From: Brenda Reiner

Sent: Fri Mar 16 08:05:07 2018

To: Gerald Fisher

Subject: FW: 600 Rivers Lane

Importance: Normal

I would like to discuss this storm issue with you for Peter Burkhoff.

Brenda Reiner | Senior Engineering Technician

City of Molalla

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

Office: 503.759.0243 I Fax: 503.829.3676

From: george Snegirev [mailto:avalonengineering@wavecable.com]

Sent: Thursday, March 15, 2018 5:00 PM

To: breiner@cityofmolalla.com

Subject: 600 Rivers Lane

Brenda

I will be working on the storm water management plan for Peter Burkoff for his new residence at 600 Rivers Lane.

Do you mind answering a few questions on how this needs to be done.

To connect into the storm drainage system out in Toliver Rd seems to be not an option, so an on-site storm water facility is what will be required in this instance.

The NRCS Soil Survey shows this area to be Dayton silt loam which belongs in hydrologic soil group D, this soil group has a very slow infiltration rate.

Table 3.12 Infiltration Trench Requirements show Soils requirements (NRCS classification) of A or B for publicly maintained facilities; C soils may be used for privately owned facilities if drawdown standards are met.

Can we still have an infiltration trench in class D soils; and if possible can we use the minimum rate of 0.5 inches per hour for our design or is an infiltration test needed to be done to verify the infiltration rate.

Is this infiltration facility required for the roof runoff only or it needs to be designed for all the runoff on this site.

What storm event does this facility need to manage.

If you could provide me answers for these questions then this will first determine if the infiltration trench is feasible and then the criteria for design.

Thank you very much and I look forward to your response.

George Snegirev P.E.

103 S. First Street, Suite 205

Silverton, OR 97381

(Office) 503-874-4433

(Cell) 503-807-5048