Iowa DOT Erosion Control Products

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

Iowa DOT - Erosion Control Methods

Iowa work zones span glacial tills, deep loess in the west, and alluvial bottoms along rivers. Add long freeze–thaw seasons, spring snowmelt, intense convective storms, and prairie winds, and freshly disturbed slopes can ravel fast while ditches cut and deliver sediment to culverts and streams. Iowa DOT layers products that (1) protect bare soil, (2) slow and spread runoff, and (3) capture sediment until vegetation takes over.

Rolled erosion control products (RECPs). On new embankments, slope repairs, and swales, crews install straw, excelsior, coconut/coir, or blended blankets to shield soil and seed from rain splash 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 spring downpours. Blankets are keyed into anchor trenches at crest and toe, overlapped shingle-style, and stapled to manufacturer patterns—with extra anchoring on open, windy corridors.

Turf-reinforcement mats (TRMs). Where velocities exceed temporary blanket limits—steep roadside ditches, culvert outlets, and tight bends—synthetic TRMs provide permanent reinforcement. Once roots knit through the mat, the vegetated composite withstands repeated runoff and drawdown better than bare soil and can reduce the amount of riprap required in constrained rights-of-way.

Hydraulic mulches and soil binders. Irregular cuts, rocky patches, and broad 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. Where straw mulch is used, it’s crimped into the soil and locked with tackifier or polymer binder to prevent wind loss 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 before rills form. At the site boundary, silt fence excels in fine-grained tills when trenched and backfilled correctly; on stony shoulders or high-traffic zones, heavier filter socks offer stability and easier maintenance. Placement focuses on intercepting sheet flow high on the slope so water never gains erosive energy.

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 outfalls and culvert aprons, crews pair blankets or TRMs with riprap over an appropriate filter layer; coir logs at the toe keep edges tight until vegetation establishes. In very high shear zones, articulated concrete block mats add durability while still supporting plant growth in the cells.

Inlet protection and track-out control. Curb socks, drop-inlet inserts, and gravel rings around grates keep sediment out of storm systems during grading and paving. Stabilized construction exits—coarse stone over geotextile—limit mud tracked onto public roads; sweeping backs them up where sticky clays cling to tires.

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

Seasonal strategy, inspection, and maintenance. With long winters and shoulder-season storms, crews use dormant seeding, mulch plus tackifier, added anchoring on blankets, and quick temporary stabilization before shutdowns. After major rains or melt events, teams repair tears, reset stakes, empty inlet devices, remove accumulated sediment (often at half-height), and reseed bare spots. Temporary controls are removed once vegetation is established and slopes and channels prove stable.

Bottom line: on Iowa DOT projects, erosion control isn’t one product—it’s a layered system. Blankets, TRMs, hydraulic mulches, wattles, silt fence, check dams, inlet protection, basins, and stabilized exits work together to tame thunderstorms and snowmelt, protect waterways, and give vegetation the foothold it needs to lock Iowa’s soils in place.

Iowa DOT