United States Office of Water EPA 833-F-99-013

Environmental Protection (4203) April 1999

Agency Fact Sheet 3.0

Storm Water Phase II

Proposed Rule

Construction Program

Overview

This fact sheet is based on the Storm Water Phase II Proposed Rule. Therefore, the information provided herein is subject to

change upon publication of the final Phase II rule in November 1999. A revised series of fact sheets will be provided at that

time. A comprehensive list of the current fact sheets is in the text box at left.

The 1972 amendments to the Federal Water Pollution Control Act, later referred to as the Clean

Water Act (CWA), prohibit the discharge of any pollutant to navigable waters of the United States

from a point source unless the discharge is authorized by a National Pollutant Discharge Elimination

System (NPDES) permit. Efforts to improve water quality under the NPDES program traditionally

have focused on reducing pollutants in industrial process wastewater and municipal sewage treatment

plant discharges. Over time, it has become evident that more diffuse sources of water pollution, such

as storm water runoff from construction sites, are also significant contributors to water quality

problems.

Sediment runoff rates from construction sites are typically 10 to 20 times greater than those from

agricultural lands, and 1,000 to 2,000 times greater than those of forest lands. During a short period

of time, construction activity can contribute more sediment to streams than can be deposited over

several decades, causing physical and biological harm to our Nation’s waters.

In 1990, EPA promulgated rules establishing Phase I of the NPDES storm water program. Phase I

addresses, among other discharges, discharges from large construction activities disturbing 5 acres or

more of land. Phase II of the NPDES storm water program proposes to cover additional, smaller,

construction activities. Phase II is scheduled to become final in November 1999 with permits issued

within 3 years and 90 days of publication of the final rule. This fact sheet outlines the construction

activities covered by Phase I and proposed to be covered by Phase II, including possible waiver

options from Phase II coverage, as well as the proposed Phase II construction program requirements.

Who Is Currently Covered Under the Phase I Rule?

Sites Five Acres and Larger

The Phase I NPDES storm water permitting rule identifies eleven categories of industrial activity in

the definition of “storm water discharges associated with industrial activity” that must obtain an

NPDES permit. One of these categories is construction activity. The Phase I rule requires all

operators of construction activity disturbing 5 or more acres of land to apply for a storm water

permit. Operators of sites disturbing less than 5 acres also are required to obtain a permit under

Phase I if they are part of a “larger common plan of development or sale” with a planned disturbance

of 5 or more acres. “Disturbance” refers to exposed soil resulting from activities such as clearing,

grading, and excavating. Construction activities can include road building, construction of residential

houses, office buildings, industrial sites, or demolition.

What Is Meant by a “Larger Common Plan of Development or Sale”?

As defined in EPA’s NPDES storm water general permit for Phase I construction, a “larger

common plan of development or sale” means a contiguous area where multiple separate and

distinct construction activities are occurring under one plan (e.g., the operator is building on three

half-acre lots in a 6-acre development). The “plan” in a common plan of development or sale is 

Storm Water Phase II

Proposed Rule

Fact Sheet Series

Overview

1.0 – Storm Water Phase II

Proposed Rule Overview

Small MS4 Program

2.0 – Small MS4 Storm Water

Program Overview

2.1 – Who’s Covered? Designation

and Waivers of Regulated Small

MS4s

2.2 – Urbanized Areas: Definition

and Description

Minimum Control Measures

2.3 – Public Education and

Outreach Minimum Control

Measure

2.4 – Public Participation/

Involvement Minimum Control

Measure

2.5 – Illicit Discharge Detection and

Elimination Minimum Control

Measure

2.6 – Construction Site Runoff

Control Minimum Control Measure

2.7 – Post-Construction Runoff

Control Minimum Control Measure

2.8 – Pollution Prevention/Good

Housekeeping Minimum Control

Measure

2.9 – Permitting and Reporting:

The Process and Requirements

2.10 – Federal and State-Owned

MS4s: Program Implementation

Construction Program

3.0 – Construction Program

Overview

Industrial “No Exposure”

4.0 – Conditional No Exposure

Exemption for Industrial Activity
Fact Sheet 3.0 – Construction Program Overview Page 2

broadly defined as any announcement or piece of documentation

(including a sign, public notice or hearing, sales pitch,

advertisement, drawing, permit application, zoning request,

computer design, etc.) or physical demarcation (including

boundary signs, lot stakes, surveyor markings, etc.) indicating that

construction activities may occur on a specific plot.

What Is the Definition of an “Operator” of a

Construction Site?

As defined in EPA’s storm water general permit for Phase I

construction, an “operator” is the party or parties that has:

 Operational control of construction project plans 

and specifications, including the ability to make

modifications to those plans and specifications, and

 Day-to-day operational control of those activities that

are necessary to ensure compliance with a storm water

pollution prevention plan (SWPPP) for the site or other

permit conditions (e.g., they are authorized to direct

workers at a site to carry out activities required by the

SWPPP or comply with other permit conditions). 

There may be more than one party at a site performing the tasks

related to “operational control” as defined above. Depending on

the site and the relationship between the parties (e.g., owner,

developer, contractor), there can either be a single party acting as

site operator and consequently be responsible for obtaining permit

coverage, or there can be two or more operators, all obligated to

seek permit coverage. It is important to note that NPDESauthorized States may use a different definition of “operator” than

the one above.

How Is the Proposed Phase II Construction Rule

Related to the Phase I Construction Rule?

I

n 1992, the Ninth Circuit court remanded for further

proceedings portions of EPA’s existing Phase I storm water

regulation related to the category of discharges from construction

activity (NRDC v. EPA, 966 F.2d at 1292). The court concluded

that the 5-acre threshold used for defining construction activity as

“industrial activity” (and therefore needing a permit) was

improper because EPA had failed to identify information “to

support its perception that construction activities on less than 5

acres are non-industrial in nature” (and therefore do not need a

permit) (966 F.2d at 1306). Based on consultations with the

Storm Water Phase II Federal Advisory Subcommittee, EPA

responded to the court’s decision by designating under Phase II

storm water discharges from construction sites less than 5 acres as

sources that should be regulated to protect water quality. The

Phase II Proposed Rule designates these sources as “storm water

discharges associated with other activity” (rather than storm water

associated with industrial activity).

Who Would Be Covered Under the Proposed

Phase II Construction Rule?

Sites Between One and Five Acres

The Storm Water Phase II Proposed Rule would automatically

cover, under the NPDES storm water permitting program, all

owners or operators of construction site activities that result in a

land disturbance of equal to or greater than 1 but less than 5

acres.

Sites Less Than One Acre

Site activities disturbing less than 1 acre would also be included

in the NPDES storm water program if they are part of a larger

common plan of development or sale with a planned disturbance

of equal to or greater than 1 acre but less than 5 acres, or if they

are designated by the NPDES permitting authority. As proposed,

the NPDES permitting authority may designate construction

activities disturbing less than 1 acre if a project is deemed to have

the potential for adverse impacts on water quality or for

significant contribution of pollutants based on a Total Maximum

Daily Load (TMDL), watershed, or other local assessment.

Would Waivers Be Available for Owners or

Operators of Regulated Construction Activity?

Yes, but only for Phase II construction activity. Under the

Phase II Proposed Rule, NPDES permitting authorities

would have the option of providing a waiver from the

requirements to owners or operators of Phase II construction

activity who could certify to any one of three conditions: 

 Low predicted rainfall potential (i.e., activity occurs

during a negligible rainfall period), where the rainfall

erosivity factor (“R” in the Revised Universal Soil Loss

Equation [RUSLE]) would be less than 2 during the

period of construction activity.

Low predicted soil loss – on a case-by-case basis –

where the annual soil loss for a site would be less than 2

tons/acre/year as determined using RUSLE, assuming the

constants of no ground cover and no runoff controls in

place.

 A determination that storm water controls are not

necessary based on either:

(A) Wasteload allocations that are part of TMDLs that

address the pollutants of concern for construction

activities; OR

 

(B) A comprehensive watershed plan, implemented

for the receiving waterbody, that includes the

equivalents of TMDLs and addresses the

pollutants of concern for construction activities.
Fact Sheet 3.0 – Construction Program Overview Page 3

The intent of the waiver provision is to waive only those sites that

are highly unlikely to have a negative effect on water quality. 

Therefore, before applying for a waiver, owners or operators of

Phase II construction activity would be encouraged to consider

the potential water quality impacts that may result from their

project and to carefully examine such factors as proximity to

water resources and sensitivity of receiving waters.

a. What is RUSLE in Waivers  and ?

Proposed waivers  and would use the RUSLE as the

means of determining if the potential for polluted discharge is

low enough to justify a waiver from the requirements. The

Universal Soil Loss Equation (USLE) is a well established

method for predicting soil loss from construction sites. 

Developed initially by the U.S. Department of Agriculture as a

predictive tool to measure soil loss from agricultural lands at

various times of the year on a regional basis, the USLE was

identified in the early 1970s as a technique that could be useful in

predicting construction site soil losses.

The USLE predicts construction site soil loss using six variables:

rainfall erosivity; soil erodibility; length of slope; steepness of

slope; cover; and practice. A refinement of the USLE is reflected

in the RUSLE, which provides a broader range of data within the

individual variables. Once the site-specific variables that make up

the RUSLE are determined, the values for rainfall erosivity or soil

loss can be calculated.

An electronic version of RUSLE can be downloaded at

http://danpatch.ecn.purdue.edu/~engelb/agen526/rusle.html. 

In addition, the RUSLE user’s guide can be downloaded at 

http://www.itc.nrcs.usda.gov/focs/RUSLE/userguid/ruslug1.html.

b. What is a “TMDL” in Waiver ?

For impaired waters where technology-based controls required

by NPDES permits are not achieving State water quality

standards, the CWA requires the TMDL process be implemented

for those waters. The TMDL process establishes the maximum

amount of pollutants a waterbody can assimilate before water

quality is impaired, then requires that this maximum level not be

exceeded.

A TMDL is done for each pollutant that is found to be

contributing to the impairment of a waterbody or a segment of a

waterbody. To allow a waiver for construction activities, a

TMDL would need to address Total Suspended Solids, the

major pollutant of concern. Additional TMDLs addressing

common pollutants from construction sites such as nitrogen,

phosphorus, and oil and grease also may be necessary to ensure

water quality protection and allow a waiver from the NPDES

storm water program.

A TMDL assessment determines the source or sources of a

pollutant of concern, considers the maximum allowable level of

that pollutant for the waterbody, then allocates to each source or

category of sources a set level of the pollutant that it is allowed to

discharge into the waterbody. Allocations to point sources are

called wasteload allocations.

c. How Would an Owner or Operator Qualify for,

and Certify to, Waiver ?

EPA expects that when TMDLs, or the equivalents of TMDLs,

are completed, there may be a determination that certain

classes of sources, such as small construction sites, would not

have to control their contribution of pollutants of concern to the

waterbody in order for the waterbody to be in attainment with

water quality standards (i.e., these sources were not assigned

wasteload allocations). In such a case, to qualify for waiver 

the owner or operator of the construction site would need to

certify on a form that its construction activity will take place, and

the storm water discharges will occur, within the area covered

either by the TMDLs or a comprehensive watershed plan that

includes the equivalents of TMDLs. The certification form would

likely be provided by the NPDES permitting authority.

What Would Be Required Under the Phase II

Construction Program?

The Phase II Proposed Rule would require owners or operators

of Phase II construction sites, nationally, to obtain an NPDES

permit and implement practices to minimize pollutant runoff. It

is important to note that, locally, these same sites may also be

covered by State, Tribal, or local construction runoff control

programs (see Fact Sheets 2.6 and 2.7 for information on the

proposed Phase II small MS4’s construction program). For the

Phase II construction program, EPA has taken an approach

similar to the Phase I approach where the program requirements

are not fully defined in the rule but rather in the NPDES permit

by the NPDES permitting authority

EPA would likely recommend that the NPDES permitting

authorities use their existing Phase I NPDES construction general

permits as a guide to developing their Phase II construction

permits. In doing so, the Phase II requirements would be similar

to the three general Phase I requirements summarized below.

 Submission of a Notice of Intent (NOI) that includes

general information and a certification that the activity

will not impact endangered or threatened species. This

certification is unique to EPA’s NOI and is not a

requirement of most NPDES-delegated State’s NOIs;
Fact Sheet 3.0 – Construction Program Overview Page 4

 The development and implementation of a Storm Water

Pollution Prevention Plan (SWPPP) with appropriate

BMPs to minimize the discharge of pollutants from the

site; and

 Submission of a Notice of Termination (NOT) when

final stabilization of the site has been achieved as

defined in the permit or when another operator has

assumed control of the site.

What are Some Recommended BMPs for Phase II 

Construction Sites?

The approach and BMPs for controlling pollutants in storm

water discharges from smaller Phase II sites may vary from

those used for larger Phase I sites since their characteristics can

differ in many ways. For example, operators of smaller sites may

have more limited access to qualified design personnel and

technical information. Also, activity on smaller sites may allow

for less space for installing and maintaining certain BMPs.

As is the case with all construction sites, erosion and sediment

control at small construction sites is best accomplished with

proper planning, installation, and maintenance of controls. The

following practices have shown to be efficient, cost effective, and

versatile for small construction site operators to implement. The

practices are divided into two categories: non-structural and

structural.

 Non-Structural BMPs

• Minimizing Disturbance

• Preserving Natural Vegetation

• Good Housekeeping

 Structural BMPs

Erosion Controls

• Mulch

• Grass

• Stockpile Covers

Sediment Controls

• Silt Fence

• Inlet Protection

• Check Dams

• Stabilized Construction Entrances

• Sediment Traps

Most erosion and sediment controls require regular maintenance

to operate correctly. Accumulated sediments should be removed

frequently and materials should be checked periodically for wear. 

Regular inspections by qualified personnel, which can allow

problem areas to be addressed, should be performed after major

rain events.

For Additional Information

Contacts

 U.S. EPA Office of Wastewater Management

• Phone : 202 260-5816

• E-mail: SW2@epa.gov

• Internet: www.epa.gov/owm/sw2.htm

 Your local soil conservation district office. They can

provide assistance with RUSLE and other conservation

related issues. 

• A list of conservation district contacts is available

at: www.nacd.net.org/about/statelist.htm

Reference Documents

 Storm Water Phase II Proposed Rule Fact Sheet Series.

• Contact the U.S. EPA Water Resource Center at

202 260-7786 or at waterpubs@epa.gov 

• Internet: www.epa.gov/owm/sw2.htm

 Storm Water Phase II Proposed Rule, published on 

Jan. 9, 1998 in the Federal Register (63 FR 1536).

• Internet: www.epa.gov/owm/sw2.htm

 Predicting Soil Erosion by Water: A Guide to

Conservation Planning With the Revised Universal Soil

Loss Equation (RUSLE).

• Copies can be obtained from USDA-ARS,

Southwest Watershed Research Center, 2000 East

Allen Road, Tucson, AZ 85719.

 Guidance for Water Quality Based Decisions: The

TMDL Process. April 1991. U.S. EPA Office of

Water. EPA 440/4-91-001.

• Internet: www.epa.gov/OWOW/tmdl.

 NPDES General Permits for Storm Water Discharges

from Construction Activities, published on Feb. 17,

1998 in the Federal Register (63 FR 7857).