Section R. 299.4904 - Contents of a hydrogeological reportRule 904.
(1) The purpose of a hydrogeological report for a landfill is to do all of the following: (a) To determine existing groundwater quality, including the areal and vertical extent of any groundwater contamination.(b) To determine background groundwater quality in the uppermost aquifer.(c) To determine the groundwater level and to determine compliance with the groundwater isolation requirements of these rules and, if necessary, to define engineering modifications to reduce the groundwater level.(d) To define a proposed groundwater monitoring program.(e) To define all of the following aquifers: (i) The uppermost aquifer and aquifers that are hydraulically interconnected to the uppermost aquifer beneath the facility property.(ii) Any aquifer that is utilized by type I and type IIa public water supplies, as defined in R 325.10502, within 1/2 mile of the proposed active work area.(iii) Any aquifer that is utilized by type IIb and type III public water supplies, as defined in R 325.10502, within 1,000 feet of the proposed active work area.(f) To define the areal and vertical extent of the site earth materials under the proposed facility.(2) Hydrogeological studies shall be prepared by, or under the direction of, a qualified groundwater scientist or geologist.(3) A determination of hydrogeological conditions shall cover sufficient area to allow for a definition of the potential impact of the landfill on groundwater.(4) A hydrogeological report for a landfill or other disposal area shall include all of the following: (a) A determination of the background groundwater quality.(b) A map of the site and surrounding area which is drawn to scale and which shows all of the following:(i) The distance to existing wells and the properties in the surrounding area that have potential for groundwater supplies. The map shall identify all soil borings and wells at the facility and within 1/2 mile of the site, including all domestic, municipal, industrial, oil, and gas wells for which copies of logs are available in the public record.(ii) Existing lakes or ponds.(iii) Streams, springs, or wetlands.(iv) The direction of surface drainage and the direction of groundwater movement in the site area.(v) The locations of borings, observation wells, and other well data used in the report.(vi) The topography, including predominant topographic features.(vii) The location of any existing open dump, underground storage tank, or other known or potential source of groundwater contamination.(c) Observation well records or soil borings to locate and identify aquifers beneath the facility property. All of the following shall be identified:(i) Depth to the groundwater.(iii) Vertical and horizontal groundwater flow directions.(iv) Vertical and horizontal flow rates.(d) A groundwater elevation map which is based on stabilized water level readings, which uses values contoured on an interval of not more than 1 foot, and which is referenced to United States geological survey datum. Data shall be included to determine both of the following:(i) Groundwater flow direction and possible variations in groundwater flow direction.(ii) Depth to the groundwater.(e) Evaluation of site earth materials. The evaluation shall be based on soil boring logs and the results of soil sampling from the borings to define soil and groundwater conditions at the site, including bedrock characteristics, if bedrock exists, within 50 feet of the proposed base of the fill. All of the following procedures shall be utilized in collecting this data: (i) Soil samples shall be collected by standard soil sampling techniques.Representative uncomposited soil samples shall be tested for by all of the following methods, unless other methods are approved by the director:(A) The particle size distribution, by both sieve and hydrometer.(B) For cohesive soils, the Atterberg limits under ASTM D4318-94, which is adopted by reference in R 299.4135.(C) The classification under the unified soil classification system, under ASTM D2487-93, which is adopted by reference in R 299.4135.(D) Undisturbed hydraulic conductivity under the methods approved in R 299.4920.(ii) Boring logs shall include all of the following information:(A) Soil and rock descriptions.(E) Water level measurements at the time of the boring.(iii) All soil borings that are not converted to observation wells shall be carefully backfilled with bentonite or cement grout, plugged, and recorded under part 625 of the act.(iv) All elevations shall be referenced to United States geological survey datum.(f) A series of geologic cross-sections or fence diagrams that pass through representative borings and illustrate all of the following:(iii) Soil classification.(vii) Stabilized water level readings.(viii) Proposed site grades. All of the data specified in this subdivision shall be referenced to a site map that shows the locations of all wells and borings.
(g) The nature, extent, and consequence of any mounding that results from the diversion of infiltration and surface water runoff, both during the active life of the facility and during the postclosure period.(h) A description of any proposed engineering modifications intended to modify groundwater level.(i) A determination of the horizontal and vertical flow system, and diagrams that illustrate horizontal and vertical flow directions of groundwater.(j) A proposed hydrogeologic monitoring plan that is in compliance with R 299.4905.(k) A compilation and interpretation of data, map s, and charts based on site conditions to support the conclusions and recommendations of the report.Mich. Admin. Code R. 299.4904