COMPLIANCE INFO_PR0440063_1990-2019

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Musco Family Olive Comp - 2 - 14 August 2006 r On 31 May 2006, Musco Family Olive Company (Masco) submitted a response to the NOV indicating the current well network is adequate and meets the requirements of Title 27 and WDRs No. R5-2005-0024. Musco contends that perched groundwater beneath the surface impoundments is spatially discontinuous and is present primarily at the north-east and south- east end of the surface impoundments. On 5 June 2006, Board staff met with Musco, and consultants Kennedy-Jenks and Kleinfelder Inc., to discuss the NOV. Staff recommended that Musco propose an alternative response that complies with Title 27 by the 15 June 2006 deadline in the NOV. Musco submitted a Proposed Alternative Detection Monitoring Program (DMP) dated 14 June 2006, outlining the current DMP and elements of the program monitoring the surface impoundments that include: the Title 27 lined ponds and Leachate Collection and Return System (LCRS), lysimeters, and groundwater monitoring well network. Musco reiterated staff's concerns about declining water levels in well W-2 and MW-11 and indicated the main concern is that the existing monitoring well system may not be adequate to monitor the operation of the surface impoundments. The report discussed Musco's understanding of the hydrogeology of the site. According to the report, groundwater beneath the site exists in at least two separate zones, shallow perched and a deeper zone. The shallow perched zone is interpreted as spatially discontinuous across the site and completely absent from borings west-northwest of MW-11. The evaluation concludes that the shallow perched zone may not be an adequate detection monitoring point. In response to staffs request for an alternative DMP that complies with Title 27, Musco concluded that additional subsurface investigations or monitoring wells were not required. Alternatively, Musco proposes more frequent monitoring of the LCRS and lysimeters in conjunction with a "high accuracy" surface impoundment water level study as a substitute for improvements to the DMP. Leachate released from the Title 27 ponds would collect in the LCRS and the pond sumps; however, the lysimeters installed to monitor the vadose zone do not collect sufficient water to evaluate whether the surface impoundments leak. The current well network does not monitor groundwater for potential impacts from the surface impoundments. Staff agrees that the perched zone is dry and therefore is an inadequate detection monitoring location. Because of this condition, the current shallow well system does not meet the requirements of Title 27 Sections 20415 and 20420. In addition, Staff has identified three potential water bearing zones (based on drilling logs) beneath the surface impoundments that require exploration and additional monitoring to meet the requirements of Title 27. These are: the shallow zone between an approximate depth of 50 and 70 feet bgs; the intermediate zone or gravel zone between an approximate depth of 80 and 82 feet bgs; and the deep zone at an approximate depth between 90 and 100 feet bgs. In staff's professional judgment, additional wells are needed to monitor potential water quality impacts of these zones per Title 27, Section 20415 and 20420 and WDRs No. R5-2005-0024. The enclosed Memo provides staff's full evaluation of groundwater conditions.