1029 52ND ST SW Geotech Report 2022-10-31

1.0 INTRODUCTION This report presents the results of GeoDesign's geotechnical investigation for the proposed Seahurst short plat project located northeast of the intersection of Seahurst Avenue and 52'Street SW4n,Everett,Washington. The existing site consists of two single-family residences with associated utilities at 5125 and 5133 Seahurst Avenue (Snohomish County Tax Parcel Numbers 004166-000-007-00 and 004166-000-008-00). The site location relative to surrounding physical features is shown on Figure 1. Acronyms and abbreviations used herein are defined above, immediately following the Table of Contents. 2.0 PROJECT UNDERSTANDING The proposed project consists of subdividing the two properties into a six-lot short plat that will be accessible from 52nd Street SW and 51 st Place SW(Figure 2). The proposed development will include construction of four additional single-family residences and supporting utilities. Based on the preliminary site map provided by Alpha Subdivision Pros Inc. (ASPI),the single-family residences will consist of tuck-under structures with a lower-level garage and stairs up to the main living space. We understand that LID design elements such as infiltration trenches, permeable pavement, and bioretention areas are being considered to manage stormwater generated by the proposed development. Based on the City of Everett's (City) Infiltration Feasibility Map, the site is mapped as "Potentially Feasible for Infiltration"(City of Everett, 2018a). 3.0 : PURPOSE AND SCOPE The purpose of our geotechnical engineering services was to characterize subsurface conditions and develop geotechnical recommendations for use in.the design and construction of the proposed development. The specific scope of our services is summarized as follows: • Reviewed preliminary project plans and readily available geologic information for the site vicinity. • Observed five test pits excavated within.the.project..area to depths.ranging between 4.0 and 10.0 feet BGS. • Conducted PITs in two test pits in general accordance with the 2014 Stormwater Management Manual for Western Washington (DOE, 2014), which the City has adopted. • Prepared this report that presents our findings, conclusions, and recommendations. 4:0 : r SlTECONDITIONS Site conditions were observed during our two visits to the site to mark exploration locations for utility locates and to complete the subsurface explorations. Subsurface conditions were evaluated by excavating five test pits and reviewing existing geologic maps for the project area. G EODESIGN2 1 NWHome-1-01:101618