TITLE
Recommendation to receive and file the report, "Elevation Changes in the City of Long Beach, May 2004 to November 2004." (Citywide)
DISCUSSION
The City of Long Beach, through the Department of Oil Properties (DOP), supervises Wilmington Oil Field oil production and water injection, and monitors subsidence control operations. Elevation surveys have been conducted at least semi-annually since 1965. Eleven permanent stations of the Long Beach Global Positioning System (GPS) Deformation Network were completed in Spring 2003. Two new stations were added since the May 2004 Elevation Survey. Now, thirteen permanent GPS stations are being fully utilized in combination with mobile GPS survey equipment to conduct the DOP semi-annual elevation surveys. This report discusses bench mark elevations surveyed in November 2004 and compares elevation changes that have occurred since completion of the May 2004 and November 2003 surveys. These data are also compared with earlier semi-annual data for analysis of trends. The surveyed area includes the Harbor District, Civic Center, Central City, Alamitos Bay, and Naples. City elevations were stable or increased slightly in elevation for both the six-month and one-year periods. Both survey periods are interpreted to be "up" and most likely related to movement of the entire Long Beach area due to "earth forces" and not the oil-operations. A six-month localized elevation increase of 0.050 feet (0.600 inches) along Ocean Boulevard between Cherry and Alamitos is being carefully monitored. Within the Harbor District, elevations also remained stable or increased slightly during both survey periods. A slight elevation increase of up to 0.062 feet (0.744 inches) occurred at Pier G during the six-month period. The curtailed Tar II steam flood area around Henry Ford Avenue lost up to -0.056 feet (-0.672 inches) of elevation. Alamitos Bay, Naples, and the oil islands Chaffee and Freeman remained stable for the six-month period. Elevat...
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