NPL­
U34­
2­
10­
R9
HRS
DOCUMENTATION
RECORD
­
REVIEW
COVER
SHEET
Name
DEL
AM0
Contact
(415)
744­
2343
Site
Investigation:
'
(415)
744­
2399
DocumentationRecord:
KateDragolovich,
Ecology
and
Environment,
Inc.
(
415)
981­
2811
Pathways,
Components,
or
Threats
Not
Scored:

The
surface
water
pathway
was
evaluated,
but
not
scored,
because
there
are
a
limited
number
of
targets
associated
with
the
first
7.5
iniles
of
the
15­
mile
in­
water
segment.
Runoff
from
the
Del
Am0
site
enters
a
storm
drain
inlet
located
at
the
intersection
of
Vermont
Avenue
and
Del
Am0
Boulevard,
approximately
600
feet
southeast
of
Sources
1
and
2.
The
storm
drain
system
discharges
into
the
Torrance
Lateral,
which
is
an
open
channel,
approximately
1,600
feet
south
of
the
storm
drain
inlet.
The
Torrance
Lateral
discharges
into
the
Dominguez
Channel,
which
is
a
concrete­
lined
drainage
and
flood
control
channel,
approximately
1.5
miles
downstream
of
the
storm
drain
system
discharge
point.
The
Dominguez
Channel
discharges
into
the
Los
Angeles
Harbor
approximately
6
miles
farther
downstream.
The
Los
Angeles
Harbor
empties
into
San
Pedro
Bay,
and
San
Pedro
Bay
opens
onto
the
Pacific
Ocean.
The
last
portion
of
the
15­
mile
in­
water
segment
consists
of
an
arc
with
a
7.5­
mile
radius
that
extends
from
the
confluence
of
the
Dominguez
Channel
and
the
Los
Angeles
Harbor
into
San
Pedro
Bay
and
the
Pacific
Ocean.
Although
there
are
fisheries
and
sensitive
environments
associated
with
the
Los
Angeles
Harbor,
San
Pedro
Bay,
and
the
Pacific
Ocean,
there
do
not
appear
to
be
any
&inking
water
intakes
or
sensitive
environments
associated
with
the
first
7.5
miles
of
the
15­
mile
in­
water
segment
(i.
e.,
the
Torrance
Lateral
and
concrete­
lined
Dominguez
Channel).
In
addition,
there
are
a
limited
number
of
fish
in
the
Dominguez
Channel.

The
soil
exposure
pathway
was
evaluated,
but
not
scored,
because
the
area
of
the
Del
Am0
site
that
is
occupied
by
Sources
1
and
2
is
currently
vacant
and
covered
with
fill
material
and
vegetation.
In
addition,
Soyrces
1
and
2
are
separated
from
Del
Am0
Boulevard
and
a
residential
area
to
the
south
by
a
doubIe,
rod'of
fences.
Source
3
is
currently
present
as
an
area
of
non­
aqueous
phase
liquid
(NAPL)
located
60
feet
below
ground
surface.

The
air
pathway
was
evaluated,
but
not
scored,
because
no
known
ambient
air
sampling
and
meteorological
monitoring
have
been
conducted
on
or
in
the
vicinity
of
the
Del
Am0
site.
HRS
DOCUMENTATION
RECORD
Name
of
Site:
DEL
AM0
EPA
ID#:
CAD02954473
1
EPA
9
I
Date
Prepared:
August
15,2000
StreetAddress
of
Site:
Del
Am0
BoulevardandVermontAvenue,
LosAngeles
CountyandState:
Los
AngelesCounty,
California
TopographicMap:
Torrance
Latitude:
33"
50'
47.9"
N.
Longitude:
118"
17'
22.1"
W.
Reference
Point:
Intersection
of
Del
Am0
Boulevard
and
Vermont
Avenue
(ref.
4)

.
Scores
Ground
Water
Pathway
94.23
Surface
Water
Pathway
Not
scored
Soil
Exposure
Pathway
Not
scored
Air
Pathway
Not
scored
HRS
SITE
SCORE
47.12
1
HAZARD
RANKING
SYSTEM
SUMMARY
SCORESHEETS
SITE
NAME:
DelAm0
CITY/
COUNTY/
STATE:
Los
Angeles.
Los
Angeles
Countv,
California
EPA
ID
#:
CAD02954473
1
EVALUATOR
KateDragolovich
DATE:
Aumst
15,2000
LATITUDE:
33"
50'
47.9"
N.
LONGITUDE:
118"
17'22.1"
W.

sw
s
a
2
GROUND
WATER
MIGRATION
PATHWAY
SCORESHEET
Factor
Categories
and
Factors
1.
2.

3.

4.
5.
6.

7.
8.

9.
10.
11.

12.
Likelihood
of
Release
Observed
Release
Potential
to
Release
2a.
Containment
2b.
Net
Precipitation
2c.
Depth
to
Aquifer
2d.
Travel
Time
2e.
Potential
to
Release
[Lines
2a(
2b+
2c+
2d)}
Likelihood
of
Release
(Higher
of
lines
1
and
2e)

Waste
Characteristics
ToxicityMobility
Hazardous
Waste
Quantity
Waste
Characteristics
Targets
Nearest
Well
Population
8a.
Level
I
Concentrations
8b.
Level
11
Concentrations
8c.
Potential
Contamination
8d.
Population
(lines
8a+
8b+
8c)
Resources
Wellhead
Protection
Area
Targets
(lines
7+
8d+
9+
10)

Aquifer
Score
[(
lines
3
x
6
x
11)/
82,500]

Ground
Water
Migration
Pathway
Score
13.
'
PathwayScore
(S,),
highestvaluefrom
line
12
for
all
aquifers
eva1uated)
c
Maximum
Value
550
10
10
5
35
500
550
a
a
100
50
aMaximumvalueappliestowastecharacteristicscategory.
bMaximumvalue
not
applicable.

C
Do
notroundtonearestinteger.
b
b
b
b
5
20
b
100
100
Value
Assigned
­
550
­
550
­
100
10,000
­
32
­
5
­
0
­
0
436.7
436.7
­
0
­
0
441.7
94.23
94.23
REFERENCES
Reference
NumberDescriptionoftheReference
1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.
U.
S.
Environmental
Protection
Agency,
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Ranking
System
(40
CFR
Part
300,
Appendix
A),
Final
Rule,
55
FR
51532,
December
14,1990,
134
pages.

U.
S.
Environmental
Protection
Agency,
Superfund
Chemical
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Matrix
(SCDM),
June
19964
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Map
Showing
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Location
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Del
Amo
Site
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the
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S.
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1964,
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198
1.

Dames
&
Moore,
Phase
I
Remedial
Investigation
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Del
Am0
Study
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Los
Angeles,
California,
for
Shell
Oil
Company
and
The
Dow
Chemical
Company,
October
29,
1993,229
pages.

Map
Showing
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of
Sources
1,2,
and
3
at
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Amo
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Dames
&
Moore,
Feasibility
Study
Report,
Del
Amo
Site,
May
1991,48
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T.
R.,
Shell
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Company,
letter
to
Thomas
E.
Bailey
(with
attachments),
California
Department
of
Health
Services,
November
30,
1983,7
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Page,
Bruce
W.,
Levine­
Fricke,
Del
Amo
Site
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May
21,1993,23
pages.

Rubber
Producing
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Disposal
Commission,
Government­
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Synthetic
Rubber
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Plancor
929,
Los
Angeles,
California,
November
1953,7
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Dames
&
Moore,
Radian
Corporation,
Interim
Summary
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Findings,
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Am0
Site
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California,
for
Ire11
&
Manella,
June
1984,45
1
pages.

Dames
&
Moore,
Draft
Waste
Excavation
Feasibility
Study
Report,
Del
Am0
Pit
Site,
for
Shell
Oil
Company
and
The
Dow
Chemical
Company,
November
20,1992,345
pages.

Bolton,
R.
L.
and
L.
Klein,
SewaEe
Treatment
­
Basic
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and
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Ann
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Science
Publishers,
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Michigan,
1971,
8
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Manahan,
Stanley
E.,
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Lewis
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199
1,7
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4
15.

16.

17.

18.

19.

20.

21.

22.

23.

24.

25.

26.

27.

28.

29.
State
of
California
Department
of
Water
Resources,
Bulletin
104,
Planned
Utilization
of
the
Ground
Water
Basins
of
the
Coastal
Plain
of
Los
Angeles
County,
Appendix
A
Ground
Water
Geology,
June
1961,30
pages.

Hargis
+
Associates,
Inc.,
Final
Draft
Remedial
Investigation,
Montrose
Site,
Torrance,
California,
prepared
for
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Chemical
Corporation,
October
29,
1992,237
pages.

Ross,
J.
E.,
California
Regional
Water
Quality
Control
Board,
Los
Angeles
Region,
memorandum
to
Haissan
Salloum,
California
Environmental
Protection
Agency,
Department
of
Toxic
Substances
Control,
Long
Beach,
supplement
to
General
ARARs
memo
of
October
19,
1993,3
pages.

California
Regional
Water
Quality
Control
Board,
Los
Angeles
Region,
Interim
Guidance
for
Remediation
of
Petroleum
Impacted
Site
­
Soil
Screening
Levels,
November
1994,2
pages.

Hargis
+
Associates,
Inc.,
Results
of
Aquifer
Testing,
Montrose
Site,
Torrance,
California,
prepared
for
Montrose
Chemical
Corporation
of
California,
October
3
1,
1990,20
pages.

Witthoft,
Terry
H.,
Dominguez
Water
Corporation,
letter
to
Kate
Dragolovich
(with
attachments),
Bechtel
Environmental,
Inc.,
November
22,
1993,5
pages.

Dames
&
Moore,
Phase
I
Treatability
Study
Evaluation
Report,
Del
Am0
Pit
Site,
LOS
h
g
e
k
California,
April
5,
1993,30
pages.

Dames
&
Moore,
Quarterly
Report,
Groundwater
Monitoring
Program,
First
Quarterly
Sampling
Event,
1994,
Del
Amo
Study
Area,
for
Shell
Oil
Company
and
The
Dow
Chemical
Company,
July
22,
1994,
12
pages.

Johnson,
Thomas
M.,
Levine­
Fricke,
Del
Am0
Site,
May
21,
1993,26
pages.

Hargis
+
Associates,
Inc.,
Raw
Analytical
Data
Submittal
Part
2,
Remedial
Investigative
Work,
Phase
2B,
Montrose
Site,
Torrance,
California,
April
1990
Groundwater
Sampling,
June
20,
1990,78
pages.

Hargis
+
Associates,
Inc.,
Raw
Analytical
Data
Submittal,
Montrose
Site,
Torrance,
California,
August
1990
Quarterly
Groundwater
Sampling,
September
18,
1990,40
pages.

Hargis
+
Associates,
Inc.,
Field
and
Raw
Analytical
Data
Submittal,
Semiannual
Groundwater
Sampling,
November­
December
1990,
Montrose
Site,
Torrance,
California,
January
30,
1991,
121
pages.

Hargis
+
Associates,
Inc.,
Field
and
Raw
Analytical
Data
Submittal,
Semiannual
Groundwater
Sampling,
April
1991,
Montrose
site,
Torrance,
California,
June
7,
1991,46
pages.

Hargis
+
Associates,
Inc.,
Field
and
Raw
Analytical
Data
Submittal,
Semiannual
Groundwater
Sampling,
July
1992,
Montrose
Site,
Torrance,
California,
September
3,
1992,46
pages.

Hargis
+
Associates,
Inc.,
Field
and
Raw
Analytical
Data
Submittal,
Semiannual
Groundwater
Sampling,
January
1993,
Montrose
Site,
Torrance,
California,
March
11,
1993,46
pages.
.
x­

5
30.
Hargis
­t
Associates,
Inc.,
Field
and
Raw
Analytical
Data
Submittal,
Additional
Groundwater
Assessment
Monitor
Well
Installation,
Groundwater
and
Soil
Sampling,
May
through
November
1991,
Montrose
Site,
Torrance,
California,
December
19,
1991,41
pages.

3
1.
Woodward­
Clyde
Consultants,
Task
2
Final
Report,
Additional
Data
Acquisition,
Del
Amo
Hazardous
Waste
Site,
Los
Angeles,
CA,
prepared
for
the
California
Department
of
Health
Services,
October
2,
1987,329
pages.

32.
Map
Showing
Locations
of
Drinking
Water
Wells
Within
4
Miles
of
Sources
1,2,
and
3
at
the
Del
Am0
Site.

33.
Goclowski;
Clara
Patricia,
Southern
California
Water
Company,
letter
to
Kate
Dragolovich
(with
attachments),
Bechtel,
December
3,
1993,
lO
pages.

34.
Schaich,
Chuck,
City
of
Torrance
Water
Company,
Telephone
conversation
recorded
on
Contact
Report
by
Jordie
Bornstein,
Bechtel
Environmental,
Inc.,
March
30,
1995,
1
page.

35.
Witthoft,
Terry,
Dominguez
Water
Company,
Telephone
conversation
recorded
on
Contact
Report
by
I
Jordie
Bornstein,
Bechtel
Environmental,
Inc.,
March
30,
1995,
1
page.

36.
Polarico,
Anna,
Southern
California
Water
Company,
Telephone
conversation
recorded
on
Contact
Report
by
Jordie
Bornstein,
Bechtel
Environmental,
Inc.,
March
29,
1995,
1
page.

37.
Census
of
Population
and
Housing,
1990:
Summary
Tape
File
3
on
CD­
ROM
(machine­
readable
data
files),
prepared
by
the
Bureau
of
the
Census,
1992.
Available:
http://
govinfo.
library.
orst.
edu/
stateis.
html
[viewed
February
29,
2000],
5
pages.

38.
Witthoft,
Terry,
Dominguez
Water
Company,
Telephone
conversation
recorded
on
Contact
Report
by
Kate
Dragolovich,
Ecology
and
Environment,
Inc.,
February
17,2000,2
pages.

39.
Schaich,
Chuck,
City
of
Torrance
Water
Company,
Telephone
conversation
recorded
on
Contact
Report
by
Kate
Dragolovicli,
Ecology
and
Environment,
Inc.,
February
24,2000,
1
page.

40.
Hartsock,
Mike,
SouthernCaliforniaWaterCompany,
TelephoneconversationrecordedonContact
Report
by
Kate
Dragolovich,
Ecology
and
Environment,
Inc.,
February
11,2000,2
pages
41.
California
Department
of
Fish
and
Game,
Natural
Diversity
Data
Base
(NDDB)
Printout
(Torrance,
Long
Beach,
and
San
Pedro
quadrangles)
and
instructions
for
reading
the
NDDB
Printout,
Expires
March
8,
1995,22
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42.
Smith,
Tim,
Los
Angeles
County
Department
of
Public
Works,
Telephone
conversation
recorded
on
Contact
Report
by
Jordie
Bornstein,
Bechtel
Environmental,
Inc.,
April
19,
1995,
1
page.

6
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44.

45
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49.

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52.

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55.

56.

57.
Dames
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Moore,
Remedial
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Report,
Del
Am0
Site,
April
4,
1990,
11
pages.

Map
Showing
Surface
Water
Migration
Pathway,
Del
Am0
Site.

Hargis
&
Associates,
Inc.,
Regional
Hydrogeologic
Assessment
Report,
Task
15,
May
29,
1990,2
pages.

Dhont,
Jeff,
U.
S.
Environmental
Protection
Agency,
Region
9,
Memorandum
to
Murray
Newton
(OSWER­
R1­
9ARC),
Alan
Youkeles,
and
Karen
Bankert,
U.
S.
Environmental
Protection
Agency,
June
6,
1996,2
pp.

Dames
&
Moore,
Groundwater
Monitoring
Report,
Third
Sampling
Period
1995,
Del
Am0
Study
Area,
for
Shell
Oil
Company
and
The
Dow
Chemical
Company,
February
23,
1996,590
pages.

Schaich,
Chuck,
City
of
Torrance
Water
Company,
Telephone
conversation
recorded
on
Contact
Report
by
Kate
Dragolovich,
Ecology
and
Environment,
Inc.,
March
10,2000,
1
page.

Dames
&
Moore,
Final
Groundwater
Remedial
Investigation
Report,
Del
Am0
Study
Area,
May
15,
1998,602
pages.

Dames
&
Moore,
Focused
Investigation,
Nature
and
Extent
of
Non­
Aqueous
Phase
Liquid
(NAPL),
Monitoring
Well
MW­
20,
Del
Amo
Study
Area,
March
5,
1993,
36
pages.

U.
S.
Environmental
Protection
Agency,
Record
of
Decision
for
dual
Site
Groundwater
Operable
Unit,
Montrose
Chemical
Company
and
Del
Am0
Superfund
Sites,
March
1999,
18
pp.

Figure
showing
Lateral
Extent
of
Non­
Aqueous
Phase
Liquid
(NAPL)
and
Area
Used
to
Determine
Volume
for
Tier
A
Waste
Quantity
Calculations.

Dames
&
Moore,
Draft
Interim
Data
Submittal
and
Proposed
Laboratory
Testing
Program,
MW­
20
Pilot
Program,
Del
Amo
Study
Area,
September
24,
1994,22
pages.

Dames
&
Moore,
MW­
20
Pilot
Program,
Core
Photography
and
Record
of
In­
Laboratory
Testing
and
Sample
Aliquot
Locations,
SBL0085
and
SBL0086,
Del
Am0
Study
Area,
September
16,
1994,14
pages.

Dames
&
Moore,
MW­
20
Pilot
Program,
Core
Photography
and
Record
of
In­
Laboratory
Testing
and
Sample
Aliquot
Locations,
SBL0087
and
SBL0088,
Del
Am0
Study
Area,
September
16,1994,20
pages.

Dames
&
Moore,
MW­
20
Pilot
Program,
Core
Photography
and
Record
of
In­
Laboratory
Testing
and
Sample
Aliquot
Locations,
SBL0089
and
SBL0090,
Del
Am0
Study
Area,
September
16,1994,29
pages.
_"

7
58.
Dames
&
Moore,
MW­
20
Pilot
Program,
Core
Photography
and
Record
of
In­
Laboratory
Testing
and
Sample
Aliquot
Locations,
SBL0091
and
SBL0092,
Del
Am0
Study
Area,
September
16,1994,22
pages.

59.
Dames
&
Moore,
MW­
20
Pilot
Program,
Core
Photography
and
Record
of
In­
Laboratory
Testing
and
Sample
Aliquot
Locations,
SBL0093
and
SBL0094,
Del
Am0
Study
Area,
September
16,1994,14
pages.

60.
Dames
&
Moore,
Draft
Report
and
Work
Plan,
Laboratory
Data
and
Analysis
and
Hydraulic
..

Extraction
Work
Plan,
MW­
20
Pilot
Program,
Del
Am0
Study
Area,
September
29,
1995,41
pages.

61.
ChemFinder.
Com.
SearchResultPage,
Benzene.
Available:
http://
chemfinder.
camsoft.
com/
result.
asp
[viewed
March
13,20001,
1
page.

62.
Figure
Showing
Depth
of
Soil
Contamination
Beneath
Source
1
in
1987
and
Rising
Water
Table
Elevations
in
1987,1993,1994,
and
1995.

8
SD­
Characterization
and
Containment
Source
1
SOURCE
DESCRIPTION
2.2
Source
Characterization
Source
Description:
Source
1
­
Pits
2A,
2B,
2C,
2D,
2E,
and
2F
Source
1
consists
of
six
disposal
pits
(Pits
2A,
2B,
2C,
2D,
2E,
and
2F)
that
are
adjacent
to
one
another
and
arranged
in
a
linear
east­
west
alignment
(ref.
5,
Plate
3­
3;
ref.
6).

Aerial
photographs
indicate
that
the
pits
were
first
present
sometime
after
1941
and
before
1947
(ref.
5,
p.
3­
6).
They
are
man­
made
excavations
formed
from
earthen
materials
that
were
designed
to
hold
semi­
'

viscous
and
viscous
sludges
(i.
e.
process
wastes
that
originated
from
the
styrene
manufacturing
plant
that
was
historically
on
site)
(ref.
5,
p.
3­
6;
ref.
8,
pp.
6
and
7;
ref.
9,
p.
15).
Each
pit
has
a
small
protrusion
at
its
northern
end
(ref.
5,
Plate
3­
3).
The
function
or
significance
of
the
protrusions
is
not
known;
however,
it
may
relate
to
or
reflect
the
method(
s)
used
to
excavate
the
pits,
or
to
transport
and
discharge
waste
materials
to
the
pits
(ref.
7,
p.
2­
2).
Once
in
the
pits,
the
waste
sludges
were
left
open
to
the
air,
allowed
to
drain
and
dry,
and
then
hauled
away
by
truck
(ref.
10,
p.
6).

Aerial
photographs
indicate
that,
by
December
1951,
the
pits
were
covered
with
fill
material
(ref.
5,
p.
3­
6).
The
source
of
the
fill
material
is
not
known;
however,
it
is
probably
natural
local
soil
(ref.
8,
p.
7).
Field
data
and
visual
observations
of
core
samples
collected
from
the
pits
in
1984
indicate
that
the
fill
material
covering
the
remaining
waste
ranges
in
thickness
from
approximately
1
foot
overlying
Pit
2A
to
8
feet
overlying
Pit
2F
(ref.
11,
p.
4­
30,
Table
4.3­
4).
The
fill
material
is
covered
with
weeds
and
miscellaneous
debris
(e.
g.,
old
tires
and
broken
glass)
(ref.
5,
p.
5­
23).

The
six
pits
are
separated
from
Del
Am0
Boulevard
and
a
residential
area
to
the
south
by
a,
double
row
of
fences
(ref.
5,
p.
5­
23).

Three
wastes
from
the
former
styrene
manufacturing
plant
(i.
e.,
acid
sludge,
clay­
like
sludge,
and
sulfur
tar
oil)
are
known
to
have
been
disposed
of
in
Source
1
(ref.
9,
pp.
12,13).
The
acid
sludge
resulted
from
the
purification
of
crude
benzene
using
sulfuric
acid
to
remove
the
sulfur­
containing
compounds
and
unsaturated
components
(ref.
9,
pp.
3,4;
ref.
10,
p.
4).
The
clay­
like
sludge
resulted
from
the
conversion
of
ethanol
to
ethylene
using
kaolin
clay
as
a
catalyst
under
thermal
conditions
(ref.
9,
pp.
12,
13).
The
purified
benzene
and
ethylene
that
were
generated
by
these
two
processes
were
then
combined
to
form
ethylbenzene.
The
ethylbenzene
was
neutralized
and
purified
before
being
fed
into
dehydrogenation
units
where
it
was
partially
converted
to
styrene.
The
crude
styrene
contained
35
to
40
percent
styrene,
ethylbenzene,
and
small
amounts
of
benzene
and
toluene.
It
was
fed
into
styrene
purification
units
where
a
distillation
tower
was
used
to
remove
the
benzene
and
toluene,
and
primary
and
secondary
stills
were
used
to
remove
the
ethylbenzene.
Sulfur
was
introduced
at
various
steps
in
the
purification
process
to
inhibit
thermal
polymerization
of
the
styrene.
The
final
step
in
the
purification
process
was
to
feed
the
bottoms
from
the
ethylbenzene
stills
into
a
short
packed
tower
where
tar
and
sulfur
were
removed
&d
99+
percent
styrene
was
produced.
Sulfur
tar
oil
waste
was
generated
during
this
final
step
(ref.
9,
pp.
5
through
7;
ref.
10,
p.
4).

9
SD­
Characterization
and
Containment
Source
1
Observations
made
during
boring
and
sampling
activities
indicate
that
the
waste
remaining
in
the
pits
consists
of
black
to
gray­
black
tars
to
day­
like
sludges
(ref.
12,
p.
11).
This
waste
contains
hydrocarbons
with
high
polynuclear
aromatic
and
volatile
aromatic
content,
which
correlates
with
the
chemistry
of
the
styrene
manufacturing
process
wastes
described
above.
Naphthalene
is
the
dominant
polynuclear
aromatic
compound
in
the
waste,
while
benzene
and
ethylbenzene
are
the
dominant
volatile
aromatic
compounds
(ref.
5,
p.
5­
25;
ref.
7,
p.
iii;
ref.
9,
pp.
12,
13).
In
addition,
significant
downhole
emissions
of
hydrogen
sulfide
(H2S)
occur
in
the
pits
(ref.
5,
p.
5­
24).
This
correlates
with
conditions
in
the
pits
that
are
conducive
to
the
formation
of
H,
S
(e.
g.,
the
presence
of
sulfur
in
the
waste
and
a
pH
in
the
acidic
range)
(ref.
5,
p.
5­
25;
ref.
7,
Table
2­
9;
ref.
13,
pp.
11
through
18;
ref.
14,
pp.
156,289,290,
and
508).

Source
Tvpe
The
source
type
for
Source
1
is
"buried
surface
impoundment"
(ref.
1,
Table
2­
5).

Source
Location
Source
1
is
located
in
the
portion
of
the
Del
Amo
site
that
was
formerly
occupied
by
the
styrene
manufacturing
plant.
Pits
2A,
2B,
2C,
2D,
2E,
and.
2F
are
approximately
150
feet
north
of
De)
Am0
Boulevard
(ref.
5,
Plate
3.3;
ref.
6).

Source
Containment
Release
to
Ground
Water
Source
1
has
no
liner
(ref.
5,
p.
3­
6).
Analytical
results
provide
evidence
of
vertical
hazardous
substance
migration
from
the
waste
in
Source
1
to
the
soil
immediately
beneath
the
pits
(ref.
5,
pp.
5­
26,
5­
29,
5­
30,
5­
31,
Tables
5.5­
3
through
5.5­
16,
Figures
5.5­
1,5.5­
10).
See
Section
3.1.1
(Observer
Release
­
Direct
Observation)
for
a
more
detailed
discussion
of
the
analytical
results.
A
ground
water
containment
factor
value
of
10
is
assigned
for
"evidence
of
hazardous
substance
migration
from
source
area"
(ref.
1,
Table
3­
2).

10
SD
­
Hazardous
Substances
Source
1
2.4.1
Hazardous
Substances
Hazardous
Substance
Evidence
'
Reference
benzene
waste
sample
nos.*
11,
Table
5.2­
1,

SO
14
p.
B­
15
S044,
SO48
p.
B­
16
S068,
SO72
p.
B­
17
ethylbenzene
s2oo
S206
s220
waste
sample
nos.**

SSSOOOOl
thru
SSSOOOO4
sssooo11,
sss00012
sssooo21
wss00001
thru
wssoooo3
wssooo13,
wssooo14
wssooo15
WSSOOO16,

waste
sample
nos.*

SO14
S
O
U
,
SO48
S068,
SO72
s200
S206
s220
waste
sample
nos.%%

SSSOOOOl
thru
SSSOOOO4
p.
B­
18
p.
B­
19
p.
B­
20
12,

pp.
A3­
5,
A4­
5
pp.
A3­
7,
A4­
19
pp.
A3­
3,
A437
pp.
A3­
3,
A4­
37
pp.
A3­
6,
A4­
75
pp.
A3­
8,
A4­
75
pp.
A3­
4,
A4­
75
1
1,
Table
5.2­
1,

p.
B­
15
\

p.
B­
16
p.
B­
17
p.
B­
18
p.
B­
19
p.
B­
20
12,

pp.
A3­
5,
A4­
6
1
1
naphthalene
sssooo11,
sssooo12
sssooo21
wssoooo1,
wssoooo2
wssooo14
wssooo15
WSSOOO16
waste
sample
nos.

SO14
S044,
SO48
S068,
SO72
s200
S206
s220
waste
sample
nos.%%

SSSOOOOl
thru
SSSOOOO4
sss00011
sssooo21
wss00001
t
h
wssoooo3
wssooo13,
wssooo14
wssooo15
WSSOOO16
SD
­
Hazardous
Substances
Source
1
pp.
A3­
7,
A4­
20
pp.
A3­
3,
A4­
38
pp.
A3­
3,
A4­
38
pp.
A3­
6,
A4­
76
pp.
A3­
8,
A4­
76
pp.
A3­
4,
A4­
76
11,
Table
5.2­
1,

p.
B­
25
p.
B­
26
p.
B­
27
p.
B­
28
p.
B­
29
p.
B­
30
12,

pp.
A3­
5,
A4­
4
pp.
A3­
7,
A4­
17
pp.
A3­
3,
A4­
35
pp.
A3­
3,
A4­
35
pp.
A3­
6,
A4­
73
pp.
A3­
8,
A4­
73
pp.
A3­
4,
A4­
73
I
In
1984,
Dames
&
Moore,
under
contract
to
Ire11
&
Manella,
drilled
eight
soil
borings
in
Source
1
(i.
e.,
borings
2­
IV,
2­
IVa,
and
2­
IVb
in
Pit
2A;
boring
2­
111
in
Pit
2B;
boring
2­
11
in
Pit
2C;
boring
2­
V
in
Pit
2D;
boring
2­
1
in
Pit
2E;
and
boring
2­
W'in
Pit
2F)
to
characterize
the
fill
material
overlying
the
waste,
the
waste,
and
the
soil
beneath
the
waste
(ref.
11,
p.
4­
24,
Figure
4.3­
1).
Five
to
17
soil
and/
or
waste
samples
were
collected
from
each
boring
(67
total)
at
2.5­
foot
or
5­
foot
intervals
from
ground
surface
to
a
depth
of
51.5
feet
below
ground
surface
(bgs)
(ref.
11,
pp.
4­
26,4­
27,
Table
4.3­
2).
Of
the
67
samples,
the
following
eight
samples
consisting
entirely
of
waste
were
selected
for
chemical
analysis:
S200
from
boring
2­
IV
in
Pit
2A,
SO68
and
SO72
from
boring
2­
III
12
SD
­
Hazardous
Substances
Source
1
in
Pit
2B,
SO44
and
SO45
from
boring
2­
II
in
Pit
2C,
S206
from
boring
2­
V
in
Pit
2D,
SO14
from
boring
2­
1
in
Pit
2E,
and
S220
from
boring
2­
VI
in
Pit
2F
(ref.
11,
Tables
4.3­
2,5.2­
1,
Appendix
A,
pp.
A­
5
through
A­
10).
All
eight
samples
were
analyzed
for
purgable
aromatics
using
EPA
Method
602
and
extractable
hydrocarbons
using
EPA
Method
610.
Analytical
results
indicated
the
presence
of
benzene,
ethylbenzene,
and
naphthalene
at
concentrations
up
to
7,900
milligrams
per
kilogram
(mag),
1,840
m
a
g
,
and
126
m
a
g
,
respectively,
in
the
waste
in
Pit
2A;
23,000
m
a
g
,
9,300
mgkg,
and
300
m
a
g
,
respectively,
in
the
waste
in
Pit
2B;
7,100
m
a
g
,
3,800
mglkg,
and
150
_.

mgkg,
respectively,
in
the
waste
in
Pit
2C;
6,700
m
a
g
,
3,600
m
a
g
,
and
164
m
a
g
,
respectively,
in
the
waste
in
Pit
2D;
26,700
mglkg,
13,200
mglkg,
and
409
m
a
,
respectively,
in
the
waste
in
Pit
2E;
and'31,
OOO
mgkg,
11,600
m
a
g
,
and
304
m
a
g
,
respectively,
in
the
waste
in
Pit
2F
(ref.
11,
p.
5­
6,
Appendix
B,
pp.
B­
15
through
B­
20,
B­
25
through
B­
30).

%%
In
1992,
Dames
&
Moore,
under
contract
to
Shell
Oil
Company
and
Dow
Chemical
Company,
drilled
six
soil
borings
in
Source
1
(i.
e.,
borings
SBL0001,
SBL0006,
SBL0007,
and
SBL0008
in
Pit
2C;
boring
SBL0002
in
Pit
2D;
and
boring
SBL0003
in
Pit
2F)
as
part
of
a
waste
excavation
feasibility
study
(ref.
12,
p.
1,
Appendix
A,
Figure
A­
1).
Eight
waste
samples
(SSS00001
through
SSSOO004,
and
WSSOOO13
through
WSS00016)
collected
from
Pit
2C,
two
waste
samples
(SSSOOOll
and
SSSOOOl2)
collected
from
Pit
2D,
and
four
waste
samples
(SSSOOO21,
and
WSSOOOOl
through
WSSOOOO3)
collected
from
Pit
2F
were
analyzed
for
volatile
organic
compounds
using
EPA
Method
8240
and
for
polynuclear
aromatic
hydrocarbons
using
EPA
Method
8270
(ref.
12,
Appendix
A,
p.
A­
2,
Attachment
A3,
pp:
A3­
3
through
A3­
8,
Attachment
A4,
pp.
A4­
2
through
A4­
6,
A4­
15
through
A4­
20,
A4­
33
through
A4­
39,
A4­
71
through
A4­
77).
Analytical
results
indicated
the
presence
of
benzene,
ethylbenzene,
and
naphthalene
at
concentrations
up
to
21,000
mgkg,
8,500
mgkg,
and
68
mgkg,
respectively,
in
the
waste
in
Pit
2C;
29,000
mgkg,
8,300
mglkg,
and
120
mgkg,
respectively,
in
the
waste
in
Pit
2D;
and
52,000
mgkg,
8,600
mgkg,
and
240
mgkg,
respectively,
in
the
waste
in
Pit
2F
(ref.
12,
Appendix
A,
Attachment
A4,
pp.
A4­
17,
A4­
19,
A4­
20,
A4­
35,
A4­
37,
A4­
38,
A4073,
A4­
75,
A4­
76).

The
hazardous
substances
associated
with
Source
1
include:

benzene
ethylbenzene
*
naphthalene
Other
hazardous
substances
are
associated
with
Source
1
(e.
g.,
toluene,
styrene,
and
H,
S)
(ref.
5,
pp.
5­
24,
5­
25).
The
documentation
presented
above
is
limited
to
benzene,
ethylbenzene,
and
naphthalene
because
these
three
hazardous
substances
are
the
dominant
constituents
of
the
hydrocarbon
waste
remaining
in
Pits
2A
through
2F
(ref.
7,
p.
iii).

13
SD­
Hazardous
Waste
Quantity
Source
1
2.4.2
Hazardous
Waste
Quantity
*

Tier
A:
Hazardous
Constituent
Ouantitv
Documentation
is
not
sufficient
to
determine
hazardous
constituent
quantity.

14
Hazardous
Constituent
Quantity
Value:
0
SD­
Hazardous
Waste
Quantity
Source
1
Tier
B:
Hazardous
Wastestream
Ouantitv
Documentation
is
not
sufficient
to
determine
hazardous
wastestream
quantity.

Hazardous
Wastestream
Quantity
Value:
0
15
SD­
Hazardous
Waste
Quantity
Source
1
Tier
C:
Source
Volume
Documentation
is
not
sufficient
to
determine
the
volumes
of
Pits
2A
through
2F.

Volume
Assigned
Value:
0
J
16
SD­
Hazardous
Waste
Quantity
Source
1
Tier
D:
Source
Area
A
1947
aerial
photograph
shows
the
surface
areas
of
Pits
2A
through
2F
(ref.
11,
Figure
1.0­
1,
Table
4.3­
4).

Pit
2A
Pit
2B
Pit
2C
Pit
2D
Pit
2E
'Pit
2F
Total
Surface
Area
(not
including
protrusions)
(ft2,

1,650
1,625
1,625
1,9
14
1,625
9,464
Area
Value
(A):
9,464
ft2
Reference:
1
1,
Figure
1
.O­
1,
Table
4.3­
4
Area
Assigned
Value
(N13):
728
17
I
SD­
Hazardous
Waste
Quantity
Source
1
Source
Hazardous
Waste
Ouantitv
Based
on
Tier
D,
the
hazardous
waste
quantity
associated
with
this
source
is
728.

Source
Hazardous
Waste
Quantity:
728
18
SD­
Characterization
and
Containment
Source
2
SOURCE
DESCRIPTION
2.2
Source
Characterization
Source
Description:
Source
2
­
Ponds
1B
and
1C
Source
2
consists
of
two
rectangular
evaporation
ponds
(Ponds
1B
and
1C)
that
are
adjacent
to
one
another
and
arranged
in
a
linear
east­
west
alignment
(ref.
5,
Plate
3­
3;
ref.
6).

Aerial
photographs
indicate
that
Ponds
1B
and
1C
were
first
present
in
1946
(ref.
5,
p.
3­
6).
They
are
manmade
excavations
formed
from
earthen
materials
that
were
designed
to
hold
aqueous
wastes
(e.
g.,
propane
cracking
oils
generated
by
the
production
of
ethylene
from
propane
at
the
historic
styrene'
manufacturing
plant)
(ref.
8,
p.
7;
ref.
9,
p.
15).

Aerial
photographs
indicate
that,
by
1967,
both
ponds
had
been
covered
with
fill
material
(ref.
5,
p.
3­
6).
The
source
of
the
fill
material
is
not
known;
however,
it
is
probably
soil
that
was
originally
used
as.
diking
around
the
perimeter
of
the
ponds
(ref.
8,
p.
7).
Field
data
and
visual
observations
of
core
samples
collected
from
the
ponds
in
1984
indicate
that
the
fill
material
overlying
the
waste
in
Pond
1B
is
3.8
feet
thick.
The
fill
material
is
absent
from
some
areas
in
Pond
lC,
resulting
in
exposed
waste
at
ground
surface
(ref.
11,
p.
4­
30,
Table
4.3­
4).
The
fill
material
is
covered
with
weeds
and
miscellaneous
debris
(e.
g.,
old
tires
and
broken
glass)..(
ref.
5,
p.
5­
23).

Ponds
1B
and
1C
are
separated
from
Del
Am0
Boulevard
and
a
residential
area
to
the
south
by
a
double
row
of
fences
(ref.
5,
p.
5­
23).

Observations
made
during
boring
and
sampling
activities
indicate
that
the
waste
remaining
in
Ponds
1B
and
1C
is
a
fairly
uniform
fine­
grained
material
(clays
and
silts)
resembling
a
"clay­
like
sludge"
varying
in
color
from
gray
to
reddish­
black
(ref.
12,
p.
11).
This
waste
contains
hydrocarbons
with
high
polynuclear
aromatic
and
volatile
aromatic
content.
Naphthalene
is
the
predominant
polynuclear
aromatic
compound,
while
benzene
and
ethylbenzene
are
the
predominant
volatile
aromatic
compounds
(ref.
5,
p.
5­
25;
ref.
7,
p.
iii).

Source
Twe
The
source
type
for
Source
2
is
"buried
surface
impoundment"
(ref.
1,
Table
2­
5).

Source
Location
Source
2
is
located
in
the
portion
of
the
Del
Amo
site
that
was
formerly
occupied
by
the
styrene
manufacturing
plant.
Ponds
1B
and
IC
are
approximately
100
feet
north
of
Del
Amo
Boulevard
(ref.
5,
Plate
3.3;
ref.
6).,

19
SD­
Characterization
and
Containment
Source
2
Source
Containment
Release
to
Ground
Water
Source
2
has
no
liner
(ref.
5,
p.
3­
6).
Analytical
results
provide
evidence
of
vertical
hazardous
substance
migration
from
the
waste
in
Source
2
to
the
soil
immediately
beneath
the
ponds
(ref.
5,
pp.
5­
26,
s­
29,5­
30,5­
31,
Tables
5.5­
3
through
5.5­
16,
Figures
5.5­
1,5.5­
1'0).
A
ground
water
containment
factor
value
of
10
is
assigned
for
"evidence
of
hazardous
substance
migration
from
source
area"
(ref.
1,
Table
3­
2).

20
SD­
Hazardous
Substances
Source
2
2.4.1
Hazardous
Substances
Hazardous
Substance
Evidence
Reference
benzene
wastdsoil
sample
nos.%
11,
Table
5.2­
1,

S
148
S
172
p.
B­
11
p.
B­
12
ethylbenzene
S
124
p.
B­
13
wastesample
nos.%%
7,
Table2­
6
lB(
7.0)

lC(
7.0)

wastesample
nos.%%%
12,

wssoooo8
pp.
A3­
1,
A4­
56
sssooo24
pp.
A3­
1,
A4­
5,6
wss00011
SSSOOO30
thru
SSSOOO32
wastdsoil
sample
nos.%

S
148
S
172
S124
waste
sample
nos.%%

lB(
7.0)

lC(
7.0')

waste
sample
nos.%%%

wssoooo8
SSS00024andSSS00025
wss00011
SSSOOO30
thru
SSSOOO32
pp.
A3­
2,
A4­
56
pp.
A3­
2,
A4­
64
11,
Table
5.2­
1,

p.
B­
11
p.
B­
12
p.
B­
13
7,
Table
2­
6
12,

pp.
A3­
1,
A4­
57
pp.
A3­
1,
A4­
57
pp.
A3­
2,
A4­
57
pp.
A3­
2,
A4­
65
21
naphthalene
SD­
Hazardous
Substances
Source
2
waste/
soil
sample
nos.%
11,
Table
5.2­
1,

S
148
p.
B­
21
S
172
p.
B­
22
S
124
p.
B­
23
waste
sample
nos.%%%
12,

WSSOOOO8
pp.
A3­
1,
A4­
54
SSS00024
and
SSSOOO25
pp.
A3­
1,
A454
wss00011
pp.
A3­
2,
A4­
54
SSSOOO30
thru
SSSOOO32
pp.
A3­
2,
A4­
62
In
1984,
Dames
&
Moore,
under
contract
to
Ire11
&
Manella,
drilled
four
soil
borings
in
Source
2
(i.
e.,
borings
1­
B­
I
and
1­
B­
I1
in
Pond
1B;
and
borings
1­
C­
I
and
1­
C­
I1
in
Pond
1C)
to
characterize
the
fill
material
overlying
the
waste,
the
waste,
and
the
soil
beneath
the
waste
(ref.
11,
p.
4­
24,
Figure
4.3­
1).
Twelve
to
13
soil
andor
waste
samples
were
collected
from
each
boring
(49
total)
at
2.5­
foot
or
5­
fOOt
intervals
from
ground
surface
to
a
depth
of
45
feet
bgs
(ref.
11,
pp.
4­
26,4­
27,
Table
4.3­
2).
Of
the
49
samples,
.the
following
three
samples
consisting
of
a
combination
of
waste
and
soil
were
selected
for
chemical
analysis:
S148
from
boring
1­
B­
I
in
Pond
lB,
S172
from
boring
1­
B­
I1
in
Pond
lB,
and
S124
from
boring
1­
C­
I
in
Pond
1C
(ref.
11,
Tables
4.3­
2,5.2­
1,
Appendix
A,
pp.
A­
1
through
A­
4).
All
three
samples
were
analyzed
for
purgable
aromatics
using
EPA
Method
602
and
extractable
hydrocarbons
using
EPA
Method
610.
Analytical
results
indicated
the
presence
of
benzene,
ethylbenzene,
and
naphthalene
at
concentratiqns
up
to
140
mg/
kg,
3,500
mg/
kg,
and
4,420
mg/
kg,
respectively,
in
Pond
1B;
and
160
mg/
kg,
310
mgkg,
and
2,700
mgkg,
respectively,
in
Pond
1C
(ref.
11,
p.
5­
6,
Appendix
B,
pp.
B­
11
through
'B­
13,
B­
21
through
B­
23).

%%
In
1990,
Dames
&
Moore,
under
contract
to
G.
P.
Holdings,
Inc.,
Dow
Chemical
Comp&
y,
and
Shell
Oil
Company,
drilled
six
borings
in
Source
2
to
collect
samples
for
treatability
testing
(i.
e.,
borings
1B­
I,
1B­
2,
and
1B­
3
in
Pond
1B
and
borings
1C­
1,
1C­
2,
and
1C­
3
in
Pond
IC)
(ref.
5,
Table
5.5­
1,
Figure
5.5­
1;
Reference
7,
Appendix
D,
pp.
D­
1
through
D­
7).
Two
waste
samples,
which
were
collected
at
a
depth
of
7
feet
bgs,
were
analyzed
for
volatile
organic
compounds
using
EPA
Method
8240.
Analytical
results
indicated
the
presence
of
benzene
and
ethylbenzene
at
concentrations
of
580
mg/
kg
and
4,000
mgkg,
respectively,
in
Pond
1B;
and
140
mg/
kg
and
1,700
mgkg,
respectively,
in
Pond
1C
(ref.
7,
p.
2­
4,
Table
2­
6).

%%
c;
k
In
1992,
Dames
&
Moore,
under
contract
to
Shell
Oil
Company
and
Dow
Chemical
Company,
drilled
two
borings
in
Source
2
(i.
e.,
borings
SBL0004
and
SBL0005
in
Pond
IC)
as
part
of
a
waste
excavation
feasibility
study
(ref.
12,
p.
1,
Appendix
A,
Figure
A­
1).
Three
waste
samples
(WSSOOOOS,
SSSOOOO4,
and
SSSOOO25)
collected
from
boring
SBL0004
and
four
waste
samples
(WSSOOOl1,
SSSOOO30,
SSSOOO31,
and
SSSOOO32)
collected
from
boring
SBL0005
were
22
.
"
SD­
Hazardous
Substances
Source
2
analyzed
for
volatile
organic
compounds
using
EPA
Method
8240
and
for
polynuclear
aromatic
hydrocarbons
using
EPA
Method
8270
(ref.
12,
Appendix
A,
p.
A­
2,
Attachment
A3,
pp.
A3­
1,
A3­
2,
Attachment
A4,
pp.
A4­
54,
A4­
56,
A4­
57,
A4­
62,
A4­
64,
A4­
65).
Analytical
results
indicated
the
presence
of
benzene,
ethylbenzene,
and
naphthalene
at
concentrations
up
to
260
mglkg,
1,200
m@
g,
and
9,700
mglkg,
respectively,
in
the
waste
in
Pond
1C
(ref.
12,
Appendix
A,
Attachment
A4,
pp.
A4­
54,
A4­
56,
A4­
57).

The
hazardous
substances
associated
with
Source
2
include:

benzene
ethylbenzene
naphthalene
Other
hazardous
substances
are
associated
with
Source
2
(e.
g.,
toluene,
and
styrene)
(ref.
5,
p.
5­
25).
The
documentation
presented
above
is
limited
to
benzene,
ethylbenzene,
and
naphthalene
because
these
three
hazardous
substances
are
the
dominant
constituents
of
the
hydrocarbon
waste
remaining
in
Ponds
1B
and
1C
(ref.
7,
p.
iii).

23
SD­
Hazardous
Waste
Quantity
Source
2
2.4.2
Hazardous
Waste
Quantity
Tier
A:
Hazardous
Constituent
Ouantitv
Documentation
is
not
sufficient
to
determine
hazardous
constituent
quantity.

Hazardous
Constituent
Quantity
Value:
0
24
SD­
Hazardous
Waste
Quantity
Source
2
Tier
B:
Hazardous
Wastestream
Ouantitv
Documentation
is
not
sufficient
to
determine
hazardous
wastestream
quantity.

Hazardous
Wastestream
Quantity
Value:
0
25
SD­
Hazardous
Waste
Quantity
Source
2
Tier
C:
Volume
Documentation
is
not
sufficient
to
determine
the
volumes
of
Ponds
1B
and
1C.

26
Volume
Assigned
Value:
0
Tier
D:
Source
Area
SD­
Hazardous
Waste
Quantity
Source
2
A
1947
aerial
photograph
shows
the
surface
areas
of
Ponds
1B
and
1C
(ref.
11,
Figure
1.0­
1,
Table
4.3­
4).

Surface
Area
(ft2)

Pond
1B
Pond
IC
Total
22,040
21,600
43,640
Area
Value
(A):
43;
640
ft2
References:
1
1,
Figure
1
.O­
1,
Table.
4.3­
4
Area
Assigned
Value
(N13):
3,357
27
SD­
Hazardous
Waste
Quantity
Source
2
2.4.2
Source
Hazardous
Waste
Ouantitv
Based
on
Tier
D,
the
hazqdous
waste
quantity
associated
with
this
source
is
3,357.

Source
Hazardous
Waste
Quantity:
3,357
28
SD­
Characterization
and
Containment
Source
3
SOURCE
DESCRIPTION
2.2
Source
Characterization
Source
Description:
Source
3
­
Spillage
from
Historic
Crude
Benzene
Storage
Tank
Source
3
consists
of
spillage
from
a
historic
crude
benzene
storage
tank
that
was
located
in
the
northwest
corner
of
the
former
styrene
manufacturing
plant's
tank
farm.
The
tank
farm,
which
was
referred
to
as
the
2500
area
tank
farm,
consisted
of
17
large
cylindrical
aboveground
storage
tanks
and
several
smaller
tanks
(ref.
5,
p.
3­
5,
Plate
3­
1).
The
tanks
stored
crude
and
refined
products
associated
with
the
styrene
manufacturing
process,
including
benzene,
ethylbenzene,
toluene,
styrene,
polyethylbenzene,
propylbenzene,
butylbenzene,
and
fuel
oil
(ref.
5,
p.
3­
12,
Appendix
A,
p.
A­
29).
The
capacity
of
crude
benzene
storage
tank
was
at
least
500,000
gallons
(ref.
52,
p.
7­
4).

Aerial
photographs
and
site
history
documents
indicate
that
spillage
occurred
in
the
2500
area
during
transfer
of
the
contents
of
the
tanks
to
and
from
railroad
cars
and
trucks.
Aerial
photographs
show
tonal
contrasts
thar
may
represent
staining
in
the
2500
area
(ref.
5,
p.
3­
12,
Appendix
A,
pp.
A­
6,
A­
7,
Plate
A­
1).
Site
history
documents
refer
to
spills
which
occurred
during
transfer
operations.
For
example,
a
Request
for
Expenditures
(dated
February
7,
1968)
indicates
the
need
for
lighting
in
the
finished
styrene
tanks,
because
the
tanks
were
typically
filled
during
night
hours
and
overfilling
occurred
(ref.
5,
Appendix
A,
p.
A­
29).

Evidence
of
Spillage
from
the
Historic
Crude
Benzen.
e
Storage
Tank
An
area
of
non­
aqueous
phase
liquid
(NAPL)
accumulation
is
currently
located
proximal
to
the
historic
crude
benzene
storage
tank.
As
documented
below,
the
presence
of
this
NAPL
provides
evidence
of
spillage
from
the
tank,
based
on
the
location
of
the
NAPL
and
its
chemical
composition
(ref.
51,
p.
i,
Figure
ES­
1).

Location
of
the
NAPL
In
1990,
Hargis
+
Associates,
under
contract
to
the
Montrose
Chemical
Company,
constructed
a
monitoring
well
(MW­
20)
approximately
100
feet
southeast
of
the
historic
crude
benzene
storage
tank
(ref.
51,
p.
1,
Figure
3;
ref.
53).
Upon
completion,
NAPL
was
detected
floating
on
ground
water
in
the
well
(ref.
5
1,
p.
1).
NAPL
was
not
detected
in
monitoring
well
MW­
1,
which
is
located
approximately
175
feet
northwest
of
the
historic
location
of
the
crude
benzene
storage
tank;
monitoring
well
"­
27,
which
is
located
approximately
600
feet
southwest
of
the
historic
location
of
the
tank;
or
monitoring
wells
MW­
21
and
MW­
28,
which
are
located
approximately
775
feet
and
950
feet,
respectively,
southeast
of
the
historic
location
of
the
tank
(ref.
5
1,
pp.
1,
2,
12,
Figure
2).

In
October
1992,
Dames
&
Moore,
under
contract
to
the
Shell
Oil
Company
and
The
Dow
Chemical
Company,
installed
four
additional
monitoring
wells
(SWLOOO1
through
SWL0004),
11
temporarywell
points
(CWLOOO1
through
CWLOOl
l),
and
four
soil
borings
(SBL0009,
SBL0010,
SBLOOl
1,
and
SBL0017)
to
further
delineate
the
NAPL
(ref.
50,
Appendix
B,
pp.
B­
73
through
B­
84,
B­
120
through
B­
123,
Appendix
C,
Table
C­
1;
ref.
51,
pp.
3,
5,6,7,
Figures
15,
16;
ref.
53).
Floating
NAPL
was
observed
SD­
Characterization
and
Containment
Source
3
in
monitoring
wells
MW­
20
and
SWLO001,
and
temporary
well
points
CWLO00l
through
CWLOOO4,
CWL0006,
CWL0008,
and
CWL0009.
In
addition,
a
hydrophobic
hydrocarbon­
specific
dye
(Sudan
Red)
test
indicated
the
presence
of
NAPL
in
one
of
the
four
soil
borings
(SBL0017).
(ref.
51,
pp.
14,
15,
Figures
15,
16;
ref.
53).

In
May,
July,
and
August
1993,
Dames
&
Moore
drilled­
seven
additional
soil
borings
(SBL0049,
SBL0050,
SBL0068,
SBL0069,
SBL0070,
SBL0071,
and
SBL0073)
to
further
delineate
the
NAPL
(ref.
5,
p.
2­
18,
Figure
2.6­
2;
ref.
50,
Appendix
B,
pp.
B­
269
through
B­
276,
B­
345
through
B­
358,
B­
361
through
B­
363;
ref.
53).
NAPL
was
identified
in
one
of
the
seven
borings
(SBL0071),
using
the
Sudan
Red
test
(ref.
5,
pp.
2­
18,5­
20;
ref.
53).
Floating
NAPL
was
observed
in
monitoring
well
SWL0032,
which
was
installed
in
December
1993
(ref.
50,
p.
5­
1,
Appendix
C,
Table
C­
1
;
ref.
54,
Figure
1).

In
April
and
May
1994,
Dames
&
Moore
drilled
10
additional
soil
borings
(SBLO0085
through
SBL00094),
as
part
of
a
hydraulic
extraction
pilot
program
(ref.
53;
ref.
54,
pp.
1,2,
Figure
1).
NAPL
was
detected
in
the
saturated
zone
in
all
10
borings,
using
ultraviolet
light
and
Sudan
Red
tests
(ref.
50,
Appendix
B,
pp.
B­
429
through
B­
468;
ref.
53;
ref.
54,
p.
7;
ref.
55,
pp.
36,40,42,72,
119,
121,
123,
127,
129,
137,
143;
ref.
56,
pp.
34,
38,40,42,44,56,
114,
116,
128,
130,
132,
134,
136,
138,
140,
142,
144;.
ref.
57,
pp.
28,34,36,
38,40,42,44,48,
50,52,54,56,68,
111,
121,
125,
127,
129,
131,
133,
135,
137,
139,
143,
145,
147;
ref.
58,
pp.
26,28,38,40,42,44,46,48,52,
123,125,
127,
129,
131,
133,
135,
137,
139,
141,
149,
151;
ref.
59,
pp.
56,58,64,
144,
146,
152,
154,
156,
158,
164,
169,
171,
173,
175).
'

Based
on
the
presence
or
absence
of
NAPL
in
the
monitoring
wells,
temporary
well
points,
and
soil
borings
described
above,
the
lateral
extent
of
the
NAPL
has
been
estimated
to
range
from
14,300
to
17,500
square
feet
(ref.
50,
p.
5­
1;
ref.
51,
p.
13,
Figures
15,
16;
ref.
54,
Figure
1).
The
northwest
edge
of
NAPL
is
located
approximately
50
feet
southeast
of
the
historic
crude
benzene
storage
tank
(ref.
51,
p.
13,
Figure
16;
ref.
54,
Figure
1).

Chemical
Composition
of
the
NAPL
In
1992,
Dames
&
Moore
*collected
NAPL
samples
from
monitoring
well
MW­
20
and
two
temporary
wells
points
located
within
50
feet
of
monitoring
well
MW­
20
(CWL0006
and
CWL0009).
Physical
and
chemical
testing
of
these
samples
indicated
that
the
NAPL
is
composed
primarily
of
benzene
(90%)
with
lesser
quantities
of
toluene,
ethylbenzene,
and
styrene
(40%
total)
and
an
unidentified
C25
hydrocarbon
trace)
(ref.
51,
pp.
i,
12,
Tables
7,
11,
Figure
6).
The
low
concentrations
of
toluene,
ethylbenzene,
and
styrene
present
in
the
NAPL,
relative
to
benzene,
correlate
with
what
is
known
about
the
composition
of
the
crude
benzene
stock
that
was
historically
used
at
the
styrene
manufacturing
plant
(i.
e.,
the
stock.
contained
impurities)
(ref.
51,
p.
12).

In
addition
to
the
NAPL
investigations
presented
above,
soil
sampling
has
been
conducted
in
the
vadose
zone
beneath
the
historic
location
of
the
crude
benzene
storage
tank
and,
above
the
current
location
of
the
NAPL
(ref.
5,
pp;
2­
18,
Figure
5.4­
3).
The
analytical
data
from
these
soil
sampling
efforts
are
not
presented
as
evidence
of
spillage
from
the
tank
because
benzene
was
either
not
detected
or
detected
at
trace
concentrations
in
the
vadose
zone
(ref.
5,
Figure
5.4­
3).
The
absence
of
significant
benzene
contaminated
soil
is
inferred
to
be
due
to
natural
degradation
processes
that
have
occurred
in
an
aerobic
vadose
zone
soil
environment
since
the
benzene
was
released
(ref.
5,
p.
5­
22;
ref.
50,
p.
1­
14).
Based
on
the
time
period
..
­
30
SD­
Characterization
and
Containment
Source
3
during
which
the
styrene
manufacturing
plant
operated
(i.
e.,
1942
to
1969),
the
release
occurred
between
31
and
58
years
ago
(ref.
5,
p.
5­
22).

Source
Tvpe
The
source
type
for
Source
3
is
"other"
(ref.
1
,
Table
2­
5).

Source
Location
Spillage
from
the
historic
crude
benzene
storage
tank
is
currently
present
as
an
appr6ximately
14,300
to
17,500­
square­
foot
area
of
NAPL
accumulation,
50
feet
to
the
southeast
of
where
the
tank
was
located
in
the
nofihwest
portion
of
the
former
styrene
manufacturing
plant
(ref.
6;
ref.
50,
Figure
5.1­
1;
ref.
51,
p.^
13,
Figure
16;
ref.
54,
Figure
1).

Source
Containment
Release
to
Ground
Water
The
presence
of
NAPL
provides
evidence
of
hazardous
substance
migration
from
the
historic
crude
benzene
storage
tank
(ref.
5
1,
p.
13).
A
ground
water
containment
factor
value
of
10
is
assigned
for
"evidence
of
hazardous
substance
migration
from
source
area"
(ref.
1,
Table
3­
2).

31
SD­
Hazardous
Substances
Source
3
2.4.1
Hazardous
Substances
In
1992,
Dames
&
Moore,
under
contract
to
Shell
Oil
Company
and
The
Dow
Chemical
Company,
collected
NAPL
samples
from
monitoring
well
MW­
20
and
two
temporary
wells
located
within
50
feet
of
monitoring
well
MW­
20
(CWL0006
and
CWL0009).
Physical
and
chemical
testing
of
these
samples
indicated
that
the
NAPL
is
composed
primarily
of
benzene
(90%)
with
lesser
quantities
of
ethylbenzene,
toluene,
and
styrene
(40%
total)
and
an
unidentified
C25
hydrocarbon
trace
(ref.
51,
pp.
i,
12,
Tables
.7,

1
1,
Figure
6).

The
dominant
hazardous
substance
associated
with
Source
3
is:

benzene
32
SD­
Hazardous
Waste
Quantity
Source
3
2.4.2
Hazardous
Waste
Quantity
Tier
A:
Hazardous
Constituent
Ouantitv
C
(concentration
of
benzene
in
the
NAPL)
=
90percent
In
1992,
Dames
and
Moore,
under
contract
to
Shell
Oil
Company
and
The
Dow
Chemical
Company,
collected
NAPL
samples
from
monitoring
well
MW­
20
and
two
temporary
wells
located
within
50
feet
.of
monitoring
well
MW­
20
(CWL0006
and
CWL0009).
Physical
and
chemical
testing
of
these
samples
indicated
that
the
NAPL
is
composed
primarily
of
90
percent
benzene
(ref.
51,
pp.
i,
12,
Tables
7,
11,
Figure
6).

D
(density
of
benzene)
=
7.32
pounds
per
gallon
By
definition,
the
density
of
water
is
1.
The
weight
of
water
is
8.330
pounds
per
gallon.
The
density
of
benzene
is
0.8786
relative
to
water
(ref.
61).
Multiplying
the
weight
of
water
(8.330
pounds
per
gallon)
x
the
density
of
benzene
relative
to
water
(0.8786)
yields
the
density
of
benzene
(7.32
pounds
per
gallon).

V
(partial
volume
of
the
NAPL)
=
935
gallons
According
to
the
May
15,
1998
Final
Ground
water
Remedial
Investigation
(RI)
Report
for
the
Del
Am0
Study
Area,
the
NAPL
in
the
vicinity
of
monitoring
well
MW­
20
extends
laterally
over
an
area
of
approximately
'17,500
square
feet
(ref.
50,
p.
5­
1).
It
is
limited
to
the
saturated
zone,
occurring
as
isolated
blobs
in
a
smear
zone
that
extends
from
the
water
table,
at
approximately
60
feet
bgs,
to
30
feet
below
the
water
table
(ref.
50,
pp.
4­
1,
6­
20).
This
mode
of
occurrence
is
consistent
with
conditions
that
can
be
expected
after
a
NAPL,
which
in
this
case
is
a
NAPL
that
is
lighter
than
water,
has
migrated
through
the
vadose
zone,
intercepted
the
water
table,
and
then
been
influenced
by
a
rising
water
table.
Ground
water
levels
have
been
rising
in
the
vicinity
of
the
Del
Am0
site
since
1965,
most
likely
as
a
result
of
controls
that
were
placed
on
ground
water
pumping
as
part
of
the
adjudication
of
the
West
Coast
Basin
in
1961
(ref.
50,
p.
4­
1).

The
vertical
and
lateral
components
of
the
Tier
A'
volume
calculations
presented
below
are
based
on
only
that
portion
of
the
NAPL
that
has
received
detailed
inspection
and
analysis.
This
portion,
which
is
defined
by
eight
of
the
10
soil
borings
that
Dames
&
Moore
drilled
in
1994
(SBL00086
through
SBL0092
and
SBL0094),
represents
3.8
percent
of
the
estimated
total
lateral
extent
of
the
NAPL
(i.
e.,
657
square
feet
of
the
estimated
total
17,500
square
feet)
(ref.
53).

Vertical
Component
of
Tier
A
Volume
Calculations
During
the
1994
NAPL
investigation,
Dames
&
Moore
collected
continuous
core
from
ground
surface
to
a
depth
of
90
feet
bgs
at
each
of
10
soil
boring
locations
(SBLOOO85
through
SBL00094
(ref.
53;
ref.
54,
pp.
1,
2,
Figure
1).
Ultraviolet
light
and
Sudan
Red
tests
were
used
to
identify
the
presence
of
NAPL
in
each
continuous
core
(ref.
54,
p.
7).
Dean­
Stark
tests
for
effective
porosity
and
relative
pore
fluid
saturation
(water
and
NAPL)
were
then
performed
on
123
plug
samples
(1
inch,
diameter
by
0.5­
inch
long
cylinders)
selected
from
core
intervals
that
contained
NAPL,
as
well
as
from
core
intervals
that
did
not
contain
NAPL
(ref.
60,
pp.
7,
8,
13).

"

33
SD­
Hazardous
Waste
Quantity
Source
3
As
presented
in
the
table
below,
the
effective
porosity
and
relative
pore
fluid
saturation
data
from
105
of
the
123
plugs
(i.
e.,
the
data
from
all
plugs
from
borings
SBL0086
through
SBL0092
and
SBL0094)
were
used
to
determine
the
total
vertical
length
of
NAPL
(0.19
feet)
occupying
the
pore
spaces
in
a
18.9­
foot
thick
portion
of
the
smear
zone.
The
average
length
of
the
sampled
intervals
from
the
eight
borings
was
multiplied
by
the
average
effective
porosity
of
the
105
plugs
and
then
multiplied
by
the
average
pore
fluid
saturation
of
the
105
plugs
to
obtain
the
total
vertical
length
of
NAPL
in
the
pore
spaces
of
the
105
plugs.
The
remaining
18
plugs
were
collected
from
borings
SBL0085
and
SBL0093
(ref.
60,
Table
4).
As
,

discussed
previously
in
Section
2.2
(Source
Characterization),
NAPL
was
identified
in
these
two
borings
using
ultraviolet
light
and
Sudan
Red
tests
(ref.
55,
pp.
36,40,42,72;
ref.
59,
pp.
56,58,
64,
158,
164,
169,
171,
173,
175).
However,
NAPL
was
not
identified
in
any
of
the
plugs
that
were
subjected
to
Dean­
Stark
tests
(ref.
60,
Table
4).

34
\
h
m
m
W
2
oo
0
2
m
r­
oo
0
0
­1
rn
m
M
'G
c
0
.­
m
W
m
0
vi
2
m
m
0
s
w
M
'C
c
0
._
m
m
\4
F:

0
m
W
u!

N
z
vi
W
3
2
w
r­

0
2
vi
m
m
0
2
3
0
2
2
0
W
W
N
0
m
s
%
0
c?
­
r­

*
0
m
m
s
VI
0
d
SD­
Hazardous
Waste
Quantity
Source
3
Lateral
Component
of
Tier
A
Volume
Calculations
When
a
graph
paper
overlay
with
a
scale
of
20
squares
per
inch
is
placed
over
the
area
defined
by
borings
SBLOO86
through
SBL0092
and
SBL0094
in
the
figure
in
Reference
53,657
squares
fall
within
the
boundaries.
Since
the
scale
of
the
figure
in
Reference
53
is
20
feet
per
inch,
each
square
on
the
graph
paper
represents
1
square
foot.
Therefore,
the
area
defined
by
borings
SBL0086
through
SBL0092
and
SBL0094
is
approximately
657
square
feet.

Tier
A
Volume
Calculations
The
average
vertical
feet
of
NAPL
(0.19
feet)
multiplied
by
the
area
defined
by
borings
SBL0086
through
SBL0092
and
SBL0094
(657
square
feet)
produces
125
cubic
feet.
Multiplying
125
cubic
feet
by
the
standard
conversion
factor
of
7.48
gallons
per
cubic
foot
yields
a
NAPL
volume
of
935
gallons.

HCQ
(Hazardous
Constituent
Quantity)
=
C
x
D
x
V
=
6,160pounds
of
benzene
Multiplying
C
(0.90)
by
D
(7.32
pounds
per
gallon)
by
V
(935
gallons)
yields
6,160
pounds
of
benzene
in
a
portion
of
the
NAPL.

Hazardous
Constituent
Quantity
Value:
6,160
41
SD­
Hazardous
Waste
Quantity
Source
3
Tier
B:
Hazardous
Wastestream
Quantity
Documentation
is
not
sufficient
to
document
hazardous
wastestream
quantity.

Hazardous
Wastestream
Quantity
Value:
0
42
Tier
C:
Volume
SD­
Hazardous
Waste
Quantity
Source
3
As
presented
in
the
Tier
A
calculations,
the
volume
of
NAF'L
in
the
portion
of
the
NAPL.
that
is
defined
by
~

borings
SBL0086
through
SBL0092
and
SBL0094
is
935
gallons.
There
are
200
gallons
in
1
cubic
yard.
Dividing
935
gallons
by
200
gallons
yields
4.68
cubic
yards.
Dividing
4.68
cubic
yards
by
the
Tier
C
divisor
for
the
source
type
"other"
(2.5)
yields
a
volume
assigned
value
of
1.87
(ref.
1,
Table
2­
5)..

Volume
Assigned
Value:
1.87
43
SD­
Hazardous
Waste
Quantity
Source
3
Tier
D:
Source
Area
Tier
D
cannot
be
calculated
for
the
source
type
"other,"
because
this
source
type
is
not
included
in
the
list
of
source
types
in
the
Tier
D
sect&
of
HRS
Table
2­
5
(ref.
1,
Table
2­
5).

Area
Assigned
Value:
0
44
.
SD­
Hazardous
Waste
Quantity
Source
3
Source
Hazardous
Waste
Quantity
Based
on
Tier
A,
the
hazardous
waste
quantity
associated
with
this
source
is
6,160.

Source
Hazardous
Waste
Quantity:
6,160
45
SUMMARY
OF
SOURCE
DESCRIPTIONS
Source
Air
Source
Hazardous
Waste
Ground
Water
Surface
Water
GasParticulate
Number
Quantity
Value
Containment
Containment
Containment
1
728
.
.
10
not
scored
not
scored
2
10
not
scored
not
3
6,160
10
not
scored
Sources
Not
Included
in
Scoring
In
addition
to
the
three
sources
that
are
quantified
in
this
documentation
record,
the
May
15;
1998
Final
Ground
Water
RI
Report
identified
the
following
10
source
areas
of
ground
water
contamination
on
the
historic
Del
Am0
synthetic
rubber
manufacturing
property
(ref.
6;
ref.
50,
Figure
5.3­
5):

1.

2.
3.

4.
5.
6.
7.
8.
9.
10.
Cyclohexane
tanks
associated
with
the
former
copolymer
plant
in
the
northern
portion
of
the
site,
Onsite
"pits
and
trenches"
in
the
former
copolymer
plant
area,
Volatile
organic
compound
(VOC)
tanks
associated
with
the
former
styrene
finishinghenzene
purification
unit,
VOC
tanks
and/
or
underground
pipelines
associated
with
the
former
styrene
finishing
unit,
Tank
f
p
n
in
the
former
styrene
plant
area,
VOC
storage
tanks
associated
with
the
former
ethylbenzene
production
unit
#1,
VOC
storage
tanks
associated
with
the
former
ethylbenzene
production
unit
#2,
Utility
@nks
in
the
former
styrene
plant
area,
Underground
benzene
pipeline
in
the
southeast
portion
of
the
site,
and
Laboratory
underground
pipelines
in
the
former
butadiene
plant
area
in
the
eastern
portion
of
the
site.

These
source
areas
were
identified
based
on
two
or
more
of
the
following
lines
of
evidence:
observation
of
NAPL
in
a
well
or
boring;
water
table
analytical
data
indicating
compound
concentrations
elevated
relative
to
surrounding
monitoring
locations;
historical
information
indicating
the
presence
of
facilities
where
large
volumes
of
chemicals
were
stored,
processed,
or
disposed
of;
and
shallow
soil
gas
data
indicating
elevated
concentrations
of
VOCs
(ref.
50,
p.
5­
20).

46
GW­
General
3.0
GROUND
WATER
MIGRATION
PATHWAY
3.0.1
GeneralConsiderations
The
Del
Amo
site
is
located
in
the
West
Coast
Basin
of
the
coastal
plain
of
Los
Angeles
County,
California
(ref.
15,
p.
1,
Plates
1
and
2).
The
following
unsaturated
soil
and
hydrogeologic
units,
in
descending
order,
have
been
identified
beneath
the
site:
recent
Playa
deposits,
Palos
Verdes
sand,
upper
Bellflower,
Bellflower
sand,
lower
Bellflower,
Gage,
Gage­
Lynwood,
Lynwood,
unnamed,
and
Silverado.
A
description
of
each
of
these
units
is
presented
below.
Characterization
of
the
first
eight
units
is
based
on
the
lithologic,
physical
parameter,
and
hydraulic
parameter
data
that
were
obtained
during
the
Montrose
RI
field
work
and
the
Del
Am0
RI
field
work.
The
Montrose
site
is
located
approximately
600
feet
west
of
the
300­
acre
Del
Am0
site
(ref.
5,
Figure
1.4­
1).
Between
1985
and
1991,
as
part
of
the
Montrose
RI,
Hargis
+
Associates
completed
121
soil
borings,
17
exploratory
borings,
and
91
monitoring
wells
on
and
in
the
vicinity
of
the
Montrose
and
Del
Amo
sites
(ref.
16,
pp.
4­
2
and
4­
12,
Tables
2.1,
2.2,2.3,2.5,
and
4.1,
Figures
4.4
and
4.9).
In
1993,
as
part
of
the
Del
Am0
RI,
Dames
&
Moore
completed
23
soil
borings,
37
temporary
well
points,
26
temporary
piezometers,
and
19
monitoring
wells
on
the
Del
Am0
Facility
site
(ref.
5,
pp.
1­
1,2­
6,2­
7,
Table
2.9­
2,
Figure
2.2­
1).
Characterization
of
the
lower
two
units
(i.
e.,
unnamed
and
Silverado)
is
based
on
the
findings
presented
in
the
1961
State
of
California
Department
of
Water
Resources
report,
Planned
Utilization
of
the
Ground
Water
Basins
of
the
Coastal
Plain
of
Los
Angeles
County
(ref.
15).

Stratum
1
(shallowest)

Stratum
Name:
Recent
Playa
Deposits
Description:
As
presented
in
the
October
1992
Montrose
RT
report,
recent
Playa
deposits
comprise
the
shallowest
geologic
unit
in
the
unsaturated
zone
(ref.
16,
Figure
2.6).
These
deposits
underlie
suficial
soils
and
fill
material.
The
unit
is
relatively
flat
lying
and
laterally
continuous.
The
Playa
deposits
consist
of
dark
brown
to
light
olive­
brown
silt,
clayey
silt,
or
clay,
as
well
as
clayey
sand,
sandy
silt,
or
sandy
clay.
The
contact
between
Playa
deposits
and.
the
underlying
Palos
Verdes
sand
is
gradational
and
characterized
by
an
increase
in
sand
content
from
a
silt
to
a
sand.
The
lower
contact
of
the
Playa
deposits
occurs
at
depths
ranging
from
22
feet
bgs
to
30
feet
bgs
(ref.
16,
pp.
4­
2,4­
5,
and
4­
6).

Stratum
2
,

Stratum
Name:
Palos
Verdes
Sand
Description:
As
presented
in
the
1992
Montrose
RI
report,
late
Pleistocene
marine
deposits,
which
are
also
referred
to
as
the
Palos
Verdes
sand,
underlie
the
Playa
deposits
in
the
unsaturated
zone
(ref.
16,
Figure
2.6).
The
Palos
Verdes
sand
unit
is
flat
lying
and
laterally
continuous.
It
consists
of
light
olive­
brown,
fine­
grained
sand,
and
silty
sand.
The
basal
portion
of
the
Palos
Verdes
sand
is
characterized
by
fossiliferous
sand
that
is
dense
and
well
cemented.
This
fossiliferous
sand
marks
the
contact
between
the
Palos
Verdes
sand
and
the
underlying
upper
Bellflower
unit.
The
lower
contact
of
the
Palos
Verdes
sand
occurs
at
depths
ranging
from
40
feet
bgs
to
49
feet
bgs
(ref.
16,
pp.
4­
2
and
4­
6).

"

47
GW­
General
Stratum
3
Stratum
Name:
Upper
Bellflower
Aquifer
Description:
As
presented
in
the
1992
Montrose
RI
report,
the
upper
Bellflower
underlies
the
Palos
Verdes
sand
(ref.
16,
Figure
2.6).
The
upper
Bellflower
is
relatively
flat
lying
and
laterally
continuous.
It
consists
of
interbedded,
micaceous,
olive­
brown
sand,
silty
sand,
silt
and
clay.
The
upper
portion
of
this
unit
is
unsaturated,
while
ground
water
occurs
in
the
bottom
portion
(ref.
16,
pp.
4­
6
and
4­
7).
Hargis
+
Associates
had
installed
30
ground
water
monitoring
wells
in
the
upper
Bellflower
by
November
1991
(ref.
16,
p.
4­
17,
Table
4.1
1).
Based
on
October
1991
water
level
measurements,
ground
water
flow
direction
tends
toward
the
southeast
(ref.
16,
p.
4­
18,
Figure
4.15).
The
contact
between
the
upper
Bellflower
and
the
underlying
Bellflower
sand
is
gradational.
The
contact
has
no
distinct
marker
beds
and
is
generally
identified
by
a
decrease
in
silt
interbeds
with
depth
or
by
an
increase
in
resistivity
with
depth.
The
base'of
the
upper
Bellflower
ranges
in
depth
from
approximately
47
feet
bgs
to
129
feet
bgs
(ref.
16,
p.
4­
15).

The
upper
Bellflower
is
considered
an
aquifer
for
HRS
purposes
because
the
State
of
California
Regional
Water
Quality
Control
Board
(RWQCB),
Los
Angeles
Region,
has
determined
that
all
ground
water
units
in
the
vicinity
of
the
Del
Am0
site
are
to
be
considered
potential
sources
of
drinking.
water
pursuant
to
State
Water
Resources
Control
Board
Resolution
88­
63
(i.
e.,
ground
water
is
considered
drinking
water
unless
the
total
dissolved
solids
(TDS)
>
3,000
milligrams
per
liter
(mg/
l),
deliverability
e
200
gallons
per
day,
or
pre­
existing
contamination
is
present
that
cannot
reasonably
be
treated)
(ref.
16,
p.
4­
24;
Reference
17,
p.
2).
In
May
1990,
constant
discharge
tests
were
conducted
at
five
monitoring
wells
screened
in
the
upper
Bellflower
(MW­
13,
MW­
15,
MW­
17,
MW­
25,
and
MW­
26).
Constant
discharge
rates
ranged
from
1.2
gallons
per
minute
(1,728
gallons
per
day)
to
12.6
gallons
per
minute
(18,144
gallons
per
day)
(ref.
19,
pp.
4
and
5,
Table
2,
Figure
1).
During
the
period
from
May
1985
through
October
1991,
inorganic
water
quality
was
assessed
in
29
monitoring
wells
screened
in
the
upper
Bellflower
(MW­
01
through
MW­
19
and
MW­
21
through
MW­
30)
during
initial
ground
water
sampling
of
each
well,
which
was
conducted
shortly
after
the
well
was
installed
(ref.
15,
p.
4­
21,
Figure
4.9,
Appendix
H,
Table
H­
I).
The
TDS
concentrations
ranged
from
110
mg/
l
to
13,740,000
mg/
l
with
a
concentration
of
3,000
mgA
being
exceeded
in
only
four
of
the
29
wells
(MW­
02,
MW­
05,
MW­
06,
and
MW­
07)
(Reference
16,
Appendix
H,
Table
H­
I).
Monitoring
wells
MW­
02,
MW­
05,
MW­
06,
and
MW­
07
are
on
the
Montrose
site'
in
or
near
the
central
process
area
where
dichlorodiphenyltrichloroethane
(DDT)
was
historically
manufactured
(ref.
16,
pp.
ES­
1
and
4­
23,
Figure
4.9).

Stratum
4
Stratum
Name:
'Bellflower
Sand
Aquifer
Description:
As
presented
in
the
October
1992
Montrose
RI
report,
the
Bellflower
sand
underlies
the
upper
Bellflower
aquifer
(ref.
16,
Figure
2.6).
The
Bellflower
sand
consists
of
fine­
to
coarse­
grained
sand
that
generally
coarsens
with
depth.
Thirty­
three
ground
water,
monitoring
wells
had
been
installed
in
the
Bellflower
sand
by
November
1991
(ref.
16,
p.
4­
24,
Figure
4.9).
The
ground
water
flow'direction
tends
toward
the
southeast
to
east­
southeast
(ref.
16,
p.
4­
26,
Figure
4.18).
The
contact
between
the
Bellflower
sand
and
the
underlying
Lower
Bellflower
stratum
is
a
distinct
sand
or
silt
that
ranges
in
depth
from
approximately
99
feet
bgs
to
146
feet
bgs
(ref.
16,
p.
4­
25).
In
the
October
1993
Del
Amo
RI
report,
the
Bellflower
sand
stratum
is
referred
to
as
the
middle
Bellflower.

L
9­

48
GW­
General
According
to
this
report,
the
lithologic
top
of
the
middle
Bellflower
occurs
at
an
average
depth
of
80
feet
bgs
and
the
base.
occurs
at
an
average
depth
of
145
feet
bgs
(ref.
5,
p.
4­
5,
Figure
4.1­
3).

The
Bellflower
sand
is
considered
an
aquifer
for
HRS
purposes
because
the
RWQCB,
Los
Angeles
Region,
has
determined
that
all
ground
water
units
in
the
vicinity
of
the
Del
Am0
site
are
to
be
considered
potential
sources
of
drinking
water
pursuant
to
State
Water
Resources
Control
Board
Resolution
88­
63
(i.
e.,
ground
water
is
considered
drinking
water
unless
the
TDS
>
3,000
mfl,
deliverability
c
200
gallons
per
day,
or
pre­
existing
contamination
is
present
that
cannot
reasonably
be
treated)
(ref.
16,
p.
4­
30;
ref.
17,
p.
2;
ref.
18,
p.
2).
In
May
1990,
constant
discharge
tests
were
conducted
at
six
monitoring
wells
screened
the
Bellflower
sand
(BF­
5,
BF­
7,
BF­
9,
BF­
11,
BF­
13,
and
BF­
15).
Constant
discharge
rates
ranged
from
19.9
gallons
per
minute
(28,656
gallons
per
day)
to
85.8
gallons
per
minute
(123,552
gallons
per
day)
(ref.
19,
pp.
4
and
5,
Table
2,
Figure
1).
During
the
period
of
January
1987
through
October
1991,
inorganic
water
quality
was
assessed
in
33
monitoring
wells
screened
in
the
Bellflower
sand
(BF­
01
through
BF­
33)
during
initial
ground
water
sampling
of
each
well,
which
was
conducted
shortly
after
the
well
was
installed
(ref.
16,
p.
4­
29,
Figure
4.9,
Appendix
H,
Table
H­
1).
The
TDS
concentrations
in
ground
water
samples
collected
from
the
33
wells
ranged
from
346
mgA
to
1,470
mg/
l,
except
in
monitoring
well
BF­
13,
which
had
a
concentration
of
5,600
mg/
l
(ref.
16,
p.
4­
30,
Appendix
H,
Table
H­
1).

Stratum
5
Stratum
Name:
Lower
Bellflower
Aquitard
Description:
As
presented
in
the
October
1992
Montrose
RI
report,
the
lower
Bellflower
underlies
the
Bellflower
sand
(ref.
16,
Figure
2.6).
The
lower
Bellflower
is
heterogenous
and
consists
of
silt
of
varying
plasticity
as
well
as
clayey
sandy
silt,
fine­
grained
silty
sand,
and
sand.
There
are
no
ground
water
monitoring
wells
screened
in
the
lower
Bellflower.
The
contact
between
the
lower
Bellflower
and
the
underlying
Gage
unit
is
a
moderately
well­
defied
silt
to
fine­
grained
sand
that
ranges
in
depth
from
approximately
124
feet
bgs
to
171
feet
bgs
(ref.
16,
p.
4­
32).

As
presented
in
the
October
1993
Del
Amo
RI
report,
the
lower
Bellflower
has
a
predominance
of
muddy
lithotypes.
Its
lithologic
top
occurs
at
an
average
depth
of
140
feet
bgs
and
the
base
occurs
at
an
average
depth
of
170
feet
bgs
(ref.
5,
p.
4­
5,
Figure
4.1­
3).

Stratum
6
Stratum
Name:
Gage
Aquifer
Description:
As
presented
in
the
October
1992
Montrose
RI
report,
the
Gage
underlies
the
lower
Bellflower
(ref.
16,
Figure
2.6).
The
Gage
typically
consists
of
fine­
grained
sand
with
a
little
silt
that
grades
to
a
silty
sand
near
the
base
of
the
aquifer.
Twenty­
one
ground
water
monitoring
wells
had
been
installed
in
the
Gage
by
November
1991.
Nineteen
of
these
wells
(G­
1
through
G­
19)
are
completed
in
the
upper
portion
of
the
unit,
and
two
(LG­
1
and
LG­
2)
are
completed
in
the
lower
portion
(ref:
16,
p.
4­
35,
Figure
4.21).
The
contact
between
the
Gage
and
the
underlying
Gage­
Lynwood
stratum
is
gradational
and
is
characterized
by
intermittent
interbedding
of
silt
and
silty
sand.
This
contact
ranges
in
depth
from
approximately
180
feet
bgs
to
221
feet
bgs
(ref.
16,
pp.
4­
34).

49
GW­
General
As
presented
in
the
October
1993
Del
Amo
RI
report,
the
lithologic
top
of
the
Gage
occurs
at
an
average
depth
of
170
feet
bgs
and
the
base
occurs
at
an
average
depth
of
240
feet
bgs
(ref.
5,
p.
4­
5,
Figure
4.1­
3).

The
Gage
is
considered
an
aquifer
for
HRS
purposes
because
the
RWQCB,
Los
Angeles
Region,
has
determined
that
all
ground
water
units
in
the
vicinity
of
the
Del
Amo
site
are
to
be
considered
potential
sources
of
drinking
water
pursuant
to
State
Resources
Control
Board
Resolution
88­
36
(i.
e.,
ground
water
is
considered
drinking
water
unless
the
TDS
>
3,000
mg/
l,
deliverability
<
200
gallons
per
day,
or
pre­
existing
contamination
is
present
that
cannot
be
reasonably
treated)
(ref.
16,
p.
4­
39;
Reference
17,
p.
2;
ref.
18.,
p.
2).
In
May
and
June
1990,
constant
discharge
tests
were
conducted
at
four
monitoring
wells
screened
in
the
Gage
aquifer
(G­
5,
G­
11,
G­
13,
and
LG­
2).
Constant
discharge
rates
ranged
from
65.5
gallons
per
minute
(94,320
gallons
per
day)
to
82.6
gallons
per
minute
(1
18,944
gallons
per
day)
(ref.
19,
pp.
4
and
6,
Table
2,
Figure
1).
During
the
period
from
January
1987
through
October
1991,
inorganic
water
quality
was
assessed
in
21
monitoring
wells
screened
in
the
Gage
(G­
01
through
G­
19,
LG­
01,
and
LG­
02)
during
initial
ground
water
sampling
of
each
well,
which
was
conducted
shortly
after
the
well
was
installed
(ref.
16,
p.
4­
38,
Figure
4.9,
Appendix
H,
Table
H­
1).
The
TDS
concentrations
in
ground
water
samples
collected
from
the
21
wells
ranged
from
200
mg/
l
to
520
mg/
l
(ref.
16,
p.
4­
39,
Appendix
H,
Table
H­
1).

stratum
7
Stratum
Name:
Gage­
Lynwood
Aquitard
Description:
As
presented
in
the
October
1992
Montrose
RI
report,
the
Gage­
Lynwood
underlies
the
Gage
(ref.
16,
Figure
2.6).
The
Gage­
Lynwood
consists
of
silt,
sandy
silt,
and/
or
clayey
silt
interbedded
with
fine­
grained
sand.
There
are
no
ground
water
monitoring
wells
screened
in
this
stratum.
The
contact
between
the
Gage­
Lynwood
and
the
underlying
Lynwood
is
distinct
because
of
the
contrast
between
the
silt
in
the
Gage­
Lynwood
and
the
fine­
to
coarse­
grained
sand
in
the
Lynwood.
This
contact
ranges
in
depth
from
approximately
212
feet
bgs
to
258
feet
bgs
(ref.
16,
p.
4­
40).

In
the
October
1993
Del
Am0
RI
report,
the
Gage­
Lynwood
stratum
is
referred
to
as
the
El
Segundo.
According
to
this
report,
the
lithologic
top
of
the
El
Seendo
occurs
at
an
average
depth
of
240
feet
bgs.
The
depth
of
the
base
of
the
El
Segundo
is
not
designated,
since
it
was
not
reached
during
the
Phase
I
RI
investigations
(ref.
5,
p.
4­
5,
Figure
4.1­
3).

Stratum
8
Stratum
Name:
Lynwood
Aquifer
Description:
The
Lynwood
underlies
the
Gage­
Lynwood
(ref.
16,
Figure
2.6).
The
upper
20
feet
of
the
Lynwood
consists
of
fine
to
coarse
grained
sand.
This
sand
is
frequently
underlain
by
as
much
as
8
feet
of
silt
or
clay
of
varying
plasticity.
Approximately
10
to
30
feet
of
well­
graded
sand,­
gravelly
sand,
and
sandy
gravel
with
some
silty
sand
interbeds
underlie
the
top
20
to
30
feet
of
the
Lynwood.
Seven
ground
water
monitoring
wells
had
been
installed
in
the
Lynwood
by
November
1991
(ref.
16,
p.
4­
41
and
4­
42,
Figure
4.9).
The
ground
water
flow
direction
trends
toward
the
southeast
(Reference
16,
p.
4­
43,
Figure
4.23).
The
Lynwood
reaches
its
maximum
thickness
of
200
feet
at
a
location
approximately
3
miles
southeast
of
the
Del
Am0
site
(ref.
,15,
p.
133,
Plate
19B).
..

/
GW­
General
The
Lynwood
is
considered
an
aquifer
for
HRS
purposes
because
the
RWQCB,
Los
Angeles
Region,
has
determined
that
all
ground
water
units
in
the
vicinity
of
the
Del
Am0
site
are
to
be
considered
potential
sources
of
drinking
water
pursuant
to
State
Water
Resources
Control
Boakd
Resolution
88­
63
(i.
e.,
ground
water
is
considered
drinking
water
unless
the
TDS
>
3,000
mgA,
deliverability
e
200
gallons
per
day,
or
pre­
existing
contamination
is
present
that
carhot
reasonably
be
treated)
(ref.
16,
pp.
4­
46
and
4­
48;
ref.
17,
p.
2;
ref.
18,
p.
2).
In
May
1990,
a
constant
discharge
test
was
conducted
at
one
monitoring
well
screened
in
the
Lynwood
aquifer
(LW­
3).
The
constant
discharge
rate
was
65.6
gallons
per
minute
(94,464
gallons
.
per
day)
(ref.
19,
pp.
4
and
6,
Table
2,
Figure
1).
During
the
period
from
October
1989
through
October
1991,
inorganic
water
quality
was
assessed
in
seven
monitoring
wells
screened
in
the
Lynwood
(LW­
01
through
LW­
07)
during
initial
ground
water
sampling
of
each
well,
which
was
conducted
shortly
after
the
wells
were
installed
(ref.
16,
p.
4­
45,
Figure
4.9,
Appendix
H,
Table
H­
1).
The
TDS
concentrations
in
ground
water
samples
collected
from
the
seven
wells
.ranged
from
230
mg/
i
to
296
mgA
(ref.
16,
p.
4­
46,
Appendix
H,
Table
H­
1).
In
addition,
currently
operating
drinking
water
wells
within
4
miles
of
Sources
1
and
2
are
screened
partially
or
wholly
in
the
Lynwood.
For
example,
Dominguez
Water
Corporation
Well
75A,
which
is
a
drinking
water
well
located
3.5
miles
from
the
Del
Am0
site,
is
screened
at
the
following
intervals:
210
feet
to
290
feet
bgs,
330
feet
to
440
feet
bgs,
and
480
feet
to
550
feet
bgs
(ref.
20,
p.
5;
ref.
32).

stratum
9
Stratum
Name:
Unnamed
Aquitard
Description:
An
unnamed
stratum
that
is
approximately
100
feet
thick
underlies
the
Lynwood
(ref.
15,
Plate
6C).

Stratum
10
(deepest)

Stratum
Name:
Silverado
Aquifer
Description:
The
Silverado
underlies
the
unnamed
unit.
The
Silverado
is
composed
primarily
of
fine
to
coarse­
grained
sands
and
gravels.
These
highly
permeable
marine
deposits
reach
a
maximum
thickness
of
500
feet
in
the
West
Coast
Basin
(ref.
15,
p.
134).
The
Silverado
is
considered
an
aquifer
for
HRS
purposes
because
the
RWQCB,
Los
Angeles
Region,
has
determined
that
all
ground
water
units
in
the
vicinity
of
the
Del
Am0
Facility
site
are
to
be
considered
potential
sources
of
drinking
water
(ref.
17,
p.
2).
In
addition,
currently
operating
drinking
water
wells
within
4
miles
of
Sources
1
and
2
are
screened
partially
or
wholly
in
the
Silverado.
For
example,
Dominguez
Water
Corporation
Well
77,
which
is
a
drinking
water
well
located
3.6
miles
from
the
Del
Am0
site,
is
screened
at
t€
ie
following
interval:
558
feet
to
920
feet
bgs
(ref.
20,
p.
5;
ref.
32).

3.0.1.2.1
Aquifer
Interconnections
Ground
water
sampling
data,
discussed
below,
show
that
hazardous
substances
have
migrated
from
the
Upper
Bellflower
aquifer
down
to
the
Lynwood
aquifer
through
the
other
listed
aquifers.
According
to
the
HRS,
these
four
aquifers
can
be
combined
into
one
aquifer
for
scoring
purposes
(ref.
1,
Section
3.0.1.2.1).
Also
documented
below,
the
aquitard
between
the
Lynwood
and
Silverado
aquifers
is
not
laterally
continuous
within
2
miles
of
the
site.
For
this
reason,
the
four
uppermost
aquifers,
already
combined,
and
"

51
GW­
General
the
Silverado
can
be
considered
one
aquifer
for
scoring
purposes
(ref.
1,
Section
3.0.1.2.1).
Ground
Water
Sampling
Data
Analytica1,
data
from
ground
water
sampling
events
conducted
for
the
Montrose
RI
and
post­
RI
monitoring
programs
indicate
the
presence
of
chlorobenzene
and
para­
chlorobenzene
sulfonic
acid
(p­
CBSA)
in
monitoring
wells
screened
solely
in
the
upper
Bellflower
aquifer,
monitoring
wells
screened
solely
in
the
Bellflower
sand
aquifer,
monitoring
wells
screened
solely
in
the
Gage
aquifer,
and
monitoring
wells
screened
solely
in
the
Lynwood
aquifer.
Along
with
chloral
and
sulfuric
acid,
chlorobenzene
was
a
principal
raw
material
in
the
historic
production
of
DDT
at
the
Montrose
facility.
Chlorobenzene
and
p­
CBSA
were
the
two
most
widespread
compounds
detected
in
ground
water
during
the
Montrose
RI
(ref.
16,
pp.
ES­
1
and
ES­
13).
The
downward
migration
of
chlorobenzene
and
p­
CBSA
may
have
occurred
in
response
to
the
vertical
downward
gradients
that
have
been
reported
between
the
upper
Bellflower,
Bellflower
sand,
Gage,
and
Lynwood
aquifers
(ref.
16,
p.
6­
25
and
6­
33;
ref.
23,
pp.
2
and
3).
Analytical
results
from
selected
sampling
events
are
presented
in
the
table
below.
Results
indicating
that
the
analyte
was
not
detected
above
the
sample
quantitation
limit
are
not
included
in
this
table.
Each
reported
concentration
is
followed
by
the
designation
for
the
monitoring
well
that
was
sampled.
All
wells
are
within
2
miles
of
Sources
1
and
2
at
the
Del
Am0
site.
All
wells
were
not
sampled
during
each
sampling
event.

­
Chlorobenzene
concentrations
in
micrograms
per
liter
@g/
l)

UpperBellflowerBellflowerSandGageAquiferLynwood
Date
4/
90
38,00O(
MW01)
6(
MW03)
500(
MW04)
34,00O(
MW05)
7,00O(
MW06)
lSO,
OOO(
MWO9)
82O(
MWlO)
20,000(
Mw11)
8,20O(
MW
12)
2,6OO(
MW
13)
400(
MW
14)
22,00O(
MW15)
2(
MW17)
990(
MW25)
6(
MW26)

8/
90
2(
MW17)
l(
MW24)
990(
MW25)
5(
MW26)
480(
BF01)
4,70O(
BF02)
9,00O(
BF03)
3
1,00O(
BF04)
2,30O(
BF05)
27,00O(
BF06)
45,00O(
BF07)
6,60O(
BF08)
12,00O(
BF09)
2,10O(
BFll)
17800(
BF14)
42,0OO(
BF15)
150(
BF16)
4,10O(
BF17)

23,00O(
BFll)
2,00O(
BF14)
36,00O(
BF15)
160(
BF16)
4,30O(
BF17)
230(
GO1)
9,60O(
G02)
2,20O(
G03)
2,00O(
G04)
14,00O(
G05)
2,40O(
G06)
90(
G07)
120(
608)
970(
G12)
1,40O(
G13)
390(
LG2)

99(
G08)
4(
G11)
l,
000(
G
12)
1,60O(
G13)
70(
LG1)
12(
LWOl)
16,
Fig.
2­
5,
Tbl~.
F­
1
thm
F­
4;
24,
Tbl.
D­
1,
APP.
E
52(
LW01)
16,
Fig.
2­
5,
Tbls.
F­
1
thm
F­
4;
25,
Tbl.
A­
1,
App.
B
52
GW­
General
UpperBellflowerBellflowerSandGageAquiferLynwood
Date
11/
90
28,0OO(
MW05)

12/
90
5,80O(
MW12)
5,20O(
MW12)
to
419
146,00O(
MW05)
7,80O(
MW06)
5,70O(
MW12)

7/
92
1/
93
73,00O(
MW01)
29,00O(
BF04)
4,70O(
BF08)
200(
BF16)
3,30O(
BF17)
3,60O(
BF17)

23,00O(
BF04)
3,40O(
BF05)
3,50O(
BF08)
180(
BF16)
3,60O(
BF17)

20,00O(
BF09)
20(
BF26)
18(
BF26.)
370(
BF3
1)

18,00O(
BF09)
15(
BF26)
18(
BF26)
410(
BF31)
310(
G01)
1,30O(
G04)
72(
G07)
SS(
G08)
1,40O(
G13)

170(
G01)
7,00O(
G02)
1,50O(
G04)
63(
G07)
73(
G08)
1,50O(
G13)

490(
G03)
180(
G19)
220(
G19)

1,1OO(
G03)
370(
G19)
68(
LW01)
16,
Fig.
2­
5,
70(
LW01)
Tbl~.
F­
1thm
F­
4;
26,
Tbls.
B­
1
and
B­
7,
App.
C
and
APP.
D
93(
LW01)
16,
Fig.
2­
5
Tbls.
F­
1
thru
F­
4;
27,
Tb:
B­
1,
App.
C
470(
LW01)
16,
Fig.
2­
5;
520(
LW01)
28,
Tbls.
B­
1
and
B­
5,
App.
C
and
App.
D
510(
LW01)
16,
Fig.
2­
5;
29,
Tbls.
B­
1
and
B­
5,
App.
C
and
App.
D
­
p­
CBSA
concentrations
in
,ugA
DateUpperBellflower
'
BellflowerSandGageAquiferLynwoodRefs.
Aquifer
11/
9024,00O(
MW05)
72,00O(
BF04)
500(
GOl)
­­­
16,
Fig.
2­
5,

12/
90
54,
OOO(
MW12)
5,50O(
BF16)
9,30O(
G04)
Tbl.
B­
2,
to
Tbl.
F­
6;
26,

5,5OO(
MW14)
l,
OOO(
G08)
22,00O(
G13)

419
1
1,90O(
MW23)
7,30O(
BF05)
2,70O(
G09)
270(
LW01)
16,
Fig.
2­
5,
8,90O(
BF07)
1,40O(
LW02)
Tbl.
F­
6;
27,
3,20O(
BF10)
Tbl.
B­
2,
1,10O(
BF12)

53
GW­
General
UpperBellflowerBellflowerSandGageAquiferLynwood
Date
10/
9
1
­"
3,50O(
BF20)
170(
G15)
"_
16,
Fig.
2­
5,
33,00O(
BF21)
,
3,00O(
G17)
Tbl.
F­
6;
30,
3,40O(
BF22)
210(
G19)
Tbl.
I­
1,
App.
630(
BF23)
J
49,00O(
BF24)
8,00O(
BF25)
7,70O(
BF26)
770(
BF27)
180(
BF28)
790(
BF29)
7,20O(
BF31)
7,10O(
BF32)
1,20O(
BF33)

Stratigraphic
Information
Stratigraphic
information
indicates
that
the
unnamed
aquitard
between
the
Lynwood
and
Silverado
aquifers
is
not
laterally
continuous
within
2
miles
of
the
Del
Am0
site.
The
site
is
approximately
1
mile
east
of
the
coastal
area
where
merging
of
the
Lynwood
and
Silverado
aquifers
is
known
to
occur
(ref.
1,
p.
51553;
ref.
15,
p.
75,
Plates
6C
and
20).

54
3.1
Likelihood
of
Release
GW­
ObservedRelease
I
r­
I
3.1.1ObservedRelease
Aquifer
Being
Evaluated:
upper
BellflowerLBellflower
sand/
Gage/
Lynwood/
Silverado
Direct
Observation:

An
observed
release
to
ground
water
by
direct
observation
has
been
established.
Contaminated
soil
associated
with
Pits
2A
through
2F
has
come
to
be
located
below
the
top
of
the
upper
BellflowerLBellflower
sand/
Gage/
Lynwood/
Silverado
aquifer,
due
to
a
rising
water
table
(ref.
5,
pp.
4­
16,5­
35,
and
5­
40).
In
1987,
hazardous
substances
were
found
in
soil
samples
from
borings
to
depths
of
18
to
20
feet
below
mean
sea
level
(bmsl)
(depending
on
the
boring
location).
Between
1987
and
1995,
the
water­
table
rose
from
26
to
27
feet
bmsl
in
1987,
to
15
to
19
feet
bmsl
in
1995
(ref.
62).

Basis
for
Direct
Observation:
Soil
sampling
results
indicate
that,
by
1987,
hazardous
substances
present
in
Source
1
(e.
g.,
benzene,
ethylbenzene,
and
naphthalene)
had
migrated
to
a
depth
of
at
least
57
feet
.bgs
(boring
locations
B­
3B­
2,
B­
3B­
3,
and
€3­
5B­
1)
below
the
pits
in,
what
was
at
that
time,
the
unsaturated
zone
(Reference
31,
Table
3).
The
depth
measurement
of
57
feet
is
reported
in
units
of
"feet
bgs"
because
elevation
data
were
not
provided
in
the
boring
logs
for
the
1987
soil
sampling
event
(ref.
3
1,
Appendix
A­
1).
At
boring
location
B­
3B­
2,
the
depth
measurement
of
57
feet
can
be
converted
to
units
of
bmsl
by
using
elevation
data
from
a
nearby
boring
(SBL0002)
that
was
drilled
in
1992
as
part
of
a
waste
excavation
feasibility
study.
The
reported
ground
surface
elevation
for
boring
SBL0002
is
37.21
feet
above
mean
sea
level
(amsl)
(ref.
5,
Figure
5.5­
1;
ref.
12,
Appendix
A,
Attachment
A3,
p.
A3­
7).
Subtracting
37.21
feet
amsl
from
57
feet
bgs
yields
a
contaminated
soil
depth
of
19.79
feet
bmsl.
At
boring
location
B­
3B­
3,
the
depth
measurement
of
57
feet
can
be
converted
to
units
of
feet
bmsl
by
using
elevation
data
from
a
nearby
boring
(PZL0019)
that
was
drilled
in
1993
as
part
of
the
Phase
I
RI
for
the
Del
Am0
site.
The
reported
ground
surface
elevation
for
boring
PZLOO19
is
38.54
feet
amsi
(ref.
5,
Figure
5.5­
1,
Appendix
B,
p.
B­
7).
Subtracting
38.54
feet
amsl
from
57
feet
bgs
yields
a
contaminated
soil
depth
of
18.46
feet
bmsl.
At
boring
location
B­
5B­
1,
the
depth
measurement
of
57
feet
bgs
can
be
converted
to
units
of
feet
bmsl
by
using
elevation
data
from
an
adjacent
boring
(VWL0006)
that
was
drilled
in
1992
to
facilitate
the
installation
of
a
treatability
study
well.
The
reported
ground
surface
elevation
for
boriqg
VWL0006
is
36.96
feet
amsl
(ref.
5,
Figure
5.5­
1;
ref.
21,
pp.
3­
1
and
3­
4,
Figure
2­
2,
Appendix
C,
p.
5).
Subtracting
36.96
feet
amsl
from
57
feet
bgs
yields
a
contaminated
soil
depth
of
20.04
feet
bmsl.
5
Water
level
measurements
indicate
that
the
water
table
in
the
West
Coast
Basin
has
risen
at
a
rate
of
approximately
1
foot
per
year
since
the
mid
to
late
1970s.
This
coincides
with
the
timing
of
the
adjudication
of
the
basin,
which
effectively
reduced
ground
water
pumping
to
a
prescribed
annual
withdrawal
(ref.
5,
p.
4­
16).
Ground
water
elevation
data
are
provided
on
the
following
table
to
document
the
rising
water
table
in
the
vicinity
of
Source
1
between
1987
and
1995.

55
:~
L"­.
l~­.
uj_
~­~~­~..~­~.~,..~.~~,~~"~
=..,.>
:~~­~E
Y
~­~~~­~~~~~~~­L
I
.
am,.
."
L
"."
A
"A
t
>x­~­*"
""""

\

GW­
Observed
Release
Water
Table
Elevations
from
1987
to
1995
in
the
Vicinity
of
Source
1
3.1
Likelihood
of
Release
Sample
9/
93
2/
94
6/
95
&
7/
95
Location
DM­
1
*

DM­
2"

DM­
3
*

P­
2"

P­
3"

>
PzLOO18""

PZLOO19""

PzL0020**

PZLOO22*"

PZLOO23""

PZLOO24""

PZLOO25""
5,
Fig.
4.2.1;
11,
App.
E;
31,
Tbl.
13,
Fig.
7
5
,
Fig.
4.2.1;
11,
App.
E;
31,
Tbl.
13,
Fig.
7
11,
App.
E;
31,
Tbl.
13,
Fig.
7
5,
Fig.
4.2.1;
22,
Fig.
5;
31,
Tbl.
13,
Figs.
7
&
9,
46,
Fig.
3
31,
Tbl.
13,
Figs.
7
&
10;
46,
Fig.
3
5,
Tbl.
2.9­
2,
Fig.
4.2.1,
App.
B;
22,
Fig.
5;
46,
Fig.
2
5
,
Tbl.
2.9­
2,
Fig.
4.2.1,
App.
B;
22,
Fig.
5;
46,
Fig.
2
5,
Tbl.
2.9­
2,
Fig.
4.2.1,
App.
B;
22,
Fig.
5;
46,
Fig.
2
5,
Tbl.
2.9­
2,
Fig.
4.2.1,
App.
B;
46,
Fig.
2,
App.
A
5,
Tbl.
2.9­
2,
Fig.
4.2.1,
App.
B;
22,
Fig.
5
5,
Tbl.
2.9­
2,
Fig.
4.2.1,
App.
Bi
22,
Fig.
5;
46,
Fig.
2
5,
Tbl.
2.9­
2,
Fig.
4.2.1,
App.
B;
22,
Fig.
5;
46,
Fig.
2
25.90
25.67
26.28
25.93
27.23
"­

"e
"*

­e­

"­

"e
"e
20.15
20.25
20.27
"­
..

20.15
19.54
17.42
19.52
19.32
18.92
19.1
1
"e
"­

"e
20.19.

"e
20.08
19.32
17.70
18.88
19.71
18.68
19.37
17.96
19.29
17.31
16.88
15.16
18.83
"­

16.26
16.86
56
GW­
Observed
Release
Notes:
*
Monitoring
well
completed
in
the
water
table
zone
**
Piezometer
completed
in
the
water
table
zone
­­­
Not
sampled
­
Hazardous
Substances
in
theRelease
In
1987,
Woodward­
Clyde,
for
the
State
of
California
Department
of
Health
Services,
drilled
11
soil
borings
in
the
vicinity
of
Source
1
(ref.
31,
Figure
2).
Three
of
the
borings
were
within
25
feet
of
the
pits
(B­
3B­
2,
located
15
feet
north
of
Pit
2D;
B­
3B­
3,
located
22.5
feet
north
of
Pit
2D;
and
B­
5B­
1,
located
15
feet
north
of
Pit
2C)
(ref.
3
1,
Table
3).
These
three
borings
are
probably
located
even
less
than
25
feet
from
the
pits
because
the
protrusion
at
the
northern
end
of
each
pit,
which
measures
12.
to
15
feet
in
length,
was
not
accounted
for
during
the
1987
investigation
(ref.
7,
p.
2­
2,
Table
3­
5;
ref.
31,
p.
8).
An
additional
soil
boring
(B­
2B­
2)
was
drilled
50
feet
south
of
Pit
2B
and
was
considered
to
be
a
background
location
due
to
its
distance
from
the
pits
(ref.
31,
Figure
2).
Soil
samples
were
collected
from
the
four
borings
at
depths
up
to
57
feet
bgs
and
were
analyzed
for
polynuclear
aromatics
using
EPA
Method
8310
and
volatile
aromatic
hydrocarbons
using
EPA
Method
8240
(ref.
31,
Table
3).
Analytical
results
indicated
the
presence
of
benzene
in
a
sample
collected
from
boring
B­
3B­
2
at
a
concentration
of
1,300
mgkg
at
57
feet
bgs;
in
samples
collected
from
boring
B­
3B­
3
at
concentrations
of
3,000
mgkg
at
17
feet
bgs,
1,200
mgkg
at
33
feet
bgs,
and
2,500
mgkg
at
57
feet
bgs;
and
in
samples
collected
from
boring
B­
5B­
1
at
concentrations
of
1,500
mgkg
at
17
feet
bgs
and
1,700
mgkg
at
57
feet
bgs.
In
the
background
boring
(B­
2B­
2),
benzene
was
detected
at
a
concentration
of
0.5
mgkg
at
25
feet
bgs
and
was
not
detected
at
57
feet
bgs.
In
addition,
the
results
indicated
the
presence
of
other
analytes
(e.
g.,
ethylbenzene
and
naphthalene)
at
concentrations
above
background
levels
at
depths
up
to
57
feet
bgs
(ref.
31,
Table
3).

A
1995
ground
water
monitoring
report
for
the
Del
Am0
Study
area
shows
that
there
is
contamination
under
the
waste
pits
down
to
ground
water.
Concentrations
in
the
water
table
under
the
pits
are
as
high
as
half­
a­
million
ppb
(ref.
47;
ref.
48,
pp­
7,
32,
256).

An
additional
observed
release
to
ground
water
by
direct
observation
has
been
established.
Spillage
from
a
historic
crude
benzene
storage
tank
has
come
to
be
located,
as
a
NAPL,
in
the
upper
saturated
zone
of
the
upper
BellflowerEiellflower
sand/
Gage/
Lynwood/
Silverado
aquifer,
due
to
a
rising
water
table
(ref.
50,
p.
4­
1)
(see
Sections
2.2
and
2.4.2
for
Source
3).

Chemical
Analysis:

An
observed
release
by
chemical
analysis
can
be
documented
using
1995
ground
water
sampling
data
that
indicate
that
benzene
concentrations
have
increased
significantly
above
background
levels
proximal
to
Source
3.

Nine
specific
ground
water
monitoring
events
were
conducted
for
the
Del
Am0
site
during
the
period
from
February
1993
through
February
1996.
Analytical
data
from
the
third
sampling
period
in
1995
(October
through
December
1995)
were
selected
for
presentation
in
the
May
15,
1998
Del
Am0
Final
Ground
Water
FU
report
because
"this
event
is
relatively
recent
and
comprehensive
with
respect
to
the
number
of
locations
and
analytes
for
which
there
are
data"
(ref.
50,
pp.
5­
4,5­
5).
The
analytical
data
from
this
event
that
are
"

57
GW­
Observed
Release
relevant
to
benzene
in
what
the
1998
Del
Am0
Final
Ground
Water
RI
report
refers
to
as
the
water
table
zone
in
the
vicinity
of
Source
3
are
presented
in
the
table
below.
The
water
table
zone
corresponds
to
the
Upper
'

Bellflower
aquifer
discussed
in
Section
3.0.1
(Ground
Water
Pathway
­
General
Considerations)
(ref.
50,
p.
4­
2).

Water
level
measurements
taken
in
October
1995
indicate
that
the
ground
water
flow
direction
in
the
water
table
zone
in
the
vicinity
of
Source
3
is
to
the
south­
southwest
(ref.
50,
p.
4­
2,
Figure
4.1­
3).
Monitoring
wells
PZL0009
and
EL0016
are
designated
as
background
wells
in
the
table
below
because
they
are
located
hydraulically
upgradient
of
Source
3
(i.
e.,
approximately
900
feet
northeast
and
500
feet
north
of
Source
3,
respectively).
Monitoring
wells
SWL0002,
SWL0003,
and
SWL0004
are
designated
as
contaminated
wells
because
they
are
proximal
to
the
NAPL
area
(ref.
53).

Screened
Detection
Monitoring
Interval
Sample
Sampling
Benzene
Limit
Well
ID
(feet
bgs)
ID
Date
.
(PLg/
L)
bg/
L)
Reference
PZLOoo9
PZLOO
16
SWLOOO2
SwL0003
SWLOOO4
Attribution
54­
69
47­
67
52­
77
50­
77
53­
80
,
BackgroundWells
GWSO135010/
17/
95
940
GWSO1268lot24195Not
detected
Contaminated
Wells
GWSO131610/
20/
95
310,000
GWSO1317
10/
20/
95
330,000
GWSO1318
10/
20/
95
1,200,000
5
30
..

20,000
2,000
5,000
50,
Fig.
5.2­
2,
App.

G3,
Record
93426
50,
Fig.
5.2­
2
App.
G3,
Record
86540
C,
Tbl.
C­
2,
App.

App.
C,
Tbl.
C­
2,

50,
Fig.
5.2­
2
App.
G3,
Record
91
159
50,
Fig.
5.2­
2
App.
G3,
Record
91311
50,
Fig.
5.2­
2
App.
G3,
Record
91391
App.
C,
Tbl.
C­
2,

App.
C,
Tbl.
C­
2,

App.
C,
Tbl.
C­
2,

As
presented
in
the
above
table,
ground
water
sampling
results
indicate
that
benzene
meets
observed
release
58
GW­
Observed
Release
criteria
(i.
e.,
concentrations
have
increased
significantly
above
background
levels).
The
Source
3
NAPL,
which
is
composed
of
90
percent
benzene,
is
located
between
the
background
monitoring
wells
(PZL0009
and
PZL0016)
and
the
contaminated
wells
(SWL0002,
SWL0003,
and
SWL0004)
that
document
this
release
(ref.
50,
Figure
5.2­
2;
ref.
51,
p.
12;
ref.
53).
The
NAPL
is
located
approximately
50
feet
from
the
historic
location
of
a
500,000­
gallon
tank
that
was
used
for
storage
of
crude
benzene
during
the
years
that
the
styrene
manufacturing
plant
was
operating
(Le.,
1942
to
1969)
(ref.
5,
p.
5­
22;
ref.
51,
Figure
16;
ref.
52,
p.
7­
4).
Aerial
photographs
and
site
history
documents
indicate
that
spillage
occurred
during
transfer
of
tank
contents
to
and
from
railroad
cars
and
trucks
(ref.
5,
p.
3­
12,
Appendix
A,
pp.
A­
6,
A­
7,
A­
29,
Plate
A­
1).
Results
of
a
1992
shallow
soil
gas
sampling
event
indicated
the
presence
of
benzene
at
a
concentration
of
128
parts
per
million
by
volume
(ppmv)
at
a
depth
of
6
feet
bgs
at
one
sampling
location
(SGLOOO5)
iri
the
vadose
zone
beneath
the
historic
location
of
the
crude
benzene
storage
tank
(ref.
51,
pp.
3,9,
10,
Figure
8).
During
a
subsequent
soil
sampling
event,
benzene
was
either
not
detected
or
detected
at
trace
concentrations
in
the
vadose
zone
(ref.
5,
pp.
2­
18,5­
19
through
5­
22,
Figure
5.4­
3).
The
absence
of
significant
benzene
contaminated
soil
is
inferred
to
be
due
to
natural
degradation
processes
that
have
occurred
in
an
aerobic
vadose
zone
soil
environment
since
the
benzene
was
released
(ref.
5,
p.
5­
22;
ref.
50,
p.
1­
14).
Based
on
the
time
period
during
which
the
styrene
manufacturing
plant
operated
(i.
e.,
1942
to
1969),
the
release
occurred
between
31
and
58
years
ago
(ref.
5,
p.
5­
22).

There
do
not
appear
to
be
any
known
alternate
contributors.
As
part
of
the
Del
Am0
Ground
Water
RI,
regional
ground
water
contamination
source
areas
outside
of,
but
in
the
vicitiity
of
the
historic
Del
Am0
synthetic
rubber
manufacturing
plant
property,
were
identified.
Identification
was
based
on
the
following
publicly
available
information
from
regulatory
agency
files:
ground
water
analytical
data
indicating
elevated
concentrations
of
one
or
more
VOCs
at
water
table
monitoring
locations
relative
to
surrounding
areas,
a
history
of
land
use
consistent
with
the
reported
VOC
ground
water
contamination,
and/
or
data
indicating
elevated
VOC
concentrations
in
soil
(ref.
50,
p.
5­
19).
Water
level
measurements
taken
in
October
1995
indicate
that
ground
water
flow
in
the
water
table
zone
(i.
e.,
Upper
Bellflower
aquifer),
in
the
vicinity
of
Source
3,
is
to
the
soutWsouthwest
(ref.
50,
p.
4­
2,
Figure
4.1­
3).
Results
of
the
Del
Am0
Ground
Water
RI
regional
ground
water
contamination
study
indicate
that
there
are
no
facilities
to
the
northeast
of
the
historic
Del
Am0
plant
property
that
were
or
are
alternate
contributors
to
the
benzene
contamination
documented
in
Del
Amo
monitoring
wells
SWL0002,
SWL0003,
and
SWL0004
(ref.
50,
Figures
4.1­
3,5.3­
1).
Two
source
areas
of
VOC
contamination
(i.
e.,
the
Amoco
and
Trico
facilities)
were
identified
adjacent
to
the
western
border
of
the
historic
Del
Amo
plant
in
the
vicinity
of
these
three
monitoring
wells;
however,
the
VOCs
associated
with
these
facilities
do
not
include
benzene
(ref.
50,
Figure
5.3­
l)."

Ground
Water
Observed
Release
Factor
Value:
550
59
GW­
Waste
Characteristics
3.2.1
Toxicity/
Mobility
3.2
WasteCharacteristics
Hazardous
Substance
Source
No.
Toxicity
Mobility
Toxicity/
Mobility
Reference
Benzene
192,
3
100
1
100
2,
p.
B­
2
Ethylbenzene
1,253
'
10
0.01
0.1
2,
p.
B­
10
'.

Naphthalene
192
100
1
100
2,
p.
B­
14
See
Section
2.4.1
(Hazardous
Substances)
for
Sources
1,2,
and
3
for
evidence
of
the
presence
of
benzene,
ethylbenzene,
and
naphthalene
in
the
sources.

The
toxicity/
mobility
factor
value
assigned
for
the
ground
water
pathway
is
100,
based
on
benzene
and
naphthalene
(ref.
1,
Section
3.2.1.3).

3.2.2
Hazardous
Waste
Quantity
Source
Hazardous
Is
source
hazardous
Waste
Quantity
constituent
quantity
Source
Number
Value
(Section
2.4.2.1.5)
data
complete?
(yesino)
1
728
No
2
3,357
No
3
6,160
No
Sum
of
Values:
10,245
The
hazardous
waste
quantity
factor
value
assigned
for
the
ground
water
pathway
is
10,000
(ref.
1,
Table
2­
6,
Section
2.4.2.2).

3.2.3
Waste
Characteristics
Factor
Category
Value
Multiplying
the
toxicity/
mobility
factor
value
of
100
x
the
hazardous
waste
quantity
factor
value
of
10,000
produces
1,000,000,
which
yields
a
waste
characteristics
factor
category
value
of
32
for
the
ground
water
pathway
(ref.
1,
Table
2­
7).

Waste
Characteristics
Factor
Category
Value:
32
..

60
GW
­
Targets
3.3
Targets
Distance
Level
I
Level
II
Potential
From
Contamination
Contamination
Contamination
­
Well
Source
Aquifer
(Y/
N)
(Y/
N)
(Y
N
Reference
DWC
*
N
N
Y
32,38
scwc
1.6
*
N
N
Y
32,
40..
Dalton
DWC
19A
1.8
*
N
N
Y
32,38
DWC
79
2.6
*
N
N
y
32,38
TWD
2.6
*
N
N
Y
32,39
"

DWC
*
N
N
Y
32,38
scwc
3.5
*
N
N
Y
32,40
Cerise
DWC
77
3.6
*
N
N
Y
32,38
DWC
15
3.9
*
N
N
Y
32,38
DWC
16
3.9
*
N
N
Y
32,38
DWC
98
3.9
*
N
N
Y
32,38
scwc
3.9
*
N
N
Y
32,40
Southern
3
scwc
3.9
*
N
N
Y
32,40
Southern
4
scwc
3.9
*
N
N
Y
32,40
Southern
5
Notes:
*
=
interconnected
upper
BellflowerA3ellflower
SandGageLynwoodSilverado
DWC
=
Dominguez
Water
Company
SCWC
=
Southern
California
Water
Company
TWD
=
City
of
Torrance
Water
Department
.L
­­­
61
GW­
Nearest
Well
3.3.1
Nearest
Well
Well:
DWC
97
Level
of
Contamination
(I,
11,
or
potential):
potential
If
potential
contamination,
distance
from
source
in
miles:
1.5
miles
from
Source
3
(ref.
32;
ref.
38,
p.
2).

Nearest
Well
Factor
Value:
5
62
GW
­
Potential
Contamination
3.3.2Population
3.3.2.4
Potential
Contamination
Distance
Category(
miles)
PopulationReferencesDistance­
WeightedPopulationValue
0
to
0.25
0
>
0:
25
to
0.5
0
>
0.5
to.
1
0
>1to2
7,682
20,32,33,35,36,37,38,40
>2to3
12,179
20,
32,34,35,38,49
>3to4
24,529
20,32,33,
35,36,
37,38,40
939
2,122
1,306
Sum
ofDistance­
WeightedPopulationValues:
4,367
The
following
three
water
purveyors
operate
14
drinking
water
wells
within
4
miles
of
Sources
1,
2,
and
3:
Dominguez
Water
Company,
Southern
California
Water
Company,
and
the
City
of
Torrance
Water
Department.
The
information
that
was
used
to
calculate
the
population
served
by
each
well
is
presented
below.
'
Since
the
relative
contributions
of
surface
water
and
ground
water
to
each
system
vary
from
year
to
year,
this
component
of
the
calculations
was
based
on
a
10­
year
average
(i.
e.,
1990
through
1999).
The
total
population
served
by
each
system,
the
number
of
active
and
standby
wells
in
each
system,
and
individual
well
pumpage
data
were
based
on
the
most
current
year
for
which
information
is
available
(i.
e.,
1999).

Dominguez
Water
Company
The
Dominguez
Water
Company
operates
a
blended
drinking
water
system
that
serves
approximately
100,000
people
in
the
city
of
Carson.
In
1999,
there
were
13
active
wells,
no
standby
wells,
and
one
surface
water
intake
[i.
e.,
imported
surface
water
purchased
from
the
Metropolitan
Water
District
(MWD)]
contributing
to
the
system
(ref.
38,
pp.
1,
2).
The
relative
contributions
of
surface
water
and
ground
water
for
1.990
through
1999
are
as
follows:
..

Contribution
from
IntakeContributionfromWells
Calendar
1990
p.
2;
38,
p.
1
1991
1992
27
20
20,
p.
2;
38,
p.
1
20,
p.
2;
38,
p.
1
1993
0
38,
p.
2
1994
13
35;
38,
p.
2
\

1995
64
36
38,
p.
2
."

63
GW
­
Potential
Contamination
Contribution
from
IntakeContributionfromWells
Calendar
Year
(percent)
(percent)
Reference
1996
35
65
38,
p.
2
1997
30
70
38,
p.
2
1998
32
68
38,
p.
2
1999
31
69
38,
p.
2
Average:
61
(612
t
10)
39
(388
+
10)

Since
the
relative
contribution
of
one
well
or
intake
exceeds
40
percent
(i.
e.,
10­
year
average
yields
a
61
percent
relative
contribution
for
the
surface
water
intake),
the
population
served
by
each
well
was
apportioned
based
on
pumpage.
As
presented
below,
the
pumpage
for
each
well
within
4
miles
of
Sources
1,
2,
and
3
was
divided
by
the
sum
of
the
pumpages
for
all
13
wells
in
the
system
(12,270
gpm).
This
quotient
was
then
multiplied
by
the
population
served
by
ground
water
(0.39
X
100,000
=
39,000)
(ref.
32;
ref.
38,
pp.
172).

Pumpage
Well
(am)
Calculations
Served
(miles)
DWC
97
7
10
(710
t
12,270)
X
39,000
=
2,257
>1t02
DWC
19A
1,111
(1,111
t
12,270)
'~
39,000
=
3,531
>1t02
DWC
79
843
(843
+
12,270)
x
39,000
=
2,679
>2t03
DWC
75A
1,160(
1,160
+
12,270)
x
39,000
=
3,687
>3t04
DWC
77
703(
703
t
12,270)
x
39,000
=
2,234
>3t04
DWC
15
717(
717
+
12,270)
x
39,000
=
2,279
>3t04
DWC
16
442(
442
t
12,270)
X
39,000
=
1,405
>3t04
DWC
98
2,609(
2,609
+
12,270)
X
39,000
=
8,293
>3t04
DWC
72A
543
NIA
NIA
>4
DWC
23B
748
NIA
NIA
>4
DWC
31A
582
NIA
DWC
90
861
NIA
DWC
94
1,241
NIA
Total
Pumpage:
12,270
NIA
>4
NIA
>4
NIA
>­
4
1
64
GW
­
Potential
Contamination
Southern
Cal$
ornia
Water
Company
The
Southern
California
Water
Company's
Southwest
System
is
a
blended
drinking
water
system
that
had
49,344
active
service
connections
in
1999
(ref.
40,
p.
1).
The
average
number
of
persons
per
residence
for
Los
Angeles
County
is
2.91
(ref.
37,
p.
4).
The
system,
therefore,
serves
approximately
143,591
people
(2.91
x
49,344).
In
1999,
there
were
14
active
wells,
two
staridby
wells,
and
one
surface
water
intake
(i.
e.,
imported
surface
water
purchased
from
the
MWD)
contributing
to
the
system
(ref.
40,
p.
1).
The
relatiye
contributions
of
surface
water
and
ground
water
for
1990
through
1999
are
as
follows:

ContributionfromIntakeContributionfromWells
Calendar
Year
(percent)
(percent)
Reference
.

1990
81
19
33,
p.
1
1991
76
24
33,
p.
1
1992
1993
1994
1995
1996
1997
1998
23
23
22
19
15
16
25
33,
p.
1
33,
p*
1
36
40,
p.
1
40,
p.
1
40,
p.
1
40,
p.
1
1999
74
26
40,
p.
1
Average:
79
(788
.+
10)
21
(212
f
10)

Since
the
relative
contribution
of
one
well
or
intake
exceeds
40
percent
(i.
e.,
10­
year
average
yields
a
79
percent
relative
contribution
for
the
surface
water
intake),
the
population
served
by
each
well
was
apportioned
based
on
pumpage.
As
presented
below,
the
pumpage
for
each
well
within
4
miles
of
Sources
1,
2,
and
3
was
divided
by
the
sum
of
the
pumpages
for
all
16
wells
in
the
system
(9,550
gpm).
This
quotient
was
then
multiplied
by
the
population
served
by
ground
water.(
0.21
x
143,591
=
30,154)
(ref.
33;
p.
1,
ref.
36;
ref.
40,
pp.
1,2).

65
GW
­
Potential
Contamination
Pumpage
Well
(a
m
)
Calculations
Served
(miles)

SCWCDalton
600
SCWCCerise
400
SCWCSouthern
.3
300
SCWCSouthern
4
400
SCWCSouthern
5
1,000
scwc
Chicago
1
scwc
Compton­
Doty
scwc
Yukon
1
scwc
Yukon
2
scwc
Ballona
3
scwc
Bellhaven
1
scwc
Bellhaven
3
scwc
Doty
1
scwc
Doty
2
scwc
Goldmedal
1
scwc
129'h
Street
Total
Pumpage:
500
500
200
200
200
600
950
1,000
1,000
1,500
200
9,550
(600
+
9,550)
X
30,154
=

(400
+
9,550)
x
30,154
=

(300
+
9,550)
x
30,154
=

(400
+
9,550)
X
30,154
=

(1,000
+
9,550)
X
30,154
=

NIA
NIA
NIA
NIA
NIA
NIA
NIA
NIA
NIA
NIA
NIA
1,894
1,263
947
1,263
3,158
NIA
NIA
NIA
NIA
NIA
NIA
NIA
NIA
NIA
NIA
NIA
>
1
to2
>3t04
>3t04
>3t04
>3t04
>4
>4
>4
>4
>4
>4
>4
>4
>4
>4
>4
66
GW
­
Potential
Contamination
City
of
Torrance
Water
Department
The
City
of
Torrance
Water
Department
operates
a
blended
drinking
water
system
that
served
approximately
95,000
people
in
1999.
In
1999,
there
was
one
active
well
and
one
surface
water
intake
(i.
e.,
imported
surface
water
purchased
from
the
MWD)
contributing
to
the
system
(ref.
39).
The
relative
contributions
of
surface
water
and
ground
water
for
1990
through
1999
are
as
follows:

Contribution
from
IntakeContributionfromWells
Fiscal
1989/
1990
199011991
199111992
79
199211
92
199311994
12
21
8
2
199411995
199511,996
199611997
92
6
8
199711998
49
49
49
49
34;
49
49
49
49
199811999
86
Average:
90
(898
+
10)
14
49
10
(102
t
10)

As
presented
below,
the
population
served
by
the
one
well
that
was
active
in
1999
was
calculated
by
multiplying
the
10­
year
average
relative
contribution
for
ground
water
by
the
total
population
served
by
the
system
in
1999
(0.10
x
95,000
=
9,500)
(ref.
39;
ref.
49).

Pumpage
Well
(gPm)
Calculations
Served
(miles)
TWD
6
NIA
0
9,500
>2t03
Potential
Contamination
Factor
Value:
436.7
67
GW­
Resources
3.3.3
Resources
There
are
no
ground
water
wells
located
within
4
miles
of
the
Del
Am0
site
that
are
known
to
be
used
for
the
following
purposes:
irrigation
of
commercial
food
.or
forage
crops,
watering
of
commercial
livestock,
ingredient
in
commercial
food
preparation,
supply
for
commercial
aquaculture,
or
supply
for
a
designated
water
recreation
area.

Resources
Factor
Value:
0
68
GW­
Wellhead
Protection
Area
3.3.4
Wellhead
Protection
Area
There
are
no
designated
wellhead
protection
areas
within
4
miles
of
the
Del
Am0
site.

\

Wellhead
Protection
Area
Factor
Value:
0
69
SW­
General
Considerations
4.0
SURFACE
WATER
MIGRATION
PATHWAY
The
surface
water
pathway
was
evaluated,
but
not
scored,
because
there
are
a
iimited
number
of
targets
associated
with
the
first
7.5
miles
of
the
15­
mile
in­
water
segment
(ref.
41;
ref.
42).
Runoff
from
the
Del
Amo
site
enters
a
storm
drain
inlet
located
at
the
intersection
of
Vermont
Avenue
and
Del
Am0
Boulevard,
approximately
600
feet
southeast
of
Sources
1
and
2
(ref.
5,
Plate
3­
3;
ref.
43,
p.
36;
ref.
44).
The
storm
drain
system
discharges
into
the
Torrance
Lateral,
which
is
an
open
channel,
approximately
1,600
feet
south
of
the
storm
drain
inlet.
'
The
Torrance
Lateral
discharges
into
the
Dominguez
Channel,
which
is
a
concrete­
lined
drainage
and
flood
control
channel,
approximately
1.5
miles
downstream
of
the
storm
drain
system
discharge
point
(ref.
44;
ref.
45,
p.
7).
The
Dominguez
Channel
discharges
into
the
Los
Angeles
Harbor
approximately
6
miles
further
downstream.
The
Los
Angeles
Harbor
empties
into
San
Pedro
Bay,
and
San
Pedro..
Bay
opens
onto
the
Pacific
Ocean.
The
last
portion
of
the
15­
mile
in­
water
segment
consists
of
an­
arc
with
a
7.5­
mile
radius
that
extends
from
the
confluence
of
the
Dominguez
Channel
and
the
Los
Angeles
Harbor
into
San
Pedro
Bay
and
the
Pacific
Ocean
(ref.
44).
Although
there
are
fisheries
and
sensitive
environments
associated
with
the
Los
Angeles
Harbor,
San
Pedro
Bay,
and
the
Pacific
Ocean;
there
do
not
appear
to
be
any
drinking
water
intakes
or
sensitive
environments
associated
with
the
first
7.5
miles
of
the
15­
mile
in­
water
segment
(i.
e.,
the
Torrance
Lateral
and
concrete­
lined
Dominguez
Channel).
In
addition,
there
are
a
limited
number
of
fish
in
the
Dominguez
Channel
(ref.
41;
ref.
42).

70
SE­
General
Considerations
5.0
SOIL
EXPOSURE
PATHWAY
The
soil
exposure
pathway
was
evaluated,
but
not
scored,
because
the
area
of
the
Del
Amo
site
that
is
occupied
by
Sources
1
and
2
is
currently
vacant
and
covered
with
fill
material
and
vegetation.
In
addition,
Sources
1
and
2
are
separated
from
De
Am0
Boulevard
and
a
residential
area
to
the
south
by
a
double
row
of
fences
(ref.
5,
p.
5­
23).
Source
3
is
currently
present
as
an
area
of
non­
aqueous
phase
liquid
(NAPL)
located
60
feet
below
ground
surface
(ref.
50,
pp.
4­
1,6­
20).

c
71
Air­
General
Considerations
6.0
AIR
MIGRATION
PATHWAY
The
air
pathway
was
evaluated,
but
not
scored,
because
no
known
ambient
air
sampling
and
meteorological
monitoring
have
been
conducted
on
or
in
the
vicinity
of
the
Del
Am0
site.

72
