Project Description
Issaquah, WA – A 25+ lot residential plat constructed above the shores of Lake Sammamish with a highly irregularly sloped site caused a number of problems for the various construction crews involved. The site inclined uphill away from the lake and had multiple areas over a 40% slope and was underlain by silty sand with a high silt content, which also presented problems. Modular block walls were needed with structural fill and placed behind the wall to build the main road connecting the top of the slope to the lower section. The Riley Group, Inc., (RGI) was there on-site to observe the construction of the walls, make sure drainage was properly installed, and to ensure that the structural fill was compacted to adequate standards. RGI also observed the installation of all site utilities and backfilling. The native silty sands remained moist, even through the summer dry periods and in many cases, additional material was imported to maintain site stability. RGI observed all sediments placed on-site to confirm that they were suitable and would remain sustainable for future development.
Scope of Work
Included completion of the following geotechnical construction monitoring observations – site clearing and stripping; structural fill compaction testing; utility trench installation and backfill testing; modular block wall construction; detention vault subgrade and backfill; drainage installation verification and erosion control. Daily field reports were provided to the client outlining RGI’s observations, field testing results and recommendation, a final report was provided at the end of the project for reference as well.
