For many years communities developed storm sewer systems for purposes of removing storm flows. Excessive storm flows hampered commerce and commerce could be facilitated with removal of stormwater. These storm sewers were not intended as waste collection structures, but they soon began to serve as a conveyance for human wastes from the community to surface waters which carried the pollutants downstream and often into the public water system. The now famous epidemiological study of the water companies serving the City of London by Dr. John Snow resulted in an elegant solution to a severe public health problem: Remove the handle and eliminate the source.

Little has changed since these early references. The land and the water continue to serve as the primary receivers for waste. The emphasis, however, has changed from merely a disposal philosophy to a more comprehensive treatment and beneficial reuse philosophy. Today the land remains a receiver for waste, but the waste is applied at rates that are assumed beneficial. Waterways remain a receiver for treated wastewater, but the pollutant loads in the wastewater discharged have been reduced significantly through sophisticated treatment processes.

Following World War II the GI Bill promoted home ownership for all veterans. The construction and home finance industries responded. Unfortunately, the wastewater management infrastructure was unprepared for this housing boom. Homes were developed in cities or communities with very rudimentary wastewater management facilities, often primary settling was the only treatment provided prior to discharge. Alternatively, many homes were developed with onsite septic systems to treat wastewater. These were considered short-term solutions intended to serve the dwelling only until sewer lines were extended - in many instances sewer lines were never extended. These deplorable conditions led to serious problems where poorly functioning municipal discharge systems and numerous failed onsite systems threatened both public health and environmental quality. In 1966 the Congress of the U.S. passed the first Clean Water Act which transferred many of the powers of the Public health Service to a newly created environmental agency, the EPA, and established PL 660 funding for wastewater systems. This law set aside some funds specifically for wastewater treatment system design and construction. This program was very successful and in 1972, Congress passed PL 92-500, the Clean Water Amendments. This act provided funding to communities for the design and construction of wastewater management systems, established the innovative and alternative wastewater management program, and provided funding for experimentation and innovation in wastewater treatment.

With passage of Public Law 92-500 the Environmental Protection Agency was strengthened and this established a major change in the philosophy of wastewater management. This law encouraged the development of wastewater management systems that discharged biologically treated wastewater and established a target treatment level or standard of 30mg/1 BOD and 30mg/1 solids or 85% removal. These levels are considered to be secondary treatment. The law also encouraged the discharge of wastewater onto land for beneficial reuse. Projects that could demonstrate the elimination of direct discharge of pollutants to surface waters were actually awarded higher levels of funding than systems that continued to discharge.

Two categories of land based systems were encouraged by PL 92-500; individual onsite systems that relied on the land for treatment and community based systems such as the system for the Towns of Westboro, WI, which developed a community mound system and Edenton or Garner which developed wastewater irrigation facilities to apply treated wastewater onto land and produce both a hay crop and a tree crop. Many municipal wastewater irrigation systems are operating successfully throughout North Carolina and the remainder of the country. Onsite systems too have evolved since passage of PL 92-500 and today sophisticated onsite systems are permitted to address problems such as small lot sizes, shallow watertable, slowly permeable soils, complex topography or steep slopes. The material which follows is intended to demonstrate several of the options available for managing domestic, commercial, industrial, or municipal wastewater through the use of non-traditional options. Let us take a tour of the variety of onsite and small community systems operated throughout North Carolina and for which a comprehensive management system is essential.

Initially the onsite system was an outhouse and many are still in existence today. Straight pipe systems which discharge settled effluent are still in use today in many parts of the country. These systems are not considered as either environmentally sound or protective of public health and there is a concerted, nationwide effort to eliminate substandard onsite wastewater treatment systems. Options used today include: conventional gravity dosed systems, shallow placed systems, pressure dosed surface or subsurface systems, and advanced pretreatment systems such as media filters or aerobic treatment units often with disinfection preceding the soil or land based component of systems. In some instances, advanced treatment will permit individual discharges from these onsite systems to aquatic receiver systems.

Land based onsite systems can be characterized by the type of dosing involved. Traditionally, onsite systems utilized gravity to create the hydraulic gradient along which liquids moved. Today effluent pumping is accomplished with ease and reliability using low cost effluent pumps and controls. Effluent pumps and controls have opened a wide range of alternative onsite wastewater management systems to widespread use throughout the country. These pressure dosed systems provide system designers additional options to address a variety of problem site or soil conditions.

Gravity dosed systems remain the option of choice where site and soil conditions permit installation. These systems are typically placed in wide trenches excavated to a depth of between two and three feet and constructed on contour. Variations to the conventional trench include chamber systems, large diameter pipe systems, porous block systems, and expanded polystyrene trench systems (EEE ZZZ Lay). Soil loading rates for these systems are determined by soil texture. Systems designed foe sandy soils can be developed to apply liquid at rates of up to 1.2 gallons per square foot per day. Systems developed on clayey soils may be designed with a hydraulic loading of 0.1 gallons per square foot per day. Each of these systems requires a replacement area. The footprint for the trench component of a conventional system serving a single family home with a flow of 360 gallons per day will cover a land area calculated for specific soil textures as:

Sand: 360 GPD/1.2GPF2PD=300Ft₂ (600 total with repair); footprint, 1600Ft2
Loam: 360 GPD/0.5GPF2PD=720Ft₂ (1440 total with repair); footprint, 3360Ft2
Clay: 360 GPD/0.1GPF2PD=3600Ft₂ (7200 total with repair); footprint, 10,000Ft2

The required area must be available in order to develop a gravity dosed system on a single family homesite, the area can be onsite or off-site provided the land area is specified for the designated home or dwelling.

Where conventional gravity dosing can not be used, pressure dosing may be an option provided the receiver site meets the specifications established in North Carolina Administrative Code (NCAC) or other applicable code for host state for specific types of systems. Generally pressure dosed systems are designed at loading rates approximately one half of those used for comparable textures and gravity dosing. A sandy soil might be developed at a loading rate of 0.6 GPF2PD, but the entire area of the pressure dosed field is used as the receiver area. Footprints for conventional and pressure dosed fields are approximately the same for each textural class of soil.

Pressure dosed systems are now permitted through an operations permit and an annual inspection is required to assure that the system is operation properly. The operation and maintenance requirements for these sophisticated or mechanical onsite systems will help to assure the long term and successful operation of these alternatives. The tanks, pumps, controls and receiver fields are all inspected as a part of this annual inspection.

The variety of pressure dosed subsurface systems permitted in North Carolina include Low Pressure Pipe (LPP) systems, Pressure Dosed Mound Systems, and subsurface drip disposal systems. The mound system is used where the seasonal saturation is present at depths of between 12 and 18 inches. The drip systems are used where seasonal saturation is present at 12 to 18 inches and where site conditions will not permit installation of other alternatives. One distinctive feature of pressure dosed drip systems is very shallow placement of the drip tubing. The effluent to be treated is placed at very shallow depths and in the root zone of plant material established on the receiver site.

The monitoring data collected to date indicates that a very significant percentage of the plant nutrients contained in the wastewater are assimilated into plant material. This helps protect the quality of shallow groundwater. Results of groundwater monitoring associated with several drip disposal alternatives operating in North Carolina are presented in Table 1. In addition, the results of plant tissue testing accomplished on a drip disposal site and a control site are presented in table 2, Plant Tissue Quality Associated With Shallow Placed Drip Effluent Treatment Site and Irrigated Control, attached.

All onsite systems will produce septage. This is the semi-solid, partially digested organic material which is retained in the tank. Septic tanks MUST be pumped at least every 5 to 8 years and the septage or residuals retained in these tanks MUST be handled appropriately. All septage treated must be managed in accordance with provisions established by rule (40 CFR Pt. 503).

All of the sophistication incorporated into the design, installation and ultimately the operation of these onsite systems requires well trained operators. Several states including Texas, Washington, and North Carolina are now requiring trained and certified service providers and operators for many of the onsite options available today. The management requirements for onsite systems operated in North Carolina are summarized in figure 1, attached.

The USEPA recognizes that these onsite and decentralized systems are consistent with sound public health and environmental protection. Today the USEPA is in the process of rewriting the Design Manual for Onsite Systems and in also developing a Management Standards Manual for decentralized wastewater management systems. This management standards manual is viewed as essential to assure that the systems are maintained and managed properly. The manual will be discussed below.

In April 1997, U.S. Environmental Protection Agency (EPA) released its Response to Congress on Use of Decentralized Wastewater Treatment Systems. The purpose of the report was to analyze the costs and benefits of onsite/decentralized wastewater treatment systems as alternatives to conventional sewerage and EPA's plans for implementing the alternatives. The report identified several significant barriers to their implementation, one of which is the lack of effective local onsite system management programs. Subsequently, EPA and U.S. Department of Agriculture (USDA) included in its Clean Water Action Plan: Restoring and Protecting America's Waters, published in 1998, a commitment to establish a set of voluntary standards for management of onsite/decentralized wastewater treatment systems and facilities. The model management standards are to be presented in a manual scheduled for publication in 2000. The manual is intended to provide local government entities and state/tribal environmental or health agencies with guidance on establishing comprehensive, yet appropriate, onsite/decentralized management programs as a part of a sustainable wastewater management infrastructure. The remainder of this paper describes the conceptual plan for addressing the model management standards.

APPROACH

Management models can vary depending on a number of factors. These factors include the sensitivity of the receiving environment, the complexity of the treatment processes and/or equipment employed, and the capability of the local government entity's resources and administrative authority. More than one management model may be appropriate for a given set of conditions, but for each there are minimum requirements for administrative authority and functions of the management entity to ensure protection of human health and the environment.

Establishing a management program is a deliberate process. It involves public participation, defining, and instituting legal authorities, and the allocation and assignment of fiscal and human resources. Major changes in existing programs can be difficult. Some changes may require enabling legislation. It is often an easier process if the management program can grow as the needs for management increase. Therefore, a progressive series of model management standards will be described. As the sensitivity of the receiving environments and the complexity of the treatment process and/or equipment increase the authority and management functions of the management entity must increase commensurately. The level appropriate for the anticipated needs can be selected by the local government entity.

A comprehensive management program should contain the following elements:

1. System performance requirements to protect human health and the environment
2. System management to maintain performance within the established performance requirements
3. Compliance monitoring and enforcement to ensure system performance is achieved and maintained
4. Technical guidelines for site evaluation, design, construction, operation and acceptable prescriptive designs for specific site conditions and use
5. Education/training for service providers, regulators, planners, and owners
6. Certification/licensing for service providers and regulators to maintain standards of competence and conduct
7. Program audits to maintain the foundation of the management program on sound practices and procedures

System Performance Requirements: Onsite/decentralized treatment systems discharge treated wastewater to ground and/or surface waters. Because sensitivities of water resources to treated wastewater discharges vary, system performance requirements should reflect the specific characteristics of the receiving environment. Further, performance requirements should be specific and measurable to allow credible performance compliance monitoring of all systems. Therefore, the management program should include appropriate methodologies for determining appropriate water quality performance based on risk management procedures. Methodologies may include watershed models, sensitivity assessments such as DRASTIC, and other regional assessments. Where such assessment models are not available, simple site specific models could be used.

System Management: To maintain system performance within the established performance requirements, perpetual management is necessary. Management may be provided by the individual owner or through third party systems that may be private, quasi-public, public/private, or public. The type of management entity most appropriate is a function of the sensitivity of the receiving environment, treatment processes employed, and/or the management functions of the entity (Figure 1).

Compliance Monitoring and Enforcement: The local regulatory agency should have continuous oversight of the management of all onsite wastewater treatment systems. The system owner (the property owner, management district, or sanitary/utility district) is responsible for maintaining compliance. Renewable operating permits issued to the responsible party similar to National Pollutant Discharge Elimination System (NPDES) permits is an established method of maintaining the necessary oversight.

Technical Guidelines: Guidelines for site evaluation, design, construction, and operation are critical aids to owners and service providers to describe acceptable methods for achieving compliance with the established performance requirements. The guidelines should include prescriptive designs that may be used which are considered capable of meeting the performance requirements under specific site conditions and intended uses. At their option, owners also may submit alternative and/or innovative designs for approval provided the owner can reasonably show that the system can meet the performance requirements.

Education and Training: Education of the public, service providers, and regulators in standards of practice is an essential element of a management program.

Licensing/Certification: Service providers (site evaluators, designers, contractors, operators) and regulators should be licensed or certified to perform their duties. This is necessary to maintain high standards of competence and conduct. Continuing education should be required to maintain licensure or certification and they should be revocable if the holder is found to be negligent or fraudulent.

Program Audits: This model for rural infrastructure should be grounded in good science, engineering, and proper regulatory and management authorities and procedures. Periodic audits of the program should occur to identify appropriate research, enabling legislation, education, etc. necessary to achieve the goal of sustainable wastewater management infrastructure.

This community based management effort may allow the concurrent development of managed onsite systems to serve outlying areas in a community with the development of sub- community wide collection and treatment options to serve the remainder of a community or watershed. The service to the members of the community will be the same regardless of the type of wastewater system serving a facility. This issue of equity is critical if the onsite industry is to proceed and overcoming the public perception that an onsite system is somehow unsatisfactory treatment is a challenge for us all.

Both land based and stream discharge wastewater management systems have evolved tremendously over the last few years. Today, wastewater management systems are capable of operating as complex, biological nutrient removal facilities. Options range from onsite systems capable of achieving high levels of treatment to community based systems treating millions of gallons per day. The future of wastewater management will require reuse and recycling onto land as a part of any comprehensive program. The technology to treat, disinfect, monitor and maintain is there and competent, qualified operators are available and eager to serve.

Wastewater management constitutes one of the most significant of the challenges facing society. The challenge continues to stimulate scientists, engineers, elected and appointed officials nationwide. Cost effective solutions are available and the challenge to improve environmental quality will continue to stimulate us all. The recognition by the USEPA that there are a variety of options available will stimulate the development of a comprehensive management effort including all types and varieties of wastewater treatment.

System	Nitrate - N	Ammonium - N	Total P	Total N
Septic Drip (P)	4.9	2.8	<0.1	8.1
SF Drip (P)	3.8	<0.5	<0.1	5.2
Community Septic Drip (P)	3.2	0.8	<0.1	4.9

Table 1, Average Groundwater Quality Associated With A Drip Wastewater Treatment Systems Receiving Septic Tank Effluent or Sand Filtered Effluent Operating in the Piedmont of North Carolina (results as mg/l and sample locations are all 5 feet down gradient of installation)

Site	TN	NO3 - N	P	K	Dry matter
Drip	4.6	850 Mg/Kg	0.33	3.5	8.5 Tons/ac
Control	2.2	455 Mg/Kg	0.25	1.2	3.0 Tons/ac

Table 2, Plant Tissue Quality Associated With Shallow Placed Drip Effluent Treatment Site and Irrigated Control (Results as % for Chemical Constituents and Dry Matter unless specified)

This page created by Roland O. Coburn
Reasearch Tech I
on 3/23/00.
Last updated 7/27/00.