A finite element computer model was developed to estimate the future settlement of the landfill and provide design criteria for the gangway connecting the pile supported ferry terminal to the landfill site.
The Oyster Point Landfill was operated as a sanitary landfill from 1956 to 1970. Upon completion of the disposal operations, various landfill closure activities took place through the late 1980s. The closed landfill then became the site for development of the Oyster Point Marina/Park.
TERRA was responsible for routine landfill water quality monitoring and storm water inspection and sampling programs and for preparing reports on the results of this monitoring on a semi-annual basis to the California Regional Water Quality Control Board and the San Mateo County Health Services Agency. TERRA was also responsible for monitoring of landfill gas at the perimeter of the landfill; completed an evaluation of methods to reduce landfill gas levels; and designed a gas interceptor and venting trench that successfully reduced gas levels in one area along the landfill perimeter that had experienced relatively high gas levels.
Because of our extensive knowledge of site conditions at the landfill, TERRA was retained by the ROMA Design Group to assist with environmental permitting and the evaluation of ongoing ground settlement at the Oyster Point Landfill for the design of the proposed Oyster Point Ferry Terminal. The environmental permitting activities on the project were focused on making it clear to regulators that the ferry terminal project was compatible with the existing landfill and that the work associated with upgrading the land-side of the new ferry terminal was functionally a maintenance activity.
The future settlement of the landfill was estimated by reviewing available site data and the geotechnical data on the nature and thickness of the underlying soft Bay Mud, developing a finite element computer model for estimating the past and future settlement of the landfill, calibrating/verifying the model by comparing the calculated past settlements to the measured settlements, and using the model to estimate the effects of future grading on settlement of the landfill. The settlement analyses were used to establish design requirements for a hinged gangway that leads from the landfill to the pile-supported ferry terminal.