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Charanjit S. & Davinder K. Jutla July 29, 2014
<br /> 3940 N. Tracy Boulevard Page 2 of 2
<br /> Tracy, CA 95304
<br /> potential for groundwater flow to be toward the west to northwest — toward the nearby drinking
<br /> water wells and away from the three borings advanced east of the dispenser islands.
<br /> Your current consultant, E&HC, has done a fine job marshalling the available data to argue for
<br /> case closure as a low-risk site, and the EHD considers the arguments excellent supporting points
<br /> for a closure case built on site-specific data that characterizes the LIAR in the subsurface, but at
<br /> this time the EHD is of the opinion that the site is not adequately characterized for such an
<br /> argument. The Low-threat Underground Storage Tank Case Closure Policy (LTCP), recently
<br /> adopted by the SWRCB, requires development of an adequate conceptual site model that
<br /> assesses the nature, extent, and mobility of (a) release; if there is uncertainty of the groundwater
<br /> flow direction, and if the contaminant distribution in soil and groundwater in a potential
<br /> downgradient direction has not been assessed, how can the model be considered adequate?
<br /> E&HC has stressed that the contaminant is 'only diesel', and states that diesel is not toxic or
<br /> carcinogenic, but the LTCP does not make a diesel exception for fulfilling all the LTCP criteria.
<br /> Diesel may not be considered carcinogenic or toxic, but some of its components are, such as
<br /> naphthalene, which is a diesel component that the LTCP does consider, but it has not been
<br /> assessed. E&HC states that most, if not all, water supply wells in the area have 50-foot seals; the
<br /> EHD notes that the two closest wells are not labeled as known as having 50-foot seals.
<br /> In your Petition, you characterize your LIAR as "a small leak from a diesel dispenser island" and as
<br /> .,a little diesel', and while in the scale of such releases it may prove to be relatively small, it did
<br /> involve six dispenser islands over a linear distance of 90 feet, so it may potentially be a significant
<br /> release, and it has been assessed in only one direction. If it could definitively be demonstrated that
<br /> groundwater flows northeastward to eastward on your site, the assessment may be considered
<br /> adequate. The EHD has spent considerable time reviewing data attempting to demonstrate this,
<br /> but the data is not sufficient for the EHD to make such a demonstration; with the uncertainty, the
<br /> EHD cannot concur with your closure request.
<br /> You have filed a petition with the SWRCB to review your site for case closure, but be aware that
<br /> the EHD has thoroughly reviewed your site characteristics and is prepared to close your case
<br /> without undue delay if the impact to shallow soil and groundwater in the direction of concern is
<br /> assessed and favorable data obtained. As far as environmental assessments go, the anticipated
<br /> work is not onerous—a few grab groundwater samples should be sufficient if collected from a more
<br /> permeable shallow soil interval (the likely contaminant migration pathway) in the direction of
<br /> concern. The work plan and report of findings need not be lengthy, a few pages each should do.
<br /> You have no wells to destroy, so the longest period of time involved could well be the public
<br /> notification/participation period of 60 days, which is required for closure by either the EHD or the
<br /> SWRCB. The EHD urges you to proceed with the additional assessment work as was directed by
<br /> the EHD by letter dated 3 April 2014, a directive still in force.
<br /> If you have any questions or comments please contact Nuel Henderson at (209) 468-3436 or by
<br /> email at nhendersonAsicehd.com.
<br /> Nuel C. Henderson, Jr., PG
<br /> Engineering Geologist
<br /> c: Cori Condon, PG, CVRWQCB, 11020 Sun Center Drive#200, Rancho Cordova, CA 95670
<br /> Frank Goldman, PG, E&HC, P.O. Box 1193, Meadow Vista, CA 95722
<br /> Case Closure Denial and Directive Letter 0714
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