Case Study - October 2019

Interested in Treatment?

Get Treatment articles, news and videos right in your inbox! Sign up now.

Treatment + Get Alerts

Turnkey solution eliminates chain and scraper downtime


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.


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.  


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.


Comments on this site are submitted by users and are not endorsed by nor do they reflect the views or opinions of COLE Publishing, Inc. Comments are moderated before being posted.