Trial Dredging Report Port of Anchorage Harbor Deeping.pdf

U.S. Army Corps of Engineers

Alaska District

Soils and Geology Section

TRIAL DREDGING REPORT

Anchorage Harbor Deepening

Port of Anchorage, Alaska

November 2008

Trial Dredging Report Anchorage Harbor Deeping U.S. Army Corps of Engineers i Port of Anchorage, Alaska

TRIAL DREDGING REPORT

Anchorage Harbor Deepening

TABLE OF CONTENTS

TITLE PAGE Page

TABLE OF CONTENTS................................................................................................................. i LIST OF FIGURES ......................................................................................................................... i LIST OF APPENDICES.................................................................................................................. i

J.E. McAmis Trial Dredge Area 1 The Dutra Dredging Company Trial Dredge Area 2 The Dutra Dredging Company Trial Dredge Area 3

LIST OF FIGURES

Project Location and Vicinity Map ........................................................ Figure 1 Trial Dredging Area Location Map ........................................................ Figure 2

LIST OF APPENDICES

APPENDIX A – EXPLORATION LOGS

Exploration Logs AP-4590, AP-4607, and AP-4611 ...........................3 Pages

APPENDIX B – MCAMIS TRIAL DREDGE AREA SURVEYS

J.E. McAmis Trial Dredge Area Surveys............................................3 Pages

APPENDIX C – DUTRA TRIAL DREDGE AREA SURVEYS

The Dutra Dredging Company Trial Dredge Area Surveys .................4 Pages

APPENDIX D – TRIAL DREDGING PHOTOGRAPHS

Additional photographs of dredging operations.................................9 Pages

U.S. Army Corps of Engineers 1 Port of Anchorage, Alaska

TRIAL DREDGING REPORT

Anchorage Harbor Deepening

A trial dredging program was conducted in virgin areas (no previous dredging) where future dredging is planned for the Anchorage Harbor Deepening project.

Trial dredging is not a normal undertaking; however, in this case, very dense sands and gravels containing cobbles and boulders and lean clay deposits were encountered during the U.S. Army Corps of Engineers–Alaska District’s (USACE-AD) previous marine geotechnical exploration for the project. These subsurface conditions were of concern to dredging feasibility. Therefore, this trial program was developed to evaluate these problematic conditions within the virgin areas. The objectives of the program were to procure data to estimate dredging production rates, evaluate the suitability of dredging equipment, and provide a direct observation of subsurface conditions within the virgin areas where future dredging is planned. This report documents the results of the trial dredging efforts.

The basic trial dredging program consisted of dredging at three different locations to an elevation of -45 feet mean lower low water (MLLW). These areas were selected at test boring locations drilled during a previous marine geotechnical investigation. Geotechnical descriptions of the soil conditions encountered during that investigation are presented in the report titled:

“Geotechnical Findings Report, Anchorage Harbor Deepening, Port of Anchorage, Alaska” USACE-AD, June 2008.

Two contractors conducted the trial dredging: J.E. McAmis, Inc. and The Dutra Dredging Company. A project location and vicinity map along with a map showing the locations of each trial dredging area can be found as Figures 1 and 2, respectively. A summary showing the dredge area reference numbers, dredging contractors, and reference test boring exploration logs is reported in Table 1 and test boring exploration logs are provided in Appendix A. When comparing the results of these trial dredging efforts with test boring exploration logs, it should be noted that it was not possible to determine the amount or maximum size of cobbles or boulders encountered during the drilling program due to the type and size of sampling equipment used.

U.S. Army Corps of Engineers 2 Port of Anchorage, Alaska

Table 1: Trial Dredging Areas

Trial Dredging Area Dredging Contractor Reference Test Boring Exploration Log

TDA-1 J.E. McAmis, Inc. AP-4607

TDA-2 The Dutra Dredging Company AP-4611

TDA-3 The Dutra Dredging Company AP-4590

J.E. McAmis Trial Dredge Area 1 On 17 July 2008, J.E. McAmis used the Megan-Renee dredging barge and its Komatsu PC3000 Aquadigger excavator to dredge in the northern virgin dredge area near the location of test boring AP-4607. The Megan-Renee dredging barge was equipped with three 95-foot spuds to keep the barge in place while dredging. The excavator had a 10-cubic yard bucket and an approximate digging capability of 65 feet below the barge deck. Photograph 1 shows the barge and backhoe working at trial dredge area 1. Additional photographs of the McAmis dredging operations are presented in Appendix D.

Photograph 1: McAmis’s Megan-Renee dredging barge and Komatsu PC3000 Aquadigger.

U.S. Army Corps of Engineers 3 Port of Anchorage, Alaska

McAmis’s crew worked two 12-hour shifts at this location and dredged a total volume of approximately 7,940 cubic yards of material. Dredged material was loaded into the Sand Island split-barge dump scow and taken to the approved off-shore disposal site. The surface layer of gravel with silt, sand, and cobbles (GP-GM) was initially very difficult to break through. The volume of cobbles was estimated at 10 percent or less within this soil layer during the trial dredging.

Sand with silt (SP-SM) was encountered below the surface layer of gravel.

Photograph 2 shows an example of this soil unit encountered while dredging.

The estimated yield of material dredged in each 10-cubic yard bucket was between 80 to 100 percent (8 to 10 cubic yards in a 10-cubic yard bucket).

After a large dredging area was established, the side slopes of the excavation in the very dense sands with silt (SP-SM) began to slough to a limited extent into the area being excavated. Below the approximate elevation of -40 feet MLLW occasional layers of lean clay (CL) were encountered while dredging.

Boulders with a maximum dimension of six feet were encountered in trial dredge area 1. The estimated volume of boulders encountered while dredging was five percent or less. Photographs 2, 3, and 4 provide an example of the boulders encountered while dredging. This confirms that boulders are present within the proposed new work dredging areas. Survey information collected after the trial dredging was completed is provided in the Appendix B.

Photograph 2: Example of sand with silt (SP-SM) containing cobbles and boulders encountered at trial dredge area 1

(AP-4607).

U.S. Army Corps of Engineers 4 Port of Anchorage, Alaska

Photograph 4: Six-foot diameter boulder encountered while dredging at trial dredge area 1 (AP-4607).

Photograph 3: Boulders and cobbles encountered while dredging at trial dredge area 1 (AP-4607).

U.S. Army Corps of Engineers 5 Port of Anchorage, Alaska

The Dutra Dredging Company Trial Dredge Area 2 On 16 September 2008, The Dutra Dredging Company used the Paula Lee dredging barge with a crane and clam shell bucket to dredge in the southern virgin dredge near the location of test boring AP-4611. Photograph 5 shows the Paula Lee dredging barge and crane. Additional photographs of the Dutra dredging operations are presented in the Appendix D.

Photograph 5: Dutra’s Paula Lee dredging barge and crane.

The Paula Lee dredging barge was equipped with two spuds and four anchors to keep the barge in place while dredging. Dutra’s crew worked approximately 18 hours at this location and dredged a total volume of approximately 3,400 cubic yards of material. Dredged material was loaded into the split-barge Scow No. 5 and taken to the approved off-shore disposal site. Initially a 20-cubic yard Atlas clam-shell bucket weighing 30,000 pounds was used to remove the soft marine deposits of silt and silty sand (ML, SM) at the surface. The wet density of this soil was measured at 118.2 pounds per cubic foot. After the surface layer of soft or loose soils was removed, a 10-cubic yard Owens clam-shell bucket, weighing 54,000 pounds, was used to dredge the very dense clayey gravel with sand and cobbles (GC) encountered below the recent marine deposits. Photograph 6 shows the Owens 10-cubic yard bucket. Dredging the very dense clayey gravel with sand, cobbles, and boulders (GC) proved difficult;

the material recovered from each effort with the 10-cubic yard bucket was low with an estimated yield of 30 to 50 percent.

U.S. Army Corps of Engineers 6 Port of Anchorage, Alaska

Photograph 6: View of 10-cubic yard Owens clam-shell bucket weighing 54,000 pounds.

The wet density of this soil was measured at 128.6 pounds per cubic foot. The estimated volume of cobbles was 10 percent or less within this soil layer. A boulder with the approximate dimensions of 2 feet wide, 3 feet long, and 1 foot thick was dredged near elevation -25 feet MLLW. This boulder, shown in Photograph 7, had angular and fresh fractured faces indicating it was only a portion of a larger boulder. Firm lean clay (CL) was encountered below approximate elevation -28 feet MLLW. The wet density of this material was measured at 123.8 and 115.6 pounds per cubic foot. The material recovered during each effort with the 10-cubic yard bucket increased in the clay soils to an estimated yield of 70 to 100 percent. There was no difficulty in emptying the bucket and releasing the lean clay into the dump scow. The dredge area side slopes within the clay soils did not appear to slough while dredging.

Photograph 8 shows the lean clay encountered below -28 feet MLLW.

U.S. Army Corps of Engineers 7 Port of Anchorage, Alaska

Photograph 7: Boulder encountered while dredging near elevation -25 feet MLLW at trial dredge area 2 (AP-4611).

Photograph 8: Firm lean clay (CL) encountered below approximate elevation -28 feet MLLW while dredging at trial dredge area 2 (AP-4611).

U.S. Army Corps of Engineers 8 Port of Anchorage, Alaska

The Dutra Dredging Company Trial Dredge Area 3 On 23 September 2008, Dutra dredged near the location of test boring AP-4590 in the northern virgin dredge area. Dutra’s crew worked two 12-hour shifts at this location and dredged a total volume of approximately 2,000 cubic yards of material. Dredged material was loaded into the split-barge Scow No. 5 and taken to the approved off-shore disposal site. Dredging was very difficult;

initially the 20-cubic yard Atlas clam-shell bucket, weighing 30,000 pounds, was used with little or no recovery of material. This bucket was immediately replaced with the 10-cubic yard Owens clam-shell bucket weighing 54,000 pounds. The volume of material recovered from each 10-cubic yard bucket was very low with an estimated yield of 10 percent or less. Photograph 9 shows the typical amount of material recovered just below mud line. The wet density of gravel with silt, sand, and cobbles (GP-GM) encountered near the surface was measured at 148.4 pounds per cubic foot. The volume of cobbles at this location was estimated at 10 percent or less within this soil layer.

Photograph 9: Example of low material recovery using the 10-cubic yard Owens bucket while dredging near the surface at trial dredge area 3 (AP-4590).

Below the dense surface gravels the material changed to clayey sand with gravel and cobbles (SC) and clayey gravel with sand and cobbles (GC). The wet density of this material was measured between 125.2 and 144.6 pounds per cubic foot with an average density of 133.2 pounds per cubic foot. The estimated volume of cobbles was five percent or less within this soil layer.

U.S. Army Corps of Engineers 9 Port of Anchorage, Alaska

The material recovered from each bucket did increase with depth to an estimated yield between 10 and 40 percent. Photograph 10 shows an example of clayey gravel (GC) and clayey sand (SC) and the typical amount of material recovered using the 10-cubic yard Owens bucket. The dredge area side slopes within these soils did not appear to slough while dredging. Survey information collected after the trial dredging was completed is provided in Appendix C.

Photograph 10: An example of clayey gravel (GC) and/or clayey sand (SC) dredged at trial dredge area 3 (AP-4590).

Note the amount of material recovered in a typical pass with the 10-cubic yard Owens bucket.

SOILS AND GEOLOGY

CORPS OF ENGINEERS

ALASKA DISTRICT

CORPS OF ENGINEERS U.S. ARMY

ANCHORAGE HARBOR DEEPENING

NTS

MAY 2008

JR/CW

PORT OF ANCHORAGE, ALASKA

PROJECT LOCATION AND VICINITY MAP

EXISTING DREDGE LIMITS

EXIS

TIN

G D

REDGE LI

MITS

EXISTING DREDGE AREA

NORTHERN DREDGE AREA PROPOSED -45' DREDGE

PROPOSED -35' DREDGE

SOUTH BACKLANDS

SOUTH EXTENSION

2010 - 2011

SOUTH REPLACEMENT

2011 - 2012

NORTH REPLACEMENT

2010 - 2011

NORTH EXTENSION

2008 - 2009

BARGE BERTHS

2007 - 2009

TDA-3 / AP-4590 / Dutra

TDA-1 / AP-4607 / McAmis

TDA-2 / AP-4611 / Dutra

0 500 1000 2000

Trial dredging location with reference test boring number and contractor Scale (feet)Bathymetry taken 5 Oct 2007 (feet MLLW)

Photo Taken 17 September 2007

TDA-X / AP-XXXX / Contractor

ANCHORAGE HARBOR DEEPENING

TRIAL DREDGE AREA LOCATION MAP

CORPS OF ENGINEERS

ALASKA DISTRICT

SOILS AND GEOLOGY PORT OF ANCHORAGE, ALASKA

GRAPHIC

NOV 2008

JR/CW

APPENDIX A

EXPLORATION LOGS

Exploration Logs AP-4590, AP-4607, and AP-4611........................3 Pages

Lean CLAY

Clayey SAND with gravel

Clayey GRAVEL with Sand

Clayey GRAVEL with Sand

Clayey SAND with gravel

SILT with Gravel

Poorly graded GRAVEL with Silt and Sand

EXPLORATION LOG

Sa nd

Fin es

Lit ho log y

Sa mp le Re co ve ry

AS

TM

D

Fr oz en

E X

P

LO

R A

TI

O

N L

O G

A N

C H

O R

A G

E .G

P J

A C

E _A

N C

.G D

T

8/ 5/

Bl ow

C ou nt

0.75

CL

CL

SC

GC

GC

SC

ML

GP-

GM

50/5in.

0.5

1.25

>1.4

1.25

>1.4

0.5

Grey, wet, subangular to subrounded gravel, fine to coarse sand, medium plasticity fines, gravel fractured while driving

Bottom of Hole 38.5 ft.

Elevation -63.8 ft.

Drilled Below Water PID = (Cold/Hot) Photo Ionization Detector

Grey, wet, subangular gravel, fine sand, medium plasticity fines

Grey, wet, subangular to subrounded gravel, fine to coarse sand, medium plasticity fines, gravel fractured while driving

Jack-Up Barge Deck Elevation: 38.2 ft.

Grey, wet, subangular to subrounded gravel, fine to coarse sand, medium plasticity fines, gravel fractured while driving

Grey, wet, subangular to subrounded gravel, fine to coarse sand, medium plasticity fines, gravel fractured while driving

Grey, wet, subrounded gravel, fine sand, Atterberg Limits-Nonplastic

Grey, wet, subangular to subrounded gravel, fine to coarse sand, low plasticity fines, gravel fractured while driving

Grey, wet, subangular gravel, fine sand, medium plasticity fines

140 lbs

Total Depth:

Soils and Geology Section 29 Sep 2007

Date:

Top of Hole Elevation:

Vertical

Type of Hole:

Inspector:

Sy mb ol Test Pit

Type of Samples:

Project:

other

Walter Mahousky

4 in. I.D. x 4.5 in. O.D. HWT Casing

X

Split Spoon I.D.:

Monitoring Well

Permanent:

-25.3 ft.

Auger Hole

X

Operator:

Datum:

Anchorage Harbor Deepening

Project:

2,650,365 ft.

1,660,221 ft.

AP-4590

36.5 ft.

Mud Rotary

Inocencio Roman/Greg CarpenterTB-7

Page 1 of 1ALASKA DISTRICT

CORPS OF ENGINEERS

ENGINEERING SERVICES

Fr os t C las s.

ufc

3-

0-fa

F ine r

0.0 2m m

Classification ASTM: D 2487 or D 2488

Alaska District

Hole Number:

Ma x S ize (in

PI

D

(p pm

W ate r

Grain Size

Gr av el

De pth

(f t.)

Description and Remarks

Depth Drilled:

Other

Piezometer

Anchorage Harbor Deepening Port of Anchorage, Alaska

Mobile B-80 w/ Automatic Hammer1.375 in.

Horizontal

Hammer Weight: Size and Type of Bit: Type of Equipment:

Hole Number, Field:

MLLW

NAD83

* Indicates Estimated Frost Classification

38.5 ft.Drilled Below Water

Gregg Drilling / Fugro Jack-Up Barge

Drive

AP-4590

Location: Northing:

Easting:

Drilling Agency:

Depth to Groundwater:

Silty SAND

Silty SAND

Lean CLAY

Sa nd

Poorly graded SAND with Silt

Poorly graded SAND with Silt

Poorly graded SAND with Silt

Poorly graded GRAVEL with Silt and Sand

Poorly graded SAND with Silt

Fin es

Lit ho log y

Sa mp le Re co ve ry

AS

TM

D

Fr oz en

Jack-Up Barge Deck Elevation: 40.5 ft.

Bl ow

C ou nt

Sy mb ol

E X

P

LO

R A

TI

O

N L

O G

A N

C H

O R

A G

E .G

P J

A C

E _A

N C

.G D

T

1/ 4/

SM

CL

SP-

SM

SP-

SM

SM

SP-

SM

SP-

SM

GP-

GM

0.25

0.25

0.25

Grey, wet, fine to medium sand, NP fines

Bottom of Hole 39.0 ft.

Elevation -59.9 ft.

Drilled Below Water PID = (Cold/Hot) Photo Ionization Detector

Grey, wet, fine sand, NP fines

Grey, wet, Atterberg Limits-LL=27, PI=10

Grey, wet, fine to medium sand, NP fines, three inch layer of lean clay at 28 feet

Grey, wet, fine to medium sand, NP fines

Grey, wet, fine sand, NP fines

Grey, wet, subrounded gravel, fine to coarse sand, nonplastic (NP) fines

Grey, wet, fine to medium sand, NP fines

Top of Hole Elevation:

Datum: VerticalSoils and Geology Section

Type of Hole:

Inspector:

26 Sep 2007

Other

140 lbs Type of Samples:

X

EXPLORATION LOG

Alaska District

Test Pit

Drilling Agency:

Project:

Project:

Date:

Split Spoon I.D.:

Monitoring Well

Permanent:

-20.9 ft.

Auger Hole

X

Operator:

Total Depth:

Anchorage Harbor Deepening

2,649,256 ft.

1,660,382 ft.

AP-4607

37.0 ft.

Mud Rotary

Greg CarpenterTB-25

Piezometer

Ma x S ize (in

Fr os t C las s.

ufc

3-

0-fa

F ine r

0.0 2m m

Classification ASTM: D 2487 or D 2488

ALASKA DISTRICT

P

ID

(p pm

W ate r

Grain Size

Gr av el

De pth

(f t.)

Description and Remarks

Hammer Weight:

other

4 in. I.D. x 4.5 in. O.D. HWT Casing

Anchorage Harbor Deepening Port of Anchorage, Alaska

Mobile B-80 w/ Automatic Hammer1.375 in.

Horizontal

39.0 ft. Drilled Below Water

Gregg Drilling / Fugro Jack-Up Barge

CORPS OF ENGINEERS

ENGINEERING SERVICES

AP-4607 Walter Mahousky

Size and Type of Bit:

Depth to Groundwater:

Type of Equipment:

Depth Drilled:

MLLW

NAD83

* Indicates Estimated Frost Classification

Location: Northing:

Easting:

Hole Number:

Hole Number, Field:

Drive

SILT

Lean CLAY

Clayey GRAVEL with Sand

EXPLORATION LOG

Sa nd

Fin es

Lit ho log y

Sa mp le Re co ve ry

AS

TM

D

Fr oz en

Bl ow

C ou nt

Test Pit

NAD83

ML

CL

CL

GC 136 16

* Indicates Estimated Frost Classification

MLLW

Depth Drilled:

Type of Equipment:

Depth to Groundwater:

Size and Type of Bit:Hammer Weight:

4 in. I.D. x 4.5 in. O.D. HWT Casing

Walter Mahousky

Project:

E X

P

LO

R A

TI

O

N L

O G

A N

C H

O R

A G

E .G

P J

A C

E _A

N C

.G D

T

8/ 5/

Grey, wet, Atterberg Limits-LL=39, PI=15, 1.25 TSF indicated on pocket penetrometer

Bottom of Hole 34.3 ft.

Elevation -51.9 ft.

Drilled Below Water PID = (Cold/Hot) Photo Ionization Detector Vane Shear Test (VST): ASTM D2573 Vane Size(D x H): 55mmx110mm rectangular

Undrained Shear Strength = 1.034 kip/ft^2 Remolded Undrained Shear Strength = 0.496 kip/ft^2

Grey, wet, Atterberg Limits-Nonplastic, 1.5 TSF indicated on pocket penetrometer

50/0in.

Undrained Shear Strength = 1.636 kip/ft^2 Remolded Undrained Shear Strength = 0.685 kip/ft^2

Undrained Shear Strength = 1.558 kip/ft^2 Remolded Undrained Shear Strength = 0.587 kip/ft^2

Undrained Shear Strength = 1.403 kip/ft^2 Remolded Undrained Shear Strength = 0.649 kip/ft^2

Grey, wet, Atterberg Limits-LL=40, PI=18, 0.75 TSF indicated on pocket penetrometer

Grey, wet, angular to subangular gravel, fine to coarse sand, medium plasticity fines

Jack-Up Barge Deck Elevation: 32.2 ft.

Undrained Shear Strength = 1.945 kip/ft^2 Remolded Undrained Shear Strength = 0.634 kip/ft^2

Sy mb ol Type of Samples:

other

Operator:

X Alaska DistrictDrilling Agency:

Project:

Inspector:

-17.6 ft.

Piezometer

Permanent:

Monitoring WellAuger Hole

Anchorage Harbor Deepening

Split Spoon I.D.:

2,642,574 ft.

1,658,253 ft.

AP-4611

30.0 ft.

Mud Rotary

Robert WeaklandTB-29

Other

Total Depth:

Vertical

Type of Hole:

1.375 in.

Ma x S ize (in

Anchorage Harbor Deepening Port of Anchorage, Alaska

Fr os t C las s.

ufc

3-

0-fa

F ine r

0.0 2m m

Classification ASTM: D 2487 or D 2488

CORPS OF ENGINEERS

ENGINEERING SERVICES

PI

D

(p pm

W ate r

Grain Size

Gr av el

De pth

(f t.)

Description and Remarks

X

Horizontal

34.3 ft.Drilled Below Water

140 lbs

Datum:Soils and Geology Section 18 Sep 2007

Top of Hole Elevation:

Mobile B-80 w/ Automatic Hammer

Gregg Drilling / Fugro Jack-Up Barge

Drive

AP-4611

Location: Northing:

Easting:

Hole Number:

Hole Number, Field:

ALASKA DISTRICT

Date:

VST

VST

VST

VST

VST

APPENDIX B

MCAMIS TRIAL DREDGE AREA SURVEYS

J.E. McAmis Trial Dredge Area Surveys ........................................2 Pages

TEST DIG LOCATION

N 2,649,256 E 1,660,382

GRAPHIC SCALE

J.E McAMIS - U.S Army Corps of Engineers Port of Anchorage Expansion Test Dig

1-week Post-Dredge Hydrographic Survey

SURFACE TO SURFACE VOLUME REPORT

JEM - USACE Test Dig / Port of Anchorage Expansion / July 17, 2008

Final Dredge Quantity

Project: C:\Northwest Hydro\jobs\2008\08-013 JEM ICRC Anchorage\USACE Test Dig\ Tmodel\USACE Test Dig.pro Report Generated: Friday, July 18, 2008 10:05:19 AM Where the second surface is above the first the volume is reported as fill.

Where the second surface is below the first the volume is reported as excavation.

Shrinkage/swell factors: Excavation 1.0000 Fill 1.0000

First Surface Number Second Surface Number Layer Name of Points Layer Name of Points

PRE 17,224 POST 23,984

Volume limited to that within the constraining boundary - Object 41663 Area within boundary: 24,110.44 Sq. Ft. (0.5535 Acres) Total triangulated area: 24,110.48 Sq. Ft. (0.5535 Acres)

Excavation Volume (Cu. Yd.) Fill Volume (Cu. Yd.)

7,938.5

APPENDIX C

DUTRA TRIAL DREDGE AREA SURVEYS

The Dutra Dredging Company Trial Dredge Area Surveys..............4 Pages

APPENDIX D

TRIAL DREDGING PHOTOGRAPHS

Additional photographs of dredging operations..............................9 Pages

Trial Dredging Report APPENDIX D Anchorage Harbor Deeping U.S. Army Corps of Engineers Page 1 Port of Anchorage, Alaska

Photograph 11: McAmis’s Megan-Renee dredging barge at trial dredge area 1 (AP-4607).

Photograph 12: McAmis’s 10-cubic yard bucket used by the Komatsu PC3000 Aquadigger.

Trial Dredging Report APPENDIX D Anchorage Harbor Deeping U.S. Army Corps of Engineers Page 2 Port of Anchorage, Alaska

Photograph 14: Boulders encountered while dredging at trial dredge area 1 (AP-4607).

Photograph 13: Poorly graded sand with silt (SP-SM) encountered at trial dredge area 1 (AP-4607).

Trial Dredging Report APPENDIX D Anchorage Harbor Deeping U.S. Army Corps of Engineers Page 3 Port of Anchorage, Alaska

Photograph 16: Dutra’s 20-cubic yard Atlas clam-shell bucket weighing 30,000 pounds.

Photograph 15: Boulder encountered while dredging at trial dredge area 1 (AP-4607).

Trial Dredging Report APPENDIX D Anchorage Harbor Deeping U.S. Army Corps of Engineers Page 4 Port of Anchorage, Alaska

Photograph 17: Dutra’s 20-cubic yard Atlas clam-shell bucket heaped with soft marine deposits at trial dredge area

2 (AP-4611).

Photograph 18: Example of low recovery using the 10-cubic yard Owens bucket at trial dredge area 2 (AP-4611).

Trial Dredging Report APPENDIX D Anchorage Harbor Deeping U.S. Army Corps of Engineers Page 5 Port of Anchorage, Alaska

Photograph 20: Lean clay (CL) dredged at trial dredge area 2

(AP-4611).

Photograph 19: Clayey gravel with sand and cobbles (GC) dredged at trial dredge area 2 (AP-4611).

Trial Dredging Report APPENDIX D Anchorage Harbor Deeping U.S. Army Corps of Engineers Page 6 Port of Anchorage, Alaska

Photograph 21: Lean clay (CL) dredged at trial dredge area 2

Photograph 22: Lean clay (CL) dredged at trial dredge area 2

Trial Dredging Report APPENDIX D Anchorage Harbor Deeping U.S. Army Corps of Engineers Page 7 Port of Anchorage, Alaska

Photograph 23: Poorly graded gravel with silt, sand and cobbles (GP-GM) dredged at trial dredge area 3 (AP-4590).

Photograph 24: Poorly graded gravel with silt, sand and cobbles (GP-GM) (148.4 pounds per cubic foot) dredged at trial dredge area 3 (AP-4590).

Trial Dredging Report APPENDIX D Anchorage Harbor Deeping U.S. Army Corps of Engineers Page 8 Port of Anchorage, Alaska

Photograph 25: Clayey gravel with sand and cobbles (GC) dredged at trial dredge area 3 (AP-4590).

Photograph 26: Clayey gravel with sand (GC) (131.0 pounds per cubic foot) dredged at trial dredge area 3 (AP-4590).

Trial Dredging Report APPENDIX D Anchorage Harbor Deeping U.S. Army Corps of Engineers Page 9 Port of Anchorage, Alaska

Photograph 27: Clayey gravel with sand and cobbles (GC) dredged at trial dredge area 3 (AP-4590).