Laserfiche WebLink
1 ` <br /> Mr. Jeff Baker -2 - 5 December 2008 <br /> Stockton Terminals Technicalommittee <br /> were generally in A zone wells on the Time Oil property. The highest concentrations of <br /> TPHg and TPHd were in AR/MW-8A and AR/MW-23A at 100,000 micrograms per liter <br /> (Ng/L) and 1,100,000 pg/L, respectively. The highest concentration of TBA, was <br /> detected in the D zone at 1,600 pg/L in well TS/MW-2D. <br /> In the fall of 2004, the STTC began operation of two ozone sparge (OS) systems to <br /> clean up groundwater pollution migrating downgradient from the Site. The system is <br /> comprised of 57 A zone and 16 B zone wells connected to two 5 pounds-per-day <br /> (lbs/day) ozone generators. The OS system is divided into two portions. The west <br /> system is downgradient of Tesoro and the east system is downgradient of BP. System <br /> performance is evaluated using an array of six remedial observation wells, two midpoint <br /> wells, and four trigger wells. Between June and September 2008, the STTC estimates <br /> that the east system and west system had run times of 59 and 95 percent, respectively. <br /> The STTC attributes the excessive down-time in east system operation to construction <br /> related power interruptions. The STTC estimates that collectively, 396 pounds of ozone <br /> were injected and 132 pounds of hydrocarbons were destroyed during this period. In <br /> September, preventative maintenance was performed on both system compressors, <br /> and the Third QMR states that the ozone production equipment will be upgraded during <br /> the first quarter of 2009 with the objective of increasing system run times. <br /> The STTC monitors the ozone injection system using 12 A and B zone wells. A <br /> contingency plan is triggered if the concentrations of BTEX or MTBE in any of these <br /> wells exceed threshold concentrations for these compounds. Table 12 in the Third <br /> QMR shows that BTEX and MTBE concentrations in the ozone injection monitoring <br /> program wells were below threshold concentrations during the third quarter. The STTC <br /> installed wells pursuant to the 27 August 2008 Schedule of Well Installations, <br /> Destructions, and Relocations (Schedule). STTC located PS/MW-20, deemed it to be <br /> unserviceable, and abandoned it. Four new monitoring wells (PS/MW-20A through <br /> PS/MW-20D) were installed 40 feet north of former well PS/MW-20. Monitoring wells <br /> OW-3C and OW-3D were abandoned and replaced by OW-3CR and OW-3DR to avoid <br /> burial from operations at a nearby recycled building materials plant. <br /> The 15 September 2008 Addendum to Evaluation of Remedial Alternatives for D Zone <br /> Groundwater(Addendum) proposed to install TS/MW-3D near existing TS/MW-2D <br /> concurrently with the well installations described above. The purpose of TS/MW-3D is <br /> to conduct pilot testing of cleanup technologies for the D zone. The Third QMR does <br /> not mention whether proposed well TS/MW-3D was installed. However, the installation <br /> should be described in a well installation report as requested in our 18 September <br /> letter. That letter requested the installation report by 15 December 2008. <br /> During a 5 June 2008 meeting, Regional Water Board staff and STTC agreed that I and <br /> Mr. Gary Haeck of Stantec would work together to clarify and update the OS system <br /> contingency plan. On 15 September, Regional Water Board staff emailed a draft of <br /> suggested revisions to Stantec. For remedial observation wells, we requested that the <br /> revised plan: <br /> a) state the specific historical averages for each compound for each remedial <br /> observation well, <br />