20061421 Ver 1_More Info Received_20060920

Environmental Consultants, PA
Road Raleigh, North Carolina 27614 Phone: [phone] Fax: [phone]
Department of Environment and Natural Resources
Division of Water Quality
Attn: Cyndi Karoly/Cynthia Van Der Wiele/Lia Myott
2321 Crabtree Boulevard
Suite 250
Raleigh, NC 27604
Re: Reply to the Division of Water Quality's Request for More Information
Middle Creek Commons-EXPRESS REVIEW PROGRAM
Clayton, Johnston County, NC
September 20, 2005
S&EC Project #10409.W2
DWQ Project#06-1421
To Whom It May Concern: ''~° -•
The purpose of this letter is to respond to your Request for More Information letter dated September 15, 2006. The
original questions/requests are copied below as they appear within letter and are then followed by our response.
Additional Information Requested:
1. Wetland Impacts:
a. DWQ feels that impact #3 (level spreader) could be eliminated or minimized through a reduction in pipe length
and rip rap energy dissipater pad.
As stated in the PCN application, this outlet structure is located within the wetland because the site is fairly
flat, and the stormwater piping system required large diameter pipes at flat slopes with minimum cover to
establish the elevation of the BMP pond. The outlet pipe has been raised as high as possible and even with all
of the above measures; the vertical fall of this pipe is deficient in order to daylight outside of the existing
wetland and avoid these impacts.
In addition, the invert of the outlet pipe is at elevation 295.0, and in order for the pipe to daylight; it has to be
extended into the wetland. If the preference is to stop the pipe at the wetland, then a channel will have to be
constructed into the wetland to allow the pipe to flow. This in turn would require a larger impact to the
wetland than the construction of the pipe because more excavation would be needed to excavate for the
channel. The level spreader is proposed to keep the flow diffuse and eliminate potential erosion within the
wetland
2. Stormwater Management:
a. Please include a typical detail for the level spreader.
The level spreader detail has been added, please see new sheet C4.1.
b. Please include your construction phasing with regard to the extended detention wetland and your planting
schedule.
Sheet C4.0 has been modified to include this information
c. Please re-examine your planting plan. DWQ has concerns with the water depths and spacing you have
indicated jor some of your plant material.
Charlotte Office: 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]

The planting plan has been adjusted on sheet C4.0.
d. The orifice appears to be sized incorrectly for optimum drawdown. Please recheck this parameter.
The calculations are showing a 1" diameter for the drawdown between 2 - 5 days, which is shown on the
plans. Please advise if you prefer a different time frame.
e. Operations and Maintenance Agreement: You have submitted a "Reservoir Watershed Protection Impoundment
Maintenance Agreement ". The maintenance fails to address the level spreader and is incompatible with the
operations and maintenance of a constructed wetland. Please redraft your Agreement and resubmit.
An unsigned, modified Operations & Maintenance Agreement is attached 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,
Debbie Edwards
Environmental Specialist
CC: David Smith-Regency Centers, 101 Maynard Crossing Court, Suite 211, Cary, NC 27513
Attachments:
1) Plan sheets C4.0 & C4.1
2) Modified Operations & Maintenance Agreement

MIDDLE CREEFC COMMONS, JOHNSTON COUNTY, NC
LEVEL SPREADER OPERATION AND MAINTENANCE AGREEMENT
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 leasf every month and more
frequently 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 (6) 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 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:
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
official seal,
SEAL
My commission expires
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MIDDLE CREEK COMMONS, JOHNSTON COUNTY, NC
WETLAND DETENTION BASIN OPERATION AND MAINTENANCE AGREEMENT
The wetland detention basin system is defined as the wetland detention basin, pretreatment including forebays
and the vegetated filter if one is provided.
Maintenance activities shall be performed as follows:
After every significant runoff producing rainfall event and at least monthly:
a. Inspect the wetland detention basin system for sediment accumulation, erosion, trash accumulation,
vegetated cover, and general condition.
b. Check and clear the orifice of any obstructions such that drawdown of the temporary pool occurs within
2 to 5 days as designed.
2. Repair eroded areas immediately, re-seed as necessary to maintain good vegetative cover, mow
vegetative cover to maintain a maximum height of six inches, and remove trash as needed.
3. Inspect and repair the collection system (i.e. catch basins, piping, swales, riprap, etc.) quarterly to
maintain proper functioning.
4. Remove accumulated sediment from the wetland detention basin system semi-annually or when depth is
reduced to 75% of the original design depth (see diagram below). Removed sediment shall be disposed
of in an appropriate manner and shall be handled in a manner that will not adversely impact water quality
(i.e. stockpiling near a wetland detention basin or stream, etc.).
The measuring device used to determine the sediment elevation shall be such that it will give an accurate
depth reading and not readily penetrate into accumulated sediments.
When the permanent pool depth reads 294.5 feet in the main pond, the sediment shall be
removed.
For stormwater wetlands: If the elevation of the marsh areas exceed the permanent pool elevation, the
sediment should be removed to design levels. This shall be performed by removing the upper 6 inches of
soil and stockpiling it. Then the marsh area shall be excavated six inches below design elevations.
Afterwards the stockpiled soil should be spread over the marsh surface. The soil should not be stockpiled
for more than two weeks.
When the permanent pool depth reads 294.5 feet in the forebay [and micro-pool], the sediment
shall be removed.
BASIN DIAGRAM
Permanent Pool Elevation 296
Sediment moval EI. 294. 75%
-------------- -- Sediment Removal Elevation 294.5 75%
------------------------------- ------
Bottom E vation 294 5%
0
FOREBAY MAIN POND
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5. Remove cattails and other indigenous wetland plants when they cover 50% of the basin surface. These
n s s all a encouraged to grow along the vegetated shelf and forebay berm.
For wetlands: Wetland planting densities in the marsh areas should be maintained by replanting bare
areas as needed. Wetland plants should be encouraged to grow in the marsh areas.
6. If the basin must be drained for an emergency or to perform maintenance, the flushing of sediment
through the emergency drain shall be minimized to the maximum extent practical.
7. All components of the wetland detention basin system shall be maintained in good working order.
8. Level spreaders or other structures that provide diffuse flow shall be maintained every six months. All
accumulated sediment and debris shall be removed from the structure, and a level elevation shall be
maintained across the entire flow spreading structure. Any down gradient erosion must be repaired and/or
replanted as necessary.
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:
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, , 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
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