track a - Water Resources Center

Estimating Salt Budgets to Predict Chloride Threats to Municipal Wells
From Salt Institute
Presented at Minnesota Water Conference 2015
October 13, 2015
John Jansen, P.G., Ph.D.
The Good:
In Pre-Modern Times:
• Salt was once a limited strategic resource
• Trade routes of thousands of miles existed for centuries
to move salt around the Middle East
• Salt production is the weapon Gandhi used to challenge
the English occupation in India
• The word “Salary” has its origins in Romans paying
soldiers in salt
• Being worth your salt was a literal concern
In Modern Times:
• Mined salt has made salt cheap and plentiful
• Deicing with road salt has made winter travel faster and safer
• U of Marquette study found road salt cuts accidents by 88%
“Snow fighters may save more people the fire fighters”
• Going back to ice covered roads is impractical unimaginable
to most people
Environmental and Health Risks of Road Salt Contamination
Area of Impact
Human health
Infrastructure
Examples of Impacts
•
•
•
Hypertension from excess sodium in drinking water
Ferrocyanide, added to chloride salts to prevent clumping, can
release 25% cyanide ions in presence of sunlight
Corrosion of concrete reinforcing rods in road, bridges,
parking structures, etc.
•
•
•
Vegetation
•
•
•
Soil
•
•
Corrosion costs estimated at $3.5 to $7 billion per year in the U.S.
Corrosion protection practices increase the cost of auto
manufacturing by nearly $4 billion/year
Corrosion protection costs estimated at $8.3 billion/year for
highway bridges, and $109 billion for epoxy coating;
Osmotic imbalance in plants, inhibiting water absorption
and reducing root growth
Inhibition of seed germination and root growth for grasses
and wildflowers (for NaCl as low as 100 ppm in soil)
Competition to native species from salt-tolerant invasive species
Inhibition of soil bacteria (for NaCl concentrations as low as 90
ppm), compromising soil structure and increasing erosion
Accumulation of salt, particularly sodium, in soil over time,
reduces soil fertility and affects soil chemistry
Groundwater
•
Remediation of salt contamination in drinking water estimated at
$10 million nationally
Wildlife
•
Compromised health in birds ingesting salt at 266 mg/kg;
median lethal dose in birds and mammals is 3,000 mg/kg
Aquatic life
•
Decreased dissolved oxygen and increased nutrient
loading, promotingeutrophication
Release of toxic metals from sediment into the water column
•
•
•
•
Reduction of number and diversity of macroinvertebrates
Critical tolerance values in 10% of aquatic species exceeded
for prolonged exposure to chloride concentrations >220
mg/L
Median lethal dose (7 days exposure to salt) for 17 species of fish,
amphibians, crustaceans ranges from 1,440 – 6,031 mg/L (mean
value of 3,345 mg/L)
From City of Madison Salt Report 2006
• Secondary Drinking water MCL for Cl 250 ppm
(based on taste issues)
• USEPA drinking water equivalency guideline for Na
20 ppm (based on sensitivity of people with
hypertension)
• USEPA Cl Surface water standards; Acute 860 ppm
and Chronic 230 ppm (based on toxicity for fish)
• IEPA Surface water standards; Acute 500 ppm
Fingerprinting Source of Chloride with Halide Ratios
• Chloride/Bromide ratios diagnostic of chloride source
• Road salt and septic effluent/waste water occupy
same range
• Other indicators can be used to identify septic
effluent and waste water
• Trace ferrocyanide (anti-caking agent) can be used as
road salt indicator
• Road Salt is usually the biggest culprit in the northern
states
• Road salt is typically 60 to 90% of the loading
• Other sources like water softeners and sewage
treatment plants are secondary
Application Rates of Road Salt are Still Going Up
source: Madison and Dane County Road Salt Report, 2012
https://illinois.edu/blog/dialogFileSec/2095.JPG
Data from Salt Institute, 2011
• US road salt use over 20 million tons by 2010
• National application rates have tripled since 1980 despite aggressive reduction efforts
Chloride levels Are Rising in Most Surface water Bodies
From City of Madison Salt Report 2013
• Chloride levels are three to five times higher in Madison’s lakes over the last 50 years

37 lakes, streams & wetlands on DRAFT 303(d) list for
chloride in the TCMA (roughly 10% assessed) – 2
Chloride TMDLs completed

41 waters determined to be “High Risk” in TCMA


Defined as having values within 10% of the standard or at
least one exceedance of the standard
Groundwater levels of chloride in the TCMA are increasing

30% of wells above the standard

Impact on baseflow levels of chloride is important

USGS groundwater data also shows Significant increase in
chloride since 1996 in Upper Mississippi River Basin

Metropolitan trend analysis for the Mississippi, Minnesota
and St. Croix Rivers in TCMA all show increases in chloride
(compared to the 10 year average)
Source: Brooke Asleson, Minnesota Pollution Control Agency
Chloride Levels in Minnesota’s Sand and Gravel Aquifers
From Kroening 2014 (MPCA)
• Wells with elevated Chloride are clustered near cities
• Highest levels in Twin Cities area but other areas having problems
• University of Minnesota study found that 78% of the chloride used is
being retained in the TCMA
Discrete Sources Can Generate Spatially Limited Plumes
Locally Grown Salt Water Intrusion for the Landlocked
Downward flow from density
flow and/or vertical gradient
A Question of Balance:
Developing a Salt Budget for a Wellfield
• What salt loading can the groundwater system
handle?
• Is the safe level enough to keep the roads clear?
• Can be done for a well, stream, or basin
• Loading limits depend on soil type, recharge rate
and Groundwater Flow Pattern
• Level of effort can be matched to the need for
accuracy – start simple and increase level of
effort if needed
• Target values can be fit to sensitive receptors
South Well Field
City of Marshfield, WI
• Oldest well field still in use by City
• Currently 5 active wells, 2
abandoned
• 4 wells several decades old
• Located in an area with a state
highway, an airport, and many
parking lots
• Capture zone delineated by two
previous studies
South Well Field Chloride Trends
•
•
•
•
Cl levels doubled to tripled from 1985 to 2011
Apparent declining trend in 2 of 5 wells from 2011 to 2013
Data sparse so trends from 1985 to 2011 are speculative
Sodium levels exceed 30 ppm in wellfield (58 ppm in 1998)
Salt Loading in Capture Zone
• Salt load calculated using lane miles and average
salt loading rate from WDOT and City Road
Department
• Lower application rates used for parking lots and
runways (may actually be much higher)
• Used capture zone from both wellhead studies
• Estimated loading rate 926 to 1575 tons/yr
Calculating Maximum Groundwater Chloride Concentrations
• Using estimated range of recharge rates (3 to 7 in/yr) average Chloride levels
could exceed 2,500 ppm if all the water was recharged – NOT REALITY
• Using an estimated percentage of infiltration of about 25%, the average
chloride concentrations of recharge would be 360 ppm (not implausible
given concentrations in other wells)
• Using a lower level infiltration estimate (10%) predicts average chloride
concentration of recharge of about 130 ppm (similar to recent values in
wells)
• Capture zone for the well field indicates that the bulk of the water in the
aquifer is probably less than 5 or 10 years old
• Chloride levels have reached equilibrium for current application rates
• No large increases likely if loading rate does not rise
• Any reductions in loading will result in improvements within a few years
• City is currently reducing salt loading and rerouting parking lot runoff to
continue decreasing trends
• Well fields with more critical problems may require monitoring wells,
transport models, extraction wells, and more aggressive follow up work
• Budget approach is inexpensive screening tool
Sodium and Chloride Concentrations at Production Well AVY-1
Ashland,
New Hampshire
Production Well AVY-1
Ashland, New Hampshire
160
Chloride
Sodium
140
Production Well AVY-1
Linear (Chloride)
Linear (Sodium)
Concentration (mg/l)
120
100
80
60
40
Wellhead Protection Area (WHPA)
Date
Dec-08
Dec-07
Dec-06
Dec-05
Dec-04
Dec-03
Dec-02
Dec-01
Dec-00
Dec-99
Dec-98
Dec-97
Dec-96
Dec-95
Dec-94
20
Screen Elevations and Average Chloride Concentrations
PW AVY-1
D
Upwelling toward well
Scavenger Well in plume??? Density driven downward
migration from source area
Green Storm Water Management May Be
Making Groundwater Problems Worse
•Several states and local governments are
adopting infiltration basins as a “green” solution
to storm water
•Most rules are surface water driven, do not
account for groundwater quality
•Other chemicals also a threat (fertilizers,
pesticides, VOCs, metals…)
•Time lag of years to decades may make
solving the problem by source reduction too
little and too late
•Are we trading a 2 week problem in surface
water for a multi-decade problem in
groundwater?
Mitigation
• Reduce loading to groundwater
• Divert snow melt away from recharge basins
• Keep snow stockpiles out of capture zones
and on impervious surfaces that drain to
surface water
• Identify salt hot spots in soils and aquifer and
remove or dilute
• Managed aquifer recharge with low salt
water to dilute salt concentrations and flush
out of aquifer
• Use scavenger wells or barrier wells?
• Locate new wells in low salt load areas and protect those areas
Treatment
• Blending with low salt water
• Requires suitable water source
and piping to blending point
• Reverse osmosis
• High energy requirements
• Brine disposal issues
• High cost
To be avoided if at all possible
End of the Road For Me
Note: not caused by road salt
JENNY
JASPERSON,
MPCA/UMD
FLOOD EFFECTS
ON
SW-GW INTERACTIONS
KAREN GRAN,
UMD
JOE MAGNER,
EAST BRANCH AMITY CREEK
UMN
JOHN
SWENSON,
UMD
OUTLINE
Scope
Study Area
Data Collection
Background/Broader Results
SW/GW Response to the Flood
PROJECT SCOPE
 Examine GW-SW interaction and water budget
characterization at watershed and reach scales in a coldwater
stream with a healthy and stable brook trout population.
 Identify locations of GW-SW exchange, upwelling zones,
storage zones
 Look at SW/GW levels and composition; and seasonal
variation
 Evaluate change in these relationships as result of a major
flood
WHY EAST BRANCH AMITY CREEK?
Native Brook Trout Population
BKT densities
 95 th Percentile in greater Arrowhead Region
 Supports all age classes
 No stocking of BKT since 1993
Suspected GW inputs
Good/Excellent Thermal Conditions
 (Primary Growth Range = 96%, 2011)
 >60% flow contribution to lower gage
during low to mid-range flows
MPCA’s WRAPS Schedule
(Lake Superior South – 2011 start)
STUDY AREA
STUDY AREA
Lake Superior South
Major watershed
Main tributary to Amity
Creek.
Geology: Bedrock, Till,
Alluvium
Distinct Features
EAST BRANCH AMITY CREEK
Entrenched Stream Valley
Lateral movement of stream in clay walls
Till/alluvium mix
Remnant channels & inactive beaver dams
DATA COLLECTION
DATA COLLECTION
Water Level Data
Stable Isotopes
of O & H
1-Flow/level gage
9-monitoring wells
Timeframe
2010-2014 Data
Complete Years: 20112012
DATA COLLECTION
P V C w i t h b o t t o m s c re e n
Depth Range:
2.33 – 3.67 feet below surface
HOBO loggers
Soils: Mix of sand, gravel, and
clay
250 feet
ISOTOPE SAMPLE LOCATIONS
 Precipitation
 SW
 GW
 Snowmelt
 Rain event
 Baseflow
2012 WEATHER
• Mild Winter with lower than average
snowpack
• 3-inch rain event in May
• Major flood event: June 19th -20th
• Extreme Drought declared in
September
BROADER STUDY
DEFINING FLOODPLAIN STORAGE
Near Bank Storage:
Stream water moves into the banks during periods of high
flow and typically returns to the stream channel within
day(s) or weeks.
Depressional Storage:
Precipitation or above bankfull stream water is captured in
depressions, infiltrating through the soil profile.
Depending on the system, water returns to the stream may
take weeks, months, or years.
WATER LEVEL COMPARISON
Depth-to-water Duration Curves
Continuous Levels, 2011
Depressional
vs
Near Bank
ISOTOPE HYDROGEOLOGY
Isotopes of an element
have similar charge, but
different masses.
Diagram source: http://www.ces.fau.edu/nasa/module-3/how-is-temperature-measured/isotopes.php
 The amount of 18 O compared to
using Del Notation:
16 O
(or 2 H to H) is expressed
δ18O ‰ = (18O/16O)sample – (18O/16O)standard
x 1000 ‰ VSMOW
(18O/16O)standard
 Parts per thousand enrichment or depletion relativ e to the standard
 VSMOW is the standard (Vienna Standard Mean Ocean Water)
ISOTOPE DATA
δD = 8.37 δ18O + 15.47
R2 = 0.9823
Craig, 1961. Linear Relationship δD = 8δ18O + 10 , water that has not been evaporated.
SW-GW RESPONSE TO
FLOOD
June 19 th -20 th ,
2012
DULUTH FLOOD, 2012
- 500 Year Storm
- 7.5-8.5 inches
- <24-hr Duration
STREAM FLOW (CFS) RESPONSE
800
East Branch Amity Creek, Duluth MN - H02037005
600
400
200
0
4/10/11
2000
7/19/11
10/27/11
2/4/12
5/14/12
8/22/12
Amity Creek at Occidental Blvd, Duluth MN - H02038001
1500
1000
500
0
04/07/11
07/16/11
10/24/11
02/01/12
*HECRAS model used to Model Ungauged High Flows
05/11/12
08/19/12
STREAM FLOW RESPONSE
Photo: MPCA
5/24/12 – 3-inch event
http://content.govdelivery.com/accounts/MNPCA/bulletins/c97fd0
Photo: www.lakesuperiorstreams.org
June 20th, 2012 – falling limb of flood event
VALLEY WAS INUNDATED
JULY 21st – TWO DAYS AFTER
PEAK FLOWS
Debris in trees, 3 - 4’ above
ground in floodplain
Bank erosion where channel
abutted steep valley walls
Areas of channel aggradation and
incision.
One well was damaged & all well
covers were removed by water
One well was filled in with sand.
Remnant channel was scoured.
GEOMORPHIC RESPONSE
INCISION & AGGRADATION
Slope Break
Slope Break
Slope break at old
(2010) beaver dam =
Response control
Lateral Movement at
bends
Upstream side of Break
• Alluvial fill
Downstream side of
Break
• In-channel incision
• Debris caught on banks
flow
REMNANT CHANNEL
Post-Flood
Pre-Flood
15+00
13+00
13+00
Channel Incision and loss of organics, exposing gravel alluvium.
FLOOD EFFECTS DATA
• CHANGE IN GW LEVELS
• CHANGE IN GW COMPOSITIONS
DROP IN GROUNDWATER LEVELS
D RY W E L L S = F I RS T CL U E
Slope
break
GROUNDWATER LEVELS
I N CI S ION I N MA I N CH A N N E L & RE MN A N T
Near Bank
Depressional
/Remnant
mw12+00
2012: -0.84’
2013: -0.60’
mw13+00
2012: -1.43’
2013: -1.02’
Elevation (ft)
1019.5
1017.5
mw12+00
mw13+00
1015.5
1013.5
3/15/10
9/15/10
3/18/11
9/18/11
3/20/12
9/20/12
3/23/13
9/23/13
GROUNDWATER LEVELS
A RE A S O F N O N O T I CE A BL E I N CI S ION
Near Bank
mw4+00
2012: -0.11’
2013: +0.17’
Elevation (ft)
1028
1026
mw4+00
1024
1022
03/15/10
09/15/10
03/18/11
09/18/11
03/20/12
09/20/12
03/23/13
09/23/13
REDUCED DRY SEASON
GROUNDWATER LEVELS
8+00, not installed 2013
D
R
Y
D
R
Y
• Drop in GW levels in remnant channel and
East Branch Amity-below slope break.
• Slight rebound in 2013
D
R
Y
D
R
Y
TEMPORARY CHANGE IN STREAM
BASEFLOW COMPOSITION
Post-Flood
2012
Baseflow
2014
Baseflow
2012 –
3-inch
Pre-flood
Rain Event
2012
Snowmelt
2010
Baseflow
NEAR BANK EXCHANGE
• Near Bank GW ≈ stream water → frequent interaction
• During small rain event, inside bend well had more SW signal
• No obvious changes in relationships due to the flood.
DEPRESSIONAL GW
ISOTOPIC SIGNATURE
• Depressional GW is stable. Disconnected from precipitation, stream flow, &
remnant SW.
• Water in remnant channel is less affected by precipitation & runoff than the
stream.
DEPRESSIONAL GW
ISOTOPIC SIGNATURE
• Sept 2012:
• Depressional GW has changed, now having a heavier signal.
• No barrier between SW & GW in the remnant channel.
• Stream has a slightly different signal.
• 2013:
• Depressional & outside bend Near-bank GW are approaching
“Original water” signal
DEPRESSIONAL GW
ISOTOPIC SIGNATURE
Ideas & Interpretations:
• Depressional GW changed, having a heavier signal.
• Floodwaters replaced or mixed into the shallow GW table.
• No barrier between SW & GW in the remnant channel.
• Incision flushed out organics and reduced the barrier OR
• All water in the system had been replaced or re-mixed.
• Sept 2012: Stream has a slightly different signal than remnant & wells.
• Strong influence from upstream site SW13?? Assuming different
composition at SW13.
• Depressional GW & outside bend Near-bank GW are approaching
“Original water” signal by July 2013.
• 2013 was a more typical climate year, including more snowmelt
contributions.
• GW is re-establishing the pre-flood composition
SUMMARY
 Floodplain Storage behaves differently than Bank Storage.
Differences in depth-to-water, rainfall response time, & exchange
with SW.
 Evaporative Losses differ throughout watershed. Strong GW
signal entering watershed 1.5 upstream of study reach
 In areas of flood-induced incision, the GW table dropped.
 Groundwater was replaced or re-mixed during flood event.
 Groundwater signal was trending back toward the “original
water” or a more negative signal one year later.
 Groundwater levels remained at lowered levels with a slight
rebound one year later.
A SPECIAL THANKS TO:
MPCA & MPCA Staff
 Pat Carey
 Suzanne Hanson
 Andrew Streitz
 Pete Knutson
 Andrew Swanson, former MPCA
 Brittany Story
 Jeff Jasperson
 Mike Kennedy
 Tom Schaub
 Tom Estabrooks
 Zach Moore, MN DNR (former
MPCA)
 University of Minnesota
Duluth & Twin Cities
 Rich Axler, NRRI
 Howard Mooers, UMD
 Jerry Henneck, NRRI
 Keith Anderson & TSA3
 Tim Beaster, SSLSWCD
 Molly Wick, former UMD
 Grant Neitzel, former UMD
 Megan Kelly, MN DNR
QUESTIONS
Jenny Jasperson
Watershed Unit
MPCA Duluth office
218-302-6634
[email protected]
2012 MIXING MODELS
BASEFLOW SEPARATION
May 2012 3-inch
Rain Event
Post-flood 2012
Baseflow
Snowmelt
2012
Non-flood year
Baseflow
(2010 & 2014)
Initial Township Testing
2013-2014 Results
for
Nitrate in Private Wells
The Minnesota Department of Agriculture’s
Township Testing Program
Kimberly Kaiser
Hydrologist
Nikol Ross
Hydrologist
Fertilizer Management Unit
Contributing Staff
Hydrologists
•
•
•
•
•
•
•
•
•
•
•
Nikol Ross
Jeff Paddock
Brennon Schaefer
Bill VanRyswk-Supervisor
Marie Juenemann
Katie Rassmussen
Adam McCullough
Ryan Meyer
Alicia O’Hare
Jaime Nielsen
Dylan Timm
Managers/Supervisors/
Program Administrators
• Bruce Montgomery
• Larry Gunderson
• Annie Felix-Girth-NFMP
• Heather Johnson
• Margaret Wagner
Minnesota Agriculture
•
Corn and soybeans are Minnesota’s top producing
crops
•
Nationally, Minnesota ranks 4th for corn production
and 3rd for soybean production
•
The agriculture and food industry is the 2nd largest
employer in Minnesota
http://www.nass.usda.gov/Quick_Stats/Ag_Overview/stateOverview.php?state=MINNESOTA
Minnesota Drinking Water
•
8 community water supply systems treat for nitrate
•
105 non-community system’s had water sources with
nitrate at or above the maximum contaminant level
(MCL) of 10 milligrams per liter (mg/L).
 50,000 people
 Up from 6 systems in 2008
(Minnesota Drinking Water Annual Report 2014, MDH)
The Minnesota Department of Agriculture is the state agency responsible
for nitrate in groundwater, relating to nitrogen fertilizer
Minnesota’s
Nitrogen Fertilizer Management Plan
(NFMP)
• The state’s blueprint for minimizing groundwater impacts from the use of
nitrogen fertilizer.
• 2015 revision- guided by an advisory committee
• The plan calls for an assessment of current nitrate conditions in private
wells in order to determine nitrate exceedances in drinking water at a
township scale.
NFMP Phased Approach to Regulation
Criteria
Prevention
Level One
Level Two
1.
Nitrate
Concentration
<5%
2.
BMP
Use/Adoption
Unknown
Unknown
Acceptable
Regulatory
Status
Voluntary
Voluntary
Voluntary
Level Three
5% >= 10 mg/L
or
10% >= 10 mg/L 10% >= 10 mg/L
10% >= 7 mg/L
Voluntary
Level Four
15% >= 10
mg/L
Not acceptable Not acceptable
Regulatory
Regulatory
Regulatory
Township Testing Program
(2-step assessment)
This survey approach was developed with input from the advisory
committee and from years of experience with nitrate clinics and
volunteer private well networks
Step 1.
• Initial homeowner collected sample
–
Offer all well owners in the township a free nitrate test kit.
Step 2.
•
Offer follow-up sample for high (≥5 mg/L) nitrate wells
–
Collected by trained staff (with homeowner permission)
*http://www.mda.state.mn.us/protecting/cleanwaterfund/gwdwprotection
Except that:
At the direction of the Minnesota Legislature ( HF1183 Article 2, Sec. 3, part
b), Cite: Minn. Stat.; 2013 Minn. Laws Chap. 137 Art. 2 Sec. 3(b) additional
funds were appropriated:
“monitoring for pesticides when nitrate is detected”
• The MDA began sampling in September of 2014 for common detection
pesticides as a pilot project in Dakota County.
• MDA List 1 Pesticides, which is comprised of 22 pesticide-related
compounds and includes the five groundwater common detection
parent compounds.
Township Testing Program
(2-step assessment)
This survey approach was developed with input from the advisory committee
and from years of MDA experience with nitrate clinics and volunteer private well
networks
Step 1.
• Initial homeowner collected sample
–
all well owners in the township are offered a free nitrate test kit.
Step 2.
•
Offer pesticide sample and follow-up nitrate sample for wells
with detectable nitrate
•
Collected by trained staff (with homeowner permission)
*http://www.mda.state.mn.us/protecting/cleanwaterfund/gwdwprotection
Where do we start?
• Areas with a history of high
nitrate results
• Significant row crop
production and vulnerable
groundwater
• Local staff knowledge and
input
Step 1. Initial Sample
(Homeowner Collected)
• Work with local partner (SWCDs or County
environmental services) to offer free nitrate test kits
to homeowners in vulnerable townships
• The local partner responsibilities
• Develops the mailing list of private well owners
• Public service announcements/outreach/homeowner
questions
• Coordinates with a certified lab to send well owners a nitrate test
kit.
What’s in the Nitrate Kit?
Well owners receive in the mail:
• Invitation letter
• Sample bottle
• Sampling instructions
• Prepaid mailer
• Survey about their well
(construction type, depth, age and
potential nitrate sources)
Homeowners receive their results
from the lab with a brochure
discussing the results.
Cost: < $30 per well for
Administration/supplies/analysis
/data entry
Initial Data Analysis of Homeowner Collected Samples
1. Summarize results by township
2. Summarize well surveys
•
•
•
•
•
3.
Type of well construction
Well depth
Well age well
Land use
Potential nitrogen sources
– septic distances/feedlots/fertilizer storage
Summarize all relevant groundwater information
• County geologic atlas or regional aquifer assessments/nitrate probability
maps
• County well index well profile
4.
Results by aquifer (if unique ID is provided and a well log is available)
Preliminary Results
of Homeowner Collected
Samples
2013-2014
Approximate
% ≥ 10 Number of Number of
mg/L
Townships
Wells*
< 5%
14
1351
5- 9.9%
17
2334
>=10 %
29
3657
Total
60
7342
* Does not include wells of known hand
dug construction or wells with unclear
locations.
Total Samples Collected by Township
• Average
response rate is
30%
Total Samples Collected by Township
Step 2. Follow-Up Sampling
Offer all well owners with
detectable nitrate a free
pesticide sample and follow-up
nitrate sample
1.
Blue tag
Document well information
•
•
•
•
Unique well
Identification number
Well type
Well diameter
Obvious well
construction problems
Damaged
casing
Poor seal
Hand Dug Well
photo credit: MDH/SE
Network well
coordinator training
slides
Step 2.
Follow-Up Sampling
2.
Collect nitrate and pesticide
samples (MDA staff)
3.
Inventory possible nitrate sources
close to the well.
• Septic sources
– appropriate isolation distances?
• Animal sources
– animal or poultry
building/feedlot/manure
storage?
• Other sources
– fertilizer storage
Data Analysis for Follow-up Sampling
1.
Have results changed significantly since initial homeowner
sample?
2.
Does the survey information accurately reflect the well site visit
and well log information?
3.
Aquifer designation and nitrate results
Prior to Making a NFMP Level Determination
Data Must be Reviewed and Screened
1. Well Information for high nitrate wells
• Obvious well construction problems (cracked casing/ no grout/ poor
seal)
2. Screen out wells with likely point sources
• Septic sources
– appropriate isolation distances?
• Animal sources
– animal or poultry building/feedlot/manure storage?
• Other sources
– fertilizer storage
In Summary:
•
Local partners and private well
owners are the cornerstone of
this program.
•
By the year 2019, between 250350 Townships will be assessed
for nitrate conditions in private
wells.
•
Approximately 30,000
homeowners will have tested
their well for nitrate.
Questions?
http://www.mda.state.mn.us/en/protecting/cleanwaterfund/gwdwprotection/township
testing.aspx
http://www.mda.state.mn.us/chemicals/fertilizers/nutrient-mgmt/nitrogenplan.aspx
Kimberly Kaiser
Hydrologist
Fertilizer Management Unit
Minnesota Department of Agriculture
651-201-6280
[email protected]