HomeMy WebLinkAboutSD-20-40 - Supplemental - 0500 Old Farm Road (22)
P: (802) 878-0375 | email@krebsandlansing.com
Stormwater Collection, Treatment, & Detention System
Narrative
Hillside @ O'Brien Farm PHASE 2
Project Description
Phase 2 of the Hillside @ O’Brien Farm project involves a mixed use development
consisting of single family homes, duplexes, and industrial/commercial lots. The project
involves the re-routing of Old Farm Road, the extension of O’Brien Farm Road, and two new
City streets, Meadow Loop, and Legacy Farm Avenue. At this time, only subdivision of the
commercial and industrial lots is proposed. Additional site plans and stormwater designs will
be completed when the lots are developed.
Existing Condition
The west side of O’Brien Farm Road includes Phase 1 of the Hillside development, featuring
five City streets and 115 dwelling units in a combination of single family homes and
duplexes. Construction of Phase 1 is in progress and ongoing. Lots 11-15 permitted in Phase
1 for future development. Plan development and permitting is ongoing for a series of multi-
family apartment buildings on these lots. The land generally slopes east to west towards
Kennedy
The east side of O’Brien Farm features three permitted lots surrounding an existing
farmstead. There is a high spot adjacent to Old Farm Road that drains back towards the road.
The rest of the site drains west to east toward wetlands bisecting the property, and an
unnamed tributary of Potash Brook on the east side.
There are a variety of soil types on the property. On the west side of Old Farm Road,
development is mostly in soils identified as Farmingon-Stockbridge rocky loam (FsB) with
portions of Adams-Windsor loamy sands (AdA, AdB). The FsB soils are type “D” soils and
contribute to a high degree of runoff from the site. AdA and AdB soils are type “A” soils
and typically have low runoff potential. However, our experience on the site and on site soil
testing indicate a high water table, even in the “A” soils.
On the east side of Old Farm Road there are additional FsB and AdB soils, along with
Vergennes clay (VeC, VeB), Covington silty clay (Cv), and Farmington extremely rockly
loam (FaC). Smaller pockets of other soil types existing as well. The Farmington, Covington,
and Vergennes soils are all type “D”, indicating a high degree of runoff from the site.
Hillside @ O’Brien Farm
PHASE 2 Stormwater Narrative
August 16, 2020
PAGE [ 2 ]
Existing Stormwater System
The original Eldredge Street development received State of Vermont Stormwater discharge
Stormwater Permit #7815-INDS, which was obtained in September 2017 for Phase 1 of the
Hillside development. This permit also incorporated previously permitted infrastructure from
Stormwater discharge Permit #1-1520. Existing permitted stormwater infrastructure includes
Extended Detention Ponds 1, 2, and 3, Wet Ponds A and B, Infiltration Basin A, six grass
channels, and four infiltration trenches. Wet Pond B and the infiltration trenches have not
been constructed at this time. Wet Pond “B” and Wet Pond “C’, which was shown on the
plans but not permitted, are proposed to be converted to Gravel Wetlands #1 and #2 as part of
the Hillside Apartments project.
Proposed Stormwater System:
The proposed stormwater collection, treatment, and detention system will utilize a series of
gravel wetlands as the primary stormwater treatment practices. Based on prior experience,
we are assuming that even the areas of “A” soil on the site are unsuitable for infiltration
based practices due to high seasonal groundwater table. This will be verified with on-site soil
testing prior to completing our final designs. If favorable soil conditions are identified, one or
more of the gravel wetlands will be converted to infiltration based practices. We have
summarized the areas draining to each practice below:
Gravel wetland #3 treats impervious surface from the Meadow Loop road and
sidewalk, as well as all of the buildings, driveways, and walks for the Meadow Loop
units. Approximately 3.89 acres of impervious surface proposed to be treated.
Gravel wetland #4 treats impervious surface from the first 460 feet of Legacy Farm
Avenue, Legacy Farm extension, and the private driveway on Lot 35. It also treats
runoff from the buildings, driveways, and walks for the units along these sections of
road. Approximately 1.97 acres of impervious surface proposed to be treated.
Gravel wetland #5 treats impervious surface from Station 4+60 to 19+50 of Legacy
Farm Avenue. It also treats runoff from the buildings, driveways, and walks for the
units along these sections of road. Approximately 3.05 acres of impervious surface
proposed to be treated.
Gravel wetland #6 is located on an adjacent lot, Business Park North Lot 4, owned by
the applicant. This wetland will treat runoff from the relocated Old Farm Road, as
well as O’Brien Farm Road East, and Station 19+50 to 22+00 of Legacy Farm
Avenue. The gravel wetland will also treat the runoff from the roofs and driveways of
the units fronting these roads. Approximately 4.53 acres of impervious surface
proposed to be treated.
Gravel wetland #7 treats impervious surface from the first 900 feet of the proposed
Industrial/Commercial road. Future development on the industrial/commercial lots
will have additional stormwater treatment practices. Approximately 1.08 acres of
impervious surface proposed to be treated.
Gravel wetland #78 treats impervious surface from the last 280 feet of the proposed
Industrial/Commercial road. Future development on the industrial/commercial lots
Hillside @ O’Brien Farm
PHASE 2 Stormwater Narrative
August 16, 2020
PAGE [ 3 ]
will have additional stormwater treatment practices. Approximately 0.22 acres of
impervious surface proposed to be treated.
Gravel wetland #9 is shown on the westerly edge of Lot 17. This gravel wetland has
been “rough sized” to accommodate impervious surface from the C1-LR Lots 17, 22,
and portions of Lots 21 and 23.
At this time the applicant is proposing the use of pervious pavement in multiple
locations to reduce the amount of impervious surface on the site. These areas include:
o The proposed parking lot for the barn and event tent located east of Old Farm
Road.
o The proposed parking lot for the dog park and recreation facilities at the end
of O’Brien Farm Road East.
o All of the “cross-country” pedestrian trails and connections.
i) Description of Impervious Area: The proposed impervious surfaces include paved
roads and driveways, concrete walkways, paved recreation paths, roofs, and concret e
pads. A summary of the approximate area of impervious surface draining to each
watershed is above.
ii) Receiving Body:
(1) Wetlands in Potash Brook watershed.
(2) Unnamed tributaries of Potash Brook
iii) Fish Habitat Designation for Receiving Water:
http://www.anr.state.vt.us/dec/waterq/stormwater/docs/msgp/sw_water_quality_stand
ards.pdf)]
(1) Warm (both wetlands and tributaries of Potash Brook.
iv) Description of compliance with each of the 5 Unified Sizing Criteria in the 2017
VSMM Vol. I including the treatment practices or credits/waivers used to meet each
of the following standards:
(a) Water Quality Treatment Standard (WQv):
This standard will be met via the use of the gravel wetlands. All of the gravel
wetlands have been sized to contain 50% of the WQv in the voids of the
gravel. The remainder of the WQv will be provide in extended detention via a
low flow orifice in a controlled outlet structure.
(b) Groundwater Recharge Treatment Standard: The Groundwater Recharge
standard will be waived for the majority of the site due to the “D” soils. On
site soil testing will confirm whether the standard can be waived for the “A”
soils. If testing indicates adequate depth to groundwater, one or more of the
gravel wetlands will be converted to infiltration based practices to meet the
standard.
(c) Channel Protection Standard (CPv):
Hillside @ O’Brien Farm
PHASE 2 Stormwater Narrative
August 16, 2020
PAGE [ 4 ]
The Cpv standard is met by the use of Gravel Wetlands #3-9. The gravel
wetlands will feature additional storage capacity above the wetland and outlet
structures using low flow orifices to provide the required detention times.
(d) Overbank Flood Protection Standard (Qp10):
The Overbank Flood Protection Standard is met by the use Gravel Wetlands
#3-9. The gravel wetlands will feature additional storage capacity above the
wetland and controlled outlet devices to limit post development peak flows to
below pre development levels for the 10 year, 24 hour storm event.
(e) Extreme Flood Protection Standard (Qp100) :
The Extreme Flood Protection Standard is met by the is met by the use Gravel
Wetlands #3-9. The gravel wetlands will feature additional storage capacity
above the wetland and controlled outlet devices to limit post development
peak flows to below pre development levels for the 100 year, 24 hour storm
event.
Version: 1/29/2018 Project Name:Hillside @ OʹBrien Farm Phase2
Discharge Point:
Treatment Wetland #
Practice Drainage Area
For Permit
Coverage
Not for Permit
Coverage
Total to
Practice
1 Total Area (acres)5.920 0.000
5.920
2 3.890 0.000
3.890
3 0.000 0.000
0.000
WQV for
credit
WQV not for
credit
Total
WQV
4 WQV to practice 0.3164 0.0000 0.3164 96
5 2
6 2
Response Attachment location
7
8
9
10
11*
12*
13*
Response Attachment location
14 Forebay
↑Enter this value on the Standards
Compliance Workbook
Is outlet elevation designed such that a sub‐surface water level is maintained
in the gravel wetland?
If the gravel wetland is designed with an organic soil layer at the surface, have
vertical perforated riser pipes been provided to deliver stormwater
stormwater from the surface down to the gravel bed?
Have the outfalls and the conveyance to the discharge point been designed
and protected to avoid erosion?
Practice Type
Discharges to Cold or
Warm Water Fishery?
Modified CN for WQ
(1.0ʺ) storm
Note: Designers may use the Practice Drainage Area Runoff Calculator (second tab) for calculation of practice‐
specific runoff volumes for other treatment standards.
Conveyance (4.3.5.2)
Are inlets stabilized to ensure that non‐erosive conditions exist for at least the
1‐year, 24 hour storm?
* Questions preceded by an asterix (*) may change based on previously entered values
Have inlet pipes been set at the permanent pool or the base of the gravel bed?
New Impervious (acres)
4
3Treatment Wetlands (4.3.5)
Redeveloped Impervious
Has a low for orifice been provided to meet the the WQV and CPV extended
Has a liner designed in accordance with Section 4.3.5.2 been provided if the
infiltration rate exceed 0.05 inches per hour and the wetland is located above
Pre‐Treatment (4.3.6.3)
Has pretreatment been provided for non‐rooftop runoff?
Yes No
Yes No
No
No
Yes
Yes
NoYes
Cold
Warm
NoYes
NoYes
NoYes
Shallow surface wetland
Gravel wetland
Page 1 of 2
15
Response Attachment location
16 ft3 1378
17 ft3 6891
18 ft3 8269
19*
20*
21 60.0%Yes
22
23
Response Attachment location
24
25
26
27
28
29
Attachment location: Indicate the specific location (i.e. appendix, page, plan sheet) where the requisite support documentation has
been provided within the application.
What is the volume stored in the forebay or other volumetric pre‐
treatment if used? (minimum 10% WQV)
What is the volume stored in the permanent pool?
What is the total WQV stored at the normal water level (pre‐
treatment + permanent pool)?
Does the pre‐treatment volume plus the permanent pool equal at least 50% of
the WQV?
Has a planting plan been prepared showing how aquatic and terrestrial areas
will be stabilized, including plant species, plant locations, sources of plant
material and any required soil amendments?
Are any donor organic soils used in the practice obtained from a source other
than natural wetlands?
Is the remaining WQV provided for by extended detention over 24 hours?
Does the planting plan specify that no woody vegetation >2 inches in diameter
shall be planted or allowed to grow on the dam, within 15 feet of the dam or
the toe of the embankment, or within 25 of a principal spillway outlet?
What type of pretreatment is being
used?
Has an aquatic been been provided that extends at least 5 feet inward from the
normal water edge and is no more than 18 inches deep?
Has a setback been provided that extends 25 feet from the maximum design
water surface elevation of the practice?
Are all deep pool areas of ≥ 4 feet depth with side slopes steeper than 4:1 (H:V)
surrounded by a safety bench with ≤6% slope extending 10 feet outward from
the normal water edge to the toe of the side slope?
Landscaping (4.3.6.5)
Treatment (4.3.6.4)
Has a minimum flow path at normal water level of 3:1 been provided?
Swale
Filter Strip
Forebay (10% WQv)
Deep Sump Catch Basins
Proprietary
NoYes
NoYes
NoYes
Yes No
NoYes
NoYes
NoYes
NoYes
NoYes
NoYes
Page 2 of 2
Version: 1/29/2018 Project Name:Hillside @ OʹBrien Farm Phase2
Discharge Point:
Treatment Wetland #
Practice Drainage Area
For Permit
Coverage
Not for Permit
Coverage
Total to
Practice
1 Total Area (acres)4.240 0.000
4.240
2 1.970 0.000
1.970
3 0.000 0.000
WQV for
credit
WQV not for
credit
Total
WQV
4 WQV to practice 0.1654 0.0000 0.1654 93
5 2
6 2
Response Attachment location
7
8
9
10
11*
12*
13*
Response Attachment location
14 Forebay
New Impervious (acres)
6
4Treatment Wetlands (4.3.5)
Has a low for orifice been provided to meet the the WQV and CPV extended
Has a liner designed in accordance with Section 4.3.5.2 been provided if the
infiltration rate exceed 0.05 inches per hour and the wetland is located above
Redeveloped Impervious
Pre‐Treatment (4.3.6.3)
Has pretreatment been provided for non‐rooftop runoff?
Discharges to Cold or
Warm Water Fishery?
Modified CN for WQ
(1.0ʺ) storm
Note: Designers may use the Practice Drainage Area Runoff Calculator (second tab) for calculation of practice‐
specific runoff volumes for other treatment standards.
Conveyance (4.3.5.2)
Are inlets stabilized to ensure that non‐erosive conditions exist for at least the
1‐year, 24 hour storm?
* Questions preceded by an asterix (*) may change based on previously entered values
Have inlet pipes been set at the permanent pool or the base of the gravel bed?
↑Enter this value on the Standards
Compliance Workbook
Is outlet elevation designed such that a sub‐surface water level is maintained
in the gravel wetland?
If the gravel wetland is designed with an organic soil layer at the surface, have
vertical perforated riser pipes been provided to deliver stormwater
stormwater from the surface down to the gravel bed?
Have the outfalls and the conveyance to the discharge point been designed
and protected to avoid erosion?
Practice Type
Yes No
Yes No
No
No
Yes
Yes
NoYes
Cold
Warm
NoYes
NoYes
NoYes
Shallow surface wetland
Gravel wetland
Page 1 of 2
15
Response Attachment location
16 ft3 721
17 ft3 3602
18 ft3 4323
19*
20*
21 60.0%Yes
22
23
Response Attachment location
24
25
26
27
28
29
Does the planting plan specify that no woody vegetation >2 inches in diameter
shall be planted or allowed to grow on the dam, within 15 feet of the dam or
the toe of the embankment, or within 25 of a principal spillway outlet?
What type of pretreatment is being
used?
Has an aquatic been been provided that extends at least 5 feet inward from the
normal water edge and is no more than 18 inches deep?
Has a setback been provided that extends 25 feet from the maximum design
water surface elevation of the practice?
Are all deep pool areas of ≥ 4 feet depth with side slopes steeper than 4:1 (H:V)
surrounded by a safety bench with ≤6% slope extending 10 feet outward from
the normal water edge to the toe of the side slope?
Landscaping (4.3.6.5)
Treatment (4.3.6.4)
Has a minimum flow path at normal water level of 3:1 been provided?
Attachment location: Indicate the specific location (i.e. appendix, page, plan sheet) where the requisite support documentation has
been provided within the application.
What is the volume stored in the forebay or other volumetric pre‐
treatment if used? (minimum 10% WQV)
What is the volume stored in the permanent pool?
What is the total WQV stored at the normal water level (pre‐
treatment + permanent pool)?
Does the pre‐treatment volume plus the permanent pool equal at least 50% of
the WQV?
Has a planting plan been prepared showing how aquatic and terrestrial areas
will be stabilized, including plant species, plant locations, sources of plant
material and any required soil amendments?
Are any donor organic soils used in the practice obtained from a source other
than natural wetlands?
Is the remaining WQV provided for by extended detention over 24 hours?
Swale
Filter Strip
Forebay (10% WQv)
Deep Sump Catch Basins
Proprietary
NoYes
NoYes
NoYes
Yes No
NoYes
NoYes
NoYes
NoYes
NoYes
NoYes
Page 2 of 2
Version: 1/29/2018 Project Name:Hillside @ OʹBrien Farm Phase2
Discharge Point:
Treatment Wetland #
Practice Drainage Area
For Permit
Coverage
Not for Permit
Coverage
Total to
Practice
1 Total Area (acres)9.800 0.000
9.800
2 3.050 0.000
3.050
3 0.000 0.000
WQV for
credit
WQV not for
credit
Total
WQV
4 WQV to practice 0.2696 0.0000 0.2696 90
5 2
6 2
Response Attachment location
7
8
9
10
11*
12*
13*
Response Attachment location
14 Forebay
New Impervious (acres)
7
5Treatment Wetlands (4.3.5)
Has a low for orifice been provided to meet the the WQV and CPV extended
Has a liner designed in accordance with Section 4.3.5.2 been provided if the
infiltration rate exceed 0.05 inches per hour and the wetland is located above
Redeveloped Impervious
Pre‐Treatment (4.3.6.3)
Has pretreatment been provided for non‐rooftop runoff?
Discharges to Cold or
Warm Water Fishery?
Modified CN for WQ
(1.0ʺ) storm
Note: Designers may use the Practice Drainage Area Runoff Calculator (second tab) for calculation of practice‐
specific runoff volumes for other treatment standards.
Conveyance (4.3.5.2)
Are inlets stabilized to ensure that non‐erosive conditions exist for at least the
1‐year, 24 hour storm?
* Questions preceded by an asterix (*) may change based on previously entered values
Have inlet pipes been set at the permanent pool or the base of the gravel bed?
↑Enter this value on the Standards
Compliance Workbook
Is outlet elevation designed such that a sub‐surface water level is maintained
in the gravel wetland?
If the gravel wetland is designed with an organic soil layer at the surface, have
vertical perforated riser pipes been provided to deliver stormwater
stormwater from the surface down to the gravel bed?
Have the outfalls and the conveyance to the discharge point been designed
and protected to avoid erosion?
Practice Type
Yes No
Yes No
No
No
Yes
Yes
NoYes
Cold
Warm
NoYes
NoYes
NoYes
Shallow surface wetland
Gravel wetland
Page 1 of 2
15
Response Attachment location
16 ft3 1174
17 ft3 5871
18 ft3 7045
19*
20*
21 60.0%Yes
22
23
Response Attachment location
24
25
26
27
28
29
Does the planting plan specify that no woody vegetation >2 inches in diameter
shall be planted or allowed to grow on the dam, within 15 feet of the dam or
the toe of the embankment, or within 25 of a principal spillway outlet?
What type of pretreatment is being
used?
Has an aquatic been been provided that extends at least 5 feet inward from the
normal water edge and is no more than 18 inches deep?
Has a setback been provided that extends 25 feet from the maximum design
water surface elevation of the practice?
Are all deep pool areas of ≥ 4 feet depth with side slopes steeper than 4:1 (H:V)
surrounded by a safety bench with ≤6% slope extending 10 feet outward from
the normal water edge to the toe of the side slope?
Landscaping (4.3.6.5)
Treatment (4.3.6.4)
Has a minimum flow path at normal water level of 3:1 been provided?
Attachment location: Indicate the specific location (i.e. appendix, page, plan sheet) where the requisite support documentation has
been provided within the application.
What is the volume stored in the forebay or other volumetric pre‐
treatment if used? (minimum 10% WQV)
What is the volume stored in the permanent pool?
What is the total WQV stored at the normal water level (pre‐
treatment + permanent pool)?
Does the pre‐treatment volume plus the permanent pool equal at least 50% of
the WQV?
Has a planting plan been prepared showing how aquatic and terrestrial areas
will be stabilized, including plant species, plant locations, sources of plant
material and any required soil amendments?
Are any donor organic soils used in the practice obtained from a source other
than natural wetlands?
Is the remaining WQV provided for by extended detention over 24 hours?
Swale
Filter Strip
Forebay (10% WQv)
Deep Sump Catch Basins
Proprietary
NoYes
NoYes
NoYes
Yes No
NoYes
NoYes
NoYes
NoYes
NoYes
NoYes
Page 2 of 2
Version: 1/29/2018 Project Name:Hillside @ OʹBrien Farm Phase2
Discharge Point:
Treatment Wetland #
Practice Drainage Area
For Permit
Coverage
Not for Permit
Coverage
Total to
Practice
1 Total Area (acres)9.180 0.000
9.180
2 4.530 0.000
4.530
3 0.000 0.000
WQV for
credit
WQV not for
credit
Total
WQV
4 WQV to practice 0.3780 0.0000 0.3780 94
5 2
6 2
Response Attachment location
7
8
9
10
11*
12*
13*
Response Attachment location
14 Forebay
↑Enter this value on the Standards
Compliance Workbook
Is outlet elevation designed such that a sub‐surface water level is maintained
in the gravel wetland?
If the gravel wetland is designed with an organic soil layer at the surface, have
vertical perforated riser pipes been provided to deliver stormwater
stormwater from the surface down to the gravel bed?
Have the outfalls and the conveyance to the discharge point been designed
and protected to avoid erosion?
Practice Type
Discharges to Cold or
Warm Water Fishery?
Modified CN for WQ
(1.0ʺ) storm
Note: Designers may use the Practice Drainage Area Runoff Calculator (second tab) for calculation of practice‐
specific runoff volumes for other treatment standards.
Conveyance (4.3.5.2)
Are inlets stabilized to ensure that non‐erosive conditions exist for at least the
1‐year, 24 hour storm?
* Questions preceded by an asterix (*) may change based on previously entered values
Have inlet pipes been set at the permanent pool or the base of the gravel bed?
New Impervious (acres)
8
6Treatment Wetlands (4.3.5)
Redeveloped Impervious
Has a low for orifice been provided to meet the the WQV and CPV extended
Has a liner designed in accordance with Section 4.3.5.2 been provided if the
infiltration rate exceed 0.05 inches per hour and the wetland is located above
Pre‐Treatment (4.3.6.3)
Has pretreatment been provided for non‐rooftop runoff?
Yes No
Yes No
No
No
Yes
Yes
NoYes
Cold
Warm
NoYes
NoYes
NoYes
Shallow surface wetland
Gravel wetland
Page 1 of 2
15
Response Attachment location
16 ft3 1646
17 ft3 8232
18 ft3 9878
19*
20*
21 60.0%Yes
22
23
Response Attachment location
24
25
26
27
28
29
Attachment location: Indicate the specific location (i.e. appendix, page, plan sheet) where the requisite support documentation has
been provided within the application.
What is the volume stored in the forebay or other volumetric pre‐
treatment if used? (minimum 10% WQV)
What is the volume stored in the permanent pool?
What is the total WQV stored at the normal water level (pre‐
treatment + permanent pool)?
Does the pre‐treatment volume plus the permanent pool equal at least 50% of
the WQV?
Has a planting plan been prepared showing how aquatic and terrestrial areas
will be stabilized, including plant species, plant locations, sources of plant
material and any required soil amendments?
Are any donor organic soils used in the practice obtained from a source other
than natural wetlands?
Is the remaining WQV provided for by extended detention over 24 hours?
Does the planting plan specify that no woody vegetation >2 inches in diameter
shall be planted or allowed to grow on the dam, within 15 feet of the dam or
the toe of the embankment, or within 25 of a principal spillway outlet?
What type of pretreatment is being
used?
Has an aquatic been been provided that extends at least 5 feet inward from the
normal water edge and is no more than 18 inches deep?
Has a setback been provided that extends 25 feet from the maximum design
water surface elevation of the practice?
Are all deep pool areas of ≥ 4 feet depth with side slopes steeper than 4:1 (H:V)
surrounded by a safety bench with ≤6% slope extending 10 feet outward from
the normal water edge to the toe of the side slope?
Landscaping (4.3.6.5)
Treatment (4.3.6.4)
Has a minimum flow path at normal water level of 3:1 been provided?
Swale
Filter Strip
Forebay (10% WQv)
Deep Sump Catch Basins
Proprietary
NoYes
NoYes
NoYes
Yes No
NoYes
NoYes
NoYes
NoYes
NoYes
NoYes
Page 2 of 2
Version: 1/29/2018 Project Name:Hillside @ OʹBrien Farm Phase2
Discharge Point:
Treatment Wetland #
Practice Drainage Area
For Permit
Coverage
Not for Permit
Coverage
Total to
Practice
1 Total Area (acres)2.140 0.000
2.140
2 1.080 0.000
1.080
3 0.000 0.000
WQV for
credit
WQV not for
credit
Total
WQV
4 WQV to practice 0.0899 0.0000 0.0899 94
5 2
6 2
Response Attachment location
7
8
9
10
11*
12*
13*
Response Attachment location
14 Forebay
New Impervious (acres)
9
7Treatment Wetlands (4.3.5)
Has a low for orifice been provided to meet the the WQV and CPV extended
Has a liner designed in accordance with Section 4.3.5.2 been provided if the
infiltration rate exceed 0.05 inches per hour and the wetland is located above
Redeveloped Impervious
Pre‐Treatment (4.3.6.3)
Has pretreatment been provided for non‐rooftop runoff?
Discharges to Cold or
Warm Water Fishery?
Modified CN for WQ
(1.0ʺ) storm
Note: Designers may use the Practice Drainage Area Runoff Calculator (second tab) for calculation of practice‐
specific runoff volumes for other treatment standards.
Conveyance (4.3.5.2)
Are inlets stabilized to ensure that non‐erosive conditions exist for at least the
1‐year, 24 hour storm?
* Questions preceded by an asterix (*) may change based on previously entered values
Have inlet pipes been set at the permanent pool or the base of the gravel bed?
↑Enter this value on the Standards
Compliance Workbook
Is outlet elevation designed such that a sub‐surface water level is maintained
in the gravel wetland?
If the gravel wetland is designed with an organic soil layer at the surface, have
vertical perforated riser pipes been provided to deliver stormwater
stormwater from the surface down to the gravel bed?
Have the outfalls and the conveyance to the discharge point been designed
and protected to avoid erosion?
Practice Type
Yes No
Yes No
No
No
Yes
Yes
NoYes
Cold
Warm
NoYes
NoYes
NoYes
Shallow surface wetland
Gravel wetland
Page 1 of 2
15
Response Attachment location
16 ft3 392
17 ft3 1958
18 ft3 2350
19*
20*
21 60.0%Yes
22
23
Response Attachment location
24
25
26
27
28
29
Does the planting plan specify that no woody vegetation >2 inches in diameter
shall be planted or allowed to grow on the dam, within 15 feet of the dam or
the toe of the embankment, or within 25 of a principal spillway outlet?
What type of pretreatment is being
used?
Has an aquatic been been provided that extends at least 5 feet inward from the
normal water edge and is no more than 18 inches deep?
Has a setback been provided that extends 25 feet from the maximum design
water surface elevation of the practice?
Are all deep pool areas of ≥ 4 feet depth with side slopes steeper than 4:1 (H:V)
surrounded by a safety bench with ≤6% slope extending 10 feet outward from
the normal water edge to the toe of the side slope?
Landscaping (4.3.6.5)
Treatment (4.3.6.4)
Has a minimum flow path at normal water level of 3:1 been provided?
Attachment location: Indicate the specific location (i.e. appendix, page, plan sheet) where the requisite support documentation has
been provided within the application.
What is the volume stored in the forebay or other volumetric pre‐
treatment if used? (minimum 10% WQV)
What is the volume stored in the permanent pool?
What is the total WQV stored at the normal water level (pre‐
treatment + permanent pool)?
Does the pre‐treatment volume plus the permanent pool equal at least 50% of
the WQV?
Has a planting plan been prepared showing how aquatic and terrestrial areas
will be stabilized, including plant species, plant locations, sources of plant
material and any required soil amendments?
Are any donor organic soils used in the practice obtained from a source other
than natural wetlands?
Is the remaining WQV provided for by extended detention over 24 hours?
Swale
Filter Strip
Forebay (10% WQv)
Deep Sump Catch Basins
Proprietary
NoYes
NoYes
NoYes
Yes No
NoYes
NoYes
NoYes
NoYes
NoYes
NoYes
Page 2 of 2
Version: 1/29/2018 Project Name:Hillside @ OʹBrien Farm Phase2
Discharge Point:
Treatment Wetland #
Practice Drainage Area
For Permit
Coverage
Not for Permit
Coverage
Total to
Practice
1 Total Area (acres)0.450 0.000
0.450
2 0.220 0.000
0.220
3 0.000 0.000
WQV for
credit
WQV not for
credit
Total
WQV
4 WQV to practice 0.0184 0.0000 0.0184 94
5 2
6 2
Response Attachment location
7
8
9
10
11*
12*
13*
Response Attachment location
14 Forebay
↑Enter this value on the Standards
Compliance Workbook
Is outlet elevation designed such that a sub‐surface water level is maintained
in the gravel wetland?
If the gravel wetland is designed with an organic soil layer at the surface, have
vertical perforated riser pipes been provided to deliver stormwater
stormwater from the surface down to the gravel bed?
Have the outfalls and the conveyance to the discharge point been designed
and protected to avoid erosion?
Practice Type
Discharges to Cold or
Warm Water Fishery?
Modified CN for WQ
(1.0ʺ) storm
Note: Designers may use the Practice Drainage Area Runoff Calculator (second tab) for calculation of practice‐
specific runoff volumes for other treatment standards.
Conveyance (4.3.5.2)
Are inlets stabilized to ensure that non‐erosive conditions exist for at least the
1‐year, 24 hour storm?
* Questions preceded by an asterix (*) may change based on previously entered values
Have inlet pipes been set at the permanent pool or the base of the gravel bed?
New Impervious (acres)
6
8Treatment Wetlands (4.3.5)
Redeveloped Impervious
Has a low for orifice been provided to meet the the WQV and CPV extended
Has a liner designed in accordance with Section 4.3.5.2 been provided if the
infiltration rate exceed 0.05 inches per hour and the wetland is located above
Pre‐Treatment (4.3.6.3)
Has pretreatment been provided for non‐rooftop runoff?
Yes No
Yes No
No
No
Yes
Yes
NoYes
Cold
Warm
NoYes
NoYes
NoYes
Shallow surface wetland
Gravel wetland
Page 1 of 2
15
Response Attachment location
16 ft3 81
17 ft3 401
18 ft3 482
19*
20*
21 60.2%Yes
22
23
Response Attachment location
24
25
26
27
28
29
Attachment location: Indicate the specific location (i.e. appendix, page, plan sheet) where the requisite support documentation has
been provided within the application.
What is the volume stored in the forebay or other volumetric pre‐
treatment if used? (minimum 10% WQV)
What is the volume stored in the permanent pool?
What is the total WQV stored at the normal water level (pre‐
treatment + permanent pool)?
Does the pre‐treatment volume plus the permanent pool equal at least 50% of
the WQV?
Has a planting plan been prepared showing how aquatic and terrestrial areas
will be stabilized, including plant species, plant locations, sources of plant
material and any required soil amendments?
Are any donor organic soils used in the practice obtained from a source other
than natural wetlands?
Is the remaining WQV provided for by extended detention over 24 hours?
Does the planting plan specify that no woody vegetation >2 inches in diameter
shall be planted or allowed to grow on the dam, within 15 feet of the dam or
the toe of the embankment, or within 25 of a principal spillway outlet?
What type of pretreatment is being
used?
Has an aquatic been been provided that extends at least 5 feet inward from the
normal water edge and is no more than 18 inches deep?
Has a setback been provided that extends 25 feet from the maximum design
water surface elevation of the practice?
Are all deep pool areas of ≥ 4 feet depth with side slopes steeper than 4:1 (H:V)
surrounded by a safety bench with ≤6% slope extending 10 feet outward from
the normal water edge to the toe of the side slope?
Landscaping (4.3.6.5)
Treatment (4.3.6.4)
Has a minimum flow path at normal water level of 3:1 been provided?
Swale
Filter Strip
Forebay (10% WQv)
Deep Sump Catch Basins
Proprietary
NoYes
NoYes
NoYes
Yes No
NoYes
NoYes
NoYes
NoYes
NoYes
NoYes
Page 2 of 2
Version: 1/29/2018 Project Name:
Discharge Point:
Treatment Wetland #
Practice Drainage Area
For Permit
Coverage
Not for Permit
Coverage
Total to
Practice
1 Total Area (acres)3.750 0.000
3.750
2 2.430 0.000
2.430
3 0.000 0.000
0.000
WQV for
credit
WQV not for
credit
Total
WQV
4 WQV to practice 0.1979 0.0000 0.1979 96
5 2
6 2
Response Attachment location
7
8
9
10
11*
12*
13*
Response Attachment location
14 Forebay
↑Enter this value on the Standards
Compliance Workbook
Is outlet elevation designed such that a sub‐surface water level is maintained
in the gravel wetland?
If the gravel wetland is designed with an organic soil layer at the surface, have
vertical perforated riser pipes been provided to deliver stormwater
stormwater from the surface down to the gravel bed?
Have the outfalls and the conveyance to the discharge point been designed
and protected to avoid erosion?
Practice Type
Redeveloped Impervious
Pre‐Treatment (4.3.6.3)
Has pretreatment been provided for non‐rooftop runoff?
Discharges to Cold or
Warm Water Fishery?
Modified CN for WQ
(1.0ʺ) storm
Note: Designers may use the Practice Drainage Area Runoff Calculator (second tab) for calculation of practice‐
specific runoff volumes for other treatment standards.
Conveyance (4.3.5.2)
Are inlets stabilized to ensure that non‐erosive conditions exist for at least the
1‐year, 24 hour storm?
* Questions preceded by an asterix (*) may change based on previously entered values
Have inlet pipes been set at the permanent pool or the base of the gravel bed?
New Impervious (acres)
Hillside @ OʹBrien Farm Phase2
4
9Treatment Wetlands (4.3.5)
Has a low for orifice been provided to meet the the WQV and CPV extended
Has a liner designed in accordance with Section 4.3.5.2 been provided if the
infiltration rate exceed 0.05 inches per hour and the wetland is located above
Yes No
Yes No
No
No
Yes
Yes
NoYes
Cold
Warm
NoYes
NoYes
NoYes
Shallow surface wetland
Gravel wetland
Page 1 of 2
15
Response Attachment location
16 ft3 862
17 ft3 4310
18 ft3 5172
19*
20*
21 60.0%Yes
22
23
Response Attachment location
24
25
26
27
28
29
Attachment location: Indicate the specific location (i.e. appendix, page, plan sheet) where the requisite support documentation has
been provided within the application.
What is the volume stored in the forebay or other volumetric pre‐
treatment if used? (minimum 10% WQV)
What is the volume stored in the permanent pool?
What is the total WQV stored at the normal water level (pre‐
treatment + permanent pool)?
Does the pre‐treatment volume plus the permanent pool equal at least 50% of
the WQV?
Has a planting plan been prepared showing how aquatic and terrestrial areas
will be stabilized, including plant species, plant locations, sources of plant
material and any required soil amendments?
Are any donor organic soils used in the practice obtained from a source other
than natural wetlands?
Is the remaining WQV provided for by extended detention over 24 hours?
Are all deep pool areas of ≥ 4 feet depth with side slopes steeper than 4:1 (H:V)
surrounded by a safety bench with ≤6% slope extending 10 feet outward from
the normal water edge to the toe of the side slope?
Landscaping (4.3.6.5)
Treatment (4.3.6.4)
Has a minimum flow path at normal water level of 3:1 been provided?
Does the planting plan specify that no woody vegetation >2 inches in diameter
shall be planted or allowed to grow on the dam, within 15 feet of the dam or
the toe of the embankment, or within 25 of a principal spillway outlet?
What type of pretreatment is being
used?
Has an aquatic been been provided that extends at least 5 feet inward from the
normal water edge and is no more than 18 inches deep?
Has a setback been provided that extends 25 feet from the maximum design
water surface elevation of the practice?
Swale
Filter Strip
Forebay (10% WQv)
Deep Sump Catch Basins
Proprietary
NoYes
NoYes
NoYes
Yes No
NoYes
NoYes
NoYes
NoYes
NoYes
NoYes
Page 2 of 2