20061421 Ver 1_More Info Received_20061002

•
Soil & Environmental Consultants, PA
11010 Raven Ridge Road Raleigh, North Carolina 27614 Phone: [phone] Fax: [phone]
www.SandEC.com
September 29, 2005
S&EC Project #10409.W2
DWQ Project #06-1421
Department of Environment and Natural Resources
Division of Water Quality
Attn: Cyndi Karoly/Cynthia Van Der Wiele/Lia Myott
2321 Crabtree Boulevard p ~~~~~
Suite 250 ~ D
Raleigh, NC 27604
ocr ~ Zoos
Re: Reply to the Division of Water Quality's Request for More Information
Middle Creek Commons-EXPRESS REVIEW PROGRAM OENR - -wATER
~~~ANDST QUAUTy
Clayton, Johnston County, NC ORMW,~~ B~CH
To Whom It May Concern:
The purpose of this letter is to respond to your Request for More Information letter dated September 22, 2006. In
order to clarify the extent of the outstanding issues, a meeting was conducted on September 27, 2006. The original
questions/requests are copied below as they appear within letter and are then followed by our response.
Additional Information Requested:
1. Stormwater Management:
a. The extended detention wetland does not appear to have a forebay (sheet C4.1)
The wetland detention basin has been modified to include the necessary design as discussed in our meeting on
September 27, 2006, please see sheet C4.0.
b. Please consult the information in the 1999 DENR Stormwater BMP Manual for extended detention wetlands,
particularly Figure2 on page 14. DWQ has concerns about the routing of the stormwater within your wetland.
This relates to our concerns regarding the drawdown period.
The wetland detention basin has been modified to include the necessary design as discussed in our meeting on
September 27, 2006, please see sheet C4.0.
c. The sheet C4.1 appears to be exactly the same as the previous submittal. Please re-examine your planting plan.
DWQ has concerns with the water depths and spacing you have indicated for some of your plant material.
The wetland detention basin has been modified to include the necessary design as discussed in our meeting on
September 27, 2006, please see sheet C4.0.
d. The orifice appears to be sized incorrectly for optimum drawdown. Please recheck this parameter. According
to our calculations, your drawdown is 1 S+ days.
The orifice has been modified to be 2" in size as discussed in our meeting on September 27, 2006, please see
sheet C4.0 and revised worksheet.
e. Operations and Maintenance Agreement.• The submitted document appears to be more suited to a wet detention
basin. DWQ has concerns that the second item in the maintenance activity would imply that a person should mow
the entire constructed wetland. Item number 4 is vague and discusses the permanent pool depth in the main pond;
constructed wetlands have micropools rather than main ponds. Will replanting of wetland plant material occur
Charlotte Office:
236 LePhillip Court, Suite C
Concord, NC 28025
Phone: [phone]
Fax: [phone]
Greensboro Office:
3817-E Lawndale Drive
Greensboro, NC 27455
Phone: [phone]
Fax [phone]

after sediment removal? This is not clear in your Operations and Maintenance Agreement. What do you mean by
"Remove cattails and other indigenous wetland plants when they cover SO% of the basin surface "? Most of the
constructed wetland is planted with wetland plants and could lead someone to think that all plants should be
removed. It is confusing and not an appropriate instruction for an extended detention wetland. Please redraft your
Agreement and resubmit.
The Operations and Maintenance Agreement has been modified for the Wetland Detention Basin to include
the necessary language as discussed in our meeting on September 27, 2006, please see the Wetland Detention
Basin Operations and Maintenance Agreement attached. In addition, please see the Level Spreader
Operations & Maintenance Agreement. As with our previous submittal, these documents are unsigned for
your review. If acceptable, we will have signed and notarized and returned for the final DWQ approvals and
file.
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, _`t'~ ~,
Debbie Edwards
Environmental Specialist
CC: David Smith-Regency Centers, 101 Maynard Crossing Court, Suite 211, Cary, NC 27513
Attachments:
1) Revised Operations & Maintenance Agreements (Wetland Detention & Level Spreader)
2) Revised Extended Detention Wetland Worksheet
3) Plan Sheet C4.0

MIDDLE CREEK COMMONS, JOHNSTON COUNTY, NC
WETLAND DETENTION BASIN OPERATION AND MAINTENANCE AGREEMENT
This is the Operation and Maintenance plan for the wetland detention basin system at Middle Creek Commons
in the Cleveland Community, Johnston County, NC.
Maintenance activities shall be performed as follows:
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. Generallnspection
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. Inspect and repair the collection system (i.e.
catch basins, piping, swales, riprap, etc.) quarterly to maintain proper functioning.
3. Structurallnspection
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).
c) Inspect for erosion along the wetland perimeter and dam embankment. 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.
e) Inspect the embankment for evidence of seepage along the downstream embankment face to include
the vicinity of the outlet flared-end section.
Page 1 of 3

4. Maintenance and Repairs
Maintenance and repair activities shall include:
a) 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.
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.
d) Remove cattails and other indigenous wetland plants when they cover 25% of the wetland surface.
These plants may be encouraged to grow along the edge of the wetland and the forebay berm as long
as they do not interfere with hydraulic function orout-compete desired (see planting plan) plant
species.
e) 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.
f) Water entire storm water wetland planted area as necessary during periods of drought to ensure plant
health and vegetation density.
g) 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 2 of 3

I acknowledge and agree by my signature below that I am responsible for the performance of the seven
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:
Title:
Address:
Phone:
Signature:_
Date:
a Notary Public for the State of
County of , do hereby certify that
personally appeared before me this day of ,and acknowledge the due
execution of the forgoing wet [wetland] detention basin maintenance requirements. Witness my hand and
official seal,
SEAL
My commission expires
Page 3 of 3

MIDDLE CREEK COMMONS, JOHNSTON COUNTY, NC
LEVEL SPREADER OPERATION AND 11fiAINTEiVANCERGREEMENT
The level spreader is defined as an elongated, level threshold, designed to diffuse stormwater runoff:
Maintenance activities shall be performed as follows:
1. After construction and until vegetation has been established, level spreader(s) shall be inspected after
every rainfall. Thereafter, level spreader(s) shall be inspected at least every month and more
r'requentfy during the fall season and after heavy rainfall events:
a. Accumulated sediment, leaves, and trash shall be removed, and repairs made if required.
b. Inspect level spreader(s) for evidence of scour, undercutting, settlement of the structure, and
concentrated flows downhill from the level spreader(s).
c. A level elevation shall be maintained across the entire flow-spreading structure at all times.
Repair or replace the level spreader if it is damaged.
d. Mow vegetative cover to a height of six (5) inches and prune plants if they cover over half of the
level spreader surface.
e. Repair eroded areas and replace/replant dead or damaged vegetation.
2. The contractor should avoid the placement of any material on and prevent construction traffic across
the structure. If the measure is damaged by construction traffic, it shall be repaired immediately.
3. Inspect and repair the collection system (e.g., catch basins, pipes, swales, riprap) four (4) times a year
to maintain proper functioning.
I acknowledge and agree by my signature below that I am responsible for the performance of the maintenance
procedures listed above. I agree to norfy CUv ~ of any problems with the system or prior to any changes to
the system or responsible party.
Print name:
Title:
Address:
Phone:
Signature:_
Date:
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.
a Notary Public for the State of
County of , do hereby certify that
personally appeared before me this day of ,and acknowledge the due
execution of the forgoing wet [wetland] detention basin maintenance requirements. Witness my hand and
offlCi81 Seal,
SEAL
My commission expi
Page 1 of 1

DUtrQ Project No.
~ttrlSfUty CDF ~k,°R.TEf~ f4~~.LfTY ~ 4Ct1 EXTEEtDEr? LETEF<~TIC~ (a~t~ PDGKET*J lrt~~b~[!~ Ef~C11~1~~I~~ET
t. Pi~QJECT itdFD~[~cl;TiDtE (please complete the following information~•
PropctName • fry ~~ ~~~ ~(~.~ r_ ~;.~~~' cki~•~
Contact Person:
Phone Number.
F~
For projects with multiple basins, specify which basin this worksheet applies to:
Permanent Pool Elevation ~- ~ ~ ft. (elevation of the orfice invert out)
Temporary Pool Elevation ~.5~• . fk (elevation of the outlet structure invert in)
Permanent Pool Surface Area f f $~ ~ sq. ft. (ureter surface area at penmanent pool elevation)
Drainage Area ~'•.~ ac. (on-site and off-site drainage to the basin)
Impervious Area ~ . „~^ ac. (on-site and off-site drainage th the basin)
Forebay Surface Area 6 ~' ~ ~ sq. ft. (at pemtianant poot elevation approximately 15°k}`
Marsh 0"-9" Surface Area ~' u =~ sq. P~ (at permanent pool elevation approximately 35%}*
flRarsh 9°-18" Surface Area ~`U ~~ ` sq. ft. (at pem~anent poo! elevation approximately 35°/0)'
Micro Pool Surface Area t -~",~ td sq. ft. (at pem~anent pool elevation approximately 15°Jo}*
Temporary Poo(Volume ~ ~' ~ d ~ cu. ft. (volume detained on top of the permanent pool)
SA/DA used ~ ~ ~ (surface area to drainage area ratio)*
Diameter of Orifice ~ . cy' _ in. (draw dov~m orifice diameter)
i2. f~E~UiREf# fTEf~S CFtECtryt.fST
Initial in-the space proaided fo 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 managerr~nt plan submittal includes
a worksheet for each 6f~NP, design ca~ulations; plans and speaiica ions showing a!I BfJIPs and outlet structure de`~ails, a detailed
drainage plan and a fully executed opera6an and maintenamce agreement. An irreomplete submittal pa~:age will result in a request for
additional information and will substantially delay final review and approval ofi the project
- •~-€~ The temporary pmt cx~ntrois runoff from the '!mch rain.
~{~k The basin side slopes are no sleeper than 3:1.
~ A planting plan for the marsh areas with p{ant species and densities is provided.
:~z~ " Vegetation above the permanent poo! elevation is specified.
~~ An emergency drain is provided to drain the basin.
`h i~:~' The temporary pool draws down in 2 to 5 days.
i~~ Sediment storage is provided in the pemtanent pool.
i~~~S A sediment dispose! area is provided.
~,~ .a Access is pro~~ded for maintenarx~.
4? ~.~` A site speCtflC, Signed and notarized oparaFJon and e~aintenance agreement is provided.
~` ' ~~ The drainage area (including any offsife area) is delineated on a sire pian.
1~ Access is provided for maintenance.
t?r~T Plam details for the aa:tland are provided.
~~w: Plan details for the inlet and ouriet are provided.
E ~~ A site spa:ifK operation and maintenance agreement, sigm~i and notarized by the responsible par#y is provided {see
htfpa/h2o.ehnrstate.nc.us/ncwetlandsloandm.doc).
* Pocket Udeflands have different design parameters and are only assumed to remove 35% TSS -See pp.19and 20 of the tJC DEI~fP
Stormwater BfNP Manual, April 1999.10% open water, 50% high marsh, 40% low marsh.

,,.
PROJECT: Middle Creek Commons
BMP#1 Wetland
26-Sep-06
DETERMINE SURFACE AREA AND VOLUME REQUIRED
DRAINAGE AREA (DA):
SUBDIVISION LOT SIZE:
IMPERVIOUS AREA:
68%
SA/DA (FROM TABLE 1.1 NC BMP MANUAL): 2.78
SURFACE AREA REQUIRED: 11,504 SF
RUNOFF VOLUME(Rv) _ .05+(.009''%IMP.*100): 0.66 IN/IN
VOLUME REQUIRED (V) = Rv*1"*DA 22,820 CF
POND DEPTH CRITERIA:
HIGH MARSH (0-9" DEPTH) MIN .35% OF SA 4,026 SF
LOW MARSH (9-18" DEPTH) MIN. 35% OF SA 4,026 SF
OPEN WATER (> 18" DEPTH) MIN. 15% OF SA 1,726 SF
BALANCE OF AREA (15%): 1,726 SF
TOTAL SURFACE AREA: 11,504 SF
STAGE STORAGE TABLE
CONTOUR CONTOUR
AREA
SF INCR
VOLUME
CF ACCUM
VOLUME
CF Z
STAGE
FT % OF
NP
294 1,683 -2 15% >18"
295 5,801 -1 36% 9-18"
296 11,567 < -NORMAL POOL 0 50% 0-9"
297 13,176 12372 12,372 1 100%
298 14,852 14014 26,386 2
299 16,595 15724 42,109 3
9.50 ACRES
na ACRE
0
1
2
1.75
VOLUME CHECK (PROPOSED/REQUIRED): 1.16

STORAGE POOL DRAWDOWN
BMP#1 Wetland
ORFICE EQUATION: Q=CpA(2gh)~~Z
Number of Drains:
Diameter of Drains:
Area of Opening:
Orifice Coefficient:
Average Head: (Q10 el - NP el)/2
Average Flow (Orifice Equation=
Volume of Storage =
1
2.0 in
0.0218 ft
0.60 ft
0.75 ft
0.091 cfs
22,820 cf
Length of Drawdown = 250,970 sec or 69.71 hours OK