11024 20TH DR SE 2025-01-13 - Laserfiche WebLink

Settlement Evaluation and Underpinning Recommendations Page 2 April 11,2024 11020 20th Drive Southeast,Everett,Washington RGI Project No.2013-302-4 Based on review of preliminary pile plans prepared by B2 Engineers and discussions with you (the client), our recommendations for the underpinning process are as follows: 1) Install exterior piles according to the attached plans. Piles installed on the western perimeter should be installed north to the deck column footing (non-inclusive). Piles installed on the southern perimeter should be installed from the southwest corner to the second entry way to the east(non-inclusive), 2) Verify with B2 Engineers that if the southwestern-most interior pile location (circled in red in the attached plan) is not installed, no problematic moments will be introduced in the column footing east of the southwestern entryway. 3) Once underpinning is complete, confirm no cracking or damage is observed in the interior or exterior of the units. 4) In 2 years, complete an evaluation of the interior and exterior to confirm cracking or settlement has not been observed. The pin piles should be driven to refusal.Refusal criteria for 2-inch piles for a 650 pound hydraulic hammer at 1000 blows per minute is 4 seconds per inch for 3 consecutive inches. If a 90-pound jackhammer is used, refusal criteria is 60 seconds per inch for 3 consecutive inches. Based on the borings, refusal is expected at approximately 10-15 feet below the ground surface at the foundation. Localized soil conditions may allow for variations in embedment depth. Piles are then capped and mechanically connected to the foundations. Walkway and Patio Support The walkway and patio may be supported on a minimum of 2 feet of compacted structural fill underlain by a woven geotextile.The overexcavation surface should be moisture conditioned and compacted prior to placement of the woven geotextile. RGI should be retained to observe and evaluate the repair and replacement of these soils to verify no additional over-excavation will be required during construction. Additional Services RGI is available to provide geotechnical engineering and construction monitoring services during underpinning and earthwork for the patio and walks. The integrity of the earthwork and construction depends on proper site preparation and procedures. In addition, engineering decisions may arise in the field in the event that variations in subsurface conditions become apparent. Limitations This letter is the property of RGI,3Stripe Management,and its designated agents.Within the limits of the scope and budget, this letter was prepared in accordance with generally accepted geotechnical engineering practices in the area at the time this letter was issued. This letter is intended for specific application to the subject property in Everett, Washington, and for the exclusive use of 3Stripe Management and its authorized representatives. No other warranty, expressed or implied, is made.Site safety, excavation support,and dewatering requirements are the responsibility of others. The analyses and recommendations presented in this letter are based upon data obtained from the explorations performed on site. Variations in soil conditions can occur, the nature and extent of which may not become evident until construction. If variations appear evident, RGI should be requested to reevaluate the recommendations in this GER prior to proceeding with construction. II 1 MI �Ei 2- I1y