20061651 Ver 1_More Info Received_20070123

Environmental Consultants, PA
Road Raleigh, North Carolina 27614 Phone: [phone] Fax: [phone]
Transmittal
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Charlotte Office: Y'R"'"'"- Greensboro Office:
236 LePhillip Court, Suite C 3817-E Lawndale Drive
Concord, NC 28025 Greensboro, NC 27455
Phone: [phone] Phone: [phone]
Fax: [phone] Fax: [phone]
We Transmit to you Herewith: Under Separate Cover:
^ Drawings ® For your information and files ~ By mail
^ Specifications ^ For comment or approval By courier
Brochures or photos ^ Returned for correction, resubmit ^ By express
Corres ondence A roved as noted

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• Soil & Environmental Consultants, PA
11010 Raven Ridge Road Raleigh, North Carolina 27614 Phone: [phone] Fax: [phone]
www.SandEC.com
January 22, 2007
S&EC Project #9654.W2
DWQ Project #06-1651
Department of Environment and Natural Resources
Division of Water Quality
Attn: Cyndi Karoly
2321 Crabtree Boulevard, Suite 250
Raleigh, NC 27604
Re: Reply to the Division of Water Quality's Request for More Information
West Chatham Townhomes
Cary, Wake County, NC
To Whom It May Concern:
The purpose of this letter is to respond to your Request for More Information letter dated December 4,
2006. The original questions/requests are copied below as they appear within letter and are then followed
by our response.
Additional Information Requested:
1. Your constructed wetland stormwater BMP design is 15 percent too small as proposed. Please re-
design your constructed wetland so that it is appropriately sized and submit your new plans and
worksheet. Additionally, your Operations and Maintenance agreement is inadequate. Please contact
Cynthia Van Der Wiele at 919-715-3473 to discuss the Operations and Maintenance agreement for
this project.
After discussions with Annette Lucas of the 401/Express Review Unit, the proposed stormwater
BMP design, DWQ worksheet and Operations & Maintenance Agreement have been revised.
Attached is the original and 4 copies of the signed and notarized revised Operations and
Maintenance Agreement, 5 copies of the revised DWQ-401 Extended Detention Wetland Worksheet
and 5 copies of sheet C3.3, the revised constructed wetland detail for the West Chatham
Townhomes.
We anticipate that this answers all of the DWQ's questions in order to complete the final review process
fora 401 Water Quality Certification. If you have any further questions or any additional explanation is
needed, please don't hesitate to call.
Sincerely,
Debbie Edwards
Environmental Specialist
CC:
Matthew Danielson-Beazer Homes, 5811 Glenwood Ave, Suite 200, Raleigh, NC 27612
Travis Crissman-BNK, 6310 Chapel Hill Road, Suite250, Raleigh, NC 27607
Attachments:
1) Signed and notarized Operations & Maintenance Agreement (5 copies)
2) DWQ-401 Extended Detention Wetland Worksheet (5 copies)
3) Sheet C3.3-Constructed wetland detail (5 copies)
Charlotte Office: Greensboro Office:
236 LePhillip Court, Suite C 3817-E Law dale Drive
Concord, NC 28025 Greensboro,~C 27455
Phone: [phone] Phone: [phone]
Fax: [phone] Fax: [phone]

OPERATION AND MAINTENANCE PLAN
FOR
EXTENDED DETENTION STORM WATER WETLAND
This is the proposed Operation and Maintenance (O&M) Plan for the extended detention
storm water wetland at West Chatham Townhomes in Cary, NC.
1. Inspection Frequency
The treatment device and its structural components, to include the sediment forebays,
shall be inspected after every significant runoff producing rainfall event (roughly 0.5
inches of rainfall) and at least semi-annually. Inspections shall be performed by persons
of sufficient background and understanding of the structure and its intended purpose.
2. General Inspection
General inspection activities for the Extended Detention Storm Water Wetland shall
include:
a. Inspection for trash accumulation, vegetative cover including wetland plant
species, and general condition. Litter and debris shall be removed from wetland,
sediment forebays, riser trash rack and the riser drawdown orifice.
b. Check and clear drawdown orifice of any obstructions such that the drawdown of
the temporary pool occurs as intended by the design.
c. Inspect contributing storm water collection system (ie. piping, swales, riprap, etc.)
for condition and proper function.
d. Inspect sediment forebays and storm water wetland for sediment accumulations at
a minimum of every six months and after each runoff producing rainfall event.
The depth of sediment within the forebays and wetland shall be measured during
each inspection.
3. Structural Inspection
Structural inspections of the Extended Detention Storm Water Wetland shall include the
following:
a. Inspect for erosion at the forebay inlet stabilization and outflow weir, and outlet
protection apron (at flared-end sections and natural channel inlets). Identify any
deficiencies with the installed method of stabilization to include displacement of
riprap or geotextile fabric.
b. Inspect the sediment forebay and weir for function and condition (including depth
of sediment).
Page 1 of 4

c. Inspect for erosion along the wetland perimeter. Inspect perimeter slopes for
cracking or settling, slope stability, ground cover, the presence of undesirable or
nuisance vegetation.
d. Inspect wetland spillway structures, including but not limited to, the riser, trash
rack, barrel, outlet flared-end section, drawdown orifice, and low-level outlet for
general condition, deterioration, and proper operation. Inspect structure for
evidence of cracks or leakage in structure. Maintenance (low-level) outlet valve
shall be checked for complete function during each inspection. The valve shall be
moved to the full open position for a brief period during each inspection.
4. Maintenance and Repairs
Maintenance and repair activities shall include:
Repair eroded areas to include embankment or perimeter slopes immediately,
reseed as necessary to maintain good vegetative cover. Mow embankment cover
to maintain maximum height of six inches, remove unwanted woody vegetation as
needed.
b. Make repairs to contributing storm water collection system to maintain proper
function.
c. Remove accumulated sediment and debris from wetlands and basin as required
described below:
Forebays -Sediment within the forebay shall be removed when the depth
of sediment reaches one-half of the forebay depth at the invert. The
measuring device used to determine the sediment elevation shall be such
that it will give an accurate depth reading. When the depth reading
indicates 2.25 feet, sediment shall be cleaned out of the forebays.
Storm Water Wetland - If the elevation of the marsh area exceeds the
permanent pool elevation by more than 12 inches (other than as designed),
the wetland shall be regraded to design levels (0" to 12" above permanent
pool). This shall be performed by removing the upper 6 inches of soil and
stockpiling it. Then the marsh area shall be excavated to the permanent
pool elevation. Afterwards the stockpiled soil should be spread over the
marsh surface such that its elevation ranges between 0" and 6" above the
permanent pool. The soil should not be stockpiled for more than two
weeks. Replant wetland surface as described in construction drawings.
NOTE: Removed sediment from any device shall be disposed of in an appropriate
manner (in accordance with local, state, and federal regulations) and shall be
handled in a manner that will not adversely impact water quality.
Page 2 of 4

d. Wetland plant densities and species shall be maintained and re-planted in bare
areas as needed. Water newly planted species at a rate of not less than 1-inch per
week (including rainfall) for a period of 90 days after planting.
e. Water entire storm water wetland planted area as necessary during periods of
drought to ensure plant health and vegetation density..
£ If the wetland must be drained for an emergency or for maintenance purposes, the
flushing of sediment through the emergency drain shall be minimized to the
maximum extent practical.
It shall be the responsibility of the Owner to schedule the repair of any deficiencies noted
during an inspection.
A permanent maintenance and inspection easement will be granted to NCDENR -
Division of Water Quality (DWQ) and maintained by the Owner to provide access to the
storm water wetlands. It will be the responsibility of the Owner to secure the appropriate
agreements with future owners should the property be subdivided or sold. Inspections and
maintenance (routine or otherwise) and their scheduling will be the responsibility of the
Owner.
Page 3 of 4

ACKNOWLEDGEMENT:
I acknowledge and agree by my signature below that I am responsible for the
performance of the above listed inspection and maintenance procedures. I agree to notify
NCDENR - DWQ of any problems, other that routine maintenance, with the system prior
to any changes to the system or responsible party.
f''~ ~ ~ /
Print Name: ,/ ~~ r~, ~. ' ~~' A/
Title: u~N=
Address: ~~~
Phone:
Signature(`

~'1~~

Date: ~ / I :-~ ~~
~!
I, ~c~ v . C L ~ ~+-~Yl
County of l~clta ° -
Personally appeared before me this
_, a Notary Public for theiS~tate of North Carolina,
do hereby certify that ~1~ ~ ~ `1Q~ pa~R= ~ SO°~
11 day of ~.)~ ~u.a r~ ~~~`~ ,and
acknowledged the due execution of the forgoing wetland detention maintenance
requirements. Witness my hand and official seal,
My commission expires 1 - 1 O ' ZO r c0
``~~~ei~ue-~~
~'' d~'' p qR y
N r
* * ~EAL
~i' pUBL1C
~'~. COUN~y :~`~~
Page 4 of 4

DWQ Project No. ~fo "' ~ ~J
DIVISION OF WATER QUALITY - 401 EXTENDED DETENTION (and POCKET*) WETLAND WORKSHEET
I. PROJECT INFORMATION (please complete the following information):
Project Name : "(• C Sf (-(
Contact Person:~14A/1S 214SM Aal Phone Number:
For projects with multiple basins, specify which basin this worksheet applies to:
Permanent Pool Elevation "~`r~ • 00 ft
Temporary Pool Elevation 1.1 ft.
Permanent Pool Surface Area ! 1 ~o sq. ft.
Drainage Area
Impervious Area
Forebay Surface Area ~I •
~ • 02
30~'~ ac.
ac.
sq. ft.
Marsh 0"-9" Surface Area 2a~~ sq. ft.
Marsh 9"-18" Surface Area 3! •39 sq. ft.
Micro Pool Surface Area '1 O~-O sq. ft.
Temporary Pool Volume 15 l90 cu. ft.
SA/DA used ~. g~ C~~p •2 9~ /
Diameter of Orifice 2 . o in.
II. REQUIRED ITEMS CHECKLIST
(elevation of the orifice invert out)
(elevation of the outlet structure invert in)
(water surface area at permanent pool elevation)
(on-site and off-site drainage to the basin)
(on-site and off-site drainage to the basin)
(at permanent pool elevation approximately 15%)*
(at permanent pool elevation approximately 35%)*
(at permanent pool elevation approximately 35%)*
(at permanent pool elevation approximately 15%)*
(volume detained on top of the permanent pool)
(surface area to drainage area ratio)*
(draw down orifice diameter)
Initial in the space provided to indicate the following design requirements have been met and supporting documentation is attached. If a
requirement has not been met, attach an explanation of why. At a minimum, a complete stormwater management plan submittal includes
a worksheet for each BMP, design calculations, plans and specifications showing all BMPs and outlet structure details, a detailed
drainage plan and a fully executed operation and maintenance agreement. An incomplete submittal package will result in a request for
additional information and will substantially delay final review and approval of the project
Applicants Initials
ECG The temporary pool controls runoff from the 1 inch rain.
~[[. The basin side slopes are no steeper than 3:1.
A planting plan for the marsh areas with plant species and densities is provided.
~ Vegetation above the permanent pool elevation is specified.
~C~- An emergency drain is provided to drain the basin.
~~ The temporary pool draws down in 2 to 5 days.
~[~ Sediment storage is provided in the permanent pool.
~[L A sediment disposal area is provided.
~~(~ Access is provided for maintenance.
(. A site specific, signed and notarized operation and maintenance agreement is provided.
The drainage area (including any offsite area) is delineated on a site plan.
~- Access is provided for maintenance.
L Plan details for the wetland are provided.
~ Plan details for the inlet and outlet are provided.
~'(V A site specific operation and maintenance agreement, signed and notarized by the responsible party is provided (see
http://h 2o.ehnr.state. nc. us/ncwetlands/oandm.doc).
* Pocket Wetlands have different design parameters and are only assumed to remove 35% TSS -See pp. 19 and 20 of the NC DENR
stormwater BMP Manual, April 1999.10% open water, 50% high marsh, 40% low marsh.