EPA related terminology

Steven Button

Some definitions and clarification on terminology related to current topics of conversation - may help some of us who are not 'up to speed' on issues. Please read to become more educated on the Clean Water Act (CWA) and rinse water related issues that we face as pressure washing contractors. Information taken from EPA Storm Water Phase II Compliance Assistance Guide.

Regulatory definition of MS4

According to 40 CFR 122.26(b)(8), “municipal separate storm sewer means a conveyance or
system of conveyances (including roads with drainage systems, municipal streets, catch basins,
curbs, gutters, ditches, man-made channels, or storm drains):
(i) Owned or operated by a State, city, town, borough, county, parish, district, association,
or other public body (created by or pursuant to State law)...including special districts
under State law such as a sewer district, flood control district or drainage district, or
similar entity, or an Indian tribe or an authorized Indian tribal organization, or a
designated and approved management agency under section 208 of the Clean Water
Act that discharges into waters of the United States.
(ii) Designed or used for collecting or conveying storm water;
(iii) Which is not a combined sewer; and
(iv) Which is not part of a Publicly Owned Treatment Works
(POTW) as defined at 40 CFR 122.2."

Waters of the United States

Waters of the United States include interstate lakes, rivers, streams
(including intermittent streams), mudflats, sandflats, wetlands,
sloughs, prairie potholes, wet meadows, playa lakes, or natural ponds
the use, degradation, or destruction of which would affect or could
affect interstate or foreign commerce. (Waste treatment systems,
including treatment ponds or lagoons designed to meet the
requirements of CWA are not waters of the United States.) A
complete definition can be found at 40 CFR 122.2.


Storm Water Pollution Prevention Plan

Pollutants of concern

Pollutants of concern include sediment or a parameter that
addresses sediment (such as total suspended solids, turbidity, or
siltation) and any other pollutant that has been identified as a cause
of impairment of a receiving waterbody.

Structural BMPs

• Storage Practices. Storage or detention BMPs control storm water by gathering
runoff in wet ponds, dry basins, or multichamber catch basins and slowly releasing it to receiving waters or drainage systems. These practices both control storm water volume and settle out particulates for pollutant removal.

• Infiltration Practices. Infiltration BMPs are designed to facilitate the percolation
of runoff through the soil to ground water, and, thereby, result in reduced storm
water quantity and reduced mobilization of pollutants. Examples include
infiltration basins/trenches, dry wells, and porous pavement.

• Vegetative Practices. Vegetative BMPs are landscaping features that, with
optimal design and good soil conditions, enhance pollutant removal,
maintain/improve natural site hydrology, promote healthier habitats, and increase
aesthetic appeal. Examples include grassy swales, filter strips, artificial
wetlands, and rain gardens.

What Is An “Illicit Discharge”?

Federal regulations define an illicit discharge as “...any discharge to an MS4 that is
not composed entirely of storm water...” with some exceptions. These exceptions
include discharges from NPDES-permitted industrial sources and discharges from fire-
fighting activities. Illicit discharges (see Table 4-2) are considered “illicit” because MS4s
are not designed to accept, process, or discharge such non-storm water wastes. It is
important to note that "illicit" does not mean "illegal." Not every illicit discharge is
necessarily a prohibited illegal discharge.