Turnkey solution eliminates chain and scraper downtime

Problem

The Grass Valley area of California has challenges that include mine drainage and heavy flows during the winter storm season in the Sierra Nevada foothills. On average, the city discharges 2.1 mgd to Wolf Creek, a tributary of the Bear River. In 2013, the chain and scraper clarifier system was reaching the end of its useful life, increasing the burden on the treatment system and its operators. Matters became worse when a collector system in two of the tanks became inoperable after a breakdown of the triple-output shaft drive system. The outage left just one of three secondary clarifiers operational and threatened to shut down the entire system.

Solution

The utility commissioned an upgrade to replace the chain and scraper systems, drive system, and scum pipes with new equipment from Evoqua Water Technologies. The new chain and scraper system has nonmetallic chain components with individual drives and simple lever-operated scum pipes. The technology was pioneered by Envirex, an Evoqua brand. The system’s lightweight design made installation easy and simplifies maintenance.  

Result

With the new equipment, downtime and maintenance issues have been eliminated. The system has increased the efficiency of solids removal and operating life has been extended for another 15 to 20 years. www.evoqua.com