ASTM D6286-98(2006)

The selection of particular method(s) for drilling monitoring wells (see Table 1) requires that specific characteristics of each site be considered. These characteristics would include, but are not limited to, the ambient hydrogeologic parameters and conditions existing at the site. This guide is intended to make the user aware of some of the various drilling methods available and the applications, advantages and disadvantages of each with respect to determing groundwater chemistry and other hydrogeologic properties data.

This guide can be used in conjunction with Guide D6169. There are several guides that deal with individual drilling methods (see Guides D5781, D5782, D5783, D5784, D5872, D5875, and D5876) and how to the complete them for water quality monitoring device installation (see Practice D5092).

TABLE 1 Well-Drilling Selection Guide

^A Actual achievable drilled depths will vary depending on the ambient geohydrologic conditions existing at the site and size of drilling equipment used. For example, large, high-torque rigs can drill to greater depths than their smaller counterparts under favorable site conditions. Boreholes drilled using air/air foam can reach greater depths more efficiently using two-stage positive-displacement compressors having the capability of developing working pressures of 250 to 350 psi and 500 to 750 cfm, particularly when submergence requires higher pressures. The smaller rotary-type compressors only are capable of producing a maximum working pressure of 125 psi and produce 500 to 1200 cfm. Likewise, the rig mast must be constructed to safely carry the anticipated working loads expected. To allow for contigencies, it is recommended that the rated capacity of the mast be at least twice the anticipated weight load or normal pulling load.

^B Soil = S (Cuttings), Rock = R (Cuttings), Fluid = F (some samples might require accessory sampling devices to obtain).

1.1 This guide provides descriptions of various drilling methods for environmental site characterization along with advantages and disadvantages associated with each method discussed. A comprehensive description of these drilling methods can be found in individual ASTM standards, see Section 2. This guide is intended to aid in the selection of drilling method(s) for environmental soil and rock borings and the installation of monitoring wells and other water-quality monitoring devices.

1.2 This guide does not address methods of well construction, well development, or well completion. These topics are covered in other ASTM documents, see Section 2.

1.3 This guide cannot address all possible subsurface conditions that may occur such as, geologic, topographic, climatic, or anthropogenic. Site evaluation for engineering, design, and construction purposes is addressed in Guide D420.

1.4 The values stated in SI units are to be regarded as the standard. Because dimensions of materials used in the drilling industry are given in inch-pound units by convention, inch-pound units also are used in this guide.

1.5 This guide does not specifically address methods of lithologic sample collection, such as coring, that may require the use of a specific drilling method. Other ASTM guides should be consulted for sampling methods (see Guide D6169) and equipment necessary for specific projects.

1.6 This guide does not purport to comprehensively address all of the methods and the issues associated with drilling for environmental purposes. Users should seek qualified professionals for decisions as to the proper equipment and methods that would be most successful for their site investigation. Other methods may be available for drilling and qualified professionals should have flexibility to exercise judgment as to possible alternatives not covered in this guide. The guide is current at the time of issue, but new alternative methods may become available prior to revisions; therefore, users should consult with manufacturers or producers prior to specifying program requirements.

1.7 Pertinent guides addressing specific drilling methods, equipment and procedures are listed in 2.1. A comprehensive list of guides, methods, practices, and terminology for drilling is contained in Guide D5730. Other documents covering procedures for environmental site investigations with specific objectives or in particular geographic settings may be available from federal, state, and other agencies or organizations. The appropriate agency or organization should be contacted to determine the availability and most current edition of such documents.

1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

1.9 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education and experience and should be used in conjunction with professional judgement. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process.