An innovative cover system to close an ash/sludge impoundment

August 1, 2019

By Paul C. O’Malley, José L. Urrutia and Don DiGuilio The two projects (confidential client) are industrial sites consisting of coal ash and by-product sludge located in the southeastern United States. The projects included 70 and 67 acres (28 and 27 ha) in closure areas, and the waste source consisted of industrial sludge with a …

Reviving the Palos Verdes Reservoir—Part 4

By John Heap and Chris Kelsey The active site work for the Palos Verdes Reservoir’s substantial update began in late 2016, advanced primarily throughout 2018 and concluded in the second quarter of 2019 with the filling of the reservoir. The project was immense for everyone involved, and with that has come the expected excitement, challenges …

The GMA Techline

Moderated by Robert M. Koerner, George R. Koerner and Y. “Grace” Hsuan A geotextile for unpaved driveway/road? Q: Is there any point in using a 150 g/m2 (4.4 oz/yd2) nonwoven geotextile in building an unpaved gravel driveway or gravel road? If so, what should be the most important characteristics of the fabric and what are …

A minitube blanket for landfill gas collection and containment

By Stephan Fourmont, Pascal Saunier and Toraj Ghofrani Landfill gas (LFG) is produced during the decomposition of putrescible material in landfills. Often referred to as biogas, LFG is a source of odors and fugitive greenhouse gas (GHG) emissions. LFG is typically 40%–60% methane, which is 25 times more potent to affect climate change than carbon …

Stabilization of subgrade soils during Interstate 95 lane widening

By Bryan C. Gee, Eric Klein and William T. Maier The Maryland Transportation Authority (MDTA) is implementing a multiyear, multiphase project to add express toll lanes (ETLs) to Interstate 95. The ETLs are providing significant congestion relief in one of the most heavily trafficked corridors in the United States. The major modification to I-95 consists …

Geogrid reinforced soil structures reach new heights

June 1, 2019

By Sachin Mandavkar and Mehari Weldu Reinforced soil structures are geotechnical systems consisting of reinforcing elements and primarily include mechanically stabilized earth (MSE) walls and reinforced soil slopes (RSS) (Figure 1). MSE walls and RSS are constructed by placing alternating layers of reinforcement and compacted soil behind a facing element to form a composite material …

The GMA Techline

Who is doing the testing? Q: This question relates to the number of rolls to be selected as the lot sample for specification conformance testing and refers to ASTM D4354. When I look at this standard, it appears the values in Table 1 of GRI’s White Paper #10 refer to the number of units to …

Streambank restoration using engineered bank stabilization

By Jeffery T. Hoilman and Stanley M. Miller Mountain Creek flows through the community of Red Bank near Chattanooga, Tenn., to the Tennessee River. Mountain Creek has been identified by the Tennessee Department of Environment and Conservation (TDEC 2018) as a 303(d)-listed stream, meaning that its pollution exceeds the state’s standards for one or more …

Using geosynthetics in flexible airport pavements

By Benjamin Mahaffay, Jeremy Robinson, Jeffrey Gagnon and Gregory Norwood In recent years, there has been an increasing interest to improve pavement structures through mechanical stabilization by incorporating geosynthetic products within the structure. The Geosynthetic Materials Association (GMA) has identified eight categories of commercially available geosynthetics: geotextiles, geogrids, geonets, geocomposites, geosynthetic interlayers, geocells, erosion control …

Carthage Mills installs geocell in video

May 2, 2019

Carthage Mills has released a YouTube video showing the installation of a geocell on a slope. The company carries the CX and CXW Series of geocells, which are three-dimensional, expandable panels made from high-density polyethylene (HDPE). Engineers use such geocells for containment, erosion control and ground stabilization applications. They improve the structural and functional behavior …