DSHW-2013-003634 - 0901a06880383da7

May 29, 2013
8200-FY14-24
Division of
and Hazardous Waste
MAY 2 9 2013
ZOXb- 00 3634-Scott T. Anderson, Director
Department of Environmental Quality
Division of Solid and Hazardous Waste
ATTN: Jeff Vandel
P.O. Box 144880
195 North 1950 West
Salt Lake City, Utah 84114-4880
RE: ATK Launch Systems Inc. - Promontory Facility, EPA ID# UTD009081357, Corrosion
Investigation Plan Report for Monitoring Well Screens at ATK Promontory; response to
DSHW2012-009381
Dear Mr. Anderson,
ATK received approval from your office in August 2012 for a plan to investigate the corrosion of
stainless steel well screens in monitoring wells at the Promontory Facility. Attached please find
a report on the result of the investigation.
If you or your staff have questions about the report, or need additional information, please
contact Paul Hancock at [phone].
Sincerely,
Division of
So,ld ™d Hazardous Waste
MAY 2 9 2013
£o\3- 003^,34.
Corrosion Investigation Report for
Monitoring Well Screens at ATK
Promontory
May 2013
Division of
Solid and Hazardous Waste
MAY 2 9 2013
ATK
Corrosion Investigation Report for
Monitoring Well Screens at ATK
Promontory
May 2013
Corrosion Investigation Report
for Monitoring Well Screens at
ATK Promontory
May 2013
Corrosion Investigation Report for Monitoring Well Screens at ATK
Promontory
Purpose
Corrosion of stainless steel well screens in ATK Promontory groundwater monitoring
wells has been established through visual and analytical data. An ongoing concern with
the stainless steel well screens is that severe corrosion could potentially limit water flow
through the well. In April 2012 a plan for evaluating those well screens was developed
and approved in August 2012 by the Utah Division of Solid and Hazardous Waste. This
report discusses the implementation of the plan and the results of the evaluation.
Background
Monitoring well construction at Promontory started in 1985. Around that time, the EPA
recommended the use of stainless steel for monitor well screens and pumps as it was
believed to be inert to solvents or other contamination that may in the groundwater. As a
consequence, a large number of wells at Promontory were constructed with 316 stainless
steel screens and dedicated pumps in these early years. This changed in later years to
PVC screens. However, even these PVC wells were constructed using 316 stainless steel
screen centralizers and connectors. One of the primary ingredients in 316 stainless is
chromium at 16 to 18 percent. Molybdenum is also used at 2 to 3 percent. ATK has
found that corrosion of the stainless steel results in high levels of chromium and
molybdenum in unfiltered groundwater samples.
Investigation
In November 2013, a down-hole camera was used to view and record the condition of the
well identified in the Investigation Plan. A copy of the video recordings from each of the
wells is found in a DVD provided with this report. To view the individual well videos on
the DVD, click on the skip " > |" control on the screen to advance to the next well. The
well identification is in the upper left hand corner of the display. Please note, in order to
save viewing time, the travel of the camera through the upper portion of the well has been
accelerated until the camera enters the water and the well screen.
Evaluation of the Well Screen Corrosion
The wells evaluated are listed in Table 1 along with an evaluation of the screen corrosion
level. The evaluation of the degree of corrosion in the well screens is subjective.
However, it is assumed that if the horizontal slots in the screen are still visible and absent
of a severe, heavy corrosion layer that the well is still functional. The camera faces
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Corrosion Investigation Report
for Monitoring Well Screens at
ATK Promontory
May 2013
downward so a direct horizontal view was not possible, however, the horizontal slots and
overall corrosion amount of the screens was evident.
Table 1
Wells Inspected Using Down-hole Camera
Well Basis for Inspection Evaluation
D-6 Cleaned in 2007, determine
how quickly corrosion
returns and condition of
oldest wells.
Well screen determined to
be PVC, no corrosion.
A-10 Next oldest well series; in
area of relatively low TDS
Well screen corrosion was
very light, horizontal slots
were evident. Upper
connection to the screen
shows heavy corrosion
B-4 Older well in area with
increasing TDS
Well Screen corrosion
overall was light, horizontal
slots are evident. A few
corrosion nodules at screen
connection.
E-6 Moderate aged well, in area
with increasing TDS
Showed some well screen
corrosion, horizontal slots
evident
F-3 Relatively new well in area
with higher TDS
A heavier layer of corrosion
in well screens, horizontal
slots somewhat less visible
but still evident, some
pockets of severe corrosion
LF-2 Newest Stainless Steel
Well Series
Minimal light corrosion,
screen slots are evident.
Conclusions
The corrosion of the well screens overall was not severe and did not appear to block the
horizontal well screen slots. Taking into account the fine grained formations and lower
conductivities at the location of many of the wells; it could be assumed that the
permeability of the well screens is higher than the surrounding soil. The high or severe
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Corrosion Investigation Report
for Monitoring Well Screens at
ATK Promontory
May 2013
corrosion appeared to be typically at the connection between the screen and the upper
portions of the well. The cauliflower like growth, indicative of severe corrosion, seemed
to be soft and easily dislodged and tended to be in discrete locations. This is believed to
be a bacterial growth caused by iron bacteria which tends to grow best at the transition
zone between more aerobic and anaerobic conditions closer to the water surface of a well.
Another theory for the high corrosion observed at the joint between the screen and the
PVC pipe is that the 4.5 inch to 4 inch reducer used for the connection may result in
galvanic action caused by two dissimilar metals. The wells in higher TDS locations
appear to be more subject to corrosion of the stainless steel screens. This indicates that
groundwater TDS rather than the age of the wells is a greater indicator of corrosion. It
was unexpected to find that the oldest well in the study, D-6, was constructed with a PVC
screen. The D well series were the first to be drilled in 1985. This was prior to the first
EPA Groundwater TEGD published in September 1986 which recommended stainless
steel well screens in areas with potential VOC contamination. The D wells could
therefore have a longer usage life.
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