S-EPA
Palos Verdes Shelf
Superfund Site
U.S. Environmental Protection Agency • Region 9 • San Francisco, CA • February 2008
Remedial Investigation Report Completed;
Feasibility Study Underway
, Point Conception
ngeles
Fortuj
Lands
Ft. Vicente
Harbor
White Point
Pt. Fermin
The Palos Verdes Shelf Superfund site is an area of con-
taminated sediment off the Palos Verdes Peninsula. The
contaminated sediment lies in the Pacific Ocean at depths of
150 ft. and more, too deep for human contact. However, the
fish found in the Palos Verdes Shelf area contain high con-
centrations of DDT and PCBs. Although current concentra-
tions have dropped from historical highs, concentrations of DDT and
PCBs in fish continue to pose a threat to human health and the natu-
ral environment.
For a copy of this fact sheet, visit www.pvfish.org or call Toll Free 1-800-231-3075.
Para obtener una copia en espaiiol de esta hoja informativa, visite la pagina Web al:
www.pvsfish.org o llame a la linea gratuita al 1 800 231-3075.
, MI5 www.pvsfish.org ,	1 800 231-3075o
Qu^ vi c6 the xem ban Tieng Vi?t ciia ciia ban dft ki$n nay t$i trang web www.pvsfish.org ho£c
yeu c&u qua s6 difn thoai Miln Phi 1 800 231-3075.
Remedial
Investigation Report
At-A-G lance
Palos Verdes Peninsula
Figure 1:
Palos Verdes
Superfund
Study Area
Southern
California Bight
Southern California
Santa Monica
Bay
LOS ANGELES
COUNTY
The Remedial Investigation (Rl) summa-
rizes:
•	the nature and extent of
contamination,
•	the transport and fate of the
contamination
•	current risk to human health and the
environment from the site.
Although discharge of DDT and PCBs
stopped over 30 years ago, these persistent
pollutants remain in the sediment off Palos
Verdes Peninsula. The Rl found the quantity
of DDT and PCBs has dropped over the
years. Some of the contaminants have been
carried off the shelf into deeper waters, some
have been diluted by mixing with cleaner
sediment, and within the contaminated sedi-
ment deposit we found evidence that DDT—
but not PCBs—is slowly breaking down. The
Rl report used new fish data to recalculate
the risk to human health posed by the site
and found that fish, especially bottom-feed-
ers like white croaker, still contain levels of
DDT and PCBs that warrant fish advisories
(see Table 1, Pg. 7). The site still poses a
threat to wildlife in the area as well, although
we have seen some indications of recovery,
like bald eagles nesting on the Channel Is-
lands.

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EPA has been addressing the immediate threat to human
health by working with state and local agencies as well as
community groups to reduce consumption of fish species
most likely to contain high concentrations of contaminants.
The Institutional Controls program is described on Page 4.
Concurrently, EPA began the Superfund process of investi-
gation, risk assessment, and remedy selection.
This fact sheet summarizes EPA's Remedial Investigation
(RI) Report that presents our current understanding of con-
ditions in the Palos Verdes Shelf Study Area. The full RI
Report for the Palos Verdes Shelf Superfund Site is avail-
able online at EPA's Region 9 website:
www. epa. gov/region09/waste/ sfund/pvshelf.
Following the RI, EPA will formulate potential remedies to
reduce the risk to human health and the environment posed
by the site. These alternative remedial actions will be de-
scribed in a Feasibility Study, scheduled to be released for
public reviewin Fall 2008. EPA will describe its preferred
alternative in a proposed plan that will be available for com-
ment at public meetings in the San Pedro/Palos Verdes
Peninsula vicinity.
Site Characteristics
The California coast from Pt. Conception to the Mexican
border curves inward, forming a large bay called the
"Southern CaliforniaBight." The Palos Verdes Peninsula
is a small but prominent land mass extending into the South-
ern California Bight. It is bordered by Santa Monica Bay to
the north and the San Pedro Shelf to the south. The Chan-
nel Islands lie to the west and northwest. The narrow un-
derwater shelf off the Palos Verdes Peninsula is called the
Palos Verdes Shelf. It is approximately 9 miles long and
less than 1 Vi miles wide. The seabed over most of the shelf
slopes at a gentle 1 to 3 degrees. The shelf breaks at a
depth of 250 to 300 feet, then drops steeply over 2,300 feet
to the ocean floor. (See Figure 1.)
A193 3 study of the Palos Verdes Shelf characterized it as
an area of rocky outcrops and kelp beds. Since then, ur-
banization, the Portuguese Bend Landslide, and the White
Point outfalls have changed that. From the 1930s through
the 1980s, the White Point outfalls have discharged onto the
shelf about 4 million tons of sediment. North of the outfalls,
the Portuguese Bend Landslide has contributed an esti-
mated 6 to 9 million tons of sediment onto the shelf since
the 1950s. Engineering measures have stabilized the land-
slide; nevertheless, the toe of the landslide continues to
erode and act as a source of sediment.
The current and wave patterns along the Palos Verdes
Shelf vary by season and location. Figure 2 shows the
general flowpatterns for the Southern CaliforniaBight.
Dominant ocean circulation patterns include the southward-
flowing California Current, the northward-flowing California
Counter current, and seasonal influences
by the northward-trending Davidson
Counter current. Surface and bottom
waters are typically separated in spring
through fall by a pycnocline (a zone of
rapid change in seawater density) occur-
ring at depths of 3 0 to 100 ft. Currents
below the pycnocline on the shelf gener-
ally flow to the northwest, parallel to
seabed contours. In contrast, surface
currents flow predominantly southeast-
ward, although they shift to a westerly
flow in late autumn and early winter
when westerly winds weaken. Most of
the time, near-bottom waves and cur-
rents do not resuspend sediment; how-
ever, episodically, primarily during
storms, currents and waves resuspend
and move sediment across and off the
shelf.
Santa
Monica
SANTA BARBARA
Pt Dome
fedro x Newport
Beach
California
Countercurrent
Caiiforni
Current
System
46048
Figure 2: General flow patterns for the Southern California Bight
Page 2
Palos Verdes Shelf Superfund Site

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Why are there tons of DDT and
PCBs on Palos Verdes Shelf?
Los Angeles County wastewater (effluent) has discharged
at White Point off the Palos Verdes Shelf since 193 7. Sew-
age is treated at the Joint Water Pollution Control Plant in
the City of Carson before it enters the outfalls. The Los
Angeles County Sanitation District (LACSD) is in charge
of the county's sanitation system. Among the many indus-
tries that used the sewer system was the Montrose Chemi-
cal Corp., the nation's largest manufacturer of DDT. From
the 1950s to 1971 tons ofDDT and associated manufactur-
ing waste entered the sewer system to be discharged ulti-
mately from the outfalls at White Point. In 1971, the last
year Montrose used the county sewers, an estimated 50,500
lbs. ofDDT were discharged from the outfalls. PCBs, an-
other persistent hazardous substance, also formed part of
the industrial waste stream that was discharged to the
sewer system until their ban in 1976. After these persistent
pollutants ceased to dominate the waste steam, LACSD
continued discharging treated waste onto Palos Verdes
Shelf. This created a layer of cleaner sediment on top of
the DDT- and PCB-contaminated sediment.
On the Palos Verdes Shelf, an estimated 5.7 million tons of
sediment have been affected by the effluent discharged
from the White Point outfalls. Mxed within these effluent-
affected (EA) sediments are an estimated 110 tons ofDDT
and 11 tons of PCBs. The EA sediment forms an identifi-
able deposit over a mile offshore at a depth of 150 feet to
the shelf break. The deposit ranges in thickness from 2
inches to over 2 feet, with the area of greatest accumula-
tion at 200 feet. It is thickest and has the highest concentra-
tions of DDTs and PCBs in the vicinity of the outfalls, then
fans out to the northwest. See Figures 3 and 4 .
Fate and Transport of the EA
Sediments
As stated earlier, discharge ofDDT and PCBs onto Palos
Verdes Shelf stopped in the 1970s and discharge of total
suspended solids had been reduced 97 percent by 2003.
Concentrations and quantities ofDDT and PCBs in the EA
sediment appear to be less today than in 1992. The EA de-
posit is buried under cleaner sediment; one of the questions
that will determine how best to deal with the remaining con-
tamination is will the deposit stay buried? The RI Report
examines the various processes that affect the EA sedi-
ments, discusses how they interact, and attempts to quantify
Institutional Controls Program
The Institutional Controls (ICs) program was put
in place to address the human health risks as-
sociated with consumption of certain fish, such
as white croaker, caught off the Palos Verdes
Peninsula that typically contain high concentra-
tions of DDTs and PCBs. The ICs program has
three components: public outreach and educa-
tion, fish monitoring, and enforcement. The pro-
gram relies on partnerships with other federal,
state and local agencies and community-based
organizations to enforce the commercial catch
ban and bag limit on white croaker and to edu-
cate the public on fishing practices and fish
preparation methods that minimize exposure to
contaminants. Information about the ICs program
can be found online atwww.pvsfish.org.
HVH
their importance for different parts of the shelf. Below are
brief discussions of the biological, chemical, and physical
processes that control the fate and transport of the EA sedi-
ment.
Biological
The roughly 1 foot of cleaner surface sediment covering the
more contaminated layer still contains measurable concen-
trations ofDDT and PCBs. How are the buried contami-
nants reaching the surface? One explanation is biological.
The shelf floor is home to worms, sea cucumbers, shrimp,
crabs and other invertebrates. Many of these pollutant-tol-
erant creatures turn the sediment just as earthworms work
topsoil. Although most of the mixing occurs in the top 6
inches, some larger species, such as ghost shrimp, can bring
up buried sediment from several feet below the surface.
This vertical mixing adds DDT and PCBs to the surface
sediments. The mixing also loosens the material, making it
more susceptible to resuspension. However, the inverte-
brates also consolidate sediment as they eat its organic mat-
Page 4
Palos Verdes Shelf Superfund Site

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ter and produce fecal pellets. A1992 study found as much
as 50 percent of the silt and clay fractions of the EA sedi-
ment had been pelletized.
Chemical
Most of the DDT on Palos Verdes Shelf converted quickly
to DDE or DDD, two DDT-related compounds. Recent
analysis indicates that, at least in some areas, the chemical
breakdown process is continuing. EPAhas limited but com-
pelling data on the occurrence of this process, called reduc-
tive dechlorination. Sediment cores collected inl992 off
Long Pt. at the 200 ft. depth were compared to cores col-
lected from the same location in 2005. Analysis of the
cores shows DDE is transforming into another a simpler,
related chemical called DDMU. Other breakdown prod-
ucts have been identified in these cores, as well. However,
very little is known about the toxicity of these breakdown
products. Reductive dechlorination would explain the reduc-
tion in DDE concentrations that are seen at depth in the de-
posit. However, chemical analyses of sediment cores
across the shelf would be required to determine if and to
what degree this transformation is occurring. There is no
evidence that PCBs, originally deposited on the shelf as in-
dustrial chemicals called "Aroclors," are undergoing reduc-
tive dechlorination. The observed loss of PCBs can be
attributed to dispersion.
Physical
Waves and currents suspend, deposit, and transport sedi-
ment along and away from the shelf. When the finer and
more organic particles that make up
the EA sediment are suspended, the
contaminants they contain are trans-
ported along with them. If more sedi-
ment is transported into an area than
is transported out, sediment will accu-
mulate. This tends to bury the existing
EA sediment, which appears to have
happened north of the outfalls. The
opposite occurs if sediment transport
out of an area is higher than the rate
of transport in; in which case the con-
taminated sediment is eroded. The
area southeast of the outfalls appears
to be erosive. Material resuspended
from the EA deposit, especially slowly
settling particles, can travel off the
Palos Verdes Shelf before settling
back to the bottom. Individual par-
ticles may undergo the process of
resuspension, transport, and deposition
many times and will gradually disperse
from the shelf, typically ending up in
on the slope or in the deeper basins
where they are resuspended less fre-
quently. The top layer of sediment is
most affected by these processes.
Over time, the fine sediment is win-
nowed out, leaving coarser, heavier
sediment, less susceptible to
resuspension by waves and currents.
Santa Monica
Bay
LOS ANGELES
COUNTY
Palos Verdes Peninsula
Palos Verdes
Point
Portuguese Bend
Ft. Vicente
Los Angeles
Harbor
White Point
Pt. Fermin
^ - EPA Sampling Location
a - LACSD Fish Sampling Zone
/12\ - MSRP Fish Sampling Segment
Figure 5: Palos Verdes Shelf fish sampling locations
Page 6
Palos Verdes Shelf Superfund Site

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Human Health and
Environmental Risks
Reassessed
EPA prepared a Human Health Risk Evaluation in 1999
using fish data from multiple sources and years. For the RI
Report, EPA used more recent data from the 2002 EPA-
Montrose Settlement Restoration Program Joint Ocean Fish
Survey and from LACSD's 2002 fish sampling (see
Figure 5) to reassess the human health risk. The harm
posed by the site is in the transfer of contaminants from the
sediment into the food chain. Fish accumulate DDTs and
PCBs when they eat worms, crabs and other creatures
living in the sediment. The reassessment analyzed DDT and
PCB tissue concentrations found in six species of fish
collected from the Palos Verdes Shelf Study Area: kelp
bass, white croaker, barred sandbass, rockfish, surfperches,
and California scorpionfish.
Both PCBs and DDT are known to have deleterious health
effects and are probable human carcinogens. EPA uses a
Hazard Index developed from a daily exposure or reference
dose to quantify potential noncancer health effects. A
hazard quotient of 1.0 is considered the threshold to indicate
an exceedance of the reference dose. EPA assumes there
is no safe exposure threshold for carcinogens; therefore,
EPA calculates risk from probable carcinogens as potential
increased cancer risk over a lifetime.
In reassessing human health risk for the RI Report, EPA
used two consumption scenarios: a reasonable maximum
exposure (RME) (i.e., consumption) of 107.1 grams of fish
a day and for high end consumers, 115.7 g/day (about a
quarter pound of fish a day). The other scenario, called a
central tendency exposure (CTE), represents a more varied
diet, where fish consumption would equal 21.4 g/day (one
5-ounce serving a week). Table 1 shows potential health
risks under these scenarios for each of the six fish. It is
worth noting that these health risks used DDT and PCB
concentrations found in fish tissue only. Both DDT and
PCBs are lipophilic, i.e., they accumulate in fat. Therefore,
whole fish concentrations are typically 8 to 10 times higher
than tissue concentrations. As a result, these risk values
underestimate exposure for people who consume whole
fish, such as in stews and other dishes.

Reasonable Maximum Exposure
Central Tendency Exposure
Fish Species
Cancer Risk
Noncancer HQ
(>1 exceeds reference dose)
Cancer Risk
Noncancer HQ
(>1 exceeds reference dose)
White Croaker
6 x 10"3
183
6 x 10"4
37
Kelp Bass
1 x 10"4
5
1 x 10"5
0.9
Rockfish
1 x 10"4
5
1 x 10"5
0.9
Surfperch
7 x 10"5
2
6 x 10"6
0.5
CA Scorpionfish
3 x 10"4
8
3 x 10"5
2
Barred Sandbass
3 x 10"4
10
3 x 10"5
2
Table 1: Cancer and noncancer health risks based on the 95 percent UCL (upper confidence limit) of the
mean concentration of contaminants found in these six species of fish caught from the Palos Verdes Shelf
Study Area. The Reasonable Maximum Exposure assumes a consumption rate of about a meal a day. The
Central Tendency Exposure assumes a consumption rate of about a meal a week.
February 2008
Page 7

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Palos Verdes Shelf Superfund
Site Update
Site Contacts:
Carmen White, SFD-7-1
Remedial Project Manager (Remedial
Investigation and Cleanup)
(415) 972-3010
white.carmen@epa.gov
Sharon Lin, SFD-7-1
Remedial Project Manager (Public Outreach and
Education, Monitoring
and Enforcement)
(415) 972-3446
lin.sharon@epa.aov
Jackie Lane,SFD-3
Community Involvement Coordinator
(415) 972-3236
lane.iackie@epa.gov
U.S. EPA Region 9
75 Hawthorne Street
San Francisco, CA 94105
Toll Free Hotline:
(800) 231-3075
For a copy of this fact sheet, visit www.pvflsh.org or call Toll Free 1-800-231-3075.
Para obtener una copia en espanol de esta hoja informativa, visite la pagina Web al:
www.pvsfish.org o llame a la linea gratuita al 1 800 231-3075.
, n&Vi www.pvsfish.org,	1 soo 231-3075.
Quy vi co the xem ban Tieng Viet cua cua ban du: kien nay tai trang web www.pvsfish.org hoac
yeu cSu qua s6 difn thoai Miln Phi 1 800 231-3075.

For more site information, visit the Region 9 Superfund Site overview page at
http://www.epa.gov/region09/waste/sfund/pvshelf.
For Site Repository locations, check the Site overview web page above.
United States Environmental Protection Agency
Region 9
75 Hawthorne Street (SFD-3)
San Francisco, CA 94105
Attn: Jackie Lane (PVS 12/07)
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