1 WET TH 5650 City Center Drive, PO Box 147
Chanhassen, Minnesota 55317
Phone 612.93Z 1900
General Fax 612.93Z5739
Engineering Fax 612.93Z9152
Public SafeO, Fax' 612.934.2524
Web www. ci. chanhassen, mn. us
MEMORANDUM
TO:
FROM:
DATE:
SUB J:
Scott Botcher, City Manager
Kate Aanenson, Community Development Director
Phillip Elkin, Consultant HDR
March 30, 2000
Wetland Alteration Permit 99-1 - TH 5 ~ MnDOT
BACKGROUND
The Minnesota Department of Transportation has proposed a roadway
construction project on TH 5 extending approximately 2 miles from TH 41
to CSAH 17, in the City of Chanhassen. While this project has been in
design for many years, the final wetland impacts have just recently been
determined.
This project will impact eleven separate basins throughout the project, for
a total of 3.16 acres of wetland (see exhibit 1). Most of these wetlands are
small areas (less than 1 acre)along the roadside which are connected to
the highway ditch system. However, there are 1.38 acres of wetland
impacts to DNR protected waters 5, 6, 10 and 11.
MITIGATION
Mitigation of wetland impacts shall be at a 2:1 replacement ratio.
However, the DNR protected waters must be mitigated at a 4:1 ratio.
MnDOT along with the City of Chanhassen's Water Resources
Coordinator attempted to find replacement sites within the project
corridor. Five sites were investigated, and it was determined that only
one site would have the hydrologic soils to support a wetland
environment. This site however was not within the right-of-way and was
determined to be too costly to convert into wetlands. Therefore, with no
feasible on site mitigation, MnDOT has decide to exercise their right under
the State of Minnesota's Wetland Conservation Act, to use wetland credits
from their wetland bank to mitigate the wetland impacts from this
The ¢it~ o£Chanhassen. A cmwin¢ contmu,i~, with c/ea, lakes, aua//t~, schools, a cha~min¢ downtown, thrivinv businesses, and beautiful parks. A great v/ace to live, work, and play
Wetland Alteration Permit - TH 5/MnDOT
March 30, 2000
Page 2
project. Because this is a project by the State, MnDOT does not have to follow local
rules for wetland mitigation, only State rules. Whereas the City of Chanhassen's rules
do not allow the use of wetlands created outside of the City for wetland credits, WCA
allows replacement to occur in a much larger watershed.
The 5.52 acres of DNR wetland mitigation will be through a wetland project near
Mitchell Lake in Eden Prairie. Additional new wetland credits will be withdrawn from
wetland credits from a project at TH 101 and TH 13.
2.26 acres of public value credits will be given to the applicant with the construction of
stormwater ponds and buffers on this project. The remaining public value credits will
be withdrawn from various MnDOT wetland projects. An attached table outlines the
mitigation and replacement sites MnDOT will be using for this project.
The proposed water management of this site will meet all of the City's SWMP water
quality and water quantity goals.
RECOMMENDATION
Staff recommends the Planning Commission adopt the following motion:
"The Planning Commission recommends the City Council approve Wetland Alteration
Permit 99-1 subject to the following conditions:
1. Wetland Conservation Act and the City of Chanhassen Surface Water Management
Plan requirementsl
2. The applicant shall develop a sediment and erosion control plan in accordance with
the City's Best Management Practice Handbook. Type III erosion control fencing
will be required around the existing wetlands.
ATTACHMENTS
1. Location map
2. Wetland maps
3. Mitigation summary
\ \cfsl\vol2\eng\phillip\wetlands\mndotwap.doc
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SP 1002-61 T.H.5. CHANHASSEN, MN
WETLANDS
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SP 1002-61 T.H.5 CHANHASSEN, MN
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Figure 9
S.P. 1002-61, T.H. 5, CHANHASSEN, MINNESOTA
WETLAND SUMMARY TABLE
WCA Wetland Impacts =
DNR Wetland Impacts =
Total Wetlahd Impacts =
1.78 acres
1.38 acres
3.16 acres
Acres Impacted =
Replacement Ratio =
Total Mitigated Acres =
Acres Impacted =
Replacement Ratio =
Total Mitigated Acres =
DNR Wetland Mitigation
1.38 acres
4:1
5.52 acres
WCA Wetland Mitigation
1.78 acres
2:1
3.5'6 acres
WCA Wetland Mitigation Credit Distribution
Public Value Credits = 1.78 acres
New Wetland Credits = 1.78 acres
Total Mitigated Acres = 3.56 acres
On-Site WCA Mitigation
On-Site Water Quality Treatment Ponds = 2.26 acres
Credit Ratio = 75%
Public Value Credits (Produced) = 1.70 acres
Public Value Credits (Required) =
Public Value Credits (Produced) =
Public Value Credits (Withdrawal) =
1.78 acres
1.70 acres
0.08 acres
Type of Withdrawal
DNR Wetland Credit
New Wetland Credit
Public Value Credit
Withdrawal Summary
Acres Site
5.52 Mitchell Lake - TH 5, S.P. 1002-44
1.78 Rice Lake/Wilke Easement - TH 101 & TH 13
0.08 Wetland G - TH 3, S.P. 1928-35