Engineering Comments 7-11-05
CITY OF
CHANHASSEN
7700 Market Boulevard
PO Box 147
Chanhassen, MN 55317
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MEMORANDUM
TO:
Bob Generous, Senior Plannerq.
Mak Sweidan, Engineer .
()N'J\
July 11,2005
FROM:
DATE:
SUBJ:
Preliminary Plat Review for Chanhassen West Business Park
Addition - LUR No. 05-07
Upon review of the plans dated June 17,2005, prepared by Schoell & Madson,
Inc., I offer the following comments:
GRADING, DRAINAGE & EROSION CONTROL
The existing site is about 44.75 acres in size with scattered wetlands. In addition,
there are three existing buildings on the property which will have to be razed prior
to any grading operations. The current plans show buildings with proposed floor
elevations from 961-966. The applicant is now proposing to grade about 83% of
the site for the new building pads, storm pond and a proposed street ending with a
cul-de-sac. The current plans propose eight lots located along the proposed street
and cul-de-sac.
There are a few areas of concern with the grading plan. Staff would like to see
the applicant do a better job of matching in with the existing topography of the
site and maintain a side slope of 3:1 maximum. The existing site drains toward
the existing three wetlands on the northwesterly, southwesterly comers and east
side of the parcel. At these elevations, storm water from the buildings and parking
lots will drain toward the proposed catch basins and be conveyed via storm sewer
system to the proposed storm pond on the southwesterly comer of the parcel. The
pond will treat the water before discharging it to the adjacent wetland.
All of the ponds are required to be designed to National Urban Runoff Program
(NURP) standards with maximum 3: 1 slopes and a 10: 1 bench at the NWL. The
applicant is required to meet the existing site runoff rates for the lO-year and 100-
year, 24-hour storm events. Storm sewer sizing calculations must be submitted at
the time of final plat application. The storm sewer must be sized for a lO-year,
24-hour storm event. Drainage and utility easements must be dedicated on the
final plat over the public storm drainage system including ponds, drainage swales,
and wetlands up to the 100-year flood level. The interior lot storm sewer will
require private easements to be dedicated where the sewer crosses from one lot to
another.
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.
Bob Generous
July 11,2005
Page 2
The applicant must be aware that a retaining wall structure is not allowed within
the public street right-of-way. Also, any retaining wall exceeding four feet in
height must be designed by a registered structural engineer, with approved safety
fence and a building permit must be obtained.
Erosion control measures and site restoration must be developed in accordance
with the City's Best Management Practice Handbook (BMPH). Staff
recommends that the City's Type II erosion control fence, which is a heavy duty
silt fence, be used for the area adjacent to the existing wetlands on the north and
south grading limits of the site. Type I silt fence shall be used in all other areas.
A minimum 75-foot long rock construction entrance must be shown at the
entrance drive that will be utilized during construction. In addition, tree
preservation fencing must be installed at the limits of tree removal. Erosion
control blankets are recommended for all of the steep 3: 1 slopes with an elevation
change of eight feet or more.
All disturbed areas, as a result of construction, must be seeded and mulched or
sodded immediately after grading to minimize erosion. The applicant should be
aware that any off-site grading will require an easement from the appropriate
property owner. If importing or exporting material for development of the site is
necessary, the applicant will be required to supply the City with detailed haul
routes. A minimum 75-foot rock construction entrance must be added to the plans
at the proposed access off of Galpin Boulevard.
UTILITIES
Municipal sewer and water stubs are available to the site from Galpin Boulevard
on the east side of the parcel. The applicant is proposing to connect to the
existing utility stubs and extend them to the proposed lots to service the site. The
sanitary and watermain lines that run within the public street right-of-way and
within the shared driveway between Lots 4 and 5 until the last sanitary manhole
will be considered a public utility line and the remaining will be considered
private utility. Additional gate valves are needed for the shared private watermain
between any two lots. Minimum 20-foot wide easements will be required over
the public portion of the storm sewer lines between Lots 2 and 3.
The underlying property has been previously assessed for sewer, water and street
improvements and there is no remaining assessment due payable to the City.
Since the developer will be responsible for extending lateral sewer and water
service to the lots, the sanitary sewer and water connection charges will be
waived. The sanitary sewer and water hookup charges will be applicable for each
of the new lots. The 2005 trunk hookup charge is $1,458 for sanitary sewer and
$2,955 for watermain. Sanitary sewer and watermain hookup fees may be
specially assessed against the parcel at the time of building permit issuance.
Bob Generous
July 11,2005
Page 3
All of the utility improvements are required to be constructed in accordance with
the City's latest edition of Standard Specifications and Detail Plates. Upon
completion of the utility improvements, the utilities will be turned over to the City
for maintenance and ownership. The applicant is also required to enter into a
development contract with the City and supply the necessary financial security in
the form of a letter of credit or cash escrow to guarantee installation of the
improvements and the conditions of final plat approval. Permits from the
appropriate regulatory agencies will have to be obtained, including but not limited
to the MPCA, Department of Health, Watershed District, Carver County,
MnDOT, etc.
STREETS
The proposed development lies west of Galpin Boulevard (CSAH 19) and north
of Lyman Boulevard (CSAH 18), A-Minor Expander Arterials as identified on (
SRF Consulting Group Incorporated's Functional Classification Map. Proposedi
access to the site will be from Galpin Boulevard, which aligns with Stone Creek I
Drive, an existing local street extending east of Galpin Boulevard. \
Staff has researched the feasibility to move the proposed site access from Galpin '. \
Boulevard to Lyman Boulevard in response to citizens' requests. Due to wetland \
conditions, any access from the site to Lyman Boulevard would be 1,000 feet J
west of Galpin Boulevard. Carver County has identified Lyman Boulevard as a \
regional east-west collector with limited access; therefore Staff recommends that l
the access to Chanhassen West Business Park remain at the Galpin '\
Boulevard/Stone Creek Drive intersection. This recommendation is also .
consistent with Section 18-57 of the City Code, which states that "access to ,
arterial streets shall be at intervals of not less than one-fourth mile [1,320 feet] \1
and through existing and established crossroads".
SRF Consulting Group, Inc. analyzed the 2020 transportation system in
conjunction with the City's 2020 Comprehensive Plan. SRF's forecasted 2020
traffic volume for Galpin Boulevard was based on the 2020 Land Use Map and
the construction of the new Trunk Highway 212. The proposed land use of the
Chanhassen West Business Park is consistent with the 2020 land use used in
SRF's traffic analysis. SRF's report does not identify a need to upgrade Galpin
Boulevard by the year 2020.
Right turn lanes for north and southbound traffic exist at the Galpin Boulevard
intersection with Stone Creek Road and the proposed site access. The developer
must submit an access permit to Carver County Public Works for the proposed
connection to Galpin Boulevard. As stipulated by the Assistant County Engineer,
the developer must submit information on proposed turn lanes with the permit
application.
Bob Generous
July 11,2005
Page 4
There is one public street proposed with the project. The street is proposed as a
cul-de-sac running west of Galpin Boulevard and a private shared driveway
between Lots 4 and 5. The applicant is proposing the paved streets to be 32-feet
wide with a 60-foot wide right-of-way and a 46-foot cul-de-sac paved radius.
The applicant must be aware that the City's standard commercial street pavement
width is 36-foot wide from back-of-curb to back-of-curb and the cul-de-sac must.
be 48-foot in radius. Staff is fine with the 24-foot wide shared driveway between;'
Lots 4 and 5. The developer will be required to submit inspection/soil reports i
certifying that the private streets were built to a 7-ton design. i
Staff has concerns of movements of truck traffic accessing off Galpin Boulevard
to Lots 1 and 8 being too close. Staff recommends increasing the access width to
44 feet to create a three lane access off Galpin Boulevard and increase the turning
curb radius. Also, relocate Lots 1 and 8 easterly accesses further to the west and
re-align them opposite of each other.
The applicant should be aware that, in commercial districts, six-foot wide \
sidewalks are required and the parking driveway aisle must be 26-foot wide.
Cross-access easements will be obtained for the shared driveways and recorded
\
against the lots.
RECOMMENDED CONDITIONS OF APPROVAL
1. Prior to final platting, storm sewer design data will need to be submitted
for staff review. Depending on the size of the drainage area, additional
catch basins may be required at that time. The storm sewer will have to be
designed for a lO-year, 24-hour storm event. Drainage and utility
easements will need to be dedicated on the final plat over the public storm
drainage system including ponds, drainage swales, emergency overflows,
access routes for maintenance, and wetlands up to the 100-year flood
level. The minimum easement width shall be 20 feet wide.
2. The interior lot storm sewer will require private easements to be dedicated
where the sewer crosses from one lot to another.
3. Private utility easements are required for the sanitary sewer and water
lines that serve Lot 4 but go through Lot 5.
4. The sanitary sewer and water hookup charges will be applicable for each
of the new lots. The 2005 trunk hookup charge is $1,458 for sanitary
sewer and $2,955 for watermain. Sanitary sewer and watermain hookup
fees may be specially assessed against the parcel at the time of building
permit issuance.
5. On the site plan:
a. Revise the cul-de-sac pavement radius to 48 feet.
Bob Generous
July 11,2005
Page 5
b. Revise the parking driveway aisle from 24 feet to 26 feet wide.
c. Revise the public street width from 32 feet to 36 feet wide.
d. Increase the full access width off Galpin Boulevard to 44 feet and
create three lane access.
e. Shift Lots 1 and 8 easterly access further toward the west and
realign the across each other.
f. Show at least one, 6-foot wide, side walk along the public street.
g. Show the access off Galpin Boulevard turning curb radius.
h. Realign lot 5 access perpendicular to the shared driveway.
I. Show street lights.
J. Show handicap parks and ramps.
6. On the grading plan:
a. Extend silt fence type between the storm pond and Outlot A. Silt
fence Type II must be used adjacent to wetlands and storm pond.
b. Revise contour lines to match 3: 1 maximum slope and tie the
proposed contour lines with the existing contours for Lots 4,5,
south of Lot 2 and northeast of Lot 1.
c. Show the proposed contour lines for Lot 6.
d. Show all retaining walls top and bottom elevations.
e. Show all emergency overflows (EOF). The EOF must be 1.5'
lower than the adjacent lowest floor.
f. Revise Lot 6 parking slope to 0.7% minimum.
g. Add a note to remove any existing structure and access off Galpin
Boulevard and all disturbed areas, as a result of construction, must
be seeded and mulched or sodded immediately after grading to
minimize erosion.
h. Show 75-foot minimum construction rock entrance.
I. No retaining walls structure is allowed within public street and/or
public utility easements, revise accordingly.
J. Show 20-foot utility easement for the storm sewer between Lots 2
and 3
7. On the utility plans:
a. Show all existing and proposed drainage and utility easements.
b. Show the proposed sanitary and storm sewer stubs inverts.
c. Add storm sewer schedule.
d. Public storm sewer pipe type must be RCP and IS-inch minimum
diameter.
e. The last street accessible storm manhole (STMH#2) must be built
with a sump.
f. Revise sanitary sewer pipe from DIP to PVC-C900.
g. On the utility profile show all sewer and pipe crossings.
h. Minimum vertical separation must be 18 inches between
watermain and sewer.
1. Call out watermain fittings
Bob Generous
July 11,2005
Page 6
8. Any retaining wall over four feet in height must be designed by a
registered Civil Engineer in the state of Minnesota with an approved safety
fence on top of it. Also, it will require a building permit from the Building
Department.
9. Add the following City of Chanhassen Detail Plate Nos. 1002,2109,2110
2204,3104,3109,5201,5205,5214 and 5215.
10. Prior to final plat approval, a professional civil engineer registered in the
state of Minnesota must sign all plans.
11. All of the ponds are required to be designed to National Urban Runoff
Program (NURP) standards with maximum 3:1 slopes and a 10:1 bench at
the NWL.
12. Cross-access easements for the shared driveway accesses must be obtained
and recorded against the lots.
13. Any off-site grading will require easements from the appropriate property
owner.
14. Public utility improvements will be required to be constructed in
accordance with the City's latest edition of Standard Specifications and
Detail Plates. Detailed construction plans and specifications will be
required at the time of final platting. The applicant will also be required
to enter into a development contract with the City and supply the
necessary financial security in the form of a letter of credit or cash escrow
to guarantee installation of the improvements and the conditions of final
plat approval. The applicant must be aware that all public utility
improvements will require a preconstruction meeting before building
permit issuance. Permits from the appropriate regulatory agencies must
be obtained, including but not limited to the MPCA, Department of
Health, Watershed District, Carver County, MnDOT, etc.
15. Cross-access easements will need to be obtained and recorded against the
lots for each of the entrance drives.
16. If importing or exporting material for development of the site is necessary,
the applicant will be required to supply the City with detailed haul routes
and traffic control plans. The applicant should be aware that any off-site
grading will require an easement from the appropriate property owner.
17. All private streets are required to have 24- foot wide paved streets from
back-of-curb to back-of-curb, be built to a 7-ton design and contained
within a 40-foot wide private easement. At the completion of the project,
Bob Generous
July 11,2005
Page 7
the developer will be required to submit inspection/soil reports certifying
that the private streets were built to a 7-ton design.
18. All plans must be signed by a registered engineer in the state of
Minnesota.
19. All of the proposed house pads must have a rear yard elevation at least
three feet above the HWL of the adjacent ponds.
20. Installation of the private utilities for the site will require permits and
inspections through the City's Building Department.
21. Comply with the June 28, 2005Carver County memo and revise the plans
accordingly.
23. Revise plan sheet size to 24 x 36 using scale 50.
c: Paul Oehme, Public Works Director/City Engineer
Alyson Morris, Assistant City Engineer
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