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Monitoring Cruise

at the Boston Lighthouse Disposal Site,

August 1 994



Disposal Area
Monitoring System
DAMOS









V-



DAMOS



DISPOSAL AREA MONITORING SYSTEM

Contribution 113
August 1996




'.„



US Army Corps
of Engineers

New England Division

TC
no. H3



I



REPORT DOCUMENTATION PAGE



Form approved
OMB No. 0704-0188



Public reporting concern for the collection of information is estimated to average 1 hour per persons inculding the time for reviewing
instructions, searching exsisting data sources gathering and measuring data needed and correcting and reviewing the collection of
information. Send comments regarding this burden estimate or any other aspect of this collection of information including
suggestions for reducing this burden to Washington Headquaters Services, Directoriate for Information Observations and Records,
1216 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302 and to the Office of Management and Support.



1. AGENCY USE ONLY (LEAVE BLANK)



2. REPORT DATE

August 1996



3. REPORT TYPE AND DATES

Final Report



4. TITLE AND SUBTITLE

MONITORING CRUISE AT THE BOSTON LIGHTSHIP DISPOSAL SITE, AUGUST 1994



6. AUTHORS

Ed DeAngelo



6. FUNDING NUMBERS



7. PERFROMING ORGANIZATION NAME(S) AND ADDRESS(ES)

Science Applications Intenational Corporation
22 lThrid Street
Newport, RI 02840



8. PERFORMING
ORGANIZATION REPORT

SAIC No. 328



9. SPONSORING/MONITORING AGENCY NAMES(S) AND ADDRESS(ES)

US Army Corps of Engineers-New England Division
424 Trapelo Road
Waltham, MA 02254-9 149



10. SPONSORING/
MONITORING AGENCY

DAMOS Contribution
Number 1 1 3



Avaiable from : DAMOS PROGRAM MANAGER Regulatory Division, USACE-NED

424 Trapelo Road
Waltham, MA 02254-9149



11. SUPPLEMENTARY NOTES



12a. DISTRIBUTION/A VAIABILTY STATEMENT

Approved for public release; distribution unlimited



12b. DISTRIBUTION CODE



13. ABSTRACT

Science Applications International Corporation (SAIC) conducted a reconnaissance REMOTS® sediment-
profile and plan view photographic survey of the Boston Lightship Disposal Site (BLDS) from 9 to 1 1 August 1 994. From the
1940's to 1976, when disposal stopped at BLDS, a majority of the Boston area's dredged material and other debris had been
released at this site. The last recorded disposal at this site was in 1 976 when about 8,000m3 were disposed. The REMOTS®
sediment-profile and plan view photographic stations were located to examine possible historic dredged material that had been
identified in a 1991 side-scan sonar survey of the area. The 1 994 surveys were conducted as part of a long-term effort to examine
historical disposal areas to determine whether remediation activity is recommended. The assessment of the REMOTS® and plan
view data, in conjunction with the 1991 side-scan results, determined that remediation at the site was not necessary.
Recolonization of old dredged material has been extensive. The benthos in the areas sampled was populated by a diverse
community composed of Stage II and Stage III organisms representing a healthy benfhic habitat with OSI values 3 6. No difference
was observed between the historic dredged material and the ambient sediment. In light of the healthy benthic habitat, only
periodic monitoring is recommended. Sediment samples were collected at BLDS in 1994. They were archived and are available
for analysis.

The REMOTS® sediment-profile and plan view photographic surveys were also conducted to gather information
on the area's sedimentary environment. This information would determine if the BLDS was suitable to potentially receive dredged
material from the Boston Harbor Navigation Improvement Project and Berth Dredging Project. The 1991 side-scan sonar survey
had mapped areas of circular or track-like dredged material patterns at the site. The use of the area for dredged material disposal
was consistent with its characterization as depositional or nonerosive (Knebel 1993). By focusing on the areas of dredged material
disposal with the REMOTS® sediment-profile and plan view photographic survey, the reconnaissance effort produced no evidence
to preclude the future use of BLDS for dredged material disposal. The major modal grain size was the silt/clay size class (>4 phi)
with very fine sands found in the surface sediments. Evidence of sediment resuspension was limited primarily to winnowing of
silts/clays from surface sediments.

The assessment of BLDS was efficiently accomplished by basing the REMOTS® sediment-profile and plan
view photographic survey on the results of the previous side-scan survey. The combined data sources provided a broad picture of
the status of the historical dredged material which has been at the disposal site for more than 20 years. Based on the 1994 survey
results, remediation is not necessary for BLDS, and the depositional environment does not preclude its use as a disposal area.



14. SUBECT TERMS

Boston Lightship Disposal Site (BLDS) , Boston Harbor Improvement Project , benthic habitat,

Remote Monitoring of the Seafloor (REMOTS) , dredged material, nonerosive or depositional



15.NUMBER OF PAGES

31



16. PRICE CODE



17. SECURITY CLASSIFICATION OF REPORT

UNCLASSIFIED



18. SECURITY CLASSIFICATION
OF THIS PAGE



19. SECURITY CLASSIFICATION
OF ABSTRACT



20.LIMITATION OF
ABSTRACT



MONITORING CRUISE AT THE

BOSTON LIGHTHOUSE DISPOSAL SITE

AUGUST 1994



CONTRIBUTION #113



August 1996

Report No.
SAIC No. 328



Submitted to:

Regulatory Division

New England Division

U.S. Army Corps of Engineers

424 Trapelo Road

Waltham, MA 02254-9149

Prepared by:
Ed DeAngelo

Submitted by:

Science Applications International Corporation

Admiral's Gate

221 Third Street

Newport, RI 02840

(401)847-4210



US Army Corps
of Engineers

New England Division



MONITORING CRUISE AT THE HISTORIC

BOSTON LIGHTSHIP DISPOSAL SITE

AUGUST 1994



24 July 1996



Contract No. DACW33-93-D-0002

Work Order 21, Task 2

SAIC Report No. 328



Submitted to:

New England Division
US Army Corps of Engineers

424 Trapelo Road
Waltham, MA 02254-9149

Prepared by:

Ed DeAngelo

Submitted by:

Science Applications International Corporation

Admiral's Gate

221 Third Street

Newport, RI 02840

(401) 847-4210



TABLE OF CONTENTS



Page

LIST OF TABLES iii

LIST OF FIGURES iv

EXECUTIVE SUMMARY vi

1.0 INTRODUCTION 1

2.0 METHODS 5

2. 1 REMOTS® Sediment-Profile and Plan View Photography 5

2.2 Sediment Sampling 5

2.3 Navigation 8

3.0 RESULTS 9

3.1 REMOTS® Sediment-Profile Photography 9

3.1.1 Presence of Dredged Material 9

3.1.2 Grain Size Distribution 9

3.1.3 Apparent Redox Potential Discontinuity (RPD) Depth 9

3.1.4 Successional Stage 14

3.1.5 Organism-Sediment Index 14

3.2 Plan View Photography 14

4.0 DISCUSSION 24

4. 1 The Sedimentary Environment of BLDS 24

4.2 Presence of Dredged Material 26

4.3 Benthic Recolonization 27

5.0 CONCLUSION 29

6.0 REFERENCES 30

INDEX
APPENDIX



LIST OF TABLES



Page
Table 2- 1 . Station Target Locations for REMOTS® Sampling at BLDS 7



LIST OF FIGURES



Page

Figure 1 - 1 . Site location map of the Boston Lightship Disposal Site 2

Figure 1-2. The relative locations of dredged material located by side-scan
sonar; 1994 REMOTS® sampling transects; a depositional
sedimentary environment above the 50 m depth contour; and
a proposed disposal location 4

Figure 2-1 . REMOTS® sampling transects 6

Figure 3-1. The number of stations per transect where dredged material was

observed in the REMOTS® images 10

Figure 3-2. Light gray, high reflectance Boston Blue Clay located at Stations

C3-10 (A) and C2-7 (B) 11

Figure 3-3 . Layer of biogenically reworked sediments over dredged material

and large Stage III polychaete feeding in the dredged material layer 12

Figure 3-4. Transect average apparent redox potential discontinuity depths (cm) 13

Figure 3-5 . Example of a thick RPD (4 cm) observed at Station C3-1 15

Figure 3-6. Surface sediments at BLDS colonized by Stage II

"stick-building" amphipods (Family Podocerdiae; A) and

Stage III tube-dwelling polychaetes (B) 16

Figure 3-7. Water-filled feeding void below the RPD at Station C6-4 17

Figure 3-8. Bioturbating caudate holothurian Molpadia oolitica at Station C2-10 18

Figure 3-9. Transect average Organism-Sediment Index values 19

Figure 3-10. Summary of bottom features observed in plan view photographs 20

Figure 3-11. Possible construction debris— large, sharp-angled, silt-covered
rocks observed in plan view photographs from transects CI (A)
andC4(B) 22

iv



LIST OF FIGURES (continued)



Page

Figure 3-12. Heterogeneous distribution of surface polychaete tubes ranging

from a dense carpet (A) to nearly absent (B) 23

Figure 4-1 . Location of depositional environments in Massachusetts Bay from the

shore to the 50 m depth contour 25



EXECUTIVE SUMMARY



Science Applications International Corporation (SAIC) conducted a reconnaissance
REMOTS® sediment-profile and plan view photographic survey of the Boston Lightship
Disposal Site (BLDS) from 9 to 11 August 1994. From the 1940s to 1976, when disposal
stopped at BLDS, a majority of the Boston area's dredged material and other debris had
been released at the site. The last recorded disposal at the site was in 1976 when about
8,000 m 3 were disposed. The REMOTS® sediment-profile and plan view photographic
stations were located to examine possible historic dredged material that had been identified
in a 1991 side-scan sonar survey of the area. The 1994 surveys were conducted as part of
a long-term effort to examine historical disposal areas to determine whether remediation
activity is recommended. The assessment of the REMOTS® and plan view data, in
conjunction with the 1991 side-scan results, determined that remediation at the site was not
necessary. Recolonization of old dredged material has been extensive. The benthos in the
areas sampled was populated by a diverse community composed of Stage II and Stage III
organisms representing a healthy benthic habitat with OSI values >6. No difference was
observed between the historic dredged material and the ambient sediment. In light of the
healthy benthic habitat, only periodic monitoring is recommended. Sediment samples were
collected at BLDS in 1994. They were archived and are available for analysis.

The REMOTS® sediment-profile and plan view photographic surveys were also
conducted to gather information on the area's sedimentary environment. This information
would determine if the BLDS was suitable to potentially receive dredged material from the
Boston Harbor Navigation Improvement Project and Berth Dredging Project. The 1991
side-scan sonar survey had mapped areas of circular or track-like dredged material patterns
at the site. The use of the area for dredged material disposal was consistent with its
characterization as depositional or nonerosive (Knebel 1993). By focusing on the areas of
dredged material disposal with the REMOTS® sediment-profile and plan view photographic
survey, the reconnaissance effort produced no evidence to preclude the future use of BLDS
for dredged material disposal. The major modal grain size was the silt/clay size class
(>4 phi) with very fine sands found in the surface sediments. Evidence of sediment
resuspension was limited primarily to winnowing of silts/clays from surface sediments.

The assessment of BLDS was efficiently accomplished by basing the REMOTS®
sediment-profile and plan view photographic survey on the results of the previous side-scan
survey. The combined data sources provided a broad picture of the status of the historical
dredged material which has been at the disposal site for nearly 20 years. Based on the
1994 survey results, remediation is not necessary for BLDS, and the depositional
environment does not preclude its use as a disposal area.



1.0 INTRODUCTION

The consideration of BLDS as an alternative site for future disposal operations
(Normandeau Associates 1994) and the existence of an extensive data set on observed
dredged material at the site (Schoenherr et al. 1992) provided impetus for the study
described here. A reconnaissance survey of the Boston Lightship Disposal Site (BLDS), a
currently inactive site located 16 nmi east of Boston (Figure 1-1), was conducted under the
Disposal Area Monitoring System (DAMOS) Program as part of a long-term effort to
investigate historical disposal areas. From the 1940s to 1976, when disposal stopped at
BLDS, a majority of the Boston area's dredged material and other debris had been released
at the site. During the late 1960s and early 1970s, BLDS received approximately
2.3 million m 3 of material dredged from Boston Harbor (Normandeau Associates 1994).
Disposal at the site was directed toward the Dumping Ground (DG) buoy. However, the
buoy location only served as a general guide for the barges and was not used for point
dumping. Although disposal activity was concentrated in an area surrounding the buoy,
material was apparently disposed throughout the site.

Prior to the early 1970s, the oversight of the nature and placement of disposed
materials was less stringent than at present. The US Army Corps of Engineers, New
England Division (NED), has initiated a cooperative effort to investigate historical disposal
sites, whenever possible, to determine existing environmental conditions. One potential
remediative activity might be to use present disposal activities to cover old deposits.

Science Applications International Corporation (SAIC) conducted short (9-11
August 1994) REMOTS® sediment-profile and plan view photographic surveys of small
areas within the disposal area. These areas were deemed likely to contain dredged material
based on a previous side-scan survey. The primary objective of the survey was to explore
the need for dredged material remediation. The relative health of the benthic environment
was determined by the recolonization status of relic dredged material compared to results
obtained from ambient sediment. The secondary objective was to determine if there was
any evidence to preclude future use of the site for dredged material disposal. Small scale
sediment characteristics in the REMOTS® and plan view photographs, in conjunction with
features identified in the side-scan records, were examined to determine if the sedimentary
environment was suitable for future dredged material disposal.

Until recently, little was known regarding the location and nature of the material
that had been disposed at BLDS. In 1991, the US Environmental Protection Agency
(EPA) sponsored a side-scan and Remotely Operated Vehicle (ROV) survey of BLDS.
SAIC supported efforts to locate, identify, and determine the condition of waste containers
in the area (Schoenherr et al. 1992). Interpretation of the side-scan records over a 16 nmi 2

Monitoring Cruise at the Historic Boston Lightship Disposal Site, August 1994



Massachusetts Bay, Massachusetts




GLOUCESTER



MANCHESTER _ , - Shore Station

SALES POINT



42°30' N




BOSTON



MARBLEHEAD




SCITUATE



SEREF




Boston Lightship
Disposal Site



Massachusetts Bay



nmi



8 12 km



Figure 1-1. Site location map of the Boston Lightship Disposal Site. The Boston

Lightship Disposal Site is located approximately 16 nmi east of Boston, MA.



Monitoring Cruise at the Historic Boston Lightship Disposal Site, August 1994



area (Figure 1-2) located 469 dredged material targets in addition to 43 potential waste
barrel fields, and 136 debris fields. Dredged material targets generally appeared on the
side-scan records as circular or track-like patterns of sediment with a marked contrast to
the surrounding natural sediments. While the dredged material targets were scattered
throughout the disposal area, high concentrations were located in a ring around the former
DG buoy location and to the south of the buoy beyond the 50 m depth contour. In the
1994 reconnaissance survey, the REMOTS® and plan view photography station locations
corresponded to areas of dense dredged material targets. This sampling scheme supported
the primary objective of the survey by maximizing the probability of collecting data from
relic dredged material where the potential need for remediation would be the greatest.

A secondary objective of the present survey was to characterize the dominant
processes controlling the sedimentary environment and to determine the suitability of the
area for potential future disposal. The area greater than 50 m depth at BLDS has been
suggested as a potential site for future disposal, such as 0.9 million m of silty maintenance
material from the proposed Boston Harbor Navigation Improvement Project and Berth
Dredging Project (Normandeau Associates 1994). This material would be capped with
approximately one meter of parent material that lies under the silts of Boston Harbor.
Approximately half of BLDS lies below the 50 m depth contour on the slope of Stellwagen
Basin. Based on the sedimentary fabric observed in the REMOTS® and plan view
photographs, it was determined that below the 50 m contour BLDS is primarily a
depositional environment and that there is no evidence to preclude its use for the deposition
of silty dredged material.



Monitoring Cruise at the Historic Boston Lightship Disposal Site, August 1994




42°15'



Figure 1-2. The relative locations of dredged material located by side-scan sonar

(Schoenherr et al. 1992); 1994 REMOTS® sampling transects; a depositional
sedimentary environment above the 50 m depth contour (Knebel 1993); and a
proposed disposal location (Normandeau Associates 1994)



Monitoring Cruise at the Historic Boston Lightship Disposal Site, August 1994



2.0 METHODS

2.1 REMOTS® Sediment-Profile and Plan View Photography

The August 1994 REMOTS® sediment-profiling survey was conducted along six
transects labeled CI through C6. Transects CI, C3, C4, and C5 surrounded the DG buoy,
and transect C2 was south of the buoy in an area of dense dredged material targets. This
allowed us to maximize the potential of encountering dredged material (Figures 1-2 and 2-
1) and to focus on depositional areas determined suitable for future disposal (Normandeau
Associates 1994). Transect C6 was situated in an area where side-scan records did not
contain any targets interpreted as dredged material in order to assess benthic recolonization
on ambient sediments located within BLDS. Two of the transects, CI and C6, were
oriented north to south while the remainder were oriented east to west. Each transect was
500 m long and consisted of ten stations spaced 50 m apart (a total of 60 stations; Table 2-
1). Two replicate photographs were taken at each station.

Surficial sediments were photographed with a Photosea submersible plan view
camera to permit evaluation of surface features including benthic animals and
sedimentological features. The plan view camera was attached to the REMOTS® camera
frame and photographed the sediment surface prior to camera frame touch-down in order
to record an image of undisturbed sediments.

2.2 Sediment Grab Sampling

Sediment samples were collected with 0.1 m van Veen grab sampler at three of the
six transects (C2, C3, and C4) and at the reference area FG-23. Grab samples were
collected at Stations 1, 5, and 10 (Table 2-1) of each transect for a total of nine grabs.
Three replicate samples were collected at the reference area.

Once the grab was brought aboard, four to five subcores were collected for
chemical analysis, and the remaining sediment was saved for benthic community analysis.
The chemistry subsample was composited in a teflon container and subsampled again for
polycyclic aromatic hydrocarbons (PAHs), metals, and grain size/total organic carbon
(TOC) analysis. The PAHs and metal subsamples were each placed in pre-cleaned 110 ml
I-CHEM jars, and the grain size/TOC subsamples were stored in ziplock plastic bags.

The remaining sediment set aside for benthic community analysis was sieved
through a 500 micron screen. The residue was placed in one liter nalgene jars with both
internal and external labels. Each biological sample was fixed in 10% formalin and stained
with rose bengal, an organic stain. Following field collection, all sediment samples,

Monitoring Cruise at the Historic Boston Lightship Disposal Site, August 1994



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Monitoring Cruise at the Historic Boston Lightship Disposal Site, August 1994



biological and chemical, with the proper chain of custody forms were delivered to the US
Army Corps of Engineers, New England Division (NED) laboratory where the samples
were archived.

2.3 Navigation

Navigation for the survey was provided by an SAIC Portable Integrated Survey
System (PINSS). The PINSS is a PC-based system that receives navigation data,
mathematically weights these signals based on signal strength (via a Kalman filter), and
calculates both the position of the ship and the position error. The PINSS was interfaced
to a Magnavox MX4200 Global Positioning System (GPS) with a Magnavox MX50R
Differential-GPS (DGPS) receiver for vessel positioning with an accuracy of ±5 m.



Monitoring Cruise at the Historic Boston Lightship Disposal Site, August 1994



3.0 RESULTS

3 . 1 REMOTS® Sediment-Profile Photography

3.1.1 Presence of Dredged Material

Dredged material was observed at five of the six transects sampled (Figure 3-1;
Appendix). Dredged material in the REMOTS® photographs appeared in two forms: 1)
dark silty material typically found in dredged material throughout New England and 2)
Boston Blue Clay (Figure 3-2, A and B). Boston Blue Clay, formed from silt and clay
particles in glacial melt water, is a common constituent of material dredged from Boston
Harbor (Camp, Dresser, and McKee, Inc. 1991). In most cases dredged material appeared
as a horizon below a sandy mud layer of reworked sediments several centimeters thick and
extended below camera penetration (Figure 3-3). However, in two instances (Figure 3-2,


1 3

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