\ I /
United States
Environmental Protection
Agency
Municipal Environmental
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-84-112 Sept. 1984
Project Summary
Predicting Toxic Waste
Concentrations in Community
Drinking Water Supplies:
Analysis of Vulnerability to
Upstream Industrial Discharges
James A. Goodrich and Robert M. Clark
A study was conducted to predict
toxic waste concentrations in com-
munity drinking water supplies along
the Ohio and Kanawha Rivers between
Charleston, West Virginia, and Cincin-
nati, Ohio, using QUAL-II, a water
quality simulation model. Specifically,
a toxics screening method was devel-
oped that can close the potential gap in
the loop between water pollution
control and water consumption. The
project was a response to the lack of
methods for identifying and assessing
communities whose water supplies
were vulnerable to excessive chloroform
and synthetic organics resulting from
industrial pollution and urban and
agricultural runoff.
The most important factors to consider
in identifying vulnerable communities
are potency and persistence of the
pollutants, amount and timing of
discharge of pollutants, storage times
of utilities, and relative location of point
sources and community intakes.
This Project Summary was developed
by EPA's Municipal Environmental
Research Laboratory, Cincinnati, OH,
to announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
On Februarys, 1978, the Environmental
Protection Agency (EPA) proposed a
regulation designed to protect the public
health from organic chemical contam-
inants in drinking water (Federal Regis-
ter, "Environmental Protection Agency
Interim Primary Drinking Water Regula-
tions," Vol. 43, No. 28, Thursday, Febru-
ary 9, 1978, pp. 5756-5780). Originally,
the regulation consisted of two major
parts:
A. A maximum contaminant level
(MCL) that initially required water
treatment systems serving popula-
tions greater than 75,000 to reduce
trihalomethanes (TTHM) to 0.10
mg/L (100 parts per billion), and
B. A treatment technique regulation
that required water systems serving
populations greater than 75,000 to
use GAC in the treatment process
to remove synthetic organic chemi-
cals unless a variance was granted.
Part A was promulgated as proposed on
November 29, 1979; but Part B has been
cancelled as proposed because of the
wide concern over the impact of this
regulation, especially regarding the
procedure granting variances. Are those
utilities within a specified number of
miles downstream from industrial dis-
chargers vulnerable and subject to the
regulation? Or should utilities be granted
a variance if fewer than a certain
number of dischargers exist upstream
from its intakes? This project uses a case
study to answer these questions and to
close the gap that potentially exists in this
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loop between water pollution control and
water consumption.
Through the use of the methodology
developed here, this study predicts which
communities in the case study area will
be vulnerable to (1) background levels of
typical daily discharges, and (2) large,
unexpected spills. Thus the report
describes who is at risk, their relative
levels of risk, and the main factors
contributing to the risk.
QUAL-II, a water quality simulation
model, was used to bring together the
diverse elements of mathematical model-
ing, fluid dynamic's, organic chemistry,
and geography to create an interactive
systems analysis approach that can
have an impact on public policy in
drinking water. Though QUAL-II is less
flexible than other models in simulating
various flow scenarios and less sophisti-
cated in modeling dozens of built-in
parameters and biological and chemical
transformations, the model exhibits a
spatial organization that simplifies
thinking and highlights critical variables
such as the relative locations of utilities
and dischargers and the time of travel.
Procedures
Determining the Case Study
Area
Figure 1 presents the case study area,
and Figure 2 schematically represents
the waste loads, tributaries, and junctions
involved in the water quality modeling.
The contaminants were routed approxi-
mately 200 miles at various flow scenarios
to account for seasonal variations inflow.
The Kanawha River averages 25,000
cubic feet per second (cfs), and the Ohio
River, 125,000 cfs. Time of travel during
average flow is approximately 4.1 days
through the case study area.
Identifying Existing Point
Sources and Communities
The next step in the analysis was to
provide an inventory and description of
existing point sources and communities.
To make a complete and thorough
analysis of a community's vulnerability to
water pollution, nonpoint sources of
pollution as well as the point sources
should be considered. But tremendous
gaps often exist in the land use data,
especially in watersheds involving various
states and regional authorities, and thus
any attempts to model runoff water
quality are pre-empted. To simplify the
analysis, only industrial dischargers and
their wastes are considered in this paper,
though various techniques could be used
to model both municipal discharges and
nonpoint run off.
Calculating Waste Stream
Data for Industrial Dischargers
Typical waste stream data for each
industry type was needed next. For this
analysis, each point source was assigned
a discharge value in parts per billion
based on the best available control
technology (BACT) for the relevant
contaminants coming from each indus-
trial production process. For modeling
purposes, a general idea of a pollutant's
persistence in the stream is required.
Based on extensive calculations and
literature reviewed, disappearance rates
to account for processes such as volatiliz-
ation were assigned to each pollutant
(Maybey, W.R., et al., "Aquatic Process
Data for Organic Priority Pollutants,"
Final Draft Report, Michael W. Slimak,
Project Officer, Monitoring and Data
Support Division, Off ice of Water Regula-
tions and Standards, U.S. Environmental
Protection Agency, Washington, DC,
July, 1981, pp. 409-434.)
Determining Potential Impact
on Public Health
To assess the potential impact on
public health, simulated pollutant con-
centrations for each utility are compared
with the Water Quality Criteria, which
only suggest at this time the concentra-
tions of various pollutants that could be
harmful to human health. The Criteria
take into account toxicity, carcinogenicity,
or organolepticity (taste and odor) of the
pollutants (Personal communication with
Dr. Christopher T. DeRosa, EPA, Environ-
mental Criteria Assessment Office,
1982).
The Water Quality Critera for toxicity
and taste and odor indicate the general
population would be affected by consum-
ing water with a pollutant reaching the
guideline concentration for example,
3,770 fjg/L of cyanide (a toxic), or 300
yug/L phenol (an odor-causing agent). A
tenfold buffer is incorporated in the toxic
and organoleptic standards to take into
account the more sensitive or susceptible
consumers such as those who are very
young, old, pregnant, or ill. Thus segments
of a population could be possibly affected
by 377 yug/L and 30yug/L of cyanide and
phenol, respectively.
The carcinogenic data are estimates of
incremental risks associated with expo-
sures from suspected carcinogens in
drinking water. For example, a person is
assumed to be at the 0.00001 risk level of
developing cancer in his or her lifetime by
drinking 2 L of water with 6.6 yug/L of
benzene daily. The only no-risk level for
carcinogens is zero concentration. Risk is
assumed to be linear, but promoters and
synergism among the pollutants could
actually increase the risk levels.
This analysis is to be undertaken for
daily dischargers of industrial wastes. In
the event of a spill or large accidental
discharge, information regarding the
storage time for each utility is also
necessary. Storage time indicates how
long a utility could operate if the intakes
were closed to prevent the high concen-
tration of pollutants from entering the
system. This factor affects the vulnerability
of a utility.
Creating Various Flow
Scenarios
To assess the vulnerability of commun-
ities to daily discharges of toxic wastes,
three scenarios were created to account
for variations in flow. With the use of
QUAL-II, the applicable priority poll utants
discharged in the case study area (81 out
of the 129 priority pollutants) were
simulated at average, high, and low
flows. Average flow was set at 125,000
cfs, high flow was 220,000 cfs, and low
flow was 35,000 cfs. As the volume of
water increases, so does the mean
velocity in the river channel, thus
reducing the time of travel.
For toxic and organoleptic pollutants,
the flow scenarios are critical in deter-
mining whether a Water Quality Criteria
has been exceeded. Because vulnerability
to carcinogens is evaluated over years of
exposure to pollutants in the drinking
water, carcinogenic risk levels were
initially estimated only at average flows.
In the event of a spill, however, the flow
characteristics can be important even to
carcinogens, since very high concentra-
tions of carbon tetrachloride, for example,
can have an acute health effect. In
addition, regulatory agencies may want
to use higher- or lower-than-average
flows to increase safety factors. As will be
demonstrated later, and contrary to the
conventional wisdom, low flows do not
necessarily exhibit higher pollutant
concentrations than high flows because
of decreased dilution. Utilities can be
vulnerable to different pollutants at
different flows.
Results and Discussion
Organoleptic Pollutants
Only 2 of the 11 organoleptic pollutants
simulated exceeded a level at which
sensitive consumers could be affected by
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Hamilton Co.
Legend
State Boundary
County Boundary
^^^ River
U.S. Highway
^~~ Direction of Flow
g s is
miles
Figure 1. Case study area.
KENTUCKY
WEST VIRGINIA
taste and odor problems. Those two
pollutants are 2-chlorophenol and 2,4-
dichlorophenol. Only during the low-flow
scenario were these pollutants of any
concern to the utilities. Though taste and
odor problems are not dangerous, they
often create greater response than do
reports of possible carcinogens. Histori-
cally, aesthetic considerations have often
been the basis for regulation rather than
public health concerns.
Toxic Pollutants
Toxic pollutants that exceeded the
Water Quality Criteria values at the utility
intakes are listed in Table 1. During low-
flow periods, the sensitive consumers of
all the utilities would have been affected
by cadmium. Ashland consumers would
also be affected by mercury, and Greenup
would have to deal with lead and chromi-
um in addition to cadmium. The simulated
concentrations of mercury exceeded the
criteria guideline for all consumers at
Ironton, Greenup, Portsmouth, Maysville
and Cincinnati during low flow. Because
of greater dilution of the pollutants at
high flow, only mercury remains a con-
cern to some of the utilities. During a
high-flow period, mercury would affect
only the sensitive consumers for the five
utilities mentioned above. At average
flow, cadmium and mercury exceed the
guidelines for sensitive consumers at the
same utilities except for Greenup. Through-
out this analysis, mercury remains a
problem at various levels for all flow
scenarios. Simulated cadmium, lead, and
chromium concentrations would affect
sensitive consumers only during low and
average flow scenarios.
Carcinogenic Pollutants
Analyses of carcinogenic pollutants
proceed differently from the previous
analyses for toxic and organoleptic
pollutants. When assessing risks posed
by carcinogens, no single value signifies
that a health hazard exists for each
pollutant. Rather, the Water Quality
Criteria describe the carcinogenicity at
the 1 x10~5 risk level. These values can be
used to calculate a community's expected
death rate per pollutant per year. Table 2
ranks the utilities from most to least
vulnerable, their river mile location, and
the expected annual deaths attributable
to carcinogens. Table 3 summarizes the
vulnerability for different flow rates.
As expected, the overall number of
expected deaths are lower at high flow
because of the greater dilution of the
pollutants at 220,000 cfs. Only Huntington
and Ashland reverse positions in vulner-
ability at high flow. However, a few
carcinogens do have downstream risk
levels at high flow that exceed those at
average and low flow. Through the total
expected deaths are lower at high flow
than at average and low flows, a few
individual pollutants exhibit higher
concentrations because of their disap-
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Main Stem *
Headwater
Utility A Intake ±
N :
Utility D Intake J
-»
Utility F Intake *.
->
0 30
miles
Utility H Intake «-
L
Ei
Figure 2. Schema
pearance rates, all
average and low fl
time of travel. This
usefulness of mode
parameters, since
masked at various
total expected nurr
lated. Theyexpec
Maysville anaCinci
are greater than at
Huntington, Ashla
exhibit the same res
pollutants that hav
rates and come fror
The decreased time
has not allowed
disappear. Thus util
are at higher risk du
and consequently a
low flow. Utilities c
would exhibit the e
highest risk at Iow1
high flow, regardU
rates.
A great deal o
between the facto
concentration dis
pearance rate. Fig
strate the variabilit
trations at utilities 1
between flow, time
pearance rate.
)
VJ®
^riributary
~?r Headwater
J
g Utility B Intake
-» Utility C Intake
| Utility E Intake
Direction of
UFlow
+ Utility G Intake
O Headwater
(^Junction
-t\Point Source
Loads
^Withdrawals
A
id
tic of the study area.
owing more decay at
ow during the longer
> result points to the
ling the water quality
many pollutants are
flow scenarios by the
ber of deaths calcu-
ted death rates at
nnati during high flow
low flow. Utilities at
id, and Ironton also
ult for a few individual
e high disappearance
n the Kanawha River.
of travel at high flow
for the pollutant to
ties well downstream
ring high flow periods
re at lower risk during
ilosest to the outfalls
xpected risk levels
low and lowest risk at
jss of disappearance
f sensitivity exists
rs of flow, pollutant
:harged, and disap-
iires 3 and 4 demon-
y of pollutant concen-
Dased on the tradeoffs
> of travel, and disap-
4
Table 1 . Summary of Toxic Pollutants Exceeding Health Guidelines A
Average Flow High Flow Low Flow
70% 700% 70% 700% 70% 700%
Utility Level Level Level Level Level Level
Gallipolis, None None None None Cadmium None
Ohio
Huntington, None None None None Cadmium None
West Virgina
Ashland. None None None None Cadmium None
Kentucky Mercury
Ironton, Cadmium None Mercury None Cadmium Mercury
Ohio Mercury
Greenup, Cadmium None Mercury None Cadmium Mercury
Kentucky Lead
Chromium
Portsmouth, Cadmium None Mercury None Cadmium Mercury
Ohio Mercury
Maysville, Cadmium None Mercury None Cadmium Mercury
Kentucky Mercury
Cincinnati, Cadmium None Mercury None Cadmium Mercury
Ohio Mercury
Table 2. Vulnerability of Utilities to Carcinogenic Pollutants at Average Flow
Vulnerability Downstream Expected Number of
Utility Rank Order River Mile Cancer Deaths/ 1 00,000*
Greenup 1 5 334.7 6.47
Portsmouth 2 6 355.5 5.01
Maysville 3 7 408.4 2.99 M
Cincinnati 4 8 462.8 1.56
Ironton 5 4 327.0 0.20
Huntington 6 2 304.3 0.19
Ashland 7 3 319.6 0.18
Gallipolis 8 1 265.8 0.02
^Calculated rates.
Table3. Vulnerability of Utilities to Carcinogenic Pollutants at Various Flow Rates
Expected Death Expected Death Expected Death
Rate at Rate at Rate at
Ut/lity Average Flow High Flow Low Flow
Greenup 6.47(1)* 3.71(1) 19.77(1)
Portsmouth 5.01(2) 3.14(2) 10.42(2)
Maysville 2.99(3) 2.36(3) 2.35(3)
Cincinnati 1.56(4) 1.50(4) 0.56(4)
Ironton 0.20(5) 0.13(5) 0.46(5)
Hungtinton 0.19(6) 0.04(7) 0.44(6)
Ashland 0.18(7) 0.11(6) 0.40(7)
Gallipolis 0.02(8) 0.01(8) 0.07(8)
* Figures in parentheses indicate ranking.
In those two figures, chlorobenzene disappearance to occur. As the time of
and nitrobenzene are identically dis- travel increases, so does the amount of
charged from the same industries. disappearance (thus the low concentra-
However, chlorobenzene exhibits a high tions of pollutant downstream during low
disappearance rate of 0.55/day, compared flow). Figure 4 reinforces this concept
with 0.05/day for nitrobenzene. In Figure because the curves do not cross over at
3, one can see howthe low-flow pollutant various flow rates with the low disap-
concentrations fall far belowthe average- pearance rate. The concentration of
and high-flow levels. The speed at which nitrobenzene at each utility owes most of^
chlorobenzene travels downstream at its decay to the dilution, not to it^l
higher flows does not allow for much disappearance rate hence the almost^
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700 -,
10-
O Average Flow
D High Flow
A Low Flow
I
250
300
350 400
Ohio River Mile Point
450
500
Figure 3. Chlorobenzene concentrations at various flow rates.
100 H
^. 10-
.1
1
§
i
o
o.i-
250
300
350 400
Ohio River Mile Point
450
500
Figure 4. Nitrobenzene concentrations at various flow rates.
parallel curves \n Figure 4 exhibiting the
expected relationships. The low-flow
curve begins to drop a bit more quickly
than the high- and average-flow curves
around the 450-mile point as the low
disappearance rate begins to have an
effect.
Spill Events
Accidental discharges occur in every
conceivable place and manner. QUAL-II
was used to route a 1-day, 60-ton spill
through the case study area from its entry
into the large tributary. The trade-offs
between flow, magnitude of the spill, and
the pollutant's disappearance rate are
critical to downstream concentrations as
in the daily discharge analysis. Table 4
lists the simulated concentrations of a
conservative pollutant as it travels
downstream at low flow. The peak
concentration is not the only important
statistic to be concerned with in a spill
event. The length of time it takes for a spill
to pass the intakes is also vital to a
community's welfare. A slow-passing
spill, though of lower concentration, may
pose a larger problem to a utility with
limited storage capacity than a very high
concentration of a pollutant that passes
quickly.
At high flow, the spill would take only 2
days to pass Gallipolis. Average- and low-
flow scenarios would require 5.5 and
14.32 days, respectively. Gallipolis has
approximately 2 days of storage available
and could close the intakes and not be
harmed during high flow. However, at
average and lowf lows, the spill requires a
longer time to pass, and Gallipolis
officials would need immediate and
accurate information regarding the
discharge to be able to decide when to
close the intakes and reduce the exposure
to the pollutant. Proper timing of the
closure during the peak of the curve cou Id
reduce the health risk immensely.
A worst-case scenario would include a
nondisappearing, highly toxic pollutant
discharged during a low-flow period.
Such a case would not be a total disaster,
however, since the slow time of travel
would allow ample time for downstream
utilities to take precautionary measures,
possibly even altering treatment techni-
ques temporarily to mitigate the health
hazard should storage volumes be
inadequate to serve the community.
Emergency conservation and public
education of the situation could be
instituted to stretch available supplies. A
utility would be wise to have such a
contingency plan developed to ensure
quick and accurate implementation.
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Conclusions
This study examines a functional
region that serves as the source of
drinking water for more than 1.1 million
people, even though it is only a portion of
a watershed. The potential risk posed to
communities results from the gap that
exists between public health considera-
tions and water pollution control stra-
tegies.
The main contribution of this research
has been the development of an interactive
systems analysis approach that can affect
public policy on drinking water. Recent
investigations suggest that much techno-
logical manipulation of the environment
produces new hazards and ameliorates
old ones, and that effective means for
coping with these events call for a
sensitive understanding of natural phe-
nomena as altered by man's actions. To
study these interactions, it was necessary
to collect for the first time a myriad of data
and procedures and place them in an
areal framework that can address prob-
lems between man and his environment.
The water quality simulation model,
QUAL-II, was the mechanism that brought
together diverse elements of mathemati-
cal modeling, fluid dynamics, epidemio-
logy, organic chemistry, and geography.
In addition, QUAL-II has traditionally
modeled only the typical parameters such
as BOD, DO, temperature, etc. In this
analysis, QUAL-II was used to go a step
further in simulating toxic pollutants.
First order decay coefficients were
calculated from other sources and
inserted into the model to estimate the
fate of priority pollutants.
Thus the issue of vulnerability is not a
clear-cut matter of looking for the most
downstream utility or simulating pollu-
tants at an average flow. Very detailed
information on flow probabilities, pollu-
tant characteristics, industrial discharges,
and location are needed.
Table4. Priority Pollutant Spill Simulation (60-ton spill at low flow)
Utility
Gallipolis
Huntington
Ashland
Ironton
Greenup
Portsmouth
Maysville
Cincinnati
Arrival
Time
(days)
2.67
4.51
5.34
5.84
6.34
735
1035
14.00
Leave
Time
(days)
16.99
19.98
21.14
21.97
22.64
24.13
29.25
34.50
Days with
Contamina-
tion
14.32
1547
1580
16.13
1630
16.78
1890
20.50
Peak
Day
7.51
10.02
11.18
11.85
12.51
13.84
1749
21.97
Peak
Concentration
(V9/LJ
28892
209.29
17335
169.41
165.84
149.12
136.37
111.39
The EPA authors James A. Goodrich and Robert M. Clark are with the Municipal
Environmental Research Laboratory, Cincinnati, OH 45268.
The complete report, entitled "Predicting Toxic Waste Concentrations in
Community Drinking Water Supplies: Analysis of Vulnerability to Upstream
Industrial Discharges," (Order No. PB 84-206 531; Cost: $14.50, subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA authors can be contacted at:
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
*USGPO: 1984-759-102-10670
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United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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