TITLE
Recommendation to receive and file the report, “Elevation Changes in the City of Long Beach, November 2015 through October 2016.” (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 2015 through October 2016. The LBGO survey includes the following areas: Civic Center, Central City, Alamitos Bay, Naples, Harbor District, and the offshore area encompassing the four oil islands.
The results of the last two six-month surveys indicate that elevations were stable in the Civic Center, Central City, Alamitos Bay, Naples, and the offshore area. The Harbor District was stable for the year with the exception of Pier D. Pier D experienced an elevation increase of up to 0.07 foot (0.8 inch) during the first six-month period of the year. The increase may have been due to increased injection in the area and did not continue during the second half of the year.
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, drought, temperature changes, deep earth tectonic changes and/or re-pressuring operations in the oil field. Surface elevations over the active Wilmington Oil Field can be expected to fluctuate under changing water flood conditions.
This matter was reviewed by Deputy City Attorney Richard F. Anthony on January 12, 2017 and by Budget Analysis Officer Julissa José-Murray on January 17, 2017.
TIMING CONSIDERATIONS
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