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MEMORANDUM
TO: City Council
FROM: MacKenzie Walters,Assistant Planner
DATE: January 9, 2017
SUBJECT: Impervious Surface on Flag-Neck Lots
ISSUE
The City Code does not clarify how the impervious surface contained in the neck portion of flag lots
should be accounted for.
Examples:
Address Lot Size Neck HC Lot size HC Max
with neck Width(ft.) including minus minus HC
(sq. ft.) neck HC neck neck(%) (%)
(%)
7604 South Shore 19,602 26 24.5 17,204 21.8 25
Dr
7331 Minnewashta 46,204 55 28 38,561 24.9 25
PKY*
7351 Minnewashta 44,866 30 28.9 34,852 22.2 25
PKY*
3301 Shore Dr 188,614 60 18.9 138,483 19.8 25
6601 Horseshoe 23,958 40 29.5 18,249 31.4 25
Curve
2220 Melody Hill 30,056 34 16 24,071 14.3 25
Rd
6311 Church Rd 29,620 32 32 22,620 20 25
4158 Lakeridge Rd 59,241 28 19.8 53,941 17.9 25
1352 Ithilien 17,424 30 27.1 15,257 24.8 25
1392 Ithilien 14,810 30 31.3 13, 725 32.3 25
1385 Ithilien 23,086 30 20.3 20,804 18 25
Note: These coverage calculations are approximations from aerials.
*Part of this is likely a private road.Uncertain where road ends and driveway begins.
PH 952.227.1100• www.ci.chanhassen.mn.us• FX 952.227.1110
7700 MARKET BOULEVARD • PO BOX 147 • CHANHASSEN • MINNESOTA 55317
Impervious Surface on Flag Neck Lots-Issue Paper
January 9,2017
Page 2 of 4
BACKGROUND
The Planning Department receives calls from homeowners and contractors asking to clarify if the neck
area of flag lots counts towards a lot's area and coverage totals. In cases where the neck area is
commensurate with a private street, Section 18-57(p)(8)stipulates that neither the land area nor
impervious surface contained within the private street easement are to be included in the lot area or
coverage calculations.This same provision also specifies that once the private street ends both the
remaining area of the easement and any driveways are to be included in the calculations.
In cases where there is no private street,the ordinance is silent. Staff's practice has been to exclude the
neck area from coverage calculations.The ordinance does specify in Section 20-615 that the neck area
does not count towards the lot's minimum area,but minimum lot area and lot coverage are distinct terms
within the ordinance.This ordinance also clarifies that building setbacks shall start at the point that the lot
reaches the 100' minimum width stipulated by ordinance but does not define where the neck portion of
the lot ends.
The ordinance's definition of the term flag/neck lot, found in Section 1-2,mandates that these lots have a
30' neck in order to be classified as a flag lot.The city has numerous non-conforming lots that do not
have the required 30' neck.It is unclear if these lots should be treated as flag/neck lots or standard lots.
RELEVANT ORDINANCES
Section 1-2: Requires neck to be at least 30' wide to meet definition of flag/neck lot.*
Section 18-57@)(8): Neither the land area in private street easement or nor its impervious surface are
included in the lot area or lot coverage calculation;however, once the private street ends the area of its
easement and the driveway are included.
Section 18-57(R)(1-3): Stipulates the conditions under which a variance for the creation of new flag lots
may be allowed. Specifically,they must be necessitated by prevailing development patterns,a public or
private street system must be unnecessary,and/or it will serve to protect the natural environment.
Section 20-615: Sets Lot requirements for neck or flag lots as 15,000 sq. ft. excluding the neck, front lot
width of 100' at building setback line,and front yard setback shall be measured from the point where the
lot achieves 100'.The code does not define where the neck ends, only were the lot setback should be
measured from.**
Section 20-1122(1):Neck or flag lots are exempted from normal driveway setbacks. Starting at 20' from
the front property line driveways may be setback a minimum of 5' from the side property line or the
distance of an existing drainage and utility easement.
Section 20-1122(8): Allows the City Engineer to approve reduced driveway setbacks for neck or flag lots.
*The ordinance was amended to require to 30' minimum width in 2003.
**Staff's practice has been to consider the neck to end at the point where the lot achieves 100'.
Impervious Surface on Flag Neck Lots -Issue Paper
January 9,2017
Page 3 of 4
ANALYSIS
Issue: Should land area and impervious surface on necks be included or excluded from coverage
calculations?
Discussion: Excluding the land area and impervious surface on necks would be consistent with how
private streets,which serve a similar function, are treated and with how lot area is calculated.Including
the land and impervious surface areas in coverage calculation would likely generate numerous variance
requests as homeowners argued the unique shape of their parcel created a hardship and unreasonably low
amounts of useable lot area.The shape of the parcel would only be considered a hardship in cases where
the flag lot itself is not a variance,i.e.nonconforming lots created before 2003.
Issue: Where does the neck end for the purpose of lot coverage calculations?
Discussion: On flag lots that follow the stipulated 30'+neck with parallel lot lines that connect to a
rectangular lot with a 100'+width it is visually clear where the neck ends; however,many lots do not
follow this form. For lots where the neck gradually widens, it is not clear where the neck ends and the lot
begins.This is especially relevant for properties where the driveway within the expanding neck widens
beyond what is necessary for access to the property.This can result in large amounts of impervious
surface being excluded from lot coverage calculations.
Issue:Neck lots usually have levels of impervious surface well above the 25%normally allowed in RSF
districts.
Discussion:The amount of impervious surface on a property has substantial implications for stormwater
management. The city engineers its stormwater management systems to handle the runoff generated by
single family homes with up to 25%hard cover.The neck area of flag lots almost always exceeds that
threshold.For example,even a 10' driveway on a regulation 30' neck means that a portion of the property
will have 33%lot coverage. The code currently accommodates a 20' driveway within a 30' neck which
results in 66%lot coverage. On lots where the neck widens beyond the 30' minimum a homeowner could
theoretically build a wider driveway with an even higher ratio of impermeable to permeable surface. In
the most extreme case a homeowner could build a 50' driveway in a 60' neck creating 83.3%lot coverage
within the neck.The amount of stormwater generated by these parts of a property can be substantial as
necks are often over 100' long. It may be advisable to include the neck lot's predicted impact on the lot's
stormwater generation as part of the variance criteria used to evaluate requests to create flag lots.The
maximum width of driveways within a lot's neck should also be stipulated.
Issue: If flag lots' impervious surfaces are not included with the properties' coverage calculations,how
should that impervious surface be accounted for?
Discussion: As discussed above,the neck areas of neck/flag lots can involve large amounts of impervious
surface and create stormwater management issues. It is important to have accurate projections of a
subdivisions total imperious surface in order to effectively manage stormwater.A potential solution could
be to stipulate a maximum 33%driveway width for the length of the neck and include that total in the
tabulation of the subdivision's streets and other impervious surfaces.
Impervious Surface on Flag Neck Lots -Issue Paper
January 9,2017
Page 4 of 4
Issue: There are numerous parcels of the neck/flag lot type that do not meet the ordinance's definition of a
flag lot because they have a neck that is less than 30' wide. Should they be treated as flag lots or normal
lots?
Discussion: Either way these lots will be non-conforming lots;however,it may make sense to grandfather
them in as flag lots.This would provide consistent treatment of parcels with similar features.Treating
them as normal lots would create all of the complications listed above with including the neck's area in
impervious surface calculations.
ALTERNATIVES
1) Do nothing. Staff's current practice of excluding the necks and impervious surface within necks
from coverage calculations seems in line with the intent of the ordinance.However,this may lead
to underestimating the amount of hardcover in the city.
2) Amend the relevant sections of the City Code to clarify how necks are to be incorporated or
omitted from coverage calculations and how much impervious surface they are allowed.This
would help make sure that all properties are held to the same standard,that homeowners and
developers understand how much impervious surface they have to work with on a parcel, allow
the city to more effectively manage the amount of impervious surface present, and require
stormwater management with the neck area unless it is included in the street stormwater system.
Staff recommends alternative two because it adds clarity and transparency to the city's lot coverage
calculations,allows us to account for all impervious surface within the city,and allows for better
management of the city's stormwater.
RECOMMENDATION
Staff is requesting feedback and direction from the Planning Commission on how best to address these
concern.
ATTACHMENTS
Attachment 1: Full text of cited City Ordinances.
Attachment 2: Ideal Flag Lot
Attachment 3: Typical Flag
Attachment 4: Flag with Widening Drive
Attachment 5: Percentage of HC of Neck
G:\PLAN\City Code\Issue Paper\Flag Lots\Issue Paper HC on Flag-Neck lots_CC
Attachment 1: Full text of cited City Ordinances
Sec. 1-2.-Rules of construction and definitions.
• Lot,flag/neck means a lot that does not provide the full required frontage on a public right-of-way,
but rather is served by a narrow"neck" of land that extends to the street. To meet the definition the
neck must be at least 30 feet wide. The lot width on neck or flag lots and lots accessed by private
streets shall be 100 feet as measured at the front building setback line. The location of these lots is
conceptually illustrated below. (18,20)
Neck/ Flag Lot:
Front Lot Line
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Sec. 18-57.-Streets.
(p)Private street standards. If the use of a private street is to be allowed,it shall be subject to the
following standards:
(8)Private streets serving residential development with a density equal to or greater than four
units per acre,commercial,office,office industrial,or mixed-use districts,must be located
within a strip of property at least 40 feet wide extending out to the public right-of-way or covered
by a 40-foot wide easement that is permanently recorded over all benefited and impacted parcels.
Neither the area within the easement for the private street,nor the impervious surface of the
1
private street shall be included within the calculation of the lot area or lot coverage of the lot in
which the easement is located. Once the private street terminates,the area of the easement and
impervious surface of the driveway shall be included in the calculation of lot area and lot
coverage for the lot.
Sec. 20-615. -Lot requirements and setbacks.
The following minimum requirements shall be observed in an"RSF"District subject to additional requirements,
exceptions and modifications set forth in this chapter and chapter 18:
(1)The minimum lot area is 15,000 square feet. For neck or flag lots,the lot area requirements shall be
met after the area contained within the"neck"has been excluded from consideration.
(2)The minimum lot frontage is 90 feet,except that lots fronting on a cul-de-sac "bubble" shall be 90
feet in width at the building setback line.The location of this lot is conceptually illustrated below.
Lots vihere.frontage is
measuredat the setback lute.
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Frontage Measured at Setback Line
(3)The minimum lot depth is 125 feet.
(4)Lot width on neck or flag lots and lots accessed by private streets shall be 100 feet as measured at
the front building setback line.The location of these lots is conceptually illustrated below.
2
NECK/FLAG LOTS
FRONT LOT LINE
STREET
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100' LOT WIDTH 1 1
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Neck/Flag Lots
(5)The maximum lot coverage for all structures and paved surfaces is 25 percent.
(6)The setbacks are as follows:
a. For front yards, 30 feet.
b. For rear yards, 30 feet.
c. For side yards, ten feet.
(7) The setbacks for lots served by private streets and/or neck lots are as follows:
a. For front yard, 30 feet. The front yard shall be the lot line nearest the public right-of-way that
provides access to the parcel. The rear yard lot line is to be located opposite from the front lot
line with the remaining exposures treated as side lot lines. On neck lots the front yard setback
shall be measured at the point nearest the front lot line where the lot achieves a 100-foot
minimum width.
b. For rear yards, 30 feet.
c. For side yards, ten feet.
(8) The maximum height is as follows:
a. For the principal structure, three stories/35 feet.
b. For accessory structures, 20 feet.
3
Sec. 20-1122. -Access and driveways.
The purpose of this section is to provide minimum design criteria, setback and slope standards for vehicular use.
The intent is to reduce interference with drainage and utility easements by providing setback standards;
reduce erosion by requiring a hard surface for all driveways; to limit the number of driveway access points
to public streets and to direct drainage toward the street via establishment of minimum driveway slope
standards.Parking and loading spaces shall have proper access from a public right-of-way. The number and
width of access drives shall be located to minimize traffic congestion and abnormal traffic hazard. All
driveways shall meet the following criteria:
(1) Driveways shall be setback at least ten feet from the side property lines, except on lots that
access off of a cul-de-sac "bubble",neck or flag lot where the lot frontage may prohibit meeting
the side yard setback requirement. Beginning 20 feet from the front property line,driveways
may be setback a minimum of five feet from the side property line or the distance of the
existing drainage and utility easement on the particular lot or parcel. Encroachment into a side
yard drainage and utility easement must be reviewed and approved by the city and may require
an encroachment agreement.
[...]
(8)Driveway setbacks may be reduced subject to approval by the city engineer and the
following criteria:
a.The driveway will not interfere with any existing drainage swale or easement in which a
utility is contained;
b. Shall require an easement encroachment agreement from the engineering department;
c.The driveway must be designed to maintain stormwater drainage runoff on the property to
ensure that it will not cause runoff onto adjacent properties;
d. Snow storage may not be placed on adjacent properties;and
e.Lot frontage on lots that access off of a cul-de-sac"bubble",neck or flag lot do not permit
adequate driveway access width or side yard setback.
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