SITE INFORMATION AND CORRESPONDENCE

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Mr. Joe Aldridge - 2 - 4 December 2008 NuStar Terminals Stockton Facility at 90,000 micrograms per liter (Ng/L) and 220,000 flg/L, BTEX at 14,000 Ng/L, 8,000 ug/L, 3,300 pg/L, and 18,000 pg/L, respectively, and MTBE at 210,000 pg/L. The maximum TBA concentration was detected in PS/MW-15 at 2,800 pg/L near the downgradient edge of the plume. PS/WC-4S was sampled in lieu of monitoring well UP/MW-1 which has been buried by construction activities. NuStar conducted the C and D zone vertical groundwater investigation pursuant to the 21 July 2008 Revised Vertical Groundwater Characterization Work Plan (Revised Work Plan) and our 19 August 2008 comment letter. Our letter requested that NuStar implement the investigation by 30 September. However, the start of the investigation was delayed until mid- October due to miscommunication with the drilling company. Drilling and sampling took about one month during which NuStar regularly updated Regional Water Board staff on the progress of the investigation and received regulatory oversight by email and telephone. During the investigation, NuStar advanced 21 borings (NS-1 through NS-21) and collected soil and groundwater samples from the A through D groundwater zones. Ten borings were advanced to the C zone and one boring was advanced to the D zone. The preliminary results of the vertical investigation show that groundwater samples collected from several borings contained TPHd, TPHg, BTEX, MTBE and TBA that exceeded water quality objectives (WQOs). These results show that vertical delineation at this site has not been achieved. NuStar has stated that it believes some of the D zone contamination originated from other bulk storage facilities. During a 24 November teleconference, NuStar said it will not advance additional D zone borings at this time and will submit the results of the investigation containing recommendations for monitoring well installations by 30 January 2009. Our comments are presented below. 1. As Regional Water Board staff stated during the 24 November teleconference, the preliminary results show that the investigation is incomplete because petroleum hydrocarbons in the D zone are not vertically or laterally delineated. In addition, the installation of D zone monitoring wells will be necessary to monitor plume migration and concentrations in the D zone. NuStar's proposed 30 January 2009 report on the investigation must contain recommendations to (1) install C and D zone wells to obtain deeper-zone gradient and flow direction data for groundwater underlying and downgradient of the NuStar facility, (2) complete delineation of COCs to non-detect, and (3) install wells at the vertical and lateral ND extents of the plume to assess the efficacy of active remedial technologies, once implemented. 2. The 31 October 2008 Third Quarter 2008 Quarterly Site Status, Groundwater Monitoring and Remedial Summary Report (STTC Third QMR) submitted by Stantec Consulting Corporation (Stantec) on behalf of the Stockton Terminals Technical Committee (STTC) reported that during October 2008, a site-wide resurvey of STTC and NuStar groundwater monitoring wells was conducted as recommended by Geotracker. As seen in the groundwater elevation maps included in the STTC Third QMR, the site-wide resurvey of the well casing elevations has eliminated the apparent groundwater mounds and sinks historically present in the vicinity of PS/WC-1M, PS/NM-20, and OW-413. This result