Herrera Comments.7.12.16.pdfJuly 12, 2016
City of Edmonds Public Works Department
Engineering Division
121 5th Avenue North
Edmonds, WA 98020
Attn: JoAnne Zulauf
Subject: Stormwater Plan Review of Mueller 4 -lot Short Plat (PLN2015-0007)
Dear Ms. Zulauf:
A portion of the following comments from Herrera (dated 4/25/16) on the Mueller 4 -lot Short
Plat have been addressed in the 6/24/16 resubmittal. Comments in blue (dated 7/12/16)
have been addressed in the resubmittal. Comments in red (dated 7/12/16) have not been
addressed in the resubmittal or are new comments based on the resubmittal.
1. The Stormwater Site Plan report (4/7/16), WWHM output report (4/7/16), Sheet C3.0
(4/6/16), and Sheet C3.1 (4/6/16) contain different rain garden bottom areas. Please
update for consistency.
7/12/16 - The rain garden dimensions have been removed from the Road, Drainage
and Utility Plan C3.0 (6/24/16), but are consistent in the Stormwater Site Plan report
(6/9/16), the WWHM Output Report (6/9/16), and the Raingarden Plan and Details
C3.1 (6/24/16).
Stormwater Site Plan report (6/9/16), WWHM Output Report
(6/9/16), and Raingarden Plan and Details (6/24/16)
Rain ga.rd.en...1........ ....... 12' x 12'
......... ......... _....�................ .�. __ .......
Rain garden 2 10' x 10'
garden arden 3 10' x 10'
I�---�-�--------______.._.._......____..................
Rain garden 4 10' x 10. .' ...............
Rain garden 5 12' x 12'
2. The top and bottom elevations and groundwater elevation for Rain Garden 4 are
inconsistent between the comment response letter (4/6/16), Sheet C3.0 (4/6/16), and
Sheet C3.1 (4/6/16). Please update for consistency.
2200 Sixth Avenue i Suite 1100 i Seattle, Washington i 98121 i p 206 441 9080 i f 206 441 9108
PORTLAND, OR i MISSOULA, MT i OLYMPIA, WA I WINTHROP, WA I BELLINGHAM, WA
Stormwater Plan Review of Mueller Short Plat
July 12, 2016
Page 3
6. The test pit locations have not been provided as referenced in the geotechnical
report. Please provide Plate 2 to verify the test pit locations. Grain size distributions
from the test pits also has not been provided (see comment #9 under status of
previous comments below).
7/12/16 1.....ocatioiii for a total of '7 test (pits have now been provided. T13..1 4 cai n be
matched with IRain Car -dein i. "ri::,..101 can ibe nTnatched with Rahn Garden 2. TP..102 cairn
be matcll-ned with IRain Cairdern 3. ""i -est Ipits wenn not Iplaced at the exact locations of
Raiin-n Cai den°n 4 or Raiirn Carden !iii however, TP 103 and .TP -105 weire excavated in the
vicirnity of tll°ne proposed raiirn gairdens.
7/12/16 - Grain size distributions were provided for TP -102 and TP -103 as well as TP -1
and TP -3, but have not been provided for TP -101, TP -104, TP -105, or TP -2.
7. For bioretention facilities/rain gardens, the Edmonds Stormwater Supplement
(Appendix C) states that there shall be one test pit per 5,000 square feet of
contributing area; however, only three test pits were included in the geotechnical
investigation
7/12/16 1.....ocatiorns for a total of '7 test Ipits II°nave now been Ipiroviided,
8. Post construction soil quality and depth is described on Sheet 3.0, but is not currently
mentioned in the Stormwater Site Plan report.
7/12./116 - most coins tn~uvuction soul quality and delpdh has beern added to MR#5 of the
for nwaten° Site I11.arn report.
9. Rain Garden sizing
The geotechnical report does not contain all the site characterization criteria found in
Volume III, Section 3.3 of the SWMMWW. The design infiltration rate used in the
modeling is from two Test pit sample. The location and depth of these test pits as well
as the grain size distribution are not included on the submittal. For design purposes,
soil samples must be collected at the location of the proposed bioretention/rain
gardens at or below the proposed depth of the native soil bioretention soil interface.
7/12/16 - Locations for a total of 7 test pits have now been provided. Depth
information is included with all 7 test pits.
7/12/16 - Grain size distributions were provided for TP -102 and TP -103 as well as TP -1
and TP -3, but have not been provided for TP -101, TP -104, TP -105, or TP -2.