Eng. Comments - 22-04 10500 and 10520 Great Plains Blvd Conceptual PUD
Memorandum
To: MacKenzie Young-Walters, Associate Planner
From: Erik Henricksen, Project Engineer
Joe Seidl, Water Resources Engineer
CC: Charles Howley, Public Works Director/City Engineer
George Bender, Assistant City Engineer
Joe Seidl, Water Resources Engineer
Charlie Burke, Public Works Operations Manager
Date: 2/18/2022
Re: 10500 and 10520 Great Plains Boulevard Conceptual PUD Review –
Planning Case No. 2022-04
EASEMENTS
The preliminary plat provided with the Conceptual PUD materials, dated 12/4/2018 and
produced by James R. Hill, Inc., illustrates typical 10 foot public drainage and utility easements
(DUE) along all property lines. Additional public DUEs will be required over public utilities
(only watermain at this phase) extended into the property as discussed under the “Sanitary Sewer
and Watermain” section of this report. The dimensions of the DUE must be adequate to
properly repair and maintain the utility; the minimum for watermains is typically 20 feet wide,
centered over the main, due to their typical installation depth of 7.5 feet, however additional
DUE may be required depending on the plans that will be provided.
Any and all existing easements must be vacated prior to recording of the final plat.
Based on Carver County property information there appears to be two parcels abutting the
preliminary plat’s western property lines that are listed as “Parcel ID: Gap”. It is unclear if these
parcels are being considered in the lot combination of the Conceptual PUD, or if they are being
considered a part of the adjacent lot to the west (PID #250361300). Clarification regarding the
status of “Parcel ID: Gap” in conjunction with the proposed plat will be required prior to
recording of the final plat from either the County or the applicant.
The preliminary plat abuts and gains access from Carver County right-of-way. Thus, the
applicant must coordinate with Carver County regarding any additional considerations and
potential conditions associated with easements for the property as well as any requirements
associated with ingress/egress and construction activities such as during grading and hauling
operations.
EXISTING CONDITIONS SURVEY
The existing condition survey, dated 1/28/2022 and produced by James R. Hill, Inc., will need to
be updated upon resubmittal to incorporate the following information, as necessary:
· Topographic data 100 feet beyond the property boundary
· Illustration of existing features that would impact the site’s ingress/egress (e.g. the full
extents of Flying Cloud Drive which includes the median near the site’s entrance)
· Utilities on or adjacent to the property, including location, size and invert elevation of
storm sewers, catch basins and manholes; location and size of water mains (including
casings) and hydrants; location of gas mains, high pressure lines, fire hydrants, electric
and telephone lines, and street lights. The direction, distance to, and size of such
facilities shall be indicated.
· Wetlands
· Bluff impact zones
· Sewage treatment systems and associated conveyance systems
· Existing easements and associated recording document numbers
· Property information within 150 feet of the property’s boundary
· Retaining wall elevations
WETLANDS
A study completed by Kjolhaug Environmental Services in 2021 shows there are no wetlands
within the project site. City records show there is one wetland just south of the project site located in
the drainage ditch along County Road 101 (Great Plains Blvd). This wetland has been classified as
a manage type 2 wetland in the City’s Surface Water Management Plan. A 1992 delineation report
indicates the source of water as surface water runoff and the route of outflow is a culvert to the
Minnesota River.
The preliminary plans submitted with the Conceptual PUD show grading in close proximity to
the wetland which is near the proposed access to the site. Article VI, Chapter 20 of City Code
describes buffer strip and setback requirements. For example a 10 to 30 foot buffer strip with an
average of 20 foot width for manage type 2 wetlands. There is also a 30-foot setback from the
buffer strip so the building setback should be from 40 to 60 feet averaging 50 feet away from the
edge of a manage type 2 wetland. The wetland buffer and wetland setback should be shown on the
grading plan and stacked in the field prior to construction. The preliminary plans appear meet the
wetland buffer and setback requirements.
BLUFFS
There is a steep slope located on the west side of the property; the bottom generally follows the
750 contour of the property and the top of the follows the 772 -774 contours. The steep area is
called out in the preliminary plans as a bluff, however because this area was created from
grading completed as part of a development project in 1996 it is not a natural slope and therefore
does not meet the City's definition of a bluff. The Lower Minnesota River Watershed District
(LMRWD) also regulates steep slopes within their jurisdiction. The applicant will need to
coordinate with the watershed district to confirm if the project triggers any regulations as defined
in Rule F – Steep Slopes.
RETAINING WALLS
Preliminary plans provided with the Conceptual PUD submittal indicate that retaining walls may
be required for the development. These walls are shown around the northern and western
portions of the property. Portions of the retaining walls illustrated are shown to be located
within public drainage and utility easements along the western property lines. An encroachment
agreement would be required for any retaining walls located within public easements.
Portions of the retaining walls are illustrated to be either close to or directly over the western
property line. Due to the proximity to the property line, the construction of these walls would
require construction activities to occur on the abutting property. The construction of any
improvements that impact or require access to abutting properties must have the appropriate
right-of-entry agreements and/or temporary construction easements prior to construction
operations commencing.
Retaining walls over 4 feet in height shall be constructed in accordance with plans prepared by a
registered engineer and shall be constructed of a durable material (smooth face concrete,
masonry/mortared, railroad ties and timber are prohibited). It should be noted that the height of
any retaining wall is measured from the top of the wall to the bottom of the footing (not to the
top of grade adjacent to the bottom of the wall).
ACCESS
Access to the site is currently had from Flying Cloud Drive (CSAH 61) and is located near the
western property line. The preliminary plans indicate that the current access will remain and no
additional accesses to the surrounding Carver County rights-of-way are proposed. The
development will be required to construct a commercial driveway access in accordance with City
Standards. Any comments or conditions by Carver County associated with impacts to their
rights-of-way must be adhered to and all permits required must be obtained prior to construction
activities commencing.
It appears no turnaround is provided in the preliminary plans. In accordance with Section 20-
1122 of City Code a turnaround is required when access is had from a state highway, county road
or collector roadway. As access is being had from CSAH 61 a turnaround will be required that
can adequately facilitate the turning movement of the largest anticipated design vehicle for the
site or the City’s largest fire truck, whichever is greater.
GRADING AND DRAINAGE
The existing conditions plansheet and drainage maps included in the Conceptual PUD submittal
show an existing building near the center of the property with access to Great Plains Boulevard
provide by an asphalt parking area and gravel driveway. Stormwater runoff general flows from
north to south down the slope of the site where it enters a drainage swale along Flying Cloud
Drive. The drainage swale conveys stormwater from west to east. Stormwater leaves the site by
way of an existing 48” culvert under Flying Cloud Drive which conveys the stormwater to the
South through Bluff Creek and ultimately outleting to the Minnesota River.
The preliminary plans provided with the Conceptual PUD submittal show a significant amount
of grading. The design steepens the hill on the northeast side of the site to create a flat area
conducive for the four proposed buildings with access and parking. The proposed design uses
combination of drainage swales and stormwater infrastructure to collect and convey stormwater
into a Best Management Practice (BMP) located on the southwest corner of the property. The
design shows stormwater being conveyed from the proposed BMP to the existing swale along
Flying Cloud Blvd through an outlet control structure. Any impacts to Carver County’s right-of-
way must be approved and permitted by the County prior to construction activities. The overall
design of the stormwater infrastructure mimics the flow path of the existing condition and acts to
convey stormwater runoff from impervious surfaces through water quality BMPS. A more
detailed analysis of stormwater volumes and rates may be required to show the wetland onsite is
not negatively impacted by the proposed design.
EROSION PREVENTION AND SEDIMENT CONTROL
The proposed development will exceed one (1) acre of disturbance and will, therefore, be subject
to the General Permit Authorization to Discharge Stormwater Associated with Construction
Activity Under the National Pollution Discharge Elimination/State Disposal System (NPDES
Construction Permit). The applicant has prepared and submitted a preliminary Surface Water
Pollution Prevention Plan (SWPPP) and generally appears feasible. The SWPPP is a required
submittal element for preliminary plat review. No earth disturbing activities may occur until an
approved SWPPP is developed. This SWPPP shall be a standalone document consistent with the
NPDES Construction Permit and shall contain all required elements as listed in Parts III and IV
of the permit. The SWPPP will need to be updated as the plans are finalized, when the
contractor and their sub-contractors are identified and as other conditions change.
SANITARY SEWER AND WATERMAIN
Currently, municipal sanitary sewer and potable water services are not available to the site.
During the build-out of the Highway 101 Realignment project, which was substantially
completed in 2021, public sanitary sewer mains and water mains were extended along the
corridor. However, these newly extended utilities are not fully active nor ready for operation to
service properties, as such the site does not have adequate public sanitary and water to fully
serve the development’s needs.
In 2014, a Highway 61 corridor study was conducted in response to several near and long-term
infrastructure projects at the time (e.g. Highway 101 Realignment, CSAH 61 reconstruction,
flood mitigation projects, etc.) which prompted the City to investigate the feasibility of extending
public utilities to the southern portion of the City. The study, known as “County Road 61
Corridor Plan”, conducted by SRF in association with Hoisington Koegler Group, Inc.,
determined that utility extensions were feasible within the study area. The image below, taken
from Figure 3.1 of the City’s 2040 Comprehensive Plan, depicts the City’s existing and planned
sanitary sewer in this area (planned water system build-out generally adheres to the same areas
and alignments).
The proposed development falls within the southcentral region of sanitary subdistrict LB-1 (the
Lower Bluff Creek District). The 2014 study estimated costs and fee revenue associated with
extending City utilities to the study area, along with estimated utility assessments per acre, which
are shown in Tables 1 and 2.
With a lack of adequate city utilities in the area, the development will be required to provide
private utility services (sanitary sewer and potable water) to adequately meet the needs of the
development. The City has preliminarily agreed to allow the development to tap into the public
watermain which was extended with the Highway 101 Realignment project, but only to service
the development’s fire suppression needs. At this time there is not sufficient demand along the
extended watermain to supply water to the quality standards that the City requires for
consumption. This is important to note because the preliminary plans provided indicate the
existing well on-site is proposed to be abandoned. If the site will have any fixtures requiring the
use of water other than for fire suppression needs, a private source of water supply must be used
for those fixtures.
The preliminary plans indicate tapping of the existing public watermain for fire suppression
needs at the southwest corner of the property. As shown on the preliminary plans this would be
infeasible as the watermain was housed in a casing at the location, and would be required to be
extended further west to facilitate the connection. Regardless, the development will be required
to extend the public watermain to the western property line, and the extension into the site must
be along or near the improved private access to allow for reasonable access for future repair and
maintenance. Adequate public drainage and utility easements will be required over the public
main as it extends into the site. Private fire laterals can then be tapped from the public main as
necessary.
The property and potential future properties associated with this developable area will be
specially assessed for the extension of the public sanitary sewer when they connect.
STORM WATER MANAGEMENT
The project site is located within the Lower Minnesota River Watershed District (LMRWD). The
LMRWD is the LGU that administers NPDES Construction Permits for stormwater
management. The proposed development will exceed the one (1) acre of new impervious area
and will therefore require permanent stormwater BMPs to be constructed as part of this project
and maintained by the owner. The project will be subject to stormwater regulations outlined
under LMRWD Rule D including rate, volume, and water quality.
The City of Chanhassen also regulates the design, construction, and maintenance of stormwater
infrastructure. Article VII, Chapter 19 of City Code describes the required storm water
management development standards. Section 19-141 states that “these development standards
shall be reflected in plans prepared by developers and/or project proposers in the design and
layout of site plans, subdivisions and water management features.” A stormwater maintenance
agreement and associated operations and maintenance plan is required for all private stormwater
BMPs.
Preliminary plans provided with the Conceptual PUD submittal show stormwater treatment and
rate control from a wet pond with an incorporated filtration bench BMP located on the southwest
corner of the property. The stormwater BMP appears to be properly sized for the impervious
surface proposed in the plans. The design of the BMP is highly dependent on soil types and
infiltration rates of the underlying soils. Soil borings, infiltration testing and an associated
geotechnical report will be needed to confirm the design of the stormwater BMP. No
geotechnical report was included as part of the Conceptual PUD submittal.
The City’s water resources engineer reviewed the preliminary plans provided with the
Conceptual PUD. Specific comments regarding the design of stormwater infrastructure and
BMPs were provided to the applicant.
STORM WATER MANAGEMENT FEES
In 2005 a Stipulation of Settlement (Court File No. 10-CV-05-48) between PCH Development,
LLC and the City of Chanhassen was agreed to regarding the park dedication fees and surface
water management fees surrounding the subdivision of the “Paws Claws and Hooves Addition”
subdivision (PC #2003-04 and the property of this Conceptual PUD). The surface water
management fee was reduced to $9,900.00 and was paid on 7/25/2005. The settlement
agreement states, “If all or any part of the property is changed to a different principal use or
further subdivided, the property shall be subject to payment of additional park dedication and
surface water management fees based upon the rates in effect at that time applicable to the
proposed use and type of municipal approval requested.” However, as the stipulation was
between the property owner and the City and was not required to be memorialized against the
property, if the property owner changes from PCH Development, LLC no stormwater fees will
be required if the PUD is approved. If the property is subdivided in the future, stormwater fees
will be collected at the rate in affect at the time of platting, minus the $9,900.00 already paid.