Chapter 2 MN Construction Specification Part 642
National Engineering Handbook
INSTRUCTIONS FOR USE
MINNESOTA CONSTRUCTION SPECIFICATION 64—Wire Mesh Gabions and
Mattresses Twisted (Woven) or Welded Mesh
1. Applicability wire size or mesh openings, as applicable.
Construction Specification MN-64 is applicable to Note in table 2 of the construction
the installation of wire mesh gabion baskets and specification that only PVC coated gabion
mattresses, including bedding, filter, or geotextile mattresses are specified.
e. Details of bedding, filter material and/or
2. Material specifications geotextile including gradation for material,
The following material specifications complement compaction requirements of material, class of
Construction Specification MN-64: geotextile, and any special requirements, if
required. Refer to the respective construction
521—Aggregates for Drainfill and Filters
specifications as applicable. Both types of
MN-523—Rock for Riprap
gabions perform best when placed on
relatively smooth and unyielding foundations.
Construction Specification MN-95, Geotextile, A coarse aggregate or a stone leveling course
also complements this specification. can be successfully used under gabions to
enhance good support and grade control.
3. Included items
Items to be included in contract specifications f. Source of rock and prequalification of other
and drawings follow: material as appropriate.
a. Complete drawings showing alignment, layout, g. Rock size if different than that specified.
size of baskets or mattresses required, interior
support details, lacing, connecting or fastening h. Requirements for concrete cap, if applicable,
plans as applicable, and any other related including location and placement details.
appurtenances or details. Include and refer to Construction
Specifications MN-31 or MN-32 as necessary.
b. Gabions designated as basket or mattress, as
appropriate. Type of gabion construction: i. Rockfill and lid closure requirements for
twisted or welded mesh. gabions placed on a slope to serve as a chute
with flow down the top surface. These gabions
c. Specify in section 7 if alternate ring fasteners must be filled as densely as possible to avoid
as recommended by the manufacturer are to be movement and distortion during design flow
allowed for basket interconnection and closure events.
of tops. The specification only allows the use
of alternative ring fasteners for the assembly of j. The specified batter to the front face of vertical
empty gabion baskets or mattresses. If it is gabion walls. A minimum wall batter of 6
determined that the use of these fasteners can degrees is recommended (1 horizontal to 10
provide a minimum strength of 1,400 pounds vertical). Where possible, design stepped
per linear foot for gabions and 900 pounds per faced gabion walls instead of vertical faced
linear foot for gabion mattresses, then section walls.
7 of this specification may be used to allow 4. Construction details
their use to join gabions and to close the lids of In section 7 of construction specification MN-64,
gabions. The manufacturer's recommendations prepare and outline job specific "Construction
are to be followed concerning the proper Details" (CD) in accordance with these
interlocking of fasteners and their spacing to instructions. For ease of utilization, the use of
attain the required strength. recyclable color paper for the CD should be
d. Specify in section 7 the type of wire (plain, considered.
galvanized, or PVC coated) if specific design
requirements need to be met, coating color,
and any special requirements, such as different
NRCS-Minnesota (210-VI-NEH, May 2005) MN64-I-1