4849 SPIRE LN 2023 Geotech Report 2025-10-15

Proposed Remedial Excavation: 4849 Spire Lane, Everett, WA December 8, 2022 The excavation support and shoring system used must comply with all applicable safety requirements. If sloughing does occur below the adjacent building footing, the structure should remain stable due to previously installed pipe piles. We recommend that any sloughed area below the building footing be backfilled with CDF to restore support and fill the voids. BASELINE SURVEY AND MONITORING Ground movements may occur as a result of excavation activities. As such, survey monitoring points should be established on ground surfaces and adjacent structures within a horizontal distance equal to two times the depth of the excavation. The monitoring points should be spaced no more than 20 feet apart, and baseline data should be collected before the start of excavations. Subsequent readings should be taken twice a week during the excavation and bacicfill process. The monitoring program should include changes in both the horizontal (x and y directions) and vertical deformations. The monitoring should be performed by the project surveyor to the nearest 0.01-foot, and the results be promptly submitted to the project team for review. The results of the monitoring will allow the design team to confirm design parameters, and for the contractor to make adjustments if necessary. We also recommend that the existing conditions of the adjacent private and public properties be photo -documented prior to commencing any earthwork at the site. CONSTRUCTION CONSIDERATIONS STRUCTURAL BACKFILL After the excavation has been completed, we understand that it will be backfilled with structural fill, and the surface restored to its existing condition. Adjacent to the existing structure, we recommend that CDF be used as backfil. When CDF is not used, we recommend the imported fill consist of granular material such as WSDOT gravel borrow (WSDOT Standard Specification 9-03.14(1)), or an approved equivalent. The structural fill should be moisture conditioned to within about 3 percent of optimum moisture content, placed in loose, horizontal lifts less than 8 inches in thickness, and systematically compacted to a dense and relatively unyielding condition and to at least 95 percent of the 22-389�4849 spire lane everett_rpt.docx Page 9 PanGEO, Inc.