SEMS-RM DOCID # 100025373
FIFTH FIVE-YEAR REVIEW REPORT
FOR
HASSAYAMPA LANDFILL SUPERFUND SITE
MARICOPA COUNTY, ARIZONA
2
<
3D
O
\
&
O
z
LU
O
T
PREPARED BY
U.S. Army Corps of Engineers, Seattle District
FOR
U.S. Environmental Protection Agency
Region 9
Approved by: Date:
AMrci EC Digitally signed by
rAIXIVJLLI—J ANGELES HERRERA
H ERR ERA Date: 2021.09.07 14:55:49
Angeles Herrera, Assistant Director
Federal Facility and Site Cleanup Branch
Superfund and Emergency Response Division
U.S. Environmental Protection Agency. Region 9
-------
[This page is intentionally left blank.]
-------
Executive Summary
This is the fifth Five-Year Review of the Hassayampa Landfill Superfund Site (Site) located in
Maricopa County, Arizona. The purpose of this Five-Year Review is to review information to
determine if the remedy is and will continue to be protective of human health and the environment.
Maricopa County formerly operated a 47-acre municipal solid waste landfill which included a 10-acre
area in the northeast portion of the landfill used for the disposal of hazardous wastes. The hazardous
wastes were disposed in unlined pits in the landfill under the direction of the Arizona Department of
Health Services, from April 1979 to October 1980. In 1981, under the Resource Conservation and
Recovery Act Open Dump Inventory Program, Arizona Department of Health Services installed three
groundwater monitoring wells at the Hassayampa Landfill. Groundwater samples collected from one
of these wells was found to be contaminated with volatile organic compounds. The 10-acre portion of
the 47-acre municipal landfill where hazardous wastes are known to have been disposed, as well as
any areas where site-related contaminants have come to be located was designated a Superfund Site
and listed on the National Priority List in July 1987. The landfill continued to accept non-hazardous
wastes for disposal until 1997.
In the 1992 Record of Decision, the Environmental Protection Agency selected the remedy for the Site
to remediate the groundwater and vadose zone (including soil and soil vapor above the water table)
contamination. The groundwater component of the remedy includes extraction of contaminated
groundwater, treatment of the water using air stripping technology, reinjection of the treated water
back into the groundwater in the vicinity of the Site, and continued groundwater monitoring to
measure the effectiveness of the remedy to protect long-term human health and the environment. The
vadose zone component of the remedy includes capping the 10-acre hazardous waste area of the
landfill using a cap that complies with the substantive capping and maintenance requirements for the
Resource Conservation and Recovery Act. In addition, the vadose zone component of the selected
remedy includes performing soil vapor extraction at all locations at the Site where soil vapor levels
exceed cleanup standards, treat the extracted soil vapor using vapor phase carbon adsorption or
catalytic oxidation technology, and implementing access and deed restrictions.
In 1994, the Hassayampa Steering Committee (composed of various companies responsible for the
cleanup) implemented the remedy components including: operating the groundwater extraction and
treatment system; placing a cap over the 10-acre hazardous waste disposal area; and implementing
engineering and institutional controls in the form of fencing and land use restrictions.
The initial soil vapor extraction system, designed to use catalytic oxidation technology for treatment of
the soil vapor, was constructed and operated intermittently between 1996 and 1998. After termination
of the soil vapor extraction system in September 1998, subsequent monitoring data indicated an
upward trend in the size and concentration of the vadose zone vapor plume. The Hassayampa Steering
Committee installed a new soil vapor extraction system in 2006 using a proprietary cryogenic
treatment technology combined with carbon polishing to treat the contaminated soil vapor. In 2009,
the Environmental Protection Agency signed the Explanation of Significant Differences # 1
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
i
-------
determining that new performance standards were to be based on calculations using the State
regulatory standards and Federal guidance for soil screening levels and converted to soil vapor levels
at equilibrium. Due to the recent developments in the technology since the 1992 Record of Decision,
the Explanation of Significant Differences # 1 also allows for use of a third type of soil vapor
extraction system technology that is more environmentally protective (cryogenic proprietary
technology). The specific calculations used to drive the new soil vapor performance standards and
revised soil vapor standards for each analyte are included in the Explanation of Significant Differences
#1.
The Environmental Protection Agency updated the Site conceptual model in 2013 to acknowledge soil
vapor transport, not leaching, as the principal pathway for volatile organic compounds impacting the
groundwater. The Hassayampa Steering Committee conducted a pilot test in 2015 to evaluate the
efficiency and cost-effectiveness of changing from the cryogenic treatment system to carbon treatment
for the volatile organic compound-contaminated soil vapor. The results of the pilot test indicated that
changing to the carbon treatment was feasible and the Hassayampa Steering Committee switched to
the carbon treatment for soil vapor in 2016.
In May 2016, the Environmental Protection Agency signed an Explanation of Significant Differences
#2 to update the soil vapor performance standards based on the vapor transport model rather than the
leaching model and clarified the remedial action objectives for the Site:
Groundwater Remedial Action Objectives
• Prevent human exposure to groundwater contaminated by Site contaminants above maximum
contaminant levels and, for contaminants that have no maximum contaminant levels, above
Health-Based Guidance Levels established by Arizona.
• Restore groundwater throughout the Site to concentrations at or below the maximum
contaminant levels and Health-Based Guidance Levels for the Site contaminants.
Soils/Soil Vapor Remedial Action Objectives
• Prevent human ingestion of, or contact with, soil or waste contaminated with Site
contaminants that represent an unacceptable exposure.
• Prevent leaching or vapor transport of Site contaminants from soil and waste in the vadose
zone to groundwater by attaining and maintaining soil vapor concentrations below soil vapor
performance standards that are protective of the groundwater quality and will not result in
degradation of groundwater at concentrations above maximum contaminant levels or health-
based guidance levels at the Site boundary.
The remedy is functioning as intended. Site contaminants in groundwater continue to exceed
groundwater cleanup standards and soil vapor volatile organic compound concentrations periodically
exceed the current soil vapor performance standards in monitoring wells near the source area,
however, the concentrations in both media are generally decreasing. The groundwater remediation
system may need to be operated for decades to cleanup groundwater to beneficial uses and
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
optimization measures will need to be evaluated in the future. There have been no changes to
Applicable or Relevant and Appropriate Requirements that effect the protectiveness of the remedy.
The remedy at the Hassayampa Landfill Superfund Site is protective of human health and the
environment. The soil vapor extraction system and landfill cap are successfully preventing vapor
transport of Site contaminants from the vadose zone to groundwater and the groundwater remediation
system is preventing further migration of Site contaminants in groundwater. Engineering and
institutional controls prevent unacceptable exposure to Site contaminants in soil and groundwater.
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Table of Contents
Executive Summary i
List of Figures v
List of Tables v
List of Abbreviations vi
1. Introduction 1
1.1. Background 3
1.2. Physical Characteristics 3
1.3. Hydrogeology 7
2. Remedial Actions Summary 8
2.1. Basis for Taking Action 8
2.2. Remedy Selection 8
2.3. Remedy Implementation 11
2.4. System Operations/Operation and Maintenance, and Optimization 12
3. Previous Five-Year Review Protectiveness Statement and Issues 14
3.1. Work Completed at the Site During this Five-Year Review Period 14
4. Five-Year Review Process 16
4.1. Community Notification and Site Interviews 16
4.1.1. Five-Year Review Public Notice 16
4.1.2. Site Interviews 17
4.2. Data Review 18
4.2.1. Groundwater 18
4.2.2. Soil Vapor 21
4.3. Site Inspection 24
5. Technical Assessment 25
5.1. Question A: Is the remedy functioning as intended by the decision documents?.... 25
5.2. Question B: Are the exposure assumptions, Toxicity Data, Cleanup Levels, and
Remedial Action Objectives Used at the Time of Remedy Selection Still Valid? 26
5.3. Question C: Has Any Other Information Come to Light That Could Call Into
Question the Protectiveness of the Remedy? 27
6. Issues/Recommendations 27
6.1. Other Findings 27
7. Protectiveness Statement 28
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site iv
-------
8. Next Review 28
Appendix A: List of Documents Reviewed 29
Appendix B: Site Chronology 31
Appendix C: Data Review 33
Appendix D: Applicable or Relevant and Appropriate Requirements Assessment ...45
Appendix E. Toxicity Assessment 48
Appendix F: Public Notice 49
Appendix G: Interview Forms 50
Appendix H: Site Inspection Report and Photos 64
List of Figures
Figure 1. Location Map 5
Figure 2. Detailed Map of the Former Disposal Pit Areas in the Northeast Corner of the
Hassayampa Landfill 6
Figure 3. Conceptual Site Stratigraphy of the Upper Alluvium Unit Showing Pit 1,
Relationship of the Buried Basalt Flow and Units A and B 7
Figure 4 Monitoring and Extraction Well Locations 19
Figure 5. Maximum Groundwater Exceedances from 2015 through 2020 (units in |jg/L) 20
Figure 6. Groundwater Pump and Treat Mass Removal 21
Figure 7 Location of Soil Vapor Extraction Wells 22
Figure 8. Soil Vapor Extraction (SVE) System Mass Removal 23
List of Tables
Table 1. Five-Year Review Summary Form 2
Table 2. Summary of Decision Documents 8
Table 3. Record of Decision Groundwater Cleanup Standards 9
Table 4. Soil Vapor Performance Standards from the Explanation of Significant Difference
#2 11
Table 5. Soil Vapor Exceedance During the Reporting Period 24
Table 6. Protectiveness Statement 28
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
v
-------
List of Abbreviations and Acronyms
ARAR
applicable or relevant and appropriate requirements
bgs
below ground surface
GRS
groundwater remediation system
EPA
United States Environmental Protection Agency
lbs
pounds
Site
Hassayampa Landfill Superfund Site
SVE
Soil Vapor Extraction
SVPS
Soil Vapor Performance Standards
l-ig/L
micrograms per Liter
voc
volatile organic compound
vi
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
1. Introduction
The purpose of a Five-Year Review is to evaluate the implementation and performance of a remedy to
determine if the remedy will continue to be protective of human health and the environment. The
methods, findings, and conclusions of reviews are documented in Five-Year Review reports. In addition,
Five-Year Review reports identify issues found during the review, if any, and document
recommendations to address them.
The U.S. Environmental Protection Agency (EPA) is preparing this Five-Year Review pursuant to the
Comprehensive Environmental Response, Compensation, and Liability Act Section 121, 40 Code of
Federal Regulation Section 300.430(f)(4)(h) of the National Contingency Plan and EPA policy.
This is the fifth Five-Year Review for the Hassayampa Landfill Superfund Site (Site). The triggering
action for this statutory review is the signing of the previous Five-Year Review on September 26, 2016.
The Five-Year Review has been prepared because hazardous substances, pollutants, or contaminants
remain at the Site above levels that allow for unlimited use and unrestricted exposure.
The Site was not officially divided into separate operable units. However, two separate media remedy
components were selected in the 1992 Record of Decision and implemented at the Site, one for soil vapor
and one for groundwater. This review assesses the status and performance of both the groundwater and
soil vapor remedies, including the landfill cap, as well as the engineering and institutional controls that
are intended to address access restrictions and land use at the Site.
The Hassayampa Landfill Superfund Site Five-Year Review was led by Nadia Hollan Burke, EPA Region
9 Remedial Project Manager. Participants included Cynthia Wetmore, EPA Superfund Five-Year Review
Coordinator, and from the U.S. Army Corps of Engineers: Rebecca Rule, Project Manager; Jake
Williams, Project Manager; Jeff Weiss, Hydrogeologist; and Katie Richwine, Physical Scientist. The
review began on November 23, 2020.
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
1
-------
Table 1. Five-Year Review Summary Form
SITE IDENTIFICATION
Site Name:
Hassayampa Landfill Superfund Site
EPA ID:
AZD980735666
Region: 9
State: AZ
City/County: Hassayampa/Maricopa County
SITE STATUS
National Priorities List Status: Final
Multiple Operable Units? No
Has the site achieved construction completion? Yes
REVIEW STATUS
Lead agency: EPA
[If "Other Federal Agency", enter Agency name]:
Author name (Federal or State Project Manager): NadiaHollan Burke
Author affiliation: EPA
Review period: 11/23/2020 - 7/28/2021
Date of site inspection: 7/13/2021
Type of review: Statutory
Review number: 5
Triggering action date: 9/26/2016
Due date (five years after triggering action date): 9/26/2021
2
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
1.1. Background
The Hassayampa Landfill Superfund Site (Site) is owned by Maricopa County and began operation in
1961. It is located in the southeast quarter of Section 3, Township 1 South, Range 5 West, Maricopa
County, Arizona approximately 10 miles west of Buckeye, Arizona. The Site was authorized to receive
unrestricted types of waste under a manifest program operated by the Arizona Department of Health
Services in response to an "extreme emergency" that resulted from the Arizona Department of Health
Services ban on the disposal of industrial waste at the City of Phoenix landfills. Under the manifest
program, a wide range of hazardous wastes were approved for disposal at the Hassayampa Landfill. The
Arizona Department of Health Services requested that Maricopa County accept hazardous waste at the
Hassayampa Landfill for a 30-day period beginning on April 20, 1979. The initial 30-day period was
granted several extensions that ultimately granted the Site authorization to accept hazardous waste for an
18-month period from April 20, 1979 to October 28, 1980 (EPA, 1992). The unlined pits were
subsequently covered with native soil and restored to grade. Based on a review of the Arizona
Department of Health Services manifests, approximately 3.4 million gallons of hazardous liquid wastes
and 4,150 tons of solid wastes were disposed of in a series of five unlined disposal pits at the Site.
Disposal to the municipal landfill ceased in June 1997.
The contamination at the Site is primarily associated with the known disposal pits. Pit 1 and the Special
Pits area received the majority of the hazardous wastes containing volatile organic compounds such as
trichloroethene, 1,1-dichloroethene, dichloromethane, 1,2-dichloropropane, tetrachloroethene, and 1,1,1-
trichloroethane. Pit 1 is the primary location of the contaminant impacts to both the soil and the
groundwater (highest level of soil contamination detected at 60 feet deep). Volatile organic compounds
have been detected in soil and soil vapor in the unsaturated soils both above and below a basalt layer
located approximately 60 feet below ground surface (bgs).
1.2. Physical Characteristics
The Site is located approximately 40 miles southwest of Phoenix and approximately three miles northeast
of Arlington, in Maricopa County, Arizona (Figure 1). The Hassayampa Landfill hazardous disposal area
consists of 10 acres, located within the northwest section of the former 47-acre Hassayampa Landfill
operated by Maricopa County (Figure 2). The Hassayampa River is located approximately one mile east
of the Site and flows completely underground in this river section. Drainage washes to the Hassayampa
River are located to the east of the Site. The Site is outside the regulatory floodway of the Hassayampa
River. The Gila River, Robbins Butte Wildlife Area, and Buckeye Hills Regional Park are the nearest
environmentally sensitive areas, approximately three miles south of the Site.
Surrounding land use has not changed significantly since the 1992 Record of Decision was signed and
includes mostly desert (undeveloped) land to the west and south with cultivated lands to the east of the
Hassayampa River. Vegetation is sparse and includes creosote and salt bush high desert ecosystems.
There are residential houses approximately one mile west of the Site, Hickman's Egg Ranch to the
immediate southwest, and Hickman's Auto Shop to the northwest. In the last five years, Hickman's
Family Farms has expanded its egg production facility, added a waste drying facility to produce fertilizer
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
3
-------
for nearby farms. In 2010, Maricopa County established a new transfer station at the closed municipal
solid waste landfill northwest of the Site. The Site is secured by a fence and is not accessible to the public.
Regarding groundwater use, wells within three miles of the Site provide drinking water to approximately
350 people and irrigation for 2,800 acres of farmland. There are approximately 49 wells within a one-mile
radius of the Site, 22 of which are downgradient of the Site. The nearest downgradient groundwater wells
are about 2,500 yards south of the Site located on the Hickman's Egg Ranch, operated by Hickman's
Family Farms. One of the wells has been installed within the last five years. These production wells are
pumped from a greater depth than the contaminated groundwater aquifer at the Site.
4
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Hassayampa Landfill
Superfund Site
Hassayampa Landfill
Superfund Site
o
NORTH
Figure 1. Location Map for the
Hassayampa Landfil Superfund Site
Hassayampa Landfill Superfund Site
Maricopa County. Arizona
Approximate Boundary of
Hassayampa Sanitary
Landfil
Source: Fourth Five-Year Review for the Hassayampa Landfill Superfund Site, Figure 1. EPA, 2016.
Figure 1. Location Map
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
5
-------
HAS SAY Aid PA
SANITARY-LANDFILL
(dosed: covered 91
with earthen cap)
Explanation sktto*y mv? t south rams? «r
r \ DISPOSAL PIT Locaiiofti and oounaares tar Pus 1.2. 3a. 3c>. 3c. 4d. and 4c
\ n 1 \ 'five 3e»m-neo aooroomatety based on trencnng operators
J Loealona ana OouncarM to Otfet osapoia pAaareoasea on anaiyas
tit a January 26.1961 aanal pnoto and on rapofli Locators and
DOunaanes are ler*at/«e and appro* male
Source: Fourth Five-Year Review Report for the Hassayampa Landfill Superfund Site, Figure 3, EPA, 2016.
Figure 2. Detailed Map of the Former Disposal Pit Areas in the Northeast Corner of the
Hassayampa Landfill
6
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
1.3. Hydrogeology
The Site lies within the drainage area of the Hassayampa River but is outside of the 100-year floodplain.
The Hassayampa River is located approximately one mile east of the Site. The Site is located in an
alluvial-filled basin, which has been influenced by the nearby river and the Arlington Mesa (Quaternary
basalt flows). A regional aquifer consisting of basin-fill deposits underlies the Site and comprises the
principal source of groundwater to wells in the area. The basin-fill deposits have been classified in order
of increasing depth into the Upper, Middle, and Lower Alluvium units. The Upper Alluvium unit is
subdivided into the Upper Alluvial Deposits Unit, Basaltic Lava-flow Unit, Unit A (fine-grained) and
Unit B (coarse-grained) (Figure 3). Unit A and Unit B are both considered to be water-bearing zones
within the same aquifer. There is a limited hydraulic connection between Unit A and Unit B based on the
Unit B water levels not responding to pumping in Unit A and the different water quality between the two
units. The regional groundwater flow direction is generally to the south-southwest in Units A and B. The
groundwater flow direction in Unit A is generally to the south, and more southeast during pumping
conditions. The current water table occurs at a depth of approximately 80 feet bgs in the silts and fine
sands of Unit A. Unit B is composed of somewhat coarser materials than Unit A and is typically
encountered at about 100 feet bgs and has a thickness of over 100 feet. Unit B is a productive aquifer in
the region. Groundwater flows in Unit A are a few tens of feet per year and in Unit B are approximately
200 feet per year.
Unit A UnitB
monitor monitor
well well
Unit A
monitor
well
Source: Fourth Five-Year Report for the Hassayampa Landfill Superfund Site, Figure 4, EPA, 2016.
Figure 3. Conceptual Site Stratigraphy of the Upper Alluvium Unit Showing Pit 1, Relationship of
the Buried Basalt Flow and Units A and B.
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
7
-------
The shallow subsurface at the Site includes two general zones in the zone of unsaturated soils (vadose
zone): an upper coarse-grained zone and a lower fine-grained zone (Hargis + Associates, Inc., and
Geosyntec Consultants 2013). The coarse-grained zone generally extends from ground surface to
approximately 30 feet bgs. The fine-grained zone extends from approximately 30 to 60 feet bgs and
consists predominately of silts and fine sands. Beneath the fined-grained zone, at approximately 60 feet
bgs, there is a basaltic lava flow unit approximately 20 feet thick which tapers out or is not present at the
northern end of the Site. This basalt flow originated from Arlington Mesa to the south. An unsaturated
zone, approximately 10 feet thick, lies beneath the basalt unit.
2. Remedial Actions Summary
2.1. Basis for Taking Action
The unlined waste pits received volatile organic compounds, heavy metals, solvents, pesticides, petroleum
distillates, oil, acids, bases, cesspool and septic tank wastes, and lime wastes which contaminated the soil.
Affected media at the Site include soil, groundwater, soil vapor, and air. The human health and ecological
risk assessments summarized in the Record of Decision found that while risk for ecological receptors was
low, significant health risks may exist for individuals who ingest the contaminated groundwater, contact
hazardous wastes present in several of the trenches and pits, and/or breathe air on or near the Site. Risks
were significant for all residential and occupational exposure scenarios. The basis for taking action was
due to the threat of exposure to groundwater contaminants as a result of future off-Site migration of
contaminated groundwater, and the threat of exposure to contaminated waste and soil under the
residential and commercial/industrial scenarios.
2.2. Remedy Selection
Several decision documents that establish and clarify the selected remedy for the Site have been issued
over the years. Table 2 summarizes the content of these decision documents.
Table 2. Summary of Decision Documents.
Decision Document
Date
Summary
Record of Decision
August 1992
Selected the remedies for cleanup of groundwater and soil vapor in
the vadose zone at the Site.
Explanation of Significant
Differences # 1
December 2009
Established revised soil vapor performance standards based on a
leaching model.
Explanation of Significant
Differences #2
May 2016
Revised the soil vapor performance standards based on a vapor
transport model and established the remedial action objectives for
the Site.
EPA issued a Record of Decision for the soil and groundwater Site contaminants on August 6, 1992. The
remedy selected by EPA in the 1992 Record of Decision includes:
• Groundwater extraction, treatment, reinjection, and monitoring;
• Soil vapor extraction and treatment;
• A multi-layer cap with a geomembrane liner over the 10-acre hazardous waste disposal area; and
• Deed and access restrictions.
8
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
For groundwater cleanup standards, EPA selected the federal drinking water standards for contaminants
with drinking water standards. For those contaminants for which drinking water standards had not been
established, EPA selected proposed federal drinking water standards or Health Based Guidance Levels
developed by Arizona Department of Health Services. Groundwater cleanup standards established in the
Record of Decision are summarized in Table 3.
Table 3. Record of Decision Groundwater Cleanup Standards.
Compound
Cleanup Standards (p,g/L)
Basis for Cleanup Level
Benzene
5
Federal MCL
Dichlorodifluoromethane (Freon 12)
1,400
State Health-Based Guidance
Level
1,1 -Dichloroethene
7
Federal MCL
1,1 -Dichloroethane
No cleanup standard selected
N/A
1,1,1 -T richloroethane
200
Federal MCL
1,2-Dichloroethane
5
Federal MCL
1,2-Dichloroethene (cis)
70
Federal MCL
1,2-Dichloroethene (trans)
100
Federal MCL
1,2-Dichloropropane
5
Federal MCL
Acetone
700
State Health-Based Guidance
Level
Chlorobenzene
100
Federal MCL
Trichlorofluoromethane (Freon 11)
2,100
State Health-Based Guidance
Level
Trichlorotrifluoroethane (Freon 113)
210,000
State Health-Based Guidance
Level
Methyl ethyl ketone (2-butanone)
170
State Health-Based Guidance
Level
Dichloromethane (methylene chloride)
5
Proposed Federal MCL
Tetrachloroethene
5
Federal MCL
Toluene
1,000
Federal MCL
Trihalomethanes (total)
100*
Federal MCL
Trichloroethene
5
Federal MCL
Chromium (total)
50
Federal MCL
Xylenes (total)
10,000
Federal MCL
Vinyl chloride
2
Federal MCL
*The current federal MCL for total trihalomethanes is 80 jug/L; N/A - no standard available; jug/L = micrograms per
liter MCL = National Primary Drinking Water Standard expressed as the Maximum Contaminant Limit
For soil vapor cleanup standards, EPA required that soil vapor performance standards be established
using site-specific modeling. Soil vapor performance standards were established in a 1996 Soil Vapor
Performance Verification Plan. EPA revised the soil vapor performance standards in its 2009 Explanation
of Significant Difference #1 and again in its 2016 Explanation of Significant Difference #2.
In December 2009, EPA signed an Explanation of Significant Difference # 1 to update the soil vapor
remedy and the soil vapor performance standards. In the Explanation of Significant Difference #1, EPA
modified the soil vapor treatment technology for the soil vapor extraction and treatment system from
thermal oxidation to a proprietary cryogenic treatment system. As described in the Explanation of
Significant Difference #1, EPA allowed carbon treatment to be used if determined feasible and revised the
soil vapor performance standards that were based on equilibrium soil vapor concentrations to result in
corresponding soil screening levels.
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
9
-------
In May 2016, EPA issued an Explanation of Significant Difference #2 which established new soil vapor
performance standards based on the Soil Vapor Extraction Endstate Tool modeling to calculate
performance standards which would be protective of groundwater (Table 4). As described in the
Explanation of Significant Difference #2, EPA established the remedial action objectives for the Site
which are consistent with the intent of the 1992 Record of Decision.
EPA did not expressly identify remedial action objectives in the Record of Decision; however, EPA
clarified in the 2016 Explanation of Significant Difference #2, that the remedial action objectives for the
Site are the following:
Groundwater remedial action objectives
• Prevent human exposure to groundwater contaminated by Site contaminants above maximum
contaminant levels and, for contaminants that have no maximum contaminant levels, above
Health-Based Guidance Levels established by Arizona.
• Restore groundwater throughout the Site to concentrations at or below the maximum contaminant
levels and Health-Based Guidance Levels for Site contaminants.
Soils/Soil Vapor remedial action objectives
• Prevent human ingestion of or contact with soil or waste contaminated with Site contaminants
that represents an unacceptable exposure.
• Prevent leaching or vapor transport of Site contaminants from soil and waste in the vadose zone
to groundwater by attaining and maintaining soil vapor concentrations below soil vapor
performance standards that are protective of groundwater quality and will not result in
degradation of groundwater at concentrations above groundwater cleanup values at the Site
boundary.
10
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Table 4. Soil Vapor Performance Standards from the Explanation of Significant Difference #2.
Volatile Organic Compound
Soil Vapor Performance Standards
(ug/L)
Acetone
10
Benzene
14
2-Butanone (MEK)
4
Chlorobenzene
287
Dichlorodifluoromethane (Freon 12)
184,658
1,1 -Dichloroethene
148
1,2-Dichloroethane
4
1,2-Dichloropropane
10
Cis- 1,2-Dichloroethene
184
Trans- 1,2-Dichloroethene
5
Dichloromethane (methylene chloride)
10
T etrachloroethene
117
1,1,1 -Trichloroethane
3,070
Toluene
3,873
Trichloroethene
38
Trichlorofluoromethane (Freon 11)
188,370
Trichlorotrifluoroethane (Freon 113)
3,289,020
Xylenes
43,476
Vinyl Chloride
90
fig/L = micrograms per liter
2.3. Remedy Implementation
The Hassayampa Steering Committee implemented the remedy pursuant to the Administrative Consent
Order (EPA, 1988), the EPA 1992 Record of Decision, the Administrative Order (EPA, 1993), the
Consent Decree, the EPA 2009 Explanation of Significant Difference #1, and the EPA 2016 Explanation
of Significant Difference #2.
In 1994, the Hassayampa Steering Committee (composed of the companies responsible for implementing
the remedy) completed construction of the Site Remedy including: a groundwater extraction and
treatment system that includes a building with an air stripper treatment unit, four extraction wells and one
injection well; 29 monitoring wells to monitor the effectiveness of the treatment system; a multi-layer
membrane and soil cap meeting the requirements of Subtitle C of the Resource Conservation and
Recovery Act to prevent erosion and infiltration of contaminants into the groundwater; and a 6-foot-high
two-inch mesh chain link fence with locking gates and barbed wire to encompass the perimeter of the Site
to restrict access, with signs identifying the Site as a hazardous waste site every 100-feet. Additionally, an
environmental covenant between Maricopa County and the Arizona Department of Environmental
Quality was executed that requires all future use of the property to remain as a landfill pursuant to
Arizona Revised Statutes (A.R.S.) 49-771. The environmental covenant restricts all excavation, grading,
drilling, or mining at the Site except as approved by the Arizona Department of Environmental Quality.
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
11
-------
In 1996, the initial soil vapor extraction and treatment system was constructed. The system consisted of a
catalytic oxidation technology (also known as a regenerative thermal oxidation system) for treatment of
the soil vapor from 22 soil vapor monitoring/extraction wells. This system was shut down in 1999 and
replaced in 2006 with another system which was further modified in 2016. Details regarding the system
changes are discussed in Section 2.4.
2.4. System Operations/Operation and Maintenance, and Optimization
Operation and maintenance activities, monitoring, and investigations at the Site are conducted in
accordance with the 2017 Performance Monitoring and Verification Plan for Soil Vapor and Groundwater
and the Consolidated Operations and Maintenance Manual for the Hassayampa Landfill Superfund Site
and prior versions as applicable.
Groundwater Remediation System
The groundwater remediation system consists of four Unit A extraction wells EW-01UA through EW-
04UA; an air stripper and associated piping, pumps, and controls; one Unit B injection well (IW-01UB);
20 Unit A groundwater monitor wells, including wells MW-01UA through MW-14UA and MW-16UA
through MW-21UAR, and nine Unit B groundwater monitor wells, including wells MW-01UB through
MW-04UB, MW-06UB, MW-09UB, MW-10UB, MW-15UB, and MW-21UB (Figure 4).
Site inspections are performed monthly (by Geosyntec and Hargis+Associates on behalf of the
Hassayampa Steering Committee), to verify all systems are in working order and to perform any needed
preventative maintenance. Influent sampling is conducted annually, and effluent sampling is conducted
monthly after treatment in the air stripper. Total discharge of volatile organic compounds to the
atmosphere is calculated to ensure compliance with emissions criteria by determining the total mass
removed by the air stripper based on the groundwater influent and effluent concentration data. Operating
extraction wells are sampled quarterly, and non-operating extraction wells are sampled annually. Annual
maintenance is also conducted on the system, including dismantling the air stripper, manual scraping and
cleaning during disassembly, an acid bath, rinsing, and reassembly. Most monitoring wells are sampled
on a quarterly basis and a few are sampled semi-annually or annually. The sampling schedule is modified
as needed depending on the location of the wells and the results.
Soil Vapor Extraction System
The Hassayampa Steering Committee operated the first soil vapor extraction system intermittently
between 1996 to September 1998. In March 1999, the thermal oxidation treatment system was shut down
after it failed several compliance tests for destruction efficiency (contaminant destruction) the previous
year. Approximately 3,700 pounds of volatile organic compound contaminants were removed from the
subsurface soils between 1996 and 1998.
Data collected in 2005 indicated the need for further soil vapor extraction treatment at the Site after the
system had been shut off for 7 years. The Hassayampa Steering Committee began an investigation to
further characterize the migration of subsurface soil vapors at the Site and in 2006, the Hassayampa
12
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Steering Committee installed a replacement soil vapor extraction system with a proprietary cryogenic
technology and carbon treatment to remove the volatile organic compound contaminant vapors from the
system. During a subsequent 2007 investigation, significant upward trends in the concentrations of the
volatile organic compounds in the vadose zone soil vapor plume were detected. There was unexpected
contamination of groundwater in an up-gradient groundwater monitoring well (MW-11UA) due to vapor
migration. Therefore, additional soil vapor monitoring wells were installed, and 3 groundwater wells were
temporarily converted to soil vapor extraction wells. In 2011 these groundwater wells were returned to
use as soil vapor/groundwater monitoring wells.
In 2015, the Hassayampa Steering Committee conducted a pilot test to evaluate the feasibility of changing
to vapor-phase granulated activated carbon to treat the soil vapor, rather than the cryogenic treatment
system. The results of the pilot test indicated that switching to carbon treatment would be more cost
effective than continuing to operate the cryogenic system. In January 2016, the Hassayampa Steering
Committee dismantled the cryogenic treatment system, and installed a full-scale vapor phase granular
activated carbon soil vapor extraction treatment system in May 2016 and began its operation in August
2016. The Performance Monitoring and Verification Plan for the new system was submitted on March 21,
2017 and approved by EPA on March 24, 2017. A Consolidated Operations and Maintenance Manual was
completed in August 2017.
Currently, the soil vapor extraction system is periodically turned off to determine if cleanup levels have
been met based on the selected criteria (rebound tests). If the criteria are not met, the system is re-started.
See Section 3.1 Work Completed at the Site During this Five-Year Review Period for more information.
Flow rates from individual extraction wells are evaluated approximately weekly as a part of operation and
maintenance activities by collecting measurements of Pitot tube differential pressures and applied well
head vacuums. Volatile organic compound concentrations of the extracted vapors are evaluated at each
extraction well. Annual and semiannual soil vapor monitoring are conducted in October and April,
respectively. The 2,000-pound vapor granular activated carbon vessels are replaced as needed as
determined by the sampling results, typically occuring on an annual basis. Condensate is removed and
sent off-site as needed. Influent and effluent samples are collected monthly from the soil vapor extraction
system during operation. System emissions calculations are performed if any month shows a removal
efficiency below the target of 90%. The system will be shut down if volatile organic compounds and
hazardous air pollutants are above 9 lbs/day and 6 lbs/day respectively, or if system exhaust exceeds 100
parts per million by volume.
Soil Cap
The monitoring program for the cap includes inspection of the cap monthly, annually, and following
severe rainstorm events. Repairs are performed as needed based on the inspections.
Deed and Access Restrictions
The covenant restricting land use to a landfill remains recorded with the County and does not require any
monitoring. The site security fence is inspected and repaired if necessary.
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
13
-------
3. Previous Five-Year Review Protectiveness Statement
and Issues
The protectiveness statement from the 2016 Five-Year Review for the Hassayampa Landfill Superfund
Site stated the following:
The remedy at the Site is protective of human health and the environment. Concentrations of Contaminant
of Potential Concerns (COPCs) are decreasing, but the groundwater cleanup standards and the 2016
SVPS have not yet been achieved. Currently, there are no environmental exposure pathways that result in
unacceptable risks. The SVE system is successfully preventing vapor transport of COPCs from the vadose
zone to groundwater and the groundwater remediation system is preventing further migration of COPCs
in groundwater. Engineering and institutional controls prevent unacceptable exposure to COPCs in soil
and groundwater.
The 2016 Five-Year Review did not identify any issues or recommendations.
3.1. Work Completed at the Site During this Five-Year Review Period
Site inspection and maintenance occurred monthly. Personnel were not on-Site daily, however, alarms
were triggered if system failures occur as operations are automated and with sensors with preprogramed
shutdown thresholds. Occasional power outages have occurred on the Site resulting in system shutdowns
due to weather and scheduled maintenance. The contractors have been responsive to shutdowns and have
restarted the system and communicated issues to the EPA and ADEQ in a timely manner.
Over the last 5 years, the Hassayampa Steering Committee contractors have met approximately semi-
annually which typically include site visits by project managers to evaluate site and system conditions.
Semi-annual meetings with EPA and ADEQ personnel and contractors have been held to provide updates
of on-going work at the Site, review plans for upcoming work and to review and discuss the results of
sampling events.
Groundwater Remediation System
The groundwater remediation system operated approximately 98% of the time during this five-year
review period and was offline during power outages, low airflow alarms, maintenance for routine
mechanical issues, such as pump failures, or annual maintenance. These issues are accounted for in
annual planning and there are strategies in place to address them quickly and minimize downtime in the
event they occur. Even though the system has been performing well overall, it is aging, and increased
maintenance issues are expected in the future. The remaining life span of the system and its components
should be evaluated to ensure minimal downtime will continue.
During this reporting period, only extraction wells EW-03UA and EW-04UA were in operation.
Extraction wells EW-01UA and EW-02UA are have been in stand-by mode since mid-2010 as the wells
are not needed to maintain capture of affected groundwater. Water samples from the monitoring wells
14
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
(typically 2 biennially, 14 annually, 9 semiannually, 5 quarterly, 2 non-operating extraction wells
annually), 2 operating extraction wells quarterly, and quarterly air stripper influent and monthly effluent
were collected.
Approximately 3.4 gallons per minute are pulled by the two extraction wells for treatment. The volume of
groundwater (in gallons) that was pumped and treated was approximately 1.8 million, 1.7 million, 1.5
million, 1.6 million and 1.8 million in 2016, 2017, 2018, 2019, and 2020, respectively. Approximately
400 pounds of volatile organic compound chemicals were removed from the groundwater Unit A from
1994 through 2020 (3 pounds in 2020). Groundwater remediation system performance monitoring results
are further discussed in the Data Review Section 4.2.1 Groundwater.
The system water effluent samples have all be non-detect over the last five years except for acetone in
2016, which was not a confirmed result. On average, volatile organic carbon mass in the air stripper
emissions were 0.012 lb/day in 2016, 0.010 lb/day in 2017, 0.007 lb/day in 2018, 0.006 in 2019, and
0.008 lb/day in 2020.
Soil Vapor Extraction System
Several planned shutdowns and restarts for the soil vapor extraction system for rebound testing occurred
during the Five-Year Review period. The soil vapor extraction system first shut down on September 11,
2017 to begin the initial rebound testing program, and following three months of rebound testing, the
Vapor-phase Granular Activated Carbon soil vapor extraction system was restarted on January 15, 2018.
The system was shut down on July 9, 2018, and after three months the system was restarted on November
20, 2018. A third round of rebound testing began on July 8, 2019, and after nine months, the Vapor-phase
Granular Activated Carbon soil vapor extraction system was restarted on June 2, 2020. The system has
remained operational through the remainder of the 2020 reporting period. The Hassayampa Steering
Committee performed soil vapor monitoring during 2020 which included: sampling of selected Fine-
Grained Zone and sub-basalt vapor monitoring wells for fixed laboratory analysis of volatile organic
compound chemicals as part of the combined semiannual and 9-month soil vapor extraction rebound
testing sampling events in April 2020; and sampling of select Course-Grained Zone, Fine-Grained Zone
and sub-basalt vapor monitor wells for fixed laboratory analysis of volatile organic compound chemicals
as part of the annual sampling event in October 2020.
The 2,000-pound vapor granular activated carbon vessels were replaced with new carbon in 2016, 2017,
2018, 2019, and 2020. The spent carbon was shipped off-site for disposal. Condensate that collected in
the condensate storage vessel was not removed from the Site in 2020 but was removed and shipped off-
site for disposal in 2016, 2017, 2018, and 2019. The spent carbon and condensate wastes were profiled
and sent to a hazardous waste facility if required. Influent and effluent samples were collected monthly
from January through July in 2017, 2018, and 2019 and June through December 2020 from the soil vapor
extraction system.
The total mass volatile organic compound chemicals removed from the vadose zone during the reporting
period was 3,275 pounds, 813 pounds, 588 pounds, 345 pounds, and 540 pounds in 2016, 2017, 2020,
2018, 2019, and 2020, respectively. Since soil vapor extraction activities were resumed in March 2006, a
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
15
-------
total of approximately 223,880 pounds (over 111 tons) of volatile organic compound chemicals have been
recovered. Soil vapor extraction system monthly removal efficiencies were calculated to be between
47.98-99.99+% in 2016, 62-99+% in 2017, 29-99.9+% in 2018, 2-99.9+% in 2019, and 80-99.9+% in
2020. System emissions calculations of were performed when removal efficiency was below 90%.
Emissions were all well below the emissions requirements of 9 lbs/day for volatile organic compounds
(maximum of 1.61 lbs/day in December 2018) and 6 lbs/day for hazardous air pollutants, except for
December 2018 at 12.48 lbs/day of hazardous air pollutants. In October 2020 there was a slight
exceedance of the shutdown criteria of 100 parts per million by volume in the exhaust, so the system was
shut down until the carbon was replaced. The calculated emissions for that month were determined to be
0.38 lbs/day of volatile organic compounds and 0.54 lbs/day hazardous air pollutants.
Soil Cap
Routine inspections of the cap were performed according to the maintenance requirements to ensure the
integrity of the cap such as to identify potential damage by erosion and monitor rodent control measures.
Minor recurring erosion issues were identified near the main gate of the Site in 2020. As in the past, this
issue has been addressed in a reasonable timeframe by the County who assists the Hassayampa Steering
Committee with minor repairs. These areas of recurring erosion are related to runoff from the adjacent
closed municipal solid waste landfill area during major rain events and efforts to find a permanent
solution are ongoing. Pest control was conducted monthly for the Site, and additional measures were
taken if needed to address periodic rodent activity.
Deed and Access Restrictions
The land use restriction remains in place and no land use changes have been observed. No issues have
been reported regarding the site security fence.
4. Five-Year Review Process
4.1. Community Notification and Site Interviews
4.1.1. Five-Year Review Public Notice
EPA issued a public notice in the West Valley View, on March 10, 2021, stating that EPA was conducting
a Five-Year Review and inviting the public to submit any comments to the EPA (Appendix F). No
comments were received. The results of the review and the report will be made available at
http://www.epa.gov/superfund/hassavampalandfill and the following Site information repositories:
Arizona Department of Environmental Quality EPA Superfund Records Center
1110W. Washington Street 75 Hawthorne Street
Phoenix, Arizona 85007 Room 3110
(602) 771-4380 San Francisco, California, 94105
http://azdea.gov/records-center (415) 947-8000
16
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
4.1.2. Site Interviews
During the Five-Year Review process, interviews were conducted to document any perceived problems or
successes with the remedy that has been implemented to date (Appendix G). The results of these
interviews with the Hassayampa Steering Committee Project Manager, the Hassayampa Steering
Committee consultant Geosyntec (Principal Engineer and Project Manager), the Hassayampa Steering
Committee Project Manager, the Hassayampa Steering Committee consultant Hargis and Associates
Senior Hydrogeologist, U.S. Army Corps of Engineers Geologists, Maricopa County Risk Control and
Loss Prevention Manager, CALIBRE Systems, Inc a consultant to the Arizona Department of
Environmental Quality, the Project Manager, former Project Manager, and Unit Manager for the Arizona
Department of Environmental Quality are summarized below.
All interviewees felt that the project is progressing as expected and that communication among all parties
is ongoing and beneficial. They indicated that the groundwater and vapor plumes are contained and
decreasing in size while removing volatile organic compounds from groundwater and soil vapor.
The Senior Hydrogeologist at Hargis+Associates stated "Off-Site, down-gradient migration of Site-
related constituents has been prevented, the vertical migration potential of contaminants in groundwater is
low, and the remedy at the Site has been operated and maintained in a manner that has been and remains
protective of human health and the environment. The soil vapor system has been successful in decreasing
soil vapor concentrations to below the Soil Vapor Performance Standards during operation and has been
undergoing a series of rebound tests to evaluate how much longer it will continue to be needed.
Groundwater concentrations are decreasing in all wells except those located between the source area (Pit
1) and the extraction wells." Hargis performs monthly Site inspections and operation and maintenance on
Site components per the schedule approved in the operation and maintenance manual. Monthly
inspections include cap condition, security, well conditions, groundwater recovery system
operation/condition, etc. Hargis completes more thorough inspections annually, including teardown and
cleaning of the groundwater recovery system and they conduct groundwater sampling.
The Principal Engineer and the Project Manager with Geosyntec stated the following "Groundwater and
soil vapor conditions are frequently monitored to demonstrate contaminant containment and steady
progress towards remedial goals. Through operation of the soil vapor extraction system, soil vapor data
have exhibited significant declines, where the magnitude and extent of volatile organic compounds in soil
vapor have been dramatically reduced in comparison to conditions in 2006 when soil vapor extraction
system was restarted. Per the Agency approved Performance Monitoring and Verification Plan, soil vapor
volatile organic compounds concentrations in the Pit 1 source area have been reduced to levels that
support rebound testing and possible shutdown. Reductions in soil vapor volatile organic compounds
concentrations have resulted in commensurate declines in influent volatile organic compounds
concentrations to groundwater remediation system. These data trends continue to support the Conceptual
Site Model for the Site that was jointly prepared with the Agencies."
According to the Arizona Department of Environmental Quality (ADEQ) current and former Project
Managers and current Unit Manager, monitoring data indicates that impacts to groundwater are limited to
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
17
-------
a few on-Site wells and vapor concentrations are below the soil vapor performance standards. The SVE
system was shut down for rebound testing on several occasions. The system was restarted a few months
later after sampling indicated an increase of chemical concentrations (for several contaminants) over the
performance standards. The age of the groundwater system has resulted in increased equipment
malfunctions causing system shutdowns. They also stated that "Within the next 5 years Groundwater
Remediation System equipment nearing end of life should be replaced..." This was further echoed by the
Unit Manager who stated that the age of the system does have the potential to increase maintenance costs
as made evident by the reported equipment failures and malfunctions. They noted that countermeasures
should be discussed to reduce the frequency of power outages, especially during the summer monsoon
season.
4.2. Data Review
4.2.1. Groundwater
Groundwater contamination at the Site is primarily located near Pit 1 (Figure 2) and decreases in
concentration moving away from Pit 1. The aquifer has two units, the shallower Unit A and a deeper Unit
B. The contamination is located in Unit A. Comparison of water level elevations from paired wells
completed in Units A and B indicated that water level elevations in Unit A monitor wells are, on average,
about 18 feet higher than water level elevations in monitor wells completed in Unit B. These data suggest
that a downward vertical gradient exists between these two units. However, based on data collected to
date, while there is evidence that some migration of contaminants has occurred from Unit A to Unit B
such as intermittent detections of 1,1-dichloroethane (1,1-DCA) in MW-01UB, it is not occurring at
concentrations above the groundwater performance standards. While the gradient between aquifer Unit A
and Unit B is downward, the pump and treat system reduces the vertical gradient reducing the potential
for vertical migration between the aquifer units. The pump and treat system located in Unit A is primarily
used for containment and to depress the water table beneath Pit 1. If the pump and treat system was turned
off, the groundwater levels would increase and saturate contaminated soil and mobilize contaminants into
the groundwater. Appendix C includes a summary of the groundwater exceedances during the reporting
period and results of the Mann-Kendall analysis.
4.2.1.1 Hydraulic Capture
Containment of groundwater contamination was determined by groundwater gradients, down gradient
wells with no detections and results of a recovery test. Groundwater in the A Unit flows to the southeast
across the Site except near the extraction wells where groundwater flows towards the extraction wells.
The wells with concentrations exceeding cleanup levels are within the capture zone and down gradient
wells have been non-detect during the reporting period (Figure 5). An aquifer recovery test was conducted
in 2019 to evaluate contaminant migration with the pump and treat system off. The recovery test was
planned for one year; however, the extraction wells were turned back on after one month due to
groundwater flow direction near MW-12UA shifting from southwest to a more southeasterly flow which
had the potential to allow contamination to migrate off site. The groundwater gradient during pumping
compared to the results of the recovery test confirmed the pump and treat system is creating hydraulic
capture.
18
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Two monitoring wells (MW-6UA and MW-19UA) located between Pit 1 and the extraction wells had
increasing trends during this five-year review period. The greatest increase in concentration was at MW-
06UA which had 1,1-DCE increase from 1.700 ug/'L in April 2015 to 4,340 ug/L in July 2020. The
reason for the increasing tends is not completely understood however it may be caused by groundwater
contamination migrating from Pit 1 towards the extraction wells. The wells with increasing trends are
within the capture zone so the contamination is expected to be removed by the pump and treat system.
The plume migration will continue to be monitored to ensure it does not migrate past the extraction wells.
Source: Third Five-Year Review Report for the Hassayampa Landfill Superfund Site, Figure 2, EPA, 2011.
Figure 4 Monitoring and Extraction Well Locations
4.2.1.2 Groundwater Restoration
Restoring groundwater to beneficial use is not likely to occur in a reasonable time frame based on the
high concentrations of contaminants in groundwater (129,000 (ig/L of 1,1-DCE at MW-19UA) and the
slow removal rate (approximately 3.4 pounds per year) of contaminants by the pump and treat system
(Figure 6). The mass of contaminants removed from groundwater by the groundwater remediation system
is calculated as the product of influent volume and average total concentrations of contaminants. The
contaminant mass removal rate from groundwater has reached asymptotic levels (Figure 6) so the pump
treat system is doing little to restore the aquifer to beneficial use.
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
19
-------
The primary source of contamination in groundwater was vapor phase contaminants leaching into
groundwater. The soil vapor extraction system is now removing the vapor phase as a source of
contamination, however high concentrations of contaminants in the groundwater will remain. The
estimated time to cleanup groundwater is between several decades to greater than 100 years. US ACE
estimated the cleanup time using the extraction rate of the pump and treat system, the estimated pore
volume of the area of influence of the pump and treat systems and the number of pore volumes that need
to be pumped out to reduce the concentration of 1,1-DCE from 129,000 to 7 pg/L.
Groundwater contaminant mass would need to be removed at a higher rate than the current pump and
treat system to achieve cleanup in a reasonable time frame. When it is determined that the soil vapor
extraction system has met the soil vapor performance standards then treatment of groundwater in the
source area should be evaluated to decrease the time to cleanup. The second Five-Year Review included a
source area analysis that provided potential methods for optimizing treatment m the source area.
, 11DCE=5300
12DCP=31.3
5TCE=170
"*PCE=48
~11DCE=12900
12DCA=11
12DCP=973
TCE=804
"PCE=203
>11DCE=4340
'l20CP=25
"*rCE=120
PCE=30
.MW-19UA MW-06UA
Special
PitA^€
11DCE=70MW-16UA
12DCP=43 ®
TCE=130
PCE=22 .
_EW-04UA
11DCE=360
_12DCP=12
frCE=55 '
PCE=11
MW-12UA
MW-04UA
IW-07UA
'11DCE=711
TC£=51
PCE=7.8
Special
Pit Area;
MW-20UA
11DCE=31
.TCE-28
'11DCE=4101
TCE=120 -
PCE=9.3
MW-14UA
/ » ¦
11DCE=27.
Special
Pit Area
1979
MW-21UAR
EW-03UA
11DCE=25.
TCE=15
MW-01UA
V®
11DCE=32_
TCE=8
Special
Pits
"Area
maximum concentration during previous five years (ug/L)
Abbrev Chemical Cleanup Level (ug/L)
11DCE 1,1-Dichlororethene 7
12DCA 1,2-Dichloroethane 5
12DCP 1,2-Dichloropropane 5
PCE Tetrachloroethene 5
TCE Trichloroethene 5
® Wells with exceedances during the previous five years
® Down gradient wells with no detections during previous five years
XXX Water elevations from October 2020 (ft amsl)
MW-03UA
\ MW-02UA
Source: Adapted by US ACE from Figure 7 of the 2020 Annual Groundwater Monitoring Report, Hargis + Associates, Inc., 2021.
Figure 5. Maximum Groundwater Exceedances from 2015 through 2020 (units in ug/L)
20
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
at
*
•
t
•
*
m
*9
«»
¦' •
•
•
/
\
•
•
\
f
/
t
Intermittent
Ol
SVE
jerat
on
.
•
i •
«
\
*.
.Jr
SVE Restart
March 2006
• ,
•4
*
*7
V
mm
1694 1996 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2016 2019 2020 2021
13 2014 2015 2016 2017 2018 2019 2020 2021
£
C/>
O
>
&
3
<
450
400
350
300
250
200
150
100
50
0
1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 20
Source: Figure 12 from the 2020 Annual Monitoring Report, Hargis + Associates, Inc., 2021.
Figure 6. Groundwater Pump and Treat Mass Removal
4.2.2. Soil Vapor
Soil vapor at the Site is a source of contamination for groundwater and the removal of the soil vapors has
decreased volatile organic compound concentrations in groundwater. Since 2006, the soil vapor extraction
system (Figure 7) (11 fine-grained zone extraction wells, 1 coarse-grained zone extraction well, 2 dual
completion wells) has removed over 200,000 pounds of volatile organic compounds (Figure 8). Soil
vapor performance standards (Table 4) were developed to determine the concentration of soil vapor that
would not cause groundwater concentrations to exceed cleanup levels. The soil vapor performance
standards are compared to the arithmetic mean of the concentrations from eight wells near Pit 1 (Table 5).
During the reporting period the most soil vapor performance standards exceedances were for 1,2-
Dichloroporpane which exceeded the soil vapor performance standards six out of the fifteen times it was
sampled for during the reporting period. All soil vapor performance standards exceedances, since 2017,
have occurred when the soil vapor extraction system has been off for rebound tests. Three rebound tests
have been completed for the soil vapor extraction system during the reporting period. The first two
rebound tests completed in 2017 and 2018 lasted three months and the soil vapor performance standards
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
21
-------
were exceeded at the end of the three months. The third rebound test in 2019 lasted nine months and soil
vapor performance standards were not exceeded until the end of the test at nine months. Based on the
decrease in concentrations at the soil vapor monitoring wells and the longer timeframes for the soil vapor
concentrations to exceed standards during shutdown periods, the soil vapor extraction system is close to
meeting the soil vapor performance standards.
Source: Figure 3 from the 2020 Annual Monitoring Report, Geosyntec consultants, 2021.
Figure 7 Location of Soil Vapor Extraction Wells
22
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Source: Figure 14 from the 2020 Annual Monitoring Report, Hargis + Associates, Inc., 2021.
Figure 8. Soil Vapor Extraction (SVE) System Mass Removal
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
23
-------
Table 5. Soil Vapor Exceedance During the Reporting Period
1,2-DCP
DMK
MC
MEK
TCE
SVPS
10
10
10
4
38
4/15/2015
19.6
21.4
9.9
9.9
43.7
10/14/2015
16.4
50.9
9.4
8.6
37.3
4/13/2016
10.9
21.9
4.8
3.7
21.8
10/12/2016
7.7
13.0
4.9
1.4
11.5
4/11/2017
8.5
8.5
5.0
1.3
17.1
10/11/2017
9.5
9.0
3.9
3.2
16.8
12/12/2017
14.0
3.4
8.1
1.3
20.4
4/23/2018
5.8
4.8
2.3
1.1
11.4
8/9/2018
5.9
6.1
2.6
0.3
8.3
10/9/2018
10.5
4.6
5.5
0.6
21.0
4/17/2019
2.9
2.6
1.0
0.1
3.5
8/8/2019
7.6
2.9
2.8
0.4
12.0
10/8/2019
9.1
2.1
5.7
0.3
17.5
4/14/2020
10.5
2.6
12.4
0.3
12.8
10/14/2020
2.7
3.9
2.5
0.3
5.9
Arithmetic mean of concentrations from eight wells near Pit 1
Wells used: MW-18UA, MW-19UA, P-01-FINE. V-11-FINE. VE-01-FINE. VE-01-SB.
VE-02-FINE. VE-02-SB
Higliliglited cells are SVPS exceedances
SVPS= Soil Vapor Performance Standards
12DCP= 1,2-Dichloropropane
DMK= Acetone
MC= Methylene Chloride
MEK= Methylethylketone
TCE= Trichloroethene
4.3. Site Inspection
On October 20th and 21st, 2020, Matthew Masten, USACE, conducted a site inspection on behalf of EPA
to oversee the annual groundwater treatment system maintenance. Hassayampa Steering Committee
contractors Jeffery Menken, Michael Hall and Daniel Hall of Hargis+ Associates were also in attendance.
The visit included contractor visual observation of overall site conditions, update on the current status of
the remedy, and inspection of the disassembly and cleaning of the air stripper system. The trays, chutes,
and pans from the air stripper were removed for cleaning and inspected for pitting and leaks. No
remarkable damage was noted. Once all the scale was removed, the air stripper was reassembled. The
system appeared to be in good functional shape, with no leaks.
On July 13, 2021, Mr. Masten conducted the Five-Year Review Site inspection on behalf of EPA. Natalie
Romanoff, the Arizona Department of Environmental Quality Project Manager and Hassayampa Steering
Committee contractors were also in attendance. They visually inspected the landfill site. No erosion
problems were noted near the gate or on the cap. The site appeared to be in good shape overall. The
vegetation was notably well maintained and mowed down compared to the previous year. Lack of
monsoon moisture in the summer likely played a factor.
24
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
5. Technical Assessment
5.1. Question A: Is the remedy functioning as intended by the decision
documents?
Yes, the remedy is functioning as intended as the groundwater remediation system, soil vapor extraction
system, landfill cap, and institutional controls are functioning according to the decision documents. In
addition, decreasing site contaminant trends and the effective capture and control of them are occurring.
The Hassayampa Steering Committee conducts quarterly, semi-annual, and annual monitoring; maintains
logs for the groundwater remediation system and soil vapor extraction treatment systems; and ensures
compliance with the Record of Decision.
The groundwater remediation system and the soil vapor extraction system are equipped with alarm
notifications systems and provide real-time notification if unexpected operational failure occurs such as
due to power outages. Systems are brought back online in a timely fashion and downtime has not
impacted the effectiveness of the remedial systems.
Groundwater Remediation System
The groundwater remediation system is functioning successfully to ensure volatile organic compound
contamination is being captured and controlled at and in the immediate vicinity of the Site. Capture of
contaminated groundwater in Unit A appears to be maintained by the extraction system. Concentrations
are decreasing except for wells MW-06UA and MW-19UA located between Pit 1 and the extraction
wells. The overall decreasing trends indicate the systems are functioning as intended, and the increases
between Pit 1 and extraction wells are likely do to contaminant migration from the source area towards
the extraction wells, which is a desired outcome of remediation. Additionally, Unit A groundwater is
being captured by the groundwater extraction wells limiting contaminant flows between Unit A and Unit
B, so vertical migration of contaminants in Unit A to Unit B groundwater does not appear to be occurring.
Unit B groundwater contaminant concentrations are below groundwater cleanup standards. Additionally,
emissions from the air stripper are all below regulatory standards.
However, the pump and treat system removes a relatively small amount of mass from the Site compared
to the vapor extraction system and has a minimal impact on the overall mass at the Site. The pump and
treat system will need to be operated indefinitely for several decades to over 100 years to cleanup
groundwater to beneficial use. The second Five-Year Review included a source area evaluation that
provided a brief evaluation of available methods for cleaning up groundwater in the source area.
Additional groundwater treatment in the source area should be re-evaluated after the soil vapor extraction
system meets the soil vapor performance standards in the vadose zone. This is anticipated to occur prior
to the next Five-Year Review. Additionally, various components of the pump and treatment will likely
require replacement as the system ages.
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
25
-------
Soil Vapor Extraction System
The soil vapor extraction system, which restarted in 2006, is functioning as intended. During soil vapor
extraction operation, only nine wells had concentrations that exceed the standards, and concentrations of
contaminants in the vadose zone are decreasing. The soil vapor volatile organic compound concentrations
are below the soil vapor performance standards in monitoring wells near the source area (Pit 1). 1,2-
Dichloropropane and Methylethylketone exceeded soil vapor standards in April 2020 but were below the
standards in October 2020. While the system has been shut down and re-started numerous times to assess
the rebound of contaminants, the soil vapor extraction system shutdown and restart cycles are a tool to
determine if the soil vapor concentrations will remain below the performance standards and not an
indication of remedy performance issues. There has been one shut down in October 2020 due to
exceedances in air emissions however, typically the emissions are well below standards. One other
instance of effluent above the hazardous air pollutants occurred in December 2018. These isolated
instances of emissions exceedances do not indicate a significant issue with remedial performance.
Soil Cap
The multilayer landfill cap has been effective in containing the waste and contaminants and prevents
human exposure to the contaminants at the Site. Any necessary repairs have been addressed within a
reasonable timeframe, and rodent control measures are on-going to ensure damage is prevented and/or
mitigated.
Deed and Access Restrictions
The 1994 covenant restricting use of the Site to a landfill remains in place, and Maricopa County
complies with its requirements. No Site security issues were identified during the reporting period, and
the Site fence is intact.
5.2. Question B: Are the exposure assumptions, Toxicity Data, Cleanup
Levels, and Remedial Action Objectives Used at the Time of Remedy
Selection Still Valid?
Yes, the exposure assumptions are still valid. Contamination has not migrated off-site to any nearby
production wells, and site access is restricted so potential exposure pathways are not complete. There
have been no revisions to applicable or relevant and appropriate requirements that affect the
protectiveness of the remedy at the Site (Appendix D). The contaminants that do not have Federal criteria
and only State Health Based criteria are evaluated in Appendix E (Toxicity Analysis). EPA's acceptable
toxicity risk ranges are still met by the remedial goals. EPA updates target cancer risk and target hazard
quotients (non-cancer risks) risks on a regular basis and changes noted in Appendix E do not affect
protectiveness. Given the current understanding that landfills have been a source of Per- and
polyfluoroalkyl substances (PFAS) contamination at other locations, the current sampling program should
include sampling and analysis for PFAS to ensure that the Hassayampa landfill is also not a source.
However, the current groundwater extraction system is currently controlling migration of the Site
contaminants, so there is no possible exposure if PFAS is detected.
26
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
5.3. Question C: Has Any Other Information Come to Light That Could
Call Into Question the Protectiveness of the Remedy?
No additional information has come to light that would affect the protectiveness of the remedy. The Site
is listed in the 2019 Government Accountability Office Superfund Climate Change report
(https://www.gao.gov/products/GAO-20-73) as an area which could potentially be impacted by other
flood hazards and is not in an area with direct flood susceptibility (GAO, 2019). The report utilizes the
Federal Emergency Management Agency's national flood hazard layer with data relevant as of 2018.
Should uncontrolled flooding occur, it may increase the contaminated groundwater concentrations as a
result of soil vapor contaminant movement. The report indicates that the Site is not in a wildfire hazard
zone.
6. Issues/Recommendations
There are no issues or recommendations identified in the Five-Year Review.
6.1. Other Findings
The following are recommendations to improve management of the operations and maintenance but do
not affect current and/or future protectiveness:
• Determine total mass of volatile organic compounds in groundwater and estimate an approximate
timeframe towards achieving restoration of aquifer to drinking water standards. Depending on the
estimated timeframe for groundwater restoration a treatment strategy for groundwater in the source
area should be re-evaluated for options to decrease the time to achieve cleanup standards.
Additionally, groundwater remediation system equipment is aging, and should be evaluated for
replacement in coordination with any optimization efforts.
• A permanent solution to the areas of recurring erosion from runoff from the adjacent closed municipal
solid waste landfill area during major rain events should be developed.
• Countermeasures should be identified to reduce the frequency of power outages, especially during the
summer monsoon season.
• The groundwater sampling plan should be modified to include Per- and polyfluoroalkyl substances to
determine if these constituents are present.
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
27
-------
7. Protectiveness Statement
Table 6. Protectiveness Statement
Sitewide Protectiveness Statement
Protectiveness Determination: Click here to enter a date
Protective
Protectiveness Statement:
The remedy at the Hassayampa Landfill Superfund Site is protective of human health and the enviromnent. The
groundwater remediation system is preventing further migration of Site contaminants in groundwater and the soil
vapor extraction system and soil cap is successfully preventing vapor transport of Site contaminants from the
vadose zone to groundwater. Engineering and institutional controls prevent unacceptable exposure to Site
contaminants in soil and groundwater.
8. Next Review
The next Five-Year Review report for the Hassayampa Landfill Superfund Site is required five years from
the completion date of this review.
28
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Appendix A: List of Documents Reviewed
Conestoga-Rovers Associates (CRA) and Errol L. Montgomery & Associates, Inc., (M&A), 1996.
Groundwater Performance Standards Verification Plan, Hassayampa Landfill, Maricopa County, Arizona.
Revised April 24
EPA. 1988. Administrative Consent Order, EPA Docket No. 88-08, Hassayampa Landfill. March 1.
EPA. 1992. Record of Decision, Hassayampa Landfill Superfund Site, Maricopa County, Arizona,
August 6
EPA. 1993. Administrative Order for Remedial Design Activities, EPA Docket No. 93-09, Hassayampa
Landfill Superfund Site. March 30
EPA. 1994. Consent Decree CIV 94-1821 PHX RCB. Filed November 28, 1994
EPA. 2009. Explanation of Significant Differences #1, Hassayampa Landfill Superfund Site, Maricopa
County, Arizona, December 23
EPA. 2016. Explanation of Significant Differences #2, Hassayampa Landfill Superfund Site, Maricopa
County, Arizona, May 17
EPA. 2016. Fourth Five-Year Review Report for Hassayampa Landfill Superfund Site Maricopa County,
Arizona, September 26
Geosyntec Consultants. 2016. Full-Scale Carbon Pilot Tests Summary Report and Soil Vapor Treatment
System Transition Plan, Hassayampa Superfund Site, Maricopa County, Arizona. June 10
Geosyntec and Hargis + Associates, Inc. 2017a. Performance Monitoring and Verification Plan for Soil
Vapor and Groundwater. Hassayampa Landfill Superfund Site. March 21
Geosyntec and Hargis + Associates, Inc. 2017b. Consolidated Operations and Maintenance Manual for
the Hassayampa Landfill Superfund Site. August 9
Geosyntec and Hargis + Associates, Inc. 2017c. 2016 Annual Monitoring Report, Hassayampa Landfill
EPA Superfund Site. January 31
Geosyntec and Hargis + Associates, Inc. 2020. 2019 Annual Monitoring Report, Hassayampa Landfill
EPA Superfund Site. January 31
Hargis + Associates. 2021. 2020 Annual Monitoring Report Hassayampa Landfill Superfund Site,
Maricopa County, Arizona. January
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
29
-------
Hargis + Associates, 2020. 2019 Annual Monitoring Report, Hassayampa Landfill Superfund Site,
Maricopa County, Arizona, January 31
Hargis + Associates. 2019. 2018 Annual Monitoring Report, Hassayampa Landfill Superfund Site,
Maricopa County, Arizona, January 31
Hargis + Associates. 2018. 2017 Annual Monitoring Report, Hassayampa Landfill Superfund Site,
Maricopa County, Arizona, January 31
Hargis + Associates. 2017. 2016 Annual Monitoring Report, Hassayampa Landfill Superfund Site,
Maricopa County, Arizona, January 31
Hargis + Associates. 2013. Site Conceptual Model (Contaminant Fate and Transport) for Hassayampa
Landfill Superfund Site, April 30
30
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Appendix B: Site Chronology
Event
Date
Hazardous Waste Disposal (liquids and solid waste in the 10-acre Hazardous Waste
Disposal Area of the Landfill)
April 20,1979 to October 28,
1980
Site listed on the National Priorities List by EPA
July 22, 1987
Administrative Consent Order No. 88-08 to conduct the Remedial Investigation/Feasibility
Study
February 19,1988
Remedial Investigation Report
April 4, 1991
Results from Vadose Zone Monitor Borings, Hazardous Waste Area
August 30, 1991
Feasibility Study Report
May 20, 1992
Record of Decision
August 6, 1992
Administrative Order No. 93-09 to design and implement remedy
March 30, 1993
Consent Decree No. CIV 94-1821 for remedy
November 28,1994
Groundwater Pilot Study
August 1993 to June 1995
Soil Cap Design and Construction
March 1994 to September
1995
Hydraulic Containment Evaluation Report, Established Groundwater Remediation System
June 1,1995
Soil Venting and Treatment System, Design and Construction
October 1995 to July 1996
Groundwater Remediation System began to operate
March 1996
Construction Completed
September 30,1997
Soil Venting and Treatment System Shutdown
September 6, 1998
First Five-Year Review Report
September 28,2001
Groundwater Remediation System, Revised Operation and Maintenance Manual
December 26, 2001
Addendum to First Five-Year Review Report
April 24, 2002
Treatment of Soil Vapor in Non-Capped Area (North), Passive Venting Pilot Test
February 2001 to July 2003
Passive Venting Pilot Test Postponement of Expanded System
July 18,2003
Re-evaluation of Site Conceptual Model, Additional Investigation
May 2004 to January 2006
Site Conceptual Model, Estimation of Pneumatic Properties Report
January 24,2006
Soil Vapor Extraction System redesign and start-up
March 2006
Second Five-Year Review Report
September 22,2006
Groundwater Remediation System, Proposed Site Pilot Test: 6-Month Shutdown of 2
Extraction Wells
June 3,2009
Summary of Soil Vapor Extraction Remedy Component
October 2, 2009
Explanation of Significant Difference # 1
December 23, 2009
Groundwater Remediation System, Optimization 6-Month Pilot Test Results and July
2010 Study
March 29, 2010
Third Five-Year Report
September 30,2011
EPA determined the Site is Ready for Reuse and Redevelopment
September 26,2012
Consolidated Operations and Maintenance Manual
April 4, 2013
Site Conceptual Model (Contaminant Fate and Transport)
April 30,2013
Explanation of Significant Differences #2
May 17, 2016
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
31
-------
Event
Date
Full-Scale Carbon Pilot Tests Summary Report and Soil Vapor Treatment System
Transition Plan
June 10, 2016
Fourth Five-Year Report
September 26, 2016
Performance Monitoring and Verification Plan for Soil Vapor and Groundwater.
Hassayampa Landfill Superfund Site
March 21, 2017
Consolidated Operations and Maintenance Manual for the Hassayampa Landfill Superfund
Site
August 9, 2017
Workplan to Perform One-Year Aquifer Recovery Testing
July 10,2019
32
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Appendix C: Data Review
This appendix provides a summary of the groundwater and soil vapor contamination detected at the Site
during the reporting period. Section 4.2 provides a description of how the data relates to the remedial
action objectives in the Record of Decision.
Groundwater
Groundwater contamination at the Site is primarily contained on Site within the Unit A (shallower)
aquifer. Table C-l provides a summary of the detections in groundwater during the reporting period and
Figure 4 shows the locations of the wells. During the reporting period, 12 wells had groundwater
contaminant exceedances. The most frequently detected chemical was 1,1-Dichloroethene which was
detected in 12 wells and had a maximum concentration of 129,000 (ig/L (cleanup level 7 j^ig/L) at MW-
19UA. Mann-Kendall trend analysis was completed using data from wells that exceeded cleanup levels
and had at least four detections during the reporting period. A summary of the Mann-Kendall results is
included in Table C-l and the figures with all of the results are included in this appendix. The only wells
with increasing contaminant trends during the reporting period were MW-06UA and MW-19UA. The
wells are the closest downgradient of Pit 1 and within the containment of the groundwater extraction
system. All of the other wells and the influent concentrations had declining or stable concentrations
during the reporting period indicating the Site contamination overall is decreasing.
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
33
-------
Table C-l. Summary of Groundwater Exceedance Between 2015 and 2020
Well
1,1-
Dichloroethene
1,2-Dichloroethane
1,2-Dichloropropane
Trichloroethene
Tetrachloroethene
Benzene
Cleanup
Standard
7
5
5
5
5
5
Max
(Hg/L)
Exc
MK
Max
(Hg/L)
Exc
MK
Max
(Hg/L)
Exc
MK
Max
(Hg/L)
Exc
MK
Max
(Hg/L)
Exc
MK
Max
(Hg/L)
Exc
MK
EW-02UA
7.5
1
S
EW-03UA
25
22
S
15
22
D
EW-04UA
360
24
D
12
13
D
55
24
D
11
6
D
MW-01UA
32
3
S
8
2
NT
MW-04UA
711
24
NT
51
23
S
7.8
17
NT
MW-06UA
4340
25
1
25
10
1
120
25
1
30
24
1
MW-07UA
31
6
NT
28
6
NT
MW-12UA
700
6
S
43
7
D
130
7
PD
22
7
PD
MW-14UA
27
6
D
MW-18UA
5300
25
D
31.3
21
S
170
25
D
48
23
D
MW-19UA
12900
25
1
11
12
D
973
25
PD
804
25
NT
203
25
1
8.3
11
NT
MW-20UA
410
12
D
120
12
D
9.3
9
D
INFLUENT
240
24
D
8.5
6
D
41
24
D
7.7
4
D
Exc= number of exceedances between 2015 and 2020
Max=maximum concentration between 2015 and 2020
|jg/L=micro grams per liter
MK=results of Mann-Kendall trend analysis
S=stable, D=decreasing, PD=probably decreasing, NT=no trend, l=increasing,
34
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Sampling Point ID:
EW-02UA
MW-01UA
MW-07UA
MW-11UA
MW-12UA
MW-14UA
MW-20UA
Sampling
Event
Date
11DCE CONCENTRATION (ugA.)
1
11 -Apr-1 c
US
410
2
12-Oct-1c
32
31
420
27
380
3
.--Ac-' :
400
4
5
5.6
IS
2.17
550
23
290
5
i -A;' ~
327
320
6
14-Oct-17
6.6
17
700
22
290
7
7-Aor-' £
2.S5
260
8
S-Gct-18
7.5
8.9
IS
430
16
250
9
13-Apr-19
210
10
13-Jul-10
6.4
11
6-Oct-19
5.3
7
19
1.58
230
16
230
12
11 -Apr-20
223
13
11 -Od-2Q
12.8
28.4
219
15.8
277
14
15
16
17
IS
1©
20
Coefficient of Variation:
0.16
0.79
0.28
0.31
0.40
0.24
0.23
Mann-Kendall Statistic <5):
-2
0
2
0
-7
-14
-47
Confidence Factor:
62.5%
40.8%
57.0%
40.8%
B€4%
99.6%
>93.9% M
Concentration T rend:
Stable
Stable
No Trend
Stable
Stable
Decreasing
Decreasing
tOQO
O)
3.
C
o
c
o
c
o
o
¦EW-C2UA
¦MVV-01 UA
¦ Wk'V-OTJA
• MW-11UA
»mvv-i2Ua
-MW-14W
"MW-2DLW.
12H4 0&16 09/17 Q2fW
Sampling Date
oem
1&21
Nates:
1. At feast four independent sampfeig events per well are required for calculating the trend. Methodology is valid for 4 to 40 samples,
2. Confidence in Trend = Confidence (in percent) th3t cwisdtuent concentration is increasing (S>0) or decreasing (S<0)c >05% = increasing or Decreasing;
a 90% = Probably Increasing or Probably Decreasing; < 90% and S>D = No Trend; < SO%. SsQ, and COV a 1 = No Trend: < 90% ana COV < 1 = Stable
MettKXicfesgy based on "MAROS: A Decision Support System fa* Optinrazing Monitoring Plans", J J. Aziz, M. Ling H.3. Rifai, C.J. Newel1, and J.R. Gonza&es,
Ground Warer, 41(3):355-367, 2003.
DISCLAIMER: The GSI Mann-KendaK TooM is avaSable 'as is*. Ccnsjderaijfe care .has been exercised in preparing ftes software product' hcwever, to party; (betiding wftrout
Irmtefiofi GSI Environmental inc.. makes any representation or tvarranty regarding the accuracy, c&rectness, or completeness of the information contained .heran, and no such
party stall be .Vaofe for any aired indirect consequential incidental or other damages resuimg from ffie use of the produ ct or me rnfomrafjon corrtaViea' herein. Information in
tins publication is sub,iect to cnange witrout notice. GS/ Enwro.nrrienSaf Inc., disc/aims any responsibly or obligation to update the information contained herein.
GSI Emmnmenta/ inc., www. g&Lner.com
Figure C-l. 1,1-DCE concentration trends from 7 of the 13 wells in the A-zone aquifer with exceedances
during the reporting period.
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
35
-------
GSI MANN-KENDALL TOOLKIT
for Constituent Trend Analysis
Evaluation Date
Facility Name:
Conducted By:
l-Mar-21
Hassyampa Landfill
Jeffrey Vfeiss
Job'ID:
Constituent
Concentration Units:
11DCE
uaL_
Sampling Point tD:| EW-03UA
EW-04UA
Inflnjent
MW-04UA
MW-06UA
MW18UA
I MW-19Ufl~~j
11DCE COWCENTEATIOW (uglLJ
1
1 C-Jar-us
11
320
22D
20C0
3603
693C
2
11-Apr-15
12
360
240
540
1700
4603
603D
3
11-J0-15
24
310
230
470
1900
5300
81OC
4
12-OCM5
25
223
17D
520
1900
¦3D03
6&X
5
9-J3P-15
25
203
140
510
21 CO
4403
8600
&
9-AET-16
15
193
14D
410
1900
3403
750D
7
9-Jli-16
2D
140
11D
390
1900
3403
sooo
ft
EMDct-16
2D
190
13D
503
251X3
3300
82X
&
14-Jar-'7
2D
170
11D
593
2800
3103
89X
10
B-Apf-17
13
150
96
510
23D0
3303
8600
11
15-JU-17
12
130
11D
510
27CO
3203
95X
12
14-Oct-17
14
193
96
593
9X0
3C03
9400
13
7-JarMB
1B
133
97
390
32 CO
3100
99X
14
7-Apr-IB
10
110
76
440
25CO
2503
89X
15
13-OuMB
10
110
73
440
3200
2603
9700
16
B-Oct-1B
90
92
4443
93CO
2603
93GC
17
12-J3P-19
99
57
£93
3800
2 £03
99X
IB
15-Apf-19
15
110
62
503
9300
2403
19
3-JU0-1 &
8100
20
13-Jii-15
IB
96
¦33
570
33CO
2303
9400
21
'2-Aug-15
23
65D
2C03
7400
22
6-Oct-19
14
120
72
393
*X0
2 £03
9XC
23
1i-Jar-20
19.7
133
87.2
£59
4260
3040
121 CO
24
I1-Apr-2C
12.3
121
71.8
711
40£0
2650
12X0
25
11-JU-2C
15
113
95.5
487
4-340
2293
685C1
25
11-Oct-2D
17.5
114
71.5
492
3770
2160
9150
27
2ft
29
30
Coefficient or Variation:
0_28
0.47
0.45
0.26
033
0-26
0.18 |
Mann-Kendall Statistic (&}:
-42
-177
-210
3
198
235
140
Confidence Factor
87.5%
>99.9%
>99.9%
52.0%
>99.9%
>99.9%
>99.9%
Concentration Trend:
Stable
Decreasing
Decreasing
No Trend
Increasing
Decreasing
Increasing
¦&
3
C
O
E
8
C
o
u
fOOOG
Sampling Date
Notes
1. A1 least 'our inttepenaEn: sarnplftg events per wsfl are required for calculating the trend. Meffxxiatogy Js vaM fcr4 to 40 samples
2. Confidence h Trend - Ccredence ;in percent) that ccnsftuent concentration t& Increasing (S»0) a- cteereasng (SdOJc >95% - Increasing or Decreasing;
* 50% - ProoaBy increasing or PrcfcaWy Cecre3sln§; « 90S and 5X1 - No Trend; -c 90%, 5X1, ana GOV s= 1 - No Trend;« 90% ard GOV < 1 - StaOte.
3. Me^Kxtology based on "MARGS: A Decfeon Suooart System for Optimizing Vtonltcmng Plans*, J j. Aztz, M Ling, KS. Rita, C.J. Newel, and JLR. Sonzaes,
Ground Water, 4l{3):3S5-367,20Q3.
DISC LATHER me GS) Manr-K&rtis* Travjr 15 avaiabte "55 is". CansiJetrafly& care .las oeen ex&wed in txeparrg 1m sol!*are cnxTuix towew, nopany, intiwtng Mrinout
frrrawvi GSi ErwonmErtat mates an/ represenHflarii or^a^iy regaTfcnj ff?e aca&acy, hhsc&ibss or oonpseness cf ifte iaamuLii oaranecf.lerei?, ana rosucn
pan}1shaKHe Jy&fe mrar.y c&ecr. .Vx*ec; ccfisequsnna1. ncxfentfar afterdamages lesiOmgltom me use of fws product otUk ntamatian cootihed J&ein. Mtmnaftyi'm
jfts (diirtarop is sutjec; S3 cfiange arrttajr rarae. GSi Bmmrneai fnc, dnsdsns arr/resfonsiimyorawgason rc i^oa® *» iHwnaftan oontametih&wn.
GX EhvTyvscrrlffl i'nc, wm\ gsKKisom
Figure C-2. I.l-DCE concentration trends from 7 of the 13 wells in the A-zone aquifer with exceedances
during the reporting period. Two out of the 13 had increasing trends during the reporting period.
36
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
GS1 MANN-KENDALL TOOLKIT
for Constituent Trend Analysis
Evaluation Date:
Facility Name:
Conducted By:
1 -Mar-21
Hassyampa Landfill
Jeffrey Weiss
Job ID:
Constituent:
Concentration Units:
12DCA
ug-'L
Sampling Point R):| MW-19UA
12DCA CONCENTRATION (ug-l]
IQ-Jan-15
5.5
11-Apr-1c
11-Jul-15
12-Qct-15
9-Jan-16
7.7
S-Apr-16
7.4
15-Jul-17
14-Oct-17
¦"-Jan-18
10
13-Jul-10
4.8
11
12-Aug-19
7.1
11-Jan-20
7.36
"3
11 - Apr-2Q
5.75
14
11-Oct-20
4.92
16
17
1 1
Coefficient of Variation:
0.24
i i i
i i
Mann-Kendall Statistic {3):
Confidence Factor:
-32
iii
95.5%
i i i
Concentration T rend:
Decreasing
Sampling Date
Notes:
1. At least four independent sanding events per well are required fee calculating the trend. Methodok>gy is valid for 4 to 40 samples.
2. Confidence in Trend = Confidence (in percent) that consttuent concentrator? is increasing (S>0) or decreasing i'3<0}: >85% = i ncreasing or Decreas ng;
£ 90% = Probacy Increasing or Probably Decreasing; < 90% and 3>0 = No Trend; < 3D%. SsO, and COV a 1 = No Trend; < 00% and COV < 1 = Stable
3. Methodology based on "MAROS: A Decision Support System for Optimizing Monitoring Plans'". J J. Aziz. M. Ling, H.S. Rrfai, C.J. Newe!, and J.R. Gonzales,
Ground Water, 41(3):355-367, 2Q03.
DISCLAIMER: T?ie GST MtvirhJCamfif TooM is available "as is'. Considerable care has been exercised' fln preparing this software product howeww. no party, induding iwthouf
ifjridJkKJ QSI Envirunrnertal inc., mates any representation or warranty regarding the accuracy, correctness, or completeness of the information contained .herein, and no such
party staff be Xante for any direct indirect conseqi/eriLiet incidental or other damages resulting from the use of tins product or trie information contained herein, flnfomration in
this pubdcatKii is suD/ect to change wrtrwf notice. GS/ Environmental Inc., disdaws any rescfoosibfiity or obGgation to update the infonrsBo'i contained herein.
GSl Environmental Ana. *ww_gshnetcoitf
Figure C-3. 1,2-DCA concentration trend from the one well with exceedances during the reporting
period.
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
37
-------
ug.'L
Sampling Point 10:
MW-06UA
MW-12UA I I I I I I
Event
Date
12DCP CONCENTRATION (ug/L)
1
10-Jan-15
3.5
2
11-Jii-15
3.4
3
12-Oct-15
28
4
9-Jan-16
6.6
5
9-Oct-ie
39
0
15-JuM7
5.6
7
14-Oct-17
43
a
1^Jii-18
6.3
9
e-Oct-ia
35
10
13-Apr-19
8.6
11
9.7
12
12-Aub-19
25
30
13
6-Oct-19
12
27
14
11-Jan-2D
12.7
15
11 -Apr-20
11.4
16
11 -Oct-2C"
10.2
13.3
17
18
19
20
Coefficient of Variation:
Mann-Kendall Statistic (3):
Confidence Factor
Concentration Trend:
0 60 | 0.31
42 -11
I I I I
99.8% | 93 2% |
I I I I
increasing jprob. Decreasing
100
C
o
IP
£
-
a>
o
c
o
u
MA'-G&JA
¦12UA
0S/f3 12/U 05/16 09/17 02/19
Sampling Date
oe^
1W21
Motes:
1. At least XruT ircependent sampling events per wei are required for calculating the trend. Methodology is vafid for 4 to 40 samples.
2. Confidence n Trend = Confidence fin percent) that constituent concentration is increasing (SX)) or decrease (S<0): >95% = Increasing or Decreasing:
2r 90% = Probably Increasing or Probaexy Decreasing; < 90% and S>Q = No Trend;; < 90%r SsO, and COV a 1 = No Trend < 00% and GOV < 1 = Stable.
Methockxogy based on "MAROS: A Deosion Support System far Optimizing Monitoring Plans', J J. Aziz, M_ Ling, M.S. Ritai, CJ. Newel1, and J.R. Gonzales.
Ground Water 41(3):355~367,2003.
DISCLAIMER: The GSJ Mann-Kendai Tooted is avafcbfe 'as is'. Conside/aUe care has been exercised in preparing this software product however, .no party, ire/jding iHtftarf
ferniafon GSf Entfronn?eria/ Inc., makes any rep.'e.s&Ttatbn or warranty regarding the accuracy, correciTess,. crcarapfeteness of the tmbnroton contained here*?, and no such
party shaft be liable for any dueo, indirect, eonsequeotiaf, incidental or other daniages respiting frsrn the use of this product or #ie information contained herein. Information in
ites pufofcatw? is siA&jsci to change mhojt notice. SS/ iBwiForimenM Inc., desdairns an/ responsibility or obligation to update the inranratcn contained ner&fl?.
GSi BMUHBOlal Inc., wm.gsi-veic&ri
Figure C-4. 1,2-DCP concentration trend from the two of the five well with exceedances during the
reporting period. The wells are plotted on separate sheets because of different sampling intervals.
38
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Jeffrey Weiss
ug.1
Sampling Point ®:
EW-04UA
Influent
MW-I8UA
MW-19UA I
Brant
Darts
12DCP CONCENTRATION (uglL)
1
lO-Jan-15
12
8.5
27
7D0
2
1 1-Apr-15
12
29
760
3
11-JuM £
11
910
4
12-Od-15
8J5
5.1
29
SCO
5
9-Jarvt6
7
5.2
28
830
6
9-Apr-15
5.1
5.7
740
7
9-JL--5
5.5
5.2
23
720
8
9-OCM5
5.5
5.4
28
7EO
9
14-jan-t"
5.3
3.7
20
650
10
3-Apr-17
750
It
1E-JUM7
5.9
4.9
20
640
12
14-OCV17
5.3
3.7
23
650
13
7-Jan-i a
5.5
4
30
730
14
7-Apr-13
4J5
3.3
5 ED
15
13-JuMB
4.7
3.3
17
5EO
15
3-QCM8
4.3
3.8
28
6 ED
17
12-Jan-19
4.8
3.2
22
720
18
13-AQM9
4.1
3.1
17
19
8-JUIVl9
630
20
13-JUM9
5.3
4.1
18
560
21
12-Aug-19
19
560
22
5-OCM9
4.7
25
670
23
it-Jan-20
4.95
3.2-3
31.3
973
24
1*,-A0T-2C
4.93
3.43
3C-.1
865
25
11-JUI-2C
4.32
3.37
25.2
854
25
11-OC1-2D
3.84
3.D3
2D.3
646
27
28
29
30
Coefficient of Variation:
0.40
0.32
0.19
0.15
Mann-Kendall Statistic fS):
-181
-127
-25
-69
Confidence Factor:
>99.9%
>99 9%
76.3*
94.4%
I
Concentration Trend:
Decreasing
Decreasing
Stable
Prob. OecraaMig|
1000
aj
a
+•*
E
+*
c
jS*0): >95% - increasing or Decreasing;
a 9C% - Probably increasing or Probably Decreasing; < 90% and S»0 - No Trend; < 90%, SsO. and GOV * 1 - No Trend; ¦= 50% and GOV « 1 - Stable.
3. MethodDtogy Eased on "MAROS: A Decision Support System tor Optimizing Monltortng Plans", JJ. Aziz, M. Ling, H.5. Rffaf, C.J. Newell, and J.R. GonzaJes,
GrauW Water .41 (3):355-367. 20C3.
DfSCLd.'JWER me GSt Mann-xendas TooM is ratable "s-s a". CojiaSeraM* care flas Deep exeresed mpreparing Sis software product; flemever, nopany. fMUtfng arrftM
AcrmraDon GSt Enwronmereal Inc., mates any /ipresemaiwi or warranty' regarding me acorxy, eocEcmess, orccffjc^e.Tess or me informawyi Hvnanstf fie/m and no suet?
parry sftafl be tab/e toranf tinea, indirect Garsequenaa/, .nxientA'or omer damages resu/Ufg !7om fte use orttis product or^e vrtirroaswi contained nereia fnftHTJiaDon in
£iis puzticavon is su«|ecr re charge atfitxiT ootxe. GSt EnwwroenW inc., di&aaros any responsibility or otfgariaa re update are ktumuHurt eontamed herein
SSI EnwarmeTa' fas... www.95t-netcoro
Figure C-5. 1,2-DCP concentration trend from the three of the five well with exceedances during the
reporting period. The wells are plotted on separate sheets because of different sampling intervals.
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
39
-------
Sampling Point ID:
MW-2DUA
MW-01UA
MW-07UA
MW-12UA
Sampling
Event
Sampling
Date
TCE CONCENTRATION (ug/L)
1
11-Apr-15
120
2
12-Oct-15
110
e
28
67
3
G-Apr-16
94
4
Q-Oct-16
33
2
15
94
A.
E-Apr-17
75
6
14-Oct-17
71
2.1
14
130
7
7-Apr-18
67
3
B-Oct-1S
59
2.3
16
SO
9
13-Apr-19
43
10
12-Aug-19
56
11
©-Oct-19
59
2.4
21
63
12
11 -Aor-2G
03.9
13
11 -Oct-2Q
06.5
5.22
27.5
34.9
14
15
16
17
IS
10
20
Coefficient of Variation:
0.28
0.67
0.31
0.40
IB ¦
Mann-Kendall Statistic |S):
-49
5
3
-11
Confidence Factor:
>99.9%
76.5%
64.0%
93.2%
Concentration Trend:
Decreasing
No Trend
No Trend
Prob. Decreasing]
1000
cn
3
C
O
c
o
o
c
o
o
-MW-2DUA
»-MW-C'1 LI A
=MW-D7UA
-MW-12UA
12/14
05/J6
0SW7
02tt9
06/20
ffl2f
Sampling Date
Notes:
1. At least four independent sampling events per we® are required for calculating the trend. Methodology is valid for 4 to 40 samples.
2. Confidence in Trend = Confidence (in percent) that constituent concentration is increasing (S>0) or decreasing (SO): >05% = Ifioreasing or Decreasng;
i 90% = Probably Increasing or ProbaWy Decreasing; < 90% and S>0 = No Trend; < 90%, 3s0„ and COV £ 1 = No Trend; < 90% and COV < 1 = Stable.
Methccology basec on 'MAROS A Decision Support System for Optimizing Monitoring Plans", J.J. Aziz, M. Lingr U.S. Rifaa, C.J. Newell and J.R Gonzales,
Ground Water, 41(3}:355-367, 2003.
Di'SCLA/HER. The 3S/ Mann-K'endaiT Tbolkt is avariabfe 'as is'. Constcterafcte cars .has tieei exercised m preparing this software product: however, /io party, including without
ftfrvtafon GSl Enw.ronmentaf Inc., makes any leptresendaitHW or warranty regaining the accuracy, correctness, or completeness of the iofbTnafiran contained herein, and rx> such
carry s.ha.V tie Eabte for any direct, indirect oonseque/rtiaF, inodentai or other damages resulting from the use of this product or the information contained nerein. Information in
this putifcatfoo is subject to change without notice. GSl Environmental Inc., disclaims any responsibtiity or obligation to update the information contained herein.
GSl Bnmnmenai flic.. www.gsHieteom
Figure C-6. TCE concentration trend from four of the ten wells with exceedances during the reporting
period.
40
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
GSI MANN-KENDALL TOOLKIT
for Constituent Trend Analysis
l-Mar-21
TCE CONCENTRATION (uglt)
0.28 I 0.23 I
138 j -212
mi ii m
Increasing | Decreasing |
a—i |
| Decreasing | Decreasing |
»23
Bi
7S.1*
Stable
I 0 27
-83
M.5%
| Decreasing
Notes:
1. At least four Independent sampling events per well are required Tor calculating the irerel. tJettototoff? Is vaJUS far 4 to 40 samples.
2. ConTVdence in Trend - Confidence »;in percent) tnat constituent concen?3Bon Is increasing (S><]) or decreasing >95% - increasing or Decreasing;
a 90% - Prooaoly increasing or Probably Decreasing; < 50% and S=-0 - No Trend; < 90%, SaO. and GOV * 1 - No Trend; < &Q% and COV •* 1 - StaJMe.
3. Metnodology oased on "MAROS: A Decision Support System for Optimizing MonHortng Ran®", J.J. Aziz, M. Ling. H.5. RPaj, cJ. Newell, and J.R. Gonzales.
Graartf Water, 41{3)35W67.2D03.
Hassyampa Landfill
Jeffrey Weiss
Mo Trend
12-OCt-15
5-Jan-:5
9-Oct-16
14-Jan-17
14-Oct-17
-„3"K 3
7-ApT-18
13-JU-18
12-Jan-1 &
13-JUM9
1 1-Jar-2Q
11-Oct-2Q
11-Apr-15
11-JuMS
9Apr-16
9-JUI-16
S-Apr-17
IS-Jd-17
8-OCt-18
6-oct-is
11-JU-2D
Coefficient of variation: I
Mann-Kendall Statistic ;S|:
Confidence Factor
Concentration Trent
Evaluation Date:
Facility Name:
Conducted By:
Job®:
Constituent
Concentration Units:
-3-Apr--9
B-Jin-19
Sampling Date
ugit
fnfluent 1 MW-Q4UA | EW-03UA I
i 2iU OS/fff
0W17
Q2M9
-------
GSI MANN-KENDALL TOOLKIT
for Constituent Trend Analysis
Sampling Point ID:
MW-20UA
MW-12UA
Sampling
Event
•Sampling
Date
PCE CONCENTRATION (ugfL)
1
11-Apr-15
9.3
2
12-Oct-15
7.1
12
3
c1-Apr-10
9.1
4
&-Oct-10
7.7
17
c
8-Apr-17
5.6
6
14-Oct-17
5.9
22
7
7-Jan-1S
S
7-Aor-18
5.5
9
S-Oet-13
4.4
15
10
13-Apr-19
4.1
11
12-Aug-19
12
12
d-Oct-IS
4
12
13
11 -Apr-20
5.1a
14
11 -Oct-2D
7.56
6.D4
15
16
17
1B
16
20
Coefficient of Variation:
0.29
0.36
I
Mann-Kendall Statistic |S):
-38
-10
I
Confidence Factor
99.6%
90.7*
Concentration Trend:
Decreasing
Prob. Decreasing
C
o
o
o
12/14
W17
02/19
09/20
10/21
Sampling Date
Notes:
1. At least four ^dependent sampling events per well are recpsre^ for calculating the trend. Methcdoiogy is valid for 4 to 40 samples.
2. Confidence in Trend = ConfkSerrce (in percent) foart constituent concentration s increasing (S>0) or cecreasing (S<0): >85% = Increasing or Decreasing;
2 20% = Profeafciy Increasing or Probably Decreasing; < 90% and S>0 = No Trend; < 90%, S£Q. and COV 2 1 = No Tre?vd; < 90% and COV < 1 = Stable.
3. Methodology based on rMARQS: A Derison Support System for Optimizing Monitoring Plans". J J. Aziz, M. Ling, H.S. Rifal C.J. Newell, and J.R. Gonzales,
Ground Wafer. 41(3):355-367.2D03.
D/SCLA/WEfl: The G5J Ifero-ftsndaP Tooflot is avabfafe 'as is* C-c-nstf&aDte ca'e .has been exeflasea" in preparing this so/bum product however, no party, ndudrtg witnoi/f
Am/Jain n GSJ EmnwMimilaf Inc., makes any representation or wanarty reganftig the accuracy, correctness, or co.nTpfeieoess of the information contained /lerewt and no such
party shall be liabte for any direct, incfrect, ranseguentia!1, inadental or other damages ^sufeng from the use of this product or ike information contained herein. Irformaijon in
this pubfeation is subject to change iwtnou! rxawe. GSI Enwonrrertal Inc., disclaims any responstbity or obtigaoon to update the information contained herein.
GSt Envroriroenrai ifnc,, mwigswjetcom
Figure C-8. PCE concentration trend from two of the seven wells with exceedances during the reporting
period.
42
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Sampling Point ID:| MW-19UA
Influent
MW-06UA
EW-04UA
MW-18UA
MW-04UA
PCE CONCENTRATION (ugll_)
1
10-Jan-IS
72
5.6
12
3.9
28
2
11-ADM5
1 ta
7.7
12
11
48
6.9
3
11—J-Ul-15
120
5.9
15
11
44
7.8
4
12-OCM5
91
5.1
11
5.1
29
5.4
5
9-Jan-l6
110
4
15
5.4
36
6.2
6
9-Apr-16
130
44
15
5
35
7.3
7
9-JU-16
120
4.5
14
5.1
31
5.4
B
9-Oct-16
110
4.2
19
4.5
31
5.7
5
14-Jan-17
93
3,4
19
4.5
22
4.8
10
3--Apr-17
91
3.6
15
3.9
21
4.6
11
15-JUI-17
1D0
4.3
17
4.6
25
5.2
12
14-CCJ-17
ieo
3.2
25
4.8
28
5
13
7-jan-l8
110
3.3
20
4.4
23
4.4
14.
7-Apr-1B
130
3
21
4
24
6.4
15
13-JllM 8
too
2.6
23
3.5
17
6.1
16
3-Oct-1E
130
2.9
21
3.3
21
4.7
17
12-Jan-19
98
2
3.2
5.6
18
13-Aar-19
2.2
25
21
5.6
19
S-vUin-19
87
20
13—Jul-19
130
3.2
30
4
24
6.9
21
12-AJQ-19
170
16
26
22
o-OCt-151
14-0
2.6
27
3.2
21
5.4
23
•1-Jan-2Q
156
2
28.3
3.14
24.5
5.79
24
11-/-J3T-20
2D3
2.18
27.7
3.52
28
7.29
25
11-JUI-20
1C6
226
26.9
3.06
26
11-OCS-20
140
2.15
28.9
3.16
22-2
7.28
27
28
29
30
Coefficient of Variation:
0.2S
0.40
0.30
0 46
0.27
0.17
Mann-Kendall Statistic (S|:
96
-216
200
-207
-110
2
Confidence Factor
98.7%
>99.9%
>99.9%
>99.9%
99.9%
51.1% J ZD
Concentration Trend:
In creasing
Decreasing
Increasing
Decreasing
Decreasing
No Trend
1£HW
=d
O)
c
.2
a
a
o
O
100
-MWM9UA
»lfrtuent
-MiVOSUA
¦EW-WUA
"MW-04UA
W13
12/14
0&16
£Wf7
02/18
0&70
1071
Sampling Date
Notes:
1. At least Tour independent sampling events per well a?e requires for calculating the tram, Methodology is vaaa for 4 to 40 samples.
2. Confidence in Trend - Confidence On percent) that consttuent concentration is increasing (S>0) or decreasing (S95% - increasing or Decreasing;
t 50% - Pro&aTHy increasing er Probably Decreasing; < 90% and S»0 - Mo Trend; < 90%, SsC>, aid COV * 1 - Mo Trend; « 90% and GOV «1 - stable.
3. Mefiodol&gy based on "WARDS: A Decision .Support System Tor Oplrntzlng MonHoring Plans', J.J. Aziz, M. Ling, H.S. Rffal, C.J. Newell, and J.R. Gonzales,
Ground Wafer, 41(3}:355-367, 2DG3.
DiSCLAMER 7?ie GSf Mann-Kendai "oottt is avarfaWe "as is*. considerable care ftas !>?en ejceresed .if? pnspanrjg tfvs software produce fioaever, ,no party, including wnnot/r
tmtaew? GSI En wTKKTse.niai iYk;,. makes any representation or aaTarH)' regartfi'ng tf>e accuracy, correctness. Of oorra3i£reoes-s of me intofmatjon contained nerein, ana no s/tf?
par?}' sftav be iatite for any d.Vect indirect, consequential, incidental urotner damages renting (torn me use of ihis pmductonte infGirnanbn oorxai'nea nerevn. {rfiyrnason in
ttiis puMieaSor? is sufijecr ro etange nwftour no&e. GSl BnmnmerSai Inc, ctea'ai'ns any response*!)' or obligation jd uyxflre £fre ntxTnaoon corawd fieren
GSfEnH>D/w?en{afliB, ¦*n*w.g:i-'wiC'Un
Figure C-9. PCE concentration trend from five of the seven wells with exceedances during the reporting
period.
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
43
-------
GSI MANN-KENDALL TOOLKIT
for Constituent Trend Analysis
Evaluation Date:
l-Mar-21
Job ID:
Facility Name:
Hassyampa Landfill
Constituent
BZ
Conducted By:
Jeffrey Weiss
Concentration Un'rta:
mg/L
Sampling Point ID:
MW-19UA | | | | | | |
Sampling
Event
Sampling
Date
BZ CONCENTRATION (mg/L)
t
10-Jan-15
5
2
11-Apr-1c
5.9
3
11-JuM5
7.S
4
12-Oct-15
6.3
g
9-Jan-16
6.7
6
¦5-Apr-16
6.5
7
14-Oct-17
7
8
7-Jan-18
6.2
9
13-JuHB
5.8
10
12-Aug-19
Ft
11
11-J an-20
3.33
12
11 -Apr-20
6.44
13
11 -Oct-20
6.27
14
15
16
17
IS
IS
20
Coefficient of Variation:
0.15
Mann-Kendall Statistic |S):
3
Confidence Factor:
¦ 54.8% I
Concentration Trend:
No Tren d
w
c
o
c
9
o
c
o
o
W/-19UA
1 —
mwj
11/14
05/16
09/17
02/19
06M
10/21
Sampling Date
Notes:
1. At least four independent sampling events per we® 3re required for calculating the trend. Methodology is valid for 4 to 40 samples.
2. Confidence in Trend = Confidence (in percent) that constituent concentration is increasing (S>0) or decreasing (3<0): >65% = Increasing or Decreasing;
2 SD% = Probably Increasing or Probably Decreasing; < 90% and S>0 = No Trend < 90%, S£Q, and COV £ 1 = No Trend: < ©0% and COV < 1 = Stable.
Methodology based on 'MAROS: A Decision Support System for Qptimzing Monitoring Plans' J.J- Aziz, M. Ling. H.S. Rifiai, C.J. Newell, and J.R. Gonzales,
Ground Water, 41(3):355-367, 2003.
DISCLAIMER: The GSJ Mann-Ken daf Too'kit is available 'as is' Considerable care has beer, exercised in preparing this software product however, no party, including without
finutafon GS! Environmental inc.. makes any representation or warranty regarding the accuracy, correctness, or completeness of the information contained herein, and no such
party shall be table for any direct indirect consequential, incidental or other damages resulting from the use of the product or the hfannatian contained herein. Anfermacion in
this pubrtca&on is subject to change wdfrotir nonce. GS/ Enwrammental be., disclaims any r&sponsbHity or obligation to update the ^formation contained herein.
GSI Elvironmenai flic., mwgsi-ng.com
Figure C-10. Benzene concentration trend the one well with exceedances during the reporting period.
44
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Appendix D: Applicable or Relevant and
Appropriate Requirements
Assessment
Section 121 (d)(2)(A) of Comprehensive Environmental Response, Compensation, and Liability Act
specifies that Superfund remedial actions must meet any Federal standards, requirements, criteria, or
limitations that are determined to be legally applicable or relevant and appropriate requirements
(ARARs). ARARs are those standards, criteria, or limitations promulgated under Federal or State law that
specifically address a hazardous substance, pollutant, contaminant, remedial action, location, or other
circumstance at a Comprehensive Environmental Response, Compensation, and Liability Act site.
Changes (if any) in ARARs are evaluated to determine if the changes affect the protectiveness of the
remedy. Each ARAR and any change to the applicable standard or criterion are discussed below.
Chemical-specific ARARs identified in the 1992 Record of Decision for groundwater were evaluated
(Table D-l). There have been no changes to groundwater chemical specific ARARs in the last five years.
Site contaminants identified in Table D-l that do not have any state or Federal regulations are toxicity
based and are evaluated in the Toxicity Analysis (Appendix E).
Table D-1. Summary of Groundwater Chemical-Specific ARAR Changes
Chemical
1992 ROD
Cleanup
Levels (ng/L)
Basis for Cleanup
Level
Current Regulations (ng/L)
ARARs More or
Less Stringent
than Cleanup
Levels?
State
[if applicable]
Federal
Benzene
5
Federal MCL
5
5
No changes
Dichlorodifluoromethane
(Freon 12)
1,400
State HBGL
N/A
N/A
N/A
1,1 -Dichloroethene
7
Federal MCL
7
7
No changes
1,1 -Dichloroethane
N/A
No cleanup
standard selected
N/A
N/A
N/A
1,1,1 -Trichloroethane
200
Federal MCL
200
200
No changes
1,2-Dichloroethane
5
Federal MCL
5
5
No changes
C is-1,2 -Dichloroethene
70
Federal MCL
70
70
No changes
Trans-1,2-
Dichloroethene
100
Federal MCL
100
100
No changes
1,2-Dichloropropane
5
Federal MCL
5
5
No changes
Acetone
700
State HBGL
N/A
N/A
N/A
Chlorobenzene
100
Federal MCL
N/A
100
No changes
Trichlorofluoromethane
(Freon 11)
2,100
State HBGL
N/A
N/A
N/A
T richlorotrifluoroethane
(Freon 113)
210,000
State HBGL
N/A
N/A
N/A
Methyl Ethyl Ketone
170
State HBGL
N/A
N/A
N/A
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
45
-------
Chemical
1992 ROD
Cleanup
Levels (ng/L)
Basis for Cleanup
Level
Current Regulations (ng/L)
ARARs More or
Less Stringent
than Cleanup
Levels?
State
[if applicable]
Federal
Dichloromethane
5
Proposed Federal
MCL
5
5
No changes
T etrachloroethene
5
Federal MCL
5
5
No changes
Toluene
1,000
Federal MCL
1,000
1,000
No changes
Trihalomethanes
100
Federal MCL
80
80
No changes
Trichloroethene
5
Federal MCL
5
5
No changes
Chromium (total)
50
Federal MCL
N/A
50
No changes
Xylenes (total)
10,000
Federal MCL
10,000
10,000
No changes
Vinyl chloride
2
Federal MCL
2
2
No changes
HBGL=Health Based Guidelines
Federal and State laws and regulations other than the chemical-specific ARARs discussed in Table D-l
that have been promulgated or changed since the 1992 Record of Decision are described in Table D-2.
There have been no revisions to laws or regulations that affect the protectiveness of the remedy.
The following action- or location-specific ARARs have not changed in the past five years, and therefore
do not affect protectiveness:
• Safe Drinking Water Act (42 USC 300f)
• Endangered Species Act (16 USC 1531 et seq.; 50 CFR200 and 402)
• National Archeological and Historic Preservation Act (16 USC 469; 36 CFR Part 79)
• National Environmental Policy Act (NEPA) Floodplain Management Procedures (40 CFR 6
Appendix A; Executive Order 11988)
• Fish and Wildlife Coordination Act (40 CFR 6.302)
• Protection of Riparian Areas (Executive Order No. 91-06 of the governor's office of Arizona)
• RCRA standards for miscellaneous units (e.g., air strippers) (40 CFR 264, Subpart X)
• Clean Air Act (42 USC 7401; 40 CFR 50-99)
• Installation permits to make alterations to machinery (49 ARS 480)
• Land Disposal Restrictions (LDRs) (40 CFR 268, Subpart D)
• Requirements for capping and cap maintenance of Hazardous Waste TSD Facilities (40 CFR, 265.310
and 265.117)
• Underground injection of treated groundwater (UIC Permit) (40 CFR 144-146)
• Arizona Aquifer Protection Permit (APP) (49 ARS 242-249, and AAC R18-9-102 to R18-9-403)
• RCRA Hazardous Waste Management System (40 CFR Part 260)
• Groundwater Monitoring (40 CFR 265 Subpart F)
• Arizona Health-Based Guidance Levels (HBGLs) set by Arizona Department of Health Services
• Control of volatile organic compounds and gaseous contaminants (Maricopa County rules 320 and
330)
• Control of emissions from air strippers exceeding 3 pounds/hour (EPA OSWER Directive 9355.0-28)
46
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Table D-2. Summary of ARAR Changes for Site in the Past Five Years
Requirement and Citation
Document
Description
Effect on
Protectiveness
Comments
Recent Amendment
Date
Fish and Wildlife
Coordination Act (16 USC
661)
1992 ROD
Game, Fur-bearing
animals, and fish
Changes do not affect
protectiveness.
Pub. L. 116-9 inserted
section catchline, designated
existing provisions as
subsec. (b), inserted
heading, and added subsec.
(a).
2019
RCRA TSDF standards for
control of volatile organic
compounds (40 CFR 264,
subparts AA and BB)
1992 ROD
Air Emission Standards
for Process Vents and
Equipment Leaks
Changes do not affect
protectiveness.
Edits to Notes
Subpart AA revised in
2017
Subpart BB revised in
2019
Underground injection of
treated groundwater (UIC
Permit) (40 CFR 147)
1992 ROD
State, Tribal and EPA
administered underground
injection control programs
Changes do not affect
protectiveness.
Subpart ZZ changes to State
ofWY injection wells.
2020
RCRA Hazardous Waste
Management System (40
CFR Part 260)'
1992 ROD
Hazardous Waste
Management System
Changes do not affect
protectiveness
Edits to 260.11
2020
Use and management of
containers (40 CFR
264.170-264-179)
1992 ROD
Standards for owners and
operators of hazardous
waste treatment, storage,
and disposal facilities
Changes do not affect
protectiveness
Edit to the purpose and
scope section
2020
Maricopa County Rule 210
1992 ROD
Describes title V permit
requirements, application
procedures for new title V
sources, and application
procedures for
modifications to existing
title V sources.
Changes do not affect
protectiveness.
Adopted December 11,2019
2019
Arizona Aquifer Protection
Permit (APP) (49 ARS 241
and 250 andAACR18-9-
101)
1992 ROD
Aquifer Protection Permit
Changes do not affect
protectiveness.
49 ARS 241 has been taken
out of the regulation
49 ARS 250: exemption for
class V wells
AAC R18-9-101: Amended
by final expedited
rulemaking at 25 A.A.R.
3060
49 ARS 241: January
29,2021
49 ARS 250: January
29,2021
AAC R18-9-101:
September 23, 2019
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
47
-------
Appendix E. Toxicity Assessment
Chemical-specific applicable or relevant and appropriate requirements identified in the 1992 Record of
Decision for groundwater were evaluated (Table E-l). EPA adopted Regional Screening Levels as
screening levels for residential and commercial worker risk exposures. EPA's Integrated Risk
Information System updates toxicity values used by EPA in risk assessment when newer scientific
information becomes available, and the most recent update available for the Five-Year Review was in
May 2021.
Changes have occurred to some Regional Screening Levels since the 1992 Record of Decision (Table
E-l). All changes fall within EPA's generally acceptable risk range of 1 x 10"4 to 1 x 10"6 as discussed
in the National Oil and Hazardous Substances Contingency Plan, so the changes do not affect
protectiveness.
Table E-1. Comparison of Tap Water RSL to Record of Decision Cleanup Standards
Chemical
Hassayampa
Groundwater
Cleanup
Standard
Basis for Cleanup
Level
Current Tap
Water RSL
c = cancer
n = noncancer
RSLs
More or
Less
Stringent
than
Cleanup
Levels?
Dichlorodifluoromethane
(Freon 12)
1,400
Based on non-cancer
hazard index of 1
200 (n)
More
stringent
1,1 -Dichloroethane
No cleanup
standard
selected
2.8(c)
N/A
Acetone
700
Based on non-cancer
hazard index of 1
14,000 (n)
Less
stringent
Trichlorofluoromethane
(Freon 11)
2,100
Based on non-cancer
hazard index of 1
5,200 (n)
Less
stringent
Trichlorotrifluoroethane
(Freon 113) aka 1,1,2-
trichloro-1,2,2-
trifluoroethane
210,000
Based on non-cancer
hazard index of 1
10,000(n)
More
stringent
Methyl Ethyl Ketone
170
Based on non-cancer
hazard index of 1
5,600 (n)
Less
stringent
c = cancer, n = noncancer, RSL = Regional Screening Level
While the current tap water regional screening level for dichlorodifluoromethane is significantly less
than the cleanup standard, a review of sampling results during the reporting period found all samples
reported as non-detect. All sample results for Trichlorotrifluoroethane were below the regional
screening level for this reporting period.
Fifth Five-Year Review for the Hassayampa Landfill Superfund
48
-------
Appendix F: Public Notice
@
EPA Begins Ravlew of Hassayampa Landfill Suporfund Cleanup Plan
The U.S Environmental Protection Agency (EPA) has started rts fifth Five-Year Review for the Hassayampa
Landfill Superfund stte cleanup plan The 10-acre site is about 10 miles west of Buckeye. Ariz Mancopa
County formerly used the site for hazardous waste disposal In 1992, EPA issued its cleanup plan for the
site Cleanup work began in 1994.
Federal law requires EPA to review its cleanup plans every five years if;
a cleanup takes more than five years to complete; or
hazardous waste is still on-site
The Flve-Year Review will show if the cleanup plan continues to work as designed EPA did the last such
review In 2016 and the next one » due by September 30. 2021,
What does the review Include?
The 2021 Five-Year Review Includes:
• an inspection of the site and its cleanup technologies;
• a review of site data and maintenance records, and
• a review of any new laws or requirements that could affect the cleanup
We would like to hear from youl
We would like to interview community members about how you think the site cleanup is going. If you would
like to learn more about the site and/or be interviewed, please contact the EPA project manager below
before March 31, 2021:
Nadia Hollan Burke, EPA, 415-972-3187, BurKe NadjaHoltan®epi9 AOY
Where can I leam more?
Visit EPA's site webpage at epa gov/superfund/hasavamoalandfjll and the Arizona Department of Environ-
mental Quality's (ADEQ) site webpage at aHlW.gOV/5UpfiriUIKl/ha55ayanipa:laDdfil! for more information
EPA and ADEQ plan to post the complete Five-Year Review report on these websites within the first week of
October 2021.
You may review site Information at the ADEQ Records Center, 1110 W. Washington Street Phoenix, AZ
85007 For information on requesting records, please call ADEQ at (602) 771-4380 or visit their website
ozdeq.BOv/fBwrd# center cnmmukm
I
Fifth Five-Year Review for the Hassayampa Landfill Superfund
49
-------
Appendix G: Interview Forms
Five-Year Review Interview Record
Site:
Hassayampa Landfill
EPA ID No: AZD980735666
Interview Type: Filling-in Interview Record
Location of Visit: N/A
Date: February 8, 2021
Time: N/A
Interviewers
Name
Title
Organization
Interviewees
Name
Organization
Title
T elephone
Email
Dave Becker
USACE
Geologist
Hugh Rieck
USACE
Geologist
Summary of Conversation
1)What is your overall impression of the project?
The project is relatively stable. There are no known exposures, nor are any imminent. Progress is being made on vadose zone remediation by
the soil vapor extraction and treatment, but groundwater extraction and treatment to contain groundwater contamination on-site will be on-
going for decades (if not centuries) under the current approach. The relationship between the agencies and the HSC is constructive.
2) Is the remedy functioning as expected? How well is the remedy performing?
The remedy is generally functioning as intended, though progress toward the goal of restoration of groundwater is not occurring at an
appreciable rate, and in some cases, groundwater concentrations in a few wells near the Pit 1 source area have increased in the last three
years for unknown reasons. However, data from the second half of2020 may suggest the trend may not persist.
3) What does the monitoring data show? Is contaminant containment occurring?
The monitoring data indicate the groundwater plume in Unit A is generally contained by the extraction system; and contamination has not
migrated downward to Unit B, nor is it expected to do so. Soil vapor concentrations have generally and substantially declined except near
SP-1 (and this is not considered a direct risk to the groundwater as the contaminants are predominantly degradable hydrocarbons, e.g.,
xylenes, and the detections are separated from the water table by a thick basalt layer and the site is capped). There have been some detections
of contaminants in wells south of the municipal landfill, that are not suspected of being related to the Superfund site. Again, the increased
concentrations of some VOCs in groundwater near the Pit 1 source area during the last 3 years or so are difficult to explain and require
additional discussion.
4) Please describe the frequency of site inspections and maintenance visit activities in the last five years.
Our understanding is the site is inspected every month, and personnel respond to alarm conditions on the equipment. Detailed inspection and
air stripper cleaning are conducted at least annually, though there may be more frequent cleaning done, if necessary. USACE provides
oversight of the annual cleaning, usually conducted in October of each year.
5) Have there been any significant changes in the Operations & Maintenance requirements, maintenance schedules, or sampling
routines in the last five years? If so, do they affect protectiveness of the remedy? Please describe changes and impacts.
There have been adjustments in the sampling of soil gas to support the updated soil vapor extraction decision logic, with an emphasis on
monitoring points near Pit 1. There has been a permanent change from the GEO condensation treatment to carbon adsorption. This has
reduced O&M effort (and cost). There have been some minor modifications to the groundwater sampling program that would be described in
the Annual Reports.
6) Have there been unexpected Operations & Maintenance difficulties or costs at the site in the last five years? If so, please give
details.
No, nothing unexpected.
7) Have there been opportunities to optimize Operations & Maintenance or sampling efforts? Please describe changes and resultant
or desired cost savings or improved efficiency.
Yes, modifications to the sampling program are typically proposed in the Annual Report and evaluated by the agencies. Any apparent O&M
issues are raised by the HSC and discussed with the agencies to identify approaches for improvement that are reliable, cost-effective, and
green. The transition to vapor-phase carbon for SVE effluent treatment in 2016 is a good example.
8) Are you aware of any changes in Federal/State/County/Local laws and regulations that may impact the protectiveness of the
remedy?
No.
9) Are you aware of any changes in the nearby land use in the last five years?
The operations at the Hickman Egg Operations appear to have expanded over the last several years including facilities northwest of the site.
10) Are you aware of any vandalism at the site in the last five years?
Not that has been reported to the agencies.
11) Do you have any comments, suggestions, or recommendations regarding the project?
None, other than what is contained in the responses above.
Additional Site-Specific Questions
None
50
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Five-Year Review Interview Record
Site:
Hassayampa Landfill Superfund Site
EPA ID No:
AZD980735666
Interview Type: Filling-in Interview Record
Location of Visit: N/A
Date: February 11, 2021
Time: N/A
Interviewers
Name
Title
Organization
Interviewees
Name
Organization
Title
Telephone
Email
Tim Little
Maricopa County
Risk Control and Loss Prevention Mgr.
Summary of Conversation
1) What is your overall impression of the project?
I am the representative to the Hassayampa Steering Committee (HSC) for Maricopa County. I believe the project is well organized, well
managed, and is making steady progress towards resolution.
2) Is the remedy functioning as expected? How well is the remedy performing?
The remedy is performing according to predictions.
3) What does the monitoring data show? Is contaminant containment occurring?
Data shows steady progress in the removal of contaminants from soil vapor and from groundwater.
4) Please describe the frequency of site inspections and maintenance visit activities hi the last five years.
Staff from the Maricopa County Environmental Services Department, Waste Resources and Recycling Department are on site quarterly for
purposes of sampling. Maricopa Risk Management staff in on site twice per year and additionally if circumstances require.
5) Have there been any significant changes in the Operations & Maintenance requirements, maintenance schedules, or sampling
routines in the last five years? If so, do they affect protectiveness of the remedy? Please describe changes and impacts.
To the best of my knowledge, there have been no significant changes in the last 5 years.
6) Have there been unexpected Operations & Maintenance difficulties or costs at the site hi the last five years? If so, please give
details.
Other than reports of occasional minor issues, there have been no reports of significant issues.
7) Have there been opportunities to optimize Operations & Maintenance or sampling efforts? Please describe changes and resultant
or desired cost savings or unproved efficiency.
With the length of time this project has been underway, I believe that maximum efficiencies have been achieved.
8) Are you aware of any changes in Federal/State/County/Local laws and regulations that may impact the protectiveness of the
remedy?
No.
9) Are you aware of any changes in the nearby land use in the last five years?
There are no land use changes in the vicinity.
10) Are you aware of any vandalism at the site in the last five years?
None that I am aware of.
11) Do you have any comments, suggestions, or recommendations regarding the project?
Maricopa County is satisfied with the remediation activities, the progress being made, the overall management of the project and the
communications received regarding the project. No suggestions or recommendations at this time.
Additional Site-Specific Questions
None
Five-Year Review Interview Record
Site:
Hassayampa Landfill
EPA ID No: AZD980735666
Interview Type: Filling-in Interview Record
Location of Visit: N/A
Date: February 23, 2021
Time: N/A
Interviewers
Name
Title
Organization
Interviewees
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
51
-------
Name
Organization
Title
Telephone
Email
Colin Wagoner
CALIBRE Systems, Inc.
Consultant to ADEQ
Summary of Conversation
1) What is your overall impression of the project?
Hie project is running smoothly. The groundwater remediation system (GRS) is effectively containing the plume and
removing small amounts of volatile organic compounds (VOCs). The soil vapor extraction system is removing significantly
larger quantities of VOCs. The reporting and communications are timely and clear.
2) Is the remedy functioning as expected? How well is the remedy performing?
Yes, the remedy is preforming as expected. The GRS is effectively containing the groundwater plume onsite. The vapor plume
is decreasing in size due to ongoing operation of the SVE system.
3) What does the monitoring data show? Is contaminant containment occurring?
VOCs in groundwater are localized to a few wells. VOCs in soil vapor are decreasing in size.
4) Please describe the frequency of site inspections and maintenance visit activities in the last five years.
I have not been to the site.
5) Have there been any significant changes in the Operations & Maintenance requirements, maintenance schedules, or sampling
routines in the last five years? If so, do they affect protectiveness of the remedy? Please describe changes and impacts.
The O&M requirements have not generally changed. There have been ongoing efforts to turn off the SVE system but to-date
the concentrations of one or more compounds have rebounded and the system has been restarted.
6) Have there been unexpected Operations & Maintenance difficulties or costs at the site in the last five years? If so, please give
details.
There have been occasional short shutdowns due to power outages or equipment malfunctions, but contractors have dealt with
these in a timely manner.
7) Have there been opportunities to optimize Operations & Maintenance or sampling efforts? Please describe changes and resultant
or desired cost savings or improved efficiency.
The HSC has conducted several SVE rebound tests over the last few years in an attempt to justify turning off that system. In
each case, the soil vapor concentrations have rebounded. Should the current (or subsequent) rebound tests prove successful,
the operating costs will undoubtedly decrease.
8) Are you aware of any changes in Federal/State/County/Local laws and regulations that may impact the protectiveness of the
remedy?
Not to my knowledge.
9) Are you aware of any changes in the nearby land use in the last five years?
Not to my knowledge.
10) Are you aware of any vandalism at the site in the last five years?
Not to my knowledge.
11) Do you have any comments, suggestions, or recommendations regarding the project?
O&M seems routine. The groundwater data suggest that the GRS will need to be operated indefinitely. If the SVE system can
be shut down, efforts to reduce reporting costs should be considered.
Additional Site-Specific Questions
None
Five-Year Review Interview Record
Site:
Hassayampa Landfill
EPA ID No:
AZD980735666
Interview Type: Filling-in Interview Record
Location of Visit: N/A
Date: February 25, 2021
Time: N/A
Interviewers
Name
Title
Organization
Interviewees
Name
Organization
Title
Telephone
Email
Natalie Romanoff
Arizona Department of
Environmental Quality
Project Manager
Summary of Conversation
52
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
1) What is your overall impression of the project?
Hie project is progressing as expected. Communication among all parties is ongoing and beneficial. The remedy is effectively
containing and removing VOCs from the groundwater and soil.
2) Is the remedy functioning as expected? How well is the remedy performing?
The remedy is functioning and performing as expected. Groundwater and vapor plumes are contained and decreasing in size.
3) What does the monitoring data show? Is contaminant containment occurring?
Impacts to groundwater are limited to a few onsite wells and the vapor concentrations are below the Soil Vapor Performance
Standards (SVPS). The SVE system was shut down during rebound testing and restarted after several months of monitoring
due to increasing concentrations for several contaminates of concern.
4) Please describe the frequency of site inspections and maintenance visit activities in the last five years.
Shortly after my onset as Project Manager, ADEQ staff performed one site visit in May 2020. During the last year, field
activities were limited by the agency in response to COVID-19 infection numbers.
5) Have there been any significant changes in the Operations & Maintenance requirements, maintenance schedules, or sampling
routines in the last five years? If so, do they affect protectiveness of the remedy? Please describe changes and impacts.
Equipment malfunctions occasionally occur and result in system shutdowns. The contractor is timely in their responsiveness
to the equipment failure minimizing the shutdown times and ensuring the protectiveness of the remedy.
6) Have there been unexpected Operations & Maintenance difficulties or costs at the site in the last five years? If so, please give
details.
Periodic power outages at the site have caused system shutdowns. However, the contractor responded to the outages, restarted
the system, and communicated issues in a timely manner. The age of the system has resulted in increased equipment
malfunctions causing system shutdowns. The contractor is very responsive to repairing and restarting the system in a timely
manner.
7) Have there been opportunities to optimize Operations & Maintenance or sampling efforts? Please describe changes and resultant
or desired cost savings or improved efficiency.
Yes, rebound testing occurred on the SVE system. However, after several months of monitoring during the rebound test period
several VOC concentrations increased to SVPS. These increases lead to the decision to restart the system and perform rebound
testing again at a future date.
8) Are you aware of any changes in Federal/State/County/Local laws and regulations that may impact the protectiveness of the
remedy?
No.
9) Are you aware of any changes in the nearby land use in the last five years?
No.
10) Are you aware of any vandalism at the site in the last five years?
No.
11) Do you have any comments, suggestions, or recommendations regarding the project?
The remediation systems are kept in good working condition due to routine and regular maintenance. However, the age of the
system does have the potential to increase maintenance costs, as made evident by the reported equipment failures and
malfunctions. Within the next 5 years Groundwater Remediation System equipment nearing the end of life should be replaced
and rebound testing of the SVE system should be reattempted.
Concerning the power outages, countenneasures should be discussed to reduce the frequency, especially during the summer
monsoon season.
Additional Site-Specific Questions
None
Five-Year Review Interview Record
Site:
Hassayampa Landfill
EPA ID No:
AZD980735666
Interview Type: Filling-in Interview Record
Location of Visit: N/A
Date: February 23, 2021
Time: N/A
Interviewers
Name
Title
Organization
Interviewees
Name
Organization
Title
T elephone
Email
Adam King
Geosyntec
Principal Engineer
Summary of Conversation
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
53
-------
1) What is your overall impression of the project?
I have been working on the project since 2009. In 2006 the SVE system was restarted and was aggressively operated targeting
areas of the Site with the highest concentrations of VOCs, resulting in removal of over 110-tons of mass to date. Since the
development and Agency approval of the soil vapor performance standards (SVPS), three rounds of rebound testing of the
SVE system have been conducted indicating that permanent shut down of the SVE remedy may be possible in the near future.
The aggressive mass removal efforts will serve to maintain protectiveness over the long term. At the same time frame the
groundwater recovery system (GRS) has also been relatively continuously operated providing containment of VOCs in
groundwater with some additional mass removal.
The HSC has also worked closely with the Agencies over the last 15 years to address questions or concerns that have arisen.
The HSC has more recently worked with the Agencies to finalize performance standards and operational protocols contained
in the performance monitoring and verification plan (PMVP) to guide later operation and eventual shutdown of the SVE and
GRS remedies. In summary, site conditions are understood, the remedies are operating as intended and plans have been
developed and approved to guide future operation of the SVE and GRS systems.
2) Is the remedy functioning as expected? How well is the remedy performing?
Both the GRS and SVE remedies are functioning as designed and expected. Capture of VOC affected groundwater has been
maintained by the GRS. The operational configuration of the SVE system has also been transitioned to carbon for off-gas
treatment due to the declining influent concentrations and mass removal rates that were experienced in 2015. Since initially
achieving soil vapor performance standards (SVPSs) which supported conducting rebound testing, the operation of the carbon
based SVE system is currently being focused on controlling concentration rebound in the Pit 1 area. Previous Agency
questions regarding capture of VOC affected groundwater along the eastern side of the Site as well as potential vertical
migration to Unit B have also been addressed.
3) What does the monitoring data show? Is contaminant containment occurring?
Groundwater and soil vapor conditions are frequently monitored to demonstrate contaminant containment and steady progress
towards remedial goals. Through operation of the SVE system, soil vapor data have exhibited significant declines, where the
magnitude and extent of the VOCs in soil vapor have been dramatically reduced in comparison to conditions in 2006 when
SVE was restarted. Per the Agency approved PMVP, soil vapor VOC concentrations in the Pit 1 source area have been
reduced to levels that support rebound testing and possible shutdown. Reductions in soil vapor VOC concentrations have
resulted in commensurate declines in influent VOC concentrations to GRS. These data trends continue to support the
Conceptual Site Model (CSM) for the Site that was jointly prepared with the Agencies. Earlier Agency questions with respect
to contaminant of VOC affected groundwater were addressed with the replacement of monitoring well MW-21UA and
installation of MW-21UB. The underlying Unit B groundwater continues to be regularly monitored.
4) Please describe the frequency of site inspections and maintenance visit activities in the last five years.
The Hassayampa Site does not have personnel on-Site continuously performing O&M. The SVE and GRS operations are
automated and equipped with sensors and preprogramed shutdown thresholds. Systems also include telemetry to notify the
appropriate O&M contractor in event of any upset condition so that timely corrective measures can be implemented. Over the
last 5 years, the contractors have met approximately semi-annually which typically include site visits by project managers to
evaluate site and system conditions. Semi-annual meetings with EPA and ADEQ personnel and contractors have also been
held to provide updates of on-going work at the Site, review plans for upcoming work and to review and discuss the results of
sampling events. Conference calls and net-meetings with EPA and ADEQ personnel are also held as needed or requested to
provide updates of on-going work at the Site, resolve questions and review plans for upcoming work.
Over the past 5-years, groundwater related site activities have included monthly inspections in addition to responding to any
alarm conditions from the GRS and quarterly groundwater monitoring activities. Beginning in 2016, the full-scale granular
activated carbon (GAC) system was initiated for extraction and off-gas treatment of VOCs in soil vapor. The switch to the
GAC SVE system included some changes in the O&M performed for the SVE system. Soil vapor monitoring is also
performed semi-annually following an approximate 1-week shutdown of the SVE system (non-extracting conditions). Per the
Agency approved PMVP, rebound testing have been completed to date. All of the data from O&M visits, inspections and
sampling events are submitted to Agencies in the routine semi-annual and annual reports for the Site.
5) Have there been any significant changes in the Operations & Maintenance requirements, maintenance schedules, or sampling
routines in the last five years? If so, do they affect protectiveness of the remedy? Please describe changes and impacts.
Except for SVE system rebound testing initiated in 2017 and a groundwater recovery test in 2020, there have not been any
significant changes in the O&M requirements or maintenance schedules in the last 5 years. The groundwater sampling
program still includes additional analyses for nitrates and 1,4-dioxane as requested by EPA. Reductions in sampling
frequencies at a number of soil vapor and groundwater points based upon statistical evaluations of trends as reported in the
2020 Annual Report have been implemented with approval of the Agencies. The significant mass removal from the vadose
zone of over 110-tons has resulted in a commensurate decline in influent VOC mass to the GRS which results in an increase in
the protectiveness over the long term.
6) Have there been unexpected Operations & Maintenance difficulties or costs at the site in the last five years? If so, please give
details.
There have not been any unexpected difficulties with O&M of the systems that could not be addressed with replacement parts
or repairs to elements such as pumps, level controls, belts, etc.
54
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
7) Have there been opportunities to optimize Operations & Maintenance or sampling efforts? Please describe changes and resultant
or desired cost savings or improved efficiency.
Due to declining influent concentrations, a full-scale pilot test of an air phase granulated activated carbon off gas treatment
system was successfully implemented in 2015 and was made full scale in 2016. As a result, operating costs, including energy
costs have been reduced due to a change from the cryogenic treatment system and carbon consumption has steadily declined.
8) Are you aware of any changes in Federal/State/County/Local laws and regulations that may impact the protectiveness of the
remedy?
No.
9) Are you aware of any changes in the nearby land use in the last five years?
Hickman's Family Farms expanded its egg production facility and added a waste drying facility to produce fertilizer for
nearby farms and a new deep groundwater well. There have been no other significant land use changes since the last 5-year
review.
10) Are you aware of any vandalism at the site in the last live years?
As a result of the HSC's combination of well-maintained security fencing and nightly patrols there have been no vandalism at
the site in the last five years.
11) Do you have any comments, suggestions, or recommendations regarding the project?
Both the SVE and GRS remedies are operating as designed. The SVE system has been highly effective at removing VOC
mass from the vadose zone and has been showing signs of asymptotic mass removal. This condition is supported by initially
achieving SVPSs in 2017 which supported rebound testing of the SVE system. As of the 2020 Annual report, a third rebound
test of the SVE system has been completed, where rebound testing should be maintained to support eventual shutdown of the
active SVE remedy, which will save costs and reduce energy consumption. The SVPSs which are used to guide rebound
testing were developed throughout the 5-year review period, resulting in containment of VOC affected groundwater and some
mass removal. Efforts should continue to maintain consistent GRS operation and containment of VOCs in groundwater per the
PMVP.
Additional Site-Specific Questions
None
Five-Year Review Interview Record
Site:
Hassayampa Landfill
EPA ID No: AZD980735666
Interview Type: Filling-in Interview Record
Location of Visit: N/A
Date: February 10, 2021
Time: N/A
Interviewers
Name
Title
Organization
Interviewees
Name
Organization
Title
T elephone
Email
Ben Costello
HSC/NES
Project Manager
Summary of Conversation
1) What is your overall impression of the project?
I am the Project Manager for the Hassayampa Steering Committee (HSC) the PRP group responsible for implementing the
remedial action at the Hassayampa Landfill Site.
To date, the work at the Hassayampa Site has successfully controlled any off-Site, downgradient migration of Site-related
constituents. The remedy at the Hassayampa Site has been operated and maintained in a manner that has been and remains
protective of human health and the environment. In 2006, the HSC re-started and has operated almost continuously a portion
of the SVE system to control, at a minimum, VOCs in the vadose zone soil gas. The work performed over the last 15-years to
optimize the SVE and groundwater recovery system (GRS) remedy components at the Hassayampa site will be detailed later.
Over 110-tons of VOCs have been removed from the Site and sent off-Site for disposal. The HSC maintains very good
relationships with its few Site neighbors.
2) Is the remedy functioning as expected? How well is the remedy performing?
The remedy is functioning as designed and as expected and is protective of human health and the environment. During the last
5-years, no problems have been encountered at the Site that would require any changes to the remedial design. The GRS and
SVE remedy components combined with security fencing and patrols, the flexible membrane liner cap and an extensive robust
soil vapor and groundwater monitoring program have insured that the remedy at the Hassayampa Site remains protective of
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
55
-------
human health and the environment.
3) What does the monitoring data show? Is contaminant containment occurring?
Contaminant containment is occurring. When operation of the SVE system ceased in 1998, the soil vapor monitoring data for
the vadose zone above the basalt layer beneath the Hassayampa Site indicated an upward trend on soil gas VOC
concentrations in the vicinity of the Put 1 area of the Hassayampa Site. Largely based on these data, a portion of the SVE
system was restarted in March 2006. The restarted SVE system has more than adequately controlled VOCs in the vadose zone
soil gas and has contributed to a reduction in VOC concentrations in portions of the Site groundwater.
The monitoring data indicates that the concentrations of VOCs in groundwater within the upper aquifer (Unit A) located just
beneath the basalt layer have been trending downward in a number of monitoring and groundwater recovery wells within the
capture zone of the groundwater pump and treat system; VOC concentrations at the monitoring points down-gradient of the
capture zone of the groundwater pump and treat system have remained non-detect. These decreasing data trends in the Unit A
aquifer are believed to be primarily, a function of the decreased VOC concentrations in the overlying vadose zone as a result
of the HSC's resumption of aggressive SVE operations.
The monitoring data indicates that the groundwater quality of the lower aquifer (Unit B) located just beneath Unit A has been
and remains unaffected by Site-related constituents both within the capture zone of the groundwater pump and treat system
and at all monitoring points downgradient of the capture zone of the groundwater pump and treat system. To date, VOCs have
not been detected above Performance Standards in groundwater samples collected from the lower (Unit B) aquifer.
No new chemicals of concern (COCs) have been identified in soil, soil gas or groundwater.
4) Please describe the frequency of site inspections and maintenance visit activities in the last five years.
The Hassayampa site does not have personnel on-Site continuously performing O&M. All of the SVE and GRS operations are
automated and equipped with sensors and shutoff interlocks to deal with any upset conditions and are linked to telemetry to
notify the appropriate O&M contractor in event of any upset conditions. I manage the overall operation and maintenance of
the remedy at the Hassayampa Site as well as the ongoing work to review and evaluate the current conceptual model for the
Site. As a result, I am responsible to ensure that routine site inspections are preformed, routine and non-routine maintenance
items are performed, the Site is maintained in an operational status; and the routine quarterly and annual reports are filed with
both EPA and ADEQ. As necessary, I visit the site to personally observe operational and investigative work. I meet
approximately semi-annually, at a minimum, with EPA and ADEQ personnel and contractors face-to-face to provide updates
of ongoing work at the Site, review plans for upcoming work and to review and discuss the results of every sampling event. I
have had conference calls and net-meetings with EPA and ADEQ personnel to provide frequent telephone conversations and
correspond via e-mail and letters with EPA and ADEQ personnel and contractors to provide updates of on-going work at the
Site, work on 5-year review issues, review plans for upcoming work and to review and discuss the results of every sampling
event.
Over the past 5 years the HSC's contractors conduct: monthly site inspections in addition to responding to any alarm
conditions from the groundwater pump & treat system and bi-weekly inspection of the SVE system; quarterly groundwater
and soil vapor sampling; and other Site-related inspection, maintenance and monitoring activities on an as needed basis. All of
the data from these visits and inspections are conveyed to EPA in the routine semi-annual reports or, if needed, separate
incident reports.
As needed, I have responded, via telephone conversations, correspondence and in-person meetings, to inquiries from actual
Site neighbors (e.g., Hickman's Family Farms and inquiries from individuals contemplating purchasing property in the
vicinity of the Site). When asked, the HSC has shared its knowledge of the local and regional hydrogeology and its
groundwater water level and water quality data bases with its neighbors.
5) Have there been any significant changes in the Operations & Maintenance requirements, maintenance schedules, or sampling
routines in the last five years? If so, do they affect protectiveness of the remedy? Please describe changes and impacts.
Except for SVE system rebound testing and a groundwater recovery test in 2020, there have not been any significant changes
in the O&M requirements or maintenance schedules in the last five years. Sampling routines still include additional analyses
for nitrates and 1,4-dioxane as requested by EPA, the addition of several wells, and reductions in sampling frequencies at a
number of soil vapor and groundwater points based upon statistical evaluations of trends as reported in the 2020 Annual
Report. If anything, there has been an increase in the protectiveness of the remedy given the mass of VOCs removed from the
source area.
6) Have there been unexpected Operations & Maintenance difficulties or costs at the site in the last five years? If so, please give
details.
While the Site has experienced routine O&M mechanical issues, there have not been any unexpected O&M difficulties at the
site in the last 5-years.
7) Have there been opportunities to optimize Operations & Maintenance or sampling efforts? Please describe changes and resultant
or desired cost savings or improved efficiency.
The efficiency and up-time of the groundwater pump and treat system have improved and the need for call-out response to
alarm or upset conditions has decreased.
56
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
The HSC has been working with EPA and ADEQ to maximize, to the extent practical, applicability of efficacy of alternate
groundwater sample acquisition techniques, such as passive diffusion bags. As a result, sampling efficiency and, therefore,
cost efficiencies to obtain groundwater samples have improved. Hie HSC believes that over time this will result in more
consistent groundwater data.
On the soil vapor side, since March 2006 the HSC has successfully re-started and operated portions of the SVE system using
the GEO cryogenic off-gas treatment system. In August 2015, a full-scale pilot test of an air phase granulated activated carbon
off gas treatment system was successfully implemented and, as a result, installation of a permanent air phase granular
activated carbon off gas treatment system was completed.
8) Are you aware of any changes in Federal/State/County/Local laws and regulations that may impact the protectiveness of the
remedy?
No.
9) Are you aware of any changes in the nearby land use in the last five years?
Hickman's Family Farms has increased to size of its egg production facility and added a waste drying facility and a new deep
groundwater well. There have been no other land use changes.
10) Are you aware of any vandalism at the site in the last five years?
As a result of the HSC's combination of well-maintained security fencing and nightly patrols there has been no vandalism at
the site in the last five years.
11) Do you have any comments, suggestions, or recommendations regarding the project?
The project is on track with the remedy proceeding as anticipated. There has been no tiling in the data collected over the lasts
5-years to indicate DNAPL in contact with groundwater or the presences pf significant DNAPL concentrations in the vadose
zone near the groundwater table. The HSC has, at EPA's request, examined a number of methods that were posed as possibly
optimizing or accelerating clean-up (i.e., more aggressive source area treatments) but none have been practical or cost
effective. MW-21UB was added to the groundwater monitoring network to improve the long-term verification of conditions in
Unit B and serve as a background well for nitrate. MW-21UB and its paired well MW-21UAR serve to document capture and
verify that there is no downward migration of site-related contamination in that area. The data from MW-21UB and all of the
other nitrate data collected by the HS when combined with all of the available regional nitrate data solidly confirm that any
nitrate in the treated water going to the injection well has no potential to impact public health. The CSM, O&M Plan and the
QAPP are updated, the SVPSs have been revised and the updated performance monitoring requirements have been redesigned
to take into consideration and effects soil vapor will have on meeting site closure requirements and the remote possibility that
any residual, non-mobile DNAPL might have an effect on meeting Site closure requirements.
Additional Site-Specific Questions
None
Five-Year Review Interview Record
Site:
Hassayampa Landfill
EPA ID No: AZD980735666
Interview Type: Filling-in Interview Record
Location of Visit: N/A
Date: February 10, 2021
Time: N/A
Interviewers
Name
Title
Organization
Interviewees
Name
Organization
Title
Telephone
Email
Jeff Menken
Hargis + Associates. Inc.
Senior Hydrogeologist
Summary of Conversation
1) What is your overall impression of the project?
My overall impression is that the project is successful. Off-Site, down-gradient migration of Site-related constituents has been
prevented, the vertical migration potential of contaminants in groundwater is low, and the remedy at the Site has been
operated and maintained in a manner that has been and remains protective of human health and the environment. The soil
vapor system has been successful in decreasing soil vapor concentrations to below the Soil Vapor Performance Standards
(SVPSs) during operation and has been undergoing a series of rebound tests to evaluate how much longer it will continue to
be needed. Groundwater concentrations are decreasing in all wells except those located between the source area (Pit 1) and the
extraction wells.
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
57
-------
2) Is the remedy functioning as expected? How well is the remedy performing?
The remedy is performing as expected, all affected groundwater is captured, and soil vapor concentrations have been reduced
to below SVPSs during SVE operation. Soil vapor rebound testing to-date has resulted in slow, minimal increases of soil
vapor concentrations and testing completed in 2019/2020 indicated soil vapor concentrations remained below SVPSs for 9
months without SVE operation. A 2019 groundwater recovery test that allowed re-saturation of the vadose zone identified no
groundwater concentration increases resulting from re-saturation. This is in sharp contrast to the 200% to 500% groundwater
concentration increases documented when Pit 1 area vadose zone soils were re-saturated as part of SVE operations between
2007 and 2012. The 2019 results, along with low soil vapor concentrations in sub-basalt soil vapor monitoring wells, indicate
the soil vapor extraction system has significantly reduced the Pit 1 vadose zone residual mass. As a result, groundwater
concentrations inMW-18UA (north of Pit 1) are decreasing as are those across the Site except for in wells between Pit 1 and
the extraction wells.
3) What does the monitoring data show? Is contaminant containment occurring?
The monitoring data indicate that containment of affected groundwater has been maintained. Data also indicate that soil vapor
concentrations are now de-minimis and groundwater concentrations are declining apart from the areas between Pit 1 and the
extraction wells. This is to be expected as the plume migrates towards the pumping wells. Unit B groundwater remains
unaffected by VOCs.
No new chemicals of concern (COCs) have been identified in soil, soil gas or groundwater. Nitrate is routinely detected in
groundwater samples above the EPA MCL, however nitrate concentrations in both Unit A and Unit B groundwater samples
have been proven to have historically been below background concentrations of this chemical and for that reason nitrate is not
considered a site-related contaminant. Similarly, total chromium has occasionally been reported above the groundwater
performance standards (GWPSs) in upgradient Unit A monitor well MW-11UA. These have also been shown to be related to
background conditions. Additional analyses for 1,4-dioxane have also been performed. 1,4-dioxane has only been detected in
groundwater samples at Pit 1 area wells (MW-18UA and MW-19UA) at very low concentrations that attenuate before they
reach downgradient wells. Since this compound would be expected to be at significantly higher concentrations if it were
present in groundwater (based on concentrations of other VOCs) and at other sample locations, it is not considered to be a
significant contaminant in Site groundwater.
4) Please describe the frequency of site inspections and maintenance visit activities in the last five years.
The Hassayampa Site is remote, and no continuous O&M presence is maintained. Instead, SVE and GRS operations are
remotely monitored with systems that automatically communicate alarm conditions. Hargis performs monthly Site inspections
and O&M on Site components per the schedule approved in the O&M manual. Monthly inspections include cap condition,
security, well conditions, GRS operation/condition, etc. More thorough inspections are completed by Hargis annually,
including teardown and cleaning of the GRS. Hargis also conducts quarterly groundwater sampling.
During operation, photoionization detector and vacuum readings are collected for the SVE system on a weekly basis by either
Hargis or Geosyntec. Other O&M activities are performed as needed. The systems typically maintain an operational up-time
of greater than 95%.
5) Have there been any significant changes in the Operations & Maintenance requirements, maintenance schedules, or sampling
routines in the last five years? If so, do they affect protectiveness of the remedy? Please describe changes and impacts.
No significant changes to the GRS or Site O&M have occurred over the last 5 years. The O&M requirements for the SVE
system are dependent upon operation as it is occasionally off for rebound testing. Sampling routines have been adjusted
occasionally either in response to agency requests or following agency discussions and approval.
6) Have there been unexpected Operations & Maintenance difficulties or costs at the site in the last five years? If so, please give
details.
No O&M difficulties have been encountered in the last 5 years that significantly impacted the Site remedy. While the Site has
experienced routine O&M mechanical issues (e.g., power outages, pump failures, etc.) such issues are accounted for in annual
planning and strategies are in place to address them quickly and minimize downtime in the event they occur.
7) Have there been opportunities to optimize Operations & Maintenance or sampling efforts? Please describe changes and resultant
or desired cost savings or improved efficiency.
Optimization of the systems is an ongoing process that is formally addressed in each Annual Report. Over the last 5 years
several O&M changes have been performed to increase work efficiency such as installing a more rugged pitot tube and a
lighter GRS exhaust stack, but no major changes have been made to the GRS.
The cryogenic SVE treatment system was replaced in 2016 by a vapor phases granular activated carbon SVE system which
has operated since. This system has proven effective at treating soil vapor concentrations at a lower cost.
Sampling efforts are reviewed at least annually to identify opportunities to increase efficiency and several changes to the lists
of wells monitored and monitoring frequencies have been made, including those associated with the revised Performance
Monitoring and Verification Plan approved in 2017. No additional changes have been requested recently.
8) Are you aware of any changes in Federal/State/County/Local laws and regulations that may impact the protectiveness of the
remedy?
No.
9) Are you aware of any changes in the nearby land use in the last five years?
58
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
I am not aware of any land use changes since 2015 other than some expansion to Hickman's Egg Ranch operations northwest
of the Site at Baseline Road and 331st Avenue.
10) Are you aware of any vandalism at the site in the last five years?
No. The only significant unexpected damage to the Site in the last 5 years has been due to weather-related causes (for example
loss of a storage shed due to high winds) and did not significantly impact the remedy.
11) Do you have any comments, suggestions, or recommendations regarding the project?
Based on site data the project appears to be on track and is progressing as expected. Recent recommendations have included
potential additional SVE rebound testing. No additional recommendations have been made or are pending at this time.
Additional Site-Specific Questions
None
Five-Year Review Interview Record
Site:
Hassayampa Landfill
EPA ID No: AZD980735666
Interview Type: Filling-in Interview Record
Location of Visit: N/A
Date: February 23, 2021
Time: N/A
Interviewers
Name
Title
Organization
Interviewees
Name
Organization
Title
T elephone
Email
Michael Reardon
Geosyntec
Project Manager
Summary of Conversation
1) What is your overall impression of the project?
I have been working on the project since Geosyntec's initial involvement in 2005. In 2006 the SVE system was restarted and
was aggressively operated targeting areas of the Site with the highest concentrations of VOCs, resulting in removal of over
110-tons of mass to date. Since the development and Agency approval of the soil vapor performance standards (SVPSs), three
rounds of rebound testing of SVE system has been conducted indicating that permanent shut down of the SVE remedy may be
possible in the near future. The aggressive mass removal efforts will serve to maintain protectiveness over the long term. In
the same time frame the groundwater recovery system (GRS) has also been relatively continuously operated providing
containment of VOCs in groundwater with some additional mass removal.
The HSC has also worked closely with the Agencies over the last 15 years to address questions or concerns that have arisen.
The HSC has more recently worked with the Agencies to finalize performance standards and operational protocols contained
in the performance monitoring and verification plan (PMVP) to guide later operation and eventual shutdown of the SVE and
GRS remedies. In summary, site conditions are understood, the remedies are operating as intended and plans have been
developed and approved to guide future operation of the SVE and GRS systems.
2) Is the remedy functioning as expected? How well is the remedy performing?
Both the GRS and SVE remedies are functioning as designed and expected. Capture of VOC affected groundwater has been
maintained by the GRS. The operational configuration of the SVE system has also been transitioned to carbon for off-gas
treatment due to the declining influent concentrations and mass removal rates that were experienced in 2015. Since initially
achieving soil vapor performance standards (SVPSs) which supported conducting rebound testing, the operation of the carbon
based SVE system is currently being focused on controlling concentration rebound in the Pit 1 area. Previous Agency
questions regarding capture of VOC affected groundwater along the eastern side of the Site as well as potential vertical
migration to Unit B have also been addressed.
3) What does the monitoring data show? Is contaminant containment occurring?
Groundwater and soil vapor conditions are frequently monitored to demonstrate contaminant containment and steady progress
towards remedial goals. Through operation of the SVE system, soil vapor data have exhibited significant declines, where the
magnitude and extent of VOCs in soil vapor have been dramatically reduced in comparison to conditions in 2006 when SVE
was restarted. Per the Agency approved PMVP, soil vapor VOC concentrations in the Pit 1 source area have been reduced to
levels that support rebound testing and possible shutdown. Reductions in soil vapor VOC concentrations have resulted in
commensurate declines in influent VOC concentrations to GRS. These data trends continue to support the Conceptual Site
Model (CSM) for the Site that was jointly prepared with the Agencies. Earlier Agency questions with respect to contaminant
of VOC affected groundwater were addressed with the replacement of monitoring well MW-21UA and installation of MW-
21UB. The underlying Unit B groundwater continues to be regularly monitored.
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
59
-------
4) Please describe the frequency of site inspections and maintenance visit activities in the last five years.
Hie Hassayampa Site does not have personnel on-Site continuously performing O&M. The SVE and GRS operations are
automated and equipped with sensors and preprogramed shutdown thresholds. Systems also include telemetry to notify the
appropriate O&M contractor in event of any upset condition so that timely corrective measures can be implemented. Over the
last 5 years, the contractors have met approximately semi-annually which typically include site visits by project managers to
evaluate site and system conditions. Semi-annual meetings with EPA and ADEQ personnel and contractors have also been
held to provide updates of on-going work at the Site, review plans for upcoming work and to review and discuss the results of
sampling events. Conference calls and net-meetings with EPA and ADEQ personnel are also held as needed or requested to
provide updates of on-going work at the Site, resolve questions and review plans for upcoming work.
Over the past 5 years, groundwater related site activities have included monthly inspections in addition to responding to any
alarm conditions from the GRS and quarterly groundwater monitoring activities. Beginning in 2016, the full-scale granular
activated carbon (GAC) system was initiated for extraction and off-gas treatment of VOCs in soil vapor. The switch to the
GAC SVE system included some changes in the O&M performed for the SVE system. Soil vapor monitoring is also
performed semi-annually following an approximately 1-week shutdown of the SVE system (non-extracting conditions). Per
the Agency approved PMVP, rebound testing of the SVE system was also initiated in 2017 and three rounds of rebound
testing have been completed to date. All of the data from O&M visits, inspections and sampling events are submitted to
Agencies in the routine semi-annual and annual reports for the Site.
5) Have there been any significant changes in the Operations & Maintenance requirements, maintenance schedules, or sampling
routines in the last five years? If so, do they affect protectiveness of the remedy? Please describe changes and impacts.
Except for SVE system rebound testing initiated in 2017 and a groundwater recovery test in 2020, there have not been any
significant changes in the O&M requirements or maintenance schedules in the last 5 years. The groundwater sampling
program still includes additional analyses for nitrates and 1,4-dioxane as requested by EPA. Reductions in sampling
frequencies at a number of soil vapor and groundwater points based upon statistical evaluations of trends as reported in the
2020 Annual Report have been implemented with approval of the Agencies. The significant mass removal from the vadose
zone of over 110-tons has resulted in a commensurate decline in influent VOC mass to the GRS which results in an increase in
the protectiveness over the long term.
6) Have there been unexpected Operations & Maintenance difficulties or costs at the site in the last five years? If so, please give
details.
There have not been any unexpected difficulties with O&M of the systems that could not be addressed with replacement parts
or repairs to elements such as pumps, level controls, belts, etc.
7) Have there been opportunities to optimize Operations & Maintenance or sampling efforts? Please describe changes and resultant
or desired cost savings or improved efficiency.
Due to declining influent concentrations, a full-scale pilot test of an air phase granulated activated carbon off gas treatment
system was successfully implemented in 2015 and was made full scale in 2016. As a result, operating costs, including energy
costs have been reduced due to a change from the cryogenic treatment system and carbon consumption has steadily declined.
8) Are you aware of any changes in Federal/State/County/Local laws and regulations that may impact the protectiveness of the
remedy?
No.
9) Are you aware of any changes in the nearby land use in the last five years?
Hickman's Family Farms expanded its egg production facility and added a waste drying facility to produce fertilizer for
nearby farms and a new deep groundwater well. There have been no other significant land use changes since the last 5-yr.
review.
10) Are you aware of any vandalism at the site in the last five years?
As a result of the HSC's combination of well-maintained security fencing and nightly patrols there has been no vandalism at
the site in the last five years.
11) Do you have any comments, suggestions, or recommendations regarding the project?
Both the SVE and GRS remedies are operating as designed. The SVE system has been highly effective at removing VOC
mass from the vadose zone and has been showing signs of asymptotic mass removal. This condition is supported by initially
achieving SVPSs in 2017 which supported rebound testing of the SVE system. As of the 2020 Annual report, a third rebound
test of the SVE has been completed, where rebound sampling data supported shutdown of the SVE system for 9-months. The
focus on rebound testing should be maintained to support eventual shutdown of the active SVE remedy, which will save costs
and reduce energy consumption. The SVPSs which are used to guide rebound testing were developed to be protective of
groundwater at the Site. The GRS has been consistently operated throughout the 5-yr. review period, resulting in containment
of VOC affected groundwater and some mass removal. Efforts should continue to maintain consistent GRS operation and
containment of VOCs in groundwater per the PMVP.
Additional Site-Specific Questions
None
Five-Year Review Interview Record
60
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Site:
Hassayampa Landfill
EPA ID No:
AZD980735666
Interview Type: Filling-in Interview Record
Location of Visit: N/A
Date: March 2, 2021
Time: N/A
Interviewers
Name
Title
Organization
Interviewees
Name
Organization
Title
T elephone
Email
Karin Harker
ADEQ
Unit Manager (former Project Manager)
Summary of Conversation
1) What is your overall impression of the project?
The project is progressing as expected. Any issues that arise are communicated and addressed in a timely manner.
2) Is the remedy functioning as expected? How well is the remedy performing?
The remedy is functioning and performing as expected.
3) What does the monitoring data show? Is contaminant containment occurring?
Impacts to groundwater are limited to a few onsite wells and the vapor concentrations are below the Soil Vapor Performance
Standards (SVPS). The SVE system was shut down during rebound testing and restarted after several months of monitoring
due to increasing concentrations for several contaminates of concern.
4) Please describe the frequency of site inspections and maintenance visit activities in the last five years.
Site was transferred early 2019 for a limited period during my role as the ADEQ Project Manager. During that time there was
no visit activities performed. However, ADEQ did performed one site visit in the new role as Unit Manager with the newly
assigned Project Manager in May 2020. The frequency of site inspections and maintenance visit activities for ADEQ has been
limited over the last five years but appears regularly frequent for the Hassayampa Steering Committee and consultants.
5) Have there been any significant changes hi the Operations & Maintenance requirements, maintenance schedules, or sampling
routines in the last five years? If so, do they affect protectiveness of the remedy? Please describe changes and impacts.
Equipment malfunctions occasionally occur and result in system shutdowns. The contractor is timely in their responsiveness
to the equipment failure minimizing the shutdown times and ensuring the protectiveness of the remedy.
6) Have there been unexpected Operations & Maintenance difficulties or costs at the site hi the last five years? If so, please give
details.
Periodic power outages at the site have cause system shutdowns. However, the contractor responded to the outages, restarted
the system, and communicated issues in a timely manner. The age of the system has resulted in increased equipment
malfunctions causing system shutdowns. The contractor is very responsive to repairing and restarting the system in a timely
manner.
7) Have there been opportunities to optimize Operations & Maintenance or sampling efforts? Please describe changes and resultant
or desired cost savings or unproved efficiency.
Yes, rebound testing occurred on the SVE system. However, after several months of monitoring during the rebound test period
several VOC concentrations increased to SVPS. These increases lead to the decision to restart the system and perform rebound
testing again at a future date.
8) Are you aware of any changes in Federal/State/County/Local laws and regulations that may impact the protectiveness of the
remedy?
Not to my knowledge
9) Are you aware of any changes in the nearby land use in the last five years?
Not to my knowledge
10) Are you aware of any vandalism at the site in the last five years?
Not to my knowledge
11) Do you have any comments, suggestions, or recommendations regarding the project?
The remediation systems are kept in good working condition due to routine and regular maintenance. However, the age of the
system does have the potential to increase maintenance costs, as made evident by the reported equipment failures and
malfunctions. Within the next 5 years Groundwater Remediation System equipment nearing end of life should be replaced and
rebound testing of the SVE system should be reattempted.
Concerning the power outages, countermeasures should be discussed to reduce the frequency, especially during the summer
monsoon season.
Additional Site-Specific Questions
None
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
61
-------
Five-Year Review Interview Record
Site:
Hassayampa Landfill
EPA ID No: AZD980735666
Interview Type: Filling-in Interview Record
Location of Visit: N/A
Date: March 3, 2021
Time: N/A
Interviewers
Name
Title
Organization
Interviewees
Name
Organization
Title
T elephone
Email
Brett McDaniel
ADEQ
Former Project Manager
Summary of Conversation
1) What Is your overall impression of the project?
Hie project is progressing as expected. Communication among all parties is ongoing and beneficial. The RP is actively and
aggressively seeking the most effective and efficient remedy solutions for the site.
2) Is the remedy functioning as expected? How well is the remedy performing?
The remedy is functioning and performing as expected. Groundwater and vapor plumes are contained and decreasing in size.
3) What does the monitoring data show? Is contaminant containment occurring?
Impacts to groundwater are limited to a few onsite wells and the vapor concentrations are below the Soil Vapor Performance
Standards (SVPS). The SVE system was shut down for rebound testing and promptly restarted after several months of
monitoring due to increasing concentrations for several contaminates of concern. Based on these results, it appears that several
iterations of SVE system shutdown and restart are necessary.
4) Please describe the frequency of site inspections and maintenance visit activities in the last five years.
The RP has efficiently performed site visits for maintenance. Any unexpected maintenance or repairs are promptly remedied.
Shortly after my onset as Project Manager, ADEQ staff performed one site visit in October 2018. Remedial equipment and
monitoring assets appeared in good condition.
5) Have there been any significant changes in the Operations & Maintenance requirements, maintenance schedules, or sampling
routines in the last five years? If so, do they affect protectiveness of the remedy? Please describe changes and impacts.
Operation of the remedial system was (rebound) tested for transitioned from full-time to periodic operation to allow for
rebound and more efficient recovery of COCs. Results suggested fairly rapid rebound and system returned to full-time
operation. Equipment malfunctions occasionally occur and result in system shutdowns. The contractor is timely in their
responsiveness to the equipment failure minimizing the shutdown times and ensuring the protectiveness of the remedy.
6) Have there been unexpected Operations & Maintenance difficulties or costs at the site in the last five years? If so, please give
details.
Periodic power outages at the site have cause system shutdowns. However, the contractor responded to the outages, restarted
the system, and communicated issues in a timely manner. The age of the system has resulted in increased equipment
malfunctions causing system shutdowns. The contractor is very responsive to repairing and restarting the system in a timely
manner.
7) Have there been opportunities to optimize Operations & Maintenance or sampling efforts? Please describe changes and resultant
or desired cost savings or improved efficiency.
Yes, rebound testing occurred on the SVE system. However, after several months of monitoring during the rebound test period
several VOC concentrations increased to SVPS. These increases lead to the decision to restart the system and perform rebound
testing again at a future date.
8) Are you aware of any changes in Federal/State/County/Local laws and regulations that may impact the protectiveness of the
remedy?
No.
9) Are you aware of any changes in the nearby land use in the last five years?
No.
10) Are you aware of any vandalism at the site in the last five years?
No.
11) Do you have any comments, suggestions, or recommendations regarding the project?
The remediation systems are kept in good working condition due to routine and regular maintenance. However, the age of the
system does have the potential to increase maintenance costs, as made evident by the reported equipment failures and
malfunctions. Within the next 5 years Groundwater Remediation System equipment nearing end of life should be replaced and
rebound testing of the SVE system should be reattempted.
Concerning the power outages, countermeasures should be discussed to reduce the frequency, especially during the summer
monsoon season.
62
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
System equipment tolerances should be evaluated for increases in summertime temperatures. Equipment upgrades or cooling
mechanisms may be needed to safeguard equipment and visiting personnel within the next 5 years.
Additional Site-Specific Questions
None
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site 63
-------
Appendix H: Site Inspection Report and
Photos
Hassayampa Landfill
a. Date of Visit: 13 July 2021
b. Location: 40 miles west of Phoenix, AZ
c. Purpose: A site visit was conducted to visually inspect and document the conditions of the
remedy, the site, and the surrounding area for inclusion into the Five-Year Review Report.
d. Participants:
Matthew Masten US Army Corps of Engineers, Env. Engineer 602-230-6873
Jim Davis Senior Project Manager, Hargis + Associates 520-727-7130
Mike Hall Lead Field Tech, Hargis + Associates
Daniel Hall Field Tech, Hargis + Associates
Branden Selleh Field Tech, Hargis + Associates
Natalie Romanoff Project Manager, ADEQ 602-771-0956
A site visit to the Hassayampa Landfill Superfund Site was conducted on 13 July 2021. The
inspection included visual observation of overall site conditions and inspection of various components of
the remedy. The participants received an overview of the site and the remedial history. The inspection
evaluated the landfill cap, the groundwater treatment system, soil vapor extraction system, groundwater
and gas extraction wells.
On 13 July 2021, Mr. Masten arrived at the Hassayampa Landfill Superfund Site at 0700 hrs. The
weather was partly cloudy, calm, and approximately 90 degrees Fahrenheit. The participants first toured
the groundwater treatment system located in the on-site building. Since the previous Five-Year Review,
an effluent check valve was replaced on the groundwater treatment system, the air stripper tray sight glass
is now clear PVC and the data logger has been replaced. Mr. Mike Hall indicated that the air blower
motor is scheduled to be replaced in October 2021. Mr. Hall confirmed that the aerator trays are being
manually descaled yearly. The O&M manual and Health and Safety plans were all in place. No other
64
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
major changes or issues with the air stripper were noted; the system appears to be in good condition and
functioning normally.
Mr. Hall indicated that his team is focusing on housekeeping throughout the site and plans on disposing
of miscellaneous unneeded/discarded equipment and supplies. Mr. Hall noted that a rattlesnake was
discovered inside the system building the previous Saturday. He contacted personnel from the Palo Verde
Generating Station, who voluntarily came and relocated the snake. No rodent damage was noted in the
building. Mr. Hall confirmed that Orkin pest control regularly comes on site to maintain rodent traps. Mr.
Hall explained that Hargis personnel had trapped approximately 10 rodents near MW-2, and they have not
returned.
The team next inspected the Vapor Phase Granular Activated Carbon vessels for the SVE system. The
SVE system was not operating, as a rebound test was currently underway. The system is run by
Geosyntec, but Hargis and Associates has performed the environmental sampling. Mr. Hall noted that the
tubing for the GAC vessels has been replaced as necessary and painted to prevent sun damage. He stated
that the system has condensation issues in the wintertime and the lines must be drained as needed.
Geosyntec performs the maintenance on the system. Minor animal burrowing was noted in the berm that
surrounds the SVE control system, blower and condensation tank; no other issues were noted.
The team next walked the rest of the Hassayampa landfill site, inspecting the SVE above-ground piping,
source area wells, and the landfill cap itself. The piping was found to be in good condition. The unused
piping manifold noted in the previous Five-Year Review has been dismantled and removed.
Representative vapor and monitoring wells (V-l 1, MW-19UA, MW-6UA) were inspected. All wells were
found to be secured and in good shape. The landfill cap was noted to be in good shape overall. Vegetation
was sparse due to recent dry conditions. Minor erosion damage was noted down gradient from the main
gate. A low spot in the adjacent county road causes runoff to flow eastward across the site and also
towards county well MW-10A. This erosion damage did not appear to affect the protectiveness of the
remedy. Gravel has been spread in this area to help alleviate the erosion issue. This minor erosion appears
to be the only site maintenance issue. Mr. Hall said this is checked monthly, and there is an on-site
stockpile of gravel if more is needed to be placed.
The fence on the perimeter of the site was in good condition and is inspected monthly. No evidence of
vandalism was noticed; Mr. Hall said he was not aware of any trespassing issues. A security guard, shared
with the nearby Hickman Egg farm, patrols nightly.
Mr. Masten inspected extraction well vaults outside the fence line. The well vault settling issue at
extraction well EW-01UA, noted in the previous Five-Year Review, has been fixed. However, the well
vault for EW-02UA has a similar issue due to erosion and settling. The well vault lid will not completely
close. It was noted that these wells were not currently in use. All other wells and vaults appeared to be in
good condition.
Mr. Hall explained that the site has occasional phone line communication issues during stormy weather.
This affects the data logger for the ground water treatment system. When this occurs, he is notified, and
Century Link (the local phone company) will repair the issue.
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
65
-------
The formerly used thermal oxidation system was noted to still be on site. Mr. Masten was informed that
there was no current plan to remove the system. Inquiries made to companies to scrap the equipment have
been unsuccessful. It is currently cost prohibitive to remove, manifest and properly dispose of the system.
The team met at the parking area and then proceeded to inspect the injection well west of the site. The
well vault was found to be secured and the well was in good working order. Mr. Masten departed the site
at 1100 hrs.
All components of the remedial action for the Hassayampa Landfill appear to be in good condition and
are currently operating as intended.
Matthew Masten, P.E.
Environmental Engineer
US Army Corps of Engineers, LA District
66
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Photo 9 - Air stripper system
Photo 10 - Extraction well flowrate gauges
Fifth Five-Year Review for the Hassayampa Landfill Superfund
67
-------
Photo 11 - Air stripper trays
68
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Photo 12- Clear PVC sight glass on air stripper trays
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
69
-------
Photo 13 - View of replaced effluent check valve (center right of photo)
70
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Photo 14 - View of VGAC vessels
Photo 15 - VGAC system, and condensation tank
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
71
-------
Photo 16 - View of SVE system above ground piping, facing east
Photo 17 - Site of former piping manifold, facing north
72
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
^4 >*!
Photo 18-Well V-ll
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
73
-------
Photo 19 - Well MW-19UA with hanging passive diffusion bag
74
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Photo 20 - Wei! MW-6UA
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
75
-------
Photo 21 - Extraction well EW-4UA
76
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Photo 22 - Extraction well EW-2UA, showing partially closed lid
•• -------V>
Photo 23 -Overview of site facing northwest, towards treatment system
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
77
-------
lllfi
Photo 24 - Entrance gate, facing southwest
78
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Photo 25- Gravel placed over minor erosion area, downgradient of main gate, facing east
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
79
-------
26- View towards main gate, facing west, showing minor erosion
80
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
27- Formerly used thermal oxidation system
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
81
-------
Photo 28- Secured doors to ground water treatment system building
82
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
-------
Photo 29- Injection well west of site
Fifth Five-Year Review for the Hassayampa Landfill Superfund Site
83
------- |