pln20140022-Tiersma%20SP-request2.pdfX. I z•'A
121 5"' Avenue North, Edmonds WA 98020
Phone: 425.771,0220 e Fax: 425.771.0221 e Web: www.edrnondswa.gov
DEVELOPMENT SERVICES DEPARTMENT o PLANNING DIVISION
PUBLIC WORKS DEPARTMENT e ENGINEERING DIVISION
1'1c. ig9'3
October 6, 2014
Mr. Jeffrey Treiber
Email: jefft@lsaengineering.com
SUBJECT: REQUEST FOR ADDITIONAL INFORMATION FOR PROPOSED SHORT PLAT
LOCATED AT 22318 92od Ave W
FILE NO. PLN20140022
Dear Mr. Treiber:
During staff's review of the plans and documents resubmitted on September 10, 2014 in association with a two -
lot short plat application located at 22318 92'ld Ave W, it was determined that additional
information/clarification is necessary. Please provide responses to the following items at your earliest
convenience so that staff s review of the proposal can continue:
The submittal contains a geotechnical report (dated 8/28/2014) that describes three test pits dug on the subject
site. One test pit, EP-2, is described as having Vashon Advance Outwash down to 8 feet below ground surface
(Bgs). A sample from this test pit was collected at 4 feet bgs and taken to the lab for a grain size
analysis. Based on the NRCS soil triangle, the sample classifies as sand, which according to the 2005 Ecology
stormwater manual, has a design infiltration rate of 2 inches per hour. If the area in and around test pit EP-2 was
used for infiltration, it would be considered feasible.
The geotech report describes the underlying soil for test pits EP-1 and EP-3 as Vashon Lodgement Till down to
6 or 7 feet. This till generally has a much lower infiltration rate than the outwash shown in test pit EP-2. No
grain size analyses were done on soil samples from EP-1 or EP-3. The drainage system on the plan sheets show
drywells for the planned two lots located in the vicinity of test pits EP-1 and EP-3. Since the infiltration rates
for these areas have not been assessed and the fact that they are in till, which will have a much lower infiltration
rate than the outwash, feasibility has not been demonstrated.
Please assess the infiltration rates for the EP-1 and EP-3 test pits and/or resubmit plans showing proposed
infiltration systems in the vicinity of ER-2. Please submit the requested information to the Planning Division as
soon as possible so that staff may continue processing your application. Please keep in mind that a complete
response to this information request must be received within 90 days or the application will lapse.for lack of
information (ECDC 20.02.001D). Thus, your application will expire if the requester) information is not
received by January 5, 20I5.
If you have any questions, please do not hesitate to contact me by phone at (425) 771-0220 or by email at
jeanie.mcconiiell@edinondswa.gov.
Sincerely,
J anie McConnell
Engineering Program. Manager
c: File No. PLN20140022