Walls and culverts

October 1, 2010  |  Q&A: GMA Techline

GMA techline answers from Bob Koerner RE: Walls and culverts What, if anything, do wall contractors typically do to attach their wall to concrete culverts that intersect the face of an MSE wall? In this instance, we’re dealing with rock-filled baskets on the face. (Cole | Idaho) Reply: You ask…
Read More
Textured HDPE?

April 1, 2010  |  Q&A: GMA Techline

From the GMA Techline Subject: Textured HDPE? We are looking at a stormwater basin about 2-3 acres in size with a 20-30ft side slope at 4:1. We are using 60-ml HDPE smooth and it will be covered with sand. The pond will be partially filled with water most of the time. Will the sand stay … <di…
Read More
Difficult lining task

April 1, 2010  |  Q&A: GMA Techline

From the GMA Techline Subject: Lining task Please find attached some recent pictures of an aluminum storage tank in one of our ongoing projects. Initially, we proposed to line the tank with a 2mm-thick HDPE sheet based on its chemical resistance. The tank is already fabricated with carbon steel by o…
Read More
Veneer stability

April 1, 2010  |  Q&A: GMA Techline

From the GMA Techline Subject: Veneer stability I have a question about veneer stability in moving earth upslope vs. downslope. In the downslope equations in GRI18, how is the lack of a buttressed passive wedge accounted for in the factor of safety (FS) equations during placement of soil? I think I …
Read More
Questions about GM/GCL composite liners

April 1, 2010  |  Q&A: GMA Techline

From the GMA Techline Subject: 3 questions How do I approach designing/specifying GM/GCL composite liners for MSW landfills? Do I simply adopt the GM13 standard, which is based on fundamental research, and then double-check that the leachate leakage rate is within acceptable limits for my specific p…
Read More
CQA test frequency for geomembranes and geocomposites

October 7, 2009  |  Q&A: GMA Techline

From the GMA Techline Subject: CQA test frequency for geomembranes and geocomposites I have comments from a state agency concerning CQA test frequencies and field tests conducted on geocomposites. The questions I have are: What are the typical frequencies used for CQA testing of geomembranes and geo…
Read More
HDPE welding

October 7, 2009  |  Q&A: GMA Techline

From the GMA Techline Subject: HDPE welding [We are] seeking information that would assist on welding 60-mil white HDPE above 104°F. We have successfully demonstrated in the past with destructive and nondestructive testing welds that would exceed project specifications. We are currently on a lar…
Read More
Installing prefabricated vertical drains

October 7, 2009  |  Q&A: GMA Techline

From the GMA Techline Subject: Geocomposite question We are looking into installing prefabricated vertical drains to relieve excess pore water pressure for a surcharge fill. Following the information listed in Designing with Geosynthetics, 5th Edition, the statement 1-2 meters is the typical spacing…
Read More
GSI/GRI-GG5 and ASTM D6706

October 7, 2009  |  News, Q&A: GMA Techline

GMA techline answers from Bob Koerner Subject: GG5 I referenced GSI/GRI–GG5 on a segmented retaining wall system spec and need to know if this is correct. Supposedly on your website this standard was crossed out and noted to refer to ASTM D6706. Should I replace GG5 with the ASTM standard? Ple…
Read More
The difference between strength parameters

June 1, 2009  |  News, Q&A: GMA Techline

By Timothy D. Stark Q: What is the difference between the strength parameters c and ø, and a and δ? A: Good question because these parameters are frequently used interchangeably. c and ø, and a and δ are shear strength parameters used to represent the strength/failure envel…
Read More