Emerging Geosynthetic Products - LK Kachhwal
Published: February 05, 2019
Emerging geosynthetic products have changed the geotechnical engineering perspective concerning soft and compressible soil conditions. The conventional approach of excavate, remove, and replace with quality engineered backfill can be very labourious, time consuming, and uneconomical. An alternate approach involves the use of high-strength geosynthetic material for reinforcement and improvement of subgrade soils. We utilized this technique to support a 40 m-diameter fuel storage tank on a geosynthetic reinforced earth foundation (GREF) that was constructed on soft and compressible soils.
In 2015 Nichols Environmental completed a geotechnical investigation, which revealed that the in situ soil conditions on site comprised compressible, soft, and high plastic black lacustrine clay mixed with organics. It was determined this upper layer of clay soil was not suitable for the foundation of the tank, and a deep pile foundation was not desired by the client due to cost and other site development constraints.
A 3.0 m-thick GREF pad was designed using eight layers of high-strength geotextile sandwiched between imported 6-80 granular (Alberta Transportation) fill material. The settlement calculations were conducted manually and using a computer model. The total maximum uniform settlement of 150 mm was predicted. During hydrostatic load testing of the tank, conducted over a period of 12-days, the measured total uniform settlement ranged between 54 mm and 122 mm, so the uniform settlement was within the predicted values during the design of the GREF.
The GREF performed satisfactorily and resulted in significant cost and time savings to the client, in comparison to a deep pile foundation strategy. A case study paper on this project will be accepted for publication and be presented at the Geosynthetics Conference, Houston, 2019.
Asphalt Flux Release - J. Zunti
Published: January 09, 2019
In October 2018, Nichols Environmental responded to an 18,000-L spill of asphalt flux (roofing tar) after two trailers detached from a haul truck along the off-ramp of Anthony Henday Drive onto Calgary Trail south. The hot tar flowed down the embankment, over a concrete retaining wall, and into a storm sewer catch basin that serviced the interchange.
Challenges for this project included a busy roadway and time restrictions, the presence of engineered fill, a retaining wall, and 275 m of affected storm line (1,000 mm in diameter). Approximately 80 m3 of impacted surface soils were removed mechanically and by hand from the embankment, and tar was removed via steam units and manually. Water samples collected at the downgradient stormwater pond indicated that no surface water had been impacted. The only remaining work to be completed in the spring of 2019 is removal of the tar from the retaining wall and hydroseeding of the remediated area.
Published: December 11, 2018
We had the opportunity to visit the Canadian Light Source facility at the University of Saskatchewan - the brightest light in Canada! The facility and people that run it are leaders in synchrotron science and are spearheading research in the mining and energy, health and life sciences, and advanced manufacturing sectors. Check out their website at https://www.lightsource.ca/.