Forensic Evaluation of Non-Dispersables: New York City Law Department 

To read entire study, click here

The New York City Department of Environmental Protection’s (NYC DEP’s) Wards Island Wastewater Treatment Facility is located on Wards Island in the East River (between Manhattan and the Astoria section of Queens). Fuss & O’Neill met in the Administration Building of the facility with NYC DEP Division Chief of Operations, Jerry Fragias, and NYC DEP Wards Island Process Engineer Yu-Tung Chan on the afternoon of Tuesday, February 16.

The facility has a design capacity to provide full treatment of 275 million gallons of wastewater per day (MGD) and is presently required to maintain the ability to pump 320 MGD, per Mr. Chan. Although the facility is required to maintain a pump capacity of 320 MGD, some storm events cause the plant to reach over 400+ MGD. We understand that this facility is continuously struggling to manage the increasing volumes of non-dispersible materials present in influent. These materials cause operational challenges at points in the treatment process from headworks (screening and material disposal) through secondary treatment (interfering with valves and blocking channels) and sludge management (pump clogging). The purpose of this forensic evaluation was to identify the materials present in a “snapshot” of influent to this facility from a combined system (i.e., both sanitary sewer and storm drain flows). The “snapshot” would compare items entering the facility through two separate channels: one conveying flow from Manhattan, and one conveying flow from the Bronx.

The Manhattan channel and the Bronx channel are each served by three functional mechanical screens (a fourth screen at each of the two locations is presently being replaced). The screens use automatic raking mechanisms to scrape debris from evenly spaced bars and deposit the debris into dumpsters, which are emptied manually. The Fuss & O’Neill team had the opportunity to visit the screening system associated with the Bronx channel the afternoon of Tuesday, February 16, but did not see the Manhattan facility. This process is nearly continuous: one dumpster is nearly full in the short time it’s taken the operator to empty the other two dumpsters.

To read entire study, click here.