05-0770 Peer Review No 1a 091007 From: Amy Head [amy@sheacarr.com]
Sent: Thursday, August 30, 2007 3:24 PM
To: Jim Gibson
Cc: Roberta Allen
Subject: Peer Samantha Ridge
??????Jim:
This is a tough one as far as knowing what you guys will accept. I see it went before the Hearing’s Examiner so I am guessing the things I want to point out have already been
reviewed. However, I am a little stumped as to why some of these things weren’t discussed. Here is what I am struggling with:
They are proposing a detention facility which I have never seen in Yelm. I know they have some perched groundwater on-site, but it seems that this is a somewhat localized
condition that can easily be avoided by locating a facility elsewhere on-site. Further, the Hearing’s Examiner specifies infiltration and the use of roof drywells for roof runoff
in the conditions. Can they do detention if the HE conditions call out infiltration? Currently, my comment letter indicates that they should revise their design to provide
an infiltration facility as well as the use of roof drywells. I indicate that they will need to coordinate with the geologist and the geotech as more testing and study may be
required since they are changing their design.
If a detention facility is ok, then I am assuming the use of a Vortechs is not for treatment. Generally, I see the use of these systems alone for treatment only when they
are upstream of infiltration. I don’t think they should be used alone in a detention system. They don’t remove enough pollutants.
I am confused by their private road. If you read the guidelines, it appears that even the private roads should be built to the local access residential road standard. What
they are proposing isn’t much bigger than an alley. I didn’t see anything about this in the Hearing’s Examiner conditions so I am assuming that their small 22 foot wide road
is approved, but I wanted to be sure.
Did the layout change since the hearing? The HE report talks about units within the floodplain but what I am looking at does not show any lots within the floodplain. They
are simply proposing some fill. I did a little fill in a floodplain in Lacey and was simply allowed to provide compensating volumes to ensure the same volume of floodplain was
available on the site. It didn’t require a FEMA map change as technically you are not changing the elevation of the floodplain. I wasn’t sure if I should note that they
need to do floodplain compensation or that they need to show proof of the LOMA that is discussed in the HE report.
Anyway, I have the letter mostly complete. I just may need to revise depending on your comments.
Amy Head, P.E.
Shea, Carr & Jewell, Inc.
2102 Carriage Dr. SW
, Bldg H
Olympia
, WA 98502
p. 360.352.1465
f. 360.352.1509
c. 360.584.3835
email. amy@sheacarrjewell.com