NPDES MONITORING RECOMMENDATIONS
TO IMPROVE CONTAMINANT
LOADING DATA AVAILABILITY
Submitted to:
U.S. Environmental Protection Agency
Region 10
Prepared by:
Cooper Consultants, Inc.
1750 112th Avenue NE, Suite C-225
Bellevue, Washington 98004
and
Envirosphere Company
10900 NE 8th, Fifth Floor
Bellevue, Washington 98004
October 1985
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TABLE OF CONTENTS
1.0 INTRODUCTION
2.0 THE NPDES PERMITTING PROCESS
3.0 DISCHARGE CHARACTERIZATION .
3.1 IDENTIFICATION OF DISCHARGE CONSTITUENTS 5
3.2 DETERMINATION OF VARIABILITY AND INTERRELATIONSHIPS . 6
3.3 DISTRIBUTION OF CONTAMINANTS BETWEEN THE
DISSOLVED AND SUSPENDED PHASE 8
4.0 STANDARDIZED REPORTING 10
5.0 COST OF EXPANDING THE NPDES MONITORING REQUIREMENTS ... 12
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1.0 INTRODUCTION
Effective management decisions concerned with the control of toxic
chemicals entering Puget Sound require the identification of the
contributing sources and quantification of the contaminant mass loading
associated with these sources. Quantitative knowledge of chemical
contaminant inputs into the Sound compiled with a good understanding of
the transport and or fate of these materials in the receiving waters of
the Sound is critical to: (1) the estimation of a toxic chemical mass
balance, (2) the determination of the relationship between contaminant
input, environmental distribution and effects, and (3) establishment
of a realistic control, compliance and enforcement strategy.
A number of recently completed studies supported by EPA, Metro, and
NOAA have attempted to evaluate contaminant mass loading to Puget
Sound. The data deficiencies and inadequacies encountered during
preparation of these studies emphasize the limitations of the
historical database available to quantify contributions of priority
pollutants from point source discharges. These limitations are further
emphasized by the following statistics obtained from the EPA NPDES
Source Ranking Database.
Of the current list of 354 wastewater sources permitted to discharge
Into the Puget Sound Basin, only 55 have Class II inspections on file.
These inspections are analyses performed by EPA to confirm the
concentrations of reported pollutants. Priority pollutant scans have
only been performed for 5 discharges by the Washington Department of
Ecology. Forty-four sources have NPDES permit applications indicating
toxic organics in their effluents and 24 report metals in their DMR's.
Point source discharges to Puget Sound are regulated under the National
Pollutant Discharge Elimination System (NPDES) permit program. The
current NPDES permitting regulations therefore, contain the necessary
framework within which to obtain the types of information required to
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compute contaminant loading to Puget Sound. A few revisions and
additions could be made within the existing NPDES program to
substantially enhance the availability of contaminant loading data.
This report presents a summary of the NPDES permit program and
recommendations for enhancement of NPDES permit requirements to provide
the discharge characterization data required to compute total loading
of priority pollutants to Puget Sound from point source discharges.
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2.0 THE NPDES PERMITTING PROCESS
The current NPDES permitting program is designed to ensure that
appropriate effluent limits are established and observed. The permit
applicant provides information on the activity producing the discharge
and expected or measured discharge composition and flow rates. Based
on this information provided by the applicant, on guidelines for
similar discharges, the treatment processes utilized, receiving water
quality, and potential impacts appropriate effluent limits and
monitoring requirements are established. However, for most permits,
the differences among discharges even for similar industries requires a
case-by-case analysis. The properties of the discharge and receiving
water, specifically the variability of discharge and the hazard of the
pollutants, dictate in part what scope of monitoring will be required.
Generally, enough monitoring will be required to ensure that
representative samples are obtained and analyzed, and that the
discharge remains in compliance with the permit effluent limitations.
The NPDES program for the Puget Sound Basin is administered by the
Water Quality Planning and Management Section of the Water Quality
Division in the Washington Department of Ecology (WDOE). The Water
Permits and Compliances Branch of the Water Division in EPA Region 10
administer's permits for discharges from federal facilities and
provides technical assistance to WDOE. The Water Quality Section
reviews the permit applications, develops the applicable effluent
limitations and monitoring requirements, and then reviews the discharge
monitoring reports (DMR) and inspection reports. NPDES permit
applications are handled by staff assigned to the following specific
industries: coal mining, ore mining, placer mining, oil and gas
extraction, seafood processing, pulp and paper, petroleum refineries,
metal-finishing, and municipalities. With this categorization by
industry, the permits are developed by staff who are knowledgeable of
the processes and wastewater characteristics specific to that industry
and familiar with the permit requirements for similar discharges.
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The current NPDES permitting philosophy is protection of water quality
without excessively burdening the discharger. Permits are generally
written to require the minimum amount of information which will
adequately characterize the effluent. For example, a small municipal
waste treatment plant may be required to measure residual chlorine as
an index of disinfection with only occasional measurement of fecal
cdliform. A discharge containing several metals may only be monitored
for one metal, the most sensitive indicator, if the metal
concentrations are generally proportional to one another. Requirements
for an effluent stream with high variability often specify collection
of just a composite sample in order to obtain representative pollutant
concentrations.
Reviews and revisions are steps included in the current permitting
process. After the effluent limits and monitoring requirements are
developed, a 30-day comment period begins in which the applicant, other
agencies, and concerned parties may provide input to the proposed
permit requirements. After permit conditions have been established,
formal revisions to the permit can be made if sufficient evidence is
presented to warrant more stringent requirements or eliminate
unneccessary measurements.
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3.0 DISCHARGE CHARACTERIZATION
To estimate mass loading from point sources, several types of
Information about the discharges are required. These Include:
o identification of all contaminant constituents in the discharge
o determination of the variability of and interrelationships
between the discharge flow rate and constituents concentrations
o distribution of the contaminant between the dissolved and
suspended phase
The manner in which this information may be obtained for a given
discharge and the way that this information may be used to determine
discharge monitoring requirements are discussed below.
3.1 IDENTIFICATION OF DISCHARGE CONSTITUENTS
During the Initial phases of permitting, all potential contaminants in
the discharge must be Identified. As discussed, the case-by-case permit
decision process is in place. Historically, however, permit conditions
have been specified for only conventional pollutants and occasionally
selected organlcs and metals. This is because detailed analytical
techniques required for priority pollutant organics have only become
available in relatively recent time. To improve the availability of
data required to estimate total contaminant loading to Puget Sound, the
case-by-case evaluations simply need to expand the overall emphasis to
Include other constituents and the 30 priority pollutants of particular
Interest in Puget Sound.
To effectively establish monitoring requirements that will provide the
data to estimate mass loading, the permitting staff need more specific
Information about the constituents 1n the applicant's effluent . In
addition to the information required on the Standard Form C application,
the applicant should be asked to provide more detailed information on
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facility operations and waste abatement practices that would affect the
composition of the wastewater, and a wastewater characterization based
on actual analysis instead of just a best estimate. Permitting staff
should become more familiar with recent permit requirements for similar
discharges in other regions as well as the data obtained from DMR's and
inspection reports. If the necessary constituent information cannot be
provided by the applicant or found in EPA's files, then the staff should
research other agency files and applicable literature in order to
determine what parameters need to be monitored. Most of the above
suggestions are being addressed by the Permit Section, but to a limited
degree, because most of the staff have multiple assignments and other
responsibilities. Therefore, the addition of qualified staff should be
seriously considered.
Where there is reason to suspect that any of the priority pollutants
will be present in a discharge, limitations and monitoring requirements
must be established for these pollutants. In the instances where
available information is not sufficient to develop an initial discharge
characterization, a priority pollutant scan must be required. This will
be the most simple and accurate means to ensure that contaminants in the
discharge have been identified.
3.2 DETERMINATION OF VARIABILITY AND INTERRELATIONSHIPS
Mass loading is calculated as the product of concentration and
volumetric flow. Very accurate measurements of mass loading require
that concentrations and volumetric flow rates be measured simultaneously
and continuously by automated equipment during all periods of
discharge. However, highly accurate estimates are costly to obtain and
do not necessarily provide information that is any better suited for
determining compliance or estimating mass loadings than somewhat less
accurate estimates.
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The types of monitoring required to accurately characterize a discharge
depend primarily on the variability of the discharge flow rate and/or
constituent concentrations. For continuous discharges with fairly
consistent constituent concentrations, random samples can be used to
obtain average values to characterize the effluent and monitor for
compliance.
For intermittent discharges, mass loadings can be estimated from
averaged pollutant concentrations and the quantity, duration, and
frequency information required in items 10 and 11 of the Standard
Form C. Monitoring requirements for both compliance and mass loading
calculations should be tailored to obtain representative data depending
on the discharge volume and occurrence, and whether the pollutant
concentrations for each occurrence vary substantially from the average.
Where Intermittent discharge concentrations are known to be quite
variable, measurement of each discharge event may be 1n order during the
Initial monitoring period to establish the expected variability;
discharges with nore consistent concentrations can be characterized by
composite samples.
The descriptive information currently required of the applicant for a
NPDES permit (daily average, minimum and maximum for flow and
constituents) is adequate for continuous or intermittent flows where the
contaminant concentrations vary in a consistent manner close to the
average. However, if the concentrations fluctuate inconsistently and
vary widely about the average or the discharge is variable in both flow
and/or constituents, then additional information about the activity
producing the discharge, such as process mass balances and chemical
inputs, should be required from the applicant. Enough information about
the waste abatement practices must be obtained to determine the
Interrelationships between constituents and flows. Based on this
additional knowledge, more effective monitoring requirements can be
established such as frequent measurements of instantaneous flow rates
and concentrations during specified discharge occurrences. From these
measurements, an average instantaneous mass loading value or average
concentration and total flow values might be calculated.
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In order to estimate an annual mass loading into Puget Sound, one must
be able to obtain the total volume discharged on an annual basis for all
discharges. Thus, for all except continuous flows, the frequency and
duration of flow must be indicated. Specifically, discharge duration in
hours per day, days per week, weeks or months per year, and periods of
variation must be reported. From the DMR's, average concentrations can
be calculated for the total discharge volume or discharge intervals as
applicable.
3.3 DISTRIBUTION OF CONTAMINANTS BETWEEN THE DISSOLVED
AND SUSPENDED PHASE
When the NPDES permitting requirements were developed, environmental
concern was focused primarily on the impacts of the discharge on water
quality, i.e., concentrations of contaminants in the water column.
Accordingly, only total concentration of metals were specified in the
water quality criteria. Potential Impacts resulting from contaminated
sediments are now a recognized concern and environmental awareness has
expanded to look at the entire water body and associated ecosystems. In
addition, the stability of the contaminant in the marine environment as
well as its bioavailability and toxicity have been found to vary widely
depending on its chemical and physical form in the discharge. Although
no extraction technique has been established which is representative of
the actual availability of a contaminant, its distribution between
dissolved and suspended phases is useful in understanding the immediate
transport.
Contaminant loading estimates for Puget Sound will be most useful if it
is possible to differentiate between those contaminants which will
remain dissolved in the water column and those in the suspended solid
phase which will eventually settle out. The total values reported now
are essentially a summation of both the dissolved and suspended values.
Therefore, to properly characterize contaminants in the permit
application, presentation of both the dissolved and suspended solids
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phases should be required. Both phases should also be reported in the
early stages of monitoring. After a relationship between the dissolved
and total concentrations is established, then the remainder of the DMR's
need only present total values.
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4.0 STANDARDIZED REPORTING
In order to facilitate data compilation and calculation of contaminant
mass loading associated with point sources, the present NPDES format for
applications and monitoring reports should be revised. The reporting
format and subsequent information currently supplied by the discharger
is suitable for checking compliance but are either inadequate or
difficult to use for mass loading calculations. The required formats
should be expanded to not only include the 30 priority pollutants of
primary interest in Puget Sound as applicable, but to also require the
flow and concentration data in units conducive to accurate mass loading
estimation.
Units of measurements should be standardized for consistency in data
compilation and determination of compliance. Concentration units of
parts per million (ppm) and parts per billion (ppb) (or the equivalent
mg/1 and ug/1, respectively) are common and are useful in calculating
mass loading. Trace organic compounds should be expressed in ppb units
based on relatively low expected concentrations. Metals, COD, BOD, TKN,
TSS and other common water quality parameters should be expressed as
ppm.
Flow rates should be measured and reported in standardized units both
within a permit application and DMRs and among all discharge permits.
Units of cubic meters per second (m /s) may be preferable to cubic
feet per second or gallons per day due to the increasingly common use of
the metric system. These units will allow simple calculation of mass
loading in units of kg/s:
(contaminant A) kg/s = [A]mg/l x (flow) m /s x 1,000
(contaminant B) kg/s = [B]Mg/l x (flow) m3/s x 1,000,000
Annual estimates of loading may be calculated by multiplying the
instantaneous mass loading (kg/s) by the amount of time during the year
the discharge occurs in seconds. Annual loading may also be estimated
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by multiplying an average concentration by total flow. Flow units of
cubic feet per second and gallons per day, although commonly used,
require more involved conversions to obtain loading values.
The seasonal and time variations of mass loading are also often
pertinent. Thus, dates and times of measurements should be reported and
included in monitoring databases in order to evaluate time variability
of discharges and to quantify loading over desired time intervals. If
climate, particularly precipitation, influences the discharge volume or
composition, some statement to this effect should be recorded in the
DMRs.
Another aspect of data standardization which needs to be considered is
the use of different analytical methods and protocols by laboratories.
EPA is currently working on this problem through its Water Quality
Management Program to develop consensus methods for measuring
environmental variables in Puget Sound. The focus of this effort is to
encourage all investigations whether for research or permit monitoring
to use acceptable and standardized methods. Specifically applicable to
wastewater analyses are the following efforts toward uniformity:
o Clarify the use of internal versus external standards,
o Reduce the options in QA protocols in reference to blanks,
spikes, and duplicates,
o Establish-a standard for rejection of data based on background
interference, and
o Specify an acceptable method for extraction of organics fron
water samples.
Standardization of acceptable methods and protocols will result in a
greater degree of reproducibility and consistency among the laboratory
analyses of the 30 priority pollutants of interest in Puget Sound. This
will enhance the acceptance of combining databases from different
studies and agency files for mass-loading estimates.
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5.0 COST OF EXPANDING THE NPDES MONITORING REQUIREMENTS
The cost to the discharger to provide the additional information on
flows and constituents will consist of costs for sampling, monitoring,
reporting, and chemical analyses. The increases in costs due to the
first three items should not appreciably exceed those costs under the
current program; any cost increases will be associated primarily with
labor. The cost of more frequent and extensive chemical analyses for
additional constituents will be the controlling factor. The number of
parameters required to be analyzed will vary with the discharge
characteristics, but costs on a per chemical basis will provide a useful
estimate.
The following costs were obtained from AM TEST, Inc. for the chemicals
recommended for the Puget Sound mass loading study.
Cost for
Analysis
Six Priority Pollutant Metals
Arsenic, cadmium, copper, and lead
Mercury
Zinc
(Digestion Fee)
Seven Priority Pollutant Organic Compounds
or Compound Groups
Total PCBs
Total Low Molecular Weight PAHs
Total High Molecular Weight PAHs
4 - Methyl phenol
Phenol
Hexachlorobutadiene
DDE and ODD
% 12.00/ea
% 22.00
% 7.00
% 10.00/sample
% 80.00
3150.00
2150.00
2100.00
5100.00
% 90.00
2100.00
$400.00
2400.00
2150.00
2150.00
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o Two Indicator Organic Compounds
2-Methoxyphenol 3100.00 - $150.00
Coprostanol 2100.00 - 2150.00
Costs for individual organics may vary due to preparation techniques,
but typically range $100.00 - 3150.00. In some instances, groups of
organic chemicals may be analyzed together, thereby lowering costs.
Costs specifically for PAHs vary depending upon the method employed with
EPA Method 610 at approximately $150.00 per scan versus EPA Method 625
at $400.00 for just a base/neutral scan. Therefore, the total cost of a
complete priority pollutant scan can range for $1000.00 to $1350.00
depending on the specified detection limits and characteristics of the
wastewater.
As a comparison, the costs of testing just for conventional parameters
may total less than $100.00/sample.
o pH % 5.00
o Biochemical Oxygen Demand (BODg) $ 23.00
o Chemical Oxygen Demand (COD) % 23.00
o Total Suspended Solids $ 10.00
o Specific Conductance $ 6.00
o Settleable Matter $ 6.00
TOTAL $ 73.00
The costs of priority pollutant analyses are such that excessive
monitoring frequency could be prohibitive, especially if several organic
analyses are required. Therefore, efforts should be made during the
application phase to specifically identify priority pollutants of
concern as part of the wastewater characterization. In most cases, the
complete priority pollutant scan would only be required to characterize
a relatively unknown discharge, during the application and/or initial
monitoring phase, to recharacterize a discharge after a change in
process activities before renewing a permit, or during a Class II
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inspection when similar discharges have been found to contain
contaminants of concern. Once the priority pollutants of concern have
been identified in a discharge, only those specific pollutants or
indicator constituents need to be incorporated into subsequent
monitoring requirements.
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