United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
. EPA/ROD/R07-89/029
September 1989
Superfund
Record of Decision
Hastings Groundwater, NE
-------
50272-101
REPORT DOCUMENTATION
PAGE
1. REPORT NO.
EPA/ROD/R07-89/029
3. Recipient's AcceMlon No.
4 Title and Subtitle
SUPERFUND RECORD OF DECISION
Hastings Ground Water Contamination, NE
First Remedial Action
5. Report Dale
09/26/89
7. Authors)
8. Performing Organization Rept No.
9 Performing Organization Name and Addresa
10. ProjecVrask/WorkUnitNo.
11. Contract(C) or Grant(G) No
(C)
(G)
12. Sponsoring Organization Name and Addreu
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
13. Type of Report & Period Covered
800/000
15. Supplementary Notes
16. Abstract (Limit. 200 words)
The Hastings Ground Water Contamination site is a contaminated aquifer in the vicinity
of the city of Hastings, Adams County, Nebraska. The site consists of several source
areas, referred to as subsites, contaminated with various chlorinated volatile
industrial chemicals. This Record of Decision addresses the Well Number 3 subsite which
consists of a ground water plume contaminated with carbon tetrachloride emanating from a
former grain storage facility. The State first identified volatile organic contaminatio"-
in Well Number 3 in 1983. Between 1986 to 1989 EPA conducted a field investigation whid
identified the grain storage area as the source of ground water contamination probably
resulting from accidental spills of liquid fumigants used during grain storage. This
interim source control operable unit was developed to reduce the migration and volume of
volatile contaminants present in the soil. The primary contaminants of concern in the
soil which impact the ground water are VOCs including carbon tetrachloride and
chloroform.
The selected remedial action for this site includes utilization of in-situ soil vapor
extraction to remove approximately 400 pounds of VOCs from the soil; treatment of vapor
emissions by a vapor phase granular activated carbon system; and replacement of spent
(See Attached Sheet)
17. Document Analysis a. Descriptors
Record of Decision - Hastings Ground Water Contamination, NE
First Remedial Action
Contaminated Media: soil
Key Contaminants: VOCs (carbon tetrachloride)
b. Identifiers/Open-Ended Terms
c. COSATI Field/Group
18 Availability Statement
19. Security Clasa (This Report)
None
20. Security Class (This Page)
None
21. No. of Pages
31
22. Price
(See ANSI-Z39 18)
See Instruction* on Reverse
OPTIONAL FORM 272 (4-77)
(Formerly NTIS-3S)
Department of Commerce
-------
EPA/ROD/R07-89/029
Hastings Ground Water Contamination, NE
First Remedial Action
m>. Abstract (Continued)
granulated activated carbon filters followed by offsite disposal at an approved treatment
facility for regeneration or incineration. The estimated capital cost for this remedial
action is $874,000 with an annual O&M of $154,000.
-------
RECORD OF DECISION DECLARATION
INTERIM SOURCE CONTROL OPERABLE UNIT
SITE NAME AND LOCATION
Well Number 3
Hastings Ground Water Contamination
Hastings, Nebraska
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected response action
for the Well Number 3 subsite developed in accordance with the
Comprehensive Environmental Response, Compensation and Liability
Act of 1980 (CERCLA), as amended by the Superfund Amendments and
Reauthorization Act of 1986 (SARA), 42 USC §9601 et. seq. and
consistent with the National Oil and Hazardous Substances
Pollution Contingency Plan (NCP) to the extent practicable.
This decision is based upon the contents of the
administrative record for the Well Number 3 subsite.
In accordance with CERCLA Section 121(f)(l)(E) and (G) , the
state of Nebraska reviewed and commented on the Engineering
Evaluation and Cost Analysis for an Expedited Response Action for
Soil and Soil Gas (EE/CA) Well Number 3 Subsite. The state
concurs in the selected action for this operable unit and
has determined, through a detailed evaluation, that the selected
action is consistent with its laws and regulations.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from
this site, if not addressed by implementing the response action
selected in this ROD, may present an imminent and substantial
endangerment to public health, welfare or the environment.
DESCRIPTION OF THE ACTION
This interim source control operable unit was developed to
protect public health and the environment by controlling and
reducing the migration and volume of contaminants present in the
soil-gas which overlies the aquifer. The operable unit is fully
consistent with all planned future activities. Future activities
will be addressed in subsequent Records of Decision and will
include a decision on possible remediation of contaminated ground
water.
-------
The major components of the selected action are as follows:
- Soil vapor extraction (SVE) and treatment of air
emissions by granular activated carbon (GAC)
- GAC will be transported off-site to an approved
treatment facility for regeneration or incineration
- Monitoring contaminants in the soils above the aquifer;
Monitoring ground water contamination at the site;
and
- Monitoring of the air system emissions.
DECLARATION
This interim action is protective of human health and the
environment, attains federal and state requirements that are
applicable or relevant and appropriate to this action and is
cost-effective. This action satisfies the statutory preference
for actions that employ treatment that reduces toxicity, mobility
or volume as a principal element and utilizes permanent solutions
and alternative treatment technologies to the maximum extent
practicable. This action will mitigate future releases to the
ground water; however, this action will not address other
contaminant source areas. Due to its limited scope of migration
control, this action does not address remediation of the ground
water. Subsequent remediations are planned for the site that
will address all remaining concerns.
Date /^orris/Kay
Regional Administrator
Attachments: Index to Administrative Record
Decision Summary
Responsiveness Summary
-------
RECORD OF DECISION
DECISION SUMMARY
HASTINGS GROUND WATER CONTAMINATION
WELL NUMBER 3
HASTINGS, NEBRASKA
Prepared By:
U.S. Environmental Protection Agency
Region VII
Kansas City, Kansas
September, 1989
-------
Record of Decision
Decision Summary
Contents
Section Page
I. Site Description 3
II. Site History 4
III. Enforcement History 10
IV. Community Relations 10
V. Site Characteristics 11
VI. Risk Assessment 17
VII. Scope of Operable Unit 20
IX. Summary of Alternatives 20
X. Evaluation of Alternatives 21
XI. Comparison of Alternatives 25
XII. Selected Alternative 28
XIII. Cleanup Levels 28
XIV. Operation and Maintenance 28
XV. Future Action 28
XVI. State Role. 29
-------
DECISION SUMMARY
WELL NUMBER 3 SUBSITE
HASTINGS GROUND WATER CONTAMINATION
SITE DESCRIPTION
The Hastings Ground Water Contamination site is located in
south central (Adams County) Nebraska. The location of, Adams
County and Hastings is shown by Figure 1. Hastings has an
estimated population of 23,000. This site consists of several
source areas which are referred to as "subsites." These subsites
are identified with various volatile industrial chemicals. The
Well Number 3 subsite consists of a carbon tetrachloride ground
water plume which extends eastward from a former grain storage
facility. This subsite is located in the west central part of
Hastings. The affected area lies between B Street and Second
Street in the north-south direction, and between Maple Avenue
and Kansas Avenue in the east-west direction (see Figure 2).
The Well Number 3 Subsite is located in the Central
Industrial Area of the city which contains commercial and
industrial properties situated along the Burlington-Northern
Railroad right-of-way. Well Number 3 source area is located on
property that was formerly used as a grain storage facility.
Records indicate that the property was previously owned by the
Burlington Northern Railroad. In 1959, the property was leased
by the railroad to Farmers Grain Storage, Inc., and later, in
1972, purchased by Farmers Grain Storage, Inc. The current
owner, W.G. Pauley Lumber Co., purchased the property in 1975.
Hastings Public Water Supply Well Number 6 is located four
blocks west of the source area. Well Number 11 is located four
blocks north-east of the source area. Wells Number 9, 10 and 20
are all downgradient of this site. Well Number 3 is one mile
downgradient from the identified source area. This well was
taken out of service in 1985. The municipal wells, shown on
Figure 2, were sampled by the state of Nebraska; the data are
presented in Table i:
SITE HISTORY
The Hastings Groundwater Contamination site consists of
an aquifer contaminated with industrial chemicals, primarily
chlorinated volatile organics. Due to this contamination, the
City of Hastings decommissioned several of its wells and the CMS
public supply system operating east of Hastings decommissioned
one well.
-------
Ğ > <*t >t#^ i i i A y
u./'_>:irLj- Ui^/
P^TJTT^
Ji&r
v*.J ft -J--J
:-1 -1 -> *
HI ,MğU'COUNIV
.5rn i,,"i ; ,
Site Location Map
HASTINGS, NEBRASKA
Hastings
Figure 1
-------
WELL LOCATIONS WELL Ğ3 AREA
M-6
500 FEET
JL.LY 1989
CW-1, MW-W, SHALLOW
MONITORING WELLS
-§- MW-23. MONITORING
WELL SCREENED
FULL DEPTH
M-10, CITY WELL
M-3 DECOMI8SIONED
-------
TABLE 1
Range of Concentrations of Volatile Organic Compounds
City of Hastings, Nebraska.
1983 - 1984
Municipal Wells
Concentrations in micrograms per liter (ug/1).
PARAMETER
M-3
M-6
M-9
M-10
M-ll
Carbon
Tetrachloride
(CC14)
Chloroform
27.1 -
46.4
ND
NA
ND
ND
ND
ND
ND
NA
0.15
1,1-Dichloroethene ND NA ND ND NA
(DCE)
Trans-1,2- ND NA ND ND NA
Dichloroethene
Tetrachloroethene ND NA ND ND NA
(PCE)
Trichloroethylene ND ND ND 19.6 - 0.42
(TCE) 46.5
1,1,1- ND NA ND ND NA
Trichloroethane
(TCA)
Ethylene Dibromide ND NA NA ND NA
(EDB)
Notes
Ground water data (1983-1984) presented here reflect data
from two wells (M-3 and M-10) which have since been taken
out of regular service and/or disconnected from the
distribution system. The highest contaminant
concentrations were found in 1983 when the wells were in
use.
Data was obtained from state of Nebraska data reports and
the REM II - Ground Water Evaluation, Hastings Groundwater
contamination Site, Hastings, Nebraska, May 7, 1987.
Samples analyzed by EPA's Lab in September, 1984 were
consistent with the above data.
NA - parameter not analyzed.
ND - compound not detected.
1983 and 1984 analyses were reported by the state of
Nebraska.
-------
In 1983, the Nebraska Department of Health (NDOH) sampled
the public water supply system of Hastings in response to citizen
complaints of taste and color in the drinking water. That same
year, NDOH and the Nebraska Department of Environmental Control
(NDEC) began investigating wide-spread ground water contamination
in the Hastings area. During this investigation, samples
collected from Well Number 3 indicated that the well was
contaminated with carbon tetrachloride (CC14).
In 1984, the state of Nebraska installed five pairs of
monitoring wells in the City of Hastings to define the extent of
the contamination. The Environmental Protection Agency (EPA)
began to sample wells on a quarterly basis in 1985. Results of
the production wells are given in Table 2.
Several locations on the west side of Hastings upgradient
of City Well 3 were suspected as source areas for the CC14
contamination. Between 1986 and 1989 EPA performed a field
investigation to identify and characterize these suspected source
areas. Analyses of soil gas samples were used to identify and
define the source areas. The results of the data, which are
presented in the EE/CA, indicated that the former grain storage
facility was the area from which the CC14 found in Well Number 3
emanated. No other sources of contamination were indicated by
the data. Results of the soil-gas sampling taken from depths of
20 to 22 feet at the Well Number 3 subsite are shown in Figure 3.
These results indicate the CC14 source is located in an area at
the east corner of the old grain storage building.
The contamination found in the water at the Well Number 3
subsite is believed to be a result of accidental spills of grain
fumigants that occurred at the former grain storage facility
prior to purchase by the current owner. During the 1960's when
there were large grain crop surpluses, extensive amounts of grain
were stored for long periods of time while waiting for market.
Fumigants were used on the grain in an effort to keep the grain
in good condition. A primary ingredient of the liquid grain
fumigants that were used in the 1960's and 1970's was CC14. The
presence of volatile organic compounds in the ground water
downgradient from the former grain storage facility is consistent
with liquid fumigants, having been released into the soil at the
former grain storage facility, migrating downward and entering
the ground water.
-------
TABLE 2
Range of Concentrations of Volatile Organic Compounds
City of Hastings, Nebraska
1985-1989
Municipal Wells
Concentration in micrograms per liter (ug/1).
PARAMETER
Carbon
Tetrachloride
(CC14)
Chloroform
1, 1-Dichloroethene
(DCE)
Trans-l, 2-
Dichloroethene
1 , 2-Dichloroethene
(Total)
Tetrachloroethene
(PCE)
Trichloroethylene
(TCE)
1,1,1-
Trichloroethane
(TCA)
Ethylene Dibromide
(EDB)
M-3
22.0 -
32.0
ND
ND
ND
ND
ND
ND
ND
NA
M-6
ND
ND
ND
ND
ND
ND
ND
ND
ND
M-9
ND
ND
ND
ND
ND
ND
ND
ND
ND
M-10
ND
ND
ND
ND
ND
ND
ND -
21.0
ND -
0.3
NA
M-ll
ND
ND
ND
ND
ND
ND
ND -
2.0
ND
ND
M-20
ND
ND
ND
ND
ND
ND
ND -
5.0
ND
ND
*M-20 is a new well constructed in 1987 and initially sampled by
the EPA in May, 1988.
NOTES:
Ground water data presented here reflects data found in M-3
and M-lO which have since been taken out of regular service
and/or decommissioned. CC14 concentrations were higher when
these wells were in service.
-NA - parameter not analyzed.
ND - compound not detected.
- Data were obtained from the REM II - Ground Water Evaluation,
Hastings Groundwater Contamination Site, Hastings, Nebraska,
May 7, 1987; and from EPA laboratory reports.
- The above analyses were reported by EPA Labs and EPA
Contract Labs.
-------
Second St.
-------
An Engineering Evaluations and Cost Analysis for an
Expedited Response Action for Soil and Soil Gas Well Number 3.
Subsite (EE/CA) dated July 24, 1989 was released by EPA for
public comment on July 31, 1989. The public comment period for
this subsite was closed on August 28, 1989. The EPA has prepared
a responsiveness summary which addresses the comments received
(Attachment A).
The EPA has no information indicating that hazardous
substances were ever generated at the site. Therefore, no onsite
burial of wastes is suspected.
Public access to the subsite is not restricted at this
time; however, the owner of the subsite has been advised by EPA
that precautions should be taken when response activities are
underway so that soils that might be contaminated are ,not
disturbed.
ENFORCEMENT HISTORY
History of this site indicates that this property was leased
to the Farmers Grain Storage, Inc. in the 1960's and later sold
to its current owner, W.G. Pauley Lumber Co. in 1975.
Information request letters were sent to W.G. Pauley Lumber Co.
and one of the past owners to determine use of grain fumigants at
the site. The current owner uses the former grain storage
buildings as warehouses for lumber. It has been determined,
through EPA's investigation, that CC14 was used by Farmers Grain
Storage, Inc. Additional information requests are being prepared
for former shareholders of Farmers Grain Storage, Inc. to further
determine, among other things, the past use of CC14 and
chloroform at this site. Farmers Grain Storage, Inc., was
dissolved in 1978 and no successor corporations are known to
exist. The investigation of potentially responsible parties
(PRPs) is ongoing; EPA has not yet notified anyone of their PRP
status at this subsite.
COMMUNITY RELATIONS
Community relations activities for the Hastings Ground Water
Contamination site were initiated by the EPA in 1984 with the
development of a Community Relations Plan. Since December 1984,
EPA has conducted meetings periodically with Hastings city
officials to update them regarding site work and findings.
The EPA Region VII Public Affairs Office has written several
Fact Sheets and provided them to parties who have expressed an
interest in the Hastings Ground Water Contamination Site. The
public affairs office also responds to inquiries from news media
and members of the public regarding this site. The most recent
Fact Sheet was prepared in July, 1989.
10
-------
A public meeting was held on August 10, 1989 to provide the
public an opportunity to comment on the EE/CA. Concerns
regarding the environmental impacts of contamination and the
relative merits of alternative response actions were voiced. A
responsiveness summary, which addresses the comments and
questions raised, is attached to this ROD as Attachment A. This
summary also addresses comments made during the course of the
remedial investigation.
SITE CHARACTERISTICS
Investigations conducted by EPA during 1987-1989 show that
the highest levels of CCl* contamination in the soils and soil-
gas occur in the area defined by the soil-gas contours
illustrated in Figure 3, which depicts the levels of CC14
contamination in shallow borings at depths of 20-22 feet. Figure
3 also indicates that the CC14 contamination is concentrated
within a small area near the outside wall of the eastern
warehouse at the subsite. The highest CC14 concentration in deep
borings, as indicated by Figure 5, is 1200 parts per million by
volume (ppmv), found at a depth of 110 feet.
Data presented in the EE/CA also show high levels of CC14
and chloroform in the ground water at the subsite. As indicated
in Table 4, analyses of samples taken from CW-1, the monitoring
well installed at the subsite, revealed the presence of CC14 at
levels ranging from 110 parts per billion (ppb) to 270 ppb and
chloroform ranging from non-detect to 68 ppb. These samples
confirmed the results from borehole water samples taken during
the remedial investigation which indicated the presence of CC14
and chloroform.
Pursuant to the authority of the Safe Drinking Water Act
(SDWA), 42 USC §300(g), EPA has established a Maximum Contaminant
Level (MCL) for CC14. MCL refers to the maximum permissible
level of a contaminant in water which is delivered to any user of
a public water system. The MCL of 5 ppb has been established for
CC14. As indicated in this document, the MCL for CC14 has been
exceeded. The MCL for chloroform is 100 ppb; analyses of samples
collected indicate this MCL has not been exceeded.
CC14 and chloroform, as members of the volatile organic
compounds (VOC) family, readily form vapors because of their low
boiling points. These vapors move through soil by the processes
of diffusion and dispersion. VOC's have a tendency to migrate
through porous regions. Due to their density and to
gravitational effects, these VOCs will move through deeper soils
and then enter ground water. When a sufficient concentration of
CC14 and chloroform are present, phase separation will recur and
the pure liquid will tend to be located in the lower regions of
the aquifer or above clay lenses, if such lenses are present.
Because these natural processes of diffusion and dispersion are
continuous, as long as the CC14 and chloroform remain in the
soil-gas, they will continue to move through the soil and into
11
-------
the ground water.
The continuous movement of the CC14 is indicated by the
data. For example, prior to the decommissioning of public supply
well M-3 in 1985, CC14 was present in M-3 at a concentration
ranging from 27 to 46 ppb. Since M-3 was taken out of service
and is no longer drawing CC14 from the source area, the presence
of CC14 has been noted in MW-23, a downgradient monitoring well.
CC14 and chloroform have been classified by EPA as probable
human carcinogens, based on animal studies. The potential for
carcinogenic risks is evaluated by estimating excess lifetime
cancer risks, that is, the incremental increase in probability of
developing cancer during one's lifetime, generally 70 years,
compared to the probability of getting cancer where there is no
exposure to contaminants. Based on the highest detected
concentration of CC14 and chloroform found in the ground water
sampled onsite at CW-1, the excess lifetime cancer risk for a
person who ingests two liters of such water per day for a
lifetime of 70 years is 3 X 10~^ which is greater than 1
increased cancer case in an exposed population of 1000. See
Table 5.
The level of CC14 contamination present in the ground water
and in soil gas above the water table necessitates a response
action at the Well Number 3 subsite to reduce the potential
risks to human health and to reduce further significant releases
of contaminants to the sole source aquifer.
Ground Water Contamination
Ground water at the subsite is found at a depth of
approximately 120 feet. The subsite is underlain by a sand and
gravel aquifer, having a saturated zone approximately 100 feet in
depth. This aquifer is the sole source of drinking water and is
used extensively for industrial and irrigation purposes. The
lateral flow in the aquifer has been found to be generally
eastward from the subsite. However, the potentiometric surface
map of the area indicates the direction of flow east of the
subsite is influenced by the regional east-southeast gradient.
The sand and gravel aquifer is underlain by thick deposits of
clay and shale. Depths to the clay/shale formations range from
200-220 feet.
Analyses of samples from Well M-3, taken between 1983 and
1985, have shown CC14 contamination (Table 3). M-3 is
approximately 4,500 feet downgradient from the source area.
12
-------
TABLE 3
Range of Concentrations of Volatile Organic Compounds in
Ground Water WELL NUMBER 3, Hastings, Nebraska
1983-1985
Concentrations in micrograms per liter (ug/1)
Parameter 4/83 5/83 4/85 9/85 12/85
CC14 27.1 31-46 22 26 32
Chloroform ND ND ND ND ND
^ ^ ^ m*^m ğ ^m ^m MB ^m ^ ğ ^ ^ Ğğ ^^ Ğğ ^ ^ Ğğ ^ ğ ^ğ ^ğ ^m ^^ Ğ> ^ ^ w ^ ğ ^ ^ ^ ^ ^ ĞH ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ĞM ^ ^ ^ Ğ _ ^ ^ ^ ^
Notes
- Data were obtained from the REM II Ground Water Investigation
Report for Hastings Ground Water Contamination, May 7, 1987,
and quarterly ground water sampling data
M-3 is located 4,500 feet east of the former grain storage
facility
Key: ND - not detected
In addition to the contaminants of concern,trichloro-
ethylene (TCE) also has been detected in the ground water at this
subsite. TCE is a contaminant of concern at other portions of
the Hastings Ground Water Contamination Site, but it was not
detected in the soils or soil-gas samples taken at the Well
Number 3 source area.
Ground water samples were collected from the monitoring well
located at the subsite (CW-1) and from monitoring wells located
downgradient from the subsite. The highest detected contaminant
concentrations of CC14 and chloroform were seen at well CW-1
which is screened in the shallow portion of the aquifer (120-140
ft.). As indicated in Table 4, CC14 is present not only in the
ground water onsite, but is also present in monitoring well MW-23
downgradient from the subsite. Table 4 also indicates that CC14
is not present in MW-12, a well northeast of the source area.
Table 1 indicates CC14 is not present in public supply wells M-6,
M-10, M-9 and M-llf which are downgradient of the source area.
13
-------
TABLE 4
Range of Concentrations of Volatile Organic Compounds
City of Hastings, Nebraska
1986-1989
EPA Monitoring Wells
Concentration in micrograms per liter (ug/1).
PARAMETER
CC14
Chloroform
1 , 1-Dichloroethene
(DCE)
Trans-1,2-
Dichloroethene
1 , 2-Dichloroethene
(Total)
Tetrachloroethene
(PCE)
Trichloroethylene
(TCE)
MW-3
ND
ND -
ND
ND
NA
ND -
4.0 M
81.0 -
130.0
MW-11
ND -
3.0 M
ND
ND
NA
ND
ND
ND -
11.0
MW-12
ND
ND
ND
NA
ND
ND
ND -
7.0
MW-23
ND -
8.0
ND
ND
NA
ND
ND -
3.0 M
ND -
70.0
CW-1
110.0 -
270.0
ND -
68.0
ND
NA
ND -
7.0
ND
ND
1,1,1- ND ND ND ND ND
Trichloroethane
(TCA)
Ethylene Dibromide NA NA NA ND ND -
(EDB) 0.088
NOTES:
Ground water data presented here for well MW-3 reflects data
collected from 1986 to 1989. Ground water data presented
for wells MW-11, MW-12, MW-23 and CW-1 were collected during
1988 and 1989.
M - the value indicated is below the quantification limit
but above the detection limit.
NA - parameter not analyzed.
ND - compound not detected.
Data were obtained from the REM II - Ground Water Evaluation,
Hastings Groundwater Contamination Site, Hastings, Nebraska,
May 7, 1987; and from EPA laboratory reports.
The above analyses were reported by EPA Labs and EPA
Contract Labs.
EDB reported in CW-1 was not confirmed in June, 1989 re-
sampling
14
-------
Soil and Soil-Gas Contamination
Soil sampling and soil-gas sampling were performed in 1988
and 1989 in order to better define zones with the highest
concentration of volatiles in the soils. Results of this
sampling, which is reported in the EE/CA, showed high levels of
contamination in the soil-gas and localized areas of
contamination. Figure 3 depicts the area where the highest
levels of CC14 in soil-gas have been detected. The action
selected in this document will reduce the potential for future
releases of CC14 and chloroform to the ground water by removing
the CC14 and chloroform from the unsaturated zone above the
ground water.
The results of the soil-gas analyses located the highest
levels of contamination at a depth of 80 to 120 feet (Figures 4
and 5), which is in the unsaturated zone directly above the water
table. Historical data indicates that the water table level has
receded 20 feet in the past 20 years. The contamination is
therefore located in an area that was once an aquifer which
produced large volumes of water.
FIGURE 4
SOIL-GAS SAMPLING LOCATIONS WELL NUMBER 3 SUBSITE
\
15
-------
SAMPLING RESULTS
Well No. 3 Subsite
CCI4 in Soil-Gas (ppm)
1 1 /
"""--I
14
8.9
34
22
160
120
41
0.2
11.0
*
-
"
ğ
m
0.4.
9.6
85
-50' <3'u
430
350
410
830
1100
-10°'1200
-17O*
MB
I
-
-
M
.
^
^*>
-lo1
-{bo-
^m
M
M
1
-
wm
m
13
26
8.1
110
140
120
150
0.2
-ISO'
-130'
FIGURE 5
Depth of borings shown in feet
16
-------
The levels of CC14 in soil-gas, as shown in Figure 5, pose a
potential health threat to users of ground water downgradient
from the source area.
RISK ASSESSMENT
A risk assessment has been conducted for two purposes:
1. to determine the likelihood that people who are exposed to
CC14 and chloroform known to be present at the subsite
will be adversely affected by that exposure; and
2. to characterize the nature of the effects such persons may
experience from exposure.
The risk assessment consisted of the evaluation of the toxic
properties of CC14 and chloroform and the conditions of human
exposure to them. This risk assessment has been based only on
exposure to the contaminants of concern and has not taken into
account other factors such as genetics, lifestyle habits, and
other environmental exposures.
Exposure Pathways
The likelihood of human exposure to high levels of CC14 and
chloroform contained within the soil-gas at the subsite is remote
as the high levels of these contaminants are located 40 feet
below the surface, depths greater than would normally be
encountered during typical excavation activities. Any risks
associated with human exposure to low levels of CC14 and
chloroform contained in the surface soils at the subsite is
likely to be minimal due to the dilution of the contaminants when
in contact with the atmosphere.
In contrast, the potential exposure pathways associated with
ground water contamination does present a potential threat to
human health. Potential exposure pathways include ingestion of
ground water, direct dermal contact with ground water, and
inhalation of contaminants released during use of contaminated
ground water. Persons potentially at risk of exposure to the
contaminants in ground water include users of private and
industrial wells downgradient from the site and customers who
depend on the public, water supply within the City of Hastings.
Carcinogenic Effects of CC14 and Chloroform
As discussed earlier in this document, the contaminants of
concern, CC14 and chloroform, have been identified by EPA as
probable human carcinogens, which, if ingested daily in high
enough doses over a lifetime, could elevate a person's cancer
risk. Excess lifetime cancer risks are determined by multiplying
the intake level by the cancer potency factor which is the
quantitative estimate of cancer risk due to ingestion of water.
These risks are probabilities that are generally expressed in
scientific notation (e.g., 1 X 10~6). An excess lifetime cancer
risk of 1 X 10~6 indicates that, as a plausible upper limit, an
17
-------
individual has a one in one million chance of developing cancer
as a result of site-related exposure to a carcinogen over a 70-
year lifetime under the specific exposure conditions at a site.
An assessment has been done of the risk associated with
ingestion by a 70 kilogram adult of two liters of water on a
daily basis over a lifetime of 70 years from CW-1, the
contaminated well at the subsite. The results of this baseline
risk assessment indicate that the risk of cancer to those who
ingest CW-1 well water, using the above-stated assumptions (2
liters /day /70kg /70 years), is approximately : 3 additional
cancers in a population of 1000 for CC14; 2 additional cancers in
a population of 100,000 for chloroform. This risk exceeds the
risk range that EPA considers protective of human health.
Extrapolations from animal studies indicate that the liver is the
organ at risk for developing cancer as a result of ingesting CC14
or chloroform, assuming 2 liters/day/70 kg/70years.
TABLE 5
Health Assessment Based on CW-1 Water Ingestion Exposure
Excess Lifetime Cancer Risk
EPA Carcinogenic Highest Detected Excess
Carcinogen Potency Factor Concentration Lifetime
Chemical Classification fma/ka/dav) fppb) Cancer Risk
CC1A B2
Chloroform B2
0.13
0.0061
700
120
3 X 10
2 X 10
-3
-5
Overall
3 X 10
-3
Notes: EPA's carcinogen classification scheme:
B2 = Probable human carcinogen on the basis of animal data
Source: Table 2-4, EE/CA for an Expedited Response Action for
Soil and Soil Gas Well Number 3 Subsite, July 24, 1989
citing Superfund Public Health Evaluation Manual,
U.S. EPA, 1986 and the Integrated Risk Information System
(IRIS), U.S. EPA, 1988. IRIS is a catalog of risk
assessment and risk management information designed
especially for federal, state and local environmental
health agencies as a source of the latest information
about Agency health assessments and regulatory decisions
for specific chemicals.
18
-------
Noncarcinogenic Effects of CC14 and Chloroform
An assessment has also been done of the noncarcinogenic
risks associated with ingestion of these contaminants.
Noncarcinogenic risk is determined by comparing the daily intake
of the contaminants to their reference dose (RfD), which is an
estimate of the daily exposure to the human population that is
likely to be without appreciable risk of harmful effects during a
lifetime. RfDs are reference points for gauging potential effects
of other doses. Therefore, doses less than RfDs are not likely
to be associated with any health risks but a clear conclusion
cannot be drawn that all doses below the RfDs are acceptable and
that all doses above the RfDs are unacceptable. RfDs are
expressed in units of milligram per kilogram per day. Estimated
intakes of the contaminants, if ingested from the ground water,
can be compared to the RfDs. RfDs are derived from human
epidemiological studies or animal studies, to which uncertainty
factors have been applied. These uncertainty factors help ensure
that the RfDs will not underestimate the potential for adverse
noncarcinogenic effects to occur. Table 6 indicates RfDs for
CC14 and chloroform.
TABLE 6
Reference Dose milligrams per kilograms per day
Water from CW-1
COMPOUND Critical Effect Highest Level Hazard Index RfD
CC14 Liver lesions 270 ug/1 11.0 0.007
Chloroform Fatty cyst form- 68 ug/1 0.196 0.01
ations in liver
Hazard Index is the daily intake divided by the reference
dose. A hazard index value greater than 1 indicates a
potential human health risk.
Environmental Risks
No threatened or endangered species or critical habitats
have been identified in or near the site. However, there is a
potential threat to the environment and to wildlife if source
control measures are not taken to prevent the release of the
contaminants into the ground water.
Conclusion
Because of the carcinogenic and noncarcinogenic risks to
human health associated with ingestion of ground water
contaminated with chloroform and CC14 at the levels found onsite
in CW-1, response action alternatives were developed to reduce
the potential for human exposure to contaminated ground water.
This response action selected will minimize the volume of
contaminated ground water which will migrate from the Well Number
3 subsite.
19
-------
SCOPE OF OPERABLE UNIT
This response action is an interim source control operable
unit and is consistent to the maximum extent practicable with
Section 300.68(c) of the National Oil and Hazardous Substances
Pollution Contingency Plan (NCP). This interim source control
operable unit is being implemented to protect public health and
the environment by controlling the migration and reducing the
volume of contaminants from the subsoils to the ground water.
The operable unit addresses known areas of contamination in the
sands and silts which overlie the aquifer. Future actions may
involve expansion of the response action or modification in the
design of the system being used. Based upon EPA's
investigations, the operable unit contains approximately 400
pounds of VOC's. This area is shown on Figures 3 and 5.
This interim action, by reducing the volume and controlling
the migration of contaminants, is fully consistent with all
future site work, including the ongoing ground water
investigations at the Hastings site. In addition, this action
will affect the costs of the final remedy by limiting the amount
of ground water that is likely to become contaminated from this
source.
The following are the key milestones for implementation of
the response action:
Approve Response Action (Execute ROD) September 1989
Initiate Response Design (Funding) November 1989
Initiate Response Action (Operational April 1990
Testing)
SUMMARY OF ALTERNATIVES
Response alternatives have been developed in order to meet
the objectives of CERCLA and, to the maximum extent practicable,
the NCP. The process used to evaluate alternatives for this site
is detailed in the EE/CA and is addressed briefly here.
The first step in the evaluation of alternatives was to
investigate technologies and determine which technologies may be
feasible. The technologies were then screened based on
effectiveness, implementability, and overall comparative cost.
The technologies that are applicable to the response action at
the subsite were then evaluated individually.
Based on this initial screening, response action
alternatives were identified for development and evaluation of
their ability to meet environmental laws and standards. This
interim action will be consistent with Section 121 (d) of CERCLA
which requires that remedial actions comply with applicable or
relevant and appropriate requirements or standards (ARARs) under
Federal and State environmental laws. Two of 3 alternatives
presented win the EE/CA in addition to the No Action alternative
20
-------
were further evaluated.
EVALUATION OF ALTERNATIVES
CERCLA and the NCP require that each alternative developed,
including the no-action alternative, be evaluated with respect to
two major criteria: overall protection of human health and the
environment and compliance with applicable or relevant and
appropriate environmental requirements. Seven additional
criteria are considered as a means to compare the alternatives.
These include:
- Long-term effectiveness;
- Reduction of toxicity, mobility or volume;
- Short-term effectiveness;
- Implementability;
- Cost;
- State acceptance; and
- Community acceptance.
Each alternative must be evaluated for the degree of onsite
and offsite protection required (and thus, to be provided) by the
actions involved, as part of the overall effectiveness.
Since this response action is an interim measure, two
alternatives will be compared and evaluated. These are, in
addition to the No-Action Alternative, Soil-Vapor
Extraction with Granular Activated Carbon Treatment of Air
Emissions and Soil-Vapor Extraction with incineration of air
emissions.
No-Action Alternative
The Agency has evaluated the no-action alternative for
source control. If the no-action alternative were selected, it
would be necessary to closely monitor the downgradient wells of
the public water supply system. This monitoring would identify
the wells with water that exceed the MCLs, but would not prevent
continued migration and would not assure availability of
alternate water supplies to users. Based on downgradient water
quality data and the high levels of contamination in the soil-
gas, the no-action alternative would not reduce migration of
contaminants and may permit the level of risk to increase due to
the amount of contamination present in the soils. Consequently,
neither on-site nor off-site protection would be achieved by this
alternative.
Another reason the no-action alternative is not viable is
that the long-term reliability of monitoring would decrease with
the passage of time and with distance from the site. In
addition, there would be no reduction of mobility, toxicity or
volume; therefore, the no-action alternative would create the
highest likelihood for future releases of hazardous substances to
the environment. Because hazardous substances are known to exist
in the soil-gas above the aquifer, the no-action alternative
21
-------
would not protect the ground water from further degradation.
Short-term costs associated with the no-action alternative
relate to the costs of monitoring the drinking water supply
system in Hastings. The frequency of this monitoring would
depend on the level of contamination found, with increased
frequency where high levels are found in the public supply
system. Additional wells would have to be installed in order to
properly monitor the movement of the plume. Further
investigations would be required to determine proper placement of
wells. Alternate water supply systems would have to be installed
or alternate treatment technologies would have to be implemented
in the case of high levels of contamination.
In-Situ Soil Vapor Extraction(SVE) and Treatment by Vapor Phase
Granular Activated Carbon (GAG) Adsorption
This alternative involves removing the contamination from
the soil-gas without excavation and subsequently treating the
vapor. This alternative would provide permanent removal and
destruction of contaminants from the soil-gas and, thereby, achieve
a reduction in mobility, toxicity and volume of contaminants and
impede their movement to the ground water. Human health and the
environment would be protected both on-site and off-site to the
extent that this response action would prevent the spread of
further contamination into the ground water. Further, as part of
the SVE process, the air emissions would be controlled.
A vapor extraction system enables VOCs to be removed from the
soil-gas by applying a vacuum and using a conventional industrial
blower and standard valving, piping and instrumentation. This
equipment is readily available, thus the SVE is an implementable
response action. Vacuum extraction has been used successfully in
full-scale operations for removing many types of VOCs found in
soils ranging from fine-grained silts to coarse-grained sand and
gravels. This alternative proposes that the extracted vapor
would be treated by a vapor phase activated carbon system, if
significant air emissions were to result from implementation of
this response alternative. The GAC filters would be replaced, if
necessary, and "spent" carbon would be transported off-site to an
approved treatment facility for regeneration or incineration (if
regeneration is not available). Any liquid generated from the
soil vapor process would also be treated with GAC. These liquids
would be disposed on-site when the MCLs for CC14 and chloroform
are reached.
The need for direct action was stressed in public comments
submitted to the Agency. This alternative is acceptable to the
community. The EPA and the state of Nebraska prefer the less
costly action alternative.
One of the characteristics of the SVE process is that it
immediately withdraws the contaminants. This response action
would therefore provide both short-term and long-term
effectiveness.
22
-------
An engineering calculation for the capital costs for this
response action was estimated to be $874,000, based upon a gas
extraction system of 19 extraction wells. The first year
operation and maintenance costs were $154,000. Details of this
calculation are set forth in the EE/CA.
Applicable, Appropriate, and Relevant Requirements (ARARs)
Regulations governing the transportation of hazardous
materials are applicable, relevant and appropriate to this
interim action. Therefore, transportation of the "spent" carbon
offsite will be done in compliance with regulations found in 49
CFR Part 107 promulgated pursuant to The Hazardous Materials
Transportation Act, 49 U.S.C. §1801 et. seq.
It is possible that the carbon used in the SVE system and
the subsequent treatment of the air emissions would become
contaminated, requiring its disposal as a hazardous
waste. Regulations governing the disposal of hazardous wastes
are therefore applicable, relevant, and appropriate. Disposal
would be in compliance with Sections 3002, 3003 and 3004 of the
Resource Conservation and Recovery Act, as amended (RCRA), 42
U.S.C. §6922, §6923, and §6924 and the regulations found at 40 CFR
Parts 262, 263, and 264. These statutes and regulations govern
the standards applicable to generators, transporters, and owners
and operators of hazardous waste treatment, storage, and disposal
facilities. These regulations require, among other things,
proper recordkeeping, reporting, and management of hazardous
wastes. Disposal of the "spent" carbon would also be consistent
with EPA's off-site policy which requires that hazardous wastes
disposed off-site as part of a remedial action would be taken to
a facility in compliance with RCRA.
The Occupational Safety and Health Act (OSHA), 29 USC §651
et. seq.. is legally applicable to this interim action. This law
regulates worker health and safety in the work place. The
regulations found at 20 CFR Part 1910 et. sea, are relevant to
this response action. These regulations protect health and
safety of workers at hazardous waste sites performing remedial
actions.
Estimated Time for Implementation
It is estimated' that an SVE system could be implemented at
this subsite within 9 to 18 months.
Treatment Goal
The goal of the SVE implementation is to remove the VOCs
known to be contained in the soil-gas directly above the aquifer.
The current engineering estimate of 400 pounds of VOCs in the
soil-gas at the sub-site contains uncertainty. Monitoring of the
SVE system for VOC removal and monitoring of the soil-gas within
the unsaturated zone above the aquifer will direct the
implementation and will determine the duration of the response
action.
23
-------
In-Situ Soil Vapor Extraction and Treatment by Incineration
This alternative involves removing the contamination from
the soils and treating the vapor. This alternative is similar in
design to the second alternative except that the vapor phase
emissions would be treated using incineration instead of GAC.
Incineration is a proven technology for treating VOC emissions.
An incinerator consists of a refractory-lined vertical
cylindrical vessel containing a bed of inert, granular materials.
Air is injected at the bottom of the vessel through a distributor
plate. Contaminated gases are injected above the bed.
Auxiliary fuel is also injected at this point. This equipment,
while costly, is readily available and therefore this response
action is implementable. This alternative would provide
permanent removal and destruction of contaminants and achieve a
reduction in mobility, toxicity and volume. Human health and the ,
environment would be protected both on-site and off-site to the ,
extent that this response action would prevent the spread of
further contamination into the ground water. Further, as part of the
SVE process, the air emissions would be controlled. Incineration
could achieve an overall VOC removal efficiency of over 99
percent if operating temperatures of 1880°F are achieved. Pilot
tests would be conducted for system design that would achieve the
level of destruction required at this site.
The need for direct action was stressed in public comments
submitted to the Agency. This alternative is acceptable to the
community. The EPA and the State of Nebraska prefer the less
costly action alternative.
One of the characteristics of the SVE process is that it
immediately withdraws the contaminants. This response action
would therefore provide both short-term and long-term
effectiveness.
An engineering calculation for the capital costs for this
response action was estimated to be $954,000, based upon a gas
extraction system of 19 extraction wells. The first year
estimated operation and maintenance costs were estimated to be
$213,000. Details of this calculation are set forth in the
EE/CA.
Applicable, Appropriate, and Relevant Requirements (ARARs)
The Occupational Safety and Health Act (OSHA), 29 USC §651
et. seq.. is legally applicable to this interim action. This law
regulates worker health and safety in the work place. The
regulations found at 20 CFR Part 1910 et. seq. are relevant to
this response action. These regulations protect health and
safety of workers at hazardous waste sites performing remedial
actions.
24
-------
Since the SVE process will capture the contaminants within
the soil-gas, the air to be burned within the incinerator will
contain hazardous waste, as defined in the RCRA regulations, 40
CFR Part 261 "Identification and Listing of Hazardous Waste."
Pursuant to Nebraska Environmental Protection Act Section 81-
1501 et. seq. regulations were promulgated. These regulations
found at Chapter 16 of Title 128 adopted RCRA regulations found
in 40 CFR Part 264 Subparts 0 Sections 264.340 through,264.351
concerning the proper operation of incinerators and are legally
applicable.
Estimated Time for Implementation
It is estimated that an SVE system could be implemented at
this subsite within 9 to 18 months.
Treatment Goal
The goal of the SVE implementation is to remove the VOCs
known to be contained in the soil-gas directly above the'aquifer.
The current engineering estimate of 400 pounds of VOCs- in the
soil-gas at the sub-site contains uncertainty. Monitoring of the
SVE system for VOC removal and monitoring of the soil-gas within
the unsaturated zone above the aquifer will direct the
implementation and will determine the duration of the response
action.
COMPARISON OF ALTERNATIVES
The no-action alternative is not a viable option because it
is not protective of human health and the environment. Of the
two action alternatives, both are protective of human health
and environment. Both are implementable; both would reduce
toxicity, mobility and volume of contaminants. The effectiveness
of both alternatives, short-term and long-term, are equal. The
degree of on-site and off-site protection is the same for both
alternatives. Both action alternatives are acceptable to the
community of Hastings. However, the only significant distinction
between the two action alternatives is cost effectiveness the SVE
alternative that utilizes GAC emission control is more cost
effective. The EPA and the state of Nebraska prefer the more
cost effective alternative.
Cost comparison data is shown in Table 7. These estimates
were based upon engineering judgments regarding implementability.
Clearly, soil vapor extraction using GAC is the more cost-
effective of the action alternatives.
Soil vapor extraction using GAC is also more cost-
effective as compared to the no-action alternative. By removing
the potential source of ground water contamination, the costs
associated with recovery and treatment of the contaminated ground
water are significantly reduced. Delay of source control action
will magnify the ground water contamination problem and thereby
cause total response action costs for this site to increase.
25
-------
TABLE 7
COST COMPARISON OF RESPONSE ACTION ALTERNATIVES
FOR CONTAMINATED SOIL GAS
WELL NUMBER 3 SITE
($ X 1,000)
Total First Year
Alternative Capital Costfa.cH O&M Cost (b.c)
No Action NA(e) NA
In-Situ Soil Vapor
Extraction and Treatment
by Vapor Phase Carbon
Adsorption 874 154
In-Situ Soil Vapor
Extraction and Treatment
by Incineration 954 213
Notes: (a) Estimate includes gas extraction system, air
treatment system, engineering design, construction
management and other contingency costs.
(b) Estimates include power costs, maintenance, labor,
monitoring of air and soils and contingency costs.
(c) For cost comparisons of alternatives, one year of
operation is assumed.
(d) Cost estimate based on the installation of a system
with 19 extraction wells. A system with fewer wells
would be expected to cost less.
(e) Cost estimates need to be developed for the long term
monitoring required, if this alternative is selected.
26
-------
SELECTED ALTERNATIVE
Based on available data and analysis conducted to date, the
EPA selected soil vapor extraction with GAC vapor treatment as
the most appropriate solution for meeting the goals of the source
control operable unit at the Well Number 3 subsite. The
characteristics of SVE that are considered most important are:
- The alternative provides protection to human health and
the environment from the potential threats associated with
no action;
- The alternative limits migration of contaminants to the
aquifer at the site;
- The alternative provides for compliance with applicable
laws and regulations; and
- The alternative is consistent with additional site actions
and will be compatible with the final site remedy.
The Regional Administrator retains the authority to make
changes in the scope and nature of source control actions to be
undertaken at this site. If new information or additional
environmental data warrants a change, then the impacts of the
suggested change will be reviewed to determine if any significant
departure from the selected alternative does in fact exist. Cost
impact of any proposed changes will be taken into account.
The design of the system will include a review of the data
produced by the Colorado Avenue Soil Vapor Extraction (SVE)
pilot. If needed, other data collection activities could be
incorporated into the design. Examples of necessary design data
could include the following:
1. Rate of gas withdrawal and air recharge;
2. Information to properly size the vacuum/air withdrawal
system components;
3. Radius of influence and other information to design the
final gas extraction well network;
4. Calculations of air emissions resulting from the soil
vapor extraction process;
5. Information to demonstrate the capability to control air
emissions and determine whether or not air monitoring
would be required during the cleanup phase;
6. Information to select and design the most cost effective
system for air emissions treatment; and
7. Information to design the gas monitoring well network.
27
-------
CLEAN-UP LEVELS
This interim action is being implemented for the purpose of
controlling contaminant migration, not restoration of the aquifer
to drinking water standards. Therefore, no cleanup levels are
being established at this time. The vapor extraction system will
initially operate under controlled conditions to provide for
collection and analysis of operational data. The data will be
used to refine final design information and to establish
effectiveness of the vapor extraction system. Cleanup
effectiveness will be evaluated based on volume of contaminants
recovered from the soils. Review and decision-making regarding
cleanup levels will be closely coordinated with the state of
Nebraska. Since the potential threat existing at the site is
related to inhalation and ingestion of contaminated drinking
water rather than from a direct contact threat, the clean up
levels for soil and ground water can be addressed later.
As previously stated, recovery of volatiles by SVE will be
less costly than treating large volumes of contaminated ground
water at a future date. Therefore, the volume of volatile
contaminants recovered will be one measure of success of the
selected remedy. Ground water monitoring is expected to show a
decreased concentration of contaminated ground water migrating
from the site. These monitoring data will be direct measures of
success of the selected remedy. The anticipated result is that
the duration of any long-term actions will be decreased by this
remedy.
OPERATION AND MAINTENANCE
The recommended alternative requires a certain degree of
annual operation and maintenance (O&M) activity to ensure proper
operation of the system and compliance with environmental laws
and regulations. The costs of O&M will depend on volume of
contaminants recovered and the size of the completed vapor
extraction system. An O&M plan will be developed during design
of the system after the initial phase of operation and testing.
A ground water monitoring plan will also need to be
developed and implemented to demonstrate reduced migration of
contaminants in the ground water.
FUTURE ACTION
Ground water monitoring wells downgradient from the site
will continue to be sampled and a technical approach for plume
management will be developed. Agency decision-making regarding
ground water treatment will be discussed with the state of
Nebraska prior to preparation of a Record of Decision for ground
water treatment.
28
-------
STATE ROLE
The state of Nebraska's Department of Environmental Control
has reviewed the various alternatives and has indicated its
concurrence with the selected action. The state has also
reviewed the EE/CA and concurs with the selected action for the
Well Number 3 Subsite of the Hastings Ground Water Contamination
Site.
29
------- |