SW6090701_O&M Agreement_20090708

Permit Number:
(to be provided by DWQ)
Drainage Area Number:
Wet Detention Basin Operation and Maintenance Agreement
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 integrity
of structures, safety of the public, and the removal efficiency of the BMP.
The wet detention basin system is defined as the wet detention basin,
pretreatment including forebays and the vegetated filter if one is provided.
This system (check one):
❑ does ® 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:
— Immediately after the wet detention basin is established, the plants on the
vegetated shelf and perimeter of the.basin should be watered twice weekly if
needed, until the plants become established (commonly six weeks).
— No portion of the wet detention pond should be fertilized after the first initial
fertilization that is required to establish the plants on the vegetated shelf.
— Stable groundcover should be maintained in the drainage area to reduce the
sediment load to the wet detention basin.
— If the basin must be drained for an emergency or to perform maintenance, the
flushing of sediment through the emergency drain should be minimized to the
maximum extent practical.
— Once a year, a dam safety expert should inspect the embankment.
After the wet detention pond is established, it should be inspected once a month 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 should be kept in a known set
location and must be available upon request.
Inspection activities shall be performed as follows. Any problems that are found shall
be repaired immediately.
BMP element.
Potentialproblem:
How I will remediate theproblem:
The entire BMP
The perimeter of the wet
detention basin
Trash/debris is present.
Areas of bare soil and/or
erosive gullies have formed.
Remove the trash/debris.
Regrade the soil if necessary to
remove the gully, and then plant a
ground cover and water until it is
established. Provide lime and a
one-time fertilizer a lica 'on.
Vegetation is too short or too
lon
Maintain vegetation at a height of
a roximatel six inches.
Form SW401-Wet Detention Basin O&M-Rev.4 Page 1 of 4

Permit Number:
(Io be provided by DWQ)
Drainage Area Number:
BMP element: Potential roblem: How I will remediate theproblem:
The inlet device: pipe or The pipe is clogged. Unclog the pipe. Dispose of the
Swale sediment off -site.
The pipe is cracked or Replace the pipe.
vegetated shelf
main treatment area
Erosion is occurring in
swale.
Sediment has accumulated to
a depth greater than the
original design depth for
sediment storage.
occurred.
are present.
Best professional practices
show that pruning is needed
to maintain optimal plant
health.
Plants are dead, diseased or
dying.
Weeds are present.
Sediment has accumulated to
a depth greater than the
original design sediment
storage depth.
Algal growth covers over
50% of the area.
Cattails, phragmites or other
invasive plants cover 50% of
the basin surface.
Regrade the swale if necessary to
smooth it over and provide erosion
control devices such as reinforced
turf matting of riprap to avoid
future problems with erosion.
Search for the source of the
sediment and remedy the problem if
possible. Remove the sediment and
dispose of it in a location where it
will not cause impacts to streams or
the BMP.
Provide additional erosion
protection such as reinforced turf
matting or riprap if needed to
prevent future erosion problems.
Remove the weeds, preferably by
hand. If pesticide is used, wipe it on
the plants rather than spraying.
Prune according to best professional
practices
Determine the source of the
problem: soils, hydrology, disease,
etc. Remedy the problem and
replace plants. Provide a one-time
fertilizer application to establish the
ground cover if a soil test indicates
it is necessary.
Remove the weeds, preferably by
hand. If pesticide is used, wipe it on
the plants rather than spraying.
Search for the source of the
sediment and remedy the problem if
possible. Remove the sediment and
dispose of it in a location where it
will not cause impacts to streams or
the BMP.
Consult a professional to remove
and control the algal growth.
Remove the plants by wiping them
with pesticide (do not spray).
Form SW401-Wet Detention Basin O&M-Rev.4 Page 2 of 4

Permit Number:
(to be provided by DWQ)
Drainage Area Number:
BMP element:
Potentialproblem:
How I will remediate theproblem:
The embankment
Shrubs have started to grow
Remove shrubs immediately.
on the embankment.
Evidence of muskrat or
Use traps to remove muskrats and
beaver activity is present.
consult a professional to remove
beavers.
A tree has started to grow on
Consult a dam safety specialist to
the embankment.
remove the tree.
An annual inspection by an
Make all needed repairs.
appropriate professional
shows that the embankment
needs repair. if applicable)
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 local NC Division of
damage have occurred at the
Water Quality Regional Office, or
outlet.
the 401 Oversight Unit at 919-733-
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 permanent pool depth reads 154.00 feet in the main pond, the
sediment shall be removed.
When the permanent pool depth reads 154.00 feet in the forebay, the sediment
shall be removed.
Sediment Removal
Bottom
154.00 I ,
------------------
FOREBAY
BASIN DIAGRAM
Oil in the blanks)
tft Min.
Sediment
Storage
Permanent Pool Elevation 157.00
Sediment Removal Elevation 154.00 Vol um,
----------------------- ------
Bottom Elevation
MAIN POND
1-ft
Storage
Form S W401-Wet Detention Basin O&M-Rev.4 Page 3 of 4

Permit Number:
(robe provided by DWQ)
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 name:Grays' Creek Middle School
BMP drainage area number:one
Print name:Mr. Wilson Lacy
Title:Director of Operations.
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.
1, �:M 01 an i P "Di I6(0/) , a Notary Public for the State of
t`40Y /1 eO-Ct)A g County of , m g.A 4 do hereby certify that
l(J� ��SD/1 LLP u personally appeared before me this LA
day of aDU 9 , and acknowledge the due execution of the
forgoin et etention basin maintenance requirements. Witness my hand and official
seal,
SEAL
My commission expirQs�
Form SW401-Wet Detention Basin O&M-Rev.4 Page 4 of 4