Results of 2001 Barksdale Site Investigation April 2, 2002 Presented by: DuPont Corporate Remediation Group

April 2, Barksdale Site Investigation Results2 Presenters n Brad Nave – Introduction, Background, and General Project Overview n Jim Richenderfer, Ph.D. – Geology and Hydrogeology n Cary Pooler, P.G. – Groundwater Analytical Results n Jon Hammerberg, P.E. – Former Operation and Production Areas n Brad Nave – Recommendations and next steps – Contact information

April 2, Barksdale Site Investigation Results3 Site Map WW-I Production Area WW-II Production Area Burning Ground Area WW-I Acid Production Area

April 2, Barksdale Site Investigation Results4 Today’s Public Meeting n Present an overview of the scope of the 2001 site investigation n Share the investigation results and conclusions n Discuss future investigation/remediation program n Discuss potential future alternative drinking water supplies n Answer questions

April 2, Barksdale Site Investigation Results5 The DuPont Philosophy Conduct investigations that allow DuPont and the regulatory agency to make informed decisions and take appropriate steps to protect human health and the environment

April 2, Barksdale Site Investigation Results6 Overall Project Objectives n Continue to provide drinking water that meets appropriate Wisconsin regulatory standards for all site-related compounds n Develop plan for long-term drinking water supply and implement as appropriate n Evaluate for potential off-site surface issues and take appropriate action n Identify priority source areas and take appropriate action

April 2, Barksdale Site Investigation Results Investigation Major Findings n Two plumes are indicated in groundwater (east central area and northeast area) n One former operation area was identified as a potential source area of site-related constituents detected in groundwater n Further investigation is needed at three former production areas where site-related constituents were detected n One off-site area was identified for further investigation n Deeper portion of aquifer remains a potential alternative source for drinking water

April 2, Barksdale Site Investigation Results8 Site Map WW-I Production Area WW-II Production Area Burning Ground Area WW-I Acid Production Area

April 2, Barksdale Site Investigation Results9 Objectives of 2001 Investigation n Developed by DuPont and approved by WDNR n Investigation objectives: – Better understand vertical and horizontal groundwater flow, particularly near the northeastern area of the site – Better understand the distribution of site-related constituents in groundwater – Determine if residual site-related constituents are present at three former production areas and one former operation area – Begin to understand condition of groundwater in deeper sandstone

April 2, Barksdale Site Investigation Results10 Investigation Activities n Field work initiated in April 2001 and completed November 2001 n Further characterization of site hydrogeology: – Drilled 74 boreholes (7,117 feet total) and logged 31 (one well at each cluster) with state-of-the-art geophysical methods – Installed 66 new permanent and 7 temporary groundwater monitoring wells (5,605 feet total) – Sampled 89 wells

April 2, Barksdale Site Investigation Results11 Investigation Activities (continued) n Further characterization of site-related compounds in soil and groundwater: – Chemically analyzed 173 soil, sediment, surface water, and groundwater samples n Integrating and interpreting all data to refine understanding of the site (report in preparation)

Geology and Hydrogeology Jim Richenderfer, Ph.D.

Regional Geology Post-Glacial Material Clay, beach sand, topsoil and stream sediments SE > < NW 900 RECHARGE AREA Pitted Outwash NTS Horizontally msl Barrens Long Lake Picnic Area Souix River Brinks Sta. Former DuPont Site Souix River Hwy Bono Creek Stratified Outwash and Till Sandstone Glacial Material

Site Geology / Hydrogeology Hwy 13 Ondassagon Rd GW Flow Directions Upper Sandstone Lower Sandstone (reportedly up to 4000 ft deep) Glacial Materials Post-glacial Clay Monitoring Wells Shallow IntermediateDeep GW SE > < NW

Post-Glacial Clay Lower Sandstone Glacial Material Stratified till and outwash Upper Sandstone

Post-Glacial Clay Lower Sandstone Upper Sandstone Typical Geology in Eastern Portion of Site Glacial material observed in western area of site absent

Site Geology / Hydrogeology Hwy 13 Ondassagon Rd GW Flow Directions Upper Sandstone Lower Sandstone (reportedly up to 4000 ft deep) Glacial Materials Post-glacial Clay Monitoring Wells Shallow IntermediateDeep GW SE > < NW

Regional Geology Post-Glacial Material Clay, beach sand, topsoil and stream sediments SE > < NW 900 RECHARGE AREA Pitted Outwash NTS Horizontally msl Barrens Long Lake Picnic Area Souix River Brinks Sta. Former DuPont Site Souix River Hwy Bono Creek Stratified Outwash and Till Sandstone Glacial Material

April 2, Barksdale Site Investigation Results19 Site Geology and Hydrogeology (continued) Intermediate Zone Potentiometric Surface Map

April 2, Barksdale Site Investigation Results20 Key Findings Geology and Hydrogeology n Site geology is consistent with regional geology n Three flow zones present at the site: – Shallow - predominately within glacial materials – Intermediate - flow occurring in a zone extending from base of Shallow Zone to upper portion of lower sandstone – Deep Zone - occurs deeper in lower sandstone and is characterized by upward gradient, lower TDS, and different natural chemistry data

April 2, Barksdale Site Investigation Results21 Key Findings Geology and Hydrogeology (continued) n Horizontal flow in each zone is generally to the southeast, with a local eastern component in the northeast n Data collected to date indicates the deep zone may be hydraulically isolated from the shallow and intermediate zones

Groundwater Analytical Results Cary Pooler, P.G.

April 2, Barksdale Site Investigation Results23 Groundwater Analytical Results n Extensive analytical program where each sample was quantified for primary site-related constituents, volatile organic compounds (VOCs), and metals n Analytical results reviewed for quality assurance n Results were compared to regulatory screening levels to identify constituents of potential concern (COPCs) – WDNR Enforcement Standards – Wisconsin Department of Health Drinking Water Guideline values n Results incorporated into understanding of on-site and off-site groundwater conditions

April 2, Barksdale Site Investigation Results24 Groundwater Analytical Results (continued) Nitroaromatic and Nitramine Organic COPCs Non-Residential Wells - October 2001

April 2, Barksdale Site Investigation Results26 Groundwater Analytical Results (continued) Nitroaromatic and Nitramine Organic COPCs Non-Residential Wells - October 2001

Construction details were available for 10 potable wells. Additional potable well construction details to be determined.

April 2, Barksdale Site Investigation Results28 Groundwater Analytical Results (continued) Nitroaromatic and Nitramine Organic COPCs Non-Residential Wells - October 2001

April 2, Barksdale Site Investigation Results30 Groundwater Analytical Results (continued) Volatile Organic COPCs Non-Residential Wells - October 2001

April 2, Barksdale Site Investigation Results32 Groundwater Analytical Results (continued) Volatile Organic COPCs Non-Residential Wells - October 2001

April 2, Barksdale Site Investigation Results34 Groundwater Analytical Results (continued) Volatile Organic COPCs Non-Residential Wells - October 2001

April 2, Barksdale Site Investigation Results36 Groundwater Analytical Results (continued) Metals Non-residential Wells - October 2001

April 2, Barksdale Site Investigation Results37 Conclusions for Groundwater n Two plumes are indicated in groundwater (east central area and northeast area) and COPCs are concentrated in these areas n 2,4-DNT and 2,6-DNT were the most commonly detected site-related compounds and are limited to the shallow and intermediate flow zones n VOC COPCs are limited to a few wells n Metals concentrations in groundwater are not indicative of site-related activity n Iron and manganese recognized as regionally elevated

April 2, Barksdale Site Investigation Results38 Conclusions for Groundwater (continued) n Deep aquifer: – Nitramines and nitroaromatics were not detected – Data collected generally supports conclusion that the deep zone may be hydraulically isolated from the shallow and intermediate zones

Former Production and Operation Areas Jon Hammerberg, P.E.

April 2, Barksdale Site Investigation Results40 Site Map Cary E. Pooler: Insert new site basemap. Map should include surrounding roads, residences/res wells (No ID for the res wells), contain all monitoring wells (with single cluster ID, I.e., PZ-01), and depict WW-I Area, WW-I Acid Production Area, WW-II Area, Burning Ground, ad Off-site Pond. Cary E. Pooler: Insert new site basemap. Map should include surrounding roads, residences/res wells (No ID for the res wells), contain all monitoring wells (with single cluster ID, I.e., PZ-01), and depict WW-I Area, WW-I Acid Production Area, WW-II Area, Burning Ground, ad Off-site Pond. WW-I Production Area WW-II Production Area Burning Ground Area WW-I Acid Production Area

April 2, Barksdale Site Investigation Results41 Objectives at Former Production Areas Objectives n Evaluate areas identified visually that: – May be a potential source to groundwater – May be susceptible to erosion and potentially off-site migration

April 2, Barksdale Site Investigation Results42 Former Production Areas (continued) 2001 Scope of Sampling Work

April 2, Barksdale Site Investigation Results43 Former Production Areas (continued) WW-I Area Pond 2

April 2, Barksdale Site Investigation Results44 Former Production Areas (continued) WW-I Area

April 2, Barksdale Site Investigation Results45 Former Production Areas (continued) WW-II Area

April 2, Barksdale Site Investigation Results46 Former Production Areas (continued) WW-I Acid Production Area

April 2, Barksdale Site Investigation Results47 Former Production Areas (continued) WW-I Acid Production Area

April 2, Barksdale Site Investigation Results48 Former Production Areas (continued) n Analyses included primary site-related constituents, VOCs, SVOCS, and metals n COPC(s) in these areas were defined by media type: – Soil and Sediment: n Concentrations of detected constituents that exceed direct contact Residual Contaminant Levels (RCLs) derived from EPA guidance (per WDNR) for non-industrial use, and – Surface water: n Any detected site-related constituents

April 2, Barksdale Site Investigation Results49 Former Production Areas (continued) Former Production Areas - COPC Summary

April 2, Barksdale Site Investigation Results50 n Conclusions: – Site-related constituents have been detected at the WW-I, WW-II, and WWI-APA Areas – Erosion control measures will be implemented as appropriate to prevent potential off-site migration of site-related constituents Former Production Areas (continued)

April 2, Barksdale Site Investigation Results51 Former Operation Area n Former Burning Ground – Former operations area that retired site staff report as the location where off-specification nitroglycerin and TNT and other wastes were burned – Composition and physical nature of wastes evaluated using samples collected from test trenches – Seven temporary wells installed to evaluate if wastes within the Burning Ground are releasing to groundwater – Some sediment samples not yet collected

April 2, Barksdale Site Investigation Results52 Remote controlled backhoe digging trenches at Former Burning Ground. Former Operation Area (continued)

April 2, Barksdale Site Investigation Results53 Highway 13 Former Burning Ground Highway 13

April 2, Barksdale Site Investigation Results54 Former Operation Area (continued) n Findings at the Former Burning Ground : – Waste present consists of soil, ash, charred wood, metal, broken glass, and ceramics – Waste averages about 7-ft in depth and is located within an approximate area of 33,000 sq. ft. – Waste is near both the groundwater table and the channel of an intermittent surface drainage. The drainage was dry during the investigation

April 2, Barksdale Site Investigation Results55 Former Operation Area (continued) n Findings at the Former Burning Ground (continued): – DNTs, nitrobenzenes and one PAH were present at concentrations greater than RCLs – All other detections were very near laboratory detection limits – The detections directly below the waste were elevated, but the concentrations southeast of the Burning Ground were an order of magnitude lower

April 2, Barksdale Site Investigation Results56 Former Operation Area (continued) n Conclusions for the Former Burning Ground: – A release to groundwater is indicated which may have contributed to the east central area of groundwater impact at the site – Further investigation is warranted to evaluate any potential exposure pathways

April 2, Barksdale Site Investigation Results57 Additional Sampling n Beyond scope specified in original work plan n Conducted east of Highway 13 in a pond down- gradient of the Burning Ground n Two sediment samples were collected and analyzed for primary site-related constituents, VOCs, SVOCS, and metals n Findings and Conclusions: – Results indicate the presence of primary site-related constituents, VOCs, and a metal, but these concentrations are less than non-industrial RCLs for direct contact – Further investigation is warranted

April 2, Barksdale Site Investigation Results58 Additional Sampling NEW SAMPLES Burning Ground HWY 13

Summary of Major Findings and Conclusions, and Recommendations Brad Nave

April 2, Barksdale Site Investigation Results60 Summary of 2001 Investigation Findings and Conclusions n Groundwater: – Two plumes are indicated in groundwater (east central area and northeast area) – Nitroaromatic and nitramine organic compounds are the primary COPCs for groundwater and are limited to the shallow and intermediate zones – Deep flow zone data indicate this interval has potential as an alternative drinking water supply

April 2, Barksdale Site Investigation Results61 Summary of Major Findings and Conclusions (continued) n Former Production Areas: – Results from each of the former production areas indicate the presence of site-related constituents n Former Operation Area: – A release to groundwater is indicated which may have contributed to the east central area of groundwater impact at the site n Site-related constituents detected in an off- site pond down-stream of the Burning Ground

April 2, Barksdale Site Investigation Results62 Review of Overall Project Objectives n Continue to provide drinking water that meets appropriate Wisconsin regulatory standards for all site-related compounds n Develop plan for long-term drinking water supply and implement as appropriate n Identify any potential off-site surface issues and take appropriate action n Identify priority source areas and take appropriate action

April 2, Barksdale Site Investigation Results63 Recommendations n Planning for long-term drinking water supply: – Confirm no site-related impacts in deep zone and general chemical quality based on further sampling data – Better understand DNT distribution in groundwater: n Obtain residential construction details (via direct measurement) n Install additional monitoring wells

April 2, Barksdale Site Investigation Results64 Recommendations (continued) n Planning for long-term drinking water supply (continued): – Further evaluate intermediate and deep zone interaction: n Conduct deep zone pumping tests n Confirming analytical results

April 2, Barksdale Site Investigation Results65 Recommendations (continued) n Addressing off-site issues: – Continue investigation at pond southeast of Burning Ground – Identify other potential off-site areas of concern (historical research) and investigate, if appropriate – Implement interim erosion control measures as appropriate to prevent potential off-site migration of site-related constituents – Complete sediment sampling near Burning Ground

April 2, Barksdale Site Investigation Results66 Recommendations (continued) n Identifying and addressing priority source areas: – Continue detailed historical research to further understand past operations – Work with WDNR to develop a basis of future investigation activity

Questions and Comments?

April 2, Barksdale Site Investigation Results68 General Information n DuPont contact information: – Blakeman Plumbing - New plumbing contractor n n (after hours) – Project information via website at n Next meeting will be June 2002