20081100 Ver 1_More Info Received_20081006

i Ward Consulting Engineers, P.C.
<? ?C Engineering Solutions for Civil Design,
<- Stormwater Management, and Stream/Wetland Restoration
September 30, 2008 D F3 1 1 0 l?
Y 0 CZ 6 2008
Ms. Sue Homewood, Division of Water Quality orE.NR-INAIER? ?e
Mr. Andrew Williams, Army Corps of Engineers VicU*°SAJAoS16R
Reference: Response to request for additional information for Section 401 Water Quality
Certification application and Section 404 of the Clean Water Act Application
Dear Ms. Homewood and Mr. Williams:
We have prepared the following responses to the additional data requested by your offices. Since
much of the information is the same we have compiled one response.
1. Avoidance and Minimization:
The stream channel was relocated within the children's garden to feed the existing
wetland on site that will be preserved. The construction of the parking facilities and
building will divert stormwater that was flowing to the wetland. The existing stream
bypasses the wetland to the east.
Crossings of the relocated channel were necessary for the park programming. The most
upstream culvert was minimized in length to accommodate two trails. The park designer
initially wanted to cross the stream with two pipes. The trails were combined over one
crossing in an effort to minimize impacts. The two trails are separate to maintain the flow
of perimeter traffic around the children's garden and to provide for an interior trail for the
children's garden visitors. A fence encloses the children's garden inside of the exterior
walkway.
The 42-inch pipe connecting the two wetland segments was shortened to 32 feet to
minimize its length of 70 feet shown on the first submittal. The retaining wall for the rain
garden was pulled to the north to accomplish this. The stream will be relocated for 27 feet
and tied into the existing channel just upstream of the existing wetlands. A severe head
cut exists in the channel at the location of the proposed 42-inch pipe. The proposed pipe
transitions the grade through this area a vertical depth of 3.33 feet.
The proposed wet pond is to be located in an area that existing ponding occurs. The
roadway for Florida Street provides an existing dam across the floodplain. Stormwater
flows currently enter and existing 24 inch pipe that connect two street catch basins and
then outlet to the south side of the street. The existing stream channel is confined between
two streets with piped systems. Aquatic habitat corridors are currently impacted both
upstream and downstream of the site. The pond will provide habitat for aquatic species
within the park site. A pond in any other location would have to be placed in the terrace
slope. The pond would not be able to be fed by the stream and would be too low to drain
8;38G Six Forks Road Suite tot, Raleigh NC 2,1615-5088 phone- yi9-8,7o-o1326
Fax: 919-87o-5359
to the existing street storm drainage system. A pond at this location and elevation would
not work with the programming of the park.
The Landscape Architect designing the park has additionally included a letter regarding
the avoidance and minimization issues.
2. Stream Restoration design for the Relocated Channel:
Reference reach data was collected on a segment of the project channel down stream of
Florida Street. The reference reach morphological data has been complied in the
morphological data sheet included with this submittal. The existing channel was surveyed
just upstream of the existing head cut within the area that will be relocated. Proposed
stream restoration design data was generated from the reference reach data and used to
layout the plan, profile and dimension of the relocated reach. This submittal includes
stream restoration data, profiles, and plan views.
Attached is an exhibit with the location shown for the proposed planting zone adjacent to
the stream. This area will be planted with native species of trees, shrubs, and grasses. A
list of typical species that may be used are as follows:
Betula nigra - River Birch
Plantanus occidentalis - Sycamore
Cornus alternifolia - Alternate leaf dogwood
Cornus amomum - Silky dogwood
Carpinus caroliniana - ironwood
Alnus serrulata - tag alder
Amelanchier arborea - serviceberry
Ilex verticillata - winterberry
Leucothoe axillaries - doghobble
Lindera benzoin - spicebush
Herbaceous species will include native species such as: Carex lupulina- hop sedge,
Juncus effuses- soft rush, Leersia oryzoides- rice cutgrass, Pancium virgatum -switch
grass.
The existing wetlands in the preservation area called the rain garden will be enhanced
with additional native species.
3. Compensatory mitigation: Compensatory mitigation is not required for this project. The
wetland impacts are under 0.1 of an Acre and the stream impacts are in compliance with
the nationwide permit.
4. Cross sections and profiles of stream culverts: A profile of the stream and culverts are
included in the submittal as well as a cross section of the 60-inch culvert. To obtain the
width and look of an arch the 60-inch pipe will be buried approximately 2 feet. The cross
section of the pipe shows the channel section within the 60-inch pipe. The proposed 42-
inch pipe will not be buried. The slope of the pipe is too steep for burial.
5. Temporary Impacts:
Temporary impacts may occur to the existing adjacent wetland during the installation of
HW-20. An anticipated temporary impact area at this location is approximately 130 feet.
Temporary impacts are anticipated to construct the boardwalk and retaining wall
downstream of HW-21. This impact area is anticipated to be approximately 375 feet.
The stream or wetlands will not be crossed by any construction equipment during
construction of the park at any other locations that shown permanent crossings. The park
is accessible from both Lee and Florida Streets on each side of the stream.
806 Sit Forks Roar] Suite iot, Raleigh N('27615-7,o88 Phone: t)t9-870-0,26
Fax: yit)-87o-7)3.59
Silt Fence will be placed upland of any wetland areas and will not cross any streams.
6. Dewatering Methods and Construction sequence:
The Upper channel will be completely constructed off line. The tie in below the 42-inch
RCP will be constructed with bypass pumping operations. After the relocated stream is
completed and stabilized the water will be turned into the new channel. A construction
sequence has been attached to this submittal.
7. Aqua-Swirl: I have included the technical data for the Aqua-Swirl that we have shown
on the pipe coming from the roadway median on Lee Street. This device is not proposed
for stormwater treatment for the project. The main goals of the device are to catch
sediment and debris from the roadway that is currently an issue with trash on the project
site. Sediment will still enter the stream from the project site area. Both the project site
and upstream watershed is stable and is well vegetated. The device is not anticipated to
have any effects on the stream regarding sediment transport. This intermittent stream
functions primarily during storm events.
8. Stormwater Management plan: A storm water management plan is being prepared for
the submittal to the state main office. Additionally one copy will be sent to Ms.
Homewood for review.
I hope that this response and additional data included with this letter satisfies your concerns
regarding this project. This project will be a valuable asset to the City of Greensboro and the
park users. Please let me know at your earliest convenience if you would like to discuss further
the information provided.
Sincerely,
Ward Consulting Engineers, P.C.

Becky L. Ward, P.E.
8:386 Six Forks Road Suite ioi, Raleigh NC ,27615 ,5o88 Phone: giq-870-07,26
Fax: [phone]
Arebilerlnre
Y/anuilig
CovmmnJly Design
DESIGN Interiors
September 29, 2008
Sue Homewood, Division of Water Quality
Andrew Williams, Army Corps of Engineers
... N..... .... ..N ......
. . . M .. N .. N . . N . . N .. . . N . N . N . M .... N . . N..
Dear Ms. Homewood and Mr. Williams,
The Gateway Gardens were conceived as the premier botanical garden in this part of the southeast. More than a
collection of plants, the park is intended to foster a sense of community and become a learning center for both
children and adults.
The project is comprised of several unique garden spaces: the Heritage Garden is a will showcase southern
plans ringing a large plaza and Gateway Icon fountain. The Heritage Garden and Great Lawn make up the
eastern portion of the gardens; the western portion is home to the Japanese Garden, Wedding Garden and the
White Oak Forest with a wide range of amenities such as boardwalks and treehouses to a Rose Garden and
brick-lined formal lawn. The heart of the Garden beats in the Children's Garden, where we hope to spark the
imagination of a new generation of gardeners and foster a sense of delight and wonder for the plant kingdom.
Our program called for extensive parking, which we reduced in favor of off-site event parking. In an effort to
further reduce ecological impacts, pervious pavement was added to the parking stalls in order to store rainwater
and allow gradual percolation into the soils below. The parking was sited in the northwest corner, where wisteria
had already choked out the existing trees, that allowed us to preserve a large stand of mature trees on the south
end, or the White Oak Forest, where the greatest environmental impact will be the sound of gleeful children.
Another key program element was the concern over road noise, which is why the Children's Garden was located
adjacent to busy Lee Street. The City of Greensboro wanted this active garden space in close association to the
Visitors' Center, which too is planned as an outdoor classroom. The theme of the Children's Garden is literacy:
attractions include an alphabet entry arbor, an alphabet soup bowl fountain, a whimsical potting shed and a book
stage where stories will be performed and told. We wanted to ensure the survival of a single, mature oak and
took advantage of its shade for the protection of small audiences nestled around the book stage. Part of that
effort went toward protecting a small wetland that is believed to nourish the oak tree. Great care was given to
designing a new stream channel that would reach the elevation of the wetland and keep these two natural
features connected and living. The stream channel serves as a natural separation between the intensely
developed fountain and maze area and the more structured uses planned for the book stage. The stream winds
its way through the garden and becomes part of the experience by showcasing the importance of water
protection-no other resource could be as meaningful in a garden.
• "• "' ' • " ' " ' • • • •• •• • • • • Designing real places.
125 North Harrington Street I Raleigh, NC 27603 1 t: 919-833-6413 1 f: 919-836-1280
272 North Front Street, Suite 500 1 Wilmington, NC 28401 1 t: 910-254-0222 1 f: 910-254-0228
1930 Camden Road, Suite 2010 1 Charlotte, NC 28203 1 t: 704-333-7272 1 f: 704-333-7278
www.clinedesignassoc.com
XI
2 of 2
This stream is altogether renewed. Rather than existing as a neglected by-product of road construction, the
enhanced channel weaves a sinuous path rich with indigenous plantings. Gone is the litter along with the
invasives. The stream becomes a significant and educational feature in the landscape: it is seen throughout
Gateway Gardens from its humble origin beneath Lee Street, through the Children's Garden and Rain Garden, to
eventually flow into the pond that separates the Promenade from the Japanese Garden. Throughout the design
process, crossings were minimized; the only piping that occurs on site was done only to maintain accessibility and
continuity of the walking surfaces leading into the Children's Garden. A broader, at-grade connection was needed
here to make the space not only accessible, but inviting. The grades from the building to the center of the
Children's Garden were held at 5% to reach existing grade quickly and with minimal intrusion on the site. Further
daylighting was added following initial DWQ comments, walls were relocated and another bridge added to the
design as a means of reducing impacts on the channel.
Relocation of the book stage was reviewed per recommendation. This, however, proved to be fruitless as the
client's program required the Book Stage to be integrated within the (fenced) boundaries of the Children's Garden.
When we looked at moving the walk and stage as a unit, the adjacent slopes became too steep to maintain both
soil and mulch between the parking lot and the walk below. The hillside is to be revegetated with a combination
of longleaf pine, oaks and maples and will provide a naturalized buffer between the parking and the gardens. The
same treatment has been afforded to the northwest of the parking lot, where the disturbed areas surrounding the
paved surfaces were reforested or naturalized. Wayfinding systems are planned to underscore the importance of
our water resources and will offer visitors the opportunity to follow the path through the various gardens up to the
culmination of the stream, albeit symbolically, into the pond.
Our clients felt strongly that the park needed a strong connection to water and were committed to showcasing
water-loving plants in the gardens. The design intent was to create a strong focal point and reflective space in
association with the meditative Japanese Garden and as a separation from the more public Great Lawn. The
pond was conceived to preserve water quality: an upper tier designed to flood is lined with plants to filter runoff
from adjacent walks and green spaces, whereas the main basin is filtered through the Rain Garden, which is a
large, unprogrammed tree preservation area. We chose to flood the stream channel beyond that point in order for
the basin to hold enough volume to avoid temperature fluctuations that might otherwise invite algae. This could
not have been possible with an off-line stream, which would have required an earthen barrier between to two
systems, nor could sufficient volume have been carved out as the grade rises quickly in the Japanese Garden;
the banks of the pond would have been too steep to maintain safely without fencing. While the pond is clearly
structured, it serves an important aesthetic purpose and fulfils a continuing, natural role in the on-site filtration
process.
In conclusion, the connection between land and water cannot be missed. Glimpses and "touches" are offered to
make the experience a hands-on learning adventure for children as well as a thought-provoking journey for adults.
Sincerely,
Lfj?Lp ?9
Eric W. Wolfe
Project Manager
• ~ 0 - • • N • N • • • • N .* • .N •
•••• 04017LCD03
PA04Proj104017\Land_Planning\3_Construction_Documents\LCD03_ConsuItant_Correspond ence\3.01_Civil\DWQ justification Letterhead
09292008.doc
i

Stream Restoration Plan and Data

I
Gateway Gardens
UT to South Buffalo Creek
Guilford County, NC
Variables Existing Channel Proposed Reach Reference Reach
Relocated Channel Below Florida St

Stream type .
E5-C5 C5 C5
Drainage Area
Acres) 13.26 8.68 19.05
Bankfull width 3.0 4
46
(Wbkf) feet riR-I 7M 3.75 .
,,, -, , „

Bankfull mean
0.40 J. / J--r.7V
0
21
depth (dbkf) feet (0.29-0.53 .
0'26
0.21-0.33}
Width/depth ratio 8.3 18
75
Wbkf/dbk 5-13 .
14.4 12.9-23.43
Bankfull Cross
Sectional Area 1.17
1
0 1.10
Abkf) (s ft) (0.96-1.42) ' (0.91-1.38)
Bankfull Mean
Velocity (Vbkf) 1.4 1.3 1.93
feet/second (1.33-2.43)
Bankfull Discharge, 2 08
cfs (Qb!SD cfs 1.58 1.26
1.47-2.34
Bankfull Maximum 0.60 0
45
depth dmax feet 0.44-0.75 0.40 .
0.37-0.56
Max driff/dbkf ratio 1.5 1
81

(1.4-1.5) 1.54 .
(1.71-1.90
Low Bank Height 0.64 0
34
feet 0.49-0.75 0'4 .
0.30-0.37
Ratio of Low bank 1.06 0
77
Height to max dbkf (1.0-1.11 1'0 .
0.63-0.85
Width of flood

prone area (Wfpa) 25 18
63.68
feet (6-45) (10-23) (44.20-86.38)
Entrenchment ratio 7.2 4.8 14.39
W a/Wbk 2.3-12.9 2.7-6.1 (10.47-18.51)
Meander length 27 25 30.5
Lm feet 17-34 24-29 28-35
Ratio of meander

length to bankfull 6.8
6.8
width Lm/Wbk (5.6-11.3) (6.3-7.8) (6.3-7.8)
Radius of Curvature 23
(Rc) feet 8.5
(5,25-95) 14
(10-18) (17-31)
1
Ratio of radius of
curvature to 2.8 3.6 3.61
bankfull width (1.75-31) (2.6-4.9) (2.67-4.86)
Rc/Wbk
Belt width (Wblt) 16 11
25
feet (14-18 12 .
(7-17)
Meander width ratio 5.3 2
64
Wblt/Wbk 4.7-6 3.2 .
1.65-4
Sinuosity (stream

length /valley
1.12
1.19 1.18

distance (k) 1.23 (VS/SS)
Valley slope (ft/ft)
0.0245 0.006 0.0227
Average slope Upper 0.0058

Sav = (Svalle / k
Lower 0.03 .0051 0.0185
Maximum pool 0.78 0
60
depth d ool feet 0.6-0.9 0'6 .
0.50-0.81
Ratio of pool depth

to average bankfull 1.95
2
3
2.43
depth (dpool/dbkf)
(1.5-2.25) .
(2.01-3.26)
Pool width (Wpool) 4.86 2
91
Feet 3.03-6.26 3.75
*3.75 .
2.3-3.43
Ratio of pool width 1
62 0.65
to bankfull width .
(1.01-2.08) 1.0 (0.52-0.77)
(W of/Wbkf)
Pool Cross
Sectional Area 2.26
1
3 1.02
s ft (1.71-3.22) . (0.73-1.70)
Ratio of pool area to 1.93 0
93
bankfull area (1.46-2.75 1.3 .
(0.67-1.55)
Pool to pool spacing 14 12 14.5
- feet 7-22 11-13.5 13-15.5
Ratio of p-p spacing

to bankfull width (p- 4.7 3.25 3.25

/Wbk (2.3-7.3
)
(3-3.6)
(3-3.6)
* Build pool same width as riffle and let narrow

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EROSION 3f1 DRWF 0.
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MATTING 1.2' 1,35' - 1,2,
AsT = 1.OFT2
V = 1,23 FT/SEC
Qc = 1.26 CFS
TYPICAL SECTION - RIFFLE S = 0,005 FT/FT
2
SCALE
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MATTING
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Aw = 1.3 FT2
V = 1.42 FT/SEC
Qc = 1.83 CFS
LIZP IAL S ECTION - POOL S 0,005 FT/FT
: NOT TO SCALE

Construction Sequence for Work in Existing and Relocated Channel:
1. Construct relocated channel from FES 19 to head of existing wetlands.
2. Install 60-inch Pipe and Headwalls
3. Install 42-inch RCP and Headwalls. Downstream headwall to be partially
constructed to maintain stream flow.
4. Bypass pump around work area from HW21 to existing wetlands.
5. Construct last 27 feet of relocated channel. Tie into existing channel.
6. Connect 30 inch RCP to existing DI-18 and divert flow into new channel.
7. Compete Construction of HW21 and Boardwalk/Bridge spanning relocated
stream and wetlands.
8. Bypass pump around normal flow as needed around work area in wet pond area as
new junction box and pond outlet structure are constructed.
9. Place pipe inlet protection on new drainpipe to maintain normal flow as needed.
10. Construct pond retaining walls.

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Project: Gateway Gardens
Date: 23-Sep-08
Prepared by: Zack Pitts
0 CP 757.34
1.74 HR 757.58
8.49 757.4
11.69 757.46
15.21 757.35
18.36 C P 757.26
23.26 HR 757.29
27.58 ER 757.28
32.68 CP 757.14
37.15 757.24
40.64 HR 757.3
44.32 ER 757.29
48.3 CP 757.1
51.96 HR 757.25
57.16 HR 757.35
62.35 757.31
64.92 ER 757.35
68.39 CP 756.91
71.86 HR 757.09
75.02 ER 756.95
77 CP 756.53
79.13 HR 756.85
83.56 ER 756.83
84.23 756.16
85.41 C P 755.8
89.99 HR 756.45
92.67 ER 756.52
94.72 CP 755.67
98.8 755.42
100.52 755.56
101.82 753.63
103.72 753.43
105.02 753.53
106.5 755.26
107.33 755.18
108.63 753.22
111.57 752.92
111.89 752.88
115.97 752.13
121.62 751.7
125.31 751.8
128.71 CONF 751.59
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Aqua-Swirl
1 . 1 . r
Aqua-Swirl T" Concentrator
Stormwater Treatment
Introduction
;t System Operation
Retrofit Applications
Installation
Buoyancy
Traffic Loading
Inspection and Maintenance
Aqua-Site Worksheet
Aqua-SwirlTM Sizing Chart
Aqua-Swirl TM Sample Detail
: Aqua-Swirl TM Specifications
a I I , i
¦ TM
AquaShleld
STO R M WATE R TREATMENT SOLUTION S
Table of Contents
AQUA-SWIRL TM
STORMWATER TREATMENT SOLUTIONS
System Operation
ru,+nm A-mi.--+ n?
%, x"141 nNJJuuauGna
Retrofit Applications
Installation
Buoyancy
Traffic Loading
Inspection and Maintenance
AnuinAita Wnrircheeft
Aqua-SwirlTM' Sizing Chart (English)
Aqua-SwirlTm Sizing Chart (Metric)
Aqua-SwirlTm Sample Detail Drawings
Aqua-SwirIT" Specifications
General
Scope of Work
Materials
Performance
Treatment of Chamber Construction
INSTALLATION
Excavation and Bedding
Backfill Requirements
Pipe Couplings
DIVISION OF RESPONSIBILITY
Stormwater Treatment System Manufacturer
Contractor
SUBMITTALS
QUALITY CONTROL INSPECTION
2733 Kanasita Drive, Suite B • Chattanooga, Tennessee 37343
Phone [phone] . Fax [phone]
www.aauashieldinc com
2
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A
4
5
5
6
6
7
8
9
13
15
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16
16
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r . . y
AquaShielci11" Stormwater Treatment SoliitiWIS
W Aqua-SwiriTM
14111111110",- Stormwater Treatment System
The patented Aqua-Swirl TM Storm water
Treatment System provides a highly effect
means for the removal of sediment,
floating debris, and free oil. Swirl
technology, or vortex separation, is a
proven form of treatment utilized in
the stormwater industry to accelerate
gravitational separation. Independent
university laboratory performance
evaluations have shown the Aqua-SwirITM
achieves a TSS (Total Suspended Solids)
removal of 91% calculated on a net
annual basis. See the "Performance and
Testing" Section for more details
Each Aqua-SwirITM is constructed of
lightweight and durable materials, eliminating the need for heavy lifting
eq iinment d rinn inctallatinn Tncnartinn anti Maintenanre are Marie A C11 With
...r....,... ' ..r............ , r and oversized risers that allow for both examination and cleanout without entering
the chamber.
0
W System Operation
The Aqua-SwirITM, with a conveyance flow diversion system, provides full
treatment for the most contaminated "first flush", while the cleaner peak storm
flow is diverted and channeled through the main conveyance pipe. Many
regulatory agencies are in the process of establishing "water quality treatment
flow rates" for specific areas based on the initial migration of pollutants into the
storm drainage system.
1)
. . ,
The treatment operation begins
when stormwater enters the
Aqua-SwirITM through a
tangential inlet pipe that
produces a circular (or vortex)
flow pattern that causes
contaminates to settle to the
base of the unit. Since
stormwater flow is intermittent
by nature, the Aqua-SwirITM
retains water between storm
events providing both "dynamic
and quiescent" settling of solids.
The dynamic settling occurs
during each storm event while Floatable debris in the Aqua-SwirITM'
the quiescent settling takes place
between successive storms. A combination of gravitational and hydrodynamic
drag forces encourages the solids to drop out of the flow and migrate to the
center of the chamber where velocities are the lowest, as shown from extensive
CFD modeling. See "Performance and Testing"for more
details
A large percentage of settleable
solids in stormwater are
reported to be small and
have low settling
velocities. low
Therefore,
the volume 4a *0
of water Outlet
retained in 4111100
the Aqua-SwirITM
provides the quiescent settling
that increases performance.
Furthermore, due to finer
sediment adhering onto larger
particles (less than 200
microns), the larger particles
settle, rather than staying
suspended in the water.
Inlet
3
AquaShield 11" St.Oi mwater Treatment Solutions
/ M . •
AcluaShield Ir" Storamater f reatment Soluti0FIS
The treated flow then exits the Aqua-Swirl'" behind the arched outer baffle. The
top of the baffle is sealed across the treatment channel, thereby eliminating
floatable pollutants from escaping the system. A vent pipe is extended up the
riser to expose the backside of the baffle to atmospheric conditions, preventing a
siphon from forming at the bottom of the baffle.
As recommended by the Center for Watershed Protection and several
municipalities, the Aqua-SwirITM can also operate in an offline configuration
providing full treatment of the "first flush." However, this orientation requires the
installation of additional manhole structures to di%iernA thin flow to thin Aqi ia-
SwirITM for treatment and conveyance back to the existing main conveyance
storm drainage system.
u Custom
lications
products to adapt to a variety of applications.
NO 'Tow Retrofit
ications
The Aqua-SwirITM system can
be modified to fit a variety of
purposes in the field, and the
angles for inlet and outlet lines
can be modified to fit most
applications. The photo on the
left demonstrates the flexibility
of Aqua-SwirITM installations.
Two Aqua-SwirITM units were
placed side by side in order to
treat a high volume of water
while occupying a small amount
of space. This configuration is
an example of the many ways
AquaShieldTM can use our
The Anua-SwirTMT'" system is designed so that it can easily be used for retrofit
applications. With the invert of the inlet and outlet pipe at the same elevation,
the Aqua-SwirITM can easily be connected directly to the existing storm
conveyance drainage system. Furthermore, because of the lightweight nature
and small footprint of the Aqua-SwirITM, existing infrastructure utilities (i.e.,
wires, poles, trees) would be unaffected by installation.
4
Custom designed AS-9 Twin, Aqua-SwirITM
. .1 4 1
AquaShield "'I Stormwater Treatment Solutions
ON
installation
The Aqua-SwirlTM system is designed and fabricated as a modular unit with no
moving parts so that no assembly is required on site. This facilitates an easy
installation of the system.
Since all AquaShieldTM systems are fabricated from
high performance materials, the Aqua-SwirlTM is
lightweight, and can be installed without the use of
heavy lifting equipment. Lifting supports or cables
are provided to allow easy offloading and
installation with a trackhoe. Compared to concrete
systems, using an Aqua-SwirlTM can significantly
reduce installation costs.
In addition, manufactured stub-outs for the inlet
and outlet are provided. This allows the contractor
to simply attach the Aqua-SwirlTm directly to the
main conveyance storm pipe with rubber couplings.
Typically, an AquaShieldTm representative is present
on-site to assist in the installation process.
Buoyancy
All Aqua-SwirlTM systems are supplied with an octagonal base plate that extends
a minimum of 6 inches beyond the outside diameter of the swirl chamber. The
function of the extension on this base plate is to provide additional surface area
to counter any buoyant force exerted on the system. The forces created on the
base plate by the weight of the surrounding fill material offsets the buoyant force
generated within the system. If needed, concrete can be poured directly onto the
base plate to provide additional resistive force. The AquaShieldTm engineering
staff can provide buoyancy calculations for your site-specific conditions.
5
The Aqua-Swirl'" Installed using
a trackhoe

A(I(.ia' Weld "" S>tounw?jter 1 reat?nE? it Solutio ris
When installed in traffic areas, the system will
be designed to withstand H-20 loading. In
order to accomplish this, a reinforced concrete
pad shall be poured in place above the
system.
See the "Installation and Fabrication " section
for sample concrete pad details and further
details on installation.
Concrete pad protects the Aqua-Swirly"
from impact loading
-W Inspection and Maintenance
Inspection and cleanout of the Aqua-Swirl T" is simple. The
chamber can be inspected and maintained completely
from the surface. Free-floating oil and floatable debris can
be directly observed and removed through the provided
service access.
Cleanout of accumulated solids is needed when the usable
storage volume has been occupied. The depth of solids
can easily be determined using a stadia rod or tape to
measure the top of the solids pile and calculate the
distance to the water's surface.
A vacuum truck can be used to remove the accumulated
sediment and debris. Disposal of the material is typically
treated in the same manner as catch basin cleanouts.
AquaShieldr"' recommends that all materials removed be
handled and disposed of in accordance with local and state
requirements.
For further details on inspection and cleanout procedures,
please see the "Maintenance "section.
6
Traffic Loading
sediment inspection
using a stadia rod
Vacuum truck cleans the
Aqua-Swirly"

AquaShieldl" Stornmater fieatment Solutions
N
:- Aqua-Site Worksheets
Aqua-Site worksheets are provided as an example of the information that
AquaShieldTM will need to customize an AquaSwirlTM to a specific work site.
• 1 completed example
• 2 blank worksheets
7

TIM . Inc.
2733 Kanasita Drive, Suit i Bd• Chattanooga, TN 37343
AquaShieldW"'
STORMWAfER TREATMENT SOLUTIO Phone: [phone] • Fax: [phone]
l. fllll www.AquaShieldInc.com
Aqua-Site Worksheet
Project Information
Project Name: count3; .7fospitar
Location (City, State): AnyTowry VSA
Site Use (circle one): Residential Commerical Industrial Other
Site Plan Attached: El YES NO
Pollutants (TSS, Floatable
Debris, oils/grease, TP, etc.): 7SS, Debris
AutoCAD version: 4.0
Date Submitted: 311212004
Specifier Information
Designer's Name: Sheri (Phifps
Design Firm: ('hips Engineering
Address: 123 main street
city, state, zip: AnyTowt4 VSA
Phone: [phone]
Fax: [phone]
E-mail: [e-mail]
Specifications

ilnii ibiini Design Flow Rate

--- -- Inlet/Outlet PIPe Rim
Elevation Drainage Area Info Traffic Loads
or Manhole
Number AquaShleldn'
Model Water Quality
Treatment
F1.4

(cfs - Us) Peak Design

Flow

(ds - Lis)
Size (ID)

(In - mm)
Invert
Elevation

(ft - m ) Pipe
Material

Type
Flnlsh Grade
Elevation

(ft - m)
Area

(acres - ha)
Incoming
Slope

(%)
Runoff
Coefficient

C Estimated
Groundwater

Elevation
(ft - m) Is the system
subject to H-20

loadings?
Yes a No
A-1 AS-6 5.3 15.9 18 736.2 WC(P 745.6 8.2 0.74 0.9 N/A Yes

Special Site Conditions or Requirements:

How did you learn
Please provide copy of Site Plans showing orientation
(1) Waf*r Anality Treatment Flnw k prncrlhod by Inral ronii4tnrv An?nriK M
achieve full treatment of specific amount of stormwater.
(2) Peak Design Flow refers to maximum calculated flow for an outfall or
recurrence Interval (10-yr, 25-yr event)
Specifler's Signature:
Date: 12-Mar-04

AquaShieldW .>w Aq S Suite B TM, inc.
2733 Kanasita Drive, uite B • Chattanooga, TN 37343
sTORMWATER TREATMENT SOLUTIONS Phone: [phone] • Fax: [phone]
` www.AquaShieldInc.com
Aqua-Site Worksheet
Project Information
Project Name:
Location (City, State):
Site Use (circle one): Residential Commerical Industrial Other
Site Plan Attached: YES NO
Pollutants (TSS, Floatable
Debris, oils/grease, TP, etc.):
AutoCAD Version: ----?-_---- --- -- -- -
Date Submitted:
Specifier Information
Designer's Name:
Design Finn:
Address:
City, State, Zip:
Phone:
Fax:
E-mail:
Specifications

1.111111 LAW Design Flow Rate Inlet/Outlet Pipe ElevItim ation Drainage Area info Traffic Loads
or Manhole

Number AquaShieldn'
Model Water Quality
Treatment
Flows

(crs - Us)
Peak De Ig
s n
Fl

(ds - Us)

SI2O (m)

(in - mm)
Invert
Elevation

(R-m)

Pipe
Material
Type

Flnlsh Elevation Grade

(ft-m)

Area

(ages - ha)

Incoming Slope

M

C Runoff
oefficient

C

Estimated
Groundwater
Elevation

(R - m)

Is the system
subject to H-20
loadings?

Yes or No

Special Site Conditions or Requirements:

How did you learn
about Aqua-Shield" ?
Please provide copy of Site Plans showing orientation
(1) Water Duality Treatment Flow is oresribed by local regulatory agencies to
achieve full treatment of specific amount of stormwater.
(2) Peak Design Flow refers to maximum calculated flow for an outfall or
recurrence Interval (10-yr, 25-yr event)
Specifier's Signature: Date:
f
r lot 4 y
AquaShieldW TM AquaShieldTM, inc.
2733 Kanasita Drive, Suite B • Chattanooga, TN 37343
STORMWATER TREATMENT SOLUTM Phone: [phone] • Fax: [phone]
? -, , l www.AquaShieldlnc.com
Aqua-Site Worksheet
Project Information Specifier Information
Project Name: Designer's Name:
Location (City, State): Design Finn:
Site Use (circle one): Residential Commerical Industrial Other Address:
Site Plan Attached: YES NO City, State, zip:
Pollutants (TSS, Ficatable
Debris, oils/grease, TP, etc.): Phone:
AutoCAD Version: Fax:
Date Submitted: E-mail:
Specifications

UARL La15ei Design Flow Rate In let/Outlet P ipe Rim
levatb Drainage Area Info
Traffic Loads
or Manhole
Number AquaShieldTM
Model Water Quality
Treatment
Flow'
(cfs - Us)
Peak Design
Fowl
(cis - Us)
Size (ID)

(in - mm)
Invert
Elevation
(ft • m) Pipe
Material
Type
Finish Grade
Elevation
(ft - m)

Area
(eves - ha)
Incoming
Slope

(%)
Runoff
Coefficient

C
Estimated
Groundwater
Elevation
(ft - m)
Is the system
subject to H-20
loadings?
Yes or No

Special Site Conditions or Requirements:

How did you learn
about Aqua-ShieldT"(?
Pi eas
e provide copy of S Plans showing orientation

(1) Water Quality Treatment Flow is presribed by local regulatory agencies to
achieve full treatment of specific amount of stornavater,
(2) Peak Design Flow refers to maximum calculated flow for an outfall or
recurrence Interval (10-yr, ZS-yr event)
Specitier's Signature: Date:

_,.I Aqua-SwirlTM Sizing Chart (English)
.,
Model

AS-2 Swirl
Chamber
Diameter Max
Stub-O
Outer D imum
ut Pipe
iameter Water Quality
Treatment
FloW2 Oil/Debris
Storage
Capacity Sediment
Storage
Capacity
2.50 8 12 1.1 37 10
AS-3 3.25 10 16 1.8 110 20
AS-4 4.25 12 18 3.2 190 32
AS-5 5.00 12 24 4.4 270 45
AS-6 6.00 14 30 6.3 390 65
AS-7 7.00 16 36 8.6 540 90
AS-8 8.00 18 42 11.2 710 115
AS-9 9.00 20 48 14.2 910 145
AS-10 10.0 22 54 17.5 1130 180
AS-12 12.0 24 48 25.2 1698 270
AS-XX Custom -- -- >26
Juno. water quaNty treatment now rates can be designed with multiple swills.
1) The Aqua-SwirlTm Conveyance Flow Diversion (CFD) provides full treatment of the
"first flush, " while the peak design storm is diverted and channeled through the main
conveyance pipe. Please refer to your local representative for more information.
2) Many regulatory agencies are establishing "water quality treatment flow rates" for their
areas based on the initial movement of pollutants into the storm drainage system. The
treatment flow rate of the Aqua-Swir1Tm system is engineered to meet or exceed the
local water quality treatment criteria. This "water quality treatment flow rate"
typically represents approximately 90% to 95% of the total annual runoff volume.
The design and orientation of the Aqua-FilterTm generally entails some degree of customization. For
assistance in design and specific sizing using historical rainfall data, please refer to an AquaShieldlm
representative or visit our website at www.AquaShieldlnc.com. CAD details and specifications are available
upon request.
tr . „
-.1111.1. Aqua-SwirlTMSizing Chart (Metric)
Aqua-SwirlTM
Model
AS-2 Swirl
Chamber
Diameter Max
Stub-O
Outer D
oaf Ine imum
ut Pipe
iameter
CFO ' Water Quality
Treatment
Fl OW2 Oil/Debris
Storage
Capacity
Storage
762
7 203 305 31 140 0.28
AS-3 991 254 406 51 416 0.57
AS-4 1295 305 457 91 719 0.91
AS-5 1524 305 610 125 1022 1.27
AS-6 1829 356 762 178 1476 1.84
AS-7 2134 406 914 243 2044 2.55
AS-8 2438 457 1067 317 2687 3.26
AS-9 2743 508 1219 402 3444 4.11
AS-10 3048 559 1372 495 4277 5.10
AS-12 3658 610 1219 713 6427 7.65
AS-XX Custom -- -- >713 -- --
..w.cr water quanty treatment now rates can be designed with multiple swirls.
1) The Aqua-Swir(Tm Conveyance Flow Diversion (CFD) provides full treatment of the
"first flush," while the peak design storm is diverted and channeled through the main
conveyance pipe. Please refer to your local representative for more information.
2) Many regulatory agencies are establishing "water quality treatment flow rates" for their
areas based on the initial movement of pollutants into the storm drainage system. The
treatment flow rate of the Aqua-Swid"m system is engineered to meet or exceed the local
water quality treatment criteria. This "water quality treatment flow rate" typically
represents approximately 90% to 95% of the total annual runoff volume.
The design and orientation of the Aqua-FilterT"" generally entails some degree of customization. For
assistance in design and specific sizing using historical rainfall data, please refer to an AquaShieldTm
representative or visit our website at www.AquaShieldlnc.com. CAD details and specifications are
available upon request.
? I
4 r4
AquaShield' Stormwater Treatment: Solutions
V
W Aqua-SwirlT" Sample Detail Drawings
Sample Aqua-SwirlTM detail drawings are provided as examples of the type of
systems that AquaShieldTM can offer for a specific work site.
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m

AquaShield"' 1tormwato Treatment SOILIOWIS
T Aqua-SwirlTM Specifications
GENERAL
This specification shall govern the performance, materials and fabrication
of the Stormwater Treatment System.
SCOPE OF WORK
The Aqua-SwirlTM shall be provided by AquaShieldT'", Inc., 2733 Kanasita
Drive, Chattanooga, TN (888-344-9044), and shall adhere to the following
material and performance specifications at the specified design flows and
storage capacities.
MATERIALS
A. Stormwater Treatment System shall be made from High-Density
Polyethylene (HDPE) resins meeting the following requirements:
1) HDPE Material - The HDPE material supplied under this
specification shall be high density, high molecular weight as
supplied by manufacturer. The HDPE material shall conform
to ASTM D3350-02 with rrninirruirn cell ciassii ication values of
345464C.
2) PHYSICAL PROPERTIES OF HDPE COMPOUND
a) Density - the density shall be no less than 0.955 g/cm3 as
referenced in. ASTM D 1505.
b) Melt Index - the melt index shall be no greater than 0.15
g/10 minutes when tested in accordance with ASTM D
1238- Condition 190/2.16.
c) Flex Modulus - flexural modulus shall be 110,000 to less
than 160,000 psi as referenced in ASTM D 790.
d) Tensile Strength at Yield - tensile strength shall be 3,000
to less than 3,500 psi as referenced in ASTM D 638.
e) Slow Crack Growth Resistance shall be greater than 100
hours (PENT Test) as referenced in ASTM F 1473 or
arAater than 5;000 hours (ESC R) as referenced in ASTM
D 1693 (condition Q.
15
,
AcluaShieJdl" St:orrrrwater f"reatment Solutions
f) Hydrostatic Design Basis shall be 1,600 psi at 23 degrees
t when tested in accordance with ASTM b 2837.
g) Color - black with minimum 2% carbon black.
B. REJECTION - The Stormwater Treatment System may be rejected
for failure to meet any of the requirements of this specification.
PERFORMANCE
A. The Stormwater Treatment System shall include a -inch inner
diameter (ID) circular hydrodynamic flow-through treatment
?iiaimiuer to ti eat ti ie ii iiuiiiii ig water-. A tai iyeiiLiai ii iet siiaii ue
provided to induce a swirling flow pattern that will cause
sedimentary solids to accumulate in the bottom center of the
chamber in such a way as to prevent re-suspension of captured
particles. An arched baffle wall shall be provided in such a way as
tv prevent fioaLa1iile liquid viii an u 0011U0 f vm Cnitilig thG t1 GQt niGnt
chamber while enhancing the swirling action of the stormwater.
B. The Stormwater Treatment System shall have a sediment storage
capacity of cubic feet and be capable of capturing gallons
of petroleum hydrocarbons. The Storm -if, r Treatment System
shall have a treatment capacity of cubic feet per second
(cfs). The Stormwater Treatment System shall be capable of
removing floating trash and debris, floatable oils and 80% of total
suspended solids from stormwater entering the treatment chamber.
C. Service access to the Stormwater Treatment System shall be
provided via 30-inch inner diameter (ID) access riser(s) over the
treatment chamber such that no confined space entry is required to
perform routine inspection and maintenance functions.
TREATMENT CHAMBER CONSTRUCTION
A. The treatment chamber shall be constructed from solid wall HDPE
ASTM F 714 cell class 345464C. For sizes above 63-inch OD, the
treatment chamber shall be constructed from profile wall HDPE
ASTM F 894 RSC 250 pipe or solid wall HDPE.
B. The bottom thickness of the treatment chamber will be determined
in accordance with ASTM F 1759. Calculations must be provided to
justify the thickness of the bottom.
16

AquaShieldIF" Stormwater Treatment Solutions
C. The inlets and outlets shall be extrusion welded on the inside and
outside of the structure using accepted welding methods.
D. The arched baffle wall shall be constructed from HDPE and shall be
extrusion welded to the interior of the treatment chamber using
accepted welding methods with connections made at 180 degrees
of each end.
E. HDPE lifting supports may be provided on the exterior of the
Stormwater Treatment System in such a way as to allow the
prevention of undue stress to critical components of the
Jwr mwater Treaty i lent Systern during loadii fig, 011 loaadii fig, as n d
moving operations. The lifting supports shall be constructed as an
integral part of the treatment chamber and extrusion welded using
accepted welding methods.
F. Tho ton of the treatment chamber shall be built to tha
r
requirements of the drawings. Deep burial applications shall require
a reinforced HDPE top.
Reinforced concrete pads spanning the treatment chamber will be
required with traffic rated frames and covers when the Stormwater
Treatment System is used in traffic areas. A professional engineer
shall approve the design of the concrete pad and the calculations
must be included in the submittal.
The manufacturer, upon request, can supply anti-flotation/
buoyancy calculations. In addition, typical drawings of the
AquaShieldTM Stormwater Treatment System with concrete anti-
flotation structures can also be provided. Anti-flotation structure
design and approval are ultimately the responsibility of the
specifying engineer. The contractor shall provide the anti-flotation
structures.
INSTALLATION
A. Excavation and Bedding
The trcnrh and trench hnitnm chill ha roncctnirterl in nrrnrrlanre
V.. VVbbV... V y.4vb?4 4?.\.V.44.. V.r
with ASTM D 2321, Section 6, Trench Excavation, and Section 7,
Installation. The Stormwater Treatment System shall be installed
on a stable base consisting of 12 inches of Class I stone materials
(angular, crushed stone or rock, crushed gravel; large void content,
cgntainino little or no fines) as defined by ASTM A 2321; SeCkian S;
Materials, and compacted to 95% proctor density.
17
a`
f
AqU-IS,hield"I Storniwatei- Fiecitnient_ Solutions
All required safety precautions for the Stormwater Treatment System
installation are the responsibility of the contractor.
B. Backfill Requirements
Backfill materials shall be Class I or II stone materials (well graded
gravels, gravelly sands; containing little or no fines) as defined by
ASTM D 2321, Section 5, Materials, and compacted to 90% proctor
density. Class I materials are preferred. Backfill and bedding
materials shall be free of debris. Backfilling shall conform to ASTM
F 1759, Section 4.2, "Design Assumptions." Backfill shall extend at
least 3.5 feet beyond the edge of the Stormwater Treatment System
for the full height to sub grade and extend laterally into
undisturbed soils.
C. Pipe Couplings
Pipe couplings to and from the Stormwater Treatment System shall
be Fernco®, Mission TM or an equal type flexible boot with stainless
steel tension bands. A metal sheer guard shall be used to protect
the flexible boot.
DIVISION OF RESPONSIBILITY
A. Stormwater treatment System Manufacturer
The manufacturer shall be responsible for delivering the
Stormwater Treatment System to the site. The system includes the
treatment chamber with debris baffle, inlet and outlet stub-outs,
lifting supports, 30-inch ID service access riser(s) to grade with
temporary cover(s), and manhole frame(s) and hover(s).
B. Contractor
The contractor shall be responsible for preparing the site for the
system installation including, but not limited to, temporary shoring,
excavation; cutting and removing pipe; new pipe; bedding; and
compaction. The contractor shall be responsible for furnishing the
means to lift the system components off the delivery trucks. The
contractor shall be responsible for providing any concrete anti-
floatation/anti-creep restraints, anchors, collars, etc. with any
straps or connection devices required. The contractor shall be
responsible for field cutting, if necessary, and HDPE service access
risers to grade. The contractor shall be responsible for sealing the
pipe connections to the Stormwater Treatment System, backfilling
and furnishing all labor, tools, and materials needed.
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AquaShield "^ Stonmater Freatment Solutions
SUBMITTALS
The contractor shall be provided with dimensional drawings; and when
specified, utilize these drawings as the basis for preparation of shop
drawings showing details for construction and reinforcing. Shop drawings
shall be annotated to indicate all materials to be used and all applicable
standards for materials, r'OgUired tests of materials, and design
assumptions for structural analysis. Shop drawings shall be prepared at a
scale of not less than 1/4 inch per foot. Three (3) hard copies of said shop
drawings shall be submitted to the specifying engineer for review and
approval.
QUALITY CONTROL INSPECTION
A. Materials
The quality of materials, the process of manufacturing, and the
finished sections shall be subject to inspection by the specifying
engineer. Such inspection may be made at the place of
construction, on the work site after delivery, or at both places. The
sections shall be subject to rejection at any time if material
conditions fail to meet any of the specification requirements, even
though sample sections may have been accepted as satisfactory at
the place of manufacture. Sections rejected after delivery to the
site shall be marked for identification and shall be removed from
the site at once. All sections, which are damaged beyond repair
after delivery will be rejected; and, if already installed, shall be
repaired to the specifying engineer's acceptance level, if permitted,
or removed and replaced entirely at the contractor's expense.
B. Inspection
All sections shall be inspected for general appearance, dimensions,
soundness, etc.
C. Defects
Structural defects may be repaired (subject to the acceptance of
the specifying engineer) after demonstration by the manufacturer
that strong and permanent repairs will be made. The specifying
engineer, before final acceptance of the components, shall carefully
inspect repairs.
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