2021 Kitsap County Stormwater Design Manual
2021 Kitsap County
Stormwater Design Manual

7.3 Operation and Maintenance Manual

An O&M Manual shall be submitted to the County as an appendix to the Drainage Report (Vol II–1.4.4 Drainage Reports). The O&M Manual shall provide O&M standards and guidelines for all proposed stormwater conveyance, On-Site Stormwater Management, Flow Control, and Treatment BMPs that are to be privately maintained. The O&M Manual shall be prepared by a professional engineer using plain language so it can be effectively followed by those persons who will be responsible for operating and maintaining the BMPs.

The following basic outline shall be followed in the preparation of the O&M Manual:

A. General Information:

  1. Purpose of O&M Manual – Briefly provide an introduction to the manual and a general statement on the overall purpose of operation and maintenance for each BMP.

  1. Basis of O&M Requirements – Identify the standards that were used to develop the O&M requirements. Incorporate information from the reference documents in Vol II–7.2.2 Maintenance Activities and Frequencies, as appropriate, and include any other reference documents that were used.

  2. Location and Access to BMP – Include the following:

    1. Name of stream/tributary/lake, etc., that BMP discharges to.

    2. Nearest cross streets.

    3. Traveling directions to BMP, including location of maintenance access roads.

    4. Vicinity map.

  3. Purpose of BMPs and Primary Performance Mechanisms – Document the primary purpose of BMPs and the key mechanisms for performing the primary purpose (e.g., conveyance for safe transport of stormwater runoff, peak flow rate reduction for flow control, infiltration for on-site stormwater management, filtration for treatment, sedimentation for treatment, etc.).

  4. General Description of BMPs – Describe BMP types (e.g., conveyance pipes, conveyance structures, bioretention swales, permeable pavement, etc.).

  5. Ownership – Include name, address, and telephone number of BMP owner.

  6. Project History – Identify the development for which BMP was constructed, date of construction, original project engineer and contractor, any significant modifications that have taken place during the life of the BMP.

  7. Project Data Sheet – List all major features of the BMP in an easy-to-follow tabular format, including catchment area, contributing hard surface area, offsite tributary drainage area, storage volume, design infiltration rates, orifice sizes, and designed release rates.

B. BMP Operation and Maintenance Plan:

The BMP O&M Plan provides detailed procedures required for routine and emergency O&M for all proposed stormwater BMPs (i.e., conveyance, On-Site Stormwater Management, Flow Control, and Treatment BMPs). This plan shall address the following components:

  1. Emergency Action Plan – Describe special operating procedures to be followed during emergency conditions, such as those resulting from extreme weather conditions or from structural or operational failure of the BMP. 24‑hour emergency contact telephone numbers must be included.

  2. Routine Maintenance – Identify maintenance tasks that shall be performed on a routine, regular basis. Describe the specific tasks and subtasks, staff and equipment needed, and frequencies for all maintenance activities.

  3. Triggered Maintenance – Identify maintenance activities that shall be conducted as-needed based on specified conditions or events, such as during or after storm events, flooding or water quality issues, or issues noted by staff during routine or triggered inspections. Specify the types of conditions that trigger the need for these maintenance activities and the specific tasks and subtasks, staff and equipment needed, and frequencies for all maintenance activities.

C. BMP Inspection Plan:

This section provides inspection checklists and an inspection report form to address the following components:

  1. Inspection Checklists – Include inspection checklists for all proposed stormwater BMP types, addressing:

    1. Routine Inspections – Identify routine visual inspection activities for the major features of the stormwater BMPs (i.e., inlets, outlets, infiltration areas, ponding areas, vegetated areas, etc.). Specify the staff and equipment needs and frequencies for all activities (e.g., weekly, monthly, etc.).

    2. Triggered Inspections – Identify inspection activities that shall be conducted on an as-needed basis, such as during or after storm events, to assess resident or business drainage complaints, or address staff observations during routine inspections. Specify the types of conditions or events that trigger the need for these inspections and the specific tasks or subtasks and staff and equipment needed.

  1. Inspection Report Form – Include a simple form to be completed by the person(s) performing the inspection that includes the date of inspection, the name of the person(s) performing the inspection, specific findings, follow-up actions needed, and the inspection checklist.