Unsaturated Zone Monitoring

An owner or operator subject to 310 CMR 30.650 shall establish an unsaturated zone monitoring program which shall include the following: (1) The owner or operator shall monitor the soil and soil-pore liquid to determine whether hazardous constituents migrate out of the treatment zone. (a) In the land treatment license, the Department shall specify the hazardous constituents to be monitored. Except as provided in 310 CMR 30.655(1)(b), the owner or operator shall monitor for all the hazardous constituents identified pursuant to 310 CMR 30.652(2). (b) The Department may require monitoring for principal hazardous constituents (PHCs) in lieu of the constituents specified pursuant to 310 CMR 30.652(2). PHCs are hazardous constituents contained in the wastes to be land applied at the unit that are the most difficult to treat, considering the combined effects of degradation, transformation, and immobilization. The Department may establish PHCs if the Department determines, based on waste analyses, treatment demonstrations, or other data, that effective degradation, transformation, or immobilization of the PHCs will assure at least equivalent levels of treatment for the other hazardous constituents in the waste. (2) The owner or operator shall install an unsaturated zone monitoring system that shall include both soil monitoring using soil cores and also soil-pore liquid monitoring using devices such as lysimeters. The unsaturated zone monitoring system shall consist of a sufficient number of sampling points at appropriate locations and depths to yield samples that: (a) Represent the quality of background soil-pore liquid quality and the chemical make-up of soil that has not been affected by leakage from the treatment zone; and (b) Indicate the quality of soil-pore liquid and the chemical make-up of the soil below the treatment zone. (3) The owner or operator shall establish a background value for each hazardous constituent to be monitored pursuant to 310 CMR 30.655(1). The license shall specify the background value for each hazardous constituent or specify the procedures to be used to calculate the background values. (a) Background soil values may be based on a one-time sampling at a background plot that is on the site of the facility and that has characteristics similar to those of the treatment zone. The Department shall specify in the land treatment license the number of samples to be taken. In no case shall less than three samples be taken. (b) Background soil-pore liquid values shall be based on at least quarterly sampling for one year at a background plot having characteristics similar to those of the treatment zone. (c) The owner or operator shall express all background values in a form suitable for the determination of statistically significant increases to be determined pursuant to 310 CMR 30.655(6). (d) In taking samples used in the determination of all background values, the owner or operator shall use an unsaturated zone monitoring system that is in compliance with 310 CMR 30.655(2). (4) The owner or operator shall conduct soil monitoring and soil-pore liquid monitoring immediately below the treatment zone. The Department shall specify the frequency and timing of soil and soil-pore liquid monitoring in the facility license after considering the frequency, timing, and rate of waste application, and the soil permeability. The owner or operator shall express the results of soil and soil-pore liquid monitoring in a form suitable for the determination of statistically significant increases to be determined pursuant to 310 CMR 30.655(6). (5) The owner or operator shall use consistent sampling and analysis procedures that are designed to ensure sampling results that provide a reliable indication of soil-pore liquid quality and the chemical makeup of the soil below the treatment zone. At a minimum, the owner or operator shall implement and document procedures and techniques for: (a) Sample collection; (b) Sample preservation and shipment; (c) Analytical procedures; and (d) Chain-of-custody control. (6) Using a statistical procedure specified in the land treatment license, the owner or operator shall determine whether there is a statistically significant increase over background values for anyhazardous constituent to be monitored, pursuant to 310 CMR 30.655(1), below the treatment zone each time he conducts soil monitoring and soil-pore liquid monitoring pursuant to 310 CMR 30.655(4). In the land treatment license, the Department shall specify a statistical procedure which shall provide reasonable confidence that migration from the treatment zone will be identified, shall be appropriate for the distribution of the data used to establish background values, and shall provide a reasonable balance between the probability of falsely identifying migration from the treatment zone and the probability of failing to identify real migration from the treatment zone. (a) In determining whether a statistically significant increase has occurred, the owner or operator shall compare the value of each constituent, as determined pursuant to 310 CMR 30.655(4), to the background value for that constituent, using the statistical procedure specified in the land treatment license. (b) Within a reasonable time period after completion of sampling, the owner or operator shall determine whether there has been a statisticallysignificant increase below the treatment zone. The Department shall specify that time period in the land treatment license after considering the complexity of the statistical test and the availability of laboratory facilities to perform the analysis of soil and soil-pore liquid samples. (7) If the owner or operator determines, pursuant to 310 CMR 30.655(6), that there is a statistically significant increase of hazardous constituents below the treatment zone, he shall: (a) Notify the Department immediately by the quickest available means and also notify the Department in writing within seven days; the notification shall indicate what constituents have shown statistically significant increases; and (b) Within 90 days of determining that there is such a statistically significant increase, submit to the Department an application for a land treatment license modification to modify the operating practices at the facility in order to maximize the success of degradation, transformation, or immobilization processes in the treatment zone. (8) If the owner or operator determines, pursuant to 310 CMR 30.655(6), that there is a statistically significant increase of hazardous constituents below the treatment zone, he may demonstrate to the Department that a source other than licensed land treatment units caused the increase or that the increase resulted from an error in sampling, analysis, or evaluation. Such a demonstration shall be in addition to, and not in lieu of, submitting a land-treatment license modification pursuant to 310 CMR 30.655(7)(b). If such a demonstration is made to the satisfaction of the Department, and the Department so determines in writing before the expiration of the 90 day period specified in 310 CMR 30.655(7)(b), the owner or operator need not submit a land treatment license modification application. If such an application is submitted, it may be withdrawn upon a written determination by the Department that the owner or operator has made this demonstration to the satisfaction of the Department. In making such a demonstration, the owner or operator shall: (a) Within seven days of determining a statistically significant increase below the treatment zone, notify the Department in writing that he intends to make a determination pursuant to 310 CMR 30.655(8); and (b) Within 90 days of such a determination, submit a report to the Department demonstrating that a source other than the regulated unit(s) caused the increase or that the increase resulted from error in sampling, analysis, or evaluation; and (c) Within 90 days of such a determination, submit to the Department an application for a license modification to make any appropriate changes to the unsaturated zone monitoring program at the facility, unless the Department has determined in writing that such an application need not be submitted; and (d) Continue to monitor in compliance with the unsaturated zone monitoring program established pursuant to 310 CMR 30.655.