Erosion Control (silt fence)
Erosion control silt fence is the residential service that installs the temporary sediment fence required by Seattle SDCI and most King County jurisdictions on any disturbed residential lot over the size threshold — from $500 for a single 50-foot run to $1,800 for a full-lot perimeter with straw wattle add-ons. A homeowner pulls a permit for an addition and the inspector walks the property to a stop-work order until 80 feet of silt fence goes in. A driveway expansion churns up the front yard right before the rain returns and the runoff is heading straight for the storm drain. A new build is breaking ground in October and there is no erosion control on the contract. Handis installs silt fence to WSDOT Standard Specification 9-14.5 — the spec the inspector reads from — so the lot passes on the first walk instead of the third.
Service
What Does an Erosion Control Silt Fence Install Include?
A Handis silt fence install is the residential service that puts up the temporary sediment fence required on most disturbed residential lots over the jurisdictional size threshold — five families of work, all built to the spec the inspector reads from, all priced for honest residential lot sizes. Pricing starts at $500 for a single 50-foot run (the smallest standard install) and runs to $1,800 for a multi-phase erosion control package on a larger lot. Each family is sized to the disturbed-soil area and the runoff direction.
Single Silt Fence Run — 50 ft
A 50-foot run is the smallest standard silt fence install — typically the downhill edge of a single disturbed-soil area (a new driveway pour, a small addition footprint, a hot tub excavation). Woven geotextile filter fabric to WSDOT 9-14.5 spec, trenched 6 inches into the ground at the bottom edge so silt-laden runoff cannot undermine the fabric, attached to steel T-posts driven 6 feet apart for the structural load. Hardware-cloth backing on slopes over 10 percent for additional structural support.
Standard Silt Fence — 100 ft
A 100-foot run covers a typical residential lot perimeter on one side or two adjacent sides. Same WSDOT 9-14.5 spec, same trenching, same T-post spacing. Corners get a 90-degree return so silt cannot run around the end of the fence to the protected side. The standard installation reads correct to an SDCI or King County inspector on the first walk.
Combined Silt Fence + Straw Wattle
Straw wattles (compressed straw rolls wrapped in tubular jute or coir netting) handle concentrated runoff on slopes or at the toe of a steep cut. We combine silt fence (linear sediment control at the property edge) with straw wattles staked across the slope (concentrated-flow control) for sites with multiple runoff paths. Both go in to the same residential erosion-control standard.
Full Lot Perimeter — 200 ft and Up
A full-lot perimeter install runs silt fence along every disturbed-soil edge of a larger lot — typically a new build, a major addition, or a whole-property regrade. Same WSDOT 9-14.5 spec, same trenching, with corner returns at every direction change. Combined with inlet protection over storm drains within the property if the inspector requires it. Multi-day inspection-coordinated install where a city scheduler wants the fence walked before any work begins.
Add-Ons — Inlet Protection, Stabilized Construction Entrance, Removal
Inlet protection (fabric over storm drain grates near the work area) keeps sediment out of the city drain. Stabilized construction entrance (a section of crushed rock and geotextile at the truck access point) keeps mud from being tracked into the street where it would wash to the next storm drain. End-of-project silt fence removal — pull the fabric, pull the T-posts, dispose at the right stream, restore the trench line. All add-ons priced separately or bundled into the original install package.
How Erosion Control Silt Fence Install Works
Five sequential steps from the on-arrival site walk through the inspector pass and 30-day workmanship guarantee — the actual order we run on every Handis silt fence install so the fence passes the first walk instead of the third.
On-Arrival Site Walk & Runoff Mapping
We walk the lot with you (or the GC), identify the disturbed-soil edges, map the runoff direction (which way does water flow when it rains), confirm the linear footage needed and the corner locations, and verify any inlet protection or stabilized construction entrance the inspector flagged on the permit notes.
811 Locate Verification
We confirm the Washington 811 utility locate is on the property before any stake driving. T-posts driven 18 inches into the ground need clearance from buried gas, electric, water, and communications lines. If the locate is not current, we call 811 and reschedule the install for after the locate window — driving a T-post into a buried line is a serious incident we do not invite.
Trench, Stake, Fabric
We trench the bottom edge of the fence line 6 inches deep with a hand trencher or small skid-steer trencher where access allows. Steel T-posts get driven at 6-foot spacing, 18 inches into the ground. Woven geotextile filter fabric to WSDOT 9-14.5 spec gets attached to the T-posts (zip ties or steel staples), bottom edge buried in the trench, trench backfilled and compacted so runoff cannot undermine the fabric.
Corners, Add-Ons & Inspector-Ready Walk
Corners get 90-degree returns so silt cannot run around the end of the fence. Slopes over 10 percent get hardware-cloth backing for additional structural support. Inlet protection and stabilized construction entrance go in where the permit requires them. We walk the finished install with the homeowner or GC and confirm it reads correct to the inspector spec before leaving.
Inspection Coordination & 30-Day Workmanship Guarantee
If the install was scheduled against a permit inspection, we coordinate with the city scheduler so the inspector walks the fence within the inspection window. We document the work with photos for the 30-day workmanship guarantee. Weather damage from a major storm event, vandalism, and damage from a contractor's site work after the install are not workmanship issues and are outside the guarantee.
Erosion Control Silt Fence Pricing
Final pricing depends on linear footage, slope severity, the add-ons required (straw wattle, inlet protection, stabilized construction entrance), and whether end-of-project removal is included in the original scope. Request a free estimate for an accurate quote.
Send us the permit notes and a property photo — we will quote the fence before the inspector walks.
Why Handis for Erosion Control Silt Fence
Most silt fence calls we get are timed against an inspector walk — a stop-work order on an addition the GC has not started, a permit notes requirement for a driveway expansion that needs to break ground next week, a new-build site closing on the lot before October when the rain returns. The fence is not optional and it is not retroactive — the city inspector reads from WSDOT 9-14.5 and the install either passes or the project stops. Done right the first time, the fence holds through atmospheric river events and passes inspection without comment. Done wrong (no trench, T-posts too far apart, fabric clipped at the wrong height), it fails on the first walk and the project schedule slips.
WSDOT 9-14.5 spec — the spec the inspector reads from
Seattle SDCI and most King County jurisdictions enforce erosion and sediment control under the Stormwater Manual, with silt fence installed to WSDOT Standard Specification 9-14.5. The spec covers the fabric (woven geotextile filter fabric of a specific apparent opening size and flow rate), the trench (bottom edge of the fabric buried 6 inches into the ground so runoff cannot undermine), the support (steel T-posts driven 6 feet on center, 18 inches into the ground), and the attachment (fabric secured to the posts at a height that holds the load). We install to the spec literally — the inspector reads from it on the walk, and a fence built to it passes without comment.
Trench the bottom edge — not a stake-and-pin shortcut
The most common silt fence failure is a fabric-bottom-edge that was clipped to the ground with landscape pins instead of trenched. Runoff finds the gap under the pins, undermines the fence, and dumps silt straight downstream. Every Handis install trenches the bottom edge 6 inches into the ground with a hand trencher or small skid-steer trencher, backfilled and compacted. The fence holds through atmospheric river events instead of failing in the first storm.
T-posts at 6-foot spacing, not 10
Spec is 6-foot maximum T-post spacing. Spacing T-posts further apart saves a few stakes and gives the fabric room to balloon under runoff load — once the fabric balloons, the bottom edge lifts out of the trench and the install is failed. We drive T-posts at 6-foot spacing on flat lines and tighter (4 feet) at corners and slope transitions for the additional structural load.
811 locate before any T-post goes in
T-posts driven 18 inches into the ground need clearance from buried gas, electric, water, and communications lines. We confirm the Washington 811 utility locate is current on the property before any stake driving. If the locate is not current, we call 811 and reschedule the install for after the locate window — driving a T-post into a buried gas line is a serious incident we do not invite, and the cost of avoiding it is one phone call.
Inspection coordination — we do not leave you to chase the inspector
Where the silt fence is going in against a permit inspection deadline, we coordinate with the city scheduler so the inspector walks the fence within the inspection window. We send the install photos to the contact on the permit notes if the inspector is not available the same week. The fence holds in the meantime and the inspector signs off on the next available walk.
Honest scope — install, removal, contractor handoff on engineered work
We install and remove silt fence, straw wattles, inlet protection, and stabilized construction entrances. Engineered drainage (catch basins, infiltration trenches, French drains), permitted excavation, retaining-wall structural work, and any City of Seattle SDCI scope crossing into a permit-required correction route to a licensed Washington L&I contractor — we name the issue on the booking call and recommend a contractor when we know one.
30-day workmanship guarantee
If a silt fence we installed slumps, pulls a T-post we drove, blows out at a corner we built, or fails an inspector walk on something the inspector cites as our workmanship, we come back and fix it at no extra charge within 30 days. Weather damage from a 100-year storm event, vandalism, damage from a contractor's site work after the install (a backhoe drove through the fence; a delivery truck tore a section), and damage from animals or people on the site are not workmanship issues and are outside the guarantee.
Estimate
Tell us about the project — disturbed-soil area, runoff direction, permit notes from the city or county, the linear footage you think you need, any deadlines (inspector walk, project start date). We send a clear estimate that lists fence footage, add-ons, and the inspection-coordination plan.
Customer Reviews
Recent silt fence and erosion control reviews from verified Seattle-area customers.
City inspector flagged us on erosion control before the addition could break ground. Handis put up 80 feet of silt fence to WSDOT spec the next day — trenched, T-posts at 6 feet, geotextile woven fabric. The inspector signed off on the re-walk without a comment. Fence held through two atmospheric river events.
New build breaking ground in October. The GC's "we'll handle it" plan was a roll of landscape fabric stapled to wood stakes. Handis tore it out, installed a 200-foot full-lot perimeter to WSDOT 9-14.5 spec with hardware-cloth backing on the steeper edge. Passed the SDCI walk on the first try. Job stayed on schedule.
Driveway expansion in November. The runoff was heading straight for the curb storm drain. Handis put up 60 feet of silt fence plus a straw wattle across the cut slope, plus inlet protection on the storm drain at the curb. Inspector walked the next morning, no comment. Pour happened on time.
Hot tub excavation pulled up a 40 foot strip of yard. Handis installed a silt fence run along the downhill edge, trenched 6 inches, T-posts at 6 feet. They were upfront the install was overkill for the scope but the city walks every excavation over a threshold and the fence saves the inspection. Fence stayed up until the regrade was finished.
End of our addition project, time to pull the silt fence. Handis came back, pulled the fabric and the T-posts, restored the trench line with topsoil, hauled the materials to the right disposal stream. Lot looks like the fence was never there. Small project, but glad they handle the removal so we did not have to find another vendor.
Frequently Asked Questions
Common questions about Handis erosion control silt fence install — pricing, spec, permits, scheduling, inspection coordination, and what routes to a contractor.