Wellhead Protection and Land-Use

By Judy Muehl

Pennsylvania Rural Water Association

• Quantifiable costs – Treatment– Pollution clean-up– Litigation?– Loss of property value and tax

revenue

• Less quantifiable costs – health costs from exposure

It’s Cheaper to Prevent ContaminationIt’s Cheaper to Prevent Contamination

InsectsSmall mammals

Surface water

Groundwater Flow

Barnyard, yards, dumps, mines, septic systems, etc.

Aquifer Contamination

Well HeadContaminationContamination Can be Local or Widespread

soil

Bedrock

Aquifer

XKeep activities at least 50 feet or more from wellhead or spring box

Water Supply Protection Starts at Home!

Septic systemsDrivewaysFertilizer

Pesticides

Publicize

Household HazardousWaste Collection

Programs

Dispose of Household Chemicals Properly

Properly Locate the Water Supply

Wellhead protection zones

well

home and septic system

stream

barn and barnyard

Greatest impact on well

Moderate impact on well

Some impact on well

Direction ofGroundwater Movement

Wellhead Protection Area

• A minimum of 50 feet in every direction

• Preferably more than 50 feet upgradient from the well

• Why 50 feet?– That’s the active recharge area for a typical home well

producing 200 gallons per day.

Wellhead Protection Zones for Public Water Supplies

Red = sources of potential contamination

Zone III

Zone IICapture Zone

Zone I

100 - 400 Ft

Where is the water that needs protection?

Zone II + Zone III = Area of Contribution

Coliform Bacteria

“Indicator” organisms

•Indicate the “potential” for disease-causing bacteria

•E. coli is an example

•One of the most common problems in wells and springs

•Occur in about 50% of private water systems

•Can enter wells and springs from surface runoff, human/animal waste, insects, etc.

•May occur from poor construction or aquifer contamination

Seal the spring box to prevent insects, animals and surface contamination

Sanitary well cap

Grout seal

Good casingSloping Ground

Soil

Bedrock

Groundwater “aquifer”

Water Table

Proper Construction Can Prevent Wellhead Contamination

Photo by Tom McCarty

Don’t Get Carried Away !

Grouting Reduces Bacterial Contamination

0

20

40

60

80

100

No Grout Grouted

Total Coliform

E. coli

% C

onta

min

ated

(Zimmerman et al., 2002)

Standard Well Cap Sanitary Well Cap

Approximately 50% of private wells had obvious insect activity under cap

15% of wells with total coliform bacteria could be solved by installing a sanitary well cap.

Sanitary Well Caps Also Help

0

10

20

30

40

50

60

All New Wells(n=24)

Carbonate(n=6)

Non-carbonate(n=18)

Perc

ent C

onta

min

ate

d Coliform BacteriaE. coli Bacteria

Even a Perfect Well Can Have Bacteria

Agricultural Acid Mine Drainage Commerce/ Industry Residences Waste ManagementStormwater Runoff

Larger Scale Groundwater Contamination

Groundwater Moves !

Common Naturally Occurring Problems in PA Groundwater

• White residue, dull laundry – hardness– 42% of wells and springs have hard water > 180 mg/L– Especially in carbonate (limestone) areas

• Reddish stains, metallic taste – iron– Common in sandstone / shale aquifers

• Black stains, metallic taste - manganese – Often occurs with iron

• Rotten egg odor - hydrogen sulfide gas– Very common in wells in certain shale formations

• Blue stains, metallic taste - corrosive water– Generally caused by low pH and soft water

Corrosivity and Low pH

0

25

50

75

100

NW SW NC SC NE SE

Corrosive (RI > 7.5)Low pH (<6.5)

Region of PA

Pe

rce

nt N

ot M

eet

ing

Sta

nd

ard

Natural Problems Can Cause Other Pollutants

0

10

20

30

40

50

NW SW NC SC NE SERegion of PA

Lead in Private Water Supplies•Based on 1,600 samples•Comes mostly from corrosion of plumbing•High correlation between blue stains, metallic taste and lead

Pe

rce

nt A

bov

e 1

5 p

pb

Land Use Impacts Groundwater

IndustryOrganics, Petroleum Agriculture

Bacteria, Nitrate, Pesticides

MiningMetals, pH

LandfillsOrganics, ?

RoadsChloride, Sodium

HousesBacteriaNitrate

SedimentYard Chemicals

Water Testing Should Target Local Land Uses

Mining Iron, Manganese, pH

Agriculture Nitrate, bacteria, pesticides

Houses Bacteria, nitrate

Gas / oil wells Petroleum, sodium, chloride

Roads Sodium, chloride

Dumps, industry Organic scans

Routine water testing PRIOR to activities is important to document water quality and may provide some legal protection !

How Close do Activities Need to Be?

• In general, homeowners should be concerned about activities that are visible from their home

• In limestone or gravel aquifers, activities further from the home could be important

Example of Land Use Impact

0

1

2

3

4

5

6

7

8

0-100 100-500 500-1000 >1000

Distance to Cornfield (ft)

Ave

rage

Nitr

ate-

N (

mg/

L)

1,600 private water supplies in PA

0

10

20

30

40

50

60

NW SW NC SC NE SE

Occurrence of Nitrate in Private Water SuppliesP

erce

nt A

bove

10

mg/

L

Nitrate most often occurs with intensive agriculture

Region of PA

0

10

20

30

40

50

NW SW NC SC NE SE

Iron > 0.3 mg/LSulfate > 500 mg/L

Iron and Sulfate in Private Water Supplies P

erce

nt A

bove

Sta

ndar

d

Iron and sulfate are most prevalent in coalmining regions

Region of PA

Other Health-Related Pollutants

• Giardia and Cryptosporidium– Protozoans common in surface water– Very rare in wells and springs

• Volatile Organic Compounds (VOC’s)– Around industrials sites, gas stations, urban areas, etc.– Examples – benzene, PCE, TCE, toluene– Widespread in some areas, especially SE Pennsylvania

• Pesticides – Occur in <5% of wells and springs that have been tested– Atrazine is the most common pesticide detected

• Reduces infiltration through compaction (yards) or pavement (roads, sidewalks, driveways) causing less recharge of groundwater

•Homes with wells and public sewer may remove water from the aquifer

•Sprawl moves water use from cities to suburban or rural areas = more users in traditionally rural areas

•Groundwater mining may occur = more withdrawal than recharge

•Common misconception is that homowner owns water under their property

Land Use Can Also Affect Water Quantity

Abandoned WellsAbandoned Wells

Photo: Purdue Extension Service

• May serve as a pathway for future contamination of groundwater

• Should be plugged by a licensed well driller

Graphic: North Dakota State Univ.

Homeowner Actions

• Practice local wellhead protection on their property

• Be aware of current and proposed land use surrounding their property

• Test water annually for pollutants associated with current or proposed land uses