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Monitoring Cruise at the Morris Cove Borrow Pit

Disposal Area
Monitoring System
DAMOS

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DATA i B RA RY

Woods Hole Oceanographic Institution |

DAM OS
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DISPOSAL AREA MONITORING SYSTEM

Contribution 129
June 2001

US Army Corps
of Engineers «
New England District

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1OHM/18lN

form approved
OMB No. 0704-0188

REPORT DOCUMENTATION PAGE

Public reporting concern for the collection of information is estimated to average | hour per response including the time for reviewing instructions,
searching existing data sources, gathering and measuring the 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
Headquarters Services, Directorate for information Observations and Records, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302
and to the Office of Management and Support, Paperwork Reduction Project (0704-0188), Washington, D.C. 20503.

1. AGENCY USE ONLY (LEAVE BLANK) |2. REPORT DATE 3. REPORT TYPE AND DATES COVERED
June 2001 FINAL REPORT

5. FUNDING NUMBERS

4. TITLE AND SUBTITLE
Monitoring Cruise at the Morris Cove Borrow Pit

6. AUTHOR(S)
Science Applications International Corporation

8. PERFORMING
ORGANIZATION REPORT
NUMBER

SAIC No. 520

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)
Science Applications International Corporation
221 Third Street

Newport, RI 02840

10. SPONSORING/MONITORING
AGENCY REPORT NUMBER
DAMOS Contribution Number 129

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)
US Army Corps of Engineers-New England District
696Virginia Rd

Concord, MA 01742-2751
11. SUPPLEMENTARY NOTES
Available from DAMOS Program Manager, Regulatory Branch
USACE-NAE, 696 Virginia Rd, Concord, MA 01742-2751

12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

Approved for public release; distribution unlimited

13. ABSTRACT
During January and May 2000, an estimated total of 14,200 m? of sediment dredged from the U.S. Coast Guard Base in New Haven, CT was placed in a small, man-made
depression (borrow pit) in Morris Cove, located in outer New Haven Harbor. A monitoring survey was conducted over the Morris Cove borrow pit in late September 2000
to document the distribution of the dredged material on the seafloor, verify the stability of the sediment deposit, and evaluate recolonization of the deposit by benthic
organisms. The monitoring involved the use of REMOTS® sediment-profile imaging, side-scan sonar, single-beam bathymetry, and towed video to evaluate benthic
conditions within and adjacent to the borrow pit. Sediment-profile images also were obtained at a reference area located approximately 800 m west of the borrow pit to
provide a comparison with ambient seafloor conditions.

The side-scan sonar data showed a clear differentiation between softer sediments within the borrow pit and coarser, more compact sediments comprising the outer walls of
the pit. Multiple bottom features with increased vertical relief and surface roughness detected within a 50 mradius of the central disposal point and to the east of this point
were attributed to dredged material deposition. Both the side-scan sonar and towed video data suggested that the impacts associated with the deposition of dredged
material were contained largely within the southern portion of the Morris Cove borrow pit. The controlled placement of small barge loads of dredged material had
facilitated the creation of a small-scale sediment deposit within the confines of the pit. The REMOTS® sediment-profile images served to confirm the presence of dredged
material at stations located within the borrow pit. The dredged material was observed at stations in close proximity to the disposal buoy position and extending out 100 to
150 m from this central disposal point. The measured thickness of the dredged material layer typically exceeded the penetration depth of the sediment-profile camera (i.e.,
greater than about 10 or 15 cm). The dredged material was predominantly fine-grained, consisting of soft, sandy silt.

the reference area. It was hypothesized that the shallow reference area may experience periodic physical disturbance from fishing activities or the scouring action of waves
and currents during high wind events.

At the time of the survey (5 months post disposal), it appeared that benthic recolonization of the dredged material deposit was progressing as expected. The sediment-
profile images showed that the benthic infauna included primarily Stage I opportunistic polychaetes (i.e., pioneering taxa) at the sediment surface. Relatively
well-developed redox depths were noted at most stations, and advanced successional stages (Stages II and/or III) were observed at 8 of the 22 stations occupied. Due to
the protected nature of the borrow pit and the recent input of organically enriched sediment, overall benthic habitat quality within the borrow pit was considered to be
better than that at the nearby, shallow reference area.

14. SUBJECT TERMS Morris Cove, New Haven Harbor, Borrow Pit, Dredged Material

17. SECURITY CLASSIFICATION OF |18. SECURITY CLASSIFICATION
REPORT Unclassified OF THIS PAGE

15. NUMBER OF TEXT PAGES: 38

16. PRICE CODE

19. SECURITY CLASSIFICATION |20. LIMITATION OF
OF ABSTRACT ABSTRACT

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MONITORING CRUISE
AT THE MORRIS COVE
BORROW PIT

CONTRIBUTION #129

June 2001

Contract No.
DACW33-00-D-0001
SAIC Report No. 520

Submitted to:

Regulatory Branch
New England District
U.S. Army Corps of Engineers
696 Virginia Road
Concord, MA 01742-2751

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 District

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TABLE OF CONTENTS

Page
LISMORE AB IER S 50.001 SOR ORR RIA NS OEE FE RIS IVE OE TEN OU ccc beseoeensee iii
LIST OF FIGURES tin LY ERA) CIRO SBS OO a ce ncpcane sn enarsouessetesietaseceteneareeercaeresiacteeee iv
PGE CUAIVIES SWMINTAIR IY pes eee For sec oe ace sie cu ecu cater Mess te cn cmisaeebantetess us els, aal uate vi
[LOM OBIE GHVE ORshEHE MONITORING: SWRI eerste tenes eee nee 1
One MIE THOD SIL S08 RUURAS A RE Pe Se, CU EAS OE Be US AEE etches ria 4
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82 REMOMS= Sediment-Profilelmacingessie etme ee ce eee 13
3.2.1 Dredged Material Distribution and Physical Sediment
Characteristics vese succor ol ess cones, oath eed daccatbed tases anaaddcdoueau ed lasieaaluauete 18
3.2.2 Biological Conditions and Benthic Recolonization..................0::0:0 22
B23 Mllowed) Video SUnVveyeneisccetctiacstee seas sas cee teccsue ce cez cavdemeeescaeany eae ce sseeneeaeee Nee 28
3:3. 1") Sediment Composition). i....22 22.5. seoveccdsc sce sseceosercsuces oes eevseesetesuseseteeeee ec 28
3.3.2. Benthic Macrofauna jecc...2c2..chavecoccesctses eocecevoncersocerevaczavest res ce cse seat 36
Aves CONCLUSIONS reo iccctescascncsercdsnce dave: setts aoe craus oes Basen ene Gant cea oeaeen ane 37
OMe REFEREIN GES ix. ir cise ce assessor ssa «acco niece a cae te oan smo seucetetante ta ae eae cage onan 38
INDEX
APPENDICES

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LIST OF TABLES

Table 1-1.

Table 2-1.

Table 3-1.

Table 3-2.

Page
Summary of disposal operations over the Morris Cove borrow pit
during the, 1999-2 00Oidisposaliseas Om cs. eee} secession wesc cs nceesess 2)
Morris Cove borrow pit REMOTS® Sampling Locations.................cccscccceeees 7
REMOTS® SUMMARY TABLE FOR THE MORRIS COVE
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Figure 1-1.

Figure 2-1.

Figure 2-2.

Figure 2-3.

Figure 2-4.

Figure 3-1.

Figure 3-2.

Figure 3-3.

Figure 3-4.

Figure 3-5.

Figure 3-6.

Figure 3-7.

LIST OF FIGURES

Page
Location of the Morris Cove borrow pit, central disposal point
(MCDA buoy), and Morris Cove Reference Area, relative to the
East Haveli Shonehime ae, S98 See POOU NOOR: MANNE RIE Te We eye 3

Longitudinal survey lines occupied over the Morris Cove borrow pit for the
collectiontof side-scan! Sonar datas) -e eee se Aa eer eee eee 5

Schematic diagram of a Benthos Inc. Model 3731 REMOTS® sediment-
profile camera and sequence of operation on deployment....................... 8

REMOTS® Sediment-Profile Photography Stations established over
the: Morris Cove DOnmOW: Pitan. .sc4co corte ease cee ones os eer eee 9

Track lines for longitudinal transects and transverse transects occupied
Withpthe Video towliSht oii cana ieee cect ee Aces Anes ea uma eee Aen een 11

Side-scan sonar mosaic of the three lanes occupied over the Morris Cove
DOTTOW§D biicect Seeg hehe oaks atin Aauet® ak Hadas a Saaermeemces bering ie siotott os 16

Side-scan sonar image displaying several acoustically detectable
bottom features within the Morris Cove borrow pit in close proximity
foytheyMED Ay buoy positiontsom et eee eee eo gacaek ae -- NW

Map showing the average thickness of the dredged material layer
observed in replicate sediment profile images at each station ................. 19

REMOTS® image from station 100SW within the Morris Cove borrow

pit, showing a layer of fine-grained dredged material extending from the
sediment-water interface to below the imaging depth of the camera (i.e.,
dredged material greater than penetration).....................c0ccecceeeeeeeeeees 20

REMOTS® images from stations REF4 (left) and REF5 (right)
illustrating the relatively soft, fine-grained sediment (grain size major
mode of >4 phi) which characterized the reference area stations ............ Dill

Map showing average RPD and OSI values at each borrow pit station ...... 23

Map showing infaunal successional stages present at each borrow pit
SUAMOMN: ohare Sacto erieaaeie Lc muetieiin Gc atl ehe eae RE aA ME TEe men eee eae ee eee ee 24

LIST OF FIGURES (continued)

Figure 3-8.

Figure 3-9.

Figure 3-10.

Figure 3-11.

Figure 3-12.

Figure 3-13.

Figure 3-14.

Figure 3-15.

Page
REMOTS® image showing small, tubicolous, opportunistic
polychaetes (Stage I) present at the surface of fine-grained dredged
material at station 1OOSW within the borrow Pit ...............:ceeseeeseeeceesseeeeeees 25
REMOTS® images from station 50E (left) and 150S (right) showing
Stage I and II tubes visible at the sediment surface, and feeding voids
(evidence of Stage III activity) at depth within the sediment......................0. Di

Aerial perspective and profile view of surface sediment characterization
data obtained for Transect A displaying distribution of fine sand (yellow),
silt (magenta), shell lag (tan), rock (black) and macrophytic algae (gray)...... 29

Aerial perspective and profile view of surface sediment characterization
data obtained for Transect B displaying distribution of fine sand (yellow),
silt (magenta), shell lag (tan), rock (black) and macrophytic algae (gray)...... 30

Aerial perspective and profile view of surface sediment characterization
data obtained for Transect C displaying distribution of fine sand (yellow),
silt (magenta), shell lag (tan), rock (black) and macrophytic algae (gray)...... 31

Aerial perspective and profile view of surface sediment characterization
data obtained for Transect D displaying distribution of fine sand (yellow),
silt (magenta), shell lag (tan), rock (black) and macrophytic algae (gray)...... 32

Aerial perspective and profile view of surface sediment characterization data
obtained for Transect F displaying distribution of fine sand (yellow), silt
(magenta), shell lag (tan), and macrophytic algae (gray). ...........::ccessceseereees 33

Aerial perspective of towed video Transects A through G showing
agreement in sediment classification between overlapping and closely
Spaced track limes: -sAnecenceece seas ae eke casc ers setae sact eens hesoaaygaasesoeceeeeeeenemene 34

EXECUTIVE SUMMARY

During January and May 2000, an estimated total of 14,200 m° of sediment dredged
from the U.S. Coast Guard Base in New Haven, CT was placed in a small, man-made
depression (borrow pit) in Morris Cove, located in outer New Haven Harbor. A monitoring
survey was conducted over the Morris Cove borrow pit in late September 2000 to document
the distribution of the dredged material on the seafloor, verify the stability of the sediment
deposit, and evaluate recolonization of the deposit by benthic organisms.

The monitoring involved the use of REMOTS® sediment-profile imaging, side-scan
sonar, single-beam bathymetry, and towed video to evaluate benthic conditions within and
adjacent to the borrow pit. Sediment-profile images also were obtained at a reference area
located approximately 800 m west of the borrow pit to provide a comparison with ambient
seafloor conditions.

The REMOTS® sediment-profile images served to confirm the presence of dredged
material at stations located within the borrow pit. The dredged material was observed at
stations in close proximity to the disposal buoy position and extending out 100 to 150 m
from this central disposal point. The measured thickness of the dredged material layer
typically exceeded the penetration depth of the sediment-profile camera (i.e., greater than
about 10 or 15 cm). The dredged material was predominantly fine-grained, consisting of
soft, sandy silt.

The presence of methane gas bubbles in the sediment at three stations within the
borrow pit suggested that some of the dredged material continues to contain a high inventory
of organic matter. Fine-grained sediments having relatively high surface boundary
roughness, shell lag deposits, and shallow depth of aeration characterized the reference area.
It was hypothesized that the shallow reference area may experience periodic physical
disturbance from fishing activities or the scouring action of waves and currents during high
wind events.

At the time of the survey (5 months post disposal), it appeared that benthic

recolonization of the dredged material deposit was progressing as expected. The sediment-
profile images showed that the benthic infauna included primarily Stage I opportunistic

EXECUTIVE SUMMARY (continued)

polychaetes (i.e., pioneering taxa) at the sediment surface. Relatively well-developed redox
depths were noted at most stations, and advanced successional stages (Stages II and/or II)
were observed at 8 of the 22 stations occupied. Due to the protected nature of the borrow pit
and the recent input of organically enriched sediment, overall benthic habitat quality within
the borrow pit was considered to be better than that at the nearby, shallow reference area.

1.0 OBJECTIVE OF THE MONITORING SURVEY

During the 1999/2000 disposal season, a small dredging project was completed at the
U.S. Coast Guard Base in New Haven Harbor, East Haven, Connecticut. A total barge
volume of 14,200 m3 of sediment deemed suitable for unconfined open water disposal was
removed from the berthing areas to improve the efficiency of operations within the boat
basin. Normally, these sediments would be transported to the Central Long Island Sound
Disposal Site (CLIS) and incorporated within an active disposal mound on the seafloor.
However, recent interest in alternative uses for dredged material and innovative disposal
methods prompted a change in management strategy for these sediments.

A small, man-made bottom depression, or borrow pit, located in Morris Cove was
selected as an alternate disposal site for the USCG sediments. The borrow pit was created
several decades ago when sand and gravel were mined for use as fill for the construction of
Interstate Highway 95 through New Haven. The ambient sediments were excavated along a
north-northwest to south-southeast axis, resulting in a submerged pit approximately 200 m
wide and 750 m in length (Figure 1-1). Currently, water depths at the borrow pit range from
3 mto 12m. The deepest areas of the pit are upwards of 8 m deeper than the surrounding
ambient seafloor, suggesting a substantial capacity that could be utilized for the deposition of
dredged sediments.

In early January 2000, a small disposal buoy (MCDA) was placed at 41° 15.644°N,
72° 53.972” W in the southern region of the borrow pit (Figure 1-1). An estimated 10,400 m?
of dredged material was deposited at the buoy during January 2000, before the dredging
operation was interrupted by heavy ice in the harbor. Dredging and disposal operations were
reinstated on 2 May and continued through 15 May, with an additional 3,800 m3 of material
deposited at the MCDA buoy (Table 1-1; Appendix A).

A monitoring survey was conducted over the Morris Cove borrow pit in late
September 2000 (5 months post-disposal) to:

e document the distribution of the dredged material on the seafloor;

e verify the stability of the sediment deposit; and

e examine benthic recolonization over the new sediment deposit, relative to ambient
New Haven Harbor sediments.

Monitoring Cruise at the Morris Cove Borrow Pit

Table 1-1
Disposal Log Summary Table

Disposal Site MORRIS COVE
Project Channel & Dock Area
Permit Number 199901985
Permittee U.S. Coast Guard

01/10/00 | 01/10/00 | 01/10/00
01/11/00 | 01/11/00 | 01/11/00
01/12/00 | 01/12/00 | 01/12/00
01/13/00 | 01/13/00 | 01/13/00
01/13/00 | 01/13/00 | 01/13/00
01/13/00 | 01/13/00 | 01/13/00
01/15/00 | 01/15/00 | 01/15/00
01/15/00 | 01/15/00 | 01/15/00
01/15/00 | 01/15/00 | 01/15/00
01/16/00 | 01/16/00 | 01/16/00
01/19/00 | 01/19/00 | 01/19/00
01/20/00 | 01/20/00 | 01/20/00
01/20/00 | 01/20/00 | 01/20/00
01/27/00 | 01/27/00 | 01/27/00
01/27/00 | 01/27/00 | 01/27/00
01/28/00 | 01/28/00 | 01/28/00
01/30/00 | 01/30/00 | 01/30/00
02/01/00 | 02/01/00 | 02/01/00
02/02/00 | 02/02/00 | 02/02/00
02/03/00 | 02/03/00 | 02/03/00
02/04/00 | 02/04/00 | 02/04/00
02/05/00 | 02/05/00 | 02/05/00
02/06/00 | 02/06/00 | 02/06/00
02/07/00 | 02/07/00 | 02/07/00
02/07/00 | 02/07/00 | 02/08/00

1st Phase

05/08/00 | 05/08/00 | 05/08/00
05/09/00 | 05/09/00 | 05/09/00
05/10/00 | 05/10/00 | 05/10/00
05/11/00 } 05/11/00 | 05/11/00
05/12/00 | 05/12/00 | 05/12/00
05/13/00 | 05/13/00 | 05/13/00
05/15/00 | 05/15/00 | 05/15/00
05/02/00 | 05/02/00 | 05/02/00
05/04/00 | 05/04/00 | 05/04/00
05/05/00 | 05/05/00 | 05/05/00
05/06/00 | 05/06/00 | 05/06/00
05/07/00 | 05/07/00 | 05/07/00

Total Cubic Yards = 5000
Total Cubic Meters = 3823

2nd Phase

Monitoring Cruise at the Morris Cove Borrow Pit

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Location of the Morris Cove borrow pit, central disposal point (MCDA buoy),

and Morris Cove Reference Area

Figure 1-1.

Monitoring Cruise at the Morris Cove Borrow Pit

4
2.0 METHODS

Field operations were conducted over the Morris Cove borrow pit area aboard the
M/V Beavertail on September 28, 2000 and October 2, 2000. Remote Ecological
Monitoring of the Seafloor (REMOTS®) sediment-profile photography was used in
conjunction with side-scan sonar, single beam bathymetry, and towed video to evaluate
benthic conditions within and adjacent to the borrow pit. Sediment profile images also were
obtained at a reference area located approximately 800 m to the west of the disposal buoy to
provide a comparison between ambient conditions and those existing within the borrow pit
(Figure 1-1).

Navigation

Differentially-corrected Global Positioning System (DGPS) data in conjunction with
Coastal Oceanographic’s HYPACK® navigation and survey software were used to provide
real-time navigation to an accuracy of +3 m. A Trimble 4000 RSi GPS receiver was used to
obtain raw satellite data and provide vessel position information in the horizontal control of
North American Datum of 1983 (NAD 83). The GPS receiver was interfaced with a Trimble
NavBeacon XL differential receiver to improve overall accuracy of the satellite data to the
necessary tolerances. The U.S. Coast Guard differential beacon broadcasting from Moriches,
NY (293 kHz) was utilized for real-time satellite corrections.

The DGPS data were ported to HYPACK® data acquisition software for position
logging and helm display. Throughout the survey, individual stations and survey lanes were
selected and displayed in order to position the survey vessel at the correct geographic
location. All point sampling (REMOTS®) positions were logged with a time stamp in
Universal Time Coordinate (UTC) and a text identifier to facilitate Quality Control (QC) and
rapid input into a Geographic Information System (GIS) database. Position information was
logged continuously during the acquisition of survey lane data (side-scan sonar, bathymetry
profiles, and towed video footage).

Side-scan Sonar

A three-lane side-scan sonar survey was conducted over the Morris Cove borrow pit
to aid in defining the edges of the bottom feature, as well as provide additional information
pertaining to the distribution of dredged material. Side-scan sonar data was collected using a
Marine Sonic Technology PC Side-scan System operating at a frequency of 300 kHz. Three
longitudinal transects were completed over the burrow pit, with lane spacing and sonar range
controlled to maximize resolution and aerial coverage (Figure 2-1). After collection, the
side-scan data were used to develop a mosaic of the survey area.

Monitoring Cruise at the Morris Cove Borrow Pit

MORRIS COVE

Target Sidescan Lanes

wa -e ey!
“TES Forbes Blu
"a% ey

180 Meters

Figure 2-1. Longitudinal survey lines occupied over the Morris Cove borrow pit for
collection of side-scan sonar data

Monitoring Cruise at the Morris Cove Borrow Pit

REMOTS® Sediment-Profile Imaging

REMOTS® sediment profile imaging is a benthic sampling technique in which a
specialized camera is used to obtain undisturbed, vertical cross-section photographs (in situ
profiles) of the upper 15 to 20 cm of the seafloor. This is a reconnaissance survey technique
used for rapid collection, interpretation and mapping of data on physical and biological
seafloor characteristics; measurements obtained from sediment-profile images can be used to
characterize sediment types, evaluate benthic habitat quality, map disturbance gradients and
follow ecosystem recovery after disturbance abatement.

The REMOTS® hardware consists of a wedge-shaped optical prism having a standard
35-mm camera mounted horizontally above in a watertight housing. The prism resembles an
inverted periscope, with a clear Plexiglas window measuring 15 cm wide and 20 cm high and
an internal mirror mounted at a 45° angle to reflect the image in the window up to the camera
(Figure 2-2). To equalize pressure, the prism is filled with water, and light is provided by an
internal strobe. The prism sits inside a stainless steel external frame, and the entire assembly
is lowered to the seafloor using a standard winch mounted aboard the survey vessel. Upon
contact with the bottom, the prism descends slowly into the seafloor, cutting a vertical cross-
section profile of the upper 15 to 20 cm of sediment, and a photograph is taken of the
sediment in contact with the window. The resulting 35-mm slides (images) showing
relatively undisturbed sediment profiles are then analyzed for a standard suite of measured
parameters (Rhoads and Germano 1982; 1986).

Computer-aided analysis of each REMOTS® sediment profile image yielded a suite of
measurements. The standard measured parameters are sediment grain size major mode
(expressed in phi units), benthic habitat classification, camera prism penetration depth (an
indirect measure of sediment bearing capacity/density), depth of the apparent redox potential
discontinuity (RPD), infaunal successional stage, and Organism-Sediment Index (a summary
parameter reflecting the overall benthic habitat quality).

A total of 22 REMOTS® sediment profile photography stations were established over
the Morris Cove borrow pit to evaluate the distribution and thickness of dredged material
layers and to assess benthic recolonization. The stations were arranged in a radial pattern
centered at the MCDA disposal buoy position and spaced at 25, 50, 100 and 150 meter
intervals from the buoy (Figure 2-3; Table 2-1). In addition, a five-station REMOTS® grid
was established over the nearby reference area located in New Haven Harbor approximately
800 m to the west of the borrow pit (MC REF; 41° 15.615” N, 72° 54.553” W; see Figure 1-
1). One station was established over the center reference point, while four additional
stations were randomly distributed within a 75-meter radius. At both the borrow pit and
reference area REMOTS® stations, the sediment profile camera was lowered at least three
times in an attempt to obtain three replicate images suitable for subsequent analysis.

Monitoring Cruise at the Morris Cove Borrow Pit

Table 2-1
Morris Cove Borrow Pit REMOTS® Sediment-Profile Photography Stations

[Area [Station | Latitude | _—_Longitude_—
N
N
N
N

[Ar eer Nees ia

MORRIS
COVE

41° 15.644" N
72° 53.975° W

NAD 83

150S 41° 15.563 72° 53.975° W
4 72° 54.082° W

41° 15.587" N 72° 54.051" W
1° 15.587" N 72° 53.899" W

Reference Area

41° 15.629° N
72° 54.575° W

Monitoring Cruise at the Morris Cove Borrow Pit

LIFTING BAR
END CAP
(HOUSING FOR INNER FRAME
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> Sediment-Water Interface
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OF SEDIMENT PROFILE

2.IMAGE REFLECTS OFF 45°

1. FACEPLATE <— MIRROR
or "WINDOW"
OF BRISM Beans
URFACE TOB
PHOTOGRAPHED DISTILLED WATER INSIDE PRISM

Figure 2-2. Schematic diagram of a Benthos Inc. Model 3731 REMOTS® sediment-
profile camera and sequence of operation on deployment

Monitoring Cruise at the Morris Cove Borrow Pit

MORRIS COVE

REMOTS Target Stations

toe

150n
i en 150ne

ia a A
|
F
Leyte
100ne *,
50n *

255W se

j A 425ne :
sow me A50e F

100sw “50s 100se *
"36 °° 7
Ad
A . =
150sw 150se

A Target REMOTS Stations

Figure 2-3. REMOTS® Sediment-Profile Photography Stations established over the
Morris Cove borrow pit

Monitoring Cruise at the Morris Cove Borrow Pit

However, under- or over-penetration of the camera prism into the sediment prevented
analysis of all three replicates at a subset of the stations.

Towed Video Sled

A towed video sled operated by CR Environmental, Inc. was used to conduct a
benthic video survey over the Morris Cove borrow pit. A high-resolution 8 mm video
camera, contained within a specialized pressure housing, was mounted on an aluminum tow
sled. The sled was lowered to the seafloor by a mechanical cable and pulled along a series of
predetermined transect lines by the survey vessel. Video was recorded on tape by the video
camera and simultaneously transferred to the survey vessel via coaxial cable. A topside
Super VHS video recording system recorded the images captured by the video camera and
provided a time stamp for correlation with navigation data.

Three longitudinal and four transverse transects were occupied in an effort to assess
the distribution of dredged material in the Morris Cove borrow pit. Furthermore, the video
was used to characterize the composition of ambient sediment and macrofauna in the pit and
surrounding area (Figure 2-4). The position of the tow sled, based on cable layback, was
logged continuously by the HYPACK® navigation system during the survey operation.

Bathymetric Data Collection and Processing

In addition to displaying vessel position, HYPACK® was interfaced with an Odom
Hydrotrac Fathometer for the collection of depth profiles during both the side-scan sonar and
towed video surveys. The fathometer was equipped with a narrow beam (3°), 208 kHz
transducer to obtain depth soundings to a resolution of 1 cm. Approximately 10 measured
depth values were collected, adjusted for transducer depth (draft), and transmitted to
HYPACK® at a frequency of 1 Hz. The fathometer data recorded by HYPACK® were
averaged, merged with time and position information, and written to a series of navigation
log files at a frequency of 2 Hz. At the conclusion of survey, raw depth soundings were
plotted over the survey lines to re-create vessel track and verify data quality.

The bathymetric data were later processed and analyzed using the HYPACK® single-
beam hydrographic data processing module. Raw bathymetric data files were standardized
to the vertical datum of Mean Lower Low Water (MLLW) using National Oceanographic
and Atmospheric Administration (NOAA) observed tides. Observed tidal data were obtained
through NOAA’s Ocean and Lake Levels Division’s (OLLD) National Water Level
Observation Network. The NOAA 6-minute tide data for 28 September 2000 were
downloaded from http://co-ops.nos.noaa.gov from station (8465705) in New Haven Harbor
and used to formulate tidal height correctors.

Monitoring Cruise at the Morris Cove Borrow Pit

MORRIS COVE

Towed Video Lanes
eal 7.) yy Es eee ee
~~

40 80 120 Meters

Figure 2-4. Track lines for longitudinal transects and transverse transects occupied with
the video towfish.

Monitoring Cruise at the Morris Cove Borrow Pit

The bathymetric data were used to examine bottom topography and correlate
sediment composition information to relative depth within the cell. Precision sound velocity
measurements were not collected during the Morris Cove borrow pit survey. However, an
appropriate value of 1500 m:s" was set in the fathometer for the shallow water survey to
provide acceptable depth data. As a result, a small offset (~20 cm) may exist between the
depth reported in the profile data and the actual water level over the survey area.

Monitoring Cruise at the Morris Cove Borrow Pit

13
3.0 RESULTS
3.1 Side-scan Sonar

The side-scan sonar data were used to create an acoustic map of the seafloor
surrounding the borrow pit and potentially differentiate between ambient sediment and
dredged material placed within the pit. Three lanes of swath data were overlaid to create a
mosaic of the survey area (Figure 3-1). Data collection was curtailed somewhat by shallow
water to the east and an active mooring field in the southern portion of the borrow pit.

The western and northeastern margins of the borrow pit provided a strong sonar
return to the transducer (represented by a thick, dark line) and were readily apparent in the
mosaic (Figure 3-1). Soft sediment (weaker return) appears to have accumulated within both
the northern and southern portions of the borrow pit. Approximately 14,200 m3 of sediment
dredged from the USCG basin were deposited in the southern portion of the pit. Given the
relatively small volume of dredged material disposed and position of the disposal point
(southern portion), most of the fine-grained material detected within the confines of the pit is
likely the result of natural deposition. This fine-grained material could be emanating from
the Mill and Quinnipiac Rivers, advected from other areas of New Haven Harbor, or the
product of multiple sources. The side-scan image shows a gradual strengthening of signal in
close proximity to the margins of the pit, suggesting a coarsening of the sediments, relative
to the center. This change in texture is probably related to an increase in the sand or shell
content of the sediments located near the walls of the borrow pit.

Slight differences in surface texture detected in close proximity to the MCDA buoy
position, relative to the remainder of the sediments in the pit, provide subtle distinctions
between the recently deposited dredged material and the ambient sediments (Figure 3-2).
Multiple bottom features with vertical relief and increased surface roughness were detected
within a 50 m radius of the central disposal point. The larger bottom features, approximately
30 m in diameter, were concentrated to the east of the MCDA disposal buoy. Based on their
position relative to the disposal buoy and size, these features are attributed to dredged
material deposition.

3.2 REMOTS?® Sediment-Profile Imaging
The complete set of REMOTS® image analysis results for both the borrow pit and

reference area stations is presented in Appendix B; these results are summarized in Tables 3-
1 and 3-2.

Monitoring Cruise at the Morris Cove Borrow Pit

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Sidescan Mosaic with Projected Borrow Pit

Northeastern
Margin

Borrow Pit

Area of ‘Sy : ’ Borrow Pit not
Concentrated ot el ee Covered by Sidescan

Analysis

Shallow Area | Shallow

Western
Margin

Mooring Field

60 120 Meters

Figure 3-1. Side-scan sonar mosaic of the three lanes occupied over the Morris Cove
borrow pit

Monitoring Cruise at the Morris Cove Borrow Pit

MORRIS COVE

Area of Concentrated Analysis

100 Meters
—— es ees

Figure 3-2. Side-scan sonar image displaying several acoustically detectable bottom
features within the Morris Cove borrow pit in close proximity to the MCDA
buoy position

Monitoring Cruise at the Morris Cove Borrow Pit

18
3.2.1 Dredged Material Distribution and Physical Sediment Characteristics

Dredged material was detected in the REMOTS® images at 15 of 22 borrow pit
stations (Table 3-1; Figure 3-3). The dredged material layer extended from the sediment
surface to below the imaging depth of the REMOTS® camera at all of these stations (i.e.,
dredged material greater than penetration, denoted by a “greater than” sign in Table 3-1 and
Figure 3-3). Surface sediments considered to be ambient bottom (i.e., unaffected by
dredged material disposal) were observed in the replicate images at Stations 1OONW, 150E,
150SW, 150W, and 150WN located outside or on the presumed edges of the pit (Table 3-1;
Figure 3-3). At Stations 15ONE and 150SE, it could not be clearly determined from the
images whether the material present was dredged material or ambient sediment (INDET =
indeterminate in Table 3-1 and Figure 3-3).

The dredged material comprising the surface sediment within the borrow pit was fine-
grained, composed mainly of sandy silt having a grain size major mode of >4 phi (Table 3-1;
Figure 3-4). At Station 150NE, a hard bottom prevented sufficient penetration of the
sediment profile camera. Replicate-averaged camera penetration depths for the borrow pit
stations ranged from 3.2 cm at Station 150E to 20.8 cm at Station 150SE, with an overall
average of 13.2 cm (Table 3-1). The majority of the penetration depth values were greater
than 10 cm, suggesting the dredged material within the pit was relatively soft. As previously
indicated, the soft nature of the sediment caused the replicate images at some stations to be
overpenetrated, obscuring the sediment-water interface and preventing the measurement of
key parameters (e.g., RPD, successional status, OSI, and boundary roughness).

The average boundary roughness value for the borrow pit stations was 2.33 cm,
indicating a moderate amount of small-scale surface relief (Table 3-1). The irregular and/or
sloping small-scale topography observed at many stations was deemed to be physical in
nature, due to the presence of cohesive clay clumps resulting from the dredging and
subsequent disposal operations (Figure 3-4). There was no obvious spatial pattern in the
boundary roughness values across the surveyed area. A single occurrence of biogenic
surface roughness was due to the presence of a dense mat of tubicolous amphipods
(Ampelisca sp; see Figure 3-4) at station 25NE. Shells and shell hash were observed at the
sediment surface at several stations.

Sediments at the reference area stations were similar to those within the borrow pit in
being predominantly fine-grained (major modal grain size of >4; Table 3-2 and Figure 3-5).
Dredged material was not observed in any of the images at the reference area stations. Mean
camera penetration depths ranged from 10.76 cm at Station REF4 to 14.06 cm at Station
REF1, with an overall average of 13 cm (Table 3-2). This is moderately deep penetration,
comparable to that at the borrow pit stations, which is considered typical for the soft, fine-
grained ambient sediment present at the reference areas.

Monitoring Cruise at the Morris Cove Borrow Pit

Ug)

MORRIS COVE

Apparent Dredged Material Thickness (cm)

>16.02
450N

>14.87. >14.971
A25NW “A25NE

>12.12 >18.62

450W 4CTR 450E
>10.30 >13.66
a25SW 425SE

29.93
450S

Figure 3-3. Map showing the average thickness of the dredged material layer
observed in replicate sediment profile images at each station. A “greater than”
sign indicates that the dredged material layer extended below the imaging
depth of the sediment profile camera.

Monitoring Cruise at the Morris Cove Borrow Pit

Figure 3-4. REMOTS® image from station 100SW within the Morris Cove borrow pit,
showing a layer of fine-grained dredged material extending from the sediment-
water interface to below the imaging depth of the camera (i.e., dredged
material greater than penetration). A clump of cohesive clay measuring 7 cm
in diameter is visible on the sediment surface, resulting in increased small-
scale boundary roughness. Numerous Stage I polychaete tubes protrude from
the clay clump, and a dense Ampeliscid amphipod tube mat (Stage II) is
visible on the left side of image.

Monitoring Cruise at the Morris Cove Borrow Pit

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The average small-scale surface boundary roughness for the reference area stations
(3.5 cm) was higher than that observed at the stations within the borrow pit (2.33 cm). The
reference stations are located in relatively shallow water, where the bottom may be affected
by the scouring action of waves and currents during high-wind events or by fishing (oyster
dredging) activity. The increased boundary roughness, presence of a surface shell lag
deposit, and shallow RPD depths observed at several of the reference stations may reflect
such periodic physical disturbance (Figure 3-5). However, it is notable that similar evidence
of physical disturbance was not observed at the borrow pit stations.

3.2.2 Biological Conditions and Benthic Recolonization

Three parameters can be used to assess the benthic recolonization rate and overall
health of the benthic environment within the borrow pit relative to the reference area:
apparent Redox Potential Discontinuity (RPD) depth, infaunal successional status, and the
Organism Sediment Index (OSI).

The redox potential discontinuity (RPD) measured in each image provides an estimate
of the apparent depth of oxygen penetration into the surface sediment. The replicate-
averaged apparent RPD measurements for the borrow area stations ranged between relatively
high values of 6.33 cm and 4.55 cm at Stations 150S and 25NW, respectively, to a low value
of 0.90 cm at Station L1OONW (Table 3-1; Figure 3-6). The overall average RPD value of
3.04 cm is considered indicative of relatively well-aerated surface sediments within the
borrow pit. None of the replicate images obtained within the borrow pit showed any
evidence of low dissolved oxygen conditions or visible redox rebounds. However, methane
gas bubbles were observed within the sediment column in the images obtained at Stations
100NE, 25NW, and 100SE (Table 3-1). The presence of methane suggests that the dredged
material at these stations contains a relatively high inventory of organic matter that is being
decomposed under anaerobic conditions at depth. It is notable, however, that the dredged
material at the sediment surface at these and other stations within the borrow pit appeared
well oxygenated.

The overall average RPD value for the reference area stations (1.66 cm) was
considerably lower than the borrow pit station average of 3.04 cm (Table 3-2). Replicate
images at Stations REF5 and REF4 had extremely shallow RPD depths of 0.42 cm and 0.52
cm, respectively, possibly related to physical disturbance of the sediment surface (Figure 3-
5). There was no indication of low dissolved oxygen conditions, methane, or visible redox
rebounds at the reference area stations.

As expected for a recent dredged material deposit, the successional stage
recolonization status of the Morris Cove borrow pit included principally Stage I pioneering

Monitoring Cruise at the Morris Cove Borrow Pit

MORRIS COVE

RPD and OSI Values

D7 & 75
A25SW 425SE
5 5

3.93
450S
5

120 Meters

Figure 3-6. Map showing average RPD and OSI values at each borrow pit station.

Monitoring Cruise at the Morris Cove Borrow Pit

MORRIS COVE

Successional Stage Present

UU
“ 150NW

|
4 50N

I III
4 25NW 425NE

LU, I
torr £50E

| |
a25SW 4 25SE

AIA |
4 100SW 4100SE

UU
4 150S

80 Meters

Figure 3-7. Map showing infaunal successional stages present at each borrow pit station.

Monitoring Cruise at the Morris Cove Borrow Pit

Figure 3-8. REMOTS® image showing small, tubicolous, opportunistic polychaetes
(Stage I) present at the surface of fine-grained dredged material at station

100SW within the borrow pit.

Monitoring Cruise at the Morris Cove Borrow Pit

polychaetes present at the sediment surface (Figures 3-7 and 3-8; Table 3-1). Tube-dwelling
amphipods (Ampelisca sp), representative of Stage II, were observed at 7 of the 22 stations
(Figures 3-7 and 3-9). Stage II activity, evidenced by active feeding voids produced by
head-down, deposit-feeding infauna, was predominately noted in the subsurface at Stations
100NE, 100SW, 15ONW, 1508S, and 50E (Figures 3-7 and 3-9). Overall, the presence of a
diverse mixture of Stages I, I and II organisms at the stations within the borrow pit indicate
that benthic recolonization of this area was occurring as expected at the time of the
September 2000 survey.

Stage I successional status dominated the reference areas, with only a single
occurrence of Stage III activity marked by active feeding voids in one replicate image at
Station REF2 (Table 3-2). Dense tube-building Stage I polychaetes, as well as a fecal
mound, were noted in one of the replicate images at station REF2. The dominance of Stage I
organisms and the notable scarcity of Stage Ill at the reference area stations may again be
due to periodic physical disturbance experienced in this shallow area.

Median OSI values for the borrow pit stations ranged from +3 at Stations 1OONW,
150SW, and 100SE to +11 at Station 100NE (Table 3-1 and Figure 3-6). This range of values
suggests variable benthic habitat quality across the area, ranging from moderately disturbed
(OSI values of +3 to +6) to healthy or undisturbed (OSI values >+6).

Values at the lower end of the scale (+3 to +6) reflect somewhat shallow RPD depths,
an absence of Stage I] and II infauna, and/or the presence of methane in the sediment.
Values greater than +6 generally reflect well-developed RPD depths and the presence of both
Stage II and III recolonizing organisms. Such spatial variability in conditions is typical for
an area, like the borrow pit, which had experienced significant physical disturbance related to
dredged material placement as recently as 5 months prior to the September 2000 survey.
Benthic organisms appeared to have recolonized some areas of the dredged material deposit
to a more advanced degree (i.e., Stages II and I) than others (dominated by Stage I only).
This variability in the distribution of recolonizing benthos is normal so soon after the initial
disturbance, and it is anticipated that organisms representing more advanced successional
stages will become more widely distributed over time. In the absence of additional dredged
material disposal, increases in the density of Stage Il and Ill organisms should be reflected in
higher OSI values at the borrow pit stations in the future.

Shallow mean RPD depths together with only Stage I activity at the Morris Cove
reference areas served to diminish the median OSI values to a range of +2 to +7
(Table 3-2). The exceptionally low OSI values for Stations REF4 and REF5 reflect very
shallow mean RPD depths and the lack of Stage IJ or II individuals (Figure 3-5). The
northernmost reference areas (REF2 and REF3) appeared to display somewhat healthier
benthic conditions than the surrounding stations with deeper mean RPD depths, Stage II

Monitoring Cruise at the Morris Cove Borrow Pit

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individuals, and elevated OSI values. Overall, the lower average OSI value for the reference
area stations (+3.8) compared to the borrow pit (+5.6) suggests that the ambient bottom in
Morris Cove was more highly disturbed at the time of the survey.

3.3 Towed Video Survey

The towed video survey was conducted to document the apparent composition of the
surface sediments within the borrow pit. A series of seven transects (three longitudinal and
four transverse) were occupied in and around the Morris Cove borrow pit. Individual
transects are displayed in Figures 3-10 through 3-14 with both an aerial perspective and a
profile view presented. The corrected bathymetric profiles were used to compare depth and
slope to apparent surface sediment composition. A summary graphic displaying the
composite results of all seven transects is presented in Figure 3-15.

3.3.1 Sediment Composition

In general, fine sand, silt, and shell fragments were detected in patches throughout the
entire borrow pit. As expected, a correlation between bottom slope and sediment
composition was observed, with silt accumulating in the deeper, low relief areas of seafloor
and fine, silty sand/shell fragments detected along the walls of the borrow pit. Distinctions
between ambient sediment and recently deposited dredged material were difficult to detect
on the surface due to the age of the deposit, similar lithology (fine sand and silt), and the high
optical reflectance of the well-oxygenated surface layer.

Transect A was a longitudinal pass within the boundaries of the borrow pit,
concentrating on the western margin of the bottom feature (Figure 3-10). The starting point
for this line was placed approximately 450 m north of the MCDA buoy position. Soft
material was observed for the majority of this transect with silty sand and shell fragments
observed as the video sled encountered the sloping walls of the pit. Silt was predominant in
areas of low relief and tended to be found at water depths below 5 m. A few patches of
pebble and cobble sized rock were also observed on the bottom, as the video sled was towed
south and east through the pit. The seafloor within a 30 m radius of the MCDA buoy
position was characterized as a silty sand, but showed no obvious differences from the
surface sediments in the northern portion of the borrow pit.

Transect B represents the first transverse route occupied over the Morris Cove borrow
pit. The video sled passed approximately 60 m southeast of the disposal buoy position
(Figure 3-11). Fine, silty sand was observed in the shallow areas on either end of the
transect, and patches of silt were found at depth. Once again, a correlation with bottom slope
was detected as the margins of the pit were composed of fine sand or fine sand with shell.

Monitoring Cruise at the Morris Cove Borrow Pit

MORRIS COVE

Towed Video Transect A

Vidso
*% macrophytc algae
@ rock

Meters

4570250 4570200 4570150 4570100 4570050 4570000 4569950 4569900 4569850 4569800 4569750
UTM Zone 18 meters

Figure 3-10. Aerial perspective and profile view of surface sediment characterization data
obtained for Transect A displaying distribution of fine sand (yellow), silt
(magenta), shell lag (tan), rock (black) and macrophytic algae (gray).

Monitoring Cruise at the Morris Cove Borrow Pit

MORRIS COVE

Towed Video Transect B

Video
« Macrophytic algae
rock

Meters

676100

675850 675900 675950 676000 676050

675800
UTM Zone 18 meters

V.E.=6.5

Figure 3-11. Aerial perspective and profile view of surface sediment characterization data
obtained for Transect B displaying distribution of fine sand (yellow), silt
(magenta), shell lag (tan), rock (black) and macrophytic algae (gray).

Monitoring Cruise at the Morris Cove Borrow Pit

MORRIS COVE

Towed Video Transect C

ideo

‘a macrophytic algae sand

@ rock e shell lag
sit

Meters

676100 676150

675900 675950 676000
UTM Zone 18 meters V.E.=8

Figure 3-12. Aerial perspective and profile view of surface sediment characterization data
obtained for Transect C displaying distribution of fine sand (yellow), silt
(magenta), shell lag (tan), rock (black) and macrophytic algae (gray).

Monitoring Cruise at the Morris Cove Borrow Pit

MORRIS COVE

Towed Video Transect D

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OOWAN OD OAA WN - OO

4570200 4570150 4570100

4570050 4570000 4569950

4569900 4569850
UTM Zone 18 meters

V.E.=6.8

Figure 3-13. Aerial perspective and profile view of surface sediment characterization data

obtained for Transect D displaying distribution of fine sand (yellow), silt
(magenta), shell lag (tan), rock (black) and macrophytic algae (gray).

Monitoring Cruise at the Morris Cove Borrow Pit

MORRIS COVE

Towed Video Transect F

675900 675950 676000 676050 676100 676150
UTM Zone 18 meters V.E.=8.1

Figure 3-14. Aerial perspective and profile view of surface sediment characterization data
obtained for Transect F displaying distribution of fine sand (yellow), silt
(magenta), shell lag (tan), and macrophytic algae (gray).

Monitoring Cruise at the Morris Cove Borrow Pit

MORRIS COVE

Towed Video

Video 30 O 30 60 90 120 Meters
a ee |

Figure 3-15. Aerial perspective of towed video Transects A through G showing agreement
in sediment classification between overlapping and closely spaced tracklines.

Monitoring Cruise at the Morris Cove Borrow Pit

Silt tended to accumulate in the deeper (>5 m), low relief areas in the pit. A few small
patches of rock were noted along this line, one of which was found on a bathymetric feature
near the mid-point of the transect.

The depth profile for Transect B displayed a bottom feature with vertical relief of
2.5 m and a diameter of 50 m near the center of the pit (Figure 3-11). The margins of this
feature were composed of fine sand and the sediments over the relatively flat top of the
mound were classified as silt. Based on its location relative to the disposal buoy (southeast),
this feature is likely the product of recent dredged material disposal activity.

Transect C also represents a transverse pass over the borrow pit. Once again, small
patches of silt, fine silty sand, fine sand with shell, and a limited amount of pebble and
cobble sized rocks were observed within the video record (Figure 3-12). The video sled
passed 20 m northeast of the disposal buoy position as it was towed east-southeast across the
borrow pit. Similar to the interpretations of Transect A, the surface sediments in close
proximity to the MCDA buoy position were characterized as fine, silty sand. No obvious
visual distinctions were observed between ambient sediment and the surface of the recent
dredged material deposit. The depth profile for Transect C showed limited vertical relief to
the west of the buoy position before the bottom gradually sloped to the deepest portion of the
pit (water depth of 10 m). Silt was the major constituent of the sediments within the deepest
portion of the pit.

Transect D was the second longitudinal pass made over the Morris Cove borrow pit,
and designed to document the composition of sediment along the eastern margin of the pit.
Due to unreliable navigation data from the DGPS unit during the occupation of Transect D,
the position of the video sled was approximated for the majority of this line. The
bathymetric data were used in conjunction with the NOAA chart pictured in Figure 3-13 to
place the line along the eastern margin of the borrow pit. Overall, a similar lithology and
distribution of sediments were observed, relative to other transects. Fine sand with varying
shell content was noted in areas near the walls of the pit and silt was found over the flat areas
within the pit. The video data collected in the southern portion of the borrow pit suggested
that seafloor composition east of the buoy position is quite patchy.

Transect F was a third transverse pass made over the borrow pit and sampled an area
approximately 25 m southeast of the MCDA buoy position. In general, Transect F displayed
similar combinations in bottom composition relative to Transects C and B with silt, shell lag,
and sand represented in the video images (Figure 3-14). A strong bathymetric feature east of
the MDCA buoy with a minimum depth of 5.5 m was detected in the depth profile.

However, due to the lack of baseline bathymetric data, it is difficult to discern whether this
feature is the direct result of dredged material deposition or simply enhanced by the
placement of 14,000 m3 of sediment.

Monitoring Cruise at the Morris Cove Borrow Pit

The depth soundings collected during this video transect indicated the western side of
the borrow pit sloped down into a small basin composed primarily of silt. This flat region
displayed a depth of 9 m before depths gradually decreased in association with the presence
of the dredged material feature. The depth values within the borrow pit as indicated on the
NOAA chart for New Haven Harbor suggest the water column along Transect F was deeper
at one time (Figure 3-14). Extrapolating from the NOAA soundings, a potential area of
recent dredged material accumulation was identified in the basin and over the apex of a
shallow area (originally 24 ft). Based on the reported disposal volume, narrow configuration
of the borrow pit, and relatively shallow water depths, a dredged material deposit ranging in
thickness from 0.5 to 1.5 m is possible.

Two additional transects (one longitudinal and one transverse) were occupied and
results overlaid on the data from Transects A, B, C, D, and F (Figure 3-15). In general,
strong agreement was observed in the classification of sediment along the margins and
within the northern portion of the borrow pit. The surface sediment distribution within the
southern portion of the borrow pit appeared more heterogeneous as differences in sediment
classification were noted on several overlapping, or closely spaced tracklines (i.e. Transects
A and F). This disagreement is likely the result of the chaotic nature of the dredged material
and the many small patches of fine sand, silt, and shell on the surface of the deposit.

3.3.2 Benthic Macrofauna

The macrofauna encountered during the towed video survey included horseshoe crabs
(Limulus polyphemus), sea stars (Asterias sp.), Common Oysters (Crassostrea virginica), as
well as active mussel beds, and various finfish. The bivalves and sea stars were found
inhabiting the walls of the pit, as well as concentrated in the areas outside the pit. The
horseshoe crabs and finfish were found foraging in the silt deposits within the borrow pit.
Macrophytic algae (mainly Ulva) were detected in small clumps along several survey lines
(Figure 3-15). However, there was no discernable pattern in spatial distribution.

Monitoring Cruise at the Morris Cove Borrow Pit

4.0

CONCLUSIONS

The findings of this survey indicate that the use of the Morris Cove borrow pit as an

alternate dredged material disposal site during the 1999-2000 disposal season was successful.

Controlled disposal of small barge loads of dredged material facilitated the
development of a small-scale sediment deposit within the confines of the pit.

REMOTS® photographs indicated the presence of sediments displaying
characteristics of dredged material in close proximity to the MCDA buoy position and
extending out 100 m to 150 m from the central disposal point.

Side-scan sonar and towed video data suggest the impacts associated with the
deposition of new material (small-scale bottom features and heterogeneous surface
sediment composition) were contained within the southern portion of the borrow pit.

At five months post-disposal, benthic recolonization of the new sediment deposit
appears to be progressing as expected.

Many of the REMOTS® stations within the borrow pit displayed moderate to deep
RPD depths and advanced successional status (Stage II and/or III organisms present at
8 of the 22 stations occupied).

Due to the protected nature of the borrow pit and the recent input of organically
enriched sediment, benthic habitat conditions exceeded those observed at the New
Haven Harbor reference area.

Monitoring Cruise at the Morris Cove Borrow Pit

38
5.0 REFERENCES

Rhoads, D. C.; Germano, J. D. 1982. Characterization of organism-sediment relations using
sediment-profile imaging: An effective method of Remote Ecological Monitoring of
the Seafloor (REMOTS® System). Mar. Ecol. Prog. Ser. 8:115-128.

Rhoads, D. C.; Germano, J. D. 1986. Interpreting long-term changes in community structure:
A new protocol. Hydrobiologia 142:291-308.

Monitoring Cruise at the Morris Cove Borrow Pit

INDEX

anaerobic, 22
barge, vi, 1, 37
benthos, vi, 1, 4, 6, 8, 10, 22, 24, 26, 36,
37
ampeliscids, 18, 20, 26
amphipod, 18, 20, 26
bivalve, 36
macro-, 10, 36
mussels, 36
polychaete, vii, 20, 25, 26
bioturbation
feeding void, 26, 27
foraging, 36
boundary roughness, vi, 18, 20, 22
buoy, 1, 3, 6, 13, 17, 28, 35, 36, 37
disposal, vi, 1, 4, 6, 13, 28, 35
currents, vi, 21, 22
density, 6, 26
deposition, vi, 1, 13, 36, 37
disposal site
Central Long Island Sound (CLIS), 1
dissolved oxygen (DO), 22
feeding void, 26, 27
fish
finfish, 36
grain size, 6, 18, 21
habitat, vii, 6, 26, 37
methane, vi, 14, 22, 26
National Oceanic and Atmospheric
Administration (NOAA), 10, 35, 36
recolonization, vi, 1, 6, 22, 26, 37
reference area, vi, vii, 4, 6, 13, 18, 21, 22,
26, 28, 37
reference station, 22

REMOTSS®, 4, 6, 7, 8, 9, 13, 14, 15, 18,
2OW2I 2S S2i5 37, 38, 40
boundary roughness, vi, 18, 20, 22
Organism-Sediment Index (OSD), 6, 14,
IS SH2259235 26028
redox potential discontinuity (RPD), 6,
22
sediment-profile camera, 8
RPD
REMOTS®, redox potential
discontinuity (RPD), 6, 14, 15, 18, 21,

Did, Os Xo, 81)
sediment
clay, 18, 20
cobble, 28, 35
gravel, 1
sand, vi, 1, 13, 18, 28, 29, 30, 31, 32,
33, 35, 36

silt, vi, 18, 28, 29, 30, 31, 32, 33, 35, 36
side-scan sonar, vi, 4, 5, 10, 13, 16, 17, 37
species

dominance, 26
succession

pioneer stage, vii, 22
successional stage, vii, 6, 22, 24, 26
survey

baseline, 36

bathymetry, vi, 4, 10, 12, 28, 35, 36
tide, 10
topography, 12, 18, 21
trace metals

arsenic (As), 12, 18, 22, 28

vanadium (V), 4
waves, vi, 21, 22

Appendix A
Morris Cove Borrow Pit Disposal Logs

2000

Project:

Permit Number:

Buoy
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS
MCDS

Appendix A, Disposal Logs

MORRIS COVE

Channel & Dock Area

199901985

Departure Disposal

1/10/00
1/11/00,
1/12/00
1/13/00
1/13/00
1/13/00
1/15/00
1/15/00
1/15/00
1/16/00
1/19/00
1/20/00
1/20/00,
1/27/00
1/27/00
1/28/00
130/00
2/1/00
2/2/00
2/3/00
2/4/00
2/5/00,
2/6/00
2/7/00
2/7/00,
5/2/00
5/4/00
5/5/00
5/6/00.
5/7/00
5/8/00,
§/9/00
5/10/00
S/L1/00
3/12/00
5/13/00
$/15/00

1/10/00
1/11/00,
1/12/00
1/13/00
1/13/00
1/13/00
1/15/00
1/15/00
1/15/00,
1/16/00
1/19/00,
1/20/00,
1/20/00
1/27/00
1/27/00,
1/28/00
1/30/00
2/1/00
2/2/00,
2/3/00
2/4/00
2/5/00
2/6/00
2/7/00
2/7/00
$/2/00
§/4/00,
5/5/00)
5/6/00.
5/7100
5/8/00
5/9/00
5/10/00
5/11/00
5/12/00
5/13/00
5/15/00

Permittee:

Return
1/10/00
1/11/00
1/12/00
1/13/00
1/13/00
1/13/00
1/15/00
1/15/00
1/15/00,
1/16/00
1/19/00
1/20/00
1/20/00
1/27/00
1/27/00
1/28/00
1/30/00

2/1/00
2/2/00
2/3/00
2/4/00
2/5/00,
2/6/00
2/7/00
2/8/00
§/2/00
5/4/00
5/5/00
5/6/00
5/7/00
5/8/00
5/9/00
5/10/00
5/11/00
5/12/00
5/13/00
5/15/00

U.S. Coast Guard

Latitude Longitude Buoy’s Vector Volume (CY)

41.25983333

41.26071667
41.266
41.26061667
41.26145
41.26045
41.26123333
41.26083333
41.26123333
41.26123333
41.26083333
41.26083333
41.2608
41.26128333
41.26096667
41.26071667
41.26018333
41.26023333
41.26071667
41.26031667
41.261

41 .26067
41.26058
41.26067
41.26067
41.26067
41.2606666
41.26083
41.26067
4+1.26083
41.26083
41.26067

-72.9008333

-72.9012
-72.9003833
-72.90065
-72.9005833
-72.9005 167
-72.8997
-72.9001833
-72.9005833
-72.90065
-72.90065
-72.9005833
-72.9005833
-72.9007833
-72.90045
-72.8999833
-72.90025
-72.9008
-72.9001 167
-72.9005833
-72.90025
-72.9001 167
-72.9001833
-72.89983
-72.89983
-72.89967
-72.89967
-72.89967
-72.89967
-72.89967
-72.89933
-72.89967
-72.8995
-72.89917
-72.89967

Project Total Volume:

Yearly Total Volume:

20"
30°

14,222 CM
14,222 CM

SSW

300
600
600
700,
400
600,
700
800,
400,
650
S00
800
800
800
900
500
400
450,
400
400
450,
400
350)
400
300
300
550
600
400
500,

100

18,600 CY
18,600 CY

Appendix B
Morris Cove Borrow Pit September 2000 REMOTS® Results

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