United States
Environmental Protection
Agency
Office ol
Emergency and
Remedial Response
EPA/ROO/R07.90/039
September 1990
Superfund
Record of Decision;
Waverly Ground Water Contamination,
NE
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50272.101
REPORT DOCUMENTATION 1" REPORT NO. 2. :L RecIpi8nt'. AcC88810n No.
PAGE EPA/ROD/R07-90/039
4. 11118 IIId ..... 5. A8part D...
SUPERFUND RECORD OF DECISION 09/26/90
Waverly Ground Water Contamination, NE
Remedial Action - Final I.
First
7. Auth«(.) I. PwfonNng 0r1I1niZII1Ion A8IM. No.
t. PerfonNng Orglinlzatlon NInw end.... 10. ProJIcIITl8IuWork UnI1 No.
11. Con1r~C) or GnnI(O) No.
(C)
(a)
12. Sponeor1n9 OrgaNza'" ..... end AddNU 13. Type 01 A8part . PerIod Co-.ct
U.S. Environmental Protection Agency 800/000
401 M Street, S.W.
Washington, D.C. 20460 14.
15. Suppll......18ry NotH
11. Ab81rKt (Umlt: 200 wordl)
The Waverly Ground Water Contamination site is in Waverly, Lancaster County, Nebraska.
At this municipally owned site, the ground water aquifer provides 100 percent of the
drinking water for the community of approximately 2,000 people through the municipal
water system. Between 1952 and 1974, a Federal grain facility, located on a portion of
the site, was the source of ground water contamination. From 1955 to 1965, the fumigant
80/20, composed of 80 percent carbon tetrachloride and 20 percent carbon disulfide, was
used onsite on stored grain. Chloroform is a by-product of carbon tetrachloride
production and may also have been present on site. In 1982, contamination was detected
in Public Water Supply Well (PWS) Numbers 1 and 3. PWS 3 was removed from service and
four additional wells were installed outside the known area of contamination. In 1988,
EPA began contaminant treatment at the site by installing an air stripping system, in
conjunction with ground water pumping and treatment and soil vapor extraction systems.
The contaminants of concern affecting the soil and ground water are VOCs including
carbon tetrachloride and chloroform.
The selected remedial action for this site includes continued operation and maintenance
of the ground water air stripping system and the soil vapor extraction system; ground
(See Attached Page)
17. Docum8nI An8/y8I8 .. DiI8CItptanI
Record of Decision - Waverly Ground Water Contamination, NE
First Remedial Action - Final
Contaminated Media: soil, gw
Key Contaminants: VOCs
b. IcI8ntItI8r8/Open-EndIcI T-
Co COSATI Fl8Wroup
18. Avlil8blllty 8.....,.,., 18. SecwIty CI- (TIll. Report) 21. No. 01 P8gM
None 42
2G. S8cuItty CI88 (Thil Page) 22. PrIc8
None
(See ANSI-Z3I.II)
SeeIn81rUd- on Re-
(For-'Y NT1S4I)
~ofC:-
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EPA/ROD/R07-90/039
Waverly Ground Water Contamination, NE
First Remedial Action - Final
Abstract (continued)
water monitoring to delineate the magnitude and extent of contamination; evaluation of
the construction of PWS 3 to explain the contamination in this well; sampling existing
and new monitoring wells; development of a ground water flow and transport model to
determine the correct pumping rate for the existing ground water ~xtrac~ion well, and
investigation of the potential uses for the treated water discharged offsite. The
estimated present worth cost for this remedial action is $3,550,000, which includes an
annual O&M cost of $451,000 for 15 years.
PERFORMANCE STANDARDS OR GOALS: Soil gas cleanup levels for VOCs will be reduced to
the performance criteria level of 6.5 ug/kg calculated for the site. Soil levels were
below the calculated cleanup levels of 1.1 mg/kg and 1.7 mg/kg for carbon
tetrachloride and chloroform, respectively. The treated water discharge will meet
State NPDES permit levels of 5.0 ug/l for carbon tetrachloride and 3.8 mg/l for
chloroform. Ground water cleanup levels will meet State MCLs including carbon
tetrachloride 5.0 ug/l (MCL) and chloroform below 3.8 ug/l (MCL).
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RECORD OF DECISION
DECLARATION
WAVERLY GROUND WATER CONTAMINATION SITE
WAVERLY, NEBRASKA
Prepared by:
THE ENVIRONMENTAL PROTECTION AGENCY
REGION VII
KANSAS CITY, KANSAS
September 1990
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DECLARATION FOR THE RECORD OF DECISION
~ NAME AW2 LOCATION
Waverly Ground Water Contamination Site
Waverly, Nebraska
STATEMENT Ql BASIS AHQ PURPOSE
This decision document represents the selected remedial
action for the Waverly Ground Water Contamination Site in
Waverly, Nebraska, chosen in accordance with the Comprehensive
Environmental Response, compensation and Liability Act of 1980
(CERCLA) as amended by the Superfund Amendments and Reauthoriza-
tion Act of 1986 (SARA) and, to the extent practicable, the
National oil and Hazardous Substances Pollution Contingency Plan
(NCP) .
This decision is based upon the contents of the
Administrative Record for the Waverly Ground Water Contamination
Site.
The United States Environmental Protection Agency and the
State of Nebraska agree on the selected remedy. The State of
Nebraska concurs with this Record of Decision.
ASSESSMENT Ql THE ~
Actual or threatened releases of hazardous substances from
this Site, if not addressed by implementing the response action
selected in this Record of Decision (ROD), may present an
{mminent and substantial endangerment to public health, welfare,
or the environment.
DESCRIPTION Q[ IRE REMEDY
This final remedy addresses the principal threat through the
remediation of ground water and soil contamination by eliminating
or reducing the risks posed by the Site through treatment.
The major components of the selected remedy include:
Extraction of the contaminated ground water using the
existing ground water extraction well;
Onsite treatment of the extracted ground water using
existing air strippers;
Active soil gas extraction using existing system of
soil vapor extraction wells; and,
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continued investigation of the contaminant plume and
monitoring of the systems to determine the
effectiveness of the remedy.
These response actions would prevent future ingestion of
hazardous substances by containing the contaminated ground water
plume, removing the contamination, and restoring the aquifer to
acceptable goals for unrestricted use.
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the
environment, complies with Federal and state requirements legally
applicable or relevant and appropriate to the remedial action,
and is cost-effective. This remedy utilizes permanent solutions
and alternative treatment technologies to the maximum extent
practicable and satisfies the statutory preference for remedies
that employ treatment that reduces toxicity, mobility, or volume
as a principal element.
A review will be conducted within five years after
commencement of remedial action to ensure that the remedy
continues to provide adequate protection of human health and the
environment.
71Z-
~ ~o ris Kay
1// R gional Administrator
U.S. Environmental Protection
Region VII
#;~~
Agency
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1
STATE
OF
NEBRASKA
DEPARTMENT OF ENVIRONMENTAL CONTROL
KAY A. ORR
GOVERNOR
DE~NIS GRAMS
DIRECTOR
September 14. 1990
Mr. Morris Kay
Regional Administrator
EPA Region VII
726 Minnesota Avenue
Kansas City. KS. 66101
\.L.;I.... . --
SEP ? '~ 19So]
Ii£GJONAL ADM/NISTRATQ~
Dear Mr. Kay:
Upon consideration of the Administrative Record and the draft Record of
Decision (ROD), the Nebraska Department of Environmental Control (NDEC)
concurs with the Environmental Protection Agency's remedy selection for the
Waverly Ground Water Contamination Site.
NDEC understands that the remedy will remediate the contaminated ground
water through ground water extraction and treatment and the unsaturated zone
through active soil vapor extraction. In addition. NDEC understands that
additional investigation will be performed to ensure that remediation of all
contaminated areas above the action levels. defined in the draft Record of
Decision. will be achieved.
The selected remedy presented in the draft ROD will meet all state
requirements.
NDEC appreciates the opportunity for involvement in the remedy selection
process.
Sincerely.
i'~ - ~
~.-~ L,~
Dennis Grams. P.E.
IV/rm
RECEIVED
SEP 1 " 1990
"' SMD r, ~ CII..llN
(ltlAtt,
P. O. BOX 98921. LINCOLN. NEBRASKA 68509-8921. PHONE (401) 471-2186
AN EOl'Al OPPORTlr~"TY'.4.FTIR"-t.UI\'E .4.CTIO'loi EMPLOYER
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RECORD OF DECISION
WAVERLY GROUND WATER CONTAMINATION SITE
WAVERLY, NEBRASKA
Prepared by:
THE ENVIRONMENTAL PROTECTION AGENCY
REGION VII
KANSAS CITY, KANSAS
September 1990
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I.
II.
III.
IV.
V.
VI.
VII.
VIII.
IX.
X.
XI.
XII.
TABLE OF CONTENTS.
SITE NAME, LOCATION, AND DESCRIPTION............PAGE 1
SITE HISTORY AND ENFORCEMENT ACTIVITIES.........PAGE 2
HIGHLIGHTS OF COMMUNITY PARTICIPATION...........PAGE 3
SUMMARY OF SITE CHARACTERISTICS.................PAGE 4
SCOPE OF RESPONSE ACTION........................PAGE 5
DESCRIPTION OF THE INTERIM REMEDY...............PAGE 5
APPLICABLE OR RELEVANT AND APPROPRIATE
REQUIREMENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PAGE 7
SUMMARY OF SITE RISKS...........................PAGE 8
DESCRIPTION OF ALTERNATIVES.....................PAGE 11
SUMMARY OF COMPARATIVE ANALYSIS OF
ALTERNATIVES................................... . PAGE 13
THE SELECTED REMEDY............................. PAGE 16
STATUTORY DETERMINATIONS........................PAGE 17
XIII. DOCUMENTATION OF SIGNIFICANT CHANGES............PAGE 20
FIGURE 1
FIGURE 1
TABLE 1
TABLE 2
...
(continued)
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SECTION I.
SITE NAME, LOCATION, AND DESCRIPTION
The waverly Ground Water contamination Site is located in
Lancaster County in southeastern Nebraska in and near the City of
waverly. waverly is located (Figure 1) along State Highway 6,
approximately 10 miles northeast of Lincoln, Nebraska. The site
is in the northwest portion of Waverly. A former Commodity
Credit corporation Federal grain facility was located on a
portion of the Site. This facility was located along the south
side of Oldfield Street just west of North 141st Street.
The population of the City of Waverly is approximately
2,000. The land immediately north vf the Site is primarily used
for agriculture, and the land use immediately to the south of the
Site is residential. The City of Waverly obtains 100 percent of
its drinking water supply from the municipal water system which
taps the ground water aquifer.
Analytical results from water samples taken from local
public and private drinking water wells in June 1984 showed
concentrations of carbon tetrachloride as high as 3,120
micrograms per liter, and chloroform concentrations as high as
37 micrograms per liter. The former Federal grain facility has
been identified as the source of contamination based upon evalua-
tion of ground water data, soil gas analysis, and past grain
fumigation practices. A grain fumigant, named 80/20, was used at
the facility. The 80/20 fumigant was composed of 80 percent
carbon tetrachloride and 20 percent carbon disulfide.
The Environmental Protection Agency conducted an expedited
response action to control the source and spread of contamination
at the Site. A ground water extraction and air stripping system,
which removes contaminants from the aquifer and helps to contain
the spread of the contaminated ground water plume, removes and
treats the contaminated ground water. An active soil gas
extraction system removes the contaminants from the soils and
acts to control the transfer of contaminants from Site soils
above the water table to the ground water. The systems went
into operation in February 1988 and have been operating effec-
tively since then. As of March 1990, the highest concentrations
of carbon tetrachloride and chloroform at any of the monitoring
points at the site were 165 micrograms per liter and 6.5 micro-
grams per liter, respectively, in the influent water to the
system from the ground water extraction well. "The combined air
emission rate from the air stripping and vapor extraction systems
has dropped from initial values of 0.051 grams per second to the
March 1990 value of 0.0011 grams per second. The emission rates
include both carbon tetrachloride and chloroform~
Surface runoff from the site enters local ditches and flows
west to Salt Creek. The Site is underlain by about 13 feet of
loess, which is over 80 feet of sand in two layers separated by
1
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approximately five feet of clay with limestone bedrock occurring
at a depth of about 100 feet. The depth to ground water in the
area of the site is between 10 and 20 feet. The major surficial
aquifer in the site area is the Waverly aquifer, and five of the
City of Waverly's supply wells are developed in this aquifer.
The directio~ of ground water flow in the Waverly aquifer is to
the north-northwest with an estimated flow velocity of 90 to
150 feet per year.
SECTION II.
SITE HISTORY AND ENFORCEMENT ACTIVITIES
The Commodity Credit Corporation, a part of the U. S.
Departm~nt of Agriculture, operated a Federal grain facility at
the Site between 1952 and 1974. The facility consisted of grain
storage structures (approximately 100 bins and 13 quonset huts)
on concrete foundations. The fumigant 80/20 was used at the
facility between approximately 1955 and 1965. The fumigant is
reported to have been composed of 80 percent carbon tetrachloride
and 20 percent carbon disulfide. Chloroform also may have been
present in 80/20 as a by-product of the production of carbon
tetrachloride.
Since 1975, the former Federal grain facility property has
been owned by Lancaster County which operates a district office
and maintenance facility on the premises. Parts of the Site are
covered by piles of road maintenance and construction materials
and graveled parking areas. Some of the original grain storage
foundations still exist at the Site.
The Environmental Protection Agency sampled the Waverly
municipal water system in July 1982 as part of a nationwide
survey. The analytical results indicated contamination of Public
Water Supply Well Numbers 1 and 3 with carbon tetrachloride and
chloroform at concentrations of. up to 200 micrograms per liter
and 7.5 micrograms per liter, respectively. Subsequent sampling
of Well Number 3 in 1983, 1984, 1985 and 1986 has shown high
levels of carbon tetrachloride and chloroform. The Site was
placed on the National Priorities List of sites requiring long-
term remedial action in October 1984.
Subsequent to the discovery of contamination, Public Water
Supply Well Numbers 1 and 2 were relegated to "standby" status,
and Well Number 3 was removed from service. Between 1982 and
1987, four additional Public Water Supply Wells were installed
south of the site. Two of these wells are two miles southwest of
town, which is outside the study area for the Site and outside
the known extent of the contaminant plume associated with the
Site.
In 1985, forty-seven wells near the Site were sampled for a
wide range of parameters including volatile organics, semi-
volatile organic compounds, metals, and pesticides as part of the
2
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characterization of the Site. Analysis of samples from Public
Water supply Well Number 3 again showed significant
contamination. The contaminants that were found in this well at
significant concentrations were carbon tetrachloride and
chloroform. Iron, manganese, and selenium were found to exceed
National Drinking Water Standards in some of the ground water
samples taken during the 1985 study. The iron and manganese
standards are considered secondary drinking water standards and
are intended to provide guidelines on aesthetic qualities such as
taste, odor, or color. The selenium standard is considered to be
a primary drinking water standard and is set to protect public
health. These contaminants have not been detected at concentra-
tions above the standards in the public water supply or private
wells sampled to monitor the response action systems at the Site,
and they are not considered contaminants of concern for the site.
In May 1986, the Environmental Protection Agency developed
an Engineering Evaluation Cost Analysis Report outlining an
expedited response aCT1n,. Tn~ r.espons~ action outlined included
pump and treat using air stripping technology and soil gas
extraction. Design of the systems was completed in May 1987, and
a public meeting was held in Waverly with the Mayor and City
Council to receive their comments on the response action systems.
The Environmental Protection Agency began operation of the
current expedited response action systems at the Site in
February 1988. A compliance Aqreement between the Commodity
Credit Corporation of the U. S. Department of Agriculture and the
Environmental Protection Agency went into effect in May 1988. In
June 1988 the Commodity Credit corporation took over the
operation and maintenance of the response action. The Commodity
Credit Corporation of the Department of Agriculture is the only
potential responsible party for the site and will implement the
actions described in this Record of Decision.
SECTION III.
HIGHLIGHTS OF COMMUNITY PARTICIPATION
The Feasibility Study and proposed Plan for the waverly
Ground Water Contamination site were released to the public in
JulY.1990. . The Administrative Record file, which includes these
documents, was made available to the public at information repos-
itories maintained at the Waverly City Hall, in Waverly,
Nebraska, and the Environmental Protection Agency Docket Room, in
Kansas City, Kansas. Notice of the availability of these docu-
ments for review and comment was published in ~ Waverly News
and ~ Lincoln Journal on August 9, 1990. The public comment
period ended September 7, 1990. In addition, a public meeting
was held in Waverly on August 20, 1990 to present the results of
the Feasibility Study and the preferred alternative as presented
3
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in the Proposed Plan for the Site. All comments received by the
Environmental Protection Agency prior to the end of the public
comment period, including those expressed verbally at the public
meeting, are addressed in the Responsiveness Summary.
SECTION IV.
SUMMARY OF SITE CHARACTERISTICS
Carbon tetrachloride and chloroform contamination have been
found on and off the Waverly Site. Onsite, the contamination was
found in the soil, soil gas, and ground water. Offsite, carbon
tetrachloride and chloroform were found in ground water. The
contamination of the Waverly aquifer as described below is the
principal threat associated with this Site. The Waverly aquifer
is a source of drinking water. for the City of Waverly.
Soil contamination occurs primarily in the north central
portion of the Site. The maximum concentrations of carbon
tetrachloride and chloroform were 400 micrograms per kilogram and
44 micrograms per kilogram, respectively. Soil gas contamination
was measured in all the vapor extraction system wells tested.
The maximum concentrations of carbon tetrachloride and chloroform
were 5,926 parts per million and 1,800 parts per million, respec-
tively. Ground water contamination onsite was found in all four
shallow wells screened at the top of the aquifer (13 to 28 feet).
Maximum concentrations of carbon tetrachloride and chloroform at
levels of 940 micrograms per liter and 140 micrograms per liter,
respectively, were found in Monitoring Well Number lA, located on
the northern edge of the Site. contamination was not found in
the deeper wells onsite (50 to 80 feet).
Ground water contamination was also found to the north of
the site in monitoring well Number 5B, the Hedrick South Well,
and Public Water Supply Well Number 3. Maximum concentrations of
carbon tetrachloride and chloroform in Monitoring Well Number 5B
were 260 micrograms per liter and 20 micrograms per liter,
respectively. Monitoring Well Number 5B is screened from a depth
. of 45 to 50 feet. Carbon tetrachloride concentrations in the
Hedrick south and Public Water Supply Well Number 3 were
14 ~icrograms per liter and 9 micrograms per liter, respectively:
however, the depths of the screened intervals are not known in
these wells. No volatile contaminants were detected in any of
the upgradient wells located south of the Site. This ground
water characterization is based on September 1987 data.
contamination occurs near the top of the aquifer onsite and
in the lower part of the upper portion of the Waverly aquifer to
the north of the Site. The areal extent of the ground water
contamination in the vicinity of the Site cannot be defined on
the basis of the existing monitoring well network. Additional
clustered monitoring wells should be installed north and north-
west of the Site to determine the extent of the plume in these
directions.
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The ground water extraction and air stripping system and the
soil gas vapor extraction systems have now operated for more than
two years. January 1990 data indicated that the only wells still
showing contamination are Monitoring Well Number 2A onsite and
the Hedrick south well offsite with concentrations of carbon
tetrachloride at 9 micrograms per liter and 24 micrograms per
liter and chloroform concentrations at 7 micrograms per liter and
9 micrograms per liter, respectively. Public Water Supply Well
Number 3 did not contain detectable levels of either compound.
SECTION V. SCOPE OF RESPONSE ACTION
The principal threat at the Site is the carbon tetrachloride
and chloroform contamination in the Waverly aquifer which is used
by the City of Waverly as a source of drinking water. The
selected response actions will address the principal threat
through the remediation of contaminated ground water as well as
the remediation of contaminated soils. Uncontaminated drinking
water is being provided to the City of Waverly through the
municipal wells currently in operation. Past and ongoing actions
taken at the Site are also contributing to the protection of the
City's water supply and the cleanup of the Site by removing
contaminants from the soil and grounJ W'd t~L., preventing the
migration of the plume of contamination in the ground water to
the current drinking water supply wells, and taking the
contaminated City wells out of service. However, if the plume of
contaminated ground water was allowed to migrate to the current
supply wells or the supply wells now out of service or on standby
were activated, a threat of exposure to contaminated ground water
would exist. To address the potential risks from such exposure,
the following remedial action objectives were identified;
.
Prevent potential exposure to contaminated ground
water;
.
Protect uncontaminated ground water for future use
by preventing further migration of the contaminated
ground water plume; and,
Restore contaminated ground water for future use as
drinking water by reducing the carbon tetrachloride
and chloroform concentrations below health based
criteria.
.
SECTION VI. DESCRIPTION OF THE INTERIM REMEDY
In February 1988, the Environmental Protection Agency began
operating expedited response action systems at the Waverly Ground
Water Contamination Site. The air stripping system, in conjunc-
tion with the ground water extraction system, was designed to
provide an effective method for remediating ground water contarni-
5
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nation. The vapor extraction system was designed to provide a
method of source control that would remove contamination located
in the soils between the ground surface and the water table and
remove contamination vOlatilizing off the ground water table.
The air stripping system is designed to accept a flow rate
of 400 gallons per minute from the ground water extraction well
containing concentrations of carbon tetrachloride and chloroform
of up to 4,000 micrograms per liter and 360 micrograms per liter,
respectively, and to remove 99.9 percent of the contaminant
concentration. Water is pumped to a flow distributor at the top
of the stripper and cascades down through a bed of inert packing
material. Clean air enters the bottom of the column and is
driven upward through the packing exiting at the top of the
column. The volatile contaminants are transferred from the water
to the air resulting in treated water with very low volatile
concentrations and air with elevated levels of volatiles. The
air and volatile contaminants exit the system through a stack
which is 41 feet above grade, and the emissions from the stack
should not exceed the performance standard of 0.147 grams per
second. The treated effluent water from the air stripper is
discharged to the ditch north of the Site. The effluent water
flows west via drainage ditches to Salt Creek. The maximum
permitted contaminant concentrations in the discharge water are
regulated by the National Pollutant Discharge Elimination System
(NPDES) as set by the Nebraska Department of Environmental
Control (NDEC). The effluent standards are 6.95 micrograms per
liter and 5.0 micrograms per liter for carbon tetrachloride and
chloroform, respectively. The discharge water is sampled
monthly, as required by the permit.
The ground water extraction well was installed on the north
edge of the site in the area of greatest ground water contamina-
tion. The well is screened in two intervals: 19 to 34 feet, and
39 to 49 feet below the ground surface. The well is designed to
have a zone of influence between 1,000 and 1,400 feet when
pumping at 150 gallons per minute. Public Supply Well Number 3
and the Hedrick south well are approximately 900 and 1,200 feet
from the ground water extraction well, respectively. Carbon
tetrachloride concentrations in Public Water Supply Well Number 3
have declined from 9 micrograms per liter in October 1987 to
below detection limits currently. The Hedrick well is still
contaminated with carbon tetrachloride concentrations ranging
from 20 to 50 micrograms per liter. However, the Hedrick south
well is an open hand-dug well in the basement of the residence
and its validity as a monitoring point is questionable. The
installation and sampling of monitoring wells in the area near
the Hedrick south property to address this uncertainty will be
done as part of this remedial action. As of January 1990 the
only monitoring well still showing detectable concentrations of
contaminants is monitoring well number 2A which is a shallow well
onsite.
6
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The vapor extraction system consists of 17 vapor extraction
wells installed in the soil above the water table at depths
between 27 and 29 feet with the lower 15 to 20 feet screened. A
blower, sized for 160 cubic feet per minute air flow rate,
creates a vacuum in the vapor extraction wells. Air is drawn
through the soil which induces the transfer of easily volatilized
compounds from solution to the vapor phase. The vapors are then
drawn into the vapor extraction wells and exit the system at the
top of the air stripping towers (41 feet above grade).
In tests, the radius of influence for a vapor extraction
well is about 100 feet. The combined contaminant emissions from
the vapor extraction system and the air stripping system should
not exceed the 0.147 grams per second performance standard.
Performance criteria have been established for combined
volatile organic compound air emissions, ground water, surface
water, soil, and soil gas at the Site to protect human health and
the environment. The criteria include the compliance points,
action levels, monitoring frequency, and compliance period for
each media. The performance criteria are summarized in Tables 1
and 2. These performance criteria have been incorporated in the
Compliance Agreement between the Environmental Protection Agency
and the Commodity Credit Corporation of the U. S. Department of
Agriculture and will be incorporated in any future agreements
between these agencies.
SECTION VII.
APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
In making decisions on site remedies, the Environmental
Protection Agency identifies the requirements of regulations,
statutes criteria and standards which would be applicable to the
remedial action taken at a site or if not applicable, then rele-
vant and appropriate to the actions taken at a site. The
applicable or relevant and appropriate requirements for the
Waverly Site' are as follows:
1.
The Safe Drinking Water Act (40 U.S.C. 1300) National Primary
Drinking Water Standards (40 C.F.R. Part 141) establishes
health-based standards for public water systems by
establishing Maximum Contaminant Levels (MCLs). The MCL for
carbon tetrachloride is five micrograms per liter in drinking
water, and the MCL for chloroform is 100 micrograms per liter
for the sum of the concentrations of a set of trihalomethane
compounds which include chloroform;
The Clean Water Act (33 U.S.C. 11251 et seq.) Water Quality
criteria (40 C.F.R. Section 131) sets criteria for water
quality based on toxicity to aquatic organisms and human
health:
2.
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"
J.
The Clean Air Act (42 U.S.C. S7401 et seq.) establishes air
emission requirements:
4.
state of Nebraska Ground Water Quality Standards and Use
Classification (Title 118) establishes standards for ground
water and includes an antidegradation provision:
state of Nebraska Air Pollution Control Rules and Regulations
(Title 129) establishes emission rates for which sources must
obtain construction permits and report emissions annually.
The applicable or relevant and appropriate emission rates are
as follows:
5.
(a) 15 or more pounds of volatile organic compounds in
any hour of operation of 100 or more pounds of
volatile organic compounds in any consecutive
24-hour period (Chapter 4 004.01E): and,
(b) 2.5 tons/year or more of any toxic air pollutant
(Chapter 4 004.01G). Toxic air pollutants are
listed in Appendix III of Title 129.
6.
The Occupational Safety and Health Act (29 U.S.C.
S651 et seq.) regulates worker health and safety:
The State of Nebraska Rules and Regulations Pertaining to the
Issuance of Permits Under the National Pollutant Discharge
Elimination System (Title 119) establishes permitting, moni-
toring, and reporting requirements for discharges from point
sources; and,
7.
8.
Nebraska Department of Health Regulations Governing Public
Water Supply Systems (Title 179, Chapter 2) lists drinking
water standards and requirements for permitting, operating,
monitoring, and reporting for public water supply systems.
SECTION VIII.
SUMMARY OF SITE RISKS
The risk evaluation contained in the Site Characterization
Report (February 1988) assessed the potential hazards to public
health that may result from the release of hazardous substances
or contact with hazardous substances found at the Site. The risk
assessment consisted of the evaluation of the potential health
effects and environmental fate of the contaminants of concern
found at the Site. These contaminants have been identified as
carbon tetrachloride and chloroform. The risk assessment consid-
ered carcinogenic potential and daily exposure based on maximum
concentrations detected to estimate incremental lifetime cancer
risks.
The contaminants of concern, carbon tetrachloride and
chloroform, have been classified by EPA as "B2" or probable human
8
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carcinogens. The B2 classification includes hazardous substances
for which there is sufficient evidence of increased incidence of
cancer from animal studies and inadequate evidence or no data
from human epidemiologic studies. Th~ level of risk is expressed
in scientific notation, e.g., 1 X 10- , and represents the
probability or range of probabilities of developing additional
incidence of cancer under the prescribed exposure cond~tions.
For example, an excess lifetime cancer risk of 1 X 10- indicates
that, as a plausible upper bound, the risk of developing cancer
as a result of site-related exposure to a carcinogen over a
70-year lifetime under the specific exposure congitions is one in
one million. cumulative risk levels of 1 X 10- to 1 X 10-4 can
be used to determine the "environmental significance" of the risk
incurred and are used as a target range when evaluating remedial
actions at a site or the need for reiedial actions at a site. A
cumulative risk greater than 1 X 10- is considerid to be
unacceptable. Risks between 1 X 10-6 and 1 X 10- are cons~dered
to be potentially unacceptable, and risks less than 1 X 10- are
considered to be insignificant. These classifications are not
absolute and are considered only to put site risks into
perspective.
The exposure pathways considered in the risk evaluation
were: worker and resident exposure to soil through ingestion and
direct contact: exposure to contaminated ground water through
ingestion: and, exposure to air emissions generated by the air
stripping and vapor extraction systems through inhalation. Since
the likelihood of human exposure to significant levels of carbon
tetrachloride and chloroform contained within the soil gas at the
Site is remote, this route was not considered.
1. SOIL
The incremental lifetime cancer risk for onsite workers
through ingestion and direct contact with Site soils c9ntaminated
with carbon. tetrachloride and chloroform is 0.57 X 10-. This
number is based on 20 years of five-day weeks during the outdoor
work season and maximum soil concentrations for carbon tetrachlo-
ride and chloroform similar to those at the Site.
. The incremental lifetime cancer risk for onsite residents
through ingestion and direct contact with Site soils c9ntaminated
with carbon tetrachloride and chloroform is 4.86 X 10-. This
number is based on 70 years of seven-day weeks and maximum soil
concentrations of 0.40 milligrams per kilogram and 0.051 milli-
grams per kilogram of carbon tetrachloride and chloroform,
respectively.
Both of the above ~ancer risk levels are less than the one
in one million (1 X 10- ) additional cancer risk and would,
therefore, be classified as insignificant.
9
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2. GROUND WATER
The excess lifetime cancer risk associated with the inges-
tion by a 70 kilogram adult of two liters. of water on a daily
basis over a lifetime of 70 years from Public Water Supply Well
Number 3 (the most highly contam~nated public well at the Site --
now out of service) is 1.2 X 10-. This number is the sum of the
risks from the ingestion of carbon tetrachloride and chloroform.
The risk for each compound is the product of the intake level
that is based on the highest concentration found in Public Water
Supply Well Number 3, which is 3,120 micrograms per liter and
810 micrograms per liter for carbon tetrachloride and chloroform
respectively, and carcinogenic potency factors which are 0.13 and
0.0061 respectively. This risk estimate indicates that, as a
plausible upper bound, 12 additional cancers may occur in a
population of 1,000; which exceeds the risk range that EPA
considers protective of human health.
3. AIR
The risks associated with the air emissions generated
through the air stripping and vapor extraction sy~tems have been
evaluated. U~iny a unit risk factor of 1.5 X 10- cubic meters
per microgram for carbon tetrachloride, the acceptable ambient
air concentration in micrograms per cubic meter for an individual
lifetime cancer risk of 1 X 10-6 can be calculated using the
equation below:
Acceptable Ambient
Air Concentration
= (Individual Risk)/(Unit Risk Factor)
For a 1 X 10-6 individual lifetime cancer risk, the
acceptable ambient air concentration value for carbon
tetrachloride is 0.066 micrograms per cubic meter. For a
1 X 10- individual lifetime cancer risk, the acceptable
ambient air concentration value for carbon tetrachloride is
6.6 micrograms per cubic meter.
Ambient air monitoring was conducted shortly after the air
stripping and vapor extraction system went into operation (Spring
and Summer ot 1988). The results of this sampling indicated that
at two stations, the 6.6 microgram per cubic meter concentration
was exceeded based on a 9S percent confidence level over the six
sampling events in t~e survey. All of the concentrations that
exceeded the 1 X 10- cancer risk were taken during the first
sampling event when the emissions for the systems were at their
highest levels. The air monitoring survey also indicated that
additional air monitoring will not be necessary since the emis-
sions from the system will decrease over time. .Calculations
based on contaminant Qoncentrations in the soil gas and ground
water extracted from the site show that air emissions rates for
the response systems have decreased significantly over time. The
10
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results of these calculations can be found in the quarterly
reports from the Commodity Credit Corporation under total air
emissions for the systems.
SECTION IX.
DESCRIPTION OF THE ALTERNATIVES
The Expedited Response Actions were taken at the Site to
prevent the further spread of contamination to the wells that the
City of Waverly currently uses for its drinking water and to
remove contamination from the soil and ground water until a final
remedial action could be initiated. The analysis and supporting
data for the selection of the response action systems at the Site
are documented in the Engineering Evaluation Cost Analysis Report
(May 1986). It is a requirement of the Expedited Response proc-
ess that the interim remedy be compatible with the final remedial
action for the Site.
Three alternatives for final remedial action were evaluated
in the Feasibility Study using the nine criteria as outlined in
the National Contingency Plan of: technical and administrative
feasibility, capital costs, operation and maintenance costs,
environmental impacts, protection of pUblic health and the
environment, compliance with applicable or relevant and
appropriate Federal and State regulations and statutes, and
community and State acceptance.
Alternative 1.
No Further Action
Under this alternative, no further remedial actions would be
required at the site. The No Further Action alternative serves
as a basis of comparison for the other remedial alternatives.
This alternative is evaluated to determine the risks that would
be posed to public health and the environment if no action were
taken to treat or contain the contamination at the site.
This alternative would result in the shutdown of the ground
water extraction and air stripping system, and the soil vapor
extraction system and no further investigation of the Site. A
recommendation would be made to the City and or State to monitor
the water system to help prevent the consumption of contaminated
water when concentrations of VOCs exceed action levels.
Applicable or relevant and appropriate requirements would not be
met and risks to the public would increase.
continue Use of Present Systems and Install
Additional Ground Water Extraction Well
with Treatment and Discharge of Extracted Water
Under this alternative, an additional ground water
extraction well (GWEX) would be developed to supplement the
existing ground water extraction wells. The purpose of the
increased extraction rate or extraction location would be to
Alternative 2.
11
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capture ground water contaminated above the action levels
(Tables 1 and 2) set for the Site which is outside the influence
of the existing extraction well. Such a system could also reduce
the time required to clean up the aquifer system thus potentially
providing significant cost savings. Contaminated ground water
extracted from the new extraction point would require treatment
and discharge systems that meet the current criteria (Tables 1
and 2) set for the Site.
This alternative could be accomplished using an existing
well, e.g., Public Water Supply Well Number 3, as an extraction
point or siting of a new extraction well. The current air strip-
ping system has unused treatment capacity which could handle the
additional extracted water stream, or an additional treatment
system may need to be designed. The capacity of the current
discharge path would need to be examined and additional capacity
provided if necessary. It is possible that air monitoring would
be required to determine if any increase in air emissions
released by the system presents any additional health risk to
residents or workers in the area of the site. However, before
the need for a new extraction well could be evaluated, it would
be necessary to determine the full extent of contamination at the
Site and the effectiveness of the current extraction system.
Alternative 3.
Continue Operation of the Expedited Response
Action Systems and Verify the Effectiveness
of the Systems
Under this alternative, the current expedited response
action systems would continue to be operated, maintained and
monitored. In addition, the necessary investigations would be
performed to determine the extent of Site contamination and the
effectiveness of the current systems to remediate the di~covered
contamination.
1.
The investigative steps would be as follows:
Monitoring well clusters (nested wells) are required to the
north and northwest to delineate the magnitude and extent of
contamination along this potential migration route. A survey
of existing wells north, northeast, and northwest of the Site
(downgradient) should be performed. Data should be obtained
from the identified wells and used in siting the new
monitoring well clusters. The new and existing wells should
be sampled for VOCs, and a phased approach to the installa-
tion of the monitoring wells is warranted.
2.
A pumping and recovery aquifer test should be conducted,
utilizing the existing ground water extraction well and
monitoring wells to evaluate the hydraulic properties of the
aquifer. The extraction well should be pumped at a constant
rate for a minimum of 72 hours followed by a 72-hour recovery
12
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test. Results of this test would allow an evaluation of the
performance of the ground water extraction well and determine
the radius of influence or capture zone resulting from
pumping at a constant rate. Additionally, the hydraulic
parameters obtained from the aquifer test will allow for
analytical and/or numerical modeling of aquifer flow and
contaminant transport to predict migration and cleanup of the
contaminant plume.
3.
The well construction details of Public Water Supply Well
Number 3 (PWS Number 3) should be documented or determined by
geophysical logging. This will more fully explain the
presence of contamination in this ~ell and the occurrence of
clay layers within the aquifer system and whether the upper
and lower parts of the shallow aquifer are connected. This
information can be used to determine if PWS Number 3 could be
used as an additional ground water extraction well if neces-
sary. If PWS 3 is not a good candidate for an additional
extraction well or if the investigation demonstrates that
additional extraction wells are not necessary, Public Water
Supply Well (PWS) Number 3 may require plugging to prevent
cross contamination of the aquifers. If PWS Number 3 does
not provide a route for cross contamination of the upper and
lower parts of the aquifer system, it: can be returned to
service after the cleanup is complete.
4.
Sampling of the existing and new monitoring wells, PWS wells,
domestic wells, vapo~ extractioll wells, soil gas monitoring
wells, air compliance points, and the Ground Water Extraction
Well (GWEX) should continue as specified in the Performance
criteria in Tables 1 and 2.
5.
Develop a ground water flow and transport model of sufficient
detail to determine the correct pumping rate for the existing
GWEX to enable it to capture the entire plume of contamina-
tion above action levels or to determine the location and
pumping rate of additional extraction well(s) necessary to
capture the entire plume of contamination above action levels
(Tables land 2).
6.
Investigate potential uses for the treated water discharged
from the ground water extraction and air stripping system.
SECTION X.
SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
Alternatives were developed to respond to the ground water
contamination at the site. The alternatives described in the
preceding section were evaluated using criteria related to
factors mandated in Section 121 of CERCLA/SARA. Nine criteria
were developed by EPA.and are considered three major steps in the
analysis of alternatives. The first step is to ensure that
alternatives satisfy the threshold criteria. The two threshold
13
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criteria are overall protection of public health and the environ-
ment and compliance with applicable or relevant and appropriate
requirements (ARARs). Alternatives that do not satisfy these
criteria should not be evaluated further. The second step is to
compare protective and ARAR compliant alternatives against a set
of balancing criteria. The five balancing criteria are long-term
effectiveness and permanence, reduction in toxicity, mobility, or
volume achieved through treatment, implementability, short-term
effectiveness, and cost. The third and final step is to evaluate
the alternatives on the basis of modifying criteria. The two
modifying criteria are State and community acceptance.
1.
Threshold criteria
a.
Protection of Human Health and the Environment
Alternatives 2 and 3 would both be protective of human
health and the environment. They both reduce the risk of
exposure to contaminated drinking water by containing the spread
of the plume of contamination to the operating City wells, and
they both reduce the toxicity and volume of contaminated ground
water by removing contaminants from the ground water. The risks
associated with the air emissions from the system have been
evaluated using ambient air monitoring data. The results of the
monitoring showed that as long as the air emission rate from the
system does not exceed the performance criteria levels (Tables 1
and 2) no health concerns would be associated with the emissions.
Risks associated with site soils are low and the site is fenced
to prevent access.
Ambient air monitoring was done at the initial startup of
the currently operating air stripping and vapor extraction sys-
tem. This monitoring and mOdeling work, based on the data taken,
. indicated that the air emissions from the systems did not need
further monitoring to protect human health. The current
(March 1990) air emission rate is 0.0011 grams per second, which
is less than 1/4 pound per day and less than 100 pounds per year
which is less than the limit set by the State of Nebraska's Air
Pollution Control Rules and Regulations emission rates of
100 pounds per day and 2.5 tons per year, respectively.
b.
Compliance with ARARs
Alternatives 2 and 3 will meet the ARARs by reducing ground
water contamination to meet state and Federal standards for
drinking water and existing state and Federal air regulations.
Alternatives 2 and 3 will also treat the extracted ground water
so that it will meet The National Pollutant Discharge Elimination
System's (NPDES's) discharge limits set for the site.
14
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2.
Balancing criteria
Alternatives 2 and 3 provide for the permanent removal of
contaminants from the Site and containment of the plume of
contamination. Both alternatives include ground water pump and
treat and soil vapor extraction systems which are proven
technologies and will achieve a reduction in mobility, toxicity
and volume of contaminants in the soil and ground water at the
Site. Alternative 3 (continued operation of the current response
action systems) will require approximately 15 years to restore
the aquifer to its beneficial use as a drinking water source.
Alternative 2 (install an additional ground water extraction
well) has the potential to shorten the time required for cleanup,
and it is estimated that the time would be shortened to 10 years.
However, additional data regarding the exact boundaries of the
plume and the zone of influence of the existing ground water
extraction well is required before any time saving provided by an
additional well or the cleanup time for the existing well can be
estimated accurately.
Alternatives 2 and 3 will require construction activities on
or near the Site. Both alternatives will require monitoring well
construction, and Alternative 2 may also require the construction
of an extraction well. Contaminated materials may be encountered
during well construction, but any release of volatile compounds
will rapidly disperse and is not likely to pose a public health
risk. Onsite workers may need protective equipment.
The ground water extraction and air stripping system, and
vapor extraction system for Alternative 3 are already operating
onsite, so the only capital cost would be for investigation and
installation of monitoring wells. The operation and maintenance
costs for Alternative 3 are approximately $451,000 per year at
present. Alternative 2 would require the installation of an
additional ground water extraction well which would have an
approximate capital cost of $47,000 depending on size and
location and would require adding $13,000 to the approximate
yearly operation and maintenance costs for Alternative 3.
The cost comparison for the alternatives would be as follows:
Alternative 2 (Additional Extraction Well)
TOTAL CAPITAL COSTS.....................$
167,000
TOTAL 0&" COSTS PER YEAR................$
464,000
PRESENT WORTH (10 years, 10 percent)...$ 3,038,000
15
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Alternative 3 (Continue operating CUrrent Systems)
TOTAL CAPITAL COSTS.....................$
TOTAL O&M COSTS PER YEAR................$
120,000
451,000
PRESENT WORTH (15 years, 10 percent)...$ 3,550,000
Alternatives 2 and 3 have very similar costs and both are
designed to be protective of health and the environment. Further
investigation is required in order to determine the need for the
additional extraction well in Alternative 2 and to estimate the
time reduction it may provide.
3.
Modifying Criteria
a. state Acceptance
The Nebraska Department of Environmental Control supported
the Environmental Protection Agency's selection of the preferred
alternative, Alternative 3, as presented in the Proposed Plan
during the public meeting in Waverly on August 20, 1990.
b. community Acceptance
The reservations, concerns, and supporting or opposing
comments of the community on the Feasibility Study, the Proposed
Plan, and other information in the Administrative Record were
made known to the Environmental Protection Agency during the
thirty-day public comment period and during the public meeting
held on August 20, 1990. The pUblic's comments are addressed in
the Responsiveness Summary.
SECTION XI.
THE SELECTED REMEDY
Based on available data and analysis conducted to date, the
Environmental Protection Agency has selected the continued opera-
tion of the current expedited response action systems and the
performance of the necessary investigations to verify their
effectiveness (Alternative 3) as the remedy for the Waverly
Ground Water Contamination Site. This alternative provides
protection to human health and the environment trom the threats
associated with the Site and limits the migration of contaminants
in and to the aquifer at the Site. This alternative also pro-
vides for compliance with applicable or relevant and appropriate
laws and regulations. .
The purpose of this response action is to prevent potential
exposure to contaminated ground water, protect uncontaminated
ground water for future use by preventing further migration of
the contaminated ground water plume, and restore contaminated
ground water for future use as a source of drinking water by
16
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reducing the Site contaminants to their respective performance
criteria levels (Tables 1 and 2). At the completion of the
remediation, the level of Site contamination remaining in the
ground water at or below the Applicable or Relevant and
Appropriate Requirement levels will correspogd to an excess
lifetime cancer risk within the range of 10- to 10-4
through the exposure routes of direct contact and ingestion. For
example, carbon tetrachloride in ground water in excess of five
micrpgrams per liter will be remediated.
The installation of an additional ground water extraction
well (Alternative 2) is not warranted at this time. The investi-
gation necessary to design and site this additional well would be
very similar to the investigation needed for Alternative 3.
Based on the current Site data, the current systems are making
progress toward Site cleanup.
The Environmental Protection Agency retains the authority to
reassess the need for additional response actions at this Site as
appropriate upon receipt of new information warranting a change.
SECTION XII.
THE STATUTORY DETERMINATIONS
The Environmental Protection Agency's primary responsibility
at Superfund sites is to undertake remedial actions that achieve
adequate protection of human health and the environment. In
addition, Section 121 of CERCLA establishes several other statu-
tory requirements and preferences. These specify that when
complete, the selected remedial action for this site must comply
with applicable or relevant and appropriate environmental laws
unless a statutory waiver is justified. The selected remedy also
must be cost effective and utilize permanent solutions and alter-
native treatment technologies or resource recovery technologies
to the maximum extent practicable. Finally, the statute includes
a preference for remedies that employ treatment that permanently
and significantly reduce the volume, toxicity, or mobility of
hazardous wastes as their principal element. The following
sections discuss how the selected remedy meets these statutory
requirements.
1.
Protection of Human Health and the Environment.
The selected remedy protects human health and the environ-
ment through extraction and treatment of contaminated ground
water and soil vapor. The contaminants will be permanently
removed from the ground water by air stripping and from the soil
through volatilization by active soil vapor extraction. The
volatile gases will be transferred to the air stream for release
to the atmosphere.
17
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Extraction of the contaminated ground water will also elimi-
nate the threat of exposure due to the spread of contamination to
a larger area by checking the migration of the plume. Volatili-
zation of contaminants from Site soils will eliminate the source
of continued contamination of the ground water thus reducing the
time needed for remediation. Risks associated with the ingestion
of contam~nated ground water from the Site are as high as
1.2 X 10-. The selected remedy, by extracting and treating
the contaminated ground water, will reduce the risk below unac-
ceptable levels. Ambient air monitoring and modeling have also
been done on the stack emissions from the response action sys-
tems. This monitoring has shown that the systems, when operating
within performance criteria (Tables 1 and 2), do not pose an
unacceptable risk to the community. The combined emission rates
from the response action systems have been well below the 0.147
grams per second performance limit since daily operations began
in February 1988. There are no short-term threats associated
with the selected remedy that cannot be readily controlled. In
addition, no adverse cross-media impacts are expected from the
remedy.
Compliance with Applicable or Relevant and Appropriate
Requirements.
The selected remedy of ground water extraction and air
stripping, and soil vapor extraction is designed to meet all
applicable or relevant and appropriate requirements of Federal
and more stringent State environmental laws. The requirements
applicable to the Waverly site are outlined in Section VII. The
ground water extraction and air stripping system, and the soil
vapor extraction system will continue to operate until the
aquifer and the soil gas meet their respective remediation goals
of 5 micrograms per liter and 6.5 micrograms per cubic meter as
specified in the performance criteria for each system in Tables 1
and 2. The remedial action systems are designed so that air
emissions and surface water discharge will meet their respective
State and Federal discharge limits.
2.
3.
Cost-Effectiveness.
The selected remedy is cost-effective. It provides a high
degree of protection to the current water supply wells in
Waverly, and no capital expenditures are required for its
implementation. The systems have already operated effectively
for over two years and have removed contaminants from the soil
and ground water at the Site. Ground water extraction and air
stripping, and soil vapor extraction were chosen for
implementation at the time of the expedited response action over
a range of other technologies because of their implementability
and cost effectiveness.
18
~
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4.
utilization of Permanent Solutions and Alternative Treatment
Technologies or Resource Recovery Technologies to the Maximum
Extent Practicable.
The Environmental Protection Agency has determined that the
selected remedy represents the maximum extent to which permanent
solutions and treatment technologies can be utilized in a cost-
effective manner for the Waverly Ground Water Contamination Site.
Of those alternatives that are protective of human health and the
environment and comply with applicable standards, the Environ-
mental Protection Agency has determined that this selected remedy
provides the best balance of tradeoffs in terms of long-term
effectiveness and permanence, reduction in toxicity, mobility, or
volume achieved through treatment, short-term effectiveness,
implementability, cost, also considering the statutory preference
for treatment as a principal element and considering State and
community input.
The selected remedy addresses the principal threat at the
site by reducing the toxicity, mobility, and volume of the
contaminants in the ground water: complies with applicable or
relevant and appropriate requirements: provides short-term
effectiveness: and protects human health and the environment.
The remedy is already in place and no additional capital costs
are necessary for its implementation. The selected remedy is
effective and already in place and is therefore determined to be
the most appropriate solution for the contaminated ground waters
at the Waverly Ground Water Contamination Site.
The State of Nebraska concurs with the selected remedy.
Public comments were received concerning the potential use for
the treated water from the system. Those comment are fully
addressed in the Responsiveness Summary.
The Proposed Plan for the Waverly Site identified
Alternative 3 as the preferred alternative for site remediation.
After a review of all written and verbal comments submitted
during the pUblic comment period, the Environmental Protection
. Agency has determined that no significant changes to the remedy,
as it was originally identified in the Proposed Plan, were
necessary.
5.
Preference for Treatment as a Principal element
The selected remedy uses air stripping technology for ground
water treatment and active soil vapor extraction for source
control and thus satisfies the statutory preference for remedies
that employ treatment of the principal threat which permanently
and significantly reduces the toxicity, mobility, or volume of
hazardous substances as a principal element.
19
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XIII.
I
DOCUMENTATION OF SIGNIFICANT DIFFERENCES
No siqnificant changes were made to the recommended
alternative in the Proposed Plan.
20
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RECORD OF DECISION
RESPONSIVENESS SUMMARY
WAVERLY GROUND WATER CONTAMINATION SITE
WAVERLY, NEBRASKA
Prepared By:
THE ENVIRONMENTAL PROTECTION AGENCY
REGION VII
KANSAS CITY, KANSAS
September 1990
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WAVERLY GROUND WATER CONTAMINATION SITE
RESPONSIVENESS SUMMARY
A.
OVERVIEW
In the Proposed Plan released to the public, the
Environmental Protection Agency presented a preferred alternative
for the cleanup of the Site. The recommended alternative was to
continue the operation of the current response action systems
which address the remediation of contaminated ground water and
contaminated soil. The preferred alternative involved the
extraction and air stripping of contaminated ground water to
remove contaminants from the aquifer and contain the spread of
the contaminant plume, and the extraction of soil vapor to
control the source of contamination.
Based on the comments received during the public comment.
period, there is general support for the preferred alternative.
The major comments received addressed the need to find alternate
uses for the treated water currently discharged from the system
to a nearby creek and the effect of the ground water extraction
well on the availability of water in the Waverly aquifer for
agricultural uses. Other comments received related to the
operation, cost, and effectiveness of the treatment systems.
B.
BACKGROUND ON COMMUNITY INVOLVEMENT
Community interest in the site dates back to 1982 when
contamin~tion of the public water supply wells in Waverly was
first discovered. The major issues expressed at that time were
concerned with providing the community with a safe drinking water
supply. The community was also involved during the summer of
1987 when the decision was made to install the current response
action systems at the Site. A public meeting was held in
August 1987 with the Mayor and City Council to present the
planned response actions and to solicit comments on the plan. A
door-to-door survey of the residences near the Site was conducted
to solicit public concerns associated with the response actions
planned.
The public comment period on the preferred. alternative as
outlined in the Proposed Plan began on August 9, 1990 and ended
September 7, 1990. A public meeting was held in Waverly on
August 20, 1990. The responsiveness summary addresses comments
received during this period.
C.
SUMMARY OF COMMENTS RECEIVED DURING THE PUBLIC COMMENT PERIOD
Comments received during the public comment period on the
Feasibility Study and Proposed Plan for the Waverly Ground Water
contamination Site are briefly summarized below. The comments
are categorized by topics.
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Remedial Alternative Preferences
1.
EPA's preferred plan is to continue the operation of the
present ground water pump and treat and soil vapor extraction
systems with additional inv.estigation to evaluate the
effectiveness of the method. The process could take as long
as 30 years. The commentor's questions were in the following
three general areas:
a)
Are there other possible ways to remove the
contaminants?
b)
If so, how seriously have these alternatives been
considered?
c)
What are the reasons that other alternatives were
not seriously considered?
EPA ReSDonse
It is difficult to estimate the exact duration of a ground
water cleanup such as the one taking place at Waverly. Based
on the average yearly decline in the concentration of carbon
tetrachloride in the ground water extracted from the Waverly
aquifer, an estimate nf 1~ years to achieve the action level
concentration of 5 parts per billion in the extracted water
could be made. The thirty year duration for the cleanup of
the site suggested in this comment is not an EPA estimate.
The Engineering Evaluation Cost Analysis (EEjCA) for the
Expedited Response Action at the Waverly Ground Water Contam-
ination site completed May 16, 1986 (Revised March 27, 1987)
compared several alternatives to protect public health and
the environment from site related hazards. The alternatives
considered for insitu soil treatment were active soil gas
extraction, biological treatment, chemical treatment, and
photolysis. The alternatives considered for ground water
treatment were pump and discharge, air stripping, activated
carbon treatment, and biological treatment. Excavation of
. Site soils and offsite disposal, and Site encapsulation were
also considered as alternatives. Based on the criteria of
technical reliability, feasibility, and applicability; pro-
tection of public health, safety, and the environment; and
cost effectiveness; the combination of soil vapor extraction
for source control and air stripping and surface discharge
for ground water treatment and plume control were selected as
the best options for the Waverly Site.
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2.
Alternative 2 is the installation of an additional extraction
well at the Site. Why not move to install the additional
well now and accelerate the cleanup process?
£.fA ReSDonse
The performance monitoring carried out during the more than
two years of operation of the current systems has shown that
the contaminant plume is being drawn back. Additional ground
water monitoring points are needed to verify the effec-
tiveness demonstrated by the systems in all directions.
Additional data will also be needed to determine the effec-
tiveness of an additional extraction well. Once the effec-
tiveness of the current systems has been fully evaluated, the
need for additional ground water extraction capacity can be
determined.
Technical Questions/Concerns Regarding Remedial Alternatives
1.
What has been done and what can be done to use the treated
water discharged for the systems at Waverly?
~ ReSDonse
2.
The current ground water extraction well withdraws about
100 gallons of water per minute for the shallow portion of
the waverly aquifer. The only possible use for the discharge
water evaluated at the time the current systems were
installed was to carbon polish the water and provide it to
the City water supply. The option chosen was surface dis-
charge to a nearby creek. Potential alternatives for the
reuse or recycling of the treated water from the system will
be investigated as part of the further investigation of the
effectiveness of the systems.
Concern was expressed as to the depletion of the ground water
aquifer in the Waverly area by the continued "pump, treat,
and discharge process" for an extended, indefinite period. A
question was raised as to whether EPA has conducted an impact
analysis of this continuous pumping on the local aquifer.
Similar concern was expressed as to the impact of pumping
Waverly's Public Water Supply Well Numbers 6 and 7 located
southwest of Waverly on the availability of water for
agricultural and other uses.
.EfA ReSDonse
The ground water extraction well withdraws only about
100 gallons per minute from the aquifer. During the design
of the pump and treat system, data from the State of Nebraska
Conservation and Survey Division observation well, approxi-
mately one mile west of Waverly, indicated that the aquifer
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was underutilized having risen over five feet since 1970.
Further investigation into the impact of continued pumping of
the ground water extraction well on the availability of
ground water for agricultural and other uses will be
addressed.
J.
The location or impact of the City of Waverly's wells on the
stability of the water supply in the region has not been
evaluated as part of the remedial action.
Are private water supplies being adversely affected by the
contamination at the site? What steps are being taken to
compensate people if their wells are contaminated? Are
measures being taken to remove contamination from their water
supply?
EPA ReSDonse
4.
Samples taken from one private drinking water well in the
area of the Site have shown concentrations of Site related
contaminants above acceptable levels. This household is
being provided bottled water for consumption. The extension
of the public water system to include this residence was
investigated, but an agreement with the City of Waverly on
the terms and scope of the water main extension could not be
reached. The installation of a carbon filtration system was
also investigated but the well and distribution system for
the home could not support the system. The installation of a
new household well in now under investigation.
One residential well located north of the Site has continued
to show contamination during the more than two years of
operation of the remedial action systems. What assurances do
we have that a portion of the plume has not been released and
will no~ continue to spread contamination toward Salt Creek?
What can be done if the plume is not being captured by the
current systems?
E.EA ReSDonse
. The additional investigation proposed as part of the con-
tinued response action will address these concerns. The
residential well referred to in the question is a hand dug
well in the basement of the residence. The reliability of
the well as a monitoring point is questionable. The investi-
gation of the effectiveness of the remedy will include the
development of monitoring wells in the areas where questions
remain as to whether the entire plume has been captured.
Should data indicate that the current remedial action systems
are not progressing toward cleanup of the Site, additional
remedial action may be required.
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5.
How is the treatment of contaminated 80il at the site being
addressed?
EPA ReSDonse
The soil contamination at the Site does not present an
unacceptable risk to human health and, therefore, does not
require remediation. However, the contaminants in the soil
provide a source of contamination for the ground water at the
site. The soil vapor extraction system was designed to
remove this source of contamination, and no further remedial
action is planned for the site soils once the action levels
have been reached in the soil gas.
6.
Is the cleanup rate at the Waverly site satisfactory?
does it compare to other ground water cleanups?
How
EPA ResDonse
The remedial action systems at Waverly have made good
progress toward the eventual cleanup of the Site. The con-
centration of contaminants in the ground water extracted from
the aquifer has declined from a concentration near 3,000
parts per billion carbon tetrachloride to a concentration
near 200 parts per billion in the two years since the systems
went into operation.
It is difficult to compare cleanup actions at different sites
due to the vast difference in site conditions that usually
exist. The Waverly systems would compare favorably with most
other similar cleanup actions.
Public participation Process
1.
One individual at the public meeting on August 20, 1990
requested that another public meeting be held since all of
his statements had not gotten into the record.
EPA ResDonse
This individual statements were recorded during the public
meeting on August 20, 1990 and this individual was asked to
provide further comments in writing. EPA received written
comments from this individual on September 11, 1990.
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Cost/Funding Issues
1.
What is the total cost of the project?
EPA Response
The cost estimate for the continued operation of the remedial
action systems for a 15 year period was estimated at
$3,550,000. The cost to date for the entire project is
approximately $4,000,000. The total estimated cost of the
project would thus be approximately $7,550,000.
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