Letter from Carver Soil & Water Conservation District 2-15-05
CARVER.
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219 East Frontage Road
Waconia, MN 55387
Phone: 952-442-5101
Fax: 952-442-5497
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http://www.co.carver.mn.us/SWCDlSWCD main.html
Mission Statement: To provide leadership in conservation and teach stewardship of the soil, water, and related
resources throuRh a balanced, cooperative prORram that protects, restores, and improves those resources.
February 15,2005
Robert Generous, Senior Planner
City of Chanhassen
7700 Market Boulevard
Chanhassen, MN 55317
Re: Hidden Creek Meadows
Mr. Generous:
The SWCD has taken the opportunity to review the 21-lot subdivision Hidden Creek Meadows.
The plan reviewed is dated 08/20/04 with revisions on 1/28/05. Please review and consider the
following comments and suggestions regarding some options for creek protection, erosion
control and sediment controls.
Creek Protection
Option 1: A phasing plan for the creek crossing is highly recommended. If it is plausible, the
culvert and crossing should be constructed from the existing Pipewood Lane side. It appears on
the plan the existing creek bed is north of the proposed culvert. Erosion and sediment controls
should be installed temporarily during construction to protect the creek. Once the culvert is in
and erosion controls applied, the creek could be diverted through the culvert and work could
continue to the north. If site access is needed during this creek crossing phase it is recommended
to gain access from the existing access driveways from north if possible.
Option 2: A temporary creek diversion with temporary erosion blanket (MN DOT category 4 or
5) or a temporary pipe could be constructed to divert the creek to the north or south of the
proposed crossing. While the creek is temporarily diverted, the crossing could be constructed
and stabilized prior to rerouting the stream through the permanent culvert.
Temporary rock fords should not be used; and crossing the stream with flowing water and no
established stable crossing must be avoided. Additionally, no work should take place in the
creek between the dates of March 15th to June 15th to minimize sediment impacts to spawning
fish species.
Erosion Control
1. MN DOT category 3 erosion blanket and seed should be applied to exposed creek slopes near
/ around Pipewood Lane within 24 hours of final grade.
2. Riprap, appropriately sized, should be installed at flared end outlets for energy dissipation
with underlying gravel base or geotextile fabric.
AN EQUAL OPPORTUNITY EMPLOYER
Sediment Control
1. Following stormwater inlet installation Wimco-type (or equal) inlet sediment controls should
be installed and regularly maintained.
2. Following street and utility installation, Chanhassen-specification Type-l silt fence or other
approved perimeter sediment control is needed for all positive slopes curbside.
3. The proposed temporary rock exit pad mayor may not be functional depending on the
phasing or temporary creek crossing practice chosen. If an alternative site access is allowed, a
temporary rock exit pad will be needed in that location as well. The rock exit pad is a high-
maintenance control. Multiple applications of rock will likely be needed. Geotextile fabric
installed under the rock helps promote the controls effectiveness and lifespan.
4. Alterations I deletions to the proposed silt fence are needed in the following areas:
- The silt fence proposed north of Block One does not appear to be needed for sediment
control as it is on top of a hill.
- The silt fence proposed across the existing and proposed Pipewood Lane is not practical
due to site access needs.
- Silt fence must not be used through the creek I concentrated flow areas of the site. The
silt fence should wrap up and around the culvert flared ends adjacent to Pipewood
Lane.
If there are any questions or if I can be of further assistance please contact the SWCD office.
Sincerely,
Aaron Mlynek
Aaron Mlynek, CPESC
Urban Conservation Technician
c. Lori Haak, City of Chanhassen (email)