HomeMy WebLinkAbout03-07-2022 Council Work Session PacketCITY COUNCIL WORK SESSION AGENDA
CITY OF LINO LAKES
Monday, March 7, 2022
Community Room
5:30 P.M.
(5:30 pm) The Rookery Activity Center (visit facility)
1. Water Treatment Pilot Study, Greg Johnson and Ursinio Puga of WSB and Associates
2. WBL — Water Appropriation Permit Appeal update, Michael Grochala
3. Council Updates on Boards/Commissions, City Council
4. Adjourn
WS-1
WORK SESSION STAFF REPORT
Work Session Item No. 1
Date: March 7, 2022
To: City Council
From: Rick DeGardner, Public Services Director
Michael Grochala, Community Development Director
Re: Water Treatment Pilot Study
Background
The Minnesota Department of Health tested the City's manganese levels in each of the City's
wells as part of the EPA Unregulated Contaminant Monitoring Rule 4 (UCMR4). The water
quality testing data from MDH indicated that five of the City's six wells exceed the maximum
recommended manganese level for infants, and three of the wells exceeds the maximum
recommend level for adults and children.
On June 14, 2021, the City Council authorized WSB to complete the Water Treatment Pilot
Study to verify the effectiveness of biological filtration to remove manganese, iron, and
ammonia from the City's well water. The purpose of the study is to provide the City with critical
information that is required to design and size a water treatment plant to address the high
manganese and iron levels in its drinking water.
The attached report recommends construction of a conventional gravity filtration system using
biological filtration with an initial treatment capacity of 6,000 gallons per minute (gpm).
Biological filtration is promoted by the Minnesota Department of Health and is currently being
used by the cities of Minneapolis, St. Paul, St. Cloud, and other communities in Minnesota to
effectively treat their drinking water. Biological filtration could potentially save the City almost
$1 million in chemical costs and save millions of gallons of water over the first 20 years of plant
operation.
The next steps that were previously identified included completion of the utility rate study and a
water treatment pilot study. The Utility Rate Study was completed by Baker Tilly and accepted
by the City Council on May 10, 2021. Staff is now proposing to move forward with the design
phase for the proposed water treatment plant.
Requested Council Direction
Information only.
Attachments
1. Water Treatment Pilot Study Report
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WATER TREATMENT PILOT
STUDY REPORT
BIOLOGICAL REMOVAL OF AMMONIA,
IRON, AND MAGANESE
CITY OF LINO LAKES I ANOKA COUNTY I MINNESOTA
February 28, 2022
Prepared for:
City of Lino Lakes
600 Town Center Parkway,
Lino Lakes, MN 55014
WSB PROJECT NO. 018601-000
mum
WATER TREATMENT PILOT STUDY REPORT
BIOLOGICAL REMOVAL OF AMMONIA, IRON AND MANGANESE
AT WELL HOUSE NO. 6
FOR THE
CITY OF LINO LAKES
ANOKA COUNTY, MINNESOTA
February 28, 2022
Prepared By:
Water Treatment Pilot Study Report
Biological Removal of Ammonia, Iron and Manganese at Well House No. 6
City of Lino Lakes, MN
WSB Project No. 018601-000
wsb
February 28, 2022
Mr. Justin Williams
Public Works Superintendent
City of Lino Lakes
600 Town Center Parkway
Lino Lakes, MN 55014
Re: Water Treatment Pilot Study Report
Biological Removal of Ammonia, Iron and Manganese at Well House No. 6
o City of Lino Lakes, MN
WSB Project No. 018601-000
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Dear Mr. Williams:
m WSB is pleased to provide you with this pilot study report for the biological removal of ammonia,
iron, and manganese completed at the Lino Lakes' Well House No. 6. The assistance provided by
m city staff during the pilot study contributed to the success of the study. Staff's knowledge of the raw
N water quality conditions and commitment to conducting water testing throughout the study was
m extremely helpful.
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We appreciate the opportunity to be of assistance to the City of Lino Lakes and we look forward to
assisting you when this project proceeds to the next phase. Please feel free to contact us if you
have any questions or if you need additional information.
Sincerely,
WSB
Greg F. Johnson, PE
Director of Water/Wastewater
CERTIFICATION
I hereby certify that this plan, specification, or report was prepared by me
or under my direct supervision and that I am a duly Licensed Professional
Engineer under the laws of the State of Minnesota.
Greg F. Johnson, PE
Date: February 28, 2022 License No. 26430
Ursinio P
PE
Date: February 28, 2022 License No. 59303
Y.
Ray Theiler, PE
Date: February 28, 2022 License No. 57772
Water Treatment Pilot Study Report
Biological Removal of Ammonia, Iron and Manganese at Well House No. 6
City of Lino Lakes, MN
WSB Project No. 018601-000
TABLE OF CONTENTS
TITLE SHEET
LETTER OF TRANSMITTAL
CERTIFICATION SHEET
TABLE OF CONTENTS
EXECUTIVE SUMMARY......................................................................................................1
1. INTRODUCTION........................................................................................................ 2
1.1 Purpose of Study................................................................................................ 2
1.1 Effects of Iron.....................................................................................................2
1.2 Effects of Manganese........................................................................................ 2
1.3 Effects of Ammonia............................................................................................ 3
1.4 Goals and Objectives......................................................................................... 3
2. RAW WATER QUALITY AND TREATMENT GOALS ............................................... 4
2.1 City -Wide Raw Water Quality.............................................................................4
2.2 Well 6 Raw Water Quality and Treatment Objectives.........................................4
3. PILOT EQUIPMENT AND SETUP............................................................................. 5
4. OPERATIONAL OVERVIEW..................................................................................... 6
5. RESULTS AND DISCUSSION................................................................................... 7
5.1
Aeration Requirements...................................................................................... 7
5.2
Iron Removal......................................................................................................8
5.3
Manganese Removal.........................................................................................
8
5.4
Ammonia Removal.............................................................................................
9
5.5
Nutrient Requirements.....................................................................................
10
5.6
Miscellaneous Water Quality Parameters........................................................
11
5.7
Filter Backwash Frequency..............................................................................
11
5.8
Filter Performance Testing...............................................................................
13
5.8.1 Backwash Recovery Test......................................................................
13
5.8.2 Shutdown Recovery Test......................................................................
13
6. FINANCIAL ANALYSIS...........................................................................................15
7. CONCLUSIONS AND RECOMMENDATION...........................................................16
7.1 Performance Takeaways.................................................................................. 16
7.2 Financial Takeaways........................................................................................ 16
7.3 Recommendation............................................................................................. 16
Water Treatment Pilot Study Report
Biological Removal of Ammonia, Iron and Manganese at Well House No. 6
City of Lino Lakes, MN
WSB Project No. 018601-000
EXECUTIVE SUMMARY
The City of Lino Lakes completed a Water Treatment Plant Feasibility Study in 2020 that recommended
conducting a water treatment pilot study to test the effectiveness of biological filtration to remove
manganese from the City's drinking water. The Minnesota Department of Health (MDH) considers biological
filtration to be an efficient and effective treatment method remove a wide variety of contaminants including
manganese, ammonia, and iron.
WSB's pilot trailer was mobilized to Well House No. 6 towards the end of September 2021 to start a
biological filtration pilot study that ended on November 26, 2021. WSB's pilot skid tested two types of filter
media to identify the best media type to remove manganese biologically. Although both media types had
similar removal performance, gravity filters with silica sand and anthracite filter media are recommended
for the proposed water treatment plant since the silica sand filter had a lower rate of headloss than the
greensand filter and silica sand media is less expensive. The silica sand filter column also showed faster
performance recovery in the backwash and shutdown recovery tests. The silica sand filter produced treated
water with an average iron concentration of 0.02 mg/L, an average manganese concentration of 0.040
mg/L, and an average ammonia concentration of 0.02 mg/L, all of which are below the target treatment
goals set for this pilot study. In addition to achieving excellent removal performance, the silica sand filter
column achieved filter run times longer than one week before filter backwashing was required, which is
exceptional for water filtration.
Implementing biological filtration at the proposed water treatment plant will eliminate the need to
prechlorinate the water and to feed sodium or potassium permanganate to oxidize iron, ammonia, and
manganese. These chemicals are required in conventional filtration facilities and are costly to feed. The
reduction in chemical usage is projected to generate approximately $950,000 in operational savings over
the next 20 years when compared to a conventional filtration facility in Lino Lakes. In addition to generating
operational savings, utilizing fewer chemicals produces less processed and more sustainable water.
Based on the treatment results obtained in this pilot study and the projected operational savings, it is
recommended to design and construct a gravity filtration water treatment plant that utilizes biological
filtration to remove manganese in Lino Lakes. Data collected in this pilot study will aid in the design of the
future facility.
Water Treatment Pilot Study Report
Biological Removal of Ammonia, Iron and Manganese at Well House No. 6
City of Lino Lakes, MN
WSB Project No. 0 18601 -000 Page 1
1. INTRODUCTION
1.1 Purpose of Study
WSB was authorized to complete this water treatment pilot study as the first step to verify the effectiveness
of a full-scale gravity biological filtration water treatment plant to remove ammonia, iron, and manganese
from the City's water. Conducting this pilot study was recommended in the City's Water Treatment Plant
Feasibility Study completed in June 2020.
The MDH considers biological filtration to be an efficient and effective treatment method to remove
ammonia, iron, manganese, and other contaminants in public drinking water supplies. The purpose of the
pilot study is to provide the City with critical information that is required to design and construct a water
treatment plant if the City decides to address the high manganese levels in its drinking water. It was decided
to conduct the pilot study with groundwater pumped by Well 6 because it contains the highest levels of
manganese and iron in comparison to the City's other wells.
1.1 Effects of Iron
Iron in drinking water is regulated by the Secondary Drinking Water Standards (SDWS) set by the U.S.
Environmental Protection Agency (EPA). Unlike with the Primary Drinking Water Standards, the SDWS are
not enforced since they are not considered to be a health risk. The SDWS are guidelines to assist public
water systems in managing their drinking water for aesthetic considerations. The SDWS for iron is 0.30
mg/L. Iron concentrations above the SDWS can stain household fixtures and clothing, cause water
discoloration, coat pipes within water distribution systems, and cause unpleasant taste and odors.
Dissolved iron can be treated by oxidizing it to its insoluble form and removing it by filtration. Iron is usually
oxidized with aeration, chlorine, or a combination of the two.
1.2 Effects of Manganese
Manganese is a common, naturally occurring mineral found in rocks, soil, groundwater, and surface water.
The SDWS include a recommended limit for manganese since manganese causes physical and aesthetic
effects on drinking water such as staining, taste, and color. Manganese in water can stain laundry, cause
scaling on plumbing, and cause water to look, smell, or taste bad. Additionally, manganese can create a
brownish -black or black stain on toilets, showers, bathtubs, and sinks. The SDWS recommended limit for
manganese in drinking water is 0.05 mg/L.
The EPA is in the process of determining if a Maximum Contaminant Level (MCL) should be established
for manganese due to updated research on its health effects. As such, the EPA included manganese in the
Fourth Unregulated Contaminant Monitoring Rule (UCMR4), which requires all public drinking water
systems serving over 10,000 people and randomly selected small systems to monitor for manganese. The
EPA will also consider the health effects of manganese in their regulatory determination and evaluate
potential risks to adults, children, and infants.
The MDH, in conjunction with studies conducted by others, has determined that children and adults who
drink water with high levels of manganese for an extended period of time may experience problems with
memory, attention, and motor skills. These side effects are more acute in infants (babies under the age of
one), as they may result in long term learning and behavioral problems. Therefore, the MDH has established
a maximum recommended manganese concentration in drinking water of 0.10 mg/L for infants and 0.30
mg/L for adults and children.
Similar to iron, dissolved manganese can be treated in drinking water by oxidizing it to its insoluble form
and removing it by filtration. Manganese is usually oxidized with potassium or sodium permanganate.
However, manganese can also be removed biologically from water using naturally occurring
microorganisms.
Water Treatment Pilot Study Report
Biological Removal of Ammonia, Iron and Manganese at Well House No. 6
City of Lino Lakes, MN
WSB Project No. 0 18601 -000 Page 2
1.3 Effects of Ammonia
Many groundwater sources throughout the United States have elevated levels of ammonia due to natural
processes, agricultural runoff or animal feeding operations. Although ammonia is not currently regulated by
the EPA, elevated levels of ammonia will pose operational and health concerns if nitrification takes place
in the distribution system. Nitrification is the conversion of ammonia to nitrite and nitrate, which can lead to
potential corrosion issues, taste and odor concerns, and ultimately, elevated nitrite and nitrate levels
throughout the distribution system. Nitrite and nitrate are regulated under the PDWS since they are known
to have significant effects on human health.
Ammonia is typically treated with the formation of monochloramine and breakpoint chlorination, which
results in the removal of ammonia by a chemical reaction with chlorine. Other conventional methods to treat
ammonia include advanced oxidation, air stripping, or reverse osmosis. Similar to treating manganese,
ammonia can be removed from water biologically. Biological ammonia removal relies on naturally occurring
microorganisms to convert ammonia to nitrite and nitrate. Biological ammonia removal at the treatment
plant eliminates the likelihood of nitrification taking place in the distribution system and potentially lowers
the chlorine dosages needed to maintain adequate free chlorine residuals in the treated water.
1.4 Goals and Objectives
The main objective of this pilot study is to evaluate whether ammonia, iron and manganese can be removed
biologically without the use of prechlorination and potassium or sodium permanganate. Another main
objective of this study is to obtain data that can be used to design, construct, and operate a gravity filtration
water treatment plant utilizing biological filtration in Lino Lakes.
The specific goals of this pilot study are described below:
1. Evaluate if biological filtration can meet the treatment goals set in this study;
2. Compare the biological filtration efficiency of various types of filter media;
3. Evaluate the duration of the biological acclimation process;
4. Evaluate the dissolved oxygen concentration needed to enhance biological filtration;
5. Establish a backwash procedure that effectively cleans the biological filters;
6. Evaluate the filter runtime of each filter media type;
7. Determine if nutrients are needed to enhance the performance of biological filtration;
8. Evaluate whether microorganisms remain effective in colder water temperatures;
9. Evaluate the performance of the biological filters following a backwash; and
10. Evaluate the performance of the biological filters following a period of shutdown.
Water Treatment Pilot Study Report
Biological Removal of Ammonia, Iron and Manganese at Well House No. 6
City of Lino Lakes, MN
WSB Project No. 0 18601 -000 Page 3
2. RAW WATER QUALITY AND TREATMENT GOALS
2.1 City -Wide Raw Water Quality
The raw water pumped from each municipal well in the City of Lino Lakes was tested as part of the Water
Treatment Plant Feasibility Study completed in 2020. A summary of the raw water manganese, iron, and
ammonia concentrations in each well are shown in Table 2-1. Well 6 was used to conduct the pilot study
due to its high combined concentrations of iron and manganese.
Table 2-1. Existing Water Supply
Well
Name
Total Iron
(mg/L)
Dissolved
Iron (mg/L)
Total Manganese
(mg/L)
Dissolved
Manganese (mg/L)
Ammonia
(mg/L)
Well
N/A
N/A
N/A
N/A
N/A
Well
0.181
0.323
0.249
0.256
ND
Well
ND
ND
0.383
0.395
0.28
Well
0.105
0.084
0.086
0.093
0.21
Well
0.310
0.290
0.152
0.151
0.14
Well
0.050
ND
0.376
0.357
0.21
N/A - Not Applicable; ND - Non -Detect
2.2 Well 6 Raw Water Quality and Treatment Objectives
The raw water quality measured during the pilot study is presented in Table 2-2. Also shown in Table 2-2
are the target effluent or treatment goal concentrations for the pilot study.
Table 2-2. Raw Water Quality
Parameter
Unit
Raw Water Quality
Target Effluent
Concentration
Average
Range
Total Iron
mg/L
0.05
0.00 - 0.17
< 0.30
Total Manganese
mg/L
0.410
0.40 - 0.45
< 0.050
Ammonia-N
mg/L
0.35
0.30 - 0.40
< 0.10
Dissolved Oxygen (DO)
mg/L
1.60
0.71 - 3.20
> 4.0
Orthophosphate
mg/L
0.13
0.07 - 0.23
N/A
Total Organic Carbon (TOC)
mg/L
2.6
1.6 - 3.5
N/A
Alkalinity
mg/L CaCO3
254
252 - 255
N/A
H
SU
7.03
6.4-7.9
7.0-8.0
Temperature
Degrees F
51.6
50.2 - 53.4
N/A
Water Treatment Pilot Study Report
Biological Removal of Ammonia, Iron and Manganese at Well House No. 6
City of Lino Lakes, MN
WSB Project No. 018601-000
Page 4
3. PILOT EQUIPMENT AND SETUP
A small portion of the groundwater pumped by Well 6 was routed to WSB's pilot skid for treatment, which
was located inside the pilot trailer parked next to Well House No. 6. The treatment equipment used in the
pilot skid is described below.
Detention Basin: The first treatment unit of the pilot skid was a detention basin. Compressed air
was introduced upstream of the detention basin at various flow rates to increase the dissolved
oxygen (DO) concentration of the raw water to promote biological growth. A 30-minute detention
time was targeted in the detention basin.
Transfer Pump: The transfer pump was located downstream of the detention basin and was used
to pump water from the detention basin into the filter columns. A pressure reducing valve (PRV)
was installed downstream of the pump to maintain an optimal water pressure upstream of the filter
columns.
Media Filters: Two 6-inch diameter filter columns were operated in parallel and downstream of the
transfer pump. The filter media in Filter 1 consisted of 18 inches of silica sand and 12 inches of
anthracite, and the filter media in Filter 2 consisted of 18 inches of greensand and 12 inches of
anthracite. Both filters had an underdrain system with reverse graded gravel and torpedo sand.
Treated water from each filter was discharged near Well House No. 6.
Other Equipment: The pilot plant was equipped with flowmeters (air and water), a flow totalizer,
pressure gauges, sample taps, an air compressor, and a HACH DR900 colorimeter to test water
quality.
A flow schematic and photo of WSB's pilot trailer are shown below.
Filter 1 Filter 1
Effluent
Well 6 Raw Detention Transfer
Water � Basin � Pump
Filter 2 => Filter 2
Effluent
Figure 3-1. WSB's Pilot Trailer at Lino Lakes' Well House No. 6
Water Treatment Pilot Study Report
Biological Removal of Ammonia, Iron and Manganese at Well House No. 6
City of Lino Lakes, MN
WSB Project No. 018601-000
Page 5
4. OPERATIONAL OVERVIEW
Influent flow to the pilot skid was maintained at 1.2 gallons per minute (GPM). From there, water was
pumped into each filter at a flow rate of 0.6 GPM per filter to achieve a filter loading rate of 3.0 GPM per
square foot (SF) of filter media per recommended Ten States Standards. The above water flow rates
achieved a 30-minute detention time in the detention basin and an empty bed contact time (EBCT) of 6.2
minutes in each filter column. The filters were backwashed with raw water when a terminal headloss of 120
inches was achieved.
Following set up and staff training, this pilot study was conducted in two operational phases, the microbial
acclimation phase and the treatment efficiency phase. The microbial acclimation phase consisted of
adjusting the aeration flow rate to promote rapid biological growth. Nutrients were not required in this pilot
study as it was determined that the natural orthophosphate concentration in the raw water was sufficient to
promote biological filtration. The second phase of the study (treatment efficiency phase) started when the
filters were fully acclimated and removing the majority of the manganese. Towards the end of this phase,
biological filter performance was measured following a backwash and a 1-week shutdown period.
Regardless of the operational phase, day to day monitoring procedures and water quality sampling
remained the same throughout the study. Daily operations included monitoring the flow rates (air and water)
and water pressure. Water quality sampling consisted of testing the water at various treatment stages
throughout the pilot skid. The majority of the water quality sampling and testing was completed on site by
City staff with some samples being shipped to a certified laboratory for testing and QA/QC purposes. City
staff were also responsible for daily monitoring of the pilot skid.
Filter backwashing was accomplished using a combination of air and raw water. The duration of the entire
backwash was approximately 12 to 15 minutes (for each filter). After draining the filter columns for about a
minute, air was introduced through the underdrain system for 5 minutes. The air scouring loading rate was
maintained at 2 cubic feet per minute per square foot of filter media (CFM/SF) for the first 3 minutes and
then increased to 3 CFM/SF for the following 2 minutes. After the initial 5 minutes of air scouring, a
simultaneous air and water backwash took place for 2 minutes. During that time, the air scouring loading
rate was reduced to 1 CFM/SF and the water loading rate was maintained at 8 GPM/SF. Following the
simultaneous backwash, the filter columns were backwashed with water for a period of 4 minutes. During
the water -only backwash, the water loading rate was varied from 8 GPM/SF to 15 GPM/SF. The backwash
water flow was stopped when the filter media achieved 50-percent stratification for approximately 1 minute.
Following the backwash, the media was allowed to settle for a short period (3 to 5 minutes) to ensure that
no media was lost when normal filter operation resumed. This backwashing strategy was effective removing
particle clusters without losing a significant quantity of microorganisms. WSB staff conducted all
backwashes.
Water Treatment Pilot Study Report
Biological Removal of Ammonia, Iron and Manganese at Well House No. 6
City of Lino Lakes, MN
WSB Project No. 0 18601 -000 Page 6
5. RESULTS AND DISCUSSION
The pilot study was conducted for nine weeks beginning on September 22, 2021 and ending on November
26, 2021. The microbial acclimation phase took place over the initial three weeks and the treatment
efficiency phase continued until the study was completed. A backwash recovery test was completed during
the eighth week and a 1-week shutdown test took place during the last week of the study. Individual
treatment results are summarized in the following sections.
5.1 Aeration Requirements
Atmospheric air was fed upstream of the detention basin to promote biological growth in the filter columns
and to oxidize the dissolved iron present in the raw water. The air flow rate was optimized during the
microbial acclimation phase with the goal of maintaining a pre -filtration DO concentration of 6 to 8 mg/L and
a post -filtration DO concentration above 4 mg/L. The final air flowrate used in this study was 0.50 CFM,
which generated an air flow and water flow rate relationship of approximately 0.40 CFM/GPM (concurrent
air and water flow). It is possible that a full-scale biological filtration facility in Lino Lakes will require a lower
air to water flow rate ratio than used in this study to effectively treat ammonia, iron, and manganese. The
DO concentration change through the pilot skid is shown in Figure 5-1. As shown in the figure below, the
raw water DO concentration increased from an average of 1.6 mg/L to an average of 6.7 mg/L after aeration
and then decreased to an average of 5.9 mg/L after filtration. Both biological filters consumed a similar
amount of DO regardless of the media type.
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X
X
X
09/22/21 09/29/21 10/06/21 10/13/21 10/21 /21 10/28/21 11 /04/21 11 /11 /21 11 /19/21
Date (mm/dd/yy)
X Raw Influent O Post -Detention O Filter 1 Effluent ❑ Filter 2 Effluent
Figure 5-1. DO Concentration Change in the Pilot Skid
The DO consumed by the filters increased significantly during the treatment efficiency phase when
compared to the acclimation phase due to the larger microorganism population in the filters at that time.
Table 5-1 below summarizes the average DO consumed by the filters during both phases of the study.
Table 5-1. Changes to DO Consumption
Phase
Avg. DO Consumption
Filter 1
Filter 2
Acclimation
7%
3%
Treatment Efficiency
14%
13%
Water Treatment Pilot Study Report
Biological Removal of Ammonia, Iron and Manganese at Well House No. 6
City of Lino Lakes, MN
WSB Project No. 0 18601 -000 Page 7
5.2 Iron Removal
The iron removal results obtained in this pilot study are shown in Figure 5-2. The figure below shows the
raw water iron concentration, the effluent iron concentration (Filter 1 and Filter 2), and the effluent target
iron concentration. The iron concentration in the water was reduced from an average of 0.05 mg/L to an
average of 0.02 mg/L. Both biological filters produced similar effluent iron concentrations throughout the
pilot study. The average filter effluent concentration is approximately 93-percent below the EPA SDWS for
iron.
0.5
0.4
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0.3
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m
0.2
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C
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0.0
09/22/21
09/29/21 10/06/21 10/13/21 10/21 /21 10/28/21 11 /04/21 11 /11 /21 11 /19/21
Date (mm/dd/yy)
X Raw Influent ♦ Filter 1 Effluent ❑ Filter 2 Effluent Effluent Target Conc.
Figure 5-2. Biological Iron Removal
The iron removed by the filters increased during the treatment efficiency phase when compared to the
acclimation phase. Although Filter 2 had a better removal performance than Filter 1, the difference in
effluent iron concentration between the two filters during the treatment efficiency phase was only 0.01 mg/L.
Table 5-2 below summarizes the average iron removed by the filters during both phases of the study.
Table 5-2. Iron Removal Efficiency
Phase
Avg. Iron Removal
Filter 1
Filter 2
Acclimation
24%
32%
Treatment Efficiency
63%
82%
5.3 Manganese Removal
The manganese removal results obtained in this pilot study are shown in Figure 5-3. The figure below
shows the raw water manganese concentration, the effluent manganese concentration (Filter 1 and Filter
2), and the effluent target manganese concentration. The manganese concentration in the water was
reduced from an average of 0.410 mg/L to an average of 0.040 mg/L in Filter 1 and 0.023 mg/L in Filter 2
during the treatment efficiency phase. Although Filter 2 produced water with lower manganese
concentrations, the effluent manganese concentrations from both filters were almost identical towards the
end of the study. All effluent manganese concentrations during the treatment efficiency phase were below
EPA's SDWS for manganese and the MDH's guidance values of 0.10 mg/L for infants and 0.30 mg/L for
children and adults.
Water Treatment Pilot Study Report
Biological Removal of Ammonia, Iron and Manganese at Well House No. 6
City of Lino Lakes, MN
WSB Project No. 0 18601 -000 Page 8
0.5
0.4
M
0.0
09/22/21
09/29/21 10/06/21 10/ 13/21 10/21 /21 10/28/21 11 /04/21 11 /11 /21
Date (mm/dd/yy)
11 /19/21
X Raw Influent ♦ Filter 1 Effluent ❑ Filter 2 Effluent Effluent Target Conc.
Figure 5-3. Biological Manganese Removal
Similar to the iron removal results, the manganese removed by the filters increased significantly during the
treatment efficiency phase when compared to the acclimation phase. Filter 1 performed significantly better
during the acclimation phase, but Filter 2 ended up removing slightly more manganese than Filter 1 towards
the end of the study. Table 5-3 below summarizes the average manganese removed by the filters during
both phases of the study.
Table 5-3. Manganese Removal Efficiency
Phase
Avg. Manganese Removal
Filter 1
Filter 2
Acclimation
43%
26%
Treatment Efficiency
91 %
95%
5.4 Ammonia Removal
The ammonia removal results obtained in this pilot study are shown in Figure 5-4. The figure below shows
the raw water ammonia concentration, the effluent ammonia concentration (Filter 1 and Filter 2), and the
effluent target ammonia concentration. The filters' effluent ammonia concentrations were almost identical
towards the end of the study and all effluent ammonia concentrations during the treatment efficiency phase
were below the target effluent concentration of 0.10 mg/L. It should be noted that the raw water ammonia
concentration in Well 6 was higher than expected when compared to the water quality testing completed in
2020 as part of the City's Water Treatment Plant Feasibility Study (see Table 2-1 for the 2020 sampling
results).
Water Treatment Pilot Study Report
Biological Removal of Ammonia, Iron and Manganese at Well House No. 6
City of Lino Lakes, MN
WSB Project No. 0 18601 -000 Page 9
A
0.5
0.4
0.1
0.0
09/22/21
09/29/21 10/06/21 10/13/21 10/21 /21 10/28/21 11 /04/21 11 /11 /21 11 /19/21
Date (mm/dd/yy)
X Raw Influent ♦ Filter 1 Effluent ❑ Filter 2 Effluent Effluent Target Conc.
Figure 5-4. Biological Ammonia Removal
Ammonia is removed biologically from the water using a two-step process called nitrification. First,
Nitrosomonas microorganisms convert ammonia to nitrite, then Nitrobacter microorganisms convert nitrite
into nitrate. The effluent nitrite concentrations increase during the first step of nitrification until the
Nitrobacter microorganisms are acclimated, which usually takes 2 to 3 weeks. Due to the expected low
concentration of ammonia in the raw water, the MDH did not require monitoring for nitrite or nitrate in Lino
Lakes' study. However, since the raw water ammonia was over 0.20 mg/L, randomized testing was
completed for nitrite and nitrate by WSB staff to monitor the effluent concentrations. Effluent nitrite and
nitrate concentrations were maintained below 0.30 mg/L and around 1 mg/L, respectively, which is
significantly below the MLC established by the EPA for each contaminant. Towards the end of the study,
the nitrite concentrations were reduced to near zero and almost all the ammonia was converted to nitrate.
Filter 1 performed significantly better than Filter 2 during the acclimation phase. However, both filters
achieved similar levels of performance towards the end of the study during the treatment efficiency phase.
Table 5-4 below summarizes the average ammonia removed by the filters during both phases of the study.
Table 5-4. Ammonia Removal Efficiency
Phase
Avg. Ammonia Removal
Filter 1
Filter 2
Acclimation
50%
37%
Treatment Efficiency
94%
93%
5.5 Nutrient Requirements
Orthophosphate is a form of phosphorus that is dissolved in the water. Because it is dissolved, it is
immediately available to be consumed by microorganisms for growth. Since orthophosphate is consumed
by the microorganisms, it is important to maintain an adequate concentration upstream of the filters. The
natural raw water orthophosphate concentration from Well 6 averaged 0.13 mg/L. This concentration was
sufficient to promote rapid biological growth, so additional nutrients were not required during the pilot study.
Water Treatment Pilot Study Report
Biological Removal of Ammonia, Iron and Manganese at Well House No. 6
City of Lino Lakes, MN
WSB Project No. 0 18601 -000 Page 10
5.6 Miscellaneous Water Quality Parameters
Other parameters that were monitored during this study included alkalinity, pH, water temperature, total
organic carbon (TOC), and coliform bacteria. Water temperature and pH were tested on site while alkalinity,
TOC, and coliform bacteria samples were shipped to a certified laboratory for testing.
Alkalinity: Raw water alkalinity averaged 255 mg/L as CaCO3 during the pilot study. Biological
filtration had minor impacts on alkalinity as the effluent concentrations were maintained around 250
mg/L as CaCO3 during the treatment performance phase.
pH: Raw water pH averaged 7.0 SU during the pilot study. Effluent average pH concentrations for
Filter 1 and Filter 2 were 7.2 SU and 7.3 SU, respectively. The slight increase in pH is due to the
water being aerated. When water is aerated, it creates a turbulence which causes the dissolved
carbon dioxide (CO2) and carbonic acid in the water to outgas. Outgasification of CO2 and carbonic
acid from water results in pH increase. Effluent pH concentrations were maintained within the range
set by the treatment goals.
Water Temperature: Raw water temperature ranged from 50.2 OF to 53.4 OF and effluent water
temperatures averaged 53.9 OF. Microorganisms thrive in warmer and stable environments and the
lower water temperatures experienced during the winter months did not affect the performance of
the biological filters. Water temperature increased in the pilot skid since the ambient temperature
in the pilot trailer ranged between 50 IF and 60 IF on most days.
TOC: The raw water TOC concentration averaged 2.6 mg/L during the study. Filter 1 and Filter 2
removed on average 14-percent and 16-percent of the influent TOC, respectively. Both removal
performances are on par with results obtained in other biological filtration applications. TOC
sampling was conducted both during the microbial acclimation and the treatment efficiency phases.
Coliform Bacteria: Coliform bacteria were tested during both phases of the study. All laboratory
results, both influent and effluent, returned absent E.Coli results.
Total Trihalomethanes (TTHM): Organic carbon in groundwater is predominantly natural organic
matter, which is typically derived from living or decayed vegetation. Natural organic matter can be
present in particulate, dissolved, and colloidal forms, and it is usually assessed when TOC exists
in the raw water. Disinfection byproducts (DBPs), which are suspected by the EPA to cause cancer,
can form in the drinking water when natural organic matter is present along with chlorine. This
occurs when chlorine is added to the drinking water for treatment. Higher chlorine doses and TOC
concentrations will lead to more DBPs being formed. DBPs can be assessed based on the TTHM
concentration in the water. The MDH waived the requirement to test for TTHMs during this study
as historically, the TTHM concentrations in Lino Lakes raw water have ranged from 94-percent to
99-percent below EPA's MCL. The future TTHM concentrations in Lino Lakes are expected to be
even lower if a water treatment plant is constructed as some of the TOC in the raw water will be
removed at the treatment plant. In addition, the TTHMs should become even lower with biological
filtration since prechlorination would not be used in the filtration process.
5.7 Filter Backwash Frequency
Obstruction to water flowing through a filter increases as contaminants are removed from the water and
accumulate in the media over time. This phenomenon is referred to as headloss through the filter. Headloss
will eventually reach a point known as terminal headloss, at which time the filter must be backwashed. If a
filter does not reach terminal headloss to initiate a backwash, weekly backwashes are still recommended
to avoid channeling and breakthrough of contaminants. The terminal headloss was set to 120 inches.
It is not uncommon for conventional water filtration facilities that treat groundwater to be backwashed every
2 to 3 days. On the contrary, biological filtration facilities tend to experience longer filter run times of 3 to 7
days. Usually, the main groundwater contaminant affecting headloss buildup is iron, and water treatment
facilities with high raw water iron concentrations may have to backwash their filters as often as once per
Water Treatment Pilot Study Report
Biological Removal of Ammonia, Iron and Manganese at Well House No. 6
City of Lino Lakes, MN
WSB Project No. 0 18601 -000
Page 11
day. Backwashing impacts the production capacity of a filter as it cannot treat water when being
backwashed. Consequently, it is the goal of any utility to reduce backwashes as much as possible.
The headloss buildup in Filter 1 is shown in Figure 5-5 and the headloss buildup in Filter 2 is shown in
Figure 5-6. The pilot filters were not backwash for a period of 3 to 4 weeks at the beginning of the study to
minimize media disturbance during the acclimation phase and to analyze if terminal headloss could be
reached. However, since the raw water iron concentration was very low, the biological filters never reached
terminal headloss. Consequently, the filters were backwashed every 7 to 15 days after the first month of
the study following the procedure described in Section 4. The rate of headloss buildup was slightly higher
in Filter 2 since greensand media is smaller than silica sand media and can obstruct more water flow. Also,
headloss data collected for Filter 2 in November 2021 is inaccurate. It is suspected that media blocked the
pressure gauge pipe assembly during this month and then dislodged from the pressure gauge.
140
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20
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09/18/21 09/28/21 10/07/21 10/17/21 10/26/21 11 /05/21 11 /14/21 11 /24/21
Date (mm/dd/yy)
Terminal Headloss ♦ Filter 1 Headloss — — Backwash Event
Figure 5-5. Filter 1 Headloss
0; I I I I. I I
09/09/21 09/18/21 09/28/21 10/07/21 10/17/21 10/26/21 11 /05/21 11 /14/21 11 /24/21
Date (mm/dd/yy)
Terminal Headloss ❑ Filter 2 Headloss — — Backwash Event
Figure 5-6. Filter 2 Headloss
Water Treatment Pilot Study Report
Biological Removal of Ammonia, Iron and Manganese at Well House No. 6
City of Lino Lakes, MN
WSB Project No. 0 18601 -000
Page 12
5.8 Filter Performance Testing
The MDH biological filtration pilot protocol requires two performance tests to be completed when the filters
are fully acclimated with microorganisms. The first performance test is a backwash recovery test which is
used to evaluate the filtration efficiency of the biological filters immediately after a backwash. The second
performance test is a shutdown recovery test which his used to evaluate the filtration efficiency of the
biological filters after the filters are out of service for one week.
5.8.1 Backwash Recovery Test
It is almost inevitable that some microorganisms will be washed away when backwashing a
biological filter. Therefore, it is important to utilize a backwash strategy that effectively cleans the
filters while minimizing the loss of microorganisms. In order to assess the biological filter recovery,
water quality samples were obtained in 15-minute intervals following a backwash for 30 to 45
minutes. Prior to sampling the post backwash effluent water, the media was allowed to settle for 5
minutes in each filter. The post backwash results were compared to the pre backwash results to
determine how long it required the filter to recover its pre backwash performance. The backwash
recovery test results are summarized in Table 5-5. The backwash recovery test was completed
during the eighth week of the pilot study.
Table 5-5. Backwash Recovery Test Results
Filter
No.
Contaminant
Pre -Backwash
Conc. m /L
( 9 )
Post Backwash Conc. (mg/L)
Target Effluent
Conc. m /L
( 9 )
15-min
30-min
45-min
Iron
0.00
0.02
0.02
N/A
0.30
1
Manganese
0.029
0.032
0.032
0.023
0.050
Ammonia
0.03
0.01
0.03
N/A
0.10
Iron
0.01
0.03
0.01
N/A
0.30
2
Manganese
0.021
0.030
0.036
0.033
0.050
Ammonia
0.03
0.12
0.03
N/A
0.10
All post backwash concentrations for Filter 1 were below the target effluent concentrations set for
this pilot study within 15 minutes of conducting a backwash. The pre backwash iron concentration
was not recovered within 45 minutes of the backwash. This is not a concern as the effluent iron
concentration was maintained below the target effluent goal following the backwash.
All post backwash concentrations for Filter 2 were below the target effluent concentrations set for
this pilot study within 30 minutes of conducting a backwash. The pre backwash manganese
concentration was not recovered within 45 minutes of the backwash. This is not a concern as the
effluent manganese concentration was maintained below the target effluent goal following the
backwash.
5.8.2 Shutdown Recovery Test
Microorganisms need "food" (oxygen, nutrients, and contaminants) in order to survive. Therefore,
a portion of the microorganisms may not survive if water flow is stopped and "food" is not available.
In order to test the survivability of the microorganisms, both filters were shut down for a period of
one week. Similar to the backwash recovery test, the performance of each filter was measured
before and after the shutdown to determine the recovery time of each filter for up to 24 hours. The
shutdown recovery test results are summarized in Table 5-6. The shutdown recovery test was
completed during the last week of the pilot study.
Water Treatment Pilot Study Report
Biological Removal of Ammonia, Iron and Manganese at Well House No. 6
City of Lino Lakes, MN
WSB Project No. 0 18601 -000
Page 13
Table 5-6. Shutdown Recovery Test Results
Filter
No.
Contaminant
Pre -Shutdown
Conc. m /L
( 9 )
Post Shutdown Conc. (mg/L)
Target Effluent
Conc. m /L
( g )
30-min
1-hour
2-hour
24-hour
Iron
0.01
0.01
N/A
N/A
N/A
0.30
1
Manganese
0.017
0.092
0.023
0.022
0.026
0.050
Ammonia
0.02
0.10
0.07
0.06
0.01
0.20
Iron
0.01
0.02
0.01
N/A
N/A
0.30
2
Manganese
0.015
0.087
0.025
0.027
0.022
0.050
Ammonia
0.02
0.12
0.09
0.11
0.04
0.20
All post shutdown concentrations for Filter 1 were below the target effluent concentrations set for
this pilot study within 1 hour of re -starting the filter. The pre shutdown manganese concentration
was not recovered within 24 hours of the re -startup. This is not a concern as the effluent manganese
concentration was below the MDH guidance value for infants within 30 minutes of filter startup.
All post shutdown concentrations for Filter 2 were below the target effluent concentrations set for
this pilot study within 1 hour of re -starting the filter. The pre shutdown ammonia and manganese
concentrations were not recovered within 24 hours of the re -startup. This is not a concern as the
effluent manganese concentration was below the MDH guidance value for infants within 30 minutes
of filter startup and the effluent ammonia concentration was maintained below the target treated
goal following the shutdown period.
Water Treatment Pilot Study Report
Biological Removal of Ammonia, Iron and Manganese at Well House No. 6
City of Lino Lakes, MN
WSB Project No. 018601-000
Page 14
6. FINANCIAL ANALYSIS
Instead of relying heavily on chemicals like other treatment methods, biological filtration relies on naturally
occurring microorganisms to treat water. Therefore, one of the main advantages of biological filtration is the
reduction of chemical usage which can result in significant chemical savings over time. In addition,
biological filtration produces less processed and more sustainable water due to the reduction of chemical
use. Biological filtration eliminates the need to feed chlorine upstream of the filters (prechlorination) to
oxidize iron and ammonia and the need to feed permanganate (potassium or sodium permanganate) to
oxidize manganese. Similar to conventional filtration, chlorine is still needed downstream of the filters for
disinfection purposes. In addition to chlorine, fluoride is also needed in the finished water. Orthophosphate
is sometimes also needed in the plant effluent for lead and copper corrosion control in the water distribution
system.
Figure 6-1 shows a 20-year projection of the annual water treatment chemical costs in Lino Lakes for a
conventional filtration facility and a biological filtration facility. Chemicals included in this analysis consist of
permanganate and chlorine. Fluoride and orthophosphate were not included in this analysis as both
chemicals may be needed in the same amount regardless of the treatment type used. The chemical cost
projection below includes a 3-percent inflation rate.
$90,000
$80,000
$70,000
ig� $60,000
2
U$50,000
CO
$40,000
E
U$30,000
$20,000
$10,000
2020 2022 2024 2026 2028 2030 2032 2034 2036 2038 2040
Date
Conventional Filtration Biological Filtration
Figure 6-1. Chemical Cost Projection for Water Treatment
The chemical cost projection shown in Figure 6-1 is summarized in Table 6-1 below. As shown in the table
below, biological filtration has the potential of generating almost $950,000 in chemical savings over the next
20 years by eliminating the use of permanganate and prechlori nation.
Table 6-1. Cumulative Chemical Cost Projection
Year
Conventional
Treatment
Biological
Treatment
Cumulative
Savings
2020
$ 34,405
$ 6,738
$ 27,667
2030
$ 476,597
$ 96,718
$ 379,879
2040
$ 1,192,271
$ 242,339
$ 949,932
Water Treatment Pilot Study Report
Biological Removal of Ammonia, Iron and Manganese at Well House No. 6
City of Lino Lakes, MN
WSB Project No. 0 18601 -000 Page 15
7. CONCLUSIONS AND RECOMMENDATION
The final conclusions and recommendations from this pilot study to assess the feasibility of biological
filtration as a water treatment method in Lino Lakes are summarized as follows:
7.1 Performance Takeaways
Aeration Requirements: An air flow rate to water flow rate ratio of 0.40 CFM/GPM was sufficient
to promote rapid biological growth and to maintain an effluent DO concentration above 4 mg/L.
Iron Removal: The iron concentration in the raw water was reduced from an average of 0.05 mg/L
to an average 0.02 mg/L, which is 93-percent below the EPA Secondary Standard for iron. Both
biological filters produced similar effluent iron concentrations throughout the pilot study.
Manganese Removal: The manganese concentration in the raw water was reduced from an
average of 0.410 mg/L to an average of 0.040 mg/L in Filter 1 and 0.023 mg/L in Filter 2. All effluent
manganese concentrations during the treatment efficiency phase were below EPA's Secondary
Standard and MDH's guidance values for manganese.
Ammonia Removal: The ammonia concentration in the raw water was reduced from an average
of 0.35 mg/L to an average 0.02 mg/L in Filter 1 and 0.03 mg/L in Filter 2. All effluent concentrations
during the treatment efficiency phase were below the target concentration of 0.10 mg/L.
Nutrient Requirements: The raw water orthophosphate concentration was sufficient to promote
rapid biological growth, and additional nutrients were not required during the pilot study.
Filter Headloss and Backwash Frequency: Terminal headloss was never reached during the
study and the biological pilot filters were backwashed every 7 to 15 days. The rate of headloss
buildup was slightly higher in Filter 2 when compared to Filter 1.
Filter Performance Testing: Filter performance testing determined that the effluent treatment
goals were met within 30 minutes following a filter backwash and within 1 hour following a 1-week
plant shutdown. Filter 1 recovered slightly faster than Filter 2.
7.2 Financial Takeaways
Implementing biological filtration in Lino Lakes has the potential of generating approximately $950,000 in
chemical savings over the next 20 years when compared to conventional filtration. In addition to generating
operational savings, utilizing fewer chemicals produces less processed and more sustainable water.
7.3 Recommendation
As recommended in the City's Water Treatment Plant Feasibility Study, it is recommended to design and
construct a gravity filtration water treatment plant with biological filtration in Lino Lakes given its piloted
treatment performance and projected operational cost savings. Both media types piloted exhibited similar
removal performance, headloss buildup rates, and responded similarly to filter performance testing.
However, gravity filters with silica sand and anthracite are recommended for Lino Lakes since the silica
sand filter had a lower rate of headloss than the greensand filter and should require less frequent filter
backwashing. In addition, silica sand is less expensive than greensand filter media.
Water Treatment Pilot Study Report
Biological Removal of Ammonia, Iron and Manganese at Well House No. 6
City of Lino Lakes, MN
WSB Project No. 0 18601 -000
Page 16
WS — Item 2
WORK SESSION STAFF REPORT
Work Session Item No. 2
Date: March 7, 2022
To: City Council
From: Michael Grochala, Community Development Director
Re: Water Appropriations Permit Amendments
Court Order White Bear Lake Restoration Assoc. v. Mn/DNR
Background
On August 30, 2017, the Ramsey County District Court issued a judgement regarding the
groundwater management of White Bear Lake and the Prairie Du Chien -Jordan Aquifer.
As a result, the City's Minnesota Department of Natural Resources (DNR) Water
Appropriation Permit 1985-6168 was amended to include the following requirements:
• PREPARE A PLAN TO CONVERT TO SURFACE WATER SOURCE
• ENACT AND ENFORE A RESIDENTIAL IRRIGATION BAN WHEN WHITE BEAR
LAKE DROPS BELOW 923.5
• PREPARE AN ENFORCEABLE PLAN TO LIMIT PER CAPITA WATER USE (75 GPD
FOR RESIDENTIAL AND 90 GPD TOTAL)
• REPORT ANNUALLY ON COLLABORATIVE EFFORTS WITH NE COMMUNITIES
TO MEET THE PER CAPITA REQUIREMENTS
Lino Lakes along with several other communities and private well permittees are
appealing the amendments. The contested case hearings were placed on hold pending
the outcome of the DNR's appeals process which has since been completed. The MN
Supreme Court issued a ruling in July of 2020 affirming 6 of the 7 issues. The cases have
since resumed and we a currently waiting for the court to set dates for the hearing.
In addition, the City is directly affected by other aspects of the order, including:
• A prohibition of the issuance of the new well permits within a 5 mile radius of
the lake.
• DNR is required to set a collective annual withdrawal limit for White Bear Lake
and adjust permits accordingly.
As the City Council is aware the community continues to grow in accordance with our
2040 Comprehensive Plan and consistent with Metropolitan Council forecasts. Both
residential and commercial/industrial development is taking place city-wide. Our
comprehensive water plan identifies the need to begin development of Well No. 7 in the
near future. DNR has developed a water model that they find sufficient for performing
the required analysis under the court order for new well permits. However, in light of
other requirements of the order, DNR does not believe it is likely any new permits from
the Prairie du Chien aquifer will be issued. Staff has inquired about the possibility to cap
existing well no. 2 to allow for construction of well no. 7. Proposed well no. 7 has the
potential for better water and higher production than well no. 2 resulting in a net benefit
for the city. We are also discussing with DNR the potential to use a different aquifer for
production.
Of potentially greater concern is the DNR's proposed collective annual withdrawal limit
for White Bear Lake, set at an elevation of 922 that would have significant impact on
community use. The proposed limit would result in the need to reduce current use by
approximately 40%. That would be extremely difficult to achieve for domestic
(household) use alone. This would allow for no population growth and in accordance
with the water allocation priorities established in Mn. Statutes § 103G.261, would leave
no water for other uses. These would include commercial and industrial uses.
Recognizing the significant impact of such a decision the DNR has requested a hearing
with the District Court to secure guidance regarding implementation of this order.
Additionally, Lino Lake, along with several other NE metro communities have worked
with our state legislators on a bill (SF 3055) that would:
• Allow cities within 5 miles of WBL to continue to operate under their approved
water supply plans.
• Would not allow another lawsuit under the same statutes to be initiated.
• Requires development of a work group to explore options for supply drinking
water to these communities, allowing growth, while ensuring the sustainability of
White Bear Lake.
A hearing was held before the Senate Environment and Natural Resources Policy and
Legacy Finance Committee on Monday, February 28, 2022. The committee approved
sending the bill to the Senate floor for consideration. If approved in the Senate it will be
forwarded to the House for consideration.
At this time, the City is not subject to this requirement pending completion of the
contested case hearings. However, the DNR has requested the City voluntarily
implement the ban. Given that we are reaching late fall and irrigation systems are being
winterized, we do not believe any action is necessary at this time. We will continue to
monitor the issue and determine if any action will be necessary as spring approaches.
Staff is also expecting to schedule a presentation by Mn/DNR representatives at an
upcoming work session.
Requested Council Direction
None required at this time. Staff may bring forward a resolution of support for the
legislation currently being considered.
Attachments
1. Mn. Statutes § 103G.261
MINNESOTA STATUTES 2021 103G.261
103G.261 WATER ALLOCATION PRIORITIES.
(a) The commissioner shall adopt rules for allocation of waters based on the following priorities for the
consumptive appropriation and use of water:
(1) first priority, domestic water supply, excluding industrial and commercial uses of municipal water
supply, and use for power production that meets the contingency planning provisions of section 103G.285,
subdivision 6;
(2) second priority, a use of water that involves consumption of less than 10,000 gallons of water per
day;
(3) third priority, agricultural irrigation, and processing of agricultural products involving consumption
in excess of 10,000 gallons per day;
(4) fourth priority, power production in excess of the use provided for in the contingency plan developed
under section 103G.285, subdivision 6;
(5) fifth priority, uses, other than agricultural irrigation, processing of agricultural products, and power
production, involving consumption in excess of 10,000 gallons per day; and
(6) sixth priority, nonessential uses.
(b) For the purposes of this section, "consumption" means water withdrawn from a supply that is lost
for immediate further use in the area.
(c) Appropriation and use of surface water from streams during periods of flood flows and high water
levels must be encouraged subject to consideration of the purposes for use, quantities to be used, and the
number of persons appropriating water.
(d) Appropriation and use of surface water from lakes of less than 500 acres in surface area must be
discouraged.
(e) The treatment and reuse of water for nonconsumptive uses shall be encouraged.
History: 1989 c 326 art 4 s 1; 1990 c 391 art 7 s 25; 1990 c 426 art I s 13; 1993 c 186 s 1; 2012 c 272
s 48
Official Publication of the State of Minnesota
Revisor of Statutes