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
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.