Long Beach, CA
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File #: 16-0216    Version: 1 Name: LBGO - Elevation Changes May - Oct 2015
Type: Agenda Item Status: Approved
File created: 2/23/2016 In control: City Council
On agenda: 3/8/2016 Final action: 3/8/2016
Title: Recommendation to receive and file the report, “Elevation Changes in the City of Long Beach, May 2015 through October 2015.” (Citywide)
Sponsors: Long Beach Gas and Oil
Indexes: Report
Attachments: 1. 030816-C-8sr&att.pdf
TITLE
Recommendation to receive and file the report, “Elevation Changes in the City of Long Beach, May 2015 through October 2015.” (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 May 2015 through October 2015. 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 six-month survey show that elevations were stable in the Civic Center, Central City, Alamitos Bay, and Naples. The offshore area was stable except for a small area adjacent to Island Grissom, which experienced an increase of 0.09 foot (1.1 inch). The increase may have been due to increased injection in the area. In the Harbor District, Piers A and S experienced a decline of up to 0.07 foot (0.8 inch) during the six-month period. The decline is at the high end of normal limits and not expected to continue with continued mitigation measures.

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 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 February 16, 2016 and by Budget Management Officer Victoria Bell ...

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