HomeMy WebLinkAboutGEO FOR ONSITE SEPTIC SYSTEM - SWG Letters / Memos - 2/28/2023 ev►.v%rotech EvLg Lweerti ,g
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February 28,2023 11EUEM
Dilbar Murtazina MAR 01 .2023
7600 142nd Avenue NE
Redmond,Washington 98052 By k
RE: Geotechnical Evaluation of On-Site Septic System
271 E Linda Vista Court, Union,Washington.
Parcel 32232-53-00013
To Whom It May Concern,
Envirotech Engineering (Envirotech) completed a site visit on February 23, 2023 to the property in order
to observe surface and subsurface conditions. This geotechnical evaluation addresses the proposed on-site
septic system with relation to landslide hazards on and near the property. Information collected from site
observations and field testing was completed by Michael Staten with Envirotech. We reviewed the
proposed drip system septic design,dated February 20,2023,by Jim Hunter&Associates.
Subsurface conditions were visually classified as a shallow 2-foot layer of silty sand with gravel (SM)
overlying cemented glacial till soils. The septic drainfield area is moderately sloping with grades of
approximately 22%.Critical descending slopes exceeding 40% were observed on the property,downslope
from the planned drainfield.
It is our opinion that the proposed septic system will not influence the nearby critical descending slopes
exceeding 40%, provided that vegetation remains undisturbed on the critical slopes. Earth movement
remains a potential within the critical slopes, but this feature is located outside the influence zone. The
property may or may not experience shallow landslides. However, we believe that the proposed drainfield
has a sufficient setback from the top of critical slope,and will not contribute to future landslides.
If you have any questions or need any further assistance,please contact Michael Staten at 360-275-9374.
Sincerely, APPROVED
Envirotech Engineering
MAR 1 5 2023
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Michael Staten,P.E.
Project Director
PO gox984
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Off: 360-27-5-37-4
Ctll: 360-625-6045