Wellhead Protection and Land-Use By Judy Muehl Pennsylvania Rural Water Association
Dec 17, 2015
• 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
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
Sanitary well cap
Grout seal
Good casingSloping Ground
Soil
Bedrock
Groundwater “aquifer”
Water Table
Proper Construction Can Prevent Wellhead Contamination
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
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.