Minimum site-specific information

Minimum site-specific information. Minimum site-specific information. At a minimum, the site-specific geotechnical investigation shall include all of the following specified requirements, unless an alternative geotechnical investigation proposed under s. NR 512.085 (4) has been completed and has met all of the requirements of s. NR 512.085 (1) and (2) : (1) Borings. As specified in Table 1, borings sufficient to define sub-surface conditions shall be drilled both inside and outside the proposed limits of filling. (a) At a minimum, borings shall be drilled in 10 separate locations for the first 5 or less acres of the proposed fill area. Two borings shall be drilled for each additional 5 or less acres of proposed fill area. The borings shall be located on a grid pattern. All borings shall be located in or within 300 feet of the proposed limits of filling. (b) Borings shall extend a minimum of 25 feet below the anticipated sub-base grade. If the boring is located outside the proposed limits of filling, the applicable sub-base grade is the elevation of the bottom of the proposed base liner nearest to the borehole. (c) If regional information suggests that bedrock is within 50 feet of the lowest elevation of the proposed sub-base grades, one boring shall be extended at least 5 feet into bedrock. Every attempt shall be made to locate this boring outside the proposed limits of filling. Bedrock drilling shall be performed in accordance with ch. NR 141 and s. NR 507.05 . (d) Samples shall be collected and retained and boring logs shall be prepared in accordance with sub. (5) and ss. NR 507.05 and 507.14 . (e) Borings not converted to wells shall be abandoned in accordance with ss. NR 507.08 and 141.25 . (2) Wells. As specified in Table 1, wells sufficient to define the hydrogeologic and groundwater quality conditions shall be installed. At a minimum, this includes: (a) Installing observation wells to adequately define the water table surface and horizontal hydraulic gradients. At a minimum, 5 water table observation wells shall be installed for the first 5 or less acres of disposal area and one additional observation well for each additional 5 or less acres of disposal area. The observation wells shall be constructed so that the water table intersects the well screens at all times during the year. (b) A piezometer shall be installed adjacent to a water table observation well at 2 separate locations to create well nests for the first 5 or less acres of disposal area. One additional piezometer for each additional 10 or less acres of disposal area shall be installed to create additional well nests. For every 20 acres of disposal area at least one well nest shall be placed within the proposed limits of filling. (c) For proposed limits of filling located in a fine-grained soil environment, each well nest required in par. (b) shall consist of 3 wells: a water table observation well, a piezometer installed at or just below the proposed subbase grades and a deeper piezometer installed at least 15 feet below the bottom of the upper piezometer’s well screen. (d) All wells shall be located no more than 300 feet from the proposed limits of filling and at least half of the wells shall be located no more than 150 feet from the proposed limits of filling. (e) All wells shall be designed, installed, developed, documented, and sampled in accordance with ch. NR 141 and ss. NR 507.06 , 507.07 , 507.14 , 507.17 , and 507.18 . Alternative methods of well design and installation shall not be used unless they achieve comparable results and the department provides prior written approval. (3) Field direction. A professional geologist or qualified technician who is directly supervised by a professional geologist shall observe and direct the drilling of all borings and the installation, development and abandonment of all wells. A professional geologist or qualified technician who is directly supervised by a professional geologist shall also conduct all in-field hydraulic conductivity tests and visually describe and classify all of the geologic samples. (4) Laboratory and field analysis. Laboratory and field analyses shall be conducted to identify the specific geologic, hydrogeologic and groundwater quality conditions at the proposed facility as outlined below: (a) For each major soil unit encountered, at least 5 representative samples shall be analyzed for grain size distribution using mechanical and hydrometer methods and Atterberg limits as appropriate for the particular type of material. Each representative sample shall be classified according to the unified soil classification system. (b) Laboratory hydraulic conductivity tests shall be conducted on at least 2 representative samples from each major fine-grained soil unit. Tests shall be run on undisturbed samples when conditions allow. (c) The department may require that other tests be conducted as appropriate for the particular type of material. (d) An in-field test shall be conducted on each well to determine the in-situ hydraulic conductivity. The test shall be of long enough duration and include a sufficient amount of data to provide a representative estimate of the actual hydraulic conductivity. (e) After each well has been properly developed, successive water level measurements shall be taken until stabilized readings are obtained. Stabilized water level measurements shall be obtained on a monthly basis for a minimum of 6 months prior to submittal of the feasibility report. After this period, quarterly water level measurements shall be obtained for at least 4 quarters; or for contiguous expansions of existing landfills, water levels at newly installed and existing monitoring wells may be collected in conjunction with detection monitoring events. (f) Stabilized water level measurements shall be obtained on a monthly basis for a minimum of 6 months prior to submittal of the feasibility report from surface water bodies including streams, lakes, ponds, drainage ditches, and wetlands located within 1,000 feet of the proposed limits of filling. After this period, quarterly water level monitoring shall be performed for at least 4 quarters; or for contiguous expansions of existing landfills, water levels of surface water bodies may be collected in conjunction with routine monitoring events. (g) At least 4 rounds of baseline groundwater monitoring shall be performed on all observation wells and piezometers located outside the proposed limits of filling that were installed to evaluate the proposed property in accordance with s. NR 507.18 and submitted along with the feasibility report. (h) The department may require other work such as groundwater modeling, pump tests, geophysical investigations, isopach maps or a fence diagram to assess the hydrogeologic conditions at the proposed facility. (5) Sample retention. All soil and bedrock samples collected from the proposed property shall be retained in accordance with s. NR 507.05 (1) (e) , except for soil and bedrock samples collected as part of a previous geotechnical investigation and included in a report previously approved by the department. (6) Additional requirements for landfills with extended collection lines. (a) Landfills shall meet the requirements of pars. (b) and (c) where they will accept municipal solid waste and contain leachate collection lines that exceed 1,200 feet from the end of each cleanout to the toe of the opposite slope. Where the requirements of this subsection differ from other requirements of this chapter, these requirements shall take precedence. (b) A minimum of one boring in the area of each proposed cell shall be drilled to physically characterize subbase conditions for landfill foundation assessment of stability and settlement. Borings shall be extended to a minimum of 50 feet below proposed subbase grades or to competent bedrock, whichever is shallower. Borings shall include standard penetration testing. Samples shall be taken at each significant soil layer. A minimum of one sample from each fine grained layer and from each soft or compressible coarse grained layer shall be subjected to geotechnical testing to define parameters used in assessments of stability and settlement of the liner. (c) Consolidation testing data shall be included with the data summarized by major soil unit in the table required by s. NR 512.10 (2) (d) .