HomeMy WebLinkAboutSP-18-57 - Supplemental - 1200 Airport Drive (13)1
Marla Keene
From:Dave Wheeler
Sent:Friday, January 4, 2019 5:37 PM
To:Marla Keene
Subject:Re: NOTEII Stormwater Narrative
Marla,
All my comments from Taxiway G have been addressed.
Thanks,
Dave
On Jan 4, 2019, at 3:26 PM, Gendron, Christopher <Chris.Gendron@stantec.com> wrote:
Hi Dave,
Below is a Narrative describing how the Taxiway ‘G’ stormwater treatment system meets the South
Burlington’s LDR’s. The table at the bottom summarizes the Impervious Areas and what is being
treated. If you have any questions or need any additional information please don’t hesitate to reach out.
Drainage Area #1
Stormwater Runoff from Drainage Area #1 discharges to a Pretreatment Swirl Separator then flows to
StormTrap #1 where the Water Quality Volume and the post-construction peak runoff rate for the one-
year, twenty-four hour rain event is infiltrated. Additionally the peak flows from the 10 and 100 year storm
events is detained and released at a rate less than pre-construction conditions. Flow is then directed to
S/N 001 and eventually to an unknown Tributary of the Winooski River.
Drainage Area #2
Stormwater Runoff from Drainage Area #2 directly discharges to discharge point S/N 001. It wasn’t
practical to capture all of the area being disturbed within this drainage area due to existing drainage
patterns, so some existing impervious area was treated within Drainage Area #1 to site balance these
untreated areas.
Drainage Area #3
Stormwater Runoff from Drainage Area #3 directly discharges to discharge point S/N 001. It wasn’t
practical to capture all of the area being disturbed within this drainage area due to existing drainage
patterns, so some existing impervious area was treated within Drainage Area #1 to site balance these
untreated areas.
Drainage Area #4
Stormwater Runoff from Drainage Area #4 includes a new 12’ perimeter road and reconstructing an
existing 12’ perimeter road. The perimeter road is sloped towards the airfield and the majority of it flows
over a minimum of 35’ of grassed area (disconnected) before being captured in an existing stormwater
system that discharges to discharge point S/N 001. Existing impervious area was treated within Drainage
Area #1 to site balance the untreated areas.
Drainage Area #5
Stormwater Runoff from Drainage Area #5 discharges to a Pretreatment Swirl Separator then flows to
StormTrap #2 where the Water Quality Volume and the post-construction peak runoff rate for the one-
year, twenty-four hour rain event is infiltrated.
Drainage Area Summary
2
Treated New or
Redeveloped
Impervious Area
(Acres)
Treated Existing
Area for Site
balancing (Acres)
Untreated New or
Redeveloped
Impervious Area
(Acres)
Treatment Type
Drainage Area #1 (to S/N
001)
25.846 2.217 0.000 Underground Infiltration
Chambers (StormTrap
#1)
Drainage Area #2 (to S/N
001)
0.000 0.000 0.756 N/A
Drainage Area #3 (to S/N
001)
0.000 0.000 1.206 N/A
Drainage Area #4 (to S/N
001)
0.849 0.000 0.155 Disconnection
TOTAL 26.695 2.217 2.117
Drainage Area #5 (to S/N
002)
1.629 1.185 0.000 Underground Infiltration
Chambers (StormTrap
#2)
Christopher Gendron, PE
Project Manager, Civil Engineering
Direct: 802 497-6402
Cell: 802 917-3117
Chris.Gendron@stantec.com
Stantec
55 Green Mountain Drive
South Burlington VT 05403-7824
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