Email.Comments.3.pdfFrom:
Zulauf, JoAnne
Sent:
Monday, March 10, 2014 1:42 PM
To:
todd@toddpmacdonald.com
Subject:
b1d20131301 MacDonald SFR
Attachments:
ImpNumberl.pdf; ImpNumber2.pdf, ImpNumber3.pdf, Covenant for Rain Garden
Stormwater System (777486).doc
Todd,
The previous comments have not been addressed in the plans. The engineer has stated that the impervious surface
calculations have been updated to be consistent. I have attached copies of the areas on the March 3`d submitted plans
that are inconsistent in hopes of getting this resolved without sending out the same comments a third time. I am hoping
that the engineer can provide the consistent information and I can redline the plans and approve them.
He has stated that because he is overdesigning the rain garden "maybe 5300 sf" is being physically routed to the
Garden". While it is acceptable to allow for a small amount of uncollectible runoff, the different calculations on the
plans indicate that this total could be anywhere from 300 sf to 450 sf. This would not be an acceptable amount of
uncollected runoff. This range excludes the existing garage. Whether the rain garden is oversized or not is irrelevant.
in the submitted response to the last set of comments the engineer states the architects plans include "other little bits
of impervious area. ..that can't get collected into a storm pipe that reaches the rain garden" are not included in his
design total. New impervious surface by definitions is all new impervious surface to be constructed regardless of where
or how it is mitigated. All new impervious surface must be included in the impervious surface calculations. All new
impervious surface shall be accounted for in sizing references on plans.
Whether the rain garden is oversized or not, this does not change the requirement of an accurate total of new
impervious surface that is consistent throughout the entire plan set or change the requirement that all new impervious
surface runoff must be routed to the new rain garden. If any existing impervious surface (e g the existing garage) is
being routed to the rain garden then that also shall be noted clearly on the plans.
Perhaps there are some clarifications that will take care of this issue. For example the architect has included square
footage of an uncovered deck in his impervious surface calculations. If the deck will have an impervious surface
underneath, gravel, concrete etc. then it is correct to include this an new impervious surface. If there will not be any
impervious surface under the deck then the architect can respond to verify that the deck should not be considered
impervious it can then be excluded from the new impervious surface calculations.
I understand that because the system will be oversized it is unclear to the engineer why these numbers are
required. Bottom line is they are required by City development code. If you would like a full explanation, I will be happy
to provide one.
If all the totals had been consistent, most of these issues would be cleared up. If there are still questions regarding the
City's requirements please let me know an I will try to provide a further clarification.
I have also attached a copy of the City's rain garden covenant that must be signed and notarized and returned to the City
prior to permit issuance. The approved plans will be attached as Exhibit B.
Final review of your plans will resume once I receive the information requested.
Thank you
JoAnne Zulauf I Senior Engineering Technician
Engineering Division j City of Ldrnonds
121 S'l' Ave N I E inrionds, 11V14i 98020
c,.2'i.771.0220 x 132A I FAX 425.672.57.' 0
Joanne.Zulauf@edmondswa.gov