TITLE
Recommendation to receive and file the report, “Elevation Changes in the City of Long Beach, November 2010 through May 2011.” (Citywide)
DISCUSSION
The City of Long Beach, through the Long Beach Gas and Oil Department (LBGO), supervises oil production and subsidence control operations in the Wilmington Oil Field. LBGO conducts elevation surveys every six months to monitor elevation changes in the oil fields and adjacent city areas. This report focuses on elevation changes that have occurred from November 2010 through May 2011. The LBGO survey includes the following areas: Civic Center, Central City, Alamitos Bay, Naples, Harbor District, and an offshore area encompassing the four offshore oil islands.
The results of the six-month survey show that elevations were stable in the Central City, Alamitos Bay, Naples, and the offshore areas. A portion of the Civic Center area experienced an elevation gain of up to 0.10 foot (1.2 inches). Elevations in the western portion of the Harbor District increase up to 0.12 foot (1.4 inches). The elevation increases appear to be the result of regional geologic factors and are not of concern.
The LBGO survey uses a series of benchmarks to determine elevation changes. Studies by the Department’s engineers and geologists show that the benchmarks may rise and fall in such a manner as to make a survey either optimistic (slightly up in elevation) or pessimistic (slightly down in elevation). These changes in elevations may be associated with tidal cycles, temperature changes, and/or deep earth tectonic changes or re-pressuring operations. Surface elevations in a rebounded area can be expected to fluctuate under changing water flood conditions.
This matter was reviewed by Deputy City Attorney Richard Anthony on August 22, 2011 and Budget Management Officer Victoria Bell on August 19, 2011.
TIMING CONSIDERATIONS
City Council action on this matter is not time critical.
FISCAL IMPACT
There is no fiscal impact or loc...
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