Construction activities can contribute excessive amounts of sediment into the public stormwater drainage system, lakes, streams, and wetlands. This can lead to the following problems:
- Pipes and ditches plugged by sediment are costly to clean, and can cause flooding and property damage.
- Excessive amounts of sediment in streams degrades aquatic habitat and inhibits salmon activities like predation and spawning.
- Excess nutrients in sediment cause growth of milfoil, algae, and other vegetation which decreases the recreational use and enjoyment of our waterways.
To protect sensitive areas and adjacent properties, development projects in the City of Kirkland are required to have a temporary erosion control plan containing tools to be used to limit the amount of sediment leaving the construction site. Only clean/clear stormwater can be allowed to enter the storm drains.
Construction sites must have erosion control inspections by City staff. The informational brochure, Small Parcel Erosion & Sediment Control (PDF), provides information on the small site erosion control inspection process.
Although erosion control tools may vary depending on site conditions, below are examples of a sample erosion control narrative and site plan:
Below are examples of erosion control tools:
- Limit the areas of disturbed activities
- Stabilized Construction Entrance
- Silt Fence
- Soil Cover (mulch, straw, plastic, etc.)
- Dust Control
- Ditches
- Check Dams
- Storm Drain Inlet Protection
- Compost Wattles/Berms
- Temporary Sediment Pond
Erosion control standard details are located with the City's Pre-approved Plans.
Dewatering
During construction, it may be necessary to pump groundwater or excess stormwater away from the site. This water can be contaminated with pollutants (including sediment) and cannot be discharged directly into the street or down a storm drain. The following dewatering options are available:
1) Pump the excess water to another area of the site, and allow it to infiltrate into the soil.
2) If infiltration is not possible, water can be temporarily be pumped to a storage facility (like a pond or tank) to allow settling prior to discharge to sanitary sewer. For specific requirements to discharge to sanitary sewer, refer to Information on Dewatering in Kirkland (PDF).
To report an erosion control problem, fill out the Drainage & Water Quality Report form.