REPORT DOCUMENTATION PAGE 



form approved 



0MB No. 0704-0188 



Public reporting concern for the collection of information is estimated to average 1 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 



Mavl998 



3. REPORT TYPE AND DATES COVERED 



FINAL REPORT 



4. TITLE AND SUBTITLE 



MONITORING CRUISE AT THE WESTERN LONG ISLAND SOUND DISPOSAL SITE, 

 JULY 1996 



6. AUTHOR(S) 



JOHN T. MORRIS 



5. FUNDING >fUMBERS 



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



Science Applications International Corporation 

 221 Third Street 

 Newport, Rl 02840 



8. PERFORMIGORGANIZATION 

 REPORT NUMBER 



SAIC No. 383 



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



US Army Corps of Engineers-New England District 



696 Virginia Rd 



Concord, MA 01742-2751 



10. SPONSORING/MONITORING 

 AGENCY REPORT NUMBER 



DAMOS Contribution #1 19 



11. SUPPLEMENTARY NOTES 



Available from DAMOS Program Manager, Regulatory Branch 

 USACE-NAE, 696 Virginia Rd, Concord MA 01742-2751 



12a. DISTRIBUTION/AVAILABILITY STATEMENT 



Approved for public release; distribution unlimited 



12b. DISTRIBUTION CODE 



13. ABSTRACT 



A monitoring survey was conducted at the Western Long Island Sound Disposal Site (WLIS) from 10 to 18 July 1996 as part of the Disposal Area Monitoring System 

 (DAMOS) Program. The field efforts were concentrated over the active southwestern quadrant of WLIS and consisted of precision bathymetry and Remote Ecological Monitoring of the Seafloor 

 (REMOTS®). These surveying techniques were used to monitor the development, stability, and benthic recolonization of the disposal mounds formed on the WLIS seafloor from 1992 through 

 1996. 



Currently, a total of eight discrete disposal mounds exist on the WLIS seafloor within an east-west trending trough that extends through the center of the site. The latest survey activity 

 was concentrated over the three most recent dredged material deposits, the WLIS H, WLIS G, and WLIS F mounds, as well as the southern flank of the older WLIS D mound. 



The WLIS H mound is the most recent bottom feamre formed within WLIS. The WDA buoy received approximately 15,300 m' of sands, silts, and clays from 15 April to 29 May 

 1996. The deposition of this material resulted in the formation of a 1.5 m high disposal mound, approximately 230 m in width. REMOTS® sediment-profile photography detected a solid Stage I 

 pioneering polychaete community with some evidence of Stage III activity, as well as deep Redox Potential Discontinuity (RPD) depths over the majority of the H mound. 



An estimated barge volume of 52.500 m' of sediment, originating from coastal New York and Connecticut, was disposed during the 1994-95 disposal season. The resulting dredged 

 material deposit, the WLIS G mound, was found to be 2.5 m high and connected to adjacent disposal mounds (D and F) by a wide apron of dredged material. The infaunal population consists 

 mainly of Stage I individuals with some evidence of Stage III activity. 



The WLIS F mound is the product of modest dredged material deposition at WLIS over a three-year period. The DAMOS disposal buoy WDA was positioned in nearly the same 

 location during the 1991-92, 1992-93, and 1993-94 disposal seasons. The final product of three years of dredged material deposition was a sediment mound with a height of 3.0 m at the apex and 

 an overall width of approximately 250 m. Limited REMOTS® sediment-profile data collected over WLIS F found a healthy benthic environment with deep RPD depths and Stage I and Stage III 

 organisms. 



The WLIS D mound was developed during the 1989-90 disposal season by the deposition of approximately 185,000 m' of material. Annual monitoring effons with REMOTS® 

 sediment-profile photography in 1991 . 1992, and 1993 detected anomalous conditions over the southern flank of the WLIS D mound. Two stations. D200S and D300S, were occupied during the 

 July 1996 survey at WLIS to verity improvement in benthic conditions. 



Station D300S displayed dramatic improvement with a median Organism-Sediment Index (OSI) value of 8.0. attributable to deep RPDs and presence of Stage III individuals. Two of 

 the three replicate photographs collected at D200S determined that a localized problem still exists within the surface sediments. However, this problem could be resolved by developing a new 

 disposal mound southwest of the WLIS G mound center. The new material would cover the southern flank of the D mound and isolate this apparently small patch of problematic surface 

 sediments. 



Although determined to be feasible, subaqueous capping operations have not occurred at WLIS. However, efficient and controlled disposal of large volumes of dredged material could 

 easily be facilitated within the disposal site. The strongly sloping terminal moraine margin present in the southern region of the disposal site could be utilized as a natural ridge for the development 

 of lateral containment cells. 



Historic dredged material disposal activity has led to a broad distribution of dredged material over the western Long Island Sound seafloor. As a result, the detection of dredged 

 material within WLIS reference areas is possible, even though special care is taken at their initial selection The results of the July 1996 REMOTS® sur\'ey over die current WLIS reference areas 

 suggest that the use of 2000W for comparison widi WLIS disposal mounds should be discontinued. The presence of dark, reduced sediments and metliane gas bubbles indicate the surface 

 sediments are not representative of the ambient sediment, free from the effects of anthropogenic activity. 



Upon review of the benthic community assessment data collected at WLIS since 1984. a trend of shallow RPD depths, indications of low DO, and poor benthic habitat can be 

 associated with mid-summer monitonng efforts. The results obtained during the July 1996 and other recent surveys (June 1991, July 1992) suggest the complerion of benthic community assessment 

 operations in early summer, before die development of hypoxia and die deterioration of conditions, yields a more realistic perspective into the year round condition of the benthic environment. 



14. SUBJECT TERMS precision bathymetry, Remote Ecological Monitoring (REMOTS), 

 organism sediment index (OSI), disposal mounds 



15. NUMBER OF PAGE 



16. PRICE CODE 



17. SECURITY CLASSIFICATION OF 

 REPORT Unclassified 



18. SECURITY CLASSIFICATION 

 OF TfflS PAGE 



19. SECURITY CLASSIFICATION 

 OF ABSTRACT 



20. LIMITATION OF 

 ABSTRACT 



