United States 

Environmental Protection 

Agency 

1200 Pennsylvania Avenue, N.W. 

Washington, D.C. 20460 March 2011 

Office of Solid Waste and Emergency Response

Support Document for the 

Revised National Priorities List 

Final Rule – Wright Chemical Corporation
Support Document for the 

Revised National Priorities List 

Final Rule 

Wright Chemical Corporation 

March 2011 

Site Assessment and Remedy Decisions Branch 

Office of Superfund Remediation and Technology Innovation 

Office of Solid Waste and Emergency Response 

U.S. Environmental Protection Agency 

Washington, DC 20460
Wright Chemical Corporation NPL Listing Support Document March 2011 

Table of Contents

Executive Summary ...................................................................................................................................iii

Introduction................................................................................................................................................iv

Background of the NPL...........................................................................................................................iv

Development of the NPL..........................................................................................................................v

Hazard Ranking System ...........................................................................................................................v

Other Mechanisms for Listing.................................................................................................................vi

Organization of this Document...............................................................................................................vii

Glossary..................................................................................................................................................vii

1. List of Commenters and Correspondence........................................................................................1

2. Site Description...................................................................................................................................1

3. Summary of Comments .....................................................................................................................2

3.1 Support for Listing........................................................................................................................2

3.3 Need for Remediation ...................................................................................................................5

3.4 Incomplete Exposure Route/No Risk............................................................................................6

3.5 Oak-Bark/Hexion Facility - No Further Effort Needed ................................................................6

3.6 Deferral to Other Programs...........................................................................................................6

3.7 Description of In-Water Segment .................................................................................................7

3.8 Observed Release to Livingston Creek – Significant Increase .....................................................8

3.9 Observed Release by Chemical Analysis - Attribution...............................................................10

3.9.1 Association with Site Source.............................................................................................................14

3.9.2 Other Facilities..................................................................................................................................15

3.10 Waste Characteristics..................................................................................................................18

3.10.1 Waste Quantity..................................................................................................................................18

3.10.2 Eligible Hazardous Substances..........................................................................................................20

3.10.3 Assignment of Bioaccumulation Factor Values................................................................................22

3.10.4 Containment ......................................................................................................................................24

3.11 Targets.........................................................................................................................................25

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Wright Chemical Corporation Comment Summary 9/30/2010

 ii 

3.11.1 Presence of Private Receptors...........................................................................................................25

3.11.2 Zone of Contamination......................................................................................................................26

4. Conclusion.........................................................................................................................................28
Wright Chemical Corporation NPL Listing Support Document March 2011 

Executive Summary 

Section 105(a)(8)(B) of CERCLA, as amended by SARA, requires that the EPA prepare a list of national 

priorities among the known releases or threatened releases of hazardous substances, pollutants, or 

contaminants throughout the United States. An original National Priorities List (NPL) was promulgated 

on September 8, 1983 (48 FR 40658). CERCLA requires that EPA update the list at least annually. 

This document provides responses to public comments received on the Wright Chemical Corporation site, 

proposed on March 4, 2010 (75 FR 9843). This site is being added to the NPL based on an evaluation 

under EPA’s Hazard Ranking System (HRS) in a final rule published in the Federal Register in March 

2011. 

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Wright Chemical Corporation Listing Support Document March 2011 

Introduction 

This document explains the rationale for adding the Wright Chemical Corporation site in Riegelwood, 

North Carolina, to the National Priorities List (NPL) of uncontrolled hazardous waste sites and provides 

responses to public comments received on this site listing proposal. The EPA proposed this site to the 

NPL on March 4, 2010 (75 FR 9843). This site is being added to the NPL based on an evaluation under 

the Hazard Ranking System (HRS) in a final rule published in the Federal Register in March 2011. 

Background of the NPL 

In 1980, Congress enacted the Comprehensive Environmental Response, Compensation, and Liability Act 

(CERCLA), 42 U.S.C. Sections 9601 et seq. in response to the dangers of uncontrolled hazardous waste 

sites. CERCLA was amended on October 17, 1986, by the Superfund Amendments and Reauthorization 

Act (SARA), Public Law No. 99-499, stat., 1613 et seq. To implement CERCLA, EPA promulgated the 

revised National Oil and Hazardous Substances Pollution Contingency Plan (NCP), 40 CFR Part 300, on 

July 16, 1982 (47 FR 31180), pursuant to CERCLA Section 105 and Executive Order 12316 (46 FR 

42237, August 20, 1981). The NCP, further revised by EPA on September 16, 1985 (50 FR 37624) and 

November 20, 1985 (50 FR 47912), sets forth guidelines and procedures needed to respond under 

CERCLA to releases and threatened releases of hazardous substances, pollutants, or contaminants. On 

March 8, 1990 (55 FR 8666), EPA further revised the NCP in response to SARA. 

Section 105(a)(8)(A) of CERCLA, as amended by SARA, requires that the NCP include 

criteria for determining priorities among releases or threatened releases throughout the 

United States for the purpose of taking remedial action and, to the extent practicable, take 

into account the potential urgency of such action, for the purpose of taking removal 

action. 

Removal action involves cleanup or other actions that are taken in response to emergency conditions or 

on a short-term or temporary basis (CERCLA Section 101). Remedial action is generally long-term in 

nature and involves response actions that are consistent with a permanent remedy for a release (CERCLA 

Section 101). Criteria for placing sites on the NPL, which makes them eligible for remedial actions 

financed by the Trust Fund established under CERCLA, were included in the HRS. EPA promulgated the 

HRS as Appendix A of the NCP (47 FR 31219, July 16, 1982). On December 14, 1990 (56 FR 51532), 

EPA promulgated revisions to the HRS in response to SARA, and established the effective date for the 

HRS revisions as March 15, 1991. 

Section 105(a)(8)(B) of CERCLA, as amended, requires that the statutory criteria provided by the HRS be 

used to prepare a list of national priorities among the known releases or threatened releases of hazardous 

substances, pollutants, or contaminants throughout the United States. The list, which is Appendix B of 

the NCP, is the NPL. 

An original NPL of 406 sites was promulgated on September 8, 1983 (48 FR 40658). At that time, an 

HRS score of 28.5 was established as the cutoff for listing because it yielded an initial NPL of at least 400 

sites, as suggested by CERCLA. The NPL has been expanded several times since then, most recently on 

September 29, 2010 (75 FR 59975). The Agency also has published a number of proposed rulemakings 

to add sites to the NPL. The most recent proposal was on October 21, 2010 (75 FR 64976). 

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Wright Chemical Corporation Listing Support Document March 2011 

Development of the NPL 

The primary purpose of the NPL is stated in the legislative history of CERCLA (Report of the Committee 

on Environment and Public Works, Senate Report No. 96-848, 96th Cong., 2d Sess. 60 [1980]). 

The priority list serves primarily informational purposes, identifying for the States and 

the public those facilities and sites or other releases which appear to warrant remedial 

actions. Inclusion of a facility or site on the list does not in itself reflect a judgment of the 

activities of its owner or operator, it does not require those persons to undertake any 

action, nor does it assign liability to any person. Subsequent government actions will be 

necessary in order to do so, and these actions will be attended by all appropriate 

procedural safeguards. 

The NPL, therefore, is primarily an informational and management tool. The identification of a site for 

the NPL is intended primarily to guide EPA in determining which sites warrant further investigation to 

assess the nature and extent of the human health and environmental risks associated with the site and to 

determine what CERCLA-financed remedial action(s), if any, may be appropriate. The NPL also serves 

to notify the public of sites EPA believes warrant further investigation. Finally, listing a site may, to the 

extent potentially responsible parties are identifiable at the time of listing, serve as notice to such parties 

that the Agency may initiate CERCLA-financed remedial action. 

CERCLA Section 105(a)(8)(B) directs EPA to list priority sites among the known releases or threatened 

release of hazardous substances, pollutants, or contaminants, and Section 105(a)(8)(A) directs EPA to 

consider certain enumerated and other appropriate factors in doing so. Thus, as a matter of policy, EPA 

has the discretion not to use CERCLA to respond to certain types of releases. Where other authorities 

exist, placing sites on the NPL for possible remedial action under CERCLA may not be appropriate. 

Therefore, EPA has chosen not to place certain types of sites on the NPL even though CERCLA does not 

exclude such action. If, however, the Agency later determines that sites not listed as a matter of policy 

are not being properly responded to, the Agency may consider placing them on the NPL. 

Hazard Ranking System 

The HRS is the principle mechanism EPA uses to place uncontrolled waste sites on the NPL. It is a 

numerically based screening system that uses information from initial, limited investigations -- the 

preliminary assessment and site inspection -- to assess the relative potential of sites to pose a threat to 

human health or the environment. HRS scores, however, do not determine the sequence in which EPA 

funds remedial response actions, because the information collected to develop HRS scores is not 

sufficient in itself to determine either the extent of contamination or the appropriate response for a 

particular site. Moreover, the sites with the highest scores do not necessarily come to the Agency's 

attention first, so that addressing sites strictly on the basis of ranking would in some cases require 

stopping work at sites where it was already underway. Thus, EPA relies on further, more detailed studies 

in the remedial investigation/feasibility study that typically follows listing. 

The HRS uses a structured value analysis approach to scoring sites. This approach assigns numerical 

values to factors that relate to or indicate risk, based on conditions at the site. The factors are grouped 

into three categories. Each category has a maximum value. The categories are: 

• likelihood that a site has released or has the potential to release hazardous substances into the 

environment; 

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Wright Chemical Corporation Listing Support Document March 2011 

• characteristics of the waste (toxicity and waste quantity); and 

• people or sensitive environments (targets) affected by the release. 

Under the HRS, four pathways can be scored for one or more threats as identified below: 

• Ground Water Migration (Sgw) 

- drinking water 

• Surface Water Migration (Ssw) 

The following threats are evaluated for two separate migration components, overland/flood 

migration and ground water to surface water. 

- drinking water 

- human food chain 

- sensitive environments 

• Soil Exposure (Ss) 

- resident population 

- nearby population 

- sensitive environments 

• Air Migration (Sa) 

- population 

- sensitive environments 

After scores are calculated for one or more pathways according to prescribed guidelines, they are 

combined using the following root-mean-square equation to determine the overall site score (S), which 

ranges from 0 to 100: 

4

S + S + S + S = S

2

a

2

s

2

sw

2

gw

If all pathway scores are low, the HRS score is low. However, the HRS score can be relatively high even 

if only one pathway score is high. This is an important requirement for HRS scoring because some 

extremely dangerous sites pose threats through only one pathway. For example, buried leaking drums of 

hazardous substances can contaminate drinking water wells, but -- if the drums are buried deep enough 

and the substances not very volatile -- not surface water or air. 

Other Mechanisms for Listing 

There are two mechanisms other than the HRS by which sites can be placed on the NPL. The first of 

these mechanisms, authorized by the NCP at 40 CFR 300.425(c)(2), allows each State and Territory to 

designate one site as its highest priority regardless of score. The last mechanism, authorized by the NCP 

at 40 CFR 300.425(c)(3), allows listing a site if it meets the following three requirements: 

• Agency for Toxic Substances and Disease Registry (ATSDR) of the U.S. Public Health Service 

has issued a health advisory that recommends dissociation of individuals from the release; 

• EPA determines the site poses a significant threat to public health; and 

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Wright Chemical Corporation Listing Support Document March 2011 

• EPA anticipates it will be more cost-effective to use its remedial authority than to use its 

emergency removal authority to respond to the site. 

Organization of this Document 

The following section contains EPA responses to site-specific public comments received on the proposal 

of the Wright Chemical Corporation site on March 4, 2010 (75 FR 9843). The site discussion begins with 

a list of commenters, followed by a site description, a summary of comments, and Agency responses to 

each comment. A concluding statement indicates the effect of the comments on the HRS score for the 

site. 

Glossary 

The following acronyms and abbreviations are used throughout the text: 

Agency U.S. Environmental Protection Agency 

BPFV Bioaccumulation Potential Factor Value 

CAP Corrective action plan 

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act of 

1980, 42 U.S.C. Sections 9601 et seq., also known as Superfund 

CFR Code of Federal Regulations 

CRQL Contract-required quantitation limit 

CSA Comprehensive site assessment 

DL Detection limit 

EE/CA Engineering evaluation and cost analysis 

EPA U.S. Environmental Protection Agency 

ESI Expanded site inspection 

FR Federal Register

HRS Hazard Ranking System, Appendix A of the NCP 

HRS score Overall site score calculated using the HRS; score ranges from 0 to 100 

MDL Method detection limit 

mg/kg Milligram per kilogram 

MRL Minimum reporting limit 

NCDENR North Carolina Department of Environment and Natural Resources 

NCP National Oil and Hazardous Substances Pollution Contingency Plan, 40 C.F.R. 

Part 300 

NOAA National Oceanic and Atmospheric Administration 

NPL National Priorities List, Appendix B of the NCP 

NTCRA Non-time critical removal action 

PEL Probable effects level 

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Wright Chemical Corporation Listing Support Document March 2011 

 viii 

PPE Probable point of entry 

PRP Potentially responsible party 

RCRA Resource Conservation and Recovery Act 

RI/FS Remedial investigation and feasibility study 

ROD Record of Decision 

SARA Superfund Amendments and Reauthorization Act 

SOP Standard operating procedure 

SQL Sample quantitation limit 

T/P/BPFV Toxicity/persistence/bioaccumulation potential factor value

TCRA Time critical removal action 

TDL Target distance limit 
Wright Chemical Corporation NPL Listing Support Document March 2011 

1. List of Commenters and Correspondence 

EPA-HQ-SFUND-2010-073-0003 Correspondence, dated December 9 2009, from Dee 

Freeman, Secretary, North Carolina Department of 

Environment and Natural Resources, letter requesting 

placement of the Wright Chemical Corporation site on 

the National Priorities List (NPL) 

EPA-HQ-SFUND-2010-073-0007 Comment, dated May 3, 2010, from John A. Andeason, 

McGrath North, Mullen & Kratz, PC LLO on behalf of 

Oak-Bark Corporation 

EPA-HQ-SFUND-2010-073-0007.1 Comment attachment, dated May 3, 2010, from John A. 

Andeason, McGrath North, Mullen & Kratz, PC LLO on 

behalf of Oak-Bark Corporation 

EPA-HQ-SFUND-2010-073-0007.2 Comment attachment, dated May 3, 2010, from John A. 

Andeason, McGrath North, Mullen & Kratz, PC LLO on 

behalf of Oak-Bark Corporation r 

EPA-HQ-SFUND-2010-073-0007.3 Comment attachment, dated May 3, 2010, from John A. 

Andeason, McGrath North, Mullen & Kratz, PC LLO on 

behalf of Oak-Bark Corporation 

EPA-HQ-SFUND-2010-073-0007.4 Comment attachment, dated May 3, 2010, from John A. 

Andeason, McGrath North, Mullen & Kratz, PC LLO on 

behalf of Oak-Bark Corporation 

EPA-HQ-SFUND-2010-073-0007.5 Comment attachment, dated May 3, 2010, from John A. 

Andeason, McGrath North, Mullen & Kratz, PC LLO on 

behalf of Oak-Bark Corporation 

EPA-HQ-SFUND-2010-073-0007.6 Comment attachment, dated May 3, 2010, from John A. 

Andeason, McGrath North, Mullen & Kratz, PC LLO on 

behalf of Oak-Bark Corporation 

2. Site Description 

The Wright Chemical Corporation site (the Site; the Wright Chemical site) is located in an industrial/rural 

area of Riegelwood, Columbus County, North Carolina, adjacent to tidal wetlands along Livingston 

Creek. Livingston Creek is a tributary of the Cape Fear River. The Site consists of contaminated soil and 

a release of contaminants to sediment within Livingston Creek. The contaminated soil is the result of 

waste materials from a former lead chamber sulfuric acid manufacturing plant being deposited into a 

wetland area contiguous to Livingston Creek. The observed release to surface water is based on 

contaminants associated with the waste material detected in Livingston Creek sediments at concentrations 

significantly greater than in background sediment samples. Observed release contaminants include lead, 

arsenic, cadmium, copper, and zinc. Livingston Creek is a freshwater body in the area of the Site; 

however, there are portions of the target distance limit (TDL) downstream that are saltwater/brackish. In 

the area of the Site, Livingston Creek is under tidal influence. In the area of the release from Wright 

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Wright Chemical Corporation Listing Support Document March 2011 

Chemical, Livingston Creek is a human food chain fishery. Figure 1 of this support document provides 

the Site location information with respect to neighboring facilities. 

3. Summary of Comments 

John A. Andreasen submitted comments on behalf of McGrath North, which represents the Oak-Bark 

Corporation of Wilmington, North Carolina. McGrath North opposed listing the Site on the NPL, and 

specifically submitted comments directed at the Site location, site size, the minimal potential private 

receptors to the surrounding community and/or environment, and the viability of other State and/or 

Federal programs. 

McGrath North stated that the Site is located immediately adjacent to a freshwater swamp which is 

influenced by Livingston Creek and that there are three other current/former facilities/sites that are 

upgradient from the Site. McGrath North raised several issues identifying other facilities that could be 

possible sources of the contamination in Livingston Creek, particularly when tidal influence is 

considered. McGrath North asserted that any connection of the Wright Chemical site to Livingston Creek 

is an incomplete chain and attribution of the Wright Chemical site is not complete. 

McGrath North questioned the size and definition of the Wright Chemical site as described in the HRS 

documentation record at proposal and asserted that the Site has been misconstrued as being much larger 

than it actually is. McGrath North questioned the presence of targets in the vicinity and stated that there 

are no potential private receptors that could be affected by releases at the Wright Chemical site and 

further stated that there has been no significant increase of contaminant concentrations in water samples 

from Livingston Creek. 

McGrath North questioned the need for remediation at this site, stating that it is agreed that arsenic and 

lead contaminated soils should be prevented from migrating off site; however, the present situation is 

stable and a cleanup is not time critical. McGrath North questioned the appropriateness of listing the 

Wright Chemical site on the NPL, stating that there are at least two other State and/or Federal programs 

that would be more appropriate for addressing the Site. McGrath North finally stated that Oak-Bark 

Corporation does not believe that the Site poses a significant threat to public health, welfare, or the 

environment. 

3.1 Support for Listing 

Comment: The State of North Carolina submitted a governor's letter (dated December 9, 2009) to the 

EPA Region 4 Administrator stating that the State agrees that the Site poses a significant threat to the 

public health and the environment and supports EPA's efforts to propose the Site for inclusion on the 

NPL. 

Response: The Wright Chemical site has been added to the NPL. Listing makes a site eligible for 

remedial actions under CERCLA, and EPA will examine the Site to determine what response, if any, is 

appropriate. Actual funding may not necessarily be undertaken in the precise order of HRS scores, 

however, and upon more detailed investigation may not be necessary at all in some cases. EPA will 

determine the need for Superfund monies for remedial activities on a site-by-site basis, taking into 

account the NPL ranking, State priorities, further site investigation, other response alternatives, and other 

factors as appropriate. EPA will not stop work at some sites to begin work at other higher-scoring sites 

added to the NPL more recently.

 2 
Figure 1: Livingston Creek and Cape Fear River

Site: Wright Chemical Corp.NCD 024 766 719 Date: 05Columbus Co., NC Drawn B

Aerial P

Cape Fear River

LCV2

LCV (pre-2005)

~ 1⁄2 mile

Mill Creek

See Ref. 7 of HRS Doc Record for figure source information

Livingston

Creek

Livingston

Creek

Wright Chemical Hexion

Holtrachem

International Paper

Kaiser Agricultural

Kaiser Acme Farmarket
Wright Chemical Corporation Listing Support Document March 2011 

3.2 Site Description/Definition of Site 

Comment: McGrath North questioned the size and definition of the Site as described in the HRS 

documentation record at proposal. McGrath North asserted that the Site has been misconstrued as being 

much larger than it actually is. McGrath North stated that the former sulfuric acid facility is only 

approximately one acre in size and that the contamination from this source has been spread to a larger 

area including a slope leading to a freshwater swamp. McGrath North stated that the approximate extent 

of the known contaminated area is only 6 acres. McGrath North attached a figure (Figure 3 - 

Approximate Area of Contamination, prepared by Shields Engineering Inc., April 2010) delineating an 

approximate 6-acre area of contamination. McGrath North noted that this is a significantly smaller area 

than the 80 acres designated in the HRS documentation record. McGrath North further stated, "As can be 

seen on Figure 3, the probable extent of the magenta contamination can be fairly readily seen. This 

contamination does not appear to be migrating to the surrounding community." 

Response: While the property on which the Wright Chemical facility is located is 80 acres in size, the 

Wright Chemical site is not defined by the property boundaries. It is defined by the area of 

contamination. The HRS documentation record at proposal described both the Wright Chemical facility 

property and the Wright Chemical site area. The HRS documentation record at proposal stated on page 

15 that the Wright Chemical facility includes an area of magenta-colored soil that is primarily located on 

two parcels that total about 80 acres. The Wright Chemical site for HRS evaluation purposes includes the 

contaminated soil from the three subareas of Source 1 described on pages 15-16 of the HRS 

documentation record at proposal, as well as the contaminated sediments in Livingston Creek as 

described on page 30 of the HRS documentation record at proposal. 

The extent of a site and its boundaries are not defined at the time of listing. Rather, placing a site on the 

NPL is based on an evaluation, in accordance with the HRS, of a release or threatened release of 

hazardous substances, pollutants, or contaminants. The fact that EPA initially identifies and lists the 

release based on a review of contamination at a certain parcel of property does not necessarily mean that 

the site boundaries are limited to that parcel. 

CERCLA Section 105(a)(8)(A) requires EPA to list national priorities among the known “releases or 

threatened releases” of hazardous substances; thus, the focus is on the release, not precisely delineated 

boundaries. Further, CERCLA Section 101(a) defines a “facility” as the “site” where a hazardous 

substance has been “deposited, stored, placed, or otherwise come to be located.” The “come to be 

located” language gives EPA broad authority to clean up contamination when it has spread from the 

original source. 

 

The revised HRS (55 FR 51587, December 14, 1990) elaborates on the “come to be located” language, 

defining “site” as “area(s) where a hazardous substance has been deposited, stored, disposed, or placed, or 

has otherwise come to be located. Such areas may include multiple sources, and may include the area 

between the sources.” 

On April 9, 2009 (74 FR 16165), EPA stated: 

The NPL does not describe releases in precise geographical terms; it would be neither 

feasible nor consistent with the limited purpose of the NPL (to identify releases that are 

priorities for further evaluation), for it to do so. . . . [T]he HRS inquiry focuses on an 

evaluation of the threat posed and therefore the boundaries of the release need not be 

exactly defined. Moreover, it generally is impossible to discover the full extent of where 

the contamination ‘has come to located’ before all necessary studies and remedial work 

are completed at a site. . . .During the RI/FS [remedial investigation/feasibility study] 

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Wright Chemical Corporation Listing Support Document March 2011 

process, the release may be found to be larger or smaller than was originally thought, as 

more is learned about the source(s) and the migration of the contamination. . . . [T]he 

known boundaries of the contamination can be expected to change over time. 

Until the site investigation process has been completed and a remedial action (if any) selected, EPA can 

neither estimate the extent of contamination at the site, nor describe the ultimate dimensions of the NPL 

site. Even during a remedial action EPA may find that the contamination has spread further than 

previously estimated. In addition, if another, unrelated area of contamination is discovered elsewhere on 

the property, EPA may decide to evaluate that release for the NPL. 

Regarding the visual observations made on Figure 3 in the HRS documentation record at proposal, 

McGrath North stated that the magenta-colored staining appears to be localized. This statement does not 

mean the contamination, or the Site, is limited to the stained area (see section 3.10.1 of this support 

document for additional waste quantity information), In fact, the analytical results from sediment samples 

collected from Livingston Creek in April 2007 indicate that contaminants associated with the evaluated 

site source (i.e., contaminated soil) are migrating to Livingston Creek (see pp. 19, 29; Ref. 4 pp. 34, 36, 

41, 57, 59, 61-62, 65-and 66 67). This contradicts McGrath North's assertion that contamination does not 

appear to be migrating to the surrounding community. 

This comment has no effect on the HRS Site score or the decision to place the Site on the NPL. 

 

3.3 Need for Remediation 

Comment: McGrath North questioned the need for remediation at this site, stating that it is agreed “that 

arsenic and lead contaminated soils should be prevented from migrating off site; however, the present 

situation is stable and a cleanup is not time critical.” 

Response: Listing a site on the NPL does not represent a finding that remedial action is necessary or will 

be taken, but that further investigation is necessary. Consideration of future response actions is not a 

factor in the decision to list a site on the NPL. The remedy selection phase of the CERCLA process is a 

separate step, which occurs after appropriate remedial investigations and risk assessments have been 

completed. In general, under the Superfund program, EPA investigates sites in two stages: 

1. Site assessment: a screening-level evaluation of all sites to determine those for which response 

action may be required, culminating in the listing of sites on the NPL, where appropriate; and 

2. Response action: a comprehensive evaluation of NPL sites to determine the nature and extent of 

contamination, and to select and implement any necessary site cleanup actions. 

It is only in the second stage that EPA will be able to select an appropriate remedy, if any is needed, for a 

site. At this site, further study is necessary to determine whether sufficient information is available to 

perform a complete site-specific risk assessment. Based on the site-specific risk assessment, EPA will 

then determine what remedy, if any, is necessary. 

Regarding whether there is a need for a time critical removal action1

, a site-specific risk assessment is 

normally performed after listing as a separate part of the Superfund process. See section 3.6 of this 

support document for further explanation of time critical removal actions. 

 

1

 Time critical removal actions are expedited removal actions used to address situations in which acute impacts are 

imminent. 

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Wright Chemical Corporation Listing Support Document March 2011 

This comment has no effect on the HRS Site score or the decision to place the Site on the NPL. 

3.4 Incomplete Exposure Route/No Risk

Comment: McGrath North questioned EPA’s conclusion that the source associated with the Wright 

Chemical Corporation site is impacting surface water quality or the biota or humans ingesting the biota 

within Livingston Creek. McGrath North also stated that Oak-Bark Corporation does not believe that the 

Site poses a significant threat to public health, welfare or the environment. 

Response: The Site’s HRS score shows that the Site presents sufficient risk to be placed on the NPL for 

further study and possible response action. 

A site-specific risk assessment will be performed as part of the Superfund response process that occurs 

after the listing process is completed. At that time, EPA will consider the information provided by 

McGrath North. The results of the risk assessment will be considered if and when remedial options at the 

Site are selected. 

 

McGrath North’s assertion that it does not believe the Site poses a significant threat to public health, 

welfare, or the environment is not supported by a site-specific risk assessment. As the HRS score, HRS 

documentation record, and this support document shows, the Site poses sufficient threat to public health, 

and the environment to warrant further investigation. 

This comment has no effect on the HRS Site score or the decision to place the Site on the NPL.

3.5 Oak-Bark/Hexion Facility - No Further Effort Needed

Comment: McGrath North stated that adjacent to the former lead chamber sulfuric acid plant is a 

currently operating facility owned by Oak-Bark Corporation and Hexion. McGrath North identified that 

this facility has only been used for the manufacturing of organic chemicals and products. Under the 

direction of the North Carolina Department of Environment and Natural Resources (NCDENR), four 

unlined lagoons were closed at the facility in 1994. A comprehensive site assessment (CSA) and a 

corrective action plan (CAP) were submitted in 1997. The CSA determined that arsenic and lead were 

not Site ground water contaminants and were therefore not included in the CAP. In 1998, NCDENR 

approved the CAP for "using the natural attenuation process." McGrath North concluded by stating that 

ground water data (1997 to 2010) shows that the natural attenuation process is reducing the contaminant 

levels in the area of the facility. 

Response: McGrath North’s comments about the adjacent facilities have no effect on listing the Wright 

Chemical facility. Because arsenic and lead were not found to be related to the four unlined lagoons at 

the neighboring facility does not affect the listing of contaminated soil at the Wright Chemical facility. 

The release at the Site is attributable, at least in part, to releases associated with the denuded contaminated 

soil located on the Wright Chemical site, and neither the Oak Bark Corporation or Hexion facilities have 

been evaluated as part of this site (see sections 3.9.1 and 3.9.2 of this support document). 

This comment has no effect on the HRS Site score or the decision to place the Site on the NPL. 

3.6 Deferral to Other Programs 

Comment: McGrath North questioned the appropriateness of listing the Wright Chemical Corporation 

site on the NPL, stating that there are at least two other State and/or Federal programs that would be more 

 6 
Wright Chemical Corporation Listing Support Document March 2011 

appropriate for the Site. One program mentioned by McGrath North is NCDENR Inactive Hazardous 

Sites Branch Registered Consultant Program, or Voluntary Cleanup Program. A second and, McGrath 

North indicated, a more desirable program would be the EPA non-time or time critical removal action 

(NTCRA, TCRA), or the engineering evaluation and cost analysis (EE/CA) program. McGrath North 

stated that most of the former lead chamber/fertilizer sites are going through the EE/CA program or 

NTCRA process. 

Response: This site qualifies for the NPL based on assignment of an HRS score above 28.50, and the 

State of North Carolina has requested that the Site be placed on the NPL. None of the programs 

mentioned by McGrath North contain any provisions that would preclude EPA from pursuing the listing 

under CERCLA. Thus, EPA has no reason to defer this site to another EPA or other remedial program. 

In addition, the State support for the placement of this site on the NPL demonstrates that the State does 

not wish the Site to be placed in an alternative state program. EPA does not consider that, based on the 

information presently available, the threat posed by the Site meets the criteria for imminent and 

substantial endangerment per Section 415(b) of the NCP for either a time critical or a non-time critical 

removal. If future evaluation during the RI/FS shows that a removal is needed, EPA will consider options 

for a time or non-time critical removal at that time. 

The Secretary for the NCDENR submitted a letter to the EPA Region 4 Administrator December 9, 2009, 

stating that the State of North Carolina agrees that the Site poses a significant threat to the public health 

and the environment, and indicates State support of EPA's efforts to propose the Site for inclusion on the 

NPL (regulations.gov, Docket ID. EPA-HQ-SFUND-2010-0073). As stated in section 3.2 of this support 

document, the need for any site-specific response action is determined after listing at a different stage in 

the Superfund process. 

This comment has no effect on the HRS Site score or the decision to place the Site on the NPL. 

3.7 Description of In-Water Segment 

Comment: McGrath North asserted that surface water near the Wright Chemical Corporation site is fresh 

water. McGrath North stated that adjacent to the Site is a freshwater swamp that is influenced by 

Livingston Creek. 

Response: EPA agrees with the comment and acknowledges that in the HRS documentation record at 

proposal the surface water near the Wright Chemical Corporation site is fresh water. 

Page 24 of the HRS documentation record at proposal under the title, Definition of Hazardous Substance 

Migration Path for Overland/Flood Component, stated: 

The point where Livingston Creek flows into the Cape Fear River is 27 1/2 miles 

upstream from Wilmington. The point where the Cape Fear joins the Black River is 

the upstream intrusion limit (200 mg/L chloride), having a 50% chance of being 

equaled or exceeded in any one year (Ref. 4, pp. 296, 309). Saltwater intrusion may 

affect water quality as far as 20 miles upstream from Wilmington (Ref. 4, p. 300). 

Therefore, the first 10 1/2 miles of the surface water pathway is fresh, and the last 4 

1/2 miles of the surface water pathway is brackish/salt. 

Section 3.10.3 of this support document discusses the assignment of factor values based on salinity and 

explains that whereas the substances used to assign the bioaccumulation factor value are different 

 7 
Wright Chemical Corporation Listing Support Document March 2011 

depending on the salinity of the water, the bioaccumulation factor value remains the same regardless of 

the water salinity. 

This comment has no effect on the HRS Site score or the decision to place the Site on the NPL. 

3.8 Observed Release to Livingston Creek – Significant Increase 

Comment: McGrath North contested the observed release of contaminants to surface water, claiming that 

there has been no significant increase of contaminant concentrations in water samples from Livingston 

Creek. McGrath North stated that as part of a State of North Carolina CAP for addressing the closure of 

four unlined lagoons at Hexion, Livingston Creek was monitored upstream and downstream of the Site to 

document any potential impact. It continued by stating that from 1997 to 2003, the creek was sampled for 

chromium, copper, lead, and zinc with few concentrations above detection limits and none above 

background concentrations. It further stated that surface water samples collected in 2009 and 2010 

included analyses for arsenic and lead; none of the surface water samples exhibited sample concentrations 

of lead or arsenic above the detection limit of 10 micrograms per liter (μg/L). In addition, McGrath North 

noted that cadmium was included in the March 17, 2010, sampling event and cadmium was not detected 

above the detection limit of 1 μg/L. 

McGrath North asserted that, in summary, surface water analyses have shown no impact to surface water 

quality attributable to the former lead chamber acid plant. In addition, a surface water station used by the 

Center of Marine Sciences for UNC Wilmington is located along Livingston Creek. McGrath North 

stated that analytical results from samples collected 6 times per year between 2001 and 2006 indicated 

that all Priority Pollutant Metals (including arsenic, cadmium, and lead) were not detected above 

analytical detection limits for all samples collected from Livingston Creek. 

Response: The likelihood of release value for the Wright Chemical Corporation site was appropriately 

assigned according to the HRS, as an observed release by chemical analysis was documented for 

Livingston Creek. The release was based on analytical results from sediment samples collected from 

Livingston Creek. The HRS does not require that releases be based solely on surface water samples, nor 

does the absence of a release in surface water samples negate releases established based on sediment 

samples.

HRS Section 2.3, Likelihood of release, states: 

Likelihood of release is a measure of the likelihood that a waste has been or will be 

released to the environment. The likelihood of release factor category is assigned the 

maximum value of 550 for a migration pathway whenever the criteria for an observed 

release are met for that pathway. If the criteria for an observed release are met, do not 

evaluate potential to release for that pathway. When the criteria for an observed release 

are not met, evaluate potential to release for that pathway, with a maximum value of 500. 

The evaluation of potential to release varies by migration pathway (see sections 3, 4 and 

6). 

Establish an observed release either by direct observation of the release of a hazardous 

substance into the media being evaluated (for example, surface water) or by chemical 

analysis of samples appropriate to the pathway being evaluated (see sections 3, 4, and 6). 

The minimum standard to establish an observed release by chemical analysis is analytical 

evidence of a hazardous substance in the media significantly above the background level. 

Further, some portion of the release must be attributable to the Site. Use the criteria in 

table 2–3 as the standard for determining analytical significance. (The criteria in table 2–

 8 
Wright Chemical Corporation Listing Support Document March 2011 

3 are also used in establishing observed contamination for the soil exposure pathway, see 

section 5.0.1.) Separate criteria apply to radionuclides (see section 7.1.1). 

Table 2–3—Observed Release Criteria for Chemical Analysis 

Sample Measurement < Sample Quantitation Limit a

No observed release is established.

Sample Measurement ≥ Sample Quantitation Limit a

An observed release is established as follows:

• If the background concentration is not detected (or is less 

than the detection limit), an observed release is established 

when the sample measurement equals or exceeds the sample 

quantitation limit.a

• If the background concentration equals or exceeds the 

detection limit, an observed release is established when the 

sample measurement is 3 times or more above the 

background concentration.

a

 If the sample quantitation limit (SQL) cannot be established, determine if there is an 

observed release as follows: 

— If the sample analysis was performed under the EPA Contract Laboratory Program, 

use the EPA contract-required quantitation limit (CRQL) in place of the SQL. 

— If the sample analysis is not performed under the EPA Contract Laboratory Program, 

use the detection limit (DL) in place of the SQL. 

Further, HRS Section 4.1.2.1.1, Observed release, contains the directions used to establish an observed 

release to the surface water migration pathway. It states in part: 

Establish an observed release to surface water for a watershed by demonstrating that the 

site has released a hazardous substance to the surface water in the watershed. . . . 

• Chemical analysis: 

- Analysis of surface water, benthic, or sediment samples indicates that 

the concentration of hazardous substance(s) has increased significantly 

above the background concentration for the site for that type of sample 

(see section 2.3). [emphasis added] 

-Limit comparisons to similar types of samples and background 

concentrations – for example, compare surface water samples to 

surface water background concentrations. 

-For benthic samples, limit comparisons to essentially sessile 

organisms. 

- Some portion of the significant increase must be attributable to the site to 

establish the observed release, except: when the site itself consists of 

 9 
Wright Chemical Corporation Listing Support Document March 2011 

contaminated sediments with no identified source, no separate attribution 

is required.

If an observed release can be established for a watershed, assign an observed release 

factor value of 550 to that watershed, enter this value in Table 4-1, and proceed to section 

4.1.2.1.3.

The significant increase in arsenic, cadmium, copper, lead, and zinc is documented in the HRS 

documentation record at proposal on pages 27-30 which include tables 4 and 6 that display the 

background and release concentrations of hazardous substances found in Livingston Creek and Mill 

Creek sediments. These tables show that sediment samples WC-003-SD, WC-013-SD, and WC-006-SD 

meet the criteria for a significant increase as hazardous substances have been detected at concentrations 

significantly above background levels based on samples WC-001-SD WC-002-SD WC-008-SD WC-009-

SD WC-010-SD. Contaminants qualifying for the observed release to Livingston Creek include arsenic, 

cadmium, copper, lead, and zinc. 

Page 30 of the HRS documentation record at proposal, under the heading “Hazardous substances in 

observed release summary,” stated: 

 Sample WC-003-SD and its duplicate WC-013-SD serve to document the observed 

release of arsenic, cadmium, copper, lead, and zinc into the fishery. While samples just 

downstream of the site (WC-004-SD and WC-005-SD) did not show site contaminants, 

sample WC-006-SD showed higher levels of site contaminants. 

Although McGrath North stated that surface water samples collected from 1997 to 2010 did not indicate 

metals contamination to Livingston Creek, the observed release of contaminants to Livingston Creek is 

based on an evaluation of sediment samples collected during a 2007 Expanded Site Inspection (ESI) 

conducted by the North Carolina Superfund Section. As stated in HRS section 4.1.2.1.1, quoted above, 

an observed release can be established using water, sediment, or benthic samples. 

It should be noted that the analytical results of surface water samples, cited by McGrath North, do not 

demonstrate any error in the analysis of the sediment samples used to establish an observed release at this 

site. 

Therefore, a significant increase in hazardous substance concentration was correctly identified and there 

is no change to the HRS Site score or the decision to place the Site on the NPL. 

3.9 Observed Release by Chemical Analysis - Attribution 

Comment: McGrath North questioned attribution at the Wright Chemical site. McGrath North asserted 

that any connection of the Wright Chemical Corporation site to Livingston Creek is an incomplete chain. 

McGrath North expressed its belief that the observed contamination is widespread in the river basin and is 

not specific to Livingston Creek. 

Response: The significant increases in metal concentrations in release samples (i.e., arsenic, cadmium, 

copper, lead, and zinc) were correctly attributed to the release from the Wright Chemical Corporation site. 

HRS Section 2.3, Likelihood of release, presents the attribution requirement to establish an observed 

release by chemical analysis: 

 10 
Wright Chemical Corporation Listing Support Document March 2011 

The minimum standard to establish an observed release by chemical analysis is analytical 

evidence of a hazardous substance in the media significantly above the background level. 

Further, some portion of the release must be attributable to the site [Emphasis 

added]. 

Further, HRS Section 4.1.2.1.1, Observed release, contains the directions used to establish an observed 

release to the surface water migration pathway. It states in part: 

Establish an observed release to surface water for a watershed by demonstrating that the 

site has released a hazardous substance to the surface water in the watershed. . . . 

• Chemical analysis: 

- Analysis of surface water, benthic, or sediment samples indicates that the 

concentration of hazardous substance(s) has increased significantly 

above the background concentration for the site for that type of sample 

(see section 2.3). 

- Some portion of the significant increase must be attributable to the 

site to establish the observed release [Emphasis added], except: when 

the site itself consists of contaminated sediments with no identified 

source, no separate attribution is required.

As explained in this response, it is sufficient to attribute some portion of the release to a site when the 

observed release substances are associated with a site source and no other facilities are the cause of the 

significant increase of hazardous substances. 

Pages 31 and 32 of the HRS documentation record at proposal under the heading, Attribution, presented 

the rationale for attributing the observed release of contaminants to the source (i.e., Source 1 - 

contaminated soil) associated with the Wright Chemical Corporation site: 

The Wright Chemical Corp site was a fertilizer and sulfuric acid manufacturing facility 

founded in 1883 (Ref. 4 pp. 397, 401). The original Acme plant was a lead-lined 

“chamber-process” plant that thermally extracted sulfur from pyrite (Ref. 4 pp. 109). 

Sanborn Fire Insurance Maps dated from 1898 and 1910 confirm that “Lead Acid 

Chambers” were previously present on the property where Source 1 has been identified 

(Ref. 4 pp. 173-179; Fig. 3). 

Denuded, magenta-colored soil characteristic of former lead chamber sulfuric acid 

manufacturing facilities (Ref. 4 pp. 214-215) has been documented in the vicinity of the 

former process areas on the property (Ref. 8, pp. 1-8). This magenta colored soil 

typically contains lead in the 4,000 – 20,000 mg/kg range and depending on the raw 

materials used in the processes, it can also contain substantial amounts of other metals 

and contaminants (Ref. 4 p. 215). Source 1 has been documented to contain elevated 

concentrations of metals including arsenic, cadmium, copper, lead, and zinc (see Table 2 

of this HRS documentation record) (Ref. 4, pp. 34, 36, 57-59, 61-63; Fig. 4). 

 

Source 1 drains north, downgradient into Livingston Creek (Figs. 1, 4). Sediment 

samples taken from Livingston Creek directly downgradient from source 1 show elevated 

concentrations of metals analogous to those found in source 1 (Ref. 4, pp. 35-56, 87-93; 

Fig. 7). 

 11 
Wright Chemical Corporation Listing Support Document March 2011 

There are three current/former facilities/sites that are upgradient from this site – Hexion, 

Kaiser Agricultural, and Kaiser Acme Farmarket (Ref. 4, pp. 108, 109-110, 117; Ref. 9, 

1-12). There are two nearby facilities/sites that are downgradient from Wright Chemical 

– International Paper (aka Federal Paperboard) and Holtrachem (Ref. 4, p. 3, Figs. 5, 6). 

The neighboring Hexion facility was at one time owned and operated by the Wright 

Chemical Corp. The history of chemical manufacturing on this adjacent 20-acre Hexion 

parcel included formaldehyde, hexamine, chloropicrin, silicon compounds and 

pharmaceuticals. There is no history of work with metals (Ref. 4, pp. 9, 129, 397-404). 

One sample (WC-010-SD; Tables 3, 4) was collected downgradient of Hexion and up 

gradient from Livingston Creek. This sample documents any impact to Mill Creek that 

may have occurred from runoff from the Hexion site prior to it entering Livingston 

Creek. 

The archived Kaiser Agricultural Chemical site (NCD 980 842 470) adjacent to and south 

of the lead chamber properties was once part of Acme Chemical and was owned by 

Wright Chemical. This parcel housed the fertilizer portion of the operation, it was 

investigated under CERCLA, and was archived from CERCLA in 1989 (Ref, 4, p. 110, 

111). The former Kaiser Acme Farmarket (NCD 980 557 847) pesticide facility is about 

1⁄4 mile to the south. This facility was associated with chlorinated pesticide manufacturing 

from 1967 – 1971 and subsequently for pesticide retail sales. There is no evidence it had 

metal contamination (Ref. 9, pp. 1-12). 

To the north and across Livingston Creek is the 978-acre parcel owned by Federal Paper 

Board Co., Inc. (aka International Paper) (Ref. 4, p. 452.3; Fig. 5). Adjacent to and east 

of Federal Paper Board, bordering the Cape Fear River is the former Holtrachem (aka 

LCP Chemicals; Honeywell; Allied Signal) mercury cell chlor-alkali plant site (NCD 991 

278 631), currently owned by Honeywell International (Ref. 4, pp. 452.4, 452.5; Fig. 6). 

Both of these sites are downgradient from the Wright Chemical Corp site. There is some 

flow reversal on Livingston Creek (Ref. 10, pp. 1, 2); however, neither the Holtrachem 

nor the International Paper site are associated with any lead, arsenic, cadmium, copper, or 

zinc contamination (Ref. 8, p. 2). Holtrachem has high contamination with mercury and 

PCBs (Ref. 8, p. 2). 

As described in the HRS documentation record at proposal, at least part of the significant increase of 

hazardous substances found in sediment samples can be attributed to the Wright Chemical site. As 

explained in section 3.9.1 (Association with Site Source) of this support document and in HRS Section 

2.2.2, the contaminants for which a significant increase in concentrations was established were associated 

with Source 1, the contaminated soil. Additionally, the background samples were collected from various 

areas to document the presence or absence of other potential sources of contamination. Specifically, 

sediment samples WC-001-SD and WC-002-SD were collected from Livingston Creek at points 

upgradient of the PPE to document background conditions upgradient of Wright Chemical. Sediment 

sample WC-010-SD was taken from Mill Creek, which is downgradient of the PPE but upgradient of its 

confluence with Livingston Creek (see Figure 2 of this support document for sample locations). These 

samples document that the contamination in the release samples was not coming from other upgradient 

sources. Section 3.9.2 (Other Facilities) of this support document, explains that other downgradient 

facilities are also not the cause of the significant increase in hazardous substances in Livingston Creek. 

 12 
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Wright Chemical Corporation Listing Support Document March 2011 

McGrath North’s specific comments on attribution are addressed in the following subsections of this 

support document: 

• Section 3.9.1 Association with Site Source 

• Section 3.9.2 Other Facilities 

3.9.1 Association with Site Source 

Comment: McGrath North asserted that any connection of the Wright Chemical Corporation site to 

Livingston Creek is an incomplete chain. 

Response: McGrath North did not explain what is meant by “incomplete chain.” If McGrath North was 

implying that EPA has not demonstrated that the contaminants have moved from the source into surface 

water and then actually migrated to a fishery and been found in a food chain organism, the HRS does not 

require that this chain be demonstrated to attribute a release to the site. As quoted above in section 3.9 

(Observed Release by Chemical Analysis – Attribution) of this support document, HRS Section 2.3 only 

requires at least part of the significant increase in hazardous substances to have come from the site. The 

remainder of this section documents that the substances are associated with the Site source. Section 3.9.2 

(Other Facilities) of this support document explains that no other facilities in the area of the Site are 

documented as contributing to this release. 

The significant increases in metals (i.e., arsenic, cadmium, copper, lead, and zinc) were correctly 

attributed, at least in part, to the release from the Wright Chemical site. The contaminants associated with 

the observed release sediment samples are the same contaminants associated with the Wright Chemical 

site source. Additionally, as discussed below, the Wright Chemical site contains evidence of direct 

deposition of the contaminants into Livingston Creek. 

HRS Section 4.0.2, Surface water categories, states in part: 

For HRS purposes, classify surface water into four categories: rivers, lakes, oceans, and 

coastal tidal waters. 

Rivers include: 

• Perennially flowing waters from point of origin to the ocean or to coastal tidal 

waters, whichever comes first, and wetlands contiguous to these flowing waters. 

Section 2.2, Source Characterization, of the HRS documentation record at proposal documented 

association of hazardous substances with Source 1: 

The source is contaminated soil as defined by samples WC-011-SS, WC-012-SS and 

WC-013-SS documented in the Table 1. These samples were collected near the former 

lead chambers and in the area where both 1) waste materials were placed and 2) overland 

flow from the former lead/acid chambers on the facility was received (Ref. 8, p. 7; Fig. 

4). This area of denuded soil has a purplish/magenta coloration and appears fairly 

consistent between the three samples (Ref. 8, pp. 1, 3-5). This area remains unfenced and 

is outside any runoff control features. (Ref. 8, pp. 1, 3-5) It is accessible but there are no 

signs of recreation. (Ref. 8, pp. 1, 3-5) 

The source area was observed to consist of three contiguous subareas. These areas are, 

from south to north: Area a) an upland area of denuded soils where the former lead 

chambers had been located, Area b) a wooded slope covered at least in part with 

 14 
Wright Chemical Corporation Listing Support Document March 2011 

bulldozed material similar to that observed in the former lead chamber area a), and Area 

c) a lowland area of contaminated soils. Source soil sample WC-012-SS was collected 

from Area a) while source soil samples WC-011-SS and WC-013-SS were collected from 

Area c), which extends to the probable point of entry (PPE) into Livingston Creek, and 

coincides, generally, with an area classified as non-HRS qualifying wetland type PUBH 

(Ref. 8, p. 7; Fig. 4) 

The HRS documentation record at proposal on page 20 listed the contaminants associated with 

Source 1, which are antimony, arsenic, cadmium, copper, lead, manganese, mercury, nickel, 

silver, thallium, and zinc. Therefore, the contaminants found in the observed release samples are 

associated with Source 1. 

In addition, there is evidence of direct deposition of the observed release substances (arsenic, cadmium, 

copper, lead, and zinc) used to establish an observed release by chemical analysis into Livingston Creek. 

Discussion of this direct deposition into Livingston Creek has been added to the attribution discussion in 

the HRS documentation record at promulgation; this addition does not change the site score. As shown in 

Figure 4 of the HRS documentation record at proposal, samples WC-11-SS and WC-13-SS are located in 

a wetland contiguous to Livingston Creek. As discussed above, according to HRS Section 4.0.2 these 

wetlands are considered part of Livingston Creek; the location of these samples is also adjacent to the 

contaminated segment of the Creek. Therefore, this direct deposition demonstrates that hazardous 

substances have been released directly into the Creek and at least some portion of the significant increase 

is attributed to the Wright Chemical site. 

This comment has no effect on the HRS Site score or the decision to place the Site on the NPL. 

3.9.2 Other Facilities 

Comment: McGrath North raised several issues identifying other facilities that could be possible sources 

of the contamination in Livingston Creek, particularly when tidal influence is considered. McGrath North 

questioned attribution of the significant increase in the observed release contaminant concentrations to 

Wright Chemical given the existence of these other facilities in the area of the Wright Chemical 

Corporation site that could also be releasing contamination into Livingston Creek. 

McGrath North stated that Livingston Creek is subject to minor tidal influences, usually less than one 

foot. However, it asserted that the water shifts and the resulting water level could range in excess of six 

feet in response to extended rainfall in combination with wind shifts and the resulting water level in the 

Cape Fear River. 

Concerning other possible facilities contributing to the release, McGrath North stated that the HRS 

documentation record at proposal identifies the existence of three current/former facilities (i.e., Hexion, 

Kaiser Agriculture, and Kaiser Acme Farmarket) upgradient of the Site and two nearby facilities (i.e., 

International Paper, Holtrachem) downgradient of the Site. The issue that McGrath North raised 

addresses the attribution to the Wright Chemical site of contaminants detected in sediment sample WC006-SD, collected 2,750 feet downstream of the PPE. McGrath North pointed specifically to observed 

release sample WC-006-SD: it stated that the levels of arsenic, cadmium, and lead concentrations in the 

observed release sample are “higher than the levels in the swamp area closer to the source area.” 

McGrath North concluded that “this sample appears to be an anomaly and it is not clear where the 

contamination in this sample originated.” 

McGrath North asserted that aquatic biota samples in nearby streams also suggest the contamination in 

the Creek could have come from other sites. It stated that the ESI, the HRS documentation record, and 

 15 
Wright Chemical Corporation Listing Support Document March 2011 

other information indicate that clam and fish tissues sampled in 2004 showed that metals and pesticides 

exceeded their respective recommended concentrations. This claim referenced a published study report, 

Environmental Assessment of the Lower Cape Fear River System, 2003-2004, prepared by Dr. Michael A. 

Mallin, et al, dated October 2005. Chapter 4 of this report states that bottom dwelling fish and clams in 

Rockfish Creek, Livingston Creek, and Six Runs Creek showed levels unsafe for human consumption for 

arsenic, cadmium, mercury, and selenium. The location of the sampling point in the Livingston Creek for 

this study was 40 meters from the confluence with Cape Fear River. Due to the tidal nature of the surface 

water bodies in the area and the similar concentrations of contaminants in the three water bodies sampled, 

McGrath North stated that this study indicates that contamination is widespread within the river basin and 

is not specific to Livingston Creek. 

McGrath North also referred to e-mail correspondence with Dr. Michael Mallin, author of the study and a 

research professor with the University of North Carolina Wilmington, who stated, "I do not believe that 

Livingston Creek is the sole source of contamination; it is likely one of several sources." Dr. Mallin also 

stated that there is a coal-fired power plant 20 km downriver near Wilmington that potentially contributes 

various chemicals (Se, As, Hg) to the tidal river and airborne emissions from that plant and even power 

plants in the Piedmont may influence biota at that station (i.e., a surface water monitoring station located 

at Livingston Creek, 40 meters from its confluence with the Cape Fear River). Dr. Mallin also mentions a 

former industry (Holtrachem) upstream of Livingston Creek on the Cape Fear River that polluted the area 

with mercury for many years. 

Response: Sufficient information exists to indicate that at least part of the significant increase in the 

release substances, as defined in HRS Section 2.3 and explained in section 3.8 of this support document, 

does not originate from other facilities either upgradient or downgradient of the Wright Chemical site. 

Samples were collected in locations both upgradient and downgradient of the Wright Chemical site to 

document that other sites are not the entire cause of the significant increase in the observed release 

substances in the sediment samples. 

The samples identified as from background locations in the HRS documentation record at proposal (see 

section 3.8 of this support document and page 27 of the HRS documentation record at proposal) were 

collected upgradient and adjacent to the Wright Chemical site to screen out the possibility of releases 

from upgradient facilities. Sediment samples WC-001-SD and WC-002-SD were taken upgradient of the 

Wright Chemical site in Livingston Creek, and sediment samples WC-008-SD, WC-009-SD, and WC010-SD were collected on Mill Creek (tributary to Livingston Creek) adjacent to the Wright Chemical 

site. Any contamination from upgradient sources would be reflected in the contaminant concentrations in 

these background samples. Specifically, sediment samples WC-001-SD and WC-002-SD show that 

upgradient facilities of Kaiser Agricultural Chemical and Kaiser Acme Farmarket are not responsible for 

contamination found in the observed release samples, and sediment sample WC-010-SD similarly shows 

that the neighboring Hexion facility is also not responsible for the contamination found in the observed 

release samples. If contamination were coming from these other upgradient facilities, the background 

samples would have reflected the contamination. 

Although not identified as a background sample at proposal, sediment sample WC-007-SD was taken 

1200 feet downgradient of the most distant downgradient observed release sample from the Wright 

Chemical source (sediment sample WC-006-SD) (see Figure 2 of this support document for sample 

locations). Therefore, sample WC-007-SD can be used to screen out the possibility that potential 

contaminants migrated upgradient by tidal influence. If contaminants were migrating upgradient due to 

tidal flow, concentrations of the contaminants due to migration would be reflected in sample WC-007-SD. 

If this sample were used as a background sample, the same observed releases would be identified as those 

identified when the upgradient background samples were used. The concentrations of the observed 

 16 
Wright Chemical Corporation Listing Support Document March 2011 

release substances -- arsenic, cadmium, copper, lead, and zinc (see Table 6 of the HRS documentation 

record at proposal) -- are actually lower in sample WC-007-SD than in the upgradient background 

samples (see Table 4 of the HRS documentation record at proposal). Therefore, if WC-007-SD were used 

to establish a background level for contamination migrating upgradient during tidal reversal, the observed 

release criteria would still be met in the three samples used to establish the observed release at proposal 

(WC-003-SD, WC-013-SD, WC-006-SD). For example, the copper concentration in sample WC-007-SD 

was 22 mg/kg. When this concentration is compared to the levels of copper in samples WC-003-SD, 

WC-013-SD, and WC-006-SD, which are 155, 122, and 631 mg/kg, respectively, a significant increase is 

identified according to HRS Table 2.3. In other words, if sample WC-007-SD had been identified as a 

background sample, the concentrations of contaminants in the observed release samples would be 

significantly greater and the observed release would still be established. 

Regarding McGrath North’s comment that the contaminant levels in sample WC-006-SD are higher than 

samples taken closer to Source 1, the higher contaminant levels do not demonstrate that the contamination 

in sample WC-006-SD is not attributable at least in part to Wright Chemical. This contamination is 

considered attributable at least in part to Wright Chemical because as explained above: 1) the observed 

release contaminants are all associated with Source 1; 2) the observed release contaminants are not 

thought to come from downgradient sources because sample WC-007-SD contains contaminant levels 

below three times background concentrations and effectively screens out this possibility; 3) International 

Paper and Holtrachem operations are not associated with all of the contaminants found in sample WC006-SD; and 4) there are no other known sources of contamination entering Livingston Creek between the 

PPE and sample WC-006-SD. 

Thus, although there is potential for tidal influence to reach Livingston Creek, the samples identified as 

background samples and sample WC-007-SD show that the significant contamination increases in the 

observed release samples are not originating from other facilities. 

In addition, there is no evidence that other sites have released several of the observed release 

contaminants (arsenic, cadmium, copper, lead, and zinc), and McGrath North did not provide any data 

showing that other facilities are associated with the observed release contaminants at the observed release 

sample locations. Further, in researching this issue, no rationale for associating the observed release 

contaminants with other nearby facilities could be found. The table below identifies the relative locations 

of the surrounding facilities as shown in Table 1 of this support document (see Figure 2 of this support 

document for sample locations). 

Table 1: Relative Location of Surrounding Facilities 

Company Direction from Wright 

Chemical site 

Kaiser Agricultural 

Chemical 

Upgradient 

Kaiser Acme Farmarket Upgradient 

Hexion Upgradient of one of the 

three observed release 

samples 

Holtrachem Downgradient 

International Paper Downgradient 

With respect to McGrath North's comments regarding the published study (Environmental Assessment of 

the Lower Cape Fear River System, 2003-2004) and Dr. Mallin's e-mail correspondence regarding other 

sources in the area identifying that there are other facilities in the lower Cape Fear River that could be the 

 17 
Wright Chemical Corporation Listing Support Document March 2011 

cause of contamination in Livingston Creek, the HRS score is not dependent on identifying the sources of 

contamination at the sampling point referred to in Dr. Mallin’s study. The HRS score is based only on 

contamination from sample WC-003-SD to sample WC-006-SD being attributable to the Wright 

Chemical site. The contamination at the sample point utilized in Dr. Mallin's study (i.e., 40 meters above 

the confluence of Livingston Creek and Cape Fear River) is not attributed to the Wright Chemical site. 

This comment has no effect on the HRS Site score or the decision to place the Site on the NPL. 

3.10 Waste Characteristics 

3.10.1 Waste Quantity 

Comment: McGrath North commented on the dimension of Source 1. It stated that preliminary soil 

borings indicate that the thickness of the magenta stained soil is less than two feet. 

Response: A waste quantity of “greater than 0” was assigned to Source 1 in accordance with the HRS. 

The dimensions of a source can be used in determining a volume estimate for establishing the HRS source 

and pathway waste quantity factor. However, in this case, volume was not used in this estimation due to 

the lack of information regarding the accuracy of the estimate that the contamination is less than two feet 

below surface throughout the source and that the contamination is limited to areas of visible stain. 

The estimate of hazardous waste quantity for Source 1 and for the surface water pathway was developed 

in accordance with HRS requirements.HRS Section 2.4.2, Hazardous Waste Quantity, states: 

Evaluate the hazardous waste quantity factor by first assigning each source (or area of 

observed contamination) a source hazardous waste quantity value as specified below. 

Sum these values to obtain the hazardous waste quantity factor value for the pathway 

being evaluated. 

HRS Section 2.4.2.1, Source hazardous waste quantity, states: 

For each of the three migration pathways, assign a source hazardous waste quantity value 

to each source (including the unallocated source) having a containment factor value 

greater than 0 for the pathway being evaluated. Consider the unallocated source to have a 

containment factor value greater than 0 for each migration pathway. 

. . . . 

For all pathways, evaluate source hazardous waste quantity using the following four 

measures in the following hierarchy: 

• Hazardous constituent quantity [Tier A] 

• Hazardous wastestream quantity [Tier B] 

• Volume [Tier C] 

• Area [Tier D] 

For the hazardous constituent quantity, the total mass of CERCLA hazardous substances allocated to the 

source has not been documented, thus the use of Tier A was not applicable in determining hazardous 

waste quantity. In addition, there was not adequate information to calculate Tier B (Hazardous 

wastestream quantity) or Tier C (Volume). Regarding a volume estimate, HRS Section 2.4.2.1.3, 

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Wright Chemical Corporation Listing Support Document March 2011 

Volume, states that if the volume cannot be determined, assign the source a value of 0 for the volume 

measure and proceed to HRS Section 2.4.2.1.4, Area, which states:

Evaluate the area measure using the area of the source (or the area of the area of observed 

contamination). Based on this area, designated as A, assign a value to the area measure 

as follows: 

• For the migration pathways, assign the source a value for area using the 

appropriate Tier D equation of table 2-5 

Page 21 of the HRS documentation record at proposal described how the hazardous waste quantity for 

Source 1 was established using an estimated area of the source. It stated: 

Volume - Sufficient evidence does not exist to evaluate Volume 

Area - Three points were collected in the former lead chamber / surface impoundment 

area; the area of contaminated soil is determined to be >0 (Ref. 4, pp. 108, 109, 115-117, 

120, 128, 161, 173-179, 180-182. 186, Figure 3) 

Area assigned value (Ref. 1, Table 2-5) = A/34,000 = >0

A volume estimate was not evaluated because the information provided does not support that the 

contaminated soil is consistently less than two feet in depth across the entire source area. Although there 

are points of contaminated soil, the exact extent of the contamination based on the limited sampling is not 

known either vertically or horizontally. Therefore, an estimated area of "unknown but >0" was evaluated 

for Source 1 (i.e., contaminated soil). This area estimate is the lowest value assignable and is likely an 

underestimate of the actual area of contaminated soil. For example, in McGrath North’s attachment (i.e., 

Figure 3 - Approximate Area of Contamination, prepared by Shields Engineering Inc., April 2010), the 

area of contaminated soil was delineated to be approximately 6-acres (see section 3.2 of this support 

document). If the actual area of contaminated soil were assigned a larger area value, it could only add to 

the site score as the site score could only increase as the waste quantity increases. 

Even if McGrath North's estimate of 6 acres of contaminated soil at a maximum depth of two feet were 

used to evaluate Tier C (Volume), the HRS site score would remain unchanged. This estimate would 

result in 522,720 ft3

 (43,560 ft2 per acre x 6 acres x 2 feet in depth) which results in 19,360 yd3 (522,720 

ft3

 / 27). Table 2-5 of the HRS states that the volume is to be divided into 2,500 (i.e., V/2,500), which 

results in a source hazardous waste quantity of 7.744 using the volume estimate. This value results in a 

pathway hazardous waste quantity factor value of 1 from HRS Table 2-6; however, since targets are 

subject to Level II concentrations for this site, the pathway waste quantity factor value of 100 applies. 

This is the same pathway hazardous waste quantity factor value assigned in the HRS documentation 

record at proposal based on a waste quantity estimate of >0 (see page 39 of the HRS documentation 

record at proposal). 

As discussed above, the hazardous waste quantity for Source 1 and for the surface water pathway at 

proposal was developed in accordance with HRS requirements. McGrath North's statement of 

preliminary soil borings indicating a thickness of the magenta stained soil less than two feet has no impact 

on the HRS evaluation. 

This comment has no effect on the HRS Site score or the decision to place the Site on the NPL. 

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Wright Chemical Corporation Listing Support Document March 2011 

3.10.2 Eligible Hazardous Substances 

McGrath North questioned the inclusion of cadmium in evaluating the waste characteristics associated 

with Source 1. McGrath North stated that the subject of this action is arsenic and lead contamination 

generated by the Acme Manufacturing Company and Wright Chemical Corporation from the operation of 

a lead chamber acid plant that began operation in 1883. McGrath North stated that the target of the 

proposed listing of the Wright Chemical Corporation site is the contamination associated with the former 

lead chamber sulfuric acid manufacturing plant and that cleanups of similar acid plants have been driven 

by the contaminants arsenic, lead, and low pH. McGrath North further stated that the ESI determined low 

concentrations of cadmium present in soil and sediments. McGrath North questioned the validity of HRS 

scoring using the minor site contaminant cadmium to evaluate the Human Food Chain Threat. McGrath 

North stated that cadmium is not a contaminant associated with the former acid plant and that the Human 

Food Chain Threat should have been evaluated using arsenic and lead, as these substances have been used 

to evaluate similar sites. 

Response: Hazardous substances, including cadmium were associated with Source 1 at the Wright 

Chemical Corporation site according to the HRS. 

HRS Section 1.1, Definitions, states: 

Source: Any area where a hazardous substance has been deposited, stored, disposed, or 

placed, plus those soils that have become contaminated from migration of a hazardous 

substance. ... 

HRS Section 2.2.2, Identify hazardous substances associated with a source, states: 

For each of the three migration pathways, consider those hazardous substances 

documented in a source (for example, by sampling, labels, manifests, oral or written 

statements) to be associated with that source when evaluating each pathway. In some 

instances, a hazardous substance can be documented as being present at a site (for 

example, by labels, manifests, oral or written statements), but the specific source(s) 

containing that hazardous substance cannot be documented. For the three migration 

pathways, in those instances when the specific source(s) cannot be documented for a 

hazardous substance, consider the hazardous substance to be present in each source at the 

site, except sources for which definitive information indicates that the hazardous 

substance was not or could not be present.. . . . 

Further, HRS Section 2.2.3, Identify hazardous substances available to a pathway, states:

In evaluating each migration pathway, consider the following hazardous substances 

available to migrate from the sources at the site to the pathway: 

• Ground water migration..... 

• Surface water migration—overland/flood component. 

- Hazardous substances that meet the criteria for an observed 

release to surface water in the watershed being evaluated. 

- All hazardous substances associated with a source with a surface 

water containment factor value greater than 0 for the watershed 

(see sections 4.1.2.1.2.1.1 and 4.1.2.1.2.2.1).... 

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Wright Chemical Corporation Listing Support Document March 2011 

Table 2 on page 19 of the HRS documentation record at proposal presented the contaminants and 

corresponding concentrations from Source 1 soil samples and the background soil sample. This table is 

shown below. 

 

Table 2. Source Soil and Background Soil Results 

Units 

mg/kg CRQL WC-011-SS WC-012-SS WC-013-SS 

WC-014-SS* 

(Background) 

(Ref. 5) 

Ref. 4, pp. 34, 

36, 57, 

Ref. 4, pp. 34, 

36, 59 

Ref. 4, pp. 34, 

36, 61, 62 

Ref. 4, pp. 34, 

36, 63 

Antimony** 6 69 J [34.8] 63 J [31.8] 86 J [43.4] 

 8.3 UJ

 (8.3 U)

Arsenic** 1 430 J [247] 700 J [402] 900 J [517] 1.4 J*

Cadmium 0.5 42 31 40 0.69 U

Copper** 2.5 210 J [172] 720 J [590] 890 J [730] 1.9 J* (3.5 U)

Lead** 1 

3500 J 

[2430]

7800 J 

[5417]

10000 J 

[6944] 16 J [23]

Manganese 1.5 32 27 27 8.9

Mercury 0.1 2.4 2.4 35 

0.056 J* (0.50 

U)

Nickel 4 20 17 19 1.9 J* (5.5 U)

Silver 1 18 29 43 1.4 U

Thallium 2.5 16 22 28 3.5 U

Zinc 6 7500 4700 6700 14 J

J = estimated value 

“U” indicates non-detect. The number adjacent to the “U” or inside () is the MRL. 

[ ] provides the adjusted value for the estimated (J’d) value as adjusted for bias (Ref. 4, pp. 266 - 283). 

*( ) = Minimum Reporting Limit (MRL) is shown in parentheses when a trace value is reported below the 

MRL. The MRL is the analyte concentration which corresponds to the lowest quantitative point on the 

calibration curve or the lowest demonstrated level of acceptable quantitation (Ref. 4, p. 36). 

Trace levels below reporting limits are treated as non-detect (Ref. 1, Table 2-3; Ref. 4, p. 269). 

**Flagging of data in the data reports (Ref. 4, pp 37 – 86) is inconsistent with statements in the data report 

(Ref. 4, pp. 34, 68). Generally, the narrative indicates some data should be J-qualified while data sheets did 

not show a J. Where a conflict appeared, the data was treated as J’d and subsequently adjusted as 

appropriate. Data were adjusted per “Using Qualified Data to Document an Observed Release and 

Observed Contamination”, to illustrate the relative increase of hazardous substance concentrations of 

background levels (Ref. 4, pp. 266-283). This is a conservative approach. 

**Arsenic and copper results are J’d due to high bias (Ref. 4, p. 34). Background is not adjusted; 

source/release results are adjusted downward by correction factor of 1.74 for arsenic and 1.22 for copper 

(Ref. 4, pp. 270, 283). Antimony and lead results are J’d due to uncertain bias. Because matrix spike 

sample recovery for antimony and lead were low, and because performance evaluation sample recovery 

were “action high” (Ref. 4, p. 34), data was adjusted based on uncertain bias (Ref. 4, pp. 34, 270, 273, 283). 

Background is adjusted upward and source/release results are adjusted downward by correction factor of 

1.98 for antimony and 1.44 for lead (Ref. 4, pp. 270, 283). 

BOLD = Observed contamination, which is greater than or equal to 3 times background when detected in 

background, or greater than background quantitation limit (aka MRL) and CRQL if background is nondetect (Ref. 1, Table 2-3; Ref. 4, p. 266). Note that source samples were compared to background soil 

sample in Table 2. 

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Wright Chemical Corporation Listing Support Document March 2011 

Table 2, above, documents that the soils in Source 1 came to be contaminated by demonstrating the level 

of several hazardous substances, including cadmium are present in the soil significantly above 

background levels and not just present at natural levels. Table 2 shows that Source 1 soil samples WC011-SS, WC-012-SS, and WC-013-SS all contain concentrations of contaminants that are above three 

times the background level found in sample WC-014-SS. The analytical data indicates that in addition to 

lead and arsenic, antimony, cadmium, copper, manganese, mercury, nickel, silver, thallium, and zinc were 

detected at concentrations significantly greater than concentrations of these substances detected in the 

background soil sample. Cadmium was detected in three source samples at concentrations ranging from 

31 to 42 mg/kg, which are significantly greater than detected in the background soil sample. Therefore, 

the association of all the metals, including cadmium, are properly associated with the contaminated soils 

and included in the evaluation of the Human Food Chain Threat. 

This comment has no effect on the HRS Site score or the decision to place the Site on the NPL. 

3.10.3 Assignment of Bioaccumulation Factor Values 

Comment: McGrath North stated that a freshwater swamp, influenced by Livingston Creek, is located 

immediately adjacent to the Site. 

Response: The salinity of Livingston Creek is used in determining the bioaccumulation factor value for 

the site. Upon review of the assignment of these values, the bioaccumulation factor values for each 

substance has been revised in the HRS documentation record at promulgation to use the appropriate 

bioaccumulation potential factor value for the human food chain threat in accordance with the provisions 

of the HRS. 

HRS Section 4.1.3.2.1.3, Bioaccumulation potential, directs the assignment of the bioaccumulation factor 

value: 

.... 

• If BCF data are available for both fresh water and salt water for the hazardous substance, use the 

BCF data that correspond to the type of water body (that is, fresh water or salt water) in which the 

fisheries are located to assign the bioaccumulation potential factor value to the hazardous 

substance. 

Further, HRS Section 4.1.3.2.1.4, Calculation of toxicity/persistence/bioaccumulation factor value, 

directs which value is to be used in scoring the Site: 

Assign each hazardous substance a toxicity/persistence factor value from table 4–12, 

based on the values assigned to the hazardous substance for the toxicity and persistence 

factors. Then assign each hazardous substance a toxicity/persistence/bioaccumulation 

factor value from table 4–16, based on the values assigned for the toxicity/persistence and 

bioaccumulation potential factors. Use the hazardous substance with the highest 

toxicity/persistence/bioaccumulation factor value for the watershed to assign the value to 

this factor. Enter this value in table 4–1. 

Section 4.1.3.2.1 (Toxicity/Persistence/Bioaccumulation) on pages 33-34 of the HRS documentation 

record at proposal, presented the bioaccumulation factor values and resulting Toxicity/Persistence/ 

Bioaccumulation Potential Factor values (T/P/BPFV) for each of the hazardous substances associated 

with Source 1, and provided the citation to the source of the assigned values: 

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Wright Chemical Corporation Listing Support Document March 2011 

The HRS instructs to evaluate the waste characteristics factor category based on two 

factors: toxicity/persistence and hazardous waste quantity. And, to evaluate only those 

hazardous substances that are available to migrate from the sources at the property to 

surface water in the watershed via the overland/flood hazardous substance migration path 

for the watershed. Such hazardous substances include hazardous substances that meet the 

criteria for an observed release to surface water in the watershed, and all hazardous 

substances associated with a source that has a surface water containment factor value 

greater than 0 for the watershed (Ref. 1, Section 4.1.2.2, also see sections 2.2.2, 2.2.3, 

4.1.2.1.2.1.1, and 4.1.2.1.2.2.1). Tables 7 and 8 of this HRS documentation record 

present those substances documented in the observed release to the fishery, and those 

substances documented in the source with a containment factor value greater than 0. 

As discussed above, Livingston Creek (3 miles) and the first 7 1⁄2 miles in the Cape Fear 

River is fresh, and the last 4 1/2 miles of the surface water pathway is brackish/salt. (See 

discussion in 4.1.1.1 above; Ref. 4, pp. 296, 300, 309). 

Table 7. Source 1 Contaminants Documented in Observed Release to Sediment in the Fishery 

Hazardous 

Substance 

Tox. 

Factor 

value 

PF# BPFV* 

Fresh 

Food** 

BPFV* 

Salt 

Food** 

T/P value 

(Ref. 1, Table 

4-12) 

T/P/BPFV 

(fresh) (Ref. 1, 

Table 4-16) 

T/P/BPFV (salt) 

(Ref. 1, Table 4-

16) 

Arsenic 10,000 1 5 500 10,000 5 x 10 E4 5 x 10 E6 

Cadmium 10,000 1 5,000 50,000 10,000 5 x 10 E7 5 x 10 E8 

Copper 0 1 500 50,000 0 0 0 

Lead 10,000 1 5 5,000 10,000 5 x 10 E4 5 x 10 E7 

Zinc 10 1 5 50,000 10 50 5 x 10 E5 

Table 8. Source 1 Contaminants Documented in Source with Containment Factor of 10, not 

documented in Observed Release to Fishery Sediment 

Hazardous 

Substance 

Tox. 

Factor 

value 

PF# BPFV* 

Fresh 

Food** 

BPFV* 

Salt 

Food** 

T/P value 

(Ref. 1, 

Table 4-12)

T/P/BPFV 

(fresh) (Ref. 1, 

Table 4-16) 

T/P/BPFV (salt) 

(Ref. 1, Table 4-

16) 

Antimony 10,000 1 5 5 10,000 5 x 10 E4 5 x 10 E4 

Manganese 10,000 1 50,000 50,000 10,000 5 x 10 E8 5 x 10 E8 

Mercury 10,000 1 50,000 50,000 10,000 5 x 10 E8 5 x 10 E8 

Nickel 10,000 1 0.5 500 10,000 5 x 10 E3 5 x 10 E6 

Silver 100 1 50 50,000 100 5 x 10 E3 5 x 10 E6 

Thallium 100 1 500 50 100 5 x 10 E4 5 x 10 E3 

T/P/BPFV = Toxicity/Persistence/Bioaccumulation Potential Factor (Ref. 1, Table 4-16) **Ref. 2, 

Appendix BI, pp. 1-15 

BPFV = Bioaccumulation Potential Factor Value 

#

PF = Persistence Factor Value, Ref. 1, Section 4.1.3.2.1.2; Ref. 2 

*Ref. 1, Section 4.1.3.2.1.3; Ref. 2. 

In the HRS documentation record at proposal, the higher of the saltwater and freshwater Bioaccumulation 

Potential Factor Values (BPFVs) was assigned in evaluation of waste characteristics. Therefore, at 

proposal the highest Toxicity/Persistence Bioaccumulation Potential Factor Values (T/P/BPFV) were for 

cadmium, manganese, and mercury (i.e., 5 x 10 E8). However, since the human food chain fishery being 

evaluated is located in a freshwater portion of Livingston Creek the BPFVs should have only included 

those values for freshwater (HRS documentation record page 24). Therefore, cadmium should have a 

T/P/BPFV of 5 x 10 E7 (fresh) instead of 5 x 10 E8 (salt) as listed in the HRS documentation record at 

proposal. The HRS document record has been revised at promulgation to make this correction. 

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Wright Chemical Corporation Listing Support Document March 2011 

This change has no effect on the HRS score for the Site. The HRS states in Section 4.1.3.2.1.4, to use the 

factor value having the highest combined T/P/BPFV. In this case for freshwater, both Manganese and 

Mercury have the highest possible T/P/BPFVs of 5 x 10 E8, the same value used at proposal. 

 

This comment has no effect on the HRS Site score or the decision to place the Site on the NPL. 

3.10.4 Containment 

Comment: McGrath North challenged the identification of a lack of containment for Source 1 by stating 

that arsenic and lead contaminated soils should be prevented from migrating off site; however, the present 

situation is stable and a cleanup is not time critical. McGrath North also stated that as seen on Figure 3, 

the probable extent of contamination can be fairly readily seen and that contamination does not appear to 

be migrating to the surrounding community. 

Response: The containment value for Source 1 was correctly assigned in the evaluation of the Site. HRS 

Section 4.1.2.1.2.1.1 states: 

HRS Table 4-2 lists the Containment Factor Values for the Surface Water Pathway: 

Source Assigned value

All Sources (Except Surface Impoundments, Land Treatment, Containers, and Tanks) 

Evidence of hazardous substance migration from source area (i.e., source area includes 

source and any associated containment structures). 

 

No evidence of hazardous substance migration from source area and: 

(a) Neither of the following present: (1) maintained engineered cover, or (2) functioning 

and maintained run-on control system and runoff management 

system 

(b) Any one of the two items in (a) present 

(c) Any two of the following present: (1) maintained engineered cover, or (2) 

functioning and maintained run-on control system and runoff management 

system, or (3) liner with functioning leachate collection and removal system 

immediately above liner 

(d) All items in (c) present 

(e) All items in (c) present, plus no bulk or non-containerized liquids nor materials 

containing free liquids deposited in source area. 

No evidence of hazardous substance migration from source area, double liner with 

functioning leachate collection and removal system above and between liners, and: 

(f) Only one of the following deficiencies present in containment: (1) bulk or 

noncontainerized liquids or materials containing free liquids deposited in source 

area, or (2) no or nonfunctioning or nonmaintained run-on control system and 

runoff management system, or (3) no or nonmaintained engineered cover 

(g) None of the deficiencies in (f) present. 

Source area inside or under maintained intact structure that provides protection from 

precipitation so that neither runoff nor leachate is generated, liquids or materials 

containing free liquids not deposited in source area, and functioning and maintained runon 

control present 

10 

10 

9 

7 

5 

3 

3 

0 

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Wright Chemical Corporation Listing Support Document March 2011 

Page 16 of the HRS documentation record at proposal documented the assignment of the containment 

value for this source. The containment value was assigned from Table 4-2 of the HRS. Specifically, a 

containment value of 10 for Source 1 was assigned based on the following: 

• Contaminated soil is outside any controlled runoff feature and is available for continuous and 

ongoing overland flow (Ref. 1, Table 4-2; Ref. 8, pp 1. 3-5). 

• An observed release of site contaminants to Livingston Creek (Ref. 1; Ref. 4, pp. 34, 36, 41, 47, 

65, 66; Table 4-9) 

Since no containment features are present at the Site and there is evidence of hazardous substance 

migration from the Site, the containment value of 10 for Source 1 was correctly assigned in accordance 

with the HRS. 

This comment has no effect on the HRS Site score or the decision to place the Site on the NPL. 

3.11 Targets 

3.11.1 Presence of Private Receptors 

Comment: McGrath North questioned the presence of targets in the vicinity of the Wright Chemical 

Corporation site. McGrath North stated that in spite of being in a rural part of the county, the Site is 

surrounded by former or current industrial facilities. McGrath North further stated that there are no 

potential private receptors that could be affected by releases at the Wright Chemical Corporation Site. 

Response: It is unclear what McGrath North means by the term "private receptors"; however, the only 

target (receptor) included in the HRS evaluation was a human food chain fishery. The presence of a 

human food chain target (i.e., receptor) in the Livingston Creek fishery was properly established 

according to the HRS as an eligible target. The HRS makes no distinction regarding “private” receptors. 

The HRS identifies that human food chain fisheries are eligible targets. HRS Section 4.1.3.3, Human 

food chain threat - targets, states: 

Evaluate two target factors for each watershed: food chain individual and population. For 

both factors, determine whether the target fisheries are subject to actual or potential 

human food chain contamination. 

Further, HRS Section 4.1.3.3.1, Food chain individual, states:

Evaluate the food chain individual factor based on the fisheries (or portions of fisheries) 

within the target distance limit for the watershed. ... 

HRS Section 4.1.3.3.2, Population, states: 

Evaluate the population factor for the watershed based on three factors: Level I 

concentrations, Level II concentrations, and potential human food chain contamination. 

Determine which factor applies for a fishery (or portion of a fishery) as specified in 

section 4.1.3.3. 

4.1.3.3.2.1 Level I concentrations..... 

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Wright Chemical Corporation Listing Support Document March 2011 

4.1.3.3.2.2 Level II concentrations. Determine those fisheries (or portions of fisheries) 

within the watershed that are subject to Level II concentrations. Do not include any 

fisheries (or portions of fisheries) already counted under the Level I concentrations 

factor. 

Page 36 of the HRS documentation record at proposal under the title, Human Food Chain Threat – 

Targets, identified an eligible fishery target: 

Livingston Creek, from WC-001-SD upstream of Old Highway 87 until its 

confluence with the Cape Fear River is a fishery. Brim, bass and catfish are caught in 

the creek, and catches are cooked and consumed on the creek banks (Ref. 4, pp. 88, 

91, 531 – 533). 

Based on documentation that human food chain species are fished for consumption within Livingston 

Creek, a human food chain fishery was correctly identified as a target in the HRS documentation record at 

proposal. This fishery was correctly identified and used for scoring human food chain individual and 

population. 

This comment has no effect on the HRS site score or the decision to place the Site on the NPL. 

3.11.2 Zone of Contamination 

Comment: McGrath North questioned whether sediment sample WC-006-SD, which has concentrations 

higher than those in the swamp area close to the source area, is an observed release from the Wright 

Chemical site. McGrath North questioned the origin of the contamination at sample location WC-006-SD 

and whether it is part of the zone of contamination at the Wright Chemical site. 

Response: The zone of contamination for surface water was identified in accordance with the HRS and 

the targets within that zone were properly identified as actually contaminated. However, there was an 

error in the description of the Level II zone of contamination under the title "Food Chain Individual." 

The text of this section was revised, in the HRS documentation record at promulgation, to reflect that the 

Level II zone of contamination extends to sample WC-006-SD. 

Instructions for delineating the zone of contamination for a human food chain fishery are located in HRS 

Section 4.1.1.1, Definition of hazardous substance migration path for overland/flood migration 

component. It states that: 

The hazardous substance migration path includes both the overland segment and the inwater segment that hazardous substances would take as they migrate away from sources 

at the site: 

• Begin the overland segment at the source and proceed downgradient to the 

probable point of entry to surface water. 

• Begin the in-water segment at this probable point of entry. 

- For rivers, continue the in-water segment in the direction of flow 

(including any tidal flows) for the distance established by the target 

distance limit.... 

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Wright Chemical Corporation Listing Support Document March 2011 

HRS Section 4.1.1.2, Target distance limit, states: 

[t]he target distance limit defines the maximum distance over which targets are 

considered in evaluating the site. Determine a separate target distance limit for each 

watershed as follows: 

. . . 

• If there is an observed release from the site to the surface water in the watershed that 

is based on sampling, begin measuring the target distance limit for the watershed at 

the probable point of entry; extend the target distance limit either for 15 miles along 

the surface water or to the most distant sample point that meets the criteria for an 

observed release to that watershed, whichever is greater. 

In evaluating the site, include only surface water targets (for example, intakes, fisheries, 

sensitive environments) that are within or contiguous to the hazardous substance 

migration path and located, partially or wholly, at or between the probable point of entry 

and the target distance limit applicable to the watershed: 

. . . 

• Determine whether targets within or contiguous to the hazardous substance 

migration path are subject to actual or potential contamination as follows: 

- If a target is located, partially or wholly, either at or between the probable point 

of entry and any sampling point that meets the criteria for an observed release to 

the watershed or at a point that meets the criteria for an observed release by 

direct observation, evaluate that target as subject to actual contamination, except 

as otherwise specified for fisheries in section 4.1.3.3 and for wetlands in section 

4.1.4.3.1.1. If the actual contamination is based on direct observation, assign 

Level II to the actual contamination. However, if the actual contamination is 

based on samples, determine whether the actual contamination is at Level I or 

Level II concentrations as specified in sections 4.1.2.3, 4.1.3.3, and 4.1.4.3.1. 

- If a target is located, partially or wholly, within the target distance limit for the 

watershed, but not at or between the probable point of entry and any sampling 

point that meets the criteria for an observed release to the watershed, nor at a 

point that meets the criteria for an observed release by direct observation, 

evaluate it as subject to potential contamination. 

Thus, the HRS states to consider that targets are subject to actual contamination if they are between the 

probable point of entry (PPE) and the furthest downstream sample that meets observed release criteria 

(regardless of whether or not there are samples between these points that do not meet the criteria). HRS 

Section 4.1.3.3, Human food chain threat-targets, identifies further requirements for determining a human 

food chain fishery within the zone of contamination: 

Consider a fishery (or portion of a fishery) within the target distance limit of the 

watershed to be subject to actual human food chain contamination if any of the 

following apply: 

• A hazardous substance having a bioaccumulation potential factor value of 500 

or greater is present either in an observed release by direct observation to the 

watershed or in a surface water or sediment sample from the watershed at a level 

that meets the criteria for an observed release to the watershed from the site, and 

at least a portion of the fishery is within the boundaries of the observed release 

 27 
Wright Chemical Corporation Listing Support Document March 2011 

 28 

(that is, it is located either at the point of direct observation or at or between the 

probable point of entry and the most distant sampling point establishing the 

observed release). 

• The fishery is closed, and a hazardous substance for which the fishery has been 

closed has been documented in an observed release to the watershed from the 

site, and at least a portion of the fishery is within the boundaries of the observed 

release. 

• A hazardous substance is present in a tissue sample from an essentially sessile, 

benthic, human food chain organism from the watershed at a level that meets the 

criteria for an observed release to the watershed from the site, and at least a 

portion of the fishery is within the boundaries of the observed release. 

Page 36 of the HRS documentation record at proposal under the title, Food Chain Individual, stated: 

Level II contamination in Livingston Creek from the PPE downstream 250 feet to 

Sample WC-003-SD has been documented as part of a fishery. (Ref. 4, pp. 35, 70, 88, 

531-533, Fig. 4).

Page 37 of the HRS documentation record at proposal under the title, Level II Concentrations, stated: 

Arsenic, cadmium, copper, lead, and zinc contamination have been documented in source 

1 and in sediment in the fishery. The level of contaminants is summarized below: 

mg/kg WC-003-SD WC-013-SD WC-006-SD

Arsenic 31 J [17.8] 29 J [16.6] 320 J [183.9]

Cadmium 3.5 3.6 2.4 U, J

Copper 190 J [155] 150 J [122] 770 J [631]

Lead 520 J** [360] 430 J** [300] 1200 J** [830]

Zinc 660 780 380

The HRS documentation record has been revised at promulgation to show that the Level II zone of 

contamination extends to sample WC-006-SD. The revision of the description of the zone of 

contamination in the HRS documentation record at promulgation does not have an impact on the HRS 

score, as Level II concentrations were correctly scored at proposal as extending to sample WC-006-SD. 

4. Conclusion 

The original HRS score for this site was 48.03. Based on the above responses to public comments, the 

site score remains unchanged. The final scores for the Wright Chemical Corporation site are: 

Ground Water: NS 

Surface Water: 96.06 

Soil Exposure: NS 

Air Pathway: NS 

HRS Score: 48.03