Wisconsin Administrative Code › Department of Transportation › Chapter Trans 207 - Design and construction of municipal highway bridges in or over navigable streams › Section Trans 207.09 - Erosion control

Current through June 24, 2024
(1) Protection of exposed earth slopes, slope
			 steepness limits, and areas of required treatment described in this section
			 constitute the minimum erosion control treatment required, although they should
			 be adequate for most streams. Consistent with sound erosion control practices,
			 however, each site shall be evaluated on its own merits and notwithstanding s.
			 Trans
			 207.02(2) (a), the area of protection
			 shall be increased to minimize siltation of navigable waters. Constructing
			 authorities shall be guided by those provisions of the Standard Specifications
			 for Road and Bridge Construction of the Wisconsin Department of Transportation
			 (Edition of 1975) regarding erosion control. Copies of this volume may be
			 obtained from the Wisconsin Department of Transportation, Construction Section,
			 P.O. Box 7916, Madison, Wisconsin 53707, and are also on file at the offices of
			 the Department of Transportation, (4802 Sheboygan Avenue, Madison), the
			 Secretary of State (244 W. Washington Avenue, Madison), and the Legislative
			 Reference Bureau (Suite 200, One East Main Street, Madison).
(2) WITHIN ACTIVE STREAM EROSION ZONE.
(a) Bridges. (See figures 1 and 2.) All
			 exposed earth slopes which are part of the highway embankment or cut in the
			 immediate structure area shall be protected with heavy riprap or equally
			 effective erosion control treatment if such slopes are steeper than 6:1. The
			 maximum earth slope steepness shall be 1-1/2:1.
(b) Culverts and arches. (See figure 3)
1. Upstream-When water velocities and/or soil
			 conditions warrant such, the upstream end shall have end walls or suitable
			 inlet devices to maintain a stabilized, non-erosive stream gradient upstream
			 and to facilitate blending of earth fill slopes to the structure. Earth fill
			 slopes shall be no steeper than 2:1 and, as a minimum, shall be blanketed with
			 topsoil and established with grass cover. If earth slopes will be exposed to
			 erodible water velocities they shall be protected with regular riprap or
			 equally effective erosion control material. Culverts and arches functioning
			 under hydraulic high-velocity, inlet-control conditions subject to soil washout
			 along the outside of the barrel shall be equipped with a suitable barrel collar
			 near the inlet end.
2.
			 Downstream-When water velocities discharging from the structure exceed that of
			 the natural current immediately downstream and erosion is probable, the
			 downstream end shall have end walls or devices to facilitate blending of
			 fill-slopes to the structure with a maximum earth-slope of 2:1. All earth
			 slopes shall be blanketed with topsoil and established with grass cover.
			 Sufficient stream bottom protection and energy-dissipation devices shall be
			 used to establish flow conditions which are compatible with the natural
			 conditions without appreciable erosion of the streambed. Such devices can be
			 regular riprap, heavy riprap, concrete pavement with or without
			 energy-dissipating blocks, ponded outlets, or combinations of these or similar
			 devices. Sufficient cut-off walls to preclude water undermining of pavement
			 slabs or the structure shall be utilized.
(c) Streambanks-All exposed earth streambank
			 slopes which are shaped, disturbed, or created to properly fit the stream to
			 the structure shall be blanketed with riprap or equally effective erosion
			 control treatment if such slopes are steeper than 4:1. The maximum slope
			 steepness shall be 2:1. All such slopes which are 4:1 or flatter shall, as a
			 minimum, be blanketed with topsoil and established with grass cover, except
			 that in areas where the curvature of the stream is such that the flow is
			 directed against the streambank, riprap or equally effective erosion control
			 treatment shall be employed. This paragraph applies to all streambanks within
			 the active stream erosion zone except in the immediate structure area where the
			 highway approach embankment or cut acts as the streambank.