County of Los Angeles Flood Control District
CEQA/NEPA Documentation (IS/MND and EA/FONSI)
Air Quality and Greenhouse Gas Emissions Analyses
Cultural Resources Phase I Assessment
Biological Resources Surveys
CEQA/NEPA Environmental Documentation for Sediment Removal
BonTerra Psomas is preparing environmental documentation pursuant to CEQA (Initial Study/Mitigated Negative Declaration—IS/MND) and NEPA (Environmental Assessment/Finding of No Significant Impact—EA/FONSI) for the proposed removal of up to 4.4 million cubic yards of sediment from Big Tujunga Reservoir (BTR) into Maple Canyon Sediment Placement Site (SPS). Sediment removal would occur annually during the non-storm season for approximately five years, depending on the amount of rainfall and sediment deposition in coming years.
The project would minimize air quality impacts through implementation of one of two alternative transport methods: either via Low Emissions Trucking or via Conveyor Belt. Once the reservoir is fully dewatered and the access roads paved and prepared for truck traffic or conveyor belt transport, sediment will be excavated from BTR and transported to Maple Canyon SPS, likely utilizing its remaining capacity, resulting in closure.
This is an ongoing, multi-disciplinary project, requiring regular coordination with the County of Los Angeles and U.S. Forest Service. To support the IS/MND and EA/FONSI, analyses were completed and/or reports were produced for air quality (using the California Emissions Estimator Model—CalEEMod), biological resources, jurisdictional resources, cultural resources, greenhouse gas emissions, and noise. In addition, BonTerra Psomas completed focused surveys for arroyo toad, Sierra Madre yellow-legged frog, special status fish species, western pond turtle, special status plants, least Bell’s vireo, and southwestern willow flycatcher.