From: Gerald Fisher

Sent: Mon Jan 30 13:15:37 2017

To: Jason Clifford

Subject: RE: digesters

Importance: Normal

Thanks Jason. Will be good to get some of this stuff built and online.

Regards,

Gerald Fisher, P.E. | Public Works Director

City of Molalla

117 N Molalla Ave. | PO Box 248 |Molalla, OR 97038

Office: 503.829.6855 | Direct: 503.759.0218

CONFIDENTIALITY NOTICE: The information contained in this email message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient and have received this communication in error, please contact the sender by reply email and destroy all copies of the original message. Thank you.

From: Jason Clifford [mailto:jclifford@cityofmolalla.com]

Sent: Monday, January 30, 2017 12:38 PM

To: Gerald Fisher <gfisher@cityofmolalla.com>

Subject: digesters

Hello Gerald,

Ryan was here on Thursday. I told him I’d email you about the digester project. I recommend (2) 20,000 gallon digesters, (3) blowers; one for each digester and a backup. The three blowers should be valved so each digester can use any of the three. A submersible pump in the skimmings wet well to pump to the digesters. Repiping of the backwash and drain lines from the filters; too much clear water to the digesters will thin out the solids. Pipe from the digesters to the side road northwest of filter #2. And an FKC screw press. (2) digesters is good for maintenance, decanting and emergency storage, if needed. I’ll have a chemical supplier come and perform jar testing to get the right polymer for flocculation. After that, I’ll dial the screw press. Ideally, we would want to see about 20% dried solids (cake), to reduce dumping fees. BOD and TSS are not required for digester sizing as they’re just aerated holding tanks until the contents go through the screw press. I would usually run my press all week and turn it off on the weekends to fill the digester with fresh solids and decant as needed.

Thanks,

Jason