Memo from Alyson Fauske 11-21-06
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
MEMORANDUM
TO:
Bob Generous, Senior Planner
Alyson Fauske, Assistant City Engineer ~
FROM:
DATE:
November 21,2006
SUBJECT:
Review of Conditional Use Permit and Site Plan for Autobahn
Motorplex- Planning Case No. 06-34
GRADING AND DRAINAGE
The site topography is challenging due to the 40 foot drop in elevation from the existing
curb cut on Audubon to wetlands; the site also drops more than 20 feet from the railroad
to the wetland.
The grading plan shows that all of the proposed lots will be mass graded. Staff examined
the feasibility of extending a common drive between the buildings, eliminating the need
for the access along the eastern half of the southern-most driveway, however the
developer has indicated that the proposed buildings can not be designed to have a grade
drop within them.
The developer proposes to install storm sewer throughout the site to convey runoff to the
proposed pond. This storm sewer shall be privately owned and maintained since it will
not convey runoff from a public right of way. The proposed pond is designed to treat
runoff from the site according to NURP standards. The pond is designed to provide rate
control for the 2-, 10-, 100- and two (back to back) 100-year rainfall events.
The grading plan must be revised to show proposed pavement grades for the driveway
access to the northern office/warehouse. .
The grading plan must show proposed pavement grades. Pavement grades must not
exceed 10%. The private streets within the development must be constructed to a nine
ton design.
An additional spot elevation must be shown on the south end of the storage building
immediately west of the northern office/warehouse to ensure positive drainage. Note the
proposed rim and invert elevation of the storm sewer located at the driveway intersection
south of bore hole location #3.
RETAINING WALLS
Due to the site topography the developer proposes to construct retaining walls at the
following locations, as shown on Sheet SP:
The City of Chanhassen · A growing community with clean lakes, quality schools, a channing downtown, thriving businesses, winding trails, and beautiful parks. A glBat place to live, work, and play.
Location Length Maximum Height
(approximate) (approximate)
South of the pond 120 feet 8 feet
East of the pond 190 feet 14 feet
North of the clubhouse 200 feet 6 feet
North of the northern storage facilities (2 locations) 50 feet (each) 4 feet (both)
West of the northern office/industrial building, near the 170 feet 4 feet
northern property line
West of northern office/industrial building 500 feet 15 feet
Near entrance gate 80 feet 4 feet
Retaining walls four feet or higher require a building permit and must be designed by an Engineer
registered in the State of Minnesota.
STREETS AND SITE CIRCULATION
The developer proposes to access the site from the existing curb cut at Audubon Road. This access
location was approved with the Audubon Court final plat in 1989; this plat was never recorded. This
access is approximately 280 feet south of Park Road. The access spacing guideline for this segment of
Audubon Road is 660 feet. The applicant submitted a site plan where the access aligns with Park Road.
This alignment was not pursued since the height of the retaining wall west of the northern
office/warehouse building would be between 16 feet to 22 feet in order to accommodate this alignment.
A private street will extend west to the site, with a gate proposed west of the eyebrow located in the
southwest of the southern office/industrial building. The developer must provide a drainage and utility
easement over the pavement section that will be used to access the pond for maintenance purposes. The
developer must coordinate with City staff to ensure that pond maintenance and emergency vehicles will
be able to access the gated area.
The width of the drive aisle between southeast of the pond must be minimum 26 feet wide in addition to
the proposed parallel parking stalls. The remaining drive aisles within the development meet or exceed
the minimum standards.
UTILITIES
The developer proposes to loop privately owned and maintained eight inch watermain from the existing
trunk watermain on the west side of Audubon Road. If fire code permits, staff recommends that the
private watermain be six inch diameter for water quality purposes.
Due to the site topography, all buildings within the storage facility will be served by a privately owned
and maintained forcemain, which will connect to the proposed eight inch privately owned and maintained
sanitary sewer between the two office/warehouse buildings.
The City's construction observer shall be present for all sanitary sewer and watermain testing to ensure
that the proposed connections to the City facilities are in conformance with engineering standards. The
developer shall pay for the inspection bills and submit a $5,000.00 security to ensure payment of these
bills.
Bob Generous
November 21,2006
Page 3
RECOMMENDA TION
Engineering recommends approval of the Autobahn Motorplex Conditional Use Permit and Site Plan
subject to the following:
1. The grading plan must be revised to show proposed pavement grades for the driveway access to
the northern office/warehouse.
2. The grading plan must show proposed pavement grades.
3. Pavement grades must not exceed 10%.
4. The private streets within the development must be constructed to a nine ton design.
5. An additional spot elevation must be shown on the south end of the storage building immediately
west of the northern office/warehouse to ensure positive drainage.
6. Note the proposed rim and invert elevation of the storm sewer located at the driveway
intersection south of bore hole location #3.
7. The developer must provide a drainage and utility easement over the pavement section that will
be used to access the pond for maintenance purposes.
8. The developer must coordinate with City staff to ensure that pond maintenance and emergency
vehicles will be able to access the gated area.
9. The width of the drive aisle southeast of the pond must be minimum 26 feet wide in addition to
the proposed parallel parking stalls.
10. If fire code permits, staff recommends that the private watermain be six inch diameter for water
quality purposes.
11. The City's construction observer shall be present for all sanitary sewer and watermain testing to
ensure that the proposed connections to the City facilities are in conformance with engineering
standards.
12. The developer shall pay for the inspection bills and submit a $5,000.00 security to ensure
payment of these bills.
c: Paul Oehme, Public Works Director/City Engineer
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