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A Sediment Testing Reference Area Database for the San Francisco Deep Ocean Disposal Site (SF-DODS)

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Background on Testing Sediment for SF-DODS Disposal

Figure 1. This map shows the route of a typical disposal vessel trip to the SF-DODS. The vessel remains within the established shipping lanes in the vicinity of the Farallon Islands as required.Figure 1. This map shows the route of a typical disposal vessel trip to the SF-DODS. The vessel remains within the established shipping lanes in the vicinity of the Farallon Islands as required. | Click the image to enlargeThe San Francisco Deep Ocean Disposal Site (SF-DODS) is the deepest ocean dredged material disposal site in the United States. It is located off the Continental Shelf in approximately 8,200 to 9,800 feet (2,500 to 3,000 meters) of water, approximately 55 nautical miles (100 kilometers) offshore of San Francisco (Figure 1).

In order for U.S. Army Corps of Engineers (USACE) to authorize a permit for the disposal of dredged material at the SF-DODS, sediment evaluations (as described in the national testing manual, the Ocean Testing Manual) must first be conducted on the dredged material proposed for ocean disposal. EPA and USACE can determine suitability of dredged material for ocean disposal by comparing the test results of the proposed dredged material against the test results of a designated reference sediment. EPA identifies reference sediments as substantially free of contaminants and as representative as possible of what conditions at the disposal site would be if no dredged material had ever been disposed there.

The reference area identified by EPA for the SF-DODS is located in approximately 4,200 feet (1,285 meters) of water, at 37°25.00' N and 123°14.90' W (NAD 83). This site is approximately 20 nautical miles (35 kilometers) from the SF-DODS itself (Figure 1).

SF-DODS Disposal AreaSF-DODS Disposal AreaJust as the SF-DODS is the nation's deepest disposal site, its reference area is the deepest as well. The great water depth and open-ocean location of the reference site make the collection of its sediment very expensive and logistically difficult. Weather and sea-state conditions can force costly delays in project sampling programs and, in extreme conditions, can present a concern for human safety. For these reasons, EPA believes it is appropriate to establish and maintain a reference area database of previously-collected sediment test results that may be used in lieu of collecting and testing the reference area's sediment directly.

EPA anticipates that project proponents will typically elect to compare their test result against the appropriate values in the database when timing, cost or safety considerations present significant obstacles in collecting new reference site sediment. However, any project proponent may propose to compare their sediment test result against the most current sediment test results in the reference area database.

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The Reference Area Database

Several sets of sediment test data have been successfully collected from the SF-DODS reference area since 1990. Physical, chemical and biological data from these studies are summarized in Tables 1 through 4.

  • Table 1 depicts the range of bulk sediment chemistry values found at the reference site for all typical contaminants of concern.
  • Table 2 shows solid phase acute toxicity bioassay results for two species of amphipods and two species of polychaetes.
  • Tissue chemistry results are provided for all typical bioaccumulative contaminants of concern, for one clam species in Table 3, and two polychaete species in Table 4.

(Suspended particulate phase bioassays are not included in the database, since results from these tests are compared against water quality criteria as opposed to reference sediments.) Thus, all types of reference sediment data necessary for full Tier III OTM evaluations are included in the database.

Cautions for Project Proponents about Using the Reference Area Database

If you choose to compare your dredged material test data against the SF-DODS reference area database, you must use the same test species reflected in the database. You should use caution when comparing to the reference area database values, as this can result in disposal suitability determinations by EPA and the USACE that are slightly more conservative (more environmentally protective) than would be the case if the reference sediments were tested directly.

This is because, in this approach, you are directly (not statistically) comparing to the reference area database values. Therefore, when average amphipod mortality in a sediment sample is more than 20 percent above the overall average value in the reference area database, the test sediment is automatically considered unsuitable for ocean disposal. This will be true even if the test sediment and reference area sediment might not have been statistically different if they had been tested directly at the same time.

In the same manner, when polychaete mortality is more than 10 percent above the corresponding overall average value in the reference area database, it is considered unsuitable for ocean disposal.

Comparison of bioaccumulation test results to the reference area database also will be made directly, as opposed to statistically. For bioaccumulation data, EPA will evaluate test data generally against the range of tissue concentrations in the reference area database, as well as consider available published scientific information concerning tissue residue effects.

Before starting any sediment testing program that supports proposed ocean dumping at SF-DODS, you should work with the Region 9 EPA Dredging and Sediment Management Team to develop a draft Sampling and Analysis Plan. The Region 9 team must approve the Plan.

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Tables of Physical, Chemical and Biological Data Collected from SF-DODS Reference Area

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Parameter Results from Seperate Assessments   Overall Range
Table 1a. Sediment Chemistry for the SF-DODS Reference Area: Conventionals
Grain Size (%)                
sand/gravel 34 60 59 45 16 37 39 16-60
silt 45 27 25 35 62 39 44 25-62
clay 21 13 16 20 22 24 17 13-24
Total Organic Carbon (%) 1.35 0.63 0.74 0.79 1.44 1.45 1.8 0.63-1.45
Total Volatile Solids (%) 2.49 4.28 4.38 2.34 5.74 N/A N/A 2.34-5.74
TRPH (ppm dw) nd<29 6.7 nd<16 nd<16 17.1 1.8 nd>2.0 nd-17.1

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Parameter Results from Seperate Assessments (ppm dw)   Overall Range (ppm dw)
 
Table 1b. Sediment Chemistry for the SF-DODS Reference Area: Trace Metals
Arsenic 2.2 3.9 4.25 5.33 4.0 2.6 nd nd-5.33
Cadmium 0.5 0.3 0.3 0.4 0.6 0.3 nd nd-0.6
Chromium 171 225 247 197 172 283 69.2 69.2-283
Copper 23.5 20.3 21.8 21.8 30.7 86.3 18.3 18.3-86.3
Lead 10.8 9.1 6.8 8.2 9.2 26 5.1 5.1-26
Mercury 0.1 0.2 0.1 0.1 0.2 0.1 0.1 0.1-0.2
Nickel 68.1 63.5 70.0 69.4 82.8 238.0 50.9 50.9-238
Selenium 1.3 0.6 1.2 0.8 2.6 0.7 1.5 0.6-2.6
Silver 0.6 0.2 0.4 0.3 0.5 1.0 0.4 0.2- 1.0
Zinc 84.3 82.5 82.3 76.3 91.0 288.0 60.8 60.8-288

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Parameter Results from Seperate Assessments ppb dw)   Overall Range (ppb dw)
 
Table 1c. Sediment Chemistry for the SF-DODS Reference Area: Organics
Total LPAH (a) 48 11 14 65 77 nd nd nd-77
Total HPAH (b) 68 6 23 57 115 nd 31 nd-115
Total PAHs 116 17 37 122 192 nd 31 nd-192
Total PCB (c) nd nd nd nd nd nd nd nd
Total Butyltins (d) nd nd nd nd nd 1.3 nd nd-1.3

NOTE:

  1. Reported as total of 6 LPAHs: naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene
  2. Reported as total of 9 HPAHs:fluoranthene, pyrene, benzo(a)anthracene, chrysene, Benzo(b,k)fluoranthene, benzo(a)pyrene, dibenzo(a,h)anthracene, benzo(g,h,i)perylene, indeno(1,2,3-c,d)pyrene
  3. Reported as total of Aroclor equivalents 1242, 1248, 1254, and 1260
  4. Reported as total of Mono-, Di-, and Tri- and Tetrabutyltin

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Parameter Results from Seperate Assessments (ppb dw)   Overall Range (ppb dw)
 
Table 1d. Sediment Chemistry for the SF-DODS Reference Area: Chlorinated Organic Pesticides
Aldrin nd nd nd nd nd nd nd nd
Dieldrin nd nd nd nd nd nd nd nd
Chlordane nd nd nd nd nd nd nd nd
DDE/DDD/DDT nd nd nd 1.2 nd nd 2.1 nd-2.1
Endosulfan I nd nd nd nd nd nd nd nd
Endosulfan II nd nd nd nd nd nd nd nd
Endosulfan Sulfate nd nd nd nd nd nd nd nd
Endrin nd nd nd nd nd nd nd nd
Heptachlor nd nd nd nd nd nd nd nd
Heptachlor Epoxide nd nd nd nd nd nd nd nd
Alpha- BHC nd nd nd nd nd nd nd nd
Beta- BHC nd nd nd nd nd nd nd nd
Delta- BHC nd nd nd nd nd nd nd nd
Gamma- BHC nd nd nd nd nd nd nd nd
Toxaphene nd nd nd nd nd nd nd nd

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Species Average Survival in Separate Bioassays (percent) Overall Average Survival (a)
 
Table 2. Percent Survival in Toxicity Bioassays of SF-DODS Reference Area Sediments
Amphipods              
Rhepoxinius abronius 89 94 86 97 83   89.8 (n=5)
Ampelisca abdita 92 98 88       90.5 (n=3)
Polychaetes              
Nephyts caecoides 96 99 93 97 95 92.5 95.4 (n=6)
Neanthes arenaceodentata 96 100         98.0 (n=2)

NOTE:

  1. Direct (not statistical) comparison is made between these values and test sediment average survival results.

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Parameter Results from Seperate Bioassays (ppm ww) Overall Range (ppm ww)
 
Table 3a. Tissue Chemistry for the Clam Macoma nasuta Exposed to SF-DODS Reference Area Sediments: Trace Metals
Arsenic 2.3-4.0 2.8-4.0 2.4-3.0 3.3-3.7 3.0-3.9 2.2-2.5 2.2-4.0
Cadmium nd-0.03 0.03-0.05 0.01-0.04 0.03-0.05 0.02-0.04 0.01-0.02 nd-0.05
Chromium 0.2-0.4 0.3-0.6 0.3-0.4 0.2-0.3 0.3-0.5 0.4-0.5 0.2-0.6
Copper 1.2-2.5 2.1-8.7 1.8-2.9 1.4-2.0 1.6-2.0 2.3-3.1 1.2-8.7
Lead 0.1-0.2 0.1-0.8 0.1-0.2 0.1 0.1-0.2 0.1-0.3 0.1-0.8
Mercury 0.01 0.01-0.02 0.01 0.01 0.01 0.1 0.01-0.1
Nickel 0.5-0.8 0.6-4.3 0.4-0.5 0.5-0.7 0.6-0.9 0.2-1.0 0.2-4.3
Selenium 0.2-0.3 0.3-0.4 0.2 0.2-0.4 0.2-0.3 0.3 0.2-0.4
Silver 0.02-0.06 0.06-0.26 0.05-0.1 0.03-0.04 0.02-0.12 0.1 0.02-0.26
Zinc 11.0-14.0 13.6-18.2 12.6-16.6 8.8-13.6 9.0-14.0 15.0-18.0 8.8-18.2

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Parameter Results from Seperate Bioassays (ppb ww) Overall Range (ppb ww)
 
Table 3b. Tissue Chemistry for the Clam Macoma nasuta Exposed to SF-DODS Reference Area Sediments: Organics
Total LPAH (a) 2-3 nd 1-2 6-10 2-5 nd nd-10
Total HPAH (b) 12-17 nd-26 3-8 21-25 2-7 nd<40 nd-26
Total PAHs 12-17 nd-26 4-9 27-33 4-11 nd<40 nd-33
Total PCB (c) nd<20 nd<20 2.6-4.2 nd 2.5-3.5 nd<20 nd-4.2
Total Butyltins (d) 1.7-3.6 3.1-10.2 2.2-3.4 nd-1.6 4.0-11.0 N/A nd-11.0

NOTE:

  1. Reported as total of 6 LPAHs: naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene
  2. Reported as total of 9 HPAHs:fluoranthene, pyrene, benzo(a)anthracene, chrysene, Benzo(b,k)fluoranthene, benzo(a)pyrene, dibenzo(a,h)anthracene, benzo(g,h,i)perylene, indeno(1,2,3-c,d)pyrene
  3. Reported as total of Aroclor equivalents 1242, 1248, 1254, and 1260
  4. Reported as total of Mono-, Di-, and Tri- and Tetrabutyltin

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Parameter Results from Bioassays (ppb ww) Overall Range (ppb ww)
 
Table 3c. Tissue Chemistry for the Clam Macoma nasuta Exposed to SF-DODS Reference Area Sediments: Chlorinated Organic Pesticides
Aldrin nd nd 0.7 nd nd nd nd-0.7
Dieldrin nd nd nd nd nd nd nd
Chlordane nd nd nd nd nd nd nd
DDE/DDD/DDT nd nd 0.9 1.4-1.8 0.4-0.6 nd nd-1.8
Endosulfan I nd nd nd nd nd nd nd
Endosulfan II nd nd nd nd nd nd nd
Endosulfan Sulfate nd nd nd nd nd nd nd
Endrin nd nd nd nd nd nd nd
Heptachlor nd nd 0.18 nd nd nd nd-0.18
Heptachlor Epoxide nd nd nd nd nd nd nd
Alpha- BHC nd nd 0.1-0.4 nd 0.2 nd nd-0.4
Beta- BHC nd nd nd nd nd nd nd
Delta- BHC nd nd nd nd nd nd nd
Gamma- BHC 0.13 nd nd nd nd N/A nd-0.13
Toxaphene nd nd<100 nd nd nd nd nd

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Parameter Results from Seperate Bioassays (ppm ww) Overall Range (ppm ww)
 
Table 4a. Tissue Chemistry for Two Polychaete Species Exposed to SF-DODS Reference Area Sediments: Trace Metals
  Nereis Nephtys Nephtys Nephtys Nephtys Nephtys (Nephtys only)
Arsenic 2.0-2.3 2.7-2.9 3.3-3.9 2.7-3.1 2.9-4.9 1.4-2.4 1.4-4.9
Cadmium 0.05-0.06 0.3 0.2-0.3 0.1 0.1-0.2 0.03-0.1 0.03-0.3
Chromium 0.1-0.2 0.03-0.04 0.1-0.2 0.1 0.1-0.25 0.3-0.4 0.03-0.4
Copper 1.3-1.7 1.8 0.8-1.9 1.0-1.7 1.7-2.2 1.7-2.2 0.8-2.2
Lead 0.1 0.1 0.1 0.02-0.1 0.1 0.1-0.3 0.02-0.3
Mercury 0.02-0.04 0.01-0.1 0.01 0.01-0.02 0.01 0.1 0.01-0.1
Nickel 0.2-0.3 0.7 0.3-0.5 0.2-0.6 0.5-1.2 0.4-0.8 0.2-1.2
Selenium 0.2-0.3 0.3 0.3-0.6 0.2-0.3 0.2-0.4 0.3-0.4 0.2-0.6
Silver 0.03-0.08 0.01 0.01-0.02 0.01 0.01 0.1-0.2 0.01-0.2
Zinc 10-34 27-29 29-34 22-26 28-33 12-30 10-34

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Parameter Results from Seperate Bioassays (ppb ww) Overall Range (ppb ww)
 
Table 4b. Tissue Chemistry for Two Polychaete Species Exposed to SF-DODS Reference Area Sediments: Organics
  Nereis Nephtys Nephtys Nephtys Nephtys Nephtys (Nephtys only)
Total LPAH (a) 4-11 nd 4-13 1-3 5-11.6 nd nd-13
Total HPAH (b) 17-25 nd 2-3 nd-1 4-9.5 nd nd-9.5
Total PAHs >21-36 >nd >6-16 >2-4 >9-18 nd nd-18
Total PCB (c) nd nd nd nd nd nd nd
Total Butyltins (d) 2.7 nd-9.3 5.2-206 nd 30-40 N/A nd-206

NOTE:

  1. Reported as total of 6 LPAHs: naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene
  2. Reported as total of 9 HPAHs:fluoranthene, pyrene, benzo(a)anthracene, chrysene, Benzo(b,k)fluoranthene, benzo(a)pyrene, dibenzo(a,h)anthracene, benzo(g,h,i)perylene, indeno(1,2,3-c,d)pyrene
  3. Reported as total of Aroclor equivalents 1242, 1248, 1254, and 1260
  4. Reported as total of Mono-, Di-, and Tri- and Tetrabutyltin

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Parameter Results from Bioassays (ppb ww) Overall Range (ppb ww)
 
Table 4c. issue Chemistry for Two Polychaete Species Exposed to SF-DODS Reference Area Sediments: Chlorinated Organic Pesticides
  Nereis Nephtys Nephtys Nephtys Nephtys Nephtys (Nephtys only)
Aldrin nd nd nd nd nd nd nd
Dieldrin 0.72 nd nd nd nd nd nd-0.72
Chlordane nd nd nd nd nd nd nd
DDE/DDD/DDT nd nd 0.5-4.4 nd nd nd nd-4.4
Endosulfan I nd nd nd nd nd nd nd
Endosulfan II nd nd nd nd nd nd nd
Endosulfan Sulfate nd nd nd nd nd nd nd
Endrin nd nd nd nd nd nd nd
Heptachlor nd nd nd nd nd nd nd
Heptachlor Epoxide nd nd nd nd nd nd nd
Alpha- BHC nd nd 0.1-1.9 nd nd nd nd-1.9
Beta- BHC nd nd nd nd nd nd nd
Delta- BHC nd nd nd nd nd nd nd
Gamma- BHC nd nd nd nd nd N/A nd
Toxaphene nd nd nd nd nd nd nd

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