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Best Management Practices (BMP)

According to 40 CFR § 122.2, schedules of activities, prohibitions of practices, maintenance procedures, and other management practices to prevent or reduce the pollution of waters of the United States. BMPs also include treatment requirements, operating procedures, and practices to control plant site runoff, spillage or leaks, sludge or waste disposal, or drainage from raw material storage.


Clean Water Act (CWA)

The Clean Water Act is an act passed by the U.S. Congress to control water pollution. It was formerly referred to as the Federal Water Pollution Control Act of 1972 or Federal Water Pollution Control Act Amendments of 1972 (Public Law 92-500), 33 U.S.C. 1251 et seq., as amended by Public Law 96-483, Public Law 97-117, and Public Laws 95-217, 97-117, 97-440, and 100-04.

Code of Federal Regulations (CFR)

The document that codifies all rules of the executive departments and agencies of the federal government. It is divided into fifty volumes, known as titles. Title 40 of the CFR (referenced as 40 CFR) lists all environmental regulations.

Connection Permit

A permit issued by DOT-HWYS for a physical connection into the MS4.

Consent Decree

Consent Decree Civil Action No. CV05-00636-HG- KSC.

Construction Activity

The act or process of developing or improving land which involves the disturbance of land, and includes clearing, grading, and excavation.

Contract Construction Project

A construction activity, which is designed either by DOT HWYS’ personnel or by DOT-HWYS’ engineering consultant firms, and is constructed by a private contractor.

Critical Deficiency

Those deficiencies that pose an immediate threat for the discharge of pollutants to the storm drain system, surface water, or State Waters. Critical deficiencies include, but are not limited to, the following examples

  • Any observed discharge, or evidence of discharge, of untreated storm water or non-storm water to the storm drain system, surface waters, or State Waters generated by construction activity.
  • Absence of linear barriers and/or perimeter controls required by the BMP Plan.
  • There are identified storm drain inlets, surface waters, or State Waters within or adjacent to the project site in close proximity to disturbed soil areas without control measures in place that pose an immediate threat of untreated storm water discharges.
  • Work in an active stream channel or other surface water body without proper implementation of required BMPs.
  • Presence of any spilled oil or hazardous materials near to unprotected storm drain inlet, surface waters, or State Waters.

CWA Section 303(d) List

Under Section 303(d) of the Clean Water Act, states are required to compile a list of impaired waters that fail to meet any of their applicable water quality standards or cannot support their designated or existing uses. This list, called a “303(d) list” is submitted to Congress every two years, and states are required to develop a total maximum daily load (TMDL) for each pollutant causing impairment for water bodies on the list.



Any liquid, semi-solid, or solid substance that is released into and from the MS4.

Discharge Permit

A permit issued by DOT-HWYS to discharge storm water runoff into the MS4.

Disturbance of Land

The penetration, turning, or moving of soil or resurfacing of pavement with exposure of the base course or the exposure of bare soil or ground surface; including the land surface exposed by construction roads, baseyards, staging areas, demolition, headquarters, and parking areas. It includes “grubbing” in its normal meaning of the use of equipment to knock down and push vegetation out of the way, typically uprooting vegetation and disturbing the ground surface.


Encroachment Permit

A permit (e.g., Permit to Perform Work Upon State Highways, Permit to Discharge into the State Highways Drainage System, Permit to Connect to the State Highways Drainage System, etc.) issued by DOT-HWYS for activities undertaken by a non-DOT-HWYS entity (i.e., third party) that will occur within or affect DOT-HWYS’ right-of-way.

Encroachment Permit Construction Projects

Construction activity that occurs within DOT HWYS’ right-of-way and is not under the authority (funding) of or administered by DOT HWYS. Encroachment permit construction projects are required to obtain a Permit to Perform Work Upon State Highways prior to construction activities commencing.

Erosion Control

Stabilizing a disturbed or exposed surface area in order to prevent soil particles from being detached and causing sediment accumulation in nearby surface waters.




Good Housekeeping

A common practice related to the storage, use, or cleanup of materials performed in a manner that minimizes the discharge of pollutants.


Household Hazardous Waste

Leftover household products that contain corrosive, toxic, ignitable, or reactive ingredients.


Illegal Connection

Any connection to the MS4 that is not permitted by a connection permit from DOT-HWYS.

Illicit Discharge

Any discharge that is not composed entirely of storm water, with the exception of the following types of discharges (provided that they do not contain pollutants in amounts that will cause or contribute to a violation of an applicable water quality standard):

  • Water line flushing;
  • Diverted stream flows;
  • Rising ground waters;
  • Uncontaminated ground water infiltration (defined in 40 CFR §35.2005[20]);
  • Uncontaminated pumped ground water;
  • Discharges from potable water sources and foundation drains;
  • Air conditioning condensate;
  • Sea water;
  • Springs;
  • Water from crawl space pumps (including discharge from buildings with basements, and crawl space pumps used by utility companies to dewater utility manholes and other maintenance and operations of substructure facilities) and footing drains;
  • Lawn watering runoff, landscape irrigation, planter box runoff, and irrigation water, excluding runoff from commercial agriculture;
  • Water from individual residential car washing;
  • Water from charity car washes;
  • Flows from riparian habitats and wetlands;
  • Dechlorinated swimming pool discharges;
  • Exterior building wash water (water only);
  • Residual street wash water (water only), including wash water from sidewalks, plazas, and driveways, but excluding parking lots; and
  • Discharges or flows from firefighting activites.

Independent Inspections

Site inspections conducted on contract and encroachment permit construction projects by an independent inspector.

Independent Inspector

A qualified construction inspector that is not involved in a construction projects’ day-to-day planning, design, or implementation.






Low Impact Development (LID)

A comprehensive land planning and engineering design approach with a goal of maintaining and enhancing the pre-development hydrologic regime of urban and developing watersheds.


Major Deficiencies

Those deficiencies that are significant problems which could result in the discharge of pollutants to the storm drain system, surface waters, or State Waters. Major deficiencies include, but are not limited to, the following examples:

  • No BMP Plan or NPDES permit (if required).
  • Linear barriers and/or perimeter controls in areas tributary to a water body or drain inlet are installed as required by the BMP Plan, but are not functional. This includes silt fences that are not anchored properly, have collapsed, been driven over or overwhelmed by accumulated sediment.
  • Hazardous materials or waste is stored within the project without containment or implementation of BMPs.
  • Oil, fuel, or brake or transmission fluid spills covering more than one square yard and/or adjacent to protected storm drain inlets, surface waters, or State Waters.
  • Any discharge of sediment or other deleterious material resulting from dewatering operations conducted without implementation of required BMPs for dewatering.
  • Sediment tracking more than 50 feet from project ingress/egress location(s).
  • Expansion of the active disturbed soil area limit without written approval;
  • Soil stabilization and sediment controls are not installed in accordance with applicable construction site BMP Plan.
  • Sediment controls are installed in accordance with the BMP Plan, but there is a large unstabilized disturbed soil area with insufficient controls down gradient to prevent the discharge of untreated storm water to the storm drain system, surface waters, or State Waters if a rain event generates runoff.
  • Dust from project site visibly blowing off the site and into storm drain conveyances or adjacent surface water bodies.

Minor Deficiencies

Those deficiencies that do not pose a threat for discharge of untreated storm water or pollutants to the storm drain system, surface waters, or State Waters, but are not in strict conformance with the SWPPP or BMP Plan. Minor deficiencies include, but are not limited to, the following examples:

  • BMP Plan does not reflect current operations and an amendment is recommended.
  • BMPs are not deficient, but are not consistent with the BMP Plan.
  • Linear barriers and/or perimeter controls are installed as required by the BMP Plan, but require minor maintenance. For example, a silt fence which is not anchored properly throughout the entire length of an inlet protection device with some accumulated silt.
  • Soil stabilization or sediment controls are installed as required by the BMP Plan, but not properly maintained.
  • Site inspections by project staff are not being conducted at the required frequencies.
  • Non-storm water or waste management BMPs improperly maintained.
  • Oil, fuel, or brake or transmission fluid spills covering less than one square yard and not adjacent to storm drain inlets, surface waters, or State Waters.
  • Evidence of active wind erosion on unstabilized slopes/stock piles.
  • Minor tracking less than 50 feet from project ingress/egress locations.
  • Major deficiencies which are corrected prior to the inspector leaving the site.

MS4 Permit

National Pollutant Discharge Elimination System Permit No. HI S000001

Municipal Separate Storm Sewer System (MS4)

A conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, manmade channels, or storm drains) owned by a state, city, town, or other public body, that is designed or used for collecting or conveying storm water, that is not a combined sewer, and that is not part of a publicly owned treatment works [40 CFR122.26(b)(8)].


National Pollutant Discharge Elimination System (NPDES)

The national program for issuing, modifying, revoking and reissuing, terminating, monitoring and enforcing permits, and imposing and enforcing pretreatment requirements, under Sections 307, 318, 402, and 405 of the CWA.

Notice of Intent (NOI)

Form completed and signed by a construction site operator or an industrial facility operator notifying the DOH that the operator will comply with an applicable NPDES general permit.


Any substance assimilated by living things that promotes growth. The term is generally applied to nitrogen and phosphorus in wastewater, but is also applied to other essential and trace elements.



Outfall is a point source where the MS4 discharges to State Waters and does not include open conveyances connecting two MS4s, pipes, tunnels, or other conveyances which connect segments of the same stream or State Waters and are used to convey State Waters [40 CFR 122.26(b)(9)].


Permanent Best Management Practice (PBMP)

A specific practice intended to reduce storm water volume and/or the pollution typically associated with storm water runoff. Such practices may include LID design features, source control methods, or manufactured devices designed to capture pollutants.


Refer to the waste material that contaminates air, soil, or water. In the context of storm water quality, pollutants often refer to the following:

  • Nutrients – phosphorous and nitrogen;.
  • Suspended solids – sediment suspended in the water;
  • Organic carbon and hydrocarbons;
  • Bacteria;
  • Trace metals;
  • Pesticides; and
  • Trash and debris.

Program Element

Individual programs that comprise DOT-HWYS’ overall Storm Water Management Program (i.e., Public Education and Outreach Program, Construction Runoff Control Program, etc.)




Redevelopment Project

A project that consists of reconstruction of or new construction on an existing impervious area exceeding 5,000 square feet.

Routine Maintenance Projects

Scheduled or cyclical projects performed to preserve the life of a system; to restore the original function or delay the deterioration of an existing asset without substantially increasing its structural capacity; or to maintain the original line and grade, hydraulic capacity or original purpose of a facility, system or asset, in which maintenance activities does not go beyond the original footprint of the previous structure.



Organic or inorganic material that is carried by or is suspended in water and that settles out to form deposits in the storm drain system or receiving waters.

Service Contractor

The contractor or contractors procured by DOT-HWYS in order to provide various services.

Sheet Flow

Flow that occurs overland in places without defined channels. The flood water spreads out over a large area at a uniform depth. Also referred to as overland flow.


Any location in the State of Hawaii that DOT-HWYS owns, leases, or operates, and at which there is or will be construction resulting in ground-disturbing activities greater than or equal to one acre or that is otherwise subject to the NPDES storm water construction regulations set forth at 40 CFR § 122.26(b)(14)(x) or 40 CFR § 122.26(b)(15).

Source Control BMP

Appropriate operational or structural measures that prevent or reduce pollutants from entering storm water. Examples of operational source control BMPs include good housekeeping practices, spill prevention, and employee training. Structural source control BMPs consist of enclosures or roofs for working areas where pollutants are present or installing devices that direct contaminated storm water to appropriate treatment BMPs.

State Waters

As defined by section 342D-1, HRS, means all waters, fresh, brackish, or salt around and within the State, including, but not limited to, coastal waters, streams, rivers, drainage ditches, ponds, reservoirs, canals, ground waters, and lakes; provided that drainage ditches, ponds, and reservoirs required as part of a water pollution control system are excluded. In accordance with HAR 11-54-1, this definition applies to all State Waters, including wetlands, subject to the following exceptions: (1) This chapter [HAR 11-54-1] does not apply to groundwater, except the director may in the director’s discretion take appropriate actions when the director believes that the discharge of pollutants to the ground or groundwater has adversely affected, is adversely affecting, or will adversely affect the quality of any State Water other than groundwater. (2) This chapter does not apply to drainage ditches, flumes, ponds and reservoirs that are required as part of a water pollution control system. (3) This chapter does not apply to drainage ditches, flumes, ponds, and reservoirs that are used solely for irrigation and do not overflow into or otherwise adversely affect the quality of any other State Waters, unless such ditches, flumes, ponds, and reservoirs are waters of the United States as defined in 40 C.F.R. section 122.2. The State of Hawaii has those boundaries stated in the Hawaii Constitution, art. XV § l.

Storm Water

Water that accumulates on land as a result of storms and can include runoff from urban areas such as roads and highways.

Storm Water Runoff

Precipitation which flows over the ground.


An elongated depression in the land surface that is at least seasonally wet, usually heavily vegetated, and normally without flowing water. Swales discharge storm water into primary drainage channels and may provide some groundwater recharge.


Top of Bank (TOB)

The break in slope between the bank and surrounding terrain. TOB is the point closest to the boundary of the active floodplain of a stream where a break in the slope of the land occurs.

Total Maximum Daily Load (TMDL)

A TMDL establishes the maximum amount of an impairing substance or stressor that a water body can assimilate and still meet Water Quality Standards and allocates that load among pollution contributors. TMDLs are also a tool for implementing State Water quality standards. They are based on the relationship between pollution sources and in-stream water quality conditions. A TMDL addresses a single pollutant or stressor for each water body.






Waste Load Allocation (WLA)

The maximum quantity of pollutants each discharger of waste is allowed to release into a particular waterway as set by an authority. Discharge limits are usually required individually for each specific water quality criterion.

Water Quality Standards

State adopted and USEPA-approved ambient standards for water bodies. The standards prescribe the use of water body and establish the water quality criteria that must be met to protect water bodies.


The area of land that catches rain and snow and drains or seeps into a receiving water such as marsh, stream, river, lake, or ocean.