7. SWMP WQ Fees Code Amend.
CITY OF
CHANHASSEN
7700 Market Boulevard
POBox147
Chanhassen, MN 55317
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WI'A'I. ci .chanhassen. mn. us
1
MEMORANDUM
To:
Todd Gerhardt, City Manager
From:
Lori Haak, Water Resources Coordinator.~ ~
Don Asleson, Environmental Resources Intern iV
()~~
January 3,2005 <
Date:
Re:
Amendment of City Code to Provide Water Quality Credit toward
Surface Water Management Charges
ACTION REQUESTED
City staff recommends the City Council adopt the attached ordinance to
amend the current surface water management connection charge ordinance
(City Code Section 18-63). This amendment is intended to provide credit to
developers who provide on-site storm water quality treatment. The 1994
Surface Water Management Plan (SWMP) and a memo associated with the
1994 SWMP suggest that this was the original intent; however, this is not how
the ordinance reads.
VOTE
Adopting the amendment requires a simple majority vote of City Council
members present.
CURRENT CODE
City Code Section 18-63 reads as follows:
(a) All subdivisions shall comply with the city's surface water
management plan dated February 1994, which is incorporated herein by
this reference.
(b) 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 subdivision will be given a credit
for any on site stormwater improvement which has been oversized to serve
The City 01 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.
.
Water Quality Credit Amendment
January 3,2005
Page 2 of 5
property outside the subdivision. 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 (1/2) acre lot. An additional charge will then be imposed if the
lot is fUl1her 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.
(c) Within the Bluff Creek Overlay (BCO) District, meet the additional purpose,
intent and standards of the BCO District.
ISSUE
The portion of the City Code that is under evaluation is: "The subdivision will be given a
credit for any on site storm water improvement that has been oversized to serve property
outside the subdivision."
Presently, oversizing ponds for treatment of storm water from off-site is the only way to
receive credit against storm water quality charges. This is not equitable because
developers who provide treatment for their subdivision's storm water both give up
developable land and pay the entire water quality charge. Developers who do not provide
water quality treatment for their storm water pay only the charge. Additionally, it
appears that the initial intent of the SWMP funding mechanism was to provide credit for
on-site water quality improvements that provide treatment for on-site storm water, off-
site storm water or both.
ANALYSIS
Current Practices
CUlTently, the City requires most developments to provide on-site treatment for storm
water in accordance with National Urban Runoff Program (NURP) standards and pay the
full storm water quality connection charges based on the property's zoning and area of
development. The charges assessed to a developer assume that all of the storm water is
leaving the development site and that the City must create treatment infrastructure to
accommodate this additional storm water. Small subdivisions or developments are
typically exempt from providing ponding on-site since regional storm water ponds
provide far more effective treatment and fewer maintenance requirements.
The CUlTent practice of charging for connection to storm water infrastructure offers little
compensation for developers provide water quality treatment for storm water on their
Water Quality Credit Amendment
January 3, 2005
Page 3 of 5
sites. This practice is not equitable for developers who provide storm water treatment
because they provide the property for the ponds, construct the ponds and pay the full
storm water connection charges.
Pond Efficiency
According to the City's Best Management Practice Handbook, the construction of NURP
ponds with a hydraulic residence time of 16 days yields phosphorous removal efficiency
values ranging between 47 to 68 percent. Staff researched in attempt to find a more
precise range of phosphorous removal efficiencies for the Twin Cities metropolitan area.
However, very little information confirming the NURP values exists. Natural differences
in pond conditions (location, soils, vegetation, sizing) and inflow can cause variation in
pond efficiencies. In addition, management practices and maintenance schedules can
have a marked effect on pond effectiveness.
PROPOSED REVISION
Staff recommends that an ordinance amendment be adopted to change the mechanism for
calculating storm water quality connection charges. The ordinance amendment would
provide developers with a 50% reduction of storm water connection charges when City-
approved NURP storm water ponds are constructed to accommodate and treat on-site
storm water. The 50% reduction in the water quality connection charge is based on an
estimated water quality benefit obtained through NURP ponding. The City would retain
the additional 50% of the storm water quality connection charge to fund future projects
that would remove the remaining 50% of the development's phosphorous.
Additionally, staff recommends that if the developer oversizes the ponding within a
development to accommodate the surface water treatment from an off-site development
that does not include such infrastructure, a 50% credit per acre treated from off-site
would be given.
Staff realizes that 50% will not be exactly the amount of phosphorous being removed
from the ponds. However, it provides a solid starting point for the City of Chanhassen in
balancing the scales for developers who provide on-site storm water treatment. As the
Surface Water Management Plan is updated later in 2005, this fee structure will be
evaluated further.
The proposed ordinance revision would not affect the calculation of water quantity fees.
EXAMPLES
To illustrate the impact of the proposed ordinance on development within Chanhassen,
the Surface Water Management water quality connection charges for the Pinehurst and
Crestview Drive subdivisions are shown below. The table shows the water quality
Water Quality Credit Amendment
January 3,2005
Page 4 of 5
charges, water quality credits and totals under both the current ordinance and the
proposed ordinance.
Current Proposed
Ordinance Ordinance
Pinehurst (23.26 acres)
Water Quality Charge $ 25,532 $ 25,532
Water Quality Credit $ 6,449 $ 15,127
Total $ 19,084 $ 10,405
Crestview (3.36 acres)
Water Quality Charge $ 3,672 $ 3,672
Water Quality Credit $ $
Total $ 3,672 $ 3,672
"These figures do not include water quantity charges.
As evidenced in the table, under the current ordinance the Pinehurst subdivision would
only receive credit for the ponding provided from off-site. Under the proposed
ordinance, Pinehurst would receive credit for ponding provided for their subdivision and
the Crestview Drive subdivision. In both scenarios, the Crestview Drive subdivision
receives no credit because no storm water ponding is provided.
RECOMMENDA TION FOR CODE REVISION
City Code Section 18-63 shall be amended to read as follows:
(a) All subdivisions shall comply with the city's surface water management plan dated
February 1994, which is incorporated herein by this reference.
(b) 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 subdivision
will be given a credit for any on::site storm_water Quality improvement~ wffiefl that
has been are desi2ned to treat runoff from the subdivision to NURP standards.
The credit will be calculated usin2 the followin2 formula: The per acre water
Quality connection char2e will be multiplied by the on-site draina2e area for
water Quality treatment facilities. This value will then be multiplied by 50%.
The subdivision will also be 2iven a credit for on-site storm water Quality
improvements that are oversized to sef¥e treat runoff from property outside the
subdivision to NURP standards. The credit will be calculated usin2 the followin2
formula: The per acre water Quality connection char2e will be multiplied by the
off-site draina2e area for water Quality treatment facilities. This value will then
be multiplied by 50 %. Credit will not be 2ranted if the storm water from
contributin2 off-site areas is already treated to NURP standards. The water
Water Quality Credit Amendment
January 3, 2005
Page 5 of 5
Quality connection char2es that correspond to the land uses that contribute to
the storm water 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 (1/2) 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.
(c) Within the Bluff Creek Overlay (BCO) District, meet the additional purpose,
intent and standards of the BCO District.
A TT ACHMENTS
1) Recommended Ordinance for Section 18-63 of the Chanhassen City Code
2) Chanhassen City Code Section 18-63, Surface water management.
3) Excerpt from 1994 Surface Water Management Plan, Section VI-D, Dedication
Requirements.
CITY OF CHANHASSEN
CARVER AND HENNEPIN COUNTIES, MINNESOTA
ORDINANCE NO.
AN ORDINANCE AMENDING SECTION 18-63 OF CHANHASSEN CITY CODE,
SURFACE WATER MANAGEMENT
THE CITY COUNCIL OF THE CITY OF CHANHAS~EN, MINNESOTA ORDAINS:
Section 1. Section 18-63 of the City Code, City of Chanhassen, Minnesota, is hereby
amended to read as follows:
(a) All subdivisions shall comply with the city's surface water management plan dated
February 1994, which is incorporated herein by this reference.
(b) 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 subdivision
will be given a credit for on-site storm water 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%. 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 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%. Credit will not be granted if the storm water
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
storm water 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 (112) 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.
(c) Within the Bluff Creek Overlay (BCO) District, meet the additional purpose,
intent and standards of the BCO District.
Section 2. This ordinance shall be effective immediately upon its passage and
publication.
PASSED AND ADOPTED this day of
City Council of the City of Chanhassen, Minnesota
, 2005, by the
Todd Gerhardt, City Manager Thomas A. Furlong, Mayor
(Published in the Chanhassen Villager on )
ARTICLE III. DESIGN STANDARDS
J:'age 14 or 14
(Ord. No. 33-0, § 6.6, 2-25-85; Ord. No. 153, § 2, 11-4-91; Ord. No. 204, §§ 1, 2, 5-9-94; Ord.
No. 240, § 7,7-24-95; Ord. No. 250, § 1,4-8-96; Ord. No. 255, § 1,7-22-96; Ord. No. 324, § 19,
7-9-01 )
Cross references: Landscaping and tree removal, § 20-1176 et seq.
Sec. 18-62. Erosion and sediment control.
(a) The development shall conform to the topography and soils to create the least
potential for soil erosion. Four (4) inches of topsoil shall be replaced on all disturbed
areas.
(b) The smallest practical increment of land shall be exposed at anyone (1) time
during development.
(c) Detailed requirements for each plat shall be set forth in the development
agreement.
(d) Subdivision development shall conform to the city's Construction Site Erosion and
Sediment Control Best Management Practices Handbook, as amended.
(Ord. No. 33-0, § 6.7, 2-25-85; Ord. No. 178, § 1, 10-26-92; Ord. No. 318, § 1, 4-23-01)
Sec. 18-63. Surface water management.
(a) All subdivisions shall comply with the city's surface water management plan dated
February 1994, which is incorporated herein by this reference.
(b) 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 subdivision will be given a
credit for any on site stormwater improvement which has been oversized to serve
property outside the subdivision. 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 ( 1/2) 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.
(c) Within the Bluff Creek Overlay (BCO) District, meet the additional purpose, intent
and standards of the BCO District.
(Ord. No. 33-0, § 6.8, 2-25-85; Ord. No. 225, § 1, 10-24-94; Ord. No. 286, § 2, 12-14-98; Ord.
No. 324, § 20, 7-9-01)
Secs. 18-64--18-75. Reserved.
http://library12.municode.coml gateway .dl1/MN/minnesota/7 83/854/857?f=templates$fn=... 12/15/2004
VI-D Dedication Requirements
In accordance with Minnesota Statute 462.358, all new developments may be requITed to
dedicate land and construct a pennanent detention facility for the purpose of treating
increased pollutants in the runoff as proposed in the SWMP. The size of the proposed
treatment facilities and their removal efficiency will depend on the required degrée of
protection for the down stream wetlands and waterbodies.
An agreement to construct the required treatment basins or ponding areas and the
declaration of such property or easements shall be executed concurrent with the site plan
or plat approval.
--
*
Because of the regional character of the water quality improvements proposed in this report,
it is possible that no water quality ponding is shown inside a given development. In this
case, the City will request a cash contribution from the developer to help the construction
of the downstream pond that eventually will treat the increased pollutants in the runoff from
the development. the methodology to calculate this cash dedication is explained in Section
-
VI-D.2.
VI-D. 1 Ponding and Land Dedication
Based on the regional water quality improvements proposed in this report, and the specific
circumstances of the development, the City mayor may not require ponding and land
dedication in the development. If based on the results of the SWMP, the City requires
dedication of land, or easement for ponds and treatment basins, the surface size of the
pond, and other pond dimensions should be calculated using the Walker design criteria.
The necessary pond area will determine the land to be dedicated for water quality ponding
by the developer.
Any decision made by the City concerning ponding in new developments will have to be
oriented towards keeping the desired level of protection in lakes and wetlands under. fully
developed conditions. Interim phosphorus loads into potential lakes and wetlands shall not
exceed, under any circumstances, ultimate conditions levels.
Requirements for New Developments
VI-9
VI-D.2 Cash Dedication
/~)
If on-site water quality treatment is not provided by the developer because it is not !easibJe
or it is not desired by the City, cash dedication may be required. Çash dedication may also
be required if the proposed water quality pond is not big enough to satisfy phosphorus
removal requirements.
The cash dedication, if utilized, win be equal to the cost of land and cost of building the wet
volume needed for phosphorus removal at the site. The requirement, for cashin lieu of
land and pond construction, shall be based upon a schedule in accordance with the
prescribed land use zoning. Values are calculated using the market values of land in the
City of Chanhassen, plus a value of $2.50 per cubic yard for excavation of the pond.
Land values for cash equivalent contributions will be consistent with the following rate
schedule:
1993 Rate Schedule For Cash Dedication *
Per Acre
Single Family
Duplex
Town Home
Schools, Churches
Apartment
Industrial
Commercial
* Rates to be updated annually by the City CounciJ.
$18,000
$21,000
$24,000
$23,000
$27,000
$43,560
$130,680
~-)
The cash dedication chart shown in Figure VI-Dl is intended to help estÎinate the
excavation cost and the land cost for typical types ofdeveIoþment. Figure VI-Dl shows
ranges for wet volume and pond area by using the curve number (CN) value and size of the
development. The CN value correlates to impervious areas as described in Soil
Conservation Services TR-20 Hydological Methodology. The chart is a graphical solution
to the Walker model and should be used only for estimation purposes, the final cost caIibe
obtained using the original model or by request to the City.
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VI-] 0
Requirements for New Developments
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The City may require cash even if it is determined by the City that there is additional
treatment capacity in an existing downstream treatment basin. To make it fair for all
developers in the City, no developer should be entitled to use an existing oversized
downstream treatment basin without contributing to the City's water quality fund.
-
VI-D.3 Mitigative Measures
In addition to the options of additional treatment basin construction, and cash dedication,
new developments may also be required to provide other mitigative measures if the
development results in an increase in the phosphorus export to downstream waterbodies
classified in the Chanhassen Stormwater Management Plan as lakes or "Pristine" or
IINatural1l wetlands.
Other mitigative measures may include but not be limited 10: reducing impervious area,
flow diversion, first flush treatment, or treatment of storm water discharge through other
means.
Requirements for New Developments
VI-I3