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Fact Sheet No. 5 For Dairies page 2 Soil Borings a :f Soil borings can be completed with a drill rig or with direct-push technology. An alternative is to use a backhoe to construct trenches that can be used to examine site conditions and to collect soil samples. A qualified consultant can recommend the choice of technology based on expected site conditions and on cost F and time considerations. The consultant can also recommend the placement and number of soil borings.' If a drill rig is used; continuous coring is recommended to allow an accurate assessment of soil conditions; an alternate but inferior method is to have a geologist log cuttings to evaluate the soil profile. When using a 7 drill rig, soil samples can be collected at selected intervals by using a drive sampler. If direct-push technology is used, a cross section of the soil column is obtained inside plastic tubes that can then be sectioned to obtain soil samples to send for analysis. Evaluation of Soii Sam ]es Soils from borings or excavations can be visually and tactually assessed in the field by a qualified geologist or $ soil scientist (reference ASTM Standard D2488 "Practice for Description and Identification of Soils - Visual- Manual Procedure"). Samples can be analyzed in a laboratory to evaluate clay and gravel content (reference ASTM.Standard D422 "Particle Analysis of Soils"). Samples to be evaluated for nitrogen should be analyzed for nitrate (NO3) and for total Keljdahl Nitrogen (TKN) by a state-certified laboratory using approved methods. There are also a number of soils tests that can be run to assess engineering properties of soils that may be useful in evaluating suitability of sites for buildings or other facilities. Evaluation of Groundwater Initial information on expected groundwater conditions can often be obtained from regional sources such as state or county agencies or irrigation districts. Local information may be available from wells constructed at nearby properties. Leaving a backhoe excavation open overnight may indicate if the groundwater elevation is higher that the base of the excavation. However, obtaining site-specific groundwater information generally requires the installation of monitoring wells. In some cases, temporary monitoring wells can be installed using direct-push technology, but such wells may.not be allowed in some counties and will generally. not be adequate for long-term monitoring. Permanent monitoring wells are usually installed with a drill rig and must meet county construction and administrative requirements. A minimum of three wells is generally required in order to assess groundwater gradients and evaluate upgradient ("background") water quality. Well head elevations need to be surveyed to a common reference point (usually mean sea level) and the depth,to water needs to be periodically recorded (usually at the time of sampling) to establish groundwater gradients. Water samples should'initially be analyzed for standard minerals, total dissolved solids (TDS), and nitrogen- containing compounds to obtain information that can be evaluated to assess impacts to water quality. An ongoing groundwater monitoring program may be focused at parameters of most concern (for example, TDS and NO3) for periodic sampling and involve only an occasional wider range of tests. Presentation of Results A report should be prepared describing the field investigations and presenting the reported analytical results for samples submitted for analysis. Figures should be used to identify the locations of soil borings and sample 1 collection. Photographs may be used to supplement the figures. Soil profiles should be presented graphically using boring logs. Groundwater gradient information should be presented in figures and tables and regional and local groundwater information should be summarized in a narrative format. Reported analytical results should be summarized in tables and graphs and the laboratory reports should be included as an appendix. A grain size distribution chart is useful for presenting results of clay and gravel content assessments of soil ` samples. 31 FS-45B.DOC d