Large-Scale Performance Evaluation of Sustainable Sediment Barrier Installations

Sediment barriers are used on construction projects to protect downstream waterbodies from sediment-laden stormwater runoff, most commonly being plastic-based silt fences. However, alternatives composed of natural materials, such as slash mulch berms and wattles, can be used. Despite this, little research has been completed on these practices in sediment barrier application to determine and improve performance through installation modifications. A modified ASTM D7351 sediment barrier testing methodology was used to evaluate slash mulch berm and wattle installations. Standard and modified installations were evaluated under Nebraska highway construction conditions for sediment capture, impoundment formation, and water quality treatment. Results indicated that uncompacted slash mulch berms were effective in overall sediment capture (98.1%) and significantly reduced turbidity (88.5%). A modified installation that reduced material usage through compact showed statistically significant improvements in water quality from the standard and increased sediment capture upstream of the berm from 61% to 73.5%. The standard straw wattle installation experienced undermining due to poor ground contact, resulting in low sediment capture (62.5%) and turbidity reduction (26.9%). Modifications (sod staples, increased overlap, and nondestructive staking) were made to improve ground contact, increasing sediment capture (85.4%) and turbidity reduction (39.4%). An excelsior wattle with enhanced installation techniques captured 75.3% of sediment. Overall, results indicate that slash mulch berms are highly effective in sediment barrier applications, especially when compacted, and wattle installations must ensure intimate ground contact. These findings can be used when considering natural materials and sediment barrier practices as alternatives to plastic-based products.