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OPERATION AND MAINTENANCE MANUAL
FOR DRAINAGE FACILITIES
FOR
Carter Loop SE
City of Yelm, Washington
November 2024
Prepared for:
Projects West, Inc.
Prepared by:
Matthew Seawright, E.I.T., Project Designer
Approved By:
Daniel Smith, P.E., Senior Project Manager
REPORT #06141
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Project Description
The property is Tract D of Hawks Landing. The existing site coverage includes a single-family
residence, concrete sidewalk, and landscaping that is typically found in single-family
developments. The property has frontage along State Route 507, however access is only
proposed from Carter Loop SE. The project proposes to remove the existing site improvements
and subdivide the parcel into six (6) lots. Additionally, each proposed lot will allow for up to
4,500 sq.ft. of rooftops and up to 500 sq.ft. of driveway. Runoff from the future rooftops and
driveways will be infiltrated with infiltration trenches (BMP T7.20). All disturbed areas which
are not converted to impervious surfaces will have their soils amended per BMP T5.13).
Maintenance Importance
The importance of maintenance for the proper functioning of stormwater control facilities cannot
be over-emphasized. A substantial portion of failures (clogging of filters, resuspension of
sediments, loss of storage capacity, etc.) are due to inadequate maintenance. Stormwater BMP
maintenance is essential to ensure that BMPs function as intended throughout their full life cycle.
The fundamental goals of maintenance activities are to ensure the entire flow regime and
treatment train designed for this site continue to fully function. For this site these include:
Maintain designed stormwater infiltration capacity;
Maintain ability of storm facility to attenuate flow rates;
Maintain ability to safely convey design stormwater flows;
Preserve soil and plant health, as well as stormwater flow contact with plant and soil
systems;
Keep maintenance costs low;
Prevent large-scale or expensive stormwater system failures;
Prevent water quality violations or damage to downstream properties.
The intent of this section and manual is to pass on to the responsible party(s) all the information
critical to understand the design of the system, risks and considerations for proper use,
suggestions for maintenance frequencies, and cost so that realistic budgets can be established.
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Responsible Parties
Until such time that an HOA is established for the developer or declarant shall be the responsible
party for maintaining the stormwater facilities. The following is the current developer of the
project:
Developer: Projects West, Inc
Site Address: 15106 Carter Loop SE
Yelm, WA 98597
Tax Parcel Number: 52920000003
Ownership/Maintenance: Projects West, Inc
Legal description – Tract D of Plat of Hawks Landing as Recorded March 13, 2003
Under Auditor's File No. 3511261;
In Thurston County, Washington.
Facilities Requiring Maintenance
The project controls its runoff with on-lot infiltration trenches. A map of the project site is
included in at the end of this manual. The following are a list of facilities that require
maintenance:
Infiltration Trenches,
Plat landscaping.
Maintenance Instructions
The parties responsible for maintenance must review and apply the maintenance requirements
contained herein. These maintenance instructions outline conditions for determining if
maintenance actions are required, as identified through inspection. However, they are not
intended to be measures of the facility's required condition at all times between inspections.
Exceedance of these conditions at any time between inspections or maintenance activity does not
automatically constitute a violation of these standards. However, based upon inspection
observations, the inspection and maintenance presented in the checklists shall be adjusted to
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minimize the length of time that a facility is in a condition that requires a maintenance action.
For facilities not owned and maintained by the city, a log of maintenance activity that indicates
what actions were taken must be kept on site and be available for inspection by the city.
The operation and maintenance manual contains maintenance needs for most of the components
that are part of your drainage system, as well as for some components that you may not have.
Let City of Yelm know if there are any components that are missing from these pages. Ignore
the requirements that do not apply to your system. You should plan to complete a checklist for
all system components on the following schedule:
1. Monthly from November through April.
2. Once in late summer (preferably in September).
Using photocopies of the checklist pages check off the problems that you looked for each time
you did an inspection. Add comments on problems found and actions taken. Keep these
“checked” sheets in your files, as they will be used to write your annual report. Some items do
not need to be looked at every time an inspection is done. Use the suggested frequency at the left
of each item as a guideline for your inspection.
REQUIRED ACTIONS: The following actions shall be taken to ensure that pollution
generated on site shall be minimized:
1. Warning signs (e.g., "Dump No Waste-Drains to Groundwater") shall be painted or
embossed on or adjacent to all storm drain inlets. They shall be repainted as needed.
2. Sediment removed from the catch basins and storm system shall be disposed of in a proper
manner. Contact the City for instruction prior to completing this task.
Pollution Source Control Measures
See the Pollution and Source Control Manual for the Pollution and Source Control Plan.
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Vegetation Maintenance
Plant material affecting the storm water system consists of grass, leaves and yard debris. The
natural swale and interceptor ditch has water tolerant grasses which require cleaning and
mowing. Maintenance checklists on the following pages and instructions listed above address
appropriate maintenance requirements.
Annual Cost of Maintenance
The plat’s storm system consists mostly of on-lot infiltration trenches. On-lot infiltration
trenches are maintained by the homeowners.
REQUIRED ACTIONS: The following actions shall be taken to ensure that pollution
generated on site shall be minimized:
1. Roadways shall be swept when necessary to remove debris and, at a minimum, twice
a year. Use of newer model high-velocity vacuum sweepers is recommended, as they
are more effective in removing the more harmful smaller particles from paved
surfaces.
2. No activities shall be conducted on site that are likely to result in short-term high-
concentration discharge of pollution to the stormwater system. Such activities may
include, but are not limited to, vehicle washing, vehicle maintenance, and cleaning of
equipment used in the periodic maintenance of buildings and pave surfaces.
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MAINTAINANCE PROGRAM
COVER SHEET FOR CITY OF YELM
Inspection Period:
Number of Sheets Attached:
Date Inspected:
Name of Inspector:
Inspector’s Signature:
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