Document ID: EPA-HQ-OW-2004-0002-0043
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2004-11-23T05:00Z

March
12,
2004
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Offshore
and
Coastal
Oil
and
Gas
Extraction
Facilities
Seawater
Intake
Structure
Modification
Cost
Estimate
Mobile
Offshore
Drilling
Units
(
MODUs)

I.
Introduction
EPA
has
identified
mobile
offshore
drilling
units
(
MODUs)
as
an
Offshore
and
Coastal
Oil
and
Gas
Extraction
Facility
(
OCOGEF)
that
may
be
considered
for
coverage
by
the
Proposed
Phase
III
316(
b)
Rule.
There
are
a
number
of
different
types
of
MODUs
that
are
currently
operated.
These
include
jack­
ups,
semi­
submersibles,
drill
barges,
submersibles
and
drill
ships.
This
report
has
been
divided
up
into
the
various
types
of
vessels
to
investigate
the
possibilities
and
potential
costs
for
each
of
the
characteristic
seawater
intake
structures.

The
intent
of
this
analysis
is
to
develop
cost
estimates
for
new
and
existing
OCOGEFs
to
comply
with
the
proposed
Phase
III
316(
b)
rule.
These
facilities
have
not
previously
considered
the
reduction
of
fish
impingement
and
entrainment
on
MODUs
a
problem.
In
general,
there
is
little
or
no
specific
evidence
that
large
quantities
of
fish
are
being
drawn
up
into
the
intake
structures.
Consequently,
there
are
no
commonly
used
equipment
items
that
to
reduce
impingement
and/
or
entrainment
of
organisms.
This
report
has
developed
solutions
based
on
existing
technologies
to
reduce
impingement
and
entrainment.

The
capital
and
operation
and
maintenance
(
O
&
M)
costs
estimated
in
this
report
are
incremental
costs
for
the
facility.
A
10%
engineering
and
10%
contingency
have
been
included
in
the
cost
estimates.
An
allowance
of
6%
of
the
capital
cost
has
been
allowed
for
annual
parts
replacement
costs.
The
estimates
for
inspection
and
cleaning
periods
have
been
based
on
vendor
data
and
data
from
operators
of
similar
equipment
in
high
marine
growth
areas.
The
actual
costs
incurred
by
the
facility
will
vary
depending
on
operating
locations
and
duty
cycles.

With
the
use
of
equipment
external
to
the
existing
intake
structures
(
such
as
velocity
cap
technologies
and
fine
mesh
screens)
as
proposed
here,
the
existing
anti­
fouling
injection
systems
have
no
effect
on
the
potential
for
marine
growth
on
the
new
structures.
Biocides
are
injected
in
the
water
flow
inside
the
pipework
and
are
therefore
ineffective
on
any
intake
screen
or
cap
that
is
upstream
of
the
injection
point.
The
practice
of
recirculating
hot
water
back
through
the
intake
structure
to
achieve
a
"
hot
kill"
would
be
very
effective
at
preventing
bio
growth
throughout
the
system
including
any
screen
or
cap.
However,
it
is
not
assumed
that
this
is
typically
possible
for
the
MODU
facilities.
The
technologies
proposed
by
this
report
include
measures
required
to
limit
bio­
fouling
of
this
new
equipment.
It
should
be
noted
that
the
use
of
other
bio­
fouling
agents
to
protect
the
down
stream
pipework
will
still
be
required
as
per
standard
current
practice.

The
replacement
of
existing
once
through
cooling
water
systems
(
sea
water
intakes)
with
closed
loop
cooling
technologies
such
as
keel
cooling
and
air­
cooling
has
not
been
estimated
in
this
analysis.
The
degree
of
complexity
and
the
impact
to
the
onboard
process
equipment
makes
these
modifications
impossible
to
estimate
at
this
level.
The
International
Association
of
Drilling
Contractors
(
IADC)
reported
that
one
of
their
member's
jack­
up
rigs
converted
from
seawater
cooling
to
closed
loop
air­
cooling.
The
modification
cost
approximately
$
1.2
million,
and
resulted
in
loss
of
deck
space
and
a
small
loss
in
variable
March
12,
2004
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deck
load
(
equal
to
the
weight
of
the
coolers)
(
IADC
letter
to
EPA
by
Alan
Spackman
May
8,
2001).

A
key
assertion
that
has
been
made
throughout
the
following
report
is
that
production
losses,
vessel
movement
costs
and
dry­
dock
costs
are
not
included
in
the
cost
estimates.
If
the
modification
requires
dry­
docking
the
facility,
it
is
assumed
that
the
vessel
is
already
in
dry­
dock
for
routine
inspection,
maintenance
and
repairs
at
the
time
that
these
modifications
are
made.
IADC
prepared
an
estimate
of
$
16
million
to
dry
dock
a
latestgeneration
dynamically
positioned
drill
ship
operating
in
the
Gulf
of
Mexico
(
GOM).
The
key
issue
was
that
the
turn
around
time
(
from
GOM
to
Newport
News
and
back
to
GOM)
for
the
vessel
modification
was
in
the
order
of
66
days.
At
$
200k/
day
this
equates
to
over
$
13
million
in
lost
revenues
alone.
Other
costs
such
as
fuel,
removal
and
re­
fit
of
dynamic
positioning
thrusters
and
dry­
dock
facility
rental
push
the
cost
up
to
approximately
$
16
million.

Furthermore,
it
is
recognized
that
MODUs
may
not
enter
a
dry
dock
facility
for
as
long
as
10­
15
years.
Mandatory
inspections
of
the
hull
externals
may,
in
accordance
with
the
regulations,
be
undertaken
using
divers
or
Remotely
Operated
Vehicles
(
ROVs).
As
such,
the
only
reason
that
these
vessels
may
be
required
to
dry
dock
is
for
hull
painting,
major
maintenance,
or
vessel
re­
fit.

For
jackups,
cost
estimates
for
cooling
water
intake
structure
modification
were
developed
for
(
i)
submersible
pump
intakes
in
caissons
(
ii)
submersible
pump
intakes
without
caissons
and
(
iii)
Sea
chest
intakes,
located
at
the
bottom
or
side
of
the
MODU.
For
Submersibles,
Semi
Submersibles
and
Drill
Ships,
cost
estimates
were
developed
for
sea
chest
intakes,
located
at
the
bottom
or
side
of
the
MODU.
Though
Drill
Barges
may
have
sea
chest
or
simple
pipes
as
intake
mechanisms
for
cooling
water,
this
report
presents
cost
estimates
for
simple
pipe
intakes
only
based
on
available
data.

Details
of
the
cost
estimates
presented
in
this
report
are
in
Appendix
C.
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2004
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II.
Jackups
The
"
Jack
Up"
MODU
is
a
vessel
that
is
able
to
jack
its
hull
up
out
of
the
water
by
lowering
legs
down
to
the
sea
floor.
The
intent
of
this
is
to
provide
a
stable
and
positively
located
offshore
platform
for
exploration/
development
drilling.

Jack­
up
facilities
are
the
most
numerous
of
the
mobile
OCOGEFs
currently
operating
in
the
OCS.
There
are
in
the
order
of
140
currently
operating
in
the
Gulf
of
Mexico
(
GOM)
(
TDD
2001
6­
4).

Types
of
Sea
Water
Intake
Structures
Typical
intake
structures
for
Jackups
include:

A.
Jacked
down
structures
with
submersible
pumps
in
caissons
or
shrouds
B.
A
submersible
pump
simply
lowered
off
the
deck
into
the
water
without
caissons
or
shrouds,
and
C.
Sea
chests
in
the
hull.

Sea
chests
are
used
when
the
legs
are
retracted
and
the
vessel
hull
is
in
the
water
during
transport
or
during
set­
up/
pre­
load
at
location.
The
submersible
pumps
lowered
into
the
water
or
in
jacked
down
structures
are
used
when
the
MODU
is
in
location
and
in
the
jacked
up
position.
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2004
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Following
is
a
brief
discussion
of
the
various
types
of
intake
structures,
their
features
and
suitable
technologies
that
may
be
used
to
reduce
fish
entrainment
and
impingement.

A.
Jacked
Down
Intakes
with
Submersible
Pumps
in
Caissons
or
Shrouds
Jack­
up
platforms
commonly
use
submersible
pumps
that
are
located
on
structures
that
are
lowered
(
Jacked
Down)
into
the
water.
This
may
be
achieved
by
the
use
of
the
MODU
legs
or
a
stand­
alone
structure
(
Raw
Water
Tower).
March
12,
2004
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There
are
some
significant
characteristic
problems
associated
with
modifying
this
type
of
structure
including
the
following:

1.
The
caissons
form
an
integral
part
of
the
jack
down
structure
and
modifications
that
would
replace
the
lower
portion
of
the
caisson
would
be
very
difficult
and
expensive.

2.
Since
the
jack
down
structure
passes
through
the
hull
of
the
MODU,
there
are
restrictions
to
the
addition
of
equipment.
The
diagram
below
shows
how
the
raw
water
tower
structure
is
driven
and
guided
through
the
MODU
structure
 
limiting
the
envelop
for
any
modification.
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2004
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Raw
Water
Tower
Passing
through
Hull
and
Retained
Between
Guides
3.
The
intake
structures
can
be
retracted
into
the
hull
of
the
MODU
however,
the
retraction
is
typically
only
just
enough
for
the
structure
to
be
retained
within
the
hull.
As
such,
the
lower
structure
to
be
will
still
be
submerged
during
normal
movements
of
the
MODU.
For
some
long
haul
vessel
movements
the
MODU
is
lowered
onto
the
deck
of
a
special
ship
and
the
lower
raw
water
structure
would
be
clear
of
the
water,
however,
this
is
not
common.

Despite
the
limitations,
there
are
some
features
of
the
MODU
that
make
intake
modifications
in
open
water
possible.

1.
The
vessel
hull
is
lifted
out
of
the
water
and
scaffold
structures
"
over
the
side"
may
be
used
to
perform
maintenance
activities
and
intake
modifications,

2.
While
the
MODU
is
on
location
and
jacked
up,
the
intake
structure
can
be
easily
retracted
out
of
the
water
(
between
the
hull
and
sea
level).

Shutting
down
and
retracting
the
raw
water
tower
may
result
in
production
losses.
This
problem
may
be
overcome
by
using
a
secondary
source
of
cooling
water
such
as
a
submersible
pump
simply
lowered
into
the
water
(
refer
below
of
a
description
of
this
type
of
structure).
March
12,
2004
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Suitable
Technologies
for
Reducing
Impingement
and
Entrainment:

Technologies
that
would
be
suitable
for
use
on
this
type
of
intake
structure
include
the
fine
mesh
screen
and
velocity
cap
(
or
horizontal
flow
modifier)
technologies.
The
fine
mesh
screen
provides
a
physical
barrier
for
fish
whereas
the
velocity
cap
technology
utilises
the
behavioural
nature
of
fish
to
swim
against
a
horizontal
flow
(
minimise
entrainment).
Another
key
intention
is
to
limit
the
through
screen
velocity
to
0.5ft/
sec
or
less
so
that
it
is
low
enough
for
fish
to
swim
away
from
the
structure
(
minimise
impingement).
The
use
of
CuNi
alloys
and
air
sparging
is
a
suitable
technology
for
preventing
bio­
fouling
on
the
additional
equipment.

New
facilities
in
the
design
and
construction
phase
may
be
able
to
incorporate
"
off
the
shelf"
equipment
on
the
intake
structure.
Such
equipment
would
include
flanged
velocity
caps
and
cylindrical
fine
mesh
intake
screens.
The
raw
water
tower
design
would
have
to
change
slightly
to
allow
greater
retraction
into
the
vessel
hull
so
that
the
cap
or
screen
is
housed
inside
the
vessel
during
movements.
Also,
the
specific
structure
at
the
base
of
the
tower
would
need
to
allow
for
the
installation
of
the
cap
or
screen.

Existing
facilities
have
limitations
imposed
on
the
configuration
of
the
fine
mesh
screens/
velocity
caps
by
the
existing
jack
down
structure.
Specially
fabricated
equipment
is
required
to
overcome
these
limitations.

Cost
Estimate
for
Jackups
Using
Submersible
Pumps
in
Caissons
1.
Existing
Facilities
Generally
previous
cost
estimate
modules
have
been
set
up
for
individual
intakes.
In
this
case
however,
the
generic
intake
structure
will
consist
of
3
caisson
intakes
all
of
equal
size.
This
is
due
to
the
specific
design
and
constraints
of
this
type
of
equipment.
Furthermore,
in
this
case
it
is
easier
to
modify
all
three
structures
together
rather
than
individually.

It
must
be
noted
that
the
proposals
presented
in
this
analysis
are
just
a
few
possible
solutions
to
a
layout
with
many
other
possible
solutions
and
layouts.

Assumptions:

1.
Retraction
of
the
intake
structure
can
be
achieved
in
open
water
while
the
main
hull
is
jacked
up.
Therefore
there
is
no
need
for
dry­
docking
for
the
proposed
modifications
to
be
installed.
2.
This
cost
module
assumes
that
the
vessel
is
in
open
water
while
this
work
is
being
undertaken.
If
the
vessel
is
in
dry­
dock
for
other
works,
there
will
be
some
significant
savings
during
the
installation
of
the
required
equipment.
3.
It
is
assumed
that
the
addition
of
this
equipment
does
not
significantly
alter
the
structural
integrity
of
the
intake
structure
or
associated
equipment.
4.
No
production
loss
has
been
estimated
in
this
study.
It
is
envisaged
that
the
intake
structure
will
be
out
of
service
for
as
long
as
2
days
(
maximum)
for
this
modification
to
be
completed.
Alternative
sources
of
cooling
water
may
be
required
during
this
period.
This
may
be
achieved
with
the
use
of
submersible
pumps
simply
lowered
into
the
ocean
as
described
below.
5.
Installation
of
the
new
equipment
will
be
undertaken
with
the
use
of
a
boat
located
under
the
jacked
up
hull
and
scaffolding
off
the
intake
structure
as
required.
March
12,
2004
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6.
The
on
board
crew
numbers
can
be
boosted
by
an
additional
3
personnel
(
foreman,
welder
and
rigger/
scaffolder)
for
3
days
to
undertake
this
work
without
the
need
to
provide
additional
on
board
accommodation.
7.
The
following
personnel
costs
have
been
assumed:
Contract
labour
on
board
MODU:
Forman
$
70/
hr
Fitter
$
60/
hr
Rigger/
Scaffolder
$
60/
hr
Welder
$
60/
hr
Additional
Allowances:
$
100/
day
Contract
labour
on
shore:
Fitter/
Welder
$
40/
hr
Rigger/
Scaffolder
$
40/
hr
Painter
$
40/
hr
8.
Transportation
of
people
or
equipment
to
and
from
the
MODU
will
be
achieved
using
the
standard
scheduled
transport
(
helicopter
and
supply
vessel).
As
such,
no
allowance
has
been
made
for
transport
costs.
9.
The
estimate
has
been
assembled
based
on
caisson/
shroud
diameter.
The
bulk
flow
rate
through
the
pipe
is
assumed
to
be
3ft/
sec.
Intake
Size
Intake
Flow
Rate
10"
735GPM
(
1.060MGPD)
12"
1060GPM
(
1.525MGPD)
14"
1440GPM
(
2.075MGPD)
16"
1880GPM
(
2.710MGPD)
18"
2380GPM
(
3.425MGPD)
20"
2940GPM
(
4.230MGPD)
10.
Maintenance
cost
includes
by­
annual
inspections
and
manual
cleaning
of
surfaces.
This
involves
retracting
the
intake
structure
while
the
MODU
hull
is
jacked
up
out
of
the
water.
A
maintenance
crew
on
board
a
boat
will
be
able
to
access
the
intake
under
the
rig.
This
is
expected
to
be
a
relatively
short
duration
event
and
no
production
losses
have
been
estimated.
11.
A
fixed
annual
expense
cost
of
6%
of
initial
capital
cost
has
been
applied
to
this
equipment
to
estimate
ongoing
repairs
and
replacement
of
static
equipment.
12.
In
the
case
that
air
sparging
has
been
incorporated,
it
is
assumed
that
the
area
is
available
on
the
deck
for
the
air
sparging
equipment
(
a
receiver
and
some
control
valves).
13.
The
operation
cost
for
air
sparging
has
been
calculated
based
on
7
airbursts
per
day
(
medium
debris
in
the
water).
The
cost
of
power
to
the
compressor
has
been
assumed
to
be
$
0.04/
kWhr.
14.
It
is
assumed
that
on
board
personnel
will
undertake
the
maintenance
and
inspection
of
the
new
intake
equipment.
As
such,
no
man
hour
or
day
rate
has
been
applied
however
a
rate
for
a
boat
that
requires
2
days
travel
to
and
from
the
facility
plus
1
day
at
the
facility
has
been
used.
The
personnel
from
the
facility
would
board
the
boat
when
it
arrives
at
the
rig
to
gain
access
under
the
hull.

Description
of
Retrofit
Modification:

The
basic
modification
proposed
by
this
study
is
that
the
lower
section
of
the
intake
structure
may
be
enclosed
using
3
panels
of
fine
mesh
screen
or
horizontal
flow
modifiers
to
achieve
the
required
fish
protection.
The
top
and
bottom
sections
of
this
new
structure
would
be
made
from
plate
steel.
The
intake
panels
would
be
removable
for
ease
of
maintenance.
This
arrangement
creates
a
single
intake
structure
that
all
three
intake
pipes
would
draw
seawater.
March
12,
2004
­
Page
9
of
40
Note:
The
horizontal
flow
modifier
is
a
panel
that
ensures
horizontal
flow
into
the
intake
structure
at
a
velocity
of
0.5ft/
sec
or
less.
This
is
a
derivative
of
the
velocity
cap
technology.

A
detailed
cost
estimate
has
been
assembled
for
modifying
a
raw
water
tower
consisting
of
3
off
16"
main
pipes
equally
spaced
at
3'
3".
These
dimensions
were
based
on
drawings
of
a
16"
triangular
trussed
raw
water
tower
supplied
by
Transocean
(
Hull
P1092,
Drawing
H­
17).
The
costs
for
other
intake
sizes
have
been
estimated
based
on
this
detailed
estimate.

Typical
Section
through
the
Raw
Water
Tower
Typical
Lower
Section
of
the
Raw
Water
Tower
Notes:
1.
The
lower
portions
of
the
pipes
making
up
the
raw
water
tower
are
slotted
(
approximately
69"
 
1752mm
up
the
pipe)
on
the
sides
and
bottom
is
open.
March
12,
2004
­
Page
10
of
40
Other
configurations
include
slotted
sides
but
capped
on
the
bottom
and
open
at
the
bottom
with
no
slots
in
the
sides).
2.
The
geometry
of
the
structural
bracing
(
flush
with
the
outside
perimeter
of
the
tower)
in
this
example
helps
support
the
screen
face.
If
the
bracing
structure
is
inside
the
tangent
line
of
the
pipes,
a
small
modification
would
be
required
to
support
the
proposed
screen
frame.

Elevation
of
Proposed
Raw
Water
Tower
Enclosure
Plan
of
Section
Through
Raw
Water
Tower
Enclosure
Notes:
1.
Slots
in
the
raw
water
tower
that
are
close
or
outside
the
fish
barrier
must
be
plugged
to
prevent
fish
entrainment
and
impingement.
2.
Slots
inside
the
structural
bracing
need
to
be
enlarged
to
compensate
for
the
plugged
holes.
3.
In
the
case
that
the
lower
sections
are
open,
cut
scallops
out
of
the
bottom
of
the
pipe.
The
scalloped
opening
must
be
cut
to
have
an
equivalent
open
area
as
the
open
pipe.
Also,
some
vertical
slots
should
be
cut
into
the
intake
side
to
minimise
head
loss
and
assist
flow
distribution.
4.
Care
needs
to
be
taken
to
avoid
damaging
the
submersible
pump
and
the
supports
for
the
pump
inside
the
pipe.
5.
The
cost
for
this
work
is
calculated
based
on
the
hourly
rate
of
the
personnel
assigned
to
the
job.
Enclosure
Fish
Barrier
Enlarge
slots
on
internal
of
raw
water
tower
Plug
holes
in
raw
water
tower
to
prevent
impingement
and
entrainment
March
12,
2004
­
Page
11
of
40
6.
The
screen
area
proposed
here
will
achieve
a
through
screen
velocity
significantly
lower
than
the
0.5ft/
sec
required.
7.
Air
sparging
may
be
added
to
this
design
using
the
raw
water
tower
to
mount
the
supply
pipework.
It
has
been
assumed
that
the
area
is
available
on
the
deck
for
the
air
sparging
equipment
(
a
receiver
and
some
control
valves).
The
cost
of
the
air
sparge
system
has
been
based
on
the
systems
used
for
fine
mesh
screens
of
a
similar
bulk
flow
rate.
Intake
Size
Hydro­
burst
System
Size
10"
120
Gallon
(
2
Hp)
12"
120
Gallon
(
2
Hp)
14"
200
Gallon
(
3.5
Hp)
16"
200
Gallon
(
3.5
Hp)
18"
280
Gallon
(
5
Hp)
20"
280
Gallon
(
5
Hp)

Top
Plate
of
Enclosure
Bottom
Plate
of
Enclosure
Banded
Fine
Mesh
Screen
Horizontal
Flow
Modifier
Notes:
1.
For
simplicity,
the
brackets
and
ancillary
equipment
has
not
been
shown
here
but
has
been
included
in
the
cost
estimate.
2.
The
horizontal
flow
modifier
uses
4"
vanes
separated
2"
apart
from
one
another.
They
ensure
that
the
flow
is
predominantly
horizontal.
March
12,
2004
­
Page
12
of
40
3.
Since
air
sparging
is
not
required
for
velocity
cap
installations.
Air
sparging
of
the
horizontal
flow
modifier
has
not
been
included
in
this
cost
module.

Proposed
Installation
Method:
1.
Personnel
to
undertake
the
works
will
be
flown
to
the
rig
on
the
standard
crew
change
helicopter
and
flown
back
to
shore
on
the
next
change
of
crew.
Two
helicopters
per
week
are
assumed
for
crew
change
 
one
every
3
days.
2.
Three
personnel
(
a
foreman,
welder
and
rigger)
will
be
required
to
undertake
the
work
and
will
be
at
the
rig
for
3
12­
hour
shifts
plus
2
additional
shifts
for
the
mobilization
and
demobilization
(
5
shifts
in
total).
The
actual
work
should
take
less
than
two
12­
hour
shifts.
3.
Good
weather
(
calm)
is
assumed
during
the
construction
works.
4.
A
boat
with
a
sufficient
deck
area
will
be
used
to
access
the
structure.
The
size
and
cost
of
this
vessel
will
be
assumed
to
be
similar
to
a
commercial
dive
boat.
5.
It
is
assumed
that
the
boat
will
require
2
days
to
travel
to
and
from
the
rig.
Three
days
at
the
rig
has
been
allowed
for
the
preparation
and
construction
process.
6.
All
components
fabricated
on
shore
and
transported
to
site
using
the
boat.
7.
The
installation
crew
will
use
the
boat
as
a
construction
platform
plus
they
will
be
required
to
build
some
scaffolding
off
the
raw
water
tower.
8.
Preparation
of
the
raw
water
tower
shutdown
will
include
the
use
of
submersible
pumps
lowered
into
the
seawater
to
supply
the
seawater
cooling
system.
No
allowance
has
been
made
for
this
work
or
extra
equipment.
9.
The
actual
shutdown
of
raw
water
tower
will
take
between
1
and
2
days.

Operation
and
maintenance
costs:
1.
Onboard
personnel
will
carry
out
all
operation,
inspection
and
maintenance
work.
The
cost
estimate
has
been
based
on
$
60/
hr
MODU
labour
rates.
2.
Operation
costs
of
the
system
include
the
supply
of
power
to
the
air
sparging
system
for
normal
operation.
The
frequency
of
air
sparge
operation
is
dependant
on
the
quantity
of
debris
in
the
water.
This
frequency
ranges
from
once
per
week
to
once
an
hour.
Since
the
vessel
is
mobile
and
all
types
of
water
may
be
encountered,
it
is
assumed
that
the
air
sparge
system
is
automatically
operated
every
hour
(
24
times
a
day).
Furthermore,
it
is
assumed
that
the
accumulator
takes
0.5
hours
to
re­
charge
after
an
air
burst
event.
3.
Based
on
vendor
information,
routine
inspection
and
maintenance
requirements
for
the
air
sparging
system
have
been
estimated
based
on
3
hours
per
week
for
all
system
sizes.
4.
Inspection
intervals
for
fine
mesh
screens
and
horizontal
flow
modifiers
are
assumed
to
be
one
per
year.
This
has
been
based
on
typical
inspection
frequencies
for
onshore
and
coastal
facilities.
5.
The
costs
of
inspection
and
maintenance
of
the
raw
water
tower
intake
structure
includes
the
cost
of
boat
rental
to
get
to
the
underside
of
the
hull
while
the
structure
is
jacked
up
out
of
the
water.
6.
A
cost
of
$
1250/
day
has
been
allowed
for
the
hire
of
a
boat,
skipper
and
crew.
Two
days
mobilization
from
port
to
the
rig,
one
day
at
the
rig
and
two
days
return
to
port
have
been
allowed
in
the
cost
estimate.
7.
6%
of
the
capital
cost
has
been
allowed
for
annual
parts
replacement
cost.

Table
1
below
presents
the
capital
and
O
&
M
cost
estimates
for
modifying
existing
caisson
intake
structures
using
the
retrofit
options
proposed
above.
March
12,
2004
­
Page
13
of
40
Table
1.
Capital
and
O
&
M
Cost
Estimates
for
Caisson
Intake
Modification
of
Existing
Jackup
Facilities
Stainless
Steel
Fine
Mesh
Screens:
No
Additional
Anti­
Fouling
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Structure
Annual
O&
M
Cost
per
Structure
10"
Raw
Water
Tower
Assembly
$
37,244
$
7,421
12"
Raw
Water
Tower
Assembly
$
38,613
$
7,503
14"
Raw
Water
Tower
Assembly
$
39,982
$
7,585
16"
Raw
Water
Tower
Assembly
$
41,351
$
7,667
18"
Raw
Water
Tower
Assembly
$
42,720
$
7,749
20"
Raw
Water
Tower
Assembly
$
44,089
$
7,831
Stainless
Steel
Fine
Mesh
Screens:
Air
Sparge
Anti­
Fouling
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Structure
Annual
O&
M
Cost
per
Structure
10"
Raw
Water
Tower
Assembly
$
66,819
$
9,493
12"
Raw
Water
Tower
Assembly
$
68,188
$
9,575
14"
Raw
Water
Tower
Assembly
$
72,222
$
10,027
16"
Raw
Water
Tower
Assembly
$
73,591
$
10,110
18"
Raw
Water
Tower
Assembly
$
79,770
$
10,691
20"
Raw
Water
Tower
Assembly
$
81,139
$
10,773
CuNi
Fine
Mesh
Screens:
No
Additional
Anti­
Fouling
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Structure
Annual
O&
M
Cost
per
Structure
10"
Raw
Water
Tower
Assembly
$
38,743
$
7,511
12"
Raw
Water
Tower
Assembly
$
40,412
$
7,611
14"
Raw
Water
Tower
Assembly
$
42,080
$
7,711
16"
Raw
Water
Tower
Assembly
$
43,749
$
7,811
18"
Raw
Water
Tower
Assembly
$
45,418
$
7,911
20"
Raw
Water
Tower
Assembly
$
47,086
$
8,011
CuNi
Fine
Mesh
Screens:
Air
Sparge
Anti­
Fouling
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Structure
Annual
O&
M
Cost
per
Structure
10"
Raw
Water
Tower
Assembly
$
68,318
$
9,583
12"
Raw
Water
Tower
Assembly
$
69,987
$
9,683
14"
Raw
Water
Tower
Assembly
$
74,320
$
10,153
16"
Raw
Water
Tower
Assembly
$
75,989
$
10,253
18"
Raw
Water
Tower
Assembly
$
82,468
$
10,852
20"
Raw
Water
Tower
Assembly
$
84,136
$
10,952
Horizontal
Flow
Modifier
Horizontal
Flow
Modifier
Initial
Capital
Cost
per
Structure
Annual
O&
M
Cost
per
Structure
10"
Raw
Water
Tower
Assembly
$
41,461
$
7,674
12"
Raw
Water
Tower
Assembly
$
43,673
$
7,806
14"
Raw
Water
Tower
Assembly
$
45,885
$
7,939
16"
Raw
Water
Tower
Assembly
$
48,097
$
8,072
18"
Raw
Water
Tower
Assembly
$
50,310
$
8,205
20"
Raw
Water
Tower
Assembly
$
52,522
$
8,337
March
12,
2004
­
Page
14
of
40
2.
New
Facilities
New
facilities
with
submersible
pumps
in
caisson
for
cooling
water
intake
have
the
advantage
that
they
have
unlimited
design
possibilities.
In
the
case
that
"
off
the
shelf"
equipment
is
used,
the
cost
estimates
for
simple
pipes
and
caissons
 
new
facilities
are
valid
for
the
single
intakes
(
3
per
raw
water
tower).
It
is
worth
noting
that
if
these
"
off
the
shelf"
technologies
are
used,
there
may
need
to
be
other
design
changes
made
to
the
facility
so
that
the
raw
water
tower
structure
may
be
adequately
retracted
into
the
hull
during
transportation.
This
modification
to
the
hull
would
require
the
lower
guide
assembly
be
relocated
in
the
hull.
The
diagrams
below
show
the
existing
arrangements
for
lower
guides
and
the
new
arrangement
that
would
be
required
if
"
Off
the
Shelf"
screens
and
velocity
caps
were
used.
It
is
recognised
that
the
cost
of
hull
modification
and
additional
raw
water
tower
stiffening
may
be
significant.
An
estimate
for
this
work
has
not
been
included
in
this
cost
module.

Please
refer
to
the
existing
facility
cost
module
above
for
the
O&
M
allowances
and
assumptions
that
have
been
made.

Typical
Jack
Down
Raw
Water
Tower
with
Upper
and
Lower
Guide
Arrangement
Jack­
up
Hull
Jack
Down
Drive
Upper
Guides
Lower
Guides
Jack­
up
Hull
Jack
Down
Raw
Water
Tower
March
12,
2004
­
Page
15
of
40
Typical
Jack
Down
Raw
Water
Tower
with
"
Off
The
Shelf"
Fine
Mesh
Screens
and
New
Lower
Guide
Arrangement
Notes:
1.
More
stiffening
in
the
raw
water
tower
would
be
required
to
accommodate
the
closer
guide
positions.
2.
A
velocity
cap
installation
would
require
a
similar
lower
guide
modification.

The
following
costs
have
been
assembled
to
install
fine
mesh
screens
and
velocity
caps
on
the
lower
section
of
the
raw
water
tower.
The
tower
is
assumed
to
have
three
pump
caissons.
The
costs
stated
below
include
the
cost
of
the
screen
and
an
allowance
for
the
installation
and
bolt
up
of
a
flange
connection.
Other
hull
and
raw
water
tower
design
modifications,
if
required,
are
not
included
in
this
estimate.
Capital
and
O
&
M
cost
estimates
for
modifying
caisson
intake
structures
of
new
facilities
using
off­
the­
shelf
equipment
are
presented
in
Table
2.

Table
2.
Capital
and
O
&
M
Cost
Estimates
for
Caisson
Intake
Modification
of
New
Jackup
Facilities
Using
Off­
the­
Shelf
Equipment
Stainless
Steel
Fine
Mesh
Screens:
No
Additional
Anti­
Fouling
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Structure
Annual
O&
M
Cost
per
Structure
10"
Raw
Water
Tower
Assembly
$
9,214
$
7,563
12"
Raw
Water
Tower
Assembly
$
11,657
$
7,709
14"
Raw
Water
Tower
Assembly
$
14,339
$
7,870
16"
Raw
Water
Tower
Assembly
$
16,512
$
8,001
18"
Raw
Water
Tower
Assembly
$
17,185
$
8,041
20"
Raw
Water
Tower
Assembly
$
22,478
$
8,359
Jack­
up
Hull
Jack
Down
Drive
Upper
Guides
New
Lower
Guide
Location
Jack­
up
Hull
Jack
Down
Raw
Water
Tower
with
extra
Stiffening
"
Off
the
Shelf"
Fine
Mesh
Screens
March
12,
2004
­
Page
16
of
40
Stainless
Steel
Fine
Mesh
Screens:
Air
Sparge
Anti­
Fouling
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Structure
Annual
O&
M
Cost
per
Structure
10"
Raw
Water
Tower
Assembly
$
31,964
$
9,226
12"
Raw
Water
Tower
Assembly
$
34,407
$
9,372
14"
Raw
Water
Tower
Assembly
$
38,389
$
9,821
16"
Raw
Water
Tower
Assembly
$
40,562
$
9,952
18"
Raw
Water
Tower
Assembly
$
48,580
$
10,643
20"
Raw
Water
Tower
Assembly
$
53,873
$
10,961
CuNi
Fine
Mesh
Screens:
No
Additional
Anti­
Fouling
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Structure
Annual
O&
M
Cost
per
Structure
10"
Raw
Water
Tower
Assembly
$
14,914
$
7,905
12"
Raw
Water
Tower
Assembly
$
17,927
$
8,086
14"
Raw
Water
Tower
Assembly
$
22,499
$
8,360
16"
Raw
Water
Tower
Assembly
$
25,842
$
8,561
18"
Raw
Water
Tower
Assembly
$
26,485
$
8,599
20"
Raw
Water
Tower
Assembly
$
35,228
$
9,124
CuNi
Fine
Mesh
Screens:
Air
Sparge
Anti­
Fouling
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Structure
Annual
O&
M
Cost
per
Structure
10"
Raw
Water
Tower
Assembly
$
37,664
$
9,568
12"
Raw
Water
Tower
Assembly
$
40,677
$
9,748
14"
Raw
Water
Tower
Assembly
$
45,249
$
10,233
16"
Raw
Water
Tower
Assembly
$
48,592
$
10,434
18"
Raw
Water
Tower
Assembly
$
49,235
$
10,682
20"
Raw
Water
Tower
Assembly
$
57,978
$
11,207
Velocity
Cap
Stainless
Steel
Velocity
Cap
Initial
Capital
Cost
per
Structure
Annual
O&
M
Cost
per
Structure
10"
Raw
Water
Tower
Assembly
$
76,714
$
11,613
12"
Raw
Water
Tower
Assembly
$
77,057
$
11,633
14"
Raw
Water
Tower
Assembly
$
77,399
$
11,654
16"
Raw
Water
Tower
Assembly
$
77,742
$
11,675
18"
Raw
Water
Tower
Assembly
$
78,085
$
11,695
20"
Raw
Water
Tower
Assembly
$
78,428
$
11,716
CuNi
Velocity
Cap
Initial
Capital
Cost
per
Structure
Annual
O&
M
Cost
per
Structure
10"
Raw
Water
Tower
Assembly
$
76,714
$
11,613
12"
Raw
Water
Tower
Assembly
$
77,057
$
11,633
14"
Raw
Water
Tower
Assembly
$
77,399
$
11,654
16"
Raw
Water
Tower
Assembly
$
77,742
$
11,675
18"
Raw
Water
Tower
Assembly
$
78,085
$
11,695
20"
Raw
Water
Tower
Assembly
$
78,428
$
11,716
The
existing
facility
retrofit
solutions
presented
above
may
be
installed
as
new
equipment
during
the
design
and
construction
phase
of
the
rig.
The
advantage
of
this
approach
is
that
existing
designs
of
raw
water
towers
may
be
used
with
only
very
minor
modification.
The
cost
estimates
shown
in
Table
3
below
are
for
the
new
facilities
of
the
March
12,
2004
­
Page
17
of
40
proposed
raw
water
tower
modification
described
in
the
preceding
paragraphs.
Unlike
the
cost
estimates
shown
in
Table
2,
where
off­
the­
shelf
equipment
is
used
for
new
facilities,
the
estimates
in
Table
3
are
for
retrofit
options,
applied
to
new
facilities.
For
assumptions
please
refer
to
the
Existing
Facility
modifications
described
above.

Table
3.
Capital
and
O
&
M
Costs
for
New
Facility
Caisson
Intake
Using
Retrofit
Options
for
Jackups
Stainless
Steel
Fine
Mesh
Screens:
No
Additional
Anti­
Fouling
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Intake
Annual
O&
M
Cost
per
Structure
10"
Raw
Water
Tower
Assembly
$
8,239
$
7,421
12"
Raw
Water
Tower
Assembly
$
9,887
$
7,503
14"
Raw
Water
Tower
Assembly
$
11,535
$
7,585
16"
Raw
Water
Tower
Assembly
$
13,183
$
7,667
18"
Raw
Water
Tower
Assembly
$
14,831
$
7,749
20"
Raw
Water
Tower
Assembly
$
16,479
$
7,831
Stainless
Steel
Fine
Mesh
Screens:
Air
Sparge
Anti­
Fouling
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Intake
Annual
O&
M
Cost
per
Structure
10"
Raw
Water
Tower
Assembly
$
37,814
$
9,493
12"
Raw
Water
Tower
Assembly
$
39,462
$
9,575
14"
Raw
Water
Tower
Assembly
$
43,775
$
10,027
16"
Raw
Water
Tower
Assembly
$
45,423
$
10,110
18"
Raw
Water
Tower
Assembly
$
51,881
$
10,691
20"
Raw
Water
Tower
Assembly
$
53,529
$
10,773
CuNi
Fine
Mesh
Screens:
No
Additional
Anti­
Fouling
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Intake
Annual
O&
M
Cost
per
Structure
10"
Raw
Water
Tower
Assembly
$
9,738
$
7,511
12"
Raw
Water
Tower
Assembly
$
11,686
$
7,611
14"
Raw
Water
Tower
Assembly
$
13,633
$
7,711
16"
Raw
Water
Tower
Assembly
$
15,581
$
7,811
18"
Raw
Water
Tower
Assembly
$
17,529
$
7,911
20"
Raw
Water
Tower
Assembly
$
19,476
$
8,011
CuNi
Fine
Mesh
Screens:
Air
Sparge
Anti­
Fouling
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Intake
Annual
O&
M
Cost
per
Structure
10"
Raw
Water
Tower
Assembly
$
39,313
$
9,583
12"
Raw
Water
Tower
Assembly
$
41,261
$
9,683
14"
Raw
Water
Tower
Assembly
$
45,873
$
10,153
16"
Raw
Water
Tower
Assembly
$
47,821
$
10,253
18"
Raw
Water
Tower
Assembly
$
54,579
$
10,852
20"
Raw
Water
Tower
Assembly
$
56,526
$
10,952
Horizontal
Flow
Modifier:
No
Additional
Anti­
Fouling
Horizontal
Flow
Modifier
Initial
Capital
Cost
per
Intake
Annual
O&
M
Cost
per
Structure
10"
Raw
Water
Tower
Assembly
$
12,456
$
7,674
12"
Raw
Water
Tower
Assembly
$
14,947
$
7,806
March
12,
2004
­
Page
18
of
40
14"
Raw
Water
Tower
Assembly
$
17,438
$
7,939
16"
Raw
Water
Tower
Assembly
$
19,929
$
8,072
18"
Raw
Water
Tower
Assembly
$
22,421
$
8,205
20"
Raw
Water
Tower
Assembly
$
24,912
$
8,337
B.
Submersible
Pump
Intakes
Without
Caissons
or
Shrouds
Pump
Installation
Arrangement
Typical
Submersible
Pump
This
type
of
pumping
arrangement
is
relatively
simple.
The
submersible
pump
is
made
to
be
robust
enough
to
be
simply
lowered
into
the
water.
A
flexible
pipe
or
combination
of
flexible
and
rigid
pipe
is
used
to
pipe
the
water
back
on
board
the
MODU.
It
is
common
practice
for
these
pumps
to
be
raise
and
lowered
into
the
water.
As
such,
installation,
inspection
and
maintenance
of
new
equipment
to
prevent
fish
entrainment
and
impingement
is
very
simple.

Possible
solutions
that
may
be
employed
include
a
simple
fine
mesh
screen
over
the
pump
suction
or
a
velocity
cap
over
the
suction.
The
photo
above
of
a
submersible
pump
shows
the
pump
sitting
on
its
suction
inlet.
The
fine
mesh
or
velocity
cap
may
be
simply
bolted
or
clamped
to
the
pump
body.
The
design
of
this
new
equipment
would
have
to
take
into
account
the
weight
of
the
pump
and
other
ancillary
equipment
of
pipe.
Also,
the
pump
would
stand
taller
when
it
is
on
the
deck.
Storage
and
access
issues
may
also
need
to
be
resolved
with
the
implementation
of
these
technologies.

Other
solutions
may
include
placing
the
pump
in
a
basket
made
with
fine
mesh
screens.
This
solution
may
provide
the
pump
with
some
additional
protection
from
being
damaged
by
impact.
This
option
has
not
been
costed
for
this
module.

Cost
Estimate
for
Jackups
Using
Submersible
Pumps
Without
Caisson
for
Intake
1.
Existing
and
New
Facilities
There
is
essentially
no
difference
between
the
new
and
existing
facility
costs
for
this
arrangement.
An
interview
with
a
supplier
of
fine
mesh
screens
indicated
that
this
equipment
is
purchased
to
suit
the
required
pump
and
will
be
supplied
to
simply
bolt
March
12,
2004
­
Page
19
of
40
on
to
the
submersible
pump
suction.
As
such,
the
capital
costs
of
"
off
the
shelf"
fine
mesh
screens
are
presented
in
Table
4
to
give
an
indication
of
the
cost
of
this
modification.
"
Off
the
shelf"
velocity
caps
are
also
available
but
the
costing
information
currently
available
suggests
that
the
cost
for
the
velocity
cap
is
constant
for
all
of
the
typical
intake
sizes
below.
Annual
maintenance
costs
have
been
estimated
to
include
6%
of
capital
for
replacement
and
repairs
plus
8
maintenance
hours
(
at
$
60
per
hour)
per
year
for
inspection
and
cleaning.

Table
4.
Capital
and
O
&
Costs
of
Off­
the­
Shelf
Equipment
for
Submersible
Pump
Intake
Modification
for
Jackups
Stainless
Steel
Fine
Mesh
Screen:
Capital
Cost
Annual
O&
M
Cost
10"
Pump
Suction
Diameter
$
2,500
$
630
12"
Pump
Suction
Diameter
$
3,200
$
672
14"
Pump
Suction
Diameter
$
3,980
$
719
16"
Pump
Suction
Diameter
$
4,590
$
755
18"
Pump
Suction
Diameter
$
4,700
$
762
20"
Pump
Suction
Diameter
$
6,350
$
861
CuNi
Fine
Mesh
Screen:
Capital
Cost
Annual
O&
M
Cost
10"
Pump
Suction
Diameter
$
4,400
$
744
12"
Pump
Suction
Diameter
$
5,290
$
797
14"
Pump
Suction
Diameter
$
6,700
$
882
16"
Pump
Suction
Diameter
$
7,700
$
942
18"
Pump
Suction
Diameter
$
7,800
$
948
20"
Pump
Suction
Diameter
$
10,600
$
1,116
Stainless
Steel
Velocity
Cap:
Capital
Cost
Annual
O&
M
Cost
All
10"
to
20"
Pump
Suction
Diameters
$
25,000
$
1,980
CuNi
Velocity
Cap:
Capital
Cost
Annual
O&
M
Cost
All
10"
to
20"
Pump
Suction
Diameters
$
25,000
$
1,980
C.
Sea
Chest
Intakes
In
the
Hull
Jack
up
MODUs
use
sea
chests
for
cooling
water
intakes
during
vessel
movements
­
the
legs
are
retracted
and
the
hull
is
in
the
water.
During
this
time,
the
raw
water
tower
is
also
typically
retracted
and
all
of
the
cooling
water
is
obtained
from
sea
chests
in
the
hull.

While
the
hull
is
jacked
up
out
of
the
water,
the
sea
chest
is
fully
exposed,
inoperable
and
accessible
via
scaffolding.
This
feature
makes
it
possible
to
modify
the
sea
chests
while
the
vessel
is
on
location
in
the
middle
of
the
ocean
and
during
normal
production.
Although
it
is
better
to
make
any
modification
to
a
vessel
while
it
is
in
design
or
under
construction
it
is
possible
to
retrofit
the
modifications
required
to
the
sea
chests
without
the
need
to
return
to
a
dry
dock.

Specific
details
of
the
jack
up
sea
chests
are
not
currently
available,
however
the
following
arrangements
have
been
assumed:
March
12,
2004
­
Page
20
of
40
Generic
Sea
Chest
Arrangement
in
the
Hull
Side
Wall
Generic
Sea
Chest
Arrangement
in
the
Hull
Bottom
Suitable
Technologies
for
Reducing
Impingement
and
Entrainment:

Technologies
that
would
be
suitable
for
use
on
this
type
of
intake
structure
include
the
fine
mesh
screen
and
velocity
cap
(
or
horizontal
flow
modifier)
technologies.
The
fine
mesh
screen
provides
a
physical
barrier
for
fish
whereas
the
velocity
cap
technology
utilises
the
behavioural
nature
of
fish
to
swim
against
a
horizontal
flow
(
minimise
entrainment).
Another
key
intention
is
to
limit
the
through
screen
velocity
to
0.5ft/
sec
or
less
so
that
it
is
low
enough
for
fish
to
swim
away
from
the
structure
(
minimise
impingement).
The
use
of
CuNi
alloys
and
air
sparging
is
a
suitable
technology
for
preventing
bio­
fouling
on
the
additional
equipment.

Air
sparging
will
be
ineffective
on
sea
chests
located
on
the
bottom
of
the
vessel
and
problematic
on
sidewall
sea
chests
(
due
to
air
entrainment
in
the
intake).
As
such,
the
air
sparging
technology
is
not
presented
for
these
intake
structure
modifications.
Pump
Header
External
Coarse
Screen
Screen
Box
with
removable
lid
Isolation
Valves
Vessel
Hull
Side
Wall
Fine
Screen
Pump
Header
External
Coarse
Screen
Screen
Box
with
removable
lid
Isolation
Valves
Vessel
Bottom
Hull
Fine
Screen
Inboard
Outboard
Inboard
Outboard
March
12,
2004
­
Page
21
of
40
The
retrofit
structures
proposed
here
are
basically
added
on
to
the
existing
intake
structure.
In
order
to
reduce
the
intake
velocity
to
0.5
ft/
sec
or
less,
the
area
that
the
seawater
is
drawn
into
the
intake
has
to
be
a
minimum
size.
It
is
assumed
that
the
existing
structure
has
a
through
screen
velocity
greater
than
the
0.5ft/
sec
required
and
a
modification
is
required
to
increase
the
screen
area.

One
solution
may
include
cutting
large
holes
in
the
hull
to
increase
the
intake
size.
This
solution
is
not
presented
as
a
retrofit
option
for
existing
facilities
in
this
report
as
this
would
require
specific
vessel
drawings
to
define
the
modification.
However,
this
would
be
an
ideal
way
to
ensure
the
desired
through
screen
velocity
at
the
design
and
construction
phase.

Possible
sea
chest
modifications
include
a
fine
mesh
screen
mounted
on
a
flow
diffuser
box
that
is
welded
to
the
hull.
Alternatively,
a
horizontal
flow
modifier
arrangement
may
be
used.
This
intake
arrangement
uses
the
velocity
cap
technology
to
achieve
horizontal
flow
into
the
intake.

Assumptions:
1.
The
sea
chests
are
accessible
via
scaffold
when
the
hull
is
jacked
out
of
the
water.
Therefore,
dry­
docking
of
the
vessel
is
not
required.
2.
A
single
sea
chest
is
assumed
for
the
vessel.
Conservative
estimates
for
multiple
sea
chests
may
be
obtained
by
multiplying
the
costs
below
by
the
number
of
intakes.
There
will
however
be
savings
in
construction
with
multiple
intakes.
3.
The
estimate
has
been
assembled
based
on
sea
chest
flow
rate.
Intake
Flow
Rate
Equivalent
Pipe
Diameter
(@
~
3ft/
sec)
1500GPM
(
2.160MGPD)
14
3000GPM
(
4.320MGPD)
20
4500GPM
(
6.480MGPD)
25
6000GPM
(
8.640MGPD)
28
Operation
and
maintenance
costs:
1.
Onboard
personnel
will
carry
out
all
operation,
inspection
and
maintenance
work.
The
cost
estimate
has
been
based
on
$
60/
hr
MODU
labour
rates
for
a
period
of
16
hours
per
year
on
maintenance
personnel.
2.
Inspection
intervals
for
fine
mesh
screens
and
horizontal
flow
modifiers
are
assumed
to
be
one
per
year.
This
has
been
based
on
typical
inspection
frequencies
for
onshore
and
coastal
facilities.
3.
The
costs
of
inspection
and
maintenance
of
the
sea
chest
intake
structure
includes
40
hours
of
scaffolders
time
to
get
to
the
underside
of
the
hull
while
the
structure
is
jacked
up
out
of
the
water.
4.
6%
of
the
capital
cost
has
been
allowed
for
annual
parts
replacement
cost.

Cost
Estimate
for
Sea
Chest
Intakes
in
the
Hull
1.
Existing
Facilities
Description
of
Protruding
Fine
Mesh
Screen
Retrofit
Modification:

Please
refer
to
Appendix
A
for
the
Protruding
Fine
Mesh
Screen
Modification
drawings/
sketches.
A
detailed
cost
estimate
has
been
assembled
based
on
the
dimensions
calculated
for
a
4500GPM
(~
1000kl/
hr)
intake.
The
costs
for
other
intake
sizes
have
been
estimated
based
on
this
4500GPM
sea
chest
estimate.
March
12,
2004
­
Page
22
of
40
The
protruding
fine
mesh
screen
option
is
a
low
profile
addition
welded
to
the
outside
of
the
hull
over
the
existing
intake
structure.
For
the
4500GPM
module,
the
addition
protrudes
approximately
5"
out
from
the
hull
and
includes
a
50"
by
100"
intake
screen
(
Item
2
Appendix
A).
An
even
flow
across
the
fine
mesh
screen
is
achieved
by
the
installation
of
a
flow
diffuser
inside
the
new
structure
between
the
existing
intake
and
the
screen
(
Item
3
Appendix
A).
Steel
bars
are
mounted
on
the
outside
of
the
fine
mesh
screen
to
protect
against
damage
(
Item
1
Appendix
A).
These
items
are
assembled
on
a
main
frame
that
is
welded
to
the
hull
of
the
vessel
(
Item
5
Appendix
A).

Proposed
Installation
Method:
1.
Personnel
to
undertake
the
works
will
be
flown
to
the
rig
on
the
standard
crew
change
helicopter
and
flown
back
to
shore
on
the
next
change
of
crew.
Two
helicopters
per
week
are
assumed
for
crew
change
 
one
every
3
days.
2.
Four
personnel
(
a
foreman,
two
welders
and
rigger)
will
be
required
to
undertake
the
work
and
will
be
at
the
rig
for
7
12­
hour
shifts
plus
2
additional
shifts
for
the
mobilization
and
demobilization
(
9
shifts
in
total).
The
actual
work
should
take
less
than
the
five
12­
hour
shifts
allowed.
3.
Good
weather
(
calm)
is
assumed
during
the
construction
works.
4.
All
components
fabricated
on
shore
and
transported
to
site
using
the
standard
supply
vessel.
No
allowance
has
been
made
for
the
transportation
of
modification
items
to
the
rig.
5.
The
installation
crew
will
scaffold
off
the
main
hull
to
create
a
construction
platform
at
the
sea
chest
opening.
6.
There
should
be
no
specific
preparation
for
the
shutdown
as
the
sea
chest
will
be
off
line
as
a
function
of
the
jacked
up
hull.
7.
Lifting
lugs
may
need
to
be
welded
to
the
hull
to
assist
with
the
manoeuvring
of
the
sea
chest
modification
components.
These
may
be
removed
on
completion
of
construction.

Capital
and
annual
O
&
M
costs
for
modification
of
existing
sea
chests
using
protruding
fine
mesh
screen
are
presented
in
Table
5.

Table
5.
Capital
and
O
&
M
Costs
for
Sea
Chest
Intake
Modification
Using
Protruding
Screen
for
Existing
Jackup
Facilities
Existing
Facility
Stainless
Steel
Fine
Mesh
Protruding
Screen
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
36,811
$
3,827
3000GPM
$
43,922
$
4,253
4500GPM
$
51,033
$
4,680
6000GPM
$
58,143
$
5,107
8500GPM
$
69,995
$
5,818
Existing
Facility
CuNi
Fine
Mesh
Protruding
Screen
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
37,278
$
3,855
3000GPM
$
44,855
$
4,309
4500GPM
$
52,433
$
4,764
6000GPM
$
60,011
$
5,219
8500GPM
$
72,640
$
5,976
March
12,
2004
­
Page
23
of
40
Description
of
Horizontal
Flow
Modifier
Retrofit
Modification:

Please
refer
to
Appendix
B
for
the
Horizontal
Flow
Modifier
drawings/
sketches.
A
detailed
cost
estimate
has
been
assembled
based
on
the
dimensions
calculated
for
a
4500GPM
(~
1000kl/
hr)
intake.
The
costs
for
other
intake
sizes
have
been
estimated
based
on
this
4500GPM
sea
chest
estimate.

The
horizontal
flow
modifier
option
is
divided
up
into
two
basic
configurations:
one
for
sea
chests
located
on
the
bottom
of
the
vessel
and
the
other
for
sea
chests
located
on
the
sidewalls
of
the
vessel.
The
arrangement
on
the
bottom
sea
chests
closely
resembles
a
standard
velocity
cap
arrangement.
A
plate
is
located
over
the
intake
opening
to
direct
the
flow
to
horizontal
between
the
plate
and
the
hull.
This
arrangement
will
be
suitable
for
hull
angles
up
to
30
°
off
horizontal
(
87%
of
velocity
will
still
be
horizontal).
For
hull
angles
greater
than
this
up
to
completely
vertical
the
side
sea
chest
arrangement
will
be
required.
This
design
includes
a
flow
diffuser
to
spread
the
flow
over
a
large
area
and
louvres
to
direct
the
flow
to
the
horizontal.
Both
of
these
designs
are
low
profile
to
reduce
any
fluid
dynamic
effects
on
the
hull.
The
existing
coarse
grill
over
the
sea
chest
will
be
retained.
It
is
intended
that
the
assembly
horizontal
flow
diverter
be
attached
using
hinges
to
the
hull
to
allow
easy
access
to
the
existing
intake
structure.

Proposed
Installation
Method:
1.
Personnel
to
undertake
the
works
will
be
flown
to
the
rig
on
the
standard
crew
change
helicopter
and
flown
back
to
shore
on
the
next
change
of
crew.
Two
helicopters
per
week
are
assumed
for
crew
change
 
one
every
3
days.
2.
Four
personnel
(
a
foreman,
a
welder
and
rigger)
will
be
required
to
undertake
the
work
and
will
be
at
the
rig
for
7
12­
hour
shifts
plus
2
additional
shifts
for
the
mobilization
and
demobilization
(
9
shifts
in
total).
The
actual
work
should
take
less
than
the
five
12­
hour
shifts
allowed.
3.
Good
weather
(
calm)
is
assumed
during
the
construction
works.
4.
All
components
fabricated
on
shore
and
transported
to
site
using
the
standard
supply
vessel.
No
allowance
has
been
made
for
the
transportation
of
modification
items
to
the
rig.
5.
The
installation
crew
will
scaffold
off
the
main
hull
to
create
a
construction
platform
at
the
sea
chest
opening.
6.
There
should
be
no
specific
preparation
for
the
shutdown
as
the
sea
chest
will
be
off
line
as
a
function
of
the
jacked
up
hull.

Capital
and
annual
O
&
M
costs
for
modification
of
existing
sea
chests
using
flow
modifier
are
presented
in
Table
6.

Table
6.
Capital
and
O
&
M
Costs
for
Sea
Chest
Intake
Modification
Using
Flow
Modifier
for
Existing
Jackup
Facilities
E
xisting
Facility
Bottom
Sea
Chest:
Horizontal
Flow
Diverter
Bottom
Sea
Chest
Flow
Rate:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
26,179
$
3,578
3000GPM
$
29,138
$
3,755
4500GPM
$
32,097
$
3,933
6000GPM
$
35,057
$
4,110
8500GPM
$
39,989
$
4,406
March
12,
2004
­
Page
24
of
40
Existing
Facility
Side
Sea
Chest:
Horizontal
Flow
Diverter
Side
Sea
Chest
Flow
Rate:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
24,912
$
3,664
3000GPM
$
29,303
$
3,927
4500GPM
$
33,695
$
4,191
6000GPM
$
38,087
$
4,454
8500GPM
$
45,406
$
4,893
2.
New
Facilities
New
facilities
have
the
advantage
that
they
have
unlimited
design
possibilities.
These
include
simply
designing
an
intake
opening
large
enough
to
allow
0.5ft/
sec
through
the
intake
with
either
a
fine
mesh
over
the
opening
or
a
flow
diverter
as
described
above.

For
the
purpose
of
estimating
the
cost
to
implement
these
technologies
on
new
facilities,
the
cost
to
install
the
proposed
retrofit
designs
above
in
a
shipyard
will
be
presented.
This
will
be
conservative
additional
cost
estimate
when
compared
with
existing
practices.
Since
the
installation
of
the
equipment
will
occur
during
the
construction
of
the
vessel,
only
the
additional
cost
of
the
set­
up
and
welding
will
be
included
(
ie.
no
scaffolding,
sand
blasting
or
other
preparations
will
be
included).

Capital
and
annual
O
&
M
costs
for
modification
of
sea
chest
intake
using
protruding
fine
mesh
screen
for
new
facilities
are
presented
in
Table
7.

Table
7.
Capital
and
O
&
M
Costs
for
Sea
Chest
Intake
Modification
Using
Protruding
Screen
for
New
Jackup
Facilities
New
Facility
Stainless
Steel
Fine
Mesh
Protruding
Screen
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
8,906
$
3,827
3000GPM
$
17,812
$
4,253
4500GPM
$
26,718
$
4,680
6000GPM
$
35,624
$
5,107
8500GPM
$
50,468
$
5,818
New
Facility
CuNi
Fine
Mesh
Protruding
Screen
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
9,373
$
3,855
3000GPM
$
18,746
$
4,309
4500GPM
$
28,119
$
4,764
6000GPM
$
37,491
$
5,219
8500GPM
$
53,113
$
5,976
Capital
and
annual
O
&
M
costs
for
modification
of
sea
chests
using
flow
modifier
for
new
facilities
are
presented
in
Table
8.
March
12,
2004
­
Page
25
of
40
Table
8.
Capital
and
O
&
M
Costs
for
Sea
Chest
Intake
Modification
Using
Flow
Modifier
for
New
Jackup
Facilities
New
Facility
Bottom
Sea
Chest:
Horizontal
Flow
Diverter
Bottom
Sea
Chest
Flow
Rate:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
3,574
$
3,578
3000GPM
$
7,147
$
3,755
4500GPM
$
10,721
$
3,933
6000GPM
$
14,294
$
4,110
8500GPM
$
20,250
$
4,406
New
Facility
Side
Sea
Chest:
Horizontal
Flow
Diverter
Side
Sea
Chest
Flow
Rate:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
4,987
$
3,664
3000GPM
$
9,974
$
3,927
4500GPM
$
14,961
$
4,191
6000GPM
$
19,948
$
4,454
8500GPM
$
28,259
$
4,893
March
12,
2004
­
Page
26
of
40
III.
Semi
Submersibles
and
Drill
Ships
A
number
of
semi
submersible
MODU
facilities
operate
in
the
OCS;
in
the
order
of
40
currently
operating
in
the
GOM
(
TDD
2001
6­
4).
These
facilities
typically
use
a
sea
chest
arrangement
to
draw
seawater
up
from
the
ocean
(
as
per
the
Tetratech
2003
Draft
Oil
and
gas
platform
CWIS
data).
March
12,
2004
­
Page
27
of
40
Drill
ships
may
be
purpose
designed
or
constructed
by
modifying
a
bulk
carrier.
These
facilities
typically
use
a
number
of
sea
chests
(
as
many
as
12)
to
draw
seawater
up
from
the
ocean
(
as
per
the
Tetratech
2003
Draft
Oil
and
gas
platform
CWIS
data).
March
12,
2004
­
Page
28
of
40
Modern
semi­
submersibles
and
drill
ships
use
a
technology
called
dynamic
positioning
to
achieve
a
steady
geographic
location
for
drilling.
A
series
of
direction
thrusters
(
see
diagram
above)
under
the
hull
of
the
vessel
are
controlled
by
on
board
global
positioning
equipment.
The
thrusters
generally
consume
a
significant
amount
of
power.
Consequently,
large
volumes
of
cooling
water
are
required
to
keep
the
generator
engines
cool.
It
would
be
reasonable
to
assume
that
the
thrusters
may
require
full
power
and
maximum
cooling
water
while
effectively
stationary.
This,
plus
the
cooling
water
that
is
required
for
normal
drilling
production
purposes
results
in
a
vessel
that
requires
a
great
deal
of
cooling
water.
Dynamically
positioned
drill
ships
typically
have
a
large
number
(
up
to
12)
of
sea
chests
or
sea
chests
with
very
high
flows
(
as
much
as
13MGPD).

Semi­
submersible
vessels
can
be
very
large
vessels
and
may
need
special
dry
dock
facilities
for
maintenance.
A
key
assumption
of
this
cost
module
is
that
the
vessel
is
already
in
dry
dock
for
other
work.

A.
Sea
Chest
Intake
Structures
Drill
ship
and
Semi
Submersible
MODUs
use
sea
chests
for
cooling
water
intake
structures.
There
are
a
number
of
different
generic
types
of
sea
chests
that
these
vessels
may
use.
There
are
single
pipe
sea
chests,
the
most
common
arrangement
for
commercial
vessels,
as
described
below:

Generic
Single
Pipe
Sea
Chest
Arrangement
in
the
Hull
Side
Wall
Pump
Header
External
Coarse
Screen
Screen
Box
with
removable
lid
Isolation
Valves
Vessel
Hull
Side
Wall
Fine
Screen
Inboard
Outboard
March
12,
2004
­
Page
29
of
40
Generic
Single
Pipe
Sea
Chest
Arrangement
in
the
Hull
Bottom
Since
MODUs
draw
large
quantities
of
cooling
water,
a
multiple
pipe
or
cavity
type
sea
chest
arrangement
is
also
common.
These
sea
chest
arrangements
incorporate
a
relatively
large
cavity
constructed
just
inside
the
vessel
hull.
This
cavity
may
have
one
or
more
openings
through
the
hull
into
the
open
ocean.
Seawater
passes
through
these
openings
and
floods
the
cavity.
A
number
of
pipes
may
draw
water
from
the
cavity
for
a
number
of
uses
around
the
vessel
(
including
cooling
water).
The
cavity
is
typically
sized
to
fit
between
the
primary
structural
supports
of
the
hull.
Enlargement
of
the
openings
into
the
ocean
is
limited
by
this
primary
hull
structure.
Following
is
a
diagram
describing
this
type
of
sea
chest
arrangement.

Elevation
of
Multiple
Pipe
Sea
Chest
Opening
through
Hull
Outboard
Looking
Inboard
Pump
Header
External
Coarse
Screen
Screen
Box
with
removable
lid
Isolation
Valves
Vessel
Bottom
Hull
Fine
Screen
Inboard
Outboard
Sea
Chest
Opening
with
Coarse
Mesh
Grille
Hull
Structure
A
A
Keel
Sea
Chest
cavity
between
vessel
structural
members
March
12,
2004
­
Page
30
of
40
Multiple
Pipe
Sea
Chest
Section
AA
Suitable
Technologies
for
Reducing
Impingement
and
Entrainment:

Technologies
that
would
be
suitable
for
use
on
these
types
of
intake
structures
include
the
fine
mesh
screen
and
velocity
cap
(
or
horizontal
flow
modifier)
technologies.
The
fine
mesh
screen
provides
a
physical
barrier
for
fish
whereas
the
velocity
cap
technology
utilises
the
behavioural
nature
of
fish
to
swim
against
a
horizontal
flow
(
minimise
entrainment).
Another
key
intention
is
to
limit
the
through
screen
velocity
to
0.5ft/
sec
or
less
so
that
it
is
low
enough
for
fish
to
swim
away
from
the
structure
(
minimise
impingement).
The
use
of
CuNi
alloys
and
air
sparging
is
a
suitable
technology
for
preventing
bio­
fouling
on
the
additional
equipment.

The
use
of
CuNi
alloys
is
a
suitable
technology
for
preventing
bio­
fouling
on
this
additional
equipment.
Air
sparging
will
be
ineffective
on
sea
chests
located
on
the
bottom
of
the
vessel
and
problematic
on
sidewall
sea
chests
(
due
to
air
entrainment
in
the
intake).
As
such,
the
air
sparging
technology
is
not
presented
for
these
intake
structure
modifications.

The
retrofit
structures
proposed
here
are
basically
added
on
to
the
existing
intake
structure.
In
order
to
reduce
the
intake
velocity
to
0.5
ft/
sec
or
less,
the
area
that
the
seawater
is
drawn
into
the
intake
has
to
be
a
minimum
size.
It
is
assumed
that
the
existing
structure
has
a
through
screen
velocity
greater
than
the
0.5ft/
sec
required
and
a
modification
is
required
to
increase
the
screen
area.

One
solution
may
include
cutting
large
holes
in
the
hull
to
increase
the
intake
size.
This
solution
is
not
presented
as
a
retrofit
option
for
existing
facilities
in
this
report
as
this
would
require
specific
vessel
drawings
to
define
the
modification.
However,
this
would
be
an
ideal
way
to
ensure
the
desired
through
screen
velocity
at
the
design
and
construction
phase.
Outboard
Inboard
Sea
Chest
Cavity
Hull
Hull
Structure
Multiple
pipes
draw
seawater
out
of
cavity
for
use
around
vessel
Sea
Chest
Opening
with
Coarse
Mesh
Grille
Seawater
flooding
cavity
March
12,
2004
­
Page
31
of
40
Possible
sea
chest
modifications
include
a
fine
mesh
screen
mounted
on
a
flow
diffuser
box
that
is
welded
to
the
hull.
Alternatively,
a
horizontal
flow
modifier
arrangement
may
be
used.
This
intake
arrangement
uses
the
velocity
cap
technology
to
achieve
horizontal
flow
into
the
intake.

It
must
be
noted
that
modification
of
this
type
of
facility
would
need
to
be
done
in
a
dry
dock.
Modifications
of
this
type
to
the
vessel
while
on
location
are
not
believed
to
be
possible.
The
construction
of
cofferdams
around
sections
of
the
hull
may
be
possible
in
some
situations
but
this
not
considered
a
practical
option
for
many
cases
(
such
as
sea
chests
under
the
hull).
Sub
sea
welding
onto
the
hull
has
not
been
considered
as
an
option
due
to
embrittlement
of
the
welds
and
possible
hull
damage.

Assumptions:
1.
The
vessel
is
in
dry
dock
for
other
work
such
as
routine
maintenance
overhaul.
2.
No
production
losses
or
dry
dock
fees
have
been
included
in
this
estimate.
3.
Inspection
intervals
for
fine
mesh
screens
and
horizontal
flow
modifiers
are
assumed
to
be
one
per
year.
This
has
been
based
on
typical
inspection
frequencies
for
onshore
and
coastal
facilities.
4.
It
is
assumed
that
the
inspection
of
existing
sea
chest
openings
is
annual.
The
inspection
and
maintenance
of
this
new
equipment
will
take
significantly
longer
than
current
practices.
An
allowance
of
an
additional
day
per
intake
has
been
included
for
divers
to
inspect
and
clean
the
new
intake
structures.
No
mobilization
or
demobilization
costs
are
included
as
this
estimate
is
for
the
incremental
facility
cost.
5.
6%
of
the
capital
cost
has
been
allowed
for
annual
parts
replacement
cost.

Cost
Estimate
for
Sea
Chest
Intakes
1.
Existing
Facilities
Description
of
Protruding
Fine
Mesh
Screen
Retrofit
Modification:

Please
refer
to
Appendix
A
for
the
Protruding
Fine
Mesh
Screen
Modification
drawings/
sketches.
A
detailed
cost
estimate
has
been
assembled
based
on
the
dimensions
calculated
for
a
4500GPM
(~
1000kl/
hr)
intake.
The
costs
for
other
intake
sizes
have
been
estimated
based
on
this
4500GPM
sea
chest
estimate.

The
protruding
fine
mesh
screen
option
is
a
low
profile
addition
welded
to
the
outside
of
the
hull
over
the
existing
intake
structure.
For
the
4500GPM
module,
the
addition
protrudes
approximately
5"
out
from
the
hull
and
includes
a
50"
by
100"
intake
screen
(
Item
2
Appendix
A).
An
even
flow
across
the
fine
mesh
screen
is
achieved
by
the
installation
of
a
flow
diffuser
inside
the
new
structure
between
the
existing
intake
and
the
screen
(
Item
3
Appendix
A).
Steel
bars
are
mounted
on
the
outside
of
the
fine
mesh
screen
to
protect
against
damage
(
Item
1
Appendix
A).
These
items
are
assembled
on
a
main
frame
that
is
welded
to
the
hull
of
the
vessel
(
Item
5
Appendix
A).

Capital
and
annual
O
&
M
costs
for
modification
of
existing
sea
chests
using
protruding
fine
mesh
screen
are
presented
in
Table
9.

Table
9.
Capital
and
O
&
M
Costs
for
Sea
Chest
Intake
Modification
Using
Protruding
Screen
for
Existing
Semi
Submersibles
and
Drill
Ships
March
12,
2004
­
Page
32
of
40
Existing
Facility
Stainless
Steel
Fine
Mesh
Protruding
Screen
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
9,693
$
2,123
3000GPM
$
19,387
$
2,550
4500GPM
$
29,080
$
2,976
6000GPM
$
38,773
$
3,403
8500GPM
$
54,928
$
4,114
Existing
Facility
CuNi
Fine
Mesh
Protruding
Screen
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
10,160
$
2,151
3000GPM
$
20,320
$
2,606
4500GPM
$
30,480
$
3,060
6000GPM
$
40,640
$
3,515
8500GPM
$
57,574
$
4,273
Description
of
Horizontal
Flow
Modifier
Retrofit
Modification:

Please
refer
to
Appendix
B
for
the
Horizontal
Flow
Modifier
drawings/
sketches.
A
detailed
cost
estimate
has
been
assembled
based
on
the
dimensions
calculated
for
a
4500GPM
(~
1000kl/
hr)
intake.
The
costs
for
other
intake
sizes
have
been
estimated
based
on
this
4500GPM
sea
chest
estimate.

The
horizontal
flow
modifier
option
is
divided
up
into
two
basic
configurations:
one
for
sea
chests
located
on
the
bottom
of
the
vessel
and
the
other
for
sea
chests
located
on
the
sidewalls
of
the
vessel.
The
arrangement
on
the
bottom
sea
chests
closely
resembles
a
standard
velocity
cap
arrangement.
A
plate
is
located
over
the
intake
opening
to
direct
the
flow
to
horizontal
between
the
plate
and
the
hull.
This
arrangement
will
be
suitable
for
hull
angles
up
to
30
°
off
horizontal
(
87%
of
velocity
will
still
be
horizontal).
For
hull
angles
greater
than
this
up
to
completely
vertical
the
side
sea
chest
arrangement
will
be
required.
This
design
includes
a
flow
diffuser
to
spread
the
flow
over
a
large
area
and
louvres
to
direct
the
flow
to
the
horizontal.
Both
of
these
designs
are
low
profile
to
reduce
any
fluid
dynamic
effects
on
the
hull.
The
existing
coarse
grill
over
the
sea
chest
will
be
retained.
It
is
intended
that
the
assembly
horizontal
flow
diverter
be
attached
using
hinges
to
the
hull
to
allow
easy
access
to
the
existing
intake
structure.
Capital
and
annual
O
&
M
costs
for
modification
of
existing
sea
chests
using
flow
modifier
are
presented
in
Table
10.

Table
10.
Capital
and
O
&
M
Costs
for
Sea
Chest
Intake
Modification
Using
Flow
Modifier
for
Existing
Semi
Submersibles
and
Drill
Ships
Existing
Facility
Bottom
Sea
Chest:
Horizontal
Flow
Diverter
Bottom
Sea
Chest
Flow
Rate:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
3,817
$
1,874
3000GPM
$
7,634
$
2,051
4500GPM
$
11,450
$
2,229
6000GPM
$
15,267
$
2,406
8500GPM
$
21,628
$
2,702
March
12,
2004
­
Page
33
of
40
Existing
Facility
Side
Sea
Chest:
Horizontal
Flow
Diverter
Side
Sea
Chest
Flow
Rate:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
5,249
$
1,960
3000GPM
$
10,499
$
2,223
4500GPM
$
15,748
$
2,487
6000GPM
$
20,997
$
2,750
8500GPM
$
29,746
$
3,189
2.
New
Facilities
New
facilities
have
the
advantage
that
they
have
unlimited
design
possibilities.
These
include
simply
designing
an
intake
opening
large
enough
to
allow
0.5ft/
sec
through
the
intake
with
either
a
fine
mesh
over
the
opening
or
a
flow
diverter
as
described
above.

For
the
purpose
of
estimating
the
cost
to
implement
these
technologies
on
new
facilities,
the
cost
to
install
the
proposed
retrofit
designs
above
in
a
shipyard
will
be
presented.
This
will
be
conservative
additional
cost
estimate
when
compared
with
existing
practices.
Since
the
installation
of
the
equipment
will
occur
during
the
construction
of
the
vessel,
only
the
additional
cost
of
the
set­
up
and
welding
will
be
included
(
ie.
no
scaffolding,
sand
blasting
or
other
preparations
will
be
included).

Capital
and
annual
O
&
M
costs
for
modification
of
sea
chests
using
protruding
fine
mesh
screen
for
new
facilities
are
presented
in
Table
11.

Table
11.
Capital
and
O
&
M
Costs
for
Sea
Chest
Intake
Modification
Using
Protruding
Screen
for
New
Semi
Submersibles
and
Drill
Ships
New
Facility
Stainless
Steel
Fine
Mesh
Protruding
Screen
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
8,906
$
2,123
3000GPM
$
17,812
$
2,550
4500GPM
$
26,718
$
2,976
6000GPM
$
35,624
$
3,403
8500GPM
$
50,468
$
4,114
New
Facility
CuNi
Fine
Mesh
Protruding
Screen
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
9,373
$
2,151
3000GPM
$
18,746
$
2,606
4500GPM
$
28,119
$
3,060
6000GPM
$
37,491
$
3,515
8500GPM
$
53,113
$
4,273
Capital
and
annual
O
&
M
costs
for
modification
of
sea
chests
using
flow
modifier
for
new
facilities
are
presented
in
Table
12.
March
12,
2004
­
Page
34
of
40
Table
12.
Capital
and
O
&
M
Costs
for
Sea
Chest
Intake
Modification
Using
Flow
Modifier
for
New
Semi
Submersibles
and
Drill
Ships
New
Facility
Bottom
Sea
Chest:
Horizontal
Flow
Diverter
Bottom
Sea
Chest
Flow
Rate:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
3,574
$
1,874
3000GPM
$
7,147
$
2,051
4500GPM
$
10,721
$
2,229
6000GPM
$
14,294
$
2,406
8500GPM
$
20,250
$
2,702
New
Facility
Side
Sea
Chest:
Horizontal
Flow
Diverter
Side
Sea
Chest
Flow
Rate:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
4,987
$
1,960
3000GPM
$
9,974
$
2,223
4500GPM
$
14,961
$
2,487
6000GPM
$
19,948
$
2,750
8500GPM
$
28,259
$
3,189
IV.
Submersibles
A
limited
number
of
submersible
MODU
facilities
operate
in
the
OCS;
in
the
order
of
6
are
currently
operating
in
the
GOM
(
TDD
2001
6­
4).
They
are
transported
to
various
sites
around
an
oil
field
to
undertake
exploration
and
development
drilling
activities.
When
they
arrive
at
the
desired
location,
they
fill
up
vast
ballast
tanks
with
seawater
for
stability
and
sink
to
the
ocean
floor
(
hence
the
name
submersible).

A.
Seawater
Intake
Structures
These
facilities
typically
use
a
combination
of
cooling
systems
that
include
radiators
and
sea
chest
arrangements
to
draw
seawater
up
from
the
ocean
(
as
per
the
Tetratech
2003
Draft
Oil
and
gas
platform
CWIS
data).
As
these
are
not
common
vessels,
details
on
the
cooling
water
arrangements
have
not
been
located.
It
is
assumed
that
the
sea
chest
arrangements
are
similar
to
drill
ships
and
semi
submersible
MODUs.
Furthermore,
it
is
possible
for
the
hull
of
these
vessels
to
be
concrete
structures.
This
may
significantly
alter
the
cost
of
the
retrofit
solution
verses
its
steel
counterpart.
It
is
assumed
for
this
cost
module
that
the
hull
is
made
from
steel.
March
12,
2004
­
Page
35
of
40
Suitable
Technologies
for
Reducing
Impingement
and
Entrainment:

As
it
has
been
assumed
that
the
sea
chests
for
these
vessels
are
similar
to
drill
ships
and
semi
submersibles,
the
suitable
technologies
described
above
also
apply
to
submersibles.

Assumptions:
1.
The
vessel
is
in
dry
dock
for
other
work
such
as
routine
maintenance
overhaul.
2.
No
production
losses
or
dry
dock
fees
have
been
included
in
this
estimate.
3.
The
sea
chest
arrangement
is
similar
to
those
found
on
drill
ships
and
semi
submersibles.
4.
The
hull
of
the
vessel
is
fabricated
using
steel.

Cost
Estimate
for
Sea
Chest
Intakes
1.
Existing
Facilities
Description
of
Protruding
Fine
Mesh
Screen
Retrofit
Modification:

Please
refer
to
Appendix
A
for
the
Protruding
Fine
Mesh
Screen
Modification
drawings/
sketches.
A
detailed
cost
estimate
has
been
assembled
based
on
the
dimensions
calculated
for
a
4500GPM
(~
1000kl/
hr)
intake.
The
costs
for
other
intake
sizes
have
been
estimated
based
on
this
4500GPM
sea
chest
estimate.

The
protruding
fine
mesh
screen
option
is
a
low
profile
addition
welded
to
the
outside
of
the
hull
over
the
existing
intake
structure.
For
the
4500GPM
module,
the
addition
protrudes
approximately
5"
out
from
the
hull
and
includes
a
50"
by
100"
intake
screen
(
Item
2
Appendix
A).
An
even
flow
across
the
fine
mesh
screen
is
achieved
by
the
installation
of
a
flow
diffuser
inside
the
new
structure
between
the
existing
intake
and
the
screen
(
Item
3
Appendix
A).
Steel
bars
are
mounted
on
the
outside
of
the
fine
mesh
screen
to
protect
against
damage
(
Item
1
Appendix
A).
These
items
are
assembled
on
a
main
frame
that
is
welded
to
the
hull
of
the
vessel
(
Item
5
Appendix
A).

Capital
and
annual
O
&
M
costs
for
modification
of
existing
sea
chests
using
protruding
fine
mesh
screen
are
presented
in
Table
13.

Table
13.
Capital
and
O
&
M
Costs
for
Sea
Chest
Intake
Modification
Using
Protruding
Screen
for
Existing
Submersibles
E
xisting
Facility
Stainless
Steel
Fine
Mesh
Protruding
Screen
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
9,693
$
2,123
3000GPM
$
19,387
$
2,550
4500GPM
$
29,080
$
2,976
6000GPM
$
38,773
$
3,403
8500GPM
$
54,928
$
4,114
Existing
Facility
CuNi
Fine
Mesh
Protruding
Screen
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
10,160
$
2,151
3000GPM
$
20,320
$
2,606
March
12,
2004
­
Page
36
of
40
4500GPM
$
30,480
$
3,060
6000GPM
$
40,640
$
3,515
8500GPM
$
57,574
$
4,273
Capital
and
annual
O
&
M
costs
for
modification
of
existing
sea
chests
using
flow
modifier
are
presented
in
Table
14.

Table
14.
Capital
and
O
&
M
Costs
for
Sea
Chest
Intake
Modification
Using
Flow
Modifier
for
Existing
Submersibles
Existing
Facility
Bottom
Sea
Chest:
Horizontal
Flow
Diverter
Bottom
Sea
Chest
Flow
Rate:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
3,817
$
1,874
3000GPM
$
7,634
$
2,051
4500GPM
$
11,450
$
2,229
6000GPM
$
15,267
$
2,406
8500GPM
$
21,628
$
2,702
Existing
Facility
Side
Sea
Chest:
Horizontal
Flow
Diverter
Side
Sea
Chest
Flow
Rate:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
5,249
$
1,960
3000GPM
$
10,499
$
2,223
4500GPM
$
15,748
$
2,487
6000GPM
$
20,997
$
2,750
8500GPM
$
29,746
$
3,189
2.
New
Facilities
New
facilities
have
the
advantage
that
they
have
unlimited
design
possibilities.
These
include
simply
designing
an
intake
opening
large
enough
to
allow
0.5ft/
sec
through
the
intake
with
either
a
fine
mesh
over
the
opening
or
a
flow
diverter
as
described
above.

For
the
purpose
of
estimating
the
cost
to
implement
these
technologies
on
new
facilities,
the
cost
to
install
the
proposed
retrofit
designs
above
in
a
shipyard
will
be
presented.
This
will
be
conservative
additional
cost
estimate
when
compared
with
existing
practices.
Since
the
installation
of
the
equipment
will
occur
during
the
construction
of
the
vessel,
only
the
additional
cost
of
the
set­
up
and
welding
will
be
included
(
ie.
no
scaffolding,
sand
blasting
or
other
preparations
will
be
included).

Capital
and
annual
O
&
M
costs
for
modification
of
sea
chests
using
protruding
fine
mesh
screen
for
new
facilities
are
presented
in
Table
15.

Table
15.
Capital
and
O
&
M
Costs
for
Sea
Chest
Intake
Modification
Using
Protruding
Screen
for
New
Submersibles
New
Facility
Stainless
Steel
Fine
Mesh
Protruding
Screen
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
8,906
$
2,123
3000GPM
$
17,812
$
2,550
March
12,
2004
­
Page
37
of
40
4500GPM
$
26,718
$
2,976
6000GPM
$
35,624
$
3,403
8500GPM
$
50,468
$
4,114
New
Facility
CuNi
Fine
Mesh
Protruding
Screen
Fine
Mesh
Screen:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
9,373
$
2,151
3000GPM
$
18,746
$
2,606
4500GPM
$
28,119
$
3,060
6000GPM
$
37,491
$
3,515
8500GPM
$
53,113
$
4,273
Capital
and
annual
O
&
M
costs
for
modification
of
sea
chests
using
flow
modifier
for
new
facilities
are
presented
in
Table
16.

Table
16.
Capital
and
O
&
M
Costs
for
Sea
Chest
Intake
Modification
Using
Flow
Modifier
for
New
Submersibles
New
Facility
Bottom
Sea
Chest:
Horizontal
Flow
Diverter
Bottom
Sea
Chest
Flow
Rate:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
3,574
$
1,874
3000GPM
$
7,147
$
2,051
4500GPM
$
10,721
$
2,229
6000GPM
$
14,294
$
2,406
8500GPM
$
20,250
$
2,702
New
Facility
Side
Sea
Chest:
Horizontal
Flow
Diverter
Side
Sea
Chest
Flow
Rate:
Initial
Capital
Cost
per
Structure
Annual
Maintenance
Cost
per
Structure
1500GPM
$
4,987
$
1,960
3000GPM
$
9,974
$
2,223
4500GPM
$
14,961
$
2,487
6000GPM
$
19,948
$
2,750
8500GPM
$
28,259
$
3,189
V.
Drill
Barges
Image
from
Flexifloat
web
page
A
number
of
drill
barge
MODU
facilities
operate
in
the
OCS;
in
the
order
of
20
currently
operating
in
the
GOM
(
TDD
2001
6­
4).
March
12,
2004
­
Page
38
of
40
There
is
no
limit
to
number
of
different
possible
designs
of
these
facilities.
Furthermore,
no
group
of
suppliers
that
specialise
in
this
type
of
equipment
has
been
identified.
As
such,
drill
barges
may
vary
vastly
in
fundamental
design
and
layout.
They
are
transported
(
generally
towed
but
self­
propelled
would
be
possible)
to
various
sites
around
an
oil
field
to
undertake
exploration
and
development
drilling
activities.

A.
Seawater
Intake
Structures
EPA
data
gathered
on
3
drill
barges.
These
vessels
all
utilise
"
simple
pipe"
seawater
intakes.
Since
these
vessels
are
predominantly
shallow
water
and
costal/
estuarine,
the
intake
is
assumed
to
be
very
shallow
and
easily
retractable
(
to
get
across
sandbars
etc).
As
such
a
single
cost
module
for
both
new
and
existing
facilities
has
been
presented.

Cost
Estimates
for
Sea
Water
Intakes
1.
New
and
Existing
Facilities
For
new
facilities,
there
is
no
special
detail
required
for
the
estimate
to
fit
this
new
equipment.
However,
a
brief
description
of
what
has
been
allowed
for
is
warranted:
1.
Fine
Mesh
Screens
and
Velocity
Caps:
In
addition
to
the
purchase
cost
of
the
screen
or
cap,
the
estimate
has
allowed
for
an
ANSI
class
150#
flange
to
be
welded
to
the
intake
pipe.
A
bolt
up
of
the
flanged
connection
has
also
been
calculated.
This
work
would
be
undertaken
in
a
fabrication
yard
during
the
construction
process
of
the
platform.

Operation
and
maintenance
costs:
1.
Onboard
personnel
will
carry
out
all
operation,
inspection
and
maintenance
work.
The
cost
estimate
has
been
based
on
$
60/
hr
MODU
labour
rates.
One
day
per
year
(
8
hours)
has
been
allowed
for
inspection
and
cleaning
of
the
intake
screen.
2.
Operation
costs
of
the
system
include
the
supply
of
power
to
the
air
sparging
system
for
normal
operation.
The
frequency
of
air
sparge
operation
is
dependant
on
the
quantity
of
debris
in
the
water.
This
frequency
ranges
from
once
per
week
to
once
an
hour.
Since
the
vessel
is
mobile
and
all
types
of
water
may
be
encountered,
it
is
assumed
that
the
air
sparge
system
is
automatically
operated
every
hour
(
24
times
a
day).
Furthermore,
it
is
assumed
that
the
accumulator
takes
0.5
hours
to
re­
charge
after
an
air
burst
event.
3.
Based
on
vendor
information,
routine
inspection
and
maintenance
requirements
for
the
air
sparging
system
have
been
estimated
based
on
3
hours
per
week
for
all
system
sizes.
4.
Inspection
intervals
for
fine
mesh
screens
and
horizontal
flow
modifiers
are
assumed
to
be
one
per
year.
This
has
been
based
on
typical
inspection
frequencies
for
onshore
and
coastal
facilities.
5.
6%
of
the
capital
cost
has
been
allowed
for
annual
parts
replacement
cost.

Tables
17
and
18
present
the
capital
and
O
&
M
cost
estimates
for
new
and
existing
facility
intake
modification
using
fine
mesh
screens
and
velocity
caps,
respectively.
March
12,
2004
­
Page
39
of
40
Table
17.
Cost
Estimates
for
New
and
Existing
Simple
Pipe
Intake
Modification
for
Drill
Barges
Using
Fine
Mesh
Screens
Stainless
Steel
Fine
Mesh
Screens:
No
Additional
Anti­
Fouling
Fine
Mesh
Screen:
Cost
Per
Intake
O&
M
Per
Intake
12"
Intake
Pipe
$
3,926
$
672
18"
Intake
Pipe
$
5,934
$
762
24"
Intake
Pipe
$
7,563
$
834
30"
Intake
Pipe
$
10,140
$
954
36"
Intake
Pipe
$
13,633
$
1,135
Stainless
Steel
Fine
Mesh
Screens:
Air
Sparge
Anti­
Fouling
Fine
Mesh
Screen:
Cost
Per
Intake
O&
M
Per
Intake
12"
Intake
Pipe
$
20,626
$
11,295
18"
Intake
Pipe
$
23,434
$
11,433
24"
Intake
Pipe
$
30,313
$
11,820
30"
Intake
Pipe
$
34,940
$
12,455
36"
Intake
Pipe
$
42,133
$
12,858
CuNi
Fine
Mesh
Screens:
No
Additional
Anti­
Fouling
Fine
Mesh
Screen:
Cost
Per
Intake
O&
M
Per
Intake
12"
Intake
Pipe
$
6,016
$
797
18"
Intake
Pipe
$
9,034
$
948
24"
Intake
Pipe
$
13,063
$
1,164
30"
Intake
Pipe
$
18,840
$
1,476
36"
Intake
Pipe
$
26,473
$
1,906
CuNi
Fine
Mesh
Screens:
Air
Sparge
Anti­
Fouling
Fine
Mesh
Screen:
Cost
Per
Intake
O&
M
Per
Intake
12"
Intake
Pipe
$
22,716
$
11,421
18"
Intake
Pipe
$
26,534
$
11,619
24"
Intake
Pipe
$
35,813
$
12,150
30"
Intake
Pipe
$
43,640
$
12,977
36"
Intake
Pipe
$
54,973
$
13,629
March
12,
2004
­
Page
40
of
40
Table
18.
Cost
Estimates
for
New
and
Existing
Simple
Pipe
Intake
Modifications
for
Drill
Barges
Using
Velocity
Caps
Velocity
Caps:
Stainless
Steel
Velocity
Cap:
Cost
Per
Intake
O&
M
Per
Intake
12"
Intake
Pipe
$
25,726
$
1,980
18"
Intake
Pipe
$
26,234
$
1,980
24"
Intake
Pipe
$
27,663
$
2,040
30"
Intake
Pipe
$
29,740
$
2,130
36"
Intake
Pipe
$
32,713
$
2,280
Velocity
Caps:
CuNi
Anti­
Fouling
Velocity
Cap:
Cost
Per
Intake
O&
M
Per
Intake
12"
Intake
Pipe
$
25,726
$
1,980
18"
Intake
Pipe
$
26,234
$
1,980
24"
Intake
Pipe
$
27,663
$
2,040
30"
Intake
Pipe
$
29,740
$
2,130
36"
Intake
Pipe
$
32,713
$
2,280