HomeMy WebLinkAboutSWWD Infiltration Basin Review Comments1
Stephen Wensman
From:Schilling, Andrew <aschilling@ci.woodbury.mn.us>
Sent:Wednesday, March 30, 2016 1:42 PM
To:John Rask
Cc:Loomis, John; Moore, Matt; Jenni Thompson; Stephen Wensman
Subject:RE: Inwood Landscape Plans
Hello, John.
See my comments and recommendations below regarding the latest filtration basin plans you provided (plans dated
3/17/16).
Inwood Filtration Basins ‐ SWWD Recommendations and Comments:
1. Filtration Basin Amended Soil Media:
a. As the majority of the basin bottom is covered by a dry creek bed (vs. vegetation), it is recommended the
filtration media be very lean on organics, following MN Stormater Manual's updated Mix B with 85% Sand, 15% organic
matter (MnDOT grade 2 compost and/or Peat) where the soil mixture has a phosphorus index between 12 and 30
mg/kg per Mehlich III (or equivalent) test.
b. For more information on Mix B ‐
http://stormwater.pca.state.mn.us/index.php/Comparison_of_pros_and_cons_of_bioretention_soil_mixes
2. Filtration Basin underdrain:
a. Geotextile fabric ‐ Geotextile fabric is no longer recommended around underdrains (due to clogging/failure
issues). Use choking stone (minimum 2" thickness between filtration media and larger diameter washed stone adjacent
to pipe) in place of geotextile fabric.
b. Ensure there are inspection/cleanout risers at upstream and downstream ends of the underdrain (at
minimum)
c. Add a gate valve at the downstream end of the underdrain (just before underdrain outlet) to allow for
performance optimization.
d. The Minnesota Stormwater Manual provides more information regarding underdrains:
http://stormwater.pca.state.mn.us/index.php/Design_criteria_for_filtration
3. Ensure top of all landscape material (top of sod thatch, shredded hardwood mulch, top of stone (dry creek bed) is set
2" below ribbon curb to allow sheet flow runoff to remain as sheet flow entering the filtration basin area.
4. Comments on Landscape Notes:
a. Note 2: Vinyl edging tends to be a maintenance issue in locations where stormwater flows must cross ‐
consider steel edging or grade to ensure flows do not cross edging locations
b. Note 5: Geotextile fabric is not recommend under the dry creek bed within the filtration basin's level
bottom. However, for maintenance and erosion control purposes, geotextile fabric is recommended under dry creek
bed sections adjacent to the ribbon curb and other side slopes.
Thanks,
Andy
Andy Schilling
Watershed Restoration Specialist
South Washington Watershed District
2
aschilling@ci.woodbury.mn.us
651‐714‐3717
Click for Directions
‐‐‐‐‐Original Message‐‐‐‐‐
From: John Rask [mailto:jrask@MIHOMES.com]
Sent: Monday, March 28, 2016 3:11 PM
To: Schilling, Andrew
Cc: Loomis, John; Moore, Matt; Jenni Thompson
Subject: RE: Inwood Landscape Plans
Andy,
I apologize. The e‐mail I sent last week got bounced back. It must have been too large. I was trying to send you the
complete grading plan along with the updated landscape plans.
We've made a few adjustments based on the suggestions of the City's landscape architect. These are still filtration
basins with underdrains. They are mislabeled on our landscape plans as infiltration basins. I will correct this. You will
find the filtration basin detail with the soil amendments specified on page 7 of the grading plan. This detail is the same
as the original submittal.
As previously mentioned, there is a homeowners association that is obligated to maintain these basins.
Thanks,
John
‐‐‐‐‐Original Message‐‐‐‐‐
From: John Rask
Sent: Friday, March 25, 2016 8:44 AM
To: 'Schilling, Andrew'
Cc: swensman@lakeelmo.org; Loomis, John; Moore, Matt; Jenni Thompson; Stephen Mastey
Subject: RE: Inwood Landscape Plans
Andrew,
Attached are the landscape plans for the islands.
Please feel free to call me or e‐mail with any questions.
Thanks,
John Rask | VP Land
M/I Homes of Minneapolis, LLC
Office: (763) 586‐7202 | Mobile: (612) 910‐9909
941 NE Hillwind Road | 300 | Fridley, MN | 55432 jrask@mihomes.com
‐‐‐‐‐Original Message‐‐‐‐‐
3
From: Schilling, Andrew [mailto:aschilling@ci.woodbury.mn.us]
Sent: Thursday, March 24, 2016 9:39 AM
To: John Rask
Cc: swensman@lakeelmo.org; Loomis, John; Moore, Matt
Subject: RE: Inwood Landscape Plans
John,
We need more information from you to clear up inconsistencies with the basin plans:
1. We've seen several different landscape plans for these basins ‐ send the most current to us.
‐ my comments regarding the basin final cover last week were based on plans dated 3‐26‐15 2. These basins
were originally permitted as filtration basins with underdrains. Is this still the plan?
‐ include details on soil amendments
These are a critical part of the stormwater management plan for the site, so we need to ensure they are built for long‐
term functionality.
Thanks,
Andy
Andy Schilling
Watershed Restoration Specialist
South Washington Watershed District
aschilling@ci.woodbury.mn.us
651‐714‐3717
Click for Directions
‐‐‐‐‐Original Message‐‐‐‐‐
From: Loomis, John
Sent: Thursday, March 24, 2016 8:36 AM
To: Schilling, Andrew
Subject: FW: Inwood Landscape Plans
John Loomis/SWWD
651‐714‐3714
‐‐‐‐‐Original Message‐‐‐‐‐
From: Moore, Matt
Sent: Wednesday, March 23, 2016 3:34 PM
To: Loomis, John
Subject: FW: Inwood Landscape Plans
Matt Moore
4
Administrator
South Washington Watershed District
2302 Tower Drive
Woodbury, MN 55125
P: 651.714.3729
C: 651.249.7096
mmoore@ci.woodbury.mn.us
www.swwdmn.org
Click for Directions
‐‐‐‐‐Original Message‐‐‐‐‐
From: Stephen Wensman [mailto:SWensman@lakeelmo.org]
Sent: Wednesday, March 23, 2016 3:13 PM
To: Moore, Matt
Subject: Inwood Landscape Plans
Matt,
I have attached the landscape plans for Inwood and you can see that the landscape plans for the infiltration basins show
only rocks with no plants. The grading plans do not match the landscape plans. The developer plans on installing
without native plants. Again, please let me know if you have any questions.
Stephen Wensman
Planning Director
City of Lake Elmo
651‐747‐3911