Operation of a Self Cleaning Wet Well – The Nitty Gritty of Rag Removal, A Case Study and Lessons Learned

The City of Aurora, Colorado recently completed two new wastewater lift stations utilizing self cleaning wet well technology. The use of self cleaning trench–type wet wells is increasing in popularity throughout the United States, but there is limited information on the operation of these types of systems. An abundance of rags, grit, solids and stringy material from the service area caused issues, including pump blockages, during operation of the lift station. The city conducted multiple tests of the self cleaning cycle to evaluate the effectiveness of rag and grit removal at different percentages of the last pump's capacity. Additionally, problems experienced during the self cleaning cycle, unique to the cleaning cycle, were also reviewed. The results of these tests, their effectiveness, and lessons learned are provided. As the popularity of trench-type self cleaning wet wells increases, other communities may find similar issues with the operation of these types of systems.