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Missouri Water Science Center

Summary of Feasibility Study results for the Front Street Site (OU1):

After a site is listed on the National Priorities List (commonly referred to as Superfund), the EPA performs a remedial investigation (RI) to gather data needed to determine the nature and extent of contamination at a site and support technical and cost analyses of remedial alternatives. After the RI has commenced, EPA conducts the feasibility study (FS), which considers different technologies for cleaning up the site and presents several possible alternatives. The FS uses data collected in the RI to generate and evaluate various remedial alternatives for the site. Together, these studies usually are referred to as the RI/FS. Sometimes these documents are combined under one cover called the remedial investigation-feasibility study of the site, but more often they are separate documents. In the case of OU1 and OU3 at the Riverfront Site, the RI and the FS are separate documents.

Results of the Human-Health Risk Assessment indicated that contaminants at OU1 pose carcinogenic and non-carcinogenic human-health risks. The FS presents remedial alternatives to address the contamination and mitigate these risks. The FS for the Front Street Site (OU1) was done by Black & Veatch Special Projects Corporation. While preparing the FS, Black & Veatch evaluated or "screened" a large number of possible remedial technologies that could address the contamination at OU1. Many of the possible remedial technologies were eventually excluded because they were not suitable to the site conditions, were not effective for the contaminants present at OU1, or were not cost effective. Because OU1 has soil and ground water contamination, individual technologies were combined to address both types of contamination. After carefully reviewing the technologies, Black & Veatch developed eight possible solutions for the contamination at OU1. These solutions are referred to as remedial alternatives. The remedial alternatives combine technologies to address both soil and groundwater contamination at OU1.

The goals in developing the preliminary remedial alternatives are to provide both a range of cleanup options and sufficient detail to adequately compare the alternatives. These alternatives were compared against seven criteria required under federal law. The criteria are: protection of human health and the environment; compliance with applicable, relevant, and appropriate requirements (State and Federal laws); long-term effectiveness and permanence; reduction of contaminant toxicity, mobility, or volume through treatment; short-term effectiveness; implementability; and costs.

The remedial alternatives range from “no action” (required to be considered by federal law), through limited action with "institutional controls", to containment of the contaminants, to very invasive and costly excavation or in-situ full-scale treatment of the contaminants. The "no action" alternative serves as a baseline against which other technologies can be compared. The FS document has a summary of the remedial alternatives for OU1 and the text of the document describes and evaluates each alternative in detail. The FS also compares the alternatives against each other.


The following is a listing of the remedial alternatives presented in the FS for OU1. The alternatives list shows the ground-water remedy first, a "/" then the soil remedy. Except #1, all of the alternatives involve some sort of public education and institutional controls.

  1. No action/No action. The site remains in its present condition. This alternative is a baseline alternative against which the effectiveness of the other alternatives can be compared and is required by federal regulation. Reviews of the Site are required and would be completed every 5 years.
  2. Limited action/Limited action. Institutional controls would be used to address the potential health risks associated with both the contaminated groundwater and soils. Institutional controls would consist of deed and zoning restrictions, permits, and public education.
  3. Monitoring/Limited action. Installation and periodic sampling of new and existing wells would be used to monitor changes in contaminant levels in the ground water [map showing well network]. Institutional controls and public education would be used to minimize contact with contaminated ground water and soils.
  4. Monitoring/Limited excavation and offsite disposal. Groundwater monitoring and institutional controls would be used to address the potential health risks associated with contaminated groundwater [map showing well network]. A limited amount (the upper six feet) of contaminated soil would be excavated. The contaminated soil would be taken off-site to an approved landfill [flowchart of soil process]. The excavated areas would be backfilled with clean soil.
  5. Hydraulic containment, above-ground treatment, and monitored natural attenuation/Capping and sheet piling. Pumping wells would be installed to establish a "barrier" to contaminant movement into the Missouri River [ map showing well locations]. The pumped water would be treated with activated carbon [schematic of carbon treatment process]. Sheet piles would be driven to the top of the bedrock to isolate contaminated soils from ground water, and an asphalt cap would be placed across the site to prevent surface water infiltration.
  6. Ground-water extraction, above-ground treatment/Excavation and offsite disposal. Pumping wells would be installed to quickly extract as much contaminated ground water out of the ground for treatment with activated carbon [ map showing extraction wells]. Sheet piles would be driven to the top of the bedrock, and all contaminated soil would be excavated and taken off-site to an approved landfill. The excavated areas would be backfilled with clean soil.
  7. In-situ Bioremediation/Excavation and on-site treatment. Compounds that promote natural degradation of the contaminants in the groundwater would be put into the ground through a large network of temporary "direct push" wells. Sheet piles would be driven to the top of the bedrock, and all contaminated soil would be excavated and treated on-site [schematic of soil process]. Treated soils would then be used as clean fill for the excavation.
  8. In-situ physical treatment/In situ treatment. A series of Advanced Remedial Technology (ART) wells [schematic of ART well] and soil vapor extraction (SVE) wells [ schematic of SVE well] would be installed across the Site to pull contaminants out of the ground water and the soil [map showing possible well locations]. ART wells use soil vapor extraction and air sparging technologies to remove contaminants.

Reference:

Black & Veatch Special Projects Corporation, 2003, Feasibility Study Report, Riverfront Superfund Site, New Haven Missouri: U.S. Environmental Protection Agency Region VII, contract 68-W5-004, Kansas City, Kansas.

Summaries and excerpts of studies related to Operable Unit OU1 are available for downloading.


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