Painted_Hills_O&M_Plan_-_PRD-04-21-20Page 1
OPERATIONS AND MAINTENANCE PLAN
FOR PAINTED HILLS PLANNED RESIDENTIAL
DEVELOPMENT FLOOD CONTROL SYSTEM & PLAT
AMENITIES
Abbreviations
PRD – Planned Residential Development
HOA – Homeowner’s Association
C.E.- Contracted Entity
COSV- City of Spokane Valley
OHWM- Ordinary High Water Mark
AHJ- Agency Having Jurisdiction
OSHA- Occupational Safety and Health Administration
Owner: Black Realty Inc.; or HOA as created via the Washington Secretary of State.
Party(s) responsible for Operations & Maintenance:
1) Black Realty Inc. until the formation of an HOA is complete.
2) Painted Hills PRD Homeowners Assn.
3) Contracted Maintenance Entity
4) Community Oversight – per CFR 65.6(a)(12) the City of Spokane Valley (COSV)
Manager or designee, and Spokane County Manager or designee (offsite facilities) will
be responsible for assuring that the maintenance activities are accomplished based on the
governing jurisdictional boundary.
Parent Parcel Number(s)-COSV: 45336.9191, 45334.0106, .0108, .0109, .0110, .0113, .0114, .9135,
44040.9144
LOCATED IN SECTION 33 & 34, T25N, R44E & SECTION 4, T24N, R44E, W.M.
SPOKANE COUNTY, WASHINGTON
The above parent parcels contain the Painted Hills PRD flood control drainage system.
The residential lot owners, commercial property owners and multi-family property owners of Painted
Hills PRD, are benefitting from these flood control facilities. The homeowner’s association of this
project, which is comprised of residential, multi-family and commercial lot owners, is responsible for
(details described later):
The continued operations and maintenance, including repair and replacement as needed, of these
facilities, see PRD Flood Control Plans.
Providing funds to finance the continued operation and maintenance of these facilities,
The administration of this agreement with each property owner within the PRD being bound by
this agreement and with the responsibilities to be shared equally between each Painted Hills PRD
property owner, (see fee schedule for applicable percentages) or contracted entity.
Establishing a maintenance committee and designating an HOA member to be responsible for the
administration of this plan,
Providing an annual report each October to Spokane Valley Public Works describing the general
status of the sinking fund account, and
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Providing an annual report each October to Spokane Valley Public Works describing specific
inspections, findings and maintenance performed, see checklist.
This operations and maintenance plan runs with the land and is binding upon the Painted Hills PRD
Homeowners Association property owners, their heirs, successors and assigns.
The parties mentioned above are primarily responsible for all operations and maintenance of facilities
mentioned herein and the administration of this plan.
Offsite Parcel Number(s)-County: 45336.9108 (Gustin Ditch), 45343.9052 (Triangle Pond)
LOCATED IN SECTION 34, T25N, R44E, W.M.
SPOKANE COUNTY, WASHINGTON
The above offsite County parcels are also a part of the Painted Hills PRD flood control drainage system.
The residential lot owners, commercial property owners and multi-family property owners of Painted
Hills PRD, are benefitting from these flood control facilities. The homeowner’s association of this
project, which is comprised of residential, multi-family and commercial lot owners, is responsible for
(details described later):
The continued operations and maintenance, including repair and replacement as needed, of these
facilities, see Gustin Pipe Plan set.
Providing funds to finance the continued operation and maintenance of these facilities,
The administration of this agreement with each property owner within the PRD being bound by
this agreement and with the responsibilities to be shared equally between each Painted Hills PRD
property owner, (see fee schedule for applicable percentages) or contracted entity.
Establishing a maintenance committee and designating an HOA member to be responsible for the
administration of this plan,
Providing an annual report each October to Spokane County Public Works describing the general
status of the sinking fund account, and
Providing an annual report each October to Spokane County Public Works describing specific
inspections, findings and maintenance performed, see checklist.
This operations and maintenance plan runs with the land and is binding upon the Painted Hills PRD
Homeowners Association property owners, their heirs, successors and assigns until such time as the
Gustin property (Parcel No. 45344.9108) develops and then the owner of that parcel will assume
responsibility for this plan. Parcel No. 45343.9052 (triangle pond) is covered by a storm drainage
easement granted to Spokane County as recorded in Book 659 Page 1803.
Spokane County assumes no responsibility at all for any operations or maintenance of the facilities
mentioned herein or the administration of this plan. Spokane County and the City of Spokane Valley and
their authorized agents are granted access rights for routine inspection and emergency repairs, but in
doing so incur no responsibility to perform these functions at any time.
1.00 PURPOSE
This plan is to provide:
1. General operations and maintenance responsibilities for the facilities described herein, and
2. Cost estimates of the assessments to be paid by each property owner mentioned herein for the
funding of this maintenance.
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2.00 GENERAL OPERATIONAL CHARACTERISTICS
Parent Parcel(s) Drainage Facilities-COSV
The Painted Hills PRD flood control drainage and existing Chester Creek system is intended to collect
and discharge stormwater runoff generated by upstream basins and stormwater from adjacent properties
as is identified on FEMA panel (53063C0751D, effective date July 6, 2010) as compensatory storage or
pass through storm flows. The PRD drainage facilities consist of a box culvert under Thorpe Road with a
concrete channel, headwall and trash rack, two 48” pipe mainlines between the box culvert and discharge
facility with another concrete headwall and trash rack at the outlet, WSDOT catch basins/manholes, a bio-
infiltration swale, settling pond with two 48” pipe outlets, headwall and trash rack (upstream, and
downstream), and a infiltration field/pond with associated drywells that receives runoff form the settling
pond. The system also includes 4-18” cross culverts under Madison Road that connect easterly of to the
two 48” pipe mainlines.
A portion of stormwater runoff from the upstream basins south of the project flows in the Chester Creek
channel under Thorpe Road continuing northwesterly under Dishman-Mica Road. This channel is also a
part of the system and will need to be maintained in conjunction with the City of Spokane Valley
The remainder of stormwater runoff from upstream basins south of the project flows under Thorpe Road
via the PRD box culvert then flows into the pipe system, through the grassed bio-infiltration swale and
into settling pond, until discharging into the infiltration pond at the north end of the site where the flow is
stored and infiltrated into the ground.
Stormwater runoff from upstream basins east of the project flows under Madison Road into 18” culverts
and outfalls into the two easterly 48” pipelines via WSDOT catch basins/manholes.
It is important to provide adequate maintenance activities to ensure that the flood control facilities remain
silt and debris free, as this silt and debris will affect their performance. Additionally, vegetation must be
maintained to prevent erosion of the system. Maintenance details are discussed below in Section 3.0.
Offsite Parcel(s) Drainage Facilities- County
The offsite County triangular pond located to the east of the Painted Hills project site (off of 40th Avenue
and west of Hwy. 27) is a part of the Whipple Consulting Engineers (WCE) Gustin Pipe Plan set. This
triangular pond and Gustin ditch are part of the County’s existing stormwater and floodplain system. The
improvements to this existing County storm system includes the addition of a 36” storm pipe running
parallel and within the existing Gustin Ditch, stormwater drywells, and a gravel access/maintenance road
to the pond bottom.
The existing Gustin Ditch (Parcel No. 45344.9108) is intended to collect and discharge stormwater runoff
into the triangle pond (Parcel No. 45343.9052) that is generated by upstream basins and from adjacent
properties as is identified on FEMA panel (53063C0751D, effective date July 6, 2010).
It is important to provide adequate maintenance activities to ensure that the flood control facilities remain
silt and debris free, as this silt and debris will affect their performance. Additionally, vegetation must be
maintained to prevent erosion of the system. Maintenance details are discussed below in Section 3.0.
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3.00 MAINTENANCE REQUIREMENTS AND SCHEDULES
All inspections and repairs are to be performed by or directly overseen by qualified professionals and
personnel (contracted entity) per this schedule and following major events. Maintenance tasks are to be
performed soon after the need is identified and before the facility is to perform unless otherwise agreed to
by the City or County for offsite drainage facilities. Repairs or replacements are to be completed
immediately upon their identification unless otherwise agreed to by the City or County. Only qualified
individuals may enter confined spaces and all OSHA rules must be followed. Major repairs or
reconstruction will need to be designed, approved, and inspected by professional engineers and the City
of Spokane Valley or Spokane County for applicable offsite facilities.
Parent Parcel(s) Drainage Facilities-COSV
The drainage facilities consist of several elements including: box culverts, existing Chester Creek
channel, storm drain mainline, culverts, outlet structure, bio-infiltration swale, inlet structure, infiltration
pond and associated drywells, manholes, catch basins, access roads, headwalls with trash racks, fencing,
and plant material. These elements are located as shown on the attached exhibit. The following describes
these facilities and the minimum required maintenance.
A comprehensive visual inspection of the complete PRD flood control drainage facilities should be
conducted twice a year. More frequent inspections for various elements may be required as described
below. For long duration storms, greater than 24 hours, the drainage facilities should be inspected during
the storm event to identify any developing problems and safely correct them before they become major
problems. Signs shall be posted notifying all residents to look for “potential” problems and to notify the
homeowners’ association of those observations.
In general, it is important to provide adequate maintenance activities to ensure that the vegetated areas
and structures remain silt, dirt and debris free because accumulations of these will affect the facilities
function for stormwater storage volume as well as the ability of the drywells and pond bottom to
discharge stormwater. Should these facilities silt up or become clogged, the flood control system will not
function as intended putting the PRD at risk of flooding. Therefore, periodic maintenance is a must.
Irrigation of Drainage Facilities-COSV
The Painted Hills PRD Homeowner’s Association and qualified personnel (contracted entity) shall ensure
that all drainage facilities are properly irrigated on a regular schedule to maintain and promote healthy
vegetation. Proper irrigation of vegetation is imperative to help to prevent erosion of channels, slopes, and
swale and pond bottoms. Personnel shall be careful not to overwater or erosion or excessive saturation
may result. This includes the roadside swales and/or landscape strip along Dishman Mica Road, Thorpe
Road, and Madison Road.
Box Culvert-COSV:
There are three box culvert crossings adjoining the project site; two are under Thorpe Road and one is
under Dishman Mica Road. These box culverts are within the public road right of way and will be
maintained by the agency having jurisdiction (AHJ) of the roadway. Any problems noticed while
inspecting or maintaining other elements of the system should be reported to the AHJ.
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LOCATION AGENCY HAVING JURISDICTION (AHJ)
Thorpe Rd near Madison Rd-Proposed City of Spokane Valley
Thorpe Rd near Dishman-Mica Rd-Existing City of Spokane Valley
Dishman-Mica Rd-Existing City of Spokane Valley
Chester Creek-COSV:
In addition to the instructions listed below, see Appendix B, Chester Creek, Operation & Maintenance
Manual from “Geotechnical Evaluation, Levee Evaluation and Certification, 4403 South Dishman-Mica
Road, Spokane County, Washington” prepared by Inland Pacific Engineering Company Project No. 14-
037, dated February 12, 2015, Revised August 29, 2016. As part of the project, stream buffer mitigation
impact areas are also necessary due to grading operations (fill) within the Chester Creek buffer area.
Maintenance of the required buffer mitigation areas are essential to restore and enhance the disturbed
riparian areas that provide a natural cover and provide food for native species; this will be accomplished
by re-establishing vegetation and by noxious weed control/reduction, and providing adequate irrigation
for healthy vegetative growth. For the complete report, including the planting schedule and guidelines for
planting and maintaining healthy vegetation in these mitigated areas, see the see the Biological
Evaluation, Critical Areas Report, and Habitat Management Plan for Painted Hills completed Larry
Dawes of Biology Soil & Water, Inc. provided in the Appendix (dated 02/28/19). It should be noted, that
some maintenance items listed below are taken directly from the above-mentioned report; mitigation
requirements listed below are also required for a minimum of five years if performance goals are met, or
until performance goals are met following the 5-year minimum requirement. The Performance goals are
listed in the maintenance items below, and the City of Spokane Valley and Larry Dawes of Biology Soil
& Water, Inc (or other professional Biologist) will determine if these goals have been satisfied after 5-
years. Annual maintenance of the mitigation areas should still continue after the required performance
goals are met, to ensure healthy vegetative growth and provide erosion control; however, the required
amount of vegetation and monitoring reports will not be stipulated or required by the City of Spokane
Valley.
Chester Creek extends across the southwest corner of the site from Thorpe Road northwesterly for
approximately 900 feet where it crosses under Dishman-Mica Road. The creek carries seasonal flows
from the foothills to the south. The site is protected from flood flows by an existing levee along the
northerly side of the creek and along the north side of Dishman-Mica Rd to Wilbur Rd. The intent of the
Painted Hills PRD fill project is to fill on the landward (north easterly) side existing levee, which will
provide further protection from flooding on the interior landward side of the painted Hills Development.
After the project is filled, the creek channel will need to be maintained to ensure flood carrying capacity
is not diminished. Maintenance of the channel, up to the Ordinary High Water Mark (OHWM) shall be
the responsibility of the City of Spokane Valley, while maintenance above the (OHWM) including
obtaining permits to perform the maintenance, shall be the responsibility of the Painted Hills PRD
Homeowner’s Association in coordination with the City of Spokane Valley.
Maintenance items (above the OHWM) include:
Regular mowing, grass should be kept at 3 inches or more in height but shall not exceed 12
inches, with the last mowing occurring to allow 8-10 inches of growth prior to winter
Removing trash, debris, noxious weeds plus items that reduce the amount of vegetative cover,
Removing any starts of woody vegetation that appear in the channel side slopes. Only native
grasses shall be used in the channel,
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Repairing any holes caused by burrowing animals and human activity such as utility work,
ORV’s or vandalism on the channel side slopes, traps for burrowing animals shall be used if
required,
Inspecting the channel side slopes making sure there are no breaches or breaks or erosion and
check for root and tree start invasion. Immediately repair with a sandy loess soil, compacted in
place, or bentonite type soil, and follow up after the storm event with seeding or sodding the
repair and more substantial maintenance activities if needed,
Repairing mowing damage,
Removing and replacing of the native grass and underlying soil if it becomes degraded to the
extent that the grass is not healthy and/or wilted,
Annually inspecting all mitigation areas to ensure re-establishment of vegetation in compliance
with the Biological Evaluation Report mentioned above,
Annually Inspecting the mitigation areas for noxious weed in the Spring to determine if the
previous year’s weed control measures were adequate, and to make preparations for the current
year accordingly,
Filling out the levee checklist and include the checklist in the annual report to the City.
Providing adequate irrigation for all required vegetative growth, especially for the Chester Creek
stream buffer mitigation impact areas,
Performance Goal-Ensuring herbaceous vegetations reaches 80% areal cover with native grasses
after five years, (year 1=20%, year 2=30%, year 3=50%, & year 5=80%) for buffer mitigation
areas,
Performance Goal -Ensuring a 100% survival of tree and shrub plantings and 80% survival every
year after for five years until performance goals are met for buffer mitigation areas,
Notifying the City of Spokane Valley (COSV) immediately if any observed functionality of the
mitigation areas is failing (unhealthy looking or wilting vegetation),
Storm Drain Mainline, Concrete Channel, Headwalls, and Trash Rack, and Outlet Pipes -COSV:
The storm drain mainline consists of 5,251 linear feet of 48” pipe from the downstream end of the new
box culvert at Thorpe Rd and Madison Rd, running parallel to Madison Rd and ending at the bio-
infiltration swale at the north end of the site. The bio-infiltration swale further outlets to the settling pond
that discharges to the large infiltration pond through (2)-48” outlet pipes that have concrete headwalls and
trash racks on the upstream and downstream side if the outlet pipes. The pipes need to be maintained to
prevent sediment and trash build-up in the bio-infiltration swale and the infiltration field/pond and
associated drywells. The concrete channel and associated headwalls and trash racks located downstream
of the Thorpe Road box culvert also needs to be inspected for physical integrity to prevent a breach/leak
in the channel or headwall and to ensure no obstructions are blocking the passage for stormwater, and to
prevent unauthorized entry into the storm system. Maintenance of the storm drain mainline shall be the
responsibility of the Painted Hills PRD Homeowner’s Association and/or the contracted entity (C.E.).
Maintenance items include:
Annually inspecting the pipe openings on each end to ensure there is no blockage or damage to
the ends,
Every three years or after substantial storm runoff, performing a TV inspection of the pipe
looking for blockages, damage, etc., visual inspection can be made at pipe manhole locations by
authorized maintenance personnel,
Removing sediment build-up from the pipe,
Repairing any sections of damaged pipe,
Visually inspecting twice a year the concrete channel, headwalls, and trash racks for damage or
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corrosion that would compromise the trash rack integrity.
Prior to each rainy season (August or September), inspecting each trash racks ensuring that there
is no debris present,
Following large storm events or rapid snow melt events performing a visual inspection and
remove any deleterious debris and trash,
Instructing those performing other maintenance functions on the system to report any observed
damage to the trash rack.
Catch Basins-COSV:
The mainline pipe system has WSDOT Type II catch basins at pipe junctions and angle points. Along
Madison Road there are catch basins connected by pipe to the mainline pipe system to drain overflow
from the roadside swales. Catch basins need to be maintained to prevent blockage of flow within the
system. Contact a professional or have the contracted entity remove the debris, trash and sediment
buildup, such as AAA Sweeping LLC. HOMEOWNERS ARE NOT TO ENTER THE
MANHOLES/CATCH BASINS. Maintenance of the catch basins shall be the responsibility of the
Painted Hills PRD Homeowner’s Association or the C.E.
Maintenance items include:
During routine landscape maintenance of roadside swales, removing any debris from catch basin
grates,
Annually inspecting catch basins for trash and sediment build-up and removing trash,
When sediment build-up fills ½ the depth of the sump (about 1 foot), removing the sediment,
Annually inspecting catch basin grates and lids to ensure they are properly seated and are
structurally sound,
Every five years, inspecting the structure walls to ensure the concrete walls are in good condition
and the joints remain sealed,
Instructing those performing other maintenance functions on the system to report any missing lids
or grates.
Cross Culverts (Flap Gates)-COSV:
The cross culverts consist of 18” CMP pipe crossing under Madison Road flowing from east to west in
four locations. The culverts connect into WSDOT Type II catch basins on the 48” storm drain mainline.
The cross culverts need to be maintained to prevent the reduction of seasonal flows within the pipes. The
reduction in flow may be caused by sediment or trash build-up within the pipe or obstruction of the pipe
entrance on the east side of Madison Rd. Maintenance of the cross culverts from the inlet up to, but not
including the flap gates shall be the responsibility the City of Spokane Valley. However, the flap gates
shall be the responsibility of the of the Painted Hills PRD Homeowner’s Association or the C.E.
Maintenance items include:
Annually inspecting the flap gates to ensure proper operation,
Every three years performing a TV inspection of the flap gates looking for blockages, damage,
corrosion, etc., and notifying the City of Spokane Valley if the pipes themselves need
maintenance,
Removing sediment build-up from the flap gates,
Repairing any sections or components of the flap gates.
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Bio-infiltration Swale/Channel, Roadside Swales, and Settling Pond-COSV:
The bio-infiltration swale/channel consists of a grass lined channel approximately 320 feet long with a 6-
foot bottom width and 2:1 side slopes and approximately 6-feet in depth. The swale needs to be
maintained to perform the function of removing any remaining contaminants including fugitive silts prior
to storm water entering the infiltration pond, with adequate irrigation provided for vegetation
establishment. Following the bio-infiltration channel is a settling pond to further reduce the sediment
loading in the infiltration pond. The settling pond then discharges to the large infiltration pond through
(2)-48” outlet pipes with headwalls and trash racks (see the Stormdrain Mainline Section on page 6 of this
report for inclusion of the outlet pipes, headwalls and trash racks). Additionally, roadside swales along
Dishman Mica Road, Thorpe Road, and Madison Road, require similar maintenance as the bio-infiltration
swale/channel that includes removing any sediment buildup or debris from the swales, and adequately
irrigating the swale to promote a heathy growth of grass. Maintenance of the bio-infiltration swale,
roadside swales, and settling pond shall be the responsibility of the Painted Hills PRD Homeowner’s
Association or the C.E.
Maintenance items include:
Annually inspecting the bio-infiltration swale/channel bottom and side slopes to ensure there is a
covering of grass, grass can be mowed no shorter than 8 to 10 inches, once annually,
Annually inspecting the settling pond bottom and side slopes to ensure there is a covering of
grass, grass can be mowed no shorter than 8 to 10 inches,
Removing accumulations of sediment that bury the grass cover for the channel, swales, and pond,
Reseeding any bare or dead areas of grass for the channel, swales, and pond,
Removing any noxious weeds within the channel, swales, and pond (spraying is acceptable),
Providing adequate irrigation for the bio-infiltration channel, swale, and pond (including side
slopes),
Annually inspecting the roadside swale bottoms and side slopes to ensure there is a covering of
grass, grass should be mowed in the same manner as residential home yards
Infiltration Field/Pond and Associated Drywells-COSV:
As previously mentioned, the infiltration pond receives runoff from the settling pond through (2)-48”
outlet pipes. The infiltration pond is comprised of 48-double depth drywells, and the drywells need to be
maintained to prevent or reduce sediment buildup in the drywell barrel so as to not reduce infiltration into
the surrounding ground. The infiltration field/pond bottom also needs to remain free of debris and
sediment build-up as it is the first point of infiltration. The Maintenance of the drywells and infiltration
pond shall be the responsibility of the Painted Hills PRD Homeowner’s Association or the C.E.
Maintenance items include:
Visually inspecting twice a year the inside of the drywell barrel(s) by removing the grate to look
into the structure. Have all debris and trash removed. Sediment must be removed before buildup
reaches the bottom of the lowest slot out of the drywell in the barrel wall. Contact a professional
to remove the debris, trash and sediment buildup. HOMEOWNERS ARE NOT TO ENTER THE
DRYWELL, as these drywells are 12-feet in depth with no internal ladder system.
Removing accumulations of sediment that bury the grass cover,
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Fencing-COSV:
The fencing of various system elements needs to be maintained to restrict access to those elements and to
protect the public. Maintenance of the fencing shall be the responsibility of the Painted Hills PRD
Homeowner’s Association or the C.E.
Maintenance items include:
Visually inspect twice a year the entire fencing system for damaged fence fabric, posts, gates,
signs, etc.
Prior to each rainy season (August or September), inspecting each access point ensuring that
locks and gates are functional.
Instructing those performing other maintenance functions on the system to report any observed
breaches or damage to the fencing.
Access Roads/Parking Pads-COSV:
The access roads/parking pads to various system elements need to be maintained to allow maintenance
vehicles access to those elements for periodic maintenance and emergency repairs to protect the public.
Maintenance of the access roads/parking pads shall be the responsibility of the Painted Hills PRD
Homeowner’s Association or the C.E.
Maintenance items include:
Visually inspecting annually, the entire access road/parking pad system for rutting, potholes, etc.
Regrade and repair with additional aggregate as needed.
Removing vegetation from the aggregate surface.
Instructing those performing other maintenance functions on the system to report any observed
damage to the access roads/parking pads.
Interior Asphalt Pathway, exterior Asphalt Pathway, and Concrete Sidewalk-COSV:
The interior asphalt pathway, the exterior asphalt pathway (Madison Road & Dishman Mica Road), and
concrete sidewalk (Dishman Mica Road & Thorpe Road) that provide pedestrian access around and
through the project site need to be maintained to allow safe pedestrian travel. Maintenance of the asphalt
pathways and concrete sidewalk shall be the responsibility of the Painted Hills PRD Homeowner’s
Association or the C.E.
Maintenance items include:
Visually inspecting annually, the entire pathway and sidewalk for rutting, potholes, cracking of
concrete or tree root intrusion, and repair or replace with additional asphalt or concrete as needed.
Removing vegetation or debris from the surface.
Instructing those performing other maintenance functions on the system to report any observed
damage to the asphalt pathway or concrete sidewalk.
Offsite Parcel(s) Drainage Facilities-County
The existing Gustin Ditch (Parcel No. 45344.9108) is intended to collect and discharge stormwater runoff
into the triangle pond (Parcel No. 45343.9052) that is generated by upstream basins and stormwater from
adjacent properties as is identified on FEMA panel (53063C0751D, effective date July 6, 2010).
Currently, stormwater runoff from the upstream basins is routed under Hwy 27 through a 36” culvert into
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the Gustin Ditch where the storm water flows to the west to the exiting pond. The improved drainage
system will consist of a 36” conveyance pipe running parallel and within the existing Gustin Ditch (Parcel
No. 45344.9108) to intercept the upstream basin stormwater. This existing flow will continue to discharge
to the existing triangle pond (Parcel No. 45343.9052) through the 36” storm outlet pipe. The triangle pond
will also have 18- stormwater drywells and a gravel road installed to provide access for maintenance to
the pond and stormwater drywells. These existing flows normally infiltrate into the existing pond bottom,
however, during larger storms the stormwater will overflow into the drywells and infiltrate into the
ground. The additional stormwater capacity provided by the drywells will capture and eliminate the
existing FEMA designated 100-Year Storm Event that would have theoretically continue to West if these
drywells were not installed.
A visual inspection of the drainage facilities should be conducted twice a year. For long duration storms,
greater than 24 hours, the drainage facilities should be inspected during the storm event to identify any
developing problems and safely correct them before they become major problems. It is important to
provide adequate maintenance activities to ensure that the drainage facilities remain silt and dirt free, as
this silt and dirt will affect their performance. Additionally, vegetation must be maintained to prevent
erosion of ditch and/or pond sides and to prevent flow restrictions within the ditch and/or pond from the
build-up of dead vegetation and tree and shrub invasion. Maintenance details are further discussed below.
Gustin Ditch with Pipe and Catch Basins-County:
The 36” PVC pipe needs to be maintained to ensure there is no debris or vegetation blocking the flow of
stormwater through the pipe. The pipe mainline has two 12” PVC cross culverts near the end of the pipe
mainline to further capture runoff from overland flow from the Gustin Ditch Property (Parcel No.
45344.9108). The ditch needs to be maintained to ensure a strong, healthy, dense vegetative cover and
that it is free of debris. Maintenance of the ditch and outfall shall be the responsibility of the Painted Hills
PRD Homeowner’s Association until such time as the Gustin property (Parcel No. 45344.9108) is
developed. At that time the owner(s) of the new development shall assume responsibility for maintenance
of the ditch and levee.
Maintenance items include:
Regular mowing, grass should be kept at 3 inches or more in height but shall not exceed 12
inches, with the last mowing occurring to allow 8-10 inches of growth prior to winter,
Removing trash, debris, noxious weeds plus items that reduce the amount of vegetative cover,
Removing any starts of woody vegetation that appear in the ditch. Only native grasses shall be
used to repair at removal areas,
Repairing any holes caused by burrowing animals and human activity such as utility work,
ORV’s or vandalism on the ditch side slopes,
Inspecting the ditch side slopes, and bottom making sure there are no breaches or breaks or
erosion and check for root and tree start invasion. Immediately repair with a sandy loess soil,
compacted in place and follow up after the storm event with seeding of the repair with native
grasses and more substantial maintenance activities if needed,
Repairing mowing damage,
Removal and replacement of the grass and underlying soil if it becomes contaminated to the
extent that the grass is not healthy.
Annually inspecting the pipe openings on each end to ensure there is no blockage or damage to
the ends,
Every three years or after substantial storm runoff, performing a TV inspection of the pipe(s)
looking for blockages, damage, etc., visual inspection can be made at pipe manhole locations by
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authorized maintenance personnel,
Removing sediment build-up from the pipe,
Repairing any sections of damaged pipe.
Catch Basins-County:
The Gustin Ditch pipe system has County Manholes (48” and 72” diameter) at pipe junctions and angle
points. Catch basins need to be maintained to prevent blockage of flow within the system. Contact a
professional or have the contracted entity remove the debris, trash and sediment buildup, such as AAA
Sweeping LLC. HOMEOWNERS ARE NOT TO ENTER THE MANHOLES/CATCH BASINS.
Maintenance of the catch basins shall be the responsibility of the Painted Hills PRD Homeowner’s
Association or the C.E.
Maintenance items include:
During routine landscape maintenance of roadside swales, removing any debris from catch basin
grates,
Annually inspecting catch basins for trash and sediment build-up and removing trash,
When sediment build-up fills ½ the depth of the sump (about 1 foot), removing the sediment,
Annually inspecting catch basin grates and lids to ensure they are properly seated and are
structurally sound,
Every five years, inspecting the structure walls to ensure the concrete walls are in good condition
and the joints remain sealed,
Instructing those performing other maintenance functions on the system to report any missing lids
or grates.
Triangle Pond & Drywells-County:
The pond bottom needs to be maintained to ensure there is no debris, vegetation or sediment preventing
the infiltration of storm water through the bottom of the non-irrigated pond. Also, that no debris,
vegetation or sediment buildup rise to a level that would allow it to enter into the drywells. Drywells need
to be maintained to prevent or reduce sediment buildup in the drywell barrel that would reduce infiltration
into the surrounding ground. Maintenance of the pond and drywells shall be the responsibility of the
Painted Hills PRD Homeowner’s Association until such time as the Gustin property (Parcel No.
45344.9108) is developed. At that time the owner(s) of the new development shall assume responsibility
for maintenance.
Maintenance items include:
Periodically visually inspect the grate and remove any deleterious debris and trash.
Biennially visually inspect the inside of the drywell barrel(s) by removing the grate to look into
the structure. Have all debris and trash removed. Sediment must be removed before buildup
reaches the bottom of the lowest slot out of the drywell in the barrel wall. Contact a professional
to vacuum out the debris, trash and sediment buildup. HOMEOWNERS ARE NOT TO ENTER
THE DRYWELLS.
Fencing-County:
The fencing around the triangle pond needs to be maintained to restrict access to those elements and to
protect the public. Maintenance of the fencing shall be the responsibility of the Painted Hills PRD
Homeowner’s Association or the C.E.
Page 12
Maintenance items include:
Visually inspect twice a year the entire fencing system for damaged fence fabric, posts, gates,
signs, etc.
Prior to each rainy season (August or September), inspecting each access point ensuring that
locks and gates are functional.
Instructing those performing other maintenance functions on the system to report any observed
breaches or damage to the fencing.
Access Roads/Parking Pads-County:
The access roads/parking pads to the triangle pond need to be maintained to allow maintenance vehicles
access to those elements for periodic maintenance and emergency repairs to protect the public.
Maintenance of the access roads/parking pads shall be the responsibility of the Painted Hills PRD
Homeowner’s Association or the C.E.
Maintenance items include:
Visually inspecting annually, the entire access road/parking pad system for rutting, potholes, etc.
Regrade and repair with additional aggregate as needed.
Removing vegetation from the aggregate surface.
Instructing those performing other maintenance functions on the system to report any observed
damage to the access roads/parking pads.
4.00 SINKING FUNDS
A sinking fund is an account that is set up to receive regular deposits which are to be used for paying off
future costs and debts. The sinking fund monies will be used to pay for planned and unplanned operation
and maintenance costs along with certain future replacement costs for the storm drainage facilities. The
sinking fund calculation should be revised as necessary to account for actual expenses and changes in
rates.
In setting up the fund, first the future replacement costs are estimated and then they are converted to
annual costs (or deposits) by the following calculations. These calculations assume that the inflation rate is
3% (for estimating the future replacement costs), the typical interest rate is 2% (for estimating the annual
costs) and the number of years before replacement is 20 (expect for buffer mitigation area replacement.
Equations and guidance for using other rates and years can be found in Appendix A.
1) Estimate the value that the item will have in the future when it is time to replace it using the
following equation:
FV=PV*1.8061, where: FV = future value
PV = present value
2) Estimate how much money will need to be deposited each year in a bank account in order to have
enough money accumulated in time to pay for the replacement using the following equation.
A=FV*0.0412, where: A = annual payment (or deposit)
FV = future value (from step 1, above)
Page 13
Sinking Fund Calculation Results:
The developer shall provide $95,000 to initiate the set-up of maintenance funds, and provide for one year
of maintenance.
The following values are the results of the calculations which are shown on the following page. The fund
calculations shall be updated once the actual cost of operation and maintenance items are contracted. As
contracts are renewed, the costs shall be adjusted accordingly.
Annual cost for regular operation and maintenance $152,392
Annual cost for replacements $76,979
Total annual costs $229,370
Total monthly costs (= total annual costs /12)$19,114.18
*Number of units (SF lots +MF lots) +(Commercial) 596+(18,400sf/100SF)=615
Monthly cost per lot (= total monthly costs /# lots)$31.08
Total annual cost per lot/unit $372.96
*Note: Number of units is based on 255-single family lots, 49 cottage units/lots, 240 apartment units, 52
mixed use apartment units, and 18,400 square feet of commercial building area divided by 1,000 square
feet (for an equivalent unit/lot).
Page 14 Sinking Fund Calculations-Parent Parcel(s)-COSVUnit Annual Price = CostComprehensive System InspectionEA2$1,000 $2,000 Drywell CleaningEA48 $500 $24,000 Catch Basin CleaningEA23 $300 $6,900 Mowing Channel EmbankmentsEA4 $2,000 $8,000 Mowing Roadside SwalesEA4 $2,000 $8,000 Debris Removal – culverts, catch basins, bio-swale, channels, drywells, manholesEA4 $2,000 $8,000 Channel/Trash Rack InspectionEA9 $500 $4,500 Pipeline TV Inspection – mainline, culverts, (3 years)LF5,750 $3 $17,250 Manhole/Catch Basin InspectionEA23 $100 $2,300 Fence, Access Road, Parking Area, Sign MaintenanceEA1 $500 $500 Swale & Pond Reseeding/Noxious Weed RemovalEA1 $500 $500 Reseeding/Noxious Weed Removal for buffer mitigation area EA1 $5,000 $5,000 1st Year Monitoring Report + ASBUILT ReportLS 1 $6,500 $6,500 Annual Monitoring Report (after 1st year)LS 1 $1,000 $1,000 Annual Report PreparationEA1 $1,500 $1,500 ContingencyLS1 20% $19,190 Total $115,140 REGULAR OPERATION AND MAINTENANCE COSTS-COSVDescriptionUnitsAnnual Quantity x
Page 15 UnitPrice =Drywell (48) (25%)EA 12 $10,000 $120,000 20 0.03 $216,733 0.02 $8,920 48” ADS N-12 HDPE pipeline (5,251) (25%) LF 1313 $150 $196,913 20 0.03 $355,646 0.02 $14,637 48” ADS N-12 HDPE culvert pipes (120 LF) (100%)LF 120 $150 $18,000 20 0.03 $32,510 0.02 $1,338 24” CMP pipeline (136) (100%)LF 136 $70 $9,520 20 0.03 $17,194 0.02 $708 18” PS46 ASTM F679 PVC (pipeline-future) (40) (100%)LF 40 $40 $1,600 20 0.03 $2,890 0.02 $119 15” Perforated HDPE (underdrain) (40) (100%) LF 40 $30 $1,200 20 0.03 $2,167 0.02 $89 12” SDR-35 ASTM D3034 PVC pipe to mainline(44) LF 44 $24 $1,056 20 0.03 $1,907 0.02 $78 12” CMP pipe to outfall (119) (100%)LF 119 $30 $3,570 20 0.03 $6,448 0.02 $265 WSDOT Catch basin, Type II (12)EA2 $4,500 $9,000 20 0.03 $16,255 0.02 $669 Catch basin, Type I (12)EA2 $1,500 $3,000 20 0.03 $5,418 0.02 $223 Infiltration & Settling Pond -seeding (189,644+7,172 )+ Roadsides Swale Seeding (49,187 ) + Landscape Strip Seeding (2,471 )SF 248474 $0.10 $24,847 20 0.03 $44,877 0.02 $1,847 Trash Racks (8) (100%)EA8 $2,000 $16,000 20 0.03 $28,898 0.02 $1,189 Signs (4) (25%)EA1 $200 $200 20 0.03 $361 0.02 $15 Buffer Mitigation Area (25%) of total cost of VegetationLS5 $6,785 $33,925 5 0.03 $39,328 0.02 $7,557 2” Asphalt pathway (9702 LF interor + 2,482 LF Madision Rd+ 822 LF Dishm. Rd)SY 14501 $10 $145,013 20 0.03 $261,910 0.02 $10,779 6” CSTC Access Rd (1,113 LF) (25%)CY 2087 $40 $83,480 20 0.03 $150,774 0.02 $6,205 Fencing (132 LF)LF 132 $35 $4,620 20 0.03 $8,344 0.02 $343 PC Concrete Sidewalk (Dishm.-356 LF+ 1356 LF Thorpe)SY 991 $36 $35,664 20 0.03 $64,413 0.02 $2,651 Total $57,635 REPLACEMENT COSTS-Parent Parcel(s)-COSV(for more information on calculations in this table see Appendix A)UnitsQuantity x Present Value, PVnInflation Rate, i1Future Value, FVInterest Rate, i2Annual Payment, A Notes: n = number of years to replacement LS means Lump Sum, EA means Each, SY means square yard, LF means Linear Feet, CY means Cubic Yards Quantity x is based on either a complete replacement (100%) or assumed 25% of the total rounded to the nearest whole number
Page 16 Sinking Fund Calculations-Offsite Parcel(s)-County Unit Annual Price = CostComprehensive System InspectionEA2$500 $1,000 Drywell CleaningEA 18 $500 $9,000 Manhole CleaningEA 9 $300 $2,700 Mowing Ditch EmbankmentsEA 4 $2,000 $8,000 Debris Removal – culverts, catch basins, pond ditch, drywells, manholesPipeline TV Inspection – mainline, culvertsLF 1,481 $3 $4,443 Manhole InspectionEA 9 $100 $900 Fence, Access Road, Parking Area, Sign MaintenanceEA 1 $500 $500 Pond Reseeding/Noxious Weed RemovalEA 1 $500 $500 ContingencyLS 1 20% $6,209 Total $37,252 EA 4 $1,000 $4,000 REGULAR OPERATION AND MAINTENANCE COSTS-COUNTYDescriptionUnitsAnnual Quantity x
Page 17 UnitPrice =Drywell (12) (25%)EA 12 $10,000 $120,000 20 0.03 $216,733 0.02 $8,920 36” PS46 ASTM F679 PVC pipeline (1441) (25%) LF 361 $150 $54,150 20 0.03 $97,801 0.02 $4,025 12” SDR-35 ASTM D3034 PVC pipeline (136) (100%)LF 136 $70 $9,520 20 0.03 $17,194 0.02 $708 Type I -48-County ManholeEA 2 $4,500 $9,000 20 0.03 $16,255 0.02 $669 72" County ManholeEA 5 $7,500 $37,500 20 0.03 $67,729 0.02 $2,788 Triangle Pond-seeding (17,060 SF) (100%)SF 17060 $0.10 $1,706 20 0.03 $3,081 0.02 $127 Signs (4) (25%)EA1 $200 $200 20 0.03 $361 0.02 $15 6” CSTC Access Rd (770 LF) (25%)CY 214 $40 $8,556 20 0.03 $15,452 0.02 $636 Fencing (560 LF) (100%)LF 560 $35 $19,600 20 0.03 $35,400 0.02 $1,457 Total $19,344 REPLACEMENT COSTS Offsite Parcel(s)-County (for more information on calculations in this table see Appendix A)UnitsQuantity x Present Value, PVnInflation Rate, i1Future Value, FVInterest Rate, i2Annual Payment, A
Page 18
IN WITNESS WHEREOF, the undersigned has reviewed the above information and determined it to be
appropriate for the improvements proposed for this plan and has caused this instrument to be executed on
this day of __________________________, 20____.
Signature:
Name (print):
Title:
STATE OF WASHINGTON )
COUNTY OF SPOKANE )
CITY OF SPOKANE VALLEY ) ss
I certify that I know or have satisfactory evidence that is/are
the individual(s) who personally appeared before me, and who acknowledged that he/she/they executed
and signed this instrument and acknowledged it to be his/her/their free and voluntary act for the uses and
purposes mentioned in this instrument.
Dated this __________ date of ______________________, 20____.
NOTARY PUBLIC
In and for the State of Washington,
Residing at
My appointment expires:
Page 19
Appendix A
The future replacement costs can be estimated and then converted to annual costs (or deposits) by the
following calculations.
1) Estimate the value that the item will have in the future when it is time to replace it using an
assumed (best estimate) inflation rate and the following equation:
FV=PV*(1+i1)n , where:
FV = future value i1 = inflation rate
PV = present value n = number of years to replacement
Example values for the factor: (1+i)n
n, years
5 10 15 20
i1 0.02 1.1041 1.2190 1.3459 1.4859
0.03 1.1593 1.3439 1.5580 1.8061
0.04 1.2167 1.4802 1.8009 2.1911
0.05 1.2763 1.6289 2.0789 2.6533
2) Estimate how much money will need to be deposited each year in a bank account in order to have
enough money accumulated in time to pay for the replacement using an assumed (best estimate)
interest rate and the following equation:
A=FV* i2 / [(1+i2)n-1], where:
A = annual payment i2 = interest rate
FV = future value n = number of years to replacement
Example values for the factor: i2/[(1+i2)n-1]
n, years
5 10 15 20
i2 0.02 0.1922 0.0913 0.0578 0.0412
0.03 0.1884 0.0872 0.0538 0.0372
0.04 0.1846 0.0833 0.0499 0.0336
0.05 0.1810 0.0795 0.0463 0.0302
Page 20
Appendix B – Chester Creek Channel, Operation & Maintenance
Manual
Modified from “Geotechnical Evaluation, Levee Evaluation and Certification, 4403 South
Dishman-Mica Road, Spokane County, Washington” prepared by Inland Pacific Engineering
Company Project No. 14-037, dated February 12, 2015, Revised August 29, 2016.
Page 21
CHESTER CREEK CHANNEL ABOVE THE
ORDINARY HIGH WATER MARK
OPERATION & MAINTENANCE
MANUAL
FOR
OPERATION AND MAINTENANCE
Painted Hills PRD Homeowners Association
IPEC Project No. 14-037
WCE Project # 13-1166
Updated January 2020
By
Inland Pacific Engineering Company
3012 North Sullivan Road
Building S-5, Suite C
Spokane Valley, WA 99216
&
Whipple Consulting Engineers
21 S Pines Road
Spokane Valley, WA 99206
Page 22
1.00 PURPOSE
This Operations and Maintenance manual is intended to provide general operations and
maintenance guidelines for the Chester Creek channel located at 4403 South Dishman-Mica
Road in Spokane County, Washington. The intent of the Painted Hills PRD project is to fill on
the landward (north easterly) side existing levee, which will provide further protection from
flooding on the interior landward side of the painted Hills Development. This O & M has been
amended from the original Chester Creek Levee O & M provided by Inland Pacific Engineering
Company. After the project is filled, the creek channel will need to be maintained to ensure flood
carrying capacity is maintained. Maintenance of the channel, up to the Ordinary High Water
Mark (OHWM) shall be the responsibility of the City of Spokane Valley. Maintenance above the
(OHWM) including obtaining permits to perform the maintenance, shall be the responsibility of
the Painted Hills PRD Homeowner’s Association in coordination with the City of Spokane
Valley. This general maintenance for the Chester Creek channel is inclusive whether in or out of
Spokane County public road rights-of-ways. Implementation of these guidelines will ensure that
the channel’s flood carrying capacity is maintained.
2.00 INTRODUCTION
The east side of the channel is typically at a 2.3:1 to 3:1 (H:V) slope. The land side of the channel is
also at a 3:1 slope from the Dishman-Mica Road bridge to approximately 300 feet southeast.
Between this point and Thorpe Road, the land side slope is much less and, in some areas, relatively
level with the crest. As mentioned above, the intent of the Painted Hills PRD project is to fill on
the landward (north easterly) side existing levee. This existing levee was constructed by the
previous landowner for the development of the golf course on the property and we believe it was
constructed in the early 1990’s by the property owner.
3.00 GENERAL OPERATION AND MAINTENANCE
3.10 Operation – During flood periods, the creek channel side slopes above the (OHWM)
should be patrolled to locate possible sand boils, unusual wetness of the landward slope, or
breaches. The inspector may look for indications of sliding or sloughing, that scouring action is
not occurring, that the channel is not being overtopped, and that no other conditions exist that
might adversely affect the integrity of the channel side slopes. Any damage or observed issues
below the (OHWM) should be reported to the City of Spokane Valley immediately.
Boils – A boil is a condition where enough pressure is produced by high water levels
so that water is piped through or under the channel bottom and channel side slopes
with sufficient velocity to carry earthen materials to the landward side of the channel.
If not controlled, these particles of earthen materials will be eroded from within the
channel, causing subsidence to the channel section. The continuation of this process
Page 23
may result in a break in the channel side slopes, allowing flood waters to flow over
the crest or through the channel side slopes.
Scour – Careful observation should be made of the creek channel side slopes to detect
potential erosion due to current action. Careful observation at the locations of bridge
structures should be made. In general, current velocities in Chester Creek are not
expected to cause significant scouring.
Creek Channel Topping – If the anticipated high-water level will exceeds the top
elevation of the channel , steps should be taken to provide emergency topping to raise
the channel side slope above forecasted water levels. These steps could include
sandbagging or hauling additional fill to raise the channel wall height.
3.11 A post-flood assessment of the creek channel side slopes above the (OHWM) should be
completed within 24 hours of the event. The assessment should document any damage to the
channel caused by flood waters. Any repairs necessary should then be completed after review
and evaluation of options. Any damage or observed issues below the (OHWM) should be
reported to the City of Spokane Valley immediately.
3.20 Maintenance – Maintenance activities for the creek channel above the (OHWM) are
described in this section. Below is a maintenance description for each of the elements affecting
channel conveyance performance.
Inspections – channel inspection should include a visual inspection of the channel
channel side slope sat a minimum of every 12 months for signs of erosion or
settlement. Preferably, the inspection should be completed in the fall prior to the
rainy season. The inspections should include the following:
o Unusual settlement, sloughing, or material loss of grade.
o Caving on both the creekside and landside of the channel which might
affect stability of the channel section.
o Seepage or saturated areas that may be occurring.
o Drainage in the creek is in good working condition facilities are not being
clogged.
o That the channel is shaped to drain properly to onsite Painted Hills PRD
drainage facilities.
o Ensuring that no unauthorized vehicles are located on the channel bottom
and channel side slopes.
o Rodent damage along the channel side slopes.
Erosion Protection – The channel side slope vegetation is a grass cover. The
grass should be mowed to a minimum height no shorter than 8 inches.
Page 24
No trees should be growing on the creek channel bottom or side slopes. No
excavations, structures, or other obstructions should be on the creek channel
bottom or side slopes.
Remove accumulation of drift, grass clippings, or other objectionable materials
from the creek channel side slopes.
Attached is a checklist for the annual or post-flood inspection.
Page 25
CHESTER CREEK CHANNEL
4403 SOUTH DISHMAN-MICA ROAD
SPOKANE COUNTY, WA
CREEK CHANNEL CHECKLIST (ABOVE THE OHWM ONLY)
Date: _______________________________________________________
Item Location and Description Action
Has the creek channel side
slopes settled or lost cross
section?
Has stream action caused any
slope washing or scouring?
Has there been any seepage or
saturated areas?
Has vegetation been
maintained?
Have weeds been removed?
Dates?
Condition of any riprap?
Have there been any authorized
or unauthorized encroachments?
Have burrowing animals been
exterminated/removed and the
creek channel channel side
slopes repaired?
Is the creek channel free of
obstructions and/or debris?
Are there any areas where the
creek is affecting the channel
side slopes?
Has there been any recent high-
water events?
Miscellaneous conditions:
Note: Use additional sheets as necessary.
Signed:
Title:
Page 26
Appendix C – Letter of Map Revision (LOMR)
To be inserted once completed.
WESNCSITE ELEMENT PLANC1.3JPP 1" = 200'N/AXDISHMAN-MICA RD.SPOKANE VALLEY,WADRAWN:PROJ #:REVIEWED:DATE:DATUM: NAVD - 8813-1166JOB NUMBERSHEETTRW13-116604/20/20WCETBM S-5 OF THE SOUTH PONDEROSA SEWER PROJECTWITH AN ELEVATION OF 2005.87 (NAVD29)=2009.67(NAVD88) WAS USED FOR THE VERTICAL DATUM FOR THISMAP.WHIPPLE CONSULTING ENGINEERS2528 NORTH SULLIVAN ROADSPOKANE VALLEY, WA 99216PH: 509-893-2617 FAX: 509-926-0227CIVILSTRUCTURALSURVEYINGTRAFFICPLANNINGLANDSCAPEOTHER SPOKANE VALLEY PAINTED HILLS PRDVERTICAL:HORIZONTAL:SCALE:REVISIONSNO. DATE BY 08-12-16JPP ORIGINAL PREPARATION1Reviewed for Conformance toStreet Standards andAccepted per Chapter 1.2Not ReviewedDate AcceptedAcceptance CommentsCity of Spokane ValleyDevelopment EngineeringCity of Spokane ValleyProject/Permit No.:SUB-2015-0001(Subdivision)FPD-2016-0007(Flood Plain Development)EGR-2016-0066(Engineered Grading)08-14-18JPP REVISED PLANS201-03-20JMH REVISED PLANS3DISHMAN-MICA ROADTHORPE ROADMADISON ROAD
40TH AVENUEHIGHWAY 27
WILBER ROAD
MADISON RD EASEMENT PLAN-