TITLE
Recommendation to receive and file the report, “Elevation Changes in the City of Long Beach, May 2010 through October 2010.” (Citywide)
DISCUSSION
The City of Long Beach (City), 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 May 2010 through October 2010. 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 Civic Center, Central City, Alamitos Bay, Naples, and the Harbor District. A portion of the offshore area surrounding Island Grissom experienced an elevation gain of up to 0.096 feet (1.2 inches). LBGO is mitigating the elevation change in this area by decreasing water injection requirements.
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 item was reviewed by Deputy City Attorney Richard F. Anthony and by Budget Management Officer Victoria Bell on February 14, 2011.
TIMING CONSIDERATIONS
City Council action on this matter is not time critical.
FISCAL IMPACT
There is no fiscal impact or local job impact associated with this action.
SUGGESTED ACTION
Approve...
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