1. Filtration at the Bloomington, IL Water Treatment Plant

2. Old Plant Filters 1929, 1956, 1966

3. Old Plant Filters Filters #1-12: GAC-Capped Sand 435 square feet per filter (20’ x 21.75’) Operated at a flow rate of ~ 1 gpm/ft 2 Fixed surface wash nozzles

4. Old Plant Filters: Influent Trough

5. Old Plant Filters After Pressure Washing PVC Surface Wash Piping

6. Old Plant Filters: Fixed Surface Wash Nozzles PVC Pipe and Nozzles

7. Old Plant Filters: Media Removed Manifold Laterals

8. Old Plant Filters: Underdrain Perforated Cast Iron Lateral Piping : Uniform Distribution of Backwash Water

9. New Plant Filters - 1994

10. New Plant Filters: GAC Cap 24” filter cap replaced with virgin GAC every two years

11. New Plant Filters: Influent Trough Wash Water Trough Influent Channel and Wash Water Gullet

12. New Plant Filters: Influent Trough Filters #13-18 Dual-cell filters 462 square feet per filter (10.75’ x 21.5’ x 2 cells) Operated at a flow rate of ~ 2 gpm/ft 2 Rotating surface wash

13. New Plant Filters: Rotating Surface Wash Surface Wash Header

14. New Plant Filters GAC Removed Sand Layer Exposed

15. Granular Activated Carbon and Silica Sand

16. Backwash

17. Sand Grab Sample

18. Filter Core Sample Silica Sand Granular Activated Carbon

19. Top / Bottom of Sand Layer topbottom

20. New / Old Sand New sand is finer; more uniform

21. New / Old Sand D 10 (new) = 0.52 mm D 10 (old) = 0.58 mm

22. Examination of Old Sand Stereo Microscope

23. Examination of Old Sand

27. Elution of Old Sand

28. Organisms Rinsed from Old Sand

29. GAC Grab Sample

30. Chain of Custody

31. New / Old Carbon newold blackgrey

32. New / Old Carbon Old GAC has lost both ‘fines’ & larger particles

33. Examination of Old Carbon

36. Examination of Old Carbon Stalked, Epiphytic Bacteria extend from GAC surface

37. Examination of Old Carbon Bacteria fluoresce under UV illumination

38. Examination of Old Carbon Microbial Colonization of GAC Surface

39. Examination of Old Carbon

42. Replacing Lost Sand

43. The Changing of the Carbon

44. Disinfection after GAC/Sand Replacement