Monitoring Cruise at the Morris Cove Borrow Pit

Disposal Area Monitoring System DAMOS

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Woods Hole Oceanographic Institution |

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Ta ee ee lf DISPOSAL AREA MONITORING SYSTEM

Contribution 129 June 2001

US Army Corps of Engineers « New England District

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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 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 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 S300)" YS BASS GIS eg al tp ch nL a Se AR SSUES 13 Sal Side-scanS OMamcces! Vice see ees calle ease tah teaine ta de wecmen sau anassataa sd. namee ease nes 13 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 BB ORR © Ws PUG a caries ee anc saat aed etalon tn eM res EC ck AAI Fe ale edn aM RNC 14

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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 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 m radius 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 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

vi

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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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

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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

6

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 ELECTRONICS)

OUTER FRAME

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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

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7

255W se

j A 425ne : sow me A50e F

r

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

10

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

I]

MORRIS COVE

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

LG

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

12

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

17

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

24

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

26

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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28

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

29

MORRIS COVE

Towed Video Transect A

12

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

30

MORRIS COVE

Towed Video Transect B

35

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

31

MORRIS COVE

Towed Video Transect C

lf

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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4570050 4570000 4569950

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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

lf

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

oe

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

35

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

36

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

37

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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