Emergency Pipeline Rehabilitation Ensures Raw Water Supply to Domtar Paper Mill

The Southwest Arkansas Water District (SWAWD) delivers up to 70 million gallons per day (mgd) to the Domtar Paper Mill (Domtar) in Ashdown, Arkansas, via a raw water canal. The canal traverses a small stream near the paper mill by two parallel inverted siphons: a 60-inch reinforced concrete pipe (RCP) and a 66-inch corrugated metal pipe (CMP). In 2016, SWAWD observed an apparent leakage of water from the pipelines into the stream. The age of the pipes (40–50 years) suggested that the wall integrity of the CMP and the joint integrity of the RCP were compromised and were the sources of the leak. Because the canal is the sole source of process water for the paper mill, maintaining uninterrupted flow to the mill and ensuring the long-term integrity of the canal walls was paramount. While evaluating repair options, a sinkhole near the leak (approximately 500 gallons per minute) developed, suggesting the leak was worsening and risking the integrity of the canal walls; thus, an emergency design/build approach was taken. Available options included pipeline repair, pipeline removal and replacement, and construction of a new pipeline(s) with abandonment in-place of the old pipelines. A synopsis is provided on the emergency construction techniques used in implementing the chosen alternative: lining the pipes with cured-in-place pipe (CIPP) and constructing headwalls on the both sides of the pipes. Installation of a 70 mgd bypass system consisting of eight 18-inch pumps, earth/rock cofferdams, and dewatering pumps allowed site access while maintaining the provision of raw water supply downstream.