RECORD OF DECISION
DONNA RESERVOIR AND CANAL SYSTEM
SUPERFUND SITE
DONNA, HIDALGO COUNTY, TEXAS
EPA ID: TX0000605363
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PRO-^°
U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION 6
DALLAS, TEXAS
SEPTEMBER 2018
100011997
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TABLE OF CONTENTS
Page
APPENDICES ii
LIST OF TABLES ii
LIST OF FIGURES iii
LIST OF ACRONYMS AND ABBREVIATIONS v
PART 1: THE DECLARATION 1
1.1 Site Name and Location 1
1.2 Statement of Basis and Purpose 1
1.3 Assessment of the Site 1
1.4 Description of the Selected Remedy 1
1.5 Statutory Determinations 2
1.6 Data Certification Checklist 4
1.7 Authorizing Signature 5
CONCURRENCE PAGE FOR RECORD OF DECISION 6
PART 2: THE DECISION SUMMARY 7
2.1 Site Name, Location, and Brief Description 7
2.2 Site History and Enforcement Activities 8
2.3 Community Participation 15
2.4 Scope and Role of Response Action 16
2.5 Site Characteristics 17
2.6 Current and Potential Future Land and Resource Uses 24
2.7 Summary of Site Risks 25
2.8 Remedial Action Objectives 40
2.9 Description of Alternatives 44
2.10 Comparative Analysis of Alternatives 58
2.11 Principal Threat Wastes 67
2.12 Selected Remedy 68
2.13 Statutory Determinations 70
2.14 Documentation of Significant Changes 77
2.15 State Role 78
PART 3: RESPONSIVENESS SUMMARY 79
3.1 Stakeholder's Comments and EPA's Responses 79
REFERENCES 107
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APPENDICES
Appendix A Summary of Human Health Exposure Factors and Intake Equations
Appendix B Selection of Chemicals of Potential Concern for Exposure Areas
Appendix C Costs for Alternative 6, Replace Siphon and Dredging of Canal
Sediment with Off-Site Disposal
Appendix D Determination of Applicable or Relevant and Appropriate
Requirements and To-Be-Considered Criteria
LIST OF TABLES
Number Title
1 Measurement Endpoints for Ecological Risk Assessment
2 Threatened and Endangered Species that May Be Found in Hidalgo
County
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LIST OF FIGURES
Number Title
1 Site Location
2 Site Layout
3 Existing Siphon Plan, Profile, and Sections
4 Concentrations of Aroclor-1254 and Aroclor-1260 in Sediment in the Main
Canal and Rio Grande River
5 Concentrations of Total Polychlorinated Biphenyl Congeners in Sediment
in the Main Canal and Rio Grande River
6 Concentrations of Aroclor-1254 and Aroclor-1260 in Sediment and Soil in
the Arroyo Colorado River and Tributary
7 Concentrations of Total Polychlorinated Biphenyl Congeners in Sediment
and Soil in the Arroyo Colorado River and Tributary
8 Concentrations of Aroclor-1254 and Aroclor-1260 in Sediment and Soil in
the Lower West Main Canal Unlined South of the 90 Degree Bend
9 Concentrations of Total Polychlorinated Biphenyl Congeners in Sediment
and Soil in the Lower West Main Canal Unlined South of the 90 Degree
Bend
10 Concentrations of Aroclor-1254 and Aroclor-1260 in Sediment and Soil in
the Lower West Main Canal Unlined North of the 90 Degree Bend
11 Concentrations of Total Polychlorinated Biphenyl Congeners in Sediment
and Soil in the Lower West Main Canal Unlined North of the 90 Degree
Bend
12 Concentrations of Aroclor-1254 and Aroclor-1260 in Sediment and Soil in
the Lower East Main Canal
13 Concentrations of Total Polychlorinated Biphenyl Congeners in Sediment
and Soil in the Lower East Main Canal
14 Concentrations of Aroclor-1254 and Aroclor-1260 in Sediment in Reservoir
No. 3
15 Concentrations of Total Polychlorinated Biphenyl Congeners in Sediment
in Reservoir No. 3
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LIST OF FIGURES (CONTINUED)
Number Title
16 Concentrations of Aroclor-1254 and Aroclor-1260 in Sediment in the Cross
Over Main Canal and Water Treatment Plant
17 Concentrations of Total Polychlorinated Biphenyl Congeners in Sediment
in the Cross Over Main Canal and Water Treatment Plant
18 Fish Concentrations of Aroclor-1254, Aroclor-1260, and Total
Polychlorinated Biphenyl Congeners
19 Total Polychlorinated Biphenyl Congeners in Surface Water Samples
Collected from Inside the Siphon
20 Semi-Permeable Membrane Device Concentrations of Total
Polychlorinated Biphenyl Congeners
21 Polyoxymethylene Concentrations of Total Polychlorinated Biphenyl
Congeners
22 Human Health Conceptual Site Model, Donna Reservoir and Canal
System
23 Ecological Exposure Areas
24 Ecological Conceptual Site Model, Donna Reservoir and Canal System
25 Sediment Remediation Area Based on a Sediment Cleanup Goal of
0.043 mg/kg
26 Siphon Replacement
27 Pictorial Conceptual Site Model
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LIST OF ACRONYMS AND ABBREVIATIONS
95% UCL 95 percent upper confidence limit
|jg/kg microgram(s) per kilogram
ADI average daily intake
ARAR applicable or relevant and appropriate requirement
CERCLA Comprehensive Environmental Response, Compensation, and
Liability Act
CFR Code of Federal Regulations
cfs cubic feet per second
Cleanup Level CUL
COC chemical of concern
COPC chemical of potential concern
CWA Clean Water Act
DRCS Donna Reservoir and Canal System
EA EA Engineering, Science, and Technology, Inc., PBC
EPA U.S. Environmental Protection Agency
EPC Exposure Point Concentration
ERA Ecological Risk Assessment
Gl ABS gastrointestinal absorption factor
HHRA Human Health Risk Assessment
HI hazard index
HQ hazard quotient
IBWC International Boundary and Water Commission
IRIS Integrated Risk Information System
Irrigation District Donna Irrigation District Hidalgo County Number One
LRGVES Lower Rio Grande Valley Environmental Study
mg/kg milligram(s) per kilogram
mg/kg bw-day milligram(s) per kilogram body weight per day
mg/kg-day milligram(s) per kilogram per day
NCP National Oil and Hazardous Substances Pollution Contingency Plan
NPDES National Pollutant Discharge Elimination System
NPL National Priorities List
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LIST OF ACRONYMS AND ABBREVIATIONS (CONTINUED)
PCBs
polychlorinated biphenyls
pg/L
picogram(s) per liter
PPm
part(s) per million
PRPs
Potentially Responsible Parties
PRG
Preliminary Remediation Goal
PPRTV
Provisional Peer Reviewed Toxicity Value
RAO
Remedial Action Objective
RG
Remediation Goal
ROV
Remote-Operated Vehicle
RCRA
Resource Conservation and Recovery Act
RfD
reference dose
ROD
Record of Decision
SF
slope factor
SSI
Screening Site Inspection
Site
Donna Reservoir and Canal System Superfund Site
TCEQ
Texas Commission on Environmental Quality
TDSHS
Texas Department of State Health Services
TRRP
Texas Risk Reduction Program
TNRCC
Texas Natural Resource Conservation Commission
T&E
Threatened and Endangered
TBC
To-Be Considered
TSCA
Toxic Substances Control Act
USFWS
U.S. Fish and Wildlife Service
USGS
U.S. Geological Survey
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PART 1: THE DECLARATION
1.1 SITE NAME AND LOCATION
The Donna Reservoir and Canal System Superfund Site is located in Hidalgo County,
Texas. The U.S. Environmental Protection Agency's (EPA) Superfund Database
Identification Number for this Site is: TX0000605363.
1.2 STATEMENT OF BASIS AND PURPOSE
This Record of Decision (ROD) describes the "Selected Remedy" for the Donna
Reservoir and Canal System Superfund Site (hereinafter Site). The Selected Remedy
was chosen in accordance with the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980 (CERCLA), 42 U.S. Code §9601 et seq., as
amended by the Superfund Amendments and Reauthorization Act of 1986; and the
National Oil and Hazardous Substances Pollution Contingency Plan (NCP), 40 Code of
Federal Regulations (CFR) Part 300, as amended (EPA 1990). This decision is based
on the Administrative Record for the Site, which has been developed in accordance with
Section 133(k) of CERCLA, 42 U.S. Code §9613(k). The locations of the information
repositories and the Administrative Record file are presented in Section 2.3.3
(Information Repositories) of this ROD.
The State of Texas, represented by the Texas Commission on Environmental Quality
(TCEQ), was provided the opportunity to review and comment on the EPA's Selected
Remedy (i.e., Alternative 6 - Replace Siphon, Dredge Sediments, and Fish Removals).
1.3 ASSESSMENT OF THE SITE
The response action selected in this ROD is necessary to protect human health and the
environment from actual or threatened releases of hazardous substances into the
environment.
1.4 DESCRIPTION OF THE SELECTED REMEDY
The Selected Remedy is a final action for the Site. This Site is being addressed as a
single operable unit and all the areas and media of concern within the Site are
addressed in this ROD. The Selected Remedy addresses the Site-related human health
risks associated with consumption offish from the reservoir and canal system. It also
addresses Site-related risks to ecological receptors from contaminated sediment.
The Selected Remedy includes the following major components:
• Removal of approximately 20,000 cubic yards of sediment exceeding the
Cleanup Level of 0.043 milligrams/kilogram (mg/kg) Total Polychlorinated
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Biphenyls (PCBs), located in the canal approximately 4,500 feet downstream of
the Siphon's exit, and transportation to an off-site disposal facility;
• Replacement (i.e., construction of a new siphon) and abandonment of the
existing Siphon (i.e., grouting in place);
• Removal of fish annually for five years from all sections of the Site (additional fish
removals will be considered based on the attainment of the fish tissue
Remediation Goal);
• Post remediation Site monitoring that includes:
— Frequency offish tissue monitoring and sediment sampling of the canal
system will be determined during the remedial design of the Selected
Remedy;
• Implementation of a public outreach program for ten years to inform the
community of the potential health risks associated with consuming fish from the
Site;
• Installation and maintenance of signs at the Site for ten years to warn people of
the risks associated with consuming fish from the Site;
• Coordination with the Texas Department of State Health Services to maintain the
Aquatic Life Order Number 9 until the fish tissue concentrations have reached
the fish tissue Remediation Goal of 0.031 mg/kg Total PCBs;
• Implementation of an Institutional Control(s), in the form of a land-use restriction
or notice as to the environmental conditions of the property, which will protect the
integrity of the Selected Remedy, and evaluation of the appropriate Institutional
Control(s) in consultation with the TCEQ; and
• Performance of statutory Five-Year Reviews to evaluate the performance of the
Selected Remedy.
1.5 STATUTORY DETERMINATIONS
Pursuant to CERCLA Section 121 and the NCP; the EPA must select remedies that 1)
are protective of human health and the environment; 2) comply with applicable or
relevant and appropriate requirements (ARARs), unless a statutory waiver is justified; 3)
are cost-effective; 4) utilize permanent solutions and alternative treatment technologies
or resource recovery technologies to the maximum extent practicable; and 5) satisfy the
preference for treatment as a principal element of the remedy which permanently and
significantly reduces the toxicity, mobility, or volume of hazardous substances,
pollutants, or contaminants. The following section of this ROD discusses how the
Selected Remedy meets these statutory requirements:
1) Protection of Human Health and the Environment: The Selected Remedy will
protect human health and the environment by eliminating the contaminant
transport pathway from the likely source (i.e., the Siphon) into the environment.
The Selected Remedy will remove the sediment with the highest concentrations
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of PCBs, manage short-term human health risks while fish tissue concentrations
decrease with ICs, engineering controls, and a community involvement program.
Specifically, the exposure of recreational fishers to PCBs in fish tissue will be
reduced through the removal of contaminated sediment above the Cleanup Level
and the removal of the fish from the reservoir and canal system. Ecological
receptors of concern will be protected because they will no longer be exposed to
PCBs in sediment at levels that result in unacceptable risk. Protection of human
health and the environment is also discussed in Section 2.13.1 (Protection of
Human Health and the Environment) of this ROD.
2) Compliance with ARARs: The Selected Remedy will be in compliance with all
applicable ARARs. The NCP §§ 300.430(f)(5)(ii)(B) and (C) require that a ROD
describe the federal and state ARARs that the Selected Remedy will attain or
provide justification for any waivers. The implementation of the Selected Remedy
generally will not require federal, state, or local permits for on-site response
actions (40 CFR § 300.400[e][1]), but remedial actions must be completed in
conformance with the substantive technical requirements of applicable permit
regulations. ARARs for the Site are discussed further in Section 2.13.2
(Compliance with Applicable or Relevant and Appropriate Requirements) of this
ROD.
3) Cost Effectiveness: The Selected Remedy is cost-effective and represents a
reasonable value for the costs incurred. Section 300.430(f)(1 )(ii)(D) of the NCP
states that "A remedy shall be cost effective if its costs are proportional to its
overall effectiveness." The EPA evaluated the overall effectiveness of those
alternatives that satisfied the threshold criteria (i.e., protection of human health
and the environment and compliance with ARARs) by assessing three of the five
balancing criteria in combination (i.e., long-term effectiveness and permanence;
reduction in toxicity, mobility, and volume through treatment; and short-term
effectiveness). Overall effectiveness was then compared to costs to determine
cost-effectiveness. The overall effectiveness of this remedial alternative was
determined to be proportional to its costs and therefore the Selected Remedy
(i.e., Alternative 6) represents a reasonable value for the money to be spent. The
total estimated net present value cost to implement the Selected Remedy is
$19.4 million.
4) Utilization of Permanent Solutions and Alternative Treatment (or Resource
Recovery) Technologies to the Maximum Extent Practicable: The EPA has
determined that the Selected Remedy represents the maximum extent to which
permanent solutions and treatment technologies can be utilized in a practicable
manner at the Site. Of those alternatives that are protective of human health and
the environment and comply with ARARs, the EPA has determined that the
Selected Remedy provides the best balance of trade-offs in terms of the five
balancing criteria, while also considering the statutory preference for treatment
as a principal element and bias against off-site treatment and disposal and
considering State and community acceptance.
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5) Preference for Treatment as a Principal Element: The NCP establishes the
expectation that treatment will be used to address the principal threats posed by
a site whenever practicable (40 CFR 300.430[a][1][iii][A]). The "principal threat"
concept is applied to the characterization of "source materials" at a Superfund
site. A source material is material that includes or contains hazardous
substances, pollutants or contaminants that act as a reservoir for migration of
contamination to ground water, surface water or air, or acts as a source for direct
exposure. Principal threat wastes are those source materials considered to be
highly toxic or highly mobile that generally cannot be reliably contained, or would
present a significant risk to human health or the environment should exposure
occur.
The likely source material at the Site is the existing Siphon and the contaminated
sediment located downstream of the Siphon's exit. The Siphon and the
contaminated sediment are not highly toxic or highly mobile. The Selected
Remedy treats them as low-level threat waste and not principal threat waste.
Because the source material at the Site is not principal threat waste, and
because the ARARs do not require treatment, the Selected Remedy does not call
for treatment of the source material. Sections 2.11 (Principal Threat Wastes) and
2.13.5 (Preference for Treatment as a Principal Element) of this ROD describe
the results of the human health risk assessment and the chemical characteristics
of PCBs which indicate the Site's source materials' low toxicity and mobility,
respectively.
Because this remedy will result in hazardous substances remaining on the Site above
levels that allow for unlimited use and unrestricted exposure, a statutory review will be
conducted pursuant to CERCLA Section 121(c), 42 U.S.C. § 9621(a), and 40 CFR §
300.430(f)(4)(ii) within five years after initiation of the remedial action to ensure that the
remedy is, or will be, protective of human health and the environment.
1.6 DATA CERTIFICATION CHECKLIST
The following information is included in Part 2 (Decision Summary) of this ROD:
• Chemicals of concern (COCs) and their respective concentrations (Section 2.7.1
[Summary of the Human Health Risk Assessment]);
• Baseline risk represented by the COCs (Section 2.7 [Summary of Site Risks]);
• Remediation Goals, or Cleanup Levels, established for the COCs and the basis
for these levels (Sections 2.8 [Remedial Action Objectives], 2.8.1 [Human Health
Remediation Goal], and 2.8.2 [Ecological Preliminary Remediation Goal]);
• How there are no source materials constituting principal threats at the Site
(Sections 1.5 [Statutory Determinations], 2.10.2 [Balancing Criteria, 2.11
[Principal Threat Wastes], and 2.13.5 [Preference for Treatment as a Principal
Element]);
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• Current and reasonably anticipated land use assumptions arid current and
potential future beneficial uses of surface water used in the baseline risk
assessment and ROD (Sections 2.5.1 [Demographics and Cultural Features],
2.5.2 [Physical Characteristics], and 2.6 [Current and Potential Future Land and
Resource Uses]);
• Potential land and groundwater use that will be available at the Site as a result of
the Selected Remedy (Sections 2.5.1 [Demographics and Cultural Features],
2.5.2 [Physical Characteristics], and 2.6 [Current and Potential Future Land and
Resource Uses]);
• Estimated capital; annual operation and maintenance; and total present worth
costs, discount rate, and the number of years over which the remedy cost
estimates are projected (Section 2.9 [Description of Alternatives]); and
• Key factors that led to selecting the remedy (i.e., describe how the Selected
Remedy provides the best balance of tradeoffs with respect to the balancing and
modifying criteria, highlighting criteria key to the decision) (Sections 2.10
[Comparative Analysis of Alternatives] and 2.12.1 [Summary of the Rationale for
the Selected Remedy]).
Additional information can be found in the Administrative Record file for the Site. The
locations of the information repositories and the Administrative Record file are included
in Section 2.3.3 (Information Repositories) of this ROD.
1.7 AUTHORIZING SIGNATURE
This ROD documents the Selected Remedy for the Site. This remedy was selected by
the EPA after consultation with the TCEQ. The Director of the Superfund Division
(EPA, Region 6) has been delegated the authority to approve and sign this ROD.
By: - ^ ¦ Date:
Carl E. Edlund, P.E., Director
Superfund Division
U.S. Environmental Protection Agency, Region 6
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CONCURRENCE PAGE FOR RECORD OF DECISION
DONNA RESERVOIR AND CANAL SYSTEM SUPERFUND SITE
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PART 2: THE DECISION SUMMARY
This Decision Summary provides a description of the Site-specific factors and analyses
that led to the Selected Remedy. It includes background information, a summary of the
remedial investigation, the nature and extent of contamination, assessments of human
health and ecological risks posed by the contaminants at the Site, the basis for action,
and the identification and evaluation of remedial alternatives for the Site.
2.1 SITE NAME, LOCATION, AND BRIEF DESCRIPTION
The Donna Reservoir and Canal System Superfund Site (hereinafter Site) is located in
Hidalgo County, Texas (Figure 1 - Site Location), south of the City of Donna, near the
United States border with Mexico. The City of Alamo is located northwest of the Site.
The Site includes the approximately 400-acre Donna Reservoir (also known as Donna
Lake, Val Verde Lake, Laguna Val Verde, and Laguna El Gato), a system of lateral lined
and unlined canals and piping, and the Siphon. The Site extends north from the Rio
Grande River approximately 17 miles with lateral canals that extend approximately 5.6
miles to the east and west. The reservoir system, canals, and the Siphon are operated
by the Donna Irrigation District Hidalgo County Number One (hereinafter Irrigation
District), which provides drinking water to the City of Donna, drinking water to the North
Alamo Water Supply Corporation Plant No. 5, and irrigation water for the surrounding
predominantly agricultural land. According to a report by the Texas Natural Resource
and Conservation Commission (TNRCC), now the TCEQ, the remaining water that
enters the reservoir and canal system and is not diverted for drinking water or irrigation
purposes flows north of the Site into the Donna Drain and then east into the North
Floodway (Figure 1 - Site Location).
The Irrigation District pumps surface water into the Site from the Rio Grande River
through five pipes at a point approximately one mile downstream from Reynosa,
Tamaulipas, Mexico. The volume and velocity of the water entering the canal system
and eventually into the reservoirs can be controlled by the number of operational
pumps. The water enters the Donna Main Canal and travels north by gravity flow for
approximately two miles until it reaches the Siphon (Figure 2 - Site Layout). The Siphon
is a 1,600-foot-long nine-foot inner diameter concrete pipeline which runs underneath
the Arroyo Colorado River. After passing through the Siphon, water flow continues in an
unlined earthen canal before it reaches a concrete-lined channel that conveys water
north an additional 1.75 miles to the reservoir.
Donna Reservoir consists of a system of reservoirs that have an average depth of five
feet and stores up to 390 million gallons of water. The reservoir system is made up of
the East, West, and Northwest segments (Figure 2 - Site Layout). A lined canal flows
directly into the West Reservoir where water flows freely into the East Reservoir through
two conduits beneath South Valley View Road. This road divides the West and East
Reservoir segments.
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Sediment and fish found in the Donna Reservoir and the associated canals are
contaminated with Polychlorinated Biphenyls (PCBs). PCBs are a group of man-made
chlorinated hydrocarbons domestically manufactured from 1929 to 1979. The
manufacture of PCBs was discontinued in the U.S. in 1977 because of the compounds'
toxicity and persistence in the environment (EPA 2013). Aroclor is a trade name for a
specific group of PCBs (e.g., Aroclor-1254 and Aroclor-1260, among others) and each
Aroclor1 is a mixture of several PCB Congeners. Other trade names for PCBs exist. A
PCB Congener is any single unique chemical compound in the PCB category and there
are a total of 209 PCB Congeners. Total PCBs as Aroclors and PCB Congeners were
investigated at the Site. The highest concentrations of PCBs are found in the sediment
immediately downstream of the Siphon's exit (Figure 2 - Site Layout). PCBs were also
found in fish collected from all reaches of the system investigated. PCB Congeners
were detected in all surface water samples collected; however, PCB Aroclors were only
detected in one surface water sample which was collected near the Siphon's exit.
The likely source of PCB contamination at the Site has been determined to be the
Siphon, based on the data collected during the Remedial Investigation and the weight of
evidence. It is likely that the Siphon's construction/repair materials (e.g., concrete,
caulking, grout, or sealants) were a primary source of contamination at the Site. The
EPA could not locate specific records for the construction or the repair of the Siphon,
other than the information provided by the Irrigation District. This information indicates
that the Siphon was damaged by floodwaters in 1967, during Hurricane Beulah, and
may have been repaired. Samples of the Siphon's construction materials were not
collected by the EPA during the remedial investigation due to health and safety
concerns, technical challenges, and high cost. Additionally, all options considered for
the physical inspection of the interior of the Siphon introduced the potential to damage
the structural integrity of the Siphon. The Siphon was constructed in approximately 1926
and is probably approaching the end of its design life. It is possible that the concrete
and steel used to construct the Siphon may have degraded over time and any direct
physical efforts to sample the Siphon could damage the Siphon.
2.2 SITE HISTORY AND ENFORCEMENT ACTIVITIES
This section of the ROD provides background information on the construction of the
reservoir and canal system, federal and state investigations, and cleanup actions
conducted pursuant to CERCLA.
2.2.1 Donna Reservoir and Canal System Construction History
Construction of the canal system began in 1906 starting with the Rio Grande Pump
Station. This pump station was soon expanded to include a set of five diesel pump
engines that lift water through pipes from the Rio Grande River into the Main Canal
(Figure 2 - Site Layout). The Northwest Reservoir was placed into service in 1913 with
1 This document identifies PCB concentrations as PCBs measured as individual Aroclors (e.g., Aroclor-
1254, Aroclor-1260), as the sum of PCB Congeners (i.e., Total PCB Congeners), or as Total PCBs, which
is either the sum of PCB Aroclors or the sum of PCB Congeners.
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the construction of Re-Lift Pumping Plant No. 3 located on the northern side of the
reservoir system. The Siphon was constructed approximately in 1926 and replaced the
original elevated concrete canal that stretched above the Arroyo Colorado River on
concrete pillars. The West Reservoir of the reservoir system was placed into service in
1955 (TNRCC 2001).
A new section of the canal and the East Reservoir were constructed in 1963 through
1964. The new concrete-lined channel (i.e., Lower West Main Canal Lined) was
constructed east of the previous earthen canal that ran along the western boundary of
the Donna Irrigation District. Once the Lower West Main Canal Lined was placed into
service, the canal it replaced was abandoned and filled. The East Reservoir was
connected to the West Reservoir by conduits underneath South Valley View Road. The
Siphon was damaged by floodwaters in 1967, during Hurricane Beulah, and may have
been repaired.
The Irrigation District performs periodic maintenance of the earthen canals (i.e.,
dredging/excavation of sediment) as the need arises. Periodic maintenance includes
removal of soft sediment and material that accumulates on the bottom of the canals.
Material is mechanically removed from the canals and placed on the canal levee banks.
The Irrigation District performed maintenance in 1990 and 1991 at the Lower West Main
Canal Unlined from the Siphon's exit to the Lower West Main Canal Lined. Other
maintenance operations may have subsequently occurred as needed during the
operation of the reservoir and canal system. According to the Irrigation District,
additional maintenance of the reservoir and canal system may also be needed in the
future. This maintenance is required to maintain reservoir and canal capacity and flow.
2,2.2 Federal and State Investigations
A series of federal and state investigations and studies were performed by numerous
agencies throughout the Lower Rio Grande Valley prior to the start of the Remedial
Investigation and Feasibility Study by the EPA in September 2012. Additional
information regarding these investigations and studies can be found in the Remedial
Investigation Report (Revision 01) (EA Engineering, Science, and Technology, Inc.,
PBC [EA] 2016a). This section of the ROD provides a summary of these investigations
and studies.
Lower Rio Grande Valley Environmental Study of 1992
The Donna Irrigation District reservoir and canal system became an area of interest
during the implementation of the Lower Rio Grande Valley Environmental Study
(LRGVES) of 1992. The "Interagency Coordinating Committee for United States/Mexico
Border Environmental Health" initiated the LRGVES in response to the elevated rate of
infants born with neural tube defects in Cameron County in 1991. The study evaluated
contaminant exposure of nine families residing in Cameron and Hidalgo Counties
(TNRCC 1998). The study of one of the families revealed that the concentration of
PCBs in a common carp intended for human consumption was 399 parts per million
(ppm). This carp was reportedly caught in one of the main canals of the Donna Irrigation
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District reservoir and canal system. Blood samples from the residents in possession of
the fish also had elevated concentrations of PCBs (EPA 1994, TNRCC 2001).
The Texas Department of Health and the TNRCC conducted extensive sampling
throughout Hidalgo County and along the Rio Grande River from El Paso to Brownsville
following the results of the LRGVES. Elevated concentrations of PCBs in fish fillets
collected from the Donna Reservoirs, Donna Main Canal, and the Arroyo Colorado
River were found, while fish from other waters studied did not reveal elevated
concentrations (TNRCC 2001).
U.S. Geological Survey Suspended Sediment Evaluation
The U.S. Geological Survey (USGS) conducted suspended sediment sampling events
in the canal system between 1999 and 2001. The results of this investigation revealed
PCB-contaminated sediment and identified a 35-meter-long PCB concentration area of
the canal system just north of the Siphon's exit in the Lower West Main Canal Unlined,
on the right bank, as a possible source area (USGS 2002).
Texas Natural Resource Conservation Commission Screening Site
Inspection Report
The TNRCC's Superfund Site Discovery and Assessment Program, in coordination with
the EPA (Region 6), prepared a Screening Site Inspection (SSI) Report for the Site in
November 2001. The investigation included collecting samples, summarizing historical
Site data, and documenting observations of potential hazardous materials releases.
Analytical results from the SSI sampling events, conducted on April 9 through April 13,
2001, revealed elevated concentrations of PCB Aroclor-1254 in suspended sediment
samples. Concentrations ranged from 15.0 to 53.0 micrograms per kilogram (|jg/kg) in
suspended sediment over an approximate 5.75-mile distance within the Site. PCBs
were not detected in soil, surface water, or bed sediment samples collected during the
SSI. The SSI Report concluded that concentrations of the hazardous substance PCB
Aroclor-1254 met the observed release criteria and the source was listed as suspended
sediment (TNRCC 2001).
Texas Department of State Health Services Sampling and Visits to Restaurants
The results of the 2005 fish tissue collection by Texas Department of State and Health
Services (TDSHS) indicated that PCBs were present in most of the thirty fish collected
from the Main Canal, Lower West Main Canal Unlined, Lower West Main Canal Lined,
and Donna Reservoir at concentrations ranging from below detection limits (less than
0.005 |jg/kg) to 2,700 |jg/kg. The TDSHS concluded their 2005 report by stating that
"consumption of any of the . . . fish species from the DIS [Donna Irrigation System]. . .
continues to pose an apparent hazard to human health."
The EPA received information in March 2013 that a vendor was possibly selling fish
from Donna Lake to local restaurants. The EPA provided this information to the TDSHS
and, based on this information, the "Health Assessment and Toxicology Program" of the
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TDSHS visited approximately 60 restaurants in the Donna and Alamo, Texas, areas in
June 3 through 5, 2013. The TDSHS informed the restaurant owners and managers of
the fish contamination at the Site and stated that it is illegal to possess fish from the Site
and to purchase and serve those fish. The TDSHS also distributed educational
materials to the restaurants and the Hidalgo County Health Department during the June
2013 visits.
Texas Commission on Environmental Quality Feasibility Study
A 2006 Feasibility Study, conducted by the TCEQ, focused only on the area previously
identified as contaminated with PCBs in the Lower West Main Canal Unlined from the
Siphon's exit to the 90-degree bend in the unlined canal. This study evaluated two
alternatives2: 1) Alternative 1 - Lining of Siphon and Canal, and 2) Alternative 2 -
Construction of New Siphon and Canal (URS Corporation 2006).
Alternative 1 (Lining of Siphon and Canal), from the TCEQ's Feasibility Study, involved
lining the main canal and the Siphon with a suitable material which would prevent the
bed sediment or other potential sources in the canal from contacting the conveyed
waters. This alternative included sliplining of the existing Siphon.
Alternative 2 (Construction of New Siphon and Canal), from the TCEQ's Feasibility
Study, involved the construction of a siphon and canal from the entrance of the existing
Siphon to the 90-degree bend in the Main Canal. This alternative would require the
purchase of a strip of land along the existing canal, if not already available, and
depending on the chosen alignment of the new siphon and canal. The new canal would
be lined since the source area of the PCBs was unknown at the time of the 2006 study.
Since the TCEQ was unable to identify a source of PCB contamination, the State of
Texas referred the site to the EPA for further investigation. The EPA received a letter
from the Governor of Texas on July 26, 2007, stating that Texas supported the EPA's
decision that the Donna Reservoir and Canal System site be considered as a candidate
for the Federal National Priorities List for cleanup.
Agency for Toxic Substances and Disease Registry Public Health Assessment
The Agency for Toxic Substances and Disease Registry (ATSDR) released the Public
Health Assessment (PHA) for the Site for public comment in January 2009. The final
version was released in November 2010 by the TDSHS in conjunction with the ATSDR.
The final report concluded that the consumption of fish from the Site was harmful to
human health due to the PCB concentrations found in the fish. The final report also
concluded that the concentrations of metals, volatile organic compounds, semi-volatile
2 These alternatives are not the same alternatives described in the EPA's Proposed Plan (May 2018) or
this Record of Decision.
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organic compounds, or organochlorine pesticides detected in fish from the Site are not
expected to pose harm to human health.
2.2.3 Texas Department of Health Aquatic Life Order Number 9
The Texas Department of Health (TDH) issued "Aquatic Life Order Number 9" on
February 4, 1994. This order stated that". . . the Donna Irrigation System located in
Hidalgo County is declared a prohibited area for the taking of all species of aquatic life."
According to a sign posted by the TDH at Donna Lake there is a $500 fine for the
possession offish from the Site. This sign also states that "Warning, it is illegal to
possess fish from this water, fish caught from this water may contain harmful
chemicals." The enforcement authority for this order is the Texas Parks and Wildlife
Department (TPWD).
2.2.4 National Priorities List
The Site was listed on the National Priorities List (NPL) in March 2008 due to PCB
contamination in sediment and fish (EPA 2008).
2.2.5 EPA's Remedial Investigation
The EPA began a Remedial Investigation at the Site in September 2012 and ended the
field investigation activities in April 2015. The purpose of the Remedial Investigation (Rl)
and Feasibility Study (FS) was to determine the nature and extent of contamination at
the Site, develop the Human Health and Ecological Risk Assessments, and evaluate the
applicable remedial alternatives to address the contamination at the Site.
More than 80,000 analyses were conducted for more than 480 analytes on samples
collected during the Rl to characterize the chemical and physical characteristics of the
Site. Samples were analyzed for a combination of the following: PCB Aroclors, PCB
Congeners, pesticides, volatile organic compounds, semi-volatile organic compounds,
total target analyte list (TAL) metals, dissolved TAL metals, total organic carbon, total
dissolved solids, total suspended solids, lipids, percent moisture, and passive sampler
samples (semi-permeable membrane device and polyoxymethylene). The specific
media investigated during the Rl included soil, bed/suspended sediment, surface water,
ground water, whole fish, fish fillets, mollusk tissue, and concrete debris and asphalt
(both found in the Lower West Main Canal Unlined segment of the canal system near
the Siphon's exit). The following table provides the number of sample locations
according to media type.
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Number of Sample Locations According to Media Type
Media
Soil
Sediment
Suspended
Sediment
Surface
Water
Ground
Water
Mollusk
Number of
Sample
Locations
53
137
20
48
2
23
Media
Whole Fish
Fish Fillets
SPMD
POM
Concrete
Asphalt
Number of
Sample
Locations
10
82
14
10
2
1
Note:
POM - Polyoxymethylene SPMD - Semi-permeable membrane device
The nature and extent of contamination determined during the Rl is presented in
Section 2.5.4 (Nature and Extent of Contamination) of this ROD.
EPA's Phased Remedial Investigation
The EPA completed thirteen phases of field work. The EPA notified local public officials
of the planned Rl and fish removal action activities prior to each mobilization to the field.
The EPA also notified the print and television media and conducted interviews in
English and Spanish to inform the public of the EPA's activities at the Site and to warn
against consumption of contaminated fish.
Remedial Investigation Phases One through Thirteen
Phase One Rl field activities were conducted from September 17 through 28, 2012, and
included the collection of sediment, surface water, suspended sediment, soil, and air
samples from several areas of the Site, including the Rio Grande River. Sediment and
water samples were also collected from the City of Donna Drinking Water Treatment
Plant as requested by city officials during a community meeting.
Phase Two field activities were conducted from October 15 through 25, 2012. This
phase of the Rl included the fourth fish removal action, fish sample collection, and the
performance of a land-based geophysical survey. The purpose of the survey was to
detect the presence of metallic objects (i.e., buried drums or transformers) possibly
containing PCBs. During the investigation several local residents informed the EPA of
their observation of the presence of metallic receptacles at the Site. This survey
covered approximately 33 acres of land areas adjacent to the banks of the Site's canals
and the Arroyo Colorado River.
Phase Three field activities were conducted from December 10 through 15, 2012, and
included a water-based geophysical survey among other sample collection efforts. This
survey was also designed to locate metallic objects and covered approximately 18
acres submerged underwater in the Site's canals.
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Phases Four through Thirteen began on February 18, 2013, and ended on April 10,
2015, respectively. Among other sample collection efforts, the EPA's "Environmental
Response Team/Scientific Engineering and Response and Analytical Services Contract
Dive Team" used side-scan sonar to scan the Lower West Main Canal Unlined and East
Reservoir to locate underwater objects. Selected objects were then physically examined
by members of the EPA's Region 6 Dive Team. Discrete surface water samples were
collected at the Siphon's entrance; the interior of the Siphon at approximately 150, 350,
550, 750, 950, 1150, 1350, and 1550 feet from the Siphon's entrance; and at the
Siphon's exit (Figure 3 - Existing Siphon Plan, Profile, and Sections; and Figure 19 -
Total Polychlorinated Biphenyl Congeners in Surface Water Samples Collected from
Inside the Siphon). An inspection of the interior of the Siphon was performed using a
Remotely Operated Vehicle (ROV). The ROV which was outfitted with scanning sonar,
multi-beam imaging sonar, and a video camera was used to inspect the entire length of
the interior of the Siphon.
The nature and extent of contamination is described in Section 2.5.4 (Nature and Extent
of Contamination) of this ROD.
2.2.6 CERCLA Fish Removal Actions
The EPA conducted fish removal actions in August 2008, February 2009, August 2009,
October 2012, June 2017, and August 2018. In accordance with CERCLA Section
104(a), 42 U.S.C. § 9604(a), and 40 CFR 300.415 of the NCP, these removal actions
were conducted to address actual or threatened releases of hazardous substances,
pollutants, or contaminants from the Site that may present an imminent and substantial
endangerment to the public health, welfare, or the environment.
These fish removal actions involved the removal of several species offish from the Site
(i.e., alligator gar, freshwater drum, common carp, smallmouth buffalo, channel catfish,
large/smallmouth bass, white bass, blue tilapia, shad, and eel, among other species).
The purpose of the fish removal actions was to remove fish, from the reservoir and
canal system, possibly contaminated with PCBs and which were available for human
consumption. The EPA implemented these removal actions along with a public
awareness campaign using newspaper and television media to warn against
consumption of PCB-contaminated fish that may be harmful to human health.
These fish removal actions, coordinated with the U.S. Fish and Wildlife Service
(USFWS), utilized electroshocking methods. An electrical current was introduced into
the water column which resulted in stunning or disorienting the fish. During the time
when the fish were disoriented they were netted by boat personnel. Approximately
44,863 fish were removed from the Site during the six fish removal actions and
disposed of at an appropriate landfill. Selected whole fish and fillet samples were
analyzed in a laboratory for bioaccumulated concentrations of Total PCBs.
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2.3 COMMUNITY PARTICIPATION
This section of the ROD describes the EPA's community involvement and participation
activities. The EPA has been actively engaged with stakeholders and has encouraged
community participation during the EPA's remedial and removal activities. These
community participation activities during the remedy selection process meet the public
participation requirements in CERCLA 300.430(f)(3) and the NCP.
The EPA periodically met with local, county, and state/federal public officials (i.e.,
Mayors and City Managers for the Cities of Donna and Alamo, Hidalgo County
representatives, Texas Secretary of State representatives, TCEQ, USFWS,
International Boundary and Water Commission [IBWC], and other public officials),
including several community-based organizations (i.e., non-governmental organizations
or others) and representatives from the Irrigation District during the implementation of
the Rl and fish removal actions. These meetings helped the EPA become better aware
of the issues and concerns held by the local officials and the public.
2.3.1 Community Involvement Plan
The Community Involvement Plan (CIP, [EPA 2016]) is central to Superfund's
community involvement program. The EPA developed this CIP to facilitate two-way
communication between the community surrounding the Site and the EPA, and to
encourage community involvement in Site activities. The EPA will utilize the community
involvement activities outlined in this plan to ensure that residents are continuously
informed and provided opportunities to be involved. This plan specifies the outreach
activities that the EPA undertakes to address the community's concerns and
expectations.
The CIP includes background information concerning the community, identification of
community issues and concerns, community involvement activities, a communication
strategy, a contact listing of city/county/state/federal officials, and local print and
television media contacts.
2.3.2 Community/Public Meetings and Fact Sheets
The EPA has conducted community meetings during the course of the Superfund
process. In addition, fact sheets detailing the Site's activities have been published
periodically since the Site was listed on the NPL.
The public meetings announcing the Proposed Plan were held on May 22, 2018, in
Alamo and Donna, Texas. The Proposed Plan described the EPA's rationale for the
selection of the Preferred Alternative. A public comment period for the Proposed Plan
was held from May 7 through June 5, 2018. Public notices of the public meeting and
public comment period were published in two newspapers of general circulation, in
English and Spanish. Additionally, the public notice announcing the Proposed Plan,
public meeting, and comment period was mailed to the contacts included in the Site's
mailing list. Representatives from the EPA provided presentations on the Proposed Plan
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and answered questions about the EPA's Preferred Alternative. Representatives from
the TCEQ and the Texas Department of State Health Services were also present at the
meeting. Oral and written comments were accepted at the meeting and a court reporter
transcribed the discussions held during the meeting. This transcript is included in the
Administrative Record file for the Site. The EPA's responses to each of the comments
received during the public comment period are included in Part 3 (Responsiveness
Summary) of this ROD.
2.3.3 Information Repositories
The Administrative Record file for the Site is available for review at the following
locations:
Donna Public Library
301 S. Main
Donna, Texas 78537
(956) 464-2221
U.S. Environmental Protection Agency, Region 6
1445 Ross Avenue, 7th Floor
Dallas, Texas 75202-2733
Contact: Edward Mekeel, (214) 665-2252 or (800) 533-3508
E-mail: mekeel.edward@epa.gov
Texas Commission on Environmental Quality
Building E, Records Management, First Floor
12100 Park 35 Circle
Austin, Texas 78753
(512) 239-2920 or (800) 633-9363
The Administrative Record file, along with the Site's profile page, is also available on the
internet at the following EPA's website:
http://epa.gov/superfund/donna-reservoir-canal
2.4 SCOPE AND ROLE OF RESPONSE ACTION
The NCP, 40 CFR Section 300.5, defines an "Operable Unit" (OU) as a discrete action
that comprises an incremental step toward comprehensively addressing a site's
contamination problems. The cleanup/remediation of a site can be divided into several
OUs depending on the complexity of the problems associated with the site.
There is only one planned OU for the Site and the EPA's Selected Remedy (i.e.,
Alternative 6) is intended to fully address the threats to human health and the
environment posed by the conditions at the Site by addressing the existing Siphon and
contaminated sediments, and by the implementation offish removals and performance
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monitoring. It is possible that multiple OUs may be considered during the remedial
design of the Selected Remedy to facilitate the implementation of the Selected Remedy.
2.5 SITE CHARACTERISTICS
The following sections of the ROD describe the Site's demographics and cultural
features, physical characteristics, Conceptual Site Model, and the nature and extent of
contamination identified during the Rl.
2.5.1 Demographics and Cultural Features
According to the 2010 Census (U.S. Census Bureau 2010a), the total population of
Donna, Texas, was 15,798. There were a total of 4,613 households with an average
size of 3.42 and the population was 92.3 percent Hispanic or Latino. Median per capita
income in 2000 was $8,569, while the mean household income was $22,800
(U.S. Census Bureau 2000).
According to the 2010 Census (U.S. Census Bureau 2010b), the total population of
Alamo, Texas, was 18,353. There were a total of 5,603 households with an average
size of 3.27 and the population was 84.6 percent Hispanic or Latino. Median household
income was $35,188 (U.S. Census Bureau 2010-2014 American Community Survey
5-Year Estimates).
The greater metropolitan area to which the cities of Donna and Alamo belong is the
McAllen-Edinburg-Mission metropolitan area. The total population of this metropolitan
area in 2010 was 774,769. There were 216,471 total households with an average size
of 3.55 and 90.6 percent of the population were identified as "Hispanic" or "Latino." Per
capita income in 2010 was estimated at $13,525 while the mean household income was
estimated to be $47,576. The U.S. Census Bureau also estimated that 29 percent of
families and 33.4 percent of people in the metropolitan area have an income below the
poverty level. The 2000 Census data indicated that 80 percent of the population speaks
non-English at home and that 39 percent speak English "not well," "not at all," or "less
than well."
Hispanic communities known as "colonias" are common along the Rio Grande River,
where they exist often without basic services such as access to adequate water,
sewage, housing, and health services. The Texas Department of Housing and
Community Affairs characterizes these communities as low income and high
unemployment areas. Five such colonias have been identified immediately south of
Donna (Texas Secretary of State 2011).
2.5.2 Physical Characteristics
This section of the ROD describes the following physical characteristics of the Site:
plant species and wildlife, ground water, surface water, sediment, and soils.
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Plant Species and Wildlife
Most of the native vegetation of the Lower Rio Grande Valley has been cleared for
agriculture (MacWhorter 2015). Where native habitat remains in Hidalgo County, it
contains vegetative communities unique to the Lower Rio Grande Valley. The area is
characterized by a semi-arid and subtropical climate (Jahrsdoerfer and Leslie 1988) and
includes mid-delta thorn forest, which once covered most of the Rio Grande Delta.
Today, less than 5 percent of this plant community remains in the area. The small
remnant tracts can be found in fence rows, highway rights-of-way, canals, and ditch
banks (Jahrsdoerfer and Leslie 1988).
Plant species in the area around the Site are expected to include agricultural crops and
small stands of shrubs and low trees. Wildlife in these terrestrial habitats is expected to
include birds, mammals, reptiles, and amphibians typical of the South Texas Plains. It is
also expected that livestock will utilize the terrestrial habitats irrigated by the canals. The
land use in the area is primarily agricultural; therefore, wildlife would also include
species habituated to man-made environments such as the reservoir and canal system
comprising the Site. Based on field observation, the banks of the reservoir and canal
system are dominated by giant reed, including riprap, and are unlikely to provide
substantial habitat preferred by most species. The outer banks of the reservoir and
canal system are dominated by agricultural fields.
The following types of fish were removed from the Site during the 2012 fish removal
action and are common in the reservoir and canal system: common carp, grass carp,
gizzard shad, threadfin shad, buffalo, freshwater drum, redear sunfish, redbreast
sunfish, bluegill, warmouth, largemouth bass, smallmouth bass, white crappie,
Rio Grande cichlid, blue tilapia, channel catfish, blue catfish, white bass, longnose gar,
alligator gar, spotted gar, Mexican tetra, bigmouth sleeper, plecostomus, and silvers
love (Dynamac Corporation 2013).
Birds expected at the Site include common species such as redwing blackbird, green
jay, and red-tailed hawk that utilize the riparian corridor, as well as water birds such as
great blue heron that utilize the waterways and reservoir. It is anticipated that the Site is
used by both full-year resident and migratory birds. Mammals likely include raccoon, red
fox, rodents, and shrews. Reptiles may include a variety of snakes and turtles that
utilize the waterways. Amphibians may include the leopard frog and Mexican burrowing
toad.
Several threatened and endangered (T&E) species were evaluated during the
ecological risk assessment. These T&E species included the Coues' rice rat, interior
least tern, reddish egret, false spike mussel, Salina mucket, and Texas hornshell. Some
or all of these species may or may not be present at the Site because of limited habitat.
According to the TPWD the Coues' rice rat prefers habitat in cattail-bulrush marshes
and aquatic grassy zones near oxbow lakes. From aerial photographs the Northwest
Reservoir appears to be the remnants of an oxbow lake; however, this portion of the
reservoir system comprises a relatively small area in comparison to the entire reservoir
and canal system. The canals are not a suitable habitat for this T&E species.
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Ground Water
Hidalgo County relies primarily on surface water from the Rio Grande River, which
provides approximately 98 percent of water used in the Lower Rio Grande Valley
(McCoy 1990). As such, ground water is not the primary source of water near the Site.
The Evangeline and Chicot aquifers do yield moderate to large quantities of fresh to
moderately saline water in Hidalgo County (McCoy 1990); however, some of this water
is not suitable for irrigation or drinking water purposes (McCoy 1990). It is anticipated
that future ground water use will remain the same as current ground water use in
Hidalgo County, which has only limited use as a source of irrigation water, domestic
water, and municipal water.
The depth to ground water measured in the two monitoring wells installed in the canal
levee during the Rl, near the Siphon's exit, was approximately 27 feet below the
ground's surface. The depth to water relative to the agricultural fields is approximately 7
feet below the ground's surface, assuming the levee is approximately 20 feet above the
surrounding agricultural fields.
Surface Water
The surface water for the entire reservoir and canal system is a freshwater system fed
from the Rio Grande River. The volume and velocity of the water entering the system
and thus the reservoir can be controlled by the number of operational pumps. The
canals and Siphon have been designed to transport water at a maximum flow rate of
400 cubic feet/second (cfs) measured at the Rio Grande River pumping station
operated by the Irrigation District. The flow rate which is variable throughout the year
and directly corresponds to the agricultural and municipal demand usually varies
between 40 to 300 cfs during the year. Thus, variable pumping rates correspond to
variable water levels in the canal system, ranging from a foot or less in some places
during periods of low agricultural water demands (e.g., rainy cold seasons) to over 15
feet in others during periods of high agricultural water demands (e.g., dry summers).
The water depth in the reservoirs varies from 1 to 3 feet. The surface water has high
conductivity (salinity), during periods of drought, and some estuarine fish species have
been found during the fish removal actions. It is anticipated that future surface water
use will remain the same as current surface water use in Hidalgo County, which has
significant use as a source of irrigation water and municipal water.
Sediment
The unlined reservoirs and canals have the thickest sediment, up to a maximum
recorded thickness of 20 inches in the Lower West Main Canal Unlined near the
Siphon's exit. The lined canals tend to have very limited to no sediment deposition.
Sediment within the system is primarily fine grained and consisting of silt and clay with
minor amounts of fine sand which is light gray to dark gray in color.
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Soils
The Site's soils are identified as groups of clay, silty clay, and clayey loam within the
U.S. Department of Agriculture Classification System. Clay content ranges from 22 to
64 percent, silt content ranges from 30 to 46 percent, sand content ranges from 1 to 35
percent (most samples are below 5 percent), and gravel content ranges from 0 to 14
percent. The dominant soil type extending from the Rio Grande River to the City of
Donna is Harlingen Clay, which is a deep nearly level soil primarily composed of
calcareous clay. Harlingen Clay is moderately well drained, surface runoff is very slow,
permeability is very low, and available water capacity is low (U.S. Department of
Agriculture 1981). It is anticipated that future uses of the soils will remain the same as
current soils use in Hidalgo County, which have significant use as an agricultural
resource.
2.5.3 Conceptual Site Model
A Conceptual Site Model (CSM) identifies the sources of contamination, release
mechanisms, pathways for contaminant transport, the impacted media, and potential
human and ecological receptors. The CSM is used to organize and communicate
information about a site and is the basis for the remedial action presented in this ROD.
Separate CSMs have been developed for human and ecological receptors. The CSMs,
in tabular format, for human health and ecological receptors are depicted in Figure 22
(Human Health Conceptual Site Model) and Figure 24 (Ecological Conceptual Site
Model), respectively. A CSM, in graphical format, is depicted in Figure 27 (Pictorial
Conceptual Site Model). Based on the human health and ecological risk assessments,
complete pathways for contaminant transport were identified for both human and
ecological receptors to fish tissue and sediment, respectively, as depicted in the tabular
and graphical CSMs for human and ecological receptors.
The Site includes a system of reservoirs and canals containing fish and sediment with
elevated concentrations of PCBs. Fish with detectable levels of Aroclor-1254, Aroclor-
1260, or PCB Congeners have been collected from several segments of the reservoir
and canal system sampled as described in Section 2.5.4 (Nature and Extent of
Contamination). Sediment concentrations for Total PCB Aroclors and Total PCB
Congeners decrease with distance in the Lower West Main Canal Unlined from the
Siphon's exit to results reported below detection levels further downgradient of the
Siphon's exit as shown in Figures 4 (Concentrations of Aroclor-1254 and Aroclor-1260
in Sediment) through 17 (Concentrations of Total Polychlorinated Biphenyl Congeners
in Sediment). From the information gathered during the Rl, it may be concluded that
PCBs are bioaccumulating in fish, and the largest known accessible source of PCBs at
the Site for fish is the sediment in the canal system.
The likely source of PCB contamination at the Site has been determined to be the
Siphon, based on the data collected during the Rl and the weight of evidence. It is likely
that the Siphon's construction/repair materials (e.g., concrete, caulking, grout, or
sealants) were a primary source of contamination at the Site.
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Sediment data collected during the Rl initially suggested the following options for the
location of the source of PCB contamination:
1) Between the Siphon's exit and the 90-degree bend in the Lower West Main
Canal Unlined in the area with the most elevated concentrations of PCBs in
sediment,
2) Immediately upgradient of the Siphon's exit and downgradient of the Main Canal
(i.e., in the 160-feet concrete-lined section between the weir and the Siphon's
exit), or
3) No longer present at the Site.
Based on the following results of the Rl, Option 2, excluding the 160 feet of concrete-
lined section between the weir and the Siphon's entrance, may be the likely source of
contamination.
Land- and water-based geophysical surveys were conducted in the Lower West Main
Canal Unlined to identify objects requiring assessment as potential sources of PCBs.
These targets were investigated during a scientific diver survey. The scientific divers
found no indication of PCB-laden objects in the canal, which eliminates a possible
source in the Lower West Main Canal Unlined. Surface water samples collected from
within the Siphon and passive samples collected downgradient of the Siphon's exit
indicate that a likely continuing source of PCB contamination exists at the Site (Figures
19 through 21). The remote-operated vehicle underwater sonar and camera inspection
of the Siphon indicates that no foreign objects (e.g., transformers, drums) are located
within the interior of the Siphon.
The hydraulics of the Siphon indicate that much, if not all, of the time a positive pressure
is exerted from the interior of the Siphon. This means that water is forced out of cracks
or leaking joints in the Siphon and the chances of contamination leaking into the Siphon
are low. Therefore, by weight of evidence from the field investigations, the likely primary
source of PCBs is located within the Siphon and is not a foreign object (e.g.,
transformer).
It is possible that Siphon construction or repair materials (e.g., concrete, caulking, grout,
or sealants) were the primary source of contamination at the Site. PCBs were
domestically manufactured from 1929 to 1979 and used for a variety of purposes (EPA
2013). PCBs were used in capacitors, transformers, caulking, surface coatings, and
pesticide extenders, among other uses. The EPA could not locate any information to
indicate that PCBs were historically used as pesticide extenders in the surrounding
agricultural fields. Records for the construction of the Siphon could not be located and
samples from the Siphon's construction or repair materials were not collected during the
Rl because the Siphon is in continuous use. Technical challenges, health and safety
concerns, and high cost associated with a Siphon in continuous use (i.e., always full of
water) resulted in the decision to not attempt Siphon construction or repair material
sample collection. The Siphon was constructed in approximately 1926 and is probably
approaching the end of its design life. It is possible that the concrete and steel used to
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construct the Siphon may have degraded over time and any direct physical efforts to
sample the Siphon could damage the Siphon.
As depicted in the graphical CSM shown in Figure 27 (Pictorial Conceptual Site Model),
PCBs enter the canal system by leaching into surface water during flow through the
Siphon. PCBs are hydrophobic and adhere to particles in the surface water. The rapid
decrease in surface water velocity as water exits the Siphon results in the deposition of
particulates that have adsorbed the PCBs, resulting in a gradient of decreasing PCB
sediment concentrations with distance from the Siphon's exit. Fish and other aquatic
organisms bioaccumulate and biomagnify PCBs over time and then these fish are
available for human consumption.
2.5.4 Nature and Extent of Contamination
The nature and extent of contamination at the Site was determined during the Rl. The
likely source of PCB contamination at the Site has been determined to be the Siphon,
based on an evaluation of the data collected during the Rl and weight of evidence.
Total PCB Aroclors and Total PCB Congeners (i.e., 209 Congeners) were investigated
at the Site. Fish with detectable levels of Aroclor-1254 or Aroclor-1260 have been
collected from all segments of the canal and reservoir system sampled (i.e., Main
Canal, Lower West Main Canal, and West Reservoir). The maximum detected
concentration of Total PCB Aroclors in fish tissue is 8.1 mg/kg found in a sample of
smallmouth buffalo, a bottom feeder, from the Lower West Main Canal Unlined near the
Siphon's exit (see "Sample BUF-153-F" [2015 Area 3] on Figure 18 - Fish
Concentrations of Aroclor-1254, Aroclor-1260, and Total Polychlorinated Biphenyl
Congeners). The maximum detected concentration of Total PCB Congeners in fish
tissue is 150 mg/kg also found in a smallmouth buffalo caught in the Lower West Main
Canal Unlined near the Siphon's exit (see "Sample BUF-170-F" [2015 Area 4] on Figure
18).
Maximum detected Total PCB Congener concentrations observed in fish are
approximately 25 times higher than those observed in sediment (150 mg/kg in fish to
6.1 mg/kg in sediment). Maximum detected Total PCB Aroclor concentrations observed
in fish are very similar to those observed in sediment (8.1 mg/kg in fish to 11 mg/kg in
sediment). Average detected Total PCB Congener concentrations observed in fish are
approximately 20 times higher than those observed in average detected sediment
concentrations (7.2 mg/kg in fish to 0.41 mg/kg in sediment). Average detected Total
PCB Aroclor concentrations observed in fish are approximately 3 times higher than
those observed in average detected sediment concentrations (0.6 mg/kg in fish to 0.24
mg/kg in sediment). These data support the conclusion that PCBs are bioaccumulating
in fish.
Sediment with the highest concentrations of PCBs at the Site is in the Lower West Main
Canal Unlined which is located hydraulically downgradient of the Siphon's exit (Figure 8
- Concentrations of Aroclor-1254 and Aroclor-1260 in Sediment, Figure 9 -
Concentrations of Total Polychlorinated Biphenyl Congeners in Sediment, and Figure
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25 - Sediment Remediation Area Based on a Sediment Cleanup Goal of 0.043 mg/kg).
The highest observed concentration of Total PCB Aroclors in sediment is 11 mg/kg,
collected near the Siphon's exit, which was reported entirely as Aroclor-1254 (see
"Sample LWCU-160-SE" [2013] on Figure 8). The highest observed concentration of
Total PCB Congeners in sediment is 6.1 mg/kg, also collected near the Siphon's exit
(see "Sample LWMCU-160-SE" [2013] on Figure 9). Sediment concentrations of Total
PCB Aroclors and Total PCB Congeners decrease with distance in the Lower West
Main Canal Unlined from the Siphon's exit to results reported below detection levels
hydraulically downstream of the exit.
Passive sampler data, from semi-permeable membrane devices and polyoxymethylene
(POM) samplers, indicate that fish may receive PCBs from the water column directly or
from prey or sediment they ingest. However, the largest known PCB source at the Site
directly accessible to fish is sediment in the canal system. POM sampler concentrations
of Total PCB Congeners in both surface water and sediment pore water generally
decrease with distance from the Siphon's exit also indicating that the PCBs are likely
sourced from the Siphon.
Discrete surface water samples collected from the entrance, at multiple points from the
interior, and at the exit of the Siphon indicate a general increase in concentrations of
Total PCB Congeners along the interior length of the Siphon (Figure 3 - Existing Siphon
Plan, Profile, and Sections; and Figure 19-Total Polychlorinated Biphenyl Congeners
in Surface Water Samples Collected from Inside the Siphon). The increase in Total PCB
Congeners surface water concentrations along the length of the Siphon suggests that
the likely source is not a single point but is present along the entire length of the Siphon.
PCBs enter the canal system by leaching into surface water during flow through the
Siphon. PCBs are hydrophobic and adhere to particles in the surface water and
sediment. The rapid decrease in surface water velocity as water exits the Siphon results
in deposition of particulates that have adsorbed PCBs which resulted in a gradient of
decreasing PCB sediment concentrations with distance from the Siphon's exit. Fish and
other aquatic organisms have bioaccumulated and biomagnified PCBs through the food
chain over a period of decades.
The water-based geophysical survey and side-scan sonar results provided targets for
further investigation by the EPA's scientific divers in the Lower West Main Canal
Unlined. The scientific divers found no indication of PCB-laden objects (e.g.,
transformers or drums) in the canal which eliminates a possible source in the Lower
West Main Canal Unlined. The land-based geophysical survey also found no indication
of PCB-laden objects beneath the surface of the ground along the banks/levees of the
canals.
The ROV inspection of the Siphon indicates that no foreign objects (e.g., transformers
or drums) are located within the interior of the Siphon. The hydraulics of the Siphon
indicate that for most of the time a positive pressure is exerted from the interior of the
Siphon. This means that water is forced out of cracks or leaking joints in the Siphon,
and the chances of contamination leaking into the Siphon are low. Therefore, the
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available data and evidence indicate that the primary likely source of PCBs is located
within the Siphon and is not a foreign object.
It is possible that Siphon construction/repair materials (e.g., concrete, caulking, grout, or
sealants) were the primary source of contamination at the Site. PCBs were domestically
manufactured and used for a variety of purposes from approximately 1929 to 1979. The
information recently provided by the Irrigation District indicates that the Siphon was
damaged by floodwaters in 1967, during Hurricane Beulah, and may have been
repaired. Samples of the Siphon materials (e.g., concrete, caulk, grout, or sealants)
were not collected by the EPA during the Rl due to health and safety concerns,
technical challenges, and high cost. Additionally, all options considered for the physical
inspection of the interior of the Siphon introduced the potential to damage the structural
integrity of the Siphon. The Siphon was constructed in approximately 1926 and is
probably approaching the end of its design life. It is possible that the concrete and steel
used to construct the Siphon may have degraded over time and any direct physical
efforts to sample the Siphon could damage the Siphon.
2.6 CURRENT AND POTENTIAL FUTURE LAND AND RESOURCE USES
This section of the ROD summarizes the current and potential (i.e., reasonably
anticipated) future land and resource uses at the Site and areas surrounding the Site.
This information forms the basis for the exposure assessment assumptions and risk
characterization conclusions discussed in Section 2.7 (Summary of Site Risks).
Ground water is not the primary source of water near the Site. Hidalgo County relies
primarily on surface water from the Rio Grande River, which provides approximately 98
percent of water used in the Lower Rio Grande Valley (McCoy 1990). As such, it is
anticipated that future ground water use will remain the same as the current ground
water use in Hidalgo County, which has only limited use as a source of irrigation water,
domestic water, and municipal water.
The surface water, supplied by the Irrigation District, is used for the irrigation of
agricultural fields, which surround the Site, and for drinking water for the City of Donna
and the North Alamo Water Supply Corporation Plant No. 5. It is anticipated that future
surface water use will remain the same as the current surface water use in Hidalgo
County, which has significant use as a source of municipal water supplies and
agricultural irrigation water.
Most of the land area (i.e., soils) near the Site is currently used for commercial
agriculture. The primary crops cultivated in Hidalgo County are sugarcane, sorghum,
cotton, corn, vegetables, and citrus fruits. In 2006, Hidalgo County was the state's
largest sugarcane producer with 882,000 tons harvested and the state's largest
producer of grain sorghum with 4,409,000 bushels harvested (Texas Comptroller of
Public Accounts 2008). In addition, Hidalgo County contains 85 percent of the citrus
acres in Texas, making Texas the nation's third-largest citrus producer (Sauls 2008). It
is anticipated that future land use will remain the same as the current land use in
Hidalgo County, which has significant use as a source of agricultural production.
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The current and potential future land and resource uses for the Site will remain the
same. A qualitative assessment of consumption of produce, including livestock, from the
adjacent agricultural fields was conducted during the exposure assessment phase of
the human health risk assessment (see Section 2.7.1 - Summary of the Human Health
Risk Assessment). These exposure routes were considered to contribute insignificant
risks due to the type and concentrations of contaminants detected in Site media. Use of
the water from the reservoir and canal system as drinking water was also evaluated and
found to be safe for human consumption. Based on the ecological risk assessment,
cleanup of the Site to human health Remediation Goals will also be protective of
ecological receptors (see Section 2.7.2 - Summary of the Ecological Risk Assessment).
2.7 SUMMARY OF SITE RISKS
A Human Health Risk Assessment (HHRA) and an Ecological Risk Assessment (ERA)
were conducted to evaluate potential exposure pathways and estimate potential risks
posed to human and ecological receptors because of exposure to contaminants in Site
media. These assessments provide the basis for taking a remedial action at the Site
and identify the contaminants and exposure pathways that will be addressed by the
Selected Remedy identified in this ROD.
Section 2.7.1 (Summary of the Human Health Risk Assessment) provides a summary of
the relevant portions of the HHRA, as presented in the final Human Health Risk
Assessment (Revision 2) (EA 2016b). Section 2.7.2 (Summary of the Ecological Risk
Assessment) provides a summary of the relevant portions of the ERA, as presented in
the final Ecological Risk Assessment (Revision 3) (EA 2016c). Section 2.7.3 (Basis for
Action) discusses the basis for action at the Site.
2,7,1 Summary of the Human Health Risk Assessment
The HHRA estimates potential health risks the Site poses to anticipated receptors if no
action were taken. It provides the basis for taking a remedial action at the Site and
identifies the contaminants and exposure pathways that need to be addressed by the
remedial action. This section of the ROD summarizes the results of the HHRA.
Identification of Chemicals of Concern
The following table provides the chemicals of concern (COCs) and exposure point
concentrations (EPCs) for each of the COCs detected in Site media (i.e., the
concentration used to estimate the exposure dose and risk from each COC). The table
includes the number of samples for each exposure unit, the frequency of detection (i.e.,
the number of times the chemical was detected in the samples collected at the Site),
and what statistical measure was used to derive the EPCs.
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Chemicals of Concern and Exposure Point Concentrations
Scenario Timeframe: Current/Future
Medium:
Surface Water
Exposure Medium: Fish Tissue
Concentration Detected
Exposure Point
Exposure
Chemical of
(mg/kg)
Frequency of
Concentration
Statistical
Unit
Concern
Min
Max
Detection
(mg/kg)
Measure
Tissue - Buffalo Fillet
Aroclor-1254
0.065
4.5
8/12
1.69
95% UCL
DRCS
Aroclor-1260
0.14
3.6
2/12
3.6
Max
PCB Congeners
0.016
150
3/3
150
Max
Tissue - Gar Fillet
Aroclor-1254
0.15
0.95
3/10
0.45
95% UCL
DRCS
Aroclor-1260
0.085
0.83
9/10
0.66
95% UCL
PCB Congeners
0.41
0.41
1/1
0.41
Max
Tissue - Catfish Fillet
Aroclor-1254
0.043
0.96
8/18
0.34
95% UCL
DRCS
Aroclor-1260
0.055
0.72
5/18
0.15
95% UCL
PCB Congeners
0.0097
4.0
4/4
3.83
95% UCL
Tissue - Largemouth Bass Fillet
Aroclor-1254
0.031
0.14
4/19
0.05
95% UCL
DRCS
Aroclor-1260
Not Detected
-
-
-
PCB Congeners
0.0015
2.1
7/7
2.1
Max
Tissue - Common Carp Fillet
Aroclor-1254
0.0042
1.4
11/36
0.15
95% UCL
DRCS
Aroclor-1260
0.037
0.22
2/36
0.22
Max
PCB Congeners
0.005
7.2
3/3
7.2
Max
Tissue - All Fish Fillet Results
Aroclor-1254
0.0042
4.5
35/105
0.43
95% UCL
DRCS
Aroclor-1260
0.037
3.6
18/104
0.23
95% UCL
PCB Congeners
0.005
150
20/20
29.4
95% UCL
Notes:
95% UCL - 95 percent cent upper confidence limit
DRCS - Donna Reservoir and Canal System
Max - maximum result
Min - minimum result
mg/kg - milligram(s) per kilogram
Exposure Assessment
Based upon the CSM presented in Section 2.5.3 (Conceptual Site Model), the following
exposure pathways were quantitatively evaluated in the HHRA:
• Resident adult and child - Ingestion, inhalation, and dermal contact with soil;
• Agricultural worker - Ingestion, inhalation, and dermal contact with soil; and
• Recreational user (adult, adolescent, and child) - Ingestion of and dermal contact
with surface water and sediment; ingestion offish tissue.
Quantitative risk estimates were not calculated for entire age ranges within the receptor
groups under the potential exposure scenarios; however, the receptor groups included
in the quantitative evaluation were selected to be protective of the entire age range of
receptors of concern.
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A qualitative assessment of consumption of produce and livestock from the adjacent
agricultural fields was also conducted. These exposure routes were considered to
contribute insignificant risks due to the type and concentrations of contaminants
detected in Site media. Use of the water from the reservoir and canal system as a
drinking water source was also evaluated and found to be safe for human consumption.
Exposure pathways are presented in the CSMs (Figure 22 - Human Health Conceptual
Site Model, and Figure 27 - Pictorial Conceptual Site Model) and are discussed in
further detail in Section 2.2 (Exposure Assessment) of the HHRA (EA 2016b). Appendix
A (Summary of Human Health Exposure Factors and Intake Equations) provides a
summary of the exposure factors and intake equations used to evaluate potential risks
to human receptor groups at the Site.
No unacceptable risks were identified for any receptor group due to exposure to soil,
ground water, sediment, or surface water at the Site. Therefore, the subsequent
discussions have been limited to exposure media (i.e., fish tissue), exposure routes
(i.e., consumption), and the COCs (i.e., Total PCBs) identified as risk drivers at the Site.
Toxicity Assessment
The following tables provide the carcinogenic and noncarcinogenic risk information
relevant to the COCs identified in the HHRA (EA 2016b).
Cancer Toxicity Data
Chemical of
Concern
Oral
Cancer
Slope
Factor
Oral
Absorption
Efficiency
for Dermal
(Gl ABS)(1)
Absorbed
Cancer
Slope
Factor for
Dermal(2)
Units
Weight of
Evidence/
Cancer
Guideline
Description
Source
Date (3)
(mm/dd/yyyy)
Aroclor-1254
2.0
1
2.0
per (mg/kg-day)
B2
IRIS
8/10/2015
Aroclor-1260
2.0
1
2.0
per (mg/kg-day)
B2
IRIS
8/10/2015
PCB Congeners
2.0
1
2.0
per (mg/kg-day)
B2
IRIS
8/10/2015
Notes:
Weight of Evidence:
(1) Taken from EPA 2004 Guidance.
(2) Dermal Toxicological values adjusted from oral values using USEPA2004
recommended chemical-specific gastrointestinal absorption factors
(Gl ABS). Cancer Slope Factors are divided by the Gl ABS.
(3) IRIS - Integrated Risk Information System. For IRIS values, the date IRIS
was searched is provided.
A - Human carcinogen
B1 - Probable human carcinogen -
indicate that limited human data
are available
B2 - Probable human carcinogen -
indicates sufficient evidence in
animals and inadequate or no
evidence in humans
C - Possible human carcinogen
D - Not classifiable as a human
carcinogen
E - Evidence of noncarcinogenicity
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Non-Cancer Toxicity Data
Chemical of
Concern
Chronic/
Subchronic
Oral RfD
Value
(mg/kg-day)
Oral to
Dermal
Adjustment
Factor*1'
(Gl ABS)
Adjusted
Dermal
RfD(2)
(mg/kg
bw-day)
Primary
Target
Organ
Combined
Uncertainty/
Modifying
Factors
Sources
of RfD:
Target
Organ
Dates of RfD:
Target
Organ(3)
(mm/dd/yyyy)
Aroclor-1254
Chronic
2.0E-05
1
2.0E-05
Skin
300/1
IRIS
8/10/2015
Aroclor-1260
NA
NA
1
NA
NA
NA/NA
IRIS
8/10/2015
PCB Congeners
NA
NA
1
NA
NA
NA/NA
IRIS
8/10/2015
Notes:
mg/kg-day - milligrams per kilogram per day
mg/kg bw-day - milligrams per kilogram of body weight per day
NA - Not Applicable
RfD - Reference Dose
(1) Taken from EPA 2004 Guidance.
(2) Dermal toxicological values adjusted from oral values using EPA 2004 recommended chemical-specific gastrointestinal
absorption factors (Gl ABS). RfDs are multiplied by the Gl ABS.
(3) IRIS - Integrated Risk Information System. For IRIS values, the date IRIS was searched is provided.
Risk Characterization
For carcinogens, risks are generally expressed as the incremental probability of an
individual developing cancer over a lifetime because of exposure to a potential
carcinogen. Excess lifetime cancer risk is calculated from the following equation:
Risk = LADI x SF
Where:
Risk = Unitless probability (e.g., 2x10~5) of an exposed individual developing
cancer
LADI = Lifetime cancer average daily intake (mg/kg/day)
SF = Cancer slope factor (mg/kg/day)-1
These risks are probabilities that are usually expressed in scientific notation (e.g.,
1 xl0"6or 10~6). An excess lifetime cancer risk of 10~6 indicates that an individual
experiencing the reasonable maximum exposure estimate has a 1 in 1,000,000 chance
of developing cancer as a result of Site-related exposure. This is referred to as an
"excess lifetime cancer risk" because it would be in addition to the risks of cancer
individuals face from other causes such as smoking or excessive exposure to sunlight.
The chance of an individual developing cancer from other causes has been estimated to
be as high as one in three. The EPA's generally acceptable risk range for Site-related
exposures is 10"4 to 10"6.
The potential for non-carcinogenic effects is evaluated by comparing the average daily
intake (ADI) to the chemical-specific reference dose (RfD). An RfD represents a level
that an individual may be exposed to that is not expected to cause deleterious effects.
The ratio of exposure to toxicity is called a hazard quotient (HQ), which is derived as
shown in the equation below:
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HQ = ——
RfD
Where:
HQ = Hazard quotient; ratio of average daily intake level to acceptable daily
intake level (unitless)
ADI = Calculated non-carcinogenic average daily intake (mg/kg/day or
mg/m3)
RfD = Reference dose (mg/kg/day)
If the ADI exceeds the RfD, the HQ will exceed a ratio of one (1.0) and there may be
concern that potential adverse systemic health effects will be observed in the exposed
populations. If the ADI does not exceed the RfD, the HQ will not exceed 1.0 and there
will be no concern that potential adverse systemic health effects will be observed in the
exposed populations. However, if the sum of several HQs exceeds 1.0, and the
contaminants affect the same target organ, there may be concern that potential adverse
systemic health effects will be observed in the exposed populations. In general, the
greater the value of the HQ above 1.0 the greater the level of concern; however, the HQ
does not represent a statistical probability that an adverse health effect will occur.
For consideration of exposures to more than one chemical causing systemic toxicity via
several different pathways, the individual HQs are summed to provide an overall hazard
index (HI). If the HI is less than 1.0, then no adverse health effects are likely to be
associated with exposures at the Site. However, if the total HI is greater than 1.0,
separate endpoint-specific His may be calculated based on toxic endpoint of concern or
target organ (e.g., HQs for neurotoxins are summed separately from HQs for renal
toxins). Only if an endpoint-specific HI is greater than 1.0 is there reason for concern
about potential health effects for that endpoint.
The HHRA evaluated potential risks due to the consumption offish (i.e., fish fillets)
based on the fish tissue results. It also evaluated potential risks based on consumption
of individual fish species. Individual fish species evaluated during the HHRA included
catfish, buffalo, gar, largemouth bass, and the common carp. The results of the HHRA
determined that there were unacceptable risks associated with each of the individual
fish species evaluated, and cleanup goals at the Site would be applicable to all fish
species. Therefore, the summary of cancer and non-cancer risks presented in this
section of the ROD have been limited to those results calculated based on the entire
fish tissue data set collected from the Site. The results of individual species evaluations
are included in the HHRA (EA 2016b).
The HHRA identified PCBs in fish tissue as the primary risk drivers at the Site and
evaluated potential risks for individual Aroclors as well as Total PCB Congeners.
However, the data set for PCB Congeners was significantly smaller than that of the
individual Aroclors, with 105 fish tissue samples analyzed for Aroclors, and only 20
samples analyzed for PCB Congeners. For many of the tissue samples, the individual
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Aroclors and PCB Congener analysis was not performed on the same sample;
therefore, the results for the PCB Congeners were evaluated separately from other
contaminants in fish tissue. The evaluation of individual fish species was also not
performed for the PCB Congener evaluation due to the low number of samples
analyzed for PCB Congeners within each species. Risks for Total PCB Congeners were
evaluated assuming a high-risk PCB. As a result, only carcinogenic toxicity values are
available for Total PCB Congeners, and an estimate of non-carcinogenic hazards is not
available.
The following tables provide a summary of cancer and non-cancer risks for the COCs
and exposure media identified as risk drivers at the Site. The following risk estimates
are based on a reasonable maximum exposure, which is defined as the highest
exposure that could reasonably be anticipated to occur for a given exposure pathway
and scenario at the Site. Additional discussion is provided in Section 3.0 (Human Health
Risk Assessment Results) of the HHRA (EA 2016b).
Risk Characterization Results for the Adult Recreational User
Cancer Risks for Adult Recreational Users - Individual Aroclors
Location: Donna Reservoir and Canal System (DRCS)
Scenario Timeframe: Current/Future
Receptor Population: Recreational User
Receptor Age: Adult
Medium
Exposure
Medium
Exposure
Point
Chemical
Cancer Risk
Ingestion
Dermal
Exposure
Inhalation | Routes Total
Surface
Water
Fish
DRCS
Aroclor-1254
1.0E-04
__
I 1.0E-04
Aroclor-1260
5.5E-05
—
5.5E-05
(Total)
1.6E-04
—
I 1.6E-04
Total Risk Across Fish
| 2E-04
Cancer Risks for Adult Recreational Users - Total PCB Congeners
Location: Donna Reservoir and Canal System (DRCS)
Scenario Timeframe: Current/Future
Receptor Population: Recreational User
Receptor Age: Adult
Medium
Exposure
Medium
Exposure
Point
Chemical
Cancer Risk
Ingestion
Dermal
Exposure
Inhalation | Routes Total
Surface
Water
Fish
DRCS
PCB Congeners
7.2E-03
—
I 7.2E-03
(Total)
7.2E-03
—
| 7.2E-03
Total Risk Across Fish
| 7E-03
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Non-Cancer Hazards for Adult Recreational Users
Location: Donna Reservoir and Canal System (DRCS)
Scenario Timeframe: Current/Future
Receptor Population: Recreational User
Receptor Age: Adult
Medium
Exposure
Medium
Exposure
Point
Chemical
Non-Cancer Hazard Quotient
Primary
Target Organ
Ingestion
Dermal
Exposure
Inhalation | Routes Total
Surface
Water
Fish
DRCS
Aroclor-1254
Skin
7.0
—
I 7.0
Aroclor-1260
NA
—
—
..
(Total)
7.0
—
| 7.0
Total Hazard Index Across Fish
I 7.0
As shown in the risk characterization tables for the adult recreational user, the
cumulative cancer risk estimate for the adult recreational user (i.e., 2x10"4) exceeded
the EPA's acceptable cancer risk range based on exposure to individual Aroclors
through consumption offish tissue. Cancer risk estimates based on Total PCB
Congeners (i.e., 7*10~3) also exceeded the EPA's acceptable cancer risk range. In
addition, the calculated non-cancer HI exceeded the acceptable threshold of 1.0, with
Aroclor-1254 (i.e., HQ = 7.0) identified as a COC with a HQ exceeding 1.0.
Risk Characterization Results for the Adolescent Recreational User
Cancer Risks for Adolescent Recreational Users - Individual Aroclors
Location: Donna Reservoir and Canal System (DRCS)
Scenario Timeframe: Current/Future
Receptor Population: Recreational User
Receptor Age: Adolescent
Medium
Exposure
Medium
Exposure
Point
Chemical
Cancer Risk
Ingestion
Dermal
Exposure
Inhalation | Routes Total
Surface
Water
Fish
DRCS
Aroclor-1254
5.3E-05
—
I 5.3E-05
Aroclor-1260
2.8E-05
—
2.8E-05
(Total)
8.1E-05
—
I 8.1E-05
Total Risk Across Fish
| 8E-05
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Cancer Risks for Adolescent Recreational Users - Total PCB Congeners
Location: Dc
Scenario Tir
Receptor Pc
Receptor Ac
>nna Reservoir and Canal System (DRCS)
rieframe: Current/Future
pulation: Recreational User
e: Adolescent
Medium
Exposure
Medium
Exposure
Point
Chemical
Cancer Risk
Ingestion
Dermal
Exposure
Inhalation | Routes Total
Surface
Water
Fish
DRCS
PCB Congeners
3.7E-03
—
I 3.7E-03
(Total)
3.7E-03
—
I 3.7E-03
Total Risk Across Fish | 4E-03
Non-Cancer Hazards for Adolescent Recreational Users
Location: Donna Reservoir and Canal System (DRCS)
Scenario Timeframe: Current/Future
Receptor Population: Recreational User
Receptor Age: Adolescent
Medium
Exposure
Medium
Exposure
Point
Chemical
Non-Cancer Hazard Quotient
Primary
Target Organ
Ingestion
Dermal
Exposure
Inhalation | Routes Total
Surface
Water
Fish
DRCS
Aroclor-1254
Skin
9.3
—
I 9.3
Aroclor-1260
NA
—
—
..
(Total)
9.3
—
I 9.3
Total Hazard Index Across Fish
| 9.3
As shown in the risk characterization tables for the adolescent recreational user, the
cancer risk estimate for the adolescent recreational user (i.e., 8x10~5) was found to be
near the upper end of the EPA's acceptable cancer risk range based on exposure to
individual Aroclors through consumption offish tissue. Cancer risk estimates based on
Total PCB Congeners (i.e., 4x10~3) exceeded the EPA's acceptable cancer risk range.
In addition, the calculated non-cancer HI exceeded the acceptable threshold of 1.0, with
Aroclor-1254 (i.e., HQ = 9.3) identified as a COC with a HQ exceeding 1.0.
Risk Characterization Results for the Child Recreational User
Cancer Risks for Child Recreational Users - Individual Aroclors
Location: Dc
Scenario Tir
Receptor Pc
Receptor Ac
>nna Reservoir and Canal System (DRCS)
rieframe: Current/Future
pulation: Recreational User
e: Child
Medium
Exposure
Medium
Exposure
Point
Chemical
Cancer Risk
Ingestion
Dermal
Exposure
Inhalation | Routes Total
Surface
Water
Fish
DRCS
Aroclor-1254
3.2E-05
__
I 3.2E-05
Aroclor-1260
1.7E-05
—
1.7E-05
(Total)
4.9E-05
—
| 4.9E-05
Total Risk Across Fish | 5E-05
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Cancer Risks for Child Recreational Users - Total PCB Congeners
Location: Dc
Scenario Tir
Receptor Pc
Receptor Ac
>nna Reservoir and Canal System (DRCS)
rieframe: Current/Future
pulation: Recreational User
e: Child
Medium
Exposure
Medium
Exposure
Point
Chemical
Cancer Risk
Ingestion
Dermal
Exposure
Inhalation | Routes Total
Surface
Water
Fish
DRCS
PCB Congeners
2.2E-03
—
I 2.2E-03
(Total)
2.2E-03
—
I 2.2E-03
Total Risk Across Fish | 2E-03
Non-Cancer Hazards for Child Recreational Users
Location: Donna Reservoir and Canal System (DRCS)
Scenario Timeframe: Current/Future
Receptor Population: Recreational User
Receptor Age: Child
Medium
Exposure
Medium
Exposure
Point
Chemical
Non-Cancer Hazard Quotient
Primary
Target Organ
Ingestion
Dermal
Exposure
Inhalation | Routes Total
Surface
Water
Fish
DRCS
Aroclor-1254
Skin
19
—
I 19
Aroclor-1260
NA
—
—
..
(Total)
19
—
I 19
Total Hazard Index Across Fish
| 19
As shown in the risk characterization table for the child recreational user, the cancer risk
estimate for the child recreational user (i.e., 5x10~5) was within the EPA's acceptable
cancer risk range based on exposure to individual Aroclors through consumption offish
tissue. Cancer risk estimates based on Total PCB Congeners (i.e., 2x10~3) exceeded
the EPA's acceptable cancer risk range. In addition, the calculated non-cancer HI
exceeded the acceptable threshold of 1.0, with Aroclor-1254 (i.e., HQ=19) identified as
a COC with a HQ exceeding 1.0.
Uncertainties in the Human Health Risk Assessment
There are numerous uncertainties involved in the HHRA process. The HHRAforthe
Site identified the following as sources of potential uncertainty related to the risk
assessment:
• Evaluation of dioxin-like PCB Congeners was not included in the overall
quantitative evaluation of PCB-related risks. A separate quantitative evaluation,
conducted as part of the HHRA uncertainty section, was performed. This
evaluation demonstrated that Total PCB Congener risks were higher; although,
concentrations of dioxin-like PCB Congeners in fish tissue do have the potential
to pose unacceptable cancer and non-cancer risks. Therefore, any remedial
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actions or risk management decisions made to address risks from Total PCBs
would also address risks posed by the dioxin-like PCB Congeners.
• The field sampling plan can have a significant impact on the results obtained in
calculating human health risks at a site. Samples collected within the reservoir
and canal system were collected from separate exposure areas that span the
entire length of the Site. As a result, this reduces the uncertainties associated
with biased sampling. Additionally, samples for various media were also collected
for several years. The number of samples and variance in the sample collection
times aid in the statistical evaluation of EPCs. Uncertainties associated with
sampling and analyses are expected to be low.
• Specific canal segments along the reservoir and canal system revealed higher
levels of PCBs in sediment; however, the evaluation offish tissue results was
based upon the collection offish tissue along the entire reservoir and canal
system. This decision was made due to the mobility offish across the system
and because fishers are expected to use the entire reservoir and canal system
and not only collect fish from isolated areas for long periods of time. Fish
collected from areas with higher concentrations of PCBs in sediment may have
the potential to pose higher risks for fishers, but the entire reservoir and canal
system presents potential human health risk concerns from the consumption of
fish.
• In circumstances where the frequency of detection is low it becomes challenging
to perform the necessary statistics to calculate an EPC, and the results are
considered unreliable. Therefore, for chemicals with a low frequency of detection,
the maximum detected concentration was used as the EPC. This can result in an
overestimate of potential risks when evaluating long term exposures.
• Much of the toxicological information comes from experiments with laboratory
animals. Experimental animal data have been relied on by regulatory agencies to
assess the hazards of chemical exposures to humans. Interspecies differences in
chemical absorption, metabolism, excretion, and toxic response are not well
understood; therefore, conservative assumptions are applied to animal data
when extrapolating to humans. In general, conservative assumptions are made
throughout the toxicity assessment, which can result in an overestimate of risk.
• Much of the toxicological information for carcinogenic assessments comes from
experiments with laboratory animals. There is uncertainty about whether animal
carcinogens are also carcinogenic in humans. While many chemical substances
are carcinogenic in one or more animal species, only a very small number of
chemical substances are known to be human carcinogens. The fact that some
chemicals are carcinogenic in some animal species, but not in others, raises the
possibility that not all animal carcinogens are human carcinogens. Regulatory
agencies assume that humans are as sensitive to carcinogens as the most
sensitive animal species. This policy decision, designed to prevent
underestimation of risk, introduces the potential to overestimate carcinogenic
risk.
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• Differences in individual human susceptibilities to the effects of chemical
exposures may be caused by such variables as genetic factors (e.g., glucose-6-
phosphate dehydrogenase deficiency), lifestyle (e.g., cigarette smoking and
alcohol consumption), age, hormonal status (e.g., pregnancy), and disease. To
account for the diversity of human populations and their differing susceptibilities
to chemically induced injury or disease, a safety factor is used. The EPA uses a
factor between 1 and 10, and this uncertainty may lead to overestimates of
human health effects at given doses.
• When experimental data available on one route of administration are different
from the actual route of exposure that is of interest, route-to-route extrapolation
must be performed before the risk can be assessed. Several criteria must be
satisfied before route-to-route extrapolation can be undertaken. The most critical
assumption is that a chemical injures the same organ(s) regardless of route,
even though the injury can vary in degree. Another assumption is that the
behavior of a substance in the body is similar by all routes of contact. This may
not be the case when, for example, materials absorbed via the gastrointestinal
tract pass through the liver prior to reaching the systemic circulation, whereas by
inhalation the same chemical will reach other organs before the liver. However,
when data are limited, these extrapolations are made and may result in
overestimates of human toxicity.
Conclusions of the Human Health Risk Assessment
The HHRA identified potential concerns for human health from the consumption offish
collected from the reservoir and canal system. The HHRA results reveal that if no
remedial action or other means of control is taken, there is a potential for an increased
probability of cancer for adult recreational users above the EPA's acceptable cancer risk
range, including a potential for systemic non-cancer effects to all recreational receptors.
Direct contact with other potentially affected media (i.e., soil, surface water, and
sediment), which includes the consumption of produce from the surrounding agricultural
fields and consumption of drinking water from the reservoir and canal system, does not
pose unacceptable human health concerns. Based on the results of the HHRA, Aroclor-
1254, Aroclor-1260, and Total PCB Congeners have been identified as the only Site-
related human health COCs for the consumption offish.
2.7,2 Summary of the Ecological Risk Assessment
An ERA was completed to characterize and quantify potential environmental impacts to
ecological receptors from chemicals in soil, sediment, surface water, and fish at the Site
(EA 2016c). The ERA initially used conservative assumptions regarding exposure and
toxicity to develop a CSM and identify contaminants of potential concern (COPCs). The
preliminary results based on these conservative assumptions represent maximum
estimates of risk, and are not necessarily representative of population-wide risks;
therefore, additional data evaluation and risk characterization that relied on Site-specific
information was conducted to calculate more realistic and receptor-specific risk
estimates to draw conclusions.
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Exposure Assessment
For the ERA, the Site was divided into five separate exposure areas based on potential
sources of contamination, habitat, and hydraulic connectivity. Figure 23 (Ecological
Exposure Areas) of this ROD depicts the exposure areas that were used to group data
for evaluation in the ERA. Section 2.5 (Site Characteristics) of this ROD provides a
description of the vegetation, fish, and birds that may potentially be present the Site.
Ecological Receptors and Representative Receptor Species
Based on the ecological setting and media of concern discussed in Section 2.5 (Site
Characteristics) of this ROD, ecological receptors potentially present at the Site include
plants, soil invertebrates, wildlife (i.e., birds and mammals), benthic invertebrates,
aquatic organisms, reptiles, and amphibians.
Specific receptor groups and representative receptor species were selected to
represent each of the ecological resource categories identified at the Site. Selection of
representative receptor species is based primarily on several factors: 1) the likelihood
of a species to use the Site and the area immediately surrounding the Site, 2) the
potential for exposure to Site-related contaminants based on the feeding habits and life
history of the organisms/guild represented by the receptor species, 3) the availability of
life history and exposure information for the selected receptor species, and 4) the
availability of toxicity information for the representative receptor species. Representative
receptor species selected and evaluated in the ERA included the following:
• Terrestrial plants - multiple species
• Soil invertebrates - earthworm
• Terrestrial herbivorous birds - northern bobwhite (Colinus virginianus)
• Terrestrial omnivorous birds - American robin (Turdus migratorius)
• Predatory birds - red-tailed hawk (Buteo jamaicensis)
• Terrestrial herbivorous mammals - white-footed mouse (Peromyscus leucopus)
• Terrestrial insectivorous mammals - least shrew (Cryptotis parva)
• Predatory mammals - coyote (Canis latrans)
• Aquatic herbivorous birds - Canada goose (Branta canadensis)
• Aquatic insectivorous birds - laughing gull (Egretta thula)
• Small piscivorous birds - belted kingfisher (Megaceryle alcyon)
• Large piscivorous birds - great blue heron (Ardea herodias)
• Aquatic herbivorous mammals - nutria (Myocaster coypus)
• Aquatic carnivorous mammals - raccoon (Procyon lotor)
• Piscivorous mammals - river otter (Lutra canadensis)
• Benthic invertebrates - multiple species
• Aquatic organisms - multiple species
• Amphibians - American bullfrog (Rana catesbeiana)
• Reptiles - diamondback water snake (Nerodia rhombifer)
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Measurement endpoints selected to complete the ERA are presented in Table 1
(Measurement Endpoints for Ecological Risk Assessment). The CSM used in the ERA
is presented in Figure 24 (Ecological Conceptual Site Model).
Threatened and Endangered Species
The Texas Parks and Wildlife Department Texas Natural Diversity Database was used
as a source to determine the list of threatened and endangered species likely to be
present at the Site. In the absence of a Site-specific wildlife survey, the ERA made the
conservative assumption that any threatened or endangered species that could occur
within Hidalgo County could be present at the Site.
Several T&E species were evaluated during the ecological risk assessment. These T&E
species included the Coues' rice rat, interior least tern, reddish egret, false spike
mussel, Salina mucket, and Texas hornshell. Some or all of these species may or may
not be present at the Site because of limited habitat. According to the Texas Parks and
Wildlife the Coues' rice rat prefers habitat in cattail-bulrush marshes and aquatic grassy
zones near oxbow lakes. From aerial photographs, the Northwest Reservoir appears to
be the remnants of an oxbow lake; however, this portion of the reservoir system
comprises a relatively small area in comparison to the entire reservoir and canal
system. The canals are not a suitable habitat for this T&E species.
For each species that may be present, a surrogate receptor was identified and carried
through the ERA. The following receptors were identified as surrogate receptors for at
least one T&E species: American robin, red-tailed hawk, least shrew, coyote, laughing
gull, belted kingfisher, great blue heron, raccoon, multiple species of benthic
invertebrates, multiple species of aquatic organisms, American bullfrog, and the
diamond backwater snake (Table 2 - Threatened and Endangered Species that may
be found in Hidalgo County).
Identification of Chemicals of Potential Concern
The ERA evaluated samples collected from the Site to identify COPCs in Site media.
Samples evaluated in the ERA included surface water, sediment, soil, fish tissue, and
mollusk tissue. COPCs were selected by comparison of maximum detected
concentrations found in Site media within each exposure area to conservative
ecological risk screening values. Chemicals with concentrations that equaled or
exceeded screening values were retained as COPCs. Chemicals that lacked media-
specific screening criteria were also retained as COPCs for further evaluation.
Chemicals with maximum concentrations that were below screening values were
dismissed from further consideration. The COPC screening tables for each area
identified in Figure 23 (Ecological Exposure Areas) are presented in Appendix B
(Selection of Chemicals of Potential Concern).
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Ecological Risk Characterization
COPCs initially identified in the ERA were evaluated using a combination of direct
exposure, uptake, and food web models that incorporated receptor-specific toxicity
reference values, exposure factors, and conservative assumptions to calculate potential
risks based on contaminant concentrations detected in Site media. Results of the initial
evaluation identified potential risks to several receptors because of exposure to
chemicals detected in Site media. Further evaluation of the results considered additional
Site-specific information including spatial extent, magnitude of exceedance, and fate
and transport information to refine the results and determine if further action was
required to mitigate potential ecological risks. A complete discussion of the risk
characterization is presented in the ERA (EA 2016c). Based on the results of this
analysis, PCBs were retained as the only Site-related ecological COCs requiring further
action. Acceptable ecological risks were found for Exposure Area 1 (Upstream of the
Siphon) and Exposure Area 2 (Arroyo Colorado). The following table provides a
summary of potentially unacceptable ecological risks identified by the ERA in the
remaining exposure areas (EA 2016c).
Summary of Potential Risks Identified by the Ecological Risk Assessment
Exposure Area
Receptor
Media
Chemical of Concern
3: LWMCU at Siphon Exit
Small Piscivorous Birds
Fish Tissue
Total PCB Congeners
Piscivorous Mammals
Fish Tissue
Total PCB Congeners,
Total PCB Aroclors
Benthic Invertebrates
Sediment
Aroclor-1254,
Total PCB Congeners,
Total PCB Aroclors
Threatened and Endangered Species
Interior Least Tern
Fish Tissue
Aroclor-1254,
Total PCB Congeners,
Total PCB Aroclors
Reddish Egret
Fish Tissue
Total PCB Congeners
Coues' Rice Rat
Sediment via ingestion of
benthos
Aroclor-1242, Aroclor-1260,
Total PCB Congeners,
Total PCB Aroclors,
False Spike Mussel, Salina
Mucket, and Texas Hornshell
Sediment
Aroclor-1242, Aroclor-1254,
Aroclor-1260,
Total PCB Congeners,
Total PCB Aroclors
4: LWMCU Downstream
of the Siphon
Small Piscivorous Birds
Fish Tissue
Total PCB Congeners
Piscivorous Mammals
Fish Tissue
Total PCB Congeners,
Total PCB Aroclors
Threatened and Endangered Species
Interior Least Tern
Fish Tissue
Aroclor-1254,
Total PCB Congeners,
Total PCB Aroclors
Reddish Egret
Fish Tissue
Total PCB Congeners
Coues' Rice Rat
Benthos Tissue
Total PCB Congeners,
Total PCB Aroclors
5: Lined Canals, Reservoirs,
and Soil
Threatened and Endangered Species
Coues' Rice Rat
Sediment via ingestion of
benthos
Total PCB Congeners,
Total PCB Aroclors
Note:
There is uncertainty associated with threatened and endangered species, for which little data are available regarding their actual
presence at the Site.
LWMCU - Lower West Main Canal Unlined
PCB - Polychlorinated Biphenyls
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Conclusions of the Ecological Risk Assessment
The ERA evaluated risk based on exposure groupings; however, a single set of
ecological Preliminary Remediation Goals (PRGs) was developed to ensure
consistency in risk management actions applicable across the entire Site. The ERA
determined that benthic invertebrates, piscivorous mammals, small piscivorous birds,
and several T&E species (i.e., interior least tern, reddish egret, Coues' rice rat, false
spike mussel, Salina mucket, and Texas hornshell) represented the most sensitive
receptors evaluated for effects from PCBs. Therefore, PRG development focuses on
these receptors. Risk-based thresholds of effects were developed for use as risk-based
PRGs for sediment. Background was not considered because PCBs are anthropogenic
and were detected in very few samples upstream of the Siphon.
A summary of the potential PRGs for ecological receptors determined, during the FS, is
provided in the following table.
Potential Ecological Preliminary Remediation Goals
Chemical of
Concern
Receptor
Sediment
Preliminary
Remediation Goal
(mg/kg)
Note
Total PCBs
Small Piscivorous Birds
General Population
0.483
NOAEL-LOAEL midpoint. Intended for
application as a reach-wide average.
Total PCBs
Piscivorous Mammals
General Population
0.071
NOAEL-LOAEL midpoint. Intended for
application as a reach-wide average.
Total PCBs
Benthic Invertebrates
General Population
0.68
Probable Effect Concentration. Intended for
application on a point-by-point basis or as an
average across small areas.
Total PCBs
Interior Least Tern
0.088
NOAEL. Intended for application on a point-by-
point basis.
Total PCBs
Reddish Egret
0.088
NOAEL. Intended for application on a point-by-
point basis.
Total PCBs
Coues' Rice Rat
0.023
NOAEL. Intended for application on a point-by
point basis, applicable to the reservoir only.
Reservoir is already in compliance.
Total PCBs
False Spike Mussel,
Salina Mucket,
Texas Hornshell
0.06
Threshold Effects Concentration. Intended for
application on a point-by-point basis or as an
average across small areas.
Note:
LOAEL - lowest observed adverse effect level
mg/kg - milligrams per kilogram (dry weight)
NOAEL - no observed adverse effect level
Total PCBs - Either the sum of polychlorinated biphenyls (PCBs) as Aroclors or the sum of individual PCB
congeners.
Lowest Sediment Ecological Preliminary Remediation Goal
The sediment PRG for the Coues' rice rat of 0.023 mg/kg Total PCBs is the lowest of all
ecological PRGs, and thus would drive remediation. Given that the presence of the
Coues' rice rat has not been established for the Site, it is important to consider habitat
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and which areas of the Site this receptor may utilize. According to the TPWD, the
habitat preference for the Coues' rice rat is cattail-bulrush marsh and aquatic, grassy
zones near oxbow lakes. The only portions of the reservoir and canal system that
supports comparable habitat are portions of the reservoir, which include some areas of
emergent vegetation and forested wetlands. None of the samples collected from the
reservoir exceeded the sediment ecological PRG of 0.023 mg/kg Total PCBs (i.e., the
highest detection was 0.014 mg/kg) and thus the reservoir does not require risk
management for ecological receptors.
The canals do not provide habitat consistent with the needs of the Coues' rice rat. Most
of the shoreline along the 7.6 miles of canal is highly disturbed. A total of 3.5 miles is
lined with concrete and does not provide vegetative habitat that would support use by
the species. Of the remaining 4.1 miles that are unlined, habitat consists of a grassy
strip of fragmented shoreline vegetation between the canal and access roads. The
shorelines are steep and support a marsh border of less than 1 to 3 feet. Several areas
of shoreline vegetation are dominated by giant reed (i.e., Phragmites australis), an
invasive species. Based on this information, the canals provide habitat that is largely
inconsistent with Coues' rice rat habitat preferences. Therefore, the ecological PRG of
0.023 mg/kg has not been applied to sediment in the canals in favor of goals for species
that may actually be present.
2.7,3 Basis for Action
The response action selected in this ROD is necessary to protect human health and the
environment from actual or threatened releases of hazardous substances into the
environment. The Selected Remedy is warranted because the HHRA determined that
exposure to PCBs through consumption offish poses unacceptable human health
cancer risks and non-cancer hazards. Reducing PCB levels in fish and preventing
consumption of contaminated fish are two ways to reduce risk. To reduce PCB levels in
fish, it is necessary to reduce PCB levels in sediment (i.e., canal dredging/excavation)
and mitigate releases of contaminants from the likely source of PCBs (i.e., the Siphon).
The ERA identified potential concerns for ecological receptors. Meeting the human
health Cleanup Level for sediment will also address the lowest applicable sediment
PRG for ecological receptors, including the Texas Risk Reduction Program Sediment
Protective Concentration Levels established pursuant to 30 Texas Administrative Code
305.75.
2.8 REMEDIAL ACTION OBJECTIVES
The Remedial Action Objectives (RAOs) for the Site describe what the proposed Site
cleanup is expected to accomplish. According to the NCP, 40 CFR §300.430(a)(1)(i),
the ". . . national goal of the remedy selection process is to select remedies that are
protective of human health and the environment, that maintain protection over time, and
that minimize untreated waste." Cleanup Levels (CULs) and Remediation Goals (RGs)
are contaminant-specific concentrations used to measure the success of the Selected
Remedy in meeting the RAOs during and after the implementation of the remedy.
Based on the information relating to the types of contaminants, environmental media of
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concern, and potential exposure pathways, the following Site-specific RAOs, CULs, and
RGs were developed:
RAO 1: Reduce the long-term human health cancer risks and the non-cancer hazards
from human consumption of Site fish contaminated with PCBs. This goal will be
achieved by reducing the concentrations of PCBs in sediment downstream from the
likely source (i.e., the Siphon) and mitigating the transport pathway from the Siphon into
the Site.
• Sediment CUL - The long-term objective will be achieved by reducing the
concentration of PCBs in sediment, downstream of the Siphon's exit, to less than
0.043 mg/kg Total PCBs. This will achieve a Site-wide acceptable risk level of
10"5 adult recreational user cancer risk and a child recreational user HI of 1 from
the consumption of fish.
• Fish Tissue RG - The long-term objective will also be achieved by reducing the
concentration of PCBs in fish tissue, throughout the reservoir and canal system,
to less than 0.031 mg/kg Total PCBs. Progress toward this objective will be
measured by performing statistical analyses offish tissue.
RAO 2: Reduce the short-term human health cancer risks and the non-cancer hazards
from human consumption of Site fish contaminated with PCBs.
• The short-term objective will be achieved by reducing or removing the fish from
the Site possibly contaminated with PCBs and available for human consumption.
Progress toward this objective will be measured by the number, species, and
size of the fish removed from the reservoir and canal system. Fish tissue will also
be monitored for the concentrations of Total PCBs described under RAO 1.
RAO 3: Reduce the risks to ecological receptors (i.e., small piscivorous birds,
piscivorous mammals, benthic invertebrates, and threatened/endangered species) from
exposure to PCBs in sediment.
• Reducing the concentration of PCBs in sediment, downstream of the Siphon's
exit, to less than 0.043 mg/kg Total PCBs will also be protective of ecological
receptors.
Reducing the exposure of human and ecological receptors of concern to PCBs will
mitigate Site baseline risks identified in the HHRA and ERA, as discussed in Section 2.7
(Summary of Site Risks) of this ROD. The quantitative RG and CUL that need to be met
to achieve the RAOs are presented in the following table and are further discussed in
the following sections of this ROD.
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Chemicals of Concern and Remediation Goal and Cleanup Level
Chemical of Concern
Media
Remediation
Goal and
Cleanup
Level
Basis for Remediation Goal
and Cleanup Level
Total PCBs
Fish Tissue
RG
0.031 mg/kg1
Calculated human health risk-based value
Total PCBs
Sediment
CUL
0.043 mg/kg2
Calculated human health risk-based value
Note:
1 This concentration corresponds to an Aroclor-1254 child recreational user non-cancer HI of 1.
2 This concentration is also protective of the ecological receptors of concern,
mg/kg - milligrams per kilogram
RG - Remediation Goal
CUL - Cleanup Level
Total PCBs - The sum of polychlorinated biphenyls measured as either Aroclors or Congeners
2.8.1 Human Health Remediation Goal and Cleanup Level
Risk results from the HHRA were reviewed to determine a fish tissue RG and sediment
CUL for the Site. Aroclor-1254, Aroclor-1260, and Total PCB Congeners were identified
as COCs for recreational users from the ingestion offish tissue. Determination of a fish
tissue RG is based upon both the PCB cancer slope factors and the exposure
parameters presented for each receptor in the HHRA (EA 2016b). Cancer slope factors
for both the Aroclors and Total PCB Congeners were assumed a "high risk" PCB at 2.0
mg/kg-day. Non-cancer reference doses are only set forth for Aroclor-1254. The
selected RG of 0.031 mg/kg Total PCBs in fish tissue will meet a recreational fisher
exposure scenario noncancer HI of 1, which is below a recreational fisher exposure
scenario cancer risk level of 10~5 (i.e., 0.041 mg/kg Total PCBs).
Sediment is a primary source of PCBs at the Site that results in fish PCB body burdens
which are taken up through the food web into fish. Site-specific bioaccumulation factors
were determined to derive a sediment CUL protective of human receptors from the
ingestion offish. Bioaccumulation factors are the ratio of PCBs in fish fillets to the
concentration in sediment at a steady state, where the organism can take in the
contaminant through ingestion of its food as well as through direct contact. The Site-
specific bioaccumulation factor for fish fillets is 9.54 mg/kg wet weight organism/mg/kg
dry weight sediment. Sediment cleanup goals were then calculated with the Site-specific
bioaccumulation factor based on targeted fish tissue concentrations. The resulting Total
PCB sediment CUL is 0.043 mg/kg.
An analysis of the PCB concentrations in sediment across the reservoir and canal
system was completed assuming the removal of the sediment locations that exceed the
CUL of 0.043 mg/kg Total PCBs. The resulting overall 95 percent upper confidence limit
(95% UCL) was determined to be 0.00276 mg/kg Total PCBs in the remaining
sediment. This concentration would theoretically, with time, result in fish tissue
concentrations below the RG of 0.031 mg/kg Total PCBs for fish tissue. This long-term
objective will be achieved by reducing the concentration of PCBs in fish tissue,
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throughout the reservoir and canal system, to less than 0.031 mg/kg Total PCBs. The
95% UCL, or other statistical parameter(s), will be used to measure the attainment of
this RG. The sampling frequency and the period to achieve this objective will be
determined during the remedial design of the Selected Remedy.
A statistical analysis of the PCB concentrations in sediment across the reservoir and
canal system, assuming removal of the sediment locations that exceed a concentration
of 0.043 mg/kg Total PCBs, results in a Site-wide sediment concentration below the 10"5
adult recreational user cancer risk level and the Aroclor-1254 child recreational user
non-cancer HI of 1. The statistical analysis of the PCB concentrations in remaining
sediment across the reservoir and canal system, after removal of the sediment locations
that exceed a CUL of 0.043 mg/kg, results in an overall 95% UCL of 0.00276 mg/kg
Total PCBs in sediment. This concentration is below the calculated sediment CUL
based on, 1) a 10"5 adult recreational user cancer risk level corresponding to 0.004
mg/kg, and 2) an Aroclor-1254 child recreational user non-cancer HI of 1 corresponding
to 0.003 mg/kg. The 95% UCL provides reasonable confidence that the true Site
average will not be underestimated. An estimate of average concentration is used
because: 1) carcinogenic and chronic non-carcinogenic toxicity criteria are based on
lifetime average exposures, and 2) an average concentration is most representative of
the concentration that would be contacted at the Site over time by both human and
ecological receptors.
During the remedial process a concentration equivalent to a lifetime cancer risk of 10"6
is first established as a point of departure and then other factors are considered to
determine where within the acceptable risk range of 10~4 to 10~6 a CUL(s) or RG(s) for a
given contaminant at a specific site should be established. The EPA is proposing a
departure from a cleanup goal of 10~6 for this Site based on: 1) consistency with the
Texas Risk Reduction Program (TRRP), which is also cost effective, and 2) existing Site
soil and sediment PCB concentrations.
A chemical-specific cancer risk of 10"5 was chosen because the future anticipated reuse
for the Site is recreational, and this risk level is consistent with the TRRP risk level of
10"5 (Title 30 Texas Administrative Code Chapter 350.74). To be consistent with the
TRRP risk level, the target risk value for the Site moved away from the point of
departure of 10"6 and is within the target risk range of 10"4 to 10"6 specified by the NCP.
A human health risk level of 10~5 and an HI of 1 are achievable at this Site. The ability to
achieve a 10"6 risk level may not be possible because of non-Site related influences of
PCBs and the extremely low sediment concentration that would be necessary in order
to achieve a 10"6 risk level (0.0004 mg/kg). Soil samples collected from 10 of 41
locations meet or exceed 0.004 mg/kg Total PCB Aroclors or Total PCB Congeners.
Three soil samples were taken from the banks of the Lower West Main Canal Unlined,
five from the banks of the Arroyo Colorado River, and two near irrigation risers in
adjacent agricultural fields. PCBs in the Arroyo Colorado River exposure area are not
considered to be Site-related. The maximum detected Total PCB concentration in the
soil of the Arroyo Colorado was 0.013 mg/kg which is more than 3 times the sediment
concentration of 0.004 mg/kg corresponding to a 10~5 cancer risk level. Concentrations
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of Total PCB Congeners in the Arroyo Colorado River soil range from 0.0007 to 0.013
mg/kg with an arithmetic average of 0.004 mg/kg. Soil with concentrations above
0.004 mg/kg may become airborne and deposited in the reservoir and canal system and
may complicate attempts to reach sediment levels of 0.004 mg/kg, including the
sediment level of 0.0004 mg/kg (which is the sediment concentration corresponding to a
10~6 cancer risk level), by serving as a residual source of contamination. Five sediment
samples collected upgradient of the Siphon meet or exceed 0.004 mg/kg Total PCBs in
sediment. These soil and sediment concentrations are not Site-related and are
expected to represent background concentrations.
2.8.2 Ecological Preliminary Remediation Goal
A potential sediment ecological PRG of 0.023 mg/kg for Total PCBs was developed
during the FS. The most sensitive ecological receptor determined during the ERA was
the Coues' rice rat, which may or may not exist at the reservoirs. An analysis of the PCB
concentrations in sediment across the reservoir and canal system was completed
assuming the removal of the sediment locations that exceed the CUL of 0.043 mg/kg
Total PCBs. The resulting overall 95% UCL was determined to be 0.00276 mg/kg Total
PCBs in the remaining sediment. Therefore, the selection of the CUL for sediment will
also be protective of ecological receptors. The ERA determined that benthic
invertebrates, piscivorous mammals, small piscivorous birds, and threatened and
endangered species (i.e., interior least tern, reddish egret, Coues' rice rat, false spike
mussel, Salina mucket, and Texas hornshell) represented the sensitive ecological
receptors evaluated for effects from PCBs (EA 2016c).
2.9 DESCRIPTION OF ALTERNATIVES
Remedial alternatives were developed using general response actions and technologies
retained following the screening process presented in the FS (EA 2016d). Remedial
alternative components were developed based on the media that they are designed to
treat. The following two remedial alternative components were developed for the Siphon
to remediate the likely source of PCBs at the Site:
1. Sliplining of the Siphon, and
2. Replacement of the Siphon.
The following three remedial alternative components were developed in the FS (EA
2016d) to remediate the impacted sediment downstream of the Siphon's exit:
1. Canal Dredging,
2. Canal Dredging and Reservoir Monitored Natural Recovery, and
3. Canal Dredging, Reservoir Dredging, and Reservoir Capping.
The following eight remedial alternatives were assembled based upon the remedial
alternative components previously listed:
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• Alternative 1 - No Further Action.
• Alternative 2 - Limited Action.
• Alternative 3 - Slipline Siphon, Canal Dredging, and Fish Removals.
• Alternative 4 - Slipline Siphon, Canal Dredging, and Reservoir Monitored Natural
Recovery.
• Alternative 5 - Slipline Siphon, Canal Dredging, and Reservoir Dredging with
Sand Layer.
• Alternative 6 - Replace Siphon, Canal Dredging, and Fish Removals.
• Alternative 7 - Replace Siphon, Canal Dredging, and Reservoir Monitored
Natural Recovery.
• Alternative 8 - Replace Siphon, Canal Dredging, and Reservoir Dredging with
Sand Layer.
Alternatives 1,2,3, and 6 were the only alternatives retained after they were screened
for effectiveness, implementability, and cost. Summaries of the retained alternatives and
approximate costs are provided in the following sections of this ROD.
2.9.1 Alternative 1: No Further Action
Estimated Time for Design/Construction: Not applicable
Estimated Time to Reach Remediation Goals: Not applicable
Estimated Capital Costs: $0
Estimated Lifetime O&M Costs: $0
Estimate Total Present Worth Costs: $0
Discount Rate: Not applicable
Number of Years Costs are Projected: Not applicable
As required by the NCP, 40 CFR § 300.430 (e)(6), the evaluation of alternatives must
include a No Further Action (NFA) Alternative. This alternative is used as the baseline
alternative against which the effectiveness of all other remedial alternatives is
evaluated. Under this alternative, the EPA would take no further action and the
contaminants would remain in place and would be subject to environmental influences.
No further attempts would be made to reduce the PCB concentrations in fish and
sediment or limit consumption offish with unacceptable levels of PCBs. Additionally, no
attempts would be made to slipline/replace the Siphon or remove fish contaminated with
PCBs from the Site. Furthermore, no action would be taken to prevent unauthorized
access and no institutional controls to inform interested parties regarding the Site
conditions would be implemented.
2.9.2 Alternative 2: Limited Action
Estimated Time for Design/Construction: Not applicable
Estimated Time to Reach Remediation Goals: Not applicable
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Estimated Capital Costs: $8,000
Estimated Lifetime O&M Costs: $1,630,000
Estimate Total Present Worth Costs: $1,640,000
Discount Rate: 7%
Number of Years Costs are Projected: 30 Years
Alternative 2 (i.e., Limited Action) includes community involvement and institutional
controls. Community involvement activities would be performed only as needed for the
duration of the remedial action, and would rely on partnerships with state (i.e., TDSHS
and TPWD), city (i.e., Cities of Donna and Alamo), and other local entities (i.e., Irrigation
District and Hidalgo County [Precincts 1 and 2]), as well as community-based
organizations, to develop activities and measures to reduce the public's exposure to fish
from the Site.
An institutional control, in the form of a land-use restriction or notice as to the
environmental conditions of the property, would be required. The institutional control
could consist of either a restrictive covenant or a deed notice. The requirements for
filing land use restrictions in the State of Texas are specified in "30 Texas Administrative
Code Chapter 350 Subchapter F." A restrictive covenant, or deed notice, is an
instrument filed in the real property records of the county where the affected property is
located. Additionally, the EPA would coordinate with the TDSHS to maintain the existing
Aquatic Life Order Number 9.
Under Alternative 2, no other actions would be taken (i.e., removal of fish or sediment,
sliplining or replacement of the Siphon, or performance monitoring offish and
sediment).
2.9.3 Alternative 3: Slipline Siphon, Canal Dredging, and Fish Removals
Estimated Time for Design/Construction: 14 Months (Design),
1 Months (Construction)
Estimated Time to Reach Remediation Goals: After Construction is Complete
(Sediment), 10 Years (Fish)
Estimated Capital Costs: $14,410,000
Estimated Lifetime O&M Costs: $1,150,000
Estimate Total Present Worth Costs: $15,600,000
Discount Rate: 7%
Number of Years Costs are Projected: 10 Years
Alternative 3 (i.e., Slipline Siphon, Canal Dredging/Excavation, and Fish Removals)
includes sliplining the Siphon, to mitigate the transport pathway from the likely PCB
source into the Site, and the dredging/excavation of PCB-contaminated sediment with
Total PCB concentrations above 0.043 mg/kg downstream of the Siphon's exit.
Alternative 3 would also include sediment sampling and monitoring downstream of the
Siphon's exit, up to five fish removals over a period of five years, fish tissue sampling,
community involvement activities for ten years, maintenance of engineering controls,
and the implementation of institutional controls.
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Sliplining the Siphon
Sliplining the Siphon would utilize a barrier between the interior wall of the Siphon and
the water that flows through it from the Main Canal to the Lower West Main Canal
Unlined to isolate contaminant migration pathways. Sliplining of existing pipelines is
typically used to restore the structural integrity of a pipeline and is accomplished by
installing a smaller pipe into the existing pipeline. The smaller pipe would be anchored
into the existing pipeline by filling the void space with grout. Upon completion, the
existing Siphon would no longer be in contact with water that flows through the reservoir
and canal system.
Prior to sliplining the Siphon, a structural evaluation of the Siphon would be performed.
The Siphon was constructed around 1927 and is probably approaching the end of its
design life. While sliplining will extend the life of the Siphon, it must withstand the
dewatering, uncovering, and slipline installation. It is possible that the concrete and
steel may have degraded over time and will not withstand the sliplining process. If the
Siphon were to collapse or fail during the sliplining process or after the remediation,
another alternative may have to be implemented.
To install the slipline into the Siphon, water in the Siphon would be removed and the
area would be prepared for construction activity (i.e. surveyed, cleared of brush, etc.).
Temporary cofferdams would be placed at the entrance and exit of the Siphon (i.e., in
the Main Canal and Lower West Main Canal Unlined, respectively), and the water would
bypass the Siphon through a series of pumps and a temporary pipeline. Centrifugal
pumps or similar equipment would be used to empty the water from the Siphon. There
would be complexities associated with the installation of a temporary bypass such as
obtaining the proper access and coordination with the entities which have jurisdiction
over the location of the bypass equipment. The fish in the Siphon at the time of
dewatering would be removed and properly disposed of.
After emptying the water from the Siphon, approximately seven temporary access
points would be created in areas where directional changes in the Siphon may occur to
insert the slipline. Constructing these access points would involve excavation of the
overlying material (e.g., soils) and demolition of the top of the Siphon to expose its
interior. If needed, access points near the Arroyo Colorado River would require
temporary diversion of the river. Cofferdams and dewatering pumps would be used to
access these areas. Once the Siphon is open, 20-foot lengths of 96-inch diameter
fiberglass reinforced pipe and pipe joints would be pushed into the Siphon. After each
segment of pipe is in its final position, the annular space between the Siphon and
slipline would be grouted in place. Once the slipline pipes have been installed and
anchored, water flow through the Siphon could resume. Although the diameter of the
Siphon would be narrowed, the capacity of flow would not be reduced. The friction loss
in a fiberglass slipline compared to a concrete pipe would compensate for the reduction
of cross sectional area. The estimated length of time required for bypassing the Siphon
would be approximately two weeks.
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Post slipline installation activities would include backfilling, grading, and planting native
vegetation at the temporary access points to prevent erosion in the area. The entire
construction phase of the Slipline Siphon component is estimated to take approximately
two months to complete.
Sediment sampling would be completed to evaluate the effectiveness of the slipline.
Sediment samples would be collected directly downstream of the Siphon's exit,
analyzed for Total PCBs, and the results for Total PCBs would be compared to the
sediment CUL.
Canal Dredging
The area of remediation under Alternative 3, required to meet the sediment CUL of
0.043 mg/kg Total PCBs, spans the width of the Lower West Main Canal Unlined
approximately 4,500 feet beyond the Siphon's exit (i.e., an area approximately 55 feet
wide by 4,500 feet in length) as shown in Figure 25 (Sediment Remediation Area Based
on a Sediment Cleanup Goal of 0.043 mg/kg). Approximately 20 inches of sediment
would be mechanically dredged/excavated from the canal using clamshell excavation
methods or similar equipment. A volume of approximately 20,000 cubic yards of
sediment would be excavated from the canal, which accounts for approximately 6
inches of operator error during the removal.
During the dredging/excavation of canal sediment, a temporary bridge would be
installed adjacent to the existing bridge downstream of the Siphon's exit to allow the
agricultural equipment and vehicles to cross the canal during the remedial action.
During the remediation of the area, the bridge may be left in place without complicating
the remedy. To prevent migration of contamination into the water column and
downstream during sediment dredging/excavation activities, silt curtains would be
installed to capture the disturbed sediment. Dredging/excavation of the sediment during
low water conditions may not require the use of silt curtains. Contaminated material
would be partially dewatered on the Site using a series of watertight rolloffs and
fractionation tanks, and the sediment would be stabilized and transported to an
approved off-site disposal facility. Sediment would be sampled before disposal to
ensure compliance with waste disposal requirements. Prior to the restoration of the
remediation area, confirmation samples would be collected as necessary to ensure that
the remediation satisfies the RAOs for the Site. During remedial action construction, the
levees would be stabilized using imported material to protect against construction
activity and erosion that may occur.
The estimated construction time for this remedy component is five months, and at no
time during these activities would the canal system require shutdown.
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Fish Removals
Fish removals would be performed on an annual basis for five years to reduce the
exposure pathway to human receptors by removing fish from the reservoir and canal
system possibly contaminated with PCBs and which would be available for human
consumption. The EPA would consider additional fish removal efforts after the five-year
period to determine if additional fish removals should be performed based on whether
the RG for Total PCBs in fish tissue is being met. These fish removals would aid in
meeting the RAOs for fish tissue and would enhance the effectiveness of the Selected
Remedy by achieving the RGs for fish tissue concentration levels, especially in the
larger fish which bioaccumulate greater concentrations of PCBs through the food chain.
All areas of the Site will be considered when determining where to conduct fish
removals. Fish removals would be accomplished using electrofishing/electroshocking
methods. During periods where low water conditions exist at the Site, fish accumulate in
certain areas and could be removed using seine netting or other applicable methods.
Coordination with the Irrigation District would be required to anticipate low water
conditions and plan the fish removals. The fish would be collected in drums and
disposed of at an off-site disposal facility. Other fish removal methods (e.g., hoop, fyke,
and pound nets, etc.) could be used to supplement the removal efforts.
Fish Tissue Monitoring
Monitoring offish tissue concentrations would be performed to evaluate potential risks
to human health and attainment of the RG for fish tissue. Although the types, number,
and locations offish to be collected during performance monitoring would be
determined during the remedial design of the Selected Remedy, bottom feeders and
predatory fish could be collected from each of the following five established fish
collection areas:
• Main Canal - Near the Rio Grande Pump Station.
• Main Canal - Near the weir and the Siphon's entrance.
• Lower West Main Canal Unlined - Near the Siphon's exit.
• Lower West Main Canal Unlined - Near the bridge at FM 1493.
• West Reservoir.
Actual sampling would be determined during the remedial design phase of the Selected
Remedy; however, targeted fish could be a minimum of 8 inches in length and
processed into fillets in the field or by the laboratory for the analysis of Total PCBs.
Collection efforts could focus on the primary targeted species identified in the following
table; however, secondary targeted species could be collected if primary targeted
species are not available.
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Predator Species
Bottom Feeder Species
Primary
Primary
Largemouth Bass
Smallmouth Buffalo
• Secondary
• Secondary
Smallmouth Bass
Alligator Gar
Common Carp
Channel Catfish
Sediment Sampling
Sediment sampling of the canal system would be performed to evaluate the
performance of the remedy. The frequency of the sampling would be determined during
the remedial design of the remedy. Sediment samples collected from the canal system
would be analyzed for Total PCBs.
Performance Monitoring
Alternative 3 includes performance monitoring to evaluate whether the RAOs for the
Site are being met. Performance monitoring would also be conducted to ensure that the
remedy remains protective of human health and the environment. After the completion
of the remedy, protectiveness of the implemented remedy would be evaluated during
the Five-Year Reviews required by CERCLA for the Site.
Performance monitoring would occur for a period of time beginning with the collection of
baseline data. Monitoring would include performance standards related to remedy
implementation and would be developed during the remedial design of the remedy
described in the ROD. These performance standards, which would be incorporated into
design documents, would promote accountability and ensure that the remedy meets the
RAOs stated in the ROD.
Institutional Controls
Alternative 3 would continue and/or enhance the Institutional Controls (ICs) for the Site.
ICs are non-engineering instruments, such as administrative and/or legal controls, that
help minimize the potential for exposure to contaminants and/or protect the integrity of a
response action by limiting land or resource use. ICs also provide information and
notification to interested persons and communities about any residual contamination left
at a site and any restrictions because of the remaining contamination. ICs typically are
used in conjunction with engineering controls or measures.
The engineering controls considered at this Site, under Alternative 3, are: 1) Sliplining
the existing Siphon (i.e., the likely source of the PCBs), and 2) Removal and disposal of
the PCB-contaminated sediment located hydraulically downstream from the existing
Siphon's exit. The NCP emphasizes that ICs are meant to supplement engineering
controls. ICs can include instruments such as signs that are used to minimize access to
contaminated areas or areas that may pose a physical hazard. ICs and engineering
controls can be used to accomplish various remedial objectives and could be
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implemented in a series during this remedial action to provide protectiveness of human
health and the environment.
The following ICs would be implemented at the Site for ten years under Alternative 3:
• ICs, in the form of a land-use restriction or notice as to the environmental
conditions of the property, would be required that provides restrictions on or
notification of the modifications to the existing Siphon under Alternative 3 (i.e.,
sliplining the Siphon) and which would protect the integrity of the remedy under
Alternative 3. The IC would consist of either a restrictive covenant or a deed
notice. The requirements for filing land use restrictions in the State of Texas are
specified in "30 Texas Administrative Code Chapter 350 Subchapter F." A
restrictive covenant, or deed notice, is an instrument filed in the real property
records of the county where the affected property is located.
• Signs would be required which warn anglers of the risks associated with the
consumption offish from the Site.
• The existing Aquatic Life Order Number 9, issued by the TDH (predecessor of
the TDSHS), would need to remain in place until fish tissue levels are safe for
human consumption. Knowledge of the order would be enhanced with additional
community outreach to encourage greater awareness of the prohibitions
concerning the taking of all fish species from the Site until the concentrations of
Total PCBs in fish tissue reach protective concentrations corresponding to the
RGs specified in the ROD.
Public Outreach and Education
Alternative 3 would include a public outreach and educational program. To be
successful, this program would rely on partnerships with state (i.e., TDSHS, TPWD, and
others), city (i.e., Cities of Donna and Alamo, and other cities), and local entities (i.e.,
Irrigation District, Hidalgo County [Precincts 1 and 2], and other counties), as well as
community-based organizations, to develop activities and measures to reduce the
public's exposure to fish from the Site. Following are outreach and educational activities
and programs that could be considered for implementation at the Site:
• Warnings in English and Spanish printed on water or other utility bills, received
by the public, concerning consumption offish from the Site. These bills are
expected to reach a large portion of the nearby communities such as every
residence and business in Donna and Alamo, Texas.
• Support from community-based organizations such as non-governmental
organizations (NGOs), media, and community relations specialists to inform
people about the risk of consuming contaminated fish.
• Partnering with health fairs, community fairs, and state/local health departments
to provide educational materials and training in multiple languages.
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• Distribution of specific outreach materials and messages focused on women of
child-bearing age who consume fish as a part of their diet.
• Conduct outreach, in coordination with the TDSHS, to commercial fish market
owners to inform them about the risks of buying fish from unlicensed vendors.
• Inform anglers about the contaminated fish at the Site and the TDSHS'
enforceable Aquatic Life Order Number 9 which prohibits the taking of all species
of aquatic life from the Site.
• Coordinate enforcement efforts, of the TDSHS' Aquatic Life Order Number 9,
with the TPWD and appropriate law enforcement officials by notifying the
appropriate authorities of individuals accessing the Irrigation District's private
property.
• Reducing the potential risks posed by consumption of contaminated fish from the
Site by coordinating with the local communities to identify an alternate fishing
location(s) near the Site, routinely stock this nearby lake/reservoir, and advertise
the alternate fishing location.
Five-Year Reviews
Pursuant to CERCLA Section 121(c), 42 U.S.C. § 9621(a), Alternative 3 would require
statutory Five-Year Reviews since contaminants (i.e., PCBs) would be left on-Site
above levels that permit unrestricted use and unlimited exposure. Although the EPA
routinely evaluates the remedy, a formal review would occur every five years in the form
of a Five-Year Review Report where the EPA would evaluate the performance of the
remedy (i.e., protectiveness of human health and the environment, and effectiveness of
the ICs).
2.9.4 Alternative 6 (Selected Remedy): Replace Siphon, Canal Dredging, and
Fish Removals
Estimated Time for Design/Construction:
Estimated Time to Reach Remediation Goals:
Estimated Capital Costs:
Estimated Lifetime O&M Costs:
Estimated Total Present Worth Costs:
Discount Rate:
Number of Years Costs are Projected:
14 Months (Design),
9 Months (Construction)
After Construction is Complete
(Sediment), 10 Years (Fish)
$18,710,000
$700,000
$19,400,0003
7%
10 Years
Alternative 6 (i.e., the Selected Remedy) includes replacing the existing Siphon,
dredging/excavating sediment with Total PCB concentrations greater than 0.043 mg/kg
downstream of the Siphon's exit, annual fish removals, fish tissue monitoring,
3 The costs associated with the acquisition of land for the location of the replacement siphon or the
negotiation of land easements are not included in these cost estimates.
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community involvement activities for ten years, maintenance of engineering controls,
and ICs.
Replacement of the Existing Siphon
Replacement of the existing Siphon involves the construction of a new siphon to replace
the existing one and sealing (i.e., grouting in place) the existing Siphon. Because the
Irrigation District's canal system can only be inoperable for short periods of time, a new
siphon will be constructed adjacent to the existing one. The profile of the new siphon will
roughly follow the profile of the existing Siphon, which is displayed in Figure 3 (Existing
Siphon Plan, Profile, and Sections). The possible location for the replacement siphon is
included in Figure 26 (Siphon Replacement). The greatest challenges to the installation
occurs where the new siphon intersects the Arroyo Colorado River and land acquisition
for the siphon. The river would have to be temporarily diverted (e.g., cofferdams,
dewatering pumps, etc.) to allow for construction to be completed in an area adjacent to
the existing Siphon. This diversion would require coordination with Hidalgo County and
the IBWC. The area will be prepared for construction activities (i.e., surveyed, cleared of
brush, etc.) prior to the installation of the new siphon.
The new siphon will be built using 108-inch inner diameter pre-stressed concrete pipe
placed in a trench 15 to 20 feet below the surface of the ground. The Arroyo Colorado
River will be temporarily diverted with cofferdams and dewatering pumps to allow for
construction to be completed in this area.
In addition to a new siphon, approximately 200 feet of the north end of the Main Canal
and 400 feet of the south end of the Lower West Main Canal Unlined will require
modification to connect to the new siphon. The new canal segments will contain
concrete lining and transition to the new siphon's entrance and from the new siphon's
exit. A component of the Selected Remedy will require the construction of a new flow
control gate (i.e., weir) near the entrance of the siphon (Figure 26 - Siphon
Replacement) to control water flow into the new siphon because the existing weir would
no longer be in alignment with the canal system.
Once siphon construction and canal modifications are complete, water can then be
diverted into the new siphon and the existing Siphon will be dewatered and completely
sealed (i.e., grouted in place) to prevent exposure to human and ecological receptors.
Fish in the existing Siphon at the time of dewatering will be removed and properly
disposed of. Grout will be injected from both ends of the existing Siphon with a
possibility of injection from above the alignment. The grout will have a permeability of no
more than 1 xio~6 centimeters/second.
The implementation of the Selected Remedy assumes no shutdown of the Irrigation
District's operation (i.e., supplying water for drinking and agricultural irrigation purposes)
is necessary to complete the work. Cofferdams will be installed around the canal
modification areas and a series of pumps will be used to bypass the construction area.
Cost savings may be achieved if temporary shutdown of the Irrigation District's
operation is possible during the construction of the new siphon.
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Post siphon replacement activities will include backfilling, grading, and planting native
vegetation at the temporary access points used to abandon the existing Siphon. The
entire construction phase of this remedy component is estimated to take four months to
complete.
The costs for the purchase of land or to negotiate land easements for the location of the
replacement siphon is not included in the cost estimate from the FS.
Canal Dredging
The area of remediation, under the Selected Remedy, required to meet the sediment
CUL of 0.043 mg/kg Total PCBs spans the width of the Lower West Main Canal Unlined
approximately 4,500 feet beyond the Siphon's exit (i.e., an area approximately 55 feet
wide by 4,500 feet in length) as shown in Figure 25 (Sediment Remediation Area Based
on a Sediment Cleanup Goal of 0.043 mg/kg). Approximately 20 inches of sediment will
be mechanically dredged/excavated from the canal using clamshell excavation methods
or similar equipment. A volume of approximately 20,000 cubic yards of sediment will be
excavated from the canal, which accounts for approximately 6 inches of operator error
during the removal.
During the dredging/excavation of canal sediment, a temporary bridge will be installed
adjacent to the existing bridge downstream of the Siphon's exit to allow the agricultural
equipment and vehicles to cross the canal during the remedial action. During the
remediation of the area, the bridge may be left in place without complicating the
remedy. To prevent migration of contamination into the water column and downstream
during dredging activities, silt curtains will be installed to capture the disturbed
sediment. Excavation of the sediment during low water conditions may not require the
use of silt curtains. Contaminated material will be partially dewatered on the Site using a
series of watertight rolloffs and fractionation tanks, and the sediment will be stabilized
and transported to an approved off-site disposal facility. The sediment will be sampled
prior to disposal to ensure compliance with waste disposal requirements. Prior to the
restoration of the remediation area, confirmation samples will be collected as necessary
to ensure that the remediation satisfies the RAOs for the Site. During remedial action
construction, the levees will be stabilized using imported material to protect against
construction activity and erosion that may occur.
The estimated construction time for this remedy component is five months, and at no
time during these activities will the canal system require shutdown.
Fish Removals
Fish removals will be performed on an annual basis for five years to reduce the
exposure pathway to human receptors by removing fish from the reservoir and canal
system possibly contaminated with PCBs and which are available for human
consumption. The EPA will consider additional fish removal efforts after the five-year
period to determine if additional fish removals should be performed based on whether
the RG for Total PCBs in fish tissue is being met. These fish removals will aid in
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meeting the RAOs for fish tissue and will enhance the effectiveness of the Selected
Remedy by achieving the RGs for fish tissue concentration levels, especially in the
larger fish which bioaccumulate greater concentrations of PCBs through the food chain.
All areas of the Site will be considered when determining where to conduct fish
removals. Fish removals will be accomplished using electrofishing/electroshocking
methods. During periods where low water conditions exist at the Site, fish accumulate in
certain areas and could be removed using seine netting or other applicable methods.
Coordination with the Irrigation District will be required to anticipate low water conditions
and plan the fish removals. The fish will be collected in drums and disposed of at an off-
site disposal facility. Other fish removal methods (e.g., hoop, fyke, and pound nets, etc.)
could be used to supplement the removal efforts.
Fish Tissue Monitoring
Monitoring offish tissue concentrations will be performed to evaluate potential risks to
human health and attainment of the RG for fish tissue. Although the types, number, and
locations offish to be collected during performance monitoring will be determined during
the remedial design of the Selected Remedy, bottom feeders and predatory fish could
be collected from each of the following five established fish collection areas:
• Main Canal - Near the Rio Grande Pump Station.
• Main Canal - Near the weir and the Siphon's entrance.
• Lower West Main Canal Unlined - Near the Siphon's exit.
• Lower West Main Canal Unlined - Near the bridge at FM 1493.
• West Reservoir.
Actual sampling will be determined during the remedial design phase of the Selected
Remedy; however, targeted fish could be a minimum of 8 inches in length and
processed into fillets in the field or by the laboratory for the analysis of Total PCBs.
Collection efforts could focus on the primary targeted species identified in the following
table; however, secondary targeted species could be collected if primary targeted
species are not available.
Predator Species Bottom Feeder Species
• Primary • Primary
Sediment Sampling
Sediment sampling of the canal system will be performed to evaluate the performance
of the remedy. The frequency of the sampling will be determined during the remedial
Largemouth Bass
Smallmouth Buffalo
• Secondary
• Secondary
Smallmouth Bass
Alligator Gar
Common Carp
Channel Catfish
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design of the remedy. Sediment samples collected from the canal system will be
analyzed for Total PCBs.
Performance Monitoring
The Selected Remedy includes performance monitoring to evaluate whether the RAOs
for the Site are being met. Performance monitoring will also be conducted to ensure that
the remedy remains protective of human health and the environment. After the
completion of the remedy, protectiveness of the Selected Remedy will be evaluated
during the Five-Year Reviews required by CERCLA for the Site.
Performance monitoring will occur for a period of time beginning with the collection of
baseline data. Monitoring will include performance standards related to remedy
implementation and will be developed during the remedial design of the remedy
described in the ROD. These performance standards which will be incorporated into
design documents will promote accountability and ensure that the remedy meets the
RAOs stated in the ROD.
Institutional Controls
The Selected Remedy will continue and/or enhance the ICs for the Site. ICs are non-
engineering instruments, such as administrative and/or legal controls, that help
minimize the potential for exposure to contaminants and/or protect the integrity of a
response action by limiting land or resource use. ICs also provide information and
notification to interested persons and communities about any residual contamination left
at a site and any restrictions because of the remaining contamination. ICs typically are
used in conjunction with engineering controls or measures. The engineering controls
considered at this Site, under the Selected Remedy, include: 1) Replacement of the
existing Siphon (i.e., the likely source of the PCBs), and 2) Removal and disposal of the
PCB-contaminated sediment located hydraulically downstream from the existing
Siphon's exit. The NCP emphasizes that ICs are meant to supplement engineering
controls. ICs can include instruments such as signs that are used to minimize access to
contaminated areas or areas that may pose a physical hazard. ICs and engineering
controls can be used to accomplish various remedial objectives and could be
implemented in a series during this remedial action to provide protectiveness of human
health and the environment.
The following ICs will be implemented at the Site for ten years under the Selected
Remedy:
• ICs, in the form of a land-use restriction or notice as to the environmental
conditions of the property, will be required that provides restrictions on or
notification of the modifications to the existing Siphon under Alternative 6 (i.e.,
grouting of the existing Siphon) and which will protect the integrity of the Selected
Remedy. The IC would consist of either a restrictive covenant or a deed notice.
The requirements for filing land use restrictions in the State of Texas are
specified in "30 Texas Administrative Code Chapter 350 Subchapter F." A
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restrictive covenant, or deed notice, is an instrument filed in the real property
records of the county where the affected property is located.
• Signs will be required which warn anglers of the risks associated with the
consumption offish from the Site.
• The existing Aquatic Life Order Number 9, issued by the TDH (predecessor of
the TDSHS), will need to remain in place until fish tissue levels are safe for
human consumption. Knowledge of the order will be enhanced with additional
community outreach to encourage greater awareness of the prohibitions
concerning the taking of all fish species from the Site until the concentrations of
PCBs in fish tissue reach protective concentrations corresponding to the RGs
specified in the ROD.
Public Outreach and Education
The Selected Remedy will include a public outreach and educational program. To be
successful, this program will rely on partnerships with state (i.e., TDSHS, TPWD, and
others), city (i.e., Cities of Donna and Alamo, and other cities), and local entities (i.e.,
Irrigation District, Hidalgo County [Precincts 1 and 2], and other counties), as well as
community-based organizations, to develop activities and measures to reduce the
public's exposure to fish from the Site. Following are outreach and educational activities
and programs that could be considered for implementation at the Site:
• Warnings in English and Spanish printed on water or other utility bills, received
by the public, concerning consumption offish from the Site. These bills are
expected to reach a large portion of the nearby communities such as every
residence and business in Donna and Alamo, Texas.
• Support from community-based organizations such as non-governmental
organizations (NGOs), media, and community relations specialists to inform
people about the risk of consuming contaminated fish.
• Partnering with health fairs, community fairs, and state/local health departments
to provide educational materials and training in multiple languages.
• Distribution of specific outreach materials and messages focused on women of
child-bearing age who consume fish as a part of their diet.
• Conduct outreach, in coordination with the TDSHS, to commercial fish market
owners to inform them about the risks of buying fish from unlicensed vendors.
• Inform anglers about the contaminated fish at the Site and the TDSHS'
enforceable Aquatic Life Order Number 9 which prohibits the taking of all species
of aquatic life from the Site.
• Coordinate enforcement efforts, of the TDSHS' Aquatic Life Order Number 9,
with the TPWD and appropriate law enforcement officials by notifying the
appropriate authorities of individuals accessing the Irrigation District's private
property.
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• Reducing the potential risks posed by consumption of contaminated fish from the
Site by coordinating with the local communities to identify an alternate fishing
location(s) near the Site, routinely stock this nearby lake/reservoir, and advertise
the alternate fishing location.
Five-Year Reviews
Pursuant to CERCLA Section 121(c), 42 U.S.C. § 9621(a), the Selected Remedy will
require statutory Five-Year Reviews since contaminants (i.e., PCBs) will be left on-Site
above levels that permit unrestricted use and unlimited exposure. Although the EPA
routinely evaluates the remedy, a formal review will occur every five years in the form of
a Five-Year Review Report where the EPA will evaluate the performance of the remedy
(i.e., protectiveness of human health and the environment, and effectiveness of the
ICs).
2.10 COMPARATIVE ANALYSIS OF ALTERNATIVES
The NCP, 40 CFR § 300.430(e)(9)(iii), requires the consideration of nine criteria to
evaluate the different remedial alternatives individually and in comparison to each other.
The two threshold criteria which are requirements that each alternative must meet to be
eligible for the selection as a final remedy, are: 1) overall protection of human health
and the environment, and 2) compliance with "applicable or relevant and appropriate
requirements" (ARARs). The five primary balancing criteria which are used to weigh
major trade-offs among alternatives are: 3) long-term effectiveness and permanence;
4) reduction of toxicity, mobility or volume through treatment; 5) short-term
effectiveness; 6) implementability; and 7) cost. The two modifying criteria are: 8) state
acceptance, and 9) community acceptance. The EPA assesses public comments on the
Proposed Plan to gauge community acceptance and has responded to each public
comment received, during the public comment period, in Part 3 (Responsiveness
Summary) of this ROD.
CERCLA Section 121(b), 42 U.S.C. § 9621(b), and 40 CFR 300.430(f)(ii) state that
remedial actions must accomplish the following:
• Be protective of human health and the environment;
• Attain ARARs or provide grounds for invoking a waiver;
• Be cost effective;
• Use permanent solutions and alternative treatment technologies or resource
recovery technologies to the maximum extent practicable; and
• Satisfy the preference for treatment that reduces toxicity, mobility, and volume as
a principal element or explain why it does not meet this criterion.
The following sections of this ROD discuss the relative performance of each alternative
against the NCP's nine criteria and the EPA's rationale for the selection of Alternative 6
(Replace Siphon, Canal Dredging/Excavation, and Fish Removals) as the Selected
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Remedy for the Site. The FS, included in the Administrative Record file for the Site,
contains a detailed analysis of each alternative against the NCP's nine criteria and a
comparative analysis of how the alternatives compare to each other.
2.10.1 Threshold Criteria
Overall Protection of Human Health and the Environment
This criterion addresses whether each alternative provides adequate protection of
human health and the environment and describes how risks posed through each
exposure pathway are eliminated, reduced, or controlled, through treatment,
engineering controls, and/or ICs. This criterion is considered a threshold and must be
met by the selected alternative.
Alternative 1, the NFA Alternative, ranks lowest, in the evaluation criterion for "Overall
Protection of Human Health and the Environment," followed by Alternative 2 (Limited
Action). Alternative 1 takes no measures to protect human health and the environment.
The existing Siphon would continue to act as the primary source of contamination which
poses an unacceptable risk to human health and ecological receptors. The fish would
continue to pose an unacceptable risk to human receptors and ecological receptors
would continue to be exposed to contaminated sediment in the canal system.
The implementation of Alternative 2 would do little to minimize the unacceptable risk to
human health and takes no action in protecting the environment. Engineering controls in
the form of signs and community involvement would only warn the public of the risks of
fish consumption and may not be effective. There is a low overall protection to human
health and no protection to the environment for Alternative 2. Under Alternatives 1 and
2, the existing Siphon would continue to act as the primary likely source of
contamination which poses an unacceptable risk to human health and ecological
receptors. Fish would continue to pose an unacceptable risk to human receptors and
ecological receptors would continue to be exposed to contaminated sediment in the
canal system. No efforts would be made to remove contaminated fish from the reservoir
and canal system under Alternatives 1 and 2.
Alternatives 3 and 6 would provide the highest level of overall protection to human
health and the environment because the sediment contamination above the CUL will be
actively addressed during the remedial action. Sliplining the Siphon, under Alternative 3,
would act as a barrier between the likely source of contamination and migration
pathways into the reservoir and canal system. Replacing the Siphon, under Alternative
6, will eliminate the migration pathway from the likely source by bypassing the source of
contamination and the existing Siphon will be grouted in place.
Leaving the Siphon in place, under both Alternatives 3 and 6, is not anticipated to be a
source of contamination to the Arroyo Colorado River based on analytical data collected
during the Rl. Soil and sediment samples collected from the Arroyo Colorado River and
adjacent to the river indicate that Aroclor-1260 and Total PCB Congener concentrations
upgradient of the Siphon are higher than those downgradient of the Siphon, which
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suggests that the Siphon is not a source of PCBs to the Arroyo Colorado River. Aroclor-
1254 was not detected in any of the soil or sediment samples from the Arroyo Colorado
River. PCBs are hydrophobic and tend to bind to sediment; therefore, the Siphon's
construction materials are not anticipated to migrate into ground water. Ground water
monitor wells were installed during the Rl and samples were collected to evaluate PCBs
in ground water and no unacceptable risk was found.
The canal sediment would be dredged, under Alternatives 3 and 6, to remove sediment
concentrations above 0.043 mg/kg Total PCBs. Figure 4 (Sediment Remediation Area)
depicts the sediment remediation area under Alternatives 3 and 6. Reductions in fish
tissue and mollusk PCB concentrations will occur naturally once the sources of
contamination are contained (i.e., sliplining or replacement of the Siphon under
Alternative 3 and 6, respectively) or removed (i.e., dredging of sediment). Dredging of
the canal sediments will reduce the risk to humans, piscivorous birds and mammals,
aquatic carnivorous mammals, and benthic invertebrates. While reductions in fish tissue
will occur naturally, annual fish removals, under Alternatives 3 and 6, would reduce
unacceptable risk to human receptors faster than if no fish removals were to occur. The
reservoir and canal system is essentially a closed system (i.e., water flows from the Rio
Grande River and unused water flows out at the Donna Drain), and the active physical
removal offish from the reservoir and canal system will significantly aid in meeting the
RAOs for the Site.
Under Alternatives 3 and 6, an analysis of the PCB concentrations in remaining
sediment in the canal system, after removal of the sediment locations that exceed a
CUL of 0.043 mg/kg Total PCBs, results in an overall 95% UCL of 0.00276 mg/kg Total
PCBs in sediment. This concentration is below the calculated sediment CUL based on:
1) a 10~5 adult recreational fisher cancer risk level (i.e., 0.004 mg/kg), and 2) an Aroclor-
1254 child recreational fisher non-cancer HI of 1 (i.e., 0.003 mg/kg). Therefore, removal
of sediment greater than 0.043 mg/kg Total PCBs should result in fish tissue
concentrations that will be protective of recreational fishers below a 10"5 cancer risk
level and an Aroclor-1254 non-cancer HI of 1.
Compliance with Applicable or Relevant and Appropriate Requirements
Section 121(d) of CERCLA, 42 U.S.C. § 9621(d), and 40 CFR § 300.430(f)(1)(ii)(B)
require that remedial actions at CERCLA sites at least attain legally applicable or
relevant and appropriate federal and state requirements, standards, criteria, and
limitations that are collectively referred to as ARARs, unless such ARARs are waived
pursuant to CERCLA Section 121(d)(4), 42 U.S.C. § 9621(d)(4). This criterion is
considered a threshold and must be met by the selected alternative.
Applicable requirements are those cleanup standards, standards of control, and other
substantive requirements, criteria, or limitations promulgated pursuant to federal
environmental or state environmental or facility siting laws that specifically address a
hazardous substance, pollutant, contaminant, remedial action, location, or other
circumstances found at a CERCLA site. Only those state standards that are identified
by a state in a timely manner and that are more stringent than federal requirements may
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be applicable. Relevant and appropriate requirements are those cleanup standards,
standards of control, and other substantive requirements, criteria, or limitations
promulgated pursuant to federal environmental or state environmental or facility siting
laws that while not "applicable" to a hazardous substance, pollutant, contaminant,
remedial action, location, or other circumstances at a CERCLA site address problems or
situations sufficiently similar to those encountered at the CERCLA site that their use is
well-suited to the particular site. Only those state standards that are identified by a state
in a timely manner and that are more stringent than federal requirements may be
relevant and appropriate. Section 2.13.2 (Compliance with Applicable or Relevant and
Appropriate Requirements) and Appendix D (Determination of Applicable or Relevant
and Appropriate Requirements) of this ROD include the ARARs for the Site.
Compliance with ARARs addresses whether a remedy will meet all the applicable or
relevant and appropriate requirements of other federal and state environmental statues
or provides a basis for invoking a waiver.
Alternatives 1 and 2 would not meet the threshold criteria of protection of human health
and the environment and compliance with ARARs.
It is anticipated that Alternatives 3 and 6 would meet the threshold evaluation criterion of
compliance with ARARs, including those related to PCBs and the Toxic Substances
Control Act. Both alternatives are assumed to comply with the location- and action-
specific ARARs because the required engineering design and agency review process
can ensure that the selected remedy complies with the applicable ARARs. Both
alternatives can be designed and implemented in compliance with ARARs pertaining to
the management and disposal of generated materials (i.e., sediment and fish).
Furthermore, the remedial design phase of the remedy can address the various land
use and resource protection ARAR requirements (e.g., habitat preservation and
mitigation).
2.10.2 Balancing Criteria
Long-Term Effectiveness and Permanence
This criterion refers to the expected residual risk and the ability of a remedy to maintain
reliable protection of human health and the environment over time, once cleanup levels
have been met. This criterion is used to weigh major trade-offs among alternatives.
Alternative 1 ranks lowest in the evaluation criterion for "Long-term Effectiveness and
Permanence," followed by Alternative 2. These alternatives do not provide long-term
effectiveness since there is no active remediation of the PCBs at the Site. The likely
source of contamination (i.e., the Siphon) would continue to deposit PCBs in the
downstream sediment until the contaminants in the source material are completely
depleted. The PCBs would continue to bioaccumulate and biomagnify through the food
chain. Under Alternative 2, it is possible that the ICs, engineering controls, and
community involvement activities will not be successful at preventing the consumption
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of fish collected from the reservoir and canal system; therefore, the effectiveness for this
alternative is questionable.
Alternatives 3 and 6 provide long-term effectiveness and permanence because
contaminated sediment would be removed from the Site. Additionally, sliplining the
Siphon, under Alternative 3, or replacing the Siphon, under Alternative 6, mitigate the
transport pathway to human and ecological receptors from the likely PCB source into
the Site, in the long-term, and are permanent source removal remedies. However,
Alternative 6 provides a higher level of long-term effectiveness and permanence than
Alternative 3 because the existing Siphon, during or after sliplining under Alternative 3,
could lose structural stability due to the age of the structure. The Siphon was
constructed in approximately 1926 and is probably approaching the end of its design
life. While sliplining will extend the life of the Siphon, the Siphon must withstand the
dewatering, uncovering, and slipline installation. It is possible that the concrete and
steel may have degraded over time and will not withstand the process. If the Siphon
were to collapse or fail during the sliplining process or after remediation, another
alternative may have to be implemented. Under Alternative 6 a new structure would be
required.
Removal of the PCB-contaminated sediment downstream of the Siphon's exit will
reduce sediment PCB concentrations to below the CUL under both alternatives.
Additionally, annual fish removals would eliminate residual contamination from the
system. Removal of contaminated sediment and mitigating the likely source of the PCBs
into the Site will also be protective of ecological receptors under both alternatives.
Reduction of Toxicity, Mobility, or Volume through Treatment
This criterion refers to the anticipated performance of the treatment technologies that
may be included as part of a remedy. This criterion is used to weigh major trade-offs
among alternatives.
The NCP, at 40 C.F.R § 300.430(a)(1)(iii)(A), establishes a preference for the use of
treatment to address the principal threats posed by a site wherever practicable. The
"principal threat" concept is applied to the characterization of "source materials" at a
Superfund site. A source material is material that includes or contains hazardous
substances, pollutants or contaminants that act as a reservoir for migration of
contamination to ground water, surface water, or air; or acts as a source for direct
exposure. Principal threat wastes are those materials considered to be highly toxic or
highly mobile that generally cannot be reliably contained or would present a significant
risk to human health or the environment should exposure occur. Low-level threat wastes
are those materials that generally can be reliably contained and that would present only
a low risk in the event of exposure.
The source material at the Site is found in the existing Siphon and the contaminated
sediment located downstream of the Siphon's exit. The source material is not highly
toxic or highly mobile and thus is low-level waste and not principal threat waste.
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The HHRA (EA 2016b) determined that there were no unacceptable human health
concerns for direct contact with sediment containing PCBs. The carcinogenic risks for
the adult, adolescent, and child recreational users are 1x10~7, respectively, which are all
below the lower end of the EPA's target risk range (i.e., 1 x10~6). The total non-
carcinogenic His for the adult, adolescent, and child recreational users are 0.008, 0.03,
and 0.05, respectively, which are all below the EPA's acceptable threshold (i.e., 1.0).
Also, PCBs are hydrophobic, which means that they tend to bind to sediment particles,
organic matter in sediment, and fatty tissues in biota (EA 2016b). Suspended sediment
in water at the Site tends to settle out onto the bottom of the canal system immediately
downgradient of the existing Siphon's exit due to low water velocities with distance from
the exit. The Rl (EA 2016a) determined that the highest concentrations of PCBs were
found immediately downgradient of the existing Siphon's exit. As a result, contaminated
sediment is effectively contained within the reservoir and canal system and is not
considered a highly mobile source material.
Additionally, it is likely that the Siphon's construction/repair materials (e.g., concrete,
caulking, grout, or sealants) were a primary source of contamination at the Site. The Rl
(EA 2016a) determined that the concentrations of PCBs in the surface water taken from
within the existing Siphon and analyzed for Total PCB Congeners ranged from 190 to
1,700 picograms/liter (pg/L). These concentrations are well below the federal surface
water quality criteria for aquatic life (i.e., 14,000 pg/L) and the Total PCB maximum
contaminant level for drinking water (i.e., 500,000 pg/L).
Alternatives 1 and 2 do not provide any reduction in toxicity, mobility, or volume through
treatment, and are therefore ranked the lowest of all alternatives. Although none of the
alternatives include treatment technologies, Alternatives 3 and 6 will further reduce the
mobility of contaminants at the Site because once the contaminated sediment is
excavated and the Siphon sliplined or replaced, PCBs will not be able to leach into the
surface water. Alternatives 3 and 6 will also reduce the volume of contaminated
sediment by dredging/excavating the contaminated sediment downgradient of the
Siphon's exit.
Short-Term Effectiveness
This criterion addresses the period of time needed to implement the remedy and any
adverse impacts that may be posed to workers, the community, and the environment
during construction and operation of the remedy until cleanup levels are achieved. This
criterion is used to weigh major trade-offs among alternatives.
No activity is performed under Alternative 1, the NFA Alternative; therefore, it poses no
additional short-term impacts to the community. Alternative 2 provides minimal or low
short-term impacts to the community in terms of the carbon footprint associated with ICs
and community involvement activities implemented at the Site (i.e., activities associated
with the installation of signs and travel for the community involvement representatives).
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The community could be affected by an increase in traffic caused by the transportation
of equipment and materials under Alternatives 3 and 6. The local agricultural industry
may be affected by limited road access near remedial action construction areas. A
temporary bridge to facilitate agricultural traffic over the canal during remedial activities
will be constructed; however, access to fields located directly adjacent to the canal
segments at the Siphon's entrance and exit may be impeded. Additionally, dust may be
produced during construction and transportation activities, but can be mitigated through
standard construction practices. Environmental impacts associated with construction
around the new or existing Siphon include the effects of diverting and dewatering the
Arroyo Colorado River and the Siphon. Environmental impacts associated with the
dredging/excavation of sediment from the canal and fish removals include reducing the
population of benthic organisms and fish. Although silt curtains would be used, if
needed, dredging/excavating the canal would also disturb sediment which could
increase exposure to downstream ecological receptors. Additionally, air emissions from
heavy equipment and vehicles would possibly negatively impact the environment.
A factor to consider when evaluating short-term effectiveness is the length of time it
would take to perform the construction activities. The construction time has a direct
correlation to risks associated with construction and transportation activities as well as
the carbon footprint. Alternative 6 is ranked the lowest because it requires an estimated
nine months to construct, while Alternative 3 requires an estimated seven months.
Implementability
This criterion considers the technical and administrative feasibility of a remedy from
design through construction and operation. Factors such as the relative availability of
services and materials, administrative feasibility, and coordination with other
governmental entities are also considered. This criterion is used to weigh major trade-
offs among alternatives.
The implementability evaluation criterion ranks the highest when complication from
construction is the lowest. Implementability is not applicable to Alternative 1 since no
action would be taken. Alternative 2 has the highest implementability, compared to
Alternatives 3 and 6, due to the absence of a construction component; however, this
alternative is not protective of human health and the environment (i.e., a threshold
criteria).
Alternative 3 includes complexities associated with the structural integrity and the age of
the Siphon. The Siphon was constructed in approximately 1926 and is probably
approaching the end of its design life. While sliplining will extend the life of the Siphon,
the Siphon must withstand the remedial action components of dewatering, uncovering,
and slipline installation. It is possible that the concrete and steel used to construct the
Siphon may have degraded over time and will not withstand the sliplining or remediation
process. If the Siphon were to collapse or fail during the sliplining process or after
remediation, another alternative may have to be implemented. Under Alternative 6, a
new siphon would be required. Considering the complexities associated with the
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structural integrity and the age of the Siphon, Alternative 6 would rank higher than
Alternative 3 under this implementability criteria.
Additionally, Alternative 3 includes other complexities associated with the installation of
the slipline such as obtaining the proper alignment within the existing Siphon and
completely filling the void space with grout. Under Alternative 6, a new siphon would be
required. Considering the complexities associated with the installation of the slipline,
Alternative 6 would rank higher than Alternative 3 under this implementability criteria.
Considering the construction complexities associated the potential acquisition of land
and the potential negotiation of land easements, Alternative 3 ranks higher than
Alternative 6 because implementation of the slipline remedy would not require the
potential acquisition of land or the negotiation of easements.
The feasibility of implementing Alternatives 3 and 6 is dependent on which season
construction takes place. Under Alternative 3, during periods of high water demand,
sliplining may be more difficult to implement because water would be pumped at a
higher flowrate to bypass the existing Siphon. Under Alternative 6, during periods of
high water demand, construction may be more difficult when installing the new weir and
transitioning water flow into the new siphon. Under both alternatives, a higher flowrate in
the canal would also result in an increase in the level of suspended sediment when the
material is disturbed during dredging.
Under Alternatives 3 and 6, implementing the fish removals is feasible because this field
activity in these areas have been previously performed, and equipment and specialists
are available for these activities.
The administrative feasibility to construct the remedy, implement the monitoring
requirements, access the equipment and specialists, and coordinate with the
appropriate regulatory agencies are the same for Alternatives 3 and 6. Both alternatives
would require coordination with numerous governmental entities who may have control
or ownership over the construction area, especially during the implementation of
sliplining the existing Siphon or the installation of a new siphon. Specifically, these
activities would have to be coordinated with the IBWC or other entities that may have
jurisdiction of the levees or the area located at the entrance and near the exit of the
existing Siphon, including the location for the new siphon.
Costs
This criterion includes estimated capital and operation and maintenance costs as well
as present worth costs. Present worth cost is the total cost of an alternative over time in
terms of today's dollar value. Cost estimates are expected to be accurate within a range
of +50 to -30 percent. The selection of a remedial alternative is not solely based on cost;
however, cost may be used to select between alternatives that perform favorably when
comparing the other criteria. This criterion is used to weigh major trade-offs among
alternatives.
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The estimated present worth costs for the Selected Remedy are included in Appendix C
(Costs, Replace Siphon and Dredging of Canal Sediment with Off-Site Disposal), which
provides the detailed cost estimate for the implementation of the remedial action. These
costs are divided into Siphon replacement and sediment dredging costs. The costs for
land purchase or to negotiate land easements have not been included in Alternative 6,
but may be necessary.
The estimated present worth costs for the alternatives considered in the FS range from
$0 for Alternative 1 to $19.4 million for Alternative 6. The costs for each alternative are
presented in the following table:
Summary of Remedial Alternative Costs
Alternative 1
No Further Action
Alternative 2
Limited Action
Alternative 3
Slipline Siphon, Canal
Dredging, and Fish
Removals
Alternative 6
Replace Siphon, Canal
Dredging, and Fish
Removals
Cost
$0
$1.6 Million
$15.6 Million
$19.4 Million
2.10.3 Modifying Criteria
State/Support Agency Acceptance
This criterion considers whether the State agrees with the EPA's analyses and
recommendations of the Ri/FS and the Proposed Plan. In the final balancing of trade-
offs between alternatives upon which the final remedy selection is based, modifying
criteria are of equal importance to the balancing criteria.
The State of Texas, represented by the TCEQ, was provided the opportunity to review
and comment on the Selected Remedy and agrees with the EPA's Selected Remedy
(Alternative 6 - Replace Siphon, Dredge Sediments, and Fish Removals).
Community Acceptance
This criterion considers whether the local community agrees with the EPA's analyses
and the Preferred Alternative of the Proposed Plan. Any comments received on the
Proposed Plan are an important indicator of community acceptance. In the final
balancing of trade-offs between alternatives upon which the final remedy selection is
based, modifying criteria are of equal importance to the balancing criteria.
The EPA conducted two public meetings on May 22, 2018, in Alamo and Donna, Texas,
to present the Proposed Plan and the EPA's Preferred Alternative 6 (Replace Siphon,
Canal Dredging, and Fish Removals) to the public and to solicit the public's comments.
Based upon the oral and written comments received during the public meetings and
during the public comment period for the Proposed Plan, the community did not oppose
the EPA's Selected Remedy (i.e., Alternative 6) described in this ROD.
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The EPA periodically met with local, county, and state/federal public officials (i.e.,
Mayors and City Managers for the Cities of Donna and Alamo, Hidalgo County
representatives, Texas Secretary of State representatives, TCEQ, USFWS, IBWC, and
other public officials), including several community-based organizations (i.e., non-
governmental organizations or others) and representatives from the Irrigation District
during the implementation of the Rl and fish removal actions. These meetings helped
the EPA to become better aware of the issues and concerns held by the local officials
and the public and in preparing this ROD.
The EPA assesses the public's comments on the Proposed Plan to gauge community
acceptance of the EPA's Preferred Alternative 6 and has responded to each public
comment received in Part 3 (Responsiveness Summary) of this ROD.
2.11 PRINCIPAL THREAT WASTES
The NCP, at 40 C.F.R § 300.430(a)(1)(iii)(A), establishes a preference for the use of
treatment to address the principal threats posed by a site wherever practicable. The
"principal threat" concept is applied to the characterization of "source materials" at a
Superfund site. A source material is material that includes or contains hazardous
substances, pollutants or contaminants that act as a reservoir for migration of
contamination to ground water, surface water, or air; or acts as a source for direct
exposure. Principal threat wastes are those materials considered to be highly toxic or
highly mobile that generally cannot be reliably contained or would present a significant
risk to human health or the environment should exposure occur. Low-level threat wastes
are those materials that generally can be reliably contained and that would present only
a low risk in the event of exposure.
The source material at the Site is found in the existing Siphon and the contaminated
sediment located downstream of the Siphon's exit. The Siphon and the contaminated
sediment are not highly toxic or highly mobile, and thus are low-level waste and not
principal threat waste.
The HHRA (EA 2016b) determined that there were no unacceptable human health
concerns for direct contact with sediment containing PCBs. The carcinogenic risks for
the adult, adolescent, and child recreational users are 1x10~7, respectively, which are all
below the lower end of the EPA's target risk range (i.e., 1 x10~6). The total non-
carcinogenic His for the adult, adolescent, and child recreational users are 0.008, 0.03,
and 0.05, respectively, which are all below the EPA's acceptable threshold (i.e., 1.0).
Also, PCBs are hydrophobic, which means that they tend to bind to sediment particles,
organic matter in sediment, and fatty tissues in biota (EA 2016b). Suspended sediment
in water at the Site tends to settle out onto the bottom of the canal system immediately
downgradient of the existing Siphon's exit due to low water velocities with distance from
the exit. The Rl (EA 2016a) determined that the highest concentrations of PCBs were
found immediately downgradient of the existing Siphon's exit. As a result, contaminated
sediment is effectively contained within the reservoir and canal system and is not
considered a highly mobile source material.
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Additionally, it is likely that the Siphon's construction/repair materials (e.g., concrete,
caulking, grout, or sealants) were a primary source of contamination at the Site. The Rl
(EA 2016a) determined that the concentrations of PCBs in the surface water taken from
within the existing Siphon and analyzed for Total PCB Congeners ranged from 190 to
1,700 picograms/liter (pg/L). These concentrations are well below the federal surface
water quality criteria for aquatic life (i.e., 14,000 pg/L) and the Total PCB maximum
contaminant level for drinking water (i.e., 500,000 pg/L).
2.12 SELECTED REMEDY
Based on the consideration of the requirements of CERCLA, the detailed analysis of
remedial alternatives, consultations with the TCEQ, and the consideration of the public's
comments, the EPA has selected Alternative 6 (Replace Siphon, Dredge Canals, and
Fish Removals) as the Selected Remedy for the Site. This section of the ROD provides
the EPA's rationale for the selection of the Selected Remedy, including a description of
its anticipated scope, how the remedy will be implemented, and its expected outcomes.
2.12.1 Summary of the Rationale for the Selected Remedy
The Selected Remedy is protective of human health and the environment, complies with
ARARs, and provides the best balance of tradeoffs among the balancing criteria. It
reduces risks within a reasonable time frame, provides for long-term reliability of the
remedy, and minimizes reliance on ICs. It will achieve substantial risk reduction by
mitigating the transport pathway between the existing Siphon and the reservoir and
canal system and by removing the most contaminated sediment downstream of the
Siphon's exit. Removal of the contaminated sediment to concentrations below the CUL
will reduce the fish tissue concentrations to below the RG which is protective of human
receptors and will also be protective of ecological receptors. Human health risks will
significantly be reduced through the fish removals, ICs, and the implementation of a
community involvement program.
2.12.2 Description of the Selected Remedy
The Selected Remedy is considered a final remedial action for the Site and addresses
the following source of contaminants, receptors, and Site media:
• The likely source of PCB contamination at the Site (i.e., the Siphon),
• Site-related human health risks associated with consumption offish, and
• Site-related ecological risks from contaminated sediment.
The Selected Remedy includes the following major components:
• Removal of approximately 20,000 cubic yards of sediment exceeding the CUL of
0.043 mg/kg Total PCBs, located in the canal approximately 4,500 feet
downstream of the Siphon's exit, and transportation to an off-site disposal facility;
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• Replacement (i.e., construction of a new siphon) and abandonment of the
existing Siphon (i.e., grouting in place);
• Removal of fish annually for five years from all sections of the Site (additional fish
removals will be considered based on the attainment of the fish tissue RG);
• Post remediation Site monitoring that includes:
— Frequency offish tissue monitoring and sediment sampling of the canal
system will be determined during the remedial design of the Selected
Remedy;
• Implementation of a public outreach program for ten years to inform the
community of the potential health risks associated with consuming fish from the
Site;
• Installation and maintenance of signs at the Site for ten years to warn people of
the risks associated with consuming fish from the Site;
• Coordination with the TDSHS to maintain the Aquatic Life Order Number 9 until
the fish tissue concentrations have reached the fish tissue Remediation Goal of
0.031 mg/kg Total PCBs;
• Implementation of an IC(s), in the form of a land-use restriction or notice as to the
environmental conditions of the property, which will protect the integrity of the
Selected Remedy, and evaluation of the appropriate IC(s) in consultation with the
TCEQ; and
• Performance of statutory Five-Year Reviews to evaluate the performance of the
Selected Remedy.
2.12,3 Summary of the Estimated Costs for the Selected Remedy
The estimated present worth costs for the Selected Remedy are included in Appendix C
(Costs, Replace Siphon and Dredging of Canal Sediment with Off-Site Disposal), which
provides the detailed cost estimate for the implementation of the remedial action. These
costs are divided into Siphon replacement and sediment dredging costs.
The information in the following cost estimate summary table for the Selected Remedy
is based on the best available information regarding the anticipated scope of Alternative
6. Changes in the cost elements are likely to occur because of new information and
data collected during the engineering remedial design of the Selected Remedy. Major
changes may be documented in the form of a memorandum in the Administrative
Record file, an Explanation of Significant Differences, or a ROD Amendment. This cost
estimate for the Selected Remedy is an order-of-magnitude engineering cost estimate
that is expected to be within plus 50 to minus 30 percent of the actual project cost.
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Cost Estimate for Alternative 6
Ahcrn:ili\c (>: Kcphicc Siphon. C':in:il l)ivd<>in<>. anil I'isli Rcmoxnls
Component
Cost w
Details
Timeframe
Replace Siphon
$8,100,000 (2)
Install new siphon adjacent to existing
Siphon. Fill existing Siphon with grout and
leave in place.
4 months
Dredging of Canal
Sediment with Off-Site
Disposal
$7,600,000 (2)
Excavate canal sediment above
0.043 mg/kg Total PCBs and transport to
an off-site disposal facility.
5 months
Fish Removal
$3,000,000 (3)
Remove fish from the canal and reservoir
system using electrofishing and other fish
removal methods.
Annually for 5 years.
Post Remediation
Site Monitoring
$410,000 ®
Sample fish tissue for Total PCBs.
Determined during the
remedial design of the
Selected Remedy.
$150,000 ®
Sample sediment in the canal system for
Total PCBs.
Determined during the
remedial design of the
Selected Remedy.
Community
Involvement and
Engineering Controls
$140,000 (3)
Implement a public outreach program that
will inform the community on the potential
health risks associated with consuming fish
from the site. Signs will be used to warn
people at the site of risks.
10 years
Institutional Controls
$0
Aquatic Life Order Number 9, maintained
by TDSHS.
Until the fish tissue
remediation goal has
been reached.
$0
Land-use restriction to prevent disturbance
of the existing siphon.
As long as the existing
Siphon remains.
Total Cost $19,400,000 (3)
Note:
(1) Costs and total are rounded ARAR - Applicable or Relevant and Appropriate Requirement
(2) Capital Cost PCBs - Polychlorinated Biphenyls
(3) Net Present Value (7 percent discount), TDSHS - Texas Department of State Health Services
this cost estimate does not include the costs
to purchase land or negotiate land easements.
2,12.4 Expected Outcomes of the Selected Remedy
The intent of the Selected Remedy is to be protective of human health and the
environment and to attain ARARs. It is consistent with current and reasonably
anticipated future uses of the land and resources (i.e., soil, surface water, and ground
water). It is also intended to minimize the reliance on ICs to the extent practicable. The
Selected Remedy will eliminate the contaminant transport pathway from the likely
source (i.e., the Siphon), address the highest sediment contamination at the Site,
manage short-term risks, and with time reduce fish tissue concentrations at the Site to
achieve long-term protectiveness to human and ecological receptors.
2.13 STATUTORY DETERMINATIONS
Pursuant to CERCLA Section 121, 42 U.S. Code §9621, and 40 CFR 300.430(f) the
EPA must select remedies that are protective of human health and the environment,
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comply with ARARs (unless a statutory waiver is justified), are cost-effective, and utilize
permanent solutions and alternative treatment technologies or resource recovery
technologies to the maximum extent practicable. In addition, CERCLA includes a
preference for remedies that employ treatment that permanently and significantly
reduce the volume, toxicity, or mobility of hazardous wastes as their principal element.
The following sections of this ROD discuss how the Selected Remedy meets these
statutory requirements.
2.13.1 Protection of Human Health and the Environment
The Selected Remedy will protect human health and the environment by eliminating the
contaminant transport pathway from the likely source (i.e., the Siphon) into the
environment. The Selected Remedy will remove the sediment with the highest
concentrations of PCBs, will manage short-term human health risks while fish tissue
concentrations decrease with ICs and engineering controls, and will implement a
community involvement program. Specifically, the exposure of recreational fishers to
PCBs in fish tissue will be reduced through the removal of contaminated sediment
above the CUL and the removal of the fish from the reservoir and canal system.
Ecological receptors of concern will be protected because they will no longer be
exposed to PCBs in sediment at levels that result in unacceptable risk.
2.13.2 Compliance with Applicable or Relevant and Appropriate Requirements
and To-Be-Considered Criteria
The NCP §§ 300.430(f)(5)(ii)(B) and (C) require that a ROD describe the federal and
state ARARs that the Selected Remedy will attain or provide justification for any
waivers. The implementation of the Selected Remedy generally will not require federal,
state, or local permits for on-site response actions (40 CFR 300.400[e][1]), but remedial
actions must be completed in conformance with the substantive technical requirements
of applicable permit regulations.
ARARs can be classified into the following three categories, although some ARARs may
belong to more than one of these categories:
• Chemical-specific ARARs: Typically the environmental laws or standards that
result in the establishment of health- or risk-based numerical values. Chemical-
specific ARARs are generally identified with reference to specific media and
COCs. For example, identifying surface water as a medium of concern triggers
consideration of federal clean water regulations;
• Location-specific ARARs: Include restrictions placed on concentrations of
hazardous substances or the implementation of certain types of activities based
on the location of a site. Some examples of specific locations include floodplains,
wetlands, historic places, land use zones, and sensitive habitats; and
• Action-specific ARARs: Generally technology or activity-based limitations or
guidelines for management of pollutants, contaminants, or hazardous wastes.
These ARARs are triggered by the type of remedial activity selected to achieve
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the RAOs and these requirements may indicate how the potential alternative
must be achieved.
To-Be-Considered (TBC) criteria are non-promulgated, non-enforceable guidelines, or
criteria that may be useful for developing a remedial action or that are necessary for
evaluating what is protective for human health and/or the environment. Examples of
TBC criteria include EPA drinking water health advisories, reference doses, and cancer
slope factors.
The ARARs for the Site are described in the following sections of this ROD. There are
no chemical-specific ARARs or TBC criteria applicable to the Site.
Location-Specific ARARs
National Historical Preservation Act
The National Historical Preservation Act (16 U.S. Code Section 470 et seq., 36 CFR
Parts 63, 65, and 800) may be applicable if scientific, historical, and archeological data
are discovered during the project.
National Flood Insurance Program
The National Flood Insurance Program (42 U.S.C. § 4101 et. seq; 44 C.F.R Part 60)
prohibits alteration to rivers or floodplains that may increase potential for flooding. This
regulation may be applicable because the Site lies within a 100-year floodplain.
Executive Order 11988, Floodplains Management
Executive Order 11988, Floodplains Management (40 CFR Part 6 Appendix A; 40 CFR
Section 6.302; and 42 Federal Register 26951 [May 24, 1977]), requires federal
agencies to evaluate the potential effects of actions taken in a floodplain to avoid
adverse impacts. The requirements of this Act are applicable because the Site lies
within a 100-year floodplain.
Endangered Species Act of 1973
The Endangered Species Act of 1973 (16 U.S. Code Sections 1531, 1532, 1533, 1535,
and 1536; and 50 CFR Part 17) requires that federal agencies must confirm any action
that is federally authorized, funded, or implemented by the agency is not probable to
adversely affect the continued existence of any threatened and endangered species.
This Act is applicable if threatened and endangered species are found at the Site.
Migratory Bird Treaty Act
The Migratory Bird Act (16 U.S. Code §§ 703-712) establishes federal responsibility for
the protection of the international migratory bird resource and requires continued
consultation with the U.S. Fish and Wildlife Service during remedial design and remedial
action activities to ensure that the cleanup of the Site does not unnecessarily impact
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migratory birds. The requirements of this Act are applicable if the remedy may impact
migratory birds.
Texas Administrative Code and Texas Parks and Wildlife Department
The Texas Administrative Code, Title 31 Natural Resources and Conservation; and Part
2 Texas Parks and Wildlife Department, Chapter 65 Wildlife; requires that no person
may take, possess, propagate, transport, sell or offer for sale, or ship any species offish
or wildlife listed as threatened or endangered. There is uncertainty regarding whether
threatened and endangered species are located at the Site. The ERA conservatively
assumed that any threatened or endangered species that could occur within Hidalgo
County may be present at the Site. These requirements are applicable if threatened or
endangered species are found at the Site.
Action-Specific ARARs
Resource Conservation and Recovery Act
The Resource Conservation and Recovery Act (RCRA, 40 CFR Parts 260 to 268),
Subchapter III (Hazardous Waste Management, 42 U.S.C. §§ 6921 et. seq.; 40 C.F.R.
Part 262), regulates general hazardous waste management including identification,
generation, transportation, storage, disposal of waste; permitting, monitoring, and
reporting requirements; authorizations and recognition of state hazardous waste
programs; and chemical release reporting. The requirements of this Act are applicable if
hazardous waste as defined by RCRA (listed or characteristic) is identified at the Site
and requires disposal.
Toxic Substances Control Act
The Toxic Substances Control Act (TSCA; 15 U.S.C. § 2601 et. seq.; 40 CFR part 761)
regulates PCBs from their manufacture to disposal.
The requirements of this Act are applicable if PCB remediation waste is generated
during remedial activities.
Hazardous Materials Transportation Act
The Hazardous Material Transportation Act (49 U.S.C. §§ 5101 et. seq.; 49 CFR Parts
171-180) requires standards for packaging, documenting, and transporting hazardous
materials.
This Act is applicable if hazardous materials are transported off-Site for treatment or
disposal.
Texas Administrative Code
Texas Administrative Code Title 30 Environmental Quality, Part 1 Texas Commission on
Environmental Quality, Chapter 335 Industrial Solid Waste and Municipal Hazardous
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Waste requires standards for industrial solid waste and municipal hazardous waste
depending on classification as hazardous, Class 1, Class 2, or Class 3 waste. 30 Texas
Administrative Code, at § 335.508(5), states that media contaminated by a material
containing greater than or equal to 50 ppm total PCBs and wastes containing greater
than or equal to 50 ppm PCBs shall be classified as Class 1 waste. This regulation is
applicable if hazardous, Class 1, Class 2, or Class 3 wastes are generated during
remedial activities.
Texas Administrative Code Title 30 Environmental Quality, Part 1 Texas Commission on
Environmental Quality, Chapter 327 Spill Prevention and Control defines reportable
quantities, notification requirements, and actions required in the event of a spill or
release to the environment of oil, petroleum product, used oil, hazardous substances,
industrial solid waste or other substances. This regulation is applicable if a release or
spill to the environment occurs during remedial activities.
Texas Administrative Code Title 30 Environmental Quality, Part 1 Texas Commission on
Environmental Quality, Chapter 279 Water Quality Certification establishes procedures
and criteria for applying for, processing, and reviewing state certifications under the
Clean Water Act Section 401. This regulation is applicable if remedial activities occur in
the Arroyo Colorado River.
Texas Administrative Code Title 30 Environmental Quality, Part 1 Texas Commission on
Environmental Quality, Chapter 307 Texas Surface Water Quality Standards sets forth
criteria for surface water in Texas. This regulation is applicable if remedial activities
occur in the Arroyo Colorado River.
Clean Water Act
The Clean Water Act (CWA), Section 401 Certification (33 U.S.C. § 1341), requires
applicants for National Pollutant Discharge Elimination System (NPDES) permits to
obtain certification from state or regional regulatory agencies that the proposed
discharge will comply with the Clean Water Act Sections 301, 302, 303, 306 and 307.
On-site discharges would not require a NPDES permit, but would require compliance
with substantive requirements. For off-site actions, certification should occur as part of
the state identification of substantive state ARARs (USEPA 1998). This Act would be
applicable if remedial activities occur in the Arroyo Colorado River.
The CWA, Section 402 (33 U.S.C. § 1342; 40 C.F.R. Part 125), requires that both on-
site and off-site discharges of pollutants from Superfund sites to navigable waters of the
United States meet the substantive requirements of the CWA. On-site discharges must
comply with the substantive technical requirements of the CWA but do not require a
permit. Off-site discharges would be regulated under the conditions of a National
Pollutant Discharge Elimination System (NPDES) permit. In Texas, the NPDES program
is administered by TCEQ (see Texas Water Code, Title 2 Water Administration, Chapter
26 Water Quality Control). This Act would be applicable if remedial activities occur in the
Arroyo Colorado River.
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The CWA, Section 404 (33 U.S.C. § 1344), applies to dredging, in-water disposal,
capping, construction of berms or levees, stream channelization, excavation, and/or
dewatering in navigable waters of the United States. This Act is applicable if remedial
activities occur in the Arroyo Colorado River.
The CWA, Sections 303 and 304, Federal Water Quality Criteria (33 U.S.C. § 1313-14),
requires that individual states have established water quality standards to protect
existing and attainable uses of surface water. These water quality standards may be
applicable if remedial activities occur in the Arroyo Colorado River.
Texas Water Code
The Texas Water Code, Title 2 Water Administration, Chapter 26 Water Quality Control
(Texas Water Code § 26.121), prohibits any discharge of pollutants into or adjacent to
waters in the state except as authorized by the TCEQ. The TCEQ is delegated the
authority to issue permits for the discharge of pollutants to the same extent as the
NPDES permit program administered by the EPA under the CWA Section 402. On-site
discharges must comply with the substantive requirements of the CWA but do not
require a permit. Off-site discharges would be regulated under the conditions of a Texas
Pollutant Discharge Elimination System (TPDES) permit. Direct discharges must meet
technology-based requirements. This Act is applicable if remedial activities occur in the
Arroyo Colorado River.
Rivers and Harbors Act
The Rivers and Harbors Act of 1899, Obstruction of Navigable Waters (33 U.S.C. §
401), controls the alteration of navigable waters, including construction of structures
such as piers, berms and installation of pilings, as well as excavation and fill. No permit
is required for on-site activities, but in-water construction activities must comply with the
substantive requirements of the Act. This Act is applicable if remedial activities occur in
the Arroyo Colorado River.
Fish and Wildlife Coordination Act
The Fish and Wildlife Coordination Act (16 U.S. Code Section 662 et. seq.) is applicable
when modifications to a stream or other water body are proposed or approved by any
United States agency, and such agency shall review with the U.S. Fish and Wildlife
Service, Department of the Interior, and with the head of the agency overseeing the
wildlife resources of the Site. The requirements of this Act are applicable if remedial
activities would modify streams or other water bodies.
2.13.3 Cost Effectiveness
The Selected Remedy is cost-effective and represents a reasonable value for the costs
incurred. Section 300.430(f)(1)(ii)(D) of the NCP states that "A remedy shall be cost
effective if its costs are proportional to its overall effectiveness." The EPA evaluated the
"overall effectiveness" of those alternatives that satisfied the threshold criteria (i.e.,
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protection of human health and the environment and compliance with ARARs) by
assessing three of the five balancing criteria in combination (long-term effectiveness
and permanence; reduction in toxicity, mobility, and volume through treatment; and
short-term effectiveness). Overall effectiveness was then compared to costs to
determine cost-effectiveness. The overall effectiveness of this remedial alternative was
determined to be proportional to its costs and therefore the Selected Remedy (i.e.,
Alternative 6) represents a reasonable value for the money to be spent. The total
estimated net present value cost to implement the Selected Remedy is $19.4 million.
2.13.4 Utilization of Permanent Solutions and Alternative Treatment (or
Resource Recovery) Technologies to the Maximum Extent Practicable
The EPA has determined that the Selected Remedy represents the maximum extent to
which permanent solutions and treatment technologies can be utilized in a practicable
manner at the Site. Of those alternatives that are protective of human health and the
environment and comply with ARARs, the EPA has determined that the Selected
Remedy provides the best balance of trade-offs in terms of the five balancing criteria,
while also considering the statutory preference for treatment as a principal element and
bias against off-site treatment and disposal and considering State and community
acceptance.
2.13.5 Preference for Treatment as a Principal Element
The NCP establishes a preference for use of treatment to address the principal threats
posed by a site wherever practicable (NCP § 300.430[a][1][iii][A]). The principal threat
concept is applied to the characterization of source materials at a Superfund site. A
source material is material that includes or contains hazardous substances, pollutants
or contaminants that act as a reservoir for migration of contamination to ground water,
surface water, or air; or acts as a source for direct exposure. Principal threat wastes are
those materials considered to be highly toxic or highly mobile that generally cannot be
reliably contained or would present a significant risk to human health or the environment
should exposure occur. Low-level threat wastes are those materials that generally can
be reliably contained and that would present only a low risk in the event of exposure.
The source material at the Site is found in the existing Siphon and the contaminated
sediment located downstream of the Siphon's exit. The Siphon and the contaminated
sediment are not highly toxic or highly mobile, and thus are low-level waste and not
principal threat waste.
The HHRA (EA 2016b) determined that there were no unacceptable human health
concerns for direct contact with sediment containing PCBs. The carcinogenic risks for
the adult, adolescent, and child recreational users are 1x10 7, respectively, which are all
below the lower end of the EPA's target risk range (i.e., 1 x10~6). The total non-
carcinogenic His for the adult, adolescent, and child recreational users are 0.008, 0.03,
and 0.05, respectively, which are all below the EPA's acceptable threshold (i.e., 1.0).
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Also, PCBs are hydrophobic, which means that they tend to bind to sediment particles,
organic matter in sediment, and fatty tissues in biota (EA 2016b). Suspended sediment
in surface water at the Site tends to settle out onto the bottom of the canal system
immediately downgradient of the existing Siphon's exit due to low water velocities
resulting in a gradient of decreasing PCB sediment concentrations with distance from
the Siphon's exit. The Rl (EA 2016a) determined that the highest concentrations of
PCBs were found immediately downgradient of the existing Siphon's exit. As a result,
contaminated sediment is effectively contained within the reservoir and canal system
and is not considered a highly mobile source material.
Additionally, it is likely that the Siphon's construction/repair materials (e.g., concrete,
caulking, grout, or sealants) were a primary source of contamination at the Site. The Rl
(EA 2016a) determined that the concentrations of PCBs in the surface water taken from
within the existing Siphon and analyzed for Total PCB Congeners ranged from 190 to
1,700 picograms/liter (pg/L). These concentrations are well below the federal surface
water quality criteria for aquatic life (i.e., 14,000 pg/L) and the Total PCB maximum
contaminant level for drinking water (i.e., 500,000 pg/L).
2.13.6 Five-Year Review Requirements
Because the implementation of the Selected Remedy will result in hazardous
substances remaining on-Site above levels that allow for unlimited use and unrestricted
exposure, a statutory Five-Year Review will be conducted pursuant to Section 121(c) of
CERCLA and 40 CFR § 300.430(f)(4)(ii) within five years after initiation of the remedial
action to ensure that the remedy is, or will be, protective of human health and the
environment. During the statutory reviews, the EPA will evaluate monitoring data
collected prior to the review period and assess the effectiveness of the Selected
Remedy. If the EPA determines that the RAOs are not being met or that the Selected
Remedy is no longer protective, the remedy will be reevaluated and an Explanation of
Significant Differences document or ROD Amendment may be required.
2.14 DOCUMENTATION OF SIGNIFICANT CHANGES
To fulfill CERCLA §117(b) and the NCP §§300.430(f)(5)(iii)(B) and 300.430(f)(3)(ii)(A),
the ROD must document and discuss the reasons for any significant changes made to
the Selected Remedy. Changes described in this section of the ROD are limited to
those that could have been reasonably anticipated by the public from the time the
Proposed Plan, Rl, and FS were released for public comment to the final selection of
Alternative 6 as the Selected Remedy. Changes that could not have been anticipated
require an additional public comment period.
The Proposed Plan was released for public comment on May 7, 2018. The EPA held
two public meetings on May 22, 2018, in Donna and Alamo, Texas, to present the
Proposed Plan to the public and solicit the public's comments. The public comment
period for the Proposed Plan ended on June 5, 2018. The Proposed Plan identified
Alternative 6 (Replace Siphon, Canal Dredging, and Fish Removals) as the Preferred
Alternative. The EPA reviewed all written and oral comments submitted during the
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public comment period and determined that no significant changes to the Preferred
Alternative, as originally identified in the Proposed Plan, were necessary or appropriate.
Based on the public's comments, the EPA has reconsidered the number offish removal
actions and the performance of an iterative/flexible approach for the remedial action.
The EPA will reevaluate the need to conduct additional fish removals based on the
attainment of the fish tissue RG. Additionally, the EPA has removed references
concerning the performance of an iterative/flexible approach from the ROD and will
perform the remedial action based on the remedial design.
2.15 STATE ROLE
The State of Texas, represented by the TCEQ, was provided the opportunity to review
and comment on the EPA's Selected Remedy (Alternative 6 - Replace Siphon, Dredge
Sediments, and Fish Removals).
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PART 3: RESPONSIVENESS SUMMARY
The Responsiveness Summary summarizes information about the views of the support
agency and the public regarding both the remedial alternatives and general concerns
about the Site submitted during the public comment period. This summary also
documents, in the administrative record, how the public's comments were integrated
into the EPA's decision-making process.
The public meetings announcing the Proposed Plan were held on May 22, 2018, in
Alamo and Donna, Texas. The Proposed Plan described the EPA's rationale for the
selection of the Preferred Alternative. A public comment period for the Proposed Plan
was held from May 7 through June 5, 2018. Public notices of the public meeting and
public comment period were published in two newspapers of general circulation, in
English and Spanish. Additionally, public notices announcing the Proposed Plan, public
meeting, and comment period were mailed to the contacts included in the Site's mailing
list. Representatives from the EPA provided presentations on the Proposed Plan and
answered questions about the EPA's Preferred Alternative. Representatives from the
TCEQ and the Texas Department of State Health Services were also present at the
meeting. Oral and written comments were accepted at the meeting and a court reporter
transcribed the discussions held during the meeting.
The Administrative Record file for the Site; located at the Donna Public Library, TCEQ's
offices, and the EPA's regional office contains all the information and documents
supporting this ROD (see Section 2.3.3 [Information Repositories] of this ROD). This
Administrative Record file includes transcripts of the oral comments received during the
two public meetings held in Donna and Alamo, Texas, on May 22, 2018, by the EPA.
This Administrative Record also contains each of the comments received from the
public through postal or electronic mail.
The majority of the comments received during the public meetings and public comment
period concerning the Proposed Plan were in support of the EPA's Preferred Alternative
6 (i.e., Replace Siphon, Dredge Sediments, and Fish Removals) presented in the
Proposed Plan. The concerns of the community have been considered in the selection
of Alternative 6 as the Selected Remedy for the Site. The following section of this ROD
summarizes the stakeholder's comments, received during the public comment period,
and the EPA's responses to these comments.
3.1 STAKEHOLDER'S COMMENTS AND EPA'S RESPONSES
Comment 1: Where will the sediments removed be taken? Will it continue to impact
human health?
EPA's Response: The sediment dredged/excavated from the canal system,
downgradient of the existing Siphon's exit, will be analyzed for Polychlorinated Biphenyl
(PCB) concentrations and will be disposed in accordance with applicable federal and
state standards for waste disposal at an appropriately permitted landfill. Permitted
landfills are designed to segregate waste and prevent exposure of these materials. The
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specific landfill will be determined during the remedial design or a competitive bid
process.
Comment 2: Since the siphon will be left in place, will it be protected?
EPA's Response: After the construction of a new siphon, the existing Siphon will be
sealed in place (i.e., grouted). A component of the Selected Remedy includes the
implementation of institutional controls (ICs) required to protect the integrity of the
Selected Remedy, which includes providing notification to interested parties of the
existence of the Siphon which likely contains construction materials (e.g., concrete,
caulking, grout, or sealants) containing PCBs.
An IC(s), in the form of a land-use restriction or notice as to the environmental
conditions of the property, would be required that provides restrictions on or notification
of the modifications to the existing Siphon (i.e., grouting in place) and which would
protect the integrity of the remedy. The IC(s) would consist of either a restrictive
covenant or a deed notice. The requirements for filing land use restrictions in the State
of Texas are specified in "30 Texas Administrative Code Chapter 350 Subchapter F,"
under the jurisdiction of the Texas Commission on Environmental Quality. A restrictive
covenant, or deed notice, is an instrument filed in the real property records of the county
where the affected property is located.
Comment 3: How will the EPA distribute information on the Texas Department of
Health Aquatic Life Order #9? Also, can all signs be printed in Spanish and English so
the entire community can understand them?
EPA's Response: The distribution of the information associated with the existing
Aquatic Life Order Number 9 will be a significant component of the community
involvement program established under the Selected Remedy. Due to the
demographics of the local area surrounding the Site, the EPA expects that most of the
information developed for the public under this Record of Decision (i.e., signs,
informative materials, etc.) will be presented in English and Spanish, to the extent
practicable. The specific details of this type of information will be determined during the
remedial design of the Selected Remedy.
Comment 4: Is there any way to let the community know where it is safe to fish?
EPA's Response: The Aquatic Life Order Number 9, maintained by the Texas
Department of State Health Services (TDSHS) since 1994, states that". . . the Donna
Irrigation System [the Site] located in Hidalgo County is declared a prohibited area for
the taking of all species of aquatic life." A map included with the TDSHS' order depicted
the prohibited area for the taking of fish as the canal system extending from the Rio
Grande River to the northern uppermost sections of Donna Lake, which was
investigated by the EPA. Fishing, for recreation, is not directly prohibited under the
order. Figure 1 (Site Location) of the Record of Decision includes a map of the extent of
the reservoir and canal system operated by the Donna Irrigation District (Hidalgo
County No. 1).
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Based on the Human Health Risk Assessment, the EPA has concluded that fish from
the Site are not safe for human consumption and should not be "taken" from the Site
with the intent of consumption. The EPA believes that contaminated fish may be found
within all reaches of the Donna Reservoir and Canal System. The specific details of the
dissemination of information related to fishing in areas other than the Site will be
determined during the remedial design of the Selected Remedy.
Comment 5: Will you be checking remediation progress every five years? It would be
greatly appreciated if you could make this information public.
EPA's Response: The Selected Remedy for the Site will require statutory Five-Year
Reviews, initially beginning five years after the construction of the remedial action, since
contaminants (i.e., PCBs) will be left on-Site above levels that permit unrestricted use
and unlimited exposure. Although the EPA routinely evaluates the remedy, a formal
review will occur every five years in the form of a Five-Year Review Report where the
EPA will evaluate the performance of the remedy (i.e., protectiveness of human health
and the environment). Community involvement and notification is a key component of
the Five-Year Review process. The Five-Year Review Report is a publicly available
agency decision document.
Comment 6: When is the project actually going to start? When would it be over? And if
we had any problems for getting water for the City, because as I heard right now, that's
where they're getting us water right now.
EPA's Response: The actual start date for the implementation of the Selected Remedy
has not been determined. Before its implementation, the remedial design of the
Selected Remedy (i.e., remedial action) will need to be accomplished and can take
several months depending on the complexity of the remedial action. The EPA will make
every effort to begin the implementation of the remedial action as soon as feasibly
possible. Once initiated, the construction time for the remedial action is estimated at
nine months.
The EPA considered the Donna Irrigation District's need to provide, upon demand,
drinking water to the City of Donna and to the North Alamo Water Supply Corporation
Plant No. 5, including providing irrigation water for the surrounding predominantly
agricultural land. At no time during the implementation of the Selected Remedy will the
reservoir and canal system be required to shut down and not be able to supply drinking
or irrigation water to the local community.
Comment 7: I am concerned about the long time line for the completed project and the
possibility of remediation plans being fought in court or slowed to the point of inaction.
The community wants action on this problem.
EPA's Response: The actual start date for the implementation of the Selected Remedy
has not been determined. Before its implementation, the remedial design of the
Selected Remedy (i.e., remedial action) will need to be accomplished and can take
several months depending on the complexity of the remedial action. The EPA will make
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every effort to begin the implementation of the remedial action as soon as feasibly
possible. Once initiated, the construction time for the remedial action is estimated at
nine months. Based on current information, the EPA does not anticipate any possible
court actions regarding the remediation plans.
Comment 8: We also had questions about where the sediment is going to be scraped
off. We understand that there are certain locations that have been pinpointed as high,
but we're wondering if in the reservoir itself where the people go and fish if that will be
scraped, because it has been over 96 years of accumulation of PCBs since 1926.
EPA's Response: The area to be dredged/excavated, under the Selected Remedy's
requirement to meet the sediment cleanup level, spans the width of the Lower West
Main Canal Unlined approximately 4,500 feet beyond the Siphon's exit (i.e., an area
approximately 55 feet wide by 4,500 feet in length). Approximately 20 inches of
sediment will be mechanically dredged/excavated from the canal using clamshell
excavation methods or similar equipment. A volume of approximately 20,000 cubic
yards of sediment will be excavated from the canal. This area has been identified as the
most heavily contaminated area of the Site. PCB concentrations in sediment within this
portion of the canal system decrease with distance from the Siphon's exit; thus,
sediment in the reservoir itself did not have concentrations of PCBs exceeding the
cleanup levels for the sediment and therefore is not planned for removal at this time.
Comment 9: I think it is a good idea to offer free blood testing to local residents even
though there are not clinical reference standards, etc. Some may want to know how
their levels look in comparison with those of typical U. S. residents.
EPA's Response: The EPA does not have the authority to conduct such testing. Blood
testing of residents is a function of the local county/state health departments and the
TDSHS. The EPA recommends that concerned individuals contact these entities to
determine the blood testing options that are available to them.
Comment 10: Why would increased water flow in the siphon have a potential to
increase the PCB concentration?
EPA's Response: The release of PCBs from the Siphon's construction materials (e.g.,
concrete, caulking, grout, or sealants) to surface water from within the interior of the
Siphon occurs slowly but steadily. The water flow rate, be it slow or fast, will not
decrease or increase the rate of release of PCBs into the water column. A faster flow
rate may cause the PCB concentrations in surface water to decrease because the
relatively constant release rate of PCBs from within the Siphon would be diluted even
further. PCBs, being hydrophobic, are not stable in an aqueous environment and are
typically not measured in high concentrations in water, which was determined during the
investigation of the Site. The issue at the Site is not the rate at which PCBs are being
released from the likely source (i.e., the Siphon) into the water column, but the stability
and longevity of the PCBs (i.e., do not easily degrade in the environment), their affinity
to bioaccumulate, and their toxicity.
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Comment 11: The surface water measurements inside the Siphon were taken at
different flow rates (i.e., at the end of the Siphon) and a one-time sampling event is not
sufficient to ID a source. A faster flow rate equates to greater concentrations in surface
water due to turbulence and higher concentrations in suspended particles.
EPA's Response: The likely release of PCBs from the Siphon's construction materials
(e.g., concrete, caulking, grout, or sealants) to surface water from within the interior of
the Siphon occurs slowly but steadily. The water flow rate, be it slow or fast, will not
decrease or increase the rate of release of PCBs into the water column. A faster flow
rate may cause the PCB concentrations in surface water to decrease because the
relatively constant release rate of PCBs from within the Siphon would be diluted even
further. PCBs, being hydrophobic, are not stable in an aqueous environment and are
typically not measured in high concentrations in water, which was determined during the
remedial investigation of the Site. The issue at the Site is not the rate at which PCBs are
being released from the likely source (i.e., the Siphon) into the water column, but the
stability and longevity of the PCBs (i.e., do not easily degrade in the environment), their
affinity to bioaccumulate, and their toxicity.
The EPA's determination that the likely source of contamination at the Site is the
existing Siphon was made based upon the data collected during the remedial
investigation and on the weight of evidence. Sediment data collected during remedial
investigation initially suggested the following options for the location of the source of
PCB contamination at the Site: (1) Between the Siphon's exit and the 90-degree bend
in the Lower West Main Canal Unlined in the area with the most elevated
concentrations of PCBs in sediment, (2) Immediately upgradient of the Siphon's exit and
downgradient of the Main Canal (i.e., in the 160-feet concrete-lined section between the
weir and the Siphon's exit), or (3) No longer present at the Site.
The following additional field investigation activities narrowed down the location of the
likely source of contamination even further:
• The water-based geophysical survey provided targets for further investigation by
the scientific divers in the Lower West Main Canal Unlined. The divers found no
indication of PCB-laden objects in the canal, which eliminates Option 1 (i.e., that
the source of contamination is in the Lower West Main Canal Unlined).
• Surface water samples collected from within the interior of the Siphon and
passive samples collected downgradient of the Siphon's exit indicate that PCBs
persist in the water column upon exiting the Siphon and the concentrations within
the water column decrease with distance from the Siphon's exit. Therefore; these
data indicate that a continuing source of PCB contamination exists at the Site,
which eliminates Option 3 (i.e., that a primary source contamination is no longer
present at the Site).
• The remote-operated vehicle inspection of the Siphon indicates that no foreign
objects which could contain PCBs (e.g., transformers, drums, etc.) are located
within the interior of the Siphon.
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• The hydraulics of the Siphon indicate that most of the time, a positive pressure is
exerted from the interior of the Siphon. Therefore, water would be forced out of
cracks or leaking joints in the Siphon and the chances of contamination leaking
into the Siphon are low.
Therefore, by the weight of evidence from the field investigations, the primary likely
source of PCBs at the Site is located within the inverted Siphon and is not a foreign
object, as described in Option 2.
Comment 12: Are the prohibitions on fishing going to be extended throughout the
whole irrigation system that's being fed by Donna Lake?
EPA's Response: The Aquatic Life Order Number 9, maintained by the TDSHS since
1994, states that". . . the Donna Irrigation System [the Site] located in Hidalgo County is
declared a prohibited area for the taking of all species of aquatic life." A map included
with the TDSHS' order depicted the prohibited area for the taking of fish as the canal
system extending from the Rio Grande River to the uppermost northern sections of
Donna Lake, which was investigated by the EPA. Fishing, for recreation, is not directly
prohibited under the order. Figure 1 (Site Location) of the Record of Decision includes a
map of the extent of the reservoir and canal system operated by the Donna Irrigation
District (Hidalgo County No. 1). The authority to extend the prohibited area for the taking
of fish to the entire Donna Irrigation System is under the jurisdiction of the TDSHS.
Based on the Human Health Risk Assessment, the EPA has concluded that fish from
the Site are not safe for human consumption and should not be "taken" from the Site
with the intent of consumption. The EPA believes that contaminated fish may be found
within all reaches of the Donna Reservoir and Canal System.
Comment 13: Will there be any opportunity for the community to comment on the
design/presentation of signs and educational materials?
EPA's Response: As a component of the Selected Remedy, the EPA will consider the
formation of an advisory group during the remedial design of the Selected Remedy. The
intent for the formation of this group is to work collaboratively with the EPA, and other
appropriate entities, in developing and implementing a community involvement program
which would include the development of signs and educational materials.
Comment 14: Who will pay for the remedial action?
EPA's Response: The EPA's "enforcement first" policy under the Superfund program
requires that the EPA seek potentially responsible parties (PRPs) to fund remedial
action(s) at a site. Whenever possible, through administrative and legal actions, the
EPA requires PRPs to clean up hazardous sites they have contaminated. The EPA will
exhaust its enforcement authority against a PRP(s) before seeking other funding
mechanisms.
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Comment 15: Does the fishing ban apply to the little body of water at La Frontera?
Can EPA install signs at La Frontera?
EPA's Response: The Aquatic Life Order Number 9, maintained by the TDSHS since
1994, states that. . the Donna Irrigation System [the Site] located in Hidalgo County is
declared a prohibited area for the taking of all species of aquatic life." A map included
with the TDSHS' order depicted the prohibited area for the taking of fish as the canal
system extending from the Rio Grande River to the uppermost northern sections of
Donna Lake, which was investigated by the EPA. Fishing, for recreation, is not directly
prohibited under the order. Figure 1 (Site Location) of the Record of Decision includes a
map of the extent of the reservoir and canal system operated by the Donna Irrigation
District (Hidalgo County No. 1).
The EPA is uncertain whether the body of water located near La Frontera is included in
the area subject to the TDSHS' Aquatic Life Order Number 9. However, the EPA
recommends that the community assume that the body of water is included in the order
if it is hydraulically connected to the Donna Reservoir and Canal System from the Rio
Grande River to the uppermost northern sections of Donna Lake. The EPA will consider
installing signs in water bodies hydraulically connected to the reservoir and canal
system during the remedial design of the Selected Remedy.
Comment 16: On page twelve under the Demographic and Cultural Features the
report cites the cities of Donna and Alamo as part of the McAllen-Edinburg-Mission
Metro. While this is correct, there are other data sets including Census block data that
can be used to more properly describe the specific demographic information of the
affected communities including household size, race, income and Limited English
proficiency. The same can be said about what was mentioned on the colonias. More
information is especially important since colonias have comparable differences in the
demographic information, to the metro average, are part of the affected communities,
include higher concentrations of protected classes and are ultimately part of the reason
why the Donna Superfund Site is an environmental justice issue. We recommend using
census tract information to describe the affected areas including the Cities Alamo and
Donna, and surrounding colonias since it is more descriptive than using the metro
regions average.
EPA's Response: The information included in the Demographics and Cultural Features
section of the Proposed Plan was developed during the remedial investigation of the
Site and is included in the Administrative Record file for the Site. As noted in the
comment, the EPA believes that this information is factual and consistent with the main
purpose of the remedial investigation, which is to determine the nature and extent of
contamination at the Site.
Comment 17: On page 13 under Natural Resources and Land Use you cite use of the
canal as "primarily agricultural." It is important to note that the canal is also very popular
among fishermen. The use of the roads that pass through the property and make the
contaminated natural resources accessible should also be included in this section.
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EPA's Response: The EPA, in the Human Health Risk Assessment, considered the
exposure of an adult, adolescent, and a child recreational user to contaminants from the
Site through the ingestion and dermal contact with surface water and sediment, and
ingestion offish. This consideration accounts for anglers that would frequently access
the Site for fishing purposes and includes all areas within the reservoir and canal
system.
Comment 18: We believe that in Alternative 6 (Replace Siphon, Canal
Dredging/Excavation, and Fish Removals), is the most comprehensive of the options
provided however, more should be considered in the proposed plan to make this
solution responsive to the affected communities' needs. One main concern with
Alternative 6 is that the source of the contamination, the siphon, will only be replaced
and not removed from the site. The removal of the source of contaminants and its safe
disposal is a necessary part of a long-term solution and should be included in this
alternative.
EPA's Response: Based on the results of the remedial investigation, the EPA does not
believe that the existing Siphon should be completely removed from the Site. Once the
Selected Remedy is implemented, the existing Siphon will no longer be in contact with
the surface water within the reservoir and canal system and there will be no pathway for
any residual contamination to enter the water. A component of the Selected Remedy is
to dewater the Siphon and to completely seal it in place (i.e., by grouting) to prevent
exposure to human and ecological receptors. Once grouted in place, there will be no
pathway for the PCBs to migrate from the decommissioned Siphon into the reservoir
and canal system.
Soil, sediment, and surface water samples were collected near the Siphon, near the
Arroyo Colorado River, during the remedial investigation and analyzed for PCBs, among
other analytes. The analytical results from samples collected within the Arroyo Colorado
River were evaluated in the human health and ecological risk assessments and did not
indicate a current unacceptable risk to human or ecological receptors from PCBs.
Therefore, the EPA does not expect any unacceptable risks to receptors once the
Siphon is grouted in place and decommissioned.
Comment 19: Under Alternative 6 (Replacement Siphon), the old Siphon should be
completely removed since it would be a continuing source (i.e., outside concrete
structure).
EPA's Response: Based on the results of the remedial investigation, the EPA does not
believe that the existing Siphon should be completely removed from the Site. Once the
Selected Remedy is implemented, the existing Siphon will no longer be in contact with
the surface water within the reservoir and canal system and there will be no pathway for
any residual contamination to enter the water. A component of the Selected Remedy is
to dewater the Siphon and to completely seal it in place (i.e., by grouting) to prevent
exposure to human and ecological receptors. Once grouted in place, there will be no
pathway for the PCBs to migrate from the decommissioned Siphon into the reservoir
and canal system.
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Soil, sediment, and surface water samples were collected near the Siphon, near the
Arroyo Colorado River, during the remedial investigation and analyzed for PCBs, among
other analytes. The analytical results from samples collected within the Arroyo Colorado
River were evaluated in the human health and ecological risk assessments and did not
indicate a current unacceptable risk to human or ecological receptors from PCBs.
Therefore, the EPA does not expect any unacceptable risks to receptors once the
Siphon is grouted in place and decommissioned.
Comment 20: Regarding the second Remedial Action Objective and the Preliminary
Remediation Goal of "reducing or removing the fish from the reservoir," according to the
plan the "objective will be measured by the number, species, and size of the fish
removed from the reservoir and canal system." We agree that the removal of the fish
should be a part of the remediation as they are a human health hazards. We echo
resident concerns on the need for more consistent fish removals. We believe doubling
the suggested amount of one removal a year to biannual removals for five years would
be better for maintaining a low-fish population and deterring anglers. We also suggest
that more specific and measurable goals for the fish removal be identified since they are
needed to understand the efficacy of the remedial efforts.
EPA's Response: Additional fish removals, other than those included in the Selected
Remedy (i.e., annually for five years), may be performed at the Site when appropriate to
meet the Remediation Goal for Total PCBs in fish tissue. The specific details concerning
the timing and measurable key indicators or monitored parameters to determine the
success of the fish removal actions will be determined during the remedial design of the
Selected Remedy.
Comment 21: We agree that deed notifications are important for potential future
buyers to be informed. We also agree with the inclusion of signage "which warn anglers
of the risks associated with the consumption of fish from the Site." We would like to see
more details about the amount of signs that will be posted and where, the design of the
warnings to assure that they are bilingual and culturally relevant, and information on the
party responsible for maintenance and upkeep of the signs, in case they need to be
replaced. Additionally, we suggest that fencing be erected in the areas of the lake and
reservoir that border residential areas in order to deter fishing. The Donna Irrigation
District #1 should be required to reduce the accessibility of their private property, this
includes closing off farm roads used by the public.
EPA's Response: The specific details concerning the signage (e.g., number, design,
and the specific language) will be determined during the remedial design of the
Selected Remedy. Also, due to the demographics of the local area surrounding the Site,
the EPA expects that most of the information developed for the public under this Record
of Decision (i.e., signs, informative materials, etc.) will be presented in English and
Spanish, to the extent practicable. The construction of fencing at the Site, to the extent
practicable, would be considered an engineering control. This type of control will also be
considered during the remedial design of the Selected Remedy.
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Comment 22: Under the Public Outreach and Education section of the plan, the EPA
identifies activities and programs that "may be considered for implementation." Because
remediation has taken so long, we believe that all of the activities and programs
identified for public outreach should be conducted. We echo the community suggestion
for the creation and maintenance of a collaborative working group to develop inclusive
and culturally appropriate outreach and education efforts that includes residents,
advocates, local, state and EPA officials. Previous working groups that met quarterly
(including advocates, residents, local, state and federal official) have shown positive
impacts in community engagement on environmental concerns of the Superfund Site.
We suggest hosting biannual workgroup meetings to coincide with the fish removal
actions. At these meetings the working group can receive updates on remediation and
plan the educational and public outreach.
EPA's Response: As a component of the Selected Remedy, the EPA will consider the
formation of an advisory group during the remedial design of the Selected Remedy. The
intent for the formation of this group is to work collaboratively with the EPA, and other
appropriate entities, in developing and implementing a community involvement program.
The EPA agrees that this group should ideally consist of a diverse group of individuals
to be effective.
Comment 23: While the EPA has noted the increased cancer-hazards to the
surrounding communities, the agency does not provide suggestions for identifying
residents affected directly or the option for residents to test themselves. We request that
the suggested alternative include PCB testing (blood tests) for residents who are
concerned about personal contamination from ingesting the fish in Donna Lake.
EPA's Response: The EPA does not have the authority to conduct such testing. Blood
testing of residents is a function of the local county/state health departments and the
TDSHS. The EPA recommends that concerned individuals contact these entities to
determine the blood testing options that are available to them.
Comment 24: We agree with continuing the enforcement of the "Aquatic Life Order #9"
until the PCB levels in the fish are safe but believe more should be detailed to
understand how Texas Parks and Wildlife Department will enforce the order. A
description of the protocols that the department follows when encountering a fisherman,
educating the public or enforcing the order should be developed. The TPWD should
also conduct weekly visits to the site and maintain a record of said visits.
EPA's Response: The EPA agrees that the maintenance of the existing Aquatic Life
Order Number 9, maintained by the TDSHS, is an essential IC component of the
Selected Remedy. However, the enforcement of this order is outside the scope of the
EPA's jurisdiction and this Record of Decision. As noted in the comment, the
enforcement authority for this order is the Texas Parks and Wildlife Department (i.e.,
Game Warden). A representative of this department was present at the May 22, 2018,
public meeting held in Alamo, Texas, by the EPA to present the Proposed Plan to the
public.
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Comment 25: A water conduit should be constructed over the Arroyo Colorado to
transport water, instead of underneath the Arroyo.
EPA's Response: Flood control levees, under the jurisdiction of the International
Boundary and Water Commission, are located on either side of the Arroyo Colorado
River. The EPA does not have the authority to dictate the construction of the water
conduit. The EPA's authority is limited to addressing the threat and/or actual release of
hazardous substances and contaminants or pollutants.
Comment 26: As the agency moves forward, please emphasize that fishing, boating,
or other access by the public to the District's canals and reservoirs and other
infrastructure is strictly prohibited. It has been impossible for the District to prevent such
public access because of the size, nature, and location of these private structures;
however, access is never authorized without permission. The overall approach to public
education about the dangers of ingesting aquatic life from these water bodies implies
that the prohibited public access is based solely on the associated health risks. In fact,
the public is prohibited from access whether or not such danger is present.
EPA's Response: As a component of the Selected Remedy, the EPA will consider the
formation of an advisory group during the remedial design of the Selected Remedy. The
intent for the formation of this group is to work collaboratively with the EPA, and other
appropriate entities, including the Irrigation District, in developing and implementing a
community involvement program. The issues associated with access could be a topic
for the group's discussion. The EPA does not have authority to prohibit access to
private property. Any Institutional Controls to limit access to the implemented remedy
would have to done in agreement and coordination with affected property owners.
Comment 27: The District also urges EPA to combine the siphon and sediment
remedial work with the International Boundary and Water Commission's (IBWC)
planned Donna Canal Levee Gap Project, which will involve the same infrastructure
covered by EPA's Proposed Plan. Both projects will be paid for primarily with federal
dollars. Both projects will benefit the health and safety of the community - EPA focused
on removing contamination and IBWC focused on protecting the community from
flooding. The District, a local governmental entity, will co-operate and co-ordinate with
both federal entities. Such a holistic approach could be a model for interagency co-
operation for reaching disparate technical goals, while at the same time improving water
delivery to the residents and farms of this area.
EPA's Response: Any issues associated with the International Boundary and Water
Commission's jurisdiction and their planned work and the EPA's implementation of the
Selected Remedy will be considered during the remedial design of the Selected
Remedy.
Comment 28: I believe that dumping source is the cause of pollution for this area.
EPA's Response: The EPA's determination that the likely source of contamination at
the Site is the existing Siphon was made based upon the data collected during the
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remedial investigation and on the weight of evidence. Sediment data collected during
remedial investigation initially suggested the following options for the location of the
source of PCB contamination at the Site: (1) Between the Siphon's exit and the 90-
degree bend in the Lower West Main Canal Unlined in the area with the most elevated
concentrations of PCBs in sediment, (2) Immediately upgradient of the Siphon's exit and
downgradient of the Main Canal (i.e., in the 160-feet concrete-lined section between the
weir and the Siphon's exit), or (3) No longer present at the Site.
The following additional field investigation activities narrowed down the location of the
likely source of contamination even further:
• The water-based geophysical survey provided targets for further investigation by
the scientific divers in the Lower West Main Canal Unlined. The divers found no
indication of PCB-laden objects in the canal, which eliminates Option 1 (i.e., that
the source of contamination is in the Lower West Main Canal Unlined).
• Surface water samples collected from within the interior of the Siphon and
passive samples collected downgradient of the Siphon's exit indicate that PCBs
persist in the water column upon exiting the Siphon and the concentrations within
the water column decrease with distance from the Siphon's exit. Therefore; these
data indicate that a continuing source of PCB contamination exists at the Site,
which eliminates Option 3 (i.e., that a primary source contamination is no longer
present at the Site).
• The remote-operated vehicle inspection of the Siphon indicates that no foreign
objects which could contain PCBs (e.g., transformers, drums, etc.) are located
within the interior of the Siphon.
• The hydraulics of the Siphon indicate that most of the time, a positive pressure is
exerted from the interior of the Siphon. Therefore, water would be forced out of
cracks or leaking joints in the Siphon and the chances of contamination leaking
into the Siphon are low.
Therefore, by the weight of evidence from the field investigations, the primary likely
source of PCBs at the Site is located within the inverted Siphon and is not a foreign
object, as described in Option 2.
Comment 29: I have a concern that the whole irrigation system should have signs,
because the fish are distributed throughout the canals, and people fish in the canals
regularly. I think local residents need to have information about where the irrigation
canals fed by the reservoir are so that they can avoid fishing there. We were told in the
focus groups that the signs should be in the community, not just at the lake; some
commented that signs at the mailboxes in the colonias would be a good idea.
EPA's Response: The Aquatic Life Order Number 9, maintained by the TDSHS since
1994, states that". . . the Donna Irrigation System [the Site] located in Hidalgo County is
declared a prohibited area for the taking of all species of aquatic life." A map included
with the TDSHS' order depicted the prohibited area for the taking of fish as the canal
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system extending from the Rio Grande River to the uppermost northern sections of
Donna Lake, which was investigated by the EPA. Fishing, for recreation, is not directly
prohibited under the order. Figure 1 (Site Location) of the Record of Decision includes a
map of the extent of the reservoir and canal system operated by the Donna Irrigation
District (Hidalgo County No. 1).
Based on the Human Health Risk Assessment, the EPA has concluded that fish from
the Site are not safe for human consumption and should not be "taken" from the Site
with the intent of consumption. The EPA believes that contaminated fish may be found
within all reaches of the Donna Reservoir and Canal System.
The specific details concerning the signage (e.g., number, design, locations, and the
specific language) will be determined during the remedial design of the Selected
Remedy. Also, due to the demographics of the local area surrounding the Site, the EPA
expects that most of the information developed for the public under this Record of
Decision (i.e., signs, informative materials, etc.) will be presented in English and
Spanish, to the extent practicable.
Comment 30: I vigorously support the concept of having input from local community
members living in the area to educational materials and signs. On the working group,
there need to be at least two local residents so that they can support one another when
warranted in making an unexpected point to the rest of the group. That is, the
"community outreach" should be a two-way street, both to and from those who seek to
increase awareness of the prohibition on "keeping" the fish. The local community
members should be people who live near the reservoir, not simply staff members of
community service organizations (who should be included additionally to the local
community members).
EPA's Response: As a component of the Selected Remedy, the EPA will consider the
formation of an advisory group during the remedial design of the Selected Remedy. The
intent for the formation of this group is to work collaboratively with the EPA, and other
appropriate entities, in developing and implementing a community involvement program.
The EPA agrees that this group should ideally consist of a diverse group of individuals,
including local community members, to be effective.
Comment 31: The concepts of "continuous and culturally appropriate outreach and
education," "to include local stakeholders," and "to be created and sustained during
remediation" are all important to assist the community in becoming more aware of the
fish contamination. The EPA should commit to providing bilingual, English and Spanish,
information for all permits required for remediation projects. For example, if the EPA is
required to obtain a Texas Pollutant Discharge Elimination System ("TPDES")
Construction General Permit from the TCEQ, which is likely, the EPA should commit to
providing the requisite Storm Water Pollution Prevention Plan ("SWPPP") in Spanish
and, in addition to posting it at the construction site, maintaining a copy for public
viewing at a local site, such as a library.
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EPA's Response: Due to the demographics of the local area surrounding the Site, the
EPA expects that most of the information developed for the public under this Record of
Decision (i.e., signs, informative materials, etc.) will be presented in English and
Spanish, to the extent practicable. The EPA does not have jurisdiction on whether any
permits required for the implementation of the Selected Remedy are provided in
Spanish. This option would be at the discretion of the permitting authority. Additionally,
any information developed because of the implementation of the Selected Remedy will
be placed in the Administrative Record file for the Site located at the Donna Public
Library, the TCEQ's offices, and the EPA's regional office. This Administrative Record
file contains all the information and documents supporting this Record of Decision (see
Section 2.3.3 [Information Repositories]), and will subsequently include any information
developed during the implementation of the Selected Remedy. Additionally, the EPA will
adhere to any requirements requiring the posting of permits at the construction site.
Comment 32: The HCRMA is the Local Government (LG) sponsor for a transportation
improvement project of a future controlled access freeway called the International
Bridge Trade Corridor (IBTC) (Location Map attached) in which we are currently
undergoing NEPA investigation/clearance activities. Our project development activities
are governed by agreements with Texas Department of Transportation (TxDOT) which
currently has NEPA assignment from FHWA for various types of documents including
environmental assessments (which this project is currently classified). We are in the
initial stages of performing Hazmat Initial Site Assessments and will have eventual
follow-up on a potential IBTC route that traverses the Donna Superfund site. The
HCRMA wanted to make their position known to EPA/TCEQ that we have an interest in
learning more about the proposed Institutional Controls (IC's) discussed at the May 22,
2018 public hearing. The HCRMA believes there are technical means (via design and
specification solutions to our plans package) that can balance safety concerns during
construction and operation — as such we have an interest to discuss proposed project
actions that can achieve development interests within this soon-to-be remediated
Superfund site. We would appreciate being included in future publications, studies,
decisions, and eventual guidance that will govern future Superfund clean-up efforts in
this area.
EPA's Response: The EPA has reviewed the maps provided in the internet links, which
were included with the comment. It appears that the planned bridge construction
activities will occur adjacent to or over the Lower West Main Canal Lined (LWMCL),
Reservoir No. 3 Second Enlargement (West Reservoir or RN3W), and the Northwest
Reservoir. Samples were collected from the LWMCL and RN3W during the remedial
investigation; however, no samples were collected from the Northwest Reservoir.
The EPA recommends that representatives for the Local Government sponsor contact
the EPA's Remedial Project Manager, specified in this Record of Decision, before
construction begins on any portion of the reservoir and canal system to determine if any
actions are warranted to protect human health and the environment. Also, it is the
EPA's understanding that a HCRMA representative has requested to be placed on the
Site's mailing list to receive information concerning the Site.
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Comment 33: We are somewhat concerned about the stated "iterative/flexible
approach." All the elements of Alternative 6 are critically necessary, and there should be
no "flexibility" or wiggle room in replacing the siphon, sealing off the old one, removing
the sediment, and performing regular fish removals.
EPA's Response: After consideration of the public comments received, the EPA has
removed references concerning the performance of an iterative/flexible approach from
the Record of Decision and will perform the remedial action based on the remedial
design.
Comment 34: On page 11 of the Proposed Plan, the EPA identifies the Siphon as the
most likely source of PCB contamination. In the Site History section, on page 5 of the
Proposed Plan, the EPA found that "[t]he Siphon at the Arroyo Colorado River was
constructed underneath the arroyo approximately in 1926 and replaced the original
elevated concrete canal that stretched above the arroyo on concrete pillars." The Donna
Irrigation District Hidalgo County Number One owns the canals, reservoir system, and
the Siphon. The Irrigation District provided the EPA with substantial information
regarding the site's history, including repairs conducted in 1967 to address damage
caused by Hurricane Beulah. The Proposed Plan does not make clear why the Irrigation
District has not been designated as a potentially responsible party, nor does the EPA
appear to have investigated Irrigation District ownership over the years. If the Irrigation
District installed the Siphon, the Irrigation District and not the tax payer should be
responsible for the cost of the site remediation.
EPA's Response: The EPA's "enforcement first" policy under the Superfund program
requires that the EPA seek potentially responsible parties (PRPs) to fund remedial
action(s) at a site. Whenever possible, through administrative and legal actions, the
EPA requires PRPs to clean up hazardous sites they have contaminated. The EPA will
exhaust its enforcement authority against a PRP(s) before seeking other funding
mechanisms.
The EPA has identified the Irrigation District as a PRP through the issuance of a general
notice letter. Additionally, the EPA has issued information requests and has extensively
reviewed historical information to determine ownership of the reservoir and canal
system, including the existing Siphon.
Comment 35: The EPA has identified specific PCB Congeners at the site. The EPA
has identified Aroclor, a trade name for a specific group of PCBs. However, the EPA
does not appear to have used this information to find a potentially responsible party for
the site contamination.
EPA's Response: The EPA's "enforcement first" policy under the Superfund program
requires that the EPA seek potentially responsible parties (PRPs) to fund remedial
action(s) at a site. Whenever possible, through administrative and legal actions, the
EPA requires PRPs to clean up hazardous sites they have contaminated.
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The EPA has identified the Irrigation District as a PRP through the issuance of a general
notice letter. Additionally, the EPA has issued information requests and has extensively
reviewed historical documents to determine ownership of the reservoir and canal
system, including the existing Siphon. A PRP must fall under one of the four statutory
categories of liable parties. These categories include a current owner/operator, past
owner/operator, generator, or transporter. The trade name of a specific group of PCBs
does not necessarily lead to statutorily responsible parties.
Comment 36: On page 6, the Proposed Plan states that the Texas Department of
Health issued an order in 1994, 24 years ago. This order led to the posting of a sign
with the following notice: "Warning, it is illegal to possess fish from this water, fish
caught from this water may contain harmful chemicals." The Proposed Plan does not
make clear whether this sign or any signs are in place and whether these signs are in
Spanish.
EPA's Response: The sign, in English only, warning that it is illegal to possess fish from
the lake was in place during the EPA's latest inspection of the Site, but is uncertain
whether this sign is currently posted. The EPA did observe that several signs in several
sections of the reservoir and canal system, warning of the risks associated with the
consumption of fish, were posted during the EPA's inspection of the Site on May 22,
2018.
Comment 37: On page 8, the EPA states that fish removals have occurred using
electroshocking methods. The EPA proposes no alternative methods for fish removals
and does not appear to have received public input on the electroshocking method.
EPA's Response: Fish removals would be accomplished using electrofishing/shocking
methods. During periods where low water conditions exist at the Site, fish accumulate in
certain areas and could be removed using seine netting or other applicable methods.
Coordination with the Irrigation District would be required to anticipate low water
conditions and plan the fish removals. Other fish removal methods (e.g., hoop, fyke, and
pound nets, etc.) could be used to supplement the removal efforts. Specific details
concerning the fish removals will be determined during the remedial design of the
Selected Remedy.
Comment 38: When conducting fish removal actions, the EPA conducted a public
awareness campaign using newspaper and television. The EPA does not list which
newspapers or television stations were used. For the benefit of affected community
members, the EPA should list the newspapers and televisions stations used and commit
to utilizing the same media outlets for future public awareness campaigns.
EPA's Response: The EPA attempts to utilize local English and Spanish print and
television media for any public announcements of planned activities at the Site. The
EPA did recently request that the public identify specific local media for the
announcement of the release of the Proposed Plan and the date, times, and locations
for the Proposed Plan public meetings.
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Comment 39: On page 9 of the Proposed Plan, EPA states that "approximately 42,553
fish were removed from the Site during the five fish removal actions and disposed of at
an appropriate landfill." PCB-laden fish are hazardous waste pursuant to CERCLA.
Hazardous waste must be disposed of pursuant to the Resource Conservation and
Recovery Act ("RCRA"). Yet, in Table 6 of the Proposed Plan, EPA cites to an
exemption from RCRA for superfund sites. The Proposed Plan does not make clear
whether an "appropriate landfill" is a RCRA permitted landfill or where it is located.
Without a guarantee that hazardous waste fish, soil, and the Siphon will be disposed of
at a RCRA-permitted landfill, the community may face additional environmental issues
resulting from improper disposal.
EPA's Response: Any wastes generated (i.e., sediment, etc.) because of the Selected
Remedy will be analyzed to determine the concentrations of PCBs and will be disposed
of in accordance with applicable state and federal standards and regulations for waste
disposal at an appropriate permitted landfill. Permitted landfills are designed to
segregate waste and prevent exposure of these materials to human and ecological
receptors. The specific landfill will be determined during the remedial design or a
competitive bid process. Permit exemptions only apply to any actions taken on-site at a
specific Superfund site.
Comment 40: On page 11, EPA details a key finding: the Siphon is the most likely
source of the PCB contamination. However, the EPA did not collect samples of the
Siphon materials because of "health and safety concerns, technical challenges, and
high costs." This conclusory sentence does not fully explain why EPA was not able to
collect crucial information in support of its key finding, nor, whether the EPA intends to
test the Siphon upon removal to assure that it is the source of the PCB contamination.
EPA's Response: The EPA may consider the feasibility of obtaining samples from the
Siphon's construction materials (i.e., concrete, caulk, grout, or sealants) during the
remedial design of the Selected Remedy, foremost considering worker safety and the
structural integrity of the Siphon.
Additionally, all options considered for the physical inspection of the interior of the
Siphon introduced the potential to damage the structural integrity of the Siphon. The
Siphon was constructed in approximately 1926 and it is possible that the concrete and
steel used to construct the Siphon may have degraded over time and any direct
physical efforts to sample the Siphon could damage the Siphon.
Comment 41: On page 11, the EPA has included a "Demographics and Cultural
Features" section that fails to discuss cultural features. This section is a listing of
several demographic factors that can be used to characterize the area as poor, and
largely Latin and Spanish speaking. Clearly, the site is used for subsistence and
recreational fishing - a fact EPA does not discuss in this section. Local uses for the
Donna Reservoir and Canal System are similarly missing from this discussion.
Historical value as well as present and past cultural uses and cultural importance, such
as uses by Native Americans, are not discussed.
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EPA's Response: The information included in the Demographics and Cultural Features
section of the Proposed Plan was developed during the remedial investigation of the
Site and is included in the Administrative Record file for the Site. The EPA believes that
this information is consistent with the main purpose of the remedial investigation, which
is to determine the nature and extent of contamination at the Site.
Also, in the Human Health Risk Assessment, the EPA considered recreational and
subsistence fishing during the exposure assessment and developed a Remediation
Goal only for a recreational fisher (i.e., for fish tissue). The EPA also developed a
Preliminary Remediation Goal for an adult subsistence fisher and determined that
removal (i.e., dredging/excavation) of the most heavily contaminated sediment located
downgradient of the Siphon's exit, a component of the Selected Remedy, will be
protective of an adult subsistence fisher (i.e., within the EPA's acceptable cancer risk
range of 10~4 to 10~6), which means that an adult subsistence fisher experiencing the
reasonable maximum exposure estimate for fish consumption has a 1 in 10,000 chance
of developing cancer as a result of Site-related exposure to fish. However, the EPA
does not believe that this is a subsistence community and did not consider a final
Remediation Goal for this scenario in the Record of Decision.
Comment 42: Table 6 states: "The U. S. International Boundary Water Commission
retains right of approval on all improvements which are to pass over, under or through
the walls, levees, improved channel or floodways of U. S. International Boundary and
Water Commission Flood Control Projects, including the Rio Grande." The Proposed
Plan does not discuss efforts by EPA to coordinate with the IBWC on EPA's chosen
Alternative 6, or any public participation allowed at IBWC proceedings. If the IBWC is to
approve the final chosen remediation plan, it is crucial for the impacted communities to
know whether there is the potential for the IBWC to object to EPA's proposal.
EPA's Response: Any issues associated with the International Boundary and Water
Commission's jurisdiction and their planned work and the EPA's implementation of the
Selected Remedy will be considered during the remedial design of the Selected
Remedy.
Comment 43: The EPA recognized the need for institutional controls ("ICs") at the site,
however, as proposed, the EPA leaves the door open for ICs that may not provide
adequate protection for the community. On page 18, the EPA states that "[tjhe IC could
consist of either a restrictive covenant or a deed notice." Restrictive covenants
affirmatively restrict land uses, while deed notices simply put the owner on notice of site
contamination. On page 12, the EPA recognizes at least five colonias by the site.
Colonia residents are especially vulnerable to illegitimate real estate developments
promising affordable homes. Such real estate developers in Texas have been known to
sell homes which sit atop contaminated land, sells homes with no drinking water or
sewage connections, or even sell homes with improperly installed on-site sewage
facilities (septic tanks). This is not to mention other potential uses, such as building
schools, churches, and medical facilities on contaminated soil. This is an intolerable risk
for an already vulnerable community. Allowing deed notices as an option leaves the
door open for future victimization of affected communities. The EPA should require
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restrictive covenants to affirmatively protect the community from future development at
the site.
EPA's Response: The specific details concerning the institutional controls (ICs) to be
implemented at the Site will be determined during the remedial design phase of the
Selected Remedy. The requirements for filing land use restrictions in the State of Texas
are specified in "30 Texas Administrative Code Chapter 350 Subchapter F," under the
jurisdiction of the Texas Commission on Environmental Quality (TCEQ).
Comment 44: My name is [redacted] and I am a retired Border Patrol Agent. I was
stationed in Mercedes Station for many years and am very familiar with the Donna lake
area. During the late 1990's, I reported an illegal dumping incident in this area to the
Texas Natural resource and to the EPA. I never heard anything back from the reported
incident. I believe that this dumping source is the cause of pollution for this area. Call
me when you get a chance or have an EPA investigator call me. My number is
[redacted].
EPA's Response: The EPA appreciates your interest in the Site and the reporting of the
dumping incident. An EPA representative will contact you to discuss this incident.
Comment 45: These comments are on behalf of the Lower Rio Grande Valley Group
of the Sierra Club, and pertain to the EPA remediation plan for the Donna Lake and
Canal System Superfund Site. It has been very frustrating and disheartening to see
EPA remediations efforts proceed so slowly and episodically over so many years. PCBs
were first detected in fish and sediment samples at Donna Lake in 1993, and Donna
Lake has been a Superfund site since 2001. Our members strongly urge EPA to move
ahead now in a timely and efficient manner. This highly toxic site needs to be cleaned
up once and for all so that no more residents are needlessly put in harms way.
We support EPA's Preferred Alternative 6 (replace siphon, canal dredging/excavation,
and fish removals) as it is the most comprehensive alternative for remediation. We have
a couple of recommendations to strengthen Alternative 6. First is to conduct fish
removal twice yearly, rather then yearly. With fish coming into the canal and lake
continually from the Rio Grande, removal once a year is not adequate to guarantee low
enough numbers and small enough fish size to protect local residents. Second,
community outreach and education efforts need to be strengthened and ongoing. This
would be best done by forming a taskforce of local non-profit organizations and
community leaders, and providing them a modest budget to better engage and educate
the surrounding community about the essential importance of not eating any aquatic
organisms from the canal or lake. Just posting signs, as has been shown, is simply not
enough. Third, we are somewhat concerned about the stated "iterative/flexible
approach." All the elements of Alternative 6 are critically necessary, and there should
be no "flexibility" or wiggle room in replacing the siphon, sealing off the old one,
removing the sediment, and performing regular fish removals.
As an aside, we could not find the actual plan with detailed descriptions of the
Alternatives on the Donna Superfund website, which made submitting a comment much
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more difficult than it should have been. This may have decreased the number of online
comments that you received. We look forward to the initiation of your remediation work
in the near future. Please copy us on any progress report or other communication on
this important project.
EPA's Response: The EPA and other State/Federal agencies have been performing
investigations at the Site since PCBs were first detected in fish collected from the Site.
The Site was placed on the EPA's National Priorities List in March 2008, and the EPA
began the remedial investigation of the Site in September 2012. The EPA is now issuing
this Record of Decision to address the risks posed by the contaminants discovered at
the Site.
The EPA agrees that Alternative 6 (Replace Siphon, Canal Dredging, and Fish
Removals) is the most comprehensive alternative to address the contamination at the
Site. Additional fish removals, other than those included in the Selected Remedy (i.e.,
annually for five years), may be performed at the Site when appropriate to meet the
Remediation Goal for Total PCBs in fish tissue. As a component of the Selected
Remedy, the EPA will consider the formation of an advisory group during the remedial
design of the Selected Remedy. The intent for the formation of this group is to work
collaboratively with the EPA, and other appropriate entities, in developing and
implementing a community involvement program. After consideration of the public
comments received, the EPA has removed references concerning the performance of
an iterative/flexible approach from the Record of Decision and will perform the remedial
action based on the remedial design. Also, the EPA will keep the public informed
concerning Site activities through mailings to the Site's mailing list, public notices, and
fact sheets.
Comment 46: I read over the Proposed Plan. Good job! I'm glad to see the preferred
option is total replacement.
EPA's Response: The EPA agrees that Alternative 6 (Replace Siphon, Canal Dredging,
and Fish Removals) is the most comprehensive alternative to address the
contamination at the Site.
Comment 47: / am writing in response to the contaminants in Donna Lake. I live in
Hidalgo County in the city ofEdinburg and have attended presentations about this
problem. It is urgent and imperative that this severe problem be resolved.
I urge the EPA to do Alternative 6. In order to address the threats to human health, this
is the best option by far. It is not only the siphon that needs replacing and the
contaminants that require removal. We also need you to remove the fish regularly and
to monitor this.
The situation is one of "environmental racism" and "environmental justice." We need the
government to fix this problem and ensure people cannot continue to be harmed. Our
local community is impoverished. People will continue to eat the fish in the lake because
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for some people, there is no other food. This is also why information alone does not
work in this situation.
Hidalgo County is a unique environment. I love living here, but I also worry about the
health and safety of my neighbors. Thank you for your attention to this problem.
EPA's Response: The EPA agrees that Alternative 6 (Replace Siphon, Canal Dredging,
and Fish Removals) is the most appropriate alternative to address the contamination at
the Site and for the protection of human health and the environment. The specific
details concerning the timing and measurable key indicators or monitored parameters to
determine the success of the fish removal actions will be determined during the
remedial design of the Selected Remedy.
Comment 48: My vote would be to do nothing. Why should we create a recreational
area to where families can enjoy fishing, lets keep the children in the house playing
destructive video games where they belong. I hope you see that I am jesting, there is no
where close that a family could enjoy an outing without driving to Falcon lake or the gulf.
In fact I have noticed other areas that are dug calechi pits that could be made into a
small lake for fishing. Ask the fish and game folks their livelihoods depend on fishing
license sales. So let's please hurry and fix this problem.
EPA's Response: The Selected Remedy will include a public outreach and educational
program. One of the goals of this program is to reduce the potential risks posed by the
consumption of contaminated fish from the Site by coordinating with the local
communities to identify an alternate fishing location(s) near the Site, routinely stock this
nearby lake/reservoir, and advertise the alternate fishing location. Also, the Remedial
Action Objectives stated in the Record of Decision are intended to reduce the
contaminant levels found in fish tissue at the Site.
Comment 49: The Donna Irrigation District shares the desire to protect public health
and the environment. The Donna Irrigation District does not know how PCBs were
introduced into the Site. The Donna Irrigation District accepts the results of the
environmental characterization performed by the EPA except for the assumption that
the existing siphon is the source of the PCBs. The Donna Irrigation District supports
EPA's plans for institutional and engineering controls (item 1) and performance
monitoring (item 6).
In large part, the District agrees with EPA's plans for public outreach and education
(Item 2), with one clarifying comment. The Proposed Plan considers:
Reducing the potential risks posed by consumption of contaminated fish from the
Site by coordinating with the local communities to identify an alternate fishing
location(s) near the Site, routinely stock this nearby lake/reservoir, and advertise
the alternate fishing location.
The consideration quoted above implies that EPA equates fishing in an "alternate
fishing location," which one assumes would be on public property, with fishing on the
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District's private property. While the Proposed Plan makes a passing reference to the
District's "private property," the District would like to see a stronger statement about how
accessing the District's canal and reservoir system is trespass.
EPA's Response: The EPA does not have the authority to enforce private property
rights and trespass laws. The description of fishing is simply of the activities that have
been observed at the Site and not a determination of public versus private access to
fishing locations.
Comment 50: The Donna Irrigation District supports plans for fish removal activities
(item 3) and also supports the citizen suggestion made at the Alamo City Public Hearing
on May 23, 2018, which recommended performing two fish removal events annually
rather than one. The District agrees that this would expedite eliminating contaminated
fish from the canal and reservoir system and reduce the potential risk of public
exposure.
The Donna Irrigation District does not fully support the sediment removal plan (item 4),
and siphon replacement (item 5) as discussed below.
Regarding the planned sediment removal in the Lower West Main Canal Unlined portion
of the canal system downstream of the discharge from the siphon (item 4), the Donna
Irrigation District requests the following:
• In Figure 4, Sediment Remediation Area, the Proposed Plan shows the
extent of the area planned for sediment removal. It appears that there is
about 1,000 feet of canal distance between the last "clean" sample (clean
as defined by EPA as a sample with a PCB concentration that is less than
the Cleanup Goal of 0.043 mg/kg) that defines the downstream extent of
the remediation area and the next upstream sample that is impacted by
PCBs at a concentration greater than 0.043 mg/kg. The Donna Irrigation
District requests that the EPA perform additional sediment
characterization sampling between these two points with the objective of
decreasing the extent of the sediment remediation area and realizing the
associated cost savings due to potentially less sediment removal.
• The Proposed Plan includes stabilization, transportation and offsite
disposal of the estimated 20,000 cubic yards of sediment that is planned
to be removed from the canal. The cost estimates in the Feasibility Study
Report include $596,589 for onsite stabilization of the sediment with
Portland cement, $995,944 for transportation to the landfill (includes
transport and driver expenses), and $2,180,692 for disposal at the landfill.
The Donna Irrigation District requests that the EPA evaluate modifying the
plan to include mixing the removed sediment with Portland cement onsite
and placing the material back in the bottom of the canal to form a lining
where it could serve as a barrier to infiltration of canal water into the
underlying soil. Mixing the removed sediment with Portland cement would
alter the sediment in a manner that would limit the bioavailability of the
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PCBs. The PCBs in the cement mixture would not be expected to
solubilize into the canal water due to the hydrophobic physical
characteristic of PCBs. Additionally, lining the bottom of the canal with the
sediment and cement mixture would conserve water in the future by
decreasing infiltration into the underlying soil. This modified approach
could decrease the cost for implementation of the response action and
increase water conservation.
As a variation on this approach of mixing the removed sediment with
cement and using the material to line the bottom of the canal where the
excavation is performed, the sediment with the greater concentrations of
PCBs could be sent for off site disposal and that portion of sediment with
PCB concentrations above the cleanup goal but still relatively low could be
used in the sediment-cement mixture for lining the canal bottom.
EPA's Response: Additional fish removals, other than those included in the Selected
Remedy (i.e., annually for five years), may be performed at the Site when appropriate to
meet the Remediation Goal for Total PCBs in fish tissue.
The EPA will perform confirmation sampling during the dredging/excavation of
contaminated sediment to ensure that the Remedial Action Objective for the removal of
contaminated sediment is met. Based on confirmation sampling, the extent of
contaminated sediment, located downstream of the Siphon's exit, may be more or less
than the areal extent identified in the Proposed Plan and this Record of Decision.
Concerning the mixing of the removed sediment with Portland cement and placement in
the bottom of the canal "to form a lining where it could serve as a barrier" would not be
appropriate for this Site since any barrier could be damaged in the future and pose
additional threats and/or actual releases of contaminants. The Irrigation District
performs periodic maintenance of the earthen canals (i.e., dredging/excavation of
sediment) as the need arises. Periodic maintenance includes removal of soft sediment
and material that accumulates on the bottom of the canals. Material is mechanically
removed from the canals and placed on the canal levee banks. The Irrigation District
performed maintenance in 1990 and 1991 at the Lower West Main Canal Unlined from
the Siphon's exit to the Lower West Main Canal Lined. Other maintenance operations
may have subsequently occurred as needed during the operation of the reservoir and
canal system. According to the Irrigation District, additional maintenance of the reservoir
and canal system may also be needed in the future. This maintenance is required to
maintain reservoir and canal capacity and flow.
Comment 51: The Donna Irrigation District disagrees with the EPA's statement that the
Donna Irrigation District owns the existing siphon or all of the underlying property. The
Donna Irrigation District has extensively researched record title of the property on which
the siphon is located, including easements. This information has been provided to EPA
in a third supplemental response to EPA's original information request. As part of the
International Boundary Water Commission (IBWC) Flood Control Projects, the IBWC
obtained floodway easements including portions of the Main Canal from the Cinco
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Check in the south to the Norwood Gate in the north. The IBWC Flood Control Project
was necessary for the Federal Floodway System to provide flood relief to the Lower Rio
Grande Valley. Facilities located within the floodway area where the IBWC holds
easements are controlled by the IBWC. The ownership of any fee title in the IBWC
Flood Control Project, including any ownership by Donna Irrigation District, is subject to
the IBWC floodway easements. Any exercise of fee ownership rights cannot interfere
with the easement rights held by the IBWC. The easements granted for the Floodway
System cannot be trespassed upon without permits from the IBWC. As the easements
holder, the IBWC is responsible for maintaining the floodway system so as not to
interrupt water diverted from the Rio Grande in the floodway area for delivery to the
Donna Irrigation District's customers, which includes flow through the siphon and Main
Canal. If the siphon somehow interferes with the Donna Irrigation District's delivery of
water to its customers, the Donna Irrigation District would have recourse against the
IBWC for such interference. However, if the Donna Irrigation District exercised self-help
to address such interference without agreement of the IBWC, it would be deemed a
trespasser. In summary, the Donna Irrigation District does not own all of the property
where the existing siphon is located nor does it own the siphon.
EPA's Response: The EPA continues to proceed with its CERCLA enforcement and
determination of appropriate responsible parties for the Site. The EPA will make final
determinations on responsible parties when appropriate. The ownership language has
been changed in the Record of Decision to reflect the Donna Irrigation District's control
of the reservoir and canal system.
Comment 52: The EPA has concluded that the existing siphon is the likely source of
PCBs at the Site. The EPA has stated in the Proposed Plan: "The likely source of PCB
contamination at the Site has been determined to be the Siphon, based on an
evaluation of the data collected during the Ri and by deduction and weight of evidence."
This conclusion appears to be based predominately on the limited water sampling
conducted inside the siphon and the lack of other potential sources such as PCB
containers or electrical equipment. The Donna Irrigation District considers the water
sampling and analysis for PCBs inside the siphon to be inconclusive because it was a
one-time sampling event with samples collected at two different volumetric flowrates in
the siphon. Seven of the samples were collected during a siphon flowrate of 40 cubic
feet per second and three of the samples, those with the highest reported PCB
concentrations, were collected during a siphon flowrate of 100 cubic feet per second
according to Figure 4-31 in the Feasibility Study Report. The EPA has not explained if
the increased flowrate in the siphon caused the higher PCB concentrations in the water
samples due to increased suspended sediment or other factors. The EPA also has not
explained how PCB concentrations in the picograms (1x1 Ct12 grams) per liter range in
the water could result in PCB concentrations in the sediment at the milligrams (1x106
grams) per kilogram level.
EPA's Response: The likely release of PCBs from the Siphon's construction materials
(e.g., concrete, caulking, grout, or sealants) to surface water from within the interior of
the Siphon occurs slowly but steadily. The water flow rate, be it slow or fast, will not
decrease or increase the rate of release of PCBs into the water column. A faster flow
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rate may cause the PCB concentrations in surface water to decrease because the
relatively constant release rate of PCBs from within the Siphon would be diluted even
further. PCBs, being hydrophobic, are not stable in an aqueous environment and are
typically not measured in high concentrations in water, which was determined during the
remedial investigation of the Site. The issue at the Site is not the rate at which PCBs are
being released from the likely source (i.e., the Siphon) into the water column, but the
stability and longevity of the PCBs (i.e., do not easily degrade in the environment), their
affinity to bioaccumulate, and their toxicity.
The EPA's determination that the likely source of contamination at the Site is the
existing Siphon was made based upon the data collected during the remedial
investigation and on the weight of evidence. Sediment data collected during remedial
investigation initially suggested the following options for the location of the source of
PCB contamination at the Site: (1) Between the Siphon's exit and the 90-degree bend
in the Lower West Main Canal Unlined in the area with the most elevated
concentrations of PCBs in sediment, (2) Immediately upgradient of the Siphon's exit and
downgradient of the Main Canal (i.e., in the 160-feet concrete-lined section between the
weir and the Siphon's exit), or (3) No longer present at the Site.
The following additional field investigation activities narrowed down the location of the
likely source of contamination even further:
• The water-based geophysical survey provided targets for further investigation by
the scientific divers in the Lower West Main Canal Unlined. The divers found no
indication of PCB-laden objects in the canal, which eliminates Option 1 (i.e., that
the source of contamination is in the Lower West Main Canal Unlined).
• Surface water samples collected from within the interior of the Siphon and
passive samples collected downgradient of the Siphon's exit indicate that PCBs
persist in the water column upon exiting the Siphon and the concentrations within
the water column decrease with distance from the Siphon's exit. Therefore; these
data indicate that a continuing source of PCB contamination exists at the Site,
which eliminates Option 3 (i.e., that a primary source contamination is no longer
present at the Site).
• The remote-operated vehicle inspection of the Siphon indicates that no foreign
objects which could contain PCBs (e.g., transformers, drums, etc.) are located
within the interior of the Siphon.
• The hydraulics of the Siphon indicate that most of the time, a positive pressure is
exerted from the interior of the Siphon. Therefore, water would be forced out of
cracks or leaking joints in the Siphon and the chances of contamination leaking
into the Siphon are low.
Therefore, by weight of evidence from the field investigations, the primary likely source
of PCBs at the Site is located within the inverted Siphon and is not a foreign object, as
described in Option 2.
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Comment 53: Before proceeding with siphon replacement, it should be conclusively
established through further sampling whether the siphon is a source of the PCBs rather
than the source being a spill or dumping of a PCB containing liquid into the canal at the
siphon outfall. The Donna Irrigation District has noted the EPA's stated intention to
implement an iterative/flexible approach to address the uncertainty with the siphon as a
source of the PCBs at the Site. The Donna Irrigation District supports EPA's stated
approach to implement the sediment and fish removal activities prior to addressing the
siphon. If the EPA continues to believe that the siphon is an ongoing source of PCBs,
the Donna Irrigation District supports the EPA's stated plan to sample the caulk and
sealant on the interior of the siphon to confirm the presence or absence of PCBs before
beginning remedial action on the siphon. The Donna Irrigation District takes the position
that this sampling is necessary before the EPA proceeds with spending the significant
amount of money ($8,100,000 according to the Feasibility Study Report) estimated for
the siphon replacement.
EPA's Response: After consideration of the public comments received, the EPA has
removed references concerning the performance of an iterative/flexible approach from
the Record of Decision and will perform the remedial action based on the remedial
design.
Comment 54: If further sampling confirms that the existing siphon is the source of the
PCBs, the Proposed Plan for siphon replacement includes closure in place of the
existing siphon after a new siphon is constructed. The Donna Irrigation District requests
that EPA remove the existing siphon rather than closing it in place. Leaving the existing
siphon would result in an ongoing potential future liability due to possible future
deterioration of the existing siphon and the possible migration of PCBs, if EPA confirms
that PCBs are present. If the EPA determines that it is warranted to spend millions of
dollars replacing the existing siphon, the Donna Irrigation District requests that the EPA
achieve clean closure by removing the existing siphon.
The IBWC is beginning the process needed to close a gap in its floodway levee
intersecting the Donna Irrigation District Lower West Main Canal unlined south of the
Norwood Gate, and north of the existing siphon. Under discussion is construction
involving the canal area with the highest reported concentrations of PCBs and
replacement or extension of the existing siphon. This information has previously been
provided to EPA. Donna Irrigation District requests that EPA coordinate closely with the
IBWC to ensure consistency, efficiency, and cost savings. If the EPA is planning to
construct a new siphon and the IBWC is planning to extend the siphon so that its outfall
is outside the boundary of the flood control levees, the most cost-effective approach
would be to combine the two projects into one construction event. This approach would
support a long-term solution that addresses both environmental and flood control
objectives.
EPA's Response: Based on the results of the remedial investigation, the EPA does not
believe that the existing Siphon should be completely removed from the Site. Once the
Selected Remedy is implemented, the existing Siphon will no longer be in contact with
the surface water within the reservoir and canal system and there will be no pathway for
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any residual contamination to enter the water. A component of the Selected Remedy is
to dewater the Siphon and to completely seal it in place (i.e., by grouting) to prevent
exposure to human and ecological receptors. Once grouted in place, there will be no
pathway for the PCBs to migrate from the decommissioned Siphon into the reservoir
and canal system.
Soil, sediment, and surface water samples were collected near the Siphon, near the
Arroyo Colorado River, during the remedial investigation and analyzed for PCBs, among
other analytes. The analytical results from samples collected within the Arroyo Colorado
River were evaluated in the human health and ecological risk assessments and did not
indicate a current unacceptable risk to human or ecological receptors from PCBs.
Therefore, the EPA does not expect any unacceptable risks to receptors once the
Siphon is grouted in place and decommissioned.
Any issues associated with the International Boundary and Water Commission's
jurisdiction and its planned work and the EPA's implementation of the Selected Remedy
will be considered during the remedial design of the Selected Remedy.
Comment 55: The Donna Irrigation District requests that the EPA, and its consultants
and contractors, continue to coordinate their activities with the Donna Irrigation District
to minimize disruption to its operations. Additionally, if the EPA determines that a
remedial action is warranted for the existing siphon and moves forward with the portion
of the Proposed Plan to replace the siphon, the Donna Irrigation District requests that
the EPA coordinate with the Donna Irrigation District to minimize disruptions in canal
system operations. For example, it would be advantageous to perform construction or
sediment remediation in the October to December timeframe when typical irrigation
water flowrates are relatively lower than during other months of the year.
EPA's Response: The EPA's collaboration and coordination with the Irrigation District
will be important aspects of the remedial actions taken under the Selected Remedy.
Comment 56 (This identical comment was received separately by approximately
fifty individuals from several cities): I am a resident of Alamo, Texas (several cities
were included with this comment). I am concerned about the PCB contamination of the
Donna Lake Superfund Site. I support the suggested solution (Alternative 6) but believe
it can be improved. I stand along community members advocating for the following to be
included in the Record of Decision:
1. PCB testing for residents concerned about potential contamination,
2. The creation of a community work group to advise concerning public outreach
and education, and
3. Conduct fish removals twice a year for five years.
Thank you for your consideration and let's work together to clean up the Donna Lake.
Sincerely, (Several individuals included this identical comment).
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EPA's Response: The EPA does not have the authority to conduct such testing. Blood
testing of residents is a function of the local county/state health departments and the
TDSHS. The EPA recommends that concerned individuals contact these entities to
determine the blood testing options that are available to them.
As a component of the Selected Remedy, the EPA will consider the formation of an
advisory group during the remedial design of the Selected Remedy. The intent for the
formation of this group is to work collaboratively with the EPA, and other appropriate
entities, in developing and implementing a community involvement program.
Additional fish removals, other than those included in the Selected Remedy (i.e.,
annually for five years), may be performed at the Site when appropriate to meet the
Remediation Goal for Total PCBs in fish tissue. The specific details concerning the
timing and measurable key indicators or monitored parameters to determine the
success of the fish removal actions will be determined during the remedial design of the
Selected Remedy.
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REFERENCES
Dynamac Corporation. 2013. Removal Report for Donna Main Canal, Donna, Hidalgo
County, Texas. June.
EA Engineering, Science and Technology, Inc., PBC (EA). 2016a. Remedial
Investigation Report, Revision 01, Remedial Investigation/Feasibility Study,
Donna Reservoir and Canal System, Donna, Hidalgo County, Texas. March.
. 2016b. Human Health Risk Assessment, Revision 02, Remedial
Investigation/Feasibility Study, Donna Reservoir and Canal System, Donna,
Hidalgo County, Texas. March.
. 2016c. Ecological Risk Assessment, Revision 03, Remedial
investigation/Feasibility Study, Donna Reservoir and Canal System, Donna,
Hidalgo County, Texas. March.
. 2016d. Feasibility Study, Revision 01, Remedial investigation/Feasibility
Study, Donna Reservoir and Canal System, Donna, Hidalgo County, Texas.
July.
El-Hage, A. and Moulton, D. 2000. Ecologically Significant River and Stream
Segments of the Rio Grande (Region M) Water Planning Area. Accessed 27
November:
http://www.tpwd.state.tx.us/publications/pwdpubs/pwd rp t3200 1059e/index.p
html.
Jahrsdoerfer, S.E. and Leslie, Jr., D.M. 1988. Tamaulipan brushland of the Lower Rio
Grande Valley of south Texas: description, human impacts, and management
options. U.S. Fish and Wildlife Service. Biological Report 88(36). November.
MacWhorter, William. 2015. Lower Rio Grande Valley National Wildlife Refuge.
Handbook of Texas Online. Accessed 02 September at:
http://www.tshaonline.org/handbook/online/articles/gkl25.
McCoy, W. 1990. Evaluation of Ground-Water Resources in the Lower Rio Grande
Valley, Texas. Texas Water Development Board Report 316. Austin, Texas.
January.
Sauls, J.W. 2008. The Texas Citrus Industry. Accessed 27 October at:
http://aggie-horticulture.tamu.edu/citrus/l2286.htm.
Texas Comptroller of Public Accounts. 2008. Texas in Focus: South Texas. Available
online:
http://www.window.state.tx.us/specialrpt/tif/southtexas/sidebars/agriculture.html
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Texas Natural Resource Conservation Commission (TNRCC). 1998. Polychlorinated
Biphenyls in Donna Reservoir and Contiguous Waters, Results of Intensive
Sediment, Water and Fish Sampling and Human Health Risk Assessment.
Austin, Texas. October.
. 2001. Screening Site Inspection Report, Donna Reservoir and Canal System,
Donna, Hidalgo County, Texas. Superfund Site Discovery and Assessment
Program.
Texas Secretary of State. 2011. Texas Border & Mexican Affairs; Directory of Colonias
Located in Texas. Accessed 12 October 2011.
http://www.sos.state.tx.us/border/colonias/reg-colonias/index.shtml
URS Corporation. 2006. Feasibility Study Report. Donna Reservoir and Canal
System, Donna Hidalgo County, Texas. Prepared for Texas Commission on
Environmental Quality. June.
U.S. Census Bureau. 2000. Profile of Selected Economic Characteristics. Donna City,
Texas and State and County Quick Facts. Accessed 12 October 2011.
http://www.census.gov/.
. 2010a. Profile of General Population and Housing Characteristics. Donna
City, Texas and Profile of General Population and Housing Characteristics.
McAllen-Edinburg-Mission, TX Metro Area. Accessed 12 October 2011.
http://www.census.gov/.
. 2010b. Profile of General Population and Housing Characteristics. Alamo City,
Texas and Profile of General Population and Housing Characteristics. McAllen-
Edinburg-Mission, TX Metro Area. Accessed 25 January 2016.
http://www.census.gov/.
. 2010-2014 American Community Survey 5-Year Estimates. Income in the Past
12 Months (In 2014 Inflation-Adjusted Dollars). Alamo City, Texas and Profile
of General Population and Housing Characteristics. McAllen-Edinburg-Mission,
TX Metro Area. Accessed 25 January 2016. http://www.census.gov/.
U.S. Department of Agriculture. 1981. Soil Survey of Hidalgo County, Texas. Soil
Conservation Service in cooperation with the Texas Agricultural Experiment
Station.
U.S. Environmental Protection Agency (EPA). 1990. National Oil and Hazardous
Substances Pollution Contingency Plan (40 Code of Federal Regulation Part
300).
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. 1994. Lower Rio Grande Valley Environmental Monitoring Study, Report to the
Community on the Pilot Project. June.
. 2004. Risk Assessment Guidance for Superfund. Volume I: Human Health
Evaluation Manual (Part E: Supplemental Guidance for Dermal Risk
Assessment). Final. Office of Superfund Remediation and Technology
Innovation. EPA-540-R-99-005. July
. 2005. Contaminated Sediment Remediation Guidance for Hazardous Waste
Sites. EPA-R-05-012. OSWER 9355.0-85. December.
. 2008. National Priorities List. Final Site: Donna Reservoir and Canal System,
Donna Texas, Hidalgo County. OSWER/OSRTI State, Tribal, and Site
Identification Branch. Washington, DC. March.
. 2013. Polychlorinated Biphenyls Basic Information. Available online at:
http://www3.epa.gov/epawaste/hazard/tsd/pcbs/about.htm.
. 2016. Community Involvement Plan, Donna Reservoir and Canal System,
Donna Hidalgo County, Texas. Region 6. February.
U.S. Geological Survey (USGS). 2002. Occurrence of Polychlorinated Biphenyls on
Suspended Sediment in the Donna Canal, Hidalgo County, Texas, 1999-2001.
USGS Fact Sheet 016-02.
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TABLES
000750
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Table 1
Measurement Endpoints for Ecological Risk Assessment
Assessment Endpoint
Measurement Endpoint
On Site-Measurements/Exposure Point
Concentrations (EPC)
Evaluation Method
Risk Indicators
Initial screening.
• Maximum surface soil concentrations measured at
site in past and more Tecent sampling.
• Direct comparison to the TCEQ ecological screening
levels (2014) to define COPCs.
• Chemicals defined as COPCs indicate the potential
for risk.
Protection of terrestrial plant viability from impacts
of COPCs in surface soil
Comparison of surface soil concentrations to
benchmarks.
• Maximum and 95%UCL mean surface soil
concentrations measured at site in past and more
recent sampling.
• Direct comparison of maximum surface soil
concentrations to plant benchmarks (TRVs).
• Direct comparison of mean surface soil concentrations
and individual concentrations against TRVs.
• Plant benchmarks from
1) USEPA EcoSSLs
2) ORNL benchmarks (Efroymson et al. 1997a).
• Exceedance of benchmarks indicates potential for
risks.
Comparison of surface soil concentrations to
background surface soil concentrations.
• Maximum and 95% UCL mean surface soil
concentrations measured at site in past and more
recent sampling.
• Direct comparison to background concentrations.
• Exceedance of background indicates
contaminants are not naturally occurring or
widely distributed across the entire area.
• Exceedance of benchmarks and background
indicates a more certain potential for risk.
Initial screening.
• Maximum surface soil concentrations measured at
site in past and more recent sampling.
• Direct comparison to the TCEQ ecological screening
levels (2014) to define COPCs.
• Chemicals defined as COPCs indicate the potential
for risk.
Protection of soil invertebrates exposed to COPCs
in surface soil from adverse survival, growth and
reproductive effects
Comparison of surface soil concentrations to
benchmarks.
• Maximum and 95% UCL mean surface soil
concentrations measured at site in past and more
recent sampling.
• Direct comparison of maximum surface soil
concentrations to invertebrate benchmarks.
• Direct comparison of mean surface soil concentrations
and individual concentrations to invertebrate benchmarks.
• Invertebrate benchmarks from
1) USEPA EcoSSLs
2) ORNL benchmarks (Efroymson et al. 1997b).
• Exceedance of benchmarks indicates potential for
risks.
Comparison of surface soil concentrations to
background surface soil concentrations.
• Maximum and 95% UCL mean surface soil
concentrations measured at site in past and more
recent sampling.
• Direct comparison to background concentrations.
• Exceedance of background indicates
contaminants are not naturally occurring or
widely distributed across the entire area.
¦ Exceedance of benchmarks and background
indicates a more certain potential for risk.
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas Record of Decision
000751
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Table 1
Measurement Endpoints for Ecological Risk Assessment
Assessment Endpoint
Measurement Endpoint
On Site-Measurements/Exposure Point
Concentrations (EPC)
Evaluation Method
Risk Indicators
Initial screening.
• Maximum sediment and surface water
concentrations measured at site in past and more
recent sampling.
• Direct comparison to the TCEQ ecological screening
levels (2014) to define COPCs.
• Chemicals defined as COPCs indicate the potential
for risk.
Protection of benthic invertebrates and aquatic
organisms exposed to COPCs in sediment and
surface water from adverse survival, growth and
reproductive effects
Comparison of sediment and surface water
concentrations to benchmarks.
• Maximum and 95% UCL mean sediment and
surface water concentrations measured at site in past
and more recent sampling.
• Compare maximum mean, and individual sediment
concentrations against benthic TRVs (consensus based
benchmarks from literature-based studies).
• Compare maximum, mean, and individual surface water
concentrations against aquatic TRVs (consensus based
benchmarks from literature-based studies).
• Exceedance of benchmarks indicates potential for
risks.
Comparison of surface water and sediment
concentrations to background surface water and
sediment concentrations.
• Maximum and 95% UCL mean surface water and
sediment concentrations measured at site in past and
more recent sampling.
• Direct comparison to background concentrations.
• Exceedance of background indicates
contaminants are not naturally occurring or
widely distributed across the entire area.
• Exceedance of benchmarks and background
indicates a more certain potential for risk.
Initial screening.
• Surface soil and surface water concentrations
measured at site in past and more recent sampling.
• Direct comparison to the TCEQ ecological screening
levels (2014) to define COPCs.
• Chemicals defined as COPCs indicate the potential
for risk.
Protection of terrestrial mammals and birds to
ensure that ingestion of COPCs in surface soil,
surface water, and plants/prey do not have
unacceptable impacts on survival, growth, and
reproduction
Comparison of modeled food web doses to
benchmarks.
• Maximum and 95% UCL mean surface soil and
surface water concentrations measured at site in past
and more recent sampling.
• Maximum and 95% UCL mean food item tissue
concentrations modeled using literature-based
equations.
• Maximum and 95% UCL mean ingested dose
based on literature-based exposure factors and
uptake equations.
• Calculate maximum case scenario doses using food web
models and compare to no- and low-effects benchmarks.
• Calculate mean case scenario doses and compare to no-
and low-effects benchmarks.
• Mammal and bird dose-based benchmarks from
1) USEPA EcoSSL
2) ORNL benchmarks (Sample et al. 1998)
3) Additional literature-based sources as relevant.
• Exceedance of benchmarks indicates a potential
for risks.
• Exceedance of low-effects benchmarks indicates a
more certain potential for risks.
Comparison of surface soil and surface water
concentrations to background surface soil and
surface water concentrations.
• Maximum and 95% UCL mean surface soil and
surface water concentrations measured at site in past
and more recent sampling
• Direct comparison to background concentrations.
• Exceedance of both benchmarks and background
indicates a more certain potential for risks.
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas Record of Decision
000752
-------
Table 1
Measurement Endpoints for Ecological Risk Assessment
Assessment Endpoint
Measurement Endpoint
On Site-Measurements/Exposure Point
Concentrations (EPC)
Evaluation Method
Risk Indicators
Initial screening.
• Maximum sediment and surface water
concentrations measured at site in past and more
recent sampling.
• Direct comparison to the TCEQ ecological screening
levels (2014) to define COPCs.
• Chemicals defined as COPCs indicate the potential
for risk.
Protection of aquatic-feeding mammals and birds, to
ensure that ingestion of COPCs in sediment, surface
water, and food do not have adverse impacts on
survival, growth, and reproduction
Comparison of modeled food web doses to
benchmarks.
• Sediment and surface water concentrations
measured at site in past and more recent sampling
- SLERA: Maximum Concentrations
- Refined SLERA & BRAPF: Mean
Concentrations
• Aquatic food item tissue concentrations modeled
using literature-based equations
- SLERA: Maximum Concentrations
- Refined SLERA & BRAPF: Mean
Concentrations
• Ingested dose based on literature-based exposure
factors and uptake equations
- SLERA: Maximum Dose
- Refined SLERA & BRAPF: Mean Dose
• Calculate maximum case scenario doses using food web
models and compare to no-effects benchmarks.
• Calculate mean case scenario doses and compare to no-
and low-effects benchmarks.
• Bird dose-based benchmarks from
1) USEPA EcoSSL
2) ORNL benchmarks (Sample et al. 1998)
3) Additional literature-based sources as relevant.
• Exceedance of benchmarks indicates a potential
for risks.
• Exceedance of low-effects benchmarks indicates a
more certain potential for risks.
Comparison of surface water and sediment
concentrations to background surface water and
sediment concentrations.
• Sediment and surface water concentrations
measured at site and in background areas
- Refined SLERA & BRAPF: Maximum and
Mean Concentrations
• Plant food item tissue concentrations modeled
using literature-based equations
- Refined SLERA & BRAPF: Maximum and
Mean Concentrations
• Ingested dose based on literature-based exposure
factors and uptake equations
- Refined SLERA & BRAPF: Maximum and Mean
Dose
• Compare maximum and mean case scenario doses on-
site to doses calculated for background areas.
• Exceedance of both benchmarks and background
indicates a more certain potential for risks.
Protection of reptiles and amphibians to ensure that
ingestion of COPCs in surface soil, sediment,
surface water, and prey do not have unacceptable
impacts on survival, growth, and reproduction
Comparison of modeled food web doses to
benchmarks.
• EPCs evaluated for other receptors.
• Evaluate whether other wildlife receptors are at risk and
consider results as surrogate for reptiles.
• Risks from COPCs to other receptors indicate that
there may be a risk to reptiles and amphibians from
the same COPCs.
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas Record of Decision
000753
-------
Table 2
Threatened and Endangered Species that may be found in Hidalgo County
Common Name
Scientific Name
Federal
Status
State Status
Surrogate Species
Birds
American Peregrine Falcon
Falco peregrinus anatum
Delisted
Threatened
red-tailed hawk
Arctic Peregrine Falcon
Falco peregrinus timdrius
Delisted
red-tailed hawk
Cactus Ferruginous Pygmy-Owl
Glaucidium brasilianum cactorum
Threatened
red-tailed hawk
Common Black-Hawk
Buteogallus anthracinus
Threatened
laughing gull
Gray Hawk
Asturina nitid/Buteo nitidus
Threatened
red-tailed hawk
Interior Least Tern
Sterna antillarum athalassos
Endangered
Endangered
belted kingfisher
Northern Aplomado Falcon
Falco femora/is septentrionalis
Endangered
Endangered
red-tailed hawk
Northern Beardless-Tyrannulet
Camptostoma imberbe
Threatened
American robin
Peregrine Falcon
Falco peregrinus
Delisted
Threatened
red-tailed hawk
Reddish Egret
Egretta rufescens
Threatened
great blue heron
Rose-throated Becard
Pachvramphus aglaiae
Threatened
American robin
Sprague's Pipit
Anthus spragueii
Candidate
for listing
American robin
Texas Botteri's Sparrow
Aimophila botterii texana
Threatened
American robin
Tropical Parula
Parula pitiayumi
Threatened
American robin
White-faced Ibis
Plegadis chihi
Threatened
laughing gull
White-tailed Hawk
Buteo albicaudatus
Threatened
red-tailed hawk
Wood Stork
Mycteria americana
Threatened
laughing gull
Zone-tailed Hawk
Buteo albonotatus
Threatened
red-tailed hawk
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
000754
Record of Decision
-------
Table 2
Threatened and Endangered Species that may be found in Hidalgo County
Common Name
Scientific Name
Federal
Status
State Status
Surrogate Species
Mammals
Coues' rice rat
Oryzomys couesi
Threatened
raccoon
Jaguar
Panthera onca
Endangered
Endangered
coyote
Jaguarundi
Herpailurus yaguarondi
Endangered
Endangered
coyote
Ocelot
Leopardus pardalis
Endangered
Endangered
coyote
Southern yellow bat
Lasiurus ega
Threatened
least shrew
White-nosed coati
Nasua narica
Threatened
least shrew
Reptiles
Black-striped snake
Coniophanes imperialis
Threatened
diamondback water snake
Northern cat-eyed snake
Leptodeira septentrionalis
septentrionalis
Threatened
diamondback water snake
Reticulate collared lizard
Crotaphytus reticulatus
Threatened
diamondback water snake
Speckled racer
Drymobius margaritiferus
Threatened
diamondback water snake
Texas horned lizard
Phrynosoma cornutum
Threatened
diamondback water snake
Texas indigo snake
Drymarchon melanurus erebennus
Threatened
diamondback water snake
Texas tortoise
Gopherus berlandieri
Threatened
diamondback water snake
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
000755
Record of Decision
-------
Table 2
Threatened and Endangered Species that may be found in Hidalgo County
Common Name
Scientific Name
Federal
Status
State Status
Surrogate Species
Amphibians
Black-spotted newt
Notophthalmus meridionalis
Threatened
American Bullfrog
Mexican Treefrog
Smilisca baudinii
Threatened
American Bullfrog
Sheep frog
Hypopachus variolosus
Threatened
American Bullfrog
South Texas siren (large form)
Siren sp 1
Threatened
American Bullfrog
White-lipped frog
Leptodactylus fragilis
Threatened
American Bullfrog
Plants
Star cactus
Astrophytum asterias
Endangered
Endangered
multiple species of
terrestrial plants
Texas ayenia
Ayenia limitaris
Endangered
Endangered
Walker's manioc
Manihot walkerae
Endangered
Endangered
Fish
Rio Grande silvery minnow
Hybognathus amarus
Endangered
Endangered
aquatic life criteria
protective of sensitive
species will be utilized
River goby
Awaous banana
Threatened
Mollusks
False spike mussel
Ouadrula mitchelli
Threatened
sediment quality criteria
protective of sensitive
species will be utilized
Salina mucket
Potamilus metnecktayi
Threatened
Texas hornshell
Popenaias popeii
Candidate
for listing
Threatened
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
000756
Record of Decision
-------
FIGURES
000757
-------
000758
-------
Main'Canal (MCr
i R i o'G rande'Riv ertRGRV
Alamo
Midway
North
Donna.
City of Donna
Water Treatment Plant
Midway
South
South Alamo
Weslaco]
Las Palomas Wildlife
Management Area -
Toarmina Unit
Las Palomas Wildlife
Managem ent Area -
Baird Unit
Tulsa
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
Oklahoma City
Albuquerque
Donna Irrigation District
Hidalgo County No. 1
Donna Reservoir
Lower East Main Canal
Arroyo Colorado River
Arroyo Colorado Tributary
Siphon (Underground)
Main Canal
Fort Worth Dallas
Upper West Main Canal
Cross Over Main Canal
Arlington
Figure 2
Site Layout
Austin
Lower West Main Canal Lined
Houston
Rio Grande River
San Antonio
Lower West Main Canal Unlined
Corpus Christi
Gulf
of
Mexico
McAllen
Feet L_
2,000 4,000
_l i I
(&)
000759
-------
Scale: 1™= 150'
Siphon Profile
Scale: 1" " 150' Hortz,; 1" = 15' Vert.
(10X Vertical Exaggeration)
45
Siphon Profile
45
Scale: 1" = 150' Vert. & Horiz.
(No Vertical Exaggeration)
Typical Siphon Section
Scale: 1* = 5'
Note:
This figure has been adopted from;
UR5 Corporation 200G, Feasibility Study Report,
Donna Reservoir and Canal System, Donna Hid alga
County. Texas Prepared for (ha Texas Commission on
Environmental Quality Jur«e
The siphon plan, profile, and sections shown on wis
drawing are based on historic siphon drawings from the
report Inverted Siphon Inspection by Remotely
Operated Vehicle (ASI Marino, 2001), and from
construction plans entitled Rehabilitation of Irrigation
Faculties - First Lift Main Canal prepared by Sigtar,
Clark & Associates. Westaco, Texas and oalod July
1961. The accuracy of the historic siphon drawings has
not been verified and all Information is approximate and
should not be used for design purposes.
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
Figure 3
Existing Siphon
Plan, Profile, and Sections
000760
-------
SEDIMENT
Human Health
mg/kg
Aroclor-1254
0.23
TCE3 2006,1/10 Non-Carcinogenic Rotective
Concentration Level for PCBs
Aroclor-1260
0.23
TCE3 2006,1/10 Non-Carcinogenic Rotective
Concentration Level for PCBs
Ecological
mg/kg
Aroclor-1254
0.06
TCEQ2014, Freshwater Ecological Benchmark
Aroclor-1260
0.005
TCEQ2014, Freshwater Ecological Benchmark
/ *****
j
I
1 — -
¦J
WB
1 Area
1 Enlarged
1 Above
, B
Legend
Arroyo Colorado River
Arroyo Colorado Tributary
Siphon (Underground)
Main Canal
Rio Grande River
Sample Locations by Matrix
O Sediment
Sample Identification
Sample Depth (if multiple depths): Aroclor-1254; Aroclor-1260 Results
500
_l
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
Figure 4
Concentrations of Aroclor-1254 and
Aroclor-1260 in Sediment in the Main Canal
and Rio Grande River
000761
-------
|Main\Canal TMC)1
Notes
1. Analyte concentrations are reported in milligram(s) per
kilogram.
2. Analyte concentrations shewn in green are below Human
Health and Ecological screening criteria.
3. All samples were collected between 0-6 inches below
ground surface, unless otherwise noted.
MC-118-SE (2014)
0-0.25 ft bgs: 0.00082 J
Abbreviations and Acronyms
bgs - Below ground surface
ft - Foot (feet)
mg/kg - Milligram(s) per kilogram
PCB - Polychlorinated biphenyl
TCEQ - Texas Commission on Environmental Quality
MC-102-SE (2012)
0.00053
Data Qualifier
J - Estimated Value. The analyte was positively identified
and the associated numerical value is approximate
concentration of the analyte in the sample.
MC-103-SE (2012)
0.00044
MC-106-SE (20121
0.5-1 ft bgs: 0.00063
MC-105-SE (20141
RGR-101-SE (20121
0.000021
MC-101-SE (20121
X 0.000057 J
toning Criteria
Total PCB Congeners
TCEQ 2014, Freshwater Ecological Benchmark for Total PCBs
Sample Identification
Sample Depth (if multiple depths): Total PCB Congener Results
Arroyo Colorado River
Arroyo Colorado Tributary
Siphon (Underground)
Main Canal
Rio Grande River
Sample Locations by Matrix
O Sediment
Figure 5
Concentrations of Total Polychlorinated
Biphenyl Congeners in Sediment in the
Main Canai and Rio Grande River
0-0.4 ft bgs: 0.0001 J
MC-117-SE (2014)
0-0.4 ft bgs: 0.0013
0.4-0.6 ft bgs: 0.00023 J
MC-114-SE (20141
Total PCB Congeners
TCEQ 2006, 1/10 Non-Carcinogenic Protective Concentration Level for PCBs
Ecological
000762
-------
[Canal Unlined (LWMCUyj
[Riv^(A'CR)1
AC R-120-S E (20131
0.0021 U 0.0021 U
Biological
Aroclcr-1254
Aroclcr-1260
ACR-119-SE (20131
.0021 U; 0.0021 U
ACR-113-SO (20121
0.0068 U; 0.0057 J
ACR-120-SQ (20131
.0021 U; 0.0021 U
ACR-1Q1-SQ (2Q14)
0.00097 U; 0.0012 J
ACR-118-SE (20131
0.0021 U; 0.0021 UJ
ACR-106-SE (20121
ACR- 110-SE (20121
ACR-102-SQ (20141
0.00096 U; 0.00096 U
ACR-108-SE (20121
| 0.071 U; 0.071 U
ACT-105-SE (20121
ACR-101 -SE (20121
0.056 U; 0.056 U
ACR-104-SE (20121
| 0.048 U; 0.048 U
ACR-117-SE (20131
10.00041 U; 0.00041 U
§@jl3BP5&
ACR-108-SQ (20121
0.04 U; 0.04 U
ACR-103-SE (20121
0.051 U; 0.051 U
ACR- 105-SQ (20121
0.066 U; 0.066 U
ACR-106-SQ (20121
0.036 U; 0.036 U
Human Health and Ecological Screening Criteria by Matrix
SEDIMENT
Human Health
TCE3 2006,1/10 Non-Carcinogenic Rotective Concentration Level for PCBs
TCE3 2006,1/10 Non-Carcinogenic Rotective Concentration Level for FCBs
Ecological
TCE32014, Freshwater Biological Benchmark
TCB3 2014, Freshwater Biological Benchmark
SOIL
Human Health
EPA 2015, Non-Carcinogenic Hazard Index of 0.1, Residential Screening Level
EPA 2015, Carcinogenic Target Risk 10-6, Residential Screening Level
TCBQ2014, Biological Benchmark for PCBs in Rants
TCBQ2014, Biological Benchmark for PCBs in Rants
Notes
1. Analyte concentrations are reported in milligram(s) per
kilogram.
2. Analyte concentrations shewn in green are below Human
Health and Ecological screening criteria.
3. All samples were collected between 0-6 inches below
ground surface, unless otherwise noted.
Abbreviations and Acronyms
- No data
EPA- U.S. Environmental Protection Agency
mg/kg - Milligram(s) per kilogram
TCEQ - Texas Commission on Environmental Quality
Data Qualifiers
J - Estimated Value. The analyte was positively identified
and the associated numerical value is approximate
concentration of the analyte in the sample.
U - Undetected. The analyte was analyzed for, but was not
detected at a level greater than or equal to the level of the
adjusted quantitation limit for the sample and method.
UJ - Undetected, Estimated Quantitation Limit. The analyte
was not detected at a level greater than or equal to the
adjusted quantitation limit. However, the reported adjusted
quantitation limit is approximate and may be inaccurate or
imprecise.
Legend
Lower West Main Canal Unlined Sample Locations by Matrix
Lower East Main Canal O Sediment
Arroyo Colorado River
Arroyo Colorado Tributary
¦¦¦ Siphon (Underground)
Main Canal
©
lent
O Soil
Sample Identification
Sample Depth (if multiple depths): Arocior-1254; Aroclor-1260 Results
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
Figure 6
Concentrations of Aroclor-1254 and
Aroclor-1260 in Sediment and Soil
in the Arroyo Colorado River and Tributary
000763
-------
(Canal LUnlined [(LWMCUfl
[Maih\Canal [(MCf
ACR-118-SE (2013^
0.00016
ACR-101-SQ (2012)
0-0.5 ft bgs: 0.0056
0.5-1 ft bgs: 0.0007
ACT-105-SE (2012)
ACR-101-SE (2012)
0.0016
ACR-102-SQ (2012)
0-0.5 ft bgs: 0.0019
0.5-1 ft bgs: 0.00068
ACR-104-SE (2012)
0.00036
Notes
1. Analyte concentrations are reported in milligram(s) per
kilogram.
2. Analyte concentrations shewn in green are below Human
Health and Ecological screening criteria.
3. All samples were collected between 0-6 inches below
ground surface, unless otherwise noted.
Abbreviations and Acronyms
bgs - Below ground surface
EPA-U.S. Environmental Protection Agency
ft - Foot (feet)
mg/kg - Milligram(s) per kilogram
PCB - Polychlorinated biphenyl
TCEQ - Texas Commission on Environmental Quality
IR-101-SO (2012)
0-0.5 ft bgs: 0.0038
0.5-1 ft bgs: 0.00029
ACR-120-SO (2013)
Human Health and Ecological Screening Criteria by Matrix
SEDIMENT
Total PCB Congeners
TCEQ 2006,1/10 Non-Carcinogenic Rotective Concentration Level for FCBs
Biological
Total FCB Congeners
TCEQ 2014, Freshwater Biological Benchmark for Total FCBs
SOIL
Biological
Total FCB Congeners
EPA 2015, Non-Carcinogenic Hazard Index of 0.1, Residential Screening Level for Aroclor-1254
Total FCB Congeners
TCEQ 2014, Biological Benchmark for Hants
Area
Enlarged
Above
Legend
Lower West Main Canal Unlined
Arroyo Colorado River
Arroyo Colorado Tributary
™ Siphon (Underground)
Main Canal
Sample Locations by Matrix
O Sediment
O So"'
©
Sample Identification
Sample Depth (if multiple depths): Total PCB Congener Results
Feet L
200
_l_
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
Figure 7
Concentrations of Total Polychlorinated
Biphenyl Congeners in Sediment and Soil
in the Arroyo Colorado River and Tributary
000764
-------
Human Health and Ecological Screening Criteria by Matrix
SBDIMBMT
Human Health
mg/kg
Aroclor-1254
0.23
TCE3 2006,1/10 Non-Carcinogenic Rotective
Concentration Level for FCBs
Aroclor-1260
0.23
TCE3 2006,1/10 Non-Carcinogenic Rotective
Concentration Level for FCBs
Ecological
mg/kg
Aroclor-1254
0.06
TCEQ2014, Freshwater Biological Benchmark
Aroclor-1260
0.005
TCEQ2014, Freshw ater Ecological Benchmark
SOIL
Human Health
mg/kg
Aroclor-1254
0.12
EPA 2015, Non-Carcinogenic Hazard Index of 0.1,
Residential Screening Level
Aroclor-1260
0.24
EPA 2015, Carcinogenic Target Risk 10-6, Residential
Screening Level
Ecological
mg/kg
Aroclor-1254
40
TCEQ2014, Biological Benchmark for FCBs in Hants
Aroclor-1260
40
TCEQ2014, Biological Benchmark for FCBs in Hants
Figure 8
Concentrations of Aroclor-1254 and
Aroclor-1260 in Sediment and Soil in the
Lower West Main Canal Unlined
South of 90 Degree Bend
000765
-------
Legend
Lower West Main Canal Unlined
Lower East Main Canal
Arroyo Colorado River
™ Siphon (Underground)
Sample Locations by Matrix
@ Sediment
O So"'
Samde Identification
Sample Depth (if multiple depths): Total PCB Congener Results (Exceedances in red)
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
Figure 9
Concentrations of Total Polychlorinated
Biphenyl Congeners in Sediment and Soil
in the Lower West Main Canal Unlined
South of 90 Degree Bend
0 100 200
Feet I I I I I
Area
I Enlarged
| Above
000766
-------
[Li nefl'(LWMCpfl
[U n I ireflttLW MC U)]
[Canal |(LiEMCf
[River;(ACRK
LWMCU-109-SE (2014)
0.0065 J; 0.0016 U
Aroclor-1260
TCEQ 2014, Biological Benchmark for PCBs in Hants
LWMCU-105-SE (20141
I 0.0094 J; 0.0017 U
LWMCU-117-SE (20131
0.0047 ; 0.0021 U
IR-104- SO (2012)
0.037 U; 0.037 U
LWMCU-151-SE (2013)
| 0.0055 ; 0.0021 U |
\f I LWMCU-108-SE (2014)
0.013 ; 0.0082 U
LWMCU-107-SE (20141
0.021 ; 0.0065 U
LWMCU-118-SE (2013)
0.0068 ; 0.0021 U j
LWMCU-11Q-SO (20141
0.0009 U; 0.0012 J
LVMV1CU-119-SE (2013)
0.0097; 0.0021 U
LWMCU-149-SE (20131
0.026 ; 0.0032 U
LWMCU-120-SE (2013)
0.0062 ; 0.0021 U
LWMCU-108-SO (20141
0.00092 U; 0.00092 U
LWMCU-153-SE (20131
0.012 J; 0.0032 U
LWMCU-106-SE (20141
0.078 J; 0.012 U
LWMCU-104-SE (20141
LWMCU-109-SQ (20141
30091 UJ; 0.00091 UJ
LWMCU-121-SE (20131
LWMCU-122-SE (20131
0.011 ; 0.0021 U
LWMCU-103-SE (2014)
0.058 ; 0.015 U
Notes
1. Analyte concentrations are reported in milligram(s) per
kilogram.
2. Analyte concentrations shewn in green are below Human
Health and Ecological screening criteria.
3. Analyte concentrations shown in red are equal to or
exceed Human Health and/or Ecological screening criteria.
4. All samples were collected between 0-6 inches below
ground surface, unless otherwise noted.
Abbreviations and Acronyms
No data
EPA-U.S. Environmental Protection Agency
mg/kg - Milligram(s) per kilogram
TCEQ - Texas Commission on Environmental Quality
Data Qualifiers
- Estimated Value. The analyte was positively identified
and the associated numerical value is approximate
concentration of the analyte in the sample.
U - Undetected. The analyte was analyzed for, but was not
detected at a level greater than or equal to the level of the
adjusted quantitation limit for the sample and method.
UJ - Undetected, Estimated Quantitation Limit. The analyte
was not detected at a level greater than or equal to the
adjusted quantitation limit. However, the reported adjusted
quantitation limit is approximate and may be inaccurate or
imprecise.
I I I ¦ ¦ M I. II « l>
SEDIMENT
SOIL
Human Health
Aroclor-1254
TCE3 2006,1/10 Non-Carcinogenic Rotective Concentration Level for FCBs
Aroclor-1260
Biological
Aroclor-1254
Aroclor-1260
TCB32014, Freshwater Biological Benchmark
Human Health
Aroclor-1254
EPA 2015, Non-Carcinogenic Hazard hdex of 0.1, Residential Screening Level
Aroclor-1260
EPA 2015, Carcinogenic Target Risk 10-6, Residential Screening Level
Biological
Aroclor-1254
TCEQ 2006,1/10 Non-Carcinogenic Rotective Concentration Level for PCBs
TCEQ 2014, Freshwater Biological Benchmark
TCEQ 2014, Biological Benchmark for PCBs in Rants
Legend
¦n™ Lower West Main Canal Lined
Lower West Main Canal Unlined
Lower East Main Canal
Arroyo Colorado River
Sample Locations by Matrix
O Sediment
Soil
Sample Identification
Sample Depth (if multiple depths): Aroclor-1254; Aroclor-1260 Results (Exceedances in red)
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
Figure 10
Concentrations of Aroclor-1254 and
Aroclor-1260 in Sediment and Soil in the
Lower West Main Canal Unlined
North of 90 Degree Bend
000767
-------
Lined (LWMCL)
Human Health and Ecological Screening Criteria by Matrix
SEDIMENT
Human Health
mg/kg
Total FCB Congeners
0.23
TCEQ 2006,1/10 Non-Carcinogenic Rotective Concentration Level for FCBs
Ecological
mg/kg
Total FCB Congeners
0.0598
TCEQ 2014, Freshwater Ecological Benchmark fa Total FCBs
SOIL
Human Health
mg/kg
Total FCB Congeners
0.12
EPA 2015, Non-Carcinogenic Hazard Index of 0.1, Residential Screening Level for Aroclor-1254
Ecological
mg/kg
Total FCB Congeners
40
TCEQ 2014, Ecological Benchmark for Hants
Figure 11
Concentrations of Total Polychlorinated
Biphenyl Congeners in Sediment and Soil
in the Lower West Main Canal Unlined
North of 90 Degree Bend
000768
-------
Unlined (LWMCU)'.
[River|(ACR)'
LEMC-106-SE (20141
0.022 J; 0.0093 UJ
LEMC-105-SE (2014)
0.018 J; 0.0076 UJ
LEMC-102-SE (2014)
023 J; 0.0089 UJ
LEMC-107-SE (20121
0.0017 J; 0.0053 U
LEMC-104-SE (20121
0.0012 J; 0.0052 U
LEMC-108-SE (20121
0.0022 J; 0.004 U
IR-105-SQ (20121
36 U; 0.036 U
LEMC-103-SE (20141
;
IR-103-SQ (2012)
0.036 U; 0.036 U
LEMC-101-SE (20121
0.0043 U; 0.0043 U
Notes
1. Analyte concentrations are reported in milligram(s) per
kilogram.
2. Analyte concentrations shown in green are below Human
Health and Ecological screening criteria.
3. All samples were collected between 0-6 inches below
ground surface, unless otherwise noted.
Abbreviations and Acronyms
EPA- U.S. Environmental Protection Agency
mg/kg - Milligram(s) per kilogram
TCEQ- Texas Commission on Environmental Quality
Data Qualifiers
J - Estimated Value. The analyte was positively identified
and the associated numerical value is approximate
concentration of the analyte in the sample.
U - Undetected. The analyte was analyzed for, but was not
detected at a level greater than or equal to the level of the
adjusted quantitation limit for the sample and method.
UJ - Undetected, Estimated Quantitation Limit. The analyte
was not detected at a level greater than or equal to the
adjusted quantitation limit. However, the reported adjusted
quantitation limit is approximate and may be inaccurate or
imprecise.
Human Health and Ecological Screening Criteria by Matrix
TCEQ 2006, 1/10 Non-Carcinogenic Protective Concentration Level for FCBs
TCEQ 2006, 1/10 Non-Carcinogenic Rotective Concentration Level for FCBs
Biological
TCEQ2014, Freshwater Biological Benchmark
TCEQ 2014, Freshw ater Biological Benchmark
SOIL
EPA 2015, Non-Carcinogenic Hazard Index of 0.1, Residential Screening Level
EPA 2015, Carcinogenic Target Risk 10-6, Residential Screening Level
Biological
TCEQ 2014, Biological Benchmark for FCBs in Rants
TCEQ 2014, Biological Benchmark for FCBs in Rants
Aroclor-1260
Legend
Lower West Main Canal Unlined
Lower East Main Canal
Arroyo Colorado River
Sample Locations by Matrix
O Sediment
^ Soil
Sample Identification
Sample Depth (if multiple depths): Aroclor-1254; Aroclor-1260 Results
0 500 1,000
Feet I I I I I
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
Figure 12
Concentrations of Aroclor-1254 and
Aroclor-1260 in Sediment and Soil
in the Lower East Main Canal
mi
000769
-------
Human Health and Ecological Screening Criteria by Matrix
SEDIMENT
Human Health
mg/kg
Total FCB Congeners
0.23
TCEQ 2006,1/10 Non-Carcinogenic Rotective Concentration Level for FCBs
Biological
mg/kg
Total FCB Congeners
0.0598
TCEQ 2014, Freshwater Biological Benchmark for Total FCBs
SOIL
Human Health
mg/kg
Total FCB Congeners
0.12
B^A 2015, Non-Carcinogenic Hazard Index of 0.1, Residential Screening Level for Aroclor-1254
Biological
mg/kg
Total FCB Congeners
40
TCEQ 2014, Biological Benchmark for Hants
Notes
1. Analyte concentrations are reported in milligram(s) per
kilogram.
2. Analyte concentrations shown in green are below Human
Health and Ecological screening criteria.
3. All samples were collected between 0-6 inches below
ground surface, unless otherwise noted.
Abbreviations and Acronyms
bgs - Below ground surface
EPA- U.S. Environmental Protection Agency
ft - Foot (feet)
mg/kg - Milligram(s) per kilogram
PCB - Polychlorinated biphenyl
TCEQ - Texas Commission on Environmental Quality
Figure 13
Concentrations of Total Polychlorinated
Biphenyl Congeners in Sediment and Soil
in the Lower East Main Canal
000770
-------
Canal (C'OMC)
RN3W-101-SE (20141
0.0021 J; 0.002 U
RN3E-1Q1-SE (20141
0.0011 UJ; 0.0017 J
RN3E-102-SE (20121
0.013 U; 0.013 U
RN3E-103-SE (20121
0.014 U; 0.014 U
RN3E-105-SE (20121
0.0093 U; 0.0093 U
RN3E-104-SE (20121
0.012 U; 0.0028 J
RN3W-108-SE (20121
Human Health and Ecological Screening Criteria by Matrix
TCEQ 2014, Freshwater Biological Benchmark
ThirdlEnlargement
'ReservoiriRN3E)
ReservoirI(RN3W)
RN3W-102-S E (201411
0.0016 UJ; 0.0016 U |
0.0029 J; 0.0018 U
RN3W-106-SE (20121
0.0051 U; 0.0051 U
RN3W-105-SE (20141
0.0027 J; 0.0018 UJ
RN3W-107-SE (20121
0.0049 U; 0.0049 U
0.0032 U; 0.0032 U
TCEQ 2006,1/10 Non-Carcinogenic Rotective Concentration Level for PCBs
TCEQ 2006,1/10 Non-Carcinogenic Rotective Concentration Level for PCBs
TCEQ 2014, Freshwater Biological Benchmark
SEDIMENT
Human Health
Aroclor-1260
Biological
Aroclor-1254
Aroclor-1260
Aroclor-1254
Notes
1. Analyte concentrations are reported in milligram(s) per
kilogram.
2. Analyte concentrations shown in green are below Human
Health and Ecological screening criteria.
3. All samples were collected between 0-6 inches below
ground surface, unless otherwise noted.
Abbreviations and Acronyms
mg/kg- Milligram(s) per kilogram
TCEQ - Texas Commission on Environmental Quality
Data Qualifiers
J - Estimated Value. The analyte was positively identified
and the associated numerical value is approximate
concentration of the analyte in the sample.
U - Undetected. The analyte was analyzed for, but was not
detected at a level greater than or equal to the level of the
adjusted quantitation limit for the sample and method.
UJ - Undetected, Estimated Quantitation Limit. The analyte
was not detected at a level greater than or equal to the
adjusted quantitation limit. However, the reported adjusted
quantitation limit is approximate and may be inaccurate or
imprecise.
Area
'Enlarged
Above
Legend
Cross Over Main Canal
Lower West Main Canal Lined
Sample Locations by Matrix
O Sediment
©
Sample Identification
Sample Depth (if multiple depths): Aroclor-1254; Aroclor-1260 Results
Feet L
400
_l
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
Figure 14
Concentrations of Aroclor-1254 and
Aroclor-1260 in Sediment in Reservoir No. 3
t&i
000771
-------
Canal (C'OMC)
RN3W-1Q1-SE (2012)
0-0.5 ft bgs: 0.0085
0.5-1 ft bgs: 0.0043
RN3E-101-SE (2012)
0.0037
Total PCB Congeners
Ecological
Total PCB Congeners
ThirdlEnlargement
'ReservoiriRN3E)
ReservoirI(RN3W)
RN3W-102-SE (2012)
0.01 I
RN3W-105-SE (2014)
TCEQ 2006, 1/10 Non-Carcinogenic Rotective Concentration Level for PCBs
TCEQ2014, Freshwater Ecological Benchmark for Total PCBs
Abbreviations and Acronyms
bgs - Below ground surface
ft - Foot (feet)
mg/kg - Milligram(s) per kilogram
PCB - Polychlorinated biphenyl
TCEQ - Texas Commission on Environmental Quality
Data Qualifier
J - Estimated Value. The analyte was positively identified
and the associated numerical value is approximate
concentration of the analyte in the sample.
Human Health and Ecological Screening Criteria by Matrix
Notes
1. Analyte concentrations are reported in milligram(s) per
kilogram.
2. Analyte concentrations shewn in green are below Human
Health and Ecological screening criteria.
3. All samples were collected between 0-6 inches below
ground surface, unless otherwise noted.
Area
'Enlarged
Above
Legend
Cross Over Main Canal
Lower West Main Canal Lined
Sample Locations by Matrix
O Sediment
©
Sample Identification
Sample Depth (if multiple depths): Total PCB Congener Results
400
_l
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
Figure 15
Concentrations of Total Polychlorinated
Biphenyl Congeners in Sediment in
Reservoir No. 3
000772
-------
Aroclor-1260
City of Donna Water Treatment
Plant Sediment Sample
CQMC-106-SE (20121
0.0066 U; 0.0066 U
CQMC-107-SE (20121
0.0061 U; 0.0061 U
CQMC-104-SE (20141
0.0013 U; 0.0013 U
CQMC-103-SE (20141
0.0082 J; 0.0012 U
CQMC-1Q5-SE (2014)
0.0016 U; 0.0016 U
CQMC-108-SE (20121
0.0077 U; 0.0077 U
COMC-1Q1-SE (20141
0.0021 J; 0.001 J
CQMC-1P9-SE (2014)
0.0023 J; 0.0013 U
Area
'Enlarged
Above
Data Qualifiers
J - Estimated Value. The analyte was positively identified
and the associated numerical value is approximate
concentration of the analyte in the sample.
- Undetected. The analyte was analyzed for, but was not
ietected at a level greater than or equal to the level of the
adjusted quantitation limit for the sample and method.
Sample Identification
Sample Depth (if multiple depths): Aroclor-1254;Aroclor-1260 Results
Human Health and Ecolo«
al Screening Criteria by Matrix
Human Health
Aroclor-1254
Aroclor-1260
Biological
Aroclor-1254
Abbreviations and Acronyms
mg/kg - Milligram(s) per kilogram
TCEQ- Texas Commission on Environmental Quality
Figure 16
Concentrations of Aroclor-1254 and
Aroclor-1260 in Sediment in the Cross Over
Main Canal and Water Treatment Plant
Legend
Cross Over Main Canal
Lower West Main Canal Lined
Sample Locations by Matrix
© Sediment
Notes
1. Analyte concentrations are reported in milligram(s) per
kilogram.
2. Analyte concentrations shown in green are below Human
Health and Ecological screening criteria.
3. All samples were collected between 0-6 inches below
ground surface, unless otherwise noted.
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
TCEQ 2006,1/10 Non-Carcinogenic Rotective Concentration Level for FCBs
TCEQ 2006,1/10 Non-Carcinogenic Rotective Concentration Level for FCBs
TCEQ2014, Freshwater Biological Benchmark
TCEQ 2014, Freshwater Biological Benchmark
City of Donna Water Treatment
Plant Sediment Sample
DWP-101-SE (20121
0.075 U; 0.075 U ,
CQMC-101-SE (20121
0.0052 U; 0.0052 U
000773
-------
Human Health and Ecological Screening Criteria by Matrix
[Human Health
[Total RGB Congeners
TCEQ 2006,1/10 Non-Carcinogenic Protective Concentration Level for PCBs
(Ecological
ITotal FCB Congeners
TCEQ 2014, Freshwater Ecological Benchmark for Total PCBs
City of Donna Water Treatment
Plant Sediment Sample
DWP-101-SE (20121
COMC-1Q1-SE (20121
Notes
1. Analyte concentrations are reported in milligram(s) per
kilogram.
2. Analyte concentrations shown in green are below Humai
Health and Ecological screening criteria.
3. All samples were collected between 0-6 inches below
ground surface, unless otherwise noted.
Abbreviations and Acronyms
mg/kg - Milligram(s) per kilogram
PCB - Polychlorinated biphenyl
TCEQ - Texas Commission on Environmental Quality
Data Qualifier
J - Estimated Value. The analyte was positively identified
and the associated numerical value is approximate
concentration of the analyte in the sample.
Legend
Cross Over Main Canal
Lower West Main Canal Lined
Sample Locations by Matrix
© Sediment
Sample Identification
Sample Depth (if multiple depths): Total PCB Congener Results
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
Figure 17
Concentrations of Total Polychlorinated
Biphenyl Congeners in Sediment in the
Cross Over Main Canal and Water
Treatment Plant
000774
-------
fcarial (COMC)
irtf EnlafgAefhent]^ j
) [R e s'e rv oi rl( R N ZEy
Aroclor-1254
Concentration
(mg/kg)
Aroclor-1260
Concentration
(mg/kg)
ROB
Concentration
(mg/kg)
Sample ID
DRM-173-F
DRM-174-F
DRM-175-F
DRM-184-F
LMB-176-F
WHB-177-F
LMB-112-F
LMB-112-W
Aroclor-1254
Concentration
(mg/kgj
Aroclor-1260
Concentration
(mg/kg)
FCB
Concentration
(mg/kg)
Sample ID
BUF-166-F
BUF-170-F
DRM-167-F
LMB-163-F
LMB-171-F
LMB-172-F
WHB-164-F
Aroclor-1254
Concentration
(mg/kg)
Aroclcr-1260
Concentration
(mg/kg)
Sample ID
BUF-133-F
BUF-138-F
LMB-132-F
LMB-137-F
LMB-141-F
LMB-142-F
SHD-135-F
Aroclor-1254
Concentration
(mg/kg)
Sample ID
LMB-121-F
LMB-122-F
LMB-123-F
LMB-101-F
LMB-124-F
LMB-101-W
LMB-125-F
rArr6yo Colorado
River (ACR)
1
FCB
Concentration
I (mg/kg)
2012 Area 1
Sample ID
Aroclor-1254
Concentration
(mg/kg)
4.5 J
Aroclor-1260
Concentration
(mg/kg)
3.6 J
2013 Area 1
Note
An asterisk denotes a duplicate sample.
Sample IDs with "-F" indicate fish fillets.
Sample IDs with "-W indicate whole body samples.
Abbreviations and Acronyms
No data
mg/kg - Milligram(s) per kilogram
PCB - Polychlorinated biphenyl
Data Qualifiers
J - Estimated Value. The analyte was positively
identified and the associated numerical value is
approximate concentration of the analyte in the
sample.
U - Undetected. The analyte was analyzed for,
but was not detected at a level greater than or
equal to the level of the adjusted quantitation limit
for the sample and method.
Aroclor-1260
Concentration
(mg/kg)
PCB
Concentration
(mg/kg)
CAT-147-F
GAR-146-F
0.21 J
0.14 J
LMB-144-F
LMB-145-F
WHB-148-F
Sample ID
Aroclcr-1254
Concentration
(mg/kg)
Aroclcr-1260
Concentration
(mg/kg)
PCB
Concentration
(mg/kg)
CAR-115-F*
CAT-116-W
Sample ID
Aroclcr-1254
Concentration
(mg/kg)
Aroclor-1260
Concentration
(mg/kg)
FCB
Concentration
(mg/kg)
CAR-111-W
2015
Area 4
Sample ID
Aroclor-1254
Concentration
(mg/kg)
Aroclor-1260
Concentration
(mg/kg)
PCB
Concentration
(mg/kg)
CAT-156-F
GAR-149-F
GAR-151-F
LMB-155-F
WHB-157-F
0.0041 U
0.12 J
0.059
Scissors
2015
Aroclor-1254
Concentration
(mg/kg)
0.073 J
0.033 U
0.033 U
Area 1
Aroclor-1260
Concentration
(mg/kg)
0.033 U
0.033 U
0.033 U
PCB
Concentration
(mg/kg)
0.016 J
0.005
0.014 J
2015
Area2
LMB-128-F
0.015
0.0097
0.015
Sample ID
CAR-119-F
CAR-127-F
GAT-117-F
Albuquerque OkLahoma City «
• I 9
OK A R
TX
Fort Worth Da Lias
ArLington .LA
Austin
San Antonio
•
Corpus Christi
McALLen,,
Mexico
Hp
Gulf
of
Mexico
Legend
Cross Over Main Canal
Lower West Main Canal Lined
' Main Canal
I Rio Grande River
Lower West Main Canal Unlined Donna Reservoir
' Lower East Main Canal
1 Arroyo Colorado River
Arroyo Colorado Tributary
Siphon (Underground)
~ Donna Irrigation District -
Hidalgo County No. 1
(I I ] 2012 Fish Sample Area
[l l] 2013 Fish Sample Area
[ m\ 2015 Fish Sample Area
Feet L
2,000
i
©
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
Figure 18
Fish Concentrations of Aroclor-1254,
Aroclor-1260, and Total Polychlorinated
Biphenyl Congeners
000775
-------
-Existing Intake Headwall
-9' Inside Diameter Concrete Siphon
Siphon Plan View
Scale: 1*= 150"
pg/L - picagrams per liter
Sample locstfon? should be considered approximate.
Row measured at the Rio Grande Pumping station was
40 cubic feet per second (cfs)
-------
Figure 20
Semi-Permeable Membrane Device
Concentrations of Total Polychlorinated
Biphenyl Congeners
000777
-------
MC-127-SE-0-6
Lwrtlpn Q1
(LWMCU-173-POM-S)
(LWMCU-174-POM-W)
(LWMCU-187-SE-0-6)
Loqttlpn 9?
{LWMCU-177-POM-S)
(LWMCU-178-POM-W)
(LWMCU-189-SE-0-6)
Lotion 9$
(LWMCU-181-POM-S)
(LWMCU-182-POM-W)
(LWMCU-191-SE-Q-6)
(LWMCU-179-POM-S)
(LWMCU-180-POM-W)
(LWMCU-190-SE-0-6)
QS&aiXgEi)
Location 07
(MC-126-SE-0-6)
(MC-127-SE-0-6)
Sum of Detectable PCBCongeners (ng/g)
262.05
167.94
2.91 E-Q4
1.49E-Q4
Bulk Sediment
Surface Water
25 Mm CP0H
Sediment
Pore Water
25 pm Cp^
Surface Water
25 |jm Ctee
Sediment
Pore Water
25 |jm Cfee
75.07
324.77
4.Q9E-Q4
2.95 E-04
LWMCU-180-POM-W
LWMCU-179-POM-S
LWMCU-190-SE-0-6
Sample Identification
157.26
Note:
1 field duplicate sample
— - data unavailable, passive sarrplers stolen prior to retrieval from the field
|jm- nicrometer
ng/g - nanogram per gram
Cfree - Freely dissolved concentration
PCB - Ftoiychlorinated biphenyl
POM - Ftolyoxymethylene
Location 02
ft. I (LWMCU-175-POM-S) I
(LWMCU-176-POM-W)
| (LWMCU-188-SE-0-6)
Legend
Lower West Main Canal Unlined
Lower East Main Canal
Arroyo Colorado River
Arroyo Colorado Tributary
™ Siphon (Underground)
Main Canal
Sample Locations by Matrix
^ Polyoxymethylene
O Sediment
Location
(Sample Identification)
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
Figure 21
Polyoxymethylene Concentrations of
Total Polychlorinated Biphenyl Congeners
000778
-------
FIGURE 22 HUMAN HEALTH CONCEPTUAL SITE MODEL, DONNA RESERVOIR AND CANAL SYSTEM
PRIMARY
SOURCE
PRIMARY
RELEASE
MECHANISM
SECONDARY
SOURCE
SECONDARY
RELEASE
MECHANISM
TERTIARY
SOURCE
TERTIARY
RELEASE
MECHANISM
QUATERNARY
SOURCE
EXPOSURE
ROUTE
POTENTIAL RECEPTORS
Industrial
Worker
Construction /
Agricultural
Worker
Recreational/
Trespasser
Resident
Ingestion
C
C
C
C
Dermal Contact
C
C
C
C
Unknown Source
Material
Spills and Leaks
Surface
Soil
Surface
Water (1)
Subsurface
Soil
Wind Suspension
Wind Suspension
Volatilization
Infiltration and
Percolation
Root Uptake
Agricultural Produce
J
L
Bioaccumulation
Domestic
Livestock
x
Inhalation |
I
I
Outdoor Air
(VOCs)
H Inhalation I I I I I
Desorption
Surface Water
Ingestion
C
C
C
C
Dermal Contact
C
C
C
C
Wind Suspension
Desorption
Surface
Water
r
Uptake/
Fish
Bioaccumulation
(Fillet)
Dermal Contact
Wind Suspension
Inhalation |"
Outdoor Air
(VOCs)
*1 Inhalation T
I
Incomplete or negligible exposure pathway
Volatilization
Construction Trench
C
Potentially complete exposure pathway
(Construction)
Air (VOCs)
P
(1)
Potentially complete exposure pathway. Polychlorinated biphenyls do not typically migrate to
groundwater or accumulate in vegetation.
Possible sources of contamination could include herbicides, pesticides, or other contaminants
(e.g., polychlorinated biphenyls) from the Rio Grande River or Arroyo Colorado
Volatilization
Indoor Air
(Domestic Use)
(VOCs)
Ingestion
C
C
C
C
Dermal Contact
C
C
C
C
Ingestion
C
C
C
C
Dermal Contact
C
C
C
C
Sorption
Sediment
Ingestion
C
C
C
C
Dermal Contact
C
C
C
C
Ingestion
C
C
C
C
Dermal Contact
C
C
C
C
Ingestion
P
P
I
P
Dermal Contact
P
P
I
P
000779
-------
Third Enlargement
. ->k
Midway V41
• ".North \
i Donna' '
Midway,
South
BPPifl
¦SoutnrAlanhd
Exposure Area 5: Lined Canals, Reservoirs, and Soil
COMC, R3NE, R3NW, LWMCL, LEMC
Weslaco
LWMCU
Exposure Area 2: Arroyo Colorado
ACR, ACT
Exposure Area 3: LWMCU at the Siphon Exit
SIP, LWMCU
Exposure Area 1: Upstream of the Siphon
Exposure Area 4: LWMCU Downstream of the Siphon
ALbuquerqu© Oklahoma City
OK AR
Fort Worth Da Lias
GEP
Arlington
Austin
San Antonio
Corpus Christi
McALLen-
Mexico
Gulf
Mexico
~ Donna Irrigation District -
Hidalgo County No. 1
Donna Reservoir
| Exposure Area 1: Upstream of the Siphon
~ Exposure Area 2: Arroyo Colorado
| Exposure Area 3: LWMCU at the Siphon Exit
| Exposure Area 4: LWMCU Downstream of the Siphon
~ Exposure Area 5: Lined Canals, Reservoirs, and Soil
Figure 23
Ecological Exposure Areas
2,000 4,000
_i i i i
000780
-------
PRIMARY
SOURCES
SECONDARY
SOURCES
EXPOSURE
MEDIA
EXPOSURE
PATHWAYS
RECEPTORS
UNDETERMINED
LANDSIDE SOURCES
Possible illegal dumping,
herbicide, pesticide, and/or
dust control sprays.
\\
\
DONNA CANAL
SlDTMKMTg
Historically deposited
sediments
Arroyo Colorado
(Sediment and
surface water)
ARROYO COLORADO
SEDIMENTS
Historically deposited
sediments
RIO GRANDE
SEDIMENTS
Historically deposited
DONNA RESERVOIR
SEDIMENTS
Historically deposited
UNDETERMINED
LANDSIDE SOURCES
Possible illegal dumping,
herbicide, pesticide, and/or
dust control sprays.
DREDGED MATERIAL
Sediments dredged from
Donna Canal and placed
along the canal banks
Donna Canal
(Sediment and
surface water)
Donna Reservoir
(Sediment and
surface water)
Secondary Ditches
(Sediment and surface
water during brief wet
periods)
Plants
Aquatic and
benthic
organisms
Animals
Birds
Mammals
Reptiles &
Amphibians
Surface water
Ingestion
NA
O
Direct/dermal Contact*
o
o
O
Sediment
Ingestion
Direct/dermal Contact*
o
o
o
Aquatic food chain
Ingestion of plants/prey that
have accumulated chemicals
NA
•
•
•
•
Plants
Soil
Invertebrates
Animals
Birds
Mammals
Reptiles &
Amphibians
Airborne dust
Inhalation*
NA
NA
o
o
O
Direct/dermal Contact*
O
O
o
o
o
Soil
Ingestion
NA
9
Direct/dermal Contact*
9
o
o
o
Terrestrial food chain
Ingestion of plants/prey that
have accumulated chemicals
NA
o
•
•
•
* Inhalation, direct contact, and surface water ingestion are identified as complete pathways for
higher trophic level wildlife. However, example calculations and information provided in EPA
and other exposure modeling guidance demonstrates that these pathways are insignificant
compared to ingestion (EPA, 2003; USACHPPM, 2004).
O
CZ5
NA
Complete pathway
Complete pathway, but not significant
Incomplete pathway
Not applicable
Clearly defined fate, transport, or
exposure relationship
Uncertain fate, transport, or exposure
relationship
FIGURE 24 ECOLOGICAL CONCEPTUAL SITE MODEL, DONNA RESERVOIR AND CANAL SYSTEM
000781
-------
•». ••••::•• 7
* « -9k.
.¦L«
jlSt
Area
Enlarged
at Right
Areas
Enlarged
Above
Legend
Cross Over Main Canal
Lower West Main Canal Lined
Lower West Main Canal Unlined
Lower East Main Canal
Arroyo Colorado River
Arroyo Colorado Tributary
¦¦¦ Siphon (Underground)
Main Canal
Rio Grande River
[__| Remediation Area
Arocior-1254, Aroclor-1260, or Total
PCB Congener Concentrations in Sediment
Does not Exceed Cleanup Goal
° <0.043 mg/kg
— Exceeds Cleanup Goal
® >0.043mg/kg
mg/kg - Milligram(s) per kilogram
PCB - Polychlorinated Biphenyl
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
Figure 25
Sediment Remediation Area Based on a
Sediment Cleanup Goal of 0.043 mg/kg
000782
-------
000783
-------
Biomagnification
(big fish eats little fish)
Higher Trophic Fish
Bioaccumulation
(PCBs enter organisms
from sediment and surface water)
Deposition
Adsorption,
Desorption
.C->
Lower Trophic Fish
. - p0g Qontamifiated Sediment
>ifL
,WWi
3 C> o °
Remedial Investigation/Feasibility Study
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
Figure 27
Pictorial Conceptual Site Model
Surface Water Flow
Polychlorinated Biphenyi (PCB) Transport
Particles with PCBs Attached
000784
-------
Appendix A
Summary of Human Health Exposure Factors and Intake Equations
000785
-------
VALUES USED FOR RESIDENT ADULT DAILY SOIL INTAKE EQUATIONS
Scenario Timeframe: Current/Future
Medium: Soil
Exposure Medium: Soil, Air
Exposure Point: Donna Reservoir and Canal System
Receptor Population: Resident
Receptor Age: Adult
Exposure
Parameter
Parameter Definition
Units
RME Value
RME
Intake Equation / Model Name
Route
Code
Rationale/Reference
Ingestion
CS
Chemical Concentration in Soil
mg/kg
Chemical-Specific
Chemical-Specific
Chronic Daily Intake (CDI) (mg/kg/day) =
CR
Ingestion Rate
mg/day
100
U.S. EPA 2011
CS x CR x EF x ED x CF / (BW x AT)
EF
Exposure Frequency
day/yr
350
U.S. EPA 1991a
ED-NC
Exposure Duration - Noncancer
F
20
U.S. EPA 2011
ED-C
Exposure Duration-Cancer
F
20
U.S. EPA 2011
BW
Body Weight
kg
80
U.S. EPA 2011
Mutagenic Chronic Daily Intake (MCDI) (mg/kg/day) =
AT-NC
Averaging time - Noncancer
days
7,300
U.S. EPA 1989
CS x EF x ([(ED6.16 x CR x 3) + (ED,6.30 x CR x 1)]/BW) x CF / (AT)
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
CF
Conversion Factor
kg/mg
1.0E-06
U.S. EPA 1989
Dermal
CS
Chemical Concentration in Soil
mg/kg
Chemical-Specific
Chemical-Specific
CDI (mg/kg/day) =
SA
Surface Area for Contact
cm2/event
6,032
U.S. EPA 2015a
CS x SA x AF x ABS x EF x ED x CF / (BW x AT)
AF
Adherence Factor
mg/cm2
0.07
U.S. EPA 2004 (1)
EF
Exposure Frequency
event/yr
350
U.S. EPA 1991a
ED-NC
Exposure Duration - Noncancer
yr
20
U.S. EPA 2011
ED-C
Exposure Duration - Cancer
yr
20
U.S. EPA 2011
Mutagenic Chronic Daily Intake (MCDI) (mg/kg/day) =
BW
Body Weight
kg
80
U.S. EPA 2011
CS x EF x ABS x ([(ED6.,6 x SA x AF x 3) + (ED,6.30 x SA x AF x 1)]/BW) x CF / (AT)
AT-NC
Averaging time - Noncancer
days
7,300
U.S. EPA 1989
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
CF
Conversion Factor
kg/mg
1.0E-06
U.S. EPA 1989
ABS
Dermal Absorption Fraction
unitless
Chemical-Specific
U.S. EPA 2004 (2)
Inhalation
CA
Chemical Concentration in Air
mg/m3
Chemical-Specific
Chemical-Specific
Exposure Concentration (ng/m3 or mg/m3) =
CF,
Conversion Factor
(xg/mg
1,000
U.S. EPA 2009a
CA x CF, x ET x EF x ED / AT x CF2
ET
Exposure Time
hr/day
24
U.S. EPA 2009a
Note: CF, only used in carcinogenic intake calculations
EF
Exposure Frequency
day/yr
350
U.S. EPA 1991a
ED-NC
Exposure Duration - Noncancer
yr
20
U.S. EPA 2011
ED-C
Exposure Duration - Cancer
yr
20
U.S. EPA 2011
Mutagenic Exposure Concentration (MEC) (jig/m3) =
AT-NC
Averaging time - Noncancer
days
7,300
U.S. EPA 1989
CA x ET x EF x [(ED6.,6 x 3) + (ED,6.30 x 1)] x CF, / (AT x CF2)
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
cf2
Conversion Factor
hr/day
24
U.S. EPA 2009a
(1) Taken from Exhibit 3-5 of USEPA 2004.
(2) Taken from Exhibit 3-4 of USEPA 2004.
BPJ = Best Professional Judgment
U.S. EPA = United States Environmental Protection Agency
CDI = chronic daily intake
mg/kg = milligrams per kilogram
kg/mg = kilograms per milligram
mg/cm = milligrams per square centimeter
mg/day = milligrams per day
day/yr = days per year
RME = Reasonable Maximum Exposure
mg/m3 = milligram per cubic meter
|ig/m = micrograms per cubic meter
cm2 /event = square centimeters per event
Hg/mg = microgram per milligram
kg = kilogram
hr/day = hours per day
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
Record of Decision
000786
-------
VALUES USED FOR RESIDENT CHILD DAILY SOIL INTAKE EQUATIONS
Scenario Timeframe: Current/Future
Medium: Soil
Exposure Medium: Soil, Air
Exposure Point: Donna Reservoir and Canal System
Receptor Population: Resident
Receptor Age: Child
Exposure
Route
Parameter
Code
Parameter Definition
Units
RME Value
RME
Rationale/Reference
Intake Equation / Model Name
Ingestion
CS
Chemical Concentration in Soil
mg/kg
Chemical-Specific
Chemical-Specific
Chronic Daily Intake (CDI) (mg/kg/day) =
CR
Ingestion Rate
mg/day
200
U.S. EPA 2011
CS x CR x EF x ED x CF / (BW x AT)
EF
Exposure Frequency
day/yr
350
U.S. EPA 1991a
ED-NC
Exposure Duration - Noncancer
y
6
U.S. EPA 1991a
ED-C
Exposure Duration-Cancer
y
6
U.S. EPA 1991a
BW
Body Weight
kg
15
U.S. EPA 1989
Mutagenic Chronic Daily Intake (MCDI) (mg/kg/day) =
AT-NC
Averaging time - Noncancer
days
2,190
U.S. EPA 1989
CS x EF x ([(ED0_2 x CR x 10) + (ED2.6 x CR x 3)]/BW) x CF / (AT)
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
CF
Conversion Factor
kg/mg
1.0E-06
U.S. EPA 1989
Dermal
CS
Chemical Concentration in Soil
mg/kg
Chemical-Specific
Chemical-Specific
CDI (mg/kg/day) =
SA
Surface Area for Contact
cm2/event
2,373
U.S. EPA 2015a
CS x SA x AF x ABS x EF x ED x CF / (BW x AT)
AF
Adherence Factor
mg/cm2
0.2
U.S. EPA 2004(1)
EF
Exposure Frequency
event/yr
350
U.S. EPA 1991a
ED-NC
Exposure Duration - Noncancer
y
6
U.S. EPA 1991a
ED-C
Exposure Duration - Cancer
y
6
U.S. EPA 1991a
BW
Body Weight
kg
15
U.S. EPA 1989
Mutagenic Chronic Daily Intake (MCDI) (mg/kg/day) =
AT-NC
Averaging time - Noncancer
days
2,190
U.S. EPA 1989
CS x EF x ABS x ([(ED0.2 x SA x AF x 10) + (ED2.6 x SA x AF x 3)]/BW) x CF / (AT)
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
CF
Conversion Factor
kg/mg
1.0E-06
U.S. EPA 1989
ABS
Dermal Absorption Fraction
unitless
Chemical-Specific
U.S. EPA 2004 (2)
Inhalation
CA
Chemical Concentration in Air
mg/m3
Chemical-Specific
Chemical-Specific
Exposure Concentration (ng/m3 or mg/m3)
CF,
Conversion Factor
Hg/mg
1,000
U.S. EPA 2009a
CA x CF, x FT x FF x HI) AT x CF,
ET
Exposure Time
hr/day
24
U.S. EPA 2009a
Note: CFj only used in carcinogenic intake calculations
EF
Exposure Frequency
day/yr
350
U.S. EPA 1991a
ED-NC
Exposure Duration - Noncancer
y
6
U.S. EPA 1991a
ED-C
Exposure Duration - Cancer
y
6
U.S. EPA 1991a
BW
Body Weight
kg
15
U.S. EPA 1989
Mutagenic Exposure Concentration (MEC) (|ig/m3)
AT-NC
Averaging time - Noncancer
days
2,190
U.S. EPA 1989
CA x ET x EF x [(ED0.2 x 10) + (ED2.6 x 3)] x CF! / (AT x CF2)
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
cf2
Conversion Factor
hr/day
24
U.S. EPA 2009a
(1) Taken from Exhibit 3-5 of USEPA 2004.
(2) Taken from Exhibit 3-4 of USEPA 2004.
BPJ = Best Professional Judgment
U.S. EPA = United States Environmental Protection Agency
CDI = chronic daily intake
mg/kg = milligrams per kilogram
kg/mg = kilograms per milligram
mg/cm = milligrams per square centimeter
mg/day=milligrams per day
day/yr = days per year
RME = Reasonable Maximum Exposure
mg/m3 = milligram per cubic meter
jig/m = micrograms per cubic meter
cm2 /event = square centimeters per event
Hg/mg = microgram per milligram
kg = kilogram
hr/day = hours per day
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
Record of Decision
000787
-------
VALUES USED FOR AGRICULTURAL WORKER DAILY SOIL INTAKE EQUATIONS
Scenario Timeframe: Current/Future
Medium: Soil
Exposure Medium: Soil, Air
Exposure Point: Donna Reservoir and Canal System
Receptor Population: Agricultural Worker
Receptor Age: Adult
Exposure Route
Parameter
Code
Parameter Definition
Units
RME Value
RME
Rationale/Reference
Intake Equation / Model Name
Ingestion
CS
Chemical Concentration in Soil
mg/kg
Chemical-Specific
Chemical-Specific
CDI (mg/kg/day) -
CR
Ingestion Rate
mg/day
100
U.S. EPA 2011
CS x CR x EF x ED x CF / (BW x AT)
EF
Exposure Frequency
day/yr
250
U.S. EPA 1991a
ED
Exposure Duration
r
25
U.S. EPA 1991a
BW
Body Weight
kg
80
U.S. EPA 2011
AT-NC
Averaging time - Noncancer
days
10,950
U.S. EPA 1989
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
CF
Conversion Factor
kg/mg
1.0E-06
U.S. EPA 1989
Dermal
CS
Chemical Concentration in Soil
mg/kg
Chemical-Specific
Chemical-Specific
CDI (mg/kg/day) =
SA
Surface Area for Contact
cm2/event
3,527
U.S. EPA 2015a
CS x SA x AF x ABS x EF x ED x CF / (BW x AT)
AF
Adherence Factor
mg/cm2
0.12
U.S. EPA 2004 (1)
EF
Exposure Frequency
event/yr
250
U.S. EPA 1991a
ED
Exposure Duration
r
25
U.S. EPA 1991a
BW
Body Weight
kg
80
U.S. EPA 2011
AT-NC
Averaging time - Noncancer
days
10,950
U.S. EPA 1989
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
CF
Conversion Factor
kg/mg
1.0E-06
U.S. EPA 1989
ABS
Dermal Absorption Fraction
unitless
Chemical-Specific
U.S. EPA 2004 (2)
Inhalation
CA
Chemical Concentration in Air
mg/m3
Chemical-Specific
Chemical-Specific
Exposure Concentration (ng/m3 or mg/m3) =
CF,
Conversion Factor
Hg/mg
1,000
U.S. EPA 2009a
CA x CF, x ET x EF x ED / AT x CF2
ET
Exposure Time
hr/day
8
U.S. EPA 2009a
Note: CFj only used in carcinogenic intake calculations
EF
Exposure Frequency
day/yr
250
U.S. EPA 1991a
ED
Exposure Duration
yr
25
U.S. EPA 1991a
AT-NC
Averaging time - Noncancer
days
3,650
U.S. EPA 1989
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
cf2
Conversion Factor
hr/day
24
U.S. EPA 2009a
(1) Taken from Exhibit 3-5 of USEPA 2004.
(2) Taken from Exhibit 3-4 of USEPA 2004.
BPJ = Best Professional Judgment
U.S. EPA = United States Environmental Protection Agency
CDI = chronic daily intake
mg/kg - milligrams per kilogram
kg/mg - kilograms per milligram
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
mg/cm - milligrams per square centimeter
mg/day = milligrams per day
day/yr - days per year
RME - Reasonable Maximum Exposure
mg/m3 = milligram per cubic meter
Hg/m = micrograms per cubic meter
cm2 /event - square centimeters per event
Hg/mg - microgram per milligram
kg - kilogram
hr/day = hours per day
Record of Decision
000788
-------
VALUES USED FOR ADULT RECREATIONAL USER
DAILY SURFACE WATER INTAKE EQUATIONS
Scenario Timeframe: Current/Future
Medium: Surface Water
Exposure Medium: Surface Water
Exposure Point: Donna Reservoir and Canal System
Receptor Population: Recreational User
Receptor Age: Adult
Exposure Route
Parameter
Code
Parameter Definition
Units
RME Value
RME
Rationale/Reference
Intake Equation
Ingestion
CW
Concentration in Water
mg/L
Chemical-Specific
Chemical-Specific
CDI (mg/kg/day)
CR
Ingestion Rate
L/day
0.043
U.S. EPA 2011 (1)
CW x C R x HI x IT) (BW x AT)
EF
Exposure Frequency
day/yr
52
BPJ (2)
ED
Exposure Duration
yr
26
U.S. EPA 2011
BW
Body Weight
kg
80
U.S. EPA 2011
AT-NC
Averaging time-Noncancer
days
9,490
U.S. EPA 1989
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
Dermal
CW
Concentration in Surface Water
mg/L
Chemical-Specific
Chemical-Specific
CDI (mg/kg/day)
SA
Surface Area for Contact
cm2
6,032
U.S. EPA 2011 (3)
CW x SA x PC x I T x I I x hi) x CI (BW x AT)
PC
Permeability Coefficient
cm/hr
Chemical-Specific
Chemical-Specific
ET
Exposure Time
hr/day
4
U.S. EPA 2011 (1)
For organic compounds
EF
Exposure Frequency
day/yr
52
BPJ (2)
CDI (mg/kg/day)
ED
Exposure Duration
yr
26
U.S. EPA 2011
DA,..,.... x SA x IT x IT) / (BW x AT)
BW
Body Weight
kg
80
U.S. EPA 2011
AT-NC
Averaging Time - Noncancer
days
9,490
U.S. EPA 1989
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
CF
Conversion Factor
L/cm3
0.001
U.S. EPA 1989
(1) The incidental ingestion rate of surface water is taken from the USEPA Exposure Factors Handbook, Table 3-93. Ingestion of surface water is assumed during fishing activities, which has an
ingestion rate of 10.8 mL/hr. Assuming an exposure time of 4 hour/day results in an ingestion rate of 43.2 mL/day.
(2) Assumes fishing will occur approximately 2 days per week for 6 months.
(3) Assumes contact with head, hands, forearms, lower legs, and feet.
BPJ = Best Professional Judgment
U.S. EPA = United States Environmental Protection Agency
CDI = chronic daily intake
mg/L = milligrams per liter
day/yr = days per year
yr = year
kg = kilogram
RME = Reasonable Maximum Exposure
hr/day = hours per day
cm2 = square centimeters
cm/hr = centimeter per hour
L/cm3 = liters per cubic centimeter
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas Record of Decision
000789
-------
VALUES USED FOR ADOLESCENT RECREATIONAL USER
DAILY SURFACE WATER INTAKE EQUATIONS
Scenario Timeframe: Current/Future
Medium: Surface Water
Exposure Medium: Surface Water
Exposure Point: Donna Reservoir and Canal System
Receptor Population: Recreational User
Receptor Age: Adolescent
Parameter
RME
Intake Equation
Exposure Route
Code
Parameter Definition
Units
RME Value
Rationale/Reference
Ingestion
CW
Concentration in Water
mg/L
Chemical-Specific
Chemical-Specific
CDI (mg/kg/day)=
CR
Ingestion Rate
L/day
0.043
U.S. EPA 2011 (1)
CW x CR x EF x ED / (BW x AT)
EF
Exposure Frequency
day/yr
52
BPJ (2)
ED
Exposure Duration
yr
10
BPJ (3)
BW
Body Weight
kg
45
U.S. EPA 2011
AT-NC
Averaging time-Noncancer
days
3,650
U.S. EPA 1989
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
Dermal
CW
Concentration in Surface Water
mg/L
Chemical-Specific
Chemical-Specific
CDI (mg/kg/day) =
SA
Surface Area for Contact
cm2
3,800
U.S. EPA 2011 (4)
CW x SA x PC x ET x EF x ED x CF / (BW x AT)
PC
Permeability Coefficient
cm/hr
Chemical-Specific
Chemical-Specific
ET
Exposure Time
hr/day
4
U.S. EPA 2011 (1)
For organic compounds
EF
Exposure Frequency
day/yr
52
BPJ (2)
CDI (mg/kg/day) =
ED
Exposure Duration
yr
10
BPJ (3)
DAcvcnt x SA x EF x ED / (BW x AT)
BW
Body Weight
kg
45
U.S. EPA 2011
AT-NC
Averaging Time - Noncancer
days
3,650
U.S. EPA 1989
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
CF
Conversion Factor
L/cm3
0.001
U.S. EPA 1989
(1) The incidental ingestion rate of surface water is taken from the USEPA Exposure Factors Handbook, Table 3-93. Ingestion of surface water is assumed during fishing activities, which has an
ingestion rate of 10.8 mL/hr. Assuming an exposure time of 4 hour/day results in an ingestion rate of 43.2 mL/day.
(2) Assumes fishing will occur approximately 2 days per week for 6 months.
(3) Assumes age range of adolescent is 6 to 16 years of age.
(4) Skin surface area is taken from Table 7-17 and Table 7-9 of 2011 EFH. Table 7-17 notes 29% of exposed skin surface available for 5 to 17 year old during outdoor activities. Table 7-9 presents
the total skin surface area for 6 to <11 years of age and 11 to <16 years of age for male and female combined.
BPJ = Best Professional Judgment
U.S. EPA = United States Environmental Protection Agency
CDI = chronic daily intake
mg/L = milligrams per liter
day/yr = days per year
yr = year
kg = kilogram
RME = Reasonable Maximum Exposure
hr/day = hours per day
cm2 = square centimeters
cm/hr = centimeter per hour
L/cm3 = liters per cubic centimeter
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
Record of Decision
000790
-------
VALUES USED FOR CHILD RECREATIONAL USER
DAILY SURFACE WATER INTAKE EQUATIONS
Scenario Timeframe: Current/Future
Medium: Surface Water
Exposure Medium: Surface Water
Exposure Point: Donna Reservoir and Canal System
Receptor Population: Recreational User
Receptor Age: Child
Exposure Route
Parameter
Code
Parameter Definition
Units
RME Value
RME
Rationale/Reference
Intake Equation
Ingestion
CW
Concentration in Water
mg/L
Chemical-Specific
Chemical-Specific
CDI (mg/kg/day) =
CR
Ingestion Rate
L/day
0.043
U.S. EPA 2011 (1)
CW x CR x EF x ED / (BW x AT)
EF
Exposure Frequency
day/yr
52
BPJ (2)
ED
Exposure Duration
yr
4
BPJ (3)
BW
Body Weight
kg
18
U.S. EPA 1989
AT-NC
Averaging time-Noncancer
days
1,460
U.S. EPA 1989
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
Dermal
CW
Concentration in Surface Water
mg/L
Chemical-Specific
Chemical-Specific
CDI (mg/kg/day)
SA
Surface Area for Contact
cm2
2,373
U.S. EPA 2004
( W x SA x PC x I.T x I.I x I I) x ( I (Ii\V x AT)
PC
Permeability Coefficient
cm/hr
Chemical-Specific
Chemical-Specific
ET
Exposure Time
hr/day
4
U.S. EPA 2011 (1)
For organic compounds
EF
Exposure Frequency
day/yr
52
BPJ (2)
CDI (mg/kg/day) =
ED
Exposure Duration
yr
4
BPJ (3)
DAevem x SA x EF x ED / (BW x AT)
BW
Body Weight
kg
15
U.S. EPA 2011
AT-NC
Averaging Time - Noncancer
days
1,095
U.S. EPA 1989
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
CF
Conversion Factor
L/cm3
0.001
U.S. EPA 1989
(1) The incidental ingestion rate of surface water is taken from the USEPA Exposure Factors Handbook, Table 3-93. Ingestion of surface water is assumed during fishing activities, which has an
ingestion rate of 10.8 mL/hr. Assuming an exposure time of 4 hour/day results in an ingestion rate of 43.2 mL/day.
(2) Assumes fishing will occur approximately 2 days per week for 6 months.
(3) Age range for child is assumed from 2 to 6 years. It is expected that children younger then 2 years will not have contact with surface water.
BPJ = Best Professional Judgment
U.S. EPA = United States Environmental Protection Agency
CDI = chronic daily intake
mg/L = milligrams per liter
day/yr = days per year
yr = year
kg = kilogram
RME = Reasonable Maximum Exposure
hr/day = hours per day
cm2 = square centimeters
cm/hr = centimeter per hour
L/cm3 = liters per cubic centimeter
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas Record of Decision
000791
-------
VALUES USED FOR ADULT RECREATIONAL USER
DAILY SEDIMENT INTAKE EQUATIONS
Scenario Timeframe: Current/Future
Medium: Sediment
Exposure Medium: Sediment
Exposure Point: Donna Reservoir and Canal System
Receptor Population: Recreational User
Receptor Age: Adult
Parameter
Exposure Route
Code
Parameter Definition
Units
RME Value
RME Rationale/Reference
Intake Equation
Ingestion
CS
Chemical Concentration in Sediment
mg/kg
Chemical-Specific
Chemical-Specific
CDI (mg/kg/day) =
CR
Ingestion Rate
mg/day
50
BPJ (1)
CS x CR x EF x ED x CF / (BW x AT)
EF
Exposure Frequency
day/yr
52
BPJ (2)
ED
Exposure Duration
yr
26
U.S. EPA 2011
BW
Body Weight
kg
80
U.S. EPA 2011
AT-NC
Averaging time - Noncancer
days
9,490
U.S. EPA 1989
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
CF
Conversion Factor
kg/mg
1.0E-06
U.S. EPA 1989
Dermal
CS
Chemical Concentration in Sediment
mg/kg
Chemical-Specific
Chemical-Specific
CDI (mg/kg/day) -
SA
Surface Area for Contact
cm2/event
4,782
U.S. EPA 2011 (3)
CS x SA x AF x ABS x EF x ED x CF / (BW x AT)
AF
Adherence Factor
mg/cm2
0.07
U.S. EPA 2004 (4)
ABS
Dermal Absorption Fraction
Unitless
Chemical-Specific
U.S. EPA 2004
EF
Exposure Frequency
event/yr
52
BPJ (2)
ED
Exposure Duration
yr
26
U.S. EPA 2011
BW
Body Weight
kg
80
U.S. EPA 2011
AT-NC
Averaging Time - Noncancer
days
9,490
U.S. EPA 1989
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
CF
Conversion Factor
kg/mg
1.0E-06
U.S. EPA 1989
(1) The incidental sediment ingestion rate is assumed to be equal to the soil ingestion rate presented in Table 5-1 of USEPA Exposure Factors Handbook and does not take into account dust ingestion.
(2) Assumes fishing will occur approximately 2 days per week for 6 months.
(3) Contact with sediment will be with the hands, forearms, feet and lower legs.
(4) The adherence factor is conservatively equal to the recommended factor for resident adult exposure to soil.
BP J = Best Professional Judgment
U.S. EPA = United States Environmental Protection Agency
CDI = chronic daily intake
mg/kg = milligrams per kilogram
mg/cm = milligrams per square centimeter
mg/day = milligrams per day
day/yr = days per year
RME = Reasonable Maximum Exposure
kg/mg = kilograms per milligram
cm2 /event = square centimeters per event
kg = kilogram
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas Record of Decision
000792
-------
VALUES USED FOR ADOLESCENT RECREATIONAL USER
DAILY SEDIMENT INTAKE EQUATIONS
Scenario Timeframe: Current/Future
Medium: Sediment
Exposure Medium: Sediment
Exposure Point: Donna Reservoir and Canal System
Receptor Population: Recreational User
Receptor Age: Adolescent
Parameter
Exposure Route
Code
Parameter Definition
Units
RME Value
RME Rationale/Reference
Intake Equation
Ingestion
CS
Chemical Concentration in Sediment
Chemical-Specific
Chemical-Specific
Chemical-Specific
CDI (mg/kg/day) -
CR
Ingestion Rate
mg/day
50
BPJ (1)
CS x CR x EF x ED x CF / (BW x AT)
EF
Exposure Frequency
day/yr
52
BPJ (2)
ED
Exposure Duration
yr
10
BPJ (3)
BW
Body Weight
kg
45
U.S. EPA 2011
AT-NC
Averaging time - Noncancer
days
2,920
U.S. EPA 1989
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
CF
Conversion Factor
kg/mg
1.0E-06
U.S. EPA 1989
Dermal
CS
Chemical Concentration in Sediment
mg/kg
Chemical-Specific
Chemical-Specific
CDI (mg/kg/day) -
SA
Surface Area for Contact
cm2/event
3,870
U.S. EPA 2011 (4)
CS x SA x AF x ABS x EF x ED x CF / (BW x AT)
AF
Adherence Factor
mg/cm2
0.2
U.S. EPA 2004 (5)
ABS
Dermal Absorption Fraction
Unitless
Chemical-Specific
U.S. EPA 2004
EF
Exposure Frequency
event/yr
52
BPJ (2)
ED
Exposure Duration
yr
10
BPJ (3)
BW
Body Weight
kg
45
U.S. EPA 2011
AT-NC
Averaging Time - Noncancer
days
3,650
U.S. EPA 1989
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
CF
Conversion Factor
kg/mg
1.0E-06
U.S. EPA 1989
(1) The incidental sediment ingestion rate is assumed to be equal to the soil ingestion rate presented in Table 5-1 of USEPA Exposure Factors Handbook and does not take into account dust ingestion.
(2) Assumes fishing will occur approximately 2 days per week for 6 months.
(3) Assumes age range of adolescent is 6 to 16 years of age.
(4) Skin surface area is taken from Table 7-17 and Table 7-9 of 2011 EFH. Table 7-17 notes 29% of exposed skin surface available for 5 to 17 year old during outdoor activities. Table 7-9 presents the total skin
surface area for 6 to <11 years of age and 11 to <16 years of age for male and female combined.
(5) The adherence factor is conservatively equal to the recommended factor for resident child exposure to soil.
BP J = Best Professional Judgment
U.S. EPA = United States Environmental Protection Agency
CDI = chronic daily intake
mg/kg - milligrams per kilogram
mg/cm = milligrams per square centimeter
mg/day - milligrams per day
day/yr = days per year
RME - Reasonable Maximum Exposure
kg/mg = kilograms per milligram
cm2 /event - square centimeters per event
kg = kilogram
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas Record of Decision
000793
-------
VALUES USED FOR CHILD RECREATIONAL USER
DAILY SEDIMENT INTAKE EQUATIONS
Scenario Timeframe: Current/Future
Medium: Sediment
Exposure Medium: Sediment
Exposure Point: Donna Reservoir and Canal System
Receptor Population: Recreational User
Receptor Age: Child
Parameter
Intake Equation
Exposure Route
Code
Parameter Definition
Units
RME Value
RME Rationale/Reference
Ingestion
CS
Chemical Concentration in Sediment
Chemical-Specific
Chemical-Specific
Chemical-Specific
CDI (mg/kg/day) =
CR
Ingestion Rate
mg/day
50
BPJ (1)
CS x CR x EF x ED x CF / (BW x AT)
EF
Exposure Frequency
day/yr
52
BPJ (2)
ED
Exposure Duration
yr
4
BPJ (3)
BW
Body Weight
kg
15
U.S. EPA 2011
AT-NC
Averaging time - Noncancer
days
2,920
U.S. EPA 1989
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
CF
Conversion Factor
kg/mg
1.0E-06
U.S. EPA 1989
Dermal
CS
Chemical Concentration in Sediment
mg/kg
Chemical-Specific
Chemical-Specific
CDI (mg/kg/day) =
SA
Surface Area for Contact
cm2/event
2,373
U.S. EPA 2011 (4)
CS x SA x AF x ABS x EF x ED x CF / (BW x AT)
AF
Adherence Factor
mg/cm2
0.2
U.S. EPA 2004 (5)
ABS
Dermal Absorption Fraction
Unitless
Chemical-Specific
U.S. EPA 2004
EF
Exposure Frequency
event/yr
52
BPJ (2)
ED
Exposure Duration
yr
4
BPJ (3)
BW
Body Weight
kg
15
U.S. EPA 2011
AT-NC
Averaging Time - Noncancer
days
1,095
U.S. EPA 1989
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
CF
Conversion Factor
kg/mg
1.0E-06
U.S. EPA 1989
(1) The incidental sediment ingestion rate is assumed to be equal to the soil ingestion rate presented in Table 5-1 of USEPA Exposure Factors Handbook and does not take into account dust ingestion.
(2) Assumes fishing will occur approximately 2 days per week for 6 months.
(3) Age range for child is assumed from 2 to 6 years. It is expected that children younger then 2 years will not have contact with surface water.
(4) Contact with sediment is assumed similar to a resident child exposed area for soil.
(5) The adherence factor is conservatively equal to the recommended factor for resident child exposure to soil.
BPJ = Best Professional Judgment
U.S. EPA = United States Environmental Protection Agency
CDI = chronic daily intake
mg/kg - milligrams per kilogram
mg/cm - milligrams per square centimeter
mg/day - milligrams per day
day/yr = days per year
RME - Reasonable Maximum Exposure
kg/mg - kilograms per milligram
cm2 /event - square centimeters per event
kg - kilogram
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas Record of Decision
000794
-------
VALUES USED FOR ADULT RECREATIONAL USER
DAILY FISH INTAKE EQUATIONS
Scenario Timeframe: Current/Future
Medium: Surface Water/Sediment
Exposure Medium: Fish
Exposure Point: Donna Reservoir and Canal System
Receptor Population: Recreational User
Receptor Age: Adult
Exposure Route
Parameter
Code
Parameter Definition
Units
RME Value
RME Rationale/Reference
Intake Equation
Ingestion
CS
Chemical Concentration in Fish Fillets
mg/kg
Chemical-Specific
Chemical-Specific
CDI (mg/kg/day) =
CR
Ingestion Rate
kg/meal
0.0263
U.S. EPA 2000
CS x CR x EF x ED / (BW x AT)
EF
Exposure Frequency
meals/yr
365
U.S. EPA 2000
ED
Exposure Duration
yr
26
U.S. EPA 1989
BW
Body Weight
kg
80
U.S. EPA 1997b
AT-NC
Averaging time - Noncancer
days
9,490
U.S. EPA 1989
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
BPJ ~ Best Professional Judgment mg/kg = milligrams per kilogram yr = year
U.S. EPA = United States Environmental Protection Agency kg/meal = kilograms per meal kg = kilogram
CDI - chronic daily intake
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas Record of Decision
000795
-------
VALUES USED FOR ADOLESCENT RECREATIONAL USER
DAILY FISH INTAKE EQUATIONS
Scenario Timeframe: Current/Future
Medium: Surface Water/Sediment
Exposure Medium: Fish
Exposure Point: Donna Reservoir and Canal System
Receptor Population: Recreational User
Receptor Age: Adolescent
Exposure Route
Parameter
Code
Parameter Definition
Units
RME Value
RME Rationale/Reference
Intake Equation
Ingestion
CS
Chemical Concentration in Fish Fillets
mg/kg
Chemical-Specific
Chemical-Specific
CDI (mg/kg/day) =
CR
Ingestion Rate
kg/meal
0.0196
U.S. EPA 2000
CS x CR x EF x ED / (BW x AT)
EF
Exposure Frequency
meals/yr
365
U.S. EPA 2000
ED
Exposure Duration
yr
10
BPJ
BW
Body Weight
kg
45
U.S. EPA 1997b
AT-NC
Averaging time - Noncancer
days
3,650
U.S. EPA 1989
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
BPJ = Best Professional Judgment mg/kg = milligrams per kilogram yr = year
U.S. EPA = United States Environmental Protection Agency kg/meal = kilograms per meal kg = kilogram
CDI = chronic daily intake
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas Record of Decision
000796
-------
VALUES USED FOR CHILD RECREATIONAL USER
DAILY FISH INTAKE EQUATIONS
Scenario Timeframe: Current/Future
Medium: Surface Water/Sediment
Exposure Medium: Fish
Exposure Point: Donna Reservoir and Canal System
Receptor Population: Recreational User
Receptor Age: Child
Exposure Route
Parameter
Code
Parameter Definition
Units
RME Value
RME Rationale/Reference
Intake Equation
Ingestion
CS
Chemical Concentration in Fish Fillets
mg/kg
Chemical-Specific
Chemical-Specific
CDI (mg/kg/day) =
CR
Ingestion Rate
kg/meal
0.0098
U.S. EPA 2000
CS x CR x EF x ED / (BW x AT)
EF
Exposure Frequency
meals/yr
365
U.S. EPA 2000
ED
Exposure Duration
yr
4
BPJ (1)
BW
Body Weight
kg
15
U.S. EPA 2008
AT-NC
Averaging time - Noncancer
days
1,095
U.S. EPA 1989
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
(1) Age range for child is assumed from 2 to 6 years. It is expected that children younger then 2 years will not consume significant amounts of fish.
BPJ = Best Professional Judgment mg/kg = milligrams per kilogram yr = year
U.S. EPA = United States Environmental Protection Agency kg/meal = kilograms per meal kg = kilogram
CDI = chronic daily intake
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
000797
Record of Decision
-------
VALUES USED FOR ADULT SUBSISTENCE FISHER
DAILY FISH INTAKE EQUATIONS
Scenario Timeframe: Current/Future
Medium: Surface Water/Sediment
Exposure Medium: Fish
Exposure Point: Donna Reservoir and Canal System
Receptor Population: Subsistence
Receptor Age: Adult
Exposure Route
Parameter
Code
Parameter Definition
Units
RME Value
RME Rationale/Reference
Intake Equation / Model Name
Ingestion
CS
Chemical Concentration in Fish Fillets
mg/kg
Chemical-Specific
Chemical-Specific
CDI (mg/kg/day) =
CR
Ingestion Rate
kg/meal
0.146
U.S. EPA 2000, BPJ
CS x CR x EF x ED / (BW x AT)
EF
Exposure Frequency
meals/yr
365
U.S. EPA 2000
ED
Exposure Duration
yr
20
U.S. EPA 2011
BW
Body Weight
kg
80
U.S. EPA 2011
AT-NC
Averaging time - Noncancer
days
7,300
U.S. EPA 1989
AT-C
Averaging Time - Cancer
days
25,550
U.S. EPA 1989
(1) The subsistence fisher is assumed to ingest an average of 146 grams of fish over an entire year.
BP J = Best Professional Judgment mg/kg = milligrams per kilogram
U.S. EPA = United States Environmental Protection Agency kg/meal = kilograms per meal
CDI = chronic daily intake
yr = year
kg = kilogram
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
000798
Record of Decision
-------
Appendix B
Selection of Chemicals of Potential Concern for Ecological Receptors
000799
-------
Selection of Chemicals of Potential Concern for
Exposure Area 1: Upstream of the Siphon
Analyte
Benthos Tisane
Fish Tissue
Surface Soil
Sediment
Surface Water (Total)
Surface Water (Dissolved)
Selection of Chemicals
of Potential Concern
Frequency
Maximum
(mg/kg)
95UCLM
(mg/kg)
Frequency
Maximum
(mg/kg dry
wt)
95UCLM Maximum 95UCLM
(mg/kg dry (mg/kg wet (mg/kg wet
wt) wt) wt)
Frequency
Maximum
(mg/kg)
9SUCLM
(mg/kg)
Screening Criteria
(mg/kg)
Frequency
Maximum
(nig/kg)
95UCLM
(mg/kg)
Screening
Criteria
Frequency
Maximum
G»g/L)
95UCLM
0*g/L)
Screening
Criteria
Frequency
Maximum
Gig/L)
95UCLM
Gig/L)
Screening
Criteria
(lis/L)
Aquatic Habitats
Metals
Aluminum
-
-
-
2/2
2.16E+01
2.16E+01
5.40E+00
5.40E+00
-
-
-
3.00E+04
11/11
1.41E+04
1.03E+04
NA
4/4
1.38E+03
1.38E+03
8.70E+O1
-
-
-
8.70E+O1
YES
Arsenic
-
-
-
-
-
-
-
-
-
1.80E+01
11/11
5.30E+00
4.24E+00
9.79E+00
4/4
4.70E+00
4.70E+00
1.50E+02
4/4
4.30E-tfl0
4.30E-KJ0
1^0E+02
NO
Barium
—
—
—
2/2
7.20E+00
7.20E+00
1.80E+00
1.80E+00
—
—
—
3.30E+02
11/11
1.66E+02
1.66E+02
NA
4/4
1.40E+02
1.40E+02
1.60E+04
4/4
1.25E+02
1.25E+02
1.60E+04
YES
Beryllium
—
—
—
—
—
—
1.00E+01
1/11
7.10E-01
7.10E-01
NA
—
—
S30E+00
—
-
—
S30E+00
YES
Cadmium
—
—
—
—
—
—
—
—
—
3-20F.+01
2/11
3.30E-01
3.30E-01
950E-01
—
—
—
1.50E-01
—
—
—
1.50E-01
NO
Calcium
—
—
—
212
7.20E+04
7.20E+04
1.80E+04
1.80E+04
—
—
—
NA
11/11
8.07E+04
6.37E+04
NA
4/4
8.55E+04
8.55E+04
NA
4/4
8-27E+04
8-27E+04
NA
NO, Essential Nutrient
Chromium
—
—
—
2J2
1.12E+01
1.12E+01
2.80E+00
2.80E+00
—
—
—
4.00E-01
11/11
9.90E+00
8.03E+00
434E+01
1/4
6.30E-01
6.30E-01
420E+01
1/4
3.40E-01
3.40E-01
420E+01
NO
Cobalt
—
—
—
1/2
1.76E-01
1.76E-01
4.40E-02
4.40E-02
—
—
—
1.30E+01
11/11
6.00E+00
5.35E+00
5.00E+01
—
—
—
1.50E+03
—
—
—
1 _S0F,+03
NO
Capper
—
—
—
212
8.40E+00
8.40E+00
2.10E+00
2.10E+00
—
—
—
7.00E+01
9/11
8.80E+00
6.97E+00
3.16E+01
3/4
3.00E+00
3.00E+00
S24E+00
2/4
2.40E+00
2.40E+00
S24E+00
NO
Iron
—
—
—
2J2
2.08E+02
2.08E+02
5.20E+01
5.20E+01
—
—
—
1.50E+04
11/11
1.67E+04
1.33E+04
2.00E+04
4/4
1.16E+03
1.16E+03
1.00E+O3
1/4
1.37E-t02
1.37E-t02
1.00E+O3
NO, Essential Nutrient
Lead
—
—
—
1/2
1.48E-01
1.48E-01
3.70E-02
3.70E-02
—
—
—
1.20E+02
11/11
9-OOEOO
7.80E+00
3.58E+01
4/4
1.40E+00
1.40E+00
1.17E+00
—
—
—
1.17E+00
YES
Magnesium
—
—
—
2/2
4.80E+03
4.80E+03
1.20E+03
UOE+03
—
—
—
NA
11/11
6.26E+03
4.21E+03
NA
4/4
3.20E+04
3.20E+04
324E+03
4/4
3.18E+04
3.18E+04
324E+03
NO, Essential Nutrient
Manganese
—
—
—
2/2
1.12E+01
1.12E+01
2.80E+00
2.80E+00
—
—
—
2.20F.+02
11/11
3.54E+02
2.89E+02
4.60E+02
4/4
1.06E02
1.06E+02
IMF,+02
4/4
8.4OE-KJ0
8.4OE-KJ0
IMF,+02
NO
Mercury
—
—
—
2/2
1.88E+00
1.88E+00
4.70E-01
4.70E-01
—
—
—
1.00E-01
11/11
1.50E-01
6.30E-02
1.80E-01
—
—
—
130E+00
—
—
—
130E+00
NO
Nickel
—
—
—
2/2
1.04E+00
1.04E+00
2.60E-01
2.60E-01
—
—
—
3.80E+01
11/11
1.08E+01
8.28E+00
227E+01
4/4
1.6QE+00
1.60E+00
2.89E+01
1/4
1.10E+00
1.10E+00
2.89E+01
NO
Potassium
—
—
—
in
1.16E+04
1.16E+04
2.90E+03
2.90E+03
—
—
—
NA
9/11
2.98E+03
2.31E+03
NA
4/4
7.17E+03
7.17E+03
NA
4/4
6.90E-KJ3
6.90E-t03
NA
NO, Essaitial Nutrient
Selenium
—
—
—
2/2
1.40E+00
1.40E+00
3.50E-01
3.50E-01
—
—
—
5.20E-01
—
—
—
NA
3/4
1.60E+00
1.60E+00
5.00E+00
3/4
1.50E+00
1.50E+00
S.00E+O0
NO
Sodium
—
—
—
2/2
5.20E+03
5.20E+03
1.30E+03
1.30E+03
—
—
—
NA
1/11
7.72E+02
7.72E+02
NA
4/4
1.70E+05
1.70E+05
NA
4/4
1.74E-t<)5
1.74E-tOS
NA
NO, Essential Nutrient
Varm/tinm
—
—
—
2/2
2.24E+00
2.24E+00
5.60E-01
5.60E-01
—
—
—
2.00E+00
11/11
1.98E+01
1.71E+01
NA
4/4
9.6OEO0
9.60E+00
2.00E+01
4/4
9-OOE-tOO
9-OOE-tOO
2.00E+01
YES
Zinc
-
-
-
2/2
8.00E+01
8.00E+01
2.00E+01
2.00E+01
-
-
-
1.20E+02
11/11
3.90E+01
3.73E+01
1.21E+02
4/4
4.10E+00
4.10E+00
6.57E+01
3/4
2.30E+00
2.30E+00
6.57E+01
NO
PCBS
Aroclor-1260
-
-
-
-
-
-
-
-
-
-
4.00E+01
1/22
7.40E-04
7.40E-04
S.00E-03
-
-
-
1.40E-02
-
-
-
1.40E-02
YES, main COPC
Total PCB Congeners
-
-
-
-
-
-
-
-
-
-
-
4.00E+01
10/10
7.70E-03
3.27E-03
5.98E-02
9/9
4.40E-04
3.45E-04
1.40E-02
-
-
-
1.40E-02
YES, main COPC
Total PCB Aroclora
-
-
-
-
-
-
-
-
-
-
-
4.00E-t01
1/1
7.40E-04
7.40E-04
5.98E-02
-
-
-
1.40E-02
-
-
-
1.40E-02
YES, main COPC
PESTICIDES
DDTr
-
-
-
m
3.98E-01
3.98E-01
9.94E-02
9.94E-02
-
-
-
NA
9/13
5.40E-02
5.40E-02
5.28E-03
-
-
-
NA
-
-
-
NA
YES
deha-BHC
-
-
-
-
-
-
-
-
-
-
-
NA
1/13
9.10E-04
9.10E-04
3.00E-03
-
-
-
1.41E+02
-
-
-
1.41E+02
NO
PAILs
Total HMW PAHs _ | 1.80E-t01
1/1 | 7.19E-01 | 7.19E-01 | 1.70E-HX) | - | - | - | NA | - | - | - | NA | NO
svocs
Bis(2-ethylhexyl)phthalate
-
-
-
~
-
-
-
-
-
-
-
NA
6/13
6.10E-01
3.00E-01
1.80E-01
-
-
-
3.00E+02
-
-
-
3.00E+02
YES
Diethyl phlhalate
—
—
—
1/2
3.04E-01
3.04E-01
7.60E-02
7.60E-02
—
—
—
1.00E+02
-
-
—
630E-01
1/4
1.10E+00
1.10E+00
1.04E+03
—
-
—
1.04E+03
NO
Phenol
-
-
-
1/2
4.80E-02
4.80E-02
OOE-02
OOE-02
-
-
-
3.00E+01
4/13
6.70E-02
6.70E-02
NA
-
-
-
1.10E+02
-
-
-
1.10E+02
YES
vocs
Acetone
—
NA
1/4
5.20E-02
5.20E-02
6.00E+01
1.01E+05
1.01E+05
NO
Acetophenone
-
-
-
-
-
-
-
-
-
-
-
NA
6/13
8.30E-02
7.41E-02
NA
-
-
-
NA
-
-
-
NA
YES
Methylene chloride
—
—
—
-
-
-
-
—
—
—
—
NA
1/4
4.40E-03
4.40E-03
7.75E+00
—
-
—
1.10E+04
—
-
—
1.10E+04
NO
Toluene
-
-
-
-
-
-
-
-
-
-
-
2.00E+02
1/4
2.70E-03
2.70E-03
2.88E+00
-
-
-
1.45E+03
-
-
-
1.4SE+03
NO
Note:
95UCLM: 95 percent upper confidence limit on the mean
No data available
COPC: Chemical of potential concern
Selection of Chemicals of Potential Concern: if an analyte exceeds the screening criteria in any media or no screening is available, the analyte is retained as a COPC
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas Record of Decision
000800
-------
Selection of Chemicals of Potential Concern for
Exposure Area 2: Arroyo Colorado
Analyte
Benthos Tissue
Fish Tissue
Surface Soil
Sediment
Surface Water (Total)
Surface Water (Dissolved)
Selection of Chemicals
of Potential Concern
Frequency
Maximum
(mg/kg)
95UCLM
(mg/kg)
Frequency
Maximum
(mg/kg
dry wt)
(mg/kg
dry wt)
Maximum
(mg/kg
wetwt)
(mg/kg
wetwt)
Frequency
Maximum
(mg/kg)
95UCLM
(mg/kg)
Screening Criteria
(mg/kg)
Frequency
Maximum
(mg/kg)
95UCLM
(mg/kg)
Screening
Criteria
(mg/kg)
Frequency
Maximum
(/•g/L)
95UCLM
0*g/L)
Screening
Criteria
Oig/L)
Frequency
Maximum
0*g/L)
95UCLM
Oig/L)
Screening
Criteria
(Mg/L)
Aquatic Habitats
Meats
Aluminum
-
-
-
2/2
2.28E+02
2.28E+02
5.70E+01
5.70E+01
-
-
-
3.00E+04
14/14
2.40E+03
2.40E+03
NA
7/7
2.21E+03
1.37E+03
8.70E+01
-
-
-
8.70E+01
YES
Arsenic
-
-
-
2/2
3.68E-01
3.68E-01
9.20E-02
9.20E-G2
-
-
-
1.80E+01
14/14
6.60E+00
5.07E+00
9.79E+00
7/7
1.51E+01
1.39E+01
1.50E+02
7/7
1.27E+01
1Z7E+01
1.50E+02
NO
Barium
-
-
-
2/2
1.56E+01
1.56E+01
3.90E+00
3.90E+00
-
-
-
3.30E+02
14/14
2.55E+02
1.98E+02
NA
7/7
1.64E+02
1.41E+02
1.60E+04
7/7
1.52E+02
1Z0E+02
1.60E+04
YES
Beryllium
-
-
-
-
-
-
-
—
-
-
l.OOE+Ol
8/14
9.80E-01
7.85E-01
NA
-
-
—
530E+00
—
-
-
530E+00
YES
Cadmium
—
—
-
-
-
-
-
—
-
—
3.20E+01
14/14
4.90E-01
4.14E-01
9.90E-01
1/7
1.70E-01
1.70E-01
1.50E-01
—
-
-
1.50E-01
YES
Calcium
-
-
-
2/2
4.80E+04
4.80E+04
1.20E+04
1.20E+04
-
-
-
NA
14/14
1.00E+05
8.83E+04
NA
7/7
2.19E+05
1.85E+05
NA
7/7
2.02E+05
1.83E+05
NA
NO, essential nutrient
Chromium
-
-
-
1/2
1.84E-01
1.84E-01
4.60E-02
4.60E-02
-
-
—
4.00E-01
14/14
1.67E+01
1.29E+01
4J4E+01
2/7
2.70E+00
2.70E+00
4.20E+01
—
-
-
4O0E+01
NO
Cobalt
-
-
-
2/2
2.88E-01
2.88E-01
7.20E-02
7.20E-02
-
-
—
1.30E+01
14/14
7.20E+00
6.01E+00
5.00E+01
3/7
2.00E+00
2.00E+00
1.50E+03
—
-
-
1.50E+03
NO
Copper
-
-
-
2/2
3.52K+00
3.52E+00
8.80E-01
-
-
—
7.00E+01
14/14
1.26E+01
3.16E+01
7/7
9.20E+00
7.47E+00
5.24E+0Q
5.71E+00
5^4E+00
YES
Iron
-
-
-
2/2
3.00E+02
3.00E+02
7.50E+01
7.50E+01
-
-
—
1.50E+04
14/14
2.19E+04
1.82E+04
2.00E+04
6/7
1.80E+03
1.16E+03
1.00E+03
1/7
8.54E+02
8.54E+02
1.00E+03
NO, essential nutnent
Lead
-
-
-
2/2
5-20E-Q1
5J0E-01
130E-01
1.30E-01
-
-
—
1.20E+02
14/14
1.37E+01
1.07E+01
3.S8E+01
7/7
4.30E+00
2.82E+0Q
1.17E+00
1/7
2.50E-01
2.50E-01
1.17E+00
YES
Magnesium
—
—
-
2/2
1.52E+03
1.52E+03
3.80E+02
3.80E+02
—
-
—
NA
14/14
6.72E+03
NA
7/7
7.61E+04
6.22E+04
3.24E+03
7/7
7.62E+04
6.51E+04
3^4E+03
NO, essential nutnent
Manganese
—
—
—
2/2
9.20E+01
9.20E+01
2.30E+01
2.30E+01
—
—
—
2.20E+02
14/14
1.18E+03
6.82E+02
4.60E+02
7/7
3.42E+02
2.52E+02
1.20E+02
7/7
1.38E+02
8.93E+01
1^0E+02
YES
Mercury
-
-
-
2/2
1.68E-01
1.68E-01
420E-02
4.20E-02
-
-
-
1.00E-01
13/14
2.20E-01
1.12E-01
1.80E-01
1/7
6.00E-02
6.00E-02
UOE+OO
-
-
-
UOE+OO
YES
Nickel
-
-
-
1/5
1.52E-01
1.52E-01
3.80E-02
3.80E-02
-
-
—
3.80E+01
14/14
1.49E+01
1.23E+01
2.27E+01
7/7
4.30E+0Q
3.78E+00
2.89E+01
7/7
Z30E+00
2.08E+00
2.89E+01
NO
Potassium
—
—
-
2/2
1.04E+04
1.04E+04
2.60E+03
2.60E+03
—
-
—
NA
14/14
5.62E+03
4.33E+03
NA
7/7
1.38E+04
1.20E+04
NA
7/7
1.36E+04
1Z4E+04
NA
NO, essential nutnent
Selenium
-
-
-
2/2
1.48E+00
1.48E+00
3.70E-01
3.70E-01
-
-
—
5.20E-01
-
-
-
NA
2/7
5.60E+00
5.60E+00
5.00E+00
7/7
6.00E+00
6.00E+00
5.00E+00
YES
Sodium
-
-
-
2/2
4.8QE+03
4.80E+03
1.20E+03
1.20E+03
-
-
-
NA
14/14
2.12E+03
1.54E+03
NA
7/7
5.62E+05
4.37E+05
NA
7/7
5.49E+05
4.49E+05
NA
NO, essential nutnent
Vanadium
—
—
-
—
—
—
—
—
-
—
2.00E+00
14/14
2.85E+01
2.37E+01
NA
7/7
1.58E+01
2.00E+01
7/7
1.09E+01
2.00E+01
YES
Zinc
-
-
-
2/2
1.92E+02
1.92E+02
4.80E+01
4.80E+01
-
-
-
1.20E+02
14/14
7.45E+01
5.54E+01
1.21E+02
7/7
1.86E+01
1.49E+01
6.57E+01
7/7
6.40E+00
5.50E+00
6.57E+01
NO
PCBS
Aroclor-1260
-
-
-
1/2
3.04E-02
3.04E-02
7.60E-03
7.60E-03
-
-
-
4.00E+01
5/22
5.60E-03
4.58E-03
5.00B-03
-
-
-
1.40E-02
-
-
-
1.40E-02
YES
Total PCB Congeners
-
-
-
-
-
-
-
-
-
-
4.00E+01
4/4
1.20E-02
1.20E-02
5.98E-02
4/4
U0E-03
1.20E-03
1.40E-02
-
-
-
1.40E-02
YES, main COPC
Total PCB Aroclors
-
-
-
1/2
3.04E-02
3.04E-02
7.60E-03
7.60E-03
-
-
-
4.00E+01
5/22
5.60E-03
4.58E-03
5.98B-Q2
-
-
-
1.40E-02
-
-
-
1.40B-02
YES, main COPC
PESTICIDES
DDTr
-
-
-
2/2
1.57E+00
1.57E+00
3.92E-01
3.92E-01
-
-
-
NA
3/14
1.30E-02
1.30E-02
5.28E-03
-
-
-
NA
-
-
-
NA
YES
gamma-BHC (Lindane)
-
-
-
2/2
6.00E-04
6.00E-04
1.50E-04
1.50E-04
-
-
-
NA
-
-
-
237E-Q3
1/7
1.70E-02
1.70E-02
8.00E-02
-
-
-
8.00B-02
NO
svocs
Bis(2-ethylhexj1)phflLaLate | — | — | — l~ 1 — 1 — 1 — 1 — | — | — 1 - 1 NA
3/14 | 1.20E-01 | 1.20E-01 | 1.80&O1 | 3/7 | 1.40E+02 | 1.40E+02 | 3.00E+C2 | - | - | - | 3.00E+02 | NO
vocs
Acetone
-
-
-
-
-
-
-
-
-
-
NA
1/3
4.80E-02
4.80E-02
6.00E+01
-
-
-
1.01E+05
-
-
-
1.01E+05
NO
Acetophenone
-
-
-
1/2
2.32E-02
2.32E-02
5.8QE-03
5.80E-03
-
-
-
NA
-
-
-
NA
1/7
2.10E+00
2.10E+00
NA
-
-
-
NA
YES
Note:
95UCLM: 95 percent upper confidence limit on tie mean
No data available
COPC: Chemical of potential concern
Selection of Chemicals of Potential Concern: if an analyte exceeds the screening criteria in any media or no screening is available, the analyte is retained as a COP
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas Record of Decision
000801
-------
Selection of Chemkali of Potential Concern
for Exposure Ares 3: LWMCU at the Siphon Exit
Benthos Tlunc
Ibh Tisane
Surface Soil
Si din
lent
Snrfice W
UT (Total)
Surface Water (Diaiolred)
Selection of Chemlcab of
Potential Concern
Frequency
Maximum
dry wt)
95UCLM
(me/kg
dry wt)
(mg/kg
wet wt)
95TJCLM
wet wt)
Frequency
(mg/kg
drywt)
95TJCLM
(mg/kB
drywt)
Maximum
(mg/kg
wet wf)
95UCLM
(mg/kg
wet wt)
Frequency
Maximum
(mg/kg)
95UCLM
(mg/kg)
Screening Criteria
(mg/kg)
Frequency
Maximum
(mg/kg)
95UCLM
(mg/kg)
Screening
Criteria
(mg/kg)
Frequency
Mjiliimm
95UCLM
0f/L)
Screening
Criteria
(«?/'•)
Frequency
(w?/i)
95UCLM
(Hg/L)
Screening
Criteria
Aquatic Habitats
Metals
Aluminum
-
-
-
-
-
4/4
2.00E+03
2.00E+03
5.00E+02
5.00E+02
-
-
-
3.00E+04
11/11
1.40E+04
1.17E+04
NA
3/3
1.94E+03
1.94E+03
8.70E+01
-
-
-
8.70E+01
YES
Antimony
2/4
1.88E-01
1.88E-01
4.70E-02
4.7QE-Q2
5.00E+00
-
-
-
2.00E+00
-
-
-
1.60ET02
-
-
-
1.6QET02
NO
Arsenic
-
-
-
-
-
2/4
1.12E+00
1.12E+00
2.80E-01
2.80E-01
-
-
-
1.80E+01
11/11
4.70E+00
4.24E+00
9.79E+00
3/3
4.70E+00
4.70E+00
1.50E+02
3/3
4.10E+00
4.10E+00
1.50E+02
NO
Rjiriiim
-
-
4/4
2.64E+01
2.64E+01
6.60E+00
6.60E+00
-
3JOE+02
11/11
2.72B-KI2
1.86E+02
NA
3/3
1.52E+02
1.52E+02
1.60EI04
3/3
1.24E+02
1.24E+02
1.60E+04
YES
Beryllium
-
-
-
-
-
1/4
8.40E-02
8.40E-02
2.10E-02
2.10E-02
-
-
-
1.00E+01
1/U
6.00E-01
6.00IT01
NA
-
-
-
5J0E+00
-
-
-
5.30E+00
YES
Cadmium
-
-
-
-
-
1/4
5.20E-02
5.2OE-02
1.30E-02
1.30E-02
-
-
-
3.20E+01
11/11
3.80E-01
3.05E-01
9.90E-01
-
-
-
UOEfll
-
-
-
1.50E-01
NO
Calcium
4/4
4.80E+O4
4.80E+04
1.20E+04
1.20E+04
NA
11/11
1.68E+05
1.17B-KI5
NA
3/3
8.60E+04
8.60ET04
NA
3/3
8.20E+04
8.20E+04
NA
NO, essential nutrient
f!hmmiiim
-
-
-
-
-
4/4
3.00E+00
3.00E+00
7.50E-01
7.50E-01
-
-
-
4.00E-01
11/11
1.08E+01
8.54E+00
4.34E+01
-
-
-
4.20E+01
1/3
2.90E-01
2.90E-01
4.20E+01
NO
Cobalt
-
-
3/4
1.04E+00
1.04E+00
2.60E-01
2.60E-01
-
1.30EI01
11/11
7.70E+00
6.62E+00
5.00E+01
-
-
-
1.50E 103
-
-
-
1.50E+03
NO
Copper
-
-
-
-
-
4/4
1.24E+01
U4E-K11
3.10E+00
3.10E+00
-
-
-
7.00E+01
11/11
2.15E+01
1.17E+01
3.16E+01
3/3
2.80E+00
2.80T+00
5.24E+00
1/3
2.20E+00
2.20E+00
5.24E+00
NO
Iron
-
-
-
-
-
4/4
2.28E+03
2.28E+03
5.70E+02
5.70E+02
-
-
-
1.50E+04
11/11
1.65E+04
1.42E+04
2.00E+04
3/3
1.67E+03
1.67E+03
1.00E+03
-
-
-
1.00E+03
NO, essential nutrient
Lead
3/4
2.20E+00
2.20EIO0
5.50E-01
5.50E-01
1.20EI02
11/11
1.27B-KI1
9.84E+00
3.58E+01
3/3
1.80E+00
1.80ETOO
1.17E-KK)
-
-
-
1.17E+00
YES
Magnesium
-
-
-
-
-
4/4
1.76E+03
1.76E+03
4.40E+02
4.40E+02
-
-
-
NA
11/11
5.45E+03
4.49E+03
NA
3/3
3.11E+04
3.UE+04
3.24E-03
3/3
3.14E+04
3.14E+04
3.24E+03
NO, essential nutrient
Manganese
4/4
1.24E+02
1.24EI02
3.10E+01
3.10E+01
2.20EI02
11/11
6.95E+02
4.34E+02
4.60E+02
3/3
1.26E+02
1-26B+
-------
Selection of Chemicals of Potential Concern
for Expomire Area 4: LWMCU Down«tream of the Siphon
Analyte
Benthoi Tlftine
FlshTUsne
Surface Soil
Sediment
Surface Water (Total)
Surface Water (Dliaolyed)
Selection of Chemicals
of Potential Concern
Frequency
Maximum
(mg/kgdry
wt)
95UCLM
(mg/kgdry
wt)
Maximum
(mg/kg wet
wt)
95UCLM
(mg/kg wet
wt)
Frequency
Maximum
(mg/kgdry
wt)
95UCLM
(mg/kgdry
wt)
Maximum
(mg/kg wet
wt)
95UCLM
(mg/kg wet
wt)
Frequency
(mg/kg)
95UCLM
(mg/kg)
Screening Criteria
(mgfltg)
Frequency
(mg/kg)
9SUCLM
(rag/kg)
Screening
Criteria
(mg/kg)
Frequency
Maximum
0»g/L)
95UCLM
0»g/L)
Screening
Criteria
6»g/L)
Frequency
0»g/L)
95UCLM
0«g/L)
Screening
Criteria
G»g/L)
Aquatic Habitats
Meads
Aluminum
-
-
-
4/4
2.00E+03
2.00E+03
5.00E+02
5.00E+02
—
3.00E+04
8/8
2.19E+04
1.74E+04
NA
2/2
1.60 E+03
1.60E+03
8.70E+01
-
-
-
8.70E+01
YES
Araeiic
—
—
—
2/4
1.12E+00
1.12E+00
2.80E-01
2.80E-01
—
1.80E+01
8/8
4.90 F.-00
4.45E+00
9.79E+00
2/2
4.90 F.-00
4.90E+00
1J0E+02
2/2
4.20E+00
4.20E+00
1.50E+02
NO
Barium
—
—
—
4/4
2.64E+01
2.64E+01
6.60E+00
6.60E+00
-
330E+02
8/8
Z10E+02
1.81E+02
NA
2/2
1.46E+02
1.46E+02
1.60E04
2/2
1.28E+02
1.28E+02
1.60E+04
YES
Cadmium
-
-
-
1/4
5.20E-02
5.20E-02
1.30E-02
1.30E-02
-
3.20E+01
8/8
4.90 E-01
3.98E-01
9.90E-01
-
-
-
UOE-Ol
-
-
-
1J0E-01
NO
Calcium
-
-
-
4/4
4.80E+04
4.80E+04
1.20E+04
1.20E+04
—
NA
8/8
1.13E+05
9.39E+04
NA
2/2
8.76E+04
8.76E+04
NA
2/2
8.44E+04
8.44E+04
NA
NO, essential nutrient
nhmmnim
—
—
—
4/4
3.00E+00
3.00E+00
7.50E-01
7.50E-01
-
4.00E-01
8/8
1.51E+01
1.16E+01
434E+01
-
-
-
430E+01
1/2
3.90E-01
3.90E-01
4.20E+01
NO
Cobalt
—
—
—
3/4
1.04E+00
1.04E+00
2.60E-01
2.60E-01
-
130E+01
8//8
6.40E+00
6.03E+00
5.00E+01
-
-
-
1J0E+03
-
-
-
1.50E+03
NO
-
-
-
4/4
1.24E+01
1.24E+01
3.10E+00
3.10E+00
-
7.00E+01
8/8
1.42E+01
1.07E+01
3.16E+01
i/1
3.10E+00
3.10E+00
5.24E+00
1/1
2.20E+00
2.20E+00
5.24E-HX)
NO
-
-
-
4/4
2.28E+03
2.28E+03
5.70E+02
5.70E+02
—
1.50E+04
8/8
2.21E+04
1.82E+04
2.00E+04
2/2
1.34E+03
1.34E+03
1.00E+03
-
-
-
1.00E+03
NO, essential nutrient
Lead.
—
—
—
3/4
2.20E+00
2.20E+00
5.50E-01
5.50E-01
-
1.20E+02
8/8
1.56E+01
1.26E+01
3-58E+01
2/2
1.60E+00
1.60E+00
1.17E+00
-
-
-
1.17E+00
YES
-
-
-
4/4
1.76E+03
1.76E+03
4.40E+02
4.40E+02
—
NA
8/8
7.19E+03
6.05E+03
NA
2/2
3.22E+04
3.22E+04
3^4E+03
2/2
3.21E+04
3.21 E+04
3-24E+03
NO, essratial nutrient
Manganese
-
-
-
4/4
1.24E+02
1.24E+02
3.10E+01
3.10E+01
—
2.20E+02
8/8
S.42E+02
4.37E+02
4.60E+02
2/2
1.14E+02
1.14E+02
1.20E+02
2/2
5.40E+00
5.40E+00
1.20E+02
YES
Mercnry
-
-
-
4/4
9.20E-01
9.20E-01
2.30E-01
2.30E-01
—
1.00E-01
8/8
1.00 E-01
7.47E-02
1.80E-01
-
-
-
1.30E+00
-
-
-
1.30E-HX)
NO
Nickel
—
—
—
4/4
2.00E+00
2.00E+00
5.00E-01
5.00E-01
-
3.80E+01
8/8
1.35E+01
1.09 E-01
2.27E+01
2/2
1.80E+00
1.80E+00
2.89E+01
1/2
1.10E+00
1.10E+00
2.89E+01
NO
Potassium
-
-
-
4/4
1.28E+04
1.28E+04
3.20E+03
3.20E+03
—
NA
8/8
4.90E+03
3.91 E+03
NA
2/2
7.02E+03
7.02E+03
NA
2/2
6.99E+03
6.99E+03
NA
NO, essratial nutrient
Selenium
-
-
-
4/4
9.20E-01
9.20E-01
2.30E-01
2.30E-01
—
5.20E-01
-
-
NA
2/2
1.70E+00
1.70E+00
5.00E+00
2/2
1.70E+00
1.70E+00
J.OOE+OO
NO
SftHimn
-
-
-
4/4
5.60E+03
5.60E+03
1.40E+03
1.40E+03
—
NA
5/8
6.80E+02
S.61E+02
NA
2/2
1.67E+0S
1.67E+05
NA
2/2
1.6SE+05
1.65E+OS
NA
NO, essential nutrient
Vanadium
—
—
—
4/4
6.40E+00
6.40E+00
1.60E+00
1.60E+00
-
2.00E+00
8/8
Z57E+01
Z15E+01
NA
2/2
1.06E+01
1.06E+01
2.00E+01
2/2
9.40E+00
9.40E+00
2.00E+01
YES
Zinc
-
-
-
4/4
4.00E+02
4.00E+02
1.00E+02
1.00E+02
-
U0E+02
8/8
6.20E+01
4.96E+01
U1E+02
2/2
5.60E+00
5.60E+00
6J7E+01
2/2
1.40E+00
1.40E+00
6J7E+01
NO
PCBS
Aroclw-1254
m
2.64E-01
2.64E-01
6.60E-02
6.60E-02
11/12
4.40E+00
3.03E+00
1.10E+00
7.58E-01
-
4.00E+01
21/24
1.10E-01
S.10E-02
6.00E-02
-
-
-
1.40E-02
—
1.40E-02
YES
Total PCB Ccngenera
2/2
6.40 E-01
6.40 E-01
1.60 E-01
1.60 E-01
3/3
2.04E+01
2.04E+01
5.10E+00
5.10E+00
—
4.Q0E+01
2/2
3.50E-02
3.50E-02
5.98E-02
-
-
-
U0E-02
—
1.40E-02
YES, main COPC
Total PCB Aroclcrs
7/7
2.64E-01
2.64E-01
6.60E-02
6.60E-02
11/11
4.40E+00
2.80E+00
l.lOE+OO
6.99E-01
-
4.00E+01
21/24
l.lOE-Ol
S.68E-02
5.98E-02
-
-
-
U0E-02
-
1.40E-02
YES
PESTICIDES
DDTr
-
-
-
4/4
7.68E-01
7.68E-01
1.92E-01
1.92E-01
-
NA
10/10
1.87E-02
1.20E-02
5.28E-03
1/1
7.40E-02
7.40E-02
NA
—
NA
YES
deha-BHC
—
—
—
-
-
-
-
-
—
NA
1/10
9.80E-04
9.80E-O4
3.00E-03
-
-
-
1.41E+02
—
1.41E+02
NO
Fndrin
—
—
—
4/4
3.16E-01
3.16E-01
7.90E-02
7.90E-02
—
NA
1/10
1.50E-03
l.SOE-03
2.22E-03
-
-
-
2.00E-03
—
2.00E-03
NO
guiTTTn a-Chlaidaiie
—
—
—
4/4
1.00 E-01
1.00E-01
2.50E-02
2.50E-02
—
NA
9/10
4.40E-03
2.42E-03
3.24E-03
-
-
-
4.00E-03
—
4.00E-03
YES
Heptachlor epoxide
-
-
-
4/4
1.08E-02
1.08E-02
2.70E-03
2.70E-03
-
NA
3/10
1.50E-03
1.50E-03
2.47E-03
-
-
3.80E-03
-
3.80E-03
NO
Note:
95UCLM: 95 pncait upper confidence limit on the mean
COPC: Chemical of potential concern
Selection of Chsmcals ofPotential Concern: if an analyte exceeds the screening criteria in any media or no screening it available, the analyte is retained as a COPC
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
000803
Record of Decision
-------
Selection of Chemicals of Potential Cmcem
for Exposure Area 5: Lined Canals, Reservoirs, and Soil
Benthos Tissue
Fish Tissue
Surface Soil
Sediment
Surface Water (Total)
Surface Water (Dissolved)
Selection of
Chenacals of
Potential Concern
Selection of Chemicals
of Potential Concern
Frequency
Maximum
(mg/kg)
95UCLM
(mg/kg)
Frequency
Maximum
(mg/kg dry
wt)
95UCLM
(mg/kg dry
wt)
Maximum
(mg/kg wet
wt)
95UCLM
(mg/kg wet
wt)
Frequency
Maximum
(mg/kg)
95UCLM
(mg/kg)
Screening Criteria
(mg/kg)
Frequency
Maximum
(mg/kg)
95UCLM
(mg/kg)
Screening
Criteria
(mg/kg)
Frequency
Maximum
(W5/L)
95UCLM
0»b/l)
Screening
Criteria
(fg/L)
Frequency
Maximum
W-)
95UCLM
(W5/L)
Screening
Criteria
W-)
Terrestrial Habitats
Aquatic Habitats
Metals
Aluminum
-
-
-
2/2
1.56E+01
1.56E+01
3.90E+C0
3.90E+00
58/58
2.77E+04
2.08E+04
3.00E+04
18/18
6.74E+C4
2.67E+04
NA
11/12
1.86E+03
1.16E+03
8.70E+01
2/12
2.02E+03
2.02E+03
8.70E+C1
NO
YES
Arsenic
—
—
—
—
—
—
—
—
58/58
7.60E+C0
5.62E+00
1.80E+01
18/18
2.51E+C1
7.65E+00
9.79E+C0
12/12
4.90E+00
4.90E+00
1.50E+02
12/12
4.80E+00
4.50E+00
1.50E+02
NO
YES
Barium
—
—
—
2/2
2.76B+01
2.76B+01
6.90E+00
6 9011+00
58/58
3.59E+02
1.91E+02
3.30E+02
18/18
2.14E+02
1.77E+02
NA
12/12
1.54E+02
1 39E+02
1 60E+04
12/12
1.47E+02
1.27B+02
1.60E+04
YES
YES
Bei^lium
—
—
—
—
—
—
—
—
58/58
1.20E+00
9.00E-01
1.00E+01
6/18
1.00E+00
8.95E-01
NA
—
5.30E+00
—
5.30E+C0
NO
YES
Cadmium
-
-
-
1/2
8.00E-02
8.00E-02
2.00E-02
2.00E-02
30/58
6.40E-01
4.88E-01
3.20E+01
18/18
5.10B-01
4.25E-01
9.90E-01
-
-
-
1.50E-01
-
-
-
1.50E-01
NO
NO
Calcium
—
—
—
2/2
7.60E+04
7.60E+04
1.90E+04
19011+04
58/58
1.34E+05
1.01E+05
NA
18/18
2.11E+05
1 24B+05
NA
12/12
19011+05
10611+05
NA
12/12
9.58E+04
8.01E+04
NA
NO, essential nutrient
NO, essential nutrient
Chmrnium
-
-
-
2/2
1.04E+00
1.04E+00
2.60E-01
2.60E-01
58/58
1.61E+C1
1.21E+01
4.00E-01
18/18
1.52E+C1
1.21E+01
4.34E+01
4/12
7.60E-01
7.60E-01
4.20E+01
4/12
3.50E-01
3.47E-01
4.20E+01
YES
NO
Cobalt
—
—
—
1/2
2.84E-01
2.84E-01
7.10E-02
7.10E-02
58/58
7.40B+00
6.20E+00
1.30E+01
18/18
6.60E+00
5.73B+00
5.00E+01
—
—
—
1.50E+03
—
—
—
1.50E+03
NO
NO
Copper
-
-
-
2/2
3.80E+00
3.80E+00
9.50E-01
9.50E-01
58/58
1.88E+C1
1.20EI01
7.00E+01
18/18
7.59E+03
4.62E+03
3.16E+01
12/12
2.64E 102
1.19E102
5.24E+00
3/12
2.50E+02
2.50E+02
5.24E+00
NO
YES
Iran
-
-
-
2/2
9.60E+01
9.60E+01
2.40B+01
2.40E+01
58/58
6.02E+04
2.18E+04
1.50E+04
18/18
2.34E+04
1.92B+04
2.00E+04
11/12
1.55B+03
1.01E+03
10011+03
2/12
1.83E+03
1.83E+03
1.00E+03
NO, essential nutrient
NO, essential nutrient
Leal
—
—
—
2/2
2.80E-01
2.80E-01
7.00E-02
7.00E-02
58/58
7.42E+01
1.88E+01
1.20E+02
18/18
4.09E+01
1.84E+01
3.58E+01
10/12
2 0011+00
1.35B+00
1.17E+00
1/12
2.20E+00
2.20E+00
1.17E+00
NO
YES
Magnesium
-
-
-
2/2
2.16E+03
2.16E+03
5.40E+02
5.40E+02
58/58
1.04E+04
7.14E+03
NA
18/18
9.00E+03
7.13E+03
NA
12/12
5.63E+04
3.73E+04
3.24E+03
12/12
3.34E+04
3.19E+04
3.24E+03
NO, essential nutrient
NO, essential nutrient
Manganese
—
—
—
2/2
3.16B+01
3.16B+01
7.90E+00
7 9011+00
58/58
7.79E+02
3 9611+02
2.20E+02
18/18
5.09E+02
4.40E+02
4.60E+02
12/12
1.15B+02
8.82E+01
1 20E+02
6/12
1.31E+02
4.99E+01
1.20E+02
YES
YES
Mercury
—
—
—
2/2
3.60E-01
3.60E-01
9.00E-02
9.00E-02
57/58
9.40E-02
5.29E-02
1.00E-01
17/18
6.00E-02
4.33E-02
1.80E-01
—
—
—
1.30E+00
—
—
—
1.30E+00
NO
NO
Nickel
-
-
-
2/2
5.20E-01
5.20E-01
1.30E-01
1.30E-01
58/58
1.70E+C1
1.33E+01
3.80E+01
18/18
1.45E+01
1.18E+01
2.27E+01
11/12
2.30E+00
1.79E+00
2.89E+01
7/12
2.30E+00
1.42EIOO
2.89E+01
NO
NO
Potassium
—
—
—
2/2
1.04E+04
1.04E+04
2.60E+03
2.60E+03
58/58
6.27E+03
5.19E+03
NA
18/18
6.03E+03
4.70E+03
NA
12/12
1.22B+04
8.28E+03
NA
12/12
7.63B+03
7.14E+03
NA
NO, essential nutrient
NO, essential nutrient
Selenium
-
-
-
2/2
1.12E+00
1.12E+00
2.80E-01
2.80E-01
12/58
2.60E-01
1.46E-01
5.20E-01
13/18
4.80E-01
3.57E-01
NA
12/12
1.80E+00
1.22E+00
5.00E+00
7/12
1.50E+00
1.51E+00
5.00E+00
NO
YES
Sodium
—
—
—
2/2
4.40E+03
4 4011+03
1.10E+03
1.10E+03
35/58
1.79E+04
3.20E+03
NA
16/18
1.18E+03
8.4411+02
NA
12/12
3.34B+05
2.05E+05
NA
12/12
1.77E+05
1.67E+05
NA
NO, essential nutrient
NO, essential nutrient
Vanadium
-
-
-
2/2
2.12E+00
2.12E+00
5.30E-01
5.30E-01
58/58
3.14E+C1
2.33E+01
2.00E+00
18/18
3.58E+01
2.47E+01
NA
12/12
1.05E+01
1.00E+01
2.00E+01
12/12
1.10E+01
9.16E+00
2.00E+01
YES
YES
Zinc
-
-
-
212
3.20E+02
3.20E+02
8.00B+01
8.00B+01
58/58
1.60B+02
6.03B+01
1.20E+02
18/18
6.95E+01
5.33E+01
1.21E+02
12/12
8.10B+00
5.43E+00
6.57E+01
8/12
1.61E+01
5.73E+00
6.57E+01
YES
NO
peas
Aroclor-1016
-
-
—
—
-
—
-
-
1/70
3.40E-03
3.40E-03
4.00E+01
-
-
-
7.00E-03
-
-
-
1.40E-02
-
-
-
1.40E-02
YES, main COPC
NO
Araclor-1254
-
-
-
8/28
1 1611+00
4.80E-01
2.90E-01
1.20E-01
3/70
1.10E-02
1.10E-02
4.00E+01
15/33
2.30E-02
6.08E-03
6.00E-02
-
-
-
1.40E-02
-
-
-
1.40E-02
YES, main COPC
YES, main COPC
Araclor-1260
-
-
-
-
-
-
-
-
27/70
1.00E-02
2.67E-03
4.00E+01
4/33
2.80E-03
2.20E-03
5.00E-03
-
-
-
1.40E-02
-
-
-
1.40E-02
YES, main COPC
YES, main COPC
Total PCB Congeners
-
-
-
3/3
4.79E-01
4.79E-01
1.20E-01
1.20E-01
24/24
4.50E-02
1.02E-02
4.00E+01
10/10
2.10E-02
1.32E-02
5.98E-02
6/6
1.10E-02
1.10E-02
1.40E-02
1.40E-02
YES, main COPC
YES, main COPC
Total PCB Aioclon
-
-
-
8/8
1.16B+00
9.56E-01
2.90E-01
2.39E-01
28/28
1.76B-02
6.23E-03
4.00B+01
18/33
2.30E-02
1.33E-02
5.98E-02
-
-
-
1.40E-02
-
-
-
1.40E-02
YES, main COPC
YES, main COPC
PESTICIDES
DDTr
-
-
-
212
2.27E-01
2.27E-01
5.67E-02
5.67E-02
47/58
8.14E-02
2.10E-02
NA
16/19
9.67E-02
4.51E-02
5.28E-03
1/12
3.10E-02
3.10E-02
NA
-
NA
YES
YES
Aldrin
_
_
_
1/2
4.00E-04
4.00E-04
1.00E-04
1.00E-04
_
_
_
NA
1/19
6.50E-04
6.50E-04
2.00E-03
_
_
_
3.00E-01
_
_
_
3.00E-01
NO
NO
alpha-BHC
_
_
_
_
_
_
_
_
_
_
_
NA
2/19
6.70E-04
6.70E-04
6.00E-03
_
_
_
7.40E+01
_
_
_
7.40E+C1
NO
NO
alpha-CMordane
_
_
_
2/2
6.80E-03
6.80E-03
1.70E-03
1.70E-03
1/58
2.30E-03
2.30E-03
NA
3/19
1.30E-03
1.30E-03
3.24E-03
_
_
_
4.00E-03
_
_
_
4.00E-03
YES
NO
ddta-BHC
_
_
_
-
_
_
_
_
_
_
_
NA
2/19
3.00E-03
3.00E-03
3.00E-03
1/12
2.80E-02
2.80E-02
1.41E+02
1.41E+02
NO
YES
Dieldrin
_
_
_
_
_
_
_
_
2/58
1.40E-02
1.40E-02
NA
1/19
7.50E-03
7.50E-03
1.90E-03
_
_
_
2.00E-03
_
_
_
2.00E-03
YES
YES
Endosulian 1
_
_
_
_
_
_
_
_
1/58
7.50E-04
7.50E-04
NA
_
_
NA
_
_
_
5.60E-02
_
_
_
5.60E-02
YES
NO
Endosulian n
_
_
_
_
_
_
_
_
5/58
1.70E-02
2.36E-03
NA
2/19
6.00E-03
6.00E-03
NA
_
_
_
5.60E-02
_
_
_
5.60E-02
YES
YES
Endosulian sulfite
_
_
_
212
2.12E-03
2.12E-03
5.30E-04
5.30E-04
2/58
1.30E-02
1.30E-02
NA
1/19
1.70E-03
1.70E-03
NA
_
_
_
5.60E-02
_
_
_
5.60E-02
YES
YES
Frdrtn
_
_
_
2/2
3.64E-02
3.64E-02
9.10E-03
9.10E-03
3/58
6.90E-03
6.90E-03
NA
1/19
1.30E-03
1.30E-03
2.22E-03
_
_
_
2.00E-03
_
_
_
2.00E-03
YES
NO
Frdrtn aldehyde
_
_
_
2/2
3.56E-03
3.56E-03
8.90E-04
8.90E-04
10/58
3.50E-02
4.14E-03
NA
3/19
5.60E-03
5.60E-03
NA
_
_
_
1.21E+03
_
_
_
1.21E+03
YES
YES
Endrin ketone
_
_
_
2/2
8.00E-03
8.00E-03
2.00E-03
2.00E-03
1/58
2.10E-03
2.10E-03
NA
1/19
2.10E-02
2.10E-02
NA
_
_
_
NA
_
_
_
NA
YES
YES
gamma-BHC (Lindane)
_
_
_
1/2
3.00E-04
3.00E-04
7.50E-05
7.50E-05
_
_
_
NA
1/19
9.40E-04
9.40E-04
2.37E-03
_
_
_
8.00E-02
_
_
_
8.00E-02
NO
NO
gamma-Chlardane
_
_
_
1/2
2.36E-02
2.36E-02
5.90E-03
5.90E-03
3/58
1.40E-03
1.40E-03
NA
7/19
2.90E-03
1.98E-03
3.24E-03
_
_
_
4.00E-03
_
_
_
4.00E-03
YES
NO
HcptachlOT
-
-
-
-
-
-
-
-
-
-
-
NA
1/19
3.90E-03
3.90E-03
NA
-
-
-
4.00E-03
-
-
-
4.00E-03
NO
YES
I teptachlor epoxide
-
-
-
212
1.48E-03
1.48E-03
3.70B-04
3.70E-04
2/58
1.10E-03
1.10E-03
NA
6/19
1.80E-03
1.53E-03
2.47B-03
-
-
-
3.80E-03
-
-
-
3.80E-03
YES
NO
Methoxychlor
-
-
-
2/2
2.36E-02
2.36E-02
5.90E-03
5.90E-03
2/58
1.10E-02
1.10E-02
NA
1/19
3.00E-02
3.00E-02
NA
-
-
-
3.00E-02
-
-
-
3.00E-02
YES
YES
Tosaphene
-
-
-
-
-
-
-
-
2/58
5.60E-01
5.60E-01
NA
-
-
-
1-00E-04
-
-
-
2.00E-04
-
-
-
2.00B-04
YES
NO
PAIh
Total LMW PAHs
-
-
-
-
-
-
-
-
3/58
1.30E-01
1.30E-01
2.90E+01
2/19
2.77E+01
2.77E+01
5.52E-01
-
-
-
NA
-
-
-
NA
NO
YES
Total HMWPAHs
-
-
-
-
-
-
-
-
3/58
1.30E+00
1.30E+00
1.80E+C1
3/19
2.38E+02
2.38E+02
1.70E+00
-
-
-
NA
-
-
-
NA
NO
YES
svocs
Benzaldehyde
-
-
-
2/2
2.48E-01
2.48E-01
6.20E-02
6.20E-02
-
-
-
NA
-
-
-
NA
1/12
2.00E+00
2.00E+00
NA
NA
NO
YES
Bi s (2-ethylhc xyijphthfllate
-
-
-
-
-
-
-
-
22/58
5.20E+00
4.75E-01
NA
5/19
8.10E+00
3.41E+00
1.80E-01
1/12
3.10E+00
3.10E+00
3.00E+02
-
3.00E+02
YES
YES
ButylbenzylphthalBte
-
-
-
-
-
-
-
-
1/58
4.70B-01
4.70E-01
NA
1/19
9.90E-01
9.90E-01
NA
-
-
-
9.30B+01
-
-
-
9.30B+01
YES
YES
Caprolactam
-
-
-
-
-
-
-
-
-
-
-
NA
-
-
-
NA
1/12
3.10E+00
3.10E+00
NA
-
NA
NO
YES
Caibazole
-
-
-
-
-
-
-
-
-
-
-
NA
1/19
2.40E+00
2.40E+00
NA
-
-
-
NA
-
-
-
NA
NO
YES
Dibenzo&ran
-
-
-
-
-
-
-
-
-
-
-
NA
1/19
3.50E-01
3.50E-01
NA
-
-
-
9.40B+01
-
-
-
9.40E+01
NO
YES
Di-n-butyl phthalate
-
-
-
-
-
-
-
-
3/58
1-OOB-Ol
l-OOE-Ol
2.00B+02
-
-
-
NA
-
-
-
7.00B+00
-
-
-
7-00E+00
NO
NO
vocs
Acetone
-
-
-
-
-
-
-
-
7/19
1.71E-02
1.35E-02
NA
-
-
-
6.00E+01
1/6
4.80E+00
4.80E+00
1.01E+05
1.01E+05
YES
NO
Bromodichloromethane
_
_
_
_
_
_
_
_
_
_
_
NA
_
_
_
2.46E+C0
1/6
3.40E+00
3.40E+00
2.16E+03
-
2.16E+03
NO
NO
Bromofbrm
_
_
_
_
_
_
_
_
_
_
_
NA
_
_
_
NA
1/6
3.60E+00
3.60E+00
1.49E+02
-
1.49E+02
NO
NO
Chloroform
_
_
_
_
_
_
_
_
_
_
_
NA
_
_
_
9.40E-01
1/6
2.10E+00
2.10E+00
8.90E+02
8.90E+02
NO
NO
DibromocMoromethane
_
_
_
_
_
_
_
_
_
_
_
NA
_
_
_
1.60E-01
1/6
4.20E+00
4.20E+00
1.29E+02
1.29E+02
NO
NO
Methylene chloride
-
-
-
-
4/19
3.60E-03
3.52E-03
NA
-
7.75E+00
-
1.10E+04
-
1.10E+04
YES
NO
Toluene
-
-
-
-
-
-
2.00E+02
1/9
4.70E-03
4.70E-03
2.88E+00
-
1.45B+03
-
1.45E+03
NO
NO
Note:
iceeds the screening criteria in any media or no screening is available, the analyte is retained as a COPC
No data available
COPC: Chemical of potential concern
Selection of Chemicals of Potential Concern: if an analyte e
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas Record of Decision
000804
-------
Appendix C
Costs for Alternative 6, Replace Siphon and
Dredging of Canal Sediment with Off-Site Disposal
000805
-------
Alternative Contporwstf Sl-B; Pane i of 2
TECHNOLOGY
LOCATION
MEDIUM
Estimated Cost to Implement
$8,100,000
Replace Siphon
Dorian Reservoir «nd Canal System
Siphon
Construction Time:
4
nwnlJif
Alternative Component Sl-B
Donna, TX
Op era lien Time:
.
vcart
Po.il Remcdiutifin MonlloHaf
-
yemn
Quantiliri.
Cwt Breakdown fit available)
Combined limit
Coib
Description
Data Source
(Moans' or Other)
QuBPttry
Amount
Quantity
UntL
Labor
Unit Cost
labor
Total Cost
Equipment
Unit Cost
Equipment
Total Cost
Material
Unit Cflst
Matenol
Total Cost
Unit Cost
Option
Total Co*t
REMEDIAL ACTION
TOTAL CAPITAL COST
{totals rounded to nearest thousand)
$8,100,00(1
Construction Activities
55,185,422
Temporary Facilities and Site Maintenance
Command facility 40' combo with 15" office
Mobile Mini, fac-
4
month
i
$
s
$
S
4
566.00
42.024
Office equipment rental average
0152 13400100
4
month
s
s
4
$
219
4 It 77
s
itni
Lend lease
U5DA
4
month
$
s
$
i
4
33.46
SI 34
Command facility tncbilfczatton'demobi li/atton
Mobile Mint, Inc.
lump 5i im
$
s
$
J
4
s
1,914.00
$1,914
Clearing St grubbing, light tree*, to ft" diameter
3111 10I0002C
I
acre
s
2,206
J
2.706
5
1,807
S 1,807
%
?
%
HOW
j Rough gmde. 20, J 00-25,(10(1 S F
3122 1320 0210
1
ea
s
S7G
4
576
4
550
4 550
S
4
s
$1,127
Temporary, road*, gravel fill, 4" gravel depth
0155 23500050
2.500
SY
*
2
5J2ii
S I
S 1.385
*
A
5 10,145
4
516,757
Fencing
United Site Services
4
month
s
S
4
s
s
s
S
550-00
$2,200
Oawtatjjr
United Rentals
4
month
X
s
s
s
4
3.922.60
415,690
Lightini;
United Rentals;
4
month
s
S
4
$
S
1.663 20
$6,653
Toilet, portable cheiniml (2 toilets)
0154 3340 MID
4
month
1
s
$
s
%
S
427.90
$1,712
Rubbish hardline, durnpsisr, JO CV, J Ion capacity, one dump per week
024 J 19190700
16
weeks
$
s
4
% ill
4 8,180
4
$8,1 SO
Sit* weonty (24 injurs a dayy (2 guards 1
0156 32500100
5.760
Kit
1
49.58
I
285,565
s
%
S
5285,565
Excavation, lR.srtU*tton and Backfill
Pre- and post-construction topographical survey
022) UO9OI0O
3,67
acre
1
4.240
s
15,575
4
158
S 579
t 132
4 483
4
$16,636
Par diem
GSA +1 as
S4
day
5
s
4
s
$
4
S
1,992,00
5167^28
Clearing brush by hand
3113 13 to 0\80
1.94
acre
5
2.857
%
5,2-tt.
5
S
5
4
45.246
Erosion control, sill fence, inBall and maintain. remove, 5' high
3125 1416 1000
5,000
LF
5 1
s
4351
i
0,14
S 692
$ 1
4 2,982
S
53,026
Rent and operate walo truck, off highway, 6,1*00 gallon capacity
0154 3340 &950
12
wsek
*
I
s
s
4
9,630.10
S115,561
108" riinmetct pipe, prestressed concrete
Layoe ChristenKO Company
1,600
LF
i
s
4
4
S
770,00
$1)232,000
Excavation, installation, backfill, compaction Labor
Layne Chnstcnseo Company
1,600
LF
5
5
5
4
220.00
5352,000
Engineering oversight
Professional est
34
day
1
768
J
64.512
S
S
S
S
564,512
Bjpmi Arroyo Colorado
Per diem
GSA-Tax
21
day
1
s
5
S
s
s
1,992,00
541,832
Cofferdam including mgbil Ration and temporary sheeting, shore driven
3152 1610 0020/profeHitHia! esttmme
6,000
sr
i
7
5
44,732
s
9
S 51,378
S 36,042
4 216,250
4
5312,360
Dewaicring systems, drainage Imvch 2' wide, 3' deep with backbttc loader
3123 1920 m (W
140
CV
5
6
s
831
4
3
5 410
S
SU41
Pumping 8 tir,. 2ft LF suction 100 LF discharge, 6 inch centrifbgiil {.2 pump)
3123 1920 1100
21
day
5
633
5
13,23)9
5
767
S 16,101
s
4
529,390
Excavating bypass, 1 CV hydraulic excavator
3123 1613 0120
2,400
8CV
5
2
S
4,£94
4
2
S 5,266
s
S
510,160
Sill curtain {I Ofi'iT)
Granite Environmental, (nc
3
ea
s
5
S
4
2.427.69
57,283
Sampling aratysis - PCS as Araclori
TejtAmericjj, Inc.
20
ea
5
s
4
4
S
IK0.40
53,608
Professional est
1
ifl
s
5
5
5
4
2.200.00
52,200
j Backfill, 2-1/2 CY end loader, 30(1* W
3123 2317 0190
3,000
LCY
5 1
S
3,156
4
3
S 10,193
4
S
513^149
Rough grade 75,1 OO- [00,000 SF
3122 1320 0280
|
ea
S
2J32
S
2^532
5
2.131
S 2,131
4
4
54,363
Modified Canal Segment!
Per diem
GSA + Tax
35
days
1
I
s
J
S
2,490.00
$87,150
Rough grade 75, ttKM 00.000 SF
3122 1320 0280
2
ea
5
2,232
s
4,464
4
2,131
4 4,262
J
4
48,725
I-jccavation. fiydranltc, crawler rad, 1-1/2 CY
1123 1642 0250
$.000
0CY
4
0J2
$
4,091
5
1.11
S 5.53H
s
4
$9,630
Selective demolition, concrete
030505100050
800
CY
*
49.54
s
39,631
4
10.30
S 8,239
4
4
447,870
( Cast-in place retaining watts, wf vertical tact, 33 deg embankment, 10* high
3232 1310 2600
600
LF
s
m. si
s
341,712
4
73.36
S 44,017
i 402
S 241,491
4
5627,221
Slip form concrete canal lining, lanreinforecd, {Tthiek
3213 1328 0120
3,667
SY
5
0.78
s
2.S57
4
0.K7
S 3,202
$ 37
4 137,229
4
5I43,2S9
Cofferdam at siphon entrance and exit
Lincoln Park F3?
100
LF
4
4
5
4
325.23
432,523
Bypass pumps, 375 HP djewJ. 16 pumps)
Baker Corp/0131 1320 0160
2
wesk
S
s
4
4
49,055 SO
598,111
Pump Awl costs
Baker Corp
14
day
5
5
$
4
7,603.20
5106,445
Knife Gate, htwdwheel opeator, 20" diameter
3520 1669 0170
6
ea
i
39*5.79
S
2,381
4
3BS.41
4 2,330
$ 13^71
4 140,223
4
5*4,934
Prestrussed concrete pipe, 150 PSL E2" diameter
3311 1310 3000
600
LF
4
8.65
S
5,190
5
4,21
S 2,524
S 64
4 311,508
4
546,223
Weir replacement (flow control gate)
Layne Christen sen Company
1
ea
1
s
4
S
4
385,000.00
$385,000
Donna Reservoir nnd Canal System
Italian, Hidalgo County, 7 e»:as
000806
-------
Alternative Component Sl-B; Pant 2 of 2
TECHNOLOGY
LOCATION
MEDIUM
Estimated Cost to Implement
$8,100,000
Replace Siphon
Alternative Cumponent SI-B
Donna Reservoir «nd Canal System
Donna* TX
Siphon
Construction Time:
4
month*
Operation Time:
.
Stars
Poll Remediation Monitorial
-
jean
Quantities
Cact Breakdown (if available)
Combined linit
Co»l*
Description
Data Skjurce
(Means' or Other!
Quantity
Amount
Quantity
Unit
Lftbtw
Unit Cost
labor
Total Cost
Equipment
Unit Cost
Equipment
Total Cost
Material
Unit Cos*
Ma tent1.1
Total Cost
Unit Cost
Option
Tola! Cost
F.siitlni; Siphon Sealing
Total cost to complete j inquip Associates, Inc
I
ea
5
S
S
S
S
S
S 7711,1)00,00
5770,000
Site Restoration
i Rough grade 75,100-100.000 SF
3122 1320 0280
1
ea
S 2^32
% 2J32
$ 2,131
$ 3,131
S
$
s
$4,363
Sccdinji. hydro of all seeding, with mulch aacf fertilizer
3292 1914 5400
300
MSF
3 15
$ 4,368
$ 9
5 2,709
S 44
5 13,135
s
120,302
Mobilization and Demobilization
£259,053
1 5% |of Total Costs of Site Wort
$5,183,060
$259,051
SV5
tern Contingency
SI .360,(128
25% |of Total Construction Activities
45,440,113
$1,360,028
ProfMsionai/lecbnical Services3
SI aw,027
5%
of Construct i.gu +¦ Contingency for Project Management
S 6,800,141
$340,007
of Construction t Contingency for Remedial Design
£ 6,900,141
$544,01 J
6%
of Construction + Contingency for Construction Management
S 6,800,141
«0K,(HJS
OPERATION AND MAINTENANCE
ANNUAL 0& M COST S
LIFETIME O&M (NPV) S
NO LONG TERM QAM REQUIRED
LONG TERM MONITORING
ANNUAL LTM COST
LIFETIME LTM (NPV)
NO LONG TERM MONITOR TNG REQUIRED
TOTAL ESTIMATED NPV TECHNOIXJGV COST (Capital + lifetime O&M + Potl Remediation Monitoring)
£8,10(1,001)
Assumptions:
Gtuetnl
Wedding eosdiiioo m Snfeiy Level;
Weighted Average of city cost tadejt
Costs arc loaded with mnik-tip
Inflation
Sales Tax
(Labor pfoductiviryj W2% \:
;fnoi applicable for cost3 derived from vendor quotes).
~|tor 2 yews
L
Equipment productivity [
13% | for4 years I 34%
for 10 year*
Density of Soil
1.6
lon/CV
Workers work week censisu of
6
d*V#/weele | * _Jrtw
Loose cubic yard to in-plfcce cubic yanl rstk»
1.25
LCY/BCY
1
mq^dkratiuo'dernobiltratkins per eiccaviitor
| SfcM
_j per dieru per ng
Workers work week: consists of
6
cLuY* ''week | 1 |riBf
1
rnnbiiiratinn/iicmobiliMtions pec excavator
| S6M
per diem pernj{
Standard work day
12
hn
Approximate hflttriy wags Field Engineer
SlfflO.OQ
BC Y
In-ptace cubic yaJil
B*'
Gallon
LF
L mew too:
CY
Cubic yard
hrs
Hours
MSF
thousand square feet
ea
l-atrh
HP
burse power
O&M
Operation and maintenance
tc/v
Embankment cubic yards.
HAS
Health and Safety
SF
Square foot
ft
Foot
LCY
Loose cubic yard
SY
Square yard
Source is The Gordian Group, R% Means Online (2016), McAUcti, TX, unions otherwise cited
Source' "Lincoln Park/Milwaukee River Channel Sediments Site, Pba® It feasibility Study Remedial Design', KA Engineering (201.3}
Sourer of tActn: "A Guide io DcvcMinn,^ and Documenting f'twi Funtujcs During.die Feasibility Study," L'S r.PA (Jidy 2000)
Dorma Reservoir and Canal System
fi'irmn Hidalgo County, 7 oas
000807
-------
Alternative Component SE-A; Page I of 4
TECHNOLOGY
LOCATION
MEDIUM
Estimated Cost to Implement
$11,30ft,000
Dredging of Canal Sediment with OfF-Slte Disposal
Donna Reservoir and Canal System
Sediment
Construction Time:
5
months
Alternative Component SE-A
Donna. TX
Operation Time:
5
yean
Post Remediation Monitoring
20
years
Quantities
Cost Breakdown lif available!
Combined Unfl
Costs
Description
Data Source
(Means' or Other)
Quantity
Amount
Quantity
Unit
Labor
Unit Cost
Labor
Total Cost
Equipment
Unit Cost
Equipment
Total Cost
Material
Unit Cost
Material
Total Cost
Unit Cast
Option
Total Cost
REMEDIAL ACTION - CONSTRUCTION
TOTAL CAPITAL COST
(totals rounded to nearest thousand)
57,580,0(10
Construction Activities
S5y332,903
Temporary Facilities and Site Maintenance
Command facility 40' combo wfth 15' office
Mobile Mini, Inc
5
month
S
s
S
S
5
5
S
506,00
52,530
Office equipment rental average
0152 13400100
5
month
i
5
s
s
S 219
S
1,096
$
St,096
Land least
L1SDA
5
month
s
s
s
s
S
S
s
33.46
SI 67
Clearing & grubbing, heavy ticc^ K1 ' 2" diameter
3111 1010 0200
I
acre
s
3.139
5
3,139
s
2,589
5
2,5H9
s
5
s
55,729
Rough, grade 35,100-40,000 SF
312213200240
1
e»
s
893
s
893
s
858
5 S5B
5
$
$
$1,750
Temporary,mads, gravel fill. 4" grovel depth
0155 2350 0050
4.000
SY
s
7
s
8.365
S 1
S
2,215
S 4
S
16,231
S26,811
Fencing
United Site Services
5
month
s
$
s
s
5
S
5
687.50
53,438
Generator
Untied Rentals
5
month
$
s
s
s
5
s
%
3,922.60
SI9.613
Lighting
United Rentals
5
month
$
s
s
$
5
5
$
1.663.20
58,316
Toilet, portable chemical (2 toilets)
0154 33406410
5
month
s
s
s
s
S
S
%
427.90
52,140
Rubbish handling, dumps ter, 10 CY, 3 ton capacity, one dump per week
0241 19190700
21
weeks
s
s
s
1
S 511
S
10,736
s
510,736
Temporary bridge rental
Mabey
21
weeks
s
s
.
s
1
5
s
s
1,034
$21,714
Concrete caissons tor marine const, 80 to 150 ton capacity, 22" diameter, 10* deep
3163 2616 0400
120
VLF
%
63
$
7,561
s
26
s
3,166
$ 27
$
3,288
%
$14,015
Temporary bridge installation
0131 13200160
1
week
&
11,884
s
11,184
s
s
S
-
s
S! 1,884
Gravel foi road maintenance. 3" thick.
Stone and Soil, Inc
134,5*0
SF
s
s
$
s
i
s
s
0.41
$54,829
Gravel freight
Stone and Soil. Inc
62
load
$
$
$
s
s
%
5
220.00
$13,713
Excavittor diesel hydraulic crawler mourned 1-1/2 CY capacity
0154 33200200
6
week
5
4,066
s
24.396
s
3.110
s
IB ,657
S
s
$
S43.053
Site security (24 hours a day) (2 guards)
0156 32500100
7.200
hr
$
49.58
s
356.956
s
s
i
s
S
S336.956
Excavation
Per diem construction crew
GSA + Tax
100
day
i
s
s
s
S
s
.
S
1.328,00
S132,a(IO
Clearing brush by band
3113 13100100
3
acre
$
2,857
s
8,1125
s
s
s
$
%
58,825
Excavating, clamshell, 1 CY; for wet excavation
3123 1642 0550, 3123 16424200
19.979
BCY
$
2.91
s
58,128
s
4.78
s
95,543
s
s
-
5353,672
Excavator attachment, grapple
0154 3320 0345
15
weak
s
i
$
s
s
s
-
S
646.29
S9.65M
Front end louder, 4WD, 2.5-3,5 C V I45HP
0154 33204710/0131 1320 0160
15
week
$
1,981
$
29.711
$
s
s
s
s
1.392.88
$50,604
Rait truck, dump, 4 axle, 25 ton pay load
0154 3320 5310/0131 132(10160
15
week
s
1,981
s
29.711
$
s
5
s
.
V
1.654.74
$54,532
Silt curtain (1O01 X T)
Granite Environmental, Ene,
20
each
s
s
s
s
S
s
s
2.427.69
$48,554
Levee stabilization, loading and spreading, eotnmon earth, shovel. 1-1/2CY buck si
3123 2315 4010
554
BCY
s
0.71
s
396
s
1.27
s
702
5 39
s
21,783
s
S22.SH1
Ren! and operate water truck, otT hi ghway, 6.000 gallon capacity
01543340 6950
IS
week
s
s
s
s
S
&
&
9.630,10
$144,452
Engineering oversight
Professional est
50
day
&
MOO
$
60,000
s
1
$
s
s
$60,000
Disposal «r Sediment
Mobtli?ation'dem(3hiliaitioc> of water tight boxes
USA Environmental, LP
20
loud
$
s
s
s
5
£
s
1,100,00
S22,0tX>
Per diem truck drivers
GSA + Tax
79
day
$
s
$
s
5
s
s
1.660.00
$130,590
Transportation of sediment
USA Environmental, LP
1.573
load
$
5
s
s
s
5
s
550,00
SK65.354
Liners
USA Environmental, LP
1.573
load
$
s
s
1
i
S
s
33.00
$51,921
Box renal, 20 boxes
USA Environmental, LP
2,000
box days
$
s
s
s
5
S
5
13.20
$2o,4(XJ
Disposal of sediment, includes Stabilization
USA EnvifijnuteisLal, LP
28,321
ton
i
s
s
s
5
s
i
77.00
52,180,692
Washout of boxes
USA Environmental, LP
20
«
$
s
s
s
S
s
s
234.03
$4,681
Fractionation tutik. 20,000 gallon capacity; for sediment dewatering
Baker Corp, Inc,
100
day
s
s
$
s
S
s
s
4620
$4,620
Trash pump, for sediment dewaterinf,'
Sunbelt Rentals'0131 13200160
4
month
s
s
s
s
5
£
s
1,067.00
$4,2(58
Excavater diescl hydraulic crawler mounted. 1-1/2 CY
0154 33200200/0131 1320 0160
4
month
$
7,923
s
31,692
s
i
S
S
s
9.248.69
$68,687
Cement, Fori land, type l/IT, trucked In bulk, 94 lb bags
0305 13300250
42,180
ea
$
s
$
s
S 14
5
59(^589
s
S 596,589
Confirmation Sampling
Per diem
GSA + Tax
5
day
s
s
s
s
i
S
s
498,00
52.490
Forklift vanablo roach, 6,000 lbs
United Rentals
I
week
s
s
.
s
s
s
S
_
s
1^8990
51,990
17' Tracker boat with 4t)hp mater and trailer
Professions! est
i
week
$
t
35
s
i
S
$
uoo
$1,200
Dontiii Reservoir 4nd Canal System
Donna, Hidalgo County, Texas
000808
-------
Alternative Component SE-A; Page 2 of 4
TECHNOLOGY
LOCATION
MEDIUM
Estimated Cost to Implement
$11,300,000
Dredging of Canal -Sediment wftt* Off-Site Disposal
Alternative Component SE-A
Donna Reservoir and Canal System
Donna, TX
Sediment
Construction Time:
Operation Time:
Post Remediation Monitoring
5
months
5
years
20
years
Quantities
Coil Breakdown (if available)
Combined Unfl
Costs
Description
Dam Source
(Means' or Other)
Quantity
Amount
Quantity
Unit
Labor
Unit Cost
Labor
Total Cost
Equipment
Unit Cam
Equipment
Total Cost
Material
L! nit. CM
Material
Total Cost
Unit Cost
Option
Total Cost
Sampling labor (3 samplers)
Professional est
5
day
% 3,000
S 15.000
$
I
S
S
5
515,000
Sampling equipment, supplies, and shipping
Professional est
1
each
V
S
s
J
J
5
S 5,720
55,720
Sediment analysts - PCBs as Areclors
TcstAmeriea lac
50
efc
S
s
s
*
5
S
5 ISO
59,020
Reporting
Professional est
40
hr
SI 00
S 4,000
s
S
5
s
s
54,000
Engineering Com rah
Site
Sign, aluminum, reflcctorucd, 30" by 30" and 1C Bed posts, upright, bolted 11014 5320 0300/1014 5320 1 500
20
6*
S 28
% 561
$ 16
S 315
5 170,91
5 3.418
s
54,295
1
I
1
Rip-rap & rock lining
3137 13100200
413
SY
$ 49
S 20,402
S 15
$ 6,334
S 46
S 18,997
*
$45,733
Rough grade 50,tQ0'75,000 SF
3132 1320 0270
1
ca
S 1,610
5 1.610
5 1.537
S 1.537
S
S
s
53,14?
Mobilization and Demobilization
S266,645
5% lof Total Costs of Site Work
$5332,903
5266.645
System Contingency
St»399,100
25% lofTotoi Conjunction Activities
£5.596,400
S 1J99.100
Profession ill/Technical Services3
5577325
5%
of Construction (not including disposal) 4» Contingency far Project Management
S 3.038.551
5151,928
8%
of Construction (not including disposal) +- Contingency for Remedial Design
5 3.038,551
5243,084
6%
of Construction (not including disposal) + Contingency for Construction Management
5 3,038,551
5182313
REMEDIAL ACTION - FISH REMOVAL
ANNUAL COST S 733,000
TOTAL COST (NPV) S 3,010,000
Residual Contamination Removal
S5S8^91
Annual Oeitrufiihiaj; and Fish Removal (for 5 years)
Mobilization/demobilization
Professional est
2
ea
$
S
5
5
s
s
5 4,730.00
59.460
Fcrdicni
GSA + Tox
35
day
s
s
$
S
S - Is
S 830.00
529,050
Fork lift variable readi, 6,000 lbs
United Rentals
2
months
s
s
s
I
5
s
5 4,828.58
59,65 7
17' Tracker boat with 40hp motor and trailer
EA Engineering
35
dav
%
i
s
S
s
$
% 230
S 8,050
Regular IX" shocker for electro fishing
EA Engineering
35
day
5
s
$
£
s
5
J 260
59,100
Removal activities (5 person team)
Professional est
35
day
$ 6,000
S 210,000
s
S
s
s
$
5210.000
55 gallon steel drums
Dallas Steel Drums, fnc
500
ea
s
s
s
S
1
s
J 54
527,088
lla/jinJc«5 waste transportation fo disposal site
02812010 1Z60
500
mile
s
s
s
I
s
5
5 47
523.408
Hazardous waste pickup and disposal
0281 2010 1100
500
ca
*
5
s
s
s - 1$
$ 221
S 110,748
Low Water Removal Actions (for 5 years)
Mobtfeaticni'demob LliMioci
Profeiatonal eat
2
ea
s
s
s
s
s
$
S 4,730.00
59.460
Per diem
USA + Titt
10
day
5
5
s
s
i
5
S 664.00
56,640
Foddift variable reach. 6,000 lbs
United Rentals
2
week
5
s
s
s
s
$
$ 1.989.90
53,980
17' Tracker boat with 40hp motor and tra iler
EA Engineering
10
day
$
$
s
I
s
5
5 230
52,300
Cast Net
Buffs Super Pro Cast Net
1
ca
£
s
s
s
s
.1
S 264.00
5264
Seine Netting (43 lb lest)
Ths Fish Not Company
1 i
ea
i
s
s
$
s
s
5 211
5211
Removal activities <4 person team)
Professional est
10
day
5 4, BOO
5 1S,Q00
$
s
s
$
$
54g,000
55 gallon sted dninu
Dallas Sted Drums, Inc.
100
Ca
S
s
s
s
5
S
S 54
55,418
Hazardous waste transportation to disposal site
0281 20101260
500
mile
$
s
s
s
S
s
S 47
523,408
Hazardous Waste pickup and disposal
0281 20101100
100
ea
%
s
s
i
5
s
% 221
522,150
System Contingency
SI 39,598
| 25H (of Remedial Action - Fish Removals
1558,391
SI3i),597.76
Donna Reservoir and Canal System
Doom, ffhWgo County, Texas
000809
-------
Alternative Component SE-A; Page 3 of 4
TECHNOLOGY
LOCATION
MEDIUM
Estimated Cost to Implement
SI 1,300,000
Dredging of Canal -Sediment wftt* Off-Site Disposal
Alternative Component SE-A
Donna Reservoir and Canal System
Donna, TX
Sediment
Construct inn Time:
Operation Tunc:
Poal Remediation Monitoring
5
months
5
year?
20
years
Quantities
Cos! Breakdown lif available)
Combined Unit
Costs
Description
Dam Source
[Means' or Other)
Quantity
Amount
Quantity
Unit
Labor
Unit Cost
Labor
Total Cost
Equipment
Unit Cost
Equipment
Total Cost
Material
Unit Cost
Material
Total Cost
Unit Cost
Option
Total Cost
Profession iiLTeclinieal Services
S34,899
j 5% (of Remedial Action - Fish Removals - Contingency for Project Management
5 697,989
S 34,899
Lifetime Remedial Action - Fish Removals (Net Present Value)1
S 3.IMJ5,445
Annual Remedial Action - Fish Removals Net Present Valoe
S 3,005,445
5
Year j of Operation
7%
Discount Factor (per EPA guidance)
LONG TERM MONITORING, COMMUNITY INVOLVEMENT AND ENGINEERING CONTROLS
ANNUAL LTM COST 588,000
LIFETIME LTM (NPV) $700,000
Mo
nitaring, Sampling, Testing and Analysis - Fish
573,270
Pcwi Remediation Site MtwitortuR - FLih Tissue Sump ting (si years t, 2,3,4, S, 7, and
M ubiltoitjao/dt'jnobllt/alnin
Professional est
i
ea
5
S
S
S
S
5
5 8360.00
S&360
Per diem
GSA + Tux
5
days
$
5
S
S
5
s
5 664.00
53.320
Forklift vannblc reach. 6,000 Lbs
United Rentals
1
week
s
5
s
$
5
s
S 1,989.90
SI, 990
17' Tracker boat with 40hp motor and trailer
EA Engineering
5
day
s
$
s
I
S
s
5 255.96
51,280
Regular DC shocker for eleetrofishing
EA Engineering
5
day
s
5
s
s
5
s
5 255.96
S1.2I0
Sampling labor (4 varaplcre)
Professional est
5
day
& 4.B0O
S 24,000
s
$
S
s
5
S24.000
Sampling equipment, supplier and shipping
Professional est
1 |
ea
s
s
s
s
S
s
S 5.500.00
S5,500
Fid] tissue analysis - PCBi as Aroclore
Test America Laboratories
100
CO
s
s
s
5
i
s
S 235.40
523,540
Reporting
Professional est
40
hr
5 100
5 4,000
s
i
5
&
S
54,000
Monitoring. Sampling. Testing and Analysis - Sediment
SI 89,039
Post Remediation Site Monitoring - pediment Sampling (at year 4)
Mobilijaitiot^domobilization
Professional est
1
5
S
$
S
5
s
5 X .36000
SK360
Per dim
GSA + Tax
10
days
s
5
s
5
s
s
5 664.00
S6.640
Forkitft Variable reach. 6,000 lbs
Untied Rentals
2
week
5
5
s
$
s
s
5 1,98990
53,911(1
IT Tracker boat with 40hp motor and trailer
EA Engineering
10
day
s
5
s
S
5
s
$ 255.96
52,560
Sampling labor (4 samplers)
Professions] ess
10
day
5 4.800
S 48.000
s
s
5
s
S
548,000
Sampling equipment, supplies, and shipping
Professional est
1 [
ea
s
5
s
s
$ - Js
5 5.500.00
55,500
Sednnent analysis - PCB Congeners
Test America Laboratories
100
ea
5
5
$
s
s
s
5 1.100.00
5110.000
Reporting
Professional est
40
hr
5 100
S 4,000
s
s
5
5
5
54,000
Community Involvement
$9,846
MohitiaiEian/demofailizatioEi
Professional est
1
events
5
5
5
s
5
i
% 1,650.00
51,650
Per diem
GSA + Tbx
6
days
5
5
s
s
5
s
5 166.00
S996
Community uutteacfo event (2 representative-;}
Professional est
I
events
S 7,200
S 7,200
s
s
5
$
5
$7^00
Engineering Controls
51,074
Sign Replacement |l014 53200500/1014 5320 1500
5
ea
5 28
5 140
S 16
s 7y
5 170.91
5 §55
s
51,074
Professional/Tec finical Services *
54,209
| 5% ]ef Total Sampling Activities for Project Management
584,189
54,209
Lifetime Long Term Monitoring (Net Present Value) 2
5698,868
Monitoring, Sampling, Toting and Analysis - Fish
1
NPV
S405.197
5405.197
Monitoring, Sampling, Testing and Analysis - Sediment
1
NPV
1151.428
5151,428
Community Involvement
1
NPV
$134,325
5134.325
Engineer nig Control*
1 i
NPV
57,918
57,91»
10
Long-Term Sampling
Donas Reservoir 4fld Canal System
Donna, Hidalgo County, Texas
000810
-------
Alternative Component SB-A; Page 4 of 4
TECHNOLOGY
LOCATION
Estimated Cost to Implement
$11,300,900
Dredging of Canal Sediment with Off-Site Disposal
Alternative Component SE-A
Donna Reservoir and Canal System
Donna. TX
Const ruction Time:
Operation Time:
Posl Remediation Monitoring
Quantities
Cost Breakdown tif available!
Labor Labor Equipment Equipment
Unit Cost Total Cost Unit C'cwt Total Cost
Combined Unit
Costs
Daui Source
(Means1 or Other)
Quantity
Amount
Quantity
Uait
Mm en ;il Material
Unit Cost Total Cos)
Option
Total L'o.st
IP Community Involvement and Engmaerittg Controls
7% DiscuuE^^jy^gc^EP^^uidanct^
TOTAL ESTIMATED NPV TECHNOLOGY COST
SIMOCMHM
Asiumptiant'.
General
Working condition is Safety Level:
D
Labor productivity £ 81% j.
Weighted Average of city cost index
06.8%
(not applicable for costs derived from vendor quotes),
Costs are loaded with mark-up
10%
Inflation
3%
per yeai | 6% |fo* 2 u-hh [ 13%
Sales Tax
8.25%
Durins Emotion
Density Of Sediment
1.4
Ittn/CY
Workers work week consists of
6
days 'week | I fogs
1
mobilixsttiorf'ttetnabilijtatians per excavator
Length of canal scgmcni for excavation
4,486
feet
Approximate width nf canal
55.S
feet
Approximate depth of excavation
2.17
feet
DiSDOJj*'
Approximate quantity of concrete for stabilization
7%
by weight
Disposal rate
20
itwids'Clav
Annual Fish Sajtinlinti
Sampling to be tcuvduEted
1
time per year
Fish Tissue Samples
35
sample
Quality Con no! Samples.
3
4 of MSAfSDs to euMcct
Duplicate
3
if of duplicates to collect
Tcnn McMtitoriitg Report*
40
hours per report (1 report per event)
Standard work day
12
hrs
Approximate hourly wage Junior Engidocr
S10LMM
Construction Manager
S 1*40.0*1
Community Outreach Representative
SI 10.00
Equipment pRHiucciviry.^
to y
J per diem per rig
Ml?
Sedimfftu
BCD Congenerx
Fi iit TissueJ
PCB ml AfoelHn,
Nftt«
0CY
In-place cubic yard
Cubic yard
Each
Foot
Gallon
Hours
borsc. power
If&S
LCY
Lf
SF
SY
VLF
Health and Safety
Loow cubic yard
Linear foot
Square fool
Square yard
Vertical linear fool
Source !¦) The Gonlian Group, RS Mcuit$ Online (201 (Tj, McAllcn, TX, unlixss otherwise cited
Source of factor: "A Guide to Developing unci DocutnetuiJig Cost Estimates During the Feasibility Study." US EPA (July 2QWtt|
ii-.h tissue- analyses include cost for lipids and Bjlghtt
Donna Reservoir 4«d Cunal System
Dijtmfl, IFidalgo Cuuety, Texas
000811
-------
Appendix D
Determination of Applicable or Relevant
and Appropriate Requirements and To-Be-Considered
000812
-------
Appendix D; Page 1 of 4
APPENDIX D
APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS AND TO BE CONSIDERED
ARAR or TBC
Citation (If Available)
Description
Applicability
Chemical Specific
None I I I
Location Specific
National Historical Preservation Act
16 U.S.C. § 470 et. seq.; 36 C.F.R. Parts 63, 65,
and 800
Establishes procedures to preserve scientific, historical, and archeological data from potential
destruction resulting from a change in the site terrain resulting from a federal construction
project or federally licensed activity.
Applicable if scientific, historical, and archeological data is
discovered during the project
National Flood Insurance Program
42 U.S.C. § 4101 et. seq;. 44 C.F.R Part 60
Prohibits alteration to river or floodplains that may increase potential for flooding.
Applicable because the site lies within a 100-year floodplain.
Executive Order 11988
Floodplains Management
42 Fed. Reg. 26951 (May 24,1977)
Requires federal agencies to evaluate the potential affects of actions they may take in a
floodplain to avoid adverse impacts in a floodplain.
Applicable because the site lies within a 100-year floodplain.
Endangered Species Act of 1973
16 U.S.C. §§ 1531, 1532, 1533, 1535, 1536; 50
C.F.R. Part 17
Federal agencies must confirm any action that is federally authorized, funded, or
implemented by the agency is not probable to adversely affect the continued existence of any
threatened or endangered species. There is uncertainty regarding whether threatened and
endangered species are located at the Site.
Applicable if threatened or endangered species are found onsite.
Texas Administrative Code, Title 31 Natural
Resources and Conservation, Part 2 Texas
Parks and Wildlife Department, Chapter 65
Wildlife
31 Texas Admin. Code § 65.171-176
No person may take, possess, propogate, transport, sell or offer for sale, or ship any species
of fish or wildlife listed as threatened or endangered. There is uncertainty regarding whether
threatened and endangered species are located at the Site. The ERA assumed that any
threatened or endangered species that could occur within Hidalgo County may be present at
the Site.
Applicable if threatened or endangered species are found onsite.
Migratory Bird Treaty Act
16 U.S.C. §§ 703-712
Establishes federal responsibility for the protection of international migratory bird resources
and requires continued consultation with the U.S. Fish and Wildlife Service during remedial
design and remedial action activities to ensure that the cleanup of the site does not
unnecessarily impact migratory birds.
Applicable if the remedy may impact migratory birds.
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
000813
-------
Appendix D; Page 2 of 4
APPENDIX D
APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS AND TO BE CONSIDERED
ARAR or TBC
Citation (If Available)
Description
Applicability
Action Specific
Disposal
Resource Conservation and Recovery Act
(RCRA) Subchapter ID: Hazardous Waste
Management
42 U.S.C. §§ 6921 et seq.; 40 C.F.R. Part 262
RCRA Subchapter HI C and its implementing regulations regulate the management of
hazardous wastes. 40 C.F.R. Part 262 regulates generators of hazardous wastes.
Applicable if waste materials generated during remedial activities
contain RCRA listed hazardous wastes or exhibit a hazardous
waste characteristic.
Texas Administrative Code, Title 30
Environmental Quality, Part 1 Texas
Commission on Environmental Quality,
Chapter 335 Industrial Solid Waste and
Municipal Hazardous Waste
30 Tex. Admin. Code Chapter 335
Standards for industrial solid waste and municipal hazardous waste depending on
classification as hazardous, Class 1, Class 2, or Class 3 waste. 30 Tex. Admin. Code
335.508(5) states that media contaminated by a material containing greater than or equal to
50 ppm total PCBs and wastes containing greater than or equal to 50 ppm PCBs shall be
classified as Class 1 waste.
Applicable if hazardous, Class 1, Class 2 or Class 3 waste is
generated during remedial activities.
Toxic Substances Control Act PCB Regulations
15 U.S.C. § 2601 et. seq.; 40 C.F.R. Part 761
The Toxic Substances Control Act (TSCA) PCB regulations regulate PCBs from their
manufacture to disposal.
Applicable if PCB remediation waste is generated during remedial
activities.
Hazardous Materials Transportation Act
49 U.S.C. §§ 5101 et seq.; 49 C.F.R. Parts 171-
180
Standards for packaging, documenting and transporting hazardous materials.
Applicable if hazardous materials are transported off-site for
treatment or disposal.
Remediation Activities
Texas Administrative Code, Title 30
Environmental Quality, Part 1 Texas
Commission on Environmental Quality,
Chapter 327 Spill Prevention and Control
30 Texas Admin. Code Chapter 327
Chapter 327 of Title 30 of the Texas Administrative Code defines reportable quantities,
notification requirements, and actions required in the event of a spill or release to the
environment of oil, petroleum product, used oil, hazardous substances, industrial solid waste
or other substances.
Applicable if a release or spill to the environment occurs during
remedial activities.
Clean Water Act Section 401: Certification
33 U.S.C. § 1341
Requires applicants for NPDES permits to obtain certification from state or regional
regulatory agencies that the proposed discharge will comply with CWA Sections 301, 302,
303, 306 and 307. On-site discharges would not require a NPDES permit, but would require
compliance with substantive requirements. For off-site actions, certification should occur as
part of the state identification of substantive state ARARs (USEPA 1998).
Applicable if remedial activities result in a discharge of a pollutant
to navigable waters of the United States.
Clean Water Act Section 402: National
Pollutant Discharge Elimination System
33 U.S.C. § 1342; 40 C.F.R. Part 125
Both on-site and off-site discharges of pollutants from CERCLA sites to navigable waters of
the United States are required to meet the substantive requirements of the Clean Water Act
(CWA) National Pollutant Discharge Elimination System (NPDES) (USEPA 1988). On-site
discharges must comply with the substantive technical requirements of the CWA but do not
require a permit Off-site discharges would be regulated under the conditions of a NPDES
permit. In Texas, the NPDES program is administered by TCEQ~see Texas Water Code,
Title 2 Water Administration, Chapter 26 Water Quality Control.
Applicable if remedial activities result in a discharge of a pollutant
to navigable waters of the United States.
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
000814
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Appendix D; Page 3 of 4
APPENDIX D
APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS AND TO BE CONSIDERED
ARARor TIM"
Ciimion (If Available)
Description
Applicnhilily
Clean Water Act Section 404: Permits for
dredged or fill material
33 U.S.C. § 1344
Section 404 of the Clean Water Act applies to dredging, in-water disposal, capping,
construction of berms or levees, stream chanelization, excavation and/or dewatering in
navigable waters of the United States.
Applicable if remedial activities result in a discharge of a pollutant
to navigable waters of the United States.
Texas Administrative Code, Title 30
Environmental Quality, Part 1 Texas
Commission on Environmental Quality,
Chapter 279 Water Quality Certification
30 Texas Admin. Code Chapter 279
Establishes procedures and criteria for applying for, processing and reviewing state
certifications under CWA Section 401.
Applicable if remedial activities result in a discharge of a pollutant
to navigable waters of the United States.
Clean Water Act Sections 303 and 304: Federal
Water Quality Criteria
33 U.S.C. § 1313-14
Under §303 (33 U.S.C. §1313), individual states have established water quality standards to
protect existing and attainable uses of surface water.
Applicable if remedial activities result in a discharge of a pollutant
to navigable waters of die United States.
Texas Water Code, Title 2 Water
Administration, Chapter 26 Water Quality
Control
Tex. Water Code § 26.121
Prohibits any discharge of pollutants into or adjacent to waters in the state except as
authorized by TCEQ. TCEQ is delegated the authority to issue permits for the discharge of
pollutants to the same extent as the NPDES permit program administered by the EPA under
CWA Section 402. On-site discharges must comply with the substnative requirements of the
CWA but do not require a permit Off-site discharges would be regulated under the
conditions of a TPDES permit Direct discharges must meet technology-based requirements.
Applicable if remedial activities result in a discharge of a pollutant
to navigable waters of the United States.
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
000815
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Appendix D; Page 4 of 4
APPENDIX D
APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS AND TO BE CONSIDERED
ARAR or LIK
Citation (If Available)
Description
Applicability
Texas Administrative Code, Title 30
Environmental Quality, Part 1 Texas
Commission on Environmental Quality,
Chapter 307 Texas Surface Water Quality
Standards
30 Tex. Admin. Code Chapter 307
Sets forth criteria for surface water in Texas.
Applicable if remedial activities occur in the Arroyo Colorado
River.
Rivers and Harbors Act of 1899: Obstruction of
navigable waters (generally, wharves; piers,
etc.); excavation and fill
33 U.S.C. § 401
Controls the alteration of navigable waters, including construction of structures such as piers,
berms and installation of pilings as well as excavation and fill. No permit is required for on-
site activities, but in-water construction activities must comply with die substantive
requirements of the Act
Applicable if remedial activities require construction in navigable
waters of the United States.
Fish and Wildlife Coordination Act
16 U.S.C. § 662 et. seq.
When modifications to a stream or other water body are proposed or approved by any United
States agency, such agency shall review with the U.S. Fish and Wildlife Service, Department
of the Interior, and with the head of the agency overseeing the wildlife resources of the site.
Applicable if remedial activities would modify streams or other
water bodies.
Notes:
ARAR - Applicable or relevant and appropriate requirements
CERCLA - Comprehensive Environmental Response, Compensation and Liabilities Act
PCB - Polychlorinated biphenyls
RCRA - Resource Conservation and Recovery Act
TBC - To be considered
Donna Reservoir and Canal System
Donna, Hidalgo County, Texas
000816
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