Case Study

Allegheny Township, Outfall Screening

NPDES MS4 PROGRAM

(Minimum Control Measure: Illicit Discharge Detection & Elimination)

Allegheny Township, Westmoreland County, Pennsylvania

Background:

As a continuation of Year 5 of the Department of Environmental Protection’s National Pollution Discharge and Elimination System (NPDES) Municipal Separate Storm Sewer System (MS4) Program, AlleghenyTownship contracted Senate Engineering Company to assist them in part three of the six Best Management Practices category: Illicit Discharge Detection and Elimination.  This federal regulation consists of:

Field screening of outfalls to identify sources of illicit discharges. Priority Areas as defined under DEP’s “Urbanized Areas” must be field screened.  Field screening consists of both physical characterization of the outfall, as well as, chemical laboratory bacterial testing.  Screening should be conducted at least 72 hours since the last precipitation even and at least 48 hours should pass between the first screening at a particular outfall and the second screening of the outfall. 

Physical characterization is designed to look for color, odor, turbidity, sheen/scum

In-field analysis determines the pH, and if any cholrine, copper, phenol, detergents are present, flow is also determined

Water sample and lab analysis characterizes if any bacteria such as, fecal colliforms and e.coli are present.

Once the results of lab analysis and physical screening are returned, municipalities must identify potential sources of contamination; the source of the flow must be traced upstream using maps, inspecting manholes and storm drains.  Determine if the flow is from illegal dumping or an improper connection. Municipalities must determine the most appropriate action in removing or correcting the discharge.