SW3140903_O&M Agreement/Plan_20210809 (4)

Permit Number:
(to be provided by D TVQ)
Drainage Area Number:
Dry Extended Detention Basin
Overation and N' - e
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 integrih,
of structures, safety of the public, and the removal efficiency of the BMP.
The dry extended detention basin system is defined as the dry detention basin, outlet
structure, pretreatment including forebays and the vegetated filter if one is provided.
This system (check one):
Eldoes ❑ does not incorporate a vegetated filter at the outlet.
This system (check one):
❑ does ❑ does not incorporate pretreatment other than a forebay.
Important maintenance procedures:
— The drainage area will be managed to reduce the sediment load to the dry
extended detention basin.
— Immediately after the dry extended detention basin is established, the vegetation
will be watered twice weekly if needed until the plants become established
(commonly six weeks).
— No portion of the dry extended detention pond will be fertilized after the first
initial fertilization that is required to establish the vegetation.
— I will maintain the vegetation in and around the basin at a height of
approximately six inches.
— Once a year, a dam safety expert will inspect the embankment.
After the dry extended detention basin is established, it will be inspected once a quarter
and within 24 hours after every storm event greater than 1.0 inches (or 1.5 inches if in
a Coastal County). Records of operation and maintenance 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 problem:
How I will remediate the problem:
The entire BMP
Trash/ debris is -present.
Remove the trash/ debris.
The perimeter of the dry
Areas of bare soil and/or
Regrade the soil if necessary to
extended detention
erosive gullies have formed.
remove the gully, and then plant a
basin
ground cover and water until it is
established. Provide lime and a
one-time fertilizer application,
Form SW40 I -Dry Detention O&M-Rev.3 Page 1 of 4

BMP element:
Potential problem:
How I will remediate the problem:
The inlet device: pipe or
swale
The pipe is clogged (ff
applicable).
Unclog the pipe. Dispose of the
sediment off -site.
The pipe is cracked or
Replace the pipe.
otherwise damaged (if
Erosion is occurring in the
Regrade the swale if necessary to
swale (if applicable).
smooth it over and provide erosion
control devices such as reinforced
turf matting or riprap to avoid
future problems with erosion.
The forebay
Sediment has accumulated
Search for the source of the
and reduced the depth to 75%
sediment and remedy the problem if
of the original design depth
possible. Remove the sediment and
(see diagram below).
dispose of it in a location where it
will not cause impacts to streams or
the BMP.
Erosion has occurred or
Provide additional erosion
riprap is displaced.
protection such as reinforced turf
matting or riprap if needed to
prevent future erosion problems.
Weeds are present.
Remove the weeds, preferably by
hand. If pesticides are used, wipe
them on the plants rather than
The main treatment area
Sediment has accumulated
Search for the source of the
and reduced the depth to 75%
sediment and remedy the problem if
of the original design depth
possible. Remove the sediment and
(see diagrarn below).
dispose of it in a location where it
will not cause impacts to streams or
the BMP. Revegetate disturbed
areas immediately with sod
(preferred) or seed protected with
securely staked erosion mat.
Water is standing more than
5 days after a storm event.
Check outlet structure for clogging.
If it is a design issue, consult an
appropriate professional.
Weeds and noxious plants are
Remove the plants by hand or by
growing in the main
wiping them with pesticide (do not
treatment area.
spray).
Form SW40i-Dry Detention 0&K4-Rov3 Page 2nf4

BMP element:
Potential problem:
How I will remediate the problem:
The embankment
Shrubs or trees have started
Remove shrubs or trees
to grow on the embankment.
immediately,
Grass cover is unhealthy or
Restore the health of the grass cover
eroding.
-.consult a professional if necessary.
Signs of seepage on the
Consult a professional.
downstream face.
Evidence of muskrat or
Use traps to remove muskrats and
beaver activity is present.
consult a professional to remove
beavers.
An annual inspection by an
Make all needed repairs.
appropriate professional
shows that the embankment
needs repair.
The outlet device
Clogging has occurred.
Clean out the outlet device. Dispose
of the sediment off -site.
The outlet device is damaged
Repair or replace the outlet device.
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.
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 basin depth reads 554.48 feet in the main pond, the sediment shall be
removed.
When the basin depth reads 554.00 feet in the forebay, the sediment shall be removed.
BASIN DIAGRAM
Vi I in the blanks)
Temporary Pool Elevation 555.75
Sediment Removal E 554.00 � Te pora Pool emporary
------------------ olume Sediment Removal Elevation 554.48 Volume
io 5
Bottom Elevatio 553.00 25% ------------------------------------- ------
Sediment
Bottom Elevation 551.50 Xo
Sedimen\t 250je�
e Storaa
ZD Sto
FOREDAY MAIN POND
Form SW401 -Dry Detention O&M-Rev.3 Page 3 of 4

Permit Number
(to be provided by D 1,VQ)
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.
Project naine:Oak Grove Estates
BiVIP drainage area number:Dry Basin D
Print name:Justin Demers
Title:Board President
Address:5127 Oak Grove Place Waxhaw. NC 28173
Phone:[phone]
Signature:
Date:
I Z-
Note: The legally responsible part), 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 �
D J/-'L P V7 a Notary Public for the State of
V
County of do hereby certify that
personally appeared before methis
day of and acknowledge the due execution of the
forgoing dry detention basin maintenance requirements. Witness my hand and official
seal,
0 N P
tAOTA
L IC
OU
4118t2aal %%%%
SEAL
J
My commission expires
Form SW401-Dry Detention O&M-Rev.3 Page 4 of 4
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