strategy for containment and treatment of … for landfill leachate...s.w. ottawa county landfill...

S.W. Ottawa County Landfill

Strategy for Containment and Treatment of Contaminated Groundwater

Barbara Marczak, P.E., Project Manager, P&N

Joe Hebert, Chief Operator, OC DPU

August 11, 2010

Landfill Operation

� 1968 – Landfill Constructed

� 1968 - 1980 – Site in Operation (“State of the Art”)

� 1979 – Groundwater contamination discovered

� 1980 – Site Closed

� 1981 – Site Capped

� 1983 – NPL Registered (SUPERFUND)

GW Investigation & Cleanup

� 1979-2009 – Groundwater Investigation� 1987 – Purge & Treatment System Installed� 1992 – 1994 - More wells and treatment added� 1996 – Proposed upgrades� 2003 – Watermainextended Lakeshore Drive� 2006 – New landfill cover� 2008 – New purge wells� 2009 – Modified treatment system

GW Contamination Investigation

� 1979-2009 – Installation of 115 Monitor Wells

� Basic Hydrogeology1. Unconfined Aquifer

2. Groundwater occurs 5 to 25 feet below ground

3. Fine to Coarse Sand, Surface to 40-50 feet

4. Silt/Clay 40-50 feet deep

5. Hydraulic Gradient: 0.004 ft/ft

6. GW Flow Direction: S.W. then West – 1-3ft/day

GW Contamination Investigation

� Contamination

� Indicator Parameters: Specific Conductance & Iron� Primary Contaminants: Volatile Organic

Compounds (ppb range)� VOC contamination is largely gone within 500 to

1,000 feet of the landfill� Elevated iron seen further out as a result of

biodegradation of VOCs through iron reduction� No VOCs above health based drinking water criteria

except next to landfill

SWOCLF Contamination Plume

Purge wells and Pipelines

1987 Groundwater Remediation

I. Purge Wells● 7 purge wells – 2 near landfill, 5 downgradient

● 3 purge wells added in 1992

II. Treatment System (1 MGD)� Iron Removal

1. Oxidation with Potassium Permanganate2. Filtration

� VOC Removal1. Carbon Adsorption

2006-2008 Remediation Improvement

III. Groundwater Remediation ($1,800,000)

� Installed 4 new purge wells to improve capture of contaminants.

� The only current wells that exceed the NPDES permit for discharge are next to the landfill

III. Groundwater Remediation� Benefits

� Reduced flow to treat by one-half� Capture and treat twice as much contamination� Reduced maintenance on purge wells� Capture more contaminated groundwater

2006-2008 Remediation Improvement

Design Criteria

PARAMETERS

Flow rate (gpm)

Iron (mg/l)

Benzene (µg/l)

Chlorobenzene (µg/l)

Ethyl Ether (µg/l)

Tetrahydrofuran (µg/l)

Influent Pre-upgrade

300--700

9

9

11

12

9

Proposed

500

Conc.

25

22

40

20

15

-30%

Mass

+400%

+400%

+400%

+400%

+400%

Design Criteria

PARAMETERS

Flow rate (gpm)

Iron (mg/l)

Benzene (µg/l)

Chlorobenzene (µg/l)

Ethyl Ether (µg/l)

Tetrahydrofuran (µg/l)

Effluent

500

Conc.

<0.3

5

5

none

none

NPDES

Conc.

5

5

5

none

none

DW

Conc.

0.3

5

100

1,500

95

Feasibility / Pilot Testing

•Treatment Options / Costs

•Pilot testing

2006-2008 Remediation Improvement

III. Groundwater Remediation� Improved the treatment system. (.72 MGD)

� Using aeration for oxidation to reduce chemical use and cost.

� Added a new system for iron removal: flocculation, settling, & filtration.

� No changes to carbon adsorption for VOC removal.� System is automated to run with no operator

present

Process Schematic

Oxidation

DeloachIndustries aeration and detention unitInduced draft aerator @ 3,125 CFM+ 15K gal. detention tank (30 minutes)

Purpose� Convert Iron from dissolved Fe2+ (Ferrous) to Fe3+ (Ferric)� 100% conversion of Iron is needed. � Partial removal of organics expected

Added 60 cfmFine Bubble Diffusion within detention tank

Iron Conversion

0

5

10

15

20

Influent Aeration Aeration +KMnO4

NaMnO4

Iron

Con

c.

(mg/

l)

FerricFerrous

Iron Conversion

0

5

10

15

20

Influent Aeration Aeration +KMnO4

NaMnO4

Iron

Con

c.

(mg/

l)

FerricFerrous

45% Conversion

Iron Conversion

0

5

10

15

20

Influent Aeration Aeration +KMnO4

NaMnO4

Iron

Con

c.

(mg/

l)

FerricFerrous

71% Conversion

Iron Conversion

0

5

10

15

20

Influent Aeration Aeration +KMnO4

NaMnO4

Iron

Con

c.

(mg/

l)

FerricFerrous

100% Conversion

Chemical Oxidation

� Approx. 0.5 lb oxidant to 1 lb Fe2+

� Complete iron conversion from Fe2+ to Fe3+

� 108 lbs/day Fe2+

� KMnO 4 @ $4.75 / lb ($94,000 year)� NaMnO4 @ $0.95 / lb ($19,000 year)

O = Mn - O- Na+

O =

O =

Flocculation and Settling

� ParksonLamella plate settler (.72 MGD)� Primary Settling and Removal of TSS and Fe3+

� Design loading rate: 0.55 gal/ft2/min.� Aeration caused poor performance!

� Coagulant optimization and testing• Aluminum Sulfate @ > 60 mg/l ($26,000 year)• *Polyaluminum hydroxylchlorosulfate @ 40 mg/l• ($24,000 year)

� Polymer optimization� Anionic polymer w/Alum @ 5 mg/l ($16,000 year)� Anionic polymer w/poly Al @ 1 mg/l ($3,200 year)

Filtration

� ParksonDynasandDSF-100 SBTF• Removal of TSS and Fe3+

• 92 ft2 surface area• Design loading rate: 5.43 gal/ft2/min.

• Sand media: Effective size 1.2mmUniformity Coefficient = 1.5

• 40 inch bed depth

• Continuous backwash without interrupting flow

• <0.3 ppmFe3+ performance requirement

BenefitsBenefits••Continuous (moving bed) BackwashContinuous (moving bed) Backwash••Better depth filtrationBetter depth filtration

Constant Constant headlossheadlossContinuous backwashContinuous backwash

••Low mechanical & hydraulic energyLow mechanical & hydraulic energyrequirementsrequirements

No redundancy req.No redundancy req.No costly ancillary supportNo costly ancillary support

••Process: CounterProcess: Counter--current separationcurrent separation

DynaSandDynaSand®® FilterFilter

UpflowUpflow

Settling and FiltrationPost Oxidation

0

10

20

30

40

50

60

Influent Lamella Dynasand

TS

S /

Fe3+

mg/

l

TSSFerric

Settling and FiltrationPost Oxidation

0

10

20

30

40

50

60

Influent Lamella Dynasand

TS

S /

Fe3+

mg/

l

TSSFerric

73% removal

81% removal

Settling and FiltrationPost Oxidation

0

10

20

30

40

50

60

Influent Lamella Dynasand

TS

S /

Fe3+

mg/

l

TSSFerric

47% removal (step)

85% removed overall

75% removal (step)

95% removed overall

Carbon Adsorption

� Effective VOC Removal

� 20,000 lbs carbon each� Series flow configuration

Volatile Organic Compounds

0

10

20

30

40

50

60

70

Influ

ent

Aer

atio

n +

Filt

ratio

n

NaM

nO

4 +

Filt

ratio

n

Car

bo

nE

fflu

ent

VO

C

Con

c. (

µg/

l)

TetrahydrofuranEthyl EtherBenzeneChlorobenzene

0

10

20

30

40

50

60

70

Influ

ent

Aer

atio

n +

Filt

ratio

n

NaM

nO

4 +

Filt

ratio

n

Car

bo

nE

fflu

ent

VO

C

Con

c. (

µg/

l)

TetrahydrofuranEthyl EtherBenzeneChlorobenzene

49% removal

ND

Volatile Organic Compounds

100% removal

0

10

20

30

40

50

60

70

Influ

ent

Aer

atio

n +

Filt

ratio

n

NaM

nO

4 +

Filt

ratio

n

Car

bo

nE

fflu

ent

VO

C

Con

c. (

µg/

l)

TetrahydrofuranEthyl EtherBenzeneChlorobenzene

ND

Volatile Organic Compounds

100% removal

Conclusions

�Effective aquifer capture through hydro geological modeling and testing

�Pilot testing always an invaluable tool

�Micro bubbles will prevent proper settling of floc

�Ensure strict manufacturer performance guarantees

BMarczak@preinnewhof.com

JHebert@ottawacorc.com