cornell waste management institute land application of sewage sludges topics of current concern...

Cornell Waste Management Institute 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

http://cwmi.css.cornell.edu


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


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


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


Absence of Evidence is not

Evidence of Absence


Stakeholder Involvement

• Called for by NRC• Real contribution to research through

local knowledge• Mutual understanding of limitations of

research


Location (# Incidents)

People Affected Resp GI Burn

Head/ Flu

Lesion/ Rash Bleed Other

AL (1) 10+ x x x x x x x

AZ (1) 100+ x x x x x x x

CA (5) 147+ x x x x x x x

FL (4) 32+ x x x x x x x

IA (2) 4+ x x

MD (1) 3 x x x x

ME (1) 3 x x x

MO (1) 2 x

NV (1) 3+ x x x x

NC (1) 2 x x x x

NH (3) 22 + x x x x x x x

11/17/04


Location (# Incidents)

People Affected Resp GI Burn

Head/ Flu

Lesion/ Rash Bleed Other

OH (6) 14+ x x x x x

OR (1) 4 x x x x

PA (6) 20+ x x x x x x

TN (2) 4+ x x

TX (2) 6+ x x x x

VA (4) 43+ x x x x x x x

WA (2) 6 x x x x x x

WV (1) 3 x x x

WI (1) 2 x x x x

Canada (4) 24 x x x x x x xTotal 21 (50) 454 18 15 11 17 13 9 18

11/17/04


Unevaluated Pathwaysof Concern to Human Health

• Airborne contaminants– Odors– Irritants– Pathogens– Endotoxins– Toxics

• Water borne contaminants– Pathogens– Toxics– Nitrates


Examples

• DeSoto, Florida

• Grand Bay, Alabama

• Menifee, California


WERF Incident Response Effort

• Biosolids Summit – July 2003

• Public Partnering Protocol

• PSC for Incident Response Investigation Project


Organic Chemicals in Sewage Sludges

• Many thousand chemicals in use

• Few studied

• Limits of detection can be insensitive

• Lit search obtained data on 516


EPA Soil Screening Levels

• Risk-based

• Several exposure paths

• Trigger for site-specific risk assessment under Superfund

• Used by NRC as indicator


0

20

40

60

80

100

120

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

# of chem # chem w ith SSLs # chem > SSL

1. Aliphatics2. Chlorobenzenes3. Flame Retardants4. Monocyclic HC5. Nitrosamines6. Organotins7. PCPs8. Pesticides9. Phenols10. Phthalate11. PCBs12. PAHs13. Sterols & Stanols14. Surfactants15. Phosphate.Esters


From NRC, 2002 A=SSL, ingestion and dermal


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


Old Orchard Sludge Plot


Laguardia and Hale data

PAHs - Cornell Orchard (soil), Applied 1978


Syracuse NY. WWTP, 1972-73, PCBs 6600 ng/g (Furr, et al,1976)

PCBs - Cornell Orchard (soil), Applied 1978Laguardia and Hale data


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


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


Orchard Sampling Locations and Extractable Metal Data


Looking for Earthworms


Number of Worms in the Field


Accumulating Organic Matter


Reproductive Effectson Worms: Experimental Data


Risk assessments contain many assumptions and policy choices

Examination of Several Assumptions that Dramatically Impact Calculated Risks to Water Quality


Different sludges and sludge products behave differently

Sludge variationsInfluents varyWWTP processes vary

Sludge treatment variations anaerobic digestion composting lime stabilization heat stabilization/pelletization alkaline soil amendment


What about Class A EQ?

No different than Class B EQEndotoxinsNutrientsChemicalsOdor potential Note that processing mode impacts fate and transport, odor potential, pathogens


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?


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


Sludges and Water Quality

• Movement to Groundwater– In solution– Macropore preferential flow– Enhanced/facilitated transport

(movement of contaminant associated with organic matter)


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)


Example:TCLP Leachability of Metals as % total metals

Sludge Products Behave Differently

Richards, et al 1997


Preferential Flow Paths

Blue dye reached 6 feet in 1/2 hour

Model would predict ~3 years


Comparison of Diet Used in EPA Risk Assessment and USDA Recommended Diet

1=EPA daily dietUsed Avg. ~1980 consumptionVeg consumption has increasedHome gardeners eat high veg diet

1+2=USDA Recommended DietAbout 2 x as much veg

How Much Does the Home Gardener Eat?

1 2


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 503--------

Cad

miu

m u

ptak

e

Cadmium Loading

Cd uptake into leafy veg, data from field studies


Allowable Sludge Cadmium (ppm)Allowable Sludge Cadmium (ppm) 120 EPA calc home gardener risk (not the limiting path)

39 503 limit (soil ingestion path)

- - - - - - - - - - - - - - - - - - - 15 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


There is no such thing as

“Safe”

Rather what is the

Acceptable Risk?

To Whom?

Under what conditions?


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:


Management Considerations Regarding Use of Sewage Sludges and

Sludge Products


Setbacks

• From homes, schools, etc

• From wells

• From groundwater

• From bedrock

• From watercourses/floodplains

• Significant aquifers


Application Practices

• Incorporation - if yes, when

• Pasture application

• Food crops

• Stockpiling

• Soil type –permeability, steep, karst


Legal/Administrative

• Indemnification agreement

• Record keeping

• Testing –frequency and/or parameters beyond 503?

• Archive samples

• Site specific permits for bulk application


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

cornell waste management institute land application of sewage sludges topics of current concern...

Documents

cornell orchard

research slide

california slide

dermal slide

evidence of absence

health info

adverse human health

public health lack of