Geo-tech report - additional parking along 75th.pdf� "'A IV E
NELSON GEOTECHNICAL
SOLI TES, INC.
NGA GEOTECHNICAL ENGINEERS & GEOLOGISTS
Main Office Engineering -Geology Branch
17311 — 1351" Ave NE, A-500 5526 Industry Lane, #2
Woodinville, WA 98072 East Wenatchee, WA 98802
(425) 486-1669 • FAX (425) 481-2510 (509) 665-7696 ° FAX (,509) 665-7692
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MEMORANDUM SE
DATE: September 7, 2018 11111NIEER46 OVIS10,V
TO: Mr. Derek Abbott
FROM: Maher A. Shebl, PE
Lee S. Bellah, LG
RE: Rockery Traffic Surcharge Memorandum
Abbott Residence Rockeries
16404 — 75' Place West
Edmonds, Washington
NGA File No. 9175B16
This memo presents our supplemental geotechnical recommendations and opinions regarding the
reinforced rockery construction for the residence project located at 16404 — 75"' Place West in Edmonds,
Washington.
INTRODUCTION
We have previously prepared a geotechnical engineering evaluation for the project titled "Preliminary
Geotechnical Engineering Evaluation — Abbott Residence — 16404 - 75" Place West — Edmonds,
Washington," dated March 27, 2015. We also performed part-time construction monitoring for the
residence construction and rockeries within the property. We understand that you plan on constructing an
approximately 8-foot wide by 25-foot long gravel covered parking area within the upper very eastern
portion of the property parallel to 75' Place West. We understand that the City of Edmonds has requested
our opinions and recommendations regarding potential traffic surcharge on the existing reinforced fill
rockery.
Recent Observations and Recommendations
We visited the site on August 31, 2018. We observed that the rockery in this area is approximately two
feet in exposed height. An approximately four foot tall 2H: I V slope is located immediately above the wall
that ascends to the east up to a relatively level bench area along the western shoulder A 75" Place West.
This bench is approximately 19 feet wide. The proposed gravel parking strip is setback approximately 11
feet from the 2H:1 V slope above the rockery. Based on our field measurements, it appears that the
Rockery Traffic Surcharge Memorandum
Abbott Residence Rockeries
Edmonds, Washington
NGA Project No. 9175B16
September 7, 2018
Page 2
proposed parking strip will be setback at a gradient of approximately 3H:1 V extending from the rear base
of the rockery up to the western side of the proposed parking strip.
In our opinion, it appears that the proposed parking strip along the western shoulder of 75' Place West is
adequately setback from the lower reinforced -fill rockery and should not exert any additional surcharge
loads on the rockery. We recommend that traffic surcharge loads not be allowed any closer than the
proposed setback unless a specific geotechnical evaluation is performed.
We trust this memorandum should satisfy your needs at this time. Please contact us if you have any
questions or require additional services.
NELSON GEOTECHNICAL ASSOCIATES, INC.