HomeMy WebLinkAboutSD-24-11 - Supplemental - 0252 Autumn Hill Road (14)1
Marla Keene
From:Monika Ingalls
Sent:Monday, July 29, 2024 10:36 AM
To:Marla Keene
Subject:Fw: EXTERNAL: Bolduc Subdivision #SD-24-11 - Storm Comments
FYI, I worked out all of my comments with Bryan and Noah, so I don't have any further comments for them.
Thanks,
Monika
Monika Ingalls
Stormwater Project Manager
Department of Public Works
City of South Burlington
104 Landfill Road
South Burlington, VT 05403
Office: (802) 658-7961 Ext. 6108
Cell: (802) 556-4996
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: Monika Ingalls <moingalls@southburlingtonvt.gov>
Sent: 29 July 2024 10:35
To: Noah Palker <NPalker@olearyburke.com>; Bryan Currier <bcurrier@olearyburke.com>
Subject: Re: EXTERNAL: Bolduc Subdivision #SD-24-11 - Storm Comments
Hi Noah,
Thanks for your responses. I don't have any further comments.
Regards,
Monika
Monika Ingalls
Stormwater Project Manager
Department of Public Works
City of South Burlington
104 Landfill Road
South Burlington, VT 05403
Office: (802) 658-7961 Ext. 6108
Cell: (802) 556-4996
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.
2
From: Noah Palker <NPalker@olearyburke.com>
Sent: 26 July 2024 14:18
To: Monika Ingalls <moingalls@southburlingtonvt.gov>; Bryan Currier <bcurrier@olearyburke.com>
Subject: RE: EXTERNAL: Bolduc Subdivision #SD-24-11 - Storm Comments
Hello Monika,
Thanks for reviewing, please find responses to the additional comments:
The gravel wetland should be sized to treat impervious proposed for the 1.97-acre lot. While this lot will not
be constructed at the same time, it is part of the same plan of development as the 6-acre and 16.44-acre
lots and thus the 1.97-acre lot is subject to Section 13.05 of the LDRs.
We included the impervious surface from the duplex in the design. However, it was realized that a
small amount of impervious surface was not accounted for when accommodating the Fire
Marshall's comments on driveway width and the turn-around. I recalculated the impervious areas
and added a little extra as a safety factor. This change did not significantly affect the design, except
for the need to slightly raise some of our outlets by a couple tenths of a foot. Please see the revised
HydroCAD model and plan reflecting these adjustments.
While I agree the storage difference between the proposed orifice and what is in the modeling is minimal,
please use actual inverts in the HydroCAD modeling to avoid confusion in the future.
Understood.
On Sheet 4, Elev. E is called out at 360.57 in the gravel wetland detail, but is called out as 359.57 in the
gravel wetland schedule. Please revise.
The elevations have been revised and are consistent across the detail and the schedule.
Per Section 13.05.E.4.c., driveway culverts must have a minimum of 12" of cover. Please either lower the
culvert invert or raise the drive grade to achieve this cover.
The proposed driveway elevation above the culvert is 363.1’ while the top of culvert is 362’.
Therefore, we are proposing 1.1’ of cover which is larger than the required minimum of 12”.
Let us know if all looks good!
Best,
Noah Palker, E.I.
O'Leary-Burke Civil Associates, PLC
13 Corporate Drive
Essex Junction, VT 05452
email: npalker@olearyburke.com
phone: (802) 878-9990 | fax: (802) 878-9989
From: Monika Ingalls <moingalls@southburlingtonvt.gov>
Sent: Friday, July 26, 2024 12:17 PM
To: Bryan Currier <bcurrier@olearyburke.com>
Cc: Noah Palker <NPalker@olearyburke.com>
Subject: Re: EXTERNAL: Bolduc Subdivision #SD-24-11 - Storm Comments
Hi Bryan,
Thanks for sending. I have a few more comments below:
The gravel wetland should be sized to treat impervious proposed for the 1.97-acre lot. While this lot will not be constructed
at the same time, it is part of the same plan of development as the 6-acre and 16.44-acre lots and thus the 1.97-acre lot is
subject to Section 13.05 of the LDRs.
3
While I agree the storage difference between the proposed orifice and what is in the modeling is minimal, please use actual
inverts in the HydroCAD modeling to avoid confusion in the future.
On Sheet 4, Elev. E is called out at 360.57 in the gravel wetland detail, but is called out as 359.57 in the gravel wetland
schedule. Please revise.
Per Section 13.05.E.4.c., driveway culverts must have a minimum of 12" of cover. Please either lower the culvert invert or
raise the drive grade to achieve this cover.
Feel free to call if you want to discuss any of these items. Thank you for the opportunity to comment.
Have a great weekend,
Monika
Monika Ingalls
Stormwater Project Manager
Department of Public Works
City of South Burlington
104 Landfill Road
South Burlington, VT 05403
Office: (802) 658-7961 Ext. 6108
Cell: (802) 556-4996
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.
From: Bryan Currier <bcurrier@olearyburke.com>
Sent: 24 July 2024 11:20
To: Monika Ingalls <moingalls@southburlingtonvt.gov>
Cc: Noah Palker <NPalker@olearyburke.com>
Subject: RE: EXTERNAL: Bolduc Subdivision #SD-24-11 - Storm Comments
Hey Monika
See attached. Thanks. Let us know if you need anything else.
Thanks,
Bryan Currier, PE
O'Leary-Burke Civil Associates
13 Corporate Drive | Essex Jct., VT 05452
p: (802)878-9990
bcurrier@olearyburke.com
From: Monika Ingalls <moingalls@southburlingtonvt.gov>
Sent: Wednesday, July 24, 2024 10:19 AM
To: Bryan Currier <bcurrier@olearyburke.com>
Subject: Re: EXTERNAL: Bolduc Subdivision #SD-24-11 - Storm Comments
Hi Bryan,
4
I'm working on reviewing your responses to the Stormwater Utility comments. Could you forward the updated HydroCAD file for
review?
Thanks,
Monika
Monika Ingalls
Stormwater Project Manager
Department of Public Works
City of South Burlington
104 Landfill Road
South Burlington, VT 05403
Office: (802) 658-7961 Ext. 6108
Cell: (802) 556-4996
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.
From: Dave Wheeler <dwheeler@southburlingtonvt.gov>
Sent: 19 July 2024 14:30
To: Monika Ingalls <moingalls@southburlingtonvt.gov>
Cc: Marisa Rorabaugh <MRorabaugh@southburlingtonvt.gov>
Subject: FW: EXTERNAL: Bolduc Subdivision #SD-24-11 - Storm Comments
FYI
Cell (802) 556-4531
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.
From: Bryan Currier <bcurrier@olearyburke.com>
Sent: Friday, July 19, 2024 1:40 PM
To: Marla Keene <mkeene@southburlingtonvt.gov>; Dave Wheeler <dwheeler@southburlingtonvt.gov>
Cc: Bolduc, Vincent L. <vbolduc@smcvt.edu>; Noah Palker <NPalker@olearyburke.com>
Subject: EXTERNAL: Bolduc Subdivision #SD-24-11 - Storm Comments
This message has originated from an External Source. Please use proper judgment and caution when
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Good Afternoon Marla, David,
5
I am not sure who is doing the development review from the Stormwater Dept these days, so I included you both
on this email. If you could forward this email to the right person, I would appreciate it as we are a tight schedule to
be eligible for the August 6th DRB hearing. Please see the attached revised plans and responses to the comments
below. Let us know if you have any questions or concerns. Have a good weekend.
1. This project is located in the Muddy Brook watershed.
No response necessary.
2. As the project proposes to increase impervious onsite to more than one-half acre of
impervious surface, the project is subject to the requirements of section 13.05 of the
LDRs.
No response necessary.
3. The following application requirements listed in 13.05(C) are missing and should be
provided:
a. A plan showing the drainage area being captured by the proposed
stormwater treatment practice, as well as soil types/hydrologic soil groups
A drainage area and soil types for the proposed stormwater treatment practice along with soil types are
shown on Sheet 4 – Roadway & Storm Details. All soils are mapped HSG D, see attached USDA map.
b. A brief written description of the proposed stormwater treatment
Runoff from new impervious areas will be collected via grassed swales and routed to a gravel wetland
on the west side of the proposed shared driveway before being discharged to a delineated wetland.
4. The provided HydroCAD modelling does not include the 25-year storm. Please
provide this analysis in accordance with Section 13.05(C)(6) of the LDRs.
Please see the attached HydroCAD model showing the system can treat the 25-year storm in
accordance with Section 13.05(C)(6) of the LDRs.
5. The HydroCAD model shows stormwater exiting the gravel wetland through the 1-yr
orifice during the WQv storm, thus not meeting the WQv standard for extended
detention.
The HydroCAD model has been revised and stormwater no longer exits the 1-year orifice during the
WQv storm event.
6. The pipe invert out of the outlet structure of the gravel wetland is at 359.0. This
means that the permanent pool will be at 359.0 and that the wetland soil will be
entirely saturated. Is it possible to lower the invert of the pipe out of the outlet
structure?
For modelling purposes, the invert out for the outlet structure is set to the bottom of pond elevation, as
the storage volume within the wetland planting area is negligible. Please refer to Sheet 4 – Roadway &
Storm Details which specifies the permanent pool elevation is at 358.6’.
7. Per the Vermont Stormwater Management Manual, pretreatment swales with a
slope greater than 5% must utilize check dams. Please include a check dam at the
curve of the proposed drive, where the slope is greater than 5%.
A check dam has been added to the roadside swale where the slope is greater than 5%. The Vermont
Stormwater Management Manual requires check dams to be placed every 135’ within this > 5%
section. The length of this section is 230’ therefore one check dam should meet these requirements.
8. Please confirm the separation distance of each of the sewer/stormwater pipe
crossings.
The first crossing at the culvert has the invert of the culvert at an elevation of 360.5’ and the top of the
sewer pipe at 358.5’. The second crossing of the sewer service has the invert of the culvert at 359.7’
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and the top of the sewer service at 359.5’. My understanding is that 18” of separation must be
maintained for water and sewer crossings.
9. Is the proposed gravel wetland sized such that it will be capable of treating any
proposed impervious on Lot 1?
The gravel wetland is sized to treat the proposed impervious development for both the 16.44-acre lot
and the 6-acre lot to the South.
10. How will any residence constructed on Lot 1 connect to the access from Windswept
Ln? The site plan shows the proposed pretreatment swale running along the entirety
of the western portion of the proposed driveway. Will the pretreatment swale be
shortened when the home for Lot 1 is constructed?
The plan has been revised to show potential access to Lot 1. An additional yard drain has been added
to the pipe network. The yard drains will collect stormwater conveyed by the swales on each side of the
driveways. This will result in slightly decreasing the length of the swale which has been accounted for in
the HydroCAD model but is still within the 5-minute pretreatment standard.
11. What is the elevation of the proposed 12-ft drive over the 18” culvert?
The proposed drive elevation is 363.1’. Therefore, on the higher end of the culvert, the top will be at
362’, therefore, about 1 foot of cover is proposed. Please note that this is a private shared driveway.
12. It is recommended that the outlet of the proposed 18” culvert be altered such that it
does not discharge onto the adjacent lot. The current configuration would cause
runoff from approximately 5.5 acres of land to be channelized and discharged
directly onto the adjacent lot, which is likely to cause erosion.
The outflow for the 18” culvert has been altered slightly. The proposed grading has been adjusted to
contain outflow on the parcel and direct it towards the existing wetland. Additionally, rip-rap will be
added to the outflow to prevent erosion from the conveyed stormwater. See SH 5 – EPSC Plan.
13. Is any inlet protection proposed for the yard drain within the pretreatment swale?
The yard drains will be covered in filter fabric upon soil stabilization.
14. What will be the phasing of construction?
The road and utilities to the single-family home and ADU on the southern 6-acre lot will be constructed
first. The development on the 1.97-acre parcel lot will follow.
15. Will the proposed single-family home and ADU be guttered?
We expect the single-family home and ADU to be guttered or graded to route stormwater to the
pretreatment swale. Please see note added to Sheet 2 – Site Plan regarding rooftop runoff.
16. The DRB should include a condition requiring the applicant to regularly maintain all
stormwater treatment and conveyance infrastructure.
No response necessary.
Bryan Currier, PE
O'Leary-Burke Civil Associates
13 Corporate Drive | Essex Jct., VT 05452
p: (802)878-9990
bcurrier@olearyburke.com