Sulfide Minerals, Wells and Water Quality

Dave JohnsonWDNR

Sulfide Minerals

� Galena� Sphalerite� Arsenopyrite� Millerite

Pyrite and Marcasite

� Pyrite group� Isometric� AX2 where A can be

Fe, Ni, Co, Zn, Hg, Au, Cu, Mn, Os, Ir, Pd, Pt or Ru

� X can be S, As, Sb, Bi, Se or Te

� Relatively stable

� Marcasite group� Orthorhombic� AX2 where A can be

Fe, Ni, Co, Os, Ir or Ru

� X can be S, As, Se or Te

� Less stable

MAJOR BASINS

AND MVT DEPOSITS

Mineral districts

are located on the arches

NURE

NURE

NURE

REGIONAL ARSENIC ANOMALIES SHOWN BY NURE STREAM SEDIMENT ANDHYDROGEOCHEMICAL DATA IN NORTHERN WISCONSIN AND MICHIGANW. F. Cannon, USGS, Reston, VAL. G. Woodruff, USGS, Mounds View, MN

Recognition of the Problem� Elevated levels first discovered in late 1980’s near a

proposed landfill in Winnebago Co.� Private well near Seymour

� thought to be spill but later shown to natural� pH = 2.05, As = 4,300 ppb, Cr = 84 ppb, Cd = 220 ppb,

Ni = 11,000 ppb, Al = 15,000 ppb, Co = 5,500 ppb, Pb = 400 ppb

NER Sampling Program� 1992-94 - private wells

� 3.1% > 50 ppb� 19.4% > 10 ppb

� 1993 AAA� 5 miles from sub-crop

� Drilling recommendations ~85% success at 50 ppb

� Sought greater success by improving recommendations

Sources of Arsenic� Precambrian

Bedrock� Arsenopyrite,

Sulfides� Paleozoic Bedrock

� Sulfides and Metal Oxides

� Glacial Sediments� Sulfides and Metal

Oxides� Anthropogenic

� Pesticides, Industrial, Swine and Poultry manure

Arsenic has been detected in wells in every county in the state. The stars represent locations of with arsenic levels greater than 10 ppb (14%).

Arsenic Release�Oxidation

� Oxygen, Nitrate, Hypochlorite & Other� 2FeS2(As) +7O2 +2H2O = As + 2Fe2+ + 4SO-

4 + 4H+

�Reduction � 4FeOOH(As) +CH2O + 7H2CO3 = As + 4Fe2+ + 8HCO-

3+6H2O

�Replacement� Changes in pH, Phosphate & Silica

�Microbial

Thiobacillus ferrooxidans

4 CountyStatic Water Level - Sulfide Cement Horizon

-400

-300

-200

-100

0

100

200

0 1000 2000 3000 4000

As ppb

SW

L -

SC

H

Water Level Declines In Green Bay

Town of Algoma 1963

740

750

760

770

780

790800

Town of Algoma 1993

740

750

760

770

780790

Town of Algoma 2001

740

750

760

770780

Public Well Sampling

SCH and Hypochlorite� Hypochlorite is

Oxidative Above pH 7.5

� Hypochlorite Addition Increases pH

� Hypochlorite Strips Arsenic from Metal Oxides� Nebraska� Ripon� Residual in Plumbing� SLOH

ScaleDrop pipe from 6 year old well 6% arsenic - 1 gram

1700 ppb

2300 ppb

69,000 ppb

73,000 ppb

100 ppm Hypochlorite

500 ppm Hypochlorite

pH 5.5 pH ~9.5

Well Construction Report

Black Mud and Cuttings from Sulfide Cement Horizon

Arsenic TrendOutagamie & Winnebago

0

1000

2000

3000

4000

5000

1986 1988 1990 1992 1994 1996 1998 2000 2002

Year

As

pp

b

Trends in Individual Wells

� As ppb As ppb Years

� 11 to 3105 in 5

� 0 to 2389 in 7

� 7 to 662 in 7

� 3 to 490 in 3

� 0 to 1700 in 1

� 0 to 110 in 1

MG428

0100

200300

400

Jan-98 Jul-98 Feb-99 Aug-99 Mar-00 Oct-00

Year

AS

ppb

IG602

010002000300040005000

Jun-94 Oct-95 Mar-97 Jul-98 Dec-99 Apr-01Year

As

ppb

Winnebago County

Outagamie County

A = Risk of migration

D = Problem well

B = Good

C = Best but could go dry

Arsenic in Drill Cuttings

Maple Leaf Dairy Well, Vinland Township, Winnebago County

Well Construction Recommendations

� Stay above SCH or go 80 feet below contact� Hard to find

contact� No air rotary� Bradenhead or

grout shoe� Desander� Light disinfection

Special Casing Areas� Protect Public Health and

the Resource� Low compliance with

recommendations� Town of Algoma

� 4/22/02 - 40% >10 ppb� Town of Grand Chute &

Center� 6/15/03 - 35% >10 ppb

� Town of Greenville� 7/15/03

� Town of Neenah� 7/1/04

Expansion of Special Casing Depth Areas

� Increased development and pressure on the resource

� Well interference� Continued research on

health effects� Goal: avoid finishing

wells in high arsenic bearing formations� Stay shallow or go to

Cambrian sandstone

WELL DATA Outagamie and

Winnebago Counties

Dot color indicates geologic formation in which well is completed

Data from WDNR well construction reports and WGNHSWisclith

WINNEBAGO COUNTY SUBSURFACE GEOLOGY

Old Geologic Model

REALISTIC MODEL OF STRATIGRAPHY

FeOOH(As)

FeS2(As)

FeOOH(As) & FeS2(As)

oxidizing

reducing

Development of the Maps� Located 6000+ WCRs � Determined geology

based on WCRs� Contoured top of St.

Peter and Cambrian� Subtracted surfaces

from surface elevation� Red numbers maximum

depth of shallow well option

� Black numbers minimum casing required to be in Cambrian

� Maps on DNR website

Well Construction Requirements

� Shallow well or case to Cambrian sandstone� Upper enlarged drillhole using mud rotary � Bradenhead or grout shoe methods� 15.2 lbs/gal grout weight � Wash rotary lower hole� Light disinfection with NaOCl � Recommend use a de-sander� Air lift development inside casing

Results

� Short cased vs. Deep 50% : 10%� Air vs. Wash Rotary 48% : 18%� Tremie vs. Bradenhead 61% : 7%� Dry vs. Liquid disinfection 40% : 19%� Heavy vs. Light disinfection 38% : 12%� Overall “Special Casing” requirements

have better than 99% success at producing water below 10 ppb

Percentage of wells producing water > 10 ppb

ASR and Monitoring Well Construction Cycle 1

Green Bay ASR� Injected oxygenated, chlorinated water

Shakedown Cycle #1Arsenic

0255075

100125150175200225250275300

6/4/

02

6/18

/02

7/2/

02

7/16

/02

7/30

/02

8/13

/02

8/27

/02

9/10

/02

9/24

/02

10/8

/02

10/2

2/02

11/5

/02

11/1

9/02

12/3

/02

12/1

7/02

12/3

1/02

1/14

/03

1/28

/03

Sample Date

Ars

enic

, tot

al (u

g/L)

MW-1S MW-1M MW-1D Well 10

Injection Storage Recovery

Cycle 2 Well Configuration

Cycle 2 Arsenic

0

10

20

30

4004

/10/

03

04/2

4/03

05/0

8/03

05/2

2/03

06/0

5/03

06/1

9/03

07/0

3/03

07/1

7/03

07/3

1/03

08/1

4/03

08/2

8/03

09/1

1/03

09/2

5/03

10/0

9/03

10/2

3/03

11/0

6/03

11/2

0/03

12/0

4/03

12/1

8/03

Date

Ars

enic

ppb

MW-1S MW-1M MW-1D Well 10 MW1

Florence Bedrock

Florence S&G

Taylor County

� EXAMPLE SITES IN SOUTHEAST WISCONSIN

LOST NATION

MERTON SCHOOLS

TREMAIN

REEK/WOOD SCH.

BELOIT

BIBLE BAPTIST

TIBBETS

Marathon

15 Lead results between 80 and 109 ppb

LaCrosse

� Al 1600� Cd 2� Co 306� Cu 1610� Fe 53.6� Mn 142� Ni 409

LaCrosse

� Al 67300� As 92� Cr 220� Co 909� Fe 672� Mn 2980� Ni 1750� V 239� Zn 4460

LaCrosse

� Al 23200 - 251� As 38 - ND� Co 501 - ND� Fe 376 – 1.2� Pb 47 - ND� Mn 987 - 55� Ni 832 - 8� pH 4.08 – 7.41

� Al 6770 - 6� As 25 - ND� Co 306 - ND� Fe 150 – 10� Pb 18 - ND� Mn 531 - 181� Ni 493 - 8� pH 4.8 – ?

Grant� Al 337� As 19 � Fe 291 � Pb 32� Mn 2050� Ni 496� V 8 � Zn 1960

� Al 10100� As 81� Co 484� Fe 592� Pb 162� Mn 4390� Ni 1090� V 63� Zn 2180

PierceAs 2.3 (57)Al 12Cd 12.6Conductivity 1120Fe 169Pb 927Mn 1340Ni 1700Zn 20600SO4 560

Core hole all shale to St Peter Water at 280 at top of PDCRelated to Rock Elm

Disturbance?

Conclusions� Sulfides may be a problem just about

anywhere in the state� Good wells can go bad over time� Proper well design and construction can

minimize the concentration of arsenic/metals � Water Conservation is important in

preventing release and migration� Appropriate rehabilitation techniques can

prevent release

Conclusions� Think about arsenic/metals

sampling when:� Increasing iron� Low pH� Sulfides are present� Well is on end moraine

� Consider reconstruction/replacement to improve treatment success