Supplemental Explanation in Support of BMPs in C&D ELG and NSPS February 15, 2012

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Responses specific to UWAG concerns in EPA’s Responses to Comments Document

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1. Not feasible or desirable to channelize flow in all situations, so control of stormwater 

volume and velocity within the site is not appropriate.

Pg. 25

Comments Response:

“EPA acknowledges one commenter’s concern about regulating peak flow rates. In the nonnumeric minimum controls, the following control measure addresses this issue as follows, 

“control stormwater discharges, including both peak flowrates and total stormwater volume, to 

minimize erosion at outlets and to minimize downstream channel and streambank erosion 

(Section X.B. of the preamble).” EPA notes that while this requirement applies to all regulated 

sites, EPA understands that for some projects, such as linear utility projects, it is common 

practice to avoid channelizing flow and to instead utilize dispersion or other techniques to 

manage construction stormwater. It is EPA’s expectation that projects that do not channelize 

flow through the construction of conveyances such as channels, ditches, slope drains, etc., 

would not need to implement specific controls, such as stabilized outlets, to manage peak 

flowrates and stormwater volumes to minimize erosion and outlets and to minimize downstream 

channel and streambank erosion. EPA considers the use of dispersion or diffuse discharge 

through perimeter controls as adequate controls for this requirement. The regulation of 

discharges that occur after construction activity is outside the scope of the final rule. No further 

response necessary.” (emphasis added)

Pg. 148

Comment Response:

“EPA does not fully understand commenter’s concern about the need for discharge rate control 

in areas where there are no water courses. In such areas, this condition would not exist and the 

need to control the rate of discharge would not exist. With respect to linear projects, the need for 

discharge rate control would not be needed if water were not being impounded or concentrated 

or conveyed in channels, ditches, etc. In general, this requirement is linked to the need to 

control discharges from basins and impoundments so that large volumes of water are not 

causing scouring of the receiving stream. It seems that this would not occur at many linear 

projects and EPA would not expect these types of controls to be required in these instances.” 

(emphasis added)

2. Minimizing soil compaction should not be a requirement in areas where soil is 

intended to be compacted, e.g., stabilized pads and access roads.

Pg. 541

Comment Response:

“The rule language at 450.21(a)(7) regarding soil compaction now states that permittees should 

“Minimize soil compaction and, unless infeasible, preserve topsoil.” EPA notes that the 

“minimize soil compaction” language is meant to apply to those areas of the site where soil 

compaction is not necessary for structural or stability concerns. For example, EPA would not 

expect permittees to minimize compaction in areas, such as where roads, foundations, utility 

tower pads, footings or other structures are to be built, or on embankments, where soil 
Supplemental Explanation in Support of BMPs in C&D ELG and NSPS February 15, 2012

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compaction is necessary by design. Rather, this requirement is intended to apply to other areas 

of the site, such as those where vegetation is to be preserved. Minimizing soil compaction 

reduces the amount of runoff and erosion that occurs, thereby reducing the amount of pollutants 

in the discharge.” (emphasis added)

3. Minimizing exposure of stormwater to building materials is not appropriate for 

materials that are intended to be exposed, e.g., poles and towers.

Pg. 541

Comment Response:

“In terms of minimizing exposure of building materials, building products, construction wastes, 

trash, landscape matarials, fertilizers, pesticides, herbicides, detergents, sanitary waste and 

other materials present on the site to stormwater, EPA acknowledges that this will not be 

feasible for some materials and on some projects. For example, some building materials are 

intended to be exposed to precipitation following construction. An example would be steel used 

to construct an electric utility tower or a pre-cast concrete bridge segment. In these cases, EPA 

would not expect that controls would be implemented to minimize exposure to precipitation 

since this would likely be infeasible since these materials, due to their size, could not be placed 

under cover. Another example would be pipeline sections that are stored on-site or near a site 

prior to placement in the ground. Providing cover for these materials would likely be infeasible 

due to their size. Some materials, such as stone and brick, are inert and are likely not to 

produce pollutants if exposed to precipitation. EPA expects that permitting authorities will apply 

discretion in applying this provision of the regulation to require minimizing exposure only to 

those materials for which it is feasible and for those materials that are likely to be pollutant 

sources.” (emphasis added)

4. Soil stabilization is not appropriate for some areas, such as dirt access roads, that are 

intended to remain un-vegetated.

Pg. 135

Comment Response:

“The requirement to stabilize has been revised for the final rule. The final rule states that 

permittees are required to, at a minimum, initiate soil stabilization measures immediately 

whenever any clearing, grading, excavating or other earth disturbing activities have permanently 

ceased on any portion of the site, or temporarily ceased on any portion of the site and will not 

resume for a period exceeding 14 calendar days. Stabilization must be completed within a 

period of time determined by the permitting authority. In arid, semiarid, and drought-stricken 

areas where initiating vegetative stabilization measures immediately is infeasible, vegetative 

stabilization measures must be initiated as soon as practicable. EPA disagrees that stabilization 

should not be required until the overall project is complete as that would leave the soil exposed 

for an open ended period of time when construction activity is not ongoing. EPA acknowledges 

that some portions of some projects are intended to be left unvegetated or unstabilized following 

construction. An example would be a dirt access road or a utility pole pad where the final plan 

calls for the area to remain a dirt road or an unstabilized pad. EPA does not expect temporary or 

permanent stabilization measures to be applied to these areas unless required by the permitting 

authority.” (emphasis added)