Performance-Based (P-B) Regulation for Onsite/Decentralized Wastewater Treatment Systems A Vision for this Century

1. Performance-Based (P-B) Regulation for Onsite/Decentralized Wastewater Treatment SystemsA Vision for this Century . byEdwin K Swanson, PE

2. A Vision for a P-B Code Framework Wastewater Characteristics Model Onsite Wastewater Facility Function Environmental Receptor Models Soil Absorption Model Wastewater Dispersal Risk Models Aquifer Protection Waterbody/ WatershedProtection

3. Onsite Program Challenges • Affects suburban & rural property owners • Out-of-sight & out-of-mind owner attitude • Local programs often • are under funded • have limited private & public expertise • Industry is often a cottage industry with • local regulation & suppliers • resistance to change • Marketing considerations often drive decisions

4. Onsite Program Challenges(cont’d) • Prescriptive regulatory bias and lost linkages with the underlying science make it easier: . - to say “no” . - than to figure out an appropriate “yes” • Prescriptive regulation may be misused to constrain development rather than by zoning.

5. Minimum Elements of AnyOnsite Rule • Site evaluation (EPA #3) • System selection and design (EPA #4) • System installation (EPA # 5) • System operation & maintenance (EPA # 6) (EPA # is the Program Element Category in the Draft Voluntary Management Guidelines)

6. Properties of the P-B Vision • Provides for making decisions to apply onsite system technologies and practices that are supported by science, public acceptance & law • Raw wastewater is characterized for flow, constituents and strength to determine raw wastewater loading rates at facility inlet • System selection considers documented site conditions to determine limitations, if any, that require superior treatment & dispersal performance compared to a conventional septic system

7. Properties of the Vision (cont’d) • Site evaluation, soil properties, pollutant type & soil loading rate are considered when a soil treatment credit is approved in a zone of unsaturated flow beneath the dispersal works • Dispersal works design determined by soil properties, site evaluation and treated wastewater characteristics using algorithms for soil properties & pollutant loading rate

8. Properties of the Vision (cont’d) • Minimum performance for treatment & dispersal technologies is specified in terms of loading rate & statistical measures of pollutant reductions • Provides a scientific framework for making design adjustments based on raw wastewater, treatment performance & site conditions

9. P-B Code Elements • Siteinvestigation,systemselection,design & operation are integrated in a framework that ensures discharge performance • Discourages “gold plating” by requiring system selection to overcome site/soil limitations • Performance for treatment systems allow for evolving technologies • Technologies are consistently rated based on code-specific terms, documented performance & algorithms for integrating system design

10. P-B Code Elements (cont’d) • Operation based on a discharge permit, not a construction approval. Compliance is determined by conformance with the terms & conditions in a general permit rule • Compliance evaluation based on field observations, status of required operational records, and absence of unauthorized conditions • Owner is responsible for all servicing and availability of records

11. P-B Code Elements (cont’d) • Regulatory system inspection limited to • Complaint response and • Courtesy assistance • Mandatory comprehensive inspection when property changes ownership • Community-wide statistical verification study to • Evaluate system discharge performance and • Confirm code efficacy

12. Visionary P-B Code Framework Wastewater Characteristics Model Onsite Wastewater Facility Function Environmental Receptor Models Soil Absorption Model Wastewater Dispersal Risk Models Aquifer Protection Waterbody/ WatershedProtection

13. Wastewater Characteristics Model Onsite Wastewater Facility Function Environmental Receptor Models Soil Absorption Model Wastewater Dispersal Risk Models Aquifer Protection Waterbody/ WatershedProtection

14. Wastewater Characteristics Model PARAMETERS BASED ONflow rate/variability, waste loads,facility performance measurements, and environmental receptor models

15. Wastewater Characteristics Model Onsite Wastewater Facility Function Receiving Environment Models Soil Absorption Model Wastewater Dispersal Risk Models Aquifer Protection Waterbody/ WatershedProtection

16. Onsite Wastewater Facility Function Hydraulic Performance Unit Process Treatment Performance

17. Onsite Wastewater Facility Function PARAMETERS BASED ONflow rate/variability, waste loads, treatment process measurements (BOD, TSS, alkalinity, etc.), and environmental receptor models

18. Wastewater Characteristics Model Onsite Wastewater Facility Function Environmental Receptor Models Soil Absorption Model Wastewater Dispersal Risk Models Aquifer Protection Waterbody/ WatershedProtection

19. Environmental Receptor Models Soil Absorption Model Wastewater Dispersal Risk Models A Aquifer Protection Waterbody/ WatershedProtection B C

20. Soil Absorption ModelA Parameters based on • Soil classification relationships • Percolation test relationships • BOD, TSS, FOG • Absorption surface • Operational life • Site hydraulic capacity

21. Aquifer ProtectionB Parameters based on • Appropriate indicator organisms • Pathogens • Acceptable soil horizons • Waste loading analyses • Aquifer water quality • Aquifer standards • Pollutant fate and transport processes

22. Waterbody/Watershed Protection C Parameters based on • Water quality standards • Waste loading analyses • Waterbody quality • Seasonal conditions • Pollutant fate and transport processes

23. Land Surface Dispersal Feature Soil Treatment Zone Pollutant Fate and Transport Processes Groundwater Transport To Site Groundwater Transport From Site