FiMS Te (Me Twi Con+, 47 Monitoring Cruise at the Central Long Island Sound Disposal Site June 1991 Disposal Area Monitoring System DAMOS DA/|M O §$ DISPOSAL AREA MONITORING SYSTEM Contribution 97 October 1995 US Army Corps of Engineers New England Division REPORT DOCUMENTATION PAGE OMB 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, Sulte 1204, Arlington VA 22202-4302 and to the Office of Management and Support, Paperwork Reduction 2. REPORT DATE 8. REPORT TYPE AND DATES COVERED October 1995 Final report 5. FUNDING NUMBERS 4. TITLE AND SUBTITLE Monitoring Cruise at the Centeral Long Island Sound Disposal Site, June 1991 6. AUTHOR(S) M. Baker Wiley & J. Charles . PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Science Applications International Corporation 221 Thrid Street Newport, RI 02840 8. PERFORMING ORGANIZATION REPORT NUMBER SAIC-92/7621&C100 0. SPONSORING/ MONITORING AGENCY REPORT NUMBER DAMOS Contribution Number 97 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) US Amy Corps of Engineers-New England Division 424 Trapelo Road Waltham, MA 02254-9149 11. SUPPLEMENTARY NOTES Available from DAMOS Program Manager, Regulatory Division USACE-NED, 424 Trapelo Road, Waltham, MA 02254-9149 12a. DISTRIBUTION/AVAILABILITY STATEMENT Approved for public release; distribution unlimited 2b. DISTRIBUTION CODE 413. ABSTRACT (MAXIMUM 200 WORDS) Science Applications International Corporation (SAIC) conducted a monitoring survey at the Central Long Island Sound (CLIS) Disposal Site from 18 to 23 JUNE 1991 as part of the DAMOS (Disposal Area Monitoring System) Program. The objectives of the June 1991 field operations were to map the distribution and thickness of the dredged material in the areas that received project materials after the 1990 DAMOS survey (CLIS-90 and CS-90-1) and to evaluate the status of inactive mounds: MQR, NHAV-74, CLIS-88, CLIS-89, CS-1 and FVP. Surveying and monitoring techniques included precision bathymetry, REMOTS sediment-profile photography, CTD and dissolved loxygen information, and sediment grab samples. In September 1990, the CLIS disposal buoy was deployed at 41°9.212'N, 72°53.25'W. Barges released approximately 59,000 m3 of dredged material at this location between September 1990 and May 1991. It was predicted that a new disposal mound would form at this location. During the 1989/1990 disposal season, barges released 8,730 m3 of additional dredged material at CS-90-1 to increase cap hickness. The precision bathymetric survey detected a small, newly formed disposal mound at the CLIS-90 buoy location. The addition of 8,730 m3 of material to the CS-90-1 was detectable in the bathymetric survey as two 20cm thick areas of accumulation. REMOTS sediment-profile photography detected the presence of dredged material at all stations within the survey area. “Fresh” or recent dredged material, identified by sedimentary fabric and shallow apparent RPD (Redox Potential) depths, was several hundred meters away from the active mounds. The limit of the dredged material mound, as mapped acoustically, was within a 100 m radius of the CLIS-90 buoy location. Benthic recolonization was deterimed from analysis of REMOTS photographs obtained at CLIS and at three outlying reference areas. Recolonization predictions from the DAMOS tiered monitoring and management protocol were that the active mounds should be in a Stage | sere while Stage III sere should colonize the inactive mounds: MQR, NHAV-74, CLIS-88, CLIS-89,CS-1, and FVP. The 1991 REMOTS data supported these predictions. Water column profiles of temperature, salinity, sigma-t, and dissolved oxygen were determined on June 18th at the CLIS-90 buoy and three reference areas. The water column at these four sampling stations was stratified with respect to both temperature and salinity. [Dissolved oxygen (DO) concentrations below the pycnocline were 6 to 7 ppm, 2 to 3 ppm lower than near surface values. DO values were similar between the CLIS-90 buoy location and the three reference locations. Sediment samples collected from the CLIS reference areas contained metals in similar low concentrations as measured during previous CLIS surveys. Polyaromactic hydrocarbons (PAH's) were also analyzed to provide a baseline for future sampling. PAH’s were measured at all three reference areas in concentrations generally within ranges present in regional Long Island Sound. 14. SUBJECT TERMS SAIC CLIS DAMOS surveying bathymetry REMOTS disposal mound RPD_ sedimentsamples CTD DO ISJERICEICODE 17. SECURITY CLASSIFICATION OF REPORT 18. SECURITY CLASSIFICATION OF THIS 9. SECURITY CLASSIFICATION OF (20. LIMITATION OF ABSTRACT Unclassified PAGE ABSTRACT MONITORING CRUISE AT THE CENTRAL LONG ISLAND SOUND DISPOSAL SITE JUNE 1991 CONTRIBUTION #97 October 1995 Report No. SAIC 92/7621 &C100 Submitted to: Regulatory Division New England Division U.S. Army Corps of Engineers 424 Trapelo Road Waltham, MA 02254-9149 Prepared by: M. Baker Wiley J. Charles Submitted by; Science Applications International Corporation Admiral's Gate 221 Third Street Newport, RI 02840 (401) 847-4210 US Army Corps of Engineers New England Division a feel Eee TABLE OF CONTENTS Page SM OEBDAB EES aha ts edhe aban bea ae atde Bokesiy 8 ik alte fet ee ated Mobile? ca haenins ced iV NSIMRORSEIG URES Ce ce fe liov'ciis Se Sek, Mea ek ad ot ert Be eM one, Sa TT as AC SUAIN. 5 yell Vv EXE CUI E SU MIMAR Yor (rit OS 1 SATS LEG WS AUP x Sola ent Mice rant OBoc.. 0 Sie eet Vii Ie OM ee INTRODUCTIONS 3250 455 Bea SUG ee at PR ae WE eae, in” he ae 1 Oe Ola VUES OTD Sip facies evar vabeennd ne, Chasen its sch ere a Bsa er an ae ene SG emcee oh RPGR A 5) 2elt.-Bathymetry.and: Navigation 7... 2200080 te Ge Re nae, ee ae 5 22) REMOFS® Sediment-Profile| Photography) 20.23 ee es 5 223, 41 -sediment.samplingzand) Analysis’) 2225.0 fre se rt eet eee oa cen See 7 Zed Grains Size “Analy SiS. sare Gans eich area ae ee a oe 1 Zesno) wotal Organic 1CarbomMen ey a. ssn aes Bee ene ce eons ce 7 2.355 Metal-and/PAHn Analyses. fiir. koeie fees beta ne macel sey ah ae 9 PAE ce SAO UK | OoNC Raia tan re semeetan enya inte AC eALES Ger Ratan i MAGE rms RMR E es 7 glURae ta 9 2.4), ‘CFD and Dissolved'Oxygen'Sampling <1... 22 2 Se ek ee: 10 GROMMEORE SU Soiree tan na sceh Mtr: lines Mas aula re eter cient a Maen ih fet, 2 lake ayo een 11 Sal Bathymethyes, ste ei os Meee ovat Re hea ® Bianca as OS rN OE a 11 3.2 REMOTS® Sediment-Profile Photography .................... 11 372 lee Sediment: Grain: S1Ze4. eae ete ee teat ee hae een 11 3.2151 Actives MOundS:: W5cce heen ale meee ee Uewon demas 11 Seale? Inactive Mounds and Reference Areas ......... 7 3.2.2 Distribution of Dredged Material ..................... 17 3.22 a1 Active: Mounds). sper et sg ee ahem 17, 325222 Inactive Mounds and Reference Areas ......... 17 3.23 BoundarySROughmess, 444i fs nos so, oe ere il 322301 Active Mounds: 3.20. Gc tes snes ee ec ieee 21 3223322 Inactive Mounds and Reference Areas ......... 21 3-2 4a Apparent RED: Depth yicace eco 8 eee eee eel Ron ee cay Sucereeioe 2 3.2.4.1 Active: Mounds) 2 (28o5 Sonus seer ein eee 21 3.2.4.2 Inactive Mounds and Reference Areas ......... 27, Sed so) SUCCESSIONAl Stages ci.) ct eee, to oe pole ey web eiee eee ee ae Di, 312251 Active: Mounds) 30s. ciate se ieee ces as 27 3.2952 Inactive Mounds and Reference Areas ......... 27 322.6), Organism-sediment Indexes ose sc Gane Chee ot Pay) 3.2.6.1 Active(Mounds: .2uinyugen jase legen ue eis reticence 32 3.2.6.2 Inactive Mounds and Reference Areas ......... 32 TABLE OF CONTENTS (cont.) Page 3-3... Sediment, Analysis. 50.0 eterno es een ne nee 32 3,3, 1 ‘Grain Size and Total’Organic:Carbon\) = 3 4 ee 32 33.2) sMetals. eoie a) evan ee Maa ota ie ates prs incr eee ng ee 32 B53. DPAS oe ch 8 ihe i ao anes aay cote ere eyo ce ee em 38 3.4") (ETD) and) Dissolved’ Oxygen) Sampling; 2 eo ee eee 38 ASO EDISCUSSION) cleus. Sal onde eee Sle ee eine eee na a eee 41 4A > Disposal ‘Mound! Topography -\. 252i che eee re) ee gee 41 42~ + CleS:Successionall: Status ics hg hai he ego ee ee ee ett eee eae 43 4°3-.. CIS (Reference Area Chemistry. ayer tae eno ae ate ae 44 4.4- Bottom Water Dissolved Oxygen. Soins oe Semis chee 48 S10 ACONGCIEUSIONS (itso tines aa oN Ry al cee ete etree a eu ney Ee rat eee cia” ae a 50 GOEL REFERENCES iio oi a) Sia ead Tia eh RM al at ie eer illn OR PAE Se ar ae a2 INDEX APPENDIX ul LIST OF TABLES Table 2-1. Table 3-1. Table 3-2. Table 3-3. Table 3-4. Table 4-1. Table 4-2. Table 4-3. Page Summary of Laboratory Analytical Work, Summer 1991 ........... 9 Results of Sediment Grain Size Analyses and Percent Total Organic Carbon (TOC) for CLIS Reference Areas, June 1991 ....... 33 Metals Results (ppm Dry Weight) for Sediments Collected at theyGleISsReferencevAreas) June3199 li eee ee caren eon ee 34 Results of PAH Analyses (ppb Dry Weight) for Sediments Gollectediat the: GEIS -ReferenceyAreas; 1991 = ae eee 39 Dissolved Oxygen Concentrations at Selected Disposal Site and Reference: stations at: CLIS June! 1991s ee eee eee eae 40 Metals Concentrations (ppm Dry Weight) in Sediments Collected at NLON, CLIS, and WLIS in 1986 and 1987 ............ 45 Comparison of NOAA’s NS&T Data with CLIS Reference Areas ..... 46 Progressive Effects of Low Oxygen on Modern Shelf Faunas........ 49 tne oa ie : Pete ee Figure 1-1. Figure 1-2. Figure 2-1. Figure 2-2. Figure 3-1. Figure 3-2. Figure 3-3. Figure 3-4. Figure 3-5. Figure 3-6. Figure 3-7. Figure 3-8. Figure 3-9. Figure 3-10. LIST OF FIGURES Page Location of the Central Long Island Sound Disposal Site (CLIS) ....... 3 Locations of the surveyed active and inactive disposal mounds and the bathymetric survey area at CLIS, June 1991 .............. 4 Locations and designations of REMOTS® stations over inactive mounds and reference areas surveyed at CLIS, June 1991 ........... 6 Locations and designations of REMOTS® stations over active disposal areas. CEISS June 1 99is a. escapee sac MoNesteh ewes alta ren emo 8 Contoured bathymetric chart (depth in meters) of CLIS, Dandi lS July ol99O) ke, te aN eh Sete nace, PONS UMRE, (otk odie ert = 12 Contoured bathymetric chart (depth in meters) of CLIS, QJM SLO Dy gees Va yitietce ee eee ales ot DiMA a OGG Sins NMG Gel afuch ae eee 13 Contoured chart of changes in depth (meters) at CLIS from Julyl99 Onto une 1991s hye a ie Oe ee ann Nise ascii See Oram 14 Profile plot of survey lanes 34 and 35, CLIS bathymetric surveys, NOOO KANG IOS Te Tere Sg oe EER Tae ohne Sere hee es eae eet ne 115) Map of sediment grain size major mode (in phi units) at GEIS active:disposal mounds; June 1991). 323. 352s oe 16 Map of sediment grain size major mode (in phi units) at CLIS inactive disposal mounds and reference areas, June 1991 ....... 18 Distribution of dredged material at CLIS active disposal MOUNTS FUME GEO T hoses ee ads Care Ea eae OR I ea oe alate ot we 19 REMOTS® photographs from stations M10 and NHAV-74 100E, showing “fresh” dredged material and relic dredged material, respectively 20 Distribution of dredged material at CLIS inactive mounds and reference ATCA UUM OO ies Ses te et ae Sian ice ea ame St aa cata roar 22 Map of mean small-scale surface boundary roughness values at CEIS active disposalomounds; June TO9M We as cues ocean 23 Figure 3-11. Figure 3-12. Figure 3-13. Figure 3-14. Figure 3-15. Figure 3-16. Figure 3-17. Figure 3-18. Figure 3-19. Figure 3-20. Figure 4-1. LIST OF FIGURES (cont.) Page Frequency distribution of small-scale surface boundary roughness values at the disposal site and reference areas, June 1991 .......... 24 Map of mean small-scale surface boundary roughness values at CLIS inactive mounds and reference areas, June 1991 ............ 25 The mapped distribution of apparent RPD depths (cm) at CLIS active disposalomounds. JuneslO9l. fsis 6) ee ree ae ee ae 26 Frequency distribution of apparent RPD depths for all reference areas and disposal site stations at CLIS, June 1991 .............. 28 The mapped distribution of apparent RPD depths (cm) at CLIS inactive disposal mounds and reference areas, June 1991 ....... 29 The mapped distribution of infaunal successional stages at CLIS active disposal mounds, June 1991 .................... 30 The mapped distribution of infaunal successional stages at CLIS inactive disposal mounds and reference areas, June 1991 ....... 31 The distribution of median Organism-Sediment Indices at CLIS active mounds* GFAA Zinc (Zn) 3050 6010 ICP Polynuclear Aromatic 3540 8270 GCMS Hydrocarbons (PAHs) Total Organic Carbon 9060 Grain Size ASTM D422-63 2.3.3 Metal and PAH Analyses Samples were analyzed using standard EPA procedures (Table 2-1). Cadmium and lead were analyzed by graphite furnace atomic absorption techniques and zinc by inductively coupled argon plasma emission spectrophotometry (ICP). Atomic absorption techniques with a graphite furnace allow for low detection limits. The graphite furnace heats digestates in several stages, allowing removal of unwanted matrix components. Atomic absorption spectrophotometry determinations are completed as single element analyses. Analysis by ICP allows simultaneous or rapid sequential determination of many different metals. The detection limits associated with ICP analysis are frequently higher than those with atomic absorption spectrophotometry. Polynuclear aromatic hydrocarbons were analyzed by EPA Method 8270 which utilizes gas chromatography/mass spectrophotometry (GC/MS). 2.3.4 QA/QC The NED laboratory submitted results that were acceptable and supported by appropriate documentation. The laboratory reported acceptable method detection limits, based on results obtained from the method blank processed with the samples. Several PAH Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 10 values were estimated because a particular compound was present in a concentration above the method detection limit, but below the practical quantitative limit. The practical quantification limit is the lowest level of measurement that can be reliably achieved within specified limits of precision and accuracy during routine laboratory operating conditions for a sample of a particular matrix. Quality control checks from the NED laboratory consisted of method blanks, matrix spikes, duplicate samples, and laboratory control samples. Method blanks are laboratory QC samples processed with the samples but containing only reagents. Method blanks test for contamination that the laboratory may have contributed during sample preparation. These method blanks were free of contaminants. Analysis of matrix spike samples provides a measure of the efficiency and effectiveness of sample preparation and analysis procedures. They also indicate how tightly a compound is bound to its matrix and whether or not interfering compounds are present. Matrix spikes are used to assess the accuracy of analytical measurements. Duplicate samples indicate variability in laboratory procedures and degrees of difference between individual samples. Duplicate blank spike and duplicate matrix spike samples were used to measure precision in laboratory procedures. Laboratory control samples were standard reference materials analyzed using identical procedures as for the samples. Accuracy for the reference materials was within the control limits for the metals as well as the PAHs except for one value of fluoranthene. No other QC samples indicated laboratory problems with this compound, so no qualifiers were necessary. 2.4 CTD and Dissolved Oxygen Sampling Speed of sound measurements were obtained prior to and following the bathymetric survey using a Seabird SEACAT SBE 19-01 CTD probe. The CTD was lowered over the side and allowed to equilibrate in ambient seawater for one to two minutes before initiating the cast. In addition, the CTD cast characterized depth gradients and assessed near-bottom DO concentrations relative to REMOTS® benthic analyses on and near the disposal site. The Seabird CTD collected salinity, temperature, and DO profiles at the center of the three reference areas (2500W, 4500E, and CLIS-REF) and at the center of the CLIS-90 disposal mound. Water samples from a Niskin cast approximately 1 m below the surface and 1 m above the bottom were sampled to measure near-surface and near-bottom DO values. A 300 ml subsample was drawn from the bottle, preserved, and titrated (duplicate aliquots of 50 mls) within twelve hours using a modification of the standard Winkler titration method (Strickland and Parsons 1972, Parsons et al. 1984). The intent of obtaining the titrated samples was to provide additional DO information should there be a problem with the CTD. Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 3.0 RESULTS 3.1 Bathymetry The 1200 x 1200 m bathymetric survey conducted at CLIS in 1991 covered the area previously surveyed in July 1990 (Figure 3-1). After the July 1990 bathymetric survey, the disposal buoy was redeployed in September 1990 southeast of the CLIS-89 location (CLIS- 90). The release of 59,000 m? of dredged material at the buoy formed a mound with a diameter of approximately 100 m and a minimum water depth of 16.6 m (Figure 3-2). The CS-90-1 capped mound was originally formed in the fall of 1989 and capped in the spring of 1990. It received an additional 8,730 m? of capping material during the 1990/1991 disposal season. In the 1991 bathymetric survey, the CS-90-1 mound had a diameter of 100 m and was at least 0.60 m in height (18.2 m minimum water depth) (Figure 3-2). Inactive mounds CLIS-88, CLIS-87, and CLIS-89 appeared to be unchanged between the 1990 and 1991 bathymetric surveys. A visual comparison of the 1990 and 1991 surveys (Figures 3-1 and 3-2) shows a decrease in water depth from 18.8 m to 16.6 m at the CLIS-90 buoy location. At the CS-90- 1 mound, minimum water depth increased from 18.0 m in 1990 to 18.2 m in 1991. The depth difference map comparing the two depth matrices indicated increased dredged material thickness of 2.4 m at the CLIS-90 mound and decreases of 0.2 m at CS-90-1 (Figure 3-3). The diameter of the CLIS-90 mound detected in the isopach map was approximately 200 m for thicknesses greater than 20 cm. Small deposits of material < 40 cm were scattered to the west and south of this mound. Larger decreases in dredged material thickness on the southeast side of the CLIS-87/88 mounds may be a result of inaccuracies in comparing surveys conducted over a steeply sloping bottom. The seafloor in this area showed changes of up to 2 m over 25 m (Figure 3-4). A shift of approximately one boat width (10 m) in the lane navigation for compared surveys could result in apparent depth differences of 0.5 to 1.0m. A volume calculation based on depth difference between the 1990 and 1991 survey indicated an increase of 39,503 m? of dredged material (95% confidence limits; 18,270 m3 to 60,736 m3). 3.2 REMOTS® Sediment-Profile Photography 3.2.1 Sediment Grain Size 3.2.1.1 Active Mounds Within the main survey grid, there existed a patchy mosaic of silt-clay, very fine sand, fine sand, and medium sand (Figure 3-5). A large part of the surveyed area, particularly over the most recent disposal mounds, showed very fine or fine sand, reflecting the effects of disposal. The presence of silt-clay mud patches within this area apparently Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 (Ee Ye oo] a ia = % Oh Wale oR NZ ee 4 7S 2 EX ira o = BS — CLIS-87 — “7a CLIS-88 — 072 54.000W Meters T {00200 300 400 500 Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 Contoured bathymetric chart (depth in meters) of CLIS, 17 and 18 July 1990 Figure 3-1. 13 1661 OUNE 1Z ‘SITD Jo (Sioa UI IWdap) yeYS sINeWAYIeG paInojwoD °7-€ andy tl 4 Z fe ty I, 43 Ve OK ‘5; Vost Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 (Ss) oO) (ie) KH oe j=) a = (ep) cp) — oe @&) LLJ 5) PE, LL ag Li [eies Heres — (a=) mo eT ak LJ (==) Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 Contoured chart of changes in depth (meters) at CLIS from July 1990 to June 1991 Figure 3-3. Oestn Oestn Oepth WwW E 120 a0 lane 34 160 18 0 ee 200 20 1990 0 100 200 300 400 S00 Let i} 700 600 0 {000 1100 1200 Bistance 120 140 lane 34 160 180 20.0 22.0 4991 0 100 200 300 400 me 700 600 900 1000 1100 1200 120 ne lane 35 16.0 18.0 20 22.0 1990 0 100 200 300 400 S00 0 700 800 300 1000 4400 1200 Oistance 12.0 ano lane 35 160 18.0 ae 1991 22.0 t) 100 200 30 400 500 600 700 600 900 1000 1100 1200 Distance Figure 3-4. Profile plot of survey lanes 34 and 35, CLIS bathymetric surveys, 1990 and 1991 Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 166] oung ‘spunour jesodsip aaoe SyTD 1 (sun tyd ul) spour Jofew azis ureId JUoUTIpas Jo de *S-¢ JANI | N.GZ'60 olt a TG \ SS = N.0S°60 ol (ud 1-z) pues wnipoyy FRY (iyd z-€) pues aug ROY SPUNO|| 9AILOV (1ud €-p) pues auly Asap KN] L-06-SD $0 Aenins =V7 Wud p<) Aeioans [7] pup uoneis-99 = © SOW JOIEIA eZIS/MIEIE) L6 SI19 Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 17 reflects both the presence of ambient bottom conditions (parts of the seafloor not yet covered with dredged material) and fine-grained mud that represents disposed materials. Grain size information from CLIS-88 and CLIS-89 surveys that overlaps the sixty-six-station grid has been incorporated into the distribution of grain size in the area (Figure 3-5). RYyAaI 4 Inactive Mounds and Reference Areas The grain size major mode for inactive mounds CS-1, MQR, FVP, and NHAV-74 was mostly silt-clay (>4 phi). On mounds CLIS-88 and CLIS-89, the very fine sand and the fine sand, respectively, may be the result of extensive dredged material disposal in the area over time. The natural ambient bottom in the central Long Island Sound basin within and surrounding CLIS consists of brown to grey silt-clay mud (>4 phi) (Figure 3-6). Silt-clay was the dominant textural mode for CLIS-REF, 4500W-REF, and most of the 2500W-REF. Five stations at the 2500W-REF had a major textural mode in the 4-3 phi range. The water depth at this western reference area (13 m) is shallower than the CLIS-REF and the 4500E- REF areas. This very fine sand mode probably reflects the proximity of the western reference area to the mud-sand transition at approximately the 13 m depth contour in this part of the Sound (see NOAA Chart 12354). 3.2.2 Distribution of Dredged Material 3.2.20) Active Mounds The CLIS-90 and CS-90-1 disposal locations at CLIS were in an area that received spatially dispersed dredged material over the past few years (Germano et al. 1993). All REMOTS® photographs in the CLIS survey area showed the presence of dredged material (Figure 3-7). Within the main survey area, the sediment is either fresh or relic dredged material based on sediment grain size, optical reflectance, and sediment fabric (SAIC 1990; Figure 3-8). The fresh dredged material followed a NE -SW trend through the center of the survey over the CLIS-90, CLIS-89, and part of the CS-90-1 mounds. Isolated patches of relic and fresh material occurred at one or two stations near the edge of the survey area. BAI Inactive Mounds and Reference Areas The REMOTS® survey at the three reference areas detected only ambient sediment. Relic or more weathered dredged material was concentrated in the REMOTS® grids over inactive mounds CS-1, NHAV-74, and FVP. Station 100E at FVP was classified as fresh dredged material due to very dark reduced sediment at depth. At MQR, the REMOTS® photographs showed silt-clay dredged material with layered or chaotic fabrics, the presence of methane gas, and low reflectance of sediment below the RPD (resulting from high sulphide content). These are all characteristics often attributed to recent or fresh dredged material, but can also be indicative of retrograde conditions. Because there was no recent Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 1661 oUNG ‘seoIe aDUdIOJOI pue spunour [esodsip aanoeul sO Je (sun 1yd ur) spour Jofeu ozis uIeI3 JUoUIIpas Jo dep *9-¢ aaNS1q 43Y4-SI1D sualaW ooot 008 00v N S x a e ° N w 2 CY a ° = = = (1ud [-Z) pues wnipayy Fay ud z-€) pues auly BOC SPIjIV VOUDIIJABY PUP SPUNO|] SAI}OeU| (ud g-p) pues aury Asay [X_N 1 (ud p=) Aeionis Fag “BPOIN| JOleW EZIS UleID L6 S119 Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 19 1661 ung ‘spunow jesodsip aatoe ST ID Ie [elJa}eUI pasposp Jo uoNNGINSIQ °L-¢ BNI juawipas juaiquy [| jevarey pebpaiq 84 KXNY jevayey pabpeiq ysaiy / 7 | % N.G2Z'60 ol ‘ay ¥ N.0G°60 ol? 1-06-SO Jo Aening = V7 pup uoneis-99 = ‘UOHINqUIsiG jevaIeW) pebpaiq | G S|]D SpuNO|| 8AIDV Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 20 AJoatjsadsal ‘[elloyeul pospoip d1[91 pue jeLojeu paspaip ,.Ysoyj,, SUIMOYS “YOOT PL-AVHN PUR OTIN suores wor sydeisojoyd gS LOWY A001 vL-AVHN Ol W "S-€ andi] Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 21 disposal at MQR, the apparent retrograde recolonization at MQR could be the a result of physical disturbance. It is also possible that these results indicate that the relic dredged material at these stations has inhibited extensive bioturbation activity (see Section 3.2.5.2). At CLIS-88 and CLIS-89, the stations closest to the active disposal locations display recent dredged material while the stations to the north and west contain relic dredged material (Figure 3-9). 3.2.3 Boundary Roughness High boundary roughness produced by physical processes such as erosion or deposition of cohesive materials is typical of newly deposited dredged material. Old or relic dredged materials, particularly on the distal parts of mound flank deposits, have low boundary roughness due to “smoothing” by currents, small-scale bioturbation, and filling-in of relief from natural deposition (Figure 3-8). 3.2.3.1 Active Mounds Over the main REMOTS® survey grid, boundary roughness values were low with most values being less than 3 cm. Only two stations had boundary roughness over 3.0 cm (IS and M10). These stations were located (respectively) within 100 m of the CLIS-90 buoy and CS-90-1 mounds, and it is likely that this high relief is related to the recent deposition of dredged materials (Figure 3-10). Boundary roughness values at the disposal site stations were not significantly different from those at the reference areas (Figure 3-11; Mann- Whitney U-test, p=.824174). S223 22 Inactive Mounds and Reference Areas All of the mean boundary roughness values at CS-1, CLIS-88, CLIS-89, FVP, and NHAV-74 were less than 3.0 cm. This indicates that remolding processes such as hydrodynamic “smoothing”, deposition, and biological reworking have reduced the high relief associated with cohesive fresh dredged material at these inactive disposal mounds. At MQR, the boundary roughness value was 3.0 cm at 300W due to a sloping sediment water interface. Boundary roughness values at the three reference areas were all less than 2 cm (Figure 3-12). 3.2.4 Apparent RPD Depth 3.2.4.1 Active Mounds In the disposal area grid, five stations had mean RPDs greater than 3 cm. Most stations had RPDs that fell within the class >1 cm and <3 cm. Where RPD depths were Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 22 166] oun 43Y¥-SND 6 S¥IIe IUIIOJOI PUL SPUNOU SATIOUI STC Je [elJajeul pasparp jo uoNINsSIq °6-¢ 2NSIY N NS ° oa po So M.S°7S07Z M jevajeyy pabpaig epesBonay KAA) yuawipas yuaiquiy [__) jeuayeyy pabpaiq say K XN) jevuajeyw pabpaiq ysaiy P77] SEC oooL 008 00v N.9°800 Lv N.O'600L¥ Sealy a80uUaJaJayY pue SpuNo|| dAI}OeU| ‘UOIINUISIG JeUaIeV\) pebpaig L6 SIND Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 ~ N 1661 aung ‘spunoul [esodsip aaoe S] TO Je sanjea ssauysnol AJepunog ddvjIns a]edS-][eWIs URIUI Jo dey] “O[-¢ aNd £0 ev Viiv 1-06-89 Vv SV ‘O “1 49°09 € Z swap inowuog 1-06-S9 30 Aaning = V7 PUD uoNeIS-99 = yw N.GZ'60 ol N.0S'60 ol spunoy |esodsiq aaioy -ssauyBnoy Alepunog ural] | G SI]D Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 24 166] oung ‘svarIe aoUaTajaI pue ajis [esodsip ay) ye sanjeA ssouysnos Alepunog soezINs a]eds-|[eWIs Jo UONNGIsIp Aouenbal.J *{I-¢ 3 an3iy ssauyBnoy Asepunog ssauyBnoy Asepunog tt Ol 6 8 £9 G&G bv € Z@ WUOWE 628s 39] (GbE aca by 0 on -=— Qwotanooran Aouanbeas4 Aosuanbas4 ov cv BE vE Oe - 9°~ ce BL vl OL 9°0 FKFNMOMTNORDOD (wo) sane eAJa\uU = jo ebuey Nese. 99=N L661 eunr Aay aus |esodsiq SI19 6€ = N L66L Aine seal aoualajay S|19 Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 25 QOUdIIJOI PUL SPUNOUI SATORUT STTO Je Sanjea ssauysnos AlepuNog sdeJINs a[eds-|[eWs URDU Jo dey *Z]I-E JINdIy 43u-SI1ID Ol Ll? 80” bplLLOo vl vvweoeg iw 60” Lov 60" Auepunog eiis jesodsig M.S9°2S0cL €— < s}iwijap snoyuoD 166] sung ‘seole ow oo SUNG Aes EA uw V¥V VT on se el | 434-MO0Sz viv OLVv LEU Wr, se ; VIEL OL BL 80 LL 6 ne, Fel as Des Fok Haren 2 60 a Ely LLY seal adUaJaJay pue SpUNO| aAI}DeU| ‘ssauybnoy Asepunog ueal/\ L6 SI1D Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 166] eung spunoul [esodsip aanjae SJ 38 (wD) sy;dap Gqy JUaredde jo uoNNqiNsip paddew sy], =O ee 2 CLO h €I-¢ aansiy N.0S°60 ol wo | Se spuno|\| 8ANOY woe <~ WH ean aninae= -(W9) yidag Gdy Juaseddy uea\ L6 SII9 pup uonels-99 = w Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 P47 < 1 cm deep, the stations cluster together, aligning in a NE-SW orientation over CLIS-90 and north of CS-90-1 (Figure 3-13). Based on the original sixty-six-station grid over the active mounds, and the reference areas, the RPD values were significantly different between the disposal site and the reference areas (Figure 3-14; Mann-Whitney U-test, p< 0.001). 3.2.4.2 Inactive Mounds and Reference Areas All three reference areas had mean apparent RPD depths greater than 1 cm. Nineteen out of thirty-nine stations had RPD depths greater than 3 cm (Figure 3-15). Inactive mounds FVP and NHAV-74 had RPD values similar to 2500W-REF and 4500E-REF. At MQR, eight stations located near the center of the MQR mound apex (100E, 100N, 100S, 100W, 200E, 200N, 200W, and CTR) had mean apparent RPD depths that were anomalously shallow relative to the three reference areas. Inactive mounds CS-1, CLIS-88, and CLIS-89 had one station with RPD depth less than or equal to 1 cm, eight stations greater than 3 cm, and thirty stations between | and 3 cm. 3.2.5 Successional Stages 3.2.5.1 Active Mounds Within the survey area, the only apparent successional stage pattern involving several stations was the NE-SW orientation over CS-90-1 and CLIS-90, and stations clustered on the _ eastern side of the survey, with only Stage I taxa (Figure 3-16). Isolated areas of azoic (station E5), Stage I, and Stage II organisms occurred where dredged material was deposited within the last two years (Germano et al. 1993). BA" Inactive Mounds and Reference Areas All stations within the three CLIS reference areas contained Stage III infauna except for 100W at the 2500W-REF area (Figure 3-17). On the inactive mounds, Stage III fauna predominated. Only Stage I fauna was present at CS-1 300E, and MQR 200N, 200S, and 200E. 3.2.6 Organism-Sediment Index The multiparameter REMOTS® Organism-Sediment Index (OSI) characterizes habitat disturbance. The parameters used to calculate the OSI values are the mean apparent RPD depth, the presence of methane or the inferred absence of dissolved oxygen in surface sediment pore waters, and the successional stage (SAIC 1989). Based on the results of past REMOTS® surveys, OSI values < +6 indicate a recently or chronically stressed benthic habitat (e.g., erosion, dredged material disposal, hypoxia, demersal foraging, etc.; Rhoads and Germano 1986). Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 28 1661 9unf ‘STTO JB SUONEIS ajIs [esodsip pue svase doUaIaJaI [Je 10} s—dop Gay Joredde jo uoNnqisip Aouenba1y ‘pyt-¢ aindiq yideq Gd ueeyy uidag Gdy uray) Gil ThOl G2 6 to eat ELZLILLOL6 BLYXYGrETZL OL n g'9 a 0'9 mn a 09-G'G Ps) 2 GG-OSs a c 0'S-S"p ae 3 Gv-OV 2 2 Ov -S'E 2 GE-O€ Oe-G7 Gz -0'2 0c oc-GL GL-O-L ol-g'O $0 -0'0 Gz 6E=N (wd) sanjeA —- JeAJAUY v9 =N LG6L eunr jo eBuey sse|9 L6GL eunr ays aduaIajay SID Aay aus jesodsiq S19 Oe Monitoring Cruise at the Central Long Island Sound Disposal Site, June 199] 1661 UNE ‘svore adUdIAJOI pue spunoul [esodsip aatjoeul S]JO 3e (Wd) sy\dop Gay Joredde Jo uoNnqiNsIp poddew oy], “S{-¢ ainsi 97 Vv Asepunog ails jesodsig N.9'800L¥ N.0'600lLv N N ° a is) oy = M.0°¢S0eL seal aduaJajJay pue Spunoyy dAi}OeU; -(wd) yidaq Gdy }JUaseddy ues L6 SID Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 166] ung ‘ spunoul jesodsip aatjoe S] JO Ie SoseIs [eUOISSadONS JeUNLJUI JO UOINGINsIp paddeu sy], “gT-¢ aaNsig N.S2°60 ol N.0S°60 ol \| Bers puohag paouenpe @ Sspuno| jesodsiq 9AI]OVW you sey snje}s jeuoIsSsadoNS SUC nel ‘sabels jeuoissa99ng =| G S|] (payeosewap Jn0jUOd) AjuO | aBeIS O Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 31 166, une ‘seale d0UdIOJOI pue spunoul Jesodsip OATJOVUT STTD ye sa3se}s [euolssaoons [eUNeJUI JO UOTINIASIp poddeur UL “LI-€ ainsiyq 43u-SI19 N.O'600L 43aYu-MOO0SZ M.G°ESooL o10zy B || @Berg puohag paouenpe @ SBAJI\/ BDUBIBJ9Y Pue SPUNOWy SAI}OeU| you sey snjejs jeuoissa2ons juesaid j|| abeis V7 ‘sabes JEUOISSB89ING L 6 S me) (payeosewap snojuod) Ajuo | aBeiIg OC Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 i 32 3.2.6.1 Active Mounds Within the CLIS survey area, median OSI values ranged from 0.5 to 10. Lower values predominate in the area of the two active mounds, CLIS-90 and CS-90-1 (Figure 3-18). OSI values were also less than +6 south of CLIS-89 and in the northwest area of the survey. Where the median OSI value is +0.5, (southwest of CLIS-89) there appeared to have been recent trawling or other physical disturbance. Between the original sixty-six- station grid over the active mounds, and the reference areas, the OSI values were significantly different (Figure 3-19; Mann-Whitney U-test, p< 0.001). 3.2.6.2 Inactive Mounds and Reference Areas On the inactive mounds, FVP, MQR, and NHAV74, the OSI values were not significantly different from the main REMOTS® survey area (Mann-Whitney U-test, p=0.374, 0.512, and 0.513, respectively). At NHAV-74 and FVP, the OSI values were greater than +6 for most stations. On the MQR mound, most OSI values fell between +1 and +3 cm. On CLIS-88 and CLIS-89, OSI values ranged from 4 to 11. The median OSI values for the three reference areas were predominantly greater than OSI= +6 (Figure 3-20). 3.3. Sediment Analysis 3.2.1 Grain Size and Total Organic Carbon Grain size analyses were conducted on samples retrieved from the center of 2500W- REF, 4500E-REF, and CLIS-REF (Table 3-1). All samples were dark grey clay-silt with shell fragments. The percentage of sand versus silt/clay was similar for all the reference areas. Of the silt/clay fraction, silt dominated at all three areas. Grain size results were 87% silt/clay and 13% sand for 2500W-REF and CLIS-REF. The sample from 4500E-REF was 12% sand and 88% silt/clay. These results corresponded with the grain size major mode determined by REMOTS® for 4500E-REF and CLIS-REF. The REMOTS® grain size determination at the center of 2500E-REF, very fine sand (4-3 phi), was coarser than the silt/clay determined by grain size analysis. REMOTS® stations 100 m away from the center were consistent with the laboratory grain size analysis. The average percent TOC was highest at 2500W-REF (1.05%), followed by 0.89% at CLIS-REF, and 0.83% at 4500E- REF. 3.3.2 Metals Cadmium (Cd), lead (Pb), and zinc (Zn) were detected at all three reference areas. Values for cadmium ranged from 0.15 to 0.28 ppm; lead 51 to 76 ppm; and zinc 130 to 210 ppm. Replicate values were within approximately one standard deviation of the mean (Table 3-2). The average values for Cd, Pb, and Zn were slightly higher at 2500W than at Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 33 the other reference areas. CLIS-REF and 4500E showed similar average values for Cd, Pb, and Zn. Table 3-1 Results of Sediment Grain Size Analyses and Percent Total Organic Carbon (TOC) for CLIS Reference Areas, June 1991 Dark grey Dark grey Dark grey clay-silt with clay-silt with clay-silt with shell fragments Shell fragments shell fragments % Coarse Sand (1 to -1 phi) % Medium Sand (2 to 1 phi) , % Fine Sand (4 to 2 phi) Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 34 Table 3-2 Metals Results (ppm Dry Weight) for Sediments Collected at the CLIS Reference Areas, June 1991 Metals Cd Zn (ppm dry weight) Average 1SD Average 1SD Average 0.16 60 133 1SD 0.04 2 5 Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 Contours Delimit OSI < +6 ° a | oc x< ® 2) S ~ Cc ® £ x2) ( = O WuIap sunojuoD Sealy 90Ud19Jayy pue spunoy| aAijoeU| ‘x@pu| JUaWIPaS-LUSIUeBIC UeIPA/\ L6 SID Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 38 3.3.3 PAHs Replicate PAHs at each reference area were more variable than results for the metal analyses; values fell within two standard deviations of the mean (Table 3-3). Several values were qualified as estimated (J values) indicating that a compound was present in a concentration above the method detection limit and below the practical quantitation limit. Of the low molecular weight (LMW) PAHs, phenanthrene was the most abundant at all three reference areas with average values of 167 ppb at CLIS-REF, 173 ppb at 4500E, and 247 ppb at 2500W. The average value of naphthalene, 127 ppb, was also higher at 2500W in comparison to the other two reference areas. Fluorene, acenaphthene, and acenaphthylene were below detection limit at CLIS-REF and either found in low concentrations or below detection limit at 4500E and 2500W reference areas. Total LMW PAH values were highest at 2500W and lowest at CLIS-REF. High molecular weight (HMW) PAHs were detected at all the reference areas, except for dibenzo(a,h)anthracene, which was below detection limits at all the reference areas, and indeno(1,2,3-cd)pyrene, which was below detection limits at 4500E and CLIS-REF. Concentrations were greatest for pyrene with average values of 373 ppb at CLIS-REF, 410 ppb at 4500E, and 607 ppb at 2500W. Fluoranthene was also detected in higher concentrations relative to the other HMW PAH compounds: 257 ppb at CLIS-REF, 287 ppb at 4500E, and 423 ppb at 2500W. Total values for HMW PAH compounds were greatest at reference area 2500W, followed by 4500E and CLIS-REF. 3.4 CTD and Dissolved Oxygen Sampling All water column measurements were made on June 18 to facilitate comparisons between sampling stations. The water column overlying the three reference areas and CLIS- 90 buoy location had similar temperature-salinity structure with a strong midwater pycnocline from 1 m (2500W-REF) to 12 meters (CLIS-REF) (see Appendix). Below the pycnocline, temperature and salinity remained constant to the bottom (total depth at 2500W = 13 m, 4500E = 20 m, CLIS-REF = 17 m, CLIS-90 = 18 m). The 2500W REF station had a 1.5 m thick isothermal surface layer 1°C higher in temperature than the other areas. Temperature and salinity were constant below 11 m. Dissolved oxygen profiles at 4500E-REF, CLIS-REF, 2500W-REF, and the CLIS-90 mound decreased from the surface to the bottom water. Dissolved oxygen below the pycnocline was lower than concentrations above the pycnocline by 2 to 3 ppm. The concentration of DO in bottom water ranged from 6 to 7 ppm at all stations (Table 3-4). Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 ‘yw UoeyQuenb jeogoeid ueYY ssay yng ‘yWuw] UORO@Jep UeY) 19)2016 ‘enjeA payewigs; = ¢ (>) uoQaejep Mojaq Byep 10) SUOQejNd]e9 U! pasn yw) UOROaJep ‘UBa OY) Wd) UOHe|AeQ PiBpUeIS | ‘OSL WLOL euesAd(po-¢'z' | ouspu; eue|Aied()'y'6)ozueq euedByUB(Yy'e)oZUeqIp euelAd(e)ozueq eueEyjuBION|)(4)oZUEq euayjUBION(q)ozueq euesAiyo euedeBsyjue(e)ozZuEq euelAd eueywesON|) we seinoej0Wy YOIH euejeyyydeu |Ayjow-z euejeuyydeu wWBje JejnNdejOyy MO? ywr uoN[eag POULEIN /UBaW | wBjem Ap (qdd) sHvd 166] ‘Bal a0UaIIJay SITO ay) 1k paydajjoo SJUSUIPSS oJ (IYsIaA\ A1q qdd) saskjeuy HWd Jo sinsoy €-€ FGeL Monitoring Cruise at the Central Long Island Sound Disposal Site, June 199] & Table 3-4 Dissolved Oxygen Concentrations at Selected Disposal Site and Reference Stations at CLIS, June 1991 (Concentrations are in mg’) Station At Bottom CLIS-REF 6.77 4500E 6.60 2500W 6.30 CLIS-90 6.50 Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 4.0 DISCUSSION The following discussion addresses the four major objectives of the 1991 DAMOS CLIS survey: to define the topography and footprint of the active disposal mounds, to evaluate the successional status of active and inactive disposal mounds, to collect sediment chemistry information at the three reference areas, and to determine the potential role of bottom water dissolved oxygen as an ecological variable. 4.1 Disposal Mound Topography The objective of the combined REMOTS® and precision bathymetric surveys was to delineate the extent and topography of the deposit resulting from dredged material disposal at CLIS since the 1990 survey. At the CS-90-1 buoy location, material released in 1989 had been capped since 1990. The CLIS 1991 survey was also designed to detect any of the material released at CS-90-1 since 1989. The bathymetric survey showed a significant accumulation of dredged material near the CLIS-90 disposal buoy and smaller amounts at the CS-90-1 buoy. However, the radius of the CLIS-90 disposal mound detected by the bathymetric survey (>20 cm thick above ambient bottom) was 100 m rather than the predicted 200 to 250 m (Figure 3-3). Based on the detection of dredged material by REMOTS® (< 20 cm), “fresh” and relic dredged material is present over the whole survey area. “Fresh” dredged material extends more than 100 m south of CS-90-1 and north and west of CLIS-90. The distinction made between “fresh” or recent dredged material, and relic or older dredged material, is based on a “fresh” signature exhibiting thin or patchy RPDs (redox potential discontinuities), physical layering or chaotic sedimentary fabric near the surface due to a lack of bioturbation, and high boundary roughness. The “fresh” appearance to the material in these areas may be due to the low metabolic rate of infauna over the winter (including bioturbation rates) resulting in thin or patchy RPDs. A plot of reported barge release points for the 1990/1991 disposal season at CLIS indicates that most of the barges released dredged material within 250 m of the CLIS-90 and CS-90-1 buoys (Figure 4-1). The presence of dredged material at all REMOTS® stations in the main 1991 survey grid reflects the extensive use of this quadrant of CLIS for dredged material disposal over the past few years. A disposal mound has been formed within the 1991 survey area every year since 1987. Previous surveys have noted dredged material disposal away from the intended locations (Germano et al. 1993). At CS-90-1, however, the material was intentionally released at various locations away from the buoy to spread cap material around the CS-90-1 mound. Monitoring Cruise at the Central Long Island Sound Disposal Site, June 199] uoseas [esodsip 16/066] 2U) SulINp STJO Je sjulod aseajar a81eq payodsy *J-p aunsiy ® 88-Ssia : © 28-SI19 06-SI19.6° + 7 4 + + 1-0b-s9@ ©.68-SI19 + aad + V6sT 10 Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 43 According to log estimates, barges deposited 88,588 m3 of dredged material at CLIS during the 1990/91 disposal season. A volume calculation based on the depth difference between the July 1990 and June 1991 bathymetric survey at CLIS was 39,503 m? of material. The depth difference between 1990 and 1991 includes not only material added to the area during that time but also any compaction of material that has occurred. Tavolaro (1984) showed that volume estimates based on barge logs overestimate the amount of transported dredged material because of the significant amount of interstitial water associated with the material in the barges (“fluffing”), and the detection limitations of bathymetry. He calculated that “depth difference” volume estimates based on successive bathymetric surveys can be as much as 41% less than the barge log volume estimates. The discrepancy was attributed not only to log inaccuracies (due to limitations inherent in measuring dredged material volumes in the barge) but also to compaction of dredged material on the bottom following disposal and the significant volume of material that is deposited on the flanks of the mounds in layers too thin to be detected acoustically. Applying the 41% factor to the log estimate of 70,624 m3 for dredged material actually released at CLIS resulted in a corrected barge log estimate of 41,668 m3. This corrected estimate is 100.5% of the volume of material detected by the bathymetric survey (39,503 m3). 4.2 CLIS Successional Status The predicted recolonization status at CLIS was Stage I on the CLIS-90 and CS-90-1 mounds, progressing to Stage III on the inactive mounds. Both the CLIS-90 mound and CS- 90-1 mounds had Stage I taxa at the center, but stations around these mounds have apparently retained a Stage III status. Burial of Stage III taxa by thin layers of dredged material does not kill these organisms as they are capable of burrowing upward through the deposited layer to reestablish connection with the new sediment-water interface (Goldring 1964, Kranz 1974). Stage III organisms were expected at all of the reference areas and inactive mounds. At the reference stations, Stage III taxa predominated with only 2500W-REF, station 100W, having only Stage I infauna. On the inactive mounds, CS-1, CLIS-88, CLIS-89, NHAV-74, and FVP all exhibited Stage III seres. This observation supports convergence between the successional status of old inactive disposal mounds and the ambient bottom. The exception was CS-1, 300E, that had only Stage I. The scattered locations where Stage III was not detected may have been mischaracterized, or a consequence of natural benthic patchiness as also observed at 2500W-REF. The recognition of Stage III seres in REMOTS® photographs depends on the development of subsurface feeding voids. The CLIS 1991 monitoring survey was conducted in the late spring when low sediment temperatures depress the metabolism and feeding rate of Stage III worms (D. Rhoads - pers. comm.). This results in less well- developed feeding voids at depth in sediments and can result in inaccurate successional stage characterization. Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 R At the inactive MQR mound, stations 200N, 200S, 200E, and 100E had only Stage I seres. Because the prevalence of Stage I organisms was higher here than at any other mound, and because of the low RPD values at this area, the apparent lack of Stage III organisms at these locations may indicate, according to the DAMOS tiered monitoring protocol, that further monitoring and management is needed. MQR received contaminated dredged material from such projects as Mill and Quinnipiac Rivers, Black Rock Harbor, and New Haven Harbor between 1982 and 1983, warranting further investigation. Fresh dredged material has a lack of biological activity and an increased sediment oxygen demand compared to the ambient sediment. This accounts for the significantly shallower RPD depths for the disposal site stations versus the reference stations. Trawling over the sediment surface also may result in loss of the RPD signature by removing sediment at the surface. Some evidence of trawling activity is seen near longitude 72°53.5' W, stations E5 and D7. Localized areas of oxidized sediment layers greater than three centimeters deep were observed near CS-90-1, CLIS-87, and in the northwest corner of the survey area. Deeper bioturbation by the local infaunal assemblages causes the increased RPD depths in these areas. The mean apparent RPD depths on the NHAV-74 mound are deeper than those at the MQR mound, but this could be attributed to the higher concentration of organic matter in the MQR material. 4.3 CLIS Reference Area Chemistry The three CLIS reference areas have chemical signatures consistent with this part of Long Island Sound and appear to be suitable as references for monitoring the site. As a set of baseline chemistry data, this report will help in monitoring any future changes in sediment chemistry associated with the reference areas. Data from CLIS reference areas are compared to samples analyzed previously for Cd and Zn by the NED laboratory in 1986 and 1987 (Table 4-1). The values have remained unchanged (Tables 3-2 and 4-1). PAH baseline information at the three reference areas showed concentrations of HMW and LMW PAH compounds were greatest at 2500W, and were similar at 4500E and CLIS-REF (Table 3-3). The higher TOC content at 2500W may have provided additional binding sites for the metals and PAHs analyzed (Table 3-1). This would explain the higher levels of metals and PAHs at 2500W compared to the other two reference areas. Also, 2500W is closer to shore and may receive higher input rates. Sediment grain size commonly correlates with both metallic and organic contaminants in sediments. Studies of both natural and polluted sediments have demonstrated that higher concentrations of contaminants are usually associated with the fine-grained fraction (silt/clay) of sediments (Forstner and Wittman 1983, Kennish 1992, Pequegnat et al. 1990). Particulate and colloidal organic matter, because of its fine grain size, surface charges, high surface area to volume ratio, and microbial coatings, serve to adsorb or chelate organic and metallic Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 contaminants. In the following comparisons of CLIS reference area data to regional data, values are normalized to the percent silt and clay content because of the regional variation of grain size and organic content (Table 4-2). Table 4-1 Metals Concentrations (ppm Dry Weight) in Sediments Collected at NLON, CLIS, and WLIS in 1986 and 1987 Metals ppm dry weight NLON-REF 1986 1987 CLIS-REF 1986 1987 2500W 1987 4500E 1987 WLIS-REF 1986 1987 2000S 1987 2000W 1987 NA=Not analyzed ND=Not detected Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 0000 000°0 ZeL t 606 bt 000'0 000°0 vS8' bh O9Ss' ht 96S 92 89682 punos puejs} Buo7 wiaysa\\ pue|s| Pla!YaUS Joquey uoyununy JaAy a1u0JesNnOoH uaAeH MON :suolje9077 ajdwes euasAd(po-¢'z'})ouapu| eua|Aad(I'y'6)ozuag euacesyjUe(y‘e)oZUaqiGg euasAd(e)ozuag auayjuesony(y)ozuag auayjuesoni(q)ozuag euashiy9 euaoB sue (e)oZUag aualky auayjUueJon|4 WIAA JeINDa|OW YO!H SHWd MW 18101 eusoBiujUY euaJyjueUayd auaion|4 auayjydeuaoy euajAyjydeusoy euajeyydeujAyjap-z euajeyyudey WBiaM Je|NDa|OW M07] oulz pea wniwpe9 (Ab{D puke IIg) UOINDeI{ PouleIH UI] yUadIEg OY} 0) PaZI[eULION sUOTeIIUIDUOD [|TV ‘SPIIY IOUBIIJIY SITIO YM BEG LSN S,VWVON Jo uostiedui0g $ LA Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 Data collected as part of the National Oceanic and Atmospheric Administration’s (NOAA) National Status and Trends (NS&T) Program were compared with the CLIS data to provide a frame of reference (Table 4-2). The NS&T Program has collected and analyzed coastal and estuarine sediment data from 300 sites since 1984. Several sites in Long Island Sound that were sampled over the period of 1984-1989 (NOAA 1991) were compared to the CLIS reference area data. The three sites closest to CLIS, including New Haven Harbor, the Housatonic River, and the East Long Island Sound station (located approximately 50 km east of CLIS) are all sandy sites, with a combined silt and clay percentage of less than 10%. Although these sites are closest geographically, several sites west of CLIS were chosen with more comparable grain size ratios and included with the CLIS comparison (Table 4-2). In addition, all NS&T data are normalized to the fine-grained fraction to compensate for the variation of grain sizes. The correlation between the fine-grained fraction and trace chemical constituents for the NS&T data was higher than with Al or TOC (NOAA 1991). The CLIS data were also normalized to the fine-grained fraction for comparison purposes. Normalized metals results from the CLIS reference areas were less than metals concentrations measured at the NS&T sites (Table 4-2). All the metals concentrations fall below the “low” category for contaminated sediments suggested by the New England River Basin Commission (Oceanic Society 1982). Total LMW and HMW PAHs from the CLIS reference areas were also compared to the NS&T sites. PAHs are organic trace contaminants in estuarine and marine environments and consist of carbon and hydrogen arranged in the form of two or more fused benzene rings in linear, angular, or cluster arrangements. They encompass a wide range of chemicals, with the principal sources in estuaries including industrial and municipal wastewater effluents, oil spills, combustion of fossil fuels, commercial and recreational boating activities, riverborne influx, dredged sediments, nonpoint source runoff of materials from terrestrial habitats, and in situ diagenesis of organic matter in sediments. The major sources of PAHs in the aquatic environment are petroleum spillage and atmospheric deposition (Kennish 1992). Low molecular weight PAHs (including naphthalenes, anthracenes, fluorenes, and phenanthrenes) are more soluble, more volatile, and acutely toxic to some organisms, but are noncarcinogenic. LMW PAH compounds originate principally from fresh, unburned petroleum (Kennish 1992). Higher molecular weight PAHs (containing 4 to 7 rings) are carcinogenic, mutagenic, or teratogenic to a wide variety of organisms, including fish and other aquatic life (Kennish 1992, Pequegnat et al. 1990). These compounds are less volatile and have longer residence times in the aquatic environment. They include fluoranthene, pyrene, benzo(a)anthracene, chrysene, benzo(a)pyrene, and benzo(g,h,i)perylene. HMW PAH compounds are generally derived from fossil fuel combustion (Kennish 1992). It is Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 48 currently thought that pyrogenic PAHs are more tightly bound to the particles than petroleum source PAHs (McGroddy et al. 1992). As PAHs enter water from various sources, they quickly become adsorbed onto organic and inorganic particulate matter, and large amounts are deposited in bottom sediments. Once in bottom sediments, PAHs may undergo biotransformation and biodegradation by benthic organisms. The principal degradative processes for PAHs in the marine environment are photoxidation, chemical oxidation, and biological transformation by microbes and aquatic animals (Kennish 1992). Total LMW and HMW PAHs normalized to grain size from the CLIS reference areas were higher than three of the NS&T sites (Eastern Long Island Sound, New Haven Harbor, and Huntington Harbor) and lower than three sites (Housatonic River, Sheffield Island, Western Long Island Sound; Table 4-2). Of the six NS&T sites, only two are not nearshore sites: Eastern (ELI) and Western (WLI) Long Island Sound. The fact that the CLIS data fell between these two sites is consistent with the central Long Island Sound location. There were a few individual PAH compound concentrations measured in CLIS reference samples that were exceptions to the trend shown by the total LMW and HMW values. Benzo(b)fluoranthene, benzo(k)fluoranthene, and benzo(g,h,i)perylene, all HMW PAHs, had higher concentrations in CLIS samples than all of the NS&T sites. Concentrations of acenaphthylene (LMW) and indeno(1,2,3-cd)pyrene (HMW) at the CLIS reference areas were higher than all of the NS&T sites except for WLI (Table 4-2). 4.4 Bottom Water Dissolved Oxygen Dissolved oxygen concentrations in bottom water at both the CLIS-90 buoy mound and the three reference areas were comparable and high relative to the physiological requirements of macrofaunal organisms (Table 4-3). The objective of the CTD/DO sampling was to assess near-bottom DO concentrations relative to benthic habitat conditions within the reference areas and at the active disposal point. Bottom waters, ranging from 6.3 to 6.77 ppm DO, were all within the aerobic range (Table 4-4). Low DO levels do not affect the behavior or structure of benthic assemblages until the concentration decreases to the hypoxic threshold of 2 ppm (Tyson and Pearson 1991). The absence of hypoxia means there was no regionwide hypoxia effecting the area. Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 Table 4-3 Progressive Effects of Low Oxygen on Modern Shelf Faunas; From Tyson and Pearson, 1991 Dissolved Oxygen Range (mg‘I') Effect on Fauna 2.8 - 1.4 Avoidance and migration by nekton and some mobile epifauna. 2.0 - 1.4 Behavioral responses to stress by stenoxic benthic fauna. 1.4-1.0 Emergence of euryoxic infauna. 1.4 - 0.7 Physical inactivity. Duration or severity of conditions exceeds homeostatic capabilities and mortalities. Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 50 5.0 CONCLUSIONS In 1991 the Central Long Island Disposal Site (CLIS) survey revealed that active disposal in 1990-1991 created a stable mound with predicted characteristics. Inactive disposal mounds were also stable and require no special monitoring with the exception of MQR which should be monitored in 1992. The sediment chemistry at the three reference sites and dissolved oxygen levels are consistent with conditions in central Long Island Sound. The June 1991 monitoring cruise at CLIS was designed to delineate the areal extent of the dredged material and to assess possible environmental impact of past and recent disposal by monitoring the recolonization status of the resident infaunal community. The dredged material did form the distinct mound predicted at the CLIS-90 buoy location. The radius of the mound detected acoustically was not as large as predicted. At CS-90-1, the additional cap material added to the existing mound, and two areas of 20 cm thick material were detected acoustically. The detection of dredged material by REMOTS® photographs increased the observed areal extent of “fresh” dredged material beyond that measured acoustically. However, the dredged material footprint associated with the CLIS-90 mound was difficult to distinguish from older dredged material. Material from disposal activity over the last five years overlaps and makes it difficult to distinguish "fresh" dredged material. Both the bathymetry and REMOTS® map of fresh dredged material supported the prediction that the CLIS-90 buoy mound would be within a radius of 200 to 250 m. Stage I seres dominated the CLIS-90 buoy mound and the CS-90-1 mound as predicted. Stage III seres dominated the inactive FVP, NHAV-74, CLIS-88, and CLIS-89 mounds as predicted for normal colonization. These data indicate that no further special chemical or physical monitoring is required at these mounds at this time. The MQR inactive mound had four Stations with Stage I taxa, and shallow RPD depths were measured around the mound center. Stations E5 and D7, south and west of CLIS-89, were azoic or had low OSI values with evidence of trawling. These areas, MQR, E5, and D7, should be reevaluated in 1992. Dissolved oxygen levels in the bottom water, and metals and PAH baseline levels in the sediments, were measured at CLIS and the three reference areas to assess environmental quality. The DO levels at CLIS were spatially homogenous between reference areas and the disposal site, showing no hypoxia and varying between 6.3 and 6.77 mg-I’'. Results of the metal analyses indicate relatively low levels of Cd, Pb, and Zn, consistent with previous measurements. —————— I Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 51 PAH compounds were present at all three reference areas. Normalized concentrations of total LMW and HMW PAHs were between concentrations measured at two central Long Island Sound sites (Eastern and Western). Future monitoring at the CLIS reference areas should include PAH sampling to compare with this baseline data to see whether the concentrations of PAHs vary over time. Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 52 6.0 REFERENCES Forstner, U.; Wittman, C. T. W. 1983. Metal pollution in the aquatic environment. 2nd ed. New York: Springer-Verlag. Germano, J. D.; Parker, J.; Wiley, M. B. 1993. Monitoring cruise at the Central Long Island Sound Disposal Site, July 1990. SAIC Report No. SAIC-90/7594&C89. Final report submitted to US Army Corps of Engineers, New England Division, Waltham, MA. Goldring, R. 1964. Trace fossils and the sedimentary surface in shallow water marine sediments. In: van Straaten, L.M.J.U., ed. Deltaic and Shallow Marine Deposits. Developments in Sedimentology, v. 1, pp. 136-143. Kennish, M. J. 1992. Ecology of estuaries: anthropogenic effects. Boca Raton, FL: CRC Press, Inc. Kranz, P. 1974. The anastrophic burial of bivalves and its paleontological significance. Jour. Geol. 82: 237-265. McGroddy, S. E.; Farrington, J. W.; Phinney, C. S.; Johnson, C. G. 1992. Partitioning of polycyclic aromatic hydrocarbons between sediments and porewaters from Boston Harbor, Mass. Seventh Annual Boston Harbor/Mass. Bays Symposium Proceeding, Mass. Bay Marine Studies Consortium, P.O. Box 660, Boston, MA 02125-0005 (Abstract). NOAA. 1991. Second summary of data on chemical contaminants in sediments from the National Status and Trends Program. NOAA Tech. Mem. NOS OMA 59. National Oceanographic and Atmospheric Administration, Rockville, MD. Oceanic Society. 1982. Dredging and dredged material management in the Long Island Sound Region. Stamford, CT: The Oceanic Society. New England Governors Conference, Boston, MA. Parsons, T. R.; Maita, Y.; Lalli, C. M. 1984. A manual of chemical and biological methods for seawater analysis. New York: Pergamon Press. Pequegnat, W. E.; Galloway, B. J.; Wright, T. D. 1990. Revised procedural guide for designation surveys of ocean dredged material disposal sites. Final Report. Technical Report D-90-8. Prepared for the Department of the Army, US Army Corps of Engineers, Washington, D.C. Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 53 Rhoads, D. C.; Germano, J. D. 1986. Interpreting long-term changes in benthic community structure: a new protocol. Hydrobiol. 142: 291-308. SAIC. 1985. Standard operating procedure manual for DAMOS monitoring activities. DAMOS Contribution No. 48 (SAIC Report No. SAIC-85/7516&C48). US Army Corps of Engineers, New England Division, Waltham, MA. SAIC. 1989. Monitoring surveys at the New London Disposal Site, August 1985 - July 1986. DAMOS Contribution No. 60 (SAIC Report No. SAIC-86/7540&C60). US Army Corps of Engineers, New England Division, Waltham, MA. SAIC. 1990. Monitoring cruise at the Central Long Island Sound Disposal Site, July 1988. DAMOS Contribution No. 72 (SAIC Report No. SAIC-88/7548&C75). US Army Corps of Engineers, New England Division, Waltham, MA. Strickland, J. D. H.; Parsons, T. R. 1972. A practical handbook of seawater analysis. Fish. Res. Can. Bull., 167 pp. Tavolaro, J. F. 1984. Sediment budget study for clamshell dredging and ocean disposal activities in the New York Bight. Environ. Geol. Water Sci. 63: 133-140. Tyson, R. V.; Pearson, T. H. 1991. Modern and ancient continental shelf anoxia: an overview. In: Tyson, R. V.; Pearson, T. H., eds. Modern and Ancient Continental Shelf Anoxia. Geol. Soc. of London, Sp. Pub., 58, pp. 1-24. Monitoring Cruise at the Central Long Island Sound Disposal Site, June 1991 aerobic 48 anoxia 53 atomic absorption spectrophotometry 9 azoic 27, 50 barge vi, 41, 43 barges vii, 1, 41, 43 benthos vi, vii, 1, 2, 5, 10, 27, 41, 43, 44, 48-50, 53 bivalve 52 epi- 49 macro- 48 bioturbation 21, 41, 44 feeding void 43 foraging 27 Black Rock Harbor 44 boundary roughness v, vi, 21, 41 buoy vii, 1, 2, 5, 11, 21, 38, 41, 48, 50 disposal vii, 11, 41 capping 1, 11 Central Long Island Sound (CLIS) 1, iv, V, vi, vii, 1-3, Se LOPS aay: ON DI32. 33,34: 38, 40, 41, 43, 44, 45, 47, 48, 50, 52, 53 Capsite-1 (CS-1) vii, 1, 5, 17, 21, 27, 43 JENAR sab, Ilesys JU Pall, Alls 32, 43, 50 MOR villas. 1227: 32, 44, 50 colonization 50 conductivity 1 contaminant 10, 44, 45, 47, 52 CTD meter vii, 1, 5, 10, 38, 48 currents 21 density sigma-t vil deposition 21, 47 dispersion 1 disposal site Central Long Island Sound (CLIS) 1, iv, v, vi, Vil l=3 5a oO» Wile, Sys 1i/, Zs PATE, 32, 33, 34, 38, 40, 41, 43-45, 47, 48, 508522993 New London iv, 45, 53 Western Long Island Sound (WLIS) iv, 45, 48 dissolved oxygen iv, vii, 1, 2, 10, 27, 38, 40, 41, 48, 49, 50 dredging clamshell 53 erosion 21, 27 feeding void 43 fish 47, 53 grain size iv, v, 1, 7, 9, 11, 17, 32, 33, 44, 45, 47, 48 habitat 27, 47, 48 hypoxia 27, 48, 50 interstitial water 43 methane 17, 27 organics polyaromatic hydrocarbon (PAH) iv, vii, 1, 2, 7, 9, 10, 38, 44, 47, 48, 50, 51 total organic carbon 1, 7, 9, 32, 33 oxidation 48 recolonization vii, 2, 5, 21, 43, 50 reference area vi, 5, 7, 17, 38, 44, 45, 47 reference station iv, vi, 40, 43, 44, 50 CLIS-REF 5, 7, 10, 17, 32, 33, 34, 38, 40, 44 REMOTS® boundary roughness _v, vi, 21, 41 Organism-Sediment Index (OSI) 27, 32, 50 redox potential discontinuity (RPD) vii, 21, 41 REMOTS® jy, vii, 1, 5, 7, 10, 11, PA, PA REPRO 43, 50 RPD REMOTS®;redox potential discontinuity (RPD) Ae wath, Ils Palle Il, 44, 50 RPDs REMOTSS®;redox potential discontinuity (RPD) 21, 41 salinity vii, 2, 10, 38 sandy 47 sediment chemistry 41, 44, 50 clay72.1 b, li7,-32, 33,744. 45, 47 gravel 7 Sand e717 -32..35 silt. 7, .115°17,:32, 33,,44, 45, 47 sediment oxygen demand (SOD) 44 sediment sampling 1, 7 cores 7 grabs vii, 7 shore station 5 sigma-t vii species dominance 17 spectrophotometry atomic absorption 9 statistical testing Mann-Whitney U-test 21, Pas Bye succession INDEX (cont.) seres vii, 43, 44, 50 successional stage vi, 27, 43 survey baseline vii, 2, 44, 50, 51 bathymetry v, vii, 1, 5, 10, 11, 15, 41, 43, 50 postdisposal 1 REMOTS® 5, 17, 21, 27, 32) temperature vii, 1, 2, 10, 38 tide 5 topography 1, 41 toxicity 47 trace metals iv, vii, 7, 9, 10, 32, 34, 38, 44, 45, 47, 50, 52 cadmium (Cd) 7, 9, 32-34, 38, 44, 48, 50 magnesium (Mg) 40, 49, 50 zinc (Zn) 7, 9, 32-34, 44, 50 trawling 32, 44, 50 volume estimate 43 Appendix Depth (meters) CLIS-91 Oxygen (ppm) xxxx 6 vy, Depth (meters) CLIS-91 SI@lamMel= ararses 18 Ie 20 Salinity (ppt) **«« 26 2, 28 Temperature (C) xxxx 15 16 17 18 19 Depth (meters) 2500W-REF Oxygen (ppm) xxxx 7 8 Depth (meters) 2500W-REF sigma—t ++++ 18 19 20 Salinity (ppt) **«« 26 27) 28 Temperature (C) xxxx 12 16 We Ws) WS) Depth (meters) CLIS-91 4500E-REF Oxygen (ppm) xxxx 6 7 5 8 9 O a ee a 5 x * x ee ; x 10 x i i : x % 20 . TES) 50) Depth (meters) CLIS-91 4500E-REF Sigma-t ++++ 17 18 19 20 21 (ANE CH on el ese) Salinity (ppt) **** 26 27 28 29 Temperature (C) xxxx asave) cabo 16 NY, 18 19 20 x at : iy i ii 15 x ae: ¥ sat ti 20 | hi 29 S10) CLIS-REF Oxygen (ppm) xxxx U 6 (Suajaw) ujdaq Depth (meters) CLIS-REF sigma-t ++++ Salinity (ppt) ***« 26 DY Temperature (C) xxxx 14 15 16 17 18 19 20