CORRESPONDENCE_2016-2017 - Laserfiche WebLink

Home Browse Search

SW-2 compared to SW-1, tentative indication of a release will have been identified. For the purposes of this flow event specific assessment, significantly higher will be defined by a 10% increase in the concentration of an inorganic constituent at SW-2. Vadose Zone - Because of the limited amount of vadose zone data collected from background lysimeter LZ-1, concentration limits cannot be calculated by the tolerance limit method as described above. The lack of soil pore fluids collected from either the background lysimeter or the lysimeters beneath LF-2 are due the dry nature of the soil at both the background location and beneath LF-2. The lack of sufficient soil moisture beneath LF-2 in itself is a positive indication that the liners beneath the wastes at LF-2 are intact and not releasing leachate. However, when sufficient soil water pore fluid samples are collected for statistical analysis,the inter-point tolerance limit method will be employed for the determination of inorganic concentration limits. 4.2.3 Retest Methods If a release is tentatively indicated by the criteria previously discussed for both synthetic and inorganic constituents, a series of steps will be performed to determine if the change in water quality is due to a release from the facility or from nonfacility interferences. Nonfacility interferences include natural aquifer interferences, possible upgradient discharges, sample contamination, and laboratory interferences, including transcription errors, laboratory contamination, and method or chemical interferences. If nonfacility interferences related to sampling or analysis is implicated, a statement demonstrating these conditions will be submitted as soon as the determination has been made. If a release is tentatively indicated, the analytical data will also be reviewed using professional scientific and engineering principles. If warranted, a professional opinion may be rendered that an analytical result may not be indicative of a release. In order to verify the release of a monitoring parameter or COC from the facility, statistical retests will be performed. A discrete retest method will be used to minimize the potential for false-positive indications of a release at the site. A discrete sample will be collected from the indicated monitoring point and analyzed for the parameter(s) which exceeded its concentration limit. The sample will be collected and submitted to a state-certified laboratory of the original statistical determination. Upon the collection of analytical data, the same statistical (or nonstatistical) methods, which provided the tentative indication of a release, will be conducted on the retest data. If the statistical results confirm the original tentative indication of a release, an evaluation monitoring program will also be prepared consistent with the requirements of Article 1, Sections 20420(1)(5) and 20425. For synthetic constituents, a release will be confirmed, if the VOC detected in one or both verification samples is the same VOC detected in the original sample. If the retest analytical data meet the requirements of a tentative indication of a release, an evaluation monitoring program will be proposed. The same statistical method used to establish the concentration limits will be used to evaluate retested inorganic constituents, if a particular Foothill WQPS Rev Ldoc 4-5