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

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40 CFR 450.21(d) Pollution Prevention Measures. Design, install, implement, and 

maintain effective pollution prevention measures to minimize the discharge of pollutants. 

At a minimum, such measures must be designed, installed, implemented and maintained 

to (1) Minimize the discharge of pollutants from equipment and vehicle washing, wheel 

wash water, and other wash waters. Wash waters must be treated in a sediment basin or 

alternative control that provides equivalent or better treatment prior to discharge.

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(1) This BMP controls or minimizes the discharge of stormwater from the site. 

Wash waters can contain sediment and other pollutants. If these wash waters are not properly 

managed, then pollutants contained in the wash waters can be discharged. Requiring that 

permittees properly manage wash waters would reduce the discharge of pollutants from the site.

The requirement that wash waters be treated in a sediment basin or alternative control allows 

for removal of sediment and other pollutants through settling. Examples of alternative controls 

that may be appropriate include wheel wash stations, sediment traps and filter berms. Directing 

wash water to sumps or pits where the water can evaporate or infiltrate may also be acceptable 

in certain cases. It may also be appropriate to direct wash waters to vegetated areas where the 

water can be filtered and infiltrate. The specific controls for a given project are not mandated, 

but rather can be specified by the permitting authority.

(2) What EPA does not mean by this requirement. 

Generally, EPA does not envision any cases where control of pollutants in discharge of wash 

waters that are generated cannot be accomplished.

(3) In its comments on the proposed C&D ELG/NSPS, NAHB expressed support for nonnumeric effluent limitations in the form of BMPs like this provision.

In its cover comment letter on the proposed C&D ELG/NSPS, NAHB stated that it “has 

consistently advocated for an ELG that allows for site-specific selection of BMPs, appropriate 

sediment basin sizing criteria and the implementation of pollution prevention practices.” NAHB 

comment cover letter at 2. NAHB stated that EPA’s proposed Option 1, a BMP-only ELG, 

“would build upon the significant environmental progress made to date by ensuring that all 

construction sites meet a minimum standard of excellence by adopting those erosion and 

sediment controls that have evolved and are now accepted across the country.” Id. NAHB 

urged EPA to broaden “best management practices and pollution prevention to ensure these 

practices can be implemented at every permitted construction site, in all circumstances across 

the country.” Id. at 3. 

In its detailed comments attached to its cover letter, NAHB continued to support a BMP-only 

ELG to control stormwater discharges from active construction sites. NAHB urged EPA “to 

remove any requirements to meet numeric effluent limits and proceed with a BMP-based ELG to 

control stormwater discharge.” NAHB detailed comments at 38. NAHB claimed that “[i]n the 

case of EPA's proposed C&D ELGs, the combination of ELG precedent and the fact that EPA is 

focusing exclusively on stormwater provides irrefutable support for a BMP-based ELG 

approach.” Id. at 42. NAHB concluded that “[t]here is substantial authority for and evidence 

regarding the success associated with permitting authorities relying on BMP-based approaches 

to achieve environmental objectives. EPA also should rely on a BMP-based approach for the 

C&D ELG rulemaking.” Id. at 46 (emphasis in original).
Supplemental Explanation in Support of BMPs in C&D ELG and NSPS February 15, 2012

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In addition, in its redline/strikeout “precisely crafted edits” of EPA’s proposed Option 1, the BMPonly ELG, NAHB suggested revisions to proposed 450.21(c)(5) to make that provision read as 

follows: “Minimize the discharge of pollutants resulting from the washing of equipment and 

vehicles using only water to remove sediment. If practicable, the site operator should consider 

diverting wash waters, such as water from wheel wash stations, to any on-site sediment basin 

or alternative controls that provide equivalent or better treatment”. EPA had proposed “Prohibit 

the discharge of pollutants resulting from the washing of equipment and vehicles using only 

water to remove sediment, unless wash waters, such as water from wheel wash stations, are 

treated in a sediment basin or alternative controls that provide equivalent or better treatment”.

Thus, while NAHB suggested changes to the provision, it did not suggest deleting the provision, 

thereby acknowledging, consistent with its overall comments in support of a BMP-only ELG, that

taking such measures as detailed, at a minimum, in this BMP provision as edited by NAHB, is 

key to controlling and minimizing the discharge of stormwater from active construction sites. 

See reference to “precisely crafted edits” on page 144 of NAHB’s detailed comments on the 

proposed ELG/NSPS, as well as the attachment to EPA-HQ-OW-2008-0465-1360. 

Moreover, commenters generally felt that a requirement to install wheel wash stations was 

infeasible. EPA agreed, and changed this requirement to mandate effective control of wash 

waters to minimize their discharge if they are generated. If permittees choose to do washing, or 

are required to do so by the permitting authority, then they would need to properly manage the 

water that is generated. EPA is not, however, mandating that washing be done through the 

ELG/NSPS.

(4) Implementation of this provision in NPDES permits.

The construction stormwater ELG will be implemented in NPDES permits as the applicable 

technology-based effluent limitations in those NPDES permits. The ELG is not directly 

applicable to any regulated entity. If the permitting authority chooses to copy the ELG verbatim 

into its draft proposed NPDES permit as the technology-based effluent limitation, dischargers 

will have an opportunity to provide comment on the need for more specificity if they are 

concerned that the narrative nature of the limit could unfairly subject them to arbitrary 

enforcement. Furthermore, in the event that the permitting authority does not provide any 

additional specificity, it is typical in stormwater permits for active construction for the permitting 

authorities to include a requirement to prepare a storm water pollution prevention plan (SWPPP)

in the permit. While the provisions of the SWPPP are not effluent limitations themselves, they 

indicate how the discharger intends to meet the narrative effluent limitations in the permit. As 

such, SWPPPs can be helpful to the regulated entity in demonstrating how they are meeting 

their effluent limitations. 

In the 2012 CGP, EPA has included a provision to implement this provision that requires that 

permittees provide an effective means of minimizing the discharge of pollutants from equipment 

and vehicle washing, wheel wash water, and other types of washing. Examples of effective 

controls include, but are not limited to, locating activities away from surface waters and 

stormwater inlets or conveyances and directing wash waters to a sediment basin or sediment 

trap, using filtration devices, such as filter bags or sand filters, or using other similarly effective 

controls. In addition, permittees must provide cover or a similarly effective means to prevent the 

discharge of pollutants from areas where soaps, detergents, or solvents will be stored. 

(5) Appropriate time for implementation of this BMP in the construction process.

Wash water needs to be managed as it is generated.