Idaho IDT Erosion Control Products

Solmax DOT Standard Specification Product Chart (click image to expand)

Idaho IDT  - Erosion Control Methods

Idaho projects face steep mountain cuts, wind-scoured basalt plains, loessial hills that readily ravel, and alluvial valleys prone to spring runoff. Add long freeze–thaw seasons, rain-on-snow events, intense summer cloudbursts, and post-wildfire debris flows, and freshly disturbed soils can gully fast. ITD’s approach layers products to (1) protect bare soil, (2) slow and spread runoff, and (3) trap sediment until vegetation takes over.

Rolled erosion control products (RECPs). On new embankments, slope repairs, and roadside ditches, crews install straw, excelsior, coconut/coir, or blended blankets to shield soil and seed from rain splash, meltwater, and wind. Straw blankets suit short, gentle slopes and low-velocity swales; heavier coir or straw-coir mats handle longer grades and higher shear typical of mountain drainages. Blankets are trenched at the crest and toe, shingled downslope, and stapled to manufacturer patterns—with extra anchoring along windy Snake River Plain corridors.

Turf reinforcement mats (TRMs). Where velocities exceed temporary blanket limits—steep channels, outlet transitions, and curve bends—synthetic TRMs provide long-life reinforcement. Once roots knit through the mat, the vegetated system stands up to repeated snowmelt surges and summer storms, often reducing the quantity of rock armoring needed in constrained rights-of-way.

Hydraulic mulches and soil binders. Irregular cuts and rocky slopes are treated with hydraulic applications: hydroseed with hydromulch, bonded fiber matrix (BFM), or flexible growth media (FGM). BFMs form a breathable crust that resists sheet flow yet allows germination—useful for quick cover between storm windows. On windy or south-facing slopes, straw mulch is crimped into the soil and locked with tackifier or polymer binder to prevent blow-off until roots secure the surface.

Slope interrupters and perimeter controls. Fiber rolls (wattles) and compost filter socks placed on contour break long slope lengths, slow runoff, and trap sediment upslope before rills form. At the disturbance boundary, silt fence works well in fine-grained soils when trenched correctly; on stony ground or near traffic, heavier filter socks provide stability and easier maintenance.

Check structures and channels. Temporary rock or wattle check dams in construction ditches reduce velocities and drop out sediment. Spacing is set so each crest ponds water to the toe of the next—creating a stair-step energy dissipator. At culvert outlets and storm outfalls, crews pair blankets or TRMs with riprap over a filter layer; coir logs at the toe keep edges tight until vegetation takes hold. In very high shear zones, articulated concrete block mats add durability while allowing vegetation in the cells.

Inlet protection and track-out control. Curb socks, drop-inlet inserts, and gravel rings around grates keep sediment from entering storm systems during grading and paving. Stabilized construction exits—coarse stone over geotextile—limit mud tracked onto public roads, backed up by sweeping during wet seasons.

Basins, traps, and stockpiles. Sediment basins or traps intercept runoff from disturbed areas and provide settling volume ahead of discharge. Topsoil stockpiles are promptly seeded and mulched or covered; perimeter wattles or fence contain fines during storms.

Wildfire response. On burn-scarred slopes above highways, ITD often layers controls: BFM or FGM for immediate cover, wattles on contour to arrest rilling, and robust outlet armoring to handle ash-laden peaks during the first monsoons and snowmelt.

Seeding strategy and seasons. Dormant seeding in late fall is common at elevation; spring windows are used lower down. Native mixes are matched to elevation, aspect, and precipitation zone; coir-rich blankets and higher mulch rates help conserve scarce moisture on sunny slopes.

Inspection and maintenance. After storms or melt events, crews repair tears, reset stakes, remove sediment from devices (commonly at half-height), and reseed bare spots. Temporary controls come out once vegetation is established and slopes and channels are stable.

Bottom line: on ITD projects, erosion control isn’t one product—it’s a layered system that tames snowmelt and cloudbursts, protects waterways, and gives native vegetation the foothold it needs to lock Idaho’s soils in place.

Idaho IDT