R 299.4906 Landfill groundwater monitoring; systems.

Rule 906. (1) A landfill groundwater monitoring system shall be installed and shall consist of a sufficient number of wells, installed at appropriate locations and depths, to yield groundwater samples from the uppermost aquifer that are in compliance with both of the following provisions: (a) Represent the quality of background groundwater that has not been affected by leakage from a unit. A determination of background groundwater quality may include sampling of wells that are not hydraulically upgradient of the waste management area where either of the following conditions exist: (i) Hydrogeologic conditions do not allow the owner or operator to determine that wells are hydraulically upgradient. (ii) Sampling at other wells will provide an indication of background groundwater quality that is as representative or more representative than that provided by the upgradient wells. In cases where the director has approved the sampling of wells that are not upgradient to determine background groundwater quality, the owner and operator shall maintain 1 or more upgradient wells to verify that the alternate wells are as or more representative. (b) Represent the quality of groundwater hydraulically downgradient of the solid waste boundary and ensure detection of groundwater contamination in the uppermost aquifer and other groundwater specified by the director. When physical obstacles preclude the installation of groundwater monitoring wells at the solid waste boundary, the downgradient monitoring system shall be installed at the closest practicable distance hydraulically downgradient from the solid waste boundary to ensure detection of groundwater contamination in the uppermost aquifer and other groundwater specified by the director. (2) The director may approve a multiunit groundwater monitoring system instead of separate groundwater monitoring systems for each type II landfill unit when the facility has several discrete units, if both of the following conditions are met: (a) Groundwater monitoring wells are not more than 150 meters from the solid waste boundary of each unit and are located on land that is owned by the owner of the unit. (b) The multiunit groundwater monitoring system is in compliance with the requirements of subrule (1) of this rule and will be as protective of human health and the environment as individual monitoring systems for each unit, based on the following factors: (i) The number, spacing, and orientation of the units. (ii) The hydrogeologic setting. (iii) The site history. (iv) The engineering design of the units. (v) The type of waste accepted at the units. (3) Monitoring wells shall be cased in a manner that maintains the integrity of the monitoring well bore hole. The casing shall be screened or perforated and packed with gravel or sand, where necessary, to enable the collecting of groundwater samples. The annular space between the bore hole and well casing above the sampling depth shall be sealed to prevent the contamination of samples and the groundwater. (4) The owner and operator shall notify the director that documentation of the design, installation, development, and decommission of any monitoring wells, piezometers, and other measurement, sampling, and analytical devices has been placed in the operating record. (5) All monitoring wells, piezometers, and other measurement, sampling, and analytical devices shall be designed, operated, and maintained so that they perform to design specifications throughout the life of the monitoring program. (6) All monitoring wells shall be designed to minimize the time that is necessary to recharge the well, given the hydraulic conductivity of the aquifer. (7) The number, spacing, and depths of monitoring systems shall be in compliance with all of the following provisions: (a) Be based upon site-specific technical information, including a thorough characterization of both of the following: (i) The uppermost aquifer, including all of the following information: (A) Aquifer thickness. (B) Groundwater flow rate. (C) Groundwater flow direction, including seasonal and temporal fluctuations in groundwater flow. (ii) Saturated and unsaturated geologic units and fill materials that overlie the uppermost aquifer, materials that comprise the uppermost aquifer, and materials that comprise the confining unit defining the lower boundary of the uppermost aquifer, including all of the following information: (A) Thicknesses. (B) Stratigraphy. (C) Lithology. (D) Hydraulic conductivities. (E) Porosities. (F) Effective porosities. (b) Be certified by a geologist. (c) Be approved by the director. Within 14 days of the approval, the owner or operator shall notify the director that the certification and approval have been placed in the operating record. (8) All wells shall be clearly labeled and shall be properly vented, capped, and locked when not in use. All wells shall be visible throughout the year. (9) The owner or operator shall not undertake well replacement, plugging, abandonment, or repair without the approval of the director or his or her designee.