US Army Corps of Engineers

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Saginaw Bay Sediment Separation

Pam Horner

USACE-Detroit

Richard A Price

ERDC-Vicksburg

Duluth, MN : 18-19 Nov 2014

SAGINAW RIVER, MI Project Location

SAGINAW RIVER, MI Project Description

formed by union of the Tittabawassee and Shiawassee Rivers 22 miles long flows northerly into the extreme inner end of Saginaw Bay, Lake Huron an entrance channel in the bay from the 27-foot contour in Saginaw Bay to

the river mouth (approximately 10 miles long); varying channel depths in the river ranging from 26 feet at the downstream

entrance, to 22 feet deep and 16.5 feet deep to the upstream limit at Green Point (not maintained) due to shallow depth)

five turning basins (one 25 feet deep at Essexville, one 22 feet deep on the east of the channel about one mile upstream from Cass Avenue in Bay City, one 20 feet deep at Carrollton, one 20 feet deep on the east side of the channel just upstream from the Sixth Street Bridge in Saginaw, and one 15 feet deep between the Bristol Street and New York Central Railway Bridges in Saginaw.

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BACKGROUND Project History

Original contaminant of concern – PCBs Levels ranged from non-detectable up to 25 ppm Contructed CDFs under 91-611 to contain

contaminated material PCB levels in river material declined over the years to

non-detectable New contaminant of concern - dioxins

0

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90

1 5 9 13 17 21 25 29 33 37 41 45 49 53 57

2004 %

Fin

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Samples

Series1

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1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33

2008 %

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Samples

Series1

Ave – 24 %

Grain Size

0 10 20 30 40 50 60 70 80 90

100

1 4 7 10 13 16 19 22 25 28 31 34 37

2011 %

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Samples

Series1

Saginaw River Dredged Material Characteristics 1999-2011

Ave – 40 %

Ave – 39 % 0

10 20 30 40 50 60 70 80 90

1 3 5 7 9 11 13 15 17

1999 %

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Samples

Series1 Ave – 47 %

Grain Size

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Saginaw River Dredged Material Characteristics - 2014

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

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Series1

Grain Size

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Saginaw River Dioxin Summary (TEQ ppt)

1999 2004 2008 2011 2014 Count 18 50 29 40 20

Min 2.1 0.0 1.6 4.9 3.9

Max 551.8 11,812.8 620.0 3,700.0 3,800.0

Ave 109.1 808.9 90.9 545.6 615.6

Std Dev 140.0 2,209.9 135.1 931.2 1,039.4

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Saginaw River 1999 Dioxin Data

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Saginaw River 2004 Dioxin Data

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2,000.0

4,000.0

6,000.0

8,000.0

10,000.0

12,000.0

14,000.0

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49

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Saginaw River 2008 Dioxin Data

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500.0

1,000.0

1,500.0

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2,500.0

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3,500.0

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Saginaw River 2011 Dioxin Data

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Saginaw River 2014 Dioxin Data

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0.0

2,000.0

4,000.0

6,000.0

8,000.0

10,000.0

12,000.0

14,000.0

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156

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Saginaw River All Dioxin Data

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Saginaw River – Highest Dioxin Locations

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Saginaw River – Highest Dioxin Locations

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Saginaw River – Highest Dioxin Locations

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UPPER SAGINAW RIVER DMPF

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Upper Saginaw River DMPF

281 acres Holds 3.1 million CY Clay dikes (11 feet) Site underlain with clay and sand lenses Cutoff wall down 10 feet

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Issue Sandy dredged material

placed in the Saginaw DMDF has potential beneficial uses but contains unacceptable levels of dioxins

Previous testing of material has demonstrated uncertainty in actual concentrations and distribution

Core TEQ,

Pg/g

MDEQ Soil Standards

10-1 36.4 Res Particulate Soil - 71,000

10-2 17 Res Direct Contact - 90

10-3 5567 Non-Res Particulate – 59,000

10-4 213 Non-Res Direct Contact - 990

10-5 11

10-6 9.2

10-7 2282

10-8 410

10-9 171 Average - 901

10-10 299 Standard Deviation - 1777

Samples collected by USACE, Sep 2010

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Solution – Improve Analytical Results

Need less variability Need characterization of dioxin distribution

in sediment fractions Need separation of dioxin from beneficial

sand

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Approach Sample cores over entire

exposed sediment surface

Characterize each core for particle size and presence of carbon (wood, coal, coke, etc)

Composite cores based on these characteristics

Improve analytical results by careful processing of samples

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Sampling Methods

Electric hammer drill was used to collect cores to a depth of 40 inches.

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Sample Preparation A sample of each mixed core was collected and placed in a 120ml

amber glass jar. The samples were dried in an oven at 42 deg C for 72 hrs. A 40-gram sub-sample was removed and lightly crushed in a mortar

to reduce aggregates The sample was then sieved through ASTM # 4 (4.76mm), #40

(0.42mm) and #200 (75um). The various fractions were weighed separately to determine % of

total mass. The remaining sample was ground in the mortar to ensure light

black carbon particles were thoroughly mixed and a subsample was collected from each and submitted for Total Carbon analysis.

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Sample Processing

A subsample of each core was characterized based on grain size and composition. Cores were composed mostly of fine to medium sand between 74 and 420um. Coarser and finer grained particles were either silt/clay, pebbles and varying sizes of black carbon.

Separation of lighter density carbon vs silica sand during the sieving process following grinding in a mortar. Sample was ground until all passed a 250um sieve.

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Particle Size Distribution, % (separately shown for 2 placement

operations)

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1A 1B 1C 1D 1E 2A 2B 2C 2D 2E 3A 3B 3C 3D 3E 4A 4B 4C 4D 4E 5A 5B 5C 5D 6A 6B 6C 6D

>4.76mm

<4.76mm

<0.42mm

<75um

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20.0

40.0

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100.0

7A 7B 8A 8B 9A 9B 10A 10B 11A 11B 12A 12B 12C 13A 13B 13C 14A 14B 14C

>4.76mm

<4.76mm

<0.42mm

<75um

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Total carbon, %

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0.5

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1.5

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2.5

3

1A 1B 1C 1D 1E 2A 2B 2C 2D 2E 3A 3B 3C 3D 3E 4A 4B 4C 4D 4E 5A 5B 5C 5D 6A 6B 6C 6D

1st year deposit

Total C, %

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0.5

1

1.5

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2.5

7A 7B 8A 8B 9A 9B 10A 10B 11A 11B 12A 12B 12C 13A 13B 13C 14A 14B 14C

2nd year deposit

Total C, %

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Dioxin Analysis Cores were composited into three distinct particle size/TOC based

samples. These are described as: ► Sand – mostly fine to coarse sands with some larger fragments

of shell, rock and coal/coke ► Fine – mostly fine to moderate sands with silt, clay and fine

organics ► Carbon – mostly sand with elevated levels of organic carbon,

primarily wood debris These composites prepared for analysis as follows:

► lightly crushed to pass a 2mm screen and analyzed as 2mm sized fraction.

► ground using a mortar and pestle to completely pass a 250um screen.

Purpose: Demonstrate the variability due to selective particle bound

contamination

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Dioxin TEQ Results

TEQ WHO2005 ND=0.5,pg/g AVG STDEV DEV/AVG

Sand 250um 505 510 514 489 555 514.60 24.50 0.05

Sand 2mm 51.8 113 106 79.4 197 109.44 54.58 0.50

Fine 250um 860 1080 906 1410 866 1024.40 233.41 0.23

Fine 2mm 564 1190 727 944 219 728.80 369.48 0.51

Carbon

250um 829 788 1140 1040 839 927.20 153.95 0.17

Carbon 2mm 1030 620 471 936 4880 1587.40 1854.62 1.17

TEQ WHO2005 ND=0.5,pg/g AVG STDEV DEV/AVG

Carbon NS NS NS 21,517.8 19,428.1 20,473.0 54.58 0.50

Fine NS NS 1,806.2 1,877.0 1,940.1 1,874.6 233.41 0.23

Sand NS NS 62.1 114.5 164.0 113.6 51.96 0.45

Sand

Washed 2.1 2.0 1.9 2.6 2.5 2.3 0.297 0.13

Core Composites

Separated Fractions

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Options and Path Forward

Washing sand can significantly reduce dioxins to acceptable levels and render suitable for recovery and beneficial use

Pilot scale project to evaluate effectiveness during dredging and/or pumping operations

Consider implications of dioxin laden residuals ►Removal for disposal ►Allow settling in pond and cap