This report documents the activities performed during and the results obtained from the arsenic removal treatment technology demonstration project at the Village of Pentwater, MI facility. The objectives of the project were to evaluate: (1) the effectiveness of Kineticofs FM-260-AS treatment system using MacroliteR media in removing arsenic to meet the maximum contaminant level (MCL) of 10 Eg/L, (2) the reliability of the treatment system for use at small water facilities, (3) the required system operation and maintenance (O and M) and operator skill levels, and (4) the capital and O and M cost of the technology. The project also characterized water in the distribution system and residuals generated by the treatment process. The types of data collected included system operation, water quality, process residuals, and capital and O and M cost. After review and approval of the engineering plan by the State, the FM-260-AS treatment system was installed and became operational on November 22, 2005. The system consisted of one 96-in x 96-in steel contact tank and two 60-in x 96-in steel pressure tanks configured in parallel. Each pressure tank was loaded with 40 ft(sup 3) of Macrolite (Trade Name) media to which filtration rates up to 9.3 gpm/ft(sup 2) were applied The system used an existing chlorination system to oxidize As(III) and Fe(II) and the contact tank to improve the formation of As(V)-laden iron particles prior to filtration. An iron addition system was installed midway through the study to improve arsenic removal. On average, the system operated at approximately 350 gal/min (gpm) for 5.1 hr/day, producing 39,185,000 gal of water through December 8, 2006. This average flowrate corresponded to a contact time of 6.8 min and a filtration rate of 8.9 gpm/ft(sup 2). Several problems were encountered during the demonstration study, including programmable logic controller (PLC) settings, backwash and service flowrates, media loss, influent pressure spikes, and chlorine addition. The actions taken to address these problems are detailed in the report.