20070327 Ver 1_More Info Received_20071126

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ARMSTRONG GLEN, P.C.
P.O. Box 7326
Charlotte, NC 28241
[phone]
FAX [phone]
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SIGNED

D7- o3a7
Engineering Report
WATER QUALITY MANAGEMENT
FOR
WACHOVIA WIERBRIDGE FINANCIAL CENTER
ASHEVILLE, NORTH CAROLINA
PREPARED FOR
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ARMSTRONG GLEN, P.C.
PO BOX 7326
CHARLOTTE, NORTH CAROLINA 28241
704-529-0345

Wachovia Weirbridge Financial Center
Asheville, North Carolina
TABLE OF CONTENTS
Introductory Letter, ..................................................................................................................1.
Site Location Map. .................................................................................................................... 3
Drainage Basin Delineation ................................................................................................... 4
Sand Filter Inspection and Maintenance Agreement
....5
Sand Filter Supplement ........................................................................................................... 9
Calculations 12
Required Items Check List ......................................................................................................15
Construction Drawing ..............................................................................................................17

.~.rmstro C~~en, ~. C.
PO Box 7326 9771-D Southern Pine Blvd. Phone [phone]
Charlotte, NC 28241 Charlotte, NC 28273 Fax [phone]
November 14, 2007
Annette Lucas
Stormwater and Wetland Coordinator
401 Oversight and Express Permits Unit
NC DENR Division of Water Quality
Wetlands and Storm Water Branch
512 North Salisbury Street
Raleigh, NC 27604
Re: Revisions to Existing Approved Storm Water Plan
Weirbridge Development
Asheville, North Carolina
Dear Ms. Lucas:
The following engineering report contains calculations, permit application forms, check list,
and construction drawings pertaining to the water quality BMP for a new Wachovia branch
in Asheville. Phase I of Weirbridge Village was originally permitted with individual
sediment ponds. The permanent development of the Wachovia site (Outlot #2) will be
constructed with underground detention and sedimentation sand filtration for water quality.
This report presents an underground combined sedimentation and sand filtration structure for
your consideration. All storm water that falls on the developed portion of Outlot #2 is
confined to the site by either grading or curbing. Runoff is guided along gutters, and into one
of one of five on-site catch basins. An underground storm pipe system carries storm water to
a splitter assembly (SB-4). The splitter guides the initial flow to the sedimentation filtration
structure SF-3. Flow goes through the sedimentation side of the structure, and spills through
weir slots over to the sand filtration side of SF-3. The filtered storm water is collected in an
outlet pipe, which exits the southerly end of SF-3. The filtered water flows through buried
pipe to junction box JB-10, and through buried pipe to a drop inlet to be provided by the
Weirbridge Village developer. After leaving the drop inlet, it is then discharged into the
bottom of a large tree well, where it flows by way of open channel to a culvert beneath the
Weirbridge Village entrance road.
The buried sedimentation/filtration system is simple and efficient, but routine maintenance is
required to prevent binding of the sand media and surcharging of the vault. Routine
maintenance will be carried out by Wachovia. An executed Inspection and Maintenance
Agreement is provided in this report. A recorded drainage easement is not needed since

maintenance is a Wachovia responsibility and the BMP is on Wachovia property. Access to
the Wachovia site is by way of a shopping center access road, which is open to the public.
We appreciate your consideration of our application for permit revision. Call me if you need
additional information.
Sincerely,
William H. Arms o , P.E., P.L.S.

SITE LOCA TION MAP

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Sand Filter Inspection and Maintenance Agreement
I will keep a maintenance record on this BMP. This maintenance record will be kept in a
log in a known set location. Any deficient BMP elements noted in the inspection will be
corrected, repaired or replaced immediately. These deficiencies can affect the integrity
of structures, safety of the public, and the removal efficiency of the BMP.
Important maintenance procedures;
- The drainage area will be carefully managed to reduce the sediment load to the
sand filter.
- Once a year, sand media will be skimmed.
- The sand filter media will be replaced whenever it fails to function properly after
vacuuming.
The sand filter will be inspected quarterly and within 24 hours after every storm event
greater than 1.0 inches (or 1.5 inches if in a Coastal County). Records of inspection and
rnaintenance will be kept in a known set location and will be available upon request.
Inspection activities shall be performed as follows. Any problems that are found shall
be repaired immediately.
BMP element: Potential roblem: How I will remediate the roblem:
The entire BMP Trash/debris is resent. Remove the trash debris.
The adjacent pavement Sediment is present on the Sweep or vacuum the sediment as
(if a Iicable) avement surface. soon as ossible.
The perimeter of the Areas of bare soil and/or Regrade the soil if necessary to
sand filter erosive gullies have formed. remove the gully, and then plant a
ground cover and water until it is
established. Provide lime and a
one-time fertilizer a lication.
Vegetation is too short or too Maintain vegetation at a height of
lon . a roximateI six inches.
The flow diversion The structure is clogged. Unclog the conveyance and dispose
structure of an sediment off-site.
The structure is damaged. Make any necessary repairs or
replace if damage is too large for
re air.
The pretreatment area Sediment has accumulated to Search for the source of the
a depth of greater than six sediment and remedy the problem if
inches. possible. Remove the sediment and
dispose of it in a location where it
will not cause impacts to streams or
the BMP.
Erosion has occurred. Provide additional erosion
protection such as reinforced turf
matting or riprap if needed to
revent future erosion roblems.
Weeds are resent. Remove the weeds, referabl b

hand. If a pesticide is used, wipe it
on the tiIants rather than spraying.

BMP element: Potential roblem: How I will remediate the roblem:
The filter bed and Water is ponding on the Check to see if the collector system
underdrain collection surface for more than 24 is clogged and flush if necessary. If
system hours after a storm. water still ponds, remove the top
few inches of filter bed media and
replace. If water still ponds, then
consult an ex ert.
The outflow spillway Shrubs or trees have started Remove shrubs and trees
and pipe to ow on the embankment. immediatel .
The outflow pipe is clogged. Provide additional erosion
protection such as reinforced turf
matting or riprap if needed to
revent future erosion roblems.
The outflow i e is dams ed. Re air or re lace the i
The receiving water Erosion or other signs of Contact the NC Division of Water
damage have occurred at the Quality 401 Oversight Unit at 919-
outlet. 733-1786.

I acknowledge and agree by my signature below that I am responsible for the
performance of the maintenance procedures listed above. I agree to notify DWQ of any
problems with the system or prior to any changes to the system or responsible party.
Print name: 1 L~-'01-'^ ~ `! a~ t ~
Title: 1 y E ('-~1~ ~ l 1~ t;-N '~
Address: 2>a ~ N ° ~~" ~' ° '~ ~' 1 `t- ~ ~ ~ ~~' 0 ~-
Note: The legally responsible party should not be a homeowners association unless more than 50% of
the lots have been sold and a resident of the subdivision has been named the president.
I, ~;Qj~~=,f- ~ ~~,,`)~,~~ , a Notary Public for the State of
.f~, ~v~~_y , County of ~~.~' ~ , do hereby certify that
personally appeared before me this i ~/
day of , ~, and acknowledge the due execution of the
forgoing wet detention basin maintenance requirements. Witness my hand and official
seal,
SEAL
My commission expires ~~ d ~~ ~ /~ ~ C.7~

Permit Number:
(to be provided by DWQ)
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STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
SAND FILTER SUPPLEMENT
This form must be filled out on fine, printed and submitted with all of the required information.
Make sure to also fill out and submit the Required Items Checklist (Section 111) and the I&M Agreement (Section IV)
L'PROJECT INFORMATION
Project name Wachovia - Wierbridge
Contact name William M. Armstrong
Phone number 704-529-0345
Date November 14, 2007
Drainage area number 1
II,' DESIGN INFORMATION.:
Site Characteristics
Drainage area (Ao) 32,970 fl2 OK
Impervious area 28,348 ft2
Impervious (IA) 86.0%
Design rainfall depth 1.0 in
Peak Flow Calculations
Does this project require prelpost control of the 1-yr 24-hr peak flow? N Y or N
1-yr, 24-hr runoff depth in
1-yr, 24-hr intensity inlhr
Pre-development 1-yr, 24-hr runoff ft3/sec
Post-development 1-yr, 24-hr runoff ft3/sec
Pre/Post 1-yr, 24-hr peak control ft3/sec
Storage Volume
Design volume 1,946 ft3
Adjusted water quality volume (WQVAdi) 1,460 fts
Volume contained in the sedimentation basin and on top of the sand filter. 1,492
Maximum head on the sedimentation basin and sand filter (hMaxFliter) 5.83 ft
Average head on the sedimentation basin and sand filter (hA) 2.92 ft
Runoff Coefficient (Rv) 0.82 (unitless)
Type of Sand Filter
Open sand filter? Y Y or N
If this is an open sand filter: The clearance between the bottom of the sand 20 ft
filter and the SHWT (dsHwr)
Closed/pre-cast sand filter? N Y or N
If this is a closed sand filter: The clearance between the bottom of the sand ft
filter and the SHWT (dSHWi)
If this is a closed, underground closed sand filter: The clearance between
the surface of the sand filter and the bottom of the roof of the underground ft
StrUCtUre (dSpace)
OK
OK
Form SW401-Sand Filter-Rev.1 Parts I and II. Project Design Summary, Page 1 of 3

Permit Number:
(to be provided 6y DWQ)
Sedimentation Basin
Surface area of sedimentation basin (As)
Sand Filter
Surface area of sand filter (Ar)
Depth of the sand media filter bed (dr)
Coefficient of permeability for the sand filter (k)
Time to drain the sand filter (t)
Time to drain the sand filter (t)
Additional Information
Does volume in excess of the design volume bypass the sand filter?
Is an off-line flow-splitting device used?
Does volume in excess of the design volume flow evenly distributed through a
vegetated filter?
What is the length of the vegetated filter?
Does the design use a level spreader to evenly distribute flow?
Is the BMP located at least 30ft from surface waters (50ft if SA waters)?
Is the BMP localed at least 100ft from water supply wells?
Are the vegetated side slopes equal to or less than 3:1
Is the BMP located in a recorded drainage easement with a recorded access
easement to a public Right of Way (ROW)?
What is the width of the sedimentation chamber/forebay (Wsed)?
What is the depth of sand over the outlet pipe?
Figure 1: Open Sand Filter
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128 ftZ OK
128 ft2 OK
1.5 ft
3.5 (ftlday)
40 hours OK
1.67 days
Y YorN
Y YorN OK
N Y or N Excess volume must pass through filter.
tt
YorN
Y YorN
Y YorN
Y YorN OK
Y Y or N OK
Oft OK
1.5 ft OK
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F3i~h ~~'at+~r Tal~te
Form SW401-Sand Filter-Rev.1 Parts I and II. Project Design Summary, Page 2 of 3

ARMSTRONG GLEN, P.C. X06 6,1~-cFlo~Q
P.O. Box 7326
Charlotte, NC 28241 PROJECT NO. Q ~Q -~ S SHEET NO. Z
Phone:[phone] CALCULATED BY ~1/YI ~DATE~I~_~~
Fax: [phone]
SCALE

ARMSTRONG GLEN, P.C.
P.O. Box 7326
Charlotte, NC 28241
Phone: [phone]
Fax: [phone]
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PROJECT NO. il ^ SHEET NO. D F 3
CALCULATED BY DATE
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Permit No.
(to be provided by DWQ)
III. REQUIRED ITEMS CHECKLIST
Please indicate the page or plan sheet numbers where the supporting documentation can be found. An incomplete submittal
package will result in a request for additional information. This will delay final review and approval of the project. Initial
in the space provided to indicate the following design requirements have been met. If the applicant has designated an agent, the
agent may initial below. If a requirement has not been met, attach justification.
Initials

Pagel Plan
Sheet No.

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1.~lans (1" - 50' or larger) of the entire site with labeled drainage area boundaries
System dimensions (length, width, and depth) for both the sedimentation chamber and the filter
chamber
Maintenance access,- Shl~~~~~j c~h~~ r Ph f r a~n C e G>!Y~'1r'Q
Flow splitting device, n
- Recorded drainage easement and public right of way (ROW),~r ~~< < 5 l B dG~.'~~ ~'CC~55PlX
- Design at ultimate build-out, ~{h.5 i 5 t t
- Off-site drainage (if applicable), and 110 ~ n
-Boundaries of drainage easement. 2r L ~ S~G~
2. Plan details (1" = 50' or larger) for the sand filter showing:
/System dimensions (length, width, and depth) for both the sedimentation chamber and the filter
chamber
intenance access,
'Flow splitting device,
- Recorded drainage easement and public right of way (ROW),
- Design at ultimate build-out,
- Off-site drainage (if applicable), and
-Boundaries of drainage easement.
3. Section view of the sand filter (1" = 20' or larger) showing:
- Depth(s) of the sedimentation chamber and sand filter chamber,
-Depth of sand filter media
-Connection between the sedimentation chamber and the sand filter chamber,
- SHWT level(s)
-Outlet pipe, and
-Clearance from the surface of the sand filter to the bottom of the roof of the underground structure (if
applicable)
L-^/YCIOSG= n 4. Supporting calculations (including drainage calculations)
~f C~OSC=L 5, Signed and notarized inspection and maintenance agreement
Form SW401-Sand Filter-Rev.1 Part III, Page 1 of 1