PC Staff Report Attachment 4. Letter from Watershed dated May 26, 2017Al-Jaff, Sharmeen
From: Terry Jeffery <tjeffery@rpbcwd.org>
Sent: Friday, May 26, 2017 4:25 PM
To: Al-Jaff, Sharmeen; Fauske, Alyson
Cc: Smith, Stephanie
Subject: West Park
Attachments: 2017-038_West Park_Review Comments_2017May24.docx
Please find attached our preliminary comments on West Park. Feel free to call with questions. Have a fun and safe
weekend.
Kind regards,
Terry
Terry Jeffery, Project and Permit Manager
RILEY
18681 Lake Dr. EastPURGATORY
BLUFF CREEK Chanhassen, MN 55317
WATERSHED DISTRICT 952.807.6885
1
West Park Review Comments to Applicant
5/25/17 TRJ
The RPBCWD received your application and supporting information for the proposed West Lake
subdivision and site plan review in Chanhassen on May 19, 2017. The application has been
assigned permit number 2017-038. The application is considered complete. This does not
constitute an approval. A review of the submitted information has generated the following
questions or comments. Many of these items will need to be addressed before a
recommendation can be made to the RPBCWD Board of Managers.
General Comments
1. The Stormwater Management Hydrologic and Hydraulic Study includes both the
northerly and the southerly parcels. However, sheet 7 of 23 indicates that the southern
parcel is a future phase. There are no other detailed plans of the southern parcel
grading & drainage, utilities, storm sewer, etc.). If the applicant wishes the southern
parcel to be part of this application, additional information will be needed to process and
approve this portion of the application. Please note, if it is the applicant's intent to move
forward with both parcels included, that permit would only be valid for one year from the
date of approval. If this phase is not completed before the permit lapses, a new permit
will be needed and the site will need to comply with any new rules in effect at that time.
The permit may be extended as allowed for in Rule A, §5 Please indicate your intention
for permitting at this time.
Because the project will involve 7.6 acres of land-disturbing activity, the project must conform to
the requirements in the RPBCWD Erosion and Sediment Control rule (Rule C, Subsection 2.1).
To conform to the RPBCWD Rule C the following revisions are needed:
Cl.The erosion control plan must include the following notes:
a. Natural topography and soil conditions must be protected, including retention
onsite of native topsoil to the greatest extent possible.
b. Additional measures, such as hydraulic mulching and other practices as specified
by the District must be used on slopes of 3:1 (H:V) or steeper to provide
adequate stabilization.
c. Final site stabilization measures must specify that at least six inches of topsoil or
organic matter be spread and incorporated into the underlying soil during final
site treatment wherever topsoil has been removed.
d. Soil surfaces compacted during construction and remaining pervious upon
completion of construction must be decompacted through soil amendment and/or
ripping to a depth of 18 inches (8 inches for single-family home properties) while
taking care to avoid utilities, tree roots and other existing vegetation prior to final
revegetation or other stabilization.
C2. All references to four inches (4") of topsoil shall be changed to read six inches (6") of
topsoil. Rule C. §3.1.f
C3. Include inlet protection for MNDOT culvert under State Highway 101.
C4. Provide space for contractor information. It is understood that the contractor is not yet
known.
C5. Indicate hydromulch or other rapid stabilization technique on the pond slopes above the
post grading silt fence. Update BMP quantities as appropriate. Rule C. §3.1.d
C6. Modify the "NOTE TO CONTRACTOR" on sheet 9 of 23 to reference the applicable
SWPPP.
C7. Add maintenance of rock construction entrances to "MIANTENANCE PROGRAM" on
sheet 11 of 23. Example: rock construction entrance to be maintained in good working
condition, free of ruts and exposed soils likely to result in vehicle tracking or other transport
of sediment off the site.
Because the project disturbs 7.6 acres, the project must conform to RPBCWD's stormwater
management rule as described in Rule J, Subsection 2. To conform to the RPBCWD Rule J the
following revisions are needed:
J1. The soil boring information provided gives a general indication of the soils expected at
the site; however, a soil boring within the footprint of the bottom contour of each
proposed BMP and extending at least 3 feet below the bottom of the section of the
proposed BMP must be provided. Given the presence of an existing Stormwater BMP
where the proposed infiltration basin is to be located, this is obviously problematic.
However, the Web Soil Survey indicates the soils to be Hamel loam which is known to
have a water table within one (1)foot of the surface. Two of the four borings on the
southern parcel indicate an elevated water table. Boring SB2 indicates the water at an
elevation of 899.0 feet or within one (1)foot of the bottom of the infiltration basin.
Additional supporting materials will be needed to demonstrate the required three (3)
foot separation to groundwater from the bottom of the infiltration feature.
J2. If a Phase I Environmental Site Assessment was performed please provide the results
to determine that there is no likely source of contamination in the proposed infiltration
area.
J3. Permit applicant must provide a maintenance and inspection plan. The plan must be
documented in a form acceptable to the District. A draft maintenance agreement is
available on the permits page of the RPBCWD website.
http://www.rpbcwd.orq/permits/)
Review of the additional materials may result in additional comments that will need to be
addressed prior to issuing a permit. We will do everything we can to ensure that we move you
through the permitting process as quickly as possible. Please contact me or Scott Sobiech (cc'd
on this e-mail, 952-832-2755)with any questions or concerns.
Thank you,