About this Pollution Prevention Plan
This is Skagit County’s model Construction Stormwater
Pollution Prevention Plan (“Construction SWPPP”) intended
to ensure your construction project minimizes erosion and
does not contribute pollution, including sediment, to
stormwater. This Model SWPPP is primarily intended for
single-family residential construction.
This plan uses certain Best Management Practices (“BMPs”)
from the Stormwater Management Manual. Some detailed
descriptions are included; the remainder are available at
www.skagitcounty.net/stormwaterpermitting. The listed
BMPs are the minimum necessary; if erosion occurs, you
must add additional BMPs as necessary to control it.
You should include your Construction SWPPP in your contract
with your builder. You must keep a copy of this SWPPP on the
construction site or within reasonable access to the site for
construction and inspection personnel at all times.
Property owners and contractors are responsible for ensuring
all aspects of BMPs are followed, including those not shown
on the detail sheets. This Construction SWPPP should be
considered a living document and must be updated as
needed to reflect site conditions.
Preserve Vegetation/Mark Clearing Limits
Before any land disturbance, including clearing and grading,
clearly mark all clearing limits, sensitive areas and their
buffers, and trees that are to be preserved within the
construction area. Retain natural vegetation in an
undisturbed state to the maximum extent practical. Use
• C101 to preserve natural vegetation
• C102 to establish buffer zones around important
vegetation you want to save
• C103 High Visibility Fencing to mark the boundaries of
• C233 Silt Fence to ensure sediment doesn’t leave the site
Establish Construction Access
Construction vehicles can damage or compact soils,
create sediment pollution, or track sediment onto public
All equipment and vehicles that access the construction area
must use an existing driveway or a stabilized construction
• Use BMP C105 Stabilized Construction Entrance wherever
traffic will be entering or leaving a construction site if
paved roads are within 1,000 ft of the site. Construct a 12-
inch thick pad of 4-inch to 8-inch quarry spalls, a 4-inch
course of asphalt treated base, or use existing pavement.
Place a separation geotextile under the spalls to prevent
fine sediment from pumping up into the rock pad. Install
the construction entrance prior to any vehicles entering
the site, at the location shown on the site plan. Create
only one construction entrance per site.
• Use BMP C103 High Visibility Fencing to restrict traffic to
the construction entrance.
• Remove any sediment that is tracked onto pavement by
shoveling or street sweeping, and remove the collected
sediment or stabilize it on site.
Control Flow Rates (not shown)
Stormwater on a cleared site can create significant
flows that can damage downstream properties.
Protect properties and waterways downstream of the project
site from erosion and the associated discharge of turbid
waters. If your project is required to control flow rates, you
must use the following BMPs as shown on the approved site
• C203 Water Bars
• C209 Outlet Protection
• C235 Straw Wattles
Install Sediment Controls
When land is devegetated, stormwater can pick up
sediment, a pollutant. BMPs can prevent sediment from
leaving the site.
You must install sediment controls before land disturbance to
effectively minimize and control the discharge of pollutants
Use and properly install BMP C233 Silt Fence. You must bury
the filter fabric as shown in the diagram in order for the BMP
to be effective. You must repair the silt fence if it is damaged.
Consider the following additional BMPs:
• C231 Brush Barrier
• C232 Gravel Filter Berm
• C234 Vegetated Strip
• C235 Straw Wattles
Note that C230 Straw Bale Barrier is no longer an approved
Leaving soils devegetated or exposed needlessly creates
erosion and sediment problems.
• Stabilize all exposed soils whenever construction work will
stop for more than two days at a time during the wet
season (October 1 to April 30) or 7 days the rest of the
year (the dry season).