1. US Army Corps of Engineers BUILDING STRONG ® Dredging with Turbidity Tests and the EPA in Green Bay Harbor Michael Staal, E.I.T. Civil Engineer U.S. Army Corps of Engineers Detroit District Lake Michigan Area Office –Kewaunee Sub-Office October 24, 2012

2. BUILDING STRONG ® Detroit District  Covers 82,000 square miles of land  4,000 miles of Great Lakes shoreline  Maintain 94 harbors  Primarily a civil works district, including navigation, flood control beach erosion, etc.

3. BUILDING STRONG ® Green Bay, WI N

4. BUILDING STRONG ® History of PCBs in Green Bay  In 1954, paper companies started using PCBs to make carbonless copy paper  Nearly 700,000 lbs of PCBs were released into the Fox River between 1954 and 1971  The use of PCBs was officially prohibited by federal environmental regulations in 1976 *Data from WDNR

5. BUILDING STRONG ® Green Bay PCB Concentrations *Data from WDNR

6. BUILDING STRONG ® History of PCBs in Green Bay  In 2007, a Record of Decision and a Unilateral Administrative Order required the primary responsible parties to initiate clean up of the Fox River  EPA and USACE entered into a IA to set monitoring requirements for dredging in Green Bay

7. BUILDING STRONG ® 2010 Dredging Map Area 1 Area 2 Area 3 Area 4 Mod. Area Option 2 Area Turbidity Testing Required Total Volume Dredged173,755 CY

8. BUILDING STRONG ® Turbidity Testing  Requirements ► 1 week of background testing, 8 hours a day, 1 test each 15 min. ► 2 assessments every work day, at least 4 hours apart ► Take initial test 500 feet upstream of dredge ► Then take a downstream test 250 ft -500 ft from the dredge ► Downstream test – Upstream test < 80 NTU

9. BUILDING STRONG ® 14 CY Dredging Bucket A Cable Arm Bucket with Seals and Baffles

10. BUILDING STRONG ® Steps the Contractor took to reduce Turbidity  Scows were sealed with spray foam insulation  Dredge material loaded in scows was controlled  Speed of dredging bucket was controlled.

11. BUILDING STRONG ® Turbidity Testing

12. BUILDING STRONG ® Turbidity Testing Results Maximum Difference54 NTU (after a 50 year storm) Minimum Difference0 NTU Average Difference17 NTU Average Distance from Crane399 feet The EPA has decided that turbidity monitoring no longer be used for those areas of Green Bay and Fox River Dredging as long as the Corps operates in a similar manner of dredging.

13. BUILDING STRONG ® Fox River Dock

14. BUILDING STRONG ® Bayport Disposal Facility

15. BUILDING STRONG ® Lessons Learned  Switching up testing times keeps contractor honest  Mechanical dredging can be used in a manner that does not cause large increases in turbidity  Background testing is important. Knowing how the Fox River turbidity reacts to rain events, ships, etc. helped us understand the turbidity in the river better.