From 1942 to 1957, under contracts with the Manhattan Engineer District (MED) and the Atomic Energy Commission (AEC), the site was used for processing various forms of uranium compounds, for machining and for recovery of uranium metal. In 1946, the manufacture of uranium dioxide from pitchblende (the essential ore of uranium) began at a newly constructed plant. The pitchblende was acquired from the African Metals Company. Because this company retained ownership of the radium content of the ore, it was required that radium-226 and its daughter products be extracted along with the lead content. The radium and lead were precipitated, and the precipitate was sent to the Lake Ontario Ordnance Works in Lewiston, New York, and to the Feed Material Production Center in Fernald, Ohio, for storage.

Decontamination was performed at two plants from 1948 through 1950. NOTE: After Manhattan Engineer District/Atomic Energy Commission (MED/AEC) activities ceased, uranium-processing sites were decontaminated according to the standards of the day. However, today's standards are much more stringent, requiring additional cleanup. During current sampling activities, for example, the FUSRAP team tests for FUSRAP contaminants of concern (COCs) per the pertinent Record of Decision (ROD), but it doesn't test for other, non-FUSRAP contaminants that may be present. 

In 1951, the plants were released to Mallinckrodt for use with no radiological restrictions. From 1950 to 1951, an on-site plant was modified and subsequently used as a metallurgical pilot plant for uranium metal operation until it was closed in 1956. This plant was released to Mallinckrodt in 1962 after decontamination work was conducted.

Mallinckrodt currently owns the buildings formerly used under the AEC contract. At the time of the MED/AEC operations, the plants were owned by Mallinckrodt and/or leased by AEC. Certain buildings in those plants were also constructed for and owned by AEC. From 1942 through 1945, uranium processing was conducted at Plants 1, 2 and 4. In 1945, operations at Plant 2 were terminated. Some uranium metallurgical research continued at Plant 4 through 1956. From 1945 to 1957, uranium concentrate or ore was processed in buildings at Destrehan Street (Plants 6, 6E and 7). All uranium-extraction operations at the Destrehan Street location ceased in 1957.

When the St. Louis MED/AEC operations were terminated, buildings owned by the government were either demolished or transferred to Mallinckrodt as part of the decommission. Several plants within the Mallinckrodt facility, containing about 60 buildings, were involved; fewer than 20 of these buildings remain. A number of new buildings have been constructed on the property; since 1962, they have been used for the commercial production of chemicals.

Until 1997, the U.S. Department of Energy (DOE) led the cleanup of SLDS as part of its responsibility for the cleanup of FUSRAP sites. In October 1997, through the Energy and Water Development Appropriations Act, Congress transferred FUSRAP from DOE to the U.S. Army Corps of Engineers (USACE). Since that transition was effected, SLDS has fallen under the responsibility of USACE, St. Louis District.

1988 to 1998

Radiological characterization, which consisted of sampling and analyses to determine the nature and extent of contamination, was performed at SLDS in 1988 and 1989. Radiological characterization activities were conducted during 1990 on six properties adjacent to Mallinckrodt to determine whether contamination extended beyond Mallinckrodt property boundaries.

The scope of interim removal actions at SLDS was outlined in an Engineering Evaluation/Cost Analysis (EE/CA) prepared by DOE in 1991. The EE/CA was reviewed by the public, and DOE prepared a responsiveness summary to address the comments received. Subsequently, limited removal-action activities were undertaken at SLDS.

The purpose of these removal actions was to minimize human exposure to contaminated material and allow for consolidation of the impacted materials at temporary on-site storage areas.

Five interim actions were performed between 1995 and 1998:

1. In 1995, 15,043 cubic yards of contaminated soil were excavated from the Mallinckrodt Plant 10 (formerly Plant 4) area and shipped off-site for disposal at the Envirocare facility in Utah, which is now known as EnergySolutions.

2. In 1996, 750 cubic yards of contaminated soil were excavated from the City Property, Riverfront Trail area, and shipped off-site for disposal at the Envirocare facility in Utah.

3. In 1996, the 50-series buildings from Plant 2 on the Mallinckrodt property were decontaminated and demolished. Contaminated materials were transported by covered gondola cars for disposal at the Envirocare facility in Utah. Brick and cinder blocks were crushed and piled on-site to await disposition.

4. In 1997, select buildings in Plants 6 and 7 were decontaminated and demolished. Again, contaminated materials were transported by covered gondola cars for disposal at the Envirocare facility in Utah. Brick and cinder blocks were crushed and piled on-site to await disposition.

5. In 1998, Building K was decontaminated by the government and demolished by Mallinckrodt. Contaminated materials were transported by covered gondola cars for disposal at the Envirocare facility in Utah.

1998 to present

Since assuming responsibility for FUSRAP in 1997, USACE, St. Louis District, has based its approach to cleaning up SLDS on data and findings contained within four key documents: the Baseline Risk Assessment, Initial Screening of Alternatives, the Remedial Investigation and the Feasibility Study.  A Proposed Plan detailing USACE's preferred alternative was issued in April 1998.  The final cleanup remedy for accessible soils was outlined in the 1998 Record of Decision (ROD).

The 1998 SLDS ROD was published by USACE in consultation with the Environmental Protection Agency (EPA) and with concurrence from the Missouri Department of Natural Resources.  It defined remedial actions for accessible soil at the Mallinckrodt property and VPs.  The selected remedy for accessible soil was Alternative 6, Selective Excavation and Disposal.  Accessible soil is defined as soil that is not beneath buildings or other permanent structures.  Long-term monitoring was required for groundwater beneath the site as well as soils that are inaccessible as outlined in the 1998 SLDS ROD.

In March 2005, the Memorandum for Record: Non-Significant Change to the Record of Decision for SLDS was published, which provided specific clarifications regarding the delineation of the SLDS boundary.  Additional VPs were determined to be impacted by MED/AEC wastes from SLDS.  In addition, certain property boundaries and, in some cases, the associated property owners differed from those originally identified in the 1998 SLDS ROD.  The following specific areas were addressed:

 · Designating VPs by assigning property-specific alphanumeric identification numbers;

 · Modifying some VP boundaries due to changes in property boundaries after issuance of the 1998 SLDS ROD;

 · Clarifying that contaminated soil under active rail lines on the three railroad properties is inaccessible;

 · Amending the SLDS boundaries to increase the geographical area/scope of SLDS to include additional areas to the north, south and west of the site; and

 · Adding the Terminal Railroad Soil Spoils Area, located south of SLDS, to amended geographical area of SLDS.

Before any actions are performed on a VP, a Pre-Design Investigation (PDI) is performed. The PDI summarizes the existing/historical data, defines additional analytical data needs and determines if residual radiological contamination above the 1998 SLDS ROD remediation goals (RGs) are present on the property. Once the property has been sampled and completely characterized, a Pre-Design Investigation Report (PDIR) is prepared that documents the results of the PDI activities that were performed at the property.

If the data presented in the PDIR meets the 1998 SLDS ROD RGs, a Final Status Survey Evaluation (FSSE) is then performed.

An FSSE provides detailed information regarding:

 1. The survey process for soil and structures (including the design, methodology and approach for area-weighted averaging);

 2. The assessment of survey results for soil and structures (including statistical tests and data quality);

 3. An assessment of residual risk and dose; and

 4. Conclusions.

An FSSE is conducted (at the St. Louis FUSRAP Sites) to ensure that any residual radioactivity complies with the criteria specified in the 1998 SLDS ROD for protecting human health and the environment.

If a property meets the 1998 SLDS ROD RGs during the PDI process, the property can be released.  As a result, USACE prepares a PDIR/FSSE for that property.  

Several properties have been released under the PDIR/FSSE process:

 · 2002:  DT-1 formerly Archer Daniels and Midland and PVO Foods

 · 2006:  Mallinckrodt, Inc. Plants 3, 8, 9 and 11;  DT-20 Richey;  DT-21 Favre;  DT-22 Tobin Electric;  DT-23 InterChem;  DT-24 Bremen Bank;  DT-25 Eirten’s Parlors (OT Hodges);  DT-26 UAA Local 1887;  DT-27 Dillon;  DT-28 Challenge Enterprise;  DT-30 ZamZow Manufacturing;  DT- 32 Westerheide Tobacco Store

 · 2009:  DT-35 Factory Tire Outlet;  DT-36 OJM Inc.

 · 2010:  DT-5 Ameren UE,  DT-13 Cash’s Scrap Metal,  DT-14 Cotto-Waxo Company,  DT-16 Star Bedding Company,  DT- 18 Curly Collins Recycling

 · 2012:  DT-15 City Properties (MSD Lift Station),  DT-34 Hjersted

 · 2013:  DT-37 Lange Stegmann.

When the PDI process determines that a property doesn't meet the 1998 SLDS ROD RGs, it must be remediated. A Remedial Design/Remedial Action Work Plan (RD/RAWP) is prepared, and the property is then remediated. The remediation is completed when the property meets the FSSE.

A Post-Remedial Action Report (PRAR) is prepared when remedial activities are completed on a property. The PRAR documents the history, the site conditions and the response actions that occurred on a property. PRARs will be used collectively to provide supporting documentation for development of the Final Close-Out Report.

After Remedial Activities (RA) are completed and the property meets the 1998 SLDS ROD RGs, properties are released under a PRAR/FSSE.

USACE has conducted RA in accordance with the 1998 SLDS ROD to address MED/AEC contamination.  FSSEs for the accessible areas (in accordance with the 1998 ROD) have also been completed following RA for the following properties:

 · Mallinckrodt Plant 1

 · Mallinckrodt Plant 2

 · Mallinckrodt Plant 9

 · TRRA Soils Spoils Area

 · DT-3 Norfolk Southern Railroad

 · DT-4 Gunther Salt

 · DT-6 Heintz Steel and Manufacturing

 · DT-7 Midwest Waste

 · DT-8 PSC Metals

 · DT-10 Thomas and Proetz Lumber Company

 · DT-11 City of Venice Property (formerly McKinley Bridge)

 · DT-17 Christiana Court, LLC

 · DT-29 Midtown Garage.

Current RA at SLDS includes the following remediation:

 · Destrehan Street - East/Plant 7 West-North - Remedial activities (RA) of this area began in June 2016. Approximately 70 percent of the projected contaminated-soil volume of 16,000 bank cubic yards has been removed. RA of this area is currently scheduled for completion in 2018.

 

 · Mallinckrodt Inc. Plant 1 Former Building 17 Area - Preparation of this area, including Pre-Design Investigation sampling, began in August 2016. Approximately 40 percent of the projected 3,100 bank cubic yards has been excavated. RA of the building footprint area is scheduled for completion in 2018.

 

In September 2012, the Remedial Investigation and Baseline Risk Assessment Report (RI/BRA) for the Inaccessible Soil Operable Unit (ISOU) at the St. Louis Downtown Site was published. This document defines the nature and extent of MED/AEC soil contamination present in the ISOU at SLDS. The document also assesses the associated risk to human health and the environment under the current and anticipated future land use for SLDS.

On Jan. 3, 2014, USACE issued a Proposed Plan for the Inaccessible Soil Operable Unit Group 1 Properties at SLDS.

USACE conducted a public hearing Jan. 30, 2014, to present and accept comments on this Proposed Plan. Public comments were accepted and incorporated into the Record of Decision (ROD) in the Responsiveness Summary. The ROD was published Sept. 29, 2014. A copy can be found in the Document section below.

Record of Decision for the Inaccessible Soil Operable Unit Associated with Group 1 Properties at SLDS - Rev 0 9-29-2014

Community Involvement Plan

Environmental Monitoring Implementation Plan for the St. Louis Downtown Site for Calendar Year 2023

Environmental Monitoring Implementation Plan for the St. Louis Downtown Site for Calendar Year 2022

Environmental Monitoring Implementation Plan for the St. Louis Downtown Site for Calendar Year 2021

Environmental Monitoring Implementation Plan for the St. Louis Downtown Site for Calendar Year 2020

Environmental Monitoring Implementation Plan for the St. Louis Downtown Site for Calendar Year 2019

• St. Louis Downtown Site Annual Environmental Monitoring Data and Analysis Report (EMDAR) for Calendar Year 2022
• St. Louis Downtown Site Annual Environmental Monitoring Data and Analysis Report (EMDAR) for Calendar Year 2021
• St. Louis Downtown Site Annual Environmental Monitoring Data and Analysis Report (EMDAR) for Calendar Year 2020
• St. Louis Downtown Site Annual Environmental Monitoring Data and Analysis Report (EMDAR) for Calendar Year 2019
• St. Louis Downtown Site Annual Environmental Monitoring Data and Analysis Report (EMDAR) for Calendar Year 2018
• St. Louis Downtown Site Annual Environmental Monitoring Data and Analysis Report (EMDAR) for Calendar Year 2017
• St. Louis Downtown Site Annual Environmental Monitoring Data and Analysis Report for Calendar Year 2016
• St. Louis Downtown Site Annual Environmental Monitoring Data and Analysis Report for Calendar Year 2015
• St. Louis Downtown Site Annual Environmental Monitoring Data and Analysis Report for Calendar Year 2014

SLDS EMDAR CY13 Rev 0 7-23-2014

SLDS EMDAR Rev 07-19-2013

SLDS EMDAR Rev 07-13-2012

SLDS EMDAR Rev 07-08-2011 - main text (172 pages)

SLDS Record of Decision - main text (90 pages)

SLDS Record of Decision - Appendix A, Detailed Responses to Comments (115 pages)

SLDS Proposed Plan (16 pages)

SLDS Feasibility Study (258 pages)

SLDS ISOU Proposed Plan for Group 1 Properties

SLDS ISOU-RI Final 09-20-2012 Part 1

SLDS ISOU-RI Final 09-20-2012 Part 2

SLDS ISOU-RI Final 09-20-2012 Part 3

SLDS ISOU-RI Final 09-20-2012 Part 4

SLDS ISOU-RI Final 09-20-2012 Part 5

SLDS ISOU-RI Final 09-20-2012 Part 6