HomeMy WebLinkAboutValley Branch EAW CommentsNovember 11, 2016
Mr. Stephen Wensman
Planning Director
City of Lake Elmo
3800 Laverne Avenue North
Lake Elmo, MN 55042
Re: The Royal Golf Club Residential Development (EAW)
Dear Mr. Wensman:
Thank you for submitting a copy of the Environmental Assessment Worksheet (EAW) for the
proposed The Royal Golf Club Residential Development. The proposed project is located within the
Valley Branch Watershed District (VBWD). I offer the following comments on behalf of the
VBWD. The numbers correspond to the numbers in the EAW.
9. Land Use
Descriptions
a.ii Plans (Page 6): While the site does not lie within a Minnesota Department of Natural
Resources planned conservation corridor, the site is within an existing, somewhat connected,
natural greenway corridor, as shown on Figure 20 of VBWD's March 2013 Results of
Minnesota Routine Assessinent Method (MNRAM) for Evaluating Wetland Function
(attached).
a.iii Zoning, Floodplains (Pages 9-11): The VBWD recently completed more detailed
modeling of the Downs Lake watershed that used current climate and topographic data. The
modeling results and statistical analysis found the 1%-annual-chance (100-year) flood level of
Downs Lake to be Elevation 893.8. The VBWD will regulate to this flood level instead of the
FEMA base flood elevation of 893.0.
VBWD Rule 5, Standard 3, limits fill in lakes, ponds, and storage sites so that the cumulative
effect of all possible filling will not raise the 100-year flood level more than 0.1 foot. Flood -
storage replacement is allowed to conform to this VBWD rule, but wetlands should not be
filled or drained to provide the flood -storage replacement.
Structures will need to have their minimum floor elevations at least 2 feet higher than the
adjacent water bodies' VBWD-adopted 100-year flood level, as required in VBWD Rule 5,
Standard 2.
Easements covering all portions of the property that lie below the 100-year flood elevation of
lakes, wetlands, ponds, lowlands, and streams will need to be dedicated to the VBWD, as
required in VBWD Rule 5, Standard 3.
DAVID BUCHECK • LINCOLN FETCHER • JiLL LUCAS • EDWARD MARCHAN • ANTHONY HAIDER
VALLEY BRANCH WATERSHED DISTRICT • P.O BOX 838 • LAKE ELMO, MINNESOTA 55042-0538
www.vbwd org
Mr. Stephen Wensman
November 11, 2016
Page 2
Based on Figure 7 of the EAW, it's unclear if the proposed fill below the Down's Lake 100-
year flood level is being mitigated accurately and if the proposed homes will have minimum
floor elevations that are in compliance to VBWD rules.
Compatibility
9.b and 9.c. As noted in the EAW, the site is currently zoned for public and quasi -public open
space, rather than residential use. Much of the adjacent land is either open parkland or used for
residential housing with lots of at least 1 acre. The proposal is to create lots 0.4 to 0.75 acres.
The EAW states that the project is designed to preserve considerable forested buffers adjacent
to roadways. This will help hide the more densely developed lots from the existing, adjacent
land, but the conversion of forest to impervious surface will significantly change the character
of the area and decrease the natural habitat of the existing wildlife corridor. Additional
mitigation measures should be identified, evaluated, and implemented, including but not
limited to increasing the width of the corridor between Lake Elmo and the golf courses and
configuring the lots to preserve trees and other natural features.
11. Water Resources
Description
a.i Surface Water (pages 13-15)
This section of the EAW does not mention the VBWD's Project 1007 system that runs
through the site. Project 1007 directs outflows from the northern two-thirds of the
VBWD south and east to a storm sewer pipe along Interstate 94, which ultimately
discharges to the impaired Wild and Scenic St, Croix River. Approximately 20 square
miles drains through this site. Maintaining this conveyance through the site is critical.
Project 1007 is mentioned in the Stormwater section of the EAW on page 18.
Effects
b.3.ii Stormwater (pages 17-20)
Without seeing details, no determination can be made on the adequacy of the size and
location of stormwater management facilities (ponds and infiltration areas) shown on
Figure 7. Based on the concepts shown on the figure, additional infiltration areas will
be needed to treat runoff from all impervious surfaces. For example, no stormwater
management facility is shown near Rose Lake, and it's unlikely that the entire site
will be graded or equipped with storm sewer pipes to convey the runoff to the
proposed tiny infiltration area shown near the Lake Elmo outlet channel. However, as
noted in the EAW, a VBWD permit will be required and the project will be reviewed for
conformance to the VBWD rules and regulations when a permit application is submitted.
The VBWD will need to have unlimited access to all stormwater management facilities.
The facilities depicted at the northeast corner of the site are shown on the golf course
rather than in the residential subdivision. This could be problematic.
The project shows several cul-de-sacs. The VBWD encourages the developer to work
with the City of Lake Elmo to limit the amount of impervious surface for streets and cul-
de-sacs. Please see the attached factsheets. Reducing the amount of impervious surface
will reduce the construction cost to the developer, reduce the maintenance cost to the
City, and reduce the size of stormwater management facilities to construct and maintain.
b.3.iv.a Wetlands (page 21)
As noted in the EAW, a VBWD permit will be required and the project will be reviewed for
confonnance to the VBWD rules and regulations when a permit application is submitted.
Mr. Stephen Wensman
November 1 1, 2016
Page 3
Thank you for the opportunity to comment on the EAW. As the EAW indicates, a VBWD permit
will be required for the project. VBWD will review the project plans for confoimance to the VBWD
rules and regulations when a permit application is submitted. The items identified in this letter are
meant to identify potential issues and assist the project designers in protecting the water resources of
the area. If you have any questions or need clarifications, feel free to contact me at 952-832-2622.
Sincerely,
) )(
Jahn P. Hanson, P,E.
13arr Engineering Co.
Engineers for the Valley Branch Watershed District
c: VBWD Managers
k*,
Parks and Open Space
Subwatersheds
Impaired Stream (2010) Designated Trout Streams
High Priority Water Body I Assessed Wetlands
Central Region Green Infrastructure
Bikeways/Trails
0 3,000 6,000 9,000 12,000 15,000
r=Mnimil.1.1.11.111.111111.1111.11111111 Feet
Q.,14,2A Impaired Lakes (2010) Impaired Wetlands (2010) 0 1,000 2,000 3,000 4,000 5,000
- Somewhat Connected Natural Corridor Valley Branch Watershed r=n1=1"."11.1milaiiimilimmelmileiulli Meters
District Legal Boundary
Figure 20
HIGH PRIORITY AREAS
AND GREENWAY CONNECTIVITY
Valley Branch Watershed District, MN
Site Design to Reduce Stormwater Runoff
Street esign
31Paved
Standard width for residential collector streets, with
parking on both sides, Diniension Source: Maple Grove,
Minnesota.
Standard width for residential minor streets, with parking
on both sides. Dimension Source: Eden Prairie, Minn.
22' Paved
Driving Lanes
Allowing parking on only one side can further reduce the
width of low -volume residential streets. Distension
Source: Robert Engstrom Companies (Fields of St. Croix,
Lake Elmo, Minn.).
Many residential streets are wider than necessary.
They should be designed with the minimum
pavement width that will support the area's traffic
volume; on -street parking needs; and emergency,
maintenance, and service vehicles. For example,
consider creating one parking lane rather than two
for suburban residential streets.
In new subdivisions, reduce impervious surface by
reducing the total length of residential streets. (See
Open Space Subdivision Design.)
Encourage stormwater infiltration through the use of
curbless road designs and overland drainage
conveyance systems. On low -traffic streets, narrow
the pavement and allow grass shoulders to function
as an occasional parking lane.
Grass and/or
Aggregate Shoulder
24' ,1Varie
Paved Surface
Swale
Crowned, curbless road drains to roadside swales. Grass
shoulders function as occasional parking lanes. Dimen-
sion Source: Afton, Minn.
Benefits
• Reducing impervious surface results in less stormwater runoff and less infrastructure to accommodate it.
• Less pavement means lower costs for development and maintenance.
• Narrower streets discourage fast driving speeds and create a more pedestrian -friendly environment.
Design Guidelines
• Design residential streets with the minimum pavement width necessary to support; the traffic volume; on -
street parking needs; and emergency, maintenance, and service vehicles.
22 Alternative Stortmvater Best Management Practices Guidebook
Palley Branch Watershed District
Site Design to Reduce Stormwater Runoff
Cu1-de-Sac 1 esign
Cul-de-sac infiltration island accepts stortinvaterfrom
surrounding pavement.
Reducing the size or changing the shape of cul-de-
sacs can reduce the amount of impervious surface
in subdivisions. Cul-de-sacs should be designed
using the minimum radius that accomodates turning
of emergency, service, and maintenance vehicles.
Changing the radius from 40 feet to 30 feet can
reduce the impervious coverage by about 50%
(Schueler 1995).
Using turnaround options such as a T-shape can
also greatly reduce impervious surface.
A landscaped island in the center of the cul-de-sac removes impervious surface where driving does not occur.
This island can also be designed as a depression to accept stormwater runoff from the surrounding pavement.
A flat apron curb will stabilize roadway pavement and allow for runoff to flow from pavement into the cul-de-
sac's open center.
EMERGENCY
VEHICLE
0
PATH OF VEHICLE
OVERHANG
PATH OF RIGHT
FRONT WHEEL
Cul-de-sac with
offset island
Dimensions based
on AASHTO
Minimum Turning
Path for SU
Design Vehicle
60'
Cul-de-sac, no island
Dimension source: Eden
Prairie, Minnesota
T-shape turn -around
ted from Scheeler
Benefits
• With less impervious surface, less stormwater runoff will require management. Reducing stormwater
runoff protects downstream water bodies. Less paved surface also means lower development and mainte-
nance costs.
• Reducing pavement lessens the urban heat island effect, the increase in air temperature that can occur when
highly developed areas are exposed to the sun.
• Planted cul-de-sac islands are more attractive than wide expanses of pavement.
Design Guidelines
• Design cul-de-sacs with a radius of 39 feet or less.
• Include an unpaved, depressed island with a minimum radius of 20 feet.
Alternative Stormwater Best Management Practices Guidebook
Valley Branch Watershed District
19