HomeMy WebLinkAboutSD-22-10 - Supplemental - 0500 Old Farm Road (77)1
Marla Keene
From:Dave Wheeler
Sent:Friday, July 8, 2022 1:36 PM
To:Marla Keene
Cc:Erica Quallen; Tom Dipietro
Subject:RE: SD-22-10 500 Old Farm Road O'Brien Eastview Final Plat - technical review
Hi Marla,
The Stormwater Section has reviewed the “Eastview” site plan prepared by Krebs & Lansing Consulting Engineers, dated
4/1/22 and last updated on 6/9/2022. We would like to offer the following comments:
1. This project is located in the Potash Brook watershed. This watershed is listed as stormwater impaired by the State
of Vermont Department of Environmental Conservation (DEC).
2. The project proposes to create greater than 1 acre of impervious area and disturb greater than 1 acre of land. It
will therefore require a stormwater permit and construction permit from the Vermont DEC Stormwater Division.
The applicant should acquire these permits before starting construction.
3. Exhibit 049: Stormwater narrative provided is for State stormwater permit. Applicant is requested to provide
supplemental narrative to address LDR requirements per §12.03(D) of the City’s Land Development Regulations.
4. Exhibit 131: The Site Plan provided for Gravel Wetland #3 appears to show Gravel Wetland #2 and Gravel Wetland
#9. The Overall Site Plan lacks fine detail for Gravel Wetland #3.
5. Exhibit 130: Gravel Wetland #3:
a. The two new 18” PVC vertical inlet pipes should be spaced further apart, with a lateral subsurface
perforated pipe connecting them, to increase mixing throughout a greater portion of the stone media.
This should be done in Cell #1 and Cell #2. As currently designed, there is a “dead-zone” in the western
corner of Cell #1 and in the western and southern corners of Cell #2.
b. There should be perforated lateral underdrain pipes shown connecting to the 6” PVC cross pipe on both
sides of the berm, as described in the detail on Sheet D-8.
c. The 6” PVC cross pipe between cells should be increased to a larger diameter pipe, to allow the water
levels in Cell #1 & Cell #2 to be in equilibrium.
d. There should be a perforated lateral underdrain connecting to the outlet structure, as described in the
detail on Sheet D-8.
e. Sheet D-8 and Sheet C-5 show different diameter vertical inlet pipes, 18” vs 24”. It is recommended to use
24”.
f. It is recommended that the applicant include secondary stone inlets around the vertical riser pipes, as
previously discussed with the engineer.
g. Sheet D-7 depicts a 24” diameter outlet pipe from the gravel wetland. Sheet C-5 shows an 18” pipe.
Confirm correct pipe diameter and confirm that the outlet pipe has adequate capacity to convey the 100-
year storm, as no emergency spillway is depicted.
6. Exhibit 148: The Site Plan provided for Gravel Wetland #4 appears to show a cross-country run of storm drain and
a rec path, but no gravel wetland is shown.
7. Exhibit 139: Gravel Wetland #4:
a. Refer to comments 5.a – 5.h above. These comments apply to Gravel Wetland #4 plan details as well.
b. The outlet pipe discharges to a location labeled as an existing drainage swale. The proposed grading in
this area is slightly vague as the existing drainage swale is shown running along a contour, rather than
downhill. Additional grading detail should be added to ensure a flow path from the 18” outlet pipe at
invert 376’ to the invert of the 15” culvert at invert 375’. Confirm the capacity of downstream
conveyance.
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c. In the HydroCAD model provided, the routing table shows the 48”x6” weir in the outlet structure with an
invert elevation of 382.5’, while Sheet D-9 shows an elevation of 382.1’. Confirm correct elevation and
update plans accordingly.
8. Exhibit 142: Gravel Wetland #5:
a. Refer to comments 5.a – 5.h above. These comments apply to Gravel Wetland #5 plan details as well.
b. The 12’ wide stabilized grass maintenance drive includes a 90 degree turn with no turning radius
considered for potential large equipment that may need to access the gravel wetland for maintenance
purposes. Additionally, there is a retaining wall and trees that may prohibit such vehicles from making the
turn.
c. How will water from discharging from Gravel Wetland #5 reach surface waters without causing erosion?
Is this system discharging into a fence and the dog park?
9. Exhibit 130: Gravel Wetland 6A
a. Refer to comments 5.a – 5.h above. These comments apply to Gravel Wetland #6A plan details as well.
b. Retention within Gravel Wetland 6A is proposed to rely on a berm constructed above final grade. The
engineer should include an additional cross-section detail calling out soil material that is acceptable for
the berm to ensure there is not seepage through the berm onto the sidewalks.
c. No emergency spillway is depicted. Confirm that the 18” diameter outlet pipe has adequate capacity to
convey the 100-year storm.
10. Exhibit 133: Gravel Wetland 6B
a. Refer to comments 5.a – 5.h above. These comments apply to Gravel Wetland #6B plan details as well.
b. The callout “New Outlet Structure 6A” should read “New Outlet Structure 6B”.
c. No emergency spillway is depicted. Confirm that the 18” diameter outlet pipe has adequate capacity to
convey the 100-year storm.
11. Exhibit 145: Gravel Wetland 7
a. Refer to comments 5.a – 5.h above. These comments apply to Gravel Wetland #7 plan details as well.
b. In the HydroCAD model printout provided for Gravel Wetland 7, it indicates the peak water level elevation
is 328.07’, which is above the invert elevation of the CPv orifice. The 1” CPv orifice should be drilled in the
4” PVC cap at a higher elevation than 328.07’.
c. The emergency spillway is shown discharging right to a gravel path. Based on prior experience from the
Wet Pond & Infiltration Basin A, in an earlier phase of the Hillside development, the gravel path is likely
to wash out in this location. The plans should be revised to either utilize a culvert, footbridge or other
solution to avoid this conflict.
d. The applicant should be aware that the existing City ordinance places restrictions on the City’s ability to
accept stormwater treatment infrastructure that serves commercial property.
12. Exhibit 149: Gravel Wetland #8:
a. Refer to comments 5.a – 5.h above. These comments apply to Gravel Wetland #8 plan details as well.
b. Access to Gravel Wetland #8 is provided by a long and potentially steep access road that originates on
Potash Road. Provide more information. What options were considered for gravel wetland location and
access? There appears to be a 60’ wide road proposed between lots 41 and 42. Would this be a better
access route to the gravel wetland?
c. What size pipe will be installed under the path downstream of gravel wetland #8? Provide calculations for
pipe sizing.
d. In Exhibit 017: Class III Wetland Description and Impact Memo, there is a statement made that is
potentially in conflict with the stormwater narrative provided by Krebs & Lansing. The wetlands memo
indicates that “These sites have very limited drainage areas (i.e., there is little drainage into them), have
no outlets, and act as sumps (rainfall and snowmelt only leaves by evaporation and by percolating into the
soil). They are not connected to or associated with streams, ponds, or any open water.” However, the
HydroCAD modeling provided by Krebs & Lansing shows a 20 cfs discharge rate during pre-development
conditions to SN010, just downstream of the impacted wetland.
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i. If the true pre-development conditions match what the wetland narrative says, then the
HydroCAD model should be revised to reflect those conditions.
1. What is the drainage area to the impacted Class III wetland? Was this area removed from
the pre-development HydroCAD model? Are there any ditches directing runoff into this
wetland?
e. The applicant should be aware that the existing City ordinance places restrictions on the City’s ability to
accept stormwater treatment infrastructure that serves commercial property.
13. The landscaping plans depicting the gravel wetlands, including, but not limited to: L-113, L-104B, L-110, L-119, and
L-111 should be revised to allow access to the forebay for sediment removal and provide a greater opening into
each cell of the gravel wetland for maintenance access purposes.
14. Storm drains proposed to be taken over by the City will require a 20’ easement, centered on pipe, free of
structures or obstructions.
15. Tress should not be planted within easements for storm drains proposed to be taken over by the City.
16. Back flow prevents are recommended for all footing drains that connect to drainage infrastructure that is
proposed for public acceptance.
17. EPSC Plans should be revised to show spacing of silt fence consistent with Silt Fence Spacing Chart on Sheet D-
10, as well as J-hooks where silt fence terminates, as contractors tend to follow what is shown on the approved
plan. Initial phases of construction also do not reflect the fully built-out condition illustrated on the EPSC plans.
18. The DRB should include a condition requiring the applicant to regularly maintain all stormwater treatment and
conveyance infrastructure.
Thank you for the opportunity to comment,
Dave
Cell (802) 734-1102
Notice - Under Vermont’s Public Records Act, all e-mail, e-mail attachments as well as paper copies of documents received or prepared for use in matters concerning City business,
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From: Tom Dipietro <tdipietro@southburlingtonvt.gov>
Sent: Friday, July 8, 2022 11:22 AM
To: Marla Keene <mkeene@southburlingtonvt.gov>
Cc: Erica Quallen <equallen@southburlingtonvt.gov>; Dave Wheeler <dwheeler@southburlingtonvt.gov>
Subject: RE: SD-22-10 500 Old Farm Road O'Brien Eastview Final Plat - technical review
Marla,
On behalf of the Department of Public Works, I’d like to provide the following comments on the O’brien Eastview
Project:
General
Please calculate signal warrants for residential and partial-build at proposed signals at Kimball Ave/Old Farm Rd
and Kimball Ave/Potash Rd to determine approximately when signal will be required.
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Confirm lengths of left turn lanes are sufficient for peak hour traffic at Kimball Ave/Old Farm Rd and Kimball
Ave/Potash Rd.
Smooth angle (approx. 30 degrees) at end of parking stalls for ease of maintenance.
The application narrative (Exhibit 000 - Page 29) proposes the open space and path elements that will be eligible
for City acceptance and ownership. More discussion will be necessary with the DPW and Recreation
Departments to confirm the future public ownership of these areas. Also, additional details regarding the
proposed maintenance agreements will be necessary.
Phasing plan (Exhibit 123)
o Has the project applied for Construction General Permit (CGP) coverage from the State of Vermont? The
phasing plan must account for any requirements related to any maximum area to be “opened up” for
construction contained in the CGP.
o The board should consider a condition indicating that, “If discharges of sediment and nutrients are
leaving the site then a new phase may not commence until the issues are corrected and the site
stabilized to the satisfaction of the Director of public works, or his designee”. Make compliance with
CGP a condition of the approval.
o Language contained in the “triggers” section of the column should be reviewed for clarity. In some
cases, the language is imprecise (e.g. “any time prior to or after completion of..”, see phases 5 and 6)
and does not appear to place any restrictions, or provide clarity, regarding when work will take place.
If utilities are to be turned over to the City, then additional efforts may be necessary to place infrastructure
within existing and/or proposed road ROWs. Any utility easements proposed for City acceptance must be
centered within a 20’ wide easement.
Record drawings shall be prepared for any infrastructure proposed for City acceptance.
Exhibit 099
Please show conduit running through the sleeves under the roadway.
Please show the location of pushbuttons (are these located where the “vehicle detection” symbol is used?) and
direction of pedestrian signal heads so that MUTCD and ADA compliance can be ensured.
The southern corner requires two pedestal poles for ADA compliance: one in the existing location for the Old
Farm Road crossing and an additional one for the eastbound Kimball Ave crossing. Perhaps cantilever pole #3
could be relocated and pushbutton and pedestrian signal head could be mounted on that pole.
3 second leading pedestrian interval feels too short for the crossings. Consider increasing to 6 seconds.
Flashing Don’t Walk across Kimball Ave must be at least 11 seconds.
Please add junction box detail.
Exhibit 100
Please show conduit running through the sleeves under the roadway
Please show the location of pushbuttons (are these located where the “vehicle detection” symbol is used?) and
direction of pedestrian signal heads so that MUTCD and ADA compliance can be ensured.
3 second leading pedestrian interval feels too short for the crossings. Consider increasing to 6 seconds.
Please add junction box detail.
Flashing Don’t Walk across Potash Rd must be at least 13 seconds.
Exhibit 101 & 102
Mast arms should be of standard length and be rounded to the nearest 5’
Exhibit 104
Under General Specifications, please add:
o “The signal system shall not operate without the appropriate pavement markings and related signing in
place.”
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o “The signal heads shall be covered with an opaque covering until such time as the signal system is
functional. At no time should the heads be viewed without having some form of signal indication, i.e.
flashing operation or sequencing as per plan.”
o “Traffic signals installed at new locations shall be activated only upon the approval of the engineer and
after flashing for a minimum of 48 hours.”
Under Signal Equipment Specifications, please:
o Spell out NEMA, IMSA, and ITE before abbreviating
Exhibit 106
Add “left lane must turn left” (R3-7) on westbound Kimball Ave approach at Old Farm Road to match eastbound
approach
Exhibit 107
Add speed hump signs on Old Farm Road approaching Mabel Way.
Align building access sidewalk and crossing on Old Farm Rd at Mabel Way.
Recommend adding handicap parking and van accessible signs (R7-8, R7-8P) on handicap spot on Old Farm Road
parking .
Sidewalk and driveway entry are misaligned at Old Farm Rd and driveway south of O’Brien Farm Rd Ext.
Is there curb between the driveway and sidewalk on driveway off Old Farm Rd south of O’Brien Farm Rd Ext?
Please add if there is not already. It is unclear from the plans
Relocate path intersection to be closer to perpendicular south of Mabel Way.
Exhibit 108
Detectable warning surface and crosswalk needed at Leo Lane sidewalk crossing.
Recommend adding handicap parking and van accessible signs (R7-8, R7-8P) on handicap spot on Old Farm Road
parking.
Exhibit 109
Why does the sidewalk get pushed up to the road adjacent to speed hump along Old Farm Rd?
Recommend adding handicap parking and van accessible signs (R7-8, R7-8P) on handicap spot on O’Brien Farm
Road Ext parking
Sidewalk and driveway entry are misaligned on west side of O’Brien Farm Rd Ext
Exhibit 111
Narrative describes no signal at O’Brien Farm Rd and Old Farm Rd being warranted or shown in the plans (page
3) but Exhibit 111 shows incomplete signal plans for this intersection.
Exhibit 119
Off of Potash Road, between lots 41 and 42 there is a 60’ wide access indicated. Confirm that this road is
proposed to remain private? It appears as if there is a property line missing that would make this road its own
lot.
Exhibits 118 & 119
Proposed stormwater easements contain the phrase “…for the benefit of the City of South Burlington…”. For
improved clarity, consider adding this phrase to all easements proposed for future City acceptance. It should be
clarified whether or not the blue easements are proposed to be given to the City.
Exhibit 124
Barn Road terminates without a hammerhead turnaround which is not consistent with Article 15.A
(Subdivisions) of the LDRs. When the road becomes public, we’ll plow past the driveway for unit 38-5, but not to
the end of the road until a connection is made.
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Consider adding a sidewalk on at least one side of the connector road between Old Farm Rd and O’Brien Farm
Rd Ext
Exhibit 135 & 136
There appears to be a drainage line along the frontage of lots 26-29. Confirm that this line is to remain privately
owned?
Exhibit 140
The applicant should confirm that the sewer line east of the homes on Mabel Way is proposed to become
public. If so, what steps will be taken to ensure that the City has continuous, unencumbered access to this
infrastructure? No structures shall be placed within the proposed easement.
Can the proposed storm drain near station 6+80 be moved slightly so that it is not in the crosswalk?
Exhibit 145
Confirm that the sewer line located primarily on lot 41 will remain private until it reaches the City owned
infrastructure within Kimball Avenue.
The 10’ paved multi-use path stops near wetland #7. The applicant should continue this path to the east until it
reaches the end of the property along Kimball Avenue.
Exhibit 147
Cyclists traveling south on path along Potash Road will not be able to make the turn and head NW up the
proposed 10’ paved multi-use path. What other configurations were considered? Is another section of path
necessary to facilitate a connection from those traveling south on Potash Road that wish to connect to Mabel
Way? There are 3 pedestrian elements located in a small area.
It was my understanding that this property would provide a multi-use path connection from the south end of
Potash Road to Tilley Drive. As proposed, the path stops at the property line.
Exhibit 150
The sidewalk along Old Farm Road is proposed to dead end at Hinesburg Road. In order to facilitate pedestrian
traffic, a connection needs to be made to the existing path located to the south (near Tilley Drive) that currently
dead ends on Pizzagalli Properties, LLC.
The sidewalk proposed along Old Farm Road is shown with no green space between it and the road (in some
sections). Consider moving the sidewalk to the edge of the ROW to allow for green space. The sidewalk as
proposed has some sharp turns/angles along its length. It will be difficult to maintain. The applicant will need to
modify this to provide a more maintainable sidewalk. This will likely require relocation of existing drainage
infrastructure in the ROW. It is also recommended that the plans include stone splash pads at pipe outlets. The
City’s minimum culvert pipe size is 15” and driveway culvert is recommended to be 18”
(https://vtrans.vermont.gov/sites/aot/files/operations/TheOrangeBook.pdf)
It is the DPW’s desire that this sidewalk along Old Farm Road be constructed as part of the O’brien Hillside
project. Based on DPW’s current work load, if construction of this path were to become a City responsibility it
would likely not be completed in a timeframe that would match up with home construction for the proposed
development.
You’ll soon be receiving a second email containing comments on stormwater and drainage from Dave.
Please reach out if you have any questions on the above. Thank you for the opportunity to comment.
-Tom
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From: Marla Keene <mkeene@southburlingtonvt.gov>
Sent: Wednesday, June 22, 2022 4:40 PM
To: Jay Nadeau <jay.nadeau@champlainwater.org>; Terry Francis <tfrancis@southburlingtonvt.gov>; Tom Dipietro
<tdipietro@southburlingtonvt.gov>; Adam Cate <acate@SouthBurlingtonVT.gov>; Dave Wheeler
<dwheeler@southburlingtonvt.gov>; Craig Lambert <clambert@southburlingtonvt.gov>
Subject: SD-22-10 500 Old Farm Road O'Brien Eastview Final Plat - technical review
Hi everyone,
This application will be reviewed by the Board at the July 19 DRB hearing. This is the last review of the large O’Brien
Eastview project. I am sending this email early so you can allocate time appropriately. If you’d like to meet on this
project, please let me know. Please provide comments by no later than Friday July 8. This hearing will take place over
the course of several meetings, so you are welcome to request more information in your comments.
Just a reminder, comments you provide are inserted directly into the staff report for the project, so please frame your
response for public consumption.
Draft Project Description
Final plat application #SD-22-10 of O’Brien Eastview, LLC to create a planned unit development of six existing parcels
currently developed with three single family homes and a barn and totaling 102.6 acres. The development is to consist
of 155 homes in single family, duplex, and three-family dwellings on eleven (11) lots totaling 23.9 acres, eighteen (18)
commercial development lots totaling 39.8 acres, and 25.2 acres of undeveloped or recreational open spaces, 500 Old
Farm Road.
\\192.168.9.13\apps\USERS\Planning & Zoning\Development Review Board\Applications\2022\SD-22-10_500 Old Farm
Road_OBrien Eastview_FP_2022-07-19
Thanks,
Marla Keene, PE
Development Review Planner
City of South Burlington
180 Market Street
South Burlington, VT 05403
(802) 846-4106
www.southburlingtonvt.gov
Notice - Under Vermont’s Public Records Act, all e-mail, e-mail attachments as well as paper copies of documents received or prepared for use in matters
concerning City business, concerning a City official or staff, or containing information relating to City business are likely to be regarded as public records which
may be inspected by any person upon request, unless otherwise made confidential by law. If you have received this message in error, please notify us immediately by
return email. Thank you for your cooperation.