NCS000402_29_SW BMP FENCING REQUIREMENTS

GENERAL BARRIER REQUIREMENTS
The provisions of this specification shall control the design of fences for
Stormwater water quality devices. These design controls are intended to
address safety issues by limiting access to wet ponds, dry ponds, and other
stormwater quality best management practices (BMPs).
Stormwater quality BMPs that incorporate a temporary or permanent pool depth
of 24" shall be provided with a fence or barrier which shall comply with the
following:
The top of the barrier shall be at least 48 inches above grade measured
on the side of the barrier which faces away from the BMP. The maximum
vertical clearance between grade and the bottom of the barrier shall be 2
inches measured on the side of the barrier which faces away from the
BMP.
2. Openings in the barrier shall not allow passage of a 4-inch-diameter
sphere.
3. Solid barriers such as masonry or stone, are not allowed in lieu of fences;
however, access gates are to be provided at approved locations.
4. Where the barrier is composed of horizontal and vertical members and the
distance between the tops of the horizontal members is less than 45
inches, the horizontal members shall be located on the BMP side of the
fence. Spacing between vertical members shall not exceed 1.75 inches in
width. Where there are decorative cutouts within vertical members,
spacing within the cutouts shall not exceed 1.75 inches in width.
5. Where the barrier is composed of horizontal and vertical members and the
distance between the tops of the horizontal members is 45 inches or
more, spacing between vertical members shall not exceed 4 inches.
Where there are decorative cutouts within vertical members, spacing
within the cutouts shall not exceed 1.75 inches in width.
6. Maximum mesh size for chain link fences shall be a 2.25-inch square
unless the fence is provided with slats fastened at the top or the bottom
which reduce the openings to not more than 1.75 inches.
7. Where the barrier is composed of diagonal members the maximum
opening formed by the diagonal members shall not be more than 1.75
inches.
8. The entire barrier shall be installed at the same elevation and on the
outside of the access bench (if a pond) or perimeter of the BMP, where
possible.

Access gates shall comply with Items 1 through 7 above, and shall be equipped
to accommodate a locking device. Gates shall open outward away from the BMP
and shall provide a twenty foot minimum entrance opening. The gate and barrier
shall have no opening greater than 0.5 inch within 18 inches of the release
mechanism and hinges.
MATERIALS
Chain link
The wire shall be a minimum 9 gauge thickness. The posts shall be a
minimum 1-7/8" diameter with a 16 gauge wall thickness. Wire and framework
shall be a dark or earth tone color using either a Polyvinyl chloride (PVC) or
polyester color coating. Uncoated galvanized wire and framework is not
acceptable. Terminal posts shall be set in a minimum 8" diameter by 30" deep
hole using 3,000 psi concrete.
Vinyl
Pickets, rails, and posts fabricated from PVC extrusion. The PVC extrusions
shall comply with ASTM D 1784, Class 14344B and have the following
characteristics:
Specific Gravity (+/- 0.02)
1.4
Using 0.125 specimen Izod impact ft. lbs./in. notch
23.0
Tensile strength, PSI
6,910
Tensile modulus, PSI
336,000
Flexural yield strength, PSI
10,104
Flexural modulus, PSI
385,000
DTUL at 264 PSI
670C
Posts shall be placed 24" — 36" in the ground with 3,000 psi concrete
Decorative Wire
Panels: Infill wire galvanized coated steel ASTM A641-Class III, (1.0 oz/ft2)
with minimum weld strength of 80,000 psi. 6-gauge .192" [4.9mm]
horizontal wires and 4-gauge .225" [5.7mm) vertical wires connected
at every intersection by electric resistance welding in accordance
with all requirements in ASTM Al85.
Rails: Decorative rail 1-3/16" (30mm) X 1-1/2" (38mm) 16 gauge [0.060"
(1.65mm)] thick galvanized steel channel per ASTM A525, having a
50,000 psi (344 MPa) yield strength and G90 zinc coating, 0.90 oz/ft2
(0.27 kg/M2)
Posts: Galvanized square steel tubular members manufactured per ASTM
A-787 having a 45,000 psi (310 MPa) yield strength and G90 zinc
coating, 0.90 oz/ft2). Zinc coating inside and outside, Minimum post

size2" (50 mm), having 16 gauge wall thickness [0.060" (1.65 mm)]
weighing 1.94lb/ft (2.887kg/m).
Finish: All mesh, channels, posts, fittings and accessories polyester coated
individually after drilling and layout, to ensure maximum corrosion
protection. All metal shall have a polyester resin based power
coating applied by a electrostatic spray process, to a minimum
thickness of 2.5 (.0635 mm) mils. The finish shall be baked in a
4,500F (2320C) (metal temperature) oven for 20 minutes.
Ornamental
Pickets: Square Solid Bar, ASTM A 36, hot rolled structural quality steel,
60,000 psi (372 MPa) tensile strength, 36,000 psi yield strength.
Size pickets - 3/4" (75 mm). Space pickets 3-15/16" maximum (100
mm) face to face. Attach each picket to each rail with 1/4" (6 mm)
industrial drive rivets. Size 1" long.
Rails: 1-1 /2" (38mm) x 1-3/8" (35mm) x 1-1 /2" (38mm), 11 gauge [0.120"
(3.05mm)] thick galvanized steel "U" channel per ASTM A-653 or
ASTM A-607, having a 50,000 psi (344 MPa) yield strength and G90
zinc coating, 0.90 oz/f12 (0.27 kg/M2). Punch rails to receive pickets
and rivets and attach rails to rail brackets with 2 each, 1/4" (6 mm)
industrial drive rivets. Size # 4 Steel for rail produced under ASTM
A446.
Posts: Galvanized square steel tubular members manufactured per ASTM
A-787 having a 45,000 psi (310 MPa) yield strength and G90 zinc
coating, 0.90 oz/fl2).
Finish: All mesh, channels, posts, fittings and accessories polyester coated
individually after drilling and layout, to ensure maximum corrosion
protection. All metal shall have a polyester resin based power
coating applied by a electrostatic spray process, to a minimum
thickness of 2.5 (.0635 mm) mils. The finish shall be baked in a
4,500F (2320C) (metal temperature) oven for 20 minutes.
Wood
Acceptable wood fencing materials include low -density cedar, western red
cedar, Northern White Cedar, redwood, and cypress hardwoods. Grade of
wood shall be Standard and Better with limited defect characteristics on the
one face. Wood may be finished with paint or stain.
Treated Pine is acceptable and shall be Kiln dried wood pressure treated with
ACQ (Alkaline Copper Quaternary) preservative and stainless steel or hot -dip
galvanized fasteners and fittings.

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Ornamental
Chain Link
Wood
Decorative Wire
Vinyl