DRC-2012-001562 - 0901a068802e22f4

.2912-00 1562
Department of
Environmental Quality
Amanda Smith _
Executive Director
DIVISION OF RADIATION CONTROL
Rusty Lundberg
Director
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State of Utah
GARY R- HERBERT
Govemor
GREG BELL
Lieutenant Govemor
May 30, 2012
CERTIFIED MAIL
(Return Receipt Requested)
Jo Ann Tischler
Director, Compliance and Permitting
Denison Mines (USA) Corp.
1050 Seventeenth St. Suite 950
Denver, Colorado, 80265
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P.OrtlflQrl Coo 1 RE 5/30/2012, NOED& RFI / TR
Jo Ann Tischler
Denison Mines (USA) Corp
fs 1050 Seventeenth ST, STE 950
Denver, CO 80265
City. State, ZIP+4
PS Form 3800. August 2006 See Reverse (or Instructions
Subject: Denison Mines (USA) Corp., January 12, 2012 Southwest Hydrogeology Investigation
Report: DRC NOED and RFI
Dear Ms. Tischler:
The Utah Division of Radiation Control (DRC) has reviewed the Denison Mines (USA) Corp.
(DUSA) document titled "January 12, 2012, Hydrogeology of the Perched Groundwater Zone in
the Area Southwest of the Tailings Cells, Wliite Mesa Uranium Mill Site^^ (Report), which was
prepared by Hydro Geo Chem, hic. (HGC). The Report was required by Part I.H.6 ofthe facility
Ground Water Discharge Permit, Permit No. UGW370004 (Permit).
Notice of Enforcement Discretion
Part I.H.6(a)2. ofthe Permit requires DUSA to:
"fl) Install multiple borings and7or monitoring wells to completely enclose and define both •
2) Piezometers or wells that intercept the shallow aquifer and encounter a saturation
thickness of 5-feet or more. Said wells and piezoT?ieters shall have a tninimum
inside diameter of 3 inches. Tlie Permittee shall complete hydraulic testing of all
such wells and piezometers iti accordance with Part IF.6(c) ofthis Permit. "
Per DRC review of the Report, it was noted that three of the borings, which had a saturated
interval of greater than 5 feet, were abandoned without completion of casings/screens or hydraulic
testing. Specifically, borings DR-02, DR-16 and DR-25 were abandoned in violation of the
Permit Part I.H.6(a)2.
] c)5 North 1950 West • Salt Lake Cit>', UT
Maihng Addre.ss P O Box 144850 • Salt Lake Cit>', UT 84114-4850
Telephone [phone] • Fax [phone] - TDD [phone]
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FYinted on 100",j recvcltd paptr
Jo Ann Tischler
Southwest Investigation
Page 2
DRC is providing enforcement discretion for these violations, based on:
1. DUSA good faith efforts to provide the southwest hydrogeology study and report,
including fieldwork to provide 22 borings used to measure initial water levels, 18 of which
were completed as piezometers for ongoing water level measurements and 13 of which
were used for falling head slug tests to determine hydraulic properties of the Burro Canyon
Aquifer
2. The DUSA agreement to conduct additional borings and install additional piezometers m
the vicinity of and west of abandoned boring DR-02, in order to characterize hydraulic
properties and ground water flow directions in this area as discussed below.
Request for Information
DRC finds that several data gaps exist to comply with the Permit requirements of Part I.H.6 and to
support fmdings in the Report. These data gaps are:
1. The Report does not provide field measured evidence to support a hydraulic divide in the
area of piezometer DR-05 and abandoned borehole DR-02, as required by the Permit
I.H.6.C. Flow path lines as depicted on Figure 12 of the Report west of piezometer DR-05,
which discount westerly flow toward Cottonwood Seep, are not supported with measured
groundwater elevations and plotted contours that extend into this area. The Report data
shows relatively significant saturated thickness, > 10 ft, measured at piezometer DR-05
and boring DR-02 (prior to abandonment), but does not provide field data to determine
how far west the zone of saturation extends or to provide hydrauhc evaluation of that zone.
Additional borings and study are needed to better characterize flow and hydrogeology of
the perched aquifer in the area west of abandoned boring DR-02 (southwest of Westwater
Seep) and to substantiate the statement in the Report that this area is "inadequate as a
potential supply to Cottonwood Seep (p. 19)." (based on water balance results for DR-10
and DR-05 only). Per Figure E.2 of the Report, the Burro Canyon Formation outcrops
continue approximately 0.8 mile west of Westwater Seep (approximately 0.5 miles west of
abandoned bonng DR-02). Additionally, Figure E.2 ofthe report shows a significant area
of slumps and landslides which extend even farther to the west.
2. The Report, Table 3, lists slug test results (K and Ss) for the investigation completed
piezometers. DRC notes that the slug test results for piezometer DR-08 differ by an order
of magmtude between the automatically logged data and the hand collected data. DRC
additionally notes that Table 3 hsts, '"Not Inteipretable'^ as the K value at DR-08 by the
Bouwer-Rice Method using the Hand Collected data. Slug tests at piezometer DR-08 need
to be repeated in order to validate the reported hydraulic conductivity values, and to
substantiate the inclusion of these results in the hydraulic conductivity averages.
3. The Report does not provide evidence to support the claims of a hydrauhc comiection
between Westwater Creek and Cottonwood Seep as required by the Permit Part I.H.6.C
The Report Figure 16, delineates an area which HGC interprets as the likely source of
Jo Ann Tischler
Southwest Investigation
Page 3
Cottonwood Seep based on elevation, however no additional information is provided to
support the hydraulic connection. Such evidence is required to include:
a. Evidence of a confinuous zone of liigher permeability connecfing the likely source
area of Westwater Creek with Cottonwood Seep (e.g. boring logs showing the
coarser grained or sandstone layer),
b. Delineation of stream alluvium deposits within the Cottonwood Creek drainage and
especially within the proposed likely stream segment of Cottonwood Seep (to
understand the actual zone of influence),
c. Average flow in the Westwater Drainage,
d. Evidence that Westwater Creek is a gauiing stream in the segment proposed as a
recharge source to Cottonwood Seep,
d. A detailed evaluation/explanation ofthe hydrauhc mechanism promofing flow into
the hypothesized higlier permeability layer, instead of stream bed flow.
Addifionally, per the Pemiit part I.H.6(g) please provide DRC at least 14 business day notice pnor
to drilling additional borings and/or hydraulic testing of piezometers for the additional required
study in order to provide DRC the opportunity to observe the activities in the field.
Per telephone conversations between DRC and DUSA personnel on May 23, 2012 and
May 24, 2012, DUSA will review the request for information items above, and then arrange a
telephone conference call with DRC to discuss and agree upon specific actions for additional
study. The call will be held within 30 calendar days of DUSA receipt of this letter.
Ifyou have any questions regarding tliis letter please contact Tom Rushing at [phone].
Sincerely,
Rusty Lundberg, Director
RL:TR:tr
F VDUS.-WSouthwest hivestigationVIanuary 12, 2012 HGC Report^SW Investigation 1-12-12 Report - DRC Findings and RFI Letter doc\