Document ID: EPA-HQ-OW-2002-0039-0053
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2003-07-09T04:00Z

LT2ESWTR
Toolbox
Guidance
Manual
Proposal
Draft
June
2003
3­
1
Applicability
The
LT2ESWTR
specifies
the
sample
locations
for
systems
with
presedimentation
basins
and
raw
water
off­
stream
storage
(
40
CFR
141.704).
These
locations
are
after
the
basins;
therefore,
this
option
should
not
be
considered
by
systems
with
those
treatment
processes.

Since
the
LT2ESWTR
requires
that
alternative
monitoring
must
be
conducted
concurrently
with
source
water
monitoring
(
40
CFR
141.725(
b)(
1)),
this
toolbox
option
needs
to
be
evaluated
prior
to
the
start
of
source
water
monitoring.
3.0
Alternative
Source/
Intake
3.1
Introduction
Changing
the
water
source
or
intake
location
can
improve
source
water
quality
and
reduced
treatment
requirements
for
the
Long
Term
2
Enhanced
Surface
Water
Treatment
Rule
(
LT2ESWTR).
The
rule
states
that
systems
may
be
classified
in
a
bin
based
on
monitoring
of
an
alternative
source
or
intake
location
or
monitor
using
an
alternative
procedure
for
managing
the
timing
of
withdrawal;
this
monitoring
must
be
conducted
concurrently
with
their
existing
intake
or
withdrawal
practice.
After
monitoring,
a
system
would
then
choose
which
source,
intake
location,
or
intake
procedure
it
will
use
based
on
bin
classification
results.
(
40
CFR
141.725(
b)(
1))

This
chapter
discusses
the
concurrent
monitoring
options
of
changing
sources,
moving
the
plant
intake,
and
managing
the
timing
or
level
of
withdrawal
and
is
organized
as
follows:

3.2
Changing
Sources
­
discusses
factors
to
be
considered
in
changing
sources,
including
advantages
and
disadvantages
and
influence
of
source
water
characteristics
on
existing
treatment
requirements.

3.3
Changing
Intake
Locations
­
discusses
the
applicability
of
changing
the
intake
locations
and
variables
affecting
Cryptosporidium
concentrations
in
reservoirs,
lakes,
streams,
and
rivers.

3.4
Changing
Timing
of
Withdrawals
­
describes
different
approaches,
and
advantages
and
disadvantages
to
changing
the
timing
of
withdrawals.
Chapter
3
­
Alternative
Source/
Intake
LT2ESWTR
Toolbox
Guidance
Manual
Proposal
Draft
June
2003
3­
2
3.2
Changing
Sources
In
order
to
be
able
to
relocate
an
intake
to
a
different
source,
a
system
would
need
to
identify
an
unallocated
source
within
a
reasonable
distance
of
its
treatment
plant.
The
new
source
would
require
sufficient
unallocated
flow
to
meet
the
system's
needs,
including
those
for
peak
flow
and
future
growth.
The
effect
of
the
different
water
quality
on
the
existing
treatment
process
should
also
be
considered.

3.2.1
Advantages
and
Disadvantages
The
main
advantage
of
changing
sources
as
an
approach
to
dealing
with
higher
Cryptosporidium
levels
in
a
current
source
is
avoiding
the
addition
of
a
new
treatment
process.
The
capital
expense
of
a
new
well
or
new
intake
may
be
less
than
the
expenses
associated
with
installing
and
operating
a
new
treatment
technology.
In
addition
to
having
a
lower
Cryptosporidium
concentration,
the
new
source
may
also
have
better
water
quality
that
could
reduce
treatment
costs.
Systems
should
assess
any
potential
new
source
to
ensure
its
integrity,
quantity,
and
quality.
In
addition,
switching
to
a
new
source
often
requires
approval
by
the
State.

A
disadvantage
associated
with
changing
sources
is
that
the
different
source
water
may
respond
differently
to
the
treatment
train
already
existing
at
the
plant.
This
may
require
changes
in
plant
operating
procedures,
such
as
changing
the
type
and
amount
of
coagulant
added,
the
length
of
filtration
runs,
and
the
dose
of
disinfectant
added.
Another
disadvantage
is
that
the
source
may
be
lower
in
Cryptosporidium
concentration
but
have
higher
concentrations
of
other
contaminants.
There
may
also
be
legal
and
environmental
issues
associated
with
tapping
a
new
source.
Plant
standard
operating
procedures
(
SOPs)
should
be
updated
if
a
new
source
is
added.
Finally,
the
cost
of
installing
a
new
intake
and
transmission
line
should
be
considered;
depending
on
the
location
of
the
source
or
intake
in
relation
to
the
plant
or
to
existing
transmission
lines,
a
new
source/
intake
could
be
more
expensive
than
other
toolbox
options.

3.2.2
Evaluation
of
Source
Water
Characteristics
for
Existing
Treatment
Requirements
If
a
new
source
is
to
be
introduced
to
an
existing
treatment
plant,
the
treatability
of
the
new
water
by
the
existing
process
should
be
considered.
For
example,
in
a
conventional
treatment
train
consisting
of
coagulation,
sedimentation,
and
dual
media
filtration,
each
source
water
will
have
unique
coagulation
properties
depending
on
its
characteristics.
Organic
content,
alkalinity,
and
pH
all
affect
the
coagulation
process.
Consequently,
water
quality
parameters
including
pH,
alkalinity,
total
organic
carbon
(
TOC),
UV
254,
turbidity,
and
iron
and
manganese
concentrations
should
be
measured
and
evaluated
against
the
existing
water
and
the
treatment
train.
If
coagulation
is
used
as
a
part
of
the
treatment
process,
jar
tests
should
be
conducted
to
determine
the
coagulation
and
settling
properties
of
the
new
water
and
to
aid
in
calculating
the
Chapter
3
­
Alternative
Source/
Intake
LT2ESWTR
Toolbox
Guidance
Manual
Proposal
Draft
June
2003
3­
3
required
dose
of
coagulant.
(
See
American
Water
Works
Association
(
AWWA)
Manual
M37,
Operational
Control
of
Coagulation
and
Filtration
Processes
for
more
information
on
jar
testing.)
Pilot
plant
studies
can
also
help
determine
the
treatability
of
a
proposed
new
source.

3.3
Changing
Intake
Locations
Another
method
for
reducing
Cryptosporidium
source
concentrations
is
to
move
the
intake
within
the
same
source.
This
could
involve
relocating
an
intake
within
a
source
or
changing
the
depth
from
which
the
intake
draws.

3.3.1
Applicability
Relocating
an
intake
can
be
a
good
strategy
if
an
obvious
source
of
Cryptosporidium
is
present
which
can
easily
be
avoided
by
moving
the
location
of
the
intake.
One
example
of
such
a
situation
is
if
an
intake
could
be
moved
upstream
of
a
municipal
wastewater
discharge
in
a
river,
where
it
had
previously
been
located
downstream
of
the
discharge.

3.3.1.1
Advantages
and
Disadvantages
One
advantage
of
moving
the
location
of
an
intake
is
its
potentially
low
relative
cost,
if
the
distance
the
intake
must
be
moved
is
relatively
short.
This
option
could
be
particularly
attractive
if
an
existing
intake
structure
can
be
used
to
withdraw
water
from
a
different
depth,
resulting
in
decreased
Cryptosporidium
concentrations.

Disadvantages
could
include
significant
amounts
of
excavation
and
piping,
as
well
as
additional
pumping
if
the
intake
must
be
relocated
a
considerable
distance.
Also,
altering
the
intake
may
not
bring
the
desired
reduction
or
provide
any
additional
protection
against
future
increases
or
spikes
in
Cryptosporidium
concentration.

3.3.2
Reservoirs
and
Lakes
Several
variables
can
affect
the
concentration
of
Cryptosporidium
at
a
particular
location
in
a
reservoir
or
lake,
including
the
intake
depth,
the
way
in
which
the
lake
mixes,
the
thermal
properties
of
the
lake,
and
the
proximity
of
the
intake
to
streams
and
other
discharges.
It
is
recommended
that
a
water
system
develop
an
SOP
for
water
withdrawal
based
on
the
specific
conditions
of
the
waterbody
being
used
as
the
source.
Chapter
3
­
Alternative
Source/
Intake
LT2ESWTR
Toolbox
Guidance
Manual
Proposal
Draft
June
2003
3­
4
3.3.2.1
Depth
The
intake
depth
can
significantly
change
the
quality
of
the
water
being
drawn
and
used.
In
general,
shallow
intakes
are
more
likely
to
draw
water
exposed
to
recreational
activity
and
surface
water
runoff.
Deeper
intake
locations
are
often
more
protected
from
sources
of
Cryptosporidium,
unless
an
intake
location
is
so
deep
that
it
draws
water
containing
re­
suspended
material
from
the
lake
or
reservoir
bottom.
Water
systems
are
often
well­
advised
to
draw
water
from
intermediate
depths,
where
they
can
avoid
higher
oocyst
concentrations
that
may
exist
near
the
lake
or
reservoir
surface,
and
also
avoid
particles
that
may
be
stirred
up
near
the
bottom.

3.3.2.2
Stratification
and
Mixing
Another
factor
that
can
affect
the
depth
profile
of
Cryptosporidium
in
a
lake
or
reservoir
is
the
amount
of
stratification
or
mixing
present.
Larger
lakes
and
reservoirs
often
stratify,
especially
in
the
summer
months,
forming
a
hypolimnion
(
a
cold
lower
layer)
and
an
epilimnion
(
a
warm
upper
layer)
separated
by
a
thermocline.
There
is
very
little
mixing
between
these
layers
when
a
lake
is
strongly
stratified.
Particles
may
settle
through
the
layers,
but
there
is
little
other
mixing.
The
epilimnion
is
often
well
mixed
because
of
the
mixing
action
of
wind.
Therefore,
it
is
likely
that
Cryptosporidium
may
be
present
at
uniform
concentrations
throughout
the
epilimnion.
Cryptosporidium
oocysts
that
have
attached
to
particles
and
settled
will
have
a
concentration
gradient
in
the
hypolimnion.
The
shape
of
any
concentration
gradient
will
depend
on
local
conditions
such
as
temperature,
stream
inflows,
and
particle
settling
rates.
Lakes
or
reservoirs
that
are
strongly
stratified
and
have
a
high
input
of
organics
can
often
develop
anoxia
in
the
hypolimnion.
Therefore,
all
water
quality
parameters
should
be
considered
before
determining
the
depth
from
which
to
draw
the
water.
Extremely
high
withdrawal
rates
may
provide
enough
energy
to
overcome
stratification
and
draw
from
the
layer
outside
of
where
the
intake
is
located.

3.3.2.3
Proximity
to
Inflows
The
proximity
of
the
intake
to
stream
inflows
may
affect
the
quality
of
the
intake.
Streams
carrying
agricultural
or
urban
runoff
can
cause
water
quality
degradation
if
located
too
close
to
a
source
water
intake.
States
et
al.
(
1998)
reported
an
increase
in
Cryptosporidium
concentrations
with
wet
weather
events,
particularly
as
the
sampling
location
became
closer
to
the
contamination
source.
Kortmann
(
2000)
reported
a
system
substantially
reduced
coliform
bacteria
in
their
source
water
by
moving
their
intake
further
away
from
a
stream
which
drained
an
agricultural
area
and
by
installing
an
artificial
partition
in
the
reservoir
to
limit
the
exchange
of
water
between
the
stream
input
and
the
rest
of
the
lake.
Chapter
3
­
Alternative
Source/
Intake
LT2ESWTR
Toolbox
Guidance
Manual
Proposal
Draft
June
2003
3­
5
3.3.3
Streams
and
Rivers
There
are
several
factors
to
consider
when
deciding
where
to
locate
an
intake
on
a
river
including
depth,
flow
hydraulics,
seasonal
effects,
and
upstream
sources
of
contamination.

3.3.3.1
Depth
Depth
is
not
as
likely
to
affect
Cryptosporidium
concentrations
in
small
rivers
and
streams
as
it
is
in
lakes
and
reservoirs.
Fast
moving
or
shallow
streams
are
likely
to
be
fairly
mixed
across
all
depths.
In
contrast,
deeper
and
slower
moving
rivers
may
be
less
mixed
and
may
show
some
concentration
gradient
of
Cryptosporidium
with
unattached
oocysts
being
greater
near
the
surface
and
oocysts
attached
to
particles
being
greater
near
the
bottom.
In
rivers
and
streams,
intakes
located
near
the
bottom
are
more
likely
to
draw
sediment
and
other
particles
resuspended
from
the
bottom.

3.3.3.2
Flow
and
River
Hydraulics
Hydraulics
of
the
river
and
the
flow
around
the
intake
are
extremely
important
in
determining
the
quality
of
water
that
enters
the
system.
In
general,
portions
of
a
stream
or
river
with
lower
velocities
and
less
turbulence
will
contain
less
sediment
and
possibly
less
Cryptosporidium
oocysts.
Care
should
also
be
taken
to
make
sure
that
the
design
of
the
intake
does
not
cause
turbulence
which
might
stir
up
sediments.

3.3.3.3
Upstream
Sources
of
Contamination
Any
potential
sources
of
contamination
upstream
of
a
new
intake
should
be
identified
and
their
impact
considered
with
respect
to
both
biological
and
chemical
contamination.
Contaminant
sources
of
particular
concern
for
Cryptosporidium
include
animal
feeding
operations
and
sewage
outfalls.
If
an
intake
cannot
be
located
upstream
of
such
a
source,
then
locating
it
as
far
as
possible
downstream
to
allow
time
for
particles
to
settle
may
be
the
next
best
alternative.
Analyses
of
the
vulnerability
of
a
stream
source
should
be
made
on
a
regular
basis.
Any
changes
in
the
vulnerability
of
a
source
to
Cryptosporidium
or
other
contaminants
should
be
reported
to
the
primacy
agency.

3.3.3.4
Seasonal
Effects
Cryptosporidium
concentrations
tend
to
be
higher
during
runoff
events,
particularly
in
the
spring.
Although
it
is
probably
not
feasible
to
cease
withdrawals
during
such
incidents,
it
may
be
possible
to
alter
flow
rates
and
coagulant
doses
to
offset
the
effect
of
such
events.
Chapter
3
­
Alternative
Source/
Intake
LT2ESWTR
Toolbox
Guidance
Manual
Proposal
Draft
June
2003
3­
6
3.4
Changing
Timing
of
Withdrawals
The
LT2ESWTR
allows
the
option
of
changing
the
timing
of
withdrawals
to
obtain
a
lower
source
water
concentration
of
Cryptosporidium
for
bin
assignment
(
40
CFR
141.725(
b)(
1)).
For
implementation
of
this
option,
the
system
must
then
continue
to
draw
source
water
in
the
same
manner
as
conducted
for
Cryptosporidium
source
water
monitoring
(
40
CFR
141.725(
b)(
3)).
The
operating
conditions
under
which
the
samples
were
collected
for
the
LT2ESWTR
must
be
reported
and
submitted
to
the
State
with
the
monitoring
results
(
40
CFR
141.725(
b)(
2)).

3.4.1
Toolbox
Selection
Considerations
As
stated
above,
the
change
in
timing
must
be
consistent
during
Cryptosporidium
monitoring
and
during
routine
operation
after
monitoring.
Additionally,
the
LT2ESWTR
does
not
allow
source
water
monitoring
to
deviate
from
a
predetermined
schedule
by
more
than
2
days,
unless
extreme
conditions
or
situations
arise
that
prevent
sampling
(
40
CFR
141.703(
b)
and
(
c)).
Given
these
limitations,
the
following
provides
examples
of
recommended
and
not
recommended
approaches.

Recommended
Approaches
°
Changing
the
timing
of
withdrawal
on
a
daily
basis
(
e.
g.,
from
the
afternoon
to
morning
to
avoid
suspended
material
stirred
up
by
recreational
water
use).

°
Use
a
water
quality
indicator
to
avoid
short­
term
increases
in
Cryptosporidium
due
to
short­
term
weather
or
source
water
contamination
events.
For
example,
if
a
system
routinely
experiences
a
spike
in
turbidity
and
subsequently,
Cryptosporidium,
for
a
12­
24
hour
period
following
a
storm
event,
then
the
system
may
choose
to
set
up
a
monitoring
plan
that
delays
withdrawal
for
a
24
hour
period
when
detecting
a
spike
in
turbidity.

Approaches
Not
Recommended
°
Limiting
withdrawal
in
response
to
seasonal
effects
or
weather
effects
lasting
on
the
order
of
days.
This
would
be
a
difficult
monitoring
strategy
to
follow
and
stay
in
compliance
with
the
2
day
sampling
window.

3.4.1.1
Advantages
and
Disadvantages
The
advantage
of
changing
the
timing
of
withdrawals
is
it
requires
no
treatment
changes,
only
a
change
in
operations.
For
systems
with
multiple
sources
it
also
allows
the
greatest
flexibility
in
meeting
water
quality
goals.
Chapter
3
­
Alternative
Source/
Intake
LT2ESWTR
Toolbox
Guidance
Manual
Proposal
Draft
June
2003
3­
7
A
disadvantage
of
relying
on
changing
withdrawals
to
lower
Cryptosporidium
concentrations
is
that
it
may
result
in
decreased
flexibility,
since
systems
must
follow
the
same
withdrawal
practices
they
did
during
Cryptosporidium
source
water
monitoring.
If
electing
to
practice
a
withdrawal
approach
that
defers
withdrawal
during
likely
Cryptosporidium
events,
then
a
system
may
need
some
raw
water
storage
capacity.
Chapter
3
­
Alternative
Source/
Intake
LT2ESWTR
Toolbox
Guidance
Manual
Proposal
Draft
June
2003
3­
8
References
Gregory,
J.
1994.
"
Cryptosporidium
in
water:
Treatment
and
monitoring
methods."
Filtr.
Sep.
31(
3):
283­
289.

Kortmann,
R.
W.
2000.
Reservoir
management
approaches
exemplified."
Proceedings
of
American
Water
Works
Association
Water
Quality
Technology
Conference.

Kortmann,
R.
W.
1989.
Raw
water
quality
control:
an
overview
of
reservoir
management
techniques.
Journal
of
the
New
England
Water
Works
Association.
December
1989.
pp.
197­
220.

Swabby­
Cahill,
K.
D.,
G.
W.
Clark,
and
A.
R.
Cahill.
"
Buoyant
qualities
of
Cryptosporidium
parvum
oocysts."
AWWA
Water
Quality
Technology
Conference.
Boston:
AWWA,
1996.

Walker
M.
J.,
C.
D.
Montemagno,
and
M.
B.
Jenkins.
1998.
"
Source
water
assessment
and
nonpoint
sources
of
acutely
toxic
contaminants:
A
review
of
research
related
to
survival
and
transport
of
Cryptosporidium
parvum."
Wat.
Resour.
Res.
34(
12):
3383­
3392.