The letters, memoranda, and other documents below provide clarification on various topics relating to Resource Conservation and Recovery Act (RCRA) test methods.

• Department of Transportation (DOT) letter regarding samples preserved according to EPA requirements 
• DOT letter regarding the inconsistency between EPA and DOT requirements for headspace in volatile organic samples
• Memo to Regions: Use of Hydrochloric Acid (HCl) in digests for ICP-MS analysis 
• Memo to Regions: Spiking (Prior To vs After Sample Drying) Issue in SW-846 Organic Extraction Methods 
• Memorandum of Clarification Regarding Use of SW-846 Methods