DRC-2006-001123 - 0901a0688070e18e

0 IUC
October 31, 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 3nd 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
3nd quarter of 2006, as required under State of Utah Notice of Violation and Groundwater
Corrective Action Order UDEQ Docket No. UGQ-20-01.
Yours truly,
'} /1 :,.?-_ __.,,-"/ ! .. v--0-~~t..__. __
<' ,·
_ .... Steven D. Landau
Manager, Environmental Affairs
cc: Ron F. Hochstein
David C. Frydenlund
David Turk
Tel: [phone]
Fax: [phone] I 1050 Seventeenth St., Suite 950
Denver, Colorado, USA 80265 I [e-mail]
www.intluranium.com
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White Mesa Uranium Mill
Chloroform Monitoring Report
State of Utah
Notice of Violation and Groundwater Corrective Action Order UDEQ
Docket No. UGQ-20-01
3rd Quarter (July through September)
2006
Prepared by:
INTERNATIONAL URANIUM (USA) CORPORATION
· 1050 17th Street, Suite 950
Denver CO 80265
October 30, 2006
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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 3rd quarter of 2006
(the "Quarter") for International Uranium (USA) Corporation's ("IUSA's") White Mesa
Uranium Mill (the "Mill"). This Report also includes the Operations Report for the Long
Term 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 • TW 4-15 (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 July 20, 2006:
• Chloroform
• Chloromethane
• Carbon tetrachloride
• Methylene chloride
• Chloride
• Nitrogen, Nitrate + Nitrite as N
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As UDEQ is aware, IUSA has experienced difficulty in obtaining chloroform samples
from well TW4-14. The difficulty arises from the very limited recovery rate encountered
at that location. More specifically, it is necessary that there be at least 1.5 feet of water
within the well in order to obtain a sample which is not influenced by sedimentation from
the bottom of the well. At the request of UDEQ, the recovery rate from the TW4-14
location has been recently evaluated by bailing and routine water level measurements in
order to determine the necessary time between purging and sample collection. This
evaluative effort was designed to examine a purging schedule for TW4-14 which will
allow enough time to be able to collect a sample for the quarterly sampling round.
Accordingly, on September 21, 2006 the sample technician purged TW4-14 by bailer.
The pre-bailing water level within the well was 91.85 ft below the measuring point.
After bailing, the depth-to-water had dropped 1.65 ft to 93.5 ft below the measuring
point. However, recovery continued to be slow and by October 20, 2006 the water level
had only risen about one foot to 92.55 ft below the measuring point. It is !USA's hope
that the well will rise an additional Vz foot by the time 4th Quarter sampling is completed
next month.
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 July 19,;
b) The following point of compliance monitoring wells under the Mill's
Groundwater Discharge Permit ("GWDP") during the period September 13 to
September 18, 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-3 1 and MW-32;
c) Piezometers-P-1, P-2, P-3, P-4 and P-5 on September 19, 2006; and
d) Existing monitoring wells-MW-20 and MW-22 on September 19, 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.
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
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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
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.
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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 has completed (and transmitted to UDEQ on May 25, 2006) a revised Quality
Assurance Plan ("QAP") for sampling under the Mill's GWDP. The GWDP QAP has
been reviewed by UDEQ and draft (email) comments from DEQ were received by IUSA
on Oct 18, 2006. Subsequent to receipt of UDEQ's comments, IUSA has committed to
respond to these comments by November 20, 2006. The QAP provides a more detailed
presentation of procedures utilized for groundwater sampling activities under the GWDP.
While the water sampling conducted for chloroform investigation purposes is conformant
with the general principles set out in the QAP, it does not conform to all the requirements
in the QAP. Once the GWDP QAP is finalized and approved by UDEQ it will be
evaluated to determine to what extent it should also apply to the chloroform investigation
monitoring.
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 and sampled on July 20, 2006. The Field Data Worksheets for
the Quarter do not include all of the information required under the revised GWDP QAP.
As mentioned above, the GWDP QAP is intended for application to general groundwater
sampling methods and principally those samplings conducted under the GWDP
monitoring program. In the case of chloroform monitoring, well purging prior to
sampling is accomplished by means of a high-rate Grundfos pump which has been
dedicated specifically to the chloroform monitoring program. Due to the high pumping
rate of this pump, field data to determine stable conditions cannot be recorded. Instead,
water samples are collected subsequent to the initial high-rate purging event, and usually
the day after purging. Accordingly, the field data form utilized for groundwater sampling
under the GWDP will be modified for chloroform sampling. The chloroform Worksheet
will exist as a separate document to accommodate this purging and data recordation
difference. As noted above, the GWDP QAP is in the process of review/response under
Part l.H.6 of the Mill's GWDP. Comments from UDEQ have been received and a
response to those comments is forthcoming, including the separation of chloroform
investigation monitoring from the broader GWDP program. Once the GWDP has been
finalized and approved by UDEQ, it will be evaluated to determine to what extent it
should also apply to the chloroform investigation monitoring.
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 July, 2006 are included on the Field
Data Worksheets included under Tab B.
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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
July 19, 2006 data for the wells listed in paragraph 2.1.2 (a) above, September 13 to
September 18 data for the wells listed in paragraph 2.1.2 (b) above, September 19, 2006
data for the piezometers listed in paragraph 2.1.2 (c) above, and September 19, 2006 data
for the wells listed in paragraph 2.1.2 (d) 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
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 second quarter of 2006, as
submitted with the Chloroform Monitoring Report for the second quarter of 2006, dated
July 31, 2006, are attached under Tab E.
A comparison of the water table contour maps for the Quarter to the water table contour
maps 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 site have not changed significantly since the last quarter, except there
was less drawdown in TW4-20 than in the previous quarter. Fluctuations in water levels
in the pumping wells are due in part to fluctuations in pumping conditions just prior to
and at the time the measurements are taken
3.1.3. Hydrographs
Attached under Tab F are hydrographs showing groundwater elevation m each
chloroform contaminant investigation monitor well over time.
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 2.1.1 above.
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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
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. As
noted in Section 3 .1.2, less draw down was measured in TW 4-20 as compared to the
previous quarter. However as defined by drawdowns in nearby, non-pumping wells that
serve as observation wells, and that are not strongly affected by short-term fluctuations in
individual well pumping rates, the combined capture of TW4-19, TW4-20, and MW-26
has not changed significantly since the last quarter.
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 July 20, 2006, along with the laboratory analytical results for 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.
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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. TW4-14 continues to be dry (see the discussion in Section 2.1.1 above)
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:
a) Chloroform concentrations have increased by more than 20% in the following
wells, compared to last quarter: TW4-1, TW4-2, TW4-10, TW4-15 and TW4-22.
b) Chloroform concentrations have decreased by more than 20% in the following
wells, compared to last quarter: TW4-6, TW4-16, and TW4-20;
c) Chloroform concentrations have remained within 20% in the following wells
compared to last quarter: MW-4, TW4-4, TW4-5, TW4-7, TW4-11, TW4-18,
TW4-19, and TW4-2 1;
d) Chloroform concentrations at TW4-8 decreased from 1.0 micrograms per/liter
(11gll) to non-detect; 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 61,000 11g/L in the second quarter 2006 to 5,300 11g/L in the third quarter 2006 and
the concentration in TW4-22 increased from 280 11g1L in the second quarter 2006 to 884
11g/L in the third quarter 2006. Chloroform concentrations in TW4-6, which is the most
downgradient temporary perched well, decreased from 19 toll 11g/L. This is the second
quarter of reductions in concentrations measured in this well. The decreases in
concentration are likely due in part to the reduction in average hydraulic gradients
resulting from upgradient pumping which will slow the rate of chloroform migration.
Chloroform migration rates in this area are also slow due to low permeability conditions.
TW4-14 also continues to be dry.
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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
Field Quality Control samples for the chloroform investigation program consist of a field
duplicate sample, a field blank and a trip blank. These check samples are to be generated
for each quarterly sampling episode. During the 3rd Quarter of 2006 the Mill's
Environmental Technician inadvertently failed to collect/prepare these samples. The
Environmental Technician has been advised of this failure. In order to prevent a
recurrence of this mistake by the Environmental Technician, the Mill's Radiation Safety
Officer (RSO) will personally direct appropriate attention to QC sampling during the next
sampling event and as necessary in connection with subsequent sampling events.
A trip blank was prepared and sent to the Analytical Laboratory for the July 20, 2006
sampling event.
Rinsate samples are not prepared because a dedicated, single-use disposable bailer is used
to sample each well.
3.3.1. Analytical Laboratory QA/QC Procedures
The Analytical Laboratory has provided summary reports of the analytical quality
assurance/quality control (QA/QC) measurements necessary to maintain conformance
with NELAC certification and reporting protocol. The Analytical Laboratory QA/QC
Summary Report, including copies of the Mill's Chain of Custody and Analytical
Request Record forms, for the July 20, 2006 sampling event, are included under Tab H.
3.3.2. Mill QA Manager Review
The Mill QA Manager, which, for these sampling events was IUSA's Manager of
Environmental Affairs, 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 QA/QC 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
with the exception of missing QC check samples indicated above.
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b) Results From Field QC Checks
As stated above, the Mill's Environmental Technician failed to prepare/collect
appropriate duplicate and field blank samples for the 3rd Quarter. A review of the results
of the trip blank did not identify detectable concentrations for measured parameters.
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
Chloroform investigation samples. These methods were:
Parameter
Nitrogen, (Nitrate +Nitrite as N)
Chloroform,
Carbon tetrachloride
Chloromethane
Methylene chloride
Chloride
Method
E353.2
E624
E624
E624
E624
A4500-CL B
(ii) The check samples included at least the following: a method blank, a
laboratory control spike (sample), 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 QNQC 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;
(v) A review of the surrogate spiked samples for methylene chloride in each
sample also showed that the Reporting Limit was increased due to sample
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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 (MW-26) 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.
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 TW 4-19 on April 30, 2003, from TW 4-15 (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.
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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 TW4-20, 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 August and September 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 July are recorded in the Field
Data Worksheets included under Tab B.
4.4. Pumping Rates and Volumes
4.4.1. MW-4
Approximately 99,780 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. At the end of the 3rd Quarter, 2006, and
since commencement of pumping on April 14, 2003, an estimated total of approximately
1,176,850 gallons of water have been purged from MW-4.
4.4.2. TW4-19
Approximately 633,910 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. At the end of the 3rd Quarter,
2006, and since commencement of pumping on April 30, 2003, an estimated total of
approximately 5,433,346 gallons of water have been purged from TW4-19.
4.4.3. TW4-15 (MW-26)
Approximately 32,840 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 1.5 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. At the end of the 3rd
Quarter, 2006, and since commencement of pumping on August 8, 2003, an estimated
total of approximately 845,550 gallons of water have been purged from TW4-15.
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4.4.4. TW4-20
Approximately 80,790 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
6.0 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
estimated total of approximately 382,670 gallons of water have been purged from TW4-
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) At location TW4-15 flow meter problems were experienced in the later part of
July and during August. Several flow meters were replaced in response to
these difficulties. Also during this quarter a power bump occurred due to
installation of equipment in the milling facility (barrel crusher). This resulted
in approximately one week of power loss to the well. It has also been noted
that the pump at this location is experiencing a lessened pumping rate and will
need replacement soon.
b) As was the case for TW4-15, TW4-20 also experienced flow meter problems
in the later part of July and during August. Here too, several flow meters
were replaced in response to the flow meter defects.
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
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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
occurrmg.
The chloroform concentration in recently installed temporary well TW4-20 decreased
from 61,000 to 5,300 flg/L between the second quarter of 2006 and the third 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. The increase in chloroform in TW 4-22 from 280 to
884 flg/L between the second and third quarters of 2006 is also likely related to changes
in nearby pumping rates and its location close to the suspected source area. Regardless of
these measured fluctuations in chloroform concentrations, pumping TW4-20 helps to
reduce downgradient chloroform migration by removing chloroform mass and reducing
average hydraulic gradients, thereby allowing natural attenuation to be more effective.
Continued pumping of wells that are currently pumping is recommended.
The decrease in chloroform concentrations at downgradient well TW 4-6 from 19 to
11 flg/L is consistent with the generally slow migration of chloroform to the south in this
area, and the impact of upgradient pumping. 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. Upgradient
pumping likely contributed to the measured decrease in TW4-6 chloroform
concentrations since the last quarter.
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SECTION
A