Document ID: EPA_FRDOC_0001-26867
Agency: epa
Document Type: Notice
Title: National Oil and Hazardous Substances Pollution Contingency Plan: National Priorities List: Explanation of Significant Differences for the Del Norte County Pesticide Storage Area Superfund Site
Posted Date: 2021-05-19T04:00Z

[Federal Register Volume 86, Number 95 (Wednesday, May 19, 2021)]
[Notices]
[Pages 27081-27083]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-10511]

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ENVIRONMENTAL PROTECTION AGENCY

[FRL-10023-10-Region 9]

National Oil and Hazardous Substances Pollution Contingency Plan; 
National Priorities List: Explanation of Significant Differences for 
the Del Norte County Pesticide Storage Area Superfund Site

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of explanation of significant differences.

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SUMMARY: The U.S. Environmental Protection Agency (EPA) Region 9 is 
issuing an explanation of significant differences (ESD) for the Del 
Norte County Pesticide Storage Area Superfund Site (the Site), located 
at 2650 West Washington Boulevard in Crescent City, Del Norte County, 
California, and is notifying the public of

[[Page 27082]]

this undertaking. When significant but not fundamental changes are made 
to the scope, performance, or cost of a remedy after a final remedy has 
been adopted, Comprehensive Environmental Response, Compensation, and 
Liability Act (CERCLA) and the National Oil and Hazardous Substances 
Pollution Contingency Plan (NCP), require that the lead agency prepare 
an ESD. Because the Site's remaining contaminant of concern (COC) has 
reached drinking water standards, this ESD was issued to modify the 
remedy at the Site to remove the technical impracticability (TI) waiver 
for 1,2-dichloropropane (1,2-DCP) and reinstate the applicable or 
relevant and appropriate requirement (ARAR) for 1,2-DCP. In accordance 
with CERCLA, the EPA consulted with the support agency, the California 
Department of Toxic Substances Control (DTSC). DTSC provided written 
concurrence on the ESD. The Site was delisted from EPA's National 
Priorities List (NPL) in 2002, and this remedy modification does not 
impact EPA's determination that the Site remedy remains protective of 
human health and the environment, complies with federal and state 
requirements that were identified as applicable or relevant and 
appropriate to this remedial action, and is cost-effective.

DATES: The Final ESD became effective on April 14, 2021.

FOR FURTHER INFORMATION CONTACT: Cynthia Ruelas, Superfund Remedial 
Project Manager, EPA, Region 9 (SFD-7-1), 75 Hawthorne Street, San 
Francisco, CA 94105; telephone number: 415-972-3329; email address: 
ruelas.cynthia@epa.gov.

SUPPLEMENTARY INFORMATION:

I. Introduction

    Region 9 of the EPA announces the issuance of an ESD at the Del 
Norte County Pesticide Storage Area Superfund Site (Site). When 
significant, but not fundamental, changes are made to the scope, 
performance, or cost of a remedy after a final remedy has been adopted, 
CERCLA and the NCP require that the lead agency prepare an ESD pursuant 
to the NCP, 40 CFR 300.435(c)(2) and 300.825(a).
    Section II of this notice explains the purpose of an ESD. Section 
III discusses the process that the EPA has undertaken for this action. 
Section IV discusses the site and describes the basis for issuance of 
an ESD.

II. ESD Purpose

    EPA adopted this ESD to document a change to the selected remedy to 
remove a TI waiver for 1,2-DCP, adopt the maximum contaminant level 
(MCL) as the cleanup level, and describe how the Site has met that ARAR 
standard. Changes to a Selected Remedy described in a Record of 
Decision (ROD) are documented using one of the following documents, 
depending on the nature of the change: (1) A technical memorandum in 
the Administrative Record for an insignificant or minor change; (2) an 
ESD for a significant change; or (3) a ROD Amendment for a fundamental 
change. A significant change is defined as a change to a component of a 
remedy that does not fundamentally alter the overall cleanup approach. 
Because this remedy change updates the status of the Site TI Waiver and 
ARAR requirements and does not change the remedy approach, an ESD was 
deemed to be the appropriate document to record the changes to the ROD. 
An ESD provides a description of the nature of the significant change, 
summarizes the information that led to making the change, and affirms 
that the revised remedy complies with the NCP and the statutory 
requirements of CERCLA. In accordance with the ROD for the Site, the 
overall cleanup goal of the remediation, which is to protect public 
health from exposure to COCs, remains in place. The ROD for the Site is 
being modified so that remedy implementation can be refined and 
improved to reflect achievement of health protective cleanup levels.

III. ESD Process

    The following describes the general process that the EPA followed 
to prepare and issue the ESD.
    (1) The ESD identifies and discusses the significant differences 
between the remedy as presented in the ROD and subsequent decision 
documents and the change now proposed. It identifies the remedial 
action objectives (RAOs) of the remedy, which include a reinstated 
objective from the ROD to clean up contaminated groundwater to meet 
drinking water standards and enable beneficial use of the Site. The ESD 
also summarizes the scope and performance of the current and previous 
Site decision documents (the 1985 ROD, 1989 ESD, 2000 ROD Amendment, 
and 2021 ESD).
    (2) The ESD confirms that the Site remedy continues to meet ARARs 
(in compliance with the NCP, 40 CFR 300.430(f)(1)(ii)(B)(1) and (2)), 
satisfies Section 121 of CERCLA, 42 U.S.C. 9621, and remains protective 
of human health and the environment.
    (3) Before issuance of the ESD, the EPA as lead agency consulted 
with DTSC, the support agency, in accordance with the NCP, 40 CFR 
300.435(c)(2). The EPA provided DTSC the opportunity to comment on the 
ESD. DTSC concurred with the issuance of the ESD for the Site, and 
DTSC's concurrence memo is included as an attachment to the ESD.
    (4) The EPA Regional Administrator's designee approved and signed 
the ESD.
    (5) Concurrent with the publication of this notice of issuance of 
this ESD in the Federal Register, the EPA published a notice of 
availability and a brief description of the ESD in a major local 
newspaper of general circulation (as required by the NCP at 40 CFR 
300.435(c)(2)(i)(B)). A formal public comment period is not required 
for issuance of an ESD.
    (6) The ESD and supporting documents are available for public 
review in the Administrative Record file and information repository, 
pursuant to the NCP, 40 CFR 300.435(c)(2)(i)(A) and 300.825(a)(2).

IV. Basis for Issuance of an ESD

    The following information provides the EPA's basis for issuing the 
ESD for the Site.

Site Background and History

    The Site (CERCLIS ID #CAD000626176) is located at 2650 West 
Washington Boulevard in Crescent City, Del Norte County, California, 
and is an approximately 1-acre property consisting of 2 parcels. From 
1970 to 1981, the site served as a collection facility for pesticide 
storage containers used in local agricultural and forestry operations 
in Del Norte County. The facility was operated by the County, with 
approval from the North Coast Regional Water Quality Control Board 
(NCRWQCB), and was intended to serve as a county-wide collection point 
for interim or emergency storage of pesticide containers generated by 
local agricultural and forestry-related industries. Inspections 
conducted by the EPA and NCRWQCB in 1981 revealed violations of the 
Resource Conservation and Recovery Act (RCRA), and a failure to operate 
under the conditions previously agreed upon with the NCRWQCB. Shortly 
after receiving a Cleanup and Abatement Order from NCRWQCB, the County 
decided to close the facility. State and County sampling efforts 
revealed a variety of contaminants in the soil and groundwater at the 
Site. Due to lack of County funding to investigate the extent of 
contamination and develop a cleanup plan, the EPA placed the Site on 
the NPL in 1984.

[[Page 27083]]

Basis for Taking Action

    NCRWQCB conducted initial investigations at the Site and found that 
both the soil and groundwater were contaminated with various 
herbicides, pesticides, and volatile and semi-volatile organic 
compounds and chromium. The specific COCs identified were 1,2-DCP and 
2,4-dichlorophenoxyacetic acid (2,4-D). Soil contamination was detected 
to a depth of 15 feet but was contained to an on-site sump of 15 feet 
by 20 feet. At the time, the groundwater contaminant plume was 
estimated to extend approximately 170 feet to the southeast of the 
sump, in the direction of groundwater movement. If the contaminated 
aquifer were to be used as a drinking water supply, it would pose a 
significant health risk. Ingestion of these contaminants has been 
linked to increased cancer risk. Investigations indicated that elevated 
levels of chromium were also present at the Site.

Original Remedy Selection

    In 1985, the EPA selected a remedy in a ROD to address the soil and 
groundwater contamination at the Site. The major components of the 
Selected Remedy included: Excavation and off-site disposal of 
contaminated soils; extraction and treatment of groundwater through 
carbon adsorption and coagulation/filtration treatment; disposal of 
treated groundwater to the Crescent City Wastewater Treatment Plant; 
and groundwater monitoring.

Actions Taken Following ROD Issuance

    The 1989 ESD explained that because the chromium at the Site was 
determined to be naturally-occuring, it could not be remedied under 
CERCLA, pursuant to 42 U.S.C. 104(a)(3)(A). The ESD also documented and 
justified a change in the groundwater treatment method from carbon 
adsorption and coagulation/filtration to air sparging.
    The EPA issued a ROD Amendment in 2000 that revised the remedy, 
because the Site RAO of restoring the contaminated groundwater to the 
drinking water standard for 1,2-DCP could not be met, because no 
technology existed that was capable of reaching the 10 micrograms per 
liter ([micro]g/L) level set out in the ROD. Notably, this applied as 
well to the Maximum Contaminant Level (MCL) of 5 [micro]g/L that had 
since been adopted since the cleanup level had been selected for the 
Site. In light of the inability to reach these cleanup levels, the ROD 
Amendment's revised remedy instead sought to contain the groundwater 
contamination through natural attenuation and monitoring and prevent 
its use as drinking water for as long as contaminant concentrations 
exceeded drinking water quality standards. The ROD Amendment identified 
the new ARAR for 1,2-DCP (equivalent to the new MCL of 5 [micro]g/L); 
adopted a TI waiver of the newly identified ARAR for groundwater within 
the existing contaminated area where 1,2-DCP exceeded 5 [micro]g/L; and 
required semi-annual groundwater monitoring and the enactment of 
institutional controls (ICs) to prevent exposure to contaminated 
groundwater.
    In 2002, the EPA, DTSC, and Del Norte County entered into a Consent 
Decree, and in doing so, Del Norte County agreed to carry out and 
finance continued remediation efforts at the Site, including monitoring 
groundwater and implementing ICs in accordance with Site decision 
documents and plans. Also, in that same year, because all response 
actions required under CERCLA had been completed, except for ongoing 
operation and maintenance and Five-Year Reviews, following a 30-day 
public comment period, the EPA deleted the Site from the NPL.

Basis for ESD

    Nearly 20 years after issuance of the TI waiver for 1,2-DCP, 
groundwater data from the Site consistently demonstrate that 
concentrations of 1,2-DCP have significantly decreased and are now 
below the drinking water standard of 5 [micro]g/L. Given the 
effectiveness of natural attenuation in lowering concentrations of 1,2-
DCP in Site groundwater to meet the MCL, the TI waiver adopted in the 
2000 ROD Amendment is no longer necessary. Through this ESD, the EPA is 
removing the TI waiver for 1,2-DCP and reinstating the 1,2-DCP ARAR. 
The ESD also reinstates the original RAO that sought to clean up 
contaminated groundwater to meet drinking water standards. Cleanup 
under CERCLA is considered complete, although groundwater monitoring is 
currently ongoing at the Site under state oversight, and EPA plans to 
continue the Five-Year Review process as required until such time that 
groundwater attainment is formally achieved.

Enrique Manzanilla,
Director, Superfund Division, U.S. EPA, Region 9.
[FR Doc. 2021-10511 Filed 5-18-21; 8:45 am]
BILLING CODE 6560-50-P