Section Trans 207.09 - Erosion control(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.(3) OUTSIDE ACTIVE STREAM EROSION ZONE. (a) Embankments-For roadway approaches to the structure between the active stream erosion zone and the floodplain limit as described under s. Trans 207.02, maximum steepness of fill slopes and minimum erosion control measures shall conform to Table 1. TABLE 1
Embankment Material | Maximum Side Slope Steepness | Minimum Erosion Control |
Clays | 31/2:1 | Topsoil, Fertilizer, Grass Cover |
Silt-Silty Clays | 3:1 | Topsoil, Fertilizer, Grass Cover |
Silty Sand or Fine Sand | 21/2:1 | Topsoil, Fertilizer, Grass Cover |
Sand or Sand and Gravel | 21/2:1 | Topsoil, Fertilizer, Grass Cover |
Rock Fragments | 11/2:1 | Normally Needs No Erosion Cover |
(b) Overflow Sections-When water will periodically overtop the road, from the regional or lesser floods, constructing authorities shall evaluate the frequency of overtopping, probability of road washout, and the probable detrimental effects of such a washout, including siltation of sensitive environmental and other areas. When the probable adverse effects are demonstrably worse than would be expected from the natural stream actions at equivalent flood stages, sufficient erosion control measures shall be employed to control or diminish the washout.(c) Roadside and crossroad drainage discharging onto floodplain or into navigable waters-Roadside ditches in the flood plain shall, as a minimum, be covered with topsoil and established with grass. Mulching or other treatment, as necessary, shall be used to control erosion until grass is established. For ditch grades steeper than 1%, and where erosive soil conditions exist, combinations of sod, paved ditch, riprap, check dams or other similar devices shall be used as necessary to preclude, as far as practicable, siltation of navigable waters. Areas where roadside drainage discharges onto the floodplain or into the stream shall be provided with suitable erosion control devices to maintain a stable, non-erosive condition.Wis. Admin. Code Department of Transportation Trans 207.09
Cr. Register, June, 1981, No. 306, eff. 7-1-81; correction in (1) made under s. 13.92(4) (b) 6, Stats., Register March 2012 No. 675.