Introduction to Decentralized Wastewater Management

1. Introduction to Decentralized Wastewater Management Ligy Philip Department of Civil Engineering IIT madras

2. Introduction Decentralized wastewater systems collect, treat, and reuse or dispose of wastewater at or near its point of generation. It include systems that treat wastewater from individual homes or buildings as well as cluster systems that treat wastewater from groups of two or more houses. Unlike centralized urban wastewater treatment systems, decentralized systems treat wastewater close to the source, typically using small pipes for collecting small volumes of domestic wastewater.

3. Introduction (Contd..) Most cost-effective option esp in rural areas and hilly terrain. Cost-effectiveness depends on a number of factors like population size and density, topography, distance to an existing centralized system

4. Advantages of Decentralized Wastewater Treatment • Often more affordable for small communities • Achieves high removal rates for most pollutants • Less hydrological impact • Can be integrated into a flexible wastewater • system • Can be used as a tool to manage development

5. Disadvantages of DecentralizedWastewater Treatment Potential threat to ground water quality Can be harder to document treatment effectiveness No dilution benefit Risk of failure concentrated

6. Disadvantages of DecentralizedWastewater Treatment Requires greater awareness and participation of homeowners Less familiar to engineers Funding challenges Lack of management structures Fragmented regulatory structure

7. Barriers to Implementation Lack of Knowledge and Public Misperception Homeowners and developers think that houses with centralized systems will carry higher property values and have greater acceptance Legislative and Regulatory Constraints Lack of Management Programs Liability and Engineering Fees Unwillingness of homeowners and developers to accept the liability associated with unfamiliar treatment systems Financial Barriers The funding agencies generally do not assist privately owned systems.

8. Decentralized Wastewater Treatment • Reduce sewer networks • Simplify sewer by applying SOLID-FREE SEWER • Involve local labour and material available • Construct what requires low maintenance and no energy • Generate water and nutrients for irrigation in agriculture and food-garden

9. Effective O & M • Properly constituted and staffed DWM [RME] districts and agencies have proven to be an effective means of assuring the long-term performance of onsite [decentralized] systems. Prince and Davis, 1986

10. Vision Statement • Large-scale decentralized wastewater management systems should be allowed only if a responsible management agency [district] has been designated. Crites & Tchobanoglous, 1998

11. Successful Responsible Management Entities (RME) must include a legal entity that has the technical, managerial, and financial capacity to ensure the viable, long-term, cost-effective, centralized management, operation, and maintenance of decentralized wastewater systems in accordance with appropriate regulations and generally accepted accounting principles. - Yeager and English, 2001

12. The EPA reports • Decentralized systems are used in 25% of US homes and the percentage is increasing • Decentralized is a permanent part of the Nations wastewater infrastructure • More than half of all septic systems are more than 30 years old and at least 10% experience a failure every year • Adequately managed decentralized systems are a cost effective long term option for meeting public health and water quality goals • Local governments need a flexible framework and guidance to tailor their management programs to the needs of the community and watershed

13. Five Management Models • Model 1 - Homeowners Awareness • Model 2 - Maintenance Contracts • Model 3 - Operating Permits • Model 4 - Responsible Management Entity (RME) Operation and Maintenance • Model 5 - RME Ownership

14. Model 1 - Homeowner Awareness • Individual OSSF owned and operated by homeowners • Use in areas of low environmental sensitivity • Treatment technologies limited to conventional systems • Maintenance reminder notification

15. Model 2 - Maintenance Contract • Homeowner system ownership • Professional maintenance • Complex OSSF design such as ATU • Licensed technicians provide proper and timely maintenance • Individual contracts with individual homeowners

16. Model 3 – Operating Permits • Annual permit renewal to assure system performance • Suitable for increased environmentally sensitive areas • Performance based designs with management controls similar to Model 2 • Individually owned OSSF systems

17. Model 4 – Responsible Management Entity Operation and Maintenance • Decentralized systems • May be combined with individual OSSF systems • Highly reliable operation and maintenance • Water quality and sensitive environmental areas • Operating permits are issued to the RME instead of individual homeowners

18. Model 5 – Responsible Management Entity Ownership • Suitable for decentralized systems • Not suitable for individual OSSF’s • Systems are owned, operated and maintained by the RME • Removes property owners from responsibility for the system • Greatest assurance of system performance in the most sensitive of environments

19. Functions of RME Districts • Asset Inventory • System design and installation • Plan review & construction inspection • Operation and Maintenance • Inspections • Notification • Certification • Monitoring • Reporting • Education

20. Successful RME Attributes • Governance capacity • Technical capacity • Managerial capacity • Financial capacity

21. Governance Commonalities • Well defined mission, objectives and goals • Sufficient political will exists • Preexisting laws sufficient to grant the RME authority to accomplish it’s mission, objectives and goals • Operation outside traditional health department paradigm • Big picture focus and NOT micromanagement • Set fees and price structure

22. Technical Commonalities • Biological unit processes • Chemical unit processes • Mechanical unit processes • Component uniformity • System type and compatibility

23. Managerial Commonalities • A paid manager • Effective and timely collection enforcement • Strong board, annual performance reviews • Use generally accepted accounting principles and good record keeping • Strong team of professional consultants • Long term and contingency plans

24. Financial Commonalities • Long-term financial planning • Sufficient cash flow to be self-sufficient • Establish reasonable and sustainable monthly charges • Independent financial oversight • Funds escrowed monthly for replacement cost • Annual audit and performance review

25. Recommendations for RME’s • Existing development using existing treatment systems – Model 3 • Existing development using new treatment systems – Model 4 • New development using new treatment systems – Model 5

26. START Define Service Area This chart makes certain assumptions regarding the service area and system size, age an type Determine number of Connections Try Again Sufficient political will exist STOP Existing laws in place to provide sufficient legal authority to the new RME Continue Select RME legal structure Continue Develop required technical, managerial and financial capacity Petition for RME creation and authorities Develop mission objective &Goals Continue Develop short and long term plans and Contingencies RME Startup

27. Closing Comments As the ethic of professionalism continues to grow within the industry, there will be an acceleration in the formation of new RME’s. These RME’s can bring tremendous benefits to rural and semi-urban areas by providing effective and efficient wastewater service that protects the public health and environment at an acceptable price.