­
1­
316b
Phase
II
Cost
Module
3.0
Existing
Submerged
Offshore
Intakes
­
Add
Velocity
Caps
Velocity
caps
are
applicable
to
submerged
offshore
intakes.
Adding
velocity
caps
to
facilities
with
existing
or
new
submerged
offshore
intakes
only
provides
impingement
reduction.
Therefore,
this
module
may
be
most
applicable
when
the
compliance
option
only
requires
impingement
controls
and
the
intake
requires
upgrading.
However
depending
on
site­
specific
conditions,
velocity
caps
could
conceivably
be
used
in
conjunction
with
onshore
screening
systems
tailored
for
entrainment
improvement.

Research
on
velocity
cap
vendors
identified
only
one
vendor
located
in
Canada.
(
A
possible
reason
for
this
scarcity
in
vendors
is
that
many
velocity
caps
are
designed
and
fabricated
on
a
site­
specific
basis.)
This
vendor
manufactures
a
velocity
cap
called
the
"
Invisihead,"
and
was
contacted
for
cost
information
(
Elarbash
2002a
and
2002b).
The
Invisihead
is
designed
with
a
final
entrance
velocity
of
0.3
fps
and
has
a
curved
cross­
section
that
gradually
increases
the
velocity
as
water
is
drawn
farther
into
the
head.
The
manufacturer
states
the
gradual
increase
in
velocity
though
the
velocity
cap
minimizes
entrainment
of
sediment
and
suspended
matter
and
minimizes
inlet
pressure
losses
(
Elmosa
2002).
All
costs
presented
below
are
in
July
2002
dollars.

Capital
Costs
The
vendor
provided
information
for
estimating
retrofit
costs
for
velocity
caps
manufactured
both
from
carbon
steel
and
from
stainless
steel.
Stainless
steel
construction
is
recommended
for
saltwater
conditions
to
minimize
corrosion.
Carbon
steel
is
recommended
for
freshwater
systems.
Due
to
the
rather
large
opening,
Invisihead
performance
is
not
affected
by
the
attachment
of
Zebra
mussels,
so
no
special
materials
of
construction
are
required
where
Zebra
mussels
are
present.

Installation
costs
include
the
cost
for
a
support
vessel
and
divers
to
cut,
weld
and/
or
bolt
the
fitting
flange
for
the
velocity
cap;
make
any
needed
minor
reinforcements
of
the
existing
intake;
and
install
the
cap
itself.
Installation
was
said
to
take
between
two
and
seven
days,
depending
on
the
size
and
number
of
heads
in
addition
to
the
retrofit
steps
listed
above.
Costs
also
include
mobilization
and
demobilization
of
the
installation
personnel,
barge,
and
crane.
The
vendor
indicated
these
costs
included
engineering
and
contractor
overhead
and
profit,
but
did
not
provide
break­
outs
or
percentages
for
these
cost
components.
The
estimated
capital
costs
do
not
yet
include
contingency
costs,
which
will
be
incorporated
separately.
EPA
has
concluded
that
the
installation
costs
for
adding
a
velocity
cap
on
a
new
intake
(
relocated
offshore)
and
on
an
existing
offshore
intake
should
be
similar
because
most
of
the
costs
involve
similar
personnel
and
equipment.
(
See
the
"
Application"
section
below
for
a
discussion
of
new/
existing
submerged
offshore
intake
cost
components.)

Table
3­
1
presents
the
component
(
material,
installation,
and
mobilization/
demobilization)
and
total
capital
costs
for
stainless
steel
and
carbon
steel
velocity
caps
provided
by
the
vendor
(
Elarbash
2002a
and
2002b)
.
Data
are
presented
for
flows
ranging
from
5,000
gpm
to
350,000
gpm.
Figure
3­
1
presents
a
plot
of
these
data.
The
upper
end
of
this
flow
range
covers
existing
submerged
pipes
up
­
2­
to
15
feet
in
diameter
at
pipe
velocities
of
approximately
5
fps.
Second­
order
polynomial
equations
provided
the
best
fit
to
the
data
and
were
used
to
produce
cost
curves.
These
cost
curves
serve
as
the
basis
for
estimating
capital
costs
for
installing
velocity
caps
on
existing
or
new
intakes
submerged
offshore
at
Phase
II
facilities.
When
applying
these
cost
curves,
if
the
intake
flow
exceeds
350,000
gpm
plus
10%
(
385,000
gpm),
the
flow
is
divided
into
equal
increments
and
these
lower
flows
costed.
The
costs
for
these
individual
incremental
flows
are
summed
to
estimate
total
capital
cost.
In
these
cases,
costs
are
assumed
to
be
applied
to
multiple
intake
pipes.
If
the
intake
flow
is
less
than
5,000
gpm,
the
capital
cost
for
5,000
gpm
will
be
used
rather
than
extrapolating
beyond
the
bottom
end
of
the
cost
curve.

O&
M
Costs
For
velocity
caps,
O&
M
costs
generally
include
routine
inspection
and
cleaning
of
the
intake
head.
As
noted
above,
biofouling
does
not
affect
velocity
cap
performance,
so
rigorous
cleaning
is
not
necessary.
The
vendor
stated
that
their
equipment
is
relatively
maintenance
free.
However,
O&
M
costs
based
on
an
annual
inspection
and
cleaning
of
offshore
intakes
by
divers
were
cited
by
facilities
with
existing
offshore
intakes,
including
some
with
velocity
caps
and
especially
those
with
bar
racks
at
the
intake.
Therefore,
estimated
O&
M
costs
are
presented
for
an
annual
inspection
and
cleaning
by
divers
because
EPA
believes
this
is
common
practice
for
submerged
offshore
intakes
of
all
types.

Table
3­
2
presents
the
component
and
total
O&
M
costs
for
the
diver
inspection
and
cleaning,
for
one
to
four
days
(
Paroby
1999).
In
general,
O&
M
costs
are
based
on
less
than
one
day
per
head
for
inspection
and
cleaning
of
smaller
intake
heads
and
one
day
per
head
for
the
largest
intake
head.
There
is
a
minimum
of
one
day
for
each
inspection
event.
Inspection
and
cleaning
events
are
assumed
to
occur
once
per
year.
Figure
3­
2
presents
the
plot
of
the
O&
M
costs
by
flow.
A
second­
order
polynomial
equation
provided
the
best
fit
to
this
data
and
serves
as
the
basis
for
estimating
the
O&
M
costs.

Figure
3­
2
also
shows
data
for
two
facilities
that
reported
actual
O&
M
costs
based
on
diver
inspection
and
cleaning
of
submerged
offshore
intakes.
While
these
two
facilities
use
different
intake
technologies
(
passive
screens
for
the
smaller
flow
and
bar
rack
type
intakes
for
the
larger
flow),
the
inspection
and
cleaning
effort
should
be
similar
for
all
three
types
of
intakes.
For
both
facilities,
the
actual
reported
O&
M
costs
were
less
than
the
costs
estimated
using
the
cost
curves,
indicating
that
the
estimated
O&
M
costs
should
be
considered
as
high­
side
estimates.
­
3­
Application
As
Retrofit
of
Existing
Offshore
Intake
Adding
velocity
caps
to
facilities
with
existing
offshore
intakes
will
provide
impingement
reduction
only.
For
facilities
withdrawing
from
saltwater/
brackish
waters
(
ocean
and
estuarine/
tidal
rivers),
the
capital
cost
curve
for
stainless
steel
caps
will
be
applied.
For
the
remaining
facilities
withdrawing
freshwater
(
freshwater
rivers/
streams,
reservoirs/
lakes,
Great
Lakes),
the
capital
cost
curve
for
carbon
steel
caps
will
be
applied.
The
same
O&
M
cost
curve
will
be
used
for
both
freshwater
and
saltwater
systems.
It
is
assumed
that
the
existing
intake
is
in
a
location
that
will
provide
sufficient
clearance
and
is
away
from
damaging
wave
action.

As
Component
of
Relocating
Existing
Shoreline
Intake
to
Submerged
Offshore
These
same
velocity
cap
retrofit
costs
can
be
incorporated
into
retrofits
where
an
existing
shoreline
intake
is
relocated
to
submerged
offshore.
In
this
application,
some
of
the
same
equipment
and
personnel
used
in
velocity
cap
installation
may
also
be
used
to
install
other
intake
components,
such
as
the
pipe.
Therefore,
the
mobilization/
demobilization
component
could
be
reduced
if
these
tasks
are
determined
to
occur
close
together
in
time.
However,
a
high­
side
costing
approach
would
be
to
cost
each
step
separately,
using
the
same
velocity
cap
costs
for
both
new
and
existing
offshore
intake
pipes.
In
this
case,
the
installation
costs
for
velocity
caps
at
existing
offshore
intakes
(
which
include
costs
for
cutting,
and
welding
and/
or
bolting
the
velocity
cap
in
place)
are
assumed
to
also
cover
costs
of
installing
connection
flanges
at
new
offshore
intakes.
Costs
for
other
components
of
relocating
existing
shoreline
intakes
to
submerged
offshore
are
developed
as
a
separate
cost
module
associated
with
passive
screens.
The
compliance
cost
estimates
did
not
include
this
scenario.

References
Elarbash,
M.
Elmosa
Canada.
email
correspondence
with
John
Sunda,
SAIC
concerning
cost
and
technical
data
for
Invisihead
velocity
caps.
August
9,
2002a
Elarbash,
M.
Elmosa
Canada.
email
correspondence
with
John
Sunda,
SAIC
concerning
cost
and
technical
data
for
Invisihead
velocity
caps.
August
19,
2002b
Elmosa.
Website
at
http://
www.
imasar.
com/
elmosa/
invisiheaddetails.
htm
accessed
May
9,
2002.

Paroby,
Rich.
Personal
communication
between
Rich
Paroby,
District
Sales
Manager,
Water
Process
Group
and
Deborah
Nagle,
USEPA
E­
mail
dated
May
12,
1999.
­
4­

Item
Daily
Cost*
One
Time
Cost*
Total
Duration
One
Day
One
Day
Two
Day
Three
Day
Four
Day
Cost
Year
1999
2002
2002
2002
2002
Supervisor
$
575
$
575
$
627
$
1,254
$
1,880
$
2,507
Tender
$
200
$
200
$
218
$
436
$
654
$
872
Diver
$
375
$
750
$
818
$
1,635
$
2,453
$
3,270
Air
Packs
$
100
$
100
$
109
$
218
$
327
$
436
Boat
$
200
$
200
$
218
$
436
$
654
$
872
Mob/
Demob
$
3,000
$
3,000
$
3,270
$
3,270
$
3,270
$
3,270
Total
$
4,825
$
5,260
$
7,250
$
9,240
$
11,230
*
Source:
Paroby
1999
(
cost
adjusted
to
2002
dollars).

Installation
and
Maintenance
Diver
Team
Costs
Adjusted
Total
Flow
(
gpm)
#
Heads
Material
Costs
­
Stainless
Steel
/
Head
Material
Costs
­
Stainless
Steel
Total
Material
Costs
­
Carbon
Steel
/
Head
Material
Costs
­
Carbon
Steel
Total
Installation
Mobilization/
Demobilization
Total
Capital
Costs
­
Stainless
Steel
Total
Capital
Costs
­
Carbon
Steel
Total
O&
M
Water
Type
All
Saltwater
Saltwater
Freshwater
Freshwater
All
All
Saltwater
Freshwater
All
5,000
1
$
30,000
$
30,000
$
22,500
$
22,500
$
25,000
$
10,000
$
65,000
$
57,500
$
5,260
10,000
1
$
30,000
$
30,000
$
22,500
$
22,500
$
30,000
$
15,000
$
75,000
$
67,500
$
5,260
25,000
1
$
40,000
$
40,000
$
30,000
$
30,000
$
35,000
$
15,000
$
90,000
$
80,000
$
5,260
50,000
2
$
35,000
$
70,000
$
26,250
$
52,500
$
49,000
$
25,000
$
144,000
$
126,500
$
7,250
100,000
2
$
80,000
$
160,000
$
60,000
$
120,000
$
49,000
$
25,000
$
234,000
$
194,000
$
7,250
200,000
4
$
80,000
$
320,000
$
60,000
$
240,000
$
98,000
$
30,000
$
448,000
$
368,000
$
9,240
350,000
4
$
106,000
$
424,000
$
79,500
$
318,000
$
98,000
$
30,000
$
552,000
$
446,000
$
11,230
Note:
Vendor
indicated
installation
took
2
to
7
days
Note:
Installation
includes
retrofit
activities
such
as
cutting
pipe
and
&
attaching
connection
flange
on
intake
inlet
pipe.

Velocity
Cap
Retrofit
Capital
and
O&
M
Costs
(
2002
$)

Table
3­
1
Table
3­
2
­
5­

Velocity
Cap
Capital
Costs
2002
Dollars
y
=
­
3E­
06x
2
+
2.4809x
+
38934
R
2
=
0.9917
y
=
­
2E­
06x
2
+
2.0196x
+
38053
R
2
=
0.9913
$
0
$
50,000
$
100,000
$
150,000
$
200,000
$
250,000
$
300,000
$
350,000
$
400,000
$
450,000
$
500,000
$
550,000
$
600,000
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
Flow
(
gpm)

Capital
Cost
($)
Stainless
Steel
Carbon
Steel
Figure
3­
1
­
6­

Velocity
Cap
O&
M
Cost
2002
Dollars
y
=
­
3E­
08x
2
+
0.0262x
+
5113
R
2
=
0.9649
$
0
$
2,000
$
4,000
$
6,000
$
8,000
$
10,000
$
12,000
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
Flow
(
gpm)

Annual
O&

M
Cost
($)
Velociity
Cap
O&
M
Actual
Diver
Based
O&
M
Figure
3­
2
