HomeMy WebLinkAbout20250430_PWD3985_Operations Maintenance UOTECNNOl06'Es
LAND TECHNOLOGIES, INC.
PLANNING • PERMITTING • ENGINEERING
MAKING A"WAY"OUT OF"NO WAY"
Harmony at Arlington
7417 204th St NE., Arlington, WA 98223
April 2025
Operations &
Maintenance Manual
for
Harmony at Arlington
Prepared by:
Tyler Foster, P.E.
360-652-9727
Email:Tyler@landtechway.com
18820 Third Avenue NE,Arlington WA 98223 voice:360.652-9727 fax:360.652.7553
CONTENTS
Section1 - Introduction............................................................................................................................................3
1.1.1 Purpose....................................................................................................................................................3
1.1.2 Site Description........................................................................................................................................3
1.1.3 Maintenance Agreements.......................................................................................................................3
1.1.4 Obligations...............................................................................................................................................3
1.1.5 Scheduling................................................................................................................................................3
1.1.6 Activity Logs.............................................................................................................................................4
1.1.7 Record Keeping........................................................................................................................................4
1.1.8 Definitions &Terms.................................................................................................................................5
1.2 Facility Functions and Descriptions ................................................................................................................6
1.2.1 Catch Basin & Manholes..........................................................................................................................6
1.2.2 Debris Barriers (e.g.,Trash Racks)...........................................................................................................7
1.2.3 Rock Infiltration Trenches........................................................................................................................8
1.2.4 Downspout System..................................................................................................................................9
1.2.5 Bio-cell Facilities....................................................................................................................................10
Section 2—Inspection/ Maintenance Sheets........................................................................................................12
2.1 Contact Information .....................................................................................................................................12
Cityof Arlington..............................................................................................................................................12
Facilities Management: Owner/ Maintenance Personnel:......................................................................12
2.2 Amended Soils ..............................................................................................................................................13
2.3 Downspout System.......................................................................................................................................15
2.4 Control Structure Stand-Pipes......................................................................................................................17
2.4.1 Supplemental Maintenance Instructions for Bio-Cells (Rain Gardens).................................................18
2.5 Catch Basin & Manholes...............................................................................................................................19
2.6 Bioretention Cell Facility...............................................................................................................................22
2.7 Debris Barriers (e.g.,Trash Racks) ................................................................................................................25
2.8 Rock Infiltration Trenches.............................................................................................................................26
2.9 Access Roads.................................................................................................................................................27
2.10 Amended Soils Preparation and Specifications..........................................................................................29
2.10.1 Restoration Requirements for Disturbed Areas:.................................................................................29
2.11 Landscape Requirements............................................................................................................................30
2.11.1 General Maintenance..........................................................................................................................30
2.11.2 Specific Actions....................................................................................................................................31
2.11.3 Landscape Zones..................................................................................................................................31
2.11.4 Plant Recommendations......................................................................................................................32
2.11.5 Ground Cover.......................................................................................................................................32
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Section 1 - Introduction
1.1.1 Purpose
This manual provides guidelines and requirements for the maintenance and general upkeep of the stormwater
management BMPs and facilities as implemented as required by law.
The inspection, operation,and maintenance of the stormwater management facilities of the project is a legal
obligation pursuant to the City of Arlington.
1.1.2 Site Description
Harmony at Arlington - Harmony at Arlington LLC
7417 204th St NE, Arlington, WA 98223
1.1.3 Maintenance Agreements
Agreement to maintain facilities in accordance with City of Arlington and the Washington State Department of
Ecology's maintenance standards.
1.1.4 Obligations
Maintenance and operation of all drainage facilities located within the Site boundaries and outside of the right-
of-way is the responsibility of the home-owner's association and of the individual property owner. Drainage
facilities must be maintained and operated in accordance with the maintenance standards presented in this
document. All privately maintained flow control BMPs must be maintained as specified in the Site's/Lot's
declaration of covenant and grant of easement.
The City of Arlington may inspect all privately maintained drainage facilities for compliance with these
requirements. If the property owner(s)fails to maintain their facilities to the acceptable standards,the City may
issue a written notice specifying the required remedial actions and requiring a schedule for timely completion
of the actions. If these actions are not performed in a timely manner,the City may enter the property to
perform the actions needed and bill the property owner(s)for the cost of the actions. If a hazard to public
safety exists,the City may perform remedial actions without written notice.
A copy of this manual must be kept by an officer of the homeowner's association as well as any/all persons
involved with upkeep and operation and maintenance. This manual and all associated records must be
made available for inspection by the City of Arlington or an agent thereof.
1.1.5 Scheduling
The facility-specific maintenance standards contained in this manual 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, exceedance of
these conditions at any time between inspections and/or maintenance does not automatically constitute a
Harmony at Arlington O& M Manual April 2025 3 of 34
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 a condition that requires a
maintenance action.
In addition to the maintenance schedules, severe events, such as windstorms, flooding rains, construction or
vehicular accidents, seismic events, or the like, is cause for inspection. In the event of extensive damage,
reconstruction may be required, in which case, refer to the construction plan set in addition to this manual.
Key:
[M] Monthly from November through April.
[A] Annually, once in late summer(preferable September)
[S] After any major storm (use 1-inch in 24 hours as a guideline).
[B] Biannually (spring and fall)
[Q] Quarterly
[F] Observable failure of facility
1.1.6 Activity Logs
Reproduce the tables for each facility listed here for a maintenance activity log sheet to document any
inspection or maintenance of a facility.
1.1.7 Record Keeping
This section contains the inspection and maintenance sheets for the
various stormwater management BMPs and facilities. Copies of these
sheets are to be used for every inspection and/or service for each facility.
Make enough copies of each sheet for each facility for an annual service
cycle. Adhere to the following guidelines:
Provide one copy of sheet for each inspection or service.
All inspections or services must be documented and tracked via
these maintenance sheets.
The logged sheets are to be stored and kept with the facilities
manager
Inspect the facility(s) at the specified interval.
Use and fill out the inspection/maintenance sheet for each
inspection event.
Document and log any maintenance expenses as required.
Make back-up copies for your records.
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1.1.8 Definitions & Terms
Amended Soils Engineered soils that are a blend of soils with low to very low silt and clay content (sandy
soils)with a minimum of 10%organics materials (vegetative matter)to be used for
stormwater management.
BMP A Best Management Practice, as applied to stormwater management. This can be
physical device, such as a Rain Garden, or a procedure, such as placing the grasses and
vegetative matter along the downslope side and the underlying soils along the upslope
side while excavating a trench to minimize the chance of sediment laden runoff.
CB Catch basin. Typically a sub-surface concrete structure used in between pipes, often at a
bend location, or at the start of pipe.
Conveyance The process of moving stormwater runoff from one pace to another. This is typically
achieved by pipes, swales, or ditches.
Rock Bed A buried bed or'chamber' of clean angular rocks or stones,typically crushed rocks from a
quarry or gravel or aggregates supplier that have been washed or otherwise cleaned to
remove the fine particles (silt and clay). This bed is used for a temporary waters storage
facility where the water is held within the void spaces (air gaps between the rocks).
Facility A physical BMP that has been engineered to manage stormwater. This management
can be to regulate the rate of water release and/or to provide pollution control.
Impervious Surface Any hard surface that prevents or severely limits water from infiltrating into the soil.
Such examples are roof, concrete or asphalt paved areas, or highly compacted gravels or
soils that are high in silt and fines content.
Infiltration The process of water percolating or draining downward into the soil. This is often
measured as a rate with units of inches of standing water per hour.
Runoff Runoff or Stormwater runoff is the portion of rainwater that does not infiltrate into the
ground or is received by a stormwater management facility. This water runs over the
top of hard surfaces like roofs and roads, and when uncontrolled, can cause damage or
flooding.
Swale An engineered form of a ditch that is used to convey,treat, or infiltrate stormwater
runoff, or any combination of these facets depending on the design of the swale. The
swale is considered a facility.
Treatment The process of eliminating or reducing the pollutant content of stormwater runoff.
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1.2 Facility Functions and Descriptions
1.2.1 Catch Basin & Manholes
A catch basin (CB) is a sub-surface junction structure that typically has only one outlet pipe (where water exists)
and may have from zero to several pipes entering it. It has multiple functions. It is used at locations where
pipes must make a bend or where different pipe sizes or materials need to join. This allows pipes to remain
straight and be serviced. It may have a grated inlet at the top to collect surface runoff or a solid cover to
prevent runoff from entering. CBs fitted with a grate tops tend to be the part that required the most frequent
service, particularly where can be covered with leaves.
The CB structure is typically made of concrete. The CB can either be a Type 1 structure (a 2 foot by 2.5 foot)
rectangular box structure or a lager round, cylindrical structure with a minimum 4 feet diameter that is called a
Type 2 structure. These larger CBs are often referred to as a manhole as they are designed to allow a person
to climb into it for service reasons. They are also used for deeper and/or larger diameter pipes.
The 'catch' part of the basin name is either 1.5 foot or 2 foot deep (or deeper) sump designed to collect the
settling type of debris(sediment).
Grate Type Inlet
Collects water from
surface.
Flow Direction
Basin "sump"
or"catch''
CATCH BASIN (TYPE-A)
Inspection and maintenance tasks are described in Section 2.5.
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1.2.2 Debris Barriers (e.g., Trash Racks)
Trash rack or'debris screens' are used to prevent floating debris, animals, or other objects from either blocking
or entering the pipe system so that the pipes operation is not impeded. Smaller debris of a size that will not
cause blockage is able to pass through the 'screen'. Two types of debris barriers are used. The first is a bar
style 'trash rack' grate that covers the entrance of a pipe (culvert)that prevents larger debris from entering the
storm system. The second is a 'bird cage' style grate that covers and protects a vertical 'stand-pipe'.
Stand-pipe Debris Rack
Vertical Bar Atrium Grate
or Bar Guard Style
-
TRASH RACK FOR CATCH BASIN
I
I
I
TOP VIEW Pipe 3/4"0 Smooth Bars
coupling w/ends welded to
Bar-Frame SIDE VIEW
I
I
I
I
I �
Beveled End Section END VIEW °
SIDE VIEW
PIPE-END TRASH RACK
TOP VIEW
TRASH RACKS & DEBRIS SCREENS
Inspection and maintenance tasks are described in Section 2.7.
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1.2.3 Rock Infiltration Trenches
Rock infiltration trenches are rock filled trenches that accept stormwater through a pipe conveyance system.
The infiltration trench deposits stormwater into the native sand soil that is prevalent beneath the site and
surrounding area. Roof downspouts are the typical pipe system that is connected to the rock infiltration trench.
A series of perforated pipe conveys stormwater from the inlet to the rock. Cleanouts,filters, or catch basins
may be located at each end or in the midpoint of trenches. These prevent silt and sediment from reaching the
rock and clogging the system. These systems should be cleaned regularly to prevent clogging and ensure
functionality.
INFILTRATION DRY-WELL INSTALLATION DETAILS 18"Dia Yard CB (concrete pipe
1. Drywell bottoms must be a minimum of 1 foot above or HDPE N-12 or equivalent)in
seasonal high groundwater level or impermeable accordance with ASTM C-14.
soil layers(30 min expected on site). Use Solid Lid.
2. Each drywell may serve up to 1,000 square feet of
impervious roof surface. 4"Cap. Drill two 1"
3. Drywell to be 48 inches in diameter(minimum)and dia holes near top
have a depth of 5 feet(4 feet of rock and 1 foot of (opposite sides)
suitable cover material).
4. Avoid smearing soil surface at sides and bottom of
well. Scarify (rake)all surfaces prior to rock 12"
placement. `
5. Filter fabric(Tencate Mirafi 140-NL or equiv.
non-woven geotextile fabric)must be placed along 4"PVC or HDPE
sides of the dry well prior to rock placement and fold 12"
on top of rock prior to backfilling. (DWV)yard drain
6. Drain rock to be 1-1/2"to 3"clean drain rock(no (typ)
fines),clean RR ballast,or meet WSDOT Std spec
9-03.12(5)Gravel Backfill for Drywells. 18"min
7. Spacing between drywells must be a minimum of 6 Fine mesh Screen,
feet between side walls. 1/10"to 1/4"rust-poof
8. Downspout infiltration drywells must not be built on off'' • hardware cloth
slopes greater than 257o (4:1).Drywells may not be AF
placed on or above a landslide hazard area or
slopes greater than 15%without evaluation by a r6"min clean rock
professional engineer with geotechnical expertise or (as used in drwy-well)
a licensed geologist,hydrogeologist,or engineering
geologist,and with jurisdiction approval. DRY-WELL FILTER DETAIL
Roof Downspout
48"Dia Hole,Filled
House Drwy-well Filter with Drain Rock
per detail inset (See Note 6)
Flow b
PLAN
0
Roof Downspout �
--- Leaf Guard"Leaf Beater"with
-`ouse overflow(or equivvalent) Compacted Removable Plug or CAP,
L f Flush with Surface.
1-r- - Splash Block Topsoil w/fabric
over rock Locate in center of well.
Flow, b"solid wall pipeU
'min
5'Min
Min 4"Dio PVC4"-b"reducer
or DWV Pipe to 6"Tee)
5'Min**
6"perforated pipeDry-well Filter 8"min Dia Hole,
per detail inset Sides of Hole,Lined with— illed with Drain
Filter Fabric(See Note 5) ock(See Note b)
PROFILE 6"Solid Plug.Compact firmly into soil Min]'above
prior to fitment or use support plate. = Seasonal High
Groundwater
Table
302 DOWNSPOUT INFILTRATION DRYWELL
SCALE:NITS adapted per COB Std Detail D-41
Inspection and maintenance tasks are described in Section 2.3.
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1.2.4 Downspout System
The roof downspouts convey roof stormwater runoff to the infiltration trenches. This system is made up of
the roof gutters,the downspout pipes, and screens or filters for leaf or other debris removal. The system is
designed to deliver the roof stormwater runoff to the appropriate facility.
How it works
A primary screen enables the action of the water to
wash the screen and minimize maintenance.An
internal secondary stainless steel screen keeps ,
mosquitoes and vermin out of downpipes.
The elliptical outer screen can be adjusted to 4 different
angles faces to accommodate various rainfall intensities of and amounts of debris. After observing the i
performance of the filter,the screen can be adjusted '
until the best operating setting is achieved.
Installation
The Leaf Beater®is usually mounted directly under the
roof gutter,however it can be mid-mounted on a wall
to make it easier to access for cleaning.
RainHarvest Systems,LLC
http://www.rainharvest.com/filtration/pre-filtration/downspout-filters.asp DOWNSPOUT DEBRIS SCREEN
18"Dia Yard CB (concrete pipe
Roof Downspout or HDPE N-12 or equivalent) in
Drwy-well Filter accordance with ASTM C-14.
House Use Solid Lid.
per detail inset
Flow 4"Cap. Drill two 1"
dia holes near top
PLAN (opposite sides)
0
Roof Downspout 12"
Leaf Guard"Leaf Beater"with
overflow (or equivvalent) 4" PVC or HDPE
ouse Concrete Splash Block 12 (DWV) yard drain
to direct water away (typ)
from house and footings 18"min
.............
Fine mesh Screen,
1/10"to 1/4"rust-poof
FioW�, hardware cloth
Debris&Sediment Solid wall
pipe to 6" min clean rock
Filter per detail inset facility (as used in drwy-well)
PROFILE DRY-WELL FILTER DETAIL
DOWNSPOUT RUNOFF MANAGEMENT SYSTEMS
Inspection and maintenance tasks are described in Section 2.3.
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1.2.5 Bio-cell Facilities
The bio-cells (or Rain Gardens) are stormwater management facilities designed to collect runoff primarily from
the roadway and driveway areas of the plat, but they also collect some runoff from the yard areas. Being
engineered to provide very specific(metered) runoff treatment,they are referred to as 'bio-cells' rather than
'Rain Gardens'.
The bio-cell performs two primary jobs:
The first job is to collect and hold the stormwater runoff and release it to the main storm system at a steady
controlled rate. To do this,the bio-cell must be able to store water. There are three places water can be
stored: in the open ponding area at the surface of the bio-cell, in the pore space available in the engineered
soils (amended soils)that line the bio-cell, and in the pore space of a rock bed buried just below the soils.
Most of the water that enters the bio-cell filters down through the amended soils and infiltrates into the native
soils. Some systems fill an underlying rock bed if the site is situated on impermeable soils. A horizontal
perforated pipe within the rock bed, called the under-drain pipe, carries this filtered water to the vertical pipe
at the end of the bio-cell closest to the street. This vertical pipe is called the control structure standpipe and
it is 8 inches in diameter. Within this larger stand-pipe is a smaller pipe with a hole, or orifice, drilled at the
bottom of it. This pipe is called the orifice tube.The orifice tube blocks the outlet of the perforated pipe so
that water can only flow out slowly from the rock bed through the orifice.
When bigger storms arrive, especially storms that are back-to-back, all the space in the rock bed will be filled up
and the water will start to back up to the surface of the bio-cell. When storms are big enough or long enough,
the ponding area of the bio-cell will also fill up and water will start to flow out of the screened holes in the
cleanout standpipe, ensuring that all the available space in the rock storage area is used. Then, if water
continues to back up,the water will flow over the top of the control structure standpipe at the road end of the
bio-cell.
A second smaller vertical pipe is located at the other end of the bio-cell from the control structure stand pipe.
This second pipe is called the clean-out stand-pipe. It has a removable cap at the top, and it also has some
screened holes just below the cap.
The second job of the bio-cell is to filter or clean the water from the majority of the storms. To do this,the
amended soils and the various plants the line the bio-cell area employed. These provide numerous chemical,
biological, and physical actions in the soils that transform, remove, or retain pollutants from stormwater runoff.
The plants also provide additional flow control as they intercept and evaporate rainfall as well as uptake
moisture from the soils and transpire it. These functions are called "evapotranspiration".
Harmony at Arlington O& M Manual April 2025 10 of 34
Nootka Rose [S:2]
r i its�Ipl� iri Examples of plants appropriate for
FI Snowberry[S:2] different soil moisture zones in a
Thimbleberry[S.2]— - ';o -P> —Ernall Fr_.+,_,1 Bio—Retention or Rain Garden area
^� L ulbr u: E shown above. Code following name
Sunrose[C:3]� / [ ]
Pacific Bleeding Shrubby has format [Type:Zone]
Heart[P:3 �� Penstemon[P:3]
TloughSedge[E:i] � �� -- -t - PIi ,ba-I,[ Types:
Wild/Coastal T=tree
Strawberry[C:3] S=shrub
- 1 :- [E ] E=emergent
C=groundcover
�•�erl of Rush [E.I P=perennial
Nootka Rose [S:2] ack Twinberry [S 1] G=grass
Thimbleberry[S:2] Clustered Wild Rose[&]] Zones:
S:2 1 — wet
Snowberr
Sunrose[C:3] � Y[ ] 2 — moist
PacifShrubby 3 — dr
Bleedinlg� Penstemon[P:3] y
Heart[P:3] � y. �` Wild/Coastal Species may be substituted based
Strawberry[C:3] on nursery stock quality and
i r , - avoilibility. Refer to the DOE LID
116, Zone 3: Dryest Technical Guidance Manual for
II,_" Puget Sound, Appendix 3 for a
r 2: '_ess Wet plant list.
Grass Seed Mixes:—
Mix-1 in Zones 2,3
Mix-3 in Zone 1
BIO-IN FILTRATION CELL PLANTING SAMPLE
Inspection and maintenance tasks are described in Section 2.6.
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Section 2 — Inspection / Maintenance Sheets
2.1 Contact Information
City of Arlington
80 Columbia Avenue
Marysville, WA 98270
360-363-8100
www.marysvillewa.gov
Facilities Management: Owner/ Maintenance Personnel:
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2.2 Amended Soils
Name: Phone/Email: Date/Time Inspected:
Facility Location (CODE): Weather:
Maintenance Component Conditions When Maintenance Results Expected When Maintenance Is Describe work done -and/or-
Defect[Frequency] Is Needed Performed Observations and Notes
General
Soil media (maintain high Vegetation not fully covering Re-mulch landscape beds with 2-3 inches of
organic soil content) [A] ground surface. mulch until the vegetation fully closes over the
ground surface
Soil media (maintain high None. Preventative maintenance Return leaf fall and shredded woody materials
organic soil content) from the landscape to the site as mulch.
[Ongoing]
Soil media (maintain high None. Preventative maintenance On turf areas, mulch-mow or leave the clippings
organic soil content) (well distributed)to build turf health
[Ongoing]
Soil media (maintain high None. Preventative maintenance Avoiding broadcast use of pesticides(bug and
organic soil content) weed killers)like 'weed&feed',which damage
[Ongoing] the soil life.
Soil media (maintain high None. Preventative maintenance Where fertilization is needed (mainly turf and
organic soil content) [A] annual flower beds), a moderate fertilization
program which relies on natural organic fertilizers
(like compost)or slow release synthetic balanced
fertilizers.
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Maintenance Component Conditions When Maintenance Results Expected When Maintenance Is Describe work done -and/or-
Defect[Frequency] Is Needed Performed Observations and Notes
Compaction [A] Soils become waterlogged,do not To remediate,aerate soil,till or further amend
appear to be infiltrating. soil. If drainage is still slow, consider investigating
alternative causes(e.g., high wet-season
groundwater levels, low permeability soils).Also
consider land use and protection from compacting
activities. If areas are turf, aerate compacted
areas and top dress them with 1/4-1/2 inch of
compost to renovate them.
Erosion/scouring [A] Areas of potential erosion are Take steps to repair or prevent erosion. Identify
visible. and address the causes of erosion.
Grass/vegetation [A] Less than 75% of planted Take appropriate maintenance actions (e.g.,
vegetation is healthy with a remove/replace plants)
generally good appearance.
Noxious weeds [M] Listed noxious vegetation is See the Snohomish City noxious weed list. By
present. law, noxious weeds must be removed and
disposed immediately. It is strongly encouraged
that herbicides and pesticides not be used in
order to protect water quality.
Weeds [Q] Weeds are present. Remove and dispose of weed material.It is strongly
encouraged that herbicides and pesticides not be
used in order to protect water quality.
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2.3 Downspout System
Name: Phone/Email: Date/Time Inspected:
Facility Location (CODE): Weather:
Maintenance Results Expected When Maintenance Describe work done -and/or-
Component/Defect Conditions When Maintenance is Needed is performed Observations and Notes
[Frequency]
Downspout Pipe or Conduit
1 Conduit plugged, If downspout conduit is plugged, bent, or crimped or in
bent, or crimped any way hindered from delivering roof water to splash pad Cleaned or replaced down spout.
[A,F] or block.
Downspout Filter or Screen
2 Trash and Debris Trash and debris accumulated in or about the screen or filte No trash or debris from is present on or
Accumulation [B,F] blocking more that 40 percent of the filter area. around the filter.
Cleanout Stand-pipe or Yard CB
3 Flow appearing out Any flow from the top of cleanout stand-pipe is a sign of Blockage removed from downstream
of top of stand- blockage in the downstream portion of pipe. Down spout pipe or Splash Block replaced so water
pipe/cleanout. splash block is missing or moved from downspout outfall is channeled to rain garden or
or is cracked or broken, allowing water to saturate area dispersion area.
[M,F] near foundation.
4 Regular CB Sediment and/or floatable debris exists in sump of yard Clear debris and scoop or vacuum
Maintenance [B,F] catch basin. sediments from sump.
Conveyance Pipes
5 Obstructions, Use mechanical methods to remove
Including Roots [A] Root enters or deforms pipe, reducing flow. root if possible (pressure water jet).
Chemicals removal prohibited.
Rock Pad or Splash Blocks
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Maintenance Results Expected When Maintenance Describe work done -and/or-
Component/Defect Conditions When Maintenance is Needed is performed Observations and Notes
[Frequency]
6 Missing or Moved Only one layer of rock exists above native soil in area five Rock pad replaced to design standards.
Rock [A,F] square feet or larger, or any exposure of native soil where (put the rock back)
pad was originally installed.
7 Erosion [M,S] Soil erosion in or adjacent to block or rock pad. Rock pad replaced to design standards.
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2.4 Control Structure Stand-Pipes
Name: Phone/Email: Date/Time Inspected:
Facility Location (CODE): Weather:
Maintenance Results Expected When Maintenance is Describe work done -and/or-
Component/Defect Conditions When Maintenance is Needed performed Observations and Notes
[Frequency]
General
Any trash,debris, or leaves covering or No trash, debris, or leaves blocking the filter
partially blocking the filter cage (at top of stand-
p cage.
pipe)
1 Trash & Debris [M,F]
Trash or debris visible inside any portion of the Stand-pipe free of trash or debris.
stand-pipe.
2 Structure Damage Stand-pipe is visibly damaged in the form of Stand-pipe is vertical and free from any
Stand-pipe [M,F] cracks, holes, or leaning significantly(more visible damage.
than 15 degrees to any side).
3 Debris Cage (grate) Filter cage is visible deformed or missing Filter cage is straight and securely and
is damaged or squarely fastened to top of stand-pipe.
missing [M,F]
Underdrain Orifice Tube&Tube holder
4 Tube or holder Under-drain Tube holder is securely
Under-drain Tube or Tube Holder is damaged,
(inside standpipe) missing, or insecurely attached to inside wall of fastened to inside of stand-pipe and orifice
is damaged or stand-pipe tube is fully seated with hand-hold bolt fully
missing. [B,F] engaged within slot.
Orifice Tube cap is missing. Check for
5 Orifice Tube cap is any debris such as branch and leaf matter, Any debris found in tube is removed and
missing. stone or paper refuse is lodged at base of cap is secured in-place.
orifice tube.
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2.4.1 Supplemental Maintenance Instructions for Bio-Cells (Rain Gardens)
A Bio-detention Cell (or a Rain Garden) is a stormwater management flow control BMP (best management practice)that was installed to mitigate the
stormwater quantity and quality impacts of some or all of the impervious or non-native pervious surfaces on your property.
Bio-detention Cells are vegetated closed depressions or ponds that retain and filter stormwater from an area of impervious surface or non-native pervious
surface. Depending on soil conditions, rain gardens may have water in them throughout the wet season and may overflow (through the designated
overflow path such as a stand pipe or spillway) during major storm events.
The soil in the rain garden has been enhanced to encourage and support vigorous plant growth that serves to filter the water and sustain infiltration
capacity. The size, placement, and design of the rain garden as depicted by the flow control BMP site plan and design details must be maintained and may
not be changed. Plant materials may be changed to suit tastes, but chemical fertilizers and pesticides must not be used.
Mulch may be added and additional compost should be worked into the soil over time. Rain gardens must be inspected annually for physical defects. After
major storm events, the system should be checked to see that the overflow system is working properly. If erosion channels or bare spots are evident,they
should be stabilized with soil, plant material, mulch, or landscape rock. A supplemental watering program may be needed the first year to ensure the long-
term survival of the rain garden's vegetation.
Vegetation should be maintained as follows:
1 Replace all dead vegetation as soon as possible;
2 Remove fallen leaves and debris as needed;
3 Remove all noxious vegetation when discovered;
4 Manually weed without herbicides or pesticides;
5 During drought conditions, use mulch to prevent excess solar damage and water loss.
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2.5 Catch Basin & Manholes
Name: Phone/Email: Date/Time Inspected:
Facility Location (CODE): Weather:
Maintenance Component/ Results Expected When Describe work done -and/or-
Defect[Frequency] Conditions When Maintenance is Needed Maintenance is performed Observations and Notes
General
Trash or debris which is located immediately in front of the catch No Trash or debris located
basin opening or is blocking inletting capacity of the basin by immediately in front of catch basin
more than 10%. or on grate opening.
Trash or debris (in the basin)that exceeds 60 percent of the
sump depth as measured from the bottom of basin to invert of the No trash or debris in the catch
lowest pipe into or out of the basin, but in no case less than a basin.
1 Trash & Debris [B,F] minimum of six inches clearance from the debris surface to the
invert of the lowest pipe.
Trash or debris in any inlet or outlet pipe blocking more than 1/3 Inlet and outlet pipes free of trash
of its height. or debris.
Dead animals or vegetation that could generate odors that could No dead animals or vegetation
cause complaints or dangerous gases (e.g., methane). present within the catch basin.
Sediment(in the basin)that exceeds 60 percent of the sump
depth as measured from the bottom of basin to invert of the
2 Sediment[S,B,F] lowest pipe into or out of the basin, but in no case less than a No sediment in the catch basin
minimum of 6 inches clearance from the sediment surface to the
invert of the lowest pipe.
Top slab has holes larger than 2 square inches or cracks wider
than 1/4 inch
Top slab is free of holes and
3 Structure Damage to (Intent is to make sure no material is running into basin if not so cracks.
Frame and/or Top Slab designed).
[B,F]
Frame not sitting flush on top slab, i.e., separation of more than Frame is sitting flush on the riser
3/4 inch of the frame from the top slab. Frame not securely rings or top slab and firmly
attached attached.
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Maintenance Component/ Results Expected When Describe work done -and/or-
Defect[Frequency] Conditions When Maintenance is Needed Maintenance is performed Observations and Notes
Maintenance person judges that structure is unsound. Basin replaced or repaired to
design standards.
4 Fractures or Cracks in
Basin Walls/Bottom Grout fillet has separated or cracked wider than 1/2 inch and
[B,F] longer than 1 foot at the joint of any inlet/outlet pipe or any Pipe is re-grouted and secure at
evidence of soil particles entering catch basin through cracks. basin wall.
5 Settlement/ If failure of basin has created a safety,function, or design Basin replaced or repaired to
Misalignment [A,F] problem. design standards.
Vegetation g ind hL,nLinn mere than 100/ of tho
epeRing4G
basin opening-
6 Vegetation [13,F]
Vegetation grewiRg inlet/96itlet pipe nts that is More.than s
rhos toll and loss tho nhoc apart.
Any poisonous or nuisance vegetation which may constitute a
hazard to maintenance personnel or the public.
7 Contamination and Any evidence of noxious weeds as defined by State or local
Pollution [B,F] regulations. No pollution present.
(Apply requirements of adopted IPM policies for the use of
herbicides).
Catch Basin Cover
Cover is missing or only partially in place.Any open catch basin
8 Cover Not in Place [A,F] requires maintenance. Catch basin cover is closed
9 Locking Mechanism Not Mechanism cannot be opened by one maintenance person with Mechanism opens with proper
Working [B,F] proper tools. Bolts into frame have less than 1/2 inch of thread. tools.
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Maintenance Component/ Results Expected When Describe work done -and/or-
Defect[Frequency] Conditions When Maintenance is Needed Maintenance is performed Observations and Notes
10 Cover Difficult to One maintenance person cannot remove lid after applying normal Cover can be removed by one
lifting pressure. (Intent is keep cover from sealing off access to
Remove [B,F] maintenance person.
maintenance.)
Metal Grates (If Applicable)
11 Grate opening Unsafe Grate with opening wider than 7/8 inch. Grate opening meets design
[B,F] standards.
12 Trash and Debris Trash and debris that is blocking more than20%of grate surface
[B F] inletting capacity. Grate free of trash and debris.
13 Damaged or Missing. Grate missing or broken member(s)of the grate. Grate is in place and meets
[B,F] design standards.
Manhole
14 Cover Not in Place [F] Cover is missing or only partially in place.Any open manhole Manhole is closed.
requires maintenance.
15 Locking Mechanism Mechanism cannot be opened by one maintenance person with Mechanism opens with proper
Not Working [A,F] proper tools. Bolts into frame have less than 1/2 inch of thread tools.
(may not apply to self-locking lids).
Ladder
16 Ladder Rungs Unsafe Ladder is unsafe due to missing rungs, not securely attached to Ladder meets design standards
[A,F] basin wall, misalignment, rust, cracks,or sharp edges. and allows maintenance person
safe access.
17 Cover Difficult to One maintenance person cannot remove lid after applying normal Cover can be removed and
Remove [A,F] lifting pressure. Intent is to keep cover from sealing off access to reinstalled by one maintenance
maintenance. person.
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2.6 Bioretention Cell Facility
Name: Phone/Email: Date/Time Inspected:
Facility Location (CODE): Weather:
Maintenance Component/ Results Expected When Maintenance is Describe work done -and/or-
Defect[Frequency] Conditions When Maintenance is Needed performed Observations and Notes
Pooling Storage Areas
Any trash and/or debris which exceed 5 cubic
feet per 1,000 square feet(this is about equal to
the amount of trash it would take to fill up one
standard size garbage can). In general,there
1 Trash & Debris [B,F] should be no visual evidence of dumping. If less No trash or debris removed from site.
than threshold all trash and debris will be
removed as part of next scheduled
maintenance.
No sediment visible on the floor or sidewalls
of the bio-cell
2 Sediment [B,F] Sediment covers more than 30 percent of the (A percolation test pit or test of facility
floor area of the bio-cell bottom (pooling area) indicates facility is only working at 90%of its
designed capabilities. If two inches or more
sediment is present, remove).
Determine why grass growth is poor and
3 Poor Vegetation CoveragE When grass is sparse or bare or eroded correct that condition. Replant with plugs of
[B,F] patches occur in more than 10%of the swale grass from the upper slope: plant in the swale
bottom. bottom at 8-inch intervals. Or reseed into
loosened,fertile soil.
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Maintenance Component/ Results Expected When Maintenance is Describe work done -and/or-
Defect[Frequency] Conditions When Maintenance is Needed performed Observations and Notes
Mow vegetation or remove nuisance
When the grass becomes excessively tall vegetation so that flow not impeded. Grass
4 Vegetation, (greater than 10-inches);when nuisance weeds should be mowed to a height of 3 to 4 inches.
groundcovers [B,F] and other vegetation starts to take over. Remove grass clippings unless mulching
mower used as part of a regenerative
program for minimal pollutant loading area.
5 Vegetation, landscape See Supplemental Maintenance
[B,F]
Any of the following may apply: remove
6 Standing Water[M,F] When water stands in the swale between sediment or trash blockages, improve grade
storms and does not drain freely. from head to foot of swale, remove clogged
check dams(if applicable),
Any evidence of oil, gasoline, contaminants or Contaminants or pollutants
7 Contaminants and Pollutioi other pollutants. (Coordinate removal/cleanup are removed
with local water quality response agency).
Any evidence of rodent holes if facility is acting Rodents destroyed and dam or berm repaired.
8 Rodent Holes as a dam or berm, or any evidence of water (Coordinate with local health department;
piping through dam or berm via rodent holes. coordinate with Ecology Dam Safety Office if
pond exceeds 10 acre-feet.)
Eroded damage over 2 inches deep where Slopes should be stabilized using appropriate
cause of damage is still present or where there erosion control measure(s); e.g., rock
is potential for continued erosion. reinforcement, planting of grass, compaction.
9 Erosion on Side Slopes
Any erosion observed on a compacted berm
If erosion is occurring on compacted berms a
embankment. licensed civil engineer should be consulted to
resolve source of erosion.
Stand-pipes
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Maintenance Component/ Results Expected When Maintenance is Describe work done -and/or-
Defect[Frequency] Conditions When Maintenance is Needed performed Observations and Notes
10 Debris grate blocked or
damaged or standpipe See Control Structure Stand-pipe Maintenance
damaged [B,F]
Underdrain
11 Underdrain pipe plugged
with root, sediment, or Pond area fills more quickly and/or once filled, Use pressure-jet washer through cl . Pond
.
Remove orifice tube before cleaning. Po
debris. [inspect underdrai pond does not drain overnight.
should drain readily after storms.
orifice tube first] [B,F]
Repair or place missing or damage
12 Cleanout Stand-pipe [A,F] Missing or structural damage is apparent. components to standards presented in Plat
construction Plan set.
Emergency Overflow Spillway
Only one layer of rock exists above native soil
in area five square feet or larger, or any
13 Rocks Missing [A,F] exposure of native soil at the top of out-flow Rocks and pad depth are restored to design
standards.
path of spillway. (Rip-rap on inside slopes need
not be replaced.)
Repair or place missing or damage
14 Erosion [A,F] Missing or structural damage is apparent. components to standards presented in Plat
construction Plan set.
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2.7 Debris Barriers (e.g., Trash Racks)
Name: Phone/Email: Date/Time Inspected:
Facility Location (CODE): Weather:
Maintenance Results Expected When Maintenance is Describe work done -and/or-
Component/Defect Condition When Maintenance is Needed Performed Observations and Notes
[Frequency]
General
1 Trash and Debris Trash or debris that is plugging more than 20% of Barrier cleared to design flow capacity.
[B,F] the openings in the barrier.
Metal
2 Damaged/Missing Bars are bent out of shape more than 2 inches. Bars in place with no bends more than 3/4
Bars. [B,F] inch.
Bars are missing or entire barrier missing. Bars in place according to design.
Bars are loose and rust is causing 50%deterioration Barrier replaced or repaired to design
to any part of barrier. standards.
3 Inlet/Outlet Pipe Debris barrier missing or not attached to pipe Barrier firmly attached to pipe
[B,F]
Plastic
4 Damaged/Missing Bars are bent out of shape more than 1 inch or Replace Debris rack with equivalent item.
Bars. [B,F] missing bar.
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2.8 Rock Infiltration Trenches
Name: Phone/Email: Date/Time Inspected:
Facility Location (CODE): Weather:
Maintenance Results Expected When Maintenance is Describe work done -and/or-
Component/Defect Conditions When Maintenance is Needed Performed Observations and Notes
[Frequency]
Plastic or Wood Grade Board
1 Debris or
Vegetation More than 25%of width of overflow is blocked. Debris or Vegetation is cleared.
Blockage [B,F]
Rock Pad
2 Missing or Only one layer of rock exists above native soil in area
Moved Rock five square feet or larger, or any exposure of native Rock pad replaced to design standards.
[B,F] soil.
3 Erosion [B,F] Soil erosion in or adjacent to rock pad. Rock pad replaced to design standards.
4 Physical damage Structural damage caused by accidental or illicit Rock pad replaced to design standards,
[B,F] vehicle trespass, animal burrowing, or vandalism. outlet edge rebuilt to smooth level surface at
design elevation.
Cleanouts&Perforated Pipe
5 See Control Structur See Control Structure Stand-pipe
Stand-pipe See Control Structure Stand-pipe Maintenance Maintenance
Maintenance
Catch Basins
6 See Catch See Catch Basins See Catch Basins
Basins
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2.9 Access Roads
Name: Phone/Email: Date/Time Inspected:
Facility Location (CODE): Weather:
Maintenance Results Expected When Maintenance is Describe work done -and/or-
Component/Defect Conditions When Maintenance is Needed Performed Observations and Notes
[Frequency]
Site, general
Trash and debris exceeds 1 cubic foot per 1,000
square feet(i.e.,trash and debris would fill up one Roadway drivable by maintenance vehicles.
7 Trash and debris standards size garbage can).
[B,F]
Debris which could damage vehicle tires or prohibit Roadway drivable by maintenance vehicles.
use of road.
Materials removed and disposed of
8 Contaminants and Any evidence of contaminants or pollution such as according to applicable regulations. Source
pollution [B,F] oil, gasoline, concrete slurries or paint. control BMPs implemented if appropriate.
No contaminants present other than a
surface oil film.
Any obstruction which reduces clearance above Roadway overhead clear to 14 feet high.
road surface to less than 14 feet.
9 Block Roadway Any obstruction restricting the access to a 10-to
[B,F] 12 foot width for a distance of more than 12 feet or At least 12-foot of width on access road.
any point restricting access to less than a 10 foot
width.
Road Surface
10 Erosion,settlement,
potholes, soft Any surface defect which hinders or prevents Road drivable by maintenance vehicles.
spots, ruts [B,F] maintenance access.
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Maintenance Results Expected When Maintenance is Describe work done -and/or-
Component/Defect Conditions When Maintenance is Needed Performed Observations and Notes
[Frequency]
11 Vegetation on Trees or other vegetation prevent access to facility Maintenance vehicles can access facility.
Road Surface [B,F] by maintenance vehicles.
Shoulders and Ditches
12 Erosion [B,F] Erosion within 1 foot of the roadway more than 8 Shoulder free of erosion and matching the
inches wide and 6 inches deep. surrounding road.
Weeds and brush exceed 18 inches in height or Weeds and brush cut to 2 inches in height
13 Weeds and brush hinder maintenance access. or cleared in such a way as to allow
maintenance access.
Modular Grid Pavement(if applicable)
Materials removed and disposed of
14 Contaminants Any evidence of contaminants or pollution such as according to applicable regulations. Source
and pollution [B,F] oil, gasoline, concrete slurries or paint. control BMPs implemented if appropriate.
No contaminants present other than a
surface oil film.
15 Damaged or Access surface compacted because of broken on Access road surface restored so road
missing grid [B,F] missing modular block. infiltrates.
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2.10 Amended Soils Preparation and Specifications
2.10.1 Restoration Requirements for Disturbed Areas:
Disturbed areas are to be restored per the specifications of the Soils for Salmon BMP T5.13(See Snohomish County
Post-construction Soil Standard,Assistance Bulletin#94). The online document is currently available at:
www.co.snohomish.wa.us/documents/Departments/PDS/Bulletins/94SoiIStandardCombined1011.pdf
This BMP (Best Management Practice) provides four options for soil restoration:
• Option 1 - Leave undisturbed native vegetation and soil, and protect from compaction during
construction.
• Option 2 - Amend existing site topsoil or subsoil either at "preapproved" default rates, or at
custom calculated rates based on tests of the soil and amendment.
• Option 3 - Stockpile existing topsoil during grading, and replace it prior to planting. Stockpiled
topsoil must also be amended if needed to meet the organic matter or depth requirements,
either at a "pre-approved" default rate or at a custom calculated rate.
• Option 4-Import topsoil mix of sufficient organic content and depth to meet the requirements.
Of these, only Option 4 is feasible. If soil repair is required as a result of contamination such as silt and clay
content overload as a result of sedimentation or spill, or saturation of environmental pollutant overload, the
amended soils must be replaced and not further amended, hence only Option 4 is recommended.
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2.11 Landscape Requirements
Landscaping is part of the stormwater management system. As in nature,trees, shrubs and plants, and grasses
or ground-covers provide an important role in the hydrologic(water) cycle. Puget Sound sees an average
annual rainfall of about 40 inches per year. Nearly half of that evaporates in the natural condition. Most of
that is due to vegetation.
precipitation precipitation,
�}
� Evapo-transpiration �� � - Evapo-transpiration
Before 40-50q, After 20.301
less than 1`t. � �
surface Inte to
runoff
groun ate
�.' 0•
Before development, almost all rainfall is taken up by After conventional development, surface runoff
plants, evaporates; or infiltrates through the ground. increases significantly while evaporation and
Courtesy of Puget Sound Partnership infiltration into the ground decrease.
Plants do many other things, such as regulate air temperature, produce oxygen, provide habitat,filter the air,
and more. Upkeep of the plant in your yard not only improves the aesthetic and pride of ownership, it also
improves the environment. It is also part of the responsibility of homeownership.
2.11.1 General Maintenance
After heavy storms, check the inflow and overflow areas to make sure they are still intact and can continue to
carry water into and out of the rain garden. Remove any debris or litter in the rain garden that may interfere
with flow. Keep the inflow pipe accessible and flush out pipe if necessary. Look for areas where water may not
be soaking into the ground.This may be due to fine sediment or compaction of the soil. Remove sediment that
may be building up and rake the soil surface. If you suspect compaction, break up and loosen the soil when it is
not saturated.
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2.11.2 Specific Actions
• Maintain access to the bottom of the rain garden for weeding and other tasks. A few strategically placed flat
rocks can allow access to the bottom of the rain garden without compaction of the soil.
• Edging around the rain garden (such as pavers, stones, etc.) can facilitate access for maintenance and provide
separation from lawn and other landscaped areas.
• Maintain a healthy cover of plants.
• Remove any diseased plants or plant parts and dispose to avoid risk of spreading the disease to other plants.
• Disinfect gardening tools after pruning to prevent the spread of disease.
• Re-stake trees if they need more support, but plan to remove stakes and ties after the first year.
The majority of the following plant suggestions are borrowed from the "Rain Garden Handbook for Western
Washington",July 2013 version:
2.11.3 Landscape Zones
Rain gardens typically have three planting zones:
Zone 1 -the bottom of the rain garden which is the wettest area.
Zone 2-the side slopes, a periodically wet area.
Zone 3 -the perimeter area and/or on a berm, a drier soil area.
The following Table provides plant recommendation for maintenance and replacement plans spiciest.
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2.11.4 Plant Recommendations
TABLE 1 Bio-cell Plant List
ZONE 1
Emergents
Slough sedge (Carex obnupta) and smallfruited
Bulrush (Scirpus microcarpus)
Ferns
Lady fern (Athyrium filix-femina)
deer fern (Blechnum spicant)
Deciduous Shrub
Dwarf red-twig dogwood (Cornus sericea 'Kelseyi')
black twinberry (Lonicera involucrata) [larger areas]
ZONE 2
Ferns
Sword fern (Polystichum munitum) and
lady fern (Athyrium filix-femina)
Deciduous Shrubs
Snowberry (Symphoricarpos albus)
Evergreen Shrubs
Salal (Gaultheria shallon) and boxwood
Honeysuckle (Lonicera pileata)
ZONE 3
Herbaceous Perennials
Wild ginger (Asarum caudatum)
Insideout flower (Vancouveria hexandra), and
western bleeding heart (Dicentra formosa)
Ferns
Sword fern (Polystichum munitum)
Evergreen Shrubs
Evergreen huckleberry (Vaccinium ovatum)
low Oregon grape (Mahonia nervosa)
Deciduous Trees and Large Shrubs
Vine maple (Acer circinatum)
Cascara (Frangula purshiana)
Indian plum (Oemleria cerasiformis)
2.11.5 Ground Cover
For yard and ground cover, in and around the bio-cells, or for the road-side bio-swale areas,the following table
presents the recommended ground cover seed mixes.
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TABLE 2 Bio-Infiltration Swale and Filter Strip Seed Mixes
Species Percent Description
Hard Fescue Shade,drought and disease resistant. Grows in some of most adverse conditions and
45 heavily shaded areas. It is slow growing and low maintenance;left un-mowed it forms a
soft,4 to 6 inch carpet of grass.
Sheep Fescue Is a bunch grass that forms a soft carpet in a thick stand;requires little maintenance and
20 grows short(under a foot)needing little or no mowing(as described for lawn use). It is
very drought hardy. It suppresses weed growth and has heavy root growth protecting
against erosion.
Creeping Red Fescue Fescue that spreads by underground rhizomes allowing it to"fill-in"open areas. It is low
maintenance and shade tolerant. Used where low-input mowing,fertilization,and
10 irrigation is desired. Foliage does grow taller to 12"with 24"seed stalks. While taller
grass is not particularly desired;some Creeping Red Fescue is used to"fill-in"possible
bare areas created from bunch grasses.
Poa Supina Best shade grass on market. Has high wear tolerance with aggressive growth that out-
10 competes invasive species. Spreads by stolons forming a good"turf matt". Un-mowed
foliage height is 6 inches with seed head heights of 10 to 12 inches.
Dutch White Clover(prefer Clover is a legume that will provide nitrogen to the surrounding grasses. Typical Dutch
ProTime Microclover**, 15 White Clover only grows to 4 to 8 inches.The ProTime Microclover grows even lower
Trifolium repens "Pipolina") (rarely exceeds 6 inches)and is preferred due to its deeper stoloniferous root system
making it drought tolerant. Grows in shade or full sun.
Pre-Mix Options
Hobbs and Hopkins(503) ProTime 702 Low Profile Erosion Control Mix,genetically low growing and capable of
239-7518 100 forming dense root mass quickly. This mix uses Microclover and"tetraploid sheep
Portland Oregon fescue". Spread per mfg recommendations(typically 5lbs/1000 sf)
Agrivestment LTD(253)383-
5014 The Design mix should be spread at 4 to 5 Ibs/1000 sf.
Warehouse in Oregon Overseeding with Dutch White Clover should be%Ib/1000 sf.
(503)982-8655
**Available as single species from Nichols Garden Nursery www.nicholsgardennursery.com or
Hobbs and Hopkins in mix: www.protimelawnseed.com
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