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Cornell Waste Management Institute Land Application of Sewage Sludges Topics of Current Concern Ellen Z. Harrison, Director Cornell Waste Management Institute.

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Presentation on theme: "Cornell Waste Management Institute Land Application of Sewage Sludges Topics of Current Concern Ellen Z. Harrison, Director Cornell Waste Management Institute."— Presentation transcript:

1 Cornell Waste Management Institute Land Application of Sewage Sludges Topics of Current Concern Ellen Z. Harrison, Director Cornell Waste Management Institute Dept. of Crop and Soil Sciences

2 Cornell Waste Management Institute Topics of Current Concern Excess nutrients (particularly P) Human health –Aerosols and odor –Water (wells and runoff) –Direct contact –Food chain (animal products, home garden) Long term agricultural productivity/Ecohealth –Phytotoxicity (metals) –Soil health (metals, organic chemicals) Surface water quality –Excess nutrients –Organic chemicals –Metals

3 Cornell Waste Management Institute Health Effects of Land Application "The NRC report issued in July 2002 concluded that, although there is no documented scientific evidence that the 503 regulations have failed to protect public health, further scientific work is needed to reduce persistent uncertainty about the potential for adverse human health effects from exposure to biosolids.” EPA letter, 2004

4 Cornell Waste Management Institute NRC Findings Complex mix of toxic chemicals, infectious organisms, and endotoxins may be present Anecdotal reports of adverse health reactions No “documented scientific evidence” of failure to protect public health Lack of exposure and health info on exposed populations

5 Cornell Waste Management Institute Absence of Evidence is not Evidence of Absence

6 Cornell Waste Management Institute Stakeholder Involvement Called for by NRC Real contribution to research through local knowledge Mutual understanding of limitations of research

7 Cornell Waste Management Institute 11/17/04

8 Cornell Waste Management Institute 11/17/04

9 Cornell Waste Management Institute Unevaluated Pathways of Concern to Human Health Airborne contaminants –Odors –Irritants –Pathogens –Endotoxins –Toxics Water borne contaminants –Pathogens –Toxics –Nitrates

10 Cornell Waste Management Institute Examples DeSoto, Florida Grand Bay, Alabama Menifee, California

11 Cornell Waste Management Institute WERF Incident Response Effort Biosolids Summit – July 2003 Public Partnering Protocol PSC for Incident Response Investigation Project

12 Cornell Waste Management Institute Organic Chemicals in Sewage Sludges Many thousand chemicals in use Few studied Limits of detection can be insensitive Lit search obtained data on 516

13 Cornell Waste Management Institute EPA Soil Screening Levels Risk-based Several exposure paths Trigger for site-specific risk assessment under Superfund Used by NRC as indicator

14 Cornell Waste Management Institute

15 From NRC, 2002 A=SSL, ingestion and dermal

16 Cornell Waste Management Institute Sludge Application at the Cornell Orchard 1978: Ley Creek Treatment Plant (Syracuse, NY) sewage sludge, applied at 244 tons/hectare, till depth 20 cm, 0.08 ratio of sludge:soil 1979 to 1983: test crops grown on plots 1985: entire site was deep plowed, limed and grass planted 1986: apple trees planted, ground cover maintained, mowed 2002: apple trees removed 1994 and 2001 (16 and 23 years later): soil samples collected and analyzed for PAHs, PCBs and PBDEs (PBDEs, non-detect) by Hale and Laguardia

17 Cornell Waste Management Institute Old Orchard Sludge Plot

18 Cornell Waste Management Institute Laguardia and Hale data PAHs - Cornell Orchard (soil), Applied 1978

19 Cornell Waste Management Institute Syracuse NY. WWTP, , PCBs 6600 ng/g (Furr, et al,1976) PCBs - Cornell Orchard (soil), Applied 1978 Laguardia and Hale data

20 Cornell Waste Management Institute Conclusion PAHs, PCBs are persistent in Cornell Orchard 23 years after application –PBDEs below detection limit, consistence with estimated usage rate From LaGuardia, et al VIMS

21 Cornell Waste Management Institute Long-term Effects of Sludge Application One dewatered sludge applied heavily in 1978 Cumulative metal loading ~EPA 503 limits Research –Effect on worms – 2003 field and laboratory

22 Cornell Waste Management Institute Orchard Sampling Locations and Extractable Metal Data

23 Cornell Waste Management Institute Looking for Earthworms

24 Cornell Waste Management Institute Number of Worms in the Field

25 Cornell Waste Management Institute Accumulating Organic Matter

26 Cornell Waste Management Institute Reproductive Effects on Worms: Experimental Data

27 Cornell Waste Management Institute Risk assessments contain many assumptions and policy choices Examination of Several Assumptions that Dramatically Impact Calculated Risks to Water Quality

28 Cornell Waste Management Institute Different sludges and sludge products behave differently Sludge variations Influents vary WWTP processes vary Sludge treatment variations  anaerobic digestion  composting  lime stabilization  heat stabilization/pelletization  alkaline soil amendment

29 Cornell Waste Management Institute What about Class A EQ? No different than Class B EQ Endotoxins Nutrients Chemicals Odor potential Note that processing mode impacts fate and transport, odor potential, pathogens

30 Cornell Waste Management Institute Risk assessments contain many assumptions and policy choices Examination of Several Assumptions that Dramatically Impact Calculated Risks Assessing the Risk to Surface Water Assessing the Risk to Groundwater Assessing the Risk of Cadmium to Home Gardener Using Sludge –How much of each crop does the exposed person eat? –How much Cd uptake into the crops?

31 Cornell Waste Management Institute Map of NYS Showing Relative Size of Watershed and Sludge Site Under 503 RA Assumptions Only 0.24% of watershed assumed to receive sludge. Watershed: 427,000 ha Sludged Area: 1074 ha A small stream may have much greater %of watershed receiving receiving sewage sludges. What is the risk to person fishing such a stream? What is the environmental risk? Example

32 Cornell Waste Management Institute Sludges and Water Quality Movement to Groundwater –In solution –Macropore preferential flow –Enhanced/facilitated transport (movement of contaminant associated with organic matter)

33 Cornell Waste Management Institute Groundwater and 503 RA Rapid flow phenomena aren’t accounted for in EPA model (macropores) One test tube experiment with one sludge and one soil are basis for metal mobilities to groundwater in the EPA risk assessment Substantial dilution or attenuation of leachate before reaching receptor well is assumed (arsenic’s leachate/well concentration ratio is 230)

34 Cornell Waste Management Institute Example: TCLP Leachability of Metals as % total metals Sludge Products Behave Differently Richards, et al 1997

35 Cornell Waste Management Institute Preferential Flow Paths Blue dye reached 6 feet in 1/2 hour Model would predict ~3 years

36 Cornell Waste Management Institute Comparison of Diet Used in EPA Risk Assessment and USDA Recommended Diet 1=EPA daily diet Used Avg. ~1980 consumption Veg consumption has increased Home gardeners eat high veg diet 1+2=USDA Recommended Diet About 2 x as much veg How Much Does the Home Gardener Eat? 12

37 Cornell Waste Management Institute Cadmium Uptake into Leafy Vegetables  4 orders of magnitude difference (Different crops and cultivars, soils, pH, sludges, etc)  Federal 503 risk assessment used geometric mean  Home gardeners eat from a specific, not avg, garden Uptake value used in Cadmium uptake Cadmium Loading Cd uptake into leafy veg, data from field studies

38 Cornell Waste Management Institute Allowable Sludge Cadmium (ppm) 120 EPA calc home gardener risk (not the limiting path) limit (soil ingestion path) simply changing to USDA diet 5 changing to USDA diet and arithmetic mean uptake 1.5 changing to USDA diet and 90th percentile uptake Cadmium Calculation for Home Gardener Eating Crops from Sludge-amended Soils Changing a few assumptions results in very different standard

39 Cornell Waste Management Institute There is no such thing as “Safe” Rather what is the Acceptable Risk? To Whom? Under what conditions?

40 Cornell Waste Management Institute The Case for Caution Our ability to confidently predict risks from land application is very limited –Contaminants concentrate in sewage sludges –Many unevaluated contaminants in sludges (503 -only indicator pathogens and 9 elements) –Present standards are based on a risk assessment with many short comings Liability rests largely with the farmer If problems, hard to prove cause Enforcement and monitoring are inadequate Reports of illness Because:

41 Cornell Waste Management Institute Management Considerations Regarding Use of Sewage Sludges and Sludge Products

42 Cornell Waste Management Institute Setbacks From homes, schools, etc From wells From groundwater From bedrock From watercourses/floodplains Significant aquifers

43 Cornell Waste Management Institute Application Practices Incorporation - if yes, when Pasture application Food crops Stockpiling Soil type –permeability, steep, karst

44 Cornell Waste Management Institute Legal/Administrative Indemnification agreement Record keeping Testing –frequency and/or parameters beyond 503? Archive samples Site specific permits for bulk application

45 Cornell Waste Management Institute Use Nutrient Mgmt plan Application rate – P based? Soil testing Limit annual application amount Limit cumulative amount Limit frequency of application Limit % of a watershed that can be sludged Not on frozen ground Not when soils is within 75% of field moisture capacity


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