Thanks Gerald:
We found some site specific topo in our archives and it indeed flows south to north so I probably won’t send much south, if any. The as-builts Dan sent do show 12” for the SD to the last CB on Rachel but I’ll try to avoid going that direction, we don’t want to rip up a bunch of existing street if we don’t have to. The County has to accept flow to the north in my opinion.
Maximum block spacing?
Dan Symons
Symons Engineering Consultants, Inc.
phone: 503 760 1353
Integrity & Strength in Design
From: Gerald Fisher <gfisher@cityofmolalla.com>
Sent: Tuesday, June 23, 2020 5:45 PM
To: Dan Symons <dans@symonsengineering.com>
Cc: Larry Shirts <larrys@symonsengineering.com>; Dan Zinder <dzinder@cityofmolalla.com>
Subject: RE: Storm info for Lexington Estates
Hi Dan,
Here are the answers to the questions below.
Question 1 – According to our contouring, the topography flows from south to north towards Vick Road. Storm drainage would need to continue in that direction. If the County denies drainage into their roadway in writing then we can look at sending flows south as long as it doesn’t cause a basin transfer. In that case, it appears that the size upstream of the last manhole was not sized for the horn portion,. The main from the manhole to the CB is 10” and our minimum size for flow through is 12”. That makes sense because that area was the upper reach of the flow directly into Creamery Creek. The storm main would have to be upsized to accommodate storm flows from upstream and you would have to provide downstream calcs from the point of connection to the detention pond off of Anne Lane and beyond until the flow % is reached to verify capacity based on our storm sizing requirements. See Section 3.2.5 and 3.2.6 of the PW Standards. I don’t have records of the stormwater calc’s in our file but there may be some documents in our archives. We can look tomorrow.
Question 2 – Here is the link to the TSP. See page 50 Table 10. Local street spacing minimum is 150’ CL to CL and can be adjusted to meet the lot depths x2 for the SF homes. Example: If your lot depth is 100 feet and local street ROW is 50 feet, then 25+100+100+25 is 250 feet CL to CL.
https://www.cityofmolalla.com/publicworks/page/public-works-master-plans
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
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From: Dan Symons <dans@symonsengineering.com>
Sent: Tuesday, June 23, 2020 4:52 PM
To: Dan Zinder <dzinder@cityofmolalla.com>
Cc: Gerald Fisher <gfisher@cityofmolalla.com>; Larry Shirts <larrys@symonsengineering.com>
Subject: RE: Storm info for Lexington Estates
Thanks again Dan, I purged our archive files a few years ago so I appreciate you forwarding this. We are going to try to put together a better prelim plan for discussions with Alice on the 2nd and we have a couple of questions:
- 1. Was the storm line in Eric Drive and Anne Lane sized for the “horn” to tie in? On the surface it looks like it might be OK but I’d like to confirm. If you have Favreau’s stormwater calcs to forward I can look it up in there. Eventually we will probably calc it out ourselves but of course I’m looking for the easy button for this prelim design phase.
- 2. We looked at the Public Works Standards and didn’t find much reference to the minimum/maximum block length requirements, can you steer us to the proper location/document for that info?
