1f. Approval of Amendment to City Code, Chapters 1, 7, 13, 18, 19 & 20 as a Result of Adoption of the Second Generation Surface Water Management Plan
CITY OF
CHANHASSEN
7700 Market Boulevard
PO Box 147
Chanhassen, MN 55317
Administration
Phone: 952.227.1100
Fax: 952.227.1110
Building Inspections
Phone: 952.227.1180
Fax: 952.227.1190
Engineering
Phone: 952.227.1160
Fax: 952.227.1170
Finance
Phone: 952.227.1140
Fax: 952.227.1110
Park & Recreation
Phone: 952.227.1120
Fax: 952.227.1110
Recreation Center
2310 Coulter Boulevard
Phone: 952.227.1400
Fax: 952.227.1404
Planning &
Natural Resources
Phone: 952.227.1130
Fax: 952.227.1110
Public Works
1591 Park Road
Phone: 952.227.1300
Fax: 952.227.1310
Senior Center
Phone: 952.227.1125
Fax: 952.227.1110
Web Site
www.ci.chanhassen.mn.us
l-P.
MEMORANDUM
To:
Todd Gerhardt, City Manager
Lori Haak:, Water Resources Coordinator ~
February 12,2007 1"Y
From:
Date:
Re:
Adoption of Code Revisions Resulting from Adoption of Second
Generation Surface Water Management Plan (SWMP)
REQUESTED ACTION
Staff recommends the City Council adopt a motion adopting ordinances
amending Chapters 1, 7, 13, 18, 19 and 20 of the City Code to bring the code
into compliance with the City's Second Generation Surface Water
Management Plan. Staff also recommends the City Council adopt a motion
approving summary ordinances for Chapters 1, 18, 19 and 20 for publication
purposes.
A simple majority VQte of City Council. members present is required to adopt
the amendments,. .however, a 4/5ths vote is requiredfor approval of the
summary ordinances for publication purposes.
EXECUTIVE SUMMARY
At the regular Council meeting on January 8, 2007, City staff presented the
recommended ordinances that would revise City Code to bring it into
compliance with the City's Second Generation Surface Water Management
Plan. The City Council requested the opportunity to discuss the recommended
changes at a work session. Two main items were brought up for discussion at
the January 22nd Work Session: 1. The recommendations regarding
impervious surface; and 2. The proposed wetland buffer and setback
requirements.
The Council requested at the January 22nd Work Session that the
recommended code revisions not related to the discussions on impervious
surface and wetland buffer and setback requirements be brought forward for
adoption at the next City Council meeting. The Council further requested that
discussions on the two aforementioned items be continued at a future work
session. These items are currently scheduled for discussion at the February 26
work session.
The City of Chanhassen . A growing community with clean lakes, quality schools, a charming downtown, thriving businesses, winding trails, and beautiful parks. A great place to live, work, and play.
Code Revisions Resulting from Second Generation SWMP
February 12, 2007
Page 2 of 2
Because the strikethrough/bold versions of the proposed revisions was supplied in the
January 8th City Council packet, they are not attached. However, they are available upon
request.
RECOMMENDA TION
Staff recommends that the City Council adopt the following motions:
"The City Council adopts ordinances amending Chapters 1, 7, 13, 18, 19 and 20 of the
City Code to bring the code into compliance with the City's Second Generation Surface
Water Management Plan."
and
"The City Council approves the summary ordinances for Chapters 1, 18, 19 and 20 for
publication purposes."
A TT ACHMENTS
1. .Summary Ordinances for Chapters 1, 18, 19 and 20.
2. OrdinanGes amending Chapters 1, 7, 13, 18, 19 and 20.
G:\ENG\Lori\Surface Water\2006 SWMP Update\Code Updates\CC 021207\021207 CC Exec Summary.doc
CITY OF CHANHASSEN
CARVER AND HENNEPIN COUNTIES, MINNESOTA
SUMMARY OF ORDINANCE NO._,
AN ORDINANCE AMENDING
CHAPTER 1 OF THE CHANHASSEN CITY CODE
GENERAL PROVISIONS.
The purpose of this code amendment is to revise and update Section 1-2 of the City of
Chanhassen including:
· Adding definitions that appear in the Second Generation Surface Water Management Plan,
including: Boardwalk; Erosion Control; GIS; Hardcover; MPCA; NPDES permit; Sediment
Control; Storm Water Pollution Prevention Plan; and Surface Water Management Plan.
A printed copy of Ordinance No. _ is available for inspection by any person during
regular office hours at the office of the City Manager/Clerk.
PASSED, ADOPTED, AND APPROVED FOR PUBLICATION this _ day of
2007, by the City Council of the City of Chanhassen.
(Published in the Chanhassen Villager on
).
CITY OF CHANHASSEN
CARVER AND HENNEPIN COUNTIES, MINNESOTA
SUMMARY OF ORDINANCE NO._,
AN ORDINANCE AMENDING
CHAPTER 18 OF THE CHANHASSEN CITY CODE
SUBDIVISIONS.
The purpose of this code amendment is to revise and update the zoning code of the City of
Chanhassen including:
· Removing the requirement for replacement of four inches of topsoil in disturbed areas
· Replacing the phrase "Best Management Practices Handbook" with "Surface Water
Management Plan"
· Updating the reference from the February 1994 Surface Water Management Plan to the August
2006 Surface Water Management Plan
· Including a reference to subpart (c) 3 of Section 4-30 where the water quality and water
quantity connection charges are set
A printed copy of Ordinance No. _ is available for inspection by any person during
regular office hours at the office of the City Manager/Clerk.
PASSED, ADOPTED, AND APPROVED FOR PUBLICATION this _ day of
2007, by the City Council of the City of Chanhassen.
(Published in the Chanhassen Villager on
).
CITY OF CHANHASSEN
CARVER AND HENNEPIN COUNTIES, MINNESOTA
SUMMARY OF ORDINANCE NO._,
AN ORDINANCE AMENDING
CHAPTER 19 OF THE CHANHASSEN CITY CODE
WATER, SEWERS AND SEWAGE DISPOSAL
The purpose of this code amendment is to revise and update the water, sewers and sewage
disposal code of the City of Chanhassen including:
· Prohibiting unlawful discharges to storm sewers
· Restructuring the surface water management article
· Incorporating the city's development standards into the surface water management article
· Requiring landlocked storm water basins to hold back-to-back tOO-year rain events
· Requiring additional storm water management techniques within the Assumption Creek
subwatershed to mitigate impacts of development to that resource
A printed copy of Ordinance No. _ is available for inspection by any person during
regular office hours at the office of the City Manager/Clerk.
PASSED, ADOPTED, AND APPROVED FOR PUBLICATION this _ day of
2007, by the City Council of the City of Chanhassen.
(Published in the Chanhassen Villager on
).
CITY OF CHANHASSEN
CARVER AND HENNEPIN COUNTIES, MINNESOTA
SUMMARY OF ORDINANCE NO. _,
AN ORDINANCE AMENDING
CHAPTER 20 OF THE CHANHASSEN CITY CODE
ZONING.
The purpose of this code amendment is to revise and update the zoning code of the City of
Chanhassen including:
· Replacing the phrase "Best Management Practices Handbook" with "Surface Water
Management Plan"
· Prohibiting impervious surfaces within the bluff setback unless otherwise authorized
A printed copy of Ordinance No. _ is available for inspection by any person during
regular office hours at the office of the City Manager/Clerk.
PASSED, ADOPTED, AND APPROVED FOR PUBLICATION this _ day of
2007, by the City Council of the City of Chanhassen.
(Published in the Chanhassen Villager on
)
CITY OF CHANHASSEN
CARVER AND HENNEPIN COUNTIES, MINNESOTA
ORDINANCE NO.
AN ORDINANCE AMENDING CHAPTER 1
CHANHASSEN CITY CODE, GENERAL PROVISIONS
THE CITY COUNCIL OF THE CITY OF CHANHASSEN, MINNESOTA ORDAINS:
Section 1. Section 1-2 of the City Code, City of Chanhassen, Minnesota, is hereby amended to
include the following terms and their definitions:
Boardwalk means a linear structure extending across wetlands or lakes that is not supported by
posts or poles, but floats or rests upon floats without causing detrimental impacts to the wetland
or lake. (20)
Erosion control means best management practices employed to prevent erosion including, but
not limited to: soil stabilization practices, limited grading, mulch, temporary or permanent
cover, and construction phasing as defined in the MPCA General Construction Permit. (7,19)
GIS means Geographic Information System, such as ArcView. (20)
Hardcover see Impervious surface.
MPCA means the Minnesota Pollution Control Agency.
NPDES permit means the Minnesota Pollution Control Agency's (MPCA's) National Pollutant
Discharge Elimination System (NPDES) Phase II Municipal Separate Storm Sewer System
(MS4) permit.
Sediment control means best management practices employed to prevent sediment from leaving
site including, but not limited to: silt fence, sediment traps, earth dikes, check dams, subsurface
drains, pipe slope drains, storm drain inlet protection and temporary or permanent sediment
basins as defined in the MPCA General Construction Permit. (7, 19)
Storm Water Pollution Prevention Plan (SWPPP) means a plan for stormwater discharge that
includes erosion prevention measures and sediment controls that, when implemented, will
decrease soil erosion on a parcel of land and decrease off-site nonpoint pollution, as defined in
the MPCA General Construction Permit.
Surface Water Management Plan (SWMP) means the most recently adopted version of the
Chanhassen Surface Water Management Plan.
1
Section 2. This ordinance shall be effective immediately upon its passage and publication.
PASSED AND ADOPTED this _ day of _,200_, by the City Council of the City
of Chanhassen, Minnesota
Todd Gerhardt, City Manager Thomas A. Furlong, Mayor
(Published in the Chanhassen Villager on )
2
CITY OF CHANHASSEN
CARVER AND HENNEPIN COUNTIES, MINNESOTA
ORDINANCE NO.
AN ORDINANCE AMENDING CHAPTER 7
CHANHASSEN CITY CODE, BUILDINGS AND BUILDING REGULATIONS
THE CITY COUNCIL OF THE CITY OF CHANHASSEN, MINNESOTA ORDAINS:
Section 1. The City Code, City of Chanhassen, Minnesota, is hereby amended by adding a
section to be numbered Section 7-19 (20) which shall read as follows:
Location and type of erosion and sediment control measures to be installed by permit holder.
Section. Section 7-22 of the City Code, City of Chanhassen, Minnesota, is hereby amended to
read as follows:
(a) A satisfactory erosion and sediment control plan and grading plan consistent with the city's
Surface Water Management Plan must be approved by the city engineer or designee before a
building permit is issued for construction, if the construction will result in disturbing the soil.
The erosion and sediment control plan shall be illustrated and summarized, by the applicant at
the time of application. Guidance documents shall be listed in the Surface Water Management
Plan and on the city website.
To guarantee compliance with the plan a $500.00 cash escrow or letter of credit, satisfactory to
the city, shall be furnished to the city before a building permit is issued. The escrow amount may
be greater than $500.00 if, after review of the site, the city deems it necessary to require a greater
amount to guarantee compliance. The maximum escrow allowable per parcel is $5,000.00 per
acre. The city may use the escrow or draw upon the letter of credit to reimburse the city for any
labor or material costs it incurs in securing compliance with the plan or in implementing the
plan. If the city draws on the escrowed funds, no additional building permits shall be issued until
the pre-draw escrow balance has been restored. The city shall endeavor to give notice to the
owner or developer before proceeding, but such notice shall not be required in an emergency as
determined by the city.
(b) The grading and erosion control plan must be consistent with the approved grading plan for
the plat in which the property is located, if any.
(c) Every effort shall be made to minimize disturbance of existing ground cover. No grading or
filling shall be permitted within 40 feet of the ordinary high water mark of a water body unless
specifically approved by the city.
1
(d) Every effort shall be made during the building permit application process to determine the
full extent of erosion control required. However, the city engineer may require additional
controls to correct specific site related problems as normal inspections are performed.
(e) All erosion control noted on the approved plan shall be installed prior to the initiation of any
site grading. Noncompliance with the grading and erosion control plan shall constitute grounds
for an order from the city engineer to halt all construction.
(f) All construction activity that results in disturbance of the ground shall comply with the city's
Surface Water Management Plan.
(g) If the erosion and sediment control measures have not been installed or maintained properly,
the city reserves the right to stop further work.
(h) Temporary or permanent erosion control shall be installed on all exposed soils not actively
being graded consistent with conditions of NPDES construction permit or as detailed in the 2005
MN DOT construction specification handbook, specification 2575.
Section 3. The City Code, City of Chanhassen, Minnesota, is hereby amended by adding a
section to be numbered 7-34 (4), which shall read as follows:
Obtain all applicable permits as required and work within the requirements of the permits.
Section 4. Section 7-35 (b) (12) of the City Code, City of Chanhassen, Minnesota, is hereby
amended to read as follows:
Plans for drainage, erosion and sediment control and dust control.
Section 5. This ordinance shall be effective immediately upon its passage and publication.
PASSED AND ADOPTED this _ day of _, 200_, by the City Council of the City
of Chanhassen, Minnesota
Todd Gerhardt, City Manager Thomas A. Furlong, Mayor
(Published in the Chanhassen Villager on )
2
CITY OF CHANHASSEN
CARVER AND HENNEPIN COUNTIES, MINNESOTA
ORDINANCE NO.
AN ORDINANCE AMENDING CHAPTER 13
CHANHASSEN CITY CODE, NUISANCES
THE CITY COUNCIL OF THE CITY OF CHANHASSEN, MINNESOTA ORDAINS:
Section 1. Section 13-2 (a) (15) of the City Code, City of Chanhassen, Minnesota, is hereby
amended to read as follows:
The pollution of any public well, stream, river, lake, wetland, storm sewer or body of water by
chemical, organic, industrial, agricultural, commercial, residential, sewage, yard, construction
and animal wastes.
Section 2. This ordinance shall be effective immediately upon its passage and publication.
PASSED AND ADOPTED this _ day of _,200_, by the City Council of the City
of Chanhassen, Minnesota
Todd Gerhardt, City Manager Thomas A. Furlong, Mayor
(Published in the Chanhassen Villager on )
CITY OF CHANHASSEN
CARVER AND HENNEPIN COUNTIES, MINNESOTA
ORDINANCE NO.
AN ORDINANCE AMENDING CHAPTER 18
CHANHASSEN CITY CODE, SUBDIVISIONS
THE CITY COUNCIL OF THE CITY OF CHANHASSEN, MINNESOTA ORDAINS:
Section 1. Section 18-62 (a) of the City Code, City of Chanhassen, Minnesota, is hereby
amended to read as follows:
The development shall conform to the topography and soils to create the least potential for soil
erOSIon.
Section 2. Section 18-62 (d) of the City Code, City of Chanhassen, Minnesota, is hereby
amended to read as follows:
Subdivision development shall conform to the city's Surface Water Management Plan.
Section 3. Section 18-63 (a) of the City Code~ City of Chanhassen, Minnesota, is hereby
amended to read as follows:
All subdivisions shall comply with the city's surface water management plan dated August 2006,
which is incorporated herein by this reference.
Section 4. Section 18-63 (b) of the City Code, City of Chanhassen, Minnesota, is hereby
amended to read as follows:
In accordance with the city's surface water management plan as a condition of subdivision
approval, subdividers shall pay a water quality and water quantity connection charge. The charge
shall be based upon the gross area of the subdivision less the area to be dedicated to the city for
ponding, parks and wetland, and right-of-way for state highways, county roads, and local arterial
roadways. The connection charges per acre for water quality and water quantity are outlined in
subpart (c) 3 of Section 4-30.
The subdivision will be given a credit for on-site stormwater quality improvements that are
designed to treat runoff from the subdivision to NURP standards. The credit will be calculated
using the following formula: The per acre water quality connection charge will be multiplied by
the on-site drainage area for water quality treatment facilities. This value will then be multiplied
by 50 percent. The subdivision will also be given a credit for on-site storm water quality
improvements that are oversized to treat runoff from property outside the subdivision to NURP
1
standards. The credit will be calculated using the following formula: The per acre water quality
connection charge will be multiplied by the off-site drainage area for water quality treatment
facilities. This value will then be multiplied by 50 percent. Credit will not be granted if the
stormwater from contributing off-site areas is already treated to NURP standards. The water
quality connection charges that correspond to the land uses that contribute to the stormwater
ponds will be used to calculate credits.
The charge for lots oversized due to individual on-site sewage disposal and water systems will be
reduced to the charge that would be imposed on a one-half-acre lot. An additional charge will
then be imposed if the lot is further subdivided less a credit for the charge previously paid. The
charge shall be paid in cash before the subdivision is approved by the city unless the city and
subdivider agree that the charge may be assessed against the property. Property being subdivided
shall be exempt from the water quality and water quantity connection charges imposed by this
section if the charges were paid or assessed in conjunction with a previous subdivision of the
property and if the property is not being zoned to a classification with a higher charge.
Section 5. This ordinance shall be effective immediately upon its passage and publication.
PASSED AND ADOPTED this _ day of _, 200_, by the City Council of the City
of Chanhassen, Minnesota
Todd Gerhardt, City Manager Thomas A. Furlong, Mayor
(Published in the Chanhassen Villager on )
2
CITY OF CHANHASSEN
CARVER AND HENNEPIN COUNTIES, MINNESOTA
ORDINANCE NO.
AN ORDINANCE AMENDING CHAPTER 19
CHANHASSEN CITY CODE, WATER, SEWERS AND SEW AGE DISPOSAL
THE CITY COUNCIL OF THE CITY OF CHANHASSEN, MINNESOTA ORDAINS:
Section 1. The City Code, City of Chanhassen, Minnesota, is hereby amended by adding
sections to be numbered 19-101 through 19-102, which shall read as follows:
Sec. 19-101. Unlawful discharge.
As provided in this Article and the city's NPDES permit, it shall be unlawful to discharge to any
storm sewer any pollutant waters.
Sec. 19-102. Regulations for use of storm sewer.
(a) No person shall throw, deposit, place, leave, maintain or keep or permit to be thrown,
placed, left, maintained or kept, any refuse, rubbish, garbage or any other discarded or
abandoned objects, articles, or accumulations, in or upon any street, alley, sidewalk, storm drain,
inlet, catch basin, drainage structure, business place, or upon any public or private plot of land so
that the same might be or become a pollutant, except in containers, recycling bags, or other
lawfully established waste disposal facility.
(b) No person shall intentionally dispose of grass, leaves, dirt, or other landscape debris into a
lake, wetland, storm water pond, wetland buffer strip, street, road, alley, catch basin, culvert,
curb, gutter, inlet, ditch, natural watercourse, ravine, flood control channel, canal, storm drain or
any fabricated natural conveyance.
(c) No person shall leave, deposit, discharge, dump, or otherwise expose any chemical or septic
waste in an area where discharge to streets or the storm sewer system may occur.
(d) No person shall use any storm sewer connection to intentionally convey non-storm water to
the storm water system.
(e) Objects, such as motor vehicle parts, containing grease, oil or other hazardous substances,
and unsealed receptacles containing hazardous materials, shall not be stored outdoors.
(f) Fuel and chemical residue or other types of potentially harmful material, such as animal
waste, garbage or batteries, which is located outdoors shall be removed as soon as possible and
disposed of properly. Household hazardous waste shall not be placed in a trash container.
1
(g) No person shall maliciously, willfully or negligently break, damage, destroy, uncover, deface
or tamper with any structure, appurtenance or equipment which is a part of the city storm sewer
system.
(h) The following activities shall be determined exempt from the provisions listed in this article:
(1) City staff or city contractors during the course of conducting maintenance activities; and
(2) Metropolitan Mosquito Control District during the course of conducting mosquito control
activities.
Section 2. Sections 19-140 through 19-148 of the City Code, City of Chanhassen, Minnesota,
are hereby repealed.
Section 3. The City Code, City of Chanhassen, Minnesota, is hereby amended by adding
sections to be numbered 19-140 through 19-146, which shall read as follows:
ARTICLE VII. SURFACE WATER MANAGEMENT.
Sec. 19-140. Purpose.
The purpose of this ordinance is to implement standards to achieve the goals and policies set
forth in the city's Surface Water Management Plan in order to preserve, protect and improve the
city's surface water resources.
Sec. 19-141. Development standards.
These development standards shall be reflected in plans prepared by developers and/or project
proposers in the design and layout of site plans, subdivisions and water management features.
Sec. 19-142. Plans required.
All plans shall be reviewed and stamped" Approved by the City Engineer" and all applicable
permits must be obtained prior to commencing construction. For all newly constructed storm
water facilities (ponds, retention areas, infiltration basins, storm sewer, etc.) or existing facilities
that are modified, as-built plans shall be prepared by the developer. As-built plans shall be
signed and cel1ified by a licensed professional engineer in the State of Minnesota and record
drawings shall be provided to the city. Standard details for many typical storm structures (e.g.,
storm sewer, outlet structures, catch basins, sump manholes, etc.) are available on the city's
website.
Sec. 19-143. General elements.
(a) Hydrologic Analysis
1. Storm distributions and storm volumes for hydrologic analysis shall be based upon
Hershfield, D.M., 1961, Rainfall Frequency Atlas of the United States for Durations of 30
2
Minutes to 24 Hours and Return Periods from 1 to 100 Years, Technical Publication No. 40
(TP-40).
2. Design of major facilities (e.g., ponds, detention areas, retention areas) shall be based on
the U.S.D.A. NRCS methods, 1 DO-year return period, 24-hour duration, type II distribution
with average soil moisture conditions (AMC-2). The analysis of flood levels, storage
volumes and discharge rates for detention basins shall utilize the design storm/freeboard
evaluation storm concept.
3. Minor drainage systems (storm sewer) shall be analyzed and designed to protect for the 10
year frequency rainfall, and shall be evaluated for the 100-year frequency rainfall. Full pipe
flow analysis shall be used unless special conditions can be demonstrated to consider
pressure flow.
4. The Rational Method is the accepted design method for the design of minor systems
(storm sewer). The preferred method of design would be a method utilizing a hydrograph
approach with factors for land use and soil moisture conditions. NRCS methodology is not
acceptable for minor system design unless approved by the City Engineer.
5. Landlocked storm water basins shall be designed to hold back-to-back 100-year storms.
For landlocked areas, available freeboard and infiltration capacity of in-place soils should be
analyzed (if analyzed for unfrozen soil conditions).
(b) Peak Discharge Rates
1. Peak storm water discharge rates and storage volumes from any drainage area, watershed,
subwatershed, detention basin, wetland or conveyor shall be consistent with the values shown
in this plan for the 100- year storm event.
2. No increase in peak discharge rate may result from the proposed project for the 1 or 2-year
stOlID, the 10-year storm and the 100-year storm event. Variances may be allowed if
computations can be provided which demonstrate no adverse downstream effects will result
from the proposed system. Cumulati ve storm depths for the required events are:
a) 2- Year = 2.8 inches
b) 10-Year = 4.2 inches
c) IOO-Year = 6.0 inches
(c) General Faci tity Planning
1. Developments shall maximize preservation and use of natural detention areas and regional
detention areas shall be used to the greatest practical extent. Multiple purpose detention areas
are encouraged to maximize maintenance efficiency within proposed developments while
providing the proper flood control and water quality features.
2. The construction of detention basins will involve the direct participation of individual
developers. Where regional basins serve multiple properties and may lie outside of the
ownership of the specific development, the City and WDs will take an active role on
3
implementing policy. Because the basis for the hydrology is based on the developer's grading
plan, the developer is required to obtain and submit the cettification of a licensed engineer
that the detention areas are constructed to the specifications of the approved design.
Sec. 19-144. Major facility design elements.
(a) Facility Design Criteria
(1) For design or modification of storm water facilities, the following criteria shall be
followed:
a. All hydrologic data and computations shall be based on NRCS (formerly SCS)
methodology. Computer modeling may be completed using HydroCAD, TR20/TR55,
SWMM or comparable City-approved modeling software.
b. Hydraulic computations shall be completed using the rational method for storm sewer
design, or in commonly used software packages including FHW A HY -8, Geopack, Eagle
Point or SWMM compatible software.
c. Water quality modeling shall be completed using Pondnet, P8 Urban Catchment
Model, SLAMM or comparable software.
d. Outlet structure d~signs shall provide rate controls that limit post-project rates to not
exceed existing rates for 1 or 2-year, 10-year, 100-year events and 100-year/10-day
snowmelt.
e. An emergency overflow spillway shall be identified and designed to convey storm
flows from events greater than the 100-year event. Extreme events (on the order of a 10.0
inch event) shall be analyzed to ensure the emergency overflow spillway will function as
designed. An emergency overflow shall be set an elevation at least 1.5 feet below the
lowest adjacent low building elevation.
f. Maximum 3: 1 (H:V) side slopes (see diagram that follows).
g. 10:1 (H:V) safety bench from normal water level (see diagram that follows).
h. For basins intended to have permanent water levels, a minimum of four feet of
standing water (dead storage depth) and a maximum of ten feet shall be provided.
i. Proper allowance shall be made for future access and maintenance. Easements shall be
greater than or equal to 20 feet wide.
j. Separation between the inlet(s) and outlet shall be maximized to prevent short-
circuiting.
4
Berm
u.,* Suxal~
Dead Stuast"
lmK8tRCJ~. ~
"
100 Year Hi. 'Rat<< lewl
"Bench areas promotflgrowth of emergent vegetation.
. ~b:dl*~ distancot' ~t.~ the 011 tlet and at inlets to pt~vent short elrcuJtlDg of f'kwIs.
(2) The facility design shall provide adequate live storage to provide protection from the
design storm, consistent with lowest building elevation standards. Lowest building floor
elevation is defined as the lowest slab elevation for a home or building, including basements
and crawl spaces. The lowest building floor elevation for structures adjacent to wetlands and
water bodies shall be an elevation three feet above the 100-year high water level.
(3) Newly constructed or modified detention basins shall provide storage volume below the
outlet (dead storage) to allow for water quality treatment in accordance with the following,
whichever is most restrictive:
a. Water quality features meeting the MPCA NPDES construction permit for Permanent
Storm Water Management Systems;
b. Water quality treatment consistent with NURP criteria (90% removal of TSS and 60%
removal of TP for a standard NURP particle size distribution); and/or
c. For proposed projects in a watershed that directly discharges to a 'Preserve' water
feature (Table 20 of SWMP), NURP plus enhanced treatment is required as listed below:
1. Storm water ponds are required to include a sediment forebay at the inlet. The
volume of the sediment forebay should be 5 - 15% of the permanent pool sutface
area. The sediment forebay shall be a minimum of 3 feet plus the depth for sediment
storage.
2. Projects in watersheds that discharge directly to Assumption Creek must
incorporate BMPs as outlined in Appendix A C.1, C.2, C.3 and C.5 of the MPCA
N"PDES Construction General Permit, and as listed below:
1. DUling construction.
a. All exposed soil areas with a slope of 3: 1 or steeper, that have a continuous
positive slope to a special water must have temporary erosion protection or
permanent cover within 3 days after the area is no longer actively being
worked. All other slopes that have a continuous positi ve slope to a special
water must have temporary erosion protection or permanent cover within 7
days after the area is no longer actively being worked.
5
b. Temporary sediment basin requirements described in Part III.B.1-5 of the
NPDES Construction General Permit must be used for common drainage
locations that serve an area with five (5) or more acres disturbed at one time.
2. Post construction. The water quality volume that must be treated by the
project's permanent storm water management system described in Part III.C of
the NPDES Construction General Permit shall be one (1) inch of runoff from the
new impervious surfaces created by the project.
3. Buffer zone. An undisturbed buffer zone of not less than 100 linear feet from
the special water (not including tributaries) shall be maintained at all times.
Exceptions from this requirement for areas, such as water crossings or limited
water access, are allowed if the Pelmittee fully documents in the SWPPP the
circumstances and reasons that the buffer encroachment is necessary. All potential
water quality, scenic and other environmental impacts of these exceptions must be
minimized and documented in the SWPPP for the project.
4. Temperature Controls. The permanent storm water management system must
be designed such that the discharge from the project will minimize any increase in
the temperature of trout stream receiving waters resulting from the 1, and 2- year
24-hour precipitation events. This includes all tributaries of designated trout
streams within the section that the trout stream is located. Projects that discharge
to trout streams must minimize the impact using one or more of the following
measures, in order of preference:
a. Minimize new imperyious surfaces.
b. Minimize the discharge from connected impervious surfaces by discharging
to vegetated areas, or grass swales, and through the use of other non-structural
controls.
c. Infiltration or evapotranspiration of runoff in excess of pre-project
conditions (up to the 2-year 24-hour precipitation event).
d. If ponding is used, the design must include an appropriate combination of
measures such as shading, filtered bottom withdrawal, vegetated swale
discharges or constructed wetland treatment cells that will limit temperature
increases. The pond should be designed to draw down in 24 hours or less.
e. Other methods that will minimize any increase in the temperature of the
trout stream.
d. For proposed projects in a watershed that directly discharges to an 'Improve
l' (Table 20 of SWMP) water feature NURP plus enhanced treatment is
required as listed below:
1. Storm water ponds are required to include a sediment forebay at the
inlet. The volume of the sediment forebay should be 5 - 15% of the
permanent pool surface area. The sediment forebay shall be a minimum of
3 feet plus the depth for sediment storage.
2. Projects in watersheds that discharge directly to Riley or Bluff Creeks
must analyze the downstream system to ensure there is no increase in
runoff rates. One way to determine the downstream effects is to extend the
analysis downstream to a point where the proposed development
represents less than ten percent of the total watershed draining to that
point.
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(b) Skimmers and Outlets
1. Skimming devices should be designed to remove oils and floatable materials up to a one-
year frequency event. The skimmer should be set 12 inches below the normal surface water
elevation and should control the discharge velocity to 0.5 fps.
2. Outlets shall be evaluated for the need to dissipate energy so as to reduce velocities to
permissible levels as allowed by the soil and vegetation. At a minimum, flared end sections
should be provided with riprap consistent with MnlDOT standards. For areas with high flows
or where excessive erosion occurs or is anticipated, energy dissipation per Federal Highway
Administration standards shall be followed.
3. Riprap shall be provided below the channel grade and above the outfall or channel bottom
to insure that riprap will not be undermined by scour or rendered ineffective by displacement.
Riprap consisting of natural angular stone suitably graded by weight shall be designed for
anticipated velocities. Riprap shall be placed over a suitable filter material or filter fabric to
insure that soil particles do not move through the riprap and reduce its stability.
4. For outlets through berms or roadway embankments and all culverts under public traveled
streets, anti-seepage collars shall be used (see diagram in this section). The collars shall be
installed so as to increase the creep distance or seepage line along conduit by 15 percent. The
locations for the use of collars include:
a. All water and pond structures with a pool depth of two feet and two-day duration.
b. 250 acre watershed or more.
c. Design head of 10 feet or more.
Sec. 19-145. Erosion and sediment control.
(a) Erosion and Sediment Control Plans
1. An erosion and sediment control plan shall be created for any land disturbing activity.
Erosion and sediment control elements shall be implemented before any grading can begin. A
schedule of significant grading work will be required as part of the erosion and sediment
control plan.
2. The MPCA's most recent version of the NPDES Construction Storm Water Permit shall be
used to develop sediment and erosion control plans. Where the NPDES permit conflicts with
City standards, the more stringent standard will apply.
3. Site access roads (entrances to construction sites) shall be graded or otherwise protected
with silt fences, diversion channels or dikes and pipes to prevent sediment from exiting the
site via the access road. Primary site access roads shall be surfaced with crushed rock or
wood chips. The rock entrance shall extend for a minimum distance of 75 feet (150 for wood
chips) beginning at existing paved surface; additional length may be required as directed by
the City. All construction traffic shall utilize the entire length of the rock entrance.
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4. Soil tracked from the site by motor vehicles shall be cleaned from paved roadway surfaces
at least daily or as needed throughout the duration of construction. Roadway cleaning shall
be the responsibility of the party or palties having a permit with the City.
5. Streambank stabilization and stream bed control structures shall be designed based on the
unique site conditions present including soil conditions, flow rate, slope, and flow velocity.
6. Where inadequate natural vegetation exists or where it becomes necessary to remove
existing natural vegetation, both temporary vegetative and permanent vegetative cover shall
be addressed in the plans and specifications and be consistent with the provisions of the
NPDES Construction pelmit.
(b) Sediment Basins
I. Detention basins may be used as temporary sediment retention during the construction
phase. The design should include providing permanent storage volume for construction and
restoration phase sediment accumulation or the removal of the sediment to restore the
required permanent pool volume in the detention area.
2. Detention areas intended to permanently trap sediments shall provide excess dead storage
beyond the required water quality volume, to allow for sediment accumulation. Sediment
basins shall be capable of removing coarse suspended sediment from storm water for all
runoff events and the greatest practical grain size (#40 typically). Sediment storage volume
should be estimated by the universal soil loss equation and 0.5 tons per watershed acre per
year. Volume below the outlet can be estimated by using the runoff volume resulting from a
2.5" rainfall.
Sec. 19-146. Wetland elements.
(a) Water level fluctuations (peak elevation and duration) for wetlands shall be limited to two
feet and duration not to exceed 48 hours so as to prevent the destruction of wildlife habitat and
wetland vegetation.
(b) Sedimentation basins or sediment removal devices shall be provided prior to discharge into
wetlands.
(c) Variable bottom contours should be considered to provide deeper holes and flat shallow
benches. This feature will provide habitat for diversity of plants and wetland inhabitants for
wetland mitigation sites and storm water basins.
Section 4. The City Code, City of Chanhassen, Minnesota, is hereby amended by adding
sections to be numbered 19-200 through 19-208, which shall read as follows:
ARTICLE VII. SURFACE WATER MANAGEMENT
Sec. 19-200. Surface water management utility established.
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Surface water management shall be operated as a public utility pursuant to M.S. 9 444.075.
Sec. 19-201. Definitions.
The following words, terms, and phrases, when used in this article, shall have the meaning
ascribed to them in this section, except where the context clearly indicates a different meaning:
Surface water management budget is the annual budget approved by the city council for
surface water management including planning, monitoring, capital expenditures, personnel, and
equipment.
Surface water management fee means the quarterly charge for each parcel of nonexempt
property in the city for the management of surface water.
Utility factor means the ratio of runoff volume, in inches, for a particular land use, to the
runoff volume, in inches for a one-third-acre residential lot, assuming a two-inch rainfall and soil
conservation service (SCS) "type B" soil conditions.
Sec. 19-202. Surface water management fees.
The surface water management fees for tax parcels shall be calculated in accordance with section
4-50.
Sec. 19-203. Credits.
The city council may adopt policies for adjustment of the surface water management fees.
Information to justify a fee adjustment must be supplied by the property owner. Adjustment of
fees shall not be retroactive.
Sec. 19-204. Exemptions.
The following land uses are exempt from the surface water management fee:
(1) Public right-of-way.
(2) Lakes.
Sec. 19-205. Payment of fee.
Surface water management fees shall be involved quarterly. The amount due as shown on the
invoice shall be payable on or before the twentieth day of the month in which the invoice is
issued. A penalty of ten percent per quarter shall be added to all accounts that are not paid in full
by the due date. The penalty shall be computed on the unpaid balance not paid by the due date at
the time each quarterly statement is prepared. Any prepayment or overpayment of charges shall
be retained by the city and applied against subsequent fees.
Sec. 19-206. Appeal of fee.
If a property owner or person responsible for paying the surface water management fee believes
that a particular fee is incorrect, such person may file a written appeal with the city clerk.
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Appeals will be heard by the city council. No adjustment will be made to the utility factor for
property classifications 1, 2, and 3.
Sec. 19-207. Certification of delinquent fees.
If a surface water management fee is not paid within three months after a billing is issued, the
city council may certify the amount due, together with penalties, to the county auditor to be
collected with other real estate taxes on the parcel.
Sec. 19-208. Surface water management fund.
A separate fund shall be maintained for surface water management fees and expenditures.
Section 5. This ordinance shall be effective immediately upon its passage and publication.
PASSED AND ADOPTED this _ day of _, 200_, by the City Council of the City
of Chanhassen, Minnesota
Todd Gerhardt, City Manager Thomas A. Furlong, Mayor
(Published in the Chanhassen Villager on )
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CITY OF CHANHASSEN
CARVER AND HENNEPIN COUNTIES, MINNESOTA
ORDINANCE NO.
AN ORDINANCE AMENDING CHAPTER 20
CHANHASSEN CITY CODE, ZONING
THE CITY COUNCIL OF THE CITY OF CHANHASSEN, MINNESOTA ORDAINS:
Section 1. Section 20-1060 (2) of the City Code, City of Chanhassen, Minnesota, is hereby
amended to read as follows:
Protect creek corridors, wetlands, and significant stands of mature trees through the use of
careful site design; protective easements; sensitive alignment and design of roadways and
utilities; incorporation of natural features; landscaping and massing of trees that enhance existing
natural features and views; and the practices delineated in the City's Surface Water Management
Plan.
Section 2. Section 20-1061 (2) of the City Code, City of Chanhassen, Minnesota, is hereby
amended to read as follows:
Preservation of the natural conditions found on each site to the greatest extent possible, through
minimized removal of trees and other vegetation and soil, minimized site grading, and
application of the practices found in the city's Surface Water Management Plan.
Section 3. Section 20-1072 (a) of the City Code, City of Chanhassen, Minnesota, is hereby
amended to read as follows:
Where natural or existing topographic patterns contribute to the beauty or utility of a
development, they shall be preserved to the greatest extent possible. Modification to topography
will be permitted where and to the extent that it contributes to good design. All topographic
modifications shall adhere to the practices delineated in the city's Surface Water Management
Plan.
Section 4. Section 20-1085 (3) of the City Code, City of Chanhassen, Minnesota, is hereby
amended to read as follows:
Protect creek corridors, wetlands, and significant stands of mature trees through the use of
careful site design; protective easements; sensitive alignment and design of roadways/access and
utilities; incorporation of natural features; landscaping and massing of trees that enhance existing
natural features and views; and the practices delineated in the city's Surface Water Management
Plan.
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Section 5. The City Code, City of Chanhassen, Minnesota, is hereby amended by adding a
section to be numbered 20-1408, which shall read as follows:
Sec. 20-1408. Impervious surfaces.
Creation of impervious surfaces within the bluff setback may contribute to bluff instability due to
increased runoff and/or erosion. Impervious surfaces are prohibited within the bluff setback
unless specifically authorized within this article.
Section 6. Section 20-1551 (a) of the City Code, City of Chanhassen, Minnesota, is hereby
amended to read as follows:
Protect the Bluff Creek Corridor, wetlands, bluffs, and significant stands of mature trees through
the use of careful site design, protective covenants, sensitive alignment and design of roadways
and utilities, incorporation of natural features, landscaping, techniques outlined in the city's
surface water management plan, and the practices delineated in the city's Surface Water
Management Plan.
Section 7. Section 20-1552 (b) of the City Code, City of Chanhassen, Minnesota, is hereby
amended to read as follows:
Preservation of the natural conditions found in the primary zone and to the greatest extent
possible, preserving significant resources and minimizing impacts in the secondary zone through
cluster development and other practices which minimize the removal of vegetation, minimize
site grading, and application of practices found in the city's Surface Water Management Plan.
Section 8. Section 20-1556 of the City Code, City of Chanhassen, Minnesota, is hereby
amended to read as follows:
To the greatest extent possible, all development shall minimize the amount of impervious surface
by clustering development, using common access drives and utility corridors and minimizing
building footprint size. Roads, walkways, bike trails, and parking areas must be designed parallel
to natural contours with consideration to maintaining consolidated areas of natural topography
and vegetation. Management of surface run-off caused by impervious cover shall be designed
using practices delineated in the city's Surface Water Management Plan.
Within the secondary zone of the BCO District, areas with average slopes exceeding 25 percent
shall be preserved in their natural state and maintained as permanent open space. Areas with
average slopes less than 25 percent but greater than ten percent shall not exceed an impervious
surface coverage of 25 percent. Impervious coverage for areas where average slopes are less than
ten percent shall be governed by the underlying zoning district.
Section 9. Section 20-1561 (b) of the City Code, City of Chanhassen, Minnesota, is hereby
amended to read as follows:
Where possible, any disturbances of natural habitat areas within the secondary zone shall be
avoided. Any alterations to the natural habitat within the secondary zone shall adhere to the
practices delineated in the city's Surface Water Management Plan.
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Section 10. This ordinance shall be effective immediately upon its passage and publication.
PASSED AND ADOPTED this _ day of _,200_, by the City Council of the City
of Chanhassen, Minnesota
Todd Gerhardt, City Manager Thomas A. Furlong, Mayor
(Published in the Chanhassen Villager on )
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