UNITED
STATES
ENVIRONMENTAL
PROTECTION
AGENCY
WASHINGTON,
D.
C.

Engineering
and
Analysis
Division
Office
of
Science
and
Technology
Office
of
Water
MEMORANDUM
SUBJECT:
Site
Visit:
for
EPRI
Grant/
Alden
Laboratory,
MA
CWIS
Technologies
Workshop,
March
26­
27,
2002
FROM:
Dana
Thomas
TO:
W­
00­
32
Docket
On
26
­
27
March
2002,
I
attended
the
CWIS
(
Cooling
Water
Intake
Structure)
Technologies
Workshop:
EPRI
Research
on
Cylindrical
Wedgewire
Screens
and
Artificial
Fish
Barriers
at
the
Alden
Research
Laboratory
in
Holden,
MA.
The
conference
was
part
of
the
grant
workplan
and
included
a
tour
of
the
test
facilities
for
wedgewire
screens
and
artificial
barriers.

Conference
notes:
Presentations
of
research
funded
in
part
by
EPA
grant
#
829108010
Day
One
~
March
26th:

Wedgewire
screen
studies:
Used
surrogate
eggs
(
flavor
beads)
to
mimic
Striped
bass
eggs
(
4.5
mm;
largest
of
all
species
tested).
Striped
bass
larvae
are
typically
4
­
9
mm.
Conditions
tested
were
0.5
mm,
1.0
mm
and
2.0
mm
wedgewire
screens
with
0.5
or
1.0
ft/
sec
through
flow
velocity
and
a
0

or
90

orientation
of
screen
to
flow.

Fouling
on
outside
of
screen
is
not
such
a
problem;
divers
can
clean
it
off
and
air
backwashing
is
effective
for
debris.
A
wedgewire
screen
can
be
heavily
fouled
(
as
in
Delaware
Bay)
and
still
pull
design
capacity.
Eggs
can
be
damaged
(
abrasion)
when
rolling
along
the
screen
although
they
are
not
impinged
or
entrained.

Highest
egg
entrainment
occurred
at
2.0
mm
screen,
0.5
ft/
sec
slot
velocity
and
90

orientation.
Highest
larvae
entrainment
occurred
at
2.0
mm
screen,
0.5
ft/
sec
slot
velocity
and
90

orientation.

Less
impingement
as
channel
velocity
increases
to
1.0
ft/
sec.
At
higher
slot
velocities,
1
ft/
sec,
larvae
are
unable
to
un­
impinge
from
the
screen.
Regarding
entrainment
survival,
Ned
Taft
of
Alden
stated
"
It's
safe
to
say
with
the
little
guys
that
they
are
dead."

Video
demonstrations:
They
will
send
a
CD­
rom
with
the
video
demonstrations
(
will
be
included
in
docket
when
received
by
EPA).

With
0.5
mm
screen:
Eggs
had
a
tendency
to
impinge
at
the
back
of
screen
with
0

orientation,
even
with
lowest
channel
velocity
of
0.25
ft/
sec.
At
1
ft/
sec
channel
velocity,
eggs
moved
over
the
screen
with
no
impingement.

With
1.0
mm
screen:
more
impingement
at
0.25
ft/
sec.

With
2.0
mm
screen:
impingement
at
back
of
screen
with
0.25
ft/
sec;
no
impingement
at
1.0
ft/
sec.

Larvae
tests:
With
1.0
mm
screen,
1.0
ft/
sec
through
flow
and
0.25
ft/
sec
channel
velocity,
the
larvae
could
swim
around
the
screen
and
were
not
impinged.

Regarding
MGD
pull
and
screen
size:
Mark
Watson
of
Johnson
Screens
is
a
good
contact.
Flow
through
depends
on
slot
size;
can
reach
800
gallons
per
minute.

Doug
Dixon
of
EPRI:
the
earliest
lifestages
will
have
the
hardest
time
to
get
off;
they
need
some
swimming
ability.

Artificial
Barrier
(
Gunderboom)
presentation:
can
have
perforations
0.5
to
1.5
mm;
flow
=
10
GPM/
ft2.
Uses
air
bursts
to
prevent
biofouling.

Ed
Radle
(
NYSDEC):
at
0.01
ft/
sec
(
5
GPM/
ft2),
American
shad
(
day
old)
had
no
problem
swimming
to
avoid
impingement.
Critiqued
Pisces
study
of
Gunderboom
efficacy:
algae
on
boom
did
not
affect
filtering
ability;
the
Pisces
test
did
not
use
air
sparging.

Day
2
~
March
27th:

Louver/
Bar
Rack
Studies:
observed
video
demonstrations;
should
be
included
with
CD­
Rom.

Ned
Taft
(
Alden):
It
is
possible
to
install
at
0.5
mm
mesh
overlay
(
nylon
or
polypropylene)
on
a
conventional
(
metal)
3/
8"
screen;
may
have
weight
problems
adding
wedgewire
screens
to
traveling
screens.
