HELIX Environmental Planning (HELIX) prepared biological studies, regulatory permitting, and environmental documentation for the expansion of the Sycamore Landfill in San Diego County. HELIX also conducted maintenance and biological monitoring of open space areas for prior mitigation areas, as well as planning for mitigation that will result from the proposed expansion. The 86 million-cubic-yard landfill expansion includes a horizontal and vertical expansion of the Sycamore Landfill, increases in incoming daily tonnage, and relocation of an electrical transmission line by SDG&E to accommodate the expansion. HELIX monitored and maintained previously translocated populations of sensitive species, salvaged and translocated sensitive plants species prior to construction, implemented a site-wide weed management plan, and provided environmental compliance services for construction.