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Title 7 Natural Resources and Environmental Control

7100 Groundwater Discharges Section

7103 Guidance and Regulations Governing the Land Treatment of Wastes

August, 1988

Amended, June, 1994

Amended, October, 1999

Foreword

Statewide regulations governing the land treatment of wastes have existed since 1974. The State's efforts to improve water quality through the collection and centralized treatment of wastewaters have resulted in the rehabilitation of existing treatment works and the construction of new facilities. These facilities generally utilize biological processes to treat the wastewaters from residences, commercial establishments, and industry. In addition to providing the required treatment, sludges are generated. This residual material is a slurry of water and solids that can be 100 times more concentrated than untreated wastewater. Inadequate treatment of sludge and poor operation and maintenance practices have resulted in the contamination of the state's groundwaters and presented a threat to the public health, safety and welfare.

Animal manures tonnage in the range of 600-800 thousand are produced annually in the State. Enough manure is produced to supply all the nitrogen for all the corn grown in Delaware. Over application, improper storage and timing of manure applications have contributed to contamination of both surface and groundwaters in the State. When properly managed, animal manures can provide substantial benefits to the agricultural community with minimal impacts on public health, safety, and welfare.

The purpose of this document is to prevent the problems listed above. The guidance and regulations are based upon the best information available. They provide the waste management actions necessary to achieve U.S. Environmental Protection Agency Drinking Water Standards on an average annual basis. This conforms with the State policy which was recommended to the Department and adopted from the 1983 Final Report of the Comprehensive Water Resources Management Committee.

All options for use and disposal of these waste materials have costs, benefits, and risks. The Department believes that guidance and regulations are the best way to promote good practices for utilization and disposal that minimize the potential adverse impacts on public health and the environment and maximize the potential benefits. The benefits potentially gained through waste utilization include energy and nutrient recovery, soil improvement, and the conservation of valuable natural resources.


1.0 Introduction

1.1 The attainment of water quality goals in the face of economic uncertainties, reduced government subsidies, and rising construction costs imposes a heavy responsibility on public officials, industrial personnel, and consulting engineers. It is not enough to provide facilities that will meet effluent and ambient water quality standards; a rigorous search for least-cost solutions to water quality problems is also needed. Project designs should minimize capital and operational costs when compared to other alternatives for the entire life of the project.

1.2 Land treatment of wastewaters, sludges and other residual wastes is a proven and cost-effective alternative to traditional technology over a wide range of circumstances where the necessary land is available at reasonable cost. For effluents and sludges, it is particularly attractive at locations where the design flow of receiving waters is low, waste treatment requirements are high and suitability of landfills is low. The full advantages of land treatment will not be realized, however, unless there is a concerted effort to focus the designs on essential features. Groundwater quality and public health must be protected, but treatment hardware and operational criteria should be based on firm evidence of need. Lined earthen lagoons should be used whenever possible and concrete, steel, and firm-set structures limited except where fully justified. All persons involved in the planning, review, and supervisory processes should take steps to assure that these objectives are realized.

1.3 The general guidelines associated with this document provide a sound technical basis for the design of land treatment systems. These systems encompass new opportunities for wastewater conservation, utilization of sludge, and the support of improved stewardship of land and water resources. Land treatment offers important cost-effective alternatives for wastewater management.

2.0 Program Scope

Wastewater and sludge generators are often forced to use only conventional waste treatment and disposal technology because of difficulties in understanding policies and procedures for the evaluation and approval of land treatment systems. The program presented in this document and the series of general technical guidelines provide assistance with policies and procedures, regulatory requirements, advisory services, design procedures and technical evaluation of land treatment systems.

General technical guidelines have been developed for the following three categories of land treatment systems:

1. Land Treatment of Wastewater;

2. Land Treatment of Sludge and Sludge Products; and,

3. Land Treatment of Agricultural Residuals.

These three topics have been selected because of existing technical knowledge, regulatory requirements, and perception that a need exists for a better public understanding of these waste treatment categories. Municipal or sewage sludges and wastewaters are given substantial attention in the documents; however the modifications to address industrial wastewaters and sludges are also included.

3.0 Statement of Regulatory Objectives for Land Treatment in Delaware

A general statement of purpose is to protect and improve environmental quality in Delaware by providing further treatment and recycling of wastes. The objectives are:


• To regulate and manage land treatment of wastewater and sludge.

• To assure long-term land productivity, such that no land is irreversibly removed from significant potential agricultural land use.

• To protect groundwater quality and assure that drinking water quality standards are met.

• To safeguard public health within reasonable standards.

• To improve the regulatory climate for land application ofwastes, public understanding, and implementation of current and evolving technology by municipalities and industries.

Specific objectives in using land treatment technology are:



• To establish criteria for the application of wastes to the plant-soil system at such rates or over such limited time span that no land is irreversibly removed from some other potential societal usage (agriculture, development, forestation, etc.).

• To establish a methodology for the intimate mixing or dispersion of wastes into the upper zone of the plant-soil system with the objective of microbial stabilization, immobilization, selective dispersion, or crop recovery leading to an environmentally acceptable assimilation of the waste.

• To promote effective regulation, public understanding, and implementation of current and evolving technologies by governmental units and industries in the State.

• To establish reasonable measures of protection for the environment and public health, safety, and welfare by providing for the proper design, operation, and management of land treatment systems; and the proper treatment, transport, handling, and beneficial use of wastes.

• To require the use of plant-soil and waste management practices and technology that will function according to the performance criteria without causing the State's groundwater resources to violate duly promulgated drinking water standards on an average annual basis.

• To dispose of non-hazardous sludges in landfills is an inefficient use of resources. Pretreatment programs and sludge management programs should be directed to provide adequate treatment for land application.


4.0 Public Acceptance

4.1 The importance of a comprehensive and well-coordinated public acceptance program for the implementation of land treatment systems may be described by the old adage, "an ounce of prevention is worth a pound of cure." Good documentation exists for many fine land treatment systems which have operated successfully for many years. Yet, public resistance may develop when new systems are proposed for individual communities unless preparatory steps are taken.

4.2 The public education and acceptance program should be one of the first activities in the process to implement a land treatment system. Citizens should be encouraged to weigh the relative capabilities, advantages and disadvantages, and costs of alternative solutions. An educational program to assist in the collection and presentation of this information is a vital part of the public acceptance activity. Relevant information and participation may be obtained locally from citizens with high interest or appropriate expertise; technical institutes and university personnel; local representatives from agencies such as the Cooperative Extension Service, Soil Conservation Service, and Soil Conservation Districts, as well as supportive state staff for these agencies; local government planning agencies; and appropriate environmental organizations. Involvement of such resources and agency representatives can serve to coordinate and expand the program reach to involve all interested groups and concerned citizens.

4.3 Four major sectors of the public should receive particular attention in the public acceptance program:

4.4 The land owners or farmers who are to receive the waste, their neighbors, public interest groups, and the broader range of citizens who must provide the resources and assume ultimate responsibility for decision-making. The farmers may be unfamiliar with the effects of wastes on crop production and land value. They need to be informed of the economic and environmental benefits of land treatment and the essential soundness of the practice.

4.5 Their neighbors, public interest groups, and other community citizens may be sensitive about "dumping" urban wastes in their neighborhood and have concerns about odor, health problems, and groundwater pollution. Finally the citizens in a broader area are concerned that adequate design, appropriate legal compliance, and a blend of fiscal responsibility and environmental protection are achieved.

4.6 Many benefits result when the public acceptance program is planned and conducted by involved citizens. Such local leadership will facilitate consideration of issues perceived by involved individuals to be most important and the utilization of resource agencies, people, and printed material of highest relevance and interest. The public acceptance program should be conducted in close cooperation with or under the supervision of the overall land treatment project.

4.7 Educational activities and materials that may be helpful for the public acceptance program include: Individual presentations and open discussions, assembly and review of appropriate written material, slide and movie presentations, seminars by recognized state and national leaders, and trips to similar sites in both the state and region. Workshops should be held to encourage the evaluation of alternative possibilities on a technical, cost, environmental, and social basis. Good media relationships, assistance of respected experts, and test plot demonstrations may also be important components of a comprehensive public acceptance program.

4.8 The purpose of the public acceptance program is to assist involved citizens in making an unemotional, informed, and objective evaluation of alternatives available to solve a clearly defined need or problem. Program components should provide an opportunity for every person who desires to be involved to receive desired information, upgrade their understanding of alternatives, and personally become part of the planning and evaluation process. The end goal is to develop recommendations that will encourage the best possible final decision.

5.0 Delaware Statutes and Regulations

The construction and operation of waste collection, treatment, and disposal systems and facilities discussed within this document are regulated by the Department of Natural Resources and Environmental Control. The Delaware Environmental Protection Act requires that a valid permit shall be obtained for collection, treatment, and disposal of waste. This statute grants authority to the Department to develop rules and regulations to carry out its regulatory duties.

5.1 The Regulations specify minimum requirements needed to protect the public health and environmental quality. The technical guidelines provide guidance on system planning and design.

5.2 Several other agencies are involved with waste management in Delaware. Inquiries should be made to assure compliance with all applicable requirements. Information about additional requirements which might apply may be obtained from the Department, Delaware Division of Public Health, county planning and zoning agencies, and the advisory groups listed in a later section of this document.

6.0 Administrative Permitting Procedures and Requirements

The administrative permitting procedures for land treatment systems vary depending on the type of permit required. The rules of practice contain the requirements for the respective permitting procedures. Municipal wastewaters and sludges are regulated herein, but specific deviations are noted when wastewaters and sludges are directly from an industry. A brief description of the relevant administrative process are listed below for each type of facility:

6.1 Land Treatment of Wastewater

A State Permit is required for the construction and operation of these facilities. The completed application package must be submitted to the Department for technical review. During the evaluation of these applications, the Department's staff will perform site investigations and review of the technical aspects of submitted plans and specifications.

6.2 Land Treatment of Sludge and Sludge Products

A State Permit is required for land application of sludge from water or wastewater treatment plants. The completed application will be submitted to the Department for technical review. A site inspection and preliminary concurrence by the Department is part of the evaluation process. A copy of the toxicity test analysis of the sludge must verify that the sludge does not qualify as a hazardous waste. If the sludge is deemed hazardous, it must be managed following hazardous waste regulations implemented by the Department. The Department also regulates landfilling and land treatment of nonhazardous industrial sludges.

6.3 Land Treatment of Agricultural Residuals

The Delaware Environmental Protection Act requires under Section 6003(a) that "No person shall, without first having obtained a permit from the Secretary, undertake any activity: (2) in a way which may cause or contribute to discharge of a pollutant into any surface or groundwater; ...". Over application, improper storage and timing of land application of agricultural residuals have contributed to contamination of both surface and groundwaters in the State.

6.4 The Division of Water Resources is currently studying alternative management programs for the land application of agricultural residuals. A proposed management program is expected to be circulated for public review by 1989. For the interim operators of systems which generate such residuals should consult their local conservation district for assistance in employing the guidance contained in this document and utilizing currently accepted residual management practices.

6.5 The Department recognizes that the general and technical public (i.e., consulting engineers, developers, local governments, public interest groups, etc.) may not be well informed concerning the requirements for obtaining appropriate permits for land treatment systems. The staff of the agency is available to provide assistance in determining permit application requirements, and administrative procedures for processing permit applications for the types of facilities discussed in these Regulations for land treatment of wastes.


7.0 Structure of Regulatory Documents and Procedures

Regulations and Guidance information are contained in a single document for easy use.

7.1 The requirements for sludge land treatment focus on:

7.1.1 the overall process for obtaining a permit

7.1.2 the reports and materials to be submitted

7.1.3 appropriate requirements for:

7.1.3.1 agricultural and silvicultural utilization

7.1.3.2 land reclamation sites

7.1.3.3 surface land disposal systems

7.1.3.4 sludge distribution systems

7.1.3.5 utilization or disposal at landfills

7.1.3.6 innovative systems

7.1.4 The actual soil science, agronomy, and land treatment science which are necessary to produce a Project Development Report are given before the Regulations in the guidance section of this document.

7.2 The requirements for land treatment of wastewaters follow a similar organizational framework. Requirements are established for:

7.2.1 the complete State review and permit approval process

7.2.2 the reports and materials to be submitted

7.2.3 the operational requirements

7.3 A detailed guidance document is also included to describe the soil science, hydrology, agronomy, and land treatment science necessary to produce the design reports used in the Department permit review process.

7.4 The Land Treatment of Agricultural Residuals follows a similar format. The initial section provides guidance on animal wastes. Preliminary application procedures that include soil testing and manure nutrient analysis are covered along with rates, timing, and methods of application. Regulations for the Land Treatment of Agricultural Residuals have been reserved to allow time for further study and research on appropriate residual management alternatives. Principal areas of study for future action are:

7.4.1 Siting of Animal Feeding Operations

7.4.2 Design and Management of Systems to Land Apply Livestock Manure

7.4.3 Control of Manure Odors

7.4.4 Disposal of Dead Livestock

A strong need to assess each site and waste type using the same decision process is thus built into this process. In this manner the diverse conditions in the State of Delaware can be routinely evaluated and an optimal design achieved to provide cost-effective land treatment which protects the environment.

8.0 Advisory and Technical Assistance

The assistance of one or more of the following technical groups will be helpful in any consideration of land treatment systems:

8.1 Cooperative Extension Agent

8.1.1 The extension office in each county of the state can serve as an early contact for discussions and information on land treatment systems. A call to this office will provide specific local information and access to state specialists on the extension staff at the University of Delaware. The extension staff periodically receives training on agricultural waste management and land treatment of wastes from specialists at the University of Delaware so that they may provide first-hand assistance. An early contact with the county extension office will provide a mechanism for gaining immediate assistance at the county level and obtaining in-depth help from state specialists in appropriate discipline areas such as engineering, soil science, crop science, economics, and community and resource development. Assistance for taking soil samples can be obtained from several county agricultural agencies including the county extension office. A copy of the soil test results is routinely sent to the county extension office to assist in understanding and implementing test recommendations.

8.1.2 The Cooperative Extension Service has a long history of helping individuals at the county level with program activities in agriculture, home economics, community and rural development, and youth work. Cooperative relationships have been developed with other agricultural service agencies and with the Department of Natural Resources and Environmental Control. The cooperative program to set the criteria and recommendations for livestock waste management systems which satisfy regulatory criteria, enhance environmental quality, and result in more efficient agricultural production serves as a model for assistance available for land treatment of wastes through the county extension office.

8.2 Soil Conservation Service

8.2.1 The Soil Conservation Service can help provide site evaluation assistance for land treatment of waste products including soil and other landscape limitations. SCS can provide detailed on-site planning, design, installation, operation, and maintenance assistance for agricultural waste management system.

8.2.2 SCS can also provide financial assistance for installing agricultural waste management facilities through long-term contracting with landusers. This financial assistance is available only within certain designated project areas where water quality degradation or other natural resource concern requires special emphasis. Assistance is provided through the watershed protection provisions of Public Law 83-566.

8.2.3 SCS technical assistance is provided through Soil Conservation Districts. Requests for this and other kinds of technical assistance should be directed to the district board of supervisors. Those with continuing need for assistance will find it worthwhile to enroll as a cooperator. A district has been established to serve each county of the State. The district office is usually located in conjunction with the SCS office in the county seat.

8.3 Consulting Engineers

8.3.1 There is a wide range of consulting engineers with experience in the design of waste treatment facilities. A listing of individual professional engineers and engineering firms can be obtained from the Delaware Association of Professional Engineers, 2005 Concord Pike, Wilmington, Delaware 19803 or the Consulting Engineer's Council of Delaware, 1300 North Market Street, Suite 501, Wilmington, Delaware 19801. A number of disciplines are required in the design of land application systems and a consultant with a variety of specialized skills should be solicited.

8.4 Soil Scientists and Agronomists

8.4.1 Rosters of registered or certified soil scientists and agronomists can be obtained from the American Registry of Certified Professionals in Agronomy Crops and Soils (ARCPACS), American Society of Agronomy, 677 South Segoe Road, Madison, Wisconsin 53371. Another source of information would be the University of Delaware, College of Agricultural Sciences Department of Plant Science, Newark, Delaware 19703.

8.5 Land Treatment Specialists

8.5.1 Several firms in Delaware have specialized in the evaluation and design of land treatment systems. Their staffs generally include engineers, soil scientists, agronomists, and other specialists who work almost exclusively on such systems. Firms which provide material testing, soils testing, and agronomic evaluations may be well suited to evaluate land treatment systems. Contact the Department for a current list of such firms.

8.6 Delaware Geological Survey

8.6.1 The Delaware Geological Survey (DGS) conducts systematic investigation of the geology of Delaware; exploration and research pertaining to the water, mineral and other earth resources of the State; preparation of reports and maps presenting its findings; and, provision of actual geologic and hydrologic information and advice to the citizens of Delaware. The DGS may be contacted at the University of Delaware, 101 Penny Hall, Newark, Delaware 19716, telephone number (302) 451-2833.

8.7 Other Appropriate Technical Experts

8.7.1 Other experts with experience in land treatment may also prove to be valuable. An experienced wastewater treatment plant operator who has direct "hands-on" knowledge of land treatment system operation should be consulted to understand the daily requirements and operating costs associated with such operations. Such an individual can advise the system owner on the proper training and abilities which will be required for a full-time operator once the system is constructed. Local farmers may be consulted with respect to management plan development. Their knowledge of crop planting, harvesting, and soil protection can prove to be invaluable as a first start in the evaluation of system design. Equipment manufacturers often offer training courses or literature which are available to the public. These manufacturers may be contacted if information is needed on specific or general equipment design or use.

9.0 Conclusion

9.1 The use of land treatment systems in Delaware is increasing because these systems provide a safe, economical, and environmentally sound method of waste management. Federal and State funds for the construction of municipal waste treatment facilities have begun to diminish. This reduction in federal government support creates a purpose to reevaluate the need for conventional "concrete and steel" wastewater treatment facilities. It is imperative that an expanded list of alternatives be made available.

9.2 This Policies and Procedures document has briefly introduced the subject of land treatment systems. More detailed information is presented in the following general technical guidelines:

Land Treatment of Wastewaters

Part II

Land Treatment of Sludges and Sludge Products

Part III

Land Treatment of Agricultural Residuals

Part IV (deleted)

Land Treatment of Waste Products

Part V

These sections are intended to provide procedural and technical assistance for the evaluation and implementation of land treatment systems.


10.0 Purpose

10.1 This section presents a discussion of land treatment of wastewater in Delaware and general guidelines for designing land treatment systems for both municipal and industrial wastewater.

10.2 The biological, chemical and physical processes involved in land treatment are varied, interrelated and complex. Since our knowledge of these processes and their application in practice is continually increasing, it is anticipated that this discussion will be revised periodically to keep it up to date with the state of the art.

10.3 The Department determines the minimum requirements for applying for a permit for land treatment of wastewater through the establishment of appropriate regulations. These minimum requirements are also subject to change as knowledge about land treatment increases. These specific requirements are not listed in this guidance section.


11.0 Introduction

11.1 Application of wastewater to land can be a viable alternative for treatment and disposal of municipal and many industrial wastewaters. The constituents in the wastewater are taken up by plants, fixed in relatively insoluble forms in the soil, evolve as gases, or leach into the groundwater. The basic performance criteria for a land-treatment system are that: (a) quality standards for ground water and surface waters are not exceeded, (b) the system does not present a significant health problem, and (c) the soil is not degraded so as to prevent future use for agriculture, forestry or other planned development.

11.2 This section discusses general principles of land treatment of wastewater, the basic considerations for designing, managing and monitoring a land treatment system, and the basic performance criteria for a land-treatment system. Specific technical information for design of land treatment systems should be obtained from the technical support agencies and technical references listed in the Appendix. The EPA Process Design Manual on Land Treatment of Municipal Wastewater (7) presents three types of application methods (treatment processes) for land treatment of wastewater: (1) slow-rate process, (2) rapid infiltration, and (3) overland flow. The slow-rate process using spray irrigation technology is most applicable to Delaware conditions and has been demonstrated to achieve water quality goals. It is therefore the focus of the following discussion.


12.0 Basic Considerations for Design

12.1 Design of any land-treatment system will need to consider the following items:

12.1.2 Wastewater characterization; volume and composition (including seasonal fluctuations);

12.1.3 Land requirements; land selection and evaluation of land's assimilative capacity for the wastewater; land area required; land acquisition; land preparation; adjacent land uses

12.1.4 Pretreatment requirements before land application; design of total system (pretreatment and land application)

12.1.5 Storage requirements

12.1.6 Application equipment and controls

12.1.7 Groundwater quality and use

12.2 Vegetation and site management; liming, pest management, harvesting, etc.; equipment requirements; crop or forest utilization potential; crop or forest production costs and returns

12.3 Buffer zones

12.3.1 Monitoring

12.3.2 Security

12.3.3 Overall operations and maintenance

12.4 A flow chart briefly outlining system design and approval is shown in Figure 1.

13.0 General Design Principles

13.1 The wastewater must be characterized, and the available land must be evaluated to calculate the allowable loading rate of each constituent in the waste, including the hydraulic loading. For certain heavy metals, the loading rate is determined from maximum allowable accumulative applications for a chosen life expectancy over which the system should operate without any irreversible degradation of the soil for agricultural purposes. From the calculated loading rates, the limiting constituent (the one requiring the most land) is determined.

13.2 As this point, pretreatment options can be considered to reduce the amount of land required. Management of the land treatment system must also be considered in setting loading rates and application limitations. Management of vegetation and sale or disposal of crops or trees must be considered. Application equipment must be chosen appropriate for the site, application rate and overall system operation, including crop or forest management. Storage should also be designed to provide safe retention during periods when application may not be possible.

13.3 The design should also preclude runoff of wastewater during application, minimize surface runoff transport from the site, preclude extended ponding, allow for appropriate buffer zones at the site perimeter, and allow for operation during freezing weather (unless it is opted to store wastewater during winter months), and include alarms and safety features that prevent over application and system failure. Also, odors must be controlled. Good standard operating procedures and monitoring plans should be designed to insure safety of workers and prevent environmental degradation of soil and water resources.

14.0 System Alternatives

14.1 To properly compare the costs of a land treatment system to alternative conventional treatment systems' costs, land treatment system costs should be based on optimal combinations of pretreatment and land treatment options. The pretreatment requirements for some constituents such as nitrogen and phosphorus will be less for land treatment than for conventional treatment processes. Pretreatment costs for additional removal of the limiting constituent should be compared to costs of acquiring more land for treatment.



Waste Characterization

 

 

Generator

 

 

Preliminary Site Selection

Site Evaluation

Site Selection - loading rates - area req’d

 

 

 

Owner

County Extension Agent

 

 

 

Generator

Soil Cons. Service

 

 

 

Public Health

DNREC

 

 

 

Rep. of Local Gov’t

Consulting Engineers, Agronomists, Soil Scientists

 

 

 

DNREC

Site Approval

 

 

 

LEGEND

 

 

Flow of procedure

 

 

Persons/agencies involved

 

 

Feedback for revision

DNREC - - - - Permit Issued

Figure 1. Flow Chart for land treatment system design and approval

14.2 Several alternatives exist as to management of the land and vegetative cover. Vegetative options include forage crops, grain crops, rotation cropping and trees. The required management intensity varies for different systems and is normally lower for trees and forage crops than for row crops. Realistic utilization potential and costs of production must be estimated to evaluate economic returns from the crop.

14.3 Various management and equipment options should be evaluated. There are various irrigation system alternatives such as center pivot, solid set sprinkler, and traveling gun. Various alternatives in storage requirements and disinfection requirements should also be evaluated to minimize costs while maintaining a safe system.

14.4 The options of buying or leasing land or farmer contracts should also be considered. For many municipalities and industries, buying the land and operating the system as a dedicated site for wastewater treatment (without environmental degradation to prevent further use for agriculture, forestry or other planned development) is likely most desirable. However, in some situations land lease agreements or farmer contracts may be less costly. Sites owned and operated by the wastewater generator will use the highest possible wastewater application rate compatible with waste treatment goals and protection of the environment. Sites which are privately owned may utilize application rates necessary only to supplement nutrient and water needs of the crops being grown.


15.0 Wasterwater Characterization

The first step in designing land treatment systems is to determine the composition of the wastewater so a judgment can be made if it is suitable for land treatment. If it appears suitable, then composition and annual generation rate can be used with site assimilative capacity to determine land area required.

16.0 Generating Source

Wastewater considered for land application usually is from municipal or industrial wastewater treatment plants. Wastewater and sludge from municipal plants may be relatively innocuous if the raw sewage is domestic. The potential for increased concentrations of metals, organics, etc. increases as industrial input to the system increases. Industrial wastewater ranges from relatively clean by-products such as those from certain food processing and fermentation industries to those which are toxic or hazardous even in small amounts and require special attention.

17.0 Characterization Parameters

17.1 Generation Rate. The quantity of wastewater generated per year must be determined so annual generation rate of constituents can be calculated. Variability in rate must also be considered because this variability can affect storage, cropping systems and land requirements. Most municipal treatment plants have a constant flow. However, those in seasonal use areas such as beach resorts will have large seasonal fluctuations. Industrial waste flows may be constant but will vary during plant shutdown periods or if batch processes are used.

17.2 Composition. The solids content of municipal wastewater does not pose a problem, however, screening may be necessary to remove trash introduced in ponds, storage lagoons, etc., so pumps and sprinklers are not damaged or clogged. Solids content of certain industrial wastewater may affect the selection of crops and the possible need to flush the system and the crop with clear water after irrigation.

17.3 Plant nutrient content must be determined so wastewater rates may be applied to supply adequate nutrients for good crop production but to prevent excess rates which exceed the assimilative capacity of the soil-crop system.

17.4 Salts are important from two standpoints. High concentrations of total dissolved salts can cause crop injury due to osmotic effect. High concentrations of Na in the absence of adequate Ca and Mg (expressed as sodium adsorption ratio [SAR]) will reduce soil permeability due to clay dispersion.

17.5 The trace metal concentrations are important because of their effect on crop production and on animal or human health. High accumulations of copper, zinc and nickel will cause crop injury before concentrations in the crop are high enough to be toxic to consumers of the crop. Lead has never been shown to cause toxicity in crops; and since plants normally do not translocate high amounts of lead to their shoots, there is little danger of lead injestion by consumers of the crop unless it is present on leaf surfaces.

17.6 However, in most crops cadmium can accumulate to concentrations that are not toxic to the crop but may be harmful to consumers of the crop. The most prevalent problems in humans due to excess cadmium ingestion are kidney and bone disorders.

17.7 It is important to know the organic content of wastewater (usually measured as COD1). Excessive COD loadings can cause anaerobic conditions at the soil surface, greatly reduce infiltration, and cause unpleasant odors.

17.8 Wastewater may contain specific organics that are resistant to decomposition or may be toxic or carcinogenic. Resistant organics such as chlorinated hydrocarbons, some halogenated insecticides, PCB's and PBB's may be present. These compounds are not absorbed from soil by plants, but irrigation may leave them on leaf surfaces which may be later ingested by animals fed hay from the site. Thus, if vegetation from the site is to be fed as hay and these constituents are known to be present, then the vegetation should be analyzed before use as livestock feed.

17.9 Experience over many years has shown the health hazard associated with land treatment of wastewater to be very low. However, an analysis for fecal coliforms in wastewater is generally required. Normal sanitation practices by workers and prohibition of growing crops for direct human consumption help alleviate concerns about the health hazard.

17.10 Representative Sampling. It is important that the wastewater sample analyzed be representative of the entire flow; thus, a scheme of periodic or composite sampling should be used. After the land treatment system is in operation, a regular analysis program should be set up so land treatment can be modified if wastewater composition changes significantly.

17.11 Wastewater Analysis Analysis of wastewater should be completed to determine essential plant nutrients, solids content, oxygen demand, important trace metals, pH and other critical constituents dictated by the type of industrial input. If it is suspected or known that inputs to the wastewater treatment system contain other potentially toxic substances or substances which would affect system design, the wastewater should be analyzed for these also.

17.12 1COD is more appropriate than BOD for land treatment system design.The microbial population in soil is much more diverse than the population in water and can bring about greater rates of organic matter decomposition.

17.13 Pretreatment and Source Reduction. In general, the principal objectives of pretreating wastewater prior to land treatment are to reduce solids and any toxic substances associated with the solids (e.g. heavy metals), reduce pathogens, and minimize or control odors. Also, for nitrogen containing wastewaters, the pretreatment method that results in the lowest production of nitrate is the most preferred method.

17.14 After wastewater analysis, one may find one or two constituents that reduce or limit the suitability of the wastewater for land treatment. Industries may find it economically feasible to make changes in their processes or increase the degree of pretreatment to reduce the concentration of the limiting constituent.


18.0 Site Evaluation and Section

Once the wastewater generation rate and composition are known, it is possible to determine the mass of constituents generated and to make a rough estimate of land area required. With this information in hand, one can begin to look for potential land treatment sites.County soil survey reports (if available) or soil maps from the local Soil Conservation Service (SCS) office and U.S. Geological Survey (USGS) topographic maps can be used to make an initial screening of potential sites.


19.0 Evaluation of Potential Sites

19.1 Parties Involved. The word "wastewater" has negative connotations for most people with little knowledge of waste treatment. Rumors that a land treatment system is being proposed in a given area can cause an emotionally charged condition among residents of that area. Therefore, it is important to involve a number of people in the site selection process so an environmentally acceptable site will be selected, residents of the area can be educated about land treatment and lines of communication can be kept open.

19.1.1 A representative of local government should be involved early in the planning stage so he will be informed and can communicate with concerned residents. He can also determine if the proposed site is compatible with the local land use plan.

19.1.2 The county agricultural extension agent can assist in agronomic or forest recommendations for the site and perhaps can also provide with the help of state extension specialists an educational program for public meetings to inform area residents about land treatment.

19.1.3 The local SCS office can provide information on soils on the proposed site and can develop a soil map of the area if one is not available.

A representative of the Division of Water Resources, Water Pollution Control Branch must be involved. They will conduct a site inspection to determine if the site is suitable. This office will receive the permit application.

19.1.4 It is the responsibility of the waste generator and his consultant to coordinate the site evaluation and selection. Obviously, the land owner will be involved by offering the land for sale, lease or use.

19.2 Site Identification and Screening. Potential land treatment sites are identified using existing soils, topography, hydrogeology and land use data. Usually, land areas near where wastewater is generated are evaluated according to their land treatment suitability. A deductive approach is used in that, first, any constraints that might limit site suitability are identified. Some of the main factors to consider are current and planned land use, topography, soils, groundwater depth and quality, surface water sources, flooding hazard, and size of site required.

19.2.1 Eventually, for permit application the location of the site shall be indicated on topographic and soils maps.

19.3 Field Investigations. Although much of the preliminary screening of potential sites is based on existing field data available from an SCS county soil survey or other sources, some level of field investigation is necessary. This starts with a visual exploration of the site to identify any possible site limitations such as presence of wet areas, rock outcrops, and locations of streams. The visual exploration is normally followed by a site-specific field investigation to define assimilative capacities and other design related factors. However, the amount of additional field investigation needed will depend on the site characteristics and where uncertainty exists. Too little field data may result in using incorrect values for design while too much will result in unnecessarily high costs with little refinement in the design.

19.4 The allowable wastewater loading is often dependent upon the drainage characteristics of the site. The importance of evaluating the total pathway of movement of the wastewater from the soil surface to groundwater or surface water outlets is discussed in Chapter 4 under "Removal by Drainage." The field measurements needed to evaluate drainage will depend on the site characteristics. A deep soil with high permeability and low slope will be easier to evaluate than a soil with moderate slope and restrictive layers near the soil surface. The potential for groundwater mounding or perched water tables near the soil surface should also be evaluated. If applied properly, the USDA watershed model DRAINMOD can provide estimates of lateral migration of shallow groundwater. The EPA design manual (7) discusses methods for estimating hydraulic loading based on: (a) vertical hydraulic conductivity of the most restrictive layer, (b) limitation on percolate nitrate concentrations, and (c) groundwater mounding near the surface. If the soil characteristics indicate that infiltration capacity of the soil surface may restrict hourly application rates of the sprinkler system, then the application rate must be reduced or a crop management scheme to enhance infiltration must be considered.

19.5 Again, requirements for field measurements will vary at each site, but an order of sequence of investigations that may occur as suggested in the EPA manual (7) is given in Table 1.

TABLE 1

Field Investigations in Typical Order of Testing and Information to Obtain

Field Test

Information to Obtain

1. Test pits and/or hand auger borings

Depth of profile, texture, structure, soil layers resticting percolation

2. Bore holes

Depth to groundwater, depth to impermeable layers.

3. Permeability

Expected minimum permeability of restrictive horizon.

4. Soil Chemistry

Specific data relating to crop and soil management, phosphorus and trace metal retention.

19.6 Although soils information from the SCS county soil surveys or previous farming or forestry records will indicate the productivity potential of the soil, soil samples must be taken from the site to determine soil chemistry and the soil's present status for growing the intended vegetation. From the results of the soil chemical analysis knowledge of vegetation and site management procedures and long-term erosion rates, the assimilative capacity for each of the important wastewater constituents can be determined.

19.7 The site should also be evaluated for land clearing requirements and possible drainage requirements. If land clearing is necessary, it should be done with minimal soil disturbance. Land should not be graded (e.g. to reduce slope) in land preparation because this will likely reduce permeability. If artificial drainage is necessary, the pollution impact of the drainage water discharge must be determined.

19.8 If a groundwater and/or surface water monitoring program is required for the particular system, monitoring points should be established early so background data can be collected before wastewater is applied.


20.0 Site Assimilative Capacity and Land Requirement

Each wastewater application site has a capacity to accept wastewater, bring about treatment, and channel decomposition products into environmentally sound pathways. One important step in land treatment design is to determine the site assimilative capacity so appropriate loading rates can be determined for each of the major waste constituents and from that the amount of land required. Municipal wastewater application is usually limited by hydraulic loading and/or nitrogen. The limiting constituent in industrial wastewater may be nitrogen, heavy metals or other constituents. The limiting constituent must be determined using the site assimilative capacity and waste generation rates.

20.1 The three basic types of site assimilative capacity are (Figure 2):

20.1.1 Above-ground removal of decomposition products from the site. This includes nutrient removal by crop uptake and subsequent harvest, CO2 and NH3+ volatilization, N2 or NOx loss from denitrification and loss of applied water by evapotranspiration.

20.1.2 Permanent storage in the soil. The most important examples are P fixation by reaction with Al and Fe and trace metal fixation by reaction with organic matter and various mineral fractions of the soil.

20.1.3 Removal from the site by drainage. Both anions (NO3- Cl- SO4=) and cations (Na+ K+ Ca++ Mg++) move with drainage water, but the anions move more rapidly since they are not attracted to the negatively charged soil particles. A portion of the applied water leaves the site by draining into the groundwater.

20.2 These three pathways must be considered in detail for each system design since the importance of each is a function of the site and the waste being applied.

21.0 Above-Ground Removal

21.1 Crop uptake of applied nutrients and subsequent removal by harvest is one of the main mechanisms of above-ground removal. This is the main way that N is removed from the site as long as N application rates are not much in excess of normal crop fertilization rates. If the soil on the site has a high P fixing capacity, crop removal may not be the most important method of P removal.

21.2 Removal of nutrients is a function of crop yield and nutrient composition. Consequently, any environmental factor that reduces yield (unbalanced fertility, low pH disease, etc.) will also reduce nutrient removal from the site. It must be recognized that as a crop is supplied with increasing amounts of a nutrient, the crop will use that nutrient with decreasing efficiency. Thus, although a crop may take up 400 lb N/acre per year,

21.3 this uptake may have been attainable only when higher amounts were applied. Tables of crop nutrient uptake seldom contain information on quantity of nutrient applied, length of growing season (e.g. Delaware vs. Florida), whether the crop was irrigated, etc. The designer must consider this information when preparing nutrient balances and vegetation management schemes.

21.4 For design purposes loading rates that supply available nutrients at a rate that has been shown or that can be logically estimated to pose no pollution hazard should be used. Current fertilizer recommendations for crops in Delaware (11) are probably a good baseline for setting wastewater-applied nutrient uptake rates for most nutrients. Adjustments in rates can then be made based on ammonia volatilization losses, increased denitrification potential, P fixing potential of the particular soil, increased crop uptake due to irrigation and local experiences with similar soils (and similar management, if possible). Adjustments in yield, crop uptake and fertilization for irrigation should be made using data for the same crop and similar soils and climate if available. Also, N applications (and hydraulic loading) may have to be adjusted because of excess nitrate in drainage water. Nutrient uptake rates to trees are less well established than for forage and row crops.

21.5 Generally, much of the N in wastewater is in the NH4+ or NO3- form which is available to plants. Also, it is likely that most of the organic N in wastewater will become available during the growing season when soil organisms are active. However, if the wastewater is high in organic N and comes from a source that indicates the organic N will be slow to mineralize, then a laboratory incubation of the soil-wastewater mixture may be needed to determine N availability.

21.6 Phosphorus availability is more difficult to determine because of its fixation by soil. However, if incubations are conducted with soil from the proposed site, P as well as N availability could be estimated.

21.7 Gaseous loss of waste constituents is another mechanism of above-ground removal. Evapotranspiration (ET) of applied wastewater is determined by climate and soil moisture content. Data on potential ET (PET)1 are available for Delaware and can be used to calculate water loss by this mechanism. 21.8 Release of carbon dioxide (CO2) by microorganisms decomposing organic matter in wastewater is the mechanism for carbon removal from the site. Consequently, the soil must be kept aerobic to facilitate decomposition and to prevent odors and sealing that occur when the soil is anaerobic. Assimilative capacity of soil for organic matter can be estimated using the oxygen (O2) diffusion rate in soils as a function

21.8 1PET is the rate of ET when the site is completely vegetated and soil moisture does not limit ET. This is generally the case with land treatment systems for wastewater since irrigation keeps soil moisture high. of soil moisture content. Organic loading rate can be critical if high organic matter wastewater is irrigated because O2 supply is decreased not only by the increase in soil moisture (thereby reducing O2 diffusion rate) but also by the high biological and chemical O2 demand of the wastewater.

21.9 Certain industrial wastes contain organic compounds that may be resistant to decomposition and/or toxic to vegetation. Potential toxicity and rate of decomposition of these compounds must be determined from the literature or from actual tests so the site assimilative capacity can be determined.

21.10 Significant quantities of NH3 may be lost from the site by volatilization. If wastewater contains appreciable quantities of NH4+, then NH3 may volatilize during irrigation depending on wastewater pH, temperature, wind speed and droplet size. The EPA design manual (7) states that losses can be up to 10 percent of applied N if wastewater pH is 7.0 or above.

21.11 Gaseous N losses also occur when NO3- is reduced to N2 or oxides of N via microbial activity (denitrification). Several conditions must be met for denitrification to occur: anaerobic conditions, available carbon as an energy source for the organisms and a source of NO3-. Although land treatment systems must remain aerobic to function in the soil, denitrification can occur if carbon is available and NO3- diffuses into the site. Denitrification losses are difficult to measure under field conditions, but there is some evidence from research that wastewater irrigation increases denitrification rates. Denitrification can be affected by frequency of application, hydraulic loading, nitrification, and the inherent denitrification potential of the soil at the site. Denitrification losses are generally reported to vary between 10 and 35 percent of the applied available N. Most soils suitable for wastewater application have denitrification potentials less than 100 lb/acre per year.

21.12 The N assimilative capacity of the site is the sum of the fertilizer N recommendation (under irrigated conditions) and the denitrification potential (and any waste or management-induced denitrification if it can be shown to be appreciable), with adjustments for ammonia volatilization losses at application.For general guidelines in design, the EPA design manual (7) recommends that the sum of volatilization losses and denitrification be assumed to be in the range of 15 to 25 percent of the applied N. Certain conditions may exist which denitrification is appreciable in areas adjacent to the irrigated site that receive drainage water. Recent research has shown that nitrate in drainage water from well-drained areas will be denitrified if it moves through adjacent poorly drained areas (e.g. marsh, swamps, base of slopes, etc.).This process may be designed into the N balance for the land treatment system if the necessary conditions exist.


22.0 Permanent Storage in Soil

22.1 Most soils in Delaware have high P-fixing capacities because of their high Fe and/or Al content. Reaction products of P with Fe and Al are relatively insoluble so P does not move appreciably when applied to soil. The P fixation capacity of the soil is mainly a function of soil texture, to some extent drainage class, and previous P fertilization. The high P fixation capacity of Delaware soils will prevent P from leaching to the groundwater except in very sandy soils (e.g. Coastal Sussex) or at very high P loading rates.

22.2 A greater potential hazard than leaching to groundwater is P enrichment of surface water by P carried in eroded soil or runoff from fields receiving wastewater. Since the ratio of P/N in many wastewaters is much higher than the P/N ratio required by crops, application at rates to supply the N needs of the crop will result in application of large excesses of P. Consequently, the P concentration in topsoil will increase rapidly.

22.3 To minimize the potential P enrichment of surface waters, it is important that conservation measures be used to minimize erosion and adequate buffer zones be maintained between the site and surface water so sediment in runoff will be redeposited prior to reaching the watercourse. For this reason grass and forest vegetation are preferred over row crops that have exposed soil throughout the growing season.

22.4 Heavy metals react with a variety of soil constituents to form relatively insoluble compounds. The cation exchange capacity (CEC) is currently used as a measure of the soil's potential to tie up heavy metals. Table 2 presents current USEPA guidelines (and regulation for Cd) for land application of wastes containing heavy metals. Notice that soil pH must be kept at or above 6.5 for these rates to be used.

22.5 Since soils have finite capacities to retain phosphorus and trace metals, a useable site lifetime may be defined. For typical municipal wastewaters with low industrial input the site lifetime may exceed 100 years for phosphorus and several hundred years for trace metals. Site life for industrial wastewater systems must be evaluated on a constituent by constituent basis and site assimilative capacity for each. The concept of "site life" should not be interpreted to mean that at the end of the site life the land is no longer useable for agriculture. Quite the contrary. Sufficient safety factors have been incorporated into the guidelines so normal agricultural production can continue after waste additions are stopped.

23.0 Removal by Drainage

An important mechanism of removal of wastewater from a site is downward movement through the soil to the groundwater. To adequately estimate a hydraulic loading that will not result in site failure from overloading, one must consider the entire pathway from soil surface to outflow of groundwater through natural discharge areas or artificial drains. For analysis the pathway can be divided into three sections:

23.1 Infiltration and storage in the topsoil.

23.2 Downward movement through the soil and parent material to the groundwater

23.3 Movement of groundwater to an outlet and into surface water.

23.4 Most Delaware soils consist of a fairly permeable A horizon over a B horizon with somewhat lower permeability. Irrigated water enters the A horizon at a relatively rapid rate and is temporarily stored there until it can move slowly through the B horizon or, on sloping areas, move laterally along the top of the B. During wet periods or with high loading rates, this laterally moving water may appear at seeps or springs at the bottom of a slope.

23.5 In determining a hydraulic loading and an application rate, one must be certain that the soil has sufficient infiltration capacity and storage capacity in the A horizon to accept water, store it and then permit drainage at a rate which allows the soil to reaerate rather rapidly. Reaeration is necessary to assure aerobic decomposition of the organic material in the wastewater. Otherwise, anaerobic conditions will exist with subsequent nuisance odors and possibly sealing the soil by slimes formed during anaerobic decomposition.

23.6 Infiltration capacity is a function of soil texture and structure, initial moisture content, vegetative cover, and temperature (e.g., frozen soil). Storage capacity is a function of pore size distribution.

23.7 The rate of vertical movement through the soil is controlled by saturated hydraulic conductivity or permeability (Ksat) of the most restrictive soil layer. Procedures developed by EPA for estimating this downward movement use 4 to 10 percent of the Ksat of the restrictive horizon as the drainage rate (percolation) used in calculating allowable weekly or monthly hydraulic loading rate (7). EPA's procedures (7) for calculating design hydraulic loading rate uses a monthly water balance for precipitation, evapotranspiration (ET), and percolation (with adjustments for periods of non-operation due to management activities). The results of this monthly water balance should also be compared with the results of the monthly percolate nitrate concentration calculations to determine which is limiting, especially when vegetation is not present. Also, in some cases, the reaeration requirement and the A-horizon storage mentioned previously can be more limiting than the Ksat of the most restrictive layer.

TABLE 2

Current USEPA Guidelines(5) For Zn, Cu, Ni, and Pb and Regulations(3) for Cd Application to Land Used for Production of Food-chain Crops

Soil Cation Exchange Capacity (meq/100g)(1)

Metal

0-5

5-15

>15

 

Cumulative Limit - lb/ac (Kg/ha)

 

 

Pb

500(560)

1000(1120)

2000 (2240)

Zn

250(280)

500 (560)

1000 (1120)

Cu

125(140)

250 (280)

500(560)

Ni

125(140)

250 (280)

500(560)

Cd

404(5)

8.9 (10)

17.8 (20)

Annual Cd application rate not to exceed 0.44 lb/ac (0.5 Kg/ha)

NOTE: SOIL MUST BE MAINTAINED AT pH 6.5 OR ABOVE WHENEVER FOOD- CHAIN CROPS ARE GROWN UNLESS PLANT NUTRIENT NEEDS AND SOIL CHEMISTRY PRECLUDE SUCH VALUES WITHOUT EXCESSIVE LIME ADDITION, BASED NOT ON COST BUT ON UNREALISTIC TONNAGE OF LIME/ACRE. In such cases, lime additions suitable to the vegetation used are to be applied in conjunction with annual metal monitoring of the vegetation.

23.8 On sloping sites which have subsoils with lower values of Ksat, some of the applied water will move laterally above the zone of restricted Ksat. In this case water may move through a relatively small cross-sectional area. Thus, application rates have to be limited to prevent prolonged saturation of the topsoil down slope with subsequent surfacing of the water before adequate treatment has occurred.

23.9 Rate of movement of groundwater from the site to an outlet is controlled by the groundwater gradient (i.e. difference in elevation of the groundwater under the site and at the outlet) and the Ksat of the material through which it is moving. The groundwater level under the site may rise due to irrigation leading perhaps to a mounding condition. One must select a loading such that the groundwater does not rise so close to the surface that wastewater does not receive adequate treatment prior to entering the groundwater. The EPA design manual on wastewater (7) gives methods for calculating: (a) subsurface drainage rates to surface water (ditches) and (b) groundwater mounding, or perched water table. Although these topics are presented in the EPA design manual mainly for high infiltration process design (very high application rates), the methods are applicable to slow rate systems as well.

23.10 Drainage water moving to the groundwater also carries with it waste constituents not removed by storage in the soil or above-ground removal. To protect groundwater quality, concentrations of these constituents must not exceed allowable limits determined by groundwater classification (e.g. 10 mg/L for NO3--N in potable groundwater). Concentrations of waste constituents not specifically covered in these regulations must not exceed concentrations in the National Interim Primary and Secondary Drinking Water Regulations (2). The EPA design manual on wastewater irrigation (7) contains an annual mass balance method1 of determining loading rates which will prevent excess concentrations of NO3--N from entering the groundwater. This method can also be used for some other constituents as well, e.g. Cl- and SO4= .

23.11 It is important that if a wastewater containing an imbalance of sodium to calcium and magnesium is applied that sodium not be allowed to accumulate appreciably on the cation exchange sites. If excessive accumulation of Na does occur, clay particles disperse and hydraulic conductivity is reduced. The dispersion hazard increases as the clay content of the soil increases and as the ratio of Na to (Ca + Mg) in the wastewater increases. This ratio, the sodium adsorption ratio (SAR), influences the extent of retention of Na on the exchange complex.

23.12 Wastewater with an SAR greater than 15 will cause reduction in hydraulic conductivity in all but very sandy soils. Over long periods of time wastewaters with SAR's less than 15 can cause reduced hydraulic conductivity.

23.13 1N draining to groundwater = N applied minus N removed by crop harvest, NH3 volatilization, and/or denitrification (i.e. above-groundremoval, Fig. 4-1).

23.14 Gypsum (CaSO4= . 2H2O) may be used to supply a source of relatively soluble Ca to prevent Na accumulation in the soil. However, gypsum rates must be limited to those that will not raise groundwater SO4= concentrations above 250 mg/L. Municipal wastewaters with little industrial input rarely have SAR's above 2 to 5 and therefore do not represent a design limitation.

24.0 Land Requirement

24.1 After the wastewater has been analyzed for appropriate constituents and the site assimilative capacity for those constituents determined, the amount of land needed for environmentally sound wastewater application can be calculated.

24.2 The quantity of each wastewater constituent generated per year is calculated using annual wastewater generation rate and constituent concentrations. These values divided by the annual site assimilative capacity yield the land area required. After the area required for each constituent is determined, the limiting constituent, i.e., the constituent requiring the most land, determines the amount of land needed for the land treatment system.

24.3 Hydraulic loading is often the limiting factor with municipal wastewater. Typically, the amount of land required for 1 M gal/d of wastewater based on hydraulic loading may vary between 120 and 300 ac. depending upon the hydraulic properties and management of the site. After the area required for actual application is determined, additional area for buffer zones must be determined.

25.0 Systems Management

25.1 Lack of proper management of land treatment systems can result in environmental degradation and possible irreversible damage to the land. Various management schemes may be used to obtain the same level of waste application and treatment. Therefore, the land treatment system manager must be knowledgeable about all phases of the system to know how changes in management or operational performance of one system component affects other system components. He must be particularly knowledgeable about application hardware and agronomic or forest management. The objective of this chapter is to present basic considerations in choosing the application method, application equipment, storage requirements, cropping system, and application schedules.

1For constituents stored in the soil, the annual site assimilative capacity is determined using the site life.


26.0 Storage Requirements

Sufficient storage capacity must be provided for the maximum amount of wastewater generated over the maximum length of time for which irrigation is impractical. Non-application periods depend primarily upon the climate (e.g., excess soil moisture due to precipitation; freezing conditions) and the crop grown (e.g., crop growth stages that prohibit wastewater application). The storage facility capacity must consider a minimum reserve volume, rainfall storage for the design storm, volume for sludge accumulation and storage for non-application periods such as crop harvest and establishment, inclement weather, frozen soil, equipment breakdowns and flow equalization to name a few. The storage facility should be constructed properly to preclude seepage to groundwater and to preclude overflow except when rainfall exceeds design basis, in which case the possible impact of potential overflow must be considered.


27.0 Application Equipment

27.1 There are two basic types of irrigation systems: stationary (permanent) and mobile. The stationary system requires a higher initial investment but less annual labor. Mobile irrigation systems may be moved either manually from site to site or may traverse areas of land using a guidance system. Overall application amounts are controlled by the amount of time the system is in operation since the rate of application is generally fixed by the system design and the equipment chosen.

27.2 Drift of spray and aerosols should be minimized by selecting proper equipment, good application times (low wind) and adequate buffer zones. Runoff should be avoided, and this is dependent mainly upon application rate and moisture condition of the soil at the time of application. Uniformity of application can be affected by wind (drift), vegetation and uneven topography. Also, uniformity of application varies with type of irrigation system and sprinklers. Lack of uniformity should be considered in the design to prevent localized ponding or runoff.


28.0 Crop-Soil Management and Scheduling

28.1 The cropping system and soil hydraulic properties largely determine when and how much wastewater may be applied. Crops vary in their consumptive use of water (evapotranspiration), water tolerance for wet conditions and nutrient requirements. Different crops also require various degrees of management intensity and diversity of equipment and have varying potential economic returns for reducing the costs of the land treatment system. Forests and forage crops are attractive for wastewater treatment because of relatively low management requirements compared to row crops. Further, constant vegetative cover by trees or grasses promotes high infiltration and evapotranspiration and reduces potential for erosion and runoff. Although there may be more potential economic return from row crops or a diversity of crops rather than just trees or forages, the required intensity of management and the farm equipment requirements increase with row crops. Markets must also be considered when selecting the vegetation.

28.2 Whether the crop is trees, forage, or row crops, all have requirements for site preparation, planting, crop maintenance, weed and pest management, harvesting, and sale or disposal of harvested material. Wastewater application will not be possible during certain periods because of required tasks, e.g. cutting and baling hay, or restrictions such as the minimum period between application and harvesting. Wastewater application scheduling must mesh with the crop management scheduling.

28.3 Wastewater application and schedules and any supplemental fertilization must be matched to the crop's nutrient needs. Application of nutrients during non-growing periods can be accomplished if the form of nutrient applied is primarily one that is stored and not available for movement in percolating water. For instance, irrigation of nitrogen principally in the organic and ammonia forms results in storage on site. Whe nitrification occurs, presumably due to warmer soil temperatures and microbial activity, plants will also be actively taking up nitrate and/or denitrification will occur.

28.4 Fertilizer recommendations for P2O5 and K2 O should be regularly determined by soil tests. The University of Delaware College of Agriculture Soil Testing Laboratory, Department of Plant Science, routinely runs soil tests. Fertilizer N recommendations are based on the crop being grown with allowance for residual N from the previous crop in some cases. Consequently, fertilizer recommendations on their soil test reports will always indicate that N fertilization is needed. Ignore this recommendation and apply wastewater based on design loading rates. Also, the P2O5 recommendation may need adjustment based on the design loading rate for the particular soil's P adsorption capacity and chosen site life.

28.5 Fewer data are available on growth response to wastewater fertilization of forests. Infiltration rates are normally high for forest soils, but the uptake of nutrients is normally lower for trees than for forages or row crops. Forestry specialists should be consulted for managing forest land treatment sites because there is relatively little information available in publications on forest management compared to the Delaware Agricultural Extension Service's bulletins on forage and row-crop management.

28.6 Irrigation scheduling must also take into consideration the soil moisture conditions and adjust scheduling or amount of application when necessary to prevent surface runoff or ponding and to allow adequate reaeration of the soil's A horizon for proper crop growth and wastewater treatment. Soil moisture measurements or tensiometers may be helpful in making irrigation decisions for sensitive crops.

28.7 Regardless of what crop is grown, land treatment systems must be managed in accordance with good agricultural practice. Sites receiving a high hydraulic loading will require careful management not common to normal farm operations due to the constant wet soils and need to control equipment access. It is advisable to hire a capable manager and require the manager to be familiar with and operate the system in accordance with a detailed "Operations and Management" manual. Adequate safety allowances should be built into the design to allow for a range of expected management capabilities as well as variability in crop yield and uncontrollable variables such as weather. The system should be designed using realistic average crop yields and nutrient uptake, not the maximum which may occur only one year in ten. If the crop removal of nutrients is not as much as designed for, then there is potential for environmental degradation. To assure nutrient removal from the site, marketing or utilization of harvested crops should be planned in advance. Timely crop harvest and removal from the site is necessary to maintain design nutrient balances.

29.0 Monitoring Guidelines

A monitoring program serves several purposes and may include several or all of the following:

29.1 To verify system performance as designed relative to wastewater treatment and environmental impact as prescribed in the permit.

29.2 To assess the vegetative-soil system to insure that viable vegetative cover is maintained and to provide information for effective site and vegetation management.

29.3 To determine safety of utilization of any vegetation harvested from the site or consumed by animals.

29.4 To monitor effectiveness of pretreatment processes and the generation rate and composition for any significant changes.


30.0 Record Keeping

The monitoring requirements and record-keeping requirements should be specified in the system design before it is approved. Record keeping is the responsibility of the operator or manager of the land treatment system, but records will be checked by Department personnel for accuracy and completeness.


31.0 Background Data

For certain items, monitoring should begin before the initiation of land application of wastewater. Such items may include phosphorus level in the soil, nitrate in the groundwater, and depth to groundwater. The background monitoring period and the amount of data required will depend upon the potential problems identified for the wastewater constituents to be applied and the characteristics of the site.


32.0 Waste Stream Monitoring

The wastewater production rate and composition should be determined routinely. The frequency of sampling and number of constituents to be analyzed will depend on the variability of the wastewater over time and the pollution potential of various waste constituents.


33.0 Groundwater and Surface Water Monitoring

33.1 Groundwater should be monitored on a periodic basis to evaluate increased levels of potentially mobile pollutants such as NO3--N. The number and location of wells required will depend on site characteristics, present groundwater quality and potential for groundwater degradation beyond allowable limits. Wells should be cased to prevent contamination from surface water. Groundwater monitoring is generally conducted in three primary areas:

3.1.1 up-gradient of the land treatment site to provide background information,

3.1.2 directly beneath the site, and

3.1.3 down-gradient of the site.

33.2 Parameters should be classified in priority levels and monitored at different frequencies depending upon priority level. Operational changes in the treatment process and/or waste stream character may dictate moving parameters from one priority level to another.

33.3 Surrounding surface waters should be monitored essentially for the same parameters as measured in groundwater, plus constituents that may move in surface runoff and erosion such as P and NH4 + N. Sampling locations will depend upon the hydrologic characteristics of the site. Channels or ditches and subsurface drains which drain the site should be sampled as a high priority.


34.0 Soil Monitoring

Soil should be monitored for the key constituents which accumulate in the soil and are potentially harmful. Incremental sampling depths should be small enough to accurately determine changes in concentration, particularly near the soil surface. Also, sampling for agronomic parameters should be conducted routinely to ensure optimal performance of the soil/plant system and that the required pH is maintained.

35.0 Crop Monitoring

Crop monitoring should evaluate potential utilization problems of the harvested forage or grain, such as trace metals and PCB's if present in the waste. Frequency of sampling and parameters to be monitored will depend upon the utilization of the crop and the wastewater constituents being applied. For example, forages being harvested as hay to feed livestock should be monitored for PCB's and cadmium if PCB's and cadmium are applied in the wastewater and can accumulate on the leaf surfaces. Crop monitoring may also be used to evaluate nutrient deficiencies of minor elements or other vegetative growth problems so supplemental additions can be made to achieve optimum plant growth and wastewater nutrient uptake.

36.0 Public Health Protection

36.1 Many wastewater land treatment systems have operated successfully for years without public health problems. However, the public must be educated about the effectiveness of these systems in treating wastewater while minimizing public health hazards. Public health protection sometimes becomes the major issue in choosing land treatment over conventional waste treatment which discharges wastewater to rivers or streams. The EPA design manual (7) has a chapter on "Health and Environmental Effects." The possible health effects considered to be the major ones are presented here.

36.2 The main public health concerns that must be considered in designing and managing land treatment sites are:

36.2.1 microorganisms surviving to enter drinking water, transferred by grazing animals or inhaled in aerosols leading to possible infection or disease

36.2.2 trace elements such as cadmium getting into food chain or drinking water leading to possible toxicity levels

36.2.3 trace organics and synthetic organic compounds getting into drinking water or the food chain leading to possible toxicity levels and carcinogenesis nitrate nitrogen additions to drinking water aquifers leading to potential health problems or methemoglobinemia (blood disorder) in infants.

36.3 Low numbers of pathogenic bacteria and viruses and some intestinal parasites may survive the sewage treatment process and be present in wastewater. Bacteria and viruses are greatly reduced by primary and secondary treatment, but as a general policy, active disinfection is required in Delaware as an additional precaution (see Subsection 303 of these regulations). The Department will determine disinfection requirements for irrigation of wastewater on a case-by-case basis. When "active" disinfection is not proposed by the applicant or consulting engineer, adequate justification must be submitted for consideration.

36.4 The EPA has issued general guidelines for pre-irrigation treatment of municipal wastewater (7) which are less stringent than Delaware's requirements. EPA's general guidelines are listed here as a matter of information:

36.4.1 Primary treatment - acceptable for isolated locations with restricted public access and when limited to crops not for direct human consumption.

36.4.2 Biological treatment by ponds or inplant processes plus control of fecal coliform count to less than 1,000 MPN/100 mL - acceptable for controlled agricultural irrigation except for human food crops to be eaten raw.

36.4.3 Biological treatment by ponds or inplant processes with additional BOD or suspended solids control as needed for aesthetics plus disinfection to log mean of 200/100 mL (EPA fecal coliform criteria for bathing waters) - acceptable for application in public access areas such as parks and golf courses.

36.5 Concerning chlorination for disinfection, trace organics (e.g. trihalomethanes) may be produced when wastewaters containing organic material is chlorinated. More research is needed in this area, but chlorination should be used with caution where drinking water supplies are potentially affected.

36.6 Several measures in addition to disinfection can be used to reduce bacterial and viral exposure through aerosols. These measures include:

operating sprinklers during daylight hours increases the number of microorganisms killed by ultraviolet radiation and drying;

36.7 use of downward-directed, low-pressure sprinklers results in fewer aerosols than upward-directed, high-pressure sprinklers;

36.8 buffer zones may be used to separate the spray source and the general public;

36.9 planting vegetation, particularly trees, around the site in the buffer can reduce the aerosols leaving the site by causing vertical dispersion and trapping.

36.10 Growing vegetables or grazing animals on an actively irrigated land treatment site is generally prohibited because of the potential for transfer of pathogens and intestinal worm eggs (see Subsection 308 of these regulations). Other considerations that prohibit grazing are soil compaction by animals, which affects infiltration rates, and the problem of essentially little net removal of nutrients during grazing. If wastewater applications are terminated, the following precautions are recommended when a wastewater with domestic sources is irrigated:

36.11 Grazing by animals (other than lactating dairy cows) whose products are consumed by humans should be prohibited for at least one month after irrigation ceases.

Grazing by lactating dairy cows should be prohibited for at least one year because of the potential of intestinal worms being transferred into milk by udder contamination.

36.12 Growing vegetables and root crops, which are eaten raw, should be prohibited for at least 18 months.

36.13 For pathogen considerations (when the wastewater contains domestic wastes), hay should not be cut for at least four days after application of disinfected secondary effluent. If the wastewater contains appreciable amounts of synthetic organic compounds or cadmium (or other potentially harmful trace elements), then the forage should be monitored for potential toxicity problems to animals or possible food-chain effects, especially in the case of feeding hay to lactating dairy cows.

36.14 EPA requirements for limiting cadmium application to land (Table 2) and design considerations to prevent nitrate pollution of groundwater have been previously discussed in Chapter 4.

37.0 Economic Considerations

37.1 The number of publicly owned municipal wastewater irrigation systems in the United States was reported by EPA to be 839 in 1981 (7). The addition of industrial and privately owned land treatment systems and the publicly owned systems installed since 1981 likely brings the total number of land application systems to over 2,000 systems in 1987. Therefore, many communities and industries have found land treatment to be an economical waste treatment alternative.

37.2 There is not a good summary of economic data on land treatment systems in Delaware. However, enough systems have been installed in other states to provide example calculations for a range of community sizes and situations where a land treatment system may be considered. he best sources of this information are other municipalities and industries that have land treatment systems and engineering consultants who have designed these systems.

37.3 Some EPA and U.S. Dept. of Agriculture (USDA) publications provide economic analysis of land treatment systems (8, 9, 10) for municipal wastewater. The EPA Process Design Manual (7) provides an example for wastewater irrigation which includes economic analysis based on the techniques presented in reference (8).

37.4 The USDA publication's cost analysis (10) resulted in the following conclusions for land treatment of municipal wastewater:

37.5 Land application of wastewater is a cost-effective method for advanced wastewater treatment.

37.6 Compared with conventional advanced wastewater treatment technologies, land application is less expensive for facilities treating less than 5 million gallons of wastewater per day and may be cost-effective for larger systems depending on land availability and distance from the treatment plant.

37.7 The publication also analyzes factors such as crop selection, land costs, effluent transmission, public health constraints, storage and hydraulic loading. This type of publication is limited in its applicability of economic data to situations other than those specifically used in its analysis, but the concepts of what economic factors and analysis techniques to use are applicable to other situations.

38.0 Appendices

38.1 Sources of Materials and Information Useful in Designing Land Treatment Systems (Subsection 1001)

38.1.1 County roadmaps

Maps, Delaware Dept. of Transportation

Division of Highways

Dover, Delaware 19903

38.1.2 Topographic maps

38.1.2.1 U.S. Geological Survey

38.1.2.2 These maps are also available from some engineering supply stores and the Government Printing Office

38.1.3 Aerial photographs

38.1.3.1 County Soil Conservation Service Office or

38.1.3.2 County Agricultural Stabilization and Conservation Service Office

38.1.3.2 Commercial aerial photographers

38.1.4 Soil maps, soil survey reports, soil series description sheets

38.1.4.1 County Soil Conservation Service Office

38.1.4.2 Some consulting firms have soil mapping capabilities

38.1.5 Technical manuals

38.1.5.1 See the "Literature Cited" and "Additional Literature on Land Treatment" sections at the end of the booklet.


39.0 Literature Cited

39.1 Chapman, H. D. 1965. Cation-Exchange Capacity. In C. A. Black (ed.) Methods of Soil Analysis. Amer. Soc. Agron. Madison, WI.

39.2 Code of Federal Regulations, Title 40, Protection of Environment, Part 141. 39.3 National Interim Primary Drinking Water Regulations. July 1, 1982.

39.4 Federal Register, Thursday, September 13, 1979. Part IX, EPA, Criteria for Classification of Solid Waste Disposal Facilities and Practices; Final, Interim Final and Proposed Regulations (as corrected in the Federal Register of Sept. 21, 1979) Vol. 44, pp. 53438-53468.

39.5 Jacobs, L. W. (ed.) 1977. Utilizing municipal sewage wastewaters and sludges on land for agricultural production. North Central Regional Extension Publication No. 52. Michigan State Univ., East Lansing, 48824.

39.6 Knezek, B. D. and R. H. Miller. 1978. Application of sludges and wastewaters on agricultural land: a planning and educational guide. EPA Report MCD-35.

39.7 Soil Conservation Service, USDA. 1975. Agricultural waste management field manual.

39.8 USEPA. 1981. Process Design Manual for Land Treatment of Municipal Wastewater. EPA 625/1-81-013.

39.9 USEPA. 1975. Cost of land treatment systems. EPA 430/9-75-003.

39.10 Young, C. E. 1976. The cost of land application of wastewater: a simulation analysis. Technical Bulletin 1555, ESCS, USDA, Washington, DC.

39.11 Young, C. E. 1978. Land application of wastewater: a cost analysis. Technical Bulletin 1594, ESCS, USDA, Washington, DC.

39.12 Parker, David R. and Leo J. Cotnoir, Jr. 1984. Fertilizer Recommendations for Delaware. Cooperative Bulletin No. 7, University of Delaware Cooperative Extension Service, Newark, Delaware.

40.0 Introduction

40.1 (Subsection 101) Purpose

40.1.1 This document provides regulations for the planning, design, and operation of slow rate land treatment systems for wastewaters in Delaware. These guidelines and regulations do not apply to overland flow or rapid infiltration systems. Furthermore, these regulations supersede Section 9 - Effluent Limitations for Land Disposal of Liquid Waste - Part I regarding Spray Irrigation of Liquid Waste as set forth in the Department's Regulations Governing the Control of Water Pollution, adopted March 15, 1974 and amended on June 23, 1983.

40.1.2 The Delaware Department of Natural Resources and Environmental Control encourages slow rate land treatment as an alternative to advanced wastewater treatment, particularly in environmentally sensitive areas of the State. In addition, slow rate land treatment, or wastewater irrigation, is encouraged for wastewater treatment in small to medium sized communities and industries where appropriate.

40.1.3 The term slow rate land treatment as used in these regulations refers to the advanced treatment of wastewater by irrigation onto land to support vegetative growth. These systems are designed and operated so there is no direct discharge to surface waters. The irrigated wastewater evaporates and transpires to the atmosphere or enters the groundwater through percolation. Organic constituents in the wastewater are stored in the soil or stabilized by soil bacteria. Organic and ammonia nitrogen are taken up by plants, nitrified by soil bacteria, lost to the atmosphere through denitrification, and leached groundwater. Phosphorus and other constituents are adsorbed in the soil profile and/or taken up by plants. Properly designed and operated wastewater irrigation systems produce a percolate water of high quality and thus protect ground and surface water resources.

40.1.4 The regulations outlined herein apply to wastewaters with and without domestic wastes. A distinction is made between the two types of wastewaters because of the public health issues associated with domestic wastes. Wastewater irrigation systems for industrial and animal wastes may depart somewhat from these regulations and, if so, will be evaluated by the Department on an individual basis.

40.1.4 The design and operation of wastewater irrigation systems is very site specific. This document is intended to provide regulations and general guidelines for design and operation of slow rate land treatment systems in Delaware. However, hydrogeologic and soil conditions vary widely throughout the State and site assessment and monitoring requirements may vary not only from region to region but even from site to site within the same region.

50.0 Sources of Information

The Division of Water Resources recommends the following additional sources of information for the planning, design and operation of slow rate land treatment systems

50.1 Organizations

50.1.1 American Society of Agricultural Engineers, 2950 Niles Road, St. Joseph, Michigan 49085.

50.1.2 American Society of Agronomy, 667 S. Segoe Road, Madison, Wisconsin 53711.

50.1.3 Delaware Agricultural Extension Service, College of Agriculture, University of Delaware, Newark, Delaware 19703.

50.1.4 The Irrigation Association, 13975 Connecticut Avenue, Silver Spring, Maryland 20906.

50.1.5 United States Department of Agriculture (USDA), Soil Conservation Service, Treadway Towers, Dover, Delaware 19901.

50.2 Technical References

50.2.1 Brady, N.C. 1974. The Nature and Properties of Soils, Eighth Edition. (ISBN 0-02-313350-3) MacMillan: New York, New York.

50.2.2 Cole, D., C. Henry, and W. Nutter. 1986. Forest Alternative for Land Treatment of Municipal and Industrial Wastes. University of Washington Press, Seattle, 592 pp.

50.2.3 The Irrigation Association. 1983. Irrigation, Fifth Edition. Silver Spring, Maryland.

50.2.4 Metcalf and Eddy, Inc. 1979. Wastewater Engineering: Treatment, Disposal and Reuse. (ISBN 0-07-041667-X) McGraw-Hill: New York, New York.

50.2.5 Overcash, M.R. and P. Pal. 1979. Design of Land Treatment Systems for Industrial Wastes - Theory and Practice. Ann Arbor Science: Ann Arbor, Michigan.

50.2.6 Reed, S.C. and R.W. Crites. 1984. Handbook of Land Treatment Systems for Industrial and Municipal Wastes. (ISBN 0-8155-0991-X) Noves Publications: Park Bridge, New Jersey.

50.2.7 Rich, L.G. 1980. Low Maintenance, Mechanically Simple Wastewater Treatment Systems. (ISBN 0-07-052252-9) McGraw-Hill: New York, New York.

50.2.8 Smedema, L.K. and D.W. Rycroft. 1983. Land Drainage: Planning and Design of Agricultural Drainage Systems. (ISBN 0-8014-1629-9) Cornell University Press: Ithaca, New York.

50.2.9 United States Department of Agriculture. National Engineering Handbook, Sections 15 and 16. Soil Conservation Service. Washington, D.C.

50.2.10 United States Environmental Protection Agency. 1981. Process Design Manual: Land Treatment of Municipal Wastewater. (EPA 625/1-81-013) Center for Environmental Research Information. Cincinnati, Ohio.

50.2.11 United States Environmental Protection Agency. 1983. Design Manual: Municipal Wastewater Stabilization Ponds. (EPA-625/1-83-015) Center for Environmental Research Information. Cincinnati, Ohio.

50.2.12 Water Pollution Control Federation, American Society of Civil Engineers. 1977. WPCF Manual of Practice No. 8: Wastewater Treatment Plant Design. Washington, D.C.

51.0 Definitions.

The following terms have the meanings indicated.

"Agricultural land" means land cultivated for the production of crops or used for raising livestock.

"Agricultural wastes" means wastes normally associated with the production and processing of food and fiber on farms, feedlots, ranches, ranges, and forests which may include animal manure, crop residues, and dead animals; also agricultural chemicals, fertilizers and pesticides which may find their way into surface and subsurface water.

"Crops for direct human consumption" means crops that are consumed by humans without processing to minimize pathogens before distribution to the consumer.

"Department" means the Department of Natural Resources and Environmental Control.

"Disposal" means the discharge, deposit, injection, dumping, spilling, leaking, or placing of wastewater, other liquid waste, or any constituent of it on or in the land, the air or any waters, including ground water, and includes any method of utilization that involves reuse of the nutrients at greater than agronomic rates.

"Food chain crops" means tobacco, crops grown for human consumption, and crops grown to feed animals whose products are consumed by humans.

"Free liquids" means liquids which readily separate from the solid portion of a waste under the following tests:

(a) EPA Plate Test. Place a 1 to 5 kilogram (2.2 to 11.0 lbs.)sample of waste on a level or slightly sloping plate of glass or other similarly flat and smooth solid material for at least 5 minutes. If a liquid phase separation is observed, the waste contains free liquids.

(b) EPA Gravity Test. The test protocol calls for a 100 ml representative sample of the waste from a container to be placed in a 400 micron conical paint filter for 5 minutes. The filter specified is a standard paint filter which is commonly available at hardware and paint stores. The filter is to be supported by a funnel on a ring stand with a beaker or cylinder below the funnel to capture any free liquid that passes through the filter. If any amount of free liquid passes through the filter, the waste is considered to hold free liquids.

"Household waste" means any waste derived from households (including single and multiple residences, hotels and motels, bunkhouses, ranger stations, crew quarters, campgrounds, and day-use recreation areas), not including sewage or septage.

"Impermeable" means having a hydraulic conductivity equal to or less than 1 x 10-7 cm/sec as determined by field and laboratory permeability tests made according to standard test methods which may be correlated with soil densification as determined by compaction tests.

"Land application" means the placement of liquid waste or treated liquid waste within 2 feet below the surface of land used to support vegetative growth.

"Land treatment" means a technology for the intimate mixing or dispersion of wastes into the upper zone of the plant-soil system with the objective of microbial stabilization, immobilization, selective dispersion, or crop recovery leading to an environmentally acceptable assimilation of the waste.

"Liquid waste" means any waste which is not a solid waste as defined for the purposes of these regulations.

"Person" means an individual, trust, firm, joint stock company, federal agency, corporation (including a government corporation), partnership, association, state, municipality, commission, political subdivision of a state, or any interstate body.

"Septage" means the liquid and solid contents of a septic tank.

"Sewage" means water-carried human or animal wastes from septic tanks, water closets, residences, buildings, industrial establishments, or other places, together with such groundwater infiltration, subsurface water, admixture of industrial wastes or other wastes as may be present.

"Sewage sludge" means sludges which derive in whole or in part from sewage.

"Sludge" means the accumulated semi-liquid suspension, settled solids, or dried residue of these solids that is deposited from (a) liquid waste in a municipal or industrial wastewater treatment plant, (b) surface or groundwaters treated in a water treatment plant, whether or not these solids have undergone treatment. Septage is included herein as sludge.

"Solid waste" means any garbage, refuse, rubbish, and other discarded materials resulting from industrial, commercial, mining, agricultural operations and from community activities which does not contain free liquids. Containers holding free liquids shall be considered solid waste when the container is designed to hold free liquids for use other than storage (e.g. radiators, batteries, transformers) or the waste is household waste which is not sewage or septage.

"Spray irrigation" means the loading rate for land treatment of wastewater which shall not exceed either the needs of the crop grown on the particular soil plus the other assimilative mechanisms (e.g. immobilization with organic material, volatilization, and leachate in compliance with drinking water standards), or the hydraulic capacity of the soil. The Department may require a lower loading rate if the design criteria for pathogens, metals or organics contained in these Regulations and generally accepted technical standards for land treatment technology (e.g. U.S. EPA Process Design Manual or Overcash, M.R. and P. Pal 1979 Design of Land Treatment Systems for Industrial Wastes - Theory and Practice cannot be achieved at a rate consistent with agricultural utilization.

"Storage" means the interim containment of liquid waste or treated liquid waste before disposal or utilization.

"Surface impoundment" means a natural topographic depression, and/or man-made excavation, and/or diked area formed primarily of earthen materials (although it may be lined with man-made materials) or remains unlined, and which is designed to hold an accumulation of liquid wastes or wastes containing free liquids. Examples of surface impoundments are holding, storage, settling, and elevation pits, ponds, and lagoons. Design requirements for storage are given in Section 900 of the Sludge and Sludge Products Regulations.

"Treatment" means a process which alters, modifies, or changes the biological, physical, or chemical characteristics of sludge or liquid waste.

"Treatment works" means any device and system used in the storage, treatment, recycling and reclamation of municipal sewage, or industrial wastes of a liquid nature, or necessary to recycle or reuse water at the most economical cost over the estimated life of the works, including intercepting sewers, outfall sewers, sewage collection systems, pumping, power and other equipment, and their appurtenances, extensions, improvements, remodeling, additions and alterations thereof; elements essential to provide a reliable recycled supply such as standby treatment units and clear well facilities and improvements to exclude or minimize inflow and infiltration.

"Wastewater treatment plant" means a facility designed and constructed to receive, treat, or store waterborne or liquid wastes.

52.0 Procedures for State Review and Approval

52.1 (Subsection 201) Proposal for Land Treatment

52.1.1 Title 7, Chapter 60 of the Delaware Code (the Environmental Protection Act) and these regulations govern procedures necessary to gain Department approval of slow rate land treatment systems. The steps outlined in Table 201-1 are in accordance with the Act and regulations. These steps are explained in the following sections. (Section 300 of these regulations contains a detailed discussion of required design considerations for slow rate systems.) Projects funded under the Federal Construction Grant Program (Title II of the Federal Clean Water Act) must meet all Federal funding requirements in addition to the steps listed in Table 201-1. Whenever the preparation of reports or other documents required by these regulations involves the practice of engineering, geology or other recognized profession under Delaware law, sufficient evidence of appropriate certification or registration in accordance with Title 24 of the Delaware Code must be submitted by the preparer.

52.2 Letter of Intent

52.2.1 The facility owner, his engineer or agent must submit to the Department a letter of intent to develop a wastewater irrigation system. It must indicate the projected design flow and wastewater characteristics for this system and proposed source(s) of project funding. In addition, owners of private domestic wastewater irrigation systems are required to execute a trust indenture with a local government body or other trustee approved by the Division. This trust indenture guarantees operation and maintenance of the facility in the event of operational or financial default by the owner.

52.3 Site Selection and Evaluation Report

52.3.1 Upon receipt of the letter of intent, the Department will inform the facility owner of the need for a "Site Selection and Evaluation Report". Potential land treatment sites must be identified and evaluated by the facility owner, and a preliminary soil survey conducted at the selected site(s).

52.3.2 Table 201-2 outlines information generally needed in the Site Selection and Evaluation Report. For Federal Construction Grant Projects, this information is included in the Facilities Plan Report. Additional information may be requested as needed.

52.4 Site Inspection and Concurrence

52.4.1 The Site Selection and Evaluation Report is submitted by the owner for Department review along with a request for general site concurrence. Upon receipt of the report, a Department representative will inspect the selected site(s). A site concurrence or denial letter will be written based on a engineering and geologic evaluation of site conditions. It should be noted that site concurrence is preliminary and pertains only to general wastewater treatment and application to the land. The letter will indicate what requirements are necessary to proceed with the project. Site concurrences for slow rate land treatment are valid for two years. If detailed design has not begun within this period, the Department may choose to reevaluate the project.


53.0 Design Development Report

53.1 After a site has been selected by the owner and accepted by the Department as suitable for slow rate land treatment, a "Design Development Report" must be submitted by the owner or his agent. This report shall include, but is not limited to, the information outlined in Tables 202-1 and 202-2. The report required by this section shall be prepared by qualified persons in soil science and land treatment.

53.2 The Design Development Report is submitted for Department review, and once accepted, becomes the basis of design for the project. In any event, the applicant must demonstrate that the proposed Land Treatment System will meet the regulatory objectives set forth in 300 of the Policies and Procedures for Land Treatment of Wastes and will not cause violations of State and Federal drinking water standards on an average annual basis or State Water Quality Standards for streams.


54.0 Permitting of Slow Rate Land Treatment Systems

54.1 The Department permits all slow rate land treatment systems. This permit incorporates a Department approved Plan of Operation and Management prepared for the facility by the owner or owner's engineer. No permit may be granted unless the county or municipality having jurisdiction has first approved the activity by zoning procedures provided by law.

54.2 Public Notice, Draft and Final Land Treatment System (LTS) Permits

54.3 Upon Department acceptance of the Design Development Report, the owner of the proposed facility must submit an application for a Department Land Treatment System (LTS) Permit. Upon receipt of the completed application for a permit, the Department will advertise receipt of the application and conduct any hearings in accordance with 7 Del.C., Ch. 60. The cost of the advertisement is to be borne by the applicant. If no hearings are held and if all requirements of these regulations.


55.0 Table 201-1 Steps for Delaware Department of Natural Resources and Environmental Control (DNREC) Review and Approval of Slow Rate Land Treatment Systems

55.1 Letter of Intent submitted to Department by owner or owner's representative.

55.2 Department response. Identifies need for:

55.2.1 Site Selection and Evaluation Report

55.2.2 Site Inspection

55.2.3 Design Development Report

55.2.4 Permit Application and Public Notice

55.2.5 Plans and Specifications

55.2.6 Plan of Operation and Management

55.2.7 Trust Indenture for privately owned facilities

55.3 Site Selection and Evaluation Report:

55.3.1 Submitted for Department review

55.3.2 Department conducts site inspection

55.3.3 Site concurrence or denial issued by Division

55.4 Design Development Report:

55.4.1 Submitted for Department review

55.4.2 Accepted by Department as the basis for facility design

55.5 Application for permit to apply treated wastewater to land:

55.5.1 Permit application requested from owner

55.5.2 Permit application completed and submitted to Department

55.5.3 Application reviewed and checked against design development report

55.6 Public Notice:

55.6.1 Public Notice drafted by Department

55.6.2 Public Notice advertised by Department; billing sent to owner

55.6.3 Public comment period

55.6.4 Public Notice requirements completed (hearing held if necessary)

55.6.5 Trust Indenture executed for privately owned facilities

55.7 Land Treatment System (LTS) Permit drafted by Division.

55.7.1 Industrial pretreatment requirements included if necessary

55.7.2 Draft permit and monitoring requirements sent to owner for comment

55.7.3 Draft permit modified if necessary

55.8 Plans and Specifications:

55.8.1 Submitted by owner for Department review with permit application

55.8.2 Checked against accepted Design Development Report

55.8.3 Approved by Department for construction and incorporated into final LTS permit

55.9 Plan of Operation and Management:*

55.9.1 Submitted by owner for Department review

55.9.2 Approved by Department

55.9.3 Incorporated into final LTS Permit

55.10 Final Land Treatment System (LTS) Permit issued.

55.10.1 Permit signed

55.10.2 Sent to facility owner

55.10.3 Facility construction begins

55.11 Certification of Construction Completion:

55.11.1 Submitted to Department by design engineer

55.11.2 Department conducts facility inspection to verify compliance with approved plans and specifications

55.12 Authorization to commence operation at design flow.

55.13 *While the steps shown in 55.9 are the preferred approach, in any case the Final Operation and Management Plan must be approved by the Department prior to issuance of an Authorization to commence operation at design flow (Item 55.12)


56.0 Table 201-2 Site Selection And Evaluation Report Information

56.1 Site Description:

56.1.1 Location map

56.1.2 Topographic map (7.5 minute quadrangle, scale 1:24000)

56.1.3 Soil survey map

56.1.4 Geologic and hydrologic conditions

56.1.5 Known cultural or historic resources (cemeteries, archaeologic sites, etc.)

56.2 Site Soil Characteristics:

56.2.1 USDA Soil Conservation Service soil series classifications

56.2.2 Narrative description for same including:

56.2.2.1 Texture

56.2.2.2 Permeability

56.2.2.3 Slope

56.2.2.4 Drainage

56.2.2.5 Depth to seasonal high water table

56.2.2.6 Depth to impervious strata

56.2.2.7 Erodibility

56.3 100 year flood elevation for site (if applicable).

56.4 Existing vegetative cover.

56.5 Existing land use.

56.6 Present land owner.

56.7 A detailed soil investigation report is required to be submitted with the Design Development Report (reference Sections 55.0 and 56.0 [Tables 202-1 and 202-2])have been fulfilled, a draft LTS Permit will be prepared for the slow rate land treatment system. The final permit will be issued upon submission and approval by the Department of the Plan of Operation and Management for the facility prior to start-up and operation. Upon granting written approval for operation, the Department shall give notice of such approval to any person who has submitted a written request for such notice.

56.8 Standard Permit Conditions. The following conditions shall apply to and will be included in all permits.

56.8.1 Compliance Required.The permittee shall comply with all conditions of the permit.

56.8.2 Renewal Responsibilities.If the permittee intends to continue operation of the permitted facility after the expiration of an existing permit, the permittee shall apply for a new permit in accordance with these regulations no later than 180 days prior to expiration.

56.8.3 Operation of Facilities.The permittee shall at all times properly maintain and operate all structures, systems, and equipment for treatment, control and monitoring, which are installed or used by the permittee to achieve compliance with the permit or these regulations.

56.8.4 Provide Information.The permittee shall furnish to the Department within a reasonable time, any information including copies of records, which may be requested by the Department to determine whether cause exists for modifying, revoking, reissuing, or terminating the permit, or to determine compliance with the permit or these regulations.

56.8.5 Entry and Access.The permittee shall allow the Department, consistent with 7 Del.C., Chapter 60, to:

56.8.5.1 Enter the permitted facility.

56.8.5.2 Inspect any records that must be kept under the conditions of the permit.

55.8.5.3 Inspect any facility, equipment, practice, or operation permitted or required by the permit.

55.8.5.4 Sample or monitor for the purpose of assuring permit compliance, any substance or any parameter at the facility.

56.8.6 Reporting.The permittee shall report to the Department under the circumstances and in the manner specified in this section:

56.8.6.1 In writing thirty (30) days before any planned physical alteration or addition to the permitted facility or activity if that alteration or addition would result in any significant change in information that was submitted during the permit application process.

56.8.6.2 In writing thirty (30) days before any anticipated change which would result in noncompliance with any permit condition or these regulations.

56.8.6.3 Orally within twenty-four (24) hours from the time the permittee became aware of any noncompliance which may endanger the public health or the environment at telephone numbers provided in the permit by the Department.

56.8.6.4 In writing as soon as possible but within five (5) days of the date the permittee knows or should know of any noncompliance unless extended by the Department. This report shall contain:

56.8.6.4.1 A description of the noncompliance and its cause;

The period of noncompliance including to the extent possible, times and dates and, if the noncompliance has not been corrected, the anticipated time it is expected to continue; and

56.8.6.4.2 Steps taken or planned to reduce or eliminate reoccurrence of the noncompliance.

56.8.6.5 In writing as soon as possible after the permittee becomes aware of relevant facts not submitted or incorrect information submitted, in a permit application or any report to the Department. Those facts or the correct information shall be included as a part of this report.

56.9 Minimize Impacts. The permittee shall take all necessary actions to eliminate and correct any adverse impact on the public health or the environment resulting from permit noncompliance.

56.10 Reopener. In the event that the regulations governing land disposal of wastes via spray irrigation are revised by the Department, this permit may be reopened and modified accordingly after notice and opportunity for a public hearing.

Specific Permit Conditions. A permit issued pursuant to these rules may include but not be limited to such information and conditions as the following:

56.11 Basis for Specific Permit Conditions.Conditions necessary for the protection of the environment and the public health may differ from facility to facility because of varying environmental conditions and wastewater compositions.The Department may establish, on a case-by-case basis, specific permit conditions. Specific conditions shall be established in consideration of characteristics specific to a facility and inherent hazards of those characteristics.Such characteristics include, but are not limited to:

56.11.1 Chemical, biological, physical, and volumetric characteristics of the wastewater;

56.11.2 Geological and climatic nature of the facility site;

56.11.3 Size of the site and its proximity to population centers and to ground and surface water;

56.11.4 Legal considerations relative to land use and water rights;

Techniques used in wastewater distribution and the disposition of that vegetation exposed to wastewaters;

56.11.5 Abilities of the soils and vegetative covers to treat the wastewater without undue hazard to the environment or to the public health; and

56.11.6 The need for monitoring and recordkeeping to determine if the facility is being operated in conformance with its design and if its design is adequate to protect the environment and the public health.

56.12 Duration of the Permit.The permit shall be effective for a fixed term of not more than five (5) years.

56.13 Limitations to Operation.Conditions of the permit may specify or limit:

56.13.1 Wastewater composition;

56.13.2 Method, manner, and frequency of wastewater treatment;

56.13.3 Wastewater pretreatment requirements;

56.13.4 Physical, chemical, and biological characteristics of a land application facility; and

56.13.5 Any other condition the Department finds necessary to protect public health or environment.

56.14 Compliance Schedules The Department may establish a compliance schedule for existing facilities as part of the permit conditions including:

56.14.1 Specific steps or actions to be taken by the permittee to achieve compliance with applicable requirements or final permit conditions;

56.14.2 Dates by which those steps or actions are to be taken; and

56.14.3 In any case where the period of time for compliance exceeds one (1) year the schedule may also establish interim requirements and the dates for their achievements.

56.15 Monitoring Requirements.Any facility may be subject to monitoring requirements including, but not limited to:

56.15.1 The installation, use, and maintenance of monitoring equipment;

56.15.2 Monitoring or sampling methodology, frequency, and locations;

56.15.3 Monitored substances or parameters;

56.15.4 Testing and analytical procedures; and

56.15.5 Reporting requirements including both frequency and form

56.16 Permit Modification

56.16.1 Minor Modifications.Minor modifications are those which if granted would not result in any increased impact or risk to the environment or to the public health. Such modifications shall be made by the Department. Minor modifications are normally limited to:

56.16.1.1 The correction of typographical errors.

56.16.1.2 Transfer of ownership or operational control.

56.16.1.3 A change in monitoring or reporting frequency.

56.17 Major Modifications. All modifications not considered minor shall be considered major modifications. The procedure for making major modifications shall be the same as that used for a new permit under these regulations.

56.18 Permit Transferable. Permits shall be transferable to a new owner or operator provided that the permittee notifies the Department by requesting a minor modification of the permit before the date of transfer and that such transfer is consistent with any trust indenture required by these rules.

58.19 Appeals of final permits shall be governed by 7 Del.C., 6008 and 6009.

58.20 Permit Revocation

58.20.1 Conditions for Revocation.The Department may revoke a permit if the permittee violates any permit condition or these regulations.

58.20.2 Notice of Revocation.Except in cases of emergency, the Department shall issue a written notice of intent to revoke to the permittee prior to final revocation. Revocation shall become final within twenty (20) days of receipt of the notice by the permittee, unless within that time the permittee requests an administrative hearing in writing.

58.20.3 Notice of Hearing.The Department shall notify the permittee in writing of any revocation hearing at least twenty (20) days prior to the date set for such hearing. The hearing shall be conducted in accordance with 7 Del.C., Chapter 60.

58.20.4 Emergency Action. If the Department finds the public health, safety or welfare requires emergency action, the Department shall incorporate findings in support of such action in a written notice of emergency revocation issued to the permittee. Emergency revocation shall be effective upon receipt by the permittee. Thereafter, if requested by the permittee in writing, the Department shall provide the permittee a revocation hearing and prior notice thereof.

Such hearings shall be conducted in accordance with 7 Del.C., Chapter 60.

58.21 Plan of Operation and Management

An outline for the scope of the Plan of Operation and Management required for the Department Land Treatment System Permit is presented in Subsection 701. The Plan is submitted by the owner or owner's engineer. Once accepted by the Department, this Plan becomes the operating and management manual for the facility.

58.22 Land Treatment Systems with Underdrains

Land treatment systems incorporating drainage improvements in the system design that result in a point discharge to surface waters fall under Federal and State point source discharge rules and regulations. These systems will be issued a National Pollutant Discharge Elimination System (NPDES) Permit in place of a Delaware LTS Permit. The NPDES Permit will include a special condition requiring submission and approval of a Plan of Operation and Management as required for the Delaware LTS Permit. All procedures for State review and approval outlined in this chapter remain in effect for underdrained land treatment systems.

59.0 Engineering Plans and Specifications

59.1 Review

59.1.1 In order to obtain Department acceptance of the Design Development Report and issuance of a final Land Treatment System (LTS) Permit (reference Section 14.0), the owner must submit detailed construction plans and specifications. These should be completed in accordance with the rules and current policies of the Department. The plans and specifications will be reviewed for consistency with the Design Development Report and accepted engineering standards. Upon satisfactory review of the plans and specifications, a letter authorizing construction will be written. This approval is valid for two years. If construction has not begun within this period, the project will require reevaluation. Approval of privately owned, domestic wastewater irrigation systems is contingent upon execution of the trust indenture referenced in subsection 12.1.

59.2 Final Inspection

59.2.1 Upon project completion, the design engineer or owner must certify, in writing and through submission of "as-builts", to the Department that the project was constructed in accordance with the approved plans and specifications. Upon receipt of this certification, a Department representative will inspect the completed facility. When the facility is verified as being complete and operational, a letter authorizing operation under the facility's LTS Permit will be issued. Upon granting written approval for operation, the Department shall give notice of such approval to any person who has submitted a written request for such notice.

60.0 Table 202-1 Design Development Report Information

60.1

60.1.1 Site Description:

60.1.2 Location map

60.1.3 Climate

60.1.4 Geology (including subsurface hydrology)

60.1.5 Topography

60.1.6 Access

60.1.7 Wells within 2500 L.F. of facility

60.1.8 Groundwater quality background data

60.2 Scaled drawing with 2-foot elevation contours showing the preliminary site layout including:

60.2.1 Preapplication treatment facility

60.2.2 Storage pond(s)

60.2.3 Spray fields

60.2.4 Buffer zones

60.2.5 Soil investigation locations

60.2.6 Access roads and utilities

60.2.7 Watercourses

60.2.8 Monitor well locations

60.2.9 Drainage structures

60.2.10 Flood elevations

60.2.11 Residences and habitable structures within or contiguous to the site

60.3 Design wastewater characteristics, influent to preapplication treatment facility and treated effluent to spray fields (specific industrial-type wastewaters and some vegetation management schemes may require different or additional characterization):

60.3.1 Average and peak daily flows

60.3.2 Biochemical Oxygen Demand (for preapplication facility management)

60.3.3 Chemical Oxygen Demand (for land treatment system management)*

60.3.4 Total Organic Carbon

60.3.5 Total Suspended Solids

60.3.6 Ammonia, Total Kjeldahl and Nitrate and Nitrite Nitrogen

60.3.7 Total Phosphorus

60.3.8 Chloride

60.3.9 Sodium Adsorption Ratio (when appropriate)

60.3.10 Electrical Conductivity

60.3.11 Metals

60.3.12 Priority Pollutants**

60.3.13 pH

60.4 Detailed Soil Investigation Report (reference Table 202-2).

60.5 Water Balance/determination of design wastewater loading(s).

60.6 Nitrogen Balance/selection of cover crop and management scheme.

60.7 Phosphorus and other constituent loading rates 60.8 Determination of land limiting constituent (LLC).

60.9 Determination of wetted field area(s) and required storage volume.

60.10 Process design for preapplication treatment facility.

60.10.1 Schematic of pump stations and unit processes

60.10.2 Basin volumes, loading rates, hydraulic detention times, storage capacities, etc.

60.10.3 Capacity of pumps, blowers and other mechanical equipment

60.11 Groundwater and Effluent Monitoring Plan

60.12 Proposed trust indenture for Department approval (for private domestic wastewater irrigation systems)

60.13 *Chemical Oxygen Demand or Total Organic Carbon may be substituted for industrial wastewaters where appropriate.

60.14 **Priority pollutant analysis is required for all industrial wastewaters and municipal wastewater systems that receive industrial process wastes. The analyses required depend on the particular process wastewater being discharged and will be determined on a case-by-case basis. However, in all cases the presence of industrial process wastewaters must be identified. A current listing of the 126 priority pollutants can be found by referencing 40 CFR Part 423, Appendix A, 1987.

60.15 All design calculations must be submitted. Details and an example of the determination of needed land area and site life are given in the Guidance Section for Slow Rate Land Treatment and in Subsection 703, Example Calculations.

THIS TABLE IS NOT AN EXHAUSTIVE LISTING OF ALL REQUIREMENTS FOR OBTAINING A SPRAY IRRIGATION PERMIT. PLEASE REVIEW ALL PARTS OF THESE REGULATIONS PRIOR TO SUBMISSION OF A DDR.

61.0 Table 202-2 Detailed Soil Investigation Report Information

61.1

61.1.1 Site description:

61.1.2 Location map

61.1.3 Topographic map

61.1.4 Soil Survey map

61.1.5 Site soil investigations

61.2 Soil series descriptions (each soil series present).

61.2.1 Texture

61.2.2 Permeability

61.2.3 Slope

61.2.4 Drainage

61.2.5 Depth to seasonal high water table

61.2.6 Depth to bedrock

61.2.7 Erodibility

61.3 Soil characteristics (each soil series present):

61.3.1 Soil investigations:

61.3.1.1 Soil horizons

61.3.1.2 Depth to groundwater

61.3.1.3 Depth to impermeable strata

61.3.2 Unified Soil Classification

61.3.3 Saturated hydraulic conductivity (restrictive horizons)

61.3.4 Soil chemistry:

61.3.4.1 pH

61.3.4.2 Cation exchange capacity

61.3.4.3 Percent base saturation

61.3.4.4 Phosphorus adsorption

61.3.4.5 Nutrients (N,P,K)

61.3.4.6 Characterization of metals and minerals

61.3.5 Engineering properties of soils proposed for pond construction

61.4 Identification of subsurface conditions adversely affecting vertical or lateral drainage of the land treatment site.

61.5 Delineation of soils and areas suitable and not suitable for wastewater irrigation.

61.6 Determination of design percolation.


62.0 Required Design Considerations

62.1 Suitability of Sites for Wastewater Irrigation

62.1.1 Location

62.1.1.1 There are two, often contradictory, requirements for slow rate land treatment sites: proximity to the wastewater source and a large tract of suitable land. Additional considerations are a moderate degree of isolation, ease of access, availability of utilities and protection from flooding. Wastewater irrigation systems can be developed on agricultural land and forests. The Department will also consider wastewater irrigation of golf courses, cemeteries, green areas and parks. Special preapplication treatment requirements may apply to such systems (see subsection 64.7.2.2 and 64.7.2.3).

62.2 Topography

62.2.1 Due to equipment limitations and erosion potential, maximum slopes for wastewater spray fields are generally limited to 7 percent for row crops, 15 percent for forage crops and 30 percent for forests. Sloping sites are preferred over flat sites because lateral subsurface drainage occurs which makes ponding and extended saturation of the soil less likely. Depressions must be carefully evaluated in the design.

62.3 Soils

62.3.1 In general, soils with a USDA Soil Conservation Service permeability classification of moderately slow (.02 to 0.6 inches/hour) or more are suitable for wastewater irrigation. However, groundwater and drainage conditions must also be suitable. Soils which are poorly drained, have high groundwater tables or restrictive subsurface soil layers are generally not suitable for slow rate treatment without drainage improvements.

62.4 Hydrogeology

62.4.1 Hydrogeologic characteristics of the site shall be investigated by a Professional Geologist registered in the State of Delaware and submitted as part of the design report. This information can be obtained from published literature or from on-site field investigations. The hydrogeologic report shall contain a description of the geologic and hydrogeologic characteristics of the site including:

62.4.1.1 Stratigraphy;

62.4.1.2 Lithology of the water table aquifer;

62.4.1.3 Hydrologic properties of the water table aquifer, including horizontal and vertical hydraulic conductivity, groundwater flow gradient, water table elevations, and a determination of the depth to seasonal high groundwater table including an estimate of seasonal variations;

62.4.1.4 Elevation interval and lithology of the uppermost, laterally extensive confining unit;

62.4.1.5 Lithology, elevation interval and hydrologic properties of the uppermost confined aquifer;

62.4.1.6 Identification of any facilities, such as nearby high capacity irrigation wells, that do or may potentially influence groundwater flow characteristics;

62.4.1.7 An assessment of the effects on groundwater flow at the land treatment site, if any, that may be caused by nearby activities;

62.4.1.8 Identification of any activities adjacent to the land treatment site which do or may potentially contaminate groundwater at the land treatment site, and a description of such activities and associated potential contaminants.

63.0 Soil Investigations

63.1 General

63.1.1 Each design development report shall include a detailed soils investigation report which contains details on the field investigations conducted by a person who is registered as a Professional Soil Scientist with the American Registry of Certified Professionals in Agronomy, Crops and Soils (ARCPACS) depicting soils conditions on the site. Soil investigations for land treatment differ greatly from investigations for foundations, road and other civil engineering works. As a result, different investigative and testing methods are required. The land treatment soil investigation must characterize the permeability and chemical properties of the surface 5 to 10 feet of the soil profile. It must verify Soil Conservation Service soil mapping. It must also determine the elevation of the seasonal high groundwater, establish the groundwater flow direction and gradient, and identify any subsurface conditions which may limit the vertical or lateral drainage of the land treatment site. The number of soil samples necessary to supply all of this information will be dependent on the nature of the particular site. As a minimum however, the Department requires that at least one sample be taken for every 5 to 10 acres of each soil series to confirm the Soil Conservation Service mapping and to provide a sufficient number of undisturbed soil samples. The specific information required for design is outlined in Table 202-2.

63.2 Saturated Hydraulic Conductivity Testing

63.2.1 Saturated vertical hydraulic conductivity testing is required for the most limiting horizon (i.e., horizon with lowest saturated conductivity) of each major soil series present. The most limiting soil horizon shall be determined from soil survey information and on-site observations. A minimum of three (3) tests for each major soil series shall be performed. These test results will be compared with the values published by SCS. If the values are not comparable, additional testing is recommended. Testing for saturated horizontal hydraulic conductivity may be necessary when subsurface drainage systems are planned or when lateral subsurface drainage is the predominant drainage mechanism for the land treatment site. Less intensive conductivity testing may be conducted when hydraulic loading is much less than site capacity.

63.2.2 Acceptable methods for saturated hydraulic conductivity testing are listed in Table 302-1. Field testing is preferred over laboratory testing methods. The Department will accept laboratory approaches only when field testing is not possible. Percolation tests as performed for septic tank drain fields are not acceptable.

63.2.3 Use of the hydraulic conductivity values to determine design percolation rates is discussed in Section 3.0.

63.3 Soil Chemical Testing.

63.3.1 The pH, cation exchange capacity, phosphorus adsorption and percent base saturation, of each soil series must be determined from samples taken from the A and B horizons. These chemical tests determine the retention of wastewater constituents in the soil and the suitability of the soil for different cover crops. A minimum of three (3) samples for each major soil series shall be taken. Testing for soil nutrients (nitrogen, phosphorus and potassium) and agronomic trace elements shall be included if appropriate for the vegetative management scheme.

63.3.2 Soil chemical testing should be in accordance with Methods of Soil Analysis published by the American Society of Agronomy, Madison, Wisconsin. Other methods, properly documented, may be accepted upon approval by the Department.


64.0 Table 302-1 Hydraulic Conductivity Test Methods

64.1 Saturated Vertical Hydraulic Conductivitya

64.1.1 Laboratory Testsb:

Constant Head Method

ASTM D 2434-68

(coarse grained soils)

AASTHOT 215-70

 

Bowles (1978), pp 97-104

 

Kezdi (1980), pp 96-102

Falling Head Method

Bowles (1978),pp 105-110

(cohesive soils)

Kezdi (1980), pp 102-108

64.1.2 Field Tests:

Cylinder Infiltrometer

Boersma (1965)

 

U.S. EPA (1981),pp 3-17 to 19

Double Tube Method

Bower (1966)

 

U.S. EPA (1981), pp 3-24 to 3-27

Air-Entry Permeameter

Bower (1966)

Method

Reed and Crites (1984), pp 176-180
Topp and Binns (1976)
U.S. EPA (1981), pp 3-24 to 3-27

64.2 Saturated Horizontal Hyraulic Conductivityd S

64.2.1 Field Tests:



Auger Hole Methodc

Reed and Crites (1984), pp 165 to 168

 

U.S. EPA (1984), pp 3-31 to 35

 

 

Slug Test

Bouwer and Rice (1976)

64.3 aOther methods, properly documented, may be accepted by the Department. However, "standard" percolation tests as performed for septic tank drain fields are not acceptable. Basin flooding tests are appropriate only to design of rapid infiltration systems.

64.4 bThese tests require undisturbed" field samples properly prepared to insure saturation. Reconstructed field samples are not acceptable. A description of the field sampling technique should accompany the laboratory testing results.

64.5 cMethods recommended by the Department.

64.6 dTesting for saturated horizontal hydraulic conductivity is required at land treatment sites where drainage improvements are planned and where lateral, as opposed to vertical subsurface drainage, is the predominant drainage pathway.

64.7 Preapplication Treatment Requirements

64.7.1 General

64.7.1.1 Wastewater irrigation systems have a demonstrated ability to treat high strength organic wastes to low levels. However, such systems require management with particular attention paid to organic loading rates and aeration of the soil profile between wastewater applications.

64.7.1.1.1 The Department requires that all wastewaters containing domestic wastes receive biological treatment prior to irrigation. This is necessary to:

64.7.1.1.2 Protect the health of persons contacting the irrigated wastewater, and

64.7.1.1.3 Reduce the potential for odors in storage and irrigation.

64.7.1.1.4 Most industrial wastes will require some pretreatment but some may be suitable for direct land treatment by irrigation. The Department will evaluate such systems on a case-by-case basis. All industrial system Design Development Reports must contain copies of work place chemical lists. This information will aid the Department and the applicant in evaluating potential problems with a land treatment system. The principal criteria to be considered by the Department to not require pretreatment will be a demonstration that odors and nuisance conditions and adverse impacts to groundwater or soil such as clogging and runoff, will not occur.

64.7.2 Wastewater Reclamation Standards for domestic and municipal wastewater for BOD, TSS, and Disinfection, Based on Site Access Control.

64.7.2.1 The primary water quality objective for any reclaimed wastewater spray irrigation project is to prevent the spread of waterborne diseases while also preventing environmental degradation of the site and surrounding areas. Protection of public health can be achieved either by limiting public access to the site or by reducing the concentration of pathogenic bacteria and enteric viruses in the reclaimed wastewater. In cases where public access cannot be restricted, such as landscaped areas, golf courses, parks, and roadway medians, levels of wastewater pretreatment need to be increased in order to assure comparable public health safeguards exist. Epidemiological studies performed at domestic wastewater spray irrigation reclamation sites have shown that reclaimed wastewater treated to advanced levels with reduction of entritic viruses below detectable levels pose no ascertainable risks to public health. Based on these findings, the Department has established the following pretreatment requirements based on the level of site access control to be provided.

64.7.2.1.1 Restricted Public Access Sites (See subsection 73.2)


64.7.2.1.1.1 Restricted public access sites are sites where access to the site by the public is controlled and only accessible to authorized operators and farm personnel. All wastewater must be treated to a 5-day biochemical oxygen demand of 50 mg/L at average design flow and 75 mg/L under peak loads. Total suspended solids are limited to 50 mg/L for mechanical systems and 90 mg/L for ponds. Disinfection is required to yield a discharge not to exceed 200 colonies/100 mL fecal coliform at all times. Disinfection requirements may be waived when wastewater is irrigated in remote or restricted use sites such as forests.

64.7.2.2 Limited Public Access Sites

64.7.2.2.1 Limited public access sites are landscaped areas where public access is limited to specific periods of time and buffer zones pursuant to subsection 311 can be maintained to property boundaries and surface waters. Spray irrigation activities shall be limited to those periods of time when the public is effectively excluded from accessing the site. All wastewater irrigated on limited access sites must not exceed a 5-day biochemical oxygen demand of 30 mg/L. Total suspended solids are limited to 30 mg/L. Disinfection to reduce fecal coliform bacteria to 200 colonies/100 mL is required.

64.7.2.3 Unlimited Public Access Sites

64.7.2.3.1 Unlimited public access sites are those landscaped areas such as golf courses, residential lawns, cemeteries, parks, and highway medians which may not have adequate buffer zones and which are accessible to the public at all times. An example is the typical residential golf course community where private homes abut the fairways and greens, and the public cannot effectively be excluded from accessing the site during spray irrigation.All wastewaters used for irrigation of unlimited access sites must be pretreated to advanced limits with high- level disinfection. The advanced treatment system shall include the following processes: oxidation,clarification, coagulation, flocculation, filtration, and disinfection.The wastewater shall not contain more than ten (10(c) mg/L total suspended solids, and turbidity shall not exceed five (5(c) TU. 5-day biochemical oxygen demand shall not exceed ten (10(c) mg/L, and the wastewater must be disinfected to reduce fecal coliforms to a level below 20 colonies/100 mL.

64.7.3 Nitrogen

64.7.3.1 Maximum nitrogen removal occurs when nitrogen is land applied in the ammonia or organic form. Nitrate is not retained by the soil and leaches to the groundwater, especially during periods of dormant plant growth. Therefore, the preapplication treatment system should not produce a nitrified effluent.

64.7.3.2 The Department recommends that aerated or facultative wastewater stabilization ponds be used for preapplication treatment where possible. These systems generally produce a low-nitrate effluent well suited for wastewater irrigation. When mechanical plants are employed for preapplication treatment, they should be designed and operated to limit nitrification.

64.7.3.3 The Design Development Report shall indicate the expected range of nitrogen removal in the preapplication treatment system. Predictive equations for nitrogen removal in facultative wastewater stabilization ponds have been developed by Pano and Middlebrooks (1982), and Reed (1985).

64.7.4 Pretreatment Systems and Storage Ponds

64.7.4.1 Pretreatment may consist of mechanical or pond-type systems. All systems must have provisions for storage either as a separate facility or incorporated into the pretreatment system if the efficiency of treatment is not compromised. Pretreatment ponds may be aerated, facultative or a combined aerated/facultative system. The storage pond and the irrigation pump station must be designed such that pumping does not affect the design hydraulic detention time. The Department recommends the United States Environmental Protection Agency's October 1983 Design Manual: Municipal Wastewater Stabilization Ponds as a reference for design of preapplication treatment ponds.

64.7.4.2 Ponds used for preapplication treatment and storage must have impermeable liners. Facultative pond cells should have an appropriate length to width ratio consistent with current practice to minimize short circuiting with a depth between 3 and 5 feet. Sizing of completely and partially mixed aerated ponds should be based on first-order removal rate kinetic equations and the expected annual temperature variation. Adequate freeboard is required for all ponds to contain excess rainfall and wastewater flows.

64.7.4.3 Treatment facilities for wastewater to be used on unlimited access sites shall include continuous on-line monitoring for turbidity before application of the disinfectant. Continuous on-line monitoring of residual disinfection concentrations, shall be provided at the compliance monitoring point for limited and unlimited access sites. The permittee shall develop and submit for the Department's review and approval, an operating protocol designed to insure that the high-level disinfection criteria will be met before the wastewater is released to the storage impoundment system or to the wastewater reuse system. Automatic diversion of wastewater that fails to meet the operating criteria shall be established in the operating protocol. Such diversions shall be to a reject wastewater storage system. Increased reject wastewater storage capacity shall be provided if needed.

64.7.4.4 Reclaimed wastewater that fails to meet the criteria established in the operating protocol shall not be discharged into the storage impoundment system or to the reuse system. Such substandard wastewater (reject wastewater) shall be either stored in a separate off-line system for subsequent additional treatment, or shall be discharged to another permitted reuse system requiring lower levels of pretreatment, or to a permitted effluent disposal system.


65.0 Soil and Cover Crop Compatibility

Inorganic constituents of effluent from preapplication treatment must be compared with Table 303-1 to insure compatibility with land treatment site soils and cover crops. IN NO CASE SHALL THE CUMULATIVE METAL LOADINGS EXCEED THE LEVELS SET FORTH IN TABLE 2 OF THE GUIDANCE. THE APPLICANT SHALL UTILIZE TABLE 2 IN CONJUNCTION WITH TABLE 303-1 TO CALCULATE THE SITE LIVES FOR THE CONSTITUENT METALS(r)


66.0 Protection of Irrigation Equipment

Prior to pumping to the spray field distribution system, consideration must be given to removal of materials which might clog distribution pipes or spray nozzles. Screening to remove solids greater than one-third (1/3(c) the diameter of the smallest sprinkler nozzle is recommended by some sprinkler manufacturers. If screens are necessary, screenings should be captured and removed for disposal (method of disposal must be described in detail in DDR).


67.0 Determination of Design Percolation Rates

67.1 General

67.1.1 An important step in the design of a slow rate land treatment system is development of a "design percolation rate" from results of the site hydraulic conductivity evaluations. This value is used in water balance calculations to determine design wastewater loading(s(c) and thus spray field area requirements. The percolation rate is a function of soil permeability and site drainage.

67.2 Design Values

67.2.1 The restrictive saturated hydraulic conductivity of each soil series must be identified. Any subsurface conditions which limit the vertical or lateral drainage of the soil profile must also be identified. Examples of such conditions are shallow impermeable strata, high water table and extremely anisotropic soil permeability. Values of saturated vertical hydraulic conductivity from soil testing are used to develop the design percolation rate.



68.0 Table 303-1 Assessment Criteria For Inorganic Constituents in WasteWater Applied to Land (U.S. EPA, 1976 and 1981)

68.1

Potential Problem
and Constituent

No Problem

Increasing Problem

Severe

pH (std. units)

5.5 - 8.4

 

12

Bicarbonate (meq/L)
(mg/L as CaCO3)

1.5
< 150

1.5-8.5
150-850

>8.54
> 850

Chloride (meq/L)
(mg/L)

< 3.0
< 100

> 3.0
> 100

> 10
> 350

Fluoride (mg/L)

< 1.8

 

 

Ammonia (mg/L as N)

> 5.0

5.0 - 30

> 30

Sodium (meq/L)
(mg/L)

70

9.0
210

Trace Metals (mg/L):

 

 

 

Aluinum