The Rocky Mountain Arsenal (RMA) originated as a chemical weapons manufacturing center to support WWII military activities. From 1952 to 1982, portions of the Arsenal were leased to Shell Oil Company for the manufacturing of pesticides and herbicides. Beginning in 1974, Interim Response Actions (IRA) were designed and implemented to protect public health, the surrounding community and the environment from Arsenal contamination. Contaminants at the site include pesticides, heavy metals and chemical warfare material. The RMA is an Environmental Protection Agency National Priorities List hazardous waste site that is being remediated per the Record of Decision that was signed in 1996. Based on our previous experience at the site, Terracon was selected to provide environmental services pertaining to the installation of eight 2-inch diameter stainless steel monitoring wells at the Lime Basins site to in the delineation of dense non-aqueous phase liquid (DNAPL). Terracon proposed to complete the casing and well installation at night due to daily temperatures exceeding 90 degrees during August. The Terracon team included a supervising geologist responsible for borehole logging, documentation, environmental compliance and QA/QC, as well as an industrial hygienist responsible for health and safety monitoring. The work was completed in two separate phases. In the first phase Terracon utilized a Drill Systems AP1000 dual-wall percussion hammer drill rig with an OSHA-trained six-man field operation team to perform the installation of the monitoring well completion casings which penetrated two layers of crushed recycled concrete (Biota Barrier Material). During the second phase of the project, Terracon mobilized a CME-75 using hollow-stem augers with an OSHA-trained five man field operation team to perform the installation of the DNAPL monitoring wells, which required drilling through potentially agent-contaminated material. The teams complied with detailed health and safety, environmental compliance and QA/QC requirements. Over 700 man-hours of intrusive activity were successfully performed while under Level-B personal protective equipment (PPE) conditions.