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4. TITLE AND SUBTITLE 



Monitoring Cruise at the Morris Cove Borrow Pit 



6. AUTHOR(S) 



Science Applications International Corporation 



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



Science Applications International Corporation 

 221 Third Street 

 Newport, Rl 02840 



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 



form approved 



OMB No. 



0704-0188 



1. AGENCY USE ONLY (LEAVE BLANK) 



2. REPORT DATE 



June 2001 



3. REPORT TYPE AND DATES COVERED 



FINAL REPORT 



5. FUNDING NUMBERS 



8. PERFORMING 

 ORGANIZATION REPORT 

 NUMBER 



SAICNo. 520 



10. SPONSORING/MONITORING 

 AGENCY REPORT NUMBER 



DAMOS Contribution Number 129 



12a. DISTRIBUTION/AVAILABILITY STATEMENT 



Approved for public release; distribution unlimited 



12b. DISTRIBUTION CODE 



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 compnsing 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 matenal had 

 facihtated 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 

 matenal 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 durmg 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 111) 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 



15. NUMBER OF TEXT PAGES: 38 



16. PRICE CODE 



17. SECURITY CLASSIFICATION OF 

 REPORT Unclassified 



18. SECURITY CLASSIFICATION 

 OF THIS PAGE 



19. SECURITY CLASSIFICATION 

 OF ABSTRACT 



20. LIMITATION OF 

 ABSTRACT 



