MEMO
To:
Phase
III
Record
From:
Ron
Rimelman
and
Kelly
Meadows,
Tetra
Tech
Date:
June
2,
2004
RE:
Potential
Additional
Pre­
approved
Technologies
for
Phase
III
Facilities
In
the
final
Phase
II
regulations,
EPA
identified
submerged
cylindrical
wedge­
wire
screens
as
an
Approved
Design
and
Construction
Technology.
On
May
12th,
Tetra
Tech
316(
b)
staff
participated
in
a
conference
call
with
Martha
Segall
to
discuss
additional
intake
technologies
that
could
potentially
be
incorporated
into
the
Phase
III
regulations
as
pre­
approved
technologies.
This
memo
serves
as
a
summary
of
those
discussions.

In
summary,
two
additional
technologies
were
identified
that
could
be
able
to
regularly
meet
the
performance
standards
under
the
appropriate
conditions.

Submerged
offshore
intake
structures
It
was
noted
that
a
properly
sited
offshore
submerged
intake
structure
can
eliminate
virtually
all
entrainment,
as
the
intake
can
be
located
outside
of
sensitive
portions
of
the
waterbody.
An
example
is
San
Onofre
Nuclear
Generating
Station
(
SONGS),
where
the
intake
is
located
approximately
1/
4
mile
offshore.

This
technology
does
pose
two
significant
problems
for
implementation:
1)
converting
a
facility
to
an
offshore
intake
is
likely
to
be
extremely
expensive
and
time­
consuming
and
2)
how
would
a
facility
select
an
appropriate
location
for
the
offshore
intake
without
performing
additional
studies
at
those
offshore
locations?

Another
issue
to
consider
for
selecting
a
submerged
offshore
intake
is
whether
the
intake
technology
is
required
to
address
impingement
and/
or
entrainment
concerns.
For
example,
a
properly
located
intake
that
has
no
other
intake
technologies
(
i.
e.,
a
simple
pipe)
could
meet
the
entrainment
requirements.
However,
by
adding
a
velocity
cap
to
the
intake,
the
technology
may
also
be
able
to
address
impingement
requirements.

In
the
industry
survey,
204
Phase
III
facilities
(
weighted
data)
responded
as
having
a
submerged
offshore
intake
(
out
of
a
weighted
universe
of
651
facilities).
It
is
interesting
to
note
that
only
19
of
these
facilities
(
weighted
data)
were
located
on
tidal
rivers
or
an
ocean,
but
similar
logic
can
be
applied
to
both
marine
and
freshwater
intakes.
Regardless
of
waterbody
type,
a
properly
located
submerged
offshore
intake
could
meet
the
entrainment
requirements,
and,
when
combined
with
a
velocity
cap,
may
also
meet
the
impingement
requirements.
Barrier
nets/
aquatic
filter
barriers
Barrier
nets
can
be
very
effective
at
reducing
impingement.
Aquatic
filter
barrier
systems,
such
as
Gunderboom,
are
also
reasonably
effective
at
meeting
impingement
and
entrainment
standards.

These
technologies
also
pose
implementation
problems
at
some
facilities:
1)
these
technologies
are
not
feasible
for
some
facilities,
especially
those
in
waterbodies
with
high
debris
loading
or
vessel
traffic
and
2)
these
technologies
often
require
a
substantial
amount
of
modification
and
follow­
up
by
the
facility
to
operate.
However,
given
that
these
technologies
would
be
integral
to
the
functioning
of
the
intake
and
the
facility,
optimizing
their
performance
would
be
in
the
facility's
best
interests,
thereby
possibly
reducing
the
need
for
additional
monitoring
or
permitting
requirements.

In
the
industry
survey,
only
six
Phase
III
facilities
(
weighted
data)
responded
as
having
a
fish
net
barrier
(
out
of
a
weighted
universe
of
651
facilities).
Despite
the
seemingly
low
number
of
facilities
employing
this
type
of
technology,
two
factors
may
make
this
technology
more
attractive:
1)
the
survey
data
is
from
1998
and
more
facilities
may
have
implemented
this
technology
since
that
time
and
2)
these
technologies
(
especially
barrier
nets)
can
be
inexpensive
to
install
and
the
installation
often
does
not
affect
facility
operations.

Other
considerations
Two
other
technologies
were
also
discussed
and
it
was
decided
that
these
were
likely
not
appropriate
technologies
to
consider
for
pre­
approved
technologies.
Modified
traveling
screens
and
variable
speed
pumps
have
shown
measurable
results
in
reducing
impingement
and
entrainment,
but
are
unlikely
to
meet
the
performance
standards
on
a
consistent
basis.
Generally,
these
technologies
require
a
certain
level
of
adaptive
management
and
modification
to
optimize
the
performance,
which
inherently
defeats
the
purpose
of
selecting
technologies
with
a
reduced
burden
to
the
facility.

It
was
also
noted
that
there
may
be
policy/
legal
conflicts
in
approving
any
additional
technologies,
as
this
could
be
seen
as
contradictory
to
the
pre­
approved
technology
option
in
the
Phase
II
regulations.
However,
it
was
suggested
that
any
additional
technologies
could
be
conditionally
approved
for
facilities
with
design
intake
flows
(
DIF)
of
less
than
50
million
gallons
per
day
(
MGD).
