©EPA
United States
Environmental Protection
Agency
       Relative Risk Assessment of
       Management Option^ for
       Treated Wastewaten
             Florida
                         NO PUS

-------

-------
SEPA
United States
Environmental Protection
Agency
           Relative Risk Assessment of
           Management Options for
           Treated Waste water in
           South  Florida
          Office of Water (4606M)
          EPA816-R-03-010
          www.epa.gov/safewater
          April 2003
                            Recycled/Recyclable • Printed with Vegetable Oil Based Inks on
                                  Recycled Paper (Minimum 30% Postconsumer)

-------
[ This page intentionally left blank ]

-------
                            TABLE OF CONTENTS

                                                                          Page

EXECUTIVE SUMMARY                                                 ES-1
       Wastewater Challenges in South Florida                                ES-1
       Congressional Mandate for Relative Risk Assessment                    ES-2
       Municipal Wastewater Treatment Options in South Florida                ES-2
             Wastewater Treatment Options                                  ES-3
             Levels of Wastewater Treatment and Disinfection                 ES-4
       Risk Assessment                                                    ES-5
             Approach Used in this Relative Risk Assessment                  ES-6
       Deep-Well Injection                                                  ES-7
             Regulatory Oversight of Deep-Well Injection                    ES-10
             Option-Specific Risk Analysis for Deep-Well Injection            ES-11
             How Injected Wastewater Can Reach Drinking-Water Supplies     ES-11
             Human Health and Ecological Risk Characterization of
                    Deep-Well Injection                                    ES-13
       Aquifer Recharge                                                   ES-14
             Regulatory Oversight of Aquifer Recharge                       ES-14
             Option-Specific Risk Analysis for Aquifer Recharge              ES-15
             Human Health and Ecological Risk Characterization of
                    Aquifer Recharge                                      ES-16
       Discharge to Ocean Outfalls                                          ES-16
             Regulatory Oversight of Discharge to Ocean Outfalls              ES-17
             Option-Specific Risk Analysis for Discharge to Ocean Outfalls     ES-18
             Human Health and Ecological Risk Characterization
                    of Discharge to Ocean Outfalls                           ES-19
       Discharge to Surface Waters                                         ES-19
             Regulatory Oversight of Discharge to Surface Waters              ES-20
             Option-Specific Risk Analysis for Discharge to Surface Waters     ES-20
             Human Health and Ecological Risk Characterization of
                    Discharge to Surface Waters                             ES-22
       Overall Risk Assessment                                             ES-23
             Findings on Risk to Human Health                              ES-24
             Findings on Risk to Ecological Health                           ES-24
       References                                                         ES-26

1.0    INTRODUCTION                                                    1-1
       1.1    Congressional Mandate                                          1-1
       1.2    Purpose                                                       1-1

-------
2.0    BACKGROUND                                                      2-1
       2.1    Wastewater Management Options Used in South Florida              2-1
             2.1.1   Class I Deep Well Injection                                 2-5
             2.1.2   Aquifer Recharge                                         2-6
             2.1.3   Ocean Outfalls                                            2-6
             2.1.4   Surface Water Discharges                                  2-7
       2.2    Drinking Water in South Florida                                   2-7
             2.2.1   Floridan Aquifer System                                   2-9
             2.2.2   Biscayne Aquifer System                                  2-10
             2.2.3   Surficial Aquifer                                         2-10
             2.2.4   Drinking Water Quality in South Florida Communities        2-10
       2.3    General Description of Wastewater Treatment                      2-11
             2.3.1   Wastewater Treatment Methods Used in Florida             2-11
             2.3.2   Definitions of Wastewater Treatment Methods and
                       Levels of Disinfection                                 2-14
       References                                                            2-16

3.0    METHODOLOGY FOR RELATIVE RISK ASSESSMENT              3-1
       3.1    Generic Risk Analysis Framework and Problem Formulation          3-1
       3.2    Option-Specific Risk Analysis and Risk Characterization             3-2
       3.3    Relative Risk Assessment                                         3-3
       3.4    Detailed Description of Problem Formulation                        3-3
             3.4.1   Selection of Potential Exposure Pathways                     3-4
             3.4.2   Definition of Potential Receptors                            3-5
             3.4.3   Selection of Assessment Endpoints                          3-5
             3.4.4   Selection of Potential Stressors                             3-6
                 3.4.4.1  Pathogenic Microorganisms                           3-8
                 3.4.4.2  Inorganic Stressors                                  3-12
                 3.4.4.3  Organic Compounds                                 3-15
       3.5    Analysis Plan                                                   3-19
       3.6    Final Conceptual Model of Probable Risk                          3-20
       3.7    Relative Risk Assessment                                        3-21
       References                                                            3-22

4.0    DEEP WELL INJECTION                                            4-1
       4.1    Definition of the Deep-Well Injection Option                        4-1
       4.2    Deep-Well Capacity and Use in South Florida                       4-1
       4.3    Environment Into Which Treated Wastewater Is Discharged           4-1
             4.3.1   Aquifers in South Florida                                   4-3
             4.3.2   Regional Conditions in Dade County                        4-8
             4.3.3   Regional Conditions in Pinellas County                      4-9
             4.3.4   Regional Conditions in Brevard County                     4-10
       4.4    Ground Water Quality and Fluid Movement in South Florida         4-11
                                       u

-------
              4.4.1  Dade County Groundwater Monitoring Information          4-14
              4.4.2  Pinellas County Groundwater Monitoring Information        4-16
              4,4.3  Brevard County Groundwater Monitoring Information        4-17
                    4.4.3.1   South Beaches                                   4-17
                    4.4.3.2   Palm Bay                                       4-18
       4.5    Regulations and Requirements for the Deep-Well
                 Inj ection Option                                             4-19
       4.6    Problem Formulation                                            4-20
       4.7    Conceptual Model of Potential Risks for the
                 Deep-Well Injection Option                                   4-22
              4.7.1  Potential Stressors                                        4-24
              4.7.2  Potential Exposure Pathways                              4-27
              4.7.3  Potential Receptors and Assessment Endpoints               4-27
       4.8    Risk Analysis of the Deep-Well Injection Option                   4-28
              4.8.1  Application of the Analytical Transport Model               4-29
              4.8.2  Vertical Times of Travel and Horizontal Migration           4-35
                    4.8.2.1   Governing Assumptions for the Transport Model    4-36
                    4.8.2.2   Vertical Time-of-Travel Results and Discussion     4-36
                    4.8.2.3   Horizontal Migration                             4-39
                    4.8.2.4   Transport Model Limitations                      4-40
                    4.8.2.5   Uncertainty Analysis                             4-41
              4.8.3  Evaluation of Receptors and Analysis Endpoints             4-42
                    4.8.3.1   Application of the Stressor Fate and
                                Transport Model                              4-43
                    4.8.3.2   Final Concentrations of Chemical Stressors         4-45
                    4.8.3.3   Fate and Transport of Pathogenic
                                Microorganisms                              4-47
       4.9    Final Conceptual Model of Risk for Deep-Well Injection             4-56
              4.9.1  Injection Pressure Head and Buoyancy Pressure              4-58
              4.9.2  Vertical Time-of-Travel                                   4-59
              4.9.3  Horizontal Distance Traveled in a Given Travel Time         4-59
              4.9.4  Fate of Chemical  Constituents                              4-60
              4.9.5  Comparison with  Monitoring-Well Data                     4-60
              4.9.6  Mechanical Integrity as a Risk Factor                       4-60
              4.9.7  Fate and Transport of Pathogenic Microorganisms            4-62
              4.9.8  Effects of Data Gaps                                      4-63
       References                                                            4-64

5.0    AQUIFER RECHARGE                                                5-1
       5.1    Definition of Aquifer Recharge                                    5-1
       5.2    Use of Aquifer Recharge in South Florida                           5-2
       5.3    Environment into which Treated Wastewater Is Discharged           5-5
              5.3.1  Biscayne Aquifer System                                   5-5
              5.3.2  Surficial Aquifer                                           5-5
                                       in

-------
       5.4    Regulations and Requirements for Aquifer Recharge                 5-6
             5.4.1  Slow-Rate Land Application Systems                        5-6
             5.4.2  Rapid-Rate Land Application Systems                       5-7
             5.4.3  Wetland Systems                                           5-8
       5.5    Problem Formulation                                             5-9
             5.5.1  Slow-Rate Land Application Systems                        5-9
             5.5.2  Rapid-Rate Land Application Systems                      5-10
             5.5.3  Wetland Systems                                          5-11
             5.5.4  Florida DEP Study of Relative Risks of Reuse               5-11
             5.5.5  Potential Stressors                                        5-12
             5.5.6  Potential Receptors and Assessment Endpoints               5-13
             5.5.7  Potential Exposure Pathways                               5-13
             5.5.8  Conceptual Model of Potential Risks of Aquifer Recharge     5-14
       5.6    Risk Analysis of the Aquifer Recharge Option                      5-16
             5.6.1  Vertical and Horizontal Times of Travel                     5-16
             5.6.2  Evaluation of Stressors                                    5-17
             5.6.3  Evaluation of Receptors and Analysis Endpoints             5-19
       5.7    Final Conceptual Model of Probable Risk                          5-24
       5.8    Potential Effects of Data Gaps                                    5-26
       References                                                            5-28

6.0    OCEAN OUTFALLS                                                   6-1
       6.1    Definition of Ocean Outfalls                                       6-1
       6.2    Capacity and Use in South Florida                                  6-1
       6.3    Environment into Which Treated Wastewater is Discharged           6-5
       6.4    Regulations and Requirements Concerning Ocean Outfalls            6-6
             6.4.1  General Requirements                                      6-6
             6.4.2  Secondary Treatment of Wastewater                         6-8
             6.4.3  Basic Disinfection                                         6-8
             6.4.4  Water Quality Standards for Receiving Waters                6-9
       6.5    Problem Formulation                                            6-10
             6.5.1  Potential Stressors                                        6-10
                    6.5.1.1 Nutrients and Eutrophication                        6-11
                    6.5.1.2 Pathogenic Microorganisms                         6-13
                    6.5.1.3 Priority Pollutant Metals                            6-15
                    6.5.1.4 Organic Compounds                               6-15
             6.5.2  Potential Receptors                                        6-16
                    6.5.2.1   Ecological Receptors                              6-16
                    6.5.2.2   Human receptors                                 6-17
             6.5.3  Potential Exposure Pathways                               6-17
             6.5.4  Conceptual Model of Potential Risk for Ocean Outfalls       6-18
       6.6    Risk Analysis of Ocean Outfalls                                   6-21
             6.6.1  Evaluation of Physical Transport                           6-21
                    6.6.1.1   Transport, Dispersion and Dilution by Currents      6-22
                                       IV

-------
                    6.6.1,2 ._ Dilution of the Effluent Plume                     6-23
             6.6.2  Evaluation of Stressors, Exposure Pathways and Receptors    6-28
                    6.6.2.1  Pathogenic Microorganisms                       6-28
                    6.6.2.2  Nutrients                                        6-32
                    6.6.2.3  Metals and Organic Compounds                    6-37
                    6.6.2.4  Toxicity Testing of Effluent                       6-40
             6.6.3  Final Conceptual Model of Probable Risk for Ocean Outfalls  6-41
       6.7    Potential Effects of Data Gaps                                     6-45
       References                                                             6-46

7.0    DISCHARGE TO SURFACE WATERS                                 7-1
       7.1    Definition of Discharge to Surface Waters                           7-1
       7.2    Use of Discharge-to-Surface-Waters Option in South Florida          7-1
       7.3    Environment Into Which Treated Wastewater is Discharged           7-2
             7.3.1   Estuarine Environments                                     7-2
                    7.3.1.1  Tampa Bay                                       7-3
                    7.3.1.2  Sarasota Bay                                      7-3
                    7.3.1.3  Indian River Lagoon                               7-4
                    7.3.1.4  Florida Bay                                       7-4
             7.3.2  Fresh Water Environments                                  7-5
       7.4    Option-Specific Regulations and Requirements                      7-7
             7.4.1   Treatment and Disinfection Requirements                     7-7
             7.4.2   Standards for Surface-Water Quality                         7-8
       7.5    Problem Formulation                                             7-10
             7.5.1   Potential Stressors                                        7-10
                    7.5.1.1  Nutrient Stressors                                 7-11
                    7.5.1.2  Metals                                           7-12
                    7.5.1.3  Organic Compounds                              7-12
                    7.5.1.4  Pathogenic Microorganisms                        7-13
                    7.5.1.5  Secondary Stressors                               7-13
             7.5.2   Potential Receptors and Assessment Endpoints               7-15
             7.5.3   Potential Exposure Pathways                               7-15
             7.5.4   Conceptual Model of Potential Risk for the
                       Discharge-to-Surface-Waters Option                     7-16
       7.6    Risk Analysis of the Discharge-to-Surface-Waters Option            7-17
             7.6.1  Evaluation of Stressors and Assessment Endpoints            7-19
                    7.6.1.1   Nutrients                                        7-19
                    7.6.1.2  Metals                                           7-20
                    7.6.1.3   Organic Compounds                              7-20
                    7.6.1.4  Pathogenic Microorganisms                        7-21
             7.6.2  Evaluation of Receptors and Exposure Pathways              7-21
       7.7    Final Conceptual Model of Discharge-to-Surface-Waters Option      7-24
       7.8    Gaps in Knowledge                                               7-26
       References                                                             7-27
                                       v

-------
8.0   RELATIVE RISK ASSESSMENT
      8.1    Identified Risk Issues
             8.1.1  Wastewater Treatment and Disinfection
             8.1.2  Large-scale Transport Processes
             8.1.3  Distance and Time Separating Discharge Points and
                      Potential Receptors
             8.1.4  Attenuation Processes
             8.1.5  Factors that Contribute to or Diminish Risk
             8.1.6  Data and Knowledge Gaps
      8.2    Risk Issues Relevant to Human Health
      8.3    Risk Issues Relevant to Ecological Health
      8.4    Conclusion
      References
APPENDIX 1
APPENDIX 2
APPENDIX 3
APPENDIX 4
APPENDIX 5
APPENDIX 6
APPENDIX 7
APPENDIX 8
  8-1
  8-1
  8-8
  8-9
  8-9
 8-10
 8-11
 8-12
 8-12
 8-13
 8-22
 8-24
Al-1
A2-1
A3-1
A4-1
A5-1
A6-1
A7-1
A8-1
                                     VI

-------
                               LIST OF TABLES
 Table

 ES-10 Data and Knowledge Gaps                                           ES-23
 ES-11 Estimate of Risk to Human Health Associated with
          Each Wastewater Disposal Option                                 ES-24
 ES-12 Estimate of Risk to Ecological Health Associated with
          Each Wastewater Disposal Option                                 ES-25
 2-1    Wastewater Treatment Plants Discussed in This Report                     2-3
 2-2    Typical Levels of Constituents in Wastewater and Percent
          Removal Using Treatment (Primary and Secondary)                    2-13
 2-3    National Standards for Secondary Treatment                              2-14
 3-1    Representative Human Health and Ecological Stressors
          Selected for this Study                                               3-8
 3-2    Microbial Pathogens Potentially Present in Untreated
          Domestic Wastewater                                               3-9
 4-1    Dade County - Representative (Weighted Average) Hydraulic
          Conductivity, Porosity and Thickness of Hydrologic Units               4-9
 4-2    Pinellas County - Representative (Weighted Average) Hydraulic
          Conductivity, Porosity and Thickness of Hydrologic Units              4-10
 4-3    Brevard County - Representative (Weighted Average) Hydraulic
          Conductivity, Porosity and Thickness of Hydrologic Units              4-11
 4-4    Concentrations of Representative Organic and Inorganic Stressors           4-25
 4-5    Representative Pathogenic Stressors                                     4-26
 4-6    Pressure Head from Buoyancy and Injection (Scenario 1)                   4-37
 4-7    Pressure Head from Buoyancy and Injection (Scenario 2)                   4-37
 4-8    Times of Travel to USDWs and Hypothetical Receptor Wells               4-38
 4-9    Estimated Horizontal Travel Distances                                   4-39
 4-10   Range of Travel Times to Hypothetical Receptor Wells                    4-42
 4-11   Concentrations of Representative Stressors at USDWs and
          Hypothetical Wells                                                 4-44
 4-12   Assumptions Used for Florida DEP's Human Health Risk
          Assessment for Reuse                                               4-48
 4-13   Coliform Standards                                                    4-49
 4-14   Pathogen Concentrations in Water Corresponding to 1 x 10-4 Risk           4-50
 4-15   Microbial Transport in Aquifers                                         4-51
4-16   Survival of Microorganisms in Water                                    4-53
4-17   Inactivation Rates for Microorganisms in Aquatic Media                   4-54
 5-1     Reclaimed Water Reuse Activities in Florida                               5-3
 5-2     Reuse Flows for Reuse Types by DEP District and Water
          Management Districts                                                5-4
5-3     Effluent Travel Times in the Surficial Aquifer                             5-17
5-4     Initial Concentration of Representative Stressors in Reclaimed Water        5-18
5-5     Contaminant Transport and Fate in the Surficial Aquifer                    5-20
5-6     Comparison of Cryptosporidium Concentrations in the Environment         5-23
6-1     Characteristics of Southeast Florida Ocean Outfalls                         6-1
                                      vn

-------
6-2    Federal and Florida Class III Water Quality Criteria and Guidance
          Values for the Indicator Bacteria Groups                              6-10
6-3    Typical Concentrations of Fecal Indicator Bacteria in
          Raw Untreated Sewage                                             6-14
6-4    Average Current Speeds (cm/sec)                                       6-23
6-5    Flux-Averaged Initial Dilution of Effluent Plume                         6-24
6-6    Recommended Mixing Zone Ranges for Unchlorinated Effluent,
          Using Different Methods of Calculating Bacterial Concentrations        6-29
6-7    Maximum Allowable Concentrations of Indicator Bacteria in Effluent
          within Different Mixing Zones                                      6-30
6-8    Comparison of Circular Mixing Radii for Effluent and Outfall
          Distance from Shore                                                6-31
6-9    Nutrient Concentrations in Secondary Treated Effluent, Ambient Water,
          and in the 400 m and 800 m Mixing Zones for Three Ocean Outfalls     6-33
6-10   Priority Pollutant Metals Detected in Treated Wastewater Effluent
          Exceeding Class III Marine Water Quality Standards                   6-38
6-11   MBAS Concentrations in Effluent and Calculated Dilution
          Concentration at 400 Meters from the Boil                            6-40
7-1    Criteria for Surface-Water Quality Classifications                           7-9
8-1    Relevant Risk Assessment Issues for the Four Wastewater
          Management Options                                                 8-2
8-2    Relevant Issues for Human Health                                       8-13
8-3    Relevant Issues for Ecological Health                                    8-19
                                      vni

-------
                               LIST OF FIGURES
ES-1  Municipal Wastewater Treatment Plants in South Florida                  ES-2
ES-2  Use and Disposal of Effluent and Reused Water in Florida                 ES-3
ES-3  Wastewater Management for Selected Counties in South Florida            ES-4
ES-4  Levels of Treatment and Disinfection for the Four Disposal Options         ES-5
ES-5  Conceptual Model of Potential Risks for the Deep-Well
          Injection Option                                                   ES-7
ES-6  Hydrologic Profile of South Florida Aquifer System                       ES-8
ES-7  Representative Hydrogeologic Cross Sections                            ES-9
ES-8  Migration of Wastewater by Bulk Flow from a Deep-Well
          Injection Zone                                                    ES-12
ES-9  Effluent Plume Characteristics for Ocean Outfalls                        ES-17
1-1    The South Florida Study Area                                             1-3
2-1    Municipal Wastewater Treatment Plants in South Florida                    2-2
2-2    Wastewater Management Options and Design Capacities for
          Counties in South Florida                                             2-4
2-3    Hydrologic Profile of South Florida Aquifer System                         2-9
4-1    Locations of Class I Injection Wells in South Florida                        4-2
4-2    Representative Hydrogeologic Cross Sections                               4-5
4-3    Geologic Profile of South Florida                                         4-7
4-4    Fluid Movement Associated with Class I Deep Well Injection
          Facilities in South Florida                                           4-13
4-5    Conceptual Model of Potential Risks for the Deep Well Injection Option     4-23
4-6    Migration Following Deep Well Injection; Fluid Through Porous
          Media (Scenario 1)                                                 4-31
4-7    Migration Following Deep Well Injection; Bulk Flow Through
          Preferential Flow Paths (Scenario 2)                                 4-33
4-8    Final Concentrations of Representative Stressors Versus Time              4-61
5-1    Conceptual Model of Potential Risks for the Aquifer Recharge Option       5-15
6-1    Locations of Ocean Outfalls in Southern Florida                            6-2
6-2    Effluent Plume Characteristics for Ocean Outfalls                           6-4
6-3    Circulation Characteristics of the Western Boundary
          Region of the Florida Current                                         6-7
6-4    Conceptual Model of Potential Risks for the Ocean Outfall Option          6-20
6-5    Initial Dilution as a Function of Current Speed and Discharge Rate
          (Miami-Dade Central Outfall)                                       6-26
6-6    Total Physical Dilution as a Function of Distance from the Boil
          (Four Ocean Outfalls)                                              6-27
7-1    Conceptual Model of Potential Risks for the Surface Water Option          7-18
                                       IX

-------
[ This page intentionally left blank ]

-------
 Executive Summary

 WASTEWATER CHALLENGES IN SOUTH FLORIDA

 Every day, more than 1.5 billion gallons of wastewater leave municipal treatment
 facilities in Florida bound for reuse or disposal. Municipalities in South Florida rely less
 on discharges to surface waters and more on reuse, ocean discharge and deep-well
 injection. For example, in Miami-Bade County, for every three gallons of wastewater
 generated,  one gallon is treated and sent to deep underground saltwater formations. The
 other two gallons are piped out to the ocean, three and a half miles offshore. In dry-
 weather conditions in Pinellas County, for every three gallons of wastewater generated,
 all three gallons are reclaimed to golf courses, parks, and lawns after high-level treatment
 and disinfection. However, the Pinellas area receives on average forty-eight inches of rain
 annually, and deep-well disposal is heavily relied on as the backup during wet weather.

 Each municipality in South Florida is faced with its own particular challenges to ensure,
 safe reuse and disposal  of wastewater, safe drinking water and a healthy environment for
 its 5.8 million residents. Local municipalities are struggling to make sound wastewater
 management decisions, taking into account the often overwhelming complexities and the
 range of technical issues associated with different reuse and disposal options.

 The State is strongly committed to protecting its surface waters, such as lakes, rivers,
 streams, wetlands, estuaries, and the ocean.  It is equally committed to protecting the
 highly permeable aquifer systems that provide 94% of the area's drinking water. A major
 challenge to protecting  water resources is Florida's growing population and the
 accompanying need for safe drinking water, safe reclaimed water reuse, and safe
 wastewater disposal.

 The Environmental Protection Agency (EPA) has established minimum requirements for
 Class I municipal wells and other underground injection activities through a series of
 Underground Injection  Control (UIC) regulations at Code of Federal Regulations (CFR)
 Title 40 Parts 144-147,  developed under the authority of the Safe Drinking Water Act.
 These regulations ensure that Class I municipal wells will not endanger USDWs by
prohibiting the movement of any contaminant into Underground  Sources of Drinking
 Water (USDW).

 On July 7, 2000, EPA proposed revisions to the UIC regulations that would allow
 continued wastewater injection by existing Class I municipal wells that have caused or
 may cause movement of contaminants into USDWs in specific areas of Florida (65 FR
 42234). Continued injection would be allowed only if owners or operators meet certain
 requirements that provide adequate protection for USDWs. In the alternative, if new
requirements are not promulgated, owners and/or operators of wells targeted by the
proposal would be required to close their wells  and adopt different wastewater disposal
practices, which could consist of surface water disposal, ocean outfall, and/or reuse. Use
of these alternative disposal practices would likely require the construction of systems for
advanced wastewater treatment, nutrient removal, and high-level disinfection.
                                      ES-1

-------
CONGRESSIONAL MANDATE FOR RELATIVE RISK ASSESSMENT

EPA, as directed by congressional language in its fiscal year 2000 appropriation,
prepared the relative risk assessment presented in thisteport:

    Within available funds, the conferees direct EPA to conduct a relative risk assessment
    of deep well injection, ocean disposal, surface discharge, and aquifer recharge of
    treated effluent in South Florida, in close cooperation with the Florida Department of
    Environmental Protection [DEP] and South Florida municipal water utilities.

Congress directed EPA to conduct this assessment because wastewater injected into deep
wells had moved from  where it was supposed to be confined to areas where it is
prohibited. Congress directed EPA to conduct the relative risk assessment to shed light on
the risks posed by fluid movement from deep injection and relate those risks to  risks
posed by treated effluent from  other wastewater management options.

MUNICIPAL WASTEWATER TREATMENT OPTIONS IN SOUTH FLORIDA

To capture all counties with deep-well  injection, the South Florida area considered in the
relative risk assessment extends south from a line drawn from the northern end  of
Brevard County on the east coast to the northern end of Pinellas County on the west coast
(Exhibit ES-1).
                                                             [Browanj tjgunly North S»a|ongiWWTp ]
Exhibit ES-1. Municipal Wastewater Treatment Plants in South Florida
                                     ES-2

-------
Wastewater Treatment Options

Florida primarily uses four options for the management of treated municipal wastewater
(Exhibit ES-2):
    •  Deep-well injection: Wastewater is injected by gravity flow or under pressure
       into deep geological strata below USDWs. Under EPA and State UIC program
       regulations Class I wells inject fluids beneath the lowermost formation containing
       a USDW.
    •   Aquifer recharge: Reclaimed water is discharged to land application systems,
       such as infiltration basins and unlined ponds.
    •   Discharge to ocean outfalls: Treated wastewater is discharged to the ocean via
       outfall pipes that may extend from almost 1 mile to more than 3.5 miles from
       shore.
    •   Discharge to surface-water bodies: Wastewater is discharged into canals,
       creeks, and estuaries.
                                          21%
         20%
• Deep Well Injection
  (320 mgd)

H Reuse
  (580 mgd)

m Ocean Outfall
  (310 mgd)

H Surface Water Discharge
  (340 mgd)
Exhibit ES-2. Use and Disposal of Effluent and Reused Water in Florida1
Although the term option, used to describe the wastewater treatment methods, suggests
any of these are available for use by municipalities in South Florida, in fact most
municipalities are limited by a variety of critical local conditions, governing regulations
and costs in evaluating possible treatment methods. (Exhibit ES-3).
1 This chart uses data for the entire state of Florida. No specific data was available for the study area only.
The distribution of waste treatment options within the study area is likely to be different than that presented
in this chart (i.e. all ocean disposal and deep underground injection is in the Study area and there is much
less use of suiface water disposal in South Florida).
                                       ES-3

-------
                                                                 (Deep
                                                                  Wells
                                                                 (Reuse
                                                                 I Ocean
                                                                 Outfalls


                                                                 [Surface
                                                                 Water
                                                                 Discharge
            B reward
                       Dadc
Hlllsborough   Pinedas
                                                    Sarasota
Exhibit ES-3. Wastewater Management for Selected Counties in South Florida
Levels of Wastewater Treatment and Disinfection

Wastewater treatment facilities in South Florida combine various levels of wastewater
treatment and disinfection to arrive at effluent concentrations that are appropriate for the
local conditions and that comply with State and EPA requirements.

  •   Primary Treatment is a basic treatment process that removes material that will
     float or settle.
  •   Secondary Treatment is a process in which bacteria consume the biodegradable
     organic matter and remove suspended solids using chemical and biological
     processes. The success of treatment may be quantified by its ability to remove
     Biochemical Oxygen Demand (BOD) and Total Suspended Solids (TSS).
  •   Reclaimed Water in Florida means water has received at least secondary treatment
     and is reused. Some uses require high-level disinfection that includes filtration.
  •   Advanced Water Treatment (AWT) refers to treatment beyond secondary but in
     Florida it has specific regulatory meaning for a combination of treatments that
     includes secondary treatment, high-level disinfection, nutrient removal, and
     removal of toxic compounds (usually by filtration). AWT is used if there are
     requirements to remove specific components, such as  nitrogen and phosphorus,
     which are not removed by secondary treatment alone.

  *   Disinfection is the selective destruction of pathogens.  The State regulations define
     basic, intermediate and high-level disinfection with levels of filtration and bacterial
     deactivation.

Each of the four wastewater management options (deep-well injection, ocean outfall,
aquifer recharge, and surface water discharge) provide different levels of treatment and
disinfection, depending upon regulatory and site-specific needs. The levels for
Biochemical Oxygen Demand, (BOD), Total Suspended Solids (TSS), Total Nitrogen
(TN), and Total Phosphorus, (TP) shown in Exhibit ES-4 are required for some required
discharges and do not apply universally to  all (see Chapters 62-600 and 62-610 F.A.R.).
                                      ES-4

-------
           Deep Well
            Injection
          No disinfection
        achieves 20-20 mg/L
           of BOD-TSS
Secondary
Treatment


Basic
Disinfection
^
Ocf
f-
:an
Outfall
Basic disinfection
chieves 30-30 mg/L
of BOD-TSS

Filtr
ition
s /
High-Level
Disinfection
/ /
^
t
     Aquifer
    Recharge
 High-level disinfection
achieves 5-5-10-1 mg/L
  ofBOD-TSS-TN-TP
  Discharge to
 Surface Water
High-level disinfection
achieves 5-5-3-1 mg/L
 of BOD-TSS-TN-TP
Exhibit ES-4. Levels of Treatment and Disinfection for the Four Disposal Options
RISK ASSESSMENT

Risk assessment is a multistep process. It evaluates the likelihood that adverse human
health or ecological effects will occur as a result of exposure to stressors. A stressor is
any physical, chemical, or biological entity that can induce an adverse response. The
organism, population, or ecosystem exposed to a stressor is referred to as a receptor.
Exposure refers to the contact or co-occurrence of a stressor and receptor. If there is no
contact or co-occurrence between the stressor and the receptor, then there is no risk.

Risk characterization is the culminating step of the risk assessment process. It conveys
the risk assessor's judgment about the existence of human health or ecological risks and
their nature (US EPA, 2000). Information from the risk assessment steps is integrated and
synthesized into an overall conclusion about risk that is informative and useful  for
decision-makers and for interested and affected parties.
                                        ES-5

-------
Approach Used in This Relative Risk Assessment

The risk assessment conducted by EPA involved investigating four very different
wastewater disposal options: deep-well injection, aquifer recharge, discharge to ocean
outfalls, and discharge to surface-water bodies. Each option has its own specific stressors
(hazards), exposure pathways, receptors, and effects.

Data from many sources were used to support the analyses and evaluations. Risk
characterization for each wastewater treatment option included identifying and describing
the associated risks, the potential magnitude of the risks, and potential effects on human
and ecological health. The relative risk assessment then described and compared risks for
all four wastewater management options.

This relative risk assessment first used a generalized approach to describe potential risks
and identify possible stressors, sources, exposure pathways, and effects on receptors. This
step incorporates human health and ecological risk components and provides a
conceptual model of potential risk. A conceptual model was developed for each of the
four disposal options. Exhibit ES-5 is an example of a conceptual model of potential risks
developed for the relative risk assessment. Potential system stressors, exposure pathways,
receptors, and the potential effects on receptors are identified in the model.

To assess the risks and to allow comparisons, EPA conducted individual risk assessments
for each wastewater disposal option, and the risks associated with each were
characterized. The risks  and risk factors identified in each disposal option were then
evaluated and described. The overall comparisons and conclusions are presented as
relative risk assessment matrices. EPA found that the parameters that are relevant to one
particular disposal option are not necessarily  relevant to the remaining three. Therefore, a
strictly quantitative comparison between the four options was not feasible.
                                       ES-6

-------
      Primary
      Source
    Potential
System Stressors
Pathways / Processes
Waste Water Treatment
   Ptant Discharge
                        Inorganic
                        Constituents
                       Volatile Organic
                       Constituents
                      Syrtnetjc Organic
                      Constituents  -
                       Microbiological
                       ' Constituentsn
                        Miscellaneous
                       'Constituents
                     Physical Processes
                        Ground Water Flow:
                         1. Conventional Porous
                          Media Flow
                        2. Bulk Flow through
                          Preferential Flow Paths
                        Dilution due to Advection
                        and Diffusion
                        Adsorption / Desorption
                        Mechanical Failure of
                        Injection System
                     Chemical Processes
                        Precipitation / Dissolution
                        Oxidation / Reduction
                        Chemical Transformation
                        Complex Formation
                     Biological Processes
                      Biogeochemical Transformation
                      Growth
                      Biodegradation
                      Microbial Inactivation
 Potential Receptors
USDW
Drinking Water Weils
 (Municipal and Private)
Irrigation Welts
Surface Water
 Phyto plankton and Zoopiankton
 Submerged Aquatic Vegetation (SAV)
 Macro-invertebrates
 Fish
 Aquatic and Terrestrial Birds
 Aquatic and Terrestrial Mammals
 Reptiles and Amphibians
 Endangered Species
 Humans
                           Potential Effects
                          Ecological
                           Eutrophfcation (excess nutrients and algal
                              growth, low oxygen)
                           Harmful Alga} Blooms (HABs)
                           Changes in Phytoplanklon and Zoopfankton
                              Communities
                           Toxic Effects on Aquatic and Terrestrial
                              Species
                           Developmental or Reproductive Changes in
                              Aquafic or Terrestrial Organisms
                           Reduced Growth of SAV due to Reduction
                              in Water Clarity
                           Food Web Effects
                          Human Health
 Exhibit ES-5. Conceptual Model of Potential Risks for the Deep-Well Injection
 Option
 DEEP-WELL INJECTION

 In South Florida, the most common means of disposal for treated municipal wastewater is
 by deep-well injection. Deep wells typically inject at depths ranging from 650 to greater
 than 3,500 feet below land surface, depths that are considerably deeper than the aquifers
 used for drinking-water supply wells. However, it is acknowledged that in some parts of
 South Florida, injected water has moved upward into overlying layers and, in some cases,
 into the base of the area designated as the  underground source of drinking water
 (USDW).

 The Upper Floridan Aquifer and the Biscayne Aquifer are the main water sources in the
 South Florida region (Exhibit ES-6). The Floridan Aquifer is extensive and underlies
 parts of Alabama, southeastern Georgia, southern South Carolina, and all of Florida. It is
 divided into the Upper Floridan and Lower Floridan aquifers, which are separated by a
 middle confining unit.
                                               ES-7

-------
                     UNNAMED
                     SURFICIAL.
                   AQUIFERS AND
                   INTERMEDIATE
                     AOUIFfiflS,
                  UNDIFFERENTIATEO
                                                      NAPLES
                         East

                            A'
                     ATLANTIC
                      OCEAN
       BIG CYPRESS   THE   \
         SWAMP  EVERGLADES \
                                                            SURFICIAL AQUIPBR
                                                                SYSTEM

                                                        INTERMEDIATE AQUIFER SYSTEM
                                                              (zona of low yield)
  Raise from U.S Geological Survey digital daia, 1:2,000,000. 197B
  Atrjors Eguai-Aroa Conic projection
  Siandard Parallels 29'30' and 45' 30', central fneridan -ay 00'
        50 MILES    VERTICAL SCALE
1—1	J	1      BREATI.Y EXAGGERATED
                                                                        Source: McPrterson el al (2000)
Exhibit ES-6. Hydrologic Profile of South Florida Aquifer System
In the southeastern part of South Florida, the Floridan Aquifer is overlain by a relatively
shallow surficial aquifer, the Biscayne Aquifer. In general, the surficial aquifer is
composed of relatively thin layers of sands with some interbedded shell and limestone
(Exhibit ES-6). The surficial aquifer in Pinellas County is only about 56 feet thick; in
Brevard County, it is only 110 feet thick (Exhibit ES-7). The underlying intermediate
confining unit, which separates the surficial and Upper Floridan aquifers, is also
relatively thin (about 219 feet thick in Pinellas County and 210 feet thick in Brevard
County). These hydrogeologic characteristics mean that the surficial aquifer yields only
small amounts of water. Thus, it is not a major source for public water supply, although it
is used extensively for private water supplies. However, in southeastern Florida, the
Biscayne Aquifer is the principal source of drinking water. In this area, both the  aquifer
and the underlying intermediate confining unit are thicker (more than 230 and 610 feet
thick, respectively), which results in an  increased water-bearing capacity.
                                          ES-8

-------
w
                  Intennwfiiti
             Shallow  Monitoring
           Monitoring —,   «*«    Deep
              WM I
        2000-
                                                                         Dade County, Florida
Brevard County, Florida
         Exhibit ES-7. Representative Hydrogeologic Cross Sections

-------
The presence of the separating confining units (intermediate and middle), combined with
the considerable depth to the deep-well injection zones, was considered to provide a
sufficient level of protection to the water-bearing strata that supply public water.
However, the relative safety of this disposal option is now in question because injected
water is known to have migrated up to and, in some cases, into the USDWs.

Deep-well injection fluid is given a secondary level of treatment and the State does not
require disinfection, although some facilities may dispose of excess (unused) reclaimed
wastewater using Class I deep-well injection. Treatment beyond a secondary level is used
to varying degrees in the three other disposal options included in the risk assessment
(aquifer recharge, discharge to ocean outfalls, and discharge to surface-water bodies)
(Exhibit ES-4).

Many parts of the United States use Class I injection wells for disposal of hazardous and
nonhazardous fluids. In Florida, deep-well (Class I) injection is an important
management option for treated municipal wastewater and accounts for approximately
20% (0.44 billion gallons per day) of the State's wastewater management capacity
(FDEP, 1997). Most of this use occurs in South Florida, particularly southeastern Florida
and in coastal areas. The wells inject large volumes of wastes into deep  rock formations,
which are required to be separated from sources of drinking water by layers of
impermeable clay and rock.

The use of Class I wells in South Florida has been considered a safe and effective means
of disposing of treated wastewater. However, ground-water monitoring  data has indicated
that, at some facilities, wastewater is not being adequately confined, resulting in
unintended movement of the injected fluid into USDWs.  At some locations, injected
wastewater has migrated from the injection zone into overlying layers and is
compromising USDWs. Of 93 facilities with deep injection wells in South Florida, 18
have been identified as having unintended  movement of fluid out of the injection zone: 3
have confirmed fluid movement into the USDW, 6 are reported to have  probable
movement into the USDW, and 9 have  movement into non-USDWs, (layers overlying the
injected zone but below the USDW).

Regulatory Oversight of Deep-Well Injection

Federal and State regulations govern the siting, construction, operation,  and management
of Class I injection wells. A key U1C regulatory requirement prohibits the movement of
any contaminant from a Class I injection well into a USDW. UIC regulations also specify
well siting requirements, including specifications for constructing wells, for defining
hydrologic conditions relative to the site, for ensuring the mechanical integrity of
injection wells, and for proper operation and maintenance of wells. Class I injection wells
must be cased and cemented to prevent the movement of fluids into or between USDWs.
Injection pressures may not cause fractures in the confining zone or cause the movement
of injection or formation fluids into a USDW. (40CFR146.12 and 13). In addition, the
State requires that all Class I municipal waste disposal wells provide, at a minimum,
secondary treatment.
                                     ES-10

-------
 In spite of these many regulations and controls, unintended migration of injected
 wastewater in South Florida has occurred. Therefore, the ability to maintain sufficient
 confinement between the injection zone and the USDW is in question.

 Option-Specific Risk Analysis for Deep-Well Injection

 The risk analysis of deep-well injection focused on Brevard, Pinellas, and Dade counties,
 because these counties are geographically representative (i.e. they are located in the three
 corners of the assessment area) and fluid movement, to some degree, has occurred in each
 location. A large volume of treated wastewater is injected into Class I injection wells.
 Subsequent migration of this wastewater and any dissolved or entrained wastewater
 constituents that remain after treatment can lead to exposure for receptors such as
 USDWs and water-supply wells.

 Secondary treatment of wastewater with no disinfection does not remove all potential
 stressors to human health. Nitrate levels can exceed the Federal and State maximum
 contaminant level (MCL) for drinking water; pathogenic bacteria and viruses are not
 inactivated and may exceed standards for drinking water; and Giardia and
 Cryptosporidium levels may exceed Florida's health-based (reuse) recommended criteria.

 Stressors to ecological health that may remain after treatment are generally limited to
 nitrates and phosphates.  These are considered nutrients for ecological systems. When
 present in excess concentrations, they can destabilize the natural systems and cause
 eutrophication of aquatic systems. Given this characterization of the level of
 contaminants remaining in secondary treated effluent, a next step  in the risk assessment
 was to examine the fate and transport of these contaminants in the sub-surface.

 How Injected Wastewater Can Reach Drinking-Water Supplies

 In general, injected wastewater can move upwards by porous media flow and by bulk
 flow. These represent two extremes: porous media flow is a slow fluid movement through
 connected pores in the rock matrix, and bulk flow is a more rapid flow through
 preferential paths, such as fissures, fractures, caverns, or channels (Exhibit ES-8). Bulk
 flow can also occur from improperly constructed and poorly maintained injection-well
 systems that lead to an incomplete seal between the well and its casing.

In most cases in South Florida, both porous flow and bulk flow mechanisms will
 contribute to upward migration. However, it is not possible to differentiate the
 contribution of each for a given location.  Bulk flow is likely a major contributing process
 in South Florida, where there are karst geologic features. The most well known geologic
feature in the area that can support bulk flow is the Boulder Zone. Located in the middle
 section of the Lower Floridan Aquifer (Exhibits ES-7 and ES-8), this highly developed
and complex fracture zone has extensive cavernous pores, fractures, and widened joints
that allow channelized groundwater flow, sometimes at extremely rapid rates.
                                      ES-11

-------
M
                    Initial Injection
Initial Migration with
 Ground Water Flow
Vertical Migration Due to
   Injection Pressure
    and Buoyancy
Continued Vertical and
 Horizontal Migration
           Boulder
           Zone
                                                I Ground Waler Flow Direct!
                                                                                  Ground Water Flow Drectio
                                                                                                                   
-------
Fluid movement underground is influenced by several factors. Temperature and density
differences between native and injected waters affect buoyancy. The fluid density of
injected wastewater is roughly equivalent to fresh water. However, wastewater is injected
at depths where the native groundwater is saline or hypersaline. Buoyancy tends to force
the comparatively lighter, less dense wastewater upward.

Injection pressure also influences fluid movement, but the degree of influence is affected
by the geology. In parts of South Florida, where injection zones demonstrate a great
capacity to accept injected fluid (for example, the Boulder Zone), the influence of
injection pressure may be less significant. Regional differences in the effect of injection
pressure were accounted for in the risk analysis by including Dade, Brevard, and Pinellas
counties.

The exposure pathway for the stressors found in injected wastewater is upward migration
of the injected wastewater into the base of USDWs. In some locations, this upward
migration can occur relatively rapidly and with little dilution of stressors. In the area of
the Boulder Zone, injected wastewater that has migrated upwards might pose some
ecological health risk for the marine environment, were the fluid to migrate more than
2500 feet upward . There  is little information currently available to assess such a risk.

Human Health and Ecological Risk Characterization of Deep-Well Injection

Deep-well injection for disposal of treated municipal wastewater has resulted in fluid
movement into USDWs. In both Pinellas County and Dade County fluid has moved into
the USDW.

The overall human health risk is lower for those USDWs that are deep, and exposure to
stressors for currently used drinking-water sources is less likely. The current risk of
human exposure is considered lower for Dade and Brevard counties, because the length
of time required for contaminants to reach current drinking water supplies is long.
However, the time of travel in the Pinellas County area is shorter because of the
shallower aquifer depth and lack of confinement. The risk would be therefore higher for
Pinellas County and exposure of current water supplies to stressors more likely but for
the fact that Pinellas County effluent is subjected to high level disinfection. Failures
within the injection system itself clearly increase risk. Improperly constructed or poorly
maintained injection-well systems can result in decreased times of travel to receptors and
in an associated increase in risks and exposures. However, there is no information to
conclude that mechanical  failures of Class I municipal waste disposal wells in South
Florida have resulted in significant fluid movement into USDWs.

Ecological risk can result  from nutrient enrichment of surface waters and the associated
ecosystems. However, in South Florida, the risk is considered low because that
movement is unlikely. There may be an increased risk in situations where fluid migrates
rapidly to surface-water bodies, as in a conduit or a bulk-flow scenario. Nutrient
enrichment and other potential impacts to near-shore marine and estuarine environments
could occur under such a scenario.
                                      ES-13

-------
AQUIFER RECHARGE

Any practice that potentially results in the replenishment of a groundwater aquifer can be
considered aquifer recharge. Treated municipal wastewater discharged onto the land may
percolate through soils and underlying geologic media until it reaches and recharges the
surficial aquifer. In Florida, several practices may be considered as aquifer recharge:
irrigation, discharge to infiltration basins or absorption fields, and discharge to wetland
treatment systems. The State defines reclaimed water as water that has received, at least,
secondary treatment and disinfection and is reused after flowing out of a domestic
wastewater treatment facility. Reuse is the deliberate application of reclaimed water for a
beneficial purpose according to Florida requirements. The final use of the wastewater
determines the specific treatment requirements.

Reuse of water for irrigation is significant in Florida. Of a total of 359 reuse irrigation
systems, approximately one-half (179) are golf-course irrigation systems, while the other
half is divided among irrigation for other public-access areas (98) and residential
irrigation (82). Agricultural irrigation systems using reclaimed water number 117.

Reclaimed water is discharged at a rate that prevents surface runoff or ponding and that is
within a designated hydraulic loading rate. Loading rates are based on the ability of the
plant and soil system to remove pollutants from the reclaimed water, the infiltration
capacity, and the hydraulic conductivity of the underlying geology. Slow-rate land
application systems must have back-up disposal methods, such  as discharge to a storage
area or to deep-well injection, for wet-weather conditions and when water-quality
treatment standards are not met.

Rapid-rate land application systems discharge reclaimed water to rapid infiltration basins
or absorption fields. Infiltration basins operate in series and may include subsurface
drains that receive and distribute the water. Absorption fields are subsurface absorption
systems covered by soil and vegetation and may include leaching trenches, pipes, or other
conduits that receive and disperse water. Rapid-rate systems are potentially high-volume
systems. Because of the increased percolation, the loading rates are higher than  for slow-
rate land application, and rapid-rate systems do not require wet-weather  alternatives. For
these reasons, EPA focused on rapid-rate infiltration basins (RIBs) for the risk
assessment.

Regulatory Oversight of Aquifer Recharge

Aquifer recharge as a wastewater management option is not specifically  regulated, but
the State regulates the reuse of reclaimed water and land application. State regulations
specify  system design and operating requirements. Backup treatment and holding
capacity is required, in case of system interruption. Slow-rate land application must have
back-up wet-weather disposal options. Wastewaters must meet water-quality criteria and
must be tested for pathogenic protozoans. Setback distances from surface waters and
from potable water sources are required, and Florida's wastewater-to-wetlands rule
controls the  quantity and quality of treated wastewater discharged to wetlands.
                                      ES-14

-------
 Option-Specific Risk Analysis for Aquifer Recharge

 Rapid-rate systems have the potential of discharging large volumes of treated wastewater
 directly to the surficial aquifer. The public water supply in South Florida is generally
 drawn from wells about 250 feet deep and located in the surficial aquifer. In Pinellas
 County, the surficial aquifer is shallow, with a depth of about 56 feet. In Brevard County,
 the surficial aquifer extends to a depth of 110 feet. In Dade County, the surficial Biscayne
 Aquifer extends to a depth of 230 feet. Depending upon local groundwater conditions,
 rapid transport of reclaimed water to these shallow aquifers and current drinking water
 sources may occur. Similarly, surface-water bodies that are under direct influence of
 groundwater can be exposed to stressors in the discharged wastewater.

 Reclaimed water that is bound for rapid-rate land application must have undergone
 secondary treatment and basic disinfection, and rapid-rate systems must meet, at the base
 of the discharge zone, groundwater criteria. Projects with permit applications after
 January 1, 1996 must provide high level disinfection. As a result, the concentrations of
 stressors are considerably reduced. Potentially remaining stressors in reclaimed water
 include metals and other inorganic elements (for example, nitrate, ammonium,
 phosphate), volatile and synthetic organic compounds, and microorganisms resistant to
 high-level disinfection. Cyst-forming pathogenic protozoans, such as Cryptosporidium
 and Giardia, are resistant to chlorination and basic disinfection and require specialized
 filtration for removal. Concentrations of these pathogenic protozoans typically meet
 Florida's health-based (reuse) recommendations in rapid-rate land application waters, but
 some exceptions have been reported. The disinfection byproducts, trihalomethanes, can
 pose a human  health risk, but the concentrations in reclaimed water rarely exceed the
 health-based standards.

 Just as with deep-well injection waters, stressors to ecological health that may remain in
 reclaimed water after treatment are nitrates and phosphates. Because they are nutrients,
 they can destabilize the natural systems and, when present in excess concentrations, can
 cause eutrophication of aquatic systems. Thus, the next step of the risk assessment, the
 analysis of the fate and transport mechanisms and a determination of the time of travel,
 was very important.

 The time of travel for discharged effluent to move in groundwater to a receptor is site-
 specific and dependent on required setback distances, location and distance to receptor
water-supply wells, direction of groundwater flow, the actual distance to potential
receptor wells, and the aquifer's groundwater flow characteristics.

Natural attenuation processes were also analyzed to determine their affect on final
 constituent concentrations. Sorption, biological degradation, and chemical transformation
of constituents can reduce their overall concentration during transport in groundwater.
Rapid-rate infiltration and the associated shorter times of travel tend to limit natural
attenuation.
                                      ES-15

-------
Human Health and Ecological Risk Characterization of Aquifer Recharge

Because of the level of treatment, reclaimed water contains relatively few stressors,
which generally are at reduced concentrations. Many constituents remaining in the treated
wastewater are at levels that meet the respective drinking-water standards (MCLs). The
average concentrations of the cyst-forming Giardia protozoan meet risk-based criteria.
However, monitoring data from reuse facilities indicate the presence of Giardia in 58%
of the samples, with detections frequently exceeding the stated recommendation of 1.4
cysts per 100 milliliters.

Although time of travel may be relatively short for some locations and indicate a higher
potential risk, a high effluent transport rate does not result in a greater overall risk. Dade
County, where the Biscayne Aquifer has a high hydraulic conductivity, has the shortest
estimated travel times for treated effluent in groundwater to reach drinking-water supply
wells: 0.11 year for a 200-foot  setback, 0.28 year for a 500-foot setback, and 1.47 years
for a 2,640-foot setback. In spite of these relatively short times of travel, there is little
overall risk, because the final concentrations of stressors are below the respective
drinking water standards (MCLs).

DISCHARGE TO OCEAN OUTFALLS

Six publicly owned wastewater treatment facilities located in coastal southeastern Florida
currently use  ocean outfalls to dispose of treated municipal wastewater. The total volume
discharged is about 310 mgd. Before discharge, the wastewater undergoes secondary
treatment, followed by basic disinfection. The treated wastewater is discharged through
outfall pipes into the ocean at depths ranging from 27.3 to 32.5 meters and at distances
between 0.94 and 3.56 miles from shore.

The outfalls discharge into the  Florida Current, which flows northward to join the Gulf
Stream. Circulation created by  the Florida Current and associated eddy and rotary flows
is important and the western boundary of the current is a major nutrient source for ocean
productivity.  Effluent  discharged from the outfall forms a characteristic plume that tends
to rise in seawater because it is less saline. However, the effluent is rapidly diluted and
mixed with ocean water (Exhibit ES-9). The speed and direction of the currents are the
primary factors that govern plume dispersal.
                                      ES-16

-------


End of
Pipe .„
r Momentum

Displacement
Surfacing
Plume
(Boil)
Current
Displacement


                                                                 400m
                                                                Regulatory
                                                               Mixing Zone
                                                     Zone of Initial
                                                    Dilution Boundary
Exhibit ES-9. Effluent Plume Characteristics for Ocean Outfalls
The risk assessment for this option mainly focused on the potential effects on the marine
environment. Discharge to the ocean has no effect on sources of drinking water. The
receptors considered in this option are those that may have a direct exposure to seawater
containing effluent constituents.

Regulatory Oversight of Discharge to Ocean Outfalls

The Clean Water Act and Florida law require that municipal wastewater receive at least
secondary treatment before discharge to the ocean. When chlorine is used as a
disinfectant, it must be used at the minimum concentration necessary to achieve water-
quality standards. Higher concentrations of chlorine may lead to the production of
trihalomethanes, which are a human health risk.

State-designated Class III Waters are used for recreation and for the propagation and
maintenance of a healthy, well-balanced population offish and wildlife. Effluent
discharged into the ocean must meet the Class III standards for total suspended solids and
for a 5-day biological oxygen demand.

There are additional requirements for the effluent when it meets the receiving waters.
There are State and Federal water-quality criteria for effluent water at the end of the
                                      ES-17

-------
outfall pipe, within the mixing zone, and at the edge of the mixing zone. At the edge of
the mixing zone, Federal, State, and local regulations require that the water meet surface-
water quality standards.

Option-Specific Risk Analysis for Discharge to Ocean Outfalls

The focus of the risk analysis was the potential effects that discharges to the ocean may
have on ecological receptors. In Florida, ocean waters are not currently used as a source
for drinking water. Therefore, the ocean discharge option is not a human health risk
through the drinking-water supply. Human exposure to seawater that contains effluent
constituents may occur for recreational users (fishermen, boaters, and swimmers),
industrial fishermen, and outfall operators and workers. Exposure may be through dermal
contact, incidental ingestion of ocean water, ingestion of contaminated fish or shellfish
(near or removed from the point of discharge), or exposure to toxins produced by harmful
algal blooms. Ecological receptors include fish and other organisms that occur around the
ocean outfall discharge point as well as those that are removed from the outfall but may
be affected by the discharge.

Effluent constituents discharged to the ocean are those that typically remain after
secondary treatment and basic disinfection; nutrients, inorganic and volatile organic
compounds, synthetic organic constituents, metals, and microbial and miscellaneous
constituents. The use of disinfection in addition to  the secondary treatment reduces the
concentrations of the bacterial and viral stressors; however, the disinfection byproduct,
trihalomethanes, may occur. Trihalomethanes, a type of organic compound, can pose a
human health risk. Although information is lacking, they may also be a health risk to
marine life, such as marine mammals. Cyst-forming pathogenic protozoans, such as
Cryptosporidium and Giardia, are resistant to chlorination and require specialized
filtration for removal, and therefore, may be present as a stressor.

Potential receptors in the marine environment are numerous and range from submerged
aquatic vegetation, plankton (phytoplankton, zooplankton), and larger aquatic organisms,
including invertebrates,  fish, reptiles, birds, and marine mammals.

Inorganic constituents, such as nitrogen and phosphorus, and metals,  such as iron, are
nutrients. However, if they are overabundant, they become stressors.  In marine and
coastal environments, eutrophication can occur when excess nutrients are present. This
can produce harmful algal  blooms (red tides), change the natural phytoplankton
communities, destroy coral reefs, degrade sea grass and algal beds, and destabilize the
overall marine community structure.

Dilution and transport, which are controlled for the most part by ocean currents, are
important factors included in the risk analysis. Rapid dilution of effluent can reduce or
eliminate potential adverse effects on receptors. In addition, chemical and biological
processes that have the potential to affect the level of stressors were included in the risk
analysis.
                                      ES-18

-------
 Human Health and Ecological Risk Characterization of Discharge to Ocean Outfalls

 The risks associated with discharging effluent using ocean outfalls are low for both
 human and ecological receptors. There is no drinking-water receptors associated with
 ocean disposal and therefore, exposure through this pathway is unlikely.

 Effluent plumes are rapidly dispersed and diluted by the Florida Current, and flows
 towards coastal areas are infrequent because of the current's prevailing direction and
 speed. The concentrations of potential stressors in the effluent plume are low, because of
 the secondary treatment and disinfection, permit effluent concentration limits, and the
 subsequent dilution of the effluent after discharge. The distances of the outfalls from
 shore also decrease risk, with those more distant having the lowest risk. Outfalls that have
 multiport diffuser systems seem to further reduce risk by dispersing the effluent over a
 wider area further reducing concentrations of potential stressors.

 The treatment level used in ocean disposal does not remove certain pathogenic
 protozoans that could potentially affect human and ecological health. Pathogenic
 protozoans may pose a risk to marine mammals that come in contact with the effluent
 constituents. However, there is a lack of ecological health information on the effects of
 pathogenic protozoans, as well as other stressors, including metals, endocrine disrupters,
 and surfactants. Although the concentrations of these compounds may meet required
 water-quality standards, their effect on biological receptors at low concentrations is not
 understood. For example, endocrine disrupters operate at extremely low concentrations.

 Although chlorinated effluent meets water-quality standards generally within 400 meters
 of the outfall, the long-term ecological effects of discharging effluent  into the ocean are
 not understood. Currently, there are no long-term monitoring data available for these
 discharges to describe the ecological impacts or to determine what interaction there is, if
 any, between outfall constituent effects and terrestrial or coastal sources (such as
 pesticide runoff or river and groundwater inputs).

 DISCHARGE TO SURFACE WATERS

 Surface water disposal involves discharging treated wastewater directly into  canals,
 creeks, and estuaries that may be brackish, coastal/saline, or fresh water. The wastewater
 must receive at least secondary treatment and basic disinfection before discharge.
 Advanced wastewater treatment is required in some locations.

The use of this option in South Florida varies greatly. Treatment facilities in  Hillsborough
 County rely on this option for about 75% of their total design capacity, whereas facilities
 in Collier County discharge to surface waters about 1% of their design capacity.

 Surface waters that receive discharges vary in physical, chemical, and biological
characteristics. As a result, the uses and applications of this disposal option are very site-
 specific. The estuarine and lagoon systems that receive discharges are  typically large
expanses of mostly shallow water. Tampa Bay is the largest open estuary  in Florida,
                                      ES-19

-------
encompassing over 400 square miles, with an average depth of 12 feet (Pribble et al.,
1999). Sarasota Bay is about 56 miles long and about 300 feet to 4.5 miles wide. It has an
average depth between 8 and 10 feet (Roat and Alderson, 1990). The Indian River
Lagoon is comprised of several water bodies and stretches for about 156 miles, from
south of Daytona Beach to near Palm Beach (Adams et al., 1996). Effluent entering these
three major surface water systems must undergo advanced wastewater treatment.

These shallow surface-water bodies include many different and extensive features, such
as wetlands, lakes, streams, and canals. In South Florida, many of these surface-water
bodies have direct hydrologic connections to the underlying surficial aquifers.

Regulatory Oversight of Discharge to Surface Waters

Florida regulations require that wastewater receive at least secondary treatment and basic
disinfection before discharge. Discharge to Class I waters (potable water supply) requires
principal treatment, (defined within State requirements as secondary treatment, basic
disinfection, filtration and high level disinfection) and discharges to the Tampa Bay,
Sarasota Bay, and Indian River Lagoon systems require advanced wastewater treatment.
Additional permitting requirements may include that effluent meet certain effluent limits,
such as technology-based effluent limits or water-quality-based effluent limits.

State-mandated discharge standards apply for overall pollutants, nitrogen, total suspended
solids, and fecal coliforms. Currently, there are no Federal or State limits for protozoan
pathogens in wastewater but Florida applies its reclaimed water standard (no more than
5.8 cysts or oocysts per 100 liters for Cryptosporidium and no more than 1.4 cysts per
100 liters for Giardia} to wastewater discharged to surface waters.

Water-quality standards also apply to discharges to surface waters. The standards are
dependent on the end-use class of the receiving surface water. The following classes are
relevant to the risk assessment: Class I surface waters may be used as a potable water
supply; Class II waters may be used for shellfish propagation or harvesting; Class III
water may be used for recreation or can support the propagation and maintenance of a
healthy, well-balanced population offish and wildlife.

Option-Specific Risk Analysis for Discharge to Surface Waters

Because of the variability between and within the receiving surface waters and the
regulatory standards governing them, the human health and ecological risks associated
with this option are site-specific. To overcome this challenge, surface-water quality was
the major parameter used in the risk analysis. The water quality of discharges was
compared to the relevant surface-water quality standards. The risk analysis also examined
the types of adverse effects that might be anticipated when standards are exceeded.

The potential stressors associated with this option can vary substantially, depending upon
the level of treatment applied to the wastewater, but may include nutrients (nitrogen and
phosphorus), metals, organic compounds, pathogenic microorganisms, and hormonally
active agents. Metals remaining in discharged effluent may be taken up and
                                      ES-20

-------
bioaccumulate in the food chain to potentially toxic levels. Excess nutrients, particularly
nitrogen and phosphorus, are stressors and can have a significant effect on aquatic
ecosystems. Excess nutrients can change biological productivity and community structure
and cause harmful algal blooms.

Before discharge to surface water, wastewater must undergo secondary treatment and
basic disinfection.  Stressors in wastewater subjected to secondary treatment and
disinfection are similar to those remaining in water bound for ocean disposal, that is,
inorganic and volatile organic compounds; synthetic organic constituents; microbial and
miscellaneous constituents; and trihalomethanes, a disinfection by-product. However,
wastewater discharged to Tampa Bay or to Indian River Lagoon must be treated using
advanced wastewater treatment. This typically includes secondary treatment, basic
disinfection, nutrient removal (nitrification, denitrification, and phosphorus removal),
removal of metals and organic compounds, and filtration to remove cyst-forming
protozoans.

In many cases, it is not possible to identify the source of stressors in surface waters. In
South Florida, surface-water quality shows significant degradation that may be from
urban and agricultural activities (McPherson et al., 2000; McPherson and Halley,  1996).
Canal water in urban and agricultural areas commonly contains high concentrations of
nutrients, coliform bacteria, metals, and organic compounds when compared to water
taken from remote areas. The relative contribution of stressors from these sources
compared to the contribution from effluent discharge is poorly understood.

Contamination of Florida's coastal environments with enteric viruses, bacteria, or
protozoans is a widespread and chronic problem. Potential causes include the prevalence
and high density of septic systems, the predominantly porous and sandy soils, the  karst
topography, and the hydrologic connections between groundwater and coastal
embayments and estuaries (Lipp et al., 2001;  Paul et al., 1995). The disinfection of
treated effluent before discharge eliminates most pathogens. However, pathogenic
protozoans are resistant to disinfection and can persist in effluent.

Under optimal natural conditions, estuaries and lagoons are some of the most productive
and diverse habitats. Potential receptors are many and range from microscopic
phytoplankton and submerged aquatic vegetation to reptiles, birds, marine mammals, and
humans. Threatened and endangered species,  such as the West Indian manatee and green
and loggerhead sea turtles, can be found in these estuary and lagoon areas. Of the  almost
800 fish species known to occur in east-central Florida, more than half use the  estuaries
and lagoons during part of their life cycle (Gilmore et al, 1981; Gilmore 1995). These
shallow waters are important breeding and spawning areas for many fish.

USDWs or water-supply wells may be affected where surface waters that receive effluent
have a direct hydrological connection to the groundwater resource. In South Florida,
there is a strong interconnection of groundwater and surface water, but the processes and
hydrologic fluxes are not well understood. Canals, which frequently receive discharge,
are often hydrologically connected to groundwater. Whether the canal is being recharged
                                      ES-21

-------
or is discharging to groundwater depends on the specific hydrologic conditions, but
canals that discharge to groundwater provide a pathway for potential contamination of the
underground drinking water supply.

In addition to USDWs, human health exposure can include dermal contact with an
affected water body, incidental ingestion of affected water, ingestion of contaminated fish
or shellfish (near or removed from the point of discharge), or exposure to toxins from
harmful algal blooms. Ecological resources can include fish and other organisms present
in the surface water body at the point of discharge as well as those that are removed from
but may be affected by the discharge. Also, nutrient loading can adversely impact waters,
especially sensitive or impaired waters, and this in turn can destabilize the aquatic
system.

Human Health Risk and Ecological Risk Characterization of Discharge to Surface
Waters

Effluent discharged to surface waters poses limited risks to human health. The volumes
discharged in South Florida are not great, there is a generally higher level of effluent
treatment, and the discharges are typically intermittent. Although not required at all
treatment plants, AWT is used to remove additional nutrients, organic compounds, and
total suspended solids. Facilities using this treatment level frequently are within the
standard requirements and may be below detection levels for some effluent constituents
(for example, pathogenic microorganisms, inorganic compounds, organic compounds,
volatile organic compounds). Pathogenic protozoan levels are generally low and usually
within recommended standards. However, some facilities did not meet the recommended
levels, even when using filtration. In these cases, there is a potential human health risk,
albeit a low  risk.

Similarly, the overall risk to ecological receptors is low. This is because most facilities
use AWT. For example, based on information collected before and after Tampa Bay
implemented AWT, the relative risk of AWT-treated wastewater is lower than the risks
posed by wastewater treated to a lesser degree.

Although the risk analysis identified limited human health and ecological risks associated
with the discharge of treated effluent to surface-water bodies, the receiving surface
waters in many cases are already significantly impacted by contamination from urban and
agricultural  sources. Additional inputs of nutrients, even from effluent containing low
nutrient concentrations, are likely to pose some ecological risk. The cumulative effect of
the various inputs into these surface waters is not currently understood. Considerable
scientific study and public involvement would be needed to identify and address the
problems associated with the relative contributions of different sources of stressors to
these estuarine and lagoon waters.
                                      ES-22

-------
 OVERALL RISK ASSESSMENT

 The degree of treatment of wastewater before its disposal is an important factor that
 controls the concentrations of stressors present at the receptor. Risk can be significantly
 reduced by attenuation factors, such as travel time, distance, filtration by geologic media,
 dispersion by groundwater or ocean currents, biological degradation, and adsorption.

 Pathogenic microorganisms pose a significant  human health risk for deep-well injection
 and discharge to ocean outfalls and, to a lesser extent, aquifer recharge and discharge to
 surface waters.  Filtration can significantly reduce the level for pathogenic protozoans in
 treated water. However, natural water bodies may contain pathogenic protozoans at levels
 that exceed the  recommended levels.

 In addition, nutrient levels can still exceed ambient water-quality levels. Excess nutrients
 can lead to a variety of ecological problems and can affect entire ecosystems.

 Most risk analyses have data and knowledge gaps, and it is important to acknowledge and
 understand their extent and type. This risk assessment identified data and knowledge gaps
 for all the options (Exhibit ES-10).
Deep Well Injection
Site-specific mechanisms
of transport (for example,
porous media flow vs.
conduit flow); locations
and connectivity of
natural conduits such as
solution channels.

The fate and transport of
pathogenic
microorganisms; rates of
die-off and natural
attenuation.

The extent of, if any,
reduction hi inorganic
stressor concentration
resulting from local
geochemical conditions
(for example, rate of
biologically mediated
transformation of
ammonia).
Groundwater monitoring
data to describe transport
to (or within) the Biscayne
and surficial aquifers.
Aquifer Recharge
(using RIBs)
Site-specific hydrologic
data (for example,
horizontal hydraulic
conductivities); site-
specific estimates of
horizontal time-of-travel.

Groundwater monitoring
data to describe transport
within the Biscayne and
surficial aquifers.

Geospatial data to
describe proximity to
water-supply wells
(especially private wells).

Fate and transport of
pathogenic micro-
organisms still present
after disinfection; rates
and die-off.





Discharge to the Ocean
The potential for adverse
ecological effects near
outfalls.

The potential for
bioaccumulation (such as
metals, persistent organic
compounds) through food
chains.

Water-quality and
ecological monitoring
downcurrent of outfalls
(beyond mixing zones).

The potential for changes
in ocean currents, sea
level, or climate that
might affect changes in
circulation and
transportation patterns or
exposure.





Discharge to
Surface Waters
The potential for adverse
ecological effects near
pouits of discharge.

The potential for
bioaccumulation (such as
metals, persistent organic
compounds) through food
chains.

Water-quality and
ecological monitoring data
for specific potentially
impacted water bodies.

The nature and extent of
recharge to surficial
USDWs.









Exhibit ES-10. Data and Knowledge Gaps
                                      ES-23

-------
Findings on Risk to Human Health

Overall, the risks to human health are generally low for the four disposal options (Exhibit
ES-11). The risks are somewhat higher in all options when there is less treatment or when
exposure pathways are short. High-level disinfection, combined with filtration for
pathogenic protozoans (using an effective process), significantly reduces risk for all the
disposal options. There is an increased risk to human health when the disposal location
coincides with recreational uses, such as the ocean (outfall location), canals, streams,
bays, and lagoons, and when discharges cause harmful algal blooms. Deep-well injection
and aquifer recharge disposal options have the potential to directly impact drinking-water
supplies, thereby creating a potential risk to human health.
Deep-Well Injection
Low where proper
siting, construction, and
operation result in
physical isolation of
stressors. with no fluid
movement.

Low where there have
been impacts to deep
USDWs; however.
exposure of current
water supplies is
unlikely.

Increased risk where
short times of travel
prevail and where
exposure of current
water supplies is more
likely.
hi all cases, the risk
would be further
reduced when injected
wastewater is treated to
reclaimed water
standards.
Aquifer Recharge
(using RIBs)
Low because of high-level
disinfection, filtration, and
treatment to reclaimed-
water standards.


Increased risk where
filtration is not adequate
to meet health-based
recommendations for
Giardia or
Cryptosporidium.

Increased risk where
chlorination results in high
levels of disinfection
byproducts (that is, failure
to dechlorinate).








Discharge to the Ocean
Low because of rapid
dilution and an absence
of drinking-water
receptors. The low
occurrence (less than 4%)
of current flow towards
the coast means that
human exposure along
coastal beaches is
reduced.

Increased risk where
recreational use is near
the discharge.

Increased risk where
discharges contribute to
stimulation of harmful
algal blooms.







Discharge to
Surface Waters
Low because of high-level
disinfection and additional
treatment (e.g. AWT
standards).

Increased risk where
filtration is not provided or
is inadequate to meet health-
based recommendations for
Giardia or Cryptosporidium.

Increased risk where
surface-water discharges are
near recreational use of
water bodies.

Increased risk where
discharges contribute to
stimulation of harmful algal
blooms.






Exhibit ES-11. Estimate of Risk to Human Health Associated With Each
Wastewater Disposal Option
Findings on Risk to Ecological Health

The risk to the ecological health of surface waters is very low for the deep-well injection
and aquifer recharge options (Exhibit ES-12). Similarly, the risk to surface waters
receiving treated discharge directly is low because of the advanced level of treatment the
wastewater receives. However, irrespective of the contribution of contaminants by treated
                                      ES-24

-------
municipal wastewater, many surface waters in South Florida are considered to be in an
impaired status. When a discharge is in close proximity to an impaired water body, there
is a higher ecological health risk.
Deep-Well Injection
The risks from chemical
constituents are low but
not zero because of
possible hydrologic
connectivity. Risks
related to pathogenic
microorganisms are low
to moderate for Dade and
Brevard counties because
of lack of disinfection
and filtration. Microbial
risk is low hi Pinellas
County because of use of
disinfection and filtration.
Aquifer Recharge
(using KUts)
Low because of possibility
of hydrologic connectivity
between wetlands and
surficial aquifer.

Cumulative and long-term
effects are not known.







Discharge to the Ocean
Low because of the
concentrations of nutrients
in the discharged effluent.

No ecological monitoring
is currently conducted.
Cumulative and long-term
effects are not known.






Discharge to
Surface Waters
Low because of the
concentrations of nutrients
in the discharged effluent.











Exhibit ES-12. Estimate of Risk to Ecological Health Associated With Each
Wastewater Disposal Option
Risks are also considered low for ocean outfalls in the areas outside the mixing zones and
for marine ecosystems that may be impacted by deep-well injection.

Discharges from ocean outfalls and discharges to surface waters will have increased risk
if the discharges cause harmful algal blooms or result in bioconcentration in food webs.
Construction of new ocean outfalls may increase risk to coral reefs.
                                      ES-25

-------
REFERENCES
Adams AW, Ainsley JD, Busby DS, Day RA, Recore KA, Rice TB. 1996. The Indian
       River Lagoon comprehensive conservation and management plan. Palatka (FL):
       The Indian River Lagoon National Estuary Program.
Brickey C. 1995. The relevance of risk assessment to exposed communities.
       Environmental Health Perspectives, 103 (Supplement 1): 89-91.
Facemire CF, Gross TS, and Guillette Jr. LJ. 1995. Reproductive impairment in the
       Florida panther: Nature or nurture? Environmental Health Perspectives. 103
       (Supplement 4): 87-42.
Gilmore RG, Donahoe CJ, Cooke DW, and Herema DJ. 1981. Fishes of the Indian River
       Lagoon and adjacent waters, Florida. Technical Report No. 41. Ft. Pierce (FL):
       Harbor Branch Foundation.
Gilmore RG. 1995. Environmental and biogeographic factors influencing icthyofaunal
       diversity: Indian River Lagoon. Bulletin of Marine Science. 57(1):153-170.
Green Mountain Institute for Environmental Democracy. 1997. Comparative Risk
       Resource Guide, 3rd ed. Montepelier (VT).
Lipp EK, Farrah SA, and Rose JB. 2001. Assessment and impact of microbial fecal
       pollution and human enteric pathogens in a coastal community. Marine Pollution
       Bulletin. 42(4): 286-293.
McPherson BF and Halley R. 1996.  The South Florida Environment-A Region Under
       Stress. U.S. Geological Survey Circular 1134. Reston (VA): USGS.
McPherson BF, Miller RL, Haag KH, and Bradner A. 2000. Water Quality in Southern
       Florida, 1996-1998. U.S. Geological Survey Circular 1207. Reston (VA): USGS.
Paul JH, Rose JB, Brown J, Shinn E, Miller S, and Farrah S. 1995. Viral tracer studies
       indicate contamination of marine waters by sewage  disposal practices in Key
       Largo, Florida. Applied and Environmental Microbiology.  61:2230-2234.
Pribble RJ, Janicki AJ, and Greening H. 1999. Baywide Environmental Monitoring
       Rreport 1993-1998. Technical Report #07-99. Tampa Bay  Estuary Program.
Roat P and Anderson M. 1990. Sarasota Bay Projects State of the  Bay Report. Sarasota
       (FL): Sarasota Bay Project National Estuary Program.
Hazen and Sawyer. 1994. SEFLOE H Final Report: Broward County Office of
       Environmental Services North Regional Wastewater Treatment Plant, City of
       Hollywood Utilities Department Southern Region Wastewater Treatment Plant,
       Miami-Dade Water and Sewer Department North District  Wastewater Treatment
       Plant, Miami-Dade Water and Sewer Department Central District Wastewater
       Treatment Plant. Hollywood (FL): Hazen and Sawyer. Submitted to National
       Oceanic and Atmospheric Administration.
[U.S. EPA] U.S. Environmental Protection Program. 1998.  Guidelines for Ecological
       Risk Assessment. EPA/630/R-95/002F. Washington, DC: US EPA.
                                    ES-26

-------
[U.S. EPA] U.S. Environmental Protection Program. 2000. Science Policy Handbook:
      Risk Characterization. EPA 100-B-00-002, December 2000. Washington, DC:
      Office of Science Policy, Office of Research and Development.
[U.S. EPA] U.S. Environmental Protection Program.2001. Envirofacts Warehouse Safe
      Drinking Water Information System (SDWIS). Internet:
      hrtp ://www.epa. gov/enviro/html/sdwis/sdwis_ov.html.
                                    ES-27

-------
[ This page intentionally left blank ]

-------
 1.0    INTRODUCTION

 This report provides a relative risk assessment of four management options for treated
 municipal wastewater in South Florida. The four wastewater management options
 evaluated by the study are the following:

    •  Disposal via deep-well injection
    •  Aquifer recharge
    •  Ocean outfall disposal
    •  Disposal via surface-water discharge.

 The study described in this report compiles new and existing sources of information and
 provides an evaluation of potential human health and ecological risks associated with the
 four wastewater management options studied.

 1.1    Congressional Mandate

 This study was conducted in response to a Congressional mandate included in the fiscal
 year 2000 appropriation language:

       Within available funds, the conferees direct EPA to conduct a relative risk
       assessment of deep-well injection, ocean disposal, surface discharge, and aquifer
       recharge of treated effluent in South Florida, in close cooperation with the
       Florida Department of Environmental Protection and South Florida municipal
       water utilities.

 1.2      Purpose

 There is an immediate need for information that will assist EPA, Florida regulatory
 agencies, and concerned stakeholders to determine an appropriate course for proposed
 revisions to rules concerning Class I underground injection wells in South Florida. These
 wells inject treated wastewater below the lower most underground source of drinking
 water and the surficial aquifers that provide much of Florida's drinking water.
 Groundwater monitoring information indicates that the injected wastewater has migrated
 from the injection zone into overlying layers of the subsurface. Stakeholders have
 expressed concern that such migration may compromise drinking-water sources.

This risk assessment will provide information  that regulators, utilities, and communities
 in South Florida can use to make informed judgments and decisions regarding  wastewater
 management.

Wastewater management involves complex and interrelated issues, many of which are
beyond the scope of this risk assessment. Examples of such complex issues include
modified wastewater management approaches, changes in the required level of treatment,
encouraging flexibility in use of management options and backup methods, economic
comparisons relating risks to management costs, and consideration of water conservation
                                       1-1

-------
and water quantity. However, a risk assessment that takes all of these issues into account
would far exceed the scope and available resources for this study. Accordingly, this risk
assessment has been designed to address the Congressional mandate directly. It does not
attempt to assess the full range of risk-related considerations that figure into wastewater
management decision-making.

Because the purpose of the study is to characterize potential risks to human health and the
environment, this study does not incorporate an analysis of cost-effectiveness. As a
result, operational lifespan, implementation and maintenance costs, and other economic
issues will not be assessed. However, the potential for system failure for each of the four
wastewater management options will be addressed, with particular emphasis on the
potential for failure of deep injection wells.

The geographic area covered in this study includes areas south of a line drawn from the
northern end of Brevard County west to the northern end of Pinellas County (figure 1-1).
In an effort to focus data collection within areas exhibiting the most urgent wastewater
management needs, the heavily populated counties of Dade, Palm Beach, Broward,
Pinellas, Brevard, Sarasota, and Hillsborough were selected.

EPA acknowledges that this study area may or may not be entirely consistent with what
has been traditionally considered as South Florida. However, EPA collected data and
conducted this risk assessment within a study area that provides for the fullest and most
informative evaluation of the human health and ecological risks associated with the four
studied management options.
                                       1-2

-------
                                                                               Duval \  Jacksonville
                                                                                             Seminole
                   Areas where data were collected.
                                                                                                        Miami
Figure 1-1. The South Florida Study Area

-------
[ This page intentionally left blank ]

-------
2.0    BACKGROUND

This report analyzes risk in areas that are the most densely populated or that exhibit
hydrogeologic conditions that will affect the risks associated with different wastewater
management options. Wastewater management needs in South Florida are most critical in
southeast Florida and in the more densely populated cities along both the Atlantic and
Gulf coasts of Florida. The interior of South Florida and the Everglades have the lowest
density of wastewater treatment plants. The distribution of public municipal wastewater
treatment plants in South Florida is shown in Figure 2-1 (FDEP, 2002). Municipal
wastewater treatment plants reviewed for this study are listed in Table 2-1, according to
the county in which they are located.

The tables in Appendix 1 provide data on the water quality of treated wastewater. Other
data used in this study are also presented in Appendix 1, including data on the following
topics:

    •  Chemical constituents (Appendix Table 1-1)
    •  The Southeast Florida Outfall Experiment or SEFLOE (Appendix Table 1-2)
    •  Microorganisms in wastewater (Appendix Table 1-3)
    •  Groundwater monitoring of fecal colifornis (Appendix Tables  1-4 and 1-5)
    •  Injection well locations, capacities, and treatment (Appendix Table 1-6).

2.1    Wastewater Management Options Used in South Florida

Wastewater treatment facilities often incorporate multiple management options to
ensure continuous operation. The capacity of South Florida counties to manage treated
wastewater using different management options is illustrated in Figure 2-2. Discharge
volume capacities, not actual flow volumes, are represented in this figure. Information
for this figure was obtained from the Florida Department of Environmental Protection
(DEP) wastewater facilities database (FDEP, 2002) and the Florida DEP (personal
communication, Kathryn Muldoon, February, 2002). Note that the  DEP database does not
always distinguish between Class I deep injection wells and Class V shallow injection
wells.

Broward, Palm Beach, and Dade counties discharge the majority of their treated
wastewater through ocean outfalls and deep injection wells. In Hillsborough, Sarasota,
Pinellas, and Collier counties, aquifer recharge can be done using reclaimed water,
surface water discharge, or deep injection well disposal, depending on irrigation needs
and weather conditions. Facilities in Brevard County discharge reclaimed water to the
Indian River Lagoon only when there is no demand for irrigation water. Dade, Broward,
and Palm Beach counties primarily use Class I deep injection wells and ocean outfalls to
dispose of wastewater treated to secondary standards, but they also reuse a small amount
of reclaimed water.
                                       2-1

-------
                Legend
          Miin  c  al Waste ater real ent Plants
            scusse  n e ort
           IherMun c  al Waste ater real ent Plants
           n South  lor  a  rea
 WW P WW   Waste ater real en! Plant  ac 1 t


   WW P    .  ance Waste ater  real ent Plant
                                   HILLSBOROUG

                                      PINEL
                        [ Howard F. Curren AWTP
                             South Gate AWWTP
                                                                                                       Seacoast Utilities WWTP
                                Gulf Gate AWWTP
                                                                                                        South Central Regional WWTP ]
                                                                                                           Cfty of Boca Raton WWTP
                                                                                                          Broward County Norm Regional WWTP
                                                                                                           'Sunrise WWTP (Sawgrass) I
                                                                                                        Fort Lauderdafe-G.T.Lohmeyer WWTP]
                                                                                                         City of Hollywood WWTP
                                                                                                          Mlami-Oade North District WWTP
                                                                                                          Miami-Dade Central District WWTF
                                                                                                        Miami-Dade South District WWTF
                                                                                                       Source: litorii a ' e. 'art1 lento • En1 ' ran- 'erital Protecll on' 2001
Figure 2-1.  Municipal Wastewater Treatment Plants in South Florida

-------
 Table 2-1.    Wastewater Treatment Plants Discussed in This Report
Wastewater
Treatment Plant
Cape Canaveral
South Beaches
City of Fort
Lauderdaled
City of Sunrise
(Sawgrass)d
City of Holly woodd'e
Broward County North
Regional*1' e
Golden Gate (Naples)d
Miami-Dade South
Districtd
Miami-Dade Central
District"
Miami-Dade North
District46
Howard F. Curren
(Tampa)
Seacoastd
BocaRatond'e
South Central
Regional/Delray
Beachd-e
Albert Whitted
GulfGated
South Gate"
County
Brevard
Brevard
Broward
Broward
Broward
Broward
Collier
Dade
Dade
Dade
Hillsborough
Palm Beach
Palm Beach
Palm Beach
Pinellas
Sarasota
Sarasota
Type of Disposal
Surface water, reuse
Surface water, reuse,
deep-well injection41
Deep-well injection
Deep-well injection
Some Reuse, Ocean
outfall
Some Reuse, Ocean
outfall, deep-well
injection
Reuse
Deep-well injection
Ocean outfall, deep-
well injection
Ocean outfall, deep-
well injection
Some reuse
Surface water,
reclaimed
Reuse and Deep-
well injection
Some reuse. Ocean
outfall
Ocean outfall
Deep-well injection,
Some reusec
Surface water
Surface water, reuse
Treatment
Secondary and
High-level
disinfection
Secondary and
High-level
disinfection
Secondary
Secondary
Secondary and
High-level
disinfection
Secondary and
High-level
disinfection
Secondary and
High-level
disinfection
Secondary
Secondary
Secondary and
High-level
disinfection
Advanced
Secondary and
High-level
disinfection
Secondary and
High-level
disinfection
Secondary and
High-level
disinfection
Secondary and
High-level
disinfection
Advanced
Advanced
Design or
Current Capacity
inm£d)a'b
1.80
12.4
43
13
42
80
0.95
112.5
121
112.5
96
12
20
24
12.4
1.80
1.36
a mgd = million gallons per day
b FDEP,2001
c US EPA, 1997
d Englehardtetal.,2001
e Hazen and Sawyer, 1994
                                         2-3

-------
K>
            Q
            O
            o
            CO
            Q.
            «
            O
            D)
            '«
            O
                350
                300
                250
                200
                150
                100
                 50
                      Broward
Dade
      Pinellas
County
Sarasota
                                                              Data source: Florida DEP, 2001
                                                              Wastewater Facilities Database
                                                              http://www. dep. state, fl. us/water/
                                                              wastewater/download.htm
                                                              Note: Database describes wastewater
                                                              management options in a manner that
                                                              differs from county to county.
                                                               B  Injection Well - Well Type
                                                                   Unspecified

                                                               DQ  Deep Injection
                                                                                                                Ocean Outfall
                                                                                                                Surface Water
                                                                                                             0  Aquifer Recharge
H Aquifer Recharge and
   Surface Water

D Aquifer Recharge/Injection
   Well and Surface Water

E3 Aquifer Recharge/
   Injection Well

Q Aquifer Recharge/
   Deep Injection Well
         Figure 2-2. Wastewater Management Options and Design Capacities for Counties in South Florida

-------
 Approximately 1.2 million people are served by the Dade Central and Dade North
 District wastewater treatment plants, which discharge a total of approximately 230
 million gallons per day (mgd) to the open ocean (Marella, 1999). Both outfalls have
 multi-port diffusers. In Broward County, approximately 80 mgd are treated and
 discharged to the Atlantic Ocean (Marella, 1999). (Note:  This is 1995 data and may not
 reflect the impact of Class I injection wells that became operative in 1996; at this time,
 discharge to the ocean may have been diverted to the Class I wells.)

 Wastewater treatment facilities located in Brevard, Collier, and Pinellas counties are
 permitted to discharge to surface waters. However, these  facilities often use other
 management options, such as spray irrigation, in conjunction with discharges to surface
 water. When there is no need for spray irrigation, treated  wastewater may be discharged
 into a surface-water body or injection well. For example,  the South Beaches wastewater
 treatment facility in Brevard County discharges into the Indian River Lagoon when there
 is no demand for  irrigation water.

 In Sarasota, two wastewater treatment plants, Gulfgate and Southgate, discharge into
 freshwater canals (Phillippe Creek and Methany Creek). These eventually drain to
 Roberts Bay (Camp, Dresser, McKee, 1992; Roat and Alderson, 1990). The Sarasota
 facilities have no  alternative  for discharging wastewater and thus treat to advanced
 wastewater standards at all times.

 In Pinellas County, the City of Clearwater and the City of Bellaire have permits to
 discharge to surface waters. Bellaire discharges to Clearwater Bay, and the City of
 Clearwater Northeast Wastewater Treatment Plant discharges to Tampa Bay. These
 facilities also have the option of reusing treated or reclaimed wastewater.

 Each of the four studied methods of managing treated wastewater is described briefly
 below and in more detail in Chapters 4 through 7.

 2.1.1  Class I Deep-Well Injection

 Class I underground injection wells are used to dispose of secondary treated municipal
 wastewater to deep geologic  strata. Injection zones are selected so that they are situated
 beneath the lowermost geologic formation that contains an underground source of
 drinking water (FDEP, 1999). An underground source of drinking water (USDW) is
 defined as an aquifer, or portion of an aquifer, with a sufficient quantity of ground water
to supply a public water system and containing a total dissolved solids concentration of
 less than 10,000 milligrams per liter (mg/L) (FDEP, 1999; 40 CFR 144.3).

 Class I wells are located throughout the South Florida study area, including Dade,
Brevard, and Pinellas counties. Wastewater is injected at depths ranging from 650 to
 3,500 feet below the land surface (US EPA, 1998). Management of treated municipal
wastewater by Class I deep-injection wells constitutes approximately 20 percent (0.44
billion gallons per day) of the total wastewater disposal capacity in Florida, based on
design capacity (FDEP, 1997).
                                       2-5

-------
Movement of injected fluids into USDWs by Class I is prohibited by Federal and State
requirements. A major purpose of the Federal and State regulations is to protect the
quality of USDWs by regulating the construction and operation of injection wells to
ensure that the injected fluid remains in the injection zone. 40 CFR 146 establishes
criteria and standards that apply to the construction, operation, and monitoring of Class I
wells. Many specific regulations governing the construction and operation of injection
wells serve to prevent fluid movement into USDWs.

Chapter 4 discusses deep-well injection in greater detail and examines potential human
and ecological risks associated with this wastewater management option.

2.1.2  Aquifer Recharge

Aquifer recharge involves the infiltration of water into the ground and includes such
practices as infiltration basins, percolation ponds, wetland treatment systems, and
irrigation of turf, landscaped areas, and  crops. Ultimately, these result in recharging
groundwater aquifers and may benefit wetlands habitat as well. For these reasons, aquifer
recharge using reclaimed wastewater is  widely considered to be a beneficial reuse of
treated wastewater.

Under the State of Florida's regulatory framework (the Florida Administrative Code
[FAC]), Chapter 62-600 contains definitions of secondary treatment, disinfection levels,
and requirements for effluent disposal systems; and Chapter 62-610 contains detailed
requirements for a wide range of reuse options; and that Chapter 62-611 regulates
discharges to wetlands.

Chapter 5 discusses aquifer recharge in  greater detail and examines potential human and
ecological risks associated with this wastewater management option. Wastewater
treatment and disinfection is discussed in detail in Section 2.3.

2.1.3  Ocean Outfalls

There are six existing publicly owned treatment facilities  that use ocean outfalls for
management of treated wastewater in South Florida (Hazen and Sawyer,  1994). A
seventh ocean outfall with limited discharge capacity is located in the Florida Keys,
according to Hoch et al. (1995). The six major ocean outfalls in southeast Florida
discharge effluent from the Dade Central District, Dade North District, City of
Hollywood, Broward County, Delray Beach, and Boca Raton treatment facilities. The
outfalls discharge secondary-treated chlorinated wastewater effluent at ocean depths
ranging from 27.3 meters to 32.5 meters. Discharge points are located between 1,515 and
5,730 meters offshore.

The southeast Florida outfalls discharge along the western boundary of the Florida
Current, a tributary of the Gulf Stream.  The Florida Current is a fast-flowing current,
with maximum current speeds occurring in the Florida Strait between southeast Florida
and the Bahamas, in the vicinity of the southeast Florida outfalls. Maximum current
                                       2-6

-------
 speeds measured at the outfall sites during the Southeast Florida Outfall Experiment
 (SEFLOE) were upwards of 60 to 70 centimeters per second. The speed and strength of
 the Florida Current causes effluent plumes to be rapidly dispersed (Huang et al., 1998;
 Proni et al., 1994; Proni et al., 1996; Proni and Williams, 1997).

 Chapter 6 discusses ocean outfall disposal in greater detail and examines potential human
 and ecological risks associated with this wastewater management option.

 2.1.4  Surface-Water Discharges

 Surface-water disposal consists of discharge of treated municipal wastewater into
 estuaries, lagoons,  canals, rivers, or streams. Surface-water discharge of treated
 municipal wastewater is limited and discouraged in South Florida because of potential
 ecological and health concerns. There are no known permitted discharges into fresh water
 lakes or ponds in South Florida (personal communication, K. Muldoon, Florida DEP).
 Discharge into canals is the predominant form of surface-water discharge (Marella, 1999;
 Kapadia and Swain, 1996; Englehardt et al., 2001; personal communication, K. Muldoon,
 Florida DEP). Discharges into estuaries may also be permitted. Tampa Bay, Roberts Bay,
 and the Indian River Lagoon each receive surface-water discharges through discharges
 into canals or estuaries that empty into these coastal embayments (City of Tampa Bay
 Study Group, 2001).

 Wastewater intended for discharge to certain coastal embayments generally must be
 treated to advanced wastewater treatment standards. Advanced wastewater treatment
 refers to secondary treatment, plus further removal of nitrogen and phosphorus to attain
 the 5mg/L CBOD5, 5 mg/L TSS, 3 mg/L total nitrogen (as N) and 1  mg/L total
 phosphorus (as P) or treatment to water-quality-based effluent standards. Discharge to
 Tampa Bay and Indian River Lagoon areas must be treated to these standards. While it
 represents a reasonable assumption for the level of treatment required for surface water
 discharges, it is not a formal statewide requirement.

 Most surface-water discharges are also subject to water-quality-based effluent limits
 (WQBELs) established using the processes outlined in Chapter 62-650, F.A.C. WQBELs
 generally include nutrient limits for nitrogen and phosphorus  established to protect water
 quality in the receiving waters. This may include very stringent nutrient limits.  While
 filtration  may be needed to achieve the TSS limit, it is not specifically designed to
 remove pathogenic protozoa, nor is it required to do so. In addition, any new or expanded
 surface water discharge is subject to Florida's Antidegradation Policy.

 Chapter 7 discusses surface water discharges in greater detail and examines potential
human and ecological risks associated with this wastewater management option.

2.2   Drinking Water in South Florida

Concerns about potential effects on drinking-water quality He at the heart of stakeholder
anxieties regarding management of treated wastewater. In order to evaluate potential
                                       2-7

-------
human health risks associated with these management options, it is important to
understand the sources of drinking water used by South Florida communities.

The USGS National Water Quality Assessment Program (NAWQA) has estimated that
ground water accounts for approximately 94 percent (872 million gallons per day, or
mgd) of the water used by 5.8 million people in South Florida as of 1990, generally from
wells less than 250 feet deep in the surficial aquifer. The remaining  6 percent of drinking
water is supplied by surface water sources (McPherson et al., 2000). (Note that the
NAWQA report encompasses an area of South Florida that is approximately similar to
the area of this risk study, with the exclusion of a portion of Sarasota County and the
inclusion of several other counties not addressed in this study.)

Most Community Water Systems within the geographic area covered by this study are
supplied by ground water. As of October 18, 2001, a total of 133 Community Water
Systems in five counties (Brevard, Broward, Dade, Palm Beach, and Pinellas Counties)
provide ground water from their own wells or purchase ground water from nearby
utilities. Current figures indicate that only 12 Community Water Systems provide surface
water to their customers (US EPA, 2001).

Water suppliers that use ground water generally use either the Floridan Aquifer or the
Biscayne Aquifer as a water source. The Biscayne Aquifer underlies 4,000 square miles
in Broward, Dade, and Palm Beach Counties. The Miami-Dade Water and Sewer
Department withdraws approximately 330 mgd from the Biscayne Aquifer for
distribution to the City of Miami and surrounding communities. The City of Fort
Lauderdale draws water from the Biscayne Aquifer as well.  The City of St. Petersburg, in
Pinellas County, purchases ground water (from the Floridan Aquifer).

-------
                            East
                              A'
                     UNNAMED
                     SURHCIAL
                    AQUIFERS-AND
                    INTERMEDIATg
                     AQUIFERS,
                  UN01FFERENTIATEO
                                                           SURFICfAL AQUIFER
                                                                SYSTEM
                                                       INTERMEDiATE AQUIFER SYSTS-M
                        ATLANTIC
                        OCEAN
          BIG CYPRESS    THE    \
            SWAMP   EVEflGMGES  \
                           •"A.
   Base from U.S. Geological Survey Oigital data, 1:2,000,000,197E
   Atbers Equal-Area Conic projection
   Standard Parallels 29'30' and 45" 30'. central roeridan -83" 00'
           SO MILES    VERTICAL SCALE
•I-,	,-i-T--l.	1	1       GREATLY SXAGGERATED
      50 KILOMETERS
                                                                       Source: McPherson elal (2000)
Figure 2-3.  Hydrologic Profile of South Florida Aquifer System
2.2.1  Floridan Aquifer System

The Floridan Aquifer System underlies approximately 100,000 square miles in southern
Alabama, southeastern Georgia, southern South Carolina, and all of Florida. Several large
cities in the southeastern United States use the Floridan Aquifer as a drinking water
source, including St. Petersburg in Florida.  In addition, the aquifer is a source of water
for many smaller communities and rural areas. During 1985, approximately three billion
gallons per day of fresh water were withdrawn from the Floridan Aquifer (USGS, 2000).

In most places, the Floridan Aquifer can be divided into two aquifers (the Upper and
Lower Floridan aquifers) with a confining layer of material in between. The hydraulic
properties and geology of the Upper Floridan aquifer are better known than the properties
of the Lower Floridan because the Lower Floridan occurs at greater depths than the
Upper Floridan, and therefore fewer borehole  data are available. Most of the fresh water
that is withdrawn from the Floridan Aquifer is pumped from the Upper Floridan.
                                          2-9

-------
Since 1988, approximately 320 million gallons per day of wastes are injected into
disposal wells that empty into the Lower Floridan; about 97 percent of this volume is
municipal wastewater.

2.2.2  Biscayne Aquifer System

The Biscayne Aquifer system, the main source of water for Dade, Broward, and
southeastern Palm Beach Counties, underlies approximately 4,000 square miles (USGS,
2000). In 1985, approximately 786 million gallons per day of fresh water were withdrawn
from the aquifer for all purposes; withdrawals as of 1990 were somewhat greater. About
70 percent of the water is estimated to be withdrawn for public supply. Major population
centers that depend on the Biscayne aquifer for water supply include Boca Raton,
Pompano Beach, Fort Lauderdale, Hollywood, Hialeah, Miami, Miami Beach,  and
Homestead. Water from the Biscayne Aquifer also supplies the Florida Keys with water
transported from the mainland by pipeline.

Because the Biscayne Aquifer lies at shallow depths and is highly permeable, it is highly
susceptible to contamination. According to the USGS, this aquifer is the sole source of
drinking water for 3 million people.

The Biscayne Aquifer lies on top of the Floridan Aquifer, and is separated from that
deeper aquifer by approximately 1,000 feet of low-permeability clay deposits. The
Biscayne Aquifer ranges in thickness from a few feet in the west to about 240 feet near
the Florida coast.

2.2.3  Surficial Aquifer

In areas of South Florida outside the Biscayne Aquifer, the unnamed surficial aquifer is
used locally for community and public water supply.

2.2.4  Drinking-Water Quality in South Florida Communities

The City of St. Petersburg purchases ground water pumped by the City of Tampa from
the Floridan Aquifer. Routine monitoring reported in the city's 2000 Water Quality
Report indicates that the water system produces drinking water that meets all Federal and
State drinking water standards. According to data in the report, the concentrations of all
constituents in the water were below Federal and State Maximum Contaminant Levels
(MCLs). The maximum concentration of arsenic (MCL 50 ug/1) was 3.3 ug/1 and the
maximum concentration of nitrate (MCL for nitrate is 10 mg/1) was 0.05 mg/1 during the
latest round of water quality testing.

Dade County withdraws approximately 330 million gallons per day of fresh water for
distribution to Miami and surrounding communities. The Miami-Dade 2000 Water
Quality Report indicates that concentrations of all constituents detected in the water were
below Federal and State MCLs. The concentration of nitrate as measured at nine water
                                      2-10

-------
 treatment plants ranged from ND (not detected) to 7 mg/1; the concentration of arsenic at
 the nine plants ranged from ND to 2 ug/1.

 The Biscayne Aquifer is used by millions as a source of drinking water and is suitable for
 most other purposes. In some areas in Broward county and portions of Dade County,
 however, the water is colored as a result of decomposing organic material in the aquifer.
 While this coloration is an aesthetic issue, it does not present a risk to human health.

 Canals managed by the South Florida Water Management District have been used in
 South Florida to control flooding and drainage. These canals are hydraulically connected
 to the Biscayne Aquifer and present a potential contamination route. Major sources of
 contamination to the Biscayne Aquifer include salt water intrusion and infiltration of
 contaminants from the  canal system. Other potential sources of contamination include the
 infiltration of substances spilled on the ground, fertilizer carried in surface runoff, septic
 tanks, and improperly constructed disposal wells.

 2.3    General Description of Wastewater Treatment

 2.3.1  Wastewater Treatment Methods Used in Florida

 In the State of Florida,  there are four primary means of managing treated municipal
 wastewater:

    •  Release of treated wastewater effluent to ocean outfalls
    •  Release of treated wastewater effluent to surface waters
    •  Aquifer recharge of reclaimed wastewater
    •  Underground injection of treated wastewater into subsurface geologic formations
       using Class I injection wells.

 A precise knowledge of the regulation, treatment, and disinfection of municipal
 wastewater is important for evaluating and understanding human health and ecological
 risks associated with the four different wastewater management alternatives. Treatment
 and regulatory oversight are two critically important risk management tools that greatly
 affect the final risk determination.

 Regulations governing water-quality treatment and the quality of water in receiving water
 bodies are important because they require that wastewater be treated to a certain standard
 that depends on its management method; therefore, treated wastewater is likely to have a
 composition that falls within a predictable range. Risk assessment is made simpler when
 the quality of treated wastewater can be expected to be fairly predictable. Furthermore,
regulations concerning  water quality are based upon rational evidence that human health
 or ecological entities would be better protected if such standards were met. Risk
 assessment is made easier when such standards exist. In addition, comparison of risks of
 different management options may depend to a large extent upon the kind and amount of
treatment required. Regulations for treatment of wastewater and standards for receiving
                                       2-11

-------
waters are discussed generally in Chapter 3 and in Chapters 4 through 7 for each
wastewater management option.

In order to understand how wastewater treatment reduces risks, it is helpful to understand
the composition of untreated wastewater and to compare it with that of treated
wastewater. Typical untreated (raw) municipal wastewater contains a variety of
constituents, the concentration of which depends on the type and size of commercial and
industrial flows added and on the amount and quality of ground water infiltrating into the
sewage system. For instance, food-handling wastewater (for example, from food stores
and restaurants) can have higher concentrations of organic matter than typical domestic
wastewater, while industrial flows may exhibit higher levels of metals. Untreated
wastewater typically contains notably high concentrations of pollutants, including organic
and inorganic compounds, microorganisms and metals (WPCF, 1983; Metcalf and Eddy,
1991; Richardson and Nichols, 1985; Krishnan and Smith, 1987; and Williams, 1982).
Table 2-2 lists typical concentrations and ranges of several raw wastewater constituents
as well as the percent removal of these constituents that can be achieved using primary
and secondary wastewater treatment methods.
                                      2-12

-------
Table 2-2.     Typical Levels of Constituents in Wastewater and Percent Removal Using Treatment (Primary and
               Secondary)
Raw Wastewater (mg/L)
Constituent
BOD5
COD
TSS
VSS
NH4-N
NO3 + NO2-N
Org-N
TKN
Total N
Inorg P
OrgP
Total P
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Manganese
Mercury
Nickel
Silver
Zinc
Typical
220
500
220
165
25
0
15
40
40
5
3
8
0.007
0.008
0.2
0.1
0.9
0.1
0.14
0.001
0.2
0.022
1.0
Range
110-400
250-1000
100-350
80-275
12-50
0
8-35
20-85
20-85
4-15
2-5
6-20
0.002-0.02
O.005-0.02
O.05-3.6
O.02-0.4
0.10-1.9
O.02-0.2
0-0.3
O.OOO 1-0.0045
0.004-0.044
—
Percent Removal
Primary
0-45
0-40
0-65
—
0-20
0-20
0-20
5-10
—
0-30
34
38
44
49
43
52
20
11
55
36
Secondary
65-95
60-85
60-90
—
8-15
15-50
20-60
10-20
—
10-20
28
33-54
58-74
28-76
47-72
44-69
13-33
13-83
33
79
47-50
Secondary Effluent (mg/L)
Typical
20
75
30
—
10
6
4
14
20
4
2
6
0.002
0.01
0.09
0.05
0.36
0.05
0.05
0.001
0.02
0.002
0.15
Range
10-45
35-75
15-60
—
<1-20
<1-20
2-6
10-20
10-30
2-8
0-4
4-8
—
O.005-6.4
O.05-6.8
O.02-5.9
0.10-4.3
O.02-6.0
O.OOO 1-0. 125
O.02-5.4
—
O.02-20
Note: Partially adapted from WPCF, 1983; Metcalf and Eddy, 1991; Richardson and Nichols, 1985; Krishnan and Smith, 1987; and Williams. 1982.
[Please insert note explaining meaning of cells occupied by em dash (—): for example,"— = no data was collected for this consitutent."

-------
Raw wastewater must be treated at a wastewater treatment facility prior to discharge,
regardless of the disposal method. Wastewater treatment facilities provide what is known
as primary, secondary, and/or tertiary or advanced treatment. The dividing boundaries
between these levels of treatment can become blurred, especially in recent years with the
development of new processes that can accomplish several treatment objectives at once.
As Table 2-2 indicates, percent removal of raw wastewater constituents depends largely
on the level of treatment, though it is important to note that even primary treatment alone
will produce a much cleaner effluent. Treatment facilities are designed to meet national,
state and local treatment standards, and the processes are chosen on the basis of those
standards and local wastewater composition. Most importantly, the level of treatment is
dictated by the disposal or reuse option chosen.

Wastewater treatment and disinfection methods and levels are summarized below. A
summary of treatment methods used in South Florida is presented in Table 2-4.
Disinfection methods are summarized in Table 2-5. Treatment and disinfection for
different wastewater management options are discussed fully in Chapters 4 through 7.

2.3.2  Definitions of Wastewater Treatment Methods and Levels of Disinfection

Primary wastewater treatment generally consists of physical separation of solids from
the wastewater and includes screening and grinding operations, as well as sedimentation.

Secondary wastewater treatment provides for the removal of suspended solids and
biodegradable organic matter using chemical and biological processes before discharge to
receiving waters. Secondary treatment, which often includes basic disinfection (described
below), is required for ocean discharge but disinfection is not required for underground
injection via Class I injection wells. Pursuant to the Clean Water Act, EPA first issued its
definition of secondary treatment in 1973. Current Federal standards for secondary
treatment are included in 40 CFR Part 133 and presented in Table 2-3. The State's
requirements for secondary  treatment are contained in Chapter 62-600, F.A.C.
Table 2-3. National Standards for Secondary Treatment
Parameter Minimum % Removal Maximum 7-Day Avg. Maximum 30-Day Avg.
BOD5, mg/L
TSS, mg/L
pH, units
85 45
85 45
Within range of 6.0 to 9.0 at all times
30
30
Most secondary treatment of domestic wastewater is accomplished using activated sludge
processes. These processes utilize microorganisms already present in the wastewater. The
wastewater is aerated and mixed vigorously, which increases contact between the
microorganisms and both organics and oxygen. The microorganisms oxidize the
dissolved and suspended organics into carbon dioxide and water. Inorganic and organic
nitrogen, sulfur, and phosphorus are oxidized to nitrates, sulfates, and phosphates. Some
suspended organic and mineral solids are not broken down; these are settled out in
                                       2-14

-------
 clarifiers or a clarification step. The liquid flows out of the top of the clarifier, and after
 undergoing whatever final treatment is required, it is on its way out of the wastewater
 treatment facility.

 Principal treatment and disinfection (more advanced secondary) requires secondary
 treatment and high-level disinfection. The reclaimed water must meet a standard of 5.0
 mg/L of total suspended solids before application of the disinfectant and total nitrogen is
 limited to 10 mg/L. Filtration is also required for total suspended solids control,
 increasing the ability of the disinfection process to remove protozoan pathogens.

 Reclaimed water treatment requires secondary treatment, filtration, and high-level
 disinfection. The quality of water discharged via reclaimed water treatment systems is
 intended to be high so that it may be reused. Reclaimed water treatment is required if
 wastewater is being reclaimed for reuse.  A standard of 5.0 mg/1 TSS (a single sample
 maximum applied after the filter  and before the application of the disinfectant) is required
 for reuse projects permitted under Part III of Chapter 62-610, F.A.C. Part III imposes a
 number of additional operational and reliability requirements.

Advanced (or tertiary) wastewater treatment is a term of art that simply means
 wastewater treatment beyond secondary treatment such as processes that are used if there
 are requirements to remove specific  components, such as nitrogen and phosphorus, which
 are not removed by the secondary treatment.

 Basic disinfection  must result in  not more than 200 fecal coliforms per 100 ml of
 reclaimed water of effluent sample. Where chlorine is used, facilities must provide for
 rapid and uniform mixing and a total chlorine residual of at least 0.5 milligram per liter
 shall be maintained after at least  15 minutes contact time at the peak hourly flow. Higher
 residuals or  longer contact times  may be needed. (See Rule 62-600.440(4) F.A.C.)

High-level disinfection includes  additional removal of total suspended solids (TSS)
 beyond secondary treatment, to achieve a TSS concentration of 5.0  mg/L or less before
the application of disinfectant, in order to maximize disinfection effectiveness. It results
 in reclaimed water in which fecal coliform values (per 100 ml of sample) are  below
 detectable limits (at least 75% of all  observations: with no single sample above 25/100
mL. Where chlorine is used, facilities must provide for rapid and uniform mixing and a
total chlorine residual of at least 1.0  milligram per liter must be maintained at all times.
Larger residuals or longer contact times may be required and as well as minimum contact
times if chlorine is used as the disinfectant. This requirement does not preclude an
additional application of disinfectant prior to filtration for the purpose of improving filter
performance. (See Rule 62-600.440(5) F.A.C.)
                                       2-15

-------
REFERENCES

Camp, Dresser, McKee, Inc. 1992. Point-/Nonpoint Source Pollution Loading
      Assessment. Phase I. Final Report, Sarasota (FL): Sarasota Bay National Estuary
      Program.

City of Tampa Bay Study Group. 2001. Results of the City of Tampa Surface Water
      Compliance Monitoring Program for the Year 2000 and Examination of Long-
      Term Water Quality and Biological Indicator Trends in Hillsborough Bay.
      Submitted to the Florida Department of Environmental Protection Southwest
      District.

Englehardt JD, Amy VP, Bloettscher F, Chin DA, Fleming LE, Gokgoz S, Rose JB,
      Solo-Gabriele H, and Tchobanoglons G. 2001. Comparative Assessment Of
      Human And Ecological Impacts Form Municipal Wastewater Disposal Methods
      In Southeast Florida. University of Miami.  Submitted to the Florida Water
      Environmental Association Utility Council.

[FDEP] Florida Department of Environmental Protection. 2002. Wastewater Treatment
      Facilities Reports. Internet: http://www.dep.state.fl.us/water/wastewater/
      download.htm.

Hazen and Sawyer. 1994. SEFLOEII Final Report: Broward County Office of
      Environmental Services North Regional Waste-water Treatment Plant, City of
      Hollywood Utilities Department Southern Region Wastewater Treatment Plant,
      Miami-Dade Water and Sewer Department North District Wastewater Treatment
      Plant, Miami-Dade Water and Sewer Department Central District Wastewater
      Treatment Plant. Hollywood (FL): Hazen and Sawyer. Submitted to National
      Oceanic and Atmospheric Administration.

Hoch MP, Cifuentes LA, and Coffin R. 1995. Assessing Geochemical and Biological
      Fate for Point Source Loads of Sewage-Derived Nitrogen and Organic Carbon in
      Coastal Waters of Southern Florida. Washington (DC): US EPA.

Huang H, Fergen RE, Tsai JJ, and Proni JR. 1998. Evaluation of mixing zone models:
      CORMIX, PLUMES, and OMZA with field data from two Florida ocean outfalls.
      Environmental Hydraulics, pp.249-254,

Kapadia A and Swain ED. 1996. South Florida Ecosystem Program: Quantifying
      Freshwater Discharge for Coastal Hydraulic Control Structures in Eastern Dade
      County, Florida. FS-123-96.  Washington (DC): US EPA.

MarellaRL. 1999. Water withdra\vals, use, discharge, and trends in Florida, 1995.
      USGS Water Resources Investigations Report 99-4002. Talahassee (FL): USGS
      prepared in Cooperation with the Florida Department of Environmental
      Protection.
                                     2-16

-------
McPherson BF and Halley R. 1996. The South Florida Environment—A Region Under
       Stress. U.S. Geological Survey Circular 1134. Washington (DC): USGS.

McPherson BF, Miller RL, Haag KH, and Bradner A. 2000. Water Quality in Southern
       Florida, 1996-1998. U.S. Geological Survey Circular 1207. Washington (DC):
       USGS.

Proni JR, Dammann WP, Craynock JF, Stamates SJ, Commons D, Fergen R, Huang H,
       Ferry R, Goldenberg B, Mandrup-Poulson J, Monson J, and Williams R. 1996.
       Worst case effluent discharge conditions and adaptive processing of effluents for
       southeast Florida outfalls. Abstract, in Proceedings, 68th Annual Conference,
       WEFTEC '95. Miami Beach, Florida. October 21-25. Alexandria (VA): Water
       Environment Federation.

Proni JR, Huang H, and Dammann WP.  1994. Initial dilution of Southeast Florida ocean
       outfalls. Abstract in: Journal of Hydraulic Engineering. 120:1409-1425.

Proni JR and Williams RG. 1997. Acoustic measurements of currents and effluent plume
       dilutions in the western edge of the Florida Current. Abstract in: Acoustic Remote
       Sensing Applications. Singal SP (ed.). New Delhi, India: Narosa Publishing
       House.

Roat P and Alderson M. 1990. Sarasota  Bay Project: State of the Bay Report. Sarasota
       (FL): Sarasota Bay National Estuary Program.

[US EPA] United States Environmental Protection Agency.  1997. National Biennial
       RCRA Hazardous Waste Report:  Based on 1995 Data. Washington (DC): US
       EPA.

	. 2001. Envirofacts Warehouse Safe Drinking Water Information System.
       Internet: http://www.epa.gov/enviro/html/sdwis/sdwis_ov.html

[USGS] United States Geological Survey. 2000. HA 730-G Floridan Aquifer System. In:
       Ground Water Atlas of the United States. Washington (DC): USGS.

York DW, Menendez P, and Walker-Coleman L. 2002. Pathogens in reclaimed water:
       The Florida experience. 2002 Water Sources Conference.
                                     2-17

-------
[ This page intentionally left blank ]

-------
3.0    METHODOLOGY FOR RELATIVE RISK ASSESSMENT

Risk assessment is a process that evaluates the likelihood that adverse ecological or
human health effects will occur as a result of exposure to stressors (US EPA, 1998a). It is
a process for organizing and analyzing data, information, assumptions, and uncertainties.
Risk assessment involves identification of hazards or stressors, analysis of the linkage
between exposure to stressors and effects on receptors, and risk characterization (US
EPA, 1998a). Risk assessments are used to help risk managers determine priorities for
actions that are designed to manage or reduce risk. Risk management is a decision-
making process which involves such considerations as risk assessment, technological
feasibility, statutory requirements, public concerns, and other factors.

In this study, the terms risk analysis, risk characterization and relative risk assessment
refer to the processes of analyzing risks, describing risks, and the final comparison of
relative risk assessment, respectively.

For this study, risk analysis and relative risk assessment of four different wastewater
management options involved three steps:

    1.  Creation of a generic risk analysis framework (GRAF) for each wastewater
       management option
   2.  Conducting a risk analysis of each management option using the GRAF  and
       characterizing the risk associated with each option
   3.  Comparing the risks associated with all four wastewater management options,
       based on the results of risk analysis of each management option, to arrive at a
      relative risk assessment.

3.1    Generic Risk Analysis Framework and Problem Formulation

In order to provide a consistent and comprehensive procedure for analyzing risk, a
generic risk analysis framework (GRAF) was developed. The GRAF is a procedure for
describing all potential risks and identifying all possible hazards, sources, exposure
pathways, and  effects on receptors, based on a generalized approach to the issue. This
framework, also known as problem formulation, outlines potential issues to be analyzed
for risk, using site-specific information. In this study, the GRAF was used to develop a
conceptual model of potential risk for each management option. The GRAF incorporates
human health and ecological risk components.

The use of a GRAF to  analyze risks of individual wastewater management options is
based upon the Guide for Developing Conceptual Models for Ecological Risk
Assessments (Suter, 1996), a risk assessment framework outlined in EPA's Residual Risk
Report to Congress (US EPA, 1999a), and EPA's ecological risk assessment framework,
presented in Guidelines for Ecological Risk Assessment (US EPA, 1998a).

The first step in developing a GRAF is formulating the problem and developing a
conceptual model of potential risk. In formulating the problem, the purpose for
                                       3-1

-------
conducting the risk assessment is articulated, data are collected and assessed, and
potential stressors, receptors, and exposure pathways are selected for further analysis.
This information is then organized within a conceptual model, which is a "written
description and visual representation of predicted relationships between ecological [or
other] entities and the stressors to which they may be exposed" (US EPA, 1998a). For
each wastewater management option, a conceptual model helps to define the information
necessary to complete the risk analysis. The analyses necessary to characterize risk are
then conducted as part of the next  step, the option-specific risk analysis and
characterization (see below).

Potential stressors include constituents of concern, such as compounds and elements,
present in treated wastewater and their degradation byproducts or other derivatives.
Potential secondary stressors include other effects of stressors that may pose additional
risks themselves. Secondary stressors and the risks they pose can be particularly difficult
to anticipate and describe.

Receptors are the human and ecological entities that are exposed to stressors and that may
suffer potential adverse effects. Exposure to a stressor must be demonstrated before the
linkage between a stressor and an adverse effect can be evaluated. Exposure pathways are
the ways in which stressors and receptors are brought into contact with each other.
Assessment endpoints provide yardsticks for measuring the effects of stressors. Important
assessment endpoints selected for this study included drinking-water  quality standards,
surface- and marine-water quality  standards, and other human health  and environmental
indicators. Where no assessment endpoints existed, potential adverse effects were
evaluated using a weight-of-evidence approach.

3.2    Option-Specific Risk Analysis and Risk Characterization

The second step in risk assessment is conducting an analysis and evaluation of the
conceptual model of risk for each wastewater management option. In this step, specific
information concerning stressors, receptors, and exposure pathways is used to analyze
relationships  and anticipate potential adverse effects (or risks). In this study, such
information included site-specific data on hydrogeology, water quality, wastewater
treatment plant effluent, and wastewater management options used in South Florida. In
order to evaluate exposure pathways, information concerning properties of stressors (for
example, concentration,  solubility, half-life, tendency to bioaccumulate) and the
environment they pass through (groundwater, surface water, ocean, subsurface geology,
and soils) were compiled and analyzed. Information about large-scale physicochemical
processes that determine exposure pathways is also essential for determining whether
receptors will actually be exposed to stressors. Such information was  used to evaluate and
refine the conceptual model for each wastewater management option.

Evaluation of the conceptual model involves an exposure analysis and risk
characterization. Exposure analysis is critical to risk analysis and risk assessment;
without exposure to a stressor, there is no risk (US EPA, 1998a). In this study, as the
conceptual models were evaluated and refined,  pathways that did not  result in exposure
                                       3-2

-------
 of a receptor to stressors or exposure pathways that were insignificant or improbable
 were eliminated. Areas of uncertainty and data gaps were identified. Whenever
 appropriate, conservative assumptions were made that may result in overstating, rather
 than understating, exposure and risk. A conservative approach will be more protective of
 human and ecological health.

 Risk characterization involves describing the potential adverse ecological and human
 health effects (risks) that may result from exposure to stressors (US EPA, 2000). Risks
 may be estimated, compared, or qualitatively described. In this study, risk
 characterization was performed at assessment endpoints for each conceptual model of a
 wastewater management option. Upon completion of the risk characterization, issues that
 pose actual risks were identified, while issues that pose little or no risk were eliminated or
 assigned lower priority in the final conceptual model of risk. Other risk factors were also
 taken into account, such as receptor sensitivity, response to change, and potential for
 recovery if the stress is removed or decreased (Brickey, 1995; GMIED, 1997).

 3.3    Relative Risk Assessment

 Risks and risk factors may be compared using a variety of methods; comparisons may be
 quantitative, semiquantitative, or qualitative. Frequently, such an assessment requires that
 professional judgment be applied to evaluate the relative magnitude of effects (US EPA,
 1998a;Suter, 1999a, 1999b).

 In this study, relative risk assessment relied upon results of the option-specific risk
 analysis and risk characterization to compare the risks and risk factors of the four
 wastewater management options. This relative risk assessment used a qualitative
 approach to prioritizing risk factors and describing the relative risks and risk factors.
 There are many risk factors that could have been used in the relative risk assessment.
 Risk factors were chosen on the basis of how they contributed to making useful
 comparisons between the potential risks to human and ecological health. Chapter 8
 compares risk findings for each wastewater management option and discusses their
 priorities.

 The following sections provide detailed descriptions of the risk methodology used.

 3.4    Detailed Description of Problem Formulation

This study of relative risk develops conceptual models of risk that are based on the
physical, chemical, and biological processes that govern the fate and transport of
 discharged wastewater constituents. Developing an understanding of such large-scale fate
 and transport processes is critical for providing  the risk manager with the necessary
information to make informed decisions on managing and decreasing  risks. Without an
understanding of the physical, chemical, biological, and human factors that influence
risk, a risk manager may expend time and resources on managing risk symptoms without
addressing and eliminating the causes of risk.
                                       3-3

-------
3.4.1   Selection of Potential Exposure Pathways

Once treated wastewater is released into the environment, the processes that determine
fate and transport of wastewater constituents (stressors) define the large-scale nature of
exposure pathways that must be evaluated. These large-scale processes act upon stressors
in ways that are strongly governed by the specific chemical and physical properties of the
stressors themselves. How these large-scale processes operate in the environments that
receive discharges of treated wastewater  also varies. Descriptions of the receiving
environments (for example, groundwater, surface water, subsurface geology, and soils)
are given in Chapters 4 through 7, which examine each of the wastewater management
options in detail.

Advection, dispersion, and dilution are large-scale physical processes that play an
important role in determining the transport of wastewater constituents. Advection
involves mixing and transport by bulk movement of water and is often the single most
important mechanism responsible for migration of wastewater constituents. Dispersion
refers to slow spreading of constituents in response to gradients in concentration
(molecular diffusion) and other phenomena. Dilution is a reduction in concentration of a
stressor or other wastewater constituent, which may result from advection or dispersion.

In groundwater, the large-scale movement of wastewater constituents in the subsurface is
strongly influenced by the characteristics of the geological media through which
discharged effluent and groundwater flows. Porous media flow occurs where primary
porosity exists, and it can result in widely varying rates of groundwater flow, depending
on the  size of pores, amount of pore space, and interconnection of pore spaces. Secondary
porosity refers to larger fractures or solution channels in sediments or rock, where
groundwater and effluent can move along solution channels, fractures, and other
preferential flow paths. In such preferential flow, advective transport rates may be  greater
than porous media flow rates. In this case, dispersion frequently results from mixing at
intersections of fractures and as a result of variations in fracture openings.

The eventual fate of wastewater constituents in the environment determines the final
concentrations of stressors to which receptors may be exposed. Attenuation describes a
variety of processes involving interactions between wastewater constituents and the
environment that cause concentrations of constituents to decrease as time passes.
Examples of processes that may result in attenuation include filtration, precipitation,
settling, biological  uptake, chemical transformation, dissolution and adsorption of
constituents. Porous media may allow filtration of small bacteria and viruses, which can
result in attenuation of these microorganisms, although very small microorganisms may
be transported over long distances in porous media. Such attenuation may not occur if
open fractures and solution channels are present, which may allow more rapid transport
of both chemical compounds and microorganisms (US EPA, 1989).

Other important physical and chemical properties that influence the behavior of
wastewater constituents include the stressor's solubility in water; tendency to adsorb to
soil, sediments or geologic media; and half-life. Wastewater constituents with higher
                                       3-4

-------
solubilities may remain longer in effluent and groundwater and may also be present at
higher concentrations in the initial effluent. The tendency to adsorb or bind to soil,
sediments, or geologic media is determined by complex interactions between wastewater
constituents and the physical and chemical environment. Adsorption of a constituent can
result in retardation, or slowing, of the transport of stressors. For organic components,
organic carbon partition coefficients (koc) provide measures of this tendency. Chapters 4
and 5 use such characteristics, in conjunction with distribution coefficients (ka) and other
measures, to determine rates of retardation for wastewater constituents.

The residence time of a compound or element in the environment is equivalent to the
lifetime of the compound or element before attenuation or other processes cause it to
dilute or disappear. The half-life (ti/2) of a compound or element is the time required for it
to decrease to  half of its  initial concentration. Half-life values take into account
biodegradation and hydrolysis. Biodegradation is a geological process whereby
microorganisms bring about chemical changes that can reduce the concentration of a
specific wastewater constituent. Hydrolysis is a chemical reaction that adds water to the
chemical structure of a compound, disrupting existing bonds or adding new bonds.
Hydrolysis can increase solubility of a compound in water and enhance biodegradation,
but it may also make a constituent more biologically available (Suthersan, 2001).

3.4.2  Definition of Potential Receptors

For this risk assessment, several potential receptors were selected. Drinking-water
receptors are groundwater or surface-water resources that are potential receptors of
underground or surface-water contaminants derived from treated wastewater. Potential
drinking water receptors include underground sources of drinking water (USDWs),
shallow public-water supply wells, private drinking-water wells, and some surface-water
bodies used for drinking water sources (the latter are very uncommon in South Florida).
Potential ecological receptors in surface water and ocean environments include organisms
and ecosystems. Potential human receptors are people who may be exposed to treated
wastewater constituents through recreational or occupational activities that bring them
into contact with the disposed water.

3.4.3  Selection of Assessment Endpoints

The assessment endpoints chosen for this study are related to the type of receptor chosen.
The first category of assessment endpoints pertains to USDWs and public and private
drinking-water supply wells.  For these drinking-water receptors, drinking-water standards
were used as assessment endpoints. Federal drinking-water standards, also known as
maximum contaminant levels, or MCLs, were designed to protect human health by
establishing minimum standards for drinking water. MCLs are assumed to be protective
of human health, although they may not be relevant to ecological standards. The Florida
Department of Environmental Health (DEP) also regulates water quality of Class I
surface waters intended for drinking water sources. In addition to treatment and
disinfection requirements for the different wastewater management options, DEP
                                       3-5

-------
regulations ensure protection of groundwater quality by establishing minimum criteria for
groundwater according to Florida Administrative Code (FAC) 62-520.400.

Construction, operation, and monitoring of wastewater treatment facilities to certain
standards are also considered in this category of drinking water-related assessment
endpoints. All management methods are also subject to regulations concerning operation,
maintenance, and monitoring.

The second category of assessment endpoints is used for ecological risk assessment in
fresh surface-water bodies and the ocean.  Surface-water quality standards for fresh water
and marine water are intended to protect human recreation and ecological values. DEP
regulations protect surface-water quality through an extensive set of regulations
contained in FAC 62-302. These include state surface-water quality standards for fresh
water and nearly marine or marine waters (Class III standards),

The third category of assessment endpoints addresses unregulated substances that may be
present in drinking-water supplies, treated municipal wastewater effluent, and other water
bodies. For unregulated substances,  a weight-of-evidence approach was used, based on
examination of the scientific literature concerning the effects of these substances.
Examples of unregulated substances include emerging contaminants, such as hormonally
active substances (endocrine-disrupting compounds), surfactants, and a wide range of
other organic and inorganic compounds. Emerging contaminants are of concern because
there is some evidence, based on a limited number of studies, that they may cause
adverse effects in humans or other organisms. However, extensive and definitive testing
under controlled conditions has generally  not been conducted. Where possible, a range of
concentrations that may have adverse effects is defined, and the concentration in USDWs
or other water bodies is compared with this range-of-effects levels.

Assessment endpoints and the regulatory standards for surface water, groundwater,
drinking  water, and other operational standards are described more fully in Chapters 4
through 7 for each wastewater management option.

3.4.4  Selection of Potential Stressors

General characteristics of the potential human health or ecological stressors selected for
this study are described in this section. Understanding the behavior and characteristics of
stressors  and their response to wastewater treatment is critically important in the analysis
of risk. The stressors considered for this risk assessment were selected based on their
occurrence in treated wastewater, scientific information concerning their toxic properties
or other potential adverse effects, whether they are representative of a larger group of
similar compounds, and their long-term fate in the environment.

In order to conduct a focused risk assessment, suitable representatives of each major
category  of stressors were chosen. Criteria for selection of representative  stressors that
might affect human health included  severity of effects, level and efficacy  of wastewater
treatment, representative behavior, and whether the representative stressor provides a
                                        3-6

-------
conservative (that is, protective) approach to evaluating risk. Contaminants of concern to
public health also included substances for which human health effects are not yet fully
understood, but for which there may be adverse human health effects, based on
laboratory tests, observed effects, or other evidence.

General categories of human health stressors selected for this study include the
following:

    •   Pathogenic microorganisms (for example, viruses, bacteria, protozoans)
    •   Inorganic compounds and elements (for example, metals and inorganic nutrients)
    •   Synthetic organic compounds (for example, pesticides and surfactants)
    •   Volatile organic compounds (VOCs)
    •   Hormonally active agents (for example, endocrine modulators and disrupters).

Representative ecological stressors that may cause adverse effects on organisms or
ecosystems were selected based on a review of the scientific literature. Ecological
stressors were chosen if they are known or suspected stressors to aquatic ecosystems,
cause toxic effects in aquatic species, and are commonly found in wastewater effluent.
Because many similar physical, chemical, and biological processes occur in both fresh-
water and marine systems, the contaminants of concern are similar in both environments.
Categories of ecological stressors selected for this study include the following:

    •   Inorganic compounds and elements (for example, inorganic nutrients and metals)
    •   Synthetic organic compounds (for example, pesticides, surfactants)
    •   Volatile organic compounds (VOCs)
    •   Hormonally active agents (for example, endocrine modulators and disruptors)
    •   Pathogenic microorganisms.

The general categories of human  health and ecological stressors and the representative
stressors selected to represent different stressor categories are listed in Table 3-1.
                                       3-7

-------
Table 3-1.    Representative Human Health and Ecological Stressors Selected for
              this Study
Stressor Category
Pathogenic microorganisms
Inorganic compounds (metals,
metalloids)
Inorganic nutrients
Volatile organic compounds
(VOCs)
Synthetic organic compounds
(SOCs)
Hormonally active agents
(endocrine-disrupting compounds)
Representative Human
Health Stressors
Rotavirus, total
coliform, fecal coliform,
enterococci,
Cryptosporidium
parvum, Escherichia
coll, Giardia lamblia
Arsenic, copper
Nitrate, ammonia
Tetrachloroethene
(PCE)
Chloroform
(trihalomethanes) and
chlordane (pesticides)
Di(2-ethylhexl)phthalate
(DEPH)
Representative
Ecological Stressors
Cryptosporidium
parvum
Arsenic, copper, lead,
silver, cyanide
Nitrate, total nitrogen,
ammonia, total
phosphorus,
orthophosphate
Tetrachloroethene
(PCE)
Methylene blue anionic
surfactant (MBAS)
Estrogen equivalence
The characteristics of the selected Stressors are described below.

3.4.4.1 Pathogenic Microorganisms

Microbial pathogens in water pose a high-priority public health concern (Raucher, 1996).
In the United States, the number of microbiological diseases originating in contaminated
drinking water is estimated to be as high as 40 to 50 million cases per year. While the
total number of outbreaks of diseases caused by contaminated drinking water has
decreased by 20% since the mid-nineties, the proportion of outbreaks associated with
groundwater sources has increased by almost 30% (PSR, 2000). The emergence of new
pathogens (for example, Escherichia coli O157:H7 and Cryptosporidium parvum},
antibiotic-resistant strains of microorganisms, and a larger sensitive population have
resulted in increased public health concerns (Rose et al., 2001). Microbiological diseases
caused by ingestion of contaminated shellfish are included in this category of waterborne
infections because contaminated water is often the major carrier (Wittman and Flick,
1995). Enteric microbial pathogens (that is, microbes that live in the intestinal tracts of
humans and animals and that cause disease) present in wastewater are listed in Table 3-2.
                                       3-8

-------
 Table 3-2.    Microbial Pathogens Potentially Present in Untreated Domestic
              Wastewater
Bacteria
       Campylobacterjejuni
       Escherichia coli
       Legionella pneumophila
       Salmonella typhi
       Shigella
       Vibrio cholerae
Helminths
       Ancylostoma duodenale (hookworm)
       Ascaris lumbricoides (roundworm)
       Echinococcus granulosis (tapeworm)
       Enterobius vermicularis (pinworm)
       Necator americanus (roundworm)
       Schistosoma
       Strongyloides stercoralis (threadworm)
       Taenia (tapeworm)
       Trichuris trichiura (whipworm)	
Protozoa
       Cryptosporidium parvum
       Giardia lamblia
       Balantidium coli
       Entamoeba histolytica
Viruses
       Adenovirus (51 types)
       Astrovirus (5 types)
       Calicivirus (2 types)
       Coronavirus
       Enteroviruses (72 types)
       Hepatitis A
       Norwalk agent
       Parvovirus (3 types)
       Reovirus (3 types)
       Rotavirus (4 types)
Source: York etal., 2002.
Depending upon the level of treatment and disinfection, concentrations of microbial
pathogens in treated wastewater discharged to the environment can vary widely. An
aggressive treatment combines disinfection with filtration to kill or physically remove
microbial pathogens present in drinking water. For example, most bacteria and viruses in
wastewater are generally effectively inactivated by disinfection with chlorine and
filtration (York et al, 2002). However, disinfection byproducts, such as trihalomethanes,
that are formed when chlorine reacts with organic compounds can pose human health
concerns as well.

Survival of pathogenic microorganisms in soil and water generally is limited to days,
weeks, or months, depending on the microorganism and whether it can form cysts or
spores that persist in the environment. Survival is affected by factors such as temperature,
availability of water and oxygen, and whether an animal host is needed for survival or
growth of the microorganism. There is a small but growing body of information
concerning survival of pathogenic microorganisms in the shallow subsurface and other
microbial processes in geologic formations such as microbial denitrification in the
shallow subsurface in northeast Florida (USGS, 2000). If viruses are not inactivated by
treatment and are released, their small size and longevity may allow them to be
distributed widely through the environment. Viruses may survive in surface water and
groundwater, although most viruses typically cannot reproduce outside the human host
(PSR, 2000). Viral contamination of wells, especially private wells with no treatment,
poses concerns.
                                       3-9

-------
Potential human exposure pathways to pathogenic microorganisms include the following:

    •   Ingestion of water contaminated by exposure to wastewater
    •   Ingestion of contaminated food (such as shellfish, fish, produce, or foods
       processed in contaminated water)
    •   Dermal contact with contaminated water or soil through swimming, showers,
       spray irrigation, or occupational exposure
    •   Inhalation of contaminated water or soil (aerosols, shower spray, spray irrigation,
       dust, occupational exposure).

Secondary spread may also be possible, which includes person-to-person contact, use of
public swimming facilities, and transmission from food handlers and care facilities
(Chick etal., 2001).

Microbial growth in groundwater is not well characterized in general because of the
difficulty of obtaining microbiologically representative samples without introducing
surface contaminants. There are many gaps in knowledge concerning potential human
health effects from ingestion of pathogenic microorganisms in water:

    •   Whether indicator organisms for microbial pathogens, such as coliform, are
       representative of pathogenic microorganisms
    •   Whether environmental sources other than wastewater exist for pathogenic
       microorganisms
    •   Exposure factors
    •   Modes of transmission
    •   Modes of environmental transport of microorganisms
    •   Survival potential of microorganisms in groundwater.

Three representative pathogenic microorganisms were selected to evaluate human
exposure to treated wastewater: rotavirus, Cryptosporidium parvum, and pathogenic
strains ofEscherichia coli (E. coli). These are described below.

Rotaviruses

Rotaviruses  are highly infective viruses that can be transmitted in water, causing a highly
contagious disease that induces vomiting and diarrhea. In the United States, rotavirus has
been estimated to cause 3 million cases of childhood diarrhea, resulting in 500,000 doctor
visits, 100,000 hospitalizations, and up to 100 deaths annually (EHP, 1998a; SAIC,
2000). Because of the easily transmitted and highly contagious nature of the illness,
rotaviruses were selected as a representative of pathogenic enteric viruses.

Other enteric viruses that are associated with poor-quality or untreated wastewater have
been detected in near-shore waters and canals, including coxsackie viruses, Hepatitis A
viruses, and  Norwalk-like virus (Rose et al., 2000). These viruses, if ingested, can cause
diarrhea, aseptic meningitis, and myocarditis. Their small size (in the nanometer range)
and structure enhances viral survival and transport in water; these viruses can survive in
                                       3-10

-------
 groundwater for more than 2 months (Rose et al., 2000). Plankton and marine sediments
 may serve as reservoirs for pathogenic microorganisms, which can emerge to become
 infective when conditions are favorable (Henrickson et al., 2001).

 Cryptosyoridium varvum

 Cryptosporidium parvum, an enteric protozoan, is considered to be a major risk to U.S.
 water supplies because it is highly infectious, forms cysts and oocysts that are resistant to
 chlorine disinfection, and is difficult to filter because of its small size. Cryptosporidium
 poses significant challenges to public health and water authorities (Gostin et al., 2000). If
 it is present in drinking water, it poses  a high risk of waterborne disease (particularly for
 immunocompromised individuals). There have been 12 documented waterborne
 outbreaks of Cryptosporidium in North America since 1985; in two of these (Milwaukee
 and Las Vegas), mortality rates among exposed immunocompromised individuals ranged
 from 52% to 68% (Rose, 1997). Similar enteric protozoans include Giardia lamblia,
 Entamoeba histofytica, and Balantidium coli (York et al., 2002).

 Protozoan cysts and oocysts are very persistent in the environment, particularly where
 water exists. Dormant oocysts may remain viable for months in sewage or groundwater
 until they find a new host. Cryptosporidium infects both humans and animals and can be
 transmitted through ingestion of contaminated water or food. Secondary infection can
 also occur. Cryptosporidium forms a reproductive oocyst that, once ingested, continues
 its life cycle in the gastrointestinal tract, causing the disease Cryptosporidiosis. The
 parasite can also be spread through the fecal-oral route by infected food handlers or  in
 day-care settings. As few as 10 to 25 oocysts can cause infection; however, the disease is
 usually self-limiting with 2 to 10 days of symptoms in healthy persons. In sensitive
 populations and individuals, the disease can be life threatening.

 Chlorine, the traditional water disinfectant for killing water-borne pathogenic bacteria
 and viruses, is not as effective against Cryptosporidium as other waterborne organisms,
 for example, Giardia (Joyce, 1996). Standard screening methods have proven ineffective
 as well. Filtration is the accepted method of removing Cryptosporidium.

Because of the severity of the disease, its widespread occurrence in nature, and because
water and wastewater treatment does not always address Cryptosporidium., it was  chosen
 for use as a representative pathogenic protozoan for evaluating human health risks from
pathogenic protozoans in discharged treated wastewater.

Fecal Coliforms (Escherichia coli}

Fecal coliforms are bacteria that are normally found in human and animal wastes.
Escherichia coli, or E. coli, is a type of fecal coliform bacteria. The presence of E. coli in
water is a frequently used indicator of recent sewage or animal waste contamination,
although it is not a reliable indicator of human sewage. It is important to note that
sewage-indicator bacteria such as fecal coliforms have short survival times in the
environment and may not be good indicators of the presence of protozoans and viruses in
                                       3-11

-------
some environments (Henrickson et al., 2001). For example, one injection well monitoring
study performed in Florida found that indicator bacteria and coliphages were not
detected, while Cryptosporidium oocysts were detected at very low concentrations (Rose
etal.,2001).

Most strains of £ coli are harmless and live in the intestines of healthy humans and
animals without causing illness. However, E. coli O157:H7 is one strain of E. coli that
produces a powerful toxin that can cause severe gastrointestinal illness. Infection by E.
coli O157:H7 may cause hemolytic uremic syndrome, in which red blood cells are
destroyed and kidney failure occurs. About 2% to 7% of infections lead to this
complication. In the United States, most cases of hemolytic uremic syndrome are caused
by E. coli O157:H7 (US EPA, 2001a). Exposure may occur through ingestion,
recreational contact, or consumption of contaminated water or food (Schmidt, 1999).
Sensitive human receptors include children, the ill, the immunocompromised, and the
elderly. Because of the severity of illness that may occur upon exposure to E, coli
O157:H7, fecal coliforms were selected as a representative human health stressor.

Pathogen fate, transport, and survival in the environment are discussed more in Chapter
4. Data on concentrations of pathogenic and indicator microorganisms in treated
wastewater and from groundwater monitoring are provided in Appendix 1 (Appendix
Tables 1-3,1-4, and 1-5).

3.4.4.2 Inorganic Stressors

Wastewater contains a large number and variety of inorganic constituents, including
metals, salts, nutrients, and other substances. Many, if not all, of these inorganic
constituents are natural in origin (that is, they are  ultimately derived from natural
materials and are not "manmade" in the sense of being synthesized by humans), but their
concentrations in wastewater may be elevated because of human activities. Many
inorganic substances, if present at high enough concentrations, can pose some risk to
human health.  For this reason, many drinking-water standards (maximum contaminant
levels,  or MCLs) address the maximum amount of a given inorganic substance allowed in
drinking water. Removal of these constituents will depend upon the level and type of
wastewater treatment that is used.

Metals

Like nutrients, metals are naturally occurring and play a necessary biological role  in the
environment. However, in excessive amounts, metals can be toxic to wildlife, fish, and
aquatic organisms. Metals have complex and dynamic physical and chemical reactions in
the environment and can occur in different chemical forms or species. Metal speciation is
important in understanding biological uptake by fish and wildlife. Factors that affect
chemical speciation of metals include pH, alkalinity, the presence of organic matter and
colloidal particles, and the oxidation-reduction potential of the environment  (Stumm and
Morgan, 1981). Organisms also differ in their capacity to store, remove, and detoxify
metal contaminants (Wallace and Braasch, 1997).
                                      3-12

-------
 Copper is an example of an essential micronutrient metal that is required by plants,
 animals, and most microorganisms in trace amounts. However, at higher concentrations,
 copper is toxic to algae, inhibiting growth and photosynthesis; copper sulfate and other
 copper-containing compounds have been used to control algal blooms in fresh water
 bodies and reservoirs since the early 1900s. The bioavailability of copper, or its ability to
 be taken up by organisms, depends in large part on its speciation. Total copper is not a
 good measure of bioavailablity. Reduced copper, or Cu +, is more readily taken up by
 organisms than the oxidized form and is therefore a better indicator of potential stress.
Arsenic is a metalloid element that is often present in groundwater where underlying
rocks and soil contain arsenic salts or arsenic-containing minerals. A variety of industrial
and agricultural activities also generate or release arsenic-containing compounds,
including production and use of wood preservatives (for example, copper chromium
arsenate), mining of arsenic-containing ores, and manufacture and use of arsenic-
containing pesticides (for example, lead arsenate). Since arsenic is highly soluble,
particularly under reducing conditions (which are often found in groundwater), it may
also be highly mobile. Movement of surface water and groundwater provide important
potential transport pathways for arsenic and other metals.

Chronic arsenic exposure causes a variety of human health effects, including
carcinogenic and noncarcinogenic effects (Chowdhury et al., 2000; Morales et al., 2000).
The population cancer risks from arsenic in U.S. water supplies may be comparable to
those from environmental tobacco smoke and radon in homes (Smith et al., 1992).
Noncarcinogenic effects of low levels of arsenic include adverse effects on the
gastrointestinal system, central nervous system, cardiovascular system, liver, kidney, and
blood (Abernathy et al., 1999; Tseng et al., 2000; Kaltreider et al., 2001; and Hopenhayn-
Rich et al., 2000). At higher oral doses (600 milligrams per kilogram per day or more),
poisoning and death will result.

Human exposure to inorganic arsenic results primarily from ingestion of contaminated
drinking water or ingestion of contaminated food. Examples of food that can contain
elevated arsenic levels include fish, shellfish, crustaceans, and some cereals, such as rice,
taken from water or soils with high arsenic concentrations. Consumption offish and
shellfish from waters that contain elevated amounts of arsenic may be an important
source of arsenic in humans. In food, the highest levels of arsenic in the U.S. Food and
Drug Administration's total diet survey were found in fish, with a mean level of about 15
parts per million (ppm) As2C>3 in the edible portion of finfish (Jelinek and Corneliussen,
1977).

Approximately  5% of large and small regulated water-supply systems in the United
States are estimated to have arsenic concentrations that exceed 20 micrograms per liter
(ug/L) (Morales et al., 2000). The MCL for arsenic was formerly 50 parts per billion
(ppb). In January 2001, the EPA lowered the MCL to 10 ppb. This lower standard was
reviewed in 2001  and early 2002. After considerable public comment and deliberation,
the 10 ppb MCL level was determined to be appropriate, and the Final Arsenic Rule went
                                       3-13

-------
into effect in February 2002. The World Health Organization also recognizes an arsenic
standard for drinking water of 10 ppb.

In the marine environment, arsenic typically occurs in seawater at concentrations ranging
from 1 to 8 ppb and in sediments at 2 to 20 ppm. The distribution of arsenic in terrestrial
environments is not nearly so homogeneous, as indicated by the higher levels of arsenic
in marine organisms than terrestrial organisms; the biological concentration factor may
vary by orders of magnitude between aquatic and terrestrial organisms (Fishbein, 1981).
Arsenic may bioaccumulate in aquatic organisms. However, there is considerable
variability in aquatic food-web bioaccumulation (Penrose et al., 1977; Vallette-Silver et
al, 1999; Woolson, 1977). Organisms containing high levels of arsenic tend to be those
that ingest sediment particles while feeding; that is, benthic filter-feeders or detritus-
feeders exhibit higher concentrations of arsenic than pelagic fish.

As with copper, factors that govern biological effects of arsenic include its
bioavailability, the quantity ingested or respired, the degree of assimilation, and the
extent of retention in tissues.

Gaps in knowledge concerning arsenic and human health and ecological effects concern
detailed transport mechanisms, mobility in the environment, carcinogenesis, whether
there are cumulative or synergistic effects in combination with other contaminants,
differences in bioaccumulation by different species, and the proper dose-response
relationship to use in ecological risk assessment.

Inorganic Nutrients

Wastewater is a source of nutrients such as nitrogen, phosphorus, and other substances
that act as nutrients. Secondary treatment removes only a portion of the nitrogen and
phosphorus that may be present (see Chapter 2).

Nitrogen is the most important nutrient to consider in an ecological risk assessment for a
marine environment because nitrogen limits primary production in marine environments.
While many studies focus on total nitrogen (all forms of nitrogen), nitrate is the form that
is most readily available for uptake by algae and plants. Excess nitrate in drinking water
can potentially affect the health of infants, young children,  and pregnant women and can
cause methemoglobinemia (Knobeloch et al., 2000; Gupta et al., 2000). Human exposure
to excess nitrate can occur through drinking or accidentally ingesting water that has
elevated concentrations of nitrate. Little is known about the potential health effects of
long-term exposure to excess nitrate in drinking water. Some studies of chronic nitrate
ingestion have suggested connections to reproductive and developmental health effects,
certain cancers, childhood diabetes, and thyroid disease.

The Safe Drinking Water Act established an MCL for nitrate of 10 milligrams  per liter
(mg/L), or 10 parts per million (ppm). This federal standard is used to ensure the safety of
public water supplies, but does not apply to private wells. An estimated 2 million private
                                       3-14

-------
household water supplies in the United States today may fail to meet this federal standard
for nitrate (Knobeloch et al., 2000).

Excessive nitrate in the marine environment can stimulate phytoplankton and macroalgal
growth. This can create adverse effects such as eutrophication (reduction of available
oxygen), loss of eelgrass, dead zones because of low dissolved oxygen concentration
from decomposing organic matter, and increases in harmful algal blooms (Nixon, 1998;
Joyce, 2000). It is important to note that the 10 ppm drinking water standard for nitrate is
generally much higher than the concentration of nitrate typically present in seawater or
coastal waters, which ranges from several tenths of a part per million to several parts per
million.

Excess nutrients may create secondary stressors, such as harmful or nuisance algal
blooms. The algal toxins that may be produced by harmful algal blooms (HABs) can
cause adverse effects on humans, aquatic mammals, fish, shellfish, and other organisms.
Human ingestion of seafood contaminated by HABs can result in respiratory illness,
gastroenteritis, and skin irritation. Paralytic shellfish poisoning is one example of an
illness caused by toxin-producing dinoflageHates that form red tides. However, most
scientists agree that, although excess nutrients may be a factor in some blooms, other
environmental factors such as changes in temperature or circulation may cause many
algal blooms (Tibbetts, 2000).

Phosphorus is a nutrient of concern in freshwater ecosystems because it is frequently the
limiting nutrient for algal and plant growth, in contrast to nitrogen which tends to be the
limiting nutrient in marine waters. Excess phosphate in freshwater can cause excessive
algal growth, eutrophication, and low dissolved oxygen, just as excess nitrate in coastal
waters can result in  similar effects. Excess phosphate already exists in many of South
Florida's fresh water aquatic ecosystems, and a phosphate-based water quality standard is
being considered for Lake Okeechobee, which is heavily affected by fertilizer runoff
from adjacent agricultural  lands.

Different forms of phosphorus exist in  the aquatic environment; the most important are
orthophosphate, total phosphorus, and particulate phosphorus. Orthophosphate (also
known as soluble reactive phosphorus) is the major inorganic form of dissolved
phosphorus most readily available for biological assimilation. Total phosphorus, as the
name implies, refers to all the phosphorus in a volume of water including dissolved and
particulate forms. Orthophosphate was chosen as a representative nutrient stressor in
fresh water ecosystems.

3.4.4.3 Organic Compounds

Pesticides

Pesticides in wastewater primarily originate from stormwater runoff from lawns and
gardens and other areas where pesticides are used. Human exposure to pesticides can
occur through ingestion of contaminated drinking water, food, or dermal contact with
                                       3-15

-------
contaminated water (Moody and Chu, 1995). Potential human receptors include adults,
children, subsistence fishermen, farmers, and sensitive portions of the population, such as
the elderly and ill. A number of pesticides, including chlordane, were evaluated for deep-
well injection, while chlordane alone was used as a representative pesticide in other
wastewater management options.

Chlordane is a chlorinated insecticide that was widely used in agricultural, industrial, and
domestic applications; about  one-third of the chlordane used in  the United States was
applied to control pests in homes, gardens, lawns, and turf (ATSDR, 1995). The EPA in
1983 banned all use of chlordane, except for control of termites. In 1988, because of
concerns about carcinogenicity, toxicity, and harmful effects on wildlife, the EPA banned
its use except for fire-ant control in power transformers. Chlordane is no longer
distributed in the United States.

Despite having been banned years ago, chlordane is extremely persistent in the
environment and may remain in soil for 20 years (ATSDR, 1995a). It is associated with
many human health effects: chlordane may be carcinogenic, toxic, and impair human
immune and neurological systems (IARC, 1997; Hardell et al.,  1998; Kilburn and
Thornton, 1995). Gaps in knowledge concerning human health risks posed by chlordane
include the effects of long-term, low-dose exposure, whether it  is carcinogenic, and
whether it affects fertility, development, or neural systems.

Chlordane binds strongly to particles, does not dissolve easily in water, and may
concentrate in the surface microlayer of surface water or in aquatic sediments. Because it
is highly lipophilic, chlordane bioaccumulates in aquatic organisms. For compounds  such
as chlordane, groundwater transport is minimal (Thomann, 1995). The solids on which
the chemical is adsorbed are stationary for the most part in groundwater. In surface water,
the solids are transported during advection, and there may be significant interactions  with
aquatic sediments (Thomann, 1995).

Volatile Organic Compounds

Tetrachloroethene (PCE) is a VOC that may be formed in small quantities during
chlorination of water or wastewater. Due to its volatility, tetrachloroethene does not
remain long in surface or marine waters and will evaporate to the atmosphere; therefore,
it has little potential for accumulating in aquatic organisms (US EPA-OW, 2002).
However, in groundwater, tetrachloroethene is very mobile and persistent, which enables
it to travel significant distances. Research studies have concluded that PCE-contaminated
drinking water can  be linked to elevated incidence rates of leukemia, bladder, lung and
colorectal cancers in humans and experimental animals.

Human exposure pathways for VOCs could include drinking water, ingestion of water
during recreational or occupational activities, and exposure to vapor in water. Potential
human receptors include private well owners, who may be operating wells that are neither
monitored nor treated to national drinking water standards.
                                      3-16

-------
 The Florida Class III Marine water quality standards for tetrachloroethene are <8.85 ug/L
 on an annual average. The estimated half-lives of trichloroethylene (3.2 u^g/L) from an
 experimental marine mesocosm during the spring (8 to!6°C), summer (20 to 22°C), and
 winter (3 to 7°C) were 28, 13, and 15 days respectively (Wakeham, et al, 1983, in
 Montgomery, 2000). Toxicity tests indicate toxic levels range from 22 mg/L (LCso (24
 hours) for Daphnia magna (LeBlanc, 1980, in Montgomery, 2000) to 3,760 milligrams
 per kilogram (mg/kg) acute oral LDso in rats (TECS, 1985, in Montgomery, 2000).

 Surfactants

 Gaps in knowledge concerning the human health effects of surfactant compounds in
 drinking water include the effects of chronic low-dose exposures, suitable critical
 endpoints for risk estimates to represent sensitive populations, and the exact biological
 mechanisms by which these compounds affect human health.

 Surfactants were chosen as a potential ecological stressor to evaluate because of their
 widespread use, occurrence in wastewater, their effects upon organic matter, and the
 relative lack of information concerning their ecological effects, in comparison to
 compounds currently regulated under the Safe Drinking Water Act. Surfactants are found
 in laundry detergents and in wastewater and are known to persist in wastewater, sewage
 sludge, and the environment (Dental et al., 1993). Surfactants have also been suggested
 as a potential precursor to an endocrine-disrupting agent or estrogenic substance.
 Estrogenic substances, such as alkylphenol-polyethoxylates (APE), and other
 alkylphenols, such as nonylphenol, in sewage effluent may also originate from
 biodegradation of surfactants and detergents during wastewater treatment (Purdom et al.,
 1994 and Jobling and  Sumpter, 1993, both in US EPA,  1997). The representative
 surfactant chosen for this study is methylene blue anionic surfactant (MBAS), which is an
 anionic surfactant found in commercially available detergents (Dental et al., 1993).

 Hormonallv Active Agents

 Estrogenic hormones and potential endocrine disrupters include pharmaceuticals (for
 example, estrogens and their degradation products), surfactants, some pesticides, dioxins,
 and plasticizers. Scientific opinion is mixed concerning whether such compounds disrupt
 normal endocrine function, reproductive and developmental processes, or immunological
processes (Birnbaum,  1994; Colborn, 1995; vom Saal,  1995). Not all scientists agree that
 exposure to hormonally-active agents represents cause  for alarm. Authors of one paper
 reported that "there is  little direct evidence to indicate that exposures to ambient levels of
 estrogenic xenobiotics are affecting reproductive health" (Daston et al., 1997). In
addition, they state that "estrogenicity is an important mechanism of reproductive and
 developmental toxicity; however, there is little evidence at this point that low level
exposures constitute a human or ecologic risk." The picture regarding hormonally active
 agents  is therefore complex.

Hormonally active agents found in wastewater and in surface water elsewhere include
estradiols (an active component of oral contraceptives), as well as alkylphenols
                                      3-17

-------
(biodegradation products of nonionic surfactants). Industrial and pharmaceutical
compounds with hormonally active effects include butylbenzylphthalate (BBP), di-n-
butylphthalate (DBF), tributylphosphate, butylated hydroxyanisole (BHA),
dimethylphthalate, and 4-nonylphenol, dioxin (2,3,7,8-TCDD), bisphenol A, PCBs,
PBBs, pentachlorophenol, penta- to nonylphenols, phthalates, and styrenes (Daughton
and Ternes, 1999; Jobling et al., 1995).

Scientific studies suggest that these chemicals may cause adverse effects in aquatic
organisms and that wastewater is one source of such chemicals (Rodgers-Gray et al.,
2000; Nichols et al., 1998). Studies in Florida have documented potential endocrine
exposure effects on the Florida panther (Facemire et al., 1995) and American alligator
(Semenza, 1997). However, the sources of endocrine disrupters were not documented in
these studies.

These substances have been identified in concentrations in the nanograms-per-liter (or
parts-per-trillion) range in secondary-treated municipal wastewater effluent and receiving
waters (Huang and Sedlak, 2000; and Harries et al., 1998). Because these substances are
often highly soluble in water, they may be difficult to remove using conventional
technology; estrogenicity has been identified primarily in the water-soluble fraction of
wastewater (Raloff, 2000). Municipal wastewater treatment may remove these
compounds if they are associated with other organic particles or substances that are
removed by treatment.

Environmental monitoring indicates that such chemicals can be present in drinking water
as well (Potera, 2000). Potential human exposure pathways include ingestion of water
containing such substances, dermal contact  with water, and inhalation of volatile
compounds from water vapor. Potential human receptors include people consuming or
drinking water containing such substances and those exposed to such water as a result of
recreational or occupational activities, including subsistence fishermen and farmers.

Significant gaps in knowledge exist concerning the human health and ecological effects
of these compounds because they have only recently been recognized as potential
contaminants of concern. Comprehensive and long-term epidemiological studies are
needed to critically evaluate the effects of exposures to these compounds. Other gaps in
knowledge include the concentrations  of hormonally active substances in treated
municipal wastewater effluent, whether they present an ecological concern, effects of
exposures to mixtures, and cumulative effects of all sources of such compounds. Better
monitoring methods need to be developed in order to conduct such studies.

The EPA requires testing of commercial chemicals to determine their endocrine
disruption potential. Screening techniques to test chemicals for endocrine disruption are
being developed. Because of the relative newness of the science, no regulatory guidelines
have yet been established for concentrations of hormonally active agents in wastewater.

The hormonally active substance selected to evaluate potential human health risk was
di(2-ethylhexyl)phthalate, or DEPH. DEPH is a plasticizer, used to make polymers (such
                                      3-18

-------
 as PVC) flexible. The threshold limit value for constant 8-hour exposure in air (OSHA,
 ACGIH) is 5 ppm. DEPH poses some human health concerns, but because it is mostly
 insoluble in water and is biodegradable in small quantities, it is not considered a critical
 ecological risk stressor. Large quantities can cause liver damage and reproductive
 problems in lab animals, but the effects are reversible if the stressor is removed.

 One advanced wastewater treatment plant in South Florida also provided data on estrogen
 equivalence in treated wastewater. Estrogen equivalence is a measure of the response of
 breast cancer cells to exposure to strongly estrogenic substances, such as hormone
 replacement and birth control pills (Frederic Bloettscher, Consulting Professional
 Engineer. September 13, 2001. E-mail communication to Jo Ann Muramoto, Horsley &
 Witten, Inc.).

 3.5    Analysis Plan

 This relative risk assessment focused on characterizing and evaluating the major fate and
 transport processes that determine where the vast majority of discharged effluent and
 effluent constituents will end up. The focus is on the major exposure pathways that could
 lead to potential  exposure of receptors to effluent constituents that act as stressors.

 One of the goals of the risk assessment team was to determine whether final dilutions of
 wastewater stressors could be predicted or modeled for the ends of major exposure
 pathways (that is, at the USDW, surface water, or ocean receptors). There are many other
 potential sources of these stressors in the South Florida environment; wherever possible,
 evidence linking the stressor to the wastewater management option was sought. Analysis
 of fate and transport pathways is particularly important for singling out the concentration
 of stressors that can be ascribed to discharged treated wastewater. Without an analysis of
 fate and transport, it would be difficult to rule out other sources of the same stressor in
 surface-water receptors or the ocean or even in drinking-water receptors, such as the
 USDW or surficial aquifer.

 In order to evaluate human health risks, concentrations of representative stressors in
 treated wastewater at the treatment plant and in drinking water or other receptors were
 compared with the assessment endpoints: drinking-water standards such as the federal
 drinking-water standards (MCLs) or Florida's water quality standards for Class I waters
 intended to protect drinking-water sources. If there was no human exposure pathway
 involving a particular water resource, then the  standards for that pathway were not used
 (for example, as there is no human exposure pathway involving ingestion of seawater,
then the drinking-water standards were not used). To evaluate ecological risks,
 monitoring data for treated wastewater were likewise compared with water quality
 standards intended to protect ecological values. Examples include Florida's regulations
pertaining to Class III coastal and marine waters.

For unregulated compounds, a weight-of-evidence approach based on general scientific
 literature was used to determine whether disposal of treated wastewater  containing such
compounds could pose a risk to human health or aquatic ecosystems.
                                       3-19

-------
3.6    Final Conceptual Model of Probable Risk

When the conceptual model of potential risk was evaluated using site-specific
information, stressors, receptors, or exposure pathways that were insignificant or
improbable were eliminated. Criteria for elimination of exposure pathways, stressors, or
receptors included the following:

   •   The transport or exposure pathways that would expose a receptor to a stressor
       never or hardly ever exist or occur
   •   The time it would take for a stressor to be transported from the discharge point to
       the receptor is longer than the residence time of the stressor in the environment
   •   Wastewater treatment or other attenuation processes routinely decrease the
       concentration of a particular stressor well below required standards or assessment
       endpoints
   •   Attenuation processes that would in all probability result in a significant decrease
       in concentration of a stressor are known to exist in the receiving environment
   •   A receptor does not exist in the receiving environment
   •   There is little or no evidence that adverse effects occur from exposure of receptors
       to stressors, despite the fact that exposure must occur, using site-specific
       information.

The risk to human health or the environment from stressors in treated effluent was
described to be nonexistent to very low, when either of the following occurs—

   •   A stressor, receptor, or exposure pathway is eliminated
   •   It is demonstrated that adverse effects do not occur.

The risk was judged to be low or moderate when any of the following occurs—

   •   There is a  small chance of exposure
   •   Assessment endpoints (standards) are usually but not always met
   •   Adverse effects are possible.

The risk was judged to be moderate to high when any of the following occurred—

   •   There is a  moderate-to-high chance of exposure
   •   Assessment endpoints were almost always exceeded for some stressor
   •   Adverse effects can occur.

The risk was judged to be very high when there is a high chance of exposure and
monitoring indicates that adverse effects have already occurred.

The final conceptual model for each option describes in narrative form the risk findings
and conclusions for each wastewater management option.
                                       3-20

-------
3.7    Relative Risk Assessment

The risk findings for each wastewater management option were compared and evaluated.
Ecological and human health risk factors were compared across all four wastewater
management options. A final set of criteria for risk prioritization was developed. The
product of the relative risk comparison of wastewater management options is a prioritized
list of risk factors for each wastewater management option.
                                      3-21

-------
REFERENCES

Abernathy C, Liu Y, Longfellow D, Aposhian H, Beck B, Fowler B, Goyer R, Menzer R,
       Rossman T, Thompson C, and Waalkes M.. 1999. Arsenic: Health Effects,
       Mechanisms of Actions, and Research Issues. Environmental Health
       Perspectives, 107(7):593-587.

[ATSDR] Agency for Toxic Substances and Disease Registry. 1995(a). ToxFAQs™for
       Chlordane CAS# 57-74-9. http://www.atsdr.cdc.gov/tfacts31.html. Accessed on
       29 July 2001.

	. 1995(b). ToxFAQs™for Antimony CAS# 7440-36-0.
       http://www.atsdr.cdc.gov/tfacts23.html Accessed on 1 August 2001.

Birnbaum LS. August 1994. Endocrine Effects of Prenatal Exposure to PCBs, Dioxins,
     and Other Xenobiotics: Implications for Policy and Future Research. Environmental
     Health Perspectives. 102(8):676-679.

Brickey C. 1995. The relevance of risk assessment to exposed communities.
     Environmental Health Perspectives. 103(1):89-91.

Chick SE, Koopman JS, Soorapanth S, and Brown ME. 2001. Infection Transmission
       System Models for Microbial Risk Assessment. The Science of the Total
       Environment. 274:197-207.

Chowdhury U, Biswas B, Chowdhury T, Samanta G, Mandal B, Basu G, Chanda C,
       Lodh D,  Saha K, Mukherjer S, Roy S, Kabir S, Quamruzzaman Q, and
       Chakraborti D. 2000. Groundwater arsenic contamination in Bangladesh and
       West Bengal, India. Environmental Health Perspectives. 108(5):393-397.

Colborn T. 1995. Environmental Estrogens: Health Implications for Humans and
       Wildlife. Environmental Health Perspectives. 103(7): 135-136.

Daston GP, Gooch JW, Breslin WJ, Shuey DL, Nikiforov AI, Fico TA, and Gorsuch JW.
       1997. Environmental Estrogens and Reproductive Health: A Discussion of the
       Human and Environmental Data. Reproductive Toxicology. 11(4):465-481.

Daughton CG and Ternes TA. 1999. Pharmaceuticals and Personal Care Products in the
       Environment: Agents of Subtle Change? Environmental Health Perspectives.
       107(6):907-938.

Dental SK, Allen HE, Srinivasarao C,  and Divincnezo J. 1993. Effects of Surfactants on
       Sludge Dewatering and Pollutant Fate. Third Year Completion Report Project
       Number 06. University of Delaware: Water Resources Center.
                                     3-22

-------
 [EHP] Environmental Health Perspectives. 1998(a). Forum: Getting Rid of Rotavirus.
       Environmental Health Perspectives. 106(3): 128.

	. 1998(b). Innovations: Removing Arsenic from Drinking Water.
       Environmental Health Perspectives. 106(11):548.

	. 1998(c). The State of the Science on Endocrine Disrupters. Environmental
       Health Perspectives. \ 06(7):319.

[EXTOXNET] Extension Toxicology Network. 1996. Feticide Information Profiles.
       Internet: http://ace.orst.edu/info/extoxnet/pips/pips.html

Facemire CF, Gross TS, and Guillette Jr., LJ. 1995. Reproductive Impairment in the
       Florida Panther: Nature or Nurture? Environmental Health Perspectives.
       103(Suppl4):79.

Fishbein L. 1981. Sources, Transport and Alterations of Metal Compounds: An
       Overview. 1. Arsenic, Beryllium, Cadmium, Chromium, and Nickel.
       Environmental Health Perspectives. 40:43-64.

Gostin LO, Lazzarini Z, Neslund VS, Osterholm MT. 2000. Water Quality Laws and
       Waterborne Diseases: Cryptosporidium and Other Emerging Pathogens. American
       Journal of Public Health. 90(6).

[GMIED] Green Mountain Institute for Environmental Democracy. 1997. Comparative
     Risk Resource Guide. 3rd ed. Montpelier (VT): GMIED.

Gupta SK, Gupta RC, Gupta AB, Seth AK, Bassin JK,  and Gupta A. 2000. Recurrent
       Acute  Respiratory Tract Infections in Areas with High Nitrate Concentrations in
       Drinking Water. Environmental Health Perspectives. 108(4):363-366.

Hardell L, Lindstrom G, Van Bavel B, Fredrikson M, and Liljegren G.  1998. Some
       Aspects of the Etiology of Non-Hodgkin's Lymphoma.  Environmental Health
       Perspectives. 106(Suppl 2):679-681.

Harries JE, Jobling  S, Sumpter JP, and Tyler CR. 1998. Estrogenic Potency of Effluent
       From Two Sewage Treatment Works in the United Kingdom. Environmental
       Toxicology and Chemistry. 18(5):932-937.

Henrickson SE, Wong T, Allen P, Ford T,  and Epstein PR. 2001. Marine Swimming-
       Related Illness: Implications for Monitoring and Environmental Policy.
       Environmental Health Perspectives. 109(7):645-650.

Hopenhayn-Rich C, Browning S, Hertz-Picciotto I, Ferreccio C, Peralta C, and Gibb H.
       2000. Chronic Arsenic Exposure and Risk of Infant Mortality in Two Areas of
       Chile.  Environmental Health Perspectives. 108(7):667-673.
                                     3-23

-------
Huang CH and Sedlak DL. 2000. Analysis of Estrogenic Hormones in Municipal
       Wastewater Effluent and Surface Water Using Enzyme- Linked Immunosorbent
       Assay and Gas Chromatography/Tandem Mass Spectrometry. Environmental
       Toxicology and Chemistry. 20(1): 133-139.

[IARC] International Agency for Research on Cancer. 1997. Chlordane and Heptachlor.
       Summary of Data Reported and Evaluation. Internet: http://193.51.164.ll/htdocs/
       Monographs/Vol53/03-Chlordane-Heptachlor.HTM

	. 1998. Arsenic and Arsenic Compounds, Group 1. Internet:
       http://193.5.164.1 l/htdocs/Monographs/Suppl7/Arsenic.html

Jelinek C. and Corneliussen P. 1977. Levels of arsenic in the United States food supply,
       Environmental Health Perspectives. 19:83-87.

Jobling S, Reynolds T, White T, Parker MG, and Sumpter JP. 1995. A Variety of
       Environmentally Persistent Chemicals, Including Some Phthalate Plasticizers, Are
       Weakly Estrogenic. Environmental Health Perspectives. 103(6):582-587.

Joyce S. 1996. Capturing Crypotsporidium. Environmental Health Perspectives.
       104(8):834

	. 2000. The Dead Zones: Oxygen Starved Coastal Waters. Environmental
       Health Perspectives. 108(3): 120.

Kaltreider RC, Davis AM, Lariviere JP, and Hamilton JW. 2001. Arsenic Alters the
       Function of the Glucocorticoid Receptor as a Transcription Factor. Environmental
       Health Perspectives. 109(3):245-251.

Kilburn KH and Thornton JC. 1995. Protracted Neurotoxicity from Chlordane Sprayed to
       Kill Termites. Environmental Health Perspectives. 103(7-8):690-694.

Knobeloch L, Salna B, Hogan A, Postle J, and Anderson H. 2000. Blue Babies and
       Nitrate-Contaminated Well Water. Environmental Health Perspectives.
       108(7):675-678.

Montgomery JH. 2000. Groundwater Chemicals Desk Reference. 3rd ed. Boca Raton
       (FL): CRC Press LLC.

Moody RP and Chu I. 1995. Dermal Exposure to Environmental Contaminants in the
       Great Lakes. Environmental Health Perspectives, 103(9):103-114.

Morales K, Ryan L, Kuo T, Wu M, and Chen C. 2000. Risk of Internal Cancers from
       Arsenic in Drinking Water. Environmental Health Perspectives. 108(7):655-661.
                                     3-24

-------
National Toxicology Program. 2001. TR-8 Bioassay of Chlordane for Possible
       Carcinogenicity (CAS No. 57-74-9), Internet: http://ntp-server.niehs.gov/htdocs/
       LT-studies/TR008.html

Nichols KM, Miles-Richardson SR, Snyder EM, Giesy JP. 1998. Effects of Exposure to
       Municipal Wastewater In Situ on the Reproductive Physiology of the Fathead
       Minnow (Pimephales Promelas). Environmental Toxicology and Chemistry.
       18(9):2001-2012.

Nixon SW. 1998. Enriching the Sea to Death. Scientific American. 9(3):48-53.

Penrose W, Conacher H, Black R, Meranger J, Miles W, Cunningham H, and Squires W.
       1977. Implications of Inorganic/Organic Interconversion on Fluxes of Arsenic in
       Marine Food Webs. Environmental Health Perspectives. 19:53-59.

[PSR] Physicians for Social Responsibility. 2000. Drinking Water and Disease: An
       Educational Conference for Health Care and Public Health Professionals.
       Resource Packet.

Potera C. 2000. New mouse genomics consortium. Environmental Health Perspectives.
       108(10): forum.

Raloff J. 2000. More Waters Test Positive for Drugs. Science News. 157:212.

Raucher RS. 1996. Public Health and Regulatory Considerations of the Safe Drinking
       Water Act. Annual Review of Public Health.  17:179-202.

Rodgers-Gray TP, Jobling S, Morris S, Kelly C, Kirby S, Janbakhsh A, Harries JE,
       Waldock MJ, Sumpter JP and Tyler CR. 2000. Long-Term Temporal Charges in
       the Estrogenic Composition of Treated Sewage Effluent and its Biological Effects
       on Fish. Environmental Science &  Technology. 34(8):1521-1528.

Rose JB. 1997. Environmental Ecology of Cryptosporidium and Public Health
       Implications. Annual Review of Public Health. 18(1):135-161.

Rose JB, Griffin DW, and Nicosia LW. 2000. Virus Transport from Septic Tanks to
       Coastal Waters. Small Flows Quarterly.  1(3).

Rose JB, Epstein PR, Lipp EK, Sherman BH, Bernard SM, and Patz JA. 2001. Climate
       Variability and Change in the United States: Potential Impacts on Water - and
       Foodborne Diseases Caused by Microbiologic Agents. Environmental Health
       Perspectives. \ 09(2):211 -221.

[SAIC] Science Applications International Corporation. 2000. Ground Water Rule:
       Ground Water Risk Assessment. U.S. Environmental Protection Agency Office of
       Ground Water and Drinking Water.
                                     3-25

-------
Schmidt CW. 1999. Safe Food: An all-consuming issue. Environmental Health
       Perspectives. 107(3): 144.

Smith A, Hopenhayn-Rich C, Bates M, Goeden H, Hertz-Picciotto I, Duggan H, Wood R,
       Kosnett M, and Smith M. 1992. Cancer Risks from Arsenic in Drinking Water.
       Environmental Health Perspectives. 97:259-267.

Stumm W and Morgan JJ. 1981. Aquatic Chemistry: An Introduction Emphasizing
       Chemical Equilibria in Natural Waters. 2nd ed. New York: John Wiley & Sons.

Suter II GW. 1996. Guide for developing conceptual models for ecological risk
     assessments. Prepared for the U.S. Department of Energy, Office of Environmental
     Management. Oak Ridge (TN): Environmental Restoration Risk Assessment
     Program, Oak Ridge National Laboratory.

	. 1999(a). A framework for assessment of ecological risks from multiple
     activities. Human & Ecological Risk Assessment. 5:397-413.

	. 1999(b). Developing conceptual models for complex ecological risk
     assessments. Human & Ecological Risk Assessment. 5:375-396.

Suthersan SS. 2001. Natural and Enhanced Remediation Systems. Boca Raton (FL): CRC
       Press LLC.

Thomann RV. 1995. Modeling Organic Chemical Fate in Aquatic Systems: Significance
       of Bioaccumulation and Relevant Time-Space Scales. Environmental Health
       Perspectives. 103(Suppl 5):00~00.

Tibbetts J. 2000. Water World 2000. Environmental Health Perspectives. 108(2):68.

Tseng C, Tai T, Chong C, Tseng C, Lai M, Lin BJ, Chiou H, Hsueh Y, Hus K, and Chen
       C. 2000. Long-Term Arsenic Exposure and Incidence of Non-Insulin-Dependent
       Diabetes Mellitus: A Cohort Study in Arseniasis-Hyperendemic Villages in
       Taiwan. Environmental Health Perspectives. 109(9):847-851.

[US EPA] United States Environmental Protection Agency. 1989. Transport and Fate of
       Contaminants in the Subsurface. EPA/625/4-89/019. Washington (DC): US EPA.

	. 1997. Special Report on Environmental Endocrine Disruption: An Effects
       Assessment and Analysis, Prepared for the Risk Assessment Forum. EPA/630/R-
       96/012. Washington (DC): US EPA.

	. 1998(a). Guidelines for Ecological Risk Assessment. EPA/630/R-95/002F.
       Washington (DC): US EPA.
                                     3-26

-------
          .. 1998(b). Arsenic, Inorganic. CASRN 7440-38-2. EPA Integrated Risk
       Information System. Internet: http://www.epa.gov/ngispgm3/iris/subst/0278.htm

      	. 1999(a). Residual risk report to Congress. EPA-453/R-99-001. Washington
       (DC): US EPA.

      	. 1999(b). Integrated environmental decision-making in the 21st Century, a
     report from the EPA Science Advisory Board's Integrated Risk Project - Peer
     Review Draft.

     	. 1999(c). Methodology for Assessing Health Risks Associated with Multiple
     Pathways of Exposures to Combustor Emissions—Update to EPA/600/6-90/003.
     EPA 600/R-98/137. Washington (DC): US EPA

     	. 2000. Risk Characterization, Science Policy Council Handbook. EPA 100-B-
     00-002. Washington (DC): US EPA.

[US EPA-OW] United States Environmental Protection Agency, Office of Water.
     2001 (a). Drinking Water Contaminants. Internet: http://www.epa.gov/safewater/
     hfacts.html

	. 200 l(b). Update: National Listing of Fish and Wildlife Advisories. EPA-823-
     F-01-010. Washington (DC): US EPA.

     	. 2002 Drinking Water Fact Sheet on Tetrachloroethene. Internet:
     http://www.epa.gov/
     safewater/dwh/c-voc/tetrachl.html.
[USGS] United States Geological Survey. 2000. Distribution, Movement, and Fate of
       Nitrate in the Surficial Aquifer Beneath Citrus Groves, Indian River, Martin and
       St. Lucie Counties, Florida, 2000. Water Resource Investigations Report 00-4057.
       Washington (DC): USGS.

Valette-SilverNJ, Riedel GF, Crecelius EA, Windom H, Smith RG, and Dolvin SS.
       1999. Elevated arsenic concentrations in bivalves from the southeast coasts of the
       USA. Marine Environmental Research. 48:311-333.

Vom Saal FS. 1995. Environmental Estrogenic Chemicals: Their Impact on Embryonic
       Development. Human and Ecological Risk Assessment. 1(2): 1-15.

Wallace GT. and Braasch EF, eds.  1997. Proceedings of the Gulf of Maine Ecosystem
       Dynamics Scientific Symposium and Workshop. RARGO3VI Report, 97-1. Hanover
       (NH): Regional Association for Research on the Gulf of Maine.
                                     3-27

-------
Wittman RJ and Flick GL. 1995. Microbial Contamination of Shellfish: Prevalence, Risk
       to Human Health, and Control Strategies. Annual Review of Public Health.
       16(1):123-140.

Woolson E. 1977. Fate of Arsenicals in Different Environmental Substrates.
       Environmental Health Perspectives. 19:73-81.

York DW, Menendez P and Walker-Coleman L. 2002. Pathogens in reclaimed water: the
       Florida experience. 2002 Water Sources Conference.
                                     3-28

-------
4.0    DEEP-WELL INJECTION

In this chapter, human health and ecological risks associated with the deep-well injection
wastewater management option are described and evaluated. Sources of data and
information are used to develop a conceptual model of potential risks. A wastewater fate
and transport analysis examines the factors that may be most important in determining
risk and levels of risk. This evaluation results in a refined final conceptual model that
describes the risks that are most probable.

4.1    Definition of the Deep-Well Injection Option

Deep wells are used in South Florida to dispose of secondary-treated municipal
wastewater. These wells are permitted as Class I municipal wells, which by definition
dispose of wastewater beneath the lowermost formations containing, within a minimum
of one-quarter mile of the well bore, an underground source of drinking water (USDW)
(FDEP, 1999a). Deep municipal wells in South Florida inject at depths ranging from
approximately 1,000 feet to greater than 2,500 feet below surface of the land.

4.2    Deep-Well Capacity and Use in South Florida

Class I injection wells are used in various regions of the United States for disposal of
hazardous and nonhazardous fluids. In South Florida, they provide an important means of
managing treated municipal wastewater. The Florida Department of Environmental
Protection (DEP) estimates that deep-well injection accounts for approximately 20%
(0.44 billion gallons per day) of the total wastewater management capacity in the State of
Florida (FDEP, June 1997).

Although deep-well injection is practiced throughout much of South Florida, these wells
are concentrated in southeastern portions of the State and in the coastal areas (Figure 4-1;
Figure 2-2; Appendix Table 1-6). Dade, Pinellas, and Brevard counties serve as three
areas of focus for this risk analysis and are at three corners of the triangular study area.
These counties present unique geologic environments and differences in injection system
operation that may have a substantial bearing on risk.

4.3    Environment into Which Treated Wastewater is Discharged

To evaluate risk, it is critical to understand regional variations in geology and
hydrogeology that influence subsurface fate and transport of injected wastewater.
Hydrogeologic units vary in thickness and in their characteristics (for example, porosity
and conductivity) across various regions of South Florida. A description of the
hydrologic system and hydrogeologic units in South Florida is provided below.

Hydraulic conductivity ("K") is a measure of a formation's capability to transmit water
under pressure. Aquifer units or layers that exhibit low hydraulic conductivity typically
slow the rate at which groundwater flows.
                                       4-1

-------
                                                             Duval \  Jacksonville
                                                                          Seminole
            Plugged  Proposed Easing   Type
                                   Combined Municipal
                                   & NonMunicipal
                                                                                     Miami
Figure 4-1.  Locations of Class I Injection Wells in South Florida
                                         4-2

-------
The hydrogeologic system throughout much of South Florida consists of thick sequences
of carbonate rocks overlain by clastic deposits (Tibbals, 1990; Broska and Barnette,
1999; Tihansky and Knochenmus, 2001). Three hydrogeologic features are common to
Dade, Pinellas and Brevard counties: the presence of a relatively shallow surficial aquifer
(called the Biscayne Aquifer in Dade County), the presence of a unit with lower relative
hydraulic conductivity (the intermediate confining unit), and the presence of the Floridan
Aquifer System. Figure 4-2 presents representative hydrogeologic cross sections that
illustrate these and other features in the three counties.

The surficial aquifer (and the Biscayne Aquifer in Dade County) represents the
uppermost hydrogeologic unit. These shallow aquifers lie above sequences exhibiting
lower relative hydraulic conductivity (the intermediate confining unit) which, in turn,
overlie the Floridan Aquifer System. The Floridan Aquifer System is divided into three
distinct units, referred to as the Upper Floridan Aquifer, the middle confining unit, and
the Lower Floridan Aquifer. Each of these aquifers is described in more detail below.

Deep-well injection is conducted within the Lower Floridan Aquifer in Dade and Brevard
counties and within the Upper Floridan Aquifer in Pinellas County (Hutchinson, 1991;
Hickey, 1982; Florida Department of Regulation, 1989; FDEP, 1999a).

4.3.1   Aquifers in South Florida

The Biscayne and surficial aquifers are the uppermost aquifers in  South Florida. The
surficial aquifer is composed of relatively thin layers of sands with some interbedded
shells and limestone. Thickness of the surficial aquifer ranges from 20 to 800 feet, with
the greatest thickness occurring in southeastern Florida (Adams, 1992; Barr, 1996;
Lukasiewicz and Adams, 1996; Reese and Cunningham, 2000). The surficial aquifer
yields relatively small volumes of water and is thus of limited use for public water
supply; however, it is an important source of private water supplies (Miller, 1997).

The Biscayne Aquifer is the only formally named surficial aquifer unit in South Florida.
The Biscayne Aquifer is the principal source of drinking water in Dade County. This
aquifer extends along the eastern coast from southern Dade County into coastal Palm
Beach County. The Biscayne Aquifer varies in thickness from a few feet to 240 feet and
is composed of highly permeable limestone or calcareous  sandstone (Meyer, 1989;
Reese, 1994; Maliva and Walker, 1998; Reese and Memburg, 1999; Reese and
Cunningham, 2000).

The intermediate confining unit lies beneath the surficial aquifers  in Dade, Pinellas, and
Brevard counties. Thick upper and lower clay layers confine depositional layers within
this aquifer and limit, but do not eliminate the aquifer's hydraulic  conductivity (Miller,
1997).
                                       4-3

-------
The intermediate confining unit consists of sedimentary deposits from the Arcadia
Formation of the upper Hawthorn Group and the Tamiami Formation. Figure 4-3 presents
a geologic profile of South Florida. Unit thickness varies across a broad range, with the
greatest unit thickness generally occurring in southeast Florida. Sedimentary layers are
composed mostly of sand, sandy-limestone, and shell beds, with interlayered dolomite
and clayey beds.

The intermediate confining unit is characterized by low hydraulic conductivity and acts
as a confining unit, preventing or slowing migration between the overlying surficial
aquifer and the underlying Floridan Aquifer System (Duerr and Enos, 1991; Barr, 1996;
Knochenmus and Bowman, 1998). Similarly, the intermediate confining unit present in
Dade County separates the Biscayne Aquifer from the Floridan Aquifer System.

The Floridan Aquifer System is subdivided into three distinct hydrogeologic units: the
Upper Floridan Aquifer, the middle confining unit, and the Lower Floridan Aquifer. In
general, the rocks of the Upper and Lower Floridan Aquifers consist of fractured and
karstified limestones and dolomites of varying but generally high permeability. The
hydrologic units of the Upper Floridan Aquifer correlate to the geologic units identified
as the Suwannee Limestone, the Ocala Limestone, and the upper portion of the Avon
Park Formation. The portions of the Upper Floridan Aquifer that yield lower amounts of
water are typically associated with the Avon Park Formation (Hickey, 1982; Hutchinson,
1991; Hutchinson and Trommer, 1992; Reese, 1994).

The Upper and Lower Floridan Aquifers are separated by the middle confining unit,
which contains lower-permeability rocks and clays (Meyer, 1989; Tibbals, 1990; Duncan
et al., 1994; Reese, 1994; Reese and Memburg, 1999). The middle confining unit is
comprised of rocks from the lower portion of the Avon Park Formation and upper part of
the underlying Oldsmar Formation. These rocks consist of low-permeability clays, fine-
grained limestones, and anhydrous dolomite, ranging in thickness across South Florida
from 900 to  1,100 feet (Bush and Johnston, 1988; Duncan et al., 1994; Miller, 1997;
Reese and Memburg, 1999).

The Lower Floridan Aquifer consists of three distinct layers within one depositional unit.
The upper portion of this aquifer consists of dolostones and limestones of the Upper
Oldsmar Formation (Duncan et al., 1994). The middle portion is commonly referred to as
the Boulder Zone and consists of heavily karstified limestone and dolomite (Duncan et
al., 1994; Maliva and Walker,  1998). Below this middle portion, the Lower Floridan
Aquifer has properties that are largely consistent with the upper portion of the aquifer.

Within the Boulder Zone, solution channels, fractures, and widened joints allow
channelized groundwater flow, sometimes at extremely rapid rates. Flow through
fractures, solution channels, or other large voids are referred to as bulk flow through
preferential flow paths, fracture flow, or channel flow.
                                      4-4

-------
               Intermediate
       Shallow    Monitoring
     Monitoring —,   Well      Deep
          Well
     Injection
       Well
  Deep
Monitoring
  Well
diate
ring
I      Deep
    Injection
  „    Well
  Deep
Monitoring
  Well
                                                                                -nn-    Surficial
                                                                                110    Aquifer
                                                                                        Upper
                                                                                325'    Floridan
                                                                                       Aquifer
                                                                                        Middle
                                                                                335'  Confining
                                                                                         Unit

                •  '  V i'	r1  r
                     Pinellas County, Florida
1500'
2000'-
                                                  Brevard County, Florida
   Figure 4-2.  Representative Hydrogeoloj

-------

-------
                                                                  North-northwest
                                             South-southwest
                                                                                                                                  B1
   EXPLANATION
13] UPPER CONFINING UNIT
[31 IIIGMLYPEWEABLE ROCKS
Qj MiCDLE CONFINING UNIT
gH IOCAL CONFINING BE F>
0t] BOULDER ZONE
Q LOWER CONriNINS UNIT
—- NO DATA
                                                                                                                                  50 KILOMETERS
                                                                                               T«itary
                                                                                               Posl M
                                                                                                                            Sourcei UcPherson et al (2000)
Figure 4-D.  "eologic  GroDile on South Florida

-------
Some reports indicate that groundwater flow in the Upper Oldsmar Formation is
consistent with flow through porous media, with little or no channel flow (Meyer, 1989;
Duncan et al., 1994; Maliva and Walker, 1998). This type of porous media flow through
fine, interconnected pore spaces is typically less rapid than channel flow.

Representative values for hydraulic conductivity, porosity and thickness for each of the
aquifer units in Dade, Brevard, and Pinellas counties are presented in the following
sections. Mean (weighted) values are based on a statistical analysis of data reported in the
scientific literature. Primary and secondary values of porosity and hydraulic conductivity
are presented; these are used to examine flow through porous and fractured media,
respectively.

4.3.2  Regional Conditions in Dade County

All documented deep-well injection in Dade County occurs within the Boulder Zone of
the Lower Floridan Aquifer (Meyer, 1984, Duncan et al., 1994; Maliva and Walker,
1998). Typically, injection wells discharge within the top 250 to 300 feet of the Boulder
Zone (FDEP, 1999a). In Dade County, this results in injection into saline groundwater at
approximately 2,750 feet below the land surface. The base of the USDW is located
approximately 990 feet above the  injection zone, within the Upper Floridan Aquifer
(Duerr,  1995) (Figure 4-2). Table  4-1 displays the representative values for hydraulic
conductivity, porosity, and thickness for the aquifer units in Dade County.
                                       4-8

-------
Table 4-1.    Dade County: Representative (Weighted Average) Hydraulic
              Conductivity, Porosity, and Thickness of Hydrologic Units
Hydrologic
Unit or
Subunit
Biscayne
Aquifer
Intermediate
Confining
Unit
Upper
Floridan
Aquifer
Middle
Confining
Unit
Lower
Floridan
Aquifer
Boulder Zone
Hydraulic Conductivity (ft/day)
Horizontal
1,524
90
42
4.7
0.01
6,540
Primary1
Vertical
15
0.1
0.42
0.04
0.1
65
Secondary2
Vertical
15
2.38
2.38
1.50
0.1
65
Porosity
Primary1
0.31
0.31
0.32
0.43
0.4
0.2
Secondary2
0.31
0.1
0.1
0.1
0.1
0.2
Approx.
Depth
(ft below
land
surface)
0-230
230 - 840
840-
2,060
2,060 -
2,550
2,550-
2,750
2,750 -
>3,250
Unit
Thickness
(ft)
230
610
1,220
490
200 3
500
Note: Descriptions of the statistical methods and literature-derived data are provided in Appendices 2 and 3.
1 Primary values are used in scenario 1: flow through porous media.
2 Secondary values are used in scenario 2: bulk flow through preferential flow paths.
3 The Lower Floridan Aquifer extends below the Boulder Zone; this value for thickness represents only the portion
  above the Boulder Zone.
4.3.3  Regional Conditions in Pin el I us County

Deep-well injection in Pinellas County is conducted in the Upper Floridan Aquifer,
within the more permeable upper portion of the Avon Park Formation (Hickey, 1982;
Hutchinson, 1991). Typically, injection wells discharge within the uppermost 100 to 300
feet of the Avon Park Formation (FDEP, 1989), approximately 1,250 feet below land
surface (Figure 4-2). Wastewater is injected below the base of the USDW into
moderately saline groundwater that has total dissolved solids (TDS) concentrations of
20,000 milligrams per liter (mg/L) (Hickey, 1982; Hutchinson, 1991). The base of the
USDW is located approximately 570 feet above the injection zone, which is still within
the Upper Floridan Aquifer (Duerr, 1995). Table 4-2 displays the representative values
for hydraulic conductivity, porosity, and thickness for the aquifer units in Pinellas
County.
                                         4-9

-------
Table 4-2.    Pineilas County: Representative (Weighted Average) Hydraulic
              Conductivity, Porosity and Thickness of Hydrologic
Hydrologic
Unit or
Subunit
Surficial
Aquifer
Intermediate
Confining
Unit
Upper
Floridan
Aquifer
Hydraulic Conductivity (ft/day)
Horizontal
29
4
22
Primary1
Vertical
7
1.2
0.3
Secondary2
Vertical
7
1.5
0.3
Porosity
Primary1
0.31
0.31
0,23
Secondary2
0.31
0.1
0.1
Approx.
Depth
(ft below
land
surface)
0-56
56 - 275
275-
2,223
Unit
Thickness
(ft)
56
219
1,948
Note: Descriptions of the statistical methods and literature-derived data are provided in Appendices 2 and 3.
1 Primary values are used in scenario 1: flow through porous media.
2 Secondary values are used in scenario 2: bulk flow through preferential flow paths.
4.3.4  Regional Conditions in Brevard County

Deep-well injection in Brevard County occurs within the Lower Floridan Aquifer,
approximately 2,500 feet below land surface. The base of the USDW is also located in
the Lower Floridan Aquifer, approximately 1,500 feet below the land's surface and 950
feet above the injection zone (Duerr, 1995). The middle confining unit acts as a
hydrologic barrier that separates and hydrologicly confines the Lower Floridan Aquifer
from the Upper Floridan Aquifer (Figure 4-2). Table 4-3 displays the representative
values for hydraulic conductivity, porosity, and thickness for the aquifer units in Brevard
County.
                                        4-10

-------
 Table 4-3.    Brevard County: Representative (Weighted Average) Hydraulic
              Conductivity, Porosity and Thickness of Hydrologic Units
Hydrologic
Unit or
Subunit
Surficial
Aquifer
Intermediate
Confining
Unit
Upper
Floridan
Aquifer
Middle
Confining
Unit
Lower
Floridan
Aquifer
Boulder Zone
Hydraulic Conductivity (ft/day)
Horizontal
56
20
20
0.8
0.1
650
Primary1
Vertical
13
0.1
0.2
0.04
0.1
65
Secondary2
Vertical
13
2.38
2.38
1.50
0.1
65
Porosity
Primary1
0.31
0.31
0.26
0.43
0.4
0.2
Secondary2
0.31
0.1
0.1
0.1
0.1
0.2
Approx.
Depth
(ft below
land
surface)
0-130
130-340
340 - 665
665-
1,000
1,000-
2,460
2,460-
>2,754
Unit
Thickness
(ft)
130
210
325
335
1,4603
294
Note: Descriptions of the statistical methods and literature-derived data are provided in Appendices 2 and 3.
1 Primary values are used in scenario 1: flow through porous media.
2 Secondary values are used in scenario 2: bulk flow through preferential flow paths.
3 The Lower Floridau Aquifer extends below the Boulder Zone; this value for thickness represents only the portion
  above the Boulder Zone.
4.4    Groundwater Quality and Fluid Movement in South Florida

Deep-well injection facilities in South Florida conduct routine sampling and analysis of
groundwater taken from units overlying injection zones. This information may be used to
identify instances of apparent unintended movement of fluids from the injection zone,
occurring now or in the past, although the monitoring wells are located near the injection
wells and would not be capable of indicating the areal extent of the contamination.

There were few data collected to characterize the quality of deep groundwater resources
in South Florida prior to construction and operation of injection wells. The U.S.
Geological Service conducted a study of the water resources in Dade County prior to well
completion and commencement of operations (Earle and Meyer,  1973). The study
showed chloride concentrations between 15 and 14,500 mg/L.

Data are available for characterizing the quality of groundwater resources since injection-
well construction and operation began. Englehardt et al. (2001) compiled a limited data
set that includes information about the levels of inorganic contaminants present in lower
and upper native (or ambient) groundwater monitoring zones (Appendix Table 1-1).
Though it cannot be said conclusively that these data characterize preoperation
                                        4-11

-------
conditions, the data are sufficient for illustrating two points. First, deep native
groundwater in southeast Florida does appear to exceed several primary or secondary
drinking-water standards (maximum contaminant levels, or MCLs). Second, for some
contaminants (for example, cadmium, lead, antimony, aluminum, iron), there is reason to
conclude that these levels are of natural origin (resulting, for example, from the
dissolution of the native aquifer matrix) and not attributable to any aspect of well
construction or operation. For some other contaminants (for example, thallium,
beryllium), it is less clear why there are slightly elevated levels present in upper and
lower groundwater monitoring zones.

The Florida DEP has compiled groundwater monitoring information collected during
construction and operation of deep-injection wells. Florida DEP has used this information
to develop a map (reproduced as Figure 4-4) that depicts fluid movement associated with
deep-injection wells throughout South Florida. This map identifies facilities where
confirmed and probable fluid movement has occurred and specifies whether this
movement is into a USDW or non-USDW (FDEP, 2002). Non-USDWs are used in this
figure to depict wells with movement into aquifers containing groundwater of greater
than 10,000 mg/L TDS concentration.

The Florida DEP has concluded that approximately three deep-well injection sites in
Pinellas, Dade, and Palm Beach counties have caused confirmed fluid movement into
USDWs (Figure 4-4). An additional six deep-well injection facilities in Pinellas and
Brevard counties have caused probable fluid movement into USDWs. As many as nine
additional facilities have caused fluid movement into non-USDWs, predominantly in
Broward County (Figure 4-4).

Approximately 18 deep-well injection facilities appear to be associated with some form
of unintended fluid movement from the injection zone. Deep-well injection facilities in
many other parts of South Florida do not appear to have caused unintended fluid
movement. Multiple facilities in each of several counties (Charlotte, Collier, Lee,
Sarasota, and St. Lucie counties) have operated for years with no apparent fluid
movement.

The sections that follow present data and information specific to Dade, Pinellas, and
Brevard counties. These sections present information made available through exhaustive
data collection efforts and the close cooperation of Florida DEP and water utilities in
South Florida. These sections do not provide the same types and amounts of data for each
county. The data and information do, however, serve as a means of better understanding
what is known about the condition of groundwater resources, changes in water quality,
and the occurrence of confirmed or probable fluid movement in South Florida.
                                      4-12

-------
                                                                     Class 1  Injection Facilities
Plugged      Proposed

  3        O
                                                                                                                                       No !-\v;-(i mnvsmsff

                                                                                                                                       Fluid movement into non-USDW

                                                                                                                                       Fluid iTiOviMrfeit p"ib*ib!y into S.ISOW

                                                                                                                                                    into US£3W
•                                                                                                                                       Ruki movement above injection zor.s

                                                                                                                                       Plugged and abandoned
                                         Combined Municipal 8 Nonmunicipal
                       Class I  Facilities
                                 Sunset Park
                                 Kendale takes
                                 Miemt-Oade South District Reg-
                                 Broward County • North District Reg.
                                 Basparilte Island RO
                                 North Martin County
                                 Seacoast Utilities
                                 East Port
                                 Melbourne-Grant Street
                                 City of Saratota (enpioratoiy)
                                 Pahokee
                                 Belle Glade
                                 Fort Myers Beach
                                 Charlotte County West Port
          1. Sdutia {Monsanto)
          2. Storting Fitters (Cytac)
          3. NW Pinellu County (exploratory)
          4. Clearwater East
          5. St. Petersburg ME
          6. Albert Whined
          7. McKay Creek
          fl. Soulh CtotB Bayou
          9. St. Petersburg NW
         10. St. Petersburg 5W
         11. Kaiser
         12. Manatee County SW
         13. Atlantic Utilities
         14. Miami-Dade North District Reg.
         15. Knight's Trail Par* RO (exploratory)
         18. Venice Gardens RO
         17. EnglewoodRO
         1B. Plantation RO (SB resets CO)
         IB. GsEpBrilla Island
         20. North Port
         21. North Fort Myers
         22. Gutf Environmenlal Services
         23. Syttes Creek (Meiritt Island)
         24. Wesl Mel bourne
         25. Malbouma-O.B. Lee
         26. Interct! (Harris CorpwationJ
         27. Palm Bey (GDU-Port Malabar)
         26. South Beaches
         29. Ocean Spray (H«rcules)
         30. North Port St. tucie
         31. South Port St Lucia
         32. Stuart
         33, Pratt & Whitney
         34.Q.O. Crtemicals
         35, Encon
         36. Palm Soacti County RRF
         37, East-Central Regional
         33. Acme Improvement Disl
         39. Palm Beach Co. Sys. #3
         40. Palm Beach Co. Sys. *9
         41. Coral Springs Improvement Dist.
         42. Margate
         43. Royal Palm Qeach
         44. Sunrise
         45. Plantation Utilities
         46. G.T, Lohmeyer
         47. Pembroke Pines (Century Wage)
                                 Palm Beach Co. Southern Regional
                                 Plantation East RO
                                 Burnt Store
                                 Boynton Beach RO
                                 Plantation RO (Broward Co.)
                                 Marco Island RO
                                 North Collier County
                                 Zemel Road Landfill
                                 Hollywood
                                 Serasota County Center Road
                                 Fort Pierce Utilities Auin.
                                 Miramar RO
                                 Sanibal Island
                                 Miramar
                                 Venice Gardens Eest
                                 South. Collier County
                                 Sunrise Sawgrass RO
                                 Port St. Lucis Western VvTP
                                 Cooper CHyRO
                                 Fort Myers RO
                                 PunlaGorda
                                 Poinpano Basch RO
                                 tmmokeiee
                                 Soulh Cofiiar County RO
                                 Fort Pierce RO
                                 Bontta Springs RO
                                 PortSlt-ucieWestoort
                                 North ColBer County WRF
                                 Bontts Springs WRF
                                 Palm Bay RO (Exptoralory)
                                 CPV Cans Power Plant
Miles
Figure 4-4.   Fluid  Movement Associated with Class I Deep Well  Injection  Facilities  in South  Florida

-------
Analytical parameters widely used as indicators of fluid movement include dissolved
ammonia, TDS, chloride, and fecal coliforms. Dissolved ammonia (or ammonium) is
present in secondary-treated wastewater but is not typically found in native groundwater.
Levels of chloride and TDS indicate if there has been a "freshening" of naturally saline
native groundwater, which may suggest fluid migration of treated wastewater. Dissolved
chloride is present at very low concentrations in treated wastewater but occurs at very
high concentrations in Florida's deep aquifers; reaching concentrations similar to
seawater (20,000 to 30,000 mg/L). Detection of relatively "fresh" water (low chloride or
TDS concentrations) in deep monitoring wells may be interpreted as evidence of fluid
movement.

Fecal coliforms are present in secondary-treated wastewater at varying concentrations,
depending upon whether or not the wastewater has undergone basic disinfection.
(Secondary treated wastewater that has undergone basic disinfection may still contain
concentrations of fecal coliforms; see Appendix 1.) Most fecal coliform strains are not
pathogenic and are used only as indicators for the presence of other pathogenic
microorganisms. Chapter 3 discusses pathogenic strains such as E. coli and examines
some of the issues related to use of fecal coliforms as an indicator.

4.4.1   Bade County Groundwater Monitoring Information

Much of the groundwater monitoring information available for Dade County concerns the
South District Wastewater Treatment Plant (SDWWTP), where  there has been confirmed
fluid movement into the USDW. Data and information obtained from monitoring wells at
this facility provide evidence that upward migration of injected wastewater has occurred.

The SDWWTP uses 17 deep-injection wells, of which 13 are currently permitted for
injection. Monitoring wells associated with each deep-injection  well were constructed to
monitor the Upper Floridan Aquifer, typically at two depths. Most monitoring wells at
the site monitor zones at 1,500 feet and 1,800 feet below surface. The first of these zones
represents the base of the lowermost USDW. Monitoring of the  1,800-foot zone provides
an early warning of fluid movement and contamination below the base of the USDW.

Elevated concentrations of ammonia have been detected in monitoring wells at both the
1,500-  and 1,800-foot zone. Elevated concentrations  of dissolved chlorides have also
been detected; these may indicate displacement of native formation water in an upward
direction. Fecal coliforms have been detected in a number of monitoring wells.

In 1996, monitoring wells (FA-14 through FA-16) began to detect elevated ammonia
concentrations in the  1,500-foot zone.  Beginning in 1998, two of these wells, those
nearest to a well suspected of mechanical failure (BZ-1), were purged of millions of
gallons of water. This was initially accomplished by allowing them to flow freely by
artesian pressure. Pumps were subsequently installed to increase the flow rate.

A purging report from December 1998 (SDWWTP, 1998) indicates that there was a
slight decrease in the concentrations of ammonia detected by monitoring well FA-16 in
                                      4-14

-------
response to purging. In another well, FA-15, there was a larger drop in ammonia
concentrations after purging but subsequently these concentrations stabilized at a lower,
but still elevated, level. Detected levels of ammonia were higher than background levels
for these depths, and as such, were interpreted as an indicator of potential contamination
resulting from movement of injected fluids.

In 1994, around the time when chloride anomalies were first noticed in BZ-1, ammonia
was detected in water taken from the 1,500-foot monitoring zone in newly constructed
monitoring wells FA-5 though FA-8 (adjacent to newly constructed injection wells IW-
13 through IW-16). The first samples taken from FA-5 through FA-8, soon after
completion in 1994, showed elevated concentrations of ammonia.

Monitoring well FA-5 was purged between 1996 and 1998. Ammonia concentrations
decreased by 43% during purging. When purging stopped, ammonia levels returned to
approximately the same concentrations as were present before purging.

Elevated ammonia concentrations were detected in monitoring wells placed in the 1,800-
foot zone (including wells FA-11 and FA-12) when these wells were first used to perform
monitoring (February 1996). These wells were included in the purging program with little
apparent impact to monitored ammonia concentrations. Monitoring has continued to
detect elevated ammonia concentrations in these wells.

The authors of this report (SDWWTP, 1998) were unable to determine whether elevated
ammonia levels existed as part of a finite volume of water or whether there was a
continuous source. There has been no information to attribute elevated levels of ammonia
in the areas surrounding FA-5  through FA-8 to conduits created by injection activities at
the site. In 1994, there were no known anthropogenic conduits ("artificial penetrations")
between the Boulder Zone and the 1,500-foot zone close to these monitoring wells. In
1994, there were no wells in this part of the facility suspected of having faulty
construction and no other operational problems.

An injection well, IW-2, near FA-11 and FA-12, may have  contributed to movement of
fluid from the injection zone to the 1,800-foot monitoring zone. However, periodic tests
of this well (radioactive tracer surveys, a temperature survey, and television survey of
inside the well bore) have failed repeatedly to identify any well construction problems
above 2,500 ft.

The SDWWTP purging report also provides information on concentrations of fecal
coliforms detected in groundwater between  1987 and 1995 (SDWWTP, 1998). For many
wells and sampling dates, monitoring data indicate groundwater concentrations below the
detect level (Appendix Table 1-5). Low concentrations of fecal coliform contamination
(for example, tens of colonies per 100 milliliters (mL)) have been detected with roughly
twice the frequency of higher concentrations. High concentrations (for example, several
hundred colonies per 100 mL and, in one instance, greater than 2,000 colonies per 100
mL) were occasionally detected in groundwater, generally at depths of approximately
1,000 feet (Appendix Table 1-5).
                                      4-15

-------
Episodes of high fecal coliform contamination appear to have been most frequent during
1992 and, to a lesser extent, during 1993 and 1994 (Appendix Table 1-5). In 1995, the
SDWWTP disinfected a number of monitoring wells. Following disinfection, there were
fewer fecal coliform detections in groundwater, and only low concentrations were
detected.

4.4.2   Pinellas County Groundwater Monitoring Information

Groundwater monitoring information is available in Pinellas County for the City of St.
Petersburg facilities, where there has been probable fluid movement (and, in one case,
confirmed fluid movement) into USDWs. Data and information obtained from
monitoring wells at these facilities provide evidence  that upward migration of injected
wastewater has occurred. A review of this information follows.

The four St. Petersburg wastewater reclamation facilities (WWRFs) treat wastewater to
reclaimed standards and provide high-level disinfection. Reclaimed wastewater that is not
used by the reuse system (either because its volume exceeds current demands or because
it does not meet stringent quality standards) is pumped into the middle and  lower portions
of the Upper Floridan Aquifer via 10 deep-injection wells. Injection zones in southern
Pinellas County contain water with a high TDS content; these injection zones are not
classified as USDWs.

The 2000 Annual Summary Report for St. Petersburg's four injection facilities (CH2M
Hill, 2001) provides evidence that upward migration of injected wastewater has occurred
over the 20 years since injection operations first began. Monitoring data reveal that, at
more than one of these facilities, there has been significant change in water quality both
below and within USDWs.

At the Albert Whitted facility, the largest of the St. Petersburg facilities, water-quality
profiles reveal significantly altered water quality above the injection zone. In  1989,
background pre-injection TDS concentrations ranged from less than 2,700 mg/L at
approximately 250 feet to 35,000 mg/L in the injection zone at 700 feet. (The 250-foot
zone is both a USDW and part of the Upper Floridan Aquifer.) Once injection operations
commenced, monitoring detected TDS concentrations greater than 7,400 mg/L within the
USDW in 1993  before these concentrations declined to approximately 1,700 mg/L in
2000. At 375  feet, near the base of the USDW, TDS  increased from 6,300 mg/L in 1986
to more than  15,000 mg/L in 1989. TDS then declined to 1,500 mg/L in 2000 (CH2M
Hill, 2001). The most likely reason for these trends is that comparatively fresh and
buoyant injectate has pushed highly saline formation waters upward into USDWs.

Ammonia concentrations detected within the 550-foot zone at the Albert Whitted facility
have increased from as low as 0.4 mg/L in 1986 to as high as 17.8 mg/L in  1999 (CH2M
Hill, 2001). These increases have coincided with observed decreases in TDS
concentration.
                                      4-16

-------
A similar situation appears to have occurred at the Northeast WWRF. A single
monitoring well completed into the USDW at approximately 150 feet has detected
significant changes in TDS concentration. TDS levels increased from as low as 1,280
mg/L in 1980 to as high as 24,000 mg/L in 2000 data (CH2M Hill, 2001). Decreasing
TDS levels have been detected in monitoring wells placed below the USDW.

At the Northwest WWRF, there is just one monitoring well, placed below the base of the
lowermost USDW. Since 1985, monitored TDS levels have fluctuated widely.
Concentrations decreased slightly from an initial concentration of 11,100 mg/L, then
increased to over 20,000 mg/L, and finally decreasing to as low as 9,300 mg/L in 2000
(CH2M Hill, 2001). Data for this facility are sparse and difficult to interpret, but the trend
appears to be consistent with data from the Northeast WWRF and the Albert Whitted
facility.

At the Southwest WWRF, several wells that monitor non-USDWs have detected
significant decreases in TDS concentration. One well that monitors water quality within
the USDW at approximately 320 feet has detected increases in TDS concentration from
5,000 mg/L in  1979 to more than 11,000 mg/L in 2000 (CH2M Hill, 2001).

Data sets for the Northeast, Northwest, and Southwest facilities are not as complete as
those available for the Albert Whitted facility. Nevertheless, it does appear that these
WWRFs are experiencing a similar displacement  of higher-salinity groundwater in an
upwards direction by injected wastewater. This displacement may be occurring at a
slower rate than has occurred at the Albert Whitted WWRF. There is some evidence at
the Northeast, Northwest, and Southwest facilities that ammonia concentrations are
increasing in the same zones that are experiencing declines in TDS concentration.

In 1993, the City of St. Petersburg initiated  a program to identify and monitor offsite
wells. Although most wells appear to be at shallow depths, private water-supply wells as
deep as 200 feet have been identified near the facilities. It is believed that all wells are
completed into a USDW and that these wells provide water primarily for irrigation. The
2000 Annual Summary Report indicates that monitored parameters (TDS, chlorides,
sodium, conductivity) are within the range of unimpacted waters (CH2M Hill,  2001). No
sampling data are included to substantiate these statements.

4.4.3  Brevard County Groundwater Monitoring Information

4.4.3.1 South Beaches

At the South Beaches facility in Brevard County,  it is probable that there has been fluid
movement into the overlying USDW. Data and information obtained from monitoring
wells at this facility provide evidence that upward migration of injected wastewater into
the USDW may have occurred.

A 2001 report prepared for the South Beaches facility (COM, 2001) includes ground-
water monitoring data for three monitoring wells at the site. A shallow well,  MW-1,
                                      4-17

-------
monitors the Ocala formation from 300 to 350 feet. Well MW-3, placed at an
intermediate depth, monitors the middle of the Upper Floridan Aquifer from 1,200 feet to
1,320 feet. A deep well, MW-2, monitors the lower part of the Upper Floridan Aquifer
from 1,550 feet to 1,700 feet.

The deep well, MW-2, monitors below the lowermost USDW where significant changes
in water quality occurred between 1987 and 2001. Conductivity and concentrations of
chloride and TDS decreased rapidly for the first several years after commencement of
injection operations. In recent years, these concentrations have stabilized (CDM, 2001).

Nitrate concentrations have remained fairly constant, just at the detectable level.
Ammonia concentrations, initially at approximately 2 mg/L, increased slightly in 1991,
but steadily decreased thereafter to 2001 levels at approximately 0.5 mg/L. Between 1987
and July of 1991, total Kjeldahl nitrogen (TK.N) increased slightly to approximately 3
mg/L, at which time it began to decrease. Detected concentrations of TKN are now
similar to the original ambient concentration of approximately 0.5 mg/L (CDM, 2001).

MW-3, the intermediate monitoring well, was constructed at a later date than the other
two wells; monitoring began in  1990. Since  1991, detected concentrations of TDS have
increased from approximately 3,500 mg/L to nearly 10,000 mg/L. Moderate increases in
the concentration of chloride, increases in conductivity, and a slight increase in ammonia
have also been observed. There has been no apparent change in the detected levels of
nitrate and TKN.

Monitoring data from the shallow well, MW-1, indicate that groundwater quality has
remained unchanged over the course of injection operations. This suggests that fluid
movement has not reached these shallow depths (300 to 350 feet).

4.4.3.2 Palm Bay

The Port Malabar Wastewater Treatment Plant  in Brevard County injects reclaimed
wastewater at approximately 3,000 feet. Test wells monitor the Lower Floridan Aquifer
at 1,534 to 1,650 feet and the shallower Upper Floridan Aquifer at 400 to 472 feet.
Injection began in 1987; monitoring results were available for some parameters
beginning in 1988 (HAI, 2000).

Monitoring performed in the deep interval reveals that nitrate and ammonia
concentrations have varied widely, but not with any apparent increasing or decreasing
trends. TDS concentrations have fallen from approximately  20,000 mg/L to
approximately 15,000 mg/L. Chloride showed a slightly increasing trend from
approximately 10,000 mg/L to 12,000 mg/L (HAI, 2000). No appreciable changes in
TDS, chloride, nitrate, or ammonia have been detected  in the shallow interval.
                                      4-18

-------
4.5    Regulations and Requirements for the Deep-Well Injection Option

The siting, construction, operation, and management of deep-injection wells are governed
by a number of Federal and State regulations, which are summarized below.

Class I injection wells are prohibited from causing the movement of any fluid into
USDWs. These are defined as aquifers, or portions of aquifers, having a sufficient
quantity of groundwater to supply a public water system, and containing a TDS
concentration of less than 10,000 mg/L (40 CFR 144.3, Florida Administrative Code
(FAC) 62-520.410(1), and FAC 62-528.200(60)). However, this definition does not
include aquifers, or portions of aquifers, that have been specifically exempted from this
regulatory definition.

40 CFR 144.12 (b) and FAC 62-528.110(2) apply specifically to Class I injection and
prohibit the movement of any contaminant into USDWs. This prohibition has been
established as a means of ensuring that no Class I injection practices are allowed to
endanger USDWs, as required by the Safe Drinking Water Act.

Criteria and standards for the construction, operation, and monitoring of nonhazardous
Class I injection wells are given in 40 CFR Part 146 (Subpart B). 40 CFR 146.12 (b) and
FAC 62-528.410(1) require that Class I wells be cased and cemented to prevent the
movement of fluids into or between USDWs. 40 CFR 146.13(a)(l) and FAC 62-
528.415(1) further state that injection pressures may not initiate fractures in the confining
zone or cause the movement of injection  or formation fluids into a USDW.

State of Florida permit requirements for Class I injection wells are defined by FAC
Chapter 62-528, Underground Injection Control (FDEP, 1999b). Requirements include
specifications for well construction, for defining hydrologic conditions relative to the site,
for ensuring mechanical integrity of injection wells, and for proper well operation.

Construction requirements for Class I wells are set forth in 40 CFR  146.12 and FAC 62-
528.410. State requirements, at FAC 62-528.425 and 62-528.300 (6), regulate mechanical
integrity of injection wells (FDEP, 1999b). Operating requirements are set forth in 40
CFR 146.13(a) and FAC 62-528.415. Monitoring requirements are set forth in 40 CFR
146.13(b) and FAC 62-528.425.

Two additional sets of requirements apply to Class I nonhazardous wells in Florida. FAC
62-600.540(4) requires certain types of surface equipment at all injection-well facilities.
Facilities must also comply with FAC 62-600, Domestic Wastewater Facilities (FDEP,
1996).

In Florida, Class I wells injecting treated wastewater into Class G-IV waters must provide
secondary treatment, at a minimum, and must meet pH limitations. Class G-IV waters are
defined as groundwater  for nonpotable use or groundwater in confined aquifers, that has a
TDS content of 10,000 mg/L or greater (FAC 62-520.410). Disinfection is not required,
                                      4-19

-------
but all Class I well permittees must maintain the capability to disinfect (FAC 62-
600.540).

Secondary treatment requires an effluent contain not more than 20 mg/L 5-day
biochemical oxygen demand (CBOD5) and 20 mg/L total suspended solids (TSS) or that
90% of CBOD5 and TSS be removed from the wastewater influent, whichever is more
stringent At a minimum, all facilities practicing Class I deep-well injection must meet
the 20 mg/L effluent limitation. All facilities must be designed and operated to maintain
effluent pH within the range of 6.0 to 8.5, taking into account background water quality
(FAC 62-600).

4.6    Problem Formulation

Every day, hundreds of millions of gallons of treated wastewater is injected into deep-
injection wells. Subsequent migration of this wastewater, and of any dissolved or
entrained wastewater constituents, may result in exposure to receptors (including USDWs
and water-supply wells). Migration of injected wastewater and the fate and transport of
wastewater constituents from the point of injection to receptors serve an important focus
for this option-specific risk analysis.

As has been described in Chapter 3, wastewater constituents that may act as stressors to
human or ecological health can be grouped according to several broad categories (for
example, pathogenic microorganisms or VOCs). Wastewater constituents (potential
stressors) often exhibit unique physical, chemical, or biological behavior in the
subsurface. Careful selection of representative stressors is meant to account for these
differences in fate and transport. This analysis focuses on a  limited number of
representative stressors, each representing a larger category of stressor. Problem
formulation, a process involving the collection and compilation of relevant sources of
data and  information, has served to identity the best available representative stressors for
conducting this option-specific risk analysis.

The actions of large-scale physical, chemical, and biological processes in the subsurface
are key considerations for this analysis. These processes define the exposure pathways
that may be expected to bring injected wastewater (and stressors) into contact with
receptors. Transport of injected wastewater is largely a physical process, dependent on
patterns of advection or groundwater flow. Fate and transport of potential stressors,
however, is dependent upon an entire suite of processes.

Injected wastewater that is completely and permanently confined within injection zones
poses no risk to drinking water or ecological receptors; there is simply no exposure of
receptors. Wastewater that does escape confinement and moves from the intended
injection zone may pose a risk if receptors are exposed. The time of travel, which is the
time that elapses between injection (or escape from confinement) and exposure of the
receptor, is directly related to the risks that such exposure might introduce.
                                       4-20

-------
This analysis attempts to account for the complex physical phenomena that influence
whether fluid movement from the injection zone will occur. Furthermore, this analysis is
designed to investigate a number of critical questions about the nature of any such
movement:

•   What physical force components drive fluid movement (for example, buoyancy,
    pressure head)?
•   How do differences between the characteristics of native groundwater and injected
    wastewater (for example, salinity, temperature, density) affect movement?
•   What hydrogeologic units and unit properties most affect patterns of movement?
*   How might features in the sequence of confining and overlying units (for example,
    fractured rock, solution channels), if they are present, result in changes in movement?
•   Can the characteristics of injected wastewater and the properties of hydrogeologic
    units be quantified in a way that would allow them to be accurately depicted by
    modeling efforts?

This analysis produces  modeled estimates of vertical time of travel that allow
consideration of each question. However, accounting for the complexity at any single site
is a challenge, and these challenges are greatly magnified by the broad  scope of this
analysis. Data gaps and remaining uncertainties are such that this analysis requires use of
best professional judgment; these models are not field calibrated. However, this option-
specific risk analysis, while depending in part upon fate and transport modeling, does not
depend solely or entirely on this modeling. Model outputs are considered jointly with all
other sources of information, including groundwater monitoring performed in geologic
units above the injection zones.

Differences in fluid temperature and density between native and injected water affects
relative buoyancy. Injected wastewater has fluid densities that are roughly equivalent to
those of fresh water (FDEP, 1999a). This wastewater is injected at depths where the
native groundwater is saline or  hypersaline (Reese, 1994; Knochenmus and Bowman,
1998; Reese and Memburg, 1999). The comparatively lighter, less-dense wastewater
responds to a buoyancy force component that promotes vertical movement.

Another factor influencing fluid movement in subsurface geology is injection pressure. In
many settings where underground injection is practiced, increases in pressure head
(resulting from injection pressure) play a crucial role in determining the movement of
fluids. In parts of South Florida, where injection zones demonstrate a great capacity to
accept injected fluid (for example, the Boulder Zone), this force component may be less
significant This analysis accounts for the injection-pressure force component, with
attention to differences  that exist between the injection zones typical of Dade, Brevard,
and Pinellas counties.

The subsurface heterogeneity that is characteristic of South Florida introduces
complexity. Unit properties (for example, hydraulic conductivity, porosity, effective
porosity) vary from one unit to  the next, within a given unit from one site to another, and
even within a given unit at a given site. Accounting for this heterogeneity presents a
                                      4-21

-------
significant challenge in evaluating risk. In an effort to explore possibilities where
available data are limited or inconclusive, this analysis relies on an exhaustive review of
available data concerning unit properties and considers two different scenarios as it
examines uncertainty.

One example of such uncertainty regards the presence or absence of fractures, fissures,
and solution channels throughout some units in South Florida. Such conduits allow for
rapid groundwater and wastewater movement. Although seismic techniques, well-bore
imaging techniques, and other tools are available to help identify these features, such
information is not generally or widely available.

The goal of this analysis is to determine the relative risk to potential receptors. To help
evaluate this risk, this analysis uses estimated times of travel and basic information about
the behavior of representative stressors and conditions in aquifer systems to translate
initial concentrations at injection into final concentrations at receptors. An exposure
analysis attempts to account for the various processes that attenuate and dilute stressors
during the course of transport. However, as noted above, attenuation and dilution are
exceedingly difficult to model in heterogeneous environments. Furthermore, the best
available models (models that would more accurately describe three-dimensional fate and
transport) have data requirements that, in this case, cannot be met, at least for the large
study area. Necessarily, this analysis applies a number of conservative assumptions in
describing the fate of stressors, and these assumptions are intentionally designed to
overstate, rather than understate, exposure and risk.

Risk characterization is accomplished by comparing the anticipated final concentrations
at receptors with assessment endpoints. Where assessment endpoints in the form of
drinking-water-quality or other standards are not  available, a weight-of-evidence
approach is applied. The weight-of-evidence approach relies on the application of
qualified professional judgment to use and apply  findings from the scientific literature,
especially information regarding dose response or ecological thresholds.

4.7    Conceptual Model of Potential Risks for the Deep-Well Injection Option

Figure 4-5 presents a generic  conceptual model for the deep-well injection wastewater
management option. The primary source of stressors is defined as the wastewater
treatment plant from which treated effluent  is pumped to one or more deep-injection
wells. The rate of discharge varies, depending on the size and operational status of the
facility but is generally measured in millions of gallons per day.

Wastewater discharged to the subsurface (injectate) enters geologic formations within the
Floridan Aquifer System at a  preselected elevation called the injection zone. Injection
zones range from between 650 and 3,500 feet below the land surface. Injection zones are
located at an elevation where  one or more highly permeable zones have been identified
(such as the Boulder Zone in the Lower Floridan  Aquifer). Injection zones are saturated
with groundwater of salinity similar to seawater.
                                       4-22

-------
         Primary
         Source
  Waste Water Treatment
     Plant Discharge
     Potential
System Stressors
                                  Inorganic
                                  Constituents
                                 Volatile Organic
                                 Constituents
                                Synthetic Organic
                                Constituents
                                 Microbiological
                                 Constituents '
                                 Miscellandous
                                 'Constituent!
                                                     <=>
Pathways / Processes
                            Physical Processes

                               Ground Water Flow:
                                 1. Conventional Porous
                                   Media Flow
                                 2. Bulk Flow through
                                   Preferential Flow Paths
                               Dilution due to Advection
                               and Diffusion
                               Adsorption / Desorption
                               Mechanical Failure of
                               Injection System
                            Chemical Processes

                               Precipitation / Dissolution
                               Oxidation / Reduction
                               Chemical Transformation
                               Complex Formation
                             Biological Processes

                              Biogeochemical Transformation
                              Growth
                              Biodegradation
                              Microbial Inactivation
 Potential Receptors
USDW
Drinking Water Wells
 (Municipal and Private)
Irrigation Wells
Surface Water
 Phytoplankton and Zooplankton
 Submerged Aquatic Vegetation (SAV)
 Macroinvertebrates
 Fish
 Aquatic and Terrestrial Birds
 Aquatic and Terrestrial Mammals
 Reptiles and Amphibians
 Endangered Species
 Humans
                                    Potential Effects
                                   Ecological
                                    Eutrophication (excess nutrients and algal
                                      growth, low oxygen)
                                    Harmful Algal Blooms (HABs)
                                    Changes in Phytoplankton and Zooplankton
                                      Communities
                                    Toxic Effects on Aquatic and Terrestrial
                                      Species
                                    Developmental or Reproductive Changes in
                                      Aquatic or Terrestrial Organisms
                                    Reduced Growth of SAV due to Reduction
                                      in Water Clarity
                                    Food Web Effects
                                   Human Health
Figure 4-5.  Conceptual Model of Potential Risks for the Deep Well Injection Option

-------
4.7.1  Potential Stressors

Potential stressors include any dissolved or entrained wastewater constituents that may
reach receptors in sufficient concentration to cause adverse human health or ecological
effects. This may include pathogenic microorganisms, certain metals and inorganic
substances, synthetic organic compounds and VOCs, and hormonally active agents.

Appendix 1 presents data to characterize the quality of treated wastewater. Appendix
Table 1-1 presents data on a wide range of organic and inorganic wastewater constituents.
Appendix Table 1-3 and Appendix Table 1-4 present data on microbial wastewater
indicators that may be present in treated wastewater.

Several data sets included in Appendix Table 1-1 offer information to characterize
injected wastewater in South Florida:

•   Data obtained from the South Beaches Wastewater Treatment Facility in Brevard
    County describes the quality of wastewater treated to advanced wastewater treatment
    (AWT) standards.
•   Data obtained from the Albert Whitted Water Reclamation Facility in Pinellas County
    describes the quality of reclaimed water (wastewater that has received advanced
    secondary treatment).
•   Data obtained from a study sponsored by the South Florida Water Environment
    Association Utility Council (Englehardt et al., 2001). These three data sets describe
    wastewater treated by different means. In southeast Florida, where this study was
    conducted, secondary treatment is the norm for deep-well injection facilities.
•   Data obtained from the SDWWTP in Dade County describes wastewater that has
    received secondary treatment.

These data reveal trends for the quality of injected wastewater. Very few wastewater
constituents for which there are primary drinking-water standards (MCLs) have been
found to exceed standards at the point of injection. There are no metals, synthetic organic
compounds, or VOCs that appear to exceed primary drinking-water standards.

There are data to suggest that a small number of wastewater constituents may exceed
primary drinking-water standards at injection. However, these constituents do not
consistently exceed MCLs at the various facilities from which data have been collected.
Secondary drinking-water standards for TDS, color, and odor do appear to be routinely
exceeded at the point of injection.

Nitrate concentrations in excess of the MCL (10.0 mg/L) have been reported by the
following facilities: South Port St. Lucie (11.0 mg/L), Gasparilla Island (11.99 mg/L),
Seacoast Utilities (12.8 mg/L), Pahokee (14.0 mg/L), Miramar (27.0 mg/L), and North
Fort Myers (36.0 mg/L). (Of these facilities, only Seacoast Utilities in Palm Beach
County has detected any form of fluid movement from the injection zone; see Figure 4-
3). No data collected from facilities in Dade, Pinellas, or Brevard counties indicate nitrate
concentrations in excess of the MCL (Appendix Table 1-1).
                                       4-24

-------
 At the South Beaches Water Treatment Facility in Brevard County, which provides
 advanced wastewater treatment, concentrations of total trihalomethanes in excess of the
 MCL (80.0 u.g/L) have been reported. Presumably, wastewater chlorination is responsible
 for elevated concentrations (230 |^g/L) of trihalomethanes, which are byproducts
 generated during the disinfection process.

 Table 4-4 presents concentrations for those representative organic and inorganic stressors
 selected for further analysis and consideration. (All of this data may be found within
 Appendix Table 1-1.) For several  of these stressors, there is no primary drinking-water
 standard. Some are of concern primarily because of their potential to act as ecological
 stressors (for example, copper, nitrogen, orthophosphate),

 Table 4-4.    Concentrations of Representative Organic and Inorganic Stressors
Wastewater
Constituent
Arsenic
(MCL of 0.05 mg/L)
Copper
(action level of 1.0 mg/L)
Lead
(MCL of 0.015 mg/L)
Total Trihalomethanes
(MCLof80.0|ag/L)
Nitrate
(MCL of 10.0 mg/L)
Ammonia
(lifetime health advisory of
30.0 mg/L)
Total nitrogen
TKN
Orthophosphate
Chlordane
(MCLof2.0(ig/L)
Tetrachloroethylene (PCE)
(MCLof3.0|^g/L)
Di(2-Ethylhexyl)phthalate
(MCLof6.0jag/L)
South Beaches WTF1,
Brevard (Advanced)
<0.005 mg/L
N/A
N/A
230 jag/L
9.6 mg/L
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Albert Whitted WRF1,
Pinellas (Reclaimed)
O.003 mg/L
0.0086 mg/L
0.003 mg/L
6.7 |ag/L
0,28 mg/L
18.0 mg/L
18.3 mg/L
17.9 mg/L
2, 18 mg/L
<0.64 ng/L
<0.625 ng/L

-------
other nitrogenous materials (as measured by the parameters total nitrogen and TKN) may
also be of further significance to human health as sources of combined nitrogen that may
be converted to nitrate.

Pathogenic microorganisms, which are often present in treated wastewater, are another
potential human-health stressor. Appendix Tables 1-3 and 1-4 present data on a number
of wastewater indictor microorganisms present in treated and injected wastewater. Table
4-5 presents concentrations for those pathogenic microorganisms selected as
representative stressors for further analysis and consideration (see Appendix Tables 1-1,
1-3, and 1-4).

Table 4-5.    Representative Pathogenic Stressors
Pathogenic Microorganism
Total coliform, col/lOOml
(MCL of 1, 5% of samples)
Fecal coliform, cfu/lOOml
(MCL of 0)
Cryptosporidium, oocysts/100 L
(Risk-based criteriad, 5.8
oocysts/100 L)
Giardia lamblia, cysts/100 L
(Risk-based criteria , 1.4
cysts/100 L)
Enterovirus, pfu/100 L
Raw
2.2 xlO7
8xl06
N/A
N/A
N/A
Secondary Treated
0.0005 -2100"
2-
1.7xl07(397,814)b
N/A
20- 13,000 (88)e
N/A
Reclaimed
N/A
1.0
No Detect to
5.35 (0.75)
No Detect to
3.3 (0.49)
No Detect to
0.133(0.01)
Advanced
Treated
N/A
0.125 -1.15C
No Detect -
2.33
No Detect
N/A
Note: all data are extracted from complete data sets presented in Appendix 1.
" Range reflects single values and sampling means from various facilities.
b Range and mean acquired from data set for Miami-Dade, South District.
'Range reflects annual means (1999, 2001) from Cape Canaveral WWTP.
d York and Walker-Coleman, 1999; York et al., 2002.
e Rose et al., 1991; values converted from reported cysts/L.
One of these representative stressors is coliform bacteria. Levels of total coliform in
secondary treated wastewater are highly variable. Data collected by the South Florida
Utility Council indicate that secondary treated wastewater contains a mean concentration
of 394 colonies per 100 mL (Appendix Table 1-1). Table 4-5 presents a range of total
coliform levels that reflects the results of single-day sampling events from various
facilities in South Florida.

An extensive data set for the Miami-Dade South District WWTP shows fecal coliform
levels ranging over seven orders of magnitude. Levels of fecal coliform appear to be very
substantially reduced in advanced treated and reclaimed wastewater (Table 4-5).

Data to describe concentrations of some representative pathogenic stressors (for example,
rotaviruses, Cryptosporidium parvum, Giardia lamblia} are incomplete and not widely
available. Rose et al. (1991) reported that secondary-treated wastewater contains
                                        4-26

-------
concentrations ofGiardia ranging from 0.2 to 130 cysts/L (average 0.88 cysts/L). Levels
of Cryptosporidium and Giardia in advanced treated and reclaimed wastewater compare
favorably with risk-based criteria recommended by York and Walker-Coleman (1999)
and York et al. (2002).

4.7.2  Potential Exposure Pathways

When human health or ecological receptors are exposed to wastewater constituents in
sufficient concentration, these receptors may be at risk for potentially adverse health
effects. Complex processes and interactions govern how wastewater discharged to the
subsurface will move and behave. These processes and interactions define the pathways
that may expose  receptors to stressors present in treated wastewater.

Risk to receptors may arise from migration of wastewater constituents (stressors) with
groundwater flow. Such migration may occur if groundwater is allowed to move
vertically from the injection zone. Key factors influencing exposure and risk include the
distances between injection zones and receptors such as the base of the overlying USDW
and water-supply wells and times of travel to receptors. Stressors may be transported with
groundwater through porous media flow or by means of bulk flow through preferential
flow paths (for example, fractures, leaky wells).

Porous media flow, represented in this risk analysis as scenario 1, may be expected where
there are aquifers set within layers of sedimentary rock, such as is found  in South Florida.
In the case of South Florida, there is a sequence of carbonate strata, both limestone and
dolomite, within which the Upper Floridan Aquifer, middle confining unit, and Lower
Floridan Aquifer are located. Porous media flow is characterized by relatively slow
movement of fluid and by substantial dilution, especially over long distances. Dilution
occurs as a result of advection and dispersion, physical processes that occur as water
flows through interconnected pore spaces. Natural groundwater gradients, buoyancy, and
injection pressures act to carry the plume away from the injection zone.

Groundwater monitoring data indicate that bulk flow through preferential flow paths may
be occurring (and perhaps may be the dominant form of flow) in  some portions of South
Florida. This risk analysis represents bulk (channel or fracture) flow as scenario 2. Bulk
flow differs from porous media flow; the  flow is not through pore spaces in the rock
matrix, but instead through natural or man-made conduits such as solution channels,
fractures, or artificial penetrations (for example, wells with faulty construction). Bulk
flow is more rapid than porous media flow and may result in little or no dilution. In some
areas, porous media flow may be secondary to bulk flow through conduits.

4.7.3   Potential Receptors and Assessment Endpoints

Potential drinking-water receptors include USDWs overlying the injection zones, public
and private water-supply wells, and surface waters. USDWs overlying the injection zones
include the unnamed surflcial aquifers, the Biscayne Aquifer, or potable portions of the
                                      4-27

-------
Floridan Aquifer System. Some portions of the deep groundwater resource are used for
municipal water supplies; all USDWs represent a valuable resource for future use.

The surficial aquifers are important for private water supplies and for municipal supplies
in central South Florida and along the east and west coasts (Randazzo and Jones,  1997).
The Biscayne Aquifer is tapped by private wells and also supplies large public water
systems in Dade, Broward, and Palm Beach counties.

Public and private water-supply wells are typically separated both vertically and
horizontally from the injection zone and from the aquifer units directly overlying  the
injection zone. Water obtained through private wells is often used directly (without
pretreatment). Community and municipal water systems generally do pretreat
groundwater before distribution.

Utilities in South Florida make limited use of surface-water bodies as sources of drinking
water. Nevertheless, migration of wastewater constituents to such sources of drinking
water is a possibility, and therefore surface-water bodies are a potential drinking water
receptor. Perhaps more significantly, surface-water bodies  and the biological
communities they support are potential ecological receptors. Surface-water ecosystems
are particularly sensitive to some stressors present in treated wastewater (for example,
nutrients).

Federal drinking-water standards and other health-based standards serve as the analysis
endpoints for assessing risks to potential drinking-water receptors. State of Florida
surface-water quality standards (for Class I waters), and known ecological dose-response
thresholds, serve as the analysis endpoints for assessing risks to potential ecological
receptors.

4.8    Risk Analysis of the Deep-Well Injection Option

In this section, site-specific data are integrated into the conceptual model for the deep-
well injection option. Actual data on stressors, receptors, and exposure pathways were
used to examine potential risks. For representative stressors (and stressor concentrations),
information was obtained from Florida state requirements for wastewater treatment, from
actual effluent quality sampling and analyses, and from a review of the scientific
literature.

To describe the proximity and vulnerability of receptors, publicly available information
was obtained regarding the locations of public water-supply intakes.  A review of the
scientific literature provided information about the locations and physical extent of
aquifer units and USDWs in South Florida.

Information necessary to characterize possible exposure pathways was obtained from
scientific literature describing the study area's geology and aquifer unit properties, from
well-bore log reports and other well completion reports, and from previous studies and
investigations that have  examined deep-well  injection in South Florida.
                                       4-28

-------
This analysis incorporates a two-dimensional analytical description (model) of the fate
and transport of injected wastewater and wastewater constituents. The analytical
description is accompanied by uncertainty analyses that examine potential variations in
time of travel. This analysis of deep-well injection also makes use of groundwater
monitoring performed above some zones of injection. Monitoring information is
incorporated as a means of analyzing the model outputs and of more fully exploring the
various mechanisms that may allow for fluid and stressor movements in the subsurface.

Dade, Pinellas, and Brevard counties serve as three areas of focus for this risk analysis.
Facilities with suspected or confirmed fluid movement are sited within each of these
counties. However, these counties also present unique geologic environments and
differences in injection system operation that may have a substantial bearing on risk.

This analysis examines, as broadly as possible, the fate and transport of injected
wastewater within the South Florida study area. Data gaps and remaining uncertainties
are significant, and this risk analysis provides only a generic description of the risks that
may be associated with this wastewater management option. Findings are applicable, in a
general way, to these counties and the region as a whole. Findings are not applicable, in a
very specific way, to particular sites or facilities.

4.8.1   Application of the Analytical Transport Model

This analysis employs an analytical model that considers two different scenarios for fluid
flow and migration of wastewater in the subsurface: conventional porous media flow and
bulk flow through preferential flow paths. These scenarios represent two end-members of
constraint upon fluid migration in the subsurface. Subject to data and model limitations,
these scenarios provide estimates of what are likely to be the fastest and slowest rates of
fluid flow and migration. Although these are analyzed and presented as separate
scenarios, it is possible (perhaps even likely) that both types of flow occur simultaneously
in some aquifer units (for example, fractures within, leading to, or leading from porous
media).

Conventional porous media flow is a scenario where fluid flows through fine,
interconnected pore spaces. This scenario is modeled under the assumption that aquifer
units and geologic media do not have fractures or other major conduits that would permit
rapid channel flow. Primary values of hydraulic conductivity and porosity are applied in
modeling flow through porous media. (Tables 4-1,  4-2,  and 4-3, presented earlier in this
same chapter, report specific values.) Figure 4-6  illustrates movement of injectate where
flow through porous media is the primary transport mechanism. Natural groundwater
gradients, buoyancy, and injection pressures act to  carry the plume away from the
injection zone.

Bulk flow through preferential flow paths (channel or fracture flow) is a scenario where
fluid flows through naturally occurring or man-made conduits. Naturally occurring
conduits include fractures,  solution channels, and fissures. Man-made conduits might
include injection wells with faulty construction, monitoring wells with faulty
                                       4-29

-------
construction, abandoned wells, or fractures created because of well drilling or injection.
Figure 4-7 illustrates the flow of injectate where bulk flow is the primary mechanism of
plume migration. It is important to note that preferential flow pathways may result from
the presence of naturally occurring solution channels or fractures in geologic strata or
from mechanical problems associated with wells.

There are data to support the existence of naturally occurring features that could promote
or allow for bulk flow. The Boulder Zone, a complex fracture zone with high hydraulic
conductivity, is known in some locations to feature vertical fissures or solution channels.
At the SDWWTP, small fractures have been detected by gamma ray and other surveys at
depths ranging from 2,465 to 2,535 feet (CH2M Hill, 1977). This zone was originally
thought to be part of the middle confining unit, but was later reassigned to the Lower
Floridan Aquifer. Fractures appear to exist over a 70-foot interval within the confining
unit and, if interconnected, could serve as preferential flow paths for injected wastewater.

Duerr (1995) and McNeill (2000) provide evidence to support the conclusion that natural
fractures, pugs, or cavities may be common in South Florida. Duerr (1995) reports the
findings from a study conducted by the U.S. Geological Survey in  1990. This study
observed fractures of the Floridan Aquifer in at least three counties (Broward, Indian
River, and Manatee counties). In contrast to these findings, other studies have found that
groundwater movement in many aquifer units is consistent with flow through porous
media, with little or no channel flow. Meyer (1989), Duncan  et al. (1994), and Maliva
and Walker (1998) have reported similar findings for groundwater flow in the Upper
Oldsmar Formation (part of the middle confining unit).

This analysis applies a continuum approach to modeling groundwater flow through
fractured rock (Freeze and Cherry, 1979). This approach reassigns values of hydraulic
conductivity and porosity to represent fractured geologic media. Best professional
judgment  has been exercised in selecting and reassigning  secondary porosities and
hydraulic  conductivities, based on an evaluation of the primary literature (Appendix 2).
Many of the values employed for this analysis are reported in McNeil (2000). These
values are consistent with what has been  reported by other sources from the literature.
Tables 4-1, 4-2, and 4-3 (presented earlier in this same chapter) report specific values
applied in modeling transport for Dade, Pinellas, and Brevard counties, respectively.

For each scenario, the transport model  estimates vertical times of travel to two receptors.
The first of these is the base of the nearest overlying USDW. The vertical distance
separating an injection zone from the nearest USDW is  an important input to the model.
These distances are similar for Dade and  Brevard counties (roughly 1,000 ft.), but
substantially shorter for Pinellas County.

The second receptor is defined as the depth of current water supplies. The model
estimates vertical times of travel to a depth (in each county) that is typical of public
water-supply intakes.
                                       4-30

-------
 This analysis estimates the extent of horizontal migration as a function of estimated
 vertical times of travel and hydrogeofogic data (such as horizontal hydraulic conductivity
 and porosity, hydraulic gradients). This information provides for useful comparisons with
 the known real-world locations of public water-supply wells in Dade, Pinellas, and
 Brevard counties.

 This analysis must contend with significant sources of uncertainty, especially regarding
 how key aquifer unit properties (for example, hydraulic conductivity, porosity) may vary
 throughout the study area. For each scenario, an uncertainty analysis examines how times
 of travel are influenced by the most important governing hydrogeologic parameters. The
 role and influence of primary hydraulic conductivity  is analyzed for the conventional
 porous media scenario. The influence of secondary porosity is analyzed for the scenario
 that considers transport through preferential flow paths.

 4.8.2  Vertical Times of Travel and Horizontal Migration

 Injected wastewater moves both vertically and horizontally away from the point of
 injection. The rate of travel is influenced by properties of the aquifer, by the direction of
 prevailing groundwater flow, and by at least two separate force components (pressure
 head resulting from injection and pressure head resulting from buoyancy).

 Groundwater flow equations may be used to estimate vertical times of travel through
 hydrologic units (Appendix 4). These equations take  into account unit thickness, porosity,
 and vertical hydraulic conductivity. Tables 4-1  through 4-3 report representative values
 for these model parameters, specific to Dade, Pinellas, and Brevard counties. Mean
 (weighted) values are based on a statistical analysis of data reported in the scientific
 literature. A description of the statistical methods and literature-derived data are provided
 in Appendices 2 and 3.

 Total pressure head, another input to the groundwater flow equations, is a composite of
 two force components. Pressure head from injection is the  force component that results
 from the injection of treated wastewater and displacement  of native groundwater.
 Pressure in the injection zone (and resistance to fluid emplacement) builds as a function
 of unit transmissivity and the injection rate (Appendix 4).

 Pressure head from buoyancy results from differences in density between the injectate
 and native groundwater. Injected wastewater exhibits salinity and density comparable to
 freshwater  (1.00 grams per milliliter), whereas the native groundwater has salinity and
 density comparable to seawater (1.025 grams per milliliter). The comparatively lighter,
 less dense wastewater responds to a buoyancy force component that promotes vertical
movement (Appendix 4). A similar effect might result from temperature gradients. The
temperature of injected wastewater is estimated to be 80° Fahrenheit, whereas native
groundwater has a temperature far closer to 60° Fahrenheit. Warmer, less-dense injectate
will tend to rise upward until it reaches fluids of a similar density (Appendix 4).
                                       4-35

-------
For Pinellas County, both force components are considered when estimating vertical
times of travel to the overlying USDW and the depth of current water supplies. For Dade
and Brevard counties, where substantial evidence indicates pressure from injection is
negligible, only the effects of buoyancy are considered.

Horizontal migration of injected wastewater is assessed as the distance traveled laterally
within each unit as function of estimated vertical time of travel. A set of groundwater
flow equations (Appendix 5) estimates horizontal travel distance, taking into account
porosity, horizontal conductivity, and hydraulic gradient.

4.8.2.1 Governing Assumptions for the Transport Model

The following are the governing assumptions for the transport model:

   •   Deep-well injection facilities are modeled as single-point sources of discharge.
       Volumes and rates of injection typical  of whole facilities are modeled as single-
       point discharges within each injection zone. (Note that this is an abstraction; most
       facilities have more than one well.) This represents a conservative assumption
       about risk assessment, since it would tend to result in greater pressure heads from
       injection and shorter estimated times of travel.
   •   Pressure head from injection is estimated for the injection zone only. Pressure is
       attenuated as fluids pass through overlying units with differing hydraulic
       properties. Overlying units with lower relative hydraulic conductivity dampen and
       distribute pressure.
   •   In Dade and Brevard counties, pressure head from injection is regarded as
       negligible. The Boulder Zone is highly karstified with solution channels and wide
       fractures that do not constrain the flow of injected effluent; therefore, only
       negligible pressure buildup is likely to occur (Haberfeld, 1991).
   •   Estimated total pressure heads  do not account for natural gradients that may occur
       at some sites.
   •   Changes in native groundwater temperature and salinity are assumed to be
       gradual.
   •   Calculations of pressure head because  of buoyancy force assume no mixing of
       injected water and native fluid, dilution, or dispersion. This is a conservative
       approach; this assumption leads to higher buoyancy heads and shorter times of
       travel.

4.8.2.2 Vertical Time-of-Travel Results and Discussion

In Dade and Brevard counties, injection occurs within the Boulder Zone. Flow through
the Boulder Zone is extremely rapid because of cavernous pores, fractures, and widened
joints. Accordingly, pressure heads from injection are regarded as negligible in these
counties (Table 4-6). In Pinellas County, injection occurs within the Upper Floridan
Aquifer, a unit far less conductive than the Boulder Zone. As a means of comparison,
consider the representative values for hydraulic conductivity of the UFA , (Pinellas
County) and the Boulder Zone (Dade and Brevard counties); see tables 4-1, 4-2, and 4-3.
                                       4-36

-------
Table 4-6.    Pressure Head from Buoyancy and Injection (Scenario 1)
Dade County
Injection rate = 1 12.5 mgd '
Pinellas County
Injection rate = 7 mgd
Brevard County
Injection rate = 5 million mgd
Components
Buoyancy
Injection
Total Head z
Components
Buoyancy
Injection
Total Head 2
Components
Buoyancy
Injection
Total Head 2
To Receptor Well
73ft
Oft
73ft
To Receptor Well
18ft
533ft
551ft
To Receptor Well
Illft
Oft
Illft
To USDW
68ft
Oft
68ft
To USDW
16ft
533ft
549ft
To USDW
92ft
Oft
92ft
Note: Scenario 1 assumes conventional porous media flow.
1 Mgd = million gallons per day.
2 Total pressure heads do not account for natural gradients that may be present at some sites.
In Pinellas County, pressure head from injection is a significant driving force, far more
important than pressure head from buoyancy (Table 4-6). Pressure head from injection
was evident during the course of injection-well testing performed in Pinellas County.
Water levels in nearby monitoring wells increased in elevation during tests (CH2M Hill,
2001), indicating pressure head buildup from injection.

For Pinellas County, where pressure head from injection is significant, total pressure head
is estimated a  second time under the assumptions of scenario 2. This scenario examines
behavior under an assumption that preferential flow paths (cracks, fissures, and so forth)
exist. Applying representative secondary porosities  and hydraulic conductivities, the
estimated pressure head from injection is substantially reduced when compared to the
estimate under scenario 1 (Table 4-7).

Table 4-7.    Pressure Head from Buoyancy and Injection (Scenario 2)
Pinellas County
Injection rate = 7 mgd
Components
Buoyancy
Injection
Total Head 2
To Receptor Well
18ft
122ft
139ft
To USDW
16ft
122ft
137ft
Note: Scenario 2 assumes bulk flow through preferential flow paths.
2 Total pressure head does not account for natural gradients mat may be present at some sites.
Estimates of vertical time of travel under each scenario are presented in Table 4-8 for
Dade, Pinellas, and Brevard counties. The full set of model inputs and outputs are
included as part of Appendix 4. Table 4-8 also reports vertical distances (in feet)
separating injection zones from the base of overlying USDWs and hypothetical water-
supply wells. These distances and estimated times of travel reflect average conditions in
                                        4-37

-------
each county as a whole. Times of travel may vary across the injection facilities operating
within each county.

Table 4-8.    Times of Travel to USDWs and Hypothetical Receptor Wells
Location
Vertical Distance
from Point of
Injection (ft)
Estimated Time of
Travel
(scenario 1)'
Estimated Time
of Travel
(scenario 2)2
Dade County
TobaseofUSDW
To receptor well
(100 ft below ground surface)
1,500
2,900
421 years
1,1 88 years
14 years
30 years
Pin el las County
TobaseofUSDW
To receptor well
(30 ft below ground surface)
570
1,220
2 years
23 years
170 days
6 years
Brevard County
TobaseofUSDW
To receptor well
(100 ft below ground surface)
1,254
2,650
342 years
1,118 years
86 years
136 years
Note: Travel time through each hydrologic unit is presented in Appendix Tables 4-1 through 4-4.
1 Scenario 1 assumes conventional flow through porous media.
2 Scenario 2 assumes bulk flow through preferential flow paths.
Under either scenario, Pinellas County has the shortest estimated times of travel to each
receptor. Injection zones in Pinellas County are at significantly shallower depths relative
to injection zones in Dade and Brevard counties; injectate has shorter distances to travel
before reaching receptors. Hydrologic units in Pinellas County are also, in general, more
permeable than in Dade and Brevard counties. In Dade and Brevard counties, there are
confining units that serve to slow movement of fluid between injection zones and
potential receptors (such as USDWs and hypothetical wells). The intermediate confining
unit is completely absent in Pinellas County. Formations associated with the intermediate
confining unit serve to slow transport to hypothetical receptor wells.

When bulk flow through preferential flow paths is assumed (scenario 2), estimated times
of travel are significantly reduced in all three counties. In Dade and Brevard counties,
times of travel are reduced by more than an order of magnitude (Table 4-8), from
thousands of years to hundreds of years or less (scenario 1).

Dade County, exhibits the longest estimated times of travel: 421 years to the base of the
USDW, 1,188 years to the hypothetical receptor well (under scenario 1). Since pressure
head from injection is not an important factor in either Dade or Brevard County,
differences in the rate of injection cannot account for the comparatively longer times of
travel in Dade County. The comparatively longer estimated times of travel in Dade
County are most attributable to differences in unit hydraulic properties.
                                        4-38

-------
 Scenario 2 applies a set of very conservative assumptions regarding unit hydraulic
 properties and bulk flow. At no site where data have been collected is there sufficient
 evidence to conclude that bulk flow through preferential flow paths is characteristic of all
 hydrologic units. However, based on recent detection of treated effluent at certain
 wastewater treatment sites, bulk flow could contribute to the early detection of treated
 effluent. Accordingly, given the data and information that inform the present analysis,
 estimates obtained under scenario 2 are thought to represent the shortest possible times of
 travel.

 Conservative assumptions are also implicit in the estimated times of travel to hypothetical
 receptor wells. These times of travel should be considered in light of the horizontal
 separation known to exist between injection wells and actual receptor wells.

 4.8.2.3 Horizontal Migration

 The ideal model, or set of models, would achieve multidimensional analysis. The data
 required to perform a multidimensional analysis of transport, particularly within
 heterogeneous environments, can be extensive. This requires a level of data specificity
 and field model calibration that is beyond the broad scales intended for this risk analysis.
 In the context of this regional-scale analysis, these data requirements proved prohibitive.

 Table 4-9 presents estimates of horizontal travel distance for effluent in groundwater
 beneath the facilities in each county. These estimates take into account the estimated
 vertical times of travel and representative values for unit porosity, horizontal
 conductivity, and hydraulic gradient. Additional details and model inputs and outputs are
 described in Appendix 5.

 Table 4-9.    Estimated Horizontal Travel Distances
Scenario
Scenario 1 '
Scenario 22
Bade
Time
(years)
1,188
30
Distance
(miles)
16
1.6
Pinellas
Time
(years)
23
6
Distance
(miles)
1.2
0.6
Brevard
Time
(years)
1,118
136
Distance
(miles)
1.5
0.1
Note: Horizontal travel distance through each hydrologic unit is presented in Appendix 5.
1 Scenario 1 assumes conventional porous media flow.
2 Scenario 2 assumes bulk flow through preferential flow paths.
Horizontal travel distance is described analytically as a simple function of vertical time of
travel. Accordingly, scenario 1 (conventional porous media flow) results in more
substantial horizontal travel distances than does scenario 2 (bulk flow through
preferential flow paths).

Assuming conventional porous media flow, horizontal travel distance was estimated at 16
miles for Dade County (Table 4-9). All other estimates (under either scenario) are less
than 2 miles. The comparatively large horizontal travel distance estimated for Dade
                                        4-39

-------
County is most attributable to horizontal migration that occurs within the intermediate
confining unit (Appendix 5). This retards vertical movement, but groundwater travel
through this unit takes the greatest time.

Under a given set of hydraulic conditions, horizontal travel distance is a simple function
of vertical time of travel. When travel distances are estimated under differing conditions,
the significance of hydraulic gradient becomes apparent. Horizontal travel distances
estimated for Pinellas County are comparable to those estimated for Brevard County,
despite the great discrepancies in time of travel. This may be attributed to the fact that
horizontal hydraulic gradient in the injection zone is estimated at 0.05 for Pinellas County
and just 0.001 in Brevard County (Appendix Tables 5-1 and 5-2).

Estimates of horizontal travel through the Boulder Zone are relatively insignificant, when
compared to total horizontal travel distances. The model predicts that injected wastewater
moves quickly from the Boulder Zones, but primarily in a vertical direction. In Dade
County and Brevard County, the estimated vertical times of travel through the Boulder
Zone are 16 and  6 days, respectively. This allows for very limited horizontal transport
within the Boulder Zone in the direction of prevailing groundwater flow (Appendix
Tables 5-1 and 5-2). A numerical model used to simulate injection in Southwest Florida
(Hutchinson and Trommer,  1992; Hutchinson et al., 1993) has described similarly short
horizontal migration distances in the Boulder Zone.

4.8.2.4 Transport Model Limitations

As indicated in previous sections (especially sections 4.6 and 4.8.1),  the analytical
models applied in assessing vertical and horizontal transport are not ideal. It is critical,
therefore, to recognize and acknowledge model limitations that may  influence how risk is
evaluated. These transport models  are subject to two significant limitations:

   •   The presence and extent of preferential flow paths, or alternative wastewater
       migration pathways, is not adequately known. The significance of these pathways
       to both wastewater transport and risk can only be estimated.
   •   Substantial data gaps exist. There are limited data and information that may be
       used to develop and  assign accurate values for some model input parameters. At
       present, this is an unavoidable source of remaining uncertainty.

Numerous studies and investigations offer evidence that indicate the  presence of
alternative wastewater-migration pathways, which are preferential flow paths that permit
bulk flow of injected wastewater (CH2M Hill, 2001; McNeill, 2000; McKinley, 2000;
MDWSAD, 1991; CH2M Hill, 1981; Miami-Dade Water and Sewer Authority, 1977;
BC&E and CH2M Hill, 1977). Taken as a whole, these reports indicate that potential
pathways may exist and that these pathways may short-circuit flow paths associated with
conventional flow through porous media.

This analysis does not describe in a quantitative way the flow dynamics of particular
types of alternative pathways (for example, fractured confining zones or wells with failed
                                       4-40

-------
mechanical integrity). Furthermore, it is beyond the scope of this analysis to determine
what pathways may be responsible for bulk flows at particular sites or to evaluate the
risks that may be associated with particular types of alternative pathways. For the
purposes of this risk assessment, analysis of flow and transport through preferential flow
paths (scenario 2) fairly and adequately describes these alternative pathways.

The permit process offers better opportunities to evaluate the suitability of specific well
sites and injection zones. The permit process is also designed to anticipate and prevent
potential problems related to well operation (and adverse impacts resulting from
injection).  State and federal underground injection control authorities are charged with
ensuring that all necessary and appropriate measures are taken (that is, permit
requirements established) to prevent endangerment of USDWs and adverse  impacts to
public health.

4.8.2.5 Uncertainty Analysis

Model accuracy is constrained by the completeness and accuracy of data used to assign
values for model input parameters.  This analysis employs values that are representative
of each unit overlying injection zones in Dade, Pinellas, and Brevard counties. These
values are based on a statistical analysis of data reported in the scientific literature (see
Appendices 2 and 3). Inherently, however, there are site-specific variations in aquifer unit
properties across each county and across the whole of the South Florida study area. As
such, this transport analysis must contend with uncertainty, and the accuracy of estimated
times of travel is somewhat constrained.

Uncertainty analyses may be conducted as a means of evaluating the range of expected
times of travel under each scenario. These analyses focus on how times of travel are
influenced  by governing hydrogeologic parameters. Most important to this model are the
assigned  vertical hydraulic conductivity and porosity values. More specifically, the
values assigned to those units that most significantly influence vertical time of travel (for
example, the middle confining unit in Dade and Brevard counties and formations
associated with the intermediate confining unit in Pinellas County).

Times of travel to hypothetical receptor wells, under the assumption of porous media
flow (scenario 1), are estimated as employing a range of values for vertical hydraulic
conductivity.  Times of travel under the assumption of bulk flow through preferential flow
paths (scenario 2) are estimated as employing a range of values for secondary porosity.

Table 4-10 reports results of the uncertainty analyses conducted for each scenario and
county. Complete information to describe these analyses and the computed upper and
lower bounds is included in Appendix 6. Appendix 6 also offers graphical representations
of the uncertainty analyses for Dade, Pinellas, and Brevard counties (Appendix Figures
6-1, 6-2, and 6-3, respectively).
                                       4-41

-------
Table 4-10.   Range of Travel Times to Hypothetical Receptor Wells
Effect of Hydraulic Conductivity (Kv) on Vertical Travel Times, in Years (scenario I)1
Location
Dade County
Pinellas County
Brevard County
Lower Bound

-------
For each county, these analyses estimate final concentrations of representative stressors
anticipated to reach the base of the nearest overlying USDW and hypothetical water-
supply well. Analyses are conducted under each of the scenarios developed in previous
sections (conventional porous media flow and bulk flow through preferential flow paths)
and apply mean times of travel estimated for each county.

These analyses attempt to account for the various processes that may attenuate and dilute
stressors during the course of transport. Natural attenuation involves physical, chemical,
and biological processes that result in reducing the mass, toxicity, mobility, volume, or
concentration of contaminants in soil or groundwater (US EPA, 1999, cited in Suthersan,
2002). Processes that may contribute to stressor attenuation include biodegradation,
hydrolysis, sorption, volatilization, radioactive decay, chemical or biological
stabilization, and transformation.

Sorption processes cause stressors to adhere to geologic materials; this has the effect of
slowing down migration and may increase the vertical time of travel for some
representative stressors. Degradation is a biological process whereby organic materials
are broken down under aerobic or anaerobic conditions. Hydrolysis occurs when organic
or inorganic solutes react with water and transform to less mobile forms.

Modeling attenuation and dilution on these scales (particularly under heterogeneous
conditions and with very limited data sets) is exceedingly difficult. These analyses apply
a number of conservative assumptions that would tend to overstate,  rather than
understate, exposure and risk. Most importantly, these analyses only very crudely account
for dilution as a result of advective transport and dispersion. Fluids that reach potential
receptors because of injection activities (that is, waste water and displaced native
groundwater) may be more substantially diluted than predicted by these analyses.

Finally, because of model limitations and the general lack of needed data and
information, quantitative fate and transport analyses are not provided for any of the
pathogenic stressors. Rather, a weight-of-evidence approach applies information from the
scientific literature to assess the likely behavior of these microorganisms and to
characterize the risk posed to potential receptors.

4.8.3.1 Application of the Stressor Fate and Transport Model

The following stressors were  selected for fate and transport analysis: ammonia, arsenic,
chlordane, chloroform (measured as total trihalomethanes), di(2-ethylhexyl) phthalate
(DEHP), nitrate, and tetrachloroethylene (PCE). Initial concentrations (concentrations at
the point of injection) were assigned based on values reported in Appendix Table 1-1;
these are summarized in Table 4-11.
                                       4-43

-------
Table 4-11.   Concentrations of Representative Stressors at USDWs and
              Hypothetical Wells
Bade County
Ammonia (mg/L)
Arsenic (mg/L)
Chlordane (u,g/L)
DEHP (ng/L)
Nitrate (mg/L)
PCE(ng/L)
Trihalomethanes,
total (ug/L)
C,at
Injection
8.75 c
0.01
0.01 d
5.00 d
3.82 c
4.66
61.58
Cf at USDW
(Scenario 1)°
8.75
0.01
0.000
0.000
3.82
0.000
0.000
Cf at Well
(Scenario 1)"
8.75
0.01
0.000
0.000
3.82
0.000
0.000
Cr at USDW
(Scenario 2)b
8.75
0.01
0.000
0.000
3.82
0.02
7.24
Cf at Well
(Scenario 2)b
8.75
0.01
0.000
0.000
3.82
0.010
5.32
MCL
NA
0.05
2.00
6.00
10.00
5.00
80.00
Pinellas County
Ammonia (mg/L)
Arsenic (mg/L)
Chlordane (ug/L)
DEHP (us/L)
Nitrate (mg/L)
PCE(ug/L)
Trihalomethanes,
total (fig/L)
18.00
0.003 d
0.64 d
1.25d
0.28
0.63
6.70
18.00
0.003
0.50
0.22
0.28
0.27
4.90
18.00
0.003
0.21
0.00
0.28
0.02
1.64
18.00
0.003
0.61
0.86
0.28
0.52
6.27
18.00
0.003
0.50
0.22
0.28
0.27
4.90
NA
0.05
2.00
6.00
10.00
5.00
80.00
Brevard County
Ammonia (mg/L)
Arsenic (mg/L)
Chlordane (ixg/L)
DEHP (ug/L)
Nitrate (mg/L)
PCE(ug/L)
Trihalomethanes,
total (ug/L)
8.75 c
0.005 d
0.01 d
5.00 d
9.60
1.00d
230
8.75
0.005
0.000
0.000
9.60
0.000
0.000
8.75
0.005
0.000
0.000
9.60
0.000
0.000
8.75
0.005
0.000
0.000
9.60
0.000
0.000
8.75
0.005
0.000
0.000
9.60
0.000
0.000
NA
0.05
2.00
6.00
10.00
5.00
80.00
a Scenario 1 assumes conventional porous media flow.
 Scenario 2 assumes bulk flow through preferential flow paths.
c Limited site-specific data. Concentrations in secondary treated wastewater from various facilities in southeast Florida;
    reported by Englehardt et al., 2001.
a Detection limit.
Appendix 7 describes the fate and transport model used to estimate final stressor
concentrations (concentrations at receptors). Times of travel specific to each
representative stressor (excluding pathogenic microorganisms) are obtained by modifying
the previously determined times of travel (section 4.8.2.2.) with retardation coefficients.
(The fate and transport of pathogenic microorganisms are examined under a separate
section, section 4.8.3.3.)

Retardation coefficients developed from referenced chemical sorption coefficients
(Appendix 7) account for sorption processes that act to slow the movement of solutes as
fluids move through hydrologic units. Ultimately, sorption processes produce differences
between the velocity of groundwater flow and the velocities of dissolved or entrained
stressors.
                                         4-44

-------
 Biodegradation and hydrolysis are two processes that act to reduce the mass (or
 concentration) of organic stressors over the course of transport. Rates of biological
 degradation and hydrolysis may be expressed as a half-life for each organic compound.
 Half-life is the time required for a concentration of reactant to decrease to half of its
 initial concentration.

 Time of travel directly affects how much attenuation will occur as a result of these
 processes prior to stressors reaching receptors. A first-order decay model is used to obtain
 final stressor concentrations that account for biodegradation and hydrolysis (Appendix 7).
 This model employs stressor-specific times of travel and published half-life values for
 organic stressors.

 This model assumes conservative behavior for inorganic stressors. Final concentrations
 of inorganic stressors (for example, ammonia, arsenic, nitrate) are influenced by sorption
 processes but not by degradation, hydrolysis, or transformation. While these assumptions
 may be questioned, particularly in the case of ammonia, there is insufficient information
 with which to model the types of transformations that may occur (for example, oxidation
 of ammonia to other nitrogenous forms). Nevertheless, these assumptions do result in
 model outcomes that are conservative for exposure analysis and risk assessment.
4.8.3.2 Final Concentrations of Chemical Stressors

Four tables included in Appendix 7 (Appendix Tables 7-1 through 7-4) report, in their
entirety, the model inputs and outputs. Table 4-11 provides a summary of the estimated
final stressor concentrations that the model predicts may reach USDWs and hypothetical
water supply wells under each scenario.

Under the assumptions of scenario 1 (conventional porous media flow) and scenario 2
(bulk flow through preferential flow paths), estimated final stressor concentrations for
both receptors and in all three counties (Dade, Pinellas, and Brevard), are below primary
drinking-water standards. This is despite the faster estimated times of travel that prevail
where bulk flow through cracks, dissolution channels, and other conduits is assumed.
Ammonia, for which there is no maximum contaminant level (only a Lifetime Health
Advisory level), does not appear to exceed health-based criteria at either receptor, under
any of the model conditions.

Time of travel plays a crucial role in determining the stressor concentrations to which
potential receptors may be exposed. The clearest illustration of this role may be seen in
the organic stressor  concentrations estimated for receptors in Pinellas County. Section
4.8.2.2 demonstrates how bulk flow through preferential flow paths (scenario 2) may
result in substantially shorter times of travel. Under the assumptions of scenario 2,
organic stressors reach the base of the overlying USDW in Pinellas County only
minimally reduced from the initial concentrations at injection (Table 4-11). In Dade and
Brevard counties, where the times of travel are more than an order of magnitude greater
than in Pinellas County, organic stressors are substantially reduced before reaching
                                       4-45

-------
USDWs. Under the assumptions of scenario 1, organic stressors in Pinellas County are
more substantially reduced from attenuation that occurs prior to fluids reaching the base
of the USD W.

Where this model is capable of describing attenuation processes (for example, for the
organic stressors), results show very clearly the significance of time of travel.
Furthermore, these results illustrate how the presence (or absence) of preferential flow
paths can substantially influence the types of exposures that may be expected to occur.
As was expected for the organic stressors, estimated final concentrations obtained under
scenario 2 (bulk flow through preferential flow paths) are greater than the estimates
obtained under scenario 1 (conventional porous media flow) for both receptors and in all
three counties (Table 4-11).

There are important differences in the way that the various organic stressors behave in the
subsurface. Variations in sorption characteristics and half-life translate into relatively
more or less conservative behavior for individual organic stressors. Chlordane and DEHP
have comparatively higher sorption and distribution coefficients that result in higher
retardation coefficients and longer stressor-specific times of travel (Appendix Tables 7-1
through 7-4). Chlordane, and to a lesser extent trihalomethanes, have comparatively long
half-lives and smaller decay coefficients; this has the effect of lessening (in a
comparative sense) the amount of attenuation that occurs over time.

Among the organic wastewater constituents modeled as representative stressors, DEHP
represents a relatively slow-moving compound and one that can be expected to
significantly and quickly attenuate. Trihalomethanes represent a relatively fast-moving
compound and one that can be expected to attenuate more slowly  or incompletely.

Trihalomethanes, though present at varying concentrations in injected wastewater, do not
under any of the model conditions pose a significant threat of violating drinking-water
standards. For Pinellas County, where times of travel are comparatively short, this threat
is mitigated  by the fact that trihalomethanes appear to be present at only very low
concentrations in the injected wastewater. For Brevard County, where some data indicate
high trihalomethane concentrations at injection, this threat is mitigated by comparatively
long travel times.  Trihalomethanes injected at concentrations greater than twice the MCL
are expected to reach receptors in Brevard County at below detection limits under either
scenario.

This model assumes conservative behavior for the inorganic representative stressors
(ammonia, arsenic, and nitrate). It is assumed that final concentrations of ammonia,
arsenic, and nitrate will not be  influenced by degradation, hydrolysis, or transformation
processes. Accordingly, Table  4-11 reports final concentrations at each of the receptors
(and under each scenario) that are identical to the concentrations at injection. These
assumptions are conservative, as regards exposure analysis and risk assessment; they will
tend to overestimate exposure and risk.
                                       4-46

-------
Under some geochemical conditions, metals such as arsenic may become immobilized in
the aquifer matrix. Model estimates of the time of travel for arsenic, which does exhibit
fairly strong sorption characteristics, are long by comparison to several of the other
representative stressors. Only chlordane and DEHP have estimated stressor-specific times
of travel that consistently exceed those estimated for arsenic (Appendix Tables 7-1
through 7-4). However, even under the conservative set of assumptions applied in
examining the fate of arsenic, there appears to be no threat of drinking-water violations
under any of the model conditions. Arsenic is often present in injected wastewater at very
low concentrations and frequently at concentrations that cannot be detected.

Ammonia and nitrate both move far more readily with groundwater flow. It is unlikely
that for either of these stressors that time of travel is significantly increased because of
sorption processes (Appendix Tables 7-1 through 7-4).  While there are processes that
might cause attenuation of ammonia or nitrate in the subsurface, these processes are
microbially mediated and very difficult  to model with the present data limitations.

Under oxic conditions, dissolved ammonia (or ammonium) may be oxidized to nitrite and
nitrate, as a result of a process called nitrification (Fenchel and Blackburn,  1979;
Blackburn, 1983). Rates of growth for nitrifying bacteria are typically increased at
temperatures between 30° and 35° Celsius; poor growth occurs at temperatures below 5
°Celsius (Buswell et al., 1954; Deppe and Engel, 1960,  summarized in Fenchel, 1983).
Nitrifying bacteria can survive under anoxic conditions but experience high rates of
mortality wherever hydrogen sulfide is produced by anaerobic sulfate-reducing bacteria
(reviewed in Blackburn, 1983).

These findings from the literature imply that the conservative behavior assumed for
ammonia may be more defensible with respect to estimated concentrations  at the base of
the USDW, than for estimated concentrations at hypothetical water-supply  wells.
Portions of aquifers lying below and including the base of the USDW are most certainly
anoxic, allowing for comparatively less  nitrification (conversion of ammonia to other
nitrogenous forms). However, water-supply wells penetrate to shallow depths in most
parts of South Florida. At these depths, oxic conditions may prevail and may  lead to
increased rates of nitrification and attenuation of ammonia.

Nitrate may be subject to microbial denitrification (conversion to nitrous oxide and
ammonia) and to other forms biological uptake or conversion. The U.S. Geological
Survey has reported significant rates of denitrification in shallow groundwater beneath
Florida citrus groves (USGS, 2000). Denitrification in shallow groundwater has also been
reported by a study of septic  systems in  areas bordering the Indian River Lagoon
(Horsley & Witten, 2000). These findings suggest that completely conservative behavior
of nitrate, at least in shallower aquifers,  is unlikely.

4.8.3.3 Fate and Transport  of Pathogenic Microorganisms

Assessing the potential human health risks from microbial pathogens in injected treated
wastewater depends to a large extent on  evaluating the fate and transport of pathogenic
                                       4-47

-------
microorganisms. A crucial step in risk assessment is determining whether pathogens can
be transported in an infective form to drinking water receptors and to human receptors.
Thus, there are four risk questions to address:

    •      Can pathogenic microorganisms be transported in groundwater through
          geologic media?
    •      Can pathogenic microorganisms survive and remain infective after a long
          period of time traveling in groundwater?
    •      What are regulatory standards or recommendations?
    •      What are infective doses and how do actual or predicted concentrations of
          microorganisms in effluent at the drinking-water receptor compare with
          infective doses and standards?

Assessment endpoints used in this microbial risk assessment include a 1 in 10,000 (1 x
10"4) risk threshold used by the DEP and regulatory standards, where such standards exist
(FDEP, 1998). If regulatory standards do not exist, then other human health advisory or
illness doses or other state or federal recommendations are used.

Valuable information for this analysis of microbial risks was provided by the DEP, which
published a risk assessment of reuse and reclaimed water based on a number of other
Florida studies and its own risk assessment (FDEP, 1998). Although the objective of that
study was evaluation of the risks of reclaimed water, the approaches and assumptions
used are applicable for this study of deep-well injection. These are listed in Table 4-12.

Table 4-12.   Assumptions Used for Florida DEP's Human Health Risk Assessment
              for Reuse
Parameter
Daily human ingestion rate
Recreational contact dose
Contact from residential irrigation (worst-case single ingestion)
Residential irrigation, routine exposure
Consumption of edible crops irrigated with water
Irrigation of public-access areas such as golf courses, parks
Exposure to aerosols
Assumption
2L/day
100 mL
100 mL
ImL
10 mL
ImL
0.1 mL
Source: FDEP, 1998.
Microbial Standards or Guidelines

Fecal coliforms are often utilized by regulatory agencies as indicators of fecal wastes,
effectiveness of disinfection, and water quality. Florida regulations for water quality and
wastewater treatment and disinfection utilize fecal coliforms. Disinfection and water
quality standards involving fecal coliforms are summarized in Table 4-13 (from FDEP,
1998).
                                      4-48

-------
Table 4-13.   Coliform Standards
Fecal Coliform
Limit (No./ 100 mL)
200"
200b
200"
200
14a
14b
4C
< Detection"
< Detection6
Application
Basic disinfection (minimum required for surface-water
discharge of treated wastewater and for reuse projects)
Standard for Class I waters (drinking-water supplies)
Standard for Class III waters (recreational waters)
Bathing beach standard
Intermediate disinfection (required for discharge to
tributaries of Class II shellfish waters)
Standard for Class II shellfish waters
Groundwater standard
High-level disinfection required for reuse systems
permitted under part III, Chapter 62-610, FAC
Drinking-water standard
Florida
Administrative Code
62-302.530,
62-600.440(4)
62-302.530
62-302.530
Department of
Health regulates
62-600.440(6)
62-302.530
62-520.420(1)
62-600.440(5)
62-550.310(3)
Source: FDEP, 1998.
6   Annual and monthly limits; higher limits apply for weekly and single sample limits.
b   Monthly average limit; higher limits apply to a single sample. Total coliform limits also apply.
c   In terms of total coliforms.
d   At least 75% of all observations must be less than detection; no sample may exceed 25/100 mL.
e   In terms of total coliforms; some excursions above detection are allowed.
Microbial Concentrations Needed to Cause Risk

The DEP risk assessment of reuse of reclaimed water relied upon results from several
studies of potential microbial risks, in addition to its own risk analyses (Rose and
Carnahan, 1992; Rose et al., 1996; FDEP, 1998). These studies concluded that in order to
pose a 1  in 10,000 risk (also known as a 1 x 10"4 risk), pathogen concentrations in
reclaimed water would have to be as shown in Table 4-14. This table presents
concentrations of pathogens that would correspond to a risk of 1 in 10,000, for several
doses (100 mL for recreation,  100 mL for residential irrigation, 1 mL for irrigation of
public access areas, 0.1 mL for exposure to aerosols, converted to 1 liter and 100 liters
for comparison).
                                         4-49

-------
Table 4-14.   Pathogen Concentrations in Water Corresponding to 1 x 10-4 Risk
Microorganism
Cryptosporidiwn
Giardia
Rotavirus
Echovirus
Units
Oocysts
Cysts
PFU
PFU
Cone. Needed for 1 xlO-4 Risk
0,1 mL
22,000
5,000
165
50,000
ImL
2,200
500
16.5
5,000
10 mL
220
50
1.65
500
100 mL
22
5
0.165
50
1 liter
2.2
0.5
0.0165
5
100 liters
0.022
0.005
0.000165
0.05
Source: FDEP, 1998.
PFU = plaque-forming units
In this risk assessment of deep-well injection, the microbial concentrations that would
cause a  1 in  10,000 risk can be used to evaluate possible concentrations of microbial
pathogens at drinking-water receptors.

Microbial Transport in Groundwater

Transport of bacteria and viruses in groundwater has been documented by a number of
studies in various countries (Rehmann et al., 1999; Yates et al., 1985) and in the Florida
Keys (Paul et al., 1995). In such studies, microbial transport is generally assumed to be
passive, whereby the microorganism is passively carried in a stream of water, rather than
active, where the microorganism would actively move against an environmental gradient.
The actual distances covered by viruses (including phages) and bacteria in groundwater
moving through various geologic media are summarized in Table 4-15 (from Rehmann et
al., 1999 and authors therein). Travel distances for viruses, the smallest microorganisms,
range from 46 meters in gravel, sand, and silt to 1,600 meters in carbonate rocks in
Missouri. Travel distances for bacteria range from approximately 122 meters for Serratia
marcescens, Enterobacter  cloacae in fractured chalk deposits to 900 meters for Bacillus
sterothermophilus in gravel.
                                       4-50

-------
Table 4-15.   Microbial Transport in Aquifers
Microorganism
Phage T4
Phages T4, 174
Bacillus
ster other mophilus
E. coli
Type 2 Aerobacter
aerogenose 243
Coxsackie B3
Unidentified phage
Serratia marcescens,
Enterobacter cloacae
Poliovirus 1, 2, 3
Poliovtrus, Coxsackie
B3 and echovirus
Coliphage f2,
indigenous
enteroviruses, fecal
streptococcus
Echovirus 6, 21, 24,
and 25 and
unidentified viruses
Maximum
travel
distance (m)
1,600
920
900
350-830
680
408
400
122-366
60-270
250
183
45.7
Conditions
Carbonate rock,
Missouri
Gravel, New
Zealand
Gravel, New
Zealand
Sand with gravel,
pebbles, 4-8 m
thickness,
Kazakhstan
Sandstone, Great
Britain
Coarse sand with
fine gravel,
Babylon, New
York
Fine sand with
some gravel,
coarse sand, Lake
George, New York
Fractured chalk,
Great Britain
Sandstone, silt,
clay, Dan region,
Israel
Cohansey sand
with coarse gravel,
Vineland, New
Jersey
Silty sand and
gravel, Fort
Devens,
Massachusetts
Coarse sand with
fine gravel, 1-2%
silt, Holbrook,
New York
Hydraulic
conductivity
(m/day)


104
105


4.6-19.5



8.6

Mean pore
velocity
(m/day)


164+
(colloid
velocity is
200 m/day)
160
36-180

3-12





Reference
Fletcher and
Myers
(1974)
Noonan and
McNabb
(1979)
Martin and
Noonan
(1977)
Anan'ev
and Demin
(1971)
Martin and
Thomas
(1974)
Vaughn and
Landry
(1977)
Aulenbach
(1979)
Skilton and
Wheeler
(1988)
Idelovitch et
al.(1979)
Koerner and
Haws
(1979)
Schaub and
Sorver
(1977)
Vaughn and
Landry
(1977)
Source: Rehmann et al., 1999, Table 1.
                                        4-51

-------
When these travel distances for microorganisms are compared with typical depths of
injection wells in South Florida, which range from approximately 1,000 feet to more than
2,500 feet below the surface, it is apparent that microorganisms could be transported over
such depths if a vertical transport mechanism exists. Probable mechanisms for vertical
transport of effluent from injection pressure and buoyancy were described earlier. Thus,
there is a mechanism for transporting microorganisms in South Florida, and there is
information from other studies that microorganisms can be transported over distances in
moving groundwater that are comparable to the deep-injection well vertical travel
distances to drinking-water receptors.

Microbial Survival in Groundwater

A critical question is whether or not pathogenic microorganisms can survive long enough
in groundwater to remain viable or infective over the estimated travel times calculated for
effluent to reach the USDW and public water-supply wells. Under scenario 1 for porous
media flow, characterized by slower effluent migration through small pore spaces,
calculated travel times to the USDW range from 2 years in Pinellas County, to 342 years
in Brevard County, to 421 years in Dade County. Estimated travel times to hypothetical
public water-supply wells are even longer under scenario  1: 23 years in Pinellas County,
1,118 years in Brevard County, and 1,188 years in Dade County. Under scenario 2 for
preferential flow, characterized by more rapid effluent migration through larger fissures,
cracks, cavernous weathered voids, and channels, the travel times to the USDW range
from 170 days in Pinellas County to  14 years in Dade County and 86 years in Brevard
County. Estimated travel times to hypothetical public water-supply wells under scenario
2 are 6.4 years in Pinellas County, 30 years in Dade, and 136 years in Brevard.

Viability in particular is an important issue in risk assessment, because a number of
pathogenic microorganisms may still remain viable (capable of causing disease) even if
they can no longer reproduce or grow under laboratory culture conditions (Xu et al.,
1982; Elliott and Colwell, 1985). Thus, a laboratory study that uses culturability of
organisms alone as a measure of microbial risk, without a study of the viability or
infective capacity of the microbial cells, would not necessarily paint a full picture of
microbial risk. Studies of infective populations of microorganisms remaining after a
period of time or some treatment would more accurately depict risk. Examples of such
studies are given in Table 4-16, summarizing some values for time needed to inactivate
infective microorganisms in water.
                                       4-52

-------
Table 4-16.   Survival of Microorganisms in Water
Microorganism
Cryptosporidium
parvum
E. coll S-2
E. coli
Vibrio cholerae
Enteric viruses
(coxsackie viruses,
Hepatitis A viruses and
Norwalk-like virus)
Time elapsed
1 76 days
35 days
24 hours
13 days
60 days +
9 days
> 2 months
Inactivation
99% of infective populations hi
river water are inactivated
33% of infective populations
are inactivated hi sea water
86% decrease in infective
population after 24 hours of
exposure to 0.149 M solution
of ammonium
85% of cells are not culturable
in sterile estuarine water
(salinity 1 1 ppt)*
Cells are not culturable*
No culturable cells remain in
sterile estuarine water (salinity
Hppt)at4to6°C*
Viability remained during this
period; inactivation was not
observed
Reference
Robertson et al., 1992
Robertson et al., 1992
Bowman and Jenkins,
1996
Xuetal., 1982
Elliott and Colwell,
1985
Xu et a!., 1982
Rose et al., 2000
* Results indicate that nonculturable bacterial cells may still be viable.
These results indicate that under some conditions approximating subsurface temperatures
and other conditions, fecal coliforms (E. coli} can survive for at least 60 days (with some
remaining viability), that a small percentage (1%) of Cryptospororidium can survive for
176 days, and that some viruses can remain viable for 2 months or more.

Interestingly, exposure to a 0.149 M solution of ammonium significantly increased the
inactivation rate of Cryptosporidium after only 24 hours. This concentration of
ammonium is at least two orders of magnitude greater than the concentrations of
ammonium found in secondary-treated effluent. The effect of wastewater constituents on
survival of pathogenic microorganisms poses an interesting, but probably largely
unanswered, question for microbial risk assessment.

Another way to examine microbial survival in the environment is to look at microbial
inactivation rates. Because microbiologists typically are studying large numbers of
microorganisms rather than single cells, the rate of inactivation of a microorganism is
often expressed on a logarithmic basis as the logio decline in the viable or culturable
organisms per day:

       Inactivation rate r = -log (N/ NO) / days

       Where r — inactivation rate in logic /day
             N = number of viable or culturable microorganisms at a given time
             NO =  initial number of microorganisms
                                       4-53

-------
The higher the inactivation rate, the fewer the numbers of microorganisms remaining
after a period of time. Conversely, the lower the inactivation rate, the more
microorganisms remain after a period of time. An alternate way of expressing the
inactivation rate is in terms of the T9o, or the time needed to inactivate 1 log, or 90%, of
the microbial population. A 2-log decrease in the microbial population would correspond
to inactivation of 99% of the population.

Inactivation rates and T9os for different microorganisms are given in Table 4-17.
From these rates, it is apparent that Cryptosporidiutn survives relatively longer in the
environment, with Tgos numbered in hundreds of days, than many pathogenic bacteria or
viruses, whose Tgos are numbered in days or tens of days.

Table 4-17.   Inactivation Rates for Microorganisms in Aquatic Media
Microorganism
Cryptosporidium
parvum
Cryptosporidium
parvum
Fecal coliforms
Fecal streptococci
Fecal enterococci
Poliovirus
E. coll
E. coli
Poliovirus
Echovirus
Inactivation
Rate
(Ioe10/day)
0.005
0.01 to 0.024
0.03, 0.0384
0.0204
0.025 to 0.233
0.0456
0.049 to 0.1 02
0.1584
0.035 to 0.667
0.051 to 0.628
Corresponding
Todays)
200
100 to 41.7
33.3, 26.04
49.02
40.0 to 4.29
21.93
20.4 to 9.80
6.31
28.6 to 1.50
19.6 to 1.59
Conditions and days

From lamb wastes, incubated
in raw water (35 days)
Florida groundwater sample
at 22 °C
Florida groundwater sample
at 22 °C
From a sewage source,
incubated in raw water (0 to
42 days)
Florida groundwater sample
at 22 °C, in laboratory
From a sewage source,
incubated in raw water (0 to
42 days)
Florida groundwater sample
at 22 °C, in laboratory
Groundwater (unfiltered)
incubated at native
temperatures of 4 to 23 °C
(AZ, CA, NC, NY, XX, WI)
Groundwater (unfiltered)
incubated at temperatures of 4
to 23 °C (AZ, CA, NC, NY,
TX,WI)
Reference
Robertson et
al., 1992
Medema et
al., 1997
Bitton et al.,
1983
Bitton et al.,
1983
Medema et
al., 1997
Bitton etal.,
1983
Medema et
al., 1997
Bitton et al.,
1983
Yates et al.,
1990
Yates et al.,
1990
Reviewing the mean effluent travel times (Table 4-8) with microbial Tgos (as shown in
Table 4-17) shows that, if Cryptosporidium were present in treated wastewater, Pinellas
County has the potential to receive Cryptosporidium at its drinking-water receptors,
because travel times for effluent are on the order of hundreds of days to several years.
However, because Pinellas County treats injected wastewater to a higher standard than
secondary and also employs filtration, it is not likely that concentrations of
                                      4-54

-------
 Cryptosporidium in the treated effluent would be high enough to cause human health
 concerns.

 Under the highest-risk scenario, scenario 2 (preferential flow along fractures), effluent
 travel times to drinking-water receptors in Dade County are about a decade or so (10 to
 16 years) (Table 4-8). Ten years amounts to 3,650 days, or one order of magnitude longer
 than the T90 for Cryptosporidium, which is the time needed to inactivate 90% of the
 original Cryptosporidium population present.

 These numbers suggest that the chances for Cryptosporidium to survive long enough to
 reach drinking-water receptors in Dade County are low. No data are available concerning
 Cryptosporidium or Giardia concentrations in secondary-treated wastewater from South
 Florida, and therefore assessment of the risk from pathogenic protozoans cannot be
 completed. However, the published literature values for inactivation rates and Tgos
 suggests that there may be a small chance that Cryptosporidium contamination could
 occur //initial concentrations in secondary-treated effluent were high to begin with.

 Fecal coliforms and viruses pose concerns in deep-well injection. This is not because
 their survival times are long, but because their concentrations in unchlorinated effluent
 potentially may be high enough that, even if they become attenuated during transport,
 there may still be a significant number that survive the long transport distances. Also,
 virtually nothing is known concerning in situ growth of microorganisms in groundwater.

 Monitoring of fecal coliforms and virus concentrations in discharged effluent indicates
 that, for the most part, secondary-treated effluent meets the fecal coliform standard of no
 more than 200 colonies per 100 mL for secondary treatment. However, discharged
 secondary-treated effluent does not always meet the drinking-water standard, which is
 nondetect (Appendix 9). Thus, bacteria and viruses may pose risks to water quality in the
 USDW and in public water-supply wells if secondary effluent is not disinfected to
 nondetect levels.

No data are available concerning concentrations of pathogenic protozoans in secondary-
treated effluent from South Florida. However, because these microorganisms are not
 inactivated by chlorine but require filtration to be removed, neither of which is required
 for deep-well injection, they may be present in injected effluent in Dade and Brevard
 counties.

 These data on microbial survival times, inactivation rates, and various times of travel for
 effluent migration suggest that, in some cases, particularly if scenario  2-type preferential
 flow is occurring, that longer-lived pathogenic microorganisms may pose a finite risk.
 Microorganisms capable of forming resistant or durable cysts or oocysts or spores that
can survive longer  periods of time are of particular  concern. These include
 Cryptosporidium^ Microsporidium, Giardia, Clostridium, and a number of other
pathogenic microorganisms.
                                       4-55

-------
Another factor to consider in evaluating microbial risk is straining of microorganisms.
Scenario 1 involves porous media flow through fine pore spaces, which is likely to strain
or filter small particles or colloids such as microorganisms. If scenario 1 flow is the
predominant or sole type of flow at an injection well site, then it is unlikely that
pathogenic microorganisms could easily be transported through the subsurface.

Despite its short-modeled travel times for effluent migration, Pinellas County provides an
example of low human-health risk from pathogenic microorganisms from deep-well
injection. This is because Pinellas County treats wastewater to reclaimed-water standards
before injecting it into deep-injection wells. Reclaimed-water standards require secondary
treatment with basic disinfection, filtration, and high-level disinfection with chlorine.
Such treatment would generally result in potable water. Filtration, if properly done, is
effective at removing pathogenic protozoan cysts and oocysts (York et al., 2002). In
Pinellas County, monitoring data indicate that, while Cryptosporidium concentrations
may be higher than concentrations that pose a 1 in 10,000 risk (DEP, 1998), these
concentrations generally are lower than the DEP's recommended limits of 5.8 oocysts per
100 liters and 1.4 cysts per 100 liters for Cryptosporidium  and Giardia, respectively
(York et al., 2002). Thus, Pinellas County has the lowest risks associated with microbial
pathogens, because of its higher level of treatment, disinfection and filtration.

If migrating effluent that reaches drinking-water receptors  does not meet drinking-water
standards (for example, no detection of fecal coliforms), then actual risk would exist.
However, this risk assessment does not take into account drinking-water treatment that
would remove microbial pathogens.

4.9    Final Conceptual Model of Risk for Deep-Well Injection

Deep-well injection of treated municipal wastewater involves the injection of treated
wastewater beneath a confining layer of rock and beneath a USDW. Deep-injection wells
are regulated as Class I injection wells. In South Florida, injection is done at depths
ranging from approximately 1,000 feet to more than 2,500  feet deep. These depths are
below the shallow surficial aquifers (that is, the Biscayne Aquifer and an unnamed
surficial aquifer) that extend to depths of approximately 20 to more than 800 feet and
below the USDW.

Deep-well injection constitutes one of the most important and widely used methods of
municipal wastewater management in South Florida, in terms of permitted discharge
capacity. Overall, deep-well injection accounts for approximately 20%, or 0.44  billion
gallons per day, of the total wastewater management capacity in the entire state.

Treatment of wastewater destined for deep-well injection in Dade and Brevard counties
consists of secondary treatment with no disinfection, although backup disinfection
capability is required. In Pinellas County, wastewater is treated to reclaimed water
standards before being discharged into deep-injection wells. Reclaimed water standards
include secondary treatment with basic disinfection, filtration, and higher-level
disinfection.
                                       4-56

-------
This risk assessment and risk characterization is intended to provide a broad and
representative picture of potential human health and ecological risks posed by deep
injection of treated wastewater in different regions of South Florida. It is not intended to
serve as a detailed risk assessment of specific sites. Therefore, for this risk assessment,
three counties were selected for detailed risk analysis because they provide different and
representative hydrogeologic conditions for their geographic areas: Dade County,
Brevard County, and Pinellas County. These counties have significant wastewater
management needs because of their populations.

A generic conceptual model of potential risk was developed to help evaluate risks. This
model forms part of the  generic risk analysis framework (GRAF) for evaluating risk, akin
to a blueprint or conceptual plan for conducting a risk assessment. The generic
conceptual model provides a set of guidelines for describing,  analyzing, and
understanding generalized or potential risks. The evaluation of the model involves use of
specific information to examine whether the model is valid or not and to refine the model.
This results in a final conceptual model that describes and characterizes risks based on
specific information.

The generic conceptual model of potential human health and ecological risks was
developed based upon the fate and transport of discharged treated effluent and its
constituents in groundwater. A fate-and-transport approach to characterizing risk was
selected because risk does not exist without exposure to stressors. Analysis of the fate
and transport is an analysis of whether or not discharged effluent constituents can reach
drinking-water supplies  and pose risks to consumers. This involves an analysis and
characterization of the pathways traveled by discharged effluent through the subsurface,
analysis of the fate of chemical constituents and microorganisms as the effluent travels in
groundwater, and characterization of the risks if effluent constituents were to reach
drinking-water receptors (defined here as the USDW and public water-supply wells).

The analysis of groundwater transport evaluated two endpoints of possible transport
pathways:

    •       Scenario 1, flow through porous media characterized by primary porosity
    *       Scenario 2, preferential flow through fractures, cracks, or other conduits,
           characterized by secondary porosity.

These two scenarios represent the two extremes of possible groundwater transport.
Porous media flow involves groundwater movement through rocks or soil with many
small pore spaces, or primary porosity; slow seepage through loamy soil is an example of
porous media flow. Porous media flow typically occurs at slow rates. Conversely,
preferential flow involves more rapid flow of water along preexisting fractures, cracks,
channels, or other large conduits in rock, which constitutes secondary porosity [?]. (In
this risk assessment, scenario 2 does not incorporate porous media flow, because
evaluation of dual porosity is not feasible at this time).
                                       4-57

-------
Travel times for effluent water to travel through limestone to the USDW and to drinking-
water wells were calculated. Different travel times were calculated, using primary
porosity (scenario 1) and secondary porosity (scenario 2) and also based upon
information on formation thickness, hydraulic conductivities, and other hydrogeologic
parameters. Vertical travel times were used to calculate horizontal migration distances,
which represent the horizontal distance that discharged effluent would travel in
groundwater, given a vertical travel time.

Travel times for effluent constituents were also calculated; the latter may differ from
travel times for effluent water if effluent constituents become attenuated (decrease in
concentration) as the effluent migrates over time. If, on the other hand, effluent
constituents behave conservatively, then they do not experience any change in
concentration over time. Nitrate and ammonium were assumed to behave conservatively
in the absence of information on microbiological transformation processes in the deep
subsurface. Arsenic also was evaluated as a conservative constituent, based on its
chemical behavior under reducing conditions.

The yardsticks used to measure risk, called assessment endpoints, include regulatory
standards for water quality of treated effluent, groundwater, and drinking water MCLs.
Other standards or recommended guidelines for water quality were  also used, such as the
DEP's guidelines for pathogenic microorganisms (FDEP, 1998; York et al, 2002). An
assessment endpoint can be regarded as a concentration threshold or safe level above
which there is a risk of an adverse effect.

The chemical constituents of wastewater selected as representative stressors for the
analysis of fate of constituents included nutrients (nitrate, ammonium, phosphate), metals
(arsenic, copper), VOCs (tetrachloroethene), synthetic organic compounds (chlordane,
di(2-ethylhexyl)phthalate or DEPH), endocrine-disrupting compounds (DEPH), and
chlorination by-products (trihalomethanes, including chloroform). Microbial pathogens
or indicators of wastewater included representatives of bacteria, viruses, and pathogenic
protozoans (E. coli, total coliform counts,  rotaviruses, other enteric  viruses,
Cryptosporidium parvum, and Giardia lamblid).

These estimated fate and transport mechanisms were then compared with groundwater
monitoring information from injection-we 11 facilities.

The final conceptual model consists of the results of the evaluation  of the conceptual
model using site-specific, representative information wherever possible. The elements of
the  final conceptual model are described below.

4.9.1   Injection Pressure Head and Buoyancy Pressure

Vertical migration of effluent constituents depends on two major components: pressure
head from injection and pressure head from buoyancy. Pressure head from injection is a
result of injected effluent displacing native groundwater in the injection zone. Pressure
head from buoyancy is  a result of salinity and temperature differences between the
                                       4-58

-------
 injectate and native groundwater. Fluids that are more saline tend to be denser than fluids
 that are less saline. Warmer fluids tend to be less dense relative to cooler fluids.

 In each county (Dade, Pinellas and Brevard), the injection pressure head and pressure
 head from buoyancy was determined. Pressure head from injection is a governing
 component for vertical migration in Pinellas County. In Dade and Brevard counties, the
 pressure head from injection is considered to be negligible because of the hydrogeologic
 conditions (highly karstifled) found in the Boulder Zone (injection zone). Therefore, in
 these counties, pressure head from buoyancy is the governing component for vertical
 migration.

 4.9.2   Vertical Time of Travel

 In scenario 1 (porous media flow), the total vertical travel times to receptor wells in Dade
 and Brevard counties are in the magnitude of more than 1,000 years (Table 4-8). In Dade
 County, it is estimated that discharged effluent will require more than 600 years to travel
 through the intermediate confining unit. In Brevard County, the discharged effluent will
 require more than 500 years to travel through the Lower Floridan because of the
 thickness of the aquifer (more than 1,400 feet). In Pinellas County, because of the
 injection pressure and the relatively short travel distance (and aquifer thickness) the total
 estimated time of travel to reach a hypothetical receptor well is 23 years.

 Time to reach an USDW for scenario 1 is in the range of approximately 300 to 400 years
 in Brevard and Dade counties, respectively. In Pinellas County, the estimated travel time
 for effluent to reach the USDW is 2 years.

 In scenario 2 (bulk flow through preferential flow paths), the vertical travel time was
 predicted to be 1 to 2 orders of magnitude shorter than travel times predicted for scenario
 1 (Table 4-8). Scenario 2 represents flow through fractures or cracks and does not include
 primary porosity; such fractures can allow rising fluid to migrate through a confining
 unit. The travel times predicted to reach a receptor well in Dade, Brevard, and Pinellas
 counties are approximately 136, 30, and 6 years, respectively.

 The time to reach the USDW in scenario 2 is approximately one order of magnitude
 shorter than in scenario 1. In Dade and Brevard counties, the travel times to the USDW
 under scenario 2 are 14 and 86 years, respectively. Travel time is 170 days in Pinellas
 County.

 4.9.3   Horizontal Distance Traveled in a Given Travel Time

 Based on horizontal hydrogeologic conditions and estimated vertical travel times, the
 extent of horizontal migration was estimated for each county. For scenario 1, the
 expected horizontal migration in Dade County is approximately 16 miles. Dade County
has the furthest horizontal migration relative to Brevard and Pinellas counties, which
have an expected horizontal migration of 1.5 and 1.2 miles, respectively. For scenario 2,
as expected, Dade County has the furthest horizontal migration distance of 1.6 miles,
                                       4-59

-------
while Brevard and Pinellas counties have horizontal travel distances of 0.1 and 0.6 miles,
respectively.

4.9.4  Fate of Chemical Constituents

For both scenarios 1 and 2, final concentrations of all chemical constituents were
negligible or below drinking-water MCLs at representative USDWs and receptor wells.
Figure 4-10 shows the rate of reduction of all nonconservative chemical constituents over
a period of time. All nonconservative chemical constituents have negligible final
concentrations after 40 years. Final concentrations of conservative chemical constituents,
such as nitrate, ammonia, and arsenic, do not decrease, but because their initial
concentrations in treated effluent are below MCL or Lifetime Health Advisory limits,
their final concentrations are also below these limits. Therefore, they are not deemed to
present significant human health risks, although there may still be cause for some concern
because concentrations are occasionally near MCLs.

4.9.5  Comparison with Monitoring-Well Data

The scenarios described above represent two distinct scenarios of fluid flow occurring
separately (that is, porous media or bulk flow only). In limited areas with minimal rock
fracturing, porous media flow might occur alone. However, in general, flow through rock
fractures would not occur without concurrent porous media flow.

The monitoring data are consistent with both types of flow. This relationship is expressed
with slight differences in the different regions studied. In Pinellas County, steady and
gradual changes in concentrations over 20 years of operation indicate that preferential
pathways are present. These changes began to occur shortly after injection began, which
is consistent with the model's bulk flow travel time for this region. In Brevard County,
some changes have occurred more quickly than was predicted by the model, which is
indicative of bulk flow. In Dade County, changes have also occurred with greater rapidity
than predicted by the model. Instead of a steady concentration gradient like that detected
in the other two studied regions, there are discontinuities in both the vertical and
horizontal directions. Bulk flow through rock fractures may also be present, but it may be
moving at slower rates, similar to those predicted by the model.

4.9.6  Mechanical Integrity as a Risk Factor

As discussed above, monitoring data indicate that upward migration of injectate is likely
via both porous media and bulk flow in Pinellas and Brevard counties. Mechanical
integrity of the injection and monitoring wells in these regions does not appear to be a
significant risk.
                                       4-60

-------
                     a) Chloroform
0                    10
            Contaminant Travel Time (Year)
                     c) Chlordane
                          10         15
                 Contaminant Travel Time (Year)
                      e) Arsenic
 "6
 •2-0.05
 U 0.03 •
 I 0.02
     01234567
                 Contaminant Travel Time (Year)
                      g) Nitrate
 '£ 4
    01234567
              Contaminant Travel Time (Year)
                                                                  b) Tetrachlorethylene (PCE)
                                                                       5          10          15
                                                                        Contaminant Travel Time (Year)
                                                                   d) Di(2-ethylhexyl) Phthalate (DEHP)
                                                                    34567
                                                                    Contaminant Travel Time (Year)
                                                                        f) Ammonia
                                                                234567
                                                                    Contaminant Travel Time (Year)
                                                      Legend
                                                            Dade County
                                                            Pinellas County
                                                          ss Brevard County
                                                            MCL / Lifetime Health Advisory
Figure 4-8. Final Concentrations of Representative Stressors Versus Time
                                                  4-61

-------
4.9.7  Fate and Transport of Pathogenic Microorganisms

Because deep-well injection of wastewater does not require basic disinfection or
filtration, there is a potential risk of microbial contamination of the USDW and possibly
of public water-supply wells. Microorganisms (bacteria, viruses, protozoans) are capable
of being transported in groundwater over distances comparable to the vertical and
horizontal travel distances that effluent must travel in order to reach the USDW and
wells.

Microbial inactivation rates for bacteria and viruses range from several days to tens of
days for a 1 log reduction in microbial activity (equivalent to 90% inactivation). For
injection wells that are experiencing fluid migration into the USDW because of rapid
preferential flow, bacteria and viruses may pose some cause for concern.

Microbial inactivation rates for Cryptosporidium, one of the more resistant and long-lived
pathogenic microorganism identified in water, are in the range of 200 days for a 1 log
reduction, corresponding to 90% inactivation of the population present. This slow rate of
inactivation means that chlorine-resistant pathogens like Cryptosporidium may be
capable of surviving long enough to reach USDWs if travel times are on the order of
months to several years.

The longer the vertical travel time, the more chance that natural inactivation of microbial
activity will occur. Thus, Pinellas County, with its short travel times of several years,
would appear to be at highest risk. However, Pinellas County employs basic disinfection,
filtration, and high-level disinfection, in addition to secondary treatment. In Pinellas
County, the quality of treated effluent is virtually that of drinking water. For these
reasons, its risk from microbial pathogens is probably the lowest of the three counties
evaluated.

Because basic disinfection and filtration are not done, Dade and Brevard counties, despite
travel times of several decades or longer, may be at some risk from long-lived or
especially resistant microorganisms or from those that can survive in an inactive state for
long periods of time. Effluent quality from secondary treatment without basic disinfection
or further disinfection would not meet drinking-water standards (no detection of fecal
coliforms). No information is available concerning concentrations of Cryptosporidium or
Giardia in such wastewater from South Florida, but it may be assumed that without
disinfection and filtration, concentrations of these cyst-forming protozoans may be
significant.

Scenario 2 (preferential flow) poses the highest potential human-health risk from
microbial pathogens. Scenario 1 (porous media flow) poses low or very low potential
human-health risk from microbial pathogens because of the long travel times, the fact that
it is unlikely that microorganisms would survive long enough to reach receptors (unless
there is in situ growth), and the fact that primary porosity may act to filter
microorganisms and retain them. Fluid movement of effluent from injection wells with
                                       4-62

-------
mechanical integrity issues could also pose higher risks, because it would promote
preferential flow.

4.9.8  Effects of Data Gaps

There are significant gaps in completeness of geographic coverage for monitoring-well
data and effluent quality. Nevertheless, this risk assessment is useful on a regional basis,
because values of parameters were selected to be representative of a wide range of
possible values. There do not appear to be any monitoring wells in the Biscayne Aquifer,
which represents a significant gap in information that would be useful for evaluating risks
in the surficial aquifer from deep-well injection and aquifer recharge. There are no
monitoring data on unregulated constituents of wastewater, such as endocrine-disrupting
compounds.

The area of groundwater microbiology represents a scientific frontier in microbial
ecology. This is to say, there is a severe shortage of information on microbial pathogens,
other than fecal coliforms, in groundwater and in deeper aquifers in South Florida. This
may be in part because monitoring for other types of microorganisms is not required, but
it is also because in situ microbial ecological studies  are difficult to conduct.  Information
that would be useful for a full and complete microbial risk assessment includes in situ
rates of inactivation in groundwater; concentrations of pathogenic protozoans, viruses,
and bacteria in groundwater and their viability; tracer studies to examine the  sources of
microbial contamination of groundwater; and time-series studies of microbially mediated
chemical transformations in situ.

The lack of information  on microbial biogeochemical processes in the deep subsurface
also causes the analysis of fate of chemical constituents to be incomplete, at least for
compounds that may undergo microbially mediated transformations. Examples of these
include denitrification, nitrification, oxidation, reduction, volatilization, and other
processes that can affect concentrations of metals, organic compounds, and nutrients.
Indeed, weathering of rocks and soil is largely accomplished through such microbial
transformations.

This risk assessment did not evaluate whether or not deep-injection fluids could be
transported to coastal areas and to marine waters. Wastewater effluent appears to migrate
from some shallow Class V injection wells and from  onsite sewage-disposal systems
(septic systems) into coastal ecosystems in  the Florida Keys, based on tracer studies of
nutrients. However, there is no corresponding tracer study of deep-injection fluids.

This risk assessment also did not account for cumulative risks from this wastewater
management option and  other sources of the same chemical and microbial stressors on
the surface.
                                       4-63

-------
REFERENCES

Adams K. 1992. A three dimensional finite difference flow model of the Surficial
       Aquifer in Martin County, Florida. SFWMD Technical Publication 92-02.

Anan'ev NI, and Demin ND. 1971. On the spread of pollutants in subsurface waters,
       Hyg. Sanit, 36:292-294.

Aulenbach DB. 1979. Long-Term Recharge of Trickling Filter Effluent into Sand. Rep.
       EPA-600/2-79-068. Ada (OK): US EPA.

Barr GL.  1996. Hydrogeology of the Surficial and Intermediate Aquifer Systems in
       Sarasota and Adjacent Counties, Florida. USGS WR1 96-4063. Reston (VA):
       USGS.

BC&E and CH2M Hill. 1977. Drilling and Testing of the Test-Injection Well Prepared
      for the Miami-Dade  Water and Sewer Authority. EPA Contract No. C120377020.

Beard PJ. 1940. Longevity of Eberthella typhosus in various soils. American Journal of
       Public Health 30: 1077.

Bitton G, Farrah SR, Ruskin RH, Butner J, and Chou YJ. 1983. Survival of pathogenic
       and indicator organisms in groundwater. Ground Water. 21:405-410.

Blackburn TH. 1980. Seasonal variations in the rate of organic-N mineralization in
       anoxic marine sediments. In: Biogeochimie de la Matiere Organique al'Interface
       Eau-Sediment Marin. Edition du Center National se la Recherche Scientifique.
       Paris: Colloque International C.N.R.S.

Bowman  DD and Jenkins MB. 1996. The effects of ammonia on the viability of
       Cryptosporidium parvum as determined by a dye-permeability assay. Paper: 45th
       Annual Meeting, American Society of Tropical Medicine and Hygiene. 1996;
       Baltimore, MD.

Broska JC and Barnette HL. 1999. Hydrogeology And Analysis Of Aquifer
       Characteristics In West-Central Pinellas County, Florida. USGS OFR 99-185.

Bush PW. and Johnston RH. 1988. Ground-Water Hydraulics, Regional Flow, and
       Ground-Water Development of the Floridan Aquifer System in Florida, and in
       Parts of Georgia, South Carolina, and Alabama. USGS Professional Paper 1403-
       B. Reston  (VA): USGS.

Camp, Dresser, McKee, Inc. 1992. Point-/Nonpoint Source Pollution Loading
       Assessment. Phase I. Final Report. Sarasota (FL): Sarasota Bay National Estuary
       Program.
                                     4-64

-------
CH2M Hill. 1977. Drilling and Testing of the Test-Injection Well for the Miami-Dade
       Water and Sewer Authority. EPA Contract No. C120377020. Gainesville (FL):
       CH2M Hill.

CH2M Hill. 1981. Drilling and Testing of the 8 Injection Wells and the 3 Monitoring
       Wells for the South District Regional Wastewater Treatment Plant of the Miami-
       Dade Water and Sewer Authority, Dade County, Florida. EPA Contract No.
       C120377020. Gainesville (FL): CH2M Hill.

CH2M Hill. 2001. Annual summary report of the City of St. Petersburg's Four Water
       Reclamation Facilities' Deep Injection Well System (January 1999 through
       December 1999). Tampa (FL): CH2M HILL.

Duerr AD. 1995. Types of secondary porosity of carbonate rocks in injection and test
       wells in Southern Peninsular Florida. USGS WRI 94-4013. Reston (VA): USGS.

Duerr AD and Enos GM. 1991. Hydrogeology of the Intermediate Aquifer System and
       Upper Floridan Aquifer, Hardee and De Soto Counties, Florida. USGS WRI 90-
       4104. Reston (VA): USGS.

Duncan JG, Evans WL, and Taylor KL. 1994. Geologic framework of the lower Floridan
      Aquifer System, Brevard County, Florida. Bulletin No. 64. Florida Geological
       Survey, Florida Department of Environmental Protection.

Earle JE, and Meyer FW. 1973. Reconnaissance of the water resources in the vicinity of
      proposed deep-well injection sites in southeast Dade County, Florida. USGS
      WRI 78-73. Reston (VA): USGS.

Elliot EL and Colwell RR. 1985. Indicator organisms for estuarine and marine waters.
      FEMS Microbiology Reviews. 32: 61-79.

Englehardt JD, Amy VP, Bloettscher F, Chin DA, Fleming LE, Gokgoz S, Rose JB,
      Solo-Gabriele H, and Tchobanoglons G. 2001. Comparative Assessment of
      Human and Ecological Impacts Form Municipal  Wastewater Disposal Methods
      in Southeast Florida. University of Miami. Submitted to the Florida Water
      Environmental Association Utility Council.

Fenchel TH. 1983. The Microbial Nitrogen Cycle. In: Microbial Geochemistry.
      Krumbein WE, ed. Boston: Blackwell Scientific Publications.

Fetter CW. 1994. Applied Hydrogeology. 3rd ed. New York: Macmillan College
      Publishing Company, Inc.

Fish JE and Stewart M. 1991. Hydrogeology of the Surflcial Aquifer System,  Dade
      County, Florida:  USGS WRI 90-4108. Reston(VA): USGS.
                                     4-65

-------
Fletcher MW and Myers RL. 1974. Groundwater tracing in karst terrain using phase T-4.
       Paper: Annual Meeting, American Society of Microbiology; Chicago, 111.

[FDEP] Florida Department of Environmental Protection.  1996. Florida Administrative
       Code Chapter 62-600, Domestic Wastewater Facilities

	. 1997. Memorandum to Mimi Drew, Director of the Division of Water
       Facilities through Richard Drew, Chief, Bureau of Wastewater Facilities, from
       Elsa A. Plotts, P.E., Administrator, FL DEP, Domestic Wastewater Section. Re:
       Recommendations of the UIC Class I Fluid Movement Workgroup.

	. 1998. Risk Impact Statement: Phase II Revisions to Chapter 62-610, F.A.C.
       Docket No. 95-08R.
      	. 1999a. Miami-Dade Water and Sewer Department, North District
       Wastewater Treatment Plant Application to Construct/Operate/Abandon Class I,
       III, or V Injection Well System, Class I Injection Well Operation Permit for
       Injection Well No. IW-2N.
          . 1999b. Florida Administrative Code Chapter 62-528, Underground Injection
       Control.
          . 2001. Department of Environmental Protection Discharge Monitoring Report
       - Part A, South Beaches Wastewater Treatment Facility.

      	. 2002. Map of Class I injection well facilities and status
Florida Department of Regulation, 1989. St. Petersburg Public Utilities Department -
       Albert Whitted Waste Water Treatment Plant Application to
       Construct/Operate/Abandon Class I, III, or V Injection Well System.

Freeze RA and Cherry JA. 1979. Ground Water. Englewood Cliffs (NJ): Prentice-Hall.

Gerba CP and Bitton G. 1984. Microbial pollutants: their survival and transport pattern to
       groundwater. In: Grounchvater Pollution Microbiology. Bitton G. and Gerba CP.
       eds. New York; John Wiley & Sons.

Gilbert RG, Gerba CP, Rice RC, Bouwer H, Wallis C, and Melnick JL. 1976. Virus and
       bacteria removal from wastewater by land treatment. Applied and Environmental
       Microbiology. 32: 333.

Gray TRG, and Parkinson D, eds. 1968. The Ecology of Soil Bacteria. University of
       Toronto Press.

Gupta RS. 1995. Hydrology & Hydraulic Systems. Prospect Heights (IL): Waveland
       Press, Inc.
                                     4-66

-------
Haberfeld JL. 1991. Hydrogeology of effluent disposal zones, Floridan Aquifer, South
       Florida. Ground Water. 29( 2): 186-190.

Hickey JJ. 1982. Hydrogeology and Results of Injection Tests at Waste Injection Test
       Sites In Pinellas County, Florida. USGS WSP 2183. Reston (VA): USGS.

Horsley & Witten, Inc. 2000. On-site Sewage Disposal Systems Pollutant Loading
       Evaluation - Test and Validation of the Indian River Lagoon Nitrogen Model.

Howard PH, Boethling RS, Jarvis WF, Meylan WM, Michalenko EM, 1991. Handbook
       of Environmental Degradation Rates. Boca Raton (FL): CRC Press LLC.

Hutchinson CB. 1991. Assessment of Hydrogeologic Conditions with Emphasis on Water
       Quality And Wastewater Injection, Southwest Sarasota And West Charlotte
       Counties, Florida. USGS OFR 90-709. Reston (VA): USGS.

Hutchinson CB, Sanders GL, and Duerr AD. 1993. Underground Injection in Southwest
       Florida. Video Corresponding to above abstract.

Hutchinson CB and Trammer JT. 1992. Model analysis of hydraulic properties of a leaky
       aquifer system, Sarasota County, Florida. USGS WSP 2340. Reston (VA):
       USGS.

Hwang NHC, Hita CE. 1987. Fundamentals of Hydraulic Engineering Systems.2nd ed.
       Englewood Cliffs (NJ):  Prentice Hall, Inc.

Idelovitch E, et al. 1979. Dan Region Project, Ground-water Recharge  With Municipal
       Effluent. Tel Aviv: Mekorot Water Co.

Jenkins MP, Bowman M, Walker and Ghiorse  W. 1997. Use of sentinel Cryptosporidium
       parvum oocysts to measure effects of passive manure storage on oocyst
       inactivation. Paper: 7' International Coccidiosis Conference, European Union
       COST 820 Workshop; Keble College, Oxford, England.

Jordan EO. 1926. The changes in bacterial content of stored normal and typhoid feces.
       Journal of Infectious Diseases. 38:306.

Knochenmus LA and Thompson TH. 1991. Hydrogeology and Simulated Development of
       the Brackish Ground-Water Resources  in Pinellas County, Florida. USGS WRI
       91-4026. Reston (VA): USGS.

Knochenmus LA and Bowman  G. 1998. Transmissivity and water quality of water-
       producing zones in the intermediate aquifer system, Sarasota County, Florida.
       USGS WRI 98-4091. Reston (VA): USGS.
                                     4-67

-------
Koerner EL, and Haws DA. 1979. Long-Term Effects of Land Application of Domestic
       Wastewater: Vineland, New Jersey, Rapid Infiltration Site. Report No. EPA-
       600/2-79-072. Washington (DC): US EPA.

Lukasiewicz J and Adams KS. 1996. Hydrogeologic data and information collected from
       the Surficial and Floridian Aquifer Systems, Upper East Coast Planning Area.
       Technical Publication WRE #337. West Palm Beach (FL): South Florida Water
       Management District.

Maliva RG and Walker CW, 1998. Hydrogeology of deep-well disposal of liquid wastes
       in Southwestern Florida, USA. Hydrogeology Journal. 6(4):538-548.

Martin GN, and Noonan MJ. 1977. Effects of domestic wastewater disposal by land
       irrigation on groundwater quality of the central Canterbury Plains. Technical.
       Pub. 7. Christchurch, New Zealand: Water and Soil Division, Ministry Of Works
       and Development.

Martin R, and Thomas A. 1974. An example of the use of bacteriophage as a
       groundwater tracer. Journal of Hydrology. 23:73-78.

Mawdsley JL, Brooks AE, and Merry RJ. 1996. Movement of the protozoan pathogen
       Cryptosporidium parvum through three contrasting soil types. Biology of Fertile
McKinley RM. 2000. Comments On 21-Oct-1998 Temperature And Radioactive Tracer
       Surveys From Miami-Dade Water And Sewer Department Disposal Well #1-2 And
       Subsequent Long-Term Gamma-Ray Activity Data From Monitor Well # FA-11
       (Lower Zone).

McNeill DF. 2000. A Review of Upward Migration of Effluent Related to Subsurface
       Injection of Miami-Dade Water and Sewer South District Plant.

Medema GJ, Bahar M, and Schets FM. 1997. Survival of Cryptosporidium parvum,
       Escherichia coli, faecal enterococci and Clostridi urn perfringens in river water:
       influence of temperature and autochthonous microorganisms.  Water Science  and
       Technology. 35:249-252.

Meyer FW. 1984. Disposal of liquid wastes in cavernous dolostones beneath
       Southeastern Florida. In: Vol. 1 Hydrogeology ofKarstic Terrains, Case
       Histories. International Association of Hydrogeologists.

_ . 1989. Hydrogeology, Ground-Water Movement, and Subsurface Storage  in
       the Floridan Aquifer System in Southern Florida. USGS Prof. Paper 1403-G.
       Reston (VA): USGS.
                                     4-68

-------
 [MDSWAD] Miami-Dade Water and Sewer Authority Department. 1977. Drilling and
       Testing of the Test-Injection Well for the Miami-Dade Water and Sewer Authority.
       Contract no. S-153, Dade County, Florida, EPA Contract No. C120377020,
       Project No. 559-7601.

	.  1991. Drilling and Testing of 3 Injection Wells and 2 Monitoring Wells for
       the South District Regional Wastewater Treatment Plant. Contract No. S-330.

	. 1997. Engineering report, plugging and reconstruction of M.D.W.S., South
       District's multi-zone Monitor Well BZ-1.

Miller JA. 1997. Hydrogeology of Florida. In: The Geology of Florida. Randazzo AF and
       Jones DS, eds. Gainesville: University Press of Florida.

Montgomery JH. 2000. Ground water Chemicals Desk Reference. 3rd ed. Boca Raton
       (FL): CRC Press, LLC.

Noonan MJ, and McNabb JF.  1979. Contamination of Canterbury groundwater by
       viruses. In  The Quality and Movement of Groundwater in Alluvial Aquifers of
       New Zealand, Tech., Publ. 2. Noonan MM, ed. Canterbury, New Zealand:
       Department of Agriculture  and Microbiology, Lincoln College.

Paul JH, Rose JB,  Brown J, Shinn EA, Miller S, and Farrah SR. 1995. Viral tracer studies
       indicate contamination of marine waters by sewage disposal practices in Key
       Largo, Florida. Applied and Environmental Microbiology. 61: 2230-2234.

Randazzo, A.F. and D.S. Jones. 1997. The Geology of Florida. Gainesville: University
       Press of Florida.

Reese RS. 1994. Hydrogeology and the distribution and the origin of salinity in the
       Floridan Aquifer System, Southeastern Florida. USGS WRI 94-4010. Reston
       (VA): USGS.

Reese RS and Memburg SJ. 1999. Hydrogeology and the distribution of salinity in  the
       Floridan Aquifer System, Palm Beach County, Florida. USGS WRI 99-4061.
       Reston (VA): USGS.

Reese RS and Cunningham KJ. 2000. Hydrogeology of the Gray Limestone Aquifer in
       Southern Florida. USGS WRI 99-4213. Reston (VA): USGS.

Rehmann LL, Campbell and Welty C. 1999. Stochastic analysis of virus transport in
       aquifers. Water Resources Research. 35:1987-2006.

Robertson LJ, Campbell AT, and Smith HV. 1992. Survival of Cryptosporidium parvum
       oocysts under various environmental pressures. Applied and Environmental
       Microbiology. 58:3494-3500.
                                     4-69

-------
Rose JB, Haas CN, and Regli S. 1991. Risk assessment and control of waterborne
       giardiasis. American Journal of Public Health. 81(6):709-713.

Rose JB and Carnahan RP. 1992. Pathogen removal by full scale wastewater treatment. A
       report to the Florida Department of Environmental Protection. Tampa:
       University of South Florida.

Rose JB, Dickson  LJ, Farrah SR, and Carnahan RP. 1996. Removal of pathogenic and
       indicator microorganisms by a full-scale water reclamation facility. Water
       Research. 30:2785.

Rose JB, Griffin DW, and Nicosia LW. 2000. Virus Transport from Septic Tanks to
       Coastal Waters. Small Flows Quarterly. 1(3).

Schaub SA, and Sorber CA. 1977. Virus and bacteria removal from wastewater by rapid
       infiltration through soil. Applied and Environmental Microbiology, 33:609-619.

Singh UP, Eichler GE, Sproul CR, Garcia-Bengochea JI. 1983. Pump testing Boulder
       Zone Aquifer, South Florida. Journal of Hydraulic Engineering. 109(8):  1152-
       1160.

Skilton H and Wheeler D. 1988. Bacteriophage tracer experiments in groundwater.
       Journal of Applied Bacteriology. 65:387-395.

Smith JJ, Howington JP, and McFeters GA. 1994. Survival, physiological response, and
       recovery of enteric bacteria exposed to a polar marine environment. Applied and
       Environmental Microbiology. 60:2977-2984.

Sobsey MD. 1983. Transport and fate of viruses in soils. In: Microbial Health
       Considerations of Soil Disposal of Domestic Wastewater. Cincinnati (OH): US
       EPA.

[SDWWTP] South District Wastewater Treatment Plant. 1998. Monitoring Well Purging
       Report. Report No. A,

Starr RC, Green TS, and Hull LC. 2001. Evaluation of Confining Layer Integrity Beneath
       the South District Wastewater Treatment Plant, Miami-Dade Water and Sewer
       Department, Dade County, Florida. Idaho Falls (ID): Idaho National Engineering
       and Environmental Laboratory, Geoscience Research Department.

Suthersan SS. 2002. Natural and Enhanced Remediation Systems. Boca Raton (FL): CRC
       Press, LLC.

Tibbals CH.  1990. Hydrogeology of the Floridan Aquifer System in East-Central Florida.
       USGS Prof. Paper 1403-E. Restong (VA): USGS.
                                     4-70

-------
Tihansky AB and Knochenmus LA. 2001. Karst features and hydrogeology in West-
       central Florida-A field perspective. USGS WRI 01-4011. Reston(VA): USGS.

Tuffey TJ, Hunter TV, and Matulewich WA. 1974. Zones of nitrification. Bulletin of the
       American Water Research Association. 10:1-10.

[US EPA] United States Environmental Protection Agency. 1992. Ammonia Drinking
       Water Health Advisory. US EPA, NTIS#: PB92-135425, ERIC#: D-273.
       Washington (DC): US EPA.

	. 2000. Drinking Water Standards and Health Advisories. EPA 822-B-00-001,
       Washington (DC): US EPA.

	. 2002. Technical Fact Sheet on Nitrate/Nitrite. Internet:
       http ://www. epa. gov/safe water/dwh/t- ioc/nitrate s.html.

[USGS] United States Geological Survey. 2000. Distribution, Movement, and Fate of
       Nitrate in the Surficial Aquifer Beneath Citrus Groves, Indian River, Martin and
       St. Lucie Counties, Florida, 2000. WRI 00-4057. Reston (VA): USGS.

Van Donsel DJ, Geldreich EE, and Clarke NA. 1968. Seasonal variations in survival of
       indicator bacteria in soil and their contribution to stormwater pollution. Applied
       Microbiology. 15:1362.

Vanderborght JP, and Billen G. 1975. Vertical distribution of nitrate concentration in
       interstitial water of marine sediments with nitrification and denitrification.
       Limnology & Oceanography. 20:953-961.

Vaughn J, and Landry EF. 1977. Data Report: An Assessment of the Occurrence of
       Human Viruses in Long Island Aquatic Systems. Rep. BNL 50787. Upton (NY):
       Brookhaven National Laboratory, Department of Energy and the Environment.

Walker C. 1997. Dupont/Pinellas Membrane Research Facility. Application to Construct
       Class V, Group 8 Exploratory Injection Well. Missimer International, Inc.

Walker MJ, Montemagno CD, and Jenkins MB. 1998. Source water assessment and
       nonpoint sources of acutely toxic contaminants: A review of research related to
       survival and transport of Cryptosporidium parvum. Water Resources Research.
       34(12):3383-3392.

Yates MV and Yates SR. 1988. Modeling microbial fate in the subsurface environment.
       CRC Critical Reviews in Environmental Control. 17(4):307-344.

Yates MV, Stetzenbach LD, Gerba CP, and Sinclair NA. 1990. The effect of indigenous
       bacteria on virus survival in ground water. Journal of Environmental Science and
                                     4-71

-------
       Health, Part A - Environmental Science and Engineering and Toxic and
       Hazardous Substance Control. 25:81-100.

York DW, Menendez P, and Walker-Coleman L. 2002. Pathogens in reclaimed water:
       The Florida experience. 2002 Water Sources Conference.

York DW and Walker-Coleman L. 1999. Is it time for pathogen standards? In:
       Proceedings of the 1999 Florida Water Resources Conference. A WWA, FPCA,
       andFW&PCOA\ 1999 April 25-28; Tallahassee, Florida.

Xu HS, Roberts N, Singleton FL, Attwell RW, Grimes DJ, and Colwell RR.  1982.
       Survival and viability of nonculturable Escherichia coli and Vibrio cholerae in
       the estuarine and marine environment. Microbial Ecology. 8:313-323.
                                     4-72

-------
 5.0    AQUIFER RECHARGE

 This section develops and presents information that has been incorporated into the
 conceptual model describing risks associated with the aquifer recharge wastewater
 management option.

 5.1    Definition of Aquifer Recharge

 Aquifer recharge in its broadest sense refers to the replenishment or recharge of a
 groundwater aquifer. In Florida, a number of practices involving use of reclaimed water
 may be termed aquifer recharge. Reclaimed water is wastewater that has received at least
 secondary treatment and basic disinfection or better and that is reused after leaving a
 municipal wastewater treatment facility. Reuse means the application of reclaimed water
 for a beneficial purpose (FDEP, 2001b). Reuse of reclaimed water is strongly supported
 and instituted in state law to encourage water conservation (FDEP, 2001c). Beneficial
 uses include irrigation, recharge of groundwater through rapid- or slow-rate land
 application, and enhancement or creation of wetland habitat. Reuse does not include
 direct consumption of water by humans.

 The types of reuse allowed in Florida (FDEP, 1998) that involve aquifer recharge are
 listed below:

   •   Slow-rate land application systems (restricted public access)
   •   Rapid-rate land application systems
   •   Irrigation of public-access areas
   •   Rapid infiltration basins  (RIBs)
   •   Unlined storage ponds
   •   Discharge to wetlands that percolate to groundwater
   •   Septic tanks
   •   Injection to groundwater
   •   Aquifer storage and retrieval
   •   Injection for salinity barriers
   •   Deep injection wells.

The first seven uses of reclaimed water involve application of treated water on or near the
surface of the land, allowing percolation of the water to occur through soil.  The last four
uses of reclaimed water involve  active injection of treated wastewater or other water into
the ground at various depths. An example of the latter is aquifer storage and retrieval
(ASR). ASR typically involves the storage of excess drinking-water-quality water in a
subsurface aquifer for later recovery and use during periods when demand for drinking
water exceeds availability. Although reclaimed water may be used, ASR typically is not
used to dispose of treated wastewater but is instead aimed at temporarily storing drinking
water. Reuse that involves discharges of reclaimed water to surface water is described in
Chapter 7.
                                       5-1

-------
For this risk assessment, several types of reclaimed water reuse that may result in aquifer
recharge were evaluated. These include slow-rate land application systems (including
irrigation), rapid-rate land application systems (including RIBs and unlined storage
ponds), and wetland treatment systems. These types of aquifer recharge are characterized
by surface application of reclaimed water over an area and allowing the water to
percolate downward and outward from the point of application.

Other practices involving reuse of reclaimed water or use of drinking-water-quality water
were not evaluated in this risk assessment. These include Class V shallow-injection wells
for disposal of treated wastewater, ASR systems, salinity barriers, and septic systems.
Class V shallow-injection wells, which are regulated by federal and state regulations, are
used for disposal of industrial, as well as treated, municipal wastewater and were not
evaluated in this risk assessment. ASR was not evaluated because it often utilizes surface
water rather than reclaimed water, as described above. Salinity barriers were not
evaluated because they are not intended for disposal of wastewater. This risk assessment
does not address on-site sewage disposal systems such as septic systems, a wastewater
management option that serves about 25% of Florida's population. Nevertheless, where
reclaimed water is used for such purposes, the risk analysis presented here may be
applicable.

5.2    Use of Aquifer Recharge in South Florida

The Division of Water Resources Management of the Florida Department of
Environmental Protection (DEP) conducts yearly inventories of all active domestic
wastewater treatment facilities that provide reclaimed water for reuse. The DEP's 2000
Reuse Inventory lists facilities having permitted capacities of at least 0.1 million gallons
per day (mgd) or more and describes reuse activities throughout the state of Florida
(FDEP,2001a).

Types of reuse included in the DEP  inventory are irrigation of public-access areas,
landscape irrigation, agricultural  irrigation, groundwater recharge, indirect potable reuse,
industrial uses, wetlands, and other uses. Irrigation of public-access areas and landscapes
includes irrigation of golf courses, residential areas, and other public-access areas.
Agricultural irrigation includes irrigation of edible and inedible crops. Groundwater
recharge and indirect potable reuse includes RIBs, absorption fields, surface-water
augmentation, and injection. Industrial uses include those at the treatment plant or at
other facilities. Wetland uses include discharge to wetlands and creation or enhancement
of existing wetlands.

According to the 2000 Reuse Inventory (FDEP, 2001a),  the leading use of reclaimed
water in Florida is irrigation of public-access areas and landscapes (Tables 5-1 and 5-2),
totaling 107,123 acres, by far the largest area covered by any reuse activity. Agricultural
irrigation accounts for the second-largest area receiving reclaimed water (35,282 acres).
Groundwater recharge in Florida accounts for 7,418 acres, while wetland uses of
reclaimed water account for 4,791 acres. Altogether, 154,954 acres receive reclaimed
water through various types of reuse activities.
                                        5-2

-------
Table 5-1.    Reclaimed Water Reuse Activities in Florida
                   Reuse Type
 No. of
Systems1
Capacity
 (mgd)
Flow
(mgd)
 Area
(acres)
Public-access areas and landscape irrigation
Golf course irrigation
Residential irrigation
Other public-access areas
   Subtotal:2

Agricultural Irrigation
Edible crops
Other crops
   Subtotal:2

Groundwater recharge and indirect potable reuse
Rapid infiltration basins
Absorption fields
Surface-water augmentation
Injection
   Subtotal:2
179
82
98
359
21
96
117
169
20
0
1
241
163
99
503
54
133
187
171
8
0
10
108
95
44
247
35
73
108
85
3
0
8
46,730
39,896
20,497
107,123
14,414
20,868
35,282
6,969
449
NA
NA
     190
      189
     96
   7,418
Industrial
At treatment plant
At other facilities
   Subtotal:2
76
17
129
35
66
21
4
0
      93
     164
     87
Toilet flushing
Fire protection
Wetlands
Other uses
       3
       0
      14
      10
        0
        0
      66
        7
      0
      0
     32
      5
 NA
 NA
   4,791
    336
Totals:'
     427
    1,116
    575     154,954
'The numbers of facilities are not additive because a single facility may engage in one or more reuse activity.
2 Discrepancies in column totals are from internal rounding associated with the development of this summary table.
Source: FDEP.2001a.
                                              5-3

-------
Table 5-2.  Reuse Flows for Reuse Types in Florida DEP Districts and Water
            Management Districts
Districts
Irrigation
of Public-
access
Areas
(mgd)
Agricultur
al
Irrigation
(mgd)
Ground-
water
Recharge
(mgd)
Industrial
(mgd)
Wetland
Systems
and
Others
(mgd)
Totals
(mgd)
DEP Districts
Southeast (West
Palm Beach)
South (Fort Myers)
Southwest (Tampa)
Subtotal, DEP
districts in South
Florida study area
Central (Orlando)
Northeast
(Jacksonville)
Northwest
(Pensacola)
Totals, all DEP
districts
25.98
52.37
79.89
158.24
71.69
9.45
8.62
248.00
0.94
5.06
21.50
27.5
43.90
6.63
30.09
108.12
7.68
8.60
15.44
31.72
50.17
10.73
3.50
96.12
27.12
1.18
30.80
59.1
15.96
5.35
5.92
86.33
1.52
2.28
6.64
10.44
21.84
0.63
3.85
36.76
63.24
69.49
154.27
287.00
203.56
32.79
51.98
575.33
Water Management Districts
South Florida1
St. John's River2
Southwest Florida2
Northwest Florida
Suwannee River
Totals , all water
management
districts:
90.34
67.16
81.77
8.62
0.11
248.00
23.14
25.05
23.56
30.18
6.19
108.12
43.47
31.11
17.12
3.50
0.93
96.13
28.81
20.64
30.89
5.92
0.06
86.32
3.81
22.37
6.71
3.88
0.00
36.77
189.57
166.33
160.05
52.10
7.29
575.34
'The area covered by the South Florida Water Management District is smaller than the area of this study.
Approximately half of these water management districts are outside of the area of this study.
Source: FDEP,2001a.


As Table 5-2 indicates, use of reclaimed water for public-access areas accounts for the
largest flows of reclaimed water in Florida (248 mgd), followed by agricultural irrigation
(108.12 mgd), groundwater recharge (96.12 mgd),  industrial use (86.33 mgd), and
wetlands (36.76 mgd), based on DEP districts. In the South Florida study area, use of
reclaimed water for public access is also the leading use (158.24 mgd), followed by
industrial use (59.1  mgd), groundwater recharge (31.72 mgd), irrigation (27.5 mgd), and
wetlands (10.44 mgd), based on DEP districts.

The DEP 2001 Reuse Inventory states that Florida has 359 systems using reclaimed water
for irrigation of public-access areas and landscape irrigation, of which approximately
one-half (179) are golf-course irrigation systems. The other systems are nearly evenly
divided among those serving other public-access areas (98) and residential irrigation (82).
                                        5-4

-------
According to the Florida DEP, reuse of reclaimed water on golf courses accounts for 42
percent of all reuse in Florida (FDEP, 2002). Agricultural irrigation systems using
reclaimed water total 117. These two types of irrigation involve slow-rate land
application. Industrial systems total 93. In the category of ground water recharge, there
are 189 reuse systems utilizing rapid-rate land application (169 RIBs plus 20 absorption
fields), out of a total of 427 reuse systems in the state. There are 14 wetlands systems
using reclaimed water (see Table  5-1).

It is important to note that, to provide flexibility in meeting discharge requirements, a
wastewater treatment facility may utilize more than one wastewater management option.
Similarly, more than one type of reuse system may be used at a particular site (FDEP,
200 la).

5.3    Environment into Which Treated Wastewater is Discharged

Aquifer recharge involves surface infiltration and percolation of treated reclaimed
wastewater through soils and geologic media overlying the surficial aquifer or the
Biscayne Aquifer, depending on the location. In Dade County, the Biscayne Aquifer
receives recharge. In Pinellas and Brevard counties, the unnamed surficial aquifer
receives recharge. The Biscayne and surficial aquifers are described below. See chapters
2 and 4 for more detailed information on these aquifers.

5.3.1   Biscayne Aquifer System

The Biscayne Aquifer covers an area of approximately 4,000 square miles of South
Florida (USGS, 2000). This aquifer extends along the eastern coast from southern Dade
County into coastal Palm Beach County. It is located above the Floridan Aquifer,
separated by approximately 1,000 feet of low-permeability clay deposits. The Biscayne
Aquifer ranges in thickness from 50 to 830 feet and is composed of highly permeable
limestone or calcareous sandstone (Meyer, 1989; Reese, 1994; Maliva and Walker, 1998;
Reese and Memburg, 1999; Reese and Cunningham, 2000).

The Biscayne Aquifer system is the main source of water for Dade, Broward, and
southeastern Palm Beach counties and serves the cities of Boca Raton, Pompano Beach,
Fort Lauderdale, Hollywood, Hialeah, Miami, Miami Beach, and Homestead. According
to the U.S. Geological Survey, this aquifer is the sole source of drinking water for 3
million people. Because the Biscayne Aquifer lies close to the surface and is highly
permeable, it is highly susceptible to contamination.

5.3.2   Surficial Aquifer

In areas of South Florida outside the Biscayne Aquifer, the unnamed surficial aquifer is
used locally for community and public water supply. The surficial aquifer is composed of
relatively thin layers of sands and limestone. The surficial aquifer ranges in thickness
from 20 to 800 feet, reaching its greatest thickness in southeastern Florida (Adams, 1992;
Barr, 1996; Lukasiewicz and Adams, 1996; Reese and Cunningham, 2000). Although the
                                       5-5

-------
surficial aquifer yields relatively small volumes of water, it is an important source of
private water supplies (Miller, 1997).

5.4    Regulations and Requirements for Aquifer Recharge

The level of wastewater treatment required for various reuse options is specified in state
regulations, including chapters 62-600 of the Florida Administration Code (FAC)
(Domestic Wastewater Facilities), 62-610 FAC (Reuse of Reclaimed Water and Land
Applications), and 62-611 FAC (Wetland Applications).

In addition to required treatment levels, state regulations specify system design and
operational requirements regarding facility capacity, monitoring requirements, backup
systems, and setback distances. All potable and nonpotable water supply wells and
monitoring wells within a 0.5-mile radius of reclaimed-water facilities must be identified
in permit applications for reclaimed-water facilities. Engineering reports must
demonstrate that reclaimed water or effluents will not violate water quality standards.

Reclaimed-water systems may be located in  areas that have Class F-I, G-I, and G-II
groundwaters for potable-water use, as defined by Rule 62-520 FAC (DEP 1996 Ground
Water Standards and Exemptions). Reclaimed-water facilities are required by EPA Class
I reliability regulations to provide backup treatment and wastewater-holding capability in
the event that treatment is disrupted or interrupted. Redundant treatment, recirculation
and retreatment, and the use of holding ponds with extra capacity are examples of backup
treatment and retention methods.

Sampling for Cryptosporidium and Giardia is required for discharges that may
potentially affect Class I surface waters and is also required for groundwater recharge or
salinity-barrier-control discharges. Although there are no federal or state numerical
standards for pathogenic protozoans in reclaimed water, the Florida DEP recommends
that concentrations of Cryptosporidium and Giardia should not exceed 5.8 oocysts and
1.4 oocyst per 100 liters (L), respectively (York et al., 2002).

5.4.1   Slow-Rate Land Application Systems

Slow-rate land application involves the discharge of treated water to the land's surface
and the eventual percolation of this water through soils and rocks, leading to aquifer
recharge. To prevent surface runoff or ponding of the applied reclaimed water, hydraulic
loading rates are regulated. The loading rate  is established after considering the ability of
the plant and soil system to remove pollutants from the reclaimed water  and the
infiltration capacity and hydraulic conductivity of geologic materials underlying the
system. Slow-rate land application systems typically are designed with hydraulic loading
rates between 0.15 and 1.6 centimeters per day (cm/day) (US EPA, 1981; Metcalf and
Eddy, 1991; Water Environment Federation, 1992; Kadlec and Knight, 1996).

Slow-rate land application systems must have backup disposal methods for wet weather
conditions and when  water quality treatment standards are not met. During wet weather,
                                       5-6

-------
effluent may be discharged to storage areas or discharged through an alternative
permitted disposal system.

In restricted access areas, reclaimed water must be provided with secondary treatment
and basic disinfection. In public-access areas, reclaimed water must receive secondary
treatment with high-level disinfection, at a minimum. Concentrations of total suspended
solids must be reduced through methods such as filtration or addition of substances that
cause coagulation, such as polyelectrolytes. Filtration increases the effectiveness of
disinfection, particularly for removing cyst-forming pathogenic protozoans such as
Cryptosporidium parvum and Giardia lamblia. Because of the potential for public
exposure to many reuse projects, particular care is necessary to minimize the spread of
pathogens (FAC 62-610, Part III, Slow-Rate Land Application Systems: Public Access
Areas, Residential Irrigation, and Edible Crops).

All land application systems, whether slow-rate or rapid-rate, must maintain setback
distances to surface water and potable supply wells  to protect water quality and ensure
compliance with water quality and drinking-water standards. For example, RIBs,
percolation ponds, basins, trench embankments, and absorptions fields must be set 500
feet from potable-water wells or Class I or II waters. The setback distance to potable-
water wells can be reduced to 200 feet if high-level disinfection is provided, Class I
reliability is provided, and if soils hydrology, well construction, hydraulic loading rates,
reclaimed-water quality, and expected travel time of groundwater to the potable water
supply provides reasonable assurance that water quality standards will be met at the well
(FAC 62-610.521).

5.4.2   Rapid-Rate Land Application Systems

Rapid-rate land application also involves the discharge of treated water to the land's
surface and the eventual recharge of the underlying  aquifer. However, rapid-rate systems
have a much faster percolation rate than slow-rate systems. Rapid-rate systems are
typically designed with hydraulic loading rates between 1.6 and 25 cm/day over the area
of the basins (Kadlec and Knight,  1996). No wet-weather backup system is required for
rapid-rate land application. Rapid-rate land application systems are also required to meet
groundwater quality criteria at the edge of a zone of discharge.

Because of the potential for faster migration of discharged water, treatment standards for
rapid-rate systems are higher. For rapid-rate land application, Florida regulations require
secondary treatment with high-level disinfection (FAC 62-610). The following standards
of water quality must be met:

    •   Total suspended solids must be less than 5 milligrams per liter (mg/L) before
       disinfection
    •   Total nitrogen (total N) must be less than 10 mg/L
    •   Treatment must meet drinking-water standards.
                                       5-7

-------
High-level disinfection with filtration is effective at inactivating viruses, bacteria, and
pathogenic protozoans in reclaimed water, especially if monitoring for removal of
protozoans is conducted (York et al., 2002).

5.4.3  Wetland Systems

Florida's domestic wastewater-to-wetlands rule controls the quantity and quality of
treated wastewater discharged to wetlands while protecting the type, nature, and function
of wetlands. This is codified in chapter 62-611 FAC. The wastewater-to-wetlands rule
regulates the quality of water  discharged from wetlands to contiguous surface waters. It
also provides standards for water quality, vegetation, and wildlife to protect wetland
functions and values and establishes permitting and monitoring requirements for
discharges of treated wastewater to wetlands. This rule allows the use of constructed
wetlands and altered wetlands for discharge of treated wastewater to create and restore
wetlands (FDEP, 2001e).

Reclaimed wastewater that is  discharged to wetlands must undergo secondary treatment
with nitrification to further reduce the concentration of nitrogen. The treated reclaimed
wastewater must meet the following standards:

    •  Carbonaceous biochemical oxygen demand must be less than 5 mg/L
    •  Total suspended solids must be less than 5 mg/L
    •  Total nitrogen (as N) must be less than 3 mg/L
    •  Total phosphorus (as P) must be less than 1 mg/L.

Discharge to wetlands can be  beneficial in several ways. Wetlands provide additional
filtration to discharged waters, thereby improving effluent quality. Inputs of water help to
maintain the wetland ecosystem. In some locations (for example, the Wakodahatchee
Wetlands facility in Palm Beach County), rapid-rate land application systems have been
converted to wetland treatment systems. The Wakodahatchee Wetlands receive
approximately 2 mgd  of highly treated reclaimed water. This water serves to maintain
various types of wetland habitats for wildlife (FDEP, 200 le).

Treatment wetlands are prohibited within the boundaries of Class I or Class II waters
(designated as Outstanding Florida Waters), or areas of critical state concern, or when the
wetland is exclusively herbaceous. Groundwater and drinking-water quality standards are
not specifically referenced in the wetland applications regulations. However, secondary
treatment with nitrification generally assures that drinking-water standards will be met.
According to a recent review of data from Florida reclaimed-water facilities, treatment
systems that provide nitrification may also be more effective in removing pathogenic
protozoans (York et al., 2002). Monitoring for fecal coliforms as an indicator of
wastewater pathogens is required in treatment wetlands.

Disinfection of secondary-treated wastewater with chlorine (used in both basic
disinfection and high-level disinfection) is highly effective at inactivating nearly all
bacteria and viruses. Although there are no numerical water quality standards regulating
                                        5-i

-------
the concentrations of pathogenic protozoans in treated wastewater, the Florida DEP
recommends that no more than 5.8 Cryptosporidium oocysts per 100 L and no more than
1.4 Giardia cysts per 100 L be allowed in reclaimed water. Filtration is the preferred
method of removing pathogenic protozoans, although the DEP has found that filtration is
not always effective (York et al., 2002).

5.5    Problem Formulation

In this section, the potential risks that may be associated with the aquifer recharge
wastewater management option are described. In section 5.6, potential risks are analyzed.

In conducting the option-specific risk analysis for aquifer recharge, an effort was made to
focus upon those reuse practices that best fit the broad definition of aquifer recharge and
that are most widely used within the study area. Wetland systems, as well as rapid and
slow-rate land application systems, are each used within the study area. However, for
reasons outlined below, this option-specific risk analysis focused on rapid-rate land
application systems (RIBs).

5.5.1   Slow-Rate Land Application Systems

Slow-rate land application systems often involve the use of reclaimed water to irrigate
vegetated systems, which assist in wastewater polishing and disposal. Irrigation rates are
generally low or intermittent, allowing aerobic soil conditions to become established, if
not continually, at least intermittently. Aerobic conditions in turn allow the growth of
upland vegetation, which removes nutrients, filters wastewater solids, and creates more
permeable soils. Slow-rate land application  of treated wastewater is used throughout the
United States (Kadlec and Knight, 1996).

In South Florida, slow-rate land application nearly always means irrigation, including
irrigation of public-access areas and landscape areas (for example, golf courses, parks,
highway medians, and cemeteries), and agricultural irrigation. In addition to plant uptake
and evapotranspiration  (water loss to the atmosphere because of plant respiration), a
portion of the applied water may percolate to groundwater.

Following treatment, reclaimed water may still contain nutrients such as nitrogen,
phosphorus, and other substances that act as nutrients. If such reclaimed water is applied
to vegetated areas, additional nutrient removal can be expected because of uptake by
vegetation. Vegetation  is often used as a "polishing" agent to help remove nutrients in
wastewater treatment, and there are some wastewater treatment approaches that are based
largely upon the use of plants to remove nearly all pollutants. Wetland treatment systems
in particular rely heavily upon vegetation to remove or reduce pollutants.

The efficacy of removal of nutrients and other substances by plants depends upon many
factors, such as the rate of application, concentration of nutrients in the treated water
being applied to vegetation, plant species used, rate of nutrient uptake by plants,
microbial processes that may further affect uptake rates, soil type, moisture, pH,
                                       5-9

-------
temperature, whether other sources of nutrients also happen to be present, and length of
exposure time (Kadlec and Knight, 1996).

If the rate of nutrient application equals the total rate of uptake by vegetation and all other
uptake processes, then there should be little or no excess nutrients. Similarly,  if irrigation
with reclaimed water does not occur at a rate that exceeds the rate of uptake by vegetation
and all other uptake processes, there will be little or no recharge of groundwater. Reuse
systems that involve application to vegetated areas are typically operated so as to take
into account a specific water budget and assimilative capacity. However, if the plants'
capacity for water and nutrient uptake is less than the rate of application, excess water
and nutrients will percolate without the beneficial functions of nutrient removal and water
reuse that plants may provide.

Biodegradation of many wastewater constituents in soils and vegetation can also be
expected.  Biodegradation processes in soil include microbial uptake and transformation,
microbially mediated decomposition of organic matter, microbial volatilization or
solubilization, and further transformations as the breakdown products pass through the
food chain to higher organisms (Brock et  al., 1984; Kadlec and Knight,  1996).
Microorganisms are important in the biogeochemical cycling of biologically important
elements,  including carbon, nitrogen, phosphorus, sulfur, iron, manganese, and silica, and
play an important role in the decomposition of rocks and soils  (Krumbein et al., 1983).
Biological degradation of pesticides, petroleum products, metals, and other pollutants is
often accomplished through microbial processes (Kadlec and Knight, 1996).

Facilities operating  slow-rate land application systems are required to balance the
application of reclaimed water with evapotranspiration rates. Therefore, these facilities  do
not typically operate their land application systems during periods  of wet weather. Slow-
rate land application systems  are not likely to provide significant recharge to
groundwater. Risks are expected to be very low to nonexistent.

5.5.2  Rapid-Rate Land Application Systems

Rapid-rate land application systems discharge treated wastewater to RIBs and absorption
fields with highly permeable soils. RIBs involve a series of basins that may include
subsurface drains, which are designed to receive and distribute reclaimed water.
Absorption fields include subsurface absorption systems that may include leaching
trenches, pipes, or other conduits to receive and disperse water underground. They are
typically covered with soil and vegetation.

Rapid-rate application systems are typically loaded at hydraulic loading rates  between 1.6
and 25 cm/day over the area of the basins (Kadlec and Knight, 1996). Absorption fields
must be designed and operated to avoid saturated conditions at the  ground surface.
Projects proposed in areas with unfavorable hydrogeology (for example, karst) or other
unfavorable characteristics must meet additional levels of treatment, as described below.
                                       5-10

-------
 The use of rapid-rate land application may result in significant volumes of reclaimed
 water directly recharging the surficial aquifer. There is little potential for reduction in
 volume or additional removal of stressors by in situ natural attenuation processes,
 because of the large volumes applied and the rapid application rate. Because larger
 volumes of reclaimed water are applied and only an intermediate level of treatment is
 used, this form of aquifer recharge may pose the highest risks. Therefore, this option-
 specific risk analysis and risk assessment focuses on rapid-rate land application.

 5.5.3  Wetland Systems

 Wetlands, which are wet or inundated during part or  all of the year, are often transitional
 areas between uplands and permanently flooded aquatic basins, such as lakes, ponds,
 lagoons, or coastal embayments. Wetlands are characterized by vegetation that has
 adapted to living under wet or occasionally inundated conditions and by hydric soils that
 develop chemical and physical characteristics related to low oxygen and frequent or
 constant exposure to water (US Army Corps of Engineers, 1987; Dennison and Berry,
 1993; Cowardin et al., 1979). Wetlands are characterized by high rates of biological
 activity and productivity relative to upland ecosystems, making them capable of
 transforming and  neutralizing many of the constituents found in treated wastewater
 (Kadlec and Knight, 1996).

 Wetland systems or wetland treatment systems involve the application of reclaimed water
 to existing wetlands for the purpose of restoring wetlands and providing further treatment
 of water. Wetland reuse systems may provide more significant amounts of recharge to
 groundwater, particularly where there are direct hydrologic connections between the
 wetland and groundwater systems.

 However, where perched wetlands exist because of the presence of a relatively
 impermeable soil  layer (for example, clays, organic matter) that slows or prevents direct
 hydrologic connection with the underlying aquifer, a wetland may actually retard
 recharge of groundwater. The major difference between wetland systems receiving
 reclaimed water and all other types of aquifer recharge is that wetlands, particularly
 natural wetlands, will  typically contain more ecological receptors than human receptors.
 Because discharge to wetlands  is analogous to surface-water discharge of treated
 wastewater, the evaluation of risks from wetlands discharge is discussed in Chapter 7.

 5.5.4  Florida DEP Study of Relative Risks of Reuse

 In this risk assessment, information from a Florida DEP study of the risks of reclaimed
water was integrated into the fate and transport analysis (FDEP, 1998). The Florida DEP
 risk study provided a qualitative ranking of the relative human health risks of reuse of
 reclaimed water that involves release to surface water or groundwater used for drinking-
water supplies. The DEP study was intended to support state rulemaking. The qualitative
ranking of various reuse options was based on the best professional judgment of
professionals in regulatory agencies and other groups and on the IxlO"4 threshold for risk
(that is, there is a  l-in-10,000 chance of a stressor causing illness or other adverse effect
                                       5-11

-------
in consumers). However, according the DEP, the IxlO"4 risk threshold may not be
appropriate for defining microbial risk thresholds.

The DEP's relative-risk ranking assigns a relative risk from 1 (high) to low (25) for
various reuse activities using reclaimed wastewater. Injection of reclaimed water to
aquifers, aquifer storage and retrieval using reclaimed water, discharge to Class I  surface
waters (drinking-water sources), and injection for salinity barriers were rated as the six
highest-risk activities. Rapid-rate infiltration systems in karst (RIBs) ranked 7th,
discharge to surface waters hydrologically connected to groundwaters ranked 11th,
discharge to wetlands ranked 14th, rapid-rate infiltration systems in suitable geology
ranked 15th, slow-rate systems ranked 17th, and irrigation of public-access areas ranked
18th. The lowest risk ranking was assigned to lined storage ponds.

Based on the DEP's relative-risk ranking of various reuse options for reclaimed
wastewater, rapid-rate infiltration systems were selected as a higher-risk form of aquifer
recharge (excluding injection, ASR using reclaimed water, and salinity barriers) for this
risk assessment. Selection of a higher-risk form of aquifer recharge provides a
conservative or protective approach to risk assessment.

5.5.5  Potential Stressors

Potential Stressors entrained or dissolved in the reclaimed water are discharged to RIBs.
Wastewater constituents that may act as Stressors to human or ecological health include
pathogenic microorganisms, certain metals and inorganic substances, synthetic and
volatile organic compounds, and hormonally active agents.

Rapid-rate land application systems are required to meet groundwater quality criteria at
the lower edge of a discharge zone. Accordingly, most systems that utilize RIBs are
operated in such a way that concentrations of Stressors are substantially reduced before
reclaimed water reaches and recharges the underlying aquifers.

The primary source of potential Stressors is the effluent from wastewater treatment plants
(that is, reclaimed water) that is discharged through one or more aquifer recharge
facilities and eventually percolates to reach the underground surficial aquifer, a formation
containing underground sources of drinking water (USDWs). Stressors include reclaimed
water constituents such as metals and other inorganic elements; compounds  such as
inorganic nutrients (nitrate, ammonium, and phosphate); volatile and synthetic organic
compounds; microorganisms that survive basic or high-level disinfection or are resistant
to disinfection, such as pathogenic protozoans; and miscellaneous constituents.
Chlorination, and especially high-level disinfection, is effective at inactivating bacteria
and viruses; however, cyst-forming pathogenic protozoans, such as Cryptosporidium
parvum, Giardia lamblia^ are only removed through filtration designed for their removal
(York etal., 2002).

Potential risks associated with the use of emergency ponds to receive wastewater during
upset bypass conditions, such as storms or other events resulting in large volumes of
                                       5-12

-------
wastewater, can also be characterized using this conceptual model. Exposure pathways,
receptors, and assessment endpoints are similar; concentrations and types of stressors
may differ.

5.5.6  Potential Receptors and Assessment Endpoints

Potential drinking-water receptors include USDWs beneath the RIB, other USDWs to
which groundwater flow may carry potential stressors, public and private water-supply
wells, and surface waters. Federal drinking-water standards (maximum contaminant
levels ( MCLs)) and other health-based standards serve as the analysis endpoints for
assessing risks to each of these potential drinking water receptors.

The USDWs that may be recharged by RIBs include the unnamed surficial aquifers and
the Biscayne Aquifer. The surficial aquifers are used for domestic private water supplies
and for municipal water supplies in central South Florida and along the east  and west
coasts (Randazzo and Jones, 1997). The Biscayne Aquifer is tapped by private wells and
also supplies large public water systems in Dade, Broward,  and Palm Beach counties.
Water obtained through private wells is often used directly (without pretreatnient).
Community and municipal water systems generally do pretreat groundwater before
distribution.

Utilities in South Florida make limited use of surface water bodies as sources of drinking
water. Nevertheless, migration of wastewater constituents to these sources of drinking
water is a possibility; surface water bodies  are potential drinking-water receptors.

Potential ecological receptors include surface water bodies and the biological
communities they support. The state of Florida surface-water quality standards for Class I
waters and known ecological dose-response thresholds serve as the assessment endpoints
for assessing risks to potential ecological receptors.

5.5.7   Potential Exposure Pathways

When drinking-water or ecological receptors are exposed to wastewater constituents in
sufficient concentration, these receptors may be at risk for potentially adverse health
effects. The  complex set of processes and interactions  that govern how reclaimed water
will move and behave in the  subsurface define the pathways that may expose receptors to
such concentrations.

Dissolved and entrained wastewater constituents move through soils and geologic media
under the influence of physical, chemical, and biological processes. These processes
govern the movement of water and the fate and transport of stressors present in the water.
Pathways of reclaimed-water migration, and the processes that may modify its
constituents, are dependent upon both the hydrogeologic system into which the reclaimed
water has been recharged  and the nature of the constituents themselves.
                                       5-13

-------
Conservative (nonreactive) constituents will move through the hydrogeologic system
unaffected by chemical or biological processes. Concentrations of conservative
constituents are diluted in groundwater through advection (groundwater flow) or
diffusion. On the other hand, concentrations of wastewater constituents that are subject to
chemical and biological transformation will be influenced by abiotic processes (that is,
ion exchange, adsorption), by biological degradation or transformation, and by dilution in
the subsurface.

The highly permeable limestone formations of the Biscayne Aquifer and the less
permeable formations of the surficial aquifers provide pathways for migration of
reclaimed-water and wastewater constituents. Groundwater transport of these constituents
may result in migration from the point of recharge to a receptor well or surface water
body.

Following recharge, inorganic and organic wastewater constituents that are not removed
by the treatment process will be entrained in the effluent. As the effluent moves through
the subsurface soil and rocks during advection, these constituents will be subject to a
number of physical, chemical, and biological processes such as dilution, absorption,
chemical transformation, volatilization, and other processes.

5.5.8   Conceptual Model of Potential Risks of Aquifer Recharge

A generic conceptual model for the aquifer recharge wastewater-management option is
presented in Figure 5-1. The primary source of potential stressors is defined as the
wastewater treatment plant from which reclaimed water is distributed to one or more
rapid-rate land application systems.

Reclaimed water is discharged to RIBs located directly above surficial aquifers. RIBs are
generally located tens of feet (not hundreds or thousands of feet) above the water tables
receiving the recharge. Underlying surficial aquifers are typically USDWs of potable-
water quality (less than 1,500 mg/L total dissolved solids content).

For aquifer recharge, the expected principal exposure pathway is migration of reclaimed
water from the point of recharge by rapid-rate land application systems to the USDW.
Groundwater may also carry reclaimed-water constituents to areas where groundwater
discharges to surface water, potentially affecting ecological receptors.
                                       5-14

-------
       Primary
        Source
     Potential
System Stressors
   Reclaimed Water
       Treatment
    Plant Discharge
      Rapid-Rate
        Aquifer
       Recharge
                                   Inorganic
                                   Constituents
                                  Volatile Organic
                                  Constituents
  Synthetic Organic
  Constituents
                                  Microbiological
                                  Constituents
                                  Miscellaneous
                                  Constituents
 Pathways / Processes
                          Physical Processes

                            Ground Water Flow
                            Dilution due to Advection
                            and Diffusion
                            Adsorption / Desorption
                            Filtration by Soil and
                            Geologic Media
                            Ground Water Contribution
                            to Surface Water Bodies
Chemical Processes

  Precipitation / Dissolution
  Oxidation / Reduction
  Chemical Transformation
  Complex Formation
                           Biological Processes

                           Mortality vs. Survival
                           Growth
                           Biodegradation
                           Microbial Inactivation
 Potential Receptors
USDW
Drinking Water WelJs
 (Municipal and Private)
Irrigation Wells
Surface Water
 Phytoplankton and Zoopiankton
 Submerged Aquatic Vegetation (SAV)
 Macroi nvertebrates
 Fish
 Aquatic and Terrestrial Birds
 Aquatic and Terrestrial Mammals
 Reptiles and Amphibians
 Endangered Species
 Humans
  Potential Effects
Ecological
  Eutrophieation (excess nutrients and algal
    growth, low oxygen) :
  Harmful Algal Blooms (HABs)
  Changes in Phytoplankton and Zoopiankton
    Communities
  Toxic Effects on Aquatic and Terrestrial
    Species   .
  Developmental or Reproductive Changes in
    Aquatic or Terrestrial Organisms
  Reduced Growth of SAV due to Reduction
    in Water Clarity
  Food Web Effects
Human Health
Figure 5-1.  Conceptual Model of Potential Risks for the Aquifer Recharge Option

-------
The dissolved and entrained constituents move through the geologic media under the
influence of physical, chemical, and biological processes governing water movement and
the fate and transport of the stressors in groundwater. The surficial aquifer may also act
as a secondary source of dissolved and entrained stressors that may be carried to other
parts of the aquifer where receptors may be exposed.

5.6    Risk Analysis of the Aquifer Recharge Option

In this section, information on stressors, receptors, and exposure pathways are used to
examine potential risks and evaluate the conceptual model for aquifer recharge.

This analysis evaluates how reclaimed water may be transported horizontally within
USDWs away from the point of recharge. Estimated times of travel are used to
characterize the fate and transport of wastewater constituents (stressors) present in the
reclaimed water. The fate and transport equations used in chapter 4 for evaluation of deep
injection-well disposal are valid for aquifer recharge as well.

Information concerning potential stressors was obtained from effluent water quality
monitoring reports required by the state of Florida and from a review of the scientific
literature. To describe the proximity and vulnerability of receptors, publicly available
information was obtained regarding the locations of public water-supply intakes. A
review of the scientific literature provided information regarding the locations and
physical extent of USDWs in South Florida. Information necessary to characterize
possible exposure pathways was obtained from scientific literature describing the study
area's soils, geology, and hydrology.

5.6.1   Vertical  and Horizontal Times of Travel

Analyzing the transport of discharged effluent involves the analysis of the time of travel,
which is the time needed for discharged effluent to move in groundwater over a specified
distance to  a drinking-water receptor. In aquifer recharge,  typically the discharge location
is directly above the surficial aquifer, and therefore the migration pathway will be
downward and outward from the point of application. The potential for migration will be
affected by site-specific factors, including the following:

    •   Required setback distances
    •   Locations of potential receptors (water-supply wells)
    •   Local direction of groundwater flow
    •   The distance to potential receptor wells
    •   Surficial  aquifer characteristics that govern groundwater flow velocity.

Required setback distances vary depending on facility operations and range from 200,
500, and 2,640 feet. Engineering reports for new facilities must identify all potable water
supplies within 0.5 mile of the facility.
                                       5-16

-------
Representative hydrogeologic parameters for Dade, Brevard, and Pinellas counties were
used to estimate the potential groundwater flow velocity and associated time for
groundwater to travel 200 feet, 500 feet, and 0.5 mile (2,640 feet) in the surficial aquifer
(Adams, 1992; Barr, 1996; Lukasiewiez and Adams, 1996; Reese and Cunningham,
2000). Assumptions, calculations, and results are provided in appendix 8 and are
summarized in table 5-3. Since local hydrogeologic conditions in the surficial aquifer
may vary significantly, these travel times are intended only to provide representative
values.

Table 5-3.    Effluent Travel Times in the Surficial Aquifer
Surficial Aquifer Location
Dade County:
horizontal hydraulic conductivity: 1,524 ft/day
Brevard County:
horizontal hydraulic conductivity: 56 ft/day
Pinellas County:
horizontal hydraulic conductivity: 29 ft/day
Horizontal
Distance (ft)
200
500
2,640
200
500
2,640
200
500
2,640
Travel Time
Days
41
102
537
1,107
2,768
14,614
2,138
5,345
28,221
Years
0.11
0.28
1.47
3.03
7.58
40.01
5.85
14.63
77.26
Note: hydraulic gradient = 0.001; porosity = 0.32.
The results of these calculations (table 5-3) indicate that the shortest estimated travel
times for effluent to travel 200, 500, and 2,640 feet are predicted for Dade County, where
the Biscayne Aquifer has a high hydraulic conductivity. Horizontal travel time is
significantly longer, by approximately 2 orders of magnitude, in Brevard County. Pinellas
County has the longest horizontal travel times. These estimates are based on constant
porosity and constant hydraulic gradient, but varying hydraulic conductivity from region
to region. Again, site-specific conditions may  differ substantially from the values used.

These results indicate that, solely in terms of transport of effluent, the highest risks for
aquifer recharge may be found in Dade County, where the time of travel is the lowest,
and the lowest risks for aquifer recharge may occur in Pinellas County, where the time of
travel is the highest.

5.6.2   Evaluation of Stressors

Monitoring data indicates that concentrations of wastewater constituents in reclaimed
water used in aquifer recharge generally meet  drinking-water standards for reclaimed
water. Also, treated effluent generally meets or is better than standards for reclaimed
water or advanced wastewater treatment effluent (see Appendix Table 1-1).
                                       5-17

-------
Several representative chemical elements and compounds, potentially found in reclaimed
water recharged via rapid-rate systems, were chosen for fate and transport analysis. The
analysis is designed to estimate the final concentration of these wastewater constituents
by taking into account calculated travel times in groundwater, biodegradation, hydrolysis,
and sorption processes. These natural attenuation processes will reduce the overall
concentration of chemicals during transport in groundwater.

Examples of natural attenuation processes include sorption, biological degradation, and
chemical transformation. Compounds and elements dissolved in groundwater are
removed from solution by sorption onto geologic material. Such sorption-desorption
reactions result in a slowing of movement of the compound or element in groundwater.
Sorption may be reversible, however. Biological activity by microorganisms may also
result in the degradation of organic material and may also mediate transformations of
inorganic materials, resulting in decreasing concentrations over time. Hydrolysis is
another process whereby organic and inorganic solutes react with water, resulting in
degradation and transformation. Rates of biological degradation and hydrolysis reactions
may be expressed as a half-life for specific compounds (that is, the time it takes the
concentration of the compound or element to decrease to one-half of its original
concentration).

Selected representative stressors included arsenic (As), chloroform (CHCla) (representing
trihalomethanes), nitrate (NOs), and di (2-ethyl) phthalate (DEPH). Chloroform and
several other similar compounds known as trihalomethanes may be present in reclaimed
water as a result of the chlorination process. The fate and transport characteristics of
chloroform were selected to represent the potential for migration of all trihalomethanes.
DEPH, a synthetic organic compound used as a plasticizer for polyvinylchloride (PVC)
and in consumer products, is a suspected endocrine disrupter (ASTDR, 1993).

Concentrations of representative compounds were based on typical values for reclaimed
water (presented in Table 5-4); these were obtained from a large data set of monitoring
results for treated effluent (see Appendix Table 1-1). The concentration of chloroform
was used as a representative of total trihalomethanes, a group of compounds that includes
chloroform. Chloroform was selected for the analysis based on the availability of fate and
transport information. All initial stressor concentrations in the data sets available met
drinking-water standards. The selected concentration for DEPH was the detection limit
reported for wastewater analyses.

Table 5-4.    Initial Concentration of Representative Stressors in Reclaimed Water
Compound
Arsenic
Chloroform
Di (2-ethylhexyl) Phthalate (DEPH)
Nitrate
Initial Concentration
0.003 mg/L
26.85' (Mg/L)
5.02(ng/L)
3.69 (mg/L)
'Concentration of total trihalomethanes.
2DEPH detection limit.
                                       5-18

-------
In addition to chemical stressors, the pathogenic protozoans Cryptosporidium parvum
and Giardia lamblia were selected for evaluation of biological stressors that may be
present in reclaimed water (York et al., 2002).

Florida's reuse rules have required monitoring for pathogenic protozoans since 1999.
Results of monitoring through September 2001 were reviewed by York et al. (2002).
Based on 48 observations, Cryptosporidium was detected in 23% of observations, with
8.3 % (3 observations) having more than 5 oocysts per 100 L. Giardia was detected in
58% of observations, with 46% of observations having more than 5 cysts per 100 L.
Although there are no specific reclaimed water standards for pathogenic protozoans, the
Florida DEP encourages improvements in the filtration process at facilities where greater
than 5.8 Cryptosporidium oocysts or cysts per 100 L are detected or greater than 1.4
Giardia cysts are found per 100 L (York et al., 2002).

5.6.3  Evaluation of Receptors and Assessment Endpoints

Based on required treatment levels and review of data from wastewater treatment
facilities utilizing aquifer recharge for wastewater management, representative
concentrations of chemical stressors were selected. These stressor concentrations were
used in fate and transport analyses based on travel distances of 200 feet, 500 feet, and 0.5
mile (2,640 feet), which were selected based on required setback distances and reporting
requirements. The procedures described in section 4.3 for fate and transport of stressors
in effluent injected to deep wells were applied to aquifer recharge. Referenced soil
sorption coefficients and half-lives for representative stressors used in chapter 4 were
used in this analysis to calculate attenuation of stressors during transport. Results of the
fate and transport analysis are presented in Table 5-5.
                                       5-19

-------
Table 5-5.   Contaminant Transport and Fate in the Surficial Aquifer

Chloroform (ug/L)
Arsenic (mg/L)
Di(2-ethylhexyl)
Phthalate (DEPH)
(WB/L)
Nitrate
(mg/L)
Dade County
(effluent travels 200 feet in 0.11 years; 500 feet, 0.28 years; 2,640 feet in 1.47 years)
Contaminant
travel time
Concentration
at injection
Concentration
at 200 feet
Concentration
at 500 feet
Concentration
at 2,640 feet
MCL
For 200 ft., 0 yrs.
For 500 ft., 0 yrs.
For 2,640 ft., 2 yrs.
7.18
7.06
6.88
5.73
80 (as trihalomethane)
For 200 ft., 0 yrs.
For 500 ft., 0 yrs.
For 2,640 ft., 2 yrs.
0.01
0.01
0.01
0.01
0.05
For 200 ft., 0 yrs.
For 500 ft., 0 yrs.
For 2,640 ft., 2 yrs.
5.00
4.56
3.97
1.48
6
N/A
N/A
0.64
0.64
0.64
10
Brevard County
(effluent travels 200 feet in 3.03 years; 500 feet, 7.58 years; 2,640 feet in 40.01 years)
Contaminant
travel time
Concentration
at injection
Concentration
at 200 feet
Concentration
at 500 feet
Concentration
at 2,640 feet
MCL
For 200 ft., 3 yrs.
For 500 ft., 8 yrs.
For 2,640 ft., 43 yrs.
230
146
73.7
0.6
80 (as trihalomethane)
For 200 ft., 3 yrs.
For 500 ft., 9 yrs.
For 2,640 ft., 45 yrs.
0.005
0.005
0.005
0.005
0.05
For 200 ft., 4yrs.
For 500 ft., 9 yrs.
For 2,640 ft., 48 yrs.
5.00
0.5
0.0
0.0
6
N/A
9.60
9.60
9.60
9.60
10
Pinellas County
(effluent travels 200 feet in 5.85 years; 500 feet, 14.63 years; 2,640 feet in 77.26 years)
Contaminant
travel time
Concentration
at injection
Concentration
at 200 feet
Concentration
at 500 feet
Concentration
at 2,640 feet
MCL
For 200 ft., 6.5 yrs.
For 500 ft., 16.3 yrs.
For 2,640 ft., 86.1 yrs.
6.7
2.68
0.68
0.00
80 (as trihalomethane)
For 200 ft., 7.12 yrs.
For 500 ft., 17.80 yrs.
For 2,640 ft., 93.97 yrs.
0.003
0.003
0.003
0.003
0.05
For 200 ft., 9.9yrs.
For 500 ft., 19.8 yrs.
For 2,640 ft., 104.6 yrs.
1.25
0.0 1
0.00
0.00
6
N/A
0.28
0.28
0.28
0.28
10
                                   5-20

-------
 Dilution and dispersion of stressors in groundwater were not considered in this analysis.
 These groundwater processes could result in lower concentrations at the 1,000-foot
 distance. Local hydrologic conditions may result in longer or shorter travel times.

 The shortest estimated travel times for effluent to reach receptor wells in the surflcial
 aquifer were in Dade County, where effluent travel times to reach wells at 200 feet, 500
 feet, and 2,640 feet were 0.11, 0.28, and 1.47 years, respectively. Such short travel times
 pose relatively higher risks than longer travel times found elsewhere in South Florida.
 However, because concentrations of representative chemical stressors in discharged
 effluent were below their respective drinking-water MCLs, the final concentrations of
 representative stressors at the receptor wells were also below MCLs. Therefore the
 human health risks do not appear to be significant for these stressors and these travel
 times.

 In Dade County, some stressors (for example, chloroform, DEPH) underwent further
 reduction as they traveled in the migrating effluent and decreased in concentration during
 their migration. However, the reduction amounts to less than a full order of magnitude
 reduction. Some other stressors (for example, arsenic, nitrate) did not undergo any
 decrease in concentration as they traveled through the shallow aquifer.

 In Brevard County, estimated travel times for effluent in  groundwater were intermediate
 in value. Effluent travel times to  reach 200, 500, or 2,640 feet were 3.03 years, 7.58
 years, and 40.01 years, respectively. For chloroform, effluent quality was elevated at
 injection (230 ug/L), but reduced to below the MCL at 500 feet. Like Dade County, final
 concentrations of all  stressors, whether nonconservative or conservative, were below their
 MCLs. The  modeled final concentration of one stressor, DEPH, fell to 0.00 at a distance
 of 500 feet,  after an estimated travel time of 9 years. Again, like Dade County, the human
 health risks  do not appear to be significant for these stressors and travel times.

 The longest  estimated travel times for effluent were found in Pinellas County. Estimated
 effluent travel times to reach 200, 500, and 2,640 feet were 5.85, 14.63, and 77.26 years,
 respectively. Initial concentrations of all stressors evaluated were below MCLs. The
 modeled final concentration  of chloroform fell to 0.00 at  a distance of 2,640 feet and a
 travel time of 86 years. The modeled final concentration of DEPH fell to 0.00 at a
 distance of 500 feet and a travel time of 19.8 years. Long travel times represent the
 lowest risk.  Again, like Dade and Brevard counties, there do not appear to be any human
 health risks for the compounds and substances regulated.

 Because reclaimed water treatment involves both basic disinfection and high-level
 disinfection  using chlorine, which effectively inactivates  most viruses and bacteria,
 reclaimed wastewater does not appear to pose any significant human health risk in terms
 of pathogenic bacteria or viruses (York et al., 2002).

 However, pathogenic protozoans that are not inactivated by chlorine may pose concerns,
particularly if reclaimed water is  not filtered adequately. Pathogenic protozoans such as
 Cryptosporidum parvum and Giardia lamblia oocysts may be capable of surviving for
                                       5-21

-------
relatively long periods of time in groundwater and surface water, based on laboratory
studies (There are very few in situ studies of oocyst inactivation). The most complete
review of survival of Cryptosporidum is that by Walker et al. (1998). This review
describes studies by Mawdsley et al. (1996a), who concluded that runoff contaminated
with oocysts posed a more significant threat to water quality than infiltration through the
soil profile, because of straining that tends to slow the transport of microorganisms
(McDonald and Kay, 1981). For these reasons, the Florida DEP recommends that
reclaimed wastewater should not contain more than 5.8 Cryptosporidium oocysts per 100
L or more than 1.4 Giardia cysts per 100 L (York et al., 2002). However, this is not yet a
regulatory requirement.

Cryptosporidium and Giardia also occur in groundwater and surface water in South
Florida (Rose et al., 2001; York et. al., 2002). The potential for aquifer recharge practices
to remobilize Cryptosporidium or Giardia cysts derived from other sources cannot be
evaluated hi this study because of the lack of information concerning site-specific
monitoring for pathogenic protozoans.

In summary, pathogenic protozoans that are not removed by chlorination pose the highest
health risks associated with this wastewater management option. However, it should be
pointed out that pathogenic protozoans are widespread in many natural surface water
bodies and in groundwater, from a variety of sources (agricultural runoff, domestic
animals, and, in particular, calves) (York et al., 2002; Walker et al.,  1998). These
concentrations in natural surface waters frequently exceed the amounts typically found in
reclaimed water (see Table 5-6).

Other chemical constituents of treated reclaimed wastewater appear to generally meet or
are lower than drinking-water standards.

Concentrations of nitrate and other nutrients that may remain in reclaimed water even
after removal of nitrogen may pose ecological concerns, because most natural aquatic
systems do not contain nitrate concentrations above the range from a few tenths of a ppm
to several ppm
                                      5-22

-------
 Table 5-6.     Comparison of Cryptosporidium Concentrations in the Environment
Water Type (and
Location)
Reclaimed water (St.
Petersburg)1
Phillippi Creek (FL)2
Five streams (FL)2
Sarasota Bay (FL)2
Tampa Bypass Canal (FL)3
Filtered drinking water4
Treated drinking water5
Surface-water supplies for
drinking-water plants5
Groundwaters6
Springs7
Lakes (pristine)7
Rivers (pristine)7
Surface waters (all
categories)7
Irrigation canais (AZ)8
Rivers in protected
watershed9
Average
(oocysts/100 L)
0.75
16
6.6
ND
3.1
1.52
3.3
240
41
4
9.3
29
43
555,000
2
Range
(oocysts/100 L)
ND^5.35
ND-158
ND-157
ND
ND-11
ND-48
ND-57
ND- 6,510


ND-307
ND - 24,000
ND - 29,000
530,000-580,000
ND-13
Notes
12 samples
16 samples from urban stream in
Sarasota
24 samples near Sarasota
4 samples from high-quality
estuary
7 samples
66 water-treatment plants in 14
states and 1 Canadian province
(85 samples)
1991-1993, 262 samples at 72
water plants
1991-1993, 262 samples at 72
water plants
74 samples
7 samples
34 samples
59 samples
181 samples in 17 states
2 samples
6 samples, western United States
'Rose and Carnahan, 1992.
2Rose and Lipp, 1997.
3Rose, 1993.
4LeChevallieretal., 1991.
3LeChevallier and Norton, 1995.
'Rose, 1997.
7Roseetal., 1991.
8Madore et al., 1987.
^ose, 1988.
ND = nondetectible
Source: Florida DEP, 1998.
                                           5-23

-------
5.7    Final Conceptual Model of Probable Risk

A final conceptual model of probable risk was developed as described below.

Aquifer recharge is broadly defined in this risk assessment as the replenishment or
recharge of a groundwater aquifer through a variety of application methods, including
rapid-rate land application, slow-rate land application, irrigation, and discharge to
wetlands that are hydrologically connected to groundwater. The aquifers of concern in
South Florida are the Biscayne and surficial aquifers, which are highly permeable and are
susceptible to contamination from a large variety of point and nonpoint sources. In South
Florida, the leading use of reclaimed wastewater is for irrigation of public-access areas
(158.24 mgd), followed by industrial uses (59.1 mgd), groundwater recharge (31.72
mgd), irrigation of restricted access areas (27.5 mgd), and discharge to wetland systems
(10.44 mgd).

Aquifer recharge using wastewater treated to reclaimed-water standards is called reuse in
the state of Florida and is regulated under Florida's reuse regulations. Beneficial uses of
reclaimed water includes aquifer recharge to restore or maintain aquifers, creation or
restoration of wetlands that have been adversely affected by human activities, and
creation of barriers to saltwater intrusion in coastal areas where withdrawal of fresh
groundwater has exceeded natural recharge rates. Beneficial uses also include the use of
reclaimed water for irrigation, which helps to conserve high-quality drinking-water
resources.

Although ASR can be conducted with reclaimed water, most ASR being discussed in
Florida involves the injection of high-quality water into aquifers for storage and later
retrieval. Therefore, ASR is not considered in this risk assessment.

Reuse regulations require that reclaimed wastewater be treated with secondary treatment
with basic disinfection if reclaimed water is intended for use in restricted-access
locations. In public-access areas, slow-rate application systems must use wastewater
treated to secondary levels with high-level  disinfection, at a minimum. Nitrification,
which helps to remove nitrogen from the wastewater, generally ensures that drinking-
water standards for nitrogen are met. Disinfection with chlorine, particularly high-level
disinfection, is highly effective at inactivating viruses and bacteria. Monitoring for fecal
coliforms as an indicator of wastewater pathogens is required in treatment wetlands.

Filtration, which is required to reduce  concentrations of total suspended solids, also
reduces concentrations of pathogenic oocyst-forming protozoans, such as
Cryptosporidium parvum and Giardia lamblia. Although there are no numerical water-
quality standards regulating the concentrations of pathogenic protozoans in treated
wastewater, the Florida DEP recommends that no more than 5.8 Cryptosporidium oocysts
per 100 L and no more than 1.4 Giardia cysts per 100 L be allowed in reclaimed water.
Filtration is the preferred method of removing pathogenic protozoans, although the DEP
has found that filtration is not always effective (York et al, 2002).
                                       5-24

-------
 Reuse regulations also require setbacks for aquifer recharge from public water-supply
 wells, surface-water supplies, and public-access areas. These setback distances vary,
 depending on the particular reuse option, from 75 feet to 500 feet or more. Such setbacks
 help to protect public water supplies from potential contaminants in surface-water runoff
 and in groundwater.

 Figure 5-1 presents the generic conceptual model for the aquifer recharge wastewater
 management option. The primary source of potential stressors was defined as rapid-rate
 land application systems using reclaimed wastewater. In this conceptual model, reclaimed
 water is discharged to RIBs located directly above surficial aquifers. RIBs are generally
 located tens of feet (not hundreds or thousands of feet) above the water table. The
 principal exposure pathway in aquifer recharge was postulated to be migration of
 reclaimed water from the discharge point to the USDW. Groundwater may also carry
 reclaimed water constituents to areas where groundwater discharges to surface water,
 potentially affecting ecological receptors.

 This option-specific risk assessment used an analysis of fate and transport of discharged
 reclaimed wastewater and representative chemical and microbiological constituents of
 wastewater, applied to rapid-rate land application. The fate-and-transport analysis was
 based on an analysis of the movement of discharged effluent in groundwater, estimation
 of the time of travel needed for effluent water to reach a drinking-water receptor such as a
 water supply well, and estimation of the fate of chemical constituents within the time of
 travel, using half-lives of chemical compounds and other characteristics. The approach
 used is the same as that used in chapter 4 for the fate-and-transport analysis of effluent
 discharged from Class I deep injection wells, except that the discharged effluent in
 aquifer recharge is moving down towards the aquifer rather than migrating upward
 towards the aquifer. Porous media flow is assumed for aquifer recharge.

 The analysis of estimated travel times for rapid-rate land application indicated that Dade
 County may have the  shortest travel times for effluent and hence the highest risk of
 contaminating the aquifer. These travel times ranged from 0.11 years to 0.28 years and
 1.47 years for effluent to travel 200 feet, 500 feet, and 0.5 miles, respectively. However,
 the fact that reclaimed water is treated to relatively high standards, and because
 attenuation further reduces the concentrations of constituents along the path of travel,
 means that the actual risk to human health is most likely nonexistent to very low.  The
 only possible exception is where filtration is not done or is ineffective at removing
 pathogenic protozoans, as described below).

 In Brevard County, effluent travel times ranged from 3.03 years to 7.58 years to over 40
 years  for effluent to travel 200 feet, 500 feet, and 0.5 miles, respectively. As  in Dade
 County, concentrations of chemical constituents in reclaimed water meet drinking-water
 standards before discharge. Concentrations of nonconservative constituents decrease
 further over this time period, while concentrations of conservative constituents remain the
 same  over time. For these reasons, aquifer recharge using reclaimed water is not expected
to pose significant human health risks in Brevard County, with the possible exception of
pathogenic protozoans, as described below.
                                       5-25

-------
Pinellas County has the longest estimated effluent travel times and hence the lowest
relative risk of the three areas evaluated. Estimated effluent travel were 5.85 years, 14.63
years, and 77.26 years to travel 200 feet, 500 feet, and 0.5 mile, respectively. Initial
concentrations of all wastewater constituents were below their MCLs, and the final
concentrations of conservative constituents remained the same. Concentrations of
nonconservative constituents decreased even further over these time periods. Again, there
do not appear to be any human health risks posed by the chemical constituents of
reclaimed water.

Of all possible wastewater constituents remaining after treatment, oocyst-forming
pathogenic protozans, such as Giardia lamblia and Cryptosporidium parvum, probably
pose the greatest risks to human health, particularly if filtration is not effective at
removing these oocyst-forming protozoans below DEP-recommended levels of 1.4 and
5.8 oocysts per 100  L, respectively. However, even if filtration is not this effective, the
risks would be roughly comparable to ingesting untreated water from other natural
surface-water sources that are considered pristine or relatively unimpacted by human
activities or animal wastes.

Since reclaimed water may contain higher concentrations of nutrients than those found in
ambient surface waters, there could potentially be ecological effects in nearby surface
water bodies that receive reclaimed water. Chapter 7 provides a full discussion of water-
quality criteria for unimpacted natural surface  water bodies.

5.8    Potential Effects of Data Gaps

Because of the variable nature of geology and  soils across the study area and the relative
lack of site-specific  information regarding groundwater flow and times of travel, actual
conditions may differ from those expected. These differences may affect the risk
assessment of the aquifer recharge methods in important ways. Data gaps occur in the
groundwater information used for modeling fate and transport and in data on the water
quality of discharged effluent and groundwater monitoring. Some of the potential effects
of such data gaps  are the following:

   •   Local variations in geologic and hydrologic conditions may result in differences
       in travel time from recharge locations to receptor wells and surface water bodies.
   •   Because of the lack of monitoring wells in the Biscayne Aquifer, there is no
       ability to predict or foresee potential adverse effects on public water supplies,
       whether risks arise from this wastewater management options or other activities.
   •   If hydrologic connections between groundwater and surface water bodies exist,
       then that provides another exposure or  transport pathway  whereby surface waters
       may be affected by aquifer recharge. The information reviewed in this study did
       not permit such detailed conclusions to be made, and this  is an aspect of aquifer
       recharge that should be investigated on a site-specific basis. Site-specific
       monitoring of movement and water quality of groundwater and surface water
       should be used to determine whether there is a direct hydrologic connection
                                       5-26

-------
between the groundwater that receives discharged reclaimed water and surface
water bodies or wetlands.
The fate and transport of preexisting contaminants in groundwater and soils
beneath the recharge site are unknown. There is a possibility that such preexisting
contaminants may become remobilized by application of reclaimed water from
above, but there is no specific monitoring information to indicate whether this
might actually occur.
                               5-27

-------
REFERENCES

Adams K. 1992. A three dimensional finite difference flow model of the Surficial Aquifer
       In Martin County, Florida. Technical Publication DRE-310. West Palm Beach
       (FL): South Florida Water Management District.

[ATSDR] Agency for Toxic Substances and Disease Registry. 1993. Public Health
       Statement for Di (2-ethylhexyl) phthalate.

Barr GL. 1996. Hydrogeology of the surflcial and intermediate aquifer systems in
       Sarasota and adjacent counties, Florida. USGS WRI 96-4063. Washington (DC):
       USGS.

[FDEP] Florida Department of Environmental Protection. 1998. Risk Impact Statement:
       Phase II Revisions to Chapter 62-610. FAC Docket No. 95-08R.

	. 2001a. 2000 Reuse Inventory. Talahassee (FL): FDEP.
          . 2001b. Reuse Facts. Internet: http://www.dep.state.fl.us/water/reuse/
       facts.htm.
          . 2001c. Uses of Reclaimed Water. Internet: http://www.dep.state.fl.us/water/
       reuse/uses.htm.

      	. 200Id. Domestic Waste\vater to Wetlands Program Wakodahatchee
       Wetland. Internet: http://www.dep.state.fl.us/water/wastewater/dom/wetwako.htm

      	, 2002. Use of Reclaimed Water on Golf Courses. Internet:
       http://www.dep.state.fl.us/water/reuse/docs/pdf/golfcourse.pdf.

      	. 200le. Florida's Domestic Wastewater to Wetlands Rule. Internet:
       http://www.dep.state.fl.us./water/wastewater/dom/wetrule.htm. Accessed on 18
       October 2001.
Howard PH. 1991. Handbook of Environmental Degradation Rates. Boca Raton (FL):
       CRC Press LLC.

LeChevallier MW and Norton WD. 1995. Giardia and Cryptosporidium in raw and
       finished water. Journal of the American  Waterworks Association, 87: 54.

LeChevallier MW, Norton WD, and Lee RG. 1991. Giardia and Cryptosporidium spp. in
       filtered drinking water supplies. Applied and Environmental Microbiology. 57:
       2617.

Lukasiewicz J and Adams KS. 1996. Hydrogeologic data and information collected from
       the Surficial and Floridian Aquifer Systems, Upper East Coast Planning Area.
                                     5-28

-------
       Technical Publication WRE #337. West Palm Beach (FL): South Florida Water
       Management District.

Madore MS, Rose JB, Arrowood MJ, and Sterling CR. 1987. Occurrence of
       Cryptosporidium oocysts in sewage effluents and selected surface waters. Journal
       ofParasitology. 73: 702.

Maliva RG and Walker CW. 1998. Hydrogeology of deep-well disposal of liquid wastes
       in Southwestern Florida, USA. Hydrogeology Journal. 6(4):538-548.

Mawdsley JL, Brooks AE, and Merry RJ. 1996a. Movement of the protozoan pathogen
       Cryptosporidium parvum through three contrasting soil types. Biology of Fertile
Mawdsley JL, Brooks AE, Merry RJ, and Pain BF. 1996b. Use of a novel soil tilting table
       apparatus to demonstrate the horizontal and vertical movement of the protozoan
       pathogen Cryptosporidium parvum in soi. Biology of Fertile Soils, 23: 215-220.

McDonald A and Kay D. 1981. Enteric bacterial concentrations in reservoir feeder
       streams: Baseflow characteristics and response to hydrograph events. Water
       Research. 15:961-968.

Meyer FW. 1989. Hydrogeology, ground water movement, and subsurface storage in the
       Floridan Aquifer System in Southern Florida. USGS Professional Paper 1403-G.
       Washington (DC): USGS.

Miller JA. 1997. Hydrogeology of Florida. In: The Geology of Florida. Randazzo AF and
       Jones DS, eds. Gainesville: University Press of Florida.

Randazzo AF and Jones DS. 1997. The Geology of Florida. Gainesville: University Press
       of Florida.

Reese RS and Cunningham KJ. 2000. Hydrogeology of the Gray Limestone Aquifer in
       Southern Florida. USGS WRI 99-4213. Washington (DC): USGS.

Reese RS and Memburg SJ. 1999. Hydrogeology of the Gray Limestone Aquifer in
       Southern Florida. WRI 99-4213. Washington (DC): USGS.

Rose JB. 1997. Health considerations in reuse. Orlando (FL): Water Reuse Workshop,
       Florida Engineering Society.

_ . 1993. Tampa Water Resource Recovery Pilot Project Microbiological
       Evaluation. In: Tampa Water Resource Recovery Project Pilot Studies. Final
       report to the City of Tampa. Edgewood, (CO): CH2M Hill.
                                     5-29

-------
          . 1988. Occurrence and significance of Cryptosporidium in water. Journal
       American Waterworks Association, 80: 53.

Rose JB, Gerba CP, and Jakubowski W. 1991. Survey of potable water supplies for
       Cryptosporidium and Giardia. Environmental Science and Technology. 25: 1393.

Rose JB and Carnahan RP. 1992. Pathogen Removal by Full Scale Wastewater
       Treatment. A report to the Florida Department of Environmental Protection.
       Tampa (FL): University of South Florida.

Rose JB and Lipp EK. 1997. A study on the presence of human viruses in surface waters
       ofSarasota County. St. Petersburg (FL): University of South Florida.

Rose BR, Quintero-Bentancourt W, Jarrel 3, Lipp E, Farrah S, Lukasik G, and Scott T.
       2001. Deep Injection Monitoring Well: Water Quality Monitoring Report.
       Received by Florida DEP, Southwest District, Tampa.

[USGS] United State Geological Survey. 2000. Hydrologic Atlas 730-G Biscayne
       Aquifer. In: Ground Water Atlas of the United States. Washington (DC): USGS.

Walker MJ, Montemagno CD, and Jenkins MB. 1998. Source water assessment and
       nonpoint sources of acutely toxic contaminants: a review of research related to
       survival and transport of Cryptosporidium parvum. Water Resources Research.
       34: 3383-3392.

York DW, Menendez P, and Walker-Coleman L. 2002. Pathogens in reclaimed water:
       The Florida Experience.  2002 Water Sources Conference.
                                     5-30

-------
6.0    OCEAN OUTFALLS

In this chapter, the potential ecological and human health risks associated with
management of treated municipal wastewater via discharge to ocean outfalls are
described and evaluated.

6.1    Definition of Ocean Outfalls

Management of treated municipal wastewater using ocean outfalls involves discharging
treated wastewater directly to the ocean via outfall pipes. Wastewater receives secondary
treatment, including basic disinfection with chlorine.

6.2    Capacity and Use in South Florida

South Florida has six publicly owned wastewater treatment facilities that discharge
treated municipal wastewater to the ocean. These six facilities are the Miami-Dade
Central District, Miami-Dade North District, City of Hollywood, Broward County, Boca
Raton, and Delray Beach facilities (Figure 6-1). All six facilities discharge secondary-
treated wastewater effluent into the western portion of the north-flowing Florida Current.
Table 6-1 displays the distance from shore and the depth at which treated wastewater is
discharged from these six facilities.

Table 6-1.    Characteristics of Southeast Florida Ocean Outfalls
Parameter
Approximate
volume discharged,
million gallons per
day (mgd)
Discharge depth,
meters (m)
Distance offshore
(mi)
Number of ports
Diameter of ports
(m)
Port orientation
Miami-
Dade
Central
District
133* (both
Central and
North)
28.2
3.56
5
1.22
Vertical
Miami-
Dade
North
District
100*
29.0
2.08
12
0.61
Horizontal
City of
Hollywood
42*
28.5
1.90
1
1.52
Horizontal
Broward
County
66* - 80**
32.5
1.32
1
1.37
Horizontal
Delray
Beach
16.55**
29
0.99
1
0.76
Horizontal
Boca
Raton
13.66**
27.3
0.94
1
0.91
Up 45
degrees
from
horizontal
*Source: NOAA. 2002a
**Source: Marella, 1999
Source: Hazen and Sawyer, 1994.
                                       6-1

-------
                                  Delray Beach
                             1C /* Boca Ration
                                  Broward
                              1 L_, Hollywood
                                                                 Source: Hazen and Sawyer, 1994
Figure 6-1.  locations of Ocean Outfalls in  outhern Florida
                                       6-2

-------
 The two outfalls with the highest flow rates (Miami-Dade North and Miami-Dade
 Central) have multiport diffusers, while the other four outfalls with lower flow rates
 outfalls discharge through single ports. The Miami-Dade Central Outfall discharges
 beyond the 3-mile state jurisdiction into federal waters. All six treatment facilities
 provide secondary treatment and basic disinfection, using chlorine.

 The physical behavior of effluent plumes in the ocean is well understood, based on
 studies at a number of ocean outfalls worldwide (Wood et al, 1993). The physical
 behavior of the effluent plumes from the Florida ocean outfalls has also been extensively
 studied. When treated wastewater is discharged into the ocean from an outfall pipe, a
 plume of effluent is formed that tends to rise in seawater because the effluent is less
 saline and more buoyant than seawater. The speed and orientation of the ocean currents
 are the primary factors  governing plume dispersion.

 Figure 6-2 illustrates the behavior of an effluent plume discharging into the Florida
 Current. Water column stratification; determined by water inputs, precipitation,
 temperature, and advection caused by winds (Wood et al., 1993), may also play a role.
 For example, the thermocline, (a horizontal plane at which a distinct change in water
 temperature occurs) may present some barrier to mixing. Off the east coast of Florida,
 although the plume feature may remain relatively intact near the outfall pipe, the Florida
 Current rapidly disperses the effluent water and constituents, diluting it and mixing it
 with the surrounding water.

 When evaluating the potential impacts of the southeast Florida ocean outfall discharges
 on the marine environment, South Florida wastewater utilities and regulatory agencies
 recognized that additional information was needed in order to develop conditions for
 outfall permitting. Understanding how discharged effluent undergoes dispersion, mixing,
 and dilution in the ocean is particularly important for risk assessment of ocean outfalls.
 While earlier studies of circulation and mixing provided critical knowledge concerning
 the large-scale behavior of the Florida  Current, they did not provide the extensive amount
 of detail needed to thoroughly understand and predict effluent dispersion and dilution at
 all six of the outfall sites.

 The Southeast Florida Outfall Experiment (SEFLOE) studies were initiated in the early
 1990s. The SEFLOE studies were undertaken by the wastewater treatment facilities,
 working closely with the Ocean Acoustics Division of the Atlantic Oceanographic and
 Meteorological Laboratory of the National  Oceanic and Atmospheric Administration
 (NOAA), the Florida Department of Environmental  Protection (DEP), and the U.S.
 Environmental Protection Agency (EPA). These studies provide a significant amount of
 information concerning the mixing, dispersion, and dilution of wastewater plumes
 originating from these six ocean outfalls, the environmental characteristics of the outfall
 sites, and the chemical characteristics of both treated wastewater and receiving waters.
 This information was used to develop recommendations for the width of mixing zones
that are required under state regulations. These mixing zones are necessary to allow
 discharged effluent to meet water-quality standards through dispersion and dilution.
                                       6-3

-------
                                               Surfacing
                                                 Plume
En
Pi
Jof
)e
Momentum
Displacement

\™>
Current
Displacement
f-
                400m
              Regulatory
              Mixing Zone
                  i
Zone of Initial       i
                                                             Dilution Boundary
     Discharge Depth
        27-32 m
                                                                            Source: Hazen and Sawyer, J99
-------
The SEFLOE studies began with several physical oceanographic studies of effluent
plume dispersion, mixing, and dilution. Effluent plumes were tracked and monitored
using acoustical backscatter techniques, in one of the most extensive applications of
acoustics to wastewater effluent studies in the United States (Proni, 2000; Proni and
Williams, 1997; Proni et al.,  1995; Williams and Proni, 1994; Proni and Dammann,
1989). Mixing zones for the southeast Florida outfall plumes were modeled using three
different models that incorporated field data:  CORMIX, PLUMES, and OMZA. All three
models predicted realistic initial dilutions for outfalls with only minor exceptions (Huang
et al., 1998). The results of these studies were used to develop wastewater treatment
recommendations aimed at meeting water-quality standards within a 400-m-radius
mixing zone.

Biotoxicity testing of secondary-treated wastewater and diluted effluent were conducted
as well (Commons et al., 1994a). Many of these studies are summarized in the
comprehensive report assembled by Hazen and Sawyer (1994). According to these
studies, toxicity testing on marine organisms indicated that diluted effluent did not cause
toxic effects in marine test organisms.

The initial SEFLOE I study focused on characterizing initial and farfield dilution
properties of the ocean outfall plumes using acoustical backscatter techniques,
determining the nutrient and bacterial content of the effluent and receiving waters,
characterizing marine conditions, and evaluating concerns about nondegradable
substances in the discharged treated effluent.

The SEFLOE II study continued to improve understanding of year-round physical
oceanographic conditions at four of the outfalls, defining rapid dilution and mixing zones
through modeling of near-field and farfield conditions. SEFLOE II also continued
monitoring of nutrient concentrations in the effluent plumes. The SEFLOE II study
examined the toxic characteristics of the receiving water/effluent mixture with and
without chlorination, using bioassay techniques. Finally, the study examined whether the
diluted wastewater met water-quality standards for priority pollutants, bacteria, and oil
and grease.

6.3    Environment into Which Treated Wastewater is Discharged

Two major current systems dominate marine circulation along the western and eastern
coasts of South Florida: the Loop Current, which flows out of the Gulf of Mexico in a
southeasterly direction, passing the Dry Tortugas, and the Florida Current, which is the
extension of the Loop Current as it flows east towards the Florida Keys and then north
along the east coast of South Florida, until it joins the northward-flowing  Gulf Stream
(Lee et al., 1995).  Smaller countercurrents, flowing west from the Florida Keys and
Florida Bay, and southerly currents from the southwest Florida shelf meet the Loop
Current in the area near the Dry Tortugas to form the Tortugas Gyre (Lee et al.,  1995),
another major eddy system. The Pourtales  Gyre exists to the east of the Tortugas Gyre.
                                       6-5

-------
Understanding the movements of the Florida Current, particularly in its northern reaches
off the east coast of Florida, is important for this risk analysis because the six ocean
outfalls located in southeast Florida discharge treated wastewater effluent to the Florida
Current. The Florida Current is made up in roughly equal parts of waters originating in
the south Atlantic and north Atlantic subtropical gyres, connecting the Loop Current's
flow out of the eastern Gulf of Mexico with the north Atlantic or Gulf Stream (Schmitz
and Richardson, 1991; Lee et al., 1995). In the southern Straits of Florida, the presence of
at least two gyre systems and variations in the flow of the Loop Current can cause the
Florida Current to meander before it turns northward in the Santaren Channel (Lee et al.,
1995).

As the Florida Current travels northward off the east coast of Florida, spin-off eddies are
created (Lee, 1975; Lee et al., 1995). These eddies include several components, including
northerly flows associated with western meanders of the Florida Current, southerly flows,
and rotary flows, composed of groups of rotations interspersed between northerly and
southerly flows. Rotary flow involves water flows that move in a roughly circular
manner, much as a whirlpool does. As the Florida Current moves north to join the Gulf
Stream, these rotary flows also move, or are translated, in a northerly direction. These
eddy and rotary flow systems were studied extensively during SEFLOE. Figure 6-3, from
Hazen and Sawyer (1994), depicts the three different current regimes and their circulation
characteristics, as the current moves or translates from time /; to a later time (3.

The eddies and  rotary  flows occurring along the western boundary of the Florida Current
impart a variability to  the circulation system that is important for understanding potential
ecological or human health risks that may be associated with ocean outfalls in this area.
The variability of the Florida Current's western boundary is important because the
Florida Current represents a major source of nutrients for primary productivity in the
area. Incursions of the Florida Current onto the continental shelf are reflected in enhanced
phytoplankton and zooplankton growth from Cape Canaveral to Cape Hatteras (Atkinson,
1985). Shorter incursions of Florida Current water onto the continental shelf, lasting days
to weeks, have been recorded from Miami to Pompano (Lee, 1975; Lee and Mayer,
1977).

6.4    Regulations and Requirements Concerning Ocean Outfalls

6.4.1   General Requirements

Ocean outfalls in South Florida are required to provide secondary treatment of municipal
wastewater and disinfection with the minimal amount of chlorine necessary to achieve
water-quality standards.  Overchlorination of wastewater containing organic materials can
result in creation of organochlorine compounds such as trihalomethanes, which are
associated with  human health risks.
                                       6-6

-------
                        (northerly flow)
                           Large scam
                            southerly,
                                       All three circulation features
                                       move in a northerly direction over time.
                                                                                          Source: Hazen and Sau/yer. 1994
Figure 6-3.  Girculation nharacteristics of the Destern Boundary Degion of the Florida aurrent.

-------
The federal Clean Water Act (33 USC 1251 et seq.) prohibits discharge of any waste to
any waters of a state unless the waste is first treated to protect the beneficial uses of such
water (see also Florida Administrative Code (FAC) 62-650). At a minimum, sewage
treatment plants discharging to the ocean or other surface waters must provide secondary
treatment in order to meet this pollution reduction standard.

The Florida Air and Water Pollution Control Act (Title 19, Chapter 403, Part I, Florida
Statutes) also prohibits discharge of any  untreated wastes to any waters of the state (FAC
62-650). In the state of Florida, waters used for recreation, propagation, and maintenance
of a healthy, well-balanced population offish and wildlife are classified as Class III
Waters (FAC 62-302.400(1)). In such waters, state regulations require that, prior to
discharge and after disinfection, wastewater effluent meet the most stringent of the
following two standards: either (1) effluent must not exceed 20 milligrams per liter
(mg/L) CBOD5 and 20 mg/L of total suspended solids (TSS), or (2) 90% of CBOD5 and
TSS must be removed from the wastewater influent (FAC 62-600.420(1 )(a) and 62-
600.420(b)(l)). All wastewater treatment facilities, whether new or existing, must
achieve at a minimum the specified effluent limitations (20 mg/L) and must also maintain
safe pH and disinfect (FAC 62-600.420(b)(2)).  The Florida DEP has also established
technology-based effluent limits (TBELs), which include requirements for secondary
treatment, pH levels, and disinfection.

6.4.2   Secondary Treatment of Wastewater

Secondary treatment for the state of Florida removes biodegradable organic matter and
suspended solids and includes basic disinfection. Secondary treatment plants are designed
to produce effluents that  contain no more than 30 mg/L CBODs and 30 mg/L TSS. The
plants must also remove  85% of CBODg and TSS from wastewater. State regulations
require that, after basic disinfection, secondary-treated wastewater cannot exceed 20
mg/L of CBOD5 and 20 mg/L of TSS or that 90% of CBOD5 and TSS must be removed
from the wastewater influent, whichever is more stringent (FAC 62-600.420(l)(a)). The
effluent pH, after disinfection, must be within the range of 6.0 to 8.5 (FAC 62-600.420).

6.4.3   Basic Disinfection

Basic disinfection of wastewater must result in effluent with not more than 200 fecal
coliforms per 100 milliliters (mL), at a minimum (FAC 62-600.445, 62-600.520(2), 62-
600.420). When chlorine is used as the disinfection agent, the facility must provide for
rapid  and uniform mixing, with a total chlorine  residual of at least 0.5 mg/L after at least
15 minutes contact time at the peak hourly flow (FAC 62-600.440(4)). In addition,
wastewater must be disinfected so as to achieve Class III microbiological standards at the
edge of the mixing zone or the level of disinfection deemed appropriate (FAC 62-
600.520(2) and (3)). If the discharge is to Class III coastal waters, the disinfected effluent
cannot contain more than 20 mg/L CBODs and  20 mg/L TSS, or 90% of these pollutants
must be removed from the wastewater, whichever is more stringent. In addition to these
standards, bioassay toxicity tests must be conducted to ensure that aquatic organisms do
not experience toxic effects from the effluent.
                                      6-8

-------
6.4.4  Water Quality Standards for Receiving Waters

Section 403(c) of the Clean Water Act, Ocean Discharge Criteria, applies to point-source
discharges to ocean waters. Point-source discharges to ocean waters must not cause
unreasonable degradation of the marine environment. Standards for receiving waters are
generally more stringent than end-of-pipe limits, and thus there are regulations that
pertain to the water quality of the discharge at the end of the pipe, within the mixing
zone, and at the edge of the mixing zone. The Florida DEP has also established water-
quality-based effluent limits to carry out the goals of the Florida statute. These limits are
applied when additional treatment is necessary to ensure that the available assimilative
capacity of a water body will  be protected (FAC 62-650.)

Within the mixing  zone, the EPA addresses acute toxicity by establishing criteria for the
maximum concentrations (CMC). The CMC is approximately one-half of the acute
concentration of the parameter of interest for the most sensitive species. A facility can
meet these criteria  by any one of the four following methods:

    •  Demonstrate that the CMC level is not exceeded at the  end-of-pipe
    •  Provide rapid mixing with a high-velocity discharge so that the CMC is met a
       short distance from the outfall
    •  Meet the CMC within 10% of the distance to the edge of the mixing zone or 5
       times the concentration of the parameter in local waters (Florida DEP)
    •  Demonstrate that a drifting organism is not exposed to average concentrations
       exceeding the CMC for a 1-hour time interval.

The federal, state, and local regulations require compliance with surface-water quality
standards at the edge of the mixing zone. A mixing zone range is the distance needed for
the effluent plume  to become  sufficiently diluted. The dilution occurs when the effluent
plume mixes with ambient seawater to the point where the concentration of indicator
bacteria reaches Class III water quality standards. The FAC allows a maximum mixing
zone area of up to 502,655 square meters (m2) for open-ocean outfalls (FAC 62-
4.244(1 )(h)). Water quality must meet Class III microbiological standards at the edge of
the mixing zone, or the level of disinfection deemed appropriate, as described in Table 6-
2 (see FAC 62-4.244 regarding mixing zones and see 62-600.520(2)). Although the
mixing radius need not be circular in shape, the area required is equivalent to that of a
400-m-radius circle, which can be more easily visualized and incorporated into a
conceptual model.  The actual  mixing zone will never be exactly circular.
                                       6-9

-------
Table 6-2.  Federal and Florida Class III Water Quality Criteria and Guidance
            Values for Indicator Bacteria Groups
Group
Fecal coliform
Total coliform
Enter ococcus*
Monthly Geometric Mean
(colonies per 100 mL)
200
1,000
35
Percent
not more than 10%
over 400
not more than 20%
over 1,000
not more than 10%
over 70
Maximum Single Value
(colonies per 100 mL)
<800
<2,400
<140
*Guidance values
Source: Hazen and Sawyer, 1994.
6.5    Problem Formulation

In this section, general information concerning potential stressors, receptors, and
exposure pathways is used to develop a conceptual model that depicts potential risk that
may be associated with ocean outfalls. Section 6.6 presents an evaluation of actual risk.

6.5.1  Potential Stressors

Potential ecological stressors that may be present in secondary-treated wastewater include
the following:

       •   Nutrients (nitrogen, phosphorus, iron) that could promote primary
           productivity and growth of harmful algal blooms
       •   Metals
       •   Volatile organic compounds
       •   Synthetic organic compounds (for example, organochlorine compounds such
           as trihalomethanes and chlorinated hydrocarbons)
       •   Other substances suspected of causing adverse effects on aquatic organisms
           (for example, endocrine-disrupting compounds)
       •   Substances whose ecological and biological effects are not yet well studied
           (for example, detergents, surfactants).

Potential human  health stressors include the following:

       •   Pathogenic enteric microorganisms (bacteria, viruses, and protozoans)
           capable of surviving basic disinfection
       •   Metals
       •   Organic compounds
       •   Endocrine-disrupting compounds
       •   Nutrients such as nitrate and nitrite that can cause human health effects at
           higher concentrations.
                                       6-10

-------
Basic disinfection will deactivate most of the viruses and pathogens (see treatment
requirements, above), but will not deactivate protozoans such as Cryptosporidium or
Giardia, which must be filtered out.

6.5.1.1 Nutrients and Eutrophication

Nutrients act as potential stressors when they stimulate primary production that results in
eutrophication. In coastal waters such as those of southeast Florida, as in large areas of
the world's oceans, coastal, and estuarine waters, primary production is usually limited
by nitrogen (Dugdale, 1967; Ryther and Dunstan, 1971; Codispoti, 1989; Paerl, 1997).
However, phosphorus can be limiting under some conditions, particularly in coastal
waters where there may be varying  salinities. On geologic time scales, phosphorus is
believed to limit marine productivity (Howarth, 1988; Holland, 1978; Smith, 1984;
Codispoti, 1989; Ruttenberg, 1993). Some marine cyanobacteria, Sargasso Sea
phytoplankton, and some Caribbean macroalgae are phosphorus-limited (LaPointe, 1997;
Sellner, 1997; Cotner et al., 1997).

A recent National Academy review of the causes of eutrophication of coastal waters
found that nutrient overenrichment of coastal marine waters have resulted in the
following adverse effects (National Research Council, 2000):

    •   Increased primary productivity
    •   Increased oxygen demand and hypoxia
    •   Shifts in community structure caused by anoxia and hypoxia
    •   Changes in phytoplankton community structure
    •   Harmful algal blooms
    *   Degradation of seagrass and algal beds and formation of nuisance algal mats
    *   Coral reef destruction.

The National Research Council review concluded that, while nitrogen is important in
controlling primary production in coastal waters and phosphorus is important in fresh
water systems, both need to be  managed to avoid one or the other becoming the limiting
nutrient (National Research Council, 2000). The differences in causes of eutrophication
between fresh and marine ecosystems stem from a variety of ecological and
biogeochemical factors, including the relative inputs of nitrogen versus phosphorus
within the ecosystem and the extent to which nitrogen fixation can alleviate nitrogen
shortages. In addition, eutrophication of coastal systems is often accompanied by
decreased silica availability and increased iron availability, both of which may promote
the  formation of harmful algal blooms (National Research Council, 2000).

There are exceptions  to the general principle that nitrogen is limiting in coastal
ecosystems.  For instance, the Apalachicola estuarine system on the Gulf coast of Florida
appears to be phosphorus-limited (Myers and Iverson, 1981). Howarth (1988) and Billen
et al, (1991) postulate that this is related to the relatively high ratio of nitrogen to
phosphorus inputs. However, in this case, the ratio may also reflect the relatively small
amount of human disturbance in the watershed and the relatively low nutrient inputs
                                      6-11

-------
overall. Howarth et al. (1995) suggests that there is a tendency for estuaries to become
more nitrogen-limited as they become more affected by humans and as nutrient inputs
increase overall. This is because productivity is a function of the availability of nutrients
to phytoplankton.

In nearshore tropical marine systems, phosphorus appears to be more limiting for primary
production (Howarth et al., 1995), while the tropical open ocean is nitrogen-limited
(Corredor et al., 1999). Nutrient limitation switches seasonally between nitrogen and
phosphorus in some major estuaries such as the Chesapeake Bay (Malone et al., 1996)
and in portions of the Gulf of Mexico, including the so-called "dead zone" (Rabalais et
al., 1999).

There are approximately 300 species of algae known to produce "red tides," including
flagellates, dinoflagellates, diatoms, silicoflagellates, prymnesiopytes, and raphidophytes.
Of these 300 species, approximately 60 to  80 species are actually harmful or toxic as a
result of their biotoxins, nutritional unsuitability, and ability to cause physical damage or
anoxia, reduce irradiance, and so forth. (Smayda, 1997). In Florida, problematic harmful
algae bloom (HAB) species include Pfiesteria species, Cryptoperidiniopsoid^
Alexandrium monilatum, Chattonella subsalsa, Dinophysis spp., Gambierdiscus toxicus,
Gymnodinium pulchellum, Gyrodinium galatheanum, Gymnodinium breve, Karenia
brevis (said to be the most common cause of red tide on the Florida coast), Karenia
mikimotoi, and the benthic genus Prorocentrum spp. The Gulf coast of Florida has been
typically  more affected by HABs, particularly of Gymnodinium breve; often during the
summer and fall when seasonal changes in the wind and sea surface temperature occur
(FFWCC,2001).

Toxic symptoms of HABs can affect both humans and animals and include paralytic
shellfish poisoning (PSP), diarrheic shellfish poisoning (DSP), amnesic shellfish
poisoning (ASP), ciguatera fish poisoning (CFP), and neurotoxic shellfish poisoning
(NSP). The effects range from discomfort to incapacitation to mortality (FFWCC,
2002a).

Environmental changes that may stimulate HABs include a variety of physical, chemical,
and biological factors, such as climate change, increased pollution and nutrient inputs,
habitat degradation through dredging, resource harvesting and regulation of water flows,
and the failure of grazing organisms to control algal growth. The two primary algal
groups that produce blooms in response to nutrient inputs are the cyanobacteria and
macroalgae, as well as other species from different groups (NOAA, 2002b). Even
nontoxic  HABs  can disrupt other organisms through biofouling, clogging of gills, or
smothering of coral reefs and seagrass beds in South Florida (LaPointe, 1997).

HABs can also be caused by marine cyanobacteria, commonly called blue-green algae.
Marine cyanobacterial species responsible for HABs include only a few taxa, such as
Trichodesmium, Richelia, Nodularia, and Aphanizomenon. Trichodesmium^ which is
nitrogen-fixing,  is found in low- and mid-latitude oceans and seas of the Atlantic, Pacific,
and Indian oceans. Marine cyanobacterial blooms can occur in warm stratified areas in
                                      6-12

-------
the ocean and in embayments and estuaries where nitrogen concentrations are often low,
salinities are reduced, and where phosphorus becomes enriched through upwelling,
eddies, mixing, or other sources. Phosphorus limitation appears to be more important
than nitrogen limitation, since some of these species are nitrogen-fixing and inhabit
nitrogen-poor waters (Sellner, 1997).

Human and animal health can be affected by ingestion of the toxins created by
cyanobacteria such as Trichodesmium^ Nodularia and Aphanizomenon, as documented by
livestock, canine, and human cases (Sellner, 1997; Nehring, 1993; Edler et al., 1985).
Other adverse effects of Trichodesmium blooms include mortality of mice, brine shrimp,
and copepods; asphyxiation offish, crabs, and bivalves; retreat of zooplankton to deeper
waters free of the algae; and food-chain effects (reviewed in Sellner, 1997).

In Florida, extensive blooms of cyanobacteria, involving the cyanobacteria Lyngbya
majuscula, a species that occurs worldwide, were documented in Tampa Bay in 1999 and
from Sarasota Bay to Tampa Bay in 2000. Although this species is not toxic, it can
produce large slimy brown floating mats and emit a foul odor (FFWCC, 1999). The
causes of these blooms  are unknown, although they are not believed to be related to
sewage releases.

6.5.1.2 Pathogenic Microorganisms

Potential microbial stressors in treated wastewater include pathogenic enteric bacteria,
protozoans, and viruses associated with human or animal wastes. Untreated raw sewage
typically contains fecal  indicator bacteria (such as fecal coliforms, total coliforms, and
fecal streptococci) in concentrations ranging from several colonies to tens of millions of
colonies per 100 mL (see Table 6-3). Other pathogens that are potentially present include
other bacteria (Campylobacteriajejuni, Legionella pneumophila, Salmonella typhi,
Shigella, or Vibrio cholerae), helminthes (such as hookworm, roundworm, or tapeworm),
viruses (adenovirus, enteroviruses, hepatitis A, rotavirus, Norwalk agent, parvovirus, and
others), and protozoa (Cryptosporidium parvum,  Giardia lamblia, Balantidium coli,
Entamoeba histolyticd)  (York et al., 2002).
                                      6-13

-------
Table 6-3.    Typical Concentrations of Fecal Indicator Bacteria in Raw Untreated
              Sewage                     !
Wastewater
Source
Raw sewage
Total Coliforms
(colonies per 100 mL)
22 x 106
Fecal Coliforms
(colonies per 100 mL)
8xl06
Fecal Streptococci
(colonies per 100 mL)
1.6 xlO6
Source: Wood et al., 1993, based on data from Geldreich, 1978, for communities in the United States.
For comparison, basic disinfection of secondary-treated wastewater must achieve the
microbial standards of 200 and 2,000 colonies per 100 mL of wastewater for fecal
coliforms and total coliforms, respectively, depending on the type of bacteria involved.
Disinfection to these levels represents reductions of 104 or more.

Although secondary-treated wastewater destined for ocean outfalls is treated with
chlorination, the minimal amount of chlorination needed to meet Class III water quality
standards after dilution is generally used, in order to avoid the adverse effects of
overchlorination. Pathogenic microorganisms that are not affected by secondary
treatment or chlorination include the protozoans Giardia and Cryptosporidium^ which are
resistant because they form cysts that can remain dormant for periods of time and can be
removed only through filtration. Filtration followed by disinfection is effective at
removing viruses, while secondary treatment and chlorination is effective at removing
helminthes (Rose and Carnahan,  1992).

Microbial contamination from enteric viruses, bacteria, and protozoans is a chronic
problem in the Tampa Bay, Sarasota Bay, and Florida Keys coastal environments. This is
probably because of high concentrations of onsite sewage disposal systems, porous sandy
karst soils, and hydrologic connections between groundwater and coastal embayments
and estuaries  (Lipp et al., 2001; Paul et al., 1995). Survival of microorganisms in water is
affected by a number of physical and biological factors, such as ultraviolet radiation and
predation by grazers (Wood et al., 1993). Field measurements around the world provide a
range of values of the time needed for reduction of enteric bacterial populations in
seawater to 90 percent of their original concentrations (that is, t90). These values for t*,
range from 0.6 to 24 hours in daylight to 60 to 100 hours at night (reviewed in Wood et
al., 1993). Enteric viruses tend to survive longer in seawater than do enteric bacteria: at
20 °C, if the tQOfor bacteria was 0.6 to 8 hours, the t,0for enteric viruses was  16 to 24
hours (Feacham et al., 1983). Fecal streptococci tend to be more persistent than fecal
coliforms in seawater (Wood et al., 1993).

The initial SEFLOE experiments involved the monitoring of plumes of unchlorinated
treated effluent in the ocean to determine how dilution and natural attenuation processes
would affect microbial concentrations of fecal coliforms, total coliforms, and enterococci.
To provide guidance on the level of chlorination needed, these data were then used to
calculate what the maximum bacterial concentrations in chlorinated effluent should be to
achieve a given dilution at a given distance from the outfall. Southeast Florida
                                       6-14

-------
 wastewater treatment plants routinely provide secondary treatment and chlorination of
 wastewater to meet these standards (Hazen and Sawyer, 1994).

 Because secondary effluent discharged through ocean outfalls is not filtered to remove
 protozoans such as Giardia or Cryptosporidium^ these protozoans may pose potential
 human health risks that need to be evaluated.

 6.5.1.3 Priority Pollutant Metals

 Metals found in wastewater may constitute potential stressors because of potential human
 health risks and ecological risks. Metals are normally present in trace amounts in
 seawater (Bruland, 1984) and in higher amounts in sediments (Holland, 1978), but their
 concentrations are commonly elevated in wastewater because of the many anthropogenic
 uses of metals. As a consequence, metals are frequently used as tracers of wastewater in
 the ocean (Matthai and Birch, 2000; Flegal et al., 1995; Hershelman et al., 1981; Ravizza
 and Bothner, 1996; Morel et al., 1975). Marine disposal of untreated sewage or sewage
 sludge typically results in elevated concentrations of metals (typically chromium, copper,
 nickel, lead, silver, zinc, and  iron) and other contaminants on the seafloor (Zdanowicz et
 al., 1991; Zdanowicz et al., 1995). Other sources of anthropogenic and natural metals to
 the ocean include stormwater runoff, inputs from surface water (rivers,  streams) and
 groundwater, and atmospheric dust (Burnett and Schaeffer, 1980; Finney and Huh, 1989;
 Forstner and Wittman, 1979; Huh et al., 1992; Huntzicker et al., 1975; Klein and
 Goldberg, 1970).

 Information on metal concentrations in marine organisms from this area includes the
 Mussel Watch Program, which is part of NOAA's National Status and Trends Program
 (NSTP). The NSTP found elevated concentrations of arsenic in oysters  extending from
 the Florida panhandle in the eastern Gulf of Mexico, South Florida (Biscayne  Bay and
 Miami River), and up the east coast of Florida to North Carolina. Potential sources of
 arsenic include both natural sources (phosphorite rocks) and anthropogenic sources (for
 example, anthropogenic  inputs to Biscayne Bay from pesticides in agricultural runoff and
 phosphate mining). Oysters are a food source for humans, birds, and other organisms,
thus there is a potential for secondary  uptake of arsenic (Valette-Silver et al., 1999).
 Because oysters are typically found in nearshore environments and not in deeper shelf
 waters, it is probable that the  arsenic found in these studies originates from more
 nearshore or terrestrial sources, whether anthropogenic or natural. This information
 indicates, however, that such  bioaccumulation is common and needs to be taken into
 consideration when examining the potential effects of secondary effluent discharge into
the ocean.

 6.5.1.4 Organic Compounds

Potential organic stressors that may be present in secondary-treated wastewater include
EPA priority pollutant organic compounds, including volatile organic compounds
(VOCs), synthetic organic compounds (pesticides, herbicides), organochlorine
                                      6-15

-------
compounds such as trihalomethanes, and a variety of other unregulated compounds, such
as endocrine disrupters, surfactants, and organic matter.

6.5.2  Potential Receptors

Potential receptors of ocean outfall effluent constituents include any organism that may
be exposed to seawater containing effluent constituents. Because seawater is not used for
drinking water (unless it is treated through desalination), potential receptors mainly
considered in this risk assessment are those that may be directly exposed to seawater
containing effluent constituents. Such potential receptors in the South Florida marine
environment include a wide variety of animals and plants living in or near brackish
coastal waters or marine waters, including marine mammals, reptiles, fish, birds, marine
invertebrates, and aquatic vegetation. Humans also use the ocean for recreation, fishing,
and other activities and can be exposed by eating contaminated seafood.

6.5.2.1 Ecological Receptors

Marine mammals that may be found in the South Florida coastal and marine environment
include Florida manatees, whales (right, Sei, finback, humpback, sperm), and dolphins. In
coastal brackish and freshwater environments  such as estuaries and rivers, river otters
also occur. The U.S. Fish and Wildlife Services and NOAA list all of these marine
mammals except dolphins as endangered species (FFWCC, 1997).

Reptiles known to occur in marine or brackish South Florida waters include the American
crocodile (endangered), Atlantic salt marsh snake (threatened), gray salt marsh snake,
Atlantic green turtle (endangered), Atlantic hawksbill turtle (endangered), Atlantic
loggerhead turtle (threatened), Atlantic Ridley turtle (endangered), and the leatherback
turtle (endangered) (Carmichael and Williams, 1991; FFWCC, 1997).

The South Florida shelf environment is host to a wide variety of subtropical marine
invertebrates, including mollusks (clams, conchs, snails, octopi, squid), annelids (worms),
arthropods (crabs, lobster, shrimp), coelenterates (corals, sea anemones, echinoderms,
starfish, sea urchins), sponges, bryozoans, and many others (Alevizon, 1994; FFWCC,
1997). These marine organisms feed in a number of ways, including predation,
scavenging, filter-feeding, grazing, and feeding on organic detritus. Predatory
invertebrates include octopi, many snails such as conchs, starfish, and squid. Filter-
feeding organisms include corals, sponges, bryozoans, and bivalves such as clams and
mussels. Some filter-feeding organisms, like certain corals, have symbiotic algae that
help the host animal to survive. Grazing organisms include sea urchins and mollusks.
Detritus feeders and scavengers include many  worms, crabs, lobsters, shrimp, and snails.

The most extensive reefs of South Florida are primarily associated with the Florida Keys,
but reef-forming organisms such as corals, sponges, and bryozoans may be found along
the South Florida coast.  Associated with these reef-forming animals may be found
coralline and encrusting algae, which require solid substrates for attachment. In the
Florida Keys, coral reefs have declined from a combination of factors, not all of which
                                       6-16

-------
 may be manmade. An epidemic disease occurred in the early 1980s, affecting the
 longspined black sea urchins that graze on the macroalgae that compete with corals for
 space. The absence of urchins may account for increased growth of seaweed on the reefs.
 Groundwater nutrient inputs from onsite sewage disposal systems may also account for
 the growth of macroalgal blooms, such as Codium isthmocladum in southeast Florida and
 the Caribbean (LaPointe, 1997; NOAA 2002c).

 Fish species found in Florida waters include yellowtail snapper, grouper, barracuda,
 stingray, parrotfish, porcupine fish, Key blenny (endangered), angelfish, butterflyfish,
 damselfish, goby, trumpetfish, and wrasse, among many others (FFWCC, 1997).

 Birds that may be found in brackish and marine waters include the brown pelican,
 American oystercatcher, frigatebird, piping plover (threatened), roseate spoonbill, roseate
 tern (threatened), cormorant, least tern, and southeastern snowy plover (threatened).
 Many other birds found in more inland brackish to fresh waters include the flamingo,
 heron, kingfisher, little blue heron, osprey, reddish egret,  snowy egret, tricolored heron,
 white ibis, whooping crane, bald eagle, and others (FFWCC, 1997; Williams, 1983).

 6.5.2.2 Human Receptors

 Potential human receptors who may be exposed to ocean outfall effluent include
 recreational and industrial fishermen, boaters, workers associated with ocean outfall
 operations or wastewater treatment and, if the exposure pathways exist, recreational
 swimmers.

 6.5.3   Potential Exposure Pathways

 For nonpotable water, the primary potential exposure pathways are related to direct
 exposure of humans to water containing stressors and ingestion of seafood with elevated
 levels of contaminants. There is also a  possibility of airborne exposure if water droplets
 containing effluent constituents somehow are formed through turbulence or
 aerosolization. Potential primary human exposure pathways for waterborne stressors in
 discharged effluent include ingestion of stressors (followed by bioaccumulation or
 excretion), dermal contact with stressors, and inhalation of water vapor containing
 chemical or microbiological stressors. Recreational or fishing activities in or near the
 ocean outfall could bring humans into a situation where exposure could occur.

 Potential exposure pathways for marine mammals, reptiles, and fish are similar to the
above-named pathways (that is, ingestion, dermal contact, and inhalation). Predation or
 scavenging of other organisms feeding upon contaminated organisms or algae that
 contain elevated tissue concentrations of effluent constituents could also cause
bioaccumulation of these constituents.

Potential exposure pathways for marine invertebrates include ingestion of particles or
dissolved materials containing effluent constituents. Examples include filter-feeding or
detrital-feeding organisms feeding on organic particles containing adsorbed metals or
                                       6-17

-------
organic constituents or ingesting water containing dissolved effluent constituents. Such
organisms may be feeding upon the fecal pellets of other marine organisms that may have
ingested effluent constituents. Predators may feed on other organisms that have already
ingested or bioaccumulated constituents such as metals or organic compounds.

Settling organic and inorganic particles in the ocean represent a significant mass transport
mechanism for the cycling of particles from the surface of the ocean to the seafloor. Such
settling particles can scavenge other materials in the water column by adsorption or other
complexation processes (Honjo et al., 1982). Fecal pellets produced by zooplankton settle
to the sea floor as organic detritus, thereby providing a conduit for the rapid removal of
nutrients and other substances from the upper layers of the ocean to the deeper layers of
the ocean (Pilskaln and Honjo, 1987). Much of the organic matter found on the seafloor
ultimately derives from primary and secondary production in the photic zone, which is
typically 10 m deep (Parsons et al., 1984).

Unlikely exposure pathways include direct exposure of shallow shelf or photic zone
organisms to discharged effluent. Receptors could be exposed to stressors from the
physical transport of stressors towards the coast. For example, if the Florida Current were
to move nearshore or if an eddy of the Florida Current were to transport effluent
constituents, then nearshore or onshore receptors could be exposed to effluent
constituents.

The question of whether exposure and uptake pathways exist is crucial for risk
assessment. The primary risk questions to be asked are these:

    •   Do these actual exposure pathways exist?
    •   If they do exist, is there actual uptake?
    •   If there is uptake, are there adverse effects upon humans or biota?

Unless seawater is used for desalination for a drinking-water source, the primary type of
human risk that might occur would be related to recreational or occupational exposures to
seawater and consumption of seafood.

6.5.4   Conceptual Model  of Potential Risk for Ocean Outfalls

A conceptual risk model is a generic model of potential risks that may result from
management of treated municipal wastewater using ocean outfalls. Such a model lists all
potential exposure pathways and processes that control whether a receptor is actually
exposed to a stressor or not. This conceptual model of potential risk represents the risk
model to be tested using specific data. Section 6.6 describes the data and the testing of the
model. It contains an evaluation of how realistic the potential risks are. A conceptual
model for evaluating potential risks associated with ocean outfalls is shown in Figure 6-4.

The model components that control the fate and transport of wastewater discharged into
the open ocean environment were adapted from a 1984 National Academy of Science
study entitled "Disposal of Industrial and Domestic Wastes: Land and Sea Alternatives"
                                       6-18

-------
and the Waquoit Bay National Estuarine Research Reserve Watershed risk assessment
model that provides a method for identifying valued natural resources and evaluating the
risk to those resources (Bowen et al, 2001).

In this conceptual model, the source of stressors is the wastewater treatment plant
providing secondary treatment and basic disinfection of municipal wastewater derived
from industrial and domestic sources. The potential stressors are inorganic compounds
(for example, metals, salts), organic compounds, nutrients, and pathogenic
microorganisms.

The physical pathways and processes that occur when treated wastewater is discharged
into any water body, either open ocean or surface water (such as rivers, lagoons, or
estuaries), are extremely important in determining large-scale exposure pathways. In the
vicinity of the outfall, the ways in which ocean currents affect dispersion and dilution of
the effluent plume are extremely important. Farther away from the outfall, as dilution
occurs, it is important to determine whether ocean circulation and mixing could vary
enough to expose terrestrial or nearshore receptors.

Physical processes refers to the transport process that moves suspended or dissolved
materials from one place to another (National Academy of Sciences, 1984). Examples
include advection of a plume through current movement, dilution or dispersion of the
plume through mixing with surrounding waters, density-driven advection, sedimentation
of solids from the plume to the benthos, resuspension of sediment through turbulence or
bioturbation, adsorption, and volatilization to the atmosphere.

Potential chemical processes are chemical reactions that wastewater constituents can
undergo when discharged into the aquatic environment. These processes include
adsorption and desorption, changes in oxidation state, precipitation and dissolution,
photodegradation, transformation, and  complex formation.

Potential biological processes affecting the fate and transport of stressors include uptake,
bioconcentration and accumulation of stressors, inactivation of pathogenic
microorganisms, biochemical transformation or degradation of stressors, photosynthesis,
and the formation of organic marine particles such as zooplankton fecal pellets that
transport stressors to benthic habitats. Both chemical and biological processes determine
the fate and effect of a particular constituent.
                                       6-19

-------
                 Activity / Sources
                    of Stressors
                Waste water Treatment I
                    Plant Discharge    I
System Stressors      Pathways / Processes
ON
i
N)
O
                                                 Inorganic
                                                 Compounds
                                                 {metals, solids, satt}
                                                  Volatile Organic
                                                  Compounds
  Synthetic Organic
  Constituents
                                                  Microbiological
                                                  Constituents
                                                  Miscellaneous
                                                  Constituents
                           Biological Processes

                             Pathogen Mortality
                             Bioconcentration
                             Bioaccumulation
                             Biodegradation
                             Biochemical Transformation
                             Respiration
                             Photosynthesis
                             Bioturbation
Chemical Processes

  Adsorption / Desorption
  Oxidation / Reduction
  Precipitation/ Dissolution
  Photodegradation
  Chemical Transformation
  Complex Formation
  Physiochemical
  Gradients
                           Physical Processes
                             Dispersion by Currents
                             Advection / Diffusion
                             Dilution
                             Buoyancy
                             Sedimentation / Coagulation
                             Sediment Resuspension
                             Light Transmission
                             Volatilization to Atmosphere
                                   Sensitive Receptors
                                    Phytoplankton and Zooplankton
                                    Submerged Aquatic Vegetation (SAV)
                                    Macroinvertebrates
                                    (e.g., coral reefs, shellfish, etc.)
                                    Fish
                                    Birds
                                    Marine Mammals
                                    Marine Reptiles
                                    Endangered Species
                                    Humans
Potential Ecological Effects
 Eutrophication (excess nutrients and algal
   growth, low oxygen)
 Harmful Algal Btooms (HABs)
 Changes in Phytoplankton and Zooplankton
   Communities
 Toxic Effects on Marine Species
 Developmental or Reproductive Changes
 Reduced Growth of SAV due to Reduction
   in Water Clarity
 Illness Caused by Microbial Pathogens
 Food Web Effects
                                                                                                           Reference: Disposal of Industrial and Domestic Wastes:
                                                                                                           Land and Sea Alternatives, National Academy
                                                                                                           of Sciences, 1984.
               Figure 6-4.  Conceptual Model of Potential Risks for the Ocean Outfall Option

-------
Potential receptors include submerged aquatic vegetation, plankton (phytoplankton,
izooplankton), larger aquatic organisms (invertebrates, fish, marine mammals, and
reptiles), birds, and humans. There are no drinking-water receptors in this conceptual
model. If seawater were to be used for a drinking-water source through desalinization,
which is being considered in South Florida, then this potential receptor would be added to
the conceptual model. However, seawater in coastal areas would contain many of the
same stressors derived from other sources on land.

6.6    Risk Analysis of Ocean Outfalls

In this section, the potential risk model expressed by the conceptual model is tested using
actual data from existing ocean outfalls or the SEFLOE studies. As part of the risk
analysis, the following questions will be answered:

    •  Do plausible exposure pathways exist for receptors to be exposed to stressors?
    •  Are concentrations of stressors high enough to potentially cause adverse effects?
    •  Is there evidence for adverse effects in receptors caused by exposure to stressors
       derived from treated wastewater effluent?

6.6.1  Evaluation of Physical Transport

In order to appreciate the large-scale risk setting, it is important to understand physical
environmental risk factors. These are the physical features of the environment that play a
significant role in the risk of a particular wastewater management option. A thorough
understanding of physical oceanography, circulation, mixing, dispersion, and dilution of
the discharged effluent plume at the ocean outfalls is necessary for evaluating the
physical environmental risk factors associated with ocean outfalls.

The SEFLOE studies and other related studies provide much of the information needed to
assess such risk factors. Intensive cruises were conducted to each outfall during winter
and summer to detect and track, using acoustic measurements, the initial plume and to
develop two-dimensional models of the effluent plumes. To map and model current
velocities and water column structure, moored current monitors were deployed near
outfall discharge sites for several periods between August 1991 and October 1992. An
acoustic Doppler current profiler was deployed at the Miami-Central outfall diffuser in
the summer of 1992 to obtain more information on current regimes and depth variations
in currents. Dye and salinity tracking were also used to map the distribution and
movements of water masses. Water-column characteristics (conductivity, temperature,
and depth, or  CTD) were measured using CTD water-column profiling on a semimonthly
basis at each outfall from July 1991 to October 1992 (except months when intensive
cruises were underway). Physical characteristics of the surfacing effluent plumes were
monitored using towed CTDs. Initial and subsequent dilutions were estimated, using
differences in salinity between the effluent and ambient seawater as a tracer.

The SEFLOE studies also collected water-quality information from the effluent plume
and from ambient seawater. Parameters measured included bacteria (total coliforms, fecal
                                      6-21

-------
coliforms, and Enterococcus bacteria), nutrients (ammonia, total Kjeldahl nitrogen
(TKN), total phosphorus, nitrate, nitrite), oil and grease, 126 priority pollutants, and total
suspended solids (TSS). Effluent samples from the six wastewater treatment facilities
were also analyzed for salinity, bacteria, nutrients, priority pollutants, oil and grease,
CBOD5,andTSS.

6.6.1.1 Transport, Dispersion, and Dilution by Currents

Transport, dispersion, and dilution of effluent plumes by ocean currents and circulation
are critical risk factors for evaluating potential risks of ocean outfalls. The direction and
speed of current flow, which together determine current velocity, are critically important
risk factors. The faster the current speed is at the outfall, the greater the rate at which the
plume is dispersed and diluted by ambient seawater, and the lower the concentration of
stressors. Conversely, the slower the current speed is at the outfall, the lower the rate at
which the plume is dispersed and diluted by ambient seawater, and the higher the
concentration of stressors remaining in the area. The direction of current flow, away from
or towards human or ecological receptors, is also important to characterize. Current flow
towards the coast will increase the likelihood that coastal receptors (human or ecological)
will be exposed to effluent constituents, while current flow away from the coast will
decrease the likelihood of exposure.

The SEFLOE II study provided an extensive set of current measurements and water-
column density profiles, using a combination of acoustical backscatter and direct
sampling methods. Information on water quality of the effluent plume and ambient
seawater also was obtained. Analysis of the current data from the four outfall locations
indicated that three major current regimes, characterized by different flow directions,
were present at all outfall sites:

   •   Current Regime i = Northerly flows, thought to be associated with western
       meanders of the Florida Current
   •   Current Regime ii = Southerly flows, which are part of an extensive eddy current
   •   Current Regime Hi = Rotary-like flow, which consists of groups of rotations
       interspersed between northerly and southerly flows. The rotations were irregular
       and temporally fleeting, with durations of 5 to 8 hours.

Current Regime / predominates, displaying rapid current flow in a northerly direction
throughout the entire water column. The SEFLOE II study reports that this current flow
occurs approximately 60% of the time. Current Regime ii,  representing southerly flow,
occurs approximately 30% of the time. Current Regime HI, representing flow in other
directions (easterly, westerly) occurs irregularly and less than 10% of the time, and the
duration of such flows is very short (5 to 8 hours).

To estimate the percentage of time that Current Regime Hi flows to the west, data  points
reflecting current direction at a depth of 16.8 m at the Miami-Dade Central District
wastewater treatment plant (Hazen and Sawyer, 1994) were visually analyzed. It was
assumed that, as described in the SEFLOE II report, easterly and westerly flows occur a
                                       6-22

-------
total of 10% of the time. This analysis indicates that westerly flows occur approximately
4% percent of the time, while easterly flows occur approximately 6% percent of the time.
Data sets using an Aanderaa current meter and using an acoustic Doppler current profiler
yielded equivalent results.

The Florida Current in the vicinity of the ocean outfalls can be characterized as a fast-
flowing current, with speeds ranging from approximately less than 5 centimeters per
second (cm/sec) to maximum speeds of over 60 to 70 cm/sec. In general, the mean
current velocity observed during Regime / northerly current flow is greater than any other
current regime, while the mean current velocity of Regime Hi rotary-like flow is the
lowest (Hazen and Sawyer,  1994). Because the dilution of the effluent plumes is a
function of current velocity, the Regime Hi rotary-like flow will result in the higher
concentration of stressors.

For the purposes of evaluating plume dispersal, the SEFLOEII report used the lowest 4-
day average current speeds and the lowest lOth-percentile average current speeds as
conservative (that is, protective) estimates of average current speeds. These current
speeds are shown in Table 6-4 (Hazen and Sawyer, 1994). The maximum current speeds
recorded during the study are shown for comparison. In general,  the average current
speeds are highest at the Broward outfall.

Table 6-4.    Average Current Speeds (cm/sec)
Outfall
Broward
Hollywood
Miami-Dade North
Miami-Dade Central
Lowest 4-Day Average
Current Speed
15.7
13.7
13.2
13.6
Lowest lOth-Percentile
Average Current Speed
12.3
7.8
7.7
11.6
Maximum
Current Speed
>70
>60
>70
>70
Source: Hazen and Sawyer, 1994.
Irrespective of which current regime was predominant, current direction was generally
the same at all depths, based on water column profiles. Slight variations in current speed
occurred throughout the water column, with higher speeds occurring near the ocean
surface.

6.6.1.2 Dilution of the Effluent Plume

The SEFLOE I study characterized dilution of the effluent plumes at all six of the ocean
outfalls, using dye and salinity data and acoustic backscattering methods.  Based on these
studies, the effluent plume typically has three distinct phases:

   1.  The initial dilution phase commences when the effluent leaves the outfall pipe and
       lasts until the effluent reaches the surface of the ocean.
   2.  The near-field dilution phase commences when the plume reaches the surface and
       undergoes radial dispersion because of the momentum of the rising effluent
                                      6-23

-------
       within the upper 3 m of the ocean surface. This phase is visible on the surface of
       the ocean as a feature that is often called a "boil."
    3.  The farfield dilution phase is characterized by an effluent plume that has
       undergone dilution during the initial and near-field dilution phases and is further
       dispersed by surface currents.

The characteristics of each of these dilution phases are discussed below.

Initial and Near-Field Dilution

Because the water samples are collected at or near the boil, within 1 m of the surface, the
sampling actually is conducted within both the initial and near-field dilution phases, as
defined above in the SEFLOE study. Therefore, these two dilution phases are discussed
together in this  section.

Initial dilution using tracer dye methods and chlorine was defined in the SEFLOE study
as the ratio of measured concentrations of the dye in the effluent boil to the initial
concentration of the dye in the effluent at the treatment facility. The initial dilution that
occurs over a 4-day period at a conservative current speed (worst-case scenario with the
lowest average  current speed) is described in Table 6-5 below as the flux-averaged initial
dilution factor.  The greater this factor is, the higher the dilution.

Table 6-5.   Flux-Averaged Initial Dilution of Effluent Plume.
Ocean Outfall
Broward
Hollywood
Miami-Dade North
Miami-Dade Central
Lowest 4-day Average
Current Speed (cm/s)
15.7
13.7
13.2
13.6
Flux-Averaged Initial
Dilution Factor
43.3
28.4
50.1
28.3
Source: Hazen and Sawyer, 1994, Table HI-5.
The initial dilution factors from the SEFLOE studies indicate that initial dilutions were
highest for the Miami-Dade North ocean outfall and lowest for the Miami-Dade Central
and Hollywood outfalls. Yet, according to Table 6-5, Miami-Dade North outfall had the
lowest 4-day average current speed. The high initial dilution at this outfall may explained
by the use of multiport diffusers at the Miami-Dade North outfall. The use of multiport
diffusers at the Miami-Dade North outfall appears to aid in dispersal of the effluent
plume over a wider area, thereby decreasing potential risk. However, these effluent
plumes were diluted at slower rates than the effluent plumes from the Hollywood and
Broward outfall plumes, according to Englehardt et al. (2001).

The rate of initial dilution of the effluent also is largely dependent upon the current speed
and the rate of discharge of effluent from the outfall. As current speed increases, dilution
also increases. As the rate of effluent discharged from the outfall increases, the rate of
dilution increases. These relationships are shown in Figure 6-5, which shows flux-
                                       6-24

-------
averaged dilution vs. current speed for effluent discharged from the Miami-Dade Central
ocean outfall (from Hazen and Sawyer, 1994).

At a lower current speed of 10 cm/sec at a 253 mgd discharge rate, the dilution factor is
approximately 20; at a higher current speed of, say, 60 cm/sec, the dilution factor is over
40, Also, for a given current speed, at higher discharge rates (that is, 253 mgd), the
dilution is lower than if effluent is discharged at a lower rate (that is, 115 mgd).

The SEFLOE study found that normally surfacing plumes were present at all outfalls
throughout the year, even in summer months when density stratification of the water
column was weak. It is noteworthy, however, that during several strong stratification
events, portions of rising plumes were trapped and prevented from freely dispersing,
based on acoustic profiling conducted by John Proni and colleagues (Proni et al., 1996,
1994; and Proni and Williams, 1997). In such areas of plume trapping, effluent
constituents  were present at relatively higher concentrations than in areas in which there
was no such trapping and the effluent was freely dispersed. Concentrations of effluent
constituents  were, however, quite low, but their existence is quite significant. Definitive
measurements of dilution in trapped plumes are planned for an upcoming SEFLOE III
study (John Proni, personal communication). Plume trapping during strong stratification
events therefore represents one potential risk factor.

Farfield Dilution

The SEFLOE II report indicates that measurements of farfield dilutions were the most
difficult'field measurements to obtain. Measurements of salinity, dye concentration, and
acoustic backscatter intensity were used simultaneously for dilution calculations and to
guide sampling for biological and chemical parameters for subsequent dilution
determinations. Subsequent dilution is defined in the SEFLOE report as dilution that
occurs as plume elements move away from the boil location, which represents the initial
dilution and  near-field dilution phases.

Average subsequent dilutions in the near-field and farfield for the four ocean outfalls are
compared in Figure 6-6, which plots the inverse of total physical dilution (I/total physical
dilution) of the plume on a logarithmic scale against the distance from the boil in meters
(from Hazen and Sawyer, 1994, Figure 111-77). On this plot, as one moves away from the
boil, dilution increases. Figure 6-6 shows the following:

    •  Treated effluent discharged from the Broward and Hollywood outfalls
      experiences more rapid dilution in the 0- to 100-m range than the effluent
      discharged from the two Miami-Dade outfalls. These two outfalls have larger
      diameter ports than the other ocean outfalls (see Table 6-1).
    •  Between 100 and 200 m from the plume boil, there is a change in the rate of
      dilution, suggesting that buoyancy spreading and positive buoyancy of the plumes
      is still occurring at this distance from the outfall.
                                      6-25

-------
ON

to
o\
                        u -n
                        ft?
                          ,,
                        i. ^

                        6 u
                        QJ 3
                        Q. ?
                        CD D
                        0 =
                        C Dl
c
3
O
i-*

o'
3

O
^»

U
c
                          u
                          •o
                          (D
                          (D
                          a
                          Dl
                          3
                          a
                          o
                          y
                          0)

                          (Q
                          (D
                     Flux-averaged dilution

-------
        1.000
m
o


1,
£
a

"ro
4-i
O
        0.100
        0.010
        0.001
Miami - Dade Central
             0    100   200   300   400   500   600   700   800   900   1000






                                  Distance from Boil (m)



                                                       Source: Hazen and Sawyer, 1994
Figure 6-6. Total Physical Dilution as a Function of Distance from the Boil

(Four Ocean Outfalls)
                                   6-27

-------
    •   Between 100 m and 400 m from the boil, total physical dilution with distance
       curves are approximately similar for both current Regimes / (northerly flow) and
       H (southerly flow), with average dilutions ranging from approximately 60:1 to
       90:1 at a distance of 400 m from the boil location.
    •   Dilution rate increases slightly at 500 m from the boil for Broward, 700 m from
       the boil  for Miami-Dade Central, and 600 m from the boil for Hollywood outfalls.
       The effluent plume from the Miami-Dade North outfall shows steady dilution
       throughout nearly the entire distance sampled.
                                                     T
Note that the 400-m mixing zone equates to the 502,655 m maximum mixing zone size
for open ocean outfalls regulated by the state of Florida. Dilutions ranging from 60:1 to
90:1 were used  to evaluate the concentrations of the measured constituents of concern in
wastewater and were compared to the Class III standards.

The information from the SEFLOE studies indicates that overall dispersal and dilution of
the discharged effluent occurs rapidly, within hours to days, and that the mixture of
effluent and receiving water rapidly achieves background or near-background
concentrations of tracer dyes and salinity within 400 to 600+ m of the outfall. Rapid
dispersal results in dilution of the effluent  and therefore reduces the risk of exposure to
undiluted effluent.

6.6.2   Evaluation of Stressors, Exposure Pathways,  and Receptors

In this section, information from the SEFLOE studies and other studies are used to
evaluate the following risk questions posed by the conceptual model:

    •   Do concentrations of stressors exceed standards  intended to protect human health
       or ecological systems?
    •   Is there evidence that human or ecological receptors are exposed to or take up
       stressors derived from the treated effluent or secondary stressors that are created
       by discharge of effluent?
    •   Is there evidence of adverse effects on human or ecological receptors in the
       vicinity  of the outfalls?
    •   If there are adverse effects that can be attributed to the use of ocean outfalls, are
       these effects reversible?

6.6.2.1 Pathogenic Microorganisms

Pathogenic Microorganisms in Unchlorinated Effluent as a Worst-Case Scenario

The SEFLOE study measured three types of bacteria indicative of mammalian wastes:
total coliforms,  fecal coliforms and Enterococcus, Samples for microbiological analysis
were taken from both secondary treated unchlorinated effluent and from within the
effluent plume itself (Hazen and Sawyer, 1994). Based on these measurements and the
effluent plume characteristics, SEFLOE provided recommendations to regulators
                                       6-28

-------
 concerning the width of the mixing zones that would have to be defined to allow dilution
 of the effluent to meet Florida water-quality criteria for bacteria.

 Recommendations on the maximum allowable concentrations of bacteria in effluent were
 also provided to help guide treatment plant operators in determining the correct amount
 of chlorine to use in disinfecting effluent. Florida regulations require basic disinfection to
 meet a standard of 200 fecal coliforms per 100 mL of treated wastewater. However,
 because chlorine disinfection itself can create unwanted chlorinated byproducts (for
 example, trihalomehanes) and pose potential health or environmental risks, the
 regulations also allow for an effluent mixing zone range. This allows dilution of effluent,
 reducing the amount of chlorine used, while still meeting water-quality standards.
 SEFLOE's recommended widths of mixing zones of unchlorinated effluent to achieve
 Class III bacterial water quality standards are summarized in Table 6-6.

 Table 6-6.    Recommended Mixing Zone Ranges for Unchlorinated Effluent,
              Using Different Methods of Calculating Bacterial Concentrations
Facility
Broward County
Total coliform
Fecal coliform
Enterococci
City of Hollywood
Total coliform
Fecal coliform
Enterococci
Miami-Dade North
Total coliform
Fecal coliform
Enterococci
Miami-Dade Central
Total coliform
Fecal coliform
Enterococci
Radial Distance (m)
Maximum Single
Requirement
900
800
800
900

500
200
1,000

900
900
1,000

Uncertain
900
Uncertain
Percent Not
Greater Than
Requirement
900
800
800
900

800
700
800

900
900
1,000

Uncertain
900
Uncertain
Geometric Mean
Requirement
400
400
400
400

0
0
400

400
400
800+

800
800+
800+
Range of
Controlling
Criterion
900
800
800
900

80
700
1,000

900
900
1,000

Uncertain
900
Uncertain
Note: Data from Miami-Dade Central are shown as uncertain because of suspected high background concentrations of
indicator bacteria from the Miami River.
Source: Hazen and Sawyer, 1994.

Because these values represent distances that the unchlorinated effluent would have to
travel before the concentration of bacteria became diluted to background levels, they
provide information for an evaluation of one potential worst-case risk scenario, which is
failure of chlorination to treat secondary effluent to meet Class III water-quality
standards. In general, the results show that even if unchlorinated effluent were
discharged, it would become dilute enough to meet Class III bacteriological water quality
standards within 800 to 900 m of the outfall or, in some cases, much closer.
                                       6-29

-------
Disinfection To Achieve Microbial Standards
                                                                'y
The Florida regulations require a mixing zone area of up to 502,655 m to allow dilution
of the effluent to Class III water-quality standards. Although the Florida regulations do
not require that a circular mixing zone be established, and in fact do not specify a shape,
the  use of a circular mixing zone for evaluating whether dilution achieves the standards
makes it easier to compare actual versus expected concentrations of effluent constituents.
Such a circular mixing zone would have a radius of 400 m.  It is worth noting, however,
that a circular mixing zone would occur only in an environment where there is no current
flow.

To assist facility operators in determining how to manage bacteria to meet Class III
regulatory standards, SEFLOE provided calculations of the maximum allowable numbers
of indicator bacteria in effluent within 400 m of the outfall. These calculated
concentrations are shown in Table 6-7. They include assumptions concerning microbial
attenuation processes that are not based solely on physical dilution alone (John Proni,
personal communication). These bacterial numbers provide wastewater treatment facility
operators with specific bacterial concentration goals to  meet, using chlorination of
effluent in order to meet Class III water-quality standards. The 800-m mixing zone is
included because, as stated above, the mixing zone is not required to be a circular mixing
zone but instead is an area, and the effluent plume may well extend outside of the 400-m-
radius zone.

Table 6-7.    Maximum Allowable Concentrations of Indicator Bacteria in Effluent
             within Different Mixing Zones
Facility
0 m Initial
Dilution Zone
400m
Mixing Zone
800m
Mixing Zone
Broward County
Total coliform
Fecal coliform
Enterococci
302
72.6
_.
3,388
437.6
284
10,471
935
53
City of Hollywood
Total coliform
Fecal coliform
Enterococci
575
296
7.3
2,884
324
38.4
3,631
1626
106
Mia mi-Da de North District
Total coliform
Fecal coliform
Enterococci
3,715
1,517
153
14,454
20,465
840
28,840
7,962
879
Miami-Dade Central District
Total coliform
Fecal coliform
Enterococci
186
68
2.4
417
252
29.0
11,000
1,910
334.0
Note: All bacterial numbers = 100 per 1000 mL
Source: Hazen and Sawyer. 1994, Table 111-17.
                                       6-30

-------
 Proximity of Effluent Plume to Coastal Receptors

 One significant microbiological risk factor is the proximity of the ocean outfalls to land
 and to potential terrestrial and nearshore receptors. If one assumes that the required
 mixing zone area of 502,655 m2 is translated into a circle of radius 400 m centered on the
 outfall, one can compare this with the actual distance of the outfall from land (Table 6-8).
 This table indicates that the highest risk outfalls, solely in terms of distance from shore,
 are the Del Ray Beach and Boca Raton outfalls, while the lowest risk outfall in terms of
 distance is the Miami-Dade Central outfall.

 Table 6-8.    Comparison of Circular Mixing Radii for Effluent and Outfall
              Distance from Shore (m)
Parameter
Distance offshore
Distance from 400
m circle to land
Distance from 800
m circle to land
Miami-Dade
Central
District
5,730
5,330
4,930
Miami-Miami-
Dade North
District
3,350
2,950
2,550
City of
Hollywood
3,050
2,650
2,250
Broward
County
2,130
1,703
1,330
Delray
Beach
1,600
1,200
800
Boca
Raton
1,515
1,115
715
Note: A 400-m mixing radius is required for chlorinated effluent to meet Class HI bacteriological standards. If the
effluent is unchlorinated, an 800-m mixing radius is required.
Source: Hazen and Sawyer, 1994.
It is important to note that in reality the effluent plumes do not disperse equally over a
circular area, as implied by the circular mixing zone calculations used by the SEFLOE
study, but are instead dispersed by the strong Florida Current to form an extended plume,
whose longest dimension is aligned with the northerly flowing Florida Current. It is not
known what would happen if the northerly current flow were to weaken or disappear. It is
probable that, for such a major change in the Florida Current to occur, there would have
to be major changes in ocean circulation elsewhere as well.

There are a number of gaps in information concerning human health and ecological risks
from pathogenic microorganisms remaining in treated effluent. The SEFLOE studies of
enteric microorganisms in effluent and the dilute effluent plume did not include
measurements of Cryptosporidium or Giardia. Other enteric viruses and bacteria were
not measured. Ecological risks posed by effluent microorganisms could not be evaluated
in this report because of the lack of long-term monitoring studies of benthic organisms in
the effluent plume track or adjacent waters.

Human health risks posed by effluent microorganisms also could not be evaluated
directly because of the lack of information on pathogenic microorganisms in coastal
waters adjacent to the outfalls and derived from the outfalls. Beach water-quality
information would provide information on microbial concentrations, but would not
distinguish between onshore versus offshore sources of pathogenic microorganisms.
Many onshore sources of pathogenic microorganisms undoubtedly exist in southeast
                                       6-31

-------
Florida, from a combination of intensive urban and agricultural activities. To distinguish
between these different sources, a tracer study involving microbial tracers or combined
microbial/chemical/biochemical tracers would have to be conducted. However, it remains
clear that there is a risk from pathogenic protozoans such as Cryptosporidium^ which is
not addressed by chlorination, and that the risk is highest during the westward-flowing
current phase, which occurs approximately 4% of the time.

Nevertheless, the SEFLOE studies provide a significant body of knowledge for risk
managers to understand the processes that affect microbiological risks to human health.
They also provide specific recommendations concerning the level of dilution and
disinfection of treated wastewater needed to achieve Class III water-quality standards for
microbial indicators of wastewater (fecal coliforms, Enterococcus, total coliforms) at a
hypothetical 400 -m-radius mixing zone. Although the SEFLOE studies do not provide
follow-up monitoring to confirm that these standards are indeed met all of the time,
monitoring of chlorinated treated wastewater at treatment facilities suggests that these
microbial standards for regulated pathogens and indicator bacteria are nearly always met.

6.6.2.2 Nutrients

There are three questions that must be addressed in order to evaluate potential risks from
nutrients in the secondary treated effluent:

    •   Are nutrient levels in the effluent higher than ambient water or applicable marine
       water-quality standards to protect ecological health?
    •   Is there evidence that nutrients from the treated effluent are taken up by
       phytoplankton and microalgae and then converted to biomass?
    •   Is there evidence of ecological effects from nutrient inputs from the effluent
       plume?

To evaluate ecological risks associated with nutrient discharge, information on effluent
nutrient concentrations was compared with Florida water-quality standards designed to
protect aquatic ecosystems. The Class III Florida water-quality standards state, "In no
case shall nutrient concentrations of a body of water be altered so as to cause an
imbalance in natural populations of aquatic flora or fauna." Therefore, it is also valuable
to compare nutrient concentrations in secondary treated effluent with nutrient
concentrations in ambient seawater at the site, because natural populations of organisms
will be adapted to the ambient concentrations and may experience changes if nutrient
concentrations change.

Table 6-9 compares the nutrient concentrations in secondary effluent, ambient seawater,
and 400 m and 800 m mixing zones at three ocean outfalls (from Hazen and Sawyer,
1994, Tables III-18, III-19 and 111-20). All values in the table  are from Hazen and Sawyer
(1994) unless otherwise noted as calculated for this report. The 800 m mixing zone is
included as a conservative approach.
                                       6-32

-------
        Table 6-9.   Nutrient Concentrations in Secondary Treated Effluent, Ambient Water, and 400 m and 800 m Mixing Zones for
                      Three Ocean Outfalls
Parameter
Ammonia (mg/L)
Mean
Max.
No. of
Samples
Other
Values
Nitrate (mg/L)
Mean
Max.
No. of
Samples
Other
Values
Total Phosphorus (mg/L)
Mean
Max.
No. of
Samples
Other
Values
Broward
Ambient water
Effluent
Boil
400m
800m
Dilution at 400 m**
Dilution at 800m**
0.09
12.48
0.35
0.13
0.11
96x
113x
0.5
20.0
0.9
0.35
0.5


28
42
55
32
26



8.7 d





0.16
0.42
0.12
0.02
0.01
21x
42x
0.16
1.08
0.46
0.02
0.01


1
7
9
1
1



0.64a,9.6b,0.28c3.8d





0.08
1.66
0.18
0.10
0.10
16.6x
16.6x
0.16
2.45
0.84
0.3
0.13


17
43
41
25
21



1.33d





Hollywood
Ambient water
Effluent
Boil
400m
800m
Dilution at 400 m**
Dilution at 800 m**
Parameter
0.09
5.96
0.25
0.09
0.09
66x
66x
0.14
14.00
0.80
0.12
0.12


8
31
15
4
4









Ammonia (mg/L)
Mean
Max.
No. of
Samples
Other
Values
0.11
1.70*
0.16
0.12
0.11
14x
15.5x
0.11
1.60*
0.52
0.30
1.40


9
31
15
4
3









TKN (mg/L)
Mean
Max.
No. of
Samples
Other
Values
0.09
0.97
0.11
0.10
0.10
9.7x
9.7x


0.11
1.60
0.40
0.10
0.10




6
32
12
2
3













Miami-Bade North
Ambient water
Effluent
Boil
400m
800m
Dilution at 400 m**
Dilution at 800 m**
0.66
10.46
0.56
0.10
0.38
105x
28x
1.96
13.7
2.24
0.15
0.84


4
11
10
2
4









0.72
13.4
0.6
0.19
0.61
71x
22x
2.24
17.4
3.64
0.4
1.96


14
11
28
9
13









—
—
—
~
..


—
„
..
—
..


.
—
~
~
..









Ox
            These values are listed here as reported in the SEFLOEII report (Hazen and Sawyer, 1994).
            Calculated for this report using the ratio of observed concentration at the distance indicated to the initial concentration in effluent.
            a = Miami-Dade North District, 1999. See Appendix Table 1-2.
            b = Brevard County (South Beaches WWTF), 2000. See Appendix Table 1-2.
            c = Albert Whined WRF, St. Petersburg. See Appendix Table 1-2.
            d = Mean value from Englehardt et al. (2001), compiled from several sources.  See Appendix Table 1-2.

-------
These data indicate that there are site-specific differences in whether or not the effluent
nutrients become diluted to background levels by the time the effluent water reaches a
distance of 800 m from the outfall. For example, at Broward, the average ammonia
concentration in the plume did not reach ambient levels at 800 m. The average nitrate
concentrations in the boil did not exceed background concentrations at the boil, although
there are individual boil values which exceed background (John Proni, personal
communication). Average total phosphorus in the plume did not reach background
concentrations at 800 m.

There is also considerable variability in the concentrations and data as well; for example,
the background value for nitrate is 0.16 mg/L based on 1 measurement, while the mean
concentration of nitrate at the boil is 0.12 mg/L (9 measurements) and the concentration
of nitrate at 400 m is 0.02 mg/L (1 measurement). Differences in time of sampling could
account for these differences, as well as natural variability.

At the Hollywood outfall, average ammonia concentrations in the effluent plume reached
background levels at 400 m, perhaps partly because the initial effluent concentration of
ammonia was lower than at Broward. Nitrate concentrations in the plume did not reach
background concentrations until 400 m out from the outfall. Total phosphorus did not
reach background concentrations even at 800 m, similar to the Broward outfall.

At the Miami-Dade North outfall, ammonia at the boil did not exceed background
concentrations. Concentrations of nitrate and phosphorus at this location were not
reported in the SEFLOE study.

The calculated dilutions at 400 m and 800 m indicate that there are differences in dilution
of ammonia, nitrate, and total phosphorus  as the effluent plume becomes dispersed.
Ammonia appears to dissipate most rapidly, nitrate may or may not become diluted to
background concentrations at a distance of 400 m, and total phosphorus may not become
diluted to background concentrations even at a distance of 800 m from the outfall. These
differences in dilution may be from the differences in chemical behavior, natural
variability in concentrations, differences in sampling time or location, or a combination
of all of these factors.
The variability in dilution factors calculated using measurements of nutrient
concentrations do provide an illustration of how the actual behavior of wastewater
constituents (for example, nutrients) as measured in situ at a given time may deviate from
the ideal modeled dilution factors, even if the modeled dilutions are based on the use of
actual data on distributions of conservative tracers such as salinity, dyes, or density. To
do a detailed analysis of nutrient dilution as the effluent plume moves further from the
outfall, a specific study designed to track nutrient concentrations and composition would
need to be conducted. Such a study should examine all inorganic and organic phases of
nitrogen and phosphorus, as well as use stable isotope tracers to track effluent nitrogen
and organic matter. The same is true for dissolved organic matter, which is not addressed
in the SEFLOE study. The physical oceanographic conditions present during such a study
would have to be documented as well, since it would be highly possible  for dynamic
                                       6-34

-------
changes in local current flow to disrupt an otherwise orderly plume tracking experiment.
It should be noted that nutrient fate and transport was not a focus of the SEFLOE studies
as reported in Hazen and Sawyer. A study of nutrient fate and transport, based on the use
of stable isotope tracers, is described below (Hoch et al., 1995).

At the time of the SEFLOE II studies, there was concern that nutrients from the discharge
of wastewater into the open ocean was causing enhanced growth of Codium, an algae
observed in 1991 and 1992 on several southeast Florida coral reefs. The SEFLOE II
reports gives several reasons as to why the nutrients discharged from the outfalls are not
likely to cause increases in Codium (Hazen and Sawyer, 1994), as summarized below:

    •  Codium plants require attachment to a solid substrate in order to grow, while the
       outfall plume rises. Thus, Codium habitat is not exposed directly to the effluent
       plume.
    •  Attached Codium plants were not present near the outfall sites where nutrient
       levels are above background-seawater levels.
    *  Codium attaches to solid substrate in deeper waters, outside of the nutrient
       dispersal area associated with the outfalls. The effluent nutrient levels quickly
       reach background concentrations within a short distance of the  outfall (typically
       several hundred meters).
    *  Natural cycles of Codium growth have been reported in the literature prior to the
       discharge of wastewater effluent to the open ocean.
    •  The sporadic occurrences of the algal blooms are not consistent with the uniform
       discharge of the effluent, indicating no significant relationship.

The SEFLOE summary states that, "While the introduction of nitrogen into the marine
environment can have significant impacts on water quality and wildlife, in this case the
impacts to the open ocean appear to be mitigated by the vast reservoir of water available
for dilution, the speed with which dilution occurs due to the currents at the Floridian
outfalls, and the uptake and removal of nitrate by phytoplankton which entrains the
nitrogen into the food chain, thereby removing it from the area where it was first emitted.
The rapid dilution and removal of nitrate from the area immediately surrounding the boil
quickly decreases any measurable ecological risks associated with the discharge of nitrate
into the open ocean at the point where the effluent meets the receiving waters."

The stable isotopic composition of nitrogen in organic matter, called 615N, can be useful
in distinguishing the sources of organic matter and nutrients and the trophic level of the
organisms producing the organic matter (Hansson et al., 1997;  Peterson, 1999),
Wastewater nitrogen tends to be isotopically enriched in the heavier isotopes of nitrogen
relative to the atmospheric nitrogen standard, which represents a pristine source of
nitrogen. Sewage effluent nitrogen is often isotopically heavier (more positive numbers)
because of isotopic fractionation along the food chain that results in higher trophic levels,
producing isotopically heavier nitrogen in wastes (LaPointe,  1997; Densmore and
Bohlke, 2000; Rau et al.,  1981; Schroeder et al., 1993; Spies et al., 1981; Spies, 1984;
Van Dover et al., 1992). Wastewater nitrogen has been implicated as a source of
isotopically heavier nitrate in the Florida Keys (LaPointe, 1997). Carbon (813C) and sulfur
                                       6-35

-------
(832S) also provide useful isotopic tracers for organic matter (Fry et al., 1998; Gearing,
1988; Gearing et al., 1991; Wainwright and Fry, 1994; Peterson et al., 1996; Peterson,
1999).

LaPointe et al. (1992) suggests that phosphorus may be of greater importance than
nitrogen as a limiting nutrient in macroalgal growth in carbonate-rich tropical waters,
while nitrogen is more important in siliciclastic systems. More recently, work by
LaPointe (1997) found that, at four sites located between West Palm Beach and Kobe
Sound approximately 2 to 3 kilometers offshore, waters enriched with dissolved
inorganic nitrogen (DIN) increased the photosynthetic efficiency of Codium
isihmocladum in southeast Florida waters. In addition, elevated 615N values of C.
isthmocladum tissue indicated that waste water dissolved in DIN was a source of nitrogen
to blooms in southeast Florida. LaPointe found that increases in 815N values in Codium
tissue of more than 10 parts per thousand (o/od) occurred with the onset of the rainy
season, suggesting that discharges during the rainy season provided a significant nitrogen
source.

A different study of the fate of sewage effluent-derived nitrogen and carbon using stable
isotope tracers was conducted by researchers from EPA and Texas A&M University
(Hoch et al., 1995). This study examined suspended particulate organic matter, sediment
organic matter, filter-feeding organisms (sponges, soft, or gorgonian corals), settling
particle fluxes, and dissolved nutrients (ammonia, nitrate and nitrite, phosphorus, and
organic carbon) in the vicinity of the six southeast Florida ocean outfalls and one small
outfall located in the Florida Keys. The study hypothesized that pelagic  suspended
organic matter composed of phytoplankton is a source of organic matter to benthic
ecosystems and sediments and that the isotopic composition of these phytoplankton
sources (and the nutrients they utilize) would be reflected in the isotopic composition of
organic matter in sediments.

Hoch et al. (1995) found that sewage effluent ammonia from the southeast Florida
outfalls had 515Ns ranging from 4.4o/oo at the Central Miami-Dade outfall, to 8.60/00 at
Broward and 15.4o/oo at Key West. Sewage effluent DIN ranged from 4.3o/oo to 8.1o/oo
to 12.7o/oo, respectively. Nitrate and nitrite together had 615Ns ranging from -1.60/00 to -
5.7o/oo to 10.5o/oo, respectively. In comparison, suspended particulate organic matter
(including phytoplankton that take up nutrients) had 815Ns that were more negative than
effluent DIN and more similar to ambient marine organic matter (2o/oo to  4o/oo). This
suggests that the effluent plume nitrogen was being diluted with ambient marine
suspended particulate organic matter. In general, the nitrogen isotopic composition of
ammonia and DIN at the Central Miami-Dade  outfall was not very different from that of
ambient marine organic matter and DIN, while ammonia and DIN from the Broward
plant had isotopic signatures significantly different from that of ambient marine organic
matter.

The results for the six southeast Florida ocean outfalls indicated that phytoplankton
uptake of effluent-derived nitrogen into biota was not clearly demonstrated at any of the
southeast Florida outfalls, including the largest outfalls (Broward and Central Miami-
                                       6-36

-------
Dade). At these outfalls, there appears to be little coupling between the pelagic and
benthic ecosystems, even though loading of sewage effluent-derived nitrogen to coastal
environments was significant (about 6x10 kg of total N per year, of which more than 97
percent is derived from the six southeast Florida outfalls). Furthermore, the measured
rates of primary production were less than production estimated from the nitrogen load.
Hoch and colleagues concluded that the strong currents and rapid dilution at the southeast
Florida outfalls may have caused rapid dilution of sewage effluent nitrogen prior to
uptake by plankton. An alternate explanation for the observed isotopic values of organic
matter is that phytoplankton may have taken up a form of nitrogen not measured
isotopically (for example, organic nitrogen) (Hoch et al., 1995).

In contrast, the same study found that, at the Key West outfall, a conservative estimate of
the amount of effluent particulate carbon contributing to the diet of soft corals
immediately adjacent to the outfall is about 40%, based on the use of both carbon and
nitrogen stable isotopes. These different results suggest strongly that the physical
dispersion and dilution of effluent along the southeast Florida coast plays a major role in
reducing the ecological significance of effluent nitrogen. However, it also suggests that
the use of stable isotopes may not be an extremely sensitive tracer if the sewage effluent
isotopic composition is not significantly different from ambient marine organic matter to
begin with (Hoch et al., 1995).

6.6.2.3 Metals and Organic Compounds

As with nutrients, there are three basic questions concerning potential effects of metals
and organic priority pollutants remaining in effluent following secondary treatment:

    •  Are concentrations of priority pollutants in effluent or diluted effluent higher than
       water-quality standards for protection of ecological health?
    •  Can biological uptake of priority pollutants be demonstrated for any ecological
       component?
    •  Is there evidence of adverse effects because of exposure to or uptake of priority
       pollutants?

Metals

To address the question of whether metals in undiluted and diluted effluent meet water-
quality standards, the SEFLOE studies measured priority pollutant rnetals and detected
several (copper, arsenic, silver, lead) and cyanide in undiluted effluent.  Concentrations
sometimes exceeded Class III marine water-quality standards (Table 6-10). None of the
metals tested in undiluted effluent exceeded the Florida Maximum Allowable Effluent
Levels (Hazen and Sawyer, 1994).
                                       6-37

-------
Table 6-10.   Priority Pollutant Metals Detected in Treated Wastewater Effluent
               Exceeding Class III Marine Water-Quality Standards
Metal
Concentration in
Treated Effluent
(Hg/D
Background
Concentration
in Oceans8
(Mg/JL)
Florida
Maximum
Allowable
Effluent
Level
(Hfi/L)
Florida
Class III
Marine
Water
Standards
(Wfi/L)
EPA
Saltwater
Criteria
(MtfL)
Dilution
To Meet
Most
Stringen
t
Criteria
Broward
Arsenic,
total
Copper,
total
Lead,
total
Silver,
total
BDL, 124, <1,70, 2.3
2.1,20,111.3,14.4
BDL, 5.0, 4.8, 6.7
BDL, 0.5, 0.9, 0.5
1.77
0.261
0.0021
0.0028
N/A
N/A
<500
N/A
<50
£2.9
55.6
<0.05
36
2.9
8.5
N/A
3.6
42.1
1.2
19.0
Miami-Dade North
Arsenic,
total
Copper,
total
Lead,
total
Cyanide
0.83, BDL, <10.0C
19.0, 16.0, <10.0C
20.2, BDL, <5.0C
8.41, 8.0, <4.0C
1.77
0.261
0.0021
N/A
N/A
N/A
<500
N/A
<50
£2.9
£5.6
<1
36
2.9
8.5
1
N/A
7.1
3.6
8.41
Miami-Dade Central
Copper,
total
Lead,
total
Silver,
total
Cyanide
35,10
40, BDL
14d, BDL
9.6, BDL
0.261
0.0021
0.0028
N/A
N/A
<500
N/A
N/A
<2.9
£5.6
<0.05
£1
2.9
8.5
N/A
1
13.2
7.2
296.6
9.6
Note: Data are from Hazen and Sawyer, 1994, unless indicated otherwise by superscripts.
a   From Bruland. 1983.
b   Values shown in boldface represent the highest sample values. The dilutions to meet most stringent criteria are
    calculated in this report based on these highest sample values,
    Miami-Dade North District. 1999. See Appendix Table 1-2.
d   Questionable value, according to Hazen and Sawyer, 1994.
BDL    Below detection limits.
N/A Not available.
Note that with the possible exception of silver at the Miami-Dade Central plant (where
the value may be incorrect), the dilution required to meet the most stringent water quality
standard varies from 1.2 to 42, depending on the metal and the effluent concentration.
The 400 m to 800 m mixing zones required under the Florida regulations are intended to
provide dilutions ranging from 60:1 to 90:1 or more, based on modeling of the effluent
plume. Also, the concentrations of metals in effluent are measured in the parts per billion
range, which is low for industrial effluent.
                                          6-38

-------
 Both the regulatory criteria for Class III marine water and the effluent studies of South
 Florida ocean outfalls address total metals concentrations rather than dissolved metals.
 Since dissolved metals are the most bioavailable, they have the most potential to cause
 ecosystem toxicity effects. Therefore, the values in Table 6-10 can only be used for a
 general estimate of risks.

 The SEFLOE studies did not specifically report on biota in the vicinity of the outfalls,
 although Hazen and Sawyer (1994) report that a healthy ecosystem appeared to be
 present. Thus, there is no information concerning potential effects of metals or other
 stressors on benthic populations of organisms in the outfall areas.

 It is therefore not possible to answer the third question concerning evidence of adverse
 effects of priority pollutants on marine ecosystems in the area, but it is also not possible
 to rule out adverse effects. No long-term ecological monitoring studies of possible
 ecological effects were done following the conclusion of the SEFLOE studies in 1994.

 Volatile Organic Compounds

 Monitoring data were very limited for volatile organic compounds (VOCs); the only
 detected compound originates from the Miami-Dade Water Sewer North District, which
 reported a one-time measurement of tetrachloroethene of 4.66 ug/L on March 19,1999.
 The Florida Class III marine water-quality standard for tetrachloroethene is <8.85 ug/L
 on an annual average. Although the SEFLOE report sampled for  126 EPA priority
 pollutants, including tetrachloroethene and many other organic compounds, there were no
 other reported detections of tetrachloroethene.

 The one data point for VOC concentration in effluent is  less than the regulatory standard
 for VOCs in Class III marine waters, and it is less than the reported literature toxicity
 values (see Section II). VOCs are highly volatile and would be expected to volatilize as
 the effluent rises to the upper ocean layer. There is little or no evidence concerning VOCs
 in ecological receptors. Unfortunately, there are not enough data available to offer firm
 conclusions on this point. Again, while the effluent toxicity testing suggests that there is
 no short-term acute toxicity, there are no long-term ecological monitoring studies to
 examine long-term or cumulative ecological changes that might occur as a result of the
 discharge of effluent containing trace amounts of VOCs. Thus, for VOCs, the  small
 amount of data available from the SEFLOE report suggests that the amounts of VOCs
present in treated discharged effluent are very low and becomes even lower when rapid
 dilution by currents occurs. The toxicity testing indicates no toxic effects for chronic
 short-term testing or acute toxicity testing,

 Synthetic Organic Compounds

Very little data were available concerning linear alkylbenzenesulfonates (a detergent
component used as a representative detergent compound in this study) in Florida
wastewater effluent. Effluent data from the Miami-Dade North District detected a
concentration of methylene blue anionic surfactant (MBAS) surfactant of 0.063 mg/L in
                                       6-39

-------
the effluent prior to discharge (Table 6-11 from Hazen and Sawyer, 1999). This
concentration is lower than the regulated Class III standard of <0.5 mg/L for detergents.
More information on occurrence and levels of surfactants in treated effluent and in
receiving waters and their biological effects is needed to adequately evaluate ecological
risks posed by this category of compound.

Table 6-11.   MB AS Concentrations in Effluent and Calculated Dilution
              Concentration at 400 m from the Boil

MBAS
surfactant
MBAS in
Effluent
(mg/L)
0.063 '
MBAS in
Effluent
(mg/L),
60:1 Dilution
0.001
MBAS in
Effluent
(mg/L),
90:1 Dilution
0.0007
Background
Seawater
(mg/L)
0
Class III
Standard for
Detergents
(mg/L)
<0.5
1 Data from Miami-Dade Water/Sewer, North District. 1999. Submission #9903001041, pp. 47-52. Screen effluent
collected 3/19/99.
No information is available on monitoring of detergents or other synthetic organic
compounds in ecological receptors at or near the effluent outfall.

Hormonallv Active Agents

Estrogen equivalences were measured from two grab samples at the Gulfgate and
Southgate treatment plants in Sarasota, Florida. Both of these plants treat to advanced
wastewater treatment levels and discharge to surface-water creeks. The average
concentration of estrogen substances in the treated wastewater effluent was 3.253
nanograms per liter (Frederic Bloettscher, Consulting Professional Engineer, personal
communication). At this point, this information only indicates that these substances may
be present in treated wastewater effluent intended for discharge into surface water. The
literature suggests that, while these concentrations may not induce toxic effects in aquatic
organisms, more study is needed concerning the concentrations at which endocrine
disruption may occur because of biodegradation byproducts.

No information is available concerning concentrations of estrogen-like compounds in
ambient seawater at the southeast Florida ocean outfall sites, nor in ecological receptors
at or near the ocean outfall sites. Ongoing and future research should provide a better
framework for discussing these compounds and evaluating their risks.  Having monitoring
data for these constituents in effluent would allow risk to be better evaluated.

6.6.2.4 Toxicity Testing of Effluent

One way to address the question of whether there could be adverse effects from effluent
is to conduct toxicity testing of effluent using marine organisms. In order to comply with
Florida standards, biological toxicity testing of the diluted and undiluted treated effluent
was conducted as part of the SEFLOE studies (Commons et al., 1994a, 1994b) and is
                                       6-40

-------
summarized in the Hazen and Sawyer (1994) report. A total of 1,727 acute bioassay
toxicity tests and 109 short-term chronic bioassays were performed, using diluted effluent
water from four ocean outfall wastewater treatment plants and effluent plume samples.
Acute toxicity was assessed using the mysid shrimp Mysidopsis bahia and the estuarine
fish Menidia beryllina. Short-term chronic toxicity testing was assessed using those
organisms, the sea urchin Arbaciapunctulata, and the macroalga Champia parvula. The
bioassay results were compared with current velocities to determine initial and farfield
dilutions and to calculate actual exposure times. This allowed researchers to determine
potential toxicity of the undiluted effluent, initial dilution, and mixing-zone
effluent/seawater mixture.

In all ocean bioassay tests, no potential acute toxicity of effluent or diluted effluent was
demonstrated. The bioassay s are believed to be conservative: during the tests using
diluted effluent, organisms  are exposed to the effluent longer and at concentrations that
greatly exceed actual measured concentrations of effluent constituents in the ocean
outfall area (Commons et al.,  1994a, 1994b; Hazen  and Sawyer, 1994).

While toxicity testing indicates that there are no acute toxic effects to biological
organisms, long-term low-dose chronic toxicity testing was not conducted. Toxicity
testing also does not address effects  of nutrient enrichment on ecological processes of
production, organic cycling, or microhabitats where nutrients may remain more
concentrated. Ecological processes that are not addressed by toxicity testing include
nutrient-stimulated primary production and respiration, production of organic  matter for
consumers and detrital feeders, decomposition of organic matter, and the effects of these
processes on water quality and biological communities.

6.6.3   Final Conceptual Model of Probable Risk for Ocean Outfalls

The SEFLOE studies provide a risk assessment and a prediction that there should not be
any adverse effects resulting from ocean discharge of secondary-treated effluent. This
prediction is based largely on the rapid dispersal and dilution of the effluent plumes by
the Florida Current and that the treated effluent has  relatively low concentrations of
stressors to begin with. Prevailing current directions and fast current speeds of the Florida
Current are major factors that decrease risk for the six ocean outfalls that discharge into
the Florida Current. Current speeds can be more than 60 or 70 cm/sec for the Florida
Current, while speeds of 20 to 40 cm/sec commonly occur. Northerly flow with the
fastest speeds occurs approximately  60% of time. Southerly flow with similar or lesser
speeds occurs about 30% of time. Flow in other directions (easterly, westerly) exhibits
the lowest current speeds and occurs less than 10% of the time. Westerly flow towards
the east coast of Florida, which represents the highest risk, is estimated to occur less than
approximately 4% of the time, while easterly flow is estimated to occur less than
approximately 6% of the time.

Other factors that decrease risk are the distance of the outfalls from land. The lowest risk
outfalls are farthest from land (Miami-Dade Central outfall), while the highest risk
outfalls are closest to land (Boca Raton, Del Ray Beach). The use of multiport difrusers,
                                       6-41

-------
compared to the use of single-port diffusers, appears to aid in dispersal of the effluent
plume over a wider area, decreasing potential risk. Discharging the effluent at a faster
initial speed also appears to increase the rate  of dispersal and dilution of the effluent
plume.

Based on toxicity testing of marine organisms, there is no evidence that the diluted
effluent causes acute toxic effects or short-term chronic effects.

Based on nitrogen isotope studies of organic matter in sediments and nutrients in the
water column, it does not appear that the nitrogen in outfall effluent is taken up in
significant amounts by phytoplankton in the area. This may be because of the rapid
dilution of the effluent nitrogen by the Florida Current.

The state of Florida requires that Class III water quality standards be met outside a
mixing zone of 502,655  m2 around the outfall. This mixing zone allows for dispersal,
mixing, and dilution of the effluent plume. A mixing zone with a circular radius of 400 m
measured from the outfall was used by the utilities in the SEFLOE study. This circle
would cover an area equivalent to 502,655 m2. The use of a circular mixing zone is not
required by Florida, but  is used for ease of defining an area to monitor.

Concentrations of pathogens are controlled at the treatment plant through chlorination to
meet water-quality standards within the required mixing zone; viruses and most bacteria
are expected to be adequately inactivated by chlorine. However, there  is no filtration to
remove Cryptosporidium and Giardia. Lack of treatment to remove pathogenic
protozoans probably constitutes the greatest human health risk posed by this wastewater
management option.

Pathogenic protozoans may also pose significant ecological risks related to infections of
marine mammals. The effects of pathogenic protozoans on aquatic organisms need to be
further investigated.

Concentrations of priority pollutant metals in undiluted effluent may exceed marine
water-quality standards (but meet effluent standards), but there is no information on
actual receptors or exposure pathways because there were no benthic tissue monitoring
studies, benthic ecology studies, or studies of trace metals in the water column as part of
the SEFLOE studies. The results of the SEFLOE study for metals monitoring indicates
that, in general, water-quality standards are met at 400 m or 800 m.

In coastal areas from North Carolina south to Florida, oysters, other shellfish, and
sediments have elevated concentrations of arsenic, although not at levels that would pose
a threat to humans or to marine life, according to a NOAA National  Status and Trends
Program report (Valette-Silver et al., 1999). Postulated sources of arsenic include
pesticides, mining of arsenic-containing phosphate rocks, atmospheric dust, river and
groundwater inputs, and ocean upwelling. The NOAA study did not examine ocean
outfalls as potential sources of metals. Since oysters are a nearshore intertidal species, it
                                       6-42

-------
 is most likely that the arsenic is derived from terrestrial and coastal sources close at hand,
 rather than the ocean outfalls.

 Concentrations of priority pollutant organic compounds in treated wastewater are
 generally very low. Monitoring data were very limited for volatile organic compounds;
 the only data available originates from the Miami-Dade Water Sewer North District,
 which reported a one time measurement of tetrachloroethene of 4.66 U£/L, which meets
 the Florida Class III annual average marine water-quality standard for tetrachloroethene
 of <8.85 ug/L. There were no reported detections of tetrachloroethene in the SEFLOE
 study.

 Concentration of a surfactant, MB AS, of 0.063 mg/L in the effluent is lower than the
 regulated Class III standard for detergents of <0.5 mg/L. The effects of low
 concentrations of surfactants on aquatic organisms in natural settings are not well
 understood or documented. The lack of knowledge concerning effects of surfactants on
 the tissues and physiologic functions of aquatic organisms is not cause to eliminate this as
 a potential stressor. Surfactants act to decrease surface tension and reduce adhesion,
 which may affect microorganisms or for other functions in higher organisms.

 Despite the lack of information on effects of endocrine disrupters in South Florida marine
 waters, effluent discharged to marine waters typically contains such compounds.
 Endocrine disruptors may pose a concern because they can cause effects in aquatic
 organisms at very low concentrations and because they are typically present in
 wastewater and not removed by existing wastewater treatment technology. However,
 better information on the concentrations of these substances in Florida wastewater,
 coastal waters, and in aquatic organisms is needed. A better understanding of their effects
 is also needed.

 In summary, the chlorinated discharged effluent largely meets Class III water-quality
 standards for all regulated wastewater constituents within 400 m of the outfalls, with
 exceptions as noted.

 The lack of long-term ecological, microbial pathogen, and chemical monitoring studies
 makes it difficult to evaluate whether the conclusions of the SEFLOE studies will
 continue to hold true in the future. It is not possible to evaluate whether long-term,
 cumulative, chronic risks exist or not. There are no ongoing monitoring studies
 downcurrent of any of the effluent plumes or within the footprint of the effluent plume.
An initial project to formulate a long-term study to address issues concerning nutrients,
 growth of nuisance macroalgae (Codiwri), productivity, and the benthic community had
begun in the early 1990s, but this project did not go forward at that time. A long-term
 extensive  program is now being contemplated that will examine long-term monitoring of
the outfalls and adjacent areas and examine sources of nutrient loading (personal
communication, John Proni).

Potential long-term ecological risks may exist, particularly within the 400-m mixing
zone, but also outside it. Nutrients, including both nitrogen and phosphorus, may
                                       6-43

-------
constitute the most important ecological stressors resulting from ocean outfalls. Nutrient
dispersal poses concerns because coastal water quality throughout Florida is already
impacted by a variety of human activities on land, such as agriculture, septic systems,
urbanization, and channelization of wetlands. The cumulative ecological risks associated
with continually discharging nutrients into the Florida Current, and ultimately the Gulf
Stream, are not known. The same is true of other effluent constituents, such as metals and
organic compounds.

Information needed to assess whether or not there is a long-term, chronic, or cumulative
adverse effect on marine organisms would include the following:

    *   Monitoring of benthic communities in the plume track and adjacent areas
    •   Tissue studies of bioaccumulation in the food chain
    •   Monitoring of primary production and nutrient uptake and cycling
    •   Tracer studies of the sources of nitrogen and phosphorus being utilized by
       phytoplankton
    •   Marine particle fluxes of metals in the plume track and adjacent areas to
       determine whether metals discharged in the effluent adsorb onto marine snow
       particles or precipitate as solid particles or not
    •   Related studies of the ecology and chemistry of the ocean within the plume
       footprint and adjacent to it.

Human health risks are of some concern, both within the 400-m mixing zone and outside
of it, primarily because treatment of effluent prior to discharge via ocean outfalls does not
include filtration to remove Cryptosporidium and Giardia, The most probable human
exposure pathways include fishermen, swimmers, and boaters who venture out into the
Florida Current and experience direct contact, accidental ingestion of water, or ingest fish
or shellfish exposed to effluent. Otherwise, there is a very small, but not nonzero, chance
for onshore or nearshore recreational or occupational users to be exposed to effluent
constituents, since there is a small (10%) chance that currents will change direction to
east or west.

Finally, there is the question  of whether any adverse effects, if they exist, are reversible.
Monitoring studies of Tampa Bay, where tertiary treatment of effluent is now required
instead of secondary treatment (see Chapter 7, Surface Water Discharge) indicates that
water quality and benthic ecological conditions will improve upon upgrading treatment
(Lipp et al., 2001). Even at highly affected marine disposal sites where sewage sludge has
been disposed of, cessation of disposal has resulted in improvement of the benthic
communities and water and sediment quality (Studholme et al., 1995, 1989). Because the
existing southeast Florida ocean outfalls discharge to the Florida Current, recovery from
any adverse effects, if they exist, would probably be rapid because of the rapid flushing
by the Florida Current.
                                       6-44

-------
6.7    Potential Effects of Data Gaps

Because of the relatively short term of the SEFLOE studies (several years), the long term
or cumulative ecological risks of nutrient loading and loading of other effluent
constituents cannot be evaluated. Some of the specific questions that cannot be answered
at this time include:

    •   Effects of adding nitrogen and phosphorus to the Gulf Stream nutrient budget and
       its potential to affect primary productivity in the open ocean
    •   Effects on productivity and marine organisms within the plume where nutrient
       concentrations are higher than background concentrations
    •   Potential changes in the ratio of nitrogen to phosphorus and effects on
       phytoplankton diversity
    •   Frequency of harmful algal blooms in the vicinity of the outfalls
    •   Bioaccumulation of effluent constituents by marine organisms in the vicinity of
       the outfall and its plume footprint
    •   Changes in trophic structure and potential food-web effects
    •   Effect of global climate change or other factors on the Florida Current that would
       cause changes in current speed, direction, or position and affect dilution of the
       effluent plume, affecting risk
    *   Long-term, chronic effects of exposure of benthic or nektonic marine organisms
       to effluent constituents in the vicinity of the effluent plume.

Regarding potential human health risk issues, there are also significant data gaps. Some
examples of questions that remain unanswered include the following:

    •   Are Cryptosporidium and Giardia present in nearshore waters that are used by
       humans, are their concentrations within  safe limits, and if not can their sources be
       determined (for example, onshore sources versus ocean outfalls)?
    •   Are pathogenic E. coii, enteric viruses, and other enteric pathogens present in the
       treated effluent in numbers high enough to be of concern for human health?
    •   What is the relative contribution of enteric pathogens and other stressors from
       existing onsite septic disposal systems and other sources versus ocean outfalls to
       water quality near the outfalls?

These are just a few of the issues that remain to be addressed if long-term risk from ocean
outfalls is  to be fully assessed.
                                       6-45

-------
REFERENCES

Alevizon W. 1994. Pisces Guide to Caribbean Reef Ecology. Houston (TX): Pisces
       Books.

Atkinson LP. 1985. Hydrography and nutrients of the Southeastern U.S. continental shelf.
       In: Oceanography of the Southeastern U.S. Continental Shelf, Atkinson LP,
       Menzel DW, and Bush KA, eds. Washington (DC): American Geophysical
       Union.

Billen G, Lancelot C, and Meybeck M. 1991. Nitrogen, phosphorus, and silicon retention
       along the aquatic continuum from land to ocean. In: Ocean Margin Process in
       Global Change. Mantoura RFC, Martin JM, and Wollast R, eds. New York:
       Wiley.

Bowen JL, Dow D, Serveiss V, Valiela I, Tyler P, and Geist M. 2001. Waquoit Bay
       Watershed Ecological Risk Assessment. Washington (DC): National Center for
       Environmental Assessment, Office of Research and Development, US EPA.

Bruland KW. 1983. Trace elements in sea water. In: Vol. 8 Chemical Oceanography,
       Riley JP and Chester R, eds. London: Academic Press.

Burnett WC and Schaeffer OA. 1980. Effect of ocean dumping on 13C/12C ratios in
       marine sediments from the New York Bight. Estuarine and Coastal Marine
       Science. 11:605-611.

CarmichaelP and Williams W. 1991. Florida's Fabulous Reptiles And Amphibians.
       Singapore: World Publications.

Carmichael WW. 1994. The toxins of cyanobacteria. Scientific America. 270:64-72.

Carpenter EJ and Romans K. 1991. Major role of the cyanobacterium Trichodesmium in
       nutrient cycling in the North Atlantic Ocean. Science. 254:1356-1358.

Codispoti LA. 1989. Phosphorus vs. nitrogen limitations of new and export production.
       In: Productivity of the Ocean: Present and Past. Berger WH, Smetacek V, and
       Wefer G, eds. New York: Wiley.

Commons DN, Proni JR, Huang H, Dammann WP, Goldenberg BM, Monson JG, and
       Fergen RE. 1994a. Coastal oceanographic characteristics and their impact on
       marine biotoxicity studies during the SEFLOE II. Abstract in: Fourth
       Environmental Toxicology and Risk Assessment Symposium',  1994 April 11;
       Montreal, Quebec, Canada. West Conshohocken (PA): American Society  for
       Testing and Materials.
                                     6-46

-------
Commons DN, Proni JR, and Fergen R. 1994b. Real world toxicity testing of an open
       ocean discharge. Abstract in: 66th Annual Conference and Exposition, Surface
       Water Quality and Ecology, 1993 October 3-7; Anaheim, CA. Alexandria (VA):
       Water Environment Federation.

Corredor JE, Howarth RW, Twilley RR, and Morrell JM. 1999. Nitrogen cycling and
       anthropogenic impact in the tropical interamerican seas. Biogeochemistry.
       46(1/3): 163-178.

Cotner J, Ammerman J, Peele E, and Bentzen E.  1997. Phosphorus-limited
       bacterioplankton growth in the Sargasso Sea. Aquatic Microbiology & Ecology.
       13:141-149.

Densmore JN and Bohlke JK. 2000. Use of nitrogen isotopes to determine sources of
       nitrate contamination in two desert basins in California. Abstract in:
       Interdisciplinary Perspectives on Drinking Water Risk Assessment and
       Management. International Association of Hydrological Sciences (IAHS)
       Publication No. 260:63-73.  Oxfordshire (UK): IAHS.

Dugdale RC. 1967. Nutrient limitation in the seas: dynamics, identification, and
       significance.  Limnology & Oceanography. 12:685-695.

Englehardt JD, Amy VP, Bloetscher F, Chin DA, Fleming LE, Gokgoz S, Rose JB, Solo-
       Gabriele H, and Tchobanoglous G. 2001. Comparative Assessment of Human and
       Ecological Impacts from Municipal Wastewater Disposal Methods in Southeast
       Florida. Submitted to the Florida Water Environment Association Utility Council.

Edler L, Ferno S, Lind MG, Lundberg R, and Nilsson PO. 1985. Mass  mortality of dogs
       associated with a bloom of the cyanobacterium Nodularia spumigena in the Baltic
       Sea. Ophelia. 2:103-109.

Feacham RG, Bradley DH, Garelick H, and Mara DD. 1983. Sanitation and Disease
       Health Aspects of Excreta and Wastewater Management. New York: Wiley.

Finney BB and Huh CA.  1989. History of metal pollution in the Southern California
       Bight: an update. Environmental Science &  Technology. 23:294-303.

Flegal AR, Sanudo-Wilhelmy SA, and Scelfo GM.  1995. Silver in the eastern Atlantic
       Ocean. Marine Chemistry. 49:315-320.

[FFWCC] Florida Fish and Wildlife Conservation Commission. 1997. Florida's
       Endangered Species Threatened Species and Species of Concern. Internet:
       http://floridaconservation.org/pubs/endanger.html.

           . 2001. Florida Marine Research Insitute. Internet:
      http://www.floridamarine.org.
                                     6-47

-------
           _. 2002a. Shellfish Poisoning. Internet http://www.floridamarine.org/features/
       category_sub.asp?id=1850. Accessed 12 February 2002.

	. 2002b. HAB Species. Internet: http://www,floridamarine.org/features/
       category_sub.asp?id=1816. Accessed 12 February 2002.

Forstner U and Wittmann GTW. 1979. Metal Pollution in the Aquatic Environment.
       Berlin: Springer.

Fry B, Hopkinson Jr. CS, Nolin A, and Wainwright SC. 1998. 13C/12C composition of
       marine dissolved organic carbon. Chemical Geology. 152:113-118.

Gearing JN. 1988. The use of stable isotope ratios for tracing the nearshore-offshore
       exchange of organic matter. In: Coastal-Offshore Ecosystem Interactions. Jansson
       BO, ed. Berlin: Springer Verlag.

Gearing PJ, Gearing JN, Maughan JT, and OvJatt CA.  1991. Isotopic  distribution of
       carbon from sewage sludge and eutrophication in the sediments and food web of
       estuarine ecosystems. Environmental Science and Technology. 25: 295-301.

Geldreich EE. 1978. Bacterial populations and indicator concepts in feces, sewage,
       stormwater  and solid wastes. In: Indicators of Viruses in Water and Food. Berg
       G, ed. Ann Arbor (MI): Ann Arbor Science.

Griffin DW, Gibson III CJ, Lipp EK,  Riley K, Paul JH and Rose JB. 1999. Detection of
       viral pathogens by reverse transcriptase PR and of microbial indicators by
       standard methods in the canals of the Florida Keys. Applied Environmental
       Microbiology. 65:4118-4125.

Hansson S, Hobbie JE, Elmgren R, Larsson U, Fry B, and Johansson  S. 1997. The stable
       nitrogen isotope ratio as a marker of food-web interactions and fish migration.
       Ecology. 78(7):2249-2257.

Hazen and Sawyer. 1994. SEFLOEII Final Report: Broward County Office of
       Environmental Services North Regional Wastewater Treatment Plant; City of
       Hollywood Utilities Department Southern Region Wastewater Treatment Plant;
       Miami-Dade Water and Sewer Department North District Wastewater Treatment
       Plant; Miami-Date Water and Sewer Department Central District Wastewater
       Treatment Plant. Hollywood (FL): Ha/en and Sawyer. Submitted to National
       Oceanic and Atmospheric Administration.

Hershelman GP, Schafer HA, Jan TK, and Young  DR. 1981. Metals in marine sediments
       near a large California municipal outfall. Pollution Bulletin. 12:131-134.
                                      6-48

-------
Hoch MP, Cifuentes LA, and Coffin R. 1995. Assessing Geochemical and Biological
       Fate for Point Source Loads of Sewage-Derived Nitrogen and Organic Carbon in
       Coastal Waters of Southern Florida. Final Report to US EPA.

Holland HD. 1978. The Chemistry of the Atmosphere and Oceans. New York: Wiley
       Inter science.

Honjo S, Mangani S, and Cole J. 1982. Sedimentation of biogenic matter in the deep
       ocean. Deep Sea Research. 29(5A):609-625.

Howarth RW. 1988. Nutrient limitation of net primary production in marine ecosystems.
       Annual Review of Ecology. 19:89-110.

Howarth RW, Jensen HS, Marino R, and Postma H. 1995. Transport to and processing of
       phosphorus in nearshore and oceanic waters. In: Phosphorus in the Global
       Environment, Tiessen, H ed. New York: Wiley.

Huang H, Proni JR, and Tsai JJ. 1994.  Probabilistic approach to initial dilution of ocean
       outfalls. Water Environment Research. 66(6):787-793.

Huang H, Fergen RE, Tsai JJ and Proni JR. 1998. Evaluation of mixing zone models:
       CORMIX, PLUMES, and OMZA with field data from two Florida ocean outfalls.
       In: Environmental Hydraulics.

Huh CA, Finney BP, and Stull  JK. 1992. Anthropogenic inputs of several heavy metals to
       nearshore basins off Los Angeles. Progress & Oceanography. 30:335-351.

Huntzicker JJ, Friedlander SK, and Davidson  CI. 1975. Material balance for automobile-
       emitted lead in Los Angeles Basin. Environmental Science Technology 9:448-457.

Johns E, Wilson WD, and Molinari RL. 1999. Direct observations of velocity and
       transport in  the passages between the Intra-Americas Sea and the Atlantic Ocean,
       1984- 1996. Journal of Geophysical Research. 104(C11): 25,805-25,820.

Klein HH and Goldberg ED. 1970. Mercury in the marine environment. Environmental
       Science Technology. 4:765-768.

LaPointe BE. 1997. Nutrient thresholds for bottom-up control of macroalgaf blooms on
       coral reefs in Jamaica and southeast Florida. Limnology & Oceanography. 42(5
       part 2): 1119-1131.

LaPointe BE, Littler M, and Littler D. 1992. Nutrient availability to marine macroalgae in
       siliciclastic versus carbonate-rich coastal waters. Estuaries, 15(1): 75-82.

Lee TN. 1975. Florida current spin-off eddies. Deep Sea Research. 22:753-765.
                                     6-49

-------
Lee TN and Mayer DA. 1977. Low-frequency current variability and spin-off eddies
       along the shelf off southeast Florida. Journal of Marine Research. 35:193-220.

Lee TN, Rooth C, Williams E, McGowan M,  Szmant AF, and Clarke ME. 1992.
       Influence of Florida Current, gyres and wind-driven circulation on transport of
       larvae and recruitment in the Florida Keys coral reefs. Continental Shelf
       Research.  12(7/8):97i-1002.

Lee TN, Leaman K, and Williams E. 1995. Florida Current meanders and gyre formation
       in the southern Straits of Florida. Journal of Geophysical Research.
       100(C5):8607-8620.

Lipp EK, Farrah SA, and Rose JB. 2001. Assessment and impact of microbial fecal
       pollution and human enteric pathogens in a coastal community. Marine Pollution
       Bulletin. 42:286-293.

Malone TC, Conley DJ, Fisher TF, Gilbert PM, Harding LW, and Sellner KG. 1996.
       Scales of nutrient-limited phytoplankton productivity. Chesapeake Bay.  Estuaries.
       19:371-385.

Marella RL. 1999. Water withdrawals, use, discharge, and trends in Florida, 1995. USGS
       Water Resources Investigations Report 99-4002. Talahassee (FL): USGS in
       cooperation with the Florida  Department of Environmental Protection.

Matthai C and Birch GF. 2000. Trace metals and organochlorines in sediments near a
       major ocean outfall on a high energy continental margin (Sydney, Australia).
       Environmental Pollution. 110:411-423.

Morel FMM, Westphal JC, O'Melia CR, and Morgan JJ. 1975. Fate of trace metals in
       Los Angeles County wastewater discharge. Environmental Science & Technology.
       9:756-761.

Myers VB and Iverson RL 1981. Phosphorus and nitrogen limited phytoplankton
       productivity in northeastern Gulf of Mexico coastal estuaries. In: Estuaries and
       Nutrients. Nielson GJ and Cronin LE, eds. New York: Humana Press.

National Academy of Sciences.  1984. Disposal of Industrial and Domestic  Wastes: Land
       and Sea Alternatives. Report of the Panel  on Marine Sciences. Commission on
       Physical Sciences, Mathematics and Applications.

National Research Council. 2000.  Clean Coastal Waters: Understanding and Reducing
       the Effects of Nutrient Pollution. Washington(DC): National Academy Press.

Nehring S.  1993. Mortality of dogs associated with mass development of Nodularia
       spumigena (Cyanophyceae) in a brackish  lake at the German North Sea coast.
       Journal of Plankton Research.  15:867-872.
                                      6-50

-------
[NOAA] National Oceanic and Atmospheric Administration. 2002a. AOML Web site.
       Internet: http://www.aoml.noaa.gov/general/project/oadall lpl.jpg.

	. 2002b. State of the Coastal Environment: Harmful Algal Blooms. Internet:
       http://state-of-coast.noaa.gov/bulletins/html/hab_14/hab.html.

      	. 2002c. State of the Coastal Environment: The Extent and Condition of U.S.
       Coral Reefs. Internet: http://state-of-coast.noaa.gov/bulletins/html/crf_08/
       case.html.
Paerl HW. 1997. Coastal eutrophication and harmful algal looms: importance of
       atmospheric deposition and groundwater as "new" nitrogen and other nutrient
       sources. Limnology & Oceanography, 42(5 part 2): 1154-1165.

Parsons TR, Takahashi M, and Hargrave B. 1984. Biological Oceanographic Processes.
       3rd ed. New York: Pergamon Press.

Paul JH, Rose JB, Brown J, Shinn E, Miller S, and Farrah S. 1995. Viral tracer studies
       indicate contamination of marine waters by sewage disposal practices in Key
       Largo, Florida. Applied and Environmental Microbiology. 61:2230-2234.

Paul JH, Rose JB, Jiang S, Zhou X, Cochran P, Kellogg C, Kang JB, Griffin D, Farah S,
       and Lukasik J. 1997. Evidence for groundwater and surface marine water
       contamination by waste disposal wells in the Florida Keys. Water Research.
       31:1448-1454.

Peterson BJ. 1999. Stable isotopes as tracers of organic matter input and transfer in
       benthic food webs: A review. Academia Oecologia. 20:479-487.

Peterson BJ, Fry B, Saupe S, and Hullar MH. 1996. The distribution and stable carbon
       isotopic composition of dissolved organic carbon in estuaries.  Estuaries. 17:111-
       121.

Pilskaln and Honjo. 1987. The fecal pellet fraction of biogeochemical particle fluxes to
       the deep sea. Global Biogeochemistry Cycles. 1:31-48.

Proni JR. 2000. Using acoustical methods to study and monitor the discharge of sewage
       and dredged material in the coastal ocean. Abstract in: Vol. 1.  Proceedings, Fifth
       European Conference on Underwater Acoustics (ECUA 2000); 2000 July 13-13;
       Lyon, France. European Acoustics Association.

Proni JR and Dammann WP. 1989. Observations of acoustic backscatter from oceanic
       wastewater outfalls. Abstract in: Journal of the Acoustical Society of America.
       85:S42.
                                      6-51

-------
Proni JR, Dammann WP, Craynock JF, Stamates SJ, Commons D, Fergen R, Huang H,
       Ferry R, Goldenberg B, Mandrup-Poulson J, Monson J, and Williams R. 1996.
       Worst case effluent discharge conditions and adaptive processing of effluents for
       southeast Florida outfalls. Abstract, in Proceedings, 68th Annual Conference,
       WEFTEC '95; 1995 October 21-25; Miami Beach, Florida. Alexandria (VA):
       Water Environment Federation.

Proni JR, Huang H, and Dammann WP. 1994. Initial dilution of southeast Florida ocean
       outfalls. Abstract in: Journal of Hydraulic Engineering, 120:1409-1425.

Proni JR. and Williams RG. 1997. Acoustic measurements of currents and effluent plume
       dilutions in the western edge of the Florida Current. Abstract in: Acoustic Remote
       Sensing Applications. Singal SP ed. New Delhi (India): Narosa Publishing House.

Rabalais NN, Turner RE, Justic D, Dortch Q, and Wiseman Jr. WJ. 1999.
       Characterization ofHypoxia; Topic, Report for the Integrated Assessment of
       Hypoxia in the Gulf of Mexico, NOAA Coastal Ocean Program. Decision
       Analysis Series No. 15. Silver Spring (MD): NOAA Coastal Ocean Program.

Rau GH, Sweeney RE, Kaplan IR, Mearns AJ, and Young DR. 1981. Differences in
       animal 13C and 15N and deuterium abundance between a polluted and unpolluted
       coastal site as likely indicators of sewage uptake by a marine food web. Estuarine
       and Coastal Shelf Science. 13: 701-708.

Ravizza GE and Bothner MH. 1996, Osmium isotopes and silver as tracers of
       anthropogenic metals in sediments from Massachusetts and Cape Cod Bays.
       Geochimica Cosmochimica Acta. 60:2753-2763.

Rose JB and Carnahan RP. 1992. Pathogen Removal By Full Scale Wastewater
       Treatment, A report to the Florida Department of Environmental Protection.
       Tampa: University of South Florida.

Ruttenberg KC. 1993. Reassessment of the oceanic residence time of phosphorus.
       Chemical Geology. 107:405-409.

Ryther JH and Dunstan WM. 1971.  Nitrogen, phosphorus and eutrophication in the
       coastal marine environment. Science. 171:1008-1112.

Science Coordination Team and the Science Program for Florida Bay and Adjacent
       Marine Systems. 2001. South Florida Ecosystem Restoration: Scientific
       Information Needs in the Southern Coastal Areas: Progress and Update,
       February, 2001.

Schmitz W and Richardson PL. 1991. On the sources of the Florida Current. Deep Sea
       Research. 38(suppl. 1):5379-5409.
                                     6-52

-------
Schroeder RA, Martin P, and Bohlke JK. 1993. Chemical, Isotopic, And Microbiological
       Evidence For Denitriflcation During Transport Of Domestic Waste-water Through
       A Thick Unsaturated Zone In The Mojave Desert, San Bernardino County,
       California, USGS Open File Report 933-414. Washington (DC): USGS.

Sellner KG. 1997. Physiology, ecology, and toxic properties of marine cyanobacteria
       blooms. Limnology & Oceanography. 42(5) part 2:1089-1104.

Smayda TJ. 1997. Harmful algal blooms: Their ecophysiology and general relevance to
       phytoplankton blooms in the sea. Limnology & Oceanography. 42(5 part 2): 1137-
       1153.

Smith SB. 1984. Phosphorus vs. nitrogen limitation in the marine environment.
       Limnology & Oceanography. 29:1149-1160.

Spies R. 1984. Benthic-pelagic coupling in sewage-affected marine ecosystems. Marine
       Environmental Research. 13: 195-230.

Spies RB, Kruger H, Ireland R, and Rice Jr. DW. 1989. Stable isotope ratios and
       contaminant concentration in a sewage-distorted food web. Marine Ecological
       Progress Series. 54: 157-170.

[USFWS] United States Fish and Wildlife Service. 1999. 50 CFR 17 Endangered and
       Threatened Wildlife and Plants. Internet: http://endangered.fws.gov/
       50cfr_animals.pdf.

Valette-Silver NJ, Riedel GF, Crecelius EA, Windom H, Smith RG and Dolvin SS. 1999.
       Elevated arsenic concentrations in bivalves from the southeast coasts of the USA.
       Marine Environmental Research. 48:311-333.

Van Dover CL, Grassle JF, Fry B, Garritt RH, and Starczak VR.  1992. Stable isotope
       evidence for entry of sewage-derived organic material into a deep-sea food web.
       Nature,36Q: 153-156.

Wainwright SC and Fry B. 1994. Seasonal variation of the stable isotopic compositions
       of coastal marine plankton from Woods Hole, MA, USA and Georges Bank.
       Estuaries. 17:552-560.

Wang J, and Mooers CNK. 1997. Three-dimensional perspectives of the Florida Current:
       transport, potential vorticity, and related dynamical properties. Dynamics of
       Atmospheres and Oceans. 27: 135-149.

Williams W. 1983. Florida's Fabulous Waterbirds: Their Stories. Singapore: National Art
       Services, Inc.
                                     6-53

-------
Williams RG and Proni JR. 1994. Acoustic remote sensing of wastewater outflow.
      Abstract in: Proceedings, Vols, 1-43 and 1-49. Seventh International Symposium
      on Acoustic Remote Sensing and Associated Technologies of the Atmosphere and
      Oceans', 1994 October 4; Boulder, CO. Boundary Layer Meteorology.

Wood IR, Bell RG and Wilkinson DL. 1993. Ocean Disposal of Wastewater. In: Vol. 8.
      Advanced Series on Ocean Engineering. New Jersey: World Scientific.

York DW, Menendez P, and Walker-Coleman L. 2002. Pathogens in reclaimed water: the
      Florida experience. 2002 Water Sources Conference,

Zdanowicz V, Leftwich S, Finneran T, and Leimburg E. 1991. Sediment trace metals. In:
      Response of the Habitat and Biota of the Inner New York Bight to Abatement of
      Sewage Sludge Dumping, Third Annual Progress Report - 1989. Studholme AL,
      Ingham MC, and Pacheco A, eds. NOAA Technical Memorandum NMFS-
      F/NEC-82. Silver Spring (MD) NOAA.

Zdanowicz V, Cunneff SL, and Finneran TW. 1995. Reductions in sediment metal
      contamination in the New York Bight Apex with the cessation of sewage sludge
      dumping. In: Effects of the Cessation of Sewage Sludge Dumping at the 12-Mile
      Site, 12-Mile Dumpsite Symposium, Long Branch, New Jersey, June 1991,
      Studholme, AL, O'Reilly JE, and Ingham MC, eds. NOAA technical Report
      NMFS 124, pp.89-100. Silver Spring (MD): NOAA.
                                    6-54

-------
7.0    DISCHARGE TO SURFACE WATERS

In this chapter, the potential risks associated with discharge of treated municipal
wastewater into surface-water bodies are evaluated for South Florida.

7.1    Definition of Discharge to Surface Waters

In South Florida, treated wastewater managed by this option is discharged into canals,
creeks, and estuaries. At a minimum, wastewater discharged to surface waters must
receive secondary treatment with basic disinfection. However, wastewater discharged to
some water bodies (for example, Tampa Bay, Indian River Lagoon) must first receive
advanced treatment, including nutrient removal.

Florida's Anti-Degradation Policy, which prohibits surface-water resources from being
degraded, discourages discharge to surface waters because of the high cost of treatment
and the ecological risks, which are generally perceived as high. Even treatment plants
that use this option generally do so infrequently, as a backup when other options (for
example, reuse) are not available.

7.2    Use of Discharge-to-Surface-Waters Option in South Florida

The discharge-to-surface-waters option is used to varying degrees throughout South
Florida. As described in Chapter 2, Figure 2-2, facilities in Brevard, Hillsborough, and
Sarasota counties  make significant use of this option. Facilities in Hillsborough County
rely on this option (roughly 75% of total design capacity) to a greater extent than do
facilities in most other counties in South Florida. In Pinellas and Collier counties,
treatment facilities use a combination of options, including discharge to surface waters. In
Collier County, discharge to surface waters accounts for an insignificant portion (1%) of
the total design capacity. Facilities in Broward, Palm Beach, and Dade counties rely
primarily upon ocean outfalls and underground injection and do not discharge to surface-
water bodies (see  Figure 2-2).

The treatment facilities reviewed in this study that discharge to surface waters either
discharge directly to estuaries with brackish water, coastal embayments, or to freshwater
creeks or canals that eventually discharge to embayments. In Brevard County, the South
Beaches  and Cape Canaveral wastewater treatment facilities discharge to the Indian River
Lagoon only when no other practical alternative exists. The Indian River Lagoon System
and Basin Act of 1990, contained in Chapter 90-262, Laws of Florida, "prohibits new
discharges or increased loadings from domestic wastewater treatment facilities into
surface waters...." (FDEP, 2002a). Exceptions are made if the applicant can meet the
following conditions:

   •   The permit applicant conclusively demonstrates that no other practical alternative
       exists and that the discharge will be treated to advanced treatment levels or higher
                                       7-1

-------
    •   The applicant conclusively demonstrates that the discharge will not cause or
       contribute to water-quality violations and will not hinder efforts to restore water
       quality in the Indian River Lagoon System
    •   The discharge is an intermittent discharge to surface waters occurring during wet
       weather conditions, subject to the requirements of applicable Florida Department
       of Environmental Protection (DEP) rules.

The Act also requires facilities to investigate the feasibility of using reclaimed water to
promote reuse and reduce nutrient loadings. Based on these requirements, the Cape
Canaveral treatment plant was upgraded in the mid-1990s to provide advanced
wastewater treatment (AWT). The new AWT plant is part of a reclaimed water system
that supplements the City of Cocoa Beach's reclaimed water supply. Discharge to the
Banana River, a segment of the Indian River Lagoon, is allowed during periods of wet
weather or when demand for reclaimed water is low (FDEP, 20021; Cape Canaveral
Wastewater Treatment facility, personal communication).

In Hillsborough County, the Howard F. Curren AWT plant serves the city of Tampa. In
2000, the plant managed 48.5 million gallons per day (mgd) using a combination of
discharges to Hillsborough Bay (a portion of Tampa Bay) and reuse of reclaimed water
for cooling and irrigation (City of Tampa, Florida, 2001). In  Sarasota County, the
Gulfgate and Southgate treatment plants discharge into two freshwater creeks, Phillippi
Creek and Methany Creek. These eventually drain to Roberts Bay (Marella, 1999).
Gulfgate has a permit capacity of 1.80 mgd and no reuse capacity. Southgate has a permit
capacity of 1.36 mgd and very limited reuse capacity. Both facilities discharge
approximately 70% to 80% of their permitted capacity, and each is planning for expanded
reuse  (Joseph Squitieri, Florida Southwest DEP, personal communication).

7.3    Environment Into Which Treated Wastewater Is Discharged

7.3.1   Estuarine Environments

An estuary is defined as "a semi-enclosed coastal body of water that is connected to the
sea and within which seawater is measurably diluted  with fresh water from land
drainage" (Pritchard, 1967). Estuaries are some of the most productive, diverse, and
complex ecosystems on earth. They exhibit tremendous temporal and spatial variability in
their physical, chemical, and biological characteristics.

Lagoons are considered a type of estuary. They are produced by wave action and are
typically found behind a barrier beach or spit. Lagoons are characterized as being less
well drained and are uniformly shallow, often less than 2 meters deep. Physical processes
of mixing and  circulation in lagoons are mostly wind-dominated, whereas freshwater
inflow (from surface water and groundwater) tends to drive mixing and circulation in
salt-marsh estuaries.

The Tampa, Sarasota, and Florida bays are representative of estuarine coastal
embayments in South Florida. The Indian River Lagoon is an example of a lagoon
                                       7-2

-------
system. Tampa Bay, Sarasota Bay, and Indian River Lagoon each receive effluent
discharges treated to AWT standards. Although Florida Bay does not receive known or
permitted discharges of treated wastewater, there are a number of relevant concerns
regarding its water quality and aquatic habitat. These concerns establish a useful context
in which to consider risks associated with the discharge-to-surface-waters option.

Potential human health and ecological risks associated with discharges to these
environments would be greatly influenced by site-specific flushing rates and the depths of
water bodies.

7.3.1.1 Tampa Bay

Tampa Bay is located on the west coast of the Florida peninsula and is part of the Gulf of
Mexico. This extremely shallow bay (average depth of 4 meters) is the largest open-water
estuary in Florida, encompassing over 400 square miles and with over 100 freshwater
tributaries (Pribble et al., 1999). Dominant habitats in the Tampa Bay estuary include sea-
grass beds, mangrove forests, salt marshes, and oyster bars. Wildlife is abundant; over
40,000 breeding pairs of birds, such as the brown pelican and roseate spoonbill, nest in
Tampa Bay every year. The bay is also home to dolphins, sea turtles, and manatees.

Tampa Bay was heavily polluted before 1979. This pollution largely resulted from
discharges of primary-treated wastewater from the Hooker's Point Wastewater Treatment
Facility (now the Howard F. Curren Plant) into Hillsborough Bay, a subembayment of
Tampa Bay. Since the state of Florida began requiring advanced treatment to remove
nitrogen, the bay has been recovering. Water clarity and the health of benthic
communities have improved, and sea grasses have reappeared (City of Tampa Bay  Study
Group, 2001a, 2001b). While the adverse effects of discharged wastewater have been
reduced, the bay is still suffering from other pollution sources, particularly atmospheric
and nonpoint source loading of nutrients. Sediment quality in Hillsborough Bay remains
impaired; 33% of sediments are of marginal quality with respect to metals, and 8% of
sediments are of poorer quality (Pribble et al., 1999).

7.3.1.2 Sarasota Bay

Sarasota Bay, located on the Gulf of Mexico in southwest Florida, is another coastal
embayment that receives discharges of treated municipal wastewater. The bay is
composed of two major embayments, Sarasota Bay and Little Sarasota Bay, and many
smaller embayments. The bay is 56 miles long and ranges in width from 300 feet to 4.5
miles. Average depth throughout much of the bay ranges from 8 to 10 feet (Roat and
Alderson, 1990). Sarasota Bay exhibits wildlife and habitat that are very similar to
Tampa Bay, including mangroves, sea grasses, marine mammals, and waterfowl.

Since 1990, nitrogen discharges from wastewater treatment plants have been reduced by
80% because of the implementation of AWT and reuse programs (Sarasota Bay National
Estuary Program, 1993). As a result, water quality and habitat quality have improved.
                                       7-3

-------
Sea-grass coverage in the bay has increased by 18% since 1988 (Sarasota Bay National
Estuary Program, 2000).

7.3.1.3 Indian River Lagoon

The Indian River Lagoon is located on the east coast of Florida, stretching 156 miles
from Ponce de Leon Inlet, south of Daytona Beach, to Jupiter Inlet near West Palm
Beach (Adams et al., 1996). The Indian River Lagoon is a lagoonal estuary composed of
several water bodies, including the Indian River, the Banana River, and Mosquito
Lagoon. The lagoon system receives inputs of salt water via inlets from the ocean. Fresh
water is received in the form  of direct precipitation, groundwater seepage, surface runoff
(discharges from creeks, streams,  and drainage systems), and point sources such as
wastewater treatment plants. The long narrow shape and shallow waters of the lagoon
result in sluggish circulation patterns in many places. Circulation is primarily wind-
driven, and tidal exchange is  limited to six widely separated inlets with restricted tidal
flushing (Adams et al., 1996).

In some areas, habitat loss and alteration have been significant. Portions of the Banana,
North Indian, and South Indian rivers have experienced the greatest long-term declines in
sea-grass cover within the lagoon system (Adams et al., 1996). Approximately 27% of
the mangrove acreage in the Fort Pierce area was lost between 1940 and 1987 (Hoffman
and Haddad, 1998). Many salt marshes and mangrove swamps were impounded and
flooded to control mosquito breeding.

7.3.1.4 Florida Bay

Florida Bay is located at the southernmost tip of Florida, bounded by the mainland and
the Keys. It is a semi-enclosed, shallow, oligotrophic bay, with depths ranging from 6 to
30 feet.  The watershed, which discharges to the bay, includes all of the freshwater
wetlands south of Lake Okeechobee. This vast area slopes gently and drains towards
Florida Bay and the Gulf of Mexico (NOAA, 1999).

Although there are no known discharges to surface waters of municipal wastewater into
Florida Bay, conditions in Florida Bay provide examples of many of the natural resource
issues confronting wastewater and water managers in South Florida. The Florida Bay
hydrologic system has been highly altered, largely through the construction of a complex
canal and levee system to control flooding and provide fresh water for agriculture. The
U.S. Geological Service (USGS) has been investigating environmental changes that have
occurred over the past 150 years within Florida Bay and the surrounding South Florida
ecosystem (McPherson et al., 2000; McPherson and Halley, 1996). Recent studies (Boyer
et al.,  1997, Brewster-Wingard and Ishman, 1999; Brewster-Wingard et al., 1996) have
focused on describing temporal and spatial variability within the bay ecosystem. These
studies show the following:

    •    Salinity in the bay has increased since the 1950s
                                       7-4

-------
    *   Before 1940, fluctuations in salinity and sea-grass distribution matched a natural
        cycle; since 1940, fluctuations have been greater and no longer match a natural
        cycle
    •   Sea grass and macrobenthic algae were much less abundant in the 1800s (and
        early 1900s) and have increased in the last half of the 20th century
    *   Invasive plants (for example, cattails) have increased in number and are slowly
        displacing the native saw grass communities along the canals that form part of
        the drainage system to Florida Bay
    •   Regional ecosystem disturbances occurring in the late 20th century have been
        accelerated by human activities
    •   Between 1991 and 1994, in the central region, nitrate, ammonia, and chlorophyll
        a increased
    •   Over the past 7 years, concentrations of phosphate and total phosphorus
        decreased dramatically throughout the bay
    •   The bay is becoming more phosphorus-limited from west to east.

In recent times, the bay has experienced sea grass die-offs, algal blooms, and declines in
the populations of shellfish and sponges (USGS, 1996a). In western Florida Bay, a
massive sea grass die-off began in 1987. Since then, some recovery of sea grasses has
occurred, while other areas have been slow to revegetate. Algal blooms have been
reported in the last few years across western Florida Bay, extending to the Florida Keys
(NOAA, 1999).

7.3.2   Freshwater Environments

Much of the information that informs this analysis of the discharge-to-surface-waters
option was obtained from treatment facilities located in Brevard, Hillsborough, and
Sarasota counties. These facilities discharge directly to estuaries or to creeks or canals
that discharge to an estuarine environment. This study did not reveal any effluent
discharges to freshwater lakes or ponds in South Florida.

Florida's surface-water features include extensive wetlands and numerous lakes, streams,
and canals. Streams and wetlands in South Florida have direct hydrologic connections to
the surficial aquifer (Randazzo and Jones, 1997). Much of South Florida was originally
covered with wetlands. Canals, which are a prominent surface-water feature in South
Florida, were dug to drain these wetlands and make the land useable. Canals are the
major surface-water drainage feature in South Florida outside of the Everglades
(Englehardt et al., 2001). Many canals that receive effluent discharges subsequently
empty into saltwater bodies.

Canals are generally man-made waterways or artificially improved rivers; they serve
various  uses such as irrigation, shipping, recreation, and flood control (Kapadia and
Swain, 1996). They vary in size from a few feet wide and deep, to several hundred feet
wide and 12 to 15 feet deep. Some canal banks are earthen, while others are encased in
concrete.
                                       7-5

-------
Surface-water quality throughout large areas of South Florida has already been degraded
by human activities, as summarized in two USGS reports on the National Water Quality
Assessment (NAWQA) Program Study of South Florida. The USGS made several major
findings concerning surface-water quality in South Florida (McPherson et al., 2000;
McPherson and Halley, 1996):

   •   Concentrations of total phosphorus at NAWQA sites in South Florida exceeded
       the Environmental Protection Agency's (EPA's) Everglades water-quality
       standard of 0.01 milligram per liter (mg/L) and were above Everglades
       background levels. A major source of the phosphorus is fertilizer from
       agriculture.
   •   Dissolved organic carbon (DOC) concentrations were relatively high when
       compared with those in other waters of the United States. High DOC
       concentrations provide food for microorganisms to grow, reduce light penetration
       in water, and enhance transport and cycling of pesticides and trace elements, such
       as mercury.
   •   Pesticides were detected in almost all South Florida NAWQA samples. Most
       concentrations were below aquatic-life criteria, but the criteria do not address
       cumulative effects of mixtures of pesticides or their degradation products, which
       were common in the samples. Organochlorine pesticides, such as DDT and its
       degradation products, are still prevalent in bottom sediment and fish tissue at
       South Florida NAWQA sites,  even though use of these pesticides has been
       discontinued in recent decades.
   •   Exotic plants and animals pose a threat to native biota, and herbicides that were
       used to control exotic plants were detected in surface water at NAWQA sites.
   •   Of 21 NAWQA areas nationwide, the Everglades has the second highest
       enrichment of methylmercury relative to mercury in sediments; methylmercury is
       highly biologically active and can be taken up by biota.
   •   The frequency of external anomalies (lesions, ulcers, and tumors) on fish
       collected at two NAWQA sites in South Florida places these  sites among the top
       25% of 144 NAWQA sites sampled nationwide. Such anomalies may indicate that
       fish are stressed by contamination.

The NAWQA study found that major causes for degradation of surface-water quality
include modification of drainage patterns, wetland destruction, runoff from agricultural
and urban areas, high concentrations of DOC and its effects on mercury transport and
light transmission, and release of exotic species.

The USGS also collected water-quality samples between 1996 and 1997 within selected
southeast canals that show increases in nutrient concentration corresponding to patterns
of land use. For example, nitrate concentrations were highest in agricultural areas;
ammonia and total and inorganic phosphorus concentrations were highest in urban areas;
total organic nitrogen was highest in wetlands (Lietz, 2000).

In summary, surface-water quality in South Florida shows significant degradation as an
apparent result of urban and agricultural activities. Canals in areas of urban and
                                       7-6

-------
agricultural land use commonly contain water with high concentrations of nutrients,
coliform bacteria, metals, and organic compounds when compared to water taken from
areas that are remote from these canals. Wildlife has been stressed by human alteration of
the hydrologic regime and by the addition of nutrients, sediment, and other pollutants to
surface-water bodies (McPherson et al., 2000; McPherson and Halley, 1996).

7.4    Option-Specific Regulations and Requirements

This section describes regulations concerning treatment and discharge of wastewater to
surface-water environments.

7.4.1   Treatment and Disinfection Requirements

At a minimum, treatment prior to discharge to surface water must include secondary
treatment with basic disinfection (Florida Administrative Code [FAC] 62-600.510(1)).
When discharges to surface waters is used as a backup to reuse systems, wastewater is
frequently treated to reclaimed-water standards before being discharged. Discharge to
Class I drinking waters requires principal treatment, which consists of secondary
treatment and high-level disinfection (see Chapter 2). Discharge to waters contiguous to
Class I waters requires review of the travel time of effluent to the drinking-water intake;
the discharge must also meet Technology Based Effluent Limits (TBEL) or Water
Quality Based Effluent Limits (WBEL), as established by the permit The Florida DEP
may require that a facility meet additional water-quality-based effluent limits; these
provide and enforce more stringent requirements for effluent quality. TBELs and WBELs
are based on the characteristics of the discharge, the receiving-water characteristics, and
the criteria and standards of FAC 62-302.

Effluent discharge must not exceed 10 mg/L total nitrogen (FAC 62-600.420(2)(a)(2)),
and effluent must contain maximum pollutant levels less than those specified for
community water systems in FAC 62-550. These facilities must be designed to reduce
total suspended solids to 5.0 mg/L or less before the application of disinfectant (FAC 62-
600.540(5)(e)).

In order to be permitted to discharge to either Tampa Bay or the Indian River Lagoon,
wastewater treatment plants must treat using AWT. Typically, AWT includes secondary
treatment, basic disinfection, nutrient removal (nitrification, denitrification, and
phosphorus removal), additional removal  of metals and organic compounds, and
filtration. Dechlorination is also required (see Appendix Table 1-1). AWT standards must
be met on an average annual basis. AWT standards are summarized as follows:

   •   Carbonaceous biological oxygen demand (CBODs) must be less than 5 mg/L
   •   Total suspended solids must be less than 5 mg/L
   •   Total nitrogen (as N) must be less  than 3 mg/L
   *   Total phosphorus (as P) must be less than 1 mg/L
   •   Discharge to a treatment or receiving wetland may not exceed 2 mg/L total
       ammonia (as N) on a monthly average.
                                       7-7

-------
Some treatment plants utilize wetland treatment before discharge into surface-water
bodies; this provides further reductions in nutrient concentrations prior to discharge.

Basic disinfection (no more than 200 fecal coliform colonies per 100 milliliters (mL)) is a
minimum requirement for all discharges to surface waters in Florida. High-level
disinfection (fecal coliform removal below detectable limits per 100 mL) is required of
all facilities discharging to Class I surface waters. Intermediate-level disinfection may be
allowed, if discharge is to wetlands with restricted public access (FAC 62-600.440(5)g)
or to surface waters that serve as backup to a reuse system and provided that there is no
discharge to Class I waters or their tributaries (FAC 62-600.440(5)(h)). Dechlorination of
chlorinated wastewater before discharge to surface waters is also required (see Tables 2-4
and 2-5).

Currently, there are no federal or state limits for concentrations of the pathogens Giardia
lamblia or Cryptosporidium in treated wastewater. However, on January 1, 2002, the
EPA did establish drinking-water treatment requirements for these pathogenic
microorganisms. The EPA mandated drinking-water treatment to remove 99.9% of
Giardia lamblia and 99% of Cryptosporidium from raw water sources (National Primary
Drinking Water Standards, CFR 141). Florida DEP applies a numerical standard (no
more than 5.8 cysts or oocysts per 100 L, which corresponds to a 1 in 10"4 human illness
risk) for Cryptosporidium and no more than  1.4 cysts per 100 L for Giardia in reclaimed
water (York et al., 2002). These recommended limits address the significant human
health risks that may be associated with ingestion of viable pathogenic protozoans present
in unfiltered or inadequately filtered treated wastewater.

7.4.2   Standards for Surface-Water Quality

In addition to discharge standards, Florida has use and classification standards for
surface-water bodies (FAC 62-302.530). The standards are meant to protect the
designated use of the water bodies. Table 7-1 summarizes the uses and criteria for some
of the relevant stressors reviewed in this study (FAC 62-302.530).
                                       7-J

-------
Table 7-1.    Criteria for Surface-Water Quality Classifications
Parameter
Fecal
coliform
bacteria
* Copper
Nitrate
Nutrients
Phosphorus
Units
Numbers
per 100
mL
Hg/L
mg/L

ug/L
Class I: Potable-
Water Supply
MPN or MF counts
cannot exceed
monthly average of
200, nor exceed
400 in 10% of
samples, nor
exceed 800 on any
day. Monthly
averages must be
based on minimum
of 5 samples taken
over a 30-day
period.
Cu(e(0.8545[lnH3-
1.465)
10, or
concentration that
exceeds nutrient
criteria.
Class II:
Shellfish
Propagation
or
Harvesting
MPN shall
not exceed a
median value
of 14, with
not more than
10% of the
samples
exceeding 43,
nor exceed
800 on any
day.
2.9

Class III: Recreation, Propagation,
and Maintenance of a Healthy Well-
Balanced Population of Fish and
Wildlife
Fresh
MPNorMF
cannot exceed
monthly average of
200, nor exceed
400 in 10% of
samples, nor
exceed 800 on any
day. Monthly
averages must be
based on minimum
of 5 samples taken
over a 30-day
period
Cu(e(0.8545[InH]-
1.465)

Marine
MPNorMF
counts shall not
exceed monthly
average of 200, nor
exceed 400 in 10%
of samples, nor
exceed 800 on any
day. Monthly
averages must be
based on minimum
of 5 samples taken
over a 30-day
period
0.9

Discharge of nutrients is limited as needed to prevent violations of other
standards. Man-induced nutrient enrichment (total nitrogen or total phosphorus)
is considered degradation (Section 62-302.300, 62-302.700, and 62-4.242 FAC).
Nutrient concentrations in a body of water cannot be altered so as to cause an
imbalance in natural populations of aquatic flora and fauna.

0.1

0.1
*Florida surface-water quality standards for metals were used as assessment endpoints. The standard for copper in
Class I and Class in freshwater bodies takes into account water hardness (CaCO3) and provides a range from 0.00361
mg/L to 0.036 mg/L (corresponding to a range in CaCO3 from 25 to 400 mg/L).
MPN = most probable number
MF = membrane filter
In addition to the above classes of water bodies, Florida has a category for Outstanding
Florida Waters and Outstanding National Resource Waters. This generally refers to
waters of exceptional recreational or ecological significance that are found within
national and state parks and wildlife preserves. A complete listing is available under 62-
302 and includes the waters of the Everglades National Park. These waters fall under
Florida's Antidegradation Policy and are afforded the highest protection.

In December 2000, the EPA published recommendations for ambient freshwater quality
criteria for different regions around the country. These water-quality goals or
recommendations are intended to assist states and tribes in establishing nutrient limits for
water bodies that are consistent with Section 303(c) of the Clean Water Act. These
criteria are recommended, not required.
                                          7-9

-------
Using historical data and reference sites, the EPA determined that the unimpacted lakes
and reservoirs of South Florida (Ecoregion XIII) had a mean background predevelopment
total nitrogen concentration of 1.27 mg/L (US EPA, 2000a). The 3 mg/L standard for
treating nitrogen before discharge represents a concentration that is 2.4 times higher than
this background.

Similar mean background predevelopment nitrogen concentrations for rivers and streams
in South Florida are not currently available. In Ecoregion XII, which includes central and
northern Florida (as well as portions of Alabama, Georgia, and Mississippi), the EPA
recommends a background total nitrogen concentration of 0.9 mg/L in streams and rivers
(US EPA, 2000b). The 3 mg/L standard for treatment before discharge represents a
concentration that is approximately 3.3 times higher than this background level.

Total phosphorus  includes all forms of phosphorus, both inorganic and organic. For
streams and rivers in nearby Ecoregion XII, the EPA recommends a total background
phosphorus water-quality criterion of 40.0 ug/L, or 0.040 mg/L (US EPA, 2000b). This is
two orders of magnitude lower than the AWT treatment standard. Florida regulations
require that plants that discharge to surface-water bodies treat wastewater so that the final
concentration of total phosphorus in the discharged effluent is 1 mg/L. The EPA has
determined that the unimpacted lakes and reservoirs of South Florida (Ecoregion XIII)
had a mean background predevelopment total phosphorus concentration of 17.50 ug/L, or
0.0175 mg/L (US  EPA, 2000a). The standard for AWT-treated wastewater, 1 mg/L,
represents a concentration 57 times larger than this recommended background level for
lakes and reservoirs/

7.5    Problem Formulation

Human health and ecological risks that may be associated with the discharge-to-surface-
waters option are  expected to be highly site-specific.  There may be substantial
differences of scale in important physical processes and variations in the assimilative
capacity of individual  water bodies. Therefore, this option-specific risk analysis focuses
on whether surface-water quality standards are likely to be exceeded by actual
discharges. This is coupled with a review of the types of adverse effects that might be
anticipated where  surface-water quality standards are exceeded. Implicit in this approach
is an assumption that surface-water quality standards are adequately protective of human
and ecological health.  For one area where this assumption may be suspect (standards for
nutrient discharges), a set of surface-water quality recommendations serve to expand this
analysis to include additional considerations.

7.5.1   Potential Stressors

Potential stressors entrained or dissolved in treated wastewater are discharged to surface-
water outfalls located in canals, creeks, or estuaries. Wastewater constituents that may act
as stressors to human or ecological health include nutrients (nitrogen and phosphorus),
certain metals, organic compounds, pathogenic microorganisms, and hormonally active
agents. A group of potential "secondary stressors" (for example, shifts in community
                                       7-10

-------
 structure and productivity) may at the same time be caused by the presence of wastewater
 constituents and, in turn, be the cause for additional adverse effects. Secondary stressors
 include such things as changes to plant, invertebrate, and fish community structure;
 growth of invasive species; reduction in oxygen levels; and harmful algal bloom.

 7.5.1.1 Nutrient Stressors

 Because most, if not all, of the permitted discharges to surface waters eventually reach
 coastal embayments, the risk assessment of these discharges resembles the risk
 assessment of the ocean outfall option in many ways. Nutrient stressors are an example.
 Nutrients  act as ecological stressors when present in surface waters at sufficient
 concentration to overstimulate primary production (leading to eutrophic conditions) or
 otherwise cause adverse changes in ecosystem health or structure (for example, loss of
 native species, growth of invasive species).

 Nitrogen limitation in coastal and ocean waters was reviewed in Chapter 6 (see Paerl,
 1997; Dugdale, 1967; Ryther and Dunstan, 1971; Codispoti, 1989; Eppley, et. al., 1979).
 Freshwater ecosystems are typically characterized by phosphorus limitation (Schindler,
 1977, 1978; Smith, 1982). Phosphorus limitation is generally stems from low levels of
 naturally occurring dissolved inorganic phosphorus. However, ecosystem responses to
 additions of phosphorus will depend on both the levels of additional phosphorus made
 available and the levels of nitrogen that are latent in the ecosystem, often as a result of
 human activity (such as agricultural inputs). In Florida, natural ambient levels of
 phosphorus may be higher than in other areas of the country because of high phosphorus
 content in the regional geology (Valette-Silver et. al., 1999).

 The National Research Council concluded that, while nitrogen is important in controlling
 primary production in coastal waters and phosphorus is important in freshwater systems,
 both need to be managed to avoid overproduction (National Research Council, 2000).
 The causes of eutrophication in fresh and marine ecosystems are not identical but do
 reflect ecological and biogeochemical processes. In either case,  the relative inputs of
 nitrogen and phosphorus and the extent to which nitrogen fixation can alleviate limitation
 play a crucial role in determining the limiting nutrient to production in aquatic
 ecosystems. The limiting nutrient is the nutrient in shortest supply in a natural system. In
 marine waters, nitrogen is generally present in low concentrations, while in fresh water,
 phosphorus is present in low concentrations.

 While phosphorus limitation in fresh water seems universal, there are exceptions to the
 general principle that nitrogen is limiting in coastal ecosystems. For example, the
Apalachicola estuarine system on the Gulf coast of Florida appears to be phosphorus-
 limited (Myers and Iverson, 1981). Howarth (1988) and Billen et al. (1991) suggest that
this is related to the relatively high ratio of nitrogen to phosphorus inputs. Howarth et al.
 (1995) suggests that there is a tendency for estuaries to become  more nitrogen-limited as
they become more affected by humans and as nutrient inputs increase overall.
                                       7-11

-------
In nearshore tropical marine systems, phosphorus tends to be more limiting for primary
production (Howarth et al., 1995). In some major estuaries, nutrient limitation switches
seasonally between nitrogen and phosphorus. Examples of such seasonally varying
nutrient limitation include the Chesapeake Bay (Malone et al., 1996) and portions of the
Gulf of Mexico, including the so-called "dead zone" (Rabalais et al., 1999). Tampa Bay
has become a nitrogen-limited system instead of a phosphorus-limited system because of
the long-term mining of phosphorus. In contrast, Florida Bay is phosphorus-limited
(Bianchi et al., 1999).

7.5.1.2 Metals

Trace metals in wastewater are potential stressors because they may cause adverse human
health and ecological effects at high concentrations. Trace metals are frequently elevated
in wastewater as a result of common industrial usage. Levels in treated wastewater are, in
general, greatly reduced, but trace metals are still frequently used as tracers of wastewater
in the aquatic environment (Matthai and Birch, 2000; Flegal et al.,  1995; Hershelman  et
al., 1981; Ravizza and Bothner, 1996; Morel et al., 1975). Additional sources of metals
that may contribute to levels present in surface-water bodies include combustion of fossil
fuels, mining activities, stormwater runoff, atmospheric deposition, and other surface-
water and groundwater sources (Burnett et al., 1980; Finney and Huh, 1989; Forstner  and
Wittman,  1979; Huh et al., 1992; Huntzicker et al., 1975; Klein and Goldberg, 1970).

Metals can bioaccumulate in the food chain, thus having adverse secondary impacts on an
ecosystem. For example, arsenic may bioaccumulate in aquatic organisms. However,
there is considerable variability in aquatic food-web bioaccumulation (Penrose et al.,
1977; Woolson, 1977). See Chapter 3, Methodology, for further description of metals as
a potential stressor in the environment.

7.5.1.3 Organic Compounds

Potential organic stressors that may be present in treated wastewater include volatile
organic compounds (VOCs), synthetic organic compounds (such as pesticides,
herbicides, surfactants), trihalomethanes, and some hormonally active agents (endocrine
disruptors). See Chapter 3, Methodology, for a further description of organic compounds
as potential stressors in the environment.

Hormonally active  agents may have potentially adverse effects on aquatic organisms,
based on the scientific literature. A study conducted in the United Kingdom found that
wastewater induced vitellogenin synthesis in caged and wild fish several kilometers
downstream of points of discharge (Rodgers-Gray et al., 2000); vitellogenin is a protein
important  to yolk production. These effects were induced at dilutions of treated
wastewater ranging from 9.4% to  37.9%. Similar studies were conducted in the United
States. However, there was no apparent vitellogenin induction in fathead minnow
(Pimephales promelas} in response to exposure to treated wastewater (Nichols et al.,
1998).
                                      7-12

-------
 Studies in Florida have documented potential adverse effects from exposure to
 hormonally active agents in upland and freshwater organisms, including the Florida
 panther (Facemire, et al., 1995) and American alligator (Guillette, 1994, Semenza, 1997).
 However, these studies do not document the sources of these agents.

 These studies indicate that hormonally active agents may be capable of causing
 potentially adverse health effects in aquatic organisms.  However, more information is
 needed to determine how these compounds cause adverse reactions.

 7.5.1.4 Pathogenic Microorganisms

 Pathogenic stressors that may be present in treated wastewater include enteric bacteria,
 protozoans, and viruses associated with human or animal wastes. Secondary treatment,
 chlorination, and filtration generally remove all viruses, helminthes, and pathogenic
 bacteria. However, the protozoans Giardia and Cryptosporidium form cysts that are
 resistant to chlorination and that can only be removed through careful filtration. The
 Florida DEP has evaluated monitoring data from reclaimed-water treatment facilities that
 treat wastewater intended for reuse or discharge to surface waters. Wastewater treated at
 some facilities still contains levels of Cryptosporidium and Giardia that may pose human
 health risks, despite chlorination and filtration (York et  al., 2002).

 Much of the information concerning survival and transport of pathogenic protozoans
 discussed in Chapter 4 applies to discharges to surface waters. Cryptosporidium oocysts,
 for example, have a T9o (that is, the time needed to inactivate 90% of the population) of
 approximately 200 days (Robertson et al.,  1992). This time frame is long enough that
 discharged effluent traveling over short distances and short travel times may still contain
 some pathogenic protozoans.

 Contamination of Florida's coastal environments with enteric viruses, bacteria, or
protozoans is a widespread and chronic problem. This is notably the case for Tampa Bay,
 Sarasota Bay, and the marine environment surrounding  the Florida Keys. There are a
number of potential causes for this. They include the prevalence and high density of
onsite sewage-disposal systems (such as septic systems), the presence of predominantly
porous and sandy soils, and karst topography and the hydrologic connection between
groundwater and coastal embayments and estuaries (Lipp et al., 2001; Paul et al.,  1995).

7.5.1.5 Secondary Stressors

 Secondary stressors are the result of exposure to the potential stressors discussed above
and include the following:

   •  Increased primary productivity
   •  Increased oxygen demand and hypoxia
   •  Shifts in community structure caused by anoxia and hypoxia
   •  Changes in phytoplankton community structure
   •  Harmful algal blooms
                                      7-13

-------
    •   Marine mammals and human impacts from harmful algal blooms
    •   Degradation of sea-grass and algal beds and formation of nuisance algal mats
    •   Coral reef destruction
    •   Trophic impacts.

Sea-grass degradation in Tampa Bay, Sarasota Bay, and Indian River Lagoon has been
attributed to nutrient loading, from both point and nonpoint sources.  Sea grass serves as a
valuable habit for juvenile fish, some marine mammals, and shellfish as it provides food,
oxygen, and refuge. In addition, sea grass stabilizes the bottom substrate, keeping
sediment out of the water column. The loss of sea grass can also cause secondary effects
by adversely affecting other species that utilize this habitat. Nutrient  loading that
increases phytoplankton populations can damage sea grass; this in turn decreases light
transmission to the substrate.

The increase in production can also result in increased organic loading that, upon
decomposition, utilizes oxygen, thus creating hypoxic or anoxic conditions. These
conditions can result in fish kills or a decrease in available fish habitat.

Changes in nutrient concentrations in the water column can alter the  phytoplankton
community structure. This may result in increased nuisance or harmful algal blooms. In
addition, the availability of silica and iron appears to play a role in coastal eutrophication
and may promote the formation of harmful algal blooms (National Research Council,
2000).

Harmful algal blooms (HABs) pose particular concerns in brackish, coastal, and estuarine
environments. Harmful algal blooms taxa and associated problems in coastal or estuarine
environments are described in the Chapter 6. The causes of harmful algal blooms are still
controversial. They  include a variety of physical, chemical and biological changes, such
as climate change, increased pollution and nutrient inputs, habitat degradation through
dredging, resource harvesting and regulation of water flows, failure of grazers to control
algal growth, and better monitoring. It is uncertain whether higher numbers of harmful
algal bloom reports  in recent years are a result of an actual increase in harmful algal
blooms or better water-quality monitoring.

Harmful cyanobacterial ("blue-green") algal blooms can occur in warm  stratified areas in
embayments and estuaries, where nitrogen concentrations are low, salinities are reduced,
and phosphorus is enriched through upwelling, eddies, or mixing. Phosphorus limitation
is generally more important than nitrogen limitation (Sellner, 1997).  In Florida, extensive
blooms of the cyanobacterium Lyngbya majuscula were documented in Tampa Bay in
1999 and from Sarasota Bay to Tampa Bay in 2000. Although this species is not toxic, it
is a nuisance alga because it produces large, slimy, brown odorous floating mats (Florida
Fish and Wildlife Conservation Commission, 1999). The causes for this bloom are
unknown; it is not believed that discharges of treated effluent played  a significant role.

Harmful algal blooms ofGymnodinium breve occur frequently off the southwest coast of
Florida, especially from Clearwater to Sanibel  Island, occurring in 21 of the last 22 years
                                      7-14

-------
 (Boesch, et al., 1997). Blooms move inshore and can have impacts on the health of
 humans or wildlife. In 1996, more than 150 manatees died from exposure to brevetoxin
 during prolonged red tides along the southwest coast of Florida (Steidinger et al., 1996).
 There is some evidence that dense blooms of Gymnodinium rely on new nutrient inputs;
 human impacts to watersheds may be responsible for extending the duration and adverse
 effects of red tides once they enter nearshore areas (Boesch et al.,  1997).

 Effects of secondary stressors also include changes in trophic processing of organic
 matter, uptake and bioaccumulation, biodiversity and populations, and growth of invasive
 species displacing native species.

 7.5.2  Potential Receptors and Assessment Endpoints

 Assessment endpoints represent discrete natural resource values or functions deemed
 important to local ecology or natural communities. Water-quality standards are set based
 upon such endpoints. For example, maintenance and protection of aquatic life might be
 one such endpoint. Other endpoints might be fishable and swimmable waters. Water-
 quality criteria then would be set, based on reaching that goal. As discussed in section
 7.4.2, Florida uses a class system to designate uses of water bodies and applies water-
 quality standards to meet those uses.

 The water-quality standards are set based upon the best science available and are
 conservative. Still, there are many unknowns and uncertainties, particularly when setting
 standards related to protecting complex ecosystems. For example,  many times numerical
 standards are not set for nutrients in water bodies because the ecoystem effects are very
 site-specific.

 Canals, which are a frequent receptor for discharge of treated wastewater into surface-
 water bodies, are often hydrologicly connected to groundwater and are recharged by
 groundwater. Adams (1991) examined water in the surficial aquifer and canals in Martin
 and Northern Palm Beach counties and concluded that groundwater quality did not seem
 to be  affected by canal water, probably because the aquifer is discharging to the canal
 rather than the canal recharging the aquifer. However, water  from canals may enter the
 surficial aquifer when canals are used as an irrigation source. Drinking-water receptors
 (underground sources of drinking water (USDWs) or water-supply wells) may be
 exposed where surface waters have a direct hydrologic connection to the groundwater
 resource

 7.5.3   Potential Exposure Pathways

 When human health or ecological receptors are exposed to wastewater constituents in
 sufficient concentration, these receptors may be at risk for potentially adverse health
 effects. Complex processes and interactions govern how wastewater discharged to
 surface waters will move and behave. These processes and interactions define the
pathways that may expose receptors to stressors present in treated wastewater.
                                       7-15

-------
Potential transport processes include advective transport in stream and nearshore
currents, and estuarine and tidally driven circulation. The action of these transport
processes varies substantially over time and space. Patterns and mechanisms of transport
are often quite different in water bodies of different sizes, shapes, and orientations.
Transport processes can also vary substantially within water bodies, over the course of
time, and in response to localized changes in depth, currents, temperature* and many
other factors.

The capacity of water bodies to dilute or assimilate wastewater constituents is
fundamentally important to the fate of potential stressors in surface-water ecosystems and
to the risks that may be posed by such stressors. In this respect, the rate of flow through a
canal or creek and the rate of flushing for an embayment or lagoon are key parameters
that influence both fate and risk. In general, adverse effects are expected to be  greater in
smaller surface-water bodies that flush slowly than in larger water bodies that are well
flushed.

Sedimentation and flocculation are important physical and chemical processes that can
act to take wastewater constituents out of the water column. Turbulent mixing  and
resuspension frequently act to counteract these processes, setting up a dynamic
equilibrium in which materials  are exchanged  (over time and space) between the water
column and sediment  layer. Where conditions are conducive to sedimentation or
flocculation, the sediment layer can become a  sink, potentially affecting local flora and
fauna at the sediment interface.

Potential exposure pathways for ecological receptors include direct ingestion of water or
sediments,  dermal contact and other forms of uptake (for example, diffusion into
submerged plants and soft-bodied invertebrates), and bioaccumulation or food-chain
bioconcentration.  Ecological receptors are exposed to secondary stressors, such as the
disappearance of favorite prey items or reduced levels of available oxygen, through their
trophic relationships and position within the larger biological community.

Potential human exposure pathways include direct ingestion or dermal contact with
surface water and ingestion of contaminated fish, shellfish, or other plants and animals
exposed to  treated wastewater. Drinking-water receptors may be exposed where surface
waters have a direct hydrologic connection to the groundwater resource.

7.5.4  Conceptual Model of Potential Risk for the Discharge-to-Surface
       Waters Option

Figure 7-1 presents a generic conceptual model for the discharge-to-surface-waters
wastewater management option. The primary source of potential stressors is defined as
the wastewater treatment plant from which treated  effluent is routed to one or more
surface-water outfalls. The rate of discharge may vary, depending on the size and
operational status of the facility, but is generally measured in millions of gallons per day.
                                       7-16

-------
Treated wastewater is discharged directly to surface-water bodies. These are
predominantly small, flowing, fresh-to-brackish bodies of water (canals, creeks, and
estuaries). According to the Florida DEP, discharge to closed bodies (ponds and lakes) is
no longer practiced in South Florida. Wastewater is typically treated to a higher level
than effluent discharged through ocean outfalls. Treatment includes secondary treatment
and basic disinfection, followed by filtration and, in some cases, nutrient reduction and
dechlorination to remove harmful chlorination by-products. In the model, nutrient
limitation varies, depending on whether disposal into freshwater, estuarine, or coastal
marine waters is conducted.

Potential ecological receptors include the wildlife, waterfowl, fish, and invertebrates that
are dependent on canals, estuaries, and other surface-water ecosystems for food and
habitat.

Potential human receptors include recreational fishermen, swimmers, agricultural
workers, and others whose work or recreation brings them into close proximity or contact
with surface-water bodies that receive effluent discharges. Waters classified as fishable
and swimmable are assessment endpoints meant to protect these ecological receptors.

Drinking-water receptors may be exposed to wastewater when surface waters have direct
hydrologic connection to the groundwater resource. While this study did not find any
evidence of wastewater discharging to surface waters in direct connection to groundwater
wells in South Florida, it is a consideration when analyzing potential receptors.
7.6    Risk Analysis of the Discharge-to-Surface-Waters Option

In this section, data are integrated into the conceptual model for the discharge-to-surface-
waters option. Actual data on stressors, receptors, and exposure pathways are used to
examine potential risks.

Discharge monitoring data from several public treatment facilities, as well as a database
provided by the Florida DEP (2002b), were used to examine where (and to what extent)
the discharge-to-surface-waters option is used in South Florida. Staff from Florida DEP
assisted in determining which options are utilized by specific treatment facilities
(personal communication, Kathryn Muldoon, February, 2002).

Information to describe the volume and quality of treated wastewater discharged to
surface waters was limited. In order to characterize potential stressors and stressor
concentrations, data were obtained from three AWT plants that discharge to surface
waters (the City of Cape Canaveral and South Beaches treatment facilities  in Brevard
County and the Howard F. Curren treatment plant in Hillsborough County). In addition,
information on AWT effluent managed at two wastewater treatment plants in Sarasota
County (Gulfgate and Southgate Wastewater Treatment Plants) was obtained from the
report by Englehardt et al. (2001) (Appendix Table 1-1). No data were available to
characterize discharges to surface waters treated to less-than-AWT standards.
                                       7-17

-------
                     Activity / Sources
                        of Stressors
System Stressors
                    Wastewater Treatment
                             Plant
oo
                                                       Inorganic
                                                       Constituents
                                                      Volatile Organic
                                                      Constituents
                                                     Synthetic Organic
                                                     Constituents
                                                      Microbiological
                                                      Constituents
                                                      Miscellaneous
                                                      Consfituents
Pathways / Processes
                           Biological Processes

                             Pathogen Mortality
                             Bioaccumulation
                             Biodegradation
                             Biochemical Transformation
                             Respiration
                             Photosynthesis
                           Chemical Processes

                             Sorption / Desorption
                             Redox
                             Precipitation/ Dissolution
                             Photodegradation
                             Chemical Transformation
                             Complex Formation
                           Physical Processes
                             Advection / Diffusion
                             Dilution
                             Buoyancy
                             Sedimentation/ Coagulation
                             Sediment  resuspension
                             Currents
                             Light Scatter /Absorption
                             Volatilization to Atmosphere
                            , Recharge to Surficial Aquifers
                                  Potential Receptors
                                 Phytoplankton and Zooplankton
                                 Submerged Aquatic Vegetation (SAV)
                                 Macroinvertebrates
                                 Fish
                                 Aquatic and Terrestrial Birds
                                 Aquatic and Terrestrial Mammafs
                                 Reptiles arid Amphibians
                                 Endangered Species
                                 Humans
                                  Potential Effects
                                  Eutrophication (excess nutrients and algal
                                     growth, low oxygen)
                                  Harmful Algal Blooms (HABs)
                                  Changes in Phytoplankton and Zooplankton
                                     Communities
                                  Toxic Effects on Aquatic and Terrestrial
                                     Species
                                  Developmental or Reproductive Changes in
                                     Aquatic or Terrestrial Organisms
                                  Reduced Growth of SAV due to Reduction
                                     in Water Clarity
                                  Illness Caused by Micronial Pathogens
                                  Food Web Effects
                                                                                                            Reference: Disposal of Industrial and Domestic Wastes:
                                                                                                            Land and Sea Alternatives, National Academy
                                                                                                            of Sciences, 1984.
                  Figure 7-1.  Conceptual Model of Potential Risks for the Surface Water Option

-------
To describe the proximity and vulnerability of receptors, information was obtained
regarding biological communities present in the receiving water bodies, particularly
sensitive or vulnerable populations. A review of the scientific literature provided
information about potential exposure pathways, adverse impacts, and risks. Wherever
available, previous studies and investigations were used to appropriately expand the
scope of this analysis.

7,6.1  Evaluation of Stressors and Assessment Endpoints

7.6.1.1 Nutrients

Annual average concentrations of total nitrogen in treated wastewater for 1999 and 2001
were calculated from monthly monitoring report averages for the City of Cape
Canaveral's AWT wastewater treatment plant (Appendix Table 1-1). The annual average
concentration of total nitrogen during this period ranged from 0.752 to 0.970 mg/L; the
maximum monthly average was  1.353 mg/L, and the minimum monthly average was
0,321 mg/L of total nitrogen. These values are well below the 3 mg/L AWT standard for
treatment. Background concentrations of nitrate (a component of total nitrogen) at two
ocean locations off the east coast of Florida reported in Hazen and Sawyer (1994) were
0,11 mg/L and 0.16 mg/L. One monitoring result for nitrate for the City of Cape
Canaveral's wastewater treatment plant revealed a nitrate concentration in treated effluent
of 0.062 mg/L. This is an order of magnitude lower than background concentrations of
nitrate reported for the SEFLOE studies in an open ocean environment (summarized in
Hazen and Sawyer, 1994).

Annual average concentrations of total phosphorus for 1999 and 2001 were calculated
from monthly monitoring report  averages for the City of Cape Canaveral's AWT
wastewater treatment plant (Appendix Table 1-1). The annual average concentration of
total phosphorus during this period ranged from 0.119 to 0.152 mg/L; the maximum
monthly average was 0.273 mg/L, and the minimum monthly average was 0.064 mg/L
total phosphorus. The annual average concentrations of total phosphorus are higher than
recommended background levels for total phosphorus in fresh water. Thus, the excess
phosphorus may pose some ecological risks.

Permitted concentrations of nitrogen and phosphorus (3 and 1 mg/L, respectively) in
AWT-treated effluent discharged to surface waters are often greater than background
concentrations in unimpacted water bodies. Phosphorus concentrations in AWT effluent
were generally significantly higher than recommended background concentrations for
fresh waters. However, as indicated above, actual nitrate concentrations in AWT effluent
can be lower than background oceanic nitrate concentrations.

Long-term water-quality and biological monitoring in Hillsborough Bay indicates that
water quality and clarity have improved and shoal grass (Halodule wrightii} has
recovered since AWT was implemented at the Howard F. Curren Wastewater Treatment
Plant (City of Tampa Bay Study  Group, 200 Ib).
                                      7-19

-------
Given the limited use of this disposal option and limited data on actual discharged
effluent, it is difficult to estimate risk for this option except in these more general terms
relating to water-quality standards. Nevertheless, nutrient loading is one of the top
reasons for impairment of surface-water bodies in Florida. It is likely that point sources
are part of this larger problem. Rivers, streams, and canals typically empty into other
water bodies that can be impacted by nutrient enrichment. In some instances, treatment
plants discharge to a wetland before ultimately discharging to surface waters; when this
occurs, the nutrient load decreases and thus the risk from this type of disposal may be
diminished.

7.6.1.2 Metals

Concentrations of all inorganic and secondary analysis metals in AWT effluent reviewed
for this study were below standards for drinking water quality (Appendix Table 1-1).
Copper concentrations in AWT effluent were similar to concentrations found in
secondary-treated effluent (Englehardt et al., 2001). Total copper in advanced treated
wastewater was 0.003 mg/L. This is below copper water-quality standards in Florida.
Because the concentrations of copper in wastewater effluent reported by utilities in this
study were below water-quality standards, it is unlikely that this constituent poses
significant risks to human or ecological health. For the Cape Canaveral plant, copper
concentrations were below detection limits (<0.0005 mg/L).

7.6.1.3 Organic Compounds

Concentrations of trihalomethanes, synthetic organics, and volatile organics were below
drinking-water  standards (Appendix Table 1-1). Compared to the Florida standards for
surface water quality, all trihalomethanes in AWT wastewater were below Class II and
Class III standards for fresh and marine surface-water quality. Class I standards, which
apply to surface waters used as drinking-water supplies, were not met by the AWT
effluent monitoring results reviewed for this study. However, none of the AWT plants
surveyed in this report discharge treated effluent to Class I surface-water drinking
supplies.

All synthetic and VOCs that were analyzed from one monitoring sample of treated
effluent by the City of Cape Canaveral wastewater treatment facility were below
detection limits (Appendix Table 1-1).

The representative contaminant chosen to evaluate potential risk include a number of
estrogenic and estrogen-like substances. Estrogen equivalence is a measure of the
response of breast cancer cells to exposure to strongly estrogenic substances, such as
hormone replacement and birth-control pills (Frederic Bloettscher, personal
communication). Estrogen equivalence was measured from two grab  samples at the
Gulfgate and Southgate treatment plants in Sarasota, Florida. Both of these plants treat to
AWT levels and discharge to surface-water creeks. The average concentration of
estrogen-equivalence substances in the treated wastewater effluent was 3.253 nanograms
per liter (ng/L) (Frederic Bloettscher, personal communication).
                                       7-20

-------
At this point, this information only indicates that these substances may be present in
treated wastewater intended for disposal into surface water. Recent literature suggests
that concentrations below 1 ng/L can cause vitellogenin levels to increase in aquatic
organisms (Sadik and Witt, 1999; Larsson, et al., 1999). The literature suggests that more
study is needed concerning the concentrations at which endocrine disruption may occur
from biodegradation byproducts.

No information is available concerning concentrations of estrogen-like compounds in
ambient surface waters near the outfall sites, nor in ecological receptors at or near the
outfall sites. Ongoing and future research should provide a better framework for
discussing these compounds and evaluating their risks.

7.6.1.4 Pathogenic Microorganisms

Monitoring data reported by the city of Cape Canaveral to the Florida DEP for its
National Pollutant Discharge Elimination System permit indicate that, between 1999  and
2001, the maximum concentration of fecal coliforms in treated effluent (measured
monthly) ranged from 0 to 8 colonies per 100 mL (Cape Canaveral NPDES Database,
1999-2001). As noted above, a certain number of fecal coliforms are permitted, up to a
limit of 200 fecal coliforms per 100 mL of effluent, for all but Class I surface waters.
These concentrations do not meet drinking-water standards.

The Howard F.  Curren Wastewater Treatment Plant in Tampa Bay reported annual
sampling results in 2000  and 2001 for Giardia lamblia and Cryptosporidium^ pathogenic
protozoans that  can cause gastrointestinal illness in humans when ingested (David York,
pers. comm.). In 2000, the concentration of Giardia lamblia and Cryptosporidium were
each less than 0.7 cysts per 100 L of effluent. In 2001, the concentration of Giardia
lamblia was less than 0.29 cysts per 100 L of effluent, and the concentration of
Cryptosporidium was 2.33 oocysts per 100 L of effluent. These numbers are below the
DEP's recommended limit of 5.8 per 100 L for both Cryptosporidium and Giardia.
Monitoring of other wastewater treatment facilities in Florida indicates that a few
facilities do not  meet the informal standard of 5.8 per 100 L, despite the fact that the
effluent is filtered (York  et al., 2002).

7.6.2   Evaluation of Receptors and Exposure Pathways

Some potential ecological receptors in water bodies in Florida that receive treated
wastewater are described below.  Water-quality problems that have arisen or been
corrected through the implementation of improved wastewater treatment are noted.

   •   Submerged aquatic vegetation (such as sea grasses) populations are abundant in
       the nearshore areas surrounding South Florida. In recent years, there have been
       documented changes in the abundance of sea grass in the nearshore environment.
      For example, in Tampa Bay, there have been recent declines in sea-grass
      populations, but this has occurred after several years of sea-grass expansion
      throughout the bay. In the late 1980s and early 1990s, sea grasses were returning
      at the rate of 500 acres a year as Tampa Bay responded to improvements in water
                                      7-21

-------
   quality resulting from improvements in wastewater treatment. The sea-grass
   expansion rate slowed to about 350 acres in the mid-1990s. The latest figures
   show an overall cumulative loss of sea grass to pre-1990 levels (Coastlines, Issue
   11.4).

•  Bordering habitats (such as mangroves and salt marshes) are located throughout
   the nearshore estuarine environment in South Florida. Like sea-grass habitats,
   these areas offer food and refuge to many aquatic species and are affected by
   increased nutrients.

•  The Indian River Lagoon supports one of the most diverse bird populations in
   the United States, with 125 breeding species and 172 species that over-winter in
   the area (Adams et al., 1996). Many bird species in the region are impacted by
   human activities, especially activities that contribute to habitat loss and
   fragmentation. In 1987, the dusky seaside sparrow became extinct in the Indian
   River Lagoon because of alterations to coastal marsh habitat (marsh
   impoundment). Avian communities are also susceptible to overexploitation
   (primarily hunting) and to the adverse effects of widespread use of chemicals
   (especially DDT).
•  Marine mammals, such as the West Indian manatee and the Atlantic bottlenose
   dolphin, inhabit lagoons and estuaries along the Florida coast. One-third of the
   endangered Floridian population of West Indian manatee (Trichechus manatus)
   resides in the Indian River lagoon. Collisions with boats pose the most significant
   threat to these populations, at least from human activities. However,
   Cryptosporidium and Microsporidium  infections have been implicated in recent
   manatee deaths along the Gulf Coast of Florida, according to biologists at
   Tampa's Lowry Park Zoo (Grossfield,  2002). Dolphin (Tursiops truncatus)
   populations are believed to be stable. Approximately 20 dolphin fatalities are
   reported annually; 8% to 12% of these  fatalities are believed to be related to boat
   accidents or fishnet entanglement. A fungal skin disease that affects
   approximately 12% of the dolphin population may be linked to water quality, as
   documented by the Treasure Coastal Dolphin Project conducted in 1994 (Adams
   etal., 1996).

•  Both  green and loggerhead turtles are on the U.S. Fish and Wildlife Service list
   of threatened and endangered species (Adams et al., 1996; Gilmore, 1995;
   Gilmore et al., 1981). The green turtle (Chelonia mydas mydas), a state and
   federally endangered species, inhabits the Indian River Lagoon. Boat collisions
   and fishing line entanglement are believed to be the principal causes of sea turtle
   mortality. However, 40% to 60% of green turtles surveyed in the Indian River
   Lagoon were found to be infected with fibropapillomatosis; this disease may be
   linked to water quality (Ehrhart and Redfoot, 1995).

•  As  of January 1994, 782 fish species were documented in the east-central Florida
   region. At least half of these species use estuaries and lagoons, such as the Indian
                                   7-22

-------
       River Lagoon, at some point in their life histories (Gilmore, 1995; Gilmore et al.,
       1981).

 Toxicity testing results from the city of Cape Canaveral AWT Wastewater Treatment
 Plant in June 2001 (City of Cape Canaveral, 2001) revealed that the survival rate of
 Ceriodaphnia dubia ranged from 85% to 95% for undiluted treated wastewater. The
 survival rate for C. leedsi was 100% for all tests. While the data were limited, this
 indicates that the AWT-treated wastewater is not acutely toxic.

 There is no direct evidence (such as the use of tracer studies) that indicates that
 constituents in AWT-treated wastewater are taken up by aquatic biota or human receptors
 in the coastal embayments or canals reviewed. However, although there is no direct
 evidence, indirect evidence indicates that discharges of treated wastewater do affect water
 quality on a regional scale. Zhou and Rose (1995) and City of Tampa Bay Study Group
 (2000b) reported that water quality in Sarasota Bay and Hillsborough Bay (Tampa Bay)
 improved after wastewater treatment plants that discharged to rivers or the bay itself
 upgraded their wastewater treatment to meet tertiary or advanced standards. This suggests
 that the high nutrient levels previously measured in the bay were at least partly the result
 of discharges of secondary-treated effluent.

 Some potential ecological receptors, such as endangered species, may be more
 susceptible to harm and may be at risk from concentrations less than the applicable
 standards. Additionally, eutrophication is site-specific as it is greatly influenced by
 physical and biological processes. Addition of nutrients and, indeed, any constituents that
 may be present in treated effluent needs to be examined in a site-specific context to truly
 evaluate risk.

 Little information was found on ecological receptors in canals that may be receiving
 wastewater effluent. However, estuaries  examined in this study that are receiving treated
 wastewater contain marine mammals, fish, and birds that are known to be at risk from
 other effects of human development.

 In terms of the applicable water-quality standards, surface waters receiving discharges of
 treated wastewater reviewed in this report were designated as Class III waters. Class III
 water-quality standards are meant to protect a healthy population of fish and wildlife and
provide recreational uses. Compared to these standards, the quality of AWT effluent was
 often well below the required minimum concentrations.

Physical mixing and dilution are important large-scale processes that will act to decrease
 concentrations of stressors in a water body. This is especially true for streams, rivers,
 estuaries,  and coastal embayments that are well mixed. Such dispersion and dilution will
 decrease the risks to human and ecological receptors.

There is a strong coupling of groundwater and surface water in South Florida. At present,
there are few estimates of the hydrologic fluxes between groundwater and surface water
 in south Florida. However, in recent studies in the Everglades, it was found that extensive
                                       7-23

-------
human manipulation of the natural drainage system in southern Florida has altered
hydrology that has led to increased recharge and discharge in the north-central
Everglades (USGS, 2002). Additional evidence of interaction between groundwater and
surface waters in the Everglades was provided when mercury was found to be recharged
from surface water to groundwater and stored in the surficial aquifer. Indeed two-way
exchange of surface water and groundwater may be a localized phenomenon, as was
found in Taylor Slough (USGS, 2002).

Canals, which are a frequent receptor for discharge of treated wastewater into surface-
water bodies, are often hydrologicly connected to groundwater and are recharged by
groundwater. Adams (1991) examined water in the surficial aquifer and canals in Martin
and Palm Beach counties and concluded that groundwater quality did not seem to be
affected by canal water. This suggested that the aquifer is discharging to the canal rather
than the canal recharging the aquifer. However, water from canals may enter the surficial
aquifer when canals are used as an irrigation source. Drinking-water receptors may be
exposed where surface waters have a direct hydrologic connection to the groundwater
resource.

7.7    Final Conceptual Model of the Discharge-to-Surface-Waters Option

This disposal option presents limited risks, because the volumes of treated effluent
discharged to surface water  are much smaller than volumes discharged via ocean outfalls
or Class I injection wells and because the discharges are typically discharged
intermittently.

   •   The degree and kind of treatment of wastewater is an important factor
       determining effluent quality and therefore risk. To discharge to surface waters in
       the state of Florida, wastewater treatment plants are likely to treat using AWT.
       AWT treats wastewater to a higher standard than  secondary treatment, removing
       additional nutrients,  organic compounds, and total suspended solids from the
       effluent.
   •   Several of the AWT standards (for example, nutrients) are elevated when
       compared to natural  background levels of these compounds in unimpacted surface
       waters and when compared to the EPA's recommended standards for unimpacted
       surface waters, which are based on monitoring of more pristine water bodies.
       Nutrients, both nitrogen and phosphorus, pose ecological risks for the aquatic
       environment as they may increase primary production, alter phytoplankton
       communities, and encourage or exacerbate the growth of harmful algal blooms.
       The data available reveal that wastewater treatment facilities often have the ability
       to remove nitrogen to well below the standard required, which would reduce risk.
       While phosphorus met treatment standards, the concentrations that remain in
       treated wastewater are often higher than recommended water-quality standards,
       based on unimpaired waters.
   •   There is a lack of water-quality monitoring data and tracer studies that would
       show whether effluent constituents are taken up by receptors.
                                      7-24

-------
There are no effluent or surface-water quality standards for Cryptosporidium and
Giardia^ although the Florida DEP has recommended that numerical standards
corresponding to a 1 in 1(T4 human illness risk be adopted for Cryptosporidium
and Giardia in reclaimed water (York et al., 2002). These recommendations are
5.8 oocysts per 100 L and 1.4 cysts per 100 L for Cryptosporidium and Giardia^
respectively. For comparison, background concentrations oi Cryptosporidium
oocysts in North American water bodies, such as lakes, rivers, springs, and
groundwater, averaged 44, 43, 4, and 0.3 oocysts per 100 L, respectively (York et
al., 2002).
Concentrations of pathogenic microorganisms in treated wastewater from the
Howard F. Curren facility were well below the standards for discharges to surface
waters for Class III waters. Concentrations of the pathogenic protozoans Giardia
and Cryptosporidium in effluent from the Howard F. Curren AWT plant were
very low.
Monitoring of pathogenic protozoans at other wastewater treatment facilities in
Florida indicates that a few facilities do not meet the recommended limit of 5.8
per 100 L, despite the fact that filtration is done (York et al., 2002). While human
health risks from pathogenic protozoans are generally very low, they are not zero.
Facilities that nitrify appear to be better at removing Giardia than facilities that do
not nitrify (York et al., 2002).
All inorganic compounds, including nutrients and metals, measured in AWT
effluent were below drinking-water-quality standards. Copper was used as a
surrogate because of its known toxicity in the aquatic environment. Copper
concentrations in treated wastewater met Florida water-quality standards.
Measured organic compounds, which include trihalomethanes, synthetic organics,
and volatile organics, were below drinking-water standards. All synthetic and
VOCs were below detection limits for the data reviewed in this study. Two grab
samples for estrogen equivalence (hormonally active agents) revealed that these
constituents are present in the effluent in relatively small concentrations (on the
order of ng/L). Despite the lack of information on in situ concentrations,
hormonally active agents pose ecological risks for aquatic ecosystems because of
information from studies of their effects on other aquatic organisms elsewhere
and because the effects are observed at very low concentrations.
Toxicity testing of AWT effluent revealed no toxicity to aquatic organisms. The
limited data available suggests that AWT effluent poses little or no ecological or
human health risks.
The relative risk of AWT-treated wastewater  is lower than the risks posed by
lesser-treated wastewater, based on improvement of water quality in Tampa Bay
after AWT was required.
Despite the relative lack of monitoring information from surface-water disposal
outfalls and lack of evidence of adverse effects, it is reasonable to assume that,
given the already-impacted nature of many surface-water bodies in South Florida,
further discharge of nutrients in treated wastewater poses some ecological risks.
The potential effects of nutrients on surface-water bodies will vary, depending on
site-specific characteristics and the existing nitrogen loading from other sources.
Preferably, a water-quality-based effluent limit (such as total maximum daily
                                7-25

-------
       loading) would be established that takes into account these site-specific
       characteristics and the carrying capacity of an individual surface-water body.
    •   In some areas, depending on existing impairment of water quality, it may be
       worthwhile to consider whether discharge of treated wastewater could help restore
       hydrology or water quality.

7.8    Gaps in Knowledge

Possible gaps in knowledge and their possible effects on this risk analysis are
summarized below.

    •   The benefits or detriments of discharging A WT-treated wastewater into natural
       systems have yet to be proven.
    •   One of the most important gaps in knowledge concerns the numbers and
       significance of unperrnitted, inadvertent, or occasional unplanned discharges of
       untreated or secondary-treated wastewater to surface-water bodies. Such
       discharges may occur at treatment facilities when storms or other causes combine
       to produce wastewater volumes that cannot be treated rapidly enough to keep up
       with incoming volumes.  Rapid  infiltration basins receiving untreated or secondary
       treated wastewater that overflow to nearby surface-water bodies, such as canals or
       creeks, provide examples of such untreated or minimally treated discharges. Such
       discharges are believed to occur at a number of South Florida facilities, including
       those at Miami-Dade South Treatment Facility. Although such discharges are
       outside the scope of this  study because they are not a permitted form of
       wastewater management, they nonetheless pose high risks.
    •   The potential and actual  human health and ecological health effects  of exposure to
       AWT-treated effluent that has not been filtered to remove pathogenic protozoans
       to the levels recommended by the Florida DEP have yet to be determined. The
       ecological effects of pathogenic protozoans are only beginning to be documented;
       the latest example involves the  implication of Crytosporidium and
       Microsporidium in mortality of manatees along the Gulf coast of Florida.
    •   Distinguishing between other sources of wastewater stressors and those derived
       directly from AWT-treated wastewater will be difficult unless specific tracers are
       utilized in studies designed specifically to distinguish different sources. Many
       other sources of stressors already have adversely affected Florida's surface waters
       and coastal waters.
    •   The effects of discharging wastewater treated to AWT standards into water bodies
       that are already adversely affected have not been explored or documented,
       according to available information. Comparing AWT-treated wastewater with
       water-quality recommendations based on pristine or unaffected ambient Florida
       waters also raises water-management questions that can only be answered through
       a  combination of public process and scientific studies of the fate of these stressors
       and the capacity of the watershed or embayment to assimilate stressors without
       experiencing adverse effects.
                                       7-26

-------
REFERENCES

Adams KM. 1991. Chemical Characteristics of Water in the Surftcial Aquifer System and
       Major Canals, Martin and Northern Palm Beach Counties, Florida, Boca Raton:
       Environmental Geochemistry Florida Atlantic University.

Adams AW, Ainsley JD, Busby DS, Day RA, Recore KA, Rice TB. 1996. The Indian
       River Lagoon Comprehensive Conservation And Management Plan.

Bianchi TS, Pennock JR, and Twilley RR. 1999. Biogeochemistry of Gulf of Mexico
       Estuaries. Ontario: John Wiley & Sons, Inc.

Billen G, Lancelot C, and Meybeck M. 1991. Nitrogen, phosphorus, and silicon retention
       along the aquatic continuum from land to ocean. In: Ocean Margin Process in
       Global Change. Mantoura RFC, Martin JM, and Wollast R, eds. New York:
       Wiley.

Boesch DF, Anderson DM, Horner RA, Shumway SE, Tester PA, and Whitledge TE.
       1996. Harmful Algal Blooms in Coastal Waters: Options for Preservation,
       Control and Mitigation. NOAA Coastal Ocean Program Division Analysis Series
      No. 10. Silver Spring (MD): NOAA  Coastal Ocean Office.

Boyer JN, Fourqurean JW, and Jones RD. 1997. Spatial characterization of water
       quality in Florida Bay and Whitewater Bay by multivariate analysis: Zones of
       similar influences (ZSI). Estuaries. 20: 743-758.

Brewster-Wingard GL, and Ishman SE. 1999. Historical trends in salinity and
      substrate in central Florida Bay: a paleoecological reconstruction using modern
      analogue data. Estuaries. 22(2B):369-383.

Brewster-Wingard GL, Ishman SE, Willard  DA, Halley RB, Holmes CW.
       1996. The Biotic Record of Change in Florida Bay and the South Florida
      Ecosystem. Internet: http://sofia.usgs.gov/projects/eh_fbswc/ehfbswcabfb96.html.

Burnett WC and Schaeffer OA. 1980. Effect of ocean dumping on 13C/12C ratios in
      marine sediments from the New York Bight. Estuarine and Coastal Marine
      Science. 11:605-611.

Camp, Dresser, McKee, Inc. 1992. Point-/Nonpoint Source Pollution Loading
      Assessment. Phase I. Final Report. Sarasota (FL):  Sarasota Bay National Estuary
      Program.

City of Cape Canaveral. 2001a. NPDES Monitoring Database 1999-2001. Permit number
      FL0020541
                                     7-27

-------
           . 200 Ib. Report of aquatic toxicity test results. Samples of final effluent
       collected on June 12 and 13 2001. Contact Yvette Manigan.

City of Tampa Bay Study Group, 2001a. Results of the City of Tampa surface water
       compliance monitoring program for the year 2000 ana" examination of long-term
       water quality and biological indicator trends in Hillsborough Bay, Submitted to
       the Florida Department of Environmental Protection Southwest District.

	.2001b. Seagrass and Caulerpa monitoring in Hillsborough Bay twelfth
       annual report. Submitted to the Florida Department of Environmental Protection
       Southwest District.

City of Tampa, Florida. 2001. Howard F. Curren Advanced Wastewater Treatment Plant.
       Internet: http://www.tampagov.net/dept_sanitary_sewers/sitemap/plantO 1 .asp.

Codispoti LA. 1989. Phosphorus vs. nitrogen limitations of new and export production.
       In: Productivity of the Ocean: Present and Past. Berger WH, Smetacek V, and
       Wefer G, eds. New York: Wiley..

Corredor JE, Howarth RW, Twilley RR, and Morrell JM. 1999. Nitrogen cycling and
       anthropogenic impact in the tropical interamerican seas. Biogeochemistry.
       46(1/3):163-178. Cited.

Day JW, Hall CA, Kemp WM., and Yanez-Arancibia, A. 1989. Estuarine Ecology.
       Ontario: John Wiley & Sons.

Dugdale RC. 1967. Nutrient  limitation in the seas: dynamics, identification, and
       significance. Limnology & Oceanography. 12:685-695.

Ehrhart LM and Redfoot WE. 1995. Composition and status of the marine turtle
       assemblage of the Indian River Lagoon System. Bulletin of Marine Science.
       57:279-280.

Englehardt JD, Amy VP, Bloettscher F,  Chin DA, Fleming LE, Gokgoz S, Rose JB,
       Solo-Gabriele H, and Tchobanoglons G. 2001. Comparative Assessment Of
       Human And Ecological Impacts Form Municipal Wastewater Disposal Methods
       In Southeast Florida. University of Miami. Submitted to the Florida Water
       Environmental Association Utility Council.

Eppley RW, Renger EH, and Harrison WG. 1979. Nitrate and phytoplankton production
       in southern California coastal waters. Limnology and Oceanography. 24(3): 483-
       494.

Facemire CF, Gross TS, and  Guillette Jr., LJ. 1995. Reproductive Impairment in the
       Florida Panther: Nature or Nurture? Environmental Health Perspectives.
       103(Suppl4):79.
                                     7-28

-------
 Feacham RG, Bradley DH, Garelick H, and Mara DD. 1983. Sanitation and Disease
        Health Aspects of Excreta and Waste-water Management. New York: Wiley.

 Finney BB and Huh CA. 1989. History of metal pollution in the Southern California
        Bight: an update. Environmental Science & Technology. 23:294-303.

 Flegal AR, Sanudo-Wilhelmy SA, and Scelfo GM. 1995. Silver in the eastern Atlantic
        Ocean. Marine Chemistry. 49:315-320.

 [FDEP] Florida Department of Environmental Protection. 2002a. Water Reuse: Reuse
        Statutory Authority. Internet: http://www.dep.state.fl.us/water/reuse/statauth.htm.

 	. 2002b. Wastewater Treatment Facilities Reports. Internet:
 http://www.dep.state.fl.us/water/wastewater/download.htm.

 Forstner U and Wittmann GTW. 1979. Metal Pollution In The Aquatic Environment.
        Berlin: Springer.

 Gilmore RG. 1995. Environmental and biogeographic factors influencing icthyofaunal
        diversity: Indian River Lagoon. Bulletin of Marine Science. 57(1): 153-170.

 Gilmore RG, Donahoe CJ, Cooke DW, and Herema DJ. 1981. Fishes of the Indian River
        Lagoon and adjacent waters, Florida. Technical Report No. 41. Ft. Pierce (FL):
        Harbor Branch Foundation.

 Grossfield S. 2002. Sewage Helps to Kill off Manatees, Biologist Says. The Boston
        Globe. 5 April 2002.

 Hazen and Sawyer. 1994. SEFLOEII Final Report: Braward County Office of
        Environmental Services North Regional Wastewater Treatment Plant, City of
        Hollynvood Utilities Department Southern Region Waste-water Treatment Plant,
        Miami-Dade Water and Sewer Department North District Wastewater Treatment
        Plant, Miami-Dade Water and Sewer Department Central District Wastewater
        Treatment Plant. Hollywood (FL): Hazen and Sawyer. Submitted to National
        Oceanic and Atmospheric Administration.

Hershelman GP, Schafer HA, Jan TK, and Young DR. 1981. Metals in marine sediments
        near a large California municipal outfall. Pollution Bulletin. 12:131-134.

 Hoffman BA.  and Haddad  KD. 1998. General land use and vegetation changes in the
        Indian River Lagoon System. In: Indian River Lagoon Estuarine Monograph
        (Draft). Barile DD, ed. Melbourne (FL): Marine Resources Council of East
        Florida, Florida Institute of Technology.

 Howarth RW. 1988. Nutrient limitation of net primary production in marine ecosystems.
       Annual Review of Ecology and Systematics. 19:89-110. Cited.
                                      7-29

-------
Howarth RW, Jensen HS, Marino R, and Postma H. 1995. Transport to and processing of
       phosphorus in near-shore and oceanic waters. In: Phosphorus in the Global
       Environment. Tiessen H, ed. New York: Wiley.

Huh CA, Finney BP, and Stull JK. 1992. Anthropogenic inputs of several heavy metals to
       nearshore basins off Los Angeles. Progress & Oceanography. 30:335-351.

Huntzicker JJ, Friedlander SK, and Davidson CI. 1975. Material balance for automobile-
       emitted lead in Los Angeles Basin. Environmental Science Technology. 9:448-
       457.

Kapadia A and Swain ED. 1996. Quantifying Freshwater Discharge for Coastal
       Hydraulic Control Structures in Easter Dade County, Florida. South Florida
       Ecosystem Program. Reston (VA): USGS.

Klein HH  and Goldberg ED. 1970. Mercury in the marine environment. Environmental
       Science Technology. 4:765-768.

Larsson DGL, Adolfsson-Erici M, Parkkonen J, Pettersson M, Berg AH,  Olsson PE, and
       Forlin L. 1999. Ethmyloestradiol - An undesired fish contraceptive. Aquatic
       Toxicology. 45: 91-97.

Lietz AC.  2000. Nutrient transport to Biscayne Bay and water-quality trends at selected
       sites in South Florida. In: USGS Program on the South Florida Ecosystem: 2000
       Proceedings. OFR 00-449. Reston (VA): USGS.

Lipp EK, Farrah SA, and Rose JB. 2001. Assessment and impact of microbial fecal
       pollution and human enteric pathogens in a coastal community. Marine Pollution
       Bulletin. 42(4): 286-293.

Malone TC, Conley DJ, Fisher TF, Gilbert PM, Harding LW, and Sellner KG. 1996.
       Scales of nutrient-limited phytoplankton productivity. Chesapeake Bay. Estuaries.
       19:371-385.

MarellaRL. 1999. Water withdrawals, use, discharge, and trends in Florida, 7P95.USGS
       Water Resources Investigations Report 99-4002. Talahassee (FL): USGS in
       cooperationwith the Florida Department of Environmental Protection.

Matthai C  and Birch GF. 2000. Trace metals and organochlorines in sediments near a
       major ocean outfall on a high energy continental margin (Sydney, Australia).
       Environmental Pollution. 110: 411-423.

McPherson BF and Halley R. 1996. The South Florida Environment - A region under
       stress. U.S. Geological Survey Circular, 1134.
                                     7-30

-------
McPherson BF, Miller RL, Haag KH, and Bradner A. 2000. Water quality in Southern
       Florida, 1996-1998. U.S. Geological Survey Circular, 1207.

Morel FMM, Westphal JC, O'Melia CR, and Morgan JJ. 1975. Fate of trace metals in
       Los Angeles County wastewater discharge. Environmental Science & Technology,
       9:756-761.

Myers VB and Iverson RL  1981. Phosphorus and nitrogen limited phytoplankton
       productivity in northeastern Gulf of Mexico coastal estuaries. In: Estuaries and
       Nutrients. Nielson GJ and Cronin LE, eds. New York: Humana Press.

[NOAA] National Oceanic  and Atmospheric Administration. 1999. Florida Bay and
       Adjacent Marine Systems Science Program Overview. Internet:
       http://www.aoml.noaa.gov/flbay.program_overview.html.

National Research Council. 2000. Clean Coastal Waters: Understanding and Reducing
       the Effects of Nutrient Pollution.

Nichols KM, Miles-Richardson SR, Snyder EM, Giesy JP.  1998. Effects of exposure to
       municipal wastewater in situ on the reproductive physiology  of the Fathead
       Minnow (Pimephales Promelas). Environmental Toxicology and Chemistry.
       18(9):2001-2012.

Paerl HW. 1997. Coastal eutrophication and harmful algal looms: importance of
       atmospheric deposition and  ground water as "new" nitrogen and other nutrient
       sources. Limnology  & Oceanography. 42(5 part 2): 1154-1165.

Paul JH, Rose JB, Brown J, Shinn E, Miller S, and Farrah S. 1995. Viral tracer studies
       indicate contamination of marine waters by sewage  disposal practices in Key
       Largo, Florida. Applied and Environmental Microbiology. 61:2230-2234.

Penrose W, Conacher H, Black R, Maranger J, Miles W, Cunningham H, and Squires W.
       1977. Implications of Inorganic/Organic Interconversion on Fluxes of Arsenic in
       Marine Food Webs. Environmental Health Perspectives. 19:53-59.

Pritchard D. 1967. Observations of circulation in coastal plain estuaries. In: Estuaries.
       Lauff G, ed. Publication No. 83. Washington (DC):  American Association for the
       Advancement of Science.

Pribble RJ, Janicki AJ, and  Greening H. 1999. Baywide environmental monitoring report
       1993-1998. Technical Report #07-99. Tampa Bay Estuary Program.

Rabalais NN, Turner RE, Justic D, Dortch Q, and Wiseman Jr. WJ. 1999.
       Characterization ofHypoxia: Topic, Report for the Integrated Assessment of
      Hypoxia in the Gulf of Mexico. NOAA Coastal Ocean Program. Decision
      Analysis Series No.  15. Silver Spring (MD): NOAA Coastal Ocean Program.
                                     7-31

-------
Randazzo AF and Jones DS. 1997. The Geology of Florida. Gainesville: University Press
       of Florida.

Ravizza GE and Bothner MH. 1996. Osmium isotopes and silver as tracers of
       anthropogenic metals in sediments from Massachusetts and Cape Cod Bays.
       Geochimica Cosmochimica Acta. 60:2753-2763.

Roat P and Alderson M. 1990. Sarasota Bay Project: State of the Bay Report. Sarasota
       (FL): Sarasota Bay National Estuary Program.

Robertson LJ, Campbell AT, and Smith HV. 1992. Survival of Cryptosporidium parvum
       oocysts under various environmental pressures. Applied and Environmental
       Microbiology. 58: 3494-3500.

Rodgers-Gray TP, Jobling S, Morris S, Kelly C, Kirby S, Janbakhsh A, Harries JE,
       Waldock MJ, Sumpter JP, and Tyler CR. 2000. Long-term temporal charges in
       the estrogenic composition of treated sewage effluent and its biological effects on
       fish. Environmental Science & Technology. 34(8):1521-1528.

Ryther JH and Dunstan WM. 1971. Nitrogen, phosphorus and eutrophication in the
       coastal marine environment. Science. 171:1008-1112.

Sadik O, and Witt DM. 1999. Monitoring endocrine-disrupting chemicals. Environmental
       Science and Technology, pp. 368A-374A.

Sarasota Bay National  Estuary Program.  1993. Sarasota Bay: Reclaiming paradise: A
       report to the people from the Sarasota Bay National Estuary Program.

	. 2000. State of the Bay, 2000. Another day in paradise.
Schindler DW. 1977. Evolution of phosphorus limitation in lakes. Science. 195: 260-262.

	. 1978. Factors regulating phytoplankton production and standing crop in the
       world's freshwaters. Limnology and Oceanography. 23(3): 478-486.

Sellner KG. 1997. Physiology, ecology, and toxic properties of marine cyanobacteria
       blooms. Limnology & Oceanography. 42(5 part 2):1089-1104.

Smith VH. 1982. The nitrogen and phosphorus dependence of algal biomass in lakes: An
       empirical and theoretical analysis. Limnology & Oceanography. 27(6):1101-1112.

Steidinger KA, Roberts BS, Tester PA, Tomas CR, and Vargo GA. 1996. Red Tide
       Research Planning A nd Coordination Meeting Repor: Nov. 6- 7. Department of
       Environmental Protection, Florida Marine Research Institute.
                                     7-32

-------
[US EPA] U.S. Environmental Protection Agency. 2000a. Ambient water quality criteria
       recommendations, lakes and reservoirs in nutrient ecoregion XIII. EPA 822-B-OO-
       014. Washington (DC): US EPA.

	.2000b. Ambient water quality criteria recommendations, rivers and streams
       in nutrient ecoregion XII. EPA 822-B-00-021. Washington (DC): US EPA.

[USGS] U.S. Geological Survey. 1996a. South Florida Ecosystems: Changes through
       time. FS-171-95. Reston (VA): USGS.

	. 1996b. Ecosystem history of Florida Bay. FS-144-96. Reston (VA): USGS.
           . 1996c. Ecosystem history : Florida Bay and the Southwest coast. Internet:
       http://sofia.usgs.gov/metadata/sflwww/lbwfbay.html.

	. 2002. Groundwater Surface Water Interactions and Relation to Water
       Quality in the Everglades. Internet: http://sofia.usgs.gov/projects/wtr_flux/

Valette-SilverNJ, Riedel GF, Crecelius EA, Windom H, Smith RG, and Dolvin SS.
       1999. Elevated arsenic concentrations in bivalves from the southeast coasts of the
       USA. Marine Environmental Research. 48:311-333.

Woolson E. 1977. Fate of Arsenicals in Different Environmental Substrates.
       Environmental Health Perspectives. 19:73-81.

York DW, Menendez P, and Walker-Coleman L. 2002. Pathogens in reclaimed water:
       The Florida experience. 2002 Water Sources Conference.

Zhou X and Rost JB. 1995. Phillippi Creek Water Quality Report. Sarasota (FL): Report
       to the Sarasota County Commissioners.
                                     7-33

-------
[ This page intentionally left blank ]

-------
8.0    RELATIVE RISK ASSESSMENT

This chapter presents the findings of EPA's relative risk assessment for the South Florida
municipal wastewater management options: deep-well injection, aquifer recharge,
discharge to ocean outfalls, and discharge to surface-water bodies. The preceding
chapters outlined the overall framework for the risk assessment and the application of
that framework to the individual assessments of the South Florida municipal wastewater
treatment options. The main issues that were considered when assessing the risk are
summarized in this chapter, followed by an examination of the human health risks and
the ecological health risks.

Although the term option, used to describe the wastewater treatment methods, suggests
any of these are available for use by the wastewater treatment plants in South Florida, in
fact most facilities are limited by local conditions as to possible treatment methods.
However, most wastewater treatment facilities do not rely solely on one method but
combine management options to meet the current demands and local conditions.

8.1    Identified Risk Issues

Although all four disposal options deal with municipal wastewater, they differ from each
other in almost every aspect. The option used depends on geographic location, the
underlying geology, final injection point, type of treatment, disinfection level, site-
specific conditions, local needs and constraints, the opportunities for water reuse, and, in
some instances, weather conditions.  Because of this variation, each disposal option has its
own specific stressors (hazards), exposure pathways, receptors, and effects. Also,
parameters that are relevant to one particular disposal option are not necessarily relevant
to the remaining three. As a result, it is not feasible to present strictly quantitative data for
all parameters associated with all options.

Table 8-1 identifies the major issues relevant to assessing risk associated with each of the
four options. This information and data is a summary of the findings from the option-
specific risk assessments that were discussed in detail in Chapters 4 through 7. Although
overall quantitative comparisons are not feasible, the information in the table identifies
key issues and allows the reader to relate these issues between the four wastewater
treatment options. The issues are central to managing wastewater treatment in a way that
limits risk to people and the environment.
                                       8-1

-------
        Table 8-1.     Relevant Risk Assessment Issues for the Four Wastewater Management Options
                   Issue
    Deep-Well Injection
  Aquifer Recharge (RIBs)
  Discharge to the Ocean
    Discharge to Surface
          Waters
        Type of Treatment and
        Level of Disinfection
Secondaiy treatment;
treatment plants must
maintain basic disinfection
capability. (Exceptions such
as Pinellas County use
secondary treatment, high-
level disinfection and
filtration.)
Secondary treatment,
including high-level
disinfection. Meets Florida's
reclaimed-water standards.
Secondary treatment,
including basic disinfection.
Secondary treatment,
including basic disinfection.
Discharge to Class I waters
requires high-level
disinfection. Discharge to
sensitive waters (such as
Tampa Bay) requires
advanced wastewater
treatment (AWT) with
nitrogen removal.	
        Wastewater Constituents
        Remaining After Treatment
        (Stressors)
00
to
Moderate levels of nutrients
(phosphorus, nitrogen);
concentrations typically meet
maximum contaminant levels
(MCLs), but may exceed
surface-water quality
standards (for example, AWT
standards).

Small amounts of metals and
organic compounds;
concentrations typically meet
MCLs (trihalomethanes may
occasionally exceed the
MCL).

Pathogenic protozoans are not
removed; infective bacteria
and viruses remain.
Low levels of nutrients
(phosphorus, nitrogen);
concentrations frequently
exceed AWT standards and
EPA recommendations for
ambient surface-water
quality.

Trace amounts of metals and
organic compounds;
concentrations typically meet
MCLs.

Low mean numbers of
pathogenic protozoans
(occasional instances of
higher numbers); bacteria and
viruses are effectively
inactivated.
Moderate levels of nutrients
(phosphorus, nitrogen).

Trace amounts of metals and
organic compounds;
concentrations typically meet
MCLs. Metals frequently
exceed ambient  seawater
concentrations.

Pathogenic protozoans are not
removed; small numbers of
infective bacteria and viruses
may remain.
Low levels of nutrients.
Nutrient concentrations
typically meet standards
specific to water bodies, but
may exceed EPA
recommendations for ambient
surface-water quality.

Trace amounts of metals and
organic compounds;
concentrations  typically meet
MCLs.

Low numbers of pathogenic
protozoans; bacteria and
viruses are effectively
inactivated.

-------
        Table 8-1.    Relevant Risk Assessment Issues for the Four Wastewater Management Options
                   Issue
                                Deep-Well Injection
                              Aquifer Recharge (RIBs)
  Discharge to the Ocean
    Discharge to Surface
          Waters
        Large-Scale Transport
        Mechanisms
                             Simultaneous upward and
                             horizontal migration. Vertical
                             transport occurs as a result of
                             injection pressure and fluid
                             buoyancy. Horizontal
                             transport in the direction of
                             groundwater flow.
                             Initial downward migration
                             (infiltration, percolation).
                             Horizontal transport in the
                             direction of groundwater
                             flow.

                             Potential for recharge to
                             surface waters.
Initial upward migration into
the ocean water column.
Horizontal transport within
the Florida Current
(northward). Occasional
transport towards the coast.
Downstream (horizontal)
transport in canals. Turbulent
mixing in estuaries and bays.

Potential for recharge where
water body is hydrologically
connected to groundwater.
oo
Distance Between Point of
Discharge and Potential
Receptors
(Note: Depending on the
particular option,  receptors
may be USDWs and drinking-
water supplies, or they may
be human or ecological.)
Injection occurs between
1,000 and 3,000 feet below
ground surface. Vertical
distance to the nearest
overlying USDW varies
geographically:
•   Dade Co.: approx. 1,000
    ft.
•   Brevard Co.: approx. 950
    ft.
•   Pinellas Co.: approx. 570
    ft.

Thousands of feet to water-
supply wells or potential
ecological receptors.	
                                                                  The distances range from tens
                                                                  of feet to hundreds of feet.
Discharge occurs between
roughly 1 and 3.5 miles
offshore. No drinking-water
receptors exist at the ocean
outfall discharge points.

Tens of feet (or more) to
ecological receptors in the
vicinity of outfalls.
Tens of feet to receptors at
discharge point; hundreds of
feet to other receptors.

-------
        Table 8-1.     Relevant Risk Assessment Issues for the Four Wastewater Management Options
                   Issue
    Deep-Well Injection
 Aquifer Recharge (RIBs)
  Discharge to the Ocean
    Discharge to Surface
          Waters
        Time of Travel to Potential
        Receptors
        (Note: Depending on the
        particular option, receptors
        may be USDWs and drinking-
        water supplies, or they may
        be human or ecological.)
CO
Potential receptors are deep
USDWs and current drinking-
water supplies. Vertical times
of travel to these receptors
vary geographically:
• Dade Co.: Between 14 and
  420 years to deep USDWs;
  30 to >1,100 years to the
  depth of current water
  supplies
• Brevard Co.: Between 86
  and 340 years to deep
  USDWs; 136 to >1,100
  years to the depth of
  current water supplies
• Pinellas Co.: Between 170
  days and 2 years to deep
  USDWs; 6 to 23 years to
  the depth of current water
  supplies.

Fluid movement into deep
USDWs confirmed at 3
facilities; probable movement
into USDWs at an additional
6 facilities.
Horizontal tunes of travel
within the surficial aquifers
vary with site-specific
characteristics and with
mandatory setback distances:
• Dade Co.: Approx. 40 days
  to travel 200 feet; 1.5 years
  to travel ₯2 mile
• Brevard Co.: Approx. 3
  years to travel 200 feet; 40
  years to travel l/2 mile
• Pinellas Co.: Approx. 6
  years to travel 200 feet; 75
  years to travel Vz mile.
There are no drinking-water
receptors.

Immediate transport
(minutes) to receptors that
may occur around the
discharge points. Rapid
transport to downstream
ecological receptors (hours to
days); however, there is rapid
attenuation by dilution in the
ocean.
Immediate transport to
receptors around surface-
water outfalls.

Rapid transport to
downstream human and
ecological receptors (hours to
days).

Delayed and variable
recharge to surficial USDWs.

-------
        Table 8-1.     Relevant Risk Assessment Issues for the Four Wastewater Management Options
                   Issue
                                 Deep-Well Injection
                               Aquifer Recharge (RIBs)
  Discharge to the Ocean
    Discharge to Surface
          Waters
        Attenuation Processes
                             Dilution; filtration by porous
                             geologic media; sorption onto
                             media; other chemical
                             degradation processes.
                             Filtration by soils and by
                             porous geologic media;
                             sorption onto soils and media;
                             dilution; microbial
                             degradation; other chemical
                             degradation processes.
Dilution; settling; sorption
onto sediments; biological
uptake and degradation;
photo-oxidation; other
processes.
Dilution; settling; sorption
onto sediments; biological
uptake and degradation;
photo-oxidation; other
processes.
oo
Anticipated Reduction in
Stressor Concentration
(Note: Depending on the
particular option, receptors
may be USDWs and drinking-
water supplies, or they may
be human or ecological.)
Minimally to substantially
reduced before reaching deep
USDWs. Minimal reduction
where estimated times of
travel are short (for example,
Pinellas Co.) or where
groundwater monitoring
indicates rapid vertical fluid
movement (for example,
Miami-Dade, South District).
Moderate to substantial
reduction where estimated
times of travel to USDWs are
long.

Substantially reduced before
reaching the depth of current
water supplies or potential
ecological receptors.  	
                                                                   Minimally reduced before
                                                                   reaching USDWs.

                                                                   Moderately to substantially
                                                                   reduced before reaching other
                                                                   potential receptors.
Minimally to moderately
reduced before reaching
receptors that may occur or
be near points of discharge;
mean dilutions between 60:1
and 90:1 are achieved within
400 meters of the discharge
point.

Substantially reduced before
reaching receptors that may
occur or be at greater
distances from points of
discharge.
Minimally reduced before
reaching receptors near
outfalls.

Moderately to substantially
reduced before reaching
receptors at further distances
from outfalls.

-------
        Table 8-1.     Relevant Risk Assessment Issues for the Four Wastewater Management Options
                   Issue
    Deep-Well Injection
 Aquifer Recharge (RIBs)
  Discharge to the Ocean
    Discharge to Surface
          Waters
        Factors That May Increase
        Risk
oo
The potential for long-term
impacts to USDWs.

Long time frames for
recovery.

The difficulty in performing
remediation in the deep
subsurface.

The lack of attenuation where
conduit flow is a major fluid
movement mechanism.

Instances where there is little
natural straining or filtering
of particulates or
microorganisms.	
The potential for long-term
impacts to USDWs and
current water supplies.

The proximity to drinking-
water and ecological
receptors.
The proximity to ecological
receptors.

The potential for shifts in
current toward shore and
human receptors. This is
currently estimated to occur
approximately 4% of the
time.

The lack of natural straining
(filtration) of particulates or
microorganisms.
The potential for recharge to
surficial USDWs.

The proximity to ecological
receptors.

The potential for long-term
impacts to surface-water
quality.

The lack of natural straining
(filtration) of particulates or
microorganisms.
        Factors That May Decrease
        Risk
Appropriate siting,
construction, and operation of
wastewater treatment plants
and outfalls.
Use of a high level of
wastewater treatment and
disinfection (results in high-
quality wastewater).
The absence of drinking-
water receptors (resulting
from off-shore location for
discharge points).

Rapid, significant dilution
achieved by siting in fast-
moving currents and perhaps
by the use of multiport
diffusers.
Use of a high level of
wastewater treatment and
disinfection.

The absence of drinking-
water receptors (resulting
from little reliance on
surface-water bodies as
sources of drinking water).

-------
        Table 8-1.     Relevant Risk Assessment Issues for the Four Wastewater Management Options
                   Issue
    Deep-Well Injection
 Aquifer Recharge (RIBs)
  Discharge to the Ocean
   Discharge to Surface
          Waters
        Data and Knowledge Gaps
oo
 i
-J
Site-specific mechanisms of
transport (for example,
porous media flow vs.
conduit flow); locations and
connectivity of natural
conduits such as solution
channels.

The fate and transport of
pathogenic microorganisms;
rates of die-off and natural
attenuation.

The extent of, if any,
reduction in inorganic
stressor concentration
resulting from local
geochemical conditions (for
example, rate of biologically
mediated transformation of
ammonia).

Groundwater monitoring data
to describe transport to (or
within) the Biscayne and
surficial aquifers.	
Site-specific hydrologic data
(for example, horizontal
hydraulic conductivities);
site-specific estimates of
horizontal time-of-travel.

Groundwater monitoring data
to describe transport within
the Biscayne and surficial
aquifers.

Geospatial data to describe
proximity to water-supply
wells (especially private
wells).

Fate and transport of
pathogenic micro-organisms
still present after disinfection;
rates and die-off.
The potential for adverse
ecological effects near
outfalls.

The potential for
bioaccumulation (such as
metals, persistent organic
compounds) through food
chains.

Water-quality and ecological
monitoring downcurrent of
outfalls (beyond mixing
zones).

The potential for changes in
ocean currents, sea level, or
climate that might affect
changes hi circulation and
transportation patterns or
exposure.
The potential for adverse
ecological effects near points
of discharge.

The potential for
bioaccumulation (such as
metals, persistent organic
compounds) through food
chains.

Water-quality and ecological
monitoring data for specific
potentially impacted water
bodies.

The nature and extent of
recharge to surficial USDWs.

-------
8.1.1   Wastewater Treatment and Disinfection

The four disposal options are generally associated with four different types of treatment
and disinfection levels (Table 8-1). The type of treatment and level of disinfection given
the wastewater before disposal, discharge, or recharge are the most important issues that
affect risk. The treatment and disinfection determine the  constituents that remain after
treatment and therefore the potential stressors in the wastewater to be discharged.

The type of treatment and level of disinfection are factors that can be prescribed and
controlled through management. This is in contrast to factors that are related to physical
setting and natural processes and that are largely beyond the control of plant operators
and risk managers. State and Federal laws require different minimum types of treatment,
depending on the final disposal method. Although plant operators can opt to provide
treatment beyond the minimum required, it is not usually practical.

Advanced wastewater treatment (AWT) is the highest level of wastewater treatment
conducted in South Florida and poses the fewest risks to human health or ecological
values. It combines several treatments and results in water that meets water-quality
standards for receiving water bodies and also, for the most part, meets drinking-water
standards. AWT includes secondary treatment, basic disinfection, filtration, high-level
disinfection, nutrient removal, and removal of toxic compounds. Wastewater discharged
to Tampa Bay, Sarasota Bay, and other already-impaired surface-water bodies must be
treated to AWT levels (Table 8-1).

Treated wastewater bound for aquifer recharge and for discharge to Class I surface waters
undergoes secondary treatment and high-level disinfection. This reclaimed water may
contain small amounts of nitrogen and phosphorus and trace amounts of other inorganic
and organic constituents.

Secondary treatment with basic  disinfection represents a third and lower level of
treatment (Table 8-1). This type of treatment and level of disinfection represent the
minimum standard required of most wastewater treatment facilities in South Florida.
Secondary treatment generally results in water of a quality that  may often meet drinking-
water standards in terms of chemical constituents but that still contains moderate amounts
of nutrients (nitrogen and phosphorus) and small amounts of inorganic and organic
compounds. However, basic disinfection may not achieve drinking-water standards for
fecal coliform bacteria (nondetection). Because filtration is not provided, pathogenic
protozoans, such as Cryptosporidium, Giardia, and other chlorine-resistant
microorganisms may remain in the treated wastewater. Secondary treatment with basic
disinfection is provided for wastewater destined for ocean outfalls.

In Florida, secondary treatment without disinfection is used when wastewater is
discharged to deep-injection wells. This lowest level of treatment poses the highest
potential risks (Table 8-1). Moderate amounts of nutrients and microorganisms may
remain in this treated wastewater.

-------
 8.1.2  Large-scale Transport Processes

 Large-scale transport processes represent another important factor in assessing risk. They
 include the physical processes of advection (large-scale mixing) and of dispersion and
 diffusion (small-scale movements of water and diluted constituents). Dilution occurs as a
 result of dispersion, advection, and diffusion. Concentrations of wastewater constituents
 decrease as dispersion and dilution occur in the receiving water body. The receiving
 water may be groundwater (deep-well injection and aquifer recharge), the ocean
 (discharge to the ocean), or surface-water bodies (discharge to surface waters) (Table
 8-1). The relative effects of large-scale transport are likely more significant for
 discharges to the ocean, where there is rapid dilution in the Florida Current, than to deep-
 well injection and aquifer recharge, where transport is through porous rock media.
 However, regardless of the medium, large-scale transport processes have a role in the
 level of risk associated with each of the four wastewater treatment processes.

 8.1.3  Distance and Time Separating Discharge Points and Potential Receptors

 The physical separation (distance between the point at which effluent is discharged into
 the environment and the potential human or ecological receptors or drinking-water
 receptors) is another important factor when assessing risk.  Like the type of treatment and
 level of disinfection used, the physical separation of discharge points from the potential
 receptors is under the control of risk managers and can be adjusted through careful
 planning and siting  of treatment plants and of the associated discharge points. However,
 in many cases, it is not feasible for the risk manager to manipulate the factors affecting
 time and distance to reduce risk. For example, increasing the distance to potential
 receptors may be difficult or impossible for existing treatment facilities.

 The time of travel needed for effluent  water and effluent constituents to reach possible
 drinking-water, human, or ecological receptors is related to the  distance, the nature of the
 environment through which the effluent must travel, and the nature of the stressors
 remaining in the effluent. In general, the longer the time of travel and the greater the
 distance the effluent must migrate, the lower the risk. However, if problems are identified
 in a given situation, long times of travel may mean that the benefits of corrective actions
 will not be realized  for some time.

 In general, higher relative risks are related to fast times of travel because of the
potentially rapid exposure of receptors and the limited attenuation that may achieved by
filtering or straining. However, in the case of ocean disposal, where the time of travel
may be almost instantaneous, attenuation by dilution can greatly reduce potential risk.

Direct comparisons  between the distances and times of travel for the four wastewater
treatments options provide no useful assessment of risk because the four options involve
very different processes. As an example, there is virtually immediate transport between
the discharge point and potential receptors for discharge to the ocean or to a surface-
water body, whereas contact between a stressor and a receptor for some deep-well
injection can be on the order of hundreds of years (Table 8-1).
                                        8-9

-------
8.1.4  Attenuation Processes

Attenuation results in a decrease in concentration of wastewater constituents. Depending
on the disposal option being used, attenuation can have a significant role in reducing the
concentrations of effluent constituents, including potential stressors. The attenuation
processes and the degree to which they are effective in reducing concentrations depends
on the media through which the effluent moves and how the constituents interact with
those media.

In the ocean and in surface-water bodies, attenuation processes may include dilution,
microbial and biological processes, photo-oxidation (by natural sunlight) of organic
compounds, inactivation of viruses and bacteria by ultraviolet rays (in sunlight),
adsorption onto sediment or organic particles, and settling of particles containing
adsorbed wastewater constituents (Table 8-1).

In the subsurface, attenuation processes include dilution, adsorption to geologic material,
entrapment or filtration of microorganisms and other constituents, oxidation, reduction,
or other chemical processes that affect the mobility of constituents,  and biological
degradation of organic compounds (Table 8-1). There may be some microbial
transformation (denitrification) of nutrients nearer to the surface, but overall microbial
decomposition or other microbial activities is not expected to be significant.

The highest potential risks are associated with the least attenuation of stressors. Although
all four management options provide attenuation, the least attenuation is probably
associated with deep-well injection. In the absence of information to the contrary, the
subsurface environment may have low rates of biological  and chemical degradation,
compared to surface-water bodies and soils. However, for deep injection wells, all
constituents except nitrate and metals typically decrease to lower levels by the time the
effluent water reaches the USDWs. This is because of the long travel times associated
with deep-well injection.

For deep injection wells in Dade and Brevard counties, the concentrations  of all
constituents except nitrate and metals decrease to lower levels by the time  the effluent
water reaches the drinking-water receptors. Nitrate and metals may  remain at the same
concentration as the discharge point unless local geochemical conditions facilitate
attenuation. In Pinellas County, effluent water may reach drinking-water receptors
because of the short overall vertical travel time. However Pinellas County  uses a higher
level of treatment, and so the initial effluent may have low concentrations  of stressors,
which are further reduced by the time the effluent water reaches receptors.

Microbial survival in the deep subsurface and in groundwater is also an important issue,
because wastewater injected into deep-injection wells is not disinfected or filtered. The
processes involved in microbial survival are not well understood and constitute an
information gap. Inactivation rates for fecal coliforms range up to tens of days for 90%
inactivation (Bitton  et al, 1983; Medema et al., 1997). As a result, the microorganisms
likely cannot survive the months, decades, or years of transport before reaching drinking-
                                       8-10

-------
water receptors. However, there are no studies that examine long-term survival and
transport of microorganisms in the context of deep-well injection. Inactivation times for
pathogenic protozoans, such as Cryptosporidium, may be in a range that would pose a
human health risk if significant numbers of Cryptosporidium were present initially in the
discharged effluent (Table 8-1).

For aquifer recharge, travel times are shorter than for deep-well injection, but the effluent
must travel through soils and, in some cases, surface vegetation. Uptake of potential
stressors by soils and vegetation may constitute an  important attenuation process for
disposal by aquifer recharge. Also, reclaimed water for aquifer recharge does not pose the
same degree of microbial risk as deep-well injection or ocean outfalls because the level of
treatment and disinfection is higher.

Ocean outfalls have designated mixing zones associated with each outfall. Water-quality
standards are usually met for ocean disposal because of the rapid attenuation within the
mixing zone from dilution. Within the mixing zone, the level of stressors may
temporarily exceed standards; however, by the time the effluent reaches the  boundary of
the mixing zone, dilution has reduced the levels of stressors.

Treated wastewater discharged to surface waters generally meets surface-water quality
standards (for Class III waters). In some cases, monitoring data indicate that the
discharged water is of higher quality than the receiving water. Treated wastewater still
contains small amounts of nutrients and other constituents. This is especially significant
for phosphorus, which can stimulate algal blooms in nearshore or brackish environments.
Since high-level disinfection and filtration are provided, risks from pathogenic
microorganisms are very low.

8.1.5  Factors That Contribute To or Diminish  Risk

In general, factors that when present contribute to risk are the same factors that  when
eliminated diminish risk. For example, proximity to human or ecological or drinking
water receptors will increase risk, whereas increasing the distances to or travel times for
these receptors will diminish the risk (Table 8-1). Also, the factors that may  contribute to
risk for one particular disposal option may have no effect on other disposal methods. For
example, a lack of natural straining and filtering by geologic media will increase risk for
deep-well injection when flow is preferentially through cracks, fissures, and cavernous
openings. However, for ocean disposal, this lack of attenuation by natural straining or
filtering may be insignificant as far as human and ecological health effects because of the
dilution of effluent by the ocean.

The major factors that decrease risk are use of a higher degree of treatment, a high degree
of dilution in receiving water, long travel times to receptors, and the ability of the system
to recover quickly if input of wastewater constituents were to decrease or cease. Aquifer
recharge and surface-water discharge are characterized by higher degrees of treatment
and by rapid potential recovery rates. Ocean outfalls and surface-water discharge are
characterized by rapid dilution, more so for ocean outfalls than for surface water
discharges. Class I injection wells are characterized by very long travel times for effluent
                                       8-11

-------
to reach drinking-water receptors in Bade and Brevard Counties (but short travel times in
Pinellas County).

8.1.6  Data and Knowledge Gaps

For all four wastewater disposal options, there is limited site-specific information
concerning potential ecological effects, bioaccumulation of wastewater constituents,
survival and transport of pathogenic microorganisms, and of specific evidence (such as
tracers) that link stressors from disposal options to ecological or biological or human
health effects. The potential effects of local geochemical conditions on fate and transport
of nitrate and metals cannot be assessed with available information.

Table 8-1 lists the major areas where information and data are lacking. Key general areas
where information is needed to better design, manage, and control wastewater treatment
and disposal include the following:

   •  Microbial survival, inactivation, and transportation rates in groundwater
   •  Rates for microbial straining or filtration by geologic media under different flow
       scenarios
   •  Extent of hydrologic connection between groundwater, surface water, and the
       ocean
   •  Definitive tracer studies to conclusively prove that monitored stressors are derived
       from discharged treated wastewater and to conclusively demonstrate the most
       likely transportation pathways
   •  Monitoring ecological or human health effects
   •  Monitoring effects of climate change on large-scale transportation processes.

8.2    Risk Issues Relevant to Human Health

The potential human health risks associated with each wastewater disposal option differ,
but overall they can be considered low (Table 8-2). Just as for the general risk-related
issues discussed above, quantitative comparisons between the four disposal options are
not feasible. However, the information in Table 8-2 identifies key issues for human
health and allows the reader to relate these issues between the four wastewater treatment
options. Of the various human  health stressors identified, pathogenic protozoans
(Cryptosporidium, Giardia) are the most important for all but the surface water option
where high level disinfection is provided. The deep-well injection process is dominated
by porous media flow, long travel times and fine pore spaces may attenuate and retain
microorganisms including protozoans. When wastewater treatment includes filtration, the
risk posed by pathogenic protozoans decreases significantly but does not disappear, partly
because filtration must be maintained at a high level in order to remove protozoans.
When wastewater treatment does not include high-level disinfection or basic disinfection,
the risks posed by viruses and bacteria are significantly higher.
                                       8-12

-------
        Table 8-2.     Relevant Issues for Human Health
                  Issues
    Deep-Well Injection
     Aquifer Recharge
       (using RIBs)
  Discharge to the Ocean
   Discharge to Surface
          Waters
        Human Health Stressors
        Remaining After Treatment
Infective bacteria or viruses
and pathogenic protozoans.

Nitrates and ammonia.
CO
Bacteria and viruses are
effectively inactivated; there
may remain low mean
numbers of pathogenic
protozoans with occasional
instances of higher numbers.

Disinfection byproducts,
such as trihalomethanes,
may remain.
Small numbers of infective
bacteria or viruses may
remain, as well as pathogenic
protozoans (those that can
survive basic disinfection).

Remaining nitrogen and
phosphorus, in excess, can
cause harmful algal blooms,
which are secondary
stressors.

Metals or organic
compounds; these may
bioaccumulate in fish or
shellfish consumed by
humans.
Infective bacteria and viruses
are effectively inactivated;
low numbers of pathogenic
protozoans may remain.

Remaining nitrogen and
phosphorus, in excess, can
cause harmful algal blooms,
which are secondary
stressors.

Metals or organic
compounds; these may
bioaccumulate in fish or
shellfish consumed by
humans.

-------
        Table 8-2.    Relevant Issues for Human Health
                   Issues
    Deep-Well Injection
     Aquifer Recharge
       (using RIBs)
  Discharge to the Ocean
    Discharge to Surface
          Waters
        Treatment Adequacy
oo
Disinfection is not conducted
and so pathogenic bacteria
and viruses are not
inactivated.

Levels of Crypfosporidiitm
and Giardia are uncertain.
This wastewater is usually
not filtered and likely
exceeds the State health-
based limits (reuse limits) for
pathogenic protozoans.
                                      Levels of disinfection
                                      byproducts may rarely exceed
                                      health standards.

                                      Levels of nitrate occasionally
                                      exceed the drinking-water
                                      standard (MCL). Levels of
                                      ammonia meet the EPA
                                      lifetime health-advisory limit;
                                      exceed stringent risk-based
                                      criteria that account for
                                      indoor air exposure. Levels of
                                      regulated metals and organic
                                      compounds typically meet
                                      drinking-water MCLs.	
High-level disinfection
inactivates pathogenic
bacteria and viruses.

Filtration is generally
adequate to remove
Cryptosporidiwn and
Giardia; levels occasionally
exceed health-based limits.

Levels of disinfection by-
products (for example, total
trihalomethanes) or ammonia
may rarely exceed health-
based standards.

Levels of nitrate, regulated
metals, and organic
compounds typically meet
drinking-water MCLs.
Pathogenic bacteria and
viruses are inactivated by
basic disinfection. However,
the levels of bacteria may
occasionally exceed the fecal
coliform limit for recreational
waters (14 per 100
milliliters).

Levels of the pathogenic
protozoans Cryptosporidiwn
and Giardia are uncertain.
This wastewater is usually
not filtered, and so it may
exceed the State health-based
limits (reuse limits).
Levels of nitrate, regulated
metals, and organic
compounds typically meet
drinking-water MCLs.

Nutrient levels (nitrogen,
phosphorus) typically exceed
ambient concentrations.
These nutrients can cause
localized harmful algal
blooms.
AWT inactivates pathogenic
bacteria and viruses.

Filtration is generally
adequate to remove
Cryptosporidiwn and
Giardia; levels are typically
below ambient concentrations
in surface waters.

Levels of disinfection
byproducts (for example,
total trihalomethanes) may
rarely exceed health-based
standards.

Levels of nitrate, regulated
metals, and organic
compounds typically meet
drinking-water MCLs.

-------
        Table 8-2.     Relevant Issues for Human Health
                  Issues
    Deep-Well Injection
     Aquifer Recharge
       (using RIBs)
  Discharge to the Ocean
   Discharge to Surface
          Waters
        Known Significant
        Exposure Pathways
Transport of stressors to deep
USDWs.
Transport of stressors to
shallow USDWs.
No known significant
exposure pathways.
Dermal contact or accidental
ingestion associated with
recreational use of water
bodies.
        Potential Exposure
        Pathways
CO
K—
Ln
Transport of stressors to
shallow USDWs and to
public or private water-
supply wells.

Exposure to significant
stressor concentrations is
unlikely, but depends upon
proximity and site-specific
vertical times of travel.
Transport of stressors to
public or private water-
supply wells.

Exposure to significant
stressor concentrations is
unlikely, but depends upon
drinking water well proximity
and highly variable horizontal
times of travel.
Additional pathways are
associated with other forms
of reuse not discussed here
(such as inhalation exposure
to aerosols created by spray
irrigation).	
Dermal contact or accidental
ingestion associated with
recreational use.

Ingestion of contaminated
fish or shellfish.

Possible stimulation of
harmful algal blooms (that is,
"red tide"); these can increase
algal toxins in marine water
and air.
Recharge to shallow USDWs
and subsequent transport;
exposure to significant
stressor concentrations is
unlikely (pathogens are a
possible exception).

Ingestion of contaminated
fish or shellfish.

-------
        Table 8-2.     Relevant Issues for Human Health
                  Issues
                                 Deep-Well Injection
                                  Aquifer Recharge
                                    (using RIBs)
                                                                  There is incomplete
                                                                  information regarding the
                                                                  presence and numbers of
                                                                  pathogens in reclaimed water.

                                                                  Little is known about the
                                                                  survival and transport of
                                                                  pathogenic microorganisms
                                                                  in the shallow subsurface and
                                                                  surficial aquifers.

                                                                  Extent of surface-water
                                                                  recharge to surficial USDWs.
  Discharge to the Ocean
    Discharge to Surface
          Waters
Data and
Knowledge Gaps
CO
Survival and transport of
pathogenic microorganisms
in the deep subsurface.

Exact means of transport at
specific locations (for
example, porous media flow
versus bulk flow through
conduits).

Rates of biogeochemical
transformation for
conservative compounds
(such as nitrate and
ammonia). This is of
particular relevance in
relatively shallow aquifers.
Downstream monitoring
information from outside of
the mixing zones is not
available.

The potential for changes in
the circulation of ocean
currents is unknown, as is the
subsequent effect changes
may have on transport within
the effluent plume.

Potential for bioaccumulation
or bioconcentration of metals
and persistent organic
compounds is not known or
understood.
Survival and transport of
pathogenic microorganisms
in surface-water bodies and
coastal embayments.

Extent of surface-water
recharge to surficial USDWs.

Potential for bioaccumulation
or bioconcentration of metals
and persistent organic
compounds.

-------
        Table 8-2.     Relevant Issues for Human Health
                  Issues
    Deep-Well Injection
     Aquifer Recharge
        (using RIBs)
  Discharge to the Ocean
   Discharge to Surface
          Waters
        Overall Estimate of Human
        Health Risk
oo
H—
-J
Low where proper siting,
construction, and operation
result in physical isolation of
stressors, with no fluid
movement.

Low where there have been
impacts to deep USDWs;
however, exposure of current
water supplies is unlikely.

Increased risk where short
times of travel prevail and
where exposure of current
water supplies is more likely.
                                      In all cases, the risk would be
                                      further reduced when injected
                                      wastewater is treated to
                                      reclaimed water standards.
Low when treated with high-
level disinfection, filtration,
and treatment to reclaimed-
water standards.

Increased risk where filtration
is not adequate to meet
health-based
recommendations for Giardia
or Cryptosporidium.

Increased risk where
chlorination results in high
levels of disinfection
byproducts (that is, failure to
dechlorinate).
Low because of rapid dilution
and an absence of drinking-
water receptors. The low
probability (less than 4%)
that current flow  is towards
the coast means that human
exposure along coastal
beaches is reduced.

Increased risk where
recreational use is near the
discharge.

Increased risk where
discharges contribute to
stimulation of harmful algal
blooms.
Low when treated with high-
level disinfection and
treatment to AWT standards.

Increased risk where filtration
is not provided or is
inadequate to meet health-
based recommendations for
Giardia or Cryptosporidium.

Increased risk where surface-
water discharges are near
recreational use of water
bodies.

Increased risk where
discharges contribute to
stimulation of harmful algal
blooms.

-------
Other lower-priority human health stressors included nitrate and ammonia associated
with deep-well injection and nitrogen and phosphorus associated with ocean outfalls
(because of the potential for causing harmful algal blooms). Persistent organic
compounds may pose some risks in the deep-well injection option when shorter travel
times occur and when treatment is not adequate to reduce concentrations below the MCL
(Table 8-2).

For aquifer recharge, disinfection byproducts, such as trihalomethanes,  also may be of
concern in reclaimed water that is not dechlorinated (Table 8-2).

Other human health stressors, including metals and organic compounds, are associated
with all options.  For aquifer recharge and surface-water discharge, nutrients are lower-
priority human health stressors, because treatment of wastewater for these options
removes  significant amounts of nutrients.

Wastewater treatment is adequate for metals and most organic compounds to meet
existing regulatory standards and drinking-water MCLs (Table 8-2). However,  there are
no quantitative standards for unregulated substances, such as endocrine disrupters and
detergents, or for Cryptosporidium and other pathogenic protozoans.

8.3    Risk Issues Relevant to Ecological Health

Just as for human health risks, the potential ecological health risks differ, depending on
the option. However, there is somewhat more of a gradation between the different
disposal options  (Table 8-3). The overall risk is likely very low (but probably not zero)
for aquifer recharge, discharge to surface waters, and deep injection wells in Dade and
Brevard counties; low for discharges to the ocean; and moderate for deep injection wells
in Pinellas County.

Nutrients are the major ecological stressors for all four disposal options. Nutrients can
potentially stimulate primary production, and this can lead to eutrophication or other
adverse changes  in community structure. Because of its mobility in groundwater,
nitrogen is the primary nutrient of concern for deep injection wells and  aquifer  recharge.
Phosphorus is not a concern for these disposal options because phosphorus tends to
adsorb quickly to sediment or soil. Nitrogen is also the primary nutrient of concern for
ocean outfalls because it is generally the limiting nutrient for primary production in the
ocean. For discharges to fresh-to-brackish surface water, phosphorus  poses the  greatest
concern because  it is generally limiting in such systems and is not as  quickly immobilized
as it is in soil.
                                       8-18

-------
        Table 8-3.    Relevant Issues for Ecological Health
                  Issue
    Deep-Well Injection
 Aquifer Recharge (RIBs)
  Discharge to the Ocean
   Discharge to Surface
          Waters
        Ecological Health Stressors
        Remaining After Treatment
Nitrogen.

Metals, organic compounds,
phosphorus, pathogenic
micro-organisms.
Nitrogen.

Disinfection by-products.

Metals, organic compounds,
phosphorus, pathogenic
micro-organisms.
Nitrogen and phosphorus.

Metals, organic compounds,
pathogenic micro-organisms.
Nitrogen and phosphorus.

Metals, organic compounds,
pathogenic micro-organisms.
        Treatment Adequacy
oo
Post-treatment nutrient levels
are high enough to pose
potential ecological risks for
surface-water bodies.
However, no off-site ground
water monitoring is
conducted and so actual
subsurface levels are not
known. The presence of
subsurface receptors is also
not known.
Post-treatment nutrient levels
may exceed recommended
levels for unimpacted water
bodies, but are lower than
concentrations in secondary-
treated wastewater and also
lower than some ambient
levels in surface-water
bodies.
Nutrient levels are high
enough to pose potential
ecological risks if dilution
does not occur or if there are
cumulative effects over time.
However, no ecological
monitoring is conducted, and
so individual or cumulative
effects are not understood or
identified.
Nutrient levels may exceed
recommended levels for
unimpacted water bodies.
Discharges to sensitive water
bodies (such as Tampa Bay)
must meet a 3-miIligram-per-
liter limit on total nitrogen (a
70% reduction).

-------
        Table 8-3.     Relevant Issues for Ecological Health
                   Issue
    Deep-Well Injection
 Aquifer Recharge (RIBs)
  Discharge to the Ocean
   Discharge to Surface
          Waters
        Known and Potential
        Exposure Pathways
oo
to
o
Transport of stressors to
surface-water bodies is
feasible, but would occur
over long time frames.

Pinellas County has shorter
times of travel but a higher
level of treatment is used and
so risk is  reduced.
Pathways include contact,
ingestion and inhalation.

Exposure of ecological
receptors may occur in areas
where there is significant
surface water or groundwater
interaction or exchange.
Exposure is most likely
where surface-water bodies
are near RIBs or under direct
influence from groundwater.
Pathways include contact,
ingestion and inhalation.

Fish and other marine
organisms within the mixing
zone are exposed to potential
stressors.

The effects of cumulative or
chronic exposure to elevated
concentrations of some
potential stressors (such as
metals) are not known.
Pathways include contact,
ingestion and inhalation.

Ecological receptors near the
discharge points are exposed
to potential stressors.

Discharges may contribute to
cumulative effects such as
nutrient loading and
bioaccumulation.

Discharges may aggravate
conditions in some surface-
water ecosystems already
under stress.
        Recommended Water
        Quality for Ecological
        Protection
If injectate reaches surface
waters, the nitrate level may
exceed recommended
surface-water levels in the
absence of denitrification in
the subsurface.
Reclaimed water standards do
not meet ecological
protection recommended
standards, but does meet
Florida standards for
receiving waters.
Exceeds the recommended
levels within the allowed
mixing zone (502,655 square
meters). Effluent plume may
occasionally exceed Class El
marine water-quality
standards outside the mixing
zone.
AWT may not be sufficient
for ecological health water-
quality standards, but
otherwise meets Florida Class
in standards for receiving
waters.

-------
        Table 8-3.     Relevant Issues for Ecological Health
                   Issue
    Deep-Well Injection
 Aquifer Recharge (RIBs)
  Discharge to the Ocean
   Discharge to Surface
          Waters
        Data and Knowledge Gaps
Survival and transport of
microorganisms in the deep
subsurface; microbial
transformation processes in
deep subsurface; cumulative
impacts of long-term
disposal.
Impact of aquifer recharge on
groundwater movement and
the transport of existing
groundwater contaminants;
ecological impacts on nearby
wetlands; cumulative and
long-term impacts.
Cumulative impacts of long-
term disposal of nutrients;
ecological impacts or
bioaccumulation of metals or
other compounds in the biota
at or near discharge points;
impact of global climate
change on ocean currents and
effluent dispersal.
Ecological impacts of
nutrient phosphorus or
bioaccumulation of metals or
other compounds in the biota;
cumulative effects.
oo
        Overall Ecological Health
        Risk
The risks from chemical
constituents are low, but not
zero, because of possible
hydrologic connectivity.
Risks related to pathogenic
microorganisms are low to
moderate for Dade and
Brevard counties because of
lack of disinfection and
filtration. Microbial risk is
very low in Pinellas County
because of use of disinfection
and filtration.
Low because of possibility of
hydrologic connectivity
between wetlands and
surficia! aquifer. Cumulative
and long-term effects are not
known.
Low because of the
concentrations of nutrients in
the discharged effluent. No
ecological monitoring is
currently conducted.
Cumulative and long-term
effects are not known.
Low because of the
concentration of nutrients hi
the discharged effluent.

-------
Metals and organic compounds are also ecological stressors for all options. However,
they are considered a lower stressor than nutrients because the information reviewed did
not identify toxic effects over the short-term at either acute or chronic exposure levels.
Pathogenic microorganisms are also considered a lower-priority ecological stressor,
although there is evidence to suggest that aquatic organisms suffer from high
concentrations of enteric microorganisms, just as humans do. The low concentrations of
microorganisms associated with aquifer recharge and discharge to surface water implies
that there probably are few, if any, ecological effects,

8.4    Conclusion

This relative risk assessment analyzed and characterized potential human health and
ecological risks associated with four wastewater management options currently in use in
South Florida. The relative risk assessment emphasized analysis and characterization of
the processes involved in each option and, in particular, of the processes that affect fate
and transport of disposed wastewater effluent. There are many physical, chemical, and
biological factors that affect risk. Their degree of influence varies widely, depending on
the particular disposal option. Some factors can be readily manipulated  and managed to
control or reduce risk.

Each of the four wastewater management options is associated with existing State
programs that have been operating over a period of years and that have  levels of control
focused on the risks posed by that management option. As demonstrated by the range of
information and data presented in the four chapters dealing with the individual options,
each management option for treatment and disposal is extremely complex and can vary,
depending on site-specific conditions and constraints. This makes the task of interpreting
the data and presenting the relative risk assessment very difficult. In spite of this, for all
options, there is either low or  no risk.

There is a decrease in the level of confidence concerning deep-well injection. In some
cases, a lack of confinement of the injected effluent has been confirmed, and the areal
extent of the fluid is unknown. This migration of effluent seems to be associated with
very few site-specific cases but warrants attention. Also, although risks  to ecological
health are also considered low, there are considerable data gaps concerning the biota and
natural systems. Additional or new information and data could provide additional insight
into the actual risks.

For all four wastewater disposal options, the type of wastewater treatment used may be
the most simple factor for comparing the concentrations of stressors that may come in
contact with a receptor. Treatment type and the resulting concentration of stressors is a
risk factor that can be managed. However, the feasibility of using a particular type of
treatment is not equal across the four disposal options.

Another significant issue  for both human and ecological health is the distance that must
be traveled by discharged effluent in order to reach a receptor. The longer the distance
                                       8-22

-------
traveled to a receptor (and the greater the time of travel), the lower the risk. Distance and
the associated travel time is also a risk factor that can be manipulated by risk managers.

Natural attenuation processes can significantly reduce risks in all of the options. The type
and opportunity for attenuation is very specific to the particular disposal option and the
local conditions under which it is used. Natural attenuation processes include filtration by
geologic media, dispersion by groundwater or ocean currents, biological degradation,
adsorption, and photo-oxidation. The distance between the receptors  and stressors and the
resulting travel times are important factors that can further enhance attenuation.

Depending on the geographic location, there are significant differences in hydrogeology,
coastal hydrology, and water quality in South Florida. These site-specific and regional
characteristics can determine whether there is a very low risk or a significant risk. For
example, deep-well disposal in Dade and Brevard counties have long travel times in
comparison to Pinellas County. However, this potential  increased risk for Pinellas County
is ameliorated by providing a higher level of wastewater treatment in Pinellas County. As
another example, the coastal conditions off southeast Florida are favorable for ocean
disposal because the local currents result in rapid dispersion and dilution, whereas the
circulation and water-quality conditions along Florida's Gulf Coast would probably
preclude placement of outfalls.

The relative risk assessment identified major data and knowledge gaps for all of the
disposal options. This is particularly the case for how natural processes may influence
attenuation in deep-well injection and in the extent and nature of ecological impacts. The
relative risk assessment relied on existing information and data and some modeling of
that data. It is clear that for deep-well injection, many issues have never been addressed
because of the belief that there would be no movement of the effluent into USDWs once
the fluid was injected. The confirmation of fluid movement, even in the few cases
reported, reveals that there is much about the pathways, flow, attenuation, and so forth
that is little understood, given the fact that injected fluid can reach USDWs  in some
cases.

For all options, there is very limited information concerning ecological health effects.
Water-quality standards  do not exist for this area, and in many cases, the numbers and
types of receptors may not be known. Also, compared to human health effects,  there is
little information on the impacts of specific stressors on specific populations (such as
zooplankton, fisheries, marine mammals, birds).

Definitive studies are needed to track stressors back to their origins or sources because
there are many potential sources other than wastewater disposal for the same stressors. It
is important to identity and recognize the contributions of various sources of stressors.
Cumulative effects are not well understood for either human or ecological receptors and
may go unrecognized. As more demand develops for additional wastewater treatment
capacity in South Florida, these data and information gaps will likely need to be
addressed so that new facilities can be designed, constructed, operated and maintained
with full confidence that public health and the environment are protected.
                                       8-23

-------
REFERENCES

Bitton G, Farrah SR, Ruskin RH, Butner J, and Chou YJ. 1983. Survival of pathogenic
       and indicator organisms in groundwater. Ground Water. 21:405-410.

Medema GJ, Bahar M, and Schets FM. 1997. Survival of Cryptosporidium parvum,
       Escherichia coli, faecal enterococci and Clostridium perfringens in river water:
       influence of temperature and autochthonous microorganisms. Water Science and
       Technology. 35:249-252.
                                     8-24

-------
DESCRIPTION OF APPENDIX TABLES 1-1 AND 1-2.

1.0    General

Appendix Table 1-1 includes data collected from various sources. These sources include
information compiled in reports by the Florida Water Environment Association Utility
Council and by SEFLOE, as well as sampling data sent directly from the Miarni-Dade
North District Wastewater Treatment Plant and the Brevard County South Beaches
Wastewater Treatment Facility. KEMRON Environmental Services, Inc. provided
sampling data from the Albert Whitted Water Reclamation Facility in St. Petersburg.
The Florida Department of Environmental Protection provided sampling results for the
wastewater treatment facility in the City of Cape Canaveral and the Howard Curren
Wastewater Treatment Plant in Tampa Bay.

1.1    Florida Water Environment Association Utility Council

The Florida Water Environment Association Utility Council (FWEAUC) report
(Englehardt et al., 2001) provided analysis of sampling and monitoring results of effluent
that had been treated to different standards (advanced wastewater treatment, secondary
treatment, and advanced secondary treatment) as well as "native" ambient water in
injection zones and monitoring zones in target aquifers. In all, eight (8) categories of
sampling data were summarized in the Florida Utility Council report. The data that we
present in Appendix Table 1-1 represents "digested" data that has already been processed
by the FWEAUC authors. Those authors include raw concentration data for each of the
sampling stations in appendices B and C of their report. For each of the sampling dates
for each of the stations, the authors provide two lists of monitoring data; the first list
includes the concentrations of all detected constituents and sets each of the "non-detecf
values to zero (0), and the second list duplicates the first, but sets "non-detect" values at
their detection limit. For Each of these two lists, the average concentration of each
parameter was calculated from all of the sampling results at all of the stations within a
category (e.g., advanced wastewater treatment), resulting in average values for each
constituent with non-detects as zero and non-detects at the detection limit, respectively.
Processing the data in this manner has the same effect as assigning values one-half of the
detection limit to all non-detects, a standard approach not inconsistent with risk
assessment methodologies (US EPA. 1998).

The Florida Utility Council study processed all of the raw data in this manner. The
utilities that supplied monitoring data to the authors of the report include:

      *  City of Hollywood
      •  City of Boca Raton
      *  City of Fort Lauderdale
      •  City of Sunrise
      •  City of Boynton Beach
      •  City of West Palm Beach
      •  Broward County North Regional Wastewater Treatment Plant
      •  Miami-Dade County North and South District Wastewater Treatment Plants
      •  Seacoast Utilities
                                      AM

-------
      •   South Central Regional Wastewater Treatment Plant
      •   Florida Governmental Utility Authority (FGUA) Sarasota plants (Southgate and
         Gulf Gate Wastewater Treatment Plants)
      •   The FGUA Golden Gate Plant

1.2    Miami-Bade North District Wastewater Treatment Facility, Dade County

Sampling results from one round of tests characterizing a full suite of waste contaminants
in screen effluent were obtained from the Miami-Dade Water and Sewer (North District)
utility directly (Miami-Dade Water/Sewer Submission # 9903001041). This facility
provides secondary treatment for wastewater effluent before discharging through an
ocean outfall to the Atlantic Ocean. The sampling date for these results is March 19,
1999; this is the same sampling date as the results used in the Florida Utility Council
report; a comparison  of the raw data sent by the facility to the data in the Florida Utility
Council report confirms that this is the same data set. Data from this set were entered
into Appendix Table  1-1 directly; no processing of the data was performed except for the
conversion of values  from mg/L to jag/L (or vice versa). Constituents that were below
the detection limit are indicated in Table 11 with a less than (<) sign preceding  the
reported detection limit.

1.3    South Beaches Wastewater Treatment Facility, Brevard County

Sampling results from one round of tests characterizing a full suite of waste contaminants
were obtained from the Brevard County Water Resources Department (South Beaches
Wastewater Treatment Facility, 2001) for effluent analyses conducted on December 7
and 28, 2000. This facility discharges effluent via a Class I deep injection well, reuse, or
surface water discharge. Wastewater that is discharged through deep well injection
receives secondary treatment.  Water that is reused receives secondary treatment and high
level disinfection with chlorine. Finished water destined for reuse has a concentration of
1 ppm chlorine and is filtered to reduce the concentration of total suspended solids to less
than 5 ppm. Effluent is occasionally discharged directly to the Indian River during heavy
rain and hurricanes. This effluent receives secondary treatment, plus chlorination and
dechlorination as well as nutrient removal to lower the concentration of nitrogen,
phosphorus and chlorine (Chuck Caron, personal communication).

These data represent  single (not averaged) results. Data from this set were entered into
Appendix Table 1-1 directly; no processing of the data was performed except for the
conversion of values  from mg/L to ug/L (or vice versa). Constituents that were below
the detection limit are indicated in Appendix Table  1-1 with a less than (<) sign
preceding the reported detection limit.
1.4    City of St. Petersburg, Albert Whitted Water Reclamation Facility, Pinellas
       County

Sampling results from the Albert Whitted Water Reclamation Facility were obtained by
KEMRON Environmental Services, Inc. The records supplied by Kemron include
effluent monitoring data from a range of dates, as well as minimum, maximum, and
                                      Al-2

-------
average concentrations for each constituent; not all constituents were tested for on all the
dates.  Sampling and analysis occurred on September 16, 1998, January 4, 1999, April 6,
1999, June 29,1999, July 1,1999, September 26, 2000, and January 24, 2001.

Volatile organic constituents, synthetic organic constituents, secondary drinking water
standard regulated constituents, and inorganic constituents were all sampled in September
1998, January and April  1999, September 2000, and January 2001. Radionuclides were
sampled in September 1998, April and June 1999, and September 2000. Trihalomethanes
were sampled in September 2000, and microbes were sampled in January 1999 and
January 2001. Kemron provided constituent concentration data hi two sets: one set of
data included data qualifiers to indicate concentrations that were below detection limits,
and the other set of data had the qualifiers removed in order to calculate the average
concentration of each constituent. The average concentration  of each constituent was
entered directly into Appendix Table 1-1 from the Kemron table lacking qualifiers.
Then, if any of the values used in the calculation had actually  been below the detection
limit, a "less than" (<) sign was added to the value entered into Appendix Table 1-1. For
this reason, a "less than" sign preceding a concentration value does not indicate that the
numeric value is the detection limit. The  "less than" sign simply means that the average
concentration of the constituent in question is less than the value reported in the table.

Ammonia, total nitrogen, total Kjeldahl nitrogen, orthophosphate, and water temperature
were sampled in November 2000; those results  were obtained from a Reclamation
Facility Monitor Well and Effluent Study Report dated December 26, 2000 that was also
provided by Kemron. These single sampling values were added to Appendix Table 1-1.
No processing of the data was performed except for the conversion of values from mg/L
to U£/L (or vice versa).

1.5    City  of Cape Canaveral

The Cape  Canaveral treatment plant serves the City of Cape Canaveral.  In the mid
1990s, the plant was upgraded to an advanced wastewater treatment facility. The plant is
part of a reclaimed water system that supplements the City of  Cocoa Beach's reclaimed
water supply. Discharge to the Banana River, a segment of the Indian River Lagoon,
occurs during wet weather or other periods when reclaimed water demands are low.

The Florida Department of Environmental Protection, Central District, supplied
comprehensive sampling results from a round of sampling at the Cape Canaveral
Wastewater Treatment Plant conducted on October 1, 1999. The City of Cape Canaveral
provided comprehensive sampling results from  analyses conducted on April 3, 2001.
These sampling results were entered into Appendix Table 1-1  directly without processing
other than conversion of concentration units to be compatible with the other records in
the table (i.e., conversion of values from mg/L to  ug/L or vice versa).

In addition, the Florida Department of Environmental Protection (DEP) provided weekly,
monthly, and annual sampling results for constituents that were monitored as part of Cape
Canaveral's compliance with its National  Pollution Discharge Elimination System
(NPDES) permit.  These  constituents include total nitrogen, total phosphorus, and total
suspended solids. These data were provided for calendar  years 1999 through 2001. To
                                      Al-3

-------
supplement the other sampling results for Cape Canaveral (dated October 1999 and April
2001), the annual average of each of the three constituents were calculated from monthly
averages provided in the Florida DEP spreadsheet. Twelve monthly average records
were used to calculate the annual average for each constituent in 1999; however, May
and June 2001 data were unavailable. For this reason, only ten monthly averages were
used to calculate the annual average of each constituent in 2001. Annual averages for
each of these three constituents were included in Appendix Table 1-1 in the Cape
Canaveral 1999 and 2001  columns; superscripted footnote numbers distinguish these
average values from the comprehensive raw data.

1.6    SEFLOE II Data

Concentrations of several parameters in effluent from four wastewater treatment plants
(Broward County North Regional Wastewater Treatment Plant, City of Hollywood,
Miami-Dade North District WWTP, and Miami-Dade Central District WWTP) were
provided in the SEFLOE II report (Appendix Table 1-2) (Hazen and Sawyer, 1994).
Data for ammonia, total Kjeldahl nitrogen, total phosphorus, nitrate, nitrite, and oil and
grease were supplied in that report as arithmetic averages for each utility. These average
values were collected from separate tables and entered into Appendix Table 1-2 in
columns labeled with the utility names (SEFLOE data for Miami-Dade North District are
in a different column than the monitoring data provided by the utility directly). For the
remaining parameters that were analyzed, raw sampling data were provided for each
facility. For example, results from one round of sampling were reported for the City of
Hollywood, results from two sampling dates were reported for each of the Miami-Dade
facilities (February 27, 1991 and February 18, 1992 for North  District and February 22,
1991 and September 20,1991 for  Central District), and results from four sampling dates
were reported for Broward County (February 13,  1991, September 20, 1991, February 11,
1992, and  March 24, 1992). The average concentration for each parameter at each utility
was calculated using these concentration data and excluding data points that were
identified by the SEFLOE authors as "questionable" (i.e., single values for arsenic,
copper, and zinc in Broward County; total silver in the City of Hollywood and Miami-
Dade Central; and heptachlor in Miami-Dade North). In instances where the reported
concentration was "BDL" (Below Detection Limit), no detection limit was reported; for
this reason, a value of zero (0) was used in the calculation of average concentrations.
                                      Al-4

-------
REFERENCES

Caron, Chuck. Plant Supervisor at the South Beaches Wastewater Treatment Facility in
       Brevard County. Personal Communication, July 26,2001.

Englehardt et al. 2001. Comparative Assessment of Human and Ecological Impacts
       from Municipal Wastewater Disposal Methods in Southeast Florida, Table 2.

Hazen and Sawyer, Inc. 1994.  SEFLOE II Final Report. Average values represent 7-43
       sampling records from Broward County North Regional Wastewater Treatment
       Plant, the Miami-Dade North District and Central District Wastewater Treatment
       Plants, and the City of Hollywood Wastewater Treatment Plant, pp. Ill-182-185;
       HI-202-205; and III-210-213.

Miami Dade Water/Sewer, North District. 1999.  Screen effluent collected 3/19/99.
       Monitoring results below detection limits are indicated by showing a less than (<)
       sign preceding the reported detection limit. Submission #9903001041, pp. 47-52.

South Beaches Wastewater Treatment Facility, Melbourne Beach, FL. 2001. Reclaimed
       Water or Effluent Analysis Report, Report Period 1/1/2000 - 12/31/2000.

St. Petersburg, City of, Public Utilities Department, Albert Whitted Water Reclamation
       Facility.

US Environmental Protection Agency.  1998.  Guidance for Data Quality Assessment:
       Practical Methods for Data Analysis EPA QA/G9. QA-97 Version.  Office of
       Research and Development. EPA/600/R-96/084.
                                    Al-5

-------
Appendix Table 1-1.  Drinking Water Standards and Sampling Results for Treated Wastewater and Native Water in South Florida

Parameter Name
Drinking
Water
MCL1
Advanced Wastewater Treatment
Various
Counties
Florida
Utility
Council"
Brevard County
South
Beaches
WWTP'
Cape Canaveral WWTP
Sample Dale
10/1 /991
Sample Date
4/3/01'
Reclaimed Water Treatment
Various
Conn lies
Florida
Utility
Council2
Pinellas
County
Albert Whined
WRF, St.
Petersburg6
Secondary
Effluent
Various
Counties
Florida
Utility
Council'
Dade
County
Miami-Dade
Norm District7
Native Water Monitoring Zones
Florida Utility Council2 - Various Counties
Effluent
Injection
Zone
Lower
Monitoring
Zone
Upper
Monitoring
Zone
ASR
Injection
Zone
Biscay ne
Monitoring
Zone
Inorganic Analysis
Arsenic (mg/L)
Barium (nig/L)
Cadmium (mg/L)
Chromium {mg/L)
Cvanide (mg/L)
Fluoride (nip/L)
Lead (ros/L)
Mercury (mg/L)
Nickel (tng/L)
Nitrate (mB/L)
Nilrile (mg/L)
Selenium (ms/L)
Sodium (mg/L)
Antimony (mg/L)
Beryllium (mg/L)
rhallium (mg/L)
0.050
2.000
0.005
0.100
0.200
4.000
A.L.=0.015
0.002
0.100
10.00
.000
0.050
160.0
0.006
0.004
3.002
0.001

0.000
nooi

0.940
0.000
0.000
0.002


0.001
64.00



< 0.0050
0.031
< O.OOiO
< 0.0050

0.080
< 0.0010
< 0.00020

9.6

< 0.0020
230



< 0.005

< 0.000 1
< 0.005


< 0.003
0.0004
< 0.03


< 0.005

0.011
< 0.004
< 0.002
< 0.0045
0.0070
< 0.00005
< 0.0009
< 0.006
0.505
0.0014
0.00021
0.0031
0.0620
< 0.0035
< 0.0026
121.0
0.0034
< 0.0001
< 0.0010
0.003
0.094
0.001
0.003
0.002
0.420
0.001
0.000
0.005
3.690
0.013
0.004
75.00
D.142
0.004
0.001
0. 003 14
<0.0103
<0.0022
<0.00625
<0.025800
0.73700
<0.0025S
<0.0002
<0.008
0.28000
0.18000
<0.00388
28.03500
0.002175
<0.000525
<0.0012
0.003
0.023
0.001
0.005
0.015
0.790
0.004
0.000
0.011
3.820
0.575
0.004
114.0
0.013
0.001
0.002
< 0.01
< 0.05
< 0.005
< 0.005
< 0.004
0.75
< 0.005
< 0.001
< 0.005
0.64
< 0.05
< 0.01
181
< 0.005
< 0.002
•c 0.002
0.010
0.184
0.004
0.014
0.006
0.700
0.069
0.000
0.023
0.420
0.009
0.637
S062
0.003
0.008
0.305
0.007
0.363
0.012
0.023
0.009
0.860
0.108
0.001
0.036
0.070
0.025
0.007
5514
0.019
0.010
0.013
0.005
0.089
0.065
0.006
0.004
1.470
0.022
0.001
0.025
0.040
0.012
0.004
1357
0.010
0.005
0.007
0.002
0.404
0.003
0.010
0.002
.580
0.002 •
0.000
0.004
0.030
0.006
0.005
1215
0.004
0.001
0.001
0.015
0.244
0.001
0.004
0.004
0.190
0.009
0.000
0.003
0.190
0.005
0.001
80.0
0.001
0.000
0.001
Secondary Analysis
Aluminum (mg/L)
Chloride (mg/L)
Copper (mg/L)
Iron (mg/L)
Manganese (mg/L)
Silver (mji/L)
Sulfate(mg/L)
Zinc (mg/L)
Color (PtCo units)
Color (APHA units)
Odor (TON)
PH
IDS (ma/L)
FSS (ma/L)
Foaming Agents (mg/L)
0.200
250.0
AL.=L3
0.300
0.050
0.100
250.0
5.000
15.00

3.000
6.5-8.5
500.0

1.500

S2.20
0.003
0.000


179.5
0.000








160
< 0.01
< 0.040
0.0058
< 0.010
110
0.037



7.42
1200

0.13


< 0.01


< 0.01

< 0.03





1.066*

0.0992
165
< 0.0005
0.0225
0.0185
0.0040
lit
0.0676
5

^
6.99
648
0.868 °

0.050
116.9
0.021
0.177
0.024
0.001
76.20
0.023
33.00

2.500
7.000
528.0

0.143
Oil 35
189
O.OOS6
0.0963333
0.012567
O.00392
41.7
0.036500
30

10
7.0775
5S7

0.305
0.074
151.85
0.004
0.183
0.018
0.002
56.623
0.014
43.91

10.95
6.863
550.71

2.518
< O.I
218
< 0.01
0.209
< 0.05
< 0.001
71.9
0.02

50
75
6.93
610


0.20
15302.5
0.21
3.151
0.038
0.037
2379.2
0.008
7.400

1.200
7.700
28682

0.080
0.917
9897.0
0.032
4.450
0.046
0.008
1117.9
0.015
6.300

3.300
7.900
18328

0.253
0.744
22033
0.132
19.294
0.027
0.005
401.0
0.059
12.60

2.100
7.700
412S

0.118
0.163
2448.4
0.010
1.079
0.043
0.004
521.8
0.082
12.00

1330
7.500
5240

0.074
0.823
176.2
0.005
0.420
0.013
0.003
38.80
0.025
2L90

0.700
8.100
533.0

0.193
rrihalomethane Analysis
Bromodichloromethane (ns/L)
Dibromochlorom ethane (ns/L)
rribromornelhane (Bromofomu ug/L)
Trichloromethane (Chloroform; ug/L)
Total THMs (jig/L)




80.00









230
6.4
40.9
122
1.2

10.200
10.700
< 0.31000
3.6900
24.600




26.850




6.7




61.584
< 0.5
< 0.5
< 0.5
7.18
7.18




0.167




0.650




0.500




2.607




0.026

-------
Appendix Table 1-1.  Drinking Water Standards and Sampling Results for Treated Wastewater and Native Water in South Florida

'arameier Name


Drinking
Wafer
MCL'
Advanced Wastewater Treatment
Various
Counties
Florida
Utility
Council"
Brevard County
South
Beaches
WWTF3
Cape Canaveral WWTP
Sample Date
10/I/994
Sample Date
4/3/0 1s
Reclaimed Water Treatment
Various
Counties
Florida
Utility
Council
Pinetias
County
Albert Whitted
WRF. St.
Petersburg6
Secondary
Effluent
Various
Counties
Florida
Utility
r- -|2
Council
Bade
County
Miami-Dade
North District'
Native Water Monitoring Zones
Florida Utility Council - Various Counties
Effluent
Injection
Zone
Lower
Monitoring
Zone
Upper
Monitoring
Zone
ASR
Injection
Zone
Biscay ne
Monitoring
Zone
Radiological Analysis
Gross Alpha (pCi/L)
Gross Alpha excl, radon & uranium (pCi/L)
Radium-226 (pCi/L)
Radium-228 (pCi/L)
Radium-226 and Radium-228
15










< 4.0+/-2.3


0.5+/-0.1





< 1.60

< 0.30
< 0.90

3.167




<6.775+/-1.4

0.4+/-0.15
<0.75 +/-0.45

0.400




< 1+/-0.5




9.675




7.300




4.100




14.660




5.550




Microbiological Analysis
Total Coliform {col/ 100ml)
Fecal Colifonn (cfu/lOOml)
, or 5%*
0












-------
Appendix Table 1-1.  Drinking Water Standards and Sampling Results for Treated Wastewater and Native Water in South Florida

Parameter Name
ArochloM260(ng/L)
Toxaphene (HR/L)
Chlordane (ng/L)
Simazine (ua/L)
Atrazine (ug/L)
Oalapon (ng/L)
2.4-DOiR/L)
Pentachlorophenol (np/L)
Phenols (total: |ig/L)
2,4,5-TP (silyex; ug/L)
Pinoseb (iig/L)
Picloram (|tg/L)
Vinyl Chloride(^g/L)
].I-Dichloroethene(u£/L)
Methylene Chloride (ns/L)
Trans-1 ,2-Dichloroethene (MS/L)
Cis-U-Dichloroethene (up/L)
l,l,l-Trichloroethane(jig/L)
Carbon Tetrachloride (uo/L)
Benzene (ng/L)
1 -2-Dichloroethane (jiR/L)
rrichloroethene (fig/L)
].2-Dich!oropropane (ns/L)
Toluene (jig/L)
LIJ2-Trichloroethane(ng/L)
retrachloroetliene (ng/L)
Chlorobenzene (us/L)
Elhyl benzene (M£/L)
m & p-Xylene (HR/L)
O-Xylene (ug/L)
Xylenes (total; ng/L)
5tyrene(uB/L)
1 ,4-Di chlorobenzene (para) (jig/L)
l^-Di chlorobenzene (ortho) (iig/L)
I.2,4-Trichlorobenzene(|ig/L)
Di(2-Ethylhexyl)phthalate (ng/L)
Di(2-Elhylhexvl)adipate (|4g/L)
Benzo(a)pvTene (us/L)
Carbofuran (MS/L)
Oxamyl (vydate; lifJL}
Glyphosate (jig/L)
Bndothall (us/L)
Drinking
Water
MCL1

3
•>
4
3
200
70
1

50
7
500
2
7

100
70
200
5
5
5
5
5
1000
5
5
100
700


10000
100
75
600
70
6
400
0.2
40
200
700
100
Advanced Waslewater Treatment
Various
Counties
Florida
Utility
Council"










































Brevard County
South
Beaches
WWTF?

< 0.57




< 0.1


< 0.2


< 1




<
<
<
<
<



•c I






< 1









Cape Canaveral WWTP
Sample Date
IO/1/99*1
< 1.0
< 1.0
< 0.05




< 50




< 10
< 5
<• 5
< 5

< 5
< 5
< 5
< 5
< 5
< 5
< 5
< 5
< 5
< 5
e 5




< 5
< 5
< 10
< 10

< 10




Sample Date
4/3/0 r

< 0.500
< 0.500
< 0.176
< 0625
< 0.802
< 0.362
< 0.0545

< 0.0250
< 0 125
< 0.250
e 0.29000
< 0.02000
< 0.3)000
< 0.12000
< 0.03000
< 0.21000
< 0.2WOO
< 0.05000
< 0.02000
< 0.02000
< 0.33000
< 0.41000
< 0.23000
< 0.21000
< 0.23000
< 0.47000


< 0.24000
< 0.47000
< 0.02000
< 0.05000
< 0.22000
< 1.32
< 0.600
< 0.0400
< 0.900
< 1 13
< 2.4
< 3.00
Reclaimed Water Treatment
Various
Counties
Florida
Utility
Council2










































Pinellas
County
Albeit Whined
WRF. St.
Petersburg

<1.77
<0.64
<2.67
<1.4

-------
      Appendix Table 1-1.   Drinking Water Standards and Sampling Results for Treated Wastewater and Native Water in South Florida

Parameter Name
3iquat (J.LS/L)
^araquat (ug/L)
1,1-dichloroethane (us/L)
PCB-1242(mg/L)
PCB- 1254 (mg/L)
PCB-1221 (mg/L)
PCB-1232(ms/L>
PCB-1248(mg/L)
PCB-1260(rng/L)
PCB-10l6(mg/L)
Polvchlorinated byphenyls f PCBs; mg/L)
2,3,7.8-TCDD (Dioxin; mg/L)
Dichlorom ethane (mg/L)


Drinking
Water
MCL'
20









0.0005
3x1 0'3
0.005
Advanced Wastewater Treatment
Various
Counties
Florida
Utility
Council2













Brevard County
South
Beaches
WWTF3


< 1










Cape Canaveral WWTP
Sample Date
10/1/994


< 5










Sample Date
4/3/0 1 '
< 4.00

< 0.10000







< 0.250 mg/L


Reclaimed Water Treatment
Various
Counties
Florida
Utility
Council













Pinellas
County
Albert Whitted
WRF, St.
Petersburg
<0.4


<0.00075
<0.00075
O.00125
<0.00075
<0.00075
O.00075
<0.00075
<0.00023

<0.000625
Secondary
Effluent
Various
Counties
Florida
Utility
Council













Dade
Count)'
Miami -Dade
North District7
< 0.5
< I











Native Water Monitoring Zones
Florida Utility Council - Various Counties
Effluent
Injection
Zone













Lower
Monitoring
Zone













Upper
Monitoring
Zone













ASR
Injection
Zone













Biscay ne
Monitoring
Zone













      1 National Primary Drinking Water Regulations, 40 CFR 141 et seq.
      2 Engiehardt et. al. 2001. Comparative Assessment of Human and Ecological Impacts from Municipal Wastewater Disposal Methods in Southeast Florida, Table 2. Numbers are the average of the means of the measurements calculated with non-detects as zero
3>   and non-detects at their detection limit values.
|—'   3 South Beaches Wastewaler Treatment Facility, Melbourne Beach. FL. 2001.  Reciaimed Water or Effluent Analysis Report, Report Period 1/1/2000- 12/31/2000.  If monitoring result below the detection limit, this was indicated by showing a less than (<)
\JQ   sign preceding the detection limit.
      4 Florida Department of Environmental Protection.  1999. Annual Reclamed Water/Effluent Analysis for Primary and Secondary Drinking Water Standards, Cape Canaveral Wastewater Treatment Plant. Samples collected October 1.1999.  Laboratory Order
      Number B9-10-019.
      5 City of Cape Canaveral. 2001.  Laboratory Order Number 11926.
      6 City of St. Petersburg. Public Utilities Department, Albeit Whitted Water Reclamation Facility. Values are the average of sampling results from 9/98, 1/99,4/99,9/00, and 1/01, except values for ammonia, total nitrogen, total Kjeldah I nitrogen,
      orthophosphate, and water temperature, which are actual values measured 11/9/00.  Values that were non-detects with a detection limit greater than the MCL were excluded from the calculation of the averages. A "less than" sign preceding a value indicates that
      at least one of the annual sampling results was below the detection limit. It does not necessarily indicate that all annual sampling results were below the detection limit for any given constituent
      7 Miami Dade Water/Sewer. North District.  1999. Submission #9903001041, pp.  47-52. Screen effluent collected 3/19/99.  Monitoring results below detection limits are indicated by showing a less than (<) sign preceding the
      reported detection limit.
      8 For systems that collect >40 samples per month. MCL is 5% monthly samples are positive: for systems that collect <40 samples per month. MCL is 1 positive sample.

      9 Annual Average calculated from monthly averages in 1999 and 2001 supplied by  Florida Department of Environmental Protection (Cape Canaveral NPDES constituent data).  Data from May and June 2001  are unavailable; therefore, annual averages for 2001
      are calculated from 10 monthly averages.

-------
OT-TV
                                 Arithmetic Average


-------
Appendix Table 1-2.  Summary of Treated Wastewater Effluent Characteristics - SEFLOE data1 Continued
Broward
Parameter
Dichlorohroinomethane (u,g/L)
Chlorofonn (jig/L)
1,1,1 Tridiloroethane ((.ig/L)
Arsenic Total (fig/L)
Cadmium Total (ug/L)
Chromium Total (pg/L)
Copper Total (ug/L)
Lead Total (ug/L)
Nickel total (fig/L)
Selenium Total (ug/L)
Silver Total (fig/L)
Zinc Total ((.ig/L)
2/13/1991 9/20/1991
a/a
1.7
1.5
0.0
0.0
2.8
2.1
0.0
4.2
0.0
0.0
20.0
n/a
0.0
0.0
124.0
8.3
3.3
20.0
5.0
44.0
23.3
0.5
52.5
2/11/1992 3/24/1992 average average -qiies points
0
2.72
2.68
1.7
0 0.3
3.2
111.3
4.8
6.8
1
0.9
. Ill
1.23
2.18
0
2.3

179
14.4
6.7
6.7
2
0.5
34
0.615
1.65
1.0525
32
2.15
47.075
36.95
4.125
15.425
6.575
0.475
54.375
0.615
1.65
1.0525
1.333333333
2.15
47.075
12.16666667
4.125
15.425
6.575
0.475
• • 35.5
Hollywood


Parameter
Chloroform (fig/L)
Silver, Total (fig/L)
Zinc, Total (ug/L)
Phenols, Total (ug/L)

sampling
point
(11/25/91)
10
10 (ques)
15
70
Dade-North
Parameter
Chloroform ((.ig/L)
Ethylbenzene (ng/L)
Toluene (ug/L)
Heptachlor (ug/L)
Antimony Total (ug/L)
Arsenic Total (fig/L)
Cadmium Total (ug/L)
Copper Total (fig/L)
Lead Total (ug/L)
Nickel total (ug/L)
Selenium Total (j^g/L)
Thallium Total (ug/L)
ave - ques
2/27/1991 2/18/1992 average points
10.01
0.5
2.14
0,183
26.3
0.83
3.0
19.0
20.2
5
0.91
38.9
8.0
0
0
0
0
0
0
16.0
0
0
0
0
9.005
0.25
1.07
00915
13.15
0.415
1.5
17.5
10.1
2.5
0.455
19.45
9.005
0.25
1.07
0
13.15
0.415
1.5
17.5
10.1
2.5
0.455
19.45
Dade-Central
Parameter
Tetrachloroethylene (ug/L)
Antimony Total (ug/L)
Cadmium Total (j.ig/L)
Copper Total (ug/L)
Lead Total (ug/L)
Nickel total (ug/L)
Silver, Total (fig/L)
Thallium Total (jig/L)
Zinc Total (ug/L)
Cyanide Total (ug/L)
Phenols, Total (ug/L)

2/22/1991
0
44.8
9
35
40
5
14
13
82
9.6


ave
- ques
9/20/1991 average points
6
0
0
10
0
0
0
0
0
0
11
3
22.4
4.5
22.5
20
2.5
7
6.5
41
4.8
11
3
22.4
4.5
22.5
20
2.5
0
6.5
41
4.8
11

-------
Appendix Table 1-3. Microbial Standards and Concentrations in Treated Wastewater.




Microbial Standards
Microbial Pathogens
and
Sewage Indicators

Total Coiiform (col/lOOml)
Fecal Coiiform (cfu/lOOml)
Enterovirus (mpn/100 L)
Enterovirus (PFU/100 L)2a
Enterovirus (PFU/100 L)2b
Cryptosporidium (oocysts/100 L)
Giardia lamblia (cysts/100 L)
Enterococci (cfu/100 mL)
Clostridium perfringens (cfu/100 mL)
Coliphages (pfu/100 mL)
Enterovirus (PFU/100L)
Coliphages Host E. coli (pFamp) (PFU/100 mL)
Coliphages Host E. coli C (PFU/100 mL)

Drinking
Water
Maximum
Containment
Level1
I,or5%
0












Florida Department
of Environmental
Protection
Recommended
Limits2
Average



0.044
14
5.8
1.4







Maximum



0.165
50
22
5







Summary of Requirements For
Disinfection Used in South Florida
Basic
disinfection

<200



5








Intermediate
disinfection

<14



5








High-Level
disinfection

BDL



5








    BLD = Below Detection Limit

-------
Microbial Surface Water Concentrations (1)
Microbial Pathogens and
Sewase Indicators

Total Coliform (col/lOOml)
Fecal Coliform (cfu/lOOml)
Enterovirus (mpn/100 L)
Cryptosporidium (oocysts/100 L)
Giardia lamblia (cysts/ 100 L)
Enterococci (cfu/100 mL)
Clostridium perfringens (cfu/100 mL)
Coliphages (pfu/100 mL)
Enterovirus (PFU/100L)
Coliphages Host E. coli (pFamp) (PFU/100 mL)
Coliphages Host E. coli C (PFU/100 mL)
Surface Water
Sarasota County
5 Streams in the
vicinity of Sarasota1
Average



6.6
ND






Range



ND-157
ND






Sarasota Bay !
Average



ND
ND






Range



ND
ND






Phillippi Creek1
Average



3.1
0.42






Range



ND-11
ND-2.9






Hillsborough
County
Tampa Bypass
Canal*
Average



3.1
0.42






Range



ND-11
ND-2.9






   - Nondetect

-------
Microbial Surface Waters Concentrations (2)
Microbial Pathogens and Sewage Indicators

Total Coliform (coi/lOOml)
Fecal Coliform (cfu/lOOml)
Enterovirus (mpn/100 L)
Cryptosporidium (oocysts/100 L)
Giardia lamblia (cysts/ 100 L)
Enterococci (cfu/100 mL)
Clostridium perfringens (cfu/100 mL)
Coliphages (pfu/100 mL)
Enterovirus (PFU/100L)
Coliphages Host E. coli (pFamp) (PFU/100 mL)
Coliphages Host E. coli C (pfu/100 mL)


Surface Waters
Brevard County
'j
Duda Ditches
single sampling date

100.9












-------
Microbia! Concentrations in Untreated and Treated Wastewater (1)
Microbial
Pathogens and
Sewaee Indicators

Total Coliform
(co!/100ml)
Fecal Coliform
(cfu/lOOml)
Enterovirus
(mpn/lOOL)
Cryptosporidium
(oocysts/lOOL)
Giardia lamblia
(cysts/ 100 L)
Enterococci
(cfu/lOOmL)
Clostridium
perfringens
(cfu/tOO mL)
Coliphages (pfu/100
mL)
Enterovirus
(PFU/100L)
Coliphages Host E.
coli (pFamp)
(PFU/lOOmL)
Coliphages Host E.
coliC (pfu/100 mL)
Raw
Wastewater
United States
Urban
Communities
within the
United States'
sampling dates
unknown
22x(106)
8x(106)









Secondary
Treated
Wastewater
Dade County
MDWSD
North District
IW32
sampling date
3/19/99
0.0005










Secondary Treated Wastewater
Broward County
City of Fort
Lauderdale
sampling
date
4/25/96
2100










City of
Hollywood3
sampling
date
4/25/96
0.5










Sunrise
(IW1
and
IW2)3
sampling
date
2/11/00
280










Sunrise
(IW3)3
Sawgrass
sampling
date
unknown
180










Hollywood
WTP
(reuse
filter)3
sampling
date 7/9/99
0.5










Broward County
Regional WWTP
(Reuse Composite
Sampler)4
average of 30
values taken in
September 2001
0.033
0










-------
Microbial Concentrations in Treated Wastewater (2)
Microbial Pa those us and
Sewage Indicators

Total Coliform (col/lOOml)
Fecal Coliform (cfu/lOOml)
Enterovirus (mpn/100 L)
Cryptosporidium (oocysts/100
L)
Giardia lamblia (cysts/100 L)
Enterococci (cfu/100 mL)
Clostridium perfringens
(cfu/100 mL)
Coliphages (pfu/100 mL)
Enterovirus (PFU/100L)
Coliphages Host E. coli (pFamp)
(PFU/lOOmL)
Coliphages Host E. coli C
(pfu/lOOmL)
Secondary Effluent
Brevard County5
BCUD/ South
Central Regional
WWTF6
daily sample
results
(mon siteEFA-1;
avg of monthly)

0.03









South Beaches
WWTF7
daily sample
results
(mon site EFA-
1 ; avg of
monthly)

0.04









BCUD/Port St.
John WWTF
daily sample
results
(mon site EFA-
1; avg of
monthly)

0.18









Barefoot Bay
Advanced
Wastewater
Treatment Facility
daily sample
results-ROOl reuse
irrigation
(mon siteEFA-1;
avg)

0









BCUD/ Sykes Creek
Regional WWTF
daily sample results-
reuse
(mon site EFA-2;
avg)

0










-------
Microbial Concentrations in Treated Wastewater (3)
Microbial Pathogens and
Sewage Indicators
Total Coliform (coI/lOOml)
Fecal Coliform (cfu/lOOml)
Enterovirus (mpn/100 L)
Cryptosporidium (oocysts/100
L)
Giardia lamblia (cysts/ 100 L)
Enterococci (cfu/1 00 mL)
Clostridium perfringens
(cfu/100 mL)
Coliphages (pfu/100 mL)
Enterovirus (PFU/100L)
Coliphages Host E. coli (pFamp)
(PFU/lOOmL)
Coliphages Host E. coli C
(pfuAOOmL)
Reclaimed Water
Finellas County
Albert Whitted
WRF,
o
St. Petersburg
Sampling date
11/28/00



1.85
0.26






St. Petersburg9
Average



0.75
0.49



0.01


Maximum



5.35
3.3



0.133


Advanced Wastewater Treatment
Brevard County
Cape Canaveral WWTP
NPDES database
Annual
average
1999T°

0.125









Annual
average
200 lTi

1.15









Hillsborough County
Howard Curren WWTP12
Sample
date
5/5/00



<0.7
<0.7






Sample date
5/16/01



2.33
<0.29







-------
       Microbial Concentrations in Monitoring Wells (1)
Microbial Pathogens and
Sewage Indicators
Total Coliform (col/lOOml)
Fecal Coliform (cfu/lOOml)
Enterovirus (mpn/100 L)
Cryptosporidium (oocysts/100 L)
Giardia lamblia (cysts/100 L)
Enterococci (cfu/100 mL)
Clostridium perfringens
(cfu/lOOmL)
Coliphages (pfu/100 mL)
Enterovirus (PFU/iOOL)
Coliphages Host E. coli (pFamp)
(PFU/lOOmL)
Coliphages Host E. coli C
(pfu/100 mL)
Deep Injection Monitoring Wells
Pinellas County
Well ID
AWWRF 7571
Average of the results
from 20 sampling
events between 4/98
and 12/00


<1.0








Well ID
AWWRF 7581
Average of the results
from 20 sampling
events between 4/98
and 12/00


<1.0








Well ID
AWWRF 7791
Average of the results
from 20 sampling
events between 4/98
and 12/00


<1.0








St Petersburg1
Sampling date
10/13/002
<0.058
<0.058
<0.1
<0.17
<0.17
<0.058
<0.058


<5
<5
oo

-------
Microbial Concentrations in Ground Water Monitoring Wells (2)
Microbial Pathogens and
Sewage Indicators

Total Coliform (col/1 00ml)
Fecal Coliform (cfu/lOOml)
Enterovirus (mpn/100 L)
Cryptosporidium (oocysts/100 L)
Giardia lamblia (cysts/ 100 L)
Enterococci (cfu/100 mL)
Clostridium perfringens
(cfu/100 mL)
Coliphages (pfu/100 mL)
Enterovirus (PFU/100L)
Coliphages Host E. coli (pFamp)
(PFU/lOOmL)
Coliphages Host E. coli C
(pfu/lOOmL)
Deep Injection Monitoring Wells
Various Counties
Native Water Monitoring Zones
Effluent
Injection Zone
33.50










Lower
Monitoring Zone
7.00










Upper
Monitoring Zone
0.500










ASR Injection
Zone
6.00










Biscayne
Monitoring Zone




•







-------
Microbial Concentrations in Ground Water Monitoring Wells (3)
Microbial Pathogens and
Sewage Indicators
Total Coliform (col/lOOml)
Fecal Coliform (cfu/lOOml)
Enterovirus (mpn/100 L)
Cryptosporidium (oocysts/100 L)
Giardia lamblia (cysts/100 L)
Enterococci (cfu/100 mL)
Clostridium perfringens
(cfu/lOOmL)
Coliphages (pfu/100 mL)
Enterovirus (PFU/100L)
Coliphages Host E. coli (pFamp)
(PFU/lOOmL)
Coliphages Host E. coli C
(pfu/lOOmL)
Deep Injection Monitoring Wells
Pinellas County
AWWRF well
7792
Sample date
12/1/99
<0.058
<0.058
<0.071
1.18
<0.29
<0.058
<0.058
<5



SWWRF well
7652
Sample date
12/1/99
<0.058
<0.058
<0.060
<0.30
<0.30
<0.058
<0.058
<5



SWWRF well
7682
Sample date
12/1/99
<0.058
<0.058
<0.075
0.74
<0.15
<0.058
<0.058
<5



NWWRF well
7982
Sample date
12/1/99
<0.058
<0.058
<0.05
0.36
O.30
<0.058
<0.058
<5



AWWRF well
7582
Sample date
12/1/99
O.058
<0.058
0.074
0.14
<0.14
O.058
<0.058
<5



NEWRF well
7842
Sample date
12/1/99
<0.058
<0.058
<0.080
<0.11
<0.11
<0.058
<0.058
<5




-------
FOOTNOTES TO APPENDIX 1-3 (MICROBIAL PATHOGEN TABLE).

Footnotes for Table - Microbial Standards

    1   Maximum Contaminant Level (MCL). National Primary Drinking Water
       Regulations, 40 CFR 141 et seq.

   2   York,D.W.,P. Menendez, and L. Walker-Coleman.  2002.  Pathogens in
       Reclaimed Water: the Florida Experience. 2002 Water Sources Conference.
       2a.    Assumes all Enterovirus is highly infective Rotavirus.
       2b.    Assumes all Enterovirus is moderately infective Echovirus.
Footnotes for Table - Microbial Concentrations in Treated Effluent

   1  Geldriech, E.E. 1978 in Wood, I.R. et al. 1993. Ocean Disposal of Wastewater.
      Advanced Series on Ocean Engineering. Volume 8. World Scientific Publishing
      Co. Pte. Ltd.  Samples taken from several urban communities in the United States.

   2  Englehardt al. 2001. Comparative Assessment of Human and Ecological Impacts
      from Municipal Wastewater Disposal Methods in Southeast Florida. Florida
      Water and Environment Utility Council.

   3  Englehardt al. 2001. Comparative Assessment of Human and Ecological Impacts
      from Municipal Wastewater Disposal Methods in Southeast Florida. Florida
      Water and Environment Utility Council.

   4  Broward County  Office of Environmental Services, Environmental Operations
      Division, Compliance and Monitoring Section. Facsimile. Contact: Richard
      Walker.

   5  Florida Department of Environmental Protection Discharge Monitoring Reports
      for Brevard County.

   6  Florida Department of Environmental Protection Discharge Monitoring Reports
      for Brevard County. No detection limit was given; zero was used in calculations
      where non-detect (ND) was entered on data form. Values are averages from
      monthly reported values for March, April, and May 2001, except for "created
      wetlands" value, which is the average of March and April reported values (no
      discharge to wetlands in May 2001) and for "surface water" value.

   7  Florida Department of Environmental Protection Discharge Monitoring Reports
      for Brevard County. Values are averages from monthly reported values for
      March, April, and May 2001, calculated by Horsley & Witten, Inc. No detection
      limit was given; zero was used in calculations where non-detect (ND) was entered
      on data form.
                                    Al-21

-------
   8   Sampling results provided by Mr. Alfredo Crafa, Environmental Compliance
       Division, Albert Whitted Wastewater Reclamation Facility, March 18, 2002, City
       of St. Petersburg, Florida.

   9   York, D.W., P. Menendez, and L. Walker-Coleman.  2002. Pathogens in
       Reclaimed Water: the Florida Experience.  2002 Water Sources Conference.

   10  Annual average calculated from monthly averages in 1999 supplied by Florida
       Department of Environmental Protection (Cape Canaveral National Pollution
       Discharge Elimination System constituent data). Data from May, June,
       November, and December are unavailable; therefore, coliforms per 100 mL
       annual averages for 1999 are calculated from 8 monthly averages.  Seven of eight
       months reported 0 fecal coliforms; one month detected <1 fecal rk.  Personal
       Communication (February 22, 2002).  Results are for pathogens in reclaimed
       wastewater intended for reuse.

   11  Annual average calculated from twelve monthly averages in 2001 supplied by
       Florida Department of Environmental Protection (Cape Canaveral NPDES
       constituent data).  Eleven months reported <1 cfu/100 mL; one month (January)
       reported 2.8 cfu/100 mL.

   12  David York, Ph.D., P.E., Reuse Coordinator, Florida Department of
       Environmental Protection, personal communication (February 22, 2002). Results
       are the pathogens in reuse effluent from the Howard Curran Wastewater
       Treatment Plant.
Footnotes for Table - Microbial Data from Monitoring Wells

    1   The Albert Whitted Wastewater Reclamation Facility provided sampling data for
       microbes from effluent treated to Advanced treatment standards. Values are the
       average of 20 sampling events for microbial concentrations in three (3)
       monitoring wells between the period of March 1998 and December 2000.

   2   Sampling results provided by Mr. Alfredo Crafa, Environmental Compliance
       Division, Albert Whitted Wastewater Reclamation Facility, March 18, 2002, City
       of St. Petersburg, Florida.

   3   Rose, J.B., and W. Quintero-Betancourt, J. Jarrel, E. Lipp, S. Farrah, G. Lukasik,
       and T. Scott. 2001. Deep Injection Monitoring Well: Water Quality Monitoring
       Report. Report to the Florida Department of Environmental Protection.
                                     Al-22

-------
Footnotes for Table - Microbial Data from Surface Waters

    1   Florida Department of Environmental Protection, Risk Impact Statement, Phase II
       Revisions to Chapter 62-610, F.A.C., Docket No. 95-08R.

    2   Average of samples taken on 3/13/01 at 10 surface water-sampling stations.
       Florida Department of Environmental Protection Discharge Monitoring Reports.

Footnotes for Table - Microbial Data from Ohio River in the Cincinnati, Ohio Area

    1   York, D.W., P. Menendez, and L. Walker-Coleman.  2002. Pathogens in
       Reclaimed Water: the Florida Experience. 2002 Water Sources Conference.
       Values are the average of five separate sampling events.

    2   York, D.W., P. Menendez, and L. Walker-Coleman.  2002. Pathogens in
       Reclaimed Water: the Florida Experience.  2002 Water Sources Conference.
       Values are the average of four separate sampling events.

    3   York, D.W., P. Menendez, and L. Walker-Coleman.  2002. Pathogens in
       Reclaimed Water: the Florida Experience. 2002 Water Sources Conference.
       Values are the average of two separate sampling events.

Footnotes for Table - SDWTP Monitoring Well Data, Dade County

    1   South District Wastewater Treatment Plant, Miami-Dade County, Florida.
       Monitoring Well Purging Report.
                                    Al-23

-------
Appendix 1-3.

1.0    General
Microbial Pathogens and Description of Data Sources
Appendix Table 1-3 provides data on microbial concentrations in treated effluent and
monitoring samples, collected from various sources. These sources include information
compiled from:

      •   The National Pollutant Discharge Elimination System (NPDES) effluent quality
         database for Cape Canaveral WWTP including years 1999-2001;
      •   David York (personal communication), regarding microbial concentrations in
         treated effluent at the Howard Curren WWTP in Hillsborough County;
      •   Several sets of microbial data from the Alfred Whitted AWT facility, including
         results for treated effluent and deep injection monitoring wells;
      •   A Florida Water Environment Association Utility Council (FWEAUC) report,
         including monitoring data from several groundwater monitoring zones and data
         from secondary-treated effluent from facilities in Broward and Dade counties;
      •   A report to the Florida Department of Environmental Protection authored by JB
         Rose, W. Quintero-Betancourt, J. Jarrel, E. Lipp, S. Farah, G. Lukasic, and T.
         Scott in 2001, which includes data for six deep injection monitoring well wells
         in St. Petersburg, Pinellas County;
      •   Florida Department of Environmental Protection Discharge Monitoring Reports
         for several waste water treatment facilities in Brevard County, including:
          o  BCUD/South Central Regional WWTF
          o  Barefoot Bay WWTF
          o  BCUD/Sykes Creek Regional WWTP
          o  BCUD/Port St. John WWTF
          o  South Beaches WWTF
      •   The Broward County Office of Environmental Services, which provided water
         quality data for reclaimed water (including total coliform and fecal coliform
         values) from the Broward County Regional Wastewater Treatment Plant for the
         month of September 2001;
      •   A report by D.W. York, P. Menendez, and L. Walker-Coleman entitled
         Pathogens in Reclaimed Water: The Florida Experience 2002, which includes
         a review of reclaimed water quality in St. Petersburg as reported by J.B. Rose
         and R. P. Carnahan; and
      •   A Risk Impact Statement prepared in 1998 by the Florida Department of
         Environmental Protection, which includes surface water monitoring data for
         microbes for Sarasota and Hillsborough Counties.

2.0    The National Pollutant Discharge Elimination System (NPDES)

National Pollutant Discharge Elimination System (NPDES) data for Cape Canaveral for
the years 1999-2001were obtained in spreadsheet format from the Florida Department of
Environmental Protection.  The average annual concentrations of fecal coliform bacteria
in treated effluent from this facility were calculated from monthly averages in 1999 and
                                     Al-24

-------
 2001. Data from May, June, November, and December 1999 were unavailable; therefore,
 the annual average number of fecal coliform colony forming units (cfu) per 100 mL was
 calculated from 8 monthly averages. Seven of eight months reported zero (0) fecal
 coliforms; one month detected fewer than 1 cfu per 100 mL of treated effluent. During
 2001, eleven of twelve monthly results were less than 1 cfu/100 mL; one month (January)
 reported 2.8 cfu/100 mL,

 3.0    Howard Curren WWTP

 David York, Ph.D., Reuse Coordinator for the Florida Department of Environmental
 Protection, provided results from two sampling events at the Howard Current Wastewater
 Treatment Plant.  These sampling events measured Giardia and Cryptosporidium in
.effluent treated to reuse standards. These  sampling events occurred on May 5, 2000, and
 on May 16,2001.

 4.0    Albert Whitted Water Reclamation Facility

 The Albert Whitted Wastewater Reclamation Facility provided sampling data for
 microbes from effluent treated to Advanced Treatment standards (sampling date
 November 28, 2000) as well as from three deep monitoring wells (sampling date October
 13, 2000).  The microbial results for the treated effluent sample were obtained from a
 single sample of 378.5  liters. The deep monitoring well results in the table reflect the
 data from each of the three wells as well as duplicate samples for each monitoring well;
 all microbial parameters were below detection limits (indicated by the "less than" (<)
 sign) in all the monitoring well samples.

 5.0    Florida Water  Environment Association Utility Council

 The Florida Water Environment Association Utility Council (FWEAUC) report
 (Englehardt et al., 2001) provided analysis of sampling and monitoring results of effluent
 that had been treated to different standards (advanced wastewater treatment, secondary
 treatment, and advanced secondary treatment) as well as "native" ambient water in
 injection zones and monitoring zones in target aquifers.  The data that presented in the
 "Native Water Monitoring Zones" columns in Table X.X represents "digested" data that
 have already been processed by the FWEAUC authors, who calculated the average
 concentrations of each parameter from several sampling locations and events. The
 "digested" data effectively assign a value of one-half the detection limit to non-detects, a
 standard approach not inconsistent with risk assessment methodologies (US EPA. 1998).

 The authors of the FWEAUC report also include raw concentration data for each of the
 sampling stations in appendices B and C of their report.  The concentration of total
 coliform bacteria for several wastewater treatment facilities in south Florida were
 obtained from these appendices and entered into Table X.X. Microbial data were only
 available for facilities treating to secondary treatment standards. Non-detects (for the
 City of Hollywood treated effluent and reuse filter) were assigned a value of one-half the
                                     Al-25

-------
detection limit of 1.0 cfu/100 mL (0.5 cfu/100 mL) in the table. Facilities for which total
coliform bacteria concentrations were available include:

     •   City of Hollywood (Broward County);
     •   City of Sunrise Sawgrass Facility (IW3; Broward County);
     •   City of Ft. Lauderdale (Broward County);
     •   Miami-Dade Water and Sewer Department North District (IW3; Dade County);
     •   City of Hollywood Reuse Filter (Broward County); and
     •   City of Sunrise (IW1 + IW2; Broward County).

St. Petersburg, Pin ell as County

A report to the Florida Department of Environmental Protection authored by JB Rose, W.
Quintero-Betancourt, J. Jarrel, E. Lipp, S. Farah, G. Lukasic, and T. Scott in 2001
includes monitoring data for six deep monitoring wells associated with Class I municipal
injection wells at four wastewater facilities in St. Petersburg: the Southwest Wastewater
Reclamation Facility (SWWRF), the Northwest Wastewater Reclamation Facility
(NWWRF), the Northeast Wastewater Reclamation Facility (NEWRF) and the Albert
Whitted Wastewater Reclamation Facility (AWWRF). Values entered into Table X.X
(monitoring wells) represent results from single sampling events at each monitoring well.

6.0    Florida Department of Environmental Protection Discharge Monitoring
       Reports

The Florida Department of Environmental Protection provided monthly Discharge
Monitoring Reports covering March, April, and May 2001, for several wastewater
treatment facilities in Brevard County.  Those facilities include:

     •   BCUD/South Central Regional WWTF
     •   Barefoot Bay WWTF
     •   BCUD/Sykes Creek Regional WWTP
     •   BCUD/Port St. John WWTF
     •   South Beaches WWTF

For each of the facilities daily monitoring data were provided for Fecal Coliform levels.
The values entered in Table XX (treated effluent) are the averages for March, April and
May that are then averaged together.

7.0    Broward County Office of Environmental Services

Richard Walker provided monitoring data, via facsimile, from the Broward County
Office of Envirnomental Services Analytical Laboratory, for the Broward County
Regional WWTP.  Daily monitoring data was supplied for the month of September 2001
for advanced secondary treated effluent. The sampling location was the Reuse
Composite Sampler.  Total  and Fecal Coliform levels were reported in counts/100 mL.
                                     A1-26

-------
The values in Table XX (treated effluent) are the average of the 30 values reported for
September 2001.

8.0    Pathogens in Reclaimed Water: The Florida Experience

The paper authored by David York, Ph.D., and Lauren Walker-Coleman of the Florida
Department of Environmental Protection and Pepe Menendez, P.E., of the Florida
Department of Health outlines Florida's addition of required monitoring for the
protozoan pathogens Cryptosporidium and Giardia in domestic wastewater, to the state's
regulations regarding water reuse. The paper contains summarized monitoring data
through September 2001 taken in Monterey County, California and St. Petersburg
Florida. The data provided in Table XX (treated effluent) represents the average of all
data collected through September 2001 and the maximum concentration of pathogens
found reclaimed water.  The paper also contains fecal and total coliform data from the
Ohio River in the Cincinnati, Ohio area.  These data were taken over a four month period
from September 8, 1975 through December 1, 1975. Three separate sampling stations
were monitored and the values in table XY (surface water) are the averages of the
combined sampling events at each separate station.

9.0    Risk Impact Statement, Florida Department of Environmental Protection

Surface water monitoring data for microbes for Sarasota and Hillsborough Counties were
taken from the Risk Impact Statement, Phase II Revisions prepared by the Florida
Department of Environmental Protection. The data provided in Table  XX represents the
average concentrations and the range of oocysts/lOOL of water of Giardia and
Cryptosporidium in reclaimed water in St. Petersburg and surface waters in Sarasota and
Hillsborough Counties.  The sampling dates for this study are unknown. The surface
waters samples collected in Sarasota County include 24 samples taken in five streams,
four samples taken from a high quality estuary within Sarasota Bay, and 16 samples
taken from Phillippi Creek, an urban stream within Sarasota. The samples collected in
Hillsborough County include seven samples taken from the Tampa Bypass Canal
                                     Al-27

-------
                                 References

Barefoot Bay Advanced Wastewater Treatment Facility, Brevard County Water
       Resources Department, Brevard County. Discharge Monitoring Report March 01,
       2001-March 31, 2001.

Barefoot Bay Advanced Wastewater Treatment Facility, Brevard County Water
       Resources Department, Brevard County. Discharge Monitoring Report April 01,
       2001-April 30, 2001.

Barefoot Bay Advanced Wastewater Treatment Facility, Brevard County Water
       Resources Department, Brevard County. Discharge Monitoring Report May 9,
       2001-May 31,2001.

BCUD/South Central Regional Wastewater Treatment Facility, Brevard County Water
       Resources Department, Brevard County. Discharge Monitoring Reports March
       01,2001-March 31,2001.

BCUD/South Central Regional Wastewater Treatment Facility, Brevard County Water
       Resources Department, Brevard County. Discharge Monitoring Reports April 01,
       2001-April 30, 2001.

BCUD/South Central Regional Wastewater Treatment Facility, Brevard County Water
       Resources Department, Brevard County. Discharge Monitoring Reports May 01,
       2001-May 31, 2001.

BCUD/Sykes Creek Regional Wastewater Treatment Plant, Brevard County Water
       Resources Department, Brevard County. Discharge Monitoring Reports March
       01, 2001-March 31, 2001.

BCUD/Sykes Creek Regional Wastewater Treatment Plant, Brevard County Water
       Resources Department, Brevard County. Discharge Monitoring Reports April 01,
       2001-April 30, 2001.

BCUD/Sykes Creek Regional Wastewater Treatment Plant, Brevard County Water
       Resources Department, Brevard County. Discharge Monitoring Reports May 01,
       2001-May 31, 2001.

BCUD/Port St. John Wastewater Treatment Facility, Brevard County Water Resources
       Department, Brevard County. Discharge Monitoring Reports March 01, 2001-
       March31,2001.

BCUD/Port St. John Wastewater Treatment Facility, Brevard County Water Resources
       Department, Brevard County. Discharge Monitoring Reports April 01, 2001-
       April30,2001.
                                    Al-28

-------
BCUD/Port St. John Wastewater Treatment Facility, Brevard County Water Resources
       Department, Brevard County.  Discharge Monitoring Reports May 01, 2001- May
       31,2001.

Broward County Office of Environmental Services, Analytical Laboratory. Reclaimed
       water data for September 2001. Contact Richard Walker.

Cape Canaveral National Pollutant Discharge Elimination System (NPDES) Monitoring
       Database 1999-2001. Permit Number FL0020541.

City of St. Petersburg, Environmental Compliance Division. Sampling data for October
       13, 2000 at the Albert Whitted Wastewater Treatment Facility. Contact Alfredo J.
       Crafa, Manager.

David York, Ph.D., P.E., Reuse Coordinator, Florida Department of Environmental
       Protection, 2600 Blair Stone Rd.- MS 3540 Tallahassee, Florida 32399-2400,
       phone: (850) 922-2034, fax: (850) 921-6385, email: david.vorkfgdep.state.fl.us

Englehardt al. 2001.  Comparative Assessment of Human and Ecological Impacts from
       Municipal Wastewater Disposal Methods in Southeast Florida. Florida Water and
       Environment Utility Council.

Geldriech, E.E. 1978 in Wood, I.R. et al. 1993. Ocean Disposal of Wastewater.
       Advanced Series on  Ocean Engineering. Volume 8. World Scientific Publishing
       Co. Pte. Ltd.

Rose, J.B., et al. Deep Injection Monitoring Well: Water Quality Report (2001).
       University of South Florida.

South Beaches Wastewater Treatment Facility, Brevard County Water Resources
       Department, Brevard County.  Discharge Monitoring Reports March 01, 2001 -
       March 31,2001.

South Beaches Wastewater Treatment Facility, Brevard County Water Resources
       Department, Brevard County. Discharge Monitoring Reports April 01, 2001 -
       April 30, 2001.

South Beaches Wastewater Treatment Facility, Brevard County Water Resources
       Department, Brevard County.  Discharge Monitoring Reports May 01, 2001 -
       May 31, 2001.

South District Wastewater Treatment Plant, Miami Dade Water and Sewer Department,
       Miami Dade County, Florida. Monitoring Well Purging Report (Report A.)
       December 26, 2002.
                                    Al-29

-------
Appendix Table 1-4. Fecal Coliform Concentrations in Secondary Treated
Wastewater Effluent, South Dade Wastewater Treatment Plant, Dade County.
Effluent1
Number of times sampled
and range of dates
44
5/7/91-5/4/93
Fecal co li form
colonies/100 mL
0
40,000
>400
9,200
800
72,000
152,000
180,000
4,000
80,000
190,000
150,000
260,000
490,000
430,000
300
300,000
160,000
80,000
50,000
280,000
170,000
18,000
24,000
580,000
17,000,000
150,000
0
20,000
80,000
50,000
30,000
30,000
510,000
50,000
50,000
21
10,000
50,000
160,000
Date(s) detected
5/7/91
5/14/91
5/21/91
5/28/91
6/4/91
6/18/91
6/25/91
8/6/91
8/13/91
8/20/91
8/27/91
9/17/91
9/24/91
10/1/91
10/16/90
10/22/91
10/29/91
11/5/91
11/13/91
11/19/91
11/26/91
12/3/91
12/10/91
12/17/91
12/26/91
1/2/92
1/14/92
1/21/91
1/28/92
2/4/92
2/13/92
2/18/92
2/25/92
3/3/92
3/10/92
3/17/92
3/2/93
3/9/93
3/16/93
3/30/93
                                  Al-30

-------
Effluent1
Number of times sampled
and range of dates
44
5/7/91 . 5/4/93 (cont.)
52
5/11/93-4/4/95
Fecal coliform
colonies/100 mL
10,000
32,000
160,000
124
18,000
29,000
12,000
7,000
4,800
55,000
52,000
16,000
152,000
19,400
13,800
58,000
61,000
39,000
21,000
31,000
6,000
6,600
26,000
22,000
2,650
17,400
32,500
5,000
235
12,000
900
40
48,000
140,000
3,000
210,000
36,000
310,000
760,000
74,000
4
2
Date(s) detected
4/6/93
4/13/93
4/20/93
4/27/93
5/4/93
5/11/93
5/18/93
5/25/93
6/3/93
6/8/93
6/15/93
6/21/93
6/29/93
7/8/93
7/13/93
7/20/93
7/27/93
8/5/93
8/9/93
8/18/93
8/25/93
9/1/93
9/8/93
9/14/93
9/21/93
9/28/93
10/5/93
10/13/93
10/19/93
10/28/93
11/2/93
11/9/93
11/16/93
11/30/93
12/7/93
12/21/93
12/28/93
1/6/94
1/11/94
1/18/94
1/10/95
1/31/95
Al-31

-------
Effluent1
Number of times sampled
and range of dates
52
5/11/93-4/4/95
49
4/18/95-2/4/97
Fecal coliform
colonies/100 mL
4
2
19,800
9,800
156
230,000
120,000
62
6
12,000
46,000
100,000
180,000
8
154,000
70,000
80,300
120,000
64,000
24,000
58,000
13,000
58,000
14,000
42,000
18,500
56,000
70,000
32,000
29,000
70,000
29,000
42,000
67,000
480,000
140,000
33,000
45,500
45,000
99,000
62,500
93,000
26,000
Date(s) detected
2/6/95
2/13/95
2/21/95
2/28/95
3/8/95
3/28/95
4/4/95
4/18/95
5/2/95
5/16/95
5/23/95
5/31/95
6/7/95
6/13/95
6/20/95
6/27/95
7/5/95
7/18/95
7/21/95
8/3/95
8/8/95
8/15/95
8/23/95
8/29/95
9/5/95
9/12/95
9/19/95
9/28/95
10/3/95
10/11/95
10/17/95
10/31/95
11/7/95
10/8/96
10/16/96
10/22/96
10/29/96
11/5/96
11/12/96
11/19/96
11/26/96
12/3/96
12/10/96
Al-32

-------
Effluent1
Number of times sampled
and range of dates
4/18/95-2/4/97
(cont.)
40
2/11/97-10/2/97
Fecal coliform
colonies/100 mL
128,000
680,000
780,000
130,000
61,000
780,000
705,000
50,000
38,000
22,500
38,000
38,000
670,000
92,300
53,000
25,500
23,500
21,500
30,000
150,000
140,000
90,000
42,000
142,000
72,500
25,600
37,000
42
21,500
176,000
24,000
36,000
64,000
16
12,200
415,000
380,000
715,000
665,000
2,300,000
2,400,000
9,000,000
400,000
Date(s) detected
12/17/96
12/24/96
12/31/96
1/7/97
1/14/97
1/21/97
1/28/97
2/4/97
2/11/97
2/18/97
2/25/97
3/4/97
3/11/97
3/18/97
3/25/97
4/2/97
4/8/97
4/15/97
4/22/97
4/29/97
5/13/97
5/20/97
5/27/97
6/3/97
6/10/97
6/17/97
6/24/97
7/1/97
7/8/97
7/15/97
7/22/97
8/5/97
8/12/97
8/19/97
8/26/97
7/28/98
8/4/98
8/11/98
8/25/98
9/1/98
9/8/98
9/15/98
9/29/98
Al-33

-------
Effluent1
Number of times sampled
and range of dates
2/11/97- 10/2/97 (cont.)
Fecal coliform
colonies/100 mL
2,400,000
9,000,000
400,000
3,100,000
7,050,000
7,050,000
1,090,000
Date(s) detected
9/8/98
9/15/98
9/29/98
10/6/98
10/14/98
10/20/98
10/28/98
1 Reference:  South District Wastewater Treatment Plant, Miami Dade Water and Sewer
Department, Miami Dade County, Florida. Monitoring Well Purging Report
(Report A) December 26, 2002.
                                      Al-34

-------
Appendix Table 1-5.  Fecal Coliform Concentrations From Monitoring Wells, South District Wastewater Treatment Plant,
Dade County
Monitoring well1
FA1-U
FA1-L
FA2-U
FA2-L
FA3-U
FA3-L
Zone 4
FA5-U
FA5-L
FA6-U
Depth (feet)
980-1 ,090
1,840-1,927
980-1 ,020
1 ,645-1 ,672
981-1,050
1,771-1,892
1,702-1,840
1,490-1,588
1,790-1,890
1 ,490-1 ,584
Number of times
sampled
230
227
208
213
183
184
151
95
121
99
Number of fecal coliforms
detections (>0)
7
3
6
1
5
2
1
1
1
1
Fecal coliforms,
colonies/100 mL
2
4
14
94
400
150
6
4
4
58
2
>2000
520
340
110
4
10
6
2
8
200
4
2
4
100
2
6
4
Date(s) detected
3/1/87
3/1/90
1/1/91
10/1/92
12/8/92
4/13/93
1/10/95
3/1/90
10/1/92
12/8/92
12/1/90
9/24/92
10/1/92
10/8/92
10/14/92
10/20/92
10/1/92
3/9/93
3/16/93
4/13/93
11/28/94
6/13/95
5/21/91
4/13/93
9/24/92
1/10/95
4/4/95
1/10/95

-------
Monitoring well1
FA6-L
FA7-U
FA7-L
FA8-U
FA 8-l_
FA9-U
FA9-L
FA10-U
FA 10-L
FA11-U
FA11-L
FA12-U
FA 12-L
FA13-U
FA13-L
FA14-U
FA15-U
FA 15-L
FA16-U
FA16-L
B21
Depth (feet)
1 ,790-1 ,890
1 ,488-1 ,580
1,805-1,872
1,490-1,575
1 ,790-1 ,890
1 ,490-1 ,587
1,790-1,880
1,490-1,592
1,790-1,890
1,490-1,588
1,790-1,890
1,495-1,597
1,790-1,890
1480-1,585
1,740-1,845
1 ,490-1 ,575
1,490-1,575
1,790-1,890
1 ,490-1 ,590
1 ,790-1 ,890
1,005-1,037
Number of times
sampled
101
105
116
103
103
94
84
67
84
42
75
87
78
89
81
87
83
79
89
80
190
Number of fecal
coliforms detections (>0)
0
1
0
1
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
33
Fecal coliforms
colonies/100 m L
N/A
18
N/A
2
N/A
14
2
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
40
16
13
50
14
116
362
62
Date(s) detected
N/A
4/4/95
N/A
6/13/95
N/A
6/13/95
6/13/95
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
11/1/90
12/1/90
1/1/91
3/31/92
4/7/92
4/21/92
5/5/92
5/12/92

-------
-J
Monitoring well1

BZ1(cont.)
BZ-2
Depth (feet)

1,005-1,037
1 ,577-1 ,664
Number of times
sampled

(cont)
97
Number of fecal
coliforms detections (>0)

33
0
Fecal coliforms
colonies/100 mL
86
22
106
14
212
2
2
6
4
2
2
30
400
130
500
88
208
54
530
20
200
24
400
192
496
N/A
Date(s) detected
5/20/92
5/26/92
6/9/92
6/16/92
6/23/92
6/30/92
7/7/92
7/14/92
7/21/92
8/11/92
8/18/92
9/24/92
10/1/92
10/8/92
10/14/92
10/20/92
10/27/92
11/3/92
11/10/92
11/17/92
1/8/93
3/9/93
3/16/93 :
3/30/93
4/6/93
N/A
       1 Reference: South District Wastewater Treatment Plant, Miami Dade Water and Sewer Department, Miami Dade County, Florida.
       Monitoring Well Purging Report (Report A) December 26, 2002.

-------
Appendix 1-6. Class 1 Facilities in South Florida.
                          FACILITY AND WELL DATA

Facility Active
Albert Whitted 2
MDW&S South District Regional 13
Seacoast Utilities 1
McKay Creek 2
South Cross Bayou 3
St. Petersburg NE 3
St. Petersburg NW " 2
St. Petersburg SW 3
Broward County - North District Regional 4
G.f. Lohmeyer 	 5
Margate 2
MDW&S North District Regional
Palm Beach County - Southern Regional 2
Plantation Regional (Broward County) 2
South Beaches 1
Sunrise 3
Sykes Creek (Merritt Island) 2
Belle Glade 1
Brentwood WWTP (Atlantic Utilities) __ _ 1
Coral Springs Improvement District 2
East Port (Charlotte) 2
East-Central Regional 6
Encon 1
Ft. Myers Beach 1
Ft. Pierce Utility Authority 1
Gasparilla Island 1
Immokalee
Manatee County SW - Subregional 1
Melbourne - Grant St. 1
Miramar WWTP 2
North Ft. Myers Utilities 1
North Port (Charlotte) T
Pahokee 1
Palm Bay (GDU-Port Malabar) 1
Palm Beach County System #9 1
Pembroke Pines 2
Port St. Lucie Westport
Punta Gorda
Rockledge 1
Royal Palm Beach 1
South Collier County 1
South Port St. Lucie 1
Stuart " 2
West Melbourne 1
West Port (Charlotte) 1
Injection Wells
Under
Inactive Construction Proposed
.
4 	 4
-
	 : — „_ .___' 	
.
2 2
__.___. ^ _.._.._
.
"- 	 " 	 — -— -
_
_
_
. _!-__„ - ..." ~ 1
i --•---_•
-
-
_
- - " 1
..._-_ _ ___2 " -
-
                                    Al-38

-------
 Appendix Table 1-6. Class I Facility Treatment and Flow Data
Perrr
Treat
Cap
Facility (MC
Permitted Injection
itted Rate (Well
ment Capacity)
acity
3D) (MGD)
WbertWHfttetl 12.40 24.00 Par 2 wells
WIDVW.S Soulh District Regional
SeacoastUlilttHss
15.9 'IW-1
17.5 IIW-2
16,9 HW-3
17.8 'IW-4
:10.1B IW-5
1 15.00 JIVU6
116.7 'IW-7
,15.0 'IW-8
16.9 JlW-9
17.5 ilW.10
17.2 IIWMI
17.2 JIW-12
16.1 HVV-13
14.9 ilW-14
14.9 'IW-15
114.9 i|W-16
14.9 :IW-17
(208) (Total 1-13)
: 15.00 IW-1
dcKay Creek 6.00 6.35 Per 2 wells
South Cross Bayou 24.50 10.20 Per 3 wells
St. Petersburg NE 13.00 27.00 Total 3 wells
St. Petersburg NW 20.00 16.00 Per2wells
St. Petersburg SW 20.00 9.00 Per 3 wells
Brward Cwimy - North Olstnct
leg ton a)
G.T. Lohmeyer
Margate
MDUVaS North District Regional
Palm Beach County - Southern
Regional
Plantation Regional (Broward
Counly)
South Beaches
Sunnse
Sykes Creek (Merritt Island)
15 Per 4 wells
18.7 IW-5, 6
18.3 IW-1 -4
18.7 IW-5
(67) (Pump Cap.)
8,15 IW-1
15 IW-2
18.70 Per2wells
15.00 Per 2 walls
15 IW-1,2
(24.00) (Pump cap.)
9.00
18.70 IW-1,2,3
8.2 well 1
8.1 Well 2
Total Well
Capacity
(MGD)
48.00
269.48
15.00
12.70
20.40
27.00
32.00
27.00
97.40
91.90
23.15
33.40
30.00
30.00
9,00
59.10
16,30
Injectate Characteristics/ Current
Treatement in Place
Activated sludge process with chlorinated effluent to a
reclaimed waler spray irrigation system and back-
up/wet weather disposal to wells.
Secondary treated domestic wastenater effluent
Secondary treated domestic vrastewater
Secondary treated municipal effluent from a Type 1
contact stabilization municipal sewage treatment plant
with filtered chlorinated effluent
Filtered and chlorinated effluent from a conventional
activated sludge municipal treatment plant.
Activated sludge process with chlorinated effluent to a
reclaimed water spray irrigation system and back-
up/wet weather disposal to wells.
Activated sludge process with chlorinated effluent to a
reclaimed water spray irrigation system and back-
up/wet weather disposal to wells.
Municipal effluent from a Type 1 activated sludge
plant with chlorinated effluent to a reclaimed water
spray irrigation system and backup disposal to welts.
Secondary treated domestic wastewater (effluent)
Secondary treatment
Secondary treated domestic wastewaier.
Secondary treated domestic vwstewater (effluent)
Secondary treated domestic wastewater
Secondary treated domestic wastewater.
Secondary treated domestic wastewater (effluent)
Secondary treated domestic vrastewater, may include
membrane softening concentrate during planned
Minimum to secondary treatment levels • no
hlorinalion is necessary.
Emergency Disposal Practice
Injection wells used for backupjwet-weather disposal.









bxcess wastewater from East WWIHdiscftarged to
Margate canal and excess from West VWVTP discharged
o One Mile canal.

3.5 MGD and 4=5 MGD diverted Id Palm' Beach County"'
System #3 arid #9, respectively. Remaining effluent will
ie disinfected and allowed to overflow to on-stte
tormwater detention ponds.

Existing percolation ponds for overflow(15 million
lallons storage). Ability to store water at Indian River
and South Patrick treatment plants. A last option is
discharging to the Indian River.


Yellow highlighted denotes facilities reviewed (or risk assessment
Source: Florida status reports -January 2002; Florida Discharge Monitoring Reports-February 2002
                                                                  Al-39

-------
 Appendix 1-6 - Class I Facility Treatment and Flow Data
Pern
TTM
Cap
Facility (M
Bella Glade
Brentwood WWTP (Atlantic
Utilities)
Coral Springs Improvement
District
East Port (Charlotte)
East-Central Reg tonal
Encon
Ft. Myers Beach
Permitted Injection
^ Rate (Wall Capacity)
•city
3D) (MOD)
10.20
3.41
IW-1
4.87 15 IW-2
I2.04 IW-1
7.66 IW-2
IW-1
15.3 15 IW-2
17.3 ilW-3
20.7 ilW-4
18.7 IIW-5
18.7 IIW-8
(98.00) !(PumpCap.)
18.00
7.92
Fl. Pierce Utility Authority 10.00 14,92
Gat par II la Island
mmokalee
Manatee County SW-
Subreg tonal
Melbourne- Grant St.
Miramar WWTP
North Ft. Myers Utilities
North Port (Charlotte)
Pahokee
Palm Bay (GDU-Port Malabar)
3alm Beach County System #9
3embroke Pines
0.81
2.50
15.00
14.92
18.50 par 2 wells
4.00
4.75
4.00
10.00
12,70
7.69 IW-1
15,27 IW-2
(7.69) (Pump Cap.)
Total Wall
Capacity
(MOD)
10.20
3.41
19.87
9.60
105.70
18.00
7.92
14.92
0.81
2.50
15.00
14.92
37.00
4.00
4. 75
4.00
10,00
12.70
22.96
Port St. Lucle Weslport
Punta Gorda
Rockledge
Royal Palm Beach
South Collier County
South Ron St. Lucle
Stuart
12.00 For 1 well
4.50
6.34
18.00
3.41
3.5 IW-1
10.00 IW-2
West Melbourne 2,50 4.60
Wast Port (Charlotte)
4.75
12.00
4.60
6,34
18.00
3,41
13.50
4.80
4.75
Injectate Characteristic*/ Current Tre*t*merit
In Place
Secondary treated domestic wastewater
Secondary treated domestic wastewater
Secondary treated domestic wastewaler
Domestic wastewater
Secondary treated domestic wastewater
Secondary treated domestic wastewater
Domestic wastewaler
Conventional activated sludge secondary domestic
wastenater plant with Influent screening, grit removal,
aeration, secondary clarification, chlorlnatton, and
dechlorlnatlon.
Back up disposal of secondary treated domestic
wastevwter folloiMng filtration and disinfection
Backup dlsp of secondary treated domestic effluent
Treated municipal effluent receiving min, of secondary
treatment
Pretreated domestic wastewater!
Secondary treated municipal effluent
Secondary treated domestic wastewater; following
filtration and disinfection
Secondary treated domestic wastewater
Secondary treated domestic wastewater
Secondary treated domestic wastewater
Concentrate rejected waters from low-pressure
membrane softening process generated from the
water treatment facility


Secondary treated domestic effluent
Secondary treated effluent
Secondary treated domestic waslewater
Secondary treated domestic effluent
Secondary treated domestic waslewater
Secondary treated domestic wastewater; IW-1
(emergency back-up well) will Inject polable water
once a month
Secondary treated effluent
Secondary treated domestic waslewater
Emergency Disposal Practice


IW-1 serves as Ine backup well when IW-2 is out of
service.
To existing on site spray irrigation system, onsite storage
pond and discharge to surface waters.
Treated, chlorinated effluent to remaining Injection wells
and an equalization basin with capacity of 8 million
gallons, and then to the Atlantic Ocean via drainage
system.
Chlorinated effluent to stabilization pond, overflow to
recharge lake to a tributary of the Loxahatehee River.
Sent to reclaimed water system, then percolation ponds
wHh injection usod for excess effluent disposal.
Surface water discharge lo Indian River Lagoon
Well Is a backup discharge mechanism lo golf course
Irrigation. There Is 2.13 million gallon onsite holding
pond.
If well Is out of service, flow directed to existing effluent
holding ponds.

Suface water discharge directed to Crane Creak and on
lo the Indian River.
Directed to plant's stormwater collection system, which
flows Into a drainage canal.
Wall Is back up for plant. Additional disposal Is lo onsite
storage pond.

Directed to onstte polishing ponds.
Directed to South Harris Ditch to Turkey Creek and on to
the Indian River.

IW-1 Is used for emergency disposal. If flows exceed
permitted amount, pan of flow will be diverted to existing
percolation pond.

Directed to existing affluent disposal ponds.
Directed to Indian River via 2934 feel of effluent pipeline.
onsite percolation ponds.


Additional emergency flow Is diverted lo outfall system
into the St. Lucle River.
Emergency ponds store 3.2 million gallons, additional
flow diverted to Crane Creek drainage canal.
Flow directed to 3 existing percolation ponds (capacity
6,3 MGD) and to onslle spray irrigation system.
Source: Florida status reports -January 2002; Florida Discharge Monitoring Reports-February 2002
                                                              Al-40

-------
Appendix 1-6. Injectate Characteristics for Class I Injection Wells.
Facility
Albert Whitted
MDW&S South District Regional
Seacoast Utilities
McKay Creek
South Cross Bayou
St. Petersburg NE
St. Petersburg NW
St. Petersburg SW
Broward County - North District Regional
G.T. Lohmeyer
Margate
MDW&S North District Regional
Palm Beach County - Southern Regional
Plantation Regional (Broward County)
South Beaches
Sunrise
Sykes Creek (Merritt Island)
Belle Glade
Brentwood WWTP (Atlantic Utilities)
Coral Springs Improvement District
East Port (Charlotte)
Injectate Characteristics/ Current Treatement
in Place
Activated sludge process with chlorinated effluent
to a reclaimed water spray irrigation system and
back-up/wet weather disposal to wells.
Secondary treated domestic wastewater effluent
Secondarily treated domestic wastewater
Secondary treated municipal effluent from a Type
1 contact stabilization municipal sewage
treatment plant with filtered chlorinated effluent.
Filtered and chlorinated effluent from a
conventional activated sludge municipal treatmen
plant.
Activated sludge process with chlorinated effluent
to a reclaimed water spray irrigation system and
back-up/wet weather disposal to wells.
Activated sludge process with chlorinated effluent
to a reclaimed water spray irrigation system and
oack-up/wet weather disposal to wells.
Municipal effluent from a Type 1 activated sludge
plant with chlorinated effluent to a reclaimed
water spray irrigation system and backup disposal
to wells.
Secondarily treated domestic wastewater
Secondary treatment
Secondary treated domestic wastewater.
Secondary treated domestic wastewater (effluent)
Secondarily treated domestic wastewater
Secondary treated domestic wastewater.
Secondarily treated domestic wastewater
effluent)
Secondary treated domestic wastewater, may
nclude membrane softening concentrate during
planned outages of Injection Well CW-1 .
Minimum to secondary treatment levels - no
chlorination is necessary.
Secondary treated domestic wastewater
Secondary treated domestic wastewater
Secondary treated domestic wastewater
Domestic wastewater
Emergency Disposal Practice
Injection wells used for backup/wet -weather
disposal.









Excess wastewater from East WWTP
discharged to Margate canal and excess
from West WWTP discharged to One Mile
canal.

3.5 MGD and 4.5 MGD diverted to Palm
Beach County System #3 and #9,
respectively. Remaining effluent will be
disinfected and allowed to overflow to on-
site stormwater detention ponds.

Existing percolation ponds for overflow (15
million gallons storage). Ability to store
water at Indian River and South Patrick
reatment plants. A last option is
discharging to the Indian River.




W-1 serves as the backup well when IW-2
s out of service.
To existing onsite spray irrigation system,
onsite storage pond and discharge to
surface waters.
                                         Al-41

-------
Appendix 1-6. Injectate Characteristics for Class I Injection Wells.
Facility
East-Central Regional
Encon
Ft. Myers Beach
Ft. Pierce Utility Authority
Gasparilla Island
Immokalee
Manatee County SW - Subreqional
Melbourne - Grant St,
Miramar WWTP
North Ft. Myers Utilities
North Port (Charlotte)
Pahokee
Palm Bay (GDU-Port Malabar)
Palm Beach County System #9
Pembroke Pines
Port St. Lucie Westport
Punta Gorda
Rockledqe
Royal Palm Beach
South Collier County
South Port St. Lucie
Stuart
West Melbourne
West Port (Charlotte)
Injectate Characteristics/ Current Treatement
in Place
Secondary treated domestic wastewater
Secondary treated domestic wastewater
Domestic wastewater
Conventional activated sludge secondary
domestic wastewater plant with influent
screening, grit removal, aeration, secondary
clarification, chlorination, and dechlorinalion.
Back up disposal of secondarily treated domestic
wastewater following filtration and disinfection
Backup disp of secondarily treated domestic
effluent
Treated municipal effluent receiving min. of
secondary treatment
Pretreated domestic wastewaters
Secondary treated municipal effluent
Secondary treated domestic wastewater;
following filtration and disinfection
Secondary treated domestic wastewater
Secondary treated domestic wastewater
Secondary treated domestic wastewater
Concentrate rejected waters from low-pressure
membrane softening process generated from the
water treatment facility


Secondary treated domestic effluent
Secondary treated effluent
Secondarily treated domestic wastewater
Secondarily treated domestic effluent
Secondary treated domestic wastewater
Secondary treated domestic wastewater; IW-1
(emergency back-up well) will inject potable water
once a month
Secondary treated effluent
Secondary treated domestic wastewater
Emergency Disposal Practice
Treated, chlorinated effluent to remaining
injection wells and an equalization basin
with capacity of 8 million gallons, and then
to the Atlantic Ocean via drainage system.
Chlorinated effluent to stabilization pond,
overflow to recharge lake to a tributary of
the Loxahatchee River.
Sent to reclaimed water system, then
percolation ponds with injection used for
excess effluent disposal.
Surface water discharge to Indian River
Lagoon
Well is a backup discharge mechanism to
golf course irrigation. There is 2.13 million
gallon onsite holding pond.
If well is out of service, flow directed to
existing effluent holding ponds.

Suface water discharge directed to Crane
Creek and on to the Indian River.
Directed to plant's stormwater collection
system, which flows into a drainage canal.
Well is back up for plant. Additional
disposal is to onsite storage pond.

Directed to onsite polishing ponds.
Directed to South Harris Ditch to Turkey
Creek and on to the Indian River.

IW-1 is used for emergency disposal. If
flows exceed permitted amount, part of flow
will be diverted to existing percolation pond,

Directed to existing effluent disposal ponds.
Directed to Indian River via 2934 feet of
effluent pipeline,
Surficial aquifer recharge through rapid rate
infiltration in onsite percolation ponds.


Additional emergency flow is diverted to
outfall system into the St. Lucie River.
Emergency ponds store 3.2 million gallons,
additional flow diverted to Crane Creek
drainage canal.
Now directed to '6 existing percolation
ponds (capacity 6.3 MGD) and to onsite
spray irrigation system.
                                         Al-42

-------
   Appendix Table 2-1 Dade County


1












2






3








4








S








6








7







Authors

Reese, R S.












Reese, R.S. and
Cunningham, K.J.






Maliva, R.G. and
VUilker, C W.








Meyer, F.W.








Reese, R.S. and
Memburg, S J.








Duerr, A.D.








Englehardt.J.Q.etal.







Title
Hydrogeotogy arid the Qstribution and the Origin of
Saliritymthe Floridan Aquifer System Southeastern
Florida











Hydrogeology of the Gray Limestone Aquifer in Southern
Florida






Hydrogeology of DeepAAtell Disposal of Uqiid V\&stesin
Southwestern Florida, USA







Hydrogeology, Ground-Water Movement, and Subsurface
Storage in the Floridan Aquifer System in Southern
Florida







Hydrogeology and the Distribution of Salinity in the
Roridan Aquifer System, Palm Beach County, Florida








Types of Secondary Porosity of Carbonate Rocks in
Injection and Test Wells in Southern Peninsular Florida







Comparative Assessment of Human and Ecological
Impacts from Municipal Wasteirater Dsposal Methods in
Southeast Ron da






Date

1994












1^fan-00






Aug-98








1989








1999








1995








23-Apr-Q1







Source

USGS W1 94-4010












USGS V\RI 99-421 3






Hydrogeology Journal








USGS Prof. Paper 1403-G








USGS VWI 99-4061








USGS V\RI 94-4013








University of Miami







Hydrogeologlc Unit

Surflclal Aquifer

Surficial Aquifer (Biscayne]
Intermediate Confining Unit
Floridan Aquifer System

Upper Floridan Aquifer
Suwannee
Ocala
Avon Park

Middle Confining Unit
Lower Floridan Aqutler
Surficlal Aquifer
Bscayne Aquifer
Upper Serriconfining to Confining
Unit
Gray Limestone Aquifer
Lower Semiconftring Unit
Sand Aqufers
Surficial Aquifer
Intermediate Confining Unit
Floridan Aquifer System
Upper Floridan Aquifer
Middle Confining Unit
lower Floridan Aquifer

Bolder Zone. 750 - 950 bis

Surficial Aquifer

Intermediate Confining Unit
Floridan Aquifer System
Upper Floridan Aquifer
Middle Confining Unit
Lower Floridan Aquifer

Bolder Zone
Surficlal Aquifer
Intermediate Confining Unit
Floridan Aquifer System

Upper Floridan Aquifer

Middle Confining Unit
Lower Floridan Aquifer
Bolder Zone
Surficlal Aquifer
Intermediate Confining Unit
Floridan Aquifer System
Upper Floridan Aquifer
Middle Confining Unit
Lower Floridan Aquifer
Bolder Zone
USDW

Intermediate Confining Unit

Hawthorn Formation (Upper
Confining Unit|
Floridan Aquifer System
Upper Floridan Aquifer
Middle Confining Unit
Lower Floridan Aoulfer
Depth Below
Land Surface (ft)



0-270
270-990
990-77?

990-1530


1100-1199

1530 - 2450
2450-???
0-270






0-50
50-200

200-450
450-700
700-1000




0-275
275 -B50

B50-1S50
1550 - 1990
1990-3900

2900-3500








2500 -3100
0-105
105-910
910-3190




1750.1415,2170,
1640









Thickness (ft)



175 - 270
600-1050
2500-3000

500-500
120-300
150-200
100-270


1000 - 1200 lower
300 -500 (Boulder Zone]

0-120

0-130
0-130
0-20
0-100
50
150

250
250
300




275
575

700
440
1910

600
150-B30
600-700



500-700
0-900
1800
300-650
105,180
805,590
2280








300





Hydraulic
Conductivity K
(ft/day)











0.003-3
(V)1.3x10J-Q.24(n=B)





148-2900


























V 2x10*- 2*10* (n=9),
1.3x10* (n=S)













V: 0.089- 8.8e-5



V: 0.80, H: 0 73

Trartsm Isslvlty T
(ffrday)






10000 -60000 2700,
10000, 31000





3.2x108 - 24.6x1 0s
(boulder zone)




5800-160000















10000-60000



3.2x10e-24x10s



10000-100000 32000
-132000, 24000,64800
491 X


3.2x10° -24x10*














10000-60000


Effective
Porosity









0 2 - 0.45
0.5. 0 3 - 0.4
0.336 - 0.464
Avg 0.402 (n=6)





















030



0.30
























0.32

Notes


Salinity (mg/L)


1840




3800

11800-35600













Temp(°F)
74. 61.3, 60.5.
60.6


TernpfF) 98-73
73-67

67-63
63-58
58-60
53, 74. 61.3, 60.5,
60.6




















Geraghty & Miller
1975

Meyer 1989


>
IN)

-------
    Appendix Table 2-2 Pinedas County


1
















z



















Authors
Hutaimsoa C B and
Tronmet j T
















KnochBimin. LA. and
Robvnoii. J.L



















rate
Uodel Analysis ol Hy«uKe Propertiei of a
Leaky Aquifer Sydem. Smsote County.
Florid*














Description of Anixfropy and Hefef ogcn*ity
and Theif Bled on Ground WBer Flow and
Anas of Contribution to Pubfc Supply We*, in
a Karat Carbonate Aiiiifef System


















Date

December, 193Z
















JamHy. 1996



















Source

USGS WSP 2340
















USGS WISP 2475



















Hydrogeologlc Untt

SurftdJlAquHv

Surficial AoLJiter
McnnUate ConlMng Untt
SnniconBnmg Unit
Tambml-
-------
    Appendix Table 2-2 Pinedas County


3































4










Authors

Mickey, JJ.






























Knochenmus LA and

1









TiUe
•tydrogeology and Results of Injection Tests at
Waste Injection Test Sites in Plnrtlas County.
Florida





























Transmissivity and Water Quality of Wrter-
Prcducing Zones in the Intermetiate Aqwfer
System, sarasota County. Florida









Date

1962































Warl-98










Source

USGSWSP2183































USGSWRI 98-4091










Hydrogeorogic Unit



SurScial AquWer
Intermediate Confining Unit



Hanlhom Formation (Upper Confining Unit)


Florida! Aoutter
Upper Ftortdai AquMer

Tampa (Zone A)

S^nee^miconfiningZone)

Suwinnee (Zone B)

Oeala ISemicDnfiningZone)
Avon Park (Zone C)
Avon Park (Seniconfinlng Zone)

Avon Park (Zone D)

MfcMe Confining Unit

UkeCity

Lower Flottdtn Aquifer
acts mar

Intwrrediato Conflning Unit

Confining Unit
Producing Zone 1
Confining Unit
Tamianu-upper Havrfhorn Atiiifer
(Producing Zone 2)

Confining Unit
Lower Ha^riorn-upper Tampa Aquifer
(Producing Zone3)
Uwt, Tanva Semlconfining Unit

Depth Below
.and Surface (ft)



0-S5




35-200






300-350


3EO-500

500-750

750-1250





1250-2000


2000-3260












Thickness
<«>



20-85




115





112-245.AV9
180
SO


50-75.AvgSO
250
300 - 3BS, Avg
330
100


52 - 121. Avg 70


750


1260

400


80

200


150


Hydraulic
Conductivity K
(ftfday)



V: 0.36 -13. Avg 2.6
H:13-33

0.00011-0.021
(n=12), Avg
0.0083
(Clause* 10*-
2.8i10J[n=16],
Avg 7.6x10J





0.0013



0.1-1






6.6x10'', 4.0x10'',
3.0x10", 3.3x1 03,
S.2X101. 1.1.2,0














Transmissivity T
(f^Iday)














21000 -«200, 29000,
29000,25000-30000






900000-1200000
Avg 1000000









2000-3000




HBO- 8000,8000

100- 26.000 (n= 18),
200-5000,740-2400,
500-3500

1300 - 6200 (n-4). 5600
-15400,500-10000


Effective
Porosity



0292.0.322











056, 0.31
0.22 -0.36, Avg
0.3


0.19. 024. 0.30
022- 0.36, Ava
0.3
0.15, 0,1*. 0.21
036.0.33


0.22. 0.39


















Notes


Sallnrtvfmg'L)
25. 32. 259. 404, 3040,
210. 120.




52





450. £540. SOB. 969.
32900. 1530, 6530

19000

19000-20000,35500.
36400. 30400. 26700


20001-21000,39200,
38200. 35100, 41800,
37900. 37SOO
21000-25000

39800, 43500. 38600.
42500

25000-31000








Ornnftv










1.003.1.0.
1.0. 1.0 IB.
0998.
1.002


1.025,
1.024,
1.024.
1.020.
1.018

1.025,
1.025,
1.025,
1.026

1.026,
1.026,
1.026,
1.026




























njectlon Zone














Barr. 1996. Duerr anSothers. 1938

Barr, 1996. Duerr and others. 1988, \Afelansky. 1983


3arr, 1996, VMansty, 1933


to

-------
     Appendix Table 2-2 Pinellas County


s







































6








Authors

Hulehinson. C.B.







































Bmska, J.C. and
Bametle, H.L








Title
Assessment of hyd»0e°lD9c CondHionB with
Emphasis on Water Quaity and Waslewtf er
Insertion. Southwest Sarascta mtd West
Charlotte Courtws, Florida






































Hycaogeokigy and Analysis of Aquifer
cnaraaersSics in West-Central MneJIat
County. Florida








Date

1991







































January 1. 1999








Source

USGS OFR 90-709







































USGS OFR 99-1 B5








HydrogeoJogic Unit




Surttelal Aquifer
intermediate Confining Unit

Senuconfining Unit



Tan-n^M^A^e,


S^con-m-gUnr,



Low* Hawthorn-upper Tarnpa Aquifer



Loftier Tampa Semiconfjninfl Unit
FloMan Aquifer System
upper norJoan taura

Suwannee Permeable Zone






Lower SuwBnnee-Ocala Semiconhning Uni




Avon Park Upper Permeable Zone
Avon Park Highly Permeable Dolomite
mam* ConOnftw un*
IwwHorMin footer
Surfcial Aquifer
Irdemedtate CcariMng Unit
Horidan Kourfer System
Jbvtotf RArtrfAn Armtfm,
Upper Heaatn tufiBtr
Tampa (Zone A)
Sunanitee (Semiconfining Zon* BJ

SUHOmiee (Zone 8)
Depth Below
Land Surface (ft)




0-50


SO-S)



60-100


100-240



24O410



410-500



500-750






750-1100




1100-1*00
1400-2075
207S2400
Z4DO-''







350-547

Thickness
m




50


10



40


140



170



90



250






350




300
675


50
SO- 140 Avg
90



115-250Avg
180
125-TTOAvg
150

50-75 A*s
62
Hydraulic
Conductivity K
(ft/day]





























H:65
V0.01.0O1. D.09,
O.S7. 221, D28.
0.09. 0.06. 0.06.
O.O3, 0.02. 0.01. 0.1
0.01. 0005
H- 0.023. OO3. 0.11.
025. 0.57, 0.14.
0.09. 0.06, 0.06.
0.02. 0.01 , 0 19
0.52, 023. 0.1. 0.08.
0.007.
H:100


V: 0.36 - 13 Ht
13-32
V: 1.3,10^-0.9,10



H:1B
Vi1.3,10*-2 H;


TransmissivityT
(tf/dayj




1340-1850,1100

7800, 5500. 1260.
3320, 3BOO. 1525.
1608.2970


200,650,300.400.
650. 550, 800, 5000






8200. 5600. 1000O



17900.15400



13000. 8900. 72000,
13000











SWOO. 48000, 80000.
67000.24000.
150000, 140000,
300000.

37000O





10000-40000


5000
Effective
Porosity































057. 0.4. 0.45.
0.37.0.37,0.37.
0.31.024,022.
022, 022. 027.
0.08,0.43, 0.03.
028,024.028.
022.025














Notes



saMtvimofl-i
•300




660, 1200, 1300, 390,
1900.660,1240,228.
326. 3000. 21000, 500,
546,458,650.756,
791.590.484.423.
406, 1630, 3240. 980,
330.4700.2040.5500

2170.1700.420.1400.
2200, 2300, 1900,
2750. 2330. ZOSB. 030,
3000. 21000. 2900.
2750.2930,2058,
1600.1200.250,1700,
2170. 3600, 2200,
1910,1700,4000,1200



3210.2900.2500.
1600.2300.3780.
3520,21000,3000,
1500, 10900, 4490.
1500. 15000. 14000


CH2M HO. me.. 1986.
Gerar/ityandUDer.
Inc. 1985, Hutehinson

LawEn^onmental, Inc.
T98S, Poa.BucUey,
Schuri and Jermgan.
Inc. 1982

35000, 13OO, 37500.
321W.34090.2100.
3000, 25200, 32800.
35000,33300,35200,


SaRmh/f.man.1


1000-10000^100-
400 It Us











































Imjedian
Zone











>
-k

-------
Appendix Table 2-2 Pinellas County

1
a
9
10
11
Authors
Bair. GL.

Duerr. A D. and Enos
G.M.
Mickey, J J.
Duerr. A O.
TrHe
Hydrcgeology of trie Surficial and Intermediate
Aquifer Systems in Saiasclaafld Adjacent
Counties. Florida
Hydrogeology and Simulated Development of
theBracldsri Ground-Water Resources in
PheHas County. Florida
Hydrofleology of the Intetmedate Aquifer
System and Upper Fforidan Aquifer. Hardee
and De Soto Counties. Honda
Hydrogeology. Estimated Impact, and Regiona
Well Monitoring of Effects of Subsurface
rtasrewaler Injection. Tampa Bay Area, Florida
Types of Secondary Porosity of carbonate
Rocks in Injection and Test Wills in Soutnem
Peninsulat Florida
Date
1xian-96
Jan 1 1991
1991
19B1
1995
Source
uses wro £6-4063
USGSWRI91-4026



USGS WRl 30-f 104
USGS V\FI 80-11 3
USGS UVRI 94-4013
HydroeeolOBic Unit
SuiflBlal A
-------
    Appendix Table 2-3 Brevard County

1









2










3








4



B





8





Authors
Duerr, A.D.









Schiner, G.R.










Duncan. J.G., Evans,
WL-.Tajtor, K-L.








Tibbais, C.H



Adams, Kann





Lukasiewicz, J. and
Adams, K.S.





Title
Types of Secondary Porosity of Cartonate Rocks in
njectjon and Test Wells in Southern Peninsular Florida









Geotiydrology at Osceola Counly. Florida










Geologic Framework of tfie Lower Roridan Aquifer
System, Brevanl Couniy, Flotida








Hydrogedogy of the Rorioan Aquifer System in East-
Central Florida



A Three Dimensional Finite Difference Row Model of
the Surficial Aquifer In Martin County, Florida




HydrogeMogic Data and Information Collected from the
Surficial and Roridan Aqiifer Systems, Upper East
Coast Planning Area





Date
1995









1993










19*1








1990



March-92





March-96





Source
USGS WRI 94-4013









USGS V\RI 92-4076










Florida Geological Survey Bulletin
No. 64








USGS Prof. Paper 1403-E



SFWJMD Technical Publication 92-
02




SlftFMD Technical Publication 96-
02 (VvRE S337)





Hydrogeologic Unit
Surficul Aquifer
Intermediate Confining Unit

Floridan Aquifer System
Upper Floridan Aquifer
Middle Confining Unit
Loiter Romfcm Aquifer
Bolder Zone

USDW
Surficial AquHer

Intenmdlata Confining Unit
Floridan AquHer System

Upper Floridan Aqutter

Middle Confining Unit
Lower Horidan Aquifer
Bolder Zone
USDW
Surficnl Aquifsr
IntumtedUte Confining Unit
Floridan Aquifer Sys»m

Upper Floridan Aquifer

MFddte Confining Unit
Loner Floridan Aquifer
Boulder Zone
Floridan Aquifer System
Upper Floridan Aquifer
Middle Confining Unit
Lower Floridan AotJfer
Surficial Aquifer





Surficial Aquifer
Intermediate Confining Unit
Floridan Aquifer System
Upper Floridan Aquifer
Mtddte ConflnfoD Unit
Lower Floridan Aoulfer
Depth Below
Land Surface
(ft)
0-95. 0-120
95 - 360, 120 -
250
360 - 2977 250 -
2906



2070 - 277Q
1190,1634.1670
1700, 1190









2500-3000


























Thickness
(ft)
95,120
360.130

2617,2656



700


30-270

40-300
2400-2900


300-350
450-700
1400-2100
500-800

90-150

2300-2900



110-250
1500-2OCO
B5-190
2300-2900

500-900









2700 - 3400
500
300

Hydraulic
Conductivity K
(ft/day)










H: 20- 100
V: 1.5x10"2-78x 10"7-
5x1 0s













H. 0.7S V: 0,07,
0.06,
V: <0.28 H: 0.28.
0.002B1






45,53,33,58,50,100,
78,73,32,40,42,52,
49,50,71,33,59,62,
97, 33, 33. 49, 35, 36,
121.53,53,48,37,38,
56,33,44,91.58.57,

126, 76







Transmissivfty T
(ff/day)










400,2000,1000



65000 - Z50QOO. 10000Q -
200000. 10000 - 35000,
10000-50000
5600,8900.43000
6500-60000,60000
1*1 07




50e3-1QOe3 1QOe3-
250e3





120000, 10000 - 400000,
74000. 210000, 510000,

30000-130000
3610,3743.1337,3476.
6016.12032.4679,2674,
4011,4011,6016.7353.
2005,11364.4011,5348,
4011,8021,3342,3342.
8021,2674,2005,26738,
1872,2406,3342,3342,
2005,3342,3342,4412,
10027, S214, 5749, 22727,
10695
394


34


Effective
Porosity



























0.20
0.1O-O.30

















Motes














































to

-------
Appendix 3

Weighted Mean Values

A primary literature review was conducted and all published values of hydrogeologic
parameters characterizing the hydrologic units in each county studied were tabulated in
this appendix and summarized in the following tables. The weighted means (Z ) of the
data were calculated to determine representative values to be used in the risk assessment.
The weighted mean method essentially reduces the effect of extreme data outliers (very
high or very low values). The following equation was used to develop the weighted
means for all hydrogeologic data (Mendenhall and Beaver, 1994).
                      ffl-2
0.5Z, + 0.75Z2
               0.75Z
                                  ,H_1
                                       0.5Z
Where:
Z
m
i
                      OT-1.5
               = Hydrogeologic datum
               = Total number of values
               = Chronological interger
                                                                    (Eqn. 1)
The above equation is not valid for data sets containing less than five values, therefore,
the following equation was used.
      0.5Z1+JTZ,+0.5Z11I
             r=2
            OT-1.0
                                                                    (Eqn. 2)
For data sets with two values, an average was calculated.

In the Intermediate, Upper Floridan and Lower Floridan aquifers, hydrogeological data
for the discretized geologic units within the aquifer are presented in the following tables.
Representative hydrogeologic data for the entire aquifer were then determined by
weighting the data in proportion to the thickness of the individual geologic units within
each hydrogeologic unit.

Weighted means for the data sets are color coded in blue, while representative values
used in the analysis are color coded in red.

Where there were insufficient data available, the following assumptions were made:

   •   Anisotropy ratios and porosity values were assumed to be consistent for
       equivalent aquifer units in each county, in the absence of site-specific data.
                                      A3-1

-------
•  Parameters for the horizontal and vertical hydraulic conductivities and porosities
   for each geologic layer in Brevard County were assumed to be consistent with
   data provided for the same equivalent depositional unit in Dade County,

•  A horizontal hydraulic gradient of 0.001 were assumed for the injection zone and
   the overlying units in Dade and Brevard Counties.

•  In Pinellas County, a horizontal hydraulic gradient of 0.05 in the injection zone
   was assumed. This accounted for the effects of pressure head due to injection. In
   the overlying units, a horizontal hydraulic gradient of 0.001 was used.

•  A porosity of 0.5 was assumed for the Boulder Zone for horizontal ground water
   flow. Conduit flows occur in the Boulder Zone due to cavernous pores or large
   fractures in the rock (Meyer, 1984, Maliva and Walker, 1998); therefore a larger
   porosity is required to address this issue.
                                   A3-2

-------
Appendix Table 3-1 Dade County
County: Dade
Hvdroqeoloqic Units






onionta oucti





rtic 1C ductiuifi
vertical t,ondiRDvraes










TransmisSuity




















Porosity









nity


2.* . 8



surficia


148
2900
iS>4











5800
160000
82900












50
105
150
175
180
200
270
270
275
830
232






73.04
98.06
8555












Tartar-
Aquifer




























































Intermediate

Unft








8.8E-Q5
O.I




10000
100000
SSOOO












150
450
575
590
BOO
600
700
805
1O50
$14







66.92
73.04
S998












Lower
upper Tampa
Aqurfer





























































Lower Tampa
Unit




























































































250
500
700
700
1100
650






0.3




66.92
62.96
64.94












Suwannee
(Semiconfining
Zone)





























12
3C
21




















18-









|ZoneB)





























0
3
>




















)

1415
1640
1750
2170
1728

Upper Floridan
Oca la
(Semiconfining
Zone)
0.45
9
55
121.8
42









2.700
10,000
10.000
10.000
10.000
24.000
31,000
32,000
49,100
60,000
60,000
64.800
100,000
132,000
40,060


150
200
175



1220





0.2
0.4E
0.33

0.3Z
















(Zone C) {Serriconffniag Zone)





























100
270
185









0.3
0.4
0.5
0.4







3800






































































Middle Confining Unit


8.37E-07
0.003
o.ro
3
4.3
6
23
J7
2.00E-05
1.30BO4
1.30E-04
2.00E-02
0.24
0.04















250
440
450
900
•IS?







0.336
0.464
0.45
0.-13

62.96
57.92
60.44



11800
35600






LowarF































100
200
300
330


7
1:
13
1!
1-






57.92
60.08
5900











oriBan

Bolder Zone
2.307
2,461
16.923
S53B










320E106
320EH36
1.30&07
2.46E»07
2.46E-KI7
136E+07









300
300
600
600
650
SS3
10
00
00
10
£

0.3




53
60.5
60.6
61.3
74
61.56








-------
      Appendix Table 3-2 Pinellas County
County: Pinedas
Hydrogeotogic Unte





Horizontal CGnductauities









Vertical Conductivities













Transrrissvrty


Surficial

2.00E-03
1O
13
13
13
32
33
33
159







0-36
0.36
036
13
13
13
E.SS




150
1100
1100
1340
laoo
1850
12-is









Irtermeolate
Tarriami- Lowa . _
Sen-confining upper Serriconfmfig Hamtom- XTJ!!!^
Unit HsWhom Unit upper Tampa S™K«,Ji™g
Arpjrfar Aquifer
0.005 17 01 18 10
56 59
125 335
64
23
t.OOE-04
1.1E-04
0.021
?.P1







2.40E-03 1.00E-O4
2.40E-03 1.10E-W
2.4QE-03 ' 1.30E-W
6.90E-03
100&O2
D.021
0.1
0.1
: -to
: 10
1.50
us

1260 100 . .200 15400
1525 200 i 200 17900
1606 300 500 16650
2970 400 740
3320 500 1300
3600 550 2400 :
5500 650 3500
7BOO 650 5000
3307 600 5000
1100 5600
1100 BZOO
5100 ' ' 8200
BOOO 9600
8000 10000 '
1708 4071
7259
400
7000
541S


Upper Roridar
Siwwmee ^ Ocala
^nqia (Zone A) (Serriconfining ._ D, (Sernccnfining
ZOTK) (2W«B) Zon(()
00013 70 0.007
0.1 65 0.01
0.4 1 002
0.20 67.5 0.023
0.03
0.06
0.06
O.OE
O.08
0.1
0.1
0.1
0.11
0.14
019
O23
025
O.S2
O.57
i " 1
O.16
13.78
O.DD3
0.3
0.45
121 -S
32
1.306-03 0.005
1.30E-03 0.01
0.1 • 0.01
0.4 : 001
1 0.01
2 0.02
2 0.03
3.73 0.06
O.09
0.09
0.1
02&
0.57
1
: 227
'. 2.5
0.39
500 5,000
5600 8.900
5600 13.000
10000 13.000
10000 i3,Doo
15400 72.000 ;
15400 17.9B3
21000
22000
25000
29000 " ' i
29000
30000
35000
40000
43200
20.928
539.999
29,000
30.000
51,000
75.000
100,000
850.000
198,727


Avon Park
(ZonaCI
25

















900,000
1200,000
1.050,000












Avon Park
(SemicDnSniog Zone]
100































Avon Park (Zone D)
100





"_









-














Middle Conflning Urdt












6.60E-07
4.00e-fl5
3.00E-O3
3.3OE-O3
5.20E-O2
i.i
2
0.34



1.00E«O1
9OOE+05
120E+06
7SOCO3










Lower Rondan



















2,000
3.000
370.000
EM.S»


.......


















	

	
	 	



.....

3.20E«OS
i.30E*07
2.«E*07
I.35.E-K)1:


"~_:






>

-------
Appendix Table 3-2 Pinellas County
County: Pinellas
Hydrofleologjc Units

Thickness

Porosity
Temperature
Salinity
Salinity

Suificial

3
20
25
50
so
60
60
85
100
132

0292
0292
0.322
0.322
031
74.48
90.32
25
25
32
120
210
259
300
404
500
3040
383

Int&Tnw
Serniconfining
Unit
5
10
10
150
upper Semico
HaiMtiorn Un
Aquifer
niiate
Lower
ifining Hawthorn-
it upper Tampa
Aquifer
40 29 .20
40 ! 115 170
SO : 140 170
SO 140 190
32.5 60 11
200
157
465
115
99
115
137
150
200
203
500
2
Lower Tampa
Unit
15
SO
90
240
103



9
0.21
0.3
0.41

0.
1

75.92
81.5
761
73.8

228 s:
326
330
390
406
423
458
484
500
546
590 •
650
660 '
660 :
7S6
791
980 ;
1200
1240
1300
1630
1900
2040
693
2 250
316
420
890
1200
1200
1400
1600
1700
1700
1700
1900
1910
2056
2058
2170
2,170
2170
2200
2200
2300
2600
2750
1533


Upper Floridan
Tampa (Zone A)
100
112
115
150
245
250
250
300
1100
256
,S— n,g S™«
10 50
90 SO
125 i 50
170 75
240 75
127 75
I 250
1 81 '
208
232
273
397
269
Ocala
Zone)
250
350
419
436
452
490
500
540
616
Awjn Park Avon Park
(Zone C) (Serrteonftning Zone)
300 100
386
343 :
Awon Park (Zone D)
22
121
72
515
892
957
1028
1155
1174
453 • 970
1848
0.26 0.22 0.19
0.26 i 0.36 0.24
0.31 '029 6.3
0.31
0.41
0.31
0.49
0.29
029
0.3
0.42
0.39
0.35
"
0.22
0.03
0.09
0.22
022
0.22
0.22
024
024
024
025
025
027
027
028
6.28
0.31
0.34
0.36
0.37
0.37
0.37
0.37
0.36
0.4
040
6.43
0.45
0.48
0.49
6.43


0.15 026 : 0.22
6.14 0.33 ; 0.39
0.21 0.30 : 0.31
0.16
021
0.02
0.07
6.11
0.20
0.24

0.14

.


.
0.2S
76.06
83.12
82.4
87.8
450
503
9S9
1120
1530
5530
6540
7700
32900
5136
450
1500
1500
1600
2300
2500
2900
3000
3210
3520
3780
4490
10900
15000
19,000
' 21000
26700
30400
35500
384OO
10755
19OOO
19000 ;
20000
37800
37900
38100
38200
39200
41600
34892
35480
1800
18000
20OOO
20000
21000
21000
25200
30000
32100
32800
32800
33300
34090
23481
21000
39800
43500
38600
42500
36300

Middle Confining UnK

750
0.034
0.45
O.317




21000
25000
23000

Lower Randan

1260
-




27
31
29C








-



no
too
»6
.
-
.

-------
      Appendix Table 3-2 Pinellas County
County: Pinellas
Hydrogeotoojc IWts



Salinity


Density




USOW
below land surface



Surficial





0.997
0.996
0-998
0.997
0.996
0996






Intermediate
SerriconfhiriEJ upper Semtconfining Hawthorn-
Unit Hawthotn Unit upper Tampa
AquifW Aquifer
3000 2760
3240 2900
4700 2330
5500 2830
21000 3000
16B5 4000
103OO
21000
2609











Lower Tampa
Semkonfining
Unit















Tampa (Zone A) (Serniconfiniig ^^ g.




0.998 1.025
1 1024
1 1.024
1.002 1.02
1.003 1,018
1.013 1.022
1.003
100
140
540
590
1013
1053
1300
680

Upper Florida!
Ocala
Zone)















Awn Park
(ZoneC)



... _ _
1.O25
1.025
1.025
1.025
1.028
1.02S







Avon Park
(Senicontinrig Zone)
35,000
35000
35200
37500
29741













Avon Park (Zone D>




1.026
1.026
1.026
1.O29
1.027



:: " '..:.:'..::



Mdole Confining unt















Lower Roti dan

..._.

'







"._""_.


a\

-------
Appendix Table 3-3 Brevard County
County: Brevard
Hydroaeolosic Units


















Horisjrtal Conductivities





















Vertical Conductivities








Transmissivity







SurtTcial

20
32
33
33
33
33
33
35
37
38
40
42
44
45
48
49
49
SO
50
52
53
S3
53
56
57
58
59
62
71
76
73
91
97
100
100
121
126
5$






400
3B4
488
562
564
57S
630
669
715
781
853
363
339
925
980
1000


Semiconfining
Onfl

























































upper
Hawthorn
Aquifer
























































Intemwdiata
Semiconfining
Unit




































7.30E-07
SOOE-03
1.50E-02
6.25E-D3

















Hawthorn-
uppflr Tampa
Aquifer

























































Lower Tampa
Unil























































! i 1
Upps Floridan
Suwawee Ocala p
Tampa (Zone A) IS«™orti-™g (^ne™ (Ssrriconfining ^ ^
; !



:


: ,

'
"




i
: 1
i j ;
i i
I '
' ' i
: i

i



j j
1 [
i
i ' !

i
i
i i

i ;
i : i
i i
! 1
: |
; i

i
3,289
3,637
4,932
5,416
6,551
6,635
6,912
7.346
7,436
7,594
8,172
8^01
9.0S4
9.422
9,615
9.827


Avon Park
(Sflmiconffning Zonfff

























































Avon Park (Zone D)






















.

































Middle Connnmg Unit

OK



































5.10E-O5





5.600
8.900
43,000
18.500











Lower Flondan

1.00E-D3
0.0028
O.O28
8.65E-03

'






























2.80E-01
0.005
0.06
OD7
0.12
01
6,500
30,000
60,000"
130.000
5SI.7SO











BolMrZone
500
BOO
SiC-










" -




	

'





















1.00E+07



_









-------
     Appendix Table 3-3 Brevard County
County: Brevard
Hvdtoejedogic Units































Transrmssivily
































Sanaa

1O42
1123
1150
1255
1315
1337
1372
1455
1482
1497
1532
1645
1724
1736
1765
1799
1359
1359
1872
1908
2000
2005
2005
2005
2006
2006
2303
2D26
Z313
2366
2406
2407
2644
2674
2674
2B08
2947
2991
3022
3075
3209
3342
3342
3342
3342
334!
347S
3476
3476
3610
3743
3944
4011
4011
4011
4O11
4319
4412
4679
4800
5214
5348
5348
5749


Semiconftnmg
IWt
































































upper































































Intermediate
Serrieonfnng
Unit
































































Lower
Hawthom-
upperTanra
































































Lower Tampa
Serriconnriing
Unit































































Upper Florida!
Suwannee ^ Ccata
Tampa (Zone A} (Semiconfriing 17*?^ o\ (Semiconflning
Zone) Zona)
S.953
10,000
10,000
10,000
10,050
10.243
10.896
10,919
11.064
11.115
11,564
11,691
12,271
12,560
12,566
12,609
12.693
13234
13,381
13,815
13,945
13,998
14.025
14266
14,307
14,316
14.588
14.707
14.887
14.BSO
15,001
15.983
16.567
16.B57
15,692
19.926
20.140
20.510
20,316
22,023
22.073
22.462
23,616
24.485
27,876
28,077
29,072
29204
30,626
31,754
31,866
34,537
34,774
35,000
37.279
37,365
3B.O45
41.313
43285
45.672
46.079
49.023
50,000


AinnPark
(ZoneC)
































































Avon Pork
(Semiconfining Zone)
































































Avon Park (Zone D)































































Mldfle Confinng Unit
































































Lower Roridan









" "





". . "








. ..








































edderZone







.














. . . .







































00

-------
Appendix Table 3-3 Brevard County
County: Brevard
Hvdroceoloqic Units



—






Thickness


Porosity
Temperature
Salinity





Surflclal

5829
6016
6016
6017
6217
6642
6819
7036
7313
7363
8021
8021
9292
9546
10027
10424
10589
0895
1364
2032
2777
3330
3343
22727
2673S
4100
90
as
120
150
112












Unit





















upper
Hawthorn
Aquifer




















Intermediate
Unit





40
130
300
360
2V!












Lower
Hawthorrt-
upper Tampa
Aquifer





















Lower Tampa
Semiconfining
Unit



















i
Upper Roridan
Suwaimee =,„,,.,„„ °cala .„,„ Parl. Al™, p.*
Tampa (Zone A) (Semtaonfinina oin™»™ (Semeonfinlno ,™ ™, ,„ . ™ . , , Avon Park (Zone D)
*^ ' ' Zorw) a (ZoneB) ' 2m " (ZoneC) (Eemconfining Zone)
50,000
61,729
62,037
65.000
67,905
71.065
72.090
74.000
74.337
84,124
38,225
100,000
100,000
120.000
200.000
210,000
250,000
250,000
400,000
510,000
42,025
\
300
360
J2S




2410
2300
2400
2617
2656
2900
2900
2134


-
1190
11BO
1634
1670
1700
149-5

Middle Confining Unit






110
250
450
500
700
900
335










Lower Roridan










14
15
20
21
17



-






Bolder Zone





35
190
700
291

X)
00
oo
00
50

02
- -- 	
-





-------
[ This page intentionally left blank ]

-------
Appendix 4

4.1. Total Vertical Time of Travel
Total vertical time of travel is defined as the time required for secondary treated
wastewater to migrate upward from the point of injection to the USDW and hypothetical
receptor wells.  Given the velocity and distance of travel, the time it takes to travel the
distance can be determined by dividing the distance by the velocity. To estimate the
vertical travel time (t) through each hydrologic unit, the thickness of the unit (b) is
divided by the seepage velocity (vs) (Eqn.  3). Seepage velocity is defined as the velocity
representing the average rate at which ground water moves (Fetter, 1994) and is
estimated by dividing the Darcy flow (q) by the porosity (n) of the hydrologic unit (Eqn.
4).  Porosity represents the ratio between the volume of voids over the total volume of the
media (Freeze and Cherry, 1979).  In this analysis, published porosity values were used.
Darcy flow is defined as fluid flow through porous media (e.g. sand) (Freeze and Cherry;
1979), taking into consideration that ground water flows through porous media, Darcian
assumptions must be applied. Darcy flow takes into account vertical hydraulic
conductivity (K) and the hydraulic gradient (I) (Eqn. 5).  Hydraulic conductivity
represents the ability of the media to transmit water (Fetter,  1994). Hydraulic gradient is
estimated by dividing the total pressure head (Hr) by the thickness of the hydrologic unit
(Eqn. 6).

                                                                    (Eqn. 3)
                                                                    (Eqn. 4)

                                                                    (Eqn. 5)

                                                                    (Eqn. 6)
4.2.  Total Pressure Head

Pressure head can be simply viewed as a driving force for vertical migration of treated
wastewater.  In this analysis, two driving components of pressure head were considered.
Pressure head due to injection (Hi) and pressure head due to buoyancy (Hs). These
components are described separately below.  The total pressure head acting on the
overlying hydrogeologic unit may be expressed as the sum of the buoyancy and the
injection components (Eqn. 7):
HT — H j + H L
(Eqn. 7)
                                      A4-1

-------
4.2.1. Pressure Head Due to Injection
Injection-derived pressure is a controlling force that drives the wastewater plume
throughout the regional ground water system.  As millions of gallons of water are
injected into the aquifer, that volume displaces an equivalent volume of native water in
the formation. This causes a pressure build-up in the aquifer, which must be dissipated
throughout the aquifer unit.

The vertical migration component due to injection-derived over-pressuring was
calculated using the following leaky aquifer steady-state pressure drawdown/increase
equation (Gupta, 1995).
       Q
 H, =-2_ln| 1.123— I for—  < 0.05
      InT
     B
                                                (Eqn. 8)

                                                (Eqn. 9)
where:
= Injection rate
= Vertical hydraulic conductivity
= Thickness of aquifer
= Transmissivity of the receiving unit = K x b      (Eqn. 10)
= Distance from injection well
= Zero-order modified Bessel function of the second kind
  (Tabulated values)
                    = Leakage factor =
                                                (Eqn. 11)
              K'
              b'
= Vertical hydraulic conductivity of the overlying layer
= Thickness of the overlying layer
A distance of one hundred feet from the injection well (r) was chosen in Pinellas County,
where pressure due to injection occurs.  A distance of one hundred feet was chosen
because at this distance away from the injection point, it is assumed that steady upward
flow would be occurring. This value will also result in a conservative travel time
estimation. The closer one is to the injection point, the greater the effects of pressure due
to injection, resulting in a faster travel time. Representative injection rates of 112.5
million gallons per day (mgd) in Dade County, 7 mgd in Pinellas County, and 5 mgd in
Brevard County were used (Starr et al., 2001, Florida Department of Environmental
Protection, 2001 and Florida Department of Regulation, 1989). In Dade and Brevard
Counties the pressure head due to injection is negligible due to injection into the Boulder
Zone. The Boulder Zone is highly karstified with cavernous pores and wide fractures,
which does not constrain the flow of injected effluent; therefore negligible pressure build
up will occur (Singh et al., 1983; Haberfeld, 1991).
                                      A4-2

-------
 4.4.2. Pressure Head Due to Buoyancy

 The buoyancy pressure head component, related to variations in fluid temperature and
 fluid density, also influences upward migration of the injectate. The wastewater injected
 into the aquifer is relatively fresh in comparison to the native ground water found in the
 injection zone (Florida Department of Environmental Protection, 1999a).  As a result, the
 less dense injected wastewater rises above the denser, native ground water. In hydraulic
 terms, the fresh water is more buoyant than the salt water.

 Density is also dependent on temperature: warm water is less dense than cold water. The
 temperature difference between the warm injected wastewater and the comparatively
 cold, native formation water is yet another driving force for the upward migration of the
 plume.

 Upward pressure heads due to the buoyancy (from salinity and temperature differences)
 were calculated using the following derived equation (Hwang and Hita, 1987):
                                                                    (Eqn. 12)
           A,
where:
HB
              P
              h
= Pressure head due to buoyancy (salinity and temperature
  gradient)
= Density of native (n) and injected (i) fluid
= Height of injected fluid (through each hydrologic unit)
Steady state conditions were assumed in this analysis. Under steady state conditions, no
mixing or dispersion occurs and the injectate has a continuous path to the hypothetical
water supply well or USDW. Travel times were estimated through each hydrologic unit.
Therefore a simplifying assumption, valid for steady state conditions, was that the height
of the injected fluid is the thickness of the hydrologic unit.

There is a natural salinity and temperature gradient in the native fluid.  The native fluid in
the injection zone has salinity comparable to sea water and becomes comparable to fresh
water at the surficial aquifer.  The injected wastewater has salinity comparable to fresh
water therefore the pressure head due to buoyancy (salinity gradient) will decrease as the
injectate moves closer to the hypothetical water supply well. The same result will occur
with respect to temperature gradient. The temperature of the native fluid in the injection
zone is approximately 60 degrees Fahrenheit and can reach up to 80 degrees in the
surficial aquifer. The injected wastewater has a temperature of 80 degrees. As the
injected wastewater moves closer to the hypothetical water supply well, the pressure head
due to buoyancy (temperature gradient) will decrease.  The buoyancy calculations were
based on the discretization of the density gradient due to temperature and salinity
difference.

In this analysis, two scenarios were considered: 1) porous media flow and 2) bulk flow
through preferential flow paths.  To assess the two scenarios, primary porosities and
                                      A4-3

-------
hydraulic conductivities and secondary porosities and hydraulic conductivities were used
in the above equations, respectively. The results are presented in the following tables for
Dade, Pinellas and Brevard Counties.
                                       A4-4

-------
        Appendix Table 4-1  Vertical Travel Time to Receptor Well
         (Scenario 1: Porous Media Flow)
        Dade
Hydrogeologic Units
Biscayne Aquifer
Intermediate Confining Unit
Upper Floridan Aquifer
Middle Confining Unit
Lower Floridan
Boulder Zone
Injection Fluid Travel
(bis)
From (feet)
230
840
2060
2550
2750
3000
To (feet)
100
230
840
2060
2550
2750
Vertical
Hydraulic
Conductivity
(Kv)
(ft/day)
15
0.10
0.42
0.04
0.10
65
Porosity
(n)
0.31
0.31
0.32
0.43
0.40
0.20
Aquifer
Thickness
(effective) (b)
(feet)
130
610
1220
490
200
250
Transmissivity
(T)
(fftdayj
2550
61
512
20
20
16250
HB
(feet)
1
5
19
23
15
12
H,
(feet)
0
0
0
0
0
0
HT
(feet)
0.66
4.69
18.5
22.5
14.6
12.0
Hydraulic
Gradient
(I)
0.004
0.008
0.015
0.046
0.073
0.048
Darcy
Velocity
(q)
(5/day)
0.058
0.001
0.006
0.002
0.007
3.13
Seepage
Velocity
K>
(ft/day)
0.188
0.002
0.020
0.004
0.018
15.7
Travel Time (t)
1.9 Years
674 Years
168 Years
314 Years
30 Years
16 Days
                                                                                                                            Travel Time  1,188  Years
        Pinellas
Hydrogeologic Units
Surficial Aquifer
Intermediate Confining Unit
Upper Floridan Aquifer
Injection Fluid Travel
(bis)
From (feet)
56
275
1250
To (feet)
30
56
275
Vertical
Hydraulic
Conductivity
(Kv)
(ft/day)
7
1.2
0.3
Porosity
(n)
0.31
0.31
0.226
Aquifer
Thickness
(effective) (b)
(feet)
26
219
975
Transmissivity
(T)
(ft2/day)
182
263
293
HB
(feet)
0.1
1.8
15.6
H,
(feet)
0
0
533
HT
(feet)
0.10
1.82
548
Hydraulic
Gradient
(0
0.004
0.008
0.563
Darcy
Velocity
(q)
(ft/day)
0.027
0.010
0.169
Seepage
Velocity
(Vs)
(ft/day)
0.087
0.032
0.747
Travel Time (t)
297 Days
18.6 Years
3.58 Years
I
                                                                                                                            Travel Time   23   Years
        Brevard
Hydrogeologic Units
Surficial Aquifer
Intermediate Confining Unit
Upper Floridan Aquifer
Middle Confining Unit
Lower Floridan
Boulder Zone
Injection Fluid Travel
(bis)
From (feet)
130
340
665
1000
2460
2754
To (feet)
100
130
340
665
1000
2460
Vertical
Hydraulic
Conductivity
(Kv)
(ft/day)
13
0.10
0.20
0.04
0.10
65
Porosity
(n)
0.31
0.31
0.26
0.43
0.40
0.20
Aquifer
Thickness
(effective) (b)
(feet)
30
210
325
335
1460
294
Transmissivity
(T)
(ft2/day)
390
21
65
13
146
19110
HB
(feet)
0
2
6
11
45
47
HI
(feet)
0
0
0
0
0
0
HT
(feet)
0.125
1.56
6.13
11.0
45.4
46.9
Hydraulic
Gradient
(I)
0.004
0.007
0.019
0.033
0.031
0.160
Darcy
Velocity
(q)
(ft/day)
0.054
0.001
0.004
0.001
0.003
10.4
Seepage
Velocity
(Vs)
(ft/day)
0.175
0.002
0.015
0.003
0.008
51.9
Travel Time (t)
172 Days
240 Years
61 Years
301 Years
515 Years
5.67 Days
                                                                                                                            Travel Time  1118  Years

-------
Appendix Table 4-2  Vertical Travel Time to USDW
 (Scenario 1: Porous Media Flow)
Dade
Hydrogeologic Units
Upper Floridan Aquifer
Middle Confining Unit
Lower Floridan
Boulder Zone
Injection Fluid Travel
(bis)
From (feet)
2060
2550
2750
3000
To (feet)
1500
2060
2550
2750
Vertical
Hydraulic
Conductivity
(Kv)
(ft/day)
0.42
0.04
0.1
65
Porosity
(n)
0.32
0.43
0.4
0.2
Aquifer
Thickness
(effective) (b)
(feet)
560
490
200
250
Transmissivity
(T)
(fftday)
512.4
19.6
20
16250
HB
(feet)
18.5
22.5
14.6
12.0
H,
(feet)
0
0
0
0
HT
(feet)
18.5
22.5
14.6
12.0
Hydraulic
Gradient
(I)
0.015
0.046
0.073
0.048
Darcy
Velocity
(q)
(ft/day)
0.006
0.002
0.007
3.13
Seepage
Velocity
(vs)
(ft/day)
0.020
0.004
0.018
15.7
Travel Time (t)
77 Years
314 Years
30 Years
16 Days
                                                                                                                    Travel Time   421   Years
Plnellas


Hydrogeologic Units


Upper Floridan Aquifer


Injection Fluid Travel
(bis)

From (feet)
1250

To (feet)
680
Vertical
Hydraulic
Conductivity
(Kv)
(ft/day)
0.30


Porosity
(n)

0.226

Aquifer
Thickness
(effective) (b)
(feet)
570


Transmissivity
(T)
(frVday)
293



He
(feet)
16



H,
(feet)
533



HT
(feet)
548

Hydraulic
Gradient
(I)

0.56

Darcy
Velocity
(q)
(ft/day)
0.17

Seepage
Velocity
(vs)
(ft/day)
0.75



Travel Time (t)

2 Years
                                                                                                                    Travel Time
Years
Brevard
Hydrogeologic Units
Lower Floridan
Boulder Zone
Injection Fluid Travel
(bis)
From (feet)
2470
2754
To (feet)
1500
2470
Vertical
Hydraulic
Conductivity
(M
(ft/day)
0.1
65.00
Porosity
(n)
0.4
0.20
Aquifer
Thickness
(effective) (b)
(feet)
970
284
Transmissivity
(T)
(ft2/day)
146
19110
HB
(feet)
45
47
H,
(feet)
0
0
HT
(feet)
45
47
Hydraulic
Gradient
(I)
0.03
0.160
Darcy
Velocity
(q)
(ft/day)
0.00
10.378
Seepage
Velocity
(vs)
(ft/day)
0.01
51.892
Travel Time (t)
342 Years
5 Days
                                                                                                                    Travel Time   342   Years

-------
        Appendix Table 4-3  Vertical Travel Time to Receptor Well
        (Scenario 2: Preferential Flow Paths)
        Dade


Hydrogeologic Units


Biscayne Aquifer
Intermediate Confining Unit
Upper Floridan Aquifer
Middle Confining Unit
Lower Floridan
Boulder Zone

Injection Fluid Travel
(bis)

From (feet)
230
840
2060
2550
2750
3000
To (feet)
100
230
840
2060
2550
2750
Vertical
Hydraulic
Conductivity
(Kv)
(ft/day)
15
2.38
2.38
1.5
0.1
65


Porosity
(n)

0.31
0.10
0.10
0.10
0.10
0.2
Aquifer
Thickness
(effective)
(b)
(feet)
130
610
1220
490
200
250


Transmissivity
(T)
(ft2/day)
2550
61
512
20
20
16250



HB
(feet)
1
5
19
23
15
12



H,
(feet)
0
0
0
0
0
0



HT
(feet)
0.7
4.7
18.5
22.5
14.6
12.0

Hydraulic
Gradient
(I)

0.004
0.008
0.015
0.046
0.073
0.048

Darcy
Velocity
(q)
(ft/day)
0.058
0.018
0.036
0.069
0.007
3.131

Seepage
Velocity

-------
     Appendix Table 4-4  Vertical Travel Time to USDW
     (Scenario 2: Preferential Flow Paths)
     Dade
Hydrogeologic Units
Upper Floridan Aquifer
Middle Confining Unit
Lower Floridan
Boulder Zone
Injection Fluid Travel
(bis)
From (feet)
2060
2550
2750
3000
To (feet)
1500
2060
2550
2750
Vertical
Hydraulic
Conductivity
(Kv)
(ft/day)
2.38
1.50
0.1
65
Porosity
(n)
0.10
0.10
0.1
0.2
Aquifer
Thickness
(effective)
(b)
(feet)
560
490
200
250
Transmissivity
(T)
(ff/day)
512.4
19.6
20
16250
HB
(feet)
19
23
15
12
H,
(feet)
0
0
0
0
HT
(feet)
19
23
15
12
Hydraulic
Gradient
(0
0.015
0.046
0.073
0.043
Darcy
Velocity
(q)
(ft/day)
0.036
0.069
0.007
3.1
Seepage
Velocity
K)
(ft/day)
0.36
0.69
0.07
15.7
Travel Time (t)
4 Years
2 Years
8 Years
16 Days
                                                                                                                       Travel Time
14   Years
     Pinellas


Hydrogeologic Units


Upper Floridan Aquifer

Injection Fluid Travel
(bis)

From (feet)
1250
To (feet)
680
Vertical
Hydraulic
Conductivity
(Kv)
(ft/day)
2.38


Porosity
(n)

0.1
Aquifer
Thickness
(effective)

(feet)
570


Transmissivity
(T)
(ffrday)
2321



HB
(feet)
16



H,
(feet)
122



HT
(feet)
138

Hydraulic
Gradient
(I)

0.14

Darcy
Velocity
(q)
(ft/day)
0.34

Seepage
Velocity

-------
Appendix 5

Horizontal Travel Distance

The horizontal travel distance (X) is defined in this analysis as the distance of horizontal
migration corresponding to the vertical travel time.  The horizontal travel distance of the
injected wastewater can be estimated by multiplying the seepage velocity (vs) in the
horizontal direction by the vertical travel time (t) estimated earlier (Eqn. 13). Seepage
velocity is defined as the velocity representing the average rate at which ground water
moves (Fetter, 1994) and is estimated by dividing the Darcy flow (q) by the porosity (n)
of the hydrologic unit (Eqn. 14).  Porosity represents the ratio between the volumes of
voids over the total volume of the media (Freeze and Cherry, 1979). In this analysis,
published porosity values were used. Darcy flow is defined as fluid flow through porous
media (e.g. sand) (Freeze and Cherry; 1979), taking into consideration that ground water
flows through porous media, Darcian assumptions must be applied.  Darcy flow takes
into account horizontal hydraulic conductivity (Kh) and the horizontal hydraulic gradient
(i) (Eqn.  15). Hydraulic conductivity represents the ability of the media to transmit water
(Fetter, 1994). Simple substitution of the seepage velocity and Darcy flow equations into
Equation 13, will result in Equation  16.
(Eqn. 13)

(Eqn. 14)1

(Eqn. 15)

(Eqn. 16)
     n
      n
As in the analysis of vertical travel time, two scenarios were considered: 1) porous media
flow and 2) bulk flow through preferential flow paths. To assess the two scenarios,
vertical travel times respective to the two scenarios were used in estimating the horizontal
travel distances.

In Dade and Brevard Counties, a horizontal hydraulic gradient of 0.001 was assumed for
all the hydrologic units.  In Pinellas County, a horizontal hydraulic gradient of 0.05 was
assumed in the injection zone and 0.001 in the overlying units. A greater horizontal
hydraulic gradient in the injection zone accounts for the effects of injection pressure due
to the injection of millions of gallons of wastewater a day.

Primary porosities were used in this analysis (Eqn. 16) however, in the Boulder Zone a
porosity of 0.5 was assumed in Dade and Brevard Counties. A larger porosity in the
Boulder Zone takes into account cavernous pores or large fractures found in the Boulder
Zone (Meyer, 1984, Maliva and Walker, 1998).

The results of this analysis and a summary of the assumptions made are presented in the
following tables for Dade, Pinellas and Brevard Counties (Table 5-1, 5-2 and 5-3).
1 Same equation used in Appendix 4 (Eqn. 4)
                                      A5-1

-------
Appendix Table 5-1   Horizontal Migration
 (Scenario 1: Porous Media Flow)
Dade


Hydrogeologic Units


Biscayne Aquifer
Intermediate Confining Unit
Upper Floridan Aquifer
Middle Confining Unit
Lower Floridan Aquifer
Boulder Zone
Horizontal
Hydraulic
Conductivity

-------
Appendix Table 5-2  Horizontal Migration
(Scenario 2: Preferential Flow Paths)

Dade


Hydrogeologic Units


Biscayne Aquifer
Intermediate Confining Unit
Upper Floridan Aquifer
Middle Confining Unit
Lower Floridan Aquifer
Boulder Zone
Horizontal
Hydraulic
Conductivity
(KH)
(ft/day)
1,524
90.0
42
5
0.10
6,538

Hydraulic
Gradient
(i)

0.001
0.001
0.001
0.001
0.001
0.001


Porosity
(n)

0.31
0.10
0.10
0.10
0.10
0.20


Time
(t)
Days
2
3,335
3,379
711
2,746
16

Horizontal
Distance
(X)
ft
9
3,002
1,419
33
3
522
                                        Total Horizontal Distance   4,988
Pinelias
Hydrogeologic Units
Surficial Aquifer
Intermediate Confining Unit
Upper Floridan Aquifer
Horizontal
Hydraulic
Conductivity
(KH)
(ft/day)
29
4
22
Hydraulic
Gradient
(i)
0.001
0.001
0.05
Porosity
(n)
0.31
0.1
0.1
Time
(t)
Days
297
1,756
290
Horizontal
Distance
(X)
ft
28
70
3,195
                                        Total Horizontal Distance   3,293
Brevard


Hydrogeologic Units


Surficial Aquifer
Intermediate Confining Unit
Upper Floridan Aquifer
Middle Confining Unit
Lower Floridan Aquifer
Boulder Zone
Horizontal
Hydraulic
Conductivity
(KH)
(ft/day)
56
20.00
20
1
0.1
650

Hydraulic
Gradient
(i)

0.001
0,001
0.001
0.001
0.001
0.001


Porosity
(n)

0.31
0.10
0.10
0.10
0.10
0.20


Time
(t)
Days
172
3
724
682
46980
6

Horizontal
Distance
(X)
ft
31
1
145
5
47
18
                                       Total Horizontal Distance   247
                                           A5-3

-------
[ This page intentionally left blank ]

-------
Appendix 6

Uncertainty Analysis

Upper and lower boundary travel times to use for the risk assessment were computed
based on the results of the uncertainty analyses. For purposes of this risk assessment,
times of travel were computed by altering one parameter in each scenario. Vertical
hydraulic conductivity of the confining unit was the tested parameter for the porous
media scenario (Scenario 1). Porosity was the tested parameter for the preferential flow
path scenario (Scenario 2).

Vertical hydraulic conductivity was evaluated by computing travel times based on
variation of the mean vertical hydraulic conductivity by up to one order of magnitude
above and below the mean value calculated from review of the scientific literature.
Porosity was varied from 0.01 to 0.20, a range within typical porosity values found for
limestones and dolomites (Freeze and Cherry, 1979). for the travel times computed in the
preferential flow path scenario. Graphical representation of the uncertainty analysis time
of travel computations can be found in Appendix Figures 6-1, 6-2 and 6-3 for Dade,
Brevard and Pinellas Counties,

Upper and lower bounds of times of travel were computed from the results of the
uncertainty tests. The first step in developing these bounds is to determine the statistical
average time of travel (taverage) (Eqn. 17).
            MO
 average
                                                                     (Eqn. 17)
The tgo and tio values are the vertical travel times associated with the ninetieth and the
tenth percentile, respectively, within the range of the time of travel calculations for each
scenario. The resulting taverage value thus represents a statistical calculation that
incorporates the weight of the travel time variations across two orders of magnitude for
the lowest hydraulic conductivity unit, and across the reasonably expected range of
porosity typically associated with preferential (i.e.- secondary) flow.

The upper and lower bounds for time of travel are then computed based on the
relationship between taverage, computed in the uncertainty tests, and the vertical travel time
(t) estimated earlier.  Equations 18 and 19 depict the computations used to generate the
upper and lower time of travel bounds, respectively:
*upper   ' ~"~ I* average   V

Blower ~ * ~ \averase ~ V
(Eqn. 18)
(Eqn. 19)
                                       A6-1

-------
Appendix Figure 6-1
Uncertainty Analysis Results for Dade County
                        Vertical Hydraulic Conductivity Vs. Travel Time (Scenario 1: Porous Media Flow)
    4500.0
    4000.0
                                                                            Travel Time Range
                                                                                     (years)
                                                                          Upper End    2460
                                                                          Mean         1188
                                                                          Lower End    905
       0.0
         0.001
                                            0.01                                0.1

                                              Vertical Hydraulic Conductivity Kv (ft/day)
                                Porosity Vs. Travel Time (Scenario 2: Preferential Flow Paths)
    33.00
    32.50 -
    32.00 -
     Travel Time Range  Porosity
          (years)
Upper End   32         0.20
Mean       30         0,10
Lower End   28        0.01
    31.50
    28.00
                                                           A6-2

-------
Appendix Figure 6-2
Uncertainty Analysis Results for Pinellas County
                       Vertical Hydraulic Conductivity Vs. Travel Time (Scenario 1: Porous Media Flow)
    60.0
    55.0	
    50.0	
    45.0-
    40.0	
  E 35.0-
  ,± 30.0-
    25.0-
    20.0^
    15.0-
    10.0
Travel Time Range     Kv
           (years)   (ft/day)
Upper End  37.5       0.06
Mean       23.0       0.30
Lower End   19.8       3.00
       0.01
                                           0.1                                  1
                                             Vertical Hydraulic Conductivity Kv (ft/day)
                               Porosity Vs. Travel Time (Scenario 2: Preferential Flow Paths)
   7.50
   7.00
   6.50
   6.00
   5.50-
   5.00
                                                        A6-3

-------
Appendix Figure 6-3
Uncertainty Analysis Results for Brevard County
                  Vertical Hydraulic Conductivity Vs. Travel Time (Scenario 1: Porous Media Flow)
     4500.0
     4000.0
     3500.0
     3000.0
     2500tT
   Travel Time Range
          (years)
Upper End    2515
Mean       1294
Lower End    1023
     2000.0 -
     1500.0 -
     iooo:tr
      500.0 -
          0.001
                                           0.01                               0.1
                                             Vertical Hydraulic Conductivity Kv (ft/day)
                           Porosity Vs. Travel Time (Scenario 2: Preferential Flow Paths)
    139.00
    138.50
    138.00
    134.00
                                    Travel Time Range   Porosity
                                        (years)
                              Upper End    138.1       0.20
                              Mean       136.3        0.10
                              Lower End    134.6       0.01
                  0.02
                                                          A6-4

-------
Appendix 7

Fate and Transport

The fate and transport of representative stressors can be estimated by a first order decay
model (Eqn. 20), which estimates the final concentration (C) of the representative
stressors in correlation to vertical travel times estimated earlier. This first order decay
model is appropriate for analysis of the organic constituents, because it takes into account
natural attenuation processes such as biodegradation, hydrolysis and sorption (Suthersan,
2002).
                     C = C0e-klc                                      (Eqn. 20)
where:
C
Co
k
tc
= Final concentration of stressors
= Initial concentration of stressors
= Decay coefficient of stressors
= Travel time of stressors
Half-life (ti/2) is defined as the time it takes for stressors to reach half of the initial
concentration.  The decay coefficient (k) can be determined by rearranging Equation 20,
substituting the half-life in place of the travel time of stressors (tc) and equating the ratio
of the final versus initial concentrations to 0.5  (Eqn. 21). The decay coefficient (Eqn. 22)
is simplified by rearranging Equation 21. Published values for half-life are available and
were identified for the selected representative stressors (Howard et al., 1991).
                     C
                                                                      (Eqn. 21)
                    k =
                        0.693
                                                        (Eqn. 22)
The travel time of representative stressors (tc) are determined by multiplying the
retardation coefficient (R) by the effluent travel time (IE) (Eqn. 23).  In this analysis, the
effluent travel time is equivalent to the vertical travel time estimated earlier.
                    tc - R x tE
                                                       (Eqn. 23)
The retardation coefficient takes into account sorption, a natural attenuation process
which increases the travel time of stressors. The greater the travel time of stressors, the
more time there is for other natural attenuation process to occur, such as biodegradation
and hydrolysis to a lesser extent. Biodegradation results in the degradation of organic
material and may also mediate transformations in the state of inorganic material resulting
in decreasing concentrations over time. Hydrolysis is the process whereby organic and
inorganic solutes react with water resulting in degradation and transformation (Suthersan,
2002). Calculation for the retardation coefficient, for dissolved organic constituents, is
shown below in Equation 24 (Suthersan, 2002).
                                       A7-1

-------
                              n
where:        pb     - Bulk density  = p^l-n)
              ps     = soil density
              n      = porosity
              Kd     = Distribution coefficient = Kocf0i
              Koc    = Sorption coefficient
              foc     = fraction of total organic carbon
(Eqn. 24)


(Eqn. 25)



(Eqn. 26)
                                   n
                                                                     (Eqn. 27)
Sorption coefficients (Koc) were obtained from published values for each representative
stressor (Montgomery, 2000).  For purposes of risk assessment, conservative values
(indicating the least sorption) were selected to calculate the distribution coefficient and
therefore the retardation coefficient. Ultimately, this produces conservative estimates of
stressor concentrations at the receptors, since the data used relate to the lowest reasonably
expected retardation and the shortest travel time. The calculations incorporated a typical
value for sediment density of 2.63 g/cm3 (Freeze and Cherry, 1979). Weighted mean
porosity values (Appendix 3), based on unit thickness, were used in the calculations.
                                       A7-2

-------
(Scenario 1: Porous Media Flow)
Dad* County
Surrogate
Chloroform (ug/L)
Tetraehloroethylene (PCE) (|tg/L)
Chlordane (pg/L)
Arsenic (mg/L)
Dl(Mthylhexyl) Phthalate (DEHP) (ug/L)
Amrnonia (mg/L) (conservative behavior)
Nitrates (mg/L)(conseivative behavior)
Published Half-Life
in Groundwater
(W (days)
1800
720
2772
N/A
389
N/A
N/A
Published
Sorption
Coefficient
1.44
2.25
4.72
2.73
4.48
0.49
N/A
Fraction of
Total
Organic
Carbon (f^)
0.01
0.01
0.01
0.01
0.01
0.01
N/A
Distribution
Coefficient
0.014
0.023
0.047
0.027
0.045
0.005
N/A
Soil Density
(P.)
2.63
2.63
2.63
2.63
2.63
2.63
N/A
Porosity
(n)
0.33
0.33
0.33
0.33
0.33
0.33
N/A
Sulk Density
1.76
1.76
1.76
1.76
1.76
1.76
N/A
Retardation
Coefficient
(R)
1.08
1.12
1.25
1.15
1.24
1.03
N/A
Effluent Travel
Time 1o Receptor
Wens (y (years)
1188
1188
1188
1188
1188
1188
1188
Contaminant
Travel Time
(U (years)
1279
1331
1487
1361
1472
1219.1
N/A
Effluent Travel
Time to Receptor
Wells (days)
433620
433620
433620
433620
433620
433620
433620
Contaminant Travel
Time (U
(days)
466962
485716
542907
496830
537350
444965
N/A
Decay
Coefficient
(k)(day-')
0.0004
0.0010
0.0003
N/A
0.0018
N/A
N/A
Concentration
at Injection R.
(C0)
61.58
4.66
0.010
0.010
5.00
8.75
3.82
Concentration
at Supply Well
(C)
0.00
0.00
0.000
0.010
0.00
8.75
3.82
Pinellas County
Surrogate
Chloroform (ugTL)
retrtchloroethylene (PCE) (|ig(L)
Chlordane (pg/L)
Arsenic (mg/LJ
Di|2-ethylhexyl) Phthalate (DEHP) (pgfL)
Ammonia (mg/L) (conservative behavior)
Nitrates (mg/L)(conservaflve behavior)
Published Half-Life
in Groundwater
(tlc> (days)
1800
720
2772
N/A
389
N/A
N/A
Published
Sorption
Coefficient
(Kcd
1.44
2.25
4.72
2.73
4.43
0.49
N/A
Fraction ol
Total
Organic
Carbon (fK)
0.01
0.01
0.01
0.01
0.01
0.01
N/A
Distribution
Coefficient
(Kdf
0.014
0.023
0.047
0.027
0.045
0.005
N/A
Soil Density
(pj
2.63
2.63
2.63
2.63
2.63
2.63
N/A
Porosity
(n)
0.24
0.24
0.24
0.24
0.24
0.24
N/A
Bulk Density

-------
    Appendix Table 7-2  Representative Stressors Concentrations at USDW
    (Scenario 1: Porous Media Row)
Dade County
Surrogate
Chloroform (ug/L)
Tetrachloroethylane (PCE) (ug/L)
Chlordane (|ig/L)
Arsenic (mgIL)
Di(2-ethylhexyl) Phthalate (OEHP) (|ig/L)
Ammonia (mg/L) (conservative behavior)
Nitrates (mg/LKconservatrve behavior)
Published Half-
Life in
Groundwater
(tie) (days)
1800
720
2772
N/A
369
N/A
N/A
Published
Sorption
Coefficient
(Koo)
1.44
2.25
4.72
2.73
4.48
0.49
N/A
Fraction of
Total
Organic
Carbon 
1.44
2.25
4.72
2.73
4.48
0.49
N/A
Fraction of
Total
Organic
Carbon (fK)
0-01
0-01
0-01
0-01
0-01
0.01
N/A
Distribution
Coefficient
(Ka)
Soil Density
(PJ
0.014 2.63
0.023 2.63
0.047 2.63
0.027 2.63
0.045 2.63
0.005 2.63
N/A N/A
Porosity (n)
0-24
024
0.24
0.24
0.24
0.24
N/A
Bulk Density
(Pb)
2,00
2.00
2.00
2.00
2.00
2.00
N/A
Retardation
Coefficient
(R)
1.12
1.19
1.39
1.23
1-37
1.04
N/A
Effluent Travel
Time to USDW
fe) (years)
2.00
2.00
2-00
2.00
2-00
2.00
2.00
Contaminant
Travel Time
(tcKyears)
2.2
2.4
2.8
2.45
2.7
2.1
N/A
Decay
Coefficient (k)
(day'1)
0.0004
0.0010
0.0003
N/A
0.0018
N/A
N/A
Concentration
at Injection Pt.
(C0)
6.70
0.63
0.64
0.003
1.25
18.00
0.28
Concentration
at USDW (
C)
4-89
0.27
0.50
0.003
0.21
18.00
0.28
>
-L
Brevard County
Surrogate
Chloroform (|ig/L)
Tetracnloroethytene (PCE) (ugf L)
Chlordane (ug/L)
Arsenic (mg/L)
Di(2-etnylhexyl) Phthalate (DEHP) (ug/L)
Ammonia (mg/L) (conservative behavior)
Nitrates (mg/LKconservatlve behavior)
Published Half-
Life in
Groundwater
fta) (days)
1800
720
2772
N/A
389
N/A
N/A
Published
Sorption
Coefficient
(Koc)
1.44
2.25
4.72
2.73
4.48
0.49
N/A
Fraction of
Total
Organic
Carbon (I..)
0.01
0-01
0.01
0.01
0.01
0.01
N/A
Distribution
Coefficient
(KJ
Soil Density
(PJ
0.014 2.63
0.023 2.63
0.047 2.63
0.027 2.63
0.045 2.63
0.005 2.63
N/A N/A
Porosity (n)
0.36
0.36
0.36
0.36
0.36
0.36
N/A
Bulk Density
(Pb)
1.68
1.68
1.68
1.68
1.68
1.68
N/A
Retardation
Coefficient
(R)
1.07
1.11
1.22
1.13
1.21
1.02
N/A
Effluent Travel
Time to USDW
(tE) (years)
342
342
342
342
342
342
342
Contaminant
Travel Time
(W (years)
365
378
417
386
414
350
N/A
Decay
Coefficient (k)
(day-1)
0.0004
0.0010
0.0003
N/A
0.0018
N/A
N/A
Concentration
at Injection Pt.
(C0)
230
1.00
0.010
0.005
5.00
8.75
9.60
Concentration
at USDW (
C)
0.0
0.0
0.0
0.005
0.0
8.75
9.60
     N/A = not applicable

-------
j-ippcnuiA  iduic i--j  rvcpicac
(Scenario 2: Preferential Flow Paths)
Dade County



Surrogate
Chloroform (iig/L)
Tetrachloroethylene (PCE) (ug/L)
Ctilordane (ug/L)
Arsenic (mg/L)
Di(2-ethylhexyl) Phthalate (OEHP) (ug/L)
Ammonia (mg/L) (conservalive behavior)
Nitrates (mg/LHconservative behavior)

Published Half-Life
in Groundwater
(tia) (days)
1800
720
2772
N/A
339
N/A
N/A
Published
Sorption
Coefficient
(Koc)
1.44
2.25
4.72
2.73
4.48
0.49
N/A
Fraction of
Total
Organic
Carbon (foc)
0.01
0.01
0.01
0.01
0.01
0.01
N/A

Distribution
Coefficient

0-014
0-023
0.047
0.027
0.045
0.005
N/A


Soil Density
(P.)
2.63
2.63
2.63
2.63
2.63
2.63
N/A



Porosity (n)
0-3
0.3
0.3
0.3
0.3
0.3
N/A


Bulk Density
(Pb)
1.84
1.84
1.84
1.84
1.84
1.84
N/A

Retardation
Coefficient
(R)
1.09
1.14
1.29
1.17
1.27
1.03
N/A

Effluent Travel
Time to Receptor
Wells (tE) (years)
30
30
30
30
30
30
30

Contaminant
Travel Time
(tc) (years)
33
34
39
35
38
30.9
N/A

Decay
Coefficient
(k)(day-1)
0.0004
0.0010
0.0003
N/A
0.0018
N/A
N/A

Concentration
at Injection R.
(C0)
61.58
4.66
0.010
0.010
5.DO
8.75
3.82

Concentration
at Supply Wetl
(C)
0-63
0-00
0.000
0.010
0.00
8.75
3.82
Pine lias County
Surrogate
Chloroform (ug/L)
Tetrachloroethylene (PCE) (ug/L)
Chlordane (pg/t)
Arsenic {mgfL)
DI(2-ethythexyi) Phthalate (DEHP) (ug/L)
Ammonia (mg/L) {conservative behavior)
Nitrates (mg/L)(conservative behavior)
Published Half-Life
in Groundwater

-------
    Appendix Table 7-4  Representative Stressors Concentrations at USDW
    (Scenario 2: Preferential Flow Paths)
Dade County
Surrogate
Chloroform (ug/L)
Tetraehtoroettiytene (PCE) (pg/L)
Chtordane (ugA)
Arsenic (mg/L)
Di(2-eltiymexyl) Phthalate (DEHP) (pg/L)
Ammonia (mg/L) (conservative behavior)
Nitrates (mg/LK conservative behavior)
Published Half-
Life in
Groundwater
(do) (days)
1800
720
2772
N/A
389
N/A
N/A
Published
Sorption
Coefficient

1.84
1.84
1.84
1.84
1.84
1.84
N/A
Retardation
Coefficient
(R)
1-09
1.14
1.29
1.17
1.27
1.03
N/A
Effluent Travel Time
to USDW (IE) (years)
14
14
14
14
14
14
14
Contaminant
Travel Time
(tc) (years)
15
16
18
16
18
14.4
N/A
Decay
Coefficient
(k)(day-1)
0.0004
0.0010
0.0003
N/A
0.0018
N/A
N/A
Concentration
at Injection R.
(C0)
61.58
4.66
0.010
0.010
5.00
8.75
3.82
Concentration
at USDW (
C)
7.24
0.02
0.00
0.010
0.00
8.75
3.82
Pine Das County
Surrogate
Chloroform (pg/L)
Tetrachloroethytene (PCE) (pg/L)
Chtordane (pg/L)
Arsenic (mg/L)
Di(2-ethylhexyl) Phthalate (DEHP) (pgfL)
Ammonia (mg/L) (conservative behavior)
Nitrates (nig/LKconservative behavior)
Published Han-
Life in
Groundwater
(t1c) (days)
1800
720
2772
N/A
389
N/A
N/A
Published
Sorption
Coefficient
(Koc)
1.44
2.25
4.72
2.73
4.48
0-49
N/A
Fraction of
Total
Organic
Carbon (f«)
0-01
0.01
0.01
0.01
0.01
0.01
N/A
Distribution
Coefficient
(Kd)
0.014
0.023
0.047
0.027
0-045
0.005
N/A
Soil Density
(pj
2.63
2.63
2.63
2.63
2.63
2.63
N/A
Porosity (n)
0.25
0.25
0.25
0.25
0.25
0.25
N/A
Bulk Density
(Pb)
1.97
1.97
1.97
197
1.97
1.97
N/A
Retardation
Coefficient
(R)
1.11
1.18
1.37
1.22
1.35
1.04
N/A
Effluent Travel Time
to USDW (IE) (years)
0.47
0.47
0.47
0.47
0.47
0.47
0.47
Contaminant
Travel Time
(tc) (years)
0.5
0.5
0.6
0.57
0.6
0.5
N/A
Decay
Coefficient
(k) (day-1)
0.0004
0.0010
0.0003
N/A
0.0018
N/A
N/A
Concentration
at Injection Ft.
(C0)
6.70
0.63
0.64
0.003
1.25
18.00
0.28
Concentration
at USDW (
C)
6.23
0.52
0.60
0.003
0.83
18.00
0.28
Os
Brevard County
Surrogate
Chloroform (ug/L)
retrachkvoethylene (PCE) fyg/L)
Chtordanedig/L)
Arsenic (mg/L)
Di(2-ethyttiexyi) Phthalate (DEHP) (yglL)
Ammonia (mg/L) (conservative behavior)
Nitrates (rng/LKconservattve behavior)
Published Half-
Life in
Groundwater
(t1ffi) (days)
1800
720
2772
N/A
389
N/A
N/A
Published
Sorption
Coefficient
(Koc)
1.44
2.25
4.72
2.73
4.48
0.49
N/A
Fraction of
Total
Organic
Carbon (U
0.01
0.01
001
0.01
0.01
0.01
N/A
Distribution
Coefficient
(Kd)
0.014
0.023
0-047
0.027
0.045
0.005
N/A
Soil Density
(P.)
2.63
2.63
2.63
2.63
2.63
2.63
N/A
Porosity (n)
0.36
0.36
0.36
0.36
0.36
0.36
N/A
Bulk Density
(Pb)
1.68
1.68
1.68
1.68
1.68
1.68
N/A
Retardation
Coefficient
(R)
1.07
1.11
1.22
1.13
1.21
1.02
N/A
Effluent Travel Time
to USDW (IE) (years)
86
86
86
66
86
86
86
Contaminant
Travel Time

-------
Appendix 8.  Aquifer Recharge Calculations

To determine risk associated with aquifer recharge of treated effluent, the fate and
transport of representative stressors were conducted for a range of required setbacks of
200, 500 and 2,640 feet (0.5 mile). Utilizing hydrologic data for the Surficial Aquifer,
the fate and transport of the selected representative stressors can be estimated.

The time of travel to the horizontal setback distances (X) can be estimated by dividing
the setback distances by the seepage velocity (vs) (Eqn. 28). Seepage velocity is defined
as the velocity representing the average rate at which ground water moves (Fetter, 1994)
and is estimated by dividing the Darcy flow (q) by the porosity (n) of the hydrologic unit
(Eqn. 29). Porosity represents the ratio between the volumes of voids over the total
volume of the media (Freeze and Cherry, 1979). In this analysis, published porosity
values were used. Darcy flow is defined as fluid flow through porous media (e.g. sand)
(Freeze and Cherry;  1979), taking into consideration that ground water flows through
porous media, Darcian assumptions must be applied. Darcy flow takes into account
horizontal hydraulic  conductivity (Kh) and the horizontal hydraulic gradient (i) (Eqn. 30).
Hydraulic conductivity represents the ability of the media to transmit water (Fetter,
1994).  Simple substitution of the  seepage velocity and Darcy flow equations into
Equation 28 will result in Equation 31.
    X
                                                                     (Eqn. 28)
t =
Xn
Khi
                                                                     (Eqn. 29)1

                                                                     (Eqn. 30)2

                                                                     (Eqn. 31)
Once the time of travel to the predetermined setback distances (Appendix Table 8-1) has
been estimated, a fate and transport analysis can be used to determine the final
concentrations of representative stressors. The fate and transport of representative
stressors can be estimated by a first order decay model (Eqn. 32), which estimates the
final concentration (C) of the representative stressors in correlation to vertical travel
times estimated earlier. This first order decay model is appropriate for analysis of the
organic constituents, because it takes into account natural attenuation processes such as
biodegradation, hydrolysis and sorption (Suthersan, 2002).
                             -kif
                                                                     (Eqn. 32)J
1 Same equation used in Appendix 4 and 5 (Eqn. 4 and Eqn. 14)
2 Same equation used in Appendix 5 (Eqn. 15)
3 Same equation used in Appendix 7 (Eqn. 20)
                                       A8-1

-------
where:        C      = Final concentration of stressors
              CQ    = Initial concentration of stressors
              k      = Decay coefficient of stressors
              tc      = Travel time of stressors

Half-life (tm) is defined as the time it takes for stressors to reach half of the initial
concentration.  The decay coefficient (k) can be determined by rearranging Equation 32,
substituting the half-life in place of the travel time of stressors (tc) and equating the ratio
of the final versus initial concentrations to 0.5 (Eqn. 33). The decay coefficient (Eqn. 34)
is simplified by rearranging Equation 33. Published values for half-life are available and
were identified for the selected representative stressors (Howard et al., 1991).
                      C
                                                                      (Eqn. 33)J
                    k =
                        0.693
                                                        (Eqn. 34)J
The travel time of representative stressors (tc) are determined by multiplying the
retardation coefficient (R) by the effluent travel time (IE) (Eqn. 35). In this analysis, the
effluent travel time is equivalent to the vertical travel time estimated earlier.
                    tc = R x ts
                                                        (Eqn. 35)J
The retardation coefficient takes into account sorption, a natural attenuation process
which increases the travel time of stressors.  The greater the travel time of stressors, the
more time there is for other natural attenuation process to occur, such as biodegradation
and hydrolysis. Biodegradation results in the degradation of organic material and may
also mediate transformations in the state of inorganic material, resulting in decreasing
concentrations over time.  Hydrolysis is the process whereby organic and inorganic
solutes react with water resulting in degradation and transformation (Suthersan, 2002).
Calculation for the retardation coefficient, for dissolved organic constituents, is shown
below in Equation 36 (Suthersan, 2002).
                                                                      (Eqn. 36)'
where:
pb
ps
n
                       Bulk density = ps (1 -n)
                       soil density
                       porosity
                       Distribution coefficient =  Kocf0
                       Sorption coefficient
(Eqn. 37)-
                                                        (Eqn. 38)"
 Same equation used in Appendix 7 (Eqn. 21 to Eqn. 26)
                                        A8-2

-------
              foc     - fraction of total organic carbon


                      n  , ,  PsQ-^Kocfoc
                                   n
                                                                      (Eqn. 39)-
Sorption coefficients (Koc) were obtained from published values for each representative
stressor (Montgomery, 2000). For purposes of risk assessment, conservative values
(indicating the least sorption) were selected to calculate the distribution coefficient and
therefore the retardation coefficient.  Ultimately, this produces conservative estimates of
stressor concentrations at the receptors, since the data used relate to the lowest reasonably
expected retardation and the shortest travel time. The calculations incorporated a typical
value for sediment density of 2.63 g/cm (Freeze and Cherry, 1979).  Weighted mean
porosity values (Appendix 3), based on unit thickness, were used in the calculations.

Appendix Table 8-2 to 8-4 summarizes the fate and transport of the representative
stressors within 200, 500 and 2640 feet (0.5 mile) from the facility in Dade, Pinellas and
Brevard Counties.
 Same equation used in Appendix 7 (Eqn. 27)
                                       A8-3

-------
     Appendix Table 8-1.  Fate Transport (200')
Dade County




Surrogate

Chloroform (pg/L)
Tetrachloroethylene (PCE) (pg/L)
Chlordane ((ig/L)
Arsenic (mg/L)
Di(2-ethylnexyl) Phthalate (DEHP) (ng/L)
Ammonia (mg/L) (conservative behavior)
Nitrates (mg/L)(conservative behavior)

Published Half
Life in
Groundwater
(t,a) (days)
Max
1800
720
2772
N/A
389
N/A
N/A

Published
SorptJon
Coefficient

Max
1.44
2.25
4.72
2.73
4.48
0.49
N/A
Fraction of
Total
Organic
Carbon


1.76
1.76
1.76
1.76
1.76
1.76
N/A


Retardation
Coefficient
(R)
Max
1.08
1.12
1.25
1.15
1-24
1.03
N/A


Effluent Travel
Time to Receptor
Weils (te) (years)

0.11
0.11
0.11
0.11
0.11
0.11
0.11

Contaminan
t Travel
Timeftc)
(years)
Max
0
0
0
0
0
0.1
N/A


Decay
Coefficient
(k)(day-1)
Max
0.0004
0.0010
0.0003
N/A
0.0018
N/A
N/A


Concentration
at Injection Pt.
(C0)

7.18
4.66
0.010
0.010
5.00
8.75
0.64


Concentrate)
n at Supply
Wdl(C)
Min
7.06
4.46
0.01
0.010
4.57
8.75
0.64
Pinellas County



Surrogate
Chloroform (pg/L)
Tetrachloroethylene (PCE) (jig/L)
Hexachlorobenzene (pg/L)
PentacMoropheno) digit)
B«nzo(a)pyrene fjig/L)
Chlordane fyio/L)
Arsenic (mg/L)
Dl{2-ethylhexyl} Phthalate (DEHP) QigfL)
Ammonia (mgTL) (conservative behavior)
Nitrates (nig/LX conservative behavkx)
Published Half-
Life in
Groundwater
fea) (days)
1800
720
4178
1520
1060
2772
N/A
389
N/A
Published
Sorption
Coefficient

oo
Brevard County
Surrogate
Chloroform (|ig/L)
Tetrachtoroelnylene (PCE) (pg/L}
Chlordane (jig/L)
Arsenic (mg/L)
Di{2-ethylhexy1) Phthalate (DEHP) (jig/L)
Ammonia (mgfL) (conservative behavior)
Nitrates (mg/LK conservative behavior)
Published Half-
Life in
Groundwater
Oia) (fays)
1800
720
2772
N/A
389
N/A
N/A
Published
Sorption
Coefficient

2.63
2.63
2.63
2.63
2.63
2.63
N/A
Porosity (n)
0.36
0.36
0.36
0.36
0.36
0.36
N/A
Bulk Density
(Pb)
1.68
1.68
1.68
1.68
1.68
1.68
N/A
Retardation
Coefficient

1.07
1.11
1.22
1.13
1.21
1.02
N/A
Effluent Travel Time
to Receptor Wells

-------
Datte County
Surrogate
Chloroform (ug/L)
Tetrachloroethylene (PCE) (ug/L)
Chlordane (|tg/L)
Arsenic (mg/L)
Di(2-ethylhexyl) Phthalate (DEHP) (ug/L)
Ammonia (mgfL) (conservative behavior)
Nitrates (mg/L)(conservative behavior)
Published Half-
Life in
Groundwater
(t,a) (days)
1800
720
2772
N/A
389
N/A
N/A
Published
Sorption
Coefficient
(IW)
1.44
2.25
4.72
2.73
4.48
0.49
N/A
Fraction of
Total
Organic
Carbon (foc)
0.01
0.01
0.01
0.01
0.01
0.01
N/A
Distribution
Coefficient

0.014
0.023
0.047
0.027
0.045
0.005
N/A
Soil Density

1.76
1.76
1.76
1.76
1.76
1.76
N/A
Retardation
Coefficient
(R)
1.08
1.12
1.25
1.15
1.24
1.03
N/A
Effluent Travel Time
to Receptor Wells
(te) (years)
0.28
0.28
0.28
0.28
0.28
0.28
0.28
Contaminant
Travel Time
(tc) (years)
0
0
0
0
0
0.3
N/A
Decay
Coefficient

1.97
1.97
1.97
1.97
1.97
1.97
1.97
1.97
1.97
N/A

Retardation
Coefficient
(R)
1.11
1.18
1.20
1.22
1.47
1.37
1.22
1.35
1.04
N/A

Effluent Travel Time
to Receptor Wells
(tE) (years)
14.64
14.64
14.64
14.64
14.64
14.64
14.64
14.64
14.64
14.64

Contaminant
Travel Time
(tcKyears)
16.3
17.2
17.6
17.8
21.5
20.1
17.80
19.8
15.2
N/A

Decay
Coefficient
(k)(day-1)
0.0004
0.0010
0.0002
0.0005
0.0007
0.0003
N/A
0.0018
N/A
N/A

Concentration
at Injection R.
(C0)
6.70
2.50
1.74
1.28
1.82
0.640
0.003
1.25
18.00
0.28

Concentration
at Supply Well
(C)
0.68
0.01
0.60
0.07
0.01
0.10
0.003
0.00
18.00
0.28
CO
LA
Brevard County
Surrogate
Chloroform (ug/L)
Tetrachloroethylene {PCE) (ug/L)
Chlordane (ug/L)
Arsenic (mg/L)
Df(2-ethylhexyl) Phthalate (DEHP) (ug/L)
Ammonia (mg/L) (conservative behavior)
Nitrates (mg/L)(conservative behavior)
Published Half-
Life in
Groundwater
(t,a) (days)
1800
720
2772
N/A
389
N/A
N/A
Published
Sorption
Coefficient
(Koc)
1.44
2.25
4.72
2.73
4.48
0.49
N/A
Fraction of
Total
Organic
Carbon (f^)
0.01
0.01
0.01
0.01
0.01
0.01
N/A
Distribution
Coefficient
(M
0.014
0.023
0.047
0.027
0.045
0.005
N/A
Soil Density
(P,)
2.63
2.63
2.63
2.63
2.63
2.63
N/A
Porosity (n)
0.36
0.36
0.36
0.36
0.36
0.36
N/A
Bulk Density
(Pb)
1.68
1.68
1.68
1.68
1.68
1.68
N/A
Retardation
Coefficient
(R)
1.07
1.11
1.22
1.13
1.21
1.02
N/A
Effluent Travel Time
to Receptor Wells
(tE) (years)
7.58
7.58
7.58
7.58
7.58
7.58
7.58
Contaminant
Travel Time
(tc) (years)
8
8
9
9
9
8
N/A
Decay
Coefficient
(k)(day1)
0.0004
0.0010
0.0003
N/A
0.0018
N/A
N/A
Concentration
at Injection R.
(Co)
230
1.00
0.010
0.005
5.00
8.75
9.60
Concentration
at Supply Wall
(C)
73.7
0.1
0.0
0.005
0.0
8.75
9.60
       N/A = not applicable

-------
     Appendix Table 8-3.  Fate Transport (0.5 mile)
Dade County
Surrogate
Chloroform (ug/L)
Telrachloroethylene (PCE) (pg/L)
Chlordane (pg/L)
Arsenic (mg/L)
Di(2-ethyihexyi) Phthalate (DEHP) (ug/L)
Ammonia (mg/L) (conservative behavior)
Nitrates (nig/L)(conservative behavior)
Published Half-
Life in
Groundwater
(M (days)
1800
720
2772
N/A
389
N/A
N/A
Published
Sorption
Coefficient
e)tvt) Phthalate (DEHP) (ug/L)
Ammonia (mgfl.) (conservative behavior)
Nitrates (ing/LKconservative behavior}
Published Hatf-
Lifein
Groundwater
(t,a) (days)
1800
720
2772
N/A
389
N/A
N/A
Published
Sorption
Coefficient
(Koc)
1.44
2-25
472
2.73
4.48
0.49
N/A
Fraction of
Total
Organic
Carbon (U
0-01
0-01
0.01
0.01
0.01
0.01
N/A
Distribution
Coefficient
(KJ
0.014
0.023
0.047
0.027
0.045
0.005
N/A
Soil Density
fpj
2.63
2.63
2.63
2.63
2.63
2.63
N/A
Porosity (n)
0.36
0.36
0.36
0-36
0.36
0.36
N/A
Bulk Density
(Pb)
1.68
1.68
1.68
1.68
1.68
1.68
N/A
Retardation
Coefficient
(R)
1.07
1.11
122
1.13
1.21
1.02
N/A
Effluent Travel Time
to Receptor Wells
(y (years)
40.04
40.04
40.04
40.04
40.04
4004
40.04
Contaminant
Travel Time
(tc) (years)
43
44
49
45
48
41
N/A
Decay
Coefficient
(k)(day1)
0-0004
0-0010
0.0003
N/A
0-0018
N/A
N/A
Concentration
at Injection R,
(Co)
230
1.00
0.010
0.005
5.00
8.75
9.60
Concentration
at Supply Wall
(C)
0.6
0.0
0.0
0.005
0.0
8-75
9.60
     N/A = not applicable

-------

-------

-------