Effluent Limitations Guidelines and Standards for the Construction and Development Point Source Category

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 450

[EPA-HQ-OW-2008-0465; FRL-8744-1]

RIN 2040-AE91

Effluent Limitations Guidelines and Standards for the Construction and Development Point Source Category

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule.

SUMMARY:

The Environmental Protection Agency is proposing a regulation that would strengthen the existing regulatory program for discharges from construction sites by establishing technology-based Effluent Limitations Guidelines and New Source Performance Standards for the Construction and Development (C&D) point source category. This proposal, if implemented, would significantly reduce the amount of sediment and other pollutants discharged from construction sites. EPA estimates that this proposed rule would cost $1.9 billion dollars per year with annual monetized benefits of $332.9 million. This proposed rule requests comment and information on the proposed regulation and an alternate option with a different numeric limit based on different technologies, as well as specific aspects of the proposal such as technologies, costs, loading reductions, and economic achievability.

DATES:

Comments must be received on or before February 26, 2009.

ADDRESSES:

Submit your comments, identified by Docket ID No. EPA-HQ-OW-2008-0465, by one of the following methods:

•

http://www.regulations.gov:

This is EPA's preferred approach, although you may use the alternatives presented below. Follow the on-line instructions for submitting comments.

•

E-mail: OW-Docket@epa.gov.

•

Mail:

USEPA Docket Center, Environmental Protection Agency, Docket Number EPA-HQ-OW-2008-0465, Mailcode 2822T, 1200 Pennsylvania Ave., NW., Washington, DC 20460.

•

Hand Delivery:

USEPA Docket Center, Public Reading Room, 1301 Constitution Ave., NW., Room 3334, EPA West Building, Washington DC 20004. Such deliveries are only accepted during the Docket's normal hours of operation, and special arrangements should be made for deliveries of boxed information.

Instructions:

Direct your comments to Docket ID No. EPA-HQ-OW-2008-0465. EPA's policy is that all comments received will be included in the public docket without change and may be made available online at

http://www.regulations.gov,

including any personal information provided, unless the comment includes information claimed to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Do not submit information that you consider to be CBI or otherwise protected through

http://www.regulations.gov

or e-mail. The

http://www.regulations.gov

Web site is an “anonymous access” system, which means EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send an e-mail comment directly to EPA without going through

http://www.regulations.gov,

your e-mail address will be automatically captured and included as part of the comment that is placed in the public docket and made available on the Internet. If you submit an electronic comment, EPA recommends that you include your name and other contact information in the body of your comment and with any disk or CD-ROM you submit. If EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, EPA may not be able to consider your comment. Electronic files should avoid the use of special characters, any form of encryption, and be free of any defects or viruses. For additional information about EPA's public docket visit the EPA Docket Center homepage at

http://www.epa.gov/epahome/dockets.htm.

Docket:

All documents in the docket are listed in the

http://www.regulations.gov

index. Although listed in the index, some information is not publicly available, e.g., CBI or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, will be publicly available only in hard copy. Publicly available docket materials are available either electronically in

http://www.regulations.gov

or in hard copy at the USEPA Docket Center, Public Reading Room, Room 3334, EPA West Building, 1301 Constitution Ave., NW., Washington DC. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The telephone number for the Public Reading Room is (202) 566-1744, and the telephone number for the EPA Docket Center is (202) 566-2426. Please note that several of the support documents are available at no charge on EPA's Web site; see Supporting Documentation below.

FOR FURTHER INFORMATION CONTACT:

For technical information concerning today's proposed rule, contact Mr. Jesse W. Pritts at 202-566-1038 (

pritts.jesse@epa.gov

). For economic information contact Mr. Todd Doley at 202-566-1160 (

doley.todd@epa.gov

).

SUPPLEMENTARY INFORMATION:

Regulated Entities

Entities potentially regulated by this action include:

Category

Examples of regulated entities

North American Industry Classification System (NAICS) code

Industry

Construction activities required to obtain NPDES permit coverage and performing the following activities:

Construction of buildings, including building, developing and general contracting

236

Heavy and civil engineering construction, including land subdivision

237

EPA does not intend the preceding table to be exhaustive, but provides it as a guide for readers regarding entities likely to be regulated by this action. This table lists the types of entities that EPA is now aware could potentially be regulated by this action. Other types of entities not listed in the table could also be regulated. To determine whether your facility is regulated by this action, you should carefully examine the applicability criteria in § 450.10 of today's proposed rule and the definition of “construction activity” and “small construction activity” in existing EPA regulations at 40 CFR 122.26(b)(14)(x) and 122.26(b)(15), respectively. If you have questions regarding the

applicability of this action to a particular entity, consult one of the persons listed for technical information in the preceding

FOR FURTHER INFORMATION CONTACT

section.

Supporting Documentation

Several key documents support the proposed regulation:

1. “Development Document for Proposed Effluent Guidelines and Standards for the Construction and Development Category,” EPA-821-R-08-007. (“Development Document”) This document presents EPA's methodology and technical conclusions concerning the C&D category.

2. “Economic Analysis for Proposed Effluent Guidelines and Standards for the Construction and Development Category,” EPA-821-R-08-008. (“Economic Analysis”) This document presents the methodology employed to assess economic impacts of the proposed rule and the results of the analysis.

3. “Environmental Impact and Benefits Assessment for Proposed Effluent Guidelines and Standards for the Construction and Development Category,” EPA-821-R-08-009 (“Environmental Assessment”). This document presents the methodology to assess environmental impacts and benefits of the proposed rule and the results of the analysis.

Major supporting documents are available in hard copy from the National Service Center for Environmental Publications (NSCEP), U.S. EPA/NSCEP, P.O. Box 42419, Cincinnati, Ohio, USA 45242-2419, telephone 800-490-9198,

http://www.epa.gov/ncepihom/.

You can obtain electronic copies of this preamble and proposed rule as well as the technical and economic support documents for today's proposal at EPA's Web site for the C&D rule,

http://www.epa.gov/waterscience/guide/construction.

Overview

This preamble describes the terms, acronyms, and abbreviations used in this document; the background documents that support these proposed regulations; the legal authority of this proposed rule; a summary of the proposal; background information; and the technical and economic methodologies used by the Agency to develop this proposed regulation. While EPA solicits comments on this entire proposal, EPA emphasizes specific areas of interest where we would particularly like comments, information and data.

Table of Contents

I. Legal Authority

II. Purpose & Summary of the Proposed Rule

III. Background on Existing Regulatory Program

A. Clean Water Act

B. NPDES Stormwater Permit Program

C. Other State and Local Stormwater Requirements

D. Technology-Based Effluent Limitations Guidelines and Standards

IV. Scope of the Proposal

V. Overview of the Construction and Development Industry and Construction Activities

VI. Summary of Data Collection Activities

A. State Data

B. National Land Cover Dataset (NLCD)

C. Enhanced River Reach File 1.2 (ERF1)

D. NPDES Notice of Intent (NOI) Data

E. Soils Data

F. NOAA Rainfall Data

G. Parameter Elevation Regressions on Independent Slopes Model (PRISM)

H. Revised Universal Soil Loss Equation (RUSLE) R Factors

I. Economic Data

VII. Characteristics of Discharges From Construction Activity

VIII. Description of Available Technologies

A. Introduction

B. Erosion Control Measures

C. Sediment Control Measures

D. Other Construction and Development Site Management Practices

IX. Development of Effluent Limitations Guidelines and Standards

A. Description of the Regulatory Options Considered

B. Effluent Limitations Included in All Regulatory Options

C. Options for BPT, BCT, BAT and NSPS

D. Option Selection Rationale for BPT

E. Option Selection Rationale for BAT and NSPS

F. Option Selection Rationale for BCT

X. Methodology for Estimating Costs to the Construction and Development Industry

XI. Economic Impact and Social Cost Analysis

A. Introduction

B. Description of Economic Activity

C. Method for Estimating Economic Impacts

D. Results

XII. Cost-Effectiveness Analysis

XIII. Non Water-Quality Environmental Impacts

A. Air Pollution

B. Solid Waste Generation

C. Energy Usage

XIV. Environmental Assessment

A. Introduction

B. Methodology for Estimating Environmental Impacts and Pollutant Reductions

XV. Benefit Analysis

A. Benefits Categories Estimated

B. Quantification of Benefits

XVI. Monetized Benefit-Cost Comparison

XVII. Approach to Determining Long-Term Averages, Variability Factors, and Effluent Limitations and Standards

A. Definitions

B. Data Selection

C. Statistical Percentile Basis for Limitations

D. Daily Maximum Limitations

E. Engineering Review of Limitations

F. Monthly Average Limitations

XVIII. Regulatory Implementation

A. Relationship of Effluent Guidelines to NPDES Permits and ELG Compliance Dates

B. Upset and Bypass Provisions

C. Variances and Waivers

D. Other Clean Water Act Requirements

XIX. Related Acts of Congress, Executive Orders, and Agency Initiatives

A. Executive Order 12866: Regulatory Planning and Review

B. Paperwork Reduction Act

C. Regulatory Flexibility Act

D. Unfunded Mandates Reform Act (UMRA)

E. Executive Order 13132: Federalism

F. Executive Order 13175 (Consultation and Coordination With Indian Tribal Governments)

G. Executive Order 13045: Protection of Children from Environmental Health Risks and Safety Risks

H. Executive Order 13211 (Energy Effects)

I. National Technology Transfer and Advancement Act

J. Executive Order 12898: Federal Actions To Address Environmental Justice in Minority Populations and Low-Income Populations.

XX. Solicitation of Data and Comments

A. General Solicitation of Comment

B. Specific Solicitation of Comments and Data

C. Guidelines for Submission of Analytical Data

I. Legal Authority

EPA is proposing this regulation under the authorities of sections 301, 304, 306, 308, 402, 501 and 510 of the Clean Water Act (CWA), 33 U.S.C. 1311, 1314, 1316, 1318, 1342, 1361 and 1370 and pursuant to the Pollution Prevention Act of 1990, 42 U.S.C. 13101

et seq.

II. Purpose & Summary of the Proposed Rule

Despite substantial improvements in the nation's water quality since the inception of the Clean Water Act, 45 percent of assessed river and stream miles, 47 percent of assessed lake acres, and 32 percent of assessed square miles of estuaries show impairments from a wide range of sources. Improper control of stormwater discharges from construction activity is among the many contributors of sediment which is one of the major remaining water quality problems throughout the United States. Sediment is the leading cause of water quality impairment for streams and rivers. It is also one of the leading causes of lake and reservoir water quality impairment and wetland degradation. Turbidity and suspended solids are also major sources of water quality impairment nationwide. Turbidity or suspended solids impair 695,133 miles of streams nationwide. In

addition, 376,832 acres of lakes and reservoirs have been documented as impaired by turbidity or suspended solids nationwide. The sediment and turbidity entrained in stormwater discharges from construction activity contributes to harm in aquatic ecosystems, increases drinking water treatment costs, and contributes to impairment to recreational uses of impacted waters. Sediment can also accumulate in rivers, lakes, and reservoirs, leading to the need for dredging or other mitigation.

Construction activity typically involves site selection and planning, and land-disturbing tasks such as clearing, excavating and grading. Disturbed soil, if not managed properly, can be easily washed off-site during storm events. Stormwater discharges generated during construction activities can cause an array of physical, chemical and biological impacts. Sediment discharges can cause an array of physical and biological impacts on receiving waters. In addition to sediment, a number of other pollutants (e.g., metals and nutrients) are preferentially absorbed or adsorbed onto mineral or organic particles found in fine sediment. These pollutants can cause an array of chemical and biological water quality impairments. The interconnected processes of erosion (i.e., detachment of soil particles by water), sediment transport, and delivery to receiving waters are the primary pathways for the addition of pollutants from construction and development (C&D) sites into aquatic systems.

A primary concern at most C&D sites is the erosion and transport process related to fine sediment because rain splash, rills (small channels typically less than one foot deep) and sheetwash (thin sheets of water flowing across a surface) encourage the detachment and transport of sediment to water bodies. Although streams and rivers naturally carry sediment loads, discharges from construction activity can elevate these loads to levels above those in undisturbed watersheds.

Existing national stormwater regulations at 40 CFR 122.26 require permittees to implement control measures to manage discharges associated with construction activity. Today's proposal would establish a technology-based “floor” or minimum requirements on a national basis. This rule would constitute the nationally applicable, technology-based effluent limitations guidelines (ELGs) and new source performance standards (NSPS) (referred to collectively in this notice as “ELGs” or “effluent limitations guidelines,” unless specifically referencing NSPS), applicable to all dischargers currently required to obtain a National Pollutant Discharge Elimination System (NPDES) permit pursuant to 40 CFR 122.26(b)(14)(x) and 122.26(b)(15). The proposed ELGs would require stormwater discharges from certain C&D sites to meet effluent limitations designed to reduce the amount of sediment, turbidity, Total Suspended Solids (TSS) and other pollutants in stormwater discharges from the site. EPA acknowledges that many state and local governments have existing effluent limitations and standards for controlling stormwater and wastewater discharges from construction sites. Today's proposed ELGs are intended to work in concert with these existing state and local programs. Today's proposed regulation would establish a numeric effluent limit for turbidity in discharges from some C&D sites. EPA envisions these turbidity effluent limits as requiring an additional layer of management practices and/or treatment above what most state and local programs are currently requiring. Permitting authorities would be required to incorporate these turbidity limitations into their permits and permittees would be required to implement control measures to meet a numeric turbidity limit in discharges of stormwater from their C&D sites. EPA is not dictating that a specific technology be used to meet the numeric limit, but is specifying the maximum turbidity level that can be present in discharges from C&D sites. However, EPA's proposed limits are based on its assessment of what specific technologies can reliably achieve. Permittees would have the flexibility to select management practices that are best suited to site-specific conditions present on each individual C&D site if they are able to consistently meet the limits.

III. Background on Existing Regulatory Program

A. Clean Water Act

Congress passed the Federal Water Pollution Control Act of 1972 (Pub. L. 92-500, October 18, 1972) (hereinafter the Clean Water Act or CWA), 33 U.S.C. 1251

et seq.

, with the stated objectives to “restore and maintain the chemical, physical, and biological integrity of the Nation's waters.” Section 101(a), 33 U.S.C. 1251(a). To achieve this goal, the CWA provides that “the discharge of any pollutant by any person shall be unlawful” except in compliance with other provisions of the statute. CWA section 301(a). U.S.C. 1311. The CWA defines “discharge of a pollutant” broadly to include “any addition of any pollutant to navigable waters from any point source.” CWA section 502(12). 33 U.S.C. 1362(12). EPA is authorized under CWA section 402(a) to issue a National Pollutant Discharge Elimination System (NPDES) permit for the discharge of any pollutant from a point source notwithstanding Section 301(a). These NPDES permits are issued by EPA regional offices or NPDES authorized state or tribal agencies. Since 1972, EPA and the states have issued NPDES permits to thousands of dischargers, both industrial (e.g., manufacturing, energy and mining facilities) and municipal (e.g., sewage treatment plants). As required under Title III of the CWA, EPA has promulgated ELGs and standards for many industrial point source categories, and these requirements are incorporated into the permits.

The Water Quality Act of 1987 (Pub. L. 100-4, February 4, 1987) amended the CWA, adding CWA section 402(p) to require implementation of a comprehensive program for addressing stormwater discharges. 33 U.S.C. 1342(p). The NPDES program was expanded by requiring EPA or NPDES authorized states or tribes to issue NPDES permits for stormwater discharges listed under Section 402(p)(2), which include municipal and industrial stormwater discharges. Industrial stormwater dischargers, municipal separate storm sewer systems and other stormwater dischargers designated by EPA must obtain NPDES permits pursuant to CWA section 402(p). Stormwater discharges associated with industrial activity must meet all applicable provisions of CWA sections 301 and 402, including meeting technology-based effluent limitations.

B. NPDES Stormwater Permit Program

EPA's Phase I stormwater regulations promulgated in 1990 identified stormwater discharges associated with construction activity as one of several types of industrial activity requiring an NPDES permit. Dischargers must apply for and obtain authorization to discharge (or “permit coverage”) (40 CFR 122.26(b)(14)(x) and (c)(1)). As described in the Phase I regulations, a permit is required for discharges associated with construction activity, including clearing, grading, and excavation, if the construction activity:

• Will disturb five acres or greater; or

• Will disturb less than five acres but is part of a larger common plan of development or sale whose total land disturbing activities total five acres or greater.

EPA defines these “large” construction sites as one of the eleven categories of stormwater dischargers associated with industrial activity. (See 40 CFR 122.26(b)(14)).

The Phase II stormwater regulations, promulgated in 1999, extended permit coverage to construction activity that results in land disturbance of one acre or greater (40 CFR 122.26(b)(15)), including sites less than one acre that are part of a larger common plan of development or sale whose total land disturbing activities total more than an acre. EPA's NPDES regulations define these sites,

i.e.

, sites disturbing between one and five acres, as “small” construction sites.

In addition to requiring permits for discharges associated with construction activity, the NPDES regulations require permits for certain municipal separate storm sewer systems (MS4s). Operators of these MS4s, typically local governments, must develop and implement a stormwater management program, including a requirement to address stormwater discharges from construction activity. More details on the requirements of MS4 programs are described in section III.B.2.

1. Stormwater Permits for Construction Activity

The NPDES regulations provide two options for obtaining authorization to discharge or “permit coverage”: General permits and individual permits. A brief description of these types of permits as they apply to construction sites follows.

a. General NPDES Permits

The vast majority of discharges from construction activity are covered under NPDES general permits. EPA, states and tribes use general permits to cover a group of similar dischargers under one permit. See 40 CFR 122.28. General permits simplify the process for dischargers to obtain authorization to discharge, provide permit requirements for any discharger that files a notice of intent to be covered, and reduce the administrative workload for NPDES permitting authorities. General permits, including a fact sheet describing the rationale for permit conditions, are issued by NPDES permitting authorities through public notice. Typically, to obtain authorization to discharge under a construction general permit, a discharger (typically, a developer, builder, or contractor) submits to the permitting authority a Notice of Intent (NOI) to be covered under the general permit. By submitting the NOI, the discharger acknowledges that it is eligible for coverage under the general permit and agrees to the conditions in the published general permit. Discharges from the construction activity are authorized consistent with the terms and conditions established in the general permit.

EPA regulations allow NPDES permitting authorities to regulate discharges from small C&D sites under a general permit without the discharger submitting an NOI if the permitting authority determines an NOI is inappropriate and the general permit includes language acknowledging that an NOI is unnecessary (40 CFR 122.28(b)(2)(v)). To implement such a requirement, the permitting authority must specify in the public notice of the general permit any reasons why an NOI is not required. In these instances, any stormwater discharges associated with small construction activity are automatically covered under an applicable general permit and the discharger is required to comply with the terms, conditions and effluent limitations of such permit.

Similarly, EPA, states and tribes have the authority to notify a C&D site operator that it is covered by a general permit, even if that operator has not submitted an NOI (40 CFR 122.28(b)(2)(vi)). In these instances, the operator is given the opportunity to request coverage under an individual permit. Individual permits are discussed in section III.B.1.d.

b. EPA Construction General Permit

Since 1992, EPA has issued a series of “national” Construction General Permits (CGP) that cover areas where EPA is the NPDES permitting authority. At present, EPA is the permitting authority in five states (Alaska, Idaho, Massachusetts, New Hampshire, and New Mexico), the District of Columbia, Puerto Rico, all other U.S. territories with the exception of the Virgin Islands, federal facilities in four states (Colorado, Delaware, Vermont, and Washington), most Indian lands and a couple of other specifically designated activities in specific states (e.g., oil and gas activities in Texas and Oklahoma). EPA issued a final “national” CGP on July 1, 2003 (63 FR 7898), modified on November 22, 2004 (changes effective January 21, 2005). EPA's current CGP became effective on June 30, 2008 (see 74 FR 40338). Following promulgation of the effluent limitations guidelines, EPA will issue a revised CGP incorporating the new ELGs.

The key component of EPA's CGP is the requirement to minimize discharges of pollutants in stormwater discharges using control measures that reflect best engineering practices. Dischargers must minimize their discharge of pollutants in stormwater using appropriate erosion and sediment control “best management practices” (BMPs) and control measures for other pollutants such as litter, construction debris, and construction chemicals that could be exposed to stormwater and other wastewater. The 2008 CGP requires dischargers to develop and implement a stormwater pollution prevention plan (SWPPP) to document the steps they will take to comply with the terms, conditions and effluent limitations of the permit. EPA's guidance manual, “Developing Your Stormwater Pollution Prevention Plan: A Guide for Construction Sites,” (EPA 833/R-060-04, May 2007; available on EPA's Web site at

http://www.epa.gov/npdes/stormwater

) describes the SWPPP process in detail. As detailed in EPA's CGP, the SWPPP must include a description of the C&D site with maps showing drainage patterns, discharge points, and locations of runoff controls; a description of the control measures used; and inspection procedures. A copy of the SWPPP must be kept on the construction site from the date of project initiation to the date of final stabilization. The CGP does not require permittees to submit a SWPPP to the permitting authority; however a copy must be readily available to authorized inspectors during normal business hours.

Other requirements in the CGP include conducting regular inspections and reporting releases of reportable quantities of hazardous substances.

To discontinue permit coverage, a discharger must either complete final stabilization of the site, transfer responsibility to another party (e.g., a developer transferring land to a home builder), or for a residential property, complete temporary stabilization and transfer the property to the homeowner. The permittee submits a Notice of Termination (NOT) Form to the permitting authority upon satisfying the appropriate permit termination conditions described in the CGP.

c. State Construction General Permits

Whether EPA, a state or a tribe issues the general permit, the CWA requires that NPDES permits must include technology-based effluent limitations. In addition, where technology-based effluent limitations are insufficient for the discharge to meet applicable water quality standards, the permit must contain water quality-based effluent limitations as necessary to meet those standards. See sections 301, 304, 303, 306, and 402 of the CWA. PUD No. 1 of

Jefferson County

v.

Washington Department of Ecology

, 511 U.S. 700, 704-705 (1994).

For the most part, state-issued general permits for stormwater discharges from construction activity have followed EPA's CGP format and content, starting with EPA's first CGP issued in 1992 (57 FR 41176; September 9, 1992). Over time, some states have changed components of their permits to better address the specific conditions encountered at construction sites within their jurisdiction (e.g., soil types, topographic or climatic characteristics, or other relevant factors). For example, Washington, Oregon and Vermont's CGPs include turbidity action levels and discharge monitoring requirements for C&D sites applicable to all or a subset of construction sites.

d. Individual NPDES Permits

A permitting authority may require any C&D site to apply for an individual permit rather than using the general permit. Likewise, any discharger may request to be covered under an individual permit rather than seek coverage under an otherwise applicable general permit (40 CFR 122.28(b)(3)). Unlike a general permit, an individual permit is intended to be issued to one permittee, or a few co-permittees. Individual permits for stormwater discharges from construction sites are rarely used, but when done so, are most often used for very large projects or projects located in sensitive watersheds. EPA estimates that fewer than one half of one percent (< 0.5%) of all construction sites are covered under individual permits.

2. Municipal Stormwater Permits and Local Government Regulation of Stormwater Discharges Associated With Construction Activity

Many local governments, as MS4 permittees, have a role to play in the regulation of construction activities. This section provides an overview of MS4 responsibilities associated with controlling stormwater discharges from construction activity.

a. NPDES Requirements

A municipal separate storm sewer system (MS4) is a conveyance or system of conveyances designed or used for collecting or conveying stormwater. These systems are not combined sewers and not part of a Publicly Owned Treatment Works (POTW). See 40 CFR 122.26(b)(8). A municipal separate storm sewer system (MS4) is all large, medium, and small municipal storm sewers or those designated as such under the regulations. See 40 CFR 122.26(b)) (18). The NPDES stormwater regulations require many MS4s to apply for permits. In general, the 1990 Phase I rule requires MS4s serving populations of 100,000 or more to obtain coverage under an MS4 individual permit. See 40 CFR 122.26(a)(3). The 1999 Phase II rule requires most small MS4s located in urbanized areas also to obtain coverage. See 40 CFR 122.33. The Phase II regulations also provide permitting authorities with the authority to designate any additional MS4s located outside of urbanized areas for permit coverage where the permitting authority determines that storm water controls are needed for the discharge based on wasteload allocations that are part of total maximum daily loads that address pollutants of concern or the permitting authority or the EPA Regional Administrator determines that the discharge, or category of discharges within a geographic area, contributes to a violation of a water quality standard or is a significant contributor of pollutants to waters of the United States. 40 CFR 122.26(9)(i)(C) and (D). Regardless of the type of permit, MS4s are required to develop stormwater management programs that detail the procedures they will use to control discharges of pollutants in stormwater from the MS4.

Both the Phase I and II rules require regulated municipalities to develop comprehensive stormwater management programs which include, among other elements, the regulation of discharges from construction sites. The Phase I regulations require medium and large MS4s to implement and maintain a program to reduce pollutants in stormwater runoff from construction sites, including procedures for site planning, requirements for structural and non-structural BMPs, procedures for identifying priorities for inspecting sites and enforcing control measures, and development and dissemination of appropriate educational and training materials. In general, the Phase II regulations require small MS4s to develop, implement, and enforce a program to control pollutants in stormwater runoff from construction activities which includes developing an ordinance to require implementation of erosion and sediment control practices, to control waste and to have procedures for site plan review and site inspections. Thus, as described above, both the Phase I and Phase II regulations specifically anticipate a local program for regulating stormwater discharges from construction activity. See 40 CFR 122.26(d)(2)(iv)(D) for Phase I MS4s and 40 CFR 122.34(b)(4) for Phase II MS4s. EPA has provided many guidance materials to the NPDES permitting authorities and MS4s that recommend components and activities for a well-operated local stormwater management program.

EPA promulgated two provisions intended to minimize potential duplication of requirements or inconsistencies between requirements. First, 40 CFR 122.35 provides that a small MS4 is allowed to rely on another entity to satisfy its NPDES permit obligations, including construction site control, provided the other entity implements a program that is at least as stringent as the corresponding NPDES permit requirements and the other entity agrees to implement the control measures on the small MS4's behalf. Thus, for example, where a county implements a construction site stormwater control program already, and that program is at least as stringent as the controls required by a small MS4's NPDES permit, the MS4 may reference that program in the Notice of Intent to be covered by a general permit, or in its permit application, rather than developing and implementing a new program to require control of construction site stormwater within its jurisdiction.

Similarly, EPA or the state permitting authority may substitute certain aspects of the requirements of the EPA or state permit by incorporating by reference the requirements of a “qualifying local program” in the EPA or state CGP. A “qualifying local program” is an existing sediment and erosion control program that meets the minimum requirements as established in 40 CFR 122.44(s). By incorporating a qualifying local, state or tribal program into the EPA or state CGP, construction sites covered by the qualifying program in that jurisdiction would simply follow the incorporated local requirements in order to meet the corresponding requirements of the EPA or state CGP.

b. EPA Guidance to Municipalities

EPA developed several guidance documents for municipalities to implement the NPDES Phase II rule.

• National Menu of BMPs (

http://www.epa.gov/npdes/menuofbmps/menu.htm

). This document provides guidance to regulated MS4s as to the types of practices they could use to develop and implement their stormwater management programs. The menu includes descriptions of practices that local programs can implement to reduce impacts of stormwater discharges from construction activities.

• Measurable Goals Guidance for Phase II MS4s (

http://www.epa.gov/npdes/stormwater/measurablegoals

). This document assists small MS4s in defining performance targets and

includes examples of goals for practices to control stormwater discharges from construction activities.

• Storm Water Phase II Compliance Assistance Guide (EPA 833-R-00-002, March 2000,

http://cfpub.epa.gov/npdes/stormwater/smms4.cfm?program_id=6

). The guide provides an overview of compliance responsibilities for MS4s, small construction sites, and certain other industrial stormwater discharges affected by the Phase II rule.

• Fact Sheets on various stormwater control technologies, including hydrodynamic separators (EPA 832-F-99-017), infiltrative practices (EPA 832-F-99-018 and EPA 832-F-99-019), modular treatment systems (EPA 832-F-99-044), porous pavement (EPA 832-F-99-023), sand filters (EPA 832-F-99-007), turf reinforcement mats (EPA 832-F-99-002), vegetative covers (EPA 832-F-99-027), swales (EPA 832-F-99-006) and wet detention ponds (EPA 832-F-99-048). (Available at

http://www.epa.gov/npdes/stormwater/

; click on “Publications.”)

C. Other State and Local Stormwater Requirements

States and municipalities may have other requirements for flood control, erosion and sediment control, and in many cases, stormwater management. Many of these provisions were enacted before the promulgation of the EPA Phase I stormwater rule although many have been updated since. An EPA analysis found that all states have laws for erosion and sediment control measures, with these laws implemented by state, county, or local governments. A summary of existing state requirements is provided in the Development Document.

D. Technology-Based Effluent Limitations Guidelines and Standards

Effluent limitation guidelines and new source performance standards are technology-based effluent limitations required by CWA sections 301 and 306 for categories or subcategories of point source dischargers. These limitations, which can be either numeric or non-numeric, along with water quality-based effluent limitations, if necessary, are incorporated into NPDES permits. ELGs and NSPS are based on the degree of control that can be achieved using various levels of pollutant control technology, as defined in Title III of the CWA and outlined below.

1. Best Practicable Control Technology Currently Available (BPT)

In establishing effluent guidelines for a point source category, the CWA requires EPA to specify BPT effluent limits for conventional, toxic, and nonconventional pollutants. In doing so, EPA is required to determine what level of control is technologically available and economically practicable. CWA section 301(b)(1)(A). In specifying BPT, the CWA requires EPA to look at a number of factors. EPA considers the cost of achieving effluent reductions in relation to the effluent reduction benefits. The Agency also considers the age of the equipment and facilities, the processes employed and any required process changes, engineering aspects of the control technologies, non-water quality environmental impacts (including energy requirements), and such other factors as the Administrator deems appropriate. CWA section 304(b)(1)(B). Traditionally, EPA establishes BPT effluent limitations based on the average of the best performance of facilities within the category of various ages, sizes, processes or other common characteristics. Where existing performance is uniformly inadequate, EPA may require higher levels of control than currently in place in a category if the Agency determines that the technology can be practicably applied. See e.g.,

American Frozen Foods Inst.

v.

Train

, 539 F.2d 107, 117 (D.C. Cir. 1976).

EPA assesses cost-reasonableness of BPT limitations by considering the cost of treatment technologies in relation to the effluent reduction benefits achieved. This inquiry does not limit EPA's broad discretion to adopt BPT limitations that are achievable with available technology unless the required additional reductions are “wholly out of proportion to the costs of achieving such marginal level of reduction.” Moreover, the inquiry does not require the Agency to quantify benefits in monetary terms. See, e.g.,

American Iron and Steel Institute

v.

EPA

, 526 F. 2d 1027, 1051 (3rd Cir. 1975).

In balancing costs against the effluent reduction, EPA considers the volume and nature of expected discharges after application of BPT, the general environmental effects of pollutants, and the cost and economic impacts of the required level of pollution control. In past effluent limitation guidelines, BPT cost-reasonableness comparisons ranged from $0.26 to $41.44 per pound removed in year 2008 dollars. This range is not inclusive of all categories regulated by BPT, but nonetheless represents a very broad range of cost-reasonableness values. About half of the cost-reasonableness values represented by this range are less than $2.50 per pound (in 2001 dollars). In developing guidelines, the Act does not require consideration of water quality problems attributable to particular point sources, nor does it require consideration of water quality improvements in particular bodies of water. See

American Frozen Foods Inst.

v.

Train

, 539 F.2d 107, 117 (D.C. Cir. 1976);

Weyerhaeuser Company

v.

Costle

, 590 F. 2d 1011, 1036, 1041-44 (D.C. Cir. 1978).

2. Best Available Technology Economically Achievable (BAT)

BAT effluent guidelines are applicable to toxic (priority) and nonconventional pollutants. EPA has identified 65 pollutants and classes of pollutants as toxic pollutants, of which 126 specific substances have been designated priority toxic pollutants. 40 CFR 401.15 and 40 CFR part 423, Appendix A. In general, BAT represents the best available performance of direct discharging facilities in the subcategory or category. CWA section 304(b)(2)(A). The factors considered in assessing BAT include the cost of achieving BAT effluent reductions, the age of equipment and facilities involved, the processes employed, engineering aspects of the control technology, potential process changes, non-water quality environmental impacts (including energy requirements), and such factors as the Administrator deems appropriate. CWA section 304(b)(2). The Agency retains considerable discretion in assigning the weight to be accorded to these factors.

Natural Resources Defense Council

v.

EPA

, 863 F.2d 1420, 1426 (9th Cir. 1988). An additional statutory factor considered in setting BAT is “economic achievability.” EPA may determine the economic achievability of an option on the basis of the total cost to the subcategory and the overall effect of the rule on the industry's financial health. The Agency may base BAT limitations upon effluent reductions attainable through changes in a facility's processes and operations. See

Texas Oil & Gas Ass'n

v.

EPA

, 161 F.3d 923, 928 (5th Cir. 1998) (citing “process changes” as one factor EPA must consider in determining BAT); see also,

American Meat Institute

v.

EPA

, 526 F.2d 442, 464 (7th Cir. 1975). As with BPT, where existing performance is uniformly inadequate, EPA may base BAT upon technology transferred from a different subcategory or from another category. See

CPC International Inc.

v.

Train

, 515 F.2d 1032, 1048 (8th Cir. 1975) (established criteria EPA must consider in determining whether technology from one industry can be applied to another); see also,

Tanners' Council of America, Inc.

v.

Train

, 540 F.2d 1188 (4th Cir. 1976). In addition,

the Agency may base BAT upon manufacturing process changes or internal controls, even when these technologies are not common industry practice. See

American Frozen Foods Inst.

v.

Train

, 539 F.2d 107, 132 (D.C. Cir. 1976).

3. Best Conventional Pollutant Control Technology (BCT)

The 1977 amendments to the CWA required EPA to identify effluent reduction levels for conventional pollutants associated with BCT technology for discharges from existing point sources. BCT is not an additional limitation, but replaces Best Available Technology (BAT) for control of conventional pollutants. In addition to other factors specified in CWA section 304(b)(4)(B), the Act requires that EPA establish BCT limitations after consideration of a two-part “cost-reasonableness” test. EPA explained its methodology for the development of BCT limitations in July 1986 (51 FR 24974).

Section 304(a)(4) designates the following as conventional pollutants: Biochemical oxygen demand (BOD

5

), total suspended solids (TSS), fecal coliform, pH, and any additional pollutants defined by the Administrator as conventional. 40 CFR 401.16. The Administrator designated oil and grease as an additional conventional pollutant on July 30, 1979 (44 FR 44501).

4. New Source Performance Standards (NSPS)

NSPS reflect effluent reductions that are achievable based on the best available demonstrated control technology. New sources, as defined in CWA section 306, have the opportunity to install the best and most efficient production processes and wastewater treatment technologies. As a result, NSPS should represent the greatest degree of effluent reduction attainable through the application of the best available demonstrated control technology for all pollutants (i.e., conventional, nonconventional, and priority pollutants). In establishing NSPS, CWA section 306 directs EPA to take into consideration the cost of achieving the effluent reduction and any non-water quality environmental impacts and energy requirements.

5. Pretreatment Standards

The CWA also defines standards for indirect discharges, i.e., discharges into publicly owned treatment works (POTWs). These standards are known as Pretreatment Standards for Existing Sources (PSES) and Pretreatment Standards for New Sources (PSNS), and are promulgated under CWA section 307(b). EPA has no data indicating that construction sites typically discharge directly to POTWs. Therefore, EPA is not proposing PSES or PSNS for the C&D category. EPA determined that the majority of construction sites discharge either directly to waters of the U.S. or through MS4s. In some urban areas, construction sites may discharge to combined sewer systems (i.e., sewers carrying both stormwater and domestic sewage through a single pipe) which lead to POTWs. Sediment and turbidity, which are the primary pollutants associated with construction site discharges, are susceptible to treatment in POTWs, using technologies commonly employed such as primary clarification. EPA has no evidence that construction site discharges to POTWs would cause interference, pollutant pass-through or sludge contamination.

6. EPA Authority to Promulgate Non-Numeric Effluent Limitations

The regulatory options proposed today include non-numeric effluent limitations that will control the discharge of pollutants from C&D sites. It is well established that EPA has the authority to promulgate non-numeric effluent limitations in addition to or in lieu of numeric limits. The CWA does not mandate the use of numeric limitations only and EPA's position finds support in the language of the CWA. The definition of “effluent limitation” means “any restriction * * * on quantities, rates, and concentrations of chemical, physical, biological, and other constituents * * *” CWA section 502(11).

Federal courts have recognized the CWA does not mandate that EPA use numeric effluent limitations. In

Citizens Coal Council

v.

U.S. EPA

, 447 F3d 879, 895-96 (6th Cir. 2006), the Sixth Circuit, in upholding EPA's use of non-numeric effluent limitations, agreed with EPA that it derives authority under CWA sections 402(a), 304(b) and 502(11) to incorporate non-numeric effluent limitations for conventional and non-conventional pollutants. The Sixth Circuit further held as reasonable the Agency position that CWA sections 304(b), 304(e) and 502(11), read together, allow non-numeric effluent limitations to supplement CWA section 304(b), or can stand as effluent limitations themselves. See also,

Waterkeeper Alliance, Inc.

v.

U.S. EPA

, 399 F.3d 486, 496-97, 502 (2d Cir. 2005) (EPA use of non-numerical effluent limitations in the form of best management practices are effluent limitations under the CWA);

Natural Res. Def. Council, Inc.

v.

EPA

, 673 F.2d 400, 403 (D.C. Cir. 1982) (“section 502(11) [of the CWA] defines 'effluent limitation' as 'any restriction' on the amounts of pollutants discharged, not just a numerical restriction.”);

Natural Res. Def. Council, Inc.

v.

Costle

, 568 F.2d 1369 (D.C. Cir. 1977) (in determining EPA did not have the authority to exclude a particular point source from the NPDES program, the Court held “when numerical effluent limitations are infeasible, EPA may issue permits with conditions designed to reduce the level of effluent discharges to acceptable levels. This may well mean opting for a gross reduction in pollutant discharge rather than fine-tuning suggested by numerical limitations.”)

EPA's NPDES regulations reflect EPA's long standing interpretation, as supported by federal court decisions, that the CWA allows for non-numeric effluent limitations. 40 CFR 122.44(k).

7. 2002 Construction and Development Proposal and Subsequent Litigation

EPA identified the C&D industry in its CWA section 304(m) plan in 2000 as an industrial point source category for which EPA intended to conduct rulemaking. 65 FR at 53,008 and 53,011 (August 31, 2000). On June 24, 2002, EPA published a proposed rule that contained several options for the control of stormwater discharges from construction sites, including ELGs and NSPS. (67 FR 42644; June 24, 2002).

On April 26, 2004, EPA determined that national effluent limitations guidelines would not be the most effective way to control discharges from construction sites, and instead chose to rely on the range of existing programs, regulations, and initiatives that already existed at the federal, state and local level. (69 FR 22472; April 26, 2004).

On October 6, 2004, the Natural Resources Defense Council, Inc. and additional plaintiffs filed a complaint in district court alleging that EPA's decision not to promulgate ELGs and NSPSs for the C&D industry violated a mandatory duty under the CWA. The district court, in

NRDC

v.

EPA

, 437 F.Supp.2d 1137, 1139 (C.D. Cal. 2006), held that CWA section 304(m) imposes on EPA a mandatory duty to promulgate ELGs and NSPSs for new industrial point source categories named in a CWA section 304(m) plan. The district court enjoined EPA to propose ELGs and NSPSs for the C&D industry by December 1, 2008 and to promulgate ELGs and NSPSs as soon as practicable, but in no event later than December 1, 2009. On appeal, the

Ninth Circuit in NRDC

v.

EPA

, 2008 WL 4253944 (9th Cir. 2008) affirmed the district court's

decision holding that “* * * the CWA is unambiguous that the EPA must promulgate ELGs and NSPSs for the point-source categories listed in a plan pursuant to [section] 304(m) * * *” The deadline to seek re-hearing in the Ninth Circuit was November 3, 2008. The Agency requested a 30-day extension of the re-hearing deadline, which was granted, thus the new deadline for EPA to seek re-hearing is December 3, 2008.

IV. Scope of the Proposal

EPA is proposing a regulation that would strengthen the existing controls on discharges from construction activity by establishing technology-based effluent limitations guidelines and new source performance standards for the C&D point source category. This proposal, if implemented, would significantly reduce the amount of sediment, TSS, turbidity and other pollutants discharged from construction sites due to construction activities. EPA estimates that today's proposed rule would cost $1.9 billion dollars per year. These estimates do not include costs for Alaska, Hawaii and the U.S. territories because EPA lacked data on the amount of construction occurring in these areas. However, EPA does expect that some construction sites in these areas would incur compliance costs as a result of today's proposal. EPA solicits data that can be used to estimate the number of acres of construction activity that occurs annually in these areas.

The proposed rule would establish a set of non-numeric effluent limitations requiring dischargers to provide and maintain effective erosion control measures, sediment control measures, and other pollution prevention measures to minimize and control the discharge of pollutants in stormwater and other wastewater from construction sites. The rule would specify particular minimum BMPs to meet the effluent limitations requiring effective erosion control and pollution prevention.

In addition, reflecting current requirements in the EPA CGP, sites disturbing 10 or more acres at one time would be required to install a sediment basin to contain and settle sediment from stormwater runoff. The proposed rule would require minimum standards of design for sediment basins; however, alternatives that control sediment discharges in a manner equivalent to sediment basins would be authorized where approved by the permitting authority.

Finally, reflecting the BAT and NSPS levels of control, for certain large sites located in areas of high rainfall energy and with soils with significant clay content, discharges of stormwater from the site would be required to meet a numeric effluent limit on the allowable level of turbidity. The numeric turbidity limit is 13 nephelometric turbidity units (NTUs). The turbidity limit is intended to remove fine-grained and slowly settling or non-settleable particles contained in stormwater. Particles such as clays and fine silts contained in stormwater discharges from C&D sites typically cannot be effectively removed by conventional stormwater BMPs (such as sediment basins and sediment traps) that rely solely on settling unless sufficient detention time or additives are implemented. The technology basis for the turbidity limit is active treatment systems (ATS), which consists of polymer-assisted clarification followed by filtration.

In addition to this proposed option, EPA is specifically soliciting comment on setting a turbidity limit in the range of 50 to 150 NTUs (or some other number) based on passive treatment, instead of ATS. See section IX.A.5.a of today's proposal for additional discussion of this alternative approach.

EPA considered several other regulatory approaches while developing this proposed rule, such as specifying certain design criteria for sediment basins, or using different site size, rainfall, or soil type thresholds for determining which sites would be required to comply with a turbidity limit. EPA also considered setting BAT and NSPS equal to the proposed BPT level of control, based on non-numeric BMP-based effluent limitations, as well as an expanded version of today's proposed rule. EPA requests comment on these alternative regulatory approaches. Details of the proposed rule and alternative approaches considered are described in this notice, the Development Document, Economic Analysis, and Environmental Assessment (see the Supporting Documentation section of this notice) and additional documentation is contained in the record.

V. Overview of the Construction and Development Industry and Construction Activities

The C&D point source category covers firms classified by the Census Bureau into two North American Industry Classification System (NAICS) codes.

• Construction of Buildings (NAICS 236) includes residential, nonresidential, industrial, commercial and institutional building construction.

• Heavy and Civil Engineering Construction (NAICS 237) includes utility systems construction (water and sewer lines, oil and gas pipelines, power and communication lines); land subdivision; highway, street, and bridge construction; and other heavy and civil engineering construction.

Other types of entities not included in this list could also be regulated.

A single construction project may involve many firms from both subsectors. The number of firms involved and their financial and operational relationships may vary greatly from project to project. In typical construction projects, the firms identifying themselves as “operators” under a construction general permit are usually general building contractors or developers. While the projects often engage the services of specialty contractors such as excavation companies, these specialty firms are typically subcontractors to the general building contractor and are not separately identified as operators in stormwater permits. Other classes of subcontractors such as carpentry, painting, plumbing and electrical services typically do not apply for, nor receive, NPDES permits. The types and numbers of firms in the construction industry are described in more detail in the Development Document and the Economic Analysis.

Construction on any size parcel of land almost always calls for a remodeling of the earth. Therefore, actual site construction typically begins with site clearing and grading. Earthwork activities are important in site preparation because they ensure that a sufficient layer of organic material (ground cover and other vegetation, especially roots) is removed. The size of the site, extent of water present, the types of soils, topography and weather determine the types of equipment that will be needed during site clearing and grading. Material that will not be used on the site may be hauled away. Clearing activities involve the movement of materials from one area of the site to another or complete removal from the site. When grading a site, builders typically take measures to ensure that new grades are as close to the original grade as possible to reduce erosion and stormwater runoff. Proper grade also ensures a flat surface for development and is designed to attain proper drainage away from the constructed buildings. A wide variety of equipment is often used during excavation and grading. The type of equipment used generally depends on the functions to be performed and on specific site conditions. Shaping and compacting the earth is an important part of site preparation. Earthwork activities might require that fill material be used on the site. In such cases, the

fill must be spread in uniform, thick layers and compacted to a specific density. An optimum moisture content must also be reached. Graders and bulldozers are the most common earth-spreading machines, and compaction is often accomplished with various types of rollers. If rock is to be removed from the site, the contractor must first loosen and break the rock into small pieces using various types of drilling equipment or explosives. (Adapted from Peurifoy, Robert L. and Oberlender, Garold D. (1989). Estimating Construction Costs (4th ed.). New York: McGraw Hill Book Company.)

Once materials have been excavated and removed and the ground has been cleared and graded, the site is ready for construction of buildings, roads, and/or other structures. During construction activity, the disturbed land can remain exposed without vegetative cover for a substantial period of time. Where the soil surface is unprotected, soil particles and other pollutants are particularly susceptible to erosion and may be easily washed away by rain or snow melt and discharged from the site. Permittees typically use a combination of erosion and sediment control measures designed to prevent mobilization of the soil particles and capture of those particles that do mobilize and become entrained in stormwater from the C&D site. In most cases these control measures take the form of BMPs, but in some cases construction sites actively treat a portion of the discharge using filtration or other treatment technologies. Erosion and sediment control measures are described further in the Development Document.

VI. Summary of Data Collection Activities

In developing today's proposal, EPA gathered and evaluated technical and economic data from various sources. EPA also used data collected previously to develop the 2002 proposed C&D rule and the 2004 withdrawal of the proposed rule.

EPA used these data to estimate costs, pollutant loading reductions, environmental benefits and economic impacts of various regulatory options. This section summarizes EPA's data collection efforts.

A. State Data

EPA compiled and evaluated existing state program information about the control of construction site stormwater. EPA collected data by reviewing state construction general permits, Web sites, summary references, state regulations, and erosion and sediment control design and guidance manuals. A summary of criteria and standards for construction site stormwater erosion and sediment control that are implemented by states are presented in Appendix A of the Development Document for this proposed rulemaking. EPA did not collect information from counties or municipalities regarding current construction site stormwater requirements. EPA relied on state-level requirements to characterize requirements in all areas of the state. So, if county or municipal requirements are more stringent than state-level requirements for control of construction site stormwater discharges, EPA's baseline estimates of costs and pollutant reductions would not reflect these more stringent requirements currently in place. Therefore, certain components of EPA's cost and loadings estimates for the regulatory options may be overestimates. In addition, EPA did not account for those sites that would already be required to meet a turbidity limit. For example, some construction sites around the country are already required to meet numeric effluent limits for turbidity that are comparable to EPA's proposed turbidity limit. EPA has not accounted for these sites in its analysis of costs and loading reductions, although the number of these sites is likely to be only a small fraction of construction sites nationwide.

B. National Land Cover Dataset (NLCD)

The NLCD provides a national source of data on land cover. EPA used these data to estimate the amount of land across the U.S. that was converted to development (e.g., from forest or farmland to residential communities), which in turn was used to estimate the amount of acreage that may be subject to the requirements of the C&D rule.

The Multi-Resolution Land Characteristics Consortium (MRLC) has produced the NLCD datasets that created a 30-meter resolution land cover data layer over the conterminous United States using remote sensing data. There are approximately 24 billion data points from remote sensing data that comprise the NLCD database. NLCD data is publicly available for the years 1992 and 2001.

Due to new developments in mapping methodology, new sources of input data, and changes in the mapping legend for the 2001 National Land Cover Database (NLCD 2001), direct comparison between NLCD 2001 and the 1992 National Land Cover Dataset (NLCD 1992) is difficult. Thus, MRLC prepared the NLCD 1992/2001 Land Cover Change Product (see

http://www.mrlc.gov/change_detection.asp

). The NLCD 1992/2001 Land Cover Change Product was developed to offer more accurate direct change analysis between the two products. This land cover change map and all documents pertaining to it are considered “provisional” until a formal accuracy assessment can be conducted. Detailed definitions and discussion of the NLCD 1992/2001 Land Cover Change Product is summarized in the Development Document.

EPA estimated the annual number of acres of land converted to development in the U.S. and used that estimate as a surrogate measure of the acres of construction activities subject to national effluent guidelines regulations, since no national database of the number and size of construction activities exists. EPA used estimates of the amount of construction activity occurring in each state based on NLCD data as a basis for calculating state-level compliance costs. NLCD data was also used to estimate the amount of construction activity occurring in each of the watersheds in the U.S. based on the EPA Reach File cataloging system (discussed below). Watershed level data (along with other data sources) was used to estimate the quantity of construction activities and the associated pollutant loads occurring in each watershed and to link these loads to stream reaches for modeling of water quality improvements and benefits estimates.

C. Enhanced River Reach File 1.2 (ERF1)

EPA used the EPA Reach File 1.2 dataset (ERF1) to summarize land cover change in drainage area units (or watersheds). ERF1 for the Conterminous United States is a vector database of approximately 700,000 miles of streams and open waters in the conterminous United States. ERF1 was prepared by EPA in 1982 from National Oceanographic and Atmospheric Administration (NOAA) aeronautical charts having a scale of 1:500,000. ERF1 contains 67,171 watersheds with a minimum size of 247 acres (1 km

2

) and an average size of 30,182 acres (122 km

2

). ERF1 serves as the foundation for SPARROW (Spatially Referenced Regressions [of nutrient transport] on Watershed) modeling (see Section XIV of this proposal for a discussion of SPARROW).

D. NPDES Notice of Intent (NOI) Data

As stated above, when a discharger wishes to be authorized to discharge under a general permit, it files a NOI to be covered under the general permit. EPA used NOI data to estimate the distribution of construction activity by site size and development type. Using NOI data, EPA broadly characterized the

construction industry into three land use types (residential construction, non-residential construction and road/highway construction). Differentiation of construction activities by site size and project type was also done for EPA's technical and economic analyses. EPA used NOI data from approximately 138,000 permit applications, containing data from 38 States for construction activities occurring primarily between the mid-1990s and 2006. Depending on the state, the number of NOI records available ranged from fewer than 10 to more than 10,000. The data are available either from a database of permits processed directly by EPA (referred to as the EPA NOI database) or from per-state databases obtained independently.

E. Soils Data

EPA used the State Soil Geographic (STATSGO) data compiled by Penn State University (

http://www.soilinfo.psu.edu/

) in order to estimate variation in soil types nationwide. The variation in soil types found within the United States is a significant factor in estimating sediment discharges, pollutant load reductions, and stormwater pollution prevention costs for construction sites. EPA used the STATSGO soils data in support of the loadings and removal estimates for this proposal. EPA used the Revised Universal Soil Loss Equation (RUSLE) in combination with the soils data to determine soil erosion rates from model construction sites in different areas of the country. EPA used these estimates, in combination with estimates of pollutant removal efficiencies for the various technologies evaluated, to estimate sediment discharges from C&D sites under baseline conditions and under each regulatory option evaluated. Although EPA was not able to find a national database of measured sediment concentrations in treated and untreated construction site stormwater runoff, EPA did find monitoring data from several states and compared these measured concentrations to the estimate concentration based on RUSLE. A discussion of this comparison is provided below in section IX. F. Additional details on the soil data collected can be found in the Development Document.

F. NOAA Rainfall Data

Variations in rainfall depth and intensity are also important factors in determining erosion rates, sediment discharges, pollutant load reductions and control technology costs for construction sites. In order to account for variations in rainfall patterns, EPA collected rainfall data for one indicator city within each of the 48 conterminous states. Data for each of these indicator cities were used as point estimates for estimating rainfall depths and intensities for construction activities for the entire state. A major urban area was chosen as the indicator city in each state; which in most cases was the capital city.

For each indicator city, precipitation data was gathered and analyzed using the National Oceanic and Atmospheric Administration (NOAA) National Weather Service (NWS) Precipitation Frequency Data Server (PFDS), NOAA Atlas 14, a series of maps presented in older NWS publications, and NOAA Atlas 2 (Precipitation Frequency Atlas of the Western United States (1973)). Alaska and Hawaii, as well as the U.S. territories, were not included in this analysis because EPA lacked sufficient data on the annual amount of construction occurring in these areas. More details on EPA's analysis can be found in the Development Document.

G. Parameter Elevation Regressions on Independent Slopes Model (PRISM)

PRISM is a climate mapping system that was used to estimate the annual acres that would be subject to the regulatory options given various annual rainfall cutoffs. Using PRISM GIS layers of average annual precipitation along with RF1-level estimates of annual acres of new construction, EPA was able to estimate acres that would be subject to various regulatory options given various average annual precipitation cutoffs.

H. Revised Universal Soil Loss Equation (RUSLE) R Factors

EPA used maps of rainfall-runoff erosivity factors (or R factors) contained in the RUSLE documentation. These maps, in GIS form, along with RF1-level estimates of annual acres of new construction, were used to estimate acres that would be subject to regulations given various R factor values.

I. Economic Data

EPA utilized various economic data sources in developing today's proposal. The primary data source is the 2002 Economic Census, conducted every five years by the U.S. Census Bureau. The U.S. Small Business Administration (SBA) and Census Bureau also provide important information in Statistics of U.S. Business (SUSB). SUSB provides firm-level data that is particularly important for the firm and industry impact assessment and for the small entity analysis. An important source of project level data is Reed Construction, a commercial construction industry data service that collects and reports information on multifamily, commercial/institutional, and industrial construction projects undertaken nationally. EPA assigned baseline financial characteristics—balance sheet, income statement, and metrics of financial performance and condition—to each of the model firms as defined by NAICS sector and revenue size range, from financial statement information reported by Risk Management Association's (RMA) publication, Annual Statement Studies. The Census Bureau's 2006 American Community Survey (ACS) was used to characterize new home prices and lot sizes (2006 was chosen because it is the most recent year for which the required Metropolitan Statistical Area (MSA)-level data are available from the Census).

VII. Characteristics of Discharges From Construction Activity

The nature of construction activity is that it changes, often significantly, many elements of the natural environment. Typically, construction activities involve clearing the land of vegetation, digging, earth moving and grading, followed by the active construction period when the affected land is usually left denuded and the soil compacted, often leading to an increase in the peak discharge rate and the total volume of stormwater discharged and higher rates of erosion. During the land disturbance period, affected land is generally exposed after removal of grass, rocks, pavement and other protective ground covers. Where the soil surface is unprotected, soil and sand particles may be easily picked up by wind and/or washed away by rain or snow melt. Typically, the water carrying these particles eventually reaches a water body.

Discharges from construction activity have been documented to increase the loadings of several pollutants in the receiving waterbodies. The most prominent and most widespread pollutant discharged from C&D sites is sediment. The level of sediment is often identified through the measurement of the pollutants' turbidity, suspended solids, total suspended solids (TSS), suspended sediment concentration (SSC), and/or settleable solids. CWA section 304(a)(4) identified suspended solids as a conventional pollutant and in 1978 EPA defined “suspended solids” as “total suspended solids (non-filterable) (TSS)” and stated that TSS “is a laboratory measure of the organic and inorganic particulate matter in wastewater which does not pass through a specified glass filter disk.” See 40 CFR

401.16; 43 FR 32857, 32858 (July 28, 1978). Turbidity and settleable solids are non-conventional pollutants. See CWA section 301(b)(2)(F); 304(a)(4);

Rybachek

v.

EPA,

904 F.2d 1276, 1291-92 (9th Cir. 1990). The Agency defined “turbidity” as “an expression of the optical property that causes light to be scattered and absorbed rather than transmitted with no change in direction of flux level through the sample * * * caused by suspended and colloidal matter such as clay, silt, finely divided organic and inorganic matter and plankton and other microscopic organisms.” 40 CFR 136.3; 72 FR 11200, 11247 (March 12, 2007). (See Section IX for a discussion of why EPA proposes turbidity as the desired pollutant to control in determining the appropriate technology).

Stormwater discharges can have highly variable levels of pollutants. Available data show that turbidity levels range from as low as 10-50 NTU to several thousand NTU. When the denuded and exposed areas contain nutrients, pathogens, metals or organic compounds, these other pollutants are likely to be carried at increased rates (relative to discharges from undisturbed areas) to surrounding waterbodies via stormwater and other discharges (e.g., inadequately controlled construction equipment wash water). Discharges of these pollutants from construction activities can cause changes in the physical characteristics of waterbodies, such as pH, water temperature, or stream flow velocity, as well as changes in biological characteristics such as aquatic species abundance and composition.

Actions taken to stabilize disturbed areas of the C&D site can include seeding to restore vegetative cover. When fertilizers or herbicides are applied to these areas, a portion of the chemicals applied may become entrained in stormwater and will be discharged from the site. Fertilizers contribute nutrients such as nitrogen and phosphorus to the wastestream.

Discharges from construction activity are expected to contain varying concentrations of metals, some of which may be contributed by equipment used onsite for grading and other construction activities. Metals are also naturally present in soils and, by removing vegetative cover and increasing erosion and sediment loss, there will likely be an increase in the amount of metals discharged from the C&D site. Metals present as a contaminant or additive in fertilizers and other soil amendments may serve as another source of pollutants in the stormwater discharge.

Fuels and lubricants are maintained onsite to refuel and maintain vehicles and equipment used during construction activities. These products, should they come in contact with stormwater and other site discharges, would contribute toxic organic pollutants. Pathogenic pollutants can be present in stormwater that comes into contact with sanitary wastes where portable sanitation facilities are poorly located or maintained.

The environmental impacts associated with discharges from construction sites are described in section XIV.

VIII. Description of Available Technologies

A. Introduction

As described in Section VII, construction activity results in the discharge of pollutants to waters of the U.S. These discharges can be controlled by applying site design techniques that preserve or avoid areas prone to erosion and through the effective use of a combination of erosion and sediment control measures. Construction activities should be managed to reduce erosion and retain sediment on the C&D site. Erosion and sedimentation are two separate processes and the practices to control them differ. Erosion is the process of wearing away of the land surface by water, wind, ice, gravity, or other geologic agents. Sedimentation is the deposition of soil particles, both mineral and organic, which have been transported by water, wind, air, gravity or ice (adapted from North Carolina Erosion and Sediment Control Planning and Design Manual, September 1, 1988).

Erosion control measures are intended to minimize dislodging and mobilizing of sediment particles. Sediment control measures are controls that serve to capture particles that have mobilized and are entrained in stormwater, with the objective of removing sediment and other pollutants from the stormwater discharge. An overview of available technologies and practices is presented below; see the Development Document for more complete descriptions. Many states and local governments and other entities have also published detailed manuals for erosion and sediment control measures, and other stormwater management practices.

B. Erosion Control Measures

The use of erosion control measures is widely recognized as the most important means of limiting soil detachment and mobilization of sediment. The controls described in this notice are designed to reduce mobilization of soil particles and minimize the amount of sediment and other pollutants entrained in discharges from construction activity. Erosion can be minimized by a variety of practices. The selection of control measures that will be most effective for a particular site is dictated by site-specific conditions (e.g., topography, soil type, rainfall patterns). The main strategies used to reduce erosion include minimizing the time bare soil is exposed, preventing the detachment of soil and reducing the mobilization and transportation of soil particles off-site.

Decreasing the amount of land disturbed can significantly reduce sediment detachment and mobilization, as well as overall erosion and sediment control costs. This can be accomplished by reducing the overall area of disturbed land or by phasing construction so that only a portion of the site is disturbed at a time. Another effective approach is to schedule clearing and grading events to reduce the probability that bare soils will be exposed to rainfall.

Managing stormwater flows on the site can be highly effective at reducing erosion. Typical practices include actively managing off-site and on-site stormwater using diversion berms, conveyance channels and slope drains to avoid stormwater contact with disturbed areas. In addition, stormwater should be managed using energy dissipation approaches to prevent high runoff velocities and concentrated flows that are erosive. Vegetative filter strips are often considered as sediment controls, but they can also be quite effective at dissipating energy and reducing the velocity (and thus erosive power) of stormwater.

After land has been disturbed and construction activity has ceased on any portion of the site, exposed soils should be covered and stabilized immediately. Vegetative stabilization using annual grasses is a common practice used to control erosion. Polymers, physical barriers such as geotextiles, straw, rolled erosion control products and mulch are other common methods of controlling erosion. These materials and methods are intended to reduce erosion where soil particles can be initially dislodged on a C&D site, either from rainfall, snow melt or up-slope runoff.

The effectiveness of erosion control measures is dependent on periodic inspection and identification and correction of deficiencies (e.g., after each storm event). Erosion control measures alone will not eliminate the mobilization of soil particles and such controls must be used in conjunction with sediment control measures.

C. Sediment Control Measures

Despite the proper use of erosion control measures, some sediment detachment and movement is inevitable. Sediment control measures are used to control and trap sediment that is entrained in stormwater runoff. Typical sediment controls include perimeter controls such as silt fences constructed with filter fabric, straw bale dikes, berms or swales. Trapping devices such as sediment traps and basins and inlet protectors are examples of in-line sediment controls. Sediment traps and basins are commonly used approaches for settling out sediment eroded from small and large disturbed areas. Their performance can be enhanced using baffles and skimmers and active treatment processes such as electrocoagulation, filtration, and chemically enhanced settling (e.g., polymer addition).

Active treatment systems are typically used in conjunction with other sediment controls to improve pollutant removals, especially to improve removals of fine-grained and slowly settling or non-settleable particles and turbidity contained in stormwater. Unless sufficient detention time is provided or additives are implemented, particles such as clays and fine silts contained in stormwater discharges from construction sites typically cannot be effectively removed by conventional stormwater BMPs (such as sediment basins and sediment traps) that rely solely on gravity settling. EPA has identified several demonstrated technologies capable of achieving significant reductions of these particles. Based on the information in the record, electrocoagulation, polymer clarification, and chitosan-enhanced filtration treatment technologies are demonstrated as being capable of achieving low levels of turbidity in stormwater discharges.

The active treatment systems EPA has evaluated operate by destabilizing the suspended particles by various mechanisms, aggregating them into larger particles that are easier to remove through settling or filtering. In addition to physical characteristics (e.g., particle surface area, density) that impede timely settling by gravity, these small particles (often clay particles) typically are substantially influenced by net electrical repulsive forces at particle surfaces that prevent the particles from joining together. Coagulation refers to the process whereby these repulsive electrical forces are reduced, allowing particles to come into contact with one another. Flocculation refers to the agglomeration of the destabilized particles by joining and bridging to form larger particles. Following coagulation/flocculation, the densified floc can more easily and effectively be removed via gravitational settling or media filtration (e.g., sand, gravel, bag, or cartridge filters).

Electrocoagulation treatment uses an electrical field to disturb the natural electrical charges of the colloidal particles suspended in stormwater, enabling the particles to coagulate and flocculate, and facilitating gravity settling. This settling may be followed by filtration prior to discharge of the stormwater.

Polymer clarification can operate as a batch process whereby a polymer is added to stormwater contained in a basin. The polymer causes clays and other fine particles to flocculate and gravity settle. Once the turbidity reaches the necessary value and other permit requirements are met, the stormwater is discharged from the basin. Polymer clarification can also be used in flow-through systems. In this application, liquid polymer is injected into the influent to the sediment basin or gel or solid polymer is added by placing polymer-filled socks or “floc logs” in channels or pipes carrying sediment-laded runoff into the basin. Stormwater flowing over the socks or logs dissolves the solid polymer, and turbulence at the basin inflow point facilitates mixing and aids in the coagulation/flocculation process.

Chitosan-enhanced filtration is a process that adds a polymer (in this instance, a polymer produced from the chitin in crab shells) to the stormwater to promote flocculation. The flocculated stormwater is then passed through one or more filtration steps and, if permit conditions are met, can be discharged.

These active treatment systems are often equipped with automated instrumentation to monitor stormwater quality, flow rate, and dosage control for both influent and effluent flows.

It has been suggested that, while operating active treatment systems that use polymers to reduce the turbidity of stormwater, construction site dischargers may overuse polymers and, in doing so, introduce toxicity or cause other adverse effects. EPA believes toxic effects from discharges treated to meet a turbidity limit should not be occurring and such events would be indicative of a poorly operated treatment system. Polymers are widely used at a variety of wastewater treatment systems and facilities throughout the country, and EPA is not aware of any studies indicating that polymer addition to treat stormwater from construction sites using ATS has been found to pose a significant risk to water quality at those facilities. There are ample regulatory (i.e., enforcement actions) and financial (e.g., chemical costs) disincentives for dischargers to willfully overuse polymers in their treatment systems. In addition, vendors have indicated that dosages of polymers are carefully metered in ATS systems. Upon closer review of the matter, it appears that this concern has been raised due to anecdotal suggestions, rather than documented evidence of actual discharge events causing toxic effects. To date, EPA has not identified any documented cases where the use of a polymer to treat C&D stormwater discharges caused an adverse effect in the receiving waters. Also, Washington and other States have researched toxicity of some polymers and established a sound basis for testing and significant controls on dosage and usage. For example, Washington State has established protocols for residual chemical and toxicity testing for ATS systems and has required vendors to receive state approval. However, California, in a draft permit fact sheet describing chemical treatment, states the following:

“These systems can be very effective in reducing the sediment in storm water runoff, but the systems that use additives/polymers to enhance sedimentation also pose a potential risk to water quality (e.g., operational failure, equipment failure, additive/polymer release, etc.). We are concerned about the potential acute and chronic impacts that the polymers and other chemical additives may have on fish and aquatic organisms if released in sufficient quantities or concentrations. In addition to anecdotal evidence of polymer releases causing aquatic toxicity in California, the literature supports this concern. For example, cationic polymers have been shown to bind with the negatively charged gills of fish, resulting in mechanical suffocation. Due to potential toxicity impacts, which may be caused by the release of additives/polymers into receiving waters, residual polymer monitoring and toxicity requirements have been established in this General Permit for discharges from construction sites that utilize an ATS in order to protect receiving water quality and beneficial uses.” (see DCN 41137).

Therefore, EPA recognizes the merits of ensuring that chemical additives are properly used. EPA solicits information and data that quantify the number of instances where overuse of polymers occurred, the circumstances resulting in such overuse, and the actual or potential environmental impacts associated with such events. In addition, EPA solicits comments on the need for approaches (either voluntary or regulatory) to prevent or minimize the potential for such instances and the need for EPA to

develop guidance on use of polymers at construction sites.

More detailed descriptions of sediment and erosion control measures can be found in the Development Document.

D. Other Construction and Development Site Management Practices

Construction activity generates a variety of wastes and wastewater, including concrete truck rinsate, municipal solid waste (MSW), trash, and other pollutants. Construction materials and chemicals should be handled, stored and disposed of properly to avoid contamination of runoff. Dischargers utilize various practices to manage these wastes and minimize discharges to surface waters, including:

• Protecting construction materials, chemicals and fuels and lubricants from exposure to rainfall;

• Limiting exposure of freshly placed concrete to rainfall;

• Segregating stormwater and other wastewaters from fuels, lubricants, sanitary wastes, and chemicals such as fertilizers, pesticides and herbicides;

• Neat and orderly storage of chemicals, pesticides, fertilizers, and fuels that are being stored on the site;

• Prompt collection and management of trash and sanitary waste;

• Prompt cleanup of spills of liquid or dry materials.

IX. Development of Effluent Limitations Guidelines and Standards

A. Description of the Regulatory Options Considered

In developing today's proposal, EPA evaluated several different options for reducing pollutant discharges from construction activity. The options evaluated by EPA are intended to control the discharge of sediment, turbidity and other pollutants in stormwater and other wastewater from C&D sites. Construction activity typically involves clearing, grading and excavating of land areas. Prior to construction, these land areas may have been agricultural, forested or other undeveloped lands. Construction can also occur as redevelopment of existing rural or urban areas, or infill development on open space within existing developed areas. During the C&D process, vegetation or surface cover is typically removed and underlying soils become more susceptible to detachment by rainfall and erosion by stormwater runoff. Soil is often compacted by construction equipment, reducing the infiltration capacity of underlying soils and increasing stormwater discharge rates. Sediments and other pollutants contained in stormwater can and often are transported off-site and discharged from construction sites. Today's proposal provides regulatory tools to improve erosion and sediment control measures and pollution prevention measures on C&D sites to minimize and control stormwater and other discharges from construction activity.

Certain limitations being proposed today are common to each regulatory option. These common requirements consist of a set of non-numeric effluent limitations that require dischargers to provide and maintain effective erosion control measures, sediment control measures, and other pollution prevention measures to minimize the discharge of pollutants in stormwater and other wastewater from construction sites. These non-numeric effluent limitations included in each regulatory option are described in Section IX.B below.

B. Effluent Limitations Included in All Regulatory Options

EPA's preferred approach is twofold: First, prevent the discharges of sediment and other pollutants from occurring through the use of effective site-specific planning, erosion control measures and pollution prevention measures; and second, control discharges that do occur through the use of effective sediment control measures. Under each regulatory option, dischargers would be required to meet non-numeric effluent limitations requiring them to minimize and control discharges from the site by providing and maintaining effective erosion and sediment control measures and pollution prevention measures.

Dischargers would be required to prevent soil erosion and minimize the discharge of sediment from all areas of the site by providing and maintaining effective erosion control measures. Erosion controls are considered effective when bare soil is uniformly and evenly covered with vegetation or other suitable materials, stormwater is controlled so that rills and gullies are not visible, and channels and streambanks are not eroding. Dischargers would be required to provide and maintain recognized and accepted erosion control measures, including stabilizing disturbed soils immediately after clearing, grading, or excavating activities have permanently or temporarily ceased (i.e., when such activities have been stopped on a portion of the site and will not resume for a period exceeding 14 calendar days). In addition, dischargers would be required to minimize the amount of soil exposed and control stormwater within the site to prevent soil erosion by using effective erosion control measures. Stormwater discharges leaving the site would also need to be controlled to prevent channel and streambank erosion and erosion at outlets.

The following list of principles and practices are generally recognized and accepted as effective erosion controls and would be provided in the rule to help guide the selection, design, and implementation of control measures to meet the effluent limitations on individual construction sites.

• Preserve topsoil and natural vegetation.

• Minimize soil compaction.

• Sequence or phase construction activities to minimize the areas disturbed at any one time.

• Stabilize disturbed areas using temporary or permanent vegetation, and controls such as mulch, geotextiles, or sod.

• Minimize the disturbance of steep slopes, and where such slopes are disturbed implement erosion controls designed to control soil erosion on slopes.

• Establish and maintain natural buffers around surface waters.

• Minimize the construction of stream crossings.

• Divert stormwater that may run onto the site away from any disturbed areas of the site.

Dischargers would also be required to meet non-numeric effluent limits requiring that they provide and maintain effective sediment controls to minimize the discharge of sediment and other pollutants from C&D sites. Sediment control measures implemented at the site would include, at a minimum, the following:

• Establishing perimeter controls for any portion of the down-slope and side-slope perimeter where stormwater will be discharged from disturbed areas of the site.

• Establishing and using stabilized construction entrances and exits that control sediment discharges from the site. Ensuring that vehicles entering and exiting the site use such access points to prevent tracking of sediment onto roads or other areas that convey sediment to surface waters. Removing any sediment or other pollutants, including construction materials, from paved surfaces daily. Washing sediment or other pollutants off paved surfaces into storm drains would be prohibited.

• Establishing and using controls and practices to minimize the introduction of sediment and other pollutants to storm drain inlets that receive stormwater discharges from the site.

• Controlling sediment and other contaminants from dewatering activities. Discharges of dewatering wastes are prohibited unless treated in a sediment basin or similar control measure.

Each regulatory option includes pollution prevention measures that would minimize or prohibit the discharge of pollutants from a variety of sources and activities at C&D sites. Each option would prohibit discharges of construction wastes, trash, sanitary wastes, and wastewater from washout of concrete, paint, and other such materials. The regulatory options would also prohibit the discharge of fuels, oils, and other materials used in vehicle and equipment operation and maintenance. The discharge of wastewater from washing vehicles and equipment where soaps or solvents are used would be prohibited. The discharge of pollutants resulting from the washing of equipment and vehicles using only water would also be prohibited, unless wash waters were treated in a sediment basin or alternative control that provides equivalent or better treatment. Dischargers would be required to implement measures to minimize the exposure of stormwater to building materials, landscape materials, fertilizers, pesticides, herbicides, detergents, and other liquid or dry products. In addition, dischargers would be required to implement appropriate spill prevention and response procedures for these materials.

C. Options for BPT, BCT, BAT and NSPS

EPA considered the following three regulatory options for today's proposal.

•

Option 1

Each C&D site subject to the rule would be required to implement the limitations described above in Section IX.B. In addition, certain larger sites would be required to install and maintain sediment basins or equivalent sediment controls. Specifically, for portions of sites that drain to one location and will have 10 or more acres disturbed at one time, dischargers would be required to install a sediment basin to control and treat the stormwater discharges. The proposed rule would impose minimum standards of design and performance for sediment basins. The basin would be required to provide storage for a calculated volume of stormwater (called the water storage volume) from a 2-year, 24-hour storm from each disturbed acre drained plus a sediment storage volume of at least an additional 1,000 cubic feet, until final stabilization of the disturbed area. Alternatively, a sediment basin providing a water storage volume of 3,600 cubic feet per acre drained plus the sediment storage volume would be required. To ensure adequate retention time to facilitate settling of sediment particles, the proposed rule would require that the effective length of the basin must be at least four times the width of the basin and that the water storage volume be designed to drain over a period of at least 72 hours using a surface outlet (such as a skimmer), unless otherwise designated by the permitting authority. The size of the basin that would be required is based on the size of the drainage area that will have vegetation removed and soils disturbed (i.e., if the total drainage area is 15 acres, but only 13 acres of this area will have vegetation removed and soils disturbed during the course of the project and the remaining 2 acres will remain vegetated and stormwater is directed around both the disturbed area and the sediment basin, then the storage volume can be sized based on 13 acres).

In addition, the design of the sediment basin would be required to address site-specific factors such as amount, frequency, intensity and duration of stormwater runoff; soil types; and other factors affecting pollutant removal efficacy. For example, particle settling characteristics, and thus pollutant removal efficacy, can be affected by physical parameters of the basin such as inlet and outlet velocities, basin surface area, and basin depth and volume necessary to provide sufficient storage for sediment load and stormwater runoff. Effective erosion and sediment controls are generally recognized as including actions to divert stormwater away from disturbed areas of the site, so that sediment erosion is reduced and sediment controls, such as basins, are not overwhelmed by stormwater volumes.

To minimize carryover and discharge of suspended particles from the sediment basin, the basins would be required to incorporate an outlet device designed to remove water from the top of the water column in order to minimize the amount of sediment and other pollutants entrained in the discharge. This can be accomplished by using technologies such as a siphoning outlet, surface skimmer or floating weir.

Recognizing that there may be impediments to using sediment basins in some instances or that alternative approaches may provide better controls depending on site-specific conditions, the proposed rule would authorize dischargers to use alternative controls equivalent to sediment basins where approved by the permitting authority.

EPA encourages dischargers to use improved sediment basin designs that incorporate features such as baffles and to increase the length to width ratio of the basin to maximize detention time and settling. The use of these practices may significantly improve the performance of sediment basins in certain cases. The North Carolina Department of Transportation (NCDOT) has developed draft specifications for baffles in sediment basins (see DCN 43083). EPA solicits comments on whether porous baffles, as described in the draft NCDOT specifications, should be minimum requirements for all sediment basins nationwide. EPA also requests comments on the costs and effectiveness of baffles used in sediment basins, either alone or in combination with skimmers and polymer addition. EPA also solicits comments on the detention time requirements for sediment basins contained in today's proposal, and whether the proposed rule should include other specific detention time, overflow rate or other design or performance requirements for sediment basins. EPA also solicits comments on whether the regulation should require that sediment basins be designed to remove a specified particle size. EPA also requests comments on whether sediment basin designs should be required to address downstream channel erosion by requiring peak or discharge rates to match predevelopment conditions, and for what storm events such a standard should apply.

Option 1 is estimated to cost approximately $132 million per year (2008 $), not including costs for Alaska, Hawaii and the U.S. territories, and reduce discharges of pollutants by 670 million pounds annually. Monetized benefits of Option 1 are estimated to be $18 million per year. The cost estimates for Option 1 only include costs for larger sediment basins in those states whose sizing requirements are less stringent than those contained in the proposal. These cost estimates do not include any additional costs for implementing skimmers or the additional volume for sediment storage. EPA assumed that these costs would not impact sediment basin costs significantly. Skimmers can be purchased from commercial suppliers, or fabricated on-site. Also not included are costs for deep ripping and decompaction of soils, and several other required BMPs that are not currently part of the CGP or most state permits. EPA solicits comments on the cost assumptions of Option 1. The efficacy of Option 1 (percent of raw stormwater

sediment load removed) may be underestimated because only the basins are modeled in the loading analysis. Removals due to other on-site BMPs have not been modeled or included in the analysis.

While developing and evaluating Option 1, EPA considered several possible variations for sediment basin requirements. One approach would have eliminated flexibility for dischargers to use a 3600 cf/acre basin in lieu of the 2-year, 24-hour basin. In effect, all sites required to install a sediment basin under Option 1 would have been required to construct a basin sized to treat runoff from the 2-year, 24-hour storm (or use equivalent control measures). EPA estimated that this variation of Option 1 would cost approximately $1.09 billion per year. EPA also considered an approach that, in addition to specifying a particular size of basin, would require that the sediment basin be sized and constructed to enable settling of a specified-size particle—e.g., 10-micron particles. This approach would be a design standard rather than a numeric limitation on the sediment basin effluent. For example, the California Stormwater Quality Association Construction Handbook (see DCN 43017) contains an example of designing a sediment basin to remove a specified particle size standard based on wet sieve analysis for the 10 micron particle for a 10-year, 6-hour storm event. EPA estimates, using this approach, that sediment basins required to remove particles greater than 10 microns nationwide would cost approximately $1.7 billion per year. More information about these potential sediment basin approaches is presented in the Development Document. EPA solicits comment on whether Option 1 or other variations described here would be appropriate regulatory approaches and, if so, why, based on the statutory requirements of CWA section 304, they should be considered to represent BPT, BCT, BAT, or NSPS level of control for this industry.

•

Option 2

The requirements that would be established under Option 2 incorporate all of the Option 1 requirements. In addition, a numeric limit on turbidity of stormwater discharges would apply to sites that meet certain criteria for size of the site, average clay content of the soil (with clay content being defined as soil particles less than 2 microns in diameter), and rainfall erosivity factor (“R factor”) as defined by the Revised Universal Soil Loss Equation (see

Predicting Soil Erosion by Water: A Guide to Conservation Planning With the Revised Universal Soil Loss Equation (RUSLE),

United States Department of Agriculture, Agriculture Handbook Number 703, January 1997). Option 2 would establish a numeric effluent limit on the turbidity of stormwater discharges for any site that meets all three of the following criteria: (1) Average soil clay content of more than 10 percent; (2) annual R factor of 50 or more; and (3) has a size of 30 or more acres. The numeric turbidity standard would apply to discharges produced from rainfall events up to the local 2-year, 24-hour storm. Any volume in excess of the 2-year, 24-hour storm would be exempt from the turbidity standard. The turbidity limitation would apply to these sites in addition to the Option 1 requirements (i.e., such sites would also be required to implement the non-numeric erosion and sediment control measures described under Option 1). Under Option 2, dischargers would be required to monitor stormwater discharges for turbidity, which can be done either by using automated instrumentation or with a portable, hand-held turbidimeter or similar device. Sites with a common drainage location that serves an area with 10 or more acres of land disturbed land at one time that are not required to meet the turbidity requirement, either because the total size of the site is less than 30 acres, the R factor is less than 50 or the average clay content of soils is less than 10 percent, would be required to install sediment basins as described under Option 1. Site size for sites subject to the proposed turbidity limit is based on the total size of the site, not the amount of disturbed acres or some other subset of the site. Any site which is 30 acres or larger regardless of how much of the site will be disturbed would be subject to the turbidity limit if they also meet the R factor and soil clay content thresholds.

By considering the construction site's soil clay content, this option takes into account the pollutant reductions that are achievable using the erosion control measures and traditional sediment control measures (i.e., those other than active treatment systems) included in the proposed rule. These more traditional approaches to controlling stormwater discharges can be very effective in soils with low clay content where the entrained sediment is amenable to gravity settling. However, as the amount of clay in the soil rises, gravity settling processes are less effective and processes to enhance the removal of pollutants from stormwater are necessary. By applying the proposed turbidity limit in Option 2 to sites with 10% or more clay content, the proposed rule would achieve significant reductions of the slowly settling or non-settleable particles and turbidity contained in stormwater. In order to remove these fine-grained particles from stormwater discharges, active treatment technologies, such as those described in Section VIII, typically would need to be employed. The information in the record shows that these systems can achieve low levels of turbidity in the stormwater discharges.

While it is impossible to predict the weather several months in advance of construction, for many areas of the country, there are definite optimal periods for conducting construction activities in order to limit soil erosion, such as a dry season when rain tends to fall less frequently and with less force. When feasible, this is the time to disturb the earth, so that the site is stabilized by the time the seasonal wet weather returns. The R factor is intended to reflect consideration of the amount and intensity of precipitation expected during the time the earth will be exposed.

The method for determining a site's R factor is based on the Universal Soil Loss Equation (USLE) developed by the U.S. Department of Agriculture (USDA) in the 1950s to help farmers conserve topsoil. The USLE has been updated to the Revised USLE (RUSLE). Using a computer model supported by decades worth of rainfall data, USDA established estimates of rainfall erosivity factors (R) for locations throughout the country. These R factors are used as surrogate measures of the impact that rainfall has on erosion from a particular site. The R factor represents the driving force for erosion, taking into consideration total rainfall, intensity and seasonal distribution of the rain. Isoerodent maps depicting the R factor in various parts of the country have been created by USDA and are included in Chapter 2 of Agriculture Handbook Number 703.

While developing and evaluating Option 2, EPA considered several possible variations for the applicability of a limitation on turbidity of stormwater discharges. One approach would replace the R factor criteria with one based on total annual rainfall for the site location. Under this approach, EPA preliminarily considered values of 20 inches and 40 inches of total annual rainfall. EPA considers the R factor approach better than total annual rainfall at addressing stormwater discharges because the R factor captures both rainfall energy (a function of the volume of rainfall and runoff) and intensity (which has direct bearing on the erosive power of a rainfall event). EPA has structured the regulatory

option accordingly. However, since R factors have not been calculated for all areas of Alaska and the U.S. territories, a criterion of 20-inches total annual rainfall (30-year average using National Weather Service records) has been retained as a substitute for R factor for construction sites in those locations unless an R factor applicable to the construction site is calculated.

EPA also considered approaches that would apply the turbidity effluent limitation to larger sites (e.g., 50 acres instead of 30 acres) or with higher clay content of the soil (e.g., 20 percent instead of 10 percent clay). More information about these potential approaches is presented in the Development Document. EPA solicits comment on whether Option 2 or other combinations of rainfall, clay content and acreage limitations like those described above would be more appropriate regulatory approaches and, if so, why, based on the statutory requirements of CWA section 304, they should be considered to represent BPT, BCT, BAT, or NSPS level of control for this industry. Another option would be to base Option 2 on disturbed acres, instead of the total site size. EPA solicits comments on this approach.

EPA evaluated the advantages and disadvantages of establishing a limitation on turbidity vs. total suspended solids (TSS) in stormwater discharges from construction sites. EPA selected turbidity for two reasons. First, EPA is specifically targeting fine silt, clay and colloidal particles in stormwater runoff. These particles have small diameters and frequently contain a surface charge that prevents agglomeration. As a result, these particles typically do not settle in sediment basins and are not effectively removed by conventional BMPs such as silt fences, which have a large pore diameter. Consequently, discharges from sites with appreciable clay soils may have low TSS concentrations but may still have high turbidity levels. Second, turbidity can be easily measured in the field while TSS requires collection of a sample and analysis in a laboratory. Since most BMPs and treatment systems are flow-through systems, TSS would not be a practical means of estimating compliance because permittees would not be able to verify whether or not they had met the standard before discharging. With turbidity, permittees can measure turbidity levels in discharges continuously and adjust treatment parameters accordingly or recycle effluent if they are in danger of exceeding the turbidity limit. For these reasons, EPA believes that turbidity is a more appropriate measure of effectiveness and can be implemented more easily than TSS. EPA requests comments on this approach.

Option 2 is estimated to cost $1.9 billion per year (2008 $), not including costs for Alaska, Hawaii and the U.S. territories, and reduce discharges of pollutants by 27 billion pounds annually, with a sensitivity analysis estimate of 6.2 billion pounds annually. Monetized benefits of Option 2 are estimated to be $333 million annually.

•

Option 3

Under Option 3, all sites with common drainage locations that serve an area with 10 or more acres disturbed at one time would be required to comply with the turbidity effluent limitation (in addition to the non-numeric effluent limitations in Option 1). This option does not establish thresholds for R factor (or total annual rainfall) or soil type (i.e., clay content). Under this option, all other sites (i.e., sites with less than 10 acres disturbed at one time) would be required to implement the requirements described under Option 1 (for sites with common drainage locations that serve an area of less than 10 acres disturbed at one time).

Option 3 is estimated to cost $3.8 billion per year (2008 $), not including costs for Alaska, Hawaii and the U.S. territories, and reduce discharges of pollutants by 50 billion pounds annually, with a sensitivity analysis estimate of 11.1 billion pounds annually. Monetized benefits of Option 3 are $470 million annually. EPA notes that its modeling of acres subject to the options evaluated is based on total site size instead of amount of disturbed area on a site. EPA does not have data that can be used to estimate the percentage of a site that is typically disturbed. For example, if a site is 15 acres, but only 7 acres were to be disturbed, then under Option 3 this site would not be subject to the turbidity standard. However, EPA has estimated costs for Option 3 for all sites that, in total, are more than 10 acres. Therefore, to the extent that EPA has overestimated the quantity of acres that would be subject to Option 3, EPA's estimates of costs, benefits and loadings reductions for turbidity controls under Option 3 would also be overestimated.

With regard to Option 3, depending on the location of the construction site and time of year, it is possible that relatively little rain would be expected during construction (based on historical average rainfall patterns) and perhaps dischargers could opt to not install active treatment systems. However, such an approach would expose permittees to the risk of discharging stormwater that exceeds the turbidity limit. On the other hand, taking an overly precautionary approach could result in sites installing treatment equipment that sees little or no use. EPA seeks comment on this issue.

Also with regard to Option 3, EPA has also considered the availability of treatment systems capable of achieving the turbidity effluent limit, as well as whether there is sufficient vendor capacity to meet the demand that would be presented by extending the turbidity effluent limit to all construction sites disturbing more that 10 acres at a time. Option 3 means that substantial numbers of active treatment systems would need to be manufactured and mobilized, along with sizeable levels of vendor support, in a relatively short period of time as NPDES permits incorporating the ELGs and NSPS are issued.

EPA solicits comments on this issue.

D. Option Selection Rationale for BPT

EPA proposes to select Option 1 as the basis for establishing BPT effluent limitations. The requirements established by Option 1 are well-established for construction activities in all parts of the country and are generally consistent with and in some cases more stringent than the control measures currently in place under EPA's Construction General Permit. Some requirements of Option 1 are more stringent than many state general permits, while other requirements are less stringent than some state general permits. EPA has determined that Option 1 represents a level of control that is technologically available and economically practicable. EPA considered the non-water quality environmental impacts of this option and found them to be minimal and thus acceptable. Selecting Option 1 as BPT for this point source category is consistent with the CWA and regulatory determinations made for other point source categories, in that the Option 1 requirements represent limitations based on the average of the best performance of facilities within the C&D industry.

See Weyerhauser Co.

v.

Costle,

590 F.2d 1011, 1053-54 (D.C. Cir. 1978). As stated in Section III, EPA assesses cost-reasonableness of BPT effluent limitations by considering the cost of treatment in relation to the effluent reduction benefits achieved. EPA has determined that the pollutant reduction benefits achieved by Option 1 justify the costs. We have typically described this as dollars/pound and compare the results with other rules. The incremental costs of Option 1 are approximately $132 million per year

(2008 $). EPA anticipates that construction sites in approximately 11 states would incur costs to comply with the proposed Option 1 BPT requirements requiring sediment basins generally consistent with the EPA CGP. As noted above, the efficacy of this option may be underestimated.

EPA rejected Options 2 and 3 because EPA views BPT performance as the first level of technology-based control representing the average of the best performance. EPA's record does not indicate that meeting a turbidity limit, even for the subset of facilities identified in Option 2 would represent today's average of the best performance and it would not represent the BPT level of control for this point source category. EPA requests comment on what should be considered BPT for this category.

E. Option Selection Rationale for BAT and NSPS

1. Selection Rationale

EPA proposes to select Option 2 as the basis for BAT and NSPS. This option would require all C&D sites to implement the non-numeric effluent limitations described for Option 1, as well as requiring certain sites to meet a numeric limitation of 13 NTU (nephelometric turbidity units) to control turbidity for stormwater discharges. Turbidity is being regulated in this proposed rule as a nonconventional pollutant and an indicator pollutant for the control of other pollutants associated with sediment and materials on construction sites that can become entrained in stormwater discharges from construction sites, including metals and nutrients. Turbidity, measured as NTU, which in construction site runoff primarily reflects sediment, is a nonconventional pollutant because it is not identified as either a toxic or conventional pollutant under the CWA. See CWA section 301(b)(2)(F); 304(a)(4); 40 CFR 401.16;

Rybachek

v.

EPA,

904 F.2d 1276, 1291-92 (9th Cir. 1990). Turbidity is “an expression of the optical property that causes light to be scattered and absorbed rather than transmitted with no change in direction of flux level through the sample * * * caused by suspended and colloidal matter such as clay, silt, finely divided organic and inorganic matter and plankton and other microscopic organisms.” 40 CFR 136.3; 72 FR 11200, 11247 (March 12, 2007). In this rulemaking, EPA is identifying turbidity as a pollutant of concern in construction site discharges. By providing a measure of the sediment entrained in stormwater discharges, turbidity is an indicator of the degree to which sediment and other pollutants associated with sediment and found in stormwater discharges are reduced. Turbidity is also a more effective measure of the presence of fine silts, clays and colloids, which are the particles in stormwater discharges that EPA is specifically targeting in today's proposal.

Metals, nutrients, and other toxic and nonconventional pollutants are naturally present in soils, and can also be contributed by equipment/materials used during construction or by activities that occurred at the site prior to the construction activity. Many of these pollutants are present as particulates and will be removed with other particles. Dissolved forms of pollutants are often absorbed or adsorbed to particulate matter and can also be removed along with the particulates (i.e., sediment). EPA has determined that effluent limitations that reduce turbidity in the stormwater discharge will also achieve reductions of the other pollutants of concern. Demonstrating compliance with a turbidity limit would be relatively easy and inexpensive for construction site dischargers to implement. Hand-held turbidity meters (turbidimeters) can be used to measure turbidity in discharges, or data loggers coupled with in-line turbidity meters can be used to automatically measure and log turbidity measurement reducing labor requirements associated with sampling. In addition, the use of turbidity meters will provide dischargers with immediate, real-time information on the efficacy of their treatment systems and sediment control measures to facilitate timely adjustments of system operation where necessary.

The requirements of Option 2 have been demonstrated to be technologically available. Active treatment systems have been used and are currently being used at several hundred construction sites throughout the country. Construction sites where these active treatment systems have been used are primarily located in California, Oregon and Washington, with some in Florida, Maryland, Vermont and other states. Oregon requires sites to meet a 160 NTU benchmark if the site is discharging to a waterbody listed as not meeting applicable water quality standards under section 303(d) or a waterbody with a total maximum daily load (TMDL) for sediment and turbidity. Washington has turbidity benchmark limits that are set at values relative to the turbidity in the receiving steam. Benchmark requirements (e.g., in the context of the Oregon and Washington permits), as opposed to numeric effluent limits, require the facility to take some action to address the potential water quality issue such as additional monitoring or BMP review and do not result in a permit violation. Vermont requires what it defines as “moderate risk” projects to take corrective action if turbidity exceeds 25 NTUs. Also, several other states have turbidity limitations or standards that are either in draft permits (such as California), are set relative to background levels (Georgia), or are set only for specific regions or specific waterbodies within the state (such as the Lake Tahoe Basin of California) or for specific construction projects (such as construction of a new runway at the Sea-Tac airport). To comply with these turbidity-based requirements, dischargers have used the active treatment systems described previously—electrocoagulation, polymer clarification, and chitosan-enhanced sand filtration, as well as other approaches. The information in the record demonstrates the efficacy of these treatment systems, showing that they consistently achieve very low levels of turbidity in stormwater discharges. A summary of existing state requirements are contained in the TDD.

EPA also considered the recommendations of the National Research Council (NRC). EPA commissioned the NRC to evaluate the NPDES stormwater program and make recommendations for improvement of the program. The Water Sciences and Technology Board released the report Urban Stormwater Management in the United States (Committee on Reducing Stormwater Discharge Contributions to Water Pollution, National Research Council, National Academies Press) in October of 2008. The report is the product of a 2-year process undertaken by a 15-member committee of national experts.

While the report did not specifically endorse numeric effluent limits for construction sites, the report did contain several recommendations, including that “Numeric enforcement criteria can be used to define what constitutes an egregious water quality violation at construction sites and provide a technical criterion to measure the effectiveness of erosion and sediment control practices.” The study continues to report that “A maximum turbidity limit would establish definitive criteria as to what constitutes a direct sediment control violation and trigger an assessment for remediation and prevention actions. For example, local erosion and sediment control ordinances could establish a numeric turbidity limit of 75 Nephelometric

Turbidity Units (NTU) as an instantaneous maximum for rainfall events less than an inch (or a 25 NTU monthly average) and would prohibit visible sediment in water discharged from upland construction sites. While the exact turbidity limit would need to be derived on a regional basis to reflect geology, soils, and receiving water sensitivity, research conducted in the Puget Sound of Washington indicates that turbidity limits in the 25 to 75 NTU can be consistently achieved at most highway construction sites using current erosion and sediment control technology that is properly maintained (Horner

et al.,

1990). If turbidity limits are exceeded, a detailed assessment of site conditions and follow-up remediation actions would be required. If turbidity limits continue to be exceeded, penalties and enforcement actions would be imposed. Enforcement of turbidity limits could be performed either by state, local, or third party erosion and sediment control inspectors, or—under appropriate protocols, training, and documentation—by citizens or watershed groups.”

EPA recognizes that the turbidity limits discussed in the report are more like the action levels specified by Washington and other states, rather than binding numeric effluent limitations being proposed by EPA. However, EPA's analysis of ATS effluent data from more than 6,000 data points indicates that a limit of 13 NTUs is technologically available.

California assembled a blue ribbon panel to evaluate, among other things, the feasibility of establishing numeric effluent limits from construction sites (see DCN 41010). The blue ribbon panel found that “It is the consensus of the Panel that active treatment technologies make Numeric Limits technically feasible for pollutants commonly associated with stormwater discharges from construction sites (e.g. TSS and turbidity) for larger construction sites. Technical practicalities and cost-effectiveness may make these technologies less feasible for smaller sites, including small drainages within a larger site, as these technologies have seen limited use at small construction sites. If chemical addition is not permitted, then Numeric Limits are not likely feasible.”

EPA's selection of Option 2, which requires a turbidity limit only for larger sites, is therefore consistent with the panel's conclusion. EPA notes that although the panel mentions that a numeric limit is not feasible without chemical addition (e.g., polymers) there are technologies available (such as electrocoagulation) that do not use polymers. Further, data in the literature suggests that a somewhat higher limt (e.g., 50-150 NTU) may be achievable using enhanced sediment basin design practices without relying on ATS. An option based on this approach is discussed in more detail below.

The panel, in determining that numeric effluent limits are technically feasible, did express concerns, including cost-effectiveness for small sites, toxicity of treatment chemicals, and the potential for discharges with low TSS and turbidity into receiving waters with high background levels (such as in some arid and semi-arid areas) contributing to channel erosion. EPA has determined that Option 2 addresses these concerns, because the turbidity standard only applies to larger sites and does not apply in arid and semi-arid areas because of the R-factor applicability criteria. EPA is soliciting comment on the need for regulatory requirements or guidance to address the concerns regarding potential toxicity of treatment chemicals. EPA also solicits comments on whether and how toxicity concerns should factor into EPA's BAT determination.

Based on the analysis conducted for this proposed rule, EPA believes that the requirements of Option 2 are economically achievable. Option 2 is projected to have a total industry compliance cost, once fully implemented in NPDES permits, of $1.9 billion per year (2008 $). Since EPA expects that the effluent guidelines requirements will be implemented over time as states revise their general permits, EPA expects full implementation within five years of the effective date of the final rule, currently required to be promulgated in December 2009, which would be 2014. EPA estimates that, once fully implemented, there will be nearly 82,000 firms that perform work falling within scope of Option 2. Average annual revenue for these in-scope firms is $544.14 billion (2008 $). Option 2 compliance costs are 0.35 percent of in-scope firm revenues. Of these 82,000 fims, 6,396 would incur costs under option 2. These firms have revenues of $409.02 billion (2008$) and costs are 0.46% of revenues for firms incurring costs.

Under Option 2, an estimated 774 firms (0.9 percent of all in-scope firms) are estimated to incur compliance costs exceeding 1 percent of annual revenue, and 76 firms (0.1 percent of in-scope firms) are expected to incur compliance costs exceeding 3 percent of revenue. When using EPA's assumption that under normal business conditions firms can pass most of their compliance costs along to customers (85 percent of costs for residential construction and 71 percent for non-residential), there are 20 firms estimated to incur (net) costs exceeding 1 percent of revenue, and no firms expected to incur (net) costs exceeding 3 percent of revenue.

EPA has attempted to analyze the secondary impacts on home buyers when costs are fully passed through. As part of this analysis, EPA converted compliance costs into the likely dollar increase in housing prices. Making assumptions about likely terms of financing, this was converted to an increase in the monthly mortgage payment, where the percent increase in home price is approximately equal to the percent increase in mortgage payment. This analysis assumes there is no change in the set of households that are new home buyers because of the proposed regulation. EPA then used income distribution data to estimate the change in the number of households in the market for a new home that would qualify to purchase the median and lower quartile priced new home under the higher monthly mortgage payment. This analysis was performed using the median and lower quartile priced new home for each metropolitan statistical area (MSA). For the MSA's, the weighted average median priced for a home is $322,000, and the percent increase would be 0.65%. In this way, EPA has attempted to characterize how the potential increase in mortgage payment may affect housing affordability. EPA estimated that 2,195 of these prospective home purchasers would no longer qualify to purchase a median priced home affected by the rule, and 3,243 would no longer qualify to purchase a new lower quartile priced home affected by the rule. However, this approach only looks at two specific points along the spectrum of housing prices and therefore does not represent the total number of households potentially impacted by the rule. EPA is interested in developing an analysis reflective of the number of households that would likely be adversely affected by the proposed regulation, and solicits comment on appropriate methodology and any data that would be required to conduct such an analysis. Based on our analysis thus far EPA believes that the secondary impacts to new home buyers are affordable.

Under normal business conditions with cost pass-through (85% residential and 71% non-residential) EPA estimates the number of firms expected to incur financial stress as a result of the regulatory requirements to be 147 firms which represents 0.2 percent of in-scope firms and 2.3 percent of firms incurring

costs under Option 2. A total of 103 firms are estimated to experience negative business value and be at risk of closure due to regulatory requirements, which represents 0.1 percent of in-scope firms and 1.6 percent of total firms incurring costs. These impact measures are not additive, as they evaluate different aspects of a firm's financial viability, and the same firm may be counted under more than one measure. EPA recognizes that this industry is subject to business cycles and performed an adverse business conditions analysis to assess the impacts during an economic downturn. The adverse business conditions case assumes no cost pass-through as well as other less favorable operating factors for the industry. No-cost pass through is a rigid assumption where all impacts are born by the permitee, and there are no secondary impacts on builders who buy lots or buyers of the finished construction. For the adverse case, the results for Option 2 show the number of firms expected to incur financial stress as a result of the regulatory requirements to be 479 firms, which represents 0.6 percent of in-scope firms and 8.3 percent of firms incurring costs under Option 2. A total of 662 firms are estimated to experience negative business value and be at risk of closure due to regulatory requirements, which represents 0.9 percent of in-scope firms and 11.4 percent of firms incurring costs. Nevertheless, given the measures of financial impact, in terms of percentage of in-scope firms and firms incurring costs, EPA considers the rule to be economically achievable by the construction industry. EPA requests comments on its economic achievability analyses and on its proposed determination that Option 2 is economically achievable.

EPA's analysis shows that Option 2 has acceptable non-water quality environmental impacts. The pollution prevention, sediment and erosion control measures included in the proposed rule, including the collection and treatment of stormwater at some construction sites, will not result in a significant incremental increase in the energy consumption, air emissions, or generation of solid waste at construction sites.

EPA has proposed to reject Option 1 as the basis for BAT and NSPS in part because it would not represent the best available or best demonstrated technology for controlling discharges from this industry. Narrative effluent limitations, such as those contained in Option 1, to prevent and minimize erosion and sediment dischargers have been a feature of NPDES permits for many years. Controls are available and demonstrated that provide a higher degree of pollution reduction than Option 1 and consistently provide low turbidity values, making a numeric turbidity limit feasible. In addition, in considering economic achievability of the option, EPA believes that the measures of affordability EPA has used in the past, facility closure and firm failure, and the firm stress metric used in Regulatory Flexibility Analysis also considered here (percent of revenue lost and whether that measure is above 1 or 3 percent) demonstrate that Option 2 can be reasonably borne by the industry.

EPA has also proposed to reject Option 3 as the basis for BAT and NSPS, due primarily to the total industry cost (estimated at $3.8 billion annually). Option 3, once fully implemented, would cost $1.9 billion more annually than Option 2. EPA closely evaluated whether establishing a turbidity limit on all construction sites disturbing more than 10 acres at a time represents the BAT or NSPS level of control—and believes that it does not. Option 3 would require all construction sites, in every part of the country and at all times of the year, to meet a numeric effluent limitation on turbidity if the construction activity disturbs 10 or more acres of land at a time. Construction sites that have soils containing relatively little clay (e.g., a site in coastal Florida with sandy soils) or with low rainfall-runoff erosivity (such as those in certain parts of Idaho) can likely control the discharge of sediments and other pollutants through effective use of the erosion and sediment control measures included in the non-numeric effluent limitations being proposed today. With relatively little of the difficult-to-settle clay present, and with low rainfall energy, sediment production is expected to be low and EPA expects much of the sediment to be removed from stormwater through the use of effective sediment controls. Therefore, EPA believes that requiring these sites to meet a numeric turbidity limit, including the additional costs for monitoring that a numeric turbidity limit would impose, does not represent BAT for these sites. EPA solicits comments on this approach.

In light of the high total cost of Option 3 and the appropriateness of ELG and NSPS turbidity limits in arid areas and at construction sites where rainfall energy is low and soils contain little clay, EPA believes that Option 3 does not represent the best available or best demonstrated technology for the C&D point source category.

In summary, EPA believes that Option 2 is technologically available, economically achievable, and has acceptable non-water quality environmental impacts. EPA believes that establishing a numeric turbidity limitation on a segment of the point source category represents best available and best available demonstrated technology for the C&D industry, striking an appropriate balance that addresses the factors EPA is required to consider under the CWA and the nature of stormwater discharges from construction sites. In addition, EPA has determined that the non-numeric effluent limitations being proposed under Option 2 represent best available and best available demonstrated technology for all dischargers in the C&D industry.

Although EPA has proposed Option 2 as a basis for BAT and NSPS, EPA is soliciting comment on the appropriateness of the numeric turbidity limit of 13 NTUs and the technology basis (i.e., ATS) for Option 2. EPA has identified information that indicates that a limit in the range of 50-150 NTUs might be met by relying on passive, rather than active, treatment systems. Passive treatment systems consist of a number of techniques that do not rely on pumping of stormwater or mechanical filtration and that are not as complex, do not cost as much and do not utilize as much energy as ATS.

Data in the literature indicate that passive systems may be able to provide a high level of turbidity reduction at a significantly lower cost than active treatment systems. For example, McLaughlin (see DCN 41005) evaluated several modifications to standard sediment trap designs at the North Carolina State University Sediment and Erosion Control Research and Education Facility (SECREF). He evaluated standard trap designs as contained in the North Carolina Erosion and Sediment Control Manual utilizing a stone outlet structure as well as alternative designs utilizing a skimmer outlet and various types of porous baffles. Baffle materials tested included silt fence, jute/coconut and tree protection fence tripled over. Tests were conducted using simulated storm events in which sediment was added to stormwater at flows of 10 to 30 liters per second. McLaughlin found that a standard gravel outlet did not significantly reduce turbidity values. Average turbidity values in the basin were 843 NTUs, while average turbidity in the effluent was 758 NTUs using the standard outlet. Use of a skimmer instead of a standard gravel outlet reduced turbidity to an average of 353

NTUs. Additional tests were conducted to evaluate the addition of polyacrylamide (PAM) through the use of floc logs. Floc logs are a solid form of PAM which are designed to be placed in flowing water. They are typically anchored by a rope or by placing them in a mesh bag or cage either in open channels or in pipes. As the water flows over the floc logs, the PAM dissolves somewhat proportional to flow. The floc logs typically have substantial amounts of non-PAM components, which are intended to improve PAM release, maintain the physical integrity of the blocks and enhance PAM performance (McLaughlin—Soil Facts; Chemical Treatments to Control Turbidity on Construction Sites). McLaughlin found that addition of PAM to sediment traps resulted in average effluent turbidities of 152 NTUs using a rock outlet and 162 NTUs using a skimmer outlet. For one set of tests, use of a standard stone outlet along with PAM was able to attain an average effluent turbidity of 51 NTUs, while tests with jute/coconut mesh baffles with PAM were only slightly higher, at 71 NTUs.

Warner (see DCN 43071) evaluated several innovative erosion and sediment controls at a full-scale demonstration site in Georgia as part of the Erosion and Sedimentation Control Technical Study Committee (known as “Dirt II”). The Dirt II project consisted, among other things, of field monitoring as well as modeling of erosion and sediment control effectiveness at construction sites. The demonstration site was a 50-acre lot in a suburban area near Atlanta where a school was being constructed. In total, 22.5 acres of the site was disturbed. A comprehensive system of erosion and sediment controls were designed and implemented to mimic pre-developed peak flow and runoff volumes with respect to both quantity and duration. The system included perimeter controls that were designed to discharge through multiple outlets to a riparian buffer, elongated sediment controls (called seep berms) designed to contain runoff volume from 3 to 4 inch storms and slowly discharge to down-gradient areas, multi-chambered sediment basins designed with a siphon outlet that discharged to a sand filter, and various other controls. Extensive monitoring was conducted at the site. For one particularly intense storm event of 1.04 inches (0.7 inches of which occurred during one 27 minute period), the peak sediment concentration monitored prior to the basin was 160,000 mg/L while the peak concentration discharged from the sand filter after the basin was 168 mg/L. Effluent turbidity values ranged from approximately 30 to 80 NTUs. Using computer modeling, it was shown that discharge from the sand filter, which flowed to a riparian buffer, was completely infiltrated for this event. Thus, no sediment was discharged to waters of the state from the sand filter for this event. For another storm event, a 25-year rainfall event of 3.7 inches occurred over a 2 day period. Effluent from one sand filter during this storm was 175 mg/L while discharge from a second sand filter was 100 mg/L, except for the first-flush data point occurring at the beginning of the storm event.

There are other references in the literature describing the various types of passive treatment systems and the efficacy of passive treatment systems. One potential application of a passive system would be to add liquid polymer, such as PAM, to the influent of a conventional sediment basin. This can be accomplished by using a small metering pump to introduce a pre-established dose of polymer in the influent pipe or channel. If the polymer is added in a channel far enough above the basin, then turbulent mixing in the channel can aid in the flocculation process. Otherwise, some sort of provision may need to be made to provide mixing in the basin to produce flocs. Polymers typically used in this particular application include PAM, chitosan, polyaluminum chloride (PAC), aluminum sulfate (alum) and gypsum. With any polymer, jar tests should be performed beforehand with soils present on the site in order to determine an appropriate polymer type and dosage.

The Auckland (New Zealand) Regional Council conducted several trials to evaluate the effectiveness of chemical flocculants and coagulants in improving settling of suspended sediment contained in sediment laden runoff from earthworks sites (Auckland Regional Council. The Use of Flocculants and Coagulants to Aid the Settlement of Suspended Sediment in Earthworks Runoff—Trials, Methodology and Design. Technical Publication 227. June, 2004). Trials were conducted using both liquid and solid forms of flocculants. Trials were initially conducted on two projects: a highway project and residential development.

The highway project (ALPURT) evaluated both a liquid polymer system and solid polymers. Liquid polymers evaluated were alum and PAC and solid polymers evaluated were all polyacrylamide products (Percol AN1, Percol AN2 and Percol CN1). Bench tests indicated that AN2 performed best among the solid polymers and that both PAC and alum were effective in flocculating the soils present on the site.

Following bench testing of the polymers, liquid and solid dosing systems were developed. For the liquid dosing system, initial consideration was given to a runoff proportional dosing system which would include a weir or flume for flow measurement, an ultrasonic sensor and signal generating unit, and a battery driven dosing pump. These components, together with costs for necessary site preparatory work, chemical storage tanks and a secure housing, were estimated to cost approximately $12,000 (1999 NZ $) per installation. An alternative system was developed that provided a chemical dose proportional to rainfall. This rainfall driven system, which did not require either a runoff flow measurement system or a dosing pump, had a total cost of $2,400 (1999 NZ $) per installation.

The rainfall driven system operated by collecting rainfall in a rainfall catchment tray. Rainfall into this tray was used to displace the liquid treatment chemical from a storage tank into the stormwater diversion channel prior to entering the sediment basin. The size of the catchment tray was determined based on the size of the catchment draining to the basin, taking into consideration the desired chemical dosage rate obtained from the bench tests. Accumulated rainfall from the catchment tray fills a displacement tank that floats in the chemical storage tank. As the displacement tank fills with rainfall and sinks, liquid chemical is displaced from the chemical storage tank and flows via gravity to the dosing point.

Field trials of the liquid treatment system using alum were conducted at the ALPURT site. The authors report that the system performed “satisfactorily in terms of reduction of suspended solids under a range of rainfall conditions varying from light rain to a very high intensity, short duration storm, where 24mm of rainfall fell over a period of 25 minutes.” Suspended solids removal for the intense storm conditions was 92% with alum treatment. For a similar storm on the same catchment with the same retention pond without alum treatment, suspended solids removal was about 10%.

Field trials at the ALPURT site were also conducted using PAC. In total, 21 systems were used with contributing catchments ranging between 0.5 and 15 hectares (approximately 1 to 37 acres). The overall treatment efficiency of the PAC treated basins in terms of suspended sediment reduction were

reported to be between 90% and 99% for ponds with good physical designs. The authors noted that some systems did not perform as well due to mechanical problems with the system or physical problems such as high inflow energy (which likely caused erosion or sediment resuspension) or poor separation of basin inlets and outlets. The suspended solids removal for all ponds incorporating PAC ranged from 77% to 99.9%, while the removal in a pond not incorporating PAC ranged from 4% to 12%. Influent suspended solids concentrations for the systems incorporating PAC ranged from 128 to 28,845 mg/L while effluent concentrations ranged from 3 to 966 mg/L. In comparison, influent suspended solids concentrations for the untreated ponds were approximately 1,500 mg/L while effluent concentrations were approximately 1,400 mg/L. The authors also noted that dissolved aluminum concentrations in the outflow from the basins treated with PAC, in most cases, were actually less than the inflow concentrations, and were also less than the outflow concentrations from the untreated ponds. Outflow aluminum concentrations in the PAC treated ponds ranged from 0.01 to 0.072 mg/L. The ALPURT trials generally indicate that a relatively simple, passive treatment system using liquid polymers can result in significant reductions in suspended sediment concentrations, even with influent concentrations in excess of 25,000 mg/L. Although some effluent concentrations were as high as several hundred mg/L, the majority were below 100 mg/L. This indicates that a passive liquid polymer system, perhaps coupled with a gravity sand filter or distributed discharge to a vegetated buffer (as described by Warner, 2001) could be used to meet a numeric effluent limit for turbidity at a significantly lower cost than ATS. EPA solicits comments on this issue.

Field trials of polymer treatment using solid forms of PAM by the Auckland Regional Council were conducted at the ALPURT site as well as a residential project (Greenhithe). Trials at the ALPURT site were conducted by placing the floc blocks in plastic mesh bags in plywood flumes through which the runoff from the site was directed. Initial trials encountered problems due to the high bedload of granular material, which accumulated against and stuck to the floc logs inhibiting solubility of the polymer. The system was reconfigured to incorporate a forebay before the flumes in order to facilitate removal of the bedload fraction. The authors noted that while this system was generally effective at low flow rates, it was difficult to control dosage rates and sediment accumulation in the flumes continued to be a problem. The authors concluded that “Floc Block treatment has a high potential for removal of suspended solids from stormwater with consistent quality, particularly for small catchments; when flow balancing can be achieved prior to treatment.”

Field trials were also conducted at the Greenhithe site, which was a 4 hectare (approximately 10 acre) residential project. As with the ALPURT trial, a flume was constructed and placed in the flow path immediately before the sediment basin. Results of the trials were mixed. The authors noted several problems with the floc logs, such as drying and breakdown of the logs due to prolonged exposure to the air and softening and breakdown during periods of prolonged submergence. Sediment accumulation around the logs and breakdown continued to be a problem. Incorporating an effective sediment forebay and limiting bedload are suggestions for increasing performance. In addition, the authors recommended soaking the floc logs in water to allow hydration before use and periodic spraying with water as ways to limit drying of the floc logs. EPA notes that similar problems with floc logs have been noted by some construction site field inspectors (see DCN 41109) and by McLaughlin (see DCN 43082). EPA solicits comments on the effectiveness of floc logs as components of passive treatment systems. EPA also solicits comments on any operational or maintenance considerations that should accompany use of solid forms of polymers.

Results of the PAC studies at the ALPURT sites have led the Auckland regional council to require chemical treatment for any site that produces more than 1.5 metric tons of (net) sediment as determined by the Universal Soil Loss Equation. Sites that exceed this threshold will require chemical treatment in accordance with a site chemical treatment plan. Exceptions include projects of less than one month duration and sites with granular volcanic soils and sand areas. Chemical treatment may also not be required if bench testing indicates that chemical treatment will provide no improvement in sediment removal efficiency (see DCN 41111). EPA solicits comments on the approach adopted by the Auckland Regional Council and its applicability to construction and development site discharges in the U.S.

In addition to (or in place of) adding polymers to sediment basins, polymers can be introduced on other areas of the site as a soil stabilization measure or as components of other BMPs. For example, McLaughlin (DCN 41005) evaluated adding polymer to check dams on highway projects. Various other researchers evaluated PAM as a soil stabilization agent. There are a number of documents in the administrative record for this rulemaking describing the use of PAM.

The data from these studies indicate that various types of passive treatment systems that utilize both solid and liquid forms of polymers have been reported to be effective in reducing turbidity levels in discharges from construction and development sites. EPA is therefore soliciting comments on whether a turbidity limitation of 50 to 150 NTUs (or some other value) based on passive treatment systems should instead serve as the basis for BAT limitations and NSPS. EPA solicits comments on the costs, pollutant removal effectiveness and effluent quality attainable by passive treatment systems and on the technical basis for establishing a particular a numeric turbidity limit of 50 to 150 NTUs (or some other value). EPA also solicits comment on the ability to reliably meet a 50 to 150 NTU limit using passive systems on different types of construction and development sites and in locations across the country and on the appropriate monitoring requirements that should accompany passive treatment systems. EPA also solicits comments on the applicability of a 50 to 150 NTU (or some other value) standard. Specifically, since passive systems may be less costly and require less expertise and operator supervision than active treatment systems, EPA solicits comments on whether a standard based on passive systems should apply more broadly and to more sites than are covered by EPA's proposed Option 2, or if EPA should establish a tiered set of turbidity limitations, reflecting variation of site parameters such as site size, rainfall patterns, soil types, soil erodibility, or some other parameter and the specific thresholds that should apply to such parameters. EPA also requests comment on whether it should develop an enhanced non-numeric limitation based on the types of passive technologies discussed above without establishing a specific numeric limit, as well as whether it should consider an “action level” based approach such as is required by Washington and several other states through their construction general permits. EPA further requests comment on the feasibility and burden

on permitting authorities of an “action level” established nationally.

2. Definition of “New Source” for the Construction and Development Category

EPA interprets the definition of “new source” at CWA section 306(a)(2) as not including discharges associated with construction activity. Section 306(a)(2) of the CWA defines “new source” as “any source, the construction of which is commenced after publication of proposed regulations * * *” The plain language of section 306 excludes C&D sites because a construction site cannot itself be constructed. Further, the term “source” is defined in 306(a)(3) of the CWA to mean “any building, structure, facility, or installation * * *” or in-other-words sources that are the product of the construction, not the construction activity itself. Additionally, there is an independent definition of “construction” in section 306(a)(5). If construction sites were intended to be “new sources,” the Agency finds it illogical that there would be a separate definition for “construction” or that there would be a requirement in section 306 of the CWA that “sources” be “constructed” prior to becoming “new sources.”

Though EPA interprets the CWA not to apply NSPS under section 306 of the CWA to the C&D point source category, the District Court order enjoins EPA to propose and promulgate NSPS. Therefore, EPA proposes to define “new source” for purposes of part 450 as any source of stormwater discharge associated with construction activity that itself will result in an industrial source from which there will be a discharge of pollutants regulated by a new source performance standard in subchapter N other than today's rulemaking. (All new source performance standards promulgated by EPA for categories of point sources are codified in subchapter N). The definition of new source proposed today for purposes of part 450 would mean that the land-disturbing activity associated with constructing a particular facility would itself constitute a “new source” when the facility being constructed would be a “new source” regulated by new source performance standards under section 306 of the CWA. For example, construction activity that builds a new pharmaceutical plant covered by 40 CFR 439.15 would be subject to new source performance standards under 40 CFR 450.24.

F. Option Selection Rationale for BCT

EPA is proposing to establish BCT requirements equivalent to BPT. As discussed in IX.C above, the requirements of the proposed BPT have been demonstrated to be technologically available and EPA's analyses show that the requirements are economically achievable.

Establishing BCT effluent limitations for a point source category begins by identifying technology options that provide additional conventional pollutant control beyond that provided by application of BPT effluent limitations. Conventional pollutants under the CWA are biochemical oxygen demand (BOD

5

), total suspended solids (TSS), fecal coliform, pH, and oil and grease. CWA section 304(a); 40 CFR 401.16. Stormwater discharges, if not adequately controlled, can contain very high levels of TSS. In addition, many of the construction materials used at the site can contribute BOD or oil and grease. Fecal coliform can also be present at elevated levels, due to natural sources (contributed by animal wastes) or if stormwater is not segregated from sanitary waste facilities. See Section VII for additional discussion of pollutant sources.

EPA evaluates the candidate BCT options by applying the two-part BCT cost test. The first part of the BCT cost test is the POTW test. To “pass” the POTW test, the cost per pound of conventional pollutant discharges removed in upgrading from BPT to the candidate BCT must be less than the cost per pound of conventional pollutant removed in upgrading POTWs from secondary treatment to advanced secondary treatment. Using the RS Means Historical Cost Indices, the inflation-adjusted POTW benchmark (originally calculated to be $0.25 in 1976 dollars) is $0.92 (2008 $). To examine whether an option passes this first test, EPA calculates incremental values of the candidate option relative to the proposed BPT (Option 1). EPA calculated the incremental cost per pound of conventional pollutants removed ($/lb TSS) for Option 2 to be $0.068. Since this result is less than the POTW benchmark, Option 2 passes the first part of the two-part BCT cost test. EPA also calculated the incremental cost per pound of conventional pollutants removed for Option 3, which is $0.074. Therefore, Option 3 also passes the first part of the BCT cost test.

To pass the second part of the BCT cost test, the industry cost effectiveness test, EPA computes a ratio of two incremental costs. The numerator is the cost per pound of conventional pollutants removed by the BCT candidate technology relative to BPT. The denominator is the cost per pound of conventional pollutants removed by BPT relative to no treatment (i.e., raw wasteload). As in the POTW test, the ratio of the numerator divided by the denominator is compared to an industry cost benchmark. The industry cost benchmark is the ratio of two incremental costs: The cost per pound to upgrade a POTW from secondary treatment to advanced secondary treatment, divided by the cost per pound to initially achieve secondary treatment from raw wasteload. If the calculated ratio is lower than the industry cost benchmark of 1.29 (i.e., the normalized cost increase must be less than 29 percent), then the candidate technology passes the industry cost test. The calculated ratio for Option 2 is 4.46; therefore, it fails the second part of the BCT cost test. The calculated ratio for Option 3 is 4.81; therefore, it also fails the second part of the BCT cost test. Therefore, EPA is proposing to set BCT equal to Option 1.

EPA estimated loading reductions, which ar

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