DISTRICT OF COLUMBIA WATER AND SEWER AUTHORITY

1. DISTRICT OF COLUMBIAWATER AND SEWER AUTHORITY Biosolids Management Program Update May 22, 2008 Draft

2. Agenda • BMP Status Update • Process Alternatives • Comparison of Alternatives • Risk Management Strategy • Energy and GHG Emission Considerations • Implementation Schedule Draft

3. BMP Status Update Draft

4. Introduction • WASA has been updating the BMP to: • Determine available technologies for Blue Plains • Define projects that can be implemented within the budget, but also identify projects that provide significant O&M cost advantages • Define projects that significantly reduce continued use of lime stabilization and provide for beneficial use of final product (i.e., digester gas and biosolids) Draft

5. Introduction • WASA has determined that: • Digestion remains the cornerstone of the BMP • WASA should continue moving toward processes that result in Class A biosolids for program sustainability • Thermal Hydrolysis by Cambi is proven to be an effective biosolids treatment technology • Use of Cambi process can reduce needed digester volume by 50% • Diversity of final product is an important risk management strategy Draft

6. BMP Status • WASA conducted three expert panel workshops resulting in a recommended combined option including TH, digestion, and drying • Waste activated (hard to digest sludge) to Cambi, and Primary (easy to digest sludge) to digestion/drying • Reduces risk from processing all sludge using only one technology • Generates diverse final biosolids products • Allows WASA to gain experience with both technologies and decide which technology to proceed with in the future Draft

7. BMP Status (Cont’d) • Identified process alternatives that would maximize use of existing facilities • Identified scaled-back facilities that fit within available budget • Performed value engineering with independent team on alternatives to identify construction cost savings • Performed independent cost analyses to validate cost assumptions and factors used to prepare construction and O&M cost estimates Draft

8. BMP Status (Cont’d) • Validated feasibility and constructability concepts using independent construction and geotechnical experts • Identified risks related to construction and means to mitigate them (construction cost market continues to escalate at a rapid rate) • Estimated energy production and carbon offsets for each alternative Draft

9. BMP Status (Cont’d) • Reviewed latest population projection for Blue Plains service area and impact on solids loading and biosolids management costs • DCWASA personnel visited TH (Cambi) installations in Ireland and the United Kingdom April 29 – May 2, 2008 to: • Inspect operating and partially constructed TH plants • Discuss procurement, construction and operating issues with owners • Familiarize WASA staff with process operability and maintainability requirements • Found Cambi to be an acceptable technology for Blue Plains Draft

10. Thickening Dewatering Cambi Meso Digestion Dewatering Beneficial Use (Class A) Process Technologies Cambi Thermal Hydrolysis (TH) • TH precedes anaerobic digestion • TH uses high temp and pressure to break down sludge for faster digestion and destroys all pathogens • TH produces Class A biosolids product • TH reduces the required digester volume by half • TH can provide diversity of biosolids product with the addition of drying Draft

11. Thickening Meso Digestion Dewatering Drying Beneficial Use (Class A) Process Technologies Digestion/Drying • Provides heat dryers for digested sludge to yield Class A pellets • Reduces biosolids volume by 90% • Class A pellets can be land applied or used for fertilizer or fuel Draft

12. Thickening Dewatering Cambi Meso Digestion Dewatering Beneficial Use (Class A) Thickening Meso Digestion Dewatering Drying Beneficial Use (Class A) Process Technologies Combined (Cambi/digestion/drying) Primary Solidsand WAS • Provides heat dryers for non-Cambi digested sludge to yield Class A pellets • Provides two different types of Class A products Draft

13. Available ProjectConstruction Budget • Current Available CIP Funds = $ 308 MM • Pre-construction Cost Allowancesat 26% of Construction Cost = $ 64 MM • Available Construction Budget = $ 244 MM Draft

14. Process Alternatives – Major Equipment SPB = Sludge Processing Building Draft

15. Biosolids Loadings and Construction Cost for Alternatives Draft

16. Biosolids Loadings and Construction Cost for Alternatives Draft

17. Construction and O&M Costs of Alternatives MAD = Mesophylic Anaerobic Digesters LS = Lime Stabilization Draft

18. Construction and O&M Costs of Alternatives * The estimated cost does not account for additional costs that may be incurred when major equipment is installed in an existing building designed for other uses. Draft

19. Preliminary Comparison of Alternatives • Alternatives sized to handle all peaks and eliminate lime stabilization and cost >$370 Million (construction cost) • Cambi requests outdoor location for their process. Fitting Cambi into existing building could require modifications to their standard design which increases risk • Four digestion alternatives are within capital budget Draft

20. Preliminary Comparison of Alternatives (Cont’d) • Four digestion alternatives are above capital budget, but reduced O&M cost warrants further consideration • For each of the above, the best Cambi and combined alternatives were selected resulting in four alternatives to be compared with the base case full lime stabilization alternative Draft

21. Recommended Alternatives for Consideration Alt. 2: Cambi – 4 trains/4 digesters (w/LS for peaks and Cambi down time) Alt. 4: Cambi – 2 trains/2 digesters (w/LS) Alt. 7: Combined – 1 Cambi /5 digesters/ 2 dryers (w/LS for peaks and Cambi down time) Alt. 9: Combined – 1 Cambi/3 digesters/ 1 dryer (w/LS) Alt 12: Lime stabilization only (base case) Draft

22. Risk Management Strategy • Cambi Alternatives with Lime Stabilization (Alt. 2 & 4) • Phased implementation allows confirmation of technology and later expansion based on plant operating data and a better definition of peak loads • Use of conventional digester construction increases contractor competition • Lime stabilization manages peak solids loadings and provides backup to mitigate potential risks • Modular Cambi construction reduces initial installation costs Draft

23. Risk Management Strategy • Combined Alternatives with Lime Stabilization(Alt. 7 & 9) • Phased implementation allows confirmation of technology and later expansion of either Cambi or drying • Diversity of Class A biosolids products (Cambi cake and heat-dried biosolids) increases marketability • Use of conventional digester construction increases contractor competition Draft

24. Risk Management Strategy (Cont’d) • Lime stabilization manages peak solids loadings and provides backup to mitigate potential risks • Combined alternatives mitigate commercial risks and allow leveraging competition Draft

25. Comparative Green House Gas (GHG) Emissions Based on CO2 • Digester gas is used to generate electricity from a co-gen facility • Waste heat from power generation is used to provide energy for Cambi, drying and to heat digesters • CO2 emissions were generated from: • Net heat consumed by the process • Net electricity consumed by the process • Transportation fuel for land application of cake solids • Lime usage • Reduction of CO2 emissions are a result of: • Electricity and heat generated from the biogas • Land application of cake • Combustion of pellets in a cement kiln plant • CO2 benefits related to land application of stabilized biosolids are based on carbon sequestration and offsetting the use of chemical fertilizer Draft

26. CO2 Emission in thousand tons/yr for the selected alternatives Processes only • Red numbers in parenthesis represent negative CO2 emission or CO2 credit • The higher the numbers in ( ) the better the process in terms of GHG emission, considered as CO2 benefit. Processes and Product Use Draft

27. Electricity Productionfor Selected Alternatives Draft

28. Basis for Selection of Recommended Alternative • Costs / Available budget • Diversity of Product • Complexity of Construction • Complexity of O&M • Carbon Offsets • Energy Production • Risks Draft

29. Project Implementation Schedule Note: Some activities run concurrently Draft

30. Population Projection and Impacts • Current budget based on 2000 population projections and 330 dt/d solids production • New projections based on 2008 projections and 370 dt/d solids production Draft

31. Next Steps • Provide construction cost, schedule, May 27, 2008 and annual O&M costs to CFO • Technical Workshop June 4, 2008 • Len Benson meeting with CFO and GM ~ June 9, 2008 • EQ & Operations Committee meeting June 19, 2008 • Full Board meeting (assumed) July 3, 2008 • Draft and Final Report(Conceptual Development level) September 2008 Draft

32. THE END Draft

33. Schematics and Site Layouts of Alternatives Draft

34. Cambi and Digestion Alternatives Lime Stabilization (Existing) Draft

35. Cambi and Digestion Alternatives Draft

36. Cambi/DigestionAlternative #2 Draft

37. Cambi/DigestionAlternative #4 Draft

38. Cambi/ Digestion / Drying Lime Stabilization (Existing) Draft

39. Cambi/Digestion/DryingAlternative #7 Insert Layout for Alternative 7 Draft

40. Cambi/Digestion/DryingAlternative #9 Insert Layout for Alternative 8 Draft

41. Lime Stabilization Draft

42. Lime StabilizationAlternative 12 Insert Layout for Alternative 12 Draft