one billion gallons of
groundwater.
Cadmium concentrations were higher in on-site and down
gradient samples than in background or upgradient samples.
Seven of 48 down gradient analyses for chromium and four of
13 upgradient analyses for radium exceeded the limit for the
standard. Maximum selenium concentrations exceeded the
standard by a factor of 6. One of 4 on-site samples for
gross alpha, as well as one of 14 down gradient samples,
exceed the standard for gross alpha.
Groundwater flow and at least partial discharge of contami-
nated water is into the Moenkopi Wash, about 2 miles from
the edge of the tailing pile. Modeling shows discharge of
the trailing edge of the mobile contaminant plume to Moen-
kopi Wash in 300 years. Discharge of the uranium plume was
not modeled but is estimated to be several hundred years
after the mobile plume.
4-129
-------
TABLE 1
Site Name: Tuba City (Arizona)
Data Evaluation: Site Water Quality Compared to U.S.
Data Interval: 06/09/82 to 04/11/86
Page 1 of 3
EPA Standards from 40 CFR 192.32(a)
Constituent
Arsenic
Barium
Cadmium
Chromium
Standard Hydraulic Flow
(mg/1) I/ Relationship
0.05 Background
Upgradient
On-Site
Down gradient
1 . 0 Background
Upgradient
On-Site
Down gradient
0.01 Background
Upgradient
On-Site
Down gradient
0 . 05 Background
Upgradient
On-Site
Down gradient
Formation of Number of
Completion Analyses
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
6
13
6
20
6
13
6
20
10
18
6
48
10
18
6
48
Number of Maximum
Analyses Percent Value
Exceeding Exceeding Obtained
Standard Standard (ng/1) !/
4 66 0.031
10 20 0.039
7 14 0.08
4-130
-------
TABLE 1
Site Name: Tuba City (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 06/09/82 to 04/11/86
Page 2 of 3
Constituent
Gross Alpha
(excluding radon
and uranium)
Lead
Mercury
Ra-226 + Ra-228
(Radium)
Selenium
Standard Hydraulic Flow
(mg/1) I/ Relationship
15.0 pCi/1 Background
Upgradient
On-Site
Down gradient
0 . 05 Background
Upgradient
On-Site
Down gradient
0 . 002 Background
Upgradient
On-Site
Down gradient
5 . 0 pCi/1 Background
Upgradient
On-Site
Down gradient
0.01 Background
Upgradient
On-Site
Down gradient
Formation of Number of
Completion Analyses
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
4
9
4
14
6
13
6
20
6
13
6
20
6
13
6
20
10
18
6
48
Number of
Analyses
Exceeding
Standard
___
1
1
___
1
___
1
___
4
— — —
1
6
10
Percent
Exceeding
Standard
...
25
7
_ —
5
___
5
— -
30
— — —
10
100
20
Maximum
Value
Obtained
(mg/1) I/
___
33.2
27.2
___
0.06
___
—
0.0029
___
7.0
— — —
0.018
0.039
0.066
4-131
-------
TABLE 1
Site Name: Tuba City (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards from 40 CFR 192.32(a)
Data Interval: 06/09/82 to 04/11/86
Page 3 of 3
Constituent
Silver
Standard
(mg/1) I/
0.05
Hydraulic Flow
Relationship
Background
Upgradient
On-Site
Down gradient
Formation of Number of
Completion Analyses
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
8
13
6
33
Number of
Analyses
Exceeding
Standard
1
Percent
Exceeding
Standard
12
Maximum
Value
Obtained
(mg/1) I/
0.10
I/ Values are reported in mg/1 unless otherwise indicated.
Standard not exceeded.
4-132
-------
TABLE 2
Site Name: Tuba City (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 06/09/82 to 04/11/86
Page 1 of 4
Standard Hydraulic Flow
Constituent (mg/1) I/ Relationship
Chloride 250
Copper 1 . 0
Fluoride 1.4
Hydrogen Sulfide 0.05
Background
Upgradient
On-Site
Down gradient
Background
Upgradient
on-site
Down gradient
Background
Upgradient
On-Site
Down gradient
Background
Upgradient
On-Site
Down gradient
Number of Maximum
Analyses Percent Value
Formation of Number of Exceeding Exceeding Obtained
Completion Analyses Standard Standard (mg/1) I/
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
10
17
6
48
8
13
6
33
6
12 2 16 4.60
6
20
1
1
1
1
4-133
-------
TABLE 2
Site Name: Tuba City (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 06/09/82 to 04/11/86
Page 2 of 4
Constituent
Iron
Manganese
Molybdenum
Nitrate 2/
Standard Hydraulic Flow
(mg/1) I/ Relationship
0.30 Background
Upgradient
On-Site
Down gradient
0.05 Background
Upgradient
On-Site
Down gradient
0.10 Background
Upgradient
On-Site
Down gradient
44 Background
Upgradient
On-Site
Down gradient
Formation of Number of
Completion Analyses
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
8
13
6
33
8
9
6
33
8
18
6
48
10
17
6
48
Number of
Analyses
Exceeding
Standard
— _
3
3
1
___
1
6
11
3
5
1
28
___
6
24
Percent
Exceeding
Standard
___
23
50
3
___
11
100
33
38
27
17
58
___
100
50
Maximum
Value
Obtained
(mg/1) I/
2.25
1.14
1.96
___
0.10
2.40
0.35
0.21
0.20
0.21
0.24
___
1800
1500
4-134
-------
TABLE 2
Site Name: Tuba City (Arizona)
Data Evaluation: Site Hater Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 06/09/82 to 04/11/86
Page 3 of 4
Constituent
PH 3/
Sulfate
Sulfide
Total Solids
Standard Hydraulic Flow
(mg/1) I/ Relationship
6.5 to 8.5 Background
Upgradient
On-Site
Down gradient
250 Background
Upgradient
On-Site
Down gradient
0.05 Background
Upgradient
On-Site
Down gradient
500 Background
Upgradient
On-Site
Down gradient
Formation of Number of
Completion Analyses
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
Navajo Sandstone
10
18
6
48
10
17
6
48
4
8
4
17
10
13
6
48
Number of
Analyses
Exceeding
Standard
7
1
4
25
_ —
6
20
4
8
4
17
___
1
6
29
Percent
Exceeding
Standard
70
5
66
52
- —
100
41
100
100
100
100
7
100
60
Maximum
Value
Obtained
(mg/1) I/
10.10
8.79
6.19
6.33/12.75
___
2600
4010
0.10
0.10
0.10
0.10
600
7000
8550
4-135
-------
TABLE 2
Site Name: Tuba City (Arizona)
Data Evaluation: Site Water Quality Compared to U.S. EPA Standards Not Included in 40 CFR 192.32(a)
plus Uranium and Molybdenum
Data Interval: 06/09/82 to 04/11/86
Page 4 of 4
Constituent
Uranium 4/
Standard
(mg/1) I/
0.044
Hydraulic Flow
Relationship
Background
Upgradient
On-Site
Down gradient
Formation of Number of
Completion Analyses
Navajo Sandstone 8
Navajo Sandstone 17
Navajo Sandstone 4
Navajo Sandstone 45
Number of
Analyses
Exceeding
Standard
4
19
Percent
Exceeding
Standard
100
42
Maximum
Value
Obtained
(mg/1) I/
2.40
0.21
Zinc
5.0
Background
Upgradient
On-Site
Down gradient
Navajo Sandstone 8
Navajo Sandstone 9
Navajo Sandstone 6
Navajo Sandstone 33
I/ Values are reported in mg/1 unless otherwise indicated.
2/ Concentrations of nitrate as nitrogen at a level of 10 mg/1 is equivalent to concentration of nitrate as nitrate at a
level of 44 mg/1. All analyses are reported in terms of nitrate as nitrate.
3/ pH reported in standard units.
4/ 30 pCi/1 of uranium is equivalent of 0.044 mg/1, assuming the bulk of uranium is U-238. All analyses are reported as
total uranium in mg/1.
Standard not exceeded.
4-136
-------
JUN 17
4.14 Current Uses of Contaminated Ground Water
4.14.1 Drinking Water
Contaminated ground water is believed to be used as
drinking water at only two sites: Gunnison, Colorado, and
Monument Valley, Arizona (Le87). However, because of the
remoteness of some sites it is possible that sporatic use of
contaminated ground water can occur, especially by individuals
or families.
Concentrations of hazardous constituents and other data in
ground water samples from downgradient wells at Gunnison are in
Table 4-1. These same data for upgradient wells are given in
Table 4-2 and for crossgradient wells in Table 4-3. The
locations of these wells are shown in Figures 4-1 and 4-2.
This information is from the draft environmental assessment for
the Gunnison site (DOE84).
In Table 4-1, the downgradient domestic wells are
identified by names (Hitt, Trainer, Rider, Tomichi, Collins,
David, Deschene, Coleman, Corral, Maries, and Valco). Of these
domestic wells, five of 19 samples of ground water exceeded an
uranium concentration of 30 pCi/1 (0.044mg/l) and one of 19
samples exceeded a selenium concentration of 0.01 mg/1. For all
downgradient wells, uranium exceeded 30 pCi/1 in 25 of 59
samples and selenium exceeded 0.01 mg/1 in nine of 73 samples.
In addition, for other hazardous constituents, cadmium
concentrations exceeded 0.01 mg/1 in four of 58 samples and
nitrate concentrations exceeded 10 mg/1 in seven of 59 samples.
In Tables 4-2 and 4-3, only three samples of ground water
exceeded the drinking water standards for hazardous
constituents. These three samples contained nitrate at
concentrations of 22 to 35 mg/1 and were collected immediately
upgradient of the tailings pile.
The Gunnison ground water data indicate that uranium and
sulfate have moved from the tailings area since peak
concentrations are found downgradient from the tailings
(DOE86). It is reasonable to suspect, therefore, that
concentrations of uranium and sulfate will increase in the
downgradient domestic wells as these contaminants move
downgradient. Figure 4-3 depicts the uranium plume near the
Gunnison pile.
4-137
-------
Table 4-1 Ground-water quality - fiunntson - doMgradttnt
Hell
203A
2038
2048
205A
2058
206A
2068
207A
2078
208
209A
2098
210A
2108
211A
2118
21 2A
2128
c
Date
10/24/83
10/25/83
10/27/83
10/23/83
10/24/83
10/19/83
01/31/84
01/31/84
10/19/82
02/01/84
02/01/84
10/17/83
01/29/84
10/17/83
01/29/84
10/12/83
10/13/83
10/13/83
10/14/83
10/17/83
01/29/84
10/17/83
01/29/84
10/23/84
10/20/83
10/25/83
10/26/83
10/18/83
01/26/84
10/18/83
01/27/84
Electrical
onductlvlty
(iMtlO/C*)
580
400
1450
1040
310
1710
N/A
N/A
1800
N/A
N/A
1280
N/A
1920
N/A
1435
1340
1300
1300
1620
N/A
2050
N/A
1620
1940
1900
1670
1510
N/A
2100
N/A
<•«'
11.5
14
14.5
13
14
11
8.8
8.8
13.0
7.0
7.0
12.0
8.2
11
8.0
11.0
10.0
11.5
11.0
11
8.4
12
8.0
12
16
12
14
10
9.0
13.0
7.1
PH
.42
.88
.19
.13
.95
.55
.30
.30
.11
N/A
N/A
5.88
6.06
5.76
6.31
4.74
4.75
5.11
5.08
6.38
6.95
6.15
6.29
5.97
6.28
5.89
6.53
5.49
6.12
6.08
6.48
Mkallnltj
(as CaC03
282
264
188
182
240
145
110
N/A
382
290
N/A
195
95
195
170
65
75
58
56
195
115
285
220
314
360
188
344
135
100
345
280
1 A1
<0.002
<0.002
0.190
<0.002
<0.002
0.157
0.028
<0.10
<0.003
0.054
<0.10
<0.003
0.010
0.013
0.042
0.119
0.111
0.106
0.113
<0.003
0.014
0.014
0.038
<0.003
<0.003
0.135
<0.02
<0.003
0.019
<0.003
0.030
As Ba
<0.001 0.029
<0.001 0.024
0.002 0.043
<0.001 0.019
<0.001 0.169
0.004 0.057
<0.001 0.005
<0.010 <0.010
<0.001 0.090
<0.001 0.006
<0.010 <0.10
<0.001 0.016
<0.001 0.006
<0.001 0.040
<0.001 0.009
<0.001 <0.002
<0.001 <0.002
<0.001 <0.002
<0.001 <0.002
<0.001 0.026
<0.001 0.012
<0.001 0.075
<0.001 0.013
<0.001 <0.002
<0.001 0.026
0.003 0.026
<0.001 0.029
<0.001 0.023
<0.001 0.028
<0.001 0.115
<0.001 0.009
Ca
121.
75.0
568.
51.5
61.0
467.
486.
460.
640.
556.
580.
232.
231.
573.
589
335
321
324
331
322
413
599
523
459
603
457
540
349
293
613
483
Cd
<0.0005
<0.0005
<0.0005
0.0111
<0.0005
0.034
<0.0001
<0.001
0.010
<0.0001
<0.001
0.007
<0.0001
0.017
<0.0001
<0.0005
<0.0005
<0.0005
<0.0005
0.008
<0.0001
0.008
<0.0001
0.005
0.007
<0.0005
-------
Table 4-1 Ground-water quality - Gunntson - domgradlmt (Continued)
Well
203A
2038
2048
205A
2058
206A
206B
207A
207B
208
209A
2098
210A
2108
21 1A
21 IB
21 2A
21 2B
Date
10/24/83
10/25/83
10/27/83
10/23/83
10/24/83
10/19/83
01/31/84
01/31/84
10/19/82
02/01/84
02/01/84
10/17/83
01/29/84
10/17/83
01/29/84
10/12/83
10/13/83
10/13/83
10/14/83
10/17/83
01/29/84
10/17/83
01/29/84
10/23/84
10/20/83
10/2S/83
10/26/83
10/18/83
01/26/84
10/18/83
01/27/84
Hg
26.4
14.6
23.1
61.2
11.8
86.1
75.5
72.0
42.1
36.5
36
64.4
58.0
30.5
28.2
38.4
37.5
37.0
38.1
91.7
96.8
35. 0
33.0
78.2
46.8
112
46.2
78.5
66.3
42.6
30.5
Nn
N/A
N/A
N/A
N/A
N/A
N/A
66.5
77.0
N/A
9.40
9.40
N/A
24.4
N/A
3.36
N/A
N/A
N/A
N/A
N/A
35.5
N/A
4.93
N/A
N/A
N/A
N/A
N/A
38.0
N/A
5.00
No
<0.001
<0.001
0.058
0.003
0.009
0.008
<0.001
<0.01
0.007
<0.001
<0.010
<0.001
<0.001
0.008
<0.001
<0.001
<0.001
<0.001
<0.001
0.003
<0.001
0.008
<0.001
0.002
0.006
<0.001
0.006
0.002
<0.001
0.007
<0.001
N03
45
50
3.5
11.0
4.8
2.3
3.1
< 1
< 0.7
2.0
< 1.0
1.0
2.4
1.1
2.6
< 0.7
1.1
1.0
< 0.7
1.0
2.3
< 0.7
2.1
110
2.3
45
12
1.4
2.3
<0.7
2.3
Na
41.6
34.8
65.5
88.7
33.2
109
49.9
45
48.6
21.8
18.0
94.4
47.5
43.9
16.6
53.4
53.2
50.1
54.2
96.5
100
44.2
19.3
183
45.1
128
58.0
92.0
54.3
46.6
25.3
Nt
<0.001
<0.001
0.002
0.061
0.019
0.015
<0.04
<0.04
0.045
<0.04
0.14
0.002
<0.04
0.068
<0.04
0.13
0.13
0.20
0.18
0.002
<0.04
0.049
<0.04
<0.001
0.051
<0.001
0.018
<0.001
<0.004
0.020
<0.004
P
N/A
N/A
N/A
N/A
N/A
N/A
< 5
N/A
N/A
< 5
N/A
N/A
< 5
N/A
< 5
N/A
N/A
N/A
N/A
N/A
< 5
N/A
< 5
N/A
N/A
N/A
N/A
N/A
< 5
N/A
< 5
Pb
0.009
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
0.010
0.001
<0.001
<0.010
0.002
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
co.ooi
0.010
<0.001
<0.001
<0.001
0.009
<0.001
<0.001
<0.001
<0.001
<0.001
< 0.001
< 0.001
so4
205
51.0
1480
24.7
22.3
1720
1620
1600
1500
1520
1300
886
845
1620
1500
1100
1100
1100
1100
1140
1600
1520
1430
1640
1S40
1820
1390
1280
1160
1S40
1180
Se
<0.002
<0.002
0.007
0.016
<0.002
0.036
<0.002
<0.005
0.030
<0.002
<0.005
<0.002
<0.002
0.005
<0.002
0.100
0.087
0.085
0.085
0.006
<0.002
0.004
<0.002
0.002
<0.002
0.008
0.006
0.012
<0.002
0.003
<0.002
SI
1.7
3.8
N/A
N/A
N/A
N/A
7.5
20
N/A
2.6
N/A
N/A
7.5
N/A
5.4
0.8
0.7
1.2
6.4
N/A
10.0
N/A
12.6
1.9
N/A
1.6
5.6
N/A
6.8
N/A
6.2
U
0.0181
0.0184
0.116
0.0018
0.0033
0.0048
0.0028
0.005
0.917
1.07
1.086
0.0052
0.0033
0.801
0.986
0.275
0.0421
0.0265
0.0353
0.0110
0.0049
1.02
0.909
0.200
0.863
0.0078
0.622
0.0061
0.0044
1.24
1.03
V
<0.004
<0.004
<0.004
<0.004
<0.004
0.006
<0.004
<0.01
0.007
<0.004
<0.01
<0.004
<0.004
<0.004
<0.004
0.046
0.047
0.046
0.004
0.009
<0.004
0.005
<0.004
<0.004
0.11
<0.004
<0.004
<0.004
<0.004
<0.004
<0.004
Zn
0.005
0.003
0.289
0.012
0.009
0.045
0.021
0.04
0.320
0.502
0.57
0.014
0.012
1.46
1.27
0.106
0.093
0.098
0.0094
0.013
0.015
0.746
0.721
0.054
0.390
0.009
0.021
0.032
0.016
0.016
0.115
Pb-210
(pCI/1)
0.6 * 3.1
0.3+1.7
1.672.2
11 ? 1.0
3.9? 1.0
2.3 ? 3.6
0.0 7 1.6
-------
Table 4-1 Ground-water quality - Gunnlson - dowigradlent (Continued)
Mell
21 3A
2138
2148
Hltt
Trainer
Rider
ToMtchl
Collins
David
Deschene
Colenan
Corral
Narks
Vako
Nlllslte
SP-1
SP-3
CSU-213
CSU-214
Electrical
conductivity
Date (uriio/cn)
10/18/83
10/18/83
10/26/83
02/02/84
02/07/84
02/27/84
01/30/84
01/30/84
09/16/83
09/16/83
11/01/82
10/11/82
09/16/83
10/11/82
09/15/83
02/07/84
09/16/83
10/07/83
02/01/84
02/01/84
10/11/82
09/16/83
11/01/82
09/16/83
10/12/82
11/01/82
11/01/82
11/01/82
1510
1100
500
N/A
N/A
N/A
N/A
N/A
385
395
510
350
305
390
540
N/A
340
610
N/A
N/A
400
460
345
780
400
600
1950
290
Te«p.
CO
11.5
N/A
14
14
6.4
9.7
4.3
4.3
13
9.0
13
11
11.0
12
11
e.e
12
12
5.7
5.7
12
10.4
12
8
16
9
9
12
Alkalinity
pH (as CaC03) A1 As Ba Ca
6.31
6.77
7.24
N/A
7.0
7.2
7.17
7.17
6.25
6.27
7.48
7.41
6.54
8.00
6.50
7.25
6.72
6.80
N/A
N/A
7.49
6.5
7.63
7.11
7.58
7.65
7.10
7.4
2456
245
308
240
260
100
250
N/A
280
199
290
N/A
200
199
230
205
250
260
210
N/A
209
260
190
250
N/A
N/A
N/A
N/A
<0.003 <0.001 0.047 364
<0.003 <0.001 0.118 247
0.015 <0.001 0.228 129
0.004 <0.001 0.009 79.2
0.002 <0.001 0.007 129
0.003 <0.001 0.002 31.0
0.007 <0.001 0.009 86.6
<0.10 <0.010 0.13 93
0.159 <0.001 0.069 33.3
0.152 <0.001 0.026 101
-------
Table 4-1 Ground-Mater quality - Gunntson - downgradlent (Continued)
Hell
21 3A
21 3B
214B
Hltt
Trainer
Rider
Tofttcht
Collins
David
Deschene
Col nan
Corral
Harks
Valco
Hills* te
SP-1
SP-3
CSU-213
CSU-214
Date
10/18/83
10/18/83
10/26/83
02/02/84
02/07/84
02/27/84
01/30/84
01/30/84
09/16/83
09/16/83
11/01/82
10/11/82
09/16/83
10/11/82
09/15/83
02/07/84
09/16/83
10/07/83
02/01/84
02/01/84
10/11/82
09/16/83
11/01/82
09/16/83
10/12/82
11/01/82
11/01/82
11/01/82
Kg
61.2
28.2
18.3
20.1
27.5
6.48
20.4
20
3.1
9.50
10.0
<1
15.6
16
22.2
14.4
15.3
21.9
22.2
19
18
19.6
17
16.8
16
16
43
11
Hn
N/A
N/A
N/A
2.05
0.06
0.03
0.08
0.07
N/A
N/A
N/A
N/A
N/A
N/A
N/A
0.43
N/A
N/A
0.24
0.18
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
No
0.004
<0.001
0.007
<0.001
<0.001
<0.001
<0.001
<0.01
<0.001
<0.001
<0.05
<0.05
<0.001
<0.05
<0.001
<0.001
<0.001
<0.001
<0.001
<0.01
<0.05
<0.001
<0.05
<0.001
<0.05
<0.05
<0.05
<0.05
N03
<0.7
1.0
2.3
2.7
<0.7
<0.7
2.5
<1
<0.7
<0.7
<5
<5
1.5
<5
1.3
1.8
1.3
1.1
2.4
<1
<5
1.7
<5
1.3
<5
<5
115
<5
Na
75.7
36.0
38.7
13.9
8.13
3.81
10.1
6.5
94.1
25.1
9.0
122
20.5
10
23.4
4.88
17.2
12.9
12.0
6.6
10
19.5
7
16.9
7
11
22
4
Nl
<0.001
<0.001
0.008
<0.004
<0.04
<0.04
<0.04
<0.04
0.053
0.053
N/A
N/A
0.052
N/A
0.072
<0.04
0.042
0.06
<0.04
<0.04
N/A
0.070
N/A
0.064
N/A
N/A
N/A
N/A
P
N/A
N/A
N/A
< 5
< 5
< 5
< 5
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
< 5
N/A
< 5
< 5
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Pb
0.007
<0.001
<0.001
<0.001
<0.001
<0.001
<0.0012
<0.010
<0.001
<0.001
<0.010
<0.010
<0.001
<0.010
<0.001
<0.001
<0.001
<0.001
<0.001
<0.010
<0.010
<0.001
<0.010
<0.001
<0.010
<0.010
<0.010
N/A
so4
1000
504
162
66.3
191
14.8
74.9
73
117
16.1
135
51
61.2
44
170
58.0
46.3
< 1
139
140
29
50.5
22
24.9
44
260
1647
15
Se
0.008
<0.002
<0.002
<0.002
<0.002
<0.002
<0.002
<0.005
<0.002
<0.002
<0.010
<0.010
<0.002
<0.010
<0.002
<0.002
<0.002
0.02
<0.002
<0.005
<0.010
<0.002
<0.010
<0.002
<0.010
<0.010
<0.010
<0.010
SI
N/A
N/A
1.8
1.6
1.3
1.4
6.2
7
N/A
N/A
5.2
5.6
N/A
6.7
N/A
2.4
N/A
0.5
1.4
6
7.4
N/A
7.1
N/A
6.6
5.0
9.7
N/A
U
0.262
0.259
0.656
0.0046
0.0243
0.0013
0.0096
0.011
0.0030
0.0493
0.068
0.030
0.0424
0.060
0.0583
0.0385
0.0092
0.198
0.0161
0.018
0.012
0.0166
0.006
0.0032
0.044
0.148
1.00
0.028
V
0.007
<0.004
<0.004
<0.004
<0.004
<0.004
<0.004
<0.01
<0.004
<0.004
<0.05
<0.05
<0.004
<0.005
<0.004
<0.004
<0.004
<0.004
<0.004
<0.01
<0.05
<0.004
<0.05
<0.004
-------
Table 4-1 Ground-water quality - Gunntson - dowigradtent (Continued)
Hell
Sf-1
SP-2
SJ»-3
GUN -209
6UN-212A
GUN -213
GUN-214
Electrical
conductivity
Date (iMho/ca)
08/31/82
06/30/82
11/00/81
08/31/82
06/30/82
11/00/81
08/31/82
06/30/82
11/00/81
08/31/82
06/30/82
11/00/81
08/31/82
06/30/82
08/31/82
06/30/82
11/00/81
08/31/82
06/30/82
440
N/A
N/A
1960
N/A
N/A
110
N/A
N/A
2100
N/A
N/A
2010
N/A
2190
N/A
N/A
400
N/A
Te*>.
CO
14
N/A
N/A
14
N/A
N/A
14
N/A
N/A
15
N/A
N/A
IS
N/A
15
N/A
N/A
16
N/A
Alkalinity
pH (as CaC03)
6.91
7.30
N/A
3.65
3.82
N/A
6.58
6.49
N/A
6.65
6.68
N/A
5.85
6.59
6.24
6.54
N/A
6.53
6.90
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
A)
<0.1
0.1
<0.1
132.0
71.0
78.0
<0.1
0.2
<0.1
0.2
0.9
«U
0.3
0.6
0.3
0.3
0.2
0.2
0.2
As
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Ba
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Ca
82
84
86
495
461
249
248
190
253
588
434
462
600
434
632
563
597
76
93
Cd
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Cl
3
4
3
6
4
<2
5
15
2
6
12
5
4
12
4
13
54
<2
11
Cr
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Cu
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
F
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Fe
0.03
0.012
0.02
14.9
4.60
7.30
0.36
0.08
0.10
0.16
1.59
<0.01
21.4
11.6
22.4
0.67
0.30
0.05
0.46
K
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
[•/A - Not Analyzed]
4-142
-------
Table 4-1 Ground-water quality - Gunnison - dowigradtent (Continued)
Well
SP-1
SP-2
SP-3
GUN -209
6UH-212A
GUN -213
GUN -214
Date
08/31/82
06/30/82
11/00/81
08/31/82
06/30/82
11/00/81
08/31/82
06/30/82
11/00/81
08/31/82
06/30/82
11/00/81
08/31/82
06/30/82
08/31/82
06/30/82
11/00/81
08/31/82
06/30/82
Mg
16
17
17
82
60
36
21
22
28
47
40
52
46
48
39
44
SO
12
12
Mn
0.4
0.03
N/A
8.63
6.20
N/A
.25
0.05
N/A
.43
0.74
N/A
8.79
9.30
8.16
5.20
N/A
0.03
0.11
No
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N03
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Na
.6
6
6
32
17
9
9
22
10
22
22
39
31
34
4
24
26
4
5
Nl
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
P
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Pb
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
so4
14
34
77
780
757
1150
140
125
562
480
422
1150
560
560
480
571
1440
16
43
Se
<0.1
70.1
N/A
0.1
0.4
N/A
<0.1
70.1
N/A
<0.1
~0.1
N/A
0.1
0.1
0.1
<0.1
~N/A
«U
70.1
SI
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
U
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
V
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Zn
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Pb-210
(pCt/1)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
[•/A • Not Available
4-143
-------
Table 4-1 Ground-Mater quality - Gunnlson - dotmgradlent (Continued)
Well
203A
203B
2048
205A
2058
206A
2068
207A
2076
208
209A
2098
210A
2108
21 1A
2118
21 2A
2128
Date
10/24/83
10/25/83
10/27/83
10/23/83
10/24/83
10/19/83
01/31/84
01/31/84
10/19/82
02/01/84
02/01/84
10/17/83
01/29/84
10/17/83
01/29/84
10/12/83
10/13/83
10/13/83
10/14/83
10/17/83
01/29/84
10/17/83
01/29/84
10/23/84
10/20/83
10/25/83
10/26/83
10/18/83
01/26/84
10/18/83
01/27/84
Ra-226
(PC1/1)
0.0 + 0.6
0.0 + 0.2
0.9 + 0.6
0.4 + 0.4
0.1 + 0.2
0.7 + 1.0
0.0 + 0.2
<~1
0.1 + 0.3
0.1 + 0.2
<~1.0
0.1 + 0.1
0.0 + 0.2
0.1 + 0.2
0.1 + 0.2
0.0 + 0.2
0.0 + 0.2
0.0 + 0.2
0.1 +0.2
0.2 + 0.2
0.0 + 0.2
0.4 + 0.3
0.0 + 0.2
0.0 + 0.6
0.0 + 0.3
0.0 + 0.2
0.4 + 0.5
0.1 +0.1
0.0 + 0.2
0.2 + 0.2
0.0 + 0.2
Th-230
(pCI/1)
0.0 + 1.9
0.6 + 0.7
8.6 + 2.6
1.2 + 1.8
0.0 + 0.8
0.4 + 1.4
0.0 + 0.4
<~0.1
2.8 + 2.4
0.6 + 0.7
<~0.3
2.7 + 2.2
0.4 + 0.6
0.8 + 1.6
0.6 + 0.7
0.0 + 0.5
0.0 + 0.5
0.0 + 0.5
0.0 + 0.5
0.4 + 1.4
0.7 + 0.9
3.6 + 2.6
0.0 + 0.4
2.0+2.1
3.2 + 2.5
0.4 + 0.6
0.6 + 2.0
0.4 + 1.4
0.4 + 0.6
1.2 + 1.8
0.3 + 0.6
TDS
624
347
2280
1340
256
2670
2740
2700
2720
2550
2500
1420
1410
2420
2440
1720
1690
1700
1730
1870
2570
2120
2400
2760
2610
3160
2250
1940
1900
1720
2270
4-144
-------
Table 4-1 Ground-Mater quality - Gunntson - downgradlent (Concluded)
Hell
21 3A
21 38
214B
Hltt
Trainer
tilder
Tomichl
Collins
David
Oeschene
Coleman
Corral
Harks
Valco
Mill site
SP-1
SP-3
CSU-213
CSU-214
Date
10/18/83
10/18/83
10/26/83
02/02/84
02/07/84
02/27/84
01/30/84
01/30/84
09/16/83
09/16/83
11/01/82
10/11/82
09/16/83
10/11/82
09/15/83
02/07/84
09/16/83
10/07/83
02/01/84
02/01/84
10/11/82
09/16/83
11/01/82
09/16/83
10/12/82
11/01/82
11/01/82
11/01/82
Ra-226
(pCI/1)
0.2 + 0.2
0.2 + 0.2
0.2 +0.2
0.0 + 0.2
0.0 + 0.2
0.0 + 0.2
0.0 + 0.2
0
0.1 + 0.2
0.2 + 0.3
<~2
< 2
0.5 + 0.4
<~2
0.0 + 0.2
0.2 +0.3
0.1 +0.2
0.3 + 0.3
0.0 + 0.2
71
< 2
0.0 + 0.2
?2
0.0 + 0.2
?2
< 2
< 2
< 2
Th-230
(PCI/1)
0.4 + 1.4
0.0 + 1.5
1.2 +2.3
0.0 + 0.4
0.0 + 0.4
0.0 + 0.4
0.1 + 0.5
<~0.1
0.2 + 0.7
0.8 + 1.0
N/A
N/A
0.8 + 1.0
N/A
0.8 + 0.9
0.0 + 0.4
1.2 +1.0
0.9 + 1.1
0.2 + 0.5
<~0.1
N/A
1.0 + 0.9
N/A
0.7 + 0.8
N/A
N/A
N/A
N/A
TOS
994
2670
459
370
556
119
401
N/A
277
372
N/A
N/A
302
N/A
481
304
288
500
450
400
N/A
351
N/A
296
N/A
N/A
N/A
N/A
All measurements as mg/1 unless otherwise stated
N/A = Not analyzed.
4-145
-------
Table 4-2 Ground-water quality - Gunnlson - upgradtent
Well
201 A
201B
202k
202B
Weaver
Cooper
Brat ton
City
City 19
Hoods
Singer
Electrical
conductivity leap.
Date (urfio/oO CO
10/23/83
10/21/83
10/19/83
10/21/83
02/07/84
02/06/84
07/27/84
11/01/82
09/15/83
02/27/84
11/01/82
09/16/83
11/01/82
09/16/83
330
380
350
375
N/A
N/A
N/A
315
355
N/A
280
310
330
350
12
14.5
11.5
14
8.3
7.5
7.0
12
12.0
6.9
15
14.8
14
12
Alkalinity
pH (as CaC03) Al
7.57
7.11
7.0
7.1
7.45
7.2
7.4
7.55
6.5
7.4
7.26
6.68
7.86
6.62
216
254
240
245
215
130
300
N/A
240
220
N/A
200
N/A
290
<0.002
<0.003
<0.003
<0.003
0.003
0.005
0.006
<0.10
0.147
0.002
<0.10
0.143
<0.10
0.150
As
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
<0.010
<0.001
<0.001
<0.010
<0.001
<0.010
<0.001
Ba
0.021
0.028
0.070
0.120
0.005
0.005
0.002
N/A
0.270
0.002
N/A
0.233
0.18
0.275
Ca
58.0
69.5
85.0
84.9
59.8
35.3
70.3
76
70.8
64.3
55
61.0
70
76.3
Cd
<0.0005
0.005
0.008
0.006
<0.0001
<0.0001
<0.0001
<0.005
<0.001
<0.0001
N/A
<0.001
N/A
<0.001
Cl
8.0
9.4
12
11
7.8
14
12.6
2
3.0
5.5
2
4.8
1
5.0
Cr
<0.001
0.003
<0.001
<0.001
<0.001
<0.001
<0.001
<0.010
<0.001
<0.001
N/A
<0.001
N/A
<0.001
Cu F
0.006 <0.1
<0.001 <0.1
<0.001 <0.1
<0.001 <0.1
<0.001 <0.1
<0.001 <0.1
<0.001 <0.1
0.013 <1
<0.001 N/A
<0.001 <0.1
N/A <1
0.046 N/A
N/A <1
<0.001 N/A
Fe
0.011
0.02
0.27
2.80
0.17
0.38
0.05
0.6
0.263
0.11
2.7
0.254
3.3
0.277
H*
N/A
N/A
N/A
N/A
N/A
N/A
N/A
<0.002
N/A
N/A
N/A
N/A
N/A
N/A
K
5.25
3.69
1.85
3.38
1.30
2.38
14.0'
4
5.05
1.38
3
7.33
1
7.25
[N/A - Not Analyzed
4-146
-------
Table 4.2 Ground-water quality - Gunntson - upgradlent (Continued)
Hell
201A
201B
202A
202B
Heaver
Cooper
Bratton
City
City 19
Hoods
Singer
Date
10/23/83
10/21/83
10/19/83
10/21/83
02/07/84
02/06/84
07/27/84
11/01/82
09/15/83
02/27/84
11/01/82
09/16/83
11/01/82
09/16/83
NO
12.5
13.9
16.8
15.8
13.8
10.3
26.3
14
14.1
13.0
12
14.3
14
15.0
Nn
N/A
N/A
N/A
N/A
N/A
0.23
0.02
N/A
N/A
0.03
N/A
N/A
N/A
N/A
No
0.004
<0.001
0.003
0.003
<0.001
<0.001
<0.001
<0.05
<0.001
<0.001
<0.05
<0.001
<0.05
<0.001
N03
35
25
22
3.1
2.0
1.9
1.7
< 5
1.1
< 0.7
< 5
< 0.7
< 5
1.5
Na
39.4
9.22
6.87
7.49
6.78
14.9
19.3
6
15.8
3.83
6
18.1
5
16.2
Nt
0.003
<0.001
<0.001
<0.001
<0.04
<0.04
<0.04
N/A
0.071
<0.04
N/A
0.037
N/A
0.043
P
N/A
N/A
N/A
N/A
< 5
< 5
< 5
N/A
N/A
< 5
N/A
N/A
N/A
N/A
Pb
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
<0.010
<0.001
<0.001
N/A
<0.001
N/A
0.012
»,
24.7
49.5
31.2
28.1
9.9
16.1
36.2
15
43.8
16.5
11
11.4
15
19.5
Se
<0.002
<0.002
<0.002
<0.002
<0.002
<0.002
< 0.002
<0.010
<0.002
<0.002
<0.010
<0.002
<0.010
<0.002
St
5.6
5.1
0.5
5.7
0.6
1.6
5.7
8.2
N/A
1.2
N/A
N/A
N/A
N/A
U
0.0062
0.0038
0.0018
0.0063
0.0020
0.0032
0.0085
0.003
0.0023
0.0021
0.003
0.0078
0.003
0.0039
V
<0.004
<0.004
<0.004
<0.004
<0.004
<0.004
<0.004
<0.05
<0.004
<0.004
<0.05
<0.004
<0.05
<0.004
Zn
0.0|1
0.005
0.014
0.012
0.047
0.065
0.044
N/A
0.017
<0.005
N/A
0.022
N/A
0.023
Pb-210
(pCI/1)
2.0 + 0.8
2.7 +2.6
3.0 + 3.4
1.2 + 2.2
0.0+1.6
0.2+1.6
0.3 + 1.0
N/A
3.3 +2.3
0.5 + 1.1
N/A
3.1 + 2.0
N/A
3.3 + 0.8
[N/A • Not Analyzed]
4-147
-------
Table 4_2 Ground-water quality - Gunnlson - upgradlent (Concluded)
Well
201A
201B
202A
202B
Weaver
Cooper
Bratton
City
City 19
Woods
Singer
Date
10/23/83
10/21/83
10/19/83
10/21/83
02/07/84
02/06/84
07/27/84
11/01/82
09/15/83
02/27/84
11/01/82
09/16/83
11/01/82
09/16/83
Ra-226
(PC1/1)
0.0 + 0.2
0.4 + 0.4
0.1 + 0.2
0.0 + 0.3
0.0 + 0.2
0.0 + 0.2
0.0 + 0.2
< 2
0.8 +_ 0.5
0.0 +0.2
< 2
0.4 +0.4
< 2
0.3 +0.3
Th-230
(PCI/1)
0.0 + 0.8
2.4 + 2.2
0.0 + 1.4
0.8 + 1.6
0.1 +0.5
0.0 + 0.9
0.0 + 0.4
N/A
0.1 +0.7
0.0 + 0.5
N/A
0.0 + 0.6
N/A
0.5 + 0.8
TOS
291
381
345
359
262
199
401
N/A
262
246
N/A
196
N/A
282
N/A » Not analyzed.
4-148
-------
Table 4-3 Ground-Mater quality - Gunntson - crossgradtent
Electrical
conductivity Teap. Eh
Wei 1 Date
Tuttle 11/01/82
10/26/83
Reid 11/01/82
Hatcher 10/06/83
SJoberg 10/06/83
02/08/84
Wallace 10/06/83
02/08/84
(urtio/«) CC) («V)
180
162
180
160
155
N/A
290
N/A
13
13
11
10
10
7
10
6
.5 N/A
162
N/A
N/A
N/A
.2 N/A
N/A
.0 N/A
pH
7.68
7.03
7.60
6.8
6.81
7.17
7.05
7.0
Alkalinity
(as CaC03) Al As Ba
68
118
N/A
145
115
100
230
205
<0.
0.
<0.
-------
Table 4-3 Ground-water quality - Gunnlson - crossgradlent (Concluded)
Well
Tuttle
Reid
Hatcher
Sjoberg
Wallace
Date
11/01/82
10/26/83
11/01/82
10/06/83
10/06/83
02/08/84
10/06/83
02/08/84
Po-210
(pCi/1)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Ra-226
(pCI/1)
< 2
0.3 + 0.3
< 7
0.3 + 0.3
0.0 + 0.2
0.1 +0.2
0.5 +0.3
0.4 + 0.3
Ra-228
(PCi/1)
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Th-230
(PCi/1)
N/A
2.5 + 1.4
N/A
0.2 + 0.9
0.4 + 0.6
0.2 + 0.9
0.8 + 1.1
0.0 + 0.4
TOS
N/A
72.0
N/A
117
112
190
281
246
All measurements as mg/1 unless otherwise stated.
N/A = Not analyzed.
4-150
-------
WEAVER A
CITY +Q&1MI
1/8
SCALE IN MILES
FIGURE 4-1
APPROXIMATE LOCATION OF DOMESTIC WELLS SAMPLED AT QUNNI8ON
4-151
-------
A4B.
•2oa Ate*
LOCATIONS OP MONITOR WELLS
FOR UMTRA INVESTIGATION (GUNNISON)
MOST WELH INSTALLED At PAIRS *» 1O FT APART.
DEPTH OP 'A* Wltt§«4« PT, '•* WELL8«<1§ FT
4-152
-------
-10X = I8OPLETH
tOt Or tllSTINO ^
TAILINGS PILI
TAILINGS
PILE
— IX
FIGURE 4-3
URANIUM PLUME NEAR PILE (GUNNISON)
U AS MULTIPLE OF HIGHEST BACKGROUND CONCENTRATION (0.008 mg/l)
DATA: 83 SAMPLES FROM 48 WELLS
4-153
-------
At the Monument Valley site there are four residences which
may be using ground water as drinking water as shown in Figure
4-4. Ground water quality at these residences is reflected by
concentration levels in sampling wells 602 610, 613, 621, and
622, where chromium and gross alpha exceed drinking water
standards at 622 and 610 respectively as shown in Table 4-4.
Also/ the sulfate concentration is elevated at well 622.
Background water quality is shown in Table 4-5 for the
alluvial aquifer at Monument Valley and in Table 4-6 for the
Shinarump and DeChelly Sandstone aquifers. Figure 4-5
illustrates the sulphate plume at Monument Valley, Figure 4-6
the nitrate plume, and Figure 4-7 the uranium plume. The
locations of the four residences are shown in each figure
4.15 Organic Contaminants in Ground Water
Few data are available regarding organic contaminants in
ground water. The NRC is conducting a program of sampling
liquids in uranium mill tailings impoundments. This program is
to establish a data base for hazardous constituents (40 CFR 261
Appendix VIII) in the tailings (Sm87).
The laboratory analyses performed on these tailings water
samples indicate positively if any of 150 constituents are
present in the tailings solution. These constituents include 54
general chemistry (anions, cations, metals) 12 volatile organic
groups, 81 semivolatile groups, and three radionuclides. None
of the organics have been found in the tailings solutions that
were tested from nine tailings impoundments by the NRC. The
elemental forms of 15 hazardous constituents were identified.
These organic groups and the 15 hazardous constituents that
tested postive are listed in Table 4-7.
In uranium milling uranium has been recovered from leach
liquors by three methods: solvent extraction, ion exchange, and
precipitation. The solvent extraction method was used to
produce 43% of total uranium production in 1976 and a solvent
extraction/ion exchange combination was used to produce 18% the
same year (NUREG-0706) . Two processes, the Dapex and the Amex,
are extensively used. The Dapex process uses a 4% solution of
di (2-ethylhexyl) phosphoric acid (EHPA) in kerosene with
tributyl phosphate added as a modifier. The Amex process uses a
6% solution of tertiary amine, such as alinine-336, in kerosene
with isodecanol added as a modifier.
4-154
-------
N
INDIAN SERVICE
ROUTE 6440
TO MONUMENT
NO. 2 MINE
LEGEND
e 661
• RESIDENCE
9 DOE MONITOR WELL
EPHEMERAL DRAINAGE
TO HALCHITA AND
MEXICAN HAT
«6S2
APPROXIMATE SCALE IN FEET
FIGURE 4-4
DOE MONITOR WELL LOCATIONS,
MONUMENT VALLEY SITE
4-155
-------
Table 4_4 Exceedence of water-quality standards
at Monument Valley
Arsenic
Barium
Cadmium
Chloride
Chromium
Copper
Gross alpha^.c
Iron
Lead
Manganese
Mercury
Nitrate (as N)
pHd
Ra-226 «• 228&
Selenium
Silver
Sulfate
Total dissolved
solids
Uranium6
Z1nc
EPA primary EPA secondary
standard3 standard*
0.05
1.0
0.01
250.0
0.05
1.0
15
0.3
0.05
0.05
0.002
10.0
6.5-8.5
5.0
0.01
0.05
250.0
500.0
0.015
5.0
Exceeded at
none
none
none
none
614, 622
none
606, 610,
657, 662,
614. 610
none
603. 605. 606
620. 621. 622
651. 654. 659
655. 662. 657
none
606, 655.
620. 622. 650
663. 668.
none
none
none
605. 606. 622
655. 656. 662
60S. 606. 614
620, 622.
606. 614. 620
657. 662
none
614.
620.
. 610,
, 650,
, 660,
. 664
656
, 660,
661
, 653.
, 669
, 617.
657
, 655,
aM1ll1grams per liter (mg/1) unless otherwise noted.
&P1cocur1es per liter.
cReported values of gross alpha may be erroneous
500 mg/1.
(^Standard units.
eHealth advisory level (Cothern et al.. 1983).
at TDS levels above
4-156
-------
Table 4_5 Background water quality 1n alluvial aquifer, Monument
Valley site
Constituent
Observed
concentration No. of
range3 analyses
Mean3
Two Background
standard concentration
deviations3 range3
Alkalinity3
Aluminum
Ammonium
Antimony
Arsenic
Barium
Boron
Bromide
Cadmium
Calcium
Chloride
Chromium
Cobalt
Copper
Cyanide
Fluoride
Gross alpha'5
Gross betab
Iron
Lead
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Nitrate
Nitrite
Nitrate & Nitrite
(ss N)
Total organic
carbon
Lead-21Qb
PH
Phosphate
Polon1um-2lOD
Potassium
Rad1um-226b
Rad1um-228b
Selenium
Silica
Silver
Sodium
196-293
0.2-0.8
<0.1-0.52
<0. 003-0. 004
<0.01
<0.1-0.3
0.2-0.8
<0.01
<0.001
18.0-35.5
10.0-27.0
<0. 01-0. 04
<0.05
<0. 02-0. 03
<0.01
0.20-0.90
1.2-7.6
<1;0-20.0
<0. 03-0. 18
<0.01
17.9-31.2
<0. 01-0. 02
<0.0002
<0. 01-0. 11
<0. 04-0. 13
3.0-22.2
<0. 10-0. 99
2.1-5.0
1.3-79.0
<1.5-5.8(*1.4)
7.50-8.17
<0.1-0.2
<1.0
0.76-2.19
<1.0(+0.3)
<1.0(+1.3)
<0.005
5.0-33.0
<0.01
34.2-150.0
6
6
6
6
6
6
6
3
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
5
3
6
6
6
6
6
6
6
6
6
5
6
6
231
0.48
0.16
<0.003
<0.01
0.16
0.35
<0.01
<0.001
26.6
17.7
0.02
<0.05
<0.02
<0.01
0.53
4.2
5.5
0.07
<0.01
23.9
<0.01
<0.002
0.04
0.06
9.5
0.29
3.1
43.2
1.6
7.76
<0.1
<1.0
1.53
<1.0
<1.0
<0.005
16.2
<0.01
94.6
79
0.63
0.39
0.002
0.0
0.25
0.47
0.0
0.0
14.0
12.4
0.03
0.0
0.0
0.0
0.47
4.3
14.4
0.12
0.0
11.2
0.01
0.0
0.09
0.09
13.2
0.82
3.2
49.6
4.3
0.60
0.1
0.7
1.37
0.6
0.1
0.0
21.2
0.0
91 .1
152-310
<0.1-1.11
<0.1-0.55
<0. 003-0. 004
<0.01
<0.1-0.41
<0.1-0.82
<0.01
<0.001
12.6-40.6
5.3-30.0
<0. 01 -0.05
<0.05
<0. 02-0. 04
<0.01
0.07-1.0
<0.2-8.5
4.0-19.8
<0. 03-0. 19
<0.01
12.7-35.1
<0. 01 -0.02
<0.0002
<0. 01-0. 14
<0. 04-0. 14
<0.1-22.7
<0. 10-1. 10
<0.1-6.4
<1.0-92.8
<1.5-5.9
7.16-8.32
<0.1-0.2
<1.0
0.16-2.90
<1.0
<1.0
<0.005
<2.0-37.4
<0.01
3.5-185.7
4-157
-------
Table 4-5 Background water quality 1n alluvial aquifer, Honument
Valley site (Concluded)
Constituent
Strontium
Sulfate
Sulflde
Thor1um-230b
Tin
Total dissolved
solids
Uranium
Vanadium
Z1nc
Observed
concentration
range3
<0.10
55.8-158.0
<0.10
0.0-6.3(+0.7)
<0.005
294.0-626.0
<0. 003-0. 0054
<0. 01-0. 70
<0. 005-1. 6
No. of
analyses
6
6
6
6
6
6
6
6
6
Mean*
<0.10
113.0
<0.10
1.2
<0.005
454.5
0.0034
0.30
0.5
Two
standard
deviations3
0.0
90.5
0.05
5.03
0.0
253.2
0.0024
0.66
1.4
Background
concentration
range3
<0.10
22.5-203.5
<0.10
<1.0-6.2
<0.005
201.3-707.7
<0. 003-0. 0059
<6. 01-0. 97
<0. 005-1. 8
aln mg/1 unless otherwise noted.
&For radlonuclldes, observed range plus analytical
background range, 1n plcocurles per liter.
error Is shown as the
4-158
-------
Table 4-6 Background water quality, Shlnarump and OeChelly Sandstone
aquifers at Monument Valley
Constituent
Concentration
1n Sh1narumpa
Concentration
1n OeChelly*
Alkalinity (as CaC03)
Aluminum
Ammonium
Antimony
Arsenic
Barium
Boron
Bromide
Cadmium
Calcium
Chloride
Chromium
Cobalt
Conductance''
Copper
Cyanide
Fluoride
Gross alpha0
Gross betac
Iron
Lead
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Nitrate
Nitrite
Nitrate & Nitrite (as N)
Organic carbon
Lead-210c
pHd
Phosphate (as P)
Polon1um-2lOc
Potassium
Rad1um-226c
Rad1um-228C
Selenium
Silica
Silver
Sodium
Strontium
Sulfate
202-220
0.20-0.80
<0. 10-0. 26
<0. 003-0. 005
<0.01
<0. 10-0. 20
0.10-0.50
<0.01
<0.001
3.0-29.2
7.0-15.0
<0. 01 -0.02
<0.05
400-700
<0.02
<0.01
0.20-0.80
0.50-22.0
3.2-12.0
<0. 03-0. 33
<0.01
15.1-20.3
<0. 01-0. 10
<0.0002
<0. 01-0. 22
<0. 04-0. 11
0.5-13.29
<0. 10-1. 65
0.3-3.3
42.0-51.0
0.1-3.7
7.1-8.4
<0. 10-0. 60
0.00-0.60
1.41-3.99
0.10-8.6
0.00-0.50
<0.005
9.0-13.0
<0.01
73.7-94.9
<0.10
72.0-128.0
97-198
0.30-0.80
<0.10
<0. 003-0. 004
<0.01
<0. 10-0. 20
0.10-0.90
<0.01
<0.001
6.34-31.7
5.0-10.0
<0. 01 -0.04
<0. 05-0. 06
210-550
<0.02
<0.01
0.20-0.60
1.0-6.10
4.4-8.0
<0. 03-0. 10
<0.01
17.0-28.0
<0. 01-0. 05
<0.0002
<0. 01-0. 18
<0. 04-0. 11
1.0-22.0
<0. 10-1. 65
1.3-2.5
22.0-53.0
0.0-1.2
7.4-9.4
<0. 10-0. 30
0.00-0.40
1.55-5.25
0.00-0.30
0.00-0.60
<0.005
5.0-11.0
<0.01
6.4-50.2
<0.10
13.2-62.1
4-159
-------
Table 4-6 Background water quality, Shlnarump and DeChelly Sandstone
aquifers (Concluded)
Concentration Concentration
Constituent 1n Shlnarump* \j\ DeChelly3
Sulflde <0.10 <0.10
Temperature °C 13.0-20.0 15.0-19.0
Thor1um-230C 0.00-0.20 0.00-0.40
Tin <0.005 <0.005
Total dissolved solids 348.0-418.0 158.0-321.0
Total organic halogens <0.003-0.007 <0.003
Uranium 0.002-0.008 0.001-0.008
Vanadium <0.01-0.60 <0.01-0.80
Z1nc <0.005-0.09 <0,010-1.26
aAs mg/1 unless otherwise noted.
bumhos/cm2.
cP1cocur1es per liter.
^Standard units.
4-160
-------
TO HALCHlTA AN3
MEXICAN HAT
^
n
I
INDIAN SERVICE
ROUTE 6440
•TO MONUMENT
NO. 2 MINE
• 57
EVAPORATION
POND
'»
«
»
«k
LEGEND
• RESIDENCE
• DOE ALLUVIAL MONITOR WELL
-VSULFATE ISOPLETH Img/l)
Ji> dashed where estimated
k
\
'-/
•I
A
II .
If ';
If I
' \
K \
n
u _
1 '/ «*
\ •" -*
\ •// ~<
' H */
/—--,'.' *(
'"""•" ^ )
" */
n <
U T-/
/;' ".
* ^
// )
" /
" /
i */ /
i * '
J .1
500
500
15CC
APPROXIMATE SCAcE IN FE.ET
FIGURE 4-5
SULFATE PLUME, MONUMENT VALLEY SITE
4-161
-------
••*
I
INDIA
ROJTE 644
•TO MONUMENT
NO 2 MINE
LEGEND
• RESIDENCE
• DOE ALLUVIAL MONITOR WELL
.QX NITRATE ISOPLETH (mg'l as N)
* (dashed where estimated)
* EPA DRINKING WATER LIMIT
APPROXIMATE SCA..E IN FEET
FIGURE 4-6
NITRATE PLUME, MONUMENT VALLEY SITE
4-162
-------
//
TO HALCHiTA AND
MEXICAN HAT
\
PI
I
INDIAN SERVICE
ROUTE 6440
•TO MONUMENT
NO. 2 MINE
LEGEND
RESIDENCE
DOE ALLUVIAL MONITOR WELL
t
WELL URANIUM ISOPLETH {mg/ll
(dished where estimated)
.005
APPROXIMATE SCALE IN FEET
FIGURE 4-7 URANIUM PLUME, MONUMET VALLEY SITE
4-163
-------
Table 4-7 Sampling for Hazardous Constituents
in Uranium Mill Tailings Liquids^3)
Volatile Organic Compounds Not Found in Tailings Liquids
Bromoform
Carbon tetrachloride
Chlorobenzene
Chlorodibromomethane
Chloroform
Dichlorobromomethane
1,2 - dichloroethane
1,1,2,2 - tetrachloroethane
Tetrachloroethylene
1,1,1 - trichloroethane
1,1,2 - trichloroethane
Trichloroethylene
Semivolatile Organic Compounds Not Found in Tailings Liquids
2-Chlorophenol
2,4-Dichlorophenol
2,4-Dimethylphenol
4,6 - Dinitro-0-Cresol
2,4-Dinotrophenol
2-Nitrophenol
4-Nitrophenol
P-Chloro-M-Cresol
Pentachlorophenol
Phenol
2,4,6-Trichlorophenol
Acenaphthene
Acenaphtylene
Anthracene
Acenaphtylene
Anthracene
Benzidine
Benzo(a)anthracene
Benzo(a)pyrene
3,4-Benzofluoranthene
Benzo(ghi)Perylene
Benzo(k)fluoranthene
Bis(2-Chloroethoxy) Methane
Bis(2-Chloroisopropyl Ether
Bis(2-Chloroisopropyl) Ether
Bis(2-Ethylhexyl) Phthalate
4-Bromophenyl Phenyl
Butyl Benzyl Phthalate
2-Chloronaphthalene
4-Chlorophenyl Phenyl Ether
Chrysene
Dibenzo(a,h)Anthracene
1,2-Dichlorobenzene .
1,3-Dichlorobenzene
Fluoranthene
Fluorene
Hexachlorobenzene
Hexachlorobutadiene
Hexa'chlorocyclo-pentadiene
Hexachloroethane
Indeno (1,2,3-cd)pyrene
Isophorene
Naphthalene
Nitrobenzene
N-Nitrosodimethylamine
N-Nitrosodi-N-Propylamine
N-Nitrosodiphenylamine
Phenantrhene
Pyrene
1,2, 4-TriChlorobenzene
Aldrin
Alpha-BHC
Beta-BHC
Gamma-BHC
Delta-BHC
Chlordane
4,4-DDT
4,4-DDE
4,4-DDD
Dieldrin
Alpha-Endosulfan
Beta-Endosulfan
Endosulfan Sulfate
Endrin
Endrin Aldehyde
Heptachlor
Heptachlor Epoxide
PCB-1242'
4-164
-------
Table 4-7 (continued)
1/4-Dichlorobenzene PCB-1254
3,3'-Dichlorobenzidine PCB-1221
Diethyl Phthalate PCB-1232
Dimethyl Phthalate PCB 1248
Di-N-Butyl Phthalate PCB-1260
2,4-Dinitrotoluene PCB-1016
2,6-Dinitrotoluene Toxaphene
Di-N-Octyl Phthalate
1,2-Diphenylydrazine
(as Azobenzene)
Hazardous Constituents Found in Tailings Liquids
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cyanide
Fluorine
Lead
Mercury
Molybdenum
Nickel
Radium 226 and 228
Selenium
Thorium
Uranium
(a) from (SM87)
4-165
-------
Early work in solvent extraction was reviewed by Flagg
(F161). In the early 1940s diethyl ether was used to purify
uranium in the first large scale application of solvent
extraction in hydrometallurgy. Flagg groups the organic
extractants into organophosphorous compounds, as used in the
Dapex process, and organonitrogen compounds, amines, as used in
the Amex process. Flagg also reports that there was "very
extensive research" in the development of several organic
extractants for recovering uranium from sulfuric acid leach
liquors. Thus, it appears reasonable to assume that several
organic compounds were used at uranium mills, probably in the
1940s and 1950s.
4-166
-------
4.16 Analysis of Ground Water Classification
4.16.1 EPA's Ground Water Strategy
In August 1984, the Agency issued a Ground-Water Protection
Strategy, setting out the Agency's plans for enhancing ground
water protection efforts by EPA and the States (EPA 84). A
central feature of the Strategy is a policy framework for EPA's
programs which accords differing levels of protection to ground
water based on its use, value to society, and vulnerability to
contamination.
Dividing ground water into three classes, the policy
provides an extra degree of protection to ground water that is
highly vulnerable to contamination and of great value because of
its importance as a source of drinking water or its contribution
to a unique ecological habitat (Class I). The vast majority of
the nation's ground water is expected to fall within Class II, a
current or potential source of drinking water, and it is for
this ground water that basic EPA ground water protection
requirements are designed. Class III ground water is not a
potential source of drinking water due to levels of
contamination from naturally occurring conditions or the effects
of broadscale human activity that cannot be feasibly cleaned up.
As an initial step is carrying out this policy, the Agency
has developed draft Guidelines (EPA 86a) for classifying ground
water which:
o Further define the classes, concepts, and key terms
related to the classification system outlined in the
Ground Water Protection Strategy, and
o Describe the procedures information needs for
classifying ground water.
The classification system is, in general, based on drinking
water as the highest beneficial use of the resource. The system
is designed to be used in conjunction with the program offices
in issuing permits and deciding on appropriate remedial action.
A site-by-site approach to classifying ground water
necessitates delineating a segment of ground water to which the
classification criteria apply. Since EPA is not classifying
ground water on a regional or aquifer-specific basis, a
Classification Review Area concept is incorporated as a key
element in the classification decision. This is, however,
4-167
-------
strictly an area for review of ground-water characteristics and
not an area where regulation will be imposed beyond that of the
specific activity under consideration.
The Classification Review Area is delineated based
initially on a two-mile radius from the boundaries of the
"facility" or the "activity." An expanded Classification Review
Area is allowed under certain hydrogeologic conditions. Within
the Classification Review Area, a preliminary inventory of
public water-supply wells, populated areas not served by public
supply, wetlands, and surface waters, is performed. The
classification criteria are then applied to the Classification
Review Area and a classification determination made.
For purposes of this discussion, the Classification Review
Area encompasses that area having contaminated ground water
whose source of contaminants is the uranium mill tailings piles.
Following is a summary of the key criteria for each class
and procedural approaches for determining whether the criteria
are met.
Class I - Special Ground Water
Class I ground waters are defined as resources of particularly
high value. They are highly vulnerable and either an
irreplaceable source of drinking water or ecologically vital.
o Highly vulnerable ground water is characterized by a
relatively high potential for contaminants to enter and/or be
transported within the ground-water flow system. The draft
Guidelines provide two options for determining vulnerability
based on hydrogeologic factors. Option A uses a standard
numerical ranking system known as DRASTIC, with numerical cutoff
points. Option B relies on a qualitative "best professional
judgment" approach which could include use of numerical or
alternative techniques.
o An irreplaceable source of drinking water is ground
water that serves a substantial population and whose replacement
by water of compatible quality and quantity from alternative
sources in the area would be economically infeasible or
precluded by institutional barriers. There are two options for
judging irreplaceability. Option A relies on a standard
numerical ranking system known as DRASTIC, with numerical cutoff
points. Option B relies on a qualitative "best professional
judgment" approach which could include use of numerical or
alternative techniques.
4-168
-------
o Ecologically vital ground water supplies a sensitive
ecological system located in a ground water discharge area that
supports a unique habitat. Unique habitats include habitats for
endangered species listed or proposed for listing under the
Endangered Species Act as well as certain Federally managed and
protected lands.
Class II - Current and Potential Sources of Drinking Water and
Ground Water Having Other Beneficial Uses
Class II ground waters include all non-Class I ground water that
is currently used or is potentially available for drinking water.
Subclass IIA is a current source of drinking water. Ground
water is classified as IIA if there is either (1) one or more
operating drinking water wells or springs, or (2) a water supply
reservoir watershed or portion that is designated for water
quality protection by either a State or locality.
Subclass IIB is a potential source of drinking water. This
ground water (1) can be obtained in sufficient quantity to meet
the needs of an average family (i.e., 150 gallons per day); (2)
has total dissolved solids (TDS) of less than 10,000 milligrams
per liter (mg/1); and (3) is of a quality that can be used
without treatment'or that can be treated using methods
reasonably employed by public water systems.
Class III - Ground Water Not a Potential Source of Drinking
Water and of Limited Beneficial Use
The draft Guidelines de.fine Class III ground water to
encompass those waters which are not potential sources of
drinking water due to:
1) salinity (i.e., greater than 10,000 mg/1 total dissolved
solids),
2) contamination, either by natural processes or by human
activity (unrelated to a specific pollution incident), that
cannot be cleaned up using treatment methods reasonably employed
in public water-supply systems (or economically treated), or
3) insufficient yield at any depth to provide for the needs
of any average-size household.
4- 169
-------
Subclasses are differentiated based primarily on the degree
of interconnection to adjacent waters (i.e., surface waters
and/or ground water of a higher class).
Subclass IIIA ground water has an intermediate degree of
interconnection with adjacent ground water or a high to
intermediate degree of interconnection with surface water.
Subclass IIIB ground water has a low degree of inter-
connection with adjacent surface waters or ground waters.
The key terms and concepts underlined above are defined in
this section.
Methods Reasonably Employed in Public Water Treatment Systems
Ground water may be considered "untreatable" if, in order
to meet primary drinking water standards and other relevant
Federal criteria or guidelines, treatment techniques not
included on a reference list of commonly applied technologies
must be used. The focus on public-water system techniques
(rather than all technologies) was established in the Ground
Water Protection Strategy. The reference list has been designed
to account for variations in the use, availability, and
applicability of treatment technologies in an EPA Region. This
approach is a relatively simple decision framework that does not
involve detailed engineering or cost analyses. An optional
approach which focuses on treatment costs compared with total
system costs is presented for review and comment in the draft
guidelines report, (EPA 86a).
For application to the classification system, EPA has made
an inventory of all known or potential water treatment
technologies and classified each as belonging to one of three
categories:
o Methods in common use that should be considered treatment
methods reasonably employed in public water treatment systems,
o Methods known to be in use in limited number of cases
that may, in some regions because of special circumstances, be
considered reasonably employed in public water treatment
systems/ and
o Methods not in use by public water treatment systems.
4-170
-------
Methods in common use include aeration, air stripping,
carbon adsorption, chemical precipitation, chlorination,
flotation, fluoridation, and granular media filtration.
Methods known to be used under special circumstances
include: desalination (e.g., reverse osmosis, ultrafiltration,
and electrodialysis), ion exchange, and ozonization. In most
EPA Regions, these treatment methods should not be considered
methods reasonably employed by public water systems. In certain
EPA Regions, because of special ground-water quality or water
scarcity circumstances, they may be considered reasonably em-
ployed.
Treatment methods not in use by public water treatment
systems include: distillation and wet air oxidation. These
methods are considered new to water treatment although they have
been applied for industrial purposes in the past. Since their
application to water treatment is experimental at this time,
they should not be considered treatment methods reasonably
employed in public water systems.
It should be stressed that some techniques such as granular
media filtration are used by public water treatment plants for
polishing (e.g., final treatment). These techniques may be
insufficient to adequately treat heavily contaminated ground
water. In such cases, where unrelated to a given source of
pollution, a Class III designation is likely. In other cases
where the listed treatment techniques are in use and would be
equally effective and insignificantly more costly to apply to
the contaminant under consideration, the water would considered
"reasonably treatable" and not Class III.
Treatment capacity to handle certain concentrations or
combinations of contaminants may not be employed in a region,
although the basic technologies are available. In these cases,
the optional economics-based tests may be preferential to the
reference technology approach.
Insufficient Yield at Any Depth
In order to establish Subclass IIIA on the basis of
insufficient yield, two conditions must be met:
(1) There are no wells or springs used as a source of
drinking water regardless of well yield.
(2) All water-bearing units meet the insufficient yield
criterion.
4- 171
-------
Given variability in regional aquifer characteristics and
climate, a value of 150 gallons-per-day was selected as the
cutoff for sufficiency. This level of production should be
possible throughout the year, in order to qualify as a potential
source of drinking water. The yield can be obtainable from
drilled wells, dug wells, or any other method. Agricultural,
industrial, or municipal uses of these marginal water-bearing
areas would require significantly higher yields than a domestic
well and would, therefore, be unable to use this low-yield
ground water as a water source. The figure is based on a
conservatively low yield below which it is .considered unlikely
or impractical to support basic household needs.
In setting the sufficient yield criterion, EPA consulted
its own guidelines concerning water needs and related waste
flows for single family dwellings. EPA's water-supply
guidelines indicate that per capita residential water needs
range from 50 to 75 gallons-per-day (EPA, 1975) for a single
family residence. Waste flows from single family dwellings
using septic systems average 45 gallons-per-day per capita (EPA,
1980, page 51). Using an average family size and a per capita
water need of approximately 50 gallons-per-day, the well-supply
criterion was established at approximately 150 gallons-per-day.
Interconnection and Ground Water Units
The subclasses of Class III ground water are differentiated
in part by the relative degree of interconnection between these
waters and those in adjacent ground-waters of a higher class
and/or surface waters. Subclass IIIA ground-water units are
defined to have an intermediate degree of interconnection to
adjacent ground-water units or a high to intermediate degree of
interconnection to adjacent surface waters. Subclass IIIB
ground-water units are defined to have a low degree of
interconnection to adjacent ground waters or surface waters.
Subdivision of the contaminated area is allowed in order to
recognize naturally occurring ground-water bodies that may have
significantly different use and value. For purposes of
subdividing the review area, these ground-water bodies, referred
to as "ground-water units", must be characterized by a degree of
interconnection (between adjacent ground-water units) such that
an adverse change in water quality to one ground-water unit will
have little likelihood of causing an adverse change in water
quality in the adjacent ground-water unit. Each ground-water
unit can be treated as a separate subdivision of the
contaminated area. A classification decision is made only for
the ground-water unit or units potentially impacted by the
activity.
4- 172
-------
The concepts of ground-water units and the interconnection
between adjacent ground-water units are particularly important
to classification. First, the degree of interconnection to
adjacent ground-water units and surface waters is a criterion
for differentiating between subclasses of Class III ground
waters. Second, the delineation of ground-water units
establishes a spatial limit for classification and the
application of protective management practices. Hydrogeologists
routinely assess the interconnection between bodies of ground
water for such purposes as designing water-supply systems,
monitoring systems, and corrective actions of contaminated
water. Where ground-water bodies are shown to be poorly
interconnected, it is possible to spatially distinguish between
their use and value. Waters within a ground-water unit are
inferred to be highly interconnected and, therefore, a common
use and value can be determined. As a consequence, it is
possible to selectively assign levels of protection to specific
ground-water units to reflect differences in use and value.
Protection applied to adjacent ground-water units will have
little beneficial effects.
The identification of ground-water units and the evaluation
of interconnection between ground-water units may, in critical
cases, require a rigorous hydrogeologic analysis. The analysis
may be dependent upon data collected off site that is not part
of the readily available information normally used in a
classification decision. For these reasons, the acceptance of
subdivisions will be on a case-by-case basis after review of the
supporting analysis.
Ground-Water Units
Ground-water units .are components of the ground-water
regime, which is defined as the sum total of all ground-water
and surrounding geologic media (e.g., sediment and rocks). The
top of the ground-water regime would be the water table; while,
the bottom would be the base of significant ground-water
circulation. Temporarily perched water tables within the vadose
zone would generally not qualify as the upper boundary of the
regime. The Agency recognizes that upper and lower boundaries
are sometimes difficult to define and must be based on the best
available information and professional judgment.
4-173
-------
The ground-water regime can be subdivided into mappable,
three-dimensional, ground-water units. These are defined as
bodies of ground water that are delineated on the basis of three
types of boundaries as described below:
Type 1: Permanent ground-water flow divides. These flow
divides should be stable under all reasonably
foreseeable conditions, including planned
manipulation of the ground-water regime.
Type 2: Extensive, low-permeability (non-aquifer) geologic
units (e.g., thick, laterally extensive confining
beds), especially where characterized by favorable
hydraulic head relationships across them (i.e.,
the direction and magnitude of flow through the
low-permeability unit). The most favorable
hydraulic head relationship is where flow is
toward the ground-water unit to be classified and
the magnitude of the head difference (hydraulic
gradient) is sufficient to maintain this direction
of flow under all foreseeable conditions. The
integrity of the low-permeability unit should not
be interrupted by improperly constructed or
abandoned wells, extensive, interconnected
fractures, mine tunnels, or other apertures.
Type 3: Permanent fresh water-saline water contacts
(saline waters being defined as those waters with
greater than 10,000 mg/1 of Total Dissolved
Solids). These contacts should be stable under
all reasonably foreseeable conditions, including
planned manipulation of the ground-water system.
Interconnection
The type of boundary separating ground-water units reflects
the degree of interconnection between those units. Adjacent
ground-water units demarcated on the basis of boundary Type 2
are considered to have a low degree of interconnection. A low
degree of interconnection implies a low potential for adverse
changes in water quality within a ground-water unit due to
migration of contaminated waters from an adjacent ground-water
unit. A low degree of interconnection is expected to be
permanent, unless improper management causes the
low-permeability flow boundary to be breached. The lowest
degree of interconnection occurs where a Type 2 boundary
separates naturally saline waters from overlying fresh waters
(less than 10,000 mg/1 TDS), and the hydraulic gradient (flow
direction) across the boundary is toward the saline waters.
4-174
-------
Adjacent ground-water units demarcated on the basis of
boundary Type 1 and 3 are considered to have an intermediate
degree of interconnection. An intermediate degree of
interconnection also implies a relatively low potential for
adverse changes in water quality within a ground-water unit due
to migration of contaminated waters from an adjacent
ground-water unit. Type 3 boundaries/ however, are
characterized by a diffusion zone of fresh water-saline water
mixing that will be affected by changes in water quality in
either of the adjacent ground-water units. Type 2 and 3
boundaries are also prone to alteration/modification due to
changes in ground-water withdrawals and recharge.
A high degree of interconnection is inferred when the
conditions for a lower degree of interconnection are not
demonstrated. High interconnection of waters is assumed to
occur within a given ground-water unit and where ground water
discharges into adjacent surface waters. A high degree of
interconnection implies a significant potential for
cross-contamination of waters if a component part of these
settings becomes polluted.
The draft Guidance on Remedial Actions for Contaminated
Ground Water at Superfund Sites (EPA86b) offers further guidance
on Class III ground water restoration. If a Superfund site has
ground waters with Class III characteristics (i.e., ground water
that is unsuitable for human consumption), alternatives should
be developed based on the specific site conditions.
Environmental receptors and systems must be considered when
evaluating alternatives for contaminated Class III ground waters
to ensure that no adverse environmental impacts occur. In
ground waters with Class III characteristic, environmental
protection may determine the necessity and extent of ground
water remediation. In general, alternatives for Class III
ground waters will be relatively limited and the evaluation less
extensive than for Class I or II ground waters.
4.16.2 Ground Water Classification at Inactive Mills
A review of preliminary data summarized above indicates
large differences in ground water quality and characteristics
among the 12 sites. Ground water appears contaminated at most
sites. The most prevalent contaminants are uranium, molybdenum,
and nitrates among the hazardous constituents and sulfates among
the secondary contaminants. Ground water yields in shallow
wells exceed 150 gallons per day except at one site. Ground
water at some sites appears to be contaminated from sources
other than uranium tailings piles.
4-175
-------
Based on this review of preliminary data from the 12 sites,
it appears that the ground water at four sites may be Class III
(EPA84, EPA86a). Further examination of the ground water at
each site is needed before decisions can be made on
classification at each site.
4-176
-------
4.17 References (Chapter 4)
DOE84 U.S. Department of Energy, "Draft Environmental
Assessment of Remedial Action at the Gunnison Uranium
Mill Tailings Site," Dec 1984.
DOE86 U.S. Department of Energy, "Remedial Action Plan and
Site Conceptual Design for Stabilization of the
Inactive Uranium Mill Tailings Site at Monument Valley,
Arizona," Feb 1986.
EPA84 Environmental Protection Agency, "Ground Water
Protection Strategy," Washington, Aug. 1984.
EPA86a Environmental Protection Agency, "Guidelines for Ground
Water Classification under the EPA Ground Water
Protection Strategy," Final draft, Washington, Dec.
1986.
EPA86b Environmental Protection Agency, "Guidance on Remedial
Actions for Contaminated Ground Water at Superfund
Sites," EPA Contract No. 68-01-7090, Oct. 1986.
F161 Flagg, J.F., "Chemical Processing of Reactor Fuels,"
Academic Press, 1961.
Le87 Leske, D., Department of Energy, Albuquerque Operations
Office, private communication, June 1987.
NUREG-0706
Sm87
U.S. Nuclear Regulatory Commission, Final Generic
Environmental Impact Statement on Uranium Milling,
NUREG-0706, Sept 1980.
Smith, R.D., U.S. Nuclear- Regulatory Commission,
"Sampling of -Uranium Mill Tailings Impoundments for
Hazardous Constituents," Memorandum to Robert E.
Browning, Director, Division of Waste Management, NMSS,
Feb 9, 1987.
4-177
-------
CHAPTER 5
GROUNDWATER RESTORATION
5.1 TREATMENT TECHNOLOGY
5.1.1 INTRODUCTION
The purpose of this chapter is to identify groundwater
restoration techniques that might be applicable to the removal
and treatment of contamination resulting from 12 Uranium Mill
Tailings Remedial Action (UMTRA) Project sites and to evaluate
the cost ranges of applying these techniques. The locations of
the 12 sites are shown in Figure 5.1. The groundwater treatment
technologies discussed in this summary are presently available
and applicable to hazardous wastes.
5.1.2 PROCESSES AND TECHNIQUES
Remedial actions that protect groundwater resources and
associated surface water resources include aquifer restoration,
elimination or limitation of the source of contamination, and
containment of the contaminated groundwater. EPA has mandated
long term, zero or minimal maintenance remedial actions for the
UMTRA Project sites (40 CFR 192). Therefore, aquifer restoration
and limitation of the source of contamination should be the
primary considerations. Containment of groundwater should be
considered only in support of aquifer restoration.
An appropriate water resource protection program at an UMTRA
Project site might include some or all of the following:
- Physical removal of contaminated groundwater
- Temporary containment of contaminated groundwater, intruding
uncontaminated groundwater or intruding surface water
- Treatment of contaminated water to meet appropriate water
quality standards or goals
- Isolation of the contaminant source from the hydrologic
regime
Isolation or at least partial isolation of the source of
contamination is implemented by the use of a multi-layered cover
above the source of contamination and possibly a layer of
selected and reworked natural materials underlying the source of
contamination. This approach is used to limit future
contamination to non-pollutant levels and is not related directly
to aquifer restoration. Therefore, this chapter will not discuss
further the repository designs but will focus on the processes,
5-1
-------
I
NJ
GRAND JCT
GUNNISON
DURANGO
SHIPROCK
MONUMENT •
•
TUBA CITY
FIGURE 5.1 LOCATION OF THE 12 UMTRA SITES
-------
technologies and costs of aquifer restoration as related to 12
UMTRA Project sites.
Physical Removal
Two methods can be used to remove contaminated groundwater:
trenches and wells. The methodologies and technical
considerations are discussed in this section.
Subsurface Drains/Trenches
Subsurface drains consist of underground gravel-filled trenches
lined with tile or perforated pipe which intercept leachate or
infiltrating water and transport it away from the wastes to a
suitable point for treatment and/or disposal. Subsurface drains
may be used in low permeability strata, such as clay or silty
clay with permeability insufficient to maintain adequate flow to
wells. The subsurface drain can provide a sufficient surface to
create greater discharge rates than a well or series of wells
could provide. Subsurface drains can also be used in more
permeable sand and gravel. For sand and gravel, an open trench
can be used or the permeability of the material in the trench
must be significantly greater than the surrounding soil to make
the trench effective.
Subsurface trenches are generally constructed by excavating a
trench, laying perforated pipe or tile along the bottom, and
backfilling with a coarse gravel to prevent soil fines from
penetrating and clogging the soil pores. This procedure is
confined to situations in which the contaminated groundwater is
at a depth consistent with the capabilities of the trenching
equipment, generally no more than 100 feet below the land
surface. Advantages of this type of system include low operating
costs, since flow is by gravity, considerable flexibility in
design and spacing, and fairly good reliability when monitoring
is provided.
Wells
Wells can be employed to extract or actively divert groundwater
at or near a disposal site and are effective in any porous or
fractured media which provide sufficient yields to wells. This
technology may be employed to collect the groundwater for
treatment, contain a contaminant plume, or to lower a water
table. The number, spacing, depths, diameters, and completion
intervals of wells in a well field can be optimized to remove
contaminated groundwater cost-effectively. The goals of a
restoration program should be developed and wells positioned to
remove the specified contaminated groundwater while extracting
only a limited volume of uncontaminated water.
5-3
-------
Pumping to lower a water table may be appropriate under several
conditions, such as 1) lowering the water table in an unconfined
aquifer so that contaminated groundwater does not discharge to a
hydraulically-connected receiving stream, 2) lowering the water
table so that it is not in direct contact with the waste, or 3)
lowering the water table to prevent contamination of an
underlying aquifer.
Temporary Containment
Physical containment is accomplished through installation of a
relatively impermeable barrier between contaminated and clean
portions of the aquifer. Physical containment technologies
include slurry walls, grout curtains, and sheet piling.
Containment should be considered as support for physical removal
of contaminated groundwater, rather than as a remedial action in
itself. Containment methods are not proven long term solutions,
therefore their application is limited to support of physical
removal at UMTRA Project sites. For instance, at sites adjacent
to rivers, such as the sites in Grand Junction and Durango,
containment may be considered in controlling surface water inflow
into the area of groundwater removal. Figure 5.2 shows the
effect of a cutoff wall adjacent to a river. Also, containment
may be appropriate where the advancing contaminant plume is
approaching a presently used water resource.
Sheet Pile Cut-Off Walls
The construction of a sheet pile cut-off wall involves driving
inter-locking piles into the ground with a pneumatic or steam
pile driver. When first placed in the ground, the sheet pile
cut-off allows easy water flow through the edge interlocks.
However, with time, fine soil particles fill the seams and an
effective barrier is formed. The performance life of a sheet
pile cut-off wall can vary between seven and 40 years, depending
upon the chemical characteristics of the surrounding soil. Sheet
piling is feasible in situations where the water table is near
the surface, a confining layer exists at a depth of less than 100
feet, and surficial materials are fine-grained to allow ease in
driving the sheet metal. Sheet piling is not feasible for use in
very rocky soils or for long-term containment.
Slurry Walls
Installation of a slurry wall involves excavating a trench
through or under a slurry of bentonite clay and water, then
backfilling the trench with the original soil (with or without
bentonite mixed in) . The trench is usually excavated down to a
relatively impervious substratum to limit groundwater underflow.
During the excavation process, the trench walls are supported by
the slurry, preventing the walls from slumping or caving in, and
5-4
-------
LOW-PERMEABIUTY BARRIER REDUCES INDUCED
FLOW FROM RIVER
t_n
I
Ln
DISCHARGING WELL
RIVER
PUMPING
WATER
LEVEL
ALLUVIAL AQUIFER
^- CONFINING LAYER
— LOW-PERMEABIUTY
SLURRY WALL. GROUT CURTAIN.
OR SHEET PILING CUTOFF WALL
FIGURE 5.2
-------
eliminating the need for additional shoring materials. The
process is designed to force the bentonite slurry through its own
weight into the more permeable surrounding soils, forming a
filter cake of low permeability which lines the walls and bottom
of the trench. The application of slurry walls as relatively
impermeable barriers is limited to areas where materials are
trenchable and have sufficient permeability to form a filter
cake. Trench depth is limited by the capabilities of the
trenching equipment. Thus, this technology is practical only
when groundwater contamination exists near the surface, generally
less than 100 feet in depth. Further, tests must be performed as
part of the remedial action process to determine whether the
slurry could be affected by chemical reactions with the
contaminants, thus rendering it unsuitable for application.
Slurry walls may be more appropriate for protecting surface water
from contamination of discharging groundwater rather than
containing the groundwater itself.
Grout Curtains
Grouting is the pressure injection of special fluids into a rock
or soil body. The fluids set or gel in the voids in the rock and
when carried out in the proper pattern and sequence, the process
forms a wall or curtain that is an effective groundwater barrier.
Due to the high cost of installing grout curtains, they are
usually used only to seal voids in porous or fractured rock where
other methods to control groundwater are not technically
feasible.
Treatment Processes
After contaminated groundwater has been collected, the next step
in aquifer restoration involves treatment of the water and the
eventual reinjection into the groundwater or discharge to surface
water. A variety of methods has been successfully employed in
treating groundwater contaminated with contaminants typical of
UMTRA Project sites (e.g. uranium, metals, sulfate and dissolved
solids). Examples are chemical precipitation, evaporation, ion
exchange, neutralization, and sorption.
Chemical Precipitation
The chemical precipitation process removes dissolved metals from
aqueous wastes by chemically converting the metals into insoluble
forms. The process is illustrated in Figure 5.3. Metals may be
precipitated from solution as hydroxides, sulfides, carbonates or
other salts. Hydroxide precipitation with lime is most common;
however, sodium sulfide is sometimes used to achieve lower
effluent metal concentrations. This involves pH adjustment
followed by the addition of sodium sul fide and a flocculant.
Solids separation is achieved by standard flocculation—
5-6
-------
CHEMICAL PRECIPITATION AND ASSOCIATED PROCESS STEPS
CHEMICAL
PRECIPfTANTS
LJQUID
-2-
PRECIPnATOR
TANK
CHEMICAL
FLOCCULANTS/
SETTLING AIDS
FLOCCULATON FLOCCULATING
WELL PADDLES
FLOCCULATOR-
CLARIRER
SLUDGE
FIGURE 5.3
-------
coagulation techniques. Th@ resulting residuals are metal sludge
and the treated effluent with an elevated pH and, in the case of
sulfide precipitation, excess sulfide.
This technology is used to treat aqueous wastes containing
metals, including zinc, arsenic, copper, manganese, mercury,
cadmium, trivalent chromium, lead and nickel. A disadvantage of
the method is that the pH which would precipitate one metal may
allow other metals to remain
soluble. Therefore, it may be difficult to attain an optimal pH
for a given mix of metals. Also, chelating or complexing agents
may prevent metals from precipitating. Sulfide precipitation has
been successfully used in numerous applications and often
achieves lower concentrations levels than lime precipitation.
However, the process does require close monitoring to function
properly.
Most UMTRA Project milling operations employed acid leach
processes to extract uranium. Therefore, chemical precipitation
initiated by increasing the pH can be very effective in reducing
the concentrations of radium, thorium, uranium, selenium,
arsenic, cadmium, chromium, other trace metals and sulfate.
Although some chemical precipitation resulted from neutralization
in the subsoils at most sites due to the abundance of calcite in
the soils, enhanced precipitation may be applied with a treatment
plant to further lower the concentrations of metals that complex
with mobile anions. Sulfide precipitation may be most effective
in this enhanced treatment.
Evaporation
Evaporation is defined as the physical' separation of a liquid
from a dissolved or suspended solid by the application, of energy
to volatize the liquid. Evaporation may be used to concentrate a
hazardous or toxic material, thus reducing the volume of waste
requiring subsequent treatment or disposal. Evaporation can be
carried out in a large pond with sunlight providing the energy.
Most UMTRA Project sites are in semi-arid climates where
potential evaporation greatly exceeds precipitation. Therefore,
a pond to evaporate discharged groundwater from dissolved
contamination is a potentially viable treatment technique.
Following evaporation, the residual solids could be incorporated
into the tailing repository for "permanent" disposal.
Ion Exchange
Ion exchange removes toxic metal ions from solution by exchanging
one ion, electrostatically attached to a solid resin material,
for a dissolved toxic ion. The process is illustrated in Figure
5.4. The resulting residuals include spent resins and spent
5-8
-------
FIGURE 5.4
SCHEMATIC OF ION EXCHANGE
TO STORAGE TANK OR
OTHER TREATMENT SYSTEM
TO STORAGE TANK OR
OTHER TREATMENT SYSTEM
INFLUENT
WASTEWATER
Q *•
BACKFIUSH
WATER
ACID
REGENERANT
CATION EXCHANGE
SYSTEM
BACKFIUSH
WATER
TREATED
WASTEWATER
CAUSTIC
REGENERANT
ANION EXCHANGE
SYSTEM
TO STORAGE TANK OR
OTHER TREATMENT SYSTEM
TO STORAGE TANK OR
OTHER TREATMENT SYSTEM
5-9
-------
regenerants such as acid, caustic or brine. This technology is
used to treat metal wastesincluding cations (Ni2+, Cd2+, Hg2+) and
anions (CrO42~, SeO42~, HAs042") . The effectiveness of the process
may be limited by competition for exchange sites between
contaminants and non-contaminated metals. Other disadvantages
are difficulties in obtaining and maintaining an optimal pH for
efficient removal and the inefficiency of the process in treating
groundwater with high concentrations of suspended solids. The
oxidizing agent concentration should be greater than 50 milli-
equivalent per liter (meq/1) for practical operation. Highly
concentrated waste streams (>2500 mg/1 contaminants) or high
solid concentrations (>50 mg/1) should be avoided.
Neutralization
Neutralization renders acidic or caustic wastes non-corrosive by
adjustment of the pH. The residuals include insoluble salts,
metal hydroxide sludge, and neutral effluent containing dissolved
salts. The final desired pH is usually between 6.0 and 9.0.
Neutralization is used to treat corrosive wastes, both acids and
bases. A disadvantage of the process is the need to dispose of
highly concentrated sludges and solids.
Significant neutralization occurs at UMTRA Project sites directly
beneath and downgradient of the tailings source material due to
calcite in the shallow soils. The neutralization causes
precipitation of gypsum and the coprecipitation, occlusion and
adsorption of radionuclides and trace metals.
Sorption
Contaminants are bound up in pozzolan-type matrices by physical
sorption or chemisorption yielding a stabilized material which is
easier to handle. The process is illustrated in Figure 5.5.
Liquid immobilization depends on added ingredients. This process
results in high concentrations of contaminants at the surface of
the material and contaminants may leach. The treated material is
permeable.
Sorption can be used for organics and inorganics. The advantages
to this technology are that raw materials are readily available,
the mixing technology is known, the waste form is relatively easy
to handle, additives are inexpensive, minimum pretreatment is
required, and bearing strength is adequate for landfill.
Disadvantages are that large volumes of additives are needed, the
results are sensitive to the placement and packing of the
matrices, free water may be released under pressure and changes
in temperature may affect the results.
5-10
-------
FIGURE 5.5
SCHEMATIC OF CARBON ADSORPTION
TO SERVICE
UQUID
FEED
FT
CARBON
ADSORPTION
COLUMN
H
SPENT CARBON
(ONE UNFT CHANGED
PER TIME)
CARBON
ADSORPTION
COLUMN
12
TO
REGENERATION
5-11
-------
Landfarming
Landfanning is a technique where contaminated soil is
incorporated into the top 6 to 8 inches of soil along with
concentrated microbial populations. It is used to biodegrade,
volatize or leach organics. It is not applicable to the
inorganic contamination at UMTRA Project sites (WESTON, 1983).
Reverse Osmosis
Reverse osmosis is a membrane process to remove dissolved ions
from saline water using hydrostatic pressure to drive the
feedwater through a semipermeable membrane. The major portion of
the ions remain on the feed side of the membrane and is
discharged as waste. The osmotic pressure needed for successful
treatment can be estimated as 1 psi/100 mg/1 of TDS.
Modern reverse-osmosis membranes are constructed in a modular
form, most common are spiral wound and hollow fine fiber. The
modules are mounted in containment pressure vessels. Reverse
osmosis is most successful in treating water with less than
10,000 mg/1 TDS to produce water with less than 500 mg/1, i.e.,
potable quality (Montgomery, 1985). The cost for reverse osmosis
ranges from $500 per million gallons treated for water containing
approximately 10,000 mg/1 TDS to $1500 per million gallons
treated for water containing approximately 30,000 mg/1 TDS
(Thompson, 1987).
5.2 TREATMENT TECHNOLOGIES AND COST RANGES APPLIED TO TWELVE
UMTRA PROJECTS SITES
5.2.1 INTRODUCTION
From a technical standpoint, three factors govern the
feasibility, effectiveness and costs of aquifer restoration.
These are 1) the volume of contaminated groundwater, 2) the ease
with which it can be removed, and 3) its treatability. When a
vast volume of groundwater is contaminated or when an aquifer is
hydraulically connected to a surface water body, it may neither
be technically nor economically feasible to pump, treat, and
recharge the contaminated wastes. Similarly, in a situation for
which the aquifer is thin, discontinuous, heterogeneous, or of a
low permeability, aquifer restoration also may not be feasible.
Finally, while it may be technically and economically feasible to
collect contaminated groundwater, it is possible that the type
and/or levels of contamination may not be treatable. These
factors must all be considered in selecting the scope of aquifer
restoration and the applicable technologies.
5-12
-------
5.2.2 SITE DESCRIPTIONS
In this section, each of the 12 sites is described, with emphasis
on the estimated volume of contaminated groundwater, the
appropriate method to extract the contaminated groundwater, and
the value of the contaminated groundwater relative to its present
or potential use.
Ambrosia Lake
The estimated volume of contaminated groundwater at the Ambrosia
Lake site is 675 million gallons. The tailings lie on
unconsolidated materials. The shallow groundwater occurs 10 to
40 feet beneath the ground surface. The deeper tailings are
saturated. The groundwater contained in the tailings, alluvium,
fractured Mancos Shale, and Tres Hermanos Sandstone probably
resulted from surface discharges of mine dewatering. Given that
the depth of contamination is relatively shallow and yields to
wells are minimal, contaminated groundwater could be extracted
more efficiently with trenches than with wells. Following
remedial action, given that mining and dewatering has ceased in
the area, the contaminated groundwater will probably dissipate
through discharge into the mine shaft in the Wastewater Canyon
Member of the Morrison Formation and the presently saturated
shallow zones will desaturate.
Canonsburq
The volume of contaminated groundwater at the Canonsburg site is
approximately 100 million gallons. The remedial action at the
Canonsburg site was completed in 1986. Groundwater at the
expanded Canonsburg site is unconfined in the unconsolidated
material (fill, soil, and alluvium) and is semi-confined in the
underlying bedrock. Given that the contamination is relatively
shallow, trenches would appear to be the preferred method for
groundwater removal. Depth to groundwater is zero to eight feet.
Recharge to the unconsolidated material is from direct
infiltration of precipitation and from groundwater flow onto the
expanded Canonsburg site from the south. Chartiers Creek is the
discharge area on the western, northern, and eastern sides of the
site for the unconfined groundwater. Groundwater in the shallow
bedrock may pass beneath the site. Groundwater in the area has
very limited use for gardening and other outdoor uses.
Durango
Subsurface investigations at the Durango site were limited by the
steep, unstable slopes of tailings and smelter slag at the site.
A rough estimate of the volume of contaminated groundwater at the
site is 500 million gallons. The depth to groundwater ranges
from approximately ten to 50 feet below land surface. The
5-13.
-------
contamination is primarily in the alluvium and is naturally
contained by a thick bed of Mancos Shale underlying the alluvium.
Trenching would be preferred over pumping to extract contaminated
groundwater due to the relatively shallow depth of contamination.
The site is within 500 feet of the Animas River. A cut-off wall
may be necessary during aquifer restoration to prevent the inflow
of surface water from the Animas River.
Grand Junction
The volume of contaminated groundwater at the Grand Junction site
is approximately 600 million gallons. Shallow unconfined
groundwater occurs in the alluvium on the Colorado River and is
separated from confined groundwater by approximately 200 feet of
relatively impermeable Mancos Shale. Shallow groundwater is not
used in the area. Most or all of the contaminated groundwater
could probably be removed with trenches. A cutoff wall may be
required during groundwater removal to limit the inflow of water
from the Colorado River. Return irrigation flow passes under and
possibly through the tailings pile. The water table over much of
the site rises above the base of the tailings. During most of
the year, shallow groundwater flows toward the Colorado River.
Water quality analyses indicate no river contamination due to
tailings seepage.
Gunnison
Approximately two billion gallons of groundwater are contaminated
at the Gunnison site. Shallow groundwater is the major water
supply in the Gunnison area. The Gunnison site rests on a
massive alluvial deposit that is more than 100 feet thick. It
rests at the confluence of two large regional groundwater
aquifers comprised of the Gunnison River and Tomichi Creek water
sheds. The depth of the groundwater varies by six to eight feet
annually and is near or above the base of the tailings during the
summer months. Contamination may be up to approximately 100 feet
deep. Because the contamination is relatively deep, covers a
broad area and the sediments are relatively permeable, pumping is
the preferred method for groundwater extraction for aquifer
restoration.
Lakeview
The estimated volume of contaminated groundwater at the Lakeview
site is three billion gallons. Groundwater at depths greater
than 100 feet is the major water supply in the Lakeview area.
The depth of contamination is approximately 50 to 75 feet below
land surface. Groundwater occurs under both confined and
unconfined conditions with a water table that varies seasonally
from zero to 15 feet below the ground. Because the contamination
is relatively deep and the sediments are relatively permeable,
5-14
-------
pumping is the preferred method for groundwater extraction for
aquifer restoration.
Mexican Hat
The estimated volume of contaminated groundwater at the Mexican
Hat site is 80 million gallons. The tailings rest on very dense,
tight siltstone. The Mexican Hat site is about five miles away
from the nearest exposure of permeable strata. Except for areas
of local ponding, the fine-grained nature of the tailings and the
high evaporation rates of the region allow only limited amounts
of precipitation to infiltrate into the tailings. Capillary
forces in the tailings may be sufficient to preclude percolation
of tailings water to the underlying bedrock. The depth to the
water table is not known but is assumed to be greater than 50
feet. Because the contamination is relatively deep, pumping
would be the preferred method to remove groundwater for aquifer
restoration. The ambient water quality is poor (only industrial
use is possible without extensive treatment).
Monument Valley
Approximately three billion gallons of contaminated groundwater
lie beneath and downgradient of the Monument Valley site.
Shallow groundwater is used by several local dwellers. The
tailing piles are all sand (no slime), all precipitation is
absorbed and there is little evidence of any surface runoff from
the piles. The rock unit that forms the shallowest confined
aquifer near the mill site is the Shinarump Conglomerate Member
of the Chinle Formation. This rock unit is exposed immediately
west of the tailings piles, and most of the abandoned mill
building foundations and settling pond sites are located on
outcrops. The Shinarump Member consists of poorly sorted sand,
grit, and pebble-size conglomerate. Unconfined groundwater is
very near the surface along the main axis of Cane Valley Wash.
The unconfined water moves through the alluvium of Cane Valley
Wash and is recovered near the site from shallow wells. These
shallow wells and springs are recharged from local runoff.
Contamination extends to depths of up to 100 feet. The depth and
large area of contaminated groundwater and relatively permeable
soil and rock indicate that pumping is the preferred method of
groundwater extraction for aquifer restoration.
Riverton
The volume of contaminated groundwater at the Riverton site is
approximately one billion gallons. Groundwater levels are
generally less than six feet below the tailings foundation
interface and periodically groundwater rises toward and into the
lower portions of the tailings pile. A confined aquifer system
is present in the underlying bedrock. The unconfined system and
5-15
-------
the first confined system are separated by about 25 feet
shale, siltstone, and mudstone bedrock. The unconfined
groundwater quality is briny and is not a source of potable
water. The unconfined aquifer has been contaminated.
Contaminated groundwater could be removed using trenches. The
confined groundwater is a major source of potable water in the
Riverton area. It has not been contaminated as indicated by most
of the site groundwater quality data.
Salt Lake Citv
The volume of contaminated groundwater at the Salt lake city site
is estimated to be 1.5 million gallons. The Salt Lake City site
is underlain by an unconfined aquifer which overlies a confined
aquifer. Both aquifers consist of interbedded clays, silts, and
sands. The shallow groundwater has been contaminated. Trenching
could be used to extract the contaminated groundwater.
Hydrologic data indicate the unconfined aquifer is about 60 feet
thick near the site. The unconfined aquifer is recharged by
upward leakage from the confined aquifer and infiltration of
precipitation and snowmelt. The confined aquifer is generally
encountered initially at a depth of about 75 feet. The major
source of recharge to this aquifer is infiltration of
precipitation and runoff from the foothills of the Wasatch
Mountains. The flow direction in both aquifers is to the west
and northwest. The confined aquifer has not been contaminated
significantly. The unconfined aquifer is characterized by very
high total dissolved solids, iron, sulfate, and sodium, and is
not usable as a potable water supply anywhere in the area. The
confined aquifer is potable and will continue to be used as a
water supply.
Shiprock
The volume of contaminated groundwater beneath the site is
estimated to be 850 million gallons and the contamination of the
floodplain deposits along the San Juan River is estimated to be
400 million gallons. Groundwater characterized by TDS in excess
of 20,000 ppm exists in the alluvial deposits and weathered
Mancos Shale between 13 and 50 feet below the surface underlying
the tailings repository. The relatively flat, shallow
groundwater gradient is towards the escarpment above the flood
plain of the San Juan River where only slight seepage has been
found. The shallow groundwater is contaminated beneath the
tailings; however, it is separated by hundreds of feet of
relatively impermeable Mancos Shale from the regional aquifer.
The contaminated groundwater in the floodplain deposits below
the escarpment along the San Juan River could be extracted with
trenches. Floodplain groundwater is used for all purposes by
local dwellers across the San Juan River from the site. Removal
of the contamination beneath the site may require pumping.
5-16
-------
Tuba Citv
Approximately 1.2 billion gallons of groundwater in the Navajo
Sandstone has been contaminated at the Tuba City site. The
principal aquifer and water supply in the Tuba City-Moenkopi area
is a multiple aquifer system consisting of Navajo Sandstone and
some sandstone beds in the underlying Kayenta Formation. This
aquifer is recharged by winter and spring precipitation in the
Kaibito Plateau highlands some distance north of Tuba City. The
depth to the water table is approximately 50 feet. Contamination
has extended to depths of up to 150 feet, therefore wells would
be needed to extract the contaminated groundwater.
5.2.3 AQUIFER RESTORATION COST RANGES
Unit costs ranges for groundwater removal methods, cut-off walls
and treatment methods are presented in Table 5.1. These costs
ranges are applied to each of the 12 sites, as follows:
o A choice is made whether trenches, or wells would be the
preferred method of groundwater removal. Then the unit cost
range is applied for the chosen method.
o Cut-off wall costs are applied for the two sites where river
inflow may need to be controlled.
o Site-specific treatment methods are not specified because
the unit cost ranges do not vary significantly between the
various treatment methods. A treatment cost range of $ 500
to $ 1400 per million gallons is used for each site.
Table 5.2 shows the results of the application of the unit costs
to each site. The minimum total costs are calculated using the
minimum estimated volumes of contaminated groundwater and the
minimum estimated unit costs. It is assumed that only one volume
of contaminated water needs to be extracted. The minimum cost
projection represent minimal or partial restoration. The maximum
total costs are calculated using the maximum estimated volumes of
contaminated groundwater and the maximum estimated unit costs.
It is assumed that 15 times the volume of contaminated
groundwater needs to be extracted in order to sufficiently
restore groundwater quality. The maximum cost projections
probably would supply complete restoration of mobile constituents
and possibly complete restoration for adsorbed constituents, such
as molybdenum. The likely total costs are calculated using the
average estimated volumes of contaminated groundwater and the
average unit costs. It is assumed that 5 times the volume of
contaminated groundwater needs to be extracted to restore
adequate groundwater quality.
5-17
-------
TABLE 5.1
GENERIC COST RANGES
TREATMENT METHODS
1) SLURRY WALL
2) GROUNT CURTAINS
3) SHEET PILINGS
4) SUBSURFACE DRAINS
5) EVAPORATION PONDS
6) GROUNDWATER PUMPING
7) CHEMICAL PRECIPITATION
8) ION EXCHANGE
9) NEUTRALIZATION
10) SORPTION
11) REVERSE OSMOSIS
TOTAL COST (DOLLARS)
54.00 - 110.00/CUBIC YARD
162.00 - 330.00/CUBIC YARD
15.00/SQ FT OF WALL
500.00 - 1000.00/MGAL TREATED
1.50 - 5.00/SQ FOOT OF POND
500.00 - 1500.00/MGAL TREATED
500.00 - 1200.00/MGAL TREATED
500.00 - 1000.00/MGAL TREATED
500.00 - 1200.00/MGAL TREATED
1000.00 - 1400.00/MGAL TREATED
500.00 - 1500.00/MGAL TREATED
5-18
-------
TABLE 5.2 AQUIFER RESTORATION COST RANGES MINIMUM, MAXIMUM AND LIKELY
SITE
ANQLNT OF CON-
TAMINATED UATER
PUMPING COSTS
1E+06
TRENCHING
1E+W6
COSTS CHEMICAL TREATMENT CUT OFF CONTAINMENT COSTS
lE+«6 UALL 1E+06
(N6AL)
HKWU5IH LHKE
CANONSBUR6
DURANGO
GRAND JUNCTION
GUNNISON
LAKEVIEU
MEXICAN HAT
MONUMENT VALLEY
RIVERTON
SALT LAKE CITY
SHIPROCK
TUBA CITY
NIN
5W
75
380
see
isee
25W
60
2500
am
1800
teee
teee
MAX
600
125
7ee
969
2580
3598
129
3500
1200
2000
1500
1590
MIN
0.75
1.25
8. 93
1.25
e.s
MAX
56.25
78.75
2.7
78.75
33.75
MIN
0.25
0.0375
8.15
e.25
8.4
0.6
0.5
MAX
12
1.875
10.5
13.5
IB
30
22.5
HIN
0.25
0.0375
0.15
0.25
0.75
1.25
0.03
1.25
0.4
0.6
0.5
0.5
(FT2)
MAX MIN MAX MIN MAX
ib.a
2.625
14.7 450ee seeee e.45 1.6
18.9 2e0w seeee 0.2 i
52.5
73.5
2.52
73.5
25.2
42
31.5
31.5
TOTAL COSTS
1E+66
MIN
0.5
0.075
e.75
0.7
1.5
2.5
0.06
2.5
0.8
1.2
1
1
MAX
£B. 8
4.5
26.8
33.4
108.75
152.25
5.22
152.25
43.2
72
54
65.25
Ln
1
VO
SITE
mmjbiH uwt
CANONSBUR6
DURANGO
GRAND JUNCTION
GUNNISON
LAKEVIEU
MEXICAN HAT
MONUMENT VALLEY
RIVERTON
SALT LAKE CITY
SHIPROCK
TUBA CITY
AMOUNT OF CON- PUMPING COSTS TRENCHING COSTS CHEMICAL TREATMENT
TAMINATED UATER
(NGAL)
LIKELY
100
see
708
2088
3000
98
3eee
1000
1688
1258
1258
iE*e6
LIKELY
11.25
16.25
8.525
16.25
6.875
1E+06
LIKELY
0.40625
2.125
2.875
4
6.5
5
1E+86
LIKELY
3.425
8.53125
2.825
3.775
18.625
15.375
8.495
15.375
5.2
8.5
6.5
6.5
CUTOFF
UALL
(FT2)
LIKELY
62588
35000
CONTAINMENT COSTS
1E+06
LIKELY
1.391666
0 666666
TOTAL COSTS
1E+86
LIKELY
b. 05
0.9375
6.341666
7.316666
21.875
31.625
1.82
31.625
9.2
15
11.5
13.375
UNIT Lite Ib (DOLLARS)
IltR
HIN.
MAX.
LIKELY
CONTAINMENT
-------
The cost estimates include the major items required in an aquifer
restoration program. Some of the items not included in the cost
estimates are:
- monitoring equipment
- data collection
- discharge or reinjection facilities and operations
- removal and remediation of facilities
- final revegetation and well abandonment
5.3 REFERENCES
Clean-up of Chemical Contaminated Site, Chemical Engineering,
February 21, 1983, V90, n4, p.73(9)
Handbook, "Remedial Action at Waste Disposal Sites." USEPA, EPA
625/6-82-006
Handbook, "Leachate Plume Management." USEPA, EPA 5-40/2-85/004
Jacobs Engineering Group, "Aquifer Protection and Restoration
Alternatives and Cost Considerations"
Lauch, R.P., and Cuter, G.A., "Ion Exchange for the Removal of
Nitrate From Well Water." Journal AWWA, 78:5:83, May 1986
Montgomery, James M. "Water Treatment Principles and Design",
John Wiley & Sons, Inc., 1985.
Sorg, T.J., "Treatment Technology to Meet the Interim Primary
Drinking Water Regulations for Inorganics," Journal AWWA,
70:2:105, February 1978
Summary Report, "Remedial Response at Hazardous Waste Sites,"
USEPA, EPA 540/2-84-002 A & B
Thompson, Bruce, Personal Communication, University of New
Mexico, May 1987.
Roy F. Weston, "Installation Restoration General Environmental
Technology Development," Report No. DRXTH-TE-CR-83249, December
1983.
Roy F. Weston, "Solvent and Heavy Metals Removal from
Groundwater," Report No. DRXTH-TE-CR-82176, January 1983.
5-20
-------
Environmental Assessment of Remedial Action at the Riverton
Uranium Mill Tailings Site, U.S. Department of Energy, DOE/EA-
0254, July 1985
5-21
-------
Chapter 6
Costs of Ground-water Restoration
The costs of ground-water restoration can vary greatly
among sites, as discussed in the previous chapter. The purpose
of this chapter is to consider the major capital and operation
cost components and to extrapolate those costs to arrive at a
single estimate of the total ground water cleanup cost for all
24 sites. The major cost components are the amount of
contaminated ground water, the amount of contaminated ground
water that must be removed from below the surface, and any
treatments that must be given the contaminated ground water.
6.1 Amount of Contaminated Ground Water
The volume of ground water that is contaminated is
estimated from well data and the geological structure in the
locale of the tailings pile. Well data indicate the area of the
contaminated plume and also provide some of the local geological
characteristics. The presence of confining layers (aquitards)
limits the vertical spread of the contamination, unless there
are interconnections with other aquifers. The vertical distance
between confining layers when combined with the area of the
contaminated plume yields the volume of the contaminated
aquifer. The volume of the water is determined using the
porosity of the rocks in the aquifer.
The many variables in this determination leads to
uncertainty. The uncertainties in the amount of contaminated
water shown in Table 5.2 range from +_ 17% to +_ 40% from the
midpoint values. Since there is no evidence that these volumes
are skewed (i.e., purposefully over- or under-estimated), the
midpoint values are used to estimate total costs. The volumes
of contaminated ground water are listed in Table 6.1.
6.2 Amount of Ground Water to be Removed
The total cost of ground-water restoration is directly
proportional to the total amount of ground water that must be
processed. Typical, this total quantity of water is expressed
as the number of volumes of contaminated ground water that must
be removed to restore ground-water quality. For example, the
amount of contaminated ground water at Ambrosia Lake is 650
million gallons (Mgal). If the total amount of ground water to
be processed is five volumes, the total amount is 3250 Mgal.
6-1
-------
Table 6.1 Aquifer Restoration Cost Estimates^9)
Site
Ambrosia Lake
Canonsburg
Durango
Amount of
Contaminated
Water
(106 gal)
650
100
500
Pumping
Cost
(1Q6 $)
Install Operate
Trenching
Cost
(1Q6 $)
2.6
0.41
2.1
Treatment°
Cost
(106 $)
Install Operate
0.7
0.11
.57
2.7
.42
2.3
Containment
Cost
(1Q6 $)
1.4(0
Grand Junction
Gunnison
Lakeview
700
2000
3000
2.8
4.1
8.4
12.2
2.9
.76
2.1
3.1
3.0
8.5
12.3
Mexican Hat 90
Monument Valley 3000
Riverton 1000
0.13
4.1
0.39
12.2
4.0
0.1
3.1
1.
0.4
12.3
4.2
Salt Lake City
Shiprock
Tuba City
1600
1250
1250
1.7
5.2
6.5
5.0
1.7
1.3
1.3
6.8
5.2
5.2
(a) Cost estimates are for processing five volumes of contaminated water over 15 years.
Unit costs are $15/sq. ft. for containment, $l,000./Mgal for pumping, $750./Mgal
for trenching and $950./Mgal for treatment.
(b) Assumes all water is treated. These costs may be much less for some sites if effluent
limitations guidelines are met for direct discharges to rivers, or if land disposal is
feasible.
(c) Containment area is 62,500 sq. ft.
(d) Containment area is 35,000 sq. ft.
6-2
-------
Estimating the number of volumes to be extracted is
uncertain on a generic basis. Restoration is greatly dependent
on the chemical characteristics of the aquifer rock which can be
expected to vary widely among sites. In a review of in situ
uranium mining at eight sites (NUREG86), considerable
variability was found in the number of volumes needed to
significantly reduce hazardous constituents in the ground
water. Restoration of the ground water at these sites was
complicated due to the processing solvent (lixiviant) that was
used to dissolve the uranium. An important finding was that,
for those cases where significant restoration was achieved,
almost all the cleanup occurred in the first few volumes removed.
Based on the discussion in Chapter 5 and current DOE
practice, a value of five volumes of contaminated ground water
is selected as the best quantity for estimating costs of
restoration. Selective chemistry may be used at some sites to
enhance restoration, as well as injection of treated (clean)
water to flush (sweep) contaminants from the aquifer. Such
actions are site specific and not amenable to assessment in this
generic analysis.
6.3 Treatment of Contaminated Ground Water
Treatment costs vary from $500.00 to $1,400.00 per Mgal
treated (See Table 5.1). Since seven treatment methods are
available for application at any particular site, it appears
likely that the midpoint of the cost range can be achieved when
averaged over all sites. Therefore, the midpoint value of
$950.00 per Mgal of water treated is selected for use in this
assessment.
6.4 Total Estimated Cost
The estimated cost of ground-water restoration for the 12
sites studied to date is shown in Table 6.1. Pumping costs and
treatment costs include operating costs which are greater than
capital (installation) costs. Therefore, it is necessary to
discount the operating costs to obtain the total cost estimate.
Also, the total cost for the 12 sites are doubled to develop the
estimate for 24 sites. Operating costs are discounted at both
5% and 10% for an operating period of 15 years to estimate
present worth costs in 1987 dollars. At a 5% discount rate the
total estimated cost for restoration of ground water at all 24
sites is $200 million. At a 10% discount rate the total
estimated cost for restoration of ground water at all 24 sites
is $150 million.
6-3
-------
The only reasonable method to estimate total costs is based
on the number of sites since there is no relationship between
the quantity of tailings at a site and the amount of
contaminated ground water at the same site. For example, one of
the largest piles is at Ambrosia Lake (2.6 million tons) which
has an estimated 650 Mgal of contaminated ground water, as
compared to one of the smallest piles at Lakeview (0.13 million
tons) which has an estimated 3000 Mgal of contaminated ground
water.
Restoration of ground-water quality will probably not be
needed at all sites. Based on preliminary data, it is estimated
that about one-third of the sites may qualify for exemption
from restoration because the ground water is Class III or will
be cleansed by natural processes within 100 years. This
estimate is made only for purposes of predicting reasonable
costs. Decisions on exemption from cleanup must be made for
each site by DOE, NRC, and the State or Tribe in accordance with
EPA standards. Reducing the number of sites requiring ground
water cleanup by one-third reduces the cost estimate to about
$130 million using a 5% discount rate or to about $100 million
using a 10% discount rate.
Using a combination of cleanup and institutional control
will also reduce costs. In this instance, partial cleanup,
which appears to be most efficient (see Section 6.2), is
performed to reduce contamination to levels that will be
cleansed by natural processes within the institutional period
limit. This can significantly reduce costs by reducing the
amount of water requiring processing to perhaps two or three
times the contaminated volume (rather than five times). The
implementation of institutional controls is not costly.
Costs could also be reduced if permission could be obtained
to discharge contaminated ground water to rivers or to land
treatment (land farming) facilities (e.g., Christmas tree farm),
rather than treat it. For example, if the uranium concentration
is less than 2 mg per liter, which is the effluent limitations
guidelines for the discharge of waste water from uranium mines
(40 CFR 440), and if all other numerical limits in the
guidelines and BADT requirements are met, it appears it may be
possible to discharge the contaminated water to a river.
Likewise, it may be possible to discharge contaminated ground
water to land treatment facilities provided that the
requirements of 40 CFR 268 are met. However, these
possibilities are site specific to the extent that cost cannot
be estimated on a generic basis.
6-4
-------
6.5 References
NUREG-86 Nuclear Regulatory Commission, "An Analysis of
Excursions at Selected In Situ Uranium Mines in
Wyoming and Texas," NUREG/CR-3967 (ORNL/TM-9956),
1986.
6-5
-------
CHAPTER 7
OTHER CONSIDERATIONS
7.1 Concentration Limits for Molybdenum, Uranium, Radium and
Nitrates
Molybdenum, uranium, radium and nitrates have been found in
tailings and in ground water that is contaminated by tailings.
While these substances have not been listed as hazardous under
the Resource Conservation and Recovery Act (RCRA), which amended
the Solid Waste Disposal Act (SWDA), they have been identified
as hazardous or controlled in other EPA rules using different
authorities. However, quantitative limits that are useful for
this rulemaking have not, as yet, been determined for uranium
and molybdenum. The proposed concentration limits for each of
these four substances are discussed in this section.
7.1.1 Molybdenum
Molybdenum was added to the hazardous constituents for the
licensed tailings since it was found in high concentrations at
some sites and had caused molybdenosis in cattle (48FR45926,
Do72). No concentration limit was established at that time,
however, because only sparse data were available on human
toxicity. Listing molybdenum, but not issuing a concentration
limit, means it must be controlled to background levels, to be
consistent with RCRA standards.
A concentration limit of 50 ppb was proposed for molybdenum
in the proposed standards for inactive tailings (46FR2556).
This proposed groundwater standard was not promulgated, however,
because as stated in the Federal Register notice, "We do not
believe that the existing evidence indicates that ground water
contamination from inactive mill tailings is or will be a matter
of regulatory concern" (48FR590). The Court remanded this to
the Agency in 1985.
The Agency has proposed National Primary Drinking Water
Regulations for Inorganic Chemicals, among others (50FR46936).
While the Agency decided not to propose a Recommended Maximum
Concentration Limit (RMCL) [This is now being called a Maximum
Concentration Limit Goal (MCLG).] for molybdenum because of
inadequate data on toxicity of the compound, a provisional
adjusted acceptable daily intake (AADI) was determined. This
provisional AADI was based upon an epidemiological study in
which only one dose was examined and no effects were noted.
7-1
-------
The Agency asked for comments on the question, "Should a Health
Advisory be developed for molybdenum or is there sufficient
health effects information upon which to base an RMCL?" While
the Agency has not made a final decision on molybdenum, it
appears unlikely that a Health Advisory will be issued for
molybdenum based on the NAS consideration (NAS80) that
molybdenum in drinking water, except from highly contaminated
sources (molybdenum mining waste water), is not likely to
constitute a significant portion of the total human daily intake
of the element.
An analysis of toxic substances in tailings was included in
the Final EIS for Remedial Action Standards for Inactive Uranium
Processing Sites (EPA82), Appendix C. This analysis included
consideration of molybdenum in tailings and of molybdenum
toxicity in humans, livestock, and crops.
Molybdenum in tailings is found at levels greater than 100
times its levels in typical or local soils. Uranium, selenium,
arsenic, and vanadium are the only other metallic elements found
at similarly high levels. However, data show wide variations of
element concentrations among different piles. The ratio of an
element's concentration in tailings to that in the soil
surrounding the tailings is a measure of both its potential
hazard and its potential for contaminating ground water.
Molybdenum is essential in trace quantities for human
nutrition. There are no data for acute toxicity of molybdenum
following ingestion by humans, but the animal data (Ve78) show
that toxicity results from intakes of around hundreds of
milligrams per kilogram of body weight.
Chronic toxicity symptoms have been reported in 18 percent
to 31 percent of a group of Armenian adults who consumed 10 to
15 milligrams of molybdenum per day and in 1 percent to 4
percent of a group consuming 1 to 2 milligrams of molybdenum per
day (Cha79), (NAS80). Clinical signs of the toxicity were a
high incidence of a gout-like disease with arthralgia and joint
deformities, and increased urinary excretion of copper and uric
acid. Increased urinary copper excretion has been observed in
persons who consumed 0.5 to 1.5 milligrams of molybdenum per day
and in persons drinking water containing 0.15 to 0.20 ppm of
molybdenum but not in persons drinking water containing up to
0.05 ppm of molybdenum (Cha79). The significance of the
increased copper excretion is not known. Recent reports have
associated molybdenum deficiency and esophageal cancer
(Lu80a,b). Until these reports are confirmed and evaluated, the
minimum molybdenum requirements are uncertain.
7-2
-------
The ratio of toxic intake to the recommended daily
allowance for humans is narrow for molybdenum, ranging from 10
to 40 (NAS80). Using the NAS80 value for Adequate and Safe
Daily Intake of 0.15 to 0.50 mg and this ratio leads to an
estimated potentially toxic daily intake of 2 to 20 mg of
molybdenum,
In livestock, estimates of molybdenum concentrations
leading to toxicity were made for both ruminants and
nonruminants. The most critical receptor for molybdenum in the
water pathway was dairy cattle, because of the large water
consumption of lactating cows. The estimated concentration of
molybdenum in water that is potentially toxic to dairy cattle is
0.51 to 2.6 ppm (EPA82). This led to a recommended maximum
concentration of molybdenum in water of 0.05 ppm (EPA82).
In crops, estimates were made of molybdenum concentrations
in irrigation water that might be toxic to agricultural crops
grown using such water. Based on an NAS publication (NAS72),
irrigation water at 1 ppm molybdenum could be immediately toxic
to crops if the irrigation water is applied at 3-acre foot per
acre per year (8.13 Ibs of molybdenum per acre per year).
7.1.2 Uranium
The National Interim Primary Drinking Water Regulation
(40CFR141, EPA76) provide no maximum contaminant level (MCL) for
uranium. In fact, uranium along with radon is explicitly
excluded from the MCL for gross alpha particle activity
(40CFR141) which is 15 pCi per liter. These were excluded
because data were inadequate to determine if there was a need
for such regulations (i.e., the levels of uranium and radon in
water were not well-known) and the cost of removal of uranium
and radon from drinking water was not established. The Agency
has issued an advance notice of proposed rulemaking (51FR34836)
stating that MCLGs and MCLs are being considered for radium-226,
-228, natural uranium, radon, gross alpha, and gross beta and
photon emitters.
The standard for uranium in ground water proposed in this
rulemaking is based on allowing the same level of risk for
uranium as for radium. The risk from radium in drinking water
at the MCL (5pCi/l) is 0.7 to 3 cancers per year per million.
The annual limit on intake (ALI) published by the ICRP (ICRP78)
for radium-226 is 7xl04Bq (2xl06pCi). The ALI for
uranium-234 in soluble form (f^ = 0.05) is 4xl05Bq
) and is the limiting ALI for naturally occurring
7-3
-------
uranium nuclides. The ratio of ALIs (uranium-234 to radium-226)
is then 6 leading to the proposed standard of 30pCi/l. Since
the ALI for uranium-234 is limiting, the combined limit for
uranium-238 plus uranium-234 is the same. Uranium-235
constitutes only about 2% of the total uranium activity in
natural uranium and can be ignored in these calculations.
7.1.3 Radium
Radium is present in mill tailings at levels in the
hundreds of pCi per gram range and has been found in elevated
concentrations in ground water near tailings sites. The
National Interim Primary Drinking Water Regulation for radium is
5 PCi per liter combined radium-226 and radium-228. Since the
proposed standards are required by UMTRCA to be consistent with
RCRA standards and since RCRA standards have adopted drinking
water regulations as standards for ground water, the same
procedure is used in this rulemaking. Thus, the proposed
standard for radium is 5 pCi per liter combined radium-226 and
radium-228 .
7.1.4 Nitrates
Nitrates have been found in elevated concentrations in
ground water near tailings piles. The National Interim Primary
Drinking Water Regulation for nitrates is 10 mg per liter as
nitrogen. Using the same rationale as above for radium, the
proposed standard for nitrates is 10 mg per liter as nitrogen.
7-4
-------
7.2 Institutional Control
The Agency has been considering institutional control for
over ten years. Public workshops and a public forum were
conducted in 1977 and 1978 to develop insight for the objectives
of radioactive waste disposal (EPA77a, EPA77b, EPA78). These
efforts resulted in 1978 with the publication of proposed
Criteria for Radioactive Wastes: Recommendations for Federal
Radiation Guidance (43 F.R. 53262). The subject of
institutional control was a major factor in these
recommendations:
"Proposed Criterion No. 2. The fundamental goal for
controlling any type of radioactive waste should be complete
isolation over its hazardous lifetime. Controls which are based
on institutional functions should not be relied upon for longer
than 100 years to provide such isolation; radioactive wastes
with a hazardous lifetime longer than 100 years should be
controlled by as many engineered and natural barriers as are
necessary." And,
"Proposed Criterion No. 6. Certain additional procedures
and techniques should also be applied to waste disposal systems
which otherwise satisfy these criteria if use of these
additional procedures and techniques provide a net improvement
in environmental and public health protection. Among these
are: a. Procedures or techniques designed to enhance the
retrievability of the waste; and b. Passive methods of
communicating to future people the potential hazards which could
result from an accidental or intentional disturbance of disposed
radioactive wastes."
These proposed criteria were further discussed:
"Issue No. 2. Control of Radioactive waste. The
management of radioactive wastes represents potential exposure
of individuals and populations and the possible contamination of
the general environment. These potential impacts require
definitive controls to be established. Further, because of the
trustee responsibility each generation has to succeeding ones,
contamination of the general environment should be avoided
regardless of whether humans will actually contact the waste
directly. It is important to prevent both human and
environmental adverse impacts. Therefore, the fundamental goal
for controlling any type of radioactive waste should be complete
isolation over its hazardous lifetime.
7-5
-------
"Controls for radioactive wastes are of three general types
Engineered barriers, natural barriers, and institutional
mechanisms. Engineered barriers such as containers or
structures generally can be considered only as interim measures
for containment, despite the fact that some structures have
survived intact through the ages. Stable geologic media are an
example of natural barriers. Institutional controls are those
which depend on some social order to prevent humans from coming
in contact with wastes, such as controlling site boundaries,
guarding a structure, land use policies, record-keeping,
monitoring, etc.
"It generally is accepted that long-term isolation should
depend on stable natural barriers. Institutional mechanisms,
which are essential in the early stages of management of any
waste, are short-term processes because of practical
limitations. Institutional means can be very effective in
isolating radioactive wastes from humans if they can be
maintained. Since society's basic structure and concern about
waste may change, it is reasonable to rely on such controls for
only limited periods.
"The choice of a time period for relying on institutional
control is completely a matter of judgment, but is basic to a
determination of when use of such controls is proper. During
the developmental stages of this criteria document, it was
proposed that 100 years should be the maximum time period for
such controls to be depended upon with any degree of assurance.
The public forum participants recommended deleting the time
period because it appeared to be arbitrary; however, they left
the issue unaddressed in any other form.
"Because there are a number of current mechanisms for
disposing of various types of wastes which are based on
institutional care, the Agency believes that guidance is
required to assure that institutional controls are relied upon
only to the extent they are appropriate. There are numerous
types of radioactive wastes of such hazard potential that they
will require the adoption of stricter control methods than
currently practiced and will require the development of new
disposal technologies which will assure better isolation [than]
that afforded by institutional control mechanisms. For this
reason, when disposal decisions are made they should recognize
that institutional controls are only of limited use, and if the
wastes will be hazardous longer than 100 years, other means of
control will need to be found.
7-6
-------
"This means that in selecting control options for wastes
whose hazards extend beyond 100 years decisions makers cannot
rely on restrictions on customary uses of land and of ground or
surface waters. This does not mean that institutional controls
are required for 100 years, or that they must stop at that point
if society can still maintain them; only that people making the
initial disposal decision should not plan on their use to
maintain protection beyond 100 years. The judgment that 100
years is the most appropriate time interval will be further
examined throughout the public comment period."
"Issue No. 6 Supplementary Protection Goals. A number of
other subjects pertinent to protection of the public from
radioactive wastes were discussed in the development of the
criteria. Among these, most attention centered on monitoring,
provision of retrievability, and passive communication of the
nature of the possible hazard to future generations. In
general, it was determined that, while each has positive aspects
for control of radiological hazards, their application might
undermine the goal of providing permanent isolation for wastes.
It is difficult to maintain retrievability or conduct a
monitoring program without compromising the ability to provide
isolation. Furthermore, in many disposal situations which will
satisfy the five criteria discussed above, the residual risk
will mainly be attributable to potential failure mechanisms
involving eventual intrusion by humans. Passive methods of
communicating the hazard, such as markers which call attention
to the waste, may sometimes be judged to provide a net reduction
of risk. Other passive methods, such as creating records
describing the waste, or setting aside of the land title to the
disposal site, have value in reducing the likelihood of
intrusion for some limited time.
"An example of a circumstance where land title transfer is
reasonable is a current site that has been in use for some time
where optimal environmental isolation is no longer a practicable
alternative, such as an abandoned mill tailings site, a nuclear
test facility site, etc. In these cases, Federal ownership of
the land beyond the normal period of institutional control would
be reasonable to minimize potential intrusion. Such decisions
should be made on a case-by-case basis and provision for
specifically treating such exceptions should be addressed in
standards and regulations which are promulgated for these types
of wastes.
7-7
-------
"It is not appropriate to depend upon methods such as these
or other similar ones for long-term control; nonetheless, when
such methods would enhance overall protection from wastes, it is
prudent to use them. This is particularly the case for
retrievability and passive communication. Monitoring was judged
by the Public Forum participants to be generally a part of early
institutional controls prior to completion of disposal, and thus
it is not included in the criterion for supplementary controls."
While these criteria were never enacted in final form, they
served as the basis for the assurance requirements (40 CFR
191.14) which the Agency issued as final standards in 1985:
Environmental Standards for the Management and Disposal of Spent
Nuclear Fuel, High-Level and Transuranic Radioactive Wastes 50
F.R. 38066. These standards culminated the above consideration
of institutional control in this context. Specifically:
40 CFR 191.14 (a) Active institutional controls over
disposal sites should be maintained for as long a
period of time as is practicable after disposal;
however, performance assessments that assess isolation
of the wastes from the accessible environment shall
not consider any contributions from active
institutional controls for more than 100 years after
disposal.
(b) Disposal systems shall be monitored after disposal
to detect substantial and detrimental deviations from
expected performance. This monitoring shall be done
with techniques that do not jeopardize the isolation
of the wastes and shall be conducted until there are
no significant concerns to be addressed by further
monitoring.
(c) Disposal sites shall be designated by the most
permanent markers, records, and other passive
institutional controls practicable to indicate the
dangers of the wastes and their location.
Where the following terms are defined as:
40 CFR 191.12 (a) "Disposal system" means any combination
of engineered and natural barriers that isolate spent
nuclear fuel or radioactive waste after disposal.
7-8
-------
(d) "Barrier" means any material or structure that
prevents or substantially delays movement of water or
radionuclides toward the accessible environment. For
example, a barrier may be a geologic structure, a
canister, a waste form with physical and chemical
characteristics that significantly decrease the
mobility of radionuclides, or a material placed over
and around waste, provided that the material or
structure substantially delays movement of water or
radionuclides.
(e) "Passive institutional control"' means: (1)
Permanent markers placed at a disposal site, (2)
public records and archives, (3) government ownership
and regulations regarding land or resource use, and
(4) other methods of preserving knowledge about the
location, design, and contents of a disposal system.
(f) "Active institutional control" means: (1)
Controlling access to a disposal site by any means
other than passive institutional controls; (2)
performing maintenance operations or remedial actions
at a site, (3) controlling or cleaning up releases
from a site, or (4) monitoring parameters related to
disposal system performance.
And the following guidance for implementation is given:
40 CFR 191 Appendix B Institutional Controls. To
comply with section 191.14(a), the implementing
agency will assume that none of the active
institutional controls prevent or reduce
radionuclide releases for more than 100 years
after disposal. However, the Federal Government
is committed to retaining ownership of all
disposal sites for spent nuclear fuel and
high-level and transuranic radioactive wastes and
will establish appropriate markers and records,
consistent with section 191.14(c). The Agency
assumes that, as long as such passive
institutional controls endure and are understood,
they: (1) can be effective in deterring
systematic or persistent exploitation of these
disposal sites; and (2) can reduce the likelihood
of inadvertent, intermittent human intrusion to a
degree to be determined by the implementing
7-9
-------
agency. However, the Agency believes that passive institutional
controls can never be assumed to eliminate the chance of
inadvertent and intermittent human intrusion into these disposal
sites.
The statement of considerations for this regulation (50
F.R. 38066) includes the following discussion:
"Approach Toward Institutional Controls. The Agency
particularly sought comment on its proposed approach to reliance
on institutional controls. The proposed rule limited reliance
on 'active institutional controls' (such as controlling access
to a disposal site/ performing maintenance operations, or
cleaning up releases) to a reasonable period of time after
disposal, described as on the order of a 'few hundred years.'
On the other hand, 'passive institutional controls' (such as
permanent markers, records, archives, and other methods of
preserving knowledge) were considered to be at least partially
effective for a longer period of time.
"Few commenters argued with the distinction between active
and passive institutional controls, or with the amount of
reliance the proposed rule envisioned for passive controls.
However, many commenters felt that 'a few hundred years' was too
long a period to count on active controls. Accordingly, the
final rule limits reliance on active institutional controls to
no more than 100 years after disposal. This was the time period
the Agency considered in criteria for radioactive waste disposal
that were proposed for public comment in 1978 (43 F.R. 53262), a
period that was generally supported by the commenters on that
proposal. After this time, no contribution from any of the
active institutional controls can be projected to prevent or
limit potential releases of waste from a disposal system.
"The concept of passive institutional controls has now been
incorporated into the definition of 'controlled area' that is
used to establish one of the boundaries for applicability of the
containment requirements and the individual protection
requirements in the final rule. Because the assumptions made
about the effectiveness of passive institutional controls can
strongly affect implementation of the containment requirements,
the Agency's intent has been elaborated in the "guidance for
implementation" section. The Federal Government is committed to
retaining control over disposal sites for these wastes as long
as possible. Accordingly (and in compliance with one of the
assurance requirements), an extensive system of explanatory
markers and records will be instituted to warn future
7-10
-------
generations about the location and dangers of these wastes.
These passive controls have not been assumed to prevent all
possibilities of inadvertent human intrusion, because there will
always be a realistic chance that some individuals will over
look or misunderstand tjie markers and records. (For example,
exploratory drilling operations occasionally intrude into areas
that clearly would have been .avoided if existing information had
been obtained and properly evaluated.) However, the Agency
assumed that society in general will retain knowledge about
these wastes and that future societies should be able to deter
systematic or persistent exploitation of a disposal site.
"The Agency also assumed that passive institutional
controls should reduce the chance of inadvertent intrusion
compared to the likelihood if no markers and records were in
place. Specific judgments about the chances and consequences of
intrusion should be made by the implementing agencies when more
information about particular disposal sites and passive control
systems is available. The parameters described in the "guidance
for implementation" represent the most severe assumptions that
the Agency believed were reasonable to use in its analyses to
evaluate the feasibility of compliance with this rule (analyses
that are summarized in the BID). The implementing agencies are
free to use other assumption if they develop information
considered adequate to support those judgments.
"The role envisioned for institutional controls in this
rulemaking has been adapted from the general approach the Agency
has followed in its activities involving disposal of radioactive
wastes since the initial public workshops conducted in 1977 and
1978. The Agency's overall objective has been to protect public
health and the environment from disposal of radioactive wastes
without relying upon institutional controls for extended periods
of time—because such controls do not appear to be reliable
enough over the very long periods that these wastes remain
dangerous. Instead the Agency has pursued standards that call
for isolation of the wastes through the physical characteristics
of disposal system siting and design, rather than through
continuing maintenance and surveillance. The principle was
enunciated in the general criteria published for public comment
in 1978 (43 F.R. 53262), and it has been incorporated into the
Agency's standards for disposal of uranium mill tailings (48
F.R. 590, 48 F.R. 45926).
"This approach has been tailored to fit two circumstances
associated with mined geologic repositories. First, 40 CFR Part
191 places containment requirements on a broad range of
7-11
-------
potential unplanned releases as well as the expected behavior of
the disposal system. Therefore, determining compliance with the
standards involves performance assessments that consider the
probabilities and consequences of a variety of disruptive
events, including potential human intrusion. Not allowing
passive institutional controls to be taken into account to some
degree when estimating the consequences of inadvertent human
intrusion could lead to less protective geologic media being
selected for repository sites. The Agency's analyses indicate
that repositories in salt formations have particularly good
capabilities to isolate the wastes from flowing groundwater and,
hence, the accessible environment. However, salt formations are
also relatively easy to mine and are often associated with other
types of resources. If performance assessments had to assume
that future societies will have no way to ever recognize and
limit the consequences of inadvertent intrusion (from solution
mining of salt, for example), the scenarios that would have to
be studied would be more likely to eliminate salt media from
consideration than other rock-types. Yet this could rule out
repositories that may provide the best isolation, compared to
other alternatives, if less pessimistic assumptions about
survival of knowledge were made.
"The second circumstance that the Agency considered in
evaluating the approach towards institutional controls taken in
this rule is the fact that the mined geologic repositories
planned for disposal of the materials covered by 40 CFR Part 191
are different from the disposal systems envisioned for any other
type of waste. The types of inadvertent human activities that
could lead to significant radiation exposures or releases of
material from geologic repositories appear to call for much more
intensive and organized effort than those which could cause
problems at, for example, an unattended surface disposal site.
It appears reasonable to assume that information regarding the
disposal system is more likely to reach (and presumably deter)
people undertaking such organized efforts than it is to inform
individuals involved in mundane activities.
"These considerations led the Agency to conclude that a
limited role for passive institutional controls would be
appropriate when projecting the long-term performance of mined
geologic repositories to judge compliance with these standards."
7-12
-------
The Agency is continuing its consideration of institutional
control with emphasis on its effectiveness. There is a need for
guidance on the role for institutional control in developing
corrective action policies for Subtitles C and D under the
Resource Conservation and Recovery Act (RCRA), in designing the
alternate concentration limit (ACL) program under RCRA, and in
developing policies and achieving consistency for Superfund,
especially in view of the Superfund Amendments and
Reauthorization Act of 1986 (SARA).
Institutional controls can be ranked in terms of their
effectiveness although it must be recognized that such ordering
is not objective. There are many shifting perceptions about the
effectiveness of each control, most of which are based on
societal behavior. Nevertheless, the following ranking of
institutional controls in roughly decreasing order of
reliability may be useful in a broad, albeit arbitrary, context:
Monument (marble, granite, etc.)
Security program (guards and fences)
Government ownership
Government controlled easements on property
adjacent to government-owned property
Restrictive covenant (deed restriction)
Deed notice
Professional licensing (licensing of well
drillers)
Permitting programs (well construction
permits)
Environmental standards (for well
construction and location)
Water quality testing
Zoning (regulation of new development and
property transactions)
Health advisories
7-13
-------
The institutional controls with the greatest effectiveness
are permanent and attention-gathering monuments, a security
program involving guards, fences, etc., and government ownership.
The second group involves land records and includes easements,
deed restrictions, and deed notices. This second group is
considered more effective than the third group since it involves
less human activity and what human activity it does entail is
primarily performed early (soon after a decision is made to use
institutional controls). The third group includes
regulatory/licensing actions similar to those applied to
regulated operating activities. This third group involves more
human activity than the second group. The fourth group involves
a variety of general controls which are considered the least
effective of this list.
There are three important points evident in this ranking.
First, some of the institutional controls are active in that
continuing actions are required by persons and some are passive
in that no continuing actions are required by persons. Since
active institutional controls are effective only as long as
persons take action, selecting the period over which they retain
effectiveness is crucial for health and environmental protection.
This timing question became the focus of the Agency's
considerations of institutional control for providing protection
from radioactive waste. There is no general consensus on the
length of time human institutions will remain effective or
reliable to continue such active measures. In this regard,
failure of institutional controls does not necessarily imply a
complete breakdown of societal structure. The more likely
situation would be failure of institutional controls through
program reductions, reorganization, changes in priorities, or
through the failure of special funding mechanisms.
The timing question is most applicable to hazardous
constituents at uranium mill sites since metals are the primary
problem and no radioactive decay or organic decomposition takes
place with metals. Dispersion of the metals in the ground water
or adsorption in the aquifer matrix are the only natural
cleansing processes.
Second, certain active institutional controls can be
effective for as long as they last. A security program, for
example, might well be the best institutional control method
available for a short period. As such, active controls may be
the best solution at a contaminated ground water site, if
predictions of ground water cleansing by natural processes
reliably project decontamination within a period during which
the active institutional controls are highly effective. Another
7-14
-------
benefit of this approach is a reduction in both economic and
environmental costs. An active institutional control solution
is generally less expensive than a restoration program.
Further, less environmental harm results from an active
institutional control than from restoration activities.
Restoration of ground water uses considerable energy and can
contaminate large land areas for impoundments, processing
plants, and associated appurtenances.
Third, institutional controls can be considered voluntary
or involuntary, based on whether people comply with controls on
their own accord or are forced to comply. A permanent marker is
considered a voluntary control since it indicates the presence
of hazardous wastes at a site but does not restrict actions
which might disturb such wastes. A security program is
considered an involuntary control since guards would prevent
people from intruding into such wastes. Controls that prohibit
new well construction or that prevent certain uses of the land
can be voluntary or involuntary depending on the statutory
authorities and implementing philosophy or practice of the local
or state agency.
Institutional controls may be useful when combined with
limited restoration of ground water quality. As discussed in
Chapter 6, most of the decontamination appears to be achieved in
the early stages of ground water pumping. If this initial
efficiency of pumping is found to be the general case or can be
reliably predicted, it may be feasible to combine limited
pumping with institutional controls. This could be especially
attractive if the initial pumping can reduce contaminant
concentrations to levels where natural cleansing will reduce
concentrations to standards levels within the life time of
institutional controls.
Since wide variations exist in contamination and site
characteristics and since local and state laws vary with regards
to institutional control mechanisms, it is difficult to develop
a generally applicable limit for a combined cleanup and
institutional control effort. Nevertheless, it might be
possible to establish a concentration limit at a particular site
that is a few times the MCL and at which consideration of
institutional control is warranted.
7-15
-------
7.3 Groundwater and Precipitation Effects
At some sites ground water intrudes into the tailings; at
least seasonally. Such intrusions will likely lead to
continuing contamination of ground water. Therefore, tailings
having this problem are likely candidates for removal to another
location.
From Table 3-2, it appears that intrusion may be occurring
at three sites: Grand Junction, Riverton, and Salt Lake City.
Because of difficulties in achieving 1,000-year stabilization,
tailings are currently being removed from the Salt Lake City
site and serious consideration is being given to removal of
tailings at the other two sites. The potential ground water
problem, therefore, may further justify removal of tailings at
these sites. It is difficult to evaluate generically a
situation where ground water intrusion is the only reason to
move a pile, although it would be most important to assess the
destabilizing effect such intrusion would leave on long-term
disposal requirements.
At one site, Canonsburg, the average annual precipitation
exceeds the average annual evaporation. This can become a
problem if the net difference (between precipitation and
evaporation) seeps into the tailings instead of running off.
Any such seepage can leach contaminants from the tailings and
carry them into ground water, thus contaminating the ground
water.
To solve this problem the RCRA standards (40 CFR 264.228)
require that the final cover (over surface impoundments
containing hazardous constituents) be designed and constructed
to have among others a permeability less than or equal to the
permeability of any bottom liner system or natural subsoils
present. The standards for licensed uranium tailings (40 CFR
192, Subpart D) for tailings disposal at wet sites (i.e., sites
where precipitation exceeds evaporation) adopt this RCRA
standard. However, at dry sites, the Agency did not adopt this
RCRA standard. The Agency concluded that some seepage of
precipitation into the thick (about three meters) earthen covers
at dry sites would be beneficial in further controlling radon
emissions and that the combination of a thick cover and a
negative precipitation balance would prevent any significant
seepage into tailings, and subsequently into ground water.
7—16
-------
7.5 References
Cha79
Do72
EPA77a
EPA77b
EPA76
EPA78
EPA82
ICRP78
LuSOa
LuSOb
Chappell, W. R., et. al., "Human Health Effects of
Molybdenum in Drinking Water," EPA600/1-79-006, 1979.
Dollahite, J. W., et. al., "Copper Deficiency and
Molybdenosis Intoxication Associated with Grazing Near
a Uranium Mine," The Southwestern Veterinarian, Fall
1972.
Environmental Protection Agency, Proceedings: A
Workshop on Policy and Technical Issue-s Pertinent to
the Development of Environmental Protection Criteria
for Radioactive Wastes, ORP/CSD-77-1, 1977.
Environmental Protection Agency, Proceedings: A
Workshop on Policy and Technical Issues Pertinent to
the Development of Environmental Protection Criteria
for Radioactive Wastes, ORP/CSD-77-2, 1977.
Environmental Protection Agency, "National Interim
Primary Drinking Water Regulations," EPA 570/9-76-003,
1976.
Environmental Protection Agency, Proceedings of a
Public Forum on Environmental Protection Criteria
Radioactive Wastes, ORP/CSD-78-2, 1978.
for
Environmental Protection Agency, "FEIS for Remedial
Action Standards for Inactive Uranium Processing Sites
(40 CFR 192)," EPA 520/4-82-013-1, Oct 82.
International Commission on.Radiological Protection,
"Limits for
Publication
Intakes of Radionuclides by Workers,
30, Pergamon Press, 1979.
ICRP
Luo, X. M., et. al., "Molybdenum and Esophageal Cancer
in China," Southeast-Southwest Regional American
Chemical Society Annual Meeting Abstracts, 40, 1980.
Luo, X. M., et. al., "Preliminary Analysis of the
Distribution of the Esophageal Cancer Mortality
Rates," Geographical Environment and Chemical Elements
in Food and Drinking Water in Anyang Administrative
Region, Honan Province, Chinese J. Oncol. 2:74-80,
1980.
7-17
-------
NAS72
NAS80
Ve78
National Academy of Science, "Water Quality Criteria,
1972," EPA-R3-73-033, NAS, Washington, 1972.
National Academy of Science, "Drinking Water and
Health, Volume 3," NAS, National Academy Press,
Washington, 1980.
Venugopal B. and T. D. Luckey, "Metal Toxicity in
Mammals, Volume 2: Chemical Toxicity of Metals and
Metoloids," Plenum Press, New York, 1978.
EJED 520/1-87-014
Ground water protection
standards for inactive
Due Name/Phone f MCode
.-KT
EJED 520/1-87-014
Ground water protection
standards for inactive
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Pollution Prevention & Toxics (OPPT)
OPPT Library (7407)
401 M Street, SW
Washington, DC 20460
(202) 260-3944
------- |