WASTEWATER MANAGEMENT IN COASTAL NORTH CAROLINA
The University of North Carolina at Chapel Hill
Raymond J. Nierstedt Daniel A. Okun Charles R. OIMelia Jabbar K. Sherwani
Department of Environmental Sciences and Engineering School of Public Health
Milton S. Heath, Jr. Warren Jake Wicker
Institute of Government
and
North Carolina State University
Larry D. King Department of Soil Science
December 1980
The investigation on which this publication is based was supported through The University of North Carolina Water Resources Research Institute by the Division of Environmental Management of the NC Department of Natural Resources and Community Development, and the US Environmental Protection Agency.
Project No. 50020
TABLE OF CONTENTS
Page
Abstract xii
Acknowledgments
CHAPTER I: INTRODUCTION
Options for Water Quality Management Study Areas Population Distribution and Growth Northern Area Southern Area Sewerage Computer Program Wastewater Disposal Inland Coastal Sounds Ocean Disposal Land Application Wet land Application Water Reuse Costs Interceptor Sewer System - Gravity Sewers Pump Stations Force Mains Treatment Costs Ocean Discharge Land Application
CHAPTER 11: WASTEWATER MANAGEMENT IN THE NORTHERN (DARE COUNTY) COASTAL AREA Area Description Economy and Major Employment-Generating Activities Land Use Precipitation and Flood Control Water Supply in the Northern Area Water Resources in the Northern Area Wastewater Treatment Water Quality Wastewater Flows Disposal Options Coastal Sounds Ocean Discharge Land Application for Roanoke Island Land Application on the Dare Beaches Land Application on the Dare Beaches and Roanoke Island Combined Wastewater Collection Service Areas Interceptor Sewer Plans Results Wastewater Treatment Coastal Sounds Ocean Discharge Land Application Wetland Application Re sult s Effluent Disposal Coastal Sounds Ocean Discharge Land Application Results Comparison of Options
CHAPTER 111: WASTEWATER MANAGEMENT IN THE SOUTHERN (CARTERET-ONSLOW COUNTY) COASTAL AREA
Precipitation and Flood Potential Economy and Major Employment-Generating Activities Groundwater Water Supply Wastewater Treatment Existing Quality in Area Surface Waters Water Demands and Wastewater Flows Excess Capacity Disposal Options Inland Waters Ocean Discharge Land Application Wastewater Collection Wastewater Treatment Facilities Sewerage System Plans Design Assumptions Costs of Sewerage Options Wastewater Treatment Inland Waters Ocean Discharge Land Application Costs for the Treatment Options Effluent Disposal Inland Waters Ocean Discharge Land Disposal Conclusions Inland Waters Land Application Ocean Discharge Comparison of Options CHAPTER IV: INSTITUTIONAL CONSTRAINTS AND OPTIONS
Organizational Arrangements 4-1 Cities 4-1 Counties 4-2 Interlocal Contract 4-2 Joint Management Agency 4-3 County Service District 4-4 County Water and Sewer District 4-5 Sanitary District 4-5 Water and Sewer Authority 4-6 Metropolitan Water District 4-7 Metropolitan Sewerage District 4-8 Private Water and Sewerage Companies 4-8 A Combination of Organizational Arrangements 4-9 Organizational Arrangements and Authority to Control Pollution from Nonpoint Sources 4-10 Standards for Evaluating Organizational Alternatives 4-11 Jurisdictional Adequacy and Appropriateness 4-11 Financial Capacity 4-11 Policy Making Coordination 4-11 Nonpoint Coordination 4-11 Administrative Coordination 4-12 Managerial Capacity 4-12 Democratic Accountability 4-12 Political Acceptability 4-12 Institutional Arrangements 4-12 Northern Area 4-12 Southern Area 4-17 CHAPTER V: LEGAL CONSIDERATIONS
Legal Protection of Sources of Water Supply in North Carolina Areas of Environmental Concern (AEC'S) for Public Water Supply Watersheds or Aquifers under CAMA Orders to Correct Generalized Conditions of Water Pollution Permits for Disposal of Waters into Waters Classified as a Public Water Supply Source Public Health Procedure for Protection of Public Water Supplies Septic Tank Regulation General Concepts of Coverage, Jurisdiction and Procedure Local Regulations Detailed Statutory Procedures - Ground Absorption Sewage Disposal System Act Health Services Commission Regulations Enforcement Laws and Regulations Governing the Environmental Management Commission Regulation of Land Application of Wastewaters
iii The North Carolina Coastal Area Management Act The Legislation and its Background Areas of Environmental Concern Planning under CAMA Legislation Concerning Ocean Waste Discharges Federal Legislation North Carolina Legislation Conclusions
CHAPTER VI: CONCLUSIONS
Ocean Outfalls, Evaluation of the Options Northern Area Southern Area Suggested Institutional Arrangements Legal Considerations
REFERENCES APPENDICES
(On file in the offices of the Water Resources Program Area of the Department Environmental Sciences and Engineering, School of Public Health, UNC)
North Carolina classifications for tidal salt waters and applicable water quality standards
National shellfish sanitation program manual of operation. Part 1, sanitation of shellfish growing areas
Regulation number LXXIX for the treatment and disposal of sewage in the coastal areas of North Carolina Environmental Protection Agency - protection of nations's wetlands - policy statement Environmental Protection Agency - water programs - secondary treatment information
Cost functions
Population Projection Data a) Northern Study Area b) Southern Study Area
Sewerage system alternatives for Northern Study Area
Wastewater treatment costs for Northern Study Area
Effluent discharge line and ocean outfall costs for Northern Study Area
Land application costs for Northern Study Area Total system costs for Northern Study Area
Water resources appraisal for the Northern Study Area
Sewerage system alternatives for Southern Study Area
Wastewater treatment costs for Southern Study Area
Effluent discharge line and ocean outfall costs for the Southern Study Area
Land application costs for the Southern Study Area
Total system costs for the Southern Study Area
Financial profiles of Study Areas T Detailed soil series information
U "The Use of a Digital Computer Model in Effectively Managing Ground Water Resources in Dare County, North Carolina", Elias Katz, Masters Report, Department of Environmental Sciences and Engineering, University of North Carolina at Chapel HI11, 1978.
V "Area Wide Management of Water and Sewer Services: A Case Study in Coastal North Carolina", M. T. McAdams, Masters Report, Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, 1978.
W "Technical and Economic Feasibility of Ocean Outfalls in Dare County, NC", Donald J. Spiegel, Masters Report, Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, 1978. LIST OF MAPS -Page Northern study area 1-5
Southern study area 1-6
Northern areas favorable for well field development 2-9 Water quality classification - Northern area 2-14 Effluent disposal sites - Northern area 2-16 Land application sites - Northern area 2-32 Service area boundaries - Northern area 2-42 Recommended plan - Northern Area 2-52 3-1 Existing wastewater treatment facilities - Southern Area 3-8 3-2 Water quality classifications - Southern Area 3-3 Effluent disposal sites - Southern Area
3-4 Commercial calico scallop fishing grounds, Onslow Bay, NC
3-5 Commercial shrimp fishing grounds, Onslow Bay, NC 3-6 Wastewater treatment facility locations - Southern Area 3-7 Recommended plan - Southern Area
vii
LIST OF FIGURES
Page
'Qpical computer output 1-13
Computer program 1-24
Mean annual rates of change of dune line and high water line for Northern Dare beaches and Currituck County beaches
Location of sampling stations in ocean waters offshore to proposed Dare County outfall
Land application sites and soils on Roanoke Island
Land application sites and soil series on the Outer Banks
Schematics for treatment and disposal alternatives
Overwash intensity between Cape Lookout and Cape Fear
Land application site and soils for Beaufort
Land application site and soils for Morehead City, Newport and the Morehead City/Newport Township
Land application site and soils for Newport
3-5 Land application site and soils for East and West Bogue Banks, Cape Carteret and Swansboro 3-31
3-6 Schematics for treatment and disposal alternatives 3-33
viii
--
LIST OF TABLES
Page
1-1A Population Projections - Northern Area 1-7 1-1B Population Projections - Southern Area 1-8
1-2 Sewer Pipe Sizing 1-1 1
1-3 Fecal Coliform Removal by Wastewater Treatment Systems 1-17
1-4 Hydraulic Criteria for Outfall Pipe and Diffuser 1-19
1-5 Water Budget for Lynchburg Sandy Loam in Morehead City Area, 1953 1-26
1-6 Heavy Metal Loading Rates 1-28
1-7 Effect of Pretreatment on Pathogen Survival and the Infective Dosage of Pathogens 1-29
1-8 Estimated Quantity of Nitrate-Nitrogen Which Would Enter the Ground Water Below the Roanoke Island Sites 1-32
1-9 Gravity Sewers, Force Mains and Pump Stations 1-36
1-10 Cost Functions for Treatment from EPA (1975) 1-38
Package Plant Cost Function 1-39
Recommended Recession Lines for Dare County Complex Barrier Beach Island 2-6
Northern Area Water Demands 2-12
Northern Area Wastewater Flows 2-13 Ocean Depth as a Function of Distance from Shore for the Proposed Dare County Outfall 2-15 Water Quality Data from Atlantic Ocean Waters Offshore to Dare County 2-18 Effectiveness of Treatment and Ocean Disposal Alternatives for Dare County Area 2-23 Costs of Treatment and Ocean Disposal Alternatives for Dare County Area 2-24 -Page Wastewater Characteristics for Roanoke Island 2-25 Industrial Wastewater Flow and Characteristics - Wanchese Harbor Project 2-26 Estimated Wastewater Characteristics for Dare County Study Area 2-30
Northern Area Interceptor System Costs 2-44
Northern Area Treatment Costs 2-47
Effluent Disposal Costs 2-49
Total Costs of Alternatives 2-51
Effects of Tropical Storms on Bogue Banks, North Carolina 3-4
Southern Area Water Demands 3-12
Southern Area Wastewater Flows 3-13
Ocean Depth as a Function of Distance from Shore for the Proposed Bogue Banks Outfall 3-17
Treatment and Ocean Disposal Alternatives 3-21
Costs of Treatment and Ocean Disposal Alternatives for the Carteret-Onslow County Area 3-22
Wastewater Characteristics for Beaufort 3-24
Wastewater Characteristics for Morehead City, Newport, and Morehead City/Newport Township 3-26
Wastewater Characteristics for East Bogue Bank, West Bogue Bank, Cape Carteret and Swansboro 3-30
3-10 Peaking Factors for Interceptor Sewers
3-11 Southern Area Interceptor Sewer Costs
3-12 Wastewater Treatment Requirements
3-13 Southern Area Treatment Costs
3-14 Southern Area Effluent Disposal Costs
3-15 Total Costs of Alternatives
3-16 Breakdown of Costs for Plan 55B
X -Page 4-1 Number of Water and Sewer Customers of Local Governments in Dare County, July 1, 1977 4-13
4-2 Assessed Valuations, Tax Rates, Debt and Debt Ratios for Local Governments in Dare County, 1977 and 1978 4-14
4-3 Number of Water and Sewer Customers of Local Governments in Carteret County and Swansboro, July 1, 1977 4-15
4-4 Assessed Valuations, Tax Rates, Debt and Debt Ratios for Carteret County Local Governments and Swansboro, 1977 and 1978 4-16
6-1 Summary of Dare County Wastewater Disposal Options 6-5
6-2 Comparison of Dare County Options 6-5
6-3 Summary of Carteret County Area Wastewater Disposal Options 6-7
6-4 Comparison of Carteret County Options 6-8
ABSTRACT
Rapid growth and development, particularly for tourism and second homes,
in coastal North Carolina have already done serious damage to the aquatic
environment. High-density residential and hotel developments, with inadequate
facilities for wastewater collection and disposal, have resulted in a
proliferation of septic tanks and other inadequate treatment units. Local
groundwater supplies have been contaminated. Economically and recreationally
important shellfish growing areas in inland coastal waters have been badly
polluted to the point that extensive productive beds have been closed. Unless
sound wastewater management practices are introduced, the threat to the public
health and despoilation of additional shellfish areas can be expected to
continue. Increased development will exacerbate the problems.
In order to assess the options for sound wastewater management in coastal
North Carolina, two areas are selected for study: the Dare County area in the
north, and the Carteret County area (with a small portion of Onslow County) in
the south.
Three options for wastewater management are examined, all based on
sewerage of developed areas, with treatment appropriate to the method of
disposal:
1. Discharge to inland coastal waters;
2. Discharge to the ocean; and
3. Disposal on the land.
Wastewater reuse is discarded as an option because water supply resources are
found to be ample in the study area. Disposal on wetlands is also not
xii evaluated in detail because of uncertainties over allowable loadings, and its clearly high cost in the areas under study.
Facilities on which cost estimates are based are for populations expected in the year 2000. The specific costs for the options considered are not intended to be precise, but are sufficiently reliable to permit comparisons among the options.
Conclusions
Ocean outfalls exhibit considerable economies of scale. In order to be economically feasible, an ocean outfall must serve a substantial population.
In the coastal areas of NC, where populations are sparse, this requires exten- sive sewerage systems and transmission mains to conduct the wastewater over considerable distance to a point of discharge. Despite the high cost of sew- erage for the ocean disposal option, this option is no more expensive and generally less costly than the other options. Ocean disposal for the northern area can conveniently and economically serve the entire population. In the southern area, the mainland communities are so located that the most economi- cal solution there is a combination of an ocean outfall with land disposal for the inland communities. (The recommended plans are illustrated on Maps 2-6
(page 2-52) and 3-7 (page 3-64).) Not only would disposal to inland waters be more costly than ocean disposal, principally because of the extensive treat- ment required prior to discharge to these sensitive waters, but disposal to inland waters will always pose a threat to shellfish growing areas, and there- fore would be the least desirable option from an environmental standpoint.
In considering ocean outfalls, adequate data off the NC coast that permit precise estimates of the drift of wastewaters with the currents and the
xiii dispersion of wastewaters in these offshore waters are not available. It is necessary to be extremely conservative in selecting the length of the outfalls and the depth at which the outfall diffusers must be placed. Four options are considered for the selection of the ocean outfalls: primary sedimentation, with and without chlorination, and secondary treatment, with and without chlorination. The primary objective in the design of an ocean outfall is to protect the bathing beaches for swimming. Higher quality effluents permit shorter, shallower outfalls. The lowest cost among these four options for maintaining bathing water quality on the beaches is found to be primary sedimentation and chlorination. While anything less than secondary treatment had been proscribed, a relaxation of this requirement for ocean disposal has already been promulgated.
Inasmuch as ocean outfalls are only economical if they serve substantial populations (which means in NC coastal areas that they serve large areas encompassing many separate political entities), the study includes an assessment of institutional options available for implementing regional wastewater collection and disposal systems. The organizational structure suggested would place primary responsibility for sewerage and water pollution control services in the county governments in each of the study areas.
The principal legal issue to be resolved is authorization for ocean outfalls in North Carolina in the first place and federal constraints on ocean discharge with only primary treatment.
The Coastal Area Management Act provides a setting for orderly land development so that the provision of sewerage system in the coastal area need not stimulate unwanted growth.
xiv
ACKNOWLEDGMENTS
Among the authors listed on the title page, Dr. Charles R. OfMelia was responsible for the ocean outfall assessments; Dr. Jabbar K. Sherwani for groundwater evaluation; Prof. Milton S. Heath, Jr. for legal issues; Prof.
Warren Jake Wicker for institutional questions; and Dr. Larry D. King for study of the land disposal of wastewaters.
In addition to the authors, the following graduate students in the
Department of Environmental Sciences and Engineering contributed significantly to this project: Elias Katz - Dare County groundwater assessment M. T. McAdams - Institutional arrangements in Dare County Donald J. Spiegel - Ocean outfall analysis and design Jeffrey G. Wendle - Data collection and analysis Parts of the work done on this study were incorporated into project reports used to satisfy in part requirements for the Master of Science in
Environmental Engineering degrees for Messrs. Katz, Spiegel and Nierstedt; and for the Master of Science in Public Health degree for Mr. McAdams.
The authors are grateful to the staff of Henry von Oesen and Associates, consulting engineers and planners of Wilmington, NC, for making available much of the basic data required for this study. Thanks are also owed to the staff of the Division of Environmental Management of the NC Department of Natural
Resources and Community Development, and to the personnel of local governments in Dare, Carteret, and Onslow Counties.
Raymond J. Nierstedt
Daniel A. Okun
Chapter I
INTRODUCTION
The purpose of this study is to evaluate the options for water management in coastal North Carolina. This study focuses on two areas on the coast of North Carolina as exemplary of the problems of, and possible solutions for, the entire coastal region: the Northern Area, comprising Dare County, and the Southern Area, centering on Carteret County. These areas, as is the entire coastal area of North Carolina, are growing rapidly. The gravity of the problem that such growth imposes has been well stated:
Among the most valuable resources of the Southern United States are its coastal lands and waters. The coastal area, and in particular--the estuaries--are among the most biologically productive regions of the nation, spawning major sports and commercial fisheries. The extremely high recreational and aesthetic values of coastal lands and waters carry the seeds of their own destruction through their attractiveness for economic development.
In recent years, these areas and their fragile ecosytems have been threatened with increasing pressures for development. Unless these pressures are controlled and directed in a conscientious way, the very features of the coast that make it economically, aesthetically, and ecologically rich will be damaged--even destroyed. A major problem associated with increase in population growth and economic development in these areas is the provision of safe and adequate water supplies and the management of wastewater discharges in a manner consistent with public health and welfare and environmental protection. *
Unfortunately, even a "no growth" posture would not alleviate the problems. Relatively uncontrolled development has already affected the coastal areas most deleteriously. Inadequate wastewater disposal has fouled water supplies and recreational and commercial coastal waters, endangering the health of the permanent and vacationing populations, and closing extensive shellfish beds, and threatening the reproductive cycle of fin fish. The Dare County 201 Study (Von Oesen, 1976) speaks eloquently to the economic impact of the erection of the range signs designating an area as off-limits for shellfishing.
This study was mounted on the assumption that such pollution should be abated to promote environmental quality, including the protection of public health, to restore the important shellfish growing areas that constitute an important North Carolina resource, and to maintain fish productivity.
*~roman excellent resume of the coastal water situation in the Proceedings of the Southeastern Conference on Water Supply -and Wastewater -in Coastal Areas, published by the UNC WRRI in 19r Any solution to the current problems of pollutiaIn in the coast a1 areas will ---if no other measures --are taken, encourage further growth in the coastal areas. Many environmentalists and preservationists oppose some of the solutions considered in this study, not because the solutions are inherently wrong, but solely because -any solution to the water pollution problem would appear to permit and encourage further growth. This report is written on the assumption that present problems need to be addressed and control of growth on the coast, if this is perceived as being desirable, should not be exercised by failure to provide necessary pollution control facilities.
The coastal areas of North Carolina constitute a great state and national resource. However, increasing pressure from urban populations will be exerted on coastal North Carolina in the future because of already heavy development of coastal areas in the north, greater leisure and the desire for second homes and retirement homes, and the economic attractiveness of vacationing in the United States, as contrasted with foreign travel, because of the fall of the dollar and increased travel costs attributable to rising energy prices.
These increased pressures of development in coastal North Carolina have had deleterious consequences as important as water pollution, consequences which may ultimately destroy the area as an amenity. The fragility of the beaches is well documented by Kaufman and Pilkey (1979) who describe the futility of our efforts to maintain the physical integrity of the barrier islands despite massive investments.
Nothing in this report should be construed as promoting development in the coastal areas and particularly on the barrier islands. The options for abating pollution in an economical and environmentally sound manner are intended to address the probiems created by development that has already taken place and such additional development as is perceived by planners in the areas to be acceptable. These options, for wastewater management, if any are adopted, are not intended to give license to planners and developers to accelerate development or to increase the level of development beyond that which is otherwise sound.
Options for Water Quality Management
It is possible to continue with present wastewater management practices which involve small and large septic tanks, with subsurface disposal of the effluents, and package plants for larger installations such as motels. These facilities have resulted in pollution of groundwaters and surface waters. Studies of improved methods of wastewater disposal for individual homes are being made (Carlile, Osborne, 1978) but have not been tested on a large scale or in the long term. For the purposes of this study, such individual on-site systems are not considered amongst the options for the region. However, they might well be considered for appropriate areas in the future. Were individual on-site systems to be adopted in sparsely settled areas they would not have significant impact on the regional solution. Current population pressures and the modest growth to be expected in the future call for wastewater management systems except, perhaps, in the more isolated areas. The options considered in this study include sewerage, wastewater treatment, and disposal either to the land, to inland waters, or to the ocean, or a combination of these. Because water supplies in the study areas were found to be ample, reuse was not evaluated.
This report considers each of the three options, disposal to land, to inland waters, and to the ocean, in detail to ascertain relative costs. No distinction is made in the comparison of costs between capital costs to be met by federal and state construction grants and those to be provided by the local communities. It is assumed that these are total societal dollar costs. Of course, where an option exhibits relatively higher capital costs and lower operation and maintenance (O&M) costs, that option will be favored by the availability of construction grants.
The study goes on to consider legal and institutional constraints to the adoption of these options together with the institutional requirements necessary to implement the most desirable option.
Ancillary studies executed in connection with the preparation of this report, such as that evaluating water supply resources in the study areas, are included in appendices which are not reproduced in the report but are on file in the offices of the Water Resources Program Area of the Department of Environmental Sciences and Engineering, School and Public Health of the University of North Carolina at Chapel Hill.
Study Areas
The two areas were selected for detailed study as being representative of coastal North Carolina. The Wilmington area is substantially different, but as wastewater disposal decisions for the Wilmington area have only recently been made and are now being implemented, this area was not included for study.
Maps 1-1 and 1-2 show the study areas. The Northern Area includes most of Dare County while the Southern Area includes most of Carteret County and a small part of Onslow County. The Dare Beaches and the Bogue Banks beaches constitute rapidly growing recreational and resort areas. Population pressures on these beaches have created much of the pollution problem which this study addresses. However, the mainland communities are polluting the inland waters as well. A sound solution must consider the Outer Banks and the mainland together.
Population Distribution and Growth
The purpose of this study is to evaluate options for wastewater management; not to prepare engineering reports upon which specific projects might be based. Accordingly, population data and growth projections used in this study are based upon estimates made for agencies in the study areas by consultants and others. These are not assumed to be the most precise data that can be assembled, but precision in population forecasting is elusive at best. However, the data do provide a basis upon which the several options for wastewater managment in the study areas can be evaluated. The population estimates are believed to be reasonable, so that the relative costs of the several options are not affected. The conclusions drawn are taken as being independent of the accuracy of the population estimates.
Coastal North Carolina is an important tourist and resort area. Pollution estimates are complicated by large seasonal variations. The coastal area is served by a relatively small permanent population which is resident throughout the year. Summer residents, tourists and day visitors increase the population several-fold during June, July and August. The summer peaks are much more marked on the Outer Banks than on the mainland. Accordingly, the ratio of transient to permanent population is much greater in the Northern area, which is dominated by the Dare beaches. The Southern Area, with its several mainland communities, including Beaufort, Morehead City, and Newport, suffers less from seasonal variations than the Northern Area. Tables 1-1A and 1-1B summarize the population estimates that are the basis of this study, namely, populations to be served by wastewater collection and disposal facilities. Detailed population data, from 201 facilities planning studies, are used in sewerage system layouts in this study, but are not elaborated in this report.
Population estimates are made for 1980, 1990 and 2000, with the new facilities capabilities being based on a 20-year design period.
Northern Area
The people to be served in the Northern Area include only those who are expected to live in population centers that can reasonably be expected to be served by sewers. Thus, Southern Shores and Duck, because they are scheduled for low density development, are not easily served by sewers (Wendle, 1977).
The most comprehensive study for the Northern Area was made by Stephens Associates (1973) for Dare County as a whole. Currently 63% of the Dare County permanent population resides in the study area, and the study assumes that, in the future, 64% of the population will reside in the study area. It is further assumed that 80% of the seasonal residents in the county will be in the study area and that 50% of the day visitors will visit the study area, with 90% of these visiting the beach areas.
The population estimates for Manteo and Wanchese are based on the land-use plan (N.C.D.N.R.C.D., 1974), which calls for densities of 5 and 12 per acre, respectively. In 1970 and 1974, Manteo accounted for 12% and Wanchese 4.5% of the population in the study area and these figures are assumed for the future. Allowance is made for some 640 new jobs in fish processing in Wanchese, accounting for an increase of about 1600 population in the next decade. Peak populations are based on estimates for the Dare County 201 Facilities Plan, with the assumption that there will be no day visitors in Manteo and no seasonal influx in Wanchese. Map 1-1 NORTHERN STUDY AREA -Water Management in Coastal North Carolina -Dare County, 1979 Study Area Boundary
ATLANTIC OCEAN CRAVEN COUNTY ------
ATLANT/C OCEAN
SOUTHERN STUDY AREA Map 1-2 -Water Managenent in ----Study Area Boundary Line Coastal North Carolina -201 Study Area Dividing Line SCALE fN fdvtiLES Source: Von Oesen 1975, 1977 pxw 01234 Table 1-1A. Population Projections--Northern Area
Dare ~eaches* Permanent Residents Seasonal Residents Seasonal Residents
TOTAL 32000 40000 54000 75000
Manteo Permanent Residents Seasonal Residents
TOTAL 2900 3500 4500 5900
Wanchese Permanent Residents
Totals, Northern Area Permanent Residents 2 900 4500 9000 12000 Seasonal Residents 27000 32000 42000 5 7000 Day Visitors 5000 7500 10000 15000
TOTAL 35000 44000 6 1000 84000
a are Beaches include Kill Devil Hills, Nags Head and Whale Bone Junction Nagshead = 36% of area population Kill Devil Hills = 51% of area population Whalebone Junction = 13% of area population Table 1-1B. Population Projections--Southern Area
Beauf ort Permanent Residents Seasonal Residents
TOTAL
East Bogue Banks Permanent Residents Seasonal Residents
TOTAL
Morehead City Permanent Residents
Newport Permanent Residents
Morehead Ci t y/Newport Twp Permanent Residents
Swansboro Permanent Residents
Cape Carteret Permanent Residents
West Bogue Banks Permanent Residents Seasonal Residents
TOTAL
Totals Southern Area Permanent Residents Seasonal Residents
TOTAL The Dare Beaches have 13.7 sq. miles of land designated for populations exceeding 2000 per sq. mi (3.1 per acre), For the purpose of this report, maximum density of 10,800 per sq. mi is assumed, resulting in an ultimate population of about 150,000, half to be reached by 2000.
Southern Area
The basic data for the Southern Area were largely obtained from the Henry Von Oesen Carteret County and Swansboro 201 Studies. The plan assumes that the ultimate population will be reached in 2000-2005, and that the peak population in the Bogue Banks will be 400% of the permanent population. The population is based upon zoning and land use plans, with 2 to 3.5 persons per unit, depending upon the type of housing, and a maximum density of 10 units per acre; which corresponds to some local ordinances.
Except for Beaufort, with a small summer population increase, the other mainland communities are assumed to undergo no seasonal changes in population.
Sewerage
The sewerage systems in the study are combinations of interceptor sewers and pump station-force main systems, with subaqueous mains as needed. In flat terrain, the interceptor sewer includes a series of lift stations and gravity sewer lines. A force main is utilized to transport wastewater flows through areas where no wastewater collection service is to be provided.
As a sewerage system in flat terrain may be 10 to 15 feet deep, it is susceptible to problems of ground water intrusion because of the high water table. This problem does not apply to force mains, as they are usually about four feet deep and under pressure. The depths of the pump stations in such cases require that precautions against floating be taken.
When an interceptor sewer is utilized in applications in this study, two assumptions are made: 1) the areas serviced are flat; and 2) the population is distributed over the area in such a manner that the tributary load to the sewer is uniform. The criteria used for sizing the systems are listed below, followed by the basis for selecting the criteria:
Pipes flow full at peak flow. Minimum velocity in pipe flowing full is 2 ftlsec. Cover over pipe is at least 2 ft. Minimum invert depth is 4 ft. Maximum invert depth is 12 ft. Manning roughness coefficient is 0.014. Total head at each lift station is 15 ft. Minimum velocity in force mains is 4 ftlsec. The dimensioning of pipes flowing full at peak flows is justified because of the vast differences in the summer and winter flows. An important consideration in a long flat system is corrosion of the pipe crown by sulfuric acid, formed from hydrogen sulfide produced naturally in a sewerage system in warm weather. A second consideration is infiltration. Proper selection of pipe material and joint construction should help alleviate both problems.
The allowable vertical drop in a sewer run is constrained by requirements of invert depths of 4 and 12 ft. For pipe diameters of 24 in or less, the 2- ft cover requirement can be met by placing the invert at the minimum depth of 4 ft, and an 8 ft vertical drop is available. For pipe diameters larger than 24 in, the pipe invert at the upper end of the system must be lower than 4 ft, reducing the vertical drop to less than 8 ft. The resulting vertical depths, slopes and length of pipe shown in Table 1-2.
Each time an interceptor segment reaches a depth of 12 ft, a lift station is required. As each lift station works against the same head, a static lift of 12 ft (4 ft wet well and 8 ft vertical rise) and a friction loss of about 3 ft, or a total head of 15 feet, is used.
Force mains and subaqueous sections are required for pipelines crossing the sounds. Head losses in the force mains are determined by the Hazen-Williams equation with a coefficient of roughness value of 100.
Computer Program
A computer program was utilized to do the layout of the sewerage system. It begins at a known low point in the system, such as a wastewater treatment facility or a manhole. The program assumes there is a wet well at that point and the pipe invert is 12 ft deep. A length of pipe to feed that point is known as are the winter and summer flows. It puts a peaking factor on the flow, fits it to a pipe size and gives the length of run available for the appropriate vertical rise. At the end of this pipe length a lift station is required. A flow/ft ratio is multiplied by the pipe length and this flow is subtracted from the original flow to give a flow for sizing the pump. This new flow value is used to size the next pipe section. As the program rarely ends with the "length left" value equal to a pipe length for an available vertical drop (generally 8 ft), the output writes "Problem" and gives the calculated vertical drop. (See Fig. 1-1.) The computer program is shown in Fig. 1-2.
The program accepts a length and a flow and can then break this length into discrete sections of pipeline and lift stations. As the program begins at a known point, the flow that is input represents the projected wastewater flows for the towns along the interceptor. In cases where only one town is involved, the treatment facility is considered to have two inputs, one from each end of town. The flow that is transported by each pipe input is approximated, and this approximation is held constant each time this breakdown is needed. Table 1-2. Sewer Pipe Sizing
Manning Equation:
V = Velocity, 2 ft/sec d = diameter, feet N = roughness coeff. = 0.014 S = slope of energy line, ft/ft r = hydraulic radius, feet Q = flow, cfs
Available d (in) Vertical Drop Length (ft) (ft)
Force and Subaqueous Mains
Diameter (inches) Flow (cfs) Wastewater Disposal
The goal of selecting a system for wastewater disposal is to minimize, or even avoid if possible, any adverse impact on the ecosystem. Each disposal site has a specific capacity to assimilate a quantity of wastewater of a certain quality. Some sites may require more extensive or different treatment processes than others. State and federal laws and regulations govern discharges to the rivers and ocean, while local, particularly coastal zone, regulations may cover land application. However, where such laws and regulations are believed to impose unreasonable and uneconomic constraints, in this report the solutions are approached with an understanding that these laws and regulations may be modified. Just such a change in the Water Pollution Control Act Amendments of 1972, PL 92-500 was effected by the Clean Water Act of 1977 (PL95-217) to enlarge ocean discharge options. Such studies as this may, in fact, help initiate such changes.
Inland Coastal Sounds
All of the coastal surface water bodies studied in this report are capable of supporting shellfish. However, many of these shellfish growing areas in inland waters are being closed because of high coPiform levels, resulting from effluents of faulty septic tank sytems which leach into surface water bodies, and from inadequately treated wastewater being added directly to the water bodies,
Septic tank system failures result from high water table, poor soils, overloaded tanks, or clogged filter fields. However, problems also occur from properly operating septic tank systems which are located in densely populated areas. Septic tank systems are not appropriate for high housing densities, because of the need for large leaching areas for nitrification fields. The NC Coastal Zone Regulations 2-79 state that "Septic tanks will not be approved for areas having more than three residential units per acre." The impact of high-density housing utilizing septic tanks was demonstrated dramatically in a recent test on East Bogue Banks at Atlantic Beach. Dye appeared in Bogue Sound only about four hours after being flushed down a toilet in a house on the island adjacent to the sound (Von Oesen, 1977).
As shellfish are filter feeders, they are able to magnify the concentration of coliform or other substances to levels exceeding the surrounding waters. Thus even treating wastewater to reach the 70/100 ml coliform standard in shellfish waters imposed by the US Public Health Service may not insure adequate quality of the shellfish because the shellfish can magnify this concentration. Shellfish production is just not compatible with wastewater disposal to the waters in which they grow.
Each of the surface water bodies has been classified either to protect shellfish beds, to provide recreation and swimming, or to receive wastewater. The higher use also permits the lower use. Each of these categories contains specific requirements for the wastewater that can be assimilated. "SAW waters refer to saline waters used to breed shellfish for marketing purposes. "SB"
waters refer to those open for bathing and recreation, but no shellfish actlvities, and "SC" waters refer to "swamp" water, where swimming, shellfishing and recreation are not permitted. Sound resource management aims at providing the greatest possible number of uses by the greatest possible number of users.
The Division of Environmental Management has classified all segments of waterways in the state into two general categories (1) effluent limited, and (2) water quality limited. Effluent limited segments are those where water quality standards in receiving waters can be achieved with secondary treatment of wastewaters. Discharges into segments that are water quality limited must have advanced wastewater treatment beyond secondary treatment. In coastal areas, ocean waters are "effluent limited" and inland waters are generally "water quality limited."
The state Environmental Management Commission has issued a policy statement on the treatment and disposal of wastewaters in coastal areas of North Carolina in the form of Regulation 2-79. These criteria are particularly pertinent to water quality objectives:
No wastewater will be discharged into water classified "SA" for the taking of shellfish for market purposes nor to waters in such close proximity as to adversely affect such waters regardless of treatment proposed. Wastes discharged into waters tributary to waters classified "SA" shall be treated in such manner as to assure that no impairment of water quality in the "SAW segments will occur.
No wastewaters will be discharged to waters classified "SB" unless these wastewaters are treated to the extent necessary to assure protection of assigned water quality standards.
No discharge shall be allowed to any surface waters that experience excessive growths of microscopic or macroscopic vegetation or that, because of their relative size and lack of water exchange, are found by the Board to be subject to such excessive growths.
These conditions prohibit wastewater discharges to "SAW waters and regulate discharges to "SB" and "SC" waters,
The surface water bodies and the inlets to the ocean all work together as a complex estuarine system. The system is affected by winds and tides. Discharge of effluent to an inlet does not necessarily mean that it will flow directly to the ocean. Many of the existing water quality infringements result from the fact that the incoming tides carry wastewater effluents upstream rather than downstream. Thus, discharges to inland coastal waters require extensive wastewater treatment.
Ocean Disposal
An ocean disposal system as considered here consists of a wastewater treatment facility, a subaqueous outfall pipe with a diffuser, and the marine environment itself. These three components of the system are described below, together with the criteria used and assumptions made for the ocean disposal plans presented in this report.
Wastewater Treatment Alternatives. Four treatment alternatives are considered for use in combination with ocean outfall pipe and diffuser facilities to provide wastewater disposal to the ocean. These are: (1) primary treatment alone, (2) primary treatment with chlorination, (3) secondary treatment alone, and (4) secondary treatment with chlorination.
The effectiveness of the treatment processes used in these treatment systems is as follows:
Primary treatment removes settleable solids and floatable materials.
Secondary treatment removes most nonsettleable suspended solids and biodegradable dissolved organic substances.
Chlorination kills substantial numbers of microorganisms.
Both primary and secondary treatment produce waste solids that require ' disposal. Anaerobic digestion is widely adopted to render these sludges more easily manageable, meanwhile producing a humus-like material suitable for disposal on land. Anaerobic digestion and land disposal of sludge are used for estimates in this study.
These four alternatives are ordered above in terms of increasing treatment efficiency and increasing treatment facility cost. Primary treatment used alone provides the lowest degree of treatment with the lowest costs for treatment and sludge disposal, while requiring the longest and most expensive outfall for acceptable discharge of effluent to the ocean. Among the four treatment options, secondary treatment with chlorination provides the highest degree of wastewater treatment with the most expensive treatment and sludge disposal while permitting the shortest and least costly outfall for ocean discharge. The ocean outfall systems presented in this report have been designed to protect the quality of the bathing waters at North Carolina beaches. In doing so, the effectiveness of each treatment option for removing fecal coliforms has been assessed (Spiegel, 1978). Results are presented in Table 1-3. A fecal coliform concentration of 1 x lo8 per 100 ml is assumed for untreated domestic wastewater. Table 1-3. Fecal Coliform Removal by Wastewater Treatment Systems
Effluent Fecal Removal Colif orms Treatment System (per cent) (per 100 ml) Primary Treatment Alone
Primary 20-50 by primary, Treatment with 90-99 by disinfection Disinfection overall, 92 to 99.5%
Secondary 20-50 by primary, 5 X lo5 Treatment 90-99 by biological to Alone overall, 92 to 99.5% 8 X lo6
Secondary 20-50 by primary 5 x 103 Treatment 90-99 by biological, to with Disinfection 90-99 by disinfection, 8 X 105 overall, 99.2 to 99.995%
Note: Influent fecal coliform count assumed to be 1 X lo8 per 100 ml.
The Marine Environment. Evaluation of the environmental effects of ocean outfalls systems can include bacteriological, physical, chemical, biological, and toxicological characteristics of the wastewater, the receiving waters, and the bottom sediments.
Bacteriological criteria are used to prevent transmission of disease in the recreational uses of the water or by ingestion of contaminated shellfish. Recreational water use is extensive in the coastal ocean waters of North Carolina, while commercial harvesting of oysters and clams in ocean waters is sparse. Such shellfish grow and are harvested primarily in inland coastal waters. For bathing, defined as Class SB waters, the State requires that fecal coliform concentrations not exceed a log mean of 200/100 ml for any 30-day period from May through September. The treatment and ocean outfall systems presented in this report have been designed to meet this objective.
Pertinent physical parameters for characterizing receiving waters include floatable solids, oil and grease, suspended solids, turbidity, color, and temperature. Minimal treatment and disposal systems can prevent serious physical problems in ocean waters. Experience with other outfall systems indicates that organic deposits may develop in the immediate area of the ocean discharge. Major chemical constituents of concern include biochemical oxygen demand (BOD), dissolved oxygen (DO), and inorganic nutrients (nitrogen and phosphorus). Water quality standards for these parameters in ocean waters have not been established. Treatment and disposal techniques combined with natural processes and ample dissolved oxygen resources prevent problems. Nutrient additions are relatively small, and increases in ambient levels are difficult to detect,
Experiences with existing ocean outfall systems have identified effects on marine biota in receiving waters and sediments. In general, effects on pelagic species due to domestic wastewater discharges have been small. Effects in sediments are confined to the outfall region and indicate an increase in productivity (biomass) accompanied by a decrease in diversity (number of species).
The discharge of toxic substances to all environments, including the ocean, must be strictly controlled. Principal emphasis is properly placed on synthetic, toxic, persistent organic substances such as DDT and the PCBs. Similarly, discharges of toxic metals such as copper, cadmium, and lead must be prevented. The diposal of toxic organics and metals and can be managed by control at their principal source, i.e., industrial wastewater discharges to municipal sewer systems. It is anticipated that this will not be a problem in the coastal regions of North Carolina studied in this report because of the paucity of industry.
Outfall Pipe and Diffuser. The outfall pipe is used to transport the wastewater to a suitable location in the ocean for disposal. A specially designed diffuser is placed at the end of the outfall pipe to provide mixing between the wastewater and seawater. The diffuser contains a number of holes or ports along its length, each discharging a small portion of the total wastewater discharge to the ocean. The buoyancy force originating from the lower density of wastewater and its kinetic energy as it is jetted through the ports are dissipated in the ocean, causing extensive mixing and dilution. In practice, outfall and diffusers are designed to achieve a dilution of about 100 to 1 with sea water.
Hydraulic requirements of the diffuser and the outfall pipe are presented in Table 1-4. These are selected to maintain pipe and diffuser efficiency and to lower maintenance costs.
An analysis of the costs of constructing ocean outfalls was made to permit prediction of the costs of outfalls in the study areas. Based on work by Pearce (1977), data from 33 outfalls constructed in the United States during the past 30 years were analyzed using five different models for cost functions. The available data do not permit separate analysis of the costs of the outfall pipe and the diffuser; total costs were considered. The costs of each outfall were adjusted to July 1, 1977 dollars using Engineering News Record construction cost indices. The cost function selected is as follows (Spiegel, 1978): Table 1-4. Hydraulic Criteria for Outfall Pipe and Diffuser
Design Parmeters Criteria Basis
Port Flow Equal distribution from Uniform dilution with sea all ports water Port Velocity <20 fps, but > ocean Prevent scour of port current
Port Diameter 1/10 to 114 pipe Provide flow distribution, diameter, >2 inches prevent plugging
Aggregate Port 113 to 2/3 outfall Provide flow distribution Area cross-sectional area
Pipe Velocity 2 to 3 fps for primary Present solids deposition in effluent; 0.5 to 1 fps pipe for secondary effluent
Head Loss Hazen-Williams equation, in Pipe C = 120
Here, C/L is the cost of an outfall in 1977 dollars per linear foot and D is the pipe diameter in inches.
Modeling Coliform Concentration. Concentrations of fecal coliform in raw domestic wastewater are reduced by four processes to protect bathing areas through ocean disposal. First, wastewater treatment reduces fecal coliform concentrations substantially, as noted previously. Second, the hydraulic diffuser at the point of ocean discharge provides substantial reduction by dilution. ~hird,additional mixing with ocean water occurs by eddy diffusion as the diluted wastewater plume is carried away from the outfall region by ocean currents. Finally, coliforms die by natural processes in sea water.
Assumptions made regarding the destruction of fecal coliforms by wastewater treatment are presented in Table 1-3. In this work, the maximum estimated effluent concentration from a treatment system has been assumed to reach the diffuser. For example, the fecal coliform concentration after primary treatment and disinfection is assumed to be 8 X 106 per 100ml.
The dilution accomplished by the diffuser depends on the location (depth) of the discharge, the diffuser itself, and ocean conditions. Certain ocean conditions are assumed for all cases examined in this report: ocean water density is assumed to be 1.026 gm/cm3. Under these conditions, initial wastewater dilutions at the outfall are in the order of 100 to 1,
Dilution by eddy diffusion as the wastewater plume is carried from the outfall site by ocean currents has been modeled using Richardson's 413 power law for the diffusion coefficient, E. Specifically, it has been assumed that E = a~~/~,where E is in cm2/s, a is a coefficient equal to 0.01 (cml2l3, and L is the width of the wastewater field in the ocean. (Pearson, 1956; Yudelson, 1967). The size (width) of the field increases as it is carried from the outfall site, so that dilution by eddy diffusion also increases with distance traveled. Locating an outfall a long distance from shore increases the dilution provided by diffusion when onshore currents push the wastewater field toward the shoreline.
The rate of dieoff of fecal coliforms is described in this work by a coefficient, tgo, that is the time to reduce the fecal coliform concentration in the ocean by 90% due to dieoff alone. For this work, tgo is taken as 9 hrs (Spiegel, 1978).
In considering dilution by eddy diffusion and dieoff in the ocean, the diffuser is assumed to be parallel to the shoreline, or perpendicular to the onshore currents. A current velocity of 7 cm/s is assumed in transporting the wastewater field toward the shore.
As stated previously, the treatment and ocean disposal systems presented in this report are designed to meet present bathing water quality standards in North Carolina. It is expected that these systems will provide wastewater disposal without significant adverse physical, chemical, or biological effects in the receiving waters. This requires that any significant quantities of toxic substances produced or used within the tributary area of the sewerage system be disposed of without recourse to the sewerage system.
Important assumptions made in the analysis include the following: 1. The coliform concentrations in the effluent from the treatment system of interest: the highest estimate made for each combination of treatment and disinfection is assumed, as shown in Table 1-3.
2. The direction, duration, and velocity of the ocean current: a velocity of 7 cm/s, directed onshore, and persisting long enough to carry diluted wastewater effluent to beach areas.
3. The dieoff rate coefficient for the coliform organisms in ocean waters: tgo value of 9 hours.
The overall effects of these assumptions on the ocean outfall systems designs are considered to be conservative.
Analyses for the Dare County area (Spiegel, 1978) indicate that, of the four ocean outfall options evaluated, primary treatment and disinfection coupled with an ocean outfall and diffuser provide the least cost system. Hence, primary treatment and disinfection are used in all comparisons of ocean discharge with other disposal alternatives.
The ocean outfalls considered have depths at their points of discharge that vary from about 50 to 75 feet, depending primarily on the length of outfall. Systems for treated wastewaters have emphasized the importance of providing ocean depths of 200 feet or more. This consideration is based on practice on the west coast of the United States, where the steep slope of the continental shelf provides large depths for such outfalls. Nevertheless, the environmental conditions produced by the outfalls considered in this report are expected to be equivalent to successful west coast experience.
While this study was in progress, a separate study evaluating "Ocean Outfall Wastewater Disposal Feasibility and Planning" for coastal North Carolina was conducted by North Carolina State University, East Carolina University, and the University of North Carolina at Chapel Hill (1979). The major findings of this study were:
1) The discharge of secondary effluent through an ocean outfall should not adversely affect the receiving water or ocean fishery resources although some build up of effluent constituents may occur in bottom sediments in the immediate vicinity of the diffuser;
2) Such discharge should have no effect on recreational swimming in the ocean;
3) Areas now closed to shellfishing in the estuaries because of wastewater discharges from septic tanks and treatment plants could be reopened as a result of diversion of effluents to the ocean; and
4) "Centralized sewer systems will increase land values, allow reduced lot size and stimulate growth."
While the last conclusion certainly accords with conventional wisdom and experience, a sewerage system need not stimulate growth. As the above report itself points out". . . existing regulations relating to erosion control and coastal development, as well as local zoning ordinances can be applied to control these undesirable effects."
Studies for ocean outfalls in North Carolina have heretofor been based upon a minimum of secondary treatment prior to discharge, in accordance with the requirement of the Federal Water Pollution Control Act Amendments of 1972, PL 92-500. In this study, the possibility of using primary treatment is not excluded for several reasons:
1) Many ocean outfalls using only primary treatment are operating successfully.
2) The principal purpose of secondary treatment is to reduce biochemical oxygen demand so as to exact lesser demand on oxygen resources in the receiving waters. Dissolved oxygen is seldom limited in the ocean. Ocean discharges through well-designed diffusers should achieve 100:l dilution and effect little change in DO levels in the ocean, even in the vicinity of the outfall.
3) Secondary treatment is far more costly in both money and energy than primary treatment, and with both of these resources in increasingly limited supply, the arbitrary provision of secondary treatment is inappropriate.
4) Relaxation of requirements for secondary treatment prior to ocean discharge is already becoming well established. The Clean Water Act of 1977, PL 95--217, authorized waivers for secondary treatment, based primarily on pressures from West Coast communities. More significant for North Carolina are the new regulations adopted by EPA on June 8, 1979 which allow primary treatment prior to ocean discharge so long as certain conditions are met; such as a requirement to meet established water quality standards, the provision of adequate pretreatment and the establishment and execution of a proper monitoring program. However uncertainties with regard to the acceptability of primary treatment still exist as elaborated upon in Chapter V.
The studies made herein do not accept that secondary treatment is a mandatory requirement, and both primary and secondary treatment with and without chlorination are evaluated.
Land Application. Application of wastewater to land as a treatment method is not new. Edinburgh, Scotland began using land application in the 1600's. The practice continues. Many cities in 13;rope and-England initiated land application systems in the 19 century: Paris 1869, Berlin 1874, Braunschweig 1896, Moscow 1900. Berlin and Braunschweig are still operating today as is the 96-mgd facility which began operation in Melbourne, Australia in 1898 (Hartman, 1975). Land application was also adopted in the United States in the late 18001s, particularly in the arid areas of the west.
As wastewater treatment technology developed, many municipalities abandoned land application in favor of treatment plants. In the last two decades, a concern for higher water quality in streams has again stimulated interest in land application, generally with pre-treatment. A continuing concern with land application is the impact on groundwaters particularly where these are a source of water supply.
Systems. Land application systems are generally grouped into three categories:
(a) Infiltration--percolation The objective of this system is to maximize water filtration and recharge to the ground water. Very permeable soils receive large applications of wastewater (10 to 500 ft/year). BOD and suspended solids are reduced and there is some nutrient removal by soil and crops. Precise management is required to induce nitrogen reduction by nitrification and subsequent denitrification. Overland flow With this method wastewater is allowed to flow through vegetation (usually grass) on the surface of a slowly permeable soil. Application rates range from 5 to 25 ft/year. The BOD and suspended solids are removed and nitrogen removal is high due to denitrification. Phosphorus removal is low because there is little contact between the wastewater and the soil.
Irrigation Wastewater is applied to permeable soils through spray, furrow or flood irrigation. Application rates vary from 1 to 10 ft/year. BOD and suspended solids are almost completely removed, phosphorus is removed by reacting with the soil and by crop uptake. Nitrogen is removed mainly through crop uptake and to a lesser extent by deintrification. This is the system proposed for use in the coastal areas of North Carolina.
Pretreatment. Treatment of wastewater prior to land application is necessary to (a) prevent nuisance odors, (b) prevent clogging of the irrigation system (c) reduce pathogen levels and (d) reduce the level of a particular constituent to reduce the amount of land required. From the standpoint of the soil being able to function continuously as a treatment medium, primary treatment of domestic wastewaters is usually sufficient (Jones and Lee, 1977, Palazzo, 1976).
Application Sites. There has been considerable interest in applying wastewaters to forest lands. Forested areas are usually on less productive soils and land costs are generally lower than on cleared sites. Forest soils have high infiltration rates and consequently there is virtually no runoff hazard. Land clearing, crop establishent and crop production are not required so capital and operating costs are lower than for agricultureal sites. Above ground irrigation systems are generally used and thus installation costs are low.
The disadvantages of forested sites include low revenue production compared to agricultural sites and high maintenance cost for above ground systems especially during freezing weather. However, the biggest disadvantage is the low nutrient removal in forested sites because there is no crop harvest. For the first few years the increase in forest biomass and soil organic matter provides a sink for the applied nutrients. However, when a new equilibrium is reached nutrients begin to move out of the root zone. Although phosphorus may be retained in the soil through reactions with the soil, nitrogen will move as nitrate to the ground water. In studies of application of secondary effluent to a hardwood forest in Pennsylvania it was found that in the last seven years of the nine-year study the amount of N leached below the root zone was equal to the amount of N applied (Hook and Kardos, 1978).
Applying wastewater to agronomic crops has the advantage of greater nutrient removal via crop harvest and greater revenue from the sale of the crop. Perennial grass crops are well suited to land application sites because they have high N uptake rate, provide continuous ground cover, and require no annual tillage operations. Coastal bermudagrass overseeded with rye in the winter is an example of a cropping system suited to land application sites in the coastal areas of North Carolina. In contrast to forested sites, agronomic sites require a higher degree of management to coordinate wastewater applications and crop production.
In areas of the west where water is scarce, golf courses, airports and parks are often irrigated with treated wastewater. Examples are San Francisco, Colorado Springs, Las Vegas, and La Mesa, Texas (Sullivan, Cohn and Baxter, 1973). By this use a municipality can reduce land costs for wastewater treatment while conserving its water supply.
Application Rates. Several factors must be considered in determining the rate at which wastewater may be applied to land. These factors include the allowable loading rates for:
water (hydraulic loading rate) nutrients organics salts heavy metals
The size of the land application site will be dictated by the loading rate that requires the largest amount of land. With municipal wastewater from domestic sources, the land area is usually dictated by hydraulic or nutrient loading rates.
Hydraulic Loading Rate. The allowable hydraulic loading rate is a function of climate and soil properties. It can be estimated by developing a water budget:
Precipitation + Irrigation = Drainage + Evapotranspiration + Runoff Although runoff from a land application site is undesirable, it may occur during heavy rainstorms. However, to be conservative in determining the allowable irrigation rate, it is assumed that runoff is zero, i.e., by eliminating runoff from the right side of the equation the controllable input of the left side (irrigation) must be reduced.
Precipitation and evapotranspiration can be obtained from weather records but drainage must be estimated. In estimating drainage it is assumed that wastewater (and/or rainfall) is applied in sufficient quantity to saturate the permeable surface horizons. The soil then drains until drainage becomes very slow (field capacity). Drainage from saturation to field capacity takes from 112 day for very sandy soils to 5 days for silt loams. After field capacity is reached, it is generally recommended that at least three days be allowed for the soil to reaerate. Thus the total cycle consists of: Irrigation time + Drainage Time + Reaeration Time The monthly drainage rate can then be determined:
30 da~s/month X water applied/cycle = water drainedlmonth days/cycle
For a Lynchburg soil (Morehead City area) the water budget would be developed as follows:
1) Surface layer, 0 - 12, in. depth 2) Moisture held between saturation and field capacity, 25% by volume (Lutz, 1970) 3) Cycle a) Irrigation time, 1 day b) Drainage to field capacity, 3 days (Lutz, 1970) c) Reaeration, 3 days d) Total cycle, 7 days 4) Drainage/cycle, 12 in. x 0.25 = 3 idweek 5) Monthly drainage 13 inlmo
The water budget for 1953 (wettest year between 1951 and 1960) is shown in Table 1-5. The average allowable irrigation rate for this year is 10.44 in/mo or 2.4 in/wk. Maximum storage required is 10.44 in., i.e., 10.44 acre-in. of storage for each acre irrigated. In this case sufficient storage would be required to hold one month of wastewater flow.
Nutrient Loading Rate. Nitrogen and phosphorus are the two nutrients of concern in land application systems because of their effect on eutrophication and because of the nitrate hazard in drinking water.
Nitrogen applied to irrigation sites can follow several pathways. During irrigation and subsequent drying of wastewater on soil and plant surfaces, some ammonia nitrogen will be lost as ammonia gas. As soils on the site contain more moisture than unirrigated sofls, there is a higher rate of denitrification with subsequent gaseous loss of N. Crop uptake accounts for a large fraction of the applied N. Immobilization of N by microbes provides a temporary sink but under steady state conditions there will be no net effect on the N budget. Finally, nitrate nitrogen moving below the root zone will ultimately reach the groundwater.
Because of the gaseous losses of N from land application sites, it is possible to apply wastewater at a rate to supply 1.5 times the fertilizer N rate normally recommended for specific crops without causing groundwater nitrate hazards. The cropping system suggested for land application sites in this study is hybrid bermudagrass (Coastal or Tifton 44) overseeded in the fall with rye. The recommended fertilizer N rate for this cropping sequence is 500 lb N/acre/yr. Rather than use the 1.5 factor, a more conservative N rate of 600 lb N/acre/yr is used as an upper limit in this study. Table 1-5. Water budget for Lynchburg sandy loam (fine-loamy siliceous, thermic, Aerimic Paleaquults) in Morehead City area, 1953.
Allowable Cumulative Month ~va~otrans~irationl/- Drainage precipitation2/- Irrigation storage3/- storage4/-
TOTAL 66.89 MEAN 10.44
-1/ from (Carney, Hardy and Van Bavel, 1977) -21 from (Climatic Summary Supplement, 1960) -31 Storage = mean irrigation - allowable irrigation -41 Begin cumulative storage with an empty basin, e.g., July-August Phosphorus applied to soil follows fewer pathways than does N. Crop uptake will remove significant P from the site. Reactions between P and aluminum, iron and calcium in the soil remove P from the soil solution and prevent it from leaching into the groundwater. The P/N ratio in wastewater water is much higher than the P/N ratio required for adequate crop nutrition. Thus if wastewater application rate is based on N loading rate, P will be applied in excess of crop needs. It is quite important that this excess P react with Al, Fe or Ca to prevent its movement into the groundwater and subsequently to surface water.
The P fixing capacity of sandy coastal soils has not been researched extensively because their capacity is generally low. Since P fixation is a liability in crop production, most research has been conducted with clay soils where P fixation is high. Preliminary laboratory studies suggest that the soils on Roanoke Island and on the mainland in Carteret County have adequate P fixing capacity to handle P loading rates in excess of crop uptake rates (L. D. King, 1978). However, pretreatment of wastewater for P removal may be necessary on the Outer Banks,
Organic loading rate, Permissible organic loading rates vary with soil texture and soil drainage and range from 1000 to 4000 lb Total Oxygen Demand (TOD)/acre/week (Carlile and Phillips, 1976). As municipal wastewater contains only about 200 mg/l of TOD (45 lb TOD/acre-in) the organic loading rate will not be a significant factor in setting the irrigation rate.
Salt Loading Rate. The two main concerns with wastewater salt content are the effect of the total dissolved salts on crop growth and the effect of sodium on soil permeability. If the total dissolved salt content (or electrical conductivity) is high then crops can be damaged by direct salt injury, i.e., an osmotic effect that reduces intake of water by the roots. Conductivities of wastewater effluent from the western areas of the U. S. may range from 1 to 2 mmhos/cm (Pound and Crites, 1973). Conductivities of effluents from humid areas such as North Carolina should be less because of the lower dissolved salt levels in the drinking water supply. A possible exception would be in areas where brackish water may infiltrate the sewer system.
Coastal bermuda grass will suffer no yield reduction from irrigation with water having a conductivity up to 5.8 mmhos/cm (Carlile and Phillips, 1976). Consequently salt content of the wastewater will not be a significant factor in setting the irrigation rate.
If the sodium absorption ration (SAR)" of wastewater is greater than 5, Na will accumulate on the cation exchange sites in the soil to a level that will cause deflocculation of the clay. This deflocculation will cause a reduction in soil permeability. The SAR of effluents from humid areas are
"SAR = Na where concentrations of the elements are expressed in J1/2 (Ca + ~g) milliequilavents/l. generally below 5 (Kardos, 1973) so no deflocculation problems should result from application of effluent to land.
Heavy Metal Loading Rate. Current EPA heavy metal regulations base allowable loading rates on soil cation exchange capacity (CEC). Data in Table 1-6 show the heavy metal concentrations in domestic sewage effluent and the allowable loading limit for soils with CEC values between 0 and 5 meg/100 g. Cadmium is the limiting element but at an assumed 2-inch application rate the life of the site is still much greater than the 20-year design period used in this study.
Heavy metals limits shown in Table 1-6 are for privately owned land. For publicly owned land where the metal content of the crops are monitored, higher application rates of metals are allowed. Consequently heavy metals are not significant in determining the irrigation rate.
Pathogens. In comparing land application of wastewater with conventional disposal it is necessary to evaluate the relative health risks of the two systems. Unfortunately, insufficient data are available. Perhaps the best measure of health risk associated with land application is the long history of this practice and the lack of any documented evidence of disease outbreaks from properly operated land application system (USEPA, U. S. Army Corps of Engineers and U. S. Dept. of Agriculture, 1977).
Table 1-6. Heavy Metal Loading Rates
Concent rat ion Allowable limit Design life at Metal in effluent 11 over life of site 2/ 2 in. effluentlwk
Ppb lb/A years
-1/ (Jones and Lee, 1977) -2/ Based on soil CEC of 0-5 meg/100 g (1) (Carlile and Phillips, 1976) Pathogens in wastewater include bacteria, viruses, protozoa and parasitic worms. With the exception of viruses, treatment is effective in reducing the population of most of the pathogens. Table 1-7 shows the effect of secondary treatment plus chlorination on pathogen survival. It is evident that virus will be of greatest concern as they are least effectively removed by treatment. A higher degree of treatment is effective in removing viruses. For example at St. Petersburg, Florida, influent samples averaged 71 plaque forming units (~F~)/liter. After receiving activated sludge secondary treatment, alum addition, filtration and chlorination the virus count ranged from 0 to 0.003 ~FU/liter(Wellings, Lewis and Mountain, 1977).
Selecting sites and designing land application systems is somewhat like designing an ocean outfall. An ocean outfall extends far enough from land that by the time any wastewater is carried back to the beach, bacterial concentrations will be at an acceptable level as a result of dilution and dieoff. Land~applicationsites and loading rates must be selected such that by the time wastewater reaches the groundwater, pathogen concentrations will be at an acceptable level due mainly to dieoff.
Survival of bacteria and viruses is affected by various soil conditions. Survival is greater in moist soils and at low soil temperature. Bacterial survival also is enhanced by a neutral pH, high organic matter and lack of microbial competition. Once bacteria and viruses reach the groundwater their survival is greater than in the soil because of the lower temperature and the absence of sunlight and antagonistic microorganisms.
Table 1-7. Effect of Pretreatment on Pathogen Survival and the Infective Dosage of Pathogens
Wastewater Number required Secondary Treatment to cause Organism Untreated plus chlorination infection
Salmonella 530 0.01 lo4-109
Entamoeba 0.4 histolytica
Melminth ova 7 1 X 10-4 --- Human enterovirus
(USEPA, et al., 1977) Survival on crops is a function of the microenvironment. On the lower portions of plants where conditions are moist and dark, bacteria may survive for 30 to 40 days. However, on the upper portions of plants, survival is limited because of desiccation and sunlight.
Land application systems should retain pathogens in the soil for a sufficient period to allow dieoff to occur. Most bacteria are retained in the upper layers of the soil by a combination of sedimentation, straining, and adsorption. Here survival is limited because of sunlight, oxidation, desiccation and antagonism. Soils with subsurface fissures should be avoided because of the possibility of short circuiting of wastewater directly to the groundwater.
Viruses are retained in soil by adsorption. Viruses may be positively or negatively charged depending on pH. Above pH 5, most viruses are negatively charged. Thus within pH ranges generally found in topsoil, viruses are negatively charged. As soil clays are negatively charged, viruses are thought to be adsorbed through a cation bridge. Studies have shown that adsorption is enhanced by increased concentrations of divalent cations in solution. Viruses tend to be eluted after heavy rains, probably a result of dilution of the divalent cation concentration. Recent studies have shown that 6-in. deep columns of Newhan sand (common on the Outer Banks) were very effective in adsorbing viruses seeded into primary effluent. However, additions of distilled water (to simulate rainfall) resulted in elution of many of the absorbed viruses (Sobsey, 1978). Management techniques which might be used to reduce elution after rainfall include wastewater irrigation during or after rainfall or periodic applications of CaS04 to maintain a high Ca concentration in the soil solution.
Inland soils are more effective in absorbing viruses than soils on the Outer Banks because of higher clay contents and lower pH values in the subsoil.
Another health risk in land application is the spread of pathogens through aerosols. This risk is also associated with conventional treatment facilities (Leffel, 1976). Pathogens encapsulated in small droplets of water may be carried a considerable distance by the wind. Aerosol spread can be reduced by use of low pressure irrigation nozzles, planting trees in buffer zones around the application sites to reduce wind velocity and to trap aerosols on the foliage, and irrigating during the day to speed up the drying of the aerosols and to expose the pathogens to ultraviolet radiation in sunlight. On the other hand, to avoid direct human contact with sprays and aerosols, spraying is often restricted to night hours. (Okun, 1979).
While there are insufficient date available at present to predict a specific pathogen risk from aerosols, it can be concluded that sites located on the Outer Banks pose a greater hazard because of the very sandy nature of the soil and the strong winds from the sea than sites on Roanoke Island and the mainland in Carteret County, which posed less hazard because of more finely textured soils, lower soil pH and lower wind velocities. Nitrate in Groundwater. Another health aspect of land disposal is movement of nitrate into groundwater. A rough estimate of this can be developed from N loading rate, climatic data, crop uptake and estimated gaseous losses of N. Below is an estimate for the Roanoke Island land application site. This estimate should be fairly typical of all sites in the study areas.
The annual nitrate input to the groundwater isdestimated as shown in Table 1-8. In 2025, 54 lbs/acre/yr of nitrate nitrogen would move below the root zone and into the groundwater. This nitrate would be in the 56 in. of drainage water moving through the soil. Therefore, the average annual nitrate-nitrogen concentration would be 4.2 g/l, many orders of magnitude less than standards for drinking water.
Wetland Application. It has been known for some time that wetlands act as natural filters. Several research and pilot scale projects have been developed to determine the effectiveness of wetlands for wastewater treatment (USEPA, et.al., 1977). To date there are no installations incorporating wetland treatment into a large-scale treatment system.
Wetland treatment is somewhat analogous to the overland flow system, i.e., wastewater is treated as it moves over the surface of the soil. Consequently, most of the treatment is effected by plants and microorganisms rather than by soil chemical processes.
Nitrogen removal is by plant uptake and denitrification. Wetlands have been shown to effect high rates of denitrification (USEPA, et.al., 1977). This results from the double layer present in wetlands:
1) A surface layer of water remains aerobic and here organic nitrogen and ammonia are converted to nitrate;
2) The nitrate diffuses into a substance layer of water (or into the soil water) where anaerobic conditions exist and available carbon from organic matter is plentiful. In this layer nitrate is denitrified.
Phosphorus removal is mainly by crop uptake as wastewater contact with soil is minimal. Unless plants are harvested it appears that the steady state P retention capacity of wetlands would be limited.
Pathogen removal in closed wetlands would be high as effluent would have to seep through slowly permeable soils. In open wetlands, where wastewaters would flow overland, pathogen removal may be limited.
Attempts have been made to place a monetary value of wetlands as tertiary treatment sytems (Gosselink, Odum and Pope, 1974). It is here considered that wastewater be given conventional secondary treatment to prevent overloading the wetlands with BOD and that wetlands substitute for conventional tertiary treatment systems. Table 1-8. Estimated Quantity of Nitrate-Nitrogen Which Would Enter the Groundwater Below the Roanoke Island Sites.
Design Year
Water input precipitation1/- Irrigation Total
Evapotranspiration (ET) 2/ 36 36 36
Drainage (water input - ET)
Nitrogen input
Denitrification loss (assumed to be 15% of input)
Coastal bermudagrass Rye Nitrogen lost in drainage (input - denitrification - uptake
Average nitrate-nitrogen concentration of drainage water 0 1.8 4.2
-- -- -11 (Climatic Summary Supplement, 1960) -2/ (Carney, Hardy and Van Bavel, 1971) The EPA has issued a policy statement relative to the protection of the I nation's wetlands which is applicable to consideration of wetlands as a means I for treatment and disposal. It is the policy of the EPA "not to grant Federal funds for the construction of municipal wastewater treatment facilities or other waste treatment associated appurtenances which may interfere with
I existing wetland ecosystem except where no other alternative of lesser I environmental damage is found to be feasible". Nevertheless, wetlands may be entirely appropriate for receiving compatible wastewaters.
I Because available wetlands in the study areas are a considerable distance from the populated areas to be served, preliminary studies indicated that even if this were a proven and entirely feasible method of disposal, the costs would be substantially greater than the other options available. Consequently little further attention is given to wetland disposal in this report.
Water Reuse. Wastewater reclamation, through treatment and reuse for nonpotable purposes, which is beginning to be an important option in wastewater management, requires the use of dual water supply systems, one for potable purposes and the other for nonpotable purposes. Such systems are beginning to be widely introduced (Envirnomental Protection Agency, 1980). Their advantages are:
1. Where water supplies of high quality are limited, water reuse for nonpotable purposes can replace waters of potable quality, thereby permitting the high quality sources to serve a larger population.
2. Where wastewater disposal restrictions are severe and a high degree of treatment beyond secondary treatment is required, the high-quality effluent constitutes a resource and water reuse becomes a viable option. Inasmuch as most nonpotable reuse is for irrigation, reuse obviates the need for nitrogen and/or phosphorus removal, as these are valuable constituents in a water to be used for irrigation,
3, Water reuse may be more economical than developing new potable water resources. While reuse has been practiced extensively in the arid western regions of the U. S., reuse is beginning to be attractive even in the humid east. For example, St. Petersburg, Florida, faced with tight restrictions on wastewaters to be discharged to Tampa Bay, found that water reuse through a dual system is more economical, more conserving of limited water resources, and more protective of the environment than treatment of the wastewaters for disposal to sea.
Reuse would appear to be an option for consideration in coastal North Carolina. Accordingly, water resources in the two study areas were examined. In the southern area, the availability of ample water supplies from the Castle Hayne aquifer virtually eliminates any need for water reuse, at least so far as water supply is concerned. In the northern area, however, water resources are not clearly so plentiful and a study of resources in this area was undertaken (Appendix). Ample water resources are available in the Dare County area for the present and until the year 2020, so that here too the potential for water reuse is extremely limited. Furthermore, low densities of population in the coastal areas of North Carolina severely limit urban nonpotable reuse possibilities. With agricultural utilization on the coast also limited, the potential for nonpotable reuse is not now believed to be worthy of detailed study. For reuse to be economical, there must be several larger users, or clusters of users, that can be served with water of nonpotable quality. Otherwise, a second distribution system for nonpotable water would be exceedingly costly.
This is not to conclude that in other areas of coastal North Carolina, such as Wilimington, or in the future, reuse might not be a feasible and economical option. Certainly it should be added to the options available to communities as they consider their water requirements in the long term.
Costs
Capital cost and the present value of operation and maintenance (0 + M) costs are obtained for the treatment and disposal plans by use of cost functions. These costs functions are obtained from two main sources: Camp, Dresser and McKee, Inc. and the Environmental Protection Agency, and are adjusted by the Engineering News-Record construction cost index.
A design life of 20 years and a discount rate of 6 percent are used to obtain present value for 0 + M costs. Due to the great fluctuations in flows on a seasonal basis, 0 + M costs are calculated separately for the summer and winter months. In the cost functions dealing with the treatment facilities, the 1990 summer and winter flows are used to represent an average annual 0 + M cost over the 20-year period.
Interceptor Sewer System--Gravity Sewers. The capital costs for gravity sewers are obtained from Camp, Dresser and McKee (1972). These costs include engineering and contingencies, excavation, backfill, dewatering, laying pipe and paving replacement.
In the computer program where these costs are utilized, the cost input to the program is that of a pipeline with its invert at a depth of 8 feet. This is the average of the required invert depth of 4 to 12 feet. These costs are shown on Table 1-9. An 0 + M cost of 0.6 percent of the capital cost is used (CDM, 1972).
If the program ends with a section of pipe less than 1,000 ft., the preceding pump station is ignored and the extra length is added to the preceding pipe section as an additional lift station is not warranted. Between two tee manholes, a large diameter pipe may be needed for only a short length. This does not allow the pipe to drop the full 8 ft. because the program gives a single cost for a certain diameter pipe based on an average invert depth of 8 ft for the run. These errors are small and tend to cancel each other. Pump Stations. The cost functions for pump stations are obtained from CDM (1972). These costs represent installation and upkeep of an entire pumping station and provide a peaking factor of four-thirds of the design flow. (See Table 1-9.) When the cost function is used to determine the operation and maintenance cost of a pump in the interceptor sewer system, the flow used in the function is the summer and winter flow for the year 2000. However, when the same function is used to determine the cost of an effluent pump station, the flow used in the function is the summer and winter flow for the year 1990. The resultant higher cost of the interceptor pumping stations is justified as the low winter flows may require adjustment of the float levels, flushing of some wet wells and possible chlorination to prevent septic conditions in the wet wells. The effluent pump stations would pump treated water and would not have these problems.
Force Mains. Force main capital costs are obtained from Camp, Dresser, McKee (1972). This cost includes installation of the force main with the invert depth at about 4 feet, and providing at least 2 feet of cover at all times. (See Table 1-9.)
Force mains are used in this report as transmission mains to cross the sounds, and as subaqueous effluent outfalls into the sounds. In each of these applications, the cost is adjusted to account for uncertainties. When crossing a sound via a continuous bridge, the force main may be hung from the bridge. As the pipe is exposed, a change in materials is required and a factor of 150 percent is used to represent this. When crossing a sound via a swing bridge, the force main must be subaqueous to a depth great enough to avoid any dredging equipment that may be used to keep the channel open. The length of the subaqueous section must span the length of the swing section. The cost of this section may be as high as ten times that of a normal pipe section. To reflect this, the force main cost is doubled over the entire length of the bridge.
When a force main is used as an effluent pipeline, the section that is subaqueous must be of a material that will withstand corrosion. It must also be anchored to the bottom or buried. The cost of subaqueous mains used as effluent pipelines are multiplied by a factor of two. A factor of 0.6 percent is applied to all capital force main costs to obtain 0 + M costs. Treatment Costs. Cost functions for a majority of the treatment processes are obtained from "A Guide to the Selection of Cost Effective Wastewater Treatment Systems" by the Environmental Protection Agency (July, 1975). These processes are: preliminary treatment, primary treatment, chlorination, activated sludge, anaerobic digestion (secondary), drying beds (secondary), filtration, nitrification, trickling filter and in-plant pumping. Table 1-9. Gravity Sewers, Force Mains and Pump Stations
Gravity Sewers
Diameter cost ($/ft. ) Cost ($/ft) (inches) 8 ft. invert 4 ft. invert
8 39 12 4 2 15 48 18 56 2 1 6 1 24 70 30 87 36 109 4 2 133
Force Mains
Diameter cost ($/f t) (inches 4 ft. invert
Pump Stations
K = 242,447 20-5 = Capital cost in dollars as of July 1, 1977
Z = Design flow (MGD) in Summer, 2000
C = (9.1 + 0.03 H) 40.59 = 0 + M cost in $/year in July 1, 1977 dollars
H = Total head in feet
Q = Design flow (MGD) (Summer and winter - 1990 or 2000) These cost functions include land costs for the various treatment processes. (See Table 1-10). "Dual Chlorination" is required when discharging effluent to "SB" waters. The cost of this is obtained by doubling the conventional chlorination costs. A different sludge volume is generated by each of the treatment processes included here, and thus a different function is necessary for each process. The conventional activated sludge trickling filter and primary treatment processor generate 2340, 1720 and 1250 pounds per day of dry sludge per million gallons of influent respectively. (Metcalf and Eddy, 1972). Nitrification generates an additional 36 pounds per day of sludge per million gallons of influent. To obtain capital and present value O+M costs for primary treatment, anaerobic digestors, drying beds and hauling sludge to a landfill, it is necessary to multiply the cost function by a ratio of the volume of sludge expected, divided by the volume of sludge obtained in a conventional activated sludge process.
The O+M costs are obtained for summer and winter using 1990 flows. These flows are used to obtain an average annual O+M figure over the 20-year period.
Phosphorus removal costs are based on a chemical precipitation process [Camp, Dresser, McKee, (Inc.)].
Costs for a modular activated sludge facility are obtained from Camp, Dresser, McKee (1975). This package plant cost is used to enlarge facilities that are presently using such units. (See Table 1-11).
After the sludge is dried in the drying beds, it must be disposed of in a sanitary landfill or to other land. The cost to transport this sludge is 25 dollars per ton, as obtained from the Dare County Complex 201 Facilities Plan. (Von Oesen, 1976).
Ocean Discharge. The cost of an effluent pump station is estimated from the following cost function (CDM, 1975).
Capital cost C = 322000~~~~~ Annual 0 + M cost C = (8.20 + 0.03H) (1000)~0*59 where C = dollars H = head feet Q = average daily flow in MGD This cost function yields higher costs than that used previously for pumping in the interceptor sewer system. This higher cost is used to represent a greater complexity of design of this pump station, such as the ability to withstand salt water corrosion, and the ability to achieve an optimal hydraulic performance of the outfall.
The capital cost of the ocean outfall is obtained from the following cost function developed elsewhere in this report,
c = 157 eOe022D where C = costllinear foot D = diameter in inches Table 1-10. Cost Functions for Treatment from EPA (1975) (Adjusted to July 1977)
1) Preliminary Treatment
100 M = (1413 + 146 Q) MHR + (1434 + 410 Q) Primary Treatment - conventional K = 1194,625 + 24,584 Z + (0.32 + 0.12 Z) ULC] (loo + SIF) 1 nn I uu M = 1898 40.42 MHR + 1844 Q0-62 Chlorination K = [87,069 + 7170 Z + (0.29 + 0.025 Z ULC] (100 + SIF) 100 M = 474 ~0.6~MHR + (-2868 + 4507 Q) Activated Sludge K = [500,900 + 117,800 Z + 1.05 ~0.8ULC] (100 + SIF) 100 M = 4686 Q0e45 MHR + 17,414 ~0.~3 Anaerobic Digester - secondary K = (154, 675 + 32,779 Z + [0.55 + 0.12 Z] ULC) (100 + SIF) 100 M = (945 + 111 Q) MHR + 2254 + 205 Q Drying Beds K = (20,487 + 80.923 Z + 12.05 + 2.66 Z1 ULC) (loo + SIF)
M = Q MHR + 9.2 + 1332 Q (O.OOOS31 + 0.00001189 Q) Filtration K = (322,666 ~0.6~+ [0.034 + 0.039 Z] ULC) (100 + SIF) 100
Nitrification K = (292,960 + 82, 459 Z + (0.70 20-84 ULC)) (100 -I- SIF) 100 M = (3589 + 197 Q) MHR + 14341 q0o75 Trickling Filter K = (324, 715 + 117,799 Z + 1.67 ~0*81ULC) (100 + SIF) 100 M = 2620 Qoo51MHR + 6658 + 1434 Q 0 + M = operation and maintenance cost (July 1, 1977 $/yr) K = capital cost (July 1, 1977 dollars) Z (for capital costs) = design flow (summer) 2000 Q (for 0 + M costs) = design flow (summer + winter) 1990 SIF = service and interest factor = 27 ULC = land cost = $6000/acre Outer Banks $5000/acre Roanoke Island $3000/acre Bogue Banks $2500/acre Main land MHR = labor rate = $5/hour
Table 1-11. Package Plant Cost Function (Modular Activated Sludge Plant)
0 + M = 0.117 x 106 40.7
K = Capital costs (July 1, 1977 dollars)
0 + M = Operation and maintenance costs (July 1, 1977 dollars)
Z = Design flow Summer 2000
Q = Design flow 1990 summer and winter
Land Application
The base for costs estimated for land application systems are shown below:
Aerated lagoons capital costs are taken from Dames and Moore (1978). The "warm climate" curve was extrapolated linearly for flows greater than 0.5 mgd. The cost curve includes preliminary treatment, aerated lagoon, chlorination, pumping facilities, lining and laboratory and maintenance facilities. 0 & M costs were taken from Pound, Crites and Griffes (1975). Chlorination and chlorination 0 & M costs were taken from USEPA Office of Water Program Operations (1975). Storage and pumping costs were taken from Pound et al., (1975). Force Main costs are the same as those used for Interceptor system. Land costs: (a) Dare County - 20-20 Realty, Manteo, N.C. Outer Banks Realty, Manteo, N.C. (b) Beaufort - Blankley Realty, Beaufort, N.C. (c) Morehead City/Newport - Balco Land and Timber Co., Morehead City, N.C. (d) Cape Carteret - Carteret Properties, Cape Carteret, N.C. Land Preparation costs were taken from Pound et al., (1975) except that land clearing with trees cut at ground level and stumps not removed were estimated at $600/acre from current cost of land clearing in the coastal area (Carlile, 1978) and smoothing of dunes to permit center pivot irrigation and hay harvesting at $750/acre (Outer Banks Contractors 1978). Crop production costs for establishment and production for Coastal bermudagrass was taken from Dames and Moore (1978). Fertilizer cost ($84.85/acre/yr) was deducted from production cost as the effluent would supply adequate nutrients in most cases. The lower application rates used on the Dare Beach area will not supply sufficient nutrients during the early years of the design period. Consequently, production costs for these sites were increased by $14/acre/yr to cover the cost of supplementary nitrogen fertilizer to be used in the early years. There are no cost data on rye overseeded in bermuda grass so the cost was estimated by adding the cost of rye seed to half the cost of bermudagrass production. As the winter application rate on the Dare Beach sites is low, rye yields will be lower and thus it is assumed that production cost equals revenue . Irrigation systems costs were determined from Pound et al. (1975) except that center pivot systems were estimated as Capital cost ($/acre) = 832 - 2.94 x acres from Sneed (1979) and fence at $2.60/ft (Security Pence Co., Raleigh, N.C.) 0 & M cost--Figure 41 (Pound, et al., 1975).
No salvage value is applied to the land costs. Although some of the lands utilized for land application are multiple purpose lands that would not have to be purchased, a majority of the land would have to be purchased. This land can be resold after it's value as a land application site is exhausted. However, due to the lack of suitable sites in the study areas, it is assumed that these sites will continue to be used as land application sites after the twenty-year planning period. Thus, no salvage value will be realized at the end of the planning period. Chapter 11
WASTEWATER MANAGEMENT IN THE NORTHERN (DARE COUNTY) COASTAL AREA
The Dare County area is heavily dependent on its ocean and coastal waters for tourism and on the latter for shellfish production. The water-bearing strata beneath the islands are interconnected. The unconfined acquifer is the means of recharge for Freshwater Pond, the water source for Nags Head and Kill Devil Hills. This acquifer is subject to contamination by septic tank effluents, This contamination could spread to the confined acquifer, the 'principal acquifer'. Contamination of the acquifers may, and in many instances has, lead to contamination of neighboring areas into which these acquifers drain. Proper treatment and disposal of the wastewaters of the Dare County area is important to maintaining the integrity of the area.
Area Description
The Dare County study area is located in the tidewater section of the northeastern North Carolina entirely within Dare County, bordering the Atlantic Ocean. (See Map 1-1.) The area comprises the barrier beach island, extending from Oregon Inlet on the south to the Currituck County line on the north, and Roanoke Island, which lies between the barrier beach island and the mainland to the west. It includes the incorporated communities of Nags Head and Kill Devil Hills and the unincorporated communities of Kitty Hawk, Southern Shores, Duck and Whalebone Junction on the barrier island. Manteo and the unincorporated community of Wanchese are both on Roanoke Island.
The land areas are generally low lying with elevations averaging from just above sea level in the marsh lands to about 10 feet above mean sea level. The exceptions are the dune areas on the Dare Beaches which range in height between 15 and 20 feet, with unique dune formations some 150 feet in elevation. The Outer Banks are about 4 miles across at the widest point and narrow to less than 0.25 miles in the portion north of Duck. Roanoke Island lies roughly parallel to and about 1.5 miles behind the barrier island and is approximately 11 miles long and between 1 and 2 miles wide. The island is surrounded by four sounds: to the north--Albemarle Sound; to the south-- Pamlico Sound; to the east--Roanoke Sound; and to the west--Croatan Sound.
Economy and Major Employment-Generating Activities
The economy of the Dare County area is based primarily on the tourist industry, During the peak summer season, retail trade employment accounts for about 40% of the total. Within this segment, eating and drinking establishments account for 21% of the peak employment on Dare Beaches. Employment by hotels, motels and other lodging places accounts for 26% of the total peak employment. Other major categories include entertainment and the recreation industry (8%) and the construction industry (7%). Fisheries, manufacturing and public administration collectively account for the remaining 8% of the total peak employment.
Tourist-related industries also dominate off-season employment. The services sector is the largest category with 32% of the total, followed by retail trade with 24%, construction with 16% and finance, insurance and real estate with 14%. The remaining 14% is made up of fisheries, manufacturing and public administration. In the manufacturing category, the two largest groups of workers are employed in preparing fresh seafood and in producing concrete for the construction industry.
The commercial fishing industry, although relatively mall in comparison to tourism, is important. There are two major docking faciltiies for commericial fishing vessels, Manteo (Shallowbag Bay) and Wanchese Harbor, both on Roanoke Island. Amajor port and fisheries processing facility for Wanchese Harbor is in the final stages of planning. This facility should serve to revitalize the fishing industry and provide a new opportunity for employment in the complex.
Land Use
On the barrier beaches, commercial land uses are dispersed throughout the area and are generally intermixed with other land uses. There are some concentrations of commercial establishments at Whalebone Junction and Nags Head; However a solid nucleus which could be classified as a business district does not exist. The majority of the commericial development in the Dare Beaches area is recreationally oriented. Restaurants, gift shops, entertainment facilities and gasoline service stations comprise over 60% of the total commercial development. The remaining 40% of the commercial land consists primarily of grocery stores, fishing piers with associated bait and tackle shops and commercial services such as realty offices, laundramats, barber shops, etc. The largest amount of developed land in the Dare Beaches area is occupied by motels, hotels, and other commercial-residential uses. With few exceptions, most of the land uses in this category are located between Route 158 bypass and the ocean beach extending from the Kitty Hawk area southward to the Whalebone Junction area of Nags Head.
Residential land uses are concentrated in the Duck area, at Southern Shores (Southern Shores Community), at Kitty Hawk Village, on Colington Island, in Kill Devil Hills, in Nags Head, west of Route 158 and in the southern area of Nags Head.
The majority of the public lands within the area (about 5000 acres) are held by the Federal Government (National Park Service). Most of this land is on the southern end of Bodie Island and in and around the Wright Brothers Memorial at Kill Devil Hills. The only public beaches are on the southern end of Bodie Island within the Cape Hatteras National Seashore. There are two golf courses in the area, Duck Woods at Southern Shores and Sea Scope. I Industrial land uses are negligible. The largest parcel of land use within this category is located in Nags Head and is used for the manufacture of concrete. A large portion of the beach area is categorized as conservation area. Commercial land use on Roanoke Island is centered mainly along US 64/264 in the form of scattered 'strip development'. Commercial development is centered in the town of Manteo. Limited commercial development is found in the Wanchese area in the southern portion of the island, but no concentrated nodes exist at present. Motels, hotels, and other commercial residential uses are not as extensive as on the barrier island. On Roanoke Island such usage , is scattered along US 64/264 and within the limits of the town of Manteo.
Public land uses are found mainly in the northern section of the island. The Manteo Airport occupies the largest tract of land, followed by the Fort Raleigh Historical Site. Industrial land use is confined to the dock areas in Manteo along Shallowbag Bay and at Wanchese Harbor, Finfish and shellfish processing is the chief industry. In contrast to the barrier island, Roanoke Island has some areas devoted to agricultural use. Small truck farms are located at Wanchese and one is located northeast of the town of Manteo. Some to 50% of the island consists of wetlands which are categorized as conservation areas.
Precipitation and Flood Control
The Dare County area enjoys a maritime climate with cooler summers and warmer winters than are to be found on the mainland. The mean annual rainfall at Bodie Island is 50.07 inches and at Manteo is 41.07 inches. The wettest months are July and August when there is a monthly average of nine days with thunderstorms. The mean annual temperature is 61.4OF. The earliest freeze in the fall is in December, and the latest freeze in February. Hurricanes are fairly frequent along the Outer Banks and occur mainly in August and September. Within the last 25 years, 18 have passed within 100 miles of Cape Hatteras, three of which are reported as having done "considerable" to "extensive" damage. The worst storm was the "Ash Wednesday storm" of March 7, 1962 which wreaked havoc in the Nags Head and Kitty Hawk areas, as well as opening a new inlet. Although some beach erosion and minor flooding occur regularly, major flooding occurs only when a storm of hurricane magnitude centers over the area. The fequency probability of these events is measured in terms of the 50 or 100-year frequency storms. According to the Corps of Engineers Report, Outer Banks Between Virginia ---State Line and Hatteras --Inlet, North Carolina --(1966), the 100-year flood levels are 8.8 feet above mean sea level for the Nags Head-Kitty Hawk area, and 8.1 feet above mean sea level for Roanoke Island. All mechanical equipment that might be damaged by flooding should be located above this predicted 100-year flood elevation.
Beach erosion, inlet migration, storm surge and breaking depth of waves are important in the design of sewerage systems in the area. Sewer lines and treatment facilities must be located away from those areas subject to erosion or inlet migration.
Beach and dune erosion is a natural occurrence, a part of the normal erosion/accretion process of migration of the barrier islands of the North Carolina coast. Studies utilizing aerial photographs have revealed that portions of the barrier island are eroding while other areas are experiencing a net gain in beach area (see figure 2-1). The beach strand south of Whalebone Junction has been subject to net erosion. The area with the highest rate of erosion is adjacent to Oregon Inlet, with an average loss of 7.7 feet per year. The beach strand north of Whalebone Junction to the Currituck County line has experienced a net accretion of the beach dunes. The recommended recession lines for treatment facilities and sewerage systems are shown on Table 2-1, No sewerage system appurtenances are planned to be within two miles of the center line of existing throat of Oregon inlet.
Water Supply in the Northern Area
The town of Nags Head and Kill Devil Hills and the population center on Colington Island currently derive their water supply from a surface fresh water lake called Freshwater Pond, located at Kill Devil Hills. This pond is approximately 35 acres in size and has a capacity of 90 million gallons. The waters of this pond are recharged by the unconfined aquifer. A number of shallow wells have been installed around the periphery of the lake to supplement the supply from the lake. This water is aerated and disinfected before being supplied to the towns. This system includes ground and elevated storage, The town of Manteo is supplied by a system of three deep wells which can provide 100,000 gallons/day.
These water supplies will be augmented during the summer peak season by the newly established deep well field on Roanoke Island. This well field is the first phase of the Dare Beaches Regional Water Supply Project. This project is a step toward regionalization of the water supply.
Water Resources in the Northern Area
The only reliable source of water supply in the region is groundwater. Three aquifers can serve as the potential sources for providing the water supply needs of the study area: (1) The water-table, or unconfined, aquifer; (2) the upper confined aquifer, and (3) the lower confined aquifer. The water-table acquifer has serious limitations in satisfying a large demand because of (1) the size of the fresh-water lens; (2) inadequate
transmissivity; (3) non-coincidence of periods sf greatest demand and periods of recharge; (4) proximity to the usually inundated areas; (5) probability of salt-water intrusion; and (6) possibility of contamination from septic tanks. The lower confined acquifer has a higher chloride content and is situated at a greater depth than the upper confined aquifer. The cost of developing a well system in this aquifer will be high. The upper confined aquifer, called the "principal aquifer," holds the greatest promise of furnishing a large supply of good-quality waters. The principal aquifer is nonhomogeneous and anisotropic. The transmissivity varies over a very wide range; from less than 1000 gpd per ft. at Kill Devil Hills to more than 60,000 gpd per ft. at the southern end of the Roanoke Island. The 1972 Report (Peek, Register and Nelson, 1972) identified three areas that were considered to be the most favorable for the development of groundwater supplies (Map 2-1): (1) southern Roanoke Island; (2) the mainland near Mann's Harbor; and (3) the Dare Beaches area from Kill Devil Hills to just south of Nags Head. Von Oesen Associates (Von Oesen, 1973) considered the southern half of the Roanoke Island as the most desirable and selected eight well sites for the first phase of the Dare County Regional Project. The system proposed by the consultants is now under construction. A study was undertaken in connection with this study to assess the adequacy of the principal aquifer to supply the peak summer demand for the year 2000 on a sustained basis without continually declining water levels. Details of the study are included in the Appendix. The water demand of the study area was estimated assuming an average daily per capita use of 100 gallons for the resident population and of 25 gallons for the day visitors. The projected water demand for the peak season for the year 2000 is 7.25 mgd. This level of demand will be attained only in the 90-day summer season. The projected non-peak season demand for the study area is only 1.2 mgd. The well system under construction was adopted as the starting basis. A digital computer model was developed and used to simulate the response of the aquifer to different pumping schemes. The aquifer was assumed to be confined and nonleaky. The model is capable of dealing with nonsteady flows in an elastic nonhomogeneous medium. The initial runs used transmissivity values given in the 1972 Report (Peek, et al., 1972). The drawdowns predicted by the model deviated significantly from the values obtained from the field pumping tests. Considerable effort had to be expended in collecting and analyzing additional information before a calibrated model could be developed. Most of the aquifer recharge is derived from the outcrop areas on the mainland. A weaker recharge area exists near the Manteo airport where the potentiometric levels are high. The aquifer was modeled with two recharge boundaries. The calibrated model was used to test if the principal aquifer can meet the peak season demand of 7.25 mgd in the year 2000 and not violate the objectives of efficient ground water management. Meeting the demand without causing an overdraft in the available supply means that ultimately a steady state with respect to the water levels must be reached. Moreover maximum drawdowns should be such that the pumping levels do not drop below the top of the confining aquifer thereby changing hydraulic response drastically. The investigation showed that the aquifer meet the demand of 7.25 mgd, a steady state is reached, and the drawdown constraints are not violated. However, this represents the full development of the aquifer as the steady state pumping levels drop to within a few feet of the top of the principal aquifer.
The off-peak season demand of 1.2 mgd in the year 2000 can be met by operating a fewer number of wells. The water levels in most of the area will recover substantially. The wells should be pumped in rotation. It is essential that every well be pumped periodically to maintain its hydraulic efficiency. The pumped wells should discharge close to their design capacity to maintain reasonable engineering efficiency.
The study indicated that the total present value of costs might have been reduced substantially if the construction of wells had been staged to correspond more closely to the increase in demand. Furthermore, staged construction would have afforded an opportunity to observe the actual response of the aquifer to pumping and given valuable information for the timing, location and design of future additions to the system.
The study did not consider the impact of water management on water quality because of complete lack of data. If the maintenance of water quality were the objective of management, the number of wells and their spatial distribution, and the allocation of pumping rates might be significantly different.
Nevertheless it is concluded that water supplies for the study area are adequate in quantity and quality to 2000, and wastewater reuse to augment supplies is not now considered necessary.
Wastewater Treatment The town of Manteo is the only locality in the study area with a wastewater collection system and treatment plant. The sanitary sewer collection system was constructed in 1940 and consists of 15,000 feet of vitrified clay pipe. Infiltration accounts for up to 50% of the treated flow (Von Oesen, 1976). The treatment facility, with a capacity of 0.25 MGD, consists of a contact aeration activated sludge system with chlorination. The sludge produced is stabilized in an anaerobic digestor. The plant was constructed in 1971 on piles in Shallowbag Bay, and discharges its effluent to the Bay. There is no room for enlargement and the plant is operating at capacity.
Many package plants throughout the area discharge their effluents either to the inland waters or have subsurface disposal. These facilities typically consist of an activated sludge unit followed by tertiary filtration and chlorination. These usually provide treatment for hotels, motels, and restaurants. MAP 2-1 NORTHERN STUDY AREA -Water Management in Coastal North Carolina -Dare County, 1979 Areas Favorable for Well Field Development Source: Von Oesen, 1973
PAMLICO SOUND The predominant form of wastewater handling in the area is septic tanks. The septic tank is basically a detention tank in which some of the solids settle, accounting for some BOD removal. The tank also serves as an anaerobic digestor for the settled solids, a process which interferes with sedimentation of the solids. The effluent discharges to leaching or nitrification field by means of open drain file. Disposal is a land application process where some reduction of BOD is accomplished by the soil filter. All soils are not suitable as they may be too tight, quickly "plugging up". Also, a certain depth to the water table is needed to provide sufficient aerated filtering depth. In sections of the complex, the water table my rise to within 4 feet of the ground surface, which does not provide adequate filter depth. Up to 90% of the land in the complex has limitations on septic tank usuage (Von Oesen, 1976). A6 indicated earlier, septic tanks cannot be assumed to be an adequate solution for wastewater disposal throughout the area.
Water Quality A report entitled Report on Status of Sewage Treatment -and Disposal: -Dare County Beaches (February 1973) issuz by the Greenville, Regional Off ice of the N. C. Division of Environmental Management indicated that growths of aquatic vegetation, mainly eurasion watermilfoil, and become a matter of significant concern in Currituck Sound, Buzzard Bay, Kitty Hawk Bay and Colington Creek on Colington Island. The report cautioned that the introduction of more nutrients to these areas would be an undesirable stimulus to aquatic growth. Minor crab kills have occurred in the shallow sections of Kitty Hawk Bay and Colington Creek (Von Oesen, 1976). Since 1973, these areas have been reclassified to prohibit recreational uses. The N. C. Environmental Management Commission report of July 1975 indicated that Roanoke Sound was believed to be "on the verge of exhibiting symptoms of eutrophication" (Von Oesen, 1976). Certain zones within the complex have been degraded by pollutants to the extent that the harvesting of shellfish for marketing has been prohibited by the Office of North Carolina Shellfish Sanitation Program, Division of Health Services.
Shallowbag Bay, which receives the effluent from the town of Manteo, has been officially closed to shellfishing and recreation. Despite this, the Bay is still used extensively for recreational purposes. It is the expressed desire of the local community to upgrade the Bay by removing the hazards associated with its recreational use and to improve water quality to a degree that the present restrictions against shellfish harvesting might be lifted (Von Oesen, 1976).
Wastewater treatment and disposal facilities are inadequate in the Dare County Area. The high water table and poor soils limit the effectiveness of septic tanks and overdevelopment of the area is beginning to show its effects on water quality. Direct contamination of the water supply aquifers is likely as the unconfined aquifer receives the effluents of the septic tank systems and the unconfined and principal aquifers are linked through recharge areas. In addition, the major water source of the Dare Beaches area, Freshwater Pond, is recharged by the unconfined aquifer, Stringent protection of the water resources is needed.
Wastewater Flows The initial design capacity is based on a 20-year design period. The Dare County Beaches area is comprised of Kill Devil Hills, Nags Head, and Whalebone Junction. The water demand is determined by assuming 100 gpcd for permanent and seasonal residents and 25 gpcd for day visitors. Wastewater flows are determined by assuming 80% of the water required will return to the sewer system. The wastewater flow is predominantly domestic with the only major industrial contribution, about 0.5 mgd, coming from the Wanchese Harbor seafood processing plants. It is approximately four times as concentrated as domestic sewage. As this wastewater does not contain chemical or toxic materials, it may be handled with the domestic flow without extensive pretreatment. An equalizing basin would serve to prevent peak loadings at the treatment plant, (See Tables 2-2 and 2-3.)
Disposal Options
The options considered for Dare County are discharge to the inland coastal sounds, to the ocean, and application to land. Coastal Sounds Inland surface water bodies within the area include portions of Currituck Sound, Albemarle Sound, Croatan Sound, and all of Roanoke Sound. Inlets to these water bodies include Kitty Hawk Bay, Buzzard Bay, and Shallowbag Bay. All of the surface water bodies are effluent limited, and thus require secondary treatment as a minimum, with additional treatment based on the "SC" or "SB" classification of water. Roanoke and Croatan Sounds contain valuable shellfish beds and are classified "SA" (shellfish waters) to protect water them. Portions of Albemarle and Croatan Sounds are classified "SB" to protect waters designated for swimming or recreation. Many pockets of water classified "SC" (swamp water) exist in the complex. Map 2-2 identifies the 1978 water quality classifications of the water bodies of the area. Each of these classifications contains specific requirements for wastewater discharges. Regulation 2-79 prohibits wastewater discharges to waters classified "SA". So discharge of effluents can only be made to "SB" and "SC" waters. By further requiring that wastewater be discharged to waters at least 6 feet deep, as recommended by the Division of Environmental Management, discharge to coastal waters is limited to three sites (Von Oesen, 1976). These are: (1) the "SB" waters off of Colington Island; (2) the "SB" waters off of the northwestern tip of Roanoke Island; and (3) the "SC" waters on the lower southwestern shore of Roanoke Island. (See Map 2-3.) These waters are tributary to "SA" waters and must be treated to "SA" water standards. At each of these sites a depth of 8 feet is reached in the distance of 1/2 mile. The depth of 8 feet is chosen to allow a depth of 6 feet above the crown of the effluent pipe. Because the treatment facility at Shallowbag Bay cannot be expanded, and a new site for a treatment facility is required, a more suitable effluent discharge site is selected.
Table 2-2. Northern Area Water ~emands*
Water Demands for Summer Peak (MGD)
Dare Beaches 3.54 4.65 6.40 Manteo Wanchese Total
Water Demands for Winter (MGD)
Dare Beaches Manteo Wanchese Total
* 100 GPCD for permanent and seasonal residents 25 GPCD for day visitors Table 2-3. Northern Area Wastewater ~lows*
Wastewater Flows for Summer Peak (MGD) -1980 -1990 Kill Devil Hills 1.44 1.90
Nags Head 1.02 1,34
Whalebone Junction 0.37 0.48
Manteo 0.28 0.36 Wanchese -0.04 -0.16 Total 3.15 4.24 Industrial Flow -0.5 -0.5 TOTAL 3.65 4.74
Wastewater Flows for Winter (MGD)
Kill Devil Hills Nags Head Whalebone Junction Manteo Wanchese Total Industrial Flow
TOTAL 1.02 1.22
*Wastewater flow is 0.8 times water demand Industrial flow is from Wanchese fish processing plant ATLANTIC OCEAN Q Ocean Discharge
The site selected for the ocean outfall is within the town limits of Nags Head, and is located about one mile south of the Nags Head-Kill Devil Hills Boundary, (Map 2-3, Disposal Location #4.) This location is chosen as it provides for central collection of wastewater from surrounding areas and the slope of the ocean bottom is relatively steep. A summary of ocean depths at various distances from shore at this location is presented in Table 2-4. For outfalls ranging in length from 3,000 to 21,000 feet, the ocean depth increases from 25 to 76 feet. Dilution at the diffuser depends upon ocean depth, with dilution increasing with ocean depth for diffusers that are otherwise identical.
Four wastewater treatment alternatives were examined for use with ocean outfalls at this location. These are: (1) primary treatment alone, (2) primary treatment plus disinfection, (3) secondary treatment alone, and (4) secondary treatment plus disinfection. The base design year was considered to be 1980. A design life of 20 years for the wastewater treatment facilities and for the outfall pipe and diffuser was assumed, so that the end of the design period occurs in 2000. The average daily wastewater flow during the summer period of the year 2000 is estimated to be 6.4 MGD (10 cfs.). This is the design flow for all treatment and disposal facilities. It includes both domestic and industrial contributions.
Table 2-4 Ocean Depth as a Function of Distance From Shore for the Proposed Dare County Outfall
Distance from Shore Ocean Depth (feet) (feet)
Source: National Oceanic and Atmospheric Administration Nautical Charts
Ocean Water Quality. To determine water quality changes due to an outfalldischarge, the existing water quality conditions of the receiving waters must be known. This allows for the establisl-nnent of baseline water quality for measuring the pollution resulting from the ocean discharge. There are very few data on water quality parameters available for the Dare County area. Thus, it is not possible at present to determine reliable baseline levels against which the effects of the wastewater can be measured. However, some effects that can result are qualitatively discussed below. Oxygen depletion could occur from an improperly designed ocean outfall. However, in a well-designed submarine outfall system that achieves 100 to 1 initial dilutions, oxygen is seldom a controlling parameter. For example, if raw sewage with a 5-day BOD of 200 mg/l is discharged through an outfall, the concentration in the mixing zone above the diffuser decreases to about 2 mg/l. Thus, considering the large reservoir of dissolved oxygen normally present in the ocean, there would be no discernible depletion of oxygen. There are exceptions in areas where the oxygen of bottom waters is naturally very low. However, these occurrences are rare and to not appear to be applicable to the ocean off Dare County. The few data that are available on the existing conditions of the ocean near the study area are given in Table 2-5. The location of each of the sample stations is given in Figure 2-2. The dissolved oxygen levels are in excess of 6.0 mg/l and are near saturation at a majority of the stations and depths sampled. The data were collected over a period of only two days. They provide some confirmation for the expectation that the dissolved oxygen levels in this area should be quite satisfactory. Concentrations of nitrogen and phosphorus in domestic wastewaters are typically about 25 mg/l and 10 mg/l, respectively. After dilution, these would be about 0.25 and 0.1 mgll. While such concentrations exceed the background levels presented in Table 2-5, the actual mass inputs of these elements, the product of the sewage flow (10 cfs) and the wastewater effluent concentrations, would be about 1300 lbs/day of nitrogen and 530 lbs/day of phosphorus. The flow of ocean waters through this area is unknown at present but the mass inputs of these elements by natural processes can be expected to be much greater than those from the wastewater discharge. In any event, these nutrients would enrich these waters and tend to improve fishing in the area. There are no data available for fecal coliform concentrations*in these coastal waters. Their concentrations, however, should be very low. Coliforms, and the pathogenic organisms for which they serve as an indicator, are the only potential pollution problem anticipated from ocean outfalls. Protection of the bathing beaches from bacterial pollution is the objective of the treatment and ocean discharge systems presented in this report. Two of the treatment alternatives for the Dare County study area call for chlorination prior to ocean discharge, to provide further reduction of bacteria. However, this chlorination process may be harmful to the ocean ecosystem. Chlorination of effluents high in ammonia and organic matter may * * .+hl .whe~uwm~h+n~0ddd<4COohlCOhlCOCOaohl ehl ~+n0000000+0+*+ . 00 ~oooooooo~~~~~P;~~~ Pa .Pa 0 ddddddddoo 0
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emaoda3+oCO+mmmommhmmm hlumhlhdCOmomhmahlmmhmu+ 0000+0000e0000000000 00000000000000000000 dddddddddddddddddddd
emehOhNaNmdmNhmOhame mmmmemNdamheaemeedom 00000000000000000000 00000000000000000000 dddddddddddddddddddd
IIIII IIIII -- 0' 1 2 3 miles
Figure 2-2, Location of Sampling Stations in Ocean Waters Offshore to Proposed Dare County Outfall
I form chloraines or other chlorinated compounds that are detrimental to marine flora and fauna in the immediate vicinity of the outfall. Furthermore, evidence exists that even low chlorine concentrations can inhibit growth of phytoplankton and zooplankton (Environmental Protection Agency, 1973). However, this phenomenon depends upon exposure time, temperature and other factors.
The outfall for Dare County is to provide substantial initial dilution which minimizes the effects of the chlorination process, Chlorine residuals from domestic wastewater treatment facilities are normally about 1 mg/l. Thus, upon dilution, this concentration diminishes to about 0.01 mg/l and no trace of the chlorine residual should be noticeable except in the sewage plume at the outfall. Concentrations of 0.1 mg/l and above many cause problems to ocean life (Environmental Protection Agency, 1973). A major concern with chlorination is the cost and the energy-intensiveness of chlorine manufacturing.
Physical Ocean Characteristics. Ocean currents have significant effects on the transport and fate of pollutants discharged from ocean outfalls. The direction, duration, and velocity of ocean currents near the diffuser must be known in order to predict the overall dilution of the sewage after discharge. Lacking such knowledge, assumptions must be made concerning current direction, duration and velocity. Few data on ocean currents are available for the Dare County study area. However, some data are available for nearby areas. An ocean outfall is currently being constructed in the Norfolk-Virginia Beach area of Virginia. Current date were collected to predict the ultimate fate of the wastewater from this outfall (Malcolm Pirnie, Inc. Engineers, 1975). Also, there are some current data available for the areas south of Cape Hatteras, North Carolina (Stefansson, et.al., 1971).
The surface waters in Southern Virginia exhibit three recurring net drift patterns. There is a strong southerly drift that occurs for two periods of 5 to 7 days each month. There are also onshore and offshore drifts that last about a week each month. The velocities of these surface water currents vary with direction, The typical velocities for the strong southerly currents are between 0.1 and 0.25 m/s. Values for the onshore and offshore currents are between 0.03 and 0.10 m/s. The bottom waters in Southern Virginia show no distinct recurring net drift patterns. However, during the times of discernible bottom water drift, the current velocities range from 0.005 m/s for southerly currents to 0.06 m/s for onshore and offshore currents.
Near Cape Hatteras, North Carolina, there appears to be a continuation of the southerly currents detected in Virginia. The Virginia waters continue southward to Cape Hatteras and then either enter into the Raleigh Bay, south of Cape Hatteras, or are deflected offshore and disappear into the Gulf Stream. The occurrence of one or the other depends upon the time of year and thus upon the temperature and density gradients in the ocean a that time. Thus, for at least part of the year, the Dare County ocean currents are controlled by the longshore currents originating in Virginia. The North Carolina State University study (1979) determined the local circulation patterns and the magnitude, duration and direction of the ocean currents in the Dare County area. The local currents in the Dare County study area are highly variable. There are some longshore currents present, as discussed above, as well as indications of onshore currents that come into the near shore area at a 45' angle. The near shore area is that area which has a depth of approximately 30 feet or less. This area extends approximately 4000 feet from shore in the Dare County area. Onshore currents that originate in the offshore areas are likely to dissipate in the eddy currents and turbulence of the near shore area. Thus, it it unlikely that onshore currents at Dare County continue directly toward shore in the near shore area.
Due to uncertainty of the currents expected in the study area, and in any event their considerable variation, conservative assumptions have been made. First, it is assumed that the currents come directly into shore so that the time for wastewater dilution by eddy diffusion and also for coliform dieoff is relatively small. The probability of having such direct onshore currents for any extended period of time is low. As noted in the North Carolina State University report (1979)" . . . the worst-case conditions occur very seldom if at all."
A second assumption is that the critical onshore current travels at an average velocity of 7 cmlsec. This assumption is less than maximum onshore current velocity at Virginia Beach, which is 10 cm/s. However, the average onshore current velocity would be less than this maximum onshore current velocity. Hence, the average velocity assumed here is considered to be somewhat high and conservative.
Stratification also is an important factor in the ultimate fate of wastewater discharged to the ocean. When vertical density gradients exist, wastewater rises only to the height where the density of the diluted sewage is equal to the density of the sea water. This height can be designed to occur in the pycnocline, so that the wastewater plume remains submerged and can travel at lower velocities. There are few data available to prove or disprove the existence of stratification in the Dare County study area. It is probable that there is a weak density stratification in the summer. This may be due either to temperature gradients or to meanders in the Gulf Stream (Stefansson, et.al., ' 1971); Von Oesen, 1976). There is little or no stratification in the winter because the Outer Banks shield the relatively high saline ocean waters from the low salinity estuarine and river waters. Thus, no density gradients are formed during that time.
Designs herein, based on the assumption that offshore waters are completely mixed, should provide the most protection for the bathing areas at the Dare County beaches.
Wastewater Treatment and Ocean Disposal Systems. Results of analysis of the performance of the four wastewater treatment and ocean disposal systems considered for the Dare County area are presented in Table 2-6. All of the alternatives are designed to yield predicted concentrations of fecal coliforms at the beaches of less than 200/100 ml, the standard for Class SB waters. Alternative A, primary treatment alone, requires the longest outfall (3.1 miles), while alternative D, secondary treatment plus disinfection, uses the shortest outfall (1.3 miles). Alternatives B and C have different treatment schemes (primary treatment plus disinfection versus secondary alone) but require identical outfall lengths. This is because the coliform concentrations in the effluents from these treatment systems are estimated to be equal, at 8 X lo6 per 100 ml. The details of the procedures used in obtaining these designs are described in the Appendix, Spiegel, 1978). The outfall pipe used for each alternative has a diameter of 22 inches and terminates in a diffuser comprised of 20 ports located at 20-foot spacings. The costs of the four treatment and disposal alternatives are presented in Table 2-7. Ranked in order of increasing costs, the results are (1) primary treatment plus chlorination, (2) primary treatment alone, (3) secondary treatmment plus chlorination, and (4) secondary treatment alone. The costs include the capital costs of all treatment components and of the outfall system, and also the present value of the operation and maintenance costs adjusted to present value in July, 1977 dollars using a discount rate of 6 per cent and a design period of 20 years. Details of the cost analysis are presented in the Appendix. Land Application for Roanoke Island. Sources of wastewater on Roanoke Island during the design period are Manteo, Wanchese and the proposed seafood processing complex at Wanchese Harbor. Flow rates, annual nitrogen and phosphorus loads, and weekly total oxygen demand (TOD) loads are shown in Table 2-8. Although the seafood processing complex contributes only about half of the total flow, it contributes an average of 80% of the total N load because of the high N content (90 mg/l) of the wastewater. (See Table 2-9.) Nitrogen and phosphorus contributed by Wanchese and Manteo are calculated using typical N and P concentrations for secondary effluent (25 and 10 mg/l respectively). However, the processing complex load is calculated using estimates of N and P concentrations for untreated wastewater from the area. If N and P concentrations are reduced during pretreatment, actual N and P loads will be somewhat lower than those shown in Table 2-8. In estimating the actual N load it is assumed that 10% of the N in the seafood processing wastewater will be lost during pretreatment and ammonia volatilization durfng irrigation. For the design year 2000 the total N load would be 157,000 lbs N/yr. At an application rate of 600 lb N/acre/yr for Coastal bermudagrass overseed with rye in the fall, 262 acres will be required. Using this amount of irrigated land, other loading rates of concern would be: Table 2-6. Effectiveness of Treatment and Ocean Disposal Alternatives for Dare County Area.
Effluent Coliform Reductions by Dilution Coliform Outfall and Dieoff in the ocean* Predicted Treatment Conc. Length Discharge Initial La t era1 Beach Area Alternative (per 100 ml) (miles) Depth (ft) Dilution Dispersion ~ieoff*" Conc. (per 100 ml)
A Primary Treatment 8 X lo7 3.1 73 108
B Primary Treatment 8 X lo6 Plus Disinfection
C Secondary Treatment
D Secondary Treatment Plus Disinfection 8 X lo5 1.3 48 67
"Reduction Factor = Coliform cone. before dilution or dieof f/coliform conc. after dilution or dieof f . **Dieoff based on tgo = 9 hours.
Source: (Spiegel, 1978) Table 2-7. Cost of Treatment and Ocean Disposal Alternatives for Dare County Area
Treatment Outfall Capital Costs Present Value, O&M Total Cost Alternative Length (Miles) ($ x lo6) Costs ($ X lo6) ($ x lo6) A
, Primary Treatment 3.1
B Primary Treatment Plus Chlorination 2.1
C Secondary Treatment 2.1
D Secondary Treatment Plus Chlorination 1.3
Design Flow = 6.3 MGD Table 2-8. Wastewater Characteristics for Roanoke Island.
Manteo Total Weighted Seafood Weighted Parameter summer1/- Winter mean Wanchese Processing Summer Winter mean
Flow, mgd 1980 0.27 0.06 1990 0.36 0.08 2000 0.47 0.11
Total N~/,lb/yr 1980 - 6,900 3,000 1990 9,200 4,000 2000 12,000 5,600
IU I Total p3/, Ib/yr IU ul 1980 - 2,800 1,200 1990 3,700 1,600 2000 4,800 2,200
Total oxygen demand4/, lb/wk 1980 975 450 1990 1,300 600 2000 1,700 800
-11 Summer: (May 15-Sept. 15) 123 days; winter 242 days.
-21 N concentrations: Municipal effluent 25 mg/l; seafood processing effluent 90 mg/l. 31 P concentrations: Municipal effluent 10 mg/l ; seafood processing effluent 14 mg/l.
-41 TOD concentrations: Municipal effluent 185 mg/l; seafood processing effluent 370 mg/l.
-51 N load assuming a 10% loss of N from the seafood processing wastewater due to pretreatment and NH3 volatilization. Table 2-9. Industrial Wastewater Flow and Characteristics
Wanchese Harbor Project
FLOW (GPD. ,1 -BOD SUSPENDED SOLIDS TOTAL NITROGENC MAX. MAX. MAX. (AVG .) (MAX) MG/L LBS/DAY MG /L LB S /DAY MG /L LBS /DAY I. Blue Crab Processing
11. Scallop Freezing
111. Shrimp Freezing
IV. Finfish Processing
N I N V. Fish Unloading m VI. Fish Meal Processing
VII, Cleaning & Sanitizing Holds
TOTALS
Avg. 794 mg/l Avg. 964 mg/l Avg. 88.6 mg/l
tes: a/ Based on 8-hour working day, 6 trawlers/hour @ 2,000 gallons of effluent generated per trawler. - Based on 12-hour working day, 6 trawlerslhour @ 2,000 gallons of effluent generated per trawler. -C/ Included organic nitrogen and ammonia nitrogen. Source: Von Oesen, 1976. P 34,700 lb/yr/262 acres = 132 lb/acre/yr TOD 14,200 lb/wk/262 acres = 54 lb/acre/wk Maximum hydraulic load (summer)
1.18 x lo6 gal/day x 7 days/wk 262 acres x 27,200 gal/acre-in = 1.16 in/wk
At 600 lb N/acre, the TOD and hydraulic loading rates are well within allowable limits. The acceptability of the P loading rate depends on the P fixation capacity of the soil on the application sites.
Soils. On Roanoke Island there are two well-drained soils that are suitable for land application sites. These are Bayrneade fine sand (loamy, siliceous, thermic, Arenic Hapludults) and Kureb fine sand (siliceous, thermic, uncoated, Spodic Quartzipsamments). Onslow fine sand (fine-loamy, siliceous, thermic Spodic Paleudults) is also suitable if artificial drainage is installed. (For a detailed description of these soils, see Appendix.) Current laboratory studies with Baymeade and Kureb soil from Roanoke Island indicate that these soils have a considerable capacity to fix P. Daily additions of 10 ppm P solutions to samples of these soils have added 95 ppm of P (soil weight basis) and to date no P has been found in leachate from the samples (King, 1978). This retention is equivalent to about 1600 lbs. of P/acre in a 4 ft deep soil volume. The P application rate to supply 132 lb/acre/yr in 2000 would apply an average of 95 lb P/acre/yr so a net of 1300 lb P/acre would be applied during the design life of the site. The predicted P fixation capacity from the laboratory study is conservative because of the short time period between applications. Thus, it appears that these soils will adequately handle the P loading rate. The higher clay content of the Onslow soil indicates that it has a greater fixation capacity than Baymeade and Kureb.
Sites. The first criterion used in selecting potential sites on the island is soil type. After suitable areas are identified, sub-areas which could serve as multiple use sites are identified, i.e., sites which could be used for a land application system without drastically altering the present site use. The county-owned airport is considered as a potential multiple use site (Figure 2-3). There are 147 irrigable acres on the property and an additional 17 acres not suitable for irrigation where a storage lagoon could be constructed. As the land between and around the runways must be maintained in low growing vegetation, the area could be irrigated to produce a hay crop with little effect on airport operation.
The savings in land cost at the airport are substantial. Investigation of other sites on the island show that, in addition to the useable area that must be purchased, an additional 43% must be purchased to allow a 100 ft. buffer strip between irrigation fields or storage lagoons and adjacent land. Thus, the 164 acres of useable land at the airport would be equivalant to 234 acres if the site had to be purchased. At $5000 per acre use of the airport would save $1,171,000 in land costs. Additional land would be required to handle the entire waste load. An additional 43 acres adjacent to the airport could be purchased to supply 33 acres of land for irrigation and 5 additional acres for pretreatment and storage. A 163-acre purchase along Highway 641264 just east of the bridge to the mainland would provide three fields totaling 123 acres of irrigatable land (Figure 2-3). The total irrigable acreage of these sites would be 303 acres and would be sufficient to handle the N load through 2025 at 558 lb. N/acre/yr.
Land Application on the Dare Beaches. Flow rates, annual nitrogen and phosphorus rates, and weekly TOD loads for the Dare Beaches are shown in Table 2-10. The table also includes the flow and characteristics of the wastewater that would result from combining the flows from Roanoke Island and the Dare Beaches. During the 1980-2000 design period, the weighted mean flow from the Dare Beaches is estimated to increase about 77% and the nutrient and TOD loads would increase correspondingly.
Soils. Two soils are considered for application sites: Newhan fine sand (mixed thermic Typic Udipsamment) and Duneland (unclassified blowing sand). A typical Newhan profile consists: 0 - 2 inches - grayish brown fine sand; 2 - 50 inches - light gray fine sand; 50 + inches - light gray sands. Calcareous shell fragments, mostly of sand size, make up 5 to 25% of the soil mass. Duneland is very similar to Newhan except that it lacks vegetative cover and is therefore subject to wind erosion. Both soils have a permeability of > 20 incheslhr but are droughty due to their low water holding capacity.
As these soils contain very little iron and aluminum, P fixation by formation of iron and aluminum phosphates will be relatively low. Current laboratory studies with Newhan and Duneland soils indicate some P fixation capacity, probably a result of P reacting with calcium in the shell fragments to form Ca3(PO4)2 (L. D. King, 1978). Insufficient data have been collected to estimate a P fixing capacity for these soils,
If an effluent application rate is chosen that applies 70 lb Placrelyr in 1980 and increases to apply 150 lb P/acre/yr by 2000, a total of 2200 lb P/acre will be applied during the 20-year design period. Crop harvest would remove 30 lb Placrelyr so the net application would be 1600 lb P/acre during the design period. Some of this would be retained by the soil and the rest would eventually move into the ocean and the sound. However, the P removal efficiency of land application is still superior to that of secondary treatment and sand filtration.
Table 2-10. Estimated Wastewater Characteristics for Dare County Study Area
Roanoke Island Dare Beaches + Dare Beaches
Weighted Weightedw Parameter Summer Winter &an Summer Winter Mean
Flow, mgd 1980 2.88 0.24
Total N, 1blyrl/- 1980 73,000 12,000
Total P, ~b/~r~/- 1980 29,000 4,800
Total oxygen demand, lb/wk 1980 10,200 1,700
Total N load is based on 25 mg/l for Dare Beaches, For the combination of Roanoke and Dare the concentrations are: 1980, 25 mg/l; 1990, 38 mg/l; 2000, 36 mg/l; -21 Total P load is based on 10 mg/l P for Dare Beaches, For the combination of Roanoke and Dare the concentrations are: 1980, 10 mg/l; 1990, 11 mg/l; 2000, 11 mgll; Sites. Three multiple use sites are identified: P
Wright Brothers National Memorial (WB) 90 acres Sea Scape golf course (ss) 81 acres Duck Woods golf course (Dm 91 acres
Other proposed sites devoted solely to effluent irrigation are:
Kitty Hawk 1 (KH1) 260 acres Kitty Hawk 2 (KH2) 35 acres Intersection (INT) 88 acres Duck (DUCK) 215 acres
General locations are shown in Map 2-4. Specific locations are shown in Figure 2-4.
Loading Rates. At a 600-lb ~/acre/yrloading rate for Coastal bermudagrass and rye, 273 acres would be required for the 2000 design flow, However, because of the annual fluctuation in flow, most of this N &st be applied during the 4-month summer period. The hydraulic loading rate in the summer would be:
5,12 x lo6 gallday x 7 days/wk = 4.8 in/wk 27,200 gallacre in x 273 acres
The soils on the application sites could easily accept this hydraulic load. However, as these soils have a low water-holding capacity the residence time of the effluent in the soil would be low at this application rate.
Three alternatives may be considered:
(a) Irrigate 2.0 in. every third day. This would wet the upper 2 to 3 ft of the soil and allow 2 days between applications for treatment to occur in the soil. (b) Increase the irrigated acreage in the summer to reduce the hydraulic loading rate. (c) Store some of the summer flow so it could be irrigated during the fall and spring and thereby reduce the hydraulic loading rate in the summer.
Alternative (a) would be the cost effective option. The KH1 and KH2 sites together contain 295 acres and use of this area would result in a hydraulic loading rate of 4.4 in/wk (1.9 in. applied every third day). PAMLiCO SOUND ~@i< Kitty 'Hawk Site 1
Kitty Hawk Site 2
Golf Course Site
FIGURE 2-4. Land Application Sites and Soil Series on the Outer Banks Curri t uck Sound Atlantic Ocean
Duck Site
FIGURE 2-4 (Continued). Land Application Sites and Soil Series on the Outer Banks Alternative (b) could be accomplished by adding sites WB, SS and DW during the summer. This would add 262 acres and reduce the hydraulic loading rate to 2.4 in/wk. As no crop is removed from these sites, the irrigation rate should be held to a value that would apply a maximum of 200 lb ~/acre/~r* or 2 in/wk for the 123-day period. Thus these sites would receive 2 in/wk while KH1 and KH2 would receive 2.6 in/wk.
Alternative (c) could be accomplished by adding additional storage capacity to bring the total to 18 weeks of storage at the summer flow rate. The cost of these three alternatives are: (a) KH1 + KH2 4,790,000 (b) KH1 + KH2 fulltime WB + SS + DW smmer 6,937,000 (c) KH1 + KH2 + 4,790,000 18 weeks storage
(Costs based on treatment facility at Nags Head) Alternative (c) can be rejected due to cost. Alternative (b) is 46% more expensive than (a) but it has the advantage of not only increasing residence time by lowering the hydraulic loading rate but also lowering the P loading rate. This is the option that is used for the beach area. If WB, SS and DW were not available then Duck could be added to KH1 and KH2 to give an application rate of 2.6 in/wk at a total cost of $8,900,000. Land Application on Dare Beach and Roanoke Island Combined Wastewater characteristics from the combined flows from Dare Beach and Roanoke Island are shown in Table 2-10. Addition of Roanoke Island increases mean flow by 43%. Loading Rates. The best site option for the combined flows is KH1 + KH2 + IWT+DUCK. Use of these 590 acres results in loading rates (increasing from 1980 to 2000) of:
Wastewater Collection
A total of 25 different regional plans for an interceptor sewer system were selected for study in this report, each developed to serve a specific configuration of points of disposal and their associated treatment facilities. Figure 2-5 shows the various configurations schematically.
* The fertilizer recommendation for intensively managed lawns in North Carolina includes 300 lb N/acre/yr and 52 lb P/acre/yr. Service Areas The interceptor system is the link between the local collection systems and the treatment plant. The interceptor is a single pipe from one end of the service area to the other. The service areas are defined as in the Dare County -201 Complex Study (Von Oesen, 1976) and each is served by a pipeline through its entire length. (See Map 2-5) Wastewater treatment plants are located to represent a general location rather than a specific site. The respresentation of a plant near the center of Manteo, for example, does not imply that the plant will be at that specific site but rather somewhere within the town limits of Manteo. Such location is adequate for cost studies. The specific siting of the plant depends on the elevations of tides, storms and floods, ground elevations, zoning, foundations, and many other design considerations.
Interce~torSewer Svstem Plans As there are five towns and six locations for effluent discharge, the number of options is large. However, specific local conditions decrease the number of plans considered to a total of 25. The following assumptions are made : 1) Whalebone Junction cannot treat and dispose of its own wastewaters because of the absence of discharge sites. This area is too small to support an ocean outfall, cannot discharge to the coastal sounds because of shellfishing areas and shallow depths of water, and cannot support a land or wetland application system. 2) The ocean outfall needs to serve at least the three towns of the Outer Banks to be economically justifiable. 3) Where wastewaters from Roanoke Island are to be transported to the barrier island, as the pipeline from Wanchese must pass through Manteo, the flows from Wanchese and Manteo are considered together. Design Assumptions. Four design assumptions were made:
1) Roanoke Island and the Outer Banks have no significant changes in elevation, and are treated as if they are flat, 2) The population is distributed over the area in such a manner that the tributary load to the sewer is uniform. 3) All areas within the designated 201 study service areas are sewered. 4) The bridges of the complex are structurally sound and able to support a pipe line.
The assumption of a uniform tributary load of wastewater is justified both by the shape of the islands and by the fact that most development in coastal regions is of the strip development type, along main roads, This assumption allows pipes to be sized by the length of island they serve. Peaking factors vary from 2.5 where only a town itself is considered, to 2.0 for Kill Devil Hills and 1.5 for the regional system as a whole. Figure 2-5. Schematic for Treatment and Disposal A1 ternatives
PLAN 1 PLAN 2
PLAN 3 PLAN 4
KD H NH WBJ
KEY :
KDH - Kill Devil Hills Treatment Facility NH - Nags Head Coastal Waters WBJ - Whalebone Junction Land Appl ication M - Manteo Ocean Discharge W - Wanchese 0 Wetland Appl ication 0-Community PLAN 5 PLAN 6 KDH N H WB J KDH
PLAN 7 PLAN 8
KDH N H WBJ
PLAN 9 PLAN 10 KD H NH WB J PLAN 11 NH WB J
PLAN 13 PLAN 14
WH WBJ KDH N H WBJ
PLAN 15 PLAN 16 - PLAN 17 PLAN 18 KDH NH WB J KD H N H WB J
PLAN 19 PLAN 20
KDH NH WB J KDH NH WB J
PLAN 21 PLAN '22
KDH NH WB J PLAN 23 PLAN 24
KDH NH WB J
PLAN 25
KDH b NH WB J MAP 2-5 NORTHERN STUDY AREA -Water Management in Coastal North Carolina -Dare County, 1979 --- Service Area Boundaries 0 Wastewater Treatment Facilities Locations m Interceptor Sewer Route (Not to scale) Source: Von Oesen, 1976 ALBEMARLE SOUND
ATLANTIC OCEAN
CROATAN SOUND
ROANOKE MARSHES
SCALE IN MILES 101234 The assumption of providing sewer service to the entire study area implies that an interceptor pipe will run from one end of each service area to the other, regardless of the density of the population in that area, excluding the areas of Kitty Hawk, Southern Shores and Sound Landing. This is most important in the outlying areas where the population densities are low.
In Roanoke Sound, a swing bridge is encountered, and the pipe must be subaqueous to a depth great enough to clear a dredged channel. On the remainder of the bridge the pipe may be hung. Another occasion where the pipe crosses water is when the interceptor sewer crosses to Colington Island. In this application the water is one foot deep and the span is about a tenth of a mile.
The water table is about 6 feet below the ground surface during most of the year and may rise to within 4 feet of the ground surface in the spring. This means that the interceptor sewer line is almost entirely under water most of the year. To prevent high infiltration, the joints must be secure and watertight and the pipe and joint materials, and methods of construction must be carefully selected.
Results. A summary of the results of the various sewerage system layouts is shown in Table 2-11. (Details of each plan are in the Appendix.) The costs are within the range of 16 to 23 million for the options of discharge to the oceans and land application.
In general the lower sewerage system costs all involve options that include an ocean outfall for all or part of the flow. This is because the treatment facility at Nags Head is the most centralized and the pipe diameters to transport the wastewater to the facility are smallest. When the outfall is limited to serving the Outer Banks, and Roanoke Island is served separately, the lowest sewerage system cost is incurred. For an equal length of pipe run, the smaller diameter pipes require a larger number of pump stations. However, the cost is more sensitive to pipe diameter than to number of pump stations.
These costs are only for the sewerage system, and the treatment is included in the next section.
Wastewater Treatment
Treatment systems are considered individually for each disposal option as each disposal mode has its own treatment requirements.
Coastal Sounds. Effluent discharge into the coastal sounds is limited to waters having an "SB", bathing and recreation, or "SC", swamp water, classification. However, in each of these cases the waters are tributary to shellfishing areas and must be treated to the "SA" standards. Conventional activated sludge treatment followed by sand filtration and chlorination is adopted for such waters. Sand filtration is required to meet the total suspended solids limit. An in-plant pumping facility is included ahead of this unit. Table 2-11. Northern Area Interceptor System Costs
Effluent* Capital Costs P.V. O+M Costs Total Cost Plan Disposal ($ millions) ($ millions) ($ millions)
*CW = Coastal Waters W = Wetlands 0 = Ocean L = Land "SB" waters require "dual chlorination", that is incorporation of standby chlorination facilities. Sludge is handled by anaerobic digestion followed by drying beds and hauling of the dried sludge to a landfill. No attempt is made --YO remove nutrients as results of modeling by the Water Quality Division of the Division of Environmental Management show that the waters do not require nutrient removal (McGhee, 1978). The treatment requirements are summarized below: SC Waters (Tributary to SA waters) BOD - 30 mg/l Suspended Solids - 15 mg/l Total coliform - 70/100 ml PH - 6-9 SB Waters (Tributary to SA waters) Same Requirements + Dual Chlorination Processes Preliminary Treatment Chlorination Primary Treatment Anaerobic Digestion Conventional Activated Sludge Drying Beds and Sand Filtration Hauling Sludge to landfill Ocean Discharge. The waters of the Atlantic Ocean off of the Outer Banks are classified as "SB" for bathing and recreation, and "SB" standards must be maintained. This is mainly applicable in the coliform bacteria concentration limits for the beaches. As noted earlier, four treatment modes are studied: primary and secondary treatment with and without chlorination, A conventional activated sludge process is used for cost estimates if secondary treatment is included prior to discharge. Sludge is treated anaerobically, digested, and dewatered on drying beds, with the sludge hauled to a landfill. Land Application. Prior to land application the wastewater receives preliminary treatment, stablization in an aerated lagoon and chlorination. In order to study the effect of location of the treatment facility on a land application system, the analysis is made based on locating the facility at both Kitty Hawk and at Nags Head.
Until additional data are available on the phosphorous-fixing capacity of Newhan and Duneland soils on the Outer Banks, it is not possible to predict whether P removal is required prior to land application. To be conservative P removal facilities are included in the pretreatment system to reduct the P to 5 rng/l. As the 0.5 mgd flow from the seafood processing complex has a BOD5 that is four times that of domestic sewage, it is assumed that this flow is equivalent to 2 mgd of domestic sewage. This may result in a conservative design of the lagoon as BOD removal per se is not necessary prior to land application.
From the standpoint of hydraulic loading rate, soils on the proposed sites could be irrigated during wet periods without danger of runoff, However, the residence time (and therefore treatment efficiency) would be reduced due to the additional hydraulic load imposed by rainfall. On Roanoke Island a lagoon sized to hold 30 days of summer flow is used while on the Outer Banks, a lagoon sized to 15 days of summer flow is adequate. The higher permeability of the soils on the Outer Banks allows a shorter storage time. These lagoons will be used to store treated effluent during wet periods or during extremely cold periods. As the lagoons are sized for a period of peak summer flow, the storage time available in the winter is much greater than the required period. No sludge handling is necessary when an aerated lagoon is used, as the settled sludge is continuously being stabilized on the bottom of the lagoon. It may be necessary to purge the system of stabilized sludge every few years.
Wetland Application. As the Roanoke marshes are tributary to the "SA" shellfishing waters of Croatan Sound, effluent must be treated to "SA" standards. The wetlands would serve as an advanced wastewater process, and thus provide the same function as a sand or tertiary filter. Thus by the time the effluent reaches the waters of Croatan Sound, they will be treated to "SA" standards. A conventional activated sludge system is used with conventional chlorination and sludge is handled by anaerobic digestion and drying beds with the dried sludge being hauled to a landfill. However because so little data are available concerning the capacity of the wetlands, and because in this instance the wetlands are so far distant from the centers of population, this option is not fully explored.
Results. Table 2-12 shows the cost for the treatment options, with details in the Appendix. These results are not directly comparable as different modes of treatment are being used as a result of using a variety of disposal schemes. In general, treatment costs before discharge to the ocean are lowest as filtering and nutrient removal are not required. The aerated lagoon of the land application disposal mode is also low in cost as separate sludge handling is not necessary. Disposal to "SC" rather than "SB" water does not show an economic advantage as the costs for plans 7 and 8 are equal. Regionalization, or the use of the least number of treatment facilities, produces the most cost-effective options as economies of scale are involved. This is shown by plans 7, 8, and 15, which are the regional plans for three treatment modes. However, the treatment costs are only a part of the total costs of the sewerage-treatment-disposal system.
Effluent Disposal
This section summarizes the design of the outfall lines into the sounds and ocean, and the application systems for land disposal. Results are summarized on Table 2-13, with details in the Appendix. Table 2-12. Northern Area Treatment Costs
Effluent Capital Cost P.V. OfM Cost Total Cost Plan Disposal ($ millions) ($ millions) ($ millions)
*FO~ocean disposal, primary treatment with chlorination is the basis for costs. Costs of the other options are shown in Table 2-7. Coastal Sounds. Effluent discharge in the sounds is obtained by a force main used as an outfall, terminating when the water depth reaches 8 feet. There is no diffuser section. peaking factors used on the effluent lines are the same as those on the interceptor lines. The pump station and force main is sized to operate at a minimum velocity of 4 ft/sec. The length of the subaqueous section is approximately 1/2 mile at all three disposal sites. Ocean Discharge. The length of an outfall required to achieve a certain coliform level decreases with an increase in the degree of treatment achieved before discharge. The length of the outfalls, including the diffuser sections, as determined by the preliminary design are:
16000 ft for primary treatment without chlorination 11000 ft for primary treatment with chlorination 11000 ft for secondary treatment without chlorination; and 7000 ft for secondary treatment with chloriation. Each of these costs include the pumping station; a gravity line from the ocean to the pump station wet well, which will allow flushing of the outfall during periods of low wastewater flow; a section of force main from the pump station to the subaqueous outfall line; the subsequent outfall; and the diffuser. Land Application. Land application is accomplished by sprinkler irrigation. Effluent is pumped from the treatment facility to the disposal sites where it is stored and applied to the fields. Some of the irrigation sites, such as the golf courses, can only be irrigated at night. Force mains are operated at 4 ft/sec minimum velocity and sprinklers are of either the center pivot or solid set type depending on the shape of the site. The effluent irrigation cost represents the costs for high-lift pumping, force mains, land, site preparation, the irrigation system, monitoring wells, fences, and are adjusted for the benefits to be derived from crop production.
As the increase in wastewater flow from the year 2000 to 2025 is small, the capital cost estimates for the irrigation sites on Roanoke Island are based on the 2025 flow being applied to the 303 acres of land. Present value of operation and maintenance costs are for the design period 1980 through 2000. Results In general, for the disposal element of each system, land application is most costly, followed by ocean discharge and then discharge to the coastal sounds. The land application mode requires a large amount of land to be purchased, and an elaborate sprinkler irrigation system to be set up. The ocean discharge mode requires pump station, outfall pipe and diffuser. The total costs for each plan are presented in the next section. Table 2-13. Effluent Disposal Costs
Effluent* Capital Cost P.V. OfM Cost Total Cost Plan Disposal ($ millions) ($ millions)*** ($ millions)
* CW = Coastal Waters W = Wetland 0 = Ocean L = Land he he outfall here assumes that treatment for ocean disposal is primary sedimentation plus chlorination. The costs for other outfall designs are summarized in Table 2-7.
***~e~ativevalues arise from income produced from crop production in land disposal. This section includes an economic comparison of the various options. However, cost effectiveness is not the sole criterion for selecting the most appropriate option. The impact on the receiving waters and the environmental integrity of the area are considered later. A table of the final dollar cost of each regional plan is presented in Table 2-14 with more detail in the Appendix. The least costly system for ocean disposal is primary treatment with chlorination, and that mode is used in all comparisons. The least costly plans are 15B and 25B. Plan 15B is a comprehensive regional system, with all wastewater in the area being collected for disposal in the ocean. Plan 25B serves Roanoke Island and the Outer Banks separately, with Roanoke Island using a land application system while the Outer Banks uses ocean disposal. Options that do not include ocean disposal are 20 to 40% more costly than the least cost options. Options that include some disposal to coastal waters with ocean disposal are about 10% greater than the least cost options.
Inasmuch as disposal ' to the ocean and to the land is more environmentally acceptable than disposal to the coastal sounds these options would be more attractive even if the costs were no lower. The fact that the lowest cost options are also the most environmentally acceptable urges a conclusion that wastewater management in the Dare County area should include ocean disposal for all the wastewaters generated in the communities on the Outer Banks. Wastewaters generated on Roanoke Island should be handled either by land disposal on the island or by integration with the ocean disposal system provided for the Outer Banks. Thus systems that would stop discharges to the fragile inland coastal waters and offer the prospect of reclaiming and preserving shellfish growing areas are less costly or at worst of the same order of cost as systems that discharge to these waters. Plan 15B--the comprehensive regional system--balances all the considerations as well or better than any of the others and is the recommended approach, Table 2-14. Total Costs of Alternatives
Effluent* Capital Cost P.V. O+M Cost Total Cost Plan Disposal ($ millions) ($ millions) ($ millions)
*CW = Coastal Waters 0 = Ocean W = Wetland L = Land
**Based on ocean disposal preceded by primary treatment and chlorination. Other options are listed in Table 2-7. MAP 2-6 NORTHERN STUDY AREA -Water Management in Coastal North Carolina -Dare County , 1979
Plan 15 Chapter 111
WASTEWATER MANAGEMENT IN THE
SOUTHERN (CARTERET-ONSLOW COUNTY) COASTAL AREA
The Carteret County-Onslow County area is centrally located on the coast of North Carolina. Its area is endowed with abundant natural and economic resources. Approximately three-fourths of the area is surrounded by water and its highly productive estuarine systems contribute substantially to the marine fisheries of the State of North Carolina and the nation. It contains a major deep water port which makes it a center of commerce. Its southerly-oriented beaches are among the most beautiful on the entire east coast and are a focal point for a rapidly expanding tourist industry.
All of these factors have contributed to the rapid growth rate experienced recently, and an even more rapid rate of expansion can be expected in the future. The influx of people to the beach areas and the existing communities, and rapid establishment of new communities and residential areas throughout the county have begun to create problems in the provision of adequate water and sewer facilities to serve the rapidly expanding population.
The low-lying land and high water table in this section sf the coastal region increase the problems of providing adequate water supply and wastewater collection and disposal services. Public health and sanitation are now being adversely affected by the lack of wastewater collection facilities and inefficient treatment systems. While septic tank disposal methods are adequate in some instances, many that are in use are located in areas that are too densely populated, and in poor soils. These conditions result in contamination of popular bathing and recreational areas and pollution of highly productive marine fisheries resources in the adjacent streams and estuarines. Where wastewater collection and treatment facilities do exist, the degree of treatment provided is, in some instances, not adequate to maintain established water quality requirements. (Von Oesen, 1970)
The study area is comprised of Carteret County and a section of Onslow County, and encompasses two "201 Study" planning areas; the Carteret County Complex 201 Faci1i.t~Plan and the Swansboro Area 201. Facility Plan. The complex faces the North River on the East, the Atlantic Ocean on the South, and contains the White Oak River and Queens Creek on the West. (See Map 1-2). It includes the towns of Atlantic Beach, Pine Knoll Shores, Indian ~each/ Salterpath and Emerald Isle on the Bogue Banks, and Swansboro, Cape Carteret, Newport, Morehead City and Beaufort on the mainland. The barrier island of the Bogue Banks comprises the entire oceanfront portion of the complex and is separated from the mainland by Bogue Sound. Bogue Sound varies from 0.75 to 2.5 miles in width and is dotted with many "dredge spoil" islands. Two highway bridges connect the island to the mainland: the Morehead City/ Atlantic Beach bridge on the east, and the Cape Carteret/Emerald Isle Bridge on the west. The topography of the mainland portion of the complex is essentially flat with elevations ranging from 5 to 50 feet, and with land slope in a generally eastward direction of about 3 feet per mile. Streams have cut through the coastal plain in several places and are bordered by terraces of various widths that are generally below the level of the coastal plain.
The topography of the Bogue Banks island typifies a barrier island. The prominent features of the island include sand dunes up to 35 feet in height and low lying maritime forests in the undeveloped sections of the island. The mainland side of the island borders on extensive salt marshes. Recent studies have shown that the Rogue Banks are slowly retreating toward the mainland. The erosion rate of the dune line since 1939 is averaging 5 feet per year over the entire island, with most erosion occurring adjacent to the inlets. Storms have been cited as the principal cause of the erosion. However, sand erosion is a natural occurrence, a part of the normal long-term dynamic. erosion/ accretion process of migration of the barrier islands.
Precipitation and Flood Potential
Precipitation is abundant in the area, averaging about 52 inches per year. The average rainfall is about 3 in. per month for most months, and about twice that in mid-summer when evaporation and growing vegetation use the most water. Winter rains are usually associated with large migrant low pressure storms; these usually cause widely distributed rainfall, affecting the interior and the coast to the same degree. The rainfall in summer often results from afternoon and evening thunderstorms, and may be variable from place to place within the county. When heavy rain occurs in autumn it may be caused by off-shore tropical storms. These may be accompanied by windy weather and rough seas; once in several years, on the average, one may come close enough to cause beach erosion and damaging winds.
It is estimated from Weather Bureau data that rainfall in excess of one inch per day occurs an average of fifteen days during the year. Most of these one-inch rainfalls are presumed to occur during the summer months, when rainfall often results from thunderstorms and tends to be of high intensity and short duration and in concentrated areas. Tn contrast, winter rainfalls are usually steady, slow and well distributed. Tropical storms during the late summer and autumn months sometimes result in heavy rainfall, but severe damage is usually limited to the Outer Banks, which provide a barrier against the intense storms.
Some 65 major tropical storms have hit Worth Carolina in this century. The first well-documented hurricane to strike the area, on August 19, 1879, caused considerable damage. The September 16, 1933 hurricane caused the death of twenty persons and formed Bardens Inlet between Core Banks and Shackleford Banks. Damage on Bogue Banks was limited because of sparse development at that time. Since 1950, eight hurricanes have passed by or over the area. The effects of these storms are summarized Table 3-1. The main effect of precipitation of interest for this report is the flood potential, Facilities must not be constructed in areas suspectible to flooding without adequate provision against these floods. These areas of concern would be established by the 100-year base Elood elevation, tidal surges in the sound, and overwash potential on the Bogue Banks. The most recent analysis of flooding potential has been prepared by the Corps of Engineers for the Federal Insurance Administration (Dept. of Housing and Urban Development) associated with that agency's Flood Insurance Program. That report indicates that the existing wastewater treatment facility sites of Morehead City, Beaufort, and Swansboro are not highly vulnerable to the predicted 100-year flood level, while the treatment facility site of the town of Newport is subject to flooding during severe storms. The flood and overwash potential for the Rogue Banks is shown on Figure 3-1. From this figure, the major section of the Bogue Banks is listed as "Overwash Not Evident", the existing dune system being sufficient protection for most of the island. More vulnerable areas exist near the western tip of the island adjacent to Bogue Inlet, and to the east in the vicinity of Salterpath. The tidal surges in Bogue Sound are also of concern. Much of the area of Bogue Banks is designated on "area of minimal flood hazard" in the Corps, report.
Flood planning for a wastewater treatment facility is concerned with mainly the protection of mechanical equipment and the structural soundness of the plant itself. Should an over-loading or overwash of a facility occur, it would be during a major storm when the water quantity available for dilution would be a maximum. Structures should not be constructed where a potential for flooding or overwash occurs unless protection is provided in the design.
Economy and Major Employment-Generating Activities.-
The economy of the Onslow County Portion of the Complex is based mainly around support facilities for the Camp Lejeune Marine Corps Base, followed by the commercial fishing industry and, to some extent, boat building. The fishing industry in Onslow County experienced an increase in revenue of 139% between 1968 and 1973. Potential investors have expressed interest in processing seafood, especially fin-fish, in North Carolina. Swansboro offers excellent potential in thls regard due to its advantageous location.
The economy of Carteret County is based primarily on tourism and related support facilities and on commercial fishing. Carteret County is a major fishing center in North Carolina with a 1973 landing representing 45.2% of the statewide landings and 41.3% of the statewide exvessel landing value. The county enjoys a thriving tourist trade at its beaches. Fort Macon State Park has the largest annual number of visitors of any state park. The nearness of the Gulf Stream, which is only 23 miles east from Cape Lookout, makes this area excellent for all types of fishing. Morehead City, with its excellent harbor, encourages development for ocean commerce and related industry.
Present agricultural development within Carteret County shows a total of about 400 farms occupying 12 % of the land area. This is centered around the Newport and North River areas. The factor that will continue to affect the Table 3-1. Effects of Tropical Storms on Bogue Banks, North Carolina
Storm Tide at Atlantic Beach, Estimated Storm Passage Storm Bogue Banks Bogue Banks Relative to Date Name (feet above MLW) Damage Is land
81 13/54 Barbara NA N A seaward
8130154 Carol NA NA seaward
10/15/54 Hazel 9. O* $2,198,000 inland
8112/55 Connie 5.3 120,000 seaward
8/17/55 Diane 6.2 470,000 inland
9/19/55 Ione 9.0* 132,000 inland
9/12/58 Helene NA seaward
9/11/60 Donna $1,600,000 inland
NA = Data not Available
*Estimated by U. S. Army Corps of Engineers
Source: Von Oesen and Freeman, 1975. JACKSONVILLE (D
- - -. -- wA OVERWASH NOT EVIDENT WILMI NGTON
NOME RECENT
FIGURE 3-1, Chart i l l ustrates overwash 'in->ensit\; between Cape Lookout and Cape Fear. The wrist bguc Panks segment 04 fhe piarming area generally shows no evidence of overwash during storms. The exception is anisolated overwash fan in the vicinity of Salterpath. Charr courtesy of N.C. Seagrant College !!ei&sletter, June, 1977, (Voi. 4, No. 61, Raleigh, N.C.
Source: Von Oesen and Freeman, 1975. growth and economy is the relatively large proportions of State and Federally owned land in the county. Federal land consists of 71,000 acres and state land consists of 27,300 acres for a total of about 29 percent of the total county land. Croatan National Forest accounts for much of this area. (Von Oesen, 1970, 1977).
Groundwater
Groundwater is the only community water source in the complex. It is obtained from three geologic strata of various ages; the oldest age penetrated by a well in Onslow County is the Pee Dee formation, which lies within 30 feet of the surface in some valleys of the county, Coastward, the Pee Dee is more deeply buried, lying under a wedge of Castle Hayne limestone which thickens toward the coast. The Yorktown formation overlies the Castle Hayne. The Yorktown and underlying Castle Hayne formations are considered together as the tertiary limestone or "rock" aquifer. The two main aquifers of the complex are the upper unconfined aquifer, or the surficial sands, and the tertiary limestone unit. Both sources are usable on the mainland; however, on parts of Bogue Banks the surficial sands may be the only viable aquifer due to salt water intrusion into the limestone. Recharge of the surficial aquifer is by rainfall.
The surficial sand yields water freely to well points, supplying water for most domestic uses. The groundwater table is generally at or within 6 feet of the surface in the Swansboro area, and within 10 feet of the surface in the remainder of the complex. The surficial aquifer is about 30 feet thick in the area near Swansboro and is expected to yield only small amounts of of water to wells. However, in the eastern part of the complex, the deposits are over 400 feet thick and are capable of fresh water yields of as much as several hundred gallons per minute, provided the deposits do not contain salt water. The surficial sand yields water that is soft and low in dissolved mineral matter. The water generally contains enough dissolved carbon dioxide to render it corrosive.
The upper sandy aquifer is underlain by the limestone aquifer. The limestone aquifer is about 600 feet thick in the western part of the complex and thickens to about 1,400 feet at the eastern end of the mainland. Potential well yields may be estimated using three factors; the increasing depth to the top of the aquifer eastward, the thickening to the east, and the decreasing depth of the fresh water zone to the east and toward the coast. When all of these factors are considered, potential yields to individual wells are estimated to be as great as several thousand gallons per minute in the western and central parts of the county's mainland and diminishing to a few hundred gallons per minute along the eastern margin of the mainland. Practical well yields of up to a few hundred gallons per minute can be obtained on the offshore islands on the south side of the county. Fresh water might be produced from the limestone aquifer on the offshore islands on the east side of the c~ounty. Although the Yorktown formation locally contains some clay in its upper sections, and although both formations contain some unconsolidated quartz sand and calcareous sand beds, almost all wells entering these formations draw water from the rock. In order to guard against salt water intrusion, the wells are pumped so that the pumping level does not fall below 20 feet below sea level. Water from this limestone aquifer is hard, the chief dissolved mineral constituents being calcium and bicarbonate. In places the water in the limestone contains objectionable amounts of iron. For this reason, some treatment of large water supplies is required in most cases. (Von Oesen, 1975, 1977.)
Water Supply
The towns of Beaufort, Newport, Morehead City and Swansboro now own and operate their own municipal water systems. Atlantic Beach is constructing a municipal system that is designed to serve the present town and areas of East Bogue Banks to the east and west that it expects to annex in future years. Private water companies serve Emerald Isle, Indian Beach (Salterpath) and Pine Knoll Shores. There are no community water systems in Cape Carteret and Indian Beach. Groundwater resources are more than adequate to serve the area in the indefinite future.
Wastewater Treatment
There are four existing municipal wastewater collection, treatment, and disposal systems located in the complex. These are all on the mainland, in the towns of Beaufort, Morehead City, Newport and Swansboro (See Map 3-1). The wastewater collection system in Beaufort is In two parts; the original system (a combined sanitary and storm sewer system serving the downtown area) and the extended system (a recently installed sanitary sewer system serving the remainder of the population within the town limits). The total system is comprised of 16.7 miles of primarily vitrified clay pipe (sized from 6-in. to 16-in. diameter), with some recent extentions of PVC pipe. The original system was installed during the 1920's and the outfalls were directed to Taylor's Creek. In 1969, the sewers diverted their flows to Beaufort's new 0.75-MGD treatment facility. One combined outfall into Taylor's Creek still exists.
The town uses a completely mixed activated sludge system to treat its wastewaters before discharge into Taylor's Creek. Less than 10 percent of the wastewater flow is estimated to be industrial wastewater. Infiltration and storm water inflow are major problems because of the combined system in downtown Beaufort. Infrequent and irregular industrial wastewater discharges from a fish processing plant cause plant upsets.
The wastewater collect~onsystem of Morehead City is a sanitary sewer system connected to the existing treatment facility in 1964. The system consists of approximately 26 miles of 6 to 24-in, diameter lines. For the most part, the collection system consists of virtified clay pipe. The trickling filter wastewater treatment facility has a design capacity of 1.7 MGD and discharges into Calico Creek. Approximately 10 percent of the flow reaching the plant is industrial wastewater, Storm water inflow into the collection system constitutes a major problem.
The collection system and wastewater treatment facility for Newport was constructed in 1965. The collection system consists of approximately 7.6 miles of 6 to 12-inch diameter virtified clay lines. The contact stabilization activated sludge wastewater treatment facility operated by Newport has a design capacity of 0.25 MGD and discharges into the Newport River. No industries of any significance discharge wastewater into the municipal system. Due to the relative newness of the collection system; no infiltration or storm inflow problems exist.
The wastewater collection system of Swansboro was constructed between 1953 and 1960, utilizing vitrified clay pipes with oakum and mortar joints. The system includes approximately 29,700 feet of 8, 10, and 12-inch diameter vitrified clay pipe. The wastewater treatment facility consists of a structure for flow measurement and bar screens, an Zmhoff tank, and a sludge drying bed. The design capacity is 0.25 MGD. The effluent is not chlorinated before discharge into the White Oak River. There is a small amount of industrial flow in the system. Storm water inflow and infiltration are not major problems. A moratorium on sewer expansion, due to the inadequacy of the wastewater treatment facility prevents more connections to the system. The existing facility cannot treat wastewater to an acceptable quality for discharge into the White Oak River.
Many package plants and aerated lagoons throughout the area serve mobile home parks, restaurants, hotels and motels. These facilities discharge their effluents either to the inland waters or to subsurface disposal. Package plants typically consist of an activated sludge unit followed by tertiary filtration and chlorination. Aerated or oxidation lagoons are basically detention tanks where sedimentation, sludge stabilization, biological treatment and bacterial dieoff take place. These facilities if operated properly, can achieve a good quality effluent. However, operation is generally poor, and in any event each discharge represents a point source of pollution to fragile inland waters and their monitoring is difficult.
The predominant form of wastewater handling by is septic tank systems, including the fields, which are notorious for their high rate of failure, particularly in densely populated areas where the soil is poor and the water table is high. The density of this area is expected to increase, thus septic tank systems cannot be the long term solution for wastewater handling. (Von Oesen, 1975, 1977.) Existing Quality in Area Surface Waters
Certain zones within the complex have been degraded by pollutants to the extent that the harvesting of shellfish for marketing has been prohibited by the Office of the North Carolina Shellfish Sanitation Program, Division of Health Services, based in Morehead City. The closings result from total coliform levels in excess of the 70/100 ml standard. The source of the contamination is presumed to be seepage from failed or malfunctioning septic tanks, from domestic wastewater point sources, from urban runoff and a combination of these.
The waters in the White Oak River north of Swansboro, where the unchlorinated primary effluent from the existing Swansboro wastewater treatment facility is discharged, are used extensively for recreational purposes (mainly fishing and boating). It is the expressed desire of the local community to remove the potential hazards to humans associated with this discharge and to improve the water quality of that segment of the White Oak River. Similar desires have been voiced in regard to the Newport and North Rivers. The points of discharge for the wastewater treatment facilities of the complex are into estuarine waters. Thus the wastewater is not assured of being swept out to sea, but may move upstream or downstream, or remain immobile, based on the influence of the tides, winds and upstream conditions.
The North Carolina Coastal Resources Commission recently issued guidelines for planning in the coastal zone in accord with the provisions of G.S. 113A-107(e) of the Coastal Management Act of 1974. The guidelines take cognizance of the fact that the estuaries of the state are among the most productive of its natural environments, which support valuable commercial and sport fisheries and are used for commercial navigation, recreation and amenity. The guidelines note that the high value of the estuaries is dependent upon the protection and sustained quality of the estuarine waters.
A policy objective of the guidelines is to preserve and manage estuarine waters so as to safeguard and perpetuate their biological, economic and esthetic values. The highest priority is allocated to the conservation of estuarine waters. Projects which would directly or indirectly "cause adverse water circulation patterns, violate water quality standards, or cause degradation of shellfish waters are generally considered incompatible with the management of estuarine waters.
The guidelines also take cognizance of the naturally occurring aquifers on the Outer Banks and Barrier Islands such as Bogue Banks, and of their sensitivity to contamination from wastewater residuals. It is noted that very little filtration of chemical contaminants or of viruses is afforded by the sandy soils, and the potential exists for extensive pollution of these supplies, rendering them unsafe as sources of public water supply.
Another policy objective fostered by the guidelines is to eliminate as nearly as possible the potentfa1 for contamination of surficial aquifer areas that may result in public health hazards. (Von Oesen, 1977.) The waters of the complex are slowly being degraded, as witnessed by the downward reclassification of waters formerly suitable for shellfish harvesting to being unsuitable for bathing. This deterioration is proceeding by a slow piecemeal process with small areas of water being condemned after each shellfish sanitation study, The poor soils and high densities of housing combine to make sewage disposal by septic tanks virtually impossible. Furthermore septic tank and package plant systems that discharge effluents into the surficial aquifer foul the water sources for many domestic users. The density of the complex has reached a point where sound management of wastewater collection and disposal is imperative.
Water Demands and Wastewater Flows
Population estimates are shown in Chapter I. The mainland communities are not affected by the seasonal tourism that causes the Bogue Banks population to vary. Water demands are estimated by assuming 100 to 120 gpcd water usage, depending upon the community: Morehead City, 120; Morehead City/Newport township, 115 gpcd; and the remaining communittes, 100 gpcd. The domestic wastewater flows are assumed to be 80 percent of the water use, although 85 percent is used on West Bogue Banks to account for the wastewater flow of day visitors, who are not included in the population figure. To this figure is added industrial flow and infiltration/storm inflow in existing collection systems. The infiltration/storm inflow figure is taken from the results of the Carteret County and Swansboro 201 Pacililities Plans as presented by Henry Von Oesen and Associates, In Morehead City, a program to reduce infiltration/storm inflows by 50 percent is reported as cost effective. In Beaufort, a combined system in the downtown section makes reduction of the extraneous flows difficult, and an aerated storage or equalizing basin before the treatment facility is deemed the most effective method of controlling the stormwater surges. While this does not alleviate storm inflow, it does control the surges through the treatment facility and allows storage of wastewater until it provided for central collection of wastewater from many surrounding areas flow. In Newport, the infiltration/storm inflow figure is neglected as it is small and the collection systems is relatively new. (See Tables 3-2, 3-3.) Excess Capacity. The existing wastewater treatment facili.ties of Morehead City and Beaufort have capacities which allow them to continue treating wastewater for a number sf years before requiring expansion. The Morehead City treatment facility, when treating the wastewaters from within its town limits and from a sectdon of Morehead City/Newport township, has no need of expansion until the year 1991. The Reaufort treatment facility when treating the wastewaters from within its town limits, has no need for expansion until the year 1984.
The Swansboro area 201 facility plan concludes that the existing facility at Swansboro, due to a confined site and the outdated nature of the system (Imhoff tank), should be abandoned in fav~rof the construction of a new facility at a different location. D~SDOS~Options
The options evaluated for the Carteret County-Swansboro area are discharge to inland waters, to the ocean and application to the land.
Table 3-2. Southern Area Water Demands
Water Demands for Summer Peak (MGD)
1980
Beauf ort East Bogue Banks Morehead City Newport Morehead City/Newport Twp. Swansboro Cape Carteret West Bogue Banks
TOTAL
Water Demands for Winter (MGD)
Beauf ort East Bogue Banks Morehead City Newpor t Morehead City/Newport Twp. Swansboro Cape Carteret West Bogue Banks
TOTAL Table 3-3. Southern Area Wastewater Flows
Wastewater Flows for Summer Peak (MGD)
Beauf ort East Bogue Banks Morehead City Newport Morehead City/Newport Twp Swansboro Cape Carteret West Bogue Banks
TOTAL
Wastewater Flows for Winter (MGD)
Beauf ort East Bogue Banks Morehead City Newpor t Morehead City/Newport Twp. Swansboro Cape Carteret West Bogue Banks
Inland Waters
Surface water bodies within the complex include Bogue Sound, North River, Newport River, White Oak River and Queens Creek. Rogue and Beaufort Inlets connect these waters to the ocean on the west and east ends of Bogue Banks respectively. Foster Creek, which currently receives the treated wastewater from Swansboro, is a tributary of the White Oak River. Calico Creek, which receives the treated wastewater of Morehead City is a tributary of the Newport River. Taylor Creek, which receives the treated wastewater of Beaufort, is a tributary of the North River and Beaufort Inlet. The existing municipal point source discharge of the Reaufort treatment facility is classified as effluent limited while those of the existing facilities at Morehead City, Newport and Swansboro are classified as water quality limited. Effluent limited waters require secondary treatment as a minimum, with additional treatment based on the "SC" or "SB" classification of the water. Water quality limited waters require advanced wastewater treatment. Bogue Sound and portions of the White Oak, Newport and North Rivers contain valuable shellfish beds and are classified "SAW (shellfish waters) to protect them. Many pockets of "SC" (swamp water) exist throughout these water bodies. The Atlantic Ocean off of the Bogue Banks is classified "SB" to protect waters designated for swimming or recreation. Map 3-2 identifies the present (1979) water quality classifications of the water bodies of the complex.
As stated earlier, regulation 2-79 prohibits wastewater discharges to waters classified "SAW, thus limiting discharges to "SB" or "SC" waters. In the interests of cleaning up the shellfishing waters tributary to the Newport River and Taylor Creek, Newport and Beaufort are being viewed as discontinuing their effluent discharges into these water bodies. Thus for this report, Newport and Beaufort must divert their wastewaters to other sites,
Bogue Sound is not to be considered for the disposal of wastewater effluents. Bogue Sound is a shallow body of water with no means of flushing itself except by tidal variations between the inlets at each end of the sound. Currents move slowly through the sound, with a maximum velocity of about 2 feet per second. An effluent discharged to this area would not have the mixing or dilution as in a stream or inlet, and would be detrimental to shellfish production.
Continued discharge to inland coastal waters may continue at two locations: 1) Calico Creek near Morehead City, and 2) the White Oak River near Swansboro. Limiting wastewater discharges to two sites will permit other previously-closed waters to be given the opportunity to cleanse themselves, and will permit better control of the buffer zone limits. (See Map 3-3.) Ocean Discharge
The site selected for the ocean outfall is In the Pine Knoll Shores Area, 8.4 miles west of Beaufort Inlet (Map 3-3). This location is selected because it provides for central collection of wastewater from many surrounding areas and because land is available. The slope of the ocean bottom proceeding seaward from this site is typical of the ariaa. A summary of ocean depths at various distances from shore obtained from nautical charts prepared by the National Oceanic and Atmospheric Administration is presented in Table 7-4. The bottom falls to about 48 feet below the ocean surface at a distance of 9,000 ft. from shore and then remains at a depth of about 50 feet for a considerable distance. This topography necessitates a more shallow discharge than is available in the Northern Area, but adequate dilution can be provided.
As for the Northern area four different wastewater treatment process alternatives were examined for use with ocean outfalls at this location. These were (1) primary treatment alone, (2) primary treatment and disinfection, (3) secondary treatment alone, and (4) secondary treatment with disinfection. The base design year was 1980. The design lives of the
wastewater treatment facilities and of the ocean outfall pipe and diffuser were assumed to be 20 years, so that the end of the design period occurs in the year 2000.
The average daily wastewater flow during the year 2000 was estimated to be 8.9 MGD (13.7 cfs) if the wastewaters of the entire study area are collected and discharged to the ocean at this site. Inland disposal of some wastewaters by land application would reduce this flow. An average flow of 6.9 MGD (10.7 cfs) was considered to be the lowest feasible ocean discharge.
This flow corresponds to the average daily flow in the year 2000 from Morehead City, West Bogue Banks, and East Bogue Banks.
Table 3-4. Ocean Depth as a Function of Distance From Shore for the Proposed Bogue Banks Outfall
Distance from Shore Ocean Depth (Feet) (Feet)
Ocean Water Characteristics. Baseline water quality data are not available for the discharge area. The ocean waters contain sufficient dissolved oxygen to prevent anoxic conditions in the water column at a well-designed diffuser providing an initial dilution of 60 to 1 or greater. Similarly, problems should not arise from discharge of biodegradable organic wastes at BOD concentrations discharged from the treatment facility, Toxic substances should be excluded from the sewerage system and prevented from entering the ocean in significant amounts. Nutrient additions to the ocean are also expected to be unimportant and, in fact, many be beneficial. The treatment outfall-diffuser systems were designed to provide concentrations of fecal coliforms at the Bogue Island beaches of 200 per 100 milliliters or less, the limit for Class SB waters,
In the absence of temperature, salinity, and current data, it is assumed consequently that the ocean waters are unstratified and that a critical onshore current velocity of 7 cm/s would be maintained throughout the duration of travel as wastewater constitutents are diluted, changed and carried to the shoreline. A further consideration for this location is the existence of ocean shellfish beds. Areas such as this exist off the coast of the study area for shrimp and scallops (see Map 3-4 and 3-5). However, these are not critical when considering domestic wastewater discharges as these shellfish, unlike clams and oysters, are not ingested raw.
Wastewater Treatment and Ocean Disposal Systems. Results of analyses of the performance of the four wastewater treatment and disposal systems considered for the Southern Area are presented in Table 3-5. All of these alternatives yield predicted concentrations of fecal colifoms at the beaches of less than 200 per 100 ml, the standard for Class SB waters. These designs are based on an average daily discharge in the year 2000 of 8.9 MGD, corresponding to the collection, treatment and discharge of all wastewaters in the study area. Alternative A, primary treatment alone, requires the longest outfall (3.3 miles), while alternative D, secondary treatment with chlorination, uses the shortest outfall (1.3 miles).
Alternatives B and C have different treatment schemes (primary treatment with chlorination versus secondary treatment alone) but use identical outfall lengths. This is because the coliform concentrations in the effluents from these treatment systems are estimated to be equal, at 8 x 106 per 100 ml.
The outfall pipe for each alternative has a diameter of 27 inches and terminates in a diffuser comprised of 24 ports located at 20-foot spacings. The procedures used in obtaining these designs are similar to those described in the Appendix (Spiegel, 1978) and used for the Dare County area.
Several different wastewater management plans are examined for this area. In many of these, various portions of the total flow are collected and discharged at different sites by different methods. The range of discharges at the ocean outfall site is from 6.9 to 8.9 MGD. In considering the design of the ocean outfall pipe and diffuser for each of these water flows, the outfall lengths presented in Table 3-5 for each treatment process alternative were assumed, and the diameter of the outfall pipe and diffuser was reduced in appropriate proportion to the flow. For example, a pipe diameter of 24 inches in required for a wastewater flow of 6.9 MGD. Costs of each outfall system are determined on the basis of the appropriate pipe diameter.
Costs of the four treatment and disposal alternatives for the complete regional system (flow = 8.9 MGD) are presented in Table 3-6. Ranked in order of increasing costs, the results are (1) primary treatment with chlorination, (2) primary treatment alone, (3) secondary treatment with chlorination, and (4) secondary treatment alone. The costs include the capital costs of all treatment components and the outfall system, and the present value of the operation and maintenance costs of the treatment and outfall system.
Beaufort. Effluent from the existing treatment Eacility at Beaufort may be applied to a site near the facility. Wastewater characteristics are ISH'ING GROUXUS, ONSL-OW BAY, M. C.
CALICO SCALLOPS MAP: 3-5 COMMERCIAL FISHING GRQUNDS, C'idStOW BAY, N. C.
SHRIMP
BASED ON: A i lxEW OF THE ---OCEANOGR9f-I 'i- AND ---FISHERY OF --ONSLOW BAY, _!(&i'l't-I CAROL1 NA (1374) 3 0 &-L,.s'O%.-ST ,>-FA 90 SCALE OF MILES Table 3-5. Treatment and Ocean Disposal Alternatives
Effluent Coliform Reductions by Dilution Coliform Outfall Discharge and Dieoff in the OceanX Predicted Treatment Conc. Length ~e~th- Initial Lateral Beach Area Alternative (per 100 ml) (Miles) (Ft-) Dilution Dispersion ~ieoff** Conc. (per 100ml)
A Primary 8 X 107 3.3 50 7 0 28 219 Treatment
B Primary Treatment Plus Disinfection 8 X lo6 2.2 w L I KI Secondary P Trea trnent 8 X lo6 2.2
D Secondary Treatment Plus Disinfection 8 X 105 1.3 4 8
* Reduction factor: coliform conc, before dilution or dieoff/coliform conc. after dilution or dieoff.
**Dieoff based on tgo = 9 Hours. Table 3-6. Costs of Treatment And Ocean Disposal Alternatives for the Carteret-Onslow County Area*
Outfall Capital Present Value Treatment Length Costs 09M Costs Total Costs Alternative (Miles) ($ Millions) ($ Millions) ($ Millions)
A Primary Treatment 3.3 8.1 1.9 10.0
B Primary Treatment Plus Chlorination 2.2 6.8 2.4
C Secondary Treatment
D Secondary Treatment Plus Chlorination 1.3 8.3
*~esipFlow = 8.88 MGD estimated in in Table 3-7. Flow is expected to increase about 33% during the design period and the difference between summer and winter flow will increase slightly.
There are several soils near the treatment facility: State loamy sand (f ine-loamy, mixed, thermic, Typic Hapludult) ; Altavista fine sandy loam (fine loamy, mixed, thermic Aquic Hapludult); and Augusta fine sandy loam (fine-loamy, mixed, thermic, Aeric Ochraquult).
State is a well drained soil but the Altavista and Augusta will require artificial drainage to be suitable for land application. Additional data on these soils is contained in the Appendix.
The proposed site is located just north of the treatment facility (Figure 3-2). The site contains 150 acres of which 100 acres are suitable for irrigation. Drainage will be required on 80 acres.
On the basis of 2000 flow, the loading rates are: Nitrogen: 510 lb/acre/yr Phosphorus: 204 ~b/acre/~r* Hydraulic: 2.4 inc./week (summer flow)
Morehead City, Newport and Morehead City/Newport Township
Characteristics of wastewater from each area and characteristics of the combined flow are shown in Table 3-8. It is assumed that the differences between winter and summer flows are ngeligible. Much of the flow in the Morehead City system is a result of groundwater infiltration into the sewer system.
Soils suitable for land application in the Morehead City area include: Norfolk loamy fine sand (fine-loamy, siliceous, thermic, Typic Paleudults); Lynchburg fine sandy loam (fine-loamy, siliceous, thermic, Aeric Paleaquults); Goldsboro fine sandy loam (fine-loamy, siliceous, thermic, Aquic Paleudults); and Kenansville loamy sand (loamy, siliceous thermic Arenic Hapludults).
Norfolk and Kenansville soils are well drained but Goldsboro and Lynchburg require artificial drainage to be suitable for land application. Additional data on these soils is contained in the Appendix.
The proposed site is located in the Wildwood area along both sides of SR1152 between the railroad and the Newport River (Figure 3-3). The site contains 430 acres of which 236 are suitable for irrigation and 33 are suitable for lagoon for treatment and storage. Drainage will be required on 155 acres.
*All soils proposed to receive wastewater in Carteret County have sufficient clay content that P fixation should retain the P not taken up by crops. Table 3-7. Wastewater Characteristics for ~eaufortl -
Weighted Parameter summe r-2 Winter Me an
~low3/,- mgd
p4/- load, lb/yr
- TOD loads are so low as to be insignificant in determining the irrigation rate. Consequently they have been omitted in characterization of waste- water in the southern area. -21 Summer: May 15-September 15 -31 Flow includes 0.21 mgd infiltration flow -4/ N and P loads are based on total flow minus infiltration flow, N = 25 mg/l P = 10 mg/l.
Source: King, 1978. FIGURE 3-2. Land Application Site and Soils for Beaufort
3-25 On the basis of 2000 flow, the loading rates are Nitrogen: 593 lb/acre/yr Phosphorous: 237 lb/acre/yr Hydraulic: 2.6 in. /wk .
Table 3-8. Wastewater Characteristics for Morehead City, Newport and Morehead/Newport Township.
Morehead Morehead/ City Newport Newport TWP Total
FLOW, mgd
~21- load, lb/yr
~2/- load, lb/yr
-11 Flow includes 0.6 mgd infiltration flow -21 N and P loads are based on total flow minus infiltration flow, N = 25 ppm, P = 10 ppm
Source: King, 1978. FIGURE 3-3. Land Application Site and Soils for Morehead City, Newport, and the Morehead CitylNewport Township
3-27 Morehead City. In the option in which flows from Newport and Morehead city are handled separately, it is assumed that 213 of the flow from the township would be treated at the existing Morehead City facility. Flows for the years 1990 and 2000 are 1.65 and 2.01 MGD respectively.
The soils are the same at those used for the combined flows.
The proposed site is a 330-acre section of the site proposed for the combined flows. The site contains 200 acres of irrigable land. Drainage is required on 120 acres and clearing on 65 acres. Based on the 2000 flow, application rates are:
Nitrogen: 534 lb N/acre year Phosphorous: 214 lb P/acre/yr Hydraulic: 2.6 in. /wk
Newport. In the option in which wastewaters from Newport and Morehead City are handled separately, it is assumed that 1/3 of the flow from the township would be treated at the existing Newport treatment facility. Flows for the years 1990 and 2000 are 0.35 and 0.43 MGD, respectively.
Soils available in the Newport area are Kenansville loamy sand and Lynchburg fine sandy loam.
The proposed site is located northeast of the junction of US 70 and SR1247 between the railroad and the Newport River (Figure 3-4). The site contains 90 acres of which 55 are irrigated. Fifteen acres require drainage.
On the basis of the 2000 flow, application rates are: Nitrogen: 595 lb N/acre/yr Phosphorus: 238 lb/P/acre/ yr Hydraulic: 2 in. /wk
East and West Bogue Banks, Cape Carteret, and Swansboro
Wastewater flow and wastewater characteristics for the individual areas and the combined areas are shown in Table 3-9. Total flow is expected to roughly double during the design period. Winter flow will average 27% of summer flow.
Suitable soils in the western part of the county include Raymeade, Kenansville, Goldsboro, Lynchburg, Chipley, Northfolk and Kureb.
The proposed site is generally bounded by Pettiford Creek, White Oak River, NC 58, SR1109 and SR1106. Starkey Creek bisects the site. The site contains 768 acres of which 450 acres are irrigable. As shown by the cross hatched areas in Figure 3-5 much of the site consists of irregular areas of soils unsuitable for effluent application. An additional 65 acres will be required for treatment and 30 days of storage at the 2000 summer flow rate. Drainage will be required on 110 acres of the irrigable land, At the 2000 flow rate, loading rates are: FIGURE 3-4. Land Application Site and Soils for hewport
3-29 Table 3-9. Wastewater Characteristics for East Bogue Bank, West Bogue Bank, Cape Carteret and Swansboro.
East Bogue Bank West Bogue Bank Total Weighted Weighted Cape Weighted Summer Winter Mean Summer Winter Mean Carteret Swansboro Summer Winter Mean
Flow, mgd 1980 1.5 1990 2.6 2000 3.4
N load 1b/jm2/- 1980 38,500 1990 66,700 W 2000 87,200 I W 0 P load ~b/~r~/- 1980 15,400 1990 26,700 2000 34,900
-11 Includes 0.06 mgd infiltration flow.
-2/ Based on total flow minus infiltration flow. N=25 ppm, P=10 ppm.
Source: King, 1978. FIGURE 3-5. Land Application Site and Soils for East and West Bogue Banks, Cape Carteret, and Swansboro
3-3 1 Nitrogen: 458 lb/acre/yr Fhosphorus: 183 lbjacrelyr Hydraulic: 3.1 in./week at sunmer flow rate
East and West Bogue Banks and Cape Carteret
If Swansboro is not included in the land application system for western Carteret County, the mean flow would be reduced by about 5%. It is assumed that the system would be scaled down by 5% with a resulting reduction in cost of 5%.
Cape Carteret, Swansboro and Cape Carteret + Swansboro If the effluent from East and West Bogue Banks is not applied to land, effluent from Cape Carteret and Swansboro or from Cape Carteret only would be applied to a smaller area of the site proposed for the western part of the county. If effluent from Swansboro is not applied to this site, then it could be applied to a site near Swansboro. An actual site near Swansboro was not chosen because there are no detailed soil maps of the area. However, an on-site inspection of the area north of Swansboro indicated that there is an adequate amount (60 acres) of well drained soil within two miles of Swansboro.
Wastewater Collection
Sixty regional plans were selected for study from a much greater number of possible arrangements. These plans are formed from combinations of 33 local sewerage alternatives, each of which serves one to seven towns. The plans are presented schematically in Figure 3-6, while details are contained in the Appendix. The sewerage alternatives are an attempt to link possible disposal sites and towns in various arrangements, to find an optimal system.
Wastewater Treatment Facilities
The location of wastewater treatment facilities is an important aspect of the sewerage system. The existing facilities at Morehead City, Newport and Beaufort can be enlarged, and these sites are included in the proposed plans. Some plans may call for closing an existing facility, with the present flow being transported to a new treatment facility. The existing facility at Swansboro is located at a site which does not have room for expansion. Thus expansion of this facility is not considered and a new site is chosen. This results from the Swansboro 201 study by Henry Von Oesen and Associated (1977).
Where land application is considered as the disposal mode, such as near Cape Carteret, a facility is planned to be on the land application site. For the land application site near Morehead City and Newport, three different alternatives for treatment are considered. These are 1) continued separate treatment at the Morehead City and Newport facilities, 2) closing Newport's facility and treating the total flow at Morehead City, and 3) closing both treatment facilities and constructing a new facility at the land application Figure 3-6. Schematics for Treatment and Disposal A1 ternati ves
PLAN 1 PLAN 2 ON
CC MHC
WBB EBB WBB EBB
PLAN 3 PLAN 4 N
WBB EBB WBB EBB
KEY: EFFLUENT DISPOSAL
SW - Swansboro Treatment Facility CC - Cape Carteret WBB - West Bogue Banks Coastal Waters EBB - East Bogue Banks Land Application FlHC - Florehead City r4 - Newport Ocean Discharge B - Beaufort 0 - Comuni ty PLAN 5 PLAN 6 N
I MHC B
EBB WBB EBB WBB
PLAN 7 PLAN 8
EBB WBB EBB W BB
PLAN 10 N PLAN 9 PN
O----o EBB WBB EBB WBB PLAN 13
WBB EBB WBB EBB
PLAN 15
WBB EBB WBB EBB PLAN 17 PLAN 18
WBB EBB
PLAN 19
PLAN 21
WBB EBB dBB EBB PLAN 23 PN PLAN 24 N
MHC MHC S W B B
WBB EBB WBB EBB
PLAN 27
WBB EBB WBB EBB PLAN 29 PLAN 30
MHC
WBB EBB WBB EBB
PLAN 32 PLAN 31 N
WBB EBB WBB EBB
PLAN 34 N PLAN 33 N
WBB EBB PLAN 35 N PLAN 36 N
C C MHC CC MHC
WBB EBB WBB EBB
PLAN 37 N PLAN 38 N
CC MHC
WBB EBB WBB EBB
PLAN 39 14 PLAN 40 N
CC MHC SW
WBB EBB WBB EBB PLAN 41
PLAN 43
WBB EBB
PLAN 45 PLAN 47 N PLAN 48 N
MHC
WBB EBB
PLAN 49 N
6 cc MHc
WBB EBB
PLAN PLAN 52 N
MHC SW B
WBB EBB
site. The Beaufort wastewater treatment facility is near the land application site and no other location is considered. A new facility for Swansboro is considered at its land application site.
The remaining treatment facility site is on the Rogue Ranks, for ocean discharge. This facility is located at Pine Knoll Shores, roughly on the line which separates the Swansboro 201 area from the Carteret County 201 area. This site is selected because of its central location and because of the primary dune system which may help protect the structure from the sea. (See map 3-6 for locations of treatment Eacilities.)
Sewerage System Plans
As there are seven towns and three or four disposal sites for each, the number of combinations for treatment and disposal is large. For instance, West Bogue Banks may dispose of its effluent to a land site near Cape Carteret, to the White Oak River, to Calico Creek or to the ocean. To treat its wastewater, it may combine with any of the other 6 towns. In order to decrease the total number of possibilities, the following assumptions are made :
1) The ocean outfall needs to serve at least the Rogue Banks and Morehead City to be economically justifiable. 2) 'Re wastewater flows Erom East and West Bogue Ranks are treated in their entirety. Conducting part of the flow in one direction and part in another is not considered. 3) The land application site near Cape Carteret is adequate for only Swansboro, Cape Carteret, and East and West Rogue Ranks, or any lesser combination of these. 4) The land application site located between Morehead City and Newport is adequate for the wastewater from Newport, Morehend City and Morehead City/Newport township. If only Newport and a section of Morehead City/Newport township is to use the land application site, a smaller site is available near the town of Newport. 5) The land application site located near Beaufort can only handle wastewater from Beaufort. 6) The land application site near Swansboro can only handle wastewater from Swansboro.
Design Assumptions. Several design assumptions were made: I) Bogue Ranks and the areas around Reaufort, Morehead City, Cape Carteret and Swansboro have no significant variation in elevation, and are treated as if they are flat. 2) The populations of East and West Bogue Ranks are distributed over the area in such a manner that the tributary load to the intercepting sewer is unifirom. This tributary load is different for the East and West ends of the island, and the line dividing the Carteret County 201 study area Erom the Swansboro 201 study area is used to distinguish the two parts of the island. 3) The Bogue Banks are serviced by an intercepting sewer that extends from Fort Macon on the East to the Emerald Isle-Cape Carteret Bridge on the west. 4) The wastewater flows from the towns of Newport, Beaufort, and Swansboro are considered as point sources from each of these locations. 5) Cape Carteret is considered as a point source. However, the commercial district of Cape Carteret which extends to Cedar point is serviced by an intercepting sewer. 6) Morehead City is considered as a point source. However, an addition to the existing sewer system is included to service the area from Route NC24 to the town limits. This addition will provide service to part of the area designated as the Morehead City/Newport township. 7) The Cape Carteret-Emerald Isle Bridge is continuous and can support a force main. 8) The Morehead City-Beaufort Bridge is continuous and can support a force main. It reaches a helght of 200 feet. 9) The Morehead City-Atlantic Reach Bridge is a swing bridge which requires a subaqueous pipe section. The remainder of the bridge can support a force main. 10) Newport must pump its raw or treated effluent uphill to either the land application site, or to Morehead City. The magnitude of this rise is 35 feet.
The assumption of flat terrain on the coast is justified as the elevations are near sea level in the marsh lands. However a rise of about 35 feet between Newport and Morehead City would require a pump station and force main.
Rogue Banks is a long and narrow, flat stretch of island which is basically inhabited in three nodes, but is currently undergoing strip development. The three modes exist at Emerald Isle, Indian BeachISalterpath, and Atlantic Reach. Strip development, or development along a main highway, is common in coastal regions, and as no preuse prediction can be made, as to where the population will he settled in the next twenty years, a uniform tributary load is assumed. Although a boundaryline such as "201" study area differentiation line is arbitrary, it is used to show the difference in population density between the East and West portions of the island.
The uniform tributary load on the Bogue Banks is modeled as occurring between Fort Macon on the east and the Emerald Isle-Carteret bridge on the West. This does not mean that no wastewater is generated from Fort Macon or below the bridge, but as an approximation for the sewerage system, this area is large enough. The flow generated at Fort Macon is considered in the population estimate as day visitors, and the Fort will he permitted to discharge into the interceptor sewer, but must deliver its flow to the sewer which begins immediately outside the Fort.
The tawn of Newport is considered as a point source. This means that all wastewater flow in the town of Newport will arrive at the wastewater treatment facility wet well and from there will either be treated or pumped to another treatment facility. In order to divert its Elow to Morehead City, Newport must pqp uphill. As the existing treatment faciity is located near the Newport River, a low point, it can be assumed that new additions to the sewer system will continue to flow to this low point. Even if a series of lift stations is needed to connect Newport and its outlying areas, this cost would be equal in all plans, and is not necessary for comparison of options.
The town of Beaufort is also considered as a point source. As Beaufort is isolated from the other towns and must be connected with them by pumping across the Morehead City-Beaufort Bridge, no interceptor sewer plan can be applied. As the area between the wastewater treatment facility and the bridge is provided sewer service, additional sewer service would come from outlying areas to the existing treatment facility and thus be an equal cost in every plan. The existing treatment facility wet well now receives all the wastewater of the town, and it is assumed that all new flow will continue to flow to this location.
The town of Cape Carteret is considered a point source except for the Cedar Point region. No sewerage system presently exists in Cape Carteret. The preliminary collection system design (Von Oesen, 1977) relies on a pump station located in the center of this area. As the area is flat, the pump station-force main is an important feature of this system. Although this report proposes a lagoon at another location in Cape Carteret, the cost of the collection system is equal in all plans, and is not necessary for comparison.
The Cedar Point section of Cape Carteret is a commercial area which is considered to have a uniform tributary flow as it is strip development along highway NC 24. An interceptor sewer is utilized for this area.
The town of Swansboro is considered as a point source. The existing treatment facility currently receives the wastewater of Swansboro, and any newly annexed areas can direct their wastewaters to this wet well or to the site of a new facility. It is assumed that the current facility is to be closed. However a pumping station can still be operated at the site. All flow is considered to travel to the existing wastewater treatment facility, and from there may be transported to the land application sites at Swansboro or Cape Carteret, or to a new wastewater treatment facility site.
Morehead City is considered as a point source, but an addition to the existing sewer system in the form of an interceptor sewer is included. This addition is to service part of an area designated the Morehead City/Newport township. All wastewater presently flows to the existing wastewater treatment facility. The additional sewerage system will extend to the wastewater treatment facility from Route NC 24, where new development is planned. This flow will be diverted from the Morehead City treatment facility to another location. If the flow is to the land application site between Morehead City and Newport, the interceptor sewer will be directed to a pump station located at Route 24, and will carry the flow from Morehead City. Thus the flow from Morehead City is considered as a point source at the existing treatment facility's wet well. The water table is about 10 feet below the ground surface during most of the year, and may rise to within 6 feet of the ground surface in the spring. This means that part of the interceptor sewer line is under water all of the year. To prevent high infiltration, the joints must be secure and water tight, and the pipe and joint materials and methods of construction must be carefully selected.
The bridges are assumed to be structurally sound and able to support a pipe hung from them. The pipe material for bridge and subaqueous sections are reflected in the cost functions used.
Peaking factors used for preliminary design and cost estimates are shown in Table 3-10.
Table 3-10. Peaking Factors for Interceptor Sewers
1) Swansboro 3.0
2) Cape Carteret 3.0
3) Newport 3.0
4) Morehead City/Newport Township 3.0
5) Morehead City 2.5
6) West Bogue Banks 2.5
7) Beaufort 2.5
8) Swansboro + Cape Carteret 2.5 9) Newport + Morehead City/Newport Township 2.5
10) Parts of Atlantic Beach 2.5
11) Atlantic Beach 2.0
12) Newport + Morehead City + Beaufort 2.0
Any other combination of towns assumes the lowest peaking factor of the group. Costs of Sewerage Options
A summary of the results is shown in Table 3-11. Details of each sewerage system plan are shown in the Appendix. The costs of the sewerage system range from $23 to $34 million.
The lowest cost for sewerage are incurred when the individual towns serve only themselves, requiring the shortest lengths and smallest diameter sewers. This is shown by Plans 38 and 41 in which Newport, Beaufort, Cape Carteret and Swansboro have individual systems and Morehead City and the Bogue Banks are combined in a system discharging to the inland coastal waters. When discharging to the ocean, Cape Carteret and Swansboro may join the Bogue Banks-Morebead City system, as the centralized location of the Bogue Banks wastewater treatment facility allows the smallest diameter pipes to be used. This is shown in Plan 47, with Newport and Beaufort still being served by their own systems. Because of the distances between the centers of population in the service area, the largest sewerage costs are incurred where attempts are made to bring all the communities together. The higher sewerage costs are offset by economies in treatment and disposal, as shown later in the report.
Wastewater Treatment
Treatment systems are considered individually for each disposal option as each disposal mode has specific requirements. The disposal sites considered are the inland coastal sounds, Calico Creek, the White Oak River, five land applications sites and the ocean.
Inland Waters
Discharge into the inland coastal sounds is limited to waters having an "SC", swamp water, classification. As discussed above, the sites chosen for wastewater discharges are Calico Creek and the White Oak River. The wastewater treatment requirements are shown in Table 3-12. These waters are water quality limited, thus requiring advanced wastewater treatment. Nitrification is required for flows in excess of 0.3 mgd. Suspended solids concentrations are limited as the waters are tributary to shellfishing waters. When discharging to the White Oak River, conventional activated sludge treatment is projected, followed by a filter to achieve the suspended solids limit, and chlorination. The Eacility discharging to Calico Creek currently uses a trickling filter, and any expansion of the facility is based on trickling filters, followed by filtration and chlorination. Nitrification is used at each facility to meet the ammonia nitrogen limit, where applicable. An inplant pumping facility is included before the filtration unit, Sludge is handled by anaerobic digestion followed by drying beds, with the dried sludge being hauled to landfill. Table 3-11. Southern Area Interceptor Sewer Costs
Effluent Capital Cost P.V. O+M Cost Total Cost Plan ~is~osal* ($ Millions) ($ Millions) ($ Millions)
1. CW, L 2. CW, L 3. CW, L 4. CW, L 5. CW, L
CW, L CW, L C W L CW, L L CW, L CW, L CW, L CW, L
CW, L CW, L CW, L CW, L CW
L CW, L L CW, L CW, L
CW, L CW, L CW, L CW, L CW, L
*CW = Coastal Waters 0 = Ocean L = Land Table 3-11, Interceptor Sewer Costs (continued)
Effluent Capital Cost P.V. O+M Cost Total Cost Plan Disposal ($ Millions) ($ Millions) ($ Millions)
CW, L CW, L L E CW, L
CW, L CW, L CW, L CW, L CW, L
CW, L CW, L CW, L CW, L 0
L, 0 L, 0 L, 0 L, 0 L, 0
L, 0 L, 0 L, 0 L, 0 L, 0
L, 0 L, 0 L, 0 L, 0 L, 0 ------"CW = Coastal Waters 0 = Ocean L = Land Ocean Discharge
The waters of the Atlantic Ocean off of the Outer Banks are classified as "SB" for bathing and recreation, which fixes coliform bacteria limits for the beaches. Four treatment types are studied, primary and secondary treatment (activated sludge) with and without chlorination. Sludge is handled by anaerobic digestion followed by drying beds, with the dried sludge being hauled to a landfill.
Land Application
Prior to land application the wastewater received preliminary treatment, stabilization in an aerated lagoon, and chlorination. No sludge handling is necessary as the settled sludge is stabilized continuously in the lagoon.
When existing facilities are used prior to land application, secondary treatment is followed by chlorination. The Newport and Beaufort facilities both utilize activated sludge and Morehead City operates a trickling filter facility. Where this effluent is to be applied to land, the treatment available may be excessive. The costs reported in this section are for expansion of exlsting facilities which may represent some overdesign.
A 30-day storage lagoon for the flow of the year 2000 is located at all land application sites. These lagoons are to store treated effluent during wet periods or during extremely cold periods.
Costs for the Treatment O~tions
The costs for the treatment phase of the various options are shown in Table 3-13. ( A complete analysis of the options is contained in the appendix) . In general, treatment costs before discharge to the ocean or a land application site are lowest as no additional filtering or ammonia nitrogen removal is required after the basic treatment. Regionalized facilities, requiring the least number of treatment facilities produce the most cost effective options because of economies of scale. The treatment costs are, of course, only one part of the sewerage-treatment-disposal system costs.
Effluent D~SDOS~
This section considers the costs of the ocean outfalls, application systems for land disposal, and outfall lines into the coastal waters via Calico'Creek and the White Oak River. Results are shown in Table 3-14. Table 3-12. Wastewater Treatment Requirements
------Total Total Dissolved Suspended Coliform Flow BOD5 Ammonia Oxygen Solids Bacteria Location (MGD) (mg/l) (mdl) (mg/ 1) (mg/l> per 100 ml pH
Morehead City discharge to Calico Creek 2 5 15
Swansboro discharge to Foster's Creek No limit No limit 15
Swansboro discharge to Foster's Creek 10 No limit 15
W I Swansboro discharge to w Foster's Creek 5 No limit 15
Swansboro discharge to Foster's Creek 2 No limit 15
Swansboro discharge to Foster's Creek 2 No limit 15
Source: Peroutka ( 1978). Inland Waters
The discharge systems to Calico Creek and the White Oak River consist of a short outfall and a headwall. The cost of such systems is small and is neglected in this report.
Ocean Discharge
The length of an outfall varies with the degree of treatment achieved before discharge, and the flow. The lengths of the outfalls, including diffuser sections, as determined by the preliminary design are: 3.3 miles for primary treatment without chlorination: 2.2 miles for primary treatment with chlorination and secondary treatment without chlorination: and 1.3 miles for secondary treatment with chlorination.
A pump station is required and the pipeline must be able to resist salt water corrosion, as well as stay structurally sound under the influence of waves, tides and storms. Preliminary outfall designs are included elsewhere in this report, and only the cost estimates are presented here. These costs include the pumping station; a gravity sewer from the ocean to the pump station wet well which will allow flushing of the outfall during periods of low wastewater flow; a section of force main from the pump station to the subaqueous outfall line; and the outfall and diffuser itself.
Land Disposal
Land application is accomplished by sprinkler irrigation. Effluent is pumped from the treatment facility to each of the dipososal sites where it is applied to the fields. Sprinklers are of either the center pivot or solid set type, depending on the shape of the site. The effluent irrigation cost represents the costs for high lift pumping, forcemain, land, site preparation, the irrigation system, monitoring wells, fences, and are adjusted for the income to be derived from crop production.
Conclusions
This section includes assessment of the various plans. Cost minimization is not the sole criterion. The impact the effluents may have on the receiving waters and the economic integrity of the area must be considered. A table of the total cost of each option is presented in Table 3-15. (A more complete analysis of the cost is in the appendix).
For the 60 plans considered, the costs of the total systems range from $38 to $52 million. The least costly plans are 47, 48, 52, 55 and 59, which utilize ocean discharge of wastewater after primary treatment and chlorination, with one or more of the inland towns using land application. In each of these plans, Beaufort uses land application, and Morehead City and the Bogue Banks discharge to the ocean. Plans that are somewhat more costly include discharge to inland coastal waters for some of the communities. Table 3-13. Southern Area Treatment Costs
Effluent Capital Cost P.V. O+M Cost Total Cost Plan ~is~osal* ($- Millions) ($ ~illions) ($ Millions)
1. CW, L 2. CW, L 3. CW, L 4. CW, L 5. CW, L
6. CW, L 7. CW, L 8. CW 9. L 10. CW, L
11. L 12. CW, L 13. CW, L 14. CW, L 15. CW, L
16. CW, L 17. CW, L 18. CW, L 19. CW, L 20. C W
21. L 22. CW, L 2 3. L 2 4. CW, L 2 5. CW, L
26. CW, L 27. CW, L 28. CW, L 2 9. CW, L 30. CW, L
3 1. CW, L 3 2. CW, L 33. L 34. L 3 5. CW, L
* CW = Coastal Waters 0 = Ocean L = Land Table 3-13. Treatment Costs (continued)
Effluent Capital Cost P.V. O+M Cost Total Cost Plan Disposal ($ Millions) ($ Millions) ($ Millions)
CW, L cw, L CW, L cw, L
*CW = Coastal Waters 0 = Ocean L = Land
**For ocean disposal, primary treatment and chlorination is the basis for costs. Costs of other options are shown in Table 3-6. Table 3-14. Southern Area Effluent Disposal Costs
Effluent Capital Cost P.V. O+M Cost Total Cost Plan ~isposal* ($' Millions) ($ Millions)** ($ MilLions)
1. CW, L 2. CW, L 3. CW, L 4. CW, L 5. CW, L
6. CW, L 7. CW, L 8. CW, L 9. L 10. CW, L
11. L 12. CW, L 13. CW, L 14. CW, L 15. CW, L
16. CW, L 17. CW, L 18. CW, L 19. CW, L 2 0. CW
2 1. L 2 2. CW, L 2 3. L 24. CW, L 25. CW, L
26. CW, L 27. CW, L 28. CW, L 2 9. CW, L 30. CW, L
CW, L CW, L 3 3. L 3 4 L 35. CW, L ----- *CW = Coastal Waters * Negative values arise from L = Land income produced from crop 0 = Ocean production in land disposed Table 3-14. Effluent Disposal Costs (continued)
Effluent Capital Cost P.V. OfM Cost Total Cost Plan ~ispo sal* ($ Millions) ($ Millions) ($ Millions)
CW, L CW, L CW, L CW, L CW, L
CW, L CW, L CW, L CW, L
-- x~~ = Coastal Waters L = Land 0 = Ocean
**The outfall here assumes that treatment for ocean disposal is primary sedimentation plus chlorination. The costs for other outfall designs are summarized in Table 3-6. Inland Waters
Some of the less costly plans involve discharges to the inland waters via Calico Creek and the White Oak River. These plans would remove point source discharges from Newport and Beaufort and allow large buffer zones to be set up t~ define areas as waters to be used for wastewater treatment.
This result is not consistent with the goal of cleaning up the shellfish waters. Each shellfish area closed due to water quality infringements represent an economic loss. Although a large buffer zone can be set up to allow for dilution of the wastewater and dieoff of the coliform bacteria, there is no guarantee that the influence of the tides cannot cause hazardous conditions both inside and outside the buffer zone.
As the wastewater of the complex is primarily domestic in nature, with no dangerous industrial wastewater contributors, the problems of heavy metals, toxic substances and persistent organic chemicals are not significant. The major problems to be addressed are viruses and bacteria. Virus and coliform bacteria removal are significantly greater in the advanced wastewater process required prior to discharge to the inland sounds. Nevertheless, as shellfish are filter feeders, there can be no guarantee that the shellfish will not accumulate enough viruses or bacteria to be a health risk.
Shellfish are ingested raw, and are frequently obtained through unregulated transactions. The discharge of any wastewater to these waters, regardless of the treatment, will always constitute a potential health hazard.
It is difficult to place a cost on a threat to the public health. However, a cost can be derived from a loss of revenue due to closings of shellfish waters and a decrease in tourist trade. The basic idea that should be considered is that shellfish beds cannot be safeguarded from the bacteria and virus present in wastewater effluents. If bacteria and virus are present in the water, the shellfish will accumulate them. A coastal region dependent on its waters for shellfish, recreation and tourism would hardly elect to use these waters for wastewater treatment if other approaches are not more costly. Therefore, discharge to the inland sounds is not considered further.
Land Application
Although none of the options utilizing only land application of wastewaters are within the least costly plans, most plans depending on land application sites provide good adsorption and retention of virus and coliform bacteria, as well as BOD removel, nitrification, and nutrient removal through cropping. The effective depth to the water table is great enough that adequate treatment would be accomplished before the wastewater reaches the water table. After the wastewater reaches the ground water it will travel to the nearest surface water body, undergoing improvement enroute. Table 3-15. Total Costs of Alternatives
Effluent Capital Cost P.V. O+M Cost Total Cost Plan ~is~osal* ($ Millions) ($ Millions) ($ Millions)
1. CW, L 3 7 2. CW, L 3 7 3. CW, L 3 5 4. CW, L 36 5. CW, L 3 6
6. CW, L 3 7 7. CW, L 3 7 8. CW 37 9. L 40 10. CW, L 3 9
11. L 3 8 12. CW, L 4 1 13. CW, L 3 0 14. CW, L 3 1 15. CW, L 30
16. CW, L 3 1 17. CW, L 3 1 18. CW, L 3 2 19. CW, L 3 2 20. CW 3 3
21. L 3 9 22. CW, L 38 23. L 3 7 24. CW, L 40 2 5. CW, L 3 5
26. CW, L 2 7. CW, L 2 8. CW, L 2 9. CW, L 30. CW, L
31. CW, L 3 2. CW, L 3 3. L 3 4. L 35. CW, L
%CW = Coastal Waters 0 = Ocean L = Land Table 3-15. Total Costs of Alternatives (continued)
Effluent Capital Cost P.V. O+M Cost Total Cost Plan Disposal ($ Millions) ($ Millions) ($ Millions)
CW, L CW, L CW, L CW, L CW, L
CW, L CW, L CW, L CW, L
-CW = Coastal Waters 0 = Ocean L = Land
**All ocean disposal costs based on primary treatment plus chlorination. Other options are summarized in Table 3-6. A major consideration with this type of treatment is that no potable water wells should come in contact with the region of influence of the land application site. Many wells use the surfacialwater table as a water source, while municipal water systems tap the deeper acquifers that are not affected by the land application process, The ground waters of the perimeter of the application site would be monitored; however, efforts should be made to connect residences within the area of influence of the site to public water systems.
Ocean Discharge
The five least costly options for wastewater treatment and disposal use ocean discharge after primary treatment and chlorination for a major portion of the wastewaters from the area. Although primary treatment is not now acceptable as a treatment process by the EPA, this may change. The legal issue are discussed elsewhere in this report.
The major consideration in the design of an ocean outfall is the coliform bacteria concentration on the bathing beaches. The design is selected to meet these standards. It can be noted that in order to reach the beach fecal coliform bacteria concentration limit of 200/100 ml. a 1.3-mile outfall is required after secondary treatment with chlorination.
The health aspects of the wastewater discharges, their bacteria and viruses, are the important consideration. As long as industrial wastewaters and toxic substances are not present in the wastewaters, the effect of the discharges on the ocean aquatic life should be minimal. The nutrients may actually support fish life, as the ocean is deficient in nutrients. Furthermore, the least cost plans offer complete protection of the coastal sounds .
Comparison of Options
This study concludes that plan 55 B is most desirable for the Carteret- Onslow complex. This plan uses ocean discharge after primary treatment and chlorination for Morehead City and the Bogue Banks. The towns of Beaufort, Newport, Cape Carteret and Swansboro would each treat and dispose of their wastewaters separately to land application sites. This provides protection of the inland waters and is the cost effective and most environmentally sound option (See map 3-7).
As is the case for the northern area, the variations in total cost amongst the many options studied are not great. In any event, costs cannot be the sole basis for selecting amongst the options. Environmental considerations must play an important part in planning for wastewater management for the area. If the most environmentally desirable solution were also the most costly, then decision-making would be more difficult. Where the option that is most environmentally acceptable is no more costly, or even less costly, a decision is easier to reach, The most sensitive receiving waters in the area are the inland waters where shellfishing is severely affected by wastewater discharges. Any plan that would eliminate such discharges would be far more environmentally appropriate than plans which would include such discharges even if they meet the current water quality standards for discharge to shellfish waters. In the southern area, two other methods for disposal are not only feasible but are also attractive on a cost basis. These include ocean disposal and land disposal. Because of the distance of land for land application of wastewaters in the vicinity of these communities, the least costly and the most environmentally acceptable options are those that include ocean disposal for the coastal communities with land disposal for the inland communities in various combinations. This solution enjoys another significant advantage in that it permits a plan to be implemented in phases, with the inland communities addressing their problems independently of those on the coast and with the coastal communities not needing to wait on acequiescence of the inland communities for a common solution.
The economies of scale for the ocean disposal option are offset by the longer interceptor lines required for bringing the inland communities to the ocean.
Of the various options that incorporate both ocean and land disposal, plan 55 B appears to be most practical because it allows Beaufort, Newport, Swansboro and the Carteret County area to address their problems independently and the ocean disposal phase of the project serves only the Rogue Ranks and Morehead City. The inland communities would dispose of their wastewaters through land application while the ocean disposal option involves primary treatment and chlorination and an outfall 2.2 miles long.
Because each of the five elements of this plan can be implemented separately, the cost for each element may be considered separately. They are shown in (Table 3-16).
Table 3-16. Breakdown of Cost for Plan 558 ($ ~illions)
-_ ___l______- Effluent Sewerage System Treataent Effluent Discharge Capital P.V. O+M Location Discharge Treatment capital P.V. O+M Capital P.V. O+M Capital P.V. O+M Capital Total
Newpo r t Land Secondary + chlorination
Beaufort Land Secondary + chlorination
Cape Land Aerated Lagoon + Carteret chlorination
Swansboro Land Aerated Lagoon + chlorination W I Norehead City, CI1 and East and West Rogue Banks Ocean Prirna r y + chlorination
TOTALS
CHAPTER IV INSTITUTIONAL CONSTRAINTS AND OPTIONS*
Organizational Alternatives
Local organizational and financial arrangements assume central importance in community, water supply and wastewater management, despite the influence of federal and state laws, regulations, policies and financial assistance, it is at the local level that services are delivered, facilities are constructed and policies are made effective.
Each of the two areas covered by this study contains a number of local governments and most of them are currently involved in providing either water or sewerage services, or both. In each study area existing services must be expanded and improved to meet current requirements and projected growth. In this setting the organizational and financial arrangements are the keys to the development of effective water management programs and facilities and their efficient administration.
North Carolina statutes provide numerous options and great flexibility in organizing to provide water and sewerage services. The chief options are:
A city A county An interlocal contract A joint management agency A county service district A county water and sewer district A sanitary district A water and sewer authority A metropolitan water district A metropolitan sewerage district A private corporation A combination of the above
A brief description of each is given here.
1. Cities. City governments were the first local units to provide water and sewerage services in North Carolina and are still the local units principally involved in providing them. (N.C.G.S. 160A, Art. 9, 10 and 16.) Cities have a full range of financing powers: revenue and general obligation
*The subject matter of this section has been treated by W. J. Wicker in a number of publications over recent years. Some were issued under his name. Others were study reports without identification of original authors. This text reflects both an updating and rethinking of the subject, but not every word is freshly minted for this study. Because the study areas are located in North Carolina, the focus here is on arrangement possible in North Carolina. borrowing, taxation, the use of special assessments, and authority to impose all types of fees, rates, and charges. Rates imposed by cities for service are set by the city governing body and are not reviewed or approved by a state agency. Cities may provide the services both inside and outside their boundaries. (160A Articles 9, 10 and 16.)
Three limitations of the city as an organization for providing water and sewerage services may be present in some situations. First, the jurisdiction of the city may not cover all the area needing service. Second, if service is needed over a large area outside the particular city, the city government may not have the financial capacity to provide all the needed services. And third, insofar as the citizens of the area outside the city are concerned, water and sewerage services provided by the city are unregulated by either the State's Utility Commission or a local governing body responsive to them through the ballot box.
2. Counties. A few counties in North Carolina have been authorized to make expenditures for water and sewerage purposes for a quarter of a century, but not until 1961 were counties generally authorized to provide these services. Today, a county government's authority to operate, finance, and manage water and sewerage services is as broad as that of a city government, including authority to provide services inside cities and outside its own boundaries. (N.C.G.S., 153A, Arts. 7, 9and 15.)
Compared with a city, a county has some advantages. First, a single county covers a larger area than a city and, quite often, all the area that may require service from a single, physically connected water supply or sewerage collection and disposal system. And second, the county government's borrowing capacity is likely to exceed that of a city government or other unit located within its boundaries.
The major disadvantage facing a county is that it frequently has no existing facilities and no operating history. While counties have been active in financing services during the past fifteen years, only a few have any management experience, and some counties still do not view provision of water and sewerage services as a standard county activity.
3. Interlocal Contract. An interlocal contract is simply an agreement between two or more local units for one of them to undertake for both or all of them an activity that each is authorized by statute to carry out individually. Cities, counties, sanitary districts, other political subdivisions, and local governmental agencies are authorized by North Carolina's interlocal-agreement statute to enter into interlocal contracts. (N.C.G. S. 1538-278; 1608-461,)
An interlocal contract or agreement specifies what service or activity is to be provided, the contribution of each unit to its financing, and arrangements for operation and management. Personnel are employees of one or more of the participating governments. All property involved in the activity belongs to one of the units. The interlocal contract is much used in North Carolina in providing water and sewerage services. The typical agreement is one between a county and a city government in which the county shares in the cost of extending services to areas outside the city, Many agreements of this type call for some reimbursement of the county (and the city) from connection charges, rates, or other payments from customers served. Interlocal agreements are sometimes made to provide water and treat wastewater for two cities or for a city and county. Quite often, one unit simply purchases water or treatment services from another. An unusual local contract of this type is found in the Research Triangle area where the City of Durham operates a wastewater treatment facility constructed and owned by Durham County,
The interlocal contract is highly flexible. It permits the expansion of an existing capability--whether in plants and systems or in personnel--to serve the needs of two or more jurisdictions. A regional approach--perhaps involving an entire watershed--can be brought under unified management by this means. Economies of scale may be realized, and improved management may be achieved through combining needs for services. Since all areas of the state are covered by county governments and almost all counties have within their boundaries cities with existing water and sewerage services, interlocal contracts can be used in any area to create the optimal management jurisdiction for providing water and sewerage services.
This possible advantage also suggests a major limitation of the interlocal contract: the need for all the participating units to agree. It is sometimes difficult for units to agree on how costs and revenues should be shared or on joint policies for extensions, rates for service, or other aspects of operation and management.
The interlocal contract may also be viewed as something less than the ideal arrangement when concurrent future action is required. For example, suppose three cities agree to construct a joint wastewater treatment plant that will need future enlargement that must be financed through bond issues requiring concurrent approval by the voters of all three units. Failure of one unit's voters to approve could seriously delay the project and would probably require that alternate sources of capital be developed or arrangements for sharing costs be changed.
In short, an interlocal agreement works well where the units agree. Its chief shortcoming is that its structure does not assure the resolution of disagreement. It provides no single body capable of acting and in which a majority may be developed to take action.
4. Joint Management Agency. Cities and counties and other political subdivisions and agencies of local government are authorized by interlocal agreement to create a joint management agency to administer any undertaking each is authorized to carry out alone. The joint management agency is thus a special form of interlocal contract. Typically, in a simple interlocal contract, one unit administers the undertaking for all participating units. Where a joint management agency is used, a separate agency is created to administer the undertaking. Units that create a joint agency may confer on it any power, duty, right, or function needed to carry out the undertaking, except that title to all real property needed for the activity must be held by the participating units individually or jointly as tenants in common. The participating units that create a joint agency specify by resolution the composition of the agency, its powers and functions, matters relating to personnel, the duration of its life, procedures for modifying the agency's nature, methods of financing and apportioning costs and revenues, and other necessary matters. (N.C.G.S. 16OA-462, -463, -464. )
The advantage of the joint management agency is that it provides a single administrative structure that is independent from the administrations of the participating units. It may be especially useful where several units are cooperating and agreement for administration by one of them by contract would be difficult to reach.
The major limitation of the joint management agency is that it is not a unit of government. It has no independent taxing capacity, although it is empowered to issue revenue bonds and it could be authorized to establish rates, fees, and charges for water and sewerage services, for example, and to enter into contracts for construction and for the purchase of apparatus, supplies, materials, and equipment as necessary to operate water and sewerage systems.
These limitations can be overcome through other terms of an agreement. For example, three cities might each issue general obligation bonds to finance construction of individual wastewater treatment plants and then create a single joint management agency to operate them, Or again, a joint management agency might be used to construct and operate sewer systems for two cities, the cost of construction being met in one city from special assessments and in the other from connection fees. The participating units have great flexibility in working out specific arrangements.
50 County Service District. A county service district is an area within a county that is defined by the board of county commissioners and in which special-taxes are levied tb support certain activities. The activities supported through a service district must be either (a) activities not provided elsewhere in the county, or (b) a higher level of service for an activity than is supported throughout the county. Currently, water and sewerage services and five other functions may be provided in a service district. (N.C.G.S. 153A, Art. 16.)
A county service district is not a separate unit of government. The general county government is responsible for administering the functions of a service district, and all employees involved are county employees. An advisory body from citizens of the district could be created to advise the county commissioners on service policies within the district, but its role could be only advisory and all legal decision-making would remain with the county commissioners. The advantage of the service district arrangement is that it permits special or higher levels of particular services where they are needed with equity in financing, since a special tax is levied only in the area in which the services are provided. Since district functions are county functions, the full range of county financial and regulatory powers can he applied in the district and in connection with service district functions.
A service district need not be created except where additional property taxes must be levied to support the special district activity. In short, the county service district is designed to provide services with full or partial support from property taxes on less than a county-wide basis. Several counties in North Carolina have considered establishing a county service district to provide water and sewerage services but none has yet done so.
6. County Water and Sewer District. Acounty water and sewer district is, essentially, a county service district that is a separate unit of government, (N.C,G,S. 162A, Art. 6.) They were first authorized in 1977 at the request of a few counties that would have preferred to use a service district but were satisfied that the necessary countywide vote on bonds for service district purposes would fail. Bonds to finance facilities in a county water and sewer district, on the other hand, are subject to a referendum that is confined to voters of the district.
A county water and sewer district is created by the board of county commissioners after a public hearing, but without a petition or a referendum of the voters within the proposed district. Territory within a city or town may not be included within a water and sewer district unless the city or town governing body agrees.
Once created, a county water and sewer district may provide only water and sewerage services. It has substantially the same financing powers as a county. A district may levy property taxes, issue general obligation and revenue bonds, impose special assessments, and establish rates and charges.
The governing body of a district is the board of county commissioners of the county in which it is located. A district may employ its own administra- tive force, or contract for all personal services with the county, another unit of government or a private firm.
The major advantage of a county water and sewer district is that any vote on a bond issue for district purposes is confined to the district. Another advantage is the close coordination with general county government planning and programs that should result as the board of county commissioners also serves as the district governing body. The chief limitations are that each district must be created within a single county and there is no procedure for extending a district's boundaries after it is created.
7. Sanitary District. A sanitary district in North Carolina is an independent unit of government with limited powers, (N. C.G. S. 130, Art* 12- ) The state has some thirty sanitary districts, the largest being those that serve the Kannapolis and Roanoke Rapids areas. Most of the districts were organized to provide water and sewerage services, although they may also provide solid waste services and fire protection, and many do so. Probably most of the districts were organized in preference to incorporation as a city where citizens wanted water or sewerage services and not all the services and regulations (and accompanying taxation) that might be possible with status as a' city government.
With respect to water and sewerage services, a sanitary district's powers are generally parallel to those of a city or county. A sanitary district may issue both general obligation and revenue bonds, condemn land, establish rates and charges for services, levy property taxes, and, essentially, act with as much discretion and flexibility as a city or county except that it may not levy special assessments to extend water and sewer lines. A sanitary district also lacks a number of associated powers that cities and counties have. For example, it may not require the installation of water and sewer lines in new subdivisions, as it may not adopt subdivision regulations.
Sanitary districts may overlap cities (with approval of the city), and members of its governing board are elected.
A sanitary district does not receive federal revenue-sharing funds, community development grants or the local-option sales tax that may be levied by the county in which it is located. As sanitary districts are not authorized to build and maintain streets, they are not eligible for state street aid; nor do they share in beer and wine taxes and franchise taxes, as cities do.
Most sanitary districts are fairly small, perhaps reflecting the difficulty sometimes experienced in securing the necessary petition from a majority of either freeholders or resident freeholders in large areas and undoubtedly reflects the fact that most areas that develop in an urban fashion are incorporated as a city early in their development and the city provides the services that may be desired from a sanitary district.
As a sanitary district may overlap cities, it could be viewed as superior to a metropolitan water district in form when an organization with taxing power and general obligation bond issuing authority is needed in that it has an elected board (the metropolitan water district has an appointed board) and is thus more democratically responsive to its citizens. The difficulty of organizing a sanitary district that covers several existing cities may explain why the sanitary district has not been used in this state to provide these services to several cities.
8. Water and Sewer Authority. A water and sewer authority is a separate unit of government authorized to provide only water and sewerage services. (N.C.G.S. 162A, Art. 1.) Its powers with respect to these two services are extensive and make it an adequate organizational approach. Its chief financing limitations are that it cannot levy propery taxes or issue general obligation bonds, but it may impose special assessments. And as a special-purpose type of local government it does not receive federal revenue-sharing funds, community development grants, local-option sales taxes, or other state taxes shared with cities and counties. Its revenues are limited to those from water and sewerage operations and federal and state grants for these purposes.
The chief advantage of a water and sewer authority as an organizational approach is that it can bring together several units of government--typically cities and counties--when a multi-unit interlocal contract is politically impossible. Its appointive board makes it fairly responsive to the units that create it but only indirectly responsive to the citizens it serves.
Water and sewer authorities have been authorized by North Carolina statutes since 1955, but only three have been created--all since 1972. Of these three, only the Orange Water & Sewer Authority (OWASA), serving the Chapel Hill-Carrboro area, is currently providing services,
The water and sewer authority could also be used as a substitute for a joint management agency and have the advantage of permanent existence and the power, if necessary, to own real property. For example, after issuing general obligation bonds to finance the construction of water supply and wastewater treatment facilities, several local units might join in creating an authority to operate them, perhaps leasing the facilities to the authority under terms that would return to the creating units the funds necessary to meet debt-service outlays that arise from their bond issues, In this manner the general obligation borrowing advantages of a city or county could be combined with substantially independent and unified management advantages of an authority,
9. Metropolitan Water District. A metropolitan water district is an independent unit of government with power to levy property taxes and issue revenue and general obligation bonds for both water and sewerage purposes. These are the only services a MWD is authorized to provide, and its sewerage facilites may not duplicate those of a metropolitan sewerage district. (N.C.G.S. 162A, Art. 4.)
Amajor advantage of the MWD is its comparative ease of creation, requiring only resolutions of participating governmental units and a petition to the board of county commissioners from 15 percent of the resident voters of any unincorporated area included in its boundaries. Like the water and sewer authority, the MWD is an organizational approach that has extensive financing powers and brings together the territory of more than a single governmental jurisdiction.
Its financing limitations are similar to those of a sanitary district.
The metropolitan water district legislation was sought to meet needs in Buncombe County, and a number of its provisions are directed at circumstances peculiar to Buncombe. The MWD legislation, enacted in 1971, was modeled closely after the provisions of the metropolitan sewerage district legislation enacted in 1961. One significant limitation of the MWD is that it may be formed only within the boundaries of a single county, and, under current legislation, none of its revenues may be used for debt service on water and sewerage facilities of any of the creating governments--so that the creating governments with outstanding debt on their facilities would find it difficult to lease them to a' newly established metropolitan water district. Both of these features, of course, could be changed by the General Assembly.
The major advantage of the metropolitan water district, as compared with the metropolitan sewerage district, is that it is authorized to provide both water and sewerage services while the MSD may provide only sewerage services. The practice in North Carolina cities has been to combine water and sewerage operations in a single administrative department in order to use personnel, equipment, and other resources effectively.
While the legislation was sought by Buncombe County officials, no MWD has been created in Buncombe, but one has been created in Harnett County.
10. Metropolitan Sewerage District. Of all the organizational approaches considered here, the metropolitan sewerage district is the most limited in that it is authorized to provide only sewerage services. (N.C.G.S. 162A, Art. 5.)
The first MSD was organized in Buncombe County, and the state still has only three. The MSD is probably best suited to circumstances that require joint action by several units in constructing and operating wastewater treatment facilities. In Buncombe County, for example, the MSD builds, operates, and maintains sewer interceptors, treatment facilities, and outfalls. The sewer collection systems that empty into the MSD's interceptors are built and operated by the various political subdivisons included within the boundaries of the MSD. This limited role for the MSD also makes its financing powers quite adequate to its purposes.
The governing board for a MSD is appointed by the participating governmental units. A metropolitan sewerage district (unlike a MWD) may extend into more than one county; thus its taxing powers may be coextensive with its area of service--or, at least, its boundaries are not blocked by county lines.
As a special-purpose government, a MSD is eligible for state and federal grants for sewerage purposes but not for grants and taxes that are restricted to general-purpose governments, except for a share of the local option sales tax if it is in a county that distributes the tax proceeds on the basis of ad valorem taxes levied.
11. Private Water and Sewerage Companies. Community water and sewerage systems that serve the largest proportion of the population are publicly-owned. However, many private systems exist, generally serving fewer customers per system than the publicly-owned ones. (National Demonstration Water Project, 1978.) All private water and sewer firms are subject to regulation by the North Carolina Utilities Commission except those serving fewer than 10 customers and those nonprofit associations financed by the Farmers Home Administration. (N.C.G.S. 62-3(23.) The Commission reports that on December 31, 1978, 349 companies were subject to its regulation in the State. These companies operated 663 water systems and 55 sewer systems, serving an estimated 71,000 water customers and 13,000 sewer customers. Regulated systems are located in 76 of the State's 100 counties. (N.C. Utilities Commission, 1977.)
Private utilities are often established by developers of new subdivisions or communities and are frequently found in small communities where formal incorporation as a city, sanitary district, or other govermental unit is not wanted. Three towns and several small communities within the counties covered by this study are served by private water companies.
12. A Combination of Organizational Arrangements. The organizational arrangements for providing water and sewerage services in a region or area of substantial size may well-involve using a combination of organizational approaches.
As noted before, the most common organizational approach found in North Carolina is service by a single city government of the area within its boundaries and the urbanizing area surrounding it. Almost all county governments in North Carolina have also participated in providing services by interlocal contracts for extending water and sewer lines to parts of a county area while the other partner to the contract, the city, provides services elsewhere.
In Buncombe County services are provided through a combination of interlocal contract (city and county), metropolitan sewerage district, individual city action for many areas, and special water and sewer districts established in the county fifty years ago.
Moving eastward to the Research Triangle area, one finds services being provided by a combination of individual city action, joint action by two or more cities, joint action by a county and a city, action by a sanitary district, action by a water and sewer authority, joint action by a sanitary district and a water and sewer authority, and by a number of private corporations.
In the two coastal areas covered by this study water and sewerage services are now provided by private corporations, by individual cities, by a county, and through joint action of a county and several cities.
Each of the organizational alternatives has special strengths and weaknesses. In many larger areas the most effective arrangement may be a combination of approaches rather than any single approach. Fortunately, the existing legislation is flexible enough to permit arrangements to be developed for any area that are specially suited to its circumstances. Organizational Arrangements and Authority to Control Pollution from Nonpoint Sources
Increasing attention in recent years has been given to the control of water pollution from nonpoint sources in developing water quality plans. Various organizational approaches for providing water and sewerage services are outlined above. In selecting one of these approaches, or some combination of them, an important consideration would be their capacity or authority to also deal with pollution from nonpoint sources to attain better coordinated approach to reducing pollution from both point and nonpoint sources. For this reason, a brief review of the authority to control pollution from nonpoint sources by each of the organizational arrangements listed above is given here.
Only city and county governments have significant powers relating to the control of nonpoint sources of pollution. Through their general police powers and specific authorizations of regulatory powers in some instances, both of these general-purpose governments can take effective action affecting nonpoint pollution sources. (N. C.G. S. 162A-174, -183, -185, -192; 1538-121, -128, -132, -136.) In many cases, as with air pollution control, septic tank regulation, and building codes, state requirements establish minimum standards, and local regulations may not permit less than these standards. Often, as with air pollution and sedimentation, local ordinances must be submitted to a state agency for approval. Even so, the authority of cities and counties to take action is extensive.
Local bodies with regulatory powers cannot, in general, be created by interlocal agreements. City and county governments may, however, provide for the joint enforcement of regulations individually adopted. (N.C.G.S. 160A-461.) Thus, for example, a joint building inspection department may be established, and joint administration of a sedimentation ordinance could be arranged.
The county service district is not a separate unit of government and has no regulatory powers of its own. Its purpose is only to provide to a limited area of the county services that are financed by a special tax in that area. Three of its authorized purposes--solid wastes, recreation, and beach erosion-may affect nonpoint pollution. How these activities are undertaken by the county government for the district could be important to water quality.
A county water and sewer district has no general police powers and no authority to adopt regulations affecting nonpoint sources of pollution. Its governing body, however, is the board of county commiss~ionersand county governments have significant powers as noted above. This feature of the county water and sewer district should assure substantial coordination of point and nonpoint pollution control programs where a water and sewer district is used as the basic organizational approach.
The sanitary district has limited regulatory powers. It is expressly authorized to provide solid-waste services and engage in mosquito-control activites, and could adopt regulatory measures in connection with these functions. A sanitary district can probably adopt septic tank regulations, although this power is not entirely clear. On the other hand, clearly it can adopt regulations concerning the disposal of animal wastes. (N.C.G.S. 130-128.)
The remaining three public organizational alternatives discussed above--the water and sewer authority, metropolitan water district, and metropolitan sewerage district--have no regulatory powers not immediately related to the services they are authorized to provide and could not be used under current statutes to control pollution from nonpoint sources.
In brief, it appears that in the absence of significant additional legislation, the major local activity in controlling nonpoint sources of pollution in any water quality management plan developed must be entrusted in some fashion to city and county governments.
Standards for Evaluating Organizational Alternatives
Selecting a particular organizational arrangement or a combination of arrangements requires the balancing of values and the weighing of characteristics vital to effective management. Eight standards for evaluating organizational arrangements are suggested as being important and deserving of consideration. (Wicker and Heath, 1967.) No arrangement is likely to rate 100 per cent on every standard in any particular situation. The standards are listed here with brief descriptions and were used in selecting the suggested organizational arrangements outlined below for the two study areas. (Triangle J Council of Government, 1977.)
1, Jurisdictional Adequacy and Appropriateness. Is the organizational/ management area covered appropriate to the activity? Does the arrangement provide adequate legal powers over the area of activity? The various water management programs, activities, and facilities may, of course, have appropriately different jurisdictions.
2. Financial Capacity, To what extent does the arrangement make use of agencies with the capacity to finance in an equitable manner The construction and operation of facilities and the implementation of programs in accord with state and federal financing requirements?
3. Policy-Making Coordination. The management of point and nonpoint pollution control programs and facilities and water supply and distribution needs to be coordinated with other public services and regulations. This is especially true in the case of highways, recreation, fire protection, land use planning, housing, economic development, and solid waste collection and disposal. To what extent does the arrangement promote adequate coordination of all public policies and activities?
4. Nonpoint Coordination. To what extent does the arrangement promote and provide the necessary coordination between activities designed to control pollution from point sources and those concerned with nonpoint sources? While different agencies may have been assigned responsibility for controlling pollution from point source dischargers and septic tanks, it is important that both activities be coordinated.
5. Administrative Coordination. To what extent does the arrangement promote the necessary coordination between water management and other state and local governmental services and funrtions at the administrative level? For example, sewer lines are often located within street rights of way, and administrative coordination between the street and sewer activities is necessary.
6. Managerial Capacity. To what extent does the arrangement have the capacity to command the managerial talent necessary to plan and operate water supply and wastewater collection and treatment facilities? Size is probably the chief underlying factor with respect to this standard. Exceedingly small operations often do not have the resources to employ well-trained and experienced personnel.
7. Democratic Accountability. To what extent does the arrangement provide for the management of functions and activities in a manner that is democratically responsive and accountable to the citizens it serves? Does the arrangement adequately provide for citizen participation in the development of plans and policies?
8. Political Acceptability. To what extent is the arrangement acceptable to the elected and appointed officials who must give their approval before it can be implemented?
Institutional Arrangements
The governmental units in both study areas are relatively small and have limited financial resources. The recommended treatment and disposal systems demand some combining of communities in order to handle adequately all wastes and achieve an economically feasible installation. Most of the municipalities are too small to install and operate a wastewater collection and disposal system alone.
The controlling factors in both areas, among the ten listed above, would seem to be financial capacity, managerial capacity, and jurisdictional adequacy. Political feasibility, always a key factor in the real world, is not considered here since this is a research study. But the existing arrangements, reflecting the current meshing of all the factors, including political feasibility, has been considered. And because of the close relationship between water and wastewater, existing arrangements for water supply and distribution are considered in evaluating those that might be appropriate for wastewater management.
Northern Area. Existing water and wastewater facilities in Dare County are limited (See Table 4-1). Three of the municipalities--Kill Devil Hills, Manteo and Nags Head--operate water supply systems and were recently connected with a county system constructed to improve water supply and to provide water distribution services to unincorporated areas. The county sells water "wholesale" to the three municipalities and provides retail service to other areas of the county--Roanoke Island and the barrier islands--where service is , , feasible. The county government has thus become responsible for planning and developing water supply and transmission facilities and water distribution services outside the three municipaliti&.
Table 4-1. Number of Water and Sewer Customers of Local Governments in Dare County, July 1, 1977.
Unit Water Sewer
Dare County No System Kill Devil Hills No System Manteo 240 Nags Head No System Southern Shores (b)
aA county water system, under construction on July 1, 1977, was placed in operation in 1980. b~outhernShores was not incorporated until 1979. It will be served by the county water system.
The Dare County Regional Water Supply System is an operating department of the county government. Its head reports to the county manager and the Dare County Board of Commissioners is the policy-making body for the system.
The initial capital requirements for the County's water facilities were met by a combination of federal and state grants and a federal loan. Debt service on the loan and all operating expenses are to be met from a combination of user charges and frontage assessments and connection charges for distribution line extensions. Capital and operating costs within the towns are to be met from a combination of frontage assessments, subdivision improvement requirements, connection charges and user charges.
In Dare County only Manteo currently provides a wastewater collection system. Table 4-2. ' Assessed Valuations, Tax Rates, Debt and Debt Ratios for Local Governments in Dare County, 1977 and 1978.
Assessed 1977-78 Indebtedness Debt
a Unit Valuation, 1977-78 Tax Rate July 11, 1977 Ratio
Dare County $308,926,000 $ .44 $6,480,000 2.10% Kill Devil Hillsa 63,361,000 .44 580,000 .91 ~anteob 4,998,000 1.40 230,000 4.62 Nags Head 77,825,000 .48 710,000 .9 1 Southern ShoresC ------
Note: The most recent property revaluation was in 1975. The debt ratio is indebtedness expressed as a per cent of the unit's assessed valuation. aIn an election on May 2, 1978, Kill Devil Hills voters authorized issuance of $875,000 in water bonds and $225,000 in municipal building bonds. If all of these bonds are issued, the total indebtedness will be in the order of $1,960,000 and the new debt ratio will be about 3.1%.
b~nan election on February 15, 1977, Manteo voters authorized issuance of $700,000 in water bonds and $150,000 in sewer bonds, none of which have been issued. Manteots debt ratio dropped to 2.5% in February, 1978, with an annexation that doubled its size and increased its assessed valuation to $9,400,000. =Southern Shores was not incorporated until 1979.
Except in Manteo, tax rates of the various jurisdictions are low, but so is their borrowing capacity (See Table 4-2). Only the county government (or some combination of the beach municipalities) would have the financial capacity to construct a wastewater collection and disposal system. Given the limited populations to be served, a management system that matches in jurisdiction that of the physical system recommended is needed. An arrangement that parallels the water arrangement already in place would seem to be the most appropriate. This approach would enable a single county department to become responsible for wastewater disposal and for collection in the unincorporated areas where levels of development make the service feasible. The collection systems within the municipalities could be constructed and maintained by the towns--paralleling the water distribution arrangements--or the entire operation could be assumed by the county government. The advantages of county government management of the principal wastewater facilities are substantial. It is organized already--no new agreements or creations are necessary. The jurisdiction covers all the area that can be served, both incorporated and unincorporated, and all the area that will be served in the future as well as with initial facilities. Its governing body is elected by all the citizens and is thus democratically responsible. The county has the financial capacity to borrow the necessary funds. Since the county is already operating a county-wide water system, the opportunities for combined service with more efficient use of both personnel and equipment are present. The county has a full range of regulatory powers-- land use regulation, solid waste control authority, and the like--that could mesh with policies on wastewater to guide and protect growth and the fragile environments of the coastal area. Construction and operation of the collection systems within the towns could be either by the respective towns, or the county's arrangement could include this phase of the operation as well.
Table 4-3. Number of Water and Sewer Customers of Local Governments in Carteret County and Swansboro, July 1, 1977.
Unit Water Sewer
Carteret County No System No System Atlantic Beach 2,000 No System Beaufor t 1,550 1,550 Cape Carteret No System No System Emerald Isle 1,370 No System Indian Beach No System No System Morehead City 1,790 Newport 650 Pine Knoll Shores No System Swansboro
Note: The cities of Beaufort, Morehead City, Newport and Swansboro operate municipal water systems and sewer systems. In Atlantic Beach, the water system has been privately operated, but a municipal system is being established. The Emerald Isle and Pine Knoll Shores systems are private. Southern Area. The existing organizational and financial arrangements in the Southern area involve the municipalities and private companies. Carteret County has been involved in preliminary studies for water and wastewater, but does not own and operate any facilities. Beaufort, Morehead City, Newport and Swansboro own and operate municipal water systems. The system serving Atlantic Beach is privately owned and inadequate. The Town is constructing a new system and will become the water supplier in 1981. Private community water systems serve Emerald Isle and Pine Knoll Shores. Similar arrangements are found with respect to wastewater, except that no community wastewater systems have been constructed to serve Bogue Banks. On the mainland the towns of Beaufort, Morehead City, Newport and Swansboro now have wastewater systems that all need improvements.
Table 4-4. Assessed Valuations, Tax Rates, Debt and Debt Ratios for Carteret County Local Governments and Swansboro, 1977 and 1978.
Assessed 1977-78 Indebtedness Debt Unit Valuation, 1977-78 Tax Rate July 11, 1977 Ratio
Carteret Count Atlantic Beachr Beaufort Cape Carteret Emerald Isle Indian Beach Morehead City Newport Pine Knoll Shores Swansboro
Debt Ratio is the outstanding debt expressed as a percent of the unit's assessed valuation. The most recent revaluation of property was in 1976 for Swansboro and 1973 for all other jurisdictions.
aCarteret County voters approved a $7,150,000 bond issue for schools on May 2, 1978. b~tlanticBeach votets approved a $1,600,000 bond issue for water improvements on May 2, 1978. The recommended wastewater disposal plan outlined in Chapter 3 calls for ocean disposal for systems serving Morehead City and the Rogue Banks, with various options for arrangements involving Beaufort, Cape Carteret, Newport and Swansboro--generally options that only involve action by the individual units. Because they have existing operations and appear able to finance the improvements individually, and because individual action may be the easiest to mount, a continuation of the present arrangements for these towns is suggested.
The cost of the ocean disposal facilities and the need to provide Bogue Banks with a sewage collection system that will cover several small municipalities suggest that some form of collective action for both financing and for management is needed. None of the individual towns on Bogue Banks is in a position to become the central service provider for the entire area. Four general approaches to the organization and financing appear to merit consideration.
A. County B. County water and sewer district C. Interlocal contracts D. Metropolitan water district
A. County. The county government is on the scene and already organized. It has the capacity to finance the ocean disposal facilities and to construct the sewage collection system on Bogue Banks and to establish and operate all Bogue Banks facilities. If the local financing requirements demanded some support from local taxes, the county could form a county service,district covering all the Bogue Banks area and supplement user charges, fees and special assessments for sewer line extensions with local property taxes. Under this alternative, the county would accept the discharge from Morehead City under a contract. Atlantic Beach also has a water system and could be served under contract (rather than directly) in the fashion of Morehead City.
Since Morehead City would be involved in the ocean disposal, the county could contract with Morehead City for management of all the systems as an alternative to establishing a separate county department. The financing would be the same in either case.
County water and sewer district. In some cases county voters have been unwilling to approve countywide bond issues for some relatively small portions of the county. If countywide approval of bonds for improvements to serve Morehead City and the Bogue Banks proved impossible, a county water and sewer district might be organized. This would allow the vote on borrowing to be confined to the district. Otherwise, the financing and management options would be the same for a county water and sewer district as with direct county management since the board of county commissioners is the governing body of a county water and sewer district.
Interlocal contracts. The ocean disposal facilities and a sewage collection system for Bogue Banks could also be provided by a series of interlocal agreements between all the municipalities involved. For example, each municipality might be responsible for constructing and maintaining its own sewage collection system and contracting with, say, Morehead City for disposal. Morehead City, as the largest of the units and the one with an existing staff, might be responsible for constructing and operating the disposal facilities under contracts with the other municipalities.
The disadvantage of the interlocal agreement approach is the fairly large number of contracts that would be needed. Moreover, the agreements would also need to include provisions for changing arrangements and financing levels later if conditions change. Securing agreement on all these matters could be difficult.
Metropolitan water district. The final approach suggested for consideration is the creation of a new unit of government--a metropolitan water district. A metropolitan water district that covered all of Bogue Banks and Morehead City would have the financial capacity to become responsible for wastewater collection and disposal. It could also become the operating agency, or it could contract with, say, Morehead City to operate all facilities. Its financing could involve the same approaches available to the county, except that special assessments could not be used to finance the installation of new sewer lines.
These arrangements, involving Morehead City and Bogue Banks, could also be extended to cover all the municipalities in Carteret County. Swansboro could contract for management services under all four possible arrangements.
Direct responsibility by Carteret County for all the operations would appear to be the most advisable arrangement if it should prove to be politically acceptable. Should county assumption of full responsibility prove impossible, the other approaches, in the order listed, would seem to be the most appropriate organizational and financing arrangements. CHAPTER V LEGAL CONSIDERATIONS*
Legal Protection of Sources of Water Supply in North Carolina
Sources of public water supply in North Carolina can be protected or augmented under at least ten different statutory proceedings: -- First, by establishment of a capacity use area under G.S. 143- 215.13. Under the same law the Environmental Management Commission can prohibit water withdrawals in an area found to be in a condition of generalized water depletion, or prohibit discharge of pollutants in an area found to be in a condition of generalized water pollution. G. S. 143-2lS.l3(d). - - Second, by designation of an area of environmental concern covering public water supply watersheds or aquifers. These designations are made by the Coastal Resources Commission under the Coastal Area Management Act. G.S. 113A-113(b)(3). These powers can only be exercised within the 20 coastal counties. - - Third, by a directive to halt or curtail the discharge of wastes in an area found to be in a generalized condition of water pollution that causes imminent danger to public health. These directives are formalized by orders of the Secretary of Natural Resources and the Governor. G.S. 143-215.3(12). - - Fourth, by withholding the granting of waste discharge permits in an area found to be in a condition of generalized water pollution. These actions are taken by order of the Environmental Management Commission. G. S. 143-215.3(8). - - Fifth, by denying or conditioning the grant of an Environmental Management Commission permit for disposal of wastes into waters classified as a source of public water supply and so close to the water supply intake as to adversely affect the public water supply. G.S. 143-215.1(a). - - Sixth, by procedures administered by state and local health authorities for the protection of public water supplies. G.S. Ch. 130, Art. 13D. These procedures embrace the general oversight and protection of public water supplies as well as more specific responsibilities under the N.C. Drinking Water Act of 1979. - - Seventh, by denial of an Environmental Management Commission permit under the Well Construction Act for construction of a well with a design capacity of 100,000 gallons per day or greater, or for wells in areas found by the Commission to need protection of ground-water resources. G. S. 87-76.
*This discussion is partly derived from two previous papers by Milton Heath: Some Current Legal Issues in North Carolina Concerning Diversion of Water for Public Water Supplies and Related Matters" (Southeast Conference on Legal and Administrative Systems for Water Allocation, Blacksburg, Va.; April 19, 1978); and "Some Emerging Water Law Issues in North Carolina" (North Carolina Water Management Luncheon, U.N.C. Water Resources Research Institute, Raleigh, North Carolina, May 10, 1978). -- Eighth, by emergency diversion of water, approved by the Environmental Management Commission, following the declaration of a water emergency by the Governor. G.S. 143-354. -- Ninth, by exercise of a right of withdrawal of impounded waters under the Stored Water Act. G.S. 143-215.44 et seq. - - Tenth, by denying or conditioning the grant of a certification under the Dam Safety Law in order to maintain minimum stream flow requirements. G. S. l43-215.25(4).
All of these statutes may function in some circumstances as vehicles to protect water supply sources. And additional requirements and restrictions are found in federal legislation, such as the Safe Drinking Water Act and Section 404 of the 1977 Federal Clean Water Act.
Each of the statutory procedures pertinent to coastal wastewater management is described in greater detail below. --Areas of Environmental Concern (AEC1s) -for Public Water Supply vat--fers - --under CAMA [G.S. 113~-113(b)(3)] The Coastal Area Management Act seeks to establish a comprehensive plan for the protection, preservation, orderly development and management of the coastal area of North Carolina. The three main features of the act were designed to insure that the following will have been accomplished by 1978: First, that each of the 20 coastal area counties will be covered by a ---land use plan, preferably prepared by local government, and in basic harmony with the plans adopted for the other 19 coastal area counties. This was achieved in 1976. Second, that all critical areas which need to be considered for protection and possible preservation in each county will have been designated so-called --Areas of Environmental Concern or "AEC1s". The AEC's have been adopted, effective July 1, 1977. Third, that any proposed development, change or other use of land within any of the designated areas of environmental concern will be subject to review by means of development permits under the terms of this act, beginning March 1, 1978.
With respect to AEC's, the Commission exercised its powers by classifying as AEC1s a number of environmentally sensitive areas, among which were two types of public water supply lands: small surface water supply watersheds and public water supply well fields, The Commission designated four specific examples of these AEC classes, including two in Dare County. The effect of this action is that permits will be required for developments within any of these water supply AEC's. Orders to Correct Generalized Conditions --of ~ateF~ollution [G. S. 143-215.3(8) and (12) 1 The Environmental Management Commission has authority under the Capacity Use Areas Law to prohibit new or increased wastewater discharges in an area of generalized water pollution. There are two additional statutory avenues for responding to such conditions. Under G.S. 143-215.3(8) the Commission may suspend the granting of water pollution control permits, after holding hearings and making appropriate findings. And under G.S. 143-215.3(12), if the generalized condition of water pollution is also found to be causing imminent danger to the public health or safety, the Commission may declare an emergency and the Secretary of the Department of Natural Resources with the concurrence of the Governor may order an immediate reduction or cessation of the con-tributing waste discharges, subject to the results of a hearing to be held within 24 hours by the Commission. Permits -for Disposal of Wastes into Waters Classified as a Public Water SUP~YSource IG.S. 143-215.l(a) 1
G.S. 143-215.1(a) spells out the requirements for permits to carry on various activities that may pollute the waters of the state--by initiating a new waste discharge into these waters, by increasing or changing the nature of a discharge, by constructing or altering a waste treatment facility, etc. It establishes a special procedure for the protection of waters classified as sources of public water supply, where the Department of Human Resources has advised the Environmental Management Commission that the disposal is close enough to a public water supply intake to have an adverse effect on it. No permit may be granted for waste disposal into any such waters until the Commission for Health Services of the Department of Human Resources has been given an opportunity to review the plans and specifications and has advised the Environmental Management Commission in writing of its approval of the proposed waste disposal. In effect this gives the State health authorities a veto over waste discharges in the vicinity of public water supply intakes.
Public Health Procedures for Protection of Public Water s-en.S9Chapter 130,~ticle13D) The State and local health authorities traditionally have been responsible for the general oversight and protection of public water supplies.* Although some of this responsibility now resides in the state's general water pollution control agency (the Environmental Management Commission), the health authorities remain the lead agencies in this field. Their functions include the following:
*under the definition of the public health code, as recently modified by the Drinking Water Act, a "public water supply" is a system the provides piped water to the public for human consumption and serves 15 or more service connections or regularly serves 25 or more individuals. G.S. 130-166.41(12). (1) General oversight in the Department of Human Resources of public water supply sources; and rulemaking power in the Commission for Health Services governing drinking water quality and the location, construction and operation of water supply systems. (G.S. 130-166.43 to -166.45). (2) Review and approval, through the Department of Human Resources, of all plans and specifications for constructing and altering a water supply system, G.S. 130-166.45. This authority encompasses giving advice concerning the location, construction and operation of public water supply systems; requiring compliance with drinking water regulations; requiring systems to be designed adequately for anticipated needs; requiring engineers to design plans and specifications; and requiring developers to submit evidence of their proposed maintenance and operating arrangements. (3) Approval by the Health Services Commission of waste discharges above public water supply intakes into waters classified as a public water supply source, as noted under the previous heading. G.S. 130-166.53(5), 143-215.l(a). (4) Responsibility to carry out the state's functions under the Federal Safe Drinking Water Act. These responsibilities are spelled out in the North Carolina Drinking Water Act of 1979. G.S. Chapter 130, Article 13D.
Septic Tank ~e~ulation*
Four statutes govern the installation of septic tank systems in North Carolina. Three of these are contained in G.S. Chapter 130: G.S. 130-160, the basic authority for state regulation of septic tanks; G.S. 130-17, the basic authority for local regulation of a variety of public health matters; and G.S. 130-166.22 to 130-166.33, the Ground Absorption Sewage Disposal Act. The fourth is contained in G.S. Chapter 143, Article 21, the statutes concerning control of water pollution by the Environmental Management Commission.
This review is divided into five sections: first, the general concepts of coverage, jurisdiction and procedure; second, detailed statutory procedures under the Ground Absorption Sewage Disposal Act; third, Health Services Commission regulations; fourth, enforcement under the health laws; and fifth, Environmental Management Commission laws and regulations.
General Concepts of Coverage, Jurisdiction and Procedure
Coverage. G.S. 130-160(a) establishes the basic requirements of state law for approval of septic tanks. Those requirements are that:
*This section was co-authored by M. Patrice Solberg. 1. Any person "owning or controlling any single- or multiple-family residence, place of business or place of public assembly" must provide a sanitary system of sewage disposal.
2. The system must be one of two kinds: a) A connection to a public or community sewerage system. b) An approved privy or septic tank system. Jurisdiction. G.S. 130-160(a) provides the basis for sharing of jurisdiction over septic tanks among agencies at the state level. G.S. 130-17(b) and 130-160(b) provide the basis for sharing of jurisdiction between state and local agencies. The basic jurisdictional rules laid down by these sections are as follows: 1. Disposal systems with 3,000 gallons or less capacity -and which do not discharge into surface waters are subject to rules and regulations of the Commission for Health Services.
2. Disposal systems with a capacity of more than 3,000 gallons and those of any size that discharge into surface waters are subject to the rules and regulations of the Environmental Management Commission, except that the Commission must delegate to local health departments regulation of discharges of less than 1,000 gpd from single family dwellings.
3. Local boards of health --may not adopt rules and regulations covering disposal systems under the jurisdiction of the Division of Environmental Management.
4. Local boards of health share jurisdiction with the State's Commission for Health Services in the manner provided in G.S. 130- 17(b); G.S. 130-160; G.S. 130, Art. 13C. As set forth below (p. 5-6), the local boards may:
(a) Adopt comprehensive septic tank rules with state approval, under certain circumstances; or (b) Adopt local modifications that are stricter than the state rules to meet peculiar local conditions or in emergencies.
Classes of Rules and Regulation. In each county, the regulation of non-discharging septic tanks with 3,000 gallons capacity or less is accomplished by a combination of selected state statutes and rules and regulations adopted under law. The rules and regulations applying in each county are one of three classes:
1) Comprehensive stateoide rules and regulations promulgated by the Commission for Health Services. These became effective for all counties on July 1, 1977, and apply and are enforced by local health officials unless modified or displaced as outlined below. 2) Comprehensive rules and reguZations promulgated by the Commission for Health Services with modifications in partCcuZar features because of emergency or peculiar local condition. The local modifications are authorized by G.S. 130-17(b). They may not be less stringent but may be more stringent--than the rules of the Health Services Commission.
3) Comprehensive ZocaZ rules and regulations. These may be adopted by a local board of health after a finding by the Commission for Health Services that the proposed local rules and regulations are substantially equivalent to those of the Commission and that they are sufficient to safeguard the public health. A 1977 law, G.S. 130-160(b), sets forth the procedure for substituting local comprehensive regulations for the state's regulations.
Questions have arisen concerning the interpretation of the 1977 amend- ments to G.S. 130-160(b) in conjunction with the pre-existing provisions of G.S. 130-17(b). One position is that if comprehensive local regulations are adopted and approved under the new G.S. 130-160(b), they must be at least as strict as, but may be stricter than, the stateqs regulations; only individual rule modifications of state regulations by local boards have to be justified by peculiar local conditions or an emergency, as provided in G.S. 130-17(b). (This is the position proposed by the staff of the Health Services Commis- sion.) The other, more conservative position is that -any local regulations that are more stringent than state regulations must meet the 5 17(b) "emergen- cy or peculiar local condition" test, whether these local fegulations are supplementary individual regulations or part of a comprehensive set.
If a local board wants to include in its comprehensive regulations provisions concerning subjects not dealt with in the state regulations, there is a plausible argument that the limitation of 5 17(b) does not apply. On this reasoning, a local board could include in its comprehensive regulations provisions or subjects not covered by the state regulations, such as lot sizes, and stepdowns, without meeting the "emergency or peculiar local condition" test.
Local Regulations: Developments Under 1977 Amendments to G.S. 130-160
As of November, 1980, the Health Services Commission had approved compre- hensive local regulations under G.S. 130-160 for four individual counties (Cabarrus, Durham, Orange, and Pamlico), and one multi-county district (Rutherford, Polk, McDowell). Several other applications were pending for Commission review.
Comprehensive regulations that have been approved by the Commission include, in more than one county or district, provisions not covered in State regulations (such as minimum lot sizes and construct~ontechniques like step-downs). Approved local regulations also include some provisions stricter than comparable state provisions, such as sizing of systems. No firm conclusions can be drawn at this time about the basis of the Commission's approval of local regulations that in some respects are stricter than their state counterparts. As far as the records indicate the Commission's approval could be based on all or any of the following grounds:
(1) An assumption that the local board could make or had already made and recorded a 5 17(b) case of "emergency or peculiar local conditions." (2) An assumption (as suggested by the Commission's staff) that the Commission is authorized by amended G.S. 130-160(b) to approve comprehensive local regulations that contain provisions that are stricter than (though not more lenient than) state provisions. (3) An assumption, that in the particular situation, litigation contesting the action was quite unlikely and therefore an acceptable risk,
Detailed Statutory Procedures: Ground Absorption Sewage Disposal System Act
The Ground Absorption Sewage Disposal System Act of 1973 (G.S. 130-155.22 to 130-166.33) requires that "improvements permits" and "certificates of completion" be obtained for "dwellings" and mobile homes intended to be used as dwellings (other than those in a mobile home park) that are situated in an area not served by a public community sewage disposal system before certain activities may be carried on there. Unlike G.S. 130-160, it does not apply to places of public assembly; nor does it apply to areas not served by community sewer systems when acceptable plans for installing community sewage systems are presented to the local health department and the North Carolina Environmental Management Commission. Developers must certify that the system will be installed before they allow buildings in the area to be occupied.
Before anyone can begin to construct or relocate a dwelling or mobile home intended to be used as a dwelling (other than one in a mobile home park), he must obtain an improvements permit from the local health department. The department issues the permit when it has determined, after a field investiga- tion of the area, that the system can be installed in compliance with the applicable regulations. The department must consider the character and porosity of the soil, percolation rate, water table, depth to rock or other impervious formations, and the location or proposed location of water-supply wells.
The statutes specifically prohibit "covering" a septic tank system with soil until the local health director determines that the system as installed complied with the applicable rules. It is unlawful to occupy a dwelling or mobile home intended to be used as a dwelling until this-certificatehas been issued.
A person who is denied an improvements permit or a certificate of completion has a right of appeal, though it is not clear whether that appeal should be filed with the local board of health or with a state hearing officer under the Administrative Procedure Act. A major problem in enforcing the septic tank regulations is that builders who are unaware of the regulations invest large sums of money in property where septic tanks cannot be installed and put great pressure on sanitarians to approve the unsuitable systems: The more money invested, the greater the pressure. To stop builders from making large investments on unsuitable property before learning that septic tanks cannot be approved, early local regulations required plumbing permits to be withheld until a sanitarian had inspected the property, As these permits were obtained early in the construction process, the builder learned whether a septic tank could be installed before he invested too much money in the property.
The Ground Absorption Act, in turn, provides that with regard to conventional dwellings, no permit for electrical, plumbing, heating, air conditioning, or other construction, location, or relocation activity can be issued before an improvements permit is issued. Other permits such as zoning permits, can be required before the improvements permit is issued, Also, if location or relocation of a mobile home is proposed, no permit for electric- ity, plumbing, heating, air conditioning, or other construction, location, or relocation activity can be issued until the certificate of completion has been issued. Finally, it is unlawful for any electric current to be supplied until the official electrical inspector certifies to the electrical supplier that the required improvements or completion permits have been issued.
Violations of any law governing improvements permits or certificates of completion are misdemeanors punishable by a fine of up to $200.
Health Services Commission Regulations. Effective July 1, 1977, the Commission for Health Services enacted rules governing ground absorption sewage disposal systems. The state rules req;ire a &itten permit to be obtained from the local health department before a sewage disposal system or privy is installed, required, or renovated. Anyone who is in the business of constructing, installing, or cleaning septic tanks must register with the local health director in each county where he operates before he constructs or installs septic tanks or collects and disposes sf septic tank contents unless he is the owner, tenant, or manager of the place where he is doing the septic tank work.
The state rules require the health department to determine whether a site is appropriate for the proposed septic tank system before it issues the required permit for the installation of a septic tank system. These rules classify sites as suitable, provisionally suitable, or unsuitable. The classification determines whether a conventional septic tank system may be installed and, if so, how many gallons per square foot of septic tank effluent the site may receive per day. The classification must be based on a site evaluation of the following factors: topography, soil character (including texture, structure, depth, restrictive horizons, and drainage), ground-water elevation, depth to impervious stratum, and soil percolation rate and porosity.
Those rules also contain minimum horizontal distance requirements providing how far septic tanks must be from certain structures and physical features, such as streams and marshes; but a "grandfather clause" excepts certain tracts that are too small to meet the requirements for a septic tank system and were platted or deeded as of July 1, 1977. Also, there is a blanket exemption for ground absorption sewage disposal systems in use or for which a valid permit has been issued before July 1, 1977. Finally, if the system falls into disrepair or has been disconnected or abandoned for any reason (except for destruction by fire), the system may not be used again unless it meets the provisions contained in the state rules with certain exceptions.
Enforcement.
1. The local board of health is responsible for enforcement of rules and regulations (whatever the source) and for issuing improvements permits and certificates of completion under the Ground ~bsoi~tibnSewage ~is~osalAct of 1973.
2. City and county building inspection officials are required by the Ground Absorption Sewage Disposal Act not to issue certain building permits until the improvements permit or certificate of completion (whichever is applicable) has been issued.
3. Electrical suppliers are required by the Ground Absorption Sewage Disposal Act to withhold electrical service until required permits are issued.
Laws and Regulations Governing The Environmental Management Commission
In recognition of federal requirements administered by EPA, North Carolina law places responsibility on the Environmental Management Commission (EMC) for waste disposal systems that discharge to surface waters, so that a single state agency will be in a. position to administer the NPDES permit system. As noted previously, North Carolina law also draws two jurisdictional lines based on capacity of systems:
1, Under G.S. 130-160(a), all system larger than 3,000 gallons capacity, whether or not they discharge to surface waters, are subject to approval under the rules and regulations of the EMC adopted pursuant to G,S. Chapter 143, Article 21. 2. G.S. 143-215.l(c)(2)b establishes one minor exception to the general rule on jurisdiction over discharging systems: The EMC must adopt a regulation delegating to local health departments responsibility for issuing permits for discharges of less than 1,000 gpd from single family dwellings. The fact that this is accomplished by EMC regulation, rather than directly by statute, retains some potential surveillance and control in the EMC.
Discharging systems under EMC jurisdiction are governed by the mixture of federal and state regulations that apply to the NPDES permit system. As these regulations are generally more familiar than the regulations of the health agencies, they are not described here. Non-discharging systems that are larger than 3,000 gallons design capacity are governed by regulations of the Environmental Management Commission that became effective February 1, 1976. (N.C. Administrative Code, Title 15, Chapter 2, $1 .0300-.0306). A residence, place of business or place of public assembly subject to these regulations must be provided either with a septic tank system that meets the regulations, an approved sewer system connection, or privies that meet the requirements of the Health Services Commission.
In general the EMC regulations follow the approach of the Health Services Commission regulations with respect to site evaluation and minimum horizontal distances from structures and physical features. In many instances the two sets of regulations are identical. One important difference is that the EMC regulations, unlike the Health Services Commission regulations, contain no grandfather clause.
The Department of Natural Resources and Community Development is responsible for enforcement of the EMC regulations, with the assistance of the Attorney General. Generally, the criminal sanctions for violation of EMC regulations and of the statutes EMC operates under are more severe than the comparable sanctions under the health laws and regulations. In addition, EMC is authorized to assess civil penalties for violations under its laws and regulations, a power not possessed by the Health Services Commission. Both EMC and the health agencies are authorized to seek injunctions.
Regulation of Land A~~licationof Wastewaters
The 1977 Federal Clean Water Act and proposed EPA rules thereunder have resolved any doubts that may have existed under previous laws and regulations concerning the acceptability under federal law of the wastewater treatment techniques known variously as "land application," "land disposal" and "land treatment ." The new law and regulations clearly encourage the use of land application techniques as a preferred method of achieving the clean water goals of the Clean Water Act. Section 201(g)(2) requires that applicants for treatment grants satisfactorily demonstrate that alternative waste management techniques have been evaluated and Section 201(g)(5) makes plain that these alternative techniques include land treatment. It provides:
(5) The Administrator shall not make grants from funds authorized for any fiscal year beginning after September 30, 1978, to any State, municipality, or intermunicipal or interstate agency.for the erection, building, acquisition, alteration, remodeling, improvement, or extension of treatment works unless the grant applicant has satisfactorily demonstrated to the Administrator that innovative and alternative wastewater treatment processes and techniques which provide for the reclaiming and reuse of water, otherwise eliminate the discharge of pollutants, and utilize recycling techniques, land treatment, new or improved methods of waste treatment management for municipal and industrial waste (discharged into municipal systems) and the confined disposal of pollutants, so that pollutants will not migrate to cause water or other environmental pollution, have been fully studied and evaluated by the applicant taking into account subsection (d) of this section and taking into account and allowing to the extent practicable ' the more efficient use of energy and resources. [33 U.S.C. 1281(g)(5). Emphasis added.] Implementing regulations proposed by EPA on April 25, 1978, indicate that land application systems can be classified as innovative technologies, and require an analysis of innovative techniques for all facilities plans initiated after September 30, 1978. (43 Fed. Reg. 17691, 17694.) The definition of land eligible for inclusion in grants for treatment works has been broadened by the 1977 Act and the proposed rules to include land used for storage of treated wastewater in land treatment systems prior to land acquisition, and land acquired for composting sludge. (33 U.S.C. 1292(2)(A); 43 Fed. Reg. 17699, 17703, April 25, 1978.)
Planning for Coastal Land Development and Environmental Protection Under the North Caroline Coastal Area Management Act The Legislation and its Background
The basic objective of the Coastal Area Management Act (CAMA) is to establish a comprehensive plan for the protection, preservation, orderly development and management of the coastal area of North Carolina. The thrust of the act is to establish a cooperative state-local program of coastal land management, with planning a local responsibility, critical area designation a state responsibility, and permit-letting and enforcement a joint responsibility. The three main features of the act were designed to insure that the following would be accomplished by 1978: First, that each of the 20 coastal area counties will be covered by a land use plan, preferably prepared by local government, and in basic harmony ---with the plans adopted for the other 19 coastal area counties. This was achieved in 1976. Second, that all critical areas which need to be considered for protection and possible preservation in each county will have been designated so-called Areas of Environmental Concern or "AEC6ss." The.AECfs have been adopted, effective-- July 1, 1977.
Third, that any proposed development, change or other use of land within any of the designated areas of environmental concern will be subject to review by means of development permits under the terms of this act. Generally local government handles permits for minor developments and the Coastal Resources Commission (CRC) handles permits for major developments. The permit system became operative March 1, 1978.
CAMA was designed to enact into law a strong role for the CRC. To achieve this, the General Assembly gave the CRC itself not only general pol'icy-making responsibility, but also responsibility to designate areas of environmental concern and to issue or deny development permits. CAMA was also designed to recognize the fact-of-life that people expect important land use decisions to be made as near home as possible. To convey this intention, the General Assembly gave the CRC a strong local flavor by requiring 12 of its 15 members to be selected from a pool of nominees proposed by the local governments of the coastal area, and prohibited more than two members from residing outside the coastal area. In addition, the Commission's membership by law must represent prescribed coastal interests.
The Secretary of Natural Resources and Community Development was given certain functions by CAMA. Among the Secretary's more important statutory functions are proposal of interim areas of environmental concern and of implementation and enforcement criteria for local governments; making planning grants to local governments; designating three members from his department to the Advisory Council; designating the permit changeover date; processing development permit applications; issuing minor development permits in the absence of local permit programs, and initiating enforcement actions under CAMA. Additional functions are being delegated regularly by the Commission to the Secretary. The Office of Coastal Management has been established within the Secretary's office to staff the CAMA program. The head of this office serves as Executive Secretary to the CRC, and thus is the key link between the CRC and the Secretary.
Areas of Environmental Concern
Turning to the critical area, or "AEC" process, CAMA directs the CRC to identify AEC1s in two stages: interim AEC1s and permanent AEC's. The interim AEC stage has been completed and is of no current significance. The permanent designations delineate the areas that are subject to the permit requirements of the Act.
G.S. 113A-113 enumerates a series of categories that may be selected by the Commission as AEC1s. In the wording of the statute, the Commission may designate "any one or more of the following, singly or in combination":
(1) Tho categories that are particularly relevant to the North Carolina coast, "coastal wetlands" and "estuarine waters," as defined in existing statutes. (2) Three umbrella categories: renewable resource areas; fragile or historic areas and other areas containing environmental or natural resources of more than local significance; and natural hazard areas. Each of these three general categories is followed by an enumeration of subcategories that, where possible, are tied to existing North Carolina statutory procedures or that are to be identified by experts in the relevant field. One very general category that speaks in terms of legal concepts: first, the common law concept of "public trust" areas and "areas to which the public may have rights or access"; and second, a North Carolina constitutional concept--areas that the State "may be authorized to preserve, conserve, or protect under Article IV, Section 5 of the North Carolina Constitution" (the Environmental Bill of Rights). One final category of an entirely different nature: "areas which, are or may be impacted by key facilities." The term "key facilities" is defined in G.S. 11311-103(6) to include major public facilities (major airports, major highway interchanges, major frontage access roads, and major recreational facilities), and certain major private facilities (facilities for generating or transmitting energy).
The Commission adopted permanent AEC's effective July 1, 1977. These AEC1s included the two categories listed in item (1) above, and some examples of the categories listed in items (2) and (3). They did not include item (4).
In the natural hazard category only ocean hazard areas were designated. Four subcategories were included in this grouping by the CRC in its AEC guidelines: ocean beaches, frontal dunes, inlet lands, and ocean erodible areas. More specifically, these areas can be identified as follows:
--Ocean beaches extend from the Atlantic Ocean landward to a point where either the growth of vegetation or a distinct change in land form occurs.
--Frontal dunes extend from the landward side of the ocean beach to the lowest elevation in the depression immediately behind the first dune ridge. --Inlet-- lands are lands adjacent to inlets having a demonstrated tendency or probability of migrating along the Outer Banks. They have either eroded in the past 25 years or are predicted to erode based on demonstrated erosion rates.
--Ocean erodible lands have been identified by the State Geologist as hazardous to development because of excessive erosion. Based on studies of probable erosion keyed to a 25-year storm surge frequency, these lands have been identified as lying within the area that ranges landward of the toe of the frontal dune a distance of 61' (near the Virginia line) to 156' (between Cape Fear and Rich Inlets).
In the estuarine system category four subcategories were included: estuarine waters, estuarine shorelines, coastal wetlands and public trust areas. More specifically, these areas can be identified as follows:
--Estuarine waters include all of the waters and underwater lands seaward of the boundary line that demarcates the jurisdiction of the Wildlife Resources Commission (over freshwater fisheries) and the Marine Fisheries Commission (over saltwater fisheries). This covers bays, sounds, rivers and marine waters.
--Coastal wetlands include marshland that is flooded by either regular tides or occasional tides (such as wind tides). This covers both what is popularly known as "high marsh" and "low marsh"--both the marshland where spartina commonly grows and the marshland where juncus and salt meadow grass commonly grow.
--~stdrineshorelines are the areas extending 75 feet landward from mean high water level along the estuaries, sounds, bays and brackish waters. 1n-the typical marshy-estuarine shoreline this will overlap with the "coastal wetlands": only where there is more of a bank formation and no appreciable marshland will there be a discrete "estuarine shoreline." The CRCts intent in delineating an estuarine shoreline AEC was to reach areas subject to damaging erosion and flooding. --Public --trust areas include all navigable waters, all tidal waters, and the lands under these waters. In practice this subcategory extends the estuarine system AECts up the rivers that are tributary to the estuaries to the furthest reach of navigability or tidal influence.
In the renewable resource area category only two subcategories were included: small surface water supply watersheds and public water supply wellfields, The CRC actually identified four examples of these AEC classes, two in Dare County and one each in New Hanover and Pasquotank Counties. The AEC Guidelines define small surface supply watersheds as cachment areas within the coastal counties which contain a stream classified as A-11, and define water supply wellfields as areas containing well-drained sands that extend into a shallow ground water table that yields potable water.
In the fragile natural resource areas category three coastal subcategories were included: areas that sustain remnant species, complex natural areas, and unique geological formations. The CRC chose to use a special designation process in this category. Instead of itself designating all members of the class at one time, the CRC established a procedure by which a fragile area must be nominated by the local government having jurisdiction, evaluated by the CRC and then finally designated. (No fragile areas have yet been designated.)
An ---area that sustains a remnant species is one that supports native plants or animals determine2 to be rare or endangered by the Wildlife Resources Commission or the Federal government. A complex natural area is land that provides habitat for native plant and animal communities which has remained essentially unchanged by human activity. A unique geological formation is a site containing unique or especially notable geological formations or processes, or that is a unique or significant component of a coastal system.
Since March 1978 CAMA permits have been required for development within AEC's. Local permit officers (usually city or county building inspectors) issue the permits for minor developments, while the CRC1s staff issues permits for major developments. CAMA defines a "major development" as one that occupies more than 20 acres, occupies a ground area of more than 60,000 square feet, contemplates excavation of natural resources, or requires some other state environmental permit. A "minor development" is any development other than 'a major development.
Technical and Non-technical Input to Planning for Develo~mentand for Environmental Protection under CAMA
The development of AEC1s and local CAMA plans to protect environmentally critical areas and accommodate projected growth has been marked by estensive opportunities for formal public participation. It would require a large-scale investigation to identify and evaluate all of the technical and other inputs that have been fed into the CAMA planning processes. Suffice it to say, very generally, that each of the key processes--the development of the statutory AEC standards, the development of the guideline AEC and planning standards, the delineation of interim and final AECqs and the development of local land use plans--has drawn upon a variety of professional and Pay resources.
In the planning process the initial focus of attention was on developing a set of guideline criteria for classifying land into five classes (developed, transition, community, rural and conservation). Each local plan then applied these classifications to all land within the county or municipality. In order to bridge the planning and AEC processes, the planning guidelines included a section to guide local governments in correlating proposed AEC's with their land classifications. Among the professional and technical inputs to the planning process were standardized population projections, carrying capacity studies, and judgments of various biological and geological scientists identifying environmental resources that needed protection.
In the evaluation of the AEC processes a catalogue of professional and technical influence would include,- among others:
--Long established studies of fisheries and fish habitat were a basic input to the estuarine system AECqs. The well documented adverse impacts of uncontrolled development on coastal fisheries were a major force in developing public support for the enactment of CAMA and continue to be a source of support for maintaining the CAM program,
--For the ocean hazard areas a growing body of data has been collected and analyzed by geologists and other earth scientists concerning the effects of storm surges and other erosive influences. Ttae Federal flood insurance program has recently accelerated the gathering and analysis of these data. These studies have directly affected the delineation of ocean hazard AEC1s by the CRC.
--The water supply AEC1s are based directly on recommendations of state and local health authorities, based on studies and experience concerning water supply sanitation. --The language of CAMA concerning AEC1s for fragile natural resource systems was derived from studies at the N.C. State University School of Design during the 1960's for the State Planning Office.
Legislation Concerning Ocean Waste Discharges
Federal Lenislation
Modification of Secondary Treatment Requirements. Section 301 of the F.W.P.C.A., which is codified as 33 U.S.C. § 1311(b)(l)(B), requires municipal sewage treatment works to achieve secondary treatment standards. This requirement applied to all municipal treatment plants, including those discharging into the ocean, until 1977, when Congress authorized EPA to relax the secondary treatment standard. The complete text of the 1977 amendment, codified as 33 U.S.C. § 1311(h), is as follows: Mod (h) The Administrator, with the concurrence of the State, may issue a permit under section 1342 of this title which modifies the requirements of subsection (b)(l)(B) of this section with respect to the discharge of any pollutant in an existing discharge from a publicly owned treatment works into marine waters, if the applicant demonstrates to the satisfaction of the Administrator that-- there is an applicable water quality standard specific to the pollutant for which the modification is requested, which has been identified under section 1314(a)(6) of this title; such modified requirements will not interfere with the attainment or maintenance of that water quality which assures protection of public water supplies and the protection and propagation of a balanced, indigenous population of shellfish, fish and wildlife, and allows recreational activities, in and on the water; the applicant has established a system for monitoring the impact of such discharge on a representative sample of aquatic biota, to the extent practicable; such modified requirements will not result in any additional requirements on any other point or nonpoint source; all applicable pretreatment requirements for sources introducing waste into such treatment works will be enforced; to the extent practicable, the applicant has established a schedule of activities designed to eliminate the entrance of toxic pollutants from nonindustrial sources into such treatment works; (7) there will be no new or substantially increased discharges from the point source of the pollutant to which the modification applies above that volume of discharge specified in the permit; (8) any funds available to the owner of such treatment works under subchapter I1 of this chapter will be used to achieve the degree of effluent reduction required by section 1281(b) and (g)(2)(A) of this title or to carry out the requirements of this subsection. For the purposes of this subsection the phrase "the discharge of any pollutant into marine waters" refers to a discharge into deep waters of the territorial sea or the waters of the contiguous zone, or into saline estuarine waters where there is strong tidal movement and other hydrological and geological characteristics which the Administrator determines necessary to allow compliance with paragraph (2) of this subsection, and section 1251(a)(2) of this title. Three possible limitations on this authority to relax secondary treatment requirements should be noted. First, the authority is limited by its terms to an "existing discharge from a publicly owned treatment works"--i.e., to exist- ing treatment plants and outlets. Subparagraph (7) elaborates on this point by providing that there will be no new or substantially increased discharges. Second, the legislative history implies that only the West Coast, certain island possessions and territories, and Hawaii will be eligible for considera- tion of relief from the secondary treatment requirement. The Conference Committee Report on the Clean Water Act of 1977 emphasizes the importance of depth as a factor to be considered by EPA: Depth is a key factor in determining the amount of circulation in waters of the territorial sea or contiguous zone. Circulation in turn affects the degree to which waste water discharges to these waters are rapidly dispersed. In some instances, depth of water in the territorial seas or contiguous zone in excess of 200 feet is necessary to achieve sufficient- ly rapid dispersion (i.e., 45 seconds) of waste water and waste water constituents. In some instances, depths of 200 feet is insufficient to provide adequate dispersion. Poor net flushing (i.e., stagnation) of a deep basin may cause undesirable vertical cycling of dischargesl. The Report goes on to say: Areas described by these conditions include most of the coast of the western United States, the coasts of Hawaii, Puerto Rico, American Samoa, the Virgin Islands, and portions of estuarine waters such as Cook Inlet near Anchorage, Alaska, and Resurrection Bay near Seward, Alaska. * Factors other than depth may appropriately be considered, however, as the Conference Report indicates in the following excerpts: Factors determining the amount and rapidity of dispersion of saline estuarine waters are the degree of tidal movement and other hydrological and geological characteristics. In some cases, rip currents and strong tidal movements which contribute to high flushing efficiency in certain bays and estuaries, may provide sufficient circulation. Additional precautions, however, need to be considered in or near the mouths of estuaries due to possible tidal transport of pollutants landward into 'estuarine areas where they may be retained. Distance offshore for location of outfall lines is also a factor which must be considered in many situations. In these cases, sufficient distance offshore is generally necessary so that adverse water quality conditions will not be created under assumed worst conditions of onshore current and wind based on data derived from historical records. Greater distance offshore may provide the desired protection during adverse conditions of onshore currents and wind. Geological characteristics such as submarine canyons may also be utilized because of the same advantages of rapid dispersion and desirable cir~ulation.~ Third, there is a statutory deadline on the filing of applications for relief from the secondary treatment requirement. Paragraph (j)(l)(A) of Section 301, codified as 33 U.S.C. 5 1311(j)(l)(A), provides that any application for a modification of the secondary treatment requirements "under subsection (h) of this section shall be filed not later than 270 days after the date of enactment of the Clean Water Act of 1977." Since the Clean Water Act was enacted on December 30, 1977, this filing deadline was September 24, 1978 (or September 25, since the 24th was a Sunday). The subsequent administrative interpretation of the 1977 Act elaborates on the depth and locational factors, the existing discharge limitation, and the filing deadline. EPA has adopted final regulations concerning all of these subjects, Depth and tocation, In its proposed regulations EPA came quite close to precluding consideration of Atlantic Coast or Gulf Coast outfall locations and to mandating a minimum ocean depth of 200 feet at the point of di~char~e.4 The final regulations, however, retreated from these views; if anything, they diluted the adverse inferences that might be drawn from the legislative his- tory with respect to primary treatment for Atlantic and Gulf Coast outfalls. The regulations themselves do not speak to these matters, and the explanatory comments expressly reject both limiting depths and limiting geological or hy- drological conditions. As to the former, the comments state that, "there is not evidence that Congress had a specific minimum depth limitation in mind."5 Existing Discharges. The proposed regulations state that the statutory reference to "existing discharges" means discharges "actually flowing into marine maters on or prior to December 27, 1977,"the effective date of the 1977 Act. As adopted, the final regulations relaxed this definition somewhat to cover not only the "current discharge" (as of any time between December 27, 1977 and 3 months after the date of publication, as designated by the applicant), but also a thoroughly planned and studied proposal for an outfall or treatment system (an "improved dischargew).7 This change from the proposed regulations opens up the list of potential applicants to some that would have been ineligible under the proposed regulations. But any applicant still must overcome a prohibition against issuing permits "where the applicant's discharge was not actually flowing into ocean waters or saline estaurine waters as of December 27, 1977.~8 The Filing Deadline. The final regulations made it plain that EPA takes seriously the statutory deadline for filing applications to allow primary treatment for ocean outfalls, but slightly relaxed the actual deadline. Under the regulations a preliminary application must have been submitted by September 25, 1978 and a final application by September 13, 1979 (three months after the adoption of the regulations).9 If North Carolina coastal communities have not already filed applications, they apparently are ineligible for Section 301(h) relief, unless the statute is amended or EPA waives the deadline. Neither the regulations nor accompanying comments give any encouragement to a waiver of the deadlines. In summary, it appears in light of the legislative history and EPA's interpretive regulations that: (1) Atlantic and Gulf Coast outfalls with primary treatment will not be ruled out because of depth or location factors; (2) the "existing discharge" limitation should not eliminate any North Carolina location, assuming there was an ocean or saline estuarine discharge of some kind for the location as of December 27, 1977; but (3) the statutory filing deadlines will present problems unless timely applications have already been filed for North Carolina outfalls with primary treatment. Ocean Discharge Criteria. The legal. picture is complicated by an additional section, 5 403 of the F.W.P.C.A., covering much the same ground as 5 301 in similar but not identical terms. 5 403, codified as 33 U.S.C. 5 1343, prohibits the issuance of an NPDES permit for discharge into the territorial sea, the waters of the contiguous zone, or the ocean except in compliance with guidelines developed by the EPA Administrator. It then provides as follows: Guidelines for determining degradation of waters (1) The admininistrator shall, within one hundred and eighty days after October 18, 1972 (and from time to time thereafter), promulgate guidelines for determining the degradation of the waters of the territorial seas, the contiguous zone, and the oceans, which shall include: (A) the effect of disposal of pollutants on human health or welfare, including but not limited to plankton, fish, shellfish, wildlife, shorelines, and beaches; (B) the effect of disposal of pollutants on marine life including the transfer, concentration, and dispersal of pollutants or their by-products through biological, physical, and chemical processes; changes in marine ecosystem diversity, productivity, and stability; and species and community population changes; (C) the effect of disposal of pollutants on esthetic, recreation, and economic values ; (D) the persistence and permanence of the effects of disposal of pollutants; (E) the effect of the disposal at varying rates, of particular volumes and concentrations bf pollutants; (F) other possible locations and methods of disposal or recycling of pollutants including land-based alternatives; and (G) the effect on alternative uses of the oceans, such as mineral exploitation and scientific study. In any event where insufficient information exists on any proposed discharge to make a reasonable judgment on any of the guidelines established pursuant to this subsection no permit shall be issued under section 1342 of this title. When EPA failed to adopt guidelines within the time frame set by § 403(c), the Pacific Legal Foundation brought suit to compel EPA to act. This suit was successful. The District Court for the Eastern District of California in October 1979 issued an order establishing a schedule requiring EPA to adopt interim guidelines by November 9, 1979 and final guidelines by July 30, 1980. Pacific Legal Foundation v. Costle, 10 E.L.R. 20140 (E.D. Calif., 1979). Proposed guidelines were published in the Federal Register on February 12, 1980 and final guidelines were published in the Register October 3, 1980, to become effective November 3, 1980.10 The final guidelines take into consideration the similarity of the 5 301(h) and § 403 requirements by providing that discharges in compliance with 5 301(h) "shall be presumed not to cause unreasonable degradation of the marine environment."ll The same presumption is accorded to discharges in compliance with variances or state water quality permits. In its comments on this provision, EPA stated that it created a "rebuttable presumption" that a § 301(h) approval will satisfy § 403(c) guidelines also. By way of elaboration, EPA added that, while a permit writer might drawn upon § 403(c) to justify additional conditions in a 5 301(h) permit, it is unlikely that this will be necessary.12 Ocean Dumping. In 1977 Congress amended the Ocean Dumping Law by directing the Administrator of EPA to: end the dumping of sewage sluge into ocean waters . . , as soon as possible after the date of enactment of this section, but in no case may the Administrator issue any permit, or any renewal thereof (under Title I of the Marine Protection, Research, and Sanctuaries Act of 1972) which authorizes any such dumping after December 31, 1981. [33 U.S.C. § 1412a(a).] The language as written appears to give EPA some leeway in determining whether a particular dumping activity will "unreasonably degrade or endanger" the marine environment, human health, economic potentialities, etc. Some of the legislative history confirms that EPA could grant an extension of dumping beyond the 1981 deadline after finding that a sludge discharge would not unrea'sonably endanger or degrade human health or the environment. l3 The permit referred to in 33 U.S.C. 5 1412a(a) above is authorized by the original Ocean Dumping Law of 1972, 33 U.S.C. § 1412, which empowers EPA to issue permits for dumping sewage sludge or industrial wastes into the territorial seas or the contiguous waters, upon making the same finding that is set forth in § 1412a. A related section, 33 U.C.S. § 1413, authorizes the Army Corps of Engineers to issue permits for ocean dumping of dredged material, subject to EPA veto. During the interval between the original enactment of the Ocean Dumping Law in 1972 and the adoption of the 1977 amendment, EPA developed an interim permit system for ocean sludge dumping.14 The final revised permit regulations imposed a December 31, 1981 cutoff date on continued availability of interim permits allowing disposal of wastes that exceed established criteria. EPA has used this authority in its efforts to bring sludge-dumping on the east coast under control, Reportedly two of the three major sludge dumpers on the east coast, Camden, N.J. and Philadelphia, have accepted permits expiring by 1980; only the New York-New Jersey metropolitan area remains to be brought under the deadline.15 EPA also won a legal victory on the west coast by obtaining federal district court approval of its order directing the City of Los Angeles to cease discharging sewage sludge through an outfall beyond the three-mile limit, in Pacific Legal Foundation v. Quarles.lG The court ruled that EPA1s order was justified by a combTnation of the requirement of FWPCA 5 301's requirement for secondary treatment of municipal sewage and the general policy of the Ocean Dumping Act for phasing out ocean discharges. In light of this history, there remain some unanswered questions concerning the nature and extent of EPA's discretion under the 1981 statutory deadline on ocean sludge dumping. Did the statutory deadline merely embody the status quo of interim administrative permits, nominally terminating in 1981, but in fact subject to further administrative extensions? Or did the statutory deadline legislatively terminate all interim administrative permits at the end of 1981, as some House proponents of the legislation believed?l7 How are these issues affected by factors bearing on the economics as well as the ecology of alternative sludge disposal methods? The Environmenal Law Reporter commented as follows on these issues: The recent amendment to the Ocean Dumping Act may be viewed as setting a 1981 cut-off for the ocean disposal of sewage sludge that might harm the marine environment, which means essentially all the sludge now being produced by municipal treatment plants. On the other hand, the measure could be interpreted as allowing the dumping of potentially harmful sludge beyond the deadline provided such dumping is "reasonable" in view of the lack of economically or environmentally feasible alternatives. It is too early to tell which interpretation EPA, the most important player in the ocean dumping game, will choose to adopt. But it may be that Congress' latest action regarding ocean dumping raises more questions than it resolves. l8 'North Carolina Legislation G.S. 143-214.2(c) provides as followsp: The discharge of wastes, including thermal discharges, to the open waters of the Atlantic Ocean over which the State has jurisdiction are prohibited, except where such discharges are permitted pursuant to regulation duly adopted by The Environmental Management Commission. Since State regulations follow Federal law and regulations concerning NPDES permits, it appears that the Environmental Management Commission is authorized to issue permits allowing municipalities to make whatever ocean discharges are authorized by Federal law and regulations. The so-called "Hardison Amendment," G.S. 143-215(c), probably ensures that no EMC requirements will be adopted that are stricter than the EPA regulations. The text of G.S. 143-215(c) reads as follows: (c) In adopting effluent standards and limitations the Environmental Management Commission shall be guided by the same considerations and criteria set forth, from time to time, in federal law for the guidance of federal agencies administering the Federal Water Pollution Control Program. It is the intent of the General Assembly that the effluent standards and limitations adopted hereunder shall be no more restrictive than the most nearly applicable federal effluent standards and limitations. Conclusions (1) Federal law generally requires that all municipal sewage treatment plants provide a minimum of secondary treatment, whether the wastes are discharged onshore or offshore. § 301(h) of the 1977 Clean Water Act authorizes EPA to relax this standard under certain conditions and allow primary treatment for ocean outfalls, as well as for some estuarine outfalls. Under EPA regulations interpreting this section, ocean outfall with primary treatment in North Carolina has the potential to qualify for EPA approval if: (a) There was an ocean or saline estuarine discharge of some kind for the location as of December 27, 1977; and (b) A timely application for approval of primary.treatment for the location has already been filed. (2) Section 403 of the 1977 Clean Water Act, concerning ocean discharge criteria for NPDES permits, covers much the same ground as 5 301(h). EPA's guidelines for 5 403 would rebuttably presume that a 5 301(h) waiver of the secondary treatment requirement meets the guidelines for § 403. (3) In 1977 Congress enacted a 1981 statutory deadline on ocean dumping of sewage sludge. EPA retains some discretion to allow further sludge dumping after 1981, however, because the law prohibits only dumping of wastes that may "unreasonably degreade or endanger human health, welfare, activities, or the marine environment, ecological systems, or economic potentialities." If any sludge dumping off North Carolina shores is anticipated, this legislation apparently does not pose an absolute barrier. (4) North Carolina legislation essentially follows federal law and regulations in these respects, FOOTNOTES 1. Conference Committee Report on Pub. L. 95-217, 1977 U.S. Code Cong. and Admin. News, p. 4449. 2. -Id., at p. 4450. 3. -Id., at p. 4450. 4. Fed. Reg., Vol. 43, p. 17487, 17494. April 25, 1978. 5. Fed. Reg., Vol 44, p. 34802. June 15, 1979. 6. Fed. Reg., Vol 43, p. 17494. April 25, 1978. 7. 40 C.F.R. 5 125.59(a). Fed. Reg., Vol. 44, pp. 34788-90, 34817, June 15, 1979. 8. 40 C.F.R. 5 125.59(b)(3). Fed. Reg., Vol. 44, p. 34817, June 15, 1979. 9. 40 C.F.R. § 125.59(c) and (d)(2). Fed. Reg., Vol. 44, p. 34790-91, June 15, 1979. 10. Fed. Reg., Vol. 45, pp. 9548, 65942. Feb. 12 and Oct. 3, 1980. 11. Fed. Reg., Vol. 45, p. 65954; 40 C.F.R. 5 125.122(b). Oct. 3, 1980. 12. Fed. Reg., Vol. 45, p. 65951. Oct. 3, 1980. 13. 123 Cong. Rec. S 17420. (Response by Senator Muskie to question from Senator Moynihan in Senate floor debate.) 14. Fed. Reg., Vol. 38, p. 28610 (Oct. 15, 1973); 40 C.F.R. 51 220-229 (Jan. 11, 1977). 15. E.L.R. 10226, 10227, "Ocean Dumping Revisited: New Statutory Deadline May not Stop Sea Disposal of Sewage Sludge." 16. 440F. Supp. 316(C.D. Calif., 1977). 17. 123 Cong. Rec. H 11022-23 (Oct. 14, 1977). 18. 7 E.L.R. 10226, 10229. Chapter VI CONCLUSIONS Population in the coastal areas of North Carolina is growing and is expected to continue to grow in the foreseeable future. Pressures for development of the rich recreational and tourism resources of coastal North Carolina are moving south from the population centers of the northeast. Pollution of groundwater and inland coastal waters are among the many threats to the fragile coastal environment that can be expected from such development. Pollution of the groundwater endangers water supplies, particularly on the barrier islands, while pollution of the inland coastal waters has already resulted in the closing of once-profitable shellfish growing areas and threatens to close more. Continuation of the present methods for managing wastewaters, generally by septic tanks and drainage fields on the barrier islands and by discharge of often inadequately-treated wastewaters from mainland communities into inland coastal waters, is having and will continue to have serious deleterious impacts on the water resources in the area. Septic tanks are unsuitable because even when operating properly, they foul underground waters and pollute the inland waters into which they inevitably drain. And a high percentage do not operate properly. For the densely populated areas of the coastal North Carolina, only sewerage can promise relief from continued despoilation of the aquatic environment. Two somewhat different areas of coastal North Carolina were selected for study: Dare County in the north and Carteret County (including part of Onslow County) in the south. They characterize coastal North Carolina in that they include barrier islands and mainland separated by inland coastal waters and they are sparsely populated, with no major urban centers. They are both important recreational areas, particularly for summer tourists and residents, and both have supported shellfish harvesting. Three methods of disposing of collected wastewaters are examined in this study: 1) Treatment and disposal to inland coastal waters; 2) Treatment and disposal on land; and 3) Treatment and disposal through a long outfall into the ocean. The type and degree of treatment selected are intended to meet the water quality standards oE the receiving waters and to protect the public health, Reuse of wastewaters is an option that is attractive where water supplies are limited. It is not considered in this report because the study indicates that water resources for water supply are ample in both study areas for the foreseeable future. Shellfish growing areas, particularly those for clams and oysters, are limited in extent and extremely vulnerable to pollution because they are filter feeders and concentrate contaminants to which they are exposed. Furthermore, because clams and oysters are eaten raw, they constitute a serious threat to public health, Many shellifish beds have already been closed for commercial exploitation because of pollution from septic tank drainage and wastewater discharges. Not only have such closings had a severe impact on the fisheries industry in North Carolina, and on the availability and cost of shellfish to the public, but the threat to health continues to exist because many shellfish are harvested and distributed outside traditional commercial channels. Clams and oysters ingest vast amounts of waters and concentrate particulates including bacteria and viruses far in excess of concentrations in the aquatic environment in which they grow. Even when the water meets the bacteriological standards for shellfish growing, 70 coliform per 100 ml, the shellfish must be considered suspect where wastewaters find their way into the growing areas. Viruses, particularly those that are responsible for infectious hepatitis are troublesome because standards have not yet been established for them. Viruses in general are difficult, and infectious hepatitis impossible, to assay. Shellfish constitute today a most important vehicle for the transmission of infectious hapatitis. Inland coastal waters that support shellfish suffer from poor circulation. The flushing and movement that may make wastewater discharges to rivers, estuaries and ocean acceptable are often not available in coastal backwaters. Accordingly, although discharge to inland waters is evaluated in this study, only two approaches to wastewater disposal are considered to be environmentally acceptable for the coastal areas of North Carolina: ocean disposal and land disposal. Land disposal, while not well adapted to the barrier islands because of limited land areas available and because of the unsuitability of the soil, may be the solution of choice for coastal mainland communities. Ocean disposal is the most environmentally acceptable solution for wastewater disposal for the barrier islands. The major problem with ocean disposal is the need for extensive sewerage to collect the wastewaters at a single point for disposal, Long ocean outfalls exhibit strong economies of scale, and if an ocean outfall is to be used for scattered populations such as in coastal NC, large areas need to be brought together, requiring extensive interceptors and numerous pumping stations, Also, because of the relatively shallow continental shelf off North Carolina, outfalls need to be quite long. This report summarizes the evaluation of a wide variety of options for the design of sewerage collection and wastewater treatment systems in combination with those methods of disposal to inland coastal waters, to land, and to the ocean. Ocean Out falls Public Law 92-500, enacted in 1972, calls for a minimum of secondary treatment, even for wastewaters to be discharged to the ocean. As it became evident that secondary treatment in such situations is often wasteful of both funds and energy, pressure from West Coast communities resulted in the inclusion in the Clean Water Act of 1977, PI, 95-217, of a waiver under certain circumstances, most of which are applicable to the West Coast. Continued concern for the wastefulness of secondary treatment prior to ocean discharge resulted in the adoption by EPA, on ,June 8, 1979, of revised regulations that allowed primary treatment under certain prescribed conditions, such as ensured adequacy of water quality protection, a suitable monitoring program and provision of necessary pretreatment. Accordingly, four options for ocean disposal are evaluated in this study: primary treatment, with and without chlorination; and secondary treatment, with and without chlorination. As indicated in Table 2-7 for the Northern area and Table 3-6 for the Southern area, the least cost option that provides adequate beach protection in both areas is primary treatment plus chlorination. Inasmuch as secondary treatment without chlorination requires the same length of outfall, an economical solution would be to provide the required length of outfall for primary treatment and chlorination (which is the same length as for secondary treatment without chlorination), while allowing space at the treatment plant site for possible expansion to secondary treatment. If monitoring of the ocean in the vicinity reveals that secondary treatment is, in fact, necessary, it can be added. Chlorinatfon of the effluent can then be abandoned without significant loss as capital costs for chlorination facilities are small. However, experience with ocean discharge indicates that primary treatment would be adequate. Evaluation of the Options Had the combination of extensive sewerage, treatment and long outfalls into the ocean resulted in substantially higher costs than required for disposal of wastewaters to the inland coastal waters, conclusions and recommendations for wastewater management in the coastal areas would have been difficult to reach, How much additional investment is warranted to avoid wastewater discharges to the fragile inland coastal waters? Even if appropriate treatment is provided prior to discharges to the inland waters, is there assurance that these facilities would be operated properly and, even if operated properly, that they would indeed protect the shellfish? The questions are moot, as the findings of this study indicate that solutions that do not involve discharges to the inland waters, i.e. solutions that call for either ocean or land disposal, or a combination of the two, are no more costly, and in fact are generally less costly, than the environmentally questionable solution involving discharge to inland coastal waters. Because of the very preliminary nature of the designs upon which the cost estimates are based, and the many assumptions that are required in a study such as this, the cost estimates are inexact. Cost functions were necessarily drawn from experiences elsewhere, as ocean outfalls have not yet been built in North Carolina. Also, precise estimates for sewers and outfalls depend upon field exploration as such costs are extremely sensitive to specific site conditions that govern ease of construction. Thus the cost estimates are not considered sufficiently precise to permit proceeding with implementation of any specific solution. Nevertheless, the cost estimates are considered adequate for purposes of comparing various options in the same area. The greatest uncertainties involve the selection of required outfall lengths to protect the bathing beaches. Assumptions made for inshore currents and bacterial dieaway are extremely conservative and detailed study is likely to indicate that outfall costs can be relatively lower than those found in this report. The following sections summarize the findings of the evaluation of the various options in the two study areas. Northern Area Some 25 options were considered in the Dare County area, based upon serving the Kill Devil Hills, Nags Head and Whalebone Junction communities on the barrier island and Manteo and Wanchese on Roanoke Island. Table 6-1 summarizes the results. The study reveals that options that involve ocean disposal are among the least costly while those that involve discharge to the inland coastal waters are among the most costly. The reasons for this are indicated in Table 6-2 in the comparison of typical options involving disposal of wastewaters entirely to inland coastal waters, to the land or to the ocean. Plans that involve discharge to inland coastal waters are costly because they involve both costly treatment and costly interceptors to reach disposal sites that are acceptable. Land disposal costs reflect the high cost of distribution of wastewater on the land, an indicated in Table 2-13. Even the income from crops are not adequate to offset these costs. The least cost ocean disposal option, as shown in Table 2-7, involves primary treatment plus chlorination, with a single 2.1 mile outfall. The recommended option for the Northern Area is ocean disposal for all the communities to be sewered on the barrier islands and on Roanoke Island as illustrated on Map 2-6. Southern Area A total of 60 options for sewerage, treatment and disposal were evaluated in the Carteret County-Swansboro area to serve Bogue Banks, Beaufort, Morehead City, Newport and their townships, Cape Carteret and Swansboro. Table 6-3 and 6-4 summarize the results. Table 6-1. Summary of Dare County Wastewater Disposal Options Number of Range of Total Costsx Points of Discharge Options ($ millions) Coastal Waters Only 14 35 - 40 Land Disposal Only 4 34 - 37 Ocean Disposal only*** I 28 Wetlands only 1 ---* * Coastal Waters and ocean*** 4 30 - 31 Land and ocean*** 1 28 Number of options 2 5 - * Includes capital costs and the present value of operation and maintenance, based on 6% and 20-year life. ** Costs were found to be excessive, so are not assessed in detail. *** Ocean disposal option shown is the lowest cost of four options with regard to length of outfall and degree of treatment, namely primary treatment and chlorination. Table 6-2. Comparison of Dare County Options Plan costs* ($ millions) No. Discharge Interceptors Treatment Disposal Total CW (3 outfalls) 2 1 CW (1 outfall) 23 Land (1 site) 2 2 Land (2 sites) 18 Ocean (Primary Trtmnt, 6 20 Chlor. ) Ocean ( Secondary Trtmnt .) 20 Includes capital costs and the --present value of operation and maintenance costs. The study reveals that the lowest cost options include all three methods of disposal--to inland coastal waters, to the ocean and to the land. Despite the extent of the area to be served, ocean disposal for the entire area is in the range of lowest cost. Disposal entirely to coastal waters or entirely to land are substantially more costly because of the high cost of treatment required for the coastal water discharge and the relatively high cost of land application for land disposal. The least cost configuration is that which calls for ocean disposal of wastewaters from Bogue Banks and Morehead City, with land disposal for the other areas. This is illustrated on Map 3-7. As shown in Table 3-15, a wide range of other options involving a combination of ocean and land disposal show costs of the same order of magnitude. Because land disposal requires less regional cooperation, any one of these other low-cost options may be as readily implemented as the least-cost plan. Several low cost options involve discharge to inland coastal waters. However, because these are far less attractive from an environmental and health standpoint, and because they show no cost advantage, they are not recommended for consideration. Suggested Institutional Arrangements The key factors in determining organizational arrangements in both areas are financial capacity, jurisdictional adequacy, political feasibility, managerial capability, and existing arrangements. Most of the existing community wastewater systems are small and have limited financial capacity. Moreover, the recommended disposal systems combine the discharges from several different communities. In the Northern Area, given these conditions and the fact that Dare County already has a countywide water system in place, the financing and management of all wastewater disposal facilities by the County is recommended. In the Southern Area, Carteret County management appears to be the most desirable approach, especially for the Bogue Banks facilities, The principal mainland municipalities in the Southern Area are somewhat larger than those in the Northern Area and operate existing wastewater systems. For these reasons, division of management responsibilities is feasible in the Southern Area should countywide management prove unattainable. The use of a county service district covering at least the Bogue Banks area merits consideration if local taxation on less than a countywide basis is found necessary. Legal Considerations Federal and State legislation set the legal ground rules for water management in coastal North Carolina. Federal law is especially important for land treatment of wastewaters and for ocean discharges; North Carolina law, for septic tanks and land use management. Table 6-3. Summary of Carteret County Area Wastewater Disposal Options Number of Range of Total costs* points of Discharge Options ($ millions) Coastal Waters Only 2 43 - 48 Land Disposal Only 6 43 - 47 Ocean Disposal only** 1 3 9 Coastal Waters and Land 36 39 - 52 Land and ocean** 15 38 - 42 Numbers of Options 60 Includes capital costs and the present value of O&M costs, based on 6% and 20-year life. ** Ocean disposal option show is the lowest cost of four options with regard to length of outfall and degree of treatment namely primary treatment and disinfection. Table 6-4. Comparison of Carteret County Options Plan costs* ($ millions) No. Discharge Interceptors Treatment Disposal Total Coastal Waters (2 outf alls) Land (3 sites) Ocean (Primary & Trtmt. Chlor. Ocean (Secondary Treatment) Land and Ocean (Prim. & Chlor.) Bogue Banks and Morehead City to ocean outfall Land and Ocean (Prim. & Chlor.) Bogue Banks and Morehead City & Beaufort to ocean outfall Land and Ocean (Prim. & Chlor.) Bogue Banks, Morehead City, Beaufort-Newport to ocean outfall * Includes capital costs and present value of O&M costs. Federal law strongly encourages land treatment of wastewaters as a preferred way of achieving national clean water goals. Under the Clean Water Act of 1977 "alternative waste management techniques," including land treatment, must be evaluated before federal sewage treatment grants can be made. North Carolina may or may not be able to secure E.P.A. approval for an ocean outfall program with no greater than primary treatment. Although federal law generally requires that all municipal sewage treatment plants provide a minimum of secondary treatment, the 1977 Act authorized E.P.A. to relax this standard and allow primary treatment under certain conditions for ocean outfalls discharging into deep waters. It is an open question whether this relaxing of secondary treatment standard is available in North Carolina waters. North Carolina law makes septic tanks a legally acceptable option for wastewater treatment in many coastal settings, subject to some conditions and restrictions. A combination of state health regulations, state environmental regulations and local health ordinances must be examined in order to identify the appropriate procedures, to predict whether approval will probably be forthcoming for a septic tank, and to determine what standards will govern the siting, design and installation of the system. The North Carolina Coastal Area Management Act (CAMA) lays the foundation for cooperative state-local planning and regulation of land development along the state's estuaries and ocean beaches, and in other areas of legitimate public concern, such as public water supply watersheds, The presence of the CAMA program provides a setting for orderly land development and reduces the temptation to use water supply and wastewater services as a surrogate form of land use control. Public water supply sources can be protected under a number of different North Carolina statutes. By way of illustration these include capacity use area designation; area of environmental concern designation under CAMA; denial or conditioning of well construction permits, waste discharge permits or public water supply approvals; and denial or conditioning of permits for disposal of wastes so close to water supply intakes as to adversely affect a public water supply. 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