HomeMy Public PortalAbout07-10-2012MEDINA
PLANNING COMMISSION AGENDA
TUESDAY, JULY 10, 2012
7:00 P.M.
CITY HALL (2052 County Road 24)
1. Call to Order
2. Public Comments on items not on the agenda
3. Update from City Council proceedings
4. Planning Department Report
5. Approval of June 12, 2012 draft Planning Commission minutes.
6. Public Hearing — Richard Cavanaugh requests a Concept Plan
Review for a potential residential subdivision on 22.86 acres
located north of Highway 55 and east of Arrowhead Drive.
7. Public Hearing — Ordinance Amendment to Chapter 8 of the
Medina City Code related to Wind Energy Conversion Systems,
solar panels, and geothermal heat sources.
8. Public Hearing Ordinance Amendment to Chapter 8 of the
9. Public Hearing — Ordinance Amendment to Chapter 8 of the
Medina City Code related to uses permitted in commercial zoning
districts.
10. Council Meeting Schedule
11. Adjourn
REPOSTED IN CITY HALL July 6, 2012
CITY OF MEDINA PLANNING COMMISSION
Meeting Minutes
Tuesday, June 12, 2012
1. Call to Order: Commissioner Charles Nolan called the meeting to order at 7:00 p.m.
Present: Planning Commissioners Charles Nolan, Robin Reid, Randy Foote, John
Anderson, Kathleen Martin (arrived at 7:07 p.m.), Kent Williams (arrived at 7:32
p.m.) and Victoria Reid.
Absent: None
Also Present: City Councilmember Elizabeth Weir and City Planner Dusty Finke.
2. Public Comments on items not on the agenda
No public comments.
3. Update from City Council proceedings
Weir updated the Commission on recent activities and decisions by the City Council.
4. Planning Department Report
Finke provided an update of upcoming Planning projects. Two ordinance
amendments and sign ordinance. City Council directed staff to conduct a study on
wind turbines within the City. This is now top of staffs priority list.
Nolan asked status of Hennepin County wind turbine and Finke explained they were
not moving forward due to lack of finances.
Anderson asked status of Holiday Station Store's blue lights. Finke explained next
month it will be discussed. Gramercy is waiting for a decision to be made.
5. Approval of the April 10, 2012 Draft Planning Commission meeting minutes.
Motion by R. Reid, seconded by Martin, to approve the April 10, 2012 minutes
with revisions. Motion carried unanimously. (Absent: Williams)
6. Public Hearing — U.S. Home Corporation, Lennar, requests a PUD General Plan
and Preliminary Plat for 118 Single Family Home lots to be located South of
Hamel Legion Park and west of Brockton Lane.
Finke presented the application by summarizing the project. The 60 feet to the south
of the property is an old vacated row which is part of the plat. The preliminary plat
and general plan is very similar to the second concept plan. The primary changes are
the rearrangement of a pond to save trees, but beyond that it is similar to what the
Commission saw in April of this year.
V. Reid asked where the tot lot was located. Finke said the applicant could speak
more to it, but it was located in the same location during the concept stage plan and
not to the south as recommended by the Commission in April.
Finke said the overall density was approximately 2.5 units per acre. The total lots
consisted of 95 Single Family Homes and 23 detached homes for a total of 118
residential units.
Finke reviewed streets/sewer and water. The streets would be 28 feet in width
internally with a 50 foot right-of-way. Martin asked if any right-of-way was being
dedicated on the plat and Finke said 33 feet.
Anderson asked about a letter from Loren Kohnen and his concerns for narrow street
widths in the event of emergency. He asked how concerned staff was regarding this
issue. Finke explained if people parked poorly on both sides of the street the fire
truck should still be able to maneuver into the area, though it would be slower. Three
access points into the site are available and the City would regulate the parking
requirements. Finke explained the proposed street width has become the city's new
standard, though untested.
Foote asked how our streets compare with Plymouth. Finke said he wasn't sure.
Weir asked about roadway width in Morningside and Finke said the streets are posted
no parking on both sides of the street.
Finke explained the final review criteria, stating the City has a great deal of discretion
and the applicant was seeking discretion since it's a PUD. Finke said the
Commission should always go back to the ordinance and comprehensive plan for
direction.
Nolan said he saw by the minutes that the Commission had wanted the tot lot on the
south side and questioned why the applicant hadn't moved it.
Finke explained Cherry Hill and The Enclave along the Hunter side had 5 and 10 foot
side yard setbacks.
Nolan asked about traffic site lines and said it seemed to be an issue hanging out
there. Finke explained the traffic numbers are based on a 10 second lead time to pull
out onto Brockton Lane. He said the major difference between the two is the
MnDOT standard assumes you can't do anything the first 2 seconds, so only 8
seconds would be remaining. The engineer isn't suggesting a realignment to meet the
requirement. Nolan said he assumes the traffic study looks at traffic speed levels at
40 and 50 mph. Finke said the study reviews it only at 40 mph.
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Foote was looking for clarification on the tree preservation ordinance. Finke
explained 70 percent of the significant trees will be removed. Nolan clarified the first
10 percent doesn't have a penalty. Finke said the overall removal of trees is 15
percent when combined with the initial development without a penalty. He is
planning to consult with the City's arborist. He said he is concerned with the
intensity of all the trees being proposed for long term growth and ability to survive.
He thought if there wasn't enough room within the development then possibly the
overflow could be planted in The Enclave development along Hunter Drive.
Martin asked about what setbacks were being shown on the site plan on the south
side. Finke said the homes on the site plan show them 10 feet apart, but the applicant
is proposing to have the option to be closer.
Nolan asked about the use of the building envelope. Finke said homes are typically
consuming the entire building envelope except for the larger developments such as
Foxberry and Keller.
Finke explained the Cherry Hill development had 60 foot lot frontages and the
proposed development is greater.
Joe Jablonski representing US Home Corporation said it's been a pleasure working
with planning staff to get to this point in the process so quickly.
Jablonski said in Plymouth he had developed with the same street width standards
and Plymouth allows parking on both sides. Medina is only proposing parking on one
side of the street.
Jablonski said the tot lot was proposed on the north side, so it would be in a central
location for both the Enclave and the proposed development, since it will be fairly
large with possible pool area and recreational equipment. He said Lennar's concern
is "connectivity" and to not have it imbedded into one neighborhood area.
Jablonski said Lennar would like to relocate a lot of the trees on -site, but it would
have to be done on a case by case basis while working with staff.
Jablonski said they met the minimum standards for engineering requirements in the
traffic report/study.
Jablonski said the side yard setbacks on the south end would be designed to have
consistency throughout the neighborhood.
Martin asked the applicant to walk through the PUD standards and say why he thinks
they meet the tests. Jablonski said:
Subd 1. — Innovation in development to the end that the growing demands for all
styles of economic expansion may be met by greater variety in type, design, and
placement of the structures and by the conservation and more efficient use of land in
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such developments. - Applicant — This is achieved through the blending of densities
from north to south. We are offering three distinct lot types that will allow for
multiple house types, sizes, and price points. The higher density section along the
park is designated for our Lifestyle product. The Enclave at Brockton is designed to
fulfill the void in 75 foot wide lots......
Nolan asked about the issue of a floodplain. He asked where Lennar was at with it.
Jablonski said they have been working with FEMA and they aren't doing work below
the floodplain levels, and any work would require permits.
V. Reid said she wasn't on board with the tot lot being adjacent to Hamel Legion
Park because she doesn't want the continuity. Jablonski said the area will be
marketed as one neighborhood. He said having it located on the northern end would
limit the traffic elsewhere. V. Reid doesn't like both under one HOA. She asked
how many units would be between the two developments. She calculated around 700
people. Nolan asked what other amenities would be in the HOA lot and Jablonski
said a pool, possible clubhouse building; but at a minimum it would have a building
with restrooms and some other recreation inside.
Weir asked what the concern was with the pool area on the north side. She asked if it
was because of the park. Nolan said he wasn't sure, but it needed to be discussed.
Finke said it could be moved across the street away from the public park. Jablonski
said they did look at the proposed location rather than across the street, due to trees
and that it would be shaded the majority of the time.
Nolan asked if the first two lots across the street were used for the tot lot and that the
location would actually be in the middle of the development if the two developments
were one neighborhood. Finke said he had some concern if it was moved to the
south, since it could change density.
Martin said previously during the Concept stage berming was discussed. She asked if
that was not possible and wondered if fencing was discussed as a barrier. Jablonski
said on the landscape plan they intend to make the opaque requirements. They chose
to not show berming along the south side since by not doing it a lot of significant
trees would be saved.
Nolan asked how much of the significant trees were on the Bitterman property.
Finke said there were some.
Finke said where there aren't trees they could berm and where they have trees there
would be no berm requirement. Finke said in some locations berms would push the
drainage closer to the homes.
R. Reid asked about siting the municipal well. Jablonski said they are continuing to
work with staff. He would like to get some type of credit. Finke said some of the
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well would be used for irrigation. Finke said there is space for a well location along
Brockton Lane.
Public Hearing Opened at 8:11 p.m.
Dan Cates, representing the landowners along Brockton Lane, said they felt that
Lennar was doing a good job. He said all nine landowners were under contract with
Lennar.
Public Hearing Closed at 8:13 p.m.
HOA (tot lot area) location — Nolan summarized that he was aware the mayor had
concern with a park next to a park.
V. Reid thought two HOA's should be established rather than one.
Nolan raised concern about not having any information related to the HOA tot
lot/pool area. He is concerned with not being able to review the parking and size for
700-900 residents. The pool area is not within walking distance so it is a concern.
Martin wants the parking to be on the side of the pool. The placement and size
should be conditioned on further study. Anderson concurs with Martin and other
Commissioners. He said potential is for 800 residents at one pool. He is surprised by
only having one pool area for both projects. Foote said he would have concern with
parking and traffic at any tot lot location.
Nolan asked the applicant to provide information from other pools they have
constructed to convince them further.
Martin asked the size of the site and Finke said its 25,000 square feet. Jablonski said
he doesn't want this issue to hold up the process. He doesn't want the Commission
so concerned by it that it slows up the process. At the end of the day they could just
pull it. Nolan said it's a fair comment and is a small piece of the overall application.
Nolan suggested that maybe they shouldn't look at having the pool area amenity at
this time. He would favor the lot to be an Outlot and come back later. He said the
City should not lock themselves into approving it without details.
R. Reid said for marketing purposes does it need to be a pool that may sit covered for
a large portion of the year.
Martin said the tot lot is oversized and could only accommodate one home. She feels
it's a wise use of leftover land and has minimal impact to neighboring properties. She
thinks the location could stay where it is with conditions placed on it related to the
parking. The Commission felt it needs significant screening and separation from
other homes and parking data.
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Weir said she's been to the Bridgewater pool and hasn't seen people swimming, but
has seen towels out, but not heavily so she knows it's being used. She said she thinks
it's a great amenity.
US Home Corporation representative said Lennar will look at the pool location and
provide design.
Martin recommended additional berming on the south side of the development. V.
Reid said she lives in Foxberry Farms and the idea of a pool was considered there.
She said many Foxberry residents wished they had constructed a swimming pool
within their development. She said she thinks it is a good idea for the proposed
development to have a swimming pool as an amenity.
Nolan asked that the Commission finish discussions on a couple of other issues. He
asked the Commission what their concern was with the side yard setbacks. The
Commission recommended 10/10 for the larger lots south of the trail area.
Traffic Site lines — no concerns and recommends approval with staff's condition.
V. Reid suggested staff work with the Arborist as a condition.
Motion by Martin, seconded by Anderson, to recommend approval of the PUD
General Plan and Preliminary Plat subject to the modifications to the conditions.
Motion carried unanimously. (Absent: None)
7. Public Hearing — Henri Germain requests a Variance from the City's
requirement to install an upland buffer adjacent to a wetland required for
construction of new home at 790 Navajo Road.
Finke presented the application and explained City code requires installation of
upland buffers adjacent to all wetlands upon "new development activity."
Finke showed an aerial and reviewed the "practical difficulties" requirement and
explained the applicant had submitted a narrative explaining why he felt he had
"practical difficulties." Finke said the wetland was relatively small overall and the
upland buffer would be more than one and one half the size of the wetland. He
explained that the majority of the year the wetland was dry. He also said other
wetlands in the development don't have upland buffers.
Finke reviewed the Statutory Criteria. He said the required upland buffer didn't
appear to have impacts on the construction of the new home, but rather the concern is
aesthetics for the property owner. Staff's recommended conditions were reviewed in
case the Commission chose to approve the variance.
Martin asked what other plants could be used besides prairie grasses within the
upland buffer area. Finke said there are other options.
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R. Reid asked if trees could be planted within a buffer. Finke said it was possible if
you can sustain coverage.
Foote asked if grading would be involved and Finke said it would just be a matter of
tilling up the ground.
Henri Germain, 790 Navajo Road, wanted to thank Dusty and Deb for their help in
getting to this point in the process.
He explained the large wetland was added by the previous land owner which was a
great amenity that wasn't required at the time, though it was one of the reasons they
bought the lot. He said he wanted to make the entire area environment friendly. He
said the subject wetland had been mowed for over the past 20 years. He said it is the
buffer that creates a small issue. One of his concerns was the wood ticks within this
area if it were to be expanded. He would like this area to blend in with the
neighborhood since it is near the roadside and wanted it to be status quo. He said the
only place for a playset was along the west side of the large existing pond which was
visible from their kitchen. He explained that if the Variance was approved and the
specific conditions being recommended were placed on him he wouldn't be able to
put in their playset for his kids. He said they only have one location that would work
for a playset that is flat enough and it's the area staff is recommending for the
additional buffer area for the pond on the north side of the lot. He has tried to keep
everything the way it was when they purchased.
Germain said he has a challenge with the buffer and not the wetland. Williams asked
Germain if he had concerns with staffs conditions if approved. Germain said the
only concern is using up the area for his playset.
Public Hearing opened at 9:13 p.m.
Finke said staff isn't really recommending approval of the Variance. R. Reid asked if
the buffer could be reduced. Finke said it's the existence of the buffer, though
Germain said he would consider a smaller buffer if the Commission didn't choose to
eliminate the buffer all together through the variance.
Nolan said rather than looking at it partially dry or partially wet he asked if the
applicant had thought of trying to make it into something nice. Germain said he
knows it's possible to make a nice amenity out of the buffer area but said it's an
investment of time that he doesn't have.
Williams asked about staffs condition that would take away his only location for a
playset, saying he would not be alright with it.
Weir suggested the Commission address the requirements of a Variance.
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Nolan said when taking the Variance criteria literally he was having a hard time with
justifying approval. He said precedence is always a concern for him. He doesn't see
the hardship and feels that by having less of a yard area for kids to play in isn't a
reason for approval of a Variance. Williams said it appears to be more of an aesthetic
concern by the applicant and felt there would be a huge variety of choices that could
be low maintenance for the required buffer area. Nolan said not all vegetation is
difficult to maintain.
Finke asked the Commission if they felt there were issues with the ordinance that was
recently approved. The Commission commented that they didn't think there were
issues. R. Reid said she didn't think the application qualified for a Variance.
R. Reid said the adjoining wetland to the west looks nice and suggested doing
something similar to it to blend the two wetlands.
Public Hearing closed at 9:34 p.m.
Motion by Williams, seconded by V. Reid, to recommend denial of the application
based on the findings described in the staff report.
Motion carried unanimously. (Absent: None)
8. City Council Meeting Schedule
Finke requested a Commissioner attend the June 19th City Council meeting.
Anderson said he would attend the next council meeting.
9. Adiourn
Motion by Williams, seconded by R. Reid, to adjourn at 9:27 p.m. Motion carried
unanimously. (Absent: None)
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Agenda Item: 6
MEMORANDUM
TO: Planning Commission
FROM: Dusty Finke, City Planner
DATE: July 5, 2012
MEETING: July 10, 2012 Planning Commission
SUBJ: RPC Medina, LLC — Concept Plan for residential development —
N of Hwy 55, East of Arrowhead Dr. — Public Hearing
Review Deadline
Complete Application Received: June 20, 2012
Review Deadline: August 19, 2012 (60 -day)
Summary of Request
RPC Medina, LLC has requested review of a Concept Plan for a potential residential subdivision
on approximately 23 acres (approximately 21.45 net acres) immediately west of the Fields of
Medina. The applicant has submitted a number of potential site layouts for City discussion
which show predominantly single-family development, although some of the layouts show areas
being "set aside" for a small amount of townhomes to be developed in the future. The
applicant's preference is to be able to develop the property with 75 -foot wide single-family lots,
which is the reason they have submitted the Concept Plan.
The property is guided Medium Density Residential and requires a net density of 3.5-6.99
units/acre. This land use was changed from Mixed Use to Medium Density Residential at the
end of 2010 at the request of the property owner. The applicant's conceptual 75 -foot single-
family layout would achieve a net density of approximately 3.12 units/acre, assuming the City
required the 2 acres of park dedication which the applicant is showing on the concept plan.
The property is currently fanned. There are two wetlands located on the property and a wooded
area of approximately 2 acres in the northwest corner of the property. An aerial of the site can be
found at the top of the following page.
Comprehensive Plan
As mentioned previously, the property is guided Medium Density Residential. The
Comprehensive Plan defines MDR as follows:
Medium Density Residential (MDR) identifies residential land uses developed between 3.5
units per acre and 6.99 units per acre that are served, or are intended to be served, by urban
services. The primary uses in this designation will be a mix of housing such as single family
residential, twin homes, town homes, and row homes. This designation provides a transition area
between the commercial and retail uses along the TH 55 corridor and the single-family uses.
RPC Medina, LLC Page 1 of 7 July 10, 2012
Concept Plan Review Planning Commission Meeting
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The various layouts submitted by the applicant would achieve the following densities, assuming
the City requires the 2 acres of park dedicat.on shown on the concept plan:
# of Lots
Net Density
All 75' -wide single-family
60
3.12
All 70' -wide single-family
64
3.32
All 65' -wide single-family
67
3.48
The Comprehensive Plan establishes 21 objectives for Residential Uses served by urban services.
The following are the objectives staff found most relevant, and the entire list can be found on
pages 14 and 15 of Chapter 5.
• Consider exceptions to or modifications of density restrictions for developments that
protect the natural features or exceed other standards of the zoning district.
• Allow for a variety of housing types with a range of economic affordability in the urban
residential areas.
• Encourage a controlled mix of densities, housing types, age groups, economic levels, lot
sizes, and living styles that are of appropriate scale and consistent with appropriate land
use, market demands, and development standards.
• Require standards for site improvements that ensure compatibility with adjacent
residential areas.
• In urban residential zones with sanitary sewer service permit higher density in PUD's in
exchange for (1) reduced land coverage by buildings, (2) provision of more multi -family
units; and, (3) sensitive treatment of natural resources.
RPC Medina, LLC Page 2 of 7 July 10, 2012
Concept Plan Review Planning Commission Meeting
In order for the property to be developed with only wider (70'+) single-family lots, a
Comprehensive Plan amendment would be necessary.
Staff is concerned that changing the land use of the property may result in a reduction of housing
diversity by allowing more lower density single-family development. The various layouts shown
seem to show a lot of flexibility in developing the property and still being able to achieve the
required density.
It should be noted that the City is required to maintain a net density of 3-5 units/acre within the
Metropolitan Urban Service Area (MUSA). The Comprehensive Plan currently states that the
City is planned to be 3.01 units/acre, if all future development occurs at the minimum density.
Changing the future land use of this property from MDR to LDR would reduce the density to
3.00 units/acre. While this may be permissible in this context, the policy question may be why
would the City wish to reduce the density in this location as opposed to any other MDR or Mixed
Use property.
Proposed Site Layout
The concept plan shows a general arrangement which is fairly consistent through all of the
layouts. Street arrangement and grading plans have not been submitted, so a more fully -designed
plan will need to change when an actual development plan is being contemplated. The layouts
are provided more to provide context to discuss the land use of the property. Although house
pads and setbacks are not shown, they would be required to meet the standards to the R2 zoning
district unless the property was developed through a PUD. The 65' wide lots are smaller than the
required minimum lot size required by the R2 zoning district. The Planning Commission should
discuss if this is acceptable in support of higher density because developing the property in such
a way would require a PUD. Following is a summary of the requirements of the R2 zoning
district compared to the layouts in the concept plan:
R2 Requirement
Shown on Layouts
Minimum Lot Size (single-family)
8,000 square feet
65'wide lots = 7,475 square feet
70' wide lots = 8,050 square feet
75' wide lots = 8,625 square feet
Minimum Lot Size (two-family)
5,000 square feet per unit
N/A
Minimum Lot Width
60 feet
Varies by layout
Minimum Lot Depth
90 feet
115 feet
Front Yard Setback
25 feet
Front Yard Setback (garage)
30 feet
Side Yard Setback (combined)
15 feet (10 & 5)
Side Yard (corner)
25 feet
Rear Yard Setback
25 feet
Max. Hardcover
50%
Even though it is difficult to provide feedback on the proposed layout because of how conceptual
the plans are, the Concept Plan provides the Planning Commission and City Council the
opportunity to provide comments to guide the creation of a future development plan. Generally,
staff provides the following comments with relation to the general layout:
RPC Medina, LLC
Concept Plan Review
Page 3 of 7
July 10, 2012
Planning Commission Meeting
1) A 60 -foot wide strip of property is located immediately to the west of the subject
property which includes a driveway for the two properties to the north. It is likely that
this strip of property would be included with development of either the subject property,
or the property to the west.
2) The applicant shows two access points to Meander Road for the subdivision. These
locations will need to be analyzed as part of the future application, especially how the
western access point will interact with the small area of developable property to the west
of the subject property. Staff believes a broader examination of the access is necessary
and that it likely makes sense to limit the number of access points to Meander Road to
two for all property between the park and the large wetland located on the property to the
west. Staff recommends considering a requirement for right-of-way to connect with the
property to the west. Perhaps only one entrance is necessary for this subdivision with the
expectation that a second access point would be located on the property to the west and
that the two projects would connect.
3) The applicant shows a connection to the property to the north, which is an important
consideration and makes sense from a broader traffic perspective.
4) The layout/orientation of lots with relation to Meander Road should be reconsidered in
order to reduce the "wall of homes" which would appear.
5) The Planning Commission and City Council may wish to discuss the size of the lots
shown. The 65' -wide lots are smaller than would be required by the R2 zoning district
and would need to be developed through a PUD. If the City is not supportive of this, it
would probably be in the applicant's interest to know as early as possible.
6) The depth of the lots along Meander will need to be analyzed to verify that there is
enough space to accommodate the 30 foot front setback, 35 foot setback from Minor
Collector roadways and also any necessary screening and berming.
Wetlands
Two wetlands have been delineated on the property. The applicant proposes to fill the smaller of
these basins in its entirety (located just north of Meander Road and west of the proposed eastern
access point). The larger wetland would be located between a row of homes and the property
proposed to be dedicated as park and combined with the parkland dedicated from the Fields of
Medina. Any impacts will need to reviewed for consistency with the Wetland Conservation Act,
including any required mitigation.
Streets
The applicant proposes a right-of-way width of 50 -feet internally and 60 -feet for Meander. This
is consistent with The Enclave and The Fields of Medina, but will need to be analyzed in relation
to streets and utility when the plans are prepared to more detail. More than 60 -feet may be
necessary for Meander in order to accommodate turn lanes. The concept plan shows all of the
right-of-way for Meander Road being dedicated from the property to the south. This property is
owned by another LLC linked to the Cavanaugh family. Future development proposals will need
to show that the owner is willing to dedicate this property. Any future application for
development would be expected to construct Meander Road at the developer's cost, including
any turn lanes necessary to serve this site taking into consideration all surrounding development.
A traffic study will need to be completed to verify if additional improvements will be necessary
at Arrowhead or County Road 116.
RPC Medina, LLC Page 4 of 7 July 10, 2012
Concept Plan Review Planning Commission Meeting
Sewer/Water
The concept plan shows sewer and water mains being extended to Arrowhead Drive and the
watermain being connected to the main being installed as part of the Fields of Medina. These
improvements will need to be completed at the cost of a future applicant for development and
shall be sized according to the sewer and water plans in the City Comprehensive Plan.
The City Engineer has provided additional comments, which are attached. Most notably,
sanitary sewer manholes should not be located within streets to the extent possible.
The City recently analyzed future City Water Supply capital needs and identified the area north
of Highway 55 between Arrowhead Drive and County Road 116 as a potential location for a
future water tower. The City Council may wish to discuss the potential at this site.
Stormwater/LID Review/Tree Removal
Because this is a concept plan, the applicant has not submitted drainage calculations. The plan
identifies conceptual stormwater pond locations, but does not identify improvements which
would meet the City's volume control requirements. Future development plans should include
calculations to show that proposed improvements are consistent with the City's Surface Water
Management Plan and Stormwater Management ordinance and meets volume control and rate
control standards.
Public Works and the City Engineer strongly recommend that the City require a separate pipe
system into which foundation draintiles can discharge.
No information is provided related to the conceptual grading of the site. This will need to be
reviewed at the time of a future development proposal. Grading will likely impact a vast
majority of the trees in the northwest corner of the site if the property is developed as shown in
the layouts. Tree removal for initial site development cannot exceed 10% of the total significant
trees and a large amount of replacement will be necessary if many of these trees are removed.
Staff recommends measures to save as many of these trees as possible, perhaps by avoiding
development of this area as part of the flexibility within a PUD.
Buffer Yards and Landscauing
The concept plan submittal did not include substantial information related to landscaping.
Standard City ordinances would require two trees per single-family lot and would require
bufferyards with a 0.1 opacity along Meander Road and staff recommends a bufferyard with an
opacity of 0.3 along the park.
Park Dedication
The applicant proposes 2.2 acres of property to be dedicated on the eastern portion of the
property which could be appended to the 6 acres which were dedicated from the Fields of
Medina.
The Park Commission and City Council should discuss the amount of land necessary for the
park. The Area Study conducted in 2010 recommends a 10 -acre park. 10 -acres is likely too
RPC Medina, LLC Page 5 of 7 July 10, 2012
Concept Plan Review Planning Commission Meeting
small for a community -wide park, so the park would be serving more of a local function. In this
case, it may be worth discussing how much additional property is desired to combine with the 6 -
acres dedicated from the Fields of Medina.
The applicant shows a trail easement connecting the neighborhood to the park on some of the
proposed layouts. The City's trail plan shows a trail corridor along Meander Road, and this trail
is being constructed along the Fields of Medina as part of that project. This trail should be
required to be continued when Meander is constructed adjacent to this property as well.
Purpose of Concept Plan Review
According to Section 825.63 and Section 825.71 of the City Code: "Concept plan review serves
as the basis for informal conceptual discussion between the city and the applicant regarding a
specific land use proposal. It is designed to assist the applicant in preparing a formal land use
application for the city's consideration. The purpose of the concept plan review is to identify
significant issues, suggest design considerations and discuss requirements of the city's official
controls. Concept plan review is optional, not mandatory, for qualified applicants. Concept plan
review is for the purpose of discussion and comment only. Any opinions, comments or
observations provided to the applicant by the city staff, planning commission or city council
shall be considered advisory only and shall not constitute a binding decision on the proposed
project. The applicant may not infer any future approval of a formally submitted land use
application based upon the concept plan review and no vested rights shall accrue as a result
thereof."
Staff Comments
Staff recommends that the Planning Commission and City Council begin by discussing the land
use of the site, as this is the primary policy question. The applicant seeks feedback if there is
support for a Comprehensive Plan Amendment to allow reduced density from the MDR.
If the Planning Commission and City Council do not support lowering the density, staff would
suggest discussing the layout options provided by the applicant. For example, one of the layouts
shows that the applicant could likely meet the density through smaller single-family lots (perhaps
63' -foot wide lots at 7,000 square feet in size) without any other type of housing. This would
require a PUD, so the Planning Commission and City Council could provide feedback whether
this lot size flexibility would be supported. Alternatively, the applicant shows other layouts
which show a combination of slightly larger lots and leave a portion of the site for future
townhome development. The Planning Commission and Council may wish to discuss if this mix
is preferable to granting flexibility on the lot size requirements of a neighborhood with all single-
family homes.
In addition to feedback on these broader land use questions, staff provided a number of
comments throughout this report, and the main points are summarized below for convenience:
1) Access points to Meander Road shall be or the subdivision be analyzed as part of the
future application, especially in relation to the property to the west of the subject
property. Right-of-way may be required to connect this neighborhood with the property
to the west.
2) The layout/orientation of lots with relation to Meander Road should be reconsidered in
order to reduce the "wall of homes" which would appear.
RPC Medina, LLC Page 6 of 7 July 10, 2012
Concept Plan Review Planning Commission Meeting
3) The depth of the lots along Meander will need to be analyzed to verify that there is
enough space to accommodate the 30 foot front setback, 35 foot setback from Minor
Collector roadways and also any necessary screening and berming.
4) If future townhome development is proposed to meet density requirements, staff would
recommend that the City require these lots to be shown in the preliminary plat with far
more detail to be provided so that it can be verified that the required density can be
achieved.
5) Required width of right-of-way shall be studied when streets and utilities are designed,
and additional right-of-way may be necessary.
6) A traffic study shall be submitted at the time of a development proposal to determine
what improvements are necessary for Meander Road when the area is fully developed,
and if improvements are necessary at Arrowhead Drive or County Road 116 as a result of
this development.
7) If right-of-way is proposed to be dedicated from adjacent property, that property will also
need to be platted, or right-of-way will need to be dedicated through another means.
8) The site layout should be updated to save as many trees as possible in the wooded area in
the northwest portion of the site, perhaps through setting aside a contiguous area into an
outlot as part of granting flexibility for density, lot size, setbacks, etc.
Attachments
I. City Engineer comments dated 6/26/2012
2. Narrative from Applicant
3. Plans received by the City 6/19/2012
RPC Medina, LLC Page 7 of 7 July 10, 2012
Concept Plan Review Planning Commission Meeting
WSB
Engineering ■ Planning • Environmental • Construction
& & Associates, inc.
June 26, 2012
Mr. Dusty Finke
Planner
City of Medina
2052 County Road 24
Medina, MN 55340-9790
Re: City Project: Cavanaugh Property, L-12-083
WSB Project No. 02065-160
Dear Dusty:
701 Xenia Avenue South
Suite 300
Minneapolis, MN 66416
Tel: 763-641-4800
Fax: 763-541-1700
We have reviewed the Cavanaugh Property Concept Plan dated 6-19-12. The plan set includes various lot
configurations as well as a concept utility plan. We have the following comments regarding engineering matters:
• The proposed 50' right-of-way internal to the site is 10' less than the City minimum of 60'. The City
should review and decide whether the proposed 50' is adequate.
• In all concepts the existing wetland on the east side of the property is proposed to be part of platted lots.
The City should review and determine if after providing the required wetland easements the lots platted still
have enough land area to construct a house or townhome.
• It appears the southerly wetland will be filled. This work should be done in accordance with WCA rules.
• It is unclear what the purpose of the 20' trail easement shown on some, but not all, of the concepts is for.
Further clarification should be provided regarding the purpose and why it is shown only on some concepts.
• The concept utility plan shows utilities within the area where the roadway will be constructed. City
standards require manholes and gate valves to be located outside of the driven roadway.
• The proposed sewer and water mains shown on Meander Road have notes stating "+/- 1300 LF Connect to
Arrowhead Sanitary and Watermain". The plans should show how the developer will extend the sewer and
water to Arrowhead as part of this project.
• The applicant should demonstrate how they plan to construct Meander Road south of the subject property.
Please contact me at (763) 231-4865 if you have any questions.
Sincerely,
WSB & Associates, Inc.
if
Tom Kellogg
Minneapolis • St. Cloud
Equal Opportunity Employer
K.VAedi.aVR{vare P.kvdopnmt Revictvstava eugh Property L-12-Og71Cavnneugh Property Concept Plnn Review CurrnenU.doe
June 19, 2012
Mr. Dusty Finke
City of Medina
2052 County Road 24
Medina, MN 55340
Dear Mr. Finke:
Thank you for giving us the opportunity to present our vision of developing our family farm.
The farm has been in the family for over 50 year and we look forward to seeing it become a
special place for many generations of future homeowners.
We have looked at many possibilities for the development and believe the best use for it is a
development of 75' single family lots. This would produce a lower density than the 3.5 units per
acre that it is currently guided for, but slightly more than the overall 3.0/units an acre than the
overall city's density requirement. We believe this is the best use of the property for the
following reasons:
• Townhomes are not selling as they were when requirement was established;
• Developers have no interest in developing townhomes due to lack of market for this
product and high cost of developing in Medina;
• Mattamy had a contract for this property and scrapped the project after seeing the high
cost for the townhouses and lack of townhouse sales;
• We have extensively marketed the project and no developer is interested in townhomes at
this time;
• The variance between all single family homes and a mix of single family/townhomes is
negligible as detailed below.
The main advantages to the city are as follows:
• The development would provide a trunk water main loop from Arrowhead Road to
County Road 116 (currently a dead end);
• A through connection for Meander Road which will ease congestion on County Road 116
by allowing traffic to flow to Arrowhead and an existing stoplight;
• Tax revenue from the new development (higher taxes for single family homes) and
current taxes rather than some time in the future.
EVS 110250 Valley View Rd., Suite 1231 Eden Prairie, MN 55344-3534 j Phone: 952.646.0236 j Fax: 952.646.02901 www.evs-eng.com
Mr. Dusty Finke
June 19, 2012
Page 2
The following details the potential scenarios for development:
Development with only single family homes:
75' Lots: 60 single family, 0 townhomes
70' Lots: 64 single family, 0 townhomes
65' Lots: 67 single family, 0 townhomes
With Townhomes:
75' Lots: 53 single family, 16 townhomes (2.5 acre outlot)
70' Lots: 61 single family, 8 townhomes (L1 acre outlot)
65' Lots: 65 single family, 4 townhomes (0.6 acre outlot)
Also please consider that we have taken the area required for the collector road entirely from the
adjacent property to the south. Should we have taken all or part of thearea for the road from the
development, the total unit requirements would have been as follows:
Area for road ((1345*60)/43560) = 1.853 Acres
• If the total area for road would have been on the development this would result in a unit
count of 62.57/units. ((19.73 net acreage less 1.853 road)*3.5 units and acre)
• If total area for road would have been on the development this would result in a unit
count of 65.81/units. ((19.73 net acreage less .926 road)*3.5 units and acre)
All of the above calculations assume 2.2 acres for park, 1.0 acre for wetland.
We look forward to discussing this further at your convenience and appreciate your
consideration.
Best regards,
Richard Cavanaugh
Agenda Item: 7
MEMORANDUM
TO: Planning Commission
FROM: Dusty Finke, City Planner
DATE: July 3, 2012
MEETING: July 10, 2012 Planning Commission
SUBJ: Wind Energy Conversion System (WECS) Regulation Study Public Hearing
Background
The City Council directed staff to study the City's existing regulations related to WECS at the
June 5, 2012 meeting and also established a moratorium on the approval and construction of
WECS until the study is complete and any amendments deemed necessary by the Planning
Commission and City Council have been enacted.
This staff report summarizes the information studied by staff and raises a number of questions
for the Planning Commission and City Council to discuss. The attached ordinance includes a
number of potential changes to the City's existing regulations based on the information
reviewed.
Existing City Regulations
WECS are currently permitted conditionally in the Rural Residential, Agricultural Preserve,
Rural Residential -Urban Reserve, Rural Residential 1, Rural Residential 2, and Suburban
Residential districts. WECS are not currently permitted in any of the commercial, business, or
industrial districts.
In the residential districts in which they are allowed with a CUP, the following standards are
established for WECS:
(i) minimum set back from the nearest property line 150 feet or a distance equal to the height
of the tower plus one-half the diameter of the rotor, whichever is greater;
(ii) certified by a professional engineer as being of a design adequate for the atmospheric
conditions of the Twin Cities;
(iii) equipped with overspeed or similar controls designed to prevent disintegration of the
rotor in high winds;
(iv) compliance with all building and electrical code requirements of the city, the noise
regulations of the Minnesota pollution control agency and the rules and regulations of the
federal communications commission and federal aviation administration;
(v) the city council may require compliance with any other conditions, restrictions or
limitations it deems to be reasonably necessary to protect the residential character of the
neighborhood.
(vi) the maximum capacity or size of the WECS generator shall be 100 kilowatts or less;
(vii) the city hereby reserves the right upon issuing any WECS conditional use permit to
inspect the premises on which the WECS is located. If a WECS is not maintained in
operational condition or poses a potential safety hazard, the owner shall take expeditious
action to correct the situation; and
Wind Energy Conversion Systems
Page 1 of 6 July 10, 2012
Ordinance Analysis/Amendment Planning Commission Meeting
(viii) any WECS or tower which is not used for six successive months shall be deemed
abandoned and shall be dismantled and removed from the property at the expense of the
property owner.
Regulations in other Area Communities
Regulations for WECS vary a great deal in nearby developing and rural communities. The
attached table attempts to summarize the common regulations, including in which areas
(districts) WECS are permitted, what types of WECS (private vs. utility) are allowed, setback
requirements, maximum height, etc.
Setback requirements are commonly 1.1x the height of the WECS, and some of additional
minimum standards (for example, 1.lx the height, but no less than 300 feet). The districts in
which WECS are permitted and which types of WECS are permitted vary by City. In fact, some
communities do not allow WECS at all.
Also attached is the "Minnesota Model Wind Ordinance. It should be noted that the model
ordinance was put together in 2005 by a number of zoning/community development
professionals from rural counties (Pipestone, Lyon, Nicollet) in southwest Minnesota.
Public Safety Considerations
Safety should be the primary concern of the regulations. Setback requirements are one of the
most important considerations for this factor. In addition to protecting the "fall zone" of the
tower (it needs to be noted that a collapse of the tower structure is exceedingly rare), the setback
provides protection for potential for the rotor falling (still very rare, but less so than a tower
collapse. One case has been reported in Minnesota), and ice falling from the blades.
Ordinances include the requirement for both an automatic braking system as well as a manual
braking system in order to prevent the rotor from operating in high winds. Ordinances reviewed
include many requirements that licensed professionals certify to the design of a WECS, including
things such as the footing of the tower, the tower structure, protection from lightning, etc. Staff
has included all of these requirements found in other ordinances as part of the attached draft
ordinance.
Noise
Beyond public safety, staff believes that the most important thing to consider is noise. As a
result, staff reviewed a number of studies and other information about noise impacts of wind
turbines.
WECS produce sound in two ways. The equipment itself produces sound when operating,
although new technologies are trending towards magnetic drives which produce less sound than
the traditional gearboxes. Perhaps more important than the mechanical noise, the rotor blades
produce aerodynamic sound as a result of their interaction with the wind. While mechanical
sound is relatively easy to mitigate through the use of insulation, aerodynamic sound is much
more difficult. As technology continues to evolve, rotor blades are being designed to produce
less sound. In terms of decibels (dB), generally, an increase of 3 dB is difficult to notice, while
an increase of 5-6 dB is noticeable, and an increase of 10 dB is generally perceived as twice as
loud.
Wind Energy Conversion Systems Page 2 of 6 July 10, 2012
Ordinance Analysis/Amendment Planning Commission Meeting
One example of a private turbine of 39.9 kW with a magnetic drive is spec'ed to produce "50-55
dB at...100 feet." Decibels reduce with increased distance, generally 6dB each time the distance
is doubled. At a distance of 200 feet (a likely minimum setback for this scale of turbine), the
turbine would be producing 49 dB according to its specs. Larger turbines can produce around
100 dB of sound
The State of Minnesota has determined that it is considered noise pollution (for all uses, not just
wind turbines) for more than 50 dB to occur at residential property for more than 50% of any
given hour. While almost every ordinance reviewed requires that a WECS meets the state's
noise pollution standards, staff questions if this standard is sufficient, especially in residential
settings. For example, the WECS described in the previous paragraph is 1 dB below and would
meet state law. However, the noise from the WECS will occur more often. The Planning
Commission and Council should discuss if relying on the state noise regulations are sufficient.
Aerodynamic sound from wind turbines are at a low frequency which are not attenuated as well
by windows and walls. A study from the Minnesota Department of Health states that the low
frequency sound from turbines may be amplified by resonance and be accompanied by more
vibration which lowers tolerance when compared to higher frequency sound of similar intensity.
The Department of Health report summarizes two studies from Europe which concluded that
approximately 25% of residents reported annoyance when sound from wind turbines were
measured at 35-40 dB (in one study) or 40-45 dB (in another study). It should be noted that
these studies were conducted in locations with numerous wind turbines. Reported "annoyance"
from wind turbine was more likely at lower dB when compared to other sounds.
Annoyance associated with exposure to different environmental noises
50
45
m 40 Wind turbines Aircraft
0 35 1
E 30
25 1 Road traffic
ot 20 1
3 15 / Railways
10 •1
5 -.
0 r
32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70
Sound exposure (dBA)
Pedersen, E. and K.P. Waye (2004). Perception and annoyance due to wind
turbine noise —a dose -response relationship. The Journal of the Acoustical
Society of America 116: 3460. Copyright 2004, Acoustical Society of America.
Wind Energy Conversion Systems Page 3 of 6 July 10, 2012
Ordinance Analysis/Amendment Planning Commission Meeting
The Department of Health study concluded that the Minnesota 50dB nighttime standard "appears
to underweight the penetration of low frequency sound into residences" and suggest that a more
in-depth analysis of sound is necessary for turbines.
The World Health Organization recommends that ambient noise levels should be below 35 dB
for optimum sleeping conditions.
The model wind ordinance suggests a minimum setback of 750 feet from residences for any
commercial WECS (40 kW+), and the Minnesota Public Utilities Commission requires 750 feet
setback for larger commercial turbines (over 5000 kW), primarily because of noise. While the
assumption may be that larger turbine produce more noise, this is not necessarily the case
because smaller turbines tend to operate at higher RPMs. The example turbine described above
would be reduced to 37.5 dB at 750 feet. Obviously, setbacks of 750 feet (or larger) would
greatly reduce the locations in Medina where a WECS could be located. Some regulations allow
this setback to be reduced through contractual agreements with neighboring properties,
essentially easements where the neighboring property owner agrees to the impacts occurring on
the property.
Other states and countries have adopted different types of requirements related to noise. New
York, for example, requires that a wind turbine does not increase the sound by more than 6 dB
above the measured average ambient nighttime sound. Oregon limits the sound of wind turbines
to 10 dB above the ambient level. These types of regulation requires a lot of modeling. Limits
for European countries range from 35 dB to 45 dB at a "non -consenting" property line.
Shadow Flicker
Shadow flicker is another potential impact of WECS. The rotating blades rhythmically block the
sun at locations fairly distance from the WECS, especially in the morning and evening when the
angle of the sun is lower. The flicker can be annoying for neighboring property owners. The
State of Michigan requires larger setbacks from roadways so that shadow flicker does not create
a distraction. For larger turbines, a common recommendation is that turbines be setback a
minimum of 10 times the rotational diameter of the rotor in order to reduce the impacts of
flicker.
One of the local ordinances reviewed by staff includes a requirement that a "flicker study" be
conducted as part of the CUP process in order to analyze the potential impact of shadow flicker.
Computer software exists in the wind energy industry which makes this type of study fairly easy
to accomplish.
Visual Impacts
In order to access the amount of wind necessary to effectively produce electricity, WECS are
required to be taller than surrounding landscapes and tend to be located on higher topographical
locations. As a result, the turbines will be very apparent and may cause visual impacts. Such
impacts are fairly subjective, and are very difficult to quantify or qualify. Certain design aspects
may minimize the visual impacts such as: non -reflective finishes, monopole vs. lattice tower
design, and muted color requirements.
Wind Energy Conversion Systems Page 4 of 6 July 10, 2012
Ordinance Analysis/Amendment Planning Commission Meeting
Wildlife Impacts
Concern is often raised of the likelihood of WECS striking and killing birds and bats, which does
occur. Generally, studies have shown (including studies at Buffalo Ridge in Minnesota, which
showed bats were of more concern than birds) that mortality rates are not generally high enough
to cause concern, especially when compared to other hazards which kill birds on a daily basis,
especially natural predators.
Types of WECS
Some local ordinances regulate non-commercial and commercial WECS differently. Anoka, for
example, only permits larger -scale commercial WECS. Other communities prohibit WECS over
a certain capacity.
Draft Ordinance Amendment
The attached ordinance includes many of the regulations discussed in this report.
Districts Allowed
In terms of the districts in which WECS are permitted, staff included the most inclusive list as a
starting point. This will allow the Planning Commission and City Council to remove the use
from any of the districts if they see fit. As drafted, WECS would continue to be allowed in the
RR, RR -1, RR -2, RR-UR as they are already. The amendment removes WECS from the
Suburban Residential zoning district, but adds the use to the Business, Business Park,
Commercial -Highway, Commercial Highway -Railroad, Commercial -General, Rural Business
Holding and Rural Commercial Holding districts.
Minimum Lot Size
The ordinance requires a minimum lot size of 2 acres for any WECS. A WECS over 50 feet in
height requires a lot size of 10 acres or greater and a WECS over 120 feet in height requires a lot
size of 30 acres or greater.
Setback Requirements
The draft ordinance requires a minimum setback of 300 feet or 1.25x the height of the WECS,
whichever is greater. Additional setback may be necessary in order to meet the noise limitation
at the property line which is discussed later. The Planning Commission and City Council may
wish to discuss removing the 300 foot minimum setback for smaller WECS (vertical axis
turbines under 50 feet in height, for example).
Maximum Height
The draft ordinance does not establish a maximum height for a WECS. As mentioned above,
larger lots are required for turbines over 120 feet.
Tower Design
The draft ordinance requires all WECS towers to be of monopole design. It is suggested that this
design reduces the visual impact of the tower and also the potential for impacting birdlife.
Noise
As mentioned above, staff's research has suggested that Minnesota's noise pollution standard
may not adequately protect neighboring property owners from noise impacts. Consistent with
Wind Energy Conversion Systems
Page 5 of 6 July 10, 2012
Ordinance Analysis/Amendment Planning Commission Meeting
the studies referenced, staff believes it would be best to prevent noise in excess of 35 dB from
impacting neighboring properties. This is especially true for residential property. The draft
ordinance includes language for situations where greater ambient noise is already present, which
would allow more than 35 dB of noise, but no more that 6 dB additional.
Technical Design Requirements
As referenced earlier in the report, the draft ordinance includes the requirements for professional
certifications and references to other relevant codes which were found in most other local codes.
Attachments
1. DRAFT ordinance
2. Minnesota Model Wind Ordinance
3. Study from Minnesota Department of Health
4. Summary of Regulations in other communities
Wind Energy Conversion Systems Page 6 of 6 July 10, 2012
Ordinance Analysis/Amendment Planning Commission Meeting
CITY OF MEDINA
ORDINANCE NO.
AN ORDINANCE REGARDING REGULATIONS OF WIND ENERGY CONVERSION
SYSTEMS; ADDING SECTION 828.##; AMENDING SECTIONS 826.26.4, 826.98,
832.1.03, 832.2.03, 832.3.09, 833.03, 833.07, 838.1.03, 838.2.03, 838.3.03, AND 838.5.08.
The City Council of the City of Medina ordains as follows:
SECTION I. Section 826.26.4, Subd. 8 of the code of ordinances of the city of Medina is
amended by adding the underlined language and deleting the stricken language as follows:
Section 826.26.4. (SR) Conditional Uses. Within the Suburban Residential district, no structure or
land shall be used for the following uses except by conditional use permit:
Subd. 8. Windmills er wind energy conservation sy:;tems. RESERVED
SECTION II. Section 826.98, Subd. 2(e) of the code of ordinances of the city of Medina is
amended by adding the underlined language and deleting the str-ic-keri language as follows:
Section 826.98. Conditional Use Permit Standards for Agricultural Preservation and
Residential Districts.
Subd. 2. Specific Standards. In addition to the general standards specified in section 825.39
of this ordinance, no conditional use permit shall be granted unless the city council
determines that all of the specific standards contained in this subdivision will be met:
(e) private use of windmills or Wind Energy Conversion Systems (WECS): windmills and
WECS shall he regulated as per Section 828.XX of the Medina code of ordinances.
(i) minimum set back frem the nearest property line 150 feet or a distance equal to the
height of the tower plus one half the diameter of the rotor, whichever is greater;
(u) c. titied by a professional engineer as being of a design ad. quite for the
at.,,... .,h.,t:,.
the rotor in hieh winds;
1
limitations it deems to be reasonably necessary to protect the residential character of
SECTION III. New Code Section 828.XX is added as follows:
Section 828.XX Wind Enerav Conversion Systems WECS
Subd. 1. Purpose. The purpose of this ordinance is to establish standards and procedures for
Wind Energy Conversion Systems (WECS) through a conditional use permit in order to
harness clean, renewable wind energy while at the same time protecting public health, safety
and welfare.
Subd. 2. Definitions. The following words and terms, wherever they appear within this
ordinance, are defined as follows:
(1) WECS height — the distance measured from the grade of the WECS to the highest point
of the rotor blade_ For WECS which are attached to a structure, the height shall be
measured from the lowest grade of the structure on which the WECS is attached.
Subd. 3. Location Requirements. The following shall apply to all WECS:
(a) Minimum lot size: Two acres
50 feet in height shall onlv be permitted if a lot is 10 acres in size or greater and a WECS
greater than 120 feet in height shall only be permitted if a lot is 30 acres in size or
greater_
(b) Maximum WECS density: 1 per lot
(c) Setback from all property lines and/or public right-of-ways: 300 feet or tunes the
height of the WECS. whichever is greater.
(d) Setback from all stntctures: A distance ectual to the height of the WECS. This provision
shall not apply to structures related to the operation of the WECS, nor if the WECS is
attached to a structure.
(e) No WECS shall be allowed within the Shoreland Overlay District or a tloodplain.
(t) No portion of the WECS. including the full arc area created by the bladesshall extend
over above -ground power lines or into any drainage and utility easement_
(e) For pole -mounted WECS, the full arc area created by the blades shall have 30 feet of
clearance from any accessory structure or tree.
Notwithstanding this re
uirement. a WECS greater than
Subd. 4. WECS Standards. The following shall apply to all WECS:
(a) Maximum WECS heights:
Comment [dfl]: Could set a maximum allowed
capacity (5 megawatts,
Comment [df2]: Or 5 acres
Comment [df3]: Or 1.1
Comment [df4]: Or 300 feet, whichever is
greater
Comment [DM: Option: Maximum height even
for barge lots. Option: Maximum rotor diameter!
Option: differentiate between residential and
commercial property for larger turbines
(1) WECS on property less than 10 acres in size: A 'WECS located on a property less
than 10 acres in size shall not exceed 50 feet in height.
(2) WECS on property less than 30 acres in size: A WECS located on a property less
than 30 acres in size shall not exceed 120 feet in height.
(b) Tower Design: AVFCS shall he constructed in a monopole design and shall be self-
supporting without the use of guy wires or similar features.
(c) Tower Appearance: the following provisions shall apply to WECS unless otherwise
required by FAA regulations:
(1) Towers shall be unobtrusive in color such as pale gray or white or a color consistent
with the surrounding area.
(2) Towers shall he non -reflective and/or galvanized finish to reduce visual impact.
(d) Tower Access: WECS shall he designed to prevent climbing from within 12 feet of the
,round.
(e) Controls and Brakes: WECS shall he equipped with both a manual braking device as
well as an automatic device capable of stopping the WECS operation in winds in excess
of 40 MPI-t.
(1) Lighting: No lighting, reflectors, flashers, or other illumination shall be affixed to the
WECS except as required by FAA regulations. All other on -site lighting shall he
consistent with the Medina Lighting Ordinance.
(g) All power lines and wires serving the WECS shall he buried.
(h) Electromagnetic Interference: WECS shall he filtered, shielded, or otherwise designed
and constructed so as not to cause communication signal interference. The applicant
shall notify all communication tower operators within two miles of the proposed WECS
location prior to application to the City for conditional use permit approval. The City
may require a study of the signal prior to construction in order to provide a baseline.
(i) WECS foundations shall be designed to resist two times the wind uplift calculated
pursuant to the Uniform Building Code.
(j) Noise: The WECS shall he designed and located in such a way that no more than 35
d13(A) of noise is apparent at the property line. Notwithstanding the above, the apparent
noise from the WECS may exceed 35 dB(A) at a property line if the applicant can
demonstrate that the amount of noise when the WECS is operating will not exceed the
average nighttime ambient noise by more than 6 dB(A).
(k) Manulhcturer Warranty: The applicant shall provide documentation from the
manufacturer that the WIiCS equipment proposed has been successfully operated in
atmospheric conditions similar to those within the City. The WECS shall he warranted
against any system failures reasonably expected in severe weather conditions.
(1) Certification:
(1) Equipment shall he certified by the manufacturer that it is in conformance to
applicable industry standards for wind turbine design and standards adopted by the
American Standards Institute (ANSI).
(2) An engineer registered with the State of Minnesota shall certify that the design
construction and operation of the tower and foundation are compatible with and
appropriate for the turbine to he installed given the soil and climate conditions of
the proposed location.
3
(m)Compliance with Codes: all WECS equipment shall be certified by relevant
professionals that it is in compliance with all applicable local, state, and federal
regulatory standards, including but not limited to:
(1) The relevant standards of the City Code -
(2) Uniform Building Code as adopted by the State of Minnesota -
(3) The National Electrical Code as adopted by the State of Minnesota -
(4) 'Ihe National Electric Safety Code;
(5) Federal Aviation Administration and Minnesota Department of Transportation
requirements: and
(6) Minnesota Pollution Control Agency and Environmental Protection Agency
regulations.
Subd. S. Additional Submittal Requirements. In addition to the information required
elsewhere in the City Code, applications for \VFCS shall include the following infornation:
(1) A copy of the review response from the FAA concerning the development application
and FAA requirements for warnin devices heioht restrictions etc.
(2) Technical specifications of the WECS including, but not limited to: type, height, blade
length, operating parameters, anticipated noise level at property lines, lightening
protection, manufacturer's certification as required by this section, and engineer's
certification as required by this section.
(3) A shadow flicker report summarizing the amount of time which shadow flicker will
impact neighboring property.
(4) A Decommissioning Plan as required by this section shall be submitted for review and
approval of the City.
Subd. 6. Decommissioning. AWECS shall be considered a discontinued use after six months
without energy production. A discontinued WECS must he dismantled and removed, at the
property owner's expense, within 90 days of discontinuation. The decommissioning plan
shall he reviewed and approved by the City to ensure the safe, rapid, and complete removal
of the WECS. The plan shall identify the financial resources which will he available to pay
for the im lementation of the decommissioning plan. A discontinued WECS which is not
dismantled and removed within 180 days shall he considered a public nuisance subject
abatement as described in the City Code and Minnesota law.
Subd. 7. Record Keeping. The party responsible for operating the WECS consistent with the
conditional use permit and other relevant operating standards shall measure the enerw
produced by the WECS and he prepared to report the production upon request of the City. If
records of energy production are not provided when requested, the WECS shall he
considered to not he producing energy and subject to the rec uireunent of being
decommissioned.
Subd. 8. Inspection. The City reserves the right, upon issuance of a conditional use permit, to
inspect the premises on which the WECS is located for compliance with this ordinance, the
conditions set forth on the conditional use permit, and other relevant requirements. If a
WECS is not maintained in operational condition or poses a potential safety hazard, the
4
owner shall be required to take expeditious action to correct the situation upon written notice
from the City.
Subd 9. Enforcement. Operation of a WECS in violation of the requirements of this ordinance,
of the teens of the conditional use permit, or of other relevant requirements shall he a
violation of this ordinance and subject to prosecution. Additionally, such operation shall
constitute a public nuisance, subject to abatement as described in the City Code and
Minnesota law.
SECTION IV. Section 832.1.03 (11) of the code of ordinances for the City of Medina shall be
added by adding the underlined material as follows:
,Section 832.1.P, (BPl conditional >4jsel. Within the Business Park District, no structure or
land shall be used for the following uses except by conditional use permit, the specific
requirements established in Section 832.3.09, and other applicable provisions of the city code:
(11) Wind 1?nerg,y Conversion Systems (WECS)
SECTION V. Section 832.2.03 (18) of the code of ordinances of the City of Medina shall be
added by adding the underlined material as follows:
Section 832.2.03. (B) Conditional Uses. The following shall be permitted uses within the B
district, subject to conditional use permit approval, the specific requirements established in
Section 832.3.09, and other applicable provisions of the city code:
(18) Wind Energy Conversion Systems (WECS)
SECTION VI. Section 832.3.09, Subd. 25 of the code of ordinances of the City of Medina shall
be added by adding the underlined material as follows:
Section 832.3.09. Supplemental Requirements for Specific Uses within the Business Park and
Business Districts.
Subd. 25. Wind Energy Conversion Systems (%VECS) - shall meet the requirements set
forth is Section 828.#n of this code.
SECTION VII. Section 833.03 (17) of the code of ordinances of the City of Medina shall be
added by adding the underlined material as follows:
Section 833.03. Conditional Uses. Within the Industrial Park District, no structure or land shall
be used for the following uses except by conditional use permit.
5
(17) Wind Energy Conversion Systems (WECS)
SECTION VIII. Section 833.07 Subd. 3 (q) of the code of ordinances of the City of Medina
shall be added by adding the underlined material as follows:
Section 833.07. Design and Development Standards. Design and development standards are
established for this district to achieve a high standard of development by providing assurance
that land uses, buildings, and functions are compatible within the district and with adjacent
districts. The plans and the proposed use of a property shall conform to the design and
development standards prior to approval of any permit. The applicant or owner shall supply
plans and data necessary to demonstrate such conformance.
Subd. 3. Design and development standards — conditional uses: The following design
and development standards are identified for the uses listed below. Additional standards
may be identified during the review and approval process, due to the particular
characteristics of each site, the proposed development of the site, and the uses on adjacent
property.
fq) Wind Energy Conversion Systems (\VECS) - shall meet the requirements set forth
is Section 828.# of this code.
SECTION IX. Section 838.1.03(11) of the code of ordinances of the City of Medina shall be
amended by adding the underlined material as follows:
Section 838.1.03. (CH) Conditional Uses. The following shall be permitted within the CH
district, subject to conditional use permit approval, the specific requirements established in
Section 838.5.08, and other applicable provisions of the city code:
(1 l) Wind Energy Conversion Systems (WECS)
SECTION X. Section 838.2.03 (1 1) of the code of ordinances of the City of Medina shall be
added by adding the underlined material as follows:
Section 838.2.03. (CH -RR) Conditional Uses. The following shall be permitted within the CH -
RR district, subject to conditional use permit approval, the specific requirements established in
Section 838.5.08, and other applicable provisions of the city code:
(I 1) Wind Energy Conversion S stems WECS
SECTION XI. Section 838.3.03 (10) of the code of ordinances of the City of Medina shall be
added by adding the underlined material as follows:
6
,a1
Section 838.3.03. (CG) Conditional Uses. The following shall be permitted uses within the CG
district, subject to conditional use permit approval, the specific requirements established in
Section 838.5.08, and other applicable provisions of the city code:
(10) Wind Energy Conversion Systems (WECS)
SECTION XII. Section 838.5.08, Subd. 20 of the code of ordinances of the City of Medina shall
be added by adding the underlined material as follows:
Section 838.5.08. Supplemental Requirements for Specific Uses within Commercial Zoning
Districts. In addition to the general standards specified for conditional uses in section 825.39 of
the City Code and other requirements of this ordinance, the following uses shall not be permitted
unless the city council determines that all of the specific standards contained in this subdivision
will be met:
Subd. 20. Wind Energy Conversion Systems (WECS) - shall meet the requirements set
forth is Section 828.## of this code.
SECTION XIII. This ordinance shall become effective upon its adoption and publication.
Adopted by the Medina city council this _ day of , 2012.
T.M. Crosby, Jr., Mayor
Attest:
Scott T. Johnson, City Administrator -Clerk
Published in the South Crow River on the _ day of . 2012.
7
Attachment 2 - MN Model Wind Ordinance (12 pages)
Interest and development of wind energy has increased in
Minnesota, both in the volume and geographically. During the
1990's, several counties adopted wind ordinances to address local
wind development. Over time, zoning issues have arisen and it was
found that modifications to the ordinances were desired to
promote the health, safety, morals, and general welfare of the
community. To address these issues and provide consistencies
between counties in wind development, the development of a
model wind ordinance and supporting explanation document were
identified as a benefit to all Minnesota Counties who are
experiencing wind development, and to the Clean Energy Resource
Teams who advocate renewable energy development..
The Model Ordinance (attached) and supporting explanatory
document (completion anticipated in early November 2005) are
being prepared in partnership by:
• John Biren, Lyon County
• Annette Bair, Southwest Regional Development Commission
• Kyle Krier, Pipestone County
• Mandy Landkamer, Nicollet County
• Mark Lindquist, The Minnesota Project
Additional assistance is being provided by
• Jannie Hanson, Three Rivers Resource and Conservation
Development District
Wind Turbine Zoning Summary of Standards
Counties, Cities, and Townships are enabled to regulate land
under Minnesota Statutes 394 and 462 for the purpose
"promoting the health, safety, morals, and general welfare of
community"
Key Factors in Model Wind Ordinance
1) Distinguish between Commercial and Non -Commercial wind
turbines.
a. Commercial > = 40 kW (or 100 kW)
b. Non Commercial < 40 kW (or 100 kW)
c. Optional: Micro <=1 kW and short tower
2) Define Necessary Permits
a. Commercial:
i. Conditional Use Permit in Ag and Industrial Zones
ii. "Conservation" or special protection Districts — examine
purpose of the districts to determine if CUP is
appropriate.
iii. Not permitted elsewhere, including Shoreland or Wild
and Scenic River
iv. Alternatively — establish a wind energy overlay district.
b. Non -Commercial
use
of:
the
i. Permitted in Ag and Industrial Zones
ii. Conditionally Permitted in Rural (large lot) Residential,
Highway Commercial, Urban Expansion, Shoreland, Wild
and Scenic River
iii. Not -Permitted: Rural Town Site (small lot residential),
General Business,
3) Establish Setbacks
a. Commercial
i. Homes 150 feet
ii. Property lines 1.1 — 1.25 x total height
iii. Road Rights -of -Way 1 x total height
iv. Other ROWs to be considered
v. Conservation lands 600 feet
vi. Type III, IV and V wetlands 600 feet
vii. Scenic River Bluffs 500 — 1340 feet.
b. Non -Commercial
i. Property 1.1 x total height
ii. ROWs 1 x total height (or fall zone + 10')
4) Establish Safety Standards
a. Engineers Certification on system
b. 12' minimum ground clearance
c. Markings on guy cables
5) Establish Design Standards
a. Tubular towers on commercial turbines
b. White, grey or non -obtrusive color
i. Consideration for aviation warning on met towers
c. Lighting limited to FAA requirement
d. Signage limited to appropriate warnings and turbine mfg /
owner on nacelle.
e. Power lines buried
f. Power lines between projects and off -site substations buried.
g. Substations comply with essential service standards
h. Discontinued Use and Decommissioning — considered
abandoned after 1 year no production / 90 days for
removal. — Plan required
6) Establish Other Applicable Standards
a. Comply with state noise rules (50 decibels at nearest farm
house),
b. Electrical codes, and
c. FAA regulations
1) Minimize Infrastructure Impacts
a. Road damage mitigation
b. Drainage system damage mitigation
Interference — minimize or mitigate interference with electromagnetic
telecommunications.
Note: text in brackets [ ] is to note that there are some reasonable alternatives that the
local unit of government may choose in adopting an ordinance. Those alternatives are
listed but separated by a slash /. Example:
Commercial WECS: A WECS of equal to or greater than [100/40] kW in name
plate generating capacity.
This means that the local unit may prefer a larger or smaller threshold for defining
a Commercial WECs.
Wind Energy Conversion System Ordinance
Purpose — This ordinance is established to regulate the installation and operation of
Wind Energy Conversion Systems (WECS) within County not otherwise
subject to siting and oversight by the State of Minnesota under the Minnesota Power
Plant Siting Act (MS 116C.51 -116C.697. )
Interpretation, Conflict and Separability'
Interpretation — In interpreting these regulations and their application, the
provisions of these regulations shall be held to be the minimum requirements for
the protection of public health, safety and general welfare. These regulations
shall be constructed to broadly promote the purposes for which they are adopted.
Conflict - These regulations are not intended to interfere with, abrogate or annul
any other ordinance, rule or regulation, statute or other provision of law except as
provided in these regulations. No other provision of these regulations that impose
restrictions different from any other ordinance, rule or regulation, statute or
provision of law, the provision that is more restrictive or imposes higher standards
shall control.
Separability — If any part or provision of these regulations or the application of
these regulations to any developer or circumstances is ajudged invalid by any
competent jurisdiction, the judgment shall be confined in its operation to the part,
provision or application directly involved in the controversy in which the
judgment shall be rendered and shall not affect or impair the validity of the
remainder of these regulations or the application of them to other developers or
circumstances.
Enforcement, Violations, Remedies and Penalties
Enforcement of the Wind Energy Conversion System Ordinance shall be done in
accordance with process and procedures established in Section of the
County Zoning Ordinance.
` The County may wish to examine the Interpretation, Conflict and Separability language in its other
ordinances and utilize consistent language.
Definitions
WECS - Wind Energy Conversion System: An electrical generating facility comprised of
one or more wind turbines and accessory facilities, including but not limited to: power
lines, transformers, substations and metrological towers, that operate by converting the
kinetic energy of wind into electrical energy. The energy maybe used on -site or
distributed into the electrical grid.
Aggregated Project: Aggregated projects are those which are developed and operated in
a coordinated fashion, but which have multiple entities separately owning one or more of
the individual WECS within the larger project. Associated infrastructure such as power
lines and transformers that service the facility may be owned by a separate entity but are
also included in the aggregated project.
Commercial WECS: A WECS of equal to or greater than [100/40] kW in total name
plate generating capacity.2
Non -Commercial WECS: A WECS less than [ 100/40] kW in total name plate generating
Capacity.
Fall Zone: The area, defined as the furthest distance from the tower base, in which a
guyed tower will collapse in the event of a structural failure. This area is less than the
total height of the structure.
Feeder Line: Any power line that carries electrical power from one or more wind
turbines or individual transformers associated with an individual wind turbine to the point
of interconnection with the electric power grid, in the case of interconnection with the
high voltage transmission systems the point of interconnection shall be the substation
serving the WECS.
Meteorological Tower: For the purposes of this Wind Energy Conversation System
Ordinance, meteorological towers are those tower which are erected primarily to measure
wind speed and directions plus other data relevant to siting WECS. Meteorological
towers do not include towers and equipment used by airports, the Minnesota Department
of Transportation, or other similar applications to monitor weather conditions.
2 40 kw and 100 kw are both reasonable standards for defining the Commercial WECS threshold. In
Minnesota, renewable energy projects of less than 40 kW are covered by a "Net Metering" law. This
allows the electrical generating facility to effectively receive retail rate for all energy sold to the local
utility. 100 kW is a significantly larger, but is relatively speaking a small electric generator. Federal and
state laws also have established relatively favorable procedures and rates for interconnecting renewable
generators of under 100 kW capacity. Refurbished wind turbines are currently available in capacities
between 40 and 100 kW. Some counties may find that that these turbines are fully consistent with
surrounding land uses and opt for a less rigorous set of standards and conditions.
Micro-WECs: Micro-WECS are WECS of 1 kW nameplate generating capacity or less
and utilizing supporting towers of 40 feed or less.
Property line: The boundary line of the area over which the entity applying for WECS
permit has legal control for the purposes of installation of a WECS. This control may be
attained through fee title ownership, easement, or other appropriate contractual
relationship between the project developer and landowner.
Rotor diameter: The diameter of the circle described by the moving rotor blades.
Substations: Any electrical facility designed to convert electricity produced by wind
turbines to a voltage greater than (35,000 KV) for interconnection with high voltage
transmission lines shall be located outside of the road right of way.
Total height: The highest point, above ground level, reached by a rotor tip or any other
part of the WECS.
Transmission Line: Those electrical power lines that carry voltages of at least 69,000
volts (69 KV) and are primarily used to carry electric energy over medium to long
distances rather than directly interconnecting and supplying electric energy to retail
customers.
Tower: Towers include vertical structures that support the electrical generator, rotor
blades, or meteorological equipment.
Tower height: The total height of the WECS exclusive of the rotor blades.
Public conservation lands: Land owned in fee title by State or Federal agencies and
managed specifically for [grassland] conservation purposes, including but not limited to
State Wildlife Management Areas, State Parks, State Scientific and Natural Areas, federal
Wildlife Refuges and Waterfowl Production Areas. For the purposes of this section
public conservation lands will also include lands owned in fee title by non-profit
conservation organizations. Public conservation lands do not include private lands upon
which conservation easements have been sold to public resource management agencies or
non-profit conservation organizations.
Wind Turbine: A wind turbine is any piece of electrical generating equipment that
converts the kinetic energy of blowing wind into electrical energy through the use of
airfoils or similar devices to capture the wind.
Procedures:
[Zoning / Land Use] Permits, Conditional Use Permits and Variances shall be applied for
and reviewed under the procedures established in Section of the
County's Zoning Ordinance, except where noted below.
The application for all WECS shall include the following information:
• The names of project applicant
• The name of the project owner
• The legal description and address of the project.
• A description of the project including: Number, type, name plate generating
capacity, tower height, rotor diameter, and total height of all wind turbines and
means of interconnecting with the electrical grid.
• Site layout, including the location of property lines, wind turbines, electrical
wires, interconnection points with the electrical grid, and all related accessory
structures. The site layout shall include distances and be drawn to scale.
• Engineer's certification
• Documentation of land ownership or legal control of the property
The application for Commercial WECS shall also include:
• The latitude and longitude of individual wind turbines.
• A USGS topographical map, or map with similar data, of the property and
surrounding area, including any other WECS within 10 rotor diameters of the
Proposed WECS.
• Location of wetlands or natural areas within 1,320 feet of the proposed WECS.
• [An Acoustical analysis]
• FAA Permit Application
• Location of all known Communications Towers within 2 miles of the proposed
WECS.
• Decommissioning Plan
• Description of potential impacts on nearby WECS and wind resources on adjacent
properties.
Aggregated Projects — Procedures
Aggregated Projects may jointly submit a single application and be reviewed under joint
proceedings, including notices, hearings, reviews and as appropriate approvals. Permits
will be issued and recorded separately. Joint applications will be assessed fees as one
project. [Aggregated projects having a combined capacity equal to or greater than the
threshold for State oversight as set forth in MS Statute 116C.691 through 116C.697 shall
be regulated by the State of Minnesota.]3
3 Aggregated projects have been a grey area, with some regulated by the State and some regulated by
Counties. The County may wish to remove uncertainty by directing that all aggregated projects over the 5
MW threshold currently outlined in statute be subject to state regulation. During late 2004, however, the
Minnesota Environmental Quality Board determined that aggregated projects of 5 MW or more are the
jurisdiction of the State, as long as the projects are using one substation and being installed by one
developer.
District Regulations
WECS will be permitted, conditionally permitted or not permitted based on the
generating capacity and land use district as established in the table below:
District
Non-
Commercial*
Commercial
Meteorological
Tower*
Agriculture (A-1,
A-2, A-3)
Permitted
Conditionally Permitted
Permitted
Rural Residential
Conditionally
permitted
Not permitted
Not Permitted
Rural Town Site
Not permitted
Not permitted
Not Permitted
General Business
District
Not permitted
Not Permitted
Not permitted
Highway
Commercial
Conditionally
permitted
Not Permitted
Permitted
Light Industry
Permitted
Conditionally Permitted
Permitted
Heavy Industry
Permitted
Conditionally Permitted
Permitted
Shoreland
[may depend upon
the lake and the
specific district]
Not permitted
Not permitted
Urban Expansion
Overlay District
Conditionally
permitted
Not permitted
Not permitted
Conservation /
Special Protection
Shoreland
Wild and Scenic
River
[requires
examination of the
district purpose,
the underlying
resource and the
impacts of a wind
turbine on that
resource]
Conditionally
permitted
Conditionally
permitted
[requires examination of
the district purpose, the
underlying resource and
the impacts of a wind
turbine on that resource]
Not permitted
Not permitted
[Requires
examination of the
district purpose,
the underlying
resource and the
impacts of a wind
turbine on that
resource]
Not permitted
Not permitted
[* Non -Commercial WECS and Meteorological towers shall require a conditional
use permit if over feet in height in accordance with Section
of the County Zoning Ordinance.]
[The county may choose to establish a Wind Energy Development Overlay District in
lieu of permitting or not permitting wind in existing zoning districts. Counties may also
consider a third category of WECs, "Micro Turbines" which have a name plate capacity
equal to or less than 1 kW and utilizing towers of less than 40 feet. Permitting would be
more permissive for these machines. ]
Setbacks — Wind Turbines and Meteorological Towers
All towers shall adhere to the setbacks established in the following table.
Wind Turbine —
Non- Commercial WECS
Wind Turbine - Commercial
WECS
Meteorological
Towers4
Property lines
1.1 times the total height or
in Agricultural or Industrial
Land Use Districts only.
the distance of the fall
zone, as certified by a
professional engineer + 10
feet.
[ 1.1 / 1.25] times the total
height
The fall zone, as
certified by a
professional
engineer, + 10 feet
or 1.1 times the
total height.
[Neighboring]
Dwellings [*]
750 feet
The fall zone, as
certified by a
professional
engineer, + 10 feet
or 1.1 times the
total height.
Road Rights -of -Way [**]
The distance of the fall
zone as certified by a
professional engineer + 10
feet or 1 times the total
height. [Or equivalent to
centerline]
1 times the height,
may be reduced for minimum
maintenance roads or a road
with Average Daily Traffic
Count of less than 10.
[Or equivalent to centerline]
The fall zone, as
certified by a
professional
engineer, + 10 feet
or 1 times the total
height.
Other Rights -of -Way
(Railroads, power lines,
etc)
The lesser of 1 times the
total height or the distance
of the fall zone, as certified
by a professional engineer
+ 10 feet.
To be considered by the
planning commission
The fall zone, as
certified by a
professional
engineer, + 10 feet
or 1 times the total
height.
Public conservation lands
managed as grasslands
NA
600 feet
600 feet
Wetlands, USFW Types
III, IV and V
NA
600 feet
600 feet
Other Structures
To be considered
Other Existing WECS
NA
To be considered based on:
- Relative size of the existing
and proposed WECS
-Alignment of the WECS
relative to the predominant
winds.
The county may have an existing tower ordinance in place, and inay choose to regulate meteorological
towers under that ordinance.
-Topography
-Extent of wake interference
impacts on existing WECS.
-Property line setback of
existing WECS.
-Other setbacks required.
Waived for internal setbacks in
multiple turbine projects
including aggregated projects.
River Bluff'
[500 / 1,000 / 1,320 / ]
[* The setback for dwellings shall be reciprocal in that no dwelling shall be constructed
within 750 feet of a commercial wind turbine.]
[** The setback shall be measured from future rights -of -way if a planned changed or
expanded right-of-way is known.]
Setbacks — substations and accessory facilities
Minimum setback standards for substations and feeder lines shall be consistent
with the standards for essential services established in Section of the
County Zoning Ordinance.
[Substation setbacks
- 0 feet / structure setback from road ROW — located wholly outside the
ROW.
- property lines 0 feet / structure setback from property lines/side yard.]
Requirements and Standards
Safety Design Standards
The intent here is to minimize the impact on the scenic qualities of major rivers valleys such as the
Mississippi, St. Croix and Minnesota. Care should be taken to avoid excessive setbacks, particularly from
bluffs overlooking smaller tributaries to the major river. Wabasha County Minnesota has adopted 1/4 mile
setbacks from bluffs overlooking tributaries as well as the the Mississippi River. This effectively creates a
broad corridor where WECS are prohibited. It may be more appropriate in areas with complex terrain to
develop an overlay map that identifies specific areas where wind development is prohibited.
6 Nearly all zoning ordinances address "essential services" which usual includes electric power lines, and
related equipment such as substations. Most substations are sited adjacent to the road ROWs. This
conserves farm land and reduces costs for such facilities, but creates some concerns for road authorities
including site lines, snow drifting, and financial liabilities that might result from road re -construction. It is
recommended that substations associated with WECS be regulated in a manner consistent with essential
service regulations. However, if those regulations are clear then it may be appropriate to establish specific
setbacks in the WECS ordinance.
Engineering Certification — For all WECS, the manufacture's engineer or another
qualified engineer shall certify that the turbine, foundation and tower design of
the WECS is within accepted professional standards, given local soil and climate
conditions.
Clearance — Rotor blades or airfoils must maintain at least 12 feet of clearance
between their lowest point and the ground.
Warnings —
For all Commercial WECS, a sign or signs shall be posted on the tower,
transformer and substation warning of high voltage. [Signs with
emergency contact information shall also be posted on the turbine or at
another suitable point.]
For all guyed towers, visible and reflective objects, such as plastic sleeves,
reflectors or tape, shall be placed on the guy wire anchor points and along
the outer and innermost guy wires up to a height of 8 feet above the
ground. [Visible fencing shall be installed around anchor points of guy
wires.]
[Consideration shall be given to painted aviation warning on metrological
towers of less than 200 feet.]
Standards
Total height — Non -Commercial WECS shall have a total height of less than 200
feet.
[Section of this ordinance requires a conditional use for all structures over
feet in total height. In those districts where meteorological towers are a
permitted use, meteorological towers of less than 200 feet shall be exempt from
Conditional Use process established for structures of over feet in height.]'
Tower configuration —
All wind turbines, which are part of a commercial WECS, shall be
installed with a tubular, monopole type tower.
In adopting this ordinance, care should be taken to ensure that this section and the District Regulations
section are consistent. Most county zoning ordinances require a Conditional Use Permit for structures of
100' or greater. If a county chooses to exempt meteorological towers from the CUP process, it should
include that language here, and not include the reference back to that section in the District regulations.
Conversely, if the county does not wish to exempt meteorological towers from the height triggers for CUP,
this language should not be adopted
Meteorological towers may be guyed.
Color and Finish — All wind turbines and towers that are part of a commercial
WECS shall be white, grey and another non -obtrusive color. Blades may be black
in order to facilitate deicing. Finishes shall be matt or non -reflective.
[Exceptions may be made for metrological towers, where concerns exist relative
to aerial spray applicators.]
Lighting — Lighting including lighting intensity and frequency of strobe, shall
adhere to but not exceed requirements established by Federal Aviation
Administration permits and regulations. Red strobe lights are preferred for night-
time illumination to reduce impacts on migrating birds. Red pulsating
incandescent lights should be avoided. [Exceptions may be made for metrological
towers, where concerns exist relative to aerial spray applicators.]
Other Signage — All signage on site shall comply with section [sign ordinance] of
the County Ordinance. The manufacturer's or owner's company
name and /or logo may be placed upon the nacelle, compartment containing the
electrical generator, of the WECS.
Feeder Lines — All communications and feeder lines, equal to or less than 34.5 kV
in capacity, installed as part of a WECS shall be buried [where reasonably
feasible]. Feeder lines installed as part of a WECS shall not be considered an
essential service. This standard applies to all feeder lines subject to
County authority. 8
Waste Disposal — Solid and Hazardous wastes, including but not limited to crates,
packaging materials, damaged or worn parts, as well as used oils and lubricants,
shall be removed from the site promptly and disposed of in accordance with all
applicable local, state and federal regulations.
Discontinuation and Decommissioning - A WECS shall be considered a
discontinued use after 1 year without energy production, unless a plan is
developed and submitted to the County Zoning Administrator outlining
the steps and schedule for returning the WECS to service. All WECS and
accessory facilities shall be removed to [ground level / four feet below ground
level] within 80 days of the discontinuation use.
9
$ The model ordinance references the Essential Services Ordinance for determining setbacks for substations
and feeder lines in the Setback Section. However, the intent is not to necessarily define the feeder lines as
an essential service. The model ordinance anticipates that there will be projects that run feeder lines to
interconnection points that are off site. The ordinance does not intend to provide commercial projects with
the same prerogatives as a essential services, but rather to simplify determination of setbacks and
placement of substations and feeder lines relative to rights -of -ways.
9 Removal of materials will provide differing protections to the public welfare. Removal to ground level
will eliminate the potential for blight and safety concerns associated with un-maintained equipment left
Each Commercial WECS shall have a Decommissioning plan outlining the
anticipated means and cost of removing WECS at the end of their serviceable life
or upon becoming a discontinued use. The cost estimates shall be made by a
competent party; such as a Professional Engineer, a contractor capable of
decommissioning or a person with suitable expertise or experience with
decommissioning. The plan shall also identify the financial resources that will be
available to pay for the decommissioning and removal of the WECS and
accessory facilities.
Orderly Development — Upon issuance of a conditional use permit, all
Commercial WECs shall notify the Environmental Quality Board Power Plant
Siting Act program Staff of the project location and details on the survey form
specified by the Environmental Quality Board.
Other Applicable Standards
Noise — All WECS shall comply with Minnesota Rules 7030 governing
noise.
Electrical codes and standards — All WECS and accessory equipment and
facilities shall comply with the National Electrical Code and other
applicable standards.
Federal Aviation Administration— All WECS shall comply with FAA
standards.
[Uniform Building Code — All WECS shall comply with the Uniform
Building Code adopted by the State of Minnesota.]
Interference — The applicant shall minimize or mitigate any interference with
electromagnetic communications, such as radio, telephone, microwaves, or
television signals cause by any WECS. The applicant shall notify all
communication tower operators within [two / five] miles of the proposed WECS
location upon application to the county for permits. No WECs shall be
constructed so as to interfere with County or Minnesota Department of
Transportation microwave transmissions.
Avoidance and Mitigation of Damages to Public Infrastructure —
Roads — Applicants shall:
Identify all county, city or township roads to be used for the purpose of
transporting WECS, substation parts, cement, and/or equipment for
standing. Deeper removal will facilitate the return of the site to agricultural production or other uses. The
shallow removal will allow resumption of cropping, and the deeper removal will allow for future tiling or
drainage projects.
construction, operation or maintenance of the WECS and or Substation
and obtain applicable weight and size permits from impacted road
authority(ies) prior to construction.
[Conduct a pre -construction survey, in coordination with the impacted
local road authority(ies) to determine existing road conditions. The survey
shall include photographs and a written agreement to document the
condition of the public facility.
Be responsible for restoring or paying damages as agreed to buy the
applicable road authority(ies) sufficient to restore the road(s) to
preconstruction conditions.]
Drainage System — The Applicant shall be responsible for immediate repair of
damage to public drainage systems stemming from construction, operation or
maintenance of the WECS.
Attachment 3 - Study from MN Dept of Health
Public Health Impacts
of
Wind Turbines
Prepared by:
Minnesota Department of Health
Environmental Health Division
In response to a request from:
Minnesota Department of Commerce
Office of Energy Security
May 22, 2009
Table of Contents
Table of Contents ii
Tables
Figures iii
L Introduction 1
A. Site Proposals 1
1. Bent Tree Wind Project in Freeborn County 3
2. Noble Flat Hill Wind Park in Clay, Becker and Ottertail Counties 3
B. Health Issues 6
II. Elementary Characteristics of Sensory Systems and Sound 6
A. Sensory Systems 6
1. Hearing 6
2. Vestibular System 7
B. Sound 8
1. Introduction 8
Audible Frequency Sound 8
Sub -Audible Frequency Sound 9
Resonance and modulation 9
2. Human Response to Low Frequency Stimulation 10
3. Sound Measurements 10
III. Exposures of Interest 11
A. Noise From Wind Turbines 11
1. Mechanical noise 11
2. Aerodynamic noise 11
3. Modulation of aerodynamic noise 12
4. Wind farm noise 14
B. Shadow Flicker 14
IV. Impacts of Wind Turbine Noise 15
A. Potential Adverse Reaction to Sound 15
Annoyance, unpleasant sounds, and complaints 15
B. Studies of Wind Turbine Noise Impacts on People 17
1. Swedish Studies 17
2. United Kingdom Study 17
3. Netherlands Study 17
4. Case Reports 18
V. Noise Assessment and Regulation 19
1. Minnesota noise regulation 19
2. Low frequency noise assessment and regulation 19
3. Wind turbine sound measurements 22
4. Wind turbine regulatory noise limits 24
VI. Conclusions 25
VII. Recommendations 26
VIII. Preparers of the Report: 26
IX. References 27
ii
Tables
Table 1: Minnesota Class 1 Land Use Noise Limits 19
Table 2: 35 dB(A) (nominal, 8 Hz-20KHz) Indoor Noise from Various Outdoor Environmental
Sources 22
Figures
Figure 1: Wind turbines 2
Figure 2: Bent Tree Wind Project, Freeborn County 4
Figure 3: Noble Flat Hill Wind Park, Clay, Becker, Ottertail Counties 5
Figure 4: Audible Range of Human Hearing 9
Figure 5: Sources of noise modulation or pulsing 13
Figure 6: Annoyance associated with exposure to different environmental noises 20
Figure 7: 1/3 Octave Sound Pressure Level Low frequency Noise Evaluation Curves 21
Figure 8: Low Frequency Noise from Wind Farm: Parked, Low Wind Speed, and High Wind
Speed 23
Figure 9: Change in Noise Spectrum as Distance from Wind Farm Changes 24
iii
I. Introduction
In late February 2009 the Minnesota Department of Health (MDH) received a request
from the Office of Energy Security (OES) in the Minnesota Department of Commerce,
for a "white paper" evaluating possible health effects associated with low frequency
vibrations and sound arising from large wind energy conversion systems (LWECS). The
OES noted that there was a request for a Contested Case Hearing before the Minnesota
Public Utilities Commission (PUC) on the proposed Bent Tree Wind Project in Freeborn
County Minnesota; further, the OES had received a long comment letter from a citizen
regarding a second project proposal, the Lakeswind Wind Power Plant in Clay, Becker
and Ottertail Counties, Minnesota. This same commenter also wrote to the Commissioner
of MDH to ask for an evaluation of health issues related to exposure to low frequency
sound energy generated by wind turbines. The OES informed MDH that a white paper
would have more general application and usefulness in guiding decision -making for
future wind projects than a Contested Case Hearing on a particular project. (Note: A
Contested Case Hearing is an evidentiary hearing before an Administrative Law Judge,
and may be ordered by regulatory authorities, in this case the PUC, in order to make a
determination on disputed issues of material fact. The OES advises the PUC on need and
permitting issues related to large energy facilities.)
In early March 2009, MDH agreed to evaluate health impacts from wind turbine noise
and low frequency vibrations. In discussion with OES, MDH also proposed to examine
experiences and policies of other states and countries. MDH staff appeared at a hearing
before the PUC on March 19, 2009, and explained the purpose and use of the health
evaluation. The Commissioner replied to the citizen letter, affirming that MDH would
perform the requested review.
A brief description of the two proposed wind power projects, and a brief discussion of
health issues to be addressed in this report appear below.
A. Site Proposals
Wind turbines are huge and expensive machines requiring large capitol investment.
Figure 1 shows some existing wind turbines in Minnesota. Large projects require control
of extensive land area in order to optimize spacing of turbines to minimize turbulence at
downwind turbines. Towers range up to 80 to 100 meters (260 to 325 feet), and blades
can be up to 50 meters long (160 feet) (see Tetra Tech, 2008; WPL, 2008). Turbines are
expected to be in place for 25-30 years.
1
1. Bent Tree Wind Project in Freeborn County
This is a proposal by the Wisconsin Power and Light Company (WPL) for a 400
megawatt (MW) project in two phases of 200 MW each (requiring between 80 and 130
wind turbines). The cost of the first phase is estimated at $497 million. The project site
area would occupy approximately 40 square miles located 4 miles north and west of the
city of Albert Lea, approximately 95 miles south of Minneapolis (Figure 2) (WPL, 2008).
The Project is a LWECS and a Certificate of Need (CON) from the PUC is required
(Minnesota Statutes 216B.243). The PUC uses the CON process to determine the basic
type of facility (if any) to be constructed, the size of the facility, and when the project
will be in service. The CON process involves a public hearing and preparation of an
Environmental Report by the OES. The CON process generally takes a year, and is
required before a facility can be permitted.
WPL is required to develop a site layout that optimizes wind resources. Accordingly,
project developers are required to control areas at least 5 rotor diameters in the prevailing
(north -south) wind directions (between about 1300 and 1700 feet for the 1.5 to 2.5 MW
turbines under consideration for the project) and 3 rotor diameters in the crosswind (east -
west) directions (between about 800 and 1000 feet). Thus, these are minimum setback
distances from properties in the area for which easements have not been obtained.
Further, noise rules promulgated by the Minnesota Pollution Control Agency (MPCA;
Minnesota Rules Section 7030), specify a maximum nighttime noise in residential areas
of 50 A -weighted decibels (dB(A). WPL has proposed a minimum setback of 1,000 feet
from occupied structures in order to comply with the noise rule.
2. Noble Flat Hill Wind Park in Clay, Becker and Ottertail Counties
This is a LWECS proposed by Noble Flat Hill Windpark I (Noble), a subsidiary of Noble
Environmental Power, based in Connecticut. The proposal is for a 201 MW project
located 12 miles east of the City of Moorhead, about 230 miles northwest of Minneapolis
(Figure 3) (Tetra Tech, 2008). The cost of the project is estimated to be between $382
million and $442 million. One hundred thirty-four GE 1.5 MW wind turbines are planned
for an area of 11,000 acres (about 17 square miles); the site boundary encompasses
approximately 20,000 acres. Setback distances of a minimum of 700 feet are planned to
comply with the 50 dB(A) noise limit. However, rotor diameters will be 77 meters (250
feet). Therefore, setback distances in the prevailing wind direction of 1,300 feet are
planned for properties where owners have not granted easements. Setbacks of 800 feet
are planned in the crosswind direction.
3
Figure 2: Bent Tree Wind Project, Freeborn County
A.
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MINNESOTA
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Figure 3: Noble Flat Hill Wind Park, Clay, Becker, Ottertail Counties
5
B. Health Issues
The National Research Council of the National Academies (NRC, 2007) has reviewed
impacts of wind energy projects on human health and well-being. The NRC begins by
observing that wind projects, just as other projects, create benefits and burdens, and that
concern about impacts is natural when the source is near one's home. Further, the NRC
notes that different people have different values and levels of sensitivity. Impacts noted
by the NRC that may have the most effect on health include noise and low frequency
vibration, and shadow flicker. While noise and vibration are the main focus of this paper,
shadow flicker (casting of moving shadows on the ground as wind turbine blades rotate)
will also be briefly discussed.
Noise originates from mechanical equipment inside the nacelles of the turbines (gears,
generators, etc.) and from interaction of turbine blades with wind. Newer wind turbines
generate minimal noise from mechanical equipment. The most problematic wind turbine
noise is a broadband "whooshing" sound produced by interaction of turbine blades with
the wind. Newer turbines have upwind rotor blades, minimizing low frequency
"infrasound" (i.e., air pressure changes at frequencies below 20-100 Hz that are
inaudible). However, the NRC notes that during quiet conditions at night, low frequency
modulation of higher frequency sounds, such as are produced by turbine blades, is
possible. The NRC also notes that effects of low frequency (infrasound) vibration (less
than 20 Hz) on humans are not well understood, but have been asserted to disturb some
people.
Finally, the NRC concludes that noise produced by wind turbines is generally not a major
concern beyond a half mile. Issues raised by the NRC report and factors that may affect
distances within which wind turbine noise may be problematic are discussed more
extensively below.
II. Elementary Characteristics of Sensory Systems and Sound
A. Sensory Systems
1. Hearing
Sensory systems respond to a huge dynamic range of physical stimuli within a relatively
narrow dynamic range of mechanical, chemical and/or neuronal (electrophysiological)
output. Compression of the dynamic range is accomplished by systems that respond to
logarithmic increases in intensity of physical stimuli with arithmetically increasing
sensory responses. This :eneral property is true for hearing, and has been recognized
since at least the mid -19` century (see e.g., Woodworth and Schlosberg, 1964).
"Loudness" is the sensory/perceptual correlate of the physical intensity of air pressure
changes to which the electro-mechanical transducers in the ear and associated neuronal
pathways are sensitive. Loudness increases as the logarithm of air pressure, and it is
convenient to relate loudness to a reference air pressure (in dyne/cm' or pascals) in tenths
of logarithmic units (decibels; dB). Further, the ear is sensitive to only a relatively narrow
frequency range of air pressure changes: those between approximately 20 and 20,000
cycles per second or Herz (Hz). In fact, sensitivity varies within this range, so that the
sound pressure level relative to a reference value that is audible in the middle of the range
6
(near 1,000 Hz) is about 4 orders of magnitude smaller than it is at 20 Hz and about 2
orders of magnitude smaller than at 20,000 Hz (Fig. 3). Accordingly, measurements of
loudness in dB generally employ filters to equalize the loudness of sounds at different
frequencies or "pitch." To approximate the sensitivity of the ear, A -weighted filters
weigh sound pressure changes at frequencies in the mid -range more than those at higher
or lower frequencies. When an A -weighted filter is used, loudness is measured in dB(A).
This is explained in greater detail in Section B below.
The ear accomplishes transduction of sound through a series of complex mechanisms
(Guyton, 1991). Briefly, sound waves move the eardrum (tympanic membrane), which is
in turn connected to 2 small bones (ossicles) in the middle ear (the malleus and incus). A
muscle connected to the malleus keeps the tympanic membrane tensed, allowing efficient
transmission to the malleus of vibrations on the membrane. Ossicle muscles can also
relax tension and attenuate transmission. Relaxation of muscle tension on the tympanic
membrane protects the ear from very loud sounds and also masks low frequency sounds,
or much background noise. The malleus and incus move a third bone (stapes). The stapes
in turn applies pressure to the fluid of the cochlea, a snail -shaped structure imbedded in
temporal bone. The cochlea is a complex structure, but for present purposes it is
sufficient to note that pressure changes or waves of different frequencies in cochlear fluid
result in bending of specialized hair cells in regions of the cochlea most sensitive to
different frequencies or pitch. Hair cells are directly connected to nerve fibers in the
vestibulocochlear nerve (VIII cranial nerve).
Transmission of sound can also occur directly through bone to the cochlea. This is a very
inefficient means of sound transmission, unless a device (e.g. a tuning fork or hearing
aid) is directly applied to bone (Guyton, 1991).
2. Vestibular System
The vestibular system reacts to changes in head and body orientation in space, and is
necessary for maintenance of equilibrium and postural reflexes, for performance of rapid
and intricate body movements, and for stabilizing visual images (via the vestibulo-ocular
reflex) as the direction of movement changes (Guyton, 1991).
The vestibular apparatus, like the cochlea, is imbedded in temporal bone, and also like
the cochlea, hair cells, bathed in vestibular gels, react to pressure changes and transmit
signals to nerve fibers in the vestibulocochlear nerve. Two organs, the utricle and saccule,
called otolith organs, integrate information about the orientation of the head with respect
to gravity. Otoliths are tiny stone -like crystals, embedded in the gels of the utricle and
saccule, that float as the head changes position within the gravitational field. This
movement is translated to hair cells. Three semi -circular canals, oriented at right angles
to each other, detect head rotation. Stimulation of the vestibular apparatus is not directly
detected, but results in activation of motor reflexes as noted above (Guyton, 1991).
Like the cochlea, the vestibular apparatus reacts to pressure changes at a range of
frequencies; optimal frequencies are lower than for hearing. These pressure changes can
be caused by body movements, or by direct bone conduction (as for hearing, above) when
vibration is applied directly to the temporal bone (Todd et al., 2008). These investigators
7
found maximal sensitivity at 100 Hz, with some sensitivity down to 12.5 Hz. The saccule,
located in temporal bone just under the footplate of the stapes, is the most sound -sensitive
of the vestibular organs (Halmagyi et al., 2004). It is known that brief loud clicks (90-95
dB) are detected by the vestibular system, even in deaf people. However, we do not know
what the sensitivity of this system is through the entire range of sound stimuli.
While vestibular system activation is not directly felt, activation may give rise to a
variety of sensations: vertigo, as the eye muscles make compensatory adjustments to
rapid angular motion, and a variety of unpleasant sensations related to internal organs. In
fact, the vestibular system interacts extensively with the "autonomic" nervous system,
which regulates internal body organs (Balaban and Yates, 2004). Sensations and effects
correlated with intense vestibular activation include nausea and vomiting and cardiac
arrhythmia, blood pressure changes and breathing changes.
While these effects are induced by relatively intense stimulation, it is also true that A -
weighted sound measurements attuned to auditory sensitivity, will underweight low
frequencies for which the vestibular system is much more sensitive (Todd et al., 2008).
Nevertheless, activation of the vestibular system per se obviously need not give rise to
unpleasant sensations. It is not known what stimulus intensities are generally required for
for autonomic activation at relatively low frequencies, and it is likely that there is
considerable human variability and capacity to adapt to vestibular challenges.
B. Sound
1. Introduction
Sound is carried through air in compression waves of measurable frequency and
amplitude. Sound can be tonal, predominating at a few frequencies, or it can contain a
random mix of a broad range of frequencies and lack any tonal quality (white noise).
Sound that is unwanted is called noise.
Audible Frequency Sound
Besides frequency sensitivity (between 20 and 20,000 Hz), humans are also sensitive to
changes in the amplitude of the signal (compression waves) within this audible range of
frequencies. Increasing amplitude, or increasing sound pressure, is perceived as
increasing volume or loudness. The sound pressure level in air (SPL) is measured in
micro Pascals (µPa). SPLs are typically converted in measuring instruments and reported
as decibels (dB) which is a log scale, relative unit (see above). When used as the unit for
sound, dBs are reported relative to a SPL of 20 µPa. Twenty µPa is used because it is the
approximate threshold of human hearing sensitivity at about 1000 Hz. Decibels relative
to 20 µPa are calculated from the following equation:
Loudness (dB) = Log ((SPL / 20 µPa)`) * 10
Figure 4 shows the audible range of normal human hearing. Note that while the threshold
sensitivity varies over the frequency range, at high SPLs sensitivity is relatively
consistent over audible frequencies.
8
Figure 4: Audible Range of Human Hearing
120 —
Sound Pressure Level
(a
100 —
o.
80
N
60
.r
= 40
20
m
0
-20
105 dB(C)
isopleth
—20 dB(A)
isopleth
•
10 100 1000 10000 100000
Frequency (Hz)
Equivalence curves for different frequencies, when sound meter readings in dB
are taken with A or C -weighting filters. (Adapted from EPD Hong Kong SAR,
2009)
Sub -Audible Frequency Sound
Sub -audible frequency sound is often called infrasound. It may be sensed by people,
similar to audible sound, in the cochlear apparatus in the ear; it may be sensed by the
vestibular system which is responsible for balance and physical equilibrium; or it may be
sensed as vibration.
Resonance and modulation
Sound can be attenuated as it passes through a physical structure. However, because the
wavelength of low frequency sound is very long (the wavelength of 40 Hz in air at sea
level and room temperature is 8.6 meters or 28 ft), low frequencies are not effectively
attenuated by walls and windows of most homes or vehicles. (For example, one can
typically hear the bass, low frequency music from a neighboring car at a stoplight, but not
the higher frequencies.) In fact, it is possible that there are rooms within buildings
exposed to low frequency sound or noise where some frequencies may be amplified by
resonance (e.g. 1/2 wavelength, 1/4 wavelength) within the structure. In addition, low
frequency sound can cause vibrations within a building at higher, more audible
frequencies as well as throbbing or rumbling.
Sounds that we hear generally are a mixture of different frequencies. In most instances
these frequencies are added together. However, if the source of the sound is not constant,
but changes over time, the effect can be re -occurring pulses of sound or low frequency
modulation of sound. This is the type of sound that occurs from a steam engine, a jack
hammer, music and motor vehicle traffic. Rhythmic, low frequency pulsing of higher
frequency noise (like the sound of an amplified heart beat) is one type of sound that can
be caused by wind turbine blades under some conditions.
9
2. Human Response to Low Frequency Stimulation
There is no consensus whether sensitivity below 20 Hz is by a similar or different
mechanism than sensitivity and hearing above 20 Hz (Reviewed by Moller and Pedersen,
2004). Possible mechanisms of sensation caused by low frequencies include bone
conduction at the applied frequencies, as well as amplification of the base frequency
and/or harmonics by the auditory apparatus (eardrum and ossicles) in the ear. Sensory
thresholds are relatively continuous, suggesting (but not proving) a similar mechanism
above and below 20 Hz. However, it is clear that cochlear sensitivity to infrasound (< 20
Hz) is considerably less than cochlear sensitivity to audible frequencies.
Moller and Pedersen (2004) reviewed human sensitivity at low and infrasonic
frequencies. The following findings are of interest:
• When whole -body pressure -field sensitivity is compared with ear -only
(earphone) sensitivity, the results are very similar. These data suggest that the
threshold sensitivity for low frequency is through the ear and not vestibular.
• Some individuals have extraordinary sensitivity at low frequencies, up to 25 dB
more sensitive than the presumed thresholds at some low frequencies.
• While population average sensitivity over the low frequency range is smooth,
sound pressure thresholds of response for individuals do not vary smoothly but
are inconsistent, with peaks and valleys or "microstructures". Therefore the
sensitivity response of individuals to different low frequency stimulation may
be difficult to predict.
• Studies of equal -loudness -levels demonstrate that as stimulus frequency
decreases through the low frequencies, equal -loudness lines compress in the dB
scale. (See Figure 4 as an example of the relatively small difference in auditory
SPL range between soft and loud sound at low frequencies).
• The hearing threshold for pure tones is different than the hearing threshold for
white noise at the same total sound pressure.
3. Sound Measurements
Sound measurements are taken by instruments that record sound pressure or the pressure
of the compression wave in the air. Because the loudness of a sound to people is usually
the primary interest in measuring sound, normalization schemes or filters have been
applied to absolute measurements. dB(A) scaling of sound pressure measurements was
intended to normalize readings to equal loudness over the audible range of frequencies at
low loudness. For example, a 5,000 Hz (5 kHz) and 20 dB(A) tone is expected to have
the same intensity or loudness as a 100 Hz, 20 dB(A) tone. However, note that the
absolute sound pressures would be about 200 µPa and 2000 µPa, respectively, or
about a difference of 20 dB (relative to 20 µPa), or as it is sometimes written 20
dB(linear).
Most sound is not a single tone, but is a mixture of frequencies within the audible range.
A sound meter can add the total SPLs for all frequencies; in other words, the dB readings
over the entire spectrum of audible sound can be added to give a single loudness metric.
If sound is reported as A -weighted, or dB(A), it is a summation of the dB(A) scaled
sound pressure from 20 Hz to 20 kHz.
10
In conjunction with the dB(A) scale, the dB(B) scale was developed to approximate equal
loudness to people across audible frequencies at medium loudness, and dB(C) was
developed to approximate equal -loudness for loud environments. Figure 4 shows
isopleths for 20 dB(A) and 105 dB(C). While dB(A), dB(B), dB(C) were developed from
empirical data at the middle frequencies, at the ends of the curves these scales were
extrapolated, or sketched in, and are not based on experimental or observational data
(Berglund et al., 1996). As a result, data in the low frequency range (and probably the
highest audible frequencies as well) cannot be reliably interpreted using these scales. The
World Health Organization (WHO, 1999) suggests that A -weighting noise that has a
large low frequency component is not reliable assessment of loudness.
The source of the noise, or the noise signature, may be important in developing equal -
loudness schemes at low frequencies. C -weighting has been recommended for artillery
noise, but a linear, unweighted scale may be even better at predicting a reaction
(Berglund et al., 1996). A linear or equal energy rating also appears to be the most
effective predictor of reaction to low frequency noise in other situations, including blast
noise from mining. The implication of the analysis presented by Berglund et al. (1996) is
that annoyance from non -tonal noise should not be estimated from a dB(A) scale, but
may be better evaluated using dB(C), or a linear non -transformed scale.
However, as will be discussed below, a number of schemes use a modified dB(A) scale to
evaluate low frequency noise. These schemes differ from a typical use of the dB(A) scale
by addressing a limited frequency range below 250 Hz, where auditory sensitivity is
rapidly changing as a function of frequency (see Figure 4).
III. Exposures of Interest
A. Noise From Wind Turbines
1. Mechanical noise
Mechanical noise from a wind turbine is sound that originates in the generator, gearbox,
yaw motors (that intermittently turn the nacelle and blades to face the wind), tower
ventilation system and transformer. Generally, these sounds are controlled in newer wind
turbines so that they are a fraction of the aerodynamic noise. Mechanical noise from the
turbine or gearbox should only be heard above aerodynamic noise when they are not
functioning properly.
2. Aerodynamic noise
Aerodynamic noise is caused by wind passing over the blade of the wind turbine. The tip
of a 40-50 meter blade travels at speeds of over 140 miles per hour under normal
operating conditions. As the wind passes over the moving blade, the blade interrupts the
laminar flow of air, causing turbulence and noise. Current blade designs minimize the
amount of turbulence and noise caused by wind, but it is not possible to eliminate
turbulence or noise.
Aerodynamic noise from a wind turbine may be underestimated during planning. One
source of error is that most meteorological wind speed measurements noted in wind farm
literature are taken at 10 meters above the ground. Wind speed above this elevation, in
11
the area of the wind turbine rotor, is then calculated using established modeling
relationships. In one study (van den Berg, 2004) it was determined that the wind speeds
at the hub at night were up to 2.6 times higher than modeled. Subsequently, it was found
that noise levels were 15 dB higher than anticipated.
Unexpectedly high aerodynamic noise can also be caused by improper blade angle or
improper alignment of the rotor to the wind. These are correctable and are usually
adjusted during the turbine break-in period.
3. Modulation of aerodynamic noise
Rhythmic modulation of noise, especially low frequency noise, has been found to be
more annoying than steady noise (Bradley, 1994; Holmberg et al., 1997). One form of
rhythmic modulation of aerodynamic noise that can be noticeable very near to a wind
turbine is a distance -to -blade effect. To a receptor on the ground in front of the wind
turbine, the detected blade noise is loudest as the blade passes, and quietest when the
blade is at the top of its rotation. For a modern 3 -blade turbine, this distance -to -blade
effect can cause a pulsing of the blade noise at about once per second (1 Hz). On the
ground, about 500 feet directly downwind from the turbine, the distance -to -blade can
cause a difference in sound pressure of about 2 dB between the tip of the blade at its
farthest point and the tip of the blade at its nearest point (48 meter blades, 70 meter
tower). Figure 5 demonstrates why the loudness of blade noise (aerodynamic noise)
pulses as the distance -to -blade varies for individuals close to a turbine.
If the receptor is 500 feet from the turbine base, in line with the blade rotation or up to
60° off line, the difference in sound pressure from the tip of the blade at its farthest and
nearest point can be about 4-5 dB, an audible difference. The tip travels faster than the
rest of the blade and is closer to (and then farther away from) the receptor than other parts
of the blade. As a result, noise from other parts of the blade will be modulated less than
noise from the tip. Further, blade design can also affect the noise signature of a blade.
The distance -to -blade effect diminishes as receptor distance increases because the relative
difference in distance from the receptor to the top or to the bottom of the blade becomes
smaller. Thus, moving away from the tower, distance -to -blade noise gradually appears to
be more steady.
Another source of rhythmic modulation may occur if the wind through the rotor is not
uniform. Blade angle, or pitch, is adjusted for different wind speeds to maximize power
and to minimize noise. A blade angle that is not properly tuned to the wind speed (or
wind direction) will make more noise than a properly tuned blade. Horizontal layers with
different wind speeds or directions can form in the atmosphere. This wind condition is
called shear. If the winds at the top and bottom of the blade rotation are different, blade
noise will vary between the top and bottom of blade rotation, causing modulation of
aerodynamic noise. This noise, associated with the blades passing through areas of
different air -wind speeds, has been called aerodynamic modulation and is demonstrated
in Figure 5.
12
Figure 5: Sources of noise modulation or pulsing
furthest (quietest)
Dista
osest (loudest)
20 mph
wind
source of aerodynamic
modulation noise
10 mph
wind
In some terrains and under some atmospheric conditions wind aloft, near the top of the
wind turbine, can be moving faster than wind near the ground. Wind turbulence or even
wakes from adjacent turbines can create non -uniform wind conditions as well. As a result
of aerodynamic modulation a rhythmic noise pattern or pulsing will occur as each blade
passes through areas with different wind speed. Furthermore, additional noise, or
thumping, may occur as each blade passes through the transition between different wind
speed (or wind direction) areas.
Wind shear caused by terrain or structures on the ground (e.g. trees, buildings) can be
modeled relatively easily. Wind shear in areas of flat terrain is not as easily understood.
During the daytime wind in the lower atmosphere is strongly affected by thermal
convection which causes mixing of layers. Distinct layers do not easily form. However,
in the nighttime the atmosphere can stabilize (vertically), and layers form. A paper by
G.P. van den Berg (2008) included data from a study on wind shear at Cabauw, The
Netherlands (flat terrain). Annual average wind speeds at different elevations above
ground was reported. The annual average wind speed at noon was about 5.75 meters per
second (m/s; approximately 12.9 miles per hour(mph)) at 20 m above ground, and about
7.6 m/s (17 mph) at 140 m. At midnight, the annual averages were about 4.3 m/s (9.6
mph) and 8.8 m/s (19.7 mph) for 20m and 140 m, respectively, above ground. The data
show that while the average windspeed (between 20m and 140m) is very similar at noon
and midnight at Cabauw, the windspeed difference between elevations during the day is
13
much less than the difference at night (1.85 m/s (4.1 mph) and 4.5 m/s (10 mph),
respectively). As a result one would expect that the blade angle can be better tuned to the
wind speed during the daytime. Consequently, blade noise would be greater at night.
A number of reports have included discussion of aerodynamic modulation (van den Berg,
2005; UK Department of Transport and Industry, 2006; UK Department for Business
Enterprise and Regulatory Reform, 2007; van den Berg, 2008). They suggest that
aerodynamic modulation is typically underestimated when noise estimates are calculated.
In addition, they suggest that detailed modeling of wind, terrain, land use and structures
may be used to predict whether modulation of aerodynamic noise will be a problem at a
proposed wind turbine site.
4. Wind farm noise
The noise from multiple turbines similarly distant from a residence can be noticeably
louder than a lone turbine simply through the addition of multiple noise sources. Under
steady wind conditions noise from a wind turbine farm may be greater than noise from
the nearest turbine due to synchrony between noise from more than one turbine (van den
Berg, 2005). Furthermore, if the dominant frequencies (including aerodynamic
modulation) of different turbines vary by small amounts, an audible beat or dissonance
may be heard when wind conditions are stable.
B. Shadow Flicker
Rhythmic light flicker from the blades of a wind turbine casting intermittent shadows has
been reported to be annoying in many locations (NRC, 2007; Large Wind Turbine
Citizens Committee, 2008). (Note: Flashing light at frequencies around 1 Hz is too slow
to trigger an epileptic response.)
Modeling conducted by the Minnesota Department of Health suggests that a receptor 300
meters perpendicular to, and in the shadow of the blades of a wind turbine, can be in the
flicker shadow of the rotating blade for almost 1'/z hour a day. At this distance a blade
may completely obscure the sun each time it passes between the receptor and the sun.
With current wind turbine designs, flicker should not be an issue at distances over 10
rotational diameters (-1000 meters or 1 km (0.6 mi) for most current wind turbines). This
distance has been recommended by the Wind Energy Handbook (Burton et al., 2001) as a
minimum setback distance in directions that flicker may occur, and has been noted in the
Bent Tree Permit Application (WPL, 2008).
Shadow flicker is a potential issue in the mornings and evenings, when turbine noise may
be masked by ambient sounds. While low frequency noise is typically an issue indoors,
shadow flicker can be an issue both indoors and outdoors when the sun is low in the sky.
Therefore, shadow flicker may be an issue in locations other than the home.
Ireland recommends wind turbines setbacks of at least 300 meters from a road to decrease
driver distraction (Michigan State University, 2004). The NRC (2007) recommends that
shadow flicker is addressed during the preliminary planning stages of a wind turbine
project.
14
IV. Impacts of Wind Turbine Noise
A. Potential Adverse Reaction to Sound
Human sensitivity to sound, especially to low frequency sound, is variable. Individuals
have different ranges of frequency sensitivity to audible sound; different thresholds for
each frequency of audible sound; different vestibular sensitivities and reactions to
vestibular activation; and different sensitivity to vibration.
Further, sounds, such as repetitive but low intensity noise, can evoke different responses
from individuals. People will exhibit variable levels of annoyance and tolerance for
different frequencies. Some people can dismiss and ignore the signal, while for others,
the signal will grow and become more apparent and unpleasant over time (Moreira and
Bryan, 1972; Bryan and Tempest, 1973). These reactions may have little relationship to
will or intent, and more to do with previous exposure history and personality.
Stress and annoyance from noise often do not correlate with loudness. This may suggest,
in some circumstances, other factors impact an individual's reaction to noise. A number
of reports, cited in Staples (1997), suggest that individuals with an interest in a project
and individuals who have some control over an environmental noise are less likely to find
a noise annoying or stressful.
Berglund et al. (1996) reviewed reported health effects from low frequency noise. Loud
noise from any source can interfere with verbal communication and possibly with the
development of language skills. Noise may also impact mental health. However, there are
no studies that have looked specifically at the impact of low frequency noise on
communication, development of language skills and mental health. Cardiovascular and
endocrine effects have been demonstrated in studies that have looked at exposures to
airplane and highway noise. In addition, possible effects of noise on performance and
cognition have also been investigated, but these health studies have not generally looked
at impacts specifically from low frequency noise. Noise has also been shown to impact
sleep and sleep patterns, and one study demonstrated impacts from low 'frequency noise
in the range of 72 to 85 dB(A) on chronic insomnia (Nagai et al., 1989 as reported in
Berglund et al., 1996).
Case studies have suggested that health can be impacted by relatively low levels of low
frequency noise. But it is difficult to draw general conclusions from case studies.
Feldmann and Pitten (2004)) describe a family exposed during the winter to low
frequency noise from a nearby heating plant. Reported health impacts were:
"indisposition, decrease in performance, sleep disturbance, headache, ear pressure, crawl
parasthesy [crawling, tingling or numbness sensation on the skin] or shortness of breath."
Annoyance, unpleasant sounds, and complaints
Reported health effects from low frequency stimulation are closely associated with
annoyance from audible noise. "There is no reliable evidence that infrasounds below the
hearing threshold produce physiological or psychological effects" (WHO, 1999). It has
not been shown whether annoyance is a symptom or an accessory in the causation of
15
health impacts from low frequency noise. Studies have been conducted on some aspects
of low frequency noise that can cause annoyance.
Noise complaints are usually a reasonable measure of annoyance with low frequency
environmental noise. Leventhall (2004) has reviewed noise complaints and offers the
following conclusions:
" The problems arose in quiet rural or suburban environments
The noise was often close to inaudibility and heard by a minority of people
The noise was typically audible indoors and not outdoors
The noise was more audible at night than day
The noise had a throb or rumble characteristic
The main complaints came from the 55-70 years age group
The complainants had normal hearing.
Medical examination excluded tinnitus.
" These are now recognised as classic descriptors of low frequency noise
problems."
These observations are consistent with what we know about the propagation of low
intensity, low frequency noise. Some people are more sensitive to low frequency noise.
The difference, in dB, between soft (acceptable) and loud (annoying) noise is much less
at low frequency (see Figure 4 audible range compression). Furthermore, during the
daytime, and especially outdoors, annoying low frequency noise can be masked by high
frequency noise.
The observation that "the noise was typically audible indoors and not outdoors" is not
particularly intuitive. However, as noted in a previous section, low frequencies are not
well attenuated when they pass through walls and windows. Higher frequencies
(especially above 1000 Hz) can be efficiently attenuated by walls and windows. In
addition, low frequency sounds may be amplified by resonance within rooms and halls of
a building. Resonance is often characterized by a throbbing or a rumbling, which has also
been associated with many low frequency noise complaints.
Low frequency noise, unlike higher frequency noise, can also be accompanied by
shaking, vibration and rattling. In addition, throbbing and rumbling may be apparent in
some low frequency noise. While these noise features may not be easily characterized,
numerous studies have shown that their presence dramatically lowers tolerance for low
frequency noise (Berglund et al., 1996).
As reviewed in Leventhall (2003), a study of industrial exposure to low frequency noise
found that fluctuations in total noise averaged over 0.5, 1.0 and 2.0 seconds correlated
with annoyance (Holmberg et al., 1997). This association was noted elsewhere and led
(Broner and Leventhall, 1983) to propose a 3dB "penalty" be added to evaluations of
annoyance in cases where low frequency noise fluctuated.
In another laboratory study with test subjects controlling loudness, 0.5 — 4 Hz modulation
of low frequency noise was found to be more annoying than non -modulated low
16
frequency noise. On average test subjects found modulated noise to be similarly annoying
as a constant tone 12.9 dB louder (Bradley, 1994).
B. Studies of Wind Turbine Noise Impacts on People
1. Swedish Studies
Two studies in Sweden collected information by questionnaires from 341 and 754
individuals (representing response rates of 68% and 58%, respectively), and correlated
responses to calculated exposure to noise from wind farms (Pedersen and Waye, 2004;
Pedersen, 2007; Pedersen and Persson, 2007). Both studies showed that the number of
respondents perceiving the noise from the wind turbines increased as the calculated noise
levels at their homes increased from less than 32.5 dB(A) to greater than 40 dB(A).
Annoyance appeared to correlate or trend with calculated noise levels. Combining the
data from the two studies, when noise measurements were greater than 40 dB(A), about
50% of the people surveyed (22 of 45 people) reported annoyance. When noise
measurements were between 35 and 40 dB(A) about 24% reported annoyance (67 of 276
people). Noise annoyance was more likely in areas that were rated as quiet and in areas
where turbines were visible. In one of the studies, 64% respondents who reported noise
annoyance also reported sleep disturbance; 15% of respondents reported sleep
disturbance without annoyance.
2. United Kingdom Study
Moorhouse et al. (UK Department for Business Enterprise and Regulatory Reform, 2007)
evaluated complaints about wind farms. They found that 27 of 133 operating wind farms
in the UK received formal complaints between 1991 and 2007. There were a total of 53
complainants for 16 of the sites for which good records were available. The authors of the
report considered that many complaints in the early years were for generator and gearbox
noise. However, subjective analyses of reports about noise ("like a train that never gets
there", "distant helicopter", "thumping", "thudding", "pulsating", "thumping",
"rhythmical beating", and "beating") suggested that aerodynamic modulation was the
likely cause of complaints at 4 wind farms. The complaints from 8 other wind farms may
have had "marginal" association with aerodynamic modulation noise.
Four wind farms that generated complaints possibly associated with aerodynamic
modulation were evaluated further. These wind farms were commissioned between 1999
and 2002. Wind direction, speed and times of complaints were associated for 2 of the
sites and suggested that aerodynamic modulation noise may be a problem between 7%
and 25% of the time. Complaints at 2 of the farms have stopped and at one farm steps to
mitigate aerodynamic modulation (operational shutdown under certain meteorological
conditions) have been instituted.
3. Netherlands Study
F. van den Berg et al. (2008) conducted a postal survey of a group selected from all
residents in the Netherlands within 2.5 kilometers (km) of a wind turbine. In all, 725
residents responded (37%). Respondents were exposed to sound between 24 and 54
dB(A). The percentage of respondents annoyed by sound increased from 2% at levels of
30 dB(A) or less, up to 25% at between 40 and 45 dB. Annoyance decreased above 45
dB. Most residents exposed above 45 dB(A) reported economic benefits from the
17
turbines. However, at greater than 45 dB(A) more respondents reported sleep
interruption. Respondents tended to report more annoyance when they also noted a
negative effect on landscape, and ability to see the turbines was strongly related to the
probability of annoyance.
4. Case Reports
A number of un-reviewed reports have catalogued complaints of annoyance and some
more severe health impacts associated with wind farms. These reports do not contain
measurements of noise levels, and do not represent random samples of people living near
wind turbines, so they cannot assess prevalence of complaints. They do generally show
that in the people surveyed, complaints are more likely the closer people are to the
turbines. The most common complaint is decreased quality of life, followed by sleep loss
and headache. Complaints seem to be either from individuals with homes quite close to
turbines, or individuals who live in areas subject to aerodynamic modulation and,
possibly, enhanced sound propagation which can occur in hilly or mountainous terrain. In
some of the cases described, people with noise complaints also mention aesthetic issues,
concern for ecological effects, and shadow flicker concerns. Not all complaints are
primarily about health.
Harry (2007) describes a meeting with a couple in Cornwall, U.K. who live 400 meters
from a wind turbine, and complained of poor sleep, headaches, stress and anxiety. Harry
subsequently investigated 42 people in various locations in the U.K. living between 300.
meters and 2 kilometers (1000 feet to 1.2 miles) from the nearest wind turbine. The most
frequent complaint (39 of 42 people) was that their quality of life was affected.
Headaches were reported by 27 people and sleep disturbance by 28 people. Some people
complained of palpitations, migraines, tinnitus, anxiety and depression. She also
mentions correspondence and complaints from people in New Zealand, Australia, France,
Germany, Netherlands and the U.S.
Phipps (2007) discusses a survey of 619 households living up to 10 kilometers (km; 6
miles) from wind farms in mountainous areas of New Zealand. Most respondents lived
between 2 and 2.5 km from the turbines (over 350 households). Most respondents (519)
said they could see the turbines from their homes, and 80% of these considered the
turbines intrusive, and 73% considered them unattractive. Nine percent said they were
affected by flicker. Over 50% of households located between 2 and 2.5 km and between 5
and 9.5 km reported being able to hear the turbines. In contrast, fewer people living
between 3 and 4.5 km away could hear the turbines. Ninety-two households said that
their quality of life was affected by turbine noise. Sixty-eight households reported sleep
disturbances: 42 of the households reported occasional sleep disturbances, 21 reported
frequent sleep disturbances and 5 reported sleep disturbances most of the time.
The Large Wind Turbine Citizens Committee for the Town of Union (2008) documents
complaints from people living near wind turbines in Wisconsin communities and other
places in the U.S. and U.K. Contained in this report is an older report prepared by the
Wisconsin Public Service Corporation in 2001 in response to complaints in Lincoln
County, Wisconsin. The report found essentially no exceedances of the 50 dB(A)
requirement in the conditional use permit. The report did measure spectral data
18
accumulated over very short intervals (1 minute) in 1/3 octave bands at several sites
while the wind turbines were functioning, and it is of interest that at these sites the sound
pressure level at the lower frequencies (below 125 Hz) were at or near 50 dB(A).
Pierpont (2009) postulates wind turbine syndrome, consisting of a constellation of
symptoms including headache, tinnitus, ear pressure, vertigo, nausea, visual blurring,
tachycardia, irritability, cognitive problems and panic episodes associated with sensations
of internal pulsation. She studied 38 people in 10 families living between 1000 feet and
slightly under 1 mile from newer wind turbines. She proposes that the mechanism for
these effects is disturbance of balance due to "discordant" stimulation of the vestibular
system, along with visceral sensations, sensations of vibration in the chest and other
locations in the body, and stimulation of the visual system by moving shadows. Pierpont
does report that her study subjects maintain that their problems are caused by noise and
vibration, and the most common symptoms reported are sleep disturbances and headache.
However, 16 of the people she studied report symptoms consistent with (but not
necessarily caused by) disturbance of equilibrium.
V. Noise Assessment and Regulation
1. Minnesota noise regulation
The Minnesota Noise Pollution Control Rule is accessible online at:
https://www.revisor.leg..state.mn.us/piles/?id=7030. A summary of the Minnesota
Pollution Control Agency (MPCA) noise guidance can be found online at:
http://www.pca.state.mn.us/pro<u.rams/noise.html . The MPCA standards require A -
weighting measurements of noise; background noise must be at least 10 dB lower than
the noise source being measured. Different standards are specified for day and night, as
well as standards that may not be exceeded for more than 10 percent of the time during
any hour (L10) and 50 percent of the time during any hour (L50). Household units,
including farm houses, are Classification 1 land use. The following are the Class 1 noise
limits:
Table 1: Minnesota Class 1 Land Use Noise Limits
Daytime
Nighttime
L50
L10
L50
L10
60 dB(A)
65 dB(A)
50 dB(A)
55 dB(A)
These noise limits are single number limits that rely on the measuring instrument to apply
an A -weighting filter over the entire presumed audible spectrum of frequencies (20 Hz to
20 KHz) and then integrating that signal. The result is a single number that characterizes
the audible spectrum noise intensity.
2. Low frequency noise assessment and regulation
Pedersen and Waye (2004) looked at the relationship between total dB(A) sound pressure
and the annoyance of those who are environmentally exposed to noise from different
sources. Figure 6 demonstrates the difficulty in using total dB(A) to evaluate annoyance.
Note how lower noise levels (dB(A)) from wind turbines engenders annoyance similar to
19
much higher levels of noise exposure from aircraft, road traffic and railroads. Sound
impulsiveness, low frequency noise and persistence of the noise, as well as demographic
characteristics may explain some of the difference.
Figure 6: Annoyance associated with exposure to different
environmental noises
50
45
N. 40
35
E 30
4 25
20 1'
15
•
10
5 •
i
0
•
Wind turbines
r
f
1
•
Aircraft
Road traffic
Railways
32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 65 68 70
Sound exposure (dBA)
Reprinted with permission from Pedersen, E. and K.P. Waye
(2004). Perception and annoyance due to wind turbine noise —
a dose -response relationship. The Journal of the Acoustical
Society of America 116: 3460. Copyright 2004, Acoustical
Society of America.
Kjellberg et al. (1997) looked at the ability of different full spectrum weighting schemes
to predict annoyance caused by low frequency audio noise. They found that dB(A) is the
worst predictor of annoyance of available scales. However, if 6 dB ("penalty") is added
to dB(A) when dB(C) — dB(A) is greater than 15 dB, about 71% of the predictions of
annoyance are correct. It is important to remember that integrated, transformed
measurements of SPL (e.g. dB(A), dB(C)) do not measure frequencies below 20 Hz.
While people detect stimuli below 20 Hz, as discussed in above sections, these
frequencies are not measured using an A -weighted or C -weighted meter.
The World Health Organization (WHO) recommends that if dB(C) is greater than 10 dB
more than dB(A), the low frequency components of the noise may be important and
should be evaluated separately. In addition, WHO says "[i]t should be noted that a large
proportion of low -frequency components in noise may increase considerably the adverse
effects on health." (WHO, 1999)
Many governments that regulate low frequency noise look at noise within bands of
frequencies instead of summing the entire spectrum. A study by Poulsen and Mortensen
(Danish Environmental Protection Agency, 2002) included a summary of low frequency
noise guidelines. German, Swedish, Polish, and Dutch low frequency evaluation curves
were compared (see Figure 7). While there are distinctions in how the evaluation curves
are described, generally, these curves are sound pressure criterion levels for 1/3 octaves
from about 8 Hz to 250 Hz. Exceedance in any 1/3 octave measurement suggests that the
noise may be annoying. However, note that regulations associated with low frequency
20
noise can be quite complex and the regulatory evaluations associated with individual
curves can be somewhat different.
Figure 7: 1/3 Octave Sound Pressure Level Low frequency Noise
Evaluation Curves
Sound Pressure Level. dB
100
90
80
70
60
50
40
30
20
10
0
5 20 30 50 200 300 500
10 100
Frequency, Hz
(Danish Environmental Protection Agency, 2002)
Low Frequency Evaluation Curves
Piet Sloven, NL
Swedish
—X— Polish
$ German
— A — Dutch
The Danish low frequency evaluation requires measuring noise indoors with windows
closed; SPL measurements are obtained in 1/3 octave bands and transformed using the A -
weighting algorithm for all frequencies between 10 and 160 Hz. These values are then
summed into a single metric called LPA,LF. A 5 dB "penalty" is added to any noise that is
"impulsive". Danish regulations require that 20 dB LPA,LF is not exceeded during the
evening and night, and that 25 dB LPA,LF is not exceeded during the day.
Swedish guidance recommends analyzing 1/3 octave bands between 31.5 and 200 Hz
inside a home, and comparing the values to a Swedish assessment curve. The Swedish
curve is equal to the United Kingdom (UK) Department of Environment, Food and Rural
Affairs (DEFRA) low frequency noise criterion curve for overlapping frequencies (31.5 —
160 Hz).
The German "A -level" method sums the A -weighted equivalent levels of 1/3 octave
bands that exceed the hearing threshold from 10 — 80 Hz. If the noise is not tonal, the
measurements are added. The total cannot exceed 25 dB at night and 35 dB during the
day. A frequency -dependent adjustment is applied if the noise is tonal.
In the Poulsen and Mortensen, Danish EPA study (2002), 18 individuals reported
annoyance levels when they were exposed through earphones in a controlled environment
to a wide range of low frequency environmental noises, all attenuated down to 35 dB, as
depicted in Table 2. Noise was simulated as if being heard indoors, filtering out noise at
21
higher frequencies and effectively eliminating all frequencies above 1600 Hz. Noise
levels in 1/3 octave SPLs from 8 Hz to 1600 Hz were measured and low frequencies
(below 250 Hz) were used to predict annoyance using 7 different methods (Danish,
German A -level, German tonal, Swedish, Polish, Sloven, and C -level). Predictions of
annoyance were compared with the subjective annoyance evaluations. Correlation
coefficients for these analyses ranged from 0.64 to 0.94, with the best correlation in
comparison with the Danish low frequency noise evaluation methods.
As would be expected, at 35 dB nominal (full spectrum) loudness, every low frequency
noise source tested exceeded all of the regulatory standards noted in the Danish EPA
report. Table 2 shows the Danish and Swedish regulatory exceedances of the different 35
dB nominal (full spectrum) noise.
Table 2: 35 dB(A) (nominal, 8 Hz-20KHz) Indoor Noise from Various
Outdoor Environmental Sources
Traffic Noise Dro For a Gas Turbine i Past Fe Cooling
p g rry ,Steel Factor}✓ Generator I Compressor Discotheque
Noise
Noise >- 20 Hz
67.6 dB(lin) 71.1 dB(lin) 78.4 dB(lin) 64.5 dB(lin) 72.7 dB(lin) 60.2 dB(lin) 60.3 dB(lin) 67.0 dB(lin)
35.2 dB(A) 36.6 dB(A) 35.0 dA 35.1 dB(A) 33.61 dB(A) j 36.2 dB(A) 3'6.6 dB(A) 1 33 6 dB(A)
62.9 dB(C) i 67.3 d8(C) 73.7 dB(C) 61.7 dB(C) 1 66.0 dB(C) r 58.6 dB(C)I 59.0 d8(C) 57.8 dB(C)
Danish Environmental 14.5 dB
Protection Agency
Swedish National Board ( 14.1 dB
of Health and Welfare
21.5 dB • 14.8 dB 15.0 dB 13.1 dB 16.1 dB
19.7 dB 15.9 dB 16.8 dB
14.0 dB 18.0 d6
15.5 dB 18.3 dB i 16.0 dB 10.0 dB
* includes 5 dB "penalty"
Noise adjusted to dB(lin), dB(A), dB(C) scales. Calculated exceedances of
Danish and Swedish indoor criteria. (data from Danish Environmental Protection
Agency, 2002)
In their noise guidance, the WHO (1999) recommends 30 dB(A) as a limit for "a good
night's sleep". However, they also suggest that guidance for noise with predominating
low frequencies be less than 30 dB(A).
3. Wind turbine sound measurements
Figure 8 shows examples of the SPLs at different frequencies from a representative wind
turbine in the United Kingdom. Sound pressure level measurements are reported for a
Nordex N-80 turbine at 200 meters (UK Department of Transport and Industry, 2006)
when parked, at low wind speeds, and at high wind speeds. Figure 8 also includes, for
reference, 3 sound threshold curves (ISO 226, Watanabe & Moller, 85 dB(G)) and the
DEFRA Low Frequency Noise Criterion Curve (nighttime).
22
Figure 8: Low Frequency Noise from Wind Farm: Parked, Low Wind
Speed, and High Wind Speed
Loa Frequency Noise Assessment
Wind Farm: External Noise Levels Ground Board
—0-1)I:I IIN(nlcn„n(u„r �.:1•ns
yh,nalw C M, tk,
- In.l t .nn. Ira -A.,:
— ?—tt'md F.ull. t OW % n,1 Sj 1
tn.! f .r:c: I1Th 1% mat Six..1
Coll
co
4n
lrx IM +} Ii1 1 • e, . 10 i_ In .1w ,.1,± 411 <,1 4*:' X. 100 1111 _Ire :, 11. S.M. hMl
I hill Ost.r.o I i I Crutly I toju4.11,.y (ILO,
(UK Department of Transport and Industry, 2006)
In general, sound tends to propagate as if by spherical dispersion. This creates amplitude
decay at a rate of about -6 dB per doubling of distance. However, low frequency noise
from a wind turbine has been shown to follow more of a cylindrical decay at long
distances, about -3 dB per doubling of distance in the downwind direction (Shepherd and
Hubbard, 1991). This is thought to be the result of the lack of attenuation of low
frequency sound waves by air and the atmospheric refraction of the low frequency sound
waves over medium to long distances (Hawkins, 1987).
Figure 9 shows the calculated change in spectrum for a wind farm from 278 meters to
22,808 meters distant. As one moves away from the noise source, loudness at higher
frequencies decreases more rapidly (and extinguishes faster) than at lower frequencies.
Measurement of A -weighted decibels, shown at the right of the figure, obscures this
finding.
23
Figure 9: Change in Noise Spectrum as Distance from Wind Farm
Changes
10 Turbine Wind Farm
X11 •
c
.i
0
n)
15
75
_11 •
15
11
11
1_5
25,0 500 lk
Octave Nand Centre Frequency (titl
—'—`)S m —1111— 516 m
-t— .tat', m —0-4 .1M
m-+-1s;'4m
—0-2_'NIU m
it '1 .A 1A',r0Mcd
(UK Department of Transport and Industry, 2006)
Thus, although noise from an upwind blade wind turbine is generally broad spectrum,
without a tonal quality, high frequencies are efficiently attenuated by both the
atmosphere, and by walls and windows of structures, as noted above. As a result, as one
moves away from a wind turbine, the low frequency component of the noise becomes
more pronounced.
Kamperman and James (2008) modeled indoor noise from outdoor wind turbine noise
measurements, assuming a typical vinyl siding covered 2X4 wood frame construction.
The wind turbine noise inside was calculated to be 5 dB less than the noise outside.
Model data suggested that the sound of a single 2.5 MW wind turbine at 1000 feet will
likely be heard in a house with the windows sealed. They note that models used for siting
turbines often incorporate structure attenuation of 15dB. In addition, Kamperman and
James demonstrate that sound from 10 2.5 MW turbines (acoustically) centered 2 km (1'/4
mile) away and with the nearest turbine 1 mile away will only be 6.3 dB below the sound
of a single turbine at 1000 feet (0.19 mile).
4. Wind turbine regulatory noise limits
Ramakrishnan (2007) has reported different noise criteria developed for wind farm
planning. These criteria include common practices (if available) within each jurisdiction
for estimating background SPLs, turbine SPLs, minimum setbacks and methods used to
24
assess impacts. Reported US wind turbine noise criteria range from: ambient + 10 dB(A)
where ambient is assumed to be 26 dB(A) (Oregon); to 55 dB(A) or "background" + 5
dB(A) (Michigan). European criteria range from 35 dB(A) to 45 dB(A), at the property.
US setbacks range from 1.1 times the full height of the turbine (consenting) and 5 times
the hub height (non -consenting; Pennsylvania); to 350 m (consenting) and 1000 m (non -
consenting; Oregon). European minimum setbacks are not noted.
VI. Conclusions
Wind turbines generate a broad spectrum of low -intensity noise. At typical setback
distances higher frequencies are attenuated. In addition, walls and windows of homes
attenuate high frequencies, but their effect on low frequencies is limited. Low frequency
noise is primarily a problem that may affect some people in their homes, especially at
night. It is not generally a problem for businesses, public buildings, or for people
outdoors.
The most common complaint in various studies of wind turbine effects on people is
annoyance or an impact on quality of life. Sleeplessness and headache are the most
common health complaints and are highly correlated (but not perfectly correlated) with
annoyance complaints. Complaints are more likely when turbines are visible or when
shadow flicker occurs. Most available evidence suggests that reported health effects are
related to audible low frequency noise. Complaints appear to rise with increasing outside
noise levels above 35 dB(A). It has been hypothesized that direct activation of the
vestibular and autonomic nervous system may be responsible for less common
complaints, but evidence is scant.
The Minnesota nighttime standard of 50 dB(A) not to be exceeded more than 50% of the
time in a given hour, appears to underweight penetration of low frequency noise into
dwellings. Different schemes for evaluating low frequency noise, and/or lower noise
standards, have been developed in a number of countries.
For some projects, wind velocity for a wind turbine project is measured at 10 m and then
modeled to the height of the rotor. These models may under -predict wind speed that will
be encountered when the turbine is erected. Higher wind speed will result in noise
exceeding model predictions.
Low frequency noise from a wind turbine is generally not easily perceived beyond '/2
mile. However, if a turbine is subject to aerodynamic modulation because of shear caused
by terrain (mountains, trees, buildings) or different wind conditions through the rotor
plane, turbine noise may be heard at greater distances.
Unlike low frequency noise, shadow flicker can affect individuals outdoors as well as
indoors, and may be noticeable inside any building. Flicker can be eliminated by
placement of wind turbines outside of the path of the sun as viewed from areas of
concern, or by appropriate setbacks.
25
Prediction of complaint likelihood during project planning depends on: I) good noise
modeling including characterization of potential sources of aerodynamic modulation
noise and characterization of nighttime wind conditions and noise; 2) shadow flicker
modeling; 3) visibility of the wind turbines; and 4) interests of nearby residents and
community.
VII. Recommendations
To assure informed decisions:
• Wind turbine noise estimates should include cumulative impacts (40-50 dB(A)
isopleths) of all wind turbines.
■ Isopleths for dB(C) - dB(A) greater than 10 dB should also be determined to
evaluate the low frequency noise component.
• Potential impacts from shadow flicker and turbine visibility should be evaluated.
Any noise criteria beyond current state standards used for placement of wind turbines
should reflect priorities and attitudes of the community.
VIII. Preparers of the Report:
Carl Herbrandson, Ph.D.
Toxicologist
Rita B. Messing, Ph.D.
Toxicologist
Supervisor, Site Assessment and Consultation
26
IX. References
Balaban, C. and B. Yates (2004). Vestibuloautonomic Interactions: A Teleologic
Perspective. In: The Vestibular System. Hightstein, S., R. Fay and A. Popper.
New York, Springer.
Berglund, B., P. Hassmen and R.F. Soames Job (1996). Sources and effects of low -
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29
Agenda Item: 9
MEMORANDUM
TO: Planning Commission
FROM: Dusty Finke, City Planner
DATE: July 5, 2012
MEETING: July 10, 2012 Planning Commission
SUBJ: Ordinance Amendment: Uses in Commercial Districts
Background
Recently, a potential buyer of an existing motel in the Commercial -Highway (CH) district
inquired with staff if it would be possible to expand the use. In the course of reviewing this
question, staff noted that "Hotels and Motels" is not listed within the uses allowed in the
Commercial districts. In fact, "Hotels and Motels" are only listed as an allowed use in the
Business district. Staff was unable to find any reason in the record why this use was not
included in the districts, and believes it was probably an oversight.
As a result of this question, staff briefly reviewed the uses allowed in the Commercial, Business
and Industrial districts in order to see if there were any other uses which are of similar concern.
Staff foresees similar ambiguity with a number of other uses. It appears that the main reason for
this is that the uses listed in the Business and Business Park zoning districts are more specific.
For example: "Office Uses" and "Retail Uses" are allowed in the CH zoning district. "Office
Uses," "Medical Offices," and "Banks and Financial Institutions" are allowed in the Business
district. This leaves ambiguity whether banks and medical offices were meant to be allowed in
the CH district. Staff believes these uses are very reasonable for a commercial district and were
meant to be allowed.
Ordinance Amendment
The attached ordinance adds a number of allowed uses to the Commercial districts, including:
motels/hotels, places of assembly/religious institutions, banks/financial institutions, showrooms,
medical offices, daycare facilities, physical fitness clubs/dance studios.
Staff believes these uses make sense in commercial districts and that they were likely intended to
be allowed. However, the fact that these specific uses are allowed in other districts adds
ambiguity which this amendment is meant to reduce.
Attachment
1. DRAFT Ordinance
Ordinance Amendment Page 1 of 1 July 10, 2012
Uses in Commercial Districts Planning Commission Meeting
V
CITY OF MEDINA
ORDINANCE NO.
AN ORDINANCE REGARDING ALLOWED USES IN COMMERCIAL DISTRICTS;
AMENDING SECTIONS 838.1.02, 832.2.02, and 832.3.02
The City Council of the City of Medina ordains as follows:
SECTION I. Section 838.1.02 of the code of ordinances for the City of Medina shall be
amended by adding the underlined material as follows:
Section 838.1.02. (CH) Permitted Uses. The following shall be permitted uses within the CH
district, subject to applicable provisions of the city code:
(1) Essential Services
(2) Professional and Medical Office Uses
(3) Parks and Open Space
(4) Public Services
(5) Retail Uses, except the following are not permitted uses: pet stores, pawn shops, and
adult establishments.
((LService Uses, except the following are not permitted uses: hospitals; veterinarian
clinics; adult establishments; services related to automobiles; and services delivered
off -site, including but not limited to building/lawn contractors, electrical and other
skills trades and pest control.
(7) Hotels and Motels
(8) Places of assembly, conference halls, lodres and similar uses
(9) Religious institutions
(10)Banks and financial institutions
(1 1) Showrooms
(12)Dav care facilities
(-x(13) Physical fitness clubs, dance studios, and similar uses
Section 838.1.03. (CH) Conditional Uses. The following shall be permitted within the CH
district, subject to conditional use permit approval, the specific requirements established in
Section 838.5.08, and other applicable provisions of the city code:
(1) Structures which exceed 50,000 square feet in floor area
(2) Automobile, Marine, or Trailer Sales or Rental
(3) Automobile Repair, Oil Lubrication Service Shops, Auto Body Shops
(4) Automobile Towing
(5) Car Washes or Auto Detailing
1
V
(6) Drive -through services
(7) Hospitals
(8) Indoor Recreational Uses, including but not limited to bowling alleys, dance halls,
movie theaters, and live entertainment.
(9) Motor Fuel Stations
(10) Retail and service uses which include the keeping of animals on -site such as pet
stores, veterinarian clinics, animal day cares, animal boarding, commercial kennels
and similar usesL
SECTION II. Section 838.2.02 of the code of ordinances of the City of Medina shall be
amended by adding the underlined material as follows:
Section 838.2.02. (CH -RR) Permitted Uses. The following shall be permitted uses within the
CH -RR district, subject to applicable provisions of the city code:
(1) Essential Services
(2) Professional and Medical Office Uses
(3) Parks and Open Space
(4) Public Services
(5) Retail Uses, except the following are not permitted uses: pawn shops, pet stores, and
adult establishments.
Chi LService Uses, except the following are not permitted uses: hospitals; veterinarian
clinics; adult establishments; services related to automobiles; and services delivered
off -site, including but not limited to building/lawn contractors, electrical and other
skills trades and pest control.
(7) Hotels and Motels
(8) Places of assembly, conference halls, lodges, and similar uses
(9) Religious institutions
(10)Banks and financial institutions
(1 1) Showrooms
(12) Day care facilities
(4)(13) Physical fitness clubs, dance studios, and similar uses
Section 838.2.03. (CH -RR) Conditional Uses. The following shall be permitted uses within the
CH -RR district, subject to conditional use permit approval, the specific requirements established
in Section 838.5.08, and other applicable provisions of the city code:
(1) Structures which exceed 50,000 square feet in floor area
(2) Automobile, Marine, or Trailer Sales or Rental
(3) Automobile Repair, Oil Lubrication Service Shops, Auto Body Shops
(4) Automobile Towing
(5) Motor Fuel Stations
(6) Car Washes or Auto Detailing
(7) Drive -through services
Comment [DF1]: Shown for context of other
uses allowed in the district...will be removed from
final ordinance
(8) Hospitals
(9) Indoor Recreational Uses, including but not limited to bowling alleys, dance halls,
movie theaters, and live entertainment.
(10) Retail and service uses which include the keeping of animals on -site such as pet
stores, veterinarian clinics, animal day cares, animal boarding, commercial kennels
and similar uses.
SECTION III. Section 838.3.02 of the code of ordinances of the City of Medina shall be
amended by adding the underlined material as follows:
Section 838.3.02. (CG) Permitted Uses. The following shall be permitted uses within the CG
district, subject to applicable provisions of the city code:
(1) Contractor services typically delivered off -site such as, building contractors, lawn care,
electrical, plumbing, locksmiths, and extermination or pest control.
(2) Essential services
(3) Professional and Medical Office Uses
(4) Parks and open space
(5) Public Services
(6) Retail Uses, except the following are not permitted uses: pawn shops, pet stores, and
adult establishments.
(7) Service Uses, except the following are not permitted uses: hospitals, veterinarian clinics,
adult establishments, services related to automobiles
(LWarehousing, Wholesaling, and Distributors not exceeding 10,000 square feet
(9) Places of assembly, conference halls, lodges, and similar uses
(10)Religious institutions
(1 I)Banks and financial institutions
(12) Showrooms
(13) Day care facilities
(44(14) Physical fitness clubs, dance studios, and similar uses
Section 838.3.03. (CG) Conditional Uses. The following shall be permitted uses within the CG
district, subject to conditional use permit approval, the specific requirements established in
Section 838.5.08, and other applicable provisions of the city code:
(1) Structures which exceed 50,000 square feet of floor area
(2) Assembly or Manufacturing of light industrial products, except not the following uses
and processes: leather tanning; paper manufacturing; meat slaughtering or rendering;
metal plating; Teflon coating or similar coatings requiring high temperatures; the use
of heavy or other drop forges; the use of heavy or other hydraulic surges; or the use of
any devices capable of detection at the property line.
(3) Automobile, Marine, or Trailer Sales or Rental
(4) Automobile Repair, Oil Lubrication Service Shops, Auto Body Shops
(5) Automobile Towing
Comment [DF2]: Shown for context of other
uses allowed in the district... will be removed from
tinal ordinance
(6) Car Washes or Auto Detailing
(7) Indoor Recreational Uses, including but not limited to bowling alleys, dance halls,
movie theaters, and live entertainment.
(8) Retail and service uses which include the keeping of animals on -site such as pet
stores, veterinarian clinics, animal day cares, animal boarding, commercial kennels
and similar uses.
(9) Warehousing, Wholesaling, or Distributors more than 10,000 but less than 20,000 square
feet. - - 4 Comment [DF3]: Shown for context of other
luses allowed in the disttict...wtill be removed from
final ordinance
SECTION IV. This ordinance shall become effective upon its adoption and publication.
Adopted by the Medina city council this _ day of 2012.
Attest:
T.M. Crosby, Jr., Mayor
Scott T. Johnson, City Administrator -Clerk
Published in the South Crow River on the _ day of . 2012.
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