DRC-2010-002766 - 0901a0688017a5bf

State of L/tah
(i.ARY R, HERBERT
rMJi'(V7/('r
GREG BELL
Lieuieiiiiiil Cowrnar
Department of
Environmental Quality
Amanilii Smilh
L.\i-<-un\L' Diri-rlor
Dl\' IS ION OF RADI,-\T10N CC.)NTR( )l.
Dnnc L. Fincrlrock
Director
DRC-2010-002766
MEMORANfDUM
9/6)
TO: Loren Morton, Section Manager
FROM: Dean Henderson, Hydrogeologist
DATE: April?, 2010
SUBJECT: Operaiions and Maintenance Plan tor (he Chloroform Investigation
UDEQ Docket No. UGQ-20-OI
White Mesa Uranium Mill, near Blanding, Utah
On May 4, 2009 DUSA submitted Revision 2.0 Operations and Maintenance Plan Chloroform
Pumping System at the White Mesa Uranium Mill (hereafter "Plan"), dated Apnl 30, 2009. The
submitted Plan is in response to a Confirmatory Action Leiter (hereafter ''CAL") issued by DRC
dated April 14,2009.
The CAL required the Plan to be submitted on or before April 30, 2009. The Plan was dated April
30, 2009 and arrived at the Division of Radiation Control (hereafter "DRC") on May 4, 2009.
Although the plan was 4 days late, it is recommended that no enforcement be laken.
REVIEW
The review fonnat will be a statement ofthe DRC CAL item (in italics), followed by a summary
of DUSA actions and DRC response to DUSA actions, culminating in DRC staff conclusions.
CAL Item L
FloM' Meter Readings - To help identify operational problems with the pumping system a flow
merer reading needs to he checked and recorded daily. Please add To the daily inspection
report form, the need to check and record flow meter readings.
DUSA Actions
The maintenance section ofthe Plan states:
"In conjunction with this operational check, the flow meter reading is recorded on a daily basis
I6S North l*)5(i Wcsl • Snll Lakt Cily, UT
Miiiling Addres-?, P,0, Box 144H50»S.ill LukeCii), I IT S4114-4850
Tclephfine(finij536-425lt'F;i,t(80lol3 -XyfH • T,D,D, (801) 5?fj 4414
iiii-ii,.•//•!; innli ii'iy
I'niileilon lUH'.-j rccvticd T'lp^^r
Pase 2
on Daily Inspection Repori. A copy ofthe Daily In.spection Report is included in the Plan and
has a localion where daily flow meter reading can be recorded."
DRC Response
DUSA actions appear lo satisfy CAL Item 1.
CAL Item 2.
Winierizationfor Long-Tenii Operations Section - Please revise such that items il 2), and3)
in fhis section will also apply to all fulure pumpin;^ wells.
DUSA Actions
In item 4 in the winteiization for iong-tenn operations section of the Plan states:
'The protective features, discharge line placement and winter inspections descnbed in items
I), 2) and 3) above will apply to not only the (4) pumping vvells cuiTently in operalion, but will
apply cilso to uny future pumping wells associated with the chloroform pumping system.".
DRC- Response
DUSA aclions for item 4 needs lo be modified wilh the following wording changes (deleted
working shown in strike-out and added wording shown as underlined):
"The protective features, discharge line placement and winter inspections descnbed in items
1), 2) and 3) above will apply to nol only the-f4) (5} pumping wells currently in operation, but
will apply also to any future pumping wells associated with the chloroform pumping system."
CAL Item 3.
Operations Section - Please revise to include:
• Re-identify pumping well 7W4-I5 lo rejlect its new designation as well MW-26, and add
the new pumping well TW4-20.
• Propose for E.xecutive Secretary approval, minimum drawdown elevations for each
pumping well to demonstrate hydraulic capture ofthe chlorofonn plume.
DUSA Actions (response to first DRC bullet)
In the first sentence ofthe operations section, lhe Plan has re-identified well TW4-15 as MW-
26 and DUSA has added the new pumping well TW4-20.
DRC Response first bullet in CAL Item 3
DUSA actions appear to satisfy the first bullet in CAL Item 3
DUSA Actions (response to 2"^^ DRC bullet)
"In order lo determine the appropriate minimum drawdown elevation for each well and to
ensure hydraulic capture of the chloroform plume, an evaluation of the physical and
hydralic characteristics ofeach well was undertaken in April of 2009. Accordingly, the
following informaiion and proposed minimum drawdown elevations resulted from that
effort:
I. Backi^round
Page 3
As discussed above, perched water containing chloroform has been removed from the
subsurface by pumping MW-4, TW4-19, MVV-26, and T\V4-20 (Figure 1). The puqiose
ofthe pumping is to reduce total chloroform mass in the perched zone as rapidly a.s is
Page 2 practical. These wells were chosen for pumping because I) ihey are located in areas of
the perched zone having relatively high permeability and saiuraled thickness, and 2) high
concentrations of chloroform were detected at these locaiions. The relatively high
transmissivity ofthe perched zone in the vicinity ofthe pumping welis results in the wells
having a relatively high productivity. The combination of relatively high productivity
and high chlorofonn concentrations allows a high rale of chlorofomi mass removal.
The impact of pumping these wells since the fourth quarter of 2005 is indicaled by the
waler level contour maps provided in the Quarterly Chlorofonn Monitoring Reports
submiited lo UDHQ. Cones of depression have developed in the vicinily of lhe pumping
wells which have removed significant quanlities of chlorofonn from the perched zone.
The water level contour maps indicate that effective capture of waler containing high
chloroform concentrations in the vicinity of the pumping wells has occurred since the
fourth quarter of 2005. Although the combined capture of MW-4, MW-26. TW4-I9, and
TW4-20 has fluctuated based on lolal extraction rate and other condilions, overall capture
has nol changed significanlly since the fourth quarter of 200.*5.
Allhough high chloroform concentrations e.xist at some locations downgradient ofthe
pumping wells (for example, nearTW4-4). The low permeability ofthe perched zone al
these locaiions would prevent significant rales of chloroform mass removal should these
wells be pumped. By pumping at the more productive, upgradient locaiions, however,
the rate of downgradieni chlorofoim migration will be diminished because of the
reduction in hydraulic gradients, and natural attenuation will be more effective. Pumping
has helped stabilize the chloroform plume. .Although chloroform has been detected at
downgradieni well 7^4-6 since the second quarter of 2005. the plume (defined by
chloroform concenlrations exceeding 70 micrograms per liter [|ig/L]) as nol vet impacted
this well, nor has it impacted other downgradient wells TW4-16 andTW4-23.
2. Quarterly Water Levels
Water level data collected quarteriy and submitted wilh the Chloroform Monitoring
Reports have shown fluctuations in depths to water and water levels at pumping wells
MW-4, MW-26 (TW4-I5), TW4-19, and TW4-20. Pre-pumping depths to water and
waler levels at these wells were approximately 61 feet (ft) and 5562 ft above mean sea
level (amsl) for MW-4: 50 fl and 5576 ft amsi for MW-26: 4S ft and 5583 ft amsl for
TW4-19: and 62 ft and 5568 ft amsl for TW4-20, respectively. During pumping, depths
to waler at MW-4 have fluctuated between approximately 68 and 85 ft and have averaged
75 ft: depths to water al MW-26 (TW4-I5) have tluctuated belween approximaiely 74
and IOI fl and have averaged 81 ft: depths to waler at TW4-19 have fluctuated between
approximately 62 and 96 ft and have averaged 81 ft: and depths to water at TW4-20 have
fluctuated between approximately 66 and 99 ft and have averaged 82 ft. The first quarter.
2008 depth to water of 60.4 ft reported for well TW4-20 represented a non-pumping level
and Is not included in the range nor average provided above. Pre-pumpIng, average, and
ranges in water levels arc summarized in Table 1.
Pa2e 4
3. Proposed Waler Level Targets
Pumping of MW-4, MW-26, TW4-19, and TW4-20 has been shown to have removed
significant quantities of chlorofonn from lhe perched zone and to have helped to stabilize
the plume. The relative stability of the plume is shown in Figure 2. which compares the
extent ofthe plume in the fourth quarter of 2008 with the extent of the plume in the
fourth quarter of 2005. .'\s discussed above, the plume has nol impacted downgradient
wells TW4-6, TW4-16 norTW4-23. Although chlorofoim concentrations at
downgradient well TW4-6 have fluctuated, this well has likely remained outside the
chlorofonn plume due to a combination of 1) slow rales of downgradient chloroform
migration in this area due to low permeability conditions and the effects of upgradient
chlorofoim removal by pumping, and 2) natural attenuation. Chloroform has remained
non detect at downgradient temporary well TW4-23. Both TW4-6 and TW4-23 bound the
chloroform plume to the south.
Because pumping under past conditions has been shown to be effective, continued
pumping sufficient lo mainiain the long term average depths lo water and waler
levels of approximately 75 ft and 5547 ft amsl at lvrW-4; 81 ft and 5544 ft amsl at
MW-26; 81 ft and 555'l ft amsl at TW4-19; and 82 ft and 5547 ft amsi at TW4-20.
respectively, is proposed wiih two constraints. These levels will be maintained by
installing a pump activation probe at the elevation identified.
The ftrsl constraint is that waler levels during pumping al any given time be maintained
wllhln the pumping water level ranges that have been measured in the past (Table 1). The
second constraint is that target averages and ranges be corrected for changes in "regional"
perched zone waier level conditions. The changes in regional conditions will be defined
by waler levels in two groups of non-pumping wells. The ftrst group will consist of
TW4-1, TW4-2, TW4-8, and TW4-11. Changes in the average perched zone water level
defined by waler leve! measurements in this first group of wells will be used lo correct
the water level targets for MW-4. The second group will consist of TW4-10-TW4-16,
TW4-i8, TW4-21, and TW4-22. Changes in the average perched zone water level defined
by water level measurements in this second group wells will be used to correct the water
level targets for MW-26, TW4-19, andTW4-20. Target adjustment will not be made if
measured increases in waler levels are the result of long periods of downtime of the
pumping system(s).
Table 1-Pumping Well Depth Chart
pumped
well
MW-4
MW-26
TW4-19
TW4-20
pre-
pumping
DTW(ft)
61
•50
48
62
average
DTW^
during
pumping
(ft)
75
81
81
82
max
DTW
during
pumping
(ft)
85
IOI
96
99
min
DIW
during
pumping
(ft)
68
74
62
66
pre-
pumping
WL(ft
amsl)
5562
5576
5583
5568
average
WL
during
pumping
(ft amsl)
5547
5544
5551
5547
max WL
during
pumping
(ft amsl)
5554
5551
5569
5564
min WL
during
pumping
(ft amsl)
5537
5524
5535
5530
Page 5
Targets are pioposed lo be adjusted when quarterly monitoring indicates that the average
of the water levels in a group of wells changes by 5 feet or morc relative lo the fourth
quarter. 2008 measurements. The average fourth quarter, 2008 depth to water and
elevation for group i wells was 65 ft and 5557 ft amsl. and for group 2 wells was 59 ft
and 5575 fr amsi. respectively. For example, should the average of the waier levels
measured in the first group of wells increase by belween 5 and 10 feet relative to fourth
quarter. 2008 measurements (from 5557 to 5562 ft amsl). The MW-4 target average depth
to water during pumping would be reduced by 5 feel (from 75 to 70 ft) and the target
water level elevation increased by 5 feel (from 5547 lo 5552 ft amsi). The taiget
maximum and minimum depths to waler during puinping would be adjusted from 85 to
80 ft and 68 to 63 fl. respectively. Subsequent adjustments would be based on additional
increments of 5 feet. For example, if average water levels changed by belween 10 and 15
feet relative to (he fourth quarter. 2008 measuremenls, water level targets would be
adjusted by 10 ft. If deemed necessary based on fuUire waier level monitoring and
capture zone analysis (performed as part of the quarterly moniloring program), additional
adjustments to pumping water level targets may be made to ensure that capture
effectiveness is maintained.
The water levels in pumping wells are monitored on a monthly basis. In addition, the
operating lime, fiow rates and total gallons pumped from each of the pumping wells are
recorded on a monthly basis by the Environmental Heallh and Safety Department.
The Mill shift foreman, or radiation safety department staff, inspects the pumping wells
daily, or more frequently during winter months. The inspection is documenled on the
attached Daily Inspection Repori, a copy of which is maintained in the Mill central fdes."
DRC Response to second bullet in CAL Item 3
The importance and lhe function to the Plan Is lo have procedures and deadlines for the
mechanical operation and maintenance ofthe pumping syslem to assure the puinping system is
operating properly. Details on performance standards for well drawdown or hydraulic capture
should be left to the Correciive Action Plan. Based on this recommendation, the following
parts of rhe Plan need ro be removed;
• The 3^ paragraph in lhe Operaiions section.
• Item 1. "Backgiound", in the Operaiions seclion.
• Item 2. "Quarterly Water Levels", in lhe Operations section.
• Item 3. "Proposed Waler Level Targets" in the Operations seclion.
CAL Item 4
Maintenance Section - Please revise to include:
• PumtyJus system (sysiem) Ihihire(s) - Propose for Executive Secretary approval, the
minimum amount ofday(s) the system will be non-operational due io system
failures before repairs occur and hack in operation. The rationaleand basis for
the proposed minimum day(s) should include hut nol limited lo minimum amount of
time thai ihe syslem can he non-operational before the containment of chlorofonn
plume is lost.
Page 6
• Reporting syslem failure(s) - When a system failure occurs as soon as possible, hul
no latter than 24 hours from lhe lime lhat IUC first becomes aware ofthe
circumstances call the DRC to repori system failure.
A written submission shall also be provided to the Execuiive Secretary within five
days ofthe time lhat IUC becomes aware ofthe system failure. The written
suhmission shall contain:
a) A description ofthe system failure;
h) The period of that the syslem was not in operation:
c) The estimated time lhe sysiem is expected lo continue to he non-
operational:
d) Steps being taken to repair and have syslem operating;
e) Steps Taken or planned to reduce, eliminate, or prevent reoccurrence of
sysiem failure.
System failures during each quarter the will he summarized in the corresp<mding
quauerly gnmndwater monitoring reports.
DUSA Aclions
In the maintenatice section ofthe Plan (page 5) slales:
"All system repairs will be completed within 24 hours of discovery and will be reported lo the
Executive secretary in a written report wilhin 5 days ofthe failure. Each written submission
shall contain xhe following infonnation:
a) A description of the system failures
b) The period of lime that the sysiem was not in operalion
c) The estimated time the system is expected to continue lo be non-operational
d) Steps being laken to repair and have the syslem operational
e) Steps taken or planned to reduce, eliminate, or prevent reoccuiTence of system failure
f) Each system failure will be summarized in the corresponding quarterly groundwaler
monitoring reports'"
In the monitoring and reporting section of the Plan (see page 6) lists items to be reported in the
quarteriy reports. The first item is: "Description ofthe pumping operations including any
operalionai problems encountered during the quarter."
DRC Response
Before CAL item 4 can he satisfied the following modifications are needed to the maintenance
seclion of the Plan (see page 5) [modifications are shown as underlined and deletions are
shown as sirikethrough|:
When a system failure oci^urs and is nol repaired and Fullv mside operational within 24 hours of
discovery DUSA shall call the Executive Secretary to verbally report the svstem failure AW
system repairs will becompleted wiihin 21 hours of naid discovery and will he reported to the
Page 7
Executive Secretary in a written report within 5 days ofthe failure. .Said wTitlen failure report
shall contain the following infoi"mallon:
a) A description of the system failures and their root cause(s)
b) The peiiod of time lhat the syslem was not or will not be in operation
c) The date the system is expected to continue to be non-operational and a deadline by
which the svslem will be repaired and fullv operational
d) Steps being laken lo repair and have the syslem operational
e) Steps taken or planned lo eliminate, and OF prevent reoccuiTence of sysicm failure
f) Each system failure will be summarized in lhe corresponding quarterly groundwater
moniloring reports
In addidon, all system falluie.s will be reported in the following quaiterly chlorofomi
groundw-ater uion'ilonn'j reporr
ADDITIONAL MODIFICATIONS
At the end ofthe Introduction section ofthe Plan the following wording needs to be added:
"This operations and maintenance plan Is required for all pumping wells approved by the
Executive Sectary associated with the chloroform pumping system."
RECOMMENDATIONS
It Is recommended that DRC conditionally approve the Plan so long as the Plan includes the
modifications above.