DRC-2006-001121 - 0901a0688070e122

May 3, 2006
VIA FEDERAL EXPRESS
Mr. Dane L. Finerfrock
Executive Secretary
Utah Radiation Control Board
State of Utah Department of Environmental Quality
168 North 1950 West
Salt Lake City, UT 84114-4850
INTERNATIONAL URANIUM (USA) CORPORATION
Re: Transmittal of 1st Quarter 2006 Chloroform Monitoring Report for the White Mesa
Uranium Mill
Dear Mr. Finerfrock:
Enclosed are two copies of the White Mesa Uranium Mill Chloroform Monitoring Report for the
1st quarter of 2006, as required under State of Utah Notice of Violation and Groundwater
Corrective Action Order UDEQ Docket No. UGQ-20-01.
cc: Ron F. Hochstein
Harold R. Roberts
David Turk
Tel: [phone]
Fax: [phone] I 1050 Seventeenth St., Suite 950
Denver, Colorado, USA 80265 I [e-mail]
www.intluranium.com
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
White Mesa Uranium Mill
Chloroform Monitoring Report
State of Utah
Notice of Violation and Groundwater Corrective Action Order UDEQ
Docket No. UGQ-20-01
1st Quarter (January through March)
2006
Prepared by:
INTERNATIONAL URANIUM (USA) CORPORATION
1050 1 ih Street, Suite 950
Denver CO 80265
April 30, 2006
1. INTRODUCTION
This is the Quarterly Chloroform Monitoring Report, as required under State of Utah
Notice of Violation and Groundwater Corrective Action Order State of Utah Department
of Environmental Quality ("UDEQ") Docket No. UGQ-20-0 1 for the 1st quarter of 2006
(the "Quarter") for International Uranium (USA) Corporation's ("!USA's") White Mesa
Uranium Mill (the "Mill"). This Report also includes the Operations Report for the Long
Tenn Pump Test at MW-4, TW4-19, TW4-15 (MW-26) and TW4-20 for the Quarter.
2. SAMPLING AND MONITORING PLAN
2.1. Description of Monitor Wells Sampled During the Quarter
During the Quarter, the following chloroform contaminant investigation groundwater
samples and measurements were taken:
2.1.1. Groundwater Monitoring
Groundwater Monitoring was performed in all of the chloroform monitoring wells, being
the following wells:
• MW-4 • TW4-11
• TW4-A • TW4-12
• TW4-1 • TW4-13
• TW4-2 • TW4-14
• TW4-3 • TW4-15 (MW-26)
• TW4-4 • TW4-16
• TW4-5 • TW4-17 (MW-32)
• TW4-6 • TW4-18
• TW4-7 • TW4-19
• TW4-8 • TW4-20
• TW4-9 • TW4-21
• TW4-10 • TW4-22
The locations of these wells are indicated on the map attached under Tab A.
Each of these wells was sampled for the following constituents on March 9, 2006:
• Chloroform
• Chloromethane
• Carbon tetrachloride
• Methylene chloride
• Chloride
• The following major ions:
1
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
o Nitrogen, Nitrate + Nitrite as N
2.1.2. Groundwater Head Monitoring
Depth to groundwater was taken in the following wells and/or piezometers during the
Quarter:
a) All of the chloroform contaminant investigation wells listed in paragraph 2.1.1
above on January 17,2006, February 6, 2006 and March 8, 2006;
b) The following point of compliance monitoring wells under the Mill's
Groundwater Discharge Permit ("GWDP") on March 22, 2006: MW-1, MW-2,
MW-3, MW-3A, MW-5, MW-11, MW-12, MW-14, MW-15, MW-17, MW-18,
MW-19, MW-23, MW-24, MW-25, MW-26, MW-27, MW-28, MW-29, MW-
30, MW-31 and MW-32;
c) Piezometers-P-1, P-2, P-3, P-4 and P-5 on March 30, 2006; and
d) Existing monitoring wells-MW-20 and MW-22 on March 29,2006.
In addition, weekly depth to groundwater was taken in MW-4, TW4-15 (MW-26), TW4-
19 and TW4-20, as part of the long term pumping test for MW-4, as discussed in Section
4 below.
Due to a short in one of the instruments, the water level data taken on March 8, 2006 for
TW4-3 and on March 22, 2006 for the following wells is in error: MW-01, MW-03,
MW-05, MW-11, MW-14, MW-15, MW-17, MW-18, MW-19, MW-27 and MW-31.
The instrument has since been repaired.
2.2. Sampling Methodology, Equipment and Decontamination Procedures
The sampling methodology, equipment and decontamination procedures that were
performed for the chloroform contaminant investigation during the Quarter can be
summarized as follows:
2.2.1. Well Purging and Depth to Groundwater
a) A list is gathered of the wells in order of increasing chloroform contamination.
The order for purging is thus established. Mill personnel start purging with all of
the non-detect wells and then move to the more contaminated wells in order of
chloroform contamination, starting with the wells having the lowest chloroform
contamination; and
b) Before leaving the Mill office, the pump and hose are rinsed with de-ionized
("DI") water. Mill personnel then proceed to the first well. Well depth
measurements are taken and the two casing volumes are calculated
(measurements are made using the same instrument used for the monitoring wells
under the Mill's GWDP). The Grundfos pump (a 6 gpm pump) is then lowered
to the bottom of the well. Purging then begins. At the first well, the purge rate is
2
established for the purging event by using a calibrated 5 gallon bucket. After the
evacuation of the first well has been completed, the pump is removed from the
well and placed in DI water and rinsed prior to leaving the well area. After the
rinsing is completed, the well is capped, and Mill personnel then move to the
next well for purging.
2.2.2. Sampling
a) Following the purging of all chloroform investigation wells, the sampling takes
place (usually the next morning). Prior to leaving the Mill office to sample, a
cooler along with blue ice is prepared. The trip blank is also gathered at that time
(the trip blank for these events is provided by the Analytical Laboratory). Once
Mill Personnel arrive at the well sites, labels are filled out for the various samples
to be collected. All personnel involved with the collection of water and samples
are then outfitted with rubber gloves;
b) Mill personnel use a disposable bailer to sample each well. The bailer is attached
to a reel of approximately 150 feet of nylon rope and then lowered into the well.
After coming into contact with the water, the bailer is allowed to sink into the
water in order to fill. Once full, the bailer is reeled up out of the well and the
sample bottles are filled as follows;
(i) First, a set of VOC vials is filled. This set consists of three 40 ml vials
provided by the Analytical Laboratory. The set is not filtered and is
preserved with HCL;
(ii) Second, a 500 ml sample is collected for Nitrates/Nitrites. This sample is
also not filtered and is preserved with H2S04 (the bottle for this set is
also provided by the Analytical Laboratory);
(iii) Third, a 500 ml sample is collected for Chloride. This sample is not
filtered and is not preserved; and
c) After the samples have been collected for a particular well, the bailer is disposed
of and the samples are placed into the cooler that contains blue ice. The well is
then recapped and Mill personnel proceed to the next well.
This manner of sampling has been employed by Mill personnel for chloroform
contaminant investigation sampling, including for split sampling undertaken with UDEQ
personnel, since the inception of the chloroform contaminant investigation.
IUSA is currently in the process of completing a standard operating procedure ("SOP")
and Quality Assurance Plan ("QAP") for sampling under the Mill's GWDP, that will set
out the forgoing procedures in more detail. Upon finalization, this groundwater sampling
SOP and QAP will also be utilized for chloroform contaminant investigation sampling.
3
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
2.3. Field Data Worksheets
Attached under Tab B are copies of all Field Data Worksheets that were completed
during the Quarter for the chloroform contaminant investigation monitoring wells listed
in paragraph 2.1.1 above that were sampled on March 9, 2006, as well as for a field blank
(TW4-60) and a duplicate sample of MW-4 (TW4-63). The Field Data Worksheets are
dated March 8, 2006, which indicates the date on which the wells were purged and the
water levels were taken. The wells were sampled on March 9, 2006. The Field Data
Worksheets for the Quarter do not include all of the information required under the
revised Groundwater Sampling SOP and QAP that are in the process of being developed
under Part 1.H.6 of the Mill's GWDP. Upon approval, the GWDP groundwater sampling
SOP and QAP, which will also be used for the chloroform contaminant investigation
sampling, will include a revised form of Field Data Worksheet that will be employed by
Mill personnel.
2.4. Depth to Groundwater Sheets
Attached under Tab C are copies of the Depth to Water Sheets for the weekly monitoring
of MW-4, TW4-15(MW-26), TW4-19 and TW4-20 as well as the monthly depth to
groundwater monitoring for all of the chloroform contaminant investigation wells.
Monthly depth to groundwater measurements for March 2006 are included on the Field
Data Worksheets included under Tab B.
3. DATA INTERPRETATION
3.1. Interpretation of Groundwater Levels, Gradients and Flow Directions.
3 .1.1. Current Site Groundwater Contour Map
Included under Tab D is a water table contour map, which provides the location of all of
the wells and piezometers listed in item 2.1.2 above for which depth to groundwater was
taken during the Quarter, the groundwater elevation at each such well and piezometer,
measured in feet above mean sea level, and isocontour lines to delineate groundwater
flow directions observed during the Quarter's sampling event. The contour map uses the
March 8, 2006 data for the wells listed in paragraph 2.1.2 (a) above (except TW4-3),
March 22, 2006 data for MW-2, MW-3A, ,MW-12, MW-23, MW-24, MW-25, MW-26,
MW-29, MW-30 and MW-32, March 30, 2006 data for the piezometers listed in
paragraph 2.1.2 (c) above, and March 29, 2005 data for the wells listed in paragraph 2.1.2
(d) above. Due to measurement error, water levels for MW-01, MW-03, MW-05, MW-
11, MW-14, MW-15, MW-17, MW-18, MW-19, MW-27, MW-31 and TW4-3 are from
December, 2005 (see 2.1.2 above).
Also included under Tab D is a groundwater contour map of the portion of the Mill site
where the four chloroform pumping wells are located, with hand-drawn stream tubes, in
order to demonstrate hydraulic capture from the pumping.
4
3.1.2. Comparison of Current Groundwater Contour Maps to Groundwater Contour
Maps for Previous Quarter
The groundwater contour maps for the Mill site for the fourth quarter of 2005, as
submitted with the Chloroform Monitoring Report for the 4th quarter of 2005, dated
January 31,2006, are attached under Tab E.
A comparison of the water table contour maps for the Quarter to the water table contour
map for the previous quarter indicates similar patterns of drawdown related to pumping
of MW-4, TW4-15(MW-26), TW4-19 and TW4-20. Water levels and water level
contours for the rest of the site have not changed significantly since the last quarter.
3.1.3. Hydrographs
Attached under Tab F are hydrographs showing groundwater elevation m each
chloroform contaminant investigation monitor well over time.
Due to a short in one of the instruments, the water level data taken on March 8, 2006 for
TW4-3 is in error (see 2.1.2 above). The hydrograph for TW4-3 includes the incorrect
data point.
3.1.4. Depth to Groundwater Measured and Groundwater Elevation
Attached under Tab G are tables showing depth to groundwater measured and
groundwater elevation over time for each of the wells listed in Section 2.1.2 above.
Due to a short in one of the instruments, the water level data taken on March 8, 2006 for
TW4-3 is in error (see 2.1.2 above). The table for TW4-3 includes the incorrect data
point.
3 .1.5. Evaluation of the Effectiveness of Hydraulic Capture
Perched water containing chloroform has been removed from the subsurface by pumping
MW-4, TW4-19, MW-26 (formerly TW4-15), and TW4-20. The purpose of the pumping
is to reduce total chloroform mass in the perched zone as rapidly as is practical. These
wells were chosen for pumping because 1) they are located in areas of the perched zone
having relatively high permeability and saturated thickness, and 2) high concentrations of
chloroform were detected at these locations. The relatively high transmissivity of the
perched zone in the vicinity of the pumping wells results in the wells having a relatively
high productivity. The combination of relatively high productivity and high chloroform
concentrations allows a high rate of chloroform mass removal.
The impact of pumping these wells is indicated by the water level contour maps attached
under Tabs D and E. Cones of depression have developed in the vicinity of the pumping
wells which continue to remove significant quantities of chloroform from the perched
5
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
zone. The water level contour maps indicate that effective capture of water containing
high chloroform concentrations in the vicinity of the pumping wells is occurring.
Although high chloroform concentrations exist at some locations downgradient of the
pumping wells (for example, near TW4-4), the low permeability of the perched zone at
these locations would prevent significant rates of chloroform mass removal should these
wells be pumped. By pumping at the more productive, upgradient locations, however,
the rate of downgradient chloroform migration will be diminished because of the
reduction in hydraulic gradients, and natural attenuation will be more effective.
3.2. Interpretation of Analytical Results
3 .2 .1. Copy of Laboratory Results
Included under Tab H of this Report are copies of all laboratory analytical results for the
groundwater quality samples collected under the chloroform contaminant investigation
on March 9, 2006, along with the laboratory analytical results for the field blank (TW4-
60), the duplicate sample for MW-4 (TW4-63) and a trip blank.
3.2.2. Electronic Data Files and Format
IUSA has provided to the Executive Secretary an electronic copy of all laboratory results
for groundwater quality monitoring conducted under the chloroform contaminant
investigation during the Quarter, in Comma Separated Values (CSV). A copy of the
transmittal e-mail is included under Tab I.
3.2.3. Current Chloroform Isoconcentration Map
Included under Tab J of this Report is a current chloroform isoconcentration map for the
Mill site.
3.2.4. Data and Graphs Showing Chloroform Concentration Trends
Attached under Tab K is a table summarizing chloroform and nitrate values for each well
over time. TW 4-14 continues to be dry.
Attached under Tab L are graphs showing chloroform concentration trends in each
monitor well over time. As TW 4-14 continues to be dry, a trend graph for that well has
not been included.
3.2.5. Analysis of Analytical Results
Comparing the analytical results to those of the previous quarter, as summarized in the
table included under Tab K, the following observations can be made:
6
a) Chloroform concentrations have increased by more than 20% in the following
wells, compared to last quarter: TW4-A, TW4-6, TW4-16, TW4-21, and TW4-
22;
b) Chloroform concentrations have decreased by more than 20% in the following
wells, compared to last quarter: TW4-7, TW4-10, TW4-19, and TW4-20;
c) Chloroform concentrations have remained within 20% in the following wells
compared to last quarter: MW-4, TW4-1, TW4-2, TW4-4, TW4-5, TW4-15,
andTW4-18;
d) Chloroform concentrations at TW4-8 increased from non-detect to 1.3
micrograms per/liter (J.l g/l); and
e) TW4-3, TW4-9, TW4-12, TW4-13, and TW4-17 (MW-32) remained non-detect.
In addition, the chloroform concentration in recently installed well TW4-20 decreased
from 19,000 J.lg/L in the fourth quarter 2005 to 9200 J.lg/L in the first quarter 2006.
Chloroform concentrations in TW 4-6, which is the most downgradient temporary
perched well, increased from 17 to 31 J.lg/L, consistent with continued, but slow,
migration of chloroform to the south in this area. The rate of chloroform migration in
this area is slow primarily due to low-permeability conditions. The reduction in average
hydraulic gradients due to upgradient pumping also serves to slow the overall rate of
downgradient chloroform migration.
3.3. Quality Assurance Evaluation And Data Validation
Quality assurance evaluation and data validation procedures in effect at the time of
sampling were followed. These involve three basic types of evaluations: field QC
checks; Analytical Laboratory checks; and checks performed by IUSA personnel, as
described below.
3.3.1. Field QC Checks
The following QC samples were generated by Mill personnel and submitted to the
Analytical Laboratory, in order to assess the quality of data resulting from the field
sampling program:
a) One field blank for the March 9, 2006 sampling event (TW4-60); and
b) One duplicate sample of MW-4 for the March 9, 2006 sampling event (TW4-63).
These samples were sent blind to the Analytical Laboratory for analysis for the same
parameters as the other field samples.
In addition, a trip blank was prepared and sent to the Analytical Laboratory for the March
9, 2006 sampling event.
7
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
Rinsate samples were not prepared because a dedicated, single-use disposable bailer was
used to sample each well.
3.3.2. Analytical Laboratory QNQC Procedures
The Analytical Laboratory has provided summary reports of the analytical quality
assurance/quality control (QNQC) measurements necessary to maintain conformance
with NELAC certification and reporting protocol. The Analytical Laboratory QNQC
Summary Report, including copies of the Mill's Chain of Custody and Analytical
Request Record forms, for the March 9, 2006 sampling event, is included under Tab H.
3.3.3. Mill QA Manager Review
The Mill QA Manager, which, for these sampling events was !USA's Vice President and
General Counsel, performed three types of reviews: a determination of whether Mill
sampling personnel followed Mill sampling procedures; a review of the results from the
Field QC Checks; and a review of the Analytical Laboratory QNQC analysis. The
results of the QA Manager's review are discussed below.
a) Adherence to Mill Sampling SOPs
On a review of adherence by Mill personnel to the sampling procedures summarized in
Section 2.2 above, the QA Manager concluded that such procedures had been followed.
b) Results From Field QC Checks
A review of the results of the duplicate sample, TW 4-63 indicates agreement of each
analyte compared to the results for MW-4 and that the contaminant concentrations are
sufficiently accurate. In each case the relative percent difference (RPD) is less than 20%.
A review of the results for field blank (TW 4-60) indicates non-detect for all constituents,
with the exception of a detection of 1.5 J..Lg/L of chloromethane, which is not un-expected.
Small concentrations of chloromethane are typically detected in field blanks generated in
the Mill's laboratory. Similarly the trip blank, initially prepared by the Analytical
Laboratory, indicates non-detect for each VOC analyte, which is to be expected.
c) Review of Analytical Laboratory QA!QC Analysis
The QA Manager reviewed the Analytical Laboratory's QNQC Summary Reports and
made the following conclusions;
(i) Check samples were analyzed for each method used in analyzing the
8
groundwater samples. These methods were:
Parameter Method
Nitrogen, Nitrate + Nitrite as N
Chloroform, carbon tetrachloride,
chloromethane, methylene chloride
Chloride
E353.2
SW8260B
A4500-CL B
(ii) The check samples included at least the following: a method blank, a
laboratory control spike, a matrix spike and a matrix spike duplicate;
(iii) All qualifiers, if any, and the corresponding explanations in the summary
reports are reviewed by the QA Manager. No qualifiers were reported in
the QA/QC Summary Reports for any of the check samples for any of the
analytical methods;
(iv) There were no qualifiers reported in the Laboratory Analytical Reports,
other than an indication that the Reporting Limit was increased due to
sample matrix interference in a number of cases. The sample matrix
interference was due to the dilution required in order to analyze for the
relatively high concentrations of chloroform and/or nitrate & nitrite.
However, because the amounts reported for chloroform and nitrate &
nitrite were well in excess of the increased reporting limit in all samples,
the fact that the reporting limit was increased in those cases had no
practical impact on the analysis of chloroform or nitrate & nitrite. Some
of the results for the other parameters analyzed, however, were non-detect
at the increased Reporting Limits; and
(v) A review of the surrogate spiked samples for each sample also showed
that the Reporting Limit was increased due to sample matrix interference
in those samples where the Reporting Limit for chloroform was
increased, as would be expected.
4. LONG TERM PUMP TEST AT MW-4, TW4-15 (MW-26), TW4-19 AND
TW4-20, OPERATIONS REPORT
4.1. Introduction
As a part of the investigation of chloroform contamination at the Mill site, IUSA has been
conducting a Long Term Pump Test on MW-4, TW4-19, TW4-15 (MW26) and TW4-20.
The purpose of the test is to serve as an interim action that will remove a significant
amount of chloroform-contaminated water while gathering additional data on hydraulic
properties in the area of investigation. The following information documents the
operational activities during the Quarter.
9
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
4.2. Pump Test Data Collection
The long term pump test for MW-4 was started on April 14, 2003, followed by the start
of pumping from TW4-19 on April 30, 2003, from TW4-15 (MW-26) on August 8, 2003
and from TW4-20 on August 4, 2005. Personnel from Hydro Geo Chern, Inc. were on
site to conduct the first phase of the pump test and collect the initial two days of
monitoring data for MW-4. IUSA personnel have gathered subsequent water level and
pumping data.
Analyses of hydraulic parameters and discussions of perched zone hydrogeology near
MW-4 has been provided by Hydro Geo Chern in a separate report, dated November 12,
2001, and in the May 26,2004 Final Report on the Long Term Pumping Test.
Data collected during the Quarter included the following:
a) Measurement of water levels at MW-4, TW4-19, TW4-15 (MW-26), and TW4-
20 on a weekly basis, and at selected temporary wells and permanent monitoring
wells on a monthly basis (See Section 3.1 and Tabs B and C for a discussion of
the water levels);
b) Measurement of pumping history:
(i) pumping rates
(ii) total pumped volume
(iii) operational and non-operational periods;
c) Periodic sampling of pumped water for chloroform and nitrate & nitrite analysis
and other constituents, as discussed in detail in Section 3.2 above.
4.3. Water Level Measurements
Beginning August 16, 2003, the frequency of water level measurements from MW-4,
TW4-15 (MW-26), and TW4-19 was reduced to weekly. From commencement of
pumping TW 4-20, water levels in that well have been measured weekly. Depth to
groundwater in all other chloroform contaminant investigation wells is monitored
monthly. Copies of the weekly Depth to Water monitoring sheets for MW-4, TW4-15
(MW-26), TW4-19 and TW4-20 and the January and February monthly Depth to Water
monitoring sheets for all of the chloroform contaminant investigation wells are included
under Tab C. Monthly depth to water measurements for March are recorded in the Field
Data Worksheets included under Tab B.
10
4.4. Pumping Rates and Volumes
4.4.1. MW-4
Approximately 91,210 gallons of water were pumped from MW-4 during the Quarter.
The average pumping rate from MW -4, when the pump was pumping, was approximately
4.0 gpm throughout the Quarter. The well is not purging continuously, but is on a delay
device. The well purges for a set amount of time and then shuts off to allow the well to
recharge. Water from MW -4 was transferred to the Cell 1 evaporation pond through a
pipeline installed specifically for that purpose. Since commencement of pumping on
April 14, 2003, an estimated total of approximately 992,810 gallons of water have been
purged from MW-4.
4.4.2. TW 4-19
Approximately 327,950 gallons of water were pumped from TW4-19 during the Quarter.
The average pumping rate from TW 4-19, when the pump was pumping, was
approximately 6.0 gpm throughout the Quarter. The pump in this well is operating on a
delay. It pumps for approximately one and a half minutes and then is off for two to three
minutes. Water from TW4-19 was directly transferred to the Cell 1 evaporation pond
through a pipeline installed specifically for that purpose. Since commencement of
pumping on April 30, 2003, an estimated total of approximately 4,350,516 gallons of
water have been purged from TW 4-19.
4.4.3. TW4-15 (MW-26)
Approximately 59,390 gallons of water were pumped from TW4-15 (MW-26) during the
Quarter. The average flow rate from TW4-15, when the pump was pumping, was
approximately 3 gpm throughout the Quarter. The well is not purging continuously, but
is on a delay device. The well now purges for a set amount of time and then shuts off to
allow the well to recharge. The water is directly transferred to the Cell 1 evaporation
pond through a pipeline installed specifically for that purpose. Since commencement of
pumping on August 8, 2003, an estimated total of approximately 766,620 gallons of
water have been purged from TW4-15.
4.4.4. TW4-20
Approximately 99,570 gallons of water were pumped from TW4-20 during the Quarter.
The average flow rate from TW4-20, when the pump was pumping, was approximately
6.5 gpm throughout the Quarter. The well is not purging continuously but is on a delay
device. The well pump is set on a water elevation device. When the water reaches a set
point, the pump turns on until the water level drops to another set point. The water is
directly transferred to the Cell 1 evaporation pond through a pipeline installed
specifically for that purpose. Since commencement of pumping on August 4, 2005, an
11
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
estimated total of approximately 290,550 gallons of water have been purged from TW 4-
20.
4.5. Daily Inspections
IUSA has submitted an Operations and Maintenance Plan, Chloroform Pumping System,
White Mesa Mill, Blanding, Utah, Revision 1.0 to UDEQ for approval. Upon approval of
that plan, the Mill will commence documenting its daily inspections of the operational
status of the chloroform pumping wells on the daily inspection form, an example of the
form of which is attached as Tab M.
4.6. Operational Problems
The following operational problems were encountered during the Quarter:
a) The line from TW4-19 was frozen on January 4, 2006. The pump was not
running. The pump was replaced on January 24, 2006; and
b) During the month of F ebruary, breaker problems were experienced at TW 4-19.
As a result, the pump at TW4-19 did not run the entire month of February.
4.7. Conditions That May Affect Water Levels in Piezometers
No water was added to any of the three wildlife diversion ponds during the Quarter.
4.8. Chloroform Analysis
Monthly chloroform sampling ceased on November 8, 2003. From that time all
chloroform contaminant investigation wells were sampled on a quarterly basis. During
the Quarter, samples from MW-4, TW4-19, TW4-15 (MW-26) and TW4-20 were taken
from a small valve and tee placed in the discharge line downstream from the pump
control valve for each well. The sample results are discussed above in Section 3.2.
5. CONCLUSIONS AND RECOMMENDATIONS
The water level contour map for the Quarter indicates that effective capture of water
containing high chloroform concentrations in the vicinity of the pumping wells is
occurring.
The chloroform concentration in recently installed temporary well TW4-20 decreased
from 19,000 to 9,200 J.Lg/L between the fourth quarter of 2005 and the first quarter of
2006. This fluctuation in concentration is likely related to variations in pumping in this
well and nearby wells, and its location immediately downgradient of the suspected
former office leach field source area. Pumping this well helps to reduce downgradient
chloroform migration by removing chloroform mass and reducing average hydraulic
12
gradients, thereby allowing natural attenuation to be more effective. Continued pumping
of wells that are currently pumping is recommended.
The increase in chloroform concentrations at downgradient well TW 4-6 from 1 7 to
31 J.Lg/L is consistent with continued, but slow, migration of chloroform to the south in
this area. Migration rates in this area are low primarily due to low-permeability
conditions, although the overall rate of chloroform migration is also slowed as a result of
pumping at upgradient locations.
13
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I