The project area of the tunnel alignment or Red Line Corridor is located in the City of Los Angeles on the north and south slopes of the Santa Monica Mountains. The alignment corridor originates at the southern boundary of Runyon Canyon Park and portions of Nichols Canyon, and extends to residential areas north of Solar Drive and Mulholland Drive north to Universal City.
Dean Ryan been tasked to assist the MTA with field investigations of the study area. The scope of services for the botanist and arborist consists of periodic on call, as needed monitoring and field investigations of the status of native/natural and landscaped/horticultural botanical resources found within the tunnel alignment for the Red Line Corridor from the southern boundary of Runyon Canyon Park north to Solar Drive and Universal City. This geographic area contains both native/natural and landscaped/horticultural vegetation. The area of concern includes a corridor 1,000 feet wide on either side of the center-line of the tunnel alignment. The objective of this effort is to collect sufficient data to determine if substantial changes occur to native vegetation or plant communities and/or residential landscaped areas due to dewatering of areas in the mountains during and after tunnel construction, and to document when these effects may occur.
An overview of the entire study area will be conducted by both the botanist and arborist to evaluate preexisting conditions of native/natural and landscaped/horticultural vegetation in the project area. Damage to botanical resources caused by previous abiotic and biotic factors will be considered distinct and separate to potential impacts caused by tunnel construction dewatering. Preexisting abiotic factors which may detrimentally affect vegetation include prolonged drought cycles, fires, frost or freeze cycles, irrigation regimes or lack thereof, vegetation maintenance practices including the amount of soil covering the trunk/root flare region of trees and shrubs, and rototilling or other construction and landscaping activities of ground surfaces in and near the root systems of trees and shrubs. Preexisting biotic factors, which affect vegetation, include plant diseases, caused by pathogens or pests, and competition from other species.
The botanist will review with ecological issues concerning landscaped vegetation comprised primarily of horticultural, ornamental species which may be either native or introduced species found on residential properties such as yards, property borders and hillsides. The botanist, in cooperation with the arborist, will be required to conduct plant ecological methodologies designed to evaluate the potential use of water by trees and shrubs in the corridor. Both the botanist and arborist will recommend appropriate surveys in the corridor to determine damage caused by dewatering to native/natural and landscaped/horticultural botanical resources, respectively.
Botanical Resources Survey Reports will be submitted by the botanist and arborist to MTA and they will present the results of the periodic, on call/as needed Botanical Resource Field Surveys. These reports will include, but not limited to: an overview of the study area showing damaged botanical resources (if any) affected by dewatering; a discussion of the general vegetation types found in the study area and their condition; general identification of significant resources in the study area, such as oak or sycamore tree habitats or groves, that show verifiable dewatering damage.