Private Stormwater Management Facilities

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A Public Works employee inspects a private stormwater management facility

The City of Hillsboro's Private Stormwater Management Facility Program includes the following components:

Inventory: Adding and tracking each facility in the City’s record management system
Inspection: Inspect and rate each facility for key performance indicators
Maintenance: Identify maintenance to perform
Education and Training: Provide information on effective maintenance

Maintenance Responsibilities

Private property owners are responsible for performing their own inspections, maintenance and repairs to their private stormwater management facilities. Each spring, the City sends annual notifications, by mail, as a reminder to perform maintenance on the facility.

The City has provided recommendations for the care and maintenance of vegetated stormwater facilities and filter catch basins, vaults, or detention systems.

Care and Maintenance for Vegetated Stormwater Facilities

Recommended Annual Inspection and Maintenance:

Check for winter storm damage, such as downed trees, and repair as needed.
Visually inspect all drains, pipe, and rock pads for damage or debris accumulation.
Remove weeds, problematic plants, and common invasive plants that can overwhelm the stormwater facility. Tualatin Soil and Water Conservation District common invasives list includes:
- Blackberries
- Reed Canarygrass
- Scotch broom
- Ivy
- Poison hemlock
Remove any garbage or accumulated debris, such as sediment, leaves, etc.
Replace dead treatment plants or shrubs as needed.
Inspect contributing private storm drains:
- Remove sediment and debris from surface grates.
- Remove debris within the storm drains annually.

Care and Maintenance for Filter Catch Basins, Vaults, or Detention Systems

Recommended Annual Inspection and Maintenance:

Conduct at least one visual inspection of the filters annually.
Clean and remove sediment and debris from all filter chambers or vaults annually and prior to replacing the cartridges.
Sediment and debris accumulation on or around the filter cartridges is an indicator that maintenance or filter replacement is required.
Cartridges that are halfway or more submerged without a recent rain event, such as rain with the last 2-3 days, indicates that maintenance or a filter replacement is required. Inspect contributing catch basins and storm drains at the site for damage or clogs.
Remove sediment and debris from surface grates.
- Debris within catch basins should be removed annually.
Filter vault and catch basin maintenance professionals can be found by visiting the filter manufacturer website.
Please have your contractor share the service and replacement records with the City - we will keep a file of the maintenance performed and reduce the need for additional site inspections.

Please contact us with any questions regarding your stormwater facility at Stormwater@Hillsboro-Oregon.gov.

For additional resources, see Clean Water Services list of maintenance activities by facility type.

Maintenance must not modify the facility or remove the required vegetation.
It is prohibited to use fertilizers, herbicides, pesticides, insecticides or other forms of chemical treatment within a private stormwater management facility.

Inspections

The City’s goal is to inspect 50% of all private facilities each year.
Property owners will be notified by mail of an upcoming inspection.
The CIty's contact information is included in the notice and property owners can contact the CIty to request to be present for the inspection.
Following the inspection, the City will provide details about any issues found and a rating of pass or fail.

Inventory

All private stormwater management facilities are inventoried at the time of initial construction and tracked in the City’s record management system. New or annexed facilities are also added into the system periodically.

How Stormwater Management Facilities Work

All stormwater facilities are designed to manage stormwater by removing most pollutants before stormwater enters natural drainage systems and impacts the health of local rivers and streams.

Four Types of Facilities

The City has four types of facilities:

Treatment Facilities: Remove pollutants from stormwater through natural filtration. Examples include vegetative swales, infiltration planters, rain gardens, filter strips, and green roofs.
Detention Facilities: Temporarily hold, infiltrate, and slowly release stormwater to reduce downstream flooding. Examples include detention ponds, water quality wetlands, and extended dry basins.
Proprietary Treatment and Storage Systems: Manage stormwater using manufactured filtration systems and storage chambers to temporarily store water underground.
Porous Pavement: Use underlying soil for infiltration and to reduce run-off. Examples include permeable pavers, concrete, and asphalt.

Private Maintenance Agreements

All new private stormwater facilities constructed in Hillsboro are required to complete and submit a Private Stormwater Management Facility Agreement for review. After review, please submit a final signed and notarized agreement.

The City signs and records the agreement with Washington County and provides a recorded copy to the owner.
Developers and property owners will be billed for recording costs.

For new development, or redevelopment, the agreement should be completed after the development review process and before the final inspection.

If you do not have a pre-existing agreement, please call us at 503-681-6146.