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HomeMy WebLinkAboutRS_Geotechnical summary letter_20220522_v1 17425 NE Union Hill Road, Suite 250 Redmond, Washington 98052 425.861.6000 May 20, 2022 Topgolf 8750 North Central Expressway Suite 1200 Dallas, Texas 75231 Attention: Bryan Musgrove (Topgolf)/Erik Silvis (Arco/Murray) Subject: Summary Letter Geotechnical Construction Phase Services Topgolf Renton Landing Project 780 Logan Avenue North, Renton, Washington GeoEngineers File No. 23325-001-01 Permit No. R-412301 INTRODUCTION This letter presents a summary of GeoEngineers’ construction observation services for the TopGolf Renton Landing development project located in Renton, Washington. Our services for this project were completed in general accordance with our Services Agreement executed on June 25, 2021. The project involved the development of a low-rise structure, an outfield area consisting of turf and enclosed with nets supported by poles up to 170 feet in height, and surface parking. The site is bounded by North 8th Street to the north, Park Avenue North to the east, office and parking structures to the south, and Logan Avenue North to the west in Renton, Washington. OBSERVATIONS GeoEngineers visited the site on an intermittent basis between June 17, 2021, and April 28, 2022, to observe Geopier installation and testing, major utility installation, foundation subgrade and backfill, outfield construction, parking, and sidewalk, drilled shaft for net pole and helical anchors installation, observe temporary erosion control, and attend pre-construction meetings. Detailed reports of our construction observation services were presented in our daily field reports for the project, GI-001 through GI-018, GT- 001 through GT-138, and DS_FR 001 through DS_FR012. Copies of these field reports were provided to Topgolf, ARCO/Murray, Geopier Northwest, Judge Netting, and the City of Renton. This summary letter focuses on the following geotechnical inspection items: Topgolf| May 20, 2022 Page 2 File No. 23325-001-01 ■ Observation of rammed aggregate pier installation for building footing subgrade improvement. ■ Building foundation soil bearing verification. ■ Verify fill and compaction. ■ Utility and subsurface drainage installation. ■ Outfield construction and settlement verification. ■ Parking lot subgrade preparation. ■ Drilled shaft and helical anchor installation. ■ Temporary erosion control and groundwater discharge monitoring. Observation of rammed aggregate pier Installation for building footing subgrade improvement We observed the installation of ground improvement consisting of rammed aggregate piers (i.e. Geopier®) beneath the shallow foundations supporting a low-rise structure building. Approximately 808 geopiers were completed for the project from June 29, 2021, and July 21, 2021. Installation of geopiers consisted of using a hollow mandrel driven to the required depth and having the aggregate placed into the mandrel and compacted by raising the redriving the mandrel in lifts until the geopier is constructed. The daily field reports, GI-001 through GI-018, and as-built geopiers constructed at the site were submitted to Geopier Northwest (ground improvement designer), Topgolf, ARCO/Murray, and the City of Renton, to ensure that the design intent was met. Geopier Northwest submitted a letter of acceptance of the installed geopiers dated August 9, 2021. Building foundation soil bearing verification We observed the building foundation subgrade during our site visits from June 17, 2021, and September 17, 2021. Based on our observations, the soils at the foundation subgrade elevation consisted of silty sand with gravel (existing fill) and aggregate from stone columns installation. Based on the letter of acceptance of the rammed aggregate pier ground improvement by Geopier Northwest, the foundation subgrade soils that we evaluated are capable of providing an allowable static bearing pressure of 4,500 pounds per square foot (psf) for spread footings. Verify fill placement and compaction We observed and verified the placement of fill and compaction of the material during our site visits. Based on our observations, it is our opinion that fill placement and compaction was installed in general accordance with the project plans and specifications. Utility and subsurface drainage Installation We observed utility installation during our site visits from June 18, 2021, and January 24, 2022. The utilities installation completed at the site consisted of excavation, subgrade evaluation, installation of respective utilities, and trench backfill. Perforated subsurface footing drains were installed around the building and French drainpipe was installed at the site property limits with the Boeing facility located at the south central side of the project. Topgolf| May 20, 2022 Page 3 File No. 23325-001-01 Based on our observations, it is our opinion that the utilities and subsurface drainage were installed in general accordance with the project plans and specifications. Outfield construction and settlement verification We observed the construction of the outfield during our site visits from August 3, 2021, and April 5, 2022. The outfield construction consisted of outfield structures including 11 concrete targets, drainage systems, electrical installation, and pavement/turf subgrade grading. Targets construction work consisted of excavations, subgrade, and backfill evaluations. During outfield grading, two settlement markers were installed and monitored to evaluate settlement. No significant settlement was observed at the outfield. Proof roll tests were completed for the outfield subgrade and subbase preparation prior to the pavement placement. Proof rolls were performed with a fully loaded dump truck driving at speed limit less than 5 miles per hour. Based on our observations, it is our opinion that the outfield construction was completed in general accordance with those portions of the project plans and specifications that pertain to our services. Parking lot subgrade preparation We observed the construction of the parking lot constructed on site during our site visits. The construction of the parking lot consisted of exposing the firm subgrade and placing compacted base coarse fill. Proof roll and compaction tests were performed prior to the placement of the asphalt pavement. Based on our observations, it is our opinion that the construction of the parking lots was completed in general accordance with the project plans and specifications that pertain to our services. Drilled shaft and helical anchor installation A total of 25 drilled shafts were installed for the installation of net poles between March 10, and April 8, 2022. The drilled shaft for net pole installation consisted of drilling with a temporary casing, a 4- or 5-foot-diameter vertical hole to the required depth, installing the pole base and then placing concrete from the bottom of the hole with a tremie connected to a concrete truck pump. Centralizers were placed halfway of the pole base to ensure the net pole was centered. At the request of the General contractor, we observed installation of helical anchor at the corner poles 1, 11, 15, and 25. Helical anchors for net cables were installed at various depth reaching between 4,000 foot- pounds to 4,500 foot-pounds (ft-lbs) per designer specifications, Engel and Company Engineers. Based on our observations, it is our opinion that the drilled shaft for net pole installation and helical anchors for net cables were completed in general accordance with the project plans and specifications and the designer’s recommendations. Temporary erosion control and groundwater discharge monitoring Temporary erosion and sediment controls (TESC) was monitored during each site visit by GeoEngineers. A Certified Erosion and Sediment Control Lead (CESCL) from GeoEngineers also completed a once per week site inspection per the projects Washington State Department of Ecology Construction Stormwater General Topgolf| May 20, 2022 Page 4 File No. 23325-001-01 Permit number WAR30928. The contractor implemented TESC measures, as necessary, to prevent turbid water and soils from leaving the site. Based on our observations, it is our opinion that the TESC measures were in accordance with the project plans, specifications, and guidance established under the project General Permit. A CESCL from GeoEngineers also monitored the water quality of groundwater removed from the subsurface using well points and discharged to the City of Renton stormwater system and groundwater removed from excavations and drilled shafts using sump pumps and discharged to the ground surface of the site periodically during the project. Based on our observations and groundwater quality monitoring, it is our opinion that the groundwater discharge was completed in accordance with the project plans, specifications, and guidance established under the project General Permit. CONCLUSIONS Based on observations and evaluations completed for the project, we conclude that the work discussed herein for the for the TopGolf Renton Landing development project has been completed in accordance with the intent of our recommendations and the City of Renton approved project plans and specifications. We trust this letter meets your current needs. Please call if you have any question regarding this letter. Respectfully submitted, GeoEngineers, Inc. Lucy Hoch, PE King H. Chin, PE Geotechnical Engineer Principal RN:LH:KHC:tjh One copy submitted electronically Disclaimer: Any electronic form, facsimile or hard copy of the original document (email, text, table, and/or figure), if provided, and any attachments are only a copy of the original document. The original document is stored by GeoEngineers, Inc. and will serve as the official document of record.