HomeMy WebLinkAboutThe Royal Golf Club Residential Development EAW_WCD Comments-signed
Supervisors: Louise Smallidge ▫ Bob Rosenquist ▫ George Weyer ▫ John Rheinberger ▫ Jim Levitt
November 22, 2016
Stephen Wensman, Planning Director
City of Lake Elmo
3800 Laverne Ave N.
Lake Elmo, MN 55042
RE: The Royal Golf Club Residential Development EAW
Dear Steven,
The Washington Conservation District (WCD) has received and reviewed the above-mentioned EAW.
The WCD review focuses on wetlands, erosion and sediment control, natural area management, and
stormwater management. Based on this review the WCD offers the following comments:
Section 7 – Cover Types
Use of native vegetation and habitat restoration is encouraged in the open space areas, including native
vegetated buffers around stormwater treatment systems. Enhancing the greenway cooridor that
connects Lake Elmo to natural areas to the east is encouraged.
Section 10 – Geology, Soils and Topography / Land Forms
Section b. Soils and Topography
• Compliance with NPDES, watershed, and local requirements will minimize adverse impacts of soil
erosion and sedimentation. The WCD can provide support to the City to ensure compliance as
needed. The WCD recommends phasing the earthwork and grading to the greatest extent possible
to limit the scale and duration of exposed soils during construction.
• Preserve HSG B soils to the extent possible. Protecting zones of optimum infiltration from
compaction is preferred
• Minimize soil compaction and provide soil restoration in landscaped areas to enhance infiltration
• Deep-rip the soils with a toothed bucket in low or compacted areas to promote infiltration after
major construction is complete
Section 11 – Water Resources
Section iv. Surface Waters
• The EAW indicates the site will meet City and VBWD infiltration guidelines, which recommend
retaining the 1.1” rain event on-site. WCD encourages the use of bioretention to meet the onsite
volume retention standards. Bioretention promotes both infiltration and evapotranspiration which
more effectively mimics terrestrial hydrology than pure infiltration systems. These systems are
designed to be distributed throughout the site and treat small contributing drainage areas, breaking
up larger catchments into smaller, more manageable parts. Minimizing the drainage area provides
multiple benefits to stormwater treatment, including the potential for reduced infrastructure
conveyance costs.
To ensure the long-term effectiveness of volume control, the following design specifications are
presented for consideration:
• Do not rely on long-term infiltration from unlined stormwater ponds or wet detention basins
• Install bioretention/infiltration practices off-line
• Include flow-splitter and high-flow bypass
• Provide pre-treatment (especially for sediment to prolong the life of a practice)
• Keep the max water depth to acceptable levels based on soil types and actual infiltration rates
• Refer to the Minnesota Stormwater Manual, 2013 (on MN PCA website) for additional design and
implementation considerations
The WCD is also serving on the WCA TEP and will provide comments on the wetland permiting through
that process.
Section 13 – Fish, Wildlife, Plant Communities and Sensitive Ecological Resources (Rare Features)
Section d.
• Buckthorn removal from entire project area rather than leaving visual barrier along exterior
roadways will minimize spread of this restricted noxious weed. Replace visual barrier of
removed Buckthorn by replanting native trees and shrubs.
Conclusions
There are no known impacts that have not already been addressed in this EAW that warrant an
Environmental Impact Statement. The Washington Conservation District appreciates the opportunity to
review this EAW. Please call me at 651-330-8220, extension 20, if you have any questions about our
review.
Sincerely,
Jay Riggs, District Manager
Washington Conservation District
Cc: John Hanson, VBWD