SITE INFORMATION AND CORRESPONDENCE

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Bert E. Van Voris - 13 - 17 September 2004 Supervising Engineer While not immediately germane to this topic,the RWD should provide a table summarizing the historical use of soil amendments (i.e., listing for each LTU field the date(s) of application, type of soil amendment, and loading). Characterization and Evaluation of Site Soils The RWD characterizes site soils using published information on area soils and soil sampling data collected by HDR in 2001, results reported by Dellavalle in 2002 and 2004, and additional soil sampling by Kennedy/Jenks performed in 2003. The RWD references reports submitted by HDR in 2000 and 2001 that contain soil data and evaluate the effects of Musco's discharge on soil. It identifies pH, SAR (sodium adsorption ratio), ESP (exchangeable sodium percentage), and EC (electrical conductivity at 25 degrees Centigrade) as soil parameters used to designate a soil as normal, saline, saline/sodic, and sodic. It describes the attributes of saline and sodic soils and the challenges these soils present for crop growth. It briefly characterizes soil quality data obtained by HDS in 2001 and by Dellavalle Laboratories and Kennedy/Jenks in 2002 and 2003 and presents 2002 and 2003 soil analytical data in Table 7. The Monitoring and Reporting Program (MRP)included in the WDRs require Musco to monitor soil in at least 10 locations within the LTU and at least one background location"(i.e., in an area that historically has not received process wastewater)." The same background soil location was employed in annual soil sampling performed pursuant to the MRP in 2002 and 2003. The RWD indicates site soils contain very low nitrate,with the exception of soils in the background location and Park West, a 7.5-acre field west of the facility. Musco historically discharged olive leaves to Park West, as well as dredgings from the pond. The RWD's Figure 9 depicts the 2002 and 2003 background soil sampling location as immediately north of Park West, whereas this location is clearly depicted in figures contained in Dellavalle's reports as being within Park West. Background soil samples collected in 2002 and 2003 contained elevated concentrations of nitrate. While the RWD attributes the elevated nitrate in background soil as"due to previous agricultural practices prior to Musco ownership,"13 it indicates the increased concentration of nitrate with depth is difficult to explain: These [background] samples show nitrate concentrations that ranged from approximately 20 to nearly 150 mg/kg between the surface and 72 inches below ground surface. However, in both profiles sampled, the nitrate(as nitrogen)concentration increased with depth. This trend is somewhat different to that observed in any agricultural soils,where nitrate as well as other nitrogen species are generally higher in concentration near the surface and are found in much lower concentrations in the subsurface.14 The RWD's Table 9 presents 2002 and 2003 soil monitoring data from Park West, South Ridge (prior and 45 days following leaf application), and South Ridge in areas that had not received leaf application. It also includes 2002 and 2003 data from comparable depths from the background soil sampling location, but not data for the leaf application area north of the eastern portion of South Ridge. Park West soil collected in 2003 contained nitrate-nitrogen (expressed as mg/kg) ranging from 636 (0-6"bgs)to 95 (52- 60" bgs). Background soil collected in 2002 contained nitrate-nitrogen ranging from 33 (0-6" bgs)to 143 (60-72" bgs). The RWD dismisses the significance of the elevated nitrate concentrations in Park West soils "since past practices may be influencing what is observed and measured in soils currently."15