HomeMy WebLinkAboutSP-18-57 - Supplemental - 1200 Airport Drive (14)1
Marla Keene
From:Gendron, Christopher <Chris.Gendron@stantec.com>
Sent:Friday, January 4, 2019 3:27 PM
To:Dave Wheeler
Cc:Marla Keene; Leinwohl, Jon
Subject:NOTEII Stormwater Narrative
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
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
2
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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