Cornhusker Army Ammunition Plant_Fillable_v5
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Iowa Western Community College *
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Course
103
Subject
Geography
Date
Dec 6, 2023
Type
Pages
13
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Cornhusker Army Ammunition Plant
Overview
In 1942 the Cornhusker Army Ammunition Plant (CHAAP) was
built a few miles west of Grand Island, NE to produce
munitions to support the efforts of WWII.
It was established as
a government owned/contractor operated (GOCO) facility with
the Quaker Oats Company as the first contractor to operate
the plant.
During the peak of WWII, they employed 4,229
workers to aid in the loading of 90 and 260-pound
fragmentation bombs, 1,000 and 2,000-pound general
demolition bombs, and 105 mm high explosive artillery shells
for the Howitzer.
Over the course of WWII, it is estimated that
more than 10 million bombs and shells were assembled there.
To learn more about the history of the plant, watch the
following short video:
http://www.nebraskastudies.org/1925-
1949/the-war-nebraska-stories/nebraskans-pitch-in/
CHAAP was again active during the Korean War and Vietnam
until it was shut down in 1973.
The plant has been on standby
status since then and the land was leased for agriculture,
grazing and wildlife management.
In the 1980’s, it was
discovered that the groundwater was contaminated with the
explosives TNT (2,4,5-trinitrotoluene) and RDX (Cyclonite) in addition to smaller amounts of RDX and
other chemicals.
In 1987, CHAAP was declared a Superfund site and added to the National Priorities List
which is overseen by the Environmental Protection Agency (EPA).
Superfund sites are polluted locations
in the United States requiring a long-term response to clean up hazardous material contaminations.
The
U.S. Army Corps of Engineers was tasked with overseeing the clean-up and reporting to the EPA.
You have been hired by the Corps of Engineers to complete a site assessment and aid in developing a
remediation plan.
The first step in this process is to do a preliminary site analysis using existing data.
You will then have the opportunity to gather additional data to determine the extent and the source of
the contamination.
Finally, you will give recommendations towards a remediation plan to clean up the
contamination.
Stage 1: Preliminary Analysis
You have just started the task of completing a preliminary site analysis of the plant and the surrounding
regions.
The goal of Stage 1 is to gain a good understanding of the situation in order to determine what
additional data you need to collect (Stage 2) in order to create a remediation or clean-up plan (Stage 3).
During Stage 2 you will be able to drill wells and test for contaminants; however, you don’t have
unlimited funds so you will need to make informed decisions on where these wells will be drilled.
To aid
in this process you will want to compile information on both plant operations and the geology of the
region.
For some background information on groundwater and how groundwater moves,
read through
pages 130-133 in your lab manual.
Figure 1
. During WWII, many rural
women went to work in military
plants like the CHAAP. Source NARA
Take a few minutes to brainstorm about the types of information you would want to collect for a
preliminary analysis.
What questions would you ask about CHAAP and the geology?
What data sets
would you want to look at?
What preliminary analysis could you complete using these data sets?
1.
In the space provided, write a short paragraph to outline your approach to completing the
preliminary analysis.
Be sure to include at least three questions you would need to answer as
well as address the information and data sets that you will need to collect and analyze in this
process.
Layout & Operations of CHAAP
The Cornhusker Army Ammunition Plant is divided into different regions as can be seen on Figure 2
below.
The load, assembly and packing of the ammunition took place in the load lines, which were a
collection of large buildings interconnected with a series of covered walkways that housed conveying
systems.
Empty shells came in the South end of the 4 main load lines and worked their way up the line
until the finished product emerged from the North end.
The bombs were then transported to one of the
219 storage bunkers called igloos before they were shipped out via rail lines that ran between the load
lines and magazine areas. These storage bunkers can be seen in the aerial photo shown in Figure 2
(North & South Magazine Areas).
A smaller 5
th
load line was built for the production of fuses and
boosters during the Korean War and the manufacturing of micro gravel mines during Vietnam.
The explosives were received in flake form and then screened and sifted for use in the ammunitions. The
dust created from this process was sucked into the ventilation and washed from the air with Schneible
units (wet scrubbers).
Wastewater was generated from the Schneible units as well as from cleaning of
machinery and other surfaces. Some of this wastewater ran via interior building drains into a concrete
pit where a filter bag (made of canvas-like material) was placed to collect the solid explosive particles.
The wastewater was then transferred via concrete channels into 56 earthen surface impoundments,
which were located near the five production areas.
Dried solids from the bottom of the pits were
periodically scraped and ignited, along with other contaminated materials, at the burning grounds in the
northwest corner of CHAAP.
The northwest corner of the grounds also contained a sanitary landfill and
a pistol range.
The main administration building was located in the southeast section of the grounds
along with base housing.
To the north of the housing was a fertilizer manufacturer (marked as nitrate
on Fig. 2) as well as a shop area with maintenance buildings and a storage area.
2.
From this description,
where
would you expect
to see the most contamination and what would be
the source of this contamination?
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Figure 2
. Aerial view (right) of the CHAAP with an illustrated map (left) showing the locations of interest.
Stratigraphy & Permeability
Topsoil
Soils at CHAAP are predominantly windblown silts.
On-site,
topsoil depths range from 1-2’; however the thickness varies in
surrounding area and can reach up to 20’. The soils are
generally described as dark brown to black, organic silty clay.
Grand Island Formation
This is underlain by the Grand Island Formation (see Figure 3),
which is predominantly Quaternary age fluvial sands and
gravels deposited during the Kansan stage of glaciation.
This
formation averages 40 to 60 feet in thickness in the study area.
Since we are concerned with groundwater contamination, it is
important to know about the
hydraulic conductivity
of the
rocks or sediment.
Similar to permeability, the hydraulic
conductivity is a measure of how fast (in centimeters per
second) water flows through the rocks.
To gain a better sense
of what hydraulic conductivity is and how it is measured, you
are going to use a simple falling head permeameter to measure the hydraulic conductivity of two
samples.
The first sample is a fine sand and the second sample is a coarse sand similar to what you
would find in the Grand Island Formation. The procedure to calculate the hydraulic conductivity is
outlined in Exercise 2 in your lab manual (page 135).
Since you do not have access to the materials or
samples, some of the steps have been completed for you and recorded.
The video for Sample 1: Fine
Sand can be found at:
https://use.vg/96OO0i
and the video for Sample 2: Coarse Sand can be accessed
here:
https://use.vg/zN5LpQ
.
Step 1 has been completed as you can see on the videos, and the height,
L, of the samples has been set to 10 cm (Step 2).
Using the videos, follow along with the remaining steps
to calculate the hydraulic conductivity of both samples.
In Step 7, you will need to calculate a natural
log (ln).
If you do not have access to a scientific calculator you can type ‘scientific calculator’ into a
google search and one will be provided for you. As you work through the process complete the table
below.
3.
Hydraulic Conductivity Experiment
Sample 1:
Fine Sand
Sample 2:
Coarse Sand
Height from bottom of permeameter to the top of
the sample (in cm)
L =
10 cm
10 cm
Initial height of the water as measured from the
bottom of the tube (in cm)
h
1
=
Water height when you stopped timing (in cm)
h
2
=
Time (in seconds)
t =
Hydraulic Conductivity (in cm/s)
K =
Figure 3
(left). Stratigraphy of the
subsurface layers at CHAAP
4.
How do your hydraulic conductivity results compare with typical values for your material type?
(See Table 6-2 in your lab manual)
5.
Based on your hydraulic conductivity measurements, which material (sample 1 or sample 2)
would make
the best
aquifer and why?
Using the same procedure outlined in the video, but using
better and very well calibrated equipment, Scientists from
Oregon Health and Science University calculated the
hydraulic conductivity at various depths from two cores
drilled through the Grand Island Formation.
One-foot
sections of the core were sampled, dried, mixed and packed
into a falling-head permeameter. They found that the
hydraulic conductivity varies slightly between different
layers of sediment, but ranges from 10
-1
to 10
-4
cm/s (see
Figure 4).
6.
Based on the hydraulic conductivity
measurements, would this unit make a good
aquifer or would it be a good aquitard? Explain your
answer.
Fullerton Formation
The Fullerton Formation, also known as the Blue Clay unit, is a widespread and more or less continuous
deposit of silt and clay thought to have been deposited during the Aftonian interglacial stage.
It ranges
in thickness from 5-15 feet and can be found throughout the study area at depths ranging from 45 to 70
feet below ground surface.
Figure 4
. Measured hydraulic conductivity
profiles through the Grand Island Formation
from test holes located near load line 2.
Measured by laboratory permeameter.
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7.
Based on the description of the Fullerton Formation, what values of hydraulic conductivity
would you expect to see?
8.
Would the Fullerton Formation make a good aquifer or would it be a good aquitard? Explain
your answer.
Holdrege Formation
The Holdrege Formation consists primarily of fluvial sands and gravels deposited during the Nebraskan
glacial period.
This is a paleovalley fill unit that formed when erosional valleys cut into the underlying
Ogallala Formation and then became infilled with river sands and gravels.
This unit is 30’ thick under
CHAAP and increases to more than 220’ to the north as you reach the center of the paleovalley.
The
sediments also vary along the paleovalley axis with more silt and clay near the margins of the valley that
grade into sand and gravel near the center of the infilled valley. Under CHAAP the sediments are
relatively finer grained with coarser materials to the north.
9.
Would the Holdrege Formation make a good aquifer or would it be a good aquitard? Explain
your answer.
10.
Are there any confined aquifers in this region?
Explain your answer.
11.
Which layers/formations would likely be contaminated? Explain your answer.
Water Table
Since we are working with groundwater contamination, it is important to determine the direction of
groundwater flow. The elevation of the water table can provide insight into this. Revisit pages 130-133
in the lab manual to learn more about the water table, then read through the introduction to Section IV.
Learning Groundwater Flow from Maps in your lab manual (page 137). Work through Exercise 4 in your
lab manual and then compare your answers to the Exercise 4 answer key that can be found on Canvas
(you will not turn this in)
.
Now that you have an idea of how to determine groundwater flow, you are
going to follow a similar process in the study area.
While seasonal fluctuations of the water table occur over time, comparison of water-level data near
CHAAP indicate the configuration of the water table has remained fairly constant over time. The depth
to the water table varies from 10-30 feet below the surface.
Figure 5 shows the elevations of the water
table above sea level.
12.
Contour the top of the water table using 10’ contour intervals on Figure 5.
Draw arrows on the
diagram to indicate the direction of ground water flow.
Please note that the figure provides
water table
elevations above sea level
and not depths to the water table (as you saw in exercise
4 in your lab book) so think carefully when drawing your arrows.
If you need help with how to
add contour lines to the map using Adobe Acrobat Pro you can view this tutorial:
https://use.vg/2YqSKx
.
Be sure to label your contour lines.
13.
On Figure 5, outline the most likely location of the contaminate plume based on all of the
information you gathered so far.
14.
The city of Grand Island’s municipal water supply is through a well field located southeast of
Grand Island near the Platte River (~10 miles SE of CHAAP).
What is the likelyhood that the
city’s water supply will be impacted by the contamination?
Explain your answer.
Figure 5
. Elevation of the water table as determined through well data from April 2013 and estimated
values (data source:
https://maps.waterdata.usgs.gov/mapper/index.html
) .
On this map you will be
asked to contour the top of the water table, draw arrows indicating the direction of groundwater flow
and predict the location of the contaminant plume (Questions 12 & 13)
Grand
Island
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Stage 2: Gathering additional data
Now that you have completed the preliminary analysis of the Cornhusker Army Ammunition Plant you
have the opportunity to drill wells to test and monitor the contamination levels of TNT and RDX. The
goal is to narrow down the source of the contamination and oultine the contaminant plume. This
information is needed to create a remediation plan (Stage 3).
You will have two opportunities to request data. For the first round, you will be allowed to drill
monitoring wells at 1
5
locations within the study area. After receiving well data for those locations, you
will be allowed to request information for
10
additional monitoring wells in a 2
nd
round of data
acquisition.
In selecting your well locations, it is useful to understand more about how different compounds behave.
TNT has a tendency to be sorbed onto soils and does not migrate as far as RDX which moves more
readily with the flow of groundwater.
Round 1 of data collection
In canvas there is an assignment called Week2: Groundwater Data Request 1.
In that assignment you
will find a data request form that must be filled out and submitted to your instructor. On the data
request form, you will need to indicate your well locations on a map and provide PLSS coordinates for
each monitoring well you plan to install. After the deadline, your instructor will return the Data
Request Form with the TNT and RDX concentrations (in micrograms per liter) for each well location.
15.
Outline your strategy for selecting the initial 1
5
monitoring well locations. What information
from stage 1 did you use in making your selections?
Round 2 of data collection
Now that you have had a chance to analyze the data from Round 1, you may request an additional
10
wells through the assignment Week 2: Groundwater Data Request 2.
Using the same form from Round
1, mark the new well locations on the map using Red Circles and provide the corresponding PLSS
coordinates on the Round 2 table.
16.
Outline the strategy that you used for selecting the
10
wells in round 2 of data collection.
Data analysis
17.
Use the information that you have collected in Stage 1 and 2 to outline the plume of
contamination on the map below.
18.
What is the primary source of contamination?
Figure 6.
Map of the Cornhusker Army Ammunition Plant (blue outlines) showing PLSS coordinates. LL =
load lines. On this map you will be asked to outline the primary contamination plume (Question 16) as
well as the location of a pumping well (red dot) and a permeable reactive barrier (red line) (Question 19
& 20)
STAGE 3: Remediation
The remediation of the contamination at Cornhusker Army Ammunition Plant started in 1997 and is still
ongoing today.
There were many components to clean-up.
The first priority was to provide bottled
water to ~400 homes until permanent access to clean water could be obtained.
In addition to contamination of the groundwater, there were many places across the plant where the
contaminated soil had to be dealt with.
An incineration program was put into place to remove and burn
the contaminated soil. In total, it is estimated that 40,000 tons of soil was burned.
The excavated pits
were backfilled with off-site sand and gravel.
To treat the contamination of the groundwater a treatment plant was constructed in 1997.
Contaminated groundwater is extracted at 7 onsite wells.
After passing through a carbon filtration
system the drinking water quality groundwater discharges to drainage ditches on the site.
The wells
were places in the region of highest contamination.
The offsite contamination plume treatment is
through monitored natural attenuation and long term monitoring.
19.
On Figure 6 place a red dot in the location where you would place an extraction well to pump
out the contaminated water for treatment.
Prior to the early 2000’s the main remediation technique to deal with contaminated groundwater was
to pump and treat as was done at CHAAP.
In the last 20 years, new remediation techniques have risen
to the forefront.
One technique that shows promise is the use of Permeable Reactive Barriers or PRBs
(see Figure 7).
The main concept is that you dig a trench perpendicular to the direction of groundwater
flow and install a wall of a mixture of iron filings and sand (PRB).
The contaminated water flows through
this wall and the iron reacts with the contaminats to produce new compounds which precipitate out of
the groundwater resulting in clean water downflow.
This
technique has a couple of advantages over pump and
treat.
As TNT tends to sorb onto soil, pump and treat
techniques are not as effective as you must pump for long
periods of time to remove the TNT.
It is also less
expensive to insert a PRB compared to a treatment plant.
One downside is that not much research has been done on
the effectiveness of PRBs at removing TNT and RDX.
A
small PRB was installed at CHAAP as a test case for this
technique.
20.
If you were going to install a Permeable Reactive Barrier at CHAAP to treat the main
contaminant plume where would you place it?
On Figure 6, place a red line to indicate the
location of the PRB that you would install.
Figure 7.
Permeable Reactive Barrier
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References
To learn more about the history of the plant visit the following sites:
•
http://www.nebraskastudies.org/1925-1949/the-war-nebraska-stories/nebraskans-pitch-in/
(NET Video)
•
http://uxoinfo.com/blogcfc/client/includes/uxopages/sitedata1.cfm?uxoinfo_id=01NE0001
•
https://livinghistoryfarm.org/farminginthe40s/life_10.html
•
https://history.nebraska.gov/blog/bombs-away
•
http://www.nebraskastudies.org/1925-1949/arsenal-for-democracy/the-martin-plant-and-
women/
(photos on left side)