California DOT hydroseeding & erosion-control specs.
Caltrans Section 21 defines the material requirements for hydraulically-applied erosion control — fiber, tackifier, BFM composition, and application method — while seed species and rates for a given job come from the project plans. Match your slurry to these material rules, then confirm products against the Authorized Materials List (AML).
Other state specs
Section 21 — Erosion Control (2024 Standard Specifications)
Material-spec state
Bonded Fiber Matrix (BFM)
21-2.02J: 100% wood fiber (≥50% retained on the No. 25 sieve) plus tackifier bonded to the fiber at ≥10% of dry combined weight.
Fiber requirements
21-2.02D: ≥25% by volume 3/8-inch strands; ≥40% retained on the No. 25 sieve; water-holding capacity ≥1,200% (ASTM D7367); moisture ≤15% (California Test 226); boron under 250 ppm.
Tackifier
21-2.02E: plant-based polysaccharide (guar, psyllium, or starch) OR a prepackaged anionic polymeric emulsion (acrylic/acrylamide copolymers) with residual monomer ≤0.05% by weight; must remain functional ≥180 days.
Hydromulch application
21-2.03D: minimum 1,000-gallon continuous-agitation tank; begin applying within 60 minutes of adding seed; complete an area’s material within 72 hours.
Approved / Qualified Products
Authorized Materials List (AML) for erosion control (METS/Roadside).
Portal: https://mets.dot.ca.gov/aml/ — verify manually; some DOT portals block automated access.
Summarized from the Caltrans standard specifications for reference only — verify against the current official spec and your project’s plans / special provisions before bidding or applying. Source: official specification.
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