Gather your information first. You'll need to know the author of the method, the title of the method, the publishing website, the URL, the publication date (if available) and the date you accessed the information. In this example, the methods are developed by a committee, so there is no author, but the website publisher is ASTM International. The title should include the document number and the title of the method.
Cite in Chicago style by putting a footnote in-text and a bibliography entry on the works cited page. Both entries will look the same. You need the title, the website name, the access date and the URL. For example: "ASTM D 4318 -10 Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils," ASTM International, accessed July 5th, 2011, http://www.astm.org/Standards/D4318.htm.
Cite the ASTM method as title, main website, website publisher, date, medium and access date in MLA format. For example: "ASTM D 4318 -10 Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils," astm.org. ASTM International, n.d. Web. 5 July 2011. For the in-text citation, MLA style just asks that you include the first piece of information from the works cited page in the text of the paper --- in this case, the title of the ASTM method.
Cite in APA style with the author or website publisher, the publication date if available, the title and the URL. For example: ASTM International (n.d.). ASTM D 4318 -10 Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils. Retrieved from http://www.astm.org/Standards/D4318.htm. Cite the method as an in-text citation by putting the first portion of the title and "n.d." in parentheses. For example: (ASTM D 4318-10, n.d.).