UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION 4 ATLANTA FEDERAL CENTER 61 FORSYTH STREET ATLANTA, GEORGIA 30303-8960

May 10, 2010

New Jacksonville ODMDS Designation Dive Report
Dates: 3/31/10 Divers: Drew Kendall (Dive Master, EPA Regi on 4); Chris McArthur (EPA Region 4); Nadia Lombardero (ANAMAR Environmental Consulting) Water Temp: ~60F Purpose: To ground-truth sidescan sonar data to determine bottom type.

Dive #1
Date: 3/31/10
Time: 1308
Duration: 24min Depth: 63’
Location: DS2 Divers: NL, CM Buoy Location at end of dive: 30 19.706’N; 81 17.138’W Description: Dive may have been off target by 80 to 100 feet based on measurement of the buoy at the end of the dive. Visibility wa s very poor (1-2 feet) with moderate bottom
current. Was able to see the bottom with use of video camera lights. Bottom consisted of waves in a very fine sand intermingled with patches of silt at the bottom. Silt appeared to be approximately 3 inches thick over sand. Observed one sea star and numerous worm
tubes.

Dive #2
Date: 3/31/10
Time: 1404
Duration: 12min Depth: 56’
Location: DS4 Divers: DK, CM Buoy Location at end of dive: 30 19.755’N; 81 16.936’W Description: Poor visibility. Bottom appeared to be coarse sand bottom with some shells.

Dive #3
Date: 3/31/10
Time: 1458
Duration: 19min Depth: 60’
Location: DS7Divers: CM, NL Description: Very poor visibility, worst visi bility of the 3 dives performed today. Anchor landed on rock outcrop. Rocks appeared to be fi xed in place and ledge like (flat and quite large, did not move when pushed, but they also seemed jagged in nature). Could not
determine if the area was a natural or artifici al reef.. Change in elevation (2 feet) at rockface with upper surface consisting of a very fine and soft silt (about 2 -3 inches covering either more rocks or hard bottom. P hotos taken. Very poor visibility (1 foot) and moderate current at the bottom, surge-li ke in nature. Circular pattern search was attempted but not conducted due to conditions, instead a short (about 5 meter) transect was done. A portion of the transect encounter ed the rock outcrop described above and the next perpendicular 5 meter transect had a 1⁄2 foot layer of very, very soft fine silt (pudding like) over loose medium coarse sand. No rocks were observed on the second 5
meter transect. The fine silt seemed to be agitated by the bottom surge creating an
“underwater cloud” that affected the visibility even further.

Figure 1: Growth on Rocks at DS7 Figure 2: Growth on Rocks at DS7

Dive #4
Date: 4/1/10
Time: 1218
Duration: 22min Depth: 63’
Location: DS1 Buoy Start Position: 30 18.542; 81 16.020’W Buoy End Position: 30 18.528’N; 81 16.025’W Divers: NL, CM Description: Decent visibility (4 feet). A semicircle with radius of 25 feet was conducted to the west of the buoy. Areas of dense polychaetes were encountered. Bottom was a mixture of grey sand, gray sand with shells, gray sand with tube worms, and sandy areas with a thin transient layer of brownish silt intermixed with the sand. A limited amount of
video was obtained in this area. The vide o shows a transition zone between fine sand with some small shell fragments mixed in a nd a thicker silt area that when disturbed dissolved readily in the water column thus creating poor visibility. The consistency of the silt was like “pudding”. Some of the si lt areas had settled creating small balls and
some relief which is evident on the video. The area with the “ pudding balls” relief wasabout 6 inches deep. Two samples were take n, one of the gray sand material and one of the very fine silt.

Figure 3: Sandy bottom at DS1 Fi gure 4: Lumpy clay bottom at DS1

Figure 5: Polychaete covered bottom at DS1 Figure 6: Matted bottom at DS3

Dive: #5
Date: 4/1/10
Time: 1319
Duration: 20min Depth: 59’
Location: DS3 Buoy Start Location: 30 17.700’; 81 81 17.830’W Buoy End Location: Not Recorded Divers: DK, CM Description: Moderate Visibility (3 feet). Sandy bottom was encounter ed with very thick mats of organisms including bivalves. The thick mats occurred as mounds as high as 6 inches above the surrounding sandy bottom. One sample was taken. One theory is that the mats are Caulerpas rhizome holdfasts.Dive #6
Date: 4/1/10
Time: 1406
Duration: 25min Depth: 62’
Location: DS5 Buoy Start Location: 30 18.795’N; 81 17.055’W Buoy End Location: 30 18.787’N; 81 17.052’W Divers: NL, CM Description: Poor Visibility (2 feet). Three quarters of a 50 foot circle starting from the north of the buoy was conducted. Th e first half of the circle consisted of a sandy bottom with limited polychaetes. Starfish and sea st ars were also observed. The last quadrant consisted of the same very fine silt that wa s encountered in DS1, it was easily stirred up upon contact. Did not see the same type of relieve or depth of the silty material as encountered on DS1, but a much finer “v eneer” layer up to 3 inches deep.

Figure 7: Bottom at DS7Sidescan Sonar Record

DS4