NCS000423_Municipal SCM Operation and Maintenance Plan_20220107

N O R T H C A R O L I N A
High Performance Living
Stormwater Control Measure (SCM) Operation & Maintenance Plan
City of Concord, North Carolina
This Operation and Maintenance (O&M) Plan has been prepared by the City of Concord's Stormwater
Division to address requirements for NPDES Permit No. NCS000423 regarding operation and
maintenance of stormwater control measures (SCMs). Stormwater staff shall annually evaluate this plan,
updating as necessary.
This O&M Plan describes the maintenance activities and procedures the City will continually implement
to ensure the proper functionality of municipally owned SCMs so that the potential for pollutant
discharge from the MS4 may be reduced. The O&M Plan outlines inspection and maintenance
procedures for structural stormwater control measures (SCMs) owned by the City of Concord, NC. The
City has a contract with a third -party Professional Engineer (PE) that conducts the annual inspections
and prepares maintenance recommendations.
This O&M Plan is applicable to the following City owned SCMs:
City Owned SCMs
Fire Station 9 - Sand Filter
Airport South Development Area -
Wet Pond
Fire Station 11 - Sand Filter
Airport - Wet Pond
Traffic Management Center - Wet
Pond
Airport Gravel Lots - Sand Filter 1
Brown Center - Wet Pond
Airport Gravel Lots - Sand Filter 2
Intermodal Transit Center—
Bioretention 1
Airport Terminal - Bioretention
Intermodal Transit Center —
Bioretention 2
Airport Terminal and Parking Deck -
Sand Filter
Attached are O&M procedures for typical SCMs approved for installation by the City of Concord.

Bioretention Inspection and Maintenance Plan
Important inspection and maintenance procedures:
— Immediately after the bioretention cell is established, the plants will be watered twice weekly
if needed until the plants become established (commonly six weeks).
— Snow, mulch or any other material will NEVER be piled on the surface of the bioretention cell.
— Heavy equipment will NEVER be driven over the bioretention cell.
— Special care will be taken to prevent sediment from entering the bioretention cell.
— Once a year, a soil test of the soil media will be conducted.
After the bioretention cell is established, I will inspect it once a month and within 24 hours after every
storm event greater than 1.0 inches. Records of inspection 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.
SCM element:
Potential problems:
How to remediate the problem:
The entire SCM
Trash/debris is present.
Remove the trash/debris.
The perimeter of the
Areas of bare soil and/or erosive gullies
Regrade the soil if necessary to remove the
bioretention cell
have formed.
gully, and then plant a ground cover and
water until it is established. Provide lime
and a one-time fertilizer application.
The inlet device: pipe,
The pipe is clogged (if applicable).
Unclog the pipe. Dispose of the sediment
off -site.
The pipe is cracked or otherwise
Replace the pipe.
damaged (if applicable).
Erosion is occurring in the
Regrade the swale if necessary to smooth
swale (if applicable).
it over and provide erosion control devices
such as reinforced turf matting or riprap
to avoid future problems with erosion.
Stone verge is clogged or covered
Remove sediment and clogged
In sediment (if applicable).
stone and replace with clean stone.
The pretreatment area
Flow is bypassing pretreatment area
Regrade if necessary to route all flow to the
and/or gullies have formed.
pretreatment area. Restabilize the area.
Search for the source of the sediment and
Sediment has accumulated to a depth
remedy the problem if possible. Remove the
greater than three inches.
sediment and restabilize the pretreatment
area.
Provide additional erosion protection such
Erosion has occurred.
as reinforced turf matting or riprap if
needed to prevent future erosion problems.
Weeds are present.
Remove the weeds, preferably by hand.
The bioretention cell:
Best professional practices show that
Prune according to best professional
vegetation
pruning is needed to maintain optimal
practices.
plant health
Plants are dead, diseased or dying.
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.
Tree stakes/wires are present six months
Remove tree stake/wires (which can kill the
after planting
tree if not removed).

SCM element:
Potential problems:
How to remediate the problem:
The bioretention cell:
Mulch is breaking down or has floated
Spot mulch if there are only random void
soils and mulch
away.
areas. Replace whole mulch
layer if necessary. Remove the
remaining much and replace with
triple shredded hard wood mulch at
a maximum depth of three inches.
Soils and/or mulch are clogged with
Determine the extent of the clogging -
sediment
remove and replace either just the top
layers or the entire media as needed.
Dispose of the spoil in an appropriate off -
site location. Use triple shredded hard wood
mulch at a maximum depth of three inches.
Search for the source of the sediment and
remedy the problem if possible.
An annual soil test shows that
Dolomitic lime shall be applied as
pH has dropped or heavy
recommended per the soil test and
metals have accumulated in
toxic soils shall be removed,
the soil media.
disposed of properly and replaced
with new planting media.
The underdrain system
Clogging has occurred.
Wash out the underdrain system.
(if applicable)
The drop inlet
Clogging has occurred.
Clean out the drop inlet. Dispose of
the sediment off -site.
The drop inlet is damaged
Repair or replace the drop inlet.
The receiving water
Erosion or other signs of
Contact the Stormwater Services
damage have occurred at the
at 704-920-5360.
outlet.

Contech StormFilter Inspection and Maintenance Plan
Important inspection and maintenance procedures:
— The drainage area will be carefully managed to reduce the sediment load to the
StormFilter.
— The sedimentation chamber or forebay will be cleaned out whenever sediment depth
exceeds 6 inches.
The StormFilter system will be inspected quarterly. Records of inspection 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.
SCM element:
Potential problem:
How I will remediate the
problem:
Entire SCM
Trash/debris is present.
Remove the trash/debris.
Adjacent pavement (if
Sediment is present on the pavement
Sweep or vacuum the sediment as
applicable)
surface.
soon as possible.
Flow diversion structure
The structure is clogged.
Unclog the conveyance and
dispose of any sediment offsite.
The structure is damaged.
Make any necessary repairs or
replace if damage is too large for
repair.
StormFilter Cartridges
Cartridges not performing as designed
Replace cartridges per
— see Contech I&M document to
manufacturer's recommendations.
determine if cartridge maintenance is
required.
Outlet device
Clogging has occurred.
Clean out the outlet device.
Dispose of the sediment offsite.
The outlet device is damaged
Repair or replace the outlet
device.
Receiving water
Erosion or other signs of damage
Contact the City of Concord
have occurred at the outlet.
Stormwater Services at 704-920-
5555.
4

Dry Extended Detention Basin
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. Records of inspection 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.
SCM element:
Potential problem:
How I will remediate the problem:
The entire SCM
Trash/debris is present.
Remove the trash/debris.
The perimeter of the dry
Areas of bare soil and/or erosive
Regrade the soil if necessary to remove
extended detention basin
gullies have formed.
the gully, and then plant a ground
cover and water until it is established.
Provide lime and a one-time fertilizer
application.
The inlet device: pipe or
The pipe is clogged (if
Unclog the pipe. Dispose of the
swale
applicable).
sediment off -site.
The pipe is cracked or otherwise
Replace the pipe.
damaged (if applicable).
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
dispose of it in a location where it will
not cause impacts to streams or the
SCM.
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
spraying.
5

SCM element:
Potential problem:
How I will remediate the problem:
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
dispose of it in a location where it
will not cause impacts to streams or
the SCM. Revegetate disturbed
areas immediately with sod
(preferred) or seed protected with
securely staked erosion mat.
Water is standing more than
Check outlet structure for clogging.
5 days after a storm event.
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).
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 Stormwater Services
damage have occurred at the
at 704-920-5360.
outlet.

Sand Filter Inspection and Maintenance Plan
Important maintenance procedures:
— The drainage area will be carefully managed to reduce the sediment load to the
sand filter.
— Once a year, sand media will be skimmed.
— The sand filter media will be replaced whenever it fails to function properly after
vacuuming.
The sand filter will be inspected quarterly and within 24 hours after every storm event
greater than 1.0 inches. Records of inspection 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.
SCM element:
Potential problem:
How to remediate the problem:
The entire SCM
Trash/debris is present.
Remove the trash/debris.
The adjacent pavement
Sediment is present on the
Sweep or vacuum the sediment as
(if applicable)
pavement surface.
soon as possible.
The perimeter of the sand
Areas of bare soil and/or erosive
Regrade the soil if necessary to remove the
filter
gullies have formed.
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.
The flow diversion
The structure is clogged.
Unclog the conveyance and dispose of any
sediment off -site.
The structure is damaged.
Make any necessary repairs or replace if
damage is too large for repair.
The pretreatment area
Sediment has accumulated to
Search for the source of the sediment
a depth of greater than six
and remedy the problem if possible.
inches.
Remove the sediment and dispose
of it in a location where it will not cause
impacts to streams or the SCM.
Erosion has occurred.
Provide additional erosion protection
such as reinforced turf matting or riprap if
needed to prevent future erosion problems.
The filter bed and
Water is ponding on the surface
Check to see if the collector system is clogged
underdrain collection
for more than 24 hours after a
and flush if necessary. If water still ponds,
system
storm.
remove the top few inches of filter bed media
and replace. If water still ponds, then consult
an expert.
The outflow spillway
Shrubs or trees have started
Remove shrubs and trees immediately.
and pipe
to grow on the embankment.
The outflow pipe is clogged.
Provide additional erosion protection such as
reinforced turf matting or riprap if needed to
prevent future erosion problems.
The outflow pipe is damaged.
Repair or replace the pipe.
The receiving water
Erosion or other signs of damage
Contact Stormwater Services at 704-920-5360.
have occurred at the outlet.
7

Underground Sand Filter Inspection and Maintenance Plan
Important maintenance procedures:
— The drainage area will be carefully managed to reduce the sediment load to the
sand filter.
— Once a year, sand media will be skimmed.
— The sand filter media will be replaced whenever it fails to function properly after
vacuuming.
The sand filter will be inspected quarterly and within 24 hours after every storm event
greater than 1.0 inches. Records of inspection 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.
SCM element:
Potential problem:
How to remediate the problem:
The entire SCM
Trash/debris is present.
Remove the trash/debris.
The adjacent pavement
Sediment is present on the
Sweep or vacuum the sediment as
(if applicable)
pavement surface.
soon as possible.
The perimeter of the
Areas of bare soil and/or
Regrade the soil if necessary to
sand filter
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.
The flow diversion
The structure is clogged.
Unclog the conveyance and dispose
structure
of any sediment off -site.
The structure is damaged.
Make any necessary repairs or replace
if damage is too large for repair.
The pretreatment area
Sediment has accumulated to
Search for the source of the sediment
a depth of greater than six
and remedy the problem if possible.
inches.
Remove the sediment and dispose of
it in a location where it will not cause
impacts to streams or the SCM.
Remove trash and debris. If access to
Trash has accumulated.
storage area is necessary for removal,
use appropriate safety precautions
such as confined entry rules.
The filter bed and
Water is ponding on the
Check to see if the collector system
underdrain collection
surface for more than 24
is clogged and flush if necessary. If
system
hours after a storm.
water still ponds, remove the top
few inches of filter bed media and
replace. If water still ponds, then
consult an expert.
Grass or other plants are
Do not pull the weeds (may pull out
growing on the surface.
media as well). Wipe them with a
systemic herbicide such as glyphosate
and then return within the week to
remove them by hand. (Another option
is to pour boiling water on them or
steam them.)
M

SCM element:
Potential problem:
How to remediate the problem:
The outflow spillway
The outflow pipe is clogged.
Provide additional erosion
and pipe
protection such as reinforced turf
matting or riprap if needed to prevent
future erosion problems.
The outflow pipe is damaged.
Repair or replace the pipe.
The receiving water
Erosion or other signs of
Contact Stormwater Services
damage have occurred at the
at 704-920-5360.
outlet.

Wetland Inspection and Maintenance Plan
Important maintenance procedures:
— Immediately after the stormwater wetland is established, the wetland plants will
be watered twice weekly if needed until the plants become established
(commonly six weeks).
— No portion of the stormwater wetland will be fertilized after the first initial
fertilization that is required to establish the wetland plants.
— Stable groundcover will be maintained in the drainage area to reduce the
sediment load to the wet detention basin.
— Once a year, a dam safety expert will inspect the embankment.
After the wet detention pond is established, I will inspect it once a month and within 24
hours after every storm event greater than 1.0 inches. Records of inspection 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.
SCM element:
Potential problem:
How to remediate the problem:
The entire SCM
Trash/debris is present.
Remove the trash/debris.
The perimeter of the
Areas of bare soil and/or
Regrade the soil if necessary to
wetland
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.
The inlet device: pipe or
The pipe is clogged (if
Unclog the pipe. Dispose of the
swale
applicable).
sediment off -site.
The pipe is cracked or otherwise
Replace the pipe.
damaged (if applicable).
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 in
Search for the source of the
the forebay to a depth that
sediment and remedy the problem if
inhibits the forebay from
possible. Remove the sediment and
functioning well.
dispose of it in a location where it
will not cause impacts to streams or
the SCM.
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 a pesticide is used, wipe it
on the plants rather than spraying.
10

SCM element:
Potential problem:
How to remediate the problem:
The deep pool, shallow
Algal growth covers over 50% of
Consult a professional to remove and
water and shallow land
the deep pool and
control the algal growth.
areas
shallow water areas.
Cattails, phragmites or other
Remove the plants by wiping them
invasive plants cover 50% of
with pesticide (do not spray) —
the deep pool and shallow
consult a professional.
water areas.
Shallow land remains flooded
Unclog the outlet device
more than 5 days after a
immediately.
storm event.
Plants are dead, diseased or
Determine the source of the problem:
dying.
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.
Best professional practices
Prune according to best professional
show that pruning is needed
practices.
to maintain optimal plant
health.
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
of the deep pools (see
dispose of it in a location where it
diagram below).
will not cause impacts to streams or
the SCM.
The embankment
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.
Evidence of muskrat or
Use traps to remove muskrats and
beaver activity is present.
consult a professional to remove
beavers.
The micropool
Sediment has accumulated
Search for the source of the sediment
and reduced the depth to 75%
and remedy the problem if possible.
of the original design depth
Remove the sediment and dispose
(see diagram below).
of it in a location where it will not
cause impacts to streams or the SCM.
Plants are growing in the
Remove the plants, preferably by
micropool.
hand. If a pesticide is used, wipe it
on the plants rather than spraying.
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 Stormwater Services
damage have occurred at the
at 704-920-5360.
outlet.
11

Wet Detention Basin Inspection and Maintenance Plan
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. Records of inspection 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.
SCM element:
Potential problem:
How I will remediate the problem:
The entire SCM
Trash/debris is present.
Remove the trash/debris.
The perimeter of the wet
Areas of bare soil and/or erosive
Regrade the soil if necessary to remove the
detention basin
gullies have formed.
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.
The inlet device: pipe or
The pipe is clogged.
Unclog the pipe. Dispose of the sediment off-
swale
site.
The pipe is cracked or otherwise
Replace the pipe.
damaged.
Erosion is occurring in the swale.
Regrade the swale if necessary to 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 a
Search for the source of the sediment and
depth greater than the original
remedy the problem if possible. Remove the
design depth for sediment
sediment and dispose of it in a location where
storage.
it will not cause impacts to streams or the
SCM.
Provide additional erosion protection such as
Erosion has occurred.
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 show
Prune according to best professional
that pruning is needed to
practices
maintain optimal plant health.
12

SCM element:
Potential problem:
How I will remediate the problem:
The vegetated shelf
Plants are dead, diseased or dying.
Determine the source of the problem: soils,
(cont'd)
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.
Search for the source of the sediment and
Sediment has accumulated to a
remedy the problem if possible. Remove the
The main treatment area
depth greater than the original
sediment and dispose of it in a location where
design sediment storage depth
it will not cause impacts to streams or the
SCM.
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.
The embankment
Shrubs have started to grow
Remove shrubs immediately.
on the embankment.
Evidence of muskrat or beaver
Use traps to remove muskrats and consult a
activity is present.
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.
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 damage
Contact the local NC Division of Water Quality
have occurred at the outlet.
Regional Office, or the 401 Oversight Unit at
919-733-1786.
13