Evaluation of Florida C&D Debris Groundwater Monitoring Data

Presentation discusses:• Results of analysis of

groundwater monitoring data

• Results of groundwater modeling exercise

• Original data set from FDEP– Primarily results from 1997 through 1999

• Additional data were collected by UF– Electronically from the district– Hardcopy upon visiting the district– Most recent data:

• End of 2002• Beginning of 2003

Groundwater Monitoring Data

The Data Set

Number of Landfills 81

Total number of sample points 2966

Total Parameters 67

Background sample points 651

Detection/Intermediate/Other sample points 1410

Compliance sample points 905

Data Evaluation Approach

• Step 1: Identify parameters of concern– Eliminate those inorganic parameters that

were rarely detected and also rarely exceeded a target level

– Eliminate those organic parameters that never exceeded a target level

– Remaining parameters: 20

pH Sulfate Lead

Turbidity Sodium Manganese

Specific Conductance

Total Dissolved Solids

Mercury

Dissolved Oxygen Arsenic Benzene

Temperature Cadmium Total Phenols

Ammonia Chromium Vinyl Chloride

Chloride Iron

Data Evaluation Approach

• Step 2: Comparison of Upgradient and Downgradient Wells for Pooled Data Set

• If greater than 50% of the data were above detection limit– Tolerance Limit Test

• If less than 50% of the data were above detection limit– Test of Proportions

Results of Tolerance Limit Analysis

0% 2% 4% 6% 8% 10% 12% 14% 16% 18% 20%

Ammonia

Sodium

Chloride

Total dissolved solids

Specific conductance

Sulfate

Iron

Turbidity

PH

Temperature

Results of Test of Proportion

• The proportion of samples above the detection limit in the downgradient samples was higher than the proportion above the detection limit in the upgradient samples for:– Arsenic, cadmium, manganese, benzene,

total phenols, vinyl chloride

Graphical Comparison of the Data

• Box and wisker plots were compared for the upgradient and downgradient wells.

Median

25th Percentile

75th Percentile

10th Percentile

90th Percentile

pH

A B C D

pH

4

6

8

10

Turbidity

A B C D

Tur

bidi

ty (

NT

U)

0.01

0.1

1

10

100

1000

10000

Specific Conductance

A B C D

Spe

cific

con

duct

ance

(um

hos)

1

10

100

1000

10000

100000

Dissolved Oxygen

A B C D

Dis

solv

ed o

xyge

n (m

g/L)

0

2

4

6

8

10

12

14

Ammonia

A B C D

Am

mon

ia (

mg/

L)

0.01

0.1

1

10

100

1000

Chloride

A B C D

Chl

orid

e (m

g/L)

1

10

100

1000

10000

Sulfate

A B C D

Sul

fate

(m

g/L)

0.1

1

10

100

1000

10000

Sodium

A B C D

Sod

ium

(m

g/L)

0.01

0.1

1

10

100

1000

10000

100000

Total dissolved solids (TDS)

A B C D

TD

S (

mg/

L)

1

10

100

1000

10000

100000

Arsenic

A B C D

Ars

enic

(ug

/L)

0.1

1

10

100

1000

Cadmium

A B C D

Cad

miu

m (

mg/

L)

0.1

1

10

100

1000

10000

Chromium

A B C D

Ch

rom

ium

(ug

/L)

1

10

100

1000

Iron

A B C D

Iron

(m

g/L)

0.001

0.01

0.1

1

10

100

1000

10000

Lead

A B C D

Lead

(m

g/L)

0.1

1

10

100

1000

10000

Benzene

A B C D

Ben

zene

(ug

/L)

0.01

0.1

1

10

100

1000

Vinyl Chloride

A B C D

Vin

yl C

hlor

ide

(ug/

L)

0.0001

0.001

0.01

0.1

1

10

100

1000

10000

Data Evaluation Approach

• Step 3: Assess the frequency at which groundwater cleanup target levels are exceeded.

• For parameters of concern, calculate the number of sites where a parameter exceeds a target level in a downgradient well where that same parameter it is not exceeded in an upgradient well.

• Only 74 of the 81 sites could be used. Some sites did not have appropriate background wells.

0

5

10

15

20

25

30

Tot

al D

isso

lved

Sol

ids

Am

mon

ia N

itrog

en

Phe

nols

, T

otal

Sul

fate

Lead

Iron

Cad

miu

m

Nitr

ate

Nitr

ogen

Alu

min

um

Ben

zene

Chr

omiu

m

Mer

cury

Sod

ium

Chl

orid

e

Bro

mod

ichl

orom

etha

ne

Cop

per

Ars

enic

Man

gane

se

Bro

mom

etha

ne (

Met

hyl B

rom

ide)

Chl

orof

orm

(T

richl

orom

etha

ne)

Dib

rom

ochl

orom

etha

ne

Vin

yl C

hlor

ide

Ber

ylliu

m

Nic

kel

Van

adiu

m pH

Tur

bidi

ty

Tha

llium

1,1,

2,2-

Tet

rach

loro

etha

ne

1,1-

Dic

hlor

oeth

ene

(DC

A)

Chl

oroe

than

e (E

thyl

Chl

orid

e)

Chl

orom

etha

ne (

Met

hyl C

hlor

ide)

Nitr

ite N

itrog

en

1,1-

Dic

hlor

oeth

ane

1,2-

Dic

hlor

oeth

ane

Dic

hlor

omet

hane

(M

ethy

lene

Chl

orid

e)

tran

s-1,

3-D

ichl

orop

rope

ne

0

5

10

15

20

25

30

Total

Dissolv

ed S

olids

Amm

onia

Nitrog

en

Pheno

ls, T

otal

Sulfat

eLe

ad Iron

Cadm

ium

Nitrat

e Nitr

ogen

Aluminu

m

Benze

ne

Chrom

ium

Mer

cury

Sodium

Chlorid

e

Brom

odich

lorom

etha

ne

Coppe

r

Arsen

ic

Man

gane

se

Brom

omet

hane

(Met

hyl B

rom

ide)

• Of the 74 sites evaluated, 69 sites had at least one exceedance for one parameter in a downgradient well that was not also exceeded in an upgradient well.

Data Evaluation Approach

• Step 4: Look at the data for the sites to see where exceedances are consistent, and where exceedances are one-time or sporadic.

In some cases, the exceedances were consistent.

0

5

10

15

20

25

2/9/1999

8/28/1999

3/15/2000

10/1/2000

4/19/2001

11/5/2001

5/24/2002

12/10/2002

6/28/2003

Date

Am

mo

nia

(m

g/L

)

Background MW-11

Detection MW-12

Detection MW-13

Detection MW-14

0.0

0.5

1.0

1.5

2.0

2.5

3.0

12/6/1999 3/15/2000 6/23/2000 10/1/2000 1/9/2001 4/19/2001 7/28/2001 11/5/2001 2/13/2002 5/24/2002 9/1/2002

Date

Mer

cury

(ug

/L) Background MW-2A

Background MW-6

Detection MW-4

Detection MW-5

Detection MW-7

Detection MW-8

Detection MW-9

In some cases, exceedance was a one time event.

0

5

10

15

20

25

30

Num

ber

of S

ites

Visual Inspection Suggests Likely Exceedance

Visual Inspection Suggests Possible Exceedance

Next Steps

• Statistical comparison of individual site data

• Look at confounding issues such as turbidity

• Examine site histories

Modeling Exercise

• Potential groundwater contamination at C&D debris landfills has been assessed using a simple analytical model.

• Objective was to examine the range of potential groundwater concentrations that might be encountered.

• No specific site was assessed.

MYGRT

• Sponsored by EPRI

• Developed by Tetra Tech Inc.

• Used in past by wood preservation industry

MYGRT

• The MYGRT Code Version 3 is an interactive, menu-driven code for microcomputers. The code predicts the migration of both inorganic and organic solutes in the unsaturated and saturated zones down gradient of sources (i.e. waste disposal sites or spills). The processes included are advection, dispersion, retardation, and decay. The code can simulate problems in one, two, or three dimensions using either horizontal or vertical views.

Definition Sketch

Key Model Assumptions

• Source concentration

• Vertical Infiltration Rate

• Retardation factor in unsaturated zone

• Aquifer characteristics– Gradient– Hydraulic conductivity– Depth

• Retardation factor in aquifer

Consider an Example

• 700 ft by 700 ft landfill• Examine different scenarios

– Use ones outlined in FDEP’s unimpeded discharge study

• Use simulated landfill column data for the source term

• Examine impact of two prime variables– Hydraulic conductivity of the aquifer– Retardation factor

Scenarios

• Coastal Flatland– Gradient 0.001 ft/ft– Hydraulic conductivity 10-7 – 10-3 cm/sec

• Upland Flatland– Gradient 0.001 ft/ft– Hydraulic conductivity 10-7 – 10-3 cm/sec

• Limestone– Gradient 0.005 ft/ft– Hydraulic conductivity 10-5 – 10-3 cm/sec

700 ft

700 ft

Direction of Groundwater Flow

Detection Well at 50 ft from Toe

Compliance Well at 100 ft from Toe

Model Set-Up

Depth of Groundwater = 30 ft

700 ft

Depth to Groundwater Table = 2 ft (limestone) 7ft (coastal flatland) 10ft (upland flatland)

Wells screened from water table down 20 ft

50 ft 50 ft

Source Leachate Assumptions:Simulated C&D Debris LandfillsContaining CCA-Treated Wood

C&D Lysimeter pH

Cumulative Volume (L)

0 20 40 60 80 100 120 140 160

pH

5

6

7

8

9

C&DC&D w/CCA

C&D Lysimeter Arsenic Concentrations

Cumulative Volume (L)

0 20 40 60 80 100 120 140 160

Ars

enic

Con

cent

ratio

n (m

g/L)

0.001

0.01

0.1

1

10

C&DC&D & CCA

C&D Lysimeter Chromium Concentrations

Cumulative Volume (L)

0 20 40 60 80 100 120 140 160

Ch

rom

ium

Co

nce

ntr

atio

n (

mg

/L)

0.001

0.01

0.1

1

10

C&DC&D w/CCA

C&D Lysimeter Copper Concentrations

Cumulative Volume (L)

0 20 40 60 80 100 120 140 160

Co

ppe

r C

onc

entr

atio

n (m

g/L)

0.00

0.02

0.04

0.06

0.08

0.10

C&DC&D w/CCA

C&D Lysimeter DO and Temperature

Cumulative Volume (L)

0 20 40 60 80 100 120 140 160

Te

mp

era

ture

(C

)

5

10

15

20

25

30

35

40

DO

(m

g/L)

0

1

2

3

4

5

6

Temp C&DTemp C&D w/CCADO C&DDO C&D w/CCA

Input Arsenic Concentration

• Arsenic = 2.05 mg/L

• Contributed leachate for 20 years

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

2000 2200 2400 2600 2800 3000

Time (yr)

Ars

enic

Con

cent

ratio

n (m

g/L)

K = 10-3 cm/secKd = 0 L/kg

K = 10-3 cm/secKd = 29 L/kg

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

2000 2050 2100 2150 2200

Time (yr)

Ars

enic

Con

cent

ratio

n (m

g/L)

K = 10-3 cm/secKd =29 L/kg

K = 10-1 cm/secKd = 29 L/kg