U.S Environmental Protection Agency Onsite Wastewater Treatment Systems Manual: A Performance Based Approach for Designing and Managing Onsite Wastewater Systems U.S Environmental Protection Agency

In the beginning . . . . And thou shalt have a Paddle upon thy Weapon, and it shall be: When thou wilt ease thyself abroad, Thou shalt dig therewith, and shalt Turn Back and Cover that which Cometh from Thee Deuteronomy 23:13

Where we’ve been . . .

2002 USEPA Onsite Manual Complements the 1980 Design Manual Promotes the use of design performance requirements Advocates perpetual management of all systems Focuses on risk- based assessments Available on the Internet and CD

How to access the OWTS Manual CDs are available at www.epa.gov/owm/onsite The online version is available at: http://www.epa.gov/ORD/NRMRL/ To order a printed version, send a request to: U.S. EPA/NSCEP P.O. Box 42419 Cincinnati, Ohio 45242-0419 Send an email to ncepimal@one.net or call 1-800-490-9198 or (513) 489-8190

Summary of manual contents Background and use of OWTSs Management of onsite systems System performance requirements Treatment processes and technologies Treatment system selection

Note: The Onsite Wastewater Treatment Systems Manual is not intended to determine appropriate or inappropriate uses of land. The manual presents information that can be used to select appropriate technologies and management strategies to minimize risks to human health and water resources in areas not connected to centralized sewage systems.

Background and use of OWTSs

Current shortcomings Lack of clear performance requirements Few O&M or management programs Watershed/regional impacts often ignored Poor public outreach and education Little coordination with planning, zoning, water resource, and other agencies and stakeholders

Reasons for concern Public health Water quality Property values Community quality-of-life

OWTS pollutants of concern

Nutrients and bacteria from a variety of sources are primary pollutants in the U.S. Onsite systems are a source of nutrients and bacteria

Onsite system malfunction rates U.S. Census Bureau Reports 7-10% National Small Flows Clearinghouse 10% Nelson, Dix, Shepard Survey up to 70% ??? Best professional judgement; failure definitions varied A significant number of community water systems list onsite systems as a potential contaminant source for drinking water supplies . . .

Buttermilk Bay Assessment

Increasing demand for groundwater POPULATION GROWTH 100% increase in public water withdrawals (1960 - 1995) Food production needs URBAN SPRAWL Concentrates demand Leads to reductions in ground water recharge ECOSYSTEM MAINTENANCE Water supplies are needed to maintain sensitive ecosystems and/or endangered species (e.g., Pacific NW, FL) 1. Agriculture (irrigation) represents the single largest source of demand for water; more than half the total ground water withdrawn annually.

Elevated nitrate concentrations in groundwater in Kent County, MI Nitrogen sources include agriculture and lawn fertilizers, atmospheric deposition, onsite systems Source: Kent County Health Dept.

Source Water Assessment & Protection Program (168,000 PWSs Must Have Complete Assessments By 2003) 2,156 (98%) 4,211 (96%) 1,347 (95%) 2,103 (98%) 2,023 (97%) 550 (96%) 8,352 (98%) 2,645 (96%) 1,628 (85%) 11,724 (99%) 10,630 (97%) 2,080 (98%) 718 (96%) 12,350 (98%) 479 (94%) 736 (97%) 10,389 (97%) 3,705 (98%) 1,932 (94%) 4,279 (95%) 1,329 (97%) 5,939 (95%) 675 (95%) 4,837 (96%) 5,801 (93%) 551 (97%) 953 (91%) 1,414 (94%) 2,101 (95%) 3,776 (96%) 3,815 (98%) 8,146 (91%) 1,079 (93%) 2,701 (94%) 712 (67%) 7,511 (97%) 1,173 (79%) 1,732 (93%) 1,527 (90%) 1,274 (95%) 1,199 (89%) 1,687 (94%) 1,645 (98%) 1,485 (88%) 702 (63%) 2,572 (92%) Puerto Rico 490 (74%) 1,820 (87%) 6,865 (89%) Required assessments in 50 States, Puerto Rico and D.C. are now underway. Goal is to achieve all assessments finished for 168,000 systems in 2003. That is daunting task. Only 9 states are 20% or more of the way there by 9/30/01, but all are currently scheduled to get there in 2003. Regions are reviewing how these assessments are progressing and how they are leading to local prevention efforts. Prevention is progressing in the states for some systems, particularly the larger public water systems, whether using ground water or surface water, because of their greater resources for watershed and wellhead protection activities. 141 (74%) 6,607 (94%) 1996 SDWA Source Water Assessments Source Water Protection 2003 1. Delineate Source Water area 5. Establish local SW protection risk management measures 2. Contamination source inventory 6. Develop Contingency Plans 3. Susceptibility Determinations 4. Public distribution & discussion of findings

Management of onsite systems Chapter 2 of the OWTS manual deals with system management The USEPA Office of Water has developed guidelines and a handbook for managing onsite and clustered systems

Management: traditional management focus . . . . Permitting: prescribed limits on acceptable sites; prescribed system designs Installation: oversight of construction and installers and/or licensing, registration O & M: homeowner booklets and brochures, tank pumping info Corrective actions: repair or replacement upon receipt of verified complaints

Performance-based management focus: Performance requirements based on relative risk to valued surface and ground water resources Management of all systems based on technology and risk assessments Simple systems installed at low densities farther away from valued resources = lower management intensity Complex systems or those installed at high densities near valued resources = managed more intensively

Performance-based management elements Cooperative watershed planning: specifying the necessary water quality to permit a specific use at a specific location downstream of the onsite treatment systems Performance-based design: requiring specific treatment levels Operation: renewable system permits, periodic inspections Maintenance: requiring tank pumping at regular intervals, maintenance contracts Corrective actions: replacement requires new performance-based designs

What constitutes a performance-based approach? Siting and design: Designing a system that meets performance requirements based on site conditions rather than requiring the site to meet prescriptive criteria (lot size, soil permeability, depth to groundwater, etc.) needed for the approved system type System management: Management programs that provide perpetual system oversight to protect public health, water resources, property values

Overview of performance-based approach Wastewater characterization Site evaluation Design boundary identification & characterization Regulatory requirements for system performance

Residential wastewater sources/flows

Residential wastewater characterization: flow and strength analyses Estimate: average daily flows (or use meter info) hourly and instantaneous peak flows wastewater strength (composition) using similar-facility comparisons or sampling info

Wastewater strength can vary considerably

Assessing site conditions Preliminary review Soil surveys, aerial photos, geology, slopes Info from adjacent systems, installers Reconnaissance survey Landscape position, vegetation, buildings, drainage, topography Identification of prospective sites

Assessing site conditions Consider broader planning needs Clustering of systems can improve performance, lower capital & O/M costs Detailed evaluation Soil profile analyses via backhoe pit Characterize subsurface wastewater flow path Groundwater assessment (redox, wells, maps, etc.)

Identify design boundaries ... places where conditions change abruptly… in subsurface infiltration systems, the soil is part of the treatment system. Infiltrative surface (biomat location) Restrictive horizons; perched water tables Surface of saturated zone (groundwater) Point at which performance must meet water quality goals (SW/GW discharge, point of re-use, spray irrigation, etc. as required by regs)

Common design boundaries

Close-up of trench system design boundaries

Identify desired performance requirements of regulatory agencies Assess cumulative ecosystem impacts TMDLs, 303(d) lists Source water protection (MCLs) Watershed restoration action strategies Anti-degradation requirements

Identify desired performance requirements (cont.) Protection of public health No surfacing or well pollution Protection of water resources Groundwater (pathogens, nitrate) Surface waters (pathogens, nutrients) Meet overall water quality standards Consider existing/planned system requirements and impacts System densities, critical areas Water resource sensitivities

Consider source water protection areas when establishing performance requirements Ground Water Surface Water 1. Source Water Protection includes prevention efforts for both ground waters and surface waters. 2. Source Water Assessments are delineating current sources of drinking water for all public water wells and surface water intakes in the country. 3. While these areas are clearly the highest priority geographic areas for protecting drinking waters currently used for public water, OW is also concerned about waters used by private water users, and with all potential drinking waters regardless of when they will become current sources.

Performance requirements should also consider watershed-scale impacts

Assess design boundary loadings Loadings to treatment system components controls sizing, technology selection Loadings to the infiltrative surface controls size of infiltration system Loadings to restrictive horizons controls vertical placement of SWIS Loadings to groundwater controls vertical placement, may limit type

Lateral view of an effluent plume showing its movement through the soil toward design boundaries

Typical treatment train components Septic tank(s) Single or multiple compartments Watertight; sized for peak flows Equipped with effluent screen to protect SWIS Subsurface wastewater distribution Trenches filled with gravel Gravelless trenches (chambers) Pressure-dosed systems Alternative systems

Treatment train components (cont.) Alternative systems Mounds, at-grades, intermittent or recirculating filters Aerobic units Vegetated submerged beds

Chapter 4 topics: processes & technologies Conventional OWTSs Soil based treatment and distribution systems Use of alternative and advanced pretreatment systems Fact sheets for classes of alternative treatment systems and special issues

Treatment processes: components of a conventional soil-based system

Desirable SWIS characteristics Width: < 3 ft. wide Length: Must meet contour load limits Orientation: Along landscape contours Vert. Placement: High in soil profile; 2 ft GW/BR Dosing: Uniform over infiltrative surface Landscape pos: Ridge lines, hilltop, shoulder slopes Drainage: Moderate- to well-drained site

Loadings

How well does soil treatment work? Very well . . . IF the topography, soil types, and groundwater levels meet requirements.

Dispersal system options: drip irrigation Drip lines high in the soil profile enhance treatment Can be used on sloping sites with trees, etc. Source: University of Minnesota Extension

Other Chapter 4 topics Aerobic treatment units (ATUs) Media filters (ISFs and RSFs) Fact sheets for about a dozen families/classes of available treatment units

Chapter 5: Treatment system selection New system design approach Rehabilitation of failed onsite system

Failure analysis: types of failure and effects

Failure analysis: onsite wastewater failure diagnosis and correction procedure

Failure analysis: onsite wastewater failure diagnosis and correction procedure (cont.)

Onsite manual relationship to clustered treatment systems Systems with capacity to serve 20 or more people per day defined as Class V Injection Wells under US EPA’s Underground Injection Control (UIC) Program Registration and groundwater protection States may have more stringent requirements Site evaluation issues Design issues Management issues

Cluster site evaluation Evaluation of ground water mounding potential Additional contour loading and performance boundary analysis Additional downstream flow and plume analysis

Cluster system design Multiple fields (totaling ~ 200% sizing) rotated into/out of service Greater need for uniform distribution (pressure or drip) Monitoring well requirements

Cluster system management Responsible management entity generally required Proactive inspection and monitoring program required Additional involvement in planning and oversight of residuals management, land use planning, and O & M programs

Status of EPA Alternative Sewers Manual EPA supplies are presently exhausted for hard copy distribution Manual can be viewed on web at www.epa.gov/ttbnrmrl/ by browsing publications and typing in 625/1-91/024

Cluster systems planning handbook is posted at http://www. ndwrcdp