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Onondaga Lake Bottom Site Fact Sheet - July 2005

The New York State Department of Environmental Conservation (NYSDEC) and the United States Environmental Protection Agency (EPA), in cooperation with the New York State Department of Health, have issued the Record of Decision (ROD) for the Onondaga Lake Bottom site, a subsite to the Onondaga Lake National Priorities List Site. The ROD, which documents the selected remedy for the site, was signed on July 1, 2005. The ROD includes a Responsiveness Summary which responds to the comments received during the public review process.

This fact sheet highlights the Record of Decision and provides site background information, as well as contact information should you desire additional information.


At its chemical production plants near Onondaga Lake, Allied-Signal, Inc., now Honeywell, used or produced hazardous and non-hazardous substances since 1917. In June of 1989, the State filed a legal action in US District Court against Allied, seeking environmental remediation and natural resource damages arising from the company's pollution of the Onondaga Lake system. The lake and related contaminated areas were listed on the EPA's Superfund National Priorities List (NPL) in December 1994 and is included on the State Superfund list.

A Remedial Investigation (RI) which was completed in 2002 investigated the nature and extent of contamination in Onondaga Lake. It included the collection and analysis of over 6,000 samples (e.g., sediment, water, groundwater, and biota). Some of the RI's findings are as follows: Mercury contamination is found throughout the lake, with the most elevated concentrations detected in sediments in the Ninemile Creek delta and in the sediments and wastes present in the southwestern portion of the lake. Other contaminants present within Onondaga Lake sediments include benzene, toluene, ethylbenzene, and xylenes (BTEX), chlorinated benzenes, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and polychlorinated dioxins and furans. These contaminants are primarily found in the southwestern portion of Onondaga Lake. Much of the contamination in this part of the lake is present in an 84 acre area known as the In-Lake Waste Deposit (ILWD). Elevated concentrations of some contaminants in certain locations of the ILWD extend to a depth of at least 25 feet in lake sediments. Onondaga Lake fish have elevated contaminant levels and contamination in the lake presents risks to all trophic levels of the Onondaga Lake ecosystem.

In addition to determining the nature and extent of contamination, the RI also included an evaluation of the fate and transport of contaminants, and the completion of a human health risk assessment and a baseline ecological risk assessment.

Elements of the Remedy

Key elements of the Record of Decision include:

  1. Dredging of as much as an estimated 2,653,000 cubic yards of contaminated sediment/waste from the lake.
  2. Placement of an isolation cap over an estimated 425 acres of the shallower portion (where water depths are less than 30 feet)of the lake bottom.
  3. Placement of a thin-layer cap over an estimated 154 acres of the deeper portion (where water depths are greater than 30 feet) of the lake bottom.
  4. Construction/operation of a hydraulic control system along the SMU 7 shoreline to maintain cap effectiveness.
  5. Treatment and/or off-site disposal of the most highly - contaminated materials (e.g., pure phase chemicals segregated during the dredging/handling process). The balance of the dredged materials will be placed in one or more Sediment Consolidation Areas (SCAs), which will be constructed on one or more of Honeywell's Solvay wastebeds that historically received process wastes from Honeywell's former operations.
  6. Treatment of water generated by the dredging and sediment handling processes to meet NYSDEC discharge limits.
  7. An oxygenation pilot study in the deeper portion of the lake to reduce mercury methylation and dissolved mercury concentrations. This study will be followed by full-scale oxygenation if supported by the pilot study.
  8. The monitoring of the natural covering of the contaminated sediments with clean sediments (Monitored Natural Recovery) discharged from tributaries to the lake.
  9. Completion of a comprehensive lakewide habitat restoration plan.
  10. Habitat reestablishment in areas where dredging/capping will occur.
  11. Habitat enhancement along an estimated 1.5 miles of shoreline and over approximately 23 acres to stabilize deposits and promote submerged macrophyte growth.
  12. Implementation of institutional controls including the notification of appropriate government agencies with authority for permitting potential future activities which could impact the implementation and effectiveness of the remedy.
  13. Implementation of a long-term operation, maintenance, and monitoring (OM&M) program to monitor and maintain the effectiveness of the remedy.
  14. The control of contamination migrating to the lake from the various upland sites is an integral part of the overall cleanup of Onondaga Lake. The timing of remedial activities in Onondaga Lake will need to be coordinated with the remedial work which will be performed as part of the remedies at the upland sites.
  15. Collection of additional data needed for design of the remedy.

The cost to implement this remedy is estimated at $451 million with a three-year design and a four-year construction period.

Public Comments

The public comment periods on the State's Proposed Plan to address hazardous waste concerns in Onondaga Lake occurred from November 29, 2004 until March 1, 2005 and from April 1, 2005 until April 30, 2005. Nearly 250 people attended two public meetings and approximately 250 people attended three informational sessions. Over 100 people spoke at the meetings and/or submitted written comments. The informational sessions provided an opportunity for the public to learn more about the site and the Proposed Plan from NYSDEC staff. At the public meetings, the NYSDEC presented the proposed cleanup activities as contained in the Proposed Plan, responded to questions from the public, and accepted public comments.

Many commentors requested that the cleanup proceed without delay. Several asked for better access to information. Several expressed concerns regarding safety and potential impacts from the sediment consolidation area. Technically knowledgeable organizations and groups commented on the Proposed Plan with respect to mercury cycling, modeling, oxygenation and removal and disposal of sediments. There were many comments received regarding sampling and monitoring both during the design and during the long-term monitoring which will be used to evaluate remedy effectiveness. Some commentors opposed the Proposed Plan, stating the preferred remedy was either too aggressive or that is was not sufficiently extensive. Comments and questions are specifically addressed in the Responsiveness Summary portion of the ROD.

Next Steps

NYSDEC will continue to work with Honeywell toward implementation of this remedy. Technical documents will need to be reviewed and approved throughout the design and construction phases of the project to help ensure the effectiveness of the remedy. Additionally, it will remain a NYSDEC priority to continue the public outreach process. Meetings with interested parties, the public and the scientific community are expected to continue with the purpose of fostering good communication, progress, and a project that benefits the entire community. Updates will also be provided through fact sheets such as this one.