Natural Attenuation Monitoring (NAM) and Post Active Remediation Monitoring (PARM) for the Petroleum Restoration Program are governed by Chapter 62-780, Florida Administrative Code (F.A.C.), and other rules, laws and documents referenced therein. Specifically, Chapter 62-780.680, F.A.C., "No Further Action and No Further Action with Controls," Chapter 62-780.690, F.A.C., "Natural Attenuation Monitoring" and Chapter 62-780.750, F.A.C., "Post Active Remediation Monitoring," although requirements listed in other sections of the rule also may apply.
If chemical treatment is involved, there may be a period of Active Remediation Monitoring (ARM), while the active chemicals used in treatment return to pre-remediation levels. The specific analytes and concentrations will be based on the chemical treatment used, and will be outlined in the Remedial Action Plan prior to implementation. When ARM has ended, PARM will begin as outlined above.
Natural Attenuation Monitoring
NAM sampling will be performed following site assessment (if no active remediation is required), or following completion of PARM. NAM involves ongoing groundwater monitoring at varying intervals (see Sampling Frequency below). NAM is allowable only if free product is not present (or it is not feasible to be removed) and if contaminated soil is not present in the unsaturated zone or will not leach to groundwater based on SPLP analysis.
Prior to implementing NAM or PARM sampling, as part of the RAP, site assessment report, of final O&M report, the ATC should submit a plan that outlines what wells will be sampled, what analytes will be included, and action levels that will require re-sampling of monitoring wells or a re-evaluation of the remedial strategy. Action levels are typically considered to be NADCs for source wells, and GCTLs for TPOC wells. If these action levels are exceeded, the ATC should be re-sampling the well within 30 days to confirm the exceedance, and determining what changes to the sampling plan may be required in the associated report.
A minimum of two monitoring wells is required for NAM/PARM sampling, at least one well within the area(s) of highest groundwater contamination, and at least one downgradient point of compliance. Groundwater elevation readings should be taken from at least three monitoring wells in order to determine groundwater flow direction during each sampling event.
Typically, at least a few additional impacted wells and one upgradient monitoring well are sampled during NAM/PARM, at least annually, if not more frequently. Additional downgradient TPOC wells may also be samples if the groundwater flow direction is highly variable. The upgradient monitoring well is important if the groundwater flow direction varies, and to ensure no upgradient impacts are mingling with the plume.
Analytes selected for NAM/PARM sampling will be based on previous assessment data. Any analytes that have exceeded CTLs historically should be included in laboratory analysis. If analytes have not reported previous CTL exceedances, or have remained below GCTLs for several previous events, they can be removed from the sampling requirements. Note that all wells and all analytes must have at least two consecutive clean sampling events before they can be removed from the sampling requirements.
If confirmatory soil sampling is required, laboratory analytical requirements should be selected based on the previous assessment data, as noted for groundwater sampling above.
NAM Sampling Frequency
Initial NAM sampling should be performed on a quarterly basis, as long as hydrocarbon concentrations are showing a measurable decrease. If hydrocarbon concentrations appear to be stabilizing, after two years of quarterly NAM, or if concentration modelling is performed that shows natural attenuation will last more than 5 to 10 years, then NAM can be performed at greater intervals. Long-term NAM typically transitions to semi-annual sampling for two to four years, then annual sampling. If NAM is expected to last greater than 10 years, then biannual sampling may be performed. If the results of NAM sampling show that the site may be approaching closure, more frequent NAM sampling can be resumed.
Monitoring Report Review and Approval
NAM and PARM reporting should include quarterly reports referencing the associated quarterly (and semi-annual for NAM) sampling events, as well as an annual report that documents details of the associated sampling event, as well as discussing the results of the other sampling events during that year and what trends in concentrations can be determined. The annual report should also include recommendations for continuing sampling, changing frequency, changing wells/analytes, etc.
If the Purchase Order task includes both field work and a technical report, then deliverable reviews for completeness should be completed within ten (10) days of receipt of the deliverable. This determination of “complete” does not necessarily mean that the deliverable will not need any further revision; it means only that all required information to support work completed for invoicing appears to be present. The technical report deliverable should not be approved until all of the required information and documentation is included and is correct. This means that all tables and maps are correct and up to date, that all required backup information (e.g., soil boring logs, well installation logs, laboratory analytical sheets, chains of custody, sampling logs) is included and complete, that the document text accurately presents and describes the results, and that conclusions and recommendations are included. If the document is deficient in an area that should have been addressed, then the Agency Term Contractor must correct the deficiency at no additional charge.
After each interim or final deliverable has been reviewed, the Site Manager must send written notice of deliverable acceptance (for completeness – not full review) or approval, as applicable, to the Contractor within the required time frames. See the Report Turnaround Times Table for site manager time frames for review of technical report deliverables. If any of the work was unacceptable, then the letter must also specify what corrections or additions the Contractor must make, or specify what reductions will be made to the Purchase Order.
Generally, routine quarterly NAM, O&M and PARM reports are not required to be signed and sealed by a licensed professional if everything is proceeding as planned and there are no professional recommendations for corrective action or NFA/SRCO. However, when recommendations for NFA/SRCO or corrective action are included in these reports, such as changes to the monitoring program, modifications to the remediation system or adjustments to the milestone schedule, then they should be reviewed, signed and sealed by the appropriate licensed professional. In all cases, the applicable standard templated report cost applies.
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