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Cleanup of Sewage Lakes: Case Studies in Jeddah and Riyadh

Cleanup of Sewage Lakes: Case Studies in Jeddah and Riyadh. Presentation to National Water Company Forum Day 7 December 2011. Agenda. Ba ckgro und Jeddah Sewage Lake Drivers and project overview Recommended plan Clean-up Completion Al- Nazeem Sewage Lake (Riyadh) Project overview

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Cleanup of Sewage Lakes: Case Studies in Jeddah and Riyadh

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  1. Cleanup of Sewage Lakes:Case Studies in Jeddah and Riyadh Presentation to National Water Company Forum Day 7 December 2011

  2. Agenda • Background • Jeddah Sewage Lake • Drivers and project overview • Recommended plan • Clean-up Completion • Al-Nazeem Sewage Lake (Riyadh) • Project overview • Sediment management • Clean-up status • Project’s Benefits

  3. Wastewater Infrastructure has not kept pace with Growth Demands in Saudi Arabia • Septage issues in nearly all Cities • ~50 % of population served by central collection systems • Country-wide issue that is independent of city size

  4. Sewage Lakes are Common in Middle East and Saudi Arabia • No inventory available for sewage lakes • Jeddah • Only 6 percent of municipal planning area is currently sewered • ~140,000 m3/day hauled by tanker trucks • Riyadh • ~50 percent of population on central collection system • Wastewater pumped from cesspits and trucked to sewage lake • Air pollution from trucks • Significant energyinvestment in trucking

  5. Agenda • Background • Jeddah Sewage Lake • Drivers and project overview • Recommended plan • Clean-up Completion • Al-Nazeem Sewage Lake (Riyadh) • Project overview • Sediment management • Clean-up status • Project’s Benefits

  6. Jeddah Sewage Lake Created in Mid- 1990s Received1500to 2000 tanker trucks/day Up to 50,000 m3/day of sewage Lake grew to 2.8 km2 in surface area

  7. 25 November 2009 flood highlighted major concerns associated with the Sewage Lake

  8. Project Required Rapid Response July 25, 2010 October 2, 2010 • May 2010 • Custodian of the Two Holy Mosques King Abdullah bin Abdulaziz issued a royal decree ordering that the hazardous Sewage Lake be emptied within 1 year • NWC took responsibility for the project • June 2010 • NWC hires Lake Contractor • July 2010 • Water evacuation efforts initiated • Planning consultant hired • October 2010 • Lake Evacuation completed • November 2010 to July 2011 • Sediment clean-up

  9. Planning to Evaluate Environmental Effects and Alternatives for Jeddah Sewage Lake • Flood Management • Removal of the Sewage Lake Dam • Water Management • Evacuation of the Lake • Water Use and Agricultural Activities • Sediment Management • Characterization • Treatment/Management alternatives • Regulatory Requirements • Mitigation Needs • Recommended Plan • Plan Supervision

  10. Lake Sediment Volume Update • Additional sediment depth sampling points • 125 measurements • Sediment depths • Main Lake – <0.5 m • West Lake - <1.2 m • Sediment volume • Main Lake • 300,670 m3 • West Lake • 84,724 m3 • Total Volume = 385,000 m3

  11. Lake Sediment Characteristics Characteristics of silty clay ~ 3-5 cm thick

  12. Main Lake Sediment Characteristics

  13. Lake Characterization for Main Lake and Secondary Lake • Main Lake Data • Data indicated meeting KSA criteria for agricultural use of sludge and US EPA “Exceptional Criteria” • A few sites with elevated petroleum hydrocarbons • Secondary Lake • Showed sediments also met KSA and EPA Criteria • Did show general contamination by petroleum hydrocarbons

  14. Sewage Lake - Ecological Features Open Water and Wetlands Ecosystem Planted Forest Upland Ecosystem

  15. Sediment Management Recommended Plan • Continued drying of sediments • Use mineral material as a drying agent • Sample new areas as can be accessed • Mix thinner sediments in place • When sufficiently dry • Excavate thicker sediments • Spread in upper areas of the Main lake with thin deposits • Mix sediments that have been spread • Conduct “Site Release Sampling Plan” • Verification of site safety • Excavate sediment material littered with trash from former conveyance channel and dispose at a land fill

  16. On-Site Mixing of Organic Sediments Stratified Sediment Before Mixing Topsoil Condition After Mixing Organic Sediment <50% Organic Matter ~0.75 g/cc Mixed Topsoil <25% Organic Matter ~1.0 g/cc 20 cm 30 cm Tillage Mineral Soil <1% Organic Matter ~1.5 g/cc 10 cm Subsoil Subsoil

  17. On-Site Mixing of Organic Sediments Stratified Sediment Before Mixing Topsoil Condition After Mixing Tillage

  18. Jeddah Sewage Lake Cleanup Status 29 March 2011 • October 2010 • Lake Evacuation completed • November - December • Sediment drying and mixing activities • Additional sediment characterization • December-February 2011 • Completion of report documentation • Additional rainfall events partially refilling the lake to ~2m depth • March – August 2011 • Pumping to evaporation ponds • Continued sediment drying and mixing activities • Completed site release sampling

  19. Site Release Sampling Completed • Lake evacuation • Delayed because of availability of pumps • Started in March 2011 • Completed in May 2011 • Sampling grid • Final grid included 205 cells • Thick vegetation along margins prevented sampling of infrequently flooded areas

  20. Summary of Results • Total Organic Carbon – low levels indicating sediments are stable • Metals –maximum values <12% of criteria • Microbiological • Fecal Coliform – Maximum value of 24 MPN/g versus standard of 1000 MPN/g • Parasite eggs – None detected • Petroleum Hydrocarbons • Only 3 sites showed some values exceeding levels of 2000 mg/kg for Total Petroleum Hydrocarbons • Additional mixing and re-sampling significantly reduced levels Cleanup plan was executed and site release sampling demonstrated site was safe for turnover back to the municipality

  21. Sediment mixing completed throughout the lake areas

  22. Upper Portion of Former Lake Area being used for Camel Grazing

  23. Agenda • Background • Jeddah Sewage Lake • Drivers and project overview • Recommended plan • Clean-up Completion • Al-Nazeem Sewage Lake (Riyadh) • Project overview • Sediment management • Clean-up status • Project’s Benefits

  24. Background on Al-Nazeem Lake • Lake has been used for approximately 20 years • Received • 1000 to 1500 trucks per day • ~20,000 to 30,000 m3/day • Mixture of Domestic and Industrial Waste • Domestic waste eliminated in January 2011 • Industrial waste eliminated in Mid-May 2011

  25. Lake Cleanup Focus • Lake area is ~3.5 km2 • When cleanup began in June/July 2011 – very little water remained • Cleanup focus • Sludge characterization • Sludge drying • Sludge treatment • Lake are divided into 4 zone with 39 separate lakes

  26. Cleanup Plan for Sediments focused on Characterization and Onsite Disposal

  27. Characterization Results Provided Clear Direction for Cleanup • Characterization focus • Metals • Microbiological indicators • Petroleum hydrocarbon fractions • Volatile and Semi-volatile compounds • Results • Zones 3 & 4 – no results exceed criteria • Zones 1 & 2 • Metals and hydrocarbon issues at several locations

  28. Initial work focused on facilitating drainage and drying of sludge

  29. Project Clean-up is Nearing Completion Clean-up has involved excavation, mixing and combining with clean sand Lake contractor is conducting verification sampling Upon completion – site release sampling will be conducted by an independent laboratory

  30. Agenda • Background • Jeddah Sewage Lake • Drivers and project overview • Recommended plan • Clean-up Completion • Al-Nazeem Sewage Lake (Riyadh) • Project overview • Sediment management • Clean-up status • Project’s Benefits

  31. Sewage Lake Clean-up Projects Address Public Health and Aesthetic Issues NWC Efforts have eliminated two long standing health hazards Detailed investigations have led to environmentally sensitive solutions Jeddah Lake project recognized with GLOBAL WATER INTELLIGENCE Reuse Project of the Year (reuse of sludge to enhance soils)

  32. Cleanup of Sewage Lakes:Case Studies in Jeddah and Riyadh Presentation to National Water Company Focus Day 7 December 2011

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