SW5210202_O&M Agreement_20210224

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: Potential problem: How I will remediate the problem:
The entire BMP
Trash/debris is present. Remove the trash/debris.
The perimeter of the wet
Areas of bare soil and/or Regrade the soil if necessary to
detention basin
erosive gullies have formed. remove the gully, and then plant a
ground cover and water until it is
established. Provide lime and a
one-time fertilizer application.

Vegetation is too short or too Maintain vegetation at a height of
long. approximately six inches.
Form SW401-Wet Detention Basin O&M-Rev.4 Page 1 of 4

Permit Number:_______________________
(to be provided by DWQ)
Drainage Area Number:_________________

BMP element: Potential problem: How I will remediate the problem:
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.
otherwise damaged.
Erosion is occurring in the Regrade the swale if necessary to
swale. 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 to Search for the source of the
a depth greater than the sediment and remedy the problem if
original design depth for possible. Remove the sediment and
sediment storage. dispose of it in a location where it
will not cause impacts to streams or
the BMP.
Erosion has occurred. Provide additional erosion
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 pesticide is used, wipe it on
the plants rather than spraying.
The vegetated shelf
Best professional practices Prune according to best professional
show that pruning is needed practices
to maintain optimal plant
health.
Plants are dead, diseased or Determine the source of the
dying. 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.
Weeds are present. Remove the weeds, preferably by
hand. If pesticide is used, wipe it on
the plants rather than spraying.
The main treatment area
Sediment has accumulated to Search for the source of the
a depth greater than the sediment and remedy the problem if
original design sediment possible. Remove the sediment and
storage depth. dispose of it in a location where it
will not cause impacts to streams or
the BMP.
Algal growth covers over Consult a professional to remove
50% of the area. and control the algal growth.

Cattails, phragmites or other Remove the plants by wiping them
invasive plants cover 50% of with pesticide (do not spray).
the basin surface.
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: Potential problem: How I will remediate the problem:
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 _5_ feet in the main pond, the sediment
shall be removed.

When the permanent pool depth reads _4_ feet in the forebay, the sediment shall
be removed.

BASIN DIAGRAM
(fill in the blanks)

Permanent Pool Elevation 249

Sediment Removal El. 246 Permanent Pool
Volume Sediment Removal Elevation 245 Volume
Bottom Elevation 245 1-ft Min.
Sediment Bottom Elevation 244 1-ft Min.
Storage Sediment
Storage
FOREBAY MAIN POND

Form SW401-Wet Detention Basin O&M-Rev.4 Page 3 of 4

Permit Number:_______________________
(to be 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:Franklin County E911
BMP drainage area number:1.44 acres

Print name:Kim Denton
Title: County Manager
Address:113 Market Street
Phone:[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 detention basin maintenance requirements. Witness my hand and official
seal,

SEAL

My commission expires

Form SW401-Wet Detention Basin O&M-Rev.4 Page 4 of 4