ARCHIVED REPORTS_XR0012106 - Laserfiche WebLink

Home Browse Search

Unocal Station No #6981 January 26, 1996 when the VES was shut down in anticipation of the switch from thermal to catalytic mode, the VES had operated approximately 116 days, or 94% of the time All of the vapor extraction wells were open and used during system operation The VES was shut down in anticipation of a switch to catalytic oxidization mode. Historical VES chemical analytical data are summarized in Table 1, and historical VES operational data are summarized in Table 2 CURRENT QUARTER'S ACTIVITIES Field activities conducted at the subject site during the fourth quarter 1995 are discussed below. Monitoring and Sampling of Groundwater Monitoring_Wells Groundwater monitoring wells were monitored and sampled by MPDS Services, Inc. of Concord, California on October 25 and 26, 1995 Based on measurements collected by MPDS, the groundwater beneath the site appears to flow to the northeast at an approximate gradient of 0 005 (consistent with previous data) The groundwater table was approximately 0 87 feet lower than the previous quarter SAll groundwater monitoring wells (MW-1 through MW-13) at the site are sampled on a � semi-annual basis, during the first and third quarters. Only the perimeter wells MW-6 and MW-9 through MW-13 are sampled on a quarterly basis During the fourth quarter 1995, neither Total Petroleum Hydrocarbons as gasoline (TPHg) or benzene were detected in groundwater samples collected from the perimeter monitoring wells MW-6 and MW-9 through MW-13 The Quarterly Data Report dated November 22, 1995 was submitted by MPDS to the San Joaquin County Public Health Services (SJCPHS) and California Regional Water Quality Control Board (CRWQCB) VES Operation The vapor extraction system (VES) began operating in catalytic mode on May 16, 1995, under San Joaquin Valley Unified Air Pollution Control District (SJVUAPCD) Authority to Construct Permit Number N-3335-2-0, dated April 27, 1995, but could not meet the destruction efficiencies specified in the permit During May through November 1995, several attempts were made to meet the required 95% destruction efficiency by changing the VES operating parameters After each attempt to increase the destruction efficiency, the VES was shut down In addition to assessing the integrity of the mechanical operation of the abatement unit, the influent airstream was sampled for compounds that might have poisoned the catalyst, including lead (Pb), phosphorus (P), and chlorinated hydrocarbons • 485502-6 2