Thursday, February 20, 2020

Computer Model Demonstration of EPA ROD Remedy


EPA’s 2008 Selected Remedy for the West Lake Landfill Site, Operable Unit 1

  1. EPA’s Public Participation and Remedy Selection Process
  2. EPA’s Description of the Remedy Selected for the Site
  3. SFS Process and Results
  4. EPA Directs the PRPs to Perform Additional Investigations and Remedial Analysis
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EPA ROD Remedy

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Demonstration of EPA ROD Remedy (.MOV file, 36.9 MB) 

1. EPA’s Public Participation and Remedy Selection Process

See Glossary of terms

  • After reviewing the results of the field investigation and a variety of potential cleanup options, EPA picked an enhanced capping and long-term monitoring remedy for OU-1.
  • EPA issued a Proposed Plan (1.3MB, PDF, opens in new window) and an Administrative Record (AR) supporting the Proposed Plan, and released these documents to the public in June of 2006. The AR file was placed at Bridgeton Trails Branch of the St. Louis County public library located near the Site. EPA published notice of the availability of the Proposed Plan in the Bridgeton/Hazelwood Suburban Journal, which was a daughter publication of the St. Louis Post Dispatch.
  • EPA scheduled a public meeting to discuss the Proposed Plan, and sent out a Fact Sheet describing the cleanup remedy and the upcoming public meeting to area residents, elected officials, and media outlets.
  • The comment period opened on June 14, 2006 and was scheduled to close 30 days later (July 14).
  • The first public meeting was held on June 22, 2006 at the Bridgeton Community Center. At the meeting, EPA provided an overview of the Site, described the preferred cleanup alternative, and explained the remedy selection process. Following the presentation, EPA listened to oral comments from the public.
  • In response to a request from the City of Bridgeton, EPA extended the comment period an additional 30 days to August 14, 2006, and then again another sixty days to October 14, 2006.
  • Following public notice, a second public meeting was held at Bridgeton City Hall on September 14, 2006. The presentation at the second meeting was narrowly focused to address public concerns with the proposed remedy which had been voiced at the first public meeting. Again, after EPA’s presentations, EPA listened to oral comments from the public.
  • In response to additional requests, EPA granted a third extension of the comment period to December 29, 2006. In total, EPA held the public comment period on the Proposed Plan open for more than six months.
  • A number of local citizens continued to be interested in EPA’s decision-making process for the Site, and so, responding to continuing community interest, EPA reopened the public comment period for the cleanup options in early 2008. EPA scheduled and held a third public meeting on March 27, 2008. EPA closed this third public comment period on April 9, 2008.
  • EPA made written transcripts of all three public meetings. EPA also accepted voluminous written comments on the Proposed Plan.
  • EPA’s responses to the comments it received at the public meetings and to the written comments are found in the Responsiveness Summary (0.2 MB, PDF, opens in new window) portion of EPA’s May, 2008 Record of Decision (ROD).

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2. EPA’s Description of the Remedy Selected for the Site

  • According to EPA, the major components of the remedy selected for the Site are as follows:

    • Install landfill cover meeting the Missouri closure and post-closure care requirements for sanitary landfills, including enhancements consistent with the standards for uranium mill tailing sites, i.e., armoring layer and radon barrier
    • Consolidation of radiologically contaminated surface soil from the Buffer Zone/Crossroad Property to the containment area
    • Apply groundwater monitoring and protection standards consistent with requirements for uranium mill tailing sites and sanitary landfills
    • Surface water runoff control
    • Gas monitoring and control including radon and decomposition gas as necessary
    • Institutional controls to prevent land and resource uses that are inconsistent with a closed sanitary landfill site containing long-lived radionuclides
    • Long-term surveillance and maintenance of the remedy
  • EPA went on to find that: “The Selected Remedy is protective of human health and the environment, complies with federal and state requirements that are applicable or relevant and appropriate, is cost effective, and utilizes permanent solutions and alternative treatment technologies to the maximum extent practicable.”

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3. SFS Process and Results

In January 2010, EPA determined that a Supplemental Feasibility Study (SFS) should be prepared for OU-1 to evaluate two additional potential remedial alternatives for the Site. Consistent with EPA’s directions, the PRPs performed an updated engineering and cost analysis of the Selected Remedy and a similar analysis of two new alternatives which would excavate all RIM in excess of a specified cleanup level from OU-1 and either send the excavated materials to a permitted, out-of-state landfill for disposal (“complete rad removal” with off-site disposal), or re-dispose of the excavated material in a new engineered landfill cell to be built within the boundaries of the West Lake Landfill Site (“complete rad removal” with on-site disposal).

Briefly stated, the findings and conclusions of the SFS are:

  • All three remedial alternatives -- the updated Selected Remedy and both “complete rad removal” alternatives -- meet EPA’s criteria for long-term protection of human health, welfare and the environment.
  • The updated Selected Remedy and the “complete rad removal” with off-site disposal alternatives appear implementable.  The “complete rad removal” with on-site disposal alternative has potential implementability issues caused by proximity to Lambert-St. Louis International Airport and regulatory and contractual restrictions on the disposal of putrescible solid waste near the Airport’s runways – these restrictions are intended to reduce or mitigate wildlife hazards to aircraft and airport facilities.
  • While all three alternatives have long-term risks within EPA’s acceptable risk range, the long-term risks (at 1,000 years) of the “complete rad removal” with off-site disposal alternative are better than the other two alternatives.
  • The short-term risks to on-site workers and to the community are worse under either of the excavation alternatives than under the updated Selected Remedy and short-term risks to workers associated with the excavation alternatives are greater than EPA’s acceptable risk range.
  • The time required to implement the updated Selected Remedy is the shortest, followed by the off-site and then the on-site “complete rad removal” disposal alternatives.
  • The cost estimate for the updated Selected Remedy is the lowest, followed by the on-site and then the off-site “complete rad removal” disposal alternatives.

A table of comparative costs, risks and schedules for the three SFS alternatives. Go to the SFS page of this site to see and download the table, the Executive Summary prepared by the PRPs, or all or portions of the full SFS Report.

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4. EPA Directs the PRPs to Perform Additional Investigations and Remedial Analysis

In May 2012, in response to questions posed by EPA’s National Remedy Review Board (NRRB), EPA directed the PRPs to perform a one-time groundwater sampling “snapshot” of all accessible groundwater monitoring wells located at either the OU-1 or OU-2 portions of the overall Site property. The PRPs sampled the wells in July-August, 2012, and issued a Groundwater Sampling Report in December 2012. The Report confirmed the findings of earlier investigations that the Site is not a source of groundwater contamination.

In June 2012 EPA indicated that it also wanted additional evaluations and analysis regarding sampling results and remedial options addressed in the SFS. EPA’s October 2012 letter confirming its directions to the PRPs concerning these additional evaluations and analysis may be viewed or downloaded here: EPA's October 2012 Letter (PDF, opens in new window). The PRPs began work on these deliverables in 2012 and that work continues in 2013.

As another part of its response to the NRRB, in November 2012 EPA itself performed downhole gamma logging of most of the groundwater monitoring wells at OU-1 and OU-2. EPA presented the results of that logging evaluation and the PRPs’ Groundwater Sampling Report in a Public Meeting held January 17, 2013 in Bridgeton, Missouri.

In January 2013, EPA informed the PRPs that it now wants a full year’s worth of periodic groundwater sampling for the Site. EPA also confirmed that it would itself perform an overland gamma scan of the surface of the Site during 2013 using an EPA-owned airplane equipped with radiological detection equipment.

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