PB96-964508
EPA/ROD/R09-96/150
December 1996
EPA Superfund
Record of Decision:
Fresno Municipal Sanitary Landfill,
Fresno, CA
9/30/1996
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Record of Decision
Fresno Sanitary Landfill
Fresno, California
September 30, 1996
U.S. Environmental Protection Agency
Region IX, San Francisco
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TABLE OF CONTENTS
RECORD OF DECISION
PART I - DECLARATION
1.0 Statement of Basis and Purpose 1
2.0 Assessment of the Site 1
3.0 Description of the Remedy 1
4.0 Statutory Determinations 2
PART II - DECISION SUMMARY
1.0 Site Name, Location, and Description 3
2.0 Site History and Enforcement 3
3.0 Highlights of Community Participation 6
4.0 Scope and Role of Operable Unit 6
5.0 Summary of Site Characteristics 7
6.0 Summary of Site Risks 11
7.0 Applicable or Relevant and Appropriate Requirements 13
8.0 Description of Alternatives 16
8.1 Common Elements 16
8.2 Alternative 1 - Limited Action 18
8.3 Alternative 2 - Landfill Perimeter Plume Containment and Off-site
Plume Monitoring 19
8.4 Alternative 3 - Landfill Perimeter Plume Containment and Off-site
Plume Containment 20
8.5 Alternative 4 - Landfill Perimeter Plume Containment and Off-site
Plume Restoration 22
8.6 Phased Implementation of the Remedial Action 23
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9.0 Summary of Comparative Analysis 26
9.1 Overall Protection of Human Health and the Environment 26
9.2 Compliance with 26
9.3 Long-Term Effectiveness and Permanence 26
9.4 Short-Term Effectiveness 27
9.5 Reduction of Toxicity, Mobility, and Volume Through Treatment 27
9.6 Implementability 28
9.7 Cost 29
9.8 State Acceptance 30
9.9 Community Acceptance 30
10.0 The Selected Remedy 30
11.0 Statutory Determinations 32
11.1 Protection of Human Health and the Environment 32
11.2 Applicable or Relevant and Appropriate Requirements (ARARs) .... 32
11.3 Cost-Effectiveness 32
11.4 Utilization of Permanent Solutions and Alternative Treatment
Technologies to the Maximum Extent Practicable 32
12.0 Documentation of Significant Changes 33
PART III - Responsiveness Summary
1.0 Summary of Major Comments 34
2.0 Comprehensive Response to All Comments 34
List of Figures
Figure 1 Site Features Map
Figure 2 General 3-D Cross Section
Figure 3 Groundwater Well Locations
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RECORD OF DECISION
Fresno Sanitary Landfill Superfund Site
Fresno, California
EPA ID # CAD980636914
PART I - DECLARATION
1.0 Statement of Basis and Purpose
This Record of Decision (ROD) presents the selected final remedial action for
the Fresno Sanitary Landfill Superfund site (the Site) in Fresno California. This
document was 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 U.S.C. § § 9601
et seq. and, to the extent practicable, in accordance with the National Oil and
Hazardous Substances Pollution Contingency Plan (NCP).
This decision is based on the Administrative Record for the site.
The State of California Department of Toxic Substances Control, as the lead
state agency, concurs with this remedy.
2.0 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.
3.0 Description of the Remedy
This operable unit is the final action of two operable units for the site. The first
operable unit at the site involved a landfill cover, a landfill gas collection and
treatment system, and storm water runoff collection system. This action addresses
the groundwater. The selected remedy includes:
a groundwater monitoring system,
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a landfill perimeter groundwater containment system,
a plume perimeter containment system, and
a aquifer restoration system
4.0 Statutory Determinations
The selected remedy is protective of human health and the environment, and
complies with the Federal and State requirements that are legally applicable or
relevant and appropriate to the remedial action, and is cost-effective. This remedy
uses 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. Because
this remedy will result in hazardous substances remaining on-site above health-based
levels, the five year review will apply to this action.
Keith Takata Date
Director, Superfund Division, EPA Region IX
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RECORD OF DECISION
Fresno Sanitary Landfill Superfund Site
Fresno, California
EPA ID#CAD980636914
PART II - DECISION SUMMARY
1.0 Site Name. Location, and Description
The Fresno Sanitary Landfill is located four miles southwest of the City of
Fresno in Fresno County, California. The landfill consists of approximately 145 acres
and is bounded on the north by Jensen Avenue, on the east by West Avenue, on the
south by North Avenue and west by agricultural fields. The landfill stands
approximately 60 feet above the surrounding flat grade and extends approximately 30
feet below the surrounding grade. The landfill is fenced. The groundwater
underneath the site is part of a sole-source aquifer used as drinking water and
irrigation water for the residents of Fresno. Eight water supply wells and many
domestic wells are within 3 miles of the site.
2.0 Site History and Enforcement
The Fresno Sanitary Landfill was owned and operated solely by the City of
Fresno from 1935 to 1987, and is reported to be the oldest compartmentalized landfill
in the Western United States. Operations began in the north section in 1935 as short
trenches were dug to a depth of three feet and eventually increased to 25 feet. Waste
was then dumped into the trench by collection trucks and the pile was leveled off and
compacted. A second trench was dug adjacent to the first trench, and the dirt from
the second trench was used to cover the waste fill. The landfill was never lined.
The Fresno Sanitary Landfill was first evaluated by EPA pursuant to a CERCLA
Section 103(c) notification to the City of Fresno Solid Waste Management Division
filed on May 27, 1981. The California Department of Toxic Substances Control
(DTSC) (formerly, California Department of Health Services) conducted a preliminary
inspection of the site in 1984 in response to complaint letters from nearby residents.
The state inspectors found off-site migration of methane and also reviewed the
documentation of volatile organic compound (VOC) contamination of the groundwater.
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The Fresno Sanitary Landfill site was added to the National Priorities List on
October 1989. EPA sent a General Notice letter of liability in April 1990. On June 22,
1990 EPA sent the City a Special Notice letter asking the City to submit a good faith
offer to conduct the remedial investigation and feasibility study for the Fresno Sanitary
Landfill. On September 21, 1990, EPA and the City signed an Administrative Order
on Consent (EPA Docket 90-22) wherein the City agreed to conduct the remedial
investigation and feasibility study.
In 1988, the City of Fresno installed two methane barriers on the north and
south side of the landfill to prevent the exposure of the nearby residents to migrating
landfill gases. In 1990, EPA held discussions with the City of Fresno regarding the
continuing landfill gas migration away from the landfill. Subsequently, with the
consent of the City, EPA issued a Unilateral Order (US EPA Docket No. 90-19) to
install a vacuum system on the barriers and to install a landfill gas extraction system
in the landfill. After the Order, it was determined that a landfill gas extraction system
would need to be designed in conjunction with the landfill cover. EPA then directed
the City to implement a landfill gas monitoring program to ensure that residents near
the landfill were not being exposed to vinyl chloride (a potent carcinogen in the
migrating landfill gas) in their homes. The City tested the in-home air of seven
potentially affected residences. No vinyl chloride was detected in any of the homes on
three different occasions (November 1991, March 1992 and November 1992). The
monitoring system showed high levels of vinyl chloride up to 700 feet away from the
landfill in the soil gas.
From September 1990 to August 1991, the City installed the vacuum system on
the existing methane barriers. During the operation of these systems, it was
discovered that the existing methane barriers were not designed for a vacuum
extraction system. EPA determined that the operation of the vacuum system would be
inappropriate because it did not stop the landfill gases from migrating past the
barriers.
Concurrent to the landfill gas work, the City began its investigation of the
landfill trash prism and the groundwater plume migrating from the site. During the soil
gas investigation, the City requested that the investigation for the landfill trash prism
and the landfill gas be separated from the groundwater investigation in order to speed
the decision for that unit. Thus the investigation at the site was divided into two
operable units: the source control operable unit which addressed the landfill trash
prism; and the groundwater operable unit which addressed the groundwater impacted
by the landfill contaminants. The feasibility study for the source control operable unit
was completed in September 1992. In March 1993, EPA released a proposed plan for
the source control operable unit which included a landfill cover consisting of a
geomembrane material, a soil foundation layer and a soil cover layer; a landfill gas
extraction and destruction system and a storm water run-off collection system. The
Record of Decision for this proposed plan was signed in September 1993.
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The Administrative Order on Consent between the City and EPA was amended
on December 17, 1993 (EPA Docket 94-07) to include the design of the landfill cap
and other components of the system. The design is nearly 90% complete and is
scheduled to be finished in February 1997.
Concurrent to the landfill source control operable unit remedial investigation and
feasibility study work, the City initiated the remedial investigation and feasibility study
for the groundwater operable unit. The Remedial Investigation for the groundwater
operable unit was completed in May 1994. The Risk Assessment was completed in
September 1994. The Feasibility Study was completed in July 1996.
3.0 Highlights of Community Participation
The Remedial Investigation Report, the Feasibility Study and the Proposed Plan
for the groundwater operable unit at the Fresno Sanitary Landfill Superfund site were
released to the public in July 1996. These three documents were made available to
the public in both the Administrative Record and the EPA Records Center in Region IX
and at the Fresno County Library in Fresno, California. The notice of the availability of
the Administrative Record was published in the Fresno Bee on July 22, 1996. A
public comment period was held from July 24, 1996 through August 23, 1996. In
addition, a public meeting was held on August 1, 1996. At this meeting,
representatives from EPA and the State of California answered questions about the
site and the remedial alternatives under consideration. A response to the comments
received during this period is included in the Responsiveness Summary, which is part
of this Record of Decision. This decision document presents the selected remedial
action for the groundwater operable at the Fresno Sanitary Landfill Superfund Site, in
Fresno, California, chosen in accordance with CERCLA, as amended by SARA, and,
to the extent practicable, the National Contingency Plan. The decision for this site is
based on the documents in the Administrative Record.
4.0 Scope and Role of Operable Unit
As with many Superfund sites, the problems at the Fresno Sanitary Landfill are
complex and varied. As a result, EPA organized the work into two operable units.
These are:
Operable Unit 1: Source Control Operable Unit
Addresses the trash prism and landfill gas
Operable Unit 2: Groundwater Operable Unit
Addresses the groundwater contamination
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EPA has selected a remedy for the first operable unit. The remedy is in the
design phase and construction is planned for late spring 1997. This second and final
operable unit addresses the threat of groundwater contamination in the sole source
aquifer surrounding the facility.
5.0 Summary of Site Characteristics
A remedial investigation (Rl) was conducted at the Fresno Sanitary Landfill by
the City of Fresno as required by the Administrative Consent Order. Hydrogeologic
investigation activities included the review of regional and previous site investigation
reports, collection of water level measurements, performance of aquifer hydraulic
tests, and evaluation of nearby irrigation-related recharge and pumping. These
investigations indicated that regional groundwater flow near the Fresno Sanitary
Landfill is to the southwest. Factors affecting regional flow directions include a
drawdown cone within the City of Fresno due to municipal groundwater pumping, a
recharge mound at the Fresno Regional Wastewater Facilities located several miles
west of the site, and irrigation pumping from deep wells farther to the west and south.
Regional water levels have decreased over time due to groundwater pumping that is
in excess of recharge. Local groundwater flow rates and direction are affected by
nearby agricultural pumping wells. Pumping of agricultural wells near the site induces
downward vertical gradients that are not present during non-pumping months.
Four hydrostatigraphic units were identified including (in descending order) a
shallow sandy A aquifer at the water table, a silt and clay B aquitard, a B aquifer with
interbedded silts and discontinuous sands, and a continuous sandy C aquifer at
approximately 250 feet below the site. Shallow groundwater is unconfined beneath
the site, and flow directions range from the southwest to west-northwest. Deeper
groundwater present in the B and C aquifer units is under semi-confined conditions.
All the groundwater zones are sources of drinking and/or irrigation water.
The remedial investigation included chemical analysis of groundwater from
domestic wells, monitoring wells and irrigation wells. Organic compounds detected at
the site which may pose a risk are tetrachloroethylene, trichloroethylene, vinyl chloride,
frans-1,2-dichloroethene; c/s-1,2-dichloroethene; 1,1-dichloroethane; 1,2-
dichloroethane; 1,2-dichlorobenzene; 1,4-dichlorobenzene; benzene; 1,1-
dichloroethene; 1,2-dichIoropropane; chloroform; dichlorodifluoromethane;
trichlorofluoromethane; toluene; and chlorobenzene. The highest concentrations and
the greatest lateral extent were found in the A aquifer. Detections of volatile organic
compounds in groundwater extend to approximately 1,300 feet downgradient of the
landfill. Concentrations of volatile organic compounds detected in the monitoring wells
screened in the B aquifer are at least an order of magnitude lower than the A aquifer.
No analytical detections of the contaminants of concern were found in the C aquifer.
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GENERAL 3D CROSS SECTION
J96 059 / Mc1 IFtk
FRESNO SANITARY LANDFILL
FRESNO, CALIFORNIA
FIGURE 2
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Residential domestic wells are located to the north, east, and south of the
landfill. These wells tap into the A and the B aquifers. The chemical concentrations at
these wells do not exceed their respective maximum contaminant levels (MCLs) in
drinking water, with the exception of one well located south of the site (2168N) which
exceeded the MCLs for tetrachloroethylene (5 ug/l) with one result of 8.6 ug/l in
August 1993. This well is targeted for decommissioning.
Several agricultural irrigation wells are located downgradient of the landfill.
These wells are apparently completed within the B and C aquifers. Operation of these
wells is intermittent. Irrigation well 16 (otherwise known as U16) is located on the west
central edge of the landfill. Operation of this well may be responsible for drawing
volatile organic compounds down from the A aquifer into the B aquifer, and potentially
the C aquifer. Irrigation well 16 is targeted for decommissioning. Downward vertical
hydraulic gradients are only apparent during summer months when the irrigation wells
are in operation.
The City of Fresno instituted a sampling program for the monitoring wells and
nearby domestic and irrigation wells in July 1992. The range of chemical
concentrations detected is as follows:
Chemicals of Concern in Groundwater
Tetrachloroethylene (PCE)
Trichloroethylene (TCE)
Vinyl chloride
1,1-Dichloroethane
1,2-Dichloroethane
1 ,2-Dichlorobenzene
c/s-1 ,2-Dichloroethene
frans-1 ,2-Dichloroethene
1,1-Dichloroethene
1,2-Dichloropropane
1 ,4-Dichlorobenzene
Benzene
Chlorobenzene
Chloroform
Dichlorodifluoromethane
Trichlorofluoromethane
Toluene
Range of Concentrations (7/92 - 5/95;
Not detected to 1 1 0 ug/l
Not detected to 83 ug/l
Not detected to 150 ug/l
Not detected to 26 ug/l
Not detected to 2.1 ug/l
Not detected to 4.4 ug/l
Not detected to 560 ug/l
Not detected to 19 ug/l
Not detected to 1.3 ug/l
Not detected to 1 1 ug/l
Not detected to 14 ug/l
Not detected to 6.1 ug/l
Not detected to 4.8 ug/l
Not detected to 2.7 ug/l
Not detected to 290 ug/l
Not detected to 33 ug/l
Not detected to 7.2 ug/l
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6.0 Summary of Site Risks
EPA prepared a risk assessment for potential exposure to chemicals detected
in groundwater at the Fresno Sanitary Landfill. The EPA risk assessment looked at
two potential exposure pathways: ingesting contaminated drinking water; and inhaling
chemicals during showering. Exposure to toxic compounds may occur as an
individual showers with water contaminated with volatile organic compounds.
Contaminants dissolved in the potable water supply may be released into the air
during showering and inhaled by the individual. Inhalation exposures are modeled by
estimating the rate of chemical release into the air, the buildup and the decay of
volatile organic compounds in the shower room air, and the amount of airborne volatile
organic compounds inhaled while the shower is both on and off. Based on the risk
assessment, the potential risk associated with this pathway was much less than the
drinking water exposure pathway.
The risk assessment evaluated potential human health risks under both current
conditions and reasonable future conditions. The risk assessment evaluated potential
carcinogenic and non-carcinogenic risks to off-site residential receptors. Excess
lifetime cancer risks are determined by multiplying the intake level with the cancer
potency factor. These risks are probabilities that are generally expressed in scientific
notation (e.g. 1x10'6). An excess lifetime cancer risk of 1x10~6 indicates that as a
plausible upper bound, an individual has a one in a million chance of developing
cancer as a result of site-related exposure to a carcinogen over a 70-year lifetime
under specific exposure conditions at the site.
Concern for potential noncarcinogenic effects of a single contaminant in a
single medium is expressed as the hazard quotient (HQ) (or the ratio of the estimated
intake derived from the contaminant concentration in a given medium to the
contaminant's reference dose). The reference dose is an estimate of the maximum
quantity of a contaminant to which a person can be exposed over a long period of
time and still show no adverse health effects. By adding the HQs for detected
contaminants within a medium and across media to which a given population may be
reasonably exposed, a hazard index (HI) can be generated. The HI provides a useful
reference point for gauging the potential significance of multiple contaminant
exposures within a single medium or across media.
For the current land use conditions, it was assumed that the site was in its
present physical state, and there were no workers present. Groundwater analytical
data collected during the remedial investigation from residential wells was used to
estimate potential risks to off-site residents. Under the current land use scenario, the
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average and reasonable maximum exposure (RME) cancer risk associated with
drinking water ingestion were estimated as follows:
Adult Average: 2 x 10'7 Adult RME: 1 x 1CT6
Child Average: 3 x 10'7 Child RME: 6 x 10'7
Potential noncarcinogenic risks, as expressed in terms of the hazard index,
were estimated as follows:
Adult Average: 0.05 Adult RME: 0.1
Child Average: 0.1 Child RME: 0.2
For the future land use scenario, it was assumed that the facility is inactive, the
landfill is fenced-off, and a low permeability cap is installed. This is consistent with the
1993 Record of Decision. It also assumed that the concentration levels would not
change over time, i.e. the source of leachate is not a continuing source and no dilution
would occur. Groundwater monitoring well data from the remedial investigation was
used to calculate concentrations for the groundwater ingestion pathway. Nine
chemicals of potential concern, both organic and inorganic compounds, were
evaluated in the risk analysis. These include 1,1-dichloroethane, methylene chloride,
tetrachloroethylene, trichloroethylene, trichlorofluoromethane, vinyl chloride, barium,
manganese, and selenium.
Potential excess cancer risks associated with drinking water ingestion under
future land use scenario were estimated to be as follows:
Adult Average: 1 x 10'5 Adult RME: 8 x 10'5
Child Average: 2 x 10'5 Child RME: 4 x 10'5
Potential noncarcinogenic risks, as expressed in terms of the hazard index,
were estimated to be as follows:
Adult Average: 0.2 Adult RME: 0.4
Child Average: 0.4 Child RME: 1
As shown above, the potential excess cancer risks quantified in the risk
assessment for the ingestion pathway involving groundwater exposure were
approximately in the 10"5 and 10~7 range for the future and current land use scenarios,
respectively. The largest noncarcinogenic risk was equal to 1, for the child reasonable
maximum exposure future groundwater ingestion pathway. All other noncarcinogenic
risks were below an HI of 0.5.
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An additional consideration when evaluating the site is whether contaminant
concentrations in a drinking water aquifer exceed safe drinking water standards. The
groundwater zones impacted by the chemicals associated with the landfill are currently
being used for domestic and irrigation purposes. Currently, the closest domestic wells
still in use, are near the edge of the plume. If no action is taken at the site, the
contaminant plume would migrate to the domestic wells. Several concentrations of
contaminants detected within the current plume exceed maximum safe drinking water
standards including those for trichloroethylene, tetrachloroethylene and vinyl chloride.
Vinyl chloride is a known human carcinogen. Currently at the site, the average
concentration of vinyl chloride along the point of compliance is 64 ug/l and the
maximum detected concentration is 150 ug/l. The safe drinking water standard for
vinyl chloride is 0.5 ug/l. The chemical specific standards which define acceptable risk
levels (e.g. State and Federal drinking water maximum contaminant levels, MCLs)
have been exceed at this site, and warrant the need for remedial action. Actual or
threatened releases of hazardous substances from this site, if not addressed by
implementing the response action selected in this Record of Decision, may present an
imminent and substantial endangerment to public health, welfare, or the environment.
7.0 Applicable or Relevant and Appropriate Requirements
The following federal regulations have been determined to be applicable or
relevant and appropriate requirements at the Fresno Sanitary Landfill:
Safe Drinking Water Act 40CFR 141.61: MCLs, Provides maximum contaminant
levels (MCLs) for drinking water.
Safe Drinking Water Act 40CFR 144: Underground Injection. Provides
Requirements for Underground Injection Program.
Clean Water Act 33 CFR Part 301 &302: Effluent Limitations. Requires
establishment of technology-based discharge limits for point sources of pollution
Clean Water Act 33 CFR Part 307: Toxic & Pretreatment Standards. Requires
the establishment of pretreatment standards for the control of pollutants to
POTW.
Clean Air Act 40 CFR 61: National Emission Standards for Hazardous Air
Pollutants. Identifies and establishes emission standards for specific chemicals.
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The following state of California regulations have been determined to be
applicable or relevant and appropriate requirements at the Fresno Sanitary Landfill:
Water Quality Control Plan (Basin Plan) for the RWQCB. OCR: Establishes
water quality objectives, including narrative and numerical standards, that
protect the beneficial uses and water quality objectives of surface and ground
waters in the region.
Title 23. Division 3. Chapter 15. Article 123 CCR 2511 (d): Actions taken by or
at the direction of public agencies to clean up or abate conditions of pollution or
nuisance resulting from unintentional or unauthorized releases of waste or
pollutants to the environment are exempt from the requirements in the chapter;
provided that wastes, pollutants, or contaminated materials removed from the
immediate place of release shall be discharged according to Article 2 of this
Chapter; and further, that remedial actions intended to contain such wastes at
the place of release shall implement applicable provisions of this subchapter to
the extent feasible.
Title 23. Division 3. Chapter 15. Article 123 CCR 2510(g): Since the waste at
the site will be contained, the requirement that persons responsible for
discharges at waste management units which are closed, abandoned, or
inactive on the effective date of these regulations may be required to develop
and implement a monitoring program in accordance with Article 5 of this
chapter is applicable.
State Water Resources Control Board Resolution No. 92-49 III G.(As amended
April 21. 1994): Establishes requirements for investigation and cleanup and
abatement of discharges that impact or threaten water quality. Dischargers
must clean up and abate the effects of discharges in a manner that promotes
the attainment of either background water quality or the best water quality that
is reasonable if background is not technically and economically feasible.
State Water Resources Control Board Resolution No. 88-63 ("Sources of
Drinking Water Policy") (as contained in the RWQCB's Water Quality Control
Plan) Specifies that, with certain exceptions, all ground and surface waters
have the beneficial use of municipal or domestic water supply.
Title 23. CCR. §2550.6: Requires monitoring for compliance with remedial
action objectives for three years from the date of achieving cleanup levels.
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Title 23. CCR. §2550.7: Requires general soil, surface water, and groundwater
monitoring.
Title 23. CCR. §2550.9: Requires an assessment of the nature and extent of
the release, including a determination of the spatial distribution and
concentration of each constituent.
Title 23. CCR. §2550.10 : Requires implementation of corrective action
measures that ensure that cleanup levels are achieved throughout the zone
affected by the release by removing the waste constituents or treating them in
place. Source control may be required. Also requires monitoring to determine
the effectiveness of the corrective actions.
Title 22. CCR. Division 4. Chapter 15. Articles 4. 5.5. and 8: Requirements for
public water systems. Includes maximum contaminant levels (MCLs).
Health and Safety Code §25249.5: Title 22. CCR. Division 2. Subdivision 1.
Chapter 3: Prohibits the discharge or release to water or to land of a significant
amount of any chemical known to the State of California to cause cancer or
reproductive toxicity when the chemical will probably pass through a source of
drinking water.
Title 22. CCR. Division 4.5. Chapter 14. Article 6. §66264.90-66264.101:
Groundwater Protection. Creates broad groundwater monitoring and compliance
standards. Includes concentrations standards, monitoring requirements and
corrective action requirements.
Title 22. CCR. Division 4.5. Chapter 14. Article 7. §66264.117 : Closure & Post
Closure. States that monitoring, maintenance and reporting requirements must
continue for 30 years past closure.
Title 22. CCR. Division 4.5. Chapter 14. Article 9. §66264.170-66264.178 :
Containers. Requirements for facilities that store containers of hazardous waste.
Title 22. CCR. Division 4.5. Chapter 14. Article 10. §66264.190 -66264.200:
Tanks. Outlines design and management standards for tanks.
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8.0 Description of Alternatives
Four alternatives, including a limited action alternative were developed for the
groundwater near the site. All the alternatives have some of the same components,
referred to as common elements.
8.1 Common Elements
A description of each of the common elements is presented below. The
institutional controls, well decommissioning and groundwater monitoring program are
elements common to all alternatives. A more elaborate groundwater monitoring
program is required in the active alternatives (alternative 2, 3 and 4). Groundwater
treatment and managing the treated groundwater are common to the active
alternatives only.
Institutional Controls. Institutional controls are non-engineering methods by which
access to contaminated environmental media is restricted. Most institutional controls
are in the form of use or access restrictions. Institutional controls anticipated at the
Fresno Sanitary Landfill will consist of restricting the installation of water supply wells
in the impacted aquifer and limiting site access. Controls on the use of the
groundwater pumped from the contaminated aquifer by existing wells will be
considered. These institutional controls can be enforced by the County governmental
agency or by zoning and deed restrictions.
Well Decommissioning. A series of groundwater supply and monitoring wells in the
vicinity of the site may be allowing cross-contamination between upper and lower
aquifer units, and have been proposed for decommissioning. The wells fall into three
categories.
Former Residential Supply Wells. The four targeted residential supply wells are
located south of the landfill at homes recently purchased by the City (2100,
2142, 2168, and 2188 North Avenue). These wells are no longer needed.
Groundwater Monitoring Wells. The two targeted groundwater monitoring wells
are screened across multiple aquifer units and do not provide useful
environmental data (Wells EW-1 and OW-1).
Water Supply Wells. Three irrigation supply wells are located within or adjacent
to the groundwater plume west of the landfill. Water level measurements
collected during the remedial investigation show that when in operation, these
wells create a downward gradient of flow may result in which drawing
contaminants into deeper aquifer layers. In addition, there are two water supply
wells located on the landfill. Collectively, the use of these wells presents the
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potential for increasing exposure to contaminants in the groundwater and could
draw contaminants from the upper A aquifer into the underlying groundwater
units (Wells U-16, I-4, I-5, 19H-1, and 19H-2).
Groundwater Treatment. The extracted groundwater will be treated to remove
contamination prior to the ultimate disposition of the treated effluent. Treatment of the
groundwater will be performed either at a treatment plant that would be located on-site
at the landfill or at the Fresno Regional Wastewater Facilities (RVWVF). The City of
Fresno has proposed using a two-stage treatment process. The first stage will consist
of an air-stripping unit for removal of volatile organic compounds from the
groundwater. This will be followed by a granular activated carbon (GAG) unit for
adsorption of volatile organic compounds from the off-gas stream. The treatment
system will also include storage tanks, piping, mechanical equipment, and other
materials necessary to process the extracted groundwater. It is anticipated that the
treatment system will be located on City property adjacent to the landfill in the vicinity
of the contaminant plume.
Management of Treated Groundwater. Options for the treated effluent are:
Irrigation either through direct use on the landfill or by farmers in the vicinity of
the landfill, or as a source of water for the irrigation canals.
Discharge into the Fresno drinking water supply distribution system.
Off-site disposal at the Fresno RWWF.
Aquifer recharge through either reinjection or percolation ponds.
Initially, the City of Fresno intends to dispose of the contaminated groundwater
to the Fresno RWWF. Ultimately, after the landfill cap is constructed and there is
vegetation on the landfill, the City intends to use the treated groundwater as irrigation
water for the landfill cover. Effluent standards of the treated water varies depending
on ultimate disposal. The effluent standards are as follows:
Discharge to the Fresno RWWF is considered an off-site discharge which must
comply with the pretreatment requirements of the RWWF.
Discharge to irrigation canals are considered an off-site discharge and would
require an NPDES permit.
Discharge of treated groundwater for re-injection outside of the plume must
meet non-detect effluent levels.
Use of the treated water for irrigation or for percolation ponds must meet the
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effluent limits for land disposal.
Use of treated water for drinking water must meet the requirements of Safe
Drinking Water act. Where appropriate, discharge levels should be set at
drinking water standards including taste and odor requirements.
8.2 Alternative 1 - Limited Action
As part of Alternative 1, all components described in common elements will be
implemented. No further remedial actions will be taken to control groundwater flow
either beyond the landfill perimeter or beyond the current off-site contaminant plume.
Continuing migration would not be prevented in any way as a result of actions
undertaken as part of this alternative other than through natural attenuation.
The groundwater monitoring program currently underway will be continued as a
way of quantifying the impacts associated with no remedial response action. The
monitoring program is described in detail in the Semi-Annual Groundwater Monitoring
Program (COM, 1995a), as modified by EPA comments dated May 2, 1995. The
groundwater monitoring program under Alternative 1 consists of the following
elements:
Semi-annual groundwater monitoring Periodic sampling of the
groundwater will be conducted. The groundwater monitoring system
includes 33 groundwater monitoring wells and 9 residential wells. No
new wells will be drilled under this alternative.
Quarterly water level measurements Water level measurements will
be made on a quarterly basis. Quarterly water level measurements are
carried out on all of the groundwater monitoring wells.
Reporting Reports will be prepared on a semi-annual basis and will
summarize the analytical laboratory results of the semi-annual
groundwater monitoring event and the two previous water level
measurement events.
Periodic evaluation of the monitoring program The groundwater
monitoring program will be evaluated after 5 years of operation.
Modifications to the program may be proposed based on the monitoring
data obtained.
The costs associated with the Limited Action alternative are only those required
to perform the monitoring and periodic review of data from the existing groundwater
monitoring well network. Annual O&M costs are estimated to be $68,000 which result
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in a total present worth value of $1,018,000 over a 30-year post-closure period.
The Limited Action alternative will not meet the clean-up standards for
contaminated groundwater established under either Federal or State requirements
based on existing contaminant concentrations in the A and B aquifers.
8.3 Alternative 2 - Landfill Perimeter Plume Containment and Off-site Plume
Monitoring
Organic compounds are introduced into the groundwater as the leachate formed
in the trash prism infiltrates through underlying soil into the groundwater below the
landfill at the site. The primary objective of Alternative 2 is to isolate this source of
groundwater contamination from impacting downgradient waters. This is
accomplished by creating a hydraulic barrier along the downgradient, western
perimeter of the landfill in the A and B aquifers, and C aquifer, if contamination is
found in the C-zone during the monitoring program. Such a barrier system effectively
prevents the contaminated groundwater located beneath the landfill from mixing with
downgradient waters. In containing the impacted groundwater along the perimeter of
the landfill, Alternative 2 is consistent with the presumptive remedy component of the
groundwater remedial action.
The point of compliance in this alternative is the landfill boundary. This is the
point where leachate-contaminated groundwater will be contained.
Once the landfill perimeter extraction wells are installed and operating, pumping
in a given aquifer will draw down the water in that layer and will create cones of
depression centered around each well. These cones of depression will cause water to
flow toward the extraction wells, from locations both upgradient and downgradient of
the wells. Water downgradient (west-southwest) of a perimeter extraction well can flow
toward the well because of the reversed hydraulic gradient.
Naturally-occurring processes such as volatilization, sorption and
biodegradation play a role in the attenuation of contaminants existing in the off-site
aquifer. In the past, the attenuation rate of these natural processes has not been
sufficient to keep pace with the plume migration rate. However, once the perimeter
extraction system is in operation, there are two factors that are likely to increase the
importance of natural processes in the attenuation of off-site contamination: no
additional contaminant mass will be introduced into the off-site aquifer plume; and, as
the plume migration rate is reduced, naturally occurring processes have more time to
act on and attenuate the existing plume.
This alternative will also include the common elements described in earlier
sections. The groundwater monitoring program currently underway will be enhanced to
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include additional monitoring wells and a more comprehensive sampling frequency of
the wells. The purpose of the monitoring program is to verify the extent of the plume,
to verify the effectiveness of the landfill containment wells and to include additional
domestic wells in the sampling program, if needed. The monitoring program shall also
include reporting to participating oversight agencies and notification of potentially
impacted residents. The details in this monitoring program will be described in detail
in a groundwater monitoring plan. The groundwater monitoring program will be
evaluated after 5 years of operation and during the installation and operation of the
phasing of remedy for alternatives 3 and 4. Modifications to the program may be
proposed based on the monitoring data obtained.
In accordance with EPA guidance for the preparation of feasibility studies (EPA,
1988), costs were developed for a 30-year operating period. The capital cost for
implementing the institutional controls and constructing the perimeter extraction
monitoring and treatment systems is $3,714,000. Annual operation and maintenance
(O&M) costs are estimated to be $453,000 which results in a present worth value of
$6,774,000 over the 30-year remediation period. The total 30-year present worth
value of the Alternative 2 extraction and monitoring systems is $10,488,000. Landfill
perimeter wells may have to be operated for a period greater than 30 years.
Federal or State applicable or relevant and appropriate requirements governing
groundwater clean-up levels will not be achieved within a reasonable time frame under
Alternative 2, because the objective of this alternative is source control and not clean-
up. Volatile organic compounds above regulatory allowable limits will remain in the
plume downgradient of the zone of capture of the perimeter extraction system for
some time prior to being attenuated below the regulatory limits.
Alternative 2 is the presumptive remedy established in EPA guidance on landfill
CERCLA sites (EPA, 1992a; EPA, 1992b).
8.4 Alternative 3 - Landfill Perimeter Plume Containment and Off-site Plume
Containment
The primary objective of the Alternative 3 remedial action is to prevent
contamination of currently uncontaminated portions of the aquifer system. This is
accomplished by preventing the groundwater plume from expanding in both a lateral
and vertical direction. Plume containment is achieved by installing two systems of
groundwater extraction wells. The extraction well systems, designed to act as
hydraulic barriers to groundwater flow, will be constructed adjacent to the western
boundary of the landfill (as in Alternative 2) and along the downgradient edge of the
off-site contaminant plume.
There are two points of compliance in this alternative. The landfill boundary is
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the point of compliance where leachate-contaminated groundwater will be contained.
The current extent of the plume, as defined in the remedial investigation, is the point
of compliance where currently contaminated water will be contained.
The landfill perimeter extraction system component of this alternative will
intercept groundwater passing underneath the landfill and is identical to that described
for Alternative 2. This system will limit additional contaminant mass from impacting
groundwater downgradient of the landfill. The purpose of the plume boundary
extraction system is to limit the movement of the groundwater plume in a
downgradient (southerly and westerly) direction in the A and B zones. The C zone will
be monitored and included in the extraction system, if necessary. The lateral and
vertical extent of the plume is contained such that downgradient water quality is not
impacted.
A groundwater monitoring program will be instituted as described in Alternative
2. The purpose of the monitoring program is to verify the extent of the plume, to
assess the effectiveness of the landfill containment wells and the effectiveness of the
plume containment wells, and to include additional domestic wells in the sampling
program, if needed.
As described above in Alternative 2, once the groundwater extraction systems
begin operation, natural attenuation processes, such as volatilization, sorption, and
biodegradation, will begin to play a more important role in the attenuation of the off-
site contamination. Natural attenuation becomes more important because no
additional mass will be introduced into the off-site aquifer and, as the plume migration
rate is reduced, the naturally occurring processes have more time to act on and
attenuate the existing plume.
In addition to the landfill perimeter extraction wells, it is estimated that 4
groundwater extraction wells from the A aquifer and 4 wells for extraction of
groundwater from the B aquifer will be located to prevent expansion of the off-site
plume. These will be co-located, single completion wells drilled, installed, and
completed as described for the landfill perimeter extraction wells. No estimate for
C aquifer wells was included. However, if contamination associated with the site is
found in the C aquifer above levels of concern, extraction wells will be installed and
operated.
In accordance with EPA guidance for the preparation of feasibility studies (EPA,
1988), costs were developed for a 30-year operating period. The capital cost for
implementing the institutional controls and constructing the perimeter extraction,
monitoring and treatment systems and plume boundary containment and monitoring
systems is $6,375,000. Annual operation and maintenance (O&M) costs for these
extraction and monitoring systems are estimated to be $598,000 which result in a
present worth value of $8,940,000. The total 30-year present worth value for the
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Alternative 3 extraction and monitoring system is $15,315,000.
Alternative 3 will not comply with the State ARAR that requires dischargers to
clean up and abate the effects of discharges in a manner promoting attainment of
either background water quality or the best reasonable water quality if background
quality is not technically or economically feasible as determined in accordance with
State regulations. Although Alternative 3 will remove significant contaminant mass
over time as a result of the combination of the perimeter extraction wells and the
plume boundary extraction wells, the primary objective of this alternative is not to
clean up and abate the effects of the discharge in the water downgradient of the
landfill and upgradient of the plume boundary containment wells.
8.5 Alternative 4 - Landfill Perimeter Plume Containment and Off-site Plume
Restoration
The primary goal of Alternative 4 is to actively restore the contaminated aquifer
downgradient of the landfill to levels that comply with regulatory standards which are
maximum contaminant levels (MCLs) at this site. This is accomplished by extracting
the contaminated groundwater in the region west of the landfill within the existing off-
site plume, in conjunction with landfill boundary extraction wells. This action will allow
the aquifer to be flushed with clean groundwater. Isolating the groundwater flowing
underneath the site with the perimeter extraction system will result in no additional
contaminant mass being added to the off-site plume, thus facilitating restoration of the
aquifer within the off-site plume.
The point of compliance in this alternative is the landfill boundary. This is the
point where leachate-contaminated groundwater will be contained. All groundwater
past this point will be restored to beneficial use.
The extraction well system for this alternative is more extensive than the
system developed under Alternative 3. Additional extraction wells are placed within
the plume for the aquifer restoration remedial action. A groundwater monitoring
program as described in Alternative 3 will also be implemented in Alternative 4.
Alternative 4 was divided into 2 subalternatives in the Feasibility Study. The
division was made based on the clean-up goal, either background or maximum
contaminant levels (MCLs). State regulations (CCR, Title 23, Chapter 15, Article 5)
state that groundwater clean-up goals established for corrective action measures
cannot exceed background water quality unless it is shown that background is
technically or economically infeasible, but in no case can the clean-up levels be set
higher than MCLs. At the Fresno Sanitary Landfill, background levels would be non-
detect. In the Feasibility Study, an analysis was completed on potential clean-up
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levels following the process outlined in the state of California regulation, Section
2550.4 of Article 5, Title 23. The analysis showed that it was technically and
economically infeasible to establish a non-detect level for clean-up. The potential for
the aquifer to be cleaned up to background levels within a reasonable time period is
low. This was demonstrated by evaluating the historical performance of many pump
and treat systems. The general ineffectiveness of pump and treat systems to reach
low cleanup levels are a function of aquifer characteristics which prevent flushing of
specific zones and the difficulty of desorbing the entire contaminant mass from the
aquifer soil particles. Groundwater with volatile organic compounds at maximum
contaminant levels (MCLs) do not represent a risk to public health or the environment
greater than the risks associated with background levels. The cost of and the length
of time to clean-up the aquifer to background levels was estimated to be
approximately 3 times greater and 3 times longer than cleaning up to MCLs.
Costs were developed for a 30-year operating period. The capital cost for
implementing the institutional controls and constructing the extraction, monitoring and
treatment systems under alternative 4 is $7,948,000. Annual O&M costs for the
extraction and monitoring systems are estimated to be $624,000 which results in a
present worth value of $9,329,000. The total 30-year present worth value of the
Alternative 4 extraction and monitoring systems is $17,277,000.
Alternative 4 whose goal is to clean up the groundwater plume to maximum
contaminant levels (MCLs) complies with all applicable or relevant and appropriate
requirements.
8.6 Phased Implementation of the Remedial Action
In an effort to streamline the Superfund process, EPA has begun to encourage
adoption of a new strategy for implementation of remedial action called phasing. An
important benefit of this approach is that data generated during early phases can be
used to refine and enhance later phases of the remedial action. A phased remediation
approach can make best use of site-specific hydrogeologic and geochemical data
collected during early phases of the site remediation program to implement later
actions in the most efficient and effective manner possible. The remedial alternatives
identified and evaluated as part of the feasibility study were designed to facilitate this
concept of phased implementation. The remedial activities in the lower-numbered
alternatives will be implemented first, before components of the next remedial
alternative are implemented. Data will be collected during the operation of each
phase to ensure the objectives of each phase are achieved (e.g. plume is contained
for phase II), and to collect data to optimize the design of the next phase.
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1 - Phase I - landfill perimeter extraction wells
Phase I includes installation and operation of the extraction wells along the
perimeter of the Fresno Sanitary Landfill in order to contain the contaminated
groundwater below the landfill. Groundwater monitoring beyond the landfill perimeter
and beyond the off-site plume will also be undertaken. All other common elements
described above will be implemented in this phase. The data to be collected and
analyzed are as follows:
Water level data to assess whether the landfill perimeter extraction wells
are containing all of the contamination groundwater beneath the landfill.
Water level and water quality data from the monitoring wells and
extraction wells to assess the downgradient extent of the off-site
groundwater plume.
Drawdown data in monitoring wells surrounding the extraction wells to
evaluate the capture zone in order to optimize the design of the phase II
wells, if needed.
Drawdown data in monitoring wells surrounding the extraction wells to
evaluate the efficiency in the capture zone of the landfill perimeter
extraction wells.
Water level data from extraction and monitoring wells to evaluate the
impact of the extraction wells and the effect of on-land discharge of the
treated water on aquifer water levels.
It is anticipated that operation of this phase before moving on to phase II will be
between one to two years.
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2 - Phase II - plume control extraction wells
This second phase of the remediation includes the installation and operation of
the wells to contain the movement of the contaminated groundwater plume. The
landfill perimeter extraction wells from phase I will still be operated. After phase II of
the remedy is fully implemented, the contaminated groundwater plume is fully
contained. Data to be collected and analyzed during this phase is as follows:
Water level data to assess whether the off-site plume is being contained
by the extraction wells.
Water quality data from the monitoring wells and extraction wells to
assess rate of contaminant removal and determine the most effective
way to install and operate phase III wells, if needed.
Water level and quality data from the monitoring wells and extraction
wells to assess rate and amount of contaminant removal from the phase
II wells to determine effectiveness of the phase II system in terms of
timely removal of contaminant.
Drawdown data in monitoring wells surrounding the pumping wells to
assess influence of different pumping rates to efficiently design the
aquifer restoration wells (phase III).
Water quality data from the monitoring wells and extraction wells around
the lateral edges of the contaminated portion of the aquifer near the site
to assess the rate of contaminant removal where groundwater is flushed
through the aquifer system.
The collection of chemical desorption rates is a more time involved process;
therefore, phase II will be operated longer than phase I. It is estimated that phase II
could take between 2 and 5 years to collect sufficient data during phase II before
moving to phase III.
3 - Phase 111 - aquifer restoration
This third and final phase of the remediation includes the installation and
operation of the wells to complete restoration of the aquifer to beneficial use. Phase
and phase II extraction and monitoring wells will still be operated. The data to be
collected and analyzed are as follows:
Water level and quality data from the monitoring wells and extraction wells to
determine effectiveness of the phase III system.
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9.0 Summary of Comparative Analysis
The purpose of this section is to present a comparative analysis of the
alternatives that were developed to remediate the groundwater. The comparative
analysis was made based on nine criteria. This section is organized by evaluation
criteria. The extent to which each of the four alternatives satisfies the criteria will be
compared and contrasted.
9.1 Overall Protection of Human Health and the Environment
Alternatives 2 through 4 (also referred to as the "active alternatives") are
relatively more protective of human health and the environment than the Limited
Action alternative, because contaminants are removed from the aquifer under
alternatives 2 through 4 which reduces the plume toxicity and volume. For instance, as
compared to alternative 1, alternative 2 adds a further level of protection providing
source control and more extensive monitoring of the off-site. Alternative 3 will provide
a higher level of protection, via active containment of the off-site plume. This will
prevent the off-site plume from migrating into clean portions of the aquifer and will not
lead to exposure of currently unexposed populations. Alternative 4 provides the most
extensive level of protection because it restores the aquifer to beneficial use and does
not rely on institutional controls to protect public health.
9.2 Compliance with Applicable or Relevant and Appropriate Requirements
The plume containment achieved under Alternatives 3 and 4 satisfies the
remedial action objective of preventing the plume from moving downgradient and
impacting previously uncontaminated groundwater resources. Alternatives 3 and 4
also establish the conditions where additional groundwater resources will not be
impacted. Alternative 4 is the only alternative that complies with the federal and state
of California's requirement to restore sole-source aquifers to beneficial use.
9.3 Long-Term Effectiveness and Permanence
The perimeter extraction system specified in Alternatives 2 through 4, and the
plume boundary containment system specified in Alternatives 3 and 4, will likely meet
performance objectives. These systems will effectively isolate the off site plume from
the contaminant source and will limit the plume from expanding in a westerly direction.
The institutional controls in the first three remedial alternatives are not as
reliable in preventing access to contaminated groundwater over the long term as
restoring the aquifer to beneficial use (alternative 4). The technologies associated
with groundwater extraction and treatment are dependable when properly operated
and maintained. Alternatives 2, 3, and 4 will require long term operation of the
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extraction and treatment systems.
No long-term effectiveness is accomplished with Alternative 1 because no
controls on contaminant movement are implemented under the Limited Action
alternative. The perimeter extraction system (Alternative 2) prevents additional
contaminant mass from being added to the groundwater downgradient from the site.
However, the volatile organic compounds may spread over a greater area under
Alternative 2 because the plume limits are not actively contained.
9.4 Short-Term Effectiveness
The perimeter extraction and plume boundary containment system specified in
the active alternatives will effectively isolate the contaminant plume within
approximately 3 months of operation. The time frame for operating the landfill
perimeter wells is unknown because it is not known how long leachate will continue to
be formed. The time frame for reaching the clean-up goals established under
Alternatives 4 is also unknown and will be determined during phase II of the remedial
action.
Implementation of all four alternatives will have minimal impacts on the
residential community and will have equivalent minimal impacts on workers in the
short-term. The systems proposed are at a substantial distance from the local
residences. Portions of Alternatives 2, 3 and 4 will be constructed on private property
and implementation of these three alternatives will interfere with the agricultural
operations occurring on these properties.
9.5 Reduction of Toxicitv. Mobility, and Volume Through Treatment
Reduction of toxicity, mobility and volume will be achieved to some degree
within the contaminated portions of the aquifer under each of the alternatives, due to
natural attenuation (including compound dispersion, adsorption, and biodegradation)
which reduces contaminant mass, and therefore contaminant toxicity and volume.
Alternatives 2 through 4 reduce contaminant toxicity and volume to successively
higher degrees since they remove increasing amounts of contaminated water from the
aquifer. Alternatives 2 through 4 also reduce the toxicity and volume of contaminated
groundwater to successively higher degrees through treatment of extracted water.
Alternatives 3 and 4 will reduce off-site plume contaminant volumes more so than
Alternative 2 due to the greater number of wells located in the off-site plume and
higher initial pumping rates under Alternatives 3 and 4.
Alternative 2 reduces contaminant mobility to a moderate degree compared to
Alternative 1 since the perimeter containment wells capture some of the off-site plume.
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The hydraulic gradient in the off-site plume area is also reduced by operation of the
perimeter containment wells; this will decrease groundwater flow rates and therefore
also reduce the migration rate of the off-site plume. Alternatives 3 and 4 reduce
contaminant mobility to about the same degree in the off-site plume.
9.6 Implementabilitv
The Limited Action alternative is readily implemented, requiring the least
number of permits, access easements, or controls to institute. The existing monitoring
well network will be sampled on a periodic basis in a similar manner as being
performed currently.
Alternatives 2, 3, and 4 require the same relative amount of coordination with
the regulatory community. The State agencies governing groundwater clean-ups, the
Central Valley Regional Water Quality Control Board and Department of Toxic
Substances Control, are presently involved in the identification and development of
remedial actions at Fresno Sanitary Landfill.
Alternatives 2, 3, and 4 will be progressively more difficult to implement, due to
the increased number of wells, higher production rates, more extensive piping and
treatment systems required and larger operations and maintenance efforts involved.
Implementation of the three active alternatives require access to private property
located west of the landfill to install and operate plume extraction and monitoring
wells. Plume boundary monitoring wells may be installed up to approximately 1,500
feet west of the site. For Alternatives 3 and 4, an extraction well system will be
constructed on private property in addition to the downgradient monitoring well
network, while the extraction wells for Alternative 2 will be located on City property.
Negotiating construction access agreements and long-term easements, while feasible,
will require effort.
The extraction and treatment technologies specified for Alternatives 2, 3, and 4
use standard well drilling techniques and treatment processes. Air strippers are
commonly used for water treatment applications similar to the Fresno Sanitary Landfill
project. Multiple contractors are available locally with the capability of providing the
services necessary to construct and operate the three active alternatives.
Another element of the implementability criterion is technical feasibility of
achieving the stated remedial objective for each of the alternatives. Because they are
expected to achieve their respective remedial objectives, Alternatives 2 and 3 are
considered to be technically feasible. Although Alternative 4 is a known technology, it
is technically uncertain at this time when the aquifer can be restored to maximum
contaminant levels (MCLs).
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The monitoring well networks proposed for Alternatives 2, 3, and 4 will be
similar for all three alternatives, with well points located immediately downgradient of
both the landfill perimeter extraction system and the downgradient plume boundary.
They are therefore equally implementable.
9.7 Cost
The EPA has defined a 30-year time period on which to calculate costs for the
remedial systems. While costs have been estimated for this time period, it should be
emphasized that the landfill plume containment systems in alternatives 2,3 and 4 may
need to operate for periods longer than 30 years, the plume containment wells in
alternatives 3 and 4 may need to operate for longer than 30 years and alternative 4
may or may not achieve its goal of aquifer restoration within 30 years. The total
present worth life cycle costs for the Limited Action alternative are minimal compared
to the three active alternatives. The $1,018,000 cost is for the semi-annual
groundwater monitoring is conducted using the existing well network, and contains no
capital costs.
Capital costs for the alternatives 2, 3, and 4, range from $3,714,000 for
Alternative 2 to $7,949,000 for alternative 4. Annual costs for the active alternatives
range from $453,000 for Alternative 2 to $624,000 for alternative 4. Annual costs (in
terms of present worth) represent approximately 55 to 65 percent of the total present
worth value of the three active alternatives.
Fresno Sanitary Landfill Feasibility Study
Alternatives Cost Summary
Alternative 1
Alternative 2
Alternative 3
Alternative 4
Description
Limited Action
Source Control
Source Control & Off-
site Plume
Containment
Source Control & Off-
site Aquifer
Restoration
Capital
Costs
$0
$3,714,000
$6,375,000
$7,948,000
Annual
O&M
Costs
$68,000
$453,000
$598,000
$624,000
Present
Worth
$1,018,000
$10,488,000
$15,315,000
$17,277,000
Note: Costs shown in the table are based on a 30-year period of operation.
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9.8 State Acceptance
The Department of Toxic Substances Control, as the lead State agency,
concurs with this remedy. The Regional Water Quality Control Board has submitted
comments during the public comment period and EPA's response to these comments
are included in the Responsiveness Summary.
9.9 Community Acceptance
Comments made by the community during the public meeting centered on the
quality of their drinking water and the health effects associated with the landfill. The
community did not state any opposition to alternative 4.
The City of Fresno made a comment at the public meeting supporting the
phasing in of the alternative and their preference for alternative 3. The City of Fresno
also submitted comments in writing expressing their reasons for supporting alternative
3.
10.0 The Selected Remedy
The selected alternative for the groundwater is Alternative 4, aquifer restoration.
This is because it is protective of human health and the environment and complies
with applicable or relevant and appropriate requirements.
The major components of this remedy are:
Groundwater monitoring;
Abandonment of certain wells;
Institutional Controls during remediation;
Phasing-in of the groundwater extraction system;
Installation and operation of phase I groundwater extraction wells (landfill
perimeter containment);
Installation and operation of phase II groundwater extraction wells (plume
containment);
Installation and operation of phase III groundwater extraction wells
(aquifer restoration);
Analysis of each phase of the groundwater remedy; and
Treatment system for the extracted groundwater and all necessary
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piping.
One of the reasons to phase in the remedy is to collect data to optimize the
design. Design elements such as number of wells, location of wells and pumping
rates will be determined during the remedial design and the remedial action phases.
For cost estimating purposes, it was estimated that ten pumping wells (each tapping
into A aquifer and B aquifer) would be needed; phase I would require 3 extraction
wells; phase II would require 4 additional wells and phase III would require 3 more
wells, preliminary pumping rates for this remedy consist of initially pumping the A
aquifer at 1,500 gpm and decreasing to approximately 320 gpm during the 30-year
operational period. The B aquifer will be initially pumped at 1650 gpm, decreasing to
approximately 400 gpm during the 30-year operational period.
The objective of this remedy is to restore the aquifer to beneficial use in a
timely and cost-effective manner. The aquifer is considered to be restored to
beneficial use when levels are at or below maximum contaminant levels (MCLs). The
MCLs for the chemicals of concern are as follows:
C/ea
n-up Goals for Contaminants of Concern in the Aquifer
Constituent
Trichloroethylene
Tetrachloroethylene
Vinyl chloride
1,1-Dichloroethylene
1,2-Dichloroethane
frans-1 ,2 Dichloroethene
c/s-1 ,2 Dichloroethene
1,2-Dichloropropane
1,2-Dichlorobenzene
1,4-Dichlorobenzene
Benzene
Chlorobenzene
Chloroform
1,1-Dichloroethane
Trichlorofluoromethane
Toluene
MCL Concentration
ug/l (micrograms
per liter)
5.0 ug/l
5.0 ug/l
0.5 ug/l (1)
6 ug/l (1)
0.5 ug/l (1)
100 ug/l
6 ug/l (1)
5 ug/l
600 ug/l
5 ug/l (1)
1 ug/l (1)
70 ug/l
100 ug/i
5 ug/i
150 ug/l
150 ug/i
(1) State MCL is more stringent
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11.0 Statutory Determinations
The selected remedy is protective of human health and the environment,
complies with applicable or relevant and appropriate requirements, and is cost-
effective. This remedy utilizes permanent solutions, to the maximum extent
practicable, and satisfies the statutory preference for remedies that reduces toxicity,
mobility, and volume as a principal element.
A five-year review, pursuant to Section 121(c) of CERCLA, 42 U.S.C. §9621 (c),
will be conducted at least once every five years after the initiation of the remedial
action to ensure the remedy provides adequate protection of human health and the
environment.
11.1 Protection of Human Health and the Environment
The selected remedy is protective of human health and the environment. The
objective of the remedy is to restore the aquifer to beneficial use, so human health is
protected. It does not rely, in the long term, on institutional controls to protect human
health. It also intercepts the leachate before it leaves the perimeter of the landfill,
thereby protecting the environment from future degradation.
11.2 Applicable or Relevant and Appropriate Requirements (ARARs)
The selected remedy will be designed to comply with the identified applicable or
relevant and appropriate requirements. These applicable or relevant and appropriate
requirements include federal, and more stringent, promulgated state and local
environmental and public health regulations.
11.3 Cost-Effectiveness
The selected remedy is the most cost effective remedy which is protective of
human health and the environment, and complies with applicable or relevant and
appropriate requirements. In order to minimize cost of construction and operation of
the aquifer restoration system, EPA has proposed phasing-in the remedy, in order to
collect data which would result in the most cost-effective design and operation.
11.4 Utilization of Permanent Solutions and Alternative Treatment Technologies to the
Maximum Extent Practicable
The selected remedy provides for a permanent solution, one that ultimately
does not rely on institutional controls to protect human health and the environment.
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12.0 Documentation of Significant Changes
The proposed plan for the Fresno Sanitary Landfill site was released for public
comment in July 1996. The proposed plan identified alternative 4, aquifer restoration,
as the preferred alternative. EPA reviewed all written and verbal comments submitted
during the public comment period. Upon review of these comments, it was
determined that no significant changes to the remedy, as it was originally identified in
the proposed plan, were necessary.
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RECORD OF DECISION
Fresno Sanitary Landfill Superfund Site
Fresno, California
EPA ID # CAD980636914
PART III - Responsiveness Summary
1.0 Summary of Major Comments
The theme of several written comments centered on the maximum contaminant
levels (MCLs) for clean-up levels. The State of California, Regional Water Quality
Control Board stated a preference for operating a full aquifer restoration system
before establishing clean-up levels because they believe levels lower than maximum
contaminant levels (MCLs) may be achievable. The City of Fresno submitted several
comments in support of alternative 3, arguing that MCLs as a clean-up level could not
be achieved.
Comments and questions during the public meeting centered on the impact of
the contaminants and of the remedy on their domestic or irrigation wells. No
comments were made in opposition or in support of the proposed remedy except for
representatives of the City of Fresno who stated a preference for alternative 3.
The specific comments and EPA's responses are presented in the following
section.
2.0 Comprehensive Response to All Comments
Comment made by California Regional Water Quality Control Board, Central
Valley Region
1 We have reviewed the July 1996 Proposed Plan (Plan) for addressing affected
ground water at the subject site. The Plan states that the "... preferred remedy
calls for restoring the aquifer to drinking water standards." We consider
USEPA's decision to establish ground water cleanup levels which allow
pollutants to remain in ground water to be premature, since sufficient
information has not yet been provided to demonstrate that it is not economically
or technically feasible to restore the ground water to background levels.
We suggest that USEPA consider developing an interim ROD with cleanup
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levels at background concentrations, until sufficient information is provided by
the City to support cleanup levels that are technically and economically feasible.
Once this information has been developed, a final ROD may be prepared that
includes ground water cleanup levels that have been demonstrated to be
feasible.
EPA Response: EPA acknowledges the uncertainty in setting the clean-up levels.
EPA has learned from other pump and treat aquifer restoration sites that the optimum
technical and economical clean-up level is site-specific and difficult to predict before
remedial action has begun.
When a remedy is selected and documented in a Record of Decision (ROD),
EPA certifies that the remedy selection was carried out in accordance with CERCLA
and to the extent practicable, with the NCP. The NCP requires that the remedy be
protective of human health and the environment, and that it complies with the
applicable and relevant and appropriate requirements ("ARARs1). These ARARs, i.e.,
federal and more stringent State requirements, help set cleanup levels. Setting these
cleanup goals in the ROD is necessary for enforceability and also because ARARs are
frozen at the signing of the ROD.
The State ARAR (Resolution 92-49) that requires cleanup of discharges to
attain background water quality allows for cleanup to best reasonable water quality if
background is not technically or economically feasible. EPA believes the City of
Fresno has provided the necessary demonstration that cleanup to background water
quality is not technically and economically feasible for this site. Based on this
demonstration and site specific information, EPA believes that MCLs are the best
reasonable water quality cleanup level for Fresno Sanitary Landfill.
The State has suggested that EPA consider an interim ROD for this site. The
NCP allows EPA to sign interim Record of Decisions. These documents are for the
purpose of speeding up certain parts of the project and moving into remedial action
phase while the investigation continues on other, more complex parts of the site.
However, interim Record of Decisions must be consistent with the final remedy (NCP
§300.430 (a)(ii)(B)). Signing an interim ROD for the groundwater with the intent of
signing a final ROD after remedial action has been implemented and operated for a
long period of time appears to circumvent the NCP requirement which freezes ARARs
at the time of the signing and misinterprets the NCP's intended use of interim RODs.
Most importantly, EPA believes a clean-up level of MCLs restores the aquifer to
beneficial use and is protective of human health and the environment.
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Verbal comments made after public meeting by a community resident:
2 How will the pumping at the landfill affect the levels of groundwater at my well?
It seems that over time, downgradient water levels will drop and I will have less
water available to me.
EPA Response: The groundwater flow in the vicinity of the landfill is can be affected
by the pumping rates of the many wells in the vicinity, while the groundwater level is
dependent on the volume of water the wells pump, and on the amount of groundwater
recharge through surface water and recharge ponds. With so many variables, it is
uncertain how additional wells in the area will affect the water table. However, based
on the groundwater modeling conducted by the City of Fresno's consultant, the
drawdown from the extraction wells probably will not extend to the commentor's well.
EPA will strive to operate a groundwater extraction and treated water recharge system
that minimizes the impact on adjacent wells.
3 - Comments made by the City of Fresno:
3a The City of Fresno (City) has been working with the U.S. Environmental
Protection Agency (EPA) since 1990 on the closure of the Fresno Sanitary
Landfill (FSL) under the Superfund process. The City has been responsible for
the performance of all the technical work at the site including the development
of the field investigation activities, preparation of the Remedial Investigation
Report that describes the nature and the extent of contamination at the site,
and the formulation of the groundwater remediation alternatives documented in
the July 3, 1996 Feasibility Study Report. The City will continue to take primary
responsibility for the cleanup of the landfill as it procures construction
contractors to install the selected environmental control systems at the landfill.
The City is providing this written comment on EPA's proposed plan for
groundwater cleanup at the FSL because, based on the technical work we
performed in developing, evaluating, and comparing remedial alternatives
against the established criteria, we identified Alternative 3 as the selected for
implementation and not Alternative 4 as EPA is proposing. The rationale for the
City's determination is provided below.
The overall goal of a groundwater cleanup system is to protect public health
and the environment by isolating the contaminated groundwater from exposure
to humans and mixing with impacted groundwater aquifers. This is
accomplished in the following ways:
i. Public Health Protection
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Provision of alternate water supplies.
Prohibition of pumping from the plume for drinking water or agricultural
purposes.
//'. Environmental Protection
Create a barrier that prevents the plume from expanding in either a lateral or
vertical
direction.
Alternative 3, Groundwater Containment, achieves these goals to a similar
degree as EPA's proposed plan Alternative 4, for a cost of approximately
$2,000,000 less over the 30-year time frame examined under the Superfund
process. The cost difference is even greater when it is considered that
Alternative 4 will take at least twice as long as the 30-year period to reach its
goal of aquifer restoration, if restoration is possible at all.
EPA Response: EPA recognizes the effort and the cooperative spirit that the City of
Fresno has put forth on this project. The City's concern for the protection of the
community is evident in the willingness the City has shown in supplying filters or
alternative drinking water to residents even when their well water met safe drinking
water standards.
The City is correct that a primary concern in selection of the remedy is
protection of human health and the environment. The NCR has established protection
of human health and the environment as a threshold criteria. The other threshold
criteria is compliance with applicable or relevant and appropriate regulations. These
two criteria must be met by the alternative in order to be eligible for selection. (NCR
§300.430(f)(i)(A)). EPA contends that alternative 4 is more protective to human health
because it does not rely on institutional controls (see EPA's response to comment 3c).
More importantly, alternative 4 is the only alternative that meets the other threshold
criteria, compliance with applicable or relevant and appropriate regulations.
Therefore, alternative 3 does not meet the threshold criteria to a similar degree as
alternative 4.
The NCR also contains a list of expectations that EPA shall consider when
selecting a remedy (NCR §300.430 (a)(iii)). Two expectations applicable to the Fresno
Sanitary Landfill deal with institutional controls and usable groundwater. The NCR
states " The use of institutional controls shall not substitute for active response
measures (e.g., treatment and/or containment of source material, restoration of
groundwater to their beneficial uses) as the sole remedy unless active measures are
determined not to be practicable..." The NCR also states "EPA expects to return
usable groundwater to their beneficial uses, wherever practicable..." EPA believes
active measures are practicable and warranted for this aquifer which is heavily used
for many purposes. (See EPA response to comment 3e) Based on the direction
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given in the NCR, EPA has determined that restoration should be the goal of the
remedy.
EPA also questions whether alternative 4 would actually be more expensive
than alternative 3 for the entire life of the project. The City would be required to
contain the plume for as long as levels exceed safe drinking water levels. Under
alternative 4, active restoration would result in a shorter time where the City would be
required to operate plume containment wells. Also, not included in the City's claim
that alternative 3 is more cost-effective, is the cost of the loss of resource (useable
groundwater) as well as the additional cost incurred by the residents when they must
drill deeper wells with additional casing or seals to avoid the contaminated water.
3b The risk assessment prepared by EPA dated September 1994, entitled "Human
Health Risk Assessment for the Fresno Sanitary Landfill Superfund Site"
identified ingestion of contaminated groundwater as the contaminant pathway
with the greatest risk to public health. There is no greater risk associated with
ingestion of contaminated groundwater under Alternative 3, as compared to
Alternative 4, over the 30-year time period.
EPA Response: The risk assessment looked at current exposure and future
reasonable maximum exposure. It assumed, in the future scenario that a drinking
water well would draw water from the contaminated plume. Under this scenario the
excess cancer risk was calculated to be 8 x 10"5. However, the risks may have been
underestimated. The analytical data used in the risk assessment was from data
collected from the remedial investigation at the time of the risk assessment. The
purpose of the remedial investigation was to define the extent of the plume. At the
Fresno Sanitary Landfill, the PCE and TCE contaminants are the most mobile;
therefore, they were used to define the extent of the plume. Most of the remedial
investigation monitoring wells were installed at the edge of the PCE/TCE plume and
these wells were frequently sampled. There is evidence that the vinyl chloride plume
is not as extensive as the PCE/TCE plume. Since vinyl chloride is a known human
carcinogen, the reasonable maximum exposure levels should focus on areas where
vinyl chloride is detected. The future reasonable maximum exposure level was
biased towards the part of the plume where the concentrations were lowest.
The purpose of estimating a concentration for a reasonable maximum exposure
is to ensure that the true mean of the entire site is not underestimated. Typically the
95% upper confidence level concentration is used to estimate the mean of the entire
site. This mean can be underestimated if the samples are biased to the edge of the
plume. The diluting out of the hot-spots is most evident in the calculation of risk
associated with vinyl chloride. Current EPA risk assessment practice suggests that
samples used in the risk assessment should be carefully selected to prevent diluting
out the hot-spots. Therefore, for the concentration term in groundwater risk
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assessments, a simple average in the hot-spot can be used in calculating risk. The
average concentration of vinyl chloride along the point of compliance is 64.6 ug/l and
the maximum concentration detected is 150 ug/l. The risk assessment used 2.6 ug/l
as the concentration for vinyl chloride in the future scenario drinking well.
The other component to risk is exposure. What is the likelihood that someone
would drink vinyl chloride at 2.6 ug/l? Under alternative 4, the aquifer is restored to
safe drinking water levels (0.5 ug/l for vinyl chloride). Therefore, it is improbable that
there is human exposure to the contaminants. Alternative 3 relies on institutional
controls to prevent someone from drilling a drinking water well in the contaminated
zone. As discussed in EPA's response to comment 3c, it is possible for this system to
fail; consequently, it is possible for human exposure to vinyl chloride under alternative
3. Therefore, there is a slightly greater risk associated with drinking contaminated
groundwater under alternative 3 then there is under alternative 4.
3c The EPA and state regulators will not allow the installation of new wells for
either potable water or agricultural purposes within the plume. Existing
agricultural wells within the plume are scheduled for destruction prior to
implementation of the groundwater remedial action. Residents with a water
supply that may be impacted by the landfill have already received either bottled
water or a system filter to assure clean water is available for potable purposes.
The City has purchased properties surrounding the landfill, creating a buffer
zone that reduces the number of residents in close proximity to the site. These
actions are instituted for both Alternative 3 and Alternative 4. Public health is
equally well protected under both alternatives.
EPA Response: EPA appreciates the efforts the City has made to protect the
public's health. The effort to install filters or supply alternative water when chemicals
associated are detected in the domestic wells, even when they are well below safe
drinking water standards, demonstrates the City's good faith effort.
However, EPA disagrees that both alternative 3 and alternative 4 are equally
protective. Alternative 4, in the long run, does not rely on institutional controls to
protect human health.
Neither the state of California nor EPA have jurisdiction over installation of wells
in the Fresno Sanitary Landfill vicinity. The government entity with authority to issue
permits and thereby restricting well placement and well construction is the County of
Fresno. Since this Record of Decision calls for institutional controls during the
restoration phase, the City of Fresno will be responsible for notifying the County of
Fresno of the necessary restrictions to protect human health and of any changes in
necessary restrictions. It is assumed that, since the County of Fresno is responsible
to protect the waters of its domain and to protect the health of its citizens, it would
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abide by the recommendations by the City of Fresno.
The reliability of the institutional controls are dependent on several factors. It is
dependent on the communication between the City and the County regarding the
present site conditions and well permit applications in the vicinity. It is also dependent
on the County to impose the necessary restrictions and, in some cases, deny a well
permit. It is also dependent on the citizen applying for the permit to follow permitting
requirements that would not be imposed if the groundwater was restored to beneficial
use. As the City is aware, this process has broken down in the recent past when a
well was installed southeast of the landfill.
3d Environmental Protection
There is no greater potential for the contaminant plume to expand beyond its
boundaries under Alternative 3 than Alternative 4. Both remedial systems are
designed to contain both the lateral and vertical limits of groundwater
contamination. Both alternatives consist of landfill perimeter extraction wells to
intercept contaminant mass migrating from the landfill source and off-site plume
containment wells to prohibit the plume from moving further downgradient. The
Alternative 4 extraction wells within the center of the plume, which constitute
the sole difference between Alternatives 3 and 4, are designed to restore the
aquifer and do not contribute to plume containment.
EPA Response: EPA concurs that the uncontaminated portion of the aquifer is
equally protected under alternative 3 and alternative 4. However, in addition,
alternative 4 goes beyond containing the plume, it restores the contaminated portion of
the aquifer (i.e., environment) to beneficial use.
3e "Alternative 4 Objectives Are Unachievable"
The City would view the selection of the Alternative 4 remedy differently if the
aquifer could be restored to drinking water standards within a reasonable time
period. Converting a contaminated water supply to a useable resource is a
positive goal. However, it is estimated that it would take 63 years to cleanup the
A aquifer to drinking water standards based upon groundwater modeling work
documented in the Feasibility Study Report. This time period assumes that all
groundwater pumped was contaminated. In actuality, the pumping system will
recover uncontaminated groundwater as well as the contaminated groundwater.
Because the volume of clean water was included as part of the total flushing
volume estimates, the actual clean-up time will be longer than the 63 years.
A review of the history of pump-and-treat systems indicated that cleanup to
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maximum contaminant levels (MCLs) may not be attainable ever. As
documented in Appendix A of the Feasibility Study report, many studies have
been performed evaluating the effectiveness of pump-and-treat technologies in
an attempt to identify the conditions in which the system applications are most
effective. Two studies, The Effectiveness of Groundwater Pumping as a
Restoration Technology by C.B. Doty, 1991 and the EPA's 1992 Evaluation of
Ground-Water Extraction Remedies, Phase II, evaluated 28 separate sites.
Seventeen of the 28 sites had aquifer restoration as the cleanup goal, defined
as cleanup to, or below, the MCLs. The conclusion of the studies is that
cleanup times were underestimated by three times the original estimate. In
addition, only one of the 28 sites was demonstrated to have achieved aquifer
restoration, with the other sites unable to achieve the cleanup goals established
at MCLs and lower.
Several factors have been identified which may inhibit the attainment of the low
cleanup goals established at the FSL for Alternative 4.
Heterogeneous aquifers have zones of high permeability that develop
preferential pathways for the flushing water. Contaminants in low permeable
materials do not come in contact with the volume of water contacted in the
higher permeability zones. Contaminant transport from the low permeability
materials is then driven by diffusion mechanisms which result in much slower
contaminant release than through flushing action.
Zones of immobile water exist within the soil grain. These zones are present
independent of a material's permeability, and are a function of the soil grain
structure. Once again, contaminants from these areas of immobile water move
by diffusion and not by flushing action.
A portion of the contaminant is released very slowly from the aquifer material.
The contaminant adheres strongly to the soil particles and desorbs at very slow
rates, if at all.
In conclusion, significant evidence exists that the aquifer restoration goals
established under Alternative 4, cleanup to MCLs, are difficult to attain in a
reasonable time period; or may not be achievable at all. Therefore, there is no
incremental benefit to Alternative 4 over Alternative 3, since both alternatives
contain the plume to the same extent.
EPA Response: The commentor cites two reasons supporting the assertion that
MCLs cannot be achieved at the site, the results of their modeling and two studies,
The Effectiveness of Groundwater Pumping as a Restoration Technology by C.B.
Doty, 1991 and the EPA's 1992 Evaluation of Ground-Water Extraction Remedies.
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Phase II. While it is generally accepted that aquifer source areas cannot, under
many circumstances, be restored to beneficial use, it has been demonstrated at pump
and treat sites (including the sites in these studies) that the distal portions of the
plume can be restored to safe drinking water standards, especially in situations where
the source was removed. The situation at the Fresno Sanitary Landfill has many
factors that promote the likelihood that MCLs can be achieved beyond the boundary of
the landfill:
The source will be contained at the boundaries of the landfill and will no longer
act as a source of groundwater contamination downgradient of the landfill. This
will be achieved by extraction wells along the perimeter of the landfill which will
intercept leachate contaminated groundwater before it can migrate to the
aquifer. Restoration is not required in the groundwater directly beneath the
landfill. It was this type of area (source area) that the aforementioned studies
indicated could not be restored to beneficial use.
The concentrations of TCE and PCE in the off-site contaminated groundwater
plume are relatively low compared to their solubility. When concentrations of
contaminants are high relative to their solubility, it is more likely that the
chemicals move or diffuse to the less mobile portions of the aquifer. This is due
to the higher concentration gradient present with high concentrations. Low
concentrations tend to stay soluble in the groundwater
Most of the contaminants of concern are chemically-structures such that they
are less likely to sorb on to soil particles and prefer to remain soluble in water.
The commentor also cited the modeling effort which indicated 63 years time
frame for restoration. EPA has always questioned the predictive quality of the
groundwater model for this site. The data collected for the remedial investigation has
been sparse and the geological cross-sections have been greatly simplified to support
a comprehensive model. A more apt use of this groundwater model is to aid in the
design of the well extraction system.
In conclusion, as the commentor mentions, there are some general conclusions
in literature that tend to suggest attaining MCLs would be difficult to achieve, but there
are also factors at the site that indicate MCLs are a reasonable goal. Lack of site-
specific information and inconclusive general information suggests that a phased
approach to aquifer restoration will provide site-specific data needed to predict time
frames to restoration and how best to achieve them.
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3f The City should not be required to implement a remedial action with an
objective which cannot be achieved. It is irresponsible for the City to burden its
citizens with the financial responsibility of a program whose success is in doubt
from the start.
It is recommended that Alternative 3 be selected as the proposed plan because
it is equally protective of public health and the environment as Alternative 4, at
a 30-year cost of approximately $2,000,000 less than Alternative 4.
EPA Response: EPA is sensitive to the City's dual responsibility of financial
prudence and protecting the health of the people of Fresno. As discussed in EPA's
response to the previous comment, there is uncertainty in how the aquifer system will
respond during remediation. There are factors that indicate restoring to MCLs may
not be feasible and there are factors that indicate restoration is possible. That is one
of the reasons why EPA has proposed phasing in the remedy. If, as the City
presumes, the aquifer cannot be restored, the data collected in the plume containment
phase would show that active restoration phase is not practicable. At that point, the
City could apply for a technical impracticability waiver. More importantly, the City
would not have spent any more money than if alternative 3 had been chosen.
EPA also questions whether alternative 4 would actually be more expensive
than alternative 3 for the entire life of the project. The City would be required to
contain and monitor the plume for as long as levels exceed safe drinking water levels.
Under alternative 4, active restoration would result in a shorter time that the City must
operate the plume containment wells. Also, not included in the calculating the cost of
alternative 3 is the cost of the loss of resource (useable groundwater) and the
additional cost incurred by the residents when they must drill deeper wells with
additional casing sealed to avoid the contaminated water.
Restoring the aquifer to unrestricted use is the best way to protect the health of
the community. EPA believes that the most cost-effective plan would be to phase in
the remedy, in order to optimize the design in each subsequent phases.
3g The City is in agreement with the EPA that the selected remedy should be
implemented in a phased approach. Observations of the aquifer response to the
pumping of the source control extraction wells will provide information valuable
in siting additional wells. Operational data developed during the initial stage of
the remedy such as optimum pumping rates, well draw down, and zone of
capture, can be used to effectively develop subsequent phases of the system. It
is important that a sufficient length of time is allowed for operation of the initial
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phase of the project to allow the necessary information to be obtained. It is
especially critical to obtain operational field data which supports an achievable
cleanup goal prior to construction of the entire Alternative 4 system. Appropriate
phasing of the project will result in the construction of a system which can fulfill
project goals, protection of public health and the environment, in a cost-effective
manner.
The City is committed to continue working with the EPA on the closure of the
FSL in a manner which protects public health and the environment. Efforts to
accelerate the schedule for the installation of the groundwater remedial action,
and other construction aspects of the projects, should be encouraged.
EPA Response: EPA concurs with the City and looks forward to working on the
remedial design and remedial actions at the site with the City. EPA encourages all
efforts to accelerate the project and will help the City achieve this objective, wherever
possible.
4 - Comment made by a neighbor during the public meeting
What is in my well? How does the contamination get to me while I shower? I
don't think the City has changed the filter on my system
EPA Response: The information that EPA has for your well indicates that it was
sampled in July 1992, March 1993, August 1993, May 1994, May 1995 and November
1995. Your well water was tested for a full range of chemicals. Three chemicals have
been detected in your well at levels below safe drinking water levels. These
chemicals are tetrachloroethylene (PCE), trichlorofluoromethane and
dichlorodifluormethane. PCE is a suspected human carcinogen, which means there is
some evidence that PCE may cause cancer. The levels of PCE in your well have
been consistently 3 ug/l; the safe drinking water level is 5 ug/l. The other two
chemicals, trichlorofluoromethane and dichlorodifluormethane, are less hazardous
chemicals. Trichlorofluoromethane has been found at a maximum concentration of 14
ug/l in your water and the safe drinking water level for this chemical is 150 ug/l.
Dichlorodifluormethane has no legal safe drinking water standard; however, a safe
level recommended by scientists has been established at 390 ug/l.
Dichlorodifluoromethane has been detected at about the 10 ug/l range.
The well water is collected for sampling before it runs through the filter. So the
chemical levels discussed above are not the levels that are in your drinking water.
The City of Fresno has informed EPA that they have installed a filter at your wellhead
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and established a frequent service program for that filter system. The filter was last
serviced on June 1, 1996 and is scheduled for the next service on September 1, 1996.
Having the water filtered before it enters your home, protects you from all types of
contact including drinking water and showering.
The chemicals at the Fresno Sanitary Landfill are volatile. That means during
showering, the chemicals in the shower water can easily evaporate and the person
showering can breathe the chemicals. EPA looks at all possible exposures, not just
drinking water, when evaluating the impact on humans. Therefore, we included
showering in the analysis. We found out that the drinking water pathway of exposure
is a far greater health concern than showering. Again, the filter on your wellhead will
protect you from both types of exposure.
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