Seattle City Light (SCL) constructed, owns, and operates three hydropower dams along the Skagit River, in Northern Cascades National Park (NCNP). Three reservoirs created by the dams are surrounded by Ross Lake National Recreation Area (RLNRA); NCNP surrounds the Recreation Area, and includes designated wilderness area, old-growth timber, and habitat for Northern Spotted Owl and other species of concerns. In support of the Skagit Hydropower Relicensing Project, relicensing application to FERC, SCL and HDR performed an extensive acoustical study. The study included 7-day unattended noise measurements at six locations in the study area, during peak summer recreation season, and springtime off-peak season. Those measurements included continuous acoustical and meteorological measurements, and continuous digital audio recordings. Measurement results and digital audio recordings were processed using National Park Service soundscape study methods, and included the determination of the percent of time anthropogenic noises were audible and also the calculation of the natural ambient sound level (Lnat). The final study report identified: CFI8X input data, powerhouse dimensions and spectral sound power levels for building exteriors, for transformers, switchyards, and corona noise; the average minimum heights of the transmission lines by segment; the mobile terrestrial noise source inventory; maximum pass by SPL for vehicles by pavement type and speed, ADT from 2017 – 2022; sound power levels and flow rates for dam spills; maximum spectral sound power levels for sirens and telephones; noise emissions from a bell on a locomotive occasionally rung by tourists; emergency generator noise emissions; the inventory of SCL-owned boats; the variable noise source inventory results; spectral sound power level for lawnmowing equipment; ambient noise measurement results summary; audio review summary, and; model validation results. Cadna-A noise modeling results were expressed using noise contours overlaid upon a terrain map of the study area.
PRIMARY CANDIDATE NAME: Tim Casey
ORGANIZATION: HDR Engineering, Inc.
PROJECT ROLE: Sound Study Lead
TELEPHONE NUMBER: 612.859.9839
EMAIL ADDRESS: tim.casey@hdrinc.com
SECOND CANDIDATE NAME: Benjamin Copenhaver
ORGANIZATION: HDR Engineering, Inc.
PROJECT ROLE: Sound study lead acoustical analyst
TELEPHONE NUMBER: 763.591.5494
EMAIL ADDRESS: benjamin.copenhaver@hdrinc.com
THIRD CANDIDATE NAME: Michael Aronowitz
ORGANIZATION: Seattle City Light
PROJECT ROLE: Environmental Studies Lead
TELEPHONE NUMBER: 206.858.3061
EMAIL ADDRESS: michael.aronowitz@seattle.gov
