HomeMy WebLinkAbout9A - Chloride Monitoring Progra
'-
CITY COUNCIL AGENDA REPORT
MEETING DATE:
AGENDA #:
PREPARED BY:
REVIEWED BY:
AGENDA ITEM:
JANUARY 22, 2001
9A
LANOL LEICHTY, WATER RESOURCES COORDINATOR
SUE MCDERMOTT, CITY ENGINEER
CONSIDER APPROVAL OF THE PRIOR LAKE CHLORIDE
MONITORING PROGRAM.
DISCUSSION:
HISTORY
The Prior Lake Comprehensive Lake Management Plan identifies
action steps to take toward conserving and improving lake water
quality. Action step 4-4b in the plan is:
"Research the water quality impact of using salt-filled
sand mixtures for de-icing roadways adjacent to the lake. 11
On May 15, 2000, the City Council directed the Lake-Advisory
Committee to look at the City's use of salt-filled sand on roads along
the Lake in order to protect the water quality.
CURRENT CIRCUMSTANCES
A Chloride Monitoring Program has been prepared to study the long-
term impacts chloride from road salt has on lake water quality. The
following groups were consulted for the development of the program:
Minnesota Department of Transportation (MnDOT), Prior Lake -
Spring Lake Watershed District, Blue Water Science and various
studies and articles on road salt environmental impacts.
In initial discussions, MnDOT gave the City a verbal commitment to
assist with the study by providing lab analysis of the water samples
at no cost. In addition, the Prior Lake Association (PLA) has also
volunteered to assist in the monitoring effort.
Attached is the narrative describing the proposed monitoring
program. Briefly, samples are taken once per month for 10 months
at seven designated locations. Each location will consist of a deep
and shallow sample. Staff will collect the samples, deliver them to
MnDOT or other certified testing laboratory and record the results on
a monthly basis using City equipment. Costs for the proposed
program are discussed below.
16200~sg~~\@1~f$~g,.\3R& Lake, Minnesota 55372-1714 / Ph. (612) 447-4230 / Fax (612) 447-4245
AN EQUAL OPPORTUNITY EMPLOYER
1 ..."
Tii
FINANCIAL IMPACT:
ALTERNATIVES:
G:\AgendaO 1 \Chlorideprog.DOC
ISSUES
1) Laboratory TestinQ
MnDOT is not yet sure if they will be able to provide the laboratory
analysis of the samples. The equipment MnDOT owns old and
needs to be inspected by their staff to determine its reliability and
accuracy in determining chloride content. They will be contacting the
City once it is determined whether or not they will be able to assist
with the program. Although MnDOT may provide testing at no
charge to the City, sending the samples to a private testing
laboratory may provide testing with current methods and equipment.
2) Sample Collection
Samples will be collected at seven locations as designated on the
sampling location map. In order to keep the study as accurate as
possible the location where samples are collected should be taken at
the same spot as near as possible. A water sampler is required to
obtain the deep samples. The PLA has volunteered to assist in
collecting the water samples. Because the PLA may have different
volunteers helping throughout the year, City staff will coordinate the
sample collection procedure, so that the accuracy of collection and
ease of tracking equipment can be sustained throughout the
program.
CONCLUSION
Staff believes it is appropriate for the City Council to approve the
program and direct the collection of data. After one year of
sampling, the data will be reported to City Council. Any changes to
the program or road salt application procedures can then be
discussed.
Two cost scenarios have been identified for implementing the
program. The first scenario outlines a yearly cost of $1,455.00,
assuming that MnDOT will conduct the lab analyses of the samples
and the PLA will assist in monitoring. The second scenario yearly
cost of $2,720.00, assumes that City staff alone will collect the
samples and a private company will conduct the lab analysis. There
is a one-time cost to purchase sampling equipment of $491.00. The
funding for this program will come from the Water Quality Utility
account, which has sufficient funds to pay for this project.
The alternatives are as follows:
1. Approve the Chloride Monitoring Program as presented or with
modifications.
2. Defer action on this matter pending receipt of additional
information.
RECOMMENDED
MOTION:
G:\AgendaO 1 \Chlorideprog.DOC
T- T
3. Deny this item and provide the staff with direction.
A motion and second to approve the Chloride Monitoring Program
and direct staff to begin preparation for monitoring.
REVIE.
?~ M!J~
"R8IIEWED BY
1
. 'I
. T1I:'
PRIOR LAKE
CHLORIDE MONITORING PROGRAM
Purpose
Salt applied to roadways for snow and ice control purposes enters the lake through
the storm water drainage system. Once in the lake, the chloride in the salt can
degrade water quality. To protect and preserve Prior Lake a chloride-monitoring
program is being implemented. The purpose of the study is two-fold regarding
chloride levels:
1) To assess the status and condition of the water quality; and
2) Establish a data baseline and track trends in water quality due to road salt
application.
Goal
The goal of the Chloride Monitoring Program is intended to implement the water
quality goal expressed in the Comprehensive Lake Management Plan (CLMP),
which is to: "Protect and improve water quality by reducing non-point source
pollution."
Objective
In the CLMP, the Objective 4-4b is to 'Research the water quality impact of using
salt-filled sand mixtures for de-icing on roadways adjacent to the lake.'
Often, one or two years of data will not show trends in water quality and will not
pin-point sources of pollution. Therefore, monitoring is a long-term effort.
Carefully obtained, objective monitoring is valuable to developing information
about a water body's baseline conditions.
Tracking water quality trends requires a program of scheduled water sampling at
various locations, taking the samples, evaluating selected parameters, recording,
reporting and analyzing the results. The results over time can easily show trends
and normal ranges in the water.
Regular testing is required to establish a water quality record. This baseline record
will be invaluable in the future in order to track water quality and determine if lake
water quality is degrading or improving.
I 11
I
III
Monitorine;
The monitoring program is to set priorities for establishing or improving existing
pollution controls and determine whether additional water quality management
strategies may be required to further protect the natural resources.
After each year, the Lake Advisory Committee and/or Staff will review the
monitoring program and make any suggested changes in the program to City
Council. Some of the possible changes may include the following: a different
sand/salt mixture used on City streets; different snowplowing schedule for various
streets; more or fewer water sampling locations on the lake.
Sampline; Procedure
Samples will be collected at the seven designated locations (see attached sampling
map) on a monthly basis. Shallow (1 '-2' deep) and deep (lake bottom) samples
will be collect at each location. Sampling is expected to occur year around, except
for possibly two months, near ice-on and ice-off lake conditions, when it may be
dangerous to collect samples. Bottles will be labeled before sample collection.
The label will state the location, depth of sample and date the sample was taken.
Water samples shall be collected using a vertical water bottle. Water sample will
be decanted into the bottle that has been labeled for the appropriate location. After
all samples have been collected, the will be stored in a refrigerator until they are
picked up for analysis.
Comparison of Data with Ecoree;ion Rane;es
The Minnesota Pollution Control Agency prepared a report entitled "Minnesota
Lake Water Quality Assessment Data: 2000", published October 1999. In the
appendix is a lake water quality summary of lakes by ecoregion. Prior Lake is
located in the North Central Hardwood Forests ecoregion. The summer average
Chloride (mg/l) content for lakes in this region is 4-10 (see Table 1). This
information will be used in comparing water quality data from Prior Lake with
other lakes in the same ecoregion.
Minnesota State Water Quality Standard
Minnesota State Rule 7050.0222 assigns a quality standard for Class 2A waters,
which include Prior Lake:
The chronic standard for chloride in a Class 2A water is 230 milligrams per liter.
The "chronic standard" is the highest water concentration of a toxicant to which
organisms can be exposed indefinitely without causing chronic toxicity.
If the standard is exceeded, it is considered indicative of a polluted condition
which is actually or potentially deleterious, harmful, detrimental, or injurious with
respect to the designated use.
Recordine; and Reportine;
City staffwill maintain a month-by-month report showing the date and results of
each of the samples together with data regarding the number and date of sand/salt
applications to roadways each month.
An annual report will be prepared summarizing monitoring data results for the
current year including yearly data from previous years and comparable to the
standards set forth above.
Costs
-
Two cost scenarios have been itemized for the annual cost of implementing the
chloride monitoring program. Scenario 1 assumes that the Minnesota Department
of Transportation will conduct the laboratory analysis of the samples at no cost to
the City and the Prior Lake Association will assist in sample collection. Scenario
2 assumes that City staff alone would collect the samples and that a private
company would conduct the laboratory analysis.
The project costs consist of sampling equipment, sample collection, sample
analysis, and report preparation. It is presumed that samples will be collected 10
months out of the year, assuming that two months out of a typical year ice
conditions may be unsafe to venture out on.
It is estimated that to collect all samples it will take 3 hours per month, except in
the winter it is estimated to take 4 hours per month. The winter samples will need
to be collected with the help of an ice-auger in order to drill holes through the ice.
The cost summary for the two scenarios is as follows:
Hf
I
III
SCENARIO #1 * (MnDOT Laboratory Analysis and PLA Assisted Sample Collection)
ITEM QUANTITY PRICE EXTENSION
Lab Analysis (MnDOT) l4/month x 10 = l40/year NA NA
Staff Time (Winter) 4 hrs/month @ 4 months (= 16 hrs) $32.50/hr $520.00
Staff Time (Summer) 3 hrs/month @ 6 months (= 18 hrs) $32.50/hr $585.00
Water Bottles 140 each $2.50 $350.00
TOTAL = $1,455.00
SCENARIO #2* (Private Laboratory Analysis and City Staff Sample Collection)
ITEM QUANTITY PRICE EXTENSION
Lab Analysis 14/month x 10 - l40/year $10.25 $1,435.00
Staff Time (Winter) 4 hrs/month @ 4 months (= 16 hrs) $32.50/hr $520.00
Staff Time (Summer) 3 hrs/month @ 6 months (= 18 hrs) $32.50/hr $585.00
Intern (Summer) 3 hrs/month @ 6 months (= 18 hrs) $1O.00/hr $180.00
TOTAL = $2,720.00
*There is a one-time cost for the following equipment:
Vertical Water Sampler 1 each $170.00 $170.00
8" Ice Auger 1 each $300.00 $300.00
Neoprene Gloves 1 pair $21.00 $21.00
TOTAL - $491.00
Fundin~
Funds for the project each year will come from the Water Quality budget. Sample
analysis may be provided for by the Minnesota Department of Transportation.
The Prior Lake Association will assist with sample collection and delivery of
water samples to the MnDOT laboratory.
TABLE 1
Ecoregion Lake Data Base Water Quality Summary
(Summer Average Water Quality Characteristics for Lakes by Ecoregion)
Parameter Northern Lakes North Central* Western Corn Northern
and Forests Hardwood Forests Belt Plains Glaciated Plains
Chloride 0.6 -1.2 4-10 13 - 22 11-18
(mg/l)
*Scott County is located in the North Central Hardwood Forests region.
I.i
I
1111
:E
<(
0::
(.9
o
0::
a..
(9
z
-
0:::
o
I-
-
Z
o
:E
w
o
-
0::
o
-!
:r:
()
w
~
<(
-!
0::
o
0::
c..
tJ)
z
o
-
t-
<C
(.)
o
...I
C)
Z
-
...I
D..
:E
<C
tJ)
) ")
.../~
.cL/
~:~t/-::~1
~.-
()
'\
o
:3::3:dO)lVHS
.... ><
~ ~
~ ~
a: 0
51 S
a:
~
"Gj