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During the fourth quarter 2005, field parameters were collected on a monthly basis and select laboratory
<br /> parameters were collected on a quarterly basis During the fourth quarter 2005 monitoring event, all
<br /> samples were collected after purging three volumes of well casing The ozone infection monitoring plan is
<br /> listed below and a summary of frequency and significance of field and laboratory parameters is presented
<br /> in Table 3
<br /> Field Parameters (Monthly) pH, Dissolved Oxygen (DO), and Specific Conductivity
<br /> Laboratory Parameters (Quarterly) GRO, BTEX, five oxygenates, 1,2-DCA, EDB, ethanol, Chemical
<br /> Oxygen Demand (COD), Total Iron, and Heterotrophic Plate Count
<br /> Laboratory Parameters (Annually) Total Organic Carbon (TOC), Nitrates, Sulfates, Orthophosphates, and
<br /> Total Dissolved Solids (TDS)
<br /> Results
<br /> Field and analytical parameters collected under the ozone monitoring plan and the quarterly monitoring
<br /> program are presented in Tables 4 and 5 Change in DO concentrations for select observation and
<br /> background monitoring wells are presented in Figure 7 The historical GRO, benzene, and MTBE
<br /> concentration, and depth to water variation over time at select monitoring wells (MW-4 through MW-8) are
<br /> illustrated graphically in Figures 8 through 12
<br /> Petroleum hydrocarbon concentrations in all the monitoring wells appear to have decreased since the
<br /> operation of the ozone infection system During fourth quarter 2005, GRO concentrations at wells MW-5,
<br /> MW-6, MW-8, and MW-10 appear to have decreased since the previous monitoring event (September 8,
<br /> 2005) GRO concentrations in all the monitoring wells were below laboratory reporting limits during fourth
<br /> quarter 2005, however, elevated reporting limits in the range of 2,500 gg/L to 5,000 gg/L were used for
<br /> 01 wells MW-4, MW-6, and MW-8 Benzene concentrations were not reported above laboratory method
<br /> detection limits during the fourth quarter 2005 MTBE concentrations at wells MW-1, MW-3, MW-5,
<br /> MW-6, and MW-8 appear to have decreased, while the MTBE concentrations at wells MW-4, MW-9, and
<br /> MW-10 appear to have increased since the previous monitoring event The greatest decrease in MTBE
<br /> concentration was observed at well MW-6 (from 7,500 gg/L to 2,300 pg/L)while the greatest increase was
<br /> observed at well MW-4 (from 2,100 gg/L to 2,800 pg/L), since the previous monitoring event
<br /> During the fourth quarter 2005, the DO levels in observation wells (MW-3 through MW-10) varied in the
<br /> range of 0 9 mg/L to 9 4 mg/L, while the DO levels in background monitoring wells (MW-1 and MW-2)
<br /> were in the range of 1 1 mg/L 3 3 mg/L The DO levels in the observation wells continue to be generally
<br /> greater than the background monitoring wells, and is likely due to ozone infection DO levels in the
<br /> observation wells are consistent with levels measured during previous monitoring events
<br /> Concentrations of COD generally appear to correspond to changes in GRO concentrations for wells
<br /> MW-4, MW-6, and MW-8 (Figures 13 through 15) Inorganic constituents such as total iron, nitrates, and
<br /> sulfates appear to be influencing the heterotrophic plates counts in the groundwater (Figures 16 through
<br /> 18)
<br /> LIMITATIONS
<br /> This report was prepared in general accordance with accepted standards of care that existed at the time
<br /> this work was performed No other warranty, expressed or implied is made Conclusions and
<br /> recommendations are based on field observations and data obtained from this work and previous
<br /> investigations It should be recognized that definition and evaluation of geologic conditions is a difficult
<br /> and inexact art Judgments leading to conclusions and recommendations are generally made with an
<br /> incomplete knowledge of the subsurface conditions present More extensive studies may be performed to
<br /> 0.1reduce uncertainties This report is solely for the use and information of our client unless otherwise noted
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