NR 151.24(10)(a)1.1. Be vegetated. However, where appropriate, non-vegetative measures may be employed to prevent erosion or provide for runoff treatment, such as rock riprap stabilization or check dams.
NR 151.24 NoteNote: It is preferred that tall and dense vegetation be maintained within the swale due to its greater effectiveness at enhancing runoff pollutant removal.
NR 151.24(10)(a)2.2. Carry runoff through a swale for 200 feet or more in length that is designed with a flow velocity no greater than 1.5 feet per second for the peak flow generated using either a 2-year, 24-hour design storm or a 2-year design storm with a duration equal to the time of concentration as appropriate. If a swale of 200 feet in length cannot be designed with a flow velocity of 1.5 feet per second or less, the flow velocity shall be reduced to the maximum extent practicable.
NR 151.24 NoteNote: Check dams may be included in the swale design to slow runoff flows and improve pollutant removal. Transportation facilities with continuous features such as curb and gutter, sidewalks or parking lanes do not comply with the design requirements of this subsection. However, a limited amount of structural measures such as curb and gutter may be allowed as necessary to account for other concerns such as human safety or resource protection.
NR 151.24(10)(b)(b) Exemptions.
NR 151.24(10)(b)1.1. Notwithstanding par. (a), the department may, consistent with water quality standards, require other provisions of this section, in addition to swale treatment, be met on a transportation facility with an average daily traffic rate greater than 2500 and where the initial surface water of the state that the runoff directly enters is any of the following:
NR 151.24(10)(b)1.a.a. An outstanding resource water.
NR 151.24(10)(b)1.b.b. An exceptional resource water.
NR 151.24(10)(b)1.c.c. Waters listed in section 303 (d) of the federal clean water act that are identified as impaired in whole or in part, due to nonpoint source impacts.
NR 151.24(10)(b)1.d.d. Waters where targeted performance standards are developed pursuant to s. NR 151.004.
NR 151.24(10)(b)2.2. The transportation facility authority shall contact the department’s regional storm water staff or the department’s liaison to the department of transportation to determine if additional BMPs beyond a water quality swale are needed under this paragraph.
NR 151.24 HistoryHistory: CR 00-027: cr. Register September 2002 No. 561, eff. 10-1-02; CR 09-112: cr. (1) (bm) Register December 2010 No. 660, eff. 1-1-11.
NR 151.241NR 151.241Post-construction performance standards.
NR 151.241(1)(1)General. In ss. NR 151.241 to 151.249, “post-construction site” means a construction site subject to regulation under this subchapter, after construction is completed and final stabilization has occurred.
NR 151.241(2)(2)Applicability. Sections NR 151.241 to 151.249 apply to a transportation facility post-construction site that is or was subject to the construction performance standards of s. NR 151.23, except any of the following:
NR 151.241(2)(a)(a) A transportation facility post-construction site with less than 10 percent connected imperviousness, based on the area of land disturbance, provided the cumulative area of all impervious surfaces is less than one acre. However, the exemption of this paragraph does not include exemption from the protective area standard of s. NR 151.245.
NR 151.241(2)(b)(b) Reconditioning or resurfacing of a highway.
NR 151.241(2)(c)(c) Minor reconstruction of a highway. Notwithstanding the exemption under this paragraph, the protective area performance standard in s. NR 151.245 applies to minor reconstruction of a highway.
NR 151.241(2)(d)(d) Transportation facility construction projects that are part of a larger common plan of development, such as a residential or industrial development, that are in compliance with the performance standards of subch. III.
NR 151.241(2)(e)(e) Routine maintenance if performed for storm water conveyance system cleaning.
NR 151.241(3)(3)Storm water management plan. The responsible party under s. NR 151.22 shall develop and implement a written storm water management plan for each transportation facility post-construction site and shall incorporate the requirements of ss. NR 151.242 to 151.249.
NR 151.241(4)(4)Maintenance of effort. For non-highway transportation facility redevelopment sites and highway reconstruction where the redevelopment or reconstruction will be replacing older development or highway that was subject to post-construction performance standards of this chapter in effect on or after October 1, 2004, the responsible party shall meet the total suspended solids reduction, peak flow control, infiltration, and protective areas standards applicable to the older development or highway, or meet the redevelopment or highway reconstruction standards of ss. NR 151.242 to 151.249, whichever are more stringent.
NR 151.241 HistoryHistory: CR 09-112: cr. Register December 2010 No. 660, eff. 1-1-11.
NR 151.242NR 151.242Total suspended solids performance standard.
NR 151.242(1)(1)Requirement. Except as provided in sub. (3), BMPs shall be designed, installed, and maintained to control total suspended solids carried in runoff from the transportation facility post-construction site. BMPs shall be designed in accordance with Table 1., or to the maximum extent practicable as provided in sub. (4). The design shall be based on an average annual rainfall, as compared to no runoff management controls.
NR 151.242(2)(2)Non-highway transportation redevelopment and highway reconstruction. Except as provided in s. NR 151.241 (4), the non-highway transportation facility redevelopment and highway reconstruction total suspended solids reduction standard of Table 1. applies to non-highway transportation facility redevelopment and highway reconstruction.
NR 151.242(3)(3)Delayed implementation. For municipalities that are regulated under subch. I of ch. NR 216 and for transportation facilities under the jurisdiction of the department of transportation for maintenance purposes that are located within municipalities regulated under subch. I of ch. NR 216, the highway reconstruction total suspended solids performance standard first applies January 1, 2017.
NR 151.242(4)(4)Maximum extent practicable. If the design cannot meet a total suspended solids reduction performance standard of sub. (1), Table 1., the storm water management plan shall include a written, site-specific explanation of why the total suspended solids reduction performance standard cannot be met and why the total suspended solids load will be reduced only to the maximum extent practicable. The department may not require any person to exceed the applicable total suspended solids reduction performance standard to meet the requirements of maximum extent practicable.
NR 151.242 NoteNote: Pollutant loading models such as DETPOND, SLAMM, P8, or equivalent methodology may be used to evaluate the efficiency of the design in reducing total suspended solids. Information on how to access these models is available from the department’s storm water management program at dnr.wi.gov. Use the most recent version of the model and the rainfall files and other parameter files identified for Wisconsin users unless directed otherwise by the regulatory authority.