Water ResourcesMEMORANDUM
TO: Sharmeen Al-Jaff, Senior Planner
FROM: Don Asleson, Natural Resource Technician
DATE: December 1, 2021
RE: Gateway North/Gateway Place
Upon review of plans prepared by Westwood dated January 6, 2006 I offer the following comments and recommendations:
GRADING, DRAINAGE AND EROSION CONTROL
Storm Water Management
Details on the storm sewer connections to proposed Lake Susan Drive and proposed TH 212 should be provided. An emergency overflow for the proposed pond should be illustrated. The applicant
should submit a routing plan for any pond overflows from the site to a public water body. The storm water pond should be platted in an outlot.
Easements
Drainage and utility easements (minimum 20 feet in width) should be provided over all storm water infrastructure, including any emergency overflow structures.
Erosion and Sediment Control
All exposed soil areas should have temporary erosion protection or permanent cover year round, according to the following table of slopes and time frames:
Type of Slope Time (Maximum time an area can
Steeper than 3:1 7 days remain open when the area
10:1 to 3:1 14 days is not actively being worked.)
Flatter than 10:1 21 days
These areas include constructed storm water management pond side slopes, and any exposed soil areas with a positive slope to a storm water conveyance system, such as a curb and gutter
system, storm sewer inlet, temporary or permanent drainage ditch or other natural or man made systems that discharge to a surface water.
The plans should be revised to show rock construction entrance installation per Chanhassen Detail Plate 5301.
Wimco or similar inlet protection should be installed at all inlets that may receive storm water from site per Chanhassen Detail Plate 5302A. All inlet protection must be inspected and
maintained to comply with NPDES requirements.
Street cleaning of soil tracked onto public streets should include daily street scraping and street sweeping as needed.
Surface Water Management Fees
All applicable water quantity and quality fees have been paid.
Other Agencies
The applicant should apply for and obtain permits from the appropriate regulatory agencies (e.g., Riley-Purgatory-Bluff Creek Watershed District, Minnesota Pollution Control Agency (NPDES
Phase II Construction Permit), Minnesota Department of Natural Resources (for dewatering)) and comply with their conditions of approval.
RECOMMENDED CONDITIONS OF APPROVAL
Details on the storm sewer connection to proposed Lake Susan Drive and proposed TH 212 should be provided. An emergency overflow for the proposed pond should be illustrated. The applicant
should submit a routing plan for any pond overflows from the site to a public water body.
Drainage and utility easements (minimum 20 feet in width) should be provided over all storm water infrastructure, including any emergency overflow structures. The storm water pond should
be platted in an outlot.
Erosion control blanket shall be installed on all slopes greater than or equal to 3:1. All exposed soil areas shall have temporary erosion protection or permanent cover year round,
according to the following table of slopes and time frames:
Type of Slope Time (Maximum time an area can remain open
Steeper than 3:1 7 days when the area is not actively being worked.)
10:1 to 3:1 14 days
Flatter than 10:1 21 days
These areas include constructed storm water management pond side slopes, and any exposed soil areas with a positive slope to a storm water conveyance system, such as a curb and gutter
system, storm sewer inlet, temporary or permanent drainage ditch or other natural or man made systems that discharge to a surface water.
Rock construction entrance shall be installed as illustrated on Chanhassen Detail Plate 5301.
Wimco or similar inlet protection shall be installed at all inlets that may receive storm water from site per Chanhassen Detail Plate 5302A. All inlet protection shall be inspected and
maintained to comply with NPDES requirements.
Street cleaning of soil tracked onto public streets shall include daily street scraping and street sweeping as needed.