20061421 Ver 1_Worksheets_20061010

Project Name: Middle Cr Cor
Project No. DWQ 061421
SUBMITTED DESIGN.•
elevations
Permanent Pool (ft) 295.5
Temporary Pool (ft) 296
areas
Permanent Pool SA (sq ft) 13900
Drainage Area (ac) 9.5
Impervious Area (ac) 7.6
Forebay (ft2) 2086
High Marsh (ft2) 4867
Low Marsh (ft2) 4867
Micropool (ft2) 2086
volumes
Temporary Pool (cu ft) 2 43
other parameters
SA/DA 3.36
Orifice Diameter (in) 2
Design Rainfall (in) 1
Linear Interpolation of Correct SA/DA
Im ervious
Next Lowest 70
Project Impervious 80.0
Next Highest 80
~~
REQUIRED DESIGN:
3
0.5 ft. depth ok
13904 sq. ft.
check surfac
80.0
15.007194
35.0
35.0
15.007194
100.0432
6553 u. ft.
.M.oX- C~y~,-.~ -f-o
3.36
0.05 cfs drawdown
5.9 day drawdown
3 ft. Permanent Pool Depth
SA/DA from Table
3.36
3.36
3.36
(n. ! 0 . D~
~-
ok
ok
ok
ok
ch~e'c((k temp
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ch~e~ck ~clrawG
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4 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:
1. 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.). ~ (Q;~ ~(- ~~ Se~L-tw~a,.~~@` ~~~'~
QCCo ~C~.c -rv (~ la-~ fi ~ pla.-r~
The measuring device used to determine the sediment elevation shall be s`dch 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 mai 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%
2 ------------------------------------------- ?-----~
Bottom E vation 294 5%
FOREBAY MAIN ~A1~~ ,~tIF~ ~-~ /~
Page 1 of 2

5. Remove cattails and other indigenous wetland plants when they cover 50% of the basin surface. These
plants shall be 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.
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.
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 2 of 2

DWQ Project No.
DNISION OF WATER QUALITY -401 EXTENDED DETENTION (and POCKET) WETLAND WORKSHEET
1. PROJECT INFORMATION (please complete the
Project Name : r +7 7 ~
Contact Person: SrG'-f
information):
~MGEJS
Phone Number.
For projects with multiple basins, spedfy which-basin this worksheet applies to:
Permanent Pool Elevation 7 Z~ ~ ft. (elevation of the orifice invert out)
Temporary Pool Elevation ~ ?_ 4S• ft. (elevation of the outlet structure invert in)
Permanent Pod Surface Area
Drainage Area
Impervious Area
Forebay Surface Area
Marsh 0"-9" Surface Area
Marsh 9"-18" Surface Area
Micro Pool Surface Area
Temporary Pool Volume
SAIDA used
Diameter of Orifice
II. REQUIRED ITEMS CHECKLIST
Z,(. ~/ K 3 cu. ft.
3.3 ~•
(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 spedfigfions 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
Aoalicants Initials
~S The temporary pool controls runoff from the 1 inch rain.
~'i .The basin side slopes are no steeper than 3:1.
7r~'S A planting plan for the marsh areas with plant spades and densities is provided.
_~AQ Vegetation above the permanent pool elevation is specified.
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.
A sediment disposal area is provided.
~ 5 Access is provided for maintenance.
~ A site spedfic, signed and notarized operation and maintenance agreement is provided.
t >9' The drainage area (including any offsite area) is delineated on a site plan.
Access is provided for maintenance.
7t Plan details for the wetland are provided.
~ _S Plan details for the inlet and outlet are provided.
~ A site specific operation and maintenance agreement, signed and notarized by the responsible party is provided (see
http://h2o.ehnr.state.nc.us/ncwetlands/oandm.doc).
* Pocket Wetlands have different design parameters and are only assumed to remove 35% TSS -See pp.19and 20 of the NC DENR
Stormwater BMP Manual, April 1999. 10°~ open water, 50% high marsh, 40% low marsh.
(~ ~aJ sq. ft.
R.5 ac.
7. G. ac.
20 $ (. sq. ft.
4 I? to 7 sq. ft.
K ~ 3 b 7 sq. ft.
20 rd ~ sq. ft.

DWQ Project No.
DIVISION OF WATER QUALITY • LEVEL SPREADER WORKSHEET
I. PROJECT INFORMATION (please complete the following information):
Project Name : M r~ ~ L~ L-~- C-6wl /Y1urJ5
Contact Person: a~ ri+.~ CeV~n- , ~- Phone Number. (9 ~ R) ~? - bu 3
Level Spreader ID:.
Level Spreader Length z ~ ft.
Drainage Area 9.s ac.
Impervious Area . Lo ac.
Maximum Filter Strip/Buffer Slope (
grass
(perpendicular to flow)
(on-site and off-site drainage to the level spreader)
(on-site and off-site drainage to the level spreader)
(ti% for forested, leaf littler cover, 8% for thick ground cover)*
Max. Discharge from a 10 Year Storm ~• `I cfs
Max. Discharge to Level Spreader cfs
Filter Strip/Buffer Vegetation ~at'C.. ,, Gd,,,Y (thick ground cover or grass, canopied forest with leaf litter
groundcover)
Pre-treatment or Bypass Method
tl. REQUIRED ITEMS CHECKLIST
t..SNSTi' /efir~ ~L71~~
Initial in the space provided to indicate the following design requirements have been met and supporting documentation is attached. Ha
requirement has not been met, attach an explanation of why. At a minimum, a complete stormwater management plan submittal incudes
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.
A licants Initials
Level spreader is at least 13 ft. per cfs for thick ground cover or grass or 100 ft per cfs in canopied forest with leaf
litter.
~ Pre-Form Scour Holes are on flat slopes only
~ No structures are located in protected buffers*
If bypass method specified in the Draft Level Spreader Design Option Document:
J ~ Bypass method is specified (if applicable} and plan details and calculations are provided
`~fS Discharge to level spreader and subsequent filter strip is hydraulically and spatially separate from the bypass
discharge.
~'S No structures are located in protected buffers.
'Q<J1 Plan details for the bypass and outlets are provided,
'~~'S The operation and maintenance agreement includes annual erosion and vegetation repair.
t)trc The operation and maintenance agreement signed and notarized by the responsible party is provided.
* Level spreaders in series can be used on slopes of up to 15°~ in forested areas with leaf littler cover or on slopes of up to 25% in areas
with thick ground cover or grass if designed according to the Draft Level Spreader Design Option Document This potentially requires a
minor variance in protected buffer areas. In any event the second level spreader cannot be located in Zone 1 of a protected buffer area.