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•�` Mr. James L.L.Barton
<br /> July 5, 2005
<br /> Page 3 of 5
<br /> 2005, approximately 44,047 gallons of extracted water were treated. Approximately 3.5 pounds of TPHg,
<br /> 1.7 pounds of BTEX, and 0.9 pounds of MTBE were removed from the groundwater during that period.
<br /> However, the load on carbon unit Cl during that period was zero, since there was no documented
<br /> breakthrough in lead unit C2 based upon the February 24,2005 sample.
<br /> March 30, 2005: System was down upon arrival to the site due to scaling in carbon unit C2. No treatment
<br /> system samples could be collected. Between March 18 and March 30, 2005, approximately 39,357 gallons
<br /> of extracted water were treated. Approximately 3.1 pounds of TPHg, 1.6 pounds of BTEX, and 0.8 pounds
<br /> of MTBE were removed from the groundwater during that period. However, the load on carbon unit CI
<br /> during that period, based upon 82% air stripper efficiency suggested by the recent analytical results, was
<br /> only 1.0 pound.
<br /> May 6,2005: Conducted acid wash on unit C2.
<br /> May 10,2005. Conducted acid wash on unit C1 and restarted the treatment system.
<br /> May 23, 2005: Sampled treatment system; breakthrough detected in lead unit C2 (2.1 ppb MTBE) and trail
<br /> unit C1 (52 ppb). Preliminary results were provided to Ground Zero late on May 31, 2005.
<br /> May 31, 2005: After preliminary results from May 23, 2005 sampling indicated carbon breakthrough,
<br /> Ground Zero immediately resampled C1 and C2 to confirm breakthrough and shut down the treatment
<br /> system. Ground Zero notified Jim Barton of the Regional Board via voicemail on the morning of June 1,
<br /> 2005 and followed up with an email to Mr. Barton and Mr. Jeff Wong of San Joaquin County EHD on the
<br /> morning of June 2, 2005. Confirmation samples indicated C2 contained 2.4 ppb MTBE and C 1 contained 29
<br /> ppb MTBE. Between May 10 and May 31, 2005, approximately 43,079 gallons of extracted water were
<br /> treated. Based upon the May 23, 2005 analytical results, approximately 1.5 pounds of TPHg, 0.8 pounds of
<br /> BTEX, and 1.6 pounds of MTBE were removed from the groundwater during that period. However, the
<br /> load on carbon unit C 1 during that period, based upon 82%air stripper efficiency, was only 0.7 pounds.
<br /> ANALYSIS OF BREAKTHROUGH
<br /> Table 1 summarizes operation of the treatment system including carbon usage since virgin carbon was first
<br /> placed in the carbon units in early December 2003. From December 4, 2003 until the air stripper was
<br /> brought on-fine in August 2004, approximately 95.1 pounds of VOCs (TPHg, BTEX, MTBE combined)
<br /> were removed via GAC with no breakthrough, based upon analytical results of treatment system samples.
<br /> Breakthrough occurred in C1 on October 26, 2004 after approximately 95.7 pounds of VOCs were removed.
<br /> Since the spent carbon was replaced in Cl, approximately 47.2 pounds of VOCs were removed, with an
<br /> estimated load of approximately 5.2 pounds on C2 and 3.0 pounds on Cl. Based upon these estimates, the
<br /> breakthrough of carbon in both vessels was not expected.
<br /> The unexpected breakthrough of the carbon units may be attributed to one or more of the following factors:
<br /> 1. Conducting the acid wash on the carbon units to remove scale that built up in the pipe fittings and
<br /> screened manifolds of the carbon units. The acid wash was recommended by our contractor, Deltech
<br /> Geotechnical Support and approved by the GAC supplier, Carbon Resources, LLC. Carbon Resources
<br /> indicated that its carbon is acid-washed and as such, applying acid to the carbon would not affect the
<br /> adsorption capacity of the GAC. Information related to Carbon Resources' product is included as
<br /> Attachment A. It should be noted that the pH of the water exiting the carbon units after the acid bath
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