HomeMy WebLinkAboutSP-23-009 - Supplemental - 0054 0056 West Twin Oaks Terrace (2)February 24, 2023
Marla Keene
mkeene@sburl.com
City of South Burlington, VT
180 Market St. South Burlington, VT 05403
RE: Kennedy Drive Stormwater Pond 2 Improvement Project
Dear Marla,
The City of South Burlington Stormwater Division is submitting the attached Application for Site Plan
Review for a proposed environmental restoration project located at the intersection of Kennedy Drive and
West Twin Oaks Terrace. The project proposes to expand the existing Kennedy Drive Stormwater Pond 2
area and retrofit the practice into a gravel wetland. The gravel wetland was designed to accommodate
the Water Quality Volume (WQv) and Channel Protection (CPv) storm events as outlined in the 2017
Vermont Stormwater Management Manual (VSMM). The proposed project is located in the Residential 7
Zoning District. This project qualifies as an environmental restoration project under the City of South
Burlington Land Development Regulations (LDRs), last revised May 2, 2022. The LDRs define an
environmental restoration project as
“a project authorized under the MS4 General Permit, TS4 General Permit, or Municipal Roads
General Permit (MRGP), that addresses a primary pollution source identified in a Vermont
Department of Environmental Conservation approved watershed implementation plan (i.e.
TMDL, Flow Restoration Plan, or Phosphorus Control Plan) and is not required for the purpose of
developing or redeveloping impervious surfaces.”
This project is identified in the Potash Brook Flow Restoration Plan, dated October 1, 2016. Please see the
attached Potash Brook FRP BMP Summary Sheet for Kennedy Drive Pond 2.
The majority of the project work will occur within the City of South Burlington Right-of-Way (ROW). The
ROW was expanded in 2006 when Kennedy Drive was widened to include a 7,790 sf parcel. There are no
existing buildings on this parcel. The current use consists of the existing Kennedy Drive Stormwater Pond
2. A portion of the proposed project extends onto the adjacent parcel on Twin Oaks Terrace. The City has
obtained a permanent easement on the adjacent parcel, which will allow for maintenance of the proposed
slope. There will be a temporary construction easement on the adjacent parcel as well. A copy of the deed
for the proposed easements for this project are attached to this application. This easement was also
approved by VTrans. The ROW Certification and Plan are attached to this narrative. The existing adjacent
parcel consists of two buildings and a parking area. There are no changes proposed to the existing
impervious on this parcel.
The project proposes to expand the existing stormwater treatment system and to retrofit the existing
pond into a gravel wetland, to increase phosphorus reduction. This will also conform the practice to the
current 2017 VSMM. The proposed gravel wetland will have two cells and will discharge into the wetland
to the west of the treatment practice. Pretreatment will be provided through the usage of a stormwater
separator, which will connect into the existing closed conveyance system that collects runoff from West
Twin Oaks Terrace. The total estimated cost for construction of this project is $283,500. Proposed
landscaping is shown on Sheet P-3.3 and consists primarily of shrubs and trees along the slope to the
south of the proposed gravel wetland. Of the total construction cost, $34,200 is slated for landscaping
improvements. The project is proposed to start in spring of 2023 and be completed by December 2023. A
completed plan set and cost estimate is attached to this application.
There is a Class II wetland located to the west of the existing stormwater pond. Kennedy Dr Pond 2 has
existing impacts to the wetland and its buffer and this project is proposing an additional 990.5 sf of impact
to the wetland buffer. The City has received a General Permit from the Wetlands Program for the State of
Vermont. The permit is #2022-0809.1 and is dated December 27, 2022. The permit is attached to this
application. The LDRs state that Class II Wetlands within a residential zoning district shall have a 100’
buffer per §12.06B(2)(b). The entirety of the project disturbance will occur within the wetland and the
100’ buffer, totaling 7,800 sf. Per §12.02B(5), stormwater facilities that are identified as part of an
environmental restoration project are qualified as Restricted Infrastructure Encroachments. The LDRs
state that Restricted Infrastructure Encroachment “may be allowed within Class I, Class II, or Class III
wetlands, and their associated buffers, without a waiver or modification provided that the applicant
demonstrates the project’s compliance with §12.02 and the following supplemental standards:
a) Roadway paved surfaces shall be no wider than necessary for the intended functional road
classification for the roadway and in no case shall the roadway paved surfaces be wider than 24
feet; and,
b) Roads that bifurcate a wetland or wetland buffer shall propose appropriate mitigation, such as
reduction or elimination of curbing and installation of cross culverts, to enable wildlife passage.
The project is not proposing any roadways, thus requirements (a) and (b) listed above are not applicable.
The total proposed impact to the Class II Wetland 100-ft buffer is 3,210 sf. See attached Sheets P-3.1 and
P-3.2 for existing and proposed wetland buffer impacts.
This project will require an amendment to the existing Act250 permit, which has been submitted and
reviewed under Project #4C1122-2. The Act 250 Permit amendment received a draft approval, with the
conditions that the wetland permit and local approval document be provided. The wetland permit was
obtained and submitted to the Act 250 office. This project has also gone through the National
Environmental Policy Act (NEPA) Review process and been approved.
The following attachments are provided with this application for your review:
Site Plan Review Application
o City of South Burlington
o Oak Hill Partners, LLC
Site Plan Review Application Narrative (this document)
Potash Brook FRP BMP Summary Sheet – Kennedy Drive Pond 2
Kennedy Drive Stormwater Pond 2 Improvement Project Plan Set
o Cover
o G-0.1 – General Notes, Legend & Drawing Index
o G-0.2 – General Notes & Quantity Sheet
o C-1.1 – Existing Site Plan
o C-1.2 – Proposed Site Plan
o C-2.1 – Gravel Wetland Details
o C-2.2 – Landscaping/Riparian Buffer Management Plan
o C-3.1 – Miscellaneous Details
o C-3.2 – Miscellaneous Details
o C-3.3 – Erosion Control Details
o P-3.1 – Existing Site Plan with Wetland Buffer Impacts
o P-3.2 – Proposed Site Plan with Wetland Buffer Impacts
Kennedy Drive Stormwater Pond 2 Improvement Project Engineer’s Opinion of Probable Cost
54 and 56 West Twin Oaks Terrace Easement Deed
Wetland Permit #2022-0809.1
Kennedy Drive Stormwater Pond 2 Improvement Project Wetland Buffer Impacts Plan Set
Draft Act 250 Permit
Abutters Information
If there are any questions, please reach out to Monika Ingalls at moingalls@southburlingtonvt.gov or
802-658-7961 x6108.
Thank you,
Monika Ingalls
Stormwater Project Manager