Former DuPont Barksdale Works Project Update

1. Former DuPont Barksdale Works Project Update December 14, 2005 Great Lakes Visitors Center DuPont CRG

2. DuPont Company Representatives • Brad Nave: Project Director – DuPont Corporate Remediation Group • Cary Pooler: Project Manager – URS Corporation Former DuPont Barksdale Works

3. Purpose of Meeting • Reaffirm site priorities and public commitments, and provide a status update for each. • Provide an update on work completed since the August public meeting. Former DuPont Barksdale Works

4. Project Priorities and Commitments ReviewBrad Nave

5. Project Priorities Four Project Priorities: • Continue to provide drinking water that meets appropriate Wisconsin regulatory standards for all site-related compounds to residents with impacted wells. • Develop plan for long-term drinking water supply and implement as appropriate. • Evaluate for potential off-site surface water issues and take appropriate action. • Identify priority source areas and take appropriate action. Former DuPont Barksdale Works

6. Project Priorities Other Commitments: • Continue to work with WDNR in the investigation/cleanup of site impacts. • Continue to be available and communicate with neighbors. • Fulfill commitments on Home Value Protection Plan. Former DuPont Barksdale Works

7. Project Priorities continued… Priority 4: Identify priority source areas and take appropriate action. • Site investigation work has been undertaken since 1998. • Site divided into “northern” and “southern” areas. • Northern area: primary location of historical manufacturing and support operations. • Southern area: primary location of historical product storage operations. Former DuPont Barksdale Works

8. Other Commitmentscontinued… • Home Value Protection Plan • Four properties purchased to date. Two have been resold. One home removed, but property retained. • An additional offer made in late September; offer turned down and property sold in October. • Appraisals and inspections are pending for two properties. Former DuPont Barksdale Works

9. Other Commitmentscontinued… • Home Value Protection Plan (continued) • Home Value Protection Program will remain in effect until six months after alternative water is available. • Availability of the program was the last calendar day of August 2005 for most residents. Last municipal water hookup was in June 2005. Former DuPont Barksdale Works

10. Barksdale Site InvestigationCary Pooler

11. Northern Area InvestigationWork Completed to Date • Work undertaken to date in the northern area has included: • Groundwater investigation. • Historical building/process review. • Waste area identification. • Stream diversion. • Debris location/recovery. • Discrete soil sampling. • Excavation of soil adjacent to select former process and support buildings and select process ditches. Former DuPont Barksdale Works

12. Northern Area InvestigationIssues Identified • Learnings to date include: • Two separate plumes of site-related constituents in groundwater. • Over 280 historical buildings across site. • 13 waste management areas identified to date. • Two former burning grounds. • Remaining areas include empty containers, building rubble and other debris. • TNT present at surface and at depth at select building foundations and ditches. Former DuPont Barksdale Works

13. Northern Area InvestigationIssues Identified • Learnings to date (continued): • Percentage level concentrations of DNT isomers at select locations across the site. • Bare areas distributed across former manufacturing areas. • Bare areas in former acid production areas. • Potential asbestos containing material (PACM). • Debris includes empty drums, process vessels, and a variety of other metallic and non-metallic wastes. • Perchlorate preliminarily identified in groundwater. Former DuPont Barksdale Works

14. PerchlorateOverview • Perchlorate is both a naturally occurring and manmade anion consisting of chlorine bonded to four oxygen atoms (ClO4-). Former DuPont Barksdale Works

15. PerchlorateOverview • Why are we looking for perchlorate at Barksdale? • A historical document identified in February of 2005 indicated that the former Barksdale plant manager was corresponding with a chemist in Chile about staffing. • This letter may indicate a that sodium nitrate from Chile was used for as a raw material for nitric acid production at Barksdale. Former DuPont Barksdale Works

16. PerchlorateOverview • At this time, most naturally occurring sources of perchlorate appear to be geographically limited to arid environments. High natural perchlorate concentrations are found in Chilean caliche and some potash ores. • Sodium nitrate is leached from Chilean caliche to make fertilizers, among other products. • Chilean nitrate derived fertilizers were the primary fertilizers used in the United States until the 1960s. • Sodium nitrate (“soda nitre” or “Chilean saltpeter”) was formerly an important raw material for the production of nitric acid in the United States and elsewhere. Former DuPont Barksdale Works

17. PerchlorateOverview • Preliminary results: • Preliminary laboratory results indicate that concentrations in groundwater surrounding the former nitric acid production area range between 0.033 to 150 parts per billion (ppb). • Perchlorate was not detected in the two potable wells sampled on-site. Former DuPont Barksdale Works

18. PerchlorateOverview • EPA has established a 24.5 ppb limit in drinking water for perchlorate. • Perchlorate inhibits iodide uptake. • Next steps: • Sample additional wells on-site in Spring 2006. Former DuPont Barksdale Works

19. Northern Area InvestigationHistorical Buildings/Ditches Former DuPont Barksdale Works

20. Northern Area InvestigationWork Completed to Date • Trenching Investigation • Investigation of subsurface residual product distribution and identification of former subsurface pit and drain locations. • Phase I – Identify typical conditions • Used remote controlled excavator • Focus on soil adjacent to former process buildings. Former DuPont Barksdale Works

21. Northern Area InvestigationWork Completed to Date • Trenching Investigation(continued): • Phase II – • Used shielded conventional excavator. • Focus on process ditches & buildings similar to those from Phase I. • Used bulk (mechanized) excavation to determine location and expose deposits • Used forensic (hand dug) excavation to determine detail of deposition of solid deposits. Former DuPont Barksdale Works

22. Northern Area InvestigationWork Completed to Date • Phase I excavation (at Finishing Plant) Former DuPont Barksdale Works

23. Northern Area InvestigationWork Completed to Date • Phase II excavation (at Refine ditch) Former DuPont Barksdale Works

24. Northern Area InvestigationHistorical Buildings/Ditches TNT Former DuPont Barksdale Works

25. Northern Area InvestigationWork Completed to Date TNT Layer • More excavation photos showing TNT. Former DuPont Barksdale Works

26. Northern Area InvestigationWork Completed to Date • More excavation photos showing TNT. Former DuPont Barksdale Works

27. Northern Area InvestigationWork Completed to Date • More excavation photos showing TNT. Former DuPont Barksdale Works

28. TNT Removal Process • Collect & size pieces by hand • Weigh, wet, and pack in antistatic bags • Courier ship bags to St.Louis for incineration Former DuPont Barksdale Works

29. Northern Area InvestigationWork Completed to Date Former DuPont Barksdale Works

30. Northern Area InvestigationPictures of Waste Areas West Boyd Rail Fill Former DuPont Barksdale Works

31. Northern Area InvestigationPictures of Waste Areas West Boyd Rail Fill Slab Crossing Debris Former DuPont Barksdale Works

32. Northern Area InvestigationPictures of Waste Areas West Boyd Rail Fill Nitramon Area Container Dump Former DuPont Barksdale Works

33. Northern Area InvestigationPictures of Waste Areas Crushed Drum Dump Former DuPont Barksdale Works

34. Northern Area InvestigationWork Completed to Date • Typical surficial debris recovered. Former DuPont Barksdale Works

35. Northern Area InvestigationWork Completed to Date • Bare area photos. Bare Area Former DuPont Barksdale Works

36. Northern Area InvestigationPath Forward • Continue to determine distribution of site-related constituents. • Four month field effort planned for 2006. • Explore feasibility of alternative investigation techniques. • Continue TNT recovery and disposal as part investigation efforts. • Continue debris identification and recovery. • Continue to understand perchlorate distribution in groundwater. • Consider grid sampling in select areas. • Continue pilot test work at GA Tech Former DuPont Barksdale Works

37. Site-related Research Work • Continuing Georgia Institute of Technology research on destruction of DNT and TNT. • Study being conducted by Dr. Joe Hughes (Professor and Chair of the Civil Engineering Dept. at Ga. Tech) and Dr. Jim Spain. • Study initiated in early 2004 and is ongoing. • A portion of their research on TNT destruction was published in the peer reviewed journal Environmental Science and Technology this year. • Scaled-up DNT bioremediation project to address DNT contaminated soils is in progress at the Georgia Tech facility. • Soils used in the system are from the Barksdale site. • System will run until all DNT degraded or other suitable endpoint is reached • Final results should be available by the end of 2006. • Updates will be provided in future public meetings. Former DuPont Barksdale Works

38. Methanol (wood alcohol) Proposed Barksdale Soil Biodegradation Pilot • Proposed pilot project is a simple set up with low operation and maintenance requirements. Water, pH adjustment & Nutrients (phosphate, magnesium, calcium, iron) DNT Biodegradation Reactor Site Soils Contaminated w/ DNT (source of bacteria and DNT) Denitrification Reactor to Remove Nitrite (bacteria from soils) N2 + CO2 + H2O 2 NO2- 1 DNT Gravel for Drainage Methanol + NO2- Former DuPont Barksdale Works

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45. Southern Area InvestigationScope of Work • Worked with WDNR to develop a work plan to investigate southern area. • Focus of work was to: • Determine nature and extent of site-related constituents in surface soil. • Determine if current recreational use is appropriate. • Work plan approved by WDNR. • Site sampling was very comprehensive, encompassing both grid-based and biased sampling at 640 locations (416 analyzed) over 400+ acres. Former DuPont Barksdale Works

46. Southern Area Investigation Scope Former DuPont Barksdale Works

47. Southern Area InvestigationPreliminary Findings • With the exception of one occurrence of benzo(a)pyrene at the residential screening level, arsenic and lead are the only constituents that exceed residential or recreational screening levels. • The extent of contamination is generally limited to soils along historic roadways in the central portion of the parcel. (The one exception being at select samples in the northeastern corner of the parcel.) Former DuPont Barksdale Works

48. Southern Area InvestigationPreliminary Findings • The nature and distribution of contamination is consistent with our understanding of historic site operations and our experience at other munitions manufacturing sites. • Arsenic and lead concentrations are well correlated, especially in samples that exceed their respective screening criteria. Hence, selected remediation of elevated levels of one constituent would also address the other. Former DuPont Barksdale Works

49. Southern Area InvestigationPreliminary Findings • The levels of lead and arsenic observed do not represent an acute health risk, and as such, use of this area for an additional season of occasional recreational activities would not be expected to result in unacceptable exposures. • A waste disposal area (1970s berm) was identified. Waste materials primarily consist of building rubble. Former DuPont Barksdale Works

50. Southern Area InvestigationGrid Sizes Former DuPont Barksdale Works