Surface Water Management

Facilities

Stormwater is precipitation that falls on hard surfaces that do not allow water to infiltrate. Stormwater facilities function to collect this water to slow it down and allow it to drop out pollutants before collecting with other natural waters like ground water, streams, lakes, and bays. These facilities are the only “treatment” rainwater gets before entering other waterways, unlike sewer and drinking water.

Stormwater facilities come in many forms throughout urbanized areas. They are often owned and maintained by Homeowners associations (HOA) or private landowners but can be owned publicly as well. Reach out to your HOA, look in your property deed or reach out to a local agency to learn more about facilities in your neighborhood.

Stormwater Management Manual for Western Washington

Types of Facilities

Surface Facilities

These facilities can look like open spaces or ponds, but they are actually working landscapes. For safety reasons, some are delineated by fencing, however, some are not that obvious. Recognizing when an open space is a stormwater facility and not a dog park or playground, ensures proper function of the system. These facilities can include:

Swales:

• Biofiltration Swale
• Bioretention cells
• Vegetated Filter Strips
  

Ponds

• Detention or dry pond
• Retention or wet pond
• Infiltration basin
• Treatment Wetland

Other

• Permeable pavers and pavement

Underground

These facilities operate below the surface, holding water to prevent overwhelming flows, catching sediment, and removing pollutants. These facilities are a junction for polluted runoff before it flows through pipes to natural waterways. These facilities typically present themselves as manhole covers and curb drains but they could also be below permeable cement in places like parking lots. Due to the confined spaces of these facilities, it is highly recommended to hire a contractor for maintenance. These facilities can include:

• Catch basin inlet/ manhole
• Drywell
• Vaults
  
  

Commercial

These facilities tend to be more specialize to the business needs. They can be more complex and require more attention to maintenance than residential systems. These facilities can include:

• Oil water separator
• Permeable pavers
• Sand filter

Maintenance

Routine maintenance is important to maintain your facility and avoiding expensive repairs. Private properties are responsible for maintaining their stormwater facilities.
Every facility should have a maintenance plan, someone in charge of managing that plan, and a record of all maintenance completed. Contact your local agency for regular inspections. Regular inspections and maintenance vary for different types of facilities. Maintenance plans should be based off all of the built features designated in the engineering plans.

Maintenance for Swales

• Routine trash and debris removal, especially during wet seasons
• Mowing and weed management
• Clear out sediment traps and/ or curb openings
• Look for standing water or bare spot that may indicate channel malfunction

Maintenance for Ponds

• Routine trash and debris removal, especially during wet seasons
• Mowing, weed management and tree removal
• Clear outlets and spillways of blockages and check for leaks
• Remove sediments as needed.

Maintenance for Permeable Pavements

• Routine sweeping and moss removal with a dry broom
• Refill aggregate between pavers as needed
• Replace broken sections
• Look for standing water

Maintenance for Underground Facilities
Contractor recommended due to confined spaces and their safety hazards.

LIST OF CONTRACTORS

Facilities may require specific contractors due to name brand system and parts

• Clear trash from inlets and outlets
• Vacuum and jetting with proper disposal of material
• Filter maintenance and replacement