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March 1, 1996 <br />Page 2 <br />- Cause of Release <br />Tank 13 is a wastewater/slop product storage tank that is filled by a pump in the under- <br />ground slop tank fed by the API separator. Currently the only flow through the API <br />separator is groundwater and trace product extracted by the remedial system. Normally <br />an automatic forwarding pump passes the effluent from the API separator through a <br />carbon system prior to discharge to the San Joaquin River. Sometime between 2/6 @ <br />6PM and 2/7 @ 7AM, this forwarding pumped failed due to a stuck float switch and the <br />extracted groundwater began to fill Tank 13 via the API separator and underground slop <br />tank. Tank 13 was not equipped with a high level shutdown sensor; therefore, when the <br />tank filled, the extraction pumps continued to operate and overfill the tank until the system <br />was shut down by Shell personnel on 2/7. <br />Emergency Response Actions Performed <br />On 2/7/96, the following emergency response actions were taken: <br />• Release was reported to the Office of Emergency Services. <br />The release area was diked off and a vacuum truck (Ramos Environmental) <br />was brought in to pump up the ponded water. Approximately 3,800 gallons of <br />wastewater were recovered and disposed of off-site. <br />On 2/9/96, soil below the release area was excavated by Ramos Environmental until <br />saturated conditions were no longer encountered (approximately 3 to 6 inches below <br />grade). This soil was stored on and covered by visqueen sheets. Approximately 25 cubic <br />yards of soil were excavated. <br />Source Removal Actions <br />On February 14 and 15, 1996, spot excavation of several areas within the release area was <br />performed (NG Chemical) under the direction of Michael P. Kith from the San Joaquin <br />County Health Department. Less than 5 cubic yards of soil were excavated. Soil samples <br />have been obtained and sent to a State certified laboratory for analysis. The soil will be <br />disposed of off-site once the results have been obtained. <br />Corrective Actions Taken <br />A high level sensor has been installed in Tank 13 and tied into the remedial system control <br />panel. If a similar pump failure occurs and wastewater begins to fill Tank 13, the <br />groundwater extraction pumps will be shut down once the tank is filled to capacity. <br />Recommendations <br />The area in question has been impacted from past releases and is currently under <br />remediation. In addition to the groundwater extraction system currently operating, a soil <br />3151353A1SPU_L.D0C <br />