PB98-963112
EPA 541-R98-044
September 1998
EPA Superfund
Explanation of Significant Difference
for the Record of Decision:
Ramapo Landfill
Ramapo, NY
11/26/1997
-------
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
-'.--.• REGION II
DATE:
N°V
l997
SUBJECT: Explanation of Significant Differences for the Ramapo Landfill SuperfUnd Site
FROM: Richard L. Caspe, P.E., Director
Emergency and Remedial Response Divisidfi
T0: Jeanne M. Fox •
Regional Administrator
Attached is an Explanation of Significant Differences (ESD) for the Ramapo Landfill Superfund site.
TheMarchSl, 1992 Record of Decision (ROD) called for, among other things, the installation of a
cap with an impermeable barrier only on the top (flat) portion of the Ramapo Landfill. In addition,
the ROD indicated that the landfill's side slopes would not require an impermeable barrier, unless
further study concluded that incorporating an impermeable barrier would result in a significantly more
effective remedy.
As a result of the studies called for in the ROD, it was determined that a landfill cover which included
an impermeable barrier on the side slopes of the landfill would be significantly more protective and
cost-effective than a cover without an impermeable barrier on the side slopes. The attached ESD
documents these findings.
Please indicate your approval of the ESD by signing below.
If you have any questions related to the ESD, please call me at extension 4390.
Attachment
Approved:
M. Fox
nal Administrator
Date
-------
Explanation of Significant Differences
RAMAPO LANDFILL SITE
Town of Ramapo
Rockland County, New York
EPA
Region 2
December 1997
INTRODUCTION
In accordance with the Comprehensive Environmental
Response, Compensation, -and Liability Act (CERCLA)
Section 117(c), and Section 300.435(c)(2)(i) of the National
Oil and Hazardous Substances Contingency Plan, if after the
Environmental Protection Agency (EPA) selects a remedial
action, there is a significant change with respect to that
action, an explanation of the significant differences and the
reasons such changes were made must be published.
The March 31, 1992 Record of Decision (ROD) called for,
among other things, the installation of a cap with an
impermeable barrier only on the top (flat) portion of the
Ramapo Landfill. In addition, the ROD indicated that the
landfill's side slopes would not require an impermeable
barrier, unless further study concluded that incorporating an
impermeable barrier would result in a significantly more
effective remedy.
As a result of the studies called for in the ROD, it was
determined that a landfill cover which included an
impermeable barrier on the side slopes of the landfill would
be significantly more protective and cost-effective than a
cover without an impermeable barrier on the side slopes.
The engineering design of the remedy was completed in
June 1994. The construction of the cover over the top and
the side slopes of the landfill was completed in May 1997.
This Explanation of Significant Differences (ESD) will
become part of the Administrative Record file for the site.
The entire Administrative Record for the site, which includes
the remedial investigation and feasibility study (RI/FS) report,
ROD, and other relevant documents are available for public
review at the following location:
Finkelstein Public Library
24 Chestnut Street
Spring Valley, New York
Hours: Mon.-Thur, 9:00 am - 9:00 pm
Fri., 9:00 am - 6:00 pm
Sat, 10:00 am - 5:00 pm
Sun., 12:00 Noon - 5:00 pm
and
Suffern Free Public Library
Washington and Maple Avenues
Suffem, New York
Hours: Mon.-Thur., 10:00 am - 9:00 pm
Fri.-Sat, 10:00 am - 5:00 pm
Sun., 1:00pm-5:00pm .
The Administrative Record file and other relevant reports and
documents are also available for public review at the EPA
Region II office at the following location:
U.S. Environmental Protection Agency
290 Broadway, 18th floor
New York, New York 10007
Hours: 9:00 am - 5:00 pm (Monday - Friday)
The difference from the selected remedy is not considered
by EPA or the New York State Department of Environmental
Conservation (NYSDEC) to be a fundamental alteration of
the remedy selected in the ROD. The remedy modification
increases the protectiveness of the action with respect to
human health and the environment, increases the cost-
effectiveness of the action, and complies with federal and
state requirements that were identified in the ROD.
SUMMARY OF SITE HISTORY, CONTAMINATION
PROBLEMS, AND SELECTED REMEDY
The Ramapo Landfill site is located on a 96-acre tract in the
Town of Ramapo, Rockland County, New York.
Approximately 50 acres of the site are covered with fill
material (the "landfill portion* of the site). The landfill portion
of the site is mounded into two major lobes (northern and
southern). Both landfill lobes consist of mixed refuse.
Substances reportedly disposed of in the landfill portion of
the site include industrial sludge and other wastes reportedly
from a pharmaceutical company, sewage sludge, municipal
refuse, asbestos, construction and demolition debris, yard
debris, paint sludge, and liquid wastes reportedly from a
paper company.
In 1971, the Rockland County Department of Health granted
a permit to the Town of Ramapo for the operation of the
sanitary landfill. Municipal waste was accepted in the landfill
until 1984. The Town of Ramapo continued to accept
construction and demolition debris at the site until 1989.
In September 1983, the Ramapo Landfill site was placed on
-------
page 2
the Superfund National Priorities List
Based upon the results of the RI/FS. on March 31, 1992, a
ROD was signed. The major components of the selected
remedy are as follows:
• Installation of a cap on the top of the landfill;
• Excavation and consolidation of contaminated soils
within the capped area;
• Installation of groundwater extraction wells to
supplement the existing leachate collection system;
• Collection and diversion of leachate seeps to the
leachate collection system;
• Conveyance of the collected leachate and
groundwater to a publicly-owned treatment works for
off-site treatment.
• Imposition of property deed restrictions to prevent
the installation of drinking water wells at the site and
restrict activities which could affect the integrity of
the cap;
• Performance of operation, maintenance, and long-
term monitoring activities; and
• Development of a contingency plan for rapid
implementation of measures to protect nearby
residents and users of groundwater if those
measures are determined to be necessary.
The ROD also stated that an impermeable barrier would be
placed on the landfill's side slopes if confirmatory studies
indicated that the remedy's overall effectiveness would be
significantly enhanced.
DESCRIPTION OF SIGNIFICANT DIFFERENCES AND
THE REASONS FOR THOSE DIFFERENCES
The confirmatory studies called for in the ROD indicated that
the exclusion of an impermeable barrier from the landfill cap
on the side slopes would result in increased infiltration of
rainfall through the cap. This would cause the generation of
greater quantities of contaminated groundwater than a
landfill cap with an impermeable barrier on the side slopes,
which would result in greater operational costs to collect and
treat a larger volume of contaminated groundwater and
leachate.
In addition, it was determined that either a thicker soil cover
or an impermeable barrier would be needed on the side
slopes to provide adequate control of landfill gases. The
impermeable barrier was found to be the less costly of the
two options.
Therefore, based upon the results of the confirmatory
studies, it was concluded that a cap with an impermeable
barrier on the landfill's side slopes would be more protective
and more cost-effective than a cap without an impermeable
barrier on the side slopes.
SUPPORT AGENCY COMMENTS
NYSDEC supports the change to the remedy due to its
environmental, public health, and technical advantages over
the remedy selected in the ROD.
AFFIRMATION OF STATUTORY DETERMINATIONS
EPA and NYSDEC believe that the modified remedy
increases the protectiveness of the action with respect to
human health and the environment, increases the cost-
effectiveness of the action, and complies with federal and
state requirements that are applicable or relevant and
appropriate to this remedial action. In addition, the remedy,
continues to utilize permanent solutions and alternative
treatment technologies to the maximum extent practicable
for this site.
PUBLIC PARTICIPATION ACTIVITIES
EPA and NYSDEC rely on public input to ensure that the
concerns of the community are considered. Towards this
end, EPA invites comments or questions related to this ESD.
Comments or questions should be directed to:
Robert Nunes
Remedial Project Manager
Central New York Remediation Section
U.S. Environmental Protection Agency
290 Broadway. 20th Floor
New York. New York 10007-1866
Telephone: (212) 637-4254
Telefax: (212)637-3966
Internet: nunes.robert@epamail.epa.gov
------- |