DATE: September 13, 2022
SUBJECT:
Title
ORDINANCE AMENDING THE FY 2023 BUDGET INCREASING THE EQUIPMENT OUTLAY AND OTHER CAPITAL PROJECTS BY $250,000 TO PREPARE ENGINEERING ANALYSES FOR A POTENTIAL ABANDONMENT BY SLURRY FILLING OF THE FORMER SILVER GATE POWER PLANT COOLING WATER TUNNELS, TO BE FUNDED FROM A RECENT SETTLEMENT PAYMENT PERTAINING TO THE TUNNELS FROM SAN DIEGO GAS AND ELECTRIC COMPANY.
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EXECUTIVE SUMMARY:
District staff recommend amending the FY 2023 budget to increase the equipment outlay and other capital projects by $250,000 to prepare engineering analyses for the potential abandonment by slurry filling of underground tunnels located at 2205 East Belt Street in the City of San Diego. The tunnels were installed in the early 1940s by a San Diego Gas and Electric Company ("SDG&E") predecessor to provide cooling water intake and discharge for the former Silver Gate Power Plant and have been out of operation since the early 1980s. The former intake and discharge tunnels are approximately 700 feet long, each consisting of a pair of 8-foot by 8-foot square reinforced concrete chambers. The intake and discharge tunnels are approximately 20 feet wide and joined segments are approximately 38 feet wide (Attachment A). Approximately 490 feet of the intake tunnel and 450 feet of the discharge tunnel are within Port District jurisdiction. Approximately 250 feet of each tunnel extends to the north beyond the Port District's jurisdiction. These cooling tunnel sections were previously abandoned in place with concrete slurry by SDG&E.
If the Board approves this action District staff will conduct engineering analyses for the tunnels to be abandoned in place and filled with concrete slurry. This would include analysis of partial removal of the top six (6) feet of the two (2) concrete tunnel access structures, then pumping concrete slurry to fill the void in the tunnels (Attachment A). The analysis would also include excavation of the surrounding soi...
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