22-102749-UP-Operation & Maintenance Manual-06-15-2022-V1
OPERATIONS AND MAINTENANCE MANUAL
FOR
PLANT 2 RELOCATION
JUNE 9, 2022
TABLE OF CONTENTS
PROJECT DESCRIPTION .................................................................................................................... 1
PREVENTATIVE BMP’s ..................................................................................................................... 1
INSPECTION ............................................................................................................................ 2
MAINTENANCE TASKS AND FREQUENCY ........................................................................................ 2
MAINTENANCE RESPONSIBILITY ..................................................................................................... 2
INSTRUCTIONS FOR MAINTENANCE CHECKLISTS ........................................................................... 2
MAINTENANCE STANDARDS FOR DRAINAGE FACILITIES ............................................................... 3
35072_Fed Way Plant 2 Relocation O&M_060922.doc
1
The maintenance requirements for this storm system and frequencies of each task are included
in this Operations and Maintenance (O&M) Manual.
PROJECT DESCRIPTION
The proposed project site is within a portion of the southeast quarter of the southeast quarter
of Section 20, Township 21 North, Range 4 East, W.M., City of Federal Way, Washington. The
parcels, 202104-9043, 202104-9155, 202104-9162, and 202104-9163, containing approximately
4.19 acres, are located at 35000 Pacific Highway South and are currently being used as a truck
storage facility. The project site is abutted by a commercial shopping center to the north and
east, Pacific Highway South (State Route 99) to the west, and a King County fire protection
facility to the south.
The existing parcels have three buildings and are covered predominantly with gravel and
asphalt paving with limited vegetation. The project site consists of a single Threshold Discharge
Area. Generally, runoff from the western half of the site flows to the west to the existing storm
conveyance system located within Pacific Hwy. S., and runoff from the eastern half of the site
flows to the south to the existing storm conveyance system located within S. 351st Street which
is then conveyed to the west to Pacific Hwy. S. Runoff from adjacent properties does not
appear to drain onto the project site.
A concrete batch plant is proposed on the project site. The majority of the site is proposing to
be paved for plant operation and parking areas and will also include a shop/storage building,
covered storage bins, concrete plant silos and equipment, and perimeter landscape buffer. Full
roadway improvements to S. 351st Street are proposed. The roadway is currently private but is
proposing to be built to public standards (Cross Section Type R) including 40 feet of pavement
with curb and gutter, 4 foot planter strip, and 6 foot sidewalk both sides.
The majority of the project site is providing oil control and enhanced basic water quality
treatment through the use of a coalescing plate oil/water separator, presettling vault, and
Oldcastle BioPod Biofilter. Water quantity control is proposed with an underground infiltration
vault. The western portion of the 351st Street improvements is unable to gravity flow to the
onsite storm facilities. This basin is proposing an Oldcastle Biopod Biofilter for water quality
treatment and will discharge to the existing conveyance system within Pacific Highway South.
Refer to Section 4 of the Technical Information Report for additional information regarding the
proposed storm systems.
PREVENTATIVE BMP’s
Catch basins are to have sumps to allow large particulate to settle without being introduced to
the main conveyance line. Also, the sumps will facilitate in maintaining and cleaning the system.
2
INSPECTION
Facility maintenance checklist sheets are contained in this manual. Drainage facilities shall be
maintained per King County requirements.
Specific maintenance schedule is difficult to anticipate at this time but it is recommend that
inspection of the facilities be worked into the regular schedule of the proposed site and other
general maintenance, in addition to inspections being made following larger less frequent
storm events. Proper correction to observed problems shall be as outlined in the following
excerpts from the King County Surface Water Design Manual (KCSWDM).
MAINTENANCE TASKS AND FREQUENCY
See attached Maintenance checklists.
Sediment and objects should be removed from catch basins when a depth of six (6) inches or
more has accumulated. Sediment and objects should be removed from pipes when a depth of
twenty (20) percent of the diameter of the pipe or more has accumulated. This maintenance
activity should be performed by professionals familiar with the proper disposal of hazardous
wastes.
MAINTENANCE RESPONSIBILITY
The property owner will be responsible for the maintenance of the storm system within the
site.
INSTRUCTIONS FOR MAINTENANCE CHECKLISTS
The following pages contain maintenance needs for the components that are part of the
drainage system, as well as for some components that may not be included. Ignore the
requirements that do not apply. Plan to complete a checklist for all system components on the
following schedule:
1. Monthly from November through April
2. Once in late summer (preferably September)
3. After any major storm (Use 1 inch in 24 hours as a guideline)
Using photocopies of these pages, check off and date the conditions looked for each time an
inspection was completed. Add comments on problems found and actions taken.
3
This O&M Manual/Checklist is to be kept on-site. It is suggested that photocopies of the
checklist should be kept in a binder and the checklists updated as required.
MAINTENANCE STANDARDS FOR DRAINAGE FACILITIES
The following pages contain maintenance standards for typical stormwater facilities that may
be required for stormwater mitigation. If the proposed stormwater system contains facilities or
components that are not listed, the owner is responsible for developing additional maintenance
standards and checklists for the proposed facility or component. Stormwater facilities and
components should be inspected as specified in the applicable maintenance standards.
The maintenance standards can be used as inspection forms for the system and associated
components. Record the date each time an inspection is completed and note any problems
and actions taken. Keep completed forms with the Operations and Maintenance Manual. City
staff may request to review the maintenance forms as a part of their inspection process. Some
components or facilities do not need to be looked at every time an inspection is conducted.
Use the suggested frequency at the left of each item as a guideline for activities to be
completed with each inspection.
The facility-specific maintenance standards contained in this section are intended to be
conditions for determining if maintenance actions are required as identified through inspection.
They are not intended to be measures of the facility’s required condition at all times between
inspections. In other words, exceeding these conditions at any time between inspections
and/or maintenance does not automatically constitute a violation of these standards.
However, based upon inspection observations, the inspection and maintenance schedules shall
be adjusted to minimize the length of time that a facility is in condition that required a
maintenance action.
MAINTENANCE REQUIREMENTS FOR FLOW
CONTROL, CONVEYANCE, AND WQ FACILITIES
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO. 2 – INFILTRATION FACILITIES
Maintenance
Component
Defect or Problem Conditions When Maintenance Is Needed Results Expected When
Maintenance Is Performed
Site Trash and debris Any trash and debris which exceed 1 cubic foot
per 1,000 square feet (this is about equal to the
amount of trash it would take to fill up one
standard size office garbage can). In general,
there should be no visual evidence of dumping.
Trash and debris cleared from site.
Noxious weeds Any noxious or nuisance vegetation which may
constitute a hazard to County personnel or the
public.
Noxious and nuisance vegetation
removed according to applicable
regulations. No danger of noxious
vegetation where County personnel
or the public might normally be.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Grass/groundcover Grass or groundcover exceeds 18 inches in
height.
Grass or groundcover mowed to a
height no greater than 6 inches.
Infiltration Pond,
Top or Side Slopes
of Dam, Berm or
Embankment
Rodent holes Any evidence of rodent holes if facility is acting
as a dam or berm, or any evidence of water
piping through dam or berm via rodent holes.
Rodents removed or destroyed and
dam or berm repaired.
Tree growth Tree growth threatens integrity of dams, berms
or slopes, does not allow maintenance access,
or interferes with maintenance activity. If trees
are not a threat to dam, berm, or embankment
integrity or not interfering with access or
maintenance, they do not need to be removed.
Trees do not hinder facility
performance or maintenance
activities.
Erosion Eroded damage over 2 inches deep where cause
of damage is still present or where there is
potential for continued erosion. Any erosion
observed on a compacted slope.
Slopes stabilized using appropriate
erosion control measures. If erosion
is occurring on compacted slope, a
licensed civil engineer should be
consulted to resolve source of
erosion.
Settlement Any part of a dam, berm or embankment that
has settled 4 inches lower than the design
elevation.
Top or side slope restored to design
dimensions. If settlement is
significant, a licensed civil engineer
should be consulted to determine
the cause of the settlement.
Infiltration Pond,
Tank, Vault, Trench,
or Small Basin
Storage Area
Sediment
accumulation If two inches or more sediment is present or a
percolation test indicates facility is working at or
less than 90% of design.
Facility infiltrates as designed.
Liner damaged
(If Applicable)
Liner is visible or pond does not hold water as
designed.
Liner repaired or replaced.
Infiltration Tank
Structure
Plugged air vent Any blockage of the vent. Tank or vault freely vents.
Tank bent out of
shape
Any part of tank/pipe is bent out of shape more
than 10% of its design shape.
Tank repaired or replaced to design.
Gaps between
sections, damaged
joints or cracks or
tears in wall
A gap wider than ½-inch at the joint of any tank
sections or any evidence of soil particles entering
the tank at a joint or through a wall.
No water or soil entering tank
through joints or walls.
Infiltration Vault
Structure
Damage to wall,
frame, bottom, and/or
top slab
Cracks wider than ½-inch, any evidence of soil
entering the structure through cracks or qualified
inspection personnel determines that the vault is
not structurally sound.
Vault is sealed and structurally
sound.
2016 Surface Water Design Manual – Appendix A 4/24/2016
A-3
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO. 2 – INFILTRATION FACILITIES
Maintenance
Component
Defect or Problem Conditions When Maintenance Is Needed Results Expected When
Maintenance Is Performed
Inlet/Outlet Pipes Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place.
Any open manhole requires immediate
maintenance.
Manhole access covered.
Locking mechanism
not working
Mechanism cannot be opened by one
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Mechanism opens with proper tools.
Cover/lid difficult to
remove
One maintenance person cannot remove
cover/lid after applying 80 lbs of lift.
Cover/lid can be removed and
reinstalled by one maintenance
person.
Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards.
Allows maintenance person safe
access.
Large access
doors/plate
Damaged or difficult
to open
Large access doors or plates cannot be
opened/removed using normal equipment.
Replace or repair access door so it
can opened as designed.
Gaps, doesn't cover
completely
Large access doors not flat and/or access
opening not completely covered.
Doors close flat; covers access
opening completely.
Lifting Rings missing,
rusted
Lifting rings not capable of lifting weight of door
or plate.
Lifting rings sufficient to lift or
remove door or plate.
Infiltration Pond,
Tank, Vault, Trench,
or Small Basin Filter
Bags
Plugged Filter bag more than 1/2 full. Replace filter bag or redesign
system.
Infiltration Pond,
Tank, Vault, Trench,
or Small Basin Pre-
settling Ponds and
Vaults
Sediment
accumulation
6" or more of sediment has accumulated. Pre-settling occurs as designed
Infiltration Pond,
Rock Filter
Plugged High water level on upstream side of filter
remains for extended period of time or little or no
water flows through filter during heavy rain
storms.
Rock filter replaced evaluate need
for filter and remove if not
necessary.
Infiltration Pond
Emergency
Overflow Spillway
Rock missing Only one layer of rock exists above native soil in
area five square feet or larger, or any exposure
of native soil at the top of out flow path of
spillway. Rip-rap on inside slopes need not be
replaced.
Spillway restored to design
standards.
Tree growth Tree growth impedes flow or threatens stability of
spillway.
Trees removed.
4/24/2016 2016 Surface Water Design Manual – Appendix A
A-4
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO. 4 – CONTROL STRUCTURE/FLOW RESTRICTOR
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Structure Trash and debris Trash or debris of more than ½ cubic foot which
is located immediately in front of the structure
opening or is blocking capacity of the structure
by more than 10%.
No Trash or debris blocking or
potentially blocking entrance to
structure.
Trash or debris in the structure that exceeds 1/3
the depth from the bottom of basin to invert the
lowest pipe into or out of the basin.
No trash or debris in the structure.
Deposits of garbage exceeding 1 cubic foot in
volume.
No condition present which would
attract or support the breeding of
insects or rodents.
Sediment Sediment exceeds 60% of the depth from the
bottom of the structure to the invert of the lowest
pipe into or out of the structure or the bottom of
the FROP-T section or is within 6 inches of the
invert of the lowest pipe into or out of the
structure or the bottom of the FROP-T section.
Sump of structure contains no
sediment.
Damage to frame
and/or top slab
Corner of frame extends more than ¾ inch past
curb face into the street (If applicable).
Frame is even with curb.
Top slab has holes larger than 2 square inches
or cracks wider than ¼ inch.
Top slab is free of holes and cracks.
Frame not sitting flush on top slab, i.e.,
separation of more than ¾ inch of the frame from
the top slab.
Frame is sitting flush on top slab.
Cracks in walls or
bottom
Cracks wider than ½ inch and longer than 3 feet,
any evidence of soil particles entering structure
through cracks, or maintenance person judges
that structure is unsound.
Structure is sealed and structurally
sound.
Cracks wider than ½ inch and longer than 1 foot
at the joint of any inlet/outlet pipe or any
evidence of soil particles entering structure
through cracks.
No cracks more than 1/4 inch wide at
the joint of inlet/outlet pipe.
Settlement/
misalignment
Structure has settled more than 1 inch or has
rotated more than 2 inches out of alignment.
Basin replaced or repaired to design
standards.
Damaged pipe joints Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
the structure at the joint of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of inlet/outlet pipes.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Ladder rungs missing
or unsafe
Ladder is unsafe due to missing rungs,
misalignment, rust, cracks, or sharp edges.
Ladder meets design standards and
allows maintenance person safe
access.
FROP-T Section Damage T section is not securely attached to structure
wall and outlet pipe structure should support at
least 1,000 lbs of up or down pressure.
T section securely attached to wall
and outlet pipe.
Structure is not in upright position (allow up to
10% from plumb).
Structure in correct position.
Connections to outlet pipe are not watertight or
show signs of deteriorated grout.
Connections to outlet pipe are water
tight; structure repaired or replaced
and works as designed.
Any holes—other than designed holes—in the
structure.
Structure has no holes other than
designed holes.
2016 Surface Water Design Manual – Appendix A 4/24/2016
A-7
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO. 4 – CONTROL STRUCTURE/FLOW RESTRICTOR
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Cleanout Gate Damaged or missing Cleanout gate is missing. Replace cleanout gate.
Cleanout gate is not watertight. Gate is watertight and works as
designed.
Gate cannot be moved up and down by one
maintenance person.
Gate moves up and down easily and
is watertight.
Chain/rod leading to gate is missing or damaged. Chain is in place and works as
designed.
Orifice Plate Damaged or missing Control device is not working properly due to
missing, out of place, or bent orifice plate.
Plate is in place and works as
designed.
Obstructions Any trash, debris, sediment, or vegetation
blocking the plate.
Plate is free of all obstructions and
works as designed.
Overflow Pipe Obstructions Any trash or debris blocking (or having the
potential of blocking) the overflow pipe.
Pipe is free of all obstructions and
works as designed.
Deformed or
damaged lip
Lip of overflow pipe is bent or deformed. Overflow pipe does not allow
overflow at an elevation lower than
design
Inlet/Outlet Pipe Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
Metal Grates
(If Applicable)
Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design
standards.
Trash and debris Trash and debris that is blocking more than 20%
of grate surface.
Grate free of trash and debris.
footnote to guidelines for disposal
Damaged or missing Grate missing or broken member(s) of the grate. Grate is in place and meets design
standards.
Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place.
Any open structure requires urgent
maintenance.
Cover/lid protects opening to
structure.
Locking mechanism
Not Working
Mechanism cannot be opened by one
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Mechanism opens with proper tools.
Cover/lid difficult to
Remove
One maintenance person cannot remove
cover/lid after applying 80 lbs. of lift.
Cover/lid can be removed and
reinstalled by one maintenance
person.
4/24/2016 2016 Surface Water Design Manual – Appendix A
A-8
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO. 5 – CATCH BASINS AND MANHOLES
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Structure Sediment Sediment exceeds 60% of the depth from the
bottom of the catch basin to the invert of the
lowest pipe into or out of the catch basin or is
within 6 inches of the invert of the lowest pipe
into or out of the catch basin.
Sump of catch basin contains no
sediment.
Trash and debris Trash or debris of more than ½ cubic foot which
is located immediately in front of the catch basin
opening or is blocking capacity of the catch basin
by more than 10%.
No Trash or debris blocking or
potentially blocking entrance to
catch basin.
Trash or debris in the catch basin that exceeds 1/3 the depth from the bottom of basin to invert
the lowest pipe into or out of the basin.
No trash or debris in the catch
basin.
Dead animals or vegetation that could generate
odors that could cause complaints or dangerous
gases (e.g., methane).
No dead animals or vegetation
present within catch basin.
Deposits of garbage exceeding 1 cubic foot in
volume.
No condition present which would
attract or support the breeding of
insects or rodents.
Damage to frame
and/or top slab
Corner of frame extends more than ¾ inch past
curb face into the street (If applicable).
Frame is even with curb.
Top slab has holes larger than 2 square inches
or cracks wider than ¼ inch.
Top slab is free of holes and cracks.
Frame not sitting flush on top slab, i.e.,
separation of more than ¾ inch of the frame from
the top slab.
Frame is sitting flush on top slab.
Cracks in walls or
bottom
Cracks wider than ½ inch and longer than 3 feet,
any evidence of soil particles entering catch
basin through cracks, or maintenance person
judges that catch basin is unsound.
Catch basin is sealed and is
structurally sound.
Cracks wider than ½ inch and longer than 1 foot
at the joint of any inlet/outlet pipe or any
evidence of soil particles entering catch basin
through cracks.
No cracks more than 1/4 inch wide at
the joint of inlet/outlet pipe.
Settlement/
misalignment
Catch basin has settled more than 1 inch or has
rotated more than 2 inches out of alignment.
Basin replaced or repaired to design
standards.
Damaged pipe joints Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
the catch basin at the joint of the inlet/outlet
pipes.
No cracks more than ¼-inch wide at
the joint of inlet/outlet pipes.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Inlet/Outlet Pipe Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
2016 Surface Water Design Manual – Appendix A 4/24/2016
A-9
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO. 5 – CATCH BASINS AND MANHOLES
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Metal Grates
(Catch Basins)
Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design
standards.
Trash and debris Trash and debris that is blocking more than 20%
of grate surface.
Grate free of trash and debris.
footnote to guidelines for disposal
Damaged or missing Grate missing or broken member(s) of the grate.
Any open structure requires urgent
maintenance.
Grate is in place and meets design
standards.
Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place.
Any open structure requires urgent
maintenance.
Cover/lid protects opening to
structure.
Locking mechanism
Not Working
Mechanism cannot be opened by one
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Mechanism opens with proper tools.
Cover/lid difficult to
Remove
One maintenance person cannot remove
cover/lid after applying 80 lbs. of lift.
Cover/lid can be removed and
reinstalled by one maintenance
person.
4/24/2016 2016 Surface Water Design Manual – Appendix A
A-10
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO. 6 – CONVEYANCE PIPES AND DITCHES
Maintenance
Component
Defect or Problem Conditions When Maintenance is Needed Results Expected When
Maintenance is Performed
Pipes Sediment & debris
accumulation
Accumulated sediment or debris that exceeds
20% of the diameter of the pipe.
Water flows freely through pipes.
Vegetation/roots Vegetation/roots that reduce free movement of
water through pipes.
Water flows freely through pipes.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Damage to protective
coating or corrosion
Protective coating is damaged; rust or corrosion
is weakening the structural integrity of any part of
pipe.
Pipe repaired or replaced.
Damaged Any dent that decreases the cross section area
of pipe by more than 20% or is determined to
have weakened structural integrity of the pipe.
Pipe repaired or replaced.
Ditches Trash and debris Trash and debris exceeds 1 cubic foot per 1,000
square feet of ditch and slopes.
Trash and debris cleared from
ditches.
Sediment
accumulation
Accumulated sediment that exceeds 20% of the
design depth.
Ditch cleaned/flushed of all
sediment and debris so that it
matches design.
Noxious weeds Any noxious or nuisance vegetation which may
constitute a hazard to County personnel or the
public.
Noxious and nuisance vegetation
removed according to applicable
regulations. No danger of noxious
vegetation where County personnel
or the public might normally be.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Vegetation Vegetation that reduces free movement of water
through ditches.
Water flows freely through ditches.
Erosion damage to
slopes
Any erosion observed on a ditch slope. Slopes are not eroding.
Rock lining out of
place or missing (If
Applicable)
One layer or less of rock exists above native soil
area 5 square feet or more, any exposed native
soil.
Replace rocks to design standards.
2016 Surface Water Design Manual – Appendix A 4/24/2016
A-11
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO. 17 – WETVAULT
Maintenance
Component
Defect or Problem Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Site Trash and debris Trash and debris accumulated on facility site. Trash and debris removed from
facility site.
Treatment Area
Trash and debris Any trash and debris accumulated in vault
(includes floatables and non-floatables).
No trash or debris in vault.
Sediment
accumulation
Sediment accumulation in vault bottom exceeds
the depth of the sediment zone plus 6 inches.
No sediment in vault.
Contaminants and
pollution
Any evidence of contaminants or pollution such
as oil, gasoline, concrete slurries or paint.
Materials removed and disposed of
according to applicable regulations.
Source control BMPs implemented if
appropriate. No contaminants
present other than a surface oil film.
Vault Structure Damage to wall,
frame, bottom, and/or
top slab
Cracks wider than ½-inch, any evidence of soil
entering the structure through cracks, vault does
not retain water or qualified inspection personnel
determines that the vault is not structurally
sound.
Vault is sealed and structurally
sound.
Baffles damaged Baffles corroding, cracking, warping and/or
showing signs of failure or baffle cannot be
removed.
Repair or replace baffles or walls to
specifications.
Ventilation Ventilation area blocked or plugged. No reduction of ventilation area
exists.
Inlet/Outlet Pipe Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
Gravity Drain Inoperable valve Valve will not open and close. Valve opens and closes normally.
Valve won’t seal Valve does not seal completely. Valve completely seals closed.
Access Manhole Access cover/lid
damaged or difficult to
open
Access cover/lid cannot be easily opened by one
person. Corrosion/deformation of cover/lid.
Access cover/lid can be opened by
one person.
Locking mechanism
not working
Mechanism cannot be opened by one
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Mechanism opens with proper tools.
Cover/lid difficult to
remove
One maintenance person cannot remove
cover/lid after applying 80 lbs of lift.
Cover/lid can be removed and
reinstalled by one maintenance
person.
Access doors/plate
has gaps, doesn't
cover completely
Large access doors not flat and/or access
opening not completely covered.
Doors close flat; covers access
opening completely.
Lifting Rings missing,
rusted
Lifting rings not capable of lifting weight of door
or plate.
Lifting rings sufficient to lift or
remove door or plate.
Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards.
Allows maintenance person safe
access.
2016 Surface Water Design Manual – Appendix A 4/24/2016
A-23
APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO. 23 – COALESCING PLATE OIL/WATER SEPARATOR
Maintenance
Component
Defect Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Site Trash and debris Any trash or debris which impairs the function of
the facility.
Trash and debris removed from
facility.
Contaminants and
pollution
Floating oil in excess of 1 inch in first chamber,
any oil in other chambers or other contaminants
of any type in any chamber.
No contaminants present other than
a surface oil film.
Vault Treatment
Area
Sediment
accumulation in the
forebay
Sediment accumulation of 6 inches or greater in
the forebay.
No sediment in the forebay.
Discharge water not
clear
Inspection of discharge water shows obvious
signs of poor water quality - effluent discharge
from vault shows thick visible sheen.
Repair function of plates so effluent
is clear.
Trash or debris
accumulation
Trash and debris accumulation in vault
(floatables and non-floatables).
Trash and debris removed from
vault.
Oil accumulation Oil accumulation that exceeds 1 inch at the water
surface in the in the coalescing plate chamber.
No visible oil depth on water and
coalescing plates clear of oil.
Coalescing Plates Damaged Plate media broken, deformed, cracked and/or
showing signs of failure.
Replace that portion of media pack
or entire plate pack depending on
severity of failure.
Sediment
accumulation
Any sediment accumulation which interferes with
the operation of the coalescing plates.
No sediment accumulation
interfering with the coalescing
plates.
Vault Structure Damage to Wall,
Frame, Bottom,
and/or Top Slab
Cracks wider than ½-inch and any evidence of
soil particles entering the structure through the
cracks, or maintenance inspection personnel
determines that the vault is not structurally
sound.
Vault replaced or repaired to design
specifications.
Baffles damaged Baffles corroding, cracking, warping and/or
showing signs of failure as determined by
maintenance/inspection person.
Repair or replace baffles to
specifications.
Ventilation Pipes Plugged Any obstruction to the ventilation pipes. Ventilation pipes are clear.
Shutoff Valve Damaged or
inoperable
Shutoff valve cannot be opened or closed. Shutoff valve operates normally.
Inlet/Outlet Pipe Sediment
accumulation
Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment.
Trash and debris Trash and debris accumulated in inlet/outlet
pipes (includes floatables and non-floatables).
No trash or debris in pipes.
Damaged Cracks wider than ½-inch at the joint of the
inlet/outlet pipes or any evidence of soil entering
at the joints of the inlet/outlet pipes.
No cracks more than ¼-inch wide at
the joint of the inlet/outlet pipe.
Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place.
Any open manhole requires immediate
maintenance.
Manhole access covered.
Locking mechanism
not working
Mechanism cannot be opened by one
maintenance person with proper tools. Bolts
cannot be seated. Self-locking cover/lid does not
work.
Mechanism opens with proper tools.
Cover/lid difficult to
remove
One maintenance person cannot remove
cover/lid after applying 80 lbs of lift.
Cover/lid can be removed and
reinstalled by one maintenance
person.
Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards.
Allows maintenance person safe
access.
2016 Surface Water Design Manual – Appendix A 4/24/2016
A-33
APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES
NO. 23 – COALESCING PLATE OIL/WATER SEPARATOR
Maintenance
Component
Defect Condition When Maintenance is Needed Results Expected When
Maintenance is Performed
Large access
doors/plate
Damaged or difficult
to open
Large access doors or plates cannot be
opened/removed using normal equipment.
Replace or repair access door so it
can opened as designed.
Gaps, doesn't cover
completely
Large access doors not flat and/or access
opening not completely covered.
Doors close flat and cover access
opening completely.
Lifting Rings missing,
rusted
Lifting rings not capable of lifting weight of door
or plate.
Lifting rings sufficient to lift or
remove door or plate.
NO. 24 – CATCH BASIN INSERT
Maintenance
Component
Defect or Problem Conditions When Maintenance is Needed Results Expected When
Maintenance is Performed
Media Insert Visible Oil Visible oil sheen passing through media Media inset replaced.
Insert does not fit
catch basin properly
Flow gets into catch basin without going through
media.
All flow goes through media.
Filter media plugged Filter media plugged. Flow through filter media is normal.
Oil absorbent media
saturated
Media oil saturated. Oil absorbent media replaced.
Water saturated Catch basin insert is saturated with water, which
no longer has the capacity to absorb.
Insert replaced.
Service life exceeded Regular interval replacement due to typical
average life of media insert product, typically one
month.
Media replaced at manufacturer’s
recommended interval.
Seasonal
maintenance
When storms occur and during the wet season. Remove, clean and replace or install
new insert after major storms,
monthly during the wet season or at
manufacturer’s recommended
interval.
4/24/2016 2016 Surface Water Design Manual – Appendix A
A-34
Inspection and Maintenance Guide
BIOPODTM SYSTEM
WITH STORMMIX™ MEDIA
BioPod™ Biofilter with StormMix™ Biofiltration Media
Description
The BioPod™ Biofilter System (BioPod) is a stormwater biofiltration treatment system used to remove pollutants
from stormwater runoff. Impervious surfaces and other urban and suburban landscapes generate a variety of
contaminants that can enter stormwater and pollute downstream receiving waters unless treatment is provided.
The BioPod system uses proprietary StormMix™ biofiltration media to capture and retain pollutants including
total suspended solids (TSS), metals, nutrients, gross solids, trash and debris as well as petroleum hydrocarbons.
Function
The BioPod system uses engineered, high-flow rate filter media to remove stormwater pollutants, allowing for a
smaller footprint than conventional bioretention systems. Contained within a compact precast concrete vault, the
BioPod system consists of a biofiltration chamber and an optional integrated high-flow bypass with a contoured
inlet rack to minimize scour. The biofiltration chamber is filled with horizontal layers of aggregate (which may or
may not include an underdrain), biofiltration media and mulch. Stormwater passes vertically down through the
mulch and biofiltration media for treatment. The mulch provides pretreatment by retaining most of the solids or
sediment. The biofiltration media provides further treatment by retaining finer sediment and dissolved pollutants.
The aggregate allows the media bed to drain evenly for discharge through an underdrain pipe or by infiltration.
Configuration
The BioPod system can be configured with either an internal or external bypass. The internal bypass allows both
water quality and bypass flows to enter the treatment vault. The water quality flows are directed to the biofiltration
chamber while the excess flows are diverted over the bypass weir without entering the biofiltration chamber. Both
the treatment and bypass flows are combined in the outlet area prior to discharge from the structure. BioPod
units without an internal bypass are designed such that only treatment flows enter the treatment structure. When
the system has exceeded its treatment capacity, ponding will force bypass flows to continue down the gutter to
the nearest standard catch basin or other external bypass structure.
The BioPod system can be configured as a tree box filter with tree and grated inlet, as a planter box filter with
shrubs, grasses and an open top, or as an underground filter with access risers, doors and a subsurface inlet
pipe. The optional internal bypass may be incorporated with any of these configurations. In addition, an open
bottom configuration may be used to promote infiltration and groundwater recharge. The configuration and size
of the BioPod system is designed to meet the requirements of a specific project.
Inspection & Maintenance Overview
State and local regulations require all stormwater management systems to be inspected on a regular basis and
maintained as necessary to ensure performance and protect downstream receiving waters. Without maintenance,
excessive pollutant buildup can limit system performance by reducing the operating capacity of the system and
increasing the potential for scouring of pollutants during periods of high flow.
Some configurations of the BioPod may require periodic irrigation to establish and maintain vegetation. Vegetation
will typically become established about two years after planting. Irrigation requirements are ultimately dependent
on climate, rainfall and the type of vegetation selected.
2
INSPECTION AND MAINTENANCE GUIDE
3
Maintenance Frequency
Periodic inspection is essential for consistent system performance and is easily completed. Inspection is
typically conducted a minimum of twice per year, but since pollutant transport and deposition varies from site to
site, a site-specific maintenance frequency should be established during the first two or three years of operation.
Inspection Equipment
The following equipment is helpful when conducting BioPod inspections:
• Recording device (pen and paper form, voice recorder, iPad, etc.)
• Suitable clothing (appropriate footwear, gloves, hardhat, safety glasses, etc.)
• Traffic control equipment (cones, barricades, signage, flagging, etc.)
• Manhole hook or pry bar
• Flashlight
• Tape measure
Inspection Procedures
BioPod inspections are visual and are conducted without entering the unit. To complete an inspection, safety
measures including traffic control should be deployed before the access covers or tree grates are removed. Once
the covers have been removed, the following items should be checked and recorded (see form provided on page 6)
to determine whether maintenance is required:
• If the BioPod unit is equipped with an internal bypass, inspect the contoured inlet rack and outlet chamber
and note whether there are any broken or missing parts. In the unlikely event that internal parts are broken
or missing, contact Oldcastle Stormwater at (800) 579-8819 to determine appropriate corrective action.
• Note whether the curb inlet, inlet pipe, or – if the unit is equipped with an internal bypass – the inlet rack is
blocked or obstructed.
• If the unit is equipped with an internal bypass, observe, quantify and record the accumulation of trash
and debris in the inlet rack. The significance of accumulated trash and debris is a matter of judgment.
Often, much of the trash and debris may be removed manually at the time of inspection if a separate
maintenance visit is not yet warranted.
• If it has not rained within the past 24 hours, note whether standing water is observed in the biofiltration
chamber.
• Finally, observe, quantify and record presence of invasive vegetation and the amount of trash and debris
and sediment load in the biofiltration chamber. Erosion of the mulch and biofiltration media bed should
also be recorded. Sediment load may be rated light, medium or heavy depending on the conditions.
Loading characteristics may be determined as follows:
o Light sediment load – sediment is difficult to distinguish among the mulch fibers at the top of the
mulch layer; the mulch appears almost new.
o Medium sediment load – sediment accumulation is apparent and may be concentrated in some areas;
probing the mulch layer reveals lighter sediment loads under the top 1” of mulch.
o Heavy sediment load – sediment is readily apparent across the entire top of the mulch layer; individual
mulch fibers are difficult to distinguish; probing the mulch layer reveals heavy sediment load under the
top 1” of mulch.
Often, much of the invasive vegetation and trash and debris may be removed manually at the time of inspection
if a separate maintenance visit is not yet warranted.
4
Maintenance Indicators
Maintenance should be scheduled if any of the following conditions are identified during inspection:
•The concrete structure is damaged or the tree grate or access cover is damaged or missing.
•The curb inlet or inlet rack is obstructed.
•Standing water is observed in the biofiltration chamber more than 24 hours after a rainfall event (use
discretion if the BioPod is located downstream of a storage system that attenuates flow).
•Trash and debris in the inlet rack cannot be easily removed at the time of inspection.
•Trash and debris, invasive vegetation or sediment load in the biofiltration chamber is heavy or excessive
erosion has occurred.
Maintenance Equipment
The following equipment is helpful when conducting BioPod maintenance:
•Suitable clothing (appropriate footwear, gloves, hardhat, safety glasses, etc.)
•Traffic control equipment (cones, barricades, signage, flagging, etc.)
•Manhole hook or pry bar
•Flashlight
•Tape measure
•Rake, hoe, shovel and broom
•Bucket
•Pruners
•Vacuum truck (optional)
Maintenance Procedures
Maintenance should be conducted during dry weather when no flows are entering the system. All maintenance
may be conducted without entering the BioPod structure. Once safety measures such as traffic control are
deployed, the access covers may be removed and the following activities may be conducted to complete
maintenance:
•Remove all trash and debris from the curb inlet and inlet rack manually or by using a vacuum truck as
required.
•Remove all trash and debris and invasive vegetation from the biofiltration chamber manually or by using a
vacuum truck as required.
•If the sediment load is medium or light but erosion of the biofiltration media bed is evident, redistribute
the mulch with a rake or replace missing mulch as appropriate. If erosion persists, rocks may be placed in
the eroded area to help dissipate energy and prevent recurring erosion.
•If the sediment load is heavy, remove the mulch layer using a hoe, rake, shovel and bucket, or by using a
vacuum truck as required. If the sediment load is particularly heavy, inspect the surface of the biofiltration
media once the mulch has been removed. If the media appears clogged with sediment, remove and
replace one or two inches of biofiltration media prior to replacing the mulch layer.
•Prune vegetation as appropriate and replace damaged or dead plants as required.
•Replace the tree grate and/or access covers and sweep the area around the BioPod to leave the site clean.
•All material removed from the BioPod during maintenance must be disposed of in accordance with local
environmental regulations. In most cases, the material may be handled in the same manner as disposal
of material removed from sumped catch basins or manholes.
Natural, shredded hardwood mulch should be used in the BioPod. Timely replacement of the mulch layer
according to the maintenance indicators described above should protect the biofiltration media below the
mulch layer from clogging due to sediment accumulation. However, whenever the mulch is replaced, the
BioPod should be visited 24 hours after the next major storm event to ensure that there is no standing water
in the biofiltration chamber. Standing water indicates that the biofiltration media below the mulch layer is
clogged and must be replaced. Please contact Oldcastle Infrastructure at (800) 579-8819 to purchase the
proprietary StormMix™ biofiltration media.
5
BioPod Tree Module BioPod Media Module
BioPod Planter Module BioPod Media Vault
6
Curb Inlet or Inlet Rack Blocked Notes:
Yes No
BioPod Inspection &
Maintenance Log
BioPod Model__________________________ Inspection Date________________________
Location______________________________________________________________________________
Condition of Internal Components Notes:
Good Damaged Missing
Standing Water in Biofiltration Chamber Notes:
Yes No
Trash and Debris in Inlet Rack Notes:
Yes No
Trash and Debris in Biofiltration Chamber Notes:
Yes No
Maintenance Requirements
Yes - Schedule Maintenance No - Schedule Re-Inspection
Invasive Vegetation in Biofiltration Chamber Notes:
Yes No
Sediment in Biofiltration Chamber Notes:
Light Medium Heavy
Erosion in Biofiltration Chamber Notes:
Yes No
BIOPODTM SYSTEM
WITH STORMMIX™ MEDIA
BUILDING
STRUCTURES
OUR MARKETS
TRANSPORTATION
WATER
ENERGYCOMMUNICATIONS
December 2018 v.1
www.oldcastleinfrastructure.com
800-579-8819