United States Office Of Water EPA 823 B 96 007 Environmental Protection ( 4305) June 1996 Agency The Metals Translator: Guidance For Calculating A Total Recoverable Permit Limit From A Dissolved Criterion i FORWARD This document is the result of a successful collaborative effort between the United States Environmental Protection Agency ( USEPA), Electric Power Research Institute ( EPRI), and Utility Water Act Group ( UWAG). Methods and procedures suggested in this guidance are for the specific purpose of developing the metals translator in support of the dissolved metals criteria and should not be interpreted to constitute a change in EPA regulatory policy as to how metals should be measured for such regulatory purposes as compliance monitoring.

This document provides guidance to EPA, States, and Tribes on how best to implement the Clean Water Act and EPA's regulations to use dissolved metal concentrations for the application of metals aquatic life criteria and to calculate a total recoverable permit limit from a dissolved criterion. It also provides guidance to the public and to the regulated community on appropriate protocols that may be used in implementing EPA's regulations. The document does not, however, substitute for EPA's regulations, nor is it a regulation itself. Thus, it cannot impose legally binding requirements on EPA, States, or the regulated community, and may not apply to a particular situation based upon the circumstances. EPA may change this guidance in the future, as appropriate.

This document will be revised to reflect ongoing peer reviews and technical advances and to reflect the results of planned as well as ongoing studies in this technically challenging area. Comments from users will be welcomed. Send comments to USEPA, Office of Science and Technology, Standards and Applied Science Division ( 4305), 401 M Street SW, Washington, DC 20460.

Tudor Davies, Director Office of Science and Technology ii ABSTRACT On October 1, 1993, in recognition that the dissolved fraction is a better representation of the biologically active portion of the metal than is the total or total recoverable fraction, the Office of Water recommended that dissolved metal concentrations be used for the application of metals aquatic life criteria and that State water quality standards for the protection of aquatic life ( with the exception of chronic mercury criterion) be based on dissolved metals. Consequently, with few exceptions, each metal's total recoverable based criterion must be multiplied by a conversion factor to obtain a dissolved criterion that should not be exceeded in the water column. The Wasteload Allocations ( WLA) or Total Maximum Daily Loads ( TMDLs) must then be translated into a total recoverable metals permit limit.

By regulation ( 40 CFR 122.45( c)), the permit limit, in most instances, must be expressed as total recoverable metal. This regulation exists because chemical differences between the effluent discharge and the receiving water body are expected to result in changes in the partitioning between dissolved and adsorbed forms of metal. As we go from total recoverable to dissolved criteria, an additional calculation called a translator is required to answer the question " What fraction of metal in the effluent will be dissolved in the receiving water?" Translators are not designed to consider bioaccumulation of metals.

This technical guidance examines what is needed in order to develop a metals translator. The translator is the fraction of total recoverable metal in the downstream water that is dissolved; that is, the dissolved metal concentration divided by the total recoverable metal concentration. The translator may take one of three forms. ( 1) It may be assumed to be equivalent to the criteria conversion factors. ( 2) It may be developed directly as the ratio of dissolved to total recoverable metal. ( 3) Or it may be developed through the use of a partition coefficient that is functionally related to the number of metal binding sites on the adsorbent in the water column ( i. e., concentrations of TSS, TOC, or humic substances).

Appendix A illustrates how the translator is applied in deriving permit limits for metals for single sites and as part of a TMDL for multiple sources. Appendix B presents some indications of site specificity in translator values. Appendix C illustrates the process of calculating the translator. Appendix D provides some detail of a statistical procedure to estimate sample size. Appendices E and F present information on clean sampling and analytical techniques which the reader may elect to follow. This material ( E and F) is presented only to assist the reader by providing more detailed discussion rather than only providing literature citations; these procedures are not prescriptive. iii ACKNOWLEDGMENT Many people have contributed long hours reviewing and editing the many drafts of this document. The success of technical guidance documents, such as this one, depends directly on the quality of such reviews and the quality of the reviewers suggestions. As such, we thank the many reviewers for their contributions. We wish to express our gratitude to the Coors Brewing Company for making available a large and very complete data set for our use in developing this technical guidance document; and to the City of Palo Alto, Dept. of Public Works for permitting us to use the data they are collecting as part of a NPDES Permit Application. The Cadmus Group, Inc. and EA Engineering, Science and Technology, Inc also contributed to the success of this document.

Development of this document has been a collaborative effort between industry and the USEPA; it has been authored by Russell S. Kinerson, Ph. D. ( USEPA), Jack S. Mattice, Ph. D. ( EPRI), and James F. Stine ( UWAG). iv TABLE OF CONTENTS 1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 Considerations of Reasonable Potential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2. Margin of Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.3. Converting from Total Recoverable to Dissolved Criteria . . . . . . . . . . . . . . . . . . . . . . 2 1.4. Translating from a Dissolved Metal Ambient Water Quality Criterion to a Total Recoverable Concentration in the Effluent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.5. Developing Translators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.5.1. Direct Measurement of the Translator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.5.2. Calculating the Translator Using the Partition Coefficient . . . . . . . . . . . . . . . 6 1.5.3. The Translator as a Rebuttable Presumption . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.6. Applying Metals Translators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2. UNDERSTANDING THE METALS TRANSLATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.1. Sorption Desorption Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.2. The Partition Coefficient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.2.1. Developing Site Specific Partition Coefficients . . . . . . . . . . . . . . . . . . . . . . . 10 3. FIELD STUDY DESIGN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.1. Sampling Schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.1.1. Considerations of Appropriate Design Flow Conditions for Metals . . . . . . . . 12 3.1.2. Frequency and Duration of Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3.2. Sampling Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3.2.1. Collect Samples at or Beyond the Edge of the Mixing . . . . . . . . . . . . . . . . . 13 3.2.3. Collect Samples from Effluent and Ambient Water and Combine in the Laboratory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.3. Number of Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3.4 Parameters to Measure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 3.5. The Need for Caution in Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 4. DATA GENERATION AND ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.1. Analytical Data Verification and Validation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.2. Evaluation of Censored Data Sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.3 Calculating the Translator Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 5. SITE SPECIFIC STUDY PLAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 5.1. Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 5.2. Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 5.3. Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 5.4. Sampling Stations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 5.5. Sampling Schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 5.6. Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 5.7 Sampling Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 5.8. Field Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 5.9. Data Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 v 5.10. Schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 5.11. State Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 6. BUILDING A SPREADSHEET MODEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 7. REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 APPENDIX A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 APPENDIX B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 APPENDIX C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 APPENDIX D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 APPENDIX E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 APPENDIX F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 vi Executive Summary his guidance presents show a functional relationship to environmental Tprocedures that may be used to properties such as TSS, pH, and salinity, determine translator values that samples should be collected under an more accurately reflect site specific conditions. appropriate range of conditions in order to In this Executive Summary, steps to implement develop a statistically robust translator. If the the dissolved metals policy through translator is not to be functionally related to development and use of the translator are adsorbent concentrations, or other presented. environmental parameters, the study would Before beginning a translator study one low flow conditions where TSS concentrations should make a determination of reasonable are relatively constant. Either the directly potential with a translator of 1 ( all the metal in determined translator ( the ratio of C / C ) or a the effluent becomes dissolved in the receiving translator calculated by using a partition water). If the releases of metal from a coefficient ( K ) may be used. discharge do not pose a reasonable potential of exceeding water quality criteria levels with the The most direct procedure for largest possible translator, then a permit limit determining a site specific metal translator is does not have to be written for their release. simply to determine f by measuring C and C However, if a discharge has a water quality and to develop the dissolved fraction as the based permit limit for a metal, and the State is ratio C / C . The translator is calculated as the adopting standards based on dissolved metals, geometric mean of the dissolved fractions. then a translator study is needed.

In the toxicity tests to derive metal as a function of TSS and other factors such as criteria, some fraction of the metal was pH, salinity, etc. The partition coefficient is dissolved and some fraction was bound to the ratio of the particulate sorbed and dissolved particulate matter. Assuming that the dissolved metal species multiplied by the adsorbent fraction more closely approximates the concentration. Use of the partition coefficient biologically available fraction than does total may provide advantages over the dissolved recoverable, conversion factors have been fraction when using dynamic simulation for calculated. The conversion factors are Waste Load Allocation ( WLA) or the Total predictions of how different the criteria would Maximum Daily Load ( TMDL) calculations be if they had been based on measurements of and permit limit determinations because K the dissolved concentrations. allows for greater mechanistic representation of The translator is the fraction of total variables have on f . recoverable metal in the downstream water that is dissolved; f = C / C . It may be determined D D T directly by measurements of dissolved and total recoverable metal concentrations in water samples taken from the well mixed effluent and receiving water ( i. e., at or below the edge of the mixing zone). EPA encourages that site specific data be generated to develop site specific translators.

If the translator is being developed to normally be designed to collect samples under D T P D T D D T A partition coefficient may be derived P the effects that changing environmental D 1 1. INTRODUCTION he U. S. Environmental dissolved metal. EPA will also approve a State TProtection Agency ( EPA) risk management decision to adopt standards issued a policy memorandum based on total recoverable metal, if those on October 1, 1993, entitled Office of Water standards are otherwise approvable as a matter Policy and Technical Guidance on of law. Interpretation and Implementation of Aquatic Life Metals Criteria (" Metals Policy"). The The adoption of the Metals Policy did 1 Metals Policy states: not change the Agency's position that the It is now the policy of the Office of Water that under Section 304( a) of the Clean Water Act the use of dissolved metal to set and measure continue to be scientifically defensible. When compliance with water quality standards is the developing and adopting its own standards, a recommended approach, because dissolved State, in making its risk management decision, metal more closely approximates the may wish to consider sediment, food chain bioavailable fraction of metal in the water effects and other fate related issues and decide column than does total recoverable metal. to adopt total recoverable or dissolved metals The primary mechanism for toxicity to organisms that live in the water column is by Because EPA's Section 304( a) criteria adsorption to or uptake across the gills; this are expressed as total recoverable metal, to physiological process requires metal to be in a express the criteria as dissolved, application of dissolved form. This is not to say that a conversion factor is necessary to account for particulate metal is nontoxic, only that the particulate metal present in the laboratory particulate metal appears to exhibit toxicity tests used to develop the total substantially less toxicity than does dissolved recoverable criteria. metal. Dissolved metal is operationally defined as that which passes through a 0.45 µ m or a By regulation ( 40 CFR 122.45( c)), the 0.40 µ m filter and particulate metal is permit limit, in most instances, must be operationally defined as total recoverable metal expressed as total recoverable metal. Because minus dissolved metal. Even at that, a part of chemical differences between the discharged what is measured as dissolved is particulate effluent and the receiving water are expected to metal that is small enough to pass through the result in changes in the partitioning between filter, or that is adsorbed to or complexed with organic colloids and ligands. Some or all of this may be unavailable biologically.

The Metals Policy further states:

Until the scientific uncertainties are better resolved, a range of different risk management decisions can be justified. EPA recommends that State water quality standards be based on 2 existing total recoverable criteria published criteria.

3 The complete October 1, 1993 memorandum 1 can be obtained from EPA's Office of Water Resource metals in the effluent, in this case, would underestimate Center ( 202) 260 7786 or the Office of Water Docket. the impact on the receiving water. See Section 510, Federal Water Pollution 2 Control Act, Public Law 100 4, 33 U. S. C. 466 et seq.

For example, metals in the effluent of an 3 electroplating facility that adds lime and uses clarifiers will be a combination of solids not removed by the clarifiers and residual dissolved metals. When the effluent from the clarifiers, usually with a high pH level, mixes with receiving water with a significantly lower pH level, these solids instantly dissolve. Measuring dissolved 2 dissolved and adsorbed forms of metal, an uncertainties in establishing the TMDL and additional calculation using what is called a shall describe the manner in which the MOS is translator is required. This translator determined and incorporated into the TMDL. calculation answers the question " What fraction The MOS may be provided by leaving a portion of metal in the effluent will be dissolved in the of the loading capacity unallocated or by using receiving water body?" Translators are not conservative modeling assumptions to establish designed to consider bioaccumulation of WLAs and LAs. If a portion of the loading metals. capacity is left unallocated to provide a MOS,

1.1 Considerations of Reasonable Potential Water quality based permit limitations percentile translator value to address MOS are imposed when a discharge presents a needs and account for variabliity of data and to reasonable potential to cause or contribute to a use the critical 10 and 90 percentiles for violation of the applicable water quality other variables such as hardness and TSS when standard. . If the releases of metal from a conducting steady state modeling. facility are sufficiently low so as to pose no reasonable potential of exceeding water quality criteria levels, then a permit limit does not have to be written for their release. If a facility has a water quality based permit limit for a metal, and the State is adopting standards based on In the toxicity tests used to develop dissolved metals, then a translator is needed to metals criteria for aquatic life, some fraction of produce a permit limit expressed as total the metal is dissolved and some fraction is recoverable metal. Of course, if the facility has bound to particulate matter. When the toxicity a technology based permit limit for the metal tests were originally conducted, metal and the limit is more stringent than a limitation concentrations were expressed as total. Some necessary to meet water quality standards, then of the tests were repeated and some test no translator is required or appropriate. conditions were simulated, for the purpose of 1.2. Margin of Safety TMDLs must ensure attainment of than does total recoverable, these conversion applicable water quality standards, including all factors have the effect of reducing the water numeric and narrative criteria. TMDLs include quality criteria concentrations. The conversion waste load allocations ( WLAs) for point factors are predictions of how different the sources and load allocations ( LAs) for nonpoint criteria would be if they had been based on sources, including natural background, such measurements of the dissolved concentrations that the sum of these allocations is not greater in all of the toxicity tests that were most than the loading capacity of the water for the important in the derivation of the criteria. pollutant( s) addressed by the TMDL, minus the sum of a specified margin of safety ( MOS) and Consequently each metal's total any capacity reserved for future growth. The recoverable criterion must be multiplied by a MOS shall be sufficient to account for technical conversion factor to obtain a dissolved criterion the amount left unallocated shall be described. If conservative modeling assumptions are relied on to provide a MOS, the specific assumptions providing the MOS shall be identified. For example, a State may recommend using the 90 th th th 1.3. Converting from Total Recoverable to Dissolved Criteria determining the percent of total recoverable metal that is dissolved. Working from the premise that the dissolved fraction more closely approximates the biologically available fraction 3 that should not be exceeded in the water column. For example, the silver acute For additional details on aquatic life conversion factor of 0.85 is a weighted average criteria for metals, the reader is referred to FR and is used as a prediction of how much the 60( 86): 22229 22237. final acute value would change if dissolved had been measured. At a hardness of 100 mg/ L as calcium carbonate ( CaCO ) , the acute total 3 recoverable criterion is 4.06 µ g/ L while the dissolved silver criterion is 3.45 µ g/ L.

Both freshwater ( acute and chronic) and saltwater ( acute) conversion factors are 4 presented ( Tables 1 and 2); conversion factors for saltwater chronic criteria are not currently available. Where possible, these conversion factors are given to three decimal places as they are intermediate values in the calculation of dissolved criteria. Most freshwater aquatic life criteria are hardness dependent as are the 5 conversion factors for Cd and Pb. The values shown in these tables are with a hardness of 100 mg/ L. Conversion factors ( CF) for any hardness can be calculated using the following equations:

Cadmium Acute: CF = 1.136672  [ ln ( hardness) ( 0.041838)]

Chronic: CF = 1.101672  [ ln ( hardness) ( 0.041838)]

Lead Acute and Chronic: CF = 1.46203  [ ln( hardness) ( 0.145712)]

Federal Register / Vol. 60, No. 86 / 22229 4 22237 / Thursday, May 4, 1995 / Rules and Regulations. Water Quality Standards; Establishment of Numeric Criteria for Priority Toxic Pollutants; States' Compliance Revision of Metals Criteria.

Although most of the freshwater aquatic life 5 criteria for metals are hardness dependent, those for trivalent arsenic, trivalent chromium, mercury, aluminum, iron, and selenium are not. 4 Table 1. Freshwater Criteria Conversion Factors for Dissolved Metals Metal Conversion Factors Acute Chronic Arsenic 1.000 1.000 Cadmium 0.944 0.909 *

Chromium ( III) 0.316 0.860 Chromium ( VI) 0.982 0.962 Copper 0.960 0.960 Lead 0.791 0.791 *

Mercury 0.85 N/ A Nickel 0.998 0.997 Silver 0.85 N/ A Zinc 0.978 0.986 Conversion factors fro Cd and Pb are hardness dependent. The valuse show *

are with a hardness of 100 mg/ L as calcium carbonate ( CaCO ). 3 Table 2. Saltwater Criteria Conversion Factors for Dissolved Metals Metal Conversion Factors ( Acute)

Arsenic 1.000 Cadmium 0.994 Chromium ( III) N/ A Chromium ( IV) 0.993 Copper 0.83 Lead 0.951 Mercury 0.85 Nickel 0.990 Selenium 0.998 Silver 0.85 Zinc 0.946 The fractions of metals in dissolved and particulate phases are very dependent on water 5 chemistry. Because of the ( typically) great most straightforward approach is to analyze the differences between chemical properties of mixture to determine the dissolved and total effluents, the chemical properties of receiving recoverable metal fractions. This ratio of waters, and the chemical properties of the dissolved to total recoverable metal waters used in the toxicity tests, there is no concentrations can then be used to translate reason to expect that the conversion factors can from a dissolved concentration in the water be used to estimate either the fraction of metal column downstream of the effluent discharge that would be in the dissolved phase in the ( the criterion concentration) to the total receiving waters or the total recoverable metal recoverable metal concentration in the effluent concentration in the effluent that would result that will not exceed that dissolved in a receiving water concentration not concentration in the water column. exceeding a criterion concentration. Thus, a translator is required to derive a total Appendix A presents an example that recoverable permit limit from a dissolved summarizes the steps involved in applying the criterion . dissolved metals policy, using the translator, to 6 1.4. Translating from a Dissolved Metal Ambient Water Quality Criterion to 1.5. Developing Translators a Total Recoverable Concentration in the Effluent As the effluent mixes with the regarding development and application of the receiving water, the chemical properties of the metals translator to go from a dissolved metal mixture will determine the fraction of the metal criterion to a total recoverable permit limit. that is dissolved and the fraction of the metal This chapter identifies different approaches that that is in particulate form ( typically adsorbed to may be used in developing site specific surfaces of other compounds). Many different translators. In the following chapters, we will properties influence this dissolved to total focus on designing and conducting field studies, recoverable metal ratio. Important factors analytical chemistry procedures, data analysis, include water temperature, pH, hardness, and application of the metals translator to meet concentrations of metal binding sites such as mass balance requirements. concentrations of total suspended solids ( TSS), particulate organic carbon ( POC), and There is always a translator in going dissolved organic carbon ( DOC), as well as from a dissolved criterion to a total recoverable concentrations of other metals and organic permit limit. The rebuttable presumption is compounds that compete with the metal ions that the metal is dissolved to the same extent as for the binding sites. It is difficult to predict it was during criteria development. The default the result of such complex chemistry. The translator value should be that the translator develop a permit limit.

The purpose of this technical guidance document is to present additional details equals the conversion factor, this represents a reasonable worst case.

EPA encourages that site specific data be generated to develop site specific partition coefficients ( translators), and use of translators based on EPA's old data ( as published in USEPA, 1984 and presented in Table 3 below) As a reasonable worst case, however, it may be 6 assumed that metal in the receiving environment would be biologically available to the same extent as during toxicity testing; and the conversion factors may be used as translators if a site specific translator is not developed. In that case, the water quality criterion that already has been multiplied by the conversion factor would be divided by the conversion factor. 6 be phased out unless other data as suggested conservative estimates of the translator. below, have been generated that establish their Similar conclusions have been arrived at with validity for the sites in question. The guidance data from rivers and streams in Washington. released on October 1, 1993 identified three Therefore, it may be appropriate to develop a methods of estimating the metals translator. dissolved to total recoverable ratio based on a One of these was the use of the relationships single sample to confirm that the partition developed from the STORET data ( USEPA, coefficient produces an estimate of the 1984). In the years between 1984 and 1993 translator that is either reasonably accurate or there was general recognition that the conservative. relationships had some inaccuracies due to contaminated metals data and other factors. This guidance document presents However, limited comparisons of predictions procedures that may be used to determine from these relationships with data generated translator values that accurately reflect site and analyzed with good QA/ QC indicated specific conditions. generally good agreement and some tendency to be conservative. The stream data for lead The procedures in this document do not were reanalyzed and a better relationship was cover all possible approaches. Greater developed. The parameters for these default precision can be achieved by means of more partition coefficient estimation equations are elaborate procedures which, at the current time, presented in Table 3 where K has units of L/ kg are generally used only in research situations. P with TSS expressed as mg/ L. Although, the use of such procedures is Table 3. Calculation of Default Partition document. Coefficients [ K = K ° TSS ] P PO Lakes Streams Metal K K PO PO Cu 2.85E+ 06  0.9000 1.04E+ 06  0.7436 Zn 3.34E+ 06  0.6788 1.25E+ 06  0.7038 dissolved water quality criterion to a total Pb 2.0E+ 06  0.5337 2.80E+ 06  0.8 Cr( III 2.17E+ 06  0.2662 3.36E+ 06  0.9304 fractions. The translator is the fraction of total )

Cd 3.52E+ 06  0.9246 4.00E+ 06  1.1307 Ni 2.21E+ 06  0.7578 4.90E+ 05  0.5719 Site specific conditions may render these default partition coefficients, overly or underly protective. Data presented in Appendix B illustrate the variability that exists between different sites in some values of the dissolved metal fractions. Recent work by Sung ( 1995) demonstrates that reliance on the relationships in Table 3 does not always provide for 7 acceptable, they will not be discussed in this 1.5.1. Direct Measurement of the Translator As mentioned in Section 1.4, the most straightforward approach for translating from a recoverable effluent concentration is to analyze directly the dissolved and total recoverable recoverable metal that is dissolved and may be determined directly by measurements of dissolved and total recoverable metal concentrations in water samples.

1.5.2. Calculating the Translator Using the Partition Coefficient Personal communication with Gregory 7 Pelletier, Department of Ecology, Olympia, WA ( 206) 407 6485. 7 The partition coefficient ( K ) may be options are unavailable. There are some P derived as a function of the number of metal advantages to its use including the fact that it is binding sites associated with the adsorbent. already being used by some States, it is easy to USEPA ( 1984) and the technical support explain and implement, and it effectively accompanying EPA's Dissolved Policy implements the statutory requirement found in Memorandum expressed the translator § 303( d) of the Clean Water Act calling for a according to Eqn 2.7. The role of TSS is margin of safety ( MOS) in developing TMDLs. evident from this equation; as TSS increases, The disadvantage is that, as demonstrated by the dissolved fraction decreases because of the the conversion factors used to convert total increased number of binding sites. recoverable water quality criteria into the There is a general tendency to assume will remain totally in the dissolved form, even that the partition coefficient will increase with in high quality water. Furthermore, when the increasing TSS. It is important to recognize assumption that all of the metal is dissolved is that in both the laboratory and in the field, K applied in combination with dissolved criteria P has been observed to be constant or to decrease conversion factors, the resulting permit limit is with increasing particulate concentrations ( Di more restrictive than that which existed when Toro, 1985). metal criteria were expressed as total The fraction of the total metal in the presumption, conversion factors can be used as downstream water that is dissolved ( the the translator where no site specific translator translator) may be determined indirectly by is developed; this is the reasonable worst case . means of a partition coefficient. The partition coefficient, in turn, may be either a function of varying adsorbent concentrations or be related to a constant adsorbent concentration associated with critical flow conditions. See Section 3.1.1 for considerations of factors affecting the If the translator is to be a function of appropriate design flow for metals. adsorbent concentrations ( e. g., TSS) it is critical 1.5.3. The Translator as a Rebuttable Presumption In the Technical Support Document for samples under low flow conditions where TSS Water Quality based Toxics Control ( EPA, concentrations are relatively constant. Either 1991a) commonly called the TSD, as well as in the directly determined ratio ( C / C ) or a other documents, EPA has discussed the translator calculated using a partition options one has for translators. These options coefficient ( K ) may be used. include using a translator which assumes no difference between dissolved and total In actuality, metal partitioning in recoverable metal concentrations. The TSD receiving water bodies is more complicated identifies this as the most stringent approach and suggests it would be appropriate in waters with low solids concentrations, situations where the discharged form of the metal was mostly in the dissolved phase, or where data to use other dissolved form, it is highly unlikely that metals recoverable. Therefore, as a rebuttable 8 1.6. Applying Metals Translators that samples be collected under a broad range of TSS conditions to develop a statistically robust translator. If the translator is not to be functionally related to adsorbent concentrations the study would normally be designed to collect D T P Using the conversion factors as a translator will 8 produce the same result as assuming no difference between dissolved and total recoverable metal concentrations. 8 than can be explained by TSS alone. Consequently, it is possible and permissible to develop the translator on some basis other than TSS, such as humic substances or POC. The 9 materials presented in Appendix C guide the reader through a possible evaluation of other factors that might be warranted in some studies.

Basically, the translator is applied by dividing a dissolved WLA or permit limitation by the translator to produce a total recoverable permit limitation. Appendix A contains a detailed explanation of how permit limits can be derived.

If the adsorbent is POC, then K ( L/ mg) = C 9 P P ( µ g/ L ) / ( C ( µ g/ L) ° POC ( mg/ L) D 9 2. UNDERSTANDING THE METALS TRANSLATOR he translator is the fraction of Tthe total recoverable metal in The metal concentrations are typically the downstream water that is expressed as mass per volume ( i. e., C dissolved. The reason for using a metal ( mass/ vol water), C ( mass/ vol solids plus translator is to allow calculation of a total water, the bulk volume)). recoverable permit limit from a dissolved criterion. For a given adsorbent concentration A translator is used to estimate the concentration of total recoverable metal in the C = x ° m [ Eqn 2.2] effluent discharge that equates to ( or results in) the criterion concentration in the receiving where x is the metal concentration of the water body. In this chapter we will explore particulate phase expressed on a dry weight some of the possible approaches to developing solids basis ( e. g., µ g/ mg) and m is the site specific metals translators. The purpose of adsorbent concentration ( mass of solids/ vol of this document is to help implement EPA's solids and water; e. g., mg/ L). With these dissolved metals policy; therefore, every dimensions, C has units of µ g/ L. attempt has been made to keep the following discussion as technically simple as possible. As you read this discussion, keep in mind that the metals partition between dissolved and adsorbed forms. The partition coefficient expresses this equilibrium relationship and may The distribution of metal at equilibrium be used to calculate the dissolved fraction. The between the particulate and dissolved forms is following discussion presents only the essential the partition coefficient K ( L/ mg). The equations needed to develop the translator. For partition coefficient is the slope of the data of a comprehensive discussion of partition particulate metal ( µ g/ mg) against dissolved coefficients, see Thomann and Mueller ( 1987). metal ( µ g/ L)

2.1. Sorption Desorption Theory In effluents and receiving waters, provides other useful relationships between metals can exist in either of two basic phases; dissolved and particulate metals concentrations adsorbed to particulates or dissolved in water. More precisely, these " particulates" are C = C ° K ° m [ Eqn 2.4] sorbents including clays and related minerals, humic substances, organic and inorganic ligands, and iron and sulfur compounds. The Substituting Eqn 2.4 into Eqn. 2.1 gives total concentration of a metal in the water column can be expressed as C = C + C [ Eqn 2.1] C = ( C ° K ° m) + C T P D where C = total metal, T C = particulate sorbed metal, and P C = dissolved metal. D D P ( e. g., TSS) C can be expressed as P P P 2.2. The Partition Coefficient and the Dissolved Fraction P K = x / C [ Eqn. 2.3] P D Combining Eqn. 2.3 with Eqn 2.2 P D P C = C + C T P D T D P D 10 C = C ( K ° m + 1) [ Eqn 2.5] dissolved metal ( C ). T D P The translator, or dissolved metal fraction, f , K = x / C D is defined as f = C / C [ Eqn. 2.6] let m = TSS, then x = C / TSS. D D T Substituting Eqn 2.6 into Eqn 2.5 and solving for f gives D f = ( 1 + K ° m) [ Eqn. 2.7] D P  1 The distribution of metal between dissolved and adsorbed phases therefore depends on the K = C / ( C ° TSS ) [ Eqn. 2.9] partition coefficient and the adsorbent concentration. This is the basis of the metals translator.

2.2.1. Developing Site Specific Partition Coefficients As we saw in Eqn. 2.3, the partition coefficient is not measured directly, rather it is calculated from measured values ( at equilibrium) of adsorbed metal per unit adsorbent ( x) divided by the concentration of 10 D P D We also saw in Eqn. 2.2 that C = x ° m. If we P P Substituting into Eqn 2.3 gives K = ( C / TSS ) / C [ Eqn. 2.8] P P D which rearranges to 11 P P D TSS is used throughout this document as the 10 measure of metal binding sites. It is possible to use other measures of the binding sites such as total organic carbon ( TOC), particulate organic carbon ( POC), dissolved modified by the conversion factor of 10 kg/ mg: organic carbon ( DOC), or some combination of TSS, TOC, K ( L/ kg) = C ( µ g/ L ) / ( C ( µ g/ L) ° TSS ( mg/ L) DOC, etc. ° 10 ( kg/ mg)) If K is desired with units of L/ kg, Eqn 2.9 is 11 P  6 P P D  6 11 3. FIELD STUDY DESIGN onsideration should be given to in the watershed, photosynthetic activity in the Cuse of clean sampling and water body ( lowest pH at dawn and highest pH analytical techniques. These in early afternoon coincident with peak are recommended but not necessarily required; photosynthetic activity of phytoplankton and however, it is essential that appropriate other aquatic vegetation), or effluent discharge procedures be used to detect metals at the to the water body. Changes in pH over a concentrations present in the effluent and specific range may have a marked effect on receiving waters. Clean sampling and metal solubility. Consequently, it may be analytical methods are useful ways of obtaining important to consider the normal range of pH good data when traditional methods may when designing the study and to collect provide data with significantly high or low bias. samples under pH conditions that would render Sufficient quality control data must accompany the metal or metals of interest most soluble, or environmental data to allow its validation. over a narrow range of pH conditions to reduce 12 A statistically valid field study design, is of concern in geographic areas that have little with attendant QA/ QC, ( e. g., adequate number buffering capacity and on " acid sensitive" of samples, field blanks, spiked samples, etc.) streams. is essential for the successful development of a metals translator. Recognizing that a key factor Industrial and municipal waste waters in metals availability to biota in the water and receiving waters vary greatly in chemical column is the partitioning of metals between constituents and characteristics. This chapter the solid phase material and water, TSS ( which presents general guidelines and considerations contains humic materials, clay minerals, other to assist in establishing effective sampling organic matter both living and dead) emerges programs for varied situations. as the obvious environmental variable of interest. However, the composition of TSS is highly variable both in terms of the constituents ( e. g., sand, silt, clay, planktonic organisms, and decomposing organic materials) and their size The sampling design should be distributions. Highly variable relationships adequate to evaluate spatial and/ or temporal between TSS and metals partitioning must be variability and to properly characterize the anticipated because of the temporal ( e. g., environmental condition. The choice of when season of year, type and magnitude of storm) and where to conduct the study, how long to and the spatial variability ( e. g., such as may be study, and how frequently to sample may be associated with changes in hydrology, influenced by the type of translator being geochemistry, or presence, number, and type of developed. effluent dischargers) of the receiving water bodies. For example, pH may vary over several units as a result of acidic precipitation scatter in the resulting data set. The pH effect 3.1. Sampling Schedule For instance, the translator may be developed specifically for use under conditions that are most likely to be representative of " critical flow" or " design" conditions. ( The critical flow may or may not be the same as the 7Q10 or 4B3 design low flow; this is discussed in Section 3.1.1 below.) To meet this application, samples should be collected under Measurements made below the quantitation 12 levels ( QL) will suffer from significant analytical variability, which may directly affect the ratio ( especially if the ratio in near 1.0). Test measurements capable of achieving extremely low detection levels and QLs should be sought to avoid the excessive analytical variability. The choice of laboratories and analytical methods can be critical to the success of a translator study. 12 conditions that approximate the critical flow. For instance, consider a facility that has On the other hand, the translator may fraction of the receiving water flow. It may be be developed for use over a broad range of flow that TSS concentrations in the mixing zone and associated TSS concentrations. If this is show a bimodal distribution with stream flow desired, then the samples should be collected to ( high under low flow conditions because of the produce a data set representative of a broad effluent dominance, low under higher stream range of conditions. flow conditions because of greater dilution, and 3.1.1. Considerations of Appropriate Design Flow Conditions for Metals In the absence of data to the contrary, Additionally, pH may vary throughout the day, the normal assumption will be that low flow may vary seasonally, or may be somehow ( limited dilution capacity) is the critical flow correlated with flow. Information of this nature for metals. However, determining the period should also be used in selecting the most 13 of critical flow is more complicated for metals appropriate conditions and most appropriate than for many other pollutants because one time to conduct the study. To reduce cannot necessarily ascertain the appropriate variability in the data caused by factors other design conditions without a field study to than adsorbent concentration, it will be helpful generate data on flow, pH, and adsorbent to measure pH and, to the extent possible, concentrations. If one were to collect samples collect samples under similar pH conditions. of TSS, POC, water flow, hardness pH, As suggested above, samples should be ambient metals, etc. over a prolonged period collected under pH conditions that would ( i. e., several years) then one could examine the render the metal( s) of interest most soluble. data set to determine which combination of conditions would result in the highest dissolved metal concentration for a " unit load" of metal in the effluent stream. The flow regime associated with this critical condition would A field study to develop a metals constitute the design flow. Because the translator is expected to extend over several dissolved metals concentration in the receiving months. A long sampling schedule has many water depends on metals partitioning to solids advantages, chief among them is the ability to as well as dilution of dissolved metals in the generate data that are representative of the water, and because the lowest TSS ( or other many conditions that characterize receiving adsorbent) concentrations do not always water bodies. Ideally, prior to collecting data correspond with low stream flow conditions, to develop a metals translator, the receiving there will be some combination of TSS, flow, water body would have been studied hardness and pH that will result in the greatest sufficiently to characterize temporally, if not dissolved concentration. spatially, distributions of flow, TSS, hardness, high solids releases and contributes a sizeable high under high flow conditions because of upstream nonpoint source solids loadings). It is conceivable that the low TSS may be more important than low flow in achieving water quality standards in this stream segment.

3.1.2. Frequency and Duration of Sampling and pH. To the extent that such data exist, the sampling can be stratified to reduce variability. If such data are available to characterize the system, statistical methods may be used to determine the frequency of sampling. In the absence of such data, EPA suggests weekly or It is important to recognize that worse case 13 acute dilution ( highest concentration of effluent) may not occur during periods of low flow and TSS, especially in estuarine waters. Under such circumstances, the data to develop the translator should be collected to represent the critical conditions. 13 biweekly sampling during specified receiving zone, the CMC applies at the end of the pipe. water flow conditions when developing the The criteria chronic concentration ( CCC) translator for use under " design flow" applies at all points outside the CCC mixing conditions and biweekly or monthly sampling zone. when developing the translator for use over a range of flow conditions. There are some practical difficulties In addition to receiving water the receiving environment. In the absence of a conditions, it is equally important to consider mixing zone study it is very difficult to define variable plant operations when determining with any certainty the shape and extent of a sampling frequency. In addition to continuous mixing zone, or the dilution and dispersion that and uniform releases, the range of conditions occur within the mixing zone. Many states may include: have separate boundaries for compliance with ( 1) Seasonal operation, dispersion processes are influenced not only by ( 2) Less than 24 hour per day volume, velocity, and other characteristics of operation, the discharge, but also by convection, currents, ( 3) Special times during the day, week and wind effects in the receiving water. As a or month, or result, extensive sampling and computer ( 4) Any combination of the above. modeling are typically required to estimate the When monitoring these types of operations, it is necessary to sample during The following approaches are normal working shifts in the season of acceptable for the purpose of developing the productive operations. translator. When deciding where to locate 3.2. Sampling Locations Depending on state guidance or constitute a basis for concern that downstream regulatory negotiations, samples may be conditions may result in nontoxic metal collected from the effluent, the receiving water becoming toxic. before mixing with the effluent, the receiving water at the edge of the mixing zone, and/ or the receiving water in the far field ( beyond the mixing zone). Results obtained from these different locations may differ substantially.

The magnitude of the translator may collected at or beyond the edge of the mixing depend on the concentration of effluent in the zone. Appropriate field sampling techniques downstream water. The concentration of and appropriate QA/ QC are discussed in effluent in the downstream water will depend Appendix E. It is important to recognize that if on where the sample is taken, which will not be samples are not also collected from the ambient the same for acute and chronic mixing zones. water ( background), then the subsequent The criteria maximum concentration ( CMC) analysis ( for permit limit determination) applies at all points except those inside a CMC implicitly assumes that all of the metal in the mixing zone; thus if there is no CMC mixing receiving water comes from the discharger. involved in selecting the sampling location in acute and chronic criteria. Dilution and nature and extent of mixing.

sampling stations, consideration should be given to sampling at the point of complete mixing ( rather than at the edge of the mixing zone) if existing environmental factors 3.2.1. Collect Samples at or Beyond the Edge of the Mixing Zone It is recommended that samples be 14 The translator should result in a permit concentrations and increased analytical limit that is protective of the receiving water. difficulties must also be considered when In order to ensure this, under some conditions, contemplating these studies. If, however, the it may be important that samples be collected samples are collected within the same reach, from a point where complete mixing has there should not be any appreciable increase in occurred. It may be advisable within a given dilution. river segment to take the samples well below the edge of the mixing zone in order to ensure If samples for translators are collected good mixing and to reduce variability in the from far field locations a translator will result data set. Environmental processes that might whose value is established based on the cause nontoxic metal to become toxic include characteristics of the receiving water, not on fate processes such as oxidation of organic the characteristics at the edge of the mixing matter or sulfides or an effluent or tributary that zone or on the characteristics of the effluent lowers the pH of the downstream water. The before it is fully mixed. Recent investigations approach of collecting samples beyond the edge of discharges from a Waste Water Treatment of the mixing zone may be especially valuable Plant ( WWTP) to a lowflow stream in Florida in estuarine and coastal ocean locations where have demonstrated an apparent increase in the the ebb and flow of tidal cycles complicate the dissolved fraction of silver at a distance ( travel hydrodynamics. In areas where cumulative time) of four hours downstream of the 14 discharge effects can be anticipated, the discharge. individual contributions and combined effects of the multiple discharges must be considered in developing the translator, as well as in the TMDL allocation and development of the permit limit.

3.2.2. Collect Samples from the Far Field There are times when concerns for far water ( i. e., upstream of the outfall in rivers and field effects will require evaluation of the ratios streams; outside of the influence of the of dissolved and total recoverable metals and discharge in lakes, reservoirs, estuaries, and metal partitioning beyond the mixing zone. Far oceans). Appropriate QA/ QC and field field sampling is appropriate in circumstances sampling techniques are discussed in Appendix where changes in geology, land use/ land cover, E. Mixing and filtration must be done as soon or low pH effluent discharges from other as possible to minimize risk of changes to the facilities may alter the water body chemistry. dissolved/ total metals ratio due to adsorption Far field studies also may be required where onto the container and partitioning effects. The spatial changes in water chemistry and Agency is soliciting data that will allow hydrology affect sorption desorption rates and recommendations to be developed regarding settling rates respectively with the potential maximum delays in combining the samples and adverse effects on the biological integrity of how long the combined sample should be benthic communities. The potential for allowed to equilibrate before filtering an aliquot increased dilution resulting in lower metal for the dissolved portion. 15 3.2.3. Collect Samples from Effluent and Ambient Water and Combine in the Laboratory Samples are collected from the effluent ( i. e., end of pipe) and the ambient receiving This document does not discuss hydrologic Personal communication with Tim Fitzpatrick, 14 differences that are specific to marine and estuarine Florida Department of Environmental Protection, discharges. Tallahassee, FL. 15 15 Samples are collected from the effluent a theoretical minimum number of samples. and the receiving water before it mixes with the Beyond this consideration, it is necessary to be discharge and are mixed in accordance with the cognizant of such factors as spatial and dilution factor to create a simulated temporal variability in physical and chemical downstream water in proportion to the dilution conditions that may affect the value of the that the mixing zone is designed to achieve. translator and to design the study to The mixed waters are analyzed for dissolved appropriately account for these differences. and total recoverable metal. The translator is Seasonality of receiving water flow and calculated from the dissolved fractions. associated chemical properties need to be For rivers and streams, the receiving appropriate to provide protection to the water water samples would be collected upstream of body during the low flow or otherwise critical the discharge. For lakes, reservoirs, estuaries, condition associated with a particular critical and oceans, the samples would be collected at a time of the year. point beyond the influence of the discharge, yet representative of water that will mix with the In the metals guidance memorandum discharge. In tidal situations, where the ( Prothro, 1993), EPA recommended the effluent plume may move in different development of site specific chemical directions over the tidal cycle, some knowledge translators based on the determination of of the hydrodynamics of the receiving water dissolved to total ratios: EPA's initial will be necessary to select the appropriate point recommendation was that at least four pairs of as well as the appropriate sampling time within total recoverable and dissolved ambient metal the tidal cycle. In estuaries that are dominated measurements be made during low flow by either river flow or tidal flushing, the conditions or 20 pairs over all flow conditions. sampling location should reflect the dominant EPA suggested that the average of data source of dilution water. collected during low flow or the 95th percentile In cases of multiple discharges to the The low flow average provides a representative same river segment, for example, the translator picture of conditions during the rare low flow should be developed as f at the downstream events. The 95th percentile highest dissolved D end of the river segment and applied to all fraction for all flows provides a critical dischargers to that segment condition approach roughly analogous to the 3.3. Number of Samples The collection of dissolved and total Most statistics textbooks ( e. g., concentrations at low flows is still the Snedecor, 1956; Steel and Torrie, 1980; Zar, recommended approach, but the collection of at 1984; Gilbert, 1987)) present discussions of least 10 samples, rather than 4, is sample size ( i. e., number of samples). recommended to achieve higher confidence in Generally, sample size is affected by the the data. The 95 percentile or other extreme variance of the data, the allowable error in the percentile of f ( e. g., 90 percentile) may be estimation of the mean, and the desired used as an alternative method of including a confidence level. If data have been collected MOS in TMLDs or WLAs. Additional details previously, they can be used to provide a good of determining the required sample size are estimate of the expected variance. presented in Appendix D. From a statistical basis we can specify considered. The value of the translator must be highest dissolved fraction for all flows be used.

approach used to identify low flows and other critical environmental conditions.

th D th 16 3.4 Parameters to Measure Ideally the field study is designed to and ( 2) that new guidance is needed for generate data on total recoverable ( C ), sampling and analysis that will produce reliable T dissolved ( C ), and particulate metal fractions results for trace metals determinations. D ( C ) as well as TSS, POC, pH, hardness, and P stream ( volume) flow. A complete data set EPA has released guidance for allows for more complete understanding of the sampling in the form of Method 1669 environmental fate and transport processes and " Sampling Ambient Water for Determination may result in a more accurate permit limit of Trace Metals at EPA Water Quality Criteria because of reduced variability and Levels" ( USEPA, 1995a). This sampling uncertainties. method describes the apparatus, techniques, and Depending on the means by which the quality control necessary to assure reliable translator is being developed, some of these sampling. Method 1669 was developed based data elements may not need to be generated. on information from the U. S. Geological For instance, it may be desirable to estimate Survey and researchers in academia, marine C = C  C rather than to measure C . Of laboratories, and the commercial laboratory P T D P course, if C is the parameter of greatest community. A summary of salient points are P interest, calculating C from the dissolved and presented in Appendix E. Interested readers P total recoverable concentrations incorporates may also wish to refer to the 1600 series of the uncertainty associated with the latter two methods, CFR 40, Part 136, July 1, 1995. measurements. A direct measurement of the particulate fraction may reduce this uncertainty. Note that recent studies conducted by Of course, the measurement of the particulate the USGS ( Horowitz, 1996) indicate that great fraction then increases the total uncertainty bias can be introduced into dissolved metals because of the uncertainty associated with its determinations by filtration artifacts. The use measurement. It is likely that if the three of the Gelman # 12175 capsule filter, which has fractions ( total, dissolved, and particulate) are an effective filtration area of 600 cm , and the measured, the sum of these three fractions will practice of limiting the volume of sample not equal C . It is possible to develop the passed through the filter to 1000 ml are T translator from a study that only generates data necessary to ensure unbiased collection of on total recoverable and dissolved dissolved metals. Variations from these concentrations in the downstream water. recommendations must be demonstrated to 3.5. The Need for Caution in Sampling The sampling procedures for metals that have been used routinely over the years have recently come into question in the academic and regulatory communities because the concentrations of metals that have been entered in some databases have been shown to be the result of contamination. At EPA's Annapolis Metals Conference in January of 1993, the consensus of opinion was ( 1) that many of the historical low concentration ambient metals data are unreliable because of contamination during sampling and/ or analysis,

2 produce equivalent quality data. 17 4. DATA GENERATION AND ANALYSIS etermination of metals' reported by laboratories and permittees Dconcentrations at ambient so that Agency reviewers can validate criteria levels is not presently the data. routine in many commercial and industrial laboratories. To familiarize laboratories with The review of data collected and the equipment and techniques that will allow reported in accordance with data determination of metals at trace levels, the elements reported. Agency has supplemented existing analytical methods for determination of metals at these A Data Inspection Checklist that can be levels, and published this information in the used to standardize procedures for " Quality Control Supplement for Determination documenting the findings of each data of Trace Metals at EPA Water Quality Criteria inspection. Levels Using EPA Metals Methods" ( QC Supplement; USEPA, 1994a). The QC Supplement is based on the procedures and techniques used by researchers in marine research laboratories who have been at the Frequently data sets are generated that forefront of trace metals determinations. contain values that are lower than limits An overview of the QC Supplement is values ( i. e., quantitation levels [ QL]). These presented in Appendix E for the reader's data points are often reported as nondetected convenience. Persons actually developing a and are referred to as censored. The level of metal translator should read the QC censoring is based on the confidence with Supplement which the analytical signal can be discerned 4.1. Analytical Data Verification and Validation In addition to Method 1669 for Measurements made below the sampling ( USEPA, 1995a) and analytical quantitation levels will suffer from analytical methods for determination of trace metals variability, which may directly effect the ratio, ( USEPA, 1994b), the Agency has produced especially if C / C is near 1.0. Extremely low guidance for verification and validation of detection levels and quantitation levels should analytical data received ( USEPA, 1995b). This be sought to avoid excessive analytical guidance was produced in response to the variability. Agency's need to prevent unreliable trace metals data from entering Agency databases This guidance does not address whether and other databases in the environmental or not it is appropriate to use test measurements community and relies on established techniques below quantitation or detection levels in any from the Agency's data gathering in its Water context other than chemical translator studies and Superfund analytical programs to conducted by the discharger. For translator rigorously assess and document the quality of studies, measurements at or above a detection analytical data. General issues covered in the level that is reliably achievable by the guidance include:

The data elements that must be 4.2. Evaluation of Censored Data Sets deemed reliable enough to report as numerical from the noise. While the concentration may be highly uncertain for substances below the reporting limit, it does not necessarily mean that the concentration is zero ( USEPA, 1992).

D T 18 Box 1. The Translator is the Dissolved Fraction: f = C / C D D T Step 1  For each field sample determine f = C / C D D T Step 2  If the translator is not dependent on TSS, determine the geometric mean GM_ f = exp( ln( f )/ n) D 1 D n and upper percentile values of the dissolved fraction. If the data are found not to be log normal, then alternative transformations should be considered to normalize the data and determine the transformed mean and percentiles. Also, alternative upper percentiles may be adopted as a state's policy to address MOS ( e. g., 90 or 95 th th percentiles may be appropriate.)

Step 3  If the translator is found to be dependent on TSS, regression equations relating f to TSS should D be developed. Appropriate transformations should be used to meet the normality assumptions for regression analysis ( for example log transformation of f D and TSS may be appropriate). The regression equation or an upper prediction interval may be considered for estimation of f D from TSS depending on the strategy for addressing MOS. particular laboratory performing the analyses can be used. If concentrations are near the detection level, some of the samples may be reported as below the detection level ( i. e., nondetects). If both total recoverable and dissolved concentrations are nondetects, the data pair should be discarded. If only the dissolved concentration is nondetect, it could be assumed to equal one half the detection level. Some studies have collected enough data so that incomplete records, including records where dissolved concentrations were nondetects, were discarded prior to analysis. If, for example, the translator is a function of TSS, the TSS concentration that accompanies each total recoverable and dissolved data pair must also be at or above the detection level. Alternatively, assuming that an adequate number of samples have been collected, incomplete records may be eliminated from analysis.

4.3 Calculating the Translator Value The most direct procedure for determining a site specific metal translator is simply to determine f by measuring C and C D T D and to develop the dissolved fraction as the ratio C / C . The first step ( Box 1) is to D T calculate the dissolved fraction in the receiving water. The translator is calculated as the geometric mean of the dissolved fractions.

As a general comment on the proposed use of the geometric mean, the geometric mean is only an appropriate estimate of the central tendency if the data are log normal. Alternative measures of central tendency or transformations should be considered if the distribution of f is found not to be log normal. D For example, the arcsine square root transformation is often used to normalize populations of percentages or proportions 19 Box 2. The Translator is the Dissolved Fraction ( f ) D Calculated via Site Specific Partition Coefficients Step 1  For each field sample determine C = C  C , P T D K = C /( C ° TSS) P P D Step 2  Fit least squares regressions to data ( transformed, stratified by pH, etc.) as appropriate to solve for K . P Step 3  Substitute the regression derived value of K in Eqn 2.7, P f = ( 1 + K ° TSS) D P  1 Step 4 Determine f for a TSS value D representative of critical conditions. ( square root of each value is transformed to its have on f . arcsine).

A partition coefficient may be derived determine appropriate translator values are as a function of TSS and other factors such as presented in Appendix C. pH, salinity, etc. ( Box 2). The partition coefficient is the ratio of the particulate sorbed and dissolved metal species multiplied by the adsorbent concentration. The dissolved fraction and the partition coefficient are related as shown in step 3.

The partition coefficient may provide advantages over the dissolved fraction when using dynamic simulation for Waste Load Allocation ( WLA) or the Total Maximum Daily Load ( TMDL) calculations and permit limit determinations because K allows for P greater mechanistic representation of the effects that changing environmental variables D Examples of these analyses to 20 5. SITE SPECIFIC STUDY PLAN hapter 3 discusses the to any type of receiving water. Where Cconsiderations involved in differences in the study plan would occur for designing a field study for a different receiving waters, the considerations site specific chemical translator for metals. are highlighted with a . Dischargers on run Chapter 4 and Appendix D discuss analytical of river reservoirs, or on lakes or reservoirs chemistry considerations. This Chapter dominated by riverain discharges during runoff provides guidance on preparing a basic study events, should generally follow the plan for implementing a translator study, with considerations listed for rivers/ streams. specific considerations for each of four types of receiving waters: rivers or streams, lakes or reservoirs, estuaries, and oceans. It can be used for all of the options discussed in this guidance. This generic plan is based on the determination State the objective of the project. For of dissolved to total ratios in a series of 10 or example, more samples. With this guidance, the discharger should be able to prepare a study " To determine the acute [ or plan that its environmental staff could chronic or acute and chronic] implement or one that could be used to solicit metals translator for [ list bids from outside consultants to conduct the metals] in the discharge from studies. In most cases, the study plan should be Outfall 00X." submitted to the state for review and approval before implementation.

The format of this chapter is to present sequentially the essential sections of a study Describe briefly the approach adopted plan: objective, approach, parameters, in the study plan to achieve the objective. For sampling stations, sampling schedule, example, preparation, sampling procedure, field protocol, and data analysis. Within each section a three " Samples of effluent and tiered format is used to provide instructions for upstream receiving water will the study plan preparer. The basic directions be collected and mixed in for preparing the section are presented left proportions appropriate to the justified on the page. Under each direction is a dilution at the edge of the checklist of decisions or selections, designated [ acute/ chronic] mixing zone[ s]. with the symbol , that the preparer must make These mixed samples will be to complete that direction. Under each of these analyzed for total recoverable decision points is a list of important and dissolved [ list metals]. The considerations, noted by the symbol . translator will be calculated as References to more detailed discussions are the geometric mean of the provided where appropriate. If any state ratios of dissolved metal to guidance for translator studies exists, it would total recoverable metal for all supersede any of the considerations discussed sample pairs." below unless the state and the discharger agree to an alternative plan. Equipment blanks and field blanks are Much of the basic study plan is presented in a generic context that is applicable 5.1. Objective 5.2. Approach critical to document sample quality, 21 especially at low concentrations which can be be necessary to achieve detection levels significantly biased by even small amounts of low enough to produce a valid contaminants. Field duplicate samples are also translator. Such alternatives include very important to establish precision in matrix modifiers, backgroundsampling and final sample preparation. correction instrumentation, and 5.3. Parameters analyses. Preliminary testing and Prepare a table listing parameters, detection level studies may be analytical methods, and required detection necessary to determine if a problem levels. exists.

Select parameters   see Section 3.4. As an option for justifying the selected Select analytical methods and detection agency, prepare a narrative of the rationale for levels   see Section 4. the selections made.

Detection level will be the primary Identify the laboratory that will be determinant of the analytical methods analyzing the samples and provide evidence of to be used. Metals potentially requiring state certification, if required. GFAA and perhaps ultralow analyses are those with very low aquatic life Describe laboratory protocols and QA criteria and concentrations below 10 requirements. g/ L. Prime candidates are cadmium ( fresh water), copper ( salt water), Select standard or clean ( class 100) mercury, and silver. practices   see Section 3.1, 4.3.

Ideally, the detection level should be 5 Select QA requirements 10 times lower than the concentration of dissolved metal. An ultralow Trip blank detection level should be considered if Duplicate analysis of all samples and dissolved concentrations are less than blanks 1 2 times higher than the standard Laboratory method blank for each detection level. batch of samples Detection levels and methods should be reviewed with the analytical laboratory expected to perform the analyses before finalizing the study plan. One or more test samples may be advisable if Prepare a map and/ or a narrative detection levels or concentrations are description of the sampling stations. unknown in any particular matrix.

Estuary/ Ocean Chloride interference may affect detection levels, particularly for GFAA methods. Special steps may extraction or preconcentration. If uncertain, check with a local laboratory experienced in saltwater matrix methods and detection levels to the regulatory MS/ MSD on each batch of samples 5.4. Sampling Stations Select a sample location option   see Sections 3.2, 3.2.1, 3.2.2, 3.2.3.

Conceptually, collecting samples at the 22 edge of the mixing zone is the Determine whether grab or composite most direct way to determine samples will be used   see Appendix the translator. However, the E. edge of the mixing zone may be difficult to define, especially Wastewater treatment plant if stream flow and discharge effluent   24 hour composite rate ( e. g., number of units Noncontact cooling water   same as operating) will be variable over receiving water the course of the study. Even if the mixing zone's dimensions are prescribed exactly, the samples may have to be collected at some critical hydrologic condition to represent the critical toxicological conditions. An alternative option may be to collect effluent and upstream receiving water samples, and mix them in the appropriate proportions before analysis. In addition, far field sampling may be required to establish that dissolved metal concentrations do not increase after the effluent is well mixed with the receiving water.

Definition of the " upstream" sampling point will vary with the receiving water type:

River/ Stream Immediately upstream of the influence of the discharge, or any point further upstream with no contributing source between it and the outfall Lake/ Reservoir Beyond the influence of the discharge ( dilution > 100: 1), generally in a direction toward the headwaters of the lake/ reservoir if possible Estuary/ Ocean Beyond the influence of the discharge ( dilution > 100: 1), generally in a direction away from the movement of the discharge plume at the time of sampling River/ Stream   Grab, under low flow conditions Lake/ reservoir   Grab Estuary/ Ocean   Grab ( slack tide) for acute; tidal composite for chronic 5.5. Sampling Schedule Specify the number of samples, frequency of sampling, study period, and any other conditions ( e. g., season, stream flow) affecting the sampling schedule.

Select the number of samples   see Section 3.3.

The recommended minimum number of samples for a low flow sampling program is 10; 12 would be appropriate if monthly sampling for a year is desired to incorporate seasonality. If sampling occurs over a wide range of flows or the translator is developed through regression analyses, 20 or more samples may be appropriate.

Select the frequency of sampling   see Section 3.1.2.

Weekly sampling is recommended; monthly sampling may be appropriate if seasonality is expected to be an issue. River/ Stream The interval between samples will have to be somewhat flexible because samples should be collected under low flow conditions; e. g., if a sample is to be collected on Wednesday and the river flow is high 23 on that day, sampling should be collected during periods of typical postponed until the first day operation, particularly with respect to when flow returns to base flow operations that affect the TSS levels, or it will have to be concentration or the concentration or postponed until the next the total: dissolved ratio of the metal( s) planned weekly event. being studied. Estuary/ Ocean Monthly or biweekly sampling may be required if state regulations reference critical monthly tidal periods, such as biweekly neap tides.

Determine the study period   see conducted under base flow conditions, Section 3.1. which could be defined in terms of River/ Stream Generally, the low flow period of the year ( e. g., July through October in the East and Midwest) is preferred, unless the time constraints of the permitting process or the local hydrologic regimen dictate otherwise. Lake/ Reservoir Unless there are seasonal discharges or reservoir operating procedures that significantly affect water quality, study period generally is not critical to study plan. Algal bloom conditions should be avoided. Estuary May need to split sampling between low and high salinity seasons, because large changes in salinity between seasons indicates the dominance of different water sources ( fresh water at low salinity and salt water at high salinity) with potentially different particulate matter concentrations or binding capacities. Ocean Unless seasonal currents significantly affect water quality, study period generally is not critical to study plan.

Determine other important considerations Plant operating conditions should be considered. Samples should be If copper is being studied by an electric utility, and the plant has copper and non copper condenser tubes, sampling should occur when the units with copper tubing are operating. River/ stream Sampling should be measured stream flow ( e. g., less than the 25th percentile low flow), stream stage ( e. g., stream height less than 1.5 feet at gaging station XYZ), turbidity ( e. g., less than 5 NTU), TSS concentration ( e. g., less than 10 mg/ L), visual appearance ( e. g., no visible turbidity), or days since last significant rainfall ( e. g., more than 3 days since rainfall of 0.2 inches or more). Lake/ Reservoir As long as the sampling location is unaffected by runoff, hydrologic considerations are not significant. Estuary/ Ocean Since acute criteria are generally considered to have an exposure duration of 1 hour, samples for acute translators should be collected under worst case tidal conditions   generally low slack when dilution is typically at its lowest. Chronic criteria are usually expressed with a 4 day average exposure duration, so sampling over a tidal cycle is appropriate for chronic translators. If the discharger is willing to accept the conservatism of sampling for a chronic translator under worst case conditions   slack tide   then sampling costs could be reduced substantially.

5.6. Preparation 24 Prepare a list of equipment and supplies Prepare a list of contacts and phone that need to be assembled before each sampling numbers. event; for example,

Sample bottles, labeled, with preservative ( for total recoverable)

Samples bottles, labeled, without correct procedure for collecting a sample at any preservative ( for dissolved station.

Sample bottle carrier, e. g., clean plastic Start with guidance on the careful cooler sampling techniques necessary to avoid sample Waterproof marker for filling in bottle labels 1. Given the low metals concentrations Chain of custody form taken to ensure that samples are not Sampling gear   e. g., sampling bottle, Smoking or eating is not permitted sampling pole ( plastic or aluminum if while on station, at any time when aluminum is not being studied), high sample bottles are being handled, or speed peristaltic pump and teflon during filtration. tubing Field portable glove box ( for on site wear clean clothing, i. e., free of dirt, filtering and compositing) grease, etc. that could contaminate Plastic gloves ( non talc) sampling apparatus or sample bottles.

Filtering apparatus, if required for field 3. An equipment blank should be done crew with the actual equipment used for the Field notebook or log sheet blank described in this section should Safety equipment equipment BEFORE the environmental Describe cleaning requirements for serve to verify equipment and sampling sample bottles and sampling equipment that protocol cleanliness. will come in contact with samples.

Select standard or clean apparatus or sample bottles should wear sampling/ analysis. the sampling gloves provided. One Prepare a list of actions to be bottles, and that person should touch completed before the sampling event, such as nothing else while collecting or contacts to be made ( discharger, consultant, transferring samples. laboratory, regulatory agency). 5.7 Sampling Procedure Prepare detailed instructions on the contamination. For example,

expected, extreme care needs to be contaminated during sample collection.

2. Each person on the field crew should environmental samples. The field be performed with the sampling samples are collected. This blank will 4. Each person handling sampling person only should handle sample Then provide step by step instructions 25 for the sampling crew to follow. The specific Are hydrologic conditions ( e. g., base steps will vary depending on what type of flow, slack tide) acceptable? water/ wastewater is being sampled and what type of sampling device is being used. For grab Describe in clear, simple instructions samples collected by hand using a sampling the sequence of actions that the field crew will pole to which the sample bottles are attached, follow from the beginning to end of a sampling the guidance might continue: event. This sequence will vary from project to 5. Attach unpreserved bottle to sample collecting pole. Plunge pole 2 to 3 feet 1. Before embarking, confirm number and under water surface quickly. Pull type ( preserved/ unpreserved) of sample sample bottle up and fill preserved bottles, and read off checklist of bottle from unpreserved sample bottle, equipment/ supplies. leaving ½ to 1 inch of air space at the top. Swirl to mix acid, close cap 2. Before beginning sampling, fill in tightly, and return bottle to carrier. chain of custody forms and bottle 6. Collect duplicate sample by plunging of sampling. unpreserved sample bottle back under water, retrieving, and capping bottle Each bottle should have a unique tightly for dissolved sample, again sample number, and it should be leaving ½ to 1 inch of air space in the labeled " Total" or " Dissolved." If bottle. Return bottle to carrier. preservative has been added to the Other sampling procedures may be should note that fact. chosen to produce acceptable quality data, e. g. Chain of custody forms pre prepared a closed sampling system with immediate with everything but the sampling date sample processing. Equipment for in line and time are recommended. sample collection used for filtering with the Provide sample chain of custody form ( essentially mandatory) Gelman capsule filter and bottle label as attachments to study can be used for sample collection. See Method plan. 1669 § 8.2.8 for a description of sampling steps and Method 1669 § 8.3 for on site composting 3. At Station 1, fill in sampling time on and filtration in a glove box. See also label of two samples bottles, one Appendix E. 2. preserved and one unpreserved.

5.8. Field Protocol Provide a list of criteria which the field form   weather, hydrologic conditions, crew leader should review before starting plant operating status ( if known), sampling to ensure that proper conditions exist. sample bottle numbers and collection Is there a discharge? Are operating observations or circumstances. conditions at the facility appropriate for measuring the metals of concern in the 4. At Station 2, fill in sampling time on effluent? labels of two sample bottles, one project. Typical steps might include:

labels with all information except time bottles before sampling, the label Collect samples following the procedure outline above. Return bottles to carrier immediately after collection. Fill in field notebook or log time ( total and dissolved), and unusual 26 preserved and one unpreserved. automatic samplers, field filtering, and Collect samples following the overnight shipping of samples. Because data procedure outline above. quality is directly dependent on quality control, Return bottles to carrier the Quality Control Supplement( EPA, 1994a) immediately after collection. should be reviewed. Fill in field notebook or log form   weather, hydrologic conditions, plant operating status ( if known), sample bottle numbers and collection time Describe the method for calculating the ( total and dissolved), and chemical translator. unusual observations or circumstances. Select a calculation procedure   see 5. After finishing at Station 2, collect the Specify the treatment for values below field blanks   one preserved and one the detection level   see Section 4.2. unpreserved. Fill in sampling time on label, open sample bottle, and pour in laboratory water. Cap bottles tightly and place in carrier. Note bottle numbers and collection time in field Provide a schedule for the entire study, notebook or log sheet. from selection of consultant or mobilization of If additional sampling gear is used in report. collecting the samples, the field blanks should be collected by rinsing that gear Link schedule to receipt of approval three times with the laboratory water, from state, if required and then filling the gear with enough Emphasize impact of delays on study if water to transfer to the 2 field blank sampling must occur within a certain bottles. If a pump or an automatic calendar timeframe sampler is used, several sample bottle Incorporate contingencies for sampling volumes of laboratory water should be events postponed because of pumped through the sampler tubing unacceptable conditions before the field blank bottles are filled.

6. Complete chain of custody. Check bottle carrier to ensure bottles are upright and well packed. Provide a signoff line for state 7. Deliver samples to laboratory. Have not mandatory. sample custodian sign chain of custody for receipt of samples, and obtain a copy of the chain of custody.

Depending on the project, additional instructions may be needed for setting up 5.9. Data Analysis Sections 1.5.

5.10. Schedule field effort through completion of final study 5.11. State Approval regulatory agency. This is recommended, but 27 6. BUILDING A SPREADSHEET MODEL s discussed in earlier chapters, For example, with Eqn 6.1, the Aa series of steps must be taken downstream TSS concentration is estimated to implement the dissolved from mass balance calculations of upstream metals policy, including converting the water and effluent loadings: quality criteria from the total recoverable to the dissolved form, translation from the dissolved CCC or CMC to the total recoverable metal concentration in the discharger's waste stream, calculating the WLA or TMDL, and developing the permit limit. These steps or calculations are easily handled using a simple spreadsheet model. Use of these equations, whether in a spreadsheet or not, can avoid many common mistakes.

The following equations may be used to translate dissolved criteria to total recoverable permit limits with translators developed through studies such as those described in Chapter 5. This model may be used as a static model with design flow conditions, it may be used in a continuous mode ( i. e.., using daily flow and other data), or it may be used ( with programs such as @ RISK or Crystal Ball ) to perform Monte Carlo analyses. These calculations do not provide concentration estimates between the point of discharge and the point of complete mixing.

The in stream total recoverable concentration is estimated by solving the following equation:

C = ( Q C + Q C ) / ( Q + Q ) t u u e e u e [ Eqn 6.1]

where C = pollutant concentration at the t edge of the mixing zone, Q = upstream flow, u C = upstream pollutant u concentration ( background), Q = effluent flow, e C = effluent pollutant e concentration, and = fraction of flow available for mixing.

TSS = ( Q TSS + Q TSS ) / ( Q + Q ) u u e e u e [ Eqn 6.2]

For translators developed from partitioning equations , ( Eqn 2.7), the 16 dissolved in stream concentration can be expressed as:

C = C / ( 1+ K TSS) [ Eqn 6.3] d t p By setting the dissolved in stream concentration ( C ) equal to the dissolved d criterion concentration ( C = CC ) and d d rearranging the equation, we can solve for the in stream total recoverable concentration ( C ') t that equates to a dissolved in stream concentration equal to the dissolved criterion. Note that this corresponds to Eqn 2.5.

C ' = CC ( 1+ K TSS) [ Eqn 6.4] t d p The total recoverable concentration in the effluent ( C ') that equates to a dissolved in e stream concentration which equals the dissolved criterion in the mixed receiving waters is calculated by Eqn 6.5. This represents the maximum release that will still allow attainment of water quality standards,

If the translator has been determined directly 16 from measurements of dissolved and total recoverable metal in the downstream water, Eqns 6.3 and 6.4 are not be used. Instead, the dissolved criterion concentration is divided by f to calculate C ' which in turn is used in Eqn D t 6.5. If the partition coefficient has units of L/ kg, then both Eqns 6.3 and 6.4 contain the term 1E 6. 28 that is the maximum WLA or the maximum Streamix, an EPA developed TMDL. spreadsheet application for mixing zone C ' = ( C ' ( Q + Q )  Q C ) / Q e t u e u u e [ Eqn 6.5]

Table 4 presents a simple spreadsheet that utilizes these relationships. Note that the second equation in the spreadsheet calculates K and the third equation calculates the P associated f . In studies where the translator is D developed directly as f , the K equation in the D P spreadsheet is deleted and f is changed from D an equation to an input parameter. analyses, has been enhanced to consider metal partitioning between dissolved and particulatesorbed forms. This version, developed for EXCEL, is called METALMIX and provides details of mixing between the point of discharge and the point of complete mix.

Beyond these approaches, EPA's DYNTOX model ( USEPA, 1995c) has been modified to properly account for the distribution of metals between dissolved and particulate sorbed forms. DYNTOX supports Continuous Simulation, Monte Carlo, and Lognormal Probabilistic Analyses Table 4. Spreadsheet to Calculate Total Recoverable Waste Load Allocation based on Dissolved Criterion Variables: Input Values: Q_ u 104 TSS_ u 325 C_ u 19 Q_ e 8.75 TSS_ e 1845 Hardness_ u 100 Hardness_ e 50 mixing fraction ( theta) 0.25 Equations: CC_ d = EXP( a* LN( Hardness_ mix)+ b)* conv_ fact < dissolved criterion concentration> Kp = 2.8* TSS_ mix^ 0.8 < example only> fD = 1/( 1 + Kp* TSS_ mix) Hardness_ mix =( theta * Q_ u * Hardness_ u + Q_ e * Hardness_ e) / ( theta * Q_ u + Q_ e) TSS_ mix =( theta * Q_ u * TSS_ u + Q_ e * TSS_ e) / ( theta * Q_ u + Q_ e) C_ t_ prime = CC_ d*( 1 / fD) < instream total recov conc that equates to dissolved criterion> C_ e_ prime =( C_ t_ prime * ( theta * Q_ u + Q_ e)  theta * Q_ u * C_ u)/ Q_ e < effluent total recov conc resulting in the dissolved criterion in receiving water> 29 7. REFERENCES Benedetti, M. F., Milne, C. J., Kinniburgh, D. G., Van Riemskijk, W. H., and Koopal, L. K. 1995. U. S. Environmental Protection Agency Metal Ion Binding to Humic Substances: ( USEPA). 1983. Methods for Chemical Application of the Non Ideal Competitive Analysis of Water and Wastes. EPA 600 4 79 Adsorption Model. Environ. Sci. Technol. 020. 29,446 457.

Di Toro, D. M. 1985. A Particle Interaction ( USEPA). 1984. Technical Guidance Manual Model of Reversible Organic Chemical for Performing Waste Load Allocations  Book Sorption. Chemosphere 14( 10): 1503 1538. II Streams and Rivers  Chapter 3 Toxic Gilbert, R. O. 1987. Statistical Methods for Environmental Pollution Monitoring. Van U. S. Environmental Protection Agency Nostrand Reinhold, NY. ( USEPA). 1991a. Technical Support Horowitz, A. J., Lum, K. R., Lemieux, C., Control. EPA 505 2 90 001. Garbarino, J. R., Hall, G. E. M., Demas, C. R. 1996. Problems Associated with Using U. S. Environmental Protection Agency Filtration to Define Dissolved Trace Element ( USEPA). 1991b. Methods for the Concentrations in Natural Water Samples. Determination of Metals in Environmental Environmental Science & Technology, Vol 30, Samples. EPA 600 4 91 010. No 3.

Shi, B., Grassi, M. T., Allen, H. E., Fikslin, T. J., ( USEPA). 1992. Guidelines for Exposure and Kinerson, R. S. 1996. Development of a Assessment; Notice. Federal Register Chemical Translator for Heavy Metals in 57( 104): 22888 22938. Receiving Water. Paper Presented at Water Environment Federation 69th Annual U. S. Environmental Protection Agency Conference & Exposition, Dallas, TX ( USEPA). 1994a. Quality Control Supplement Snedecor, G. W. 1956. Statistical Methods. Water Quality Criteria Levels Using EPA The Iowa State University Press, Ames, Iowa, Metals Methods. Engineering and Analysis 534pp. Division ( 4303), USEPA, Washington, DC Steel, R. G. D. and Torrie, J. H. 1980. Principles and Procedures of Statistics, A U. S. Environmental Protection Agency Biometrical Approach. Second Edition. ( USEPA). 1994b. Methods for the McGraw Hill. Determination of Metals in Environmental Sung, W. 1995. Some observations on surface partitioning of Cd, Cu, and Zn in estuaries. U. S. Environmental Protection Agency Environ. Sci. Technol. 29: 1303 1312. ( USEPA). 1995a. Method 1669, Sampling Thomann, R. V. and Mueller, J. A. ( 1987) Metals at EPA Water Quality Criteria Levels. Principles of Surface Water Quality Modeling and Control. HarperCollins Publishers Inc, New York, NY, 644pp.

U. S. Environmental Protection Agency Substances. EPA 440 4 84 022.

Document for Water Quality based Toxics U. S. Environmental Protection Agency for Determination of Trace Metals at EPA 20460, December 1994.

Samples. EPA 600 R 94 111.

Ambient Water for Determination of Trace 30 EPA 821 R 95034.

U. S. Environmental Protection Agency ( USEPA). 1995b. Guidance on the Documentation and Evaluation of Trace Metals Data Collected for Clean Water Act Compliance Monitoring. Engineering and Analysis Division ( 4303), Washington, DC 20460, December 1994.

U. S. Environmental Protection Agency ( USEPA). 1995c. Dynamic Toxics Wasteload Allocation Model ( DYNTOX). EPA 823 C 95 005.

Zar, J. H. 1984. Biostatistical Analysis. Second Edition. Prentice Hall,, NJ. WQC Metal exp a ln( H) b 31 ( 1) APPENDIX A Deriving Permit Limits for Metals his Appendix summarizes the Tsteps involved in applying the dissolved metals policy and illustrates how the translator is used in developing a permit limit. Water quality standards consist of degradation statement. The river, in this A. 1 The Setting for the Example Our example site is a river which has recreation ( i. e., " fishable, swimmable"), and been identified as being water quality limited the State has adopted the federal water quality because of high copper concentrations with criteria into its water quality standards to potential adverse impacts on aquatic life. protect aquatic life and human health. The Copper loading to the impaired reach comes numeric water quality criteria for acute toxicity from naturally occurring and anthropogenic ( criterion maximum concentration, or CMC) sources in the watershed ( background) and and chronic toxicity ( criterion continuous permitted point source discharges, including concentration, or CCC) to aquatic life are part two metal plating facilities and a publicly of the water quality standards and are based on owned treatment works ( POTW). For the sake the dissolved fraction of metals. The CMC and of simplicity, steady state modeling is used. CCC depend on ambient hardness Episodic, precipitation driven runoff loadings concentrations as expressed by the following from urban and industrial areas adjacent to the equation form ( as total recoverable metal): river could be accounted for using continuous simulation.

Design low flows are typically used for calculating steady state wasteload allocations ( WLAs), including the 1 day average low flow with a ten year recurrence period ( 1Q10) for where a and b are metal specific constants acute criteria and the 7 day average low flow defined as part of the water quality criterion. with a ten year recurrence period ( 7Q10) for For copper in freshwater systems, these chronic criteria. Analysis of 30 years of constants are: records from the USGS gage above the sources indicates a 1Q10 flow of 111.77 cfs and a 7Q10 flow of 140.09 cfs.

The two metal plating facilities in our example have multiport diffusers, which have been shown to quickly achieve complete mixing across the width of the river. The POTW effluent enters the same reach as the facility discharges and is released to a bend in the river where mixing also occurs rapidly. The State's water quality regulations require that water quality criteria are met at the edge of the mixing zone.

A. 2 Water Quality Standards and Criteria criteria, designated uses, and an antiexample is classified as having designated uses for aquatic habitat and primary contact Copper a b Chronic Criteria 0.8545  1.465 ( µ g/ L)

Acute Criteria 0.9422  1.464 ( µ g/ L) 32 Box A 1. Calculation of Acute ( CMC) and Chronic ( CCC) WQC for Copper Hardness ( mg/ L) 100 Conversion Factor 0.96 CMC ( µ g/ L) = ( total recoverable)

exp[. 9422 x ln( 100)  1.464] = 17.7 CMC ( µ g/ L) = 17.7 x .96 = 17.0 ( dissolved)

CCC ( µ g/ L) = ( total recoverable)

exp[. 8545 x ln( 100)  1.465] = 11.8 CCC ( µ g/ L) = 11.8 x .96 = 11.4 ( dissolved) At 100 mg/ L hardness, these lead to a CCC of 11.8 µ g/ L and a CMC of 17.7 µ g/ L. These criteria concentrations are expressed on the basis of total recoverable metal ( Box A 1).

A. 3 Change from Total Recoverable to Dissolved Criteria As illustrated in Box A 1, each metal's total recoverable criterion must be multiplied by a conversion factor to obtain a dissolved criterion that should not be exceeded in the water column. The criteria are based on a total recoverable concentration. For example, the copper acute ( and chronic) conversion factor of 0.960 is a weighted average and is used as a prediction of how much the final value would change if dissolved had been measured. Where can then be used to translate from a dissolved possible, these conversion factors are given to concentration in the water column ( the criterion three decimal places as they are intermediate concentration or some fraction thereof ) to the values in the calculation of dissolved criteria. total recoverable metal concentration in the At a hardness of 100 mg/ L, the acute dissolved effluent that will equate to that dissolved criterion is 17.0 µ g/ L. Most of the freshwater concentration in the water column. aquatic life criteria and their conversion factors are hardness dependent. Box A 1 shows an example calculation of dissolved and total recoverable copper criteria concentrations.

A. 4 Translating from a Dissolved Metal Ambient Criterion to a Total Recoverable Concentration in the Effluent As the effluent mixes with the recoverable copper in the river at low flow receiving water, the chemical properties of the ( upstream of the effluent discharge) is 4 µ g/ L mixture will determine the fraction of the metal and varies within a relatively small range, from that is dissolved and the fraction of the metal less than 2 to 9.5 µ g/ L, with the average that is in particulate form ( typically adsorbed to declining to about 3 µ g/ L above median flows. surfaces of other compounds). The most direct For this analysis the mean background approach to determining the fraction of the total concentration is used. recoverable metal in the downstream water that is dissolved ( f ) is to analyze the downstream The ( instream) total recoverable D water ( the mixing zone of effluent and concentration [ C ] that equates to the receiving water) to determine the dissolved and dissolved criterion concentration is expressed total recoverable metal fractions. This ratio as: A. 5 Calculation of WLAs for a Point Source For this example, it is assumed that the site specific data have been collected and analyzed to determine that f = 0.4. D From analysis of existing data, the average background concentration of total instream [ C instream] WQC( dissolved) 1 f D WLA( total metal) [ C instream] ( Q e Q s) Q s C s Q e WLA a 42.5 ( 50 111.77) 111.77 4 50 128.6 µ g/ L total recoverable Cu 33 ( 2)

( 3)

( 4) Box A 2. Data for Calculation of WLAs and Existing Permit Limits for the POTW Effluent Flow ( cfs) 50 Average Effluent Concentration, as Total Recoverable Copper ( µ g/ L) 81 Coefficient of Variation of Load 0.12 Given the information on the design other words, the full assimilative capacity of flows and background concentrations ( Box A the water body is not available to each source; 2), WLAs, expressed as total recoverable instead, this capacity must be apportioned metal, are calculated to meet the dissolved between all three sources via the TMDL CCC and dissolved CMC at the edge of the procedure. mixing zone assuming that the effluent is mixed rapidly and that a simple, mass balance The three permitted point sources in equation is appropriate. our example all operate within the effluent Chronic and acute WLAs ( for any permits. They do not, however, address single source, without consideration of other cumulative impacts of all three sources. sources) can be calculated at the 7Q10 and Permits for the two metal finishing facilities 1Q10 flows, respectively, for total recoverable specify a maximum daily limit ( MDL) of copper concentration, using Equation 3. 3380 µ g/ L and an average monthly limit where [ C ] is calculated from Equation 2, effluent concentrations. At an average instream Q is the effluent flow, concentration of 81 µ g/ L of total recoverable e Q is the receiving water flow, and copper and an increased effluent flow of 80 s C is the background ( upstream ) cfs, the load from the POTW ( see Box A 3) s concentration. would be 35 lbs/ day. The increased flow A. 6 Calculating the TMDL for Multiple Point Sources The previous section shows the calculation of wasteload allocations for a single point source. Concentrations in the receiving water, however, are influenced by all three point sources simultaneously. In limits specified in their current NPDES ( AML) of 2070 µ g/ L.

In addition to potential impairment under current permit limits, the POTW is undergoing a significant ( 60%) capacity expansion, and its increased effluent flow will also increase copper loading at current from the plant also has a significant impact on low flow volumes in the receiving water, requiring recalculation of the WLAs.

The TMDL analysis is straightforward when multiple, steady state sources are considered using hydrologically based design conditions. The strategy is to: TMDL WQC ( Q e Q s)

TMDL [ C instream] ( Q e Q s)

34 Box A 3. Conversion Factors for Concentration and Load Concentration to load rate: ( µ g/ L) x ( cfs) x 0.005394 = ( lbs/ day)

Load rate to concentration: ( lbs/ day) / ( cfs) x 185.4 = ( µ g/ L) ( 5)

( 6) ( 1) calculate the acute and chronic dissolved ( for metals) criteria concentrations [ Eqn 1],

( 2) calculate the instream concentration [ C ] ( in terms of total recoverable metal) instream that equates to the dissolved criterion concentration [ Eqn 2],

( 3) calculate the total loading capacity ( TMDL) of the waterbody ( in terms of total recoverable metal) [ Eqn 6],

( 4) calculate the background load,

( 5) calculate the allocatable portion of the loading capacity ( i. e., the difference between the loading capacity and background) [ Eqn 7],

( 6) calculate the current loadings from the sources and their fractional contributions to the total current load,

( 7) compare the current total loadings to the waterbody with the required TMDL ( if either the acute or chronic total loadings exceed the TMDL then the loads must be reduced), and ( 8) reduce loadings from the point sources, equitably allocating waste loads to the discharging facilities. The steady state TMDL for a given location or reach of the river is calculated ( in units of cfs  µ g/ L) as:

where Q is the total flow of effluents e discharging to the reach ( cfs), Qs is the appropriate flow ( e. g., 7Q10) of the river upstream of all the discharges ( cfs), and WQC is the water quality criterion expressed in µ g/ L.

TMDLs for metals are developed on the basis of the instream total recoverable metal concentrations that equate to the dissolved criteria concentrations. Consequently, the term WQC in Equation 5 is replaced with the term [ C ] as calculated instream by Equation 2.

The calculated TMDL is then divided among WLAs for point sources; LAs, for nonpoint sources and background loads; and a margin of safety ( MOS). The TMDL and the portion of the TMDL taken up by background load ( at 4 µ g/ L) can be calculated in terms of total copper mass, as shown in Table A 1.

Because the current loading for the chronic TMDL exceeds the allocatable portion, loadings from all of the NPDES permitted sources must be reduced. Many different mechanisms or schemes for apportioning the necessary reductions in allocations are possible. Assume for the purpose of this example that the State has determined that necessary reductions will be applied equally to all point sources. Reduced TMDL based WLAs can then be calculated based on the current proportion of load attributable to a given source: WLA i TMDL Background x f i 35 ( 7)

where WLA is the WLA for source I, and f i i is the proportion of the existing load attributable to a given source.

The allocation fraction, f , is simply a i proportionality constant that is arrived at by dividing the current load from source by the i sum of all the loads ( e. g., f = PS1 / ( PS1 + 1 PS2 + POTW + MOS)). The allocation fraction is then multiplied by the Allocatable Portion to yield the Allowed Load as in Table A 2. In the calculations summarized in Table A 2 and A 3, a MOS of 10 percent of the allowable TMDL has been applied. 36 Table A 1. Calculation of TMDL ( Total Recoverable Copper)

Acute TMDL Chronic TMDL TMDL ( lbs/ day) 44.11 33.76 ( total recoverable copper)

[ Eqn 6]

Background at design flow ( lbs/ day) 2.41 3.02 ( total recoverable copper)

[ Background = Q * C ] s s Allocatable Portion ( lbs/ day) 41.69 30.73 [ Allocatable Portion = TMDL  Background]

Current Loading ( lbs/ day) 42.38 42.99 [ Loading = PS1 + PS2 + POTW + Background]

.

Table A 2. Allocation of Loads to Achieve the ( Chronic) TMDL Source Current Load Allocation Allocatable Allowed Load ( lbs/ day) Fraction Portion ( lbs/ day) ( f ) i ( TMDL  Background)

PS1 1.67 0.04 30.73 1.16 PS2 3.35 0.08 30.73 2.32 POTW 34.95 0.79 30.73 24.18 MOS 4.44 0.10 30.73 3.07 SUM 44.41 1 30.73 37 Table A 3. Allocation of Loads to Achieve the ( Acute) TMDL Source Current Load Allocation Allocatable Allowed Load ( lbs/ day) Fraction Portion ( lbs/ day) ( f ) i ( TMDL  Background)

PS1 1.67 0.04 41.69 1.57 PS2 3.35 0.08 41.69 3.14 POTW 34.95 0.79 41.69 32.81 MOS 4.44 0.10 41.69 4.17 SUM 44.41 1 41.69 LTA c WLA exp [ 0.5 24 z 99 4]

24.18 lbs/ day 0.87 21.0 lbs/ day LTA a 32.81 lbs/ day 0.76 24.9 lbs/ day 38 Box A 4. Calculation of LTA Multipliers LTAc CV = 0.12 z = 2.326 99 ² = ln [ CV ² / 4+ 1] = 0.00359 4 exp [ 0.5 ²   z ] = 0.87 4 99 4 LTAa CV = 0.12 z = 2.326 99 ² = ln [ CV ² + 1] = 0.014297 exp [ 0.5 ²  z ] = 0.76 99 ( 9)

( 10) A. 7 Calculating the Permit Limits for a Point Source Permit limits for the POTW are developed in accordance with USEPA ( 1991a) guidance on establishing WLAs and permit limits for single sources. In accordance with NPDES regulations, effluent limits for the POTW are expressed in the permit as mass units ( pounds per day total recoverable copper), using the conversion factors shown in Box A 3. The WLA for c total recoverable copper ( Table A 2) is equivalent to 24.18 lbs/ day and is more restrictive than the WLA 32.81 lbs/ day a ( Table A 3). Converting the WLA to a permit limit involves two additional considerations: ( 1) there is variability in the effluent concentration, and concentrations on any given day may be greater or less than the average value used to calculate the WLA; and ( 2) permit compliance will be assessed from limited sampling ( e. g., weekly), which means there will be uncertainty in the estimation of actual load from the facility. These issues are addressed by ( 1) calculating a long term average ( LTA) which accounts for the variability in actual load, and ( 2) using the LTA to calculate a maximum daily limit ( MDL) and average monthly limit ( AML) which serve as trigger values for compliance monitoring.

The permit limits are developed using a steady state, two value WLA model, as described in Chapter 5 of USEPA ( 1991a). First, variability in effluent load, expressed through the coefficient of variation ( CV), is incorporated into the calculation of appropriate long term averages ( LTAs). The chronic long term average ( LTA ) for copper c was calculated from where the value for the factor exp [ 0.5 ²   4 z ] was calculated from the coefficient of 99 4 variation of effluent concentrations ( CV, defined as standard deviation divided by the mean, and assumed to be 0.12) by the methods of USEPA ( 1991a, Table 5 1), using the 99th percentile occurrence probability ( Box A 4).

The acute LTA was calculated in a a similar manner, again using a 99th occurrence probability as a multiplier: MDL LTA exp [ z 99 0.5 2]

21.0 lbs/ day 1.37 28.8 lbs/ day AML LTA exp [ z 99 n 0.5 2 n]

21.0 lbs/ day 1.15 24.2 lbs/ day 39 ( 11)

( 12) The limiting LTA for copper discharges from the facility is the smaller of the LTA and a LTA , or 21.0 lbs/ day. This is well below the c current average load from the facility of 43.95 lbs/ day.

The permit for the POTW is written to ensure an LTA load not to exceed 21.0 lbs/ day total recoverable copper through the specification of an MDL and AML for compliance monitoring. The MDL for copper is calculated using the expression where the value for exp [ z   0.5 ² ] is 99 taken from Table 5 2 in USEPA ( 1991a), using a CV value of 0.12 and the column for the 99th percentile basis. The AML for copper is calculated from where the value for exp [ z   0.5 ² ] is 99 n n taken from Table 5 2 in USEPA ( 1991a), in which n equals 4 samples per month for total recoverable copper, using the 99th percentile basis. 40 APPENDIX B Table B 1. Comparison of average f data from three locations in the U. S. Three different D calculation methods are used with the Pima County data.

NY/ NJ Boulder, Pima County, AZ Harbor CO Cd/ Ct Cd/( Cd+ Cp) by regression from logKp Copper 0.56 0.23 0.37 0.43 0.42 Cadmium 1.00 0.51 0.71 0.51 0.69 Lead 0.18 0.29 0.20 0.28 0.26 Nickel 0.86 ~ 1.0

Zinc 0.90 0.44 0.61 0.63 0.65 These data illustrate two points. First, notice the similarity in the values of the translators for each of the metals in the Pima County study. The differences between column 1 and column 2 of the Pima County data arise from limits in the analytical precision of measurements of dissolved and particulate sorbed fractions. Second, notice the differences in the values of the translators between the three sites represented in this table. These differences reflect the site specificity of the translator, further strengthing the case for development of site specific translator values in contrast to the use of nation wide values.

Preliminary data collected for the City of Palo Alto Regional Water Quality Control Plant permit renewal process ( Table B 2) suggest a translator value of 0.62 for copper ( 62% of the copper in the downstream water is dissolved). This differs from all of the translator values in Table B 1. Station# Date Cd Ct Cp TSS fD Station 1 9/ 7/ 89 2.6 3.4 0.8 89 0.76 Station 1 10/ 2/ 89 3.3 4.5 1.2 290 0.73 Station 1 10/ 25/ 89 3 4 1 52 0.75 Station 1 1/ 10/ 90 2.9 4.1 1.2 49 0.71 Station 1 2/ 7/ 90 1.4 8 6.6 228 0.18 Station 1 3/ 7/ 90 3 5 2 77 0.60 Station 1 7/ 9/ 90 4.2 9.6 5.4 180 0.44 Station 1 8/ 7/ 90 6.3 7 0.7 83 0.90 Station 1 9/ 19/ 90 3.6 5.7 2.1 125 0.63 Station 1 12/ 12/ 90 2.9 5.9 3 57 0.49 Station 1 1/ 10/ 91 3.5 4.3 0.8 46 0.81 Station 1 2/ 13/ 91 4 4.7 0.7 55 0.85 Station 1 10/ 10/ 91 4.3 4.6 0.3 78 0.93 Station 1 2/ 19/ 92 2 9.9 7.9 250 0.20 Station 2 9/ 7/ 89 3 5 2 110 0.60 Station 2 10/ 2/ 89 2.2 4.5 2.3 160 0.49 Station 2 10/ 25/ 89 6 11 5 132 0.55 Station 2 1/ 10/ 90 2.9 4.1 1.2 46 0.71 Station 2 2/ 7/ 90 1.7 6.1 4.4 110 0.28 Station 2 3/ 7/ 90 4.3 5 0.7 60 0.86 Station 2 7/ 9/ 90 6.8 7.2 0.4 100 0.94 Station 2 8/ 7/ 90 6.5 8.2 1.7 48 0.79 Station 2 9/ 19/ 90 3.9 5.6 1.7 65 0.70 Station 2 12/ 12/ 90 2.8 4.6 1.8 51 0.61 Station 2 1/ 10/ 91 4.2 4.8 0.6 61 0.88 Station 2 2/ 13/ 91 4.5 4.8 0.3 47 0.94 Station 2 10/ 10/ 91 4.5 4.7 0.2 77 0.96 Station 2 2/ 19/ 92 2 4.9 2.9 120 0.41 Mean 3.7 5.8 2.1 101.6 0.67 Stdev 1.4 2.0 2.0 65.5 0.22 95% 6.4 9.8 6.2 243.4 0.94 25% 2.9 4.6 0.7 54.3 0.53 Geomean 3.4 5.5 1.4 86.6 0.62 41 Table B 2. Data Collected in Palo Alto, CA for Cu Permit Limit from a Waste Water Treatment Plant. 42 APPENDIX C C. 2. The Translator is the Ratio of C. Developing the Metals Translator s may be concluded from the calculated from data collected over some Adiscussion in Chapter 2, period of time and some range of flow there are several ways of conditions. For example, samples may be developing the metals translator. This collected weekly for three months under Appendix presents two suggested possibilities conditions of " relatively low flow" ( which and illustrates their application. may or may not include design low flow C. 1. Minimum Data Requirements Samples should be collected to expect to have a broad range of TSS characterize completely mixed effluent plus conditions. The dissolved fraction may be receiving water downstream of the discharge determined ( directly) from measurements of ( such as should occur at, or below, the edge dissolved and total recoverable metal of the mixing zone). These represent the concentrations collected from waters absolute minimum in data requirements. downstream of the effluent discharge. The Ideally, samples should be collected from the dissolved fraction may be related to a constant effluent and the upstream receiving water adsorbent concentration associated with low ( before mixing with the effluent ) to quantify flow conditions or a function of varying metal loading and background adsorbent concentrations. concentrations. An alternative to collecting the downstream samples on site is to combine Note that this ratio ( C / C ), as upstream and effluent waters to meet the exemplified by Eqn 2.6 and 2.7, is not a desired dilution fraction in the mixing zone. partition coefficient but it does embody a In addition, there may be occasions when it is partition coefficient. As shown by Eqn 2.3 desirable to collect samples to characterize and Eqn 2.8, the partition coefficient is the the far field conditions, particularly when ratio of the particulate sorbed and the encountering deposits containing metals, mine dissolved metal species. The dissolved tailings, drainage waters of high acidity, or fraction and the partition coefficient are different geologic substrates. related according to f = ( 1 + K ° m) . It is To keep this simple and to avoid fraction ( f ) and the partition coefficient ( K ) having to develop data on the kinetics of because what we're interested is the dissolved metal adsorption and desorption, the translator fraction. We're only using the partition should be developed to describe equilibrium coefficient because it is one way of getting to partitioning. Equilibrium partitioning also the dissolved fraction. reduces the frequency for which far field effects need to be investigated. It also lets us This guidance uses TSS as a default apply the same translator for evaluation of parameter to represent all of the ion both acute and chronic mixing zones. adsorption sites. It is generally recognized, C / C D T The translator is the fraction of the total recoverable metal in the downstream water that is dissolved ( f = C / C ). It is D D T conditions) or samples may be collected monthly for a period of one or more years under a broad range of flow conditions. Under this latter sampling scheme we may D T D P  1 important to distinguish between the dissolved D P however, that humic substances play a major 43 Box C 1. The Translator is the Dissolved Fraction: f = C / C D D T Step 1  For each field sample determine f = C / C D D T Step 2  If the translator is not dependent on TSS, determine the geometric mean GM_ f = exp( ln( f )/ n) D 1 D n and upper percentile values of the dissolved fraction. If the data are found not to be log normal, then alternative transformations should be considered to normalize the data and determine the transformed mean and percentiles. Also, alternative upper percentiles may be adopted as a state's policy to address MOS ( e. ge., 90 or 95 th th percentiles may be appropriate.)

Step 3  If the translator is found to be dependent on TSS, regression equations relating f to TSS should D be developed. Appropriate transformations should be used to meet the normality assumptions for regression analysis ( for example log transformation of f D and TSS may be appropriate). The regression equation or an upper prediction interval may be considered for estimation of f D from TSS depending on the strategy for addressing MOS. role in the environmental fate and availability from Table 1 and following the sequence as of metal ions in the environment. The humic outlined in Box C 1. The metal and fulvic acids are mixtures of naturally concentrations in Table 1 are for lead. The occurring polyelectrolytes that have different data records, numbers 1 through 27, represent types of functional groups to which ions can spatially separate sampling stations in the bind. Benedetti, et. al. ( 1995) write that metal estuary. The first step ( Step 1 in Box C 1) is binding in natural systems will be affected by to calculate the dissolved fraction in the humic acids whose chemical heterogeneity receiving water. The result of this calculation and polyelectric properties will affect metal is shown in Column 8 of Table 1. binding. Multivalent cations will compete for the same sites, along with other ions and protons in the aquatic systems, and hence influence the binding of each other.

The following step by step examples are designed to guide the reader through possible sequences of data analyses leading to the development of the metals translator. One set of data was collected during the New York/ New Jersey Harbor study. The data presented here are a subset of the total and do not include samples that are incomplete ( i. e., records lacking pH or POC values) to simplify this presentation. The data set reflects spatial differences. The data are not a time series at a single location. However, there would not be a great difference in the following analyses if the data did represent a time series.

The second data set was provided by the Coors Brewing Company. Again, the data presented here are a subset of the total. The original data set contains time series data for several variables at several locations. To simplify this example, however, the data for only one metal and one site are presented.

C. 2.1. Spatial Example Using the Ratio of C / C D T The most direct procedure for determining a site specific metal translator is simply to determine f by measuring C and D T C and to develop the dissolved fraction as D the ratio C / C . This is illustrated, using data D T Lead 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0 20 40 60 TSS fD Lead  0.10 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70  1.00 0.00 1.00 2.00 3.00 4.00 ln ( TSS) fD R Square = 0.77 44 Step 2 indicates that there is a lot of transformations would be appropriate. variation in the values of f ; the mean is 0.21 Examination of Figure 2 further supports the D with a standard deviation is 0.17. The logarithmic transformation of values and the variability in this dataset indicates that it is choice of the geometric mean. Even at that, unwise to attempt to spatially average f the geometric mean value of the dissolved D values in this situation. To do so would be to fraction ( 0.16 does not provide a good ignore spatially critical conditions. Because, representation of the waterbody in which TSS it does not provide a good representation of is spatially correlated. The translator needs to the waterbody, one cannot accept the mean f account for the spatial and/ or temporal D ( 0.21) as the translator. variability evidenced in the waterbody.

The translator should be calculated as a geometric mean or other estimate of central tendency ( see Section 4.3). Use of the arithmetic mean is appropriate when the values can range from minus infinity to plus infinity. The geometric mean is equivalent to using the arithmetic mean of the logarithms of the values. The dissolved fraction cannot be negative, but the logarithms of the dissolved fraction can be. The distribution of the Figure 1. Dissolved fraction ( lead) vs TSS.

logarithms of the translator is therefore more likely to be normally distributed. Figure 1 displays the arithmetic distributions of the dissolved fractions with TSS. Note that the skewed distributions suggest that logarithmic In order to account for the spatial variability of this waterbody, we need a translator that can be tied functionally to important physical or chemical variables. TSS concentrations vary spatially throughout the estuary. Spatial variability in TSS concentrations requires the use of a translator that includes the relationship between TSS and f . This empirically derived relationship D is valid for this estuary.

Figure 2. Dissolved fraction ( lead) vs log transformation of TSS.

The regression of the natural logarithm of f against the natural logarithm D of TSS ( Figure 2) provides a reasonably good fit as evidenced by the R Square of 0.77. The 45 dissolved fraction is highly correlated with TSS; therefore the translator ( Figure 2) takes the form of:

ln( f ) =  0.6017  0.6296 ° ln( TSS). D The translator is the dissolved fraction, not the regression equation. The way to use the regression equation is to select TSS concentrations that are representative of specific locations in the estuary and calculate f values that serve as the translators for the D discharges in these respective locations.