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

1 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 contr ol that provides equivalent or better treatment prior to discharge.

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(1) T his BMP control

s or minimiz

es 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 an d 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. T he 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 non

numeric effluent limitati ons 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 th at 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 li mits 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 stormwate r 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 enviro nmental 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

2 In addition, in its redline/strikeout “precisely crafted edits” of EPA’s proposed Option 1, the BMP

only ELG, NAHB suggest ed revision s 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 equipme nt 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 a s detailed, at a minimum, in this BMP provision as edited by NAHB, is key to control ling 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 , c ommenters 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 limitation s 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 e vent that the permitting authority does not provide any additional specificity, it is t ypical in stormwater permits for active construction for the p ermitting
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 limitati ons in the permit. As
such

, SWPPPs can be helpful to the regulated entity in demons trating how they are meeting
their effluent limitations.

In the 2012 CGP

, EPA has included a provision to implement this provision that requir es that permittees provide an effective means of minimizing the discharge of pollutants from equipment
and vehi cle 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 soa ps, detergents, or solvents will be stored.

( 5 ) A ppropriate time for implementation of this BMP in the construction process

.

Wash water needs to be managed as it is generated.