Lilly, L, Law, N, Torella, A, McCann, D, and Parkerd, P. 2014. Pollutant Analysis of HVAC Discharges in Montgomery County, Maryland: Center for Watershed Protection, Ellicott City, MD.

IDDE, pollutant, HVAC, discharge

In the Chesapeake Bay watershed, a Bay-wide total maximum daily load for nutrients and sediment is driving state and local efforts to account for every pound of pollutant that can be prevented from entering the Bay. Much of the effort focuses on the treatment of uncontrolled stormwater runoff; however, nonstormwater discharges have a significant and quantifiable pollutant load, much of which can be detected and eliminated through the effective implementation of an illicit discharge detection and elimination (IDDE) program. Montgomery County, Maryland, a Phase I municipal separate storm sewer system (MS4) operator, found an unexpected and ubiquitous source of pollution to the MS4 during routine IDDE investigations. The County initiated a special IDDE study on pollutant contributions from heating, ventilation, and air conditioning (HVAC) system discharges. Of the 73 buildings assessed, 27% had a potential HVAC discharge. The study found elevated concentrations of nitrogen and heavy metals, most of them exceeding water quality standards. The sources of contamination were biocide products, illicit cooling tower connections, water from condenser coil washdown, and refrigeration leaks. Given the ability to identify and quantify HVAC discharges, we provide management and research recommendations to eliminate this illicit discharge and improve methods to detect this source through IDDE programs.